Abnormality determination device for internal combustion engine

Abstract

To determine presence / absence of opening fixation of a fuel injection valve during fuel cut.SOLUTION: An ECU 20 executes fuel cut time ignition processing for causing an ignition device 16 to generate spark discharge during fuel cut for temporarily stopping fuel injection of a fuel injection valve 15. When a rotation fluctuation amount of an internal combustion engine 10 during the execution of the fuel cut time ignition processing is a prescribed opening fixation determination value or greater, the ECU 20 determines occurrence of opening fixation of the fuel injection valve 15.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an abnormality determination device for an internal combustion engine. [Background technology]

[0002] Patent Document 1 describes an abnormality determination device for an internal combustion engine equipped with a fuel injection valve that injects gaseous fuel. This abnormality determination device determines whether the fuel injection valve is stuck open based on a pressure change in the fuel supply path after the supply of gaseous fuel to the fuel injection valve begins when the internal combustion engine is started. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-250141 Summary of the Invention [Problem to be solved by the invention]

[0004] The above-described conventional abnormality determination device can determine whether or not the fuel injection valve is stuck open only when the internal combustion engine is started. [Means for solving the problem]

[0005] An abnormality determination device for an internal combustion engine that solves the above problem is an abnormality determination device for an internal combustion engine that includes a fuel injection valve that injects fuel into the intake air and an ignition device that generates a spark discharge to ignite a mixture of the fuel injected by the fuel injection valve and the intake air, and is configured to perform a fuel cut ignition process that generates a spark discharge in the ignition device while a fuel cut is being performed, which temporarily suspends fuel injection from the fuel injection valve while the internal combustion engine is rotating, and an open sticking determination process that determines that the fuel injection valve has become stuck open when the amount of rotational fluctuation of the internal combustion engine during the fuel cut ignition process is greater than or equal to a predetermined open sticking determination value. [Effects of the Invention]

[0006] It is possible to determine whether the fuel injection valve is stuck open while a fuel cut is being performed. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a diagram schematically illustrating the configuration of an embodiment of an abnormality determination device for an internal combustion engine; [Figure 2] 3 is a flowchart of a sticking determination routine executed by the abnormality determination device. DETAILED DESCRIPTION OF THE INVENTION

[0008] An embodiment of an abnormality determination device for an internal combustion engine will be described in detail below with reference to Figures 1 and 2. The abnormality determination device of this embodiment is applied to an internal combustion engine 10 for vehicle use that uses hydrogen gas, which is a type of gaseous fuel, as fuel.

[0009] <Configuration of the embodiment> As shown in FIG. 1, an internal combustion engine 10 to which the abnormality determination device of this embodiment is applied includes an intake passage 11, a combustion chamber 12, and an exhaust passage 13. The internal combustion engine 10 has multiple cylinders, each of which is provided with a combustion chamber 12. FIG. 1 shows only one of the multiple combustion chambers 12. A throttle valve 14 is installed in the intake passage 11 of the internal combustion engine 10. The throttle valve 14 adjusts the amount of intake air introduced into the combustion chamber 12 by changing the flow path area of ​​the intake air in the intake passage 11. The intake passage 11 branches downstream of the throttle valve 14 toward the combustion chamber 12 of each cylinder. The internal combustion engine 10 also includes a fuel injection valve 15 and an ignition device 16 for each cylinder. The fuel injection valve 15 is configured to inject hydrogen gas into the intake air into the combustion chamber 12 in response to a valve opening, and to stop injection of hydrogen gas in response to a valve closing. The ignition device 16 generates a spark discharge to ignite the air-fuel mixture in the combustion chamber 12. The air-fuel mixture is composed of hydrogen gas injected by the fuel injection valve 15 and intake air introduced into the combustion chamber 12 through the intake passage 11. Furthermore, the internal combustion engine 10 has a crankshaft 17, which rotates in response to the combustion of the air-fuel mixture in the combustion chamber 12, as a power takeoff shaft.

[0010] The internal combustion engine 10 is controlled by an ECU (electronic control unit) 20. The ECU 20 includes a storage device 21 and a processing circuit 22. The storage device 21 stores programs and data for controlling the internal combustion engine 10 in advance. The processing circuit 22 executes various processes related to the control of the internal combustion engine 10 by executing the programs read from the storage device 21. The ECU 20 is connected to various sensors for checking the operating state of the internal combustion engine 10. These sensors include a crank angle sensor 23 and a water temperature sensor 24. The crank angle sensor 23 detects the crank angle, which is the rotation angle of the crankshaft 17. The water temperature sensor 24 detects the engine water temperature, which is the temperature of the cooling water for the internal combustion engine 10. The ECU 20 controls the operating state of the internal combustion engine 10 by manipulating the opening of the throttle valve 14, the timing and amount of fuel injection from the fuel injection valve 15, the timing of spark discharge from the ignition device 16, etc.

[0011] When the vehicle is decelerating, the ECU 20 performs a fuel cut to temporarily suspend fuel injection from the fuel injection valve 15. In the case of a normal fuel cut, the ECU 20 stops spark discharge from the ignition device 16 together with stopping fuel injection.

[0012] <Adhesion judgment> The ECU 20 determines whether the fuel injection valve 15 is stuck during operation of the internal combustion engine 10. In this embodiment, the ECU 20 corresponds to an abnormality determination device.

[0013] 2 shows a flowchart of a sticking determination routine executed by the ECU 20. After the internal combustion engine 10 is started, the ECU 20 repeatedly executes the processing of this routine at predetermined control intervals.

[0014] When this routine starts, the ECU 20 first determines in step S100 whether or not the preconditions for the sticking determination are met. The preconditions are that the crank angle sensor 23 used for the determination is normal, that the internal combustion engine 10 has been warmed up, etc. If the preconditions are not met (S100: NO), the ECU 20 ends the current processing of this routine.

[0015] If the precondition is met (S100: YES), the ECU 20 determines whether or not a fuel cut is being performed in step S110. If a fuel cut is being performed (YES), the ECU 20 proceeds to step S120, and if not (NO), the ECU 20 proceeds to step S170.

[0016] If a fuel cut is being performed and the process proceeds to step S120, the ECU 20 commands the ignition device 16 to generate a spark discharge in step S120. As a result, the internal combustion engine 10 is in a state where the fuel injection valve 15 is commanded to stop fuel injection, but the ignition device 16 is commanded to generate a spark discharge. The ECU 20 measures the amount of rotation fluctuation of the internal combustion engine 10 while a fuel cut is being performed with the ignition device 16 generating a spark discharge (S130). Thereafter, in step S140, the ECU 20 determines whether the measured amount of rotation fluctuation is equal to or greater than a predetermined stuck-open valve determination value X. If the amount of rotation fluctuation is equal to or greater than the stuck-open valve determination value X (S140: YES), the ECU 20 determines that the fuel injection valve 15 is stuck-open (S150). On the other hand, if the rotation fluctuation amount is less than the stuck-open determination value X (S140: NO), the ECU 20 determines that the fuel injector 15 has not been stuck-open (S160). After the determinations in steps S150 and S160, the ECU 20 ends the processing of this routine for the current control cycle. Note that stuck-open refers to an abnormality in the fuel injector 15 that makes it unable to close due to foreign matter or the like. When stuck-open occurs, fuel continues to leak from the fuel injector 15 into the combustion chamber 12 even when no injection command is issued.

[0017] On the other hand, if fuel cut is not being performed and the process proceeds to step S170, the ECU 20 determines in step S170 whether the vehicle is in steady running. Specifically, the ECU 20 determines that the vehicle is in steady running if the vehicle speed is equal to or greater than a certain speed and the amount of change in the vehicle speed is within a certain value for a predetermined period of time or more. If the vehicle is not in steady running (S170: NO), the ECU 20 ends the process of this routine for the current control cycle.

[0018] On the other hand, if the vehicle is running steadily (S170: YES), the ECU 20 measures the rotation fluctuation amount of the internal combustion engine 10 (S180). Next, in step S190, the ECU 20 determines whether the rotation fluctuation amount is equal to or greater than a predetermined stuck-closed state determination value Y. If the rotation fluctuation amount is equal to or greater than the stuck-closed state determination value Y (S190: YES), the ECU 20 determines that the fuel injection valve 15 is stuck-closed (S200). If the rotation fluctuation amount is less than the stuck-closed state determination value Y (S190: NO), the ECU 20 determines that the fuel injection valve 15 is not stuck-closed (S210). After the determinations in steps S200 and S210, the ECU 20 ends the processing of this routine for the current control cycle. Stuck-closed state refers to an abnormality in the fuel injection valve 15 that prevents the valve from opening beyond a certain degree due to foreign matter or the like. When the stuck-close state occurs, the amount of fuel injected by the fuel injection valve 15 may fall short of the amount commanded by the ECU 20.

[0019] <Actions and Effects of the Embodiment> 2, the ECU 20 performs a fuel cut ignition process (S120) to generate a spark discharge in the ignition device 16 during a fuel cut that temporarily stops fuel injection from the fuel injection valve 15. Furthermore, the ECU 20 performs an open sticking determination process (S140 to S160) to determine that the fuel injection valve 15 is stuck open when the rotation fluctuation amount of the internal combustion engine 10 during the fuel cut ignition process is equal to or greater than a predetermined open sticking determination value X.

[0020] If the fuel injection valve 15 is not stuck open, fuel injection is not performed, and therefore combustion does not occur even if the ignition device 16 generates a spark discharge. On the other hand, if the fuel injection valve 15 is stuck open, fuel leaks into the combustion chamber 12 even during fuel cut. At this time, if the ignition device 16 generates a spark discharge, the fuel leaked from the fuel injection valve 15 is burned. The torque generated by the combustion increases the rotation speed of the crankshaft 17. Therefore, if the fuel injection valve 15 is stuck open, the amount of rotational fluctuation of the internal combustion engine 10 during the ignition process at the time of fuel cut is larger than if the fuel injection valve 15 is not stuck open. Therefore, the stuck open state determination process described above makes it possible to determine whether the fuel injection valve 15 is stuck open during fuel cut.

[0021] In addition, in the sticking determination routine of FIG. 2, the ECU 20 performs a stuck-on-close determination process in which it determines that the fuel injection valve 15 is stuck on the closed position when the rotational fluctuation amount of the internal combustion engine 10 during combustion operation is equal to or greater than a predetermined stuck-on-close determination value Y (S190 to S210). The combustion operation of the internal combustion engine 10 refers to a state in which the fuel injection valve 15 injects fuel and the ignition device 16 generates a spark discharge, thereby causing combustion in the combustion chamber 12. A stuck-on-close state may occur in one of the fuel injection valves 15 of the multiple combustion chambers 12 of the internal combustion engine 10. The fuel injection amount of the fuel injection valve 15 in which the stuck-on-close state occurs is smaller than the fuel injection amounts of the fuel injection valves 15 of the other cylinders. As a result, the torque generated by combustion in the cylinder in which the stuck-on-closed fuel injection valve 15 is installed is smaller than that of the other cylinders. Therefore, when the fuel injection valve 15 is stuck on the closed position, the rotational fluctuation amount of the internal combustion engine 10 during combustion operation is larger than when the stuck-on-closed state does not occur. Therefore, by the above-described stuck-closed state determination process, it is possible to determine whether or not the fuel injection valve 15 is stuck-closed.

[0022] <Other embodiments> This embodiment can be modified as follows: This embodiment and the following modifications can be combined and implemented within the scope of technical compatibility.

[0023] The stuck-closed determination process may not be performed in the stuck-close determination routine of Fig. 2. Specifically, the processes of steps S170 to S210 in the stuck-close determination routine may be omitted.

[0024] The determination of stuck open status of the fuel injector 15 in the above embodiment can also be applied to internal combustion engines using gaseous fuels other than hydrogen gas or liquid fuel. In internal combustion engines using liquid fuel, the fuel leaking into the combustion chamber from a stuck injector is liquid. However, the leaked fuel may volatilize, forming a flammable mixture in the combustion chamber 12 during fuel cut. Therefore, the stuck open status of the fuel injector can be determined using the stuck open status determination process of the above embodiment even in internal combustion engines using liquid fuel. In internal combustion engines using gaseous fuel, a mixture is formed even without volatilization of fuel, making combustion more likely to occur during ignition processing at the time of fuel cut when the valve is stuck open than in internal combustion engines using liquid fuel. Therefore, the stuck open status of the fuel injector is easier to detect in internal combustion engines using gaseous fuel than in internal combustion engines using liquid fuel using the stuck open status determination process. Furthermore, among gaseous fuels, hydrogen gas has a wider range of flammable air-fuel ratios. Therefore, in an internal combustion engine using hydrogen gas, it is easier to detect a stuck open state of the fuel injection valve in the stuck open state determination process than in the case of an internal combustion engine using other gaseous fuels.

[0025] The abnormality determination device of the above embodiment can also be applied to an internal combustion engine equipped with a fuel injection valve that injects fuel into an intake port. [Explanation of symbols]

[0026] 10 Internal combustion engine 11 Intake passage 12 Combustion chamber 13 Exhaust passage 14 Throttle valve 15 Fuel injection valve 16 Ignition system 17 Crankshaft 20 ECU (abnormality determination device) 21 Storage device 22 Processing circuit 23 Crank angle sensor 24 Water temperature sensor

Claims

1. An abnormality determination device for an internal combustion engine including a fuel injection valve that injects fuel into intake air, and an ignition device that generates a spark discharge to ignite a mixture of the fuel injected by the fuel injection valve and the intake air, a fuel cut ignition process for generating a spark discharge in the ignition device during a fuel cut in which fuel injection from the fuel injection valve is temporarily stopped; a stuck-open state determination process for determining that the fuel injection valve is stuck-open when a rotation fluctuation amount of the internal combustion engine during the fuel cut ignition process is equal to or greater than a predetermined stuck-open state determination value; An abnormality determination device for an internal combustion engine.

2. 2. The abnormality determination device for an internal combustion engine according to claim 1, wherein the fuel is a gaseous fuel.

3. 2. The abnormality determination device for an internal combustion engine according to claim 1, wherein the fuel is hydrogen gas.

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