JPH0932617A - Spark ignition internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent deterioration of operation efficiency of an engine when abnormality occurs in the high pressure fuel supply system by providing a bypass passage, a valve mechanism, an abnormality diagnosing means and a bypass control means, and bypassing fuel through a high pressure fuel pump to be supplied to a fuel injection valve. SOLUTION: A control unit 3 has functions as an abnormality diagnosing means, a pulse width correcting means and a bypass control means. If the condition where fuel pressure detected by a fuel pressure sensor 21 is outside of tolerance continues more than designated time, a solenoid valve 13 is controlled to be opened, and the injection pulse width is increased and corrected to cope with the condition where a bypass passage 12 is opened and fuel is supplied to a fuel injection valve 2 by supply pressure of a low pressure fuel pump 9. Thus, the fuel supply pressure to the fuel injection valve 2 is stabilized to the supply pressure produced by the low pressure fuel pump 9 and a low pressure regulator 11, and a required quantity of fuel can be stably injected and supplied to an engine.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spark ignition type internal combustion engine, and more particularly to a spark ignition type internal combustion engine in which a low pressure fuel pump and a high pressure fuel pump are provided in series to supply fuel.

[0002]

2. Description of the Related Art Conventionally, as a spark ignition type internal combustion engine having a structure in which a low pressure fuel pump and a high pressure fuel pump are provided in series to supply fuel, there is one disclosed in JP-A-4-339152. It was This is a high-pressure fuel pump for supplying high-pressure fuel to a fuel injection valve for directly injecting fuel into a combustion chamber, and a low-pressure fuel pump for supplying fuel in a fuel tank to the high-pressure fuel pump. It is configured with.

Here, the high-pressure fuel pump is engine-driven via a belt, while the low-pressure fuel pump is motor-driven. Further, JP-A-2-146239 discloses a spark ignition type engine in which the high-pressure fuel pump is driven by a motor.

[0004]

By the way, as described above, in the system for supplying fuel by arranging the low-pressure fuel pump and the high-pressure fuel pump in series, the discharge amount of the high-pressure fuel pump is abnormal and the high-pressure regulator is When an abnormality such as an open or close failure occurs in the high-pressure fuel supply system, the fuel pressure supplied to the fuel injection valve becomes abnormal, so the amount of fuel actually injected from the fuel injection valve corresponds to the injection pulse width. There is a fear that the air-fuel ratio will change and the drivability of the engine will deteriorate. In particular, if an abnormality such that the fuel supply pressure fluctuates greatly occurs, the air-fuel ratio may fluctuate greatly, which may significantly impair the operational stability of the engine.

The present invention has been made in view of the above problems, and in a system for supplying fuel by arranging a low-pressure fuel pump and a high-pressure fuel pump in series, particularly when an abnormality occurs in the high-pressure fuel supply system, operation of the engine is performed. The purpose is to be able to avoid a significant deterioration in sex.

[0006]

Therefore, a spark ignition type internal combustion engine according to the invention of claim 1 comprises a high pressure fuel pump for supplying fuel to a fuel injection valve, and a low pressure fuel pump for supplying fuel to the high pressure fuel pump. It is a spark ignition type internal combustion engine having a configuration as shown in FIG. In FIG.
The bypass passage is a fuel passage that bypasses the high-pressure fuel pump, and the valve mechanism opens and closes the bypass passage.

The abnormality diagnosing means determines whether or not there is an abnormality in the high pressure fuel supply system including the high pressure fuel pump. The bypass control means controls the opening of the valve mechanism when the abnormality diagnosis means determines that an abnormality has occurred. With this configuration, when an abnormality occurs in the high-pressure fuel supply system including the high-pressure fuel pump and it becomes impossible to stably supply the fuel at the desired pressure to the fuel injection valve, the high-pressure fuel pump is bypassed. Then, the fuel is supplied to the fuel injection valve to stabilize the low-pressure injection state by the low-pressure fuel pump.

Further, in the spark ignition type internal combustion engine according to the invention of claim 2, as shown in FIG. 2, in addition to the structure of the invention of claim 1, the bypass control means controls the opening of the valve mechanism. At this time, a pulse width correction means for increasing and correcting the injection pulse width output to the fuel injection valve so as to correspond to the fuel supply pressure by the low pressure fuel pump is provided.

According to this structure, when an abnormality that bypasses the high-pressure fuel pump occurs, the injection pulse width is corrected to be increased, and the fuel injection amount is prevented from decreasing due to the fuel pressure lowering than the desired pressure. In the spark ignition internal combustion engine according to the invention of claim 3, the abnormality diagnosis means includes a fuel pressure detection means for detecting a fuel pressure on the downstream side of the high pressure fuel pump, and the fuel detected by the fuel pressure detection means. The configuration is such that the presence or absence of abnormality is diagnosed based on the pressure.

According to this structure, the fuel pressure on the downstream side of the high-pressure fuel pump is detected to reliably diagnose the abnormality of the fuel pressure. In the spark ignition type internal combustion engine according to the invention of claim 4, the abnormality diagnosis means includes a drive torque detection means for detecting the drive torque of the high-pressure fuel pump, and the drive detected by the drive torque detection means. The configuration is such that the presence or absence of abnormality is diagnosed based on the torque.

According to this structure, the driving torque of the high-pressure fuel pump is detected, and it is possible to cope with an abnormality such as seizure of the high-pressure fuel pump. In the spark ignition type internal combustion engine according to the invention of claim 5, the abnormality diagnosis means includes:
The air-fuel ratio detecting means for detecting the air-fuel ratio of the engine intake air-fuel mixture is included, and the presence or absence of abnormality is diagnosed based on the air-fuel ratio detected by the air-fuel ratio detecting means.

According to this structure, when the fuel supply pressure to the fuel injection valve changes, the amount of fuel actually injected and supplied changes with respect to the injection pulse width to change the air-fuel ratio. Indirect diagnosis of abnormal fuel supply pressure. In the spark ignition internal combustion engine according to the invention of claim 6, in the invention of claim 5, the abnormality diagnosing means is based on an air-fuel ratio detected by the air-fuel ratio detecting means, an injection pulse width and an engine intake air amount. The configuration is such that the presence or absence of an abnormality is diagnosed based on the obtained difference from the indicated air-fuel ratio.

With this configuration, the variation in the injection amount due to the change in the fuel supply pressure is detected with high accuracy based on the difference between the actual air-fuel ratio and the expected air-fuel ratio based on the injection pulse width. In the spark ignition internal combustion engine according to the invention of claim 7, the high-pressure fuel pump is driven by an electric motor, and the abnormality diagnosis means is based on at least one of a drive voltage and a drive current of the electric motor. The configuration is such that the presence or absence of abnormality is diagnosed.

According to this structure, in the structure in which the high-pressure fuel pump is driven by the electric motor, the high-pressure fuel pump is no longer driven at the desired rotation speed due to an abnormality in the drive voltage or drive current of the motor. To diagnose. In the spark ignition internal combustion engine according to the invention of claim 8, the abnormality diagnosis means includes a pump rotation speed detection means for detecting the rotation speed of the high-pressure fuel pump, and the pump rotation speed detection means detects the rotation speed. Based on the rotation speed of the high-pressure fuel pump, the existence of abnormality is diagnosed.

According to this structure, the high-pressure fuel pump is abnormal when the electric motor drives the motor, the driving force transmission mechanism such as the belt and the gear when the engine is driven, and the high-pressure fuel pump itself. The abnormality in the high pressure fuel pump causes an abnormality in the rotation speed of the high pressure fuel pump, and a state in which the discharge amount of the high pressure fuel pump is abnormal is diagnosed. Claim 9
In the spark ignition internal combustion engine according to the invention, the abnormality diagnosing means determines the abnormality occurrence only when the value of the parameter that is the determination target of the abnormality diagnosis is outside the predetermined allowable range for a predetermined time or more. It was configured to do.

According to such a configuration, the abnormality is diagnosed only when the parameter used for the abnormality diagnosis such as the fuel pressure is out of the predetermined permissible range for a predetermined time or more, and the abnormality is instantaneously detected in the normal state. Even if a value is displayed, it is possible to avoid erroneous diagnosis of an abnormality in the high-pressure fuel supply system based on this value. In the spark ignition internal combustion engine according to the invention of claim 10, the high-pressure fuel pump is an engine-driven pump, the driving force is transmitted by a belt, the abnormality diagnosis means, the belt breakage The belt breakage detection means for detecting the occurrence of a failure is included, and when the breakage of the belt is detected by the belt breakage detection means, the occurrence of abnormality is determined.

According to this structure, in the high-pressure fuel pump in which the driving force from the engine is transmitted through the belt, it is possible to cope with the case where the high-pressure fuel pump cannot be driven due to the breakage of the belt. Bypass control will be executed.

[0018]

Embodiments of the present invention will be described below. FIG. 3 is a system configuration diagram of the spark ignition type internal combustion engine of the first embodiment. In FIG. 3, the spark ignition type internal combustion engine 1 is provided with a fuel injection valve 2 facing the combustion chamber of each cylinder. The fuel injection valve 2 may be one that injects and supplies fuel into the intake passage.

The fuel injection valve 2 is controlled to open according to an injection pulse signal (energization control signal) sent from the control unit 3. Fuel is distributed from the common rail 4 through the distribution pipe 5 to the fuel injection valve 2, and the common rail 4 is pressure-fed from a high-pressure fuel pump 6 to a predetermined high pressure by a high-pressure regulator 7. The adjusted fuel is supplied through the fuel passage 8. Therefore, the fuel injection amount from the fuel injection valve 2 is adjusted by the pulse width (injection pulse width) of the injection pulse signal.

On the other hand, the high-pressure fuel pump 6 is supplied with the fuel sucked from the fuel tank 10 by the low-pressure fuel pump 9 after being adjusted to a predetermined low pressure by the low-pressure regulator 11. The regulator 11 adjusts the fuel pressure to a constant pressure by opening the return passage 11a to the fuel tank 9 and returning the fuel when the fuel pressure becomes equal to or higher than a predetermined pressure. When the pressure exceeds the pressure, the return passage 7a is opened to return the fuel to the low pressure fuel pump 9 and the low pressure regulator 11 to adjust the fuel pressure to a constant pressure.

A bypass passage 12 for bypassing the high-pressure fuel pump 6 and supplying fuel to the fuel injection valve 2 is provided.
Is provided in the bypass passage 12
A solenoid valve (valve mechanism) 13 for opening and closing is provided. The solenoid valve 13 is a normally-closed solenoid valve, which is selectively opened and controlled by energization control by the control unit 3.

Upstream and downstream of the high-pressure fuel pump 6,
Also, on the suction side of the low-pressure fuel pump 9, check valves 14a to 14c are also provided, which also serve to prevent fuel loss. The bypass passage 12 is configured to bypass the check valve 14a, the high-pressure fuel pump 6, and the check valve 14b. The high-pressure fuel pump 6 may be an engine-driven pump (for example, a plunger pump) that operates by transmitting a driving force from the engine by a belt or a gear, or may be a motor-driven pump. Hereinafter, the same applies to other embodiments unless otherwise specified. On the other hand, the low-pressure fuel pump 9 is a pump driven by a motor.

A detection signal from a fuel pressure sensor (fuel pressure detection means) 21 for detecting the fuel pressure in the common rail 4 is input to the control unit 3, as shown in the flow chart of FIG. The abnormality diagnosis of the high-pressure fuel supply system is performed based on the detection result of the fuel pressure sensor 21, and a predetermined fail-safe control is executed when the abnormality occurs.

In the first embodiment, the abnormality diagnosis means,
Functions as pulse width correction means and bypass control means
As shown in the flowchart of FIG. 4, the control unit 3 is provided as software, and the same applies to the embodiments described later. The high-pressure fuel supply system includes the high-pressure fuel pump 6, the high-pressure regulator 7, the check valves 14a and 14b shown in FIG. 3, and an accumulator (not shown).

In the flowchart of FIG. 4, in S1, the fuel pressure P detected by the fuel pressure sensor 21 is read. In S2, it is determined whether or not the read fuel pressure P is within a permissible range corresponding to a normal time (a pressure range sandwiched between a preset permissible maximum value Pmax and permissible minimum value Pmin).

If it is out of the allowable range, the process proceeds to S3,
It is determined whether or not the state of being out of the allowable range continues for a predetermined time or more. If the state in which the fuel pressure P is out of the allowable range continues for a predetermined time or more, the process proceeds to S4, the solenoid valve 13 is controlled to be opened, and the bypass passage 12 is operated in S5.
Is opened and fuel is supplied to the fuel injection valve 2 by the supply pressure of the low-pressure fuel pump 9, and the increase correction of the injection pulse width is executed.

The normal injection pulse width is the high pressure fuel pump 6
Since it is calculated to correspond to the high pressure fuel supply by, the injection amount per unit time decreases when the actual fuel supply pressure decreases. Cannot be injected and supplied to the engine 1. In the case of the present embodiment, by opening the bypass passage 12, the fuel pressure is not the desired pressure by the high-pressure regulator 7 but the adjustment pressure by the low-pressure regulator 11 and stabilizes. A correction coefficient corresponding to the ratio to the regulated pressure by the regulator 11 is multiplied by the injection pulse width calculated corresponding to the desired high pressure to increase the injection pulse width. However, it is possible to inject and supply the required fuel amount.

On the other hand, if it is determined in S2 that the fuel pressure P is within the allowable range, or if it is determined in S3 that the state of being outside the allowable range has not continued for a predetermined time or more, S
6, the electromagnetic valve 13 is held in the closed state, and in S7, injection control is performed with a normal injection pulse width corresponding to the high pressure fuel. With this configuration, the bypass passage 12 is opened when the pressure of the fuel supplied to the fuel injection valve 2 is decreased or increased due to an increase in leakage in the high-pressure fuel pump 6, a failure in the accumulator, a failure in the high-pressure regulator, or the like. Thus, the fuel supply pressure to the fuel injection valve 2 can be stabilized to the supply pressure by the low pressure fuel pump 9 and the low pressure regulator 11, and the injection pulse width is increased and corrected to cope with the fuel supply at the low pressure. Even if an abnormality occurs in the high-pressure fuel supply system that cannot supply fuel at the desired high pressure, it is possible to stably inject and supply the required amount of fuel to the engine. You can avoid the deterioration.

FIG. 5 is a system configuration diagram of the second embodiment. 5 differs from FIG. 3 corresponding to the first embodiment in that a drive torque sensor 22 (drive torque detecting means) for detecting the drive torque of the high-pressure fuel pump 6 is provided in place of the fuel pressure sensor 21. Only the points differ. Then, in the second embodiment, as shown in the flowchart of FIG.
Abnormality diagnosis and fail-safe control are executed.

In the flowchart of FIG. 6, in S11, the drive torque T detected by the drive torque sensor 22 is detected.
Read. At S12, the read drive torque T is read.
Is determined to be within the allowable range corresponding to the normal state. If it is outside the allowable range, the process proceeds to S13, and it is determined whether or not the state outside the allowable range continues for a predetermined time or longer.

When the drive torque T is out of the allowable range for a predetermined time or more, the process proceeds to S14, the solenoid valve 13 is controlled to be opened, and the bypass passage 12 is executed in S15.
Is opened and fuel is supplied to the fuel injection valve 2 by the supply pressure of the low-pressure fuel pump 9, and the increase correction of the injection pulse width is executed. On the other hand, if it is determined in S12 that the drive torque T is within the allowable range, or if it is determined in S13 that the state of being outside the allowable range has not continued for a predetermined time or more, the routine proceeds to S16, where the solenoid valve 13 Hold closed,
In S17, the injection control with the normal injection pulse width corresponding to the high pressure fuel is performed.

With this structure, for example, when seizure of the lubricated portion of the high-pressure fuel pump 6 is about to occur, the bypass passage 12 can be opened by predicting the seizure based on the change in the drive torque T. Burn-in can be prevented in advance, and the injection pulse width is corrected when bypassed, so it is possible to supply the required amount of fuel to the engine and avoid deterioration of drivability.

FIG. 7 is a system configuration diagram of the third embodiment. 7 differs from FIG. 3 corresponding to the first embodiment in that instead of the fuel pressure sensor 21, the oxygen concentration in the exhaust gas that is closely related to the air-fuel ratio of the engine intake air-fuel mixture is detected, An air-fuel ratio sensor 23 (air-fuel ratio detecting means) for detecting the air-fuel ratio of the engine intake air-fuel mixture in a wide range is provided in the exhaust passage 24. Further, FIG. 7 shows a rotation speed sensor 25 for detecting the engine rotation speed and an air flow meter 26 for detecting the intake air flow rate Q of the engine.

Then, in the third embodiment, abnormality diagnosis and fail-safe control are executed as shown in the flowchart of FIG. In the flowchart of FIG.
First, in S21, the actual air-fuel ratio of the engine intake air-fuel mixture is detected based on the detection signal from the air-fuel ratio sensor 23. At S22, based on the fuel amount obtained at the desired fuel pressure with the current injection pulse width and the cylinder intake air amount calculated based on the engine speed and the intake air flow rate Q, the indicated air-fuel ratio ( Calculate the air-fuel ratio that is expected to be obtained when the fuel pressure is adjusted to the desired value.

At S23, the absolute value ΔA / F of the difference between the actual air-fuel ratio and the indicated air-fuel ratio is calculated. In S24, it is determined whether or not the air-fuel ratio difference ΔA / F is a predetermined value or more.
If the air-fuel ratio difference ΔA / F is greater than or equal to the predetermined value, the process proceeds to S25 to confirm that the lean or rich change in the air-fuel ratio is not temporary, and the air-fuel ratio difference ΔA / F is greater than or equal to the predetermined value. It is determined whether or not a certain state continues for a predetermined time or longer.

When the air-fuel ratio difference ΔA / F is kept at a predetermined value or more for a predetermined time or more, the discharge amount of the high-pressure fuel pump 6 is lowered or the high-pressure fuel supply system such as the high-pressure regulator 7 is abnormal. It is determined that the expected fuel amount corresponding to the injection pulse width is not actually injected from the fuel injection valve 2. And in this case, S26
In step S27, the solenoid valve 13 is controlled to be opened, and in S27, the injection pulse width is corrected to increase so as to correspond to the low pressure injection in the state where the bypass passage 12 is opened. So that the fuel needed for the injection is supplied.

On the other hand, when it is determined in S24 that the air-fuel ratio difference ΔA / F is less than the predetermined value, or in S25, the air-fuel ratio difference ΔA / F.
When it is determined that / F is not less than the predetermined value for a predetermined time or more, it is determined that there is no particular abnormality in the high pressure fuel supply system, the solenoid valve 13 is kept closed in S28, and S29 is set. Then, the injection control is executed with the injection pulse width calculated corresponding to the desired high-pressure fuel supply state.

With this configuration, even if the fuel pressure becomes abnormal due to a failure of the high-pressure fuel pump 6 or the high-pressure regulator 7, the supply pressure by the low-pressure fuel pump 9 can be stabilized by the bypass control and the target air-fuel ratio can be obtained. It becomes possible to inject and supply a considerable amount of fuel. Incidentally, when so-called air-fuel ratio feedback control is performed to correct the injection pulse width so that the actual air-fuel ratio approaches the target air-fuel ratio based on the detection result of the air-fuel ratio sensor 23, the correction value of the injection pulse width is set. Based on the detection of the deviation of the base air-fuel ratio,
When the base air-fuel ratio deviates by more than a predetermined value, it is determined that the pressure of the fuel supplied to the fuel injection valve 2 deviates from the desired pressure due to an abnormality in the high-pressure fuel supply system, and the solenoid valve 13 is opened. The configuration may be such that control and correction of the injection pulse width for low pressure injection are performed.

FIG. 9 is a system configuration diagram of the fourth embodiment. In FIG. 9, the high-pressure fuel pump 6 is assumed to be an engine driving pump to which the driving force of the engine is transmitted via a belt (not shown). Further, in FIG. 9, the fuel pressure sensor 21 is different from that of FIG. 3 corresponding to the first embodiment.
Instead of the break sensor 27 for detecting the break of the belt.
(Belt breakage detecting means) is provided.

The breaking sensor 27 is a sensor for detecting whether or not the belt is wound between the pulleys,
Specifically, a sensor that detects the presence or absence of the belt when light is blocked by the belt or a sensor that mechanically contacts the belt to detect the presence or absence thereof may be used. Then, in the fourth embodiment, abnormality diagnosis and fail-safe control are executed as shown in the flowchart of FIG.

In the flowchart of FIG. 10, the detection result of the breakage sensor 27 is read in S31. And
In S32, the breakage (loss due to breakage) of the belt used for transmitting the driving force to the high-pressure fuel pump 6 is determined from the detection result of the breakage sensor 27. If it is determined that the belt is broken, it is presumed that the pump is stopped without transmitting the driving force to the high-pressure fuel pump 6, and the desired high-pressure fuel cannot be supplied to the fuel injection valve 2. S33
Then, the solenoid valve 13 is controlled to be opened to bypass the high pressure fuel pump 6 so that the fuel is supplied. Further, in S34, the injection pulse width is corrected to increase so as to correspond to the low pressure injection state. .

On the other hand, if it is determined in S32 that the belt is not broken, the solenoid valve 13 is kept closed in S35, and
At 36, control is performed by the normal injection pulse width. According to this configuration, even if the high pressure fuel pump 6 cannot be driven by the engine due to the breakage of the belt,
Since the control is immediately switched to the low-pressure injection control, it is possible to eliminate the influence of the high-pressure fuel pump 6 and continue to stably supply the required amount of fuel to the engine.

FIG. 11 is a system configuration diagram of the fifth embodiment. In FIG. 11, the high-pressure fuel pump 6 is assumed to be a pump driven by a motor. Also,
11, the fuel pressure sensor 21 is omitted as compared with FIG. 3 corresponding to the first embodiment, while the control unit 3 can monitor the drive voltage or current of the motor driving the high-pressure fuel pump 6. Is done.

Then, in the fifth embodiment, abnormality diagnosis and fail-safe control are executed as shown in the flowchart of FIG. In the flowchart of FIG. 12,
First, in S41, the drive voltage V of the motor for driving the high-pressure fuel pump 6 is read. In S42, the drive voltage V is
It is determined whether it is within the allowable range corresponding to the normal time.

If it is out of the allowable range, the process proceeds to S43,
It is determined whether or not the state of being out of the allowable range continues for a predetermined time or more. If the state in which the drive voltage V is out of the allowable range continues for a predetermined time or more, the process proceeds to S44, the solenoid valve 13 is controlled to be opened, and the bypass passage 12 is performed in S45.
Is opened and fuel is supplied to the fuel injection valve 2 by the supply pressure of the low-pressure fuel pump 9, and the increase correction of the injection pulse width is executed.

On the other hand, when it is determined in S42 that the drive voltage V is within the allowable range, or when it is determined in S43 that the state of being outside the allowable range has not continued for a predetermined time or more, S
Proceeding to 46, the solenoid valve 13 is held in the closed state, and in S47, the injection control with the normal injection pulse width corresponding to the high pressure fuel is performed. With this configuration, even if the high-pressure fuel pump 6 cannot be driven in a desired state due to a drop in the power supply voltage of the motor that drives the high-pressure fuel pump 6 or a disconnection in the motor drive circuit, low-pressure injection is possible. It is possible to supply the required amount of fuel after switching the state to stabilize the fuel pressure.

In the flowchart of FIG. 12 above,
Instead of the drive voltage V, the current in the drive motor of the high-pressure fuel pump 6 may be determined. FIG.
It is a system block diagram of 6th Embodiment. In FIG. 13, the fuel pressure sensor 21 of FIG. 3 corresponding to the first embodiment is shown.
Instead, a pump rotation speed sensor 28 (pump rotation speed detection means) for detecting the rotation speed of the high-pressure fuel pump 6 is provided.

Then, in the sixth embodiment, abnormality diagnosis and fail-safe control are executed as shown in the flowchart of FIG. In the flowchart of FIG. 14,
First, in S51, the rotational speed Np of the high-pressure fuel pump 6 detected by the pump rotational speed sensor 28 is read. S52
Then, it is determined whether or not the rotation speed Np is within an allowable range corresponding to the normal time.

If it is out of the allowable range, the process proceeds to S53,
It is determined whether or not the state of being out of the allowable range continues for a predetermined time or more. If the state in which the rotation speed Np is out of the allowable range continues for a predetermined time or more, the process proceeds to S54, the solenoid valve 13 is controlled to be opened, and the bypass passage is performed in S55.
An increase correction of the injection pulse width is executed so as to correspond to the state where 12 is opened and the fuel is supplied to the fuel injection valve 2 by the supply pressure by the low pressure fuel pump 9.

On the other hand, when it is determined in S52 that the rotation speed Np is within the allowable range, or when it is determined in S53 that the state of being outside the allowable range has not continued for a predetermined time or more,
In step S56, the solenoid valve 13 is held in the closed state, and in step S57, the injection control with the normal injection pulse width corresponding to the high pressure fuel is performed. According to such a configuration, in addition to a decrease in pump rotation speed due to a motor failure when the high-pressure fuel pump 6 is driven by a motor, an abnormality in the motor energization circuit, a decrease in power supply voltage, etc., driving force transmission is performed with or without a drive source. It is possible to diagnose the abnormality of the mechanism (belt or gear) and further the decrease of the pump rotation speed due to the failure of the high-pressure fuel pump 6 itself, so that the fuel pressure can be stabilized even when an abnormality occurs in these high-pressure fuel supply systems. Thus, the required amount of fuel can be supplied to the engine.

In each of the above embodiments, when an abnormality occurs in the high-pressure fuel supply system, the high-pressure fuel pump 6 is bypassed to correct the injection pulse width, but the injection pulse width is not corrected. Is also good. In this case, the required fuel amount cannot be secured, but it is possible to avoid a large change in the fuel supply pressure to the fuel injection valve due to an abnormality in the high-pressure fuel supply system, and at least to stabilize the fuel injection amount with respect to the injection pulse width. Therefore, the operational stability of the engine can be maintained.

[0052]

As described above, according to the spark ignition type internal combustion engine according to the invention of claim 1, an abnormality occurs in the high pressure fuel supply system including the high pressure fuel pump, and the desired pressure is applied to the fuel injection valve. When it becomes impossible to stably supply the fuel in, the high-pressure fuel pump is bypassed to supply the fuel to the fuel injection valve, so that the low-pressure fuel pump can stabilize the low-pressure injection state. This has the effect of maintaining the operational stability of the engine.

According to the spark ignition internal combustion engine of the second aspect of the present invention, when an abnormality that bypasses the high-pressure fuel pump occurs, the injection pulse width is increased and corrected to correspond to the low-pressure injection state. The effect is that the required amount of fuel can be injected and supplied. According to the spark ignition type internal combustion engine of the third aspect of the present invention, by detecting the fuel pressure on the downstream side of the high-pressure fuel pump, it is possible to reliably diagnose the abnormality of the fuel pressure and execute the bypass control. is there.

According to the spark ignition internal combustion engine of the fourth aspect of the present invention, by detecting the drive torque of the high pressure fuel pump, an abnormality such as seizure of the high pressure fuel pump can be diagnosed and the bypass control can be executed. The effect is that you can do it. According to the spark ignition type internal combustion engine of the invention of claim 5, when the fuel supply pressure to the fuel injection valve changes,
Since the amount of fuel actually injected and supplied changes with respect to the injection pulse width to change the air-fuel ratio, it is possible to indirectly diagnose the abnormality of the fuel supply pressure based on the air-fuel ratio and execute the bypass control. There is an effect that can be.

According to the spark ignition type internal combustion engine of the sixth aspect of the present invention, the injection amount due to the change in the fuel supply pressure is based on the difference between the actual air-fuel ratio and the expected air-fuel ratio based on the injection pulse width. There is an effect that the fluctuation of can be diagnosed with high accuracy. According to the spark ignition internal combustion engine of the invention of claim 7, in the configuration in which the high-pressure fuel pump is driven by the electric motor, the high-pressure fuel pump is driven at an intended rotational speed due to an abnormality in the drive voltage or drive current of the motor. There is an effect that it is possible to diagnose an abnormal state where the driving is stopped and to execute the bypass control.

According to the spark ignition internal combustion engine of the eighth aspect of the present invention, the motor abnormality when the high-pressure fuel pump is driven by the electric motor, or the driving force transmission mechanism such as the belt or gear when the engine is driven. Of the high-pressure fuel pump itself, and the abnormality of the high-pressure fuel pump itself causes the rotation speed of the high-pressure fuel pump to become abnormal, and the discharge amount of the high-pressure fuel pump is abnormal. There is an effect that can be.

According to the spark ignition type internal combustion engine of the ninth aspect of the present invention, even if the abnormality diagnosis parameter may instantaneously show an abnormal value in the normal state, the high pressure fuel supply system is based on this. There is an effect that it is possible to avoid erroneous diagnosis of abnormalities. According to the spark ignition internal combustion engine of the invention of claim 10, in the high-pressure fuel pump in which the driving force from the engine is transmitted through the belt, it becomes impossible to drive the high-pressure fuel pump due to the breakage of the belt. In this case, there is an effect that the bypass control can be executed in response to this.

[Brief description of drawings]

FIG. 1 is a basic configuration block diagram of the invention according to claim 1;

FIG. 2 is a basic configuration block diagram of the invention according to claim 2.

FIG. 3 is a system configuration diagram of the first embodiment.

FIG. 4 is a flowchart showing the control contents of the first embodiment.

FIG. 5 is a system configuration diagram of a second embodiment.

FIG. 6 is a flowchart showing the control content of the second embodiment.

FIG. 7 is a system configuration diagram of a third embodiment.

FIG. 8 is a flowchart showing the control contents of the third embodiment.

FIG. 9 is a system configuration diagram of a fourth embodiment.

FIG. 10 is a flowchart showing the control content of the fourth embodiment.

FIG. 11 is a system configuration diagram of a fifth embodiment.

FIG. 12 is a flowchart showing the control content of the fifth embodiment.

FIG. 13 is a system configuration diagram of a sixth embodiment.

FIG. 14 is a flowchart showing the control content of the sixth embodiment.

[Explanation of symbols]

 1 spark ignition type internal combustion engine 2 fuel injection valve 3 control unit 4 common rail 5 minute piping 6 high pressure fuel pump 7 high pressure regulator 8 fuel passage 9 low pressure fuel pump 10 fuel tank 11 low pressure regulator 12 bypass passage 13 solenoid valve (valve mechanism) 14a ~ 14c Check valve 21 Fuel pressure sensor 22 Drive torque sensor 23 Air-fuel ratio sensor 27 Breakage sensor 28 Pump speed sensor

Claims (10)

[Claims] 1. A spark ignition internal combustion engine comprising a high-pressure fuel pump for supplying fuel to a fuel injection valve and a low-pressure fuel pump for supplying fuel to the high-pressure fuel pump, and a bypass passage bypassing the high-pressure fuel pump. A valve mechanism for opening and closing the bypass passage; an abnormality diagnosing means for deciding whether or not there is an abnormality in the high-pressure fuel supply system including the high-pressure fuel pump; A spark ignition type internal combustion engine, comprising: a bypass control means for controlling the opening of the mechanism. 2. A pulse width correction for increasing and correcting an injection pulse width output to a fuel injection valve when the valve mechanism is controlled to be opened by the bypass control means so as to correspond to a fuel supply pressure by the low pressure fuel pump. The spark ignition type internal combustion engine according to claim 1, further comprising means. 3. The abnormality diagnosing means includes a fuel pressure detecting means for detecting a fuel pressure on the downstream side of the high-pressure fuel pump, and diagnoses the presence or absence of abnormality on the basis of the fuel pressure detected by the fuel pressure detecting means. Claim 1 characterized by the above.
Or the spark ignition internal combustion engine according to 2. 4. The abnormality diagnosing means includes driving torque detecting means for detecting the driving torque of the high-pressure fuel pump, and diagnoses the presence or absence of abnormality based on the driving torque detected by the driving torque detecting means. The spark ignition internal combustion engine according to claim 1 or 2, characterized in that. 5. The abnormality diagnosis means includes an air-fuel ratio detection means for detecting the air-fuel ratio of the engine intake air-fuel mixture, and diagnoses the presence or absence of abnormality based on the air-fuel ratio detected by the air-fuel ratio detection means. The spark ignition internal combustion engine according to claim 1 or 2, characterized in that. 6. The abnormality diagnosis means diagnoses the presence or absence of abnormality based on a difference between an air-fuel ratio detected by the air-fuel ratio detection means and an instruction air-fuel ratio obtained from an injection pulse width and an engine intake air amount. The spark ignition internal combustion engine according to claim 5, wherein 7. The high-pressure fuel pump is configured to be driven by an electric motor, and the abnormality diagnosis means diagnoses the presence or absence of abnormality based on at least one of a drive voltage and a drive current of the electric motor. The spark ignition internal combustion engine according to claim 1 or 2. 8. The abnormality diagnosis means includes a pump rotation speed detection means for detecting the rotation speed of the high pressure fuel pump, and is based on the rotation speed of the high pressure fuel pump detected by the pump rotation speed detection means. The spark ignition internal combustion engine according to claim 1 or 2, wherein the presence or absence of abnormality is diagnosed. 9. The abnormality diagnosing means determines an abnormality occurrence only when a value of a parameter to be judged for abnormality diagnosis is outside a predetermined allowable range for a predetermined time or more. The spark ignition type internal combustion engine according to claim 1. 10. The high-pressure fuel pump is an engine-driven pump, the driving force is transmitted by a belt, and the abnormality diagnosis means includes a belt breakage detection means for detecting breakage of the belt. 3. The spark ignition internal combustion engine according to claim 1 or 2, characterized in that an abnormality occurrence is determined when the breakage of the belt is detected by the belt breakage detection means.