Vehicle control system

Abstract

The invention provides a vehicle control system capable of suppressing insufficiency of braking force and instability of vehicle behavior when a slipping state of wheels is eliminated. A vehicle control system is provided with an electric brake control unit for controlling a hydraulic pressure generation unit, a behavior control unit for controlling each brake mechanism, a front motor control unit and a rear motor control unit for controlling each rotary electric machine, and an integrated control unit. When the front motor control unit executes regenerative braking, the behavior control unit cuts off the flow of the working medium of the hydraulic pressure generation unit with respect to each of the front brake mechanisms when a slip state occurs at the front wheels. The electric brake control unit increases the pressure of the pressure medium in the hydraulic pressure generation unit compared to a case where a slip state does not occur at the front wheels.

Description

Technical Field

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

[0002] In recent years, efforts to provide sustainable transportation systems that take into account vulnerable people such as the elderly, the disabled, and children among traffic participants have been active. To achieve this, research and development efforts are focused on further improving traffic safety and convenience through development related to vehicle behavior stability.

[0003] Conventionally, there is known a control device that predicts the start of antilock brake control and increases the friction braking force and reduces the regenerative braking force in advance to suppress a sudden decrease in deceleration caused by a response delay in the friction braking force (see, for example, Patent Document 1 below).

[0004] Patent Document 1: Japanese Patent Application Laid-Open No. 2012-35840 Summary of the invention

[0005] In addition, in terms of vehicle behavior stability, when wheel slip occurs during deceleration by regenerative braking, a problem is to suppress insufficient braking force and unstable vehicle behavior and eliminate the slipping state.

[0006] For example, the control device of the prior art controls the friction braking force and the regenerative braking force before the anti-lock brake control starts to work, but it is difficult to accurately predict the vehicle behavior that changes according to the driving road surface and the braking state, and it may not be possible to ensure the appropriate braking force. For example, when the regenerative braking force is replaced by the friction braking force with the operation of the anti-lock brake control, the braking force may be insufficient due to the pressure fluctuation caused by the opening and closing of the valve in the hydraulic circuit of the friction brake.

[0007] The solution involved in the present invention is made in consideration of such a situation, and its object is to provide a vehicle control system that can suppress the lack of braking force and the instability of vehicle behavior when eliminating the slip state at the wheel, thereby contributing to the development of a sustainable transportation system.

[0008] In order to solve the above-mentioned problems and achieve the related objects, the present invention adopts the following means.

[0009] (1): A vehicle control system involved in one embodiment of the present invention comprises: a rotating motor control unit, which controls the operation of the rotating motor that transmits and receives torque to and from a specified wheel; and a friction brake control unit, which controls the operation of a pressure system, which drives the friction brake mechanism of multiple wheels including the specified wheel through a pressure medium, and when the specified wheel slips during regenerative braking by the rotating motor control unit, the friction brake control unit cuts off the flow of the pressure medium relative to the friction brake mechanism of the specified wheel, and increases the pressure of the pressure medium compared to a case where the slip does not occur.

[0010] (2): Based on the above scheme (1), it may also be that, during the period when the friction brake control unit cuts off the flow of the pressure medium relative to the friction brake mechanism of the specified wheel when a slipping state occurs at the specified wheel, the pressure of the pressure medium is set corresponding to the friction braking torque obtained by multiplying the regenerative braking torque reduced by the rotating motor control unit by a specified coefficient, thereby increasing the pressure of the pressure medium compared to a case where the slipping state does not occur.

[0011] (3): Based on the above scheme (1) or (2), the friction brake control unit may also terminate the control of increasing the pressure of the pressure medium compared to a case where the slip state does not occur after a specified time when the flow of the pressure medium to the friction brake mechanism relative to the specified wheel is cut off.

[0012] According to the above scheme (1), the friction brake control unit cuts off the flow of pressure medium to the friction brake mechanism of the specified wheel, thereby promoting the elimination of the slip state of the specified wheel. The friction brake control unit increases the pressure of the pressure medium flowing to the friction brake mechanism of other wheels other than the specified wheel compared to the case where the slip state does not occur, thereby suppressing the lack of friction braking force of the entire vehicle. The friction brake control unit can suppress the lack of braking force and the instability of vehicle behavior when eliminating the slip state at the specified wheel.

[0013] In the case of the above scheme (2), the rotating electrical machine control unit replaces the regenerative braking torque at the specified wheel with the friction braking torque at the wheels other than the specified wheel, thereby promoting the elimination of the slip state of the specified wheel. When replacing the friction braking torque, the friction braking control unit increases the pressure of the pressure medium in order to include the insufficient friction braking torque due to the flow cutoff of the pressure medium relative to the friction braking mechanism of the specified wheel, thereby suppressing the insufficient braking force (the sum of the friction braking force and the regenerative braking force) of the entire vehicle.

[0014] In the case of the above scheme (3), the friction brake control unit releases the flow cutoff of the pressure medium relative to the friction brake mechanism of the specified wheel when the slip state of the specified wheel is eliminated, thereby ending the control of increasing the pressure of the pressure medium, thereby suppressing the excessive friction braking force of the entire vehicle. The friction brake control unit makes the pressure increase of the pressure medium become zero after a specified time, thereby suppressing the rapid change of the friction braking force and the instability of the vehicle behavior. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a block diagram of a vehicle control system in an embodiment of the present invention.

[0016] Figure 2 It is a block diagram showing the functional configuration of a vehicle control system in the embodiment of the present invention.

[0017] Figure 3 It is a block diagram of a hydraulic system in a vehicle control system according to an embodiment of the present invention.

[0018] Figure 4 This is a diagram showing an example of the correspondence relationship among the vehicle speed, the valve closing flag, the braking force, the pressure of the hydraulic system, and the braking torque in the vehicle control system according to the embodiment of the present invention.

[0019] Figure 5 1 is a diagram showing an example of the correspondence relationship between the valve closing flag and the pressure of the hydraulic system in the vehicle control system according to the embodiment of the present invention and the comparative example. DETAILED DESCRIPTION

[0020] Hereinafter, a vehicle control system according to an embodiment of the present invention will be described with reference to the drawings.

[0021] Figure 1 It is a block diagram of the vehicle control system 10 in the embodiment. Figure 2 : is a block diagram showing the functional structure of the vehicle control system 10 in the embodiment.

[0022] The vehicle control system 10 of the embodiment is mounted on an electric vehicle (vehicle) such as an electric vehicle, a hybrid vehicle, and a fuel cell vehicle. An electric vehicle is driven by a battery as a power source. A hybrid vehicle is driven by a battery and an internal combustion engine as a power source. A fuel cell vehicle is driven by a fuel cell as a power source.

[0023] The vehicle equipped with the vehicle control system 10 is, for example, a front-wheel drive vehicle having a rotating motor that generates power for the front wheels, a rear-wheel drive vehicle having a rotating motor that generates power for the rear wheels, or an all-wheel drive vehicle having a rotating motor that generates power for the front and rear wheels respectively.

[0024] like Figure 1 and Figure 2 As shown, the vehicle 1 equipped with the vehicle control system 10 has, for example, a front rotating motor (MF) 11a and a rear rotating motor (MR) 11b, a front differential device 13a and a rear differential device 13b, a first front brake mechanism 15FL and a second front brake mechanism 15FR, a first rear brake mechanism 15RL and a second rear brake mechanism 15RR, and a processing device 17.

[0025] The front rotary motor 11a transfers torque to and from the left and right front wheels Fr, for example, via the front differential device 13a. The rear rotary motor 11b transfers torque to and from the left and right rear wheels Rr, for example, via the rear differential device 13b. Each rotary motor 11a, 11b is, for example, a three-phase AC brushless DC motor. Each rotary motor 11a, 11b generates a driving torque for each wheel Fr, Rr by performing a power running operation using the electric power supplied from the electric power conversion device, etc. Each rotary motor 11a, 11b generates a generated electric power and generates a regenerative braking torque for each front wheel Fr and each rear wheel Rr by performing a regenerative operation using the rotary power input from the front wheels Fr and the rear wheels Rr.

[0026] The front differential device 13a connects the front rotary motor 11a to the left and right front wheels Fr, for example. The rear differential device 13b connects the rear rotary motor 11b to the left and right rear wheels Rr, for example. Each differential device 13a, 13b is, for example, a bevel gear type differential mechanism, and is a so-called open differential without a differential limiting mechanism.

[0027] The first front brake mechanism 15FL and the second front brake mechanism 15FR are, for example, friction brake mechanisms provided on the left and right front wheels Fr, respectively. The first rear brake mechanism 15RL and the second rear brake mechanism 15RR are, for example, friction brake mechanisms provided on the left and right rear wheels Rr, respectively. Each brake mechanism 15FL, 15FR, 15RL, 15RR includes a disc brake or a drum brake connected to a hydraulic pressure generating unit 51 described later, for example, by oil pressure. Each brake mechanism 15FL, 15FR, 15RL, 15RR performs friction braking on each front wheel Fr and each rear wheel Rr, for example, by the hydraulic pressure generated by the actuator of the hydraulic pressure generating unit 51 according to the operation of the brake operating member by the operator.

[0028] The processing device 17 includes, for example, an electric brake control unit 21 , a behavior control unit 23 , a front motor control unit 25 a , a rear motor control unit 25 b , and a comprehensive control unit 27 .

[0029] Each control unit 21, 23, 25a, 25b, 27 is a software function unit that performs its function by executing a predetermined program by a processor such as a CPU (Central Processing Unit). The software function unit is an ECU having an electronic circuit such as a processor such as a CPU, a ROM (Read Only Memory) for storing programs, a RAM (Random Access Memory) for temporarily storing data, and a timer. At least a part of each control unit 21, 23, 25a, 25b, 27 may also be an integrated circuit such as an LSI (Large Scale Integration).

[0030] The vehicle control system 10 according to the embodiment includes, for example, a processing device 17 and various sensors mounted on the vehicle 1 .

[0031] The processing device 17 obtains signals of detection values ​​outputted from various sensors of the vehicle 1, and comprehensively controls the rotating electrical machines 11a, 11b and the brake mechanisms 15FL, 15FR, 15RL, 15RR. The various sensors include, for example, the operation amount sensor 31, the rotation sensor 33, the acceleration sensor 35, the wheel speed sensor 37, the current sensor 39, the voltage sensor 41, and the temperature sensor 43.

[0032] The operation amount sensor 31 includes, for example, a brake operation sensor for detecting whether the operator operates the brake operating member and the amount of operation of the brake operating member by the operator, and a throttle operation sensor for detecting whether the operator operates the throttle operating member and the amount of operation of the throttle operating member by the operator. The rotation sensor 33 detects the rotation angle of each rotating motor 11a, 11b. The acceleration sensor 35 detects the acceleration of the vehicle 1. The wheel speed sensor 37 detects the rotation speed (wheel speed) of each front wheel Fr and each rear wheel Rr (each wheel). The current sensor 39, the voltage sensor 41, and the temperature sensor 43 each detect the current, voltage, and temperature of each rotating motor 11a, 11b and a storage device such as a battery that transfers power to and from each rotating motor 11a, 11b.

[0033] The electric brake control unit 21 controls, for example, the operation of the hydraulic pressure generating unit 51 to generate hydraulic pressure for each of the brake mechanisms 15FL, 15FR, 15RL, and 15RR.

[0034] The behavior control unit 23 controls the friction brakes generated by the brake mechanisms 15FL, 15FR, 15RL, and 15RR based on the hydraulic pressure generated by the control of the electric brake control unit 21, for example, in order to suppress the sudden change of the behavior of the vehicle 1 and stabilize the posture. The behavior control unit 23 performs, for example, anti-lock control to prevent wheel lock during braking, traction control to prevent wheel slip (slip at each wheel) during acceleration and deceleration, and control to suppress lateral slip during turning. The behavior control unit 23 obtains the detection value signals output from the acceleration sensor 35 and the wheel speed sensor 37, for example, and estimates the speed of the vehicle 1 (body speed).

[0035] The front motor control unit 25a and the rear motor control unit 25b are each provided with a power conversion device connected to a power source such as a power storage device mounted on the vehicle 1. Each motor control unit 25a, 25b controls the power transfer of each of the front rotary motor 11a and the rear rotary motor 11b via a power conversion device constituted by, for example, a plurality of switching elements. Each motor control unit 25a, 25b generates a rotational driving force by sequentially reversing the power supply to the three phases during the power running operation of each rotary motor 11a, 11b. Each motor control unit 25a, 25b generates a rotational braking force by converting the AC power input from the three phases into DC power through the switching operation of each phase synchronized with the rotation during the regenerative operation of each rotary motor 11a, 11b.

[0036] Figure 3 1 is a block diagram of the hydraulic system 50 in the vehicle control system 10 according to the embodiment.

[0037] like Figure 3 As shown, the hydraulic system 50 includes, for example, a hydraulic pressure generating unit 51 , a medium flow path 53 , first and second front and rear valves 55 a and 55 b , second and second front and rear valves 57 a and 57 b , a reservoir tank 59 , a check valve 61 , and a pump 63 .

[0038] The hydraulic pressure generating unit 51 includes, for example, a hydraulic cylinder such as a master cylinder that generates hydraulic pressure (master pressure), and an actuator such as an electric motor that is a power source of the hydraulic cylinder.

[0039] The medium flow path 53 is a flow path for a working medium (pressure medium) that transmits power such as hydraulic oil.

[0040] The first front valve 55a and the first rear valve 55b are, for example, directional control valves, etc. Each valve 55a, 55b is arranged in the medium flow path 53 between the hydraulic pressure generating unit 51 and each brake mechanism 15FL, 15FR, 15RL, 15RR. Each valve 55a, 55b, for example, switches between the flow and cutoff of the working medium relative to each brake mechanism 15FL, 15FR, 15RL, 15RR.

[0041] The second front valve 57a and the second rear valve 57b are, for example, directional control valves, etc. Each valve 57a, 57b is arranged in the medium flow path 53 between the first front valve 55a, the first rear valve 55b and the storage tank 59. Each valve 57a, 57b switches between, for example, the flow and cutoff of the working medium with respect to the storage tank 59.

[0042] The storage tank 59 stores the working medium.

[0043] The check valve 61 is disposed in the medium flow path 53 between the reservoir 59 and the pump 63. The check valve 61 allows the working medium to flow from the reservoir 59 to the pump 63, and prohibits the working medium from flowing back from the pump 63 to the reservoir 59.

[0044] The pump 63 is disposed in the medium flow path 53 between the hydraulic pressure generating unit 51 and the first front valve 55a and the first rear valve 55b. The pump 63 sends the working medium toward the hydraulic pressure generating unit 51.

[0045] In the hydraulic system 50, for example, when the first front valve 55a and the first rear valve 55b are in an open state, the working medium flows in parallel from the hydraulic pressure generating unit 51 to each brake mechanism 15FL, 15FR, 15RL, 15RR. For example, if each valve 55a, 55b is in an open state, the pressure of the working medium (front pressure) acting on each front brake mechanism 15FL, 15FR and the pressure of the working medium (rear pressure) acting on each rear brake mechanism 15RL, 15RR become the same according to the pressure (main pressure) of the working medium in the hydraulic pressure generating unit 51. In the state where the same pressure acts, the friction braking force based on each front brake mechanism 15FL, 15FR and the friction braking force based on each rear brake mechanism 15RL, 15RR are preset to have a predetermined front-to-rear ratio according to, for example, the size and friction material of each brake mechanism 15FL, 15FR, 15RL, 15RR.

[0046] Hereinafter, an operation example of the vehicle control system 10 in the embodiment will be described.

[0047] Figure 4 1 is a diagram showing an example of the correspondence relationship among the speed of the vehicle 1, the valve closing flag, the braking force, the pressure of the hydraulic system, and the braking torque in the vehicle control system 10 according to the embodiment. Figure 4 In the example shown, the vehicle 1 is in a front-wheel drive state in which the front rotating electric machine 11 a generates torque (driving torque and regenerative braking torque) in the left and right front wheels Fr.

[0048] For example, when the vehicle 1 decelerates after time t1 , the integrated control unit 27 obtains the braking force (required braking force) of the vehicle 1 requested by the driver based on the driver's operation of the accelerator and brake operating elements related to deceleration of the vehicle 1 .

[0049] First, for example, during the period from time t1 to time t2 when the braking force is required to increase due to the driver's brake operation, the integrated control unit 27 increases the regenerative braking force of the front rotary electric machine 11a via the front motor control unit 25a, thereby generating a braking force equivalent to the required braking force.

[0050] Next, for example, during the period from time t2 to time t3 when the braking force is required to be increased due to the driver's braking operation, the integrated control unit 27 increases the line pressure of the hydraulic system 50 through the electric brake control unit 21 and the behavior control unit 23, thereby increasing the friction braking force of each brake mechanism 15FL, 15FR, 15RL, 15RR. The electric brake control unit 21 and the behavior control unit 23, for example, open the valves 55a and 55b of the hydraulic system 50 and increase the line pressure of the hydraulic pressure generating unit 51, thereby increasing the pressure of the working medium acting on each brake mechanism 15FL, 15FR, 15RL, 15RR. For example, when the valves 55a and 55b are in the open state, the pressure of the working medium (front pressure) acting on each front brake mechanism 15FL, 15FR and the pressure of the working medium (rear pressure) acting on each rear brake mechanism 15RL, 15RR are equal to the line pressure generated by the hydraulic pressure generating unit 51. The integrated control unit 27 generates a braking force corresponding to the required braking force using the regenerative braking force of the front rotary electric machine 11 a and the friction braking force of each brake mechanism 15FL, 15FR, 15RL, and 15RR.

[0051] Next, when the braking force is required to be constant, for example as after time t3, and when the slip state of the front wheel Fr and the rear wheel Rr is not detected as in the period until time t4, the integrated control unit 27 generates a braking force equivalent to the required braking force by maintaining the regenerative braking force of the front rotating motor 11a and the friction braking force of each brake mechanism 15FL, 15FR, 15RL, and 15RR constant.

[0052] Next, when the behavior control unit 23 detects the slipping state of the front wheel Fr, for example, due to the change of the driving road to a low-friction road, etc., and the wheel speed at the front wheel Fr is less than a predetermined threshold value corresponding to the vehicle body speed, the anti-lock control is started. The behavior control unit 23, for example, switches the valve closing flag of the hydraulic system 50 to the first front valve 55a from "0" in the open state to "1" in the closed state, thereby cutting off the flow of the working medium to each front brake mechanism 15FL, 15FR. According to the closed state of the first front valve 55a, the pressure (front pressure) of the working medium acting on each front brake mechanism 15FL, 15FR becomes at least less than the main pressure at time t4, for example, changes to be constant or changes with a decreasing tendency from time t4. On the other hand, the first rear valve 55b is maintained in an open state, so that the pressure (rear pressure) of the working medium acting on each rear brake mechanism 15RL, 15RR is always equal to the main pressure.

[0053] Furthermore, for example, from time t4 to time t5 when the front wheel Fr continues to slip, the integrated control unit 27 changes the regenerative braking force of the front rotary electric machine 11a to a decreasing trend and changes the line pressure of the hydraulic pressure generating unit 51 to an increasing trend via the front motor control unit 25a and the electric brake control unit 21, thereby changing the pressure of the working medium (rear pressure = line pressure) acting on each rear brake mechanism 15RL, 15RR to an increasing trend. The electric brake control unit 21 increases the line pressure of the hydraulic pressure generating unit 51, for example, compared with the case where the friction braking force is increased in accordance with the reduction of the regenerative braking force and the required braking force in a state where the wheels do not slip. For example, the electric brake control unit 21 increases the line pressure of the hydraulic pressure generating unit 51 by a predetermined increase amount PU, by further increasing the friction braking force on the basis of the increase amount PS of the line pressure corresponding to the case where the regenerative braking force at the front wheel Fr is replaced by the friction braking force. Figure 4 The front pressure PP shown is, for example, the amount of reduction when the front pressure is reduced from time t4 according to the closed state of the first front valve 55 a .

[0054] The prescribed increase amount PU of the line pressure includes at least an increase amount for compensating the increase amount PS of the line pressure on the side of each rear brake mechanism 15RL, 15RR for the amount not acting on each front brake mechanism 15FL, 15FR due to the closed state of the first front valve 55a.

[0055] The electric brake control unit 21 sets the braking force (second braking force) obtained by adding the prescribed braking force to the braking force (first braking force) obtained by subtracting the regenerative braking force from the required braking force as the friction braking force. The first braking force is, for example, the total friction braking force set when the regenerative braking force is replaced by the friction braking force in a state where no slip of each wheel occurs. The second braking force is, for example, the total friction braking force set when the regenerative braking force is replaced by the friction braking force in a state where slip of the drive wheel (for example, the front wheel Fr in the front-wheel drive) occurs. The prescribed braking force is the braking force corresponding to the prescribed increase PU of the main pressure mentioned above and the raised friction braking torque TrU described later.

[0056] When the electric brake control unit 21 replaces the regenerative braking force with the friction braking force, for example, after time t4, the increase in the friction braking torque corresponding to the decrease in the regenerative braking torque is set as the replacement friction braking torque TrS. The electric brake control unit 21, for example, adds the replacement friction braking torque TrS to the increased friction braking torque TrU corresponding to the above-mentioned prescribed braking force (the total increase in the friction braking torque) as the total increased friction braking torque TrT (=TrS+TrU). The electric brake control unit 21, for example, multiplies the replacement friction braking torque TrS by a prescribed coefficient as the total increased friction braking torque TrT. The prescribed coefficient is, for example, the reciprocal of a prescribed rear braking coefficient k (0<k<1) set for each rear brake mechanism 15RL, 15RR in the case of front-wheel drive. That is, the prescribed rear braking coefficient k represents the ratio of the replacement friction braking torque TrS in the total increased friction braking torque TrT when the first front valve 55a is in the closed state. For example, the replacement friction braking torque TrS, the increase friction braking torque TrU, the total increase friction braking torque TrT (=TrU+TrS), and the predetermined rear braking coefficient k have a corresponding relationship expressed by the following mathematical formula.

[0057] Total increased friction braking torque TrT = replacement friction braking torque TrS / k

[0058] Raising friction braking torque TrU = replacing friction braking torque TrS × (1-k) / k

[0059] For example, during the period from time t4 to time t5, the replacement friction braking torque TrS is equal to the regenerative braking torque reduction amount (= Tra - Trb) from the regenerative braking torque Tra at time t4 to the regenerative braking torque Trb at time t5. The increase friction braking torque TrU is equal to the total braking torque increase amount (= Trd - Trc) from the total braking torque (= regenerative braking torque + friction braking torque = required braking torque) Trc at time t4 to the total braking torque Trd (= regenerative braking torque + friction braking torque) at time t5.

[0060] Next, for example, at time t5, when the wheel speed at the front wheel Fr becomes equal to or higher than a predetermined threshold value corresponding to the vehicle body speed due to the cutoff of the flow of the working medium to each front brake mechanism 15FL, 15FR and the reduction of the regenerative braking force, and thus the behavior control unit 23 detects that the slip state of the front wheel Fr has been eliminated, the anti-lock control is stopped. For example, the behavior control unit 23 cancels the cutoff of the flow of the working medium to each front brake mechanism 15FL, 15FR by switching the valve closing flag of the first front valve 55a of the hydraulic system 50 from "1" in the closed state to "0" in the open state. According to the open state of the first front valve 55a, the pressure (front pressure) of the working medium acting on each front brake mechanism 15FL, 15FR increases toward the main pressure. On the other hand, the first rear valve 55b is maintained in the open state, so that the pressure (rear pressure) of the working medium acting on each rear brake mechanism 15RL, 15RR is equal to the main pressure.

[0061] When the first front valve 55a is switched from the closed state to the open state, the working medium is absorbed toward the front brake mechanisms 15FL and 15FR as compared to the rear brake mechanisms 15RL and 15RR of the first rear valve 55b which is maintained in the open state, and the main pressure (= rear pressure) is temporarily reduced as the front pressure increases. Moreover, after an appropriate period of time, the main pressure (= rear pressure) and the front pressure become the same at a predetermined equilibrium pressure.

[0062] As described above, the electric brake control unit 21 increases the main pressure of the hydraulic pressure generating unit 51 by a predetermined increase amount PU in advance, for example, during the period from time t4 to time t5, thereby preventing the friction braking force from being insufficient relative to the required braking force even if the main pressure temporarily decreases, for example after time t5.

[0063] Furthermore, the electric brake control unit 21 gradually decreases the predetermined increase amount PU toward zero until, for example, time t6 in order to prevent the friction braking force from being excessive relative to the required braking force after the line pressure is temporarily reduced after, for example, time t5. For example, the predetermined time from time t5 to time t6 is set to be at least the time required to make the line pressure (= rear pressure) and the front pressure equal at a predetermined balance pressure.

[0064] The electric brake control unit 21 decreases the predetermined increase amount PU of the line pressure toward zero from time t5 to time t6 , for example, thereby decreasing the build-up friction braking torque TrU corresponding to the above-mentioned predetermined braking force toward zero.

[0065] Next, for example, from time t6 to time t7, the integrated control unit 27 switches the friction braking force between the front wheel Fr and the rear wheel Rr before the regenerative braking force at the front wheel Fr becomes zero, and ensures the required braking force only by the friction braking force.

[0066] Figure 5 1 is a diagram showing an example of the correspondence relationship between the valve closing flag and the pressure of the hydraulic system 50 in the vehicle control system 10 of the embodiment and the comparative example.

[0067] Figure 5 In the illustrated embodiment and comparative example, the anti-lock control is executed from time t4 to time t5, for example, and after the first front valve 55a of the hydraulic system 50 is closed, the regenerative braking force at the front wheel Fr is replaced by the friction braking force.

[0068] The embodiment sets the increase PS of the line pressure corresponding to the replacement of the regenerative braking force with the friction braking force after the time t4 as described above, and compensates the predetermined increase PU of the line pressure not acting on the front wheel Fr at the rear wheel Rr. The comparative example is a case where the predetermined increase PU of the line pressure is not set.

[0069] In each of the embodiment and the comparative example, when the first front valve 55a of the hydraulic system 50 is switched from the closed state to the open state due to the stop of the antilock control as after time t5, the line pressure (=rear pressure) temporarily decreases as the front pressure increases.

[0070] In the comparative example, the line pressure of the hydraulic pressure generating unit 51 is not increased by the predetermined increase amount PU in advance, and thus, due to the temporary decrease in the line pressure after time t5, for example, the friction braking force becomes insufficient relative to the required braking force. For example, due to the decrease in the friction braking force corresponding to the decrease amount PD of the line pressure in the comparative example, the friction braking force (=required braking force-regenerative braking force) required for the required braking force can no longer be ensured.

[0071] In contrast, in the embodiment, the line pressure of the hydraulic pressure generating unit 51 is increased in advance by a predetermined increase amount PU, thereby ensuring the line pressure required for obtaining the friction braking force (= required braking force - regenerative braking force) required for the required braking force even if the line pressure temporarily decreases after, for example, time t5.

[0072] As described above, according to the vehicle control system 10 of the embodiment, when a slipping state occurs at the front wheel Fr performing regenerative braking, the behavior control unit 23 cuts off the flow of the working medium to each front brake mechanism 15FL, 15FR, and replaces the regenerative braking torque at the front wheel Fr with the friction braking torque, thereby promoting the elimination of the slipping state. The electric brake control unit 21 increases the pressure (main pressure) of the working medium flowing to each rear brake mechanism 15RL, 15RR compared to the case where the slipping state does not occur, thereby suppressing the insufficient friction braking force of the entire vehicle. The electric brake control unit 21 sets a predetermined increase amount PU of the main pressure, thereby suppressing the insufficient braking force and the instability of the vehicle behavior when eliminating the slipping state at the front wheel Fr.

[0073] The integrated control unit 27 can promote the elimination of the slipping state of the front wheel Fr by replacing the regenerative braking torque at the front wheel Fr with the friction braking torque. The electric brake control unit 21 sets the increase amount PS of the main pressure corresponding to the replacement to compensate for the amount that does not act on the front wheel Fr due to the closed state of the first front valve 55a at the rear wheel Rr as the prescribed increase amount PU of the main pressure, which can suppress the shortage of the braking force (the sum of the friction braking force and the regenerative braking force) of the entire vehicle.

[0074] The electric brake control unit 21 responds to a temporary drop in line pressure when the first front valve 55a is switched to the open state when the slip state at the front wheel Fr is resolved by the predetermined increase amount PU of the line pressure, thereby suppressing the insufficiency of the friction braking force and the comprehensive braking force of the entire vehicle.

[0075] When the slip state at the front wheel Fr is resolved, the electric brake control unit 21 reduces the predetermined increase amount PU of the line pressure toward zero within a predetermined time, thereby suppressing excessive friction braking force of the entire vehicle and suppressing abrupt changes in friction braking force and instability of vehicle behavior.

[0076] (Variation Example)

[0077] The following describes a modification of the embodiment. The same reference numerals are used for the same parts as those in the above-mentioned embodiment, and the description thereof will be omitted or simplified.

[0078] In the above-mentioned embodiments, for example Figure 4 As shown in the example, the vehicle 1 is in a front-wheel drive state where the front rotating motor 11a generates torque (driving torque and regenerative braking torque) for the left and right front wheels Fr, but the present invention is not limited thereto. For example, the vehicle 1 may be in a rear-wheel drive state where the rear rotating motor 11b generates torque (driving torque and regenerative braking torque) for the left and right rear wheels Rr, or in an all-wheel drive state where the rotating motors 11a, 11b, etc. generate torque for all wheels.

[0079] For example, in the case of rear-wheel drive, when the rear wheel Rr is in a slipping state, the behavior control unit 23 switches the first rear valve 55b of the hydraulic system 50 from an open state to a closed state by executing the anti-lock control, thereby cutting off the flow of the working medium to each rear brake mechanism 15RL, 15RR. Furthermore, the integrated control unit 27 changes the regenerative braking force of the rear rotary motor 11b to a decreasing tendency and changes the main pressure of the hydraulic pressure generating unit 51 to an increasing tendency during, for example, the period during which the rear wheel Rr is in a slipping state, thereby changing the pressure of the working medium (front pressure = main pressure) acting on each front brake mechanism 15FL, 15FR to an increasing tendency.

[0080] For example, in the case of rear-wheel drive, the predetermined coefficient multiplied by the replacement friction braking torque TrS in order to set the total increase friction braking torque TrT is the reciprocal of the predetermined front braking coefficient h set for each front brake mechanism 15FL, 15FR. The predetermined front braking coefficient h is, for example, converted by the predetermined rear braking coefficient k in the embodiment to become h=1-k. For example, when the first rear valve 55b is in the closed state, the replacement friction braking torque TrS, the increase friction braking torque TrU, the total increase friction braking torque TrT (=TrU+TrS) and the predetermined front braking coefficient h (=1-k) have a corresponding relationship expressed by the following mathematical formula.

[0081] Total increased friction braking torque TrT = replacement friction braking torque TrS / (1-k)

[0082] Raising friction brake torque TrU = replacement friction brake torque TrS × k / (1-k)

[0083] In the above-mentioned embodiment, the vehicle 1 includes the front rotary motor 11a connected to the left and right front wheels Fr, and the rear rotary motor 11b connected to the left and right rear wheels Rr, but the present invention is not limited thereto. For example, each wheel may be equipped with a rotary motor alone, or a suitable combination of multiple wheels may be equipped with a rotary motor alone.

[0084] In the above-mentioned embodiment, the prescribed increase amount PU of the line pressure is set as the increase amount PS of the line pressure corresponding to the case where the regenerative braking force is replaced by the friction braking force to compensate the amount that does not act on the front wheel Fr due to the closed state of the first front valve 55a at the rear wheel Rr, but it is not limited to this. For example, it is also possible that the behavior control unit 23 further includes the increase amount for compensating the reduced amount PP of the front pressure at the rear wheel Rr in the prescribed increase amount PU. For example, in the case of rear-wheel drive or all-wheel drive, the front wheel Fr and the rear wheel Rr may be read interchangeably.

[0085] The embodiments of the present invention are provided as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, and changes can be made without departing from the scope of the invention. These embodiments and their variations are included in the invention and its equivalent scope as they are included in the scope and purpose of the invention.

Claims

1. A vehicle control system, wherein: The vehicle control system comprises: a rotating electric machine control unit that controls the operation of the rotating electric machine that transmits and receives torque to and from a predetermined wheel; and a friction brake control unit that controls the operation of a pressure system that drives the friction brake mechanisms of a plurality of wheels including the predetermined wheel through a pressure medium, When a slip state occurs at the specified wheel during regenerative braking performed by the rotating electric machine control unit, the friction brake control unit cuts off the flow of the pressure medium to the friction brake mechanism of the specified wheel and increases the pressure of the pressure medium compared to a case where the slip state does not occur.

2. The vehicle control system according to claim 1, wherein: During the period when the friction brake control unit cuts off the flow of the pressure medium relative to the friction brake mechanism of the specified wheel when a slip state occurs at the specified wheel, the pressure of the pressure medium is set corresponding to the friction brake torque obtained by multiplying the regenerative braking torque reduced by the rotating motor control unit by a specified coefficient, thereby increasing the pressure of the pressure medium compared to a case where the slip state does not occur.

3. The vehicle control system according to claim 1 or 2, wherein: The friction brake control unit terminates control for increasing the pressure of the pressure medium compared to a case where the slip state does not occur after a predetermined time when the interruption of the flow of the pressure medium to the friction brake mechanism of the predetermined wheel is released.

Images