Control system

Abstract

To provide a control system that reduces a risk of breakdown, weight, and cost.SOLUTION: A control system comprises: a power train control device which controls torque to drive a power train connected to front wheels of a vehicle through a transmission based on an accelerator opening; a steering control device which steers the front wheels based on a steering amount applied to a steering; a rear wheel motor control device which controls right and left rear wheels by outputting torque instructions to each of rear motors installed on the right and left rear wheels of the vehicle; and a vehicle main control device which calculates a torque difference between the right and left rear wheels based on the steering amount and the accelerator opening. The rear wheel motor control device calculates the torque instructions output to the rear motors based on the torque difference calculated by the vehicle main control device.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a control system. [Background technology]

[0002] In order to realize small turning radius at low speeds and improve driving stability, vehicle stability, and controllability at medium and high speeds, 4WS vehicles are known that allow four-wheel steering by a steering device by providing steering function not only to the front wheels but also to the rear wheels. As a publicly known example of 4WS, the following Patent Document 1 discloses the configuration of a vehicle equipped with a differential gear that reduces the minimum turning radius of a four-wheeled vehicle. In this technology, a method is adopted in which torque is distributed to auxiliary drive wheels by a single motor to improve turning performance. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2006-44319 A Summary of the Invention [Problem to be solved by the invention]

[0004] Conventional 4WS systems generate a rotation difference from zero torque, which raises concerns about increased running resistance when the driver operates the steering wheel, and providing a steering function by equipping the rear wheels with a steering device increases the number of parts, which leads to disadvantages such as increased weight, increased risk of failure, and increased costs. Therefore, by electrifying vehicles and modularizing the vehicle structure, and in particular by adopting electric four-wheel drive, rear-wheel drive has become a drive system driven by a single motor equipped on the rear wheels, which ensures driving stability because the rear wheels can be driven even if the front wheels slip, and also makes it possible to use the space in the rear wheels to install a small motor in-wheel.

[0005] However, in this type of system, since the motor is a single unit, it is not possible to precisely control the left and right rear wheels, and it is not possible to generate an optimal yaw moment. In view of this, an object of the present invention is to provide a control system that realizes a reduced risk of failure, weight reduction, and cost reduction. [Means for solving the problem]

[0006] The control system of the present invention comprises a powertrain control device that controls the torque driving a powertrain connected to the front wheels of the vehicle via a transmission based on the accelerator opening degree; a steering control device that steers the front wheels based on the steering amount; a rear wheel motor control device that outputs a torque command to rear motors provided on the left and right rear wheels of the vehicle, respectively, to control the left and right rear wheels; and a vehicle main control device that calculates the torque difference between the left and right rear wheels based on the steering amount and the accelerator opening degree, and the rear wheel motor control device calculates the torque command to be output to the rear motor based on the torque difference calculated by the vehicle main control device. Effect of the Invention

[0007] According to the present invention, it is possible to provide a control system which realizes a reduced risk of failure, weight reduction, and cost reduction. [Brief description of the drawings]

[0008] [Figure 1] 1 is a diagram of a control system according to an embodiment of the present invention; [Diagram 2] Control flow of electric four-wheel drive control computer [Diagram 3] Basic control flow of rear wheel motor control computer [Figure 4] Basic control flow for steering [Diagram 5] 1 is a control flow diagram of a control system according to an embodiment of the present invention; [Figure 6] 1 is a control flow diagram showing a case where a drive request is made to the rear motor according to an embodiment of the present invention; [Figure 7]A control flow taking into consideration a case where there is no drive request to the rear motor according to an embodiment of the present invention. [Figure 8] Control flow for determining the magnitude of a turn request according to an embodiment of the present invention [Figure 9] Control flow for limiting the calculated torque difference according to an embodiment of the present invention [Figure 10] 1 is a characteristic diagram showing torque difference limiting according to an embodiment of the present invention; [Figure 11] Control flow based on torque request prioritization according to one embodiment of the present invention DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The following description and drawings are examples for explaining the present invention, and appropriate omissions and simplifications have been made for clarity of explanation. The present invention can be implemented in various other forms. Unless otherwise specified, each component may be singular or plural.

[0010] In order to facilitate understanding of the invention, the position, size, shape, range, etc. of each component shown in the drawings may not represent the actual position, size, shape, range, etc. Therefore, the present invention is not necessarily limited to the position, size, shape, range, etc. disclosed in the drawings.

[0011] (One embodiment and overall configuration) (Figure 1) A vehicle 100 equipped with a motor control system has a front right tire FR, a front left tire FL, a rear right tire RR, and a rear left tire RL. The front right tire FR is equipped with a right front wheel speed sensor 10FR, the front left tire FL is equipped with a left front wheel speed sensor 10FL, the rear right tire RR is equipped with a right rear wheel speed sensor 10RR, and the rear left tire RL is equipped with a left rear wheel speed sensor 10RL. The rear right tire RR is equipped with a right rear wheel motor 2R, and the rear left tire RL is equipped with a left rear wheel motor 2L, so that the left and right rear wheels are each equipped with two independent rear motors.

[0012] The motor control system has a rear wheel motor control computer 20, a vehicle main computer 21, an electric four-wheel drive control computer 22, a powertrain control computer 23, an air conditioning control computer 24, and a steering control computer 25, and each control device is connected to each other via an in-vehicle communication network 30, allowing information to be input and output.

[0013] A rear wheel motor control computer 20, which is an inverter, controls the turning of the rear right tire RR and the rear left tire RL by outputting a torque command (torque request) to the rear right wheel motor 2R and the rear left wheel motor 2L.

[0014] The electric four-wheel drive control computer 22 acquires information such as vehicle speed from the left rear wheel speed sensor 10RL, the left front wheel speed sensor 10FL, and the right front wheel speed sensor 10FR and the right rear wheel speed sensor 10RR (not shown). The electric four-wheel drive control computer 22 also detects the degree of slip of the front wheels via the wheel speed sensor 10, and outputs a torque output request to the rear motors 2R, 2L to the vehicle main computer 21 based on the degree of slip.

[0015] An air compressor 5 is attached to the engine 3e, which is a power train. An air conditioner control computer 24 controls the air compressor 5 by acquiring outside air temperature information from the outside air temperature sensor 11, and also outputs the outside air temperature information to the vehicle main computer 21.

[0016] The steering control computer 25 is connected to the steering actuator 4a and steers the front wheels based on the steering amount of the steering wheel. The steering control computer 25 also obtains steering information of the steering wheel 6 via the steering angle sensor 12 that detects the steering amount when the steering wheel 6 is operated, and outputs the steering information to the vehicle main computer 21.

[0017] The steering actuator 4a is connected to the front right tire FR and the front left tire FL via a steering link mechanism 4l, and controls the front right tire FR and the front left tire FL based on a higher-level drive request. The transmission 3t is connected to the front right tire FR and the front left tire FL. The transmission 3t is connected to the powertrain control computer 23.

[0018] The powertrain control computer 23 is connected to the accelerator pedal 7, and detects the accelerator opening, which is the amount of operation of the accelerator pedal 7, via the accelerator opening sensor 7s, and outputs the information to the vehicle main computer 21. The powertrain control computer 23 is also connected to the transmission 3t and to the engine 3e, which is a powertrain connected to the front wheels FR, FL by the transmission 3t, and controls the drive torque in response to the accelerator opening. The engine 3e may be a motor. The powertrain control computer 23 outputs the acquired information to the vehicle main computer 21.

[0019] In order to improve the controllability and stability of the vehicle, the vehicle main computer 21 calculates the amount of yaw moment required depending on the magnitude of the turning request by combining the acquired steering amount with information such as the accelerator opening degree to create a difference in drive torque between the left and right rear wheels. The vehicle main computer 21 outputs a required torque including the calculated torque difference to the rear wheel motor control computer 20. The rear wheel motor control computer 20 outputs a torque command to the rear motors 2L, 2R based on the acquired torque difference.

[0020] By having the rear motors 2L, 2R output torque based on the command torque, when it is desired to turn the vehicle, the torque on the side to be turned is reduced to generate a torque difference, which generates a yaw moment in the vehicle and improves the turning ability of the vehicle. Note that the control may be based on the driving force.

[0021] (Figure 2) The following describes the basic control flow of the electric four-wheel drive control computer 22, which is the premise of the invention. In step 22-1, an accelerator pedal signal including information about the accelerator opening degree obtained from the powertrain control computer 23 via the accelerator opening degree sensor 7s is read.

[0022] In step 22-2, it is determined whether the read accelerator pedal signal indicates a request for engine acceleration based on whether the accelerator opening value contained in the accelerator pedal signal is equal to or greater than a predetermined threshold. If it is determined that there is a request for engine acceleration (Yes), then in step 22-3, the vehicle speed is read via wheel speed sensors 10FL, 10FR, 10RR, and 10RL. If there is no request for engine acceleration (No), then no torque output request is made in step 22-9.

[0023] In step 22-4, the front average vehicle speed of the vehicle is calculated. For example, the formula for calculating the front average vehicle speed Vf is Vf=(value of sensor 10FL+value of sensor 10FR) / 2.

[0024] In step 22-5, the average rear vehicle speed of the vehicle is calculated. For example, the formula for calculating the average rear vehicle speed Vr is Vr=(value of sensor 10RL+value of sensor 10RR) / 2.

[0025] In step 22-6, a difference between the front and rear vehicle speeds is calculated based on the front average vehicle speed Vf and the rear average vehicle speed Vr calculated in steps 22-4 and 22-5, respectively. For example, the equation for calculating the front and rear vehicle speed difference Vref is Vref=front average vehicle speed Vf-rear average vehicle speed Vr.

[0026] In step 22-7, it is determined whether the front wheels are slipping (front spinning). If they are slipping (Yes), in step 22-8 a torque output request is made to the vehicle main computer 21 to the rear motor. If there is no slipping (No), in step 22-9 no torque output request is made to the rear motor. Note that the torque output request amount associated with this can be adjusted, for example, by increasing it by a predetermined amount while there is slipping, and decreasing it by that amount when the slipping disappears.

[0027] (Figure 3) The basic control flow of the rear wheel motor control computer 20 will be described. In step 20-1, a torque output request output from the vehicle main computer 21 is read. In step 20-2, it is determined whether the read information includes a torque output request, and if there is an output request (Yes), power running control of the rear motor is performed in step 20-3. If there is no output request (No), power running control of the rear motor is not performed in step 20-4.

[0028] (Figure 4) A basic control flow of the steering control computer 25 will be described. In step 25-1, a steering signal indicating the opening degree of the steering wheel 6 is read from the steering angle sensor 12. In step 25-2, a steering demand amount is calculated based on the steering amount contained in the read steering signal. In step 25-3, a drive demand is output to the steering actuator 4a via a pinion gear (not shown in FIG. 1) based on the calculated steering demand amount so that a predetermined steering angle is obtained.

[0029] Incidentally, the electric power steering mechanism associated with the steering 6 does not necessarily need to be electrically connected to the steering control computer 25, and may be directly connected to the steering control computer 25 mechanically.

[0030] (Figure 5) The control flow of the motor control system of the present invention will be described. In step C1-1, the vehicle main computer 21 reads out the steering amount of the steering wheel 6 detected by the steering angle sensor 12 from the steering control computer 25. In step C1-2, the vehicle main computer 21 reads out the accelerator opening detected by the accelerator opening sensor 7s from the powertrain control computer 23. In step C1-3, the vehicle main computer 21 calculates the torque difference between the left and right rear wheels based on the steering amount and accelerator opening read out by the vehicle main computer 21. In step C1-4, the rear wheel motor control computer 20 obtains the torque difference calculated by the vehicle main computer 21 and issues a torque output request to the rear motors 2L, 2R based on the obtained torque difference.

[0031] In this way, by using two independent rear motors for the left and right wheels, the torque can be freely controlled in response to the steering amount and throttle opening, so that when combined with front wheel steering, it can provide a function that replaces 4WS.Since the yaw moment can be controlled more precisely than before, the vehicle's cornering performance can be improved.

[0032] (Figure 6) The control flow of the motor control system according to the present invention when there is a drive request for the rear motors 2L, 2R will be described below. In step C2-1, the vehicle main computer 21 reads out a drive request for the rear motors 2L, 2R from the electric four-wheel drive control computer 22.

[0033] In step C2-2, the vehicle main computer 21 checks whether there is a drive request to the rear motors 2L, 2R, and if there is a drive request (Yes), in step C2-3, the vehicle main computer 21 calculates the torque difference between the left and right rear wheels based on the steering operation amount and the accelerator opening, and determines the torque to be distributed to each of the rear motors 2L, 2R based on the calculated torque difference. The vehicle main computer 21 makes a torque output request including the determined torque distribution to the rear wheel motor control computer 20. In step C2-4, the rear wheel motor control computer 20 outputs a torque output command to the rear motor based on the torque output request acquired from the vehicle main computer 21. If there is no drive request in step C2-2 (No), the vehicle main computer 21 does not make a torque output request in step C2-5.

[0034] (Figure 7) 13 is a control flow of the motor control system according to the present invention, taking into consideration the case where there is no drive request for the rear motors 2L, 2R (the rear wheels are coasting). In step C4-1, the vehicle main computer 21 reads out a drive request for the rear motors 2L, 2R from the electric four-wheel drive control computer 22.

[0035] In step C4-2, the vehicle main computer 21 checks whether the read drive requests include a drive request to the rear motors 2L, 2R, and if there is a drive request (Yes), calculates the torque difference between the left and right rear wheels based on the steering operation amount and the accelerator opening. In step C4-4, the rear wheel motor control computer 20 issues a torque output request to the rear motors 2L, 2R based on the torque difference between the rear wheels calculated by the vehicle main computer 21. Note that the above steps C4-1 to C4-4 are the same as steps C2-1 to C2-4 in FIG. 6.

[0036] If the vehicle main computer 21 determines in step C4-2 that there is no drive request from the electric four-wheel drive control computer 22 (No), then in step C4-5, it calculates a torque difference based on the steering angle and the accelerator opening, and reads out a turning request determination result based on the steering angle and the vehicle speed, as will be described later in FIG. 8.

[0037] In step C4-6, the vehicle main computer 21 determines whether the read-out turning request amount is greater than a predetermined standard, and if it is greater than the predetermined standard (Yes), in step C4-7, it calculates a regenerative torque for one of the rear wheels based on the steering amount, accelerator opening, and turning request amount, and calculates a powering torque for the other rear wheel. In step C4-6, if the turning request amount is equal to or less than the predetermined standard (No), in step C4-8, it calculates a regenerative torque for one of the rear wheels based on the steering amount and accelerator opening.

[0038] In this way, even when there is no drive request from the rear motors 2L, 2R, the vehicle main computer 21 applies regenerative force to one of the rear wheels to create a torque difference, improving vehicle stability at medium speeds and above. In addition, since the rotation difference can be generated with positive torque, there is an advantage that it does not cause running resistance. Furthermore, if the rotation difference is generated with negative torque, braking can be performed regeneratively, and the regenerative energy can be converted to improve fuel efficiency.

[0039] (Figure 8) The flow of determining the turning request amount of the motor control system of the present invention will be described. In step C3-1, the vehicle main computer 21 reads out the steering amount and the vehicle speed. In step C3-2, the vehicle main computer 21 determines whether the read out steering amount is greater than a predetermined standard, and if it is greater (Yes), it then determines in step C3-3 whether the vehicle speed is greater than the predetermined standard (whether the vehicle is fast). If it is determined in step C3-3 that the vehicle speed is less than the predetermined standard and is not fast (No), it determines in step C3-4 that the turning request is large.

[0040] On the other hand, if the steering operation amount is smaller than the predetermined amount in step C3-2 (No), it is determined in step C3-5 that the turning request is small. Also, if the vehicle speed is equal to or greater than the predetermined standard and is high (Yes) in step C3-3, it is determined in step C3-5 that the turning request is small.

[0041] (Fig. 9) The control flow of the motor control system according to the present invention, which limits the torque difference calculated based on the outside air temperature and the vehicle speed, will be described. In step C5-1, the vehicle main computer 21 reads the vehicle speed detected by the wheel speed sensor 10 from the electric four-wheel drive control computer 22. In step C5-2, the vehicle main computer 21 reads the outside air temperature detected by the outside air temperature sensor 11 from the air conditioner control computer 24.

[0042] In step C5-3, the vehicle main computer 21 determines whether the read-out outside air temperature is equal to or higher than a predetermined threshold, and if it is equal to or higher than the threshold (Yes), in step C5-4, the vehicle main computer 21 determines whether the vehicle speed read by the wheel speed sensor 10 is equal to or lower than a threshold. Furthermore, in step C5-4, if the read-out vehicle speed is equal to or lower than the predetermined threshold (Yes), the vehicle main computer 21 reads out an upper limit value of the torque difference between the left and right rear wheels in step C5-5. The upper limit value of the torque difference will be described later with reference to FIG. 10. Then, in step C5-6, the torque difference between the left and right rear wheels is limited based on the read-out upper limit value of the torque difference between the left and right rear wheels.

[0043] On the other hand, if the outside air temperature is lower than the predetermined threshold in step C5-3 (No), the torque difference between the left and right rear wheels is not calculated in step C5-7. Also, if the vehicle speed is higher than the predetermined threshold in step C5-4 (No), the torque difference is not calculated in step C5-7.

[0044] In this way, when the vehicle speed is high or the road surface is likely to be frozen, the torque difference between the left and right wheels is not calculated because a large torque difference between them may cause slippage, and when the vehicle speed is slower than a predetermined value, the torque difference is limited and controlled by setting an upper limit value for the torque difference depending on the vehicle speed. Also, by being able to control the torque difference generated between the left and right wheels according to the vehicle speed in this way, more precise control can be achieved in the torque output request to the rear motor in the vehicle main computer 21 shown in steps C1-4 (FIG. 5), C2-4 (FIG. 6), and C4-4 (FIG. 7), improving the controllability of the vehicle and the vehicle stability in the medium speed range or higher, and contributing to the prevention of slippage.

[0045] (Figure 10) A graph showing the torque difference between the rear wheels according to the speed when the steering angle is constant and a characteristic diagram showing the limit of the torque difference will be described below. Note that the vertical axis represents the torque difference between the rear wheels, and the horizontal axis represents the driving speed.

[0046] As shown in Fig. 9, the present invention limits the torque difference within a range within an upper limit value 32 of the torque difference. When the vehicle speed transitions from a stopped state to a low speed, a large yaw moment is required, so the torque difference is made large. However, when the vehicle speed increases, there is a risk of the vehicle slipping, so in order to maintain vehicle stability, the limit on the torque difference relative to steering operation becomes greater, and the torque difference relative to steering operation is made small. When the vehicle speed is equal to or higher than a predetermined vehicle speed 31, the control of the torque difference is prohibited.

[0047] In this way, an upper limit is set for the maximum torque difference that is created according to the vehicle speed, and the torque difference is prevented from being created when the vehicle speed is equal to or greater than a certain value, thereby making it possible to maintain the stability of the vehicle.

[0048] (Fig. 11) The control flow of the motor control system for determining the priority order of torque requests according to the present invention will be described below. In step C6-1, the control request flag and the requested torque are read from the electric four-wheel drive control computer 22. In step C6-2, the control request flag and the requested torque are read from the vehicle main computer 21.

[0049] In step C6-3, it is determined whether or not there is a torque control request from the vehicle main computer 21. If there is a torque control request (Yes), in step C6-4, the rear motor is driven based on the torque request from the vehicle main computer 21 that is calculated taking into account the torque request from the electric four-wheel drive control computer 22.

[0050] If in step C6-3 there is no torque control request from the vehicle main computer 21 (No), in step C6-5 it is confirmed whether there is a torque control request from the electric four-wheel drive control computer 22. If in step C6-5 there is a torque control request from the electric four-wheel drive control computer 22 (Yes), in step C6-6 the rear motor is driven based on the requested torque read from the electric four-wheel drive control computer 22. If in step C6-5 there is no torque control request (No), in step C6-7 the rear motor is not driven.

[0051] According to the present invention, instead of providing steering devices (steering parts) for the left and right rear wheels, the rear wheels are steered according to the steering operation amount by the rear motors provided independently for the left and right wheels, and the torque for each of the left and right rear wheels is freely controlled, so that even if the number of parts is reduced and the weight is reduced, a torque difference is generated between the left and right wheels, a yaw moment is generated on the vehicle, and cornering performance is improved. Therefore, while realizing cost reduction, it is possible to realize small turning radius at low speeds and improve handling stability at medium and high speeds, and obtain the same functions as 4WS.

[0052] In addition, when the front wheels slip, driving force is generated at the rear wheels, improving driving stability. In addition, by generating a torque difference between the left and right wheels when the rear wheels are generating driving force, and generating regenerative torque at only one wheel when the rear wheels are not generating driving force, braking force can be obtained without using the brake device. In addition, the torque difference can be controlled by reducing it according to the vehicle speed. Therefore, since torque control, powering / regeneration, and forward / reverse rotation are possible with high precision, vehicle control can be performed with a wider degree of freedom, and the risk of breakdowns is also reduced.

[0053] In addition, just like a conventional 4WS in which the vehicle moves in the opposite phase at the entrance to a corner on its travel route to generate a yaw moment, and then when the vehicle enters a straight-ahead direction at the end of the corner, the wheels are controlled to the same phase to cancel out the generated yaw moment, the present invention also makes it possible to generate or cancel a yaw moment by using a torque difference.

[0054] According to the embodiment of the present invention described above, the following advantageous effects are achieved.

[0055] (1) The system includes a powertrain control device 23 that controls the torque for driving a powertrain connected to the front wheels of the vehicle via a transmission 3t based on the accelerator opening, a steering control device 25 that steers the front wheels based on the steering amount of the steering wheel 6, a rear wheel motor control device 20 that outputs torque commands to rear motors 2R, 2L provided on the left and right rear wheels of the vehicle to control the left and right rear wheels, and a vehicle main control device 21 that calculates the torque difference between the left and right rear wheels based on the steering amount and the accelerator opening, and the rear wheel motor control device 20 calculates the torque command to be output to the rear motors 2R, 2L based on the torque difference calculated by the vehicle main control device 21. In this way, a control system that realizes reduced risk of failure, weight reduction, and cost reduction can be provided.

[0056] (2) An electric four-wheel drive control device 22 is provided that detects the degree of slippage of the front wheels and outputs a torque output request to the rear motors 2R, 2L to the vehicle main control device 21 based on the degree of slippage. In this way, the rear wheels can be driven even if the front wheels slip, ensuring driving stability.

[0057] (3) When there is a torque output request from the electric four-wheel drive control device 22, the vehicle main control device 21 determines the torque distribution to each of the left and right rear wheels based on the calculated torque difference, and the rear wheel motor control device 20 outputs a torque command to the rear motors 2R, 2L based on the torque distribution determined by the vehicle main control device 21. In this manner, it is possible to realize fine control of the rear motors 2R, 2L corresponding to the drive request.

[0058] (4) When there is no torque output request from the electric four-wheel drive control device 22, the vehicle main control device 21 calculates a torque difference based on the steering amount and accelerator opening, and determines the magnitude of the vehicle turning request based on the steering amount and the vehicle speed, and when the magnitude of the turning request is greater than a predetermined standard, calculates a regenerative torque for one of the rear wheels and a powering torque for the other rear wheel based on the calculated torque difference, and when the magnitude of the turning request is smaller than the predetermined standard, calculates a regenerative torque for one of the rear wheels. In this way, vehicle stability at medium speeds and above is improved.

[0059] (5) The vehicle has an air conditioner control device 24 that acquires the outside air temperature of the vehicle, and the vehicle main control device 21 does not calculate the torque difference when the outside air temperature is lower than a predetermined threshold or the vehicle speed is higher than a predetermined threshold, and limits the torque difference according to the vehicle speed when the outside air temperature is equal to or higher than the predetermined threshold and the vehicle speed is equal to or lower than the predetermined threshold. In this way, more precise control can be achieved according to the external environment and the vehicle speed, improving the controllability of the vehicle and the vehicle stability at medium speeds and above, and contributing to the prevention of slipping.

[0060] The present invention is not limited to the above-mentioned embodiment, and various modifications and other configurations can be combined without departing from the spirit of the present invention. Furthermore, the present invention is not limited to those having all of the configurations described in the above-mentioned embodiment, and includes those in which some of the configurations are omitted. [Explanation of symbols]

[0061] FR Front right tire FL Front left tire RR Rear right tire RL Rear left tire 2R Right rear wheel motor 2L Left rear wheel motor 3e Engine 3t Transmission 3p propeller shaft 4a Steering actuator 4l Steering link mechanism 5. Air Compressor 6. Steering 7. Accelerator pedal 7s Accelerator opening sensor 10FR Right front wheel speed sensor 10FL Left front wheel speed sensor 10RR Right rear wheel speed sensor 10RL Left rear wheel speed sensor 11 Outside Air Temperature Sensor 12 Steering angle sensor 20 Rear wheel motor control computer 21 Vehicle main computer 22 Electric four-wheel drive control computer 23 Powertrain control computer 24 Air conditioner control computer 25 Steering control computer 30 In-vehicle communication network 31 Prescribed vehicle speed 32 Upper limit of torque difference 100 vehicles

Claims

1. a powertrain control device that controls a torque for driving a powertrain connected to front wheels of a vehicle via a transmission, based on an accelerator opening degree; a steering control device that steers the front wheels based on a steering amount; a rear wheel motor control device that outputs a torque command to a rear motor provided on each of the left and right rear wheels of the vehicle to control the left and right rear wheels; a vehicle main control device that calculates a torque difference between the left and right rear wheels based on the steering amount and the accelerator opening degree, The rear wheel motor control device calculates the torque command to be output to the rear motor based on the torque difference calculated by the vehicle main control device. Control system.

2. 2. The control system of claim 1, an electric four-wheel drive control device that detects a slippage of the front wheels and outputs a torque output request to the rear motor to the vehicle main control device based on the slippage; Control system.

3. 3. The control system of claim 2, when there is a torque output request from the electric four-wheel drive control device, the vehicle main control device determines a torque distribution to each of the left and right rear wheels based on the calculated torque difference; The rear wheel motor control device outputs the torque command to the rear motor based on the torque distribution determined by the vehicle main control device. Control system.

4. 3. The control system of claim 2, when there is no torque output request from the electric four-wheel drive control device, the vehicle main control device calculates the torque difference based on the steering amount and the accelerator opening degree, and determines the magnitude of a turning request for the vehicle based on the steering amount and a vehicle speed of the vehicle; When the magnitude of the turning request is greater than a predetermined reference value, a regenerative torque is calculated for one of the rear wheels and a powering torque is calculated for the other rear wheel based on the calculated torque difference; When the magnitude of the turning request is smaller than a predetermined reference value, the regenerative torque is calculated for the one of the rear wheels. Control system.

5. 2. The control system of claim 1, an air conditioner control device that acquires an outside air temperature of the vehicle; The vehicle main control device does not calculate the torque difference when the outside air temperature is lower than a predetermined threshold or the vehicle speed is higher than a predetermined threshold, and limits the torque difference in accordance with the vehicle speed when the outside air temperature is equal to or higher than a predetermined threshold and the vehicle speed is equal to or lower than the predetermined threshold. Control system.

Images