JP4148156B2 - Fuel injection control device for internal combustion engine - Google Patents

Description

  The present invention relates to a fuel injection control device for an internal combustion engine.

  Fuel is supplied to the fuel injection valve of the internal combustion engine at a relatively high pressure so that the fuel can be injected. In particular, when the fuel is directly injected into the combustion chamber from the fuel injection valve as in the internal combustion engine described in Patent Document 1, the fuel is injected at the timing when the pressure in the combustion chamber is very high. Since the fuel must be injected from the valve, fuel is supplied to the fuel injection valve at a very high pressure.

Japanese Patent Laid-Open No. 7-103097 JP-A-9-42109 JP-A-8-28382

  By the way, as described above, fuel is supplied to the fuel injection valve at a high pressure. Here, even after the operation of the internal combustion engine is stopped, if the fuel pressure in the fuel injection valve is high, fuel leaks from the fuel injection valve while the engine operation is stopped. If fuel leaks from the fuel injection valve while the engine is stopped, then when the internal combustion engine is started next time, more fuel than necessary is present in the combustion chamber. In such a case, when the internal combustion engine is started, fuel may self-ignite or knock in the combustion chamber.

  Therefore, for example, in Patent Document 1, when the ignition switch is turned off to stop the operation of the internal combustion engine, the fuel pressure in the fuel distribution pipe becomes lower than the set pressure (that is, in the fuel injection valve). The fuel pressure of the engine becomes lower than the set pressure), so that the operation of the internal combustion engine is continued. That is, by continuing fuel injection from the fuel injection valve until the fuel pressure in the fuel distribution pipe becomes lower than the set pressure, the fuel pressure in the fuel distribution pipe is reduced and the injected fuel is combusted in the combustion chamber. By doing so, the next time the internal combustion engine is started, no fuel remains in the combustion chamber.

  Thus, in the field of internal combustion engines, there is a demand for suppressing leakage of fuel from the fuel injection valve while the engine is stopped. Accordingly, an object of the present invention is to suppress the leakage of fuel from the fuel injection valve while the engine is stopped by a method different from the conventional method.

In order to solve the above-mentioned problem, in the first invention, in an internal combustion engine having a fuel injection valve for directly injecting fuel into a combustion chamber, the exhaust valve is disposed after the engine operation is stopped. Fuel is injected from the fuel injection valve.
In order to solve the above-described problem, in a second invention, in an internal combustion engine having a fuel injection valve for injecting fuel into an intake port, a cylinder in which an intake valve and an exhaust valve are opened after the engine operation is stopped is provided. Fuel is injected from a fuel injection valve arranged in the corresponding intake port.

In the third invention, in the first or second invention, the fuel injection after the engine operation is stopped is performed until the fuel pressure in the fuel injection valve becomes lower than a predetermined pressure.
In a fourth aspect, in the third aspect, the predetermined pressure is at least higher than the vapor pressure of the fuel.
In the fifth invention, in the first or second invention, the fuel injection after the engine operation is stopped is performed until the fuel pressure in the fuel injection valve becomes lower than the predetermined first pressure, and then the engine operation is performed. When the fuel pressure in the fuel injection valve becomes higher than a predetermined second pressure higher than the first pressure during the stop, the fuel is increased until the fuel pressure in the fuel injection valve becomes lower than the first pressure. Injection is performed.
According to a sixth aspect, in the fifth aspect, the first pressure is higher than at least the vapor pressure of the fuel.

In the seventh aspect, in the first or second aspect, the fuel injection after the engine operation is stopped is performed for a predetermined time from when the engine operation is stopped.
In the eighth aspect, in the first or second aspect, the fuel injection after the engine operation is stopped is performed a predetermined number of times at a predetermined time interval.
In the ninth invention, in the first or second invention, a catalyst having a function of oxidizing fuel is arranged in the exhaust passage.

  According to the first aspect of the invention, fuel injection is performed after the engine operation is stopped, and the fuel pressure in the fuel injection valve is lowered, so that leakage of fuel from the fuel injection valve during engine operation stop is suppressed. In addition, since the exhaust valve is opened in the cylinder in which fuel injection is performed after the engine operation is stopped, the fuel injected from the fuel injection valve into the combustion chamber after the engine operation is stopped is passed through the exhaust port by natural convection. It is discharged out of the combustion chamber. Therefore, when the internal combustion engine is started next time, it is possible to suppress the existence of unnecessary fuel in the combustion chamber.

  According to the second aspect of the invention, fuel injection is performed after the engine operation is stopped, and the fuel pressure in the fuel injection valve is lowered, so that leakage of fuel from the fuel injection valve during engine operation stop is suppressed. In addition, in the cylinder where fuel injection is performed after the engine operation is stopped, the intake valve and the exhaust valve are opened. Therefore, the fuel injected from the fuel injection valve to the intake port after the engine operation is stopped is combusted by natural convection. It is discharged out of the combustion chamber through the chamber and the exhaust port. Therefore, when the internal combustion engine is started next time, it is possible to suppress the intake of unnecessary fuel into the combustion chamber.

  Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments. FIG. 1 shows a spark ignition type internal combustion engine (so-called gasoline engine). In the following, the present invention will be described using a spark ignition type internal combustion engine as an example, but the present invention may be applied to a compression ignition type internal combustion engine (so-called diesel engine).

  In FIG. 1, 1 is a main body of an internal combustion engine, 1a is a combustion chamber (in the example shown in FIG. 1, there are four combustion chambers, hereinafter these combustion chambers are also referred to as “cylinders”), 2 is an intake branch pipe, Is a surge tank, 4 is an intake duct, 5 is an air cleaner, 6 is a step motor, 7 is a throttle valve, 8 is an exhaust manifold, and 9 is a catalytic converter. In the catalytic converter 9, a three-way catalyst capable of simultaneously purifying hydrocarbons (fuel), carbon monoxide, and nitrogen oxides with a high purification rate is disposed. That is, the three-way catalyst has an oxidizing ability to oxidize hydrocarbon (fuel) and carbon monoxide and a reducing ability w to reduce nitrogen oxides. Further, the operation of the step motor 6, that is, the operation of the throttle valve 7 is controlled by an electronic control unit 30 described later.

  A spark plug 1b is provided corresponding to each cylinder 1a. A fuel injection valve 11 is provided corresponding to each cylinder 1a. The fuel injection valve 11 is provided so as to directly inject fuel into the corresponding cylinder 1a. Therefore, the illustrated internal combustion engine is a so-called direct injection type spark ignition internal combustion engine. The operation of the spark plug 1b and the fuel injection valve 11 is controlled by an electronic control unit 30 described later.

  The fuel tank 12 is connected to a low pressure pump 14 via a fuel filter 13. The low pressure pump 14 is connected to the high pressure pump 16 via the fuel pressure regulator 15. The fuel pressure regulator 15 functions to return a part of the fuel discharged from the low pressure pump 14 to the fuel tank 12 when the pressure of the fuel supplied to the high pressure pump 16 becomes higher than a predetermined pressure. According to this, the pressure of the fuel supplied to the high pressure pump 16 is kept constant.

  The high-pressure pump 16 is a pump that is driven by driving the output of the internal combustion engine, and is connected to the fuel distribution pipe 17 via a check valve 18. The check valve 18 functions to allow only the flow of fuel in the direction from the high-pressure pump 16 toward the fuel distribution pipe 17. The fuel distribution pipe 17 is connected to the fuel injection valve 11. The fuel discharge side of the high-pressure pump 16 is connected to the fuel suction side of the high-pressure pump 16 via an electromagnetic valve 19. The larger the opening of the solenoid valve 19, the larger the amount of fuel recirculated from the fuel discharge side of the high pressure pump 16 to the fuel suction side, and therefore the amount of fuel supplied from the high pressure pump 16 to the fuel distribution pipe 17. Less. When the opening degree of the solenoid valve 19 is fully opened, the amount of fuel supplied from the high pressure pump 16 to the fuel distribution pipe 17 becomes zero. The operation of the electromagnetic valve 19 is controlled by an electronic control device 30 described later.

  The electronic control unit 30 is composed of a digital computer and includes a ROM (Read Only Memory) 32, a RAM (Random Access Memory) 33, a CPU (Microprocessor) 34, and an input port 35 which are connected to each other via a bidirectional bus 31. And an output port 36. A fuel pressure sensor 21 that generates an output voltage proportional to the fuel pressure in the fuel distribution pipe 17 (hereinafter also referred to as “in-pipe fuel pressure”) is attached to the fuel distribution pipe 17. The output voltage of the fuel pressure sensor 21 is input to the input port 35 via the AD converter 37. Based on the output voltage of the fuel pressure sensor 21, the fuel pressure in the fuel distribution pipe 17 is calculated.

  The accelerator pedal 10 is connected to a load sensor 25 that generates an output voltage proportional to the amount of depression of the accelerator pedal 10. The output voltage of the load sensor 25 is input to the input port 35 via the AD converter 37. Based on the output voltage of the load sensor 21, a load required for the internal combustion engine is calculated. The input port 35 is connected to a crank angle sensor 26 that generates an output pulse every time the crankshaft rotates, for example, 30 °. Based on the output pulse of the crank angle sensor 26, the crank angle is calculated.

  FIG. 2 is a cross-sectional view of the main body 1 of the internal combustion engine shown in FIG. Also in FIG. 2, 1a represents a combustion chamber, 1b represents a spark plug, 2 represents an intake branch pipe, 8 represents an exhaust manifold, and 11 represents a fuel injection valve. In FIG. 2, 40 is a cylinder head, 41 is a cylinder block, 42 is a piston, 43 is an intake valve, 44 is an intake port, 45 is an exhaust valve, and 46 is an exhaust port.

  By the way, in each cylinder 1a, an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke are sequentially performed. As described above, the internal combustion engine of the present embodiment has four combustion chambers (cylinders) 1a, and each cylinder 1a is designated as the first cylinder, the second cylinder, the third cylinder, the fourth cylinder from the top in FIG. The exhaust stroke of each cylinder 1a is performed in the order of the first cylinder, the third cylinder, the fourth cylinder, and the second cylinder while shifting by 180 ° in crank angle. FIG. 3 shows the state of execution of the exhaust stroke in each cylinder 1a.

  That is, in FIG. 3, # 1 indicates the exhaust stroke of the first cylinder, # 2 indicates the exhaust stroke of the second cylinder, # 3 indicates the exhaust stroke of the third cylinder, and # 4 indicates the exhaust stroke of the fourth cylinder. The stroke is shown, and CA is the crank angle. As can be seen from FIG. 3, in this embodiment, the exhaust stroke of the first cylinder is performed at a crank angle of 540 ° to 720 °, and the third is performed at a crank angle of 0 ° (720 °) to 180 °. The exhaust stroke of the cylinder is performed, the exhaust stroke of the fourth cylinder is performed at a crank angle of 180 ° to 360 °, and the exhaust stroke of the second cylinder is performed at a crank angle of 360 ° to 540 °.

  Next, fuel injection control after engine operation stop according to the first embodiment will be described. When the engine operation is stopped, the solenoid valve 19 is fully opened and the operation of the high-pressure pump 16 is also stopped, so that the fuel pressure in the fuel distribution pipe 17 no longer rises. However, if the fuel injection is also stopped when the engine operation is stopped, the high-pressure fuel remains accumulated in the fuel distribution pipe 17 during the engine operation stop. In this case, fuel may leak from the fuel injection valve 11 while the engine operation is stopped. Then, when the engine operation is started next, excess fuel exists in the combustion chamber 1a, which may cause self-ignition and knocking.

  In order to prevent fuel from leaking from the fuel injection valve 11 while the engine is stopped, fuel injection may be performed simultaneously with or after the engine operation is stopped. According to this, since the operation of the high-pressure pump 16 is stopped, the supply of fuel to the fuel distribution pipe 17 is stopped and the fuel is injected from the fuel injection valve 11. As a result, the fuel pressure in the fuel distribution pipe 17 is lowered.

  However, if the intake valve 43 and the exhaust valve 45 are both closed in the cylinder in which the fuel is injected, after all, excess fuel (that is, in the combustion chamber 1a when the engine operation is started next) There will be more fuel) than the amount of fuel required to generate the target torque. Further, if only the intake valve 43 is opened in the cylinder in which the fuel is injected, the fuel flows out to the intake port 44 and the intake branch pipe 2 by natural convection, and thus flows out to the intake port 4 and the intake branch pipe 2. Since the fuel is sucked into the combustion chamber 1a together with the air sucked into the combustion chamber 1a, also in this case, excess fuel exists in the combustion chamber 1a when the engine operation is started next time.

  Therefore, in the present embodiment, leakage of fuel from the fuel injection valve 11 during engine stop is suppressed as follows. That is, first, from the crank angle when the engine operation is stopped, which cylinder is in the exhaust stroke state (that is, which cylinder has stopped the engine operation during the exhaust stroke). judge. For example, if the engine operation is stopped at a crank angle of 630 °, it is determined that the first cylinder is in an exhaust stroke state. When it is determined that the first cylinder is in the exhaust stroke state, fuel injection is performed in the first cylinder. According to this, since the fuel pressure in the fuel distribution pipe 17 is reduced, fuel leakage from the fuel injection valve 11 during engine operation stop is suppressed.

  In addition, since the cylinder in which the fuel is injected after the engine operation is stopped is in the exhaust stroke state, the exhaust valve is opened. Therefore, the fuel injected into the cylinder at this time flows out to the exhaust port by natural convection while the engine operation is stopped. For this reason, when the engine operation is started next time, there is no excess fuel in the cylinder, so that self-ignition and knocking hardly occur.

  Further, as described above, the fuel that has flowed out to the exhaust port by natural convection eventually reaches the three-way catalyst via the exhaust manifold. The fuel is purified by the oxidation action of the three-way catalyst. Therefore, in order to purify the fuel satisfactorily with the three-way catalyst, it is preferable that the temperature of the three-way catalyst is equal to or higher than the activation temperature. Therefore, when fuel injection is performed after the engine operation is stopped, as soon as possible after the engine operation is stopped. It is preferable to perform fuel injection at the timing.

  Further, the fuel injection performed after the engine operation is stopped according to the first embodiment is performed until the fuel pressure in the fuel distribution pipe 17 (in-pipe fuel pressure) decreases to a predetermined pressure (hereinafter also referred to as “predetermined pressure”). Is called. Further, while the engine fuel is stopped, the lower the fuel pressure in the pipe, the more reliably the fuel leakage from the fuel injection valve 11 can be suppressed. However, if the fuel pressure in the pipe is too low, the fuel in the fuel distribution pipe 17 is reduced. Evaporates into a gas, and so-called vapor may be generated. In this case, when the engine operation is started next time, a predetermined amount of fuel is not supplied to the fuel injection valve 11. Therefore, when fuel injection is performed after the engine is stopped, the in-pipe fuel pressure (that is, the predetermined pressure described above) is low enough to prevent fuel from leaking from the fuel injection valve 11 while the engine is stopped. The value is set so high that vapor does not occur in the fuel distribution pipe 17. Therefore, in other words, when fuel injection is performed after engine shutdown, the target pipe fuel pressure is set to a value that is higher than the fuel vapor pressure but very close to the fuel vapor pressure. The

  FIG. 4 shows the fuel pressure in the fuel distribution pipe (P in FIG. 4) and the predetermined fuel injection valve (that is, during the exhaust stroke when the engine operation is stopped) when the fuel injection control after the engine operation stop is performed according to the first embodiment. FIG. 4 shows a control signal (S in FIG. 4) to a fuel injection valve provided in the cylinder 1a. As shown in FIG. 4, after the engine operation is stopped, a signal (ON signal) for opening the predetermined fuel injection valve 11 is issued at time t0, and fuel injection is performed in the predetermined cylinder. As a result, the fuel pressure (in-pipe fuel pressure) P in the fuel distribution pipe 17 is reduced to a predetermined pressure Pth at once. When the in-pipe fuel pressure P reaches the predetermined pressure Pth, the transmission of the ON signal is stopped and the fuel injection is stopped.

  FIG. 5 shows an example of a flowchart for executing the fuel injection control after the engine operation is stopped according to the first embodiment. The routine of FIG. 5 is started when the engine operation is stopped. When the routine of FIG. 5 is disclosed, first, at step 10, the crank angle is read. Next, in step 11, it is determined which cylinder is the predetermined cylinder (that is, the cylinder in the exhaust stroke state at this time) based on the crank angle. Next, in step 12, fuel injection is performed in a predetermined cylinder.

  Next, at step 13, it is determined whether or not the fuel pressure P in the fuel distribution pipe 17 has become equal to or lower than a predetermined pressure Pth (P ≦ Pth). Here, when it is determined that P> Pth, the routine repeats step 13. On the other hand, when it is determined that P ≦ Pth, the routine proceeds to step 14. That is, in step 13, step 13 is repeated until it is determined that P ≦ Pth.

  In step 14, the fuel injection in the predetermined cylinder is terminated. That is, fuel injection in the predetermined cylinder is continued until it is determined in step 13 that P ≦ Pth.

  In the first embodiment, the fuel pressure in the fuel distribution pipe 17 (in-pipe fuel pressure) is monitored during fuel injection after the engine operation is stopped, and this fuel pressure has reached a predetermined pressure. When the fuel injection is stopped. However, for example, during the fuel injection after the engine operation is stopped, the fuel injection may be performed for a predetermined time after the engine operation is stopped without monitoring the fuel pressure in the pipe. In this case, it is determined in advance by experiment or the like how long the fuel injection is performed after the engine operation is stopped to reduce the in-pipe fuel pressure to the above-mentioned predetermined pressure. It is preferable to perform fuel injection after the operation is stopped.

  Next, fuel injection control after engine operation stop according to the second embodiment will be described. Even if the fuel injection is performed after the engine operation is stopped to reduce the fuel pressure in the fuel distribution pipe 17 (in-pipe fuel pressure) to a predetermined pressure, the temperature of the fuel system including the fuel distribution pipe 17 is relatively high. When it is high, the fuel pressure in the pipe tends to increase, and this causes fuel leakage from the fuel injection valve 11 during the engine stoppage.

  Therefore, in the second embodiment, fuel injection is performed after the engine operation is stopped as follows. That is, in the second embodiment, as in the first embodiment, when the engine operation is stopped, it is determined which cylinder is a predetermined cylinder (a cylinder in an exhaust stroke state). Then, fuel injection is performed in a predetermined cylinder until the fuel pressure in the fuel distribution pipe 17 (in-pipe fuel pressure) decreases to a predetermined pressure. Thereafter, the in-pipe fuel pressure is monitored, and the in-pipe fuel pressure is higher than the predetermined pressure (hereinafter, the predetermined pressure is referred to as “first predetermined pressure”, which is higher than the first predetermined pressure). When the pressure reaches the “second predetermined pressure”), fuel injection is performed again in the predetermined cylinder until the in-pipe fuel pressure is reduced to the first predetermined pressure. According to this, fuel leakage from the fuel injection valve 11 can be more reliably suppressed even when the engine operation is stopped.

  FIG. 6 is a diagram similar to FIG. 4, and the in-pipe fuel pressure (P in FIG. 6) and the predetermined fuel injection valve (that is, the fuel injection control after engine operation stop in the second embodiment) are performed. 6 shows a control signal (S in FIG. 6) to a fuel injection valve provided in a cylinder in the exhaust stroke when the engine operation is stopped.

  As shown in FIG. 6, in the second embodiment, after the engine operation is stopped, a signal (ON signal) for opening the predetermined fuel injection valve 11 is issued at time t0, and the predetermined cylinder 1a is opened. The fuel injection is started at. When the in-pipe fuel pressure P decreases to the first predetermined pressure Pth1, the transmission of the ON signal is stopped and the fuel injection is terminated. Thereafter, when the in-pipe fuel pressure P gradually increases and reaches the second predetermined pressure Pth2, an ON signal is issued again, and fuel injection is started in the predetermined cylinder 1a. When the in-pipe fuel pressure P decreases to the first predetermined pressure Pth1, the transmission of the ON signal is stopped and the fuel injection is terminated. Thereafter, such fuel injection is repeated.

  FIG. 7 shows an example of a flowchart for executing the fuel injection control after the engine operation is stopped according to the second embodiment. The routine in FIG. 7 is executed every time engine operation is stopped. In the routine of FIG. 7, first, at step 20, the crank angle is read. Next, in step 21, it is determined based on the crank angle which cylinder is the predetermined cylinder, that is, which cylinder is where the engine operation has stopped during the exhaust stroke.

  Next, at step 22, it is determined whether or not the fuel pressure (in-pipe fuel pressure) P in the fuel distribution pipe 17 is equal to or higher than a second predetermined pressure Pth2 (P ≧ Pth2). Here, when it is determined that P ≧ Pth (when step 22 is executed for the first time after the engine operation is stopped, it is determined that P ≧ Pth), the routine proceeds to step 23.

  In step 23, fuel injection is started in a predetermined cylinder. Next, at step 24, it is judged if the in-pipe fuel pressure P is equal to or lower than a first predetermined pressure Pth1 (P ≦ Pth1). Here, when it is determined that P ≦ Pth1, the routine proceeds to step 25, but when it is determined that P> Pth1, the routine returns to step 24. That is, step 24 is repeatedly executed until it is determined that the in-pipe fuel pressure P is equal to or lower than the first predetermined pressure Pth1.

  In step 25, the fuel injection in the predetermined cylinder is terminated. Next, at step 26, the counter N is counted up (N ← N + 1). Here, the counter N indicates the number of fuel injections performed in a predetermined cylinder after the engine operation is stopped. Next, at step 27, it is determined whether or not the counter N has become equal to the predetermined value Nth (N = Nth), that is, whether or not fuel injection has been performed a predetermined number of times in the predetermined cylinder after the engine operation has been stopped. If it is determined that N ≠ Nth, the routine returns to step 22. In this case, step 22 is repeated until it is determined in step 22 that P ≧ Pth2 (that is, until the in-pipe fuel pressure P reaches the second predetermined pressure Pth2). If it is determined in step 22 that P ≧ Pth2, fuel injection is started in a predetermined cylinder in step 23. In step 24, the fuel injection is continued until it is determined that the in-pipe fuel pressure P is equal to or lower than the first predetermined pressure Pth1. If it is determined in step 24 that P ≦ Pth1, the fuel injection is terminated in step 25, and the counter N is counted up in step 26.

  If it is determined in step 27 that N = Nth, the routine proceeds to step 28. In step 28, the counter N is cleared (N ← 0).

  In the above description, the present invention has been described by taking as an example an embodiment in which fuel injection is performed a predetermined number of times in a predetermined cylinder after the engine operation is stopped. For example, the in-pipe fuel pressure is set to the first predetermined pressure after the engine operation is stopped. As long as it reaches, fuel injection may be performed in a predetermined cylinder. In the above description, the present invention has been described by way of an embodiment in which each fuel injection is continued as long as the in-pipe fuel pressure is equal to or higher than the first predetermined pressure. However, for example, the in-pipe fuel pressure is set to be equal to or lower than the first predetermined pressure. It is also possible to obtain in advance a fuel injection time for each fuel injection by an experiment or the like for each fuel injection, and to perform the fuel injection each time for the obtained time.

  In the above description, the present invention has been described by way of an example in which fuel injection is performed in a predetermined cylinder when the in-pipe fuel pressure becomes equal to or higher than the second predetermined pressure after the engine operation is stopped. Fuel injection may be performed in a predetermined cylinder at a predetermined time interval. FIG. 8 is a diagram similar to FIG. 4 and shows an example in which fuel injection is performed in a predetermined cylinder at a predetermined time interval after engine operation is stopped. In the example shown in FIG. 8, after the engine operation is stopped, a signal (ON signal) for opening the predetermined fuel injection valve 11 is issued at time t0, and fuel injection is started in the predetermined cylinder. And when predetermined time passes, transmission of an ON signal is stopped and fuel injection is complete | finished. Thereafter, when a predetermined time (T in FIG. 8) further elapses, an ON signal is issued, and fuel injection is started again in the predetermined cylinder. Thereafter, such fuel injection is repeated.

  In the above description, the present invention has been described by taking an example of an internal combustion engine that directly injects fuel into a combustion chamber. However, the present invention can also be applied to an internal combustion engine that injects fuel into an intake port. However, in this case, the cylinder in which the intake valve and the exhaust valve are open needs to be a predetermined cylinder. That is, when the present invention is applied to an internal combustion engine that injects fuel into an intake port (hereinafter referred to as a “port injection internal combustion engine”), fuel injection is performed after the engine operation is stopped. In order to allow the fuel to reach the three-way catalyst by natural convection, it is necessary to pass through the combustion chamber. For this purpose, the fuel is introduced into the intake port corresponding to the cylinder in which the intake valve and the exhaust valve are open. A jet should be made. For this reason, when the present invention is applied to a port injection type internal combustion engine, a cylinder in which an intake valve and an exhaust valve are opened is set as a predetermined cylinder. Although the intake stroke is performed after the exhaust stroke, when these strokes are performed only at 180 ° in crank angle, there is no timing when the intake valve and the exhaust valve are opened. Actually, there is a timing when the intake valve and the exhaust valve are opened (so-called valve overlap) when the exhaust stroke is changed to the intake stroke. Therefore, when the present invention is applied to a port injection type internal combustion engine, fuel injection is performed at an intake port corresponding to a cylinder at a timing when the intake valve and the exhaust valve are opened. However, the timing at which the intake valve and the exhaust valve are opened is very short, and there are often no cylinders in which the intake valve and the exhaust valve are open when the engine is stopped. When the present invention is applied to an engine, it is preferable to provide a mechanism that forces any one of the cylinders to open the intake valve and the exhaust valve.

1 is an overall view of a spark ignition type internal combustion engine to which the present invention is applied. It is sectional drawing of the main body of the internal combustion engine shown in FIG. It is a figure which shows the execution order of the exhaust stroke in each cylinder. It is a figure which shows in-pipe fuel pressure P and the control signal S to a fuel injection valve when fuel injection is performed after engine operation stop according to 1st Embodiment. It is a figure which shows an example of the flowchart which performs the fuel-injection control after engine operation stop according to 1st Embodiment. It is a figure which shows the fuel pressure P in a pipe | tube and the control signal S to a fuel injection valve when fuel injection is performed after engine operation stop according to 2nd Embodiment. It is a figure which shows an example of the flowchart which performs the fuel-injection control after engine operation stop according to 2nd Embodiment. It is a figure which shows the fuel signal P in a pipe | tube and the control signal S to a fuel injection valve when fuel injection is performed after engine operation stop according to another embodiment.

Explanation of symbols

1 ... Engine body 1a ... Combustion chamber (cylinder)
DESCRIPTION OF SYMBOLS 1b ... Spark plug 2 ... Intake branch pipe 8 ... Exhaust manifold 9 ... Catalytic converter 16 ... High pressure pump 17 ... Fuel distribution pipe 21 ... Fuel pressure sensor 43 ... Intake valve 44 ... Intake port 45 ... Exhaust valve 46 ... Exhaust port

Claims (9)

  An internal combustion engine having a fuel injection valve for directly injecting fuel into a combustion chamber, wherein the fuel is injected from a fuel injection valve disposed in a cylinder in which an exhaust valve is opened after the operation of the engine is stopped Injection control device.   In an internal combustion engine having a fuel injection valve that injects fuel into the intake port, fuel is supplied from the fuel injection valve disposed in the intake port corresponding to the cylinder in which the intake valve and the exhaust valve are opened after the engine operation is stopped. A fuel injection control device.   3. The fuel injection control device according to claim 1, wherein the fuel injection after the engine operation is stopped is performed until the fuel pressure in the fuel injection valve becomes lower than a predetermined pressure.   The fuel injection control device according to claim 3, wherein the predetermined pressure is higher than at least the vapor pressure of the fuel.   The fuel injection after the engine operation is stopped is performed until the fuel pressure in the fuel injection valve becomes lower than a predetermined first pressure. Thereafter, the fuel pressure in the fuel injection valve is changed to the first pressure during the engine operation stop. 3. The fuel injection is performed until the fuel pressure in the fuel injection valve becomes lower than the first pressure when the pressure becomes higher than a predetermined second pressure higher than the first pressure. A fuel injection control device according to claim 1.   6. The fuel injection control device according to claim 5, wherein the first pressure is higher than at least the vapor pressure of the fuel.   3. The fuel injection control device according to claim 1, wherein the fuel injection after the engine operation is stopped is performed for a predetermined time from the time when the engine operation is stopped.   3. The fuel injection control device according to claim 1, wherein the fuel injection after the engine operation is stopped is performed a predetermined number of times at a predetermined time interval.   The fuel injection control device according to claim 1 or 2, wherein a catalyst having a function of oxidizing fuel is disposed in the exhaust passage.

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