JP2009126272A - Power output unit of vehicle and its control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power output unit of a vehicle which prevents excess rotation of a driving system upon sharp change of rotation of a wheel and to provide its control method. <P>SOLUTION: The power output unit includes a motor generator MG 1, an engine 22 and a power dividing mechanism 30 to which a drive shaft which drives a wheel is combined. An HV-ECU 70 performs torque reduction control to reduce generation of torque of the engine 22 when the number of rotation of the drive shaft changes in the reduction direction exceeding a threshold. The torque reduction control includes a process to correct ignition timing so as to reduce generation of torque and a process to suspend fuel supply to an internal combustion engine. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a vehicle power output device and a control method thereof, and more particularly to a vehicle power output device including an internal combustion engine and a rotating electric machine.

  A hybrid vehicle having an engine and a rotating electric machine as drive sources is known. In such a hybrid vehicle, an engine and a rotating electric machine are selectively used according to the traveling state of the vehicle. For example, the vehicle travels mainly using an engine when traveling at a high speed, and travels mainly using a rotating electrical machine when traveling at a medium or low speed. One such hybrid vehicle is equipped with a differential mechanism having a rotating element connected to a rotating electrical machine and a rotating element connected to an engine.

  Japanese Patent Application Laid-Open No. 2004-153946 (Patent Document 1) discloses that four elements of a main power source, a first motor (rotary electric machine), a second motor, and an output member are the first motor and main power source on the collinear diagram. A motor over-rotation prevention control device for a hybrid vehicle equipped with a hybrid drive system having a gear mechanism (differential mechanism) connected so as to be in the order of the rotation speed of the output member and the second motor is disclosed. This motor over-rotation prevention control device sets the gear ratio so that the operating point of the main power source is on the optimum energy efficiency line, and the rotational speeds of the first motor and the second motor calculated based on the gear ratio setting. Among these, when the rotational speed of one of the motors is determined to be over-rotation, a motor over-rotation prevention control unit that reduces the rotational speed of the motor by correcting the main power source rotational speed command value is included.

According to the motor overspeed prevention control device described in this publication, when it is determined that the motor rotation speed is excessive, the motor rotation speed is reduced by correcting the main power source rotation speed command value. As a result, when the motor rotation speed is predicted to over-rotate, over-rotation of the motor can be prevented in advance by correcting the rotational speed of the main power source.
JP 2004-153946 A

  In a hybrid vehicle, a planetary gear may be used as such a differential mechanism.

FIG. 7 is an alignment chart of an example using a planetary gear as a differential mechanism.
The relationship between the rotational speed (rotational speed) and torque of the three planetary gear axes (sun gear shaft, ring gear shaft, and planetary carrier) can be expressed as a diagram called a collinear diagram illustrated in FIG. In FIG. 7, the vertical axis represents three rotational speed axes, and Ns, Nc, and Nr represent the rotational speeds of the sun gear shaft, the planetary carrier, and the ring gear shaft. The horizontal axis in FIG. 7 represents the ratio of the positions of the three coordinate axes. That is, when the positions of the sun gear shaft and the ring gear shaft are taken at both ends, the coordinate axis of the planetary carrier is determined at a position that internally divides both ends into 1: ρ. Here, ρ is the ratio of the number of teeth of the sun gear to the number of teeth of the ring gear, and is expressed by the following equation (1).
ρ = (number of teeth of sun gear) / (number of teeth of ring gear) (1)
In the example of FIG. 7, the sun gear of the planetary gear is connected to the rotating shaft of the first rotating electrical machine, the carrier is connected to the rotating shaft of the engine, and the ring gear drives the wheel that is linked to the rotating shaft of the second rotating electrical machine. Connected to a drive shaft. Therefore, the relationship of Ns = Nm1, Nc = Ne, Nr∝Nm2 holds.

The rotational speed Ne of the engine can be plotted on the coordinate axis of the planetary carrier to which the crankshaft of the engine is coupled, and the rotational speed of the wheel drive shaft (a value proportional to Nm2) can be plotted on the coordinate axis of the ring gear shaft. If a straight line passing through these two points is drawn, the rotational speed Nm1 of the first rotating electrical machine can be obtained as the rotational speed represented by the intersection of the straight line and the coordinate axis of the sun gear. Hereinafter, this straight line is called an operation collinear line. In addition, the relationship of the following proportional calculation formula (following Formula (2)) is materialized in rotation speed Ns, Nc, Nr. As described above, in the planetary gear, when any two rotations of the sun gear shaft, the ring gear shaft, and the planetary carrier are determined, the remaining one rotation is determined based on the determined two rotations.
Ns = Nr− (Nr−Nc) · (1 + ρ) / ρ (2)
Such a relationship can visually represent a change in the number of rotations by using the alignment chart of FIG.

  In the following, consider the case where the wheel is locked during the period from the start of braking to the complete stop of the wheel during traveling.

FIG. 8 is a diagram for explaining a change in the number of rotations when the wheel is locked.
As indicated by an arrow A1 in FIG. 8, when the wheel is locked at the start of braking, the rotational speed of the ring gear shaft is abruptly reduced.

  At this time, the carrier to which the operating engine is connected has a large inertial force because the engine continues to produce torque, and cannot change so rapidly as indicated by an arrow A2. Therefore, it acts as a lever for the operation collinear lever, and the rotational speed Nm1 of the sun gear shaft increases rapidly as indicated by an arrow A3. As a result, the rotation of the first rotating electrical machine exceeds the system upper limit number of rotations Nm1max, resulting in excessive rotation. Further, the planetary pinion gear rotation speed is proportional to the rotation speed difference between the carrier shaft and the ring shaft.

  Accordingly, it is desirable to prevent the sun gear shaft from over-rotating by quickly reducing the engine speed when the wheel is locked.

  An object of the present invention is to provide a power output apparatus for a vehicle and a control method therefor, in which an over-rotation of a drive system is prevented at the time when a wheel rotation suddenly changes.

  In summary, the present invention provides a power output apparatus for a vehicle, comprising: an internal combustion engine, a first rotating electrical machine, wheels, a first rotating element that is linked to a rotating shaft of the first rotating electrical machine, and an internal combustion engine. A power split mechanism having a second rotating element interlocked with the rotating shaft and a third rotating element interlocked with a drive shaft for driving the wheel, and a control unit for controlling the internal combustion engine and the first rotating electrical machine. When the rotational speed of the drive shaft changes in a decreasing direction exceeding the threshold value, the control unit executes torque reduction control for reducing the generated torque of the internal combustion engine. The torque reduction control includes a process of correcting the ignition timing so that the generated torque of the internal combustion engine is reduced, and a process of stopping fuel supply to the internal combustion engine.

  Preferably, the internal combustion engine includes a plurality of cylinders, a plurality of fuel injection valves respectively corresponding to the plurality of cylinders, and a plurality of ignition devices respectively corresponding to the plurality of cylinders. When executing the torque reduction control, the control unit corrects the retard amount of the ignition timing so that the generated torque of the internal combustion engine decreases for the cylinder after the fuel injection and before the ignition, and after the fuel injection and Fuel injection is stopped for the cylinder after ignition.

  More preferably, the control unit determines a correction amount for the retard amount of the ignition timing in accordance with the rotational speed of the internal combustion engine and the load factor of the internal combustion engine.

  Preferably, the power output apparatus for a vehicle further includes a second rotating electric machine having a rotating shaft interlocking with the drive shaft. The control unit executes power running and regeneration control of the first and second rotating electrical machines.

  According to another aspect of the present invention, an internal combustion engine, a first rotating electrical machine, a wheel, a first rotating element interlocked with a rotating shaft of the first rotating electrical machine, and a first rotating element interlocked with a rotating shaft of the internal combustion engine. And a power split device having a third rotating element interlocked with a drive shaft for driving a wheel, wherein the rotational speed of the drive shaft exceeds a threshold value. A step of determining whether or not to change in the decreasing direction, and when the rotational speed of the drive shaft exceeds the threshold, the torque reduction control is performed to reduce the generated torque of the internal combustion engine. Performing. The step of executing the torque reduction control includes the step of correcting the ignition timing so that the torque generated by the internal combustion engine is reduced, and the step of stopping the fuel supply to the internal combustion engine.

  Preferably, the internal combustion engine includes a plurality of cylinders, a plurality of fuel injection valves respectively corresponding to the plurality of cylinders, and a plurality of ignition devices respectively corresponding to the plurality of cylinders. In the step of correcting the ignition timing, when executing the torque reduction control, the retard amount of the ignition timing is corrected so that the generated torque of the internal combustion engine decreases with respect to the cylinder after fuel injection and before ignition. The step of stopping the fuel supply stops the fuel injection to the cylinder after the fuel injection and after the ignition.

  Preferably, in the step of correcting the ignition timing, a correction amount for the retard amount of the ignition timing is determined according to the rotational speed of the internal combustion engine and the load factor of the internal combustion engine.

  According to the present invention, the speed at which the rotation of the engine is reduced is improved, and over-rotation of the drive system when the wheels are locked is prevented.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated.

  FIG. 1 is a schematic diagram of a configuration of a hybrid vehicle 20 equipped with an internal combustion engine as an embodiment of the present invention.

  Referring to FIG. 1, hybrid vehicle 20 includes an engine 22, a three-shaft power split mechanism 30 connected to crankshaft 26 as an output shaft of engine 22 via damper 28, and power split mechanism 30. Motor generator MG1 connected to generate power, reduction gear 35 attached to ring gear shaft 32a as a drive shaft connected to power split mechanism 30, motor generator MG2 connected to reduction gear 35, and power output device A hybrid electronic control unit 70 (hereinafter referred to as HV-ECU 70) for controlling the whole is provided.

  The engine 22 is an internal combustion engine that outputs power using a hydrocarbon-based fuel such as gasoline or light oil, and an engine electronic control unit 24 (hereinafter referred to as an engine ECU 24) that receives signals from various sensors that detect the operating state of the engine 22. The operation control such as the fuel injection control, the ignition control, and the intake air amount adjustment control is performed. The engine ECU 24 communicates with the HV-ECU 70, controls the operation of the engine 22 based on a control signal from the HV-ECU 70, and outputs data related to the operating state of the engine 22 to the HV-ECU 70 as necessary.

  The power split mechanism 30 includes an external gear sun gear 31, an internal gear ring gear 32 arranged concentrically with the sun gear 31, a plurality of pinion gears 33 that mesh with the sun gear 31 and mesh with the ring gear 32, And a carrier 34 for holding the pinion gear 33 so as to rotate and revolve freely. The power split mechanism 30 is configured as a planetary gear mechanism that performs a differential action with the sun gear 31, the ring gear 32, and the carrier 34 as rotational elements.

  Assuming that the rotational speed Ns of the sun gear 31, the rotational speed Nr of the ring gear 32, and the rotational speed Nc of the carrier 34, the relationship of the collinear charts described in FIG. 7 and FIG. The relationship of the above formulas (1) and (2) is also established.

  A crankshaft 26 of the engine 22 is connected to the carrier 34, a motor generator MG1 is connected to the sun gear 31, and a reduction gear 35 is connected to the ring gear 32 via a ring gear shaft 32a. Therefore, assuming that the engine speed Ne, the motor generator MG1 speed Nm1, and the motor generator MG2 speed Nm2, the relationship Ns = Nm1, Nc = Ne, Nr = k · Nm2 holds. Here, k is a reduction ratio of the reduction gear 35.

  When motor generator MG1 functions as a generator, power from engine 22 input from carrier 34 is distributed to sun gear 31 side and ring gear 32 side according to the gear ratio. When motor generator MG1 functions as an electric motor, the power from engine 22 input from carrier 34 and the power from motor generator MG1 input from sun gear 31 are integrated and output to ring gear 32 side. The power output to the ring gear 32 is finally output from the ring gear shaft 32a to the drive wheels 63a and 63b of the vehicle via the gear mechanism 60 and the differential gear 62.

  Motor generator MG1 and motor generator MG2 are both synchronous generator motors that can be driven as generators and motors, and exchange power with battery 50 through inverters 41 and 42.

  The power line 54 connecting the inverters 41 and 42 and the battery 50 includes a positive electrode bus and a negative electrode bus shared by the inverters 41 and 42. As a result, the electric power generated by either motor generator MG1 or MG2 can be consumed by another motor. Therefore, battery 50 is charged / discharged by electric power generated from one of motor generators MG1 and MG2 or insufficient electric power.

  Note that the battery 50 is not charged / discharged if the power balance is balanced by the motor generators MG1, MG2.

  Motor generators MG1, MG2 are both driven and controlled by a motor electronic control unit (hereinafter referred to as motor ECU) 40. The motor ECU 40 includes signals necessary for driving and controlling the motor generators MG1 and MG2, such as signals from rotational position detection sensors 43 and 44 that detect the rotational positions of the rotors of the motor generators MG1 and MG2, and current sensors (not shown). The phase current applied to the motor generators MG1 and MG2 detected by the above is input.

  The motor ECU 40 outputs a switching control signal to the inverters 41 and 42. The motor ECU 40 communicates with the HV-ECU 70, controls the drive of the motor generators MG1 and MG2 by a control signal from the HV-ECU 70, and transmits data related to the operation state of the motor generators MG1 and MG2 to the HV-ECU 70 as necessary. Output.

  The battery 50 is managed by a battery electronic control unit 52 (hereinafter referred to as a battery ECU 52). The battery ECU 52 receives signals necessary for managing the battery 50, for example, a voltage between terminals from a voltage sensor (not shown) installed between terminals of the battery 50, and a power line 54 connected to the output terminal of the battery 50. The charging / discharging current from the attached current sensor (not shown), the battery temperature Tb from the temperature sensor 51 attached to the battery 50, and the like are input, and the HV-ECU 70 communicates data regarding the state of the battery 50 as necessary. Output to. The battery ECU 52 also calculates the remaining capacity (SOC) based on the integrated value of the charge / discharge current detected by the current sensor in order to manage the battery 50.

  The HV-ECU 70 is configured around the CPU 72. In addition to the CPU 72, the HV-ECU 70 includes a ROM 74 that stores processing programs and maps, a RAM 76 that temporarily stores data, and input / output ports and communication ports (not shown).

  The HV-ECU 70 includes an ignition signal from the ignition switch 80, a shift position SP from the shift position sensor 82 that detects the operation position of the shift lever 81, and an accelerator from the accelerator pedal position sensor 84 that detects the amount of depression of the accelerator pedal 83. The opening degree Acc, the brake pedal position BP from the brake pedal position sensor 86 for detecting the depression amount of the brake pedal 85, the vehicle speed V from the vehicle speed sensor 88, and the like are input via the input port.

  As described above, the HV-ECU 70 is connected to the engine ECU 24, the motor ECU 40, and the battery ECU 52 via the communication port, and exchanges various control signals and data with the engine ECU 24, the motor ECU 40, and the battery ECU 52.

  The hybrid vehicle 20 calculates the required torque to be output to the ring gear shaft 32a as the drive shaft based on the accelerator opening Acc and the vehicle speed V corresponding to the depression amount of the accelerator pedal 83 by the driver. The operation of the engine 22, the motor generator MG1, and the motor generator MG2 is controlled so that the required power corresponding to this required torque is output to the ring gear shaft 32a.

  As operation control of the engine 22, the motor generator MG1, and the motor generator MG2, there are a torque conversion operation mode, a charge / discharge operation mode, a motor operation mode, and the like.

  In the torque conversion operation mode, the HV-ECU 70 controls the operation of the engine 22 so that power corresponding to the required power is output from the engine 22, and all of the power output from the engine 22 is transmitted to the power split mechanism 30 and the motor generator. Motor generator MG1 and motor generator MG2 are driven and controlled so that torque is converted by MG1 and motor generator MG2 and output to ring gear shaft 32a.

  In the charge / discharge operation mode, the HV-ECU 70 controls the operation of the engine 22 so that the power corresponding to the sum of the required power and the power required for charging / discharging the battery 50 is output from the engine 22, All or part of the motive power output from the engine 22 with the discharge is output to the ring gear shaft 32a with the torque conversion by the power split mechanism 30, the motor generator MG1, and the motor generator MG2. Motor generator MG1 and motor generator MG2 are driven and controlled.

  In the motor operation mode, the HV-ECU 70 drives and controls the motor generator MG1 and the motor generator MG2 so as to stop the operation of the engine 22 and output power corresponding to the required power from the motor generator MG2 to the ring gear shaft 32a.

  In FIG. 1, the control unit for power output is realized by the HV-ECU 70, the motor ECU 40, the battery ECU 52, and the engine ECU 24. However, these ECUs may be combined into a smaller number of ECUs. You may make it implement | achieve with many ECU of the more fragmented function.

FIG. 2 is a schematic diagram for explaining the periphery of the engine 22 of the vehicle 20.
Referring to FIG. 2, engine 22 includes an intake passage 111 for introducing intake air to the cylinder head and an exhaust passage 113 for exhausting air from the cylinder head.

  An air cleaner 102, an air flow meter 104, an intake air temperature sensor 106, and a throttle valve 107 are provided in this order from the upstream side of the intake passage 111. The opening degree of the throttle valve 107 is controlled by an electronic control throttle 108. An injector 110 that injects fuel is provided near the intake valve of the intake passage 111.

  In the exhaust passage 113, an air-fuel ratio sensor 145, a catalytic device 127, an oxygen sensor 146, and a catalytic device 128 are arranged in this order from the exhaust valve side. The engine 22 further detects a piston 114 that moves up and down a cylinder provided in the cylinder block, a crank position sensor 143 that detects rotation of a crankshaft that rotates in accordance with the up and down movement of the piston 114, and vibrations of the cylinder block. It includes a knock sensor 144 that detects the occurrence of knocking, and a water temperature sensor 148 attached to the cooling water passage of the cylinder block.

  The engine ECU 24 controls the electronic control throttle 108 in accordance with the output of the accelerator pedal position sensor 84 obtained via the HV-ECU of FIG. 1 to change the intake air amount, and the crank angle obtained from the crank position sensor 143 In response to this, an ignition instruction is output to the ignition coil 112 to cause a spark discharge from the spark plug, and the fuel injection timing is output to the injector 110. Further, the fuel injection amount, the air amount, the intake valve opening / closing timing, and the ignition timing are corrected according to the outputs of the intake air temperature sensor 106, knock sensor 144, air-fuel ratio sensor 145, and oxygen sensor 146.

  The vehicle 20 further includes a fuel tank and a fuel pump (not shown). The fuel sucked up from the fuel tank by the fuel pump is pressurized, and when the injector 110 is opened at a predetermined timing, the fuel is sucked into the intake passage 111. It is injected in.

  In the power output apparatus that drives the vehicle using the engine 22 as described in FIG. 2 and the motor generators MG1 and MG2 as shown in FIG. 1, in order to solve the problem of overspeed as described in FIG. It is conceivable that the fuel supply to the engine is stopped when the wheels are locked, and the torque generated in the engine is reduced to rapidly reduce the engine speed.

  However, even if the fuel cut command is issued, if the fuel that has already been injected at the time of detecting the wheel lock is subsequently ignited, torque is generated in the engine, so the engine torque cannot be reduced immediately. Although it is conceivable that the injected fuel is not ignited, unburned fuel is released into the atmosphere, which causes a problem of deterioration in emissions. Therefore, it is preferable to suppress the torque generated in the engine while burning the injected fuel.

  FIG. 3 is a flowchart for illustrating control of the internal combustion engine in the present embodiment. The process of this flowchart is called from the main routine and executed whenever a certain time elapses or a predetermined condition is satisfied.

  Referring to FIG. 3, first, when the process is started, in step S <b> 1, HV-ECU 70 acquires rotational speeds Nm <b> 1 and Nm <b> 2 from rotational position detection sensors 43 and 44 via motor ECU 40. Then, a change amount ΔNm2 is obtained from the difference between the rotation speed Nm2 acquired last time and the rotation speed Nm2 acquired this time, and it is determined whether or not the value is equal to or less than a threshold value Nt2. Further, it is determined whether or not the rotation speed Nm1 acquired this time is equal to or greater than a threshold value Nt1.

  The threshold value Nt2 is a threshold value for determining whether or not the wheel is locked. Since ΔNm2 becomes a negative value when the wheel is locked, the threshold value Nt2 is a negative number.

  Threshold value Nt1 is a threshold value for determining whether motor generator MG1 is over-rotating. Threshold value Nt1 is determined with a margin so as not to exceed the system upper limit rotational speed determined by the structure of motor generator MG1, the occurrence of overvoltage due to the power generation, the durability of planetary gears, and the like.

  If ΔNm2 ≦ Nt2 does not hold in step S1, the wheel is not locked and the overspeed as shown in FIG. 8 does not occur, so the process proceeds to step S5 and the control is transferred to the main routine. If Nm1 ≧ Nt1 does not hold, even if the rotational speed Nm1 of the motor generator MG1 increases due to the reaction of the wheel lock as shown in FIG. Then, the process proceeds to the main routine.

  When ΔNm2 ≦ Nt2 and Nm1 ≧ Nt1 are satisfied in step S1, the process proceeds to step S2, and for each of a plurality of cylinders (for example, four cylinders) of the internal combustion engine, the cylinders are ignited after fuel injection for each cylinder. It is determined whether it is before.

  For the cylinders that are not determined to be after fuel injection and before ignition in step S2, the process proceeds to step S4, and fuel injection is stopped by a fuel cut command. For this reason, the torque generated in the engine is reduced.

  In step S2, the process of step S3 is executed for the cylinder determined to be after fuel injection and before ignition. In step S3, the ignition timing is corrected by a map, and the torque generated in the engine in the combustion stroke is corrected. Decrease.

FIG. 4 is an example of an ignition timing correction map used in step S3 of FIG.
In FIG. 4, the horizontal axis indicates the engine speed (rpm), and the vertical axis indicates the engine load factor (%). Here, the load factor is obtained by the amount of intake air / the volume in the cylinder. The intake air amount is calculated based on the output of the air flow meter 104 in FIG.

  In step S3, the basic ignition timing map (usually indicated by the crank angle from the top dead center) determined to output the maximum torque is retarded by the correction amount defined by the map of FIG. Let The basic ignition timing is also called MBT (Minimum advance for Best Torque).

  In the region of low rotation speed and low load, the flow rate in the cylinder is low, and the amount of torque reduction is small even if the ignition timing is changed. For this reason, in the map shown in FIG. 4, the correction amount of the retard amount of the ignition timing is large in the low rotation speed and low load regions. That is, the timing is shifted larger than the ignition timing at which the maximum torque is output.

  FIG. 5 is a schematic diagram showing a state of fuel injection and ignition of each cylinder when the control of the flowchart of FIG. 3 is executed.

  Referring to FIG. 5, the fuel injection and ignition timing of cylinders # 1, # 3, # 4, and # 2 are shown in order from the top. A hatched rectangle indicates that fuel injection is being performed, and a portion indicated by “FC” indicates that fuel is cut and fuel injection is not performed.

  The cylinder # 1 will be described representatively. The periods T1, T2, T3, and T4 are an intake stroke, a compression stroke, a combustion stroke, and an exhaust stroke, respectively. In this order, the same stroke is repeated after the period T5. Fuel injection is performed from the exhaust stroke to the intake stroke. In addition, ignition is performed at a portion where the compression stroke shifts to the combustion stroke.

  Cylinder # 3 is performed in period T2 with the intake stroke shifted by one period compared to cylinder # 1. Cylinder # 4 is performed in period T3 with the intake stroke shifted by two periods compared to cylinder # 1. Cylinder # 2 is performed in period T4 with the intake stroke shifted by three periods compared to cylinder # 1. In cylinders # 2, # 3, and # 4, the stroke order, injection timing, and ignition timing are the same as in cylinder # 1, and therefore description thereof will not be repeated.

  Normal operation is performed during the period T1-T5. Now, assume that the process proceeds from step S1 to step S2 as a result of satisfying the condition of step S1 in FIG. Then, a torque reduction command for reducing the engine torque is sent from the HV-ECU 70 of FIG. 1 to the engine ECU 24.

  When the torque reduction command is given in the period T6, the cylinders # 4 and # 2 are ignited with respect to the fuel injected. Therefore, for cylinders # 4 and # 2, the process of step S4 is executed and fuel injection is stopped by fuel cut.

  On the other hand, when the torque reduction command is given in the period T6, the cylinders after fuel injection and before ignition are cylinders # 1 and # 3. Therefore, for cylinders # 1 and # 3, the process of step S3 is executed and the ignition timing is retarded.

  That is, the ignition timing of the cylinder # 1 is retarded near the boundary between the periods T6 and T7, and the ignition timing of the cylinder # 3 is retarded near the boundary between the periods T7 and T8. Thereafter, the process of step S4 is also executed for the cylinders # 1 and # 3, and fuel cut is performed.

  FIG. 6 is an operation waveform diagram for explaining the difference in occurrence of over-rotation between when the control of the present embodiment is executed and when it is not executed.

  Referring to FIG. 6, at time t0, the hybrid vehicle is running while the engine is running. Therefore, the engine rotates at the rotation speed Ne, and torque Te is output from the engine to the power split mechanism.

  At time t1, for example, when the driver steps on the brake, the wheels are locked. Then, it is detected that the number of rotations of motor generator MG2 has decreased rapidly. This detection is determined based on the determination condition of ΔNm2 ≦ Nt2 in step S1 of FIG.

  If the fuel cut command is simply output here without executing the control of the present embodiment, the fuel that has been injected at that time and that has not been ignited is also between t1 and t2. Since combustion is performed, the engine torque Te continues to be output as indicated by a broken line. For this reason, the amount of decrease of the arrow A2 in FIG. 8 cannot be reduced. As a result, at times t1 to t2, the rotational speed of motor generator MG1 increases by ND as shown by the rotational speed Nm1X indicated by the broken line, resulting in overspeeding.

  On the other hand, if the control of the present embodiment is executed, the engine torque Te can be quickly reduced at time t1 as shown by the solid line, and the time for extracting the torque by the delay time td is advanced, and the engine rotation The number Ne can also be decreased between times t1 and t2. Therefore, the motor generator MG1 is prevented from over-rotating as indicated by the rotational speed Nm1 indicated by the solid line.

  Finally, the present embodiment will be generally described. Referring to FIG. 1, the power output apparatus of the present embodiment includes an internal combustion engine (engine 22), a first rotating electrical machine (motor generator MG1), wheels 63a and 63b, and the rotation of the first rotating electrical machine. A power split mechanism (30) having a first rotating element linked to a shaft, a second rotating element linked to a rotating shaft of the internal combustion engine, and a third rotating element linked to a drive shaft for driving a wheel; And a control unit (70, 40, 52, 24) for controlling the first rotating electrical machine. When the rotational speed of the drive shaft (32a) changes in a decreasing direction exceeding the threshold value, the control unit executes torque reduction control for reducing the generated torque of the internal combustion engine. The torque reduction control includes a process of correcting the ignition timing so that the generated torque of the internal combustion engine is reduced, and a process of stopping fuel supply to the internal combustion engine.

  Preferably, the internal combustion engine includes a plurality of cylinders (FIG. 5: # 1 to # 4), a plurality of fuel injection valves (FIG. 2: 110) respectively corresponding to the plurality of cylinders, and a plurality of cylinders respectively corresponding to the plurality of cylinders. Ignition device (FIG. 2: 112). When executing the torque reduction control, the control unit corrects the retard amount of the ignition timing so that the generated torque of the internal combustion engine decreases for the cylinder after fuel injection and before ignition (FIG. 3: Step S3). ) The fuel injection is stopped for the cylinder after fuel injection and after ignition (FIG. 4: Step S4).

  More preferably, as shown in FIG. 4, the control unit determines a correction amount for the retard amount of the ignition timing in accordance with the rotational speed of the internal combustion engine and the load factor of the internal combustion engine.

  Preferably, the vehicle power output apparatus further includes a second rotating electrical machine (motor generator MG2) having a rotating shaft that is linked to the drive shaft (32a). The control unit executes power running and regeneration control of the first and second rotating electrical machines.

  According to the power output apparatus for a vehicle of the present embodiment, since the timing for reducing the torque generation of the engine can be shortened in order to prevent the occurrence of over-rotation, it is advantageous in preventing over-rotation of the drive system.

  In addition, since unburned fuel is not discharged in exchange for stopping the generation of engine torque, damage to the motor generator due to overspeed can be prevented without adversely affecting the environment.

  In addition, the control methods disclosed in the above embodiments can be executed by software using a computer. A program for causing a computer to execute this control method is read from a recording medium (ROM, CD-ROM, memory card, etc.) recorded in a computer-readable manner into a computer in a vehicle control device or provided through a communication line. You may do it.

  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.

It is the schematic of the structure of the hybrid vehicle 20 carrying the internal combustion engine as embodiment of this invention. 2 is a schematic diagram for explaining the periphery of an engine 22 of a vehicle 20. FIG. It is a flowchart for demonstrating control of the internal combustion engine in this Embodiment. It is an example of the correction map of the ignition timing used by step S3 of FIG. FIG. 4 is a schematic diagram showing a state of fuel injection and ignition of each cylinder when the control of the flowchart of FIG. 3 is executed. It is an operation waveform diagram for explaining the difference in the occurrence situation of overspeed when the control of the present embodiment is executed and when it is not executed. It is an alignment chart of an example using a planetary gear as a differential mechanism. It is a figure for demonstrating the change of the rotation speed at the time of a wheel lock.

Explanation of symbols

  20 hybrid vehicle, 22 engine, 24 electronic control unit for engine, 26 crankshaft, 28 damper, 30 power split mechanism, 31 sun gear, 32 ring gear, 32a ring gear shaft, 33 pinion gear, 34 carrier, 35 reduction gear, 41, 42 inverter , 43, 44 Rotational position detection sensor, 50 battery, 51 temperature sensor, 52 electronic control unit for battery, 54 power line, 60 gear mechanism, 62 differential gear, 63a wheel, 63a, 63b drive wheel, 70 electronic control unit for hybrid , 80 Ignition switch, 81 Shift lever, 82 Shift position sensor, 83 Accelerator pedal, 84 Accelerator pedal position sensor, 85 Brake pedal, 86 Brake pedal position Sensor, 88 vehicle speed sensor, 102 air cleaner, 104 air flow meter, 106 intake temperature sensor, 107 throttle valve, 108 electronic control throttle, 110 injector, 111 intake passage, 112 ignition coil, 113 exhaust passage, 114 piston, 127, 128 catalyst Device, 143 crank position sensor, 144 knock sensor, 145 air-fuel ratio sensor, 146 oxygen sensor, 148 water temperature sensor, MG1, MG2 motor generator.

Claims (7)

An internal combustion engine;
A first rotating electrical machine;
Wheels,
A first rotating element that is linked to the rotating shaft of the first rotating electrical machine, a second rotating element that is linked to the rotating shaft of the internal combustion engine, and a third rotating element that is linked to the drive shaft that drives the wheels. A power split mechanism;
A control unit for controlling the internal combustion engine and the first rotating electrical machine,
When the rotational speed of the drive shaft changes in a decreasing direction exceeding a threshold value, the control unit executes torque reduction control for reducing the generated torque of the internal combustion engine,
The torque reduction control is
A process of correcting the ignition timing so that the generated torque of the internal combustion engine is reduced;
A power output apparatus for a vehicle, including a process of stopping fuel supply to the internal combustion engine. The internal combustion engine
Multiple cylinders,
A plurality of fuel injection valves respectively corresponding to the plurality of cylinders;
A plurality of spark plugs respectively corresponding to the plurality of cylinders,
When performing the torque reduction control, the control unit corrects the retard amount of the ignition timing so that the generated torque of the internal combustion engine is reduced for the cylinder after the fuel injection and before the ignition, and after the fuel injection 2. The vehicle power output device according to claim 1, wherein fuel injection is stopped for the cylinder after ignition.   The power output device for a vehicle according to claim 2, wherein the control unit determines a correction amount of the retard amount of the ignition timing according to a rotation speed of the internal combustion engine and a load factor of the internal combustion engine. A second rotating electrical machine having a rotating shaft interlocking with the drive shaft;
The power output apparatus for a vehicle according to claim 1, wherein the control unit executes control of powering and regeneration of the first and second rotating electrical machines. An internal combustion engine, a first rotating electrical machine, a wheel, a first rotating element interlocked with a rotating shaft of the first rotating electrical machine, a second rotating element interlocked with the rotating shaft of the internal combustion engine, and the wheel. A power split device having a third rotating element interlocked with a drive shaft to be driven, and a control method for a vehicle power output device,
Determining whether the rotational speed of the drive shaft changes in a decreasing direction exceeding a threshold;
Executing a torque reduction control for reducing the torque generated by the internal combustion engine when the rotational speed of the drive shaft changes in a decreasing direction exceeding a threshold value,
The step of executing the torque reduction control includes:
Correcting the ignition timing so that the generated torque of the internal combustion engine decreases;
A method of controlling a vehicle power output apparatus, comprising: stopping fuel supply to the internal combustion engine. The internal combustion engine
Multiple cylinders,
A plurality of fuel injection valves respectively corresponding to the plurality of cylinders;
A plurality of spark plugs respectively corresponding to the plurality of cylinders,
The step of correcting the ignition timing corrects the retard amount of the ignition timing with respect to the cylinder after the fuel injection and before the ignition so that the generated torque of the internal combustion engine decreases when the torque reduction control is executed,
The method for controlling a power output apparatus for a vehicle according to claim 5, wherein the step of stopping the fuel supply stops the fuel injection to the cylinder after the fuel injection and after the ignition.   The vehicle power output according to claim 5, wherein the step of correcting the ignition timing determines a correction amount of a retard amount of the ignition timing according to a rotation speed of the internal combustion engine and a load factor of the internal combustion engine. Device control method.

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