Internal combustion engine control device

Abstract

To provide an internal combustion engine control device capable of suppressing occurrence of unstable combustion in an internal combustion engine by suppressing an unnecessary increase in speed of the internal combustion engine when an abnormality has occurred in either one of two ignition plugs provided in the internal combustion engine.SOLUTION: In an internal combustion engine control device 50, in the case where one of ignition plugs 10a, 10b is in the normal state and the other of the ignition plugs 10a, 10b is in the abnormal state, an ignition control section 151 stops an ignition operation by one of the ignition plugs 10a, 10b when speed of an internal combustion engine is equal to or higher than second predetermined ignition cut performance speed that is lower than first predetermined ignition cut performance speed. In the case where one of the ignition plugs 10a, 10 is in the normal state and the other of the ignition plugs 10a, 10b is in the abnormal state, a fuel supply control section 152 stops a fuel supply operation to the internal combustion engine when the speed of the internal combustion engine is equal to or higher than second predetermined fuel cut performance speed that is lower than first predetermined fuel cut performance speed.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an internal combustion engine control device that controls the ignition operation of two spark plugs provided for each cylinder of an internal combustion engine mounted on a vehicle, and also controls the fuel injection operation of an injector provided for each cylinder. [Background technology]

[0002] In recent years, internal combustion engines have sometimes adopted a configuration in which multiple spark plugs are provided for one cylinder in order to improve the ignition performance of the mixture generated in the combustion chamber and thereby improve various characteristics such as exhaust gas characteristics and fuel consumption characteristics.

[0003] Under these circumstances, Patent Document 1 discloses a configuration for an ignition timing control device for an internal combustion engine, which, when measuring the operating state of an internal combustion engine equipped with multiple spark plugs in each cylinder to determine and control the ignition timing, selectively cuts off the ignition output or selectively changes the ignition timing from a reference value, diagnoses abnormalities in the ignition system based on the combustion state of the internal combustion engine at that time, and adjusts the ignition timing according to the diagnosis results. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 7-208314 Summary of the Invention [Problem to be solved by the invention]

[0005] However, according to the inventor's investigation, although Patent Document 1 discloses a configuration in which an ignition system abnormality is diagnosed based on the combustion state of the internal combustion engine and the like and ignition timing is adjusted in accordance with the diagnosis result, if the driver tries to forcefully increase the rotation speed of the internal combustion engine by operating the accelerator operation member in the opening direction to compensate for the decrease in output of the internal combustion engine when an abnormality occurs in the ignition plug, the combustion state of the internal combustion engine is likely to become unstable, and there is room for improvement. Also, from the viewpoint of protecting the internal combustion engine mechanism and the catalyst, which are accessories of the internal combustion engine, a configuration is sometimes adopted in which ignition cut control or fuel cut control is executed to prohibit ignition operation or fuel injection operation for the internal combustion engine when the rotation speed of the internal combustion engine exceeds a predetermined rotation speed. However, there is also room for investigation into a practical configuration in such a configuration to prevent the combustion state of the internal combustion engine from becoming unstable when an abnormality occurs in the ignition plug.

[0006] The present invention was made after considering the above-mentioned considerations, and aims to provide an internal combustion engine control device that can prevent the engine speed from increasing unnecessarily when an abnormality occurs in only one of the two spark plugs provided in the internal combustion engine, maintain the engine speed within an appropriate range, and suppress the occurrence of unstable combustion in the internal combustion engine. [Means for solving the problem]

[0007] In order to achieve the above object, the present invention provides an internal combustion engine control device including an ignition control unit that controls ignition operations by first and second spark plugs provided for one cylinder of an internal combustion engine, and a fuel supply control unit that controls a supply operation of fuel to the internal combustion engine, The ignition control unit stops the ignition operation by the first spark plug and the second spark plug when the rotation speed of the internal combustion engine is equal to or higher than a first predetermined ignition cut rotation speed when both the first spark plug and the second spark plug are in a normal state, and stops the ignition operation by one of the first spark plug and the second spark plug when the rotation speed of the internal combustion engine is equal to or higher than a second predetermined ignition cut rotation speed that is lower than the first predetermined ignition cut rotation speed when one of the first spark plug and the second spark plug is in a normal state and the other of the first spark plug and the second spark plug is in an abnormal state. In a first aspect, the fuel supply control unit stops the supply operation of the fuel to the internal combustion engine when the rotation speed of the internal combustion engine is equal to or higher than a first predetermined fuel cut implementation rotation speed when both the first spark plug and the second spark plug are in a normal state, and stops the supply operation of the fuel to the internal combustion engine when the rotation speed of the internal combustion engine is equal to or higher than a second predetermined fuel cut implementation rotation speed that is lower than the first predetermined fuel cut implementation rotation speed when one of the first spark plug and the second spark plug is in a normal state and the other of the first spark plug and the second spark plug is in an abnormal state.

[0008] In addition to the first aspect of the present invention, the present invention has a second aspect in which the second predetermined ignition cut execution speed is set to be higher than the second predetermined fuel cut execution speed. [Effects of the Invention]

[0009] According to the internal combustion engine control device of the first aspect of the present invention, the ignition control unit stops the ignition operation by the first spark plug and the second spark plug when the rotation speed of the internal combustion engine is equal to or higher than a first predetermined ignition cut rotation speed when both the first spark plug and the second spark plug are in a normal state, and stops the ignition operation by one of the first spark plug and the second spark plug when the rotation speed of the internal combustion engine is equal to or higher than a second predetermined ignition cut rotation speed that is lower than the first predetermined ignition cut rotation speed when one of the first spark plug and the second spark plug is in a normal state and the other of the first spark plug and the second spark plug is in an abnormal state, and By stopping the supply of fuel to the internal combustion engine when the engine speed is equal to or higher than a first predetermined fuel cut implementation speed, and stopping the supply of fuel to the internal combustion engine when the engine speed is equal to or higher than a second predetermined fuel cut implementation speed that is lower than the first predetermined fuel cut implementation speed when one of the first and second spark plugs is in a normal state and the other of the first and second spark plugs is in an abnormal state, it is possible to prevent the engine speed from increasing unnecessarily when an abnormality occurs in only one of the two spark plugs provided in the internal combustion engine, thereby maintaining the engine speed within an appropriate range and suppressing the occurrence of unstable combustion in the internal combustion engine.

[0010] In addition, according to the internal combustion engine control device of the second aspect of the present invention, the second predetermined ignition cut implementation speed is set to be higher than the second predetermined fuel cut implementation speed, so that if an abnormality occurs in only one of the two spark plugs provided in the internal combustion engine, a fuel cut can be performed first while an ignition cut can be performed in parallel, thereby preventing unburned fuel from being contained in the exhaust gas and preventing the internal combustion engine speed from increasing unnecessarily, thereby maintaining the internal combustion engine speed within an appropriate range and stabilizing combustion in the internal combustion engine. [Brief explanation of the drawings]

[0011] [Figure 1]FIG. 1 is a schematic diagram showing the configuration of an internal combustion engine control device (hereinafter sometimes referred to as an engine control device) according to an embodiment of the present invention, together with an internal combustion engine (hereinafter sometimes referred to as an engine). [Figure 2] Figure 2 is a time chart showing an example of the change in engine speed over time when the engine control device in this embodiment performs ignition cut control and fuel cut control, where Figure 2(a) shows a time chart when both the first spark plug and the second spark plug are normal, and Figure 2(b) shows a time chart when only one of the first spark plug and the second spark plug is abnormal. [Figure 3] FIG. 3 is a flowchart showing an example of an ignition cutoff execution engine speed and a fuel cutoff execution engine speed calculation process performed by the engine control device according to this embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, engine control devices according to embodiments of the present invention will be described in detail with reference to the drawings as appropriate.

[0013] <Engine configuration> First, with reference to FIG. 1, the configuration of an engine to which the engine control device of this embodiment is applied will be described in detail.

[0014] FIG. 1 is a schematic diagram showing the configuration of an engine control device according to this embodiment together with an engine.

[0015] As shown in FIG. 1, engine 1 is typically a four-stroke reciprocating internal combustion engine mounted on a vehicle such as a motorcycle (not shown). Its operating state is controlled by an engine control device 50 and includes a cylinder block 2. While engine 1 is shown in the figure as having a single cylinder 2a for ease of explanation, engine 1 may include multiple cylinders 2a, and the cylinders 2a may be arranged in an in-line, horizontally opposed, V-type, or other configuration. Engine 1 is typically water-cooled, and a water temperature sensor 101 is provided in a cooling water passage (not shown) in the side wall of cylinder block 2 to detect the temperature of the cooling water flowing through the cooling water passage. If engine 1 were air-cooled, a temperature sensor (not shown) capable of detecting the temperature of engine 1 would be provided in cylinder block 2 or elsewhere instead of water temperature sensor 101.

[0016] A piston 4 is disposed inside the cylinder block 2. The piston 4 is connected to a crankshaft 6 via a connecting rod 5. A reluctor 7 is provided on the crankshaft 6, which rotates coaxially with the crankshaft 6. A plurality of teeth 7a are provided on the outer circumferential surface of the reluctor 7, and are arranged side by side in a predetermined pattern in the circumferential direction. A crank angle sensor 102 is provided near the plurality of teeth 7a in a lower case (not shown) or the like attached to the bottom of the cylinder block 2 to detect the rotational angle of the crankshaft 6 so that the engine control device 50 can detect the rotational speed of the engine 1.

[0017] A cylinder head 8 is attached to the top of the cylinder block 2. The internal space defined by the inner wall surface of the cylinder block 2, the upper surface of the piston 4, and the inner wall surface of the cylinder head 8 cooperates to form a combustion chamber 9.

[0018] The cylinder block 2 and the cylinder head 8 are provided with two spark plugs 10a and 10b for each cylinder 2a, which ignite the air-fuel mixture generated in the combustion chamber 9 of that cylinder. The ignition operation of the spark plugs 10a and 10b is controlled by the engine control device 50, which controls the energization of the ignition coils L1 and L2, respectively. The spark plugs 10a and 10b are typically mass-produced, commercially available spark plugs with identical specifications. The figure illustrates an example in which one of the spark plugs is mounted in the cylinder block 2 and the other is mounted in the cylinder head 8. However, the mounting locations of the spark plugs 10a and 10b are not particularly limited as long as they can practically ignite the air-fuel mixture in the combustion chamber 9 equally. For example, both may be mounted in the cylinder block 2 or the cylinder head 8. The ignition timings of the spark plugs 10a and 10b may be set to be equal to each other or different from each other.

[0019] The cylinder head 8 is provided with an intake valve 12 that opens and closes communication between the combustion chamber 9 and an intake passage 11a. The intake passage 11a is formed in the cylinder head 8 and an intake pipe 11 attached to the cylinder head 8. The intake pipe 11 is provided with a fuel injection valve 13 that injects fuel into the intake passage 11a, and a throttle valve 14 that is located upstream of the fuel injection valve 13 and is a component of a throttle device (not shown). The intake pipe 11 is provided with an intake pressure sensor 103 between the intake valve 12 and the throttle valve 14 that detects the pressure (intake pressure) of the air flowing into the intake pipe 11. A throttle opening sensor 104 that detects the opening degree of the throttle valve 14 is attached to the main body of the throttle device. The fuel injection operation (valve opening operation) of the fuel injection valve 13 is controlled by controlling the supply of electricity to its solenoid valve (not shown). Note that the fuel injection valve 13 may be a type that injects fuel directly into the combustion chamber 9.

[0020] An exhaust pipe 15 is attached to the cylinder head 8 on the opposite side of the intake pipe 11, and an exhaust passage 15a that communicates with the combustion chamber 9 is formed within the cylinder head 8 and the exhaust pipe 15. The cylinder head 8 is also provided with an exhaust valve 16 that opens and closes the communication between the combustion chamber 9 and the exhaust passage 15a. A catalyst 109, which is typically a three-way catalyst, that purifies the exhaust gas discharged from the combustion chamber 9 is provided in the exhaust pipe 15 downstream of the exhaust valve 16, and an O2 sensor 110 that detects the oxygen concentration in the exhaust gas is provided upstream of and close to the catalyst 109.

[0021] The water temperature sensor 101 outputs an electrical signal, the voltage of which corresponds to the temperature of the cooling water flowing through the cooling water passage in the side wall of the cylinder block 2, to the engine control device 50. The crank angle sensor 102 outputs an electrical signal, the voltage of which varies depending on the number of teeth 7a of the reluctor 7, which rotates with the rotation of the crankshaft 6, and the recesses between them. The intake pressure sensor 103 outputs an electrical signal, the voltage of which corresponds to the pressure of the air flowing into the intake pipe 11 (intake pressure), to the engine control device 50. The throttle opening sensor 104 outputs an electrical signal, the voltage of which corresponds to the opening of the throttle valve 14 (throttle opening), to the engine control device 50. The O2 sensor 110 outputs an electrical signal, the voltage of which corresponds to the oxygen concentration in the exhaust gas upstream of the catalyst 109, to the engine control device 50. Reference numeral 120 denotes a vehicle speed sensor 120 that detects the vehicle speed from the rotation speed of the front wheels, which are the driven wheels of the vehicle, and the vehicle speed sensor 120 outputs an electrical signal exhibiting a voltage corresponding to the vehicle speed to the engine control device 50.

[0022] <Configuration of engine control unit> Next, with further reference to FIG. 2, the configuration of the engine control device 50 in this embodiment will be described in detail.

[0023] Figure 2 is a time chart showing an example of the change in engine speed over time when the engine control device in this embodiment performs ignition cut control and fuel cut control, where Figure 2(a) shows a time chart when both the first spark plug and the second spark plug are normal, and Figure 2(b) shows a time chart when only one of the first spark plug and the second spark plug is abnormal.

[0024] First, as shown in FIG. 1, the engine control device 50 is configured by an ECU (Electronic Control Unit) 150, which is an electronic control device mounted on a vehicle and controls the operation of the engine 1.

[0025] The ECU 150 is an arithmetic processing device including a microcomputer made up of a CPU (Central Processing Unit), memory, etc., and has memory and timers (not shown), in which necessary control and processing programs and control and processing data are stored. The ECU 150 also reads out necessary control and processing programs and control and processing data from the memory based on output signals from various sensors, such as a water temperature sensor 101, a crank angle sensor 102, an intake pressure sensor 103, a throttle opening sensor 104, an O2 sensor 110, and a vehicle speed sensor 120, and executes the control and processing programs to control the operation of various control targets, such as spark plugs 10a and 10b and fuel injection valve 13, thereby controlling the operating state of the engine 1.

[0026] Specifically, the ECU 150 includes an ignition control unit 151 that controls the ignition operation of the spark plugs 10a and 10b by controlling the supply of current to the ignition coils L1 and L2, a fuel injection control unit 152 that controls the fuel injection operation of the fuel injection valve 13 by controlling the supply of current to the fuel injection valve 13, and an abnormality determination unit 153 that determines whether or not there is an ignition abnormality in the spark plugs 10a and 10b. In the drawing, the ignition control unit 151, the fuel injection control unit 152, and the abnormality determination unit 153 are shown as functional blocks when a control / processing program is executed.

[0027] The ignition control unit 151 refers to data in a basic ignition timing map stored in memory to calculate, for each of the spark plugs 10a and 10b, a basic ignition timing that corresponds to the rotation speed of the engine 1 (engine speed) calculated based on the output signal from the crank angle sensor 102 and the throttle opening calculated based on the output signal from the throttle opening sensor 104, and also refers to data in a correction ignition timing map stored in memory to calculate, for each of the spark plugs 10a and 10b, a correction ignition timing that corresponds to the engine temperature calculated based on the output signal from the water temperature sensor 101. The ignition control unit 151 then outputs drive signals to the ignition coils L1 and L2, respectively, to energize them in accordance with the ignition timings calculated from the basic ignition timing and corrected ignition timing for each of the spark plugs 10a and 10b, thereby executing ignition control to ignite the spark plugs 10a and 10b.

[0028] The fuel injection control unit 152 refers to data on a basic fuel injection amount map stored in a memory to calculate a basic fuel injection amount corresponding to the engine speed calculated based on the output signal from the crank angle sensor 102 and the throttle opening calculated based on the output signal from the throttle opening sensor 104, and also refers to data on a correction fuel injection amount map stored in a memory to calculate a correction fuel injection amount corresponding to the engine temperature calculated based on the output signal from the water temperature sensor 101. The fuel injection control unit 152 then outputs a drive signal to the fuel injection valve 13 to energize and open it so that the fuel injection amount calculated from the basic fuel injection amount and the correction fuel injection amount is injected into the intake passage 11a at a predetermined fuel injection timing.

[0029] The abnormality determination unit 153 determines whether or not there is an abnormality in the ignition ability of the spark plug 10a (ignition abnormality) by detecting an abnormality in the electrical system from the ECU 150 through the ignition coil L1 to the spark plug 10a, and determines whether or not there is an abnormality in the ignition ability of the spark plug 10b (ignition abnormality) by detecting an abnormality in the electrical system from the ECU 150 through the ignition coil L2 to the spark plug 10b. For this purpose, from a practical point of view, it is preferable that the abnormality determination unit 153 detects whether or not there is an abnormality in the electrical system on the primary voltage side of each of the ignition coils L1 and L2, which has a lower voltage than the electrical system on the secondary voltage side. For example, the abnormality determination unit 153 detects the voltage or current of the electrical wiring W1 that electrically connects the output terminal of the drive circuit for the ignition plug 10a (not shown) of the ECU 150 and the input terminal of the primary coil (not shown) of the ignition coil L1, and if the detected voltage or current value falls within a predetermined range indicating an abnormality (typically a range below a value close to zero), it determines that an electrical abnormality such as a break or short circuit has occurred in the electrical system on the primary voltage side of the ignition coil L1, and determines that an abnormality has occurred in the ignition ability of the spark plug 10a. Similarly, the abnormality determination unit 153 detects the voltage or current of the electrical wiring W2 that electrically connects the output terminal of the drive circuit for the spark plug 10b (not shown) of the ECU 150 with the input terminal of the primary coil (not shown) of the ignition coil L2, and if the detected voltage or current value falls within a predetermined range indicating an abnormality (typically a range below a value close to zero), it determines that an electrical abnormality such as a break or short circuit has occurred in the electrical system on the primary voltage side of the ignition coil L2, and determines that an abnormality has occurred in the ignition capability of the spark plug 10b. Note that an abnormality in the ignition capability of the spark plug 10a does not only mean a state in which the spark plug 10a does not ignite at all even when the ECU 150 outputs a drive signal for energizing the spark plug 10a via the ignition coil L1, but also means an ignition state in which the spark plug 10a ignites to a certain extent but is not enough to ignite the air-fuel mixture. Similarly, an abnormality in the ignition ability of spark plug 10b does not only mean a state in which spark plug 10b does not ignite at all even when a drive signal for energizing spark plug 10b is output from ECU 150 via ignition coil L2, but also means an ignition state in which spark plug 10b ignites to a certain extent but is not enough to ignite the air-fuel mixture.

[0030] As shown in FIG. 2(a), when the abnormality determination unit 153 determines that the ignition capabilities of both spark plugs 10a and 10b are normal and not abnormal, the ignition control unit 151 inhibits the output of drive signals to the spark plugs 10a and 10b when the engine 1 speed exceeds a predetermined ignition cutoff engine speed NE2, thereby stopping the ignition operation of the spark plugs 10a and 10b. This is to prevent the engine 1 speed from excessively increasing, which would undesirably affect the internal mechanisms of the engine 1, or the exhaust gas temperature from becoming too high, which would undesirably affect the internal structure of the catalyst 109. In the figure, the engine speed intermittently exceeds the predetermined ignition cutoff engine speed NE2 between times t2 and t3, during which the ignition operation of the spark plugs 10a and 10b may not be performed. The value of the predetermined ignition cutoff engine speed NE2 is typically obtained by referring to the value of the ignition cutoff engine speed NE2 stored in memory.

[0031] Also, as shown in Figure 2(b), when the abnormality judgment unit 153 determines that an abnormality has occurred in the ignition capacity of only one of the spark plugs 10a and 10b, that is, when the abnormality judgment unit 153 determines that no abnormality has been found in the ignition capacity of the spark plug 10b and that it is normal, but determines that an abnormality has occurred in the ignition capacity of the spark plug 10a, or when the abnormality judgment unit 153 determines that no abnormality has been found in the ignition capacity of the spark plug 10a and that it is normal, but determines that an abnormality has occurred in the ignition capacity of the spark plug 10b, the ignition control unit 151 prohibits the output of a drive signal to the normal one of the spark plugs 10a and 10b when the engine speed of the engine 1 reaches or exceeds a predetermined ignition cut engine speed NE2', and stops the ignition operation that ignites the normal one of the spark plugs 10a and 10b. In the figure, the engine speed intermittently exceeds the predetermined ignition cutoff engine speed NE2' between times t2' and t3'. During this period, the ignition operation to ignite one of the normal spark plugs 10a and 10b may not be performed. The value of the predetermined ignition cutoff engine speed NE2' is typically obtained by referencing data on the value of the ignition cutoff engine speed NE2' stored in memory. The value of the ignition cutoff engine speed NE2' is set to a value smaller (a lower value) than the predetermined ignition cutoff engine speed NE2', so that if an abnormality occurs in the ignition capacity of only one of the spark plugs 10a and 10b, the ignition operation is stopped earlier than when the spark plugs are normal. Furthermore, depending on differences in ignition characteristics due to differences in the specifications and installation positions of the spark plugs 10a and 10b, the value of the predetermined ignition cutoff engine speed NE2' may be set individually depending on which of the spark plugs 10a and 10b has an abnormality.

[0032] 2A, when the abnormality determination unit 153 determines that no abnormality has occurred in the ignition capabilities of either the spark plugs 10a or 10b and that both are normal, the fuel injection control unit 152 prohibits the output of a drive signal to the fuel injection valve 13 and stops the fuel injection operation of the fuel injection valve 13 to inject fuel into the intake passage 11a when the engine 1 speed reaches or exceeds a predetermined fuel cut engine speed NE1, in order to avoid a situation in which the internal mechanisms of the engine 1 are unnecessarily affected by an excessive increase in the engine speed or an excessively high exhaust gas temperature unnecessarily affecting the internal structure of the catalyst 109. In the figure, the engine speed intermittently exceeds the predetermined fuel cut engine speed NE1 between times t1 and t4, and this period is a period in which the fuel injection operation of the fuel injection valve 13 to inject fuel into the intake passage 11a may not be performed. The value of the predetermined fuel cut engine speed NE1 is typically obtained by referring to data on the fuel cut engine speed NE1 stored in memory. In addition, from the viewpoint of prioritizing the stopping of the fuel injection operation that injects fuel from the fuel injection valve 13 into the intake passage 11a over the stopping of the ignition operation that ignites the spark plugs 10a and 10b, it is preferable to set the value of the predetermined fuel cut execution engine speed NE1 to a value smaller than the value of the predetermined ignition cut execution engine speed NE2.

[0033] Also, as shown in Figure 2(b), when the abnormality judgment unit 153 determines that an abnormality has occurred in the ignition capacity of only one of the spark plugs 10a and 10b, that is, when the abnormality judgment unit 153 determines that no abnormality has been found in the ignition capacity of the spark plug 10b and that it is normal, but determines that an abnormality has occurred in the ignition capacity of the spark plug 10a, or when the abnormality judgment unit 153 determines that no abnormality has been found in the ignition capacity of the spark plug 10a and that it is normal, but determines that an abnormality has occurred in the ignition capacity of the spark plug 10b, the fuel injection control unit 152 prohibits the output of a drive signal to the fuel injection valve 13 and stops the fuel injection operation that injects fuel from the fuel injection valve 13 into the intake passage 11a when the rotation speed of the engine 1 reaches or exceeds a predetermined fuel cut execution engine rotation speed NE1'. In the figure, the engine speed is intermittently equal to or higher than the predetermined fuel cut engine speed NE1' between times t1' and t4', and this period is a period during which a fuel injection operation for injecting fuel from the fuel injection valve 13 into the intake passage 11a may not be performed. The value of the predetermined fuel cut engine speed NE1' is typically obtained by referring to data on the value of the fuel cut engine speed NE1' stored in memory. The value of the predetermined fuel cut engine speed NE1' is set to a value smaller than the value of the predetermined fuel cut engine speed NE1, from the viewpoint of stopping the fuel injection operation earlier than when the ignition capability of only one of the spark plugs 10a and 10b is normal, if an abnormality occurs in the ignition capability of only one of the spark plugs. Furthermore, even if an abnormality occurs in the ignition capacity of only one of the spark plugs 10a and 10b, it is preferable to set the value of the predetermined fuel cut-off engine speed NE1' to a value smaller than the value of the predetermined ignition cut-off engine speed NE2', from the viewpoint of prioritizing the stopping of the fuel injection operation that injects fuel from the fuel injection valve 13 into the intake passage 11a over the stopping of the ignition operation that ignites the normal one of the spark plugs 10a and 10b, just as in the case where the abnormality judgment unit 153 determines that no abnormality has occurred in the ignition capacity of both the spark plugs 10a and 10b and that both are normal.Furthermore, when an abnormality occurs in the ignition capacity of only one of the spark plugs 10a and 10b, not only the fuel injection operation but also the ignition operation should be stopped earlier than when neither the ignition capacity of the spark plugs 10a and 10b is abnormal and both are normal. Therefore, it is preferable that the difference between the predetermined ignition cut engine speed NE2' and the predetermined fuel cut engine speed NE1' when an abnormality occurs in the ignition capacity of only one of the spark plugs 10a and 10b is set to be smaller than the difference between the predetermined ignition cut engine speed NE2 and the predetermined fuel cut engine speed NE1 when neither the ignition capacity of the spark plugs 10a and 10b is abnormal and both are normal. Furthermore, depending on differences in ignition characteristics due to differences in the specifications and installation positions of the spark plugs 10a and 10b, the predetermined fuel cut engine speed NE1' may be set to different values ​​depending on which of the spark plugs 10a and 10b has an abnormality.

[0034] The engine control device 50 having the configuration described above executes an ignition cutoff engine speed and a fuel cutoff engine speed calculation process including an abnormality determination process described below, and calculates an ignition cutoff engine speed and a fuel cutoff engine speed for stopping the ignition operation of a normal spark plug and stopping the fuel injection operation when it determines that an abnormality has occurred in the ignition capacity of only one of the spark plugs 10a and 10b. Below, the operation of the engine control device 50 when executing the ignition cutoff engine speed and fuel cutoff engine speed calculation process will be described with further reference to Figure 3.

[0035] <Processing for calculating engine speed for ignition cut and engine speed for fuel cut> FIG. 3 is a flowchart showing an example of an ignition cutoff execution engine speed and a fuel cutoff execution engine speed calculation process performed by the engine control device according to this embodiment.

[0036] 3 starts when an ignition switch (not shown) is turned on from an off state and ECU 150 is started, and the process of calculating the ignition cutoff engine speed and the fuel cutoff engine speed proceeds to step S1. While ECU 150 is in the started state, the process of calculating the ignition cutoff engine speed and the fuel cutoff engine speed is repeatedly executed at predetermined control intervals by reading the necessary control and processing programs and control and processing data from memory. For convenience, the following description will be given assuming that spark plug 10a is the first spark plug and spark plug 10b is the second spark plug, but the same applies if spark plug 10b is the first spark plug and spark plug 10a is the second spark plug.

[0037] In the process of step S1, the abnormality determination unit 153 determines whether an ignition abnormality has occurred in the spark plug 10a. Specifically, the abnormality determination unit 153 detects the voltage applied to the electrical wiring W1 or the current flowing through the electrical wiring W1. If the detected voltage or current falls within a predetermined range indicating an abnormality, the abnormality determination unit 153 determines that an electrical abnormality, such as a disconnection or short circuit, has occurred in the electrical system on the primary voltage side of the ignition coil L1, and determines that an abnormality has occurred in the ignition capability of the spark plug 10a. If the determination results in an ignition abnormality in the spark plug 10a, the abnormality determination unit 153 advances the ignition cutoff engine speed and fuel cutoff engine speed calculation process to the process of step S2. On the other hand, if the determination results in no ignition abnormality in the spark plug 10a, the abnormality determination unit 153 advances the ignition cutoff engine speed and fuel cutoff engine speed calculation process to the process of step S3. Note that the data within the predetermined range indicating such an abnormality is referenced from data stored in memory.

[0038] In the process of step S2, the abnormality determination unit 153 determines whether an ignition abnormality has occurred in the spark plug 10b. Specifically, the abnormality determination unit 153 detects the voltage applied to the electrical wiring W2 or the current flowing through the electrical wiring W2. If the detected voltage or current falls within a predetermined range indicating an abnormality, the abnormality determination unit 153 determines that an electrical abnormality, such as a wire break or short circuit, has occurred in the electrical system on the primary voltage side of the ignition coil L2, and determines that an abnormality has occurred in the ignition capability of the spark plug 10b. If the determination results in an ignition abnormality in the spark plug 10b, the abnormality determination unit 153 advances the ignition cutoff engine speed and fuel cutoff engine speed calculation process to step S4. On the other hand, if the determination results in no abnormality in the spark plug 10b, the abnormality determination unit 153 advances the ignition cutoff engine speed and fuel cutoff engine speed calculation process to step S5. Note that the data within the predetermined range indicating an abnormality is stored in memory.

[0039] In the process of step S3, the abnormality determination unit 153 determines whether an ignition abnormality has occurred in the spark plug 10b. Specifically, the abnormality determination unit 153 detects the voltage applied to the electrical wiring W2 or the current flowing through the electrical wiring W2. If the detected voltage or current falls within a predetermined range indicating an abnormality, the abnormality determination unit 153 determines that an electrical abnormality, such as a disconnection or short circuit, has occurred in the electrical system on the primary voltage side of the ignition coil L2, and determines that an abnormality has occurred in the ignition capability of the spark plug 10b. If the determination results in an ignition abnormality in the spark plug 10b, the abnormality determination unit 153 advances the ignition cutoff engine speed and fuel cutoff engine speed calculation process to step S6. On the other hand, if the determination results in no abnormality in the spark plug 10b, the abnormality determination unit 153 advances the ignition cutoff engine speed and fuel cutoff engine speed calculation process to step S7. Note that the data within the predetermined range indicating an abnormality is stored in memory.

[0040] In the processing of step S4, since abnormalities have occurred in both spark plugs 10a and 10b, ignition control unit 151 stops the supply of current to both spark plugs 10a and 10b by the drive signals to forcibly stop their ignition operations, and fuel injection control unit 152 stops the supply of current to fuel injection valve 13 by the drive signal to forcibly stop its fuel injection operation, thereby forcibly stopping the operation of engine 1. This completes the processing of step S4, and the current series of processes for calculating the ignition cutoff engine speed and fuel cutoff engine speed ends.

[0041] In the processing of step S5, since an ignition abnormality has occurred only in the spark plug 10a, the ignition control unit 151 refers to the data of the value of the ignition cut-off engine speed NE2' stored in memory and sets that value to the value of the predetermined ignition cut-off engine speed NE2', and the fuel injection control unit 152 refers to the data of the fuel cut-off engine speed NE1' stored in memory and sets that value to the value of the predetermined fuel cut-off engine speed NE1'. Since the value of the predetermined ignition cutoff engine speed NE2' is smaller than the value of the predetermined ignition cutoff engine speed NE2 when there is no abnormality in the ignition capabilities of both spark plugs 10a and 10b and both are normal, the value of the predetermined ignition cutoff engine speed NE2' is calculated as a value reduced from the value of the predetermined ignition cutoff engine speed NE2, and since the value of the predetermined fuel cutoff engine speed NE1' is smaller than the value of the predetermined fuel cutoff engine speed NE1 when there is no abnormality in the ignition capabilities of both spark plugs 10a and 10b and both are normal, the value of the predetermined fuel cutoff engine speed NE1' is calculated as a value reduced from the value of the predetermined fuel cutoff engine speed NE1. Ignition control unit 151 then changes the value of the predetermined ignition cutoff engine speed NE2 to the value of a predetermined ignition cutoff engine speed NE2', and stops the ignition operation of spark plug 10b when the value of the engine speed calculated based on the output signal from crank angle sensor 102 becomes equal to or greater than the predetermined ignition cutoff engine speed NE2'. Furthermore, fuel injection control unit 152 changes the value of the predetermined fuel cutoff engine speed NE1 to the value of a predetermined fuel cutoff engine speed NE1', and stops the fuel injection operation of fuel injection valve 13 when the value of the engine speed calculated based on the output signal from crank angle sensor 102 becomes equal to or greater than the predetermined ignition cutoff engine speed NE1'.

[0042] In the processing of step S6, since an ignition abnormality has occurred only in spark plug 10b, similar to the processing of step S6, the ignition control unit 151 refers to the data of the value of the ignition cut-off engine speed NE2' stored in memory and sets that value to the value of the predetermined ignition cut-off engine speed NE2', and the fuel injection control unit 152 refers to the data of the value of the fuel cut-off engine speed NE1' stored in memory and sets that value to the value of the predetermined fuel cut-off engine speed NE1'. Since the value of the predetermined ignition cutoff engine speed NE2' is smaller than the value of the predetermined ignition cutoff engine speed NE2 when there is no abnormality in the ignition capabilities of both spark plugs 10a and 10b and both are normal, the value of the predetermined ignition cutoff engine speed NE2' is calculated as a value reduced from the value of the predetermined ignition cutoff engine speed NE2, and since the value of the predetermined fuel cutoff engine speed NE1' is smaller than the value of the predetermined fuel cutoff engine speed NE1 when there is no abnormality in the ignition capabilities of both spark plugs 10a and 10b and both are normal, the value of the predetermined fuel cutoff engine speed NE1' is calculated as a value reduced from the value of the predetermined fuel cutoff engine speed NE1. Ignition control unit 151 then changes the value of the predetermined ignition cutoff engine speed NE2 to the value of a predetermined ignition cutoff engine speed NE2', and stops the ignition operation of spark plug 10a when the value of the engine speed calculated based on the output signal from crank angle sensor 102 becomes equal to or greater than the predetermined ignition cutoff engine speed NE2'. Furthermore, fuel injection control unit 152 changes the value of the predetermined fuel cutoff engine speed NE1 to the value of a predetermined fuel cutoff engine speed NE1', and stops the fuel injection operation of fuel injection valve 13 when the value of the engine speed calculated based on the output signal from crank angle sensor 102 becomes equal to or greater than the predetermined ignition cutoff engine speed NE1'.

[0043] In the processing of step S7, since neither the ignition plug 10a nor the 10b has an abnormality, the ignition control unit 151 references the data for the value of the ignition cut execution engine speed NE2 stored in memory and sets that value to the value of the predetermined ignition cut execution engine speed NE2, and the fuel injection control unit 152 references the data for the value of the ignition cut execution engine speed NE1 stored in memory and sets that value to the value of the predetermined fuel cut execution engine speed NE1. Note that in the processing of step S7, the ignition control unit 151 does not set the value of the predetermined ignition cut execution engine speed NE2' in place of the value of the predetermined ignition cut execution engine speed NE2, and the fuel injection control unit 152 does not set the value of the predetermined fuel cut execution engine speed NE1' in place of the value of the predetermined fuel cut execution engine speed NE1.

[0044] In the internal combustion engine control device 50 of the present embodiment described above, when the first spark plugs 10a, 10b and the second spark plugs 10b, 10a are both in a normal state, the ignition control unit 151 stops the ignition operation by the first spark plugs 10a, 10b and the second spark plugs 10b, 10a when the rotation speed of the internal combustion engine 1 is equal to or higher than a first predetermined ignition cut rotation speed NE2, and When one of the first spark plugs 10a, 10b and the second spark plugs 10b, 10a is in a normal state and the other of the first spark plugs 10a, 10b and the second spark plugs 10b, 10a is in an abnormal state, when the rotation speed of the internal combustion engine 1 is equal to or higher than a second predetermined ignition cut rotation speed NE2' which is lower than the first predetermined ignition cut rotation speed NE2, the ignition operation by one of the first spark plugs 10a, 10b and the second spark plugs 10b, 10a is stopped, and the fuel supply control unit 152 controls the first spark plugs 10a, 10b and the second spark plugs 10b, 10a to be stopped. When both spark plugs 10b, 10a are in a normal state, the supply of fuel to the internal combustion engine 1 is stopped when the rotation speed of the internal combustion engine 1 is equal to or higher than a first predetermined fuel cut execution rotation speed NE1. When one of the first spark plugs 10a, 10b and the second spark plugs 10b, 10a is in a normal state and the other of the first spark plugs 10a, 10b and the second spark plugs 10b, 10a is in an abnormal state, the supply of fuel to the internal combustion engine 1 is stopped when the rotation speed of the internal combustion engine 1 is equal to or higher than a second predetermined fuel cut execution rotation speed NE1' which is lower than the first predetermined fuel cut execution rotation speed NE1. This prevents the rotation speed of the internal combustion engine 1 from increasing unnecessarily when an abnormality occurs in only one of the two spark plugs 10a, 10b provided in the internal combustion engine 1, thereby maintaining the rotation speed of the internal combustion engine 1 within an appropriate range and suppressing the occurrence of unstable combustion in the internal combustion engine 1.

[0045] In addition, in the internal combustion engine control device 50 of this embodiment, the second predetermined ignition cut implementation speed NE2' is set to be higher than the second predetermined fuel cut implementation speed NE1', so that if an abnormality occurs in only one of the two ignition plugs 10a, 10b provided in the internal combustion engine 1, a fuel cut can be performed first while an ignition cut is performed in parallel.This prevents unburned fuel from being contained in the exhaust gas, prevents the rotational speed of the internal combustion engine 1 from increasing unnecessarily, maintains the rotational speed of the internal combustion engine 1 within an appropriate range, and stabilizes combustion in the internal combustion engine 1.

[0046] The present invention is not limited to the above-described embodiments in terms of the type, shape, arrangement, number, etc. of the components, and it goes without saying that the components can be appropriately modified within the scope of the gist of the invention, such as by appropriately replacing them with components that have equivalent effects. [Industrial Applicability]

[0047] As described above, the present invention provides an internal combustion engine control device that can prevent the engine speed from increasing unnecessarily when an abnormality occurs in only one of the two spark plugs provided in the internal combustion engine, maintain the engine speed within an appropriate range, and prevent unstable combustion from occurring in the internal combustion engine.Due to its versatile and universal nature, it is expected to be widely applicable to internal combustion engine control devices for motorcycles. [Explanation of symbols]

[0048] 1...Engine (internal combustion engine) 2...Cylinder block 2a...cylinder 4...Piston 5...Connecting rod 6...Crankshaft 7...Relacta 7a…teeth part 8...Cylinder head 9...Combustion chamber 10a, 10b…Spark plug 11...Intake pipe 11a...intake passage 12...Intake valve 13...Fuel injection valve 14...Throttle valve 15...Exhaust pipe 15a...Exhaust passage 16...Exhaust valve 50...Engine control device (internal combustion engine control device) 100...Engine control device 101...Water temperature sensor 102...Crank angle sensor 103...Intake pressure sensor 104...Throttle opening sensor 109...Catalyst 110...O2 sensor 120...Vehicle speed sensor 150…ECU 151...Ignition control unit 152...Fuel injection control unit (fuel supply control unit) 153...Abnormality determination section L1, L2... Ignition coil W1, W2...electrical wiring

Claims

1. An internal combustion engine control device comprising: an ignition control unit that controls an ignition operation by a first spark plug and a second spark plug provided for one cylinder of an internal combustion engine; and a fuel supply control unit that controls a supply operation of fuel to the internal combustion engine, the ignition control unit stops the ignition operation by the first spark plug and the second spark plug when the rotation speed of the internal combustion engine is equal to or higher than a first predetermined ignition cut rotation speed when both the first spark plug and the second spark plug are in a normal state, and stops the ignition operation by one of the first spark plug and the second spark plug when the rotation speed of the internal combustion engine is equal to or higher than a second predetermined ignition cut rotation speed that is lower than the first predetermined ignition cut rotation speed when one of the first spark plug and the second spark plug is in a normal state and the other of the first spark plug and the second spark plug is in an abnormal state, The fuel supply control unit stops the supply of fuel to the internal combustion engine when the rotational speed of the internal combustion engine is equal to or higher than a first predetermined fuel cut implementation rotational speed when both the first spark plug and the second spark plug are in a normal state, and stops the supply of fuel to the internal combustion engine when the rotational speed of the internal combustion engine is equal to or higher than a second predetermined fuel cut implementation rotational speed that is lower than the first predetermined fuel cut implementation rotational speed when one of the first spark plug and the second spark plug is in a normal state and the other of the first spark plug and the second spark plug is in an abnormal state.

2. 2. The internal combustion engine control device according to claim 1, wherein the second predetermined ignition cutoff execution rotational speed is set to be higher than the second predetermined fuel cutoff execution rotational speed.

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