JPH10331689A - Control device of engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To properly control an engine by speedily and efficiently restraining misfire due to vapor produced in an injector after starting of the engine. SOLUTION: This device is furnished with a vapor judgement means 41 to judge whether fuel in an injector 10 is in a state to easily produce foam or not, a flame-out judgement means 42 to judge whether flame-out is caused in an engine or not and an injection pressure control means 43 to control pressure of fuel injected from the injector 10. Thereafter, in the case of confirming that fuel in the injector 10 is in a state where vapor is easily produced by a vapor judgement means 41, injection pressure of fuel is controlled to rise by the injection pressure control means 43, and in the case of confirming that flame-out is caused by the flame-out judgement means 42 after starting the engine, it is constituted to correct a control state of the injection pressure control means 43 in a direction to restrain causing of flame-out due to production of vapor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine for controlling the occurrence of a misfire due to the generation of air bubbles when it is confirmed that air bubbles are easily generated in the fuel in the injector. Related to the control device.

[0002]

2. Description of the Related Art Conventionally, as disclosed in, for example, Japanese Patent Application Laid-Open No. 4-36044, in an engine misfire diagnosis apparatus, in order to reduce erroneous diagnosis and obtain high reliability, the start of a starter motor is started. By providing a misfire determination stop period for a certain period of time from the point in time and stopping the misfire determination until this period elapses, misfire due to generation of bubbles in the fuel in the injector is caused by failure of the injector, etc. The misfire is prevented from being erroneously diagnosed as having occurred and the misfire determination is executed after the elapse of the misfire determination stop period.

[0003] That is, if the engine is restarted in a high temperature state immediately after stopping the operation of the engine or the like, bubbles are easily generated in the fuel in the injector, and the fuel injection amount is temporarily reduced in accordance with the generated amount of the bubbles. The air-fuel ratio may decrease, causing a misfire or a partial misfire. Such a misfire or a semi-misfire is a temporary one that is resolved when the injector is cooled by fuel supplied to the injector thereafter, and it is determined that the misfire is not actually a misfire caused by a failure. Therefore, the occurrence of the erroneous diagnosis is prevented by prohibiting the misfire determination for a certain period of time from the start of driving of the starter motor.

[0004]

According to the structure disclosed in the above publication, the misfire determination is always stopped for a certain period of time after the start of the engine, even when the above-mentioned vapor is not generated. Since the diagnosis of misfire due to the above-mentioned failure is not performed until a certain time has elapsed after the start of the engine, the misfire due to the above-mentioned failure which adversely affects the exhaust gas purifying catalyst and deteriorates the emission is determined at an early stage. There is a problem that can not be.

[0005] For this reason, the fuel temperature in the injector is detected after the engine is started, and only when it is confirmed that bubbles are easily generated in the fuel in accordance with the detected value of the fuel temperature or the like, the fuel can be detected for a certain period of time. In addition to prohibiting the misfire determination over a long period of time, if it is confirmed that the bubble is not easily generated, the misfire determination is performed immediately after the engine is started. It is also conceivable to configure so that misfire caused by a failure or deterioration of the injector can be diagnosed at an early stage during normal times while preventing the occurrence of a misfire.

However, even in the case of the above-mentioned structure, if it is confirmed that bubbles are easily generated in the fuel according to the fuel temperature in the injector after the engine is started, the bubbles are removed. Therefore, it is inevitable that the detection of a misfire due to the failure is delayed. If the discovery of such a misfire is delayed, a large amount of unburned gas is mixed into the exhaust gas, and the unburned gas burns in the exhaust gas catalyst, thereby damaging the exhaust gas purification catalyst. It is desired to be able to diagnose the occurrence of misfire due to the above-mentioned failure at an early stage without making a determination.

[0007] In view of such circumstances, the present invention can quickly and effectively suppress a misfire due to the generation of bubbles in fuel in an injector after the engine is started, and appropriately control the engine. An object of the present invention is to provide an engine control device.

[0008]

The invention according to claim 1 is
Vapor determining means for determining whether air bubbles are likely to be generated in the fuel in the injector, misfire determining means for determining whether or not misfire has occurred in the engine, and the injection state of the fuel injected from the injector The injection state control means for controlling the fuel injection pressure is increased by the injection state control means when it is confirmed by the vapor determination means that air bubbles are easily generated in the fuel in the injector. Injection pressure control means for controlling the injection pressure control in a direction to suppress the occurrence of misfire due to the generation of bubbles when the misfire determination means confirms that misfire has occurred after the engine is started. The control state of the means is configured to be corrected.

According to the above construction, when it is confirmed by the vapor determination means that air bubbles are easily generated in the fuel in the injector, the injection pressure control means increases the injection pressure of the fuel. By performing the control, a temporary decrease in the fuel injection amount due to generation of bubbles in the fuel or the like in the injector is suppressed, and a misfire due to a lean air-fuel ratio is suppressed. Further, when it is confirmed that the misfire has occurred by the misfire determination means after the start of the engine, the control state of the injection pressure control means is corrected in a direction to suppress the occurrence of the misfire due to the generation of the bubbles. Thus, the misfire determination is executed in a state where the occurrence of the misfire due to the generation of bubbles in the fuel is promptly and effectively suppressed, and the diagnosis of the misfire failure or the like is appropriately performed based on the determination result. Will be executed.

According to a second aspect of the present invention, there is provided an engine control system as set forth in the first aspect, further comprising a vapor determination means for determining whether or not bubbles are easily generated in the fuel based on the temperature of the fuel in the injector. In the device, when it is confirmed that misfire has occurred by the misfire determination means after the start of the engine, the fuel temperature as a reference for determining whether or not the fuel is in a state in which bubbles are easily generated by the vapor determination means. By expanding the region to the low temperature side, a correction is made in a direction to suppress the occurrence of misfire due to the generation of the bubbles.

According to the above configuration, when it is confirmed by the misfire determining means that the engine has started after the engine has started, the vapor determining means determines whether or not bubbles are easily generated in the fuel. The fuel temperature region serving as a reference to be expanded is corrected to the low temperature side. Based on the corrected temperature region, there is a high possibility that misfire due to vapor has occurred. Is to be determined.

According to a third aspect of the present invention, in the engine control device according to the second aspect, bubbles are easily generated in the fuel in the injector based on at least one of the engine coolant temperature and the intake air temperature. It is configured to estimate a fuel temperature that is a criterion for determining whether or not the fuel temperature is high.

According to the above configuration, the fuel temperature in the injector is estimated after the engine is started by the vapor determination means in accordance with at least one of the engine coolant temperature and the intake air temperature. It is determined whether or not the control to suppress the vapor by increasing the injection pressure is performed.

[0014]

FIG. 1 shows the overall structure of an engine provided with a control device according to the present invention. In this figure, reference numeral 1 denotes an engine body having a cylinder, and an intake port 3 opened and closed by an intake valve and an exhaust port 4 opened and closed by an exhaust valve are opened in a combustion chamber 2 of the cylinder. An intake passage 5 is connected to the intake port 3, and an exhaust passage 13 is connected to the exhaust port 4.

In the intake passage 5, an air cleaner 6, an air flow sensor 7, and a throttle valve 8 are arranged in this order from the upstream side.
And a surge tank 9, and an injector 10 for injecting fuel is provided near the intake port 3. Further, an ISC passage 11 that bypasses the throttle valve 8 is provided in the intake passage 5.
The SC passage 11 is provided with an ISC valve 12 that adjusts an air flow rate to execute idle speed control. On the other hand, the O ₂ sensor 14 and the catalyst device 1
5 and the like are provided.

The fuel system for supplying fuel to the injector 10 includes a fuel tank 20, a fuel pump 21, a fuel supply passage 22, and a return passage 23.
The fuel is sent to the injector 10 through the. A fuel filter 24 is provided in the fuel supply passage 22. Further, the return passage 23
Is provided with a pressure regulator 25 for adjusting the fuel pressure according to the intake pressure.

The pressure regulator 25 normally generates a differential pressure between a negative pressure introduced into the negative pressure chamber from a downstream portion of the throttle valve 8 in the intake passage 5 and an injection pressure of fuel injected from the injector 10. In addition to maintaining the pressure constant, a negative pressure cut valve 27
Thus, the negative pressure introduced into the negative pressure chamber is shut off, and the atmospheric pressure is introduced into the negative pressure chamber, thereby increasing the fuel injection pressure. That is, the pressure regulator 25 and the negative pressure cut valve 2
3 constitutes an injection state control means for controlling the injection state of the fuel injected from the injector 10.

The engine body 1 is provided with a crank angle sensor 17 for detecting the rotation speed of the crankshaft and a water temperature sensor 18 for detecting the temperature of the cooling water for the engine. An intake air temperature detecting means including an intake air temperature sensor 26 for detecting a temperature is provided. The operating states of the injector 10 and the pressure regulator 25 are controlled in accordance with a control signal output from a control unit 40 of the engine.

The engine control unit 40 controls the amount of fuel injected from the injector 10 according to the operating state of the engine.
When it is confirmed that vapor generating bubbles is generated in the fuel in a fuel supply pipe (not shown) that supplies the fuel in the fuel tank to the injector 10, the pressure is reduced by the negative pressure cut valve 27. By controlling the supply of the negative pressure to the negative pressure chamber of the regulator 25 to increase the injection pressure of the fuel, a function of eliminating the vapor at an early stage is provided.

That is, the control unit 40 determines whether the fuel in the injector 10 is in a state in which bubbles are easily generated in the fuel, and whether the engine has misfired. Misfire determining means 42,
An injection pressure control means 43 for controlling the injection pressure of the fuel injected from the injector 10 is provided. Then, the injector 10 is determined by the vapor determination unit 41.
When it is confirmed that bubbles are easily generated in the fuel in the chamber, a control signal is output from the injection pressure control means 43 to the negative pressure cut valve 27, and the atmospheric pressure is supplied to the negative pressure chamber of the pressure regulator 25. Is controlled so as to increase the fuel injection pressure to suppress the vapor at an early stage.

The vapor determining means 41 is provided with the water temperature sensor 1.
8 and at least one of the engine coolant temperature and the intake air temperature detected by the intake air temperature sensor 26 are higher than a predetermined reference temperature.
It is determined that bubbles are likely to be generated in the fuel in the injector 10 and that there is a possibility that so-called vapor is generated, and this vapor determination signal is sent to the injection pressure control means 4.
3 is output.

Further, the misfire determining means 42 calculates a variation value of the crank angular speed which is a difference between the present crank angular speed and the previous crank angular speed based on the detection signal output from the crank angle sensor 18, and When the variation value of the crank angular velocity exceeds a predetermined determination value, it is determined that a misfire has occurred, the number of occurrences of the misfire is counted, and the misfire determination signal and the misfire count signal are transmitted to the injection pressure control means 43. Is configured to be output. This misfire determination is performed after the engine is started until the engine is stopped.

The injection pressure control means 43 determines that at least one of the cooling water temperature and the intake air temperature at the start of the engine is 100 ° C.
When it is confirmed that the temperature is higher than a first reference temperature preset at about 0 ° C., a control signal for increasing the injection amount of the fuel injected from the injector 10 compared with the normal time is output to the injector 10. It is configured to be.

The injection pressure control means 43 determines that at least one of the cooling water temperature and the intake air temperature of the engine is reduced to about 90 ° C. and 60 ° C. within a predetermined time after the start of the engine. When it is confirmed that the temperature is higher than the second reference temperature set in advance, the control signal for increasing the injection pressure of the fuel injected from the injector 10 as compared with normal time is transmitted to the negative pressure cut valve 2.
7.

Further, the injection pressure control means 43 determines that at least one of the cooling water temperature and the intake air temperature of the engine is equal to or lower than the second reference temperature within a predetermined time after the start of the engine. Is confirmed, the misfire determination means 42 confirms that a misfire has occurred, and the vapor determination means 41
It is confirmed that at least one of the engine cooling water temperature and the intake air temperature is higher than the third reference temperature preset at about 70 ° C. and 50 ° C., and the misfire counted by the misfire determination means 42 If it is confirmed that the number of times is greater than the predetermined reference number, it is determined that vapor is likely to occur, and the injector 10
The control signal for increasing the injection pressure of the fuel injected from the normal pressure is output to the negative pressure cut valve 27.

Further, the control unit 40 is provided with misfire failure diagnosis means for diagnosing whether or not a misfire has occurred due to a failure or deterioration of the injector 10, the spark plug and the O2 sensor 14. This misfire failure diagnosis means is provided for the misfire caused by the vapor, which occurs intensively after the start of the engine and whose frequency of occurrence tends to decrease with time, and the failure which tends to occur at a constant frequency. It is configured to diagnose the occurrence of a misfire failure by determining the misfire caused by the misfire based on the frequency of occurrence of the misfire.

The control operation of the engine executed by the engine control device having the above configuration will be described with reference to the flowcharts of FIGS. When the control operation starts, first, it is determined whether or not the starter SW for operating the starter motor has been turned on (step S).
1) When YES is determined, the starter motor is operated to crank the engine (step S2).

Next, after resetting a count value Tst of a post-start timer for measuring an elapsed time after starting the engine to 0 (step S3), the count value of the number of misfires counted by the misfire determination means 42 and a counter are used. The measured value Chke of the diagnosis period corresponding to the measured integrated value of the engine speed and the like is reset to 0 (step S4), and whether or not the misfire has been confirmed by the misfire determination means 42 is determined. Resets the indicated misfire flag F to 0 (step S
5).

In addition, while detecting the operating state of the engine based on the detection signal of each sensor (step S6),
After inputting the detection values of the water temperature sensor 18 and the intake air temperature sensor 26 as the engine cooling water temperature thw and the intake air temperature tha (step S7), the engine rotation speed indicating that the engine has completely exploded becomes greater than 1000 rpm. It is determined whether the engine has started by determining whether the engine has started (step S8). If NO is determined in this step S8, the water temperature sensor 18
And the detected value of the intake air temperature sensor 26 as the cooling water temperature t at the time of starting.
After inputting hws and the intake air temperature as (step S9), the process returns to step S3.

Then, when the result of the determination in step S8 is YES, the count value Tst of the post-start timer is set.
Is incremented by 1 (step S10), and then it is determined whether or not 5 seconds or more have elapsed after the start of the engine, and whether or not the engine is in a low load / low rotation state. It is determined whether or not the condition is satisfied (step S11). If YES is determined in this step S11, the misfire is monitored by the misfire determination means 42 (step S12), and then the presence or absence of a misfire is determined according to the result of the monitoring (step S13).

If YES is determined in the step S13, the misfire flag F is set to 1 (step S14), and the count value CMS of the number of misfires is set.
After incrementing F by 1 (step S15),
The vapor determination means 45 determines whether or not the count value Tst of the post-start timer is less than 30 seconds (step S16), and sets the engine-starting coolant temperature thws detected by the water temperature sensor 18 in advance. Is higher than the first reference temperature W1 of about 100 ° C., and whether the intake air temperature when detected by the intake air temperature sensor 26 at the start of the engine is higher than the first reference temperature A1 set to about 60 ° C. It is determined whether or not the fuel in the injector 10 is in a state where air bubbles are easily generated by determining whether or not the fuel is in the injector 10 (steps S17 and S18).

In steps S16 to S18, Y
When it is determined as ES and it is confirmed that the fuel in the injector 10 is in a state where vapor is easily generated, the injection amount of the fuel injected from the injector 10 into the intake port 3 of the cylinder in which the misfire has occurred is determined. A correction for increasing the amount is performed (step S19), and the process proceeds to step S20 described below. If NO is determined in any of steps S16 to S18, the process directly proceeds to step S20 without performing the increase correction of the fuel injection amount.
It is determined whether or not the count value Tst of the post-start timer is smaller than a predetermined threshold value B set as a function of the engine coolant temperature thw and the intake air temperature tha.

Then, YES is determined in the step S20, and it is determined that the count value Tst of the post-start timer is smaller than the threshold value B set as a function of the engine coolant temperature thw and the intake air temperature tha. When it is confirmed that the engine temperature is within the predetermined period after the start of the engine, the detected value of the engine cooling water temperature thw detected by the water temperature sensor 18 at the present time is lower than the first reference temperature W1. 80 ° C set to the value
It is determined whether the temperature is higher than the second reference temperature W2 (step S21), and the detected value of the intake air temperature th at the present time detected by the intake air temperature sensor 26 is:
60 ° set to a value lower than the first reference temperature A1
By determining whether or not the temperature is higher than the second reference temperature A2 of about C (step S22), it is determined whether or not the fuel in the injector 10 is in a state where bubbles are easily generated.

The above steps S21 and S22
If YES is determined in step S23, a control signal for introducing atmospheric pressure into the negative pressure chamber of the pressure regulator 25 is output to the negative pressure cut valve 27 to increase the fuel injection pressure (step S23). , Step S6
And the above control operation is repeated. In any of the above-described steps S21 and S22, N
If it is determined to be O, it is determined whether or not the misfire flag F is set to 1, that is, whether or not the misfire has been detected by the misfire determination means 41 after the engine is started (step S24). ).

If the result of the determination in step S24 is YES and it is confirmed that the misfire flag F has been set to 1, the detected value of the engine coolant temperature thw at the present time is determined by the second It is determined whether the temperature is higher than a third reference temperature W3 of about 70 ° C. set to a value lower than the reference temperature W2 (step S25).
It is determined whether or not the detected value of the intake air temperature at the present time is higher than a third reference temperature A3 of about 50 ° C. which is set to a value lower than the first reference temperature A2 (step S).
26) Further, by determining whether or not the count value CMSF of the number of misfires counted in step S19 is larger than a preset reference value, for example, five times (step S27), the fuel in the injector 10 is determined. A re-determination is made as to whether or not the air bubble is in a state where air bubbles are easily generated.

In steps S24 to S27, Y
If it is determined as ES and it is confirmed that bubbles are easily generated in the fuel in the injector 10 within a predetermined time after the start of the engine, the process proceeds to step S2.
3, the control signal for introducing the atmospheric pressure into the negative pressure chamber of the pressure regulator 25 is transmitted to the negative pressure cut valve 27.
To increase the fuel injection pressure.

On the other hand, if NO is determined in any of the steps S20, S24 and S25 to S27, and it is confirmed that the fuel is not in a state in which bubbles are easily generated, the routine proceeds to step S28, where the diagnosis period is determined. Measured value C
After counting hke, in step S29, it is determined whether or not the measured value Chke is equal to a reference time a consisting of an integrated value of the engine speed set to about 1000 rotations. It is determined whether or not a diagnostic period for diagnosing whether or not a misfire failure that has an adverse effect or deteriorates emission has occurred. If NO is determined in step S29, the process returns to step S6 to repeat the control operation.

If the result of the determination in step S29 is YES and it is confirmed that the diagnosis period has elapsed, the measured value Chke is cleared in step S30 and then counted in step S15. It is determined whether or not the count value CMSF of the number of misfires is greater than a predetermined reference value b. If the determination is NO, the count value CMSF is determined in step S31.
Is cleared, the process returns to step S6, and the above control operation is repeated.

If the result of the determination in step S31 is YES and it is confirmed that the count value CMSF of the number of misfires is larger than the reference value b, the failure of the injector 10 is determined in a state where fuel vapor is not generated. Alternatively, it is considered that the misfire caused by the failure or deterioration of the O2 sensor 14 causes the count value CMSF of the number of misfires to be larger than a predetermined reference value b. After turning on the warning light indicating that the alarm has occurred, the control operation ends.

The vapor determining means 41 for determining whether the fuel in the injector 10 is in a state where air bubbles are likely to be generated, the misfire determining means 42 for determining whether or not a misfire has occurred in the engine, And an injection pressure control means 43 for controlling the injection state control means comprising the pressure regulator 25 and the negative pressure cut valve 27 to control the injection pressure of the fuel. In the vapor determination means 41, bubbles in the fuel in the injector 10 are generated. If it is confirmed that the injection pressure is easily generated, the injection pressure control means 43
The fuel injection pressure is controlled so as to increase the fuel injection pressure, and when the misfire determination means 42 confirms that a misfire has occurred after the engine is started, the injection pressure control means 43 is controlled to suppress the occurrence of misfire. Since the control state is corrected, misfire of the engine can be quickly and appropriately diagnosed.

That is, after the engine is started, if the detected values of the cooling water temperature thw and the intake air temperature tha of the engine are confirmed to be higher than the second reference temperatures W2 and A2 set in advance by the vapor determining means 41. Since the injection pressure of the fuel adjusted by the pressure regulator 25 or the like is increased by the injection pressure control means 43 by judging that the fuel in the injector 10 is in a state where bubbles are easily generated in the fuel, the injector 10
The high-pressure fuel supplied to the inside can remove the bubbles at an early stage, and can effectively suppress the occurrence of misfire due to the lean air-fuel ratio.

The detected values of the cooling water temperature thw and the intake air temperature tha of the engine correspond to the second reference temperature W
Even if it is determined that the engine speed is equal to or less than A2, it is possible that the misfire is determined by the misfire determination means 42 within a predetermined time after the start of the engine, and the misfire caused by the vapor occurs. If the detected value is higher than the third reference temperature W3, A3 obtained by expanding the second reference temperature W2, A2 to the lower temperature side, the injection pressure is determined. Is configured to continue the misfire diagnosis in a state where vapor is suppressed by raising
The vapor determination map is corrected so as to be expanded from the normal region α shown by the solid line in FIG. 5 to the region β shown by the broken line. It is possible to diagnose misfire in a state where the influence of the misfire is suppressed, and it is possible to reliably determine whether misfire has occurred due to factors other than vapor.

Therefore, when the engine is started, it is reliably determined that fuel vapor is easily generated in the injector 10 or the like, and the injection pressure of the fuel is increased by the injection pressure control means 43. The vapor can be effectively eliminated by eliminating bubbles in the injector 10, and the misfire diagnosis by the misfire failure diagnosing means can be appropriately performed after that to cause the failure of the injector 10 and the spark plug. severe misfire malfunction or, O ₂ mild misfire failure or the like due to deterioration of the sensor 32, it is possible to rapidly and accurately diagnose.

In the above embodiment, the water temperature sensor 19
By estimating the fuel temperature in the injector 10 based on at least one of the engine coolant temperature and the intake air temperature detected by the intake air temperature sensor 26,
Since it is configured to determine whether or not bubbles are easily generated in the fuel, it is easy to determine whether or not bubbles are generated in the fuel in the injector 10 by using the existing sensor. And it can be determined accurately.

Further, in the above-described embodiment, immediately after the start of the engine, the cooling water temperature thws and the intake air temperature as of the engine detected by the water temperature sensor 18 and the intake air temperature sensor 26 are set in advance by the vapor determination means 41. When it is confirmed that the temperature is higher than the first reference temperature W1 or A1, the injection pressure control means 43 is configured to execute the correction for increasing the fuel injection amount. Can be suppressed.

The fuel temperature region, which is a reference for judging whether or not air bubbles are easily generated in the fuel by the vapor judging means 41, is expanded and corrected to a lower temperature side. Instead of the above-described embodiment configured to suppress the occurrence of the misfire, the fuel injection pressure controlled by the injection pressure control means 43 is corrected to suppress the occurrence of the misfire. Is also good. That is, after the engine is started, if it is confirmed that the misfire has occurred in the misfire determination means 42, and if the fuel temperature is equal to or higher than the second reference temperature W2, A2,
The injection pressure of the fuel, which is increased in pressure by the injection pressure control means 43, is compared with the case where the occurrence of misfire is not confirmed.
By performing the correction to further increase, the bubbles generated in the fuel in the injector 10 may be quickly removed, and the occurrence of misfire due to the generation of the bubbles may be effectively suppressed.

If it is confirmed by the misfire determination means 42 that the misfire has occurred after the start of the engine, the injection pressure control means 43 determines the time required to increase the fuel injection pressure by checking the occurrence of the misfire. Compared to the case where no air bubbles are generated, air bubbles generated in the fuel in the injector 10 are reliably removed by performing the correction to increase the length of the fuel, and the occurrence of misfire caused by the generation of the air bubbles is effectively suppressed. May be.

[0048]

As described above, according to the present invention, there is provided a vapor determining means for determining whether or not air bubbles are easily generated in the fuel in the injector, and a determination as to whether or not misfire has occurred in the engine. The misfire determination means, the injection state control means for controlling the injection state of the fuel injected from the injector, and the above-described vapor determination means when it is confirmed that bubbles are easily generated in the fuel in the injector, Injection pressure control means for controlling the injection pressure of the fuel to be increased by the injection pressure control means, and when the misfire determination means confirms that a misfire has occurred after the engine is started, the injection pressure control means is used to generate the bubbles. Since the control state of the injection pressure control means is corrected so as to suppress the occurrence of misfires caused by the occurrence of the Even if it is considered that a misfire has occurred, by controlling the vapor to be suppressed, the vapor generated in the injector can be eliminated at an early stage. There is an advantage that it is possible to quickly and accurately diagnose whether or not a severe misfire failure caused by a failure of the ignition plug or a spark plug or a mild misfire failure caused by a deterioration of the O ₂ sensor or the like has occurred.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating an example of an engine including a control device according to an embodiment of the present invention.

FIG. 2 is a flowchart illustrating a first step of an engine control operation.

FIG. 3 is a flowchart showing a second step of misfire diagnosis control.

FIG. 4 is a flowchart showing a third step of misfire diagnosis control.

FIG. 5 is a flowchart showing a third step of misfire diagnosis control.

FIG. 6 is a graph showing a vapor determination area.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Injector 25 Pressure regulator (injection state control means) 27 Negative pressure cut valve (injection state control means) 40 Engine control unit 41 Vapor determination means 42 Misfire determination means 43 Injection pressure control means

Claims (3)

[Claims] 1. A vapor determining means for determining whether air bubbles are easily generated in fuel in an injector, a misfire determining means for determining whether or not a misfire has occurred in an engine, and a fuel injected from the injector. Injection state control means for controlling the injection state of the fuel, and when the vapor determination means confirms that the fuel in the injector is in a state in which air bubbles are likely to be generated, the injection state control means controls the fuel injection pressure. Injection pressure control means for controlling the pressure to rise so as to suppress the occurrence of a misfire caused by the generation of bubbles when the misfire determination means confirms that a misfire has occurred after the engine is started. An engine control device characterized in that the control state of the injection pressure control means is corrected. 2. The engine control device according to claim 1, further comprising a vapor determination unit configured to determine whether or not air bubbles are easily generated in the fuel based on the fuel temperature in the injector. If the misfire determination unit later confirms that a misfire has occurred, by expanding the fuel temperature region, which is a reference for determining whether to increase the fuel injection pressure, to a lower temperature side, the generation of the bubbles is reduced. An engine control device configured to perform a correction in a direction to suppress the occurrence of misfire caused by the engine. 3. The engine control device according to claim 2, wherein a criterion for determining whether or not air bubbles are easily generated in the fuel in the injector based on at least one of a cooling water temperature of the engine and an intake air temperature. A control device for an engine, wherein the control device is configured to estimate a fuel temperature.