Internal combustion engine control device

Abstract

To provide an internal combustion engine control device capable of securing various characteristics such as good exhaust gas characteristics while suppressing deterioration of output of an internal combustion engine when an abnormality has occurred only in either of two ignition plugs provided in the internal combustion engine.SOLUTION: In an internal combustion engine control device 50, compared to supply amount of fuel to be supplied to an internal combustion engine 1 when both of a first ignition plug 10a, 10b and a second ignition plug 10b, 10a are in the normal state, a fuel supply control section 152 performs setting so as to decrease the supply amount of the fuel as a load increases on a high load side of the load of the internal combustion engine 1 and increase the supply amount of the fuel as the load decreases on a low load side of the load of the internal combustion engine 1 when one of the first ignition plug 10a, 10b and the second ignition plug 10b, 10a is in the normal state and the other of the first ignition plug 10a, 10b and the second ignition plug 10b, 10a is in the abnormal state.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, Patent Document 1 discloses a configuration for diagnosing an abnormality in the ignition system based on the combustion state of the internal combustion engine and adjusting the ignition timing in accordance with the diagnosis results, but does not disclose or suggest any configuration for adjusting the amount of fuel supplied to the internal combustion engine. In particular, since an abnormal spark plug cannot demonstrate its normal ignition ability, if only the ignition timing is adjusted without adjusting the amount of fuel supplied, the amount of unburned fuel that should have been burned will increase, which not only reduces the output of the internal combustion engine but also tends to deteriorate various characteristics such as exhaust gas characteristics due to the increase in unburned fuel, leaving room for improvement.

[0006] The present invention was made after considering the above-mentioned considerations, and aims to provide an internal combustion engine control device that can suppress a decrease in the output of the internal combustion engine while ensuring good exhaust gas characteristics and other characteristics when an abnormality occurs in only one of the two spark plugs provided in the internal combustion engine. [Means for solving the problem]

[0007] In order to achieve the above-mentioned object, the present invention provides, in a first aspect, an internal combustion engine control device comprising an ignition control unit that controls the ignition operation by a first spark plug and a second spark plug provided for one cylinder of the internal combustion engine, and a fuel supply control unit that controls the fuel supply operation to the internal combustion engine, wherein, compared to the amount of fuel supplied to the internal combustion engine when both the first spark plug and the second spark plug are in a normal state, 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 is set to decrease the amount of fuel supplied to the internal combustion engine as the load increases on the high load side of the internal combustion engine, and to increase the amount of fuel supplied to the internal combustion engine as the load decreases on the low load side of the internal combustion engine.

[0008] In addition to the first aspect of the present invention, a second aspect of the present invention is that, when one of the first spark plug and the second spark plug is in the normal state and the other of the first spark plug and the second spark plug is in the abnormal state, the fuel supply control unit sets the amount of fuel supplied when both the first spark plug and the second spark plug are in the normal state in accordance with the rotation speed of the internal combustion engine, so as to decrease the amount of fuel supplied as the throttle opening becomes larger on the side where the throttle opening is large, and to increase the amount of fuel supplied as the throttle opening becomes smaller on the side where the throttle opening is small. [Effects of the Invention]

[0009] According to the internal combustion engine control device of the first aspect of the present invention, 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 sets the amount of fuel supplied to the internal combustion engine to decrease as the load increases on the high load side of the internal combustion engine and to increase as the load decreases on the low load side of the internal combustion engine, compared to the amount of fuel supplied when both the first spark plug and the second spark plug are in a normal state.This makes it possible to suppress a decrease in the output of the internal combustion engine while ensuring various characteristics such as good exhaust gas characteristics when an abnormality occurs in only one of the two spark plugs provided in the internal combustion engine.

[0010] In addition, according to the internal combustion engine control device of the second aspect of the present invention, 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 reduces the amount of fuel supplied when both the first spark plug and the second spark plug are in a normal state in accordance with the rotation speed of the internal combustion engine, and on the side where the throttle opening of the internal combustion engine is large, as the throttle opening increases, and increases the amount of fuel supplied on the side where the throttle opening is small, as the throttle opening decreases.This makes it possible to more reliably suppress a decrease in the output of the internal combustion engine while more reliably achieving various characteristics such as good exhaust gas characteristics when an abnormality occurs in only one of the two spark plugs provided 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 shows an example of a fuel injection amount correction coefficient map used by the engine control device in this embodiment, where Figure 2(a) shows an example of a correction coefficient map that is applied when only the first spark plug is abnormal and has a fuel injection amount correction coefficient value defined according to the engine speed value and the throttle opening value, and Figure 2(b) shows an example of a correction coefficient map that is applied when only the second spark plug is abnormal and has a fuel injection amount correction coefficient value defined according to the engine speed value and the throttle opening value. [Figure 3] FIG. 3 is a flowchart showing an example of a correction coefficient calculation process of 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 in cooperation with each other forms 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 shows an example of a fuel injection amount correction coefficient map used by the engine control device in this embodiment, where Figure 2(a) shows an example of a correction coefficient map that is applied when the second spark plug is normal and only the first spark plug is abnormal, and has a fuel injection amount correction coefficient value defined according to the engine speed value and the throttle opening value, and Figure 2(b) shows an example of a correction coefficient map that is applied when the first spark plug is normal and only the second spark plug is abnormal, and has a fuel injection amount correction coefficient value defined according to the engine speed value and the throttle opening value.

[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 calculates 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, with reference to data on a basic fuel injection amount map stored in memory. The fuel injection control unit 152 also calculates a corrected fuel injection amount corresponding to the engine temperature calculated based on the output signal from the water temperature sensor 101, with reference to data on a corrected fuel injection amount map stored in memory. 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 corrected fuel injection amount is injected into the intake passage 11a at a predetermined fuel injection timing. The fuel injection amount calculated from the basic fuel injection amount and the corrected fuel injection amount is used as the normal fuel injection amount when the ignition capabilities of both the spark plugs 10a and 10b are normal.

[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] Here, 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 sets the fuel injection amount to be injected into the intake passage 11a so that it gradually decreases as the load of the engine 1 increases on the high load side and gradually increases as the load of the engine 1 decreases on the low load side, compared to the fuel injection amount to be injected into the intake passage 11a when it is determined that both the spark plugs 10a and 10b are normal. In this way, as the load of engine 1 increases on the high load side, the fuel injection amount becomes excessive relative to the ignition capacity in the event of an abnormality. Taking this into consideration, on the high load side, the fuel injection amount is gradually reduced as the load of engine 1 increases, and on the low load side, the fuel injection amount is gradually increased or decreased as the load of engine 1 decreases, taking into consideration that as the load of engine 1 decreases on the low load side, the fuel injection amount becomes insufficient relative to the ignition capacity in the event of an abnormality. By doing so, even when an abnormality occurs in the ignition capacity of only one of spark plugs 10a and 10b, it is possible to adjust and optimize the fuel injection amount. The load on engine 1 may be determined based on the calculated output of engine 1, but in practice it is preferable to determine the load based on the throttle opening calculated based on the output signal from throttle opening sensor 104. For example, if an intermediate throttle opening between fully closed and fully open is assumed to be 50% of the fully open throttle, the throttle opening region exceeding 50% of the fully open throttle is the high load region, and the throttle opening region below 50% of the fully open throttle is the low load region. In addition, at such intermediate throttle openings, fuel injection control unit 152 does not need to adjust the fuel injection amount.Furthermore, if necessary, such intermediate opening may be defined as being offset from 50% of the fully open opening to either a higher or lower opening, or may be defined to have a predetermined opening range, such as an opening range of 40% to 60% of the fully open opening, and the high load side region and the low load side region will also be defined accordingly.

[0031] Furthermore, in order to reliably adjust the excess or deficiency of the fuel injection amount when the abnormality determination unit 153 determines that an abnormality has occurred in the ignition capacity of only one of the spark plugs 10a and 10b, the fuel injection control unit 152 preferably uses a correction coefficient map such as that shown in FIG. 2. The correction coefficient maps shown in FIGS. 2(a) and 2(b) are applied depending on the spark plug in which the abnormality has occurred when an abnormality has occurred in the ignition capacity of only one of the spark plugs 10a and 10b, and are stored in advance as data in a memory. The correction coefficient maps shown in FIGS. 2(a) and 2(b) may have the same content. However, if the spark plugs 10a and 10b have different ignition characteristics, such as specifications and ignition timing, different correction coefficients can be specified. This allows for a high degree of flexibility in adjusting and optimizing the fuel injection amount when an abnormality has occurred in the ignition capacity of only one of the spark plugs 10a and 10b.

[0032] First, as an example, when an abnormality occurs in the ignition capability of only spark plug 10a as the first spark plug, the correction coefficient map shown in Fig. 2(a) is used. The correction coefficient map shown in Fig. 2(a) is a map having values ​​of correction coefficients MAL111 to MAL1nm defined according to engine speeds NE1 to NEm (m is a natural number greater than 1) and throttle openings TH1 to THn (n is a natural number greater than 1), and the data is stored in memory. Here, if the throttle opening corresponding to an intermediate load of engine 1 is THa (a is a natural number greater than 1 and less than n), the values ​​of correction coefficients MAL1a1 to MAL1am corresponding to each of engine speeds NE1 to NEm become the correction coefficient values ​​at the time of intermediate load. Here, the low load side of the engine 1 is the side of the throttle opening TH smaller than the throttle opening THa (the side smaller than THa and equal to or larger than TH1), so if the engine speed NE is represented by NEb (b is a natural number greater than 1 and smaller than m), the correction coefficient will exhibit correction coefficient values ​​MAL1ab to MAL11b that gradually increase as the throttle opening decreases from THa to TH1, and this trend is similar for each of the engine speeds NE1 to NEm. On the other hand, the high load side of the engine 1 is the side of the throttle opening TH larger than the throttle opening THa (the side larger than THa and equal to or smaller than THn), so if the engine speed NE is represented by NEb, the correction coefficient will exhibit correction coefficient values ​​MAL1ab to MAL1nb that gradually decrease as the throttle opening increases from THa to THn, and this trend is similar for each of the engine speeds NE1 to NEm. In the correction coefficient map shown in FIG. 2(a), the values ​​of the correction coefficients MAL1a1 to MAL1am at the throttle opening THa corresponding to the medium load are typically set to 1, the values ​​of the correction coefficients MAL111 to MAL11m on the low load side are typically greater than 1, and the values ​​of the correction coefficients MAL1n1 to MAL1nm on the high load side are typically positive values ​​less than 1.Furthermore, on the side of the throttle opening TH smaller than the throttle opening THa and on the side of the throttle opening TH larger than the throttle opening THa, the value of the correction coefficient corresponding to each throttle opening TH1, etc. typically increases as the engine speed NE increases from NE1 to NEm.

[0033] When the abnormality determination unit 153 determines that an abnormality has occurred in the ignition capability of only the spark plug 10a, the fuel injection control unit 152 refers to the data of the correction coefficient map stored in the memory as shown in Figure 2(a) and calculates a correction coefficient according 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.By multiplying this correction coefficient by the fuel injection amount (the fuel injection amount calculated from the basic fuel injection amount and the corrected fuel injection amount) in normal times when the ignition capabilities of both the spark plugs 10a and 10b are normal, the fuel injection control unit 152 sets the fuel injection amount to be injected into the intake passage 11a so that it gradually decreases as the load of the engine 1 increases on the high load side and gradually increases as the load of the engine 1 decreases on the low load side, compared to the fuel injection amount to be injected into the intake passage 11a when it is determined that both the spark plugs 10a and 10b are normal.

[0034] As an example, when an abnormality occurs in the ignition ability of only spark plug 10b as the second spark plug, the correction coefficient map shown in Figure 2(b) is used. The correction coefficient map shown in Figure 2(b) is similar to the correction coefficient map shown in Figure 2(a), but it is a map having values ​​of correction coefficients MAL211 to MAL2nm defined according to engine speeds NE1 to NEm and throttle openings TH1 to THn, and the data is stored in memory. Here, if the throttle opening corresponding to an intermediate load of engine 1 is THa, the values ​​of correction coefficients MAL2a1 to MAL2am corresponding to each of engine speeds NE1 to NEm become the correction coefficient values ​​at the time of intermediate load. Here, the low load side of the engine 1 is the side of the throttle opening TH smaller than the throttle opening THa (the side smaller than THa and equal to or greater than TH1), so if the engine speed NE is described as NEb, the correction coefficient will exhibit correction coefficient values ​​MAL2ab to MAL21b that gradually increase as the throttle opening decreases from THa to TH1, and this trend is similar for each of the engine speeds NE1 to NEm. On the other hand, the high load side of the engine 1 is the side of the throttle opening TH larger than the throttle opening THa (the side larger than THa and equal to or less than THn), so if the engine speed NE is described as NEb, the correction coefficient will exhibit correction coefficient values ​​MAL2ab to MAL2nb that gradually decrease as the throttle opening increases from THa to THn, and this trend is similar for each of the engine speeds NE1 to NEm. 2(b), the values ​​of the correction coefficients MAL2a1 to MAL2am at the throttle opening THa corresponding to an intermediate load are typically set to 1, the values ​​of the correction coefficients MAL211 to MAL21m, etc. on the low load side are typically greater than 1, and the values ​​of the correction coefficients MAL2n1 to MAL2nm, etc. on the high load side are typically positive values ​​less than 1. Furthermore, on the throttle opening TH side smaller than THa and on the throttle opening TH side larger than THa, the value of the correction coefficient corresponding to each throttle opening TH1, etc. typically increases as the engine speed NE increases from NE1 to NEm.

[0035] When the abnormality determination unit 153 determines that an abnormality has occurred in the ignition capability of only the spark plug 10b, the fuel injection control unit 152 refers to the data of the correction coefficient map stored in the memory as shown in Figure 2(b) and calculates a correction coefficient according 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. By multiplying this correction coefficient by the fuel injection amount (the fuel injection amount calculated from the basic fuel injection amount and the corrected fuel injection amount) in normal times when the ignition capabilities of both the spark plugs 10a and 10b are normal, the fuel injection control unit 152 sets the fuel injection amount to be injected into the intake passage 11a so that it gradually decreases as the load of the engine 1 increases on the high load side and gradually increases as the load of the engine 1 decreases on the low load side, compared to the fuel injection amount to be injected into the intake passage 11a when it is determined that both the spark plugs 10a and 10b are normal.

[0036] The engine control device 50 having the configuration described above executes a correction coefficient calculation process including an abnormality determination process described below, so that when it determines that an abnormality has occurred in the ignition ability of only one of the spark plugs 10a and 10b, it refers to correction coefficient map data stored in a memory as shown in Figures 2(a) and 2(b) and calculates a correction coefficient 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. Hereinafter, the operation of the engine control device 50 when executing the correction coefficient calculation process will be described with further reference to Figure 3.

[0037] <Correction coefficient calculation process> FIG. 3 is a flowchart showing an example of a correction coefficient calculation process of the engine control device according to this embodiment.

[0038] 3 starts when an ignition switch (not shown) is turned on from an off state and the ECU 150 is started, and the correction coefficient calculation process proceeds to step S1. While the ECU 150 is in the started state, the correction coefficient calculation process is repeatedly executed at predetermined control intervals by reading out the necessary control and processing programs and control and processing data from the memory. For convenience, the following description will be given assuming that the spark plug 10a is the first spark plug and the spark plug 10b is the second spark plug, but the same applies if the spark plug 10b is the first spark plug and the spark plug 10a is the second spark plug.

[0039] 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 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 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 correction coefficient 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 correction coefficient 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.

[0040] 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, and if the detected voltage or current falls within a predetermined range indicating an abnormality, 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. If the determination results in an ignition abnormality in the spark plug 10b, the abnormality determination unit 153 advances the correction coefficient calculation process to the process of 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 correction coefficient calculation process to the process of step S5. Note that the data within the predetermined range indicating such an abnormality is referenced from data stored in memory.

[0041] 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, and if the detected voltage or current falls within a predetermined range indicating an abnormality, 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. If the determination results in an ignition abnormality in the spark plug 10b, the abnormality determination unit 153 advances the correction coefficient calculation process to the process of 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 correction coefficient calculation process to the process of step S7. Note that the data within the predetermined range indicating such an abnormality is referenced from data stored in memory.

[0042] In the processing of step S4, since abnormalities have occurred in both the spark plugs 10a and 10b, the ignition control unit 151 stops the supply of current to both the spark plugs 10a and 10b by the drive signals to forcibly stop their ignition operations, and the fuel injection control unit 152 stops the supply of current to the fuel injection valve 13 by the drive signal to forcibly stop its fuel injection operation, thereby forcibly stopping the operation of the engine 1. This completes the processing of step S4, and the current series of correction coefficient calculation processing ends.

[0043] In the processing of step S5, since an ignition abnormality has occurred only in spark plug 10a, fuel injection control unit 152 calculates a correction coefficient for the case where an ignition abnormality has occurred only in spark plug 10a. Specifically, fuel injection control unit 152 refers to data of a correction coefficient map stored in a memory as shown in Fig. 2(a) and calculates a correction coefficient value corresponding to the engine speed calculated based on the output signal from crank angle sensor 102 and the throttle opening calculated based on the output signal from throttle opening sensor 104. This completes the processing of step S5, and ends the current series of correction coefficient calculation processing. Furthermore, the fuel injection control unit 152 multiplies the correction coefficient of the value calculated in this manner by the normal fuel injection amount (fuel injection amount calculated from the basic fuel injection amount and the corrected fuel injection amount) when the ignition capabilities of both spark plugs 10a and 10b are normal, and thereby sets the fuel injection amount to be injected into the intake passage 11a so that it gradually decreases as the load on the engine 1 increases on the high load side and gradually increases as the load on the engine 1 decreases on the low load side, compared to the fuel injection amount to be injected into the intake passage 11a when it is determined that both spark plugs 10a and 10b are normal.

[0044] In the processing of step S6, since an ignition abnormality has occurred only in spark plug 10b, fuel injection control unit 152 calculates a correction coefficient for the case where an ignition abnormality has occurred only in spark plug 10b. Specifically, fuel injection control unit 152 refers to data of a correction coefficient map stored in memory as shown in Fig. 2(b) and calculates a correction coefficient value corresponding to the engine speed calculated based on the output signal from crank angle sensor 102 and the throttle opening calculated based on the output signal from throttle opening sensor 104. This completes the processing of step S5, and ends the current series of correction coefficient calculation processing. Furthermore, the fuel injection control unit 152 multiplies the correction coefficient of the value calculated in this manner by the normal fuel injection amount (fuel injection amount calculated from the basic fuel injection amount and the corrected fuel injection amount) when the ignition capabilities of both spark plugs 10a and 10b are normal, and thereby sets the fuel injection amount to be injected into the intake passage 11a so that it gradually decreases as the load on the engine 1 increases on the high load side and gradually increases as the load on the engine 1 decreases on the low load side, compared to the fuel injection amount to be injected into the intake passage 11a when it is determined that both spark plugs 10a and 10b are normal.

[0045] In the process of step S7, since neither the spark plugs 10a nor 10b has an abnormality, the fuel injection control unit 152 does not calculate the correction coefficient for the case where an abnormality has occurred in only one of the spark plugs 10a and 10b. This completes the process of step S7, and the current series of correction coefficient calculation processes ends. In this case, the fuel injection control unit 152 calculates the normal fuel injection amount (the fuel injection amount calculated from the basic fuel injection amount and the correction fuel injection amount) when the ignition capabilities of both the spark plugs 10a and 10b are normal.

[0046] In the internal combustion engine control device 50 of the above embodiment, the fuel supply control unit 152 is configured so that 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 amount of fuel supplied to the internal combustion engine 1 is reduced as the load increases on the high load side of the internal combustion engine 1, and increased as the load decreases on the low load side of the internal combustion engine 1, compared to the amount of fuel supplied to the internal combustion engine 1 when both the first spark plugs 10a, 10b and the second spark plugs 10b, 10a are in a normal state.By this, when an abnormality occurs in only one of the two spark plugs 10a, 10b provided in the internal combustion engine 1, a decrease in the output of the internal combustion engine 1 can be suppressed while various characteristics such as good exhaust gas characteristics can be ensured.

[0047] Furthermore, in the internal combustion engine control device 50 of this embodiment, 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 fuel supply control unit 152 reduces the amount of fuel supplied when both the first spark plugs 10a, 10b and the second spark plugs 10b, 10a are in a normal state in accordance with the rotation speed of the internal combustion engine 1, and decreases the amount of fuel supplied as the throttle opening increases on the side where the throttle opening of the internal combustion engine 1 is large, and increases the amount of fuel supplied as the throttle opening decreases on the side where the throttle opening is small.This makes it possible to more reliably suppress a decrease in the output of the internal combustion engine 1 while more reliably achieving various characteristics such as good exhaust gas characteristics when an abnormality occurs in only one of the two spark plugs 10a, 10b provided in the internal combustion engine 1.

[0048] 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]

[0049] As described above, the present invention provides an internal combustion engine control device that can suppress a decrease in the output of the internal combustion engine while ensuring various characteristics such as good exhaust gas characteristics when an abnormality occurs in only one of the two spark plugs provided in the internal combustion engine, and is expected to be widely applicable to internal combustion engine control devices for motorcycles due to its versatile and universal nature. [Explanation of symbols]

[0050] 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 internal combustion engine control device is characterized in that, 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 sets the amount of fuel supplied to the internal combustion engine so that it decreases as the load increases on the high load side of the internal combustion engine and increases as the load decreases on the low load side of the internal combustion engine, compared to the amount of fuel supplied to the internal combustion engine when both the first spark plug and the second spark plug are in a normal state.

2. 2. The internal combustion engine control device according to claim 1, wherein, when one of the first spark plug and the second spark plug is in the normal state and the other of the first spark plug and the second spark plug is in the abnormal state, the fuel supply control unit sets the amount of fuel supplied when both the first spark plug and the second spark plug are in the normal state in accordance with the rotation speed of the internal combustion engine, so as to decrease the amount of fuel supplied as the throttle opening becomes larger on the side where the throttle opening of the internal combustion engine is large, and to increase the amount of fuel supplied as the throttle opening becomes smaller on the side where the throttle opening is small.

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