JP2010261395A - Ignition control device for internal combustion engine - Google Patents

Abstract

In an ignition control device for an internal combustion engine, an air-fuel mixture can be ignited more appropriately.
An ignition control device (10) for an internal combustion engine includes a first coil (220a) capable of generating a first current as a secondary current and a second coil capable of generating a second current as a secondary current. (220b), a first spark plug (230a) that can be discharged by being supplied with a secondary current, a second spark plug (230b) that can be discharged by being supplied with a secondary current, and a first current Switch elements (220a, 220b) capable of supplying a second current to either one of the first spark plug and the second spark plug, and a second current, Control means (100) for controlling the switch element is provided so as to supply the first current and the second current to either one of the spark plugs at a predetermined timing according to the operating state of the internal combustion engine.
[Selection] Figure 2

Description

  The present invention relates to the technical field of an ignition control device for an internal combustion engine.

  As this type of device, Patent Literature 1 discloses an ignition device for an internal combustion engine in which the ignition plug of each cylinder is connected to a dedicated ignition coil, and each ignition coil is driven when the cylinder is ignited. In particular, there is disclosed an ignition device having a diode in which secondary sides of ignition coils whose phases are different from each other by 360 ° are connected to each other and a current is allowed to flow in each ignition coil connected in parallel.

  Patent Document 2 discloses a multi-discharge ignition device for an internal combustion engine. In particular, a technique relating to a so-called overlap discharge type ignition device is disclosed in which processing such as additionally superimposing an output current of a booster circuit provided separately on a high output current obtained on the secondary side of the ignition coil is performed. ing.

  Patent Document 3 discloses an ignition device that can apply an existing control unit of a one-point ignition engine to multipoint ignition. In particular, a technique relating to an ignition device that ignites a main ignition plug and a sub ignition plug having different cylinders with one ignition coil is disclosed.

  Further, in Patent Document 4, in an engine having three or more spark plugs arranged in series and having swirl generation means, the ignition energy of the sub spark plug is larger than that of the main spark plug or the discharge period of the sub spark plug is made longer. A technique related to an ignition device to be set is disclosed.

  In Patent Document 5, a plurality of sub-ignitions are arranged on a part of the piston or the wall surface of the combustion chamber, a main ignition is arranged near the center, the main and the sub are electrically connected in series, In particular, a technique related to an ignition device connected in parallel is disclosed.

  Patent Document 6 discloses a technique related to an ignition device in which DC / DC is separately mounted in a coil and the amount of current is variable.

Patent Document 7 discloses a technique for detecting misfire based on an ion current of a spark plug. Also, Patent Document 8 and Patent Document 9 disclose ignition by a leakage current between detected spark plug electrodes. There is disclosed a technique for detecting a so-called smoldering of a spark plug, a phenomenon in which a substance such as carbon adheres to the surface of the insulator of the plug and the resistance value (that is, insulation resistance) between the electrodes of the spark plug decreases. .

Japanese Unexamined Patent Publication No. 63-005165 Patent 3061540 JP 2005-163550 A JP-A-8-4641 JP 2001-12337 A JP 2006-63973 A JP 2006-336534 A Japanese Patent Laid-Open No. 11-50941 Japanese Patent Laid-Open No. 11-13620

  However, according to Patent Document 1 and the like described above, the required discharge state of the spark plug differs depending on the operating state of the internal combustion engine, and therefore there is a possibility that the air-fuel mixture cannot be properly ignited. Problems arise.

  Therefore, the present invention has been made in view of the above-described problems, and an object thereof is to provide an ignition control device for an internal combustion engine that can ignite an air-fuel mixture more appropriately.

  In order to solve the above problems, a first internal combustion engine ignition control device according to the present invention is an ignition control device for a spark plug provided in a cylinder of an internal combustion engine, and generates a first current as a secondary current. A first coil capable of generating a second current that is a secondary current, a first spark plug that can be discharged by being supplied with the secondary current, and the secondary current being supplied The second spark plug that can be discharged by the discharge and the generated first current can be supplied to any one of the first spark plug and the second spark plug, and the generated A switching element capable of supplying the second current to any one of the spark plugs, and supplying the first current and the second current at a predetermined timing according to an operating state of the internal combustion engine. Supply each spark plug Sea urchin, and a control means for controlling said switching element.

  In order to solve the above problems, a second internal combustion engine ignition control apparatus according to the present invention is an ignition control apparatus for an ignition plug provided in a cylinder of an internal combustion engine, and generates a first current as a secondary current. A first coil capable of generating a second current that is a secondary current, a first spark plug that can be discharged by being supplied with the secondary current, and the secondary current being supplied The second spark plug that can be discharged by the discharge and the generated first current can be supplied to any one of the first spark plug and the second spark plug, and the generated A switching element capable of supplying the second current to any one of the spark plugs, a specifying means for specifying a combustion state in the cylinder, and the specified the first current and the second current. At a predetermined timing according to the combustion state Wherein to each supplied to one of the spark plugs, and a control means for controlling said switching element.

  The operation and other advantages of the present invention will become apparent from the best mode for carrying out the invention described below.

It is the schematic diagram which showed typically the ignition control apparatus of the internal combustion engine which concerns on 1st Embodiment. It is the block diagram which showed the basic composition of the ignition device which concerns on this embodiment typically. It is the block diagram which showed typically the basic composition of the coil part in the ignition device which concerns on this embodiment. It is the table | surface which showed notionally the kind of operation | movement of the switch element which concerns on this embodiment. FIG. 5 is a diagram (FIG. 5A) schematically showing ignition timings in the four cylinders according to the present embodiment, and a table (FIG. 5B) conceptually showing types of operation of the switch elements. . It is the table | surface which showed the time change of the discharge current as a factor in the pattern of the discharge state of the spark plug which concerns on this embodiment, an effect, and the operation area | region applied. It is the block diagram which showed the basic composition of the ignition device which concerns on 2nd Embodiment typically. It is the table | surface which showed the combination of the spark plug which actually performs ignition in the ignition device which concerns on 2nd Embodiment, and the number of the coil parts used as the supply source which supplies an electric current to the said spark plug. It is the block diagram which showed the basic composition of the ignition device which concerns on 3rd Embodiment typically. It is the table | surface which showed the combination of the spark plug which actually performs ignition in the ignition device which concerns on 3rd Embodiment, and the number of the coil parts used as the supply source which supplies an electric current to the said spark plug. It is the graph which showed typically the operation field which switches the pattern of the discharge state concerning a 4th embodiment. Cross-sectional view of the cylinder (FIG. 12 (a)) schematically showing the state of the combustion chamber at the time of performing EGR or air lean burn according to the fourth embodiment, and the discharge state with time variation of current It is the shown graph (FIG.12 (b)). A cross-sectional view of the cylinder schematically showing the combustion chamber during stratified combustion according to the fourth embodiment (FIG. 13A), and a graph showing the discharge state as a function of time (FIG. 13B) )). It is the table | surface which showed the pattern of the driving | operation area | region and discharge state in case each cylinder which concerns on 4th Embodiment has one spark plug. It is the table | surface which showed the pattern of the driving | operation area | region and discharge state in case each cylinder which concerns on 4th Embodiment has a some ignition plug. It is the graph which showed the time change of three types of combustion pressure for determining the combustion state containing the misfire which concerns on 5th Embodiment. A graph (FIG. 17A) showing a time change of carbon monoxide (HC) concentration or a time change of oxygen (O2) concentration for determining a combustion state including misfire according to the fifth embodiment, and misfire It is the graph (FIG.17 (b)) which showed the time change of the carbon dioxide (CO2) density | concentration for determining the combustion state containing oxygen. It is the flowchart which showed the flow of the determination process in order to determine the combustion state containing misfire using the ion current which concerns on 5th Embodiment. It is the flowchart which showed the flow of the switching control process which switches the pattern of a discharge state according to the combustion state containing misfire in case each cylinder which concerns on 5th Embodiment has one spark plug. It is the flowchart which showed the flow of the switching control process which switches the pattern of a discharge state according to the combustion state containing misfire in case each cylinder which concerns on 5th Embodiment has a some ignition plug. It is the flowchart which showed the subroutine of the flow of the switching control process which switches the pattern of the discharge state shown by FIG. It is the flowchart which showed the flow of the switching control process which switches the pattern of a discharge state according to generation | occurrence | production of the smoldering concerning 6th Embodiment. It is the block diagram which showed the mode that the pattern of the discharge state was switched in the ignition device which concerns on 6th Embodiment. It is the flowchart which showed the flow of the switching control process which switches the pattern of a discharge state according to the progress degree of wear of the spark plug which concerns on 7th Embodiment. It is the graph which showed the correlation with the abrasion amount of the spark plug which concerns on 7th Embodiment, and the frequency | count of discharge. Schematic diagram (FIG. 26 (a)) schematically showing discharge with a spark plug with little wear according to a general example (FIG. 26 (a)), schematic diagram schematically showing discharge with a spark plug with advanced wear according to a comparative example ( FIG. 26 (b)) and a schematic diagram (FIG. 26 (b)) schematically showing discharge in the spark plug in which wear has progressed according to the seventh embodiment.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
(Basic configuration)
First, a basic configuration of an ignition control device for an internal combustion engine according to a first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a schematic diagram schematically showing the internal combustion engine ignition control apparatus according to the first embodiment.

  As shown in FIG. 1, the internal combustion engine ignition control apparatus 10 according to the first embodiment includes an ECU 100 and an engine 300.

  The ECU 100 is an electronic control unit that includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like, and controls the entire operation of the vehicle 10. It is an example of a “control device”. The ECU 100 is configured to execute a discharge state pattern switching control process, which will be described later, in accordance with a control program stored in the ROM.

  The ECU 100 is an integrated electronic control unit that functions as an example of the “ignition control device for an internal combustion engine” according to the present invention. Therefore, all the operations in the “control unit” according to the present invention are executed by the ECU 100. However, the physical, mechanical and electrical configurations of the respective means according to the present invention are not limited to this, and for example, these include various computer systems such as a plurality of ECUs, various processing units, various controllers or microcomputer devices. Etc. may be configured.

  The engine 300 is an in-line four-cylinder gasoline engine that is configured to function as a power source of the vehicle 10 and is an example of the “internal combustion engine” according to the present invention. The "internal combustion engine" in the present invention has, for example, a plurality of cylinders, and when a fuel that can take various forms such as gasoline, alcohol, or a mixed fuel thereof is burned in a combustion chamber in each of the plurality of cylinders. It is an engine that can output at least part of the generated power to a vehicle axle via an engine output shaft such as a crankshaft via a mechanical transmission path such as a piston and a connecting rod, and the fuel For example, it is a concept encompassing an engine having a so-called “direct injection” mode in which fuel is directly injected into a cylinder via injection means such as an electronically controlled injector. However, as long as a part of the fuel is injected under the form of direct injection, the internal combustion engine according to the present invention may be provided with injection means for injecting fuel into the intake port. That is, the internal combustion engine according to the present invention may be a so-called dual injection internal combustion engine.

  The engine 300 burns the air-fuel mixture through an ignition operation by an ignition device 200 in which a part of an ignition plug (not shown) is exposed in a combustion chamber in the cylinder 301, and is generated according to the explosion force caused by the combustion. The reciprocating motion of the piston 303 can be converted into the rotational motion of the crankshaft 305 via the connecting rod 304.

  In the vicinity of the crankshaft 305, a crank position sensor 306 that detects the rotational position (ie, crank angle) of the crankshaft 305 is installed. The crank position sensor 306 is electrically connected to the ECU 100 (not shown), and the ECU 100 calculates the rotational speed of the engine 300 based on the crank angle signal output from the crank position sensor 306. It has become.

  The engine 300 is an in-line four-cylinder engine in which four cylinders 301 are arranged in series in a direction perpendicular to the paper surface. However, since the configurations of the individual cylinders 301 are equal to each other, in FIG. Only the cylinder 301 will be described. Further, the number of cylinders and the arrangement form of each cylinder in the internal combustion engine according to the present invention are not limited to those of the engine 300, and may be, for example, a 6-cylinder, 8-cylinder, or 12-cylinder engine, V-type, horizontal It may be a facing type or the like, and can take various forms.

  In the engine 300, air sucked from the outside passes through the intake pipe 307 and is guided into the cylinder 301 through the intake port 310 when the intake valve 311 is opened. On the other hand, the fuel injection valve in the injector 312 is exposed in the cylinder interior 301, so that fuel can be directly injected into the cylinder. The fuel injected from the injector 312 is mixed with the intake air sucked when the intake valve 311 is opened, and becomes the above-described mixture.

  The fuel is stored in a fuel tank (not shown), and is supplied to a high pressure pump (not shown) via a delivery pipe (not shown) by the action of a feed pump (not shown). The high-pressure pump pumps and supplies this fuel to a common rail (not shown) that is shared by each cylinder and configured to be able to store the fuel in a high-pressure state. An injector 312 corresponding to each cylinder 301 is connected to the common rail, and fuel is directly injected into the cylinder 301 in each cylinder 301.

  The ignition device 200 having an ignition plug is disposed in the upper part of the combustion chamber 330 so that the electrode faces the combustion chamber 230, and when a required discharge voltage is applied to the ignition electrode, a spark is blown. Thereby, the mixed gas burns. In particular, the spark plug has a so-called ion current sensor capable of detecting an ion current. The ion current sensor is, for example, an ion current detection circuit, and more specifically includes a Zener diode, a capacitor, an ion current detection resistor, an inverting amplification circuit, and the like. The ion current sensor and the ECU constitute “misfire identification means” and “identification means” according to the present invention. The combustion chamber 330 is a space above the piston 303 inside the cylinder. The piston 303 reciprocates in the cylinder along with the combustion in the combustion chamber 330. That is, the volume of the combustion chamber 330 and the pressure in the cylinder change according to the position of the piston 303. The in-cylinder pressure sensor 332 detects the pressure in the cylinder. The reciprocating motion of the piston 303 is converted into the rotational motion of the crankshaft 305 via the connection rod 304, and this becomes the output of the engine 300. The in-cylinder pressure sensor 332 constitutes “misfire identification means” and “identification means” according to the present invention.

  The air-fuel mixture burned in the cylinder 301 becomes exhaust gas, and is led to the exhaust pipe 315 via the exhaust port 314 when the exhaust valve 313 that opens and closes in conjunction with opening and closing of the intake valve 311 is opened.

  On the other hand, on the upstream side of the intake port 310 in the intake pipe 307, a throttle valve 308 for adjusting the amount of intake air related to the intake air guided through a cleaner (not shown) is disposed. The throttle valve 308 is configured such that its drive state is controlled by a throttle valve motor 309 electrically connected to the ECU 100. The ECU 100 basically controls the throttle valve motor 309 so as to obtain a throttle opening corresponding to the accelerator opening, but without the driver's intention through the operation control of the throttle valve motor 309. It is also possible to adjust the throttle opening. That is, the throttle valve 308 is configured as a kind of electronically controlled throttle valve.

  A three-way catalyst 316 is installed in the exhaust pipe 315. The three-way catalyst 316 is a catalyst capable of purifying CO (carbon monoxide), HC (hydrocarbon), and NOx (nitrogen oxide) discharged from the engine 300, respectively. In addition, the form which a catalyst apparatus can take is not limited to a three-way catalyst, For example, instead of or in addition to a three-way catalyst, various catalysts such as an NSR catalyst (NOx storage reduction catalyst) or an oxidation catalyst may be installed.

  Further, the exhaust pipe 315 is provided with an exhaust sensor 317 configured to detect an air-fuel ratio of the exhaust of the engine 300, for example, a component of exhaust such as oxygen, carbon monoxide, and hydrocarbons. The exhaust sensor 317 constitutes the “misfire identification means” according to the present invention. Further, the water jacket installed in the cylinder block that accommodates the cylinder 301 is provided with a water temperature sensor 318 for detecting the cooling water temperature related to the cooling water (LLC) that is circulated and supplied to cool the engine 300. ing. The water temperature sensor 318 is electrically connected to the ECU 100, and the detected cooling water temperature is grasped by the ECU 100 at a constant or indefinite detection cycle.

  The exhaust pipe 315 and its surroundings are equipped with the following devices. The exhaust valve 313 is opened in the exhaust stroke, closed in other compression, combustion, and intake strokes, and exhaust is appropriately discharged from the combustion chamber 330. An exhaust gas recirculation (EGR) device 329 circulates part of the exhaust gas to the intake pipe 307 via the EGR pipe 333. This ring flow rate (that is, EGR amount) is adjusted according to the opening degree of an EGR valve (not shown) installed in the EGR pipe 333 in the pipeline. An EGR valve opening sensor (not shown) detects the opening of the EGR valve or the EGR amount.

  Here, in the internal combustion engine according to the present invention, for example, for the purpose of preventing direct contact between physical or mechanical components in the internal combustion engine or preventing seizure of the components, for example, Discharge means that is temporarily stored in an oil pan or the like installed below a cylinder block that accommodates the cylinder 301, for example, lubricating oil such as engine oil can take various forms such as electric drive type or mechanical drive type, Alternatively, it is configured to be circulated and supplied, for example, in a circulation path that is physically or mechanically constructed in advance by the action of the circulation means as a concept that may appropriately include suction means such as an oil strainer.

  For example, an intake valve system and an exhaust valve system that drive the intake valve 308 and the exhaust valve 311 and can include, for example, an intake cam, an intake camshaft, an exhaust cam and an exhaust camshaft (both of which are omitted in the reference numerals) It is accommodated in a metal cylinder head located at the top. Engine oil is circulated and supplied to these intake valve system and exhaust valve system housed in the cylinder head so that the operation of each part is lubricated and seizure prevention is achieved. Also, in the cylinder 301, for example, in order to facilitate sliding between the crankshaft 305, the connecting rod 304 and the piston 303, and further between the piston 303 and the inner wall (ie, the bore) of the cylinder 301, Oil is circulated and supplied, so that the operation is lubricated and each part is prevented from being seized.

  On the other hand, the engine oil circulated and supplied to each part of the engine 300 is temporarily stored in an oil pan installed below the cylinder block. The oil pan is provided with a circulation device (not shown) including an electric oil pump as an electrically driven pump, and the engine oil stored in the oil pan is described above via a circulation supply path (not shown). It is configured to be able to circulate and supply various target parts. The electric oil pump is electrically connected to the ECU 100, and the driving state is controlled by the control of the ECU 100. The engine oil circulation mode is not limited to that of the present embodiment as long as the operation of each part in the engine 300 can be lubricated and seizure prevention can be achieved, and various modes may be adopted.

(Basic configuration of ignition device)
Next, with reference to FIG.2 and FIG.3, the basic composition of the ignition device which concerns on this embodiment is demonstrated. FIG. 2 is a block diagram schematically showing the basic configuration of the ignition device according to this embodiment. In FIG. 2, the same parts as those in FIG. 1 described above are denoted by the same reference numerals, and the description thereof is omitted as appropriate. FIG. 3 is a block diagram schematically showing the basic configuration of the coil section in the ignition device according to the present embodiment.

  As shown in FIG. 2, the ignition device 200 according to the present embodiment includes coil portions (so-called coil packages) 210a, 210b, 210c, 210d, switch elements (so-called switching elements) 220a, 220b, 220c, 220d, And it is provided with spark plugs 230a, 230b, 230c, and 230d. The switch element according to the present embodiment is configured by, for example, a transistor, and is configured to be able to realize an action of flowing an electric current of an electronic circuit or not flowing an electric current, a so-called switch action.

  When the mixture in the combustion chamber of the cylinder (# 1) 21a is ignited under the control of the ECU 100, first, the ECU 100 coils an ignition signal IG for burning the mixture in the combustion chamber of the cylinder (# 1) 21a. Output to the unit 210a. At the same time or before and after, the ECU 100 outputs a switch signal SW for allowing the flow of a secondary current (hereinafter, appropriately referred to as a current) from the coil unit 210a to the spark plug 230a toward the switch element 220a. Next, when the switch signal SW is input to the switch element 220a, the switch element 220a actually causes the current generated in the coil part 210a to flow toward the spark plug 230a. In response to this current, a spark is generated in the spark plug 230a, and the air-fuel mixture in the combustion chamber of the cylinder (# 1) 21a is combusted.

  More specifically, as shown in FIG. 3, the coil unit 210a includes a transistor 211a, a primary side coil 212a, a secondary side coil 213a, and a diode 214a. Typically, a diode 214a and a high voltage diode are preferable. Thereby, the backflow of the secondary current can be effectively prevented.

  When the ignition signal IG is output from the ECU 100 toward the transistor 211a, a current flows through the primary coil 212a and a high voltage is generated at the secondary coil 213a. The switch element 220a ignites the high voltage generated in the secondary coil 213a in response to the switch signal SW that allows the current flow from the secondary coil 213a of the coil part 210a to the spark plug 230a and the application of voltage. The plug 230a is actually applied. In response to the applied high voltage, a discharge spark is generated in the discharge gap Gap of the spark plug 230a, and the air-fuel mixture in the combustion chamber of the cylinder (# 1) 21a burns.

  In a similar manner, when the mixture in the combustion chamber of the cylinder (# 2) 21b is ignited under the control of the ECU 100, first, the ECU 100 burns the mixture in the combustion chamber of the cylinder (# 2) 21b. The ignition signal IG is output toward the coil part 210b. At the same time or before and after, the ECU 100 outputs a switch signal SW that allows a current flow from the coil part 210b to the spark plug 230b to the switch element 220b. Next, when the switch signal SW is input to the switch element 220b, the switch element 220b actually causes the current generated in the coil portion 210b to flow toward the spark plug 230b. In response to this current, a spark is generated in the spark plug 230b, and the air-fuel mixture in the combustion chamber of the cylinder (# 2) 21b is combusted.

  More specifically, as shown in FIG. 3, the coil unit 210b includes a transistor 211b, a primary side coil 212b, a secondary side coil 213b, and a diode 214b.

  When the ignition signal IG is output from the ECU 100 to the transistor 211b, a current flows through the primary side coil 212b and a high voltage is generated at the secondary side coil 213b. The switch element 220b ignites the high voltage generated in the secondary coil 213b in response to the switch signal SW that permits the current flow from the secondary coil 213b of the coil part 210b to the ignition plug 230b and the application of voltage. The plug 230b is actually applied. In response to the applied high voltage, a discharge spark is generated in the discharge gap Gap of the spark plug 230b, and the air-fuel mixture in the combustion chamber of the cylinder (# 2) 21b burns.

  Note that the case of igniting the air-fuel mixture in the combustion chambers of the cylinder (# 3) 21c and the cylinder (# 4) 21d is substantially the same as the cylinder (# 1) 21a and the cylinder (# 2) 21b described above. Omitted.

  In particular, the switch elements 220a, 220b, 220c, and 220d according to the present embodiment can change the flow paths of currents that flow from the coil portions 210a, 210b, 210c, and 210d toward the spark plugs 230a, 230b, 230c, and 230d, respectively. It is configured to be. Next, the operating principle of these switch elements will be described.

(Switch element)
Here, with reference to FIG. 4, the operation principle of the switch elements 220a, 220b, 220c, and 220d according to the present embodiment will be described. FIG. 4 is a table conceptually showing the type of operation of the switch element according to the present embodiment.

  As shown in FIG. 4, there are three types of operation of the switch element.

  That is, the operation of the first type of switch element is a “type A” operation in which a current flows from one coil portion toward a spark plug that serves as a reference for the one coil portion. Here, the “reference spark plug” according to the present embodiment means a spark plug that has one-to-one correspondence with one coil portion with the highest priority. Typically, as shown in FIGS. 2 and 3 described above, the spark plug has the highest priority (in other words, in principle, in principle, the default) in the coil portion 210a. 230a is associated with one to one. The spark plug 230b is associated with the coil part 210b on a one-to-one basis with the highest priority. The spark plug 230c is associated with the coil part 210c on a one-to-one basis with the highest priority. The spark plug 230d is associated with the coil portion 210d on a one-to-one basis with the highest priority. However, the coil portion can also flow current to other spark plugs except for the reference spark plug, secondarily (in other words, exceptionally).

  Specifically, as shown in “Type A” in FIG. 4, in the switch element, a switch signal that permits the flow of current from the current input port Pi to the output port Po (hereinafter, as appropriate, In response to this switch signal (referred to as “switch signal SWA”), current actually flows from the input port Pi to the output port Po. In particular, the current input port Pi of the switch element is connected to one coil part, and the current output port Po of the switch element is one spark plug corresponding to one coil part, that is, one coil. It is connected to a spark plug which is a reference for the part.

  The operation of the second type of switch element is a “type B” operation in which a current is passed from one coil portion to another spark plug other than the spark plug serving as a reference for the one coil portion. Specifically, as shown in “Type B” in FIG. 4, in the switch element, the flow of current from the current input port Pi to the output port Po is prohibited, and in the switch element, In response to a switch signal that permits the flow of current from the input port Pi to the shared port Ps (hereinafter, this switch signal is referred to as “switch signal SWB” as appropriate), the input port Pi actually transfers to the shared port Ps. Current flows. Here, the “switch element sharing port Ps” according to the present embodiment means a current flow path for mutually transferring current between the switch elements 220a, 220b, 220c, and 220d. That is, one switch element can pass a current input to one switch element itself toward another switch element other than the one switch element via the shared port Ps. In addition, one switch element can flow the current flowing through the other switch elements except the one switch element toward the output port Po of the one switch element via the shared port Ps.

  The operation of the third type of switching element is not only to allow a current to flow from one coil part toward a reference spark plug for one coil part, but also from one coil part to another coil part. This is a “type C” operation in which a current flows toward a spark plug that serves as a reference for the coil section. Specifically, as shown in “type C” in FIG. 4, in the switch element, the current flow from the current input port Pi to the output port Po is permitted, and in the switch element, In response to a switch signal that permits a current flow from the common port Ps to the input port Pi (hereinafter, this switch signal is referred to as “switch signal SWC” as appropriate), the input port Pi is actually connected to the output port Po. As current flows, current actually flows from the shared port Ps to the output port Po.

(Specific example of current transfer operation between multi-cylinder switch elements)
Next, with reference to FIG. 5, a specific example of the current transfer operation between the four switch elements corresponding to the four cylinders according to the present embodiment will be described. FIG. 5 is a diagram (FIG. 5A) schematically showing the ignition timing in the four cylinders according to the present embodiment, and a table conceptually showing types of operation of the switch elements (FIG. 5). 5 (b)). In FIG. 5A, the black star indicates the time when the air-fuel mixture is actually ignited, and the white star supplies current from one coil to another spark plug. Indicates the time. FIG. 5 shows a four-cylinder engine that includes one ignition plug for each cylinder and a coil portion having a coil as described in FIGS. 2 and 3 described above. Further, the order of ignition on the time axis is cylinder # 1, cylinder # 3, cylinder # 4, and cylinder # 2.

  As shown in FIG. 5A, in the present embodiment, the current generated in the coil portion of the cylinder in the expansion stroke and the coil portion of the cylinder in the exhaust stroke is supplied so as to be supplied to the cylinder in the compression stroke. That is, in order to ignite the air-fuel mixture in the compression stroke of the cylinder (# 1), in addition to the current from the coil part 210a of the cylinder (# 1), the coil part 210b and the cylinder (# 4) of the cylinder (# 2) ) From the coil portion 210d through the switch elements 220a, 220b, and 220d to the spark plug 230a. Specifically, as shown in FIG. 5B, the switch element 220a of the cylinder (# 1) is changed from the one coil unit 210a to the one coil unit 210a in accordance with the switch signal SWC described above. In addition to flowing current toward the spark plug 230a, the other coil portions 210b and 210d different from the one coil portion 210a flow current toward the reference spark plug 230a for the one coil portion 210a. Perform type C operation. Further, as shown in FIG. 5B, the switch element 220b of the cylinder (# 2) and the switch element 220d of the cylinder (# 4) are supplied from the coil portions 210b and 210d in accordance with the switch signal SWB described above. A “type B” operation is performed in which a current is supplied to the other spark plugs 230a except for the spark plugs 230b and 230d, which are the reference for the coil portions 210b and 210d. Note that it is preferable from the viewpoint of power saving that no current is generated in the coil portion 210c of the cylinder (# 3).

  In substantially the same manner, as shown in FIG. 5 (a), in order to ignite the air-fuel mixture in the compression stroke of the cylinder (# 3), in addition to the current from the coil portion 210c of the cylinder (# 3), Current from the coil part 210a of the cylinder (# 1) and the coil part 210b of the cylinder (# 2) is passed through the ignition plug 230c via the switch elements 220a, 220b, and 220c. Specifically, the switch element 220c of the cylinder (# 3) causes a current to flow from the one coil unit 210c toward the ignition plug 230c serving as a reference for the one coil unit 210c in accordance with the switch signal SWC described above. In addition, a “type C” operation is performed in which current flows from the other coil portions 210a and 210b different from the one coil portion 210c toward the spark plug 230c. Further, the switch element 220a of the cylinder (# 1) and the switch element 220b of the cylinder (# 2) are used as a reference for the coil parts 210a and 210b from the coil parts 210a and 210b in accordance with the switch signal SWB described above. A “type B” operation is performed in which a current is supplied to the other spark plugs 230c except for the spark plugs 230a and 230b. It is preferable from the viewpoint of power saving that no current is generated in the coil portion 210d of the cylinder (# 4).

  In substantially the same manner, as shown in FIG. 5A, in order to ignite the air-fuel mixture in the compression stroke of the cylinder (# 4), in addition to the current from the coil part 210d of the cylinder (# 4), Current from the coil part 210a of the cylinder (# 1) and the coil part 210c of the cylinder (# 3) is passed through the spark plug 230d via the switch elements 220a, 220b, and 220d. Specifically, the switch element 220d of the cylinder (# 4) performs a “type C” operation in accordance with the switch signal SWC described above. Further, the switch element 220a of the cylinder (# 1) and the switch element 220c of the cylinder (# 3) perform a “type B” operation in accordance with the switch signal SWB described above. It is preferable from the viewpoint of power saving that no current is generated in the coil part 210b of the cylinder (# 2).

  In substantially the same manner, as shown in FIG. 5 (a), in order to ignite the air-fuel mixture in the compression stroke of the cylinder (# 2), in addition to the current from the coil portion 210b of the cylinder (# 2), Current from the coil part 210c of the cylinder (# 3) and the coil part 210d of the cylinder (# 4) is passed through the spark plug 230b via the switch elements 220b, 220c and 220d. Specifically, the switch element 220b of the cylinder (# 2) performs the “type C” operation according to the switch signal SWC described above. Further, the switch element 220c of the cylinder (# 3) and the switch element 220d of the cylinder (# 4) perform a “type B” operation in accordance with the switch signal SWB described above. It is preferable from the viewpoint of power saving that no current is generated in the coil portion 210a of the cylinder (# 1).

  As described above, according to the present embodiment, the output lines from which the secondary currents are output from the plurality of coils are connected via the high-breakdown-voltage switch elements, and each of the plurality of spark plugs has an arbitrary spark plug. Secondary current from a plurality of coils can be supplied.

  As a result, the current generated in each of the plurality of coil portions is simultaneously supplied to one spark plug, so that the level of the discharge current can be increased and the air-fuel mixture can be ignited with a higher discharge voltage. Thereby, larger flame nuclei can be grown in the combustion chamber, and more powerful flame nuclei can be formed. Thereby, the air-fuel mixture in the combustion chamber can be burned more efficiently.

  In addition, the current generated in each of the plurality of coil portions is supplied to one spark plug at different times, so that the time interval during which the spark plug is discharged can be lengthened. As a result, the air-fuel mixture in the combustion chamber can be burned more reliably with little or no possibility of misfire.

(Discharge pattern and its effect)
Here, with reference to FIG. 6, the pattern of the discharge state of the ignition plug which concerns on this embodiment is demonstrated. Here, FIG. 6 is a table showing the change over time in the discharge current as a factor, the effect, and the operation region to be applied in the discharge state pattern of the spark plug according to the present embodiment. In addition, the vertical axis | shaft of the graph in FIG. 6 shows the magnitude | size of an electric current, and a horizontal axis shows time. Further, time flows from time t1 to time t3 in FIG. That is, time t3 indicates the past from time t2, and time t2 indicates the past from time t1. In the present embodiment, it is assumed that the plurality of types of operation regions uniquely correspond to the plurality of types of operation states.

  As shown in FIG. 6, the discharge state patterns typically include a “single discharge pattern”, a “current enhancement pattern”, a “current enhancement and discharge time extension pattern”, and a “multiple discharge pattern (ie, 4 types of discharge time extension patterns) ”. For the sake of simplicity, hereinafter, in order to ignite the air-fuel mixture in the compression stroke of the cylinder (# 1) in FIG. 5 (a) described above, from the coil portion 210a of the cylinder (# 1), In addition to the current, the current from the coil part 210b of the cylinder (# 2) and the coil part 210d of the cylinder (# 4) can be supplied to the spark plug 230a via the switch elements 220a, 220b, 220d. I will explain.

  The “single discharge pattern” means a normal discharge state, and the current generated in the coil part 210a is supplied to the spark plug 230a serving as a reference for the coil part 210a. That is, as shown in the column of “coil of interest” in FIG. 6, the current generated in the coil section 210 a rapidly increases at time t <b> 1 and then decreases with time. Further, as shown in the column “Current from Other Coil (No. 1)” in FIG. 6, no current is generated in the coil portion 210b different from the coil portion 210a, and therefore, it is not supplied to the spark plug 230a. Further, as shown in the column of “current from other coil (part 2)” in FIG. 6, no current is generated in the coil part 210d different from the coil part 210a, and therefore, it is not supplied to the spark plug 230a. Thereby, as shown in the column “Discharge current at the plug of interest” in FIG. 6, the discharge current at the spark plug 230a has a shape substantially equal to the current generated at the coil portion 210a. Thereby, as shown in the column of “Effect” in FIG. 6, the amount of current required for ignition of the air-fuel mixture as compared with the case where the coil portion 210 b and the coil portion 210 d are different from the coil portion 210 a. Therefore, it is possible to realize power saving, and consequently to improve the energy efficiency of the vehicle. Such a “single discharge pattern”, as shown in the “operating region” column in FIG. 6, is an operating region (so-called warm stoichiometric) that approaches the ideal air-fuel ratio when the engine temperature is higher than a predetermined threshold. It has been proved by research by the present inventor that it is suitable in the operation region of the present invention. Here, the predetermined threshold value according to the present embodiment may typically mean an engine temperature that maximizes the thermal efficiency of the engine.

  In the “current enhancement pattern”, all the currents generated in the coil portions 210a, 210b, and 210d are simultaneously supplied to one spark plug 230a. The “simultaneous” constitutes one specific example of “predetermined timing” according to the present invention. That is, as shown in the column of “coil of interest” in FIG. 6, the current generated in the coil section 210 a rapidly increases at time t <b> 1 and then decreases with time. Further, as shown in the column “Current from other coils (part 1)” in FIG. 6, the current generated in the coil portion 210 b rapidly increases at time t <b> 1 and then decreases with time. The current generated in the coil part 210b is supplied to the spark plug 230a. Further, as shown in the column “Current from other coils (No. 2)” in FIG. 6, the current generated in the coil section 210 d rapidly increases at time t <b> 1 and then decreases with time. The current generated in the coil part 210d is supplied to the spark plug 230a. As a result, as shown in the column “Discharge current at the plug of interest” in FIG. 6, the discharge current at the spark plug 230a rapidly increases at time t1, and the current level is generated at the coil section 210a. The current rises up to about 3 times the current. Thereby, as shown in the column of “Effect” in FIG. 6, larger flame nuclei can be grown in the combustion chamber to form stronger flame nuclei. Thereby, the air-fuel mixture in the combustion chamber can be burned more efficiently. Such a “current enhancement pattern”, as shown in the “operating region” column in FIG. 6, is an ideal air condition when the operating region during EGR, the air lean burn operating region, and the engine temperature are low. According to the inventor of the present application, the present invention is suitable for an operation region close to the fuel ratio (so-called cold stoichiometric operation region), an operation region where the engine is started at a low engine temperature (so-called cold start operation region). It has been found by research.

  The “multiple discharge pattern (ie, discharge time extension pattern)” supplies the current generated in each of the coil portions 210a, 210b, and 210d to the spark plug 230a at different timings. The “different timing” constitutes another specific example of the “predetermined timing” according to the present invention. That is, as shown in the column of “coil of interest” in FIG. 6, the current generated in the coil section 210 a rapidly increases at time t <b> 1 and then decreases with time. Further, as shown in the column “Current from other coils (part 1)” in FIG. 6, the current generated in the coil portion 210 b rapidly increases at time t <b> 2 and then decreases with time. The current generated in the coil part 210b is supplied to the spark plug 230a. Further, as shown in the column “Current from other coils (No. 2)” in FIG. 6, the current generated in the coil section 210 d rapidly increases at time t <b> 3 and then decreases with time. The current generated in the coil part 210d is supplied to the spark plug 230a. As a result, as shown in the column “Discharge current at the plug of interest” in FIG. 6, the discharge current at the spark plug 230a rapidly increases at time t1, and then decreases with time. Then, it rises rapidly again at time t2, then falls with the passage of time, rises again suddenly at time t3, and then falls with the passage of time. As a result, as shown in the column “Effect” in FIG. 6, the time interval during which the spark plug 230a is discharged can be made longer than the “single discharge pattern”. As a result, the air-fuel mixture in the combustion chamber can be burned more reliably with little or no possibility of misfire. That is, the reliability of ignition of the air-fuel mixture can be further improved. Such a “multiple discharge pattern (that is, an extended discharge time pattern)” is suitable, for example, in the operation region of stratified combustion in a direct injection engine, as shown in the column of “operation region” in FIG. It has been proved by research by the present inventor. The discharging time interval is limited to the operation of the switch element described above. That is, the discharging time interval can be extended to the time when the air-fuel mixture is ignited in the cylinder that is scheduled to be ignited in the next compression stroke.

  The “current enhancement and discharge time extension pattern” is a compromise pattern of the “current enhancement pattern” described above and the “multiple discharge pattern (ie, discharge time extension pattern)” described above. That is, the current generated in each of the coil portions 210a and 210b is simultaneously supplied to the spark plug 230a. At the same time, the current generated in the coil part 210d is supplied to the spark plug 230a at a timing different from that of the coil parts 210a and 210b. That is, as shown in the column of “coil of interest” in FIG. 6, the current generated in the coil section 210 a rapidly increases at time t <b> 1 and then decreases with time. Further, as shown in the column “Current from other coils (part 1)” in FIG. 6, the current generated in the coil portion 210 b rapidly increases at time t <b> 1 and then decreases with time. The current generated in the coil part 210b is supplied to the spark plug 230a. Further, as shown in the column “Current from other coils (No. 2)” in FIG. 6, the current generated in the coil part 210 d increases rapidly at time t <b> 2 and then decreases with time. The current generated in the coil part 210d is supplied to the spark plug 230a. As a result, as shown in the column “Discharge current at the plug of interest” in FIG. 6, the discharge current at the spark plug 230a rapidly increases at time t1, and the current level is generated at the coil section 210a. The current rises to about twice the current. Thereafter, it decreases with the passage of time, rapidly increases again at time t2, and then decreases with the passage of time. Thereby, as shown in the column of “Effect” in FIG. 6, larger flame nuclei can be grown in the combustion chamber to form stronger flame nuclei. Thereby, the air-fuel mixture in the combustion chamber can be burned more efficiently. Such “current enhancement and discharge time extension pattern” includes, as shown in the “operating region” column in FIG. 6, the operating region when performing EGR, the operating region when performing air lean burn, the engine It is suitable in an operating range (so-called cold stoichiometric operating range) approaching the ideal air-fuel ratio in a low temperature state and an operating region (so-called cold starting operating range) in which the engine is started at a low engine temperature. It has been proved by research by the present inventor.

  As a result of the above, an infinite number of discharge patterns can be realized by changing the three parameters of the coil portion that supplies current to the spark plug of interest, the number of the coil portions, and the supply timing. By implementing these multiple discharge patterns according to the operation areas of a plurality of types of engines, the air-fuel mixture can be combusted more appropriately and reliably in the combustion chamber in an appropriate manner corresponding to the operation areas of the engine. Is possible.

  In particular, the ignition device having a simple and low-cost configuration is very useful because the discharge state pattern can be arbitrarily changed.

(Second Embodiment)
(Basic configuration of ignition device)
Next, with reference to FIG.7 and FIG.8, the basic composition of the ignition device which concerns on 2nd Embodiment is demonstrated. FIG. 7 is a block diagram schematically showing the basic configuration of the ignition device according to the second embodiment. In FIG. 7, the same reference numerals are given to the same portions as those in FIG. 2 described above, and the description thereof will be omitted as appropriate. In addition, black circles in FIG. 7 indicate that two intersecting wirings are electrically connected. FIG. 8 is a table showing combinations of spark plugs that actually perform ignition in the ignition device according to the second embodiment and the number of coil portions that are sources of supplying current to the spark plugs.

  As shown in FIG. 7, the ignition device 200A according to the second embodiment includes coil portions 210a1, 210a2, 210a3, switch elements 220a1, 220a2, 220a3, and spark plugs 230a1, 230a2 in the cylinder (# 1) 21a. , 230a3. In particular, in the second embodiment, the other cylinders (# 2), the cylinders (# 3), and the cylinders (# 4) have substantially the same configuration, and thus the description thereof is omitted.

  When the mixture in the combustion chamber of the cylinder (# 1) 21a is ignited by the spark plug 230a1 under the control of the ECU 100, first, the ECU 100 performs ignition for burning the mixture in the combustion chamber of the cylinder (# 1) 21a. The signal IG is output toward the coil part 210a1. At the same time or before and after, the ECU 100 outputs a switch signal SW for allowing a current flow from the coil portion 210a1 to the spark plug 230a1 to the switch element 220a1. Next, when the switch signal SW is input to the switch element 220a1, the switch element 220a1 actually causes the current generated in the coil part 210a1 to flow toward the spark plug 230a1. In response to this current, a spark is generated in the spark plug 230a1, and the air-fuel mixture in the combustion chamber of the cylinder (# 1) 21a is combusted.

  In a similar manner, when the air-fuel mixture in the combustion chamber of the cylinder (# 1) 21a is ignited by the spark plug 230a2 under the control of the ECU 100, the ECU 100 first converts the air-fuel mixture in the combustion chamber of the cylinder (# 1) 21a. An ignition signal IG for burning is output toward the coil part 210a2. At the same time or before and after, the ECU 100 outputs a switch signal SW that allows a current flow from the coil portion 210a2 to the spark plug 230a2 to the switch element 220a2. Next, when this switch signal SW is input to the switch element 220a2, the switch element 220a2 actually causes the current generated in the coil part 210a2 to flow toward the spark plug 230a2. In response to this current, a spark is generated in the spark plug 230a2, and the air-fuel mixture in the combustion chamber of the cylinder (# 1) 21a is combusted.

  In a similar manner, when the air-fuel mixture in the combustion chamber of the cylinder (# 1) 21a is ignited by the spark plug 230a3 under the control of the ECU 100, the ECU 100 first converts the air-fuel mixture in the combustion chamber of the cylinder (# 1) 21a. An ignition signal IG for burning is output toward the coil part 210a3. At the same time or before and after, the ECU 100 outputs a switch signal SW that allows a current flow from the coil portion 210a3 to the spark plug 230a3 toward the switch element 220a3. Next, when the switch signal SW is input to the switch element 220a3, the switch element 220a3 actually causes the current generated in the coil part 210a3 to flow toward the spark plug 230a3. In response to this current, a spark is generated in the spark plug 230a3, and the air-fuel mixture in the combustion chamber of the cylinder (# 1) 21a is combusted.

  In particular, in the second embodiment, the switch elements 220a1, 220a2, and 220a3 include the “type A” according to the switch signal SWA described above, the “type B” according to the switch signal SWB described above, and the switch signal SWC described above. The operation of “type C” according to the above can be performed. Specifically, as indicated by an arrow AR1 in FIG. 8, the supply source for supplying current to the spark plug 230a1 is “two” of the coil portions 210a1 and 210a2, and the current is supplied to the spark plug 230a3. A combination is possible in which the source is “one” of the coil part 210a3 and “0” is assumed without the supply source supplying current to the spark plug 230a2.

  In this case, the switching element 220a1 causes the one coil portion to flow from one coil portion 210a1 toward the spark plug 230a1 serving as a reference for the one coil portion 210a1 in accordance with the switch signal SWC described above. A “type C” operation is performed in which current flows from another coil portion 210a2 different from the portion 210a1 toward the spark plug 230a1. In addition, the switch element 220a2 performs a “type B” operation in which a current flows from the coil unit 210a2 to the spark plug 230a1 in accordance with the switch signal SWB described above. Further, the switch element 220a3 performs a “type A” operation in which a current flows from the coil unit 210a3 to the spark plug 230a3 in accordance with the switch signal SWA described above.

  In this way, by changing the two parameters of the coil part that supplies current to the spark plug of interest and the number of the coil parts, as shown in FIG. 8, for example, innumerable combinations of “16” or more Can think. Furthermore, in addition to these two parameters, an infinite number of discharge patterns can theoretically be realized by changing a parameter called current supply timing.

  As a result, the current generated in each of the plurality of coil portions 210a1, 210a2, 210a3 in the single cylinder (# 1) 21a is simultaneously supplied to one spark plug, so that the level of the discharge current is increased. The air-fuel mixture can be ignited with a high discharge voltage. Thereby, larger flame nuclei can be grown in the combustion chamber, and more powerful flame nuclei can be formed. Thereby, the air-fuel mixture in the combustion chamber in one cylinder can be burned more efficiently.

  In addition, the current generated in each of the plurality of coil portions 210a1, 210a2, and 210a3 in the single cylinder (# 1) 21a is supplied to one spark plug at different times, so that the spark plug is discharged. The time interval can be lengthened. As a result, the air-fuel mixture in the combustion chamber in one cylinder can be burned more reliably with little or no possibility of misfire.

(Third embodiment)
(Basic configuration of ignition device)
Next, with reference to FIG.9 and FIG.10, the basic composition of the ignition device which concerns on 3rd Embodiment is demonstrated. FIG. 9 is a block diagram schematically showing the basic configuration of the ignition device according to the third embodiment. In FIG. 9, the same reference numerals are given to the same portions as those in FIG. 2 or 7 described above, and the description thereof will be omitted as appropriate. Further, black circles in FIG. 9 indicate that two intersecting wirings are electrically connected. FIG. 10 is a table showing combinations of spark plugs that actually perform ignition in the ignition device according to the third embodiment and the number of coil portions that are sources of supplying current to the spark plugs.

  As shown in FIG. 9, the ignition device 200B according to the third embodiment includes, in the cylinder (# 1) 21a, coil portions 210a1, 210a2, 210a3, switch elements 220a1, 220a2, 220a3, 220ab1, 220ab2, 220ab3, and The spark plugs 230a1, 230a2, and 230a3 are provided. In addition, the ignition device 200B according to the third embodiment includes a coil portion 210b1, 210b2, 210b3, switch elements 220b1, 220b2, 220b3, 220ba1, 220ba2, 220ba3, and an ignition plug 230b1, in the cylinder (# 1) 21b. 230b2 and 230b3 are provided.

  In particular, the switch elements 220ab1, 220ab2, 220ab3 and the switch elements 220ba1, 220ba2, 220ba3 are electrically connected so as to be able to exchange current.

  In particular, in the third embodiment, the other cylinders (# 3) and the cylinder (# 4) have substantially the same configuration, and thus the description thereof is omitted.

  When the mixture in the combustion chamber of the cylinder (# 1) 21a is ignited by the spark plug 230a1 under the control of the ECU 100, first, the ECU 100 performs ignition for burning the mixture in the combustion chamber of the cylinder (# 1) 21a. The signal IG is output toward the coil part 210a1. At the same time or before and after, ECU 100 outputs a switch signal SW for allowing a current flow from coil section 210a1 to spark plug 230a1 to switch elements 220a1 and 220ab1. Next, when the switch signal SW is input to the switch elements 220a1 and 220ab1, the switch elements 220a1 and 220ab1 actually flow the current generated in the coil part 210a1 toward the spark plug 230a1. In response to this current, a spark is generated in the spark plug 230a1, and the air-fuel mixture in the combustion chamber of the cylinder (# 1) 21a is combusted. The operations of the coil portion 210a2 and the switch elements 220a2 and ab2 when ignited by the spark plug 230a2 and the operations of the coil portion 210a3 and the switch elements 220a3 and ab3 when ignited by the spark plug 230a3 are substantially the same. Since there is, explanation is omitted.

  In particular, in the third embodiment, the switch elements 220a1, 220a2, 220a3, 220ab1, 220ab2, 220ab3, and the switch elements 220b1, 220b2, 220b3, 220ba1, 220ba2, 220ba3 are “type A” according to the switch signal SWA described above. The operation of “type B” according to the above-described switch signal SWB and “type C” according to the above-described switch signal SWC can be performed. Specifically, as indicated by an arrow AR2 in FIG. 10, the supply source for supplying current to the spark plug 230a1 is “five” of the coil portions 210a1, 210a2, 210b1, 210b2, and b3, and the spark plug 230a3. The supply source for supplying current to the coil portion 210a3 may be “one”, and the supply source for supplying current to the spark plugs 230a2, 210b1, 210b2, and b3 may be “0”. For example, if each of the four cylinders has three coil portions, current can be supplied from a maximum of 12 (= 1 + 2 + other cylinder = 1 + 2 + 3 × 3) coil portions toward one spark plug. Is noted.

  Again, in the case of the combination indicated by the arrow AR2 in FIG. 10, the switch element 220a1 has a coil in addition to flowing a current from the coil section 210a1 toward the switch element 220ab1 in accordance with the switch signal SWC described above. A “type C” operation is performed in which current flows from another coil part 210a2 different from the part 210a1 toward the switch element 220ab1. In addition, the switch element 220b1 switches from other coil parts 210b2 and 210b3 different from the coil part 210b1 in addition to flowing current from the coil part 210b1 to the switch element 220ba1 in accordance with the switch signal SWC described above. A “type C” operation is performed in which a current flows toward the element 220ba1. The switch element 220ba1 performs a “type B” operation in which a current generated in the coil portions 210b1, 210b2, and 210b3 flows toward the switch element 220ab1. The switch element 220ab1 performs a “type C” operation in which current generated in the coil portions 210b1, 210b2, and 210b3 is supplied to the spark plug 230a1 in addition to the coil portions 210a1 and a2.

  In addition, the switch element 220a2 performs a “type B” operation in which a current flows from the coil unit 210a2 to the switch element 220ab1 in accordance with the above-described switch signal SWB. Further, the switch elements 220b2 and 220b3 perform a “type B” operation in which a current flows from the coil units 210b2 and 210b3 to the switch element 220b1 in accordance with the above-described switch signal SWB.

  In addition, the switch element 220a3 performs a “type A” operation in which a current flows from the coil unit 210a3 to the switch element 220ab3 in accordance with the switch signal SWA described above.

  Further, the switch element 220ab3 performs a “type A” operation in which a current flows from the switch element 220a3 to the spark plug 230a3 in accordance with the above-described switch signal SWA.

  In this way, by changing the three parameters of the focused cylinder, the coil portion that supplies current to the focused spark plug, and the number of the coil portions, as shown in FIG. 10, for example, “26” Innumerable combinations of the above can be considered. Furthermore, in addition to these three parameters, an infinite number of discharge patterns can be theoretically realized by changing a parameter called current supply timing.

  As a result, the current generated in each of the plurality of coil portions 210a1, 210a2, 210a3, 210b1, 210b2, and 210b3 in the plurality of cylinders 21a and 21b is simultaneously supplied to one spark plug, thereby reducing the level of the discharge current. The mixture can be ignited at a higher and higher discharge voltage. Thereby, larger flame nuclei can be grown in the combustion chamber, and more powerful flame nuclei can be formed. Thereby, the air-fuel mixture in the combustion chamber in one cylinder can be burned more efficiently.

  In addition, the current generated in each of the plurality of coil portions 210a1, 210a2, 210a3, 210b1, 210b2, and 210b3 in the plurality of cylinders 21a and 21b is supplied to one spark plug at different times, so that the spark plug discharges. The time interval can be made longer. As a result, the air-fuel mixture in the combustion chamber in one cylinder can be burned more reliably with little or no possibility of misfire.

  As described above, typically, current input / output from other coils can be appropriately controlled. In addition, a secondary current output from a coil of another cylinder can be supplied to an arbitrary spark plug. In addition, a secondary current output from another coil in one cylinder can be supplied to an arbitrary spark plug.

(Fourth embodiment)
(Switching discharge pattern for each operation area)
Next, the principle of switching the discharge state pattern for each operation region according to the fourth embodiment will be described with reference to FIGS. 11 to 15. FIG. 11 is a graph schematically showing an operation region where the discharge state pattern according to the fourth embodiment is switched. In FIG. 11, the vertical axis represents engine torque (Nm: Newton · meter), and the horizontal axis represents engine rotation speed (rpm: revolution per minute). FIG. 12 is a cross-sectional view of a cylinder (FIG. 12A) schematically showing a state in the combustion chamber at the time of carrying out EGR or air lean burn according to the fourth embodiment, and the discharge state as a current. It is the graph (FIG.12 (b)) shown by the time change of. In addition, the dotted hatching in the combustion chamber in FIG. 12A indicates that the density of the air-fuel mixture is uniform in the combustion chamber. In addition, the vertical axis of the graph in FIG. 12B indicates the current magnitude, and the horizontal axis indicates time.

  FIG. 13 is a cross-sectional view (FIG. 13A) schematically showing the inside of the combustion chamber during stratified combustion according to the fourth embodiment (FIG. 13A), and a graph showing the discharge state as a function of time (FIG. 13). FIG. 13B). Note that the dotted hatching in the combustion chamber in FIG. 13A indicates that the density of the air-fuel mixture is high around the spark plug in the combustion chamber. In addition, the vertical axis of the graph in FIG. 13B indicates the magnitude of current, and the horizontal axis indicates time.

  As shown in FIG. 11, the operation region for switching the discharge state pattern according to the fourth embodiment includes quantitative parameters such as engine torque, engine rotation speed, engine (or engine coolant) temperature, and exhaust temperature. In addition, based on qualitative parameters such as the combustion state in the combustion chamber and the degree of occurrence of knocking, typically, it can be roughly divided into six operating regions. That is, in FIG. 11, “I” indicates an operation region in which stratified combustion is performed, and “II” is an operation in which the density of the air-fuel mixture in the combustion chamber is uniform during EGR or air lean burn. “III” indicates an operation region that is close to the ideal air-fuel ratio and is a partial load, “IV” indicates an operation region that is a high load or a full load, and “V” indicates a high exhaust temperature. , “VI” indicates an operation region where the engine temperature is lower than a predetermined temperature such as 40 ° C., that is, a so-called cold operation region. However, the operation region “VI” is an operation region excluding the operation region “V” which is a high load or a full load.

  In particular, as shown in FIG. 12 (a), in the operation region “II” where the density of the air-fuel mixture in the combustion chamber becomes uniform when EGR or air lean burn is performed, each of the plurality of coil portions is used. It is preferable to apply the “current enhancement pattern” described above with reference to FIG. 6 in which all generated currents are supplied simultaneously to one spark plug. That is, as shown in FIG. 12B, the discharge current at the spark plug rises rapidly, and the current level is a number based on the current generated in the conventional example to which the “current enhancement pattern” is not applied. It rises to double and then declines over time. Thereby, larger flame nuclei can be grown in the combustion chamber, and more powerful flame nuclei can be formed. Thereby, the air-fuel mixture in the combustion chamber can be burned more efficiently.

  In particular, as shown in FIG. 13A, in the operation region “I” where stratified combustion is performed, the current generated in each of the plurality of coil portions is supplied to one spark plug at different timings. It is preferable to apply the “multiple discharge pattern (that is, discharge time extension pattern)” described in FIG. That is, as shown in FIG. 13 (b), the discharge current at the spark plug rises rapidly, and then the discharge state of the conventional example in which the “multiple discharge pattern (that is, the extended discharge time pattern)” is not applied. It decreases with the passage of a longer time as compared with. As a result, the air-fuel mixture in the combustion chamber can be burned more reliably with little or no possibility of misfire. That is, the reliability of ignition of the air-fuel mixture can be further improved.

(Switching the discharge state pattern according to the number of spark plugs per cylinder)
Next, with reference to FIGS. 14 and 15, the principle of switching the discharge state pattern in accordance with the number of ignition plugs for each cylinder in addition to the operation region according to the fourth embodiment will be described. FIG. 14 is a table showing the operation region and the discharge state pattern in the case where each cylinder according to the fourth embodiment has one spark plug. FIG. 15 is a table showing a pattern of operation regions and discharge states when each cylinder according to the fourth embodiment has a plurality of spark plugs.

(When each cylinder has one spark plug)
As shown in FIG. 14, when each cylinder has one spark plug, in the operation region “I” where stratified combustion is performed, the “multiple discharge pattern (that is, the discharge time extension) described in FIG. It is preferable to apply the “pattern)”. Thereby, in the stratified combustion in which the distribution of the air-fuel mixture in the combustion chamber is likely to vary for each cycle of each cylinder, it is possible to lengthen the time interval at which ignition is possible. As a result, it is possible to increase the chance of ignition in stratified combustion and stabilize the combustion.

  Further, in the operation region “II” in which the density of the air-fuel mixture in the combustion chamber is uniform during the EGR or the air lean burn, the “current enhancement pattern” described in FIG. 6 may be applied. preferable. Thereby, larger flame nuclei can be grown in the combustion chamber, and more powerful flame nuclei can be formed. Thereby, the air-fuel mixture in the combustion chamber can be burned more efficiently.

  Further, it is preferable to apply the “single discharge pattern” described with reference to FIG. 6 in the operation region “III” which is close to the ideal air-fuel ratio and is a partial load. This is because in combustion at an ideal air-fuel ratio, sufficiently stable combustion can be secured with a relatively small current. This “single discharge pattern” eliminates the need to increase the amount of current required when the air-fuel mixture is ignited, thus realizing power savings and, in turn, improving the energy efficiency of the vehicle. .

  Moreover, in the operation region “IV” that is a high load or a full load, it is preferable to apply the “current enhancement pattern” described in FIG. This is because the airflow is stronger than in other operating areas, and thus effectively prevents the flame kernel from blowing off. With this “current enhancement pattern”, larger flame nuclei can be grown in the combustion chamber to form stronger flame nuclei. Thereby, the air-fuel mixture in the combustion chamber can be burned more efficiently.

  In the operation region “V” where the exhaust temperature is high and the degree of occurrence of knocking is high, it is preferable to apply the “single discharge pattern” described in FIG. This is because in this operating region, sufficiently stable combustion can be secured with a relatively small current. This “single discharge pattern” eliminates the need to increase the amount of current required when the air-fuel mixture is ignited, thus realizing power savings and, in turn, improving the energy efficiency of the vehicle. .

  Further, in the operation region (so-called cold operation region) “VI” where the engine temperature is lower than a predetermined temperature such as 40 ° C., for example, the “current enhancement pattern” described in FIG. 6 is applied. It is preferable. This is because in this operating region, only small flame nuclei can be formed, or the flame nuclei themselves are not generated, and the combustion state is unstable. With this “current enhancement pattern”, larger flame nuclei can be grown in the combustion chamber to form stronger flame nuclei. Thereby, the air-fuel mixture in the combustion chamber can be burned more efficiently.

(When each cylinder has three spark plugs)
As shown in FIG. 15, when each cylinder has three spark plugs, in the operation region “I” where stratified combustion is performed, the “multiple discharge pattern (that is, the discharge time extension) described in FIG. It is preferable to perform ignition by one spark plug while applying the “pattern” ”. Thereby, in the stratified combustion in which the distribution of the air-fuel mixture in the combustion chamber is likely to vary for each cycle of each cylinder, it is possible to lengthen the time interval at which ignition is possible. As a result, it is possible to increase the chance of ignition in stratified combustion and stabilize the combustion. In addition, in the “multiple discharge pattern” by one spark plug, the current is supplied in the cylinder having the spark plug (see FIG. 7 described above), in other words, the “multiple discharge pattern” does not straddle a plurality of cylinders. The “pattern” is preferably realized from the viewpoint of power saving.

  Further, in the operation region “II” in which the density of the air-fuel mixture in the combustion chamber is uniform during the EGR or the air lean burn, the “current enhancement pattern” described in FIG. 6 is applied, It is preferable to implement ignition with three spark plugs. This is because the combustion period is shortened by a plurality of ignitions. With this “current enhancement pattern”, larger flame nuclei can be grown in the combustion chamber to form stronger flame nuclei. Thereby, the air-fuel mixture in the combustion chamber can be burned more efficiently. In the “current enhancement pattern” using the three spark plugs, as described above with reference to FIG. 9, it is preferable to realize the “current enhancement pattern” across a plurality of cylinders from the viewpoint of increasing the discharge voltage.

  Further, in the operation region “III” that is close to the ideal air-fuel ratio and is a partial load, it is preferable to apply the “single discharge pattern” described in FIG. 6 and perform ignition with one spark plug. This is because in combustion at an ideal air-fuel ratio, sufficiently stable combustion can be ensured by discharging a relatively small current with one spark plug. This “single discharge pattern” eliminates the need to increase the amount of current required when the air-fuel mixture is ignited, thus realizing power savings and, in turn, improving the energy efficiency of the vehicle. .

  In addition, in the operation region “IV” that is a high load or a full load, it is preferable to apply the “current enhancement pattern” described in FIG. 6 and perform ignition with one spark plug. This is because the discharge voltage is lowered by ignition by one spark plug. In addition, since the airflow is stronger than in other operating areas, it is effective to effectively prevent the flame kernel from blowing off.

  In particular, since so-called multi-point ignition in which one cylinder ignites with a plurality of spark plugs has a short combustion period, the air-fuel mixture is ignited when the piston is positioned near the top dead center. At this time, since the pressure in the cylinder at the moment of ignition is remarkably high, the discharge voltage tends to increase remarkably by the inventor's research. Such a significant increase in the discharge voltage may cause physical damage to the coil and the spark plug in the ignition device, and may cause ignition failure due to current decay. For this reason, in a high-load operation state, it is possible to perform so-called one-point ignition in which one cylinder ignites with one ignition plug, and to change the ignition timing to an advance side compared with a reference value. preferable. The reference value in the ignition timing according to the present embodiment may typically mean an ignition timing at which the torque generated by the combustion of fuel becomes maximum. With this “current enhancement pattern”, larger flame nuclei can be grown in the combustion chamber to form stronger flame nuclei. Thereby, the air-fuel mixture in the combustion chamber can be burned more efficiently. In addition, in the “current enhancement pattern” using one spark plug, the current supply in the cylinder having the spark plug (see FIG. 7 described above), in other words, the “current enhancement pattern” does not cross a plurality of cylinders. The “pattern” is preferably realized from the viewpoint of power saving.

  Further, in the operation region “V” where the exhaust gas temperature is high and the degree of occurrence of knocking is high, the “single discharge pattern” described in FIG. 6 is applied and ignition by three spark plugs is performed. It is preferable to do. This is because the combustion period is shortened by a plurality of ignitions and the exhaust temperature is lowered. In addition, in this operating region, sufficiently stable combustion can be secured with a relatively small current. This “single discharge pattern” eliminates the need to increase the amount of current required when the air-fuel mixture is ignited, thus realizing power savings and, in turn, improving the energy efficiency of the vehicle. .

  Further, in the operation region (so-called cold operation region) “VI” where the engine temperature is lower than a predetermined temperature such as 40 ° C., for example, the “current enhancement pattern” described in FIG. 6 is applied. In both cases, it is preferable to perform ignition with three spark plugs. This is because in this operating region, only small flame nuclei can be formed, or the flame nuclei themselves are not generated, and the combustion state is unstable. Moreover, it is for shortening a combustion period by several ignition. With this “current enhancement pattern”, larger flame nuclei can be grown in the combustion chamber to form stronger flame nuclei. Thereby, the air-fuel mixture in the combustion chamber can be burned more efficiently. In the “current enhancement pattern” using the three spark plugs, as described above with reference to FIG. 9, it is preferable to realize the “current enhancement pattern” across a plurality of cylinders from the viewpoint of increasing the discharge voltage.

(Fifth embodiment)
(Switching the discharge state pattern according to the combustion state including misfire)
Next, the principle of switching the discharge state pattern according to the combustion state including misfire according to the fifth embodiment will be described with reference to FIGS. FIG. 16 is a graph showing temporal changes in the three types of combustion pressures for determining the combustion state including misfire according to the fifth embodiment. FIG. 17 is a graph showing time variation of carbon monoxide (HC) concentration or oxygen (O2) concentration for determining the combustion state including misfire according to the fifth embodiment (FIG. 17A). FIG. 17 is a graph (FIG. 17B) showing a change over time in carbon dioxide (CO 2) concentration for determining a combustion state including misfire.

  In 5th Embodiment, the pattern of a discharge state is switched according to three types of combustion states. The three kinds of combustion states typically include a complete combustion state, a semi-misfire state, and a complete misfire state. Complete combustion means a state of combustion in which the heat energy inherent in the air-fuel mixture is generated. The semi-misfire state means a state of combustion in which flame propagation stops and misfire occurs while combustion heat is generated, and a flame is not sufficiently formed. The complete misfire state means a state where the air-fuel mixture is misfired without being ignited and no combustion heat is generated.

  By switching the discharge state pattern according to such a combustion state, it is possible to effectively suppress the occurrence of torque fluctuations in the engine.

(Misfire detection by combustion pressure waveform)
Specifically, as shown in FIG. 16, the above-described three types of combustion states may be determined based on the waveform of the combustion pressure measured by the combustion pressure sensor. That is, it is determined whether it is a complete combustion state, a semi-misfire state, or a complete misfire state depending on which of the combustion pressure waveforms shown in FIG. Good.

(Judgment of misfire by the concentration of carbon monoxide)
Alternatively, as shown in FIG. 17A, the above-described three types of combustion states are obtained by comparing the carbon monoxide (HC) concentration measured by the concentration sensor, the misfire determination threshold value, and the complete combustion determination threshold value. You may judge. The determination of the combustion state is based on the fact that, when misfire occurs, (i) the emission of carbon monoxide (HC) tends to increase due to the generation of unburned fuel, and (ii) oxygen (O2 ) Is emitted without being combusted and oxygen (O2) emissions tend to increase, and (iii) carbon dioxide (CO2) emissions tend to decrease due to incomplete combustion Based on three trends.

  Specifically, as shown in FIG. 17A, when the carbon monoxide (HC) concentration measured by the concentration sensor exceeds a misfire determination threshold, the cylinder combustion chamber is completely misfired. You may judge. This misfire determination threshold is defined individually and specifically so as to be a value included in a predetermined range of the concentration of carbon monoxide (HC) in a complete misfire state by quantitatively or qualitatively analyzing the above three tendencies. You can do it.

  On the other hand, if the carbon monoxide (HC) concentration measured by the concentration sensor does not exceed the complete combustion determination threshold, it may be determined that the combustion chamber of the cylinder is in a complete combustion state. The complete combustion determination threshold is individually and specifically determined so that the above-mentioned three trends are quantitatively or qualitatively analyzed and become a value included in a predetermined range of the carbon monoxide (HC) concentration in the complete combustion state. May be defined.

  On the other hand, if the carbon monoxide (HC) concentration measured by the concentration sensor does not exceed the misfire determination threshold value and exceeds the complete combustion determination threshold value, it may be determined that the combustion chamber of the cylinder is in a semi-misfire state. . Note that the combustion state in the combustion chamber of the cylinder may be determined by a substantially similar determination process based on the oxygen (O2) concentration in addition to or instead of the carbon monoxide (HC) concentration.

(Judgment of misfire by the concentration of carbon dioxide)
Or, specifically, as shown in FIG. 17B, when the carbon dioxide (CO2) concentration measured by the concentration sensor exceeds the complete combustion determination threshold, the combustion chamber of the cylinder is in a complete combustion state. You may judge that it became. This complete combustion determination threshold is defined individually and specifically so as to be a value included in a predetermined range of carbon dioxide (CO2) concentration in the complete combustion state by quantitatively or qualitatively analyzing the above-mentioned three trends. You can do it.

  On the other hand, when the carbon dioxide (CO 2) concentration measured by the concentration sensor falls below the misfire determination threshold, it may be determined that the combustion chamber of the cylinder is in a complete misfire state. This misfire determination threshold is defined individually and specifically so as to be a value included in a predetermined range of carbon dioxide (CO2) concentration in a complete misfire state by quantitatively or qualitatively analyzing the above-mentioned three trends. It's okay.

  On the other hand, when the carbon dioxide (CO2) concentration measured by the concentration sensor falls below the complete combustion determination threshold and exceeds the misfire determination threshold, it may be determined that the combustion chamber of the cylinder has become a semi-misfire state.

(Failure detection using ion current)
Next, with reference to FIG. 18, the determination process for determining the above-described three types of combustion states based on the presence / absence of ion current generation and the comparison between the magnitude of torque fluctuation and a predetermined threshold will be described. FIG. 18 is a flowchart showing the flow of determination processing for determining the combustion state including misfire using the ionic current according to the fifth embodiment.

  As shown in FIG. 18, under the control of the ECU, the above-described determination process for determining the three types of combustion states is required (step S101).

  Next, the ion current is measured by the ion current sensor under the control of the ECU (step S102).

  Next, the ion current is measured under the control of the ECU, and it is determined whether or not the ion current is generated (step S103). Here, when it is determined that no ionic current is generated (step S103: No), it is determined that there is a complete misfire state because no ionic current is generated (step S104). On the other hand, when it is determined that an ionic current is generated as a result of the determination in step S103 (step S103: Yes), the magnitude of torque fluctuation is measured under the control of the ECU (step S105).

  Next, it is determined whether or not the measured magnitude of torque fluctuation exceeds a predetermined threshold value under the control of the ECU (step S106). Here, when it is determined that the magnitude of the measured torque fluctuation exceeds the predetermined threshold (step S106: Yes), the magnitude of the torque fluctuation exceeds the predetermined threshold and the ion current is detected. It determines with it being in a misfire state (step S107). On the other hand, as a result of the determination in step S106, when it is not determined that the measured magnitude of the torque fluctuation exceeds the predetermined threshold (step S106: No), it is determined that the combustion state is complete (step S108).

(Discharge state pattern switching control process according to the combustion state)
Next, with reference to FIGS. 19 to 21, a control process for switching the discharge state pattern according to the above-described three types of combustion states according to the fifth embodiment will be described.

(When each cylinder has one spark plug)
First, referring to FIG. 19, a control process for switching the discharge state pattern in accordance with the above-described three types of combustion states when each cylinder has one spark plug will be described. FIG. 19 is a flowchart showing the flow of the switching control process for switching the discharge state pattern in accordance with the combustion state including misfire when each cylinder according to the fifth embodiment has one spark plug. .

  As shown in FIG. 19, first, under the control of the ECU, the combustion state including misfire is determined by the various methods described above (step S201).

  Next, it is determined whether or not the vehicle is operating by stratified combustion under the control of the ECU (step S202). Here, when it is determined that the vehicle is not operated by stratified combustion (step S202: No), the “current enhancement pattern” described in FIG. 6 is applied to the ignition device (step S203).

  On the other hand, when it is determined as a result of the determination in step S202 that the vehicle is operating by stratified combustion (step S202: Yes), it is further determined whether or not the vehicle is in a complete misfire state under the control of the ECU. (Step S204). Here, when it is determined that the vehicle is in a complete misfire state (step S204: Yes), the “current enhancement pattern” described in FIG. 6 is applied to the ignition device (step S205). As a result, when a complete misfire occurs in the engine drive by stratified combustion or the engine drive by the combustion in which the air-fuel mixture is homogeneously distributed, a larger flame kernel grows in the combustion chamber and a more powerful flame. Nuclei can be formed. Thereby, the air-fuel mixture in the combustion chamber can be burned more efficiently.

  On the other hand, as a result of the determination in step S204 described above, if it is not determined that the vehicle is in a complete misfire state (step S204: No), the “multiple discharge pattern (ie, discharge time extension pattern)” described in FIG. Applied to the apparatus (step S206). Thereby, in the stratified combustion in which the distribution of the air-fuel mixture in the combustion chamber is likely to vary for each cycle of each cylinder, it is possible to lengthen the time interval at which ignition is possible. As a result, it is possible to increase the chance of ignition in stratified combustion and stabilize the combustion.

(When each cylinder has multiple spark plugs)
Next, with reference to FIG. 20 and FIG. 21, a control process for switching the discharge state pattern in accordance with the above-described three types of combustion states when each cylinder has a plurality of spark plugs will be described. FIG. 20 is a flowchart showing the flow of the switching control process for switching the discharge state pattern in accordance with the combustion state including misfire when each cylinder according to the fifth embodiment has a plurality of spark plugs. . FIG. 21 is a flowchart showing a subroutine of the flow of the switching control process for switching the discharge state pattern shown in FIG.

  As shown in FIG. 20, first, under the control of the ECU, the combustion state including misfire is determined by the various methods described above (step S301).

  Next, it is determined whether or not the vehicle is operating by stratified combustion under the control of the ECU (step S302). Here, when it is determined that the vehicle is not operated by stratified combustion (step S302: No), it is further determined whether or not the vehicle is in a complete misfire state under the control of the ECU (step S303). . When it is determined that the vehicle is in a complete misfire state (step S303: Yes), it is determined whether or not the “current enhancement pattern” described in FIG. 6 is already applied to the ignition device (step S304). ). Here, when it is not determined that the “current enhancement pattern” described in FIG. 6 has already been applied to the ignition device (step S304: No), the “current enhancement pattern” described in FIG. (Step S305). In the “current enhancement pattern” using a plurality of spark plugs, as described above with reference to FIG. 9, it is preferable that the “current enhancement pattern” is realized across a plurality of cylinders from the viewpoint of increasing the discharge voltage. With this “current enhancement pattern”, larger flame nuclei can be grown in the combustion chamber to form stronger flame nuclei. Thereby, the air-fuel mixture in the combustion chamber can be burned more efficiently.

  On the other hand, when it is determined as a result of the determination in step S304 that the “current enhancement pattern” described in FIG. 6 has already been applied to the ignition device (step S304: Yes), the EGR is controlled under the control of the ECU. It is determined whether it has been implemented (step S306). Here, when it is determined that EGR is being performed (step S306: Yes), the opening degree of the EGR valve is changed so that the EGR rate decreases under the control of the ECU (step S307). On the other hand, as a result of the determination in step S306, if it is not determined that EGR is being performed (step S306: No), the fuel injection amount is increased so that the air-fuel ratio becomes rich under the control of the ECU (step S306). S308). Thereby, combustion can be stabilized.

  On the other hand, as a result of the determination in step S303 described above, if it is not determined that the vehicle is in a complete misfire state (step S303: No), it is determined that the vehicle is in a semi-misfire state under the control of the ECU. Whether or not so-called multipoint ignition is performed is determined (step S309). Here, when it is determined that ignition by a plurality of spark plugs is performed in each cylinder (step S309: Yes), as described above, whether or not EGR is being performed under the control of the ECU. Determination is made (step S306).

  On the other hand, as a result of the determination in step S309, if it is not determined that ignition by a plurality of spark plugs is performed in each cylinder (step S309: No), each cylinder uses a plurality of spark plugs under the control of the ECU. The ignition device is driven so that ignition is performed (step S310).

(When the vehicle is driven by stratified combustion)
On the other hand, if it is determined that the vehicle is being operated by stratified combustion as a result of the determination in step S302 described above (step S302: Yes), whether or not the vehicle is completely misfired under the control of the ECU. Is determined (step S403). If it is determined that the vehicle is in a complete misfire state (step S403: Yes), it is determined whether or not the “current enhancement pattern” described in FIG. 6 is already applied to the ignition device (step S404). ). Here, when it is not determined that the “current enhancement pattern” described in FIG. 6 is already applied to the ignition device (step S404: No), the “current enhancement pattern” described in FIG. 6 is the ignition device. (Step S305). In the “current enhancement pattern” using a plurality of spark plugs, as described above with reference to FIG. 9, it is preferable that the “current enhancement pattern” is realized across a plurality of cylinders from the viewpoint of increasing the discharge voltage. With this “current enhancement pattern”, larger flame nuclei can be grown in the combustion chamber to form stronger flame nuclei. Thereby, the air-fuel mixture in the combustion chamber can be burned more efficiently.

  On the other hand, as a result of the determination in step S404, when it is determined that the “current enhancement pattern” described in FIG. 6 has already been applied to the ignition device (step S404: Yes), the EGR is controlled under the control of the ECU. It is determined whether it has been implemented (step S406). Here, when it is determined that the EGR is performed (step S406: Yes), the opening degree of the EGR valve is changed so that the EGR rate decreases under the control of the ECU (step S407). On the other hand, as a result of the determination in step S406, if it is not determined that EGR is being performed (step S406: No), the fuel injection amount is increased so that the air-fuel ratio becomes rich under the control of the ECU (step S406). S408). Thereby, the fuel can be burned more reliably and the combustion of the fuel can be stabilized.

  On the other hand, as a result of the determination in step S403 described above, when it is not determined that the vehicle is in a complete misfire state (step S403: No), it is determined that the vehicle is in a semi-misfire state under the control of the ECU. It is determined whether or not so-called multipoint ignition is performed (step S409). Here, when it is determined that ignition is performed by a plurality of spark plugs in each cylinder (step S409: Yes), the “current enhancement pattern” described above with reference to FIG. 6 under the control of the ECU. Is already applied to the ignition device (step S411). Here, if it is not determined that the “current enhancement pattern” described in FIG. 6 has already been applied to the ignition device (step S411: No), the “multiple discharge pattern (ie, discharge) described in FIG. (Time extension pattern) "is applied (step S412). Thereby, in the stratified combustion in which the distribution of the air-fuel mixture in the combustion chamber is likely to vary for each cycle of each cylinder, it is possible to lengthen the time interval at which ignition is possible. As a result, it is possible to increase the chance of ignition in stratified combustion and stabilize the combustion. In the “multiple discharge pattern” using a plurality of spark plugs, as described above with reference to FIG. 9, the realization of the “multiple discharge pattern” across a plurality of cylinders appropriately increases the discharge time. Is preferable. On the other hand, when it is determined that the “current enhancement pattern” described in FIG. 6 has already been applied to the ignition device as a result of the determination in step S411 (step S411: Yes), as described above, the control of the ECU Below, it is determined whether EGR is implemented (step S406).

  On the other hand, as a result of the determination in step S409, if it is not determined that ignition by a plurality of spark plugs is performed in each cylinder (step S409: No), each cylinder uses a plurality of spark plugs under the control of the ECU. The ignition device is driven so that ignition is performed (step S410).

  Thus, in the case of an engine in which each cylinder is ignited by a plurality of spark plugs, that is, a so-called multipoint ignition engine, when a semi-misfire caused by flame propagation failure occurs, It is preferable to prioritize switching. In the operation state of stratified combustion, it is preferable to try to extend the discharge period thereafter. And if it is a complete misfire state, since it is an ignition failure, it is preferable to synthesize | combine the discharge current from many cylinders, and to strengthen an electric current. Thereby, it is possible to effectively suppress the actually generated torque from fluctuating beyond the intended range, that is, so-called increase in torque fluctuation, depending on the combustion state.

(Sixth embodiment)
(Switching discharge pattern according to the occurrence of smoldering)
Next, with reference to FIGS. 22 and 23, the principle of switching the discharge state pattern in accordance with the occurrence of smoldering according to the sixth embodiment will be described. FIG. 22 is a flowchart showing the flow of the switching control process for switching the discharge state pattern according to the occurrence of smoldering according to the sixth embodiment. FIG. 23 is a block diagram schematically showing how the discharge state pattern is switched in the ignition device according to the sixth embodiment.

  As shown in FIG. 22, it is determined whether so-called smoldering is detected in the spark plug under the control of the ECU (step S501). Here, when smoldering is detected (step S501: Yes), a spark plug from which smoldering is detected is specified under the control of the ECU (step S502). On the other hand, when smoldering is not detected (step S501: No), the process returns to step S501 again.

  Next, the “current enhancement pattern” described with reference to FIG. 6 is applied to the identified spark plug (step S503). In the “current enhancement pattern” using a plurality of spark plugs, as described above with reference to FIG. 9, it is preferable that the “current enhancement pattern” is realized across a plurality of cylinders from the viewpoint of increasing the discharge voltage. With this “current enhancement pattern”, larger flame nuclei can be grown in the combustion chamber to form stronger flame nuclei. Thereby, the air-fuel mixture in the combustion chamber can be burned more efficiently.

  Specifically, as shown in FIG. 23, the plurality of coil portions 210a1, 210a2, 210a3, 210b1, 210b2, and the like in the plurality of cylinders 21a, 21b are operated by substantially the same operation as in the third embodiment described above. By simultaneously supplying the current generated in 210b3 to one spark plug 230a3, for example, the level of the discharge current can be increased to about 6 times the normal, and the mixture is ignited at a higher discharge voltage. Can do. As a result, it is possible to burn off the soot and deposit fuel, which are substances causing smoldering, with a high discharge voltage.

(Seventh embodiment)
(Switching the discharge state pattern according to the progress of wear)
Next, the principle of switching the discharge state pattern in accordance with the progress of the spark plug wear according to the seventh embodiment will be described with reference to FIGS. FIG. 24 is a flowchart showing the flow of the switching control process for switching the discharge state pattern according to the progress of the spark plug wear according to the seventh embodiment. FIG. 25 is a graph showing the correlation between the amount of wear and the number of discharges of the spark plug according to the seventh embodiment. FIG. 26 is a schematic diagram (FIG. 26 (a)) schematically showing discharge with a spark plug with little wear according to a general example, and schematically showing discharge with a spark plug with advanced wear according to a comparative example. FIG. 26B is a schematic diagram (FIG. 26B), and FIG. 26B is a schematic diagram schematically showing discharge in the spark plug in which wear has progressed according to the seventh embodiment.

  As shown in FIG. 24, under the control of the ECU, it is determined whether or not switching of the discharge state pattern is requested in accordance with the progress of the spark plug wear (step S601). Here, when it is determined that switching of the discharge state pattern is requested in accordance with the progress degree of the spark plug wear (step S601: Yes), the spark plug wear amount L is estimated under the control of the ECU. (Step S602). Specifically, as shown in FIG. 25, the inventor of the present application indicates that the amount of wear of the spark plug increases as the number of discharges of the spark plug increases, in other words, as the travel distance of the engine increases. It has been found by research. Thereby, the wear amount of the spark plug may be estimated indirectly by measuring the number of discharges of the spark plug and the travel distance of the engine. On the other hand, as a result of the determination in step S601 described above, when it is not determined that the switching of the discharge state pattern is requested according to the progress of the spark plug wear (step S601: No), the process returns to step S601 again.

  Next, it is determined whether or not the estimated wear amount L exceeds the wear amount threshold value L_s under the control of the ECU (step S603). Here, the wear amount threshold value L_s according to the present embodiment may typically mean a wear amount at which the probability of occurrence of discharge blowout exceeds a predetermined level. As a result of the determination in step S603, when it is determined that the estimated wear amount L exceeds the wear amount threshold value L_s (step S603: Yes), the current engine rotation speed Ne exceeds the rotation speed threshold value Ne_s. Further, it is determined whether or not the current engine load factor has exceeded a load factor threshold value (step S604). Here, the rotation speed threshold value Ne_s according to the present embodiment may typically mean a rotation speed at which the probability of occurrence of discharge blowout exceeds a predetermined level. Further, the load factor KL according to the present embodiment is typically the ratio of the intake amount actually sucked into the engine with respect to a certain amount, or the load factor KL according to the present embodiment is typical. May mean the ratio of the fuel injection quantity actually injected into the engine to a certain quantity. Further, the load factor threshold KL_s according to the present embodiment may typically mean a load factor at which the probability of occurrence of discharge discharge exceeds a predetermined level. Here, when it is determined that the current engine rotational speed Ne exceeds the rotational speed threshold value Ne_s and the current engine load factor KL exceeds the load factor threshold value KL_s (step S604: Yes), this wear. The “current enhancement pattern” described with reference to FIG. 6 is applied to the spark plug that has progressed (step S503). In the “current enhancement pattern” using a plurality of spark plugs, as described above with reference to FIG. 9, it is preferable that the “current enhancement pattern” is realized across a plurality of cylinders from the viewpoint of increasing the discharge voltage. With this “current enhancement pattern”, for example, even when the airflow speed is significantly high due to the high rotation and high load operating conditions, larger flame nuclei are grown in the combustion chamber to form stronger flame nuclei. be able to. As a result, the occurrence of blow-off of the discharge can be eliminated almost or completely, and the air-fuel mixture in the combustion chamber can be burned more reliably and efficiently.

  Specifically, as shown in FIG. 26 (a), in a spark plug with little wear, generally, although the discharge is stretched by the airflow, the discharge does not blow out. On the other hand, as shown in FIG. 26B, in the spark plug in which the wear has progressed, the plug gap is expanded due to the wear, and the discharge voltage is extremely increased. For this reason, as the discharge voltage increases, the amount of current decreases, the discharge is stretched by the air flow, and the discharge blows out.

  On the other hand, according to the seventh embodiment, as shown in FIG. 26C, the “current enhancement pattern” described in FIG. 6 is applied to the spark plug in which the wear has progressed. Therefore, for example, even when the air velocity is remarkably large due to the high rotation and high load operation state, larger flame nuclei can be grown in the combustion chamber to form stronger flame nuclei. As a result, the occurrence of blow-off of the discharge can be eliminated almost or completely, and the air-fuel mixture in the combustion chamber can be burned more reliably and efficiently.

  The present invention is not limited to the above-described embodiment, and can be appropriately changed without departing from the spirit or idea of the invention that can be read from the claims and the entire specification. Ignition of an internal combustion engine accompanying such a change The control device is also included in the technical scope of the present invention.

  The ignition control device for an internal combustion engine according to the present invention can be used for an ignition control device for an internal combustion engine using a spark plug and an ignition coil, for example.

DESCRIPTION OF SYMBOLS 10 ... Ignition control apparatus, 100 ... ECU, 200 ... Ignition apparatus 200, 210a, 210b, 210c, 210d ... Coil part, 220a, 220b, 220c, 220d ... Switch element, 230a, 230b, 230c, 230d ... Spark plug, SWA , SWB, SWC, switch signal, IG, ignition signal, 300, engine, exhaust sensor 317, and cylinder pressure sensor 332.

Claims (19)

An ignition control device for a spark plug provided in a cylinder of an internal combustion engine,
A first coil capable of generating a first current that is a secondary current;
A second coil capable of generating a second current that is a secondary current;
A first spark plug that can be discharged by being supplied with the secondary current;
A second spark plug capable of discharging when supplied with the secondary current;
The generated first current can be supplied to any one of the first spark plug and the second spark plug, and the generated second current can be supplied to any one of the ignition plugs. A switch element that can be supplied to the plug;
Control means for controlling the switch element so as to supply the first current and the second current to either one of the spark plugs at a predetermined timing according to an operating state of the internal combustion engine, respectively. An internal combustion engine ignition control device.   The said control means controls the said switch element so that the said 1st electric current and the said 2nd electric current may be simultaneously supplied to one of the said ignition plugs as the said predetermined timing. An ignition control device for an internal combustion engine.   The control means controls the switch element to supply the first current and the second current to the one of the spark plugs at different timings as the predetermined timing, respectively. Or the ignition control apparatus of the internal combustion engine of 2.   When the operation state is an operation state of stratified combustion or a cold operation state, the control means causes the first current and the second current to the one of the spark plugs to increase the discharge time. The ignition control device for an internal combustion engine according to any one of claims 1 to 3, wherein the switch elements are controlled so as to be supplied respectively.   When the operation state is a lean combustion operation state, the control means supplies the first current and the second current to either one of the spark plugs simultaneously as the predetermined timing. The ignition control device for an internal combustion engine according to any one of claims 1 to 4, wherein the ignition control device is controlled.   When the operation state is a high load or full load operation state, the control means supplies the first current and the second current to either one of the spark plugs simultaneously as the predetermined timing. The ignition control device for an internal combustion engine according to any one of claims 1 to 5, wherein the switch element is controlled.   The control means controls the switch element so as to supply the first current and the second current to the any one of the spark plugs so that a discharge timing in the any one of the spark plugs is advanced. The ignition control device for an internal combustion engine according to claim 6.   The control means supplies the first current to the first spark plug as the predetermined timing when the operating state is a warm partial load operating state or an operating state under an ideal air-fuel ratio condition. The ignition control device for an internal combustion engine according to any one of claims 1 to 7, wherein the switch element is controlled so as to supply the second current to the second spark plug.   When the operation state is not the stratified combustion operation state or the cold operation state, the control means supplies the first current and the second current simultaneously to any one of the spark plugs as the predetermined timing. The ignition control device for an internal combustion engine according to any one of claims 1 to 8, wherein the switch element is controlled. An ignition control device for a spark plug provided in a cylinder of an internal combustion engine,
A first coil capable of generating a first current that is a secondary current;
A second coil capable of generating a second current that is a secondary current;
A first spark plug that can be discharged by being supplied with the secondary current;
A second spark plug capable of discharging when supplied with the secondary current;
The generated first current can be supplied to any one of the first spark plug and the second spark plug, and the generated second current can be supplied to any one of the ignition plugs. A switch element that can be supplied to the plug;
A specifying means for specifying a combustion state in the cylinder;
Control means for controlling the switch element so as to supply the first current and the second current to either one of the spark plugs at a predetermined timing according to the specified combustion state, respectively. An internal combustion engine ignition control device. The specifying means includes misfire specifying means for specifying a misfire state in the cylinder,
The control means controls the switch element to supply the first current and the second current to the any one of the spark plugs at the predetermined timing according to the specified misfire state. The ignition control device for an internal combustion engine according to claim 10.   When the specified misfire state is a complete misfire state, the control means supplies the first current and the second current to either one of the spark plugs simultaneously as the predetermined timing. When the specified misfire state is a semi-misfire state, the first current is supplied to the first spark plug, and the second current is provided in the same cylinder as the first spark plug. The ignition control device for an internal combustion engine according to claim 11, wherein the switch element is controlled so as to be supplied to the second spark plug.   The misfire specifying means specifies the misfire state based on quantitative or qualitative information on at least one of a combustion pressure waveform in the cylinder, an exhaust gas component, and an ion current. The ignition control device for an internal combustion engine according to claim 11 or 12. The specifying means includes smolder specifying means that makes it impossible to specify a smoldering state of a spark plug in the cylinder,
The control means controls the switch element to supply the first current and the second current to the any one of the spark plugs at the predetermined timing according to the specified smoldering state. The ignition control device for an internal combustion engine according to any one of claims 10 to 13, wherein the ignition control device is an internal combustion engine.   When the smoldering state is specified, the control means controls the switch element to supply the first current and the second current to either one of the spark plugs as the predetermined timing. 15. The ignition control device for an internal combustion engine according to claim 14, wherein the ignition control device is an internal combustion engine. The specifying means includes a wear state specifying means capable of specifying a wear state of the spark plug in the cylinder,
The control means controls the switch element so as to supply the first current and the second current to the any one of the spark plugs at the predetermined timing according to the specified wear state. 16. The ignition control device for an internal combustion engine according to claim 10, wherein the ignition control device is an internal combustion engine.   The control means controls the switch element so as to supply the first current and the second current to either one of the spark plugs simultaneously as the predetermined timing when the wear state is specified. The ignition control device for an internal combustion engine according to claim 16, wherein the ignition control device is an internal combustion engine. The internal combustion engine has a plurality of cylinders,
The first spark plug is provided in a first cylinder of the plurality of cylinders,
The ignition control device for an internal combustion engine according to any one of claims 1 to 17, wherein the second spark plug is provided in a second cylinder of the plurality of cylinders.   The internal combustion engine ignition control device according to any one of claims 1 to 17, wherein the first spark plug and the second spark plug are provided in the same cylinder.