Internal combustion engine control device and control method

Abstract

The present application provides an internal combustion engine control device and control method. The control device is applied to an internal combustion engine provided with a cylinder and an in-cylinder injection valve that injects gaseous fuel into the cylinder. A CPU of the control device performs the following steps: acquires a pressure in the cylinder, i.e., in-cylinder pressure, and a pressure of the gaseous fuel supplied to the in-cylinder injection valve, i.e., supply fuel pressure, in one combustion cycle; calculates an amount of combustion gas flowing from the cylinder into the in-cylinder injection valve, i.e., reverse flow, in one combustion cycle of the cylinder. The CPU calculates the reverse flow in a manner that the higher the in-cylinder pressure, the more the reverse flow, and the lower the supply fuel pressure, the more the reverse flow.

Description

Technical Field

[0001] This disclosure relates to an internal combustion engine control device and control method applicable to an internal combustion engine, the internal combustion engine having an in-cylinder injection valve for injecting gaseous fuel into a cylinder. Background Technology

[0002] Japanese Patent Application Publication No. 2004-353460 discloses an internal combustion engine equipped with an in-cylinder injection valve for injecting CNG into the cylinder. CNG refers to compressed natural gas. Summary of the Invention

[0003] [Summary of the Invention]

[0004] [The problem the invention aims to solve]

[0005] Typically, in internal combustion engines that inject gaseous fuels such as CNG into the cylinder via the injection valve, a lower pressure can be set as the fuel supply pressure (fuel pressure) compared to when using liquid fuels such as gasoline. Furthermore, due to abnormal combustion such as early ignition occurring in the cylinder during the compression stroke, the pressure inside the cylinder can sometimes rise excessively. In such cases, the injection valve cannot be maintained in a closed state in internal combustion engines using gaseous fuels such as CNG. Consequently, combustion gases may flow backward into the injection valve. Since the combustion gases inside the cylinder are at high temperatures, a large backflow of combustion gases into the injection valve can cause malfunctions in the injection valve.

[0006] [Solutions for solving the problem]

[0007] In one aspect of this disclosure, an internal combustion engine control device is provided. The internal combustion engine includes a cylinder and an in-cylinder injection valve for injecting gaseous fuel into the cylinder. The internal combustion engine control device includes an actuator that controls the operation of the internal combustion engine. The actuator is configured to perform the following steps: obtaining the cylinder pressure (i.e., cylinder pressure) and the pressure of the gaseous fuel supplied to the in-cylinder injection valve (i.e., supply fuel pressure) during one combustion cycle of the cylinder; and calculating the amount of combustion gas flowing from the cylinder into the in-cylinder injection valve (i.e., reverse flow rate) during one combustion cycle of the cylinder, wherein the reverse flow rate is calculated such that the higher the cylinder pressure, the greater the reverse flow rate, and the lower the supply fuel pressure, the greater the reverse flow rate.

[0008] In another aspect of this disclosure, an internal combustion engine control method is provided. The internal combustion engine includes a cylinder and an in-cylinder injection valve for injecting gaseous fuel into the cylinder. The internal combustion engine control method includes the following steps: obtaining the cylinder pressure (i.e., cylinder pressure) and the pressure of the gaseous fuel supplied to the in-cylinder injection valve (i.e., supply fuel pressure) during one combustion cycle of the cylinder; calculating the amount of combustion gas flowing from the cylinder into the in-cylinder injection valve during one combustion cycle (i.e., reverse flow rate), and calculating the reverse flow rate in a manner that the higher the cylinder pressure, the greater the reverse flow rate, and the lower the supply fuel pressure, the greater the reverse flow rate. Attached Figure Description

[0009] Figure 1 This is a schematic configuration diagram showing the control device and the internal combustion engine to which the control device is applied, according to a first embodiment of the internal combustion engine control device.

[0010] exist Figure 2 In the diagram, (A) is a cross-sectional view of the in-cylinder injection valve of the aforementioned internal combustion engine, and (B) is an enlarged view of a portion of the in-cylinder injection valve.

[0011] Figure 3 This is a block diagram illustrating multiple processes executed by the control device of the first embodiment.

[0012] Figure 4 It is a coordinate graph showing the relationship between the actual amount of combustion gas flowing from the cylinder into the cylinder injection valve, i.e., the actual reverse flow rate, and the reverse flow rate calculated by the control device of the first embodiment.

[0013] Figure 5 This is a graph showing the shift of the cumulative reverse flow value calculated by the control device of the first embodiment.

[0014] Figure 6 This is a flowchart illustrating the cumulative processing performed by the control device in the second embodiment of the internal combustion engine control device.

[0015] Figure 7 This is a block diagram representing multiple processes performed by the control device in the third embodiment of the internal combustion engine control device.

[0016] Figure 8 This is a flowchart illustrating the cumulative processing performed by the control device of the third embodiment. Detailed Implementation

[0017] (First Implementation)

[0018] The following shall be in accordance with Figures 1-5 This describes the first embodiment of the internal combustion engine control device.

[0019] Figure 1The figure shows an internal combustion engine 10 mounted on a vehicle and a control device 60 adapted to the internal combustion engine 10. The control device 60 corresponds to "internal combustion engine control device".

[0020] Internal Combustion Engine

[0021] The internal combustion engine 10 is a hydrogen engine that uses hydrogen as fuel. Hydrogen corresponds to "gaseous fuel". The internal combustion engine 10 has multiple cylinders 11, a crankshaft 12, an intake passage 13, a throttle valve 14, and an exhaust passage 15. Figure 1 In the example shown, the internal combustion engine 10 has four cylinders 11. In this specification, when referring to the four cylinders collectively, they are referred to as "cylinder 11", and when referring to them separately, they are referred to as cylinder #1, cylinder #2, cylinder #3 and cylinder #4.

[0022] The intake passage 13 is a passage for airflow into multiple cylinders 11. A throttle valve 14 is located in the intake passage 13. The amount of air flowing in the intake passage 13, i.e., the intake air volume, is adjusted by adjusting the opening of the throttle valve 14, i.e., the throttle valve opening.

[0023] The internal combustion engine 10 includes multiple in-cylinder injection valves 16 and multiple ignition devices 17. One in-cylinder injection valve 16 and one ignition device 17 are provided for each cylinder 11. The in-cylinder injection valves 16 inject fuel into the cylinder 11. The structure of the in-cylinder injection valves 16 will be described later. Within the multiple cylinders 11, combustion gases containing air and fuel are burned by the discharge of the ignition device 17. The power obtained from the combustion of the combustion gases is transmitted to the crankshaft 12, thereby rotating the crankshaft 12. Exhaust gases are generated within the multiple cylinders 11 through the combustion of the combustion gases. These exhaust gases are discharged from the multiple cylinders 11 into the exhaust passage 15.

[0024] The internal combustion engine 10 has a fuel supply device 20 that supplies fuel to multiple in-cylinder injection valves 16. The fuel supply device 20 includes a fuel tank 21, a fuel supply passage 22, a pressure regulating device 23, and a delivery pipe 24.

[0025] Fuel tank 21 stores high-pressure fuel. Fuel supply passage 22 is a passage for supplying the fuel stored in fuel tank 21 to delivery pipe 24. Pressure regulating device 23 is provided in the middle of fuel supply passage 22. Pressure regulating device 23 is a structure that reduces the pressure of fuel flowing in fuel supply passage 22 by means of control based on control device 60. Therefore, the pressure of the portion of fuel flowing in fuel supply passage 22 between pressure regulating device 23 and delivery pipe 24 is lower than the pressure of the portion of fuel flowing in fuel supply passage 22 between pressure regulating device 23 and fuel tank 21.

[0026] Multiple in-cylinder injection valves 16 are connected to the delivery pipe 24. That is, the delivery pipe 24 temporarily stores the fuel supplied to the multiple in-cylinder injection valves 16. The pressure of the fuel in the delivery pipe 24 corresponds to the pressure of the fuel supplied to the in-cylinder injection valves 16, i.e., the "supply pressure".

[0027] Reference Figure 2 A and Figure 2 B, describes the structure of the in-cylinder injection valve 16.

[0028] like Figure 2 A and Figure 2 As shown in Figure B, the in-cylinder injection valve 16 has a body 41, a seat 42, a needle 43, a spring 44, and an electromagnetic coil 45. The body 41 is cylindrical. The seat 42 is held at the front end 411 of the body 41. An injection port 46 for injecting fuel into the cylinder 11 is formed on the seat 42.

[0029] The needle 43 is housed within the body 41 in a state that allows it to move towards and away from the seat 42. When the needle 43 is seated on the valve seat of the seat 42, the injection port 46 is closed. The needle 43 corresponds to the "valve core of the in-cylinder injection valve". The state in which the in-cylinder injection valve 16 has its injection port 46 closed is called "in-cylinder injection valve 16 closed". On the other hand, in the case of Figure 2 When needle 43 as shown in B separates from the valve seat of seat 42, injection port 46 is opened. The state of the in-cylinder injection valve 16 with injection port 46 open is called "in-cylinder injection valve 16 open".

[0030] An internal fuel passage 47 for fuel flow is formed between the inner circumferential surface of the main body 41 and the needle 43. The internal fuel passage 47 is connected to the delivery pipe 24. When the in-cylinder injection valve 16 opens, the internal fuel passage 47 connects to the injection port 46. At this time, if the pressure in the internal fuel passage 47 is higher than the pressure inside the cylinder 11, then... Figure 2 As indicated by the solid arrow in B, fuel is injected from the injection port 46 into the cylinder 11.

[0031] Spring 44 exerts a force on needle 43 in the direction that presses needle 43 against seat 42. That is, when the injection valve 16 is closed, the greater the force of spring 44, the greater the force pressing needle 43 against seat 42. When the solenoid coil 45 is energized, an electromagnetic force is generated in the direction that causes needle 43 to separate from seat 42. Thus, the force of spring 44 pressing needle 43 against seat 42 is overcome, and needle 43 separates from seat 42. As a result, injection valve 16 opens. On the other hand, when the energization of solenoid coil 45 is stopped, the force of spring 44 presses needle 43 against seat 42. As a result, injection valve 16 closes.

[0032] The force by which the needle 43 is pressed against the seat 42 by the spring 44 when the in-cylinder injection valve 16 is closed is set as the "adjustment load". The adjustment load is set to the extent that the needle 43 can maintain its position on the valve seat 42 under normal combustion conditions in the cylinder 11. That is, when the energization to the solenoid coil 45 is stopped, if there is no abnormal combustion such as premature ignition in the cylinder 11, the needle 43 can maintain its position on the valve seat 42. In other words, if the pressure in the cylinder 11 rises excessively due to abnormal combustion as described above, the needle 43 may move in a direction that separates from the seat 42, overcoming the fuel pressure supplied to the in-cylinder injection valve 16 and the adjustment load. In this case, the needle 43 separates from the seat 42, and therefore the injection port 46 is not blocked.

[0033] Internal Combustion Engine Testing System

[0034] like Figure 1 As shown, the internal combustion engine 10 includes a detection system 50 for detecting the state of the internal combustion engine 10. The detection system 50 has multiple sensors. The multiple sensors output signals corresponding to the detection results to the control device 60. The multiple sensors include a crankshaft angle sensor 51, an in-cylinder pressure sensor 52 (the same number as the number of cylinders), and a fuel supply pressure sensor 53. One in-cylinder pressure sensor 52 is provided for each cylinder 11.

[0035] Crankshaft angle sensor 51 detects the rotation angle of crankshaft 12. Cylinder pressure sensor 52 detects the pressure inside the corresponding cylinder 11. Fuel pressure sensor 53 detects the fuel pressure inside the delivery pipe 24. The rotational speed of crankshaft 12 based on the detection value of crankshaft angle sensor 51 is called "engine speed NE". The pressure inside cylinder 11 based on the detection value of cylinder pressure sensor 52 is called "cylinder pressure detection value PCYS". The fuel pressure inside the delivery pipe 24 based on the detection value of fuel pressure sensor 53 is called "fuel pressure detection value PDS".

[0036] <Control Device>

[0037] The control unit 60 is a processing circuit with a CPU 61 and a memory 62. The memory 62 stores various control programs that are executed by the CPU 61. By executing the control programs, the CPU 61 controls the opening of the throttle valve 14, the fuel injection quantity of the in-cylinder injection valve 16, and the ignition timing of the ignition device 17 based on signals from multiple sensors. In the control unit 60, the CPU 61 corresponds to the "execution unit".

[0038] The vehicle is equipped with a warning device 70. In the event of an abnormality in the internal combustion engine 10, the warning device 70 operates to notify the passengers of the abnormality in the internal combustion engine 10.

[0039] like Figure 3 As shown, CPU61 executes the acquisition process M11, the reverse flow calculation process M13, the accumulation process M15, and the notification process M17 by executing the control program.

[0040] <Obtain Processing>

[0041] In processing M11, CPU 61 obtains the information required for reverse flow calculation processing M13. Specifically, CPU 61 obtains the pressure inside cylinder 11 during one combustion cycle, i.e., the cylinder pressure PCY, and the pressure of fuel supplied from delivery pipe 24 to cylinder injection valve 16, i.e., the fuel supply pressure PD. Furthermore, CPU 61 obtains the engine speed NEA. Additionally, CPU 61 obtains the fuel injection termination time TIE of cylinder injection valve 16.

[0042] CPU61 obtains the cylinder pressure PCY(N) of cylinder #N in one combustion cycle. "N" is the cylinder number, which can be any one of 1, 2, 3, or 4. That is, CPU61 obtains the cylinder pressure PCY(1) of cylinder #1 in one combustion cycle. CPU61 obtains the cylinder pressure PCY(2) of cylinder #2 in one combustion cycle. CPU61 obtains the cylinder pressure PCY(3) of cylinder #3 in one combustion cycle. CPU61 obtains the cylinder pressure PCY(4) of cylinder #4 in one combustion cycle.

[0043] Specifically, the CPU61 obtains the in-cylinder pressure PCY(N) of cylinder #N in one combustion cycle based on multiple in-cylinder pressure detection values ​​PCYS detected in one combustion cycle of cylinder #N. For example, the CPU61 obtains the maximum value among the multiple in-cylinder pressure detection values ​​PCYS detected in one combustion cycle of cylinder #N as the in-cylinder pressure PCY(N) of cylinder #N in one combustion cycle.

[0044] CPU61 obtains the supply fuel pressure PD(N) of cylinder #N in one combustion cycle. That is, CPU61 obtains the supply fuel pressure PD(1) of cylinder #1 in one combustion cycle. CPU61 obtains the supply fuel pressure PD(2) of cylinder #2 in one combustion cycle. CPU61 obtains the supply fuel pressure PD(3) of cylinder #3 in one combustion cycle. CPU61 obtains the supply fuel pressure PD(4) of cylinder #4 in one combustion cycle.

[0045] Specifically, the CPU61 obtains the supply fuel pressure PD(N) of cylinder #N in one combustion cycle based on multiple supply fuel pressure detection values ​​PDS detected in one combustion cycle of cylinder #N. For example, the CPU61 obtains the average value of multiple supply fuel pressure detection values ​​PDS detected in one combustion cycle of cylinder #N as the supply fuel pressure PD(N) of cylinder #N in one combustion cycle.

[0046] CPU61 obtains the engine speed NEA(N) during one combustion cycle of cylinder #N. That is, CPU61 obtains the engine speed NEA(1) during one combustion cycle of cylinder #1. CPU61 obtains the engine speed NEA(2) during one combustion cycle of cylinder #2. CPU61 obtains the engine speed NEA(3) during one combustion cycle of cylinder #3. CPU61 obtains the engine speed NEA(4) during one combustion cycle of cylinder #4.

[0047] Specifically, the CPU61 obtains the engine speed NEA(N) in one combustion cycle of cylinder #N based on multiple engine speeds NE detected in one combustion cycle of cylinder #N. For example, the CPU61 obtains the average value of multiple engine speeds NE detected in one combustion cycle of cylinder #N as the engine speed NEA(N) in one combustion cycle of cylinder #N.

[0048] CPU 61 obtains the end time of energizing the solenoid coil 45 of the cylinder injection valve 16 as the end time TIE(N) of fuel injection for cylinder #N. That is, CPU 61 obtains the end time TIE(1) of fuel injection for cylinder #1. CPU 61 obtains the end time TIE(2) of fuel injection for cylinder #2. CPU 61 obtains the end time TIE(3) of fuel injection for cylinder #3. CPU 61 obtains the end time TIE(4) of fuel injection for cylinder #4.

[0049] <Reverse Flow Calculation and Processing>

[0050] In the reverse flow calculation process M13, CPU61 calculates the amount of combustion gas flowing from cylinder #N into the in-cylinder injection valve 16 during one combustion cycle of cylinder #N, i.e., the reverse flow QR(N). That is, CPU61 calculates the reverse flow QR(1) in one combustion cycle of cylinder #1. CPU61 obtains the reverse flow QR(2) in one combustion cycle of cylinder #2. CPU61 obtains the reverse flow QR(3) in one combustion cycle of cylinder #3. CPU61 obtains the reverse flow QR(4) in one combustion cycle of cylinder #4.

[0051] Here, during the compression stroke of cylinder #N, CPU 61 injects fuel from the in-cylinder injection valve 16 for cylinder #N. The hydrogen injected by the in-cylinder injection valve 16 as fuel has a lower fuel density than liquid fuels such as gasoline. Therefore, in the internal combustion engine 10 that uses hydrogen as fuel, the end of fuel injection by the in-cylinder injection valve 16 is generally more likely to be delayed compared to the case of an internal combustion engine that uses liquid fuel.

[0052] If the pressure inside cylinder #N rises excessively due to abnormal combustion such as early ignition, the pressure inside cylinder #N may sometimes be higher than the pressure inside the injection valve 16. Early ignition is prone to occur during the compression stroke of cylinder #N. If the injection valve 16 is energized during such abnormal combustion, such as... Figure 2 As indicated by the dashed arrow at point B, combustion gases in cylinder #N may flow into the in-cylinder injection valve 16 via injection port 46. Furthermore, even if the energization of the in-cylinder injection valve 16 has ceased during abnormal combustion, if the pressure in cylinder #N is greater than the sum of the supplied fuel pressure and the set load, needle 43 may sometimes detach from the valve seat 42 due to the pressure within cylinder #N. In situations where the in-cylinder injection valve 16 cannot be maintained in a closed state, such as… Figure 2 As indicated by the dashed arrow in B, combustion gases in cylinder #N may flow into the in-cylinder injection valve 16 via injection port 46.

[0053] When the abnormal combustion described above causes the injection valve 16 to remain open, the higher the pressure in cylinder #N, the greater the pressure difference between cylinder #N and the injection valve 16. Therefore, the amount of combustion gas flowing from cylinder #N into the injection valve 16 increases. Furthermore, the lower the fuel pressure supplied to the injection valve 16, the greater the pressure difference between cylinder #N and the injection valve 16. In this case, the amount of combustion gas flowing from cylinder #N into the injection valve 16 also increases. Moreover, the lower the engine speed, the longer the duration of the open state of the injection valve 16 due to excessive pressure in cylinder #N tends to be. In this case, the longer this duration, the greater the amount of combustion gas flowing from cylinder #N into the injection valve 16. Furthermore, the later the fuel injection ends at the injection valve 16, the longer the period during which combustion gas flows from cylinder #N into the injection valve 16. In this case, the longer the inflow period, the more combustion gas flows from cylinder #N into the cylinder injection valve 16.

[0054] Therefore, in the reverse flow calculation process M13, CPU 61 calculates the reverse flow QR(N) based on the principle that the higher the in-cylinder pressure PCY(N) in one combustion cycle of cylinder #N, the greater the reverse flow. CPU 61 calculates the reverse flow QR(N) based on the principle that the lower the supply fuel pressure PD(N) in one combustion cycle of cylinder #N, the greater the reverse flow. CPU 61 calculates the reverse flow QR(N) based on the principle that the lower the engine speed NEA(N) in one combustion cycle of cylinder #N, the greater the reverse flow. CPU 61 calculates the reverse flow QR(N) based on the principle that the later the fuel injection end time TIE(N) of the in-cylinder injection valve 16 used for cylinder #N, the greater the reverse flow.

[0055] For example, CPU61 calculates the reverse flow rate QR using the following formula (D1). In formula (D1), "F1", "F2", "F3", and "F4" are coefficients set based on the shape of cylinder 11 and the characteristics of the in-cylinder injection valve 16. For example, multiple coefficients F1, F2, F3, and F4 are set such that the larger the design value of the set load of the in-cylinder injection valve 16, the smaller the reverse flow rate QR.

[0056] QR=F1×PCY-F2×PD-F3×NEA-F4×TIE…(D1)

[0057] Figure 4 This is a coordinate graph representing the relationship between the actual reverse flow rate (actual reverse flow) and the calculated reverse flow rate QR using the above formula (D1). This is to ensure that the approximate formula E1 representing the relationship between the actual reverse flow rate and the reverse flow rate QR is accurate. Figure 4 The function is represented by dashed lines and has multiple coefficients F1, F2, F3, and F4.

[0058] By calculating the amount of combustion gas flowing into the cylinder injection valve 16 for cylinder #N during one combustion cycle, i.e., the reverse flow rate QR(N), the CPU 61 substitutes the cylinder pressure PCY(N), the fuel supply pressure PD(N), the engine speed NEA(N), and the fuel injection end time TIE into the above relationship (D1). Thus, the CPU 61 can calculate the reverse flow rate QR(N).

[0059] However, if no abnormal combustion such as early ignition occurs during one combustion cycle of cylinder #N, the pressure inside cylinder #N will not rise excessively. Therefore, if the energization to the in-cylinder injection valve 16 is stopped, the in-cylinder injection valve 16 can be kept closed. That is, during one combustion cycle of cylinder #N, the combustion gases inside cylinder #N do not flow into the in-cylinder injection valve 16. Therefore, the CPU 61 determines whether abnormal combustion such as early ignition has occurred in cylinder #N according to each combustion cycle. For example, the CPU 61 can determine whether abnormal combustion has occurred based on the shift of the in-cylinder pressure detection value PCYS during one combustion cycle of cylinder #N. If abnormal combustion is determined to have occurred, the CPU 61 calculates the reverse flow rate QR(N) by executing the reverse flow calculation process M13. On the other hand, if abnormal combustion is determined not to have occurred, the CPU 61 does not execute the reverse flow calculation process M13, and therefore does not calculate the reverse flow rate QR(N).

[0060] <Cumulative Processing>

[0061] like Figure 3 As shown, in the cumulative processing M15, CPU 61 accumulates the reverse flow QR calculated by the reverse flow calculation processing M13 according to each cylinder 11. That is, CPU 61 accumulates the reverse flow QR (1) into the in-cylinder injection valve 16 used for cylinder #1 to calculate the cumulative reverse flow value IQR (1). CPU 61 accumulates the reverse flow QR (2) into the in-cylinder injection valve 16 used for cylinder #2 to calculate the cumulative reverse flow value IQR (2). CPU 61 accumulates the reverse flow QR (3) into the in-cylinder injection valve 16 used for cylinder #3 to calculate the cumulative reverse flow value IQR (3). CPU 61 accumulates the reverse flow QR (4) into the in-cylinder injection valve 16 used for cylinder #4 to calculate the cumulative reverse flow value IQR (4).

[0062] <Notification Processing>

[0063] In notification processing M17, if the cumulative reverse flow value IQR(N) calculated by cumulative processing M15 is higher than or equal to the judgment value IQRth, CPU61 notifies the passengers of the vehicle. Specifically, if any one of the multiple cumulative reverse flow values ​​IQR(1), IQR(2), IQR(3), IQR(4) is higher than or equal to the judgment value IQRth, CPU61 notifies the passengers via the onboard warning device 70.

[0064] Here, as described above, the temperature of the combustion gases inside cylinder 11 is very high. On the other hand, the temperature of the fuel injected into cylinder 11 from the in-cylinder injection valve 16 is very low compared to the combustion gases. Therefore, if the flow of combustion gases from cylinder 11 into the in-cylinder injection valve 16 is repeated, the heating of the components of the in-cylinder injection valve 16 by the combustion gases and the cooling of those components by the fuel will occur repeatedly. When such repeated heating and cooling of the components occurs, the in-cylinder injection valve 16 may malfunction. For example, the thin film formed on the surface of the needle 43, one of the components of the in-cylinder injection valve 16, may peel off from the needle 43.

[0065] Therefore, in the control device 60, a judgment value IQRth is set as the value used to determine whether there is an abnormality in the components of the in-cylinder injection valve 16 as described above, based on the cumulative reverse flow value IQR(N).

[0066] Figure 5 The graph illustrates the shift of multiple reverse flow cumulative values ​​(IQR). Figure 5 For ease of understanding, only the progression of the three reverse flow cumulative values ​​IQR(1), IQR(2), and IQR(3) is shown in the figure. Figure 5 In the example shown, the cumulative reverse flow values ​​IQR(2) and IQR(3) gradually increase, while the other cumulative reverse flow value IQR(1) does not increase much. At time t11, the cumulative reverse flow value IQR(3) exceeds the judgment value IQRth, so the CPU61 notifies the passenger via the warning device 70 that there is a possibility of an abnormality in the in-cylinder injection valve 16.

[0067] <Function and Effects of the First Embodiment>

[0068] (1-1) As described above, during one combustion cycle of cylinder #N, if abnormal combustion such as early ignition occurs in cylinder #N, the pressure inside cylinder #N will rise excessively. Therefore, combustion gases from cylinder #N may sometimes flow into the cylinder injection valve 16 used for cylinder #N. In this case, the higher the cylinder pressure PCY during one combustion cycle of cylinder #N, the more likely it is that more combustion gases will flow from cylinder #N into the cylinder injection valve 16. Furthermore, the lower the fuel pressure PD(N) supplied to the cylinder injection valve 16, the more likely it is that more combustion gases will flow from cylinder #N into the cylinder injection valve 16.

[0069] Therefore, the control device 60 calculates the reverse flow rate QR(N) based on the principle that the higher the in-cylinder pressure PCY(N), the greater the reverse flow rate, and the lower the supply fuel pressure PD(N), the greater the reverse flow rate. Thus, when abnormal combustion occurs in cylinder #N and the pressure in cylinder #N rises excessively, the amount of combustion gas flowing from cylinder #N into the in-cylinder injection valve 16 during one combustion cycle can be calculated with high precision.

[0070] (1-2) The higher the maximum pressure inside cylinder #N during one combustion cycle, the greater the pressure difference between cylinder #N and the in-cylinder injection valve 16. Therefore, the control device 60 obtains the maximum pressure inside cylinder #N during one combustion cycle as the in-cylinder pressure PCY(N). Furthermore, the control device 60 calculates the reverse flow rate QR(N) based on this in-cylinder pressure PCY(N), thus improving the calculation accuracy of the reverse flow rate QR(N).

[0071] (1-3) When combustion gases flow from cylinder #N into the in-cylinder injection valve 16, the lower the engine speed NEA(N), the more combustion gases flow from cylinder #N into the in-cylinder injection valve 16. Therefore, the control device 60 calculates the reverse flow QR(N) in a way that the lower the engine speed NEA(N), the greater the reverse flow. By considering the engine speed NEA(N) in this way when calculating the reverse flow QR(N), the calculation accuracy of the reverse flow QR(N) can be further improved.

[0072] (1-4) When combustion gases flow from cylinder #N into the in-cylinder injection valve 16, the later the TIE (timing interval) of fuel injection at the in-cylinder injection valve 16, the more combustion gases flow from cylinder #N into the in-cylinder injection valve 16. Therefore, the control device 60 calculates the reverse flow rate QR(N) in a way that the later the TIE, the greater the reverse flow rate. By considering the TIE in this way when calculating the reverse flow rate QR(N), the calculation accuracy of the reverse flow rate QR(N) can be further improved.

[0073] (1-5) The reverse flow rate QR(N) is used as an indicator of the degree of damage accumulated to the cylinder injection valve 16 due to the flow of combustion gases from cylinder #N into the cylinder injection valve 16 during one combustion cycle of cylinder #N. The control device 60 calculates the cumulative reverse flow rate IQR(N) accumulated by the reverse flow rate QR(N). If the cumulative reverse flow rate IQR(N) is higher than or equal to the judgment value IQRth, the components of the cylinder injection valve 16 for cylinder #N may malfunction. Therefore, if the cumulative reverse flow rate IQR(N) is higher than or equal to the judgment value IQRth, the control device 60 notifies the passenger that there is a possibility of an malfunction in the internal combustion engine 10. This allows the passenger to be aware that it is time for the internal combustion engine 10 to be inspected.

[0074] (Second Implementation)

[0075] In accordance with Figure 6 This section describes a second embodiment of the internal combustion engine control device. In this second embodiment, a portion of the cumulative processing content differs from that in the first embodiment. The following description primarily focuses on the differences from the first embodiment; for components identical to those in the first embodiment, the same symbols are used, and repeated descriptions are omitted.

[0076] <Cumulative Processing>

[0077] Reference Figure 6 This describes the cumulative processing M15 executed by the CPU 61 of the control device 60 in this embodiment.

[0078] In step S11, CPU61 determines whether the reverse flow QR(N) calculated by reverse flow calculation process M13 is above the threshold QRth.

[0079] As described above, when combustion gases repeatedly flow into the in-cylinder injection valve 16, the components of the in-cylinder injection valve 16 are repeatedly heated and cooled, thereby accumulating damage in these components. However, the inventors conducted various experiments and simulations, and as a result, obtained the following insights.

[0080] If the amount of combustion gas flowing from cylinder #N into the cylinder injection valve 16 is small, the amount of heat energy transferred from the combustion gas flowing into the cylinder injection valve 16 to the component is small, and therefore the temperature rise of the component is small. Therefore, even if a small amount of combustion gas flows into the cylinder injection valve 16 repeatedly, the temperature fluctuation of the component is not large, and thus the component is hardly damaged.

[0081] Therefore, a threshold value QRth is set as the criterion for determining whether the inflow of combustion gas from cylinder #N into the in-cylinder injection valve 16 is insufficient. If the reverse flow QR(N) is less than the threshold value QRth, it is considered that the components of the in-cylinder injection valve 16 have not been damaged due to the inflow of combustion gas into the in-cylinder injection valve 16. On the other hand, if the reverse flow QR(N) is greater than or equal to the threshold value QRth, it is considered that the components of the in-cylinder injection valve 16 have been damaged due to the inflow of combustion gas into the in-cylinder injection valve 16.

[0082] In step S11, if the reverse flow QR(N) is above the threshold QRth (Yes), CPU 61 proceeds to step S13. On the other hand, if the reverse flow QR(N) is less than the threshold QRth (S11: No), CPU 61 temporarily terminates the accumulation process M15. That is, CPU 61 does not accumulate reverse flows QR(N) less than the threshold QRth.

[0083] In step S13, CPU 61 calculates the sum of the cumulative reverse flow value IQR(N) and the reverse flow QR(N) as the latest value of the cumulative reverse flow value IQR(N). That is, CPU 61 only accumulates the reverse flow QR(N) above the threshold QRth among the multiple reverse flow QR(N) calculated through reverse flow calculation process M13, thereby calculating the cumulative reverse flow value IQR(N). Then, CPU 61 temporarily ends the accumulation process M15.

[0084] <Function and Effects of the Second Embodiment>

[0085] In the second embodiment, in addition to the effects equivalent to those of the first embodiment described above (1-1) to (1-5), the following effects can also be obtained.

[0086] (2-1) Even if combustion gases flow into the in-cylinder injection valve 16, the components of the in-cylinder injection valve 16 will hardly be damaged if the amount is small. Therefore, the control device 60 calculates the cumulative reverse flow value IQR(N) by accumulating only the reverse flow QR(N) above the threshold QRth. As a result, the correlation between the degree of damage accumulation to the components of the in-cylinder injection valve 16 and the cumulative reverse flow value IQR(N) can be improved. Therefore, the control device 60 can notify the passengers of the possibility of an abnormality in the internal combustion engine 10 at a more appropriate time.

[0087] (Third Implementation)

[0088] In accordance with Figure 7 and Figure 8 This section describes a third embodiment of the internal combustion engine control device. In this third embodiment, the method for estimating the degree of accumulated damage to the components of the in-cylinder injection valve differs from the methods described above. In the following description, the differences from the aforementioned embodiments will be primarily explained; for components identical to those in the aforementioned embodiments, the same symbols will be used, and repeated descriptions will be omitted.

[0089] When combustion gases flow into the cylinder injection valve 16 of cylinder 11, heat energy is transferred from the high-temperature combustion gases to the components of the cylinder injection valve 16. The more combustion gases flow from cylinder 11 into the cylinder injection valve 16, the more heat energy is transferred to the components. The more heat energy is transferred to the components, the greater the temperature rise of the components. Furthermore, the higher the internal temperature of cylinder 11, the easier it is for the temperature of the combustion gases to rise. And the higher the temperature of the combustion gases flowing from cylinder 11 into the cylinder injection valve 16, the greater the temperature rise of the components.

[0090] On the other hand, when the in-cylinder injection valve 16 injects fuel into the cylinder 11 due to the valve opening, the fuel flowing within the in-cylinder injection valve 16 removes heat energy from the components. As a result, the temperature of the components decreases.

[0091] That is, due to the temperature fluctuations of the component caused by the heat energy entering and leaving such a component, the film formed on the component will peel off from the component.

[0092] Therefore, the control device 60 of this embodiment calculates a correlation value for the amount of heat energy transferred from the combustion gas flowing from the cylinder 11 into the in-cylinder injection valve 16 to the components of the in-cylinder injection valve 16 during one combustion cycle. Based on the calculated value, the control device 60 calculates a damage index value, i.e., a damage index value, of the damage suffered by the components of the in-cylinder injection valve 16 due to the flow of combustion gas from the cylinder #N into the in-cylinder injection valve 16 during one combustion cycle of cylinder #N. Furthermore, based on the damage index value, the control device 60 estimates the degree of accumulation of damage to the components.

[0093] <Control Device>

[0094] like Figure 7 As shown, CPU 61 executes the acquisition process M11, the reverse flow calculation process M13, the damage index value calculation process M21, the accumulation process M151, and the notification process M171 by executing the control program. The contents of the acquisition process M11 and the reverse flow calculation process M13 are the same as in the first embodiment described above. Therefore, the description of the acquisition process M11 and the reverse flow calculation process M13 is omitted here.

[0095] <Calculation and Processing of Damage Index Values>

[0096] In the damage index value calculation and processing M21, CPU61 calculates the damage index value X for each cylinder 11. That is, CPU61 calculates the damage index value X(1) for the components of the in-cylinder injection valve 16 used in cylinder #1. CPU61 calculates the damage index value X(2) for the components of the in-cylinder injection valve 16 used in cylinder #2. CPU61 calculates the damage index value X(3) for the components of the in-cylinder injection valve 16 used in cylinder #3. CPU61 calculates the damage index value X(4) for the components of the in-cylinder injection valve 16 used in cylinder #4.

[0097] The specific calculation method for the damage index value X(N) is explained below. In the event of abnormal combustion as described above during one combustion cycle of cylinder #N, the damage to the components of the in-cylinder injection valve 16 is the product of the temperature of the combustion gas flowing into the in-cylinder injection valve 16 (i.e., gas temperature) and the amount of energy related to the backflow (i.e., backflow energy). That is, the damage index value X(N) can be calculated using the following formula (D2). In formula (D2), "TMP" is the indicator of the gas temperature. "ENR" is the indicator of the amount of backflow energy. According to formula (D2), the larger the gas temperature indicator TMP, the larger the damage index value X. Furthermore, the larger the backflow energy indicator ENR, the larger the damage index value X.

[0098] X = TMP × ENR…(D2)

[0099] The higher the cylinder pressure PCY, the higher the gas temperature index TMP. Therefore, the value of TMP is calculated using the following formula (D3). In formula (D3), "P0" is the reference pressure in cylinder #N. For example, the maximum pressure in one combustion cycle in cylinder #N when abnormal combustion has not occurred is set as the reference pressure P0.

[0100] TMP = PCY / P0…(D3)

[0101] The larger the squared value of the reverse flow rate QR(N), the larger the index of reverse flow energy ENR. Therefore, the index ENR is calculated using the following formula (D4). In formula (D4), "CSA" is the cross-sectional area of ​​the flow path of combustion gas flowing from cylinder #N into the cylinder injection valve 16. For example, the cross-sectional area of ​​the internal fuel passage 47 of the cylinder injection valve 16 is set as the cross-sectional area CSA of the flow path of combustion gas flowing into the cylinder injection valve 16.

[0102] ENR=QR^2 / CSA^2…(D4)

[0103] Furthermore, by using two relations (D3) and (D4), relation (D2) can be transformed as shown in relation (D5). In relation (D5), "KA" is a constant that can be represented by relation (D6).

[0104] X = PCY × (QR^2) / KA…(D5)

[0105] KA=P0×(CSA^2)…(D6)

[0106] In the damage index calculation process M21, CPU61 calculates the damage index value X(N) using formula (D5). When calculating the damage index value X(N) of the component of the in-cylinder injection valve 16 used in cylinder #N, CPU61 can calculate the damage index value X(N) by substituting the in-cylinder pressure PCY(N) and the reverse flow rate QR(N) into formula (D5). Therefore, CPU61 can calculate the damage index value X(N) in such a way that the larger the product of the squared value of the reverse flow rate QR(N) and the in-cylinder pressure PCY, the larger the damage index value.

[0107] <Cumulative Processing>

[0108] In the cumulative processing M151, CPU61 accumulates the damage index value X calculated by the damage index value calculation processing M21 for each cylinder 11. That is, CPU61 calculates the cumulative damage index value IX(1) by accumulating the damage index values ​​X(1) of the components of the in-cylinder injection valve 16 used in cylinder #1. CPU61 calculates the cumulative damage index value IX(2) by accumulating the damage index values ​​X(2) of the components of the in-cylinder injection valve 16 used in cylinder #2. CPU61 calculates the cumulative damage index value IX(3) by accumulating the damage index values ​​X(3) of the components of the in-cylinder injection valve 16 used in cylinder #3. CPU61 calculates the cumulative damage index value IX(4) by accumulating the damage index values ​​X(4) of the components of the in-cylinder injection valve 16 used in cylinder #4.

[0109] Figure 8 This is a flowchart representing the specific processing content of the cumulative processing of M151.

[0110] In step S21, CPU61 determines whether the damage index value X(N) calculated by damage index value calculation process M21 is above the threshold Xth.

[0111] Even if combustion gases from cylinder #N flow into the cylinder injection valve 16, the temperature of the components of the cylinder injection valve 16 does not rise significantly if the damage index value X is small. Therefore, the temperature fluctuations of the components are not large, and the components are almost undamaged. Therefore, a threshold value QRth is set as the criterion for determining whether damage to the components can be ignored. If the damage index value X(N) is less than the threshold value Xth, the components are considered not to have been damaged by the inflow of combustion gases into the cylinder injection valve 16. On the other hand, if the damage index value X(N) is greater than or equal to the threshold value Xth, the components are considered to have been damaged by the inflow of combustion gases into the cylinder injection valve 16.

[0112] In step S21, if the damage index value X(N) is above the threshold Xth (Yes), CPU 61 proceeds to step S23. On the other hand, if the damage index value X(N) is less than the threshold Xth (S21: No), CPU 61 temporarily terminates the accumulation process M151. That is, CPU 61 does not accumulate damage index values ​​X(N) that are less than the threshold Xth.

[0113] In step S23, CPU 61 calculates the sum of the cumulative damage index value IX(N) and the damage index value X(N) as the latest value of the cumulative damage index value IX(N). That is, CPU 61 only accumulates the damage index values ​​X(N) above the threshold Xth among the multiple damage index values ​​X(N) calculated by damage index value calculation process M21, thereby calculating the cumulative damage index value IX(N). Then, CPU 61 temporarily ends the accumulation process M151.

[0114] <Notification Processing>

[0115] In notification processing M171, if the cumulative damage index value IX(N) calculated by cumulative processing M151 is above the judgment value IXth, CPU61 notifies the passengers of the vehicle. Specifically, if any one of the cumulative damage index values ​​IX(1), IX(2), IX(3), and IX(4) is above the judgment value IXth, CPU61 notifies the passengers through the onboard warning device 70.

[0116] <Function and Effects of the Third Embodiment>

[0117] In the third embodiment, in addition to the effects equivalent to those of the first embodiment described above (1-1) to (1-4), the following effects can also be obtained.

[0118] (3-1) Based on the reverse flow rate QR, the control device 60 calculates the value corresponding to the amount of heat energy transferred from the combustion gas flowing into the cylinder injection valve 16 to the components of the cylinder injection valve 16, i.e., the damage index value X. Furthermore, the control device 60 calculates the cumulative damage index value IX by accumulating these damage index values ​​X. The greater the amount of heat energy, the more likely the damage to the components caused by the flow of combustion gas into the cylinder injection valve 16 will be greater. Therefore, by calculating the cumulative damage index value IX, the degree of damage accumulation to the components can be estimated with high accuracy.

[0119] If the cumulative damage index value IX(N) is higher than or equal to the judgment value IXth, the in-cylinder injection valve 16 for cylinder #N may malfunction. Therefore, when the cumulative damage index value IX(N) reaches or exceeds the judgment value IXth, the control device 60 notifies the passenger that there is a possibility of an malfunction in the internal combustion engine 10. This allows the passenger to be aware that it is time for the internal combustion engine 10 to be inspected.

[0120] (3-2) Even if combustion gases flow into the in-cylinder injection valve 16, the amount of heat energy transferred to the components of the in-cylinder injection valve 16 at this time is small, and the components will hardly be damaged. Therefore, the control device 60 calculates the cumulative damage index value IX(N) by accumulating only the damage index values ​​X(N) above the threshold Xth. As a result, the correlation between the degree of damage accumulation of the components of the in-cylinder injection valve 16 and the cumulative damage index value IX(N) can be improved. Therefore, the control device 60 can notify the passenger of the possibility of an abnormality in the internal combustion engine 10 at a more appropriate time.

[0121] (Example of Change)

[0122] The above-described embodiments can be modified as follows. These embodiments and the following modifications can be combined and implemented within the scope of technical non-contradiction.

[0123] In the above-described embodiments, the CPU 61 can obtain the cylinder pressure PCY(N) as the value corresponding to the cylinder pressure detection value PCYS detected in one combustion cycle of cylinder #N, or it can obtain a value different from the maximum value of the cylinder pressure detection value PCYS detected in one combustion cycle of cylinder #N. For example, the CPU 61 can obtain the second largest cylinder pressure detection value PCYS among the multiple cylinder pressure detection values ​​PCYS detected in one combustion cycle of cylinder #N as the cylinder pressure PCY(N). Moreover, for example, the CPU 61 can obtain the average value of the multiple cylinder pressure detection values ​​PCYS detected in one combustion cycle of cylinder #N as the cylinder pressure PCY(N). Moreover, for example, the CPU 61 can obtain the average value of the multiple cylinder pressure detection values ​​PCYS detected during the compression stroke of cylinder #N as the cylinder pressure PCY(N).

[0124] In the above embodiments, the CPU 61 can obtain a value corresponding to the calculated value of the in-cylinder pressure based on the operating state of the internal combustion engine 10 as the in-cylinder pressure PCY(N).

[0125] In the above-described embodiments, the CPU 61 only needs to obtain the value corresponding to the supply fuel pressure detection value PDS detected in one combustion cycle of cylinder #N as the supply fuel pressure PD(N). It can obtain a value different from the average value of multiple supply fuel pressure detection values ​​PDS detected in one combustion cycle of cylinder #N as the supply fuel pressure PD(N). For example, the CPU 61 can obtain any one of the multiple supply fuel pressure detection values ​​PDS detected in one combustion cycle of cylinder #N as the supply fuel pressure PD(N). Specifically, the CPU 61 can obtain the maximum value of the multiple supply fuel pressure detection values ​​PDS detected in one combustion cycle of cylinder #N as the supply fuel pressure PD(N).

[0126] In the above-described embodiments, the CPU 61 can obtain the engine speed NEA(N) as the value corresponding to the engine speed NE detected in one combustion cycle of cylinder #N, or it can obtain a value different from the average value of multiple engine speeds NE detected in one combustion cycle of cylinder #N. For example, the CPU 61 can obtain any one of the multiple engine speeds NE detected in one combustion cycle of cylinder #N as the engine speed NEA(N). Specifically, the CPU 61 can obtain the maximum value of the multiple engine speeds NE detected in one combustion cycle of cylinder #N as the engine speed NEA(N).

[0127] In the above embodiments, CPU61 can calculate the reverse flow rate QR without considering the end time (TIE) of fuel injection of the in-cylinder injection valve 16.

[0128] In the above-described embodiments, CPU 61 can calculate the reverse flow QR without considering the engine speed NEA.

[0129] In several embodiments, when the internal combustion engine 10 is equipped with a knock sensor, the CPU 61 can determine whether abnormal combustion has occurred in cylinder #N based on the detection value of the knock sensor in one combustion cycle of cylinder #N.

[0130] In the third embodiment, during the cumulative processing M151, the CPU61 can also cumulatively calculate the cumulative damage index value IX for damage index values ​​X that are less than the threshold Xth. In this case, Figure 8 In the cumulative processing M151 shown, the determination in step S21 can be omitted.

[0131] In the first and second embodiments, the CPU 61 may not notify the passenger by the warning device 70 even if the cumulative reverse flow rate (IQR) exceeds the judgment value (IQRth). In this case, the CPU 61 may notify the vehicle sales company or repair shop via an external network that the internal combustion engine 10 requires maintenance.

[0132] In the third embodiment, the CPU 61 may not notify the passenger by the warning device 70 even if the cumulative damage index IX reaches or exceeds the judgment value IXth. In this case, the CPU 61 may notify the vehicle sales company or repair shop via an external network that the internal combustion engine 10 requires maintenance.

[0133] In the first and second embodiments, the CPU 61 notifies the passenger via the onboard warning device 70 when any one of the multiple reverse flow accumulation values ​​IQR(1), IQR(2), IQR(3), and IQR(4) is a judgment value IQRth or higher, but it is not limited to this. For example, the CPU 61 may notify the passenger that it is advisable to replace or repair the cylinder injection valve 16 for cylinder #1 when the reverse flow accumulation value IQR(1) becomes a judgment value IQRth or higher.

[0134] In the third embodiment, the CPU61 notifies the passenger via the onboard warning device 70 when any one of the cumulative damage index values ​​IX(1), IX(2), IX(3), and IX(4) is a judgment value IXth or higher, but it is not limited to this. For example, the CPU61 may notify the passenger that it is advisable to replace or repair the cylinder injection valve 16 for cylinder #1 when the cumulative damage index value IX(1) becomes a judgment value IXth or higher.

[0135] In various embodiments, the number of cylinders of the internal combustion engine to which the control device 60 is applied can be any number other than four. For example, the control device 60 can be applied to an internal combustion engine with one cylinder, an internal combustion engine with three cylinders, or an internal combustion engine with six cylinders.

[0136] In several embodiments, the internal combustion engine for which the control device 60 is applicable only needs to have an in-cylinder injection valve 16 for injecting gaseous fuel into the cylinder 11, and does not need to be an internal combustion engine that uses hydrogen as fuel. For example, the internal combustion engine for which the control device 60 is applicable can be an internal combustion engine that has an in-cylinder injection valve for injecting compressed natural gas into the cylinder 11.

[0137] In several embodiments, the pressure regulating device of the fuel supply device may not be a valve that controls the pressure reduction of the fuel. That is, the pressure regulating device may be a structure with a mechanical valve.

[0138] In several embodiments, the fuel supply device may be a structure with a tank for storing liquid hydrogen. In this case, the fuel supply device is provided with a conversion device capable of converting liquid hydrogen into hydrogen gas along the fuel supply path from the tank to the in-cylinder injection valve 16, thereby enabling the in-cylinder injection valve 16 to inject hydrogen gas.

[0139] The control device 60 is not limited to a structure that includes a CPU and ROM to perform software processing. That is, the control device 60 can be any of the structures described in (a) to (c) below.

[0140] (a) The control device 60 includes one or more processors that perform various processes in accordance with a computer program. The processor includes a CPU and memories such as RAM and ROM. The memories store program code or instructions that constitute the manner in which the CPU performs the processes. Memory, i.e., computer-readable media, includes all usable media that can be accessed by a general-purpose or special-purpose computer.

[0141] (b) The control device 60 has one or more dedicated hardware circuits for performing various processes. Examples of dedicated hardware circuits include, for example, application-specific integrated circuits, i.e., ASICs or FPGAs. It should be noted that ASIC is short for "Application Specific Integrated Circuit," and FPGA is short for "Field Programmable Gate Array."

[0142] (c) The control device 60 has a processor that performs a portion of various processes in accordance with a computer program and dedicated hardware circuitry that performs the remaining processes in the various processes.

Claims

1. An internal combustion engine control device for use in an internal combustion engine mounted in a vehicle, wherein, The internal combustion engine has the following features: Cylinder; and The in-cylinder injection valve injects gaseous fuel into the cylinder. The internal combustion engine control device includes an actuator that controls the operation of the internal combustion engine. The actuator is configured to perform the following steps: The pressure inside the cylinder during one combustion cycle of the cylinder, i.e., the cylinder pressure, and the pressure of the gaseous fuel supplied to the cylinder injection valve, i.e., the supply combustion pressure, are obtained. The amount of combustion gas flowing from the cylinder into the in-cylinder injection valve during one combustion cycle of the cylinder is calculated, i.e., the reverse flow rate. The reverse flow rate is calculated in such a way that the higher the in-cylinder pressure, the greater the reverse flow rate, and the lower the supplied combustion pressure, the greater the reverse flow rate. Calculate the damage index value, which is the index value of the damage to the in-cylinder injection valve caused by the flow of combustion gas in the cylinder into the in-cylinder injection valve during one combustion cycle of the cylinder. The calculated damage index values ​​are accumulated; and If the cumulative value of the calculated damage index exceeds the judgment value, the passengers of the vehicle will be notified. In the step of calculating the damage index value, the damage index value is calculated in such a way that the larger the product of the squared value of the reverse flow rate and the cylinder pressure, the larger the damage index value is.

2. The internal combustion engine control device according to claim 1, wherein, The actuator is configured such that, in the step of accumulating the damage index values, only the damage index values ​​that are above a threshold among the calculated damage index values ​​are accumulated.

3. An internal combustion engine control method for an internal combustion engine mounted in a vehicle, wherein, The internal combustion engine has the following features: Cylinder; and The in-cylinder injection valve injects gaseous fuel into the cylinder. The internal combustion engine control method includes the following steps: The pressure inside the cylinder during one combustion cycle of the cylinder, i.e., the cylinder pressure, and the pressure of the gaseous fuel supplied to the cylinder injection valve, i.e., the supply combustion pressure, are obtained. The amount of combustion gas flowing from the cylinder into the in-cylinder injection valve during one combustion cycle of the cylinder is calculated, i.e., the reverse flow rate. The reverse flow rate is calculated in such a way that the higher the in-cylinder pressure, the greater the reverse flow rate, and the lower the supplied combustion pressure, the greater the reverse flow rate. Calculate the damage index value, which is the index value of the damage to the in-cylinder injection valve caused by the flow of combustion gas in the cylinder into the in-cylinder injection valve during one combustion cycle of the cylinder. The calculated damage index values ​​are accumulated; and If the cumulative value of the calculated damage index exceeds the judgment value, the passengers of the vehicle will be notified. In the step of calculating the damage index value, the damage index value is calculated in such a way that the larger the product of the squared value of the reverse flow rate and the cylinder pressure, the larger the damage index value is.

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