JP5245681B2 - Driving force control device - Google Patents

Description

  The present invention relates to a driving force control device for controlling the driving force or braking force of at least two left and right wheels of a vehicle.

  Conventionally, a vehicle that is driven by providing a drive device (for example, an electric motor) on at least two left and right wheels of the vehicle is known. One example thereof is described in Patent Document 1. The vehicle described in Patent Document 1 is an industrial vehicle, and an electric motor is provided on each wheel. In the vehicle described in Patent Document 1, when any one of the wheels stops operating due to some failure or the like, the vehicle can be moved by the driving force of the other normally operating wheels. Yes.

  Further, in the vehicle described in Patent Document 2, a drive device and its control device are individually provided on at least two left and right wheels of each wheel of the vehicle, and either of the control devices of the drive device (electric motor). If either one fails, the fail-safe function works. The fail-safe function is intended to harmonize the driving force of the left and right two wheels by substituting the control device of the motor that operates normally for the malfunctioning motor.

JP-A-11-127506 JP 2004-175313 A

  In the vehicle described in Patent Document 1, when an abnormality occurs in driving the wheel, the wheel in which the abnormality has occurred is stopped and the other normally operating wheels are driven to move. In this control method, when the vehicle is driven by driving normally operating wheels, the left and right driving forces are unbalanced, and the running stability of the vehicle is impaired, which may cause yawing and the like.

  In addition, in the vehicle described in the above-mentioned Patent Document 2, when the motor control device provided on each wheel fails, the other left and right control devices are harmonized by other normally operating control devices, and the vehicle stability is improved. A configuration for ensuring the above is described. However, there was still room for improvement with regard to regeneration by the motor that operates normally between the two left and right wheels at the time of failure.

  The present invention has been made paying attention to the above technical problem, and is intended for a vehicle in which a drive device and a brake mechanism are provided for each wheel. An object of the present invention is to provide a driving force control device that can ensure vehicle stability and perform regeneration by a driving device that operates normally to improve energy efficiency.

In order to achieve the above object, the invention according to claim 1 is provided by a drive device that is individually provided on at least two left and right wheels of the front and rear wheels, and that increases or decreases the drive torque and has a power generation function, and is operated by hydraulic pressure. In the driving force control device provided with a brake mechanism that individually applies a braking force to each of the left and right wheels, a failure determination unit that determines whether one of the left and right wheels has failed. When the failure of the one drive device is detected, the drive device in which the failure is detected and the wheel connected to the drive device are mechanically disconnected, and the other failure is not detected. and interrupting means for mechanically disconnecting the wheel is connected to a drive unit and the drive unit, during braking request when the failure of one of the driving device is detected, the failure detection To be the wheel driving device failure beauty the other hand Oyo wheels provided is not detected driving device is provided, a braking instruction unit for applying a braking force by the brake mechanism, of the other Braking force switching means for causing a braking force applied by the braking instruction means to a wheel provided with a driving device in which no failure is detected to be transferred from a braking force by the brake mechanism to a braking force by the driving device. It is characterized by that.

According to the first aspect of the present invention, a failure of the drive device is detected by the failure determination means, the braking force by the brake mechanism is applied to the left and right two wheels by the braking instruction means, and no failure is detected. The braking force applied to the wheels connected to the vehicle is shifted from the braking force by the braking mechanism to the braking force by the driving device by the braking force switching means, so that braking or regeneration by the driving device is possible while ensuring vehicle stability. It becomes . Further, energy loss can be reduced by mechanically disconnecting the drive device in which the failure is detected from the wheel.

  Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows an example of a configuration of a vehicle and a control system targeted by the present invention. As an example, a vehicle Ve shown in FIG. 1 is a hybrid four-wheel drive vehicle that is driven using an internal combustion engine and a motor as power sources. That is, the engine (ENG) 1 and the motor generators (MG1, MG2) 2, 3 having a power generation function are provided as power sources, and all four wheels can be driven.

  The engine 1 is a power engine that outputs power by burning a fuel such as a gasoline engine, a diesel engine, or a natural gas engine. The output is electrically automatically output by an engine electronic control unit (engine ECU) (not shown). Can be controlled. Further, the internal combustion engine can be set to an optimum operating point with the best fuel efficiency by controlling the rotational speed with respect to a predetermined load. In the example shown in FIG. 1, the engine 1 is arranged in the front direction of the vehicle and is configured to drive the rear wheels by a transmission mechanism. The vehicle Ve is FR (front engine / rear drive) in terms of the engine drive system. ) Method. It should be noted that the engine 1 may be arranged at any position in the vehicle with respect to this engine drive system, and may be configured to be an RR (rear engine / rear drive) system or other system.

  A transmission 4 is connected to the engine 1, and a differential is connected to the output side of the transmission 4 via a propeller shaft 5. Furthermore, each of a right rear wheel (RR) 8 and a left rear wheel (RL) 9 is individually connected to the differential via left and right axles 6 and 7. In the configuration of the vehicle that is the subject of the present invention, the engine 1 is not an internal combustion engine, but a motor / generator or other motor, or a motor / generator (electric motor) is separately provided for the two rear wheels. A configuration in which the vehicle is driven individually and the vehicle Ve is not a hybrid vehicle but an electric vehicle may be employed.

  The motor generators (motors) 2 and 3 provided on the left and right two wheels (the right front wheel 10 and the left front wheel 11) function as a generator and an electric motor as an example, that is, convert electric energy into kinetic energy. The electric motor is configured to have both a power running function to perform and a regenerative function to convert kinetic energy into electric energy. Note that the energy converted into electric energy by the regenerative function can be further converted into chemical energy and stored.

  The motor generators 2 and 3 are in-wheel motors that are provided in the vicinity of the right front wheel (FR) 10 and the left front wheel (FL) 11 or inside the wheel, and form a structure for individually driving the two front wheels 10 and 11. The structure of the power transmission mechanism is such that the axles 14 and 17 are coaxially connected from the motor / generators 2 and 3, respectively, and the clutch 13 is configured so that transmission and interruption of power can be performed in stages. , 16 is transmitted to the axles 12, 15 so that the right front wheel 10 and the left front wheel 11 can be driven. The driving mechanism of each wheel by the motor / generators 2 and 3 can be controlled by an electronic control device such as a motor control device (motor ECU) 18 or 19, and the vehicle is based on the operation intention of the driver. Control that receives a command from the ECU 39 or the like and control according to the traveling state of the vehicle are possible.

  Further, motor control devices (motor ECUs) 18 and 19 for controlling the motor / generators 2 and 3 are configured to perform braking / driving control of the motor / generator by inputting / outputting signals to / from an inverter or an electric circuit (not shown). It is said that. The motor ECUs 18 and 19 are connected to a power storage device 20 such as a battery or a capacitor so that power can be exchanged. The power storage device 20 supplies electric power when the motor / generators 2 and 3 are operated as motors, and operates the motor / generators 2 and 3 as generators to convert regenerative power from electric energy to chemical energy. Can be stored.

  In each motor / generator 2, 3, the rotor torque (not shown) is stored in the motor / generator 2, 3 through the axles 12, 14, the clutches 13, 16 and the axles 15, 17. The kinetic energy generated by the inertial rotation of the rotor is converted into electric energy, and the power storage device 20 such as a battery or a capacitor can be charged, that is, regenerated via motor control devices (motor ECUs) 18 and 19. . This regeneration function is controlled by the regeneration ECU 21.

  Each of the right front wheel 10 and the left front wheel 11 is provided with a hydraulic friction brake. That is, a disc rotor 22, a brake caliper 23, a wheel cylinder 24, and a pressure sensor 25 are provided on the axle 12 side of the right front wheel 10, and are configured to be able to perform braking by friction by operating these. . Similarly, a disc rotor 26, a brake caliper 27, a wheel cylinder 28, and a pressure sensor 29 are provided on the axle 15 side of the left front wheel 11, and are configured to be capable of braking by friction by operating these. ing.

  In this hydraulic friction brake, when the brake pedal 30 is depressed and braking is performed, the master cylinder 34 is operated by a vacuum pump 31, a motor 32, a vacuum booster 33, and the like provided to amplify the pedal depression force. The hydraulic pressure is amplified and sent to the wheel cylinders 24 and 28 via the hydraulic control device 35 to drive the brake calipers 23 and 27. Then, by pressing a brake pad (not shown) in the brake calipers 23 and 27, the kinetic energy is converted into thermal energy, and the vehicle is braked by friction, that is, the brake is effective. In addition, these hydraulic pressure controls are configured to be performed by the hydraulic ECU 36 so that braking by friction and hydraulic pressure for performing the control can be appropriately controlled. The friction brake by hydraulic pressure is configured to perform braking in conjunction with regenerative braking by the motor generators 2 and 3 described below.

  In the brake cooperative control (regenerative cooperative control) using the friction brake and the regenerative brake, when the brake pedal 30 is operated, the brake pedal sensor 37 obtains the required braking force based on the degree of depression. The required braking force can be generated by any of the above-described friction brake and regenerative braking by the motor / generators 2, 3. Therefore, the required braking force depends on the vehicle speed at the time of the braking operation, the SOC (charge capacity) of the battery, etc. Based on this, a brake mechanism that generates a braking force is selected. Also, a mechanism for generating a braking force is selected depending on the presence or absence of a failure. A brake / motor integrated ECU 38 is provided for performing such braking control and selection of a mechanism for generating braking force. The brake / motor integrated ECU 38 outputs signals to the regenerative ECU 21 and the hydraulic ECU 36 described above, so that the braking / driving control of the right front wheel 10 and the left front wheel 11 is comprehensively performed by the regenerative ECU 21 and the hydraulic ECU 36. Yes.

  The brake / motor integrated ECU 38, the regenerative ECU 21 and the hydraulic ECU 36 described above are further connected to the vehicle ECU 39 so as to be communicable. By this vehicle ECU 39, the running state of the vehicle can be sensed by sensors provided in each part of the entire vehicle in a timely manner, and can be comprehensively managed so that the vehicle can run in an optimum state.

  Further, the present invention relates to braking at the time of failure of the drive devices provided at least on the left and right two wheels. The failure of the drive device targeted by the present invention is, for example, a vehicle target in the failure determination means. The difference between the braking force and the actual vehicle braking force exceeds a predetermined value, or the difference between the target driving force of the vehicle and the actual driving force of the vehicle exceeds a predetermined value. A case where it is determined that there is a possibility is considered. Note that the failure determination means is not limited to this, and may be another calculation method. In addition, the failure determination is performed by the vehicle ECU 39 and sensors (not shown) provided in each part.

  Furthermore, the state determined as such a failure may occur due to deterioration of component parts (aging), failure of the component parts, or sudden breakage / deletion of the component parts. When such a failure occurs, the location where the failure has occurred is determined instantaneously by various sensors and transmitted to each ECU or the like. In the present invention, when a failure occurs in any one of the left and right wheels, a necessary braking force is generated while maintaining vehicle stability. More specifically, if a failure occurs on the regenerative brake side on either the left or right wheel, the braked one wheel is braked with a hydraulic brake, while the normal one wheel side uses both a friction brake and a regenerative brake. The necessary total braking force can be obtained by the cooperation of and the regeneration is also performed.

  FIG. 2 is a flowchart schematically showing control of the drive device on the failed side and the drive device on the normally operating side in the present invention. First, it is determined whether or not a failure has been detected (step S101). If a negative determination is made in step S101 because no failure has been detected, the process returns to the start of the flowchart again. On the other hand, if a failure is detected and a positive determination is made in step S101, the wheel of the drive device in which the failure is detected is braked by the friction brake (step S102). Further, in the drive device that operates normally, braking is executed while shifting from the friction brake to the regenerative brake by the drive device.

  Further, in FIG. 3, an example of the configuration of FIG. 1 will be described in detail with reference to a flowchart regarding the braking control by the left and right two-wheel drive devices of the present invention. First, it is determined whether one of the right front wheel 10 and the left front wheel 11 has failed (step S201), and a negative determination is made in step S201 because no failure has been detected from either of the wheels 10, 11. If it is, return to the original. If a failure is detected in either one of the left and right two wheels 10 and 11 and an affirmative determination is made in step S201, then as a procedure for specifying which one of the left and right wheels is the failure part, It is determined whether only the right front wheel 10 is present (step S202). If a failure is detected only in the right front wheel 10 and an affirmative determination is made in step S202, the power of the right front wheel 10 and the left front wheel 11 is cut off (step S203). Then, it is determined whether or not there is a braking request (step S204). If it is determined negative in step S204 because there is no braking request, a loop is made and this determination (step S204) is repeated again. Further, when the determination is positive in step S204 due to the request for braking, braking of the left and right two wheels of the vehicle is performed by regenerative cooperative control. That is, the right front wheel 10 which is the failure part is braked by the hydraulic brake, and the normal left front wheel 11 is braked while shifting from the hydraulic brake to the regenerative brake (step S205).

  On the other hand, if a negative determination is made in step S202 that the failure is not only the right front wheel 10, it is further determined whether or not the failure part is only the left front wheel 11 (step S206). If the failure part is only the left front wheel 11 and a positive determination is made in step S206, the power of the right front wheel 10 and the left front wheel 11 is cut off (step S207). Next, it is determined whether or not there is a braking request (step S208). If it is determined negative in step S208 because there is no braking request, a loop is made and this determination is performed again. If a positive determination is made in step S208 because there is a braking request, braking of the left and right wheels of the vehicle is executed by regenerative cooperative control. That is, the left front wheel 11 which is a failure part is braked by the hydraulic brake, and the braking is executed while the shift from the hydraulic brake to the regenerative brake is performed on the right front wheel 10 side which operates normally (step S209).

  Further, when a negative determination is made in step S206 above because the failure part is not only the left front wheel 11, that is, when it is determined that the failure part is both the left and right wheels, the right front wheel 10 and the left The power with the front wheel 11 is cut off (step S210). Next, it is determined whether or not there is a braking request (step S211). If it is determined negative in step S211 because there is no braking request, a loop is made and this step is determined again (step S211). . If a positive determination is made in step S211 due to the demand for braking, both the right front wheel 10 and the left front wheel 11 are braked by a hydraulic brake (step S212).

  4 and 5 are diagrams showing time on the horizontal axis and braking torque on the vertical axis regarding the braking operation during failure of the left and right two wheels according to the present invention shown in FIGS. FIG. 4 is a diagram schematically showing changes in braking torque and time of the failed drive device. FIG. 5 is a diagram schematically showing changes in braking torque and time of the drive device on the side that operates normally.

  The temporal change in braking on the failed wheel side will be described with reference to FIG. 4. In braking on the failed wheel side, braking torque from the hydraulic brake starts to be applied from time T11 due to a braking request. At this time, the power is cut off on the regenerative brake side because of one-side wheel drive abnormality. The braking torque by the hydraulic brake gradually increases to the one-wheel command (necessary) torque in a short time, and a predetermined braking torque is applied to the wheels.

  Next, a temporal change in braking on the wheel side that operates normally will be described with reference to FIG. 5. It is possible to apply a braking force to the wheel by operating a regenerative braking torque immediately from time T21 if normal. However, in the present invention, first, braking by hydraulic pressure is performed from time T21, a delay time is provided, the hydraulic braking torque is decreased from around time T22, and the regenerative braking torque is gradually increased to an appropriate degree. The regenerative braking control and regenerative braking torque by this method are used to provide one-wheel command (necessary) braking torque to the wheel, thereby providing the braking torque necessary for braking the normally operating wheel and driving. The vehicle can be braked and regenerated even at the time of failure without impairing stability. If the vehicle ECU 39 or the like determines that the behavior of the vehicle is likely to be unstable based on information acquired by various sensors (for example, a high-G state or turning), It is possible to shift to regeneration while further stabilizing the vehicle behavior by taking a longer delay time and providing a margin time until the behavior of the vehicle is stabilized by braking by the hydraulic brake.

  Further, the control of the driving force control device of the present invention will be described again. In a range where the actual power value cannot be allowed with respect to the target driving force value of the brake / motor integrated ECU 38 from the sensor provided in the vehicle driving device. In the case of a small value or the like, it is possible to avoid loss of electric power or the like by determining that the driving device on the one-wheel side is out of order and shutting it off electrically or mechanically. After that, when there is a braking request, braking torque is applied by the hydraulic brake on the malfunctioning drive device side, and braking torque is applied by the hydraulic brake on the drive device on the normally operating side to stabilize the vehicle. Regenerative torque is gradually applied by the motor / generator 2 (or 3) in a state in which the power is maintained, braking is performed by regenerative cooperative control, and the required braking can be performed while regenerating electric power.

  As described above, in the configuration example described above, the two left and right wheels to be individually controlled to be controlled are two front wheels, but the two left and right wheels to be individually controlled to be controlled are two rear wheels. In addition, both front and rear wheels are individually driven by a motor / generator, and the control of the left and right wheels to be individually driven is applied to both the front wheels and the rear wheels. A configuration in which two front wheels and two rear wheels are cooperatively controlled via an electronic control unit or the like may be employed. Further, in the above configuration example, the electronic control unit (ECU) provided in each mechanism is individually provided. However, each ECU is configured to be partially integrated with each other in any case. Alternatively, a configuration may be provided in which an ECU that performs integrated control management of the entire vehicle is provided.

1 is a conceptual diagram schematically showing an example of a configuration of a vehicle to which a braking force control device of the present invention can be applied. 2 is a flowchart schematically showing a control example of the braking force control apparatus shown in FIG. 1. 2 is a flowchart specifically illustrating a control example of the braking force control apparatus illustrated in FIG. 1. It is a diagram showing the relationship between the braking torque of the failure side drive device by the braking force control device of this invention and time. It is a diagram showing the relationship between the braking torque of the normal side drive device by the braking force control apparatus of this invention, and time.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Right front wheel, 11 ... Left front wheel, Brake | motor motor integrated ECU38, 39 ... Vehicle ECU.

Claims (1)

A drive device that is individually provided on each of the left and right wheels of at least one of the front and rear wheels and that increases / decreases the drive torque and has a power generation function, and a brake that operates by hydraulic pressure and individually applies a braking force to each of the left and right wheels In the driving force control device provided with the mechanism,
Failure determination means for determining whether one of the left and right two wheels has failed ;
When a failure of the one drive device is detected, the drive device in which the failure is detected and a wheel connected to the drive device are mechanically disconnected, and the other drive device in which no failure is detected And a blocking means for mechanically blocking the wheel connected to the drive device,
During braking request when the failure of one of the driving device is detected by the failure wheels detected drive is provided with and failure of the other hand is not detected driving device provided Braking instruction means for applying a braking force by the brake mechanism to the existing wheel;
Braking force switching means for shifting the braking force applied by the braking instruction means to the wheel provided with the driving device in which the other failure is not detected from the braking force by the brake mechanism to the braking force by the driving device. And a driving force control device.

Images