Fire detection device

Abstract

A misfire determination device is provided, which determines misfire of the engine in a hybrid vehicle in which the engine is connected to the axle side via a torsion element, can suppress an increase in processing load, and can determine misfire with high accuracy even when resonance occurs in the torsion element. The ECU constituting the misfire determination device includes: an engine speed calculation unit, which calculates a calculated engine speed by calculation based on the motor speed and the total gear ratio between the first motor generator and the engine; a rotation deviation acquisition unit, which acquires a rotation deviation between the engine speed and the calculated engine speed; an average value acquisition unit, which obtains an average value of the rotation deviation between specified crankshaft angles; and a misfire determination unit, which subtracts the average value from the rotation deviation to obtain a rotation deviation after subtraction, and when the rotation deviation after subtraction exceeds a determination threshold, the misfire determination unit determines that the engine has misfired.

Description

Technical Field

[0001] The present invention relates to a misfire determination device, and more particularly to a misfire determination device for determining misfire of an engine in a hybrid vehicle equipped with an engine and an electric motor as driving force sources. Background Art

[0002] Currently, engine misfire determination is performed to prevent the deterioration of exhaust emissions due to engine misfire. On the other hand, in recent years, hybrid electric vehicles (HEV) and plug-in hybrid electric vehicles (PHEV) that can effectively improve the fuel consumption rate (fuel efficiency) of vehicles by using both an engine and an electric motor have been widely used.

[0003] However, generally, engine misfire determination is performed by comparing the engine rotation speed at each ignition cycle (i.e., based on the engine rotation fluctuation). However, in a hybrid vehicle where the engine is connected to the axle side via a torsional element such as a shock absorber, the torsion of the torsional element affects the engine rotation fluctuation, so it may be difficult to determine the engine misfire with high accuracy. In particular, when the torsional element causes resonance, the engine rotation vibration may not be able to distinguish between normal combustion and misfire.

[0004] Here, Patent Document 1 discloses a misfire determination system that determines misfire of an engine by taking into account the influence of resonance of a torsional element or the like.

[0005] In more detail, in the misfire determination system, the EFI-ECU measures the detection time of the front shaft speed (engine speed Ne) based on the synchronization signal, that is, the front time. On the other hand, the HV-ECU sets the motor time measured based on the synchronization signal as the calculation time of the rear shaft speed (input shaft speed Nd), that is, the rear time. Moreover, the EFI-ECU obtains the input shaft speed Nd and the rear time from the HV-ECU via the communication line, and calculates the resonance influence component Nde caused by the resonance on the engine speed Ne based on the engine speed Ne and the input shaft speed Nd that are closest to the front time and the rear time. Moreover, the misfire determination of the engine is performed based on the detection speed obtained by subtracting the resonance influence component Nde from the engine speed Ne.

[0006] Patent Document 1: Japanese Patent Application Publication No. 2015-174492

[0007] As described above, according to the misfire determination system described in Patent Document 1, even if there is a delay until the engine speed Ne and the input shaft speed Nd are acquired, the closest preceding and succeeding timings can be determined. Furthermore, misfire determination of the engine can be performed using the engine speed Ne and the input shaft speed Nd that are closest to the preceding and succeeding timings.

[0008] However, in the above-mentioned misfire determination system, it is necessary to synchronize the engine speed Ne and the input shaft speed Nd, and then calculate the resonance influence component Nde. More specifically, it is necessary to calculate the torsion angle θd based on the engine speed Ne and the input shaft speed Nd, calculate the resonance influence component Nden containing noise based on the torsion angle θd, remove the noise from the resonance influence component Nden containing noise using a high-pass filter, and thereby obtain the resonance influence component Nde. Furthermore, the resonance influence component Nde is subtracted from the engine speed Ne to obtain the determination speed, and the misfire determination is performed using the determination speed. Therefore, the processing load required for the misfire determination may increase. In particular, it is necessary to perform the misfire determination in each ignition cycle of each cylinder, that is, the execution frequency of the processing is high, and therefore there is a demand to suppress the increase in the processing load. Summary of the invention

[0009] The present invention is proposed to eliminate the above-mentioned problems, and its purpose is to provide a misfire determination device for determining misfire of an engine in a hybrid vehicle in which the engine is connected to the axle side via a torsional element, which can suppress an increase in processing load and can determine misfire with high accuracy even when resonance occurs in the torsional element.

[0010] The misfire determination device involved in the present invention determines misfire of the engine in a hybrid vehicle in which the engine is connected to the axle side via a torsion element and the axle and the electric motor are connected in a manner capable of transmitting torque, and is characterized by comprising: an engine speed acquisition unit that acquires the engine speed of the engine; a motor speed acquisition unit that acquires the motor speed of the electric motor; an engine speed calculation unit that calculates the calculated engine speed by calculation based on the motor speed and the total gear ratio between the electric motor and the engine; a rotation deviation acquisition unit that acquires the engine speed and the rotation deviation of the calculated engine speed; and a misfire determination unit that determines that the engine has misfired when the rotation deviation exceeds a determination threshold.

[0011] According to the misfire determination device involved in the present invention, the engine speed (rotational speed) and the motor speed (rotational speed) are obtained, and the calculated engine speed is calculated by calculation based on the motor speed and the total gear ratio between the motor and the engine. In addition, the rotation deviation between the engine speed and the calculated engine speed is obtained, and when the rotation deviation exceeds the determination threshold, it is determined that the engine misfires. That is, the deviation (comparison) between the directly obtained engine speed and the calculated engine speed calculated by calculation based on the speed of the motor set on the downstream side of the torsion element is obtained, thereby only the rotation deviation caused by misfire (reduction in engine torque) can be extracted. As a result, the increase in processing load can be suppressed, and misfire can be determined with high accuracy even when resonance occurs in the torsion element.

[0012] Particularly preferably, the misfire determination device of the present invention further comprises an average value obtaining unit for obtaining an average value of the rotational deviations between specified crankshaft angles, and subtracts the average value from the rotational deviations to obtain a rotational deviation after subtraction. When the rotational deviation after subtraction exceeds a determination threshold, the misfire determination unit determines that the engine has misfired.

[0013] In this case, the average value of the rotation deviation between the specified crankshaft angles is obtained, and the average value is subtracted from the rotation deviation to obtain the rotation deviation after subtraction. Moreover, when the rotation deviation after subtraction exceeds the judgment threshold, it is judged that the engine misfires. That is, first, the rotation deviation between the engine speed and the calculated engine speed is averaged between the specified crankshaft angles, and the potential deviation (deviation) between the engine speed and the calculated engine speed is calculated. Moreover, the average value (potential deviation) is subtracted from the rotation deviation to calculate the rotation deviation (instantaneous rotation deviation) after subtraction. Therefore, by removing the potential deviation (deviation) from the rotation deviation between the engine speed and the calculated engine speed, it is possible to extract a sudden rotation change such as a misfire, and it is possible to judge a misfire with high accuracy even in the resonance region.

[0014] In the misfire determination device according to the present invention, it is preferable that the region between the predetermined crank angles is set according to the resonance frequency of the torsional element.

[0015] This makes it possible to more appropriately calculate the potential deviation amount (deviation) between the engine speed and the calculated engine speed.

[0016] In the misfire determination device according to the present invention, preferably, the determination threshold is defined based on an engine speed and an engine load.

[0017] According to this, the determination threshold value can be set more appropriately.

[0018] In the misfire determination device according to the present invention, it is preferable that the determination threshold value is corrected according to the engine cooling water temperature.

[0019] However, the combustion of the engine deteriorates in a cold state. In this case, the determination threshold is corrected according to the water temperature, so that erroneous determination can be prevented and misfire can be determined with higher accuracy.

[0020] In the misfire determination device according to the present invention, preferably, after the engine is temporarily stopped, when the engine is restarted, the misfire determination unit provides a delay until the misfire determination is restarted.

[0021] However, combustion is relatively unstable immediately after the engine restarts. In this case, erroneous determination can be prevented by providing a delay when the engine restarts.

[0022] In the misfire determination device according to the present invention, preferably, the misfire determination unit performs misfire determination in an engine speed range where resonance of a torsional element is likely to occur.

[0023] According to this, since the misfire determination is performed only in the resonance region of the torsion element (the engine rotation region where the resonance occurs), it is possible to further suppress an increase in the processing load.

[0024] In the misfire determination device involved in the present invention, preferably, the misfire determination unit determines whether the engine has misfired based on whether the rotation deviation after the subtraction operation exceeds a determination threshold value, and on this basis, determines whether the engine has misfired based on whether the difference between the engine speed at the crankshaft angle corresponding to the ignition timing and the engine speed before the crankshaft angle reaches a prescribed crankshaft angle exceeds a prescribed threshold value, and when the engine is determined to be misfired by any one method or both methods, it is determined that the engine has misfired.

[0025] In this way, by combining the method of determining misfire based on the rotation deviation of the engine and the motor and the method of determining misfire based on the rotation variation of the engine, the accuracy of misfire determination can be improved in the entire operating range (i.e., the range excluding the resonance range of the torsional element).

[0026] In the misfire determination device according to the present invention, preferably, the misfire determination unit accumulates a count value for counting the number of misfire determinations each time the engine misfire is determined, and determines a misfire abnormality when the count value reaches a predetermined value.

[0027] This can prevent erroneous determination and, when the degree of misfire reaches a level that may adversely affect exhaust gas emissions, can determine that the misfire is abnormal.

[0028] Effects of the Invention

[0029] According to the present invention, in a hybrid vehicle in which an engine is connected to an axle via a torsional element, an increase in processing load can be suppressed and misfire can be determined with high accuracy even when resonance occurs in the torsional element. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic diagram showing the structure of a power unit of a hybrid vehicle equipped with a misfire determination device according to the embodiment, and a block diagram showing the structure of a control system thereof.

[0031] Figure 2 It is a diagram showing the configuration of a misfire determination device according to an embodiment and an engine to which the misfire determination device is applied.

[0032] Figure 3 This is a diagram for explaining misfire determination by the misfire determination device according to the embodiment (FIG. 1).

[0033] Figure 4 This is a diagram for explaining misfire determination by the misfire determination device according to the embodiment (FIG. 2).

[0034] Figure 5 This is a flowchart showing the flow of a misfire determination process performed by the misfire determination device according to the embodiment.

[0035] Description of the label

[0036] 1 misfire determination device, 10 engine, 11 first motor generator, 12 second motor generator, 20 flywheel damper (torsion element), 30 driving force splitting mechanism, 40 driving reduction gear mechanism, 41 motor reduction gear, 43 driving reduction gear, 50 impeller shaft, 51 transfer clutch, 52 rear differential, 60 front drive shaft, 62 front differential, 70 CAN, 80 HEV-CU, 81 ECU, 81a engine speed calculation unit, 81b rotation deviation acquisition unit, 81c average value acquisition unit, 81d misfire determination unit, 82 PCU, 91 accelerator pedal sensor, 92 throttle opening sensor, 93 G sensor (acceleration sensor), 94 vehicle speed sensor (wheel speed sensor), 95 speed sensor, 97, 98 resolver, 112 injector, 113 electronically controlled throttle valve, 114 air flow meter, 117 spark plug, 119 air-fuel ratio sensor (LAF sensor), 132 cam angle sensor, 133 crankshaft angle sensor, 133a timing rotor, 134 water temperature sensor. DETAILED DESCRIPTION

[0037] Below, the preferred embodiment of the present invention is described in detail with reference to the accompanying drawings. In addition, in the accompanying drawings, the same reference numerals are used for the same or equivalent parts. In addition, in each figure, the same reference numerals are marked for the same elements and repeated descriptions are omitted.

[0038] First, use Figure 1 and Figure 2 The configuration of the misfire determination device 1 according to the embodiment will be described. Figure 1 It is a schematic diagram showing the structure of a power unit of a hybrid vehicle equipped with the misfire determination device 1 and a block diagram showing the structure of its control system. Figure 2 1 is a diagram showing the configuration of a misfire detection device 1 and an engine 10 to which the misfire detection device 1 is applied. Here, a case where the misfire detection device 1 is mounted on a series-parallel hybrid electric vehicle (HEV) will be described as an example.

[0039] First, refer to Figure 1 The structure of the power unit of a hybrid vehicle is described. A power split mechanism 30 is connected to the crankshaft 10a of the engine 10 (described in detail later) via a flywheel damper 20 (equivalent to the torsion element described in the claims) that absorbs the rotational fluctuations of the engine 10 and a pair of gears 21. The power split mechanism 30 is connected to a drive mechanism 15 composed of a plurality of gears, shafts, etc., and transmitting torque between the drive wheels, and a first motor generator (MG) 11 (equivalent to the motor described in the claims). The power split mechanism 30 has, for example, a planetary gear mechanism composed of a sun gear 30a, a ring gear 30b, a pinion gear 30c, and a planetary carrier 30d, which splits the driving torque generated by the engine 10 and transmits it to the drive mechanism 15 and the first motor generator 11.

[0040] More specifically, the planetary carrier 30d is connected to the crankshaft 10a of the engine 10 via the flywheel damper 20 and a pair of gears 21. The sun gear 30a is connected to the first motor generator 11. On the other hand, the ring gear 30b is connected to the impeller shaft (equivalent to the rear wheel output shaft, the axle described in the claims) 50 constituting the drive mechanism 15 via a pair of gears (counter gears) 31, and is further connected to the front drive shaft (equivalent to the front wheel output shaft, the axle described in the claims) 60 via a driving reduction gear 43.

[0041] When the first motor generator 11 functions as a generator, the power distribution mechanism 30 distributes the torque (driving force) from the engine 10 input from the planetary carrier 30d to the sun gear 30a and the ring gear 30b according to the gear ratio of the two. On the other hand, when the first motor generator 11 functions as a motor (electric motor), the power distribution mechanism 30 outputs the torque from the engine 10 input from the planetary carrier 30d and the torque from the first motor generator 11 input from the sun gear 30a to the ring gear 30b. The torque input to the ring gear 30b is output to the impeller shaft 50 constituting the drive mechanism 15 via a pair of gears (reverse gears) 31, and is further output to the forward drive shaft 60 via the driving reduction gear 43.

[0042] On the other hand, the second motor generator (MG) 12 (equivalent to the electric motor described in the claims) is also connected to the drive mechanism 15. More specifically, the second motor generator 12 is connected to the impeller shaft 50 via the motor reduction gear 41. In addition, the second motor generator 12 is connected to the front drive shaft 60 via the drive reduction gear mechanism 40 composed of the motor reduction gear 41 and the drive reduction gear 43. The front drive shaft 60 transmits torque to the front wheel. In addition, the impeller shaft 50 transmits torque to the rear wheel.

[0043] The first motor generator 11 and the second motor generator 12 are configured as synchronous motor generators having both the function of a motor that converts supplied electric power into mechanical power and the function of a generator that converts input mechanical power into electric power. That is, the first motor generator 11 and the second motor generator 12 respectively operate as motors that generate driving torque when driving the vehicle, and operate as generators during regeneration. In addition, the first motor generator 11 mainly operates as a generator, and the second motor generator 12 mainly operates as a motor.

[0044] The driving reduction gear mechanism 40 includes a motor reduction gear 41 and a driving reduction gear 43. The motor reduction gear 41 is composed of a planetary gear, and the reduction gear 43 is composed of, for example, a spur gear (or a helical gear).

[0045] More specifically, the motor reduction gear 41 has a planetary gear mechanism composed of, for example, a sun gear 41a, a ring gear 41b, a pinion gear 41c, and a planetary carrier 41d. When the second motor generator 12 functions as a motor, the motor reduction gear 41 reduces the rotation transmitted from the second motor generator 12 (increases the torque) and outputs it from the planetary carrier 41d. On the other hand, the motor reduction gear 41 accelerates the rotation caused by the torque (driving force) input to the planetary carrier 41d (reduces the torque) and outputs it from the sun gear 41a, thereby causing the second motor generator 12 to function as a generator.

[0046] The front drive shaft 60 is connected to the driving reduction gear mechanism 40 and the driving wheel ( Figure 1 In more detail, the torque transmitted to the second motor generator 12 or the like of the front drive shaft 60 is transmitted to the front differential (hereinafter also referred to as the "front differential") 62. The front differential 62 is, for example, a bevel gear type differential device. The torque from the front differential 62 is transmitted to the left front wheel (not shown) via the left front wheel drive shaft, and is transmitted to the right front wheel (not shown) via the right front wheel drive shaft.

[0047] On the other hand, the impeller shaft 50 transmits torque to the rear wheel. A transfer clutch 51 is interposed on the impeller shaft 50 to adjust the torque transmitted to the rear wheel side. The transfer clutch 51 controls the fastening force (i.e., the torque distribution rate to the rear wheel) according to the driving state of the four wheels (e.g., the slip state of the front wheel, etc.), the engine torque, etc. Therefore, the torque transmitted to the second motor generator 12 and the like of the impeller shaft 50 is distributed according to the fastening force of the transfer clutch 51 and is also transmitted to the rear wheel side.

[0048] More specifically, the torque transmitted to the impeller shaft 50 and adjusted (distributed) by the transfer clutch 51 is transmitted to the rear differential (hereinafter also referred to as "rear differential") 52. The left rear wheel drive shaft and the right rear wheel drive shaft (not shown) are connected to the rear differential 52. The driving force from the rear differential 52 is transmitted to the left rear wheel (not shown) via the left rear wheel drive shaft, and is transmitted to the right rear wheel (not shown) via the right rear wheel drive shaft.

[0049] With the above configuration, the vehicle (AWD HEV vehicle) according to the present embodiment can drive the front and rear wheels (vehicle) using the power of both the engine 10 and the second motor generator 12. In addition, depending on the driving conditions, for example, it is possible to switch between driving based on the second motor generator 12 alone (EV driving) and driving based on the engine 10 and the second motor generator 12. Furthermore, it is also possible to generate electricity using the second motor generator 12 and the like.

[0050] The engine 10 , the second motor generator 12 , and the first motor generator 11 , which are driving force sources of the vehicle, are centrally controlled by a hybrid vehicle control unit (hereinafter referred to as “HEV-CU”) 80 .

[0051] HEV-CU80 is configured to include a microprocessor for performing calculations, an EEPROM for storing programs for causing the microprocessor to execute various processes, a RAM for storing various data such as calculation results, a backup RAM for maintaining the stored contents, and an input / output I / F.

[0052] For example, various sensors including an accelerator pedal sensor 91 for detecting the amount of depression of the accelerator pedal, a throttle opening sensor 92 for detecting the opening of the throttle valve, a G sensor (acceleration sensor) 93 for detecting the front, rear, and left and right accelerations of the vehicle, a vehicle speed sensor 94 for detecting the speed of the wheels, a rotation speed sensor 95 for detecting the rotation speed of the front drive shaft 60, a resolver 97 for detecting the rotation speed (rotation speed) of the first motor generator 11, and a resolver 98 for detecting the rotation speed (rotation speed) of the second motor generator 12 are connected to the HEV-CU 80. In addition, the resolver 97 and the resolver 98 each function as a motor rotation speed acquisition unit described in the claims.

[0053] In addition, the HEV-CU80 is connected to the engine control unit (hereinafter referred to as "ECU") 81 that controls the engine 10, the combined control unit (hereinafter referred to as "VDCU") 85 that suppresses the side slip of the vehicle and improves the driving stability, etc. via the CAN (Controller Area Network) 70 in a manner that can communicate with each other. The HEV-CU80 receives various information such as the engine speed and the brake operation amount from the ECU81 and the VDCU85 via the CAN70. On the other hand, the HEV-CU80 sends various information such as the speed (rotation speed) of the first motor generator 11 and the speed (rotation speed) of the second motor generator 12 to the ECU81 via the CAN70.

[0054] Based on the above-mentioned various information obtained, the HEV-CU 80 controls the driving of the engine 10, the second motor generator 12, and the first motor generator 11 in a unified manner. The HEV-CU 80 obtains and outputs the requested output of the engine 10 and the torque command values ​​of the second motor generator 12 and the first motor generator 11 based on, for example, the accelerator pedal opening (the driver's requested driving force), the vehicle's operating state, and the state of charge (SOC) of the high-voltage battery (hereinafter, also referred to as "battery") 90.

[0055] The power control unit (hereinafter referred to as "PCU") 82 drives the second motor generator 12 and the first motor generator 11 based on the above-mentioned torque command value and via the inverter 82a. The PCU 82 has an inverter 82a that converts the DC power of the high-voltage battery 90 into three-phase AC power and supplies it to the second motor generator 12 and the first motor generator 11. As described above, the PCU 82 drives the second motor generator 12 and the first motor generator 11 based on the torque command value received from the HEV-CU 80 and via the inverter 82a. On the other hand, the inverter 82a converts the AC voltage generated by the second motor generator 12 into a DC voltage during regeneration to charge the high-voltage battery 90.

[0056] In addition, the ECU 81 adjusts the opening of the electronically controlled throttle valve 113, for example, based on the above-mentioned request output. Figure 2 The configurations of the misfire detection device 1 and the engine 10 to which the misfire detection device 1 is applied will be described in detail.

[0057] The engine 10 may be of any structure, for example, a horizontally opposed 4-cylinder gasoline engine. In addition, the engine 10 is an in-cylinder injection type engine that directly injects fuel into the cylinder (in-cylinder). In the engine 10, the air sucked from the air filter 116 is throttled by an electronically controlled throttle valve (hereinafter, also referred to as "throttle valve") 113 provided in the intake pipe 115, and the air is sucked into each cylinder formed in the engine 10 through the intake manifold 111. Here, the amount of air sucked from the air filter 116 is detected by an air flow meter 114 arranged between the air filter 116 and the throttle valve 113. In addition, a vacuum sensor 130 for detecting the pressure (intake manifold pressure) in the intake manifold 111 is arranged inside the converging portion (regulating tank) constituting the intake manifold 111. In addition, a throttle opening sensor 92 for detecting the opening of the throttle valve 113 is arranged in the throttle valve 113.

[0058] The cylinder head is provided with an intake port 122 and an exhaust port 123 for each cylinder. Figure 2Only a single group is shown in FIG. 1 ). An intake valve 124 and an exhaust valve 125 are provided at each intake port 122 and exhaust port 123, respectively, for opening and closing the intake port 122 and exhaust port 123. A variable valve timing mechanism 126 is arranged between the intake camshaft and the intake cam pulley for driving the intake valve 124. That is, the variable valve timing mechanism 126 causes the intake cam pulley and the intake camshaft to rotate relative to each other and continuously changes the rotation phase (displacement angle) of the intake camshaft relative to the crankshaft 10a, so that the valve timing (opening and closing timing) of the intake valve 124 is advanced or delayed. The opening and closing timing of the intake valve 124 is variably set by using the variable valve timing mechanism 126 according to the engine operating state.

[0059] Similarly, a variable valve timing mechanism 127 is disposed between the exhaust camshaft and the exhaust cam pulley. The variable valve timing mechanism 127 causes the exhaust cam pulley and the exhaust camshaft to rotate relative to each other and continuously changes the rotation phase (displacement angle) of the exhaust camshaft relative to the crankshaft 10a, thereby advancing or retarding the valve timing (opening and closing timing) of the exhaust valve 125. The opening and closing timing of the intake valve 125 is variably set by the variable valve timing mechanism 127 according to the engine operating state.

[0060] An injector 112 for injecting fuel into the cylinder is mounted on each cylinder of the engine 10. The injector 112 injects the fuel pressurized by a high-pressure fuel pump (not shown) directly into the combustion chamber of each cylinder.

[0061] In addition, a spark plug 117 for igniting the mixed gas and an igniter-built-in coil 121 for applying a high voltage to the spark plug 117 are mounted on the cylinder head of each cylinder. In each cylinder of the engine 10, the mixed gas of the intake air and the fuel injected by the injector 112 is combusted by ignition by the spark plug 117. The exhaust gas after the combustion is discharged through the exhaust pipe 118.

[0062] In this embodiment, the exhaust pipe 118 adopts the following 4-2-1 layout in order to avoid interference with exhaust, that is, the first cylinder (#1) and the second cylinder (#2), the third cylinder (#3) and the fourth cylinder (#4) are first merged (collected), and then merged into one cylinder. In addition, a 4-1 layout may be adopted instead of the 4-2-1 layout.

[0063] An air-fuel ratio sensor 119 is installed downstream of the junction of the exhaust pipe 118 and upstream of the exhaust purification catalyst 120 described later. As the air-fuel ratio sensor 119, a linear air-fuel ratio sensor (LAF sensor) is used which can output a signal corresponding to the oxygen concentration and the unburned gas concentration in the exhaust gas (i.e., a signal corresponding to the air-fuel ratio of the mixed gas) and can linearly detect the air-fuel ratio.

[0064] An exhaust gas purification catalyst 120 is arranged downstream of the LAF sensor 119. The exhaust gas purification catalyst 120 is a three-way catalyst that simultaneously oxidizes hydrocarbons (HC) and carbon monoxide (CO) in the exhaust gas and reduces nitrogen oxides (NOx), thereby purifying harmful gas components in the exhaust gas into harmless carbon dioxide (CO2), water vapor (H2O) and nitrogen (N2).

[0065] In addition to the above-mentioned air flow meter 114, LAF sensor 119, vacuum sensor 130, and throttle opening sensor 92, a cam angle sensor 132 for performing cylinder discrimination of the engine 10 is also installed near the camshaft of the engine 10. In addition, a crank angle sensor 133 for detecting the rotation position of the crankshaft 10a (rotation angular velocity and rotation speed obtained from the time change of the rotation position) is installed near the crankshaft 10a of the engine 10. Here, a timing rotor 133a is installed at the end of the crankshaft 10a, for example, with 34 teeth with protrusions formed at intervals of 10°, which lacks two teeth. The crank angle sensor 133 detects the presence or absence of the protrusion of the timing rotor 133a to detect the rotation position of the crankshaft 10a. As the cam angle sensor 132 and the crank angle sensor 133, for example, an electromagnetic pickup type structure is used. In addition, the crank angle sensor 133 functions as an engine speed acquisition unit described in the claims.

[0066] The above sensors are connected to the ECU 81. In addition, various sensors such as a water temperature sensor 134 for detecting the temperature of the cooling water of the engine 10 are also connected to the ECU 81. In addition, the ECU 81 receives information such as the requested output, the rotation speed (rotation speed) of the first motor generator 11, the rotation speed (rotation speed) of the second motor generator 12, and the accelerator pedal opening from the HEV-CU 80 via the CAN 70.

[0067] The ECU 81 is configured to include a microprocessor for performing calculations, an EEPROM for storing programs for causing the microprocessor to execute various processes, a RAM for storing various data such as calculation results, a backup RAM for retaining the stored contents by a battery, an input / output I / F, etc. In addition, the ECU 81 includes an injector driver for driving the injector 112, an output circuit for outputting an ignition signal, and a motor driver for driving the electric motor 113a for opening and closing the electronically controlled throttle valve 113, etc.

[0068] In the ECU 81, the cylinder is identified based on the output of the cam angle sensor 132, and the rotational angular velocity and the engine speed are obtained based on the output of the crank angle sensor 133. In addition, in the ECU 81, various information such as the intake air amount, the intake pipe negative pressure, the air-fuel ratio of the mixed gas, and the water temperature of the engine 10 are obtained based on the detection signals input from the above-mentioned various sensors. Moreover, the ECU 81 controls various devices such as the fuel injection amount, the ignition timing, and the throttle valve 113 based on the request output from the HEV-CU 80 and the above-mentioned various information obtained, thereby controlling the engine 10.

[0069] In particular, the ECU 81 has a function of accurately determining misfire even when the flywheel damper 20 resonates while suppressing an increase in processing load. Therefore, the ECU 81 has an engine speed calculation unit 81a, a rotation deviation acquisition unit 81b, an average value acquisition unit 81c, and a misfire determination unit 81d in terms of functions. In the ECU 81, the microprocessor executes a program stored in an EEPROM or the like, thereby realizing the functions of the engine speed calculation unit 81a, the rotation deviation acquisition unit 81b, the average value acquisition unit 81c, and the misfire determination unit 81d.

[0070] The engine speed calculation unit 81a calculates the motor speed of the first motor generator 11 (or the second motor generator 12) received from the HEV-CU 80 and the total gear ratio ( Figure 1 In the example, the gear ratio of the gear pair 21 and the power split mechanism 30 (the sun gear 30a and the pinion gear 30c) is calculated and the engine speed (calculated engine speed) is calculated. In addition, it can be formed into a structure in which the calculation is performed on the HEV-CU80 side and the calculated engine speed is obtained via CAN70. That is, the engine speed calculation unit 81a functions as an engine speed calculation unit described in the claims. In addition, the calculated engine speed is output to the rotation deviation acquisition unit 81b.

[0071] The rotation deviation acquisition unit 81b acquires the rotation deviation between the engine speed and the calculated engine speed. That is, the rotation deviation acquisition unit 81b functions as a rotation deviation acquisition means described in the claims. Furthermore, the acquired rotation deviation is output to the average value acquisition unit 81c.

[0072] The average value acquisition unit 81c obtains the moving average value (rotation deviation average value) of the rotation deviation of the engine speed and the calculated engine speed between the specified crankshaft angles (intervals). That is, the average value acquisition unit 81c functions as the average value acquisition unit described in the claims. In addition, the specified crankshaft angle interval (i.e., the number of data) for implementing the moving average is set according to the resonance frequency of the flywheel damper 20. In addition, preferably, the higher the speed of the engine 10, the larger the specified crankshaft angle interval (number of data). The reason is that if the engine speed changes, the ignition interval (time) changes, but the resonance frequency does not change, so the number of ignitions (number of data) required to absorb the resonance wave changes. In addition, the moving average value of the rotation deviation is output to the misfire determination unit 81d.

[0073] The misfire determination unit 81d subtracts the moving average of the rotation deviation from the rotation deviation to obtain the rotation deviation after subtraction. When the rotation deviation after subtraction exceeds the determination threshold, the misfire determination unit 81d determines that the engine 10 has misfired. That is, the misfire determination unit 81d functions as a misfire determination unit described in the claims. Here, the misfire determination unit 81d performs the above-mentioned misfire determination in the engine speed range (e.g., 1500 to 2500 rpm) where the resonance of the flywheel damper 20 may occur.

[0074] In order to reliably determine misfire, a determination threshold for determining misfire is defined based on, for example, the engine speed and the engine load (calculated based on, for example, the intake air amount). The reason for this is that if the engine speed changes, the output mode of the rotation deviation changes due to the influence of the inertia force, and if the output torque of the engine 10 changes, the variation amount during misfire changes. Here, the following correspondence map (determination threshold correspondence map) is stored in the EEPROM of the ECU 81, that is, the relationship between the engine speed, the engine load (for example, the intake air amount) and the determination threshold is stored in the correspondence map. In the misfire determination unit 81d, the determination threshold is retrieved from the determination threshold correspondence map based on the engine speed and the engine load (intake air amount) to obtain the determination threshold.

[0075] In addition, in order to prevent erroneous determination, the determination threshold is corrected according to the cooling water temperature of the engine 10 (water temperature correction). The reason is that the atomization of the fuel deteriorates (i.e., the combustion deteriorates) in the cooling state, and the engine speed is likely to change. And from the viewpoint of preventing erroneous determination, it is preferred that after the engine 10 is temporarily stopped, when the engine 10 is restarted (for example, when recovering from fuel cutoff, idling stop, etc.), the misfire determination unit 81d sets a predetermined delay time until the misfire determination is re-executed. The reason is that, for example, just after recovery from fuel cutoff, the combustion condition is likely to deteriorate, and there is a tendency for the rotation deviation to increase.

[0076] Then, the misfire determination unit 81d accumulates a count value for counting the number of misfire determinations each time the engine 10 is determined to be misfired, and determines that there is a misfire abnormality when the count value reaches a predetermined value.

[0077] Furthermore, as described above, the misfire determination unit 81d determines whether the engine 10 has misfired based on whether the rotational deviation after the subtraction operation exceeds the determination threshold value. On this basis, it is preferred to determine whether the engine 10 has misfired based on whether the difference between the engine speed at the crank angle corresponding to the ignition timing and the engine speed before the crank angle reaches a specified crank angle (for example, before 180°, 360°, 720°CA) (i.e., the rotational variation of the engine 10) exceeds a specified threshold value. In the case where it is determined that the engine 10 has misfired by any one method or both methods, it is determined that the engine 10 has misfired.

[0078] Below, refer to Figure 3 to Figure 5 Next, the operation of the misfire determination device 1 will be described. Figure 3 and Figure 4 1 and 2 are diagrams for explaining the misfire determination of the misfire determination device 1. Figure 3 The horizontal axis is time (moment), and the vertical axis is, from the top, the real-time calculated engine speed (rpm), the averaged calculated engine speed (rpm) at each ignition, the engine speed (rpm), the rotation deviation (rpm), and the engine cylinder count value. Similarly, Figure 4 The horizontal axis in the figure is time (moment), and the vertical axis is rotation deviation (rpm), moving average of rotation deviation (rpm), rotation deviation (rpm) after subtracting moving average, and engine cylinder count value in order from the top. Here, the engine cylinder count value is a count value accumulated (increased) every time the ignition timing of the engine 10 is reached (for example, every 180°C for a 4-cylinder engine), indicating which cylinder is the ignition cylinder. Figure 51 is a flowchart showing the processing flow of the misfire determination process of the misfire determination device 1. This process is repeatedly executed mainly at a predetermined timing in the ECU 81.

[0079] First, in Figure 5 In step S100, the engine speed and the motor speed are read. Next, in step S102, it is determined whether the engine speed is in the engine speed range (e.g., 1500 to 2500 rpm) where the flywheel damper 20 resonates. Here, if the engine speed is in the engine speed range where resonance occurs, the process proceeds to step S104. On the other hand, if the engine speed is not in the engine speed range where resonance occurs, the process is temporarily skipped.

[0080] In step S104, it is determined whether a time greater than or equal to a predetermined time has passed after the engine 10 is restarted. If a time greater than or equal to the predetermined time has passed, the process proceeds to step S106. On the other hand, if a time greater than or equal to the predetermined time has not passed, the process is temporarily skipped.

[0081] In step S106, first, the real-time calculated engine speed is calculated based on the real-time motor speed of the first motor generator 11 and the total gear ratio between the first motor generator 11 and the engine 10 (refer to Figure 3 The real-time calculated engine speed is synchronized with the engine cylinder count value, that is, the calculated engine speed for misfire determination is averaged each time the engine 10 is ignited (for example, every 180°C in the case of a 4-cylinder engine) (see Figure 3 Similarly, the real-time engine speed is synchronized with the engine cylinder count value, that is, the engine speed for misfire determination is averaged each time the engine 10 is ignited (for example, every 180°C for a 4-cylinder engine) (see Figure 3 The dotted line of the third layer in FIG.

[0082] Then, in step S108, the deviation between the engine speed calculated in step S106 and the calculated engine speed is obtained (see Figure 3 Layer 4 in Figure 4 Next, in step S110, the moving average value of the rotation deviation between the predetermined crankshaft angles (the average rotation difference generated before and after the flywheel damper 20) is calculated (refer to Figure 4 More specifically, Figure 4 As shown, for the interval before and after the reference ignition (in Figure 4In the example, the moving average value of the interval (1260°C A)) containing the three points before and after is calculated.

[0083] Next, in step S112, the moving average of the rotation deviation calculated in step S110 is subtracted from the rotation deviation to calculate the rotation deviation after the subtraction (see Figure 4 Then, in step S114, the above-mentioned judgment threshold correspondence map is searched according to the engine speed and the engine load (intake air amount) to obtain the judgment threshold. In addition, in step S114, the water temperature correction is performed according to the cooling water temperature for the obtained judgment threshold.

[0084] Then, in step S116, it is determined whether the absolute value of the rotation deviation after subtraction is greater than the corrected determination threshold. Here, if the absolute value of the rotation deviation after subtraction is less than or equal to the corrected determination threshold, after determining that it is normal in step S118, this process is temporarily skipped. On the other hand, if the absolute value of the rotation deviation after subtraction is greater than the corrected determination threshold, the process proceeds to step S120.

[0085] In step S120, the count value for counting the number of misfire determinations is incremented (accumulated). Furthermore, in step S122, it is determined whether the count value has reached a prescribed value. Here, if the count value has not reached the prescribed value, this process is temporarily skipped. On the other hand, if the count value has reached the prescribed value, it is determined in step S124 that it is a misfire abnormality, and this process is then skipped.

[0086] Misfire determination is performed in the above manner. In addition, as described above, preferably, whether the engine 10 has misfired is determined based on whether the rotation deviation after subtraction exceeds a determination threshold, and on this basis, whether the engine 10 has misfired is determined based on whether the difference between the engine speed at a crank angle corresponding to the ignition timing and the engine speed before reaching a predetermined crank angle (for example, before 180°, 360°, 720°CA) relative to the crank angle (i.e., the rotation variation of the engine 10) exceeds a predetermined threshold, and when the engine 10 is determined to have misfired by any one method or both methods, it is determined that the engine 10 has misfired.

[0087] As described in detail above, according to the present embodiment, the engine speed (rotational speed) and the motor speed (rotational speed) are acquired, and the calculated engine speed is calculated based on the motor speed and the total gear ratio between the first motor generator 11 and the engine 10. Furthermore, the rotation deviation between the engine speed and the calculated engine speed is acquired, and when the rotation deviation exceeds the determination threshold, it is determined that the engine 10 is misfiring. That is, the deviation between the directly acquired engine speed and the calculated engine speed calculated based on the speed of the first motor generator 11 provided on the downstream side of the flywheel damper 20 is acquired (compared), thereby only the rotation deviation caused by misfiring (reduction in engine torque) can be extracted. As a result, the increase in processing load can be suppressed, and even when the flywheel damper 20 generates resonance, misfiring can be determined with high accuracy.

[0088] In particular, according to the present embodiment, a moving average value of the rotation deviation between specified crank angles (intervals) is obtained, and a subtraction operation is performed to subtract the moving average value from the rotation deviation to obtain the rotation deviation after the subtraction operation. Furthermore, when the rotation deviation after the subtraction operation exceeds the determination threshold, it is determined that the engine 10 is misfiring. That is, first, a moving average is performed on the rotation deviation between the engine speed and the calculated engine speed between specified crank angles, and a potential deviation amount (deviation) between the engine speed and the calculated engine speed is calculated. Furthermore, a subtraction operation is performed to subtract the moving average value (potential deviation amount) from the rotation deviation, thereby calculating the rotation deviation (instantaneous rotation deviation) after the subtraction operation. Therefore, by removing the potential deviation amount (deviation) from the rotation deviation between the engine speed and the calculated engine speed, it is possible to extract a rotation change that occurs suddenly, such as a misfire, and it is possible to determine a misfire with high accuracy even in a resonance region.

[0089] According to the present embodiment, the predetermined crank angle interval (section) is set according to the resonance frequency of the flywheel damper 20, so that the potential deviation amount (deviation) between the engine speed and the calculated engine speed can be calculated more appropriately.

[0090] According to the present embodiment, the determination threshold is defined based on the engine speed and the engine load, so that the determination threshold can be set more appropriately.

[0091] However, the combustion of the engine 10 deteriorates in a cold state. According to the present embodiment, since the determination threshold is corrected according to the water temperature, it is possible to prevent erroneous determination and determine misfire with higher accuracy.

[0092] However, combustion is relatively unstable immediately after the restart of the engine 10. According to the present embodiment, a delay is provided when the engine 10 is restarted, thereby preventing erroneous determination.

[0093] In addition, according to the present embodiment, the misfire determination is performed in the engine speed region where the resonance of the flywheel damper 20 may occur. Therefore, the misfire determination can be performed only in the resonance region of the flywheel damper 20 (engine rotation region where the resonance occurs), so the increase in the processing load can be further suppressed.

[0094] According to the present embodiment, the misfire is determined by combining the method of determining misfire based on the rotational deviation between the engine 10 and the first motor generator 11 and the method of determining misfire based on the rotational variation of the engine 10, thereby being able to improve the accuracy of misfire determination in the entire operating range (i.e., even in the region excluding the resonance region of the torsional element).

[0095] In addition, according to the present embodiment, each time the engine 10 is determined to be misfired, the count value for counting the number of misfire determinations is accumulated, and when the count value reaches a predetermined value, it is determined that there is a misfire abnormality. Therefore, it is possible to prevent erroneous determinations, and when the degree of misfire reaches a degree that may adversely affect exhaust emissions, it can be determined that there is a misfire abnormality.

[0096] The embodiments of the present invention are described above, but the present invention is not limited to the above embodiments, and various modifications can be implemented. For example, in the above embodiments, the misfire determination device 1 involved in the present invention is applied to a series-parallel hybrid vehicle (HEV) as an example, but it can also be applied to different forms of hybrid vehicles (for example, parallel hybrid vehicles, etc.) and plug-in hybrid vehicles (PHEV) that can be charged from the outside. In addition, in the above embodiments, there are two motors (a first motor generator 11 and a second motor generator 12), but the number of motors is not limited to two (two motors), and can be one (one motor), or can be greater than or equal to three (three motors). Similarly, the structure of the drive system composed of multiple gears and shafts is not limited to the above embodiments.

[0097] In addition, in the above-mentioned embodiment, the case where the misfire determination device 1 involved in the present invention is applied to a 4-cylinder engine is described as an example, but the present invention is not limited to a 4-cylinder engine. In addition, the present invention is not limited to a horizontally opposed engine, and can also be applied to an inline engine, a V-type engine, etc. Similarly, in the above-mentioned embodiment, the case where the present invention is applied to an in-cylinder injection engine is described as an example, but the present invention can also be applied to a port injection engine, etc.

[0098] In addition, the system structure of controllers such as HEV-CU80 and ECU81, and the functional division of each controller are not limited to the above-mentioned embodiment. In addition, in the above-mentioned embodiment, the case where the present invention is applied to an AWD vehicle (all wheel drive vehicle) is described as an example, but the present invention can also be applied to, for example, a 2WD vehicle (FF vehicle, FR vehicle).

Claims

1. A misfire determination device, in a hybrid vehicle in which an engine is connected to an axle side via a torsion element, and the axle and an electric motor are connected in a torque-transmittable manner, the misfire determination device determining misfire of the engine, The misfire determination device is characterized by comprising: an engine speed acquisition unit, which acquires the engine speed of the engine; A motor speed acquisition unit, which acquires the motor speed of the motor; an engine speed calculation unit for calculating the calculated engine speed by calculation based on the motor speed and the total gear ratio between the motor and the engine; a rotation deviation obtaining unit, which obtains a rotation deviation between the engine speed and the calculated engine speed; as well as The misfire determination unit determines that the engine misfires when the rotation deviation exceeds a determination threshold.

2. The misfire determination device according to claim 1, characterized in that: The device further comprises an average value obtaining unit for obtaining an average value of the rotation deviation between predetermined crankshaft angles. The misfire determination unit determines that the engine misfires when a subtracted rotation deviation is obtained by subtracting the average value from the rotation deviation and when the subtracted rotation deviation exceeds the determination threshold.

3. The misfire determination device according to claim 2, characterized in that: The interval between the predetermined crank angles is set according to the resonance frequency of the torsional element.

4. The misfire determination device according to claim 2 or 3, characterized in that: The determination threshold is specified according to the engine speed and the engine load.

5. The misfire determination device according to claim 2 or 3, characterized in that: The determination threshold is corrected according to a cooling water temperature of the engine.

6. The misfire determination device according to claim 2 or 3, characterized in that: The misfire determination unit sets a delay until misfire determination is re-executed when the engine is restarted after the engine is temporarily stopped.

7. The misfire determination device according to claim 2 or 3, characterized in that: The misfire determination unit performs misfire determination in an engine speed range where resonance of the torsion element is likely to occur.

8. The misfire determination device according to claim 2 or 3, characterized in that: The misfire determination unit determines whether the engine has misfired based on whether the rotational deviation after the subtraction exceeds the determination threshold value, and on this basis determines whether the engine has misfired based on whether a difference between an engine speed at a crank angle corresponding to an ignition timing and an engine speed before the crank angle reaches a prescribed crank angle exceeds a prescribed threshold value, and when the engine is determined to have misfired by any one method or both methods, the engine is determined to have misfired.

9. The misfire determination device according to claim 2 or 3, characterized in that: The misfire determination unit accumulates a count value for counting the number of misfire determinations each time the engine misfire is determined, and determines that there is a misfire abnormality when the count value reaches a predetermined value.

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