JP2005143183A - Driver for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a driver for a vehicle having a motor as a drive source in which the response time is not affected by the operating conditions of the motor but has a desired value when clutching request is issued. <P>SOLUTION: A rear unit 40 for driving rear wheels 20L and 20R includes a rear motor 90 and a clutch 95. An ECU 60 issues clutching request based on the operating conditions being detected based on the outputs from various sensors. When clutching request is issued, the ECU 60 calculates the target r.p.m. of the rear motor corresponding to the estimated wheel speed after elapsing a desired clutching request time. The rear motor 90 is controlled by the ECU 60 and a PCU 70 such that the actual r.p.m. reaches the target r.p.m. after elapsing the clutching request time. The clutch 95 is actuated based on a designation from the ECU 60 after elapsing the clutching request time. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a vehicle drive device, and more particularly, to a vehicle drive device that drives an axle via a clutch by an electric motor (motor).

  Recently, hybrid vehicles (electric vehicles) and electric vehicles (electric vehicles) in which an electric motor (motor) is incorporated in a drive device have attracted a great deal of attention as environmentally friendly vehicles. Some hybrid vehicles have been put into practical use.

  In some types of hybrid vehicles, a configuration of a drive device that drives an axle through a clutch by a motor is used. In such a configuration, it is required to suppress a torque shock that occurs when driving by a motor is added or when switching to driving force by a motor.

  For this reason, a control method is disclosed in which a wheel-side rotation speed detection mechanism is provided, and when the clutch is engaged, the motor is idled until the motor rotation speed becomes equal to or higher than the wheel-side rotation speed, and then the clutch is engaged ( For example, Patent Document 1).

In addition, when a drive command, that is, a clutch engagement request is output, the time required until the motor rotational speed becomes equal to the axle speed is calculated from a prediction equation for predicting subsequent changes in the axle speed and the motor speed rise characteristics. A control method is also disclosed in which the clutch is engaged after the required time has elapsed (for example, Patent Document 2).
JP 2003-97600 A JP-A-11-243608

  However, in the clutch engagement control systems disclosed in Patent Documents 1 and 2, the response time from when a clutch engagement request is made until the clutch engagement is actually completed depends on the response characteristics of the motor speed.

  Considering that the response characteristics of the motor speed change due to the motor temperature, output torque, etc., in the above clutch engagement control method, the dominant factor that determines the response time at the time of clutch engagement is not the driving situation but the motor condition. It becomes an operating condition. On the other hand, since the response time at the time of clutch engagement desirable for operation varies depending on the driving situation, the vehicle drive device by the conventional clutch engagement control system cannot run as intended by the driver. Therefore, there is a concern that drivability will deteriorate.

  The present invention has been made to solve such problems, and an object of the present invention is to provide a motor for a vehicle having a motor that is engaged by a clutch as a drive source. The response time until the clutch is engaged is set to a desired value regardless of the operating conditions.

  The vehicle drive device according to the present invention includes an electric motor, a clutch, and a control device. The electric motor can drive the wheels. The clutch is disposed between the wheel driven by the electric motor and the electric motor. The control device is provided to control driving of the vehicle. The control device calculates the target rotational speed of the motor corresponding to the estimated wheel speed after the elapse of a desired clutch engagement request time when a clutch engagement request is made, and further, after the clutch engagement request time elapses, The motor is controlled such that the number of rotations reaches the target number of rotations, and the clutch is engaged between the motor and the wheels after the clutch engagement request time has elapsed based on an instruction from the control device.

  Preferably, the clutch engagement request time is determined according to the driving situation.

  Preferably, the vehicle drive device further includes a wheel drive source other than the electric motor.

  More preferably, the clutch engagement request is issued according to the driving situation while the vehicle is traveling.

  Preferably, the control device calculates the estimated wheel speed and the target rotational speed based on the detected value of the rotational speed of the wheel and the calculated value of the driving force of the wheel when the clutch is requested to be engaged.

  Alternatively, preferably, the control device corrects the target rotational speed calculated corresponding to the estimated wheel speed in accordance with the actual rotational speed of the motor, the clutch engagement request time, and the predicted response time of the motor to control the motor. By doing so, a control system is configured in which the response characteristic of the actual rotational speed of the electric motor with respect to the target rotational speed depends on the clutch engagement request time.

  More preferably, the target rotational speed calculated corresponding to the estimated wheel speed is MVr, the corrected target rotational speed is MVr #, the predicted response time of the motor is Tmt, and the clutch engagement request time constant based on the clutch engagement request time is set. Trqc, where MV is the actual number of revolutions of the motor, MVr # = (Tmt / Trqc) · MVr− (Tmt / Trqc−1) · MV Is controlled.

  Preferably, the predicted response time of the electric motor is obtained according to the operating condition of the electric motor, and the operating condition includes at least one of the temperature, the current, and the rotational speed of the electric motor.

  The vehicle drive device according to the present invention actually engages the clutch after controlling the electric motor to reach the target rotational speed corresponding to the estimated wheel speed when a desired clutch engagement request time has elapsed. Therefore, the response time until clutch engagement can be set to a desired clutch engagement request time that does not depend on the operating conditions of the electric motor.

  In particular, by determining the clutch engagement request time according to the driving situation, the response time until the clutch is engaged can be set according to the driving situation, not depending on the operating conditions of the motor, so that the drivability is improved. Can do.

  Further, by providing a vehicle drive source in addition to the electric motor, it is possible to suppress the torque shock while engaging the clutch while the vehicle is running and to add a wheel drive torque by the electric motor.

  Further, the motor is controlled by correcting the target rotational speed corresponding to the estimated wheel speed when the clutch engagement request time has elapsed in accordance with the actual motor rotational speed, the clutch engagement request time, and the predicted response time of the motor. Thus, control is performed so that the response characteristic with the motor target rotation speed as input and the motor rotation speed (actual value) as output depends on the clutch engagement request time. As a result, it is possible to engage the clutch while suppressing the torque shock when the clutch engagement request time has elapsed without being influenced by the operating conditions of the electric motor.

  In particular, by obtaining the predicted response time of the motor according to the operating condition of the motor including at least one of the temperature, current and rotational speed of the motor, the actual response time of the motor can be tracked, Estimated response time can be defined. As a result, the motor speed control after the clutch engagement request can be made highly accurate.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, about the same or equivalent part in a figure, the same code | symbol is attached | subjected and the description is not repeated.
[Embodiment 1]
FIG. 1 is a block diagram illustrating a configuration of an automobile provided with an electric drive device for a vehicle according to the present invention.

  Referring to FIG. 1, an automobile 100 according to the present invention includes front wheels 10L and 10R, rear wheels 20L and 20R, a front drive unit 30 for driving front wheels, a rear drive unit 40 for driving rear wheels, and an engine 50. An ECU (Electrical Control Unit) 60, a PCU (Power Control Unit) 70, and a battery 80.

  The rear drive unit 40 includes a rear motor 90 that is an electric motor for driving the rear wheels 20L and 20R, and a clutch 95. Clutch 95 is provided between rear motor 90 and the axle connected to rear wheels 20L and 20R.

  When the clutch 95 is engaged, the torque generated by the rear motor 90 is transmitted to the axle, and the rear wheels 20L and 20R can be driven. Further, when the rear motor 90 is rotated by the rear wheels 20L and 20R during deceleration or the like, the rear motor 90 operates as a generator.

  The engine 50 is used to drive the front wheels 10L and 10R. The front drive unit 30 incorporates a front drive motor (not shown), and drives the front wheels 10L and 10R by torque generated by the engine 50 and / or the front drive motor. The front drive motor can also be operated as a generator when rotated by the front wheels 10L, 10R or the engine 50.

  The ECU 60 provided as the “control device” is input with information indicating the driving situation / vehicle situation from various sensors including the accelerator depression amount / depression speed detected by the position sensor disposed on the accelerator pedal 15. . In addition to the output of the accelerator position sensor described above, the information indicating the driving situation includes a wheel speed sensor output and a vehicle body gradient sensor output particularly in connection with the present embodiment. Furthermore, the temperature sensor, current sensor, rotational speed sensor output, etc. of the rear motor 90 indicating the motor operating conditions are input as the vehicle status. ECU 60 performs various controls related to automobile 100 in an integrated manner based on the input information.

  The PCU 70 generally indicates power converters required in the automobile 100. That is, the PCU 70 includes an inverter (not shown) that converts DC power into AC power, a DC-DC converter (not shown) that converts the voltage level of the DC voltage, and the like. In particular, this inverter converts DC power supplied from the battery 80 into AC power for driving the motor, and when the generator (motor) is driven by the engine 50, or during regenerative braking operation of the motor itself. The AC voltage generated in the step is converted into a DC voltage for charging the battery 80. The DC-DC converter is mainly used for converting a DC voltage to a level suitable for a power supply voltage for an auxiliary machine such as an air conditioner.

  Between the battery 80, the front drive unit 30 and the rear drive unit 40, and the PCU 70, power supply cables 81, 82, and 83 are respectively disposed to transmit electric power.

  In the present embodiment, traveling of automobile 100 is basically performed by driving front wheels 10L, 10R (FF mode) by front drive unit 30. However, at the time of starting, sudden acceleration, and low friction coefficient road travel (hereinafter referred to as “low μ travel”), four-wheel drive travel (4WD mode) is performed to achieve stable drive torque distribution. .

  In the 4WD mode, the clutch engagement request flag is turned on in the ECU 60, and in response to this, the clutch 95 is engaged to transmit the output torque of the rear motor 90 to the axles of the rear wheels 20L and 20R, and the front wheels 10L and 10R. In addition, the rear wheels 20L and 20R are driven. Further, also during deceleration and braking, by engaging the clutch 95, the rear motor 90 can be operated as a generator, and the energy for charging the battery 80 can be recovered.

  When the clutch 95 is engaged during traveling, that is, with the rear wheels 20L and 20R rotating, the speed (number of rotations) of the rear motor 90 and the speed of the rear wheels 20L and 20R are synchronized when the clutch is engaged. Need to be. In the present embodiment, the response time until the clutch is engaged when a clutch 95 engagement request is generated is set to a desired clutch engagement request time regardless of the motor operating conditions by the clutch engagement control system described below. Control.

  FIG. 2 is a flowchart illustrating a clutch engagement control method according to the embodiment of the present invention. The flowchart in FIG. 2 shows the operation of the ECU 60.

  Referring to FIG. 2, based on various sensor outputs input to ECU 60, the clutch engagement request flag is turned on ("1") and a clutch engagement request is generated (step S100). For example, when “accelerated acceleration” is recognized from the accelerator depressing amount and the depressing speed, “low μ travel” is recognized by slip detection from a sudden change in wheel rotation speed, or during deceleration / braking, etc. Then, the clutch engagement request flag is turned on (“1”).

  First, the ECU 60 determines the clutch engagement request time Trq from the operation state when the clutch engagement request is generated, and also determines the motor predicted response time Tmt from the motor conditions (step S110). For example, when “rapid acceleration” or “low μ travel” as described above is recognized as the driving situation, the clutch engagement request time Trq is set relatively short, and in other cases, it is set relatively long. Is done.

  Specifically, as shown in FIG. 3, a desired clutch engagement request time Trq is pre-assigned according to parameters such as accelerator depression amount / depression speed, vehicle speed, gradient sensor output, slip detection presence / absence indicating the driving situation. By creating the map 110 in the ECU 60 and referring to the map 110 when a clutch engagement request is generated, a desired clutch engagement request time Trq according to the driving situation can be determined.

  Similarly, as the motor conditions, based on data obtained in advance through experiments or the like according to at least one of the motor temperature, the motor rotation speed, the motor current, or the like, which is a variation factor of the equivalent circuit constant of the motor, A predicted motor response time Tmt is set.

  For example, by measuring the step response in the speed control system (closed loop system) of the rear motor 90, the motor speed control system can be modeled by the first-order lag system 1 / (Tmt # · s + 1). Accordingly, the step response is measured in advance for each motor condition, and a map 115 based on the measured motor response time (time constant) Tmt # is created in the ECU 60. In addition, by referring to the map 115 when the clutch engagement request is generated, the predicted motor response time (time constant) Tmt can be determined by following the change in the response characteristics of the motor according to the motor conditions.

  The maps 110 and 115 shown in FIG. 3 may be a multidimensional map with a plurality of input parameters, or a map may be created for each parameter. When a plurality of maps are created, the clutch engagement request time Trq and the predicted motor response time Tmt are determined from the values obtained from the maps according to predetermined conditions (maximum value / minimum value / average value, etc.). To do.

  Once the desired clutch engagement request time Trq is determined, the estimated wheel speed after the clutch engagement request time Trq has elapsed from the generation of the clutch engagement request and the motor target rotational speed MVr corresponding thereto are calculated (step). S120). For example, as in Patent Document 2, the estimated wheel speed is calculated by preparing in advance a prediction equation based on the wheel speed (actual value) at the time of clutch engagement request and the vehicle driving force (calculated value). Can do.

  In the present invention, in actual motor speed (rotational speed) control, the motor target rotational speed is corrected according to the actual value MV of the motor rotational speed, the predicted motor response time Tmt, and the clutch engagement request time Trq (step S130). .

  Using the motor target rotation speed MVr # thus corrected, the speed of the rear motor 90 is controlled so that the motor rotation speed after the clutch engagement request time Trq has elapsed matches the original motor target rotation speed MVr ( Step S140).

  FIG. 4 is a block diagram showing a motor speed (rotation speed) control method according to this embodiment.

  Referring to FIG. 4, the motor speed control system 150 according to this embodiment includes an original motor speed control system 160, a motor target rotation number calculation unit 170, and a motor target rotation number correction unit 180.

  The motor speed control system 160 corresponds to a closed loop control system that performs control based on a known PWM control method or the like so that the actual rotational speed (speed) MV of the rear motor 90 matches the target rotational speed (speed) MVr #. As already described, the motor speed control system 160 is approximated by a first-order lag system whose time constant changes according to the motor condition: 1 / (Tmt # · s + 1).

  The motor target rotational speed calculation unit 170 executes a process corresponding to step S120. That is, the motor target rotation speed calculation unit 170 determines the estimated wheel speed after the clutch engagement request time Trq has elapsed from the clutch engagement request according to the input wheel speed (actual value) WV and vehicle driving force (calculated value) DF. Further, the motor target rotational speed MVr corresponding to this is calculated.

  The motor target rotation speed correction unit 180 corrects the motor target rotation speed according to the following equation (1) using the predicted motor response time Tmt and the clutch engagement request time constant Trqc.

MVr # = (Tmt / Trqc) .MVr- (Tmt / Trqc-1) .MV (1)
Here, the clutch engagement request time constant Trqc is determined to be, for example, Trqc = Trq / 4 based on the clutch engagement request time Trq.

  As a result, the transfer function from the motor target speed MVr to the motor speed (actual value) MV in the closed-loop system constituted by the motor speed control system 160 and the motor target speed correction unit 180 is such that the motor predicted response time Tmt is actually If the motor response time Tmt # is substantially the same, the following equation (2) is obtained.

MV (s) / MVr (s) = 1 / (Trqc · s + 1) (2)
By setting Trqc = Trq / 4 as described above, the motor rotation speed (actual value) MV at the time when the clutch engagement request time Trq has elapsed is settled with respect to the motor target rotation speed MVr.

  Referring to FIG. 2 again, the speed control of rear motor 90 by motor speed control system 150 shown in FIG. 4 is continued until clutch engagement request time Trq (Trq = 4 · Trqc) elapses (step S150). When the clutch engagement request time Trq elapses, an engagement instruction is actually issued from the ECU 60 to the clutch 95 (step S160). In response to this, the clutch 95 is mechanically engaged, and the clutch engagement is completed (step S170).

  FIG. 5 is an operation waveform diagram showing an example of clutch engagement control according to the embodiment of the present invention.

  Referring to FIG. 5, when the accelerator depression amount suddenly increases from P1 to P2 at time t0, “rapid acceleration” is recognized, and the clutch engagement request flag is turned on (“1”) at time t1.

  Further, the wheel speed WV increases due to an increase in driving force according to the depression of the accelerator. The change in the accelerator depression amount is also reflected in the calculated value DF of the vehicle driving force by the ECU 60.

  In response to turning on of the clutch engagement request flag, according to the flowchart shown in FIG. 4, the clutch engagement request time Trq corresponding to the driving situation at the time t1 is determined, and the rear motor 90 is started, as shown in FIG. The motor speed control system 150 controls the speed (number of rotations).

  As shown in FIG. 5, the response waveform of the motor current varies depending on the difference in motor response time Tmt # corresponding to the motor condition. However, as understood from the above equation (2), the motor speed response after the time t1 after the clutch engagement request is generated depends only on the clutch engagement request time constant Trqc, that is, the desired clutch engagement request time Trq. Become.

  Therefore, at the time t2 when the clutch engagement request time Trq has elapsed from the time t1, the rotation speed (speed) MV of the rear motor 90 is not affected by the motor conditions, and the wheel speed WVr of the rear wheels 20L and 20R at the time t2. The target rotational speed MVr is controlled in synchronization with Thereby, at time t2, the torque shock is suppressed and the clutch 95 is actually engaged, and clutch torque is generated.

  Therefore, in an automobile equipped with the electric vehicle drive device according to the present embodiment, the torque shock is suppressed when the clutch engagement request time determined according to the driving situation elapses without being influenced by the operating condition of the motor. The clutch can be engaged. As a result, the response time until the clutch is engaged can be set to a desired value according to the driving situation without being influenced by the operating condition of the motor, so that drivability is improved.

  Further, it is possible to reduce motor drag loss and friction loss without problems such as delay in clutch response and engagement shock.

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

It is a block diagram explaining the structure of the motor vehicle provided with the electric drive device for vehicles according to this invention. It is a flowchart explaining the clutch fastening control system according to the embodiment of the present invention. It is a conceptual diagram explaining the determination method of the estimated response time of a motor, and a clutch fastening request | requirement time. It is a block diagram which shows the control system of motor speed (rotation speed). It is an operation | movement waveform diagram which shows an example of the clutch fastening control according to embodiment of this invention.

Explanation of symbols

  10L, 10R front wheel, 15 accelerator pedal, 20L, 20R rear wheel, 30 front drive unit, 40 rear drive unit, 50 engine, 80 battery, 90 rear motor, 95 clutch, 100 automobile, 110, 115 map, 150, 160 motor speed Control system, 170 motor target speed calculation unit, 180 motor target speed correction unit, MVr original motor target speed, MVr # actual (corrected) target speed, Tmt # motor response time (actual time constant) ), Tmt predicted motor response time (time constant), Trq clutch engagement request time, Trqc clutch engagement request time constant, WV wheel speed.

Claims (8)

An electric motor capable of driving wheels;
A wheel driven by the electric motor and a clutch disposed between the electric motor,
A control device for controlling driving of the vehicle,
The control device calculates a target rotational speed of the electric motor corresponding to an estimated wheel speed after a lapse of a desired clutch engagement request time when there is a clutch engagement request, and further calculates the clutch engagement request time. After the elapse of time, the motor is controlled so that the rotation speed of the motor reaches the target rotation speed,
The clutch is a vehicle drive device that engages between the electric motor and the wheel after the clutch engagement request time has elapsed based on an instruction from the control device.   The vehicle drive device according to claim 1, wherein the clutch engagement request time is determined according to a driving situation.   The vehicle drive device according to claim 1, further comprising a wheel drive source other than the electric motor.   The vehicle drive device according to claim 3, wherein the clutch engagement request is issued according to a driving situation while the vehicle is traveling.   The control device calculates the estimated wheel speed and the target rotational speed based on a detected value of the rotational speed of the wheel and a calculated value of the driving force of the wheel when the clutch is requested to be engaged. The vehicle drive device according to claim 1.   The control device corrects the target rotational speed calculated corresponding to the estimated wheel speed according to an actual rotational speed of the electric motor, the clutch engagement request time, and a predicted response time of the electric motor, and corrects the electric motor. The vehicle drive device according to claim 1, wherein a control system is configured such that a response characteristic of the rotation speed of the electric motor with respect to the target rotation speed depends on the clutch engagement request time by performing the control. The target rotational speed calculated corresponding to the estimated wheel speed is MVr, the corrected target rotational speed is MVr #, the predicted response time of the motor is Tmt, and the clutch engagement request time constant based on the clutch engagement request time is Trqc, where the actual rotational speed of the motor is MV,
MVr # = (Tmt / Trqc) .MVr- (Tmt / Trqc-1) .MV
The vehicle drive device according to claim 6, wherein the electric motor is controlled using the corrected target rotational speed MVr # obtained in accordance with The predicted response time of the motor is determined according to the operating conditions of the motor,
The vehicle drive device according to claim 6, wherein the operating condition includes at least one of a temperature, a current, and a rotation speed of the electric motor.

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