JP4935797B2 - Electric vehicle control device - Google Patents

Description

  The present invention relates to a control device for an electric vehicle in which a friction clutch by hydraulic engagement is interposed between a motor generator and a drive wheel, and when braking is requested, a regenerative braking torque is applied to the drive wheel through the friction clutch.

As a regenerative braking control device in a conventional electric vehicle, there are an automatic transmission that achieves a plurality of shift speeds by fastening and releasing a plurality of fastening elements, and a motor that is provided on the input side of the automatic transmission and applies a regenerative torque There is known a generator including a generator that limits regenerative torque generated by a motor generator when an automatic transmission shifts (for example, see Patent Document 1).
JP 2008-94332 A

  However, in a regenerative braking control device in a conventional electric vehicle, slippage of the friction clutch increases if the amount of oil supplied to the engaging element (friction clutch) in the automatic transmission is temporarily insufficient during regenerative braking. As a result, the regenerative braking torque transmitted through the sliding friction clutch decreases. Therefore, regenerative braking is performed over a long period from the time when the friction clutch slips, until the shortage of oil supply is resolved, the friction clutch slips converge due to the increase in the engagement hydraulic pressure, and the friction clutch returns to the engagement state. Torque remains reduced. As a result, there has been a problem that a desired vehicle deceleration cannot be secured and a desired regeneration amount cannot be secured.

  The present invention was made paying attention to the above problem, and when the friction clutch is in a slipping state during regenerative braking, the friction clutch is shifted to the fastening state without shock and early from the occurrence of slipping. An object of the present invention is to provide a control device for an electric vehicle capable of minimizing a vehicle deceleration and a reduction effect on a regeneration amount.

In order to achieve the above object, in the control apparatus for an electric vehicle according to the present invention, a friction clutch by hydraulic engagement is interposed between the motor generator and the drive wheels, and when the braking request is made, the motor generator is set in a power generation mode, and the friction clutch And regenerative braking control means for applying a regenerative braking torque to the drive wheels.
When the regenerative braking control means detects that the friction clutch is slipping during regenerative braking control, the regenerative braking control means controls the rotational speed of the motor generator so as to reduce the differential rotation of the friction clutch, and After reducing the differential rotation of the clutch, the hydraulic pressure command value for the friction clutch is increased.

Therefore, in the electric vehicle control apparatus of the present invention, when the regenerative braking control means detects that the friction clutch is slipping during the regenerative braking control, the motor generator is configured to reduce the differential rotation of the friction clutch. The number of rotations is controlled. Then, after reducing the differential rotation of the friction clutch, the hydraulic pressure command value to the friction clutch is increased.
That is, during regenerative braking, when the amount of oil supplied to the friction clutch is temporarily insufficient and the friction clutch is in a slipping state due to a decrease in hydraulic pressure, it is necessary to wait until the hydraulic pressure is restored. When the engagement hydraulic pressure is restored and the engagement torque is generated, the sliding state of the friction clutch is converged and the engagement state is shifted to the engagement state. For this reason, for example, if the oil pressure command value is maintained, it takes a long time to shift to the engaged state because the friction clutch has a dynamic friction coefficient (<static friction coefficient) when the friction clutch is in a slipping state. On the other hand, when the hydraulic pressure command value is increased with the aim of shortening the time, the slip convergence timing and the clutch engagement timing are shifted, and a shock is generated due to fluctuations in the transmission torque.
On the other hand, using the waiting time until the working hydraulic pressure returns, the control that increases the hydraulic pressure command value after suppressing the slipping state of the friction clutch by the rotational speed control by the highly responsive motor generator is adopted. . For this reason, the shift from the preceding slip convergence control to the engagement control eliminates the shock caused by the slippage between the slip convergence and the clutch engagement. Further, when the operating oil pressure is restored, the friction clutch is shifted to the engaged state with good response by the oil pressure generated by the increase of the oil pressure command value and the static friction coefficient (or the value corresponding to the static friction coefficient).
As a result, when the friction clutch is in a slipping state during regenerative braking, the friction clutch is shifted to the engaged state at an early stage from the occurrence of slipping, thereby minimizing the impact on vehicle deceleration and regeneration amount. Can be suppressed.

  Hereinafter, the best mode for realizing a control device for an electric vehicle according to the present invention will be described based on a first embodiment shown in the drawings.

First, the configuration will be described.
FIG. 1 is an overall system diagram showing a rear-wheel drive FR hybrid vehicle (an example of an electric vehicle) to which the control device of the first embodiment is applied.

  As shown in FIG. 1, the drive system of the FR hybrid vehicle in the first embodiment includes an engine Eng, a flywheel FW, a first clutch CL1, a motor generator MG, a mechanical oil pump O / P, a second Clutch CL2 (friction clutch), automatic transmission AT, propeller shaft PS, differential DF, left drive shaft DSL, right drive shaft DSR, left rear wheel RL (drive wheel), right rear wheel RR ( Drive wheel). FL is the front left wheel, FR is the front right wheel, and M / O / P is the electric oil pump.

  The engine Eng is a gasoline engine or a diesel engine, and engine start control, engine stop control, and throttle valve opening control are performed based on an engine control command from the engine controller 1. The engine output shaft is provided with a flywheel FW.

  The first clutch CL1 is a clutch interposed between the engine Eng and the motor generator MG, and is generated by the first clutch hydraulic unit 6 based on a first clutch control command from the first clutch controller 5. The first clutch control hydraulic pressure controls engagement / release including the half-clutch state.

  The motor generator MG is a synchronous motor generator 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 the motor controller 2. It is controlled by doing. The motor generator 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 the rotor receives rotational energy from the engine Eng or driving wheels. , The battery 4 can 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 generator MG is connected to the transmission input shaft of the automatic transmission AT via a damper.

  The mechanical oil pump O / P is a pump that is operated by a rotational driving force from a transmission input shaft of the automatic transmission AT, and for example, a gear pump or a vane pump is used. In addition to the mechanical oil pump O / P, an electric oil pump M / O / P that operates on the rotational driving force of the motor is provided as the oil pump. The mechanical oil pump O / P and the electric oil pump M / O / P is used as a hydraulic pressure source for generating the engagement pressure to the second clutch CL2. This hydraulic power source stops the electric oil pump M / O / P when the amount of oil discharged from the mechanical oil pump O / P is sufficient, and the discharge oil pressure from the mechanical oil pump O / P When it decreases, the motor of the electric oil pump M / O / P is operated, and the operation oil is switched to discharge from the electric oil pump M / O / P.

  The second clutch CL2 is a clutch interposed between the motor generator MG and the left and right rear wheels RL, RR, and is controlled by the second clutch hydraulic unit 8 based on a second clutch control command from the AT controller 7. The generated and controlled hydraulic pressure controls the fastening and opening including slip fastening and slip opening. The first clutch hydraulic unit 6 and the second clutch hydraulic unit 8 are built in an AT hydraulic control valve unit CVU attached to the automatic transmission AT.

  The automatic transmission AT is, for example, a stepped transmission that automatically switches stepped speeds such as forward 7 speed / reverse speed 1 according to vehicle speed, accelerator opening, etc., and the second clutch CL2 However, it is not newly added as a dedicated clutch, but the most suitable clutch or brake arranged in the torque transmission path is selected from 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 the first clutch CL1, for example, a dry single-plate clutch whose engagement / release is controlled by a hydraulic actuator 14 having a piston 14a is used. As the second clutch CL2, for example, a wet multi-plate clutch or a wet multi-plate brake capable of continuously controlling the oil flow rate and hydraulic pressure with a proportional solenoid is used. The hybrid drive system has two modes, an electric vehicle travel mode (hereinafter referred to as “EV mode”) and a hybrid vehicle travel mode (hereinafter referred to as “HEV mode”), depending on the engaged / released state of the first clutch CL1. Has two driving modes. The “EV mode” is a mode in which the first clutch CL1 is released and the vehicle runs only with the power of the motor generator MG. The “HEV mode” is a mode in which the first clutch CL1 is engaged and the vehicle is driven by the power of the engine Eng and the motor generator MG.

Next, the control system of the hybrid vehicle will be described.
As shown in FIG. 1, the control system of the FR hybrid vehicle in 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. And an AT controller 7, a second clutch hydraulic unit 8, a brake controller 9, and an integrated controller 10. 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 mutually exchange information. ing.

  The engine controller 1 inputs engine speed information from the engine speed sensor 12, a target engine torque command from the integrated controller 10, and other necessary information. Then, a command for controlling the engine operating point (Ne, Te) is output to the throttle valve actuator or the like of the engine Eng.

  The motor controller 2 inputs information from the resolver 13 that detects the rotor rotational position of the motor generator MG, the target MG torque command and target MG rotation speed command from the integrated controller 10, and other necessary information. Then, a command for controlling the motor operating point (Nm, Tm) of motor generator MG is output to inverter 3. The motor controller 2 monitors the battery SOC indicating the charge capacity of the battery 4, and the battery SOC information is used for control information of the motor generator MG and is also connected to the integrated controller 10 via the CAN communication line 11. Supplied to.

  The first clutch controller 5 inputs sensor information from the first clutch stroke sensor 15 that detects the stroke position of the piston 14a of the hydraulic actuator 14, a target CL1 torque command from the integrated controller 10, and other necessary information. . Then, a command for controlling engagement / disengagement of the first clutch CL1 is output to the first clutch hydraulic unit 6 in the AT hydraulic control valve unit CVU.

  The AT controller 7 inputs information from an accelerator opening sensor 16, a vehicle speed sensor 17, and other sensors 18 (transmission input rotation speed sensor, inhibitor switch, etc.). Then, when driving with the D range selected, a control command for obtaining the searched gear position is searched for the optimum gear position based on the position where the operating point determined by the accelerator opening APO and the vehicle speed VSP exists on the shift map. Output to AT hydraulic control valve unit CVU. The shift map is a map in which an upshift line and a downshift line are written according to the accelerator opening and the vehicle speed. In addition to the above automatic shift control, when a target CL2 torque command is input from the integrated controller 10, a command for controlling engagement / release of the second clutch CL2 is output to the second clutch hydraulic unit 8 in the AT hydraulic control valve unit CVU. The second clutch control is performed.

  The brake controller 9 inputs a wheel speed sensor 19 for detecting the wheel speeds of the four wheels, sensor information from the brake stroke sensor 20, a regenerative cooperative control command from the integrated controller 10, and other necessary information. And, for example, at the time of brake depression, if the regenerative braking force is insufficient with respect to the required braking force required from the brake stroke BS, the shortage is compensated with mechanical braking force (hydraulic braking force or motor braking force) Regenerative cooperative brake control is performed.

  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 a motor rotational speed Nm, a discharge oil path from a hydraulic power source, and the like. Necessary information from the pump discharge pressure sensor 22, the second clutch input shaft rotational speed sensor 23, the second clutch output shaft rotational speed sensor 24, and other sensors and switches provided therein, and information via the CAN communication line 11 Enter. The target engine torque command to the engine controller 1, the target MG torque command and the target MG speed command to the motor controller 2, the target CL1 torque command to the first clutch controller 5, the target CL2 torque command to the AT controller 7, and the brake controller 9 Regenerative cooperative control command is output.

  FIG. 2 is a control block diagram illustrating arithmetic processing executed by the integrated controller 10 of the FR hybrid vehicle to which the control device of the first embodiment is applied. FIG. 3 is a diagram illustrating an EV-HEV selection map used when performing a mode selection process in the integrated controller 10 of the FR hybrid vehicle to which the control device of the first embodiment is applied. Hereinafter, based on FIG.2 and FIG.3, the arithmetic processing performed in the integrated controller 10 of Example 1 is demonstrated.

  As shown in FIG. 2, the integrated controller 10 includes a target driving force calculation unit 100, a mode selection unit 200, a target charge / discharge calculation unit 300, and an operating point command unit 400.

  The target driving force calculation unit 100 calculates a target driving force tFoO from the accelerator opening APO and the vehicle speed VSP using the target driving force map.

  The mode selection unit 200 uses the EV-HEV selection map shown in FIG. 3 to select “EV mode” or “HEV mode” as the target travel mode from the accelerator opening APO and the vehicle speed VSP. However, if the battery SOC is equal to or lower than the predetermined value, the “HEV mode” is forcibly set as the target travel mode.

  The target charge / discharge calculation unit 300 calculates a target charge / discharge power tP from the battery SOC using a target charge / discharge amount map.

  In the operating point command unit 400, based on input information such as the accelerator opening APO, the target driving force tFoO, the target travel mode, the vehicle speed VSP, the target charge / discharge power tP, etc., the target engine torque is set as the operating point reaching target. And target MG torque, target MG rotation speed, target CL1 torque, and target CL2 torque. Then, the target engine torque command, the target MG torque command, the target MG rotational speed command, the target CL1 torque command, and the target CL2 torque command are output to the controllers 1, 2, 5, and 7 via the CAN communication line 11.

  FIG. 4 is a flowchart showing the flow of regenerative braking control processing executed by the brake controller 9 of the FR hybrid vehicle to which the control device of the first embodiment is applied (regenerative braking control means). This flowchart is executed every predetermined processing cycle. Hereinafter, each step of FIG. 4 will be described.

  In step S1, it is determined whether or not the cooperative regenerative braking control for distributing the required braking torque to the frictional braking and the regenerative braking during the braking operation is in progress. If YES (cooperative regenerative), the process proceeds to step S2. If NO (except during cooperative regeneration), go to the end.

In step S2, following the determination that the cooperative regeneration is being performed in step S1, it is determined whether or not the slip state of the second clutch CL2 has been detected. If YES (when CL2 slip is detected), the process proceeds to step S3. If NO (when CL2 slip is not detected), the process proceeds to step S10.
Here, the slipping state of the second clutch CL2 includes the second clutch input shaft rotational speed from the second clutch input shaft rotational speed sensor 23 and the second clutch output shaft rotational speed from the second clutch output shaft rotational speed sensor 24. When the CL2 differential rotation is equal to or greater than a preset slip determination threshold, it is detected that the second clutch CL2 is in a slip state.

In step S3, following the determination that the CL2 slip is detected in step S2 or the determination that the CL2 differential rotation threshold is exceeded in step S5, the differential rotation of the second clutch CL2 is eliminated. The motor generator MG is controlled so as to return from the slipping state, and the process proceeds to step S4.
In the rotational speed control of the motor generator MG, the target input shaft rotational speed that is returned to the output shaft rotational speed in a short time is set with respect to the actual input shaft rotational speed that is decreased due to the slip of the second clutch CL2 (the rotational speed in FIG. 5). The actual MG torque of the motor generator MG is increased so that the actual input shaft speed matches the target input shaft speed (see MG torque characteristics in FIG. 5).

In step S4, following the MG rotation speed control in step S3, the braking force command value to the friction brake is increased so as to increase the amount of friction braking distributed by the friction brake, and the process proceeds to step S5.
Here, the braking force command value to the friction brake is a value obtained by subtracting the input torque to the second clutch CL2, the change in the rotation speed, and the estimated clutch torque estimated from the inertia from the required braking torque (FIG. 5). (See Target braking torque characteristics).

In step S5, following the increase in the amount of distribution to the friction brake in step S4, it is determined whether the input / output shaft differential rotation of the second clutch CL2 has converged within a preset CL2 differential rotation threshold, and YES If it is (within the CL2 differential rotation threshold), the process proceeds to step S6, and if NO (exceeds the CL2 differential rotation threshold), the process returns to step S3.
Here, the CL2 differential rotation threshold is set in consideration of the response delay time of the actual hydraulic pressure with respect to the hydraulic pressure command value of the second clutch CL2. That is, the timing at which the CL2 differential rotation converges to zero and the timing at which the actual hydraulic pressure of the second clutch CL2 rises to the hydraulic pressure command value are set to substantially coincide (the rotational speed characteristics and the CL2 hydraulic characteristics in FIG. reference).

  In step S6, following the determination that the pressure has converged within the CL2 differential rotation threshold value in step S5, or the determination that the hydraulic pressure of the hydraulic pressure source is less than a predetermined value in step S7, a hydraulic pressure command to the second clutch CL2 The value is increased to a value obtained by adding a safety component to the regenerative torque command value, and the process proceeds to step S7.

In step S7, following the increase in the CL2 hydraulic pressure command value in step S6, the hydraulic pressure from the hydraulic source switched to the electric oil pump M / O / P increases, and the hydraulic source hydraulic pressure (pump detected by the pump discharge pressure sensor 22) It is determined whether or not the discharge pressure is equal to or greater than a predetermined value. If YES (hydraulic pressure source pressure ≧ predetermined value), the process proceeds to step S8. If NO (hydraulic pressure source pressure <predetermined value), the process proceeds to step S6. Return.
Here, the predetermined value is set to a hydraulic pressure (hydraulic pressure corresponding to a hydraulic pressure command value) that can ensure the engagement of the second clutch CL2.

  In step S8, following the determination in step S7 that the hydraulic pressure is greater than or equal to the predetermined value, the motor generator MG is returned from the rotational speed control to the torque control (normal regeneration command), and the process proceeds to step S9.

In step S9, following the MG torque control in step S8, the increased hydraulic pressure command value for the second clutch CL2 is returned to a value corresponding to the regeneration target value, and the process proceeds to the end.
In step S9, at the same time, the command for increasing the distribution amount for the friction braking shared by the friction brake in step S4 is returned to the command for setting the distribution amount for the original friction braking.

  In step S10, following the determination that CL2 slip is not detected in step S2, normal cooperative regeneration control is continued, and the process proceeds to the end.

Next, the operation will be described.
First, the “problem of the comparative example when the friction clutch is in a slip state during the regenerative braking control” will be described, and then the operation of the control device for the FR hybrid vehicle of the first embodiment will be described as “during regenerative braking control. "Regenerative braking control action when the friction clutch is in a slipping state", "Distribution amount increasing action to friction brake by cooperative regenerative braking control", "Hydraulic command value increase control action in regenerative braking control of Embodiment 1" The description will be divided into “return control action”.

[Problems of the comparative example when the friction clutch slips during regenerative braking control]
For example, in the case of an engine vehicle, since the engine is driven at the idling speed even when the vehicle is stopped, the hydraulic pressure discharged from the mechanical oil pump that is operated by the rotational force of the drive system is secured, and the driving torque and braking torque are reduced. It is possible to maintain the engaged state of the friction clutch by hydraulic engagement provided in the transmission path.

  However, in the case of an electric vehicle (hybrid vehicle, electric vehicle, etc.), when the vehicle decelerates, the driving motor is decelerated according to the deceleration, and when the vehicle stops, the driving motor is also stopped. The amount of oil discharged from a mechanical oil pump that operates by force is insufficient. Therefore, in the case of an electric vehicle, an electric oil pump is provided in addition to the mechanical oil pump, and when the discharge hydraulic pressure from the mechanical oil pump decreases, the hydraulic pressure source is switched to the hydraulic oil discharge from the electric oil pump. It is said.

  Thus, in the system of the comparative example in which the mechanical oil pump and the electric oil pump are switched as the hydraulic source, if the amount of oil discharged from the mechanical oil pump is insufficient during regenerative braking during vehicle deceleration, the mechanical type Although the oil pump is switched to the electric oil pump, there is a case where the engagement hydraulic pressure to the friction clutch is lowered during the transition period and the friction clutch is in a slipping state. When the friction clutch slips during the regenerative braking, it is necessary to wait at least until the hydraulic pressure is restored. When the operating hydraulic pressure is restored and the engagement torque is generated, the friction clutch is re-engaged.

  For this reason, for example, if the hydraulic pressure command value is maintained, after waiting for the hydraulic pressure to return, the hydraulic clutch shifts to the engaged state while converging the sliding state of the friction clutch by the hydraulic pressure. In addition, when the friction clutch is in a slipping state, a dynamic friction coefficient (<static friction coefficient) is required, and thus it takes a long time for the friction clutch to shift to an engaged state. As a result, the state in which the vehicle deceleration continues during regenerative braking continues, causing the driver and other passengers to feel uncomfortable, and the desired amount of regeneration cannot be secured. In particular, in the case of a hybrid vehicle in which an engine and a motor generator are mounted together, a reduction in the regeneration amount directly leads to a reduction in fuel consumption of the engine.

  On the other hand, for example, when the hydraulic pressure command value is increased with the aim of shortening the time, the friction clutch is immediately shifted to the engaged state by the high hydraulic pressure after waiting until the hydraulic pressure is restored. In other words, the friction clutch is engaged before the slip state of the friction clutch is converged, and the slip convergence timing and the clutch engagement timing are deviated, and the transmission torque fluctuates, so that the vehicle moves back and forth during regenerative braking. A shock that is shaken occurs.

[Regenerative braking control action when friction clutch slips during regenerative braking control]
FIG. 5 shows target braking torque, rotational speed, MG torque, CL2 hydraulic pressure, and MG control when the second clutch CL2 is in a slipping state during vehicle deceleration by cooperative regenerative braking in the FR hybrid vehicle of the first embodiment. It is a time chart which shows a characteristic. Hereinafter, the regenerative braking control operation when the clutch hydraulic pressure is insufficient will be described with reference to FIGS. 4 and 5.

  At the time of deceleration by depressing the brake pedal, regenerative braking is being executed in cooperation, but when slippage of the second clutch CL2 is not detected, the flow proceeds from step S1 to step S2 to step S10 to end in the flowchart shown in FIG. Is repeated. In other words, normal cooperative regenerative braking that distributes the required braking torque that appears in the amount of brake pedal depression by the friction braking that is shared by the friction brakes provided on each wheel and the regenerative braking that is shared by the power generation of the motor generator MG. Execute control.

  If slippage of the second clutch CL2 is detected during execution of regenerative braking by this cooperation, in the flowchart shown in FIG. 4, the process proceeds from step S1, step S2, step S3, step S4, step S5, and step S5. As long as the differential rotation convergence condition for the second clutch CL2 is not satisfied, the flow from step S3 to step S4 to step S5 is repeated. That is, in step S3, the rotational speed of motor generator MG is controlled so as to eliminate the differential rotation of second clutch CL2. In step S4, the braking force command value to the friction brake is increased so as to increase the amount of friction braking distributed by the friction brake.

  When the differential rotation convergence condition for the second clutch CL2 in step S5 is satisfied, in the flowchart shown in FIG. 4, the process proceeds from step S5 to step S6 to step S7, and unless the hydraulic pressure source hydraulic pressure condition in step S7 is satisfied. The flow from step S6 to step S7 is repeated. That is, in step S6, the hydraulic pressure command value for the second clutch CL2 is increased to a value obtained by adding a safety component to the regenerative torque command value.

  Then, when the hydraulic pressure source hydraulic pressure condition is established in step S7, the process proceeds from step S7 to step S8 → step S9 → end in the flowchart shown in FIG. That is, in step S8, the control of motor generator MG is returned from the rotational speed control to the torque control. In step S9, the increased hydraulic pressure command value for the second clutch CL2 is returned to a value corresponding to the regenerative target value, and the distribution amount of the increased friction braking portion shared by the friction brake is set to the original friction braking amount. The command is returned to the distribution amount.

  When the slip of the second clutch CL2 converges and the slip of the second clutch CL2 is no longer detected, the flow shown in FIG. 4 is repeated from step S1, step S2, step S10, and the end. Normal cooperative regenerative braking control is executed.

  As described above, in the first embodiment, during regenerative braking control, the second clutch CL2 is in a slipping state at time t1 in FIG. 5 as the hydraulic power source is switched to the electric oil pump M / O / P. Is detected, the rotational speed control of the motor generator MG is started so as to reduce the differential rotation of the second clutch CL2, and the control for increasing the distribution amount of the friction braking shared by the friction brake is performed. Be started.

  When it is determined at time t2 in FIG. 5 that the input / output shaft differential rotation of the second clutch CL2 has converged within a preset CL2 differential rotation threshold, the hydraulic pressure command value to the second clutch CL2 is The regenerative torque command value is increased to a value obtained by adding a safety component.

  Then, at time t3 in FIG. 5, when it is determined that the hydraulic pressure is higher than a predetermined value, that is, the hydraulic pressure that can secure the engagement of the second clutch CL2 is determined, the control of the motor generator MG is returned to the torque control. Then, the hydraulic pressure command value for the second clutch CL2 is returned to a value corresponding to the regeneration target value, and the command for the friction brake is returned to the command that uses the distribution amount for the original friction braking.

  As described above, the first embodiment employs the control in which the hydraulic pressure command value to the second clutch CL2 is increased after the slip state of the second clutch CL2 is suppressed by the rotational speed control by the motor generator MG. For this reason, it is possible to suppress the slipping state of the second clutch CL2 by utilizing the waiting time until the hydraulic pressure is restored and performing the rotational speed control by the motor generator MG having high responsiveness. Therefore, a shock caused by a slippage between the slip convergence timing and the clutch engagement timing as in the case of simply increasing the hydraulic pressure command value is eliminated. Further, when the operating oil pressure is restored, the second clutch CL2 is shifted to the engaged state with good response due to the oil pressure generated by the increase of the oil pressure command value and the static friction coefficient (or the value corresponding to the static friction coefficient). Thus, the slip convergence control and the engagement control are separated, and the slip convergence control side is left to the second clutch CL2 by entrusting the rotational speed control by the motor generator MG that has high responsiveness and is irrelevant to the presence or absence of hydraulic pressure. The time required to return from the slip state to the fastening state can be greatly reduced as compared with the comparative example. As a result, when the second clutch CL2 is in a slipping state during regenerative braking, it is possible to minimize the influence on the vehicle deceleration and the regenerative amount.

[Distribution increase to friction brake by cooperative regenerative braking control]
The first embodiment performs cooperative regenerative braking control in which the required braking torque is distributed between the friction braking and the regenerative braking during the braking operation. Then, as shown in the target braking torque characteristic of FIG. 5, the distribution of the frictional braking is performed so as to maintain the required braking torque from time t1 to time t3 when the second clutch CL2 is in a slipping state and the regenerative braking amount decreases. Increase.
That is, even when the second clutch CL2 is slipping, the estimated clutch torque due to the slip engagement is transmitted to the left and right rear wheels RL and RR via the second clutch CL2, and is shown in the target braking torque characteristics of FIG. Thus, the effect | action which maintains a request | requirement braking torque by compensating the reduction | decrease part for regenerative braking is shown.
Therefore, even if the regenerative braking amount decreases due to the slippage of the second clutch CL2, the required braking torque is maintained even while the second clutch CL2 is slipping by compensating the decrease amount by increasing the distribution of the friction braking amount. As a result, stable braking performance with a constant vehicle deceleration can be ensured.

[Hydraulic Command Value Increase Control Action and Return Control Action in Regenerative Braking Control of Embodiment 1]
In the regenerative braking control of the first embodiment, when the differential rotation of the second clutch CL2 converges within the threshold value by the rotation speed control of the motor generator MG, the increase of the hydraulic pressure command value to the second clutch CL2 is started.
That is, since the hydraulic response of the second clutch CL2 is inferior to the control response of the motor generator MG, it is confirmed that the hydraulic power source has returned to the state just before the slip detection, and the hydraulic command value to the second clutch CL2 is increased. Is started, the second clutch CL2 may slip again after the motor generator MG is returned to the torque control.
On the other hand, in the first embodiment, the second clutch CL2 is restarted after the motor generator MG is returned to the torque control by starting to increase the hydraulic pressure command value to the second clutch CL2 before the hydraulic pressure source is restored. It can prevent slipping.

In the regenerative braking control of the first embodiment, the hydraulic pressure command value for the first clutch CL1 is set to a value larger than the regenerative braking torque command value.
That is, since the hydraulic response of the second clutch CL2 is inferior, when the hydraulic pressure command value for the second clutch CL2 is increased to the regenerative braking torque command value, the actual hydraulic pressure of the second clutch CL2 rises to the regenerative braking torque command value level. Will be delayed.
In contrast, in the first embodiment, the second clutch CL2 is more responsive than by increasing the hydraulic pressure command value for the first clutch CL1 to a value larger than the regenerative braking torque command value. Can be shifted to the fastening state.

  Then, at the timing when the differential rotation of the second clutch CL2 converges within the threshold value, the increase of the hydraulic pressure command value to the second clutch CL2 is started, and the hydraulic pressure command value is increased to a value larger than the regenerative braking torque command value. By doing so, it becomes possible to shift the second clutch CL2 to the engaged state at the timing when the hydraulic power source returns. That is, in FIG. 5, the time required to complete the transition of the second clutch CL2 in the slipping state from time t1 to time t3 to the engaged state can be made substantially equal to the time required for the hydraulic pressure of the hydraulic power source to return. it can.

The second clutch CL2 of the first embodiment has a hydraulic pressure source that switches to hydraulic oil discharge from the electric oil pump M / O / P when the discharge hydraulic pressure from the mechanical oil pump O / P that operates by the driving system rotational force decreases. In the regenerative braking control, when the discharge hydraulic pressure from the hydraulic pressure source is secured while the hydraulic pressure command value to the second clutch CL2 is being increased, the motor generator MG is returned from the rotational speed control to the torque control, The hydraulic pressure command value for the two-clutch CL2 is returned to a value corresponding to the regeneration target value.
That is, if the hydraulic pressure command value to the second clutch CL2 is kept increased even if the discharge hydraulic pressure from the hydraulic pressure source is secured, a wasteful discharge amount is generated from the electric oil pump M / O / P. Further, in the next engine start control, shift control, etc., when shifting to the control for slipping the second clutch CL2, the slip control is performed by reducing the engagement pressure from the high pressure side, and it takes time to shift to the slip control. .
In contrast, in the first embodiment, when the discharge hydraulic pressure from the hydraulic source is ensured, the hydraulic oil command value is returned to a value corresponding to the regeneration amount (a value corresponding to the transmission torque), so that the electric oil pump M / O Useless discharge from / P can be suppressed. In addition, by returning the engagement torque of the second clutch CL2 to a torque corresponding to the regeneration amount, the control can smoothly shift to the slip control when the control shifts to the slip control of the second clutch CL2.

Next, the effect will be described.
In the control device for the FR hybrid vehicle of the first embodiment, the effects listed below can be obtained.

  (1) A friction clutch (second clutch CL2) by hydraulic engagement is interposed between the motor generator MG and the driving wheels (left and right rear wheels RL, RR). When a braking request is made, the motor generator MG is set to a power generation mode. In the control device for an electric vehicle (FR hybrid vehicle) provided with regenerative braking control means for applying regenerative braking torque to the drive wheels (left and right rear wheels RL, RR) after passing through the friction clutch (second clutch CL2), When the regenerative braking control means (FIG. 4) detects that the friction clutch (second clutch CL2) is slipping during regenerative braking control, the regenerative braking control means (FIG. 4) reduces the differential rotation of the friction clutch (second clutch CL2). Then, after the rotational speed of the motor generator MG is controlled to reduce the differential rotation of the friction clutch (second clutch CL2), the hydraulic pressure command value to the friction clutch (second clutch CL2) is increased. For this reason, when the friction clutch (second clutch CL2) is in a slipping state during regenerative braking, the friction clutch (second clutch CL2) is shifted to the engaged state without shock and at an early stage after the occurrence of slipping. The impact on the vehicle deceleration and the amount of regeneration can be minimized.

  (2) The regenerative braking control means (FIG. 4) is means for performing cooperative regenerative braking control that distributes the required braking torque to the friction braking amount and the regenerative braking amount during a braking operation, and the friction clutch (second clutch CL2). ) Increases the distribution of the friction braking amount so as to maintain the required braking torque while the regenerative braking amount decreases in the slip state. For this reason, the required braking torque is maintained even while the friction clutch (second clutch CL2) is slipping, and stable braking performance by a constant vehicle deceleration can be ensured.

  (3) The regenerative braking control means (FIG. 4), when the differential rotation of the friction clutch (second clutch CL2) converges within a threshold by controlling the rotational speed of the motor generator MG, the friction clutch (second clutch CL2). The oil pressure command value increases to). For this reason, an increase in the hydraulic pressure command value to the second clutch CL2 is started before the hydraulic pressure source is restored, and the second clutch CL2 slips again after the motor generator MG is returned to the torque control. Can be prevented.

  (4) The regenerative braking control means (FIG. 4) sets the hydraulic pressure command value to the friction clutch (second clutch CL2) to a value larger than the regenerative braking torque command value. For this reason, compared with the case where it increases to regenerative braking torque command value, the 2nd clutch CL2 can be changed to an engagement state with sufficient response.

  (5) The friction clutch (second clutch CL2) switches to hydraulic oil discharge from the electric oil pump M / O / P when the discharge hydraulic pressure from the mechanical oil pump O / P operated by the drive system rotational force decreases. The regenerative braking control means (FIG. 4) has a hydraulic pressure source, and when the discharge hydraulic pressure from the hydraulic pressure source is secured while increasing the hydraulic pressure command value to the friction clutch (second clutch CL2), The motor generator MG is returned from the rotational speed control to the torque control, and the hydraulic pressure command value to the friction clutch (second clutch CL2) is returned to a value corresponding to the regeneration target value. For this reason, wasteful discharge from the electric oil pump M / O / P can be suppressed, and thereafter, when the control is shifted to the control of slipping the second clutch CL2, the control can smoothly shift to the slip control.

  As mentioned above, although the control apparatus of the electric vehicle of this invention was demonstrated based on Example 1, it is not restricted to this Example 1 about a concrete structure, The invention which concerns on each claim of a claim Design changes and additions are permitted without departing from the gist of the present invention.

  In Example 1, the example of the regenerative braking control by cooperation of a friction brake and a regenerative brake was shown. However, for example, the cooperative regenerative braking control may not be performed, and the vehicle may be decelerated only by the regenerative brake when the deceleration is requested.

  In the first embodiment, an example in which a hydraulic oil source includes a mechanical oil pump and an electric oil pump is illustrated, and the friction clutch is in a slipping state by pump switching. However, the present invention can also be applied to an example in which one oil pump is provided as a hydraulic pressure source and the hydraulic pressure temporarily decreases due to some cause during regenerative braking.

  In the first embodiment, the application example to the FR hybrid vehicle is shown, but the present invention can also be applied to other electric vehicles such as an FF hybrid vehicle, an electric vehicle, and a fuel cell vehicle. In Example 1, the example which uses the friction engaging element (2nd clutch) built in the automatic transmission as a friction clutch was shown. However, a friction clutch may be provided independently at an upstream position or a downstream position of the automatic transmission. Further, the present invention can be applied to a system that does not have an automatic transmission and includes only a friction clutch between a motor generator and a drive wheel. In short, the present invention can be applied to any electric vehicle in which a friction clutch by hydraulic engagement is interposed between the motor generator and the drive wheels.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an overall system diagram showing a rear-wheel drive FR hybrid vehicle (an example of an electric vehicle) to which a control device according to a first embodiment is applied. It is a control block diagram which shows the arithmetic processing performed in the integrated controller 10 of the FR hybrid vehicle to which the control apparatus of Example 1 was applied. It is a figure which shows the EV-HEV selection map used when performing the mode selection process in the integrated controller 10 of the FR hybrid vehicle to which the control apparatus of Example 1 is applied. It is a flowchart which shows the flow of the regenerative braking control process performed in the brake controller 9 of FR hybrid vehicle to which the control apparatus of Example 1 was applied. Time indicating characteristics of target braking torque, rotation speed, MG torque, CL2 hydraulic pressure, and MG control when the second clutch CL2 is in a slipping state during vehicle deceleration by cooperative regenerative braking in the FR hybrid vehicle of the first embodiment. It is a chart.

Explanation of symbols

Eng engine
FW flywheel
CL1 1st clutch
MG motor generator
O / P mechanical oil pump (hydraulic power source)
M / O / P Electric oil pump (hydraulic power source)
CL2 2nd clutch (friction clutch)
AT automatic transmission
PS propeller shaft
DF differential
DSL left drive shaft
DSR right drive shaft
RL Left rear wheel (drive wheel)
RR Right rear wheel (drive wheel)
DESCRIPTION OF SYMBOLS 1 Engine controller 2 Motor controller 3 Inverter 4 Battery 5 1st clutch controller 6 1st clutch hydraulic unit 7 AT controller 8 2nd clutch hydraulic unit 9 Brake controller 10 Integrated controller 11 CAN communication line 12 Engine speed sensor 13 Resolver 14 Hydraulic actuator 14a piston 15 first clutch stroke sensor 16 accelerator opening sensor 17 vehicle speed sensor 18 inhibitor switch 19 wheel speed sensor 20 brake switch sensor 21 motor rotation speed sensor 22 pump discharge pressure sensor 23 second clutch input shaft rotation speed sensor 24 second clutch Output shaft speed sensor

Claims (5)

A regenerative braking control in which a friction clutch by hydraulic engagement is interposed between the motor generator and the drive wheel, and when the brake is requested, the motor generator is set in a power generation mode, and the regenerative braking torque is applied to the drive wheel after the friction clutch has passed. In a control device for an electric vehicle comprising means,
When the regenerative braking control means detects that the friction clutch is slipping during regenerative braking control, the regenerative braking control means controls the rotational speed of the motor generator so as to reduce the differential rotation of the friction clutch, and A control apparatus for an electric vehicle characterized by increasing a hydraulic pressure command value to the friction clutch after reducing the differential rotation. In the control apparatus of the electric vehicle according to claim 1,
The regenerative braking control means is a means for performing cooperative regenerative braking control that distributes the required braking torque to the friction braking amount and the regenerative braking amount during a braking operation, and while the friction clutch is in a slipping state, the regenerative braking amount decreases. A control device for an electric vehicle, characterized by increasing a distribution of friction braking so as to maintain a required braking torque. In the control apparatus for the electric vehicle according to claim 1 or 2,
The regenerative braking control means starts to increase the hydraulic pressure command value to the friction clutch when the differential rotation of the friction clutch converges within a threshold value by the rotation speed control of the motor generator. apparatus. In the control apparatus of the electric vehicle described in any one of Claim 1- Claim 3,
The regenerative braking control means sets the hydraulic pressure command value to the friction clutch to a value larger than the regenerative braking torque command value. In the control apparatus of the electric vehicle described in any one of Claim 1 to Claim 4,
The friction clutch has a hydraulic pressure source that switches to hydraulic oil discharge from the electric oil pump when the discharge hydraulic pressure from the mechanical oil pump that is operated by the driving system rotational force decreases,
When the discharge hydraulic pressure from the hydraulic pressure source is ensured while increasing the hydraulic pressure command value to the friction clutch, the regenerative braking control means returns the motor generator from the rotational speed control to the torque control, and A control apparatus for an electric vehicle, wherein a hydraulic pressure command value for a clutch is returned to a value corresponding to a regeneration target value.

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