Vehicle control method and vehicle control device

Abstract

In vehicles equipped with an internal combustion engine that has a device, the control system is improved by utilizing the results of fault diagnosis of the sensor that detects the output value of the device. [Solution] The control unit 31 performs a primary fail-safe (F / S) that imposes a predetermined restriction on the operation of the fuel supply device 3 if the detected value of the fuel pressure sensor 8 falls outside a predetermined judgment range. The control unit 31 performs a fault diagnosis of the fuel pressure sensor 8 during the primary F / S. If the control unit 31 determines that the sensor has failed, or if the cumulative value of the primary fail-safe execution time during one trip exceeds the cumulative time threshold, it performs a secondary fail-safe (F / S) that limits the output of the internal combustion engine 2 so that the fuel supply device 3, whose operation has been restricted, can respond to the operation request of the internal combustion engine 2.

Description

Technical Field

[0001] The present invention relates to a vehicle control method and a vehicle control device.

Background Art

[0002] For example, Patent Document 1 discloses a high-pressure fuel supply device for an internal combustion engine, which includes a high-pressure pump that supplies high-pressure fuel pressurized to an injector, a low-pressure pump that pumps up fuel in a fuel tank and supplies it to the high-pressure pump, and a fuel pressure sensor that detects the pressure of the fuel supplied to the injector.

[0003] In the high-pressure fuel supply device of Patent Document 1, if the output voltage from the fuel pressure sensor is not within a predetermined range, it is determined that there is an abnormality in the fuel pressure sensor and the high-pressure pump is stopped. Further, in Patent Document 1, if the output voltage of the fuel pressure sensor is within the predetermined range, it is determined that the fuel pressure sensor is functioning normally, and if it is not within the predetermined range, it is determined that there is an abnormality in the fuel pressure sensor.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in such Patent Document 1, when the output voltage of the fuel pressure sensor repeatedly alternates between a value within a predetermined range and a value outside the predetermined range in a short period of time, that is, when the output voltage of the fuel pressure sensor repeatedly experiences momentary voltage drops (instantaneous lows), it cannot be determined whether the fuel pressure sensor is normal or faulty. Therefore, in Patent Document 1, if the output voltage of the fuel pressure sensor continues to experience instantaneous lows, there is a risk of causing misfires in the internal combustion engine due to abnormal combustion caused by a lean air-fuel ratio and adverse effects on the exhaust catalyst.

[0006] In other words, in vehicles equipped with internal combustion engines that have devices such as high-pressure fuel supply systems, there is room for further improvement in control systems that utilize the results of fault diagnosis of sensors that detect the output value of devices such as fuel pressure. [Means for solving the problem]

[0007] The vehicle of the present invention is equipped with an internal combustion engine having a device, and if the output value of the device detected by a sensor falls outside a predetermined determination range, a primary fail-safe is implemented to restrict the operation of the device, and during the implementation of the primary fail-safe, a diagnosis is performed to determine whether the sensor is faulty based on the duration that the detected value of the sensor is outside or inside the determination range, and if the sensor is determined to be faulty after the fault diagnosis is performed, or if the cumulative value of the execution time of the primary fail-safe exceeds a predetermined cumulative time threshold, a secondary fail-safe is implemented to restrict the output of the internal combustion engine. [Effects of the Invention]

[0008] The vehicle of the present invention can avoid various risks, such as abnormal combustion of the internal combustion engine, that may occur due to prolonged operation with the device's operation restricted. [Brief explanation of the drawing]

[0009] [Figure 1] A schematic diagram illustrating the general outline of a fuel supply system for an internal combustion engine mounted on a vehicle according to the present invention. [Figure 2] A timing chart showing changes in various parameters of a vehicle during operation according to the present invention. [Figure 3] A timing chart showing changes in various parameters of a vehicle during operation according to the present invention. [Modes for carrying out the invention]

[0010] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

[0011] Figure 1 is a schematic diagram illustrating the general structure of the fuel supply system 3 for the internal combustion engine 2 mounted on vehicle 1.

[0012] The internal combustion engine 2 is a direct-injection, spark-ignition internal combustion engine mounted in a vehicle 1, such as an automobile.

[0013] The fuel supply device 3 is a device of the internal combustion engine 2 and includes a low-pressure fuel pump 4, a high-pressure fuel pump 5, a pressure accumulator 7 that supplies high-pressure fuel to the fuel injection valves 6 of each cylinder, and a fuel pressure sensor (pressure sensor) 8, and is controlled by a control unit 31.

[0014] The low-pressure fuel pump 4 is equivalent to a low-pressure pump and is driven by the motor 11. The low-pressure fuel pump 4 supplies the fuel from the fuel tank 12 to the high-pressure fuel pump 5 in the required amount and at a predetermined pressure (feed pressure). The low-pressure fuel pump 4 supplies the fuel from the fuel tank 12 to the high-pressure fuel pump 5 via a low-pressure fuel passage 14 to which a fuel damper 13 is attached.

[0015] The motor 11 is controlled by the control unit 31. The fuel damper 13 suppresses fluctuations in fuel pressure. In addition, a low-pressure pressure regulator 15 is provided on the discharge side of the low-pressure fuel pump 4, which adjusts the pressure in the low-pressure fuel passage 14 to a predetermined constant pressure by returning excess fuel to the fuel tank 12. The low-pressure pressure regulator 15 is attached to the low-pressure fuel passage 14, and is mounted in the low-pressure fuel passage 14 at a position closer to the low-pressure fuel pump 4 than the fuel damper 13.

[0016] The high-pressure fuel pump 5 is equivalent to a high-pressure pump and is driven by the rotation of a cam 16 connected to the camshaft of the internal combustion engine 2. The high-pressure fuel pump 5 supplies high-pressure fuel, which has been pressurized to a predetermined high pressure, to the accumulator chamber 7 via the high-pressure fuel passage 17. More specifically, the high-pressure fuel pump 5 controls the pressure of the high-pressure fuel based on the actual fuel pressure detected by, for example, the fuel pressure sensor 8 (described later), so that the fuel supplied from the fuel tank 12 can be controlled to a target fuel pressure, and pumps the required amount of high-pressure fuel to the accumulator chamber 7.

[0017] The high-pressure fuel pump 5 is a so-called plunger pump, which pressurizes the fuel supplied to the pump chamber 20 by changing the volume of the pump chamber 20 by reciprocating the plunger 18 against the spring force of the spring 19. Fuel is supplied to the pump chamber 20 via the first check valve 21 during the intake stroke when the plunger 18 descends from top dead center. High-pressure fuel is discharged from the pump chamber 20 to the high-pressure fuel passage 17 via the second check valve 22 during the discharge stroke when the plunger 18 rises from bottom dead center. The first check valve 21 is a one-way valve that allows fuel to flow from the low-pressure fuel passage 14 to the pump chamber 20. The second check valve 22 is a one-way valve that allows fuel to flow from the pump chamber 20 to the high-pressure fuel passage 17.

[0018] Furthermore, the high-pressure fuel pump 5 has a solenoid 23 on the opposite side of the pump chamber 20 from the first check valve 21, whose energization is controlled by the control unit 31. The solenoid 23 generates an electromagnetic force when energized, which allows it to hold the first check valve 21 open regardless of the pressure in the pump chamber 20. Therefore, the control unit 31 can control the discharge amount of the high-pressure fuel pump 5 by ending the energization of the solenoid 23 at any timing during the discharge stroke.

[0019] Furthermore, the high-pressure fuel pump 5 has a return passage 24 that branches off from the high-pressure fuel passage 17 between the second check valve 22 and the accumulator chamber 7. The return passage 24 is provided with a third check valve 25 on the passage, and it is possible to return the high-pressure fuel to the upstream side of the pump chamber 20. The third check valve 25 is a one-way valve that allows the flow of fuel from the high-pressure fuel passage 17 side toward the downstream side of the pump chamber 20. Thereby, when the pressure in the high-pressure fuel passage 17 exceeds a preset allowable pressure, the third check valve 25 opens and part of the fuel is returned, preventing the fuel pressure in the accumulator chamber 7 from becoming excessively high.

[0020] The accumulator chamber 7 distributes the fuel pumped from the high-pressure fuel pump 5 to the fuel injection valves 6 of each cylinder. The fuel injection valve 6 injects the distributed fuel into the combustion chamber of the internal combustion engine 2 by a required amount at a predetermined timing.

[0021] The fuel pressure sensor 8 detects the fuel pressure in the accumulator chamber 7, which is the output value of the fuel supply device 3, and is attached to the accumulator chamber 7. That is, the detected value of the fuel pressure sensor 8 is, in other words, the output value of the fuel supply device 3. The detection signal of the fuel pressure sensor 8 is input to the control unit 31 as the control unit.

[0022] The control unit 31 is a well-known digital computer equipped with a CPU, ROM, RAM, and an input / output interface. The control unit 31 optimally controls the fuel injection amount, fuel injection timing, ignition timing of the internal combustion engine 2, intake air amount, etc. of the internal combustion engine 2 based on the detection signals of various sensors and the like. Further, the control unit 31 controls so that the fuel pressure of the fuel supplied from the fuel supply device 3 to the fuel injection valves 6 of each cylinder becomes a predetermined target pressure.

[0023] Furthermore, when the detection value of the fuel pressure sensor 8 deviates from a predetermined determination range set so as to include the target pressure, the control unit 31 as a control section performs a primary fail-safe (primary F / S) that gives a predetermined restriction to the operation of the fuel supply device 3. The determination range is defined by a predetermined output upper limit value and an output lower limit value set so as to include the target pressure, and is a range sandwiched between the output upper limit value and the output lower limit value. As an operation restriction by the primary fail-safe, the high-pressure fuel pump 5 stops in the fuel supply device 3. That is, when the primary fail-safe is implemented in the fuel supply device 3, fuel at a predetermined pressure (feed pressure) from the low-pressure fuel pump 4 is supplied to the accumulator chamber 7.

[0024] During the implementation of the primary fail-safe, the control unit 31 performs a diagnosis (fault diagnosis) to determine whether the fuel pressure sensor 8 has failed based on the time during which the detection value of the fuel pressure sensor 8 exists inside (within) the determination range and the time during which the detection value of the fuel pressure sensor 8 exists outside (outside) the determination range.

[0025] During the execution of the primary fail-safe, when the detection value of the fuel pressure sensor 8 continues (is continuous) within the determination range for a predetermined fault determination time (for example, 5 seconds), the control unit 31 determines that the fuel pressure sensor 8 is normal, ends the primary fail-safe, and returns to normal control. When the detection value of the fuel pressure sensor 8 continues (is continuous) outside the determination range for the fault determination time (for example, 5 seconds), the control unit 31 determines that the fuel pressure sensor 8 has failed.

[0026] In addition, when the integrated value of the execution time of the primary fail-safe during one trip becomes longer than the fault determination time and is equal to or longer than a predetermined time (integration time threshold value), the control unit 31 determines that the fuel pressure sensor 8 has failed even if the detection value of the fuel pressure sensor 8 does not continuously stay outside the determination range for the fault determination time. Here, the trip in this specification refers to the period from when the ignition switch of the vehicle 1 is turned on until it is turned off.

[0027] Furthermore, if the control unit 31 determines that the fuel pressure sensor 8 has failed as a result of fault diagnosis, or if the cumulative value of the execution time of the primary failsafe exceeds a predetermined cumulative time threshold set in advance, the control unit 31 implements a secondary failsafe (secondary F / S) that limits the output of the internal combustion engine 2 so that the fuel supply device 3, whose operation is restricted, can respond to the operating request of the internal combustion engine 2.

[0028] Figure 2 is a timing chart showing the changes in various parameters of the vehicle 1 of the above-described embodiment while it is in motion, and is a timing chart showing an example of when the count value of the NG counter (described later) reaches the NG count threshold while in motion.

[0029] Time t1 in Figure 2 is the moment when the ignition switch is turned on by the driver of vehicle 1 and the internal combustion engine 2 starts.

[0030] In Figure 2, the value detected by the fuel pressure sensor 8 is outside the above-mentioned judgment range from time t1. Therefore, in the example in Figure 2, the primary failsafe flag becomes "1" from time t1, and primary failsafe is implemented from time t1. Primary failsafe is implemented when the primary failsafe flag is "1".

[0031] The NG counter is a counter that accumulates the execution time of the primary failsafe, and the counting starts from time t1. The NG counter is equivalent to a counter, and is a function provided by, for example, the control unit 31.

[0032] The NG counter measures the execution time of primary failsafes that occur repeatedly during a single trip from when the ignition switch of vehicle 1 is turned on until it is turned off. It accumulates the execution time of primary failsafes that occur repeatedly during a single trip. In other words, the NG counter continues to accumulate the execution time of primary failsafes during a single trip without resetting it. The count value of the NG counter is the accumulated value of the execution time of primary failsafes that were performed during a single trip.

[0033] The control unit 31 determines that there is an abnormality in the fuel pressure sensor 8 if the NG counter's count value exceeds a predetermined NG count threshold during one trip, and sets the OK / NG judgment flag to "1". The NG count threshold corresponds to the cumulative time threshold. The OK / NG judgment flag is reset (to "0") at the end of one trip. Then, for example, if the OK / NG judgment flag is "1" for two consecutive trips without any "2" in between, the control unit 31 illuminates the warning light for the fuel pressure sensor located in the passenger compartment of vehicle 1. This warning light corresponds to a notification device. Illuminating the warning light is equivalent to activating the notification device. The control unit 31 also remembers if the OK / NG judgment flag has been "1" or "2" in past trips.

[0034] Time t2 in Figure 2 is the moment when the value detected by the fuel pressure sensor 8 falls within the above judgment range, the primary failsafe flag becomes "0", and the OK counter starts counting. The NG counter stops counting at time t2 in Figure 2.

[0035] The OK counter starts counting when the value detected by the fuel pressure sensor 8 is within the above-mentioned judgment range while the primary and secondary fail-safes are not being executed. The OK counter stops counting when the primary fail-safe is executed during counting. In other words, the OK counter measures the time when the primary fail-safe is not being executed. Also, when the primary fail-safe is executed, the OK counter resets the measured value (count value) that has been measured (counted) up to that point (to "0"). The OK counter is a function provided by, for example, the control unit 31.

[0036] The control unit 31 determines that the fuel pressure sensor 8 is functioning normally and sets the OK / NG judgment flag to "2" if the OK counter count value exceeds a predetermined OK count threshold during one trip. At this point, if the fuel pressure sensor warning light is illuminated and, for example, the OK / NG judgment flag becomes "2" for three consecutive trips without any "1" in between, the control unit 31 turns off the illuminated fuel pressure sensor warning light.

[0037] At time t3 in Figure 2, the value detected by the fuel pressure sensor 8 falls outside the above-mentioned judgment range, and the primary failsafe flag becomes "1". Therefore, the primary failsafe is performed again from time t3. The NG counter also restarts counting from time t3. The OK counter is reset at time t3.

[0038] At time t4 in Figure 2, the value detected by the fuel pressure sensor 8 falls within the above-mentioned judgment range, the primary failsafe flag becomes "0", and the OK counter begins counting. The NG counter stops counting at time t4.

[0039] At time t5 in Figure 2, the value detected by the fuel pressure sensor 8 falls outside the above-mentioned judgment range, and the primary failsafe flag becomes "1". Therefore, the primary failsafe is performed again from time t5. The NG counter also restarts counting from time t5. The OK counter is reset at time t5.

[0040] Time t6 in Figure 2 is the moment when the NG counter's count value reaches the NG count threshold. Vehicle 1 performs a secondary failsafe from time t6, when the NG counter's count value reaches the NG count threshold and the OK / NG judgment flag becomes "1".

[0041] In Figure 2, time t7 represents the moment when the ignition switch is turned off and the operation of vehicle 1 ends. The OK / NG judgment flag is reset at time t7. Also, the secondary failsafe is terminated at time t7.

[0042] When the ignition switch is turned off, the primary failsafe flag, NG counter, and OK counter are reset. Also, when the ignition switch is turned off, the primary and secondary failsafes, if in progress, are terminated. In Figure 2, for convenience, the trip of vehicle 1 during the period from time t1 to t7 is referred to as the first trip.

[0043] Time t8 in Figure 2 is the timing when the ignition switch is turned on by the driver of vehicle 1 after the end of the first trip, and the internal combustion engine 2 starts.

[0044] In Figure 2, the value detected by the fuel pressure sensor 8 is outside the above-mentioned judgment range from time t8. Therefore, in the example in Figure 2, the primary failsafe flag becomes "1" from time t8, and primary failsafe is implemented from time t8.

[0045] At time t9 in Figure 2, the value detected by the fuel pressure sensor 8 falls within the above-mentioned judgment range, the primary failsafe flag becomes "0", and the OK counter begins counting. The NG counter stops counting at time t9 in Figure 2.

[0046] At time t10 in Figure 2, the detected value from the fuel pressure sensor 8 falls outside the above-mentioned judgment range, and the primary failsafe flag becomes "1". Therefore, the primary failsafe is performed again from time t10. The NG counter also restarts counting from time t10. The OK counter is reset at time t10.

[0047] At time t11 in Figure 2, the value detected by the fuel pressure sensor 8 falls within the above-mentioned judgment range, the primary failsafe flag becomes "0", and the OK counter begins counting. The NG counter stops counting at time t11.

[0048] At time t12 in Figure 2, the detected value from the fuel pressure sensor 8 falls outside the above-mentioned judgment range, and the primary failsafe flag becomes "1". Therefore, the primary failsafe is performed again from time t12. The NG counter also restarts counting from time t12. The OK counter is reset at time t12.

[0049] In Figure 2, time t13 is the moment when the NG counter's count value reaches the NG count threshold. Vehicle 1 performs a secondary failsafe from time t6, when the NG counter's count value reaches the NG count threshold and the OK / NG judgment flag becomes "1".

[0050] In this case, if the secondary failsafe was not performed during the trip immediately preceding the first trip in Figure 2, the OK / NG judgment flag will be "1" consecutively during two consecutive trips at time t13, without any "2" in between. Therefore, if the secondary failsafe was not performed during the trip immediately preceding the first trip in Figure 2, the warning light for the fuel pressure sensor located inside the passenger compartment of vehicle 1 will illuminate at time t13.

[0051] In Figure 2, time t14 is when the ignition switch is turned off and the operation of vehicle 1 ends. The OK / NG judgment flag is reset at time t14. Also, the secondary failsafe is terminated at time t14.

[0052] In Figure 2, for convenience, the trip of vehicle 1 during the period from time t8 to t17 is referred to as the second trip.

[0053] Figure 3 is a timing chart showing the changes in various parameters of the vehicle 1 of the above-described embodiment while it is in motion, and is a timing chart showing an example where the count value of the OK counter reaches the OK count threshold while in motion.

[0054] Time t1 in Figure 3 is the moment when the ignition switch of vehicle 1 is turned on by the driver and the internal combustion engine 2 starts.

[0055] In Figure 3, the value detected by the fuel pressure sensor 8 is outside the above-mentioned judgment range from time t1. Therefore, in the example in Figure 3, the primary failsafe flag becomes "1" from time t1, and primary failsafe is implemented from time t1.

[0056] At time t2 in Figure 3, the value detected by the fuel pressure sensor 8 falls within the above-mentioned judgment range, the primary failsafe flag becomes "0", and the OK counter begins counting. The NG counter stops counting at time t2 in Figure 3.

[0057] At time t3 in Figure 3, the detected value from the fuel pressure sensor 8 falls outside the above-mentioned judgment range, and the primary failsafe flag becomes "1". Therefore, the primary failsafe is performed again from time t3. The NG counter also restarts counting from time t3. The OK counter is reset at time t3.

[0058] At time t4 in Figure 3, the value detected by the fuel pressure sensor 8 falls within the above-mentioned judgment range, the primary failsafe flag becomes "0", and the OK counter begins counting. The NG counter stops counting at time t4.

[0059] At time t5 in Figure 3, the value detected by the fuel pressure sensor 8 falls outside the above-mentioned judgment range, and the primary failsafe flag becomes "1". Therefore, the primary failsafe is performed again from time t5. The NG counter also restarts counting from time t5. The OK counter is reset at time t5.

[0060] Time t6 in Figure 3 is the moment when the NG counter's count value reaches the NG count threshold. Vehicle 1 performs a secondary failsafe from time t6, when the NG counter's count value reaches the NG count threshold and the OK / NG judgment flag becomes "1".

[0061] In Figure 3, time t7 represents the moment when the ignition switch is turned off and the operation of vehicle 1 ends. The OK / NG judgment flag is reset at time t7. Also, the secondary failsafe is terminated at time t7. In Figure 3, for convenience, the trip of vehicle 1 during the period from time t1 to t7 is referred to as the first trip.

[0062] In Figure 3, a secondary fail-safe is executed immediately before the first trip. Therefore, in Figure 3, the warning light for the fuel pressure sensor located inside the vehicle 1's cabin is illuminated at time t6.

[0063] Time t8 in Figure 3 is the timing when the ignition switch is turned on by the driver of vehicle 1 after the end of the first trip, and the internal combustion engine 2 starts.

[0064] In Figure 3, the value detected by the fuel pressure sensor 8 is outside the above-mentioned judgment range from time t8. Therefore, in the example in Figure 3, the primary failsafe flag becomes "1" from time t8, and primary failsafe is implemented from time t8.

[0065] At time t9 in Figure 3, the value detected by the fuel pressure sensor 8 falls within the above-mentioned judgment range, the primary failsafe flag becomes "0", and the OK counter begins counting. The NG counter stops counting at time t9 in Figure 3.

[0066] In Figure 3, time t10 is the moment when the OK counter's count value reaches the OK count threshold. The OK / NG judgment flag becomes "2" at time t10.

[0067] In Figure 3, time t11 is when the ignition switch is turned off and the operation of vehicle 1 ends. The OK / NG judgment flag is reset at time t11. In Figure 3, for convenience, the trip of vehicle 1 during the period from time t8 to t11 is referred to as the second trip.

[0068] The time t12 in Figure 3 is the moment when the ignition switch is turned on by the driver of vehicle 1 after the end of the second trip, and the internal combustion engine 2 starts.

[0069] In Figure 3, the value detected by the fuel pressure sensor 8 is within the above-mentioned judgment range from time t12. Therefore, in the example in Figure 3, the OK counter starts counting from time t12.

[0070] In Figure 3, time t13 is the moment when the OK counter's count value reaches the OK count threshold. The OK / NG judgment flag becomes "2" at time t13.

[0071] In Figure 3, time t14 is when the ignition switch is turned off and the operation of vehicle 1 ends. The OK / NG judgment flag is reset at time t14. In Figure 3, for convenience, the trip of vehicle 1 during the period from time t12 to t14 is referred to as the third trip.

[0072] In Figure 3, time t15 is the moment when the ignition switch is turned on by the driver of vehicle 1 after the end of the third trip, and the internal combustion engine 2 starts.

[0073] In Figure 3, the value detected by the fuel pressure sensor 8 falls within the above-mentioned judgment range from time t15. Therefore, in the example in Figure 3, the OK counter starts counting from time t15.

[0074] In Figure 3, time t16 is the moment when the OK counter's count value reaches the OK count threshold. The OK / NG judgment flag becomes "2" at time t15. Here, time t16 in Figure 3 is the moment when the OK / NG judgment flag becomes "2" consecutively for three consecutive trips without any "1" in between. Therefore, at time t16 in Figure 3, the warning light for the fuel pressure sensor located inside the vehicle 1's cabin is turned off.

[0075] In Figure 3, time t17 is when the ignition switch is turned off and the operation of vehicle 1 ends. The OK / NG judgment flag is reset at time t17. In Figure 3, for convenience, the trip of vehicle 1 during the period from time t15 to t17 is referred to as the fourth trip.

[0076] Note that the time t18 in Figure 3 is the moment when the ignition switch is turned on by the driver of vehicle 1 after the end of the fourth trip, and the internal combustion engine 2 starts.

[0077] If the fuel pressure sensor 8 repeatedly switches between normal and abnormal values ​​(for example, a momentary voltage drop) in a short period of time, it becomes impossible to diagnose whether the fuel pressure sensor 8 is functioning normally or abnormally. In other words, when diagnosing a fault in the fuel pressure sensor 8 during primary failsafe operation, if the output of the fuel pressure sensor 8 repeatedly switches between normal and abnormal values ​​in a short period of time, it may not be possible to return to normal operation or to diagnose an abnormality and proceed to secondary failsafe operation, potentially causing primary failsafe operation to continue for an extended period.

[0078] However, in the above-described embodiment, vehicle 1 will transition to secondary failsafe mode if it is determined that the fuel pressure sensor 8 has failed, or if the cumulative value of the primary failsafe execution time exceeds the cumulative time threshold.

[0079] As a result, the vehicle 1 in the above-described embodiment can prevent the primary fail-safe from lasting for an extended period. Therefore, the vehicle 1 can avoid misfires or adverse effects on the catalytic converter caused by abnormal combustion resulting from a lean air-fuel ratio in the internal combustion engine 2 due to insufficient fuel pressure.

[0080] Furthermore, if Vehicle 1 experiences multiple (two) consecutive trips that result in a secondary fail-safe, it will illuminate a warning light to alert the occupants of Vehicle 1 of the abnormality. This allows Vehicle 1 to notify the driver of an abnormality if the fuel supply system 3 is determined to be abnormal for consecutive trips.

[0081] Vehicle 1 will turn off the warning light if, after the warning light illuminates, multiple (three) consecutive trips occur that do not lead to a secondary fail-safe. This allows Vehicle 1 to turn off the illuminated warning light if the fuel pressure sensor 8 malfunction is temporary or a misdiagnosis, thus avoiding unnecessary repairs.

[0082] Although specific embodiments of the present invention have been described above, the present invention is not limited to the embodiments described above, and various modifications are possible without departing from the spirit of the invention.

[0083] For example, the present invention can also be applied to a system in which a device in an internal combustion engine 2 is used as an intake system, and a sensor that outputs the output value of the intake system is used as an airflow meter. In this case, the intake system is equipped with a variable valve timing mechanism that can change the valve timing of the intake valve or exhaust valve, which are the engine valves of the internal combustion engine 2. More specifically, the variable valve timing mechanism is a phase-variable mechanism that continuously delays the phase of the lift center angle of the engine valve. In this case, the primary fail-safe is the fixing of the variable valve timing mechanism, and the secondary fail-safe is the output limiting of the internal combustion engine 2.

[0084] The embodiments described above relate to a vehicle control method and a vehicle control device. [Explanation of Symbols]

[0085] 1…Vehicle 2…Internal combustion engine 3…Fuel supply device 4. Low-pressure fuel pump 5…High-pressure fuel pump 6…Fuel injector 7…Accumulation chamber 8…Fuel pressure sensor 11…motor 12…Fuel tank 13…Fuel damper 14... Low-pressure fuel passage 15... Low-voltage pressure regulator 16...Come 17…High-pressure fuel passage 18…Plunger 19... Spring 20... Pump Room 21...First check valve 22... Second check valve 23... Solenoid 24…Return aisle 25...Third check valve 31…Control Unit

Claims

1. A control method for a vehicle equipped with an internal combustion engine having a device, If the output value of the above device detected by the sensor falls outside a predetermined judgment range, a primary fail-safe is implemented to restrict the operation of the above device. During the implementation of the above-mentioned primary failsafe, a diagnosis is performed to determine whether the sensor is faulty or not based on the duration that the detected value of the sensor is outside or inside the above-mentioned determination range. A vehicle control method characterized in that, if the above sensor is determined to be faulty, or if the cumulative value of the execution time of the primary fail-safe exceeds a predetermined cumulative time threshold, a secondary fail-safe is implemented that limits the output of the internal combustion engine so that the device whose operation is restricted can respond to the operation request of the internal combustion engine.

2. The vehicle control method according to claim 1, characterized in that the above cumulative value is the cumulative execution time of the primary failsafe that occurred repeatedly during the trip from when the vehicle's ignition switch was turned on until it was turned off.

3. The vehicle control method according to claim 2, characterized in that the above device is a fuel supply device that supplies fuel to the fuel injection valve of the above internal combustion engine, and the above sensor is a fuel pressure sensor that detects the pressure of the fuel supplied to the fuel injection valve.

4. The fuel supply device includes a high-pressure pump capable of controlling the fuel supplied to the fuel injection valve to a predetermined target fuel pressure, and a low-pressure pump that supplies fuel from the fuel tank to the high-pressure pump at a predetermined feed pressure. The vehicle control method according to claim 3, characterized in that the primary fail-safe is the stopping of the high-pressure pump.

5. The vehicle control method according to claim 4, characterized in that the above-mentioned secondary fail-safe is an output limit of the internal combustion engine when the above-mentioned high-pressure pump is stopped.

6. The vehicle control method according to claim 3, characterized in that if the above-mentioned secondary failsafe trip occurs multiple times in a row, a predetermined notification device is activated to inform the occupants of the vehicle of the abnormality.

7. The vehicle control method according to claim 6, characterized in that if multiple trips occur consecutively after the activation of the above-mentioned notification device that do not lead to the above-mentioned secondary failsafe, the operation of the above-mentioned notification device is stopped.

8. A control device for a vehicle equipped with an internal combustion engine having a device, The system includes a control unit that performs a primary fail-safe by restricting the operation of the device if the output value of the device detected by the sensor falls outside a predetermined judgment range. The above control unit, During the implementation of the above-mentioned primary failsafe, a diagnosis is performed to determine whether the sensor is faulty or not based on the duration that the detected value of the sensor is outside or inside the above-mentioned determination range. A vehicle control device characterized in that, if the above-mentioned sensor is determined to be faulty, or if the cumulative value of the execution time of the primary fail-safe exceeds a predetermined cumulative time threshold, a secondary fail-safe is implemented that limits the output of the internal combustion engine so that the device whose operation is restricted can respond to the operation request of the internal combustion engine.

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