JP5772328B2 - Vehicle and internal combustion engine misfire determination method - Google Patents

Description

  The present invention relates to a technique for suppressing deterioration in determination accuracy of misfire determination of an internal combustion engine.

  When the vehicle is traveling on a rough road that causes fluctuations in the rotation of the internal combustion engine, the accuracy of determining whether or not misfire has occurred in the internal combustion engine may deteriorate. For example, Japanese Patent Application Laid-Open No. 2003-065143 (Patent Document 1) has dealt with such a problem, whether a misfire has occurred based on the change pattern of the rotational fluctuation of the internal combustion engine, or the vehicle travels on a rough road. Techniques for determining whether or not are present are disclosed.

Japanese Patent Application Laid-Open No. 2003-065143

  However, for example, when the vehicle is traveling on a road surface where the undulation continuously changes in a predetermined pattern, the change pattern of the rotational fluctuation of the internal combustion engine corresponds to the change pattern of the rotational fluctuation at the time of misfire occurrence. There is a possibility that it becomes a change pattern and misjudged that misfire has occurred.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a vehicle and a misfire determination method for an internal combustion engine that accurately determine whether or not misfire has occurred in the internal combustion engine. .

  A vehicle according to an aspect of the present invention is an internal combustion engine, and whether a misfire has occurred in the internal combustion engine when the rotational fluctuation amount of the internal combustion engine exceeds a misfire determination value, or is the vehicle traveling on a rough road And a control unit for determining. The control unit determines that the vehicle is traveling on a rough road when the rotational fluctuation amount exceeds a rough road determination value that is larger than the misfire determination value.

  Preferably, when the amount of rotational fluctuation is larger than the misfire determination value and smaller than the rough road determination value, the control unit determines that the first change pattern of the rotational fluctuation of the internal combustion engine is the first rotational fluctuation at the time of misfire occurrence. If it corresponds to the two change pattern, it is determined that a misfire has occurred in the internal combustion engine, and if the first change pattern does not correspond to the second change pattern, it is determined that the vehicle is traveling on a rough road.

  More preferably, the internal combustion engine includes a plurality of cylinders. The first change pattern includes the rotation fluctuation amount of each of the first cylinder and the second cylinder different from the first cylinder, in which the rotation fluctuation amount among the plurality of cylinders is larger than the misfire determination value. The second change pattern includes a change pattern in which the rotation fluctuation amount of the second cylinder is within a range set based on the rotation fluctuation amount of the first cylinder when misfire occurs.

  More preferably, the control unit determines at least one of a misfire determination value and a rough road determination value based on the state of the internal combustion engine.

  More preferably, the control unit includes a first rotation time required for the rotation angle of the output shaft of the internal combustion engine to rotate by a predetermined angle, and a second rotation time before one ignition corresponding to the first rotation time. The rotational fluctuation amount is calculated from the difference.

  More preferably, the vehicle further includes a notification unit for notifying the driver of information. The control unit notifies the driver that the misfire has occurred, based on the first number of times that the misfire has occurred and the second number of times that the vehicle has been determined to be traveling on a rough road. Control part.

  A misfire determination method according to another aspect of the present invention is a misfire determination method for an internal combustion engine. The misfire determination method includes a step of determining whether a misfire has occurred in the internal combustion engine when the fluctuation amount of the rotation speed of the internal combustion engine exceeds a misfire determination value, or whether the vehicle is traveling on a rough road, And determining that the vehicle is traveling on a rough road when the fluctuation amount exceeds a rough road determination value that is greater than the misfire determination value.

  According to the present invention, even when the fluctuation amount of the rotational speed of the internal combustion engine is larger than the temporary misfire determination value, if it is larger than the bad road determination value, it is determined that the vehicle is traveling on a bad road, Even when the change pattern of the rotational fluctuation of the internal combustion engine corresponds to the change pattern of the rotational fluctuation at the time of misfiring, it can be determined that the vehicle is traveling on a rough road. Therefore, misjudgment of misfire can be prevented. Therefore, it is possible to provide a vehicle and a misfire determination method for an internal combustion engine that accurately determine whether or not misfire has occurred in the internal combustion engine.

1 is an overall block diagram of a vehicle according to an embodiment. It is a figure which shows the structure of the internal combustion engine mounted in the vehicle which concerns on this Embodiment. It is a functional block diagram of ECU mounted in the vehicle which concerns on this Embodiment. FIG. 6 is a diagram (No. 1) showing a change pattern of rotation fluctuations of the internal combustion engine. It is a flowchart which shows the control structure of the program performed with ECU mounted in the vehicle which concerns on this Embodiment. FIG. 6 is a diagram (No. 2) showing a change pattern of rotation fluctuations of the internal combustion engine.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

  With reference to FIG. 1, an overall block diagram of a vehicle 1 according to the present embodiment will be described. The vehicle 1 includes an engine 10, a drive shaft 16, a first motor generator (hereinafter referred to as a first MG) 20, a second motor generator (hereinafter referred to as a second MG) 30, and a power split device 40. , A reduction gear 58, a PCU (Power Control Unit) 60, a battery 70, a drive wheel 80, a start switch 150, and an ECU (Electronic Control Unit) 200.

  The vehicle 1 travels with driving force output from at least one of the engine 10 and the second MG 30. The power generated by the engine 10 is divided into two paths by the power split device 40. One of the two routes is a route transmitted to the drive wheel 80 via the speed reducer 58, and the other route is a route transmitted to the first MG 20.

  First MG 20 and second MG 30 are, for example, three-phase AC rotating electric machines. First MG 20 and second MG 30 are driven by PCU 60.

  The first MG 20 has a function as a generator that generates power using the power of the engine 10 divided by the power split device 40 and charges the battery 70 via the PCU 60. Further, first MG 20 receives electric power from battery 70 and rotates a crankshaft that is an output shaft of engine 10. Thus, the first MG 20 has a function as a starter for starting the engine 10.

  Second MG 30 has a function as a driving motor that applies driving force to driving wheels 80 using at least one of the electric power stored in battery 70 and the electric power generated by first MG 20. Second MG 30 also has a function as a generator for charging battery 70 via PCU 60 using electric power generated by regenerative braking.

  The engine 10 is, for example, an internal combustion engine such as a gasoline engine or a diesel engine. As shown in FIG. 2, the engine 10 includes an air cleaner 102, a throttle valve 104, a plurality of cylinders 106, an injector 108 that supplies fuel to each of the plurality of cylinders 106, a spark plug 110, and a three-way catalyst 112. A piston 114, a crankshaft 116, an intake valve 118, an exhaust valve 120, an intake side cam 122, an exhaust side cam 124, and a VVT (Variable Valve Timing) mechanism 126.

  Air is drawn into the engine 10 from the air cleaner 102. The intake air amount is adjusted by the throttle valve 104. The throttle valve 104 is an electronic throttle valve that is driven by a motor.

  Air is mixed with fuel in the cylinder 106 (combustion chamber). Fuel is directly injected into the cylinder 106 from the injector 108. That is, the injection hole of the injector 108 is provided in the cylinder 106. The fuel is injected from the intake side (the side where air is introduced) of the cylinder 106.

  Fuel is injected during the intake stroke. Note that the timing of fuel injection is not limited to the intake stroke. In the present embodiment, the engine 10 will be described as a direct injection engine in which the injection hole of the injector 108 is provided in the cylinder 106. However, in addition to the direct injection injector 108, a port injection injector is provided. May be. Further, only a port injection injector may be provided.

  The air-fuel mixture in the cylinder 106 is ignited by the spark plug 110 and burned. The air-fuel mixture after combustion, that is, the exhaust gas is purified by the three-way catalyst 112 and then discharged outside the vehicle. The piston 114 is pushed down by the combustion of the air-fuel mixture, and the crankshaft 116 rotates.

  An intake valve 118 and an exhaust valve 120 are provided at the top of the cylinder 106. The amount and timing of air introduced into the cylinder 106 are controlled by the intake valve 118. The amount and timing of exhaust gas discharged from the cylinder 106 is controlled by the exhaust valve 120. The intake valve 118 is driven by the intake side cam 122. The exhaust valve 120 is driven by the exhaust side cam 124.

  The intake valve 118 is changed in opening / closing timing (phase) by the VVT mechanism 126. The opening / closing timing of the exhaust valve 120 may be changed.

  In the present embodiment, the opening / closing timing of the intake valve 118 is controlled by rotating a camshaft (not shown) provided with the intake side cam 122 by the VVT mechanism 126. The method for controlling the opening / closing timing is not limited to this. In the present embodiment, VVT mechanism 126 is operated by hydraulic pressure. The VVT mechanism 126 may be provided on the exhaust side cam 124.

  The engine 10 is controlled based on a control signal S1 from the ECU 200. The ECU 200 controls the throttle opening, the ignition timing, the fuel injection timing, the fuel injection amount, and the opening / closing timing of the intake valve 118 so that the engine 10 is in a desired operation state. ECU 200 receives signals from crank angle sensor 11, cam angle sensor 204, water temperature sensor 206, and air flow meter 208.

  The crank angle sensor 11 outputs a signal representing the rotational speed of the crankshaft 116 (hereinafter referred to as engine speed) NE and the rotational angle of the crankshaft 116. The cam angle sensor 204 outputs a signal indicating the position of the intake side cam 122. The water temperature sensor 206 outputs a signal indicating the temperature of the cooling water of the engine 10 (hereinafter also referred to as water temperature). The air flow meter 208 outputs a signal representing the amount of air taken into the engine 10.

  The ECU 200 controls the engine 10 based on signals input from these sensors, a map and a program stored in a ROM (Read Only Memory) 202.

  Returning to FIG. 1, power split device 40 mechanically connects each of the three elements of drive shaft 16 for rotating drive wheel 80, the output shaft of engine 10, and the rotation shaft of first MG 20. The power split device 40 enables transmission of power between the other two elements by using any one of the three elements described above as a reaction force element. The rotation shaft of second MG 30 is connected to drive shaft 16.

  Power split device 40 is a planetary gear mechanism including sun gear 50, pinion gear 52, carrier 54, and ring gear 56. Pinion gear 52 meshes with each of sun gear 50 and ring gear 56. The carrier 54 supports the pinion gear 52 so as to be capable of rotating, and is connected to the crankshaft of the engine 10. Sun gear 50 is coupled to the rotation shaft of first MG 20. Ring gear 56 is coupled to the rotation shaft of second MG 30 and reduction gear 58 via drive shaft 16.

  Reducer 58 transmits the power from power split device 40 and second MG 30 to drive wheels 80. Reducer 58 transmits the reaction force from the road surface received by drive wheels 80 to power split device 40 and second MG 30.

  PCU 60 converts the DC power stored in battery 70 into AC power for driving first MG 20 and second MG 30. PCU 60 includes a converter and an inverter (both not shown) controlled based on control signal S2 from ECU 200. The converter boosts the voltage of the DC power received from battery 70 and outputs it to the inverter. The inverter converts the DC power output from the converter into AC power and outputs the AC power to first MG 20 and / or second MG 30. Thus, first MG 20 and / or second MG 30 are driven using the electric power stored in battery 70. The inverter converts AC power generated by the first MG 20 and / or the second MG 30 into DC power and outputs the DC power to the converter. The converter steps down the voltage of the DC power output from the inverter and outputs the voltage to battery 70. Thereby, battery 70 is charged using the electric power generated by first MG 20 and / or second MG 30. The converter may be omitted.

  The battery 70 is a power storage device and is a rechargeable DC power source. As the battery 70, for example, a secondary battery such as nickel metal hydride or lithium ion is used. The voltage of the battery 70 is about 200V, for example. Battery 70 may be charged using electric power supplied from an external power source (not shown) in addition to being charged using electric power generated by first MG 20 and / or second MG 30 as described above. The battery 70 is not limited to a secondary battery, but may be a battery capable of generating a DC voltage, such as a capacitor, a solar battery, or a fuel battery.

  The battery 70 includes a battery temperature sensor 156 for detecting the battery temperature TB of the battery 70, a current sensor 158 for detecting the current IB of the battery 70, and a voltage sensor 160 for detecting the voltage VB of the battery 70. And are provided.

  Battery temperature sensor 156 transmits a signal indicating battery temperature TB to ECU 200. Current sensor 158 transmits a signal indicating current IB to ECU 200. Voltage sensor 160 transmits a signal indicating voltage VB to ECU 200.

  The start switch 150 is, for example, a push switch. The start switch 150 may be configured to insert a key into a key cylinder and rotate it to a predetermined position. Start switch 150 is connected to ECU 200. In response to the driver operating the start switch 150, the start switch 150 transmits a signal ST to the ECU 200.

  The notification unit 152 notifies the driver of the occurrence of misfire. The notification unit 152 is, for example, a warning lamp that notifies the occurrence of misfire by turning on or blinking a mark provided on the meter. Note that the notification unit 152 may be a display device (for example, a liquid crystal panel or the like) for displaying information indicating that a misfire has occurred. Alternatively, the notification unit 152 is a sound generation device for notifying the occurrence of misfire by generating a sound indicating that a misfire has occurred, or notifying that the misfire has occurred by voice. Also good. The notification unit 152 is controlled based on a control signal S3 from the ECU 200.

  The ECU 200 is connected to the first resolver 12, the second resolver 13, and the wheel speed sensor 14.

  The first resolver 12 is provided in the first MG 20, and detects the rotational speed Nm1 of the first MG 20. The first resolver 12 transmits a signal indicating the detected rotation speed Nm1 to the ECU 200.

  The second resolver 13 is provided in the second MG 30 and detects the rotational speed Nm2 of the second MG 30. The second resolver 13 transmits a signal indicating the detected rotation speed Nm2 to the ECU 200.

  The wheel speed sensor 14 detects the rotational speed Nw of the drive wheel 80. The wheel speed sensor 14 transmits a signal indicating the detected rotation speed Nw to the ECU 200. ECU 200 calculates vehicle speed V based on the received rotational speed Nw. ECU 200 may calculate vehicle speed V based on rotation speed Nm2 of second MG 30 instead of rotation speed Nw.

  ECU 200 generates a control signal S1 for controlling engine 10, and outputs the generated control signal S1 to engine 10. ECU 200 also generates a control signal S2 for controlling PCU 60 and outputs the generated control signal S2 to PCU 60.

  The ECU 200 controls the entire hybrid system, that is, the charging / discharging state of the battery 70 and the operating states of the engine 10, the first MG 20 and the second MG 30 so that the vehicle 1 can operate most efficiently by controlling the engine 10, the PCU 60, and the like. .

  ECU 200 calculates a required driving force corresponding to the amount of depression of an accelerator pedal (not shown) provided in the driver's seat. ECU 200 controls the torque of first MG 20 and second MG 30 and the output of engine 10 in accordance with the calculated required driving force.

  In the vehicle 1 having the above configuration, the ECU 200 determines whether or not misfire has occurred in the engine 10 based on the rotation fluctuation amount of the engine 10. However, for example, when the vehicle 1 is traveling on a rough road, the change pattern of the rotation fluctuation of the engine 10 becomes a change pattern corresponding to the change pattern of the rotation fluctuation at the time of misfire, and misfire has occurred. May be misjudged.

  In the present embodiment, ECU 200 determines whether a misfire has occurred in engine 10 or whether the vehicle is traveling on a rough road when the rotational fluctuation amount of engine 10 exceeds the misfire determination value. ECU 200 determines that vehicle 1 is traveling on a rough road when the amount of rotational fluctuation of engine 10 exceeds a rough road determination value that is greater than the misfire determination value. In the present embodiment, the rough road includes a road surface whose undulation continuously changes in a predetermined pattern and a road surface with a low friction coefficient such as a wet road surface, a frozen road surface, or a gravel road.

  FIG. 3 shows a functional block diagram of ECU 200 mounted on vehicle 1 according to the present embodiment. The ECU 200 includes a start determination unit 250, a fluctuation amount calculation unit 252, a temporary misfire determination unit 254, a rough road determination unit 256, a misfire determination unit 258, a notification control unit 260, an end condition determination unit 262, and a counter. And a clear unit 264.

  The start determination unit 250 determines whether a misfire determination start condition is satisfied. The misfire determination start condition is a condition for determining that the state of the engine 10 is a state suitable for misfire determination (determinable with appropriate accuracy). The misfire determination start condition is, for example, a condition that the current engine speed Ne and the engine load factor (or intake air amount) are within a preset region. For example, a region in which the lower limit value of the engine load factor increases as the engine speed Ne increases is set as the region set in advance. The preset area may be adapted by experiments or the like.

  The start determination unit 250 determines that the misfire determination start condition is satisfied, for example, when the current engine speed Ne and the engine load factor are within a preset region. For example, when it is determined that the misfire determination start condition is satisfied, the start determination unit 250 may turn on the start determination flag.

  The fluctuation amount calculation unit 252 calculates the rotation fluctuation amount ΔNe of the engine speed Ne. Specifically, the fluctuation amount calculation unit 252 measures, for example, the time during which the rotation angle of the crankshaft 116 detected by the crank angle sensor 11 changes by a predetermined angle. In the present embodiment, the predetermined angle is, for example, 30 ° CA (Crank Angle). In the following description, the time required for the crankshaft 116 to rotate 30 ° CA is described as T30.

  The fluctuation amount calculation unit 252 is, for example, a first rotation time T30 (required for rotation by 30 ° CA starting from a predetermined angle based on TDC (Top Dead Center) or BDC (Bottom Dead Center) of each cylinder. 1) is measured. In the present embodiment, the predetermined angle refers to a position rotated by 60 ° CA from the rotation angle corresponding to the TDC of each cylinder, but is not particularly limited thereto.

  The fluctuation amount calculation unit 252 calculates the difference (T30 (1) −T30) between the first rotation time T30 (1) and the second rotation time T30 (2) before one ignition corresponding to the first rotation time T30 (1). (2)) is calculated as the rotational fluctuation amount ΔNe of the engine 10.

  For example, it is assumed that the engine 10 is an in-line 4-cylinder engine in which four cylinders from the first cylinder to the fourth cylinder are arranged in series. Further, it is assumed that the engine 10 is subjected to ignition control in the order of the first cylinder, the third cylinder, the fourth cylinder, and the second cylinder.

  For example, when the first rotation time T30 (1) of the third cylinder is measured, the fluctuation amount calculation unit 252 determines the first rotation time T (30) and the first cylinder that is the cylinder before one ignition. A difference (T30 (1) −T30 (2)) from the second rotation time T30 (2) is calculated as the rotation fluctuation amount ΔNe.

  Note that the fluctuation amount calculation unit 252 may start calculating the rotation fluctuation amount ΔNe when the start determination flag is in the on state.

  The provisional misfire determination unit 254 determines whether or not the rotation variation amount ΔNe of the engine 10 calculated by the variation amount calculation unit 252 is greater than or equal to the provisional misfire determination value A (0). In the present embodiment, the provisional misfire determination value A (0) is described as being determined based on the engine speed Ne and the intake air amount, but may be a predetermined value.

  For example, the temporary misfire determination value A (0) may be increased as the engine speed Ne is increased. Alternatively, the provisional misfire determination value A (0) may be decreased as the intake air amount increases.

  Temporary misfire determination unit 254 may turn on the temporary misfire determination flag when, for example, rotation fluctuation amount ΔNe of engine 10 is equal to or greater than temporary misfire determination value A (0).

  The rough road determination unit 256 determines whether or not the vehicle 1 is traveling on a rough road. Specifically, the rough road determination unit 256 determines whether or not the rotational fluctuation amount ΔNe of the engine 10 calculated by the fluctuation amount calculation unit 252 is larger than the rough road determination value A (1). The rough road determination value A (1) is a value larger than the temporary misfire determination value A (0). In the present embodiment, the rough road determination value A (1) is described as being determined based on the engine speed Ne and the intake air intake amount, but may be a predetermined value.

  For example, the rough road determination value A (1) may increase as the engine speed Ne increases. Alternatively, the rough road determination value A (1) may be decreased as the intake air amount increases.

  When the rough road determination unit 256 determines that the vehicle 1 is traveling on a rough road (that is, when it is determined that the rotational fluctuation amount ΔNe of the engine 10 is equal to or greater than the rough road determination value A (1)). ) Increase the value of the rough road counter by a predetermined value (for example, “1”).

  The misfire determination unit 258 determines whether or not misfire has occurred in the engine 10. More specifically, the temporary misfire determination unit 254 determines that the rotational fluctuation amount ΔNe of the engine 10 is greater than or equal to the temporary misfire determination value A (0), and the rough road determination unit 256 determines the rotational fluctuation amount ΔNe of the engine 10. Is determined to be smaller than the rough road determination value A (1), it is determined whether or not the first change pattern of the rotational fluctuation of the engine 10 corresponds to the second change pattern of the rotational fluctuation at the time of misfire occurrence. .

  When it is determined that the first change pattern corresponds to the second change pattern, the misfire determination unit 258 determines that a misfire has occurred in the engine 10. When it is determined that misfire has occurred in the engine 10, the misfire determination unit 258 increases the misfire counter by a predetermined value (for example, “1”).

  In the present embodiment, the misfire counter is described as indicating the total number of misfires that have occurred in all cylinders. However, if the cylinder in which the misfire has occurred can be specified, it is provided for each cylinder. Also good.

  The misfire determination unit 258 determines that the vehicle 1 is traveling on a bad road when it is determined that the first change pattern does not correspond to the second change pattern. If the misfire determination unit 258 determines that the vehicle 1 is traveling on a rough road, the misfire determination unit 258 increases the rough road counter by a predetermined value.

  The first change pattern includes the rotation fluctuation amount ΔNe of each of the first cylinder and the second cylinder different from the first cylinder in which the rotation fluctuation amount ΔNe among the plurality of cylinders is equal to or greater than the provisional misfire determination value A (0). Further, the second change pattern includes a change pattern in which the rotation fluctuation amount of the second cylinder is within a range set based on the rotation fluctuation amount ΔNe of the first cylinder when misfire occurs.

  In the present embodiment, as shown in FIG. 3, the first change pattern includes the rotational fluctuation amount ΔNe (2) of the third cylinder determined to be larger than the temporary misfire determination value A (0) and the third change pattern. The rotational fluctuation amount ΔNe (3) of the first cylinder, which is the cylinder before the first ignition of the cylinder, the rotational fluctuation amount ΔNe (1) of the fourth cylinder, which is the cylinder after the first ignition of the third cylinder, and the third cylinder 2 and the rotational fluctuation amount ΔNe (0) of the second cylinder, which is the cylinder after ignition.

  The misfire determination unit 258 determines whether or not the first change pattern including ΔNe (0), ΔNe (1), ΔNe (2), and ΔNe (3) corresponds to the second change pattern at the time of misfire occurrence.

  Specifically, the misfire determination unit 258 determines whether or not the following determination condition is satisfied. The determination conditions are: ΔNe (0) <0, A ≦ | ΔNe (0) / ΔNe (2) | ≦ B, −C ≦ ΔNe (3) / ΔNe (2) ≦ + C, −D ≦ ΔNe (1) / This is a condition that the relationship ΔNe (2) ≦ + D is established. A, B, C, and D are values larger than zero.

  When these relationships are established, it indicates that each of ΔNe (0), ΔNe (1), and ΔNe (3) is a value within a predetermined range based on ΔNe (2).

  In the misfire determination unit 258, for example, as shown in FIG. 4, each of ΔNe (0), ΔNe (1), and ΔNe (3) is within a range between the upper limit value and the lower limit value based on the above-described relationship. In the case, it is determined that the first change pattern corresponds to the second change pattern. That is, misfire determination unit 258 determines that misfire has occurred in engine 10.

  On the other hand, when one of ΔNe (0), ΔNe (1), and ΔNe (3) is a value exceeding the upper limit value or the lower limit value shown in FIG. It is determined that the pattern does not correspond to the second change pattern. That is, the misfire determination unit 258 determines that the vehicle 1 is traveling on a rough road.

  The notification control unit 260 determines whether or not it is necessary to notify the driver that a misfire has occurred in the engine 10 based on the misfire counter and the rough road counter. When it is determined that notification is required, the notification control unit 260 controls the notification unit 152 to notify the driver of the occurrence of misfire. For example, the notification control unit 260 may determine that notification is required when a value obtained by subtracting a value obtained by multiplying the value of the rough road counter by a predetermined coefficient from the value of the misfire counter is equal to or greater than a predetermined value. Alternatively, the notification control unit 260 may determine that notification is required regardless of the value of the rough road counter when the value of the misfire counter is equal to or greater than a predetermined value.

  The termination condition determination unit 262 determines whether a termination condition for the misfire determination is satisfied. The end condition is, for example, a condition that the crankshaft 116 of the engine 10 has been rotated a predetermined number of times after the misfire determination start condition is satisfied. Note that the end condition determination unit 262 may turn on the end determination flag when, for example, an end condition for misfire determination is satisfied.

  The counter clear unit 264 clears the rough road counter and the misfire counter and resets them to initial values (for example, “0”) when the end condition determination unit 262 determines that the end condition of the misfire determination is satisfied. . Note that the counter clear unit 264 may clear the rough road counter and the misfire counter when the end determination flag is turned on from off, for example.

  In the present embodiment, a start determination unit 250, a fluctuation amount calculation unit 252, a temporary misfire determination unit 254, a rough road determination unit 256, a misfire determination unit 258, a notification control unit 260, and an end condition determination unit 262. The counter clear unit 264 is described as functioning as software that is realized when the CPU of the ECU 200 executes a program stored in the ROM 202, but may be realized as hardware. Good. Such a program is recorded on a storage medium and mounted on the vehicle.

  With reference to FIG. 5, a control structure of a program executed by ECU 200 mounted on vehicle 1 according to the present embodiment will be described. ECU 200 executes a program based on the flowchart shown in FIG. 5 every predetermined calculation cycle.

  In step (hereinafter, step is referred to as S) 100, ECU 200 determines whether or not a misfire determination start condition is satisfied. If the misfire determination start condition is satisfied (YES in S100), the process proceeds to S102. If not (NO in S100), the process returns to S100.

  In S102, ECU 200 calculates rotation fluctuation amount ΔNe of engine 10. Since the calculation method of the rotation fluctuation amount ΔNe is as described above, the detailed description thereof will not be repeated.

  In S104, ECU 200 determines whether or not rotation variation amount ΔNe of engine 10 is equal to or greater than temporary misfire determination value A (0). If rotational fluctuation amount ΔNe of engine 10 is greater than or equal to provisional misfire determination value A (0) (YES in S104), the process proceeds to S106. If not (NO in S104), the process proceeds to S108.

  In S106, ECU 200 determines whether or not rotation fluctuation amount ΔNe of engine 10 is equal to or greater than the rough road determination value A (1). If rotational fluctuation amount ΔNe of engine 10 is greater than or equal to rough road determination value A (1) (YES in S106), the process proceeds to S108. If not (NO in S106), the process proceeds to S110.

  In S108, ECU 200 adds a predetermined value to the rough road counter to increase it. In S110, ECU 200 determines whether or not the first change pattern of the rotation fluctuation of engine 10 corresponds to the second change pattern of the rotation fluctuation when misfire occurs. If the first change pattern of the rotational fluctuation of engine 10 corresponds to the second change pattern of the rotational fluctuation at the time of misfire occurrence (YES in S110), the process proceeds to S112. If not (NO in S110), the process proceeds to S108.

  In S112, ECU 200 increases the misfire counter by adding a predetermined value. In S1114, ECU 200 determines whether or not a notification that misfire has occurred in engine 10 is required based on the value of the misfire counter and the value of the rough road counter. If it is determined that notification is required (YES in S114), the process proceeds to S116. If not (NO in S114), the process proceeds to S118. In S116, ECU 200 controls notification unit 152 to notify the driver that a misfire has occurred. ECU 200 turns on a warning lamp indicating the occurrence of misfire, for example.

  In S118, ECU 200 determines whether or not crankshaft 116 of engine 10 has rotated a predetermined number of revolutions since the start condition is satisfied. If it has rotated by a predetermined number of revolutions (YES in S118), the process proceeds to S120. If not (NO in S118), the process returns to S102. In S120, ECU 200 clears the value of the rough road counter and the value of the misfire counter.

  An operation of ECU 200 mounted on vehicle 1 according to the present embodiment based on the above-described structure and flowchart will be described.

  For example, if the engine speed Ne and the engine load factor are within a preset region while the vehicle 1 is traveling, it is determined that the misfire determination start condition is satisfied (YES in S100), and the engine A rotational fluctuation amount ΔNe of 10 is calculated (S102).

  If calculated rotation fluctuation amount ΔNe is smaller than provisional misfire determination value A (0) (NO in S104), if the misfire determination start condition is satisfied and the vehicle has rotated by a predetermined number of rotations (in S118). YES), the misfire counter and the rough road counter are cleared (S120). If the engine has not been rotated by the predetermined number of revolutions (NO in S118), the calculation of the rotation fluctuation amount ΔNe of engine 10 is continued (S102).

  As shown by the thick broken line in FIG. 6, for example, the rotational fluctuation amount ΔNe (2) in the third cylinder is equal to or greater than the provisional misfire determination value A (0) (YES in S104), and the rough road determination value A If (1) or more (YES in S106), the value of the rough road counter is increased by a predetermined value (S108).

  On the other hand, as shown by the thick solid line in FIG. 6, for example, the rotational fluctuation amount ΔNe (2) in the third cylinder is equal to or greater than the temporary misfire determination value A (0) (YES in S104), and the bad road determination is made. If smaller than value A (1) (NO in S106), it is determined whether or not the first change pattern of the rotational fluctuation of engine 10 corresponds to the second change pattern at the time of misfire occurrence (S110). .

  That is, when the rotational fluctuation amounts ΔNe (0), ΔNe (1), and ΔNe (3) at the time of ignition of each cylinder other than the third cylinder are within a predetermined range based on ΔNe (2), the engine 10 It is determined that the first change pattern of the rotational fluctuation corresponds to the second change pattern at the time of misfire (YES in S110). In this case, the value of the misfire counter is increased (S112), and it is determined whether or not misfire has occurred (S114). If it is determined that a notification that a misfire has occurred is required based on the value of the misfire counter and the value of the rough road counter (YES in S114), notification control is executed (S116).

  On the other hand, as shown by the one-dot chain line in FIG. 6, when the rotational fluctuation amount ΔNe (1) in the fourth cylinder is not within the predetermined range, the first change pattern of the rotational fluctuation of the engine 10 is the second change when a misfire occurs. It is determined that the pattern does not correspond (NO in S110), and the value of the rough road counter is increased (S108).

  If the predetermined rotation has been made after the misfire determination start condition is satisfied (YES in S118), the misfire counter value and the bad road counter value are cleared (S120).

  As described above, according to the vehicle according to the present embodiment, even when rotational fluctuation amount ΔNe of engine 10 is larger than provisional misfire determination value A (0), it is larger than rough road determination value A (1). It is determined that the vehicle 1 is traveling on a rough road. Thereby, even when the first change pattern of the rotational fluctuation of the engine 10 corresponds to the second change pattern of the rotational fluctuation at the time of misfire occurrence, it can be determined that the vehicle 1 is traveling on a rough road. Therefore, misjudgment of misfire can be prevented. Therefore, it is possible to provide a vehicle and a misfire determination method for an internal combustion engine that accurately determine whether or not misfire has occurred in the internal combustion engine.

  In the present embodiment, it has been described that the driver is notified when it is determined that a misfire has occurred based on the value of the misfire counter and the value of the rough road counter. If misfires occur continuously at, fuel injection of the specific cylinder may be stopped.

  In the present embodiment, the vehicle 1 has been described as being a hybrid vehicle. However, the vehicle 1 is not particularly limited to a hybrid vehicle as long as it is a vehicle that is linked to at least the rotational fluctuation of the driving wheel and the rotational fluctuation of the engine. . For example, the vehicle 1 may be a vehicle in which drive wheels are mechanically coupled. That is, the vehicle 1 may be a vehicle that uses only the engine 10 as a drive source, for example.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  1 vehicle, 10 engine, 11 crank angle sensor, 12, 13 resolver, 14 wheel speed sensor, 16 drive shaft, 20, 30 MG, 40 power split device, 50 sun gear, 52 pinion gear, 54 carrier, 56 ring gear, 58 reducer , 60 PCU, 70 battery, 80 driving wheel, 102 air cleaner, 104 throttle valve, 106 cylinder, 108 injector, 110 spark plug, 112 three way catalyst, 114 piston, 116 crankshaft, 118 intake valve, 120 exhaust valve, 122 intake Side cam, 124 exhaust side cam, 126 VVT mechanism, 150 start switch, 152 notification unit, 156 battery temperature sensor, 158 current sensor, 160 voltage sensor, 200 ECU, 202 ROM, 204 cam angle sensor 206 water temperature sensor, 208 air flow meter, 250 start determination unit, 252 fluctuation amount calculation unit, 254 temporary misfire determination unit, 256 rough road determination unit, 258 misfire determination unit, 260 notification control unit, 262 end condition determination unit, 264 counter clear Department.

Claims (6)

An internal combustion engine;
A control unit for determining whether a misfire has occurred in the internal combustion engine when the rotational fluctuation amount of the internal combustion engine exceeds a misfire determination value, or whether the vehicle is traveling on a rough road,
The control unit is
When the rotational fluctuation amount exceeds a rough road determination value larger than the misfire determination value, it is determined that the vehicle is traveling on the rough road ,
When the rotational fluctuation amount is larger than the misfire determination value and smaller than the rough road determination value, the first change pattern of the rotational fluctuation of the internal combustion engine is the second change of the rotational fluctuation when a misfire occurs. If it corresponds to a pattern, it is determined that the misfire has occurred in the internal combustion engine, and if the first change pattern does not correspond to the second change pattern, the vehicle is traveling on the rough road. It is determined that the vehicle. The internal combustion engine includes a plurality of cylinders,
The first change pattern includes the rotation fluctuation amount of each of a first cylinder and a second cylinder different from the first cylinder, wherein the rotation fluctuation amount of the plurality of cylinders is larger than the misfire determination value.
The second change pattern, the rotation fluctuation amount of the second cylinder during the misfire comprises a change pattern falls within a range which is set the rotational fluctuation amount of the first cylinder as a reference, in claim 1 The vehicle described. The control unit determines at least either one of the misfire judgment value and the bad road determination value based on the state of the internal combustion engine, the vehicle according to claim 1 or 2. The control unit includes a difference between a first rotation time required for the rotation angle of the output shaft of the internal combustion engine to rotate by a predetermined angle and a second rotation time before one ignition corresponding to the first rotation time. It calculates the revolution speed fluctuation amount from the vehicle according to any one of claims 1-3. The vehicle further includes a notification unit for notifying the driver of information,
The control unit determines that the misfire has occurred based on a first number of times that the misfire has occurred and a second number of times that the vehicle has determined that the vehicle is traveling on the rough road. It controls the notification unit to notify the vehicle according to any one of claims 1-4. A misfire determination method for an internal combustion engine,
Determining whether a misfire has occurred in the internal combustion engine when the amount of change in the rotational speed of the internal combustion engine exceeds a misfire determination value, or whether the vehicle is traveling on a rough road;
A step of determining that the vehicle is traveling on the rough road when the fluctuation amount exceeds a rough road determination value greater than the misfire determination value ;
When the fluctuation amount is larger than the misfire determination value and smaller than the rough road determination value, the first change pattern of the rotation fluctuation of the internal combustion engine is the second change pattern of the rotation fluctuation when the misfire occurs. Is determined that the misfire has occurred in the internal combustion engine, and the vehicle is traveling on the rough road if the first change pattern does not correspond to the second change pattern. A misfire determination method for an internal combustion engine, comprising: a determination step .

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