JP2004308518A - Internal combustion engine and control method for internal combustion engine - Google Patents

Abstract

An object of the present invention is to prevent a deposit of fuel from accumulating on the tip of an injector.
An internal combustion engine (1) having an injector (123) for injecting fuel into a combustion chamber (110), the intake air amount adjusting means for adjusting an amount of air supplied to the combustion chamber (110). (104, 203) and an engine control unit (200) for controlling the amount of air in the intake air amount adjusting means (104, 203). The engine control unit (200) reduces the amount of air supplied to the combustion chamber from a reference amount for a predetermined period after the fuel for combustion is injected from the injector (123) into the combustion chamber (110). By this control, the fuel at the tip of the injector (123) is sucked and the occurrence of deposit is prevented.
[Selection diagram] Fig. 1

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an internal combustion engine such as a direct injection engine, and more particularly, to an internal combustion engine that prevents deposits from being deposited at the tip of an injector.
[0002]
[Prior art]
In the injector that supplies fuel to the combustion chamber of an internal combustion engine, the fuel remaining at the tip of the injector is heated, causing a substance contained in the liquid phase component to undergo a dehydrogenation reaction or a polymerization reaction, and a solidified deposit remains. It was a problem. The deposit accumulates in the sack at the tip of the injector or closes the injection hole, which hinders fuel injection.
[0003]
Conventionally, techniques for preventing generation and accumulation of deposits have been devised. For example, Japanese Patent Application Laid-Open No. 2002-130022 discloses that the number of revolutions of an engine is detected, and at low speed, that is, when the fuel injection interval is long and the fuel at the tip of the injector tends to solidify during that time, the combustion chamber A technique has been disclosed in which the ignition timing is controlled to a retard side to make the combustion slow, thereby lowering the temperature at the tip of the injector and preventing the deposit from remaining (Patent Document 1).
[0004]
Japanese Patent Application Laid-Open No. 2002-48034 discloses a technique in which a step and a fuel escape groove are provided in a nozzle plate of an injector so that fuel is separated from the nozzle by surface tension and discharged through the escape groove ( Patent Document 2).
[0005]
[Patent Document 1]
JP 2002-130022 A
[0006]
[Patent Document 2]
JP 2002-48034 A
[0007]
[Problems to be solved by the invention]
However, the technology for controlling the ignition timing as disclosed in Patent Document 1 allows slow combustion, and thus has a problem that the combustion efficiency is reduced and the fuel efficiency is deteriorated. Further, in the nozzle structure disclosed in Patent Document 2, the remaining fuel is separated from the nozzle and stagnates, but the fuel before being discharged becomes a deposit due to a rise in temperature, and it is avoided that the fuel may eventually be blocked. I couldn't.
[0008]
[Means to solve the problem]
Therefore, an object of the present invention is to provide an internal combustion engine capable of preventing deposits from adhering to an injection valve and a control method thereof in order to solve the above-mentioned problem.
[0009]
According to a first aspect of the present invention, there is provided an internal combustion engine having an injection valve for injecting fuel into a combustion chamber, wherein an intake air amount adjusting means for adjusting an amount of air supplied to the combustion chamber, and an intake air amount adjustment device. Control means for controlling the amount of air in the means, wherein the control means reduces the amount of air supplied to the combustion chamber from a reference amount for a predetermined period after fuel for combustion is injected from the injection valve into the combustion chamber. It is characterized.
[0010]
According to the above configuration, in order to properly mix and ignite fuel and air in the normal combustion chamber and ignite, air is supplied to the combustion chamber with a reference amount. Decrease. When the air amount is reduced, a negative pressure is generated at the tip of the injection valve, so that the fuel remaining at the tip of the injection valve is sucked by the negative pressure. Therefore, the fuel causing the deposit is not left at the tip of the injection valve at the time of combustion, so that the deposit does not occur even if the temperature of the tip of the injection valve rises.
[0011]
The period for reducing the air amount may be immediately after the combustion fuel injection or after a short interval. The fuel may be removed before the conditions under which a deposit can occur.
[0012]
Here, in the present invention, the “injection valve” means a fuel supply structure such as an injector, but the injection valve does not necessarily need to be provided directly in the combustion chamber (for example, a direct injection engine). This is because, even if the injection valve is configured to inject fuel into a place other than the combustion chamber, for example, into the suction pipe, the present invention is applicable as long as the structure can generate a deposit due to a temperature rise.
[0013]
"Intake air amount adjusting means" means all structures capable of changing the amount of air supplied into the combustion chamber, and corresponds to a throttle valve or an intake valve configured to be capable of restricting a flow rate.
[0014]
“Control means” means a computer device (engine control unit or the like) configured to be able to execute the operation of the present invention by a software program, but does not necessarily need to be software-controlled and can perform the same control. It may be configured as a hardware structure.
[0015]
The “reference amount” refers to an average amount of air flow per unit time to be taken for intake into the combustion chamber, and an appropriate reference amount differs depending on the internal combustion engine.
[0016]
The “predetermined period” may be continued immediately after the fuel injection, or may be slightly after the fuel injection. It is sufficient if the pressure in the sack can be reduced to a negative pressure before the fuel amount becomes such that a deposit can be generated after the fuel injection.
[0017]
Here, the control means sets a period in which the amount of air is reduced to a period in which the fuel in the sack at the tip of the direct injection valve is sufficient to be sucked by the negative pressure. With this setting, the fuel in the sack is not sucked and remains in the sack, so that no deposit occurs even when the temperature of the injection valve becomes high.
[0018]
The length of the predetermined period varies depending on the degree of the negative pressure and the structure of the injection valve. The predetermined period may be a predetermined fixed time or may correspond to the rotation angle of the crankshaft of the internal combustion engine.
[0019]
In the present invention, it is preferable that the control means increases the amount of air supplied to the combustion chamber from the reference amount for a predetermined period after the period in which the amount of air is reduced. According to such a configuration, it is possible to compensate for the intake air amount which has been reduced as a whole due to the reduction of the air amount in order to suck the fuel which may cause a deposit, and it does not hinder proper combustion. is there. For example, the control means sets the period in which the amount of air is increased to a period in which the amount of air that has become smaller than the required amount of intake air by reducing the amount of air can be compensated. According to such a configuration, at least appropriate combustion in the combustion chamber can be ensured.
[0020]
The period in which the air amount is increased may be continuous with the period in which the air amount is reduced, or the air amount may be increased after returning to the reference amount of air supply for a while. It is sufficient that air can be replenished in time for compression and combustion of the air-fuel mixture.
[0021]
Further, in the present invention, it is preferable to further include a crank angle detecting means for detecting an angle of the crank shaft. At this time, the control means controls the intake air amount adjusting means based on the rotation angle of the crankshaft detected by the crank angle detecting means. According to such a configuration, it is possible to know an appropriate timing for adjusting the amount of intake air by detecting the angle of the crankshaft. With such a configuration, the period during which the amount of air is reduced or increased varies according to the rotational angular velocity of the crankshaft, and it is not necessary to adjust the period.
[0022]
The timing can also be known by detecting the rotation angle of a camshaft or the like that moves the intake valve or the exhaust valve. That is, the timing of the minute fuel supply can be controlled by detecting and referring to the movement of a member that periodically operates in response to the operation of the internal combustion engine or the signal itself for periodically operating the internal combustion engine.
[0023]
A second invention for achieving the above object is an internal combustion engine provided with an injection valve for injecting fuel into a combustion chamber, wherein a fuel amount adjustment means for adjusting an amount of fuel supplied to the combustion chamber via the injection valve, Control means for controlling the fuel amount in the fuel amount adjusting means, wherein the control means supplies a very small amount of fuel to the injection valve after the fuel for combustion is injected from the injection valve into the combustion chamber. I do.
[0024]
According to the above configuration, a small amount of fuel is injected into the injector after the fuel for combustion is injected, so that the sack of the injector is filled with fuel again. Since the deposit is generated by adding heat in a temperature range in which the deposit can be generated when the residual amount of fuel is reduced, if the sack is refilled with fuel in the temperature range, the deposit can be reduced. No longer occurs. Further, since the temperature at the tip of the injection valve is further reduced by the injection of a very small amount of fuel, deposits are less likely to occur.
[0025]
Even if the amount of fuel in the sack becomes such that the deposit can be generated after the ignition of the combustion chamber, the deposit disappears due to the high temperature in the combustion chamber, and the solid phase component does not remain. For this reason, it is preferable to maintain the fuel amount in the sac at a level where deposits are unlikely to occur before fuel ignition.
[0026]
Here, the term "small amount" means an amount of fuel that does not contribute to the combustion of fuel (that is, only the combustion fuel is sufficient for combustion) but is sufficient to prevent deposits in the sack. Deposits occur when the temperature is within a predetermined temperature range and there is fuel remaining below a certain level.Therefore, no deposit will occur as long as a sufficient amount of fuel remains in the sack. .
[0027]
It should be noted that the fuel supply in a small amount is performed after the fuel injection until the fuel in the sack is heated to a high temperature at which no deposit is generated by ignition of the combustion chamber (that is, a period in a temperature range in which the deposit can be generated). It is carried out at a timing that is always higher than the limit amount at which a deposit can occur. Therefore, it is preferable that the fuel injection be performed shortly before the fuel in the sac reaches the limit amount after the fuel injection.
[0028]
Here, in the second aspect of the present invention, the fuel injection valve further includes an injection valve temperature detecting means for detecting a temperature of the injection valve tip, and the control means determines that the temperature of the injection valve tip detected by the injection valve temperature detection means is higher than a predetermined temperature In this case, it is preferable to supply a very small amount of fuel. According to the configuration described above, the fuel is refilled in the sack after detecting whether or not the condition is such that a deposit can be generated, so that the generation of the deposit can be reliably prevented. Conversely, when the possibility of deposit generation is low due to a decrease in temperature, it is possible to dispense with supplying a very small amount of fuel.
[0029]
Here, the "predetermined temperature" is, for example, a temperature at which a deposit may occur depending on the amount of fuel remaining in the sack, and if the temperature is lower than this, it is not necessary to refill the fuel. No deposit will occur. The predetermined temperature may be a value that detects a temperature range in which a deposit can be generated, or may be a value that is detected as an index of the remaining fuel amount in the sack. That is, after the fuel is injected, the amount of fuel remaining at the tip of the injector decreases in accordance with the temperature decrease at the tip of the injector. This temperature detection can also be used as an index for determining whether or not this fuel amount has reached a limit amount at which a deposit can occur.
[0030]
Here, in the second aspect of the present invention, it is preferable that a crank angle detecting means for detecting an angle of the crankshaft is further provided. At this time, the control means supplies a small amount of fuel when the rotation angle of the crankshaft detected by the crank angle detection means reaches a predetermined angle. According to such a configuration, an appropriate timing for supplying a very small amount of fuel can be known by detecting the angle of the crankshaft.
[0031]
The timing can also be known by detecting the rotation angle of a camshaft or the like that moves the intake valve or the exhaust valve. That is, the timing of the minute fuel supply can be controlled by detecting and referring to the movement of a member that periodically operates in response to the operation of the internal combustion engine or the signal itself for periodically operating the internal combustion engine.
[0032]
According to a third aspect of the present invention, there is provided an internal combustion engine provided with an injection valve for injecting fuel into a combustion chamber, wherein a fuel amount adjusting means for adjusting an amount of fuel supplied to the combustion chamber via the injection valve, Control means for controlling the fuel amount in the amount adjusting means, and injection valve temperature detecting means for detecting the temperature at the tip of the injection valve, wherein the control means controls the fuel for combustion supplied from the injection valve into the combustion chamber a plurality of times. When the temperature at the tip of the injection valve detected by the injection valve temperature detecting means reaches a predetermined temperature, the fuel is supplied in the second and subsequent times.
[0033]
According to the above configuration, after the fuel for combustion is supplied, the fuel in the sack at the tip of the injection valve gradually decreases, but the temperature at the tip of the injection valve and the amount of fuel remaining in the sack correspond to some extent, so that no deposit occurs. If the fuel is injected in the presence of a certain amount of residual fuel, the temperature in the sack is reduced at a stretch and the sack is filled with the fuel, so that no deposit occurs.
[0034]
Here, in the third aspect of the invention, it is preferable to further include a crank angle detecting means for detecting an angle of the crankshaft. At this time, when the rotation angle of the crankshaft detected by the crank angle detection means has reached a predetermined angle, the control means causes the fuel to be supplied for the second and subsequent times. According to such a configuration, by detecting the angle of the crankshaft, it is possible to know an appropriate timing for supplying the second and subsequent fuels.
[0035]
The timing can also be known by detecting the rotation angle of a camshaft or the like that moves the intake valve or the exhaust valve. That is, the timing of the divided fuel supply can be controlled by detecting and referring to the movement of a member that periodically operates in response to the operation of the internal combustion engine or the signal itself for periodically operating the internal combustion engine.
[0036]
A control method for an internal combustion engine according to a first aspect of the present invention is a control method for an internal combustion engine including an injection valve for injecting fuel into a combustion chamber, wherein the step of injecting fuel for combustion from the injection valve into the combustion chamber includes the steps of: Reducing the amount of air supplied to the combustion chamber from the reference amount for a predetermined period from the supply of the fuel for use.
[0037]
According to the above process, the amount of air supplied after the fuel injection from the injection valve becomes smaller than the reference amount and a negative pressure is generated at the tip of the injection valve, so that the fuel remaining at the tip of the injection valve is sucked by the negative pressure. Therefore, the fuel causing the deposit is not left at the tip of the injection valve at the time of combustion, so that the deposit does not occur even if the temperature of the tip of the injection valve rises.
[0038]
The control method for an internal combustion engine according to the first invention further includes a step of increasing the amount of air supplied to the combustion chamber from a reference amount for a predetermined period after the step of reducing the amount of air. According to such a method, the intake air amount reduced as a whole by reducing the air amount for sucking the fuel which may cause the deposit can be compensated, and proper combustion is not hindered.
[0039]
A control method for an internal combustion engine according to a second aspect of the present invention is a control method for an internal combustion engine including an injection valve for injecting fuel into a combustion chamber, wherein the step of injecting fuel for combustion from the injection valve into the combustion chamber includes the steps of: Supplying a very small amount of fuel to the injection valve after a predetermined period of time after the fuel for combustion is injected from the valve into the combustion chamber.
[0040]
According to the above-described process, a small amount of fuel is injected into the injector after the fuel for combustion is injected, so that the sack of the injector is filled with fuel again. Since the deposit is generated by adding heat in a temperature range in which the deposit can be generated when the residual amount of the fuel decreases, if the sack is controlled to refill the fuel within the temperature range, the deposit can be reduced. No longer occurs.
[0041]
A control method for an internal combustion engine according to a third aspect of the present invention is a control method for an internal combustion engine including an injection valve for injecting fuel into a combustion chamber, and supplies a first combustion fuel to the combustion chamber via the injection valve. And supplying the second and subsequent combustion fuels when the temperature at the tip of the injection valve reaches a predetermined temperature.
[0042]
According to the above process, the fuel in the sack at the tip of the injection valve gradually decreases after the supply of fuel for combustion, but the deposit at the tip of the injection valve and the amount of fuel remaining in the sack correspond to some extent, so that no deposit occurs. If fuel is injected when there is some residual fuel, the temperature in the sack is reduced at once, and the sack is filled with fuel, so that a deposit is generated in a temperature range where a deposit can occur. Fuel reduction to volume is prevented.
[0043]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0044]
(1st Embodiment)
The first embodiment of the present invention is the internal combustion engine according to the first invention, and particularly controls an amount of air supplied to a combustion chamber of a direct injection engine. FIG. 1 shows a system conceptual diagram of the direct injection engine of the present embodiment. The following embodiments are examples in which the present invention is applied to a direct injection engine, and the present invention is not limited to these structures.
[0045]
As shown in FIG. 1, the direct injection engine 1 of the present embodiment includes an intake port 101, an air cleaner 102, an intake pipe 103, a throttle valve 104, a surge tank 105, and an intake manifold 106 as an intake system.
[0046]
The air cleaner 102 is for filtering dust in the air taken in. The throttle valve 104 according to the present invention has a valve structure for controlling the flow rate of air flowing through the intake pipe 103. The surge tank 105 equalizes the pressure of the air supplied into the combustion chamber 110. The intake manifold 106 is a pipe that guides air into the combustion chamber 110.
[0047]
The exhaust system includes an exhaust manifold 130, a three-way catalyst 131, and an exhaust pipe 132. The three-way catalyst 131 is a structure for reducing exhaust gas.
[0048]
FIG. 1 shows only a partial cross-sectional view of the main body of the direct injection engine 1, and includes a combustion chamber 110, a piston 111, an arm 112, a crankshaft 113, a rotary plate 114, a spark plug 115, an intake valve 116, An exhaust valve 117, a cylinder head 120, a camshaft 121, an ignition coil 122, and an injector 123 are provided.
[0049]
The combustion chamber 110 burns a mixture of fuel supplied from the injector 123 and air supplied from the intake manifold 106. A space for a cooling water jacket is formed around the combustion chamber 110, but is omitted in the figure for simplicity. The piston 111 is slidable in the combustion chamber by expansion due to combustion in the combustion chamber 110, and its power is transmitted to a crankshaft 113 through an arm 112. The rotating plate 114 rotates together with the crankshaft 113, and can indicate the rotation angle of the crankshaft. The ignition plug 115 ignites when a high voltage is supplied from the ignition coil 122, and ignites the air-fuel mixture. The intake valve 116 is configured to open in a predetermined angular range of the crankshaft, that is, in the intake stroke, in accordance with the rotation of the intake camshaft 121, and to supply a mixture of air and fuel to the combustion chamber 110. It can be guided inside. The exhaust valve 117 is configured to rise to the exhaust camshaft 121 and open in a predetermined crankshaft angle range, that is, in an exhaust process, so that the combustion gas can be exhausted. . The injector 123 according to the present invention can supply an amount of fuel corresponding to the control of an engine control unit (hereinafter, referred to as “ECU”) 200.
[0050]
The control system includes ECU 200, aero flow sensor 201, throttle position sensor 202, throttle motor 203, surge tank pressure sensor 204, injector tip temperature sensor 205, cam position sensor 206, crank position sensor 207, which are control means according to the present invention. And so on.
[0051]
The ECU 200 has a configuration as a known microcomputer device, and includes, for example, a CPU (Central Processing Unit), a memory, an interface circuit, and the like. In particular, the ECU 200 executes a software program for performing the control method according to the present invention, and is configured to be operable as the internal combustion engine of the present invention.
[0052]
Specifically, the ECU 200 can detect the intake air amount by referring to the detection signal of the aeroflow sensor 201. The ECU 200 can detect the opening of the throttle valve 104 by referring to the detection signal of the throttle position sensor 202. On the other hand, the ECU 200 drives the throttle motor 203 to arbitrarily change the opening of the throttle valve 104. It is configured to be able to. The ECU 200 can detect the pressure in the surge tank 105 by referring to the detection signal from the surge tank pressure sensor 204. Also, by referring to the detection signal from the injector tip temperature sensor 205, the ECU 200 can indirectly detect the tip temperature of the injector 123, that is, the remaining amount of fuel remaining at the injector tip. The cam position sensor 206 can detect the rotation angle of the camshaft 121 that opens and closes the intake valve 116 and the exhaust valve 117, and the crank position sensor 207 can detect the rotation angle of the rotating plate 114 that rotates together with the crankshaft 113. It has become. By referring to the detection signals from the cam position sensor 206 and the crank position sensor 207, the ECU 200 can detect which step of the two-rotation one-cycle engine is in.
[0053]
The structure of the tip of the injector 123 will be described with reference to FIG. The distal end portion of the injector 123 is configured such that the holder 1232 surrounds the needle 1231. Fuel is supplied from around the needle 121. An injection hole 1233 is provided in the holder 1232 so that fuel can be injected into the combustion chamber 110. A region surrounded by the needle 121 and the holder 1232 is a sack 1234, which is a region where a small amount of fuel usually remains after fuel injection.
[0054]
Next, the operation of the first embodiment will be described. FIG. 2 shows a method of controlling the amount of intake air according to the first embodiment, and shows the relationship between the opening of the throttle valve 104 with respect to the angle of the crankshaft and the surge tank pressure that increases and decreases with the angle. The angle of the crankshaft indicates a relative angle when the angle of the crankshaft at the top dead center is set to zero.
[0055]
As shown in FIG. 2, in the first embodiment, the ECU 200 supplies the fuel into the combustion chamber 110 for a predetermined period (crank angles A1 to A2) after the fuel for combustion is injected from the injector 123 into the combustion chamber 110. The amount of air to be reduced is reduced from the reference amount (throttle valve opening S0) to the throttle valve opening S1. Further, the ECU 200 changes the amount of air supplied into the combustion chamber 110 from the reference amount (S0) to the throttle valve opening S2 for a predetermined period (angles A2 to A3 of the crankshaft 113) after the air amount is reduced. Is increasing.
[0056]
The control method of the first embodiment will be described in detail with reference to the flowchart shown in FIG. As a premise, it is assumed that the throttle valve 104 is controlled to the opening S0 for supplying the air amount as a reference amount during the period from the start of the intake stroke to the fuel injection stroke.
[0057]
First, the ECU 200 determines whether fuel injection has been completed with reference to the camshaft position sensor 206 and / or the crank position sensor 207 (S01). If the fuel injection has not been completed (S01: N), the process belongs to another process and another process corresponding to the process is performed (S07).
[0058]
On the other hand, when the fuel injection is completed (S01: Y), the ECU 200 closes the throttle valve 104 to the opening degree S1 while driving the throttle motor 203 and monitoring the detection signal of the throttle position sensor 202 (S02). . The angle of the crankshaft 113 at this time is A1. As the opening of the throttle valve 104 decreases, the air flow rate decreases. At this time, the fuel remains in the sack 1234 at the tip of the injector 123 due to the fuel injection, and is in a state of gradually decreasing. If the amount of fuel is reduced as it is, the temperature at the tip of the injector 123 is high and deposits are likely to occur. However, since the opening degree of the throttle valve 104 is reduced to S1 at a stretch, the pressure in the intake pipe 103 and the surge tank 105 is drastically reduced, and the fuel in the sac 1234 is sucked out by the intake negative pressure and hardly remains in the sac. It is determined in advance by experiments or the like how long such an intake negative pressure should be carried out so that the fuel in the sack 124 can be substantially sucked out. The ECU 200 operates so that the intake negative pressure is generated only in the rotation range (A1 to A2) of the crankshaft 113 corresponding to a period sufficient for fuel removal. That is, as long as the angle of the crankshaft 113 has not reached A2 (S03: N), the ECU 200 maintains the opening of the throttle valve 104 at S1.
[0059]
When the angle of the crankshaft 113 becomes A2 (S03: Y), the ECU 200 opens the throttle valve 104 at once from the reference opening S1 to S2 which is further opened (S04). If the throttle valve 104 is maintained at such an opening, a sufficient amount of air is supplied to the surge tank 105 and the pressure in the surge tank 105 increases. Since the air flow rate was limited to obtain the intake negative pressure in step S02, the originally required air amount was not supplied to the surge tank 105 until the angle of the crankshaft 113 reached A2. However, since the opening degree of the throttle valve 104 is increased to supply a large amount of air, the insufficient air amount is compensated for. It is appropriate that the amount of air to be compensated is equal to the amount of air that was insufficient at the intake negative pressure. Therefore, the ECU 200 waits for a period set in advance to supply such an amount of air, that is, until the angle of the crankshaft 113 reaches A3 (S05: N), and when the angle reaches A3. (S05: Y) The opening of the throttle valve 104 is returned to the reference value S0 (S07). Thereafter, other processing is performed according to the process (S07).
[0060]
As described above, according to the first embodiment, since the intake air amount is reduced after the fuel injection, the fuel remaining in the sac 1234 is sucked by the negative pressure generated at the tip of the injector 123. For this reason, the fuel causing the deposit is not left at the tip of the injector 123, so that the deposit can be prevented from being generated regardless of how the temperature at the tip of the injector 123 changes.
[0061]
Further, according to the first embodiment, the period during which the amount of air is reduced is set to a period during which the fuel in the sac 1234 from the angle A1 to the angle A2 is sufficient for the fuel in the sac 1234 to be sucked by the negative pressure. It is possible to prevent the fuel inside from being sucked almost completely and remaining in the sack.
[0062]
According to the first embodiment, the amount of air supplied into the combustion chamber 110 is increased from the reference amount S0 for a predetermined period after the period in which the amount of air is reduced. It is possible to compensate for the intake air amount that has been reduced as a whole as the opening degree of the valve 104 is reduced, and to maintain appropriate combustion.
[0063]
Furthermore, according to the first embodiment, since the crank position sensor 207 detects the angle of the crankshaft 113 and opens and closes the throttle valve 104 correspondingly, the air amount is adjusted at an appropriate timing. Can be.
[0064]
(2nd Embodiment)
The second embodiment of the present invention relates to the internal combustion engine according to the second aspect of the present invention, in which a very small amount of fuel is supplied again after direct fuel supply in a direct injection engine. The configuration of the direct injection engine of the present embodiment is the same as that of the first embodiment, and the description thereof will be omitted.
[0065]
Next, the operation of the second embodiment will be described. FIG. 4 shows a fuel supply control method according to the second embodiment, and shows a relationship between a change in the remaining amount of fuel in the sac 1234 with respect to the angle of the crankshaft and an injector tip temperature that increases and decreases accordingly. The angle of the crankshaft indicates a relative angle when the angle of the crankshaft at the top dead center is set to zero.
[0066]
As shown in FIG. 4, in the second embodiment, after the fuel for combustion is injected from the injector 123 into the combustion chamber 110, a very small amount of fuel sufficient to fill the fuel from the injector 123 into the sack 1234 again. It supplies fuel.
[0067]
The fuel injection that contributes to the fuel combustion is performed in the range from the crankshaft angle A10 to the crankshaft angle A11 in FIG. During this period, the fuel is supplied to the tip of the injector 123 at a stretch, so that the inside of the sack 1234 has the fuel amount Qf in a state where the fuel is completely filled. However, the fuel in the sack 1234 decreases over time. If the remaining amount of fuel in the sack is equal to or less than the limit amount Qth at which a deposit can be generated, and the temperature at that time is within a temperature range in which a deposit is generated (Tth to T1), that is, as shown by a hatched portion in FIG. A deposit is generated in the area.
[0068]
Therefore, in the present embodiment, before reaching such a limit amount Qth, a small amount of fuel is supplied again to fill the inside of the sack 1234 with fuel, thereby preventing generation of a deposit. For this reason, when a configuration capable of measuring the fuel remaining amount in the sack is provided, the measured amount may be used. Here, as shown in FIG. Since it corresponds, the remaining fuel amount in the sack is indirectly detected by detecting the injector tip temperature.
[0069]
The control method according to the second embodiment will be described in detail with reference to the flowchart shown in FIG. As a premise, it is assumed that the period from the start of the intake stroke to the fuel injection stroke has been completed according to normal control. At this time, in the sac 1234 at the tip of the injector 123, the fuel gradually decreases and the temperature also gradually decreases. The ECU 200 determines, with reference to the camshaft position sensor 206 and / or the crank position sensor 207, whether or not the remaining fuel amount in the sack has reached the crankshaft angle A12 approaching the limit value Qth (S10). If it has not reached A12 (S10: N), the other processing (S16) is continued. If A12 has been reached (S10: Y), reference is made to a detection signal from the injector tip temperature sensor 205 (S11) to determine whether or not the injector tip temperature indicates that the fuel remaining in the sack is low. Is determined (S12). If the injector tip temperature has not reached the threshold value Tth (S12: N), the other processing (S16) is continued. This threshold value Tth is a value that experimentally indicates that the remaining fuel amount in the sack 1234 is close to the limit value. Here, the detection of the crankshaft angle and the measurement of the injector tip temperature are both performed, but only one of them may be detected. That is, if the angle of the crankshaft changes according to the amount of fuel remaining in the sack at the tip of the injector, the injection timing of a very small amount of fuel can be estimated only by detecting the angle of the crankshaft.
[0070]
If the injector tip temperature has reached the threshold value Tth (S12: Y), a very small amount of fuel is injected (S13). That is, the fuel injection is continued until the crankshaft angle reaches A13 (S14: N), and the fuel injection is stopped when the crankshaft angle reaches A13 (S14: Y) (S15). Here, if the minute amount of fuel injection is only a small amount and does not require quantitative management, the fuel injection may be performed for a predetermined period without detecting the end of injection (crankshaft angle A13). You may comprise. After the minute fuel injection, other processing is continued (S16).
[0071]
According to the second embodiment, the amount of fuel in the sack becomes larger than the limit amount Qth due to the injection of a small amount of additional fuel, thereby making it difficult to generate a deposit.
[0072]
Further, according to the second embodiment, as shown in FIG. 4, the fuel injection lowers the temperature at the tip of the injector at a stretch and falls outside the temperature range in which a deposit can be generated, and furthermore, the deposition is less likely to occur.
[0073]
Furthermore, according to the second embodiment, since the detection of the crankshaft angle and the detection of the injector tip temperature are used together, the fuel injection timing can be accurately controlled.
[0074]
(Third embodiment)
The third embodiment of the present invention relates to the internal combustion engine according to the third aspect of the present invention, and particularly to a direct injection engine in which the supply of combustion fuel is performed in a divided manner. The configuration of the direct injection engine of the present embodiment is the same as that of the first embodiment, and the description thereof will be omitted.
[0075]
Next, the operation of the third embodiment will be described. FIG. 6 shows a fuel supply control method according to the third embodiment, and shows a relationship between a change in the remaining amount of fuel in the sac 1234 with respect to the angle of the crankshaft, and the injector tip temperature which increases and decreases accordingly. The angle of the crankshaft indicates a relative angle when the angle of the crankshaft at the top dead center is set to zero.
[0076]
As shown in FIG. 6, in the third embodiment, the combustion fuel supplied from the injector 123 into the combustion chamber 110 is supplied in a plurality of times. In the second embodiment, the fuel injection contributing to the fuel combustion is performed in the first fuel injection (period from the crankshaft angle A10 to the crankshaft angle A11 in FIG. 4). There are a plurality of fuel injections that contribute to fuel combustion (crankshaft angles A20 to A21 and A22 to A23 in FIG. 6).
[0077]
Specifically, in the first fuel injection, the fuel is supplied to the tip of the injector 123 at a stretch, so that the inside of the sac 1234 becomes the fuel amount Qf in a state where the fuel is completely filled. However, the fuel in the sack 1234 decreases over time. If the remaining amount of fuel in the sack is equal to or less than the limit amount Qth at which a deposit can be generated and the temperature at that time is within a temperature range at which a deposit is generated (Tth to T1), that is, as shown by the hatched portion in FIG. A deposit is generated in the area.
[0078]
Therefore, in the third embodiment, the second combustion fuel injection is performed before reaching the limit amount Qth. Even in the second fuel injection, the inside of the sack 1234 at the tip of the injector 123 is again filled with the fuel, so that the generation of the deposit is prevented. In order to know the second fuel injection timing, if a configuration is provided that can measure the remaining amount of fuel in the sack, the measured amount may be used. Here, similarly to the second embodiment, the remaining fuel amount in the sack is indirectly detected by detecting the injector tip temperature.
[0079]
The control method of the third embodiment will be described in detail with reference to the flowchart shown in FIG. First, the ECU 200 determines whether or not the first fuel injection timing has reached the crankshaft angle A20 with reference to the camshaft position sensor 206 and / or the crank position sensor 207 (S20). If it has not reached A20 (S20: N), the other processing (S29) is continued, and if it has reached A20 (S20: Y), the crankshaft angle becomes A21 (S22: N). ), The first combustion fuel injection is performed (S21).
[0080]
When the first combustion fuel injection is completed (S23), the ECU 200 refers to the detection signal from the injector tip temperature sensor 205 in the same way as in the second embodiment (S24), and determines the injector tip temperature. It is detected whether or not the value Tth has been reached, that is, whether or not the remaining fuel amount in the sack is approaching the limit value (S25). If the injector tip temperature has not reached the threshold value Tth (S25: N), the other processing (S29) is continued, but if the injector tip temperature has reached the threshold value Tth (S25: Y), the second time The fuel injection for combustion is started (S26). Then, the fuel injection is continued until the crankshaft angle reaches A23 (S27: N), and when it reaches A23 (S27: Y), the fuel injection is stopped (S28). After the second fuel injection, other processing is continued (S29).
[0081]
In the above embodiment, the fuel injection for combustion is divided into two times, but may be divided into three or more times. There is no limit to the number of times that the fuel mixture before the ignition can be compressed and the required fuel is supplied into the combustion chamber. If the tip structure of the injector is likely to cause a deposit (for example, the remaining amount of fuel decreases early), it is meaningful to increase the number of times of fuel injection.
[0082]
As described above, according to the third embodiment, the fuel in the sack can always be kept larger than the limit amount Qth in the temperature range in which the deposit is likely to be generated by the fuel injection for combustion divided into a plurality of times, and the deposit is less likely to be generated.
[0083]
In addition, according to the third embodiment, as shown in FIG. 6, the injector tip temperature drops at a stretch by a plurality of fuel injections, and the temperature falls outside the temperature range in which a deposit can be generated.
[0084]
(Other modifications)
The present invention is not limited to the above-described embodiment, and can be variously modified and applied without departing from the spirit thereof. For example, in the above-described embodiment, the control timing of air or fuel is detected by the angle of the crankshaft or the temperature at the tip of the injector. However, another parameter corresponding to the cycle of the internal combustion engine may be used. That is, it is only necessary that the fuel can be controlled so that the remaining fuel amount at the tip of the injector is equal to or more than the limit amount or hardly exists in the temperature range where the deposit is easily generated.
[0085]
【The invention's effect】
According to the present invention, control is performed such that the fuel remaining at the tip of the injection valve after the fuel injection is sucked out by the negative pressure of the air to be extinguished or refilled to an amount that hardly causes a deposit. This can prevent the generation of deposits even in a temperature range in which is likely to occur.
[Brief description of the drawings]
FIG. 1 is a conceptual diagram illustrating a structure of an internal combustion engine according to an embodiment.
FIG. 2 is a diagram illustrating a relationship between a throttle opening and a pressure in a surge tank according to the first embodiment;
FIG. 3 is a flowchart illustrating a control method according to the first embodiment.
FIG. 4 is a diagram illustrating a relationship between an injector tip temperature and a fuel amount in a sack according to a second embodiment.
FIG. 5 is a flowchart illustrating a control method according to a second embodiment.
FIG. 6 is a diagram showing a relationship between an injector tip temperature and a fuel amount in a sack according to a third embodiment.
FIG. 7 is a flowchart illustrating a control method according to a third embodiment.
FIG. 8 is a cross-sectional view illustrating an injector tip structure.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Direct injection engine 1, 101 ... Intake port, 102 ... Air cleaner, 103 ... Intake pipe, 104 ... Throttle valve, 105 ... Surge tank, 106 ... Intake manifold, 110 ... Combustion chamber, 111 ... Piston, 112 ... Arm, 113 rank shaft, 114 rotating plate, 115 spark plug, 116 intake valve, 117 exhaust valve, 120 cylinder head, 121 camshaft, 122 ignition coil, 123 injector, 130 exhaust manifold, 131 ... three-way catalyst, 132 ... exhaust pipe, 200 ... ECU, 201 ... aeroflow sensor, 202 ... throttle position sensor, 203 ... throttle motor, 204 ... surge tank pressure sensor, 205 ... injector tip temperature sensor, 206 ... cam position sensor , 207 ... Rank position sensor, 1231 ... needle, 1232 ... holder, 1233 ... the injection hole, 1234 ... sack

Claims (14)

An internal combustion engine having an injection valve for injecting fuel into a combustion chamber,
Intake air amount adjusting means for adjusting the amount of air supplied to the combustion chamber,
Control means for controlling the amount of air in the intake air amount adjusting means,
The internal combustion engine according to claim 1, wherein the control means reduces an amount of air supplied to the combustion chamber from a reference amount for a predetermined period after fuel for combustion is injected from the injection valve into the combustion chamber. 2. The internal combustion engine according to claim 1, wherein the control unit sets the period in which the amount of air is reduced to a period in which fuel in the sack at the tip of the direct injection valve is sufficient to be sucked by negative pressure. The internal combustion engine according to claim 1, wherein the control unit increases the amount of air supplied to the combustion chamber from the reference amount for a predetermined period after the period in which the amount of air is reduced. 4. The control device according to claim 3, wherein the control unit sets the period in which the amount of air is increased to a period in which the amount of air that has become smaller than the required amount of intake air by reducing the amount of air can be compensated. 5. Internal combustion engine. Further provided is a crank angle detecting means for detecting an angle of the crankshaft,
The internal combustion engine according to any one of claims 1 to 4, wherein the control unit controls the intake air amount adjusting unit based on a rotation angle of the crankshaft detected by the crank angle detecting unit. An internal combustion engine having an injection valve for injecting fuel into a combustion chamber,
Fuel amount adjusting means for adjusting the amount of fuel supplied to the combustion chamber via the injection valve;
Control means for controlling the fuel amount in the fuel amount adjustment means,
The internal combustion engine, wherein the control means supplies a very small amount of fuel to the injection valve after fuel for combustion is injected from the injection valve into the combustion chamber. Injection valve temperature detection means for detecting the temperature of the tip of the injection valve is further provided,
7. The internal combustion engine according to claim 6, wherein the control unit causes the small amount of fuel to be supplied when the temperature of the tip of the injection valve detected by the injection valve temperature detection unit is equal to or higher than a predetermined temperature. Further provided is a crank angle detecting means for detecting an angle of the crankshaft,
8. The internal combustion engine according to claim 6, wherein the control unit causes the small amount of fuel to be supplied when the rotation angle of the crankshaft detected by the crank angle detection unit reaches a predetermined angle. 9. An internal combustion engine having an injection valve for injecting fuel into a combustion chamber,
Fuel amount adjusting means for adjusting the amount of fuel supplied to the combustion chamber via the injection valve;
Control means for controlling the fuel amount in the fuel amount adjusting means,
Injection valve temperature detection means for detecting the temperature of the injection valve tip,
The control unit is configured to supply the combustion fuel supplied from the injection valve into the combustion chamber in a plurality of times, and the temperature of the injection valve tip detected by the injection valve temperature detection unit is a predetermined temperature. An internal combustion engine characterized in that the second and subsequent fuels are supplied when the internal combustion engine becomes full. Further provided is a crank angle detecting means for detecting an angle of the crankshaft,
10. The internal combustion engine according to claim 9, wherein the control means causes the second and subsequent fuel to be supplied when the rotation angle of the crankshaft detected by the crank angle detection means has reached a predetermined angle. A control method for an internal combustion engine including an injection valve for injecting fuel into a combustion chamber,
Injecting combustion fuel from the injector into the combustion chamber;
Reducing the amount of air supplied into the combustion chamber from a reference amount for a predetermined period from the supply of the combustion fuel. The control method for an internal combustion engine according to claim 11, further comprising a step of increasing the amount of air supplied to the combustion chamber from the reference amount for a predetermined period after the step of reducing the amount of air. A control method for an internal combustion engine including an injection valve for injecting fuel into a combustion chamber,
Injecting combustion fuel from the injector into the combustion chamber;
Supplying a very small amount of fuel to the injection valve after a predetermined period from the injection of combustion fuel into the combustion chamber from the injection valve. A control method for an internal combustion engine including an injection valve for injecting fuel into a combustion chamber,
Supplying a first combustion fuel to the combustion chamber via an injection valve;
Supplying the second and subsequent combustion fuel when the temperature at the tip of the injection valve reaches a predetermined temperature.

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