JP2017082695A - Start control device of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure the startability of an engine even at an abnormality of high-fuel pressure, in a system for supplying fuel discharged from a high-pressure pump to a fuel injection valve.SOLUTION: When it is determined that fuel pressure in a high-pressure fuel passage exceeds a high-fuel pressure determination value within a prescribed time after the determination of the completion of a start of an engine, a starter relay is turned on, and the cranking of the engine is restarted at a time point t4 of the determination. Furthermore, a relief valve is opened at a time point t5 at which the fuel pressure exceeds the high-fuel pressure determination value, and becomes higher than the valve-opening pressure of the relief valve, and the fuel pressure is lowered to fuel pressure which is lower than the high-fuel pressure abnormality determination value. At this time, when the fuel pressure becomes not higher than the high-fuel pressure abnormality determination value, the fuel injection of a fuel injection valve is restarted. By this constitution, even if the fuel pressure exceeds the high-fuel pressure abnormality determination value immediately after the determination of the completion of the start of the engine, and the fuel injection becomes impossible by the fuel injection valve, the cranking of the engine and the fuel injection of the fuel injection valve are restarted, and the engine is restarted.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a start control device for an internal combustion engine that supplies fuel discharged from a high-pressure pump to a fuel injection valve.

  In-cylinder injection type internal combustion engines have a short injection-to-combustion time compared to intake port injection type internal combustion engines, and it is not possible to earn enough time to atomize the injected fuel. Therefore, it is necessary to atomize the injected fuel. Therefore, the fuel pumped up from the fuel tank by the electric low-pressure pump is supplied to the high-pressure pump driven by the power of the internal combustion engine, and the high-pressure fuel discharged from the high-pressure pump is pumped to the fuel injection valve. Yes.

  In such a system, if an abnormality occurs in the high-pressure pump, the control system, etc., the fuel pressure (that is, fuel pressure) in the high-pressure fuel passage may become abnormally high. If the fuel pressure exceeds the opening limit pressure of the fuel injection valve when the fuel pressure in the high-pressure fuel passage becomes abnormally high and the fuel pressure exceeds the opening limit pressure of the fuel injection valve, there is a possibility that the fuel injection valve cannot be opened and fuel injection cannot be performed. Therefore, as described in Patent Document 1, the valve opening limit pressure of the fuel injection valve is set to be equal to or higher than the maximum fuel pressure when the high fuel pressure is abnormal, and the fuel injection valve is operated against the fuel pressure even when the high fuel pressure is abnormal. There is one that can be opened to perform fuel injection.

Japanese Patent No. 5525760

  In order to meet the recent demands for improving fuel consumption and reducing emissions, there is a further demand for higher fuel pressure and higher injection pressure, and accordingly, fuel pressure during high fuel pressure abnormalities also tends to increase. It is also required to ensure the startability of the internal combustion engine even when the high fuel pressure is abnormal.

  However, if the valve opening limit pressure of the fuel injection valve is set to be equal to or higher than the maximum fuel pressure when the high fuel pressure is abnormal so that fuel injection can be performed even when the high fuel pressure is abnormal, as in the technique of Patent Document 1, the fuel It is necessary to take measures to increase the size of the injection valve and the heat generated by the control circuit. For this reason, there exists a problem of causing the cost increase of a fuel injection valve or a control circuit, and the mounting property deterioration.

  Therefore, the problem to be solved by the present invention is to start the internal combustion engine that can ensure the startability of the internal combustion engine even when the fuel pressure is abnormal while suppressing the increase in cost and deterioration of the mountability of the fuel injection valve and the control circuit. It is to provide a control device.

  In order to solve the above problems, the invention according to claim 1 is directed to a low pressure fuel passage (13) for supplying fuel discharged from the low pressure pump (12) to the high pressure pump (14), and fuel discharged from the high pressure pump. And the high pressure fuel passages (26, 27) for supplying the fuel to the fuel injection valve (28) of the internal combustion engine, and when the internal combustion engine is started, the rotational speed of the internal combustion engine exceeds the start determination value and the start completion is determined. In a start control device for an internal combustion engine having a start control unit (39) for terminating cranking, the fuel pressure in the high pressure fuel passage (hereinafter referred to as "fuel pressure") corresponds to the upper limit fuel pressure at which fuel can be injected by the fuel injection valve. An abnormality determination unit (39) for determining whether or not a high fuel pressure abnormality determination value is exceeded, and a fuel return passage (30) for returning the fuel in the high pressure fuel passage to the low pressure fuel passage, and the fuel pressure in the high pressure fuel passage Is high fuel pressure abnormality When the valve opening pressure set on the high pressure side becomes higher than the fixed value, the valve opens and the fuel pressure in the high pressure fuel passage becomes lower than the valve closing pressure set on the low pressure side than the high fuel pressure abnormality judgment value. A relief valve (31) that closes when the internal combustion engine is started, and when it is determined that the fuel pressure in the high-pressure fuel passage has exceeded a high fuel pressure abnormality determination value within a predetermined period from the start completion determination of the internal combustion engine And a fail safe control unit (39) for restarting cranking of the internal combustion engine.

  In this configuration, a relief valve is provided in the fuel return passage for returning the fuel in the high-pressure fuel passage to the low-pressure fuel passage, and the valve opening pressure of the relief valve is set higher than the high fuel pressure abnormality determination value, Is set to a lower pressure side than the high fuel pressure abnormality determination value. For this reason, when the fuel pressure in the high-pressure fuel passage exceeds the high fuel pressure abnormality judgment value and becomes higher than the valve opening pressure of the relief valve, the relief valve opens and the fuel pressure in the high-pressure fuel passage exceeds the high fuel pressure abnormality judgment value. Also decreases to a low fuel pressure.

  When the internal combustion engine is started, cranking of the internal combustion engine is ended when the rotation speed of the internal combustion engine exceeds the start determination value and the start completion determination is made. However, after that, if the fuel pressure in the high pressure fuel passage exceeds the high fuel pressure abnormality judgment value (that is, the value corresponding to the upper limit fuel pressure at which the fuel injection valve can inject fuel) due to an abnormality of the high pressure pump or the like, the fuel injection valve Because it becomes impossible, combustion of the internal combustion engine stops.

  Therefore, in the invention according to claim 1, when it is determined at the start of the internal combustion engine that the fuel pressure in the high pressure fuel passage has exceeded the high fuel pressure abnormality determination value within a predetermined period from the start completion determination of the internal combustion engine, Restart cranking. Furthermore, when the fuel pressure in the high pressure fuel passage exceeds the high fuel pressure abnormality judgment value and becomes higher than the relief valve opening pressure, the relief valve opens and the fuel pressure is lower than the high fuel pressure abnormality judgment value. To fall. At that time, when the fuel pressure becomes equal to or lower than the high fuel pressure abnormality determination value, the fuel injection of the fuel injection valve is resumed.

  As a result, even if the fuel pressure in the high-pressure fuel passage exceeds the high fuel pressure abnormality determination value immediately after the completion of start of the internal combustion engine and fuel injection cannot be performed by the fuel injection valve, the cranking of the internal combustion engine and the fuel injection valve The internal combustion engine can be restarted quickly by restarting the fuel injection. In addition, it is not necessary to set the valve opening limit pressure of the fuel injection valve (that is, the upper limit fuel pressure at which fuel injection is possible) to be equal to or higher than the maximum fuel pressure when the high fuel pressure is abnormal (for example, the valve opening pressure of the relief valve). For this reason, the valve opening limit pressure of the fuel injection valve can be set to a relatively low value, and it is not necessary to take much measures to increase the size of the fuel injection valve and the accompanying control circuit. As a result, it is possible to ensure the startability of the internal combustion engine even when the fuel pressure is abnormal while suppressing an increase in the cost of the fuel injection valve and the control circuit and a deterioration in the mountability.

  Further, in the invention according to claim 3, when it is determined that the fuel pressure in the high pressure fuel passage has exceeded the high fuel pressure abnormality determination value during the previous operation of the internal combustion engine, the rotation of the internal combustion engine is started when the internal combustion engine is started. A fail-safe control unit (39) that continues cranking of the internal combustion engine even after the speed exceeds the start determination value is provided.

  In this configuration, when it is determined that the fuel pressure in the high-pressure fuel passage has exceeded the high fuel pressure abnormality determination value during the previous operation of the internal combustion engine, the fuel pressure in the high-pressure fuel passage is high when the internal combustion engine is started this time. It is judged that there is a high possibility that the fuel injection valve will not be able to inject fuel beyond the abnormality judgment value, and the cranking of the internal combustion engine will continue even after the internal combustion engine speed exceeds the start judgment value at the start of the internal combustion engine. Continue. Furthermore, when the fuel pressure in the high pressure fuel passage exceeds the high fuel pressure abnormality judgment value and becomes higher than the relief valve opening pressure, the relief valve opens and the fuel pressure is lower than the high fuel pressure abnormality judgment value. To fall. At that time, when the fuel pressure becomes equal to or lower than the high fuel pressure abnormality determination value, the fuel injection of the fuel injection valve is resumed.

  As a result, even if the fuel pressure in the high-pressure fuel passage exceeds the high fuel pressure abnormality determination value immediately after the rotational speed of the internal combustion engine exceeds the start determination value, it becomes impossible to inject fuel with the fuel injection valve. And restarting the fuel injection of the fuel injection valve, the internal combustion engine can be restarted quickly. Thereby, substantially the same effect as that of claim 1 can be obtained.

FIG. 1 is a diagram showing a schematic configuration of a control system for a direct injection type engine in Embodiment 1 of the present invention. FIG. 2 is a time chart showing the behavior of the fuel pressure before and after the relief valve is opened. FIG. 3 is a time chart illustrating an execution example of the start control according to the first embodiment. FIG. 4 is a flowchart illustrating a process flow of the start control routine according to the first embodiment. FIG. 5 is a flowchart showing the flow of processing of the injection permission determination routine of the first embodiment. FIG. 6 is a time chart illustrating an execution example of the start control according to the second embodiment. FIG. 7 is a flowchart showing the flow of processing of the injection permission determination routine of the second embodiment. FIG. 8 is a time chart illustrating an execution example of the start control according to the third embodiment. FIG. 9 is a flowchart showing the flow of processing of the high fuel pressure abnormality determination routine of the third embodiment. FIG. 10 is a flowchart showing the flow of processing of the start control routine of the third embodiment.

  Hereinafter, some embodiments embodying the mode for carrying out the present invention will be described.

A first embodiment of the present invention will be described with reference to FIGS.
First, a schematic configuration of a control system for an in-cylinder injection engine that is an in-cylinder injection internal combustion engine will be described with reference to FIG.

  An electric low-pressure pump 12 that pumps up the fuel is installed in the fuel tank 11 that stores the fuel. The fuel discharged from the low pressure pump 12 is supplied to the high pressure pump 14 through the low pressure fuel pipe 13 corresponding to the low pressure fuel passage. A pressure regulator 15 is connected to the low-pressure fuel pipe 13. The pressure regulator 15 adjusts the discharge pressure of the low-pressure pump 12 (that is, the fuel supply pressure to the high-pressure pump 14) to a predetermined pressure, and surplus fuel exceeding the pressure is returned into the fuel tank 11 by the fuel return pipe 16. It is supposed to be.

  The high-pressure pump 14 is a plunger pump that sucks / discharges fuel by reciprocating a plunger 19 in a cylindrical pump chamber 18. The plunger 19 is driven by the rotational motion of a cam 21 fitted on the cam shaft 20 of the engine. On the suction port side of the high-pressure pump 14, a fuel pressure control valve 23 comprising a normally open type electromagnetic valve is provided.

  The fuel pressure control valve 23 is opened during the intake stroke of the high-pressure pump 14 (that is, when the plunger 19 is lowered), the fuel is sucked into the pump chamber 18, and the fuel pressure is discharged during the discharge stroke of the high-pressure pump 14 (that is, when the plunger 19 is raised). The energization of the fuel pressure control valve 23 is controlled so that the control valve 23 is closed and the fuel in the pump chamber 18 is discharged.

  At that time, by controlling the energization start timing of the fuel pressure control valve 23 and controlling the valve closing period of the fuel pressure control valve 23, the discharge amount of the high-pressure pump 14 is controlled to control the fuel pressure (that is, the fuel pressure). For example, when raising the fuel pressure, the energization start timing of the fuel pressure control valve 23 is advanced to advance the valve closing start timing of the fuel pressure control valve 23. Thereby, the valve closing period of the fuel pressure control valve 23 is lengthened and the discharge amount of the high-pressure pump 14 is increased. Conversely, when the fuel pressure is reduced, the energization start timing of the fuel pressure control valve 23 is retarded and the valve closing start timing of the fuel pressure control valve 23 is retarded. Thereby, the valve closing period of the fuel pressure control valve 23 is shortened, and the discharge amount of the high-pressure pump 14 is reduced.

  On the other hand, a check valve 25 for preventing the backflow of discharged fuel is provided on the discharge port side of the high-pressure pump 14. The high-pressure fuel discharged from the high-pressure pump 14 is sent to the delivery pipe 27 through the high-pressure fuel pipe 26. High-pressure fuel is distributed from the delivery pipe 27 to a fuel injection valve 28 attached to each cylinder of the engine. The fuel injection valve 28 is a fuel injection valve for in-cylinder injection that directly injects fuel into the cylinder. The high-pressure fuel pipe 26 or the delivery pipe 27 is provided with a fuel pressure sensor 29 that detects the fuel pressure in the high-pressure fuel passage such as the high-pressure fuel pipe 26 or the delivery pipe 27.

  Further, the high pressure pump 14 is provided with a fuel return passage 30 for returning the fuel in the high pressure fuel pipe 26 to the low pressure fuel pipe 13. A relief valve 31 is provided in the middle of the fuel return passage 30. The relief valve 31 opens when the fuel pressure in the high pressure fuel passage becomes higher than a predetermined valve opening pressure, and closes when the fuel pressure in the high pressure fuel passage becomes lower than a predetermined valve closing pressure. I speak. Here, the valve opening pressure of the relief valve 31 is set to a higher pressure side (for example, 45 MPa) than the high fuel pressure abnormality determination value corresponding to the upper limit fuel pressure at which the fuel injection valve 28 can inject fuel. On the other hand, the valve closing pressure of the relief valve 31 is set to a lower pressure side (for example, a fuel pressure lower than the target fuel pressure) than the high fuel pressure abnormality determination value. As a result, as shown in FIG. 2, when the fuel pressure in the high pressure fuel passage exceeds the high fuel pressure abnormality determination value and becomes higher than the valve opening pressure of the relief valve 31, the relief valve 31 opens and the inside of the high pressure fuel passage The fuel pressure decreases to a fuel pressure lower than the high fuel pressure abnormality determination value.

  The engine is also provided with an air flow meter 32 that detects the intake air amount and a crank angle sensor 33 that outputs a pulse signal each time the crankshaft rotates a predetermined crank angle. Based on the output signal of the crank angle sensor 33, the crank angle and the engine speed are detected.

  Furthermore, a starter 34 for cranking the engine (that is, rotating the crankshaft of the engine) is attached to the engine. By turning ON / OFF the starter relay 35, energization from a battery (not shown) to the starter 34 is turned ON / OFF. That is, when the starter relay 35 is turned on, power is supplied from the battery to the starter 34, and the engine is cranked by the starter 34. Thereafter, when the starter relay 35 is turned off, power supply from the battery to the starter 34 is stopped, and engine cranking by the starter 34 is stopped.

  A starter switch 36 (for example, a push switch or a key switch) for turning on (or turning on / off) the starter relay 35 is provided in the vicinity of the driver's seat of the vehicle. Furthermore, a brake operation (for example, ON / OFF of the brake) is detected by the brake switch 37, and a shift position that is an operation position of the shift lever is detected by the shift switch 38.

  The outputs of the various sensors described above are input to the ECU 39, which is an electronic control unit. The ECU 39 is composed mainly of a microcomputer, and executes various engine control programs stored in a built-in ROM. Thus, the fuel injection amount, the ignition timing, the throttle opening (that is, the intake air amount) and the like are controlled according to the engine operating state.

  At that time, the ECU 39 calculates the target fuel pressure from a map or the like according to the engine operating state (for example, engine speed, engine load, etc.). Then, fuel pressure feedback control is performed to feedback control the discharge amount of the high pressure pump 14 (that is, the energization timing of the fuel pressure control valve 23) so that the actual fuel pressure in the high pressure fuel passage detected by the fuel pressure sensor 29 matches the target fuel pressure.

In the first embodiment, the ECU 39 performs the following start control by executing the routines shown in FIGS. 4 and 5 described later.
As shown in FIG. 3, the starter relay 35 is turned on at a time t1 when a predetermined engine start condition is satisfied. Thereby, the starter 34 is energized to start cranking the engine.

  Thereafter, at the time t2 when the fuel pressure in the high pressure fuel passage becomes equal to or higher than the target fuel pressure, the fuel injection of the fuel injection valve 28 is permitted. Thereby, energization of the fuel injection valve 28 is turned ON at each injection timing, and fuel injection of the fuel injection valve 28 is started.

  Thereafter, the starter relay 35 is turned off at time t3 when the engine speed exceeds the start determination value and the start completion is determined. As a result, the starter 34 is turned off and the cranking of the engine is terminated.

  However, after this, if the fuel pressure in the high pressure fuel passage exceeds the high fuel pressure abnormality determination value (that is, the value corresponding to the upper limit fuel pressure at which the fuel injection valve 28 can inject fuel) due to the abnormality of the high pressure pump 14 or the like, the fuel injection valve 28. The fuel will not be able to be injected and the engine will stop burning.

  Therefore, in the first embodiment, when it is determined that the fuel pressure in the high pressure fuel passage has exceeded the high fuel pressure abnormality determination value within a predetermined period from the engine start completion determination at the time of engine start, at the time t4, the starter relay Turn on 35. As a result, energization of the starter 34 is turned on to restart engine cranking.

  Thereafter, the relief valve 31 is opened at time t5 when the fuel pressure in the high-pressure fuel passage becomes higher than the opening pressure of the relief valve 31. Thereby, a fuel pressure falls to a fuel pressure lower than a high fuel pressure abnormality determination value. At that time, fuel injection of the fuel injection valve 28 is resumed at time t6 when the fuel pressure becomes equal to or lower than the high fuel pressure abnormality determination value.

Thus, even if the fuel pressure in the high-pressure fuel passage exceeds the high fuel pressure abnormality determination value immediately after the engine start completion determination and the fuel injection valve 28 cannot perform fuel injection, the engine cranking and the fuel injection valve 28 Restart the fuel injection and restart the engine quickly.
Hereinafter, the processing content of each routine of FIG.4 and FIG.5 which ECU39 performs in the present Example 1 is demonstrated.

[Starting control routine]
The start control routine shown in FIG. 4 is repeatedly executed at a predetermined cycle during the power-on period of the ECU 39, and serves as a start control unit and a fail safe control unit in the claims.

  When this routine is started, first, at step 101, it is determined whether or not a predetermined time has elapsed since the starter relay 35 is turned off (that is, engine start completion determination). This predetermined time is, for example, the upper limit value of the time during which the fuel pressure in the high pressure fuel passage may exceed the high fuel pressure abnormality determination value if an abnormality occurs in the high pressure pump 14 or the like, or a time slightly longer than that (for example, 2s).

If it is determined in step 101 that a predetermined time or more has elapsed since the starter relay 35 was turned off, the process proceeds to step 102. In step 102, it is determined whether the starter relay 35 is OFF.
If it is determined in step 102 that the starter relay 35 is OFF, the process proceeds to step 103. In step 103, it is determined whether the starter switch 36 is ON.

  If it is determined in step 103 that the starter switch 36 is ON, the process proceeds to step 104. In step 104, it is determined whether or not the brake switch 37 is ON (that is, the brake pedal is depressed).

If it is determined in step 104 that the brake switch 37 is ON, the process proceeds to step 105. In step 105, it is determined whether the shift position is in the P range or the N range. In the case of an MT vehicle, it may be determined whether or not the clutch switch is ON (that is, the clutch pedal is depressed).
If it is determined “No” in any of Steps 103 to 105, the process proceeds to Step 109, and the starter relay 35 is maintained OFF.

  On the other hand, if all the determinations in steps 103 to 105 are “Yes”, it is determined that the engine start condition is satisfied, and the process proceeds to step 106. In step 106, it is determined whether or not the actual fuel pressure in the high-pressure fuel passage detected by the fuel pressure sensor 29 is equal to or lower than the high fuel pressure abnormality determination value.

  If it is determined in step 106 that the actual fuel pressure is equal to or lower than the high fuel pressure abnormality determination value, the process proceeds to step 107. In step 107, it is determined whether or not the engine speed is equal to or less than a start determination value.

If it is determined in step 107 that the engine speed is equal to or less than the start determination value, the process proceeds to step 108. In step 108, the starter relay 35 is turned on. Thereby, the starter 34 is energized to perform cranking of the engine.
Thereafter, when it is determined in step 102 that the starter relay 35 is ON, the process of step 103 is skipped and the process proceeds to step 104.

  Thereafter, when it is determined in step 107 that the engine speed has exceeded the start determination value, it is determined that the engine has been started, and the routine proceeds to step 109. In step 109, the starter relay 35 is turned off. As a result, the starter 34 is turned off and the cranking of the engine is terminated.

Thereafter, if it is determined in step 101 that the starter relay 35 is within a predetermined time after the starter relay 35 is turned off (that is, engine start completion determination), the process proceeds to step 110. In step 110, it is determined whether or not the actual fuel pressure in the high-pressure fuel passage detected by the fuel pressure sensor 29 is equal to or higher than the high fuel pressure abnormality determination value.
When it is determined in step 110 that the actual fuel pressure is lower than the high fuel pressure abnormality determination value, the process proceeds to step 109 and the starter relay 35 is maintained OFF.

  On the other hand, if it is determined in step 110 that the actual fuel pressure is equal to or higher than the high fuel pressure abnormality determination value, the process proceeds to step 106 if “Yes” is determined in steps 104 and 105. If it is determined in step 106 that the actual fuel pressure is higher than the high fuel pressure abnormality determination value, the process proceeds to step 108 and the starter relay 35 is turned on.

  As a result, when it is determined that the fuel pressure in the high pressure fuel passage has exceeded the high fuel pressure abnormality determination value within a predetermined time from the engine start completion determination at the time of engine start, the starter relay 35 is turned on again to crank the engine. To resume. In the first embodiment, processes such as steps 106 and 110 serve as an abnormality determination unit in the claims.

[Injection permission determination routine]
The injection permission determination routine shown in FIG. 5 is repeatedly executed at a predetermined cycle during the power-on period of the ECU 39. When this routine is started, first, at step 201, it is determined whether or not the actual fuel pressure in the high pressure fuel passage detected by the fuel pressure sensor 29 is equal to or higher than the target fuel pressure.

  If it is determined in step 201 that the actual fuel pressure is lower than the target fuel pressure, the process proceeds to step 202 and fuel injection is prohibited. As a result, the energization of the fuel injection valve 28 is maintained in the OFF state. When the relief valve 31 is opened and the fuel pressure becomes lower than the target fuel pressure, fuel injection is not prohibited.

  On the other hand, if it is determined in step 201 that the actual fuel pressure is equal to or higher than the target fuel pressure, the routine proceeds to step 203, where fuel injection is permitted. As a result, the fuel injection valve 28 is energized at each injection timing, and the fuel injection of the fuel injection valve 28 is executed.

  In the first embodiment described above, when it is determined that the fuel pressure in the high pressure fuel passage has exceeded the high fuel pressure abnormality determination value within a predetermined time from the engine start completion determination at the time of engine start, the starter relay 35 is turned on. Restart engine cranking. Furthermore, when the fuel pressure in the high-pressure fuel passage exceeds the high fuel pressure abnormality determination value and becomes higher than the valve opening pressure of the relief valve 31, the relief valve 31 opens and the fuel pressure is higher than the high fuel pressure abnormality determination value. Lowers to lower fuel pressure. At that time, when the fuel pressure becomes equal to or lower than the high fuel pressure abnormality determination value, the fuel injection of the fuel injection valve 28 is resumed.

  Thus, even if the fuel pressure in the high-pressure fuel passage exceeds the high fuel pressure abnormality determination value immediately after the engine start completion determination and the fuel injection valve 28 cannot perform fuel injection, the engine cranking and the fuel injection valve 28 The engine can be restarted quickly by restarting the fuel injection. Moreover, it is not necessary to set the valve opening limit pressure of the fuel injection valve 28 (that is, the upper limit fuel pressure at which fuel can be injected) to be equal to or higher than the maximum fuel pressure when the high fuel pressure is abnormal (for example, the valve opening pressure of the relief valve 31). For this reason, the valve opening limit pressure of the fuel injection valve 28 can be set to a relatively low value, and it is not necessary to take much measures to increase the size of the fuel injection valve 28 and the accompanying heat generation of the ECU 39. As a result, the startability of the engine can be ensured even when the fuel pressure is abnormal while suppressing an increase in the cost of the fuel injection valve 28 and the ECU 39 and a deterioration in mountability.

  Next, Embodiment 2 of the present invention will be described with reference to FIGS. However, parts that are substantially the same as or similar to those of the first embodiment are denoted by the same reference numerals, description thereof is omitted or simplified, and parts different from those of the first embodiment are mainly described.

  In the second embodiment, instead of the routine of FIG. 5 described in the first embodiment, a routine of FIG. Thereby, as shown in FIG. 6, the fuel injection of the fuel injection valve 28 is prohibited during the period A in which the fuel pressure in the high-pressure fuel passage exceeds the high fuel pressure abnormality determination value.

Hereinafter, processing contents of the routine of FIG. 7 executed by the ECU 39 in the second embodiment will be described.
In the injection permission determination routine shown in FIG. 7, first, in step 301, it is determined whether or not the actual fuel pressure in the high-pressure fuel passage detected by the fuel pressure sensor 29 is equal to or higher than the target fuel pressure.

  If it is determined in step 301 that the actual fuel pressure is lower than the target fuel pressure, the process proceeds to step 303 and fuel injection is prohibited. As a result, the energization of the fuel injection valve 28 is maintained in the OFF state. When the relief valve 31 is opened and the fuel pressure becomes lower than the target fuel pressure, fuel injection is not prohibited.

  On the other hand, if it is determined in step 301 that the actual fuel pressure is equal to or higher than the target fuel pressure, the routine proceeds to step 302. In step 302, it is determined whether or not the actual fuel pressure in the high-pressure fuel passage detected by the fuel pressure sensor 29 is equal to or lower than a high fuel pressure abnormality determination value.

  If it is determined in step 302 that the actual fuel pressure is equal to or lower than the high fuel pressure abnormality determination value, the routine proceeds to step 304, where fuel injection is permitted. As a result, the fuel injection valve 28 is energized at each injection timing, and the fuel injection of the fuel injection valve 28 is executed.

  On the other hand, if it is determined in step 302 that the actual fuel pressure is higher than the high fuel pressure abnormality determination value, the process proceeds to step 303 and fuel injection is prohibited. As a result, the energization of the fuel injection valve 28 is maintained in the OFF state. Thereby, the fuel injection of the fuel injection valve 28 is prohibited during the period when the fuel pressure in the high pressure fuel passage exceeds the high fuel pressure abnormality determination value. In the second embodiment, the processing in steps 302, 303 and the like serve as an injection prohibition control unit in the claims.

  In the second embodiment described above, fuel injection of the fuel injection valve 28 is prohibited during a period in which the fuel pressure in the high pressure fuel passage exceeds the high fuel pressure abnormality determination value. In this way, during the period when the fuel pressure in the high-pressure fuel passage exceeds the high fuel pressure abnormality determination value (that is, the period during which fuel cannot be injected even if the fuel injection valve 28 is energized), the fuel injection is prohibited. It is possible to stop the energization 28, and to suppress wasteful power consumption and heat generation.

  Next, Embodiment 3 of the present invention will be described with reference to FIGS. However, parts that are substantially the same as or similar to those of the first embodiment are denoted by the same reference numerals, description thereof is omitted or simplified, and parts different from those of the first embodiment are mainly described.

In the third embodiment, instead of the routine of FIG. 4 described in the first embodiment, the ECU 39 executes the routines of FIGS. 9 and 10 to be described later, thereby performing the following start control.
As shown in FIG. 8, when it is determined that the fuel pressure in the high pressure fuel passage exceeds the high fuel pressure abnormality determination value during engine operation, the high fuel pressure abnormality experience flag is set to “1” at that time t0. . Thereafter, even if the fuel pressure in the high-pressure fuel passage falls below the high fuel pressure abnormality determination value, the high fuel pressure abnormality experience flag is maintained at “1”.

  Thereafter, at a time t1 when a predetermined engine start condition is satisfied, the starter relay 35 is turned on to start cranking the engine. Thereafter, at the time t2 when the fuel pressure in the high pressure fuel passage becomes equal to or higher than the target fuel pressure, the fuel injection of the fuel injection valve 28 is permitted and the fuel injection of the fuel injection valve 28 is started.

  However, if it is determined that the fuel pressure in the high-pressure fuel passage has exceeded the high fuel pressure abnormality judgment value during the previous engine operation (that is, if the high fuel pressure abnormality experience flag is 1), It can be determined that there is a high possibility that the fuel injection valve 28 will not be able to inject fuel when the internal fuel pressure exceeds the high fuel pressure abnormality determination value.

  Therefore, in the third embodiment, when it is determined that the fuel pressure in the high-pressure fuel passage has exceeded the high fuel pressure abnormality determination value during the previous engine operation, after the engine speed exceeds the start determination value at the time of engine start. Also, the starter relay 35 is maintained ON, and the engine cranking is continued. In this case, the cranking of the engine is continued until a predetermined period elapses from the start of the cranking of the engine, so that the cranking of the engine is continued even after the engine speed exceeds the start determination value.

  Thereafter, when the fuel pressure in the high pressure fuel passage exceeds the high fuel pressure abnormality determination value, fuel injection cannot be performed by the fuel injection valve 28, but when the fuel pressure in the high pressure fuel passage becomes higher than the opening pressure of the relief valve 31. At t5, the relief valve 31 is opened. Thereby, a fuel pressure falls to a fuel pressure lower than a high fuel pressure abnormality determination value. At that time, fuel injection of the fuel injection valve 28 is resumed at time t6 when the fuel pressure becomes equal to or lower than the high fuel pressure abnormality determination value.

Thus, even if the fuel pressure in the high-pressure fuel passage exceeds the high fuel pressure abnormality determination value immediately after the engine rotation speed exceeds the start determination value and fuel injection cannot be performed by the fuel injection valve 28, the engine cranking is performed. The fuel injection of the fuel injection valve 28 is resumed and the engine is restarted promptly.
Hereinafter, processing contents of the routines of FIGS. 9 and 10 executed by the ECU 39 in the third embodiment will be described.

[High fuel pressure abnormality determination routine]
The high fuel pressure abnormality determination routine shown in FIG. 9 is repeatedly executed at a predetermined period during the power-on period of the ECU 39, and serves as an abnormality determination unit in the claims.

When this routine is started, first, in step 401, it is determined whether or not the actual fuel pressure in the high-pressure fuel passage detected by the fuel pressure sensor 29 has exceeded a high fuel pressure abnormality determination value.
If it is determined in step 401 that the actual fuel pressure is equal to or lower than the high fuel pressure abnormality determination value, the routine ends while the high fuel pressure abnormality experience flag is maintained at “0”.

  Thereafter, if it is determined in step 401 that the actual fuel pressure has exceeded the high fuel pressure abnormality determination value, the process proceeds to step 402, and the high fuel pressure abnormality experience flag is set to “1”. Thereafter, even if the fuel pressure in the high-pressure fuel passage falls below the high fuel pressure abnormality determination value, the high fuel pressure abnormality experience flag is maintained at “1”. This high fuel pressure abnormality experience flag is stored in a rewritable nonvolatile memory such as a backup RAM of the ECU 39 (that is, a rewritable memory that holds stored data even when the ECU 39 is powered off).

[Starting control routine]
The start control routine shown in FIG. 10 is repeatedly executed at a predetermined cycle during the power-on period of the ECU 39, and serves as a start control unit and a fail safe control unit in the claims.

When this routine is started, first, at step 501, it is determined whether or not the starter relay 35 is OFF.
If it is determined in step 501 that the starter relay 35 is OFF, the process proceeds to step 502. In step 502, it is determined whether the starter switch 36 is ON.

  If it is determined in step 502 that the starter switch 36 is ON, the process proceeds to step 503. In step 503, it is determined whether or not the brake switch 37 is ON (that is, the brake pedal is depressed).

  If it is determined in step 503 that the brake switch 37 is ON, the process proceeds to step 504. In step 504, it is determined whether the shift position is in the P range or the N range. In the case of an MT vehicle, it may be determined whether or not the clutch switch is ON (that is, the clutch pedal is depressed).

  If “No” is determined in any of Steps 502 to 504, the process proceeds to Step 510. In this step 510, a cranking time counter that counts the cranking time (that is, the elapsed time from the start of cranking) is maintained at “0”. Thereafter, the process proceeds to step 511, and the starter relay 35 is kept OFF.

  On the other hand, if all the determinations in steps 502 to 504 are “Yes”, it is determined that the engine start condition is satisfied, and the process proceeds to step 505. In step 505, it is determined whether or not the high fuel pressure abnormality experience flag is “1”.

  If it is determined in step 505 that the high fuel pressure abnormality experience flag is “0”, the process proceeds to step 506. In this step 506, it is determined whether or not the engine speed is equal to or less than a start determination value.

If it is determined in step 506 that the engine speed is equal to or less than the start determination value, the process proceeds to step 508, and the cranking time counter is counted up. Thereafter, the process proceeds to step 509 and the starter relay 35 is turned ON. Thereby, the starter 34 is energized to perform cranking of the engine.
Thereafter, if it is determined in step 501 that the starter relay 35 is ON, the process of step 502 is skipped and the process proceeds to step 503.

  Thereafter, if it is determined in step 506 that the engine speed has exceeded the start determination value, it is determined that the engine has been started, and the process proceeds to step 510. In step 510, the cranking time counter is reset to “0”. Thereafter, the process proceeds to step 511 and the starter relay 35 is turned off. As a result, the starter 34 is turned off and the cranking of the engine is terminated.

  On the other hand, when the high fuel pressure abnormality experience flag is determined to be “1” in step 505 (that is, it is determined that the fuel pressure in the high pressure fuel passage has exceeded the high fuel pressure abnormality determination value during the previous engine operation). If YES, go to step 507. In step 507, it is determined whether or not the cranking time counted by the cranking time counter is equal to or shorter than a predetermined time. Here, for example, the predetermined time is set to a time sufficient to restart the engine when the fuel pressure exceeds the high fuel pressure abnormality determination value and fuel injection cannot be performed by the fuel injection valve 28.

  If it is determined in step 507 that the cranking time is equal to or shorter than the predetermined time, the process proceeds to step 508 and the cranking time counter is counted up. Thereafter, the process proceeds to step 509 and the starter relay 35 is turned ON. Thereby, the starter 34 is energized to perform cranking of the engine.

  Thereafter, if it is determined in step 507 that the cranking time has exceeded a predetermined time, the process proceeds to step 510. In step 510, the cranking time counter is reset to “0”. Thereafter, the process proceeds to step 511 and the starter relay 35 is turned off. As a result, the starter 34 is turned off and the cranking of the engine is terminated. In this way, the cranking of the engine is continued until a predetermined time has elapsed from the start of the cranking of the engine, so that the cranking of the engine is continued even after the engine speed exceeds the start determination value.

  In the third embodiment described above, when it is determined that the fuel pressure in the high-pressure fuel passage has exceeded the high fuel pressure abnormality determination value during the previous engine operation, the engine speed at the current engine start will be the start determination value. Continue to crank the engine even after it exceeds. Furthermore, when the fuel pressure in the high-pressure fuel passage exceeds the high fuel pressure abnormality determination value and becomes higher than the valve opening pressure of the relief valve 31, the relief valve 31 opens and the fuel pressure is higher than the high fuel pressure abnormality determination value. Lowers to lower fuel pressure. At that time, when the fuel pressure becomes equal to or lower than the high fuel pressure abnormality determination value, the fuel injection of the fuel injection valve 28 is resumed.

  Thus, even if the fuel pressure in the high-pressure fuel passage exceeds the high fuel pressure abnormality determination value immediately after the engine rotation speed exceeds the start determination value and fuel injection cannot be performed by the fuel injection valve 28, the engine cranking is performed. The fuel injection of the fuel injection valve 28 can be resumed and the engine can be restarted quickly. Thereby, substantially the same effect as the first embodiment can be obtained.

  In the third embodiment, the engine cranking is continued until a predetermined time has elapsed from the start of engine cranking, so that the engine cranking is continued even after the engine speed exceeds the start determination value. I have to. In this way, cranking can be terminated when a predetermined time elapses by continuing cranking of the engine even after the engine rotation speed exceeds the start determination value.

  The engine cranking is continued until a predetermined time elapses after the engine speed exceeds the start determination value, so that the engine cranking is continued even after the engine speed exceeds the start determination value. May be.

  Further, instead of the predetermined time, a period until the number of crankings (that is, the number of engine revolutions) reaches a predetermined value, a period until the number of rotations of the starter reaches a predetermined value, or the like may be used.

  Further, cranking of the engine may be continued even after the engine rotation speed exceeds the start determination value, and the cranking may be terminated when the engine rotation speed again exceeds the start determination value.

  Further, in the third embodiment, the routine of FIG. 7 is executed instead of the routine of FIG. 5, and the fuel injection of the fuel injection valve 28 is performed during the period when the fuel pressure in the high pressure fuel passage exceeds the high fuel pressure abnormality determination value. May be prohibited.

  Further, engine cranking may be continued during cranking before engine start completion determination or when it is determined that the fuel pressure in the high pressure fuel passage has exceeded the high fuel pressure abnormality determination value immediately after the ECU is started. good.

Further, in each of the first to third embodiments, some or all of the functions executed by the ECU 39 may be configured by hardware using one or a plurality of ICs.
In addition, the present invention can be implemented with various modifications without departing from the gist, such as appropriately changing the configuration of the high-pressure pump and the configuration of the fuel supply system.

  DESCRIPTION OF SYMBOLS 12 ... Low pressure pump, 13 ... Low pressure fuel piping, 14 ... High pressure pump, 26 ... High pressure fuel piping, 27 ... Delivery pipe, 28 ... Fuel injection valve, 30 ... Fuel return passage, 31 ... Relief valve, 39 ... ECU

Claims (4)

A low pressure fuel passage (13) for supplying fuel discharged from the low pressure pump (12) to the high pressure pump (14), and a high pressure fuel for supplying fuel discharged from the high pressure pump to the fuel injection valve (28) of the internal combustion engine A passage (26, 27) and a start control unit (39) for ending cranking of the internal combustion engine when the internal combustion engine is started and the rotational speed of the internal combustion engine exceeds a start determination value and the start completion is determined. In the internal combustion engine start control device provided,
An abnormality determination unit (39) for determining whether or not a fuel pressure in the high pressure fuel passage (hereinafter referred to as “fuel pressure”) exceeds a high fuel pressure abnormality determination value corresponding to an upper limit fuel pressure at which the fuel injection valve can inject fuel; ,
A fuel return passage (30) for returning the fuel in the high-pressure fuel passage to the low-pressure fuel passage is provided, and the fuel pressure in the high-pressure fuel passage is set to a valve opening pressure that is set to a higher pressure side than the high fuel pressure abnormality determination value. The relief valve (31) that opens when the fuel pressure becomes higher and closes when the fuel pressure in the high-pressure fuel passage becomes lower than the valve-closing pressure set to the low-pressure side than the high fuel pressure abnormality determination value. When,
When the internal combustion engine is started, if it is determined that the fuel pressure in the high pressure fuel passage has exceeded the high fuel pressure abnormality determination value within a predetermined period from the start completion determination of the internal combustion engine, cranking of the internal combustion engine is resumed. A start control device for an internal combustion engine, comprising: a fail-safe control unit (39).   The internal combustion engine according to claim 1, further comprising an injection prohibition control unit (39) for prohibiting fuel injection of the fuel injection valve during a period in which the fuel pressure in the high-pressure fuel passage exceeds the high fuel pressure abnormality determination value. Start control device. A low pressure fuel passage (13) for supplying fuel discharged from the low pressure pump (12) to the high pressure pump (14), and a high pressure fuel for supplying fuel discharged from the high pressure pump to the fuel injection valve (28) of the internal combustion engine A passage (26, 27) and a start control unit (39) for ending cranking of the internal combustion engine when the internal combustion engine is started and the rotational speed of the internal combustion engine exceeds a start determination value and the start completion is determined. In the internal combustion engine start control device provided,
An abnormality determination unit (39) for determining whether or not a fuel pressure in the high pressure fuel passage (hereinafter referred to as “fuel pressure”) exceeds a high fuel pressure abnormality determination value corresponding to an upper limit fuel pressure at which the fuel injection valve can inject fuel; ,
A fuel return passage (30) for returning the fuel in the high-pressure fuel passage to the low-pressure fuel passage is provided, and the fuel pressure in the high-pressure fuel passage is set to a valve opening pressure that is set to a higher pressure side than the high fuel pressure abnormality determination value. The relief valve (31) that opens when the fuel pressure becomes higher and closes when the fuel pressure in the high-pressure fuel passage becomes lower than the valve-closing pressure set to the low-pressure side than the high fuel pressure abnormality determination value. When,
If it is determined that the fuel pressure in the high pressure fuel passage has exceeded the high fuel pressure abnormality determination value during the previous operation of the internal combustion engine, the rotational speed of the internal combustion engine is determined to be the start determination value when the internal combustion engine is started. And a fail-safe control unit (39) for continuing the cranking of the internal combustion engine even after exceeding the limit.   The fail-safe control unit performs cranking of the internal combustion engine until a predetermined period elapses from the start of cranking of the internal combustion engine or until a predetermined period elapses after the rotation speed of the internal combustion engine exceeds the start determination value. The start control device for an internal combustion engine according to claim 3, wherein the cranking of the internal combustion engine is continued even after the rotation speed of the internal combustion engine exceeds the start determination value by continuing.

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