JP2014227960A - Ignition control device - Google Patents

Abstract

A configuration capable of satisfactorily stabilizing a combustion state of a fuel mixture while suppressing an increase in physique and manufacturing cost as much as possible.
A control unit (319) releases stored energy from a capacitor (317) during ignition discharge (started by turning off the first switching element (313)) (of the third switching element (315)). In order to supply the primary current to the other end side opposite to the one end connected to the DC power source (312) of the primary winding (311a), by turning off and turning on the second switching element (314). Each switching element is controlled. In particular, in the present invention, the control unit variably sets the duty ratio in the second control signal input to the second control terminal (314G) of the second switching element.
[Selection] Figure 2

Description

  The present invention relates to an ignition control device configured to control the operation of a spark plug provided to ignite a fuel mixture in a cylinder of an internal combustion engine.

  Various devices of this type having a structure for stabilizing the combustion state of the fuel mixture have been proposed. For example, Japanese Patent Application Laid-Open No. 2007-231927 discloses a configuration in which a plurality of discharges are intermittently generated within one combustion stroke. Japanese Patent Laid-Open No. 2000-199470 discloses a configuration in which two ignition coils are connected in parallel to obtain multiple discharge characteristics with a long discharge time. Furthermore, in Japanese Patent Application Laid-Open No. 11-159427, in addition to the voltage generated in the secondary coil in the ignition coil, a DC / DC converter connected to the low voltage side of the secondary coil is used. A configuration capable of applying a generated auxiliary voltage is disclosed.

JP-A-11-159427 JP 2000-199470 A JP 2007-231927 A

  When a plurality of discharges are intermittently generated in one combustion stroke as in the configuration described in Japanese Patent Laid-Open No. 2007-231927, during the period from the start to the end of the ignition discharge in the stroke, The ignition discharge current repeatedly becomes zero. Then, particularly when the gas flow rate in the cylinder is large, there may be a problem that ignition energy is lost due to so-called “blown out”.

  On the other hand, as described in Japanese Patent Application Laid-Open No. 2000-199470, in the configuration in which two ignition coils are connected in parallel, the ignition discharge current is repeatedly generated from the start to the end of the ignition discharge within one combustion stroke. Although it does not become zero, there is a problem that the device configuration is complicated and the physique (device size) is also increased. In addition, in the related art, there is a problem that wasteful power consumption occurs due to the configuration (physique) that greatly exceeds the energy required for ignition.

  Further, as described in JP-A-11-159427, in a configuration in which an auxiliary voltage is applied to the secondary side of the ignition coil, a high breakdown voltage is required for a circuit for applying the auxiliary voltage. The For this reason, even in such a configuration, there are problems in the physique and cost.

  The present invention has been made in view of the circumstances exemplified above. That is, an object of the present invention is to provide a configuration capable of satisfactorily stabilizing the combustion state of a fuel mixture while suppressing an increase in physique and manufacturing cost as much as possible.

  The ignition control device (30) of the present invention is configured to control the operation of the spark plug (19). Here, the spark plug is provided so as to ignite the fuel mixture in the cylinder (11b) of the internal combustion engine (11). The ignition control device of the present invention includes an ignition coil (311), a DC power supply (312), a first switching element (313), a second switching element (314), a third switching element (315), an energy A storage coil (316), a capacitor (317), and a control unit (319) are provided.

  The ignition coil includes a primary winding (311a) and a secondary winding (311b). The secondary winding is connected to the spark plug. The ignition coil is configured such that a secondary current is generated in the secondary winding by increasing or decreasing a primary current (current flowing through the primary winding). In addition, an ungrounded output terminal of the DC power supply is connected to one end of the primary winding so that the primary current flows through the primary winding.

  The first switching element has a first control terminal (313G), a first power supply side terminal (313C), and a first ground side terminal (313E). The first switching element is a semiconductor switching element, and based on a first control signal input to the first control terminal, an energization between the first power supply side terminal and the first ground side terminal is performed. It is configured to control on / off. In the first switching element, the first power supply side terminal is connected to the other end side of the primary winding. The first ground side terminal is connected to the ground side.

  The second switching element has a second control terminal (314G), a second power supply side terminal (314D), and a second ground side terminal (314S). The second switching element is a semiconductor switching element, and based on a second control signal input to the second control terminal, an energization between the second power supply side terminal and the second ground side terminal is performed. It is configured to control on / off. In the second switching element, the second ground side terminal is connected to the other end side of the primary winding.

  The third switching element has a third control terminal (315G), a third power supply side terminal (315C), and a third ground side terminal (315E). The third switching element is a semiconductor switching element, and based on a third control signal input to the third control terminal, an energization between the third power supply side terminal and the third ground side terminal is performed. It is configured to control on / off. In the third switching element, the third power supply side terminal is connected to the second power supply side terminal in the second switching element. The third ground side terminal is connected to the ground side.

  The energy storage coil is an inductor interposed in a power line that connects the non-grounded output terminal of the DC power supply and the third power supply side terminal of the third switching element. The energy storage coil is provided so as to store energy when the third switching element is turned on and to release the stored energy when the third switching element is turned off.

  The capacitor is connected in series with the energy storage coil between the non-grounded output terminal of the DC power source and the grounded side. The capacitor is provided so as to store energy released from the energy storage coil when the third switching element is turned off.

  The control unit is provided to control the second switching element and the third switching element. Specifically, the control unit turns off the third switching element and turns on the second switching element during ignition discharge of the spark plug (which is started by turning off the first switching element). It is like that. That is, the control unit releases the stored energy from the capacitor by operating the second switching element and the third switching element as described above, and transmits the released energy to the primary winding. Thus, the switching elements are controlled so as to be supplied from the other end side to the primary winding as energy for passing the primary current. Particularly, in the present invention, the control unit variably sets the duty ratio in the second control signal.

  First, a typical operation of the ignition control device of the present invention having such a configuration will be described. When the first switching element is turned on and the second switching element is turned off, the primary current flows through the primary winding. To do. Thereby, the ignition coil is charged. On the other hand, energy is stored in the energy storage coil by turning on the third switching element during this time. Further, this stored energy is released from the energy storage coil and stored in the capacitor when the third switching element is turned off.

  When the first switching element is turned off in a state where the second switching element and the third switching element are turned off, the primary current that has been flowing through the primary winding until then is rapidly cut off. . Then, a high voltage is generated in the primary winding of the ignition coil, and the high voltage is further boosted in the secondary winding, so that a high voltage is generated in the spark plug and a discharge is generated. At this time, a large secondary current is generated in the secondary winding. Thereby, the ignition discharge is started by the spark plug.

  By the way, after the ignition discharge is started by the spark plug, the secondary current (hereinafter sometimes referred to as “discharge current”) approaches zero as time passes. In this regard, in the configuration of the present invention, during the ignition discharge, the third switching element is turned off and the second switching element is turned on (the second switching element is turned on while the third switching element is turned off). Thus, stored energy is released from the capacitor.

  Then, the energy released from the capacitor is supplied to the primary winding from the other end side so that the primary current flows through the primary winding. As a result, the discharge current is ensured satisfactorily to such an extent that the ignition discharge can be maintained. Here, the flow state of the discharge current during the ignition discharge can be appropriately controlled by adjusting the amount of stored energy released from the capacitor by turning on and off the second switching element.

  Therefore, in the ignition control device of the present invention, the control unit variably sets the duty ratio (that is, the on-duty of the second switching element) in the second control signal. For example, the control unit sets the duty ratio according to an operating state of the internal combustion engine so as to maintain the secondary current (the discharge current) at a predetermined value or more. Specifically, for example, the control unit increases the duty ratio over time. In this case, the control unit may variably set the increasing rate of the duty ratio with time.

  According to the ignition control device of the present invention having such a configuration, the flow state of the discharge current is good corresponding to the gas flow state in the cylinder so as not to cause so-called “blown out”. It becomes possible to control to. Therefore, according to the present invention, the occurrence of so-called “blown out” and the resulting loss of ignition energy are satisfactorily suppressed by a simple device configuration. That is, according to the present invention, it is possible to satisfactorily stabilize the combustion state of the fuel mixture while suppressing as much as possible the increase in physique and manufacturing cost in the ignition control device.

  In particular, in the present invention, as described above, energy is input from the low voltage side (the ground side or the first switching element side) of the primary winding. For this reason, it is possible to input energy at a lower pressure than when energy is input from the secondary winding side.

  In this regard, if energy is input at a voltage higher than the voltage of the DC power supply from the high-voltage side (the DC power supply side, that is, the one end side) of the primary winding, the efficiency is deteriorated due to an inflow current to the DC power supply. Become. On the other hand, according to the present invention, as described above, since energy is input from the low-voltage side of the primary winding, an excellent effect that energy can be input to the primary winding most easily and efficiently. Is played.

1 is a schematic configuration diagram of an engine system having the configuration of an embodiment of the present invention. FIG. 2 is a schematic circuit diagram of the ignition control device shown in FIG. 1. The map for operation | movement description of the ignition control apparatus shown by FIG. The time chart for operation | movement description of the ignition control apparatus shown by FIG. The time chart for operation | movement description of the ignition control apparatus shown by FIG.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, an embodiment of the invention will be described with reference to the drawings. In addition, since a modification will prevent understanding of description of one consistent embodiment, if it is inserted during the description of the said embodiment, it is described collectively at the end.

<Engine system configuration>
Referring to FIG. 1, an engine system 10 includes an engine 11 that is a spark ignition type internal combustion engine. A cylinder 11b and a water jacket 11c are formed inside an engine block 11a constituting the main body of the engine 11. The cylinder 11b is provided so as to accommodate the piston 12 so as to be capable of reciprocating. The water jacket 11c is a space through which a cooling liquid (also referred to as cooling water) can flow, and is provided so as to surround the cylinder 11b.

  An intake port 13 and an exhaust port 14 are formed in the cylinder head at the top of the engine block 11a so as to be able to communicate with the cylinder 11b. In addition, an intake valve 15, an exhaust valve 16, and a valve drive mechanism 17 are attached to the cylinder head. The intake valve 15 is provided so that the communication state between the intake port 13 and the cylinder 11b can be changed. The exhaust valve 16 is provided so that the communication state between the exhaust port 14 and the cylinder 11b can be changed. The valve drive mechanism 17 is configured to open and close the intake valve 15 and the exhaust valve 16 at a predetermined timing.

  Further, an injector 18 and a spark plug 19 are attached to the engine block 11a. In the present embodiment, the injector 18 is provided so as to inject fuel directly into the cylinder 11b. The spark plug 19 is provided to ignite the fuel mixture in the cylinder 11b.

  A supply / exhaust mechanism 20 is connected to the engine 11. The supply / exhaust mechanism 20 is provided with three types of gas passages: an intake pipe 21 (including an intake manifold 21a and a surge tank 21b), an exhaust pipe 22, and an EGR passage 23 (EGR is an abbreviation for Exhaust Gas Recirculation). It has been.

  The intake manifold 21 a is connected to the intake port 13. The surge tank 21b is disposed upstream of the intake manifold 21a in the intake air flow direction. The exhaust pipe 22 is connected to the exhaust port 14.

  The EGR passage 23 is provided so that a part of the exhaust gas discharged to the exhaust pipe 22 can be introduced into the intake air by connecting the exhaust pipe 22 and the surge tank 21b. An EGR control valve 24 is interposed in the EGR passage 23. The EGR control valve 24 is provided so as to be able to control the EGR rate (the mixing ratio of exhaust gas in the pre-combustion gas sucked into the cylinder 11b) by the opening degree.

  A throttle valve 25 is interposed in the intake pipe 21 upstream of the surge tank 21b in the intake air flow direction. The opening degree of the throttle valve 25 is controlled by the operation of a throttle actuator 26 such as a DC motor. Further, an air flow control valve 27 for generating a swirl flow or a tumble flow is provided in the vicinity of the intake port 13.

  The engine system 10 is provided with an ignition control device 30. The ignition control device 30 is configured to control the operation of the spark plug 19 (that is, to perform ignition control in the engine 11). The ignition control device 30 includes an ignition circuit unit 31 and an electronic control unit 32.

  The ignition circuit unit 31 is configured to cause the spark plug 19 to generate spark discharge for igniting the fuel mixture in the cylinder 11b. The electronic control unit 32 is a so-called engine ECU (ECU is an abbreviation for Electronic Control Unit). The electronic control unit 32 controls the injector 18 and the ignition circuit unit 31 in accordance with the operating state of the engine 11 (hereinafter referred to as “engine parameter”) acquired based on the outputs of various sensors such as the rotational speed sensor 33. It controls the operation of each part including it.

  Regarding the ignition control, the electronic control unit 32 generates and outputs an ignition signal IGt and an energy input period signal IGw based on the acquired engine parameters. The ignition signal IGt and the energy input period signal IGw are the optimum ignition timing and discharge current according to the state of the gas in the cylinder 11b and the required output of the engine 11 (which changes according to the engine parameters). (Ignition discharge current) is defined. Since these signals are already known or well known, further detailed description of these signals will be omitted in this specification (Japanese Patent Laid-Open No. 2002-168170 (US Pat. No. 6,557,537) etc. However, in these known or well-known technical documents, IGw is referred to as “multiple period signal” or “discharge section signal”.

  The rotational speed sensor 33 is a sensor for detecting (acquiring) an engine rotational speed (also referred to as an engine rotational speed) Ne. The rotational speed sensor 33 is mounted on the engine block 11a so as to generate a pulse-like output corresponding to the rotational angle of a crankshaft (not shown) that rotates with the reciprocating motion of the piston 12. The cooling water temperature sensor 34 is a sensor for detecting (acquiring) the cooling water temperature Tw, which is the temperature of the coolant flowing through the water jacket 11c, and is attached to the engine block 11a.

  The air flow meter 35 is a sensor for detecting (acquiring) the intake air amount Ga (the mass flow rate of the intake air introduced into the cylinder 11b through the intake pipe 21). The air flow meter 35 is attached to the intake pipe 21 upstream of the throttle valve 25 in the intake air flow direction. The intake pressure sensor 36 is a sensor for detecting (acquiring) intake pressure Pa, which is the pressure in the intake pipe 21, and is attached to the surge tank 21b.

  The throttle opening sensor 37 is a sensor that generates an output corresponding to the opening of the throttle valve 25 (throttle opening THA), and is built in the throttle actuator 26. The accelerator position sensor 38 is provided so as to generate an output corresponding to an accelerator operation amount (accelerator operation amount ACCP) (not shown).

<Configuration of ignition control device>
Referring to FIG. 2, the ignition circuit unit 31 includes an ignition coil 311 (including a primary winding 311a and a secondary winding 311b), a DC power supply 312, a first switching element 313, a second switching element 314, A third switching element 315, an energy storage coil 316, a capacitor 317, diodes 318a, 318b and 318c, and a driver circuit 319 are provided.

  As described above, the ignition coil 311 includes the primary winding 311a and the secondary winding 311b. As is well known, the ignition coil 311 is configured to generate a secondary current in the secondary winding 311b by increasing or decreasing the primary current flowing through the primary winding 311a.

  A non-grounded output terminal (specifically, a + terminal) of the DC power supply 312 is connected to a high voltage side terminal (which may also be referred to as a non-grounded side terminal) which is one end of the primary winding 311a. On the other hand, the low voltage side terminal (which may also be referred to as a ground side terminal) side which is the other end of the primary winding 311 a is connected to the ground side via the first switching element 313. That is, the DC power supply 312 is provided so that when the first switching element 313 is turned on, a primary current flows in the direction from the high-voltage side terminal side to the low-voltage side terminal side in the primary winding 311a. ing.

  The high voltage side terminal (which may also be referred to as a non-ground side terminal) side in the secondary winding 311b is connected to the high voltage side terminal side in the primary winding 311a via a diode 318a. The anode of the diode 318a is connected to the high voltage side terminal side of the secondary winding 311b. That is, the diode 318a inhibits the passage of a current in the direction from the high voltage side terminal side of the primary winding 311a to the high voltage side terminal side of the secondary winding 311b, while passing the secondary current (discharge current). It is provided so as to be defined in a direction from the spark plug 19 toward the secondary winding 311b (that is, the current I2 in the figure becomes a negative value). On the other hand, the low voltage side terminal (which may also be referred to as a ground side terminal) side of the secondary winding 311 b is connected to the spark plug 19.

  The first switching element 313 is an IGBT (IGBT is an abbreviation of Insulated Gate Bipolar Transistor) which is a MOS gate structure transistor, and includes a first control terminal 313G, a first power supply side terminal 313C, and a first ground side terminal 313E. ,have. The first switching element 313 controls on / off of energization between the first power supply side terminal 313C and the first ground side terminal 313E based on the first control signal IGa input to the first control terminal 313G. It is configured. In the present embodiment, the first power supply side terminal 313C is connected to the low voltage side terminal side of the primary winding 311a. The first ground side terminal 313E is connected to the ground side.

  The second switching element 314 is a MOSFET (MOSFET is an abbreviation for Metal Oxide Semiconductor Field Effect Transistor), and has a second control terminal 314G, a second power supply side terminal 314D, and a second ground side terminal 314S. ing. The second switching element 314 controls on / off of energization between the second power supply side terminal 314D and the second ground side terminal 314S based on the second control signal IGb input to the second control terminal 314G. It is configured.

  In the present embodiment, the second ground side terminal 314S is connected to the low voltage side terminal side of the primary winding 311a via the diode 318b. The anode of the diode 318b is connected to the second ground side terminal 314S. That is, the diode 318b is provided to allow current to flow in the direction from the second ground side terminal 314S of the second switching element 314 toward the low voltage side terminal side of the primary winding 311a.

  The third switching element 315 is an IGBT that is a MOS gate structure transistor, and includes a third control terminal 315G, a third power supply side terminal 315C, and a third ground side terminal 315E. The third switching element 315 controls on / off of energization between the third power supply side terminal 315C and the third ground side terminal 315E based on the third control signal IGc input to the third control terminal 315G. It is configured.

  In the present embodiment, the third power supply side terminal 315C is connected to the second power supply side terminal 314D in the second switching element 314 via the diode 318c. The anode of the diode 318c is connected to the third power supply side terminal 315C. That is, the diode 318c is provided to allow current to flow in a direction from the third power supply side terminal 315C of the third switching element 315 toward the second power supply side terminal 314D of the second switching element 314. The third ground side terminal 315E of the third switching element 315 is connected to the ground side.

  The energy storage coil 316 is an inductor interposed in a power line that connects the above-described non-grounded output terminal in the DC power supply 312 and the third power supply terminal 315C in the third switching element 315. The energy storage coil 316 is provided to store energy (electromagnetic energy) when the third switching element 315 is turned on and to release the stored energy when the third switching element 315 is turned off.

  The capacitor 317 is connected in series with the energy storage coil 316 between the ground side and the above-described non-ground side output terminal of the DC power supply 312. That is, the capacitor 317 is connected in parallel with the third switching element 315 with respect to the energy storage coil 316. The capacitor 317 is provided so as to store energy released from the energy storage coil 316 when the third switching element 315 is turned off.

  The driver circuit 319 constituting the “control unit” of the present invention is connected to the electronic control unit 32 so as to receive the engine parameter, the ignition signal IGt, and the energy input period signal IGw output from the electronic control unit 32. . The driver circuit 319 is connected to the first control terminal 313G, the second control terminal 314G, and the third control terminal 315G so as to control the first switching element 313, the second switching element 314, and the third switching element 315. Has been. The driver circuit 319 generates a first control signal IGa, a second control signal IGb, and a third control signal IGc based on the received ignition signal IGt and energy input period signal IGw, respectively, as a first control terminal 313G and a second control signal IGc. It is provided to output to the control terminal 314G and the third control terminal 315G.

  Specifically, the driver circuit 319 turns off the third switching element 315 and turns on the second switching element 314 during ignition discharge of the spark plug 19 (this is started by turning off the first switching element 313). As a result, the stored energy is discharged from the capacitor 317. That is, the driver circuit 319 controls each switching element as described above to release energy (electrostatic energy) from the capacitor 317 and to pass the primary current through the primary winding 311a. Energy (hereinafter referred to as “input energy”) is supplied to the primary winding 311a from the low-voltage side terminal side.

  In particular, in the present embodiment, the driver circuit 319 is configured to variably set the duty ratio in the third control signal IGc according to the engine parameter. That is, the driver circuit 319 variably controls the amount of energy (electrostatic energy) accumulated in the capacitor 317 by setting the on-duty of the third switching element 315 according to the engine parameter.

  In the present embodiment, the driver circuit 319 variably sets the duty ratio in the second control signal IGb according to the engine parameter. That is, the driver circuit 319 variably controls the amount of energy supplied from the capacitor 317 to the low voltage side terminal side in the primary winding 311a by setting the on-duty of the second switching element 314 according to the engine parameter. ing.

  Specifically, in the present embodiment, the driver circuit 319 sets the duty ratio in the second control signal IGb so as to keep the discharge current at a predetermined value or higher so as not to blow out due to the increase in the flow velocity in the cylinder 11b. It increases with time in one combustion cycle. Further, the driver circuit 319 uses the map (look-up table) shown in FIG. 3, so that the driver circuit 319 accompanies the passage of time during one combustion cycle according to the intake pressure Pa and the engine speed Ne that are engine parameters. The duty ratio increase rate ΔDUTY is variably set.

<Description of operation>
The operation (action / effect) according to the configuration of the present embodiment will be described below. 4 and 5, “Vdc” indicates the voltage of the capacitor 317, “I1” indicates the primary current, and “I2” indicates the secondary current.

  In the figure, in the time chart of the primary current “I1” and the secondary current “I2”, it is assumed that the direction indicated by the arrow in FIG. 2 is a positive value. Further, the ignition signal IGt, the energy input period signal IGw, the first control signal IGa, the second control signal IGb, and the third control signal IGc are “H” in the state of rising upward in the drawing and falling downward. It is assumed that the status is “L”.

  The electronic control unit 32 controls the operation of each part in the engine system 10 including the injector 18 and the ignition circuit unit 31 according to the engine parameter acquired based on the output of various sensors such as the rotation speed sensor 33. Here, the ignition control will be described in detail. The electronic control unit 32 generates an ignition signal IGt and an energy input period signal IGw based on the acquired engine parameter. Then, the electronic control unit 32 outputs the generated ignition signal IGt, energy input period signal IGw, and engine parameters to the driver circuit 319.

  When the driver circuit 319 receives the ignition signal IGt, the energy input period signal IGw, and the engine parameter output from the electronic control unit 32, the first control signal for controlling on / off of the first switching element 313 based on these signals. The second control signal IGb for controlling on / off of the second switching element 314 and the third control signal IGc for controlling on / off of the third switching element 315 are output.

  In the present embodiment, the first control signal IGa is the same as the ignition signal IGt. For this reason, the driver circuit 319 outputs the received ignition signal IGt as it is toward the first control terminal 313G in the first switching element 313.

  On the other hand, the second control signal IGb is generated based on the received engine parameter and energy input period signal IGw and the map shown in FIG. Therefore, the driver circuit 319 generates the second control signal IGb based on the received engine parameter and the energy input period signal IGw and the map shown in FIG. 3, and the second control signal IGb Is output toward the second control terminal 314G of the second switching element 314.

  Here, as shown in FIG. 4, in the present embodiment, the second control signal IGb is a rectangular wave pulse having a constant cycle that is repeatedly output while the energy input period signal IGw is at the H level. Signal. In the second control signal IGb, the duty ratio is set based on the engine parameters (specifically, the intake pressure Pa and the engine speed Ne) and the map of FIG. 3 as time elapses between the times t3 and t4. It is generated so as to increase at an increase rate ΔDUTY.

  The third control signal IGc is generated based on the received ignition signal IGt and engine parameters. Therefore, the driver circuit 319 generates the third control signal IGc based on the received ignition signal IGt and the engine parameter, and directs the third control signal IGc toward the third control terminal 315G in the third switching element 315. Output. In the present embodiment, the third control signal IGc is a rectangular-wave pulse signal having a constant cycle that is repeatedly output while the ignition signal IGt is at the H level. The duty ratio of the third control signal IGc is constant between times t1 and t2, and is set based on engine parameters.

  Hereinafter, the operation according to the configuration of the present embodiment will be described in detail in time series with reference to FIG. First, the electronic control unit 32 acquires engine parameters such as the accelerator operation amount ACCP at a predetermined crank angle in a certain cylinder 11b. Then, the electronic control unit 32 determines the ignition timing in the current combustion stroke of the cylinder 11b based on the acquired engine parameter before the time t1 in FIG. Thereby, the ignition signal IGt and the energy input period signal IGw in the current combustion stroke are generated.

  When ignition signal IGt rises to H level at time t1, first control signal IGa rises to H level correspondingly. Thereby, the first switching element 313 is turned on (at this time, since the energy input period signal IGw is at the L level, the second switching element 314 is off). Then, the flow of the primary current in the primary winding 311a starts. Thereby, the ignition coil 311 is charged.

  While the ignition signal IGt rises to the H level, the rectangular-wave-pulsed third control signal IGc is input to the third control terminal 315G in the third switching element 315. When the third switching element 315 is turned on, energy is stored in the energy storage coil 316. Further, the stored energy is released from the energy storage coil 316 and stored in the capacitor 317 when the third switching element 315 is turned off. Thus, energy is stored in the capacitor 317 via the energy storage coil 316 by turning on and off the third switching element 315, and the voltage Vdc rises in a stepped manner. Such accumulation of energy in the capacitor 317 ends by time t2.

  After that, when the first switching element 313 is turned off by the first control signal IGa falling from the H level to the L level at time t2, the primary current that has been flowing through the primary winding 311a until then is changed. It is cut off suddenly. Then, the ignition coil 311 is discharged, and a discharge current that is a large secondary current is generated in the secondary winding 311b. As a result, ignition discharge is started at the spark plug 19.

  After ignition discharge starts at time t2, in conventional discharge control (or under operating conditions in which the energy input period signal IGw is maintained at L level without being raised to H level), a broken line Transition as indicated by. In this case, the discharge current approaches zero over time and attenuates to such an extent that the discharge cannot be maintained. Thereby, ignition discharge is complete | finished. Note that the magnitude of the discharge energy (energy applied to the ignition plug 19) in this case corresponds to the area inside the triangle indicated by the broken line in the time chart of the secondary current I2 in FIG.

  In this regard, in the present embodiment, the energy input period signal IGw is raised to the H level at time t3 immediately after time t2. Correspondingly, the second switching element 314 is turned on (second control signal IGb = H level) when the third switching element 315 is off (third control signal IGc = L level). Then, the stored energy of the capacitor 317 is released from the capacitor 317, and the above-mentioned input energy is supplied to the primary winding 311a from the low voltage side terminal side. Thereby, the primary current resulting from the input energy flows during ignition discharge (induction discharge). That is, the additional amount accompanying the flow of the primary current due to the input energy is superimposed on the discharge current that has flowed between the times t2 and t3.

  Such superimposition (addition) of the primary current is performed every time the second switching element 314 is turned on after time t3 (until t4). That is, as shown in FIG. 4, each time the second control signal IGb rises, the primary current (I1) is sequentially added by the energy stored in the capacitor 317, and the discharge current (I2) is correspondingly increased. Added sequentially. The magnitude of the discharge energy in this case corresponds to the area (integrated value) between t2 and t4 in the time chart of the secondary current I2 in FIG. That is, the input energy described above corresponds to an amount obtained by subtracting the area of the triangle indicated by the broken line from the area between t2 and t4.

  As described above, in the present embodiment, it is possible to secure the discharge current satisfactorily to such an extent that the ignition discharge can be maintained by such input energy. In this specific example, the time interval between the times t2 and t3 is appropriately determined by the electronic control unit 32 based on the engine rotational speed Ne and the intake air amount Ga so that the so-called “blown out” does not occur ( Shall be set (using a map etc.).

  As is well known, under high load or high speed operation conditions (intake pressure Pa: high, engine speed Ne: high, throttle opening THA: high, EGR rate: high, air-fuel ratio: lean) The “disappearance” tends to occur due to the flow velocity of the air flow in the cylinder 11b, leaning, or the like. In this regard, the energy storage state in the capacitor 317 during the time t1 to t2 when the ignition signal IGt rises to the H level can be controlled by the on-duty ratio of the third control signal IGc. In addition, as the stored energy in the capacitor 317 increases, the input energy every time the second switching element 314 is turned on also increases.

  Therefore, in the present embodiment, a high load or high rotation operation condition in which “blown out” is likely to occur (intake pressure Pa: high, engine rotation speed Ne: high, throttle opening THA: large, EGR rate: high, air-fuel ratio : Lean) and the duty ratio of the third control signal IGc is set higher as the time from the start of ignition elapses. Thereby, according to the driving | running state of the engine 11, the energy storage amount in the capacitor | condenser 317 and the amount of input energy can be set appropriately, and while suppressing blowing-off, the spark plug 19 by power saving or useless spark energy is suppressed. Electrode consumption can be suppressed. FIG. 5 shows a case where the duty ratio of the third control signal IGc is lower than that in FIG. 4 under a low load or low rotation operation condition in which “blown out” is unlikely to occur.

  Further, as described above, the flow state of the discharge current during ignition discharge can be appropriately controlled by adjusting the amount of stored energy released from the capacitor 317 by turning the second switching element 314 on and off. Therefore, in the present embodiment, the duty ratio in the second control signal IGb is set to be variable. Specifically, the second control signal IGb is generated so that the duty ratio increases at an increase rate ΔDUTY (is set to increase as the load becomes higher or the rotation speed is higher) as time elapses. As a result, as shown in FIG. 4, the discharge current is maintained at a predetermined value I2th or more.

  As described above, in the configuration of the present embodiment, it is possible to satisfactorily control the flow state of the discharge current corresponding to the flow state of the gas in the cylinder 11b so that “blown out” does not occur. Become. Therefore, according to the present embodiment, the occurrence of “blown out” and the accompanying loss of ignition energy are satisfactorily suppressed by a simple device configuration. That is, according to the present embodiment, it is possible to satisfactorily stabilize the combustion state of the fuel mixture while suppressing as much as possible the increase in physique and manufacturing cost in the ignition control device 30 (particularly the ignition circuit unit 31). It becomes possible.

  In particular, in the configuration of the present embodiment, energy is input from the low voltage terminal side (first switching element 313 side) of the primary winding 311a. For this reason, it is possible to input energy at a lower pressure than when energy is input from the secondary winding 311b side.

  In this regard, if energy is input from the high voltage side terminal of the primary winding 311a at a voltage higher than the output voltage of the DC power supply 312, the efficiency deteriorates due to the current flowing into the DC power supply 312. On the other hand, according to the configuration of the present embodiment, as described above, since energy is input from the low voltage terminal side of the primary winding 311a, energy can be input to the primary winding 311a most easily and efficiently. An excellent effect of being able to be produced.

<Modification>
Hereinafter, some typical modifications will be exemplified. In the following description of the modified examples, the same reference numerals as those in the above embodiment can be used for portions having the same configurations and functions as those described in the above embodiment. And about description of this part, the description in the above-mentioned embodiment shall be used suitably in the range which is not technically consistent. Needless to say, the modifications are not limited to those listed below. In addition, a part of the above-described embodiment and all or a part of the plurality of modified examples can be combined appropriately as long as they are technically consistent.

  The present invention is not limited to the specific configuration exemplified in the above embodiment. That is, for example, some functional blocks of the electronic control unit 32 can be integrated with the driver circuit 319. Alternatively, the driver circuit 319 can be divided for each switching element. In this case, when the first control signal IGa is the ignition signal IGt, the ignition signal IGt is directly output from the electronic control unit 32 to the first control terminal 313G in the first switching element 313 without passing through the driver circuit 319. Also good.

  Further, the IGa signal and the IGc signal do not necessarily have to coincide with each other. For example, the driver circuit 319 may first create and output only the IGc signal in synchronization with the rise of the IGt signal, and output the IGa signal with a slight delay. That is, the IGa signal may be delayed from the IGc signal. Thereby, the energy stored in the capacitor 317 can be increased. On the other hand, the IGc signal may be delayed from the IGa signal.

  The present invention is not limited to the specific operation exemplified in the above-described embodiment. For example, ΔDUTY may be set based on one of the intake pressure Pa and the engine speed Ne. ΔDUTY was arbitrarily selected from a number of engine parameters such as intake pressure Pa, engine speed Ne, throttle opening THA, EGR rate, air-fuel ratio, intake air amount Ga, accelerator operation amount ACCP, and the like. It may be set based on things.

  The duty ratio of the second control signal IGb may be constant during one combustion cycle (specifically, between times t3 and t4). In this case, the duty ratio is set based on the engine parameter as in the above specific example. In this case, the duty ratio DUTY based on the engine parameters is set using a “DUTY map” similar to the “ΔDUTY map” in FIG.

  ΔDUTY may include not only the increasing direction but also the subtracting direction. That is, the duty ratio of the second control signal IGb may be set so as to increase or decrease during one combustion cycle. As a result, it is possible to realize an optimum input energy pattern according to the operation state (that is, blow-off is unlikely to occur).

  Further, instead of the engine parameter, other information that can be used to generate the second control signal IGb and the third control signal IGc may be output from the electronic control unit 32 to the driver circuit 319.

  Instead of, or together with, the duty control of the third control signal IGc exemplified in the above-described embodiment, the waveform of the energy input period signal IGw (the rise timing of t3 and / or the period between t3-t4 in FIG. 3 and the like) ), The input energy may be variable. In this case, instead of or together with the driver circuit 319, the electronic control unit 32 corresponds to the “control unit” of the present invention.

  The circuit configuration for supplying input energy from the low voltage side terminal side in the primary winding 311a (circuit configuration connected to the second power supply side terminal 314D in the second switching element 314) is shown in the above embodiment. It is not limited to the specific example. That is, for example, such a circuit configuration may be an insulated DC-DC converter or a forward converter. Alternatively, it may be a high voltage battery mounted on a so-called hybrid vehicle or the like.

  Other modifications not specifically mentioned are naturally included in the technical scope of the present invention without departing from the essential part of the present invention. In addition, in each element constituting the means for solving the problems of the present invention, elements expressed in terms of function and function are specific configurations disclosed in the above-described embodiments and modifications, and equivalents thereof. In addition to objects, any configuration capable of realizing the action / function is included.

  DESCRIPTION OF SYMBOLS 11 ... Engine, 11b ... Cylinder, 19 ... Spark plug, 30 ... Ignition control device, 31 ... Ignition circuit unit, 32 ... Electronic control unit, 311 ... Ignition coil, 311a ... Primary winding, 311b ... Secondary winding, 312 ... DC power supply, 313 ... first switching element, 313C ... first power supply side terminal, 313E ... first ground side terminal, 313G ... first control terminal, 314 ... second switching element, 314D ... second power supply side terminal, 314G ... second control terminal, 314S ... second ground side terminal, 315 ... third switching element, 315C ... third power supply side terminal, 315E ... third ground side terminal, 315G ... third control terminal, 316 ... energy storage coil, 317: Capacitor, 319 ... Driver circuit, IGa ... First control signal, IGb ... Second control signal, IGc ... Third control signal, IGt ... Fire signal, IGw ... energy charge period signal.

Claims (6)

In an ignition control device (30) configured to control the operation of a spark plug (19) provided to ignite a fuel mixture in a cylinder (11b) of an internal combustion engine (11),
A primary winding (311a) and a secondary winding (311b) are provided, and the secondary winding connected to the spark plug is connected to the spark plug by increasing / decreasing the primary current flowing through the primary winding. An ignition coil (311) configured to generate a secondary current
A direct-current power source (312) having a non-grounded output terminal connected to one end of the primary winding so that the primary current flows through the primary winding;
The first control terminal (313G), the first power supply side terminal (313C), and the first ground side terminal (313E) have the first control signal input to the first control terminal based on the first control signal. A semiconductor switching element configured to control on / off of energization between a power supply side terminal and the first ground side terminal, wherein the first power supply side terminal is connected to the other end side of the primary winding. And a first switching element (313) having the first ground side terminal connected to the ground side,
The second control terminal (314G), the second power supply side terminal (314D), and the second ground side terminal (314S) have the second control signal input to the second control terminal based on the second control signal. A semiconductor switching element configured to control on / off of energization between a power supply side terminal and the second ground side terminal, wherein the second ground side terminal is connected to the other end side of the primary winding. A second switching element (314),
The third control terminal (315G), the third power supply side terminal (315C), and the third ground side terminal (315E) have the third control terminal based on the third control signal input to the third control terminal. A semiconductor switching element configured to control on / off of energization between a power supply side terminal and the third ground side terminal, wherein the third power supply side terminal is the second power supply side of the second switching element. A third switching element (315) connected to the terminal and having the third ground side terminal connected to the ground side;
An inductor interposed in a power line connecting the non-grounded output terminal of the DC power supply and the third power supply side terminal of the third switching element, and stores energy when the third switching element is turned on And an energy storage coil (316) provided to be released when the third switching element is turned off,
The energy storage coil is connected in series between the non-grounded output terminal and the ground side of the DC power supply, and stores the energy released from the energy storage coil when the third switching element is turned off. A capacitor (317) provided as follows:
During the ignition discharge of the spark plug started by turning off the first switching element, the third switching element is turned off and the second switching element is turned on to release energy from the capacitor and thereby the primary winding. A control unit (319) provided to control the second switching element and the third switching element to supply the primary winding from the other end side in order to pass the primary current through a wire; )When,
With
The ignition control device, wherein the control unit variably sets a duty ratio in the second control signal.   The ignition control device according to claim 1, wherein the control unit sets the duty ratio according to an operating state of the internal combustion engine.   The ignition control device according to claim 2, wherein the operating state of the internal combustion engine includes at least an engine speed.   The ignition control device according to any one of claims 1 to 3, wherein the control unit variably sets the duty ratio in one combustion cycle.   The ignition control device according to claim 4, wherein the control unit increases the duty ratio as time elapses.   The ignition control device according to claim 5, wherein the control unit variably sets an increase rate of the duty ratio with time.

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