JP2012158328A - Controller for hybrid vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a controller for hybrid vehicle, capable of concurrently accommodating both cranking torque and vehicle driving torque in shifting from EV mode to HEV mode.SOLUTION: The controller for a hybrid vehicle, which includes an engine, a motor and a fastening element interposed between the engine and the motor for connecting/disconnecting the engine to/from the motor, fastens the fastening element and starts the engine using the torque of the motor, is provided with an engine stop control means that disconnects the fastening element after the rotational speed of the engine is not more than a predetermined speed in stopping the engine when the engine is stopped in a driving mode for driving using the engine and the motor torque.

Description

  The present invention relates to a control apparatus for a hybrid vehicle having an engine and a motor as a power source.

  The technique of patent document 1 is disclosed as a hybrid vehicle. In this technique, when the brake is operated during regeneration by the motor during deceleration in the HEV mode (mode in which the engine and the motor run), the engine is stopped and the engine-motor clutch is engaged. Liberated. In addition, when shifting from the brake operation state to the non-operation state while the engine is stopped, the clutch is connected and the engine is restarted when the change amount of the operation input to the brake exceeds a predetermined value.

JP 2002-144921 A

  However, in the above prior art, in order to allow the engine to stop when the motor rotates at a high speed, the motor is shifted to the EV mode (a mode in which the vehicle runs only by the motor torque) while maintaining a high speed.

  Since the motor has a characteristic that the torque decreases as the rotation speed becomes higher, the motor torque at the time of the higher rotation speed is insufficient to cover both the cranking torque for starting the engine and the driving torque of the vehicle. Therefore, when shifting from the EV mode to the HEV mode at the time of high rotation of the motor, there is a possibility that the cranking torque for restarting the engine is insufficient.

  The present invention has been made paying attention to the above-mentioned problem, and the object of the present invention is to provide a hybrid vehicle capable of providing both cranking torque and vehicle driving torque when shifting from the EV mode to the HEV mode. It is to provide a control device.

  In order to achieve the above object, according to the present invention, in a hybrid vehicle control device that fastens a fastening element and starts an engine using the torque of a motor, at the time of executing an engine use travel mode that travels using the torque of the engine and the motor. When stopping the engine, an engine stop control means for releasing the fastening element is provided after the engine speed becomes equal to or lower than the predetermined speed.

  Therefore, it is possible to provide a control device for a hybrid vehicle that can cover both cranking torque and vehicle driving torque when shifting from the EV mode to the HEV mode.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an overall system diagram illustrating a rear-wheel drive hybrid vehicle according to a first embodiment. FIG. 3 is a control block diagram illustrating an arithmetic processing program in the integrated controller according to the first embodiment. It is a figure which shows an example of the target driving force map used for target driving force calculation in the target driving force calculating part of FIG. It is a figure which shows an example of the target charging / discharging amount map used for the calculation of target charging / discharging electric power in the target charging / discharging calculating part of FIG. It is a figure which shows the mode map used for selection of the target mode in the mode selection part of FIG. It is a rotation speed-torque characteristic view of a motor. It is an engine stop control flow. It is a time chart of engine stop control.

  DESCRIPTION OF EMBODIMENTS Hereinafter, a mode for realizing a control device for a hybrid vehicle of the present invention will be described based on an embodiment shown in the drawings.

  First, the drive system configuration of the hybrid vehicle will be described. FIG. 1 is an overall system diagram showing a hybrid vehicle by rear wheel drive to which the engine start control device of the first embodiment is applied. As shown in FIG. 1, the drive system of the hybrid vehicle in the first embodiment includes an engine E, a first clutch CL1 (engagement element), a motor MG, a second clutch CL2, and an automatic transmission AT (stepped transmission). Machine), a propeller shaft PS, a differential DF, a left drive shaft DSL, a right drive shaft DSR, a left rear wheel RL (drive wheel), and a right rear wheel RR (drive wheel). Note that FL is the left front wheel, and FR is the right front wheel.

  The engine E is, for example, a gasoline engine, and the valve opening degree of the throttle valve and the like are controlled based on a control command from the engine controller 1 described later. The engine output shaft is provided with a flywheel FW.

  The first clutch CL1 is a clutch interposed between the engine E and the motor MG, and the control hydraulic pressure generated by the first clutch hydraulic unit 6 based on a control command from the first clutch controller 5 described later. And the fastening / release including the slip fastening is controlled.

  The motor MG is a synchronous motor in which a permanent magnet is embedded in a rotor and a stator coil is wound around a stator, and a three-phase AC generated by an inverter 3 is applied based on a control command from a motor controller 2 described later. Is controlled. The motor MG can operate as an electric motor that is driven to rotate by receiving power supplied from the battery 4 (hereinafter, this state is referred to as “powering”), and when the rotor is rotated by an external force. The battery 4 can also be charged by functioning as a generator that generates electromotive force at both ends of the stator coil (hereinafter, this operation state is referred to as “regeneration”). The rotor of the motor MG is connected to the input shaft of the automatic transmission AT via a damper (not shown).

  The second clutch CL2 is a clutch interposed between the motor MG and the left and right rear wheels RL, RR, and is created by the second clutch hydraulic unit 8 based on a control command from the AT controller 7 described later. Fastening / release including slip fastening is controlled by the control hydraulic pressure.

  The automatic transmission AT is a transmission that automatically switches stepped gear ratios such as forward 5 speed, reverse 1 speed, etc. according to vehicle speed, accelerator opening, etc., and the second clutch CL2 is newly added as a dedicated clutch However, some frictional engagement elements are used among a plurality of frictional engagement elements that are engaged at each gear stage of the automatic transmission AT.

  The output shaft of the automatic transmission AT is connected to the left and right rear wheels RL and RR via a propeller shaft PS, a differential DF, a left drive shaft DSL, and a right drive shaft DSR as vehicle drive shafts. The first clutch CL1 and the second clutch CL2 are, for example, wet multi-plate clutches that can continuously control the oil flow rate and hydraulic pressure with a proportional solenoid.

  This hybrid drive system has three travel modes according to the engaged / released state of the first clutch CL1. The first travel mode is an electric vehicle travel mode (hereinafter abbreviated as “EV travel mode”) as a motor use travel mode in which the first clutch CL1 is disengaged and travels using only the power of the motor MG as a power source. is there. The second travel mode is an engine use travel mode (hereinafter abbreviated as “HEV travel mode”) in which the first clutch CL1 is engaged and the engine E is included in the power source. The third travel mode is an abbreviated engine use slip travel mode (hereinafter referred to as “WSC travel mode”) in which the second clutch CL2 is slip-controlled while the first clutch CL1 is engaged and the engine E is included in the power source. ). This mode is a mode in which creep running can be achieved particularly when the battery storage amount (battery SOC) is low or when the engine water temperature is low. When transitioning from the EV travel mode to the HEV travel mode, the first clutch CL1 is engaged and the engine is started using the torque of the motor MG.

  The “HEV travel mode” has three travel modes of “engine travel mode”, “motor assist travel mode”, and “travel power generation mode”.

  In the “engine running mode”, the drive wheels are moved using only the engine E as a power source. In the “motor-assisted travel mode”, the drive wheels are moved using the engine E and the motor MG as power sources. In the “traveling power generation mode”, the drive wheels RR and RL are moved using the engine E as a power source, and at the same time, the motor MG functions as a generator.

  During constant speed operation or acceleration operation, the motor MG is operated as a generator using the power of the engine E. Further, during deceleration operation, braking energy is regenerated and electric power is generated by the motor MG and used for charging the battery 4.

  Further, as a further mode, there is a power generation mode in which the motor MG is operated as a generator using the power of the engine E when the vehicle is stopped.

  Next, the control system of the hybrid vehicle will be described. As shown in FIG. 1, the hybrid vehicle control system according to the first embodiment includes an engine controller 1, a motor controller 2, an inverter 3, a battery 4, a first clutch controller 5, and a first clutch hydraulic unit 6. The AT controller 7, the second clutch hydraulic unit 8, the brake controller 9, and the integrated controller 10 are configured. The engine controller 1, the motor controller 2, the first clutch controller 5, the AT controller 7, the brake controller 9, and the integrated controller 10 are connected via a CAN communication line 11 that can exchange information with each other. Has been.

  The engine controller 1 inputs the engine speed information from the engine speed sensor 12, and controls the engine operating point (Ne: engine speed, Te: engine torque) according to the target engine torque command from the integrated controller 10 and the like. For example, to a throttle valve actuator (not shown). Information such as the engine speed Ne is supplied to the integrated controller 10 via the CAN communication line 11.

  The motor controller 2 inputs information from the resolver 13 that detects the rotor rotational position of the motor MG, and according to a target motor torque command from the integrated controller 10 or the like, the motor operating point of the motor MG (Nm: motor rotational speed, Tm : Motor torque) is output to the inverter 3.

  In this motor controller 2, the battery SOC detection means 201 monitors the battery SOC indicating the state of charge of the battery 4, and the battery SOC information is used for control information of the motor MG and via the CAN communication line 11. Supplied to the integrated controller 10.

  The first clutch controller 5 inputs sensor information from the first clutch hydraulic pressure sensor 14 and the first clutch stroke sensor 15, and according to the first clutch control command from the integrated controller 10, the first clutch CL1 is engaged / released. A command to control is output to the first clutch hydraulic unit 6. Information on the first clutch stroke C1S is supplied to the integrated controller 10 via the CAN communication line 11.

  The AT controller 7 inputs sensor information from an accelerator opening sensor 16, a vehicle speed sensor 17, a second clutch hydraulic pressure sensor 18, and an inhibitor switch that outputs a signal corresponding to the position of the shift lever operated by the driver. 10 is output to the second clutch hydraulic unit 8 in the AT hydraulic control valve in response to the second clutch control command from 10. Information on the accelerator pedal opening APO, the vehicle speed VSP, and the inhibitor switch is supplied to the integrated controller 10 via the CAN communication line 11.

  The brake controller 9 inputs sensor information from the wheel speed sensor 19 and the brake stroke sensor 20 that detect the wheel speeds of the four wheels. For example, when the brake is depressed, braking is performed with respect to the required braking force obtained from the brake stroke BS. When the braking force alone is insufficient, the regenerative cooperative brake control is performed based on the regenerative cooperative control command from the integrated controller 10 so that the shortage is supplemented by the mechanical braking force (braking force by the friction brake).

  The integrated controller 10 manages the energy consumption of the entire vehicle and has a function for running the vehicle with the highest efficiency. The integrated controller 10 detects the motor rotational speed Nm, and the second clutch output rotational speed N2out. A second clutch output rotational speed sensor 22 for detecting the second clutch transmission torque capacity TCL2, a second clutch torque sensor 23 for detecting the second clutch transmission torque capacity TCL2, a brake hydraulic pressure sensor 24, and a temperature sensor 10a for detecting the temperature of the second clutch CL2. The information from the G sensor 10b for detecting the longitudinal acceleration and the information obtained via the CAN communication line 11 are input.

  Further, the integrated controller 10 controls the operation of the engine E based on the control command to the engine controller 1, the operation control of the motor MG based on the control command to the motor controller 2, and the first clutch based on the control command to the first clutch controller 5. The engagement / release control of CL1 and the engagement / release control of the second clutch CL2 by a control command to the AT controller 7 are performed.

  Below, the control calculated by the integrated controller 10 of Example 1 is demonstrated using the block diagram shown in FIG. For example, this calculation is performed by the integrated controller 10 every control cycle of 10 msec. The integrated controller 10 includes a target driving force calculation unit 100, a mode selection unit 200, a target charge / discharge calculation unit 300, an operating point command unit 400, and a shift control unit 500.

  The target driving force calculation unit 100 calculates a target driving force tFo0 from the accelerator pedal opening APO and the vehicle speed VSP using the target driving force map shown in FIG.

  The mode selection unit 200 selects a target mode based on the mode map. FIG. 5 shows a mode map. The mode map has an EV travel mode, a WSC travel mode, and an HEV travel mode, and the target mode is calculated from the accelerator pedal opening APO and the vehicle speed VSP. However, even if the EV travel mode is selected, if the battery SOC is equal to or lower than a predetermined value, the “HEV travel mode” or the “WSC travel mode” is forcibly set as the target mode.

  The target charge / discharge calculation unit 300 calculates the target charge / discharge power tP from the battery SOC using the target charge / discharge amount map shown in FIG. In the target charge / discharge amount map, the EVON line for permitting or prohibiting the EV travel mode is set to SOC = 50%, and the EVOFF line is set to SOC = 35%.

  When SOC ≧ 50%, the EV travel mode area appears in the mode map of FIG. Once the EV travel mode area appears in the mode map, this area continues to appear until the SOC falls below 35%.

  When SOC <35%, the EV travel mode area disappears in the mode map of FIG. When the EV travel mode area disappears from within the mode map, this area continues to disappear until the SOC reaches 50%.

  In the operating point command unit 400, the transient target engine torque is set as the operating point reaching target from the accelerator pedal opening APO, the target driving force tFo0, the target mode, the vehicle speed VSP, and the target charge / discharge power tP. And a target motor torque, a target second clutch engagement capacity, a target gear position of the automatic transmission AT, and a first clutch solenoid current command which is a transmission torque capacity command of the first clutch CL1. Further, the operating point command unit 400 starts the engine E when transitioning from the EV traveling mode to the HEV traveling mode.

  The operating point command unit 400 includes an engine stop control unit 401 (engine stop control means) that performs stop control of the engine E. The engine stop control unit 401 executes engine stop control described later.

[Engine stop control]
FIG. 6 is a rotational speed-torque characteristic diagram of the motor MG. Since the motor MG has a characteristic that the torque decreases as the rotational speed increases, in the hybrid vehicle that starts the engine using the torque of the motor MG as in the present application, the motor MG remains in the HEV mode while the motor MG remains at a high speed. When the EV mode is entered, there is a risk that cranking torque for starting the engine will be insufficient. Therefore, there is a possibility that the engine is not properly started when shifting from the EV mode to the HEV mode again.

  Therefore, in the present application, when shifting from the HEV mode to the EV mode, the engine stop control unit 401 releases the first clutch CL1 after the engine speed has become equal to or lower than the predetermined speed α, and performs fuel cut to stop the engine E. Let As a result, the engine E is stopped after the motor MG is lowered to a rotation speed suitable for the cranking torque and the vehicle driving torque. Therefore, when the engine E is started again, the cranking is performed smoothly and the vehicle is driven. It becomes possible.

  The predetermined rotational speed α is set for each of a plurality of gear ratios of the automatic transmission AT. The time from the start of disengagement of the first clutch CL1 to the complete disengagement is substantially constant. On the other hand, since the inertia is different for each gear having a plurality of gear ratios, the rotational speed lowering speed of the motor MG is different for each gear ratio, and is slower at a high gear and faster at a low gear. Therefore, if the predetermined rotation speed α at which the first clutch CL1 is started to be released is fixed, the engine rotation speed at the time of the complete release of the first clutch CL1 greatly deviates from the engine stop permission rotation speed β depending on the gear position at the start of the release. May be a value.

  Therefore, by setting the value of the predetermined rotational speed α at which the first clutch CL1 starts to be released for each of a plurality of shift speeds, the first clutch CL1 is completely disengaged at any shift speed. At the time of release, the engine speed is set near the engine stop permission speed β.

[Engine stop control process]
FIG. 7 is an engine stop control flow. Hereinafter, each step will be described.
In step S101, it is determined whether or not the engine rotational speed ≦ the predetermined rotational speed α. If NO, the control is terminated, and if YES, the process proceeds to step S102.

In step S102, the release control of the first clutch CL1 is started. Further, a zero torque control command is output to the engine E.
If the engine torque is output when the first clutch CL1 is released, the engine torque that has been transmitted to the drive wheels RL and RR until then is not transmitted suddenly when the first clutch CL1 is released. The rings RL and RR vibrate. Therefore, the engine torque is set to 0 beforehand by zero torque control, and the vibration when the first clutch CL1 is released is suppressed.

  In step S103, it is determined whether or not the first clutch CL1 is released based on the differential rotation. If YES, the process proceeds to step S104, and if NO, the control is terminated.

  In step S104, the self-sustained operation control of the engine E is started assuming that the release of the first clutch CL1 is completed, and the process proceeds to step S105.

In step S105, it is determined whether or not the VTC (variable valve timing control mechanism) is the most retarded and the rotational speed of the engine E is equal to or lower than the engine stop permission rotational speed β (rotational speed to prevent excessive exhaust gas at restart: described later). If YES, the process proceeds to step S106, and if NO, the control is terminated.
Since noise is generated when the VTC is not at the most retarded position when the engine E is restarted, the noise is suppressed by returning the VTC to the most retarded position in advance.
Further, when the engine E does not decrease in rotation and is restarted at a high speed, the exhaust gas of the engine E at the time of restart becomes excessive. Therefore, by stopping the engine speed after lowering the engine speed to the engine stop permission speed β or less in advance, restart is not performed while the engine speed remains high, and exhaust gas does not increase.

  In step S106, fuel cut (F / C) of the engine E is performed, and the process proceeds to step S107.

  In step S107, the engine speed becomes 0 and the control is terminated.

[Changes in engine stop control over time]
FIG. 8 is a time chart of engine stop control. Note that r1 to r4 indicate the number of rotations during a shift at each shift stage of the automatic transmission AT.
(Time t1)
At time t1, the driver's foot is released from the accelerator pedal, the fuel cut of the engine E is performed, and the engine speed decreases. The rotation speed of the motor MG connected to the engine E is also reduced by the first clutch CL1.

(Time t2)
At time t2, engine rotational speed ≦ predetermined rotational speed α, so that release control of the first clutch CL1 is started and zero torque control is performed on the engine E.

(Time t3)
At time t3, the first clutch CL1 is released. As a result, the engine speed and the motor speed deviate from each other, and the self-sustained operation of the engine E is started to decrease the engine speed. Note that the motor speed is maintained at a speed suitable for re-cranking.

(Time t4)
At time t4, the VTC is set to the most retarded angle, the engine speed is equal to or less than the engine stop permission speed β, the fuel cut of the engine E is performed, and then the engine speed becomes zero.

[Effect of Example 1]
(1) In the hybrid vehicle control device having the first clutch CL1 (engagement element) for connecting / releasing the engine E and the motor MG,
When the engine E is stopped during execution of the HEV mode (engine use travel mode) that travels using the torque of the engine E and the motor MG, the first clutch CL1 is released after the rotational speed of the engine E becomes equal to or lower than the predetermined rotational speed α. An engine stop control unit 401 (engine stop control means) to be released is provided.

  As a result, the engine E is stopped after the motor MG is lowered to a predetermined rotational speed α suitable for the cranking torque. Therefore, when the engine E is started again, both the cranking torque and the vehicle driving torque can be covered. it can.

(2) An automatic transmission AT (stepped transmission) having a plurality of gear ratios is provided,
The automatic transmission AT is interposed between the engine E and the motor MG and the drive wheels RL and RR.
The predetermined rotational speed α is set for each of a plurality of gear ratios.

The time from the start of disengagement of the first clutch CL1 to the complete disengagement is substantially constant. On the other hand, since the inertia is different for each gear having a plurality of gear ratios, the rotational speed lowering speed of the motor MG is different for each gear ratio, and is slower at a high gear and faster at a low gear.
Therefore, if the predetermined rotation speed α at which the first clutch CL1 is started to be released is fixed, the engine speed when the first clutch CL1 is completely released differs greatly from the engine stop permission rotation speed β depending on the shift speed at the start of the release. May result in
Therefore, by setting the value of the predetermined rotational speed α at which the first clutch CL1 starts to be released for each of a plurality of shift speeds, the first clutch CL1 is completely disengaged at any shift speed. At the time of release, the engine speed can be set near the engine stop permission speed β.

  As mentioned above, although demonstrated based on the Example, it is not restricted to the said structure, Other structures can be taken in the range which does not deviate from the scope of the present invention.

CL1 first clutch (engagement means)
E Engine MG Motor RL, RR Drive wheel 401 Engine stop control unit (engine stop control means)

Claims (3)

Engine,
A motor,
A fastening element interposed between the engine and the motor and connecting / releasing the engine and the motor;
In the hybrid vehicle control device for fastening the fastening element and starting the engine using the torque of the motor,
Engine stop control means for releasing the fastening element when the engine is stopped at a predetermined speed or less when the engine is stopped during execution of an engine use travel mode that travels using the torque of the engine and the motor. A control apparatus for a hybrid vehicle characterized by comprising: In the hybrid vehicle control device according to claim 1,
The hybrid vehicle control apparatus, wherein the engine stop control means performs zero torque control for controlling the engine so that torque of the engine is not transmitted to driving wheels when releasing the fastening element. In the hybrid vehicle control device according to claim 1 or 2,
A variable valve timing control mechanism for variably controlling the valve timing of the engine;
The engine stop control means performs the fuel cut of the engine after determining that the variable valve timing control mechanism is at the most retarded position after releasing the fastening element. apparatus.

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