Fuel pressure sensor diagnostic device

Abstract

The present invention provides a fuel pressure sensor abnormality diagnosis device that can suppress false detection of abnormalities in the fuel pressure sensor. [Solution] The fuel pressure sensor diagnostic device relates to a vehicle that switches between a drivable state, in which the vehicle can be driven by at least one of the engine and motor, and a non-drivable state, in which the vehicle cannot be driven, in response to the operator's operation, and performs abnormality diagnosis of a fuel pressure sensor that detects the pressure of fuel in the fuel supply passage connected to the engine's fuel injection device. The device includes an estimation unit that estimates the temperature of the fuel in the fuel supply passage when the engine is stopped, a diagnostic unit that performs abnormality diagnosis when the temperature is above a threshold, and a predetermined period of time has elapsed since the vehicle switched from a drivable state to a non-drivable state due to the engine stopping, and a cancellation processing unit that causes the diagnostic unit to stop performing abnormality diagnosis if the vehicle switches from a non-drivable state to a drivable state during the predetermined period.

Description

Technical Field

[0001] The present invention relates to a fuel pressure sensor diagnostic device.

Background Art

[0002] Regarding a fuel pressure sensor diagnostic device, for example, Patent Document 1 describes performing an abnormality diagnosis of a fuel pressure sensor provided in a fuel supply path of an engine during a soak period after the engine stops. The abnormality diagnosis is performed on the condition that the engine at the time of stop is sufficiently warmed up, and based on the correlation between the temperature and pressure of the fuel in the fuel supply path, it is confirmed that the detected value of the fuel pressure sensor after a predetermined time has elapsed since the engine stopped is about atmospheric pressure.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] For example, in a hybrid vehicle, if the vehicle travels only with the motor after the engine stops and before the abnormality diagnosis is executed, during the soak period after the travel, the abnormality diagnosis is performed while the execution conditions at the time of the previous engine stop remain satisfied. In this case, for example, the relationship between the fuel temperature and the fuel pressure in the fuel supply path may change according to the state of the vehicle during motor travel or during the soak period after travel. Therefore, the abnormality diagnosis is executed without the pressure of the fuel in the fuel supply path dropping to about atmospheric pressure, and as a result, there is a risk that an abnormality of the fuel pressure sensor is erroneously detected.

[0005] Therefore, the present invention has been made in view of the above problems, and an object thereof is to provide a fuel pressure sensor abnormality diagnostic device capable of suppressing erroneous detection of an abnormality of the fuel pressure sensor.

Means for Solving the Problems

[0006] The present invention relates to a fuel pressure sensor diagnostic device that, in response to the operation of a passenger, switches between a drivable state in which the vehicle can be driven by at least one of the engine and the motor, and a non-drivable state in which the vehicle cannot be driven, and performs an abnormality diagnosis of a fuel pressure sensor that detects the pressure of fuel in a fuel supply passage connected to the fuel injection device of the engine. The device includes: an estimation unit that estimates the temperature of the fuel in the fuel supply passage when the engine is stopped; a diagnostic unit that performs the abnormality diagnosis when the temperature is above a threshold, and a predetermined period has elapsed since the vehicle switched from the drivable state to the non-drivable state due to the engine being stopped; and a cancellation processing unit that causes the diagnostic unit to stop performing the abnormality diagnosis if the vehicle switches from the non-drivable state to the drivable state during the predetermined period.

[0007] In the fuel pressure sensor diagnostic device described above, the estimation unit estimates the temperature from parameters related to the engine's warm-up state, and the cancellation processing unit may change the parameters so that the temperature falls below the threshold when the vehicle switches from the non-running state to the drivable state during the predetermined period.

[0008] In the fuel pressure sensor diagnostic device described above, the parameters may include the cumulative value of the operating time and intake air volume from when the engine reaches a predetermined warm-up state until it is stopped. [Effects of the Invention]

[0009] According to the present invention, it is possible to suppress false detection of abnormalities in the fuel pressure sensor. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 is a diagram showing an example of a vehicle system. [Figure 2]Figure 2(a) shows an example of the time change in fuel temperature during a fuel pressure sensor abnormality diagnosis. Figure 2(b) shows an example of the time change in the detected value of the fuel pressure sensor during a fuel pressure sensor abnormality diagnosis. [Figure 3] Figure 3 is a diagram showing an example of an engine ECU (Electronic Control Unit). [Figure 4] Figure 4(a) is a time chart showing an example of the engine ECU's operation when an abnormality diagnosis is performed. Figure 4(b) is a time chart showing an example of the engine ECU's operation when the abnormality diagnosis is canceled. [Figure 5] Figure 5 is a flowchart showing an example of the process for diagnosing an anomaly in the fuel pressure sensor. [Figure 6] Figure 6 is a flowchart showing an example of the processing of warm-up determination parameters. [Modes for carrying out the invention]

[0011] (Outline configuration of the vehicle system) Figure 1 is a configuration diagram showing an example of a vehicle system S. The vehicle system S is mounted on a hybrid vehicle (hereinafter referred to as the vehicle) and includes an engine 4, a motor M, an engine ECU 1 that controls the engine 4, and a motor ECU 5 that controls the motor M. The engine 4 and motor M are the power sources for the vehicle, and the vehicle runs on the power of at least one of the engine 4 and motor M.

[0012] The engine 4 comprises a plurality of cylinders 40 arranged in series and in-cylinder injection valves 37. The in-cylinder injection valves 37 inject fuel into each cylinder 40. The in-cylinder injection valves 37 are electromagnetically driven on-off valves in which the amount of fuel injected is adjusted by energizing an electromagnetic coil for a predetermined energizing period to separate the valve body from the valve seat.

[0013] The engine 4 has an intake passage 41 having multiple intake ports 43 that communicate with each of the multiple cylinders 40, and an exhaust passage having multiple exhaust ports (not shown). In each of the cylinders 40, a piston (not shown) is housed to define a combustion chamber. The combustion chamber is opened and closed by intake valves and exhaust valves. The engine 4 is also equipped with spark plugs (not shown). The engine 4 also has a crankshaft 44 that is linked to the multiple pistons, and an intake camshaft 45 that drives the intake valves in conjunction with the crankshaft 44. A crank angle sensor 44a that detects the rotation angle of the crankshaft 44 and an air flow meter 42 that detects the amount of intake air (intake volume) introduced into the intake passage 41 are provided.

[0014] The vehicle system S also includes a fuel tank 21, a feed pump 22, a pressure regulator 23, a low-pressure fuel line 25, a high-pressure fuel pump 31, a high-pressure fuel line 35, a high-pressure delivery pipe 36, and a fuel pressure sensor 38. The fuel tank 21 stores gasoline, which is the fuel. The feed pump 22 pressurizes the fuel and discharges it into the low-pressure fuel line 25. The pressure regulator 23 adjusts the fuel discharged into the low-pressure fuel line 25 to a preset low-pressure supply pressure. The feed pump 22 is driven and controlled by the engine ECU 1.

[0015] The high-pressure fuel pump 31 includes, for example, a pump housing 31h, a plunger 31p that is slidable within the pump housing 31h, and a pressurized chamber 31a defined between the pump housing 31h and the plunger 31p. The volume of the pressurized chamber 31a changes according to the displacement of the plunger 31p. With the solenoid valve 32 open, pressurized fuel from the feed pump 22 is introduced into the pressurized chamber 31a via the low-pressure fuel piping 25. The fuel in the pressurized chamber 31a is pressurized to a high pressure by the plunger 31p and discharged into the high-pressure fuel piping 35.

[0016] The intake camshaft 45 of the engine 4 is equipped with a pump cam 49 that drives the plunger 31p. The high-pressure fuel pump 31 has a follower lifter 31f that is lifted and lowered by the pump cam 49, and a pump spring 31g that biases the follower lifter 31f toward the pump cam 49. The plunger 31p is linked to the follower lifter 31f and moves up and down together with the follower lifter 31f.

[0017] An electromagnetic valve 32 is provided at the fuel inlet of the pressurizing chamber 31a of the high-pressure fuel pump 31. The electromagnetic valve 32 has a valve body 32v, a coil 32c that drives the valve body 32v, and a spring 32k that constantly biases the valve body 32v in the open direction. The energization of the coil 32c is controlled by the engine ECU 1. When the coil 32c is energized, the valve body 32v blocks the low-pressure fuel pipe 25 and the pressurizing chamber 31a against the biasing force of the spring 32k. When the coil 32c is de-energized, the valve body 32v remains open due to the biasing force of the spring 32k.

[0018] A check valve 34 with a spring is provided in the high-pressure fuel pipe 35 between the high-pressure fuel pump 31 and the in-cylinder injection valve 37. The check valve 34 opens when the fuel pressure in the high-pressure fuel pump 31 becomes higher than the fuel pressure in the high-pressure fuel pipe 35 by a predetermined amount.

[0019] During the intake stroke of the high-pressure fuel pump 31, the electromagnetic valve 32 opens and the plunger 31p descends, filling the pressurizing chamber 31a with fuel from the low-pressure fuel pipe 25 of the low-pressure fuel pipe 25. During the pressurizing stroke, the electromagnetic valve 32 closes and as the plunger 31p rises, the volume of the pressurizing chamber 31a decreases and the fuel in the pressurizing chamber 31a is pressurized. During the discharge stroke, the check valve 34 opens when the force due to the fuel pressure in the pressurizing chamber 31a becomes greater than the biasing force of the spring of the check valve 34, and the pressurized fuel is supplied to the high-pressure fuel pipe 35 and the high-pressure delivery pipe 36. As described above, the up and down movement of the plunger 31p is realized by the rotation of the pump cam 49, and since the pump cam 49 is linked to the crankshaft 44 via the intake camshaft 45, the high-pressure fuel pump 31 is driven in linkage with the crankshaft 44.

[0020] In the high-pressure delivery pipe 36, high-pressure fuel pressurized by the high-pressure fuel pump 31 is accumulated via the high-pressure fuel pipe 35. The high-pressure delivery pipe 36 is connected to the in-cylinder injection valve 37. The high-pressure fuel pipe 35 and the high-pressure delivery pipe 36 supply high-pressure fuel from the high-pressure fuel pump 31 to the in-cylinder injection valve 37. The high-pressure delivery pipe 36 is an example of a fuel supply passage, and the in-cylinder injection valve 37 is an example of a fuel injection device.

[0021] The in-cylinder injection valve 37 directly injects high-pressure fuel into each interior of the cylinders 40 from within the high-pressure delivery pipe 36 in a predetermined order. The fuel pressure sensor 38 detects the fuel pressure within the high-pressure delivery pipe 36 and outputs the detected value to the engine ECU 1.

[0022] Further, the engine 4 is provided with a temperature sensor 53. The temperature sensor 53 detects the water temperature of the cooling water of the engine 4 and outputs the detected value to the engine ECU 1.

[0023] The vehicle is provided with an accelerator operation amount sensor 51 and an ignition switch 52. The accelerator operation amount sensor 51 detects the accelerator operation amount by the driver. The ignition switch 52 switches between on and off of the ignition according to the operation from the driver. The accelerator operation amount sensor 51 and the ignition switch 52 are electrically connected to the engine ECU 1 and the motor ECU 5. Here, the driver is an example of an occupant.

[0024] When the ignition switch 52 is turned from off to on, the engine ECU 1 and the motor ECU 5 are activated to set the engine and the motor M in a startable state respectively. Thereby, the vehicle switches from the Ready-off state to the Ready-on state. On the other hand, when the ignition switch 52 is turned from on to off, the vehicle switches from the Ready-on state to the Ready-off state. Here, the Ready-on state is an example of a drivable state in which driving by at least one of the engine 4 and the motor M is possible, and the Ready-off state is an example of a non-drivable state in which driving is impossible.

[0025] Furthermore, the engine ECU 1 controls the output torque of the engine 4 based on the detection value of the accelerator pedal operation sensor 51. The motor ECU 5 controls the output torque of the motor M based on the detection value of the accelerator pedal operation sensor 51.

[0026] The engine ECU 1 is electrically connected to the fuel pressure sensor 38. During the soak period after the engine 4 is stopped, if a predetermined time has elapsed since the engine 4 stopped and predetermined execution conditions are met, the engine ECU 1 performs a diagnosis of abnormality in the fuel pressure sensor 38. The engine ECU 1 is an example of a fuel pressure sensor diagnostic device.

[0027] (Fuel pressure sensor malfunction diagnosis) Figure 2(a) shows an example of the time change in fuel temperature (fuel temperature) when an abnormality diagnosis of the fuel pressure sensor 38 is performed. Figure 2(b) shows an example of the time change in the detected value (fuel pressure) of the fuel pressure sensor 38 when an abnormality diagnosis of the fuel pressure sensor 38 is performed. During the soak period after the end of the period of driving by the engine 4, the fuel pressure decreases along with the decrease in fuel temperature in the high-pressure delivery pipe 36. The abnormality diagnosis of the fuel pressure sensor 38 is performed under the condition that the engine 4 is sufficiently warmed up when stopped, and based on the correlation between fuel temperature and fuel pressure in the high-pressure delivery pipe 36, it is confirmed that the detected value of the fuel pressure sensor is at approximately atmospheric pressure when a predetermined period has elapsed since the engine 4 stopped and the fuel temperature has dropped to approximately ambient temperature.

[0028] The engine ECU 1 diagnoses the fuel pressure sensor 38 as being in a normal state if the detected value of the fuel pressure sensor 38 at a predetermined period of time (time Tdet) after the vehicle has stopped from the Ready On state to the Ready Off state (time Toff) due to the stopping of the engine 4 is within a predetermined normal range including atmospheric pressure (see symbol P1), and diagnoses the fuel pressure sensor 38 as being in an abnormal state if the detected value falls within an abnormal range larger than the normal range (see symbol P2). The predetermined period mentioned above is the time required for the detected value of the fuel pressure sensor 38 to drop to near atmospheric pressure after the engine 4 has stopped, assuming the fuel pressure sensor 38 is functioning normally.

[0029] If, after engine 4 has stopped, the vehicle changes from Ready Off to Ready On and runs on motor M alone before the abnormality diagnosis is performed, then during the soak period after the run, if the execution conditions for the previous engine 4 stop remain met, the abnormality diagnosis will be performed. In this case, the relationship between fuel temperature and fuel pressure in the high-pressure delivery pipe 36 may change depending on the state of the vehicle, for example, during the run on motor M or during the soak period after the run. For example, if the fuel pressure in the high-pressure delivery pipe 36 falls below the fuel pressure on the upstream side of the check valve 34 (high-pressure fuel pump 31 side), fuel will flow from the check valve 34 into the high-pressure delivery pipe 36, so even if the fuel temperature has dropped to around ambient temperature, the fuel pressure will be higher than atmospheric pressure. In such a case, the abnormality diagnosis may incorrectly detect an abnormality in the fuel pressure sensor 38.

[0030] In response to this, the engine ECU 1 stops the abnormality diagnosis if the vehicle switches from the Ready Off state to the Ready On state during the predetermined period mentioned above. This suppresses false detection of abnormalities in the fuel pressure sensor 38. Details are described below.

[0031] (Engine ECU function) Figure 3 is a configuration diagram showing an example of an engine ECU 1. The engine ECU 1 includes a microcontroller 1a and a soak timer 1b.

[0032] The soak timer 1b measures the time elapsed since the ignition switch 52 was turned off. In other words, the soak timer 1b measures the elapsed time during the soak period when the engine 4 or motor M is stopped. When the elapsed time reaches the predetermined time, the soak timer 1b activates the microcontroller 1a to diagnose an abnormality in the fuel pressure sensor 38.

[0033] The microcontroller 1a is an example of a computer. The microcontroller 1a has a CPU (Central Processing Unit) 10, ROM (Read Only Memory) 11, RAM (Random Access Memory) 12, non-volatile memory 13 such as SRAM (Static RAM), and a communication interface (INF) 14. The CPU 10 is electrically connected to the ROM 11, RAM 12, non-volatile memory 13, and INF 14 via a bus 19 so that they can input and output signals to and from each other. The microcontroller 1a is powered off and stops operating when the vehicle changes from the Ready On state to the Ready Off state, but is powered on and starts up when it receives a start signal from the soak timer 1b or when the vehicle changes from the Ready Off state to the Ready On state.

[0034] ROM11 stores the program that drives the CPU10. RAM12 functions as the working memory for the CPU10. INF14 is, for example, a communication circuit that handles communication between the CPU10 and, for example, the fuel pressure sensor 38, accelerator pedal operation sensor 51, temperature sensor 53, crank angle sensor 44a, and air flow meter 42.

[0035] When the CPU 10 reads a program from the ROM 11, it functions as an operation control unit 100, an engine control unit 101, an estimation unit 102, a parameter processing unit 103, and a diagnostic unit 104. The non-volatile memory 13 stores warm-up determination parameters 130, which are used to determine the success or failure of the execution conditions for abnormal diagnosis of the fuel pressure sensor 38. The warm-up determination parameters are an example of parameters related to the warm-up state of the engine 4.

[0036] The motion control unit 100 controls the overall operation of the microcontroller 1a. The motion control unit 100 instructs the engine control unit 101, estimation unit 102, parameter processing unit 103, and diagnostic unit 104 to perform actions according to a programmed sequence.

[0037] The engine control unit 101 determines the output torque of the engine 4 according to the value detected by the accelerator pedal operation sensor 51. The engine control unit 101 controls the engine 4 based on the values ​​detected by the crank angle sensor 44a, the air flow meter 42, and the fuel pressure sensor 38, as well as the output torque. At this time, the engine control unit 101 controls the feed pump 22 and the high-pressure fuel pump 31 so that the fuel pressure follows the target value according to the value detected by the fuel pressure sensor 38.

[0038] The estimation unit 102 estimates the fuel temperature in the high-pressure delivery pipe 36 when the engine 4 is stopped from the warm-up determination parameter 130. The warm-up determination parameter 130 includes, for example, the cumulative value of the operating time and intake volume from when the engine 4 reaches a predetermined warm-up state until it stops. At this time, the estimation unit 102 calculates the fuel temperature using a predetermined calculation formula based on the correlation between the cumulative values ​​of operating time and intake volume and the fuel temperature. The calculation formula is appropriately determined from prior simulation results and experimental results. For example, the estimation unit 102 may use the sum of the values ​​obtained by multiplying the cumulative values ​​of operating time and intake volume by a predetermined gain as the fuel temperature. In this way, the estimation unit 102 estimates the fuel temperature using the cumulative values ​​of operating time and intake volume, so it can obtain the fuel temperature without using a sensor that detects the fuel temperature. However, the estimation unit 102 may also estimate the fuel temperature using a sensor that detects the fuel temperature.

[0039] The parameter processing unit 103 performs processing related to the warm-up determination parameter 130. The parameter processing unit 103 measures the operating time from when the engine 4 reaches a predetermined warm-up state (for example, when the coolant temperature is 75°C or higher) until it stops, and calculates the cumulative value of the intake air volume during that period. At this time, the parameter processing unit 103 obtains the coolant temperature from, for example, the temperature sensor 53. When the engine 4 stops, the parameter processing unit 103 stores the cumulative value of the operating time and intake air volume as the warm-up determination parameter 130 in the non-volatile memory 13.

[0040] If the fuel temperature estimated by the estimation unit 102 is above a threshold, the diagnostic unit 104 performs an abnormality diagnosis of the fuel pressure sensor 38 when a predetermined period has elapsed since the vehicle switched from the Ready On state to the Ready Off state due to the engine 4 stopping. At this time, the soak timer 1b measures the elapsed time since the vehicle switched from the Ready On state to the Ready Off state, as described above. The diagnostic unit 104 performs an abnormality diagnosis when the elapsed time measured by the soak timer 1b reaches a predetermined period.

[0041] As described above, the diagnostic unit 104 determines whether the detected value of the fuel pressure sensor 38 is within the normal range, including atmospheric pressure. If the detected value is within the normal range, the diagnostic unit 104 determines that the fuel pressure sensor 38 is in a normal state, and if the detected value is outside the normal range (within the abnormal range), it determines that the fuel pressure sensor 38 is in an abnormal state.

[0042] Furthermore, the diagnostic unit 104 uses the condition that the fuel temperature estimated by the estimation unit 102 is above a threshold as the condition for performing abnormality diagnosis of the fuel pressure sensor 38. Thus, the condition for execution is that the engine 4 is sufficiently warmed up when stopped.

[0043] The parameter processing unit 103 instructs the diagnostic unit 104 to stop performing abnormality diagnosis if the vehicle switches from the Ready Off state to the Ready On state during the predetermined period described above. As a result, even if the vehicle is driven using only the motor M before the predetermined period has elapsed, abnormality diagnosis will not be performed, thus suppressing false detection of abnormalities in the fuel pressure sensor 38. Note that the parameter processing unit 103 is an example of a stop-processing unit.

[0044] The parameter processing unit 103 modifies the warm-up determination parameter 130 so that the temperature estimated by the estimation unit 102 falls below a threshold when the vehicle switches from the Ready Off state to the Ready On state during the predetermined period described above. For example, when the vehicle switches from the Ready Off state to the Ready On state, the parameter processing unit 103 resets the warm-up determination parameter 130 to zero. As a result, the warm-up determination parameter 130 stored when the engine 4 is stopped, i.e., the accumulated values ​​of the operating time and intake air volume, are reset to 0, so the temperature falls below the threshold.

[0045] (Example of engine ECU operation) Figure 4(a) is a time chart showing an example of the operation of the engine ECU1 when an abnormality diagnosis is performed. Figure 4(a) shows the time changes of the engine speed (rpm), Ready flag, parameter hold flag, and abnormality diagnosis execution flag of the engine 4. The Ready flag, parameter hold flag, and abnormality diagnosis execution flag are variables of the program executed by the microcontroller 1a.

[0046] The rotational speed is calculated, for example, from the value detected by the crank angle sensor 44a. The Ready flag, when set to "0", indicates the Ready off state, and when set to "1", indicates the Ready on state. The parameter retention flag, when set to "0", indicates that the warm-up determination parameter 130 is not held in the non-volatile memory 13, and when set to "1", indicates that the warm-up determination parameter 130 is held in the non-volatile memory 13. Therefore, the timing at which the parameter retention flag changes from "0" to "1" indicates the timing at which the process of storing the warm-up determination parameter 130 in the non-volatile memory 13 is executed, and the timing at which the parameter retention flag changes from "1" to "0" indicates the timing at which the process of clearing the warm-up determination parameter 130 stored in the non-volatile memory 13 to zero is executed. The abnormal diagnosis execution flag, when set to "0", indicates that the abnormal diagnosis of the fuel pressure sensor 38 is not being performed, and when set to "1", indicates that the abnormal diagnosis of the fuel pressure sensor 38 is being performed.

[0047] The driving period T1 is the period during which the vehicle is driven using engine 4. During the driving period T1, at time t1, the rotational speed decreases from N to 0 and engine 4 stops. At this time, the parameter processing unit 103 stores the cumulative value of the operating time and intake air volume from the time a predetermined warm-up state is reached until engine 4 stops during the driving period T1 as the warm-up determination parameter 130 in the non-volatile memory 13. At the following time t2, the driver turns off the ignition switch 52, and the vehicle changes from the Ready On state to the Ready Off state. As a result, the microcontroller 1a of the engine ECU 1 stops and the soak period T2 begins.

[0048] During the soak period T2, the soak timer 1b performs timing. The soak timer 1b starts the microcontroller 1a at time t3, after a predetermined period Ts has elapsed from time t2. At startup, the diagnostic unit 104 performs an abnormality diagnosis of the fuel pressure sensor 38. It is assumed that the warm-up determination parameter 130 satisfies the execution conditions. At the following time t4, the driver turns on the ignition switch 52, and the vehicle changes from the Ready Off state to the Ready On state. At this time, the parameter processing unit 103 resets the warm-up determination parameter 130 stored in the non-volatile memory 13 during the driving period T1 to zero. At the following time t5, the engine 4 starts and the rotational speed increases from 0.

[0049] Thus, when the warm-up determination parameter 130 satisfies the execution conditions, the diagnostic unit 104 performs an abnormality diagnosis of the fuel pressure sensor 38 after a predetermined period Ts has elapsed since the vehicle switched from the Ready On state to the Ready Off state due to the stopping of the engine 4.

[0050] Figure 4(b) is a time chart showing an example of the operation of the engine ECU1 when the abnormal diagnosis is canceled. In Figure 4(b), explanations of the symbols common to Figure 4(a) are omitted.

[0051] In this example, at time t30, after a period Tc shorter than the predetermined period Ts has elapsed since the start of the soak period T20 following the driving period T1 (time t2), the driver turns on the ignition switch 52, causing the vehicle to change from the Ready Off state to the Ready On state. At this time, the parameter processing unit 103 resets the warm-up determination parameter 130 stored in the non-volatile memory 13 during the driving period T1 to zero. As a result, the conditions for performing abnormal diagnosis of the fuel pressure sensor 38 are no longer met.

[0052] During the subsequent driving period T21, the vehicle runs using only the motor M with the engine 4 stopped. At the following time t32, the driver stops the motor M and turns off the ignition switch 52, causing the vehicle to change from the Ready On state to the Ready Off state. As a result, the microcontroller 1a of the engine ECU 1 stops, and a new soak period T22 begins.

[0053] The soak timer 1b continues to time even during the soak period T22. The soak timer 1b activates the microcontroller 1a at time t32, when a predetermined period Ts has elapsed from time t31, when the vehicle enters the Ready-Off state. However, the diagnostic unit 104 cancels the abnormality diagnosis of the fuel pressure sensor 38 because the warm-up judgment parameter 130 has been reset to zero and the execution conditions are not met. Therefore, even if the fuel pressure does not drop to approximately atmospheric pressure due to a change in the vehicle's state, the abnormality diagnosis is not performed, thus suppressing false detection of abnormalities in the fuel pressure sensor 38.

[0054] The symbols Fa for the parameter retention flag and Fb for the abnormal diagnosis execution flag indicate the respective flag values ​​in the comparative example. In the comparative example, it is assumed that the parameter processing unit 103 does not reset the warm-up determination parameter 130 to zero when the vehicle changes from the Ready Off state to the Ready On state (time t30). In this case, during the soak period T22 after the motor M driving period T21, the non-volatile memory 13 retains the warm-up determination parameter 130 stored at the end of the engine 4 driving period T1 (see symbol Fa). Therefore, after a predetermined period Ts has elapsed from the start of the soak period T22 (time t32), the diagnostic unit 104 performs an abnormal diagnosis of the fuel pressure sensor 38 (see symbol Fb). As a result, an abnormality in the fuel pressure sensor 38 is falsely detected as described above. In the comparative example, the warm-up determination parameter 130 in the non-volatile memory 13 is reset to zero at the next start of the engine 4 (time t4).

[0055] (Engine ECU processing) Figure 5 is a flowchart showing an example of the process for diagnosing an abnormality in the fuel pressure sensor 38. This process is performed periodically and repeatedly, for example, when the Ready off state is active. First, the soak timer 1b starts timing (St2) when the ignition switch (IG-SW) 52 switches from off to on (St1 Yes). If the ignition switch 52 remains off (St1 No), the process ends.

[0056] The soak timer 1b determines whether the time elapsed since the ignition switch 52 was turned off has reached a predetermined period Ts (St3). If the elapsed time is less than the predetermined period Ts (No in St3), the above determination is performed again (St3). If the elapsed time has reached the predetermined period Ts (Yes in St3), the microcontroller 1a is activated, and the estimation unit 102 estimates the fuel temperature of the engine 4 at the time of shutdown from the warm-up determination parameter 130 (St4).

[0057] Next, the diagnostic unit 104 compares the estimated fuel temperature with the threshold TH (St5). If fuel temperature ≤ TH is true (No in St5), the diagnostic unit 104 determines that the conditions for performing an abnormal diagnosis of the fuel pressure sensor 38 are not met and terminates the process without performing the abnormal diagnosis. If fuel temperature > TH is true (Yes in St5), the diagnostic unit 104 determines that the conditions for performing an abnormal diagnosis of the fuel pressure sensor 38 are met and performs the following abnormal diagnoses (St6~St9).

[0058] In the abnormality diagnosis, the diagnostic unit 104 first acquires the fuel pressure (detected value) from the fuel pressure sensor 38 (St6). Next, the diagnostic unit 104 determines whether the fuel pressure is within a predetermined normal range (Pa ≤ fuel pressure ≤ Pb) (St7). If the fuel pressure is within the normal range (Yes in St7), the diagnostic unit 104 determines that the fuel pressure sensor 38 is in a normal state (St8). If the fuel pressure is not within the normal range (it is in the abnormal range) (No in St7), the diagnostic unit 104 determines that the fuel pressure sensor 38 is in an abnormal state (St9). In this way, the abnormality diagnosis process for the fuel pressure sensor 38 is performed.

[0059] Figure 6 is a flowchart showing an example of the processing of the warm-up determination parameter 130. This process is executed repeatedly, for example, periodically. First, when the vehicle switches from the Ready Off state to the Ready On state (Yes in St21), that is, when the microcontroller 1a starts up, the parameter processing unit 103 resets the warm-up determination parameter 130 stored in the non-volatile memory 13 to zero (St22).

[0060] As a result, at times t4 and t30 in Figures 4(a) and 4(b), the parameter retention flag changes from "1" to "0". Since the warm-up judgment parameter 130 is cleared to zero, the conditions for performing the abnormal diagnosis of the fuel pressure sensor 38 are no longer met. Therefore, in the judgment process of St5 described above, fuel temperature > TH is not met, and the abnormal diagnosis is canceled. Also, if the vehicle is in the Ready-off state (No. of St21), this process terminates.

[0061] After the warm-up determination parameter 130 is reset to zero (St22), the parameter processing unit 103 determines whether or not the engine 4 has started (St23). At this time, the parameter processing unit 103 calculates the rotational speed of the engine 4 from the value detected by the crank angle sensor 44a. If the rotational speed increases from, for example, 0 rpm, it determines that the engine 4 has started. If the rotational speed remains at, for example, 0 rpm, it determines that the engine 4 is stopped.

[0062] If engine 4 is stopped (No in St23), this process ends. If engine 4 is started (Yes in St23), the parameter processing unit 103 compares the coolant temperature detected by the water temperature sensor with a predetermined value Tw (e.g., 75°C) (St24). If temperature > Tw is true (Yes in St24), the parameter processing unit 103 determines that engine 4 is in a predetermined warm-up state and calculates the cumulative values ​​of the engine 4's operating time and intake volume while it is maintained in the predetermined warm-up state (St25). If temperature ≤ Tw is true (No in St24), the parameter processing unit 103 determines that engine 4 is not in the predetermined warm-up state and resets the cumulative values ​​of the engine 4's operating time and intake volume to zero (St26).

[0063] The parameter processing unit 103 determines whether the engine 4 has stopped or not (St27). At this time, the parameter processing unit 103 determines whether the engine 4 has stopped based on the rotational speed calculated from the detected value of the crank angle sensor 44a, as described above. If the engine 4 has not stopped (No. of St27), the processes from St24 onwards are performed again.

[0064] Furthermore, if engine 4 stops (Yes in St27), the parameter processing unit 103 stores the accumulated values ​​of engine 4's operating time and intake air volume as the warm-up determination parameter 130 in the non-volatile memory 13 (St28). As a result, at time t1 in Figures 4(a) and 4(b), the parameter retention flag changes from "0" to "1".

[0065] In this manner, the parameter processing unit 103 instructs the diagnostic unit 104 to stop performing abnormality diagnosis of the fuel pressure sensor 38 if the vehicle switches from the Ready Off state to the Ready On state during a predetermined period. Therefore, after the vehicle has been driven using only the motor M, the abnormality diagnosis is not performed, and false detection of abnormalities in the fuel pressure sensor 38 is suppressed. In this example, the diagnostic unit 104 was instructed to stop the abnormality diagnosis by clearing the warm-up judgment parameter 130 to zero, but the means for stopping the abnormality diagnosis is not limited to this. For example, if the parameter processing unit 103 detects the start of a period of driving using only the motor M (T21 above) by communicating with the motor ECU 5, it may instruct the diagnostic unit 104 to stop the abnormality diagnosis in advance by setting a predetermined flag during the driving period.

[0066] The embodiments described above are preferred examples of the present invention. However, the invention is not limited thereto, and various modifications are possible without departing from the spirit of the invention. [Explanation of Symbols]

[0067] 1 Engine ECU (fuel pressure sensor diagnostic device), 4 Engine, 10 CPU, 36 High-pressure delivery pipe (fuel supply line), 37 In-cylinder injection valve, 38 Fuel pressure sensor, 52 Ignition switch, 101 Engine control unit, 102 Estimation unit, 103 Parameter processing unit (cancellation processing unit), 104 Diagnostic unit, 130 Warm-up judgment parameter (parameter), M Motor

Claims

1. In a vehicle that switches between a drivable state, in which the vehicle can be driven using at least one of the engine and motor, and a non-drivable state, in which the vehicle cannot be driven, in response to the operator's input, a fuel pressure sensor diagnostic device that performs abnormality diagnosis of a fuel pressure sensor that detects the fuel pressure in the fuel supply passage connected to the engine's fuel injection device, An estimation unit that estimates the temperature of the fuel in the fuel supply line when the engine is stopped, If the temperature is above a threshold, and a predetermined period has elapsed since the vehicle switched from the drivable state to the non-drivable state due to the engine stopping, the diagnostic unit performs the abnormality diagnosis. The system includes a cancellation processing unit that causes the diagnostic unit to stop performing the abnormality diagnosis if the vehicle switches from the inoperable state to the drivable state during the predetermined period. Fuel pressure sensor diagnostic device.

2. The estimation unit estimates the temperature from parameters related to the warm-up state of the engine, The termination processing unit modifies the parameters so that the temperature falls below the threshold when the vehicle switches from the non-operational state to the operable state during the predetermined period. The fuel pressure sensor diagnostic device according to claim 1.

3. The aforementioned parameters include the cumulative value of the operating time and intake volume from when the engine reaches a predetermined warm-up state until it is stopped. The fuel pressure sensor diagnostic device according to claim 2.

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