JP7600917B2 - Control device for internal combustion engine - Google Patents

Description

The present invention relates to a control device for an internal combustion engine.

The internal combustion engine described in Patent Document 1 is equipped with a fuel pressure sensor that detects the pressure of the fuel supplied to the fuel injection valve. The control device for this internal combustion engine is configured to add a warm-up parameter indicating the degree of warm-up state of the internal combustion engine while the internal combustion engine is operating. Meanwhile, the value of the warm-up parameter is maintained without being updated until a predetermined waiting time has elapsed since the operation of the internal combustion engine was stopped. Then, when the waiting time has elapsed, the warm-up parameter is subtracted.

Then, if an abnormality diagnosis condition is met, one of the conditions being that the warm-up parameter is equal to or greater than a predetermined value, after a predetermined time has elapsed since the internal combustion engine stopped operating, an abnormality diagnosis process is executed to diagnose whether or not an abnormality has occurred in the fuel pressure sensor.

JP 2018-96278 A

However, until a predetermined period of time has elapsed since the engine was stopped, the amount of heat received by the fuel due to radiant heat from the internal combustion engine, etc., may exceed the amount of heat released by the fuel, in which case the fuel temperature will rise. For this reason, if the value of the warm-up parameter is maintained without being updated from when the operation of the internal combustion engine is stopped until the above-mentioned waiting time has elapsed, such an increase in fuel temperature will not be appropriately reflected in the warm-up parameter. As a result, the frequency with which the above-mentioned abnormality diagnosis conditions are met while the engine is stopped decreases, which may result in the frequency with which the abnormality diagnosis process is executed less frequently.

The control device for an internal combustion engine that solves the above problem is applied to an internal combustion engine equipped with a fuel pressure sensor that detects the pressure of fuel supplied to a fuel injection valve. This control device executes a calculation process that calculates a warm-up parameter indicating the degree of warm-up state of the internal combustion engine, and an abnormality diagnosis process that diagnoses whether or not an abnormality has occurred in the fuel pressure sensor when an abnormality diagnosis condition including a condition that the warm-up parameter is equal to or greater than a predetermined judgment value after a predetermined time has elapsed since the operation of the internal combustion engine has stopped is established. The calculation process calculates the convergence temperature of the fuel while the engine is stopped based on the heat balance of the fuel when the operation of the internal combustion engine is stopped, and executes a process of adding the warm-up parameter when an addition condition during stop is established including a condition that the calculated convergence temperature is higher than the estimated temperature of the fuel calculated based on the operation time of the internal combustion engine.

According to this configuration, if the convergence temperature is higher than the estimated temperature and it is determined that the fuel temperature will rise while the engine is stopped, the warm-up parameter is added. Therefore, the frequency with which the abnormality diagnosis condition is satisfied while the engine is stopped increases, and the frequency with which the abnormality diagnosis process is executed can be increased.

1 is a diagram showing a configuration of an internal combustion engine and a control device according to an embodiment; 4 is a flowchart showing a procedure of a process executed by a control device according to the embodiment. 5 is a flowchart showing the procedure of a calculation process executed by the control device according to the embodiment. 1 is a timing chart showing the operation of the embodiment, in which (A) is a change in engine speed, (B) is a change in vehicle speed, (C) is a change in engine operating state, (D) is a change in fuel temperature, (E) is a time elapsed since the engine was stopped, and (F) is a change in warm-up parameters.

Hereinafter, an embodiment will be described with reference to the drawings.
<Configuration of Internal Combustion Engine and Control Device>
As shown in FIG. 1, an internal combustion engine 10 mounted on a vehicle 500 includes a plurality of cylinders #1 to #4.

A throttle valve 14 is provided in an intake passage 12 of the internal combustion engine 10 .
A branch pipe 12 a provided in a downstream portion of the intake passage 12 is provided with a port injection valve 16 that injects fuel into an intake port of the internal combustion engine 10 .

Air flowing through the intake passage 12 and fuel injected from the port injection valve 16 flow into the combustion chambers 20 of each of the cylinders #1 to #4 as the intake valves 18 open.
Each of cylinders #1 to #4 of the internal combustion engine 10 is provided with an in-cylinder injection valve 22 that directly injects fuel into the combustion chamber 20. The in-cylinder injection valves 22 are connected to a delivery pipe 23. A high-pressure pump 300 is connected to the delivery pipe 23, which pressurizes fuel from a fuel tank (not shown) and sends the high-pressure fuel to the delivery pipe 23. A fuel pressure sensor 89 is attached to the delivery pipe 23 to detect a fuel pressure PF, which is the pressure of the fuel supplied to the in-cylinder injection valve 22.

The mixture of air and fuel supplied to the combustion chamber 20 is burned by the spark discharge of the ignition plug 24. The combustion energy generated at that time is converted into the rotational energy of the output shaft 26.

The air-fuel mixture combusted in the combustion chamber 20 is discharged as exhaust gas into an exhaust passage 30 when an exhaust valve 28 opens.
The output shaft 26 is mechanically connected to a carrier C of a planetary gear mechanism 50 constituting a power split device. A rotating shaft 52a of a first motor generator (hereinafter referred to as first MG) 52 is mechanically connected to a sun gear S of the planetary gear mechanism 50. In addition, a rotating shaft 54a of a second motor generator (hereinafter referred to as second MG) 54 and drive wheels 60 are mechanically connected to a ring gear R of the planetary gear mechanism 50.

The first MG 52 and the second MG 54 exchange power with the battery 250 via the PCU (Power Control Unit) 200. The PCU 200 includes a converter that boosts and outputs the DC voltage input from the battery 250, and an inverter that converts the DC voltage boosted by the converter into an AC voltage and outputs it to each of the MGs 52 and 54.

The control device 70 controls the internal combustion engine 10, and operates each operating part of the internal combustion engine 10, such as the throttle valve 14, port injection valve 16, in-cylinder injection valve 22, spark plug 24, and high-pressure pump 300, to control the torque and exhaust component ratio as control quantities. Note that FIG. 1 shows the operating signals MS1 to MS4 of the throttle valve 14, port injection valve 16, in-cylinder injection valve 22, and spark plug 24, respectively.

Furthermore, the control device 70 controls the first MG 52 as a control object, and operates the inverter via the PCU 200 to control the rotation speed, which is a control variable thereof.
Furthermore, the control device 70 controls the second MG 54 and operates the inverter via the PCU 200 to control the torque, which is the control variable of the second MG 54.

In order to control the control amount of the internal combustion engine 10, the control device 70 refers to the intake air amount Ga detected by the air flow meter 80, the output signal Scr of the crank angle sensor 82, and the cooling water temperature THW detected by the water temperature sensor 86. The control device 70 also refers to the oil temperature THO, which is the temperature of the lubricating oil of the internal combustion engine 10 detected by the oil temperature sensor 87, the intake temperature THA detected by the intake temperature sensor 88, and the fuel pressure PF detected by the fuel pressure sensor 89. In order to control the control amount of the first MG 52 and the second MG 54, the control device 70 also refers to the output signal Sm1 of the first rotation angle sensor 90 that detects the rotation angle of the first MG 52, and the output signal Sm2 of the second rotation angle sensor 92 that detects the rotation angle of the second MG 54. In addition, the control device 70 refers to the accelerator operation amount ACCP, which is the amount of depression of the accelerator pedal detected by the accelerator sensor 94, and the vehicle speed SP of the vehicle 500 detected by the vehicle speed sensor 95, in order to control the control amounts of the internal combustion engine 10, the first MG 52, and the second MG 54.

Although not shown, the control device 70 is made up of a plurality of control units, such as a control unit for the internal combustion engine 10 and a control unit for the PCU 200 .
The control device 70 calculates the engine speed NE based on the output signal Scr of the crank angle sensor 82. The control device 70 also calculates the engine load factor KL based on the engine speed NE and the intake air amount Ga. Here, the engine load factor KL represents the ratio of the current cylinder inflow air amount to the cylinder inflow air amount when the internal combustion engine 10 is steadily operated with the throttle valve 14 fully open at the current engine speed NE. The cylinder inflow air amount is the amount of intake air flowing into each cylinder during the intake stroke.

The control device 70 includes a CPU 72, a ROM 74, and peripheral circuits 76, which are capable of communicating with each other via a communication line 78. Here, the peripheral circuits 76 include a circuit that generates a clock signal that regulates internal operations, a power supply circuit, a reset circuit, etc. The control device 70 controls various control quantities by the CPU 72 executing a program stored in the ROM 74.

For example, the control device 70 calculates the required torque of the vehicle 500 based on the accelerator operation amount ACCP and the vehicle speed SP. The control device 70 also controls the required output PE of the internal combustion engine 10 and the output torque of the first MG 52 and the second MG 54 so as to satisfy the required torque of the vehicle 500.

The control device 70 also performs intermittent operation to automatically stop the operation of the internal combustion engine 10 when a predetermined stop condition is met, and automatically start the internal combustion engine 10 when a predetermined start condition is met.

<Processing Executed by the Control Device 70>
The control device 70 executes an abnormality diagnosis process to diagnose whether or not an abnormality has occurred in the fuel pressure sensor 89. Note that the abnormality referred to here means that the output value of the fuel pressure sensor 89 is not output correctly.

Figure 2 shows the procedure for the abnormality diagnosis process executed by the control device 70. The process shown in Figure 2 is realized by the CPU 72 executing a program stored in the ROM 74. The process shown in Figure 2 is repeatedly executed at a predetermined interval when the engine is stopped by the intermittent operation described above or when the engine is stopped by the vehicle driver. In the following, the step number of each process is represented by a number preceded by "S".

In the series of processes shown in FIG. 2, the CPU 72 determines whether the elapsed time Ts after the engine is stopped is equal to or greater than the third reference value Tsref3 (S100). The elapsed time Ts is a value that the control device 70 starts measuring when the engine is stopped, and is reset to "0" when the engine start is started. The third reference value Tsref3 is a preset value, and is set to, for example, a time of about several hours.

When it is determined that the elapsed time Ts is equal to or greater than the third reference value Tsref3 (S100: YES), the CPU 72 acquires a warm-up parameter Ph (S110). The warm-up parameter Ph is a value that indicates the degree of warm-up of the internal combustion engine 10, and is a value that correlates with the fuel temperature in the delivery pipe 23 to which the fuel pressure sensor 89 is attached. The calculation of this warm-up parameter Ph will be described later.

Next, the CPU 72 determines whether the acquired warm-up parameter Ph is equal to or greater than the reference value Phref (S120). The reference value Phref is a value for determining whether the temperature of the fuel in the delivery pipe 23 when the engine is stopped is high enough to properly diagnose an abnormality in the fuel pressure sensor 89. More specifically, the reference value Phref is a value for determining whether the fuel temperature has been raised to a level at which the pressure in the delivery pipe 23 can be reduced to atmospheric pressure due to a reduction in the volume of the fuel accompanying a drop in the temperature of the fuel in the delivery pipe 23 during the period until the elapsed time Ts reaches the third reference value Tsref3. The reference value Phref is set to an appropriate value determined in advance by experiments or the like.

If it is determined that the warm-up parameter Ph is equal to or greater than the reference value Phref (S120: YES), the CPU 72 executes an abnormality diagnosis process for the fuel pressure sensor 89 (S130). In this abnormality diagnosis process, the CPU 72 acquires the fuel pressure PF, which is the output value of the fuel pressure sensor 89. It then determines whether the acquired fuel pressure PF is within a predetermined pressure range (e.g., a pressure range equivalent to atmospheric pressure). If the fuel pressure PF is within the predetermined pressure range, it is determined that no abnormality has occurred in the fuel pressure sensor 89. On the other hand, if the fuel pressure PF is outside the predetermined pressure range, it is determined that an abnormality has occurred in the fuel pressure sensor 89.

When the CPU 72 has finished the process of S130 or when a negative determination is made in the process of S100 or S120, the CPU 72 temporarily ends the series of processes shown in FIG.
3 shows a procedure for calculating the warm-up parameter Ph, which is executed by the control device 70. The process shown in FIG. 3 is realized by the CPU 72 executing a program stored in the ROM 74 at every predetermined execution period ΔT.

In the series of processes shown in FIG. 3, the CPU 72 determines whether the engine is stopped (S200). Then, if it is determined that the engine is not stopped, that is, the engine is operating (S200: NO), the CPU 72 updates the warm-up parameter Ph by adding the execution period ΔT to the current warm-up parameter Ph (S230). Then, this process is temporarily terminated. In this way, the process of S230 is repeatedly executed while the engine is operating. Therefore, the increase in the warm-up parameter Ph while the engine is operating becomes a value that indicates the operating time of the internal combustion engine 10.

On the other hand, when it is determined in the process of S200 that the engine is stopped (S200: YES), the CPU 72 determines whether the elapsed time Ts is equal to or less than a first determination value Tsref1 (S210). The first determination value Tsref1 is the time during which the fuel temperature in the delivery pipe 23 may increase after the engine is stopped. This first determination value Tsref1 is a time shorter than the third determination value Tsref3 (e.g., about several tens of seconds), and is set to an appropriate value determined in advance by experiments, etc.

When it is determined that the elapsed time Ts is equal to or less than the first reference value Tsref1 (S210: YES), the CPU 72 determines whether or not a stop-time addition condition is satisfied (S220). This stop-time addition condition is a condition for determining whether or not to perform an addition process of the warm-up parameter Ph while the engine is stopped. When the stop-time addition condition is satisfied, the process of S230 is executed, thereby executing the addition process of the warm-up parameter Ph.

For example, when all of the following conditions A to E are satisfied, it is determined that the stop-time addition condition is met.
Condition A: The fuel injection stop time is equal to or shorter than a predetermined time. This condition (A) is determined to be satisfied when an affirmative determination is made in S210.

Condition B: The inequality "converged fuel temperature THFc>estimated fuel temperature THFe+predetermined value α" is satisfied.
The convergence fuel temperature THFc is calculated based on the heat balance of the fuel in the delivery pipe 23 when the internal combustion engine 10 is stopped, and is the convergence temperature of the fuel when the engine is stopped. More specifically, the CPU 72 acquires the oil temperature THO, the vehicle speed SP, and the intake air temperature THA when the engine is stopped. The oil temperature THO is a value related to the amount of heat received by the fuel, and the vehicle speed SP and the intake air temperature THA are values related to the amount of heat released by the fuel. The CPU 72 calculates the convergence fuel temperature THFc based on the oil temperature THO, the vehicle speed SP, and the intake air temperature THA. In this embodiment, the convergence fuel temperature THFc is calculated so that the higher the oil temperature THO, the higher the convergence fuel temperature THFc. In addition, the higher the vehicle speed SP, the greater the amount of heat released by the fuel due to the running wind. Therefore, the convergence fuel temperature THFc is calculated so that the higher the vehicle speed SP, the lower the convergence fuel temperature THFc. The lower the intake air temperature THA, the greater the amount of heat radiation from the fuel due to the ambient temperature of the delivery pipe 23. Therefore, the convergence fuel temperature THFc is calculated so that the lower the intake air temperature THA, the lower the convergence fuel temperature THFc becomes.

The estimated fuel temperature THFe is an estimated value of the fuel temperature in the delivery pipe 23 calculated based on the operating time of the internal combustion engine 10. More specifically, the CPU 72 measures the operating time Td of the internal combustion engine 10 while the engine is operating. The CPU 72 then calculates the estimated fuel temperature THFe so that the estimated fuel temperature THFe becomes higher as the operating time Td becomes longer. An upper limit is set for the estimated fuel temperature THFe. When the engine operation is stopped, the estimated fuel temperature THFe calculated at that time is maintained. In this embodiment, the lowest value within the expected range of the fuel temperature in the delivery pipe 23 while the engine is operating is calculated as the estimated fuel temperature THFe.

The above condition B is a condition for determining that the convergence fuel temperature THFc is higher than the estimated fuel temperature THFe. If condition B is satisfied, it is determined that there is a possibility that the fuel temperature in the delivery pipe 23 will rise for a predetermined period of time after the engine is stopped (for example, the period until at least the first determination value Tsref1 has elapsed).

Condition C: The drop in oil temperature THO while the engine is stopped is equal to or lower than a preset value. If the drop in oil temperature becomes greater, the amount of heat received by the fuel decreases, making it difficult for the fuel temperature in the delivery pipe 23 to increase. In this case, it is not a suitable state for performing the addition process of the warm-up parameter Ph. Therefore, condition C is set to avoid performing the addition process in such an unsuitable state.

Condition D: The execution time Tz of the addition process while the engine is stopped is equal to or less than the default value Tzref. The execution time of the addition process is the total time during which the addition process of the warm-up parameter Ph is performed while the engine is stopped, and is measured by the control device 70. This condition D is set to prevent the warm-up parameter Ph from becoming excessively large due to the execution of the addition process while the engine is stopped. The default value Tzref is set to a time shorter than the first judgment value Tsref1. Note that the execution time Tz is reset at the latest by the time the next engine stop is started.

Condition E: The vehicle speed SP while the engine is stopped is equal to or lower than the threshold value SPref. If the vehicle speed is high, the amount of heat dissipated from the fuel increases, making it difficult for the fuel temperature in the delivery pipe 23 to rise. In this case, the state is not suitable for performing the addition process of the warm-up parameter Ph. Therefore, condition E is set to avoid performing the addition process in such an unsuitable state. In this embodiment, the threshold value SPref is set to a value close to "0", but this value can be changed as appropriate.

If it is determined in S220 that the stop-time addition condition is satisfied (S220: YES), the CPU 72 executes the process of S230 described above to perform the addition process of the warm-up parameter Ph. Then, this process is temporarily terminated.

When it is determined in S210 that the elapsed time Ts exceeds the first determination value Tsref1 (S210: NO), the CPU 72 determines whether the elapsed time Ts is equal to or greater than the second determination value Tsref2 (S240). The second determination value Tsref2 is the elapsed time at which the fuel temperature in the delivery pipe 23 may begin to decrease after the engine is stopped. This second determination value Tsref2 is shorter than the third determination value Tsref3 and longer than the first determination value Tsref1, and is set to an appropriate value determined in advance by experiments, etc.

When it is determined that the elapsed time Ts is equal to or greater than the second reference value Tsref2 (S240: YES), the CPU 72 calculates a subtraction value Phd for decreasing the warm-up parameter Ph (S250). In S250, the CPU 72 acquires the current vehicle speed SP and intake air temperature THA. The CPU 72 then calculates the subtraction value Phd based on the vehicle speed SP and intake air temperature THA. In this embodiment, the higher the vehicle speed SP, the greater the amount of heat released from the fuel due to the running wind. Therefore, the subtraction value Phd is calculated so that the higher the vehicle speed SP, the greater the value of the subtraction value Phd. In addition, the lower the intake air temperature THA, the greater the amount of heat released from the fuel due to the ambient temperature of the delivery pipe 23. Therefore, the lower the intake air temperature THA, the greater the value of the subtraction value Phd.

After calculating the subtraction value Phd in this manner, the CPU 72 then updates the warm-up parameter Ph by subtracting the subtraction value Phd from the current warm-up parameter Ph (S260). Then, this process is temporarily terminated.

If the CPU 72 judges negative in the process of S200 or S240, it temporarily ends the series of processes shown in FIG. 3. Therefore, if the CPU 72 judges negative in the process of S200 or S240, the warm-up parameter Ph is not updated and is maintained at the current value.

<Action>
The operation of this embodiment will now be described.
Figure 4 shows the changes in various values while the engine is operating and while the engine is stopped. Figure 4(A) shows the changes in engine rotation speed. Figure 4(B) shows the changes in vehicle speed. Figure 4(C) shows the changes in engine operating conditions. Figure 4(D) shows the changes in fuel temperature THF in the delivery pipe 23. Figure 4(E) shows the elapsed time Ts after the engine is stopped. Figure 4(F) shows the changes in warm-up parameters.

Before time t1, the vehicle 500 is in a running state, but the operation of the internal combustion engine 10 is stopped.
When the engine operation starts at time t1 and the engine operation state becomes the operating state, the elapsed time Ts is reset. In addition, the temperature of the delivery pipe 23 increases due to heat generated by the internal combustion engine 10, so the fuel temperature THF increases. In addition, the value of the warm-up parameter Ph increases.

When the engine operation is stopped at time t2, measurement of the elapsed time Ts starts, and the elapsed time Ts increases. Also, even if the engine operation is stopped, if the amount of heat received is greater than the amount of heat released in the heat balance of the fuel in the delivery pipe 23, the fuel temperature THF increases.

Here, even if the engine operation is stopped at time t2, the vehicle speed SP exceeds the threshold value SPref, so the above condition E is not satisfied. Therefore, the above-mentioned stop-while-stop addition condition is not satisfied, and the value of the warm-up parameter Ph is maintained at the value at time t2.

After that, at time t3, the vehicle speed SP becomes equal to or lower than the threshold value SPref, and if all of the above conditions A to E are met at this time, the stop-while-stopped addition condition is met. Therefore, from time t3 onwards, the value of the warm-up parameter Ph increases.

Then, at time t4, when the elapsed time Ts exceeds the first judgment value Tsref1, the above condition A is no longer satisfied, and the stop-time addition condition is no longer satisfied. Therefore, the addition process of the warm-up parameter Ph while the engine is stopped ends at time t4. Therefore, after time t4, the value of the warm-up parameter Ph at time t4 is maintained until the elapsed time Ts becomes equal to or greater than the second judgment value Tsref2.

Although not shown, when the elapsed time Ts becomes equal to or greater than the second reference value Tsref2, the above-mentioned processes of S250 and S260 are executed, and the warm-up parameter Ph is subtracted. Then, when the elapsed time Ts becomes equal to or greater than the third reference value Tsref3, the warm-up parameter Ph is compared with the reference value Phref. Then, if the warm-up parameter Ph is equal to or greater than the reference value Phref, the process of S130 shown in FIG. 2 is executed, that is, the abnormality diagnosis process for the fuel pressure sensor 89 is executed.

＜Effects＞
The effects of this embodiment will be described.
(1) When the above-mentioned addition condition during stop is satisfied, including the convergence fuel temperature THFc being higher than the estimated fuel temperature THFe (the above-mentioned condition B), the addition process of the warm-up parameter Ph is executed even while the engine is stopped.

Therefore, when the convergence fuel temperature THFc is higher than the estimated fuel temperature THFe and it is determined that the fuel temperature THF will rise while the engine is stopped, the warm-up parameter Ph is added and becomes larger. As a result, the frequency of the abnormality diagnosis condition being met, including the warm-up parameter Ph being equal to or greater than the reference value Phref while the engine is stopped, increases. And, by increasing the frequency of the abnormality diagnosis condition being met in this way, the frequency of the execution of the abnormality diagnosis process described above increases.

<Example of change>
The above embodiment can be modified as follows: The above embodiment and the following modifications can be combined with each other to the extent that no technical contradiction occurs.

The above stop-time addition conditions may include at least condition B. For example, any of the conditions other than condition B may be omitted, or the conditions other than condition B may be changed to another condition.

In the process of S230, the value added to the warm-up parameter Ph may be changed as appropriate.
In the process of S260, the value to be subtracted from the warm-up parameter Ph may be changed as appropriate.

Instead of the intake air temperature THA, the outside air temperature may be acquired.
Instead of the oil temperature THO, the cooling water temperature THW may be acquired.
The internal combustion engine 10 may not be equipped with the port injection valve 16 .

- In the above embodiment, the configuration of the vehicle 500 is not limited to the example of the above embodiment. For example, the vehicle may not be equipped with the first MG 52 or the second MG 54, and may be equipped with only the internal combustion engine 10 as a prime mover.

The control device 70 is not limited to a device equipped with a CPU 72 and a ROM 74 and executing software processing. For example, it may be equipped with a dedicated hardware circuit, such as an ASIC, that performs hardware processing of at least a portion of what was processed by software in the above embodiment. That is, the control device may have any of the following configurations (a) to (c). (a) It comprises a processing device that executes all of the above processing according to a program, and a program storage device, such as a ROM, that stores the program. (b) It comprises a processing device and program storage device that executes a portion of the above processing according to a program, and a dedicated hardware circuit that executes the remaining processing. (c) It comprises a dedicated hardware circuit that executes all of the above processing. Here, there may be multiple software execution devices equipped with a processing device and program storage device, and multiple dedicated hardware circuits.

Reference Signs List 10 internal combustion engine 12 intake passage 16 port injection valve 20 combustion chamber 22 in-cylinder injection valve 23 delivery pipe 26 output shaft 30 exhaust passage 50 planetary gear mechanism 52 first motor generator 54 second motor generator 60 drive wheel 70 control device 72 CPU
74...ROM
86... water temperature sensor 87... oil temperature sensor 88... intake air temperature sensor 89... fuel pressure sensor 94... accelerator sensor 95... vehicle speed sensor 200... PCU
250... battery 300... high pressure pump 500... vehicle

Claims (1)

A control device applied to an internal combustion engine having a fuel pressure sensor that detects the pressure of fuel supplied to a fuel injection valve,
A calculation process for calculating a warm-up parameter indicating a degree of a warm-up state of the internal combustion engine;
and when an abnormality diagnosis condition is satisfied, the abnormality diagnosis process diagnoses whether or not an abnormality has occurred in the fuel pressure sensor, the abnormality diagnosis process including a condition that the warm-up parameter is equal to or greater than a predetermined determination value after a predetermined time has elapsed since the operation of the internal combustion engine has stopped.
The calculation process calculates a convergence temperature of the fuel while the internal combustion engine is stopped based on a heat balance of the fuel when the operation of the internal combustion engine is stopped, and executes a process of adding the warm-up parameter when a stoppage addition condition is satisfied, the condition including a condition that the calculated convergence temperature is higher than an estimated temperature of the fuel calculated based on an operation time of the internal combustion engine.

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