JP5007621B2 - Regenerative control device for hybrid vehicle - Google Patents

Description

  The present invention relates to a hybrid vehicle including a prime mover in which an internal combustion engine having a mechanism for changing an effective compression ratio and an electric motor are connected, and a response at the time of reacceleration while increasing the regeneration efficiency by the electric motor functioning as a generator during deceleration. The present invention relates to a control technology that ensures safety.

Patent Document 1 discloses a technique for regenerating by converting a braking force into electric power by causing an electric motor to function as a generator during deceleration in the hybrid vehicle.
JP 10-023603 A

  In a hybrid vehicle that regenerates at the time of deceleration as in Patent Document 1, in the case of a system configuration in which the internal combustion engine and the electric motor cannot be separated at the time of deceleration regeneration, the amount of regeneration due to vibration caused by the rotation of the internal combustion engine or the friction loss of the engine Decrease.

  For this reason, in an internal combustion engine equipped with a mechanism for reducing the effective compression ratio, a method of reducing the effective compression ratio to suppress vibration and increasing the regeneration amount when performing regeneration during deceleration.

  However, in this method, if a high output request such as full-open acceleration occurs during the reduction of the effective compression ratio, the output request cannot be sufficiently satisfied due to the release response delay of the effective compression ratio reduction mechanism, and a good acceleration feeling cannot be obtained. .

  The present invention has been made paying attention to such a conventional problem, and when reaccelerating from a regenerative state while reducing the compression ratio at the time of deceleration, the engine torque response is improved and good acceleration is achieved. The purpose is to get a feeling.

For this reason, the present invention
In a regenerative control device for a hybrid vehicle that regenerates the motor by generating power as a generator during deceleration of a hybrid vehicle equipped with an internal combustion engine having a mechanism for changing an effective compression ratio and a motor connected to the motor, The following configuration was adopted.

  During the regeneration, when the brake is being operated, the effective compression ratio is reduced, and the regeneration amount of the power generation is corrected to be increased according to the reduction of the effective compression ratio.

  When the brake operation is released, the reduction of the effective compression ratio is released.

  The fuel consumption can be improved by reducing the effective compression ratio and reducing the rotational resistance of the engine during the braking operation to increase the regeneration amount, and the vibration can be reduced by reducing the rotational resistance of the engine.

  Also, when reaccelerating from a state where the effective compression ratio is reduced and regenerating, the reduction of the effective compression ratio starts in the engine brake state where the brake operation is released, so when depressing the accelerator and accelerating Since the engine output is already increased and accelerated while the effective compression ratio is increased, a good feeling of acceleration can be obtained.

  FIG. 1 schematically shows a drive system of a hybrid vehicle according to an embodiment of the present invention.

  The output shaft of the engine (internal combustion engine) 1 and one end portion of the output shaft of the motor (electric motor) 2 are connected, and the other end portion of the motor 2 has a gear ratio by changing the input / output pulley diameter ratio. A continuously variable transmission 3 that is variably controlled continuously is connected, and an output shaft (output pulley shaft) of the continuously variable transmission 2 is connected to one end of a gear shaft 5 via a clutch 4. The transmission is not limited to the continuously variable transmission and may be a stepped transmission.

  The gear 5a fixed to the gear shaft 5 meshes with a gear 7a fixed to an axle (drive shaft) 7 having wheels 6 connected to both ends, and the driving force of the engine 1 and the motor 2 is used for the continuously variable transmission. 3, and transmitted to the wheel 6 through the clutch 4, the gear 5 a, the gear 7 a, and the axle 7.

  In addition, a battery (power storage device) 9 is connected to the motor 2 via an inverter 8. When the motor 2 functions as an electric motor, electric power is supplied from the battery 9, and when the motor 2 functions as a generator, The generated power is charged in the battery 9.

  FIG. 2 shows an example of the engine 1.

  The engine 1 is a diesel engine, and intake air is drawn into the cylinder 28 from an air cleaner 22 through an intake passage 23, a collector 24, an intake manifold 25, and an intake valve 26 that is driven to open and close by an intake cam 26.

  A piston 29 is fitted into the cylinder 28 and fuel is injected and supplied by a fuel injection valve 30. The combustion exhaust is discharged to the exhaust passage 33 through an exhaust valve 32 that is opened and closed by an exhaust cam 31.

  A part of the exhaust is introduced into the EGR passage 34 as EGR gas, and is returned to the intake manifold 25 while the EGR amount is controlled by the EGR valve 35.

  As a mechanism for changing the effective compression ratio of the engine 1, a variable valve timing mechanism 36 for changing the valve timing of the intake valve 27 (hereinafter referred to as a VTC angle θv as an advance amount from the operating angle center) is provided.

  Here, by the variable valve timing mechanism 36, the closing timing IVC of the intake valve 27 is further away from the bottom dead center as the VTC angle θv is retarded, and the effective compression ratio is decreased as the VTC angle θv is advanced. The compression ratio decreases. When the intake valve closes before intake bottom dead center, the effective compression ratio decreases by advancing the intake valve closing timing IVC.

  Changing the effective compression ratio is substantially equivalent to changing the compression pressure at the compression top dead center, that is, changing the charging efficiency of the intake air. In addition to the variable valve timing mechanism, a variable valve lift mechanism that changes the operating angle or lift amount of the intake valve, an intake throttle mechanism using an intake throttle valve, or the like may be used.

  Of course, the engine 1 may be a gasoline engine.

  Returning to FIG. 1, the ECU (electronic control unit) 10 includes an accelerator sensor 51 that detects an accelerator pedal depression amount APS, a brake sensor 52 that detects a brake pedal depression amount BPS, and an engine rotation speed Ne (= motor rotation speed). , A battery voltage Vb for detecting the state of charge (SOC) of the battery 9, and other detection signals from various sensors for detecting the operating state.

  The ECU 10 calculates the required output of the engine 1 and the motor 2 based on the operation information of the driver obtained from the detection signal, the driving state information, the state of charge (SOC) information of the battery 9, and the like, and commands according to the required output The value is output to control the engine 1, the motor 2, the inverter 8, and the like. Moreover, the presence or absence of the request | requirement of regeneration which operates the motor 2 as a generator is determined, and when there exists a regeneration request | requirement, the command value according to a request | requirement is output and regeneration control is performed.

  Here, when performing regeneration during deceleration, the variable valve timing mechanism 36 reduces the effective compression ratio during brake operation, decreases the rotational resistance of the engine 1, and increases the power generation torque of the motor 1 by that amount, Increase the regeneration amount.

  Hereinafter, the regeneration amount correction control will be described with reference to the flowchart of FIG.

  In step S1, it is determined whether the accelerator pedal is depressed (accelerator pedal stroke> 0) based on the signal from the accelerator sensor 51. If it is determined that the accelerator pedal is not depressed, in step S2, It is determined whether the brake pedal is depressed (brake pedal stroke> 0).

  If it is determined in step S2 that the brake pedal is being depressed, the process proceeds to step S3, where it is determined whether the charge amount SOC of the battery 9 is equal to or less than the overcharge prevention threshold value SOCh, and is equal to or less than the threshold value SOCh. When it is determined, the process proceeds to step S4 and subsequent steps, and the regeneration amount increase correction is executed.

  In step S4, a command value for the VTC angle θv by the variable valve timing mechanism 36 is calculated.

  Specifically, according to the characteristics shown in FIG. 4, the VTC angle θv is retarded in accordance with the increase in the brake pedal stroke BPS, and the effective compression ratio of the engine 1 is decreased.

  In step S5, the command value of the VTC angle θv calculated as described above is output to the variable valve timing mechanism 36, and the valve timing of the intake valve 27 during brake operation is controlled.

  In step S6 and subsequent steps, the regeneration amount during the brake operation is corrected according to the reduction amount of the effective compression ratio due to the VTC angle θv.

  In step S6, an increase correction amount of the power generation torque of the motor 1 is calculated as an increase correction amount of the regeneration amount. Specifically, according to the characteristics shown in FIG. 5, the increase correction amount dTg is calculated as a larger value as the effective compression ratio decreases.

  In step S7, the increase correction amount dTg calculated as described above is output, and the power generation torque of the motor 1 is corrected. Specifically, as the increase correction amount dTg is larger, the field current of the motor 1 is increased to increase the power generation torque.

  As a result, as shown in FIG. 6, as the brake depression amount BPS increases, the VTC angle θv is retarded, the effective compression ratio decreases, the increase correction amount dTg increases, and the regeneration amount further increases.

  Moreover, since the increase correction amount dTg of the power generation torque is increased to match the decrease in the rotational resistance of the engine 1 due to the decrease in the effective compression ratio, the braking force does not change and the braking performance is also satisfied.

  In this way, when the brake pedal is released from the state where the regeneration amount increase correction is being performed during the brake operation and the engine shifts to the coast deceleration by the engine brake, the determination in step S2 becomes NO, and the process proceeds to step S8. The retardation correction of the VTC angle θv by the variable valve timing mechanism 36 is cancelled.

  As a result, the reduction in the effective compression ratio of the engine 1 is released, and thereafter, the effective compression ratio can be increased by the time when the accelerator pedal is depressed to re-accelerate. A feeling of acceleration can be obtained.

  FIG. 7 shows a timing chart at the time of control in the embodiment.

  At time t0, coast deceleration regeneration is in effect, and the VTC angle θv is the most advanced angle side and the effective compression ratio is not reduced.

  When the amount of brake pedal gradually increases by the driver's operation between t1 and t2, the VTC angle θv is retarded according to the amount of brake pedal depression. Further, the power generation torque increase correction amount dTg increases from zero.

  When the brake pedal is released by the driver at t3, the power generation torque increase correction amount dTg decreases, and the coast regeneration state is reached, and the VTC angle θv returns to the advance side at t4.

  Although the accelerator pedal is greatly depressed at t5, since the reduction in the effective compression ratio of the engine 1 is released, the engine can be operated with a sufficient torque response.

  As described in the above embodiment, while reducing the effective compression ratio of the engine 1 during the brake operation, the fuel consumption can be improved by performing the increase correction of the regeneration amount according to the reduction of the effective compression ratio. The engine vibration can be reduced by reducing the effective compression ratio.

  Also, when reaccelerating from a state where the effective compression ratio is reduced and regenerating, the reduction of the effective compression ratio starts in the engine brake state where the brake operation is released, so when depressing the accelerator and accelerating Since the engine output is already increased and accelerated while the effective compression ratio is increased, a good feeling of acceleration can be obtained.

  In the present embodiment, the effective compression ratio is changed almost simultaneously by all the cylinders by the variable valve timing mechanism 36, and the effective compression ratio can be reduced and cancelled with good response.

  In addition, since the variable valve timing mechanism 36 can be continuously changed, the reduction amount of the effective compression ratio is increased as the brake operation amount is increased. Therefore, the compression ratio return completion timing is compared with the generation timing of the acceleration request. While suppressing this delay, the effective compression ratio can be further reduced to increase the regeneration amount and increase the vibration reduction effect. In addition, the setting of the braking force with respect to the brake depression amount is kept constant, and the brake feeling can be kept good.

  Further, when the charge amount SOC of the battery 9 exceeds the overcharge prevention threshold value SOCh, the reduction of the effective compression ratio and the increase correction of the regenerative amount accompanying the reduction are prohibited. Overcharge can be suppressed.

The figure which shows the outline of the drive system of the hybrid vehicle which concerns on one Embodiment of this invention. The figure which shows an example of the engine of embodiment same as the above. The flowchart which shows correction | amendment control of the regeneration amount of embodiment same as the above. The figure which shows the characteristic of the effective compression ratio with respect to the brake depression amount in embodiment same as the above. The figure which shows the characteristic of the increase correction amount of the electric power generation torque with respect to an effective compression ratio in embodiment same as the above. The figure which shows the characteristic of the target electric power generation torque with respect to the brake depression amount in embodiment same as the above. The figure which shows the mode of the change of various state quantities at the time of performing control at the time of the regeneration which concerns on this invention.

Explanation of symbols

1 engine (internal combustion engine)
2 Motor (electric motor)
9 Battery 10 Electronic control unit 51 Acceleration sensor 52 Brake sensor

Claims (6)

In a regenerative control device for a hybrid vehicle that regenerates the motor by generating power as a generator during deceleration of a hybrid vehicle equipped with an internal combustion engine having a mechanism for changing an effective compression ratio and a motor connected to the motor,
During the regeneration, when the brake is being operated, while reducing the effective compression ratio, the regeneration amount of the power generation is corrected to be increased according to the reduction in the effective compression ratio, and when the brake operation is released, the effective compression ratio is reduced. The regenerative control device for a hybrid vehicle is characterized by canceling the reduction of the vehicle.   A mechanism for changing the effective compression ratio is provided for each cylinder. During regeneration, the effective compression ratio of all cylinders is reduced when the brake is operated, and the effective compression ratio of all cylinders is reduced when the brake operation is released. The regenerative control device for a hybrid vehicle according to claim 1, wherein:   The regenerative control of a hybrid vehicle according to claim 1 or 2, wherein as the brake operation amount during regeneration is larger, the reduction amount of the effective compression ratio is increased and the increase correction amount of the regeneration amount is increased. apparatus.   The control for reducing the effective compression ratio during the regeneration is prohibited when the charge amount of the power storage device that supplies electric power to the electric motor exceeds a threshold for preventing overcharge. The regeneration control device for a hybrid vehicle according to any one of 3.   The regenerative control device for a hybrid vehicle according to any one of claims 1 to 4, wherein the mechanism for changing the effective compression ratio is capable of continuously changing the effective compression ratio.   The hybrid regeneration control apparatus according to any one of claims 1 to 5, wherein the mechanism that changes the effective compression ratio is a mechanism that varies a valve characteristic of an intake valve of an internal combustion engine.

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