JPH09303433A - Hydraulic brake device for electric vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a miniature and inexpensive decompressing means variable in decompression quantity. SOLUTION: The spring 28 of a relief valve 26 is installed between a valve element 27 and a control piston 31, for making the decompression quantity of the relief valve 26 variable. The control piston 31 is pushed in a direction for closing the valve element 27 via a spring 28, by the pressure difference between a control fluid pressure chamber 32 and wheel brakes 17 and 18. The pressure difference action area for the control piston 31 is set slightly larger than that of the valve element 27. A control fluid pressure lead in path 33 for leading control fluid pressure into a control fluid pressure chamber 32 from a master cylinder 22, and an opening/closing solenoid valve 34 for increasing control fluid pressure, normally opened, for opening/closing the control fluid pressure lead in path 33, are installed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The invention of the present application relates to a hydraulic brake device for an electric vehicle equipped with a regenerative braking device, and more particularly to a hydraulic brake device corresponding to a brake operating force in order to enhance regenerative efficiency during vehicle braking. The present invention relates to a hydraulic brake device for an electric vehicle in which a pressure reducing means is installed in a hydraulic pressure transmission path between a hydraulic pressure generating means for generating a pressure and a wheel brake which is actuated by applying a hydraulic pressure from the hydraulic pressure generating means. .

[0002]

2. Description of the Related Art This type of hydraulic brake device for an electric vehicle is known, and is disclosed in, for example, Japanese Unexamined Patent Publication No. 5-161211.
It is described in JP-A-5-176406.

In the hydraulic brake device described in Japanese Patent Laid-Open No. 5-161211, an opening / closing solenoid valve and a relief valve are arranged in parallel with each other in a hydraulic pressure transmission path between a master cylinder operated by a brake pedal and a wheel brake. Installed in a relationship. This relief valve has a valve element that is opened by a pressure difference between an inlet and an outlet and closed by the force of a spring. A linear solenoid that adjusts the spring force of the relief valve is installed. When the vehicle is braked, the opening / closing solenoid valve is operated to the closed position, and the hydraulic pressure applied from the master cylinder to the wheel brakes is reduced by the relief valve by an amount corresponding to the force of the spring. The amount of pressure reduction by the relief valve can be changed by changing the force of the spring with the linear solenoid.

In the hydraulic brake device disclosed in Japanese Patent Laid-Open No. 5-176406, a hydraulic pressure path between a master cylinder operated by a brake pedal and a wheel brake is provided.
The on-off solenoid valve and the relief valve are installed in parallel relationship with each other. This relief valve has a valve body that is opened by the pressure difference between the inlet and the outlet and closed by the force of the spring.
The spring force is fixed. During vehicle braking, the electromagnetic on-off valve is operated to the closed position, and the hydraulic pressure applied from the master cylinder to the wheel brakes is reduced by a fixed amount corresponding to the force of the spring.

[0005]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
The hydraulic brake device described in Japanese Patent Publication No. 6 is small in size and inexpensive because of its simple structure. However, since the amount of pressure reduction by the relief valve is fixed, the required vehicle braking force is maintained while maintaining high regeneration efficiency. Can't get Also,
In the hydraulic brake device described in JP-A-5-161211, the amount of pressure reduction by the relief valve is variable, so the required vehicle braking force can be obtained while maintaining the regeneration efficiency at a high value. It is large and expensive because it requires a linear solenoid for changing the spring force and an electric circuit for linearly controlling its current.

In a hydraulic braking device for an electric vehicle equipped with a regenerative braking device, a small-sized and inexpensive depressurizing device, in which the amount of hydraulic pressure applied to a wheel brake from a hydraulic pressure generating device such as a master cylinder is variable, is provided. desired.

The invention of this application provides a hydraulic brake device for an electric vehicle, which is equipped with a small-sized and inexpensive pressure-reducing means in which the amount of pressure reduction of the hydraulic pressure applied to the wheel brakes from the fluid-pressure generating means is variable. With the goal.

[0008]

A hydraulic braking device for an electric vehicle according to the invention of the present application is a hydraulic braking device for an electric vehicle provided with a regenerative braking device as set forth in claim 1. A hydraulic pressure generating means for generating a hydraulic pressure corresponding to the brake operating force; a wheel brake operated by the hydraulic pressure; a hydraulic pressure transmission path for transmitting the hydraulic pressure generated by the hydraulic pressure generating means to the wheel brake; It is installed in the hydraulic pressure transmission path to reduce the hydraulic pressure transmitted from the hydraulic pressure generating means to the wheel brakes through the hydraulic pressure transmission path,
A relief valve having a valve body which is opened by a pressure difference between the hydraulic pressure generating means and the wheel brake and closed by the force of a spring, and in order to reduce the hydraulic pressure of the wheel brake when the brake operation is released. A hydraulic brake device having a brake release valve means connected in parallel to the relief valve in a hydraulic pressure transmission path, wherein the differential pressure between the wheel brake and a control hydraulic chamber causes the spring to pass through the spring. A control piston for pushing the valve body in the closing direction is installed, and the area where the differential pressure between the wheel brake and the control hydraulic pressure chamber acts on the control piston is the hydraulic pressure generating means on the valve body. Is set to be larger than the area on which the differential pressure between the wheel brake and the wheel brake acts, and a control hydraulic pressure introducing path for introducing the hydraulic pressure of the hydraulic pressure generating means into the control chamber and the control hydraulic pressure introducing path. In which the control hydraulic-pressure pressure off solenoid valve for opening and closing is installed.

In such a structure, the hydraulic pressure transmission path from the hydraulic pressure generating means to the wheel brake is closed by the relief valve when the brake operation is not performed. When the brake operation is performed, the hydraulic pressure generating means generates a hydraulic pressure corresponding to the brake operating force. Since the opening / closing solenoid valve for increasing the control hydraulic pressure is opened at the start of vehicle braking, the hydraulic pressure of the hydraulic pressure generating means is introduced into the control hydraulic pressure chamber, and the differential pressure between the hydraulic pressure generating means and the wheel brakes is increased. It acts on the valve body and the control piston of the relief valve. The force exerted on the valve body by the differential pressure and the force exerted on the control piston by the differential pressure oppose each other via a spring, and the differential pressure acting area of the control piston is larger than the differential pressure acting area of the valve body. As long as the control hydraulic pressure opening / closing solenoid valve is in the open position, the relief valve keeps closing the hydraulic pressure transmission path, and the differential pressure between the hydraulic pressure generating means and the wheel brake increases the hydraulic pressure of the hydraulic pressure generating means. As the spring force increases. When the opening / closing solenoid valve for increasing control hydraulic pressure is operated from the open position to the closed position, the increase in the differential pressure acting on the control piston stops and the increase in the spring force stops. When the differential pressure increases and the force exerted on the valve body by the differential pressure exceeds the force of the spring, the relief valve opens and hydraulic pressure is applied from the hydraulic pressure generating means to the wheel brakes. The hydraulic pressure of the hydraulic pressure generating means is reduced by a hydraulic pressure value determined by the force of the spring of the relief valve and applied to the wheel brakes.The force of the spring of the relief valve is the control fluid introduced into the control hydraulic pressure chamber. Determined by pressure. If the opening / closing solenoid valve for increasing the control fluid pressure is operated to the closed position when the fluid pressure of the fluid pressure generating means is low, the control fluid pressure in the control fluid pressure chamber will be low and the pressure reduction amount of the relief valve will be small. . If the control hydraulic pressure opening / closing solenoid valve is operated to the closed position when the hydraulic pressure of the hydraulic pressure generating means is high, the control hydraulic pressure in the control hydraulic chamber becomes a high value, and the pressure reduction amount of the relief valve is large. Becomes

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention according to the present application will be described below with reference to the drawings.

1 and 2 show a first embodiment. In FIG. 1, 11 is a traveling electric motor,
It is connected to the front left wheel 13 and the front right wheel 14 via the transmission 12. Reference numeral 15 is a rear left wheel, and 16 is a rear right wheel. Reference numeral 17 is a wheel brake for the wheel 13, 18 is a wheel brake for the wheel 14, 19 is a wheel brake for the wheel 15, and 20 is a wheel brake for the wheel 16.

The brake pedal 21 is a master cylinder 22.
The master cylinder (tandem master cylinder) 22 is connected to the brake pedal 21 and generates a hydraulic pressure corresponding to the brake operating force applied to the brake pedal 21. Master cylinder 2
The hydraulic pressure of 2 is transmitted to the wheel brakes 17 and 18 by the hydraulic pressure transmission path 23 and is transmitted to the wheel brakes 19 and 20 by the hydraulic pressure transmission path 24. Hydraulic pressure transmission path 24
A well-known proportional pressure reducing valve 25 for approximating the front-rear braking force distribution to the ideal distribution is installed in.

The master cylinder 22 is provided in the hydraulic pressure transmission path 23.
A relief valve 26 for reducing the hydraulic pressure applied to the wheel brakes 17 and 18 is installed. The valve body 27 of the relief valve 26 is closed by the force of the spring 28, and the master cylinder 22 and the wheel brakes 17, 1 are closed.
It is opened by the pressure difference between 8 and. A brake release check valve 29 is connected in parallel with the relief valve 26 to the hydraulic pressure transmission path 23 in order to reduce the hydraulic pressure of the wheel brakes 17 and 18 when the brake operation is released. Further, in order to eliminate the pressure difference between the master cylinder 22 and the wheel brakes 17 and 18 during the brake operation, a normally open differential pressure eliminating opening / closing solenoid valve 30 is provided in parallel with the relief valve 26 in the hydraulic pressure transmission path 23. It is connected.

The spring 28 of the relief valve 26 is provided between the valve body 27 and the control piston 31 in order to make the amount of pressure reduction of the relief valve 26 variable. Control piston 31
Presses the valve body 27 in the closing direction via the spring 28 by the differential pressure between the control hydraulic chamber 32 and the wheel brakes 17, 18. The differential pressure acting area of the control piston 31 is set to be slightly larger than the differential pressure acting area of the valve body 27. A control fluid pressure introducing passage 33 for introducing control fluid pressure from the master cylinder 22 to the control fluid pressure chamber 32 and a normally open control fluid pressure increasing opening / closing solenoid valve 34 for opening and closing the control fluid pressure introducing passage 33 are installed. ing. The solenoid valve 30 is closed and the solenoid valve 34
In the state in which is open, the differential pressure between the master cylinder 22 and the wheel brakes 17 and 18 acts on the valve body 27 and the control piston 31, and the differential pressure acting area of the control piston 31 is Since the control piston 31 is set to be slightly larger than the differential pressure acting area, the control piston 31 slides toward the valve body 27 in accordance with the increase in the differential pressure between the master cylinder 22 and the wheel brakes 17 and 18, and the spring. The force of 28 is increased and the valve body 27 does not open. When the solenoid valve 34 is actuated to the closed position, the control hydraulic pressure in the control hydraulic chamber 32 stops increasing and the force of the spring 28 stops increasing, so that the difference between the master cylinder 22 and the wheel brakes 17, 18 is reduced. The valve body 27 opens due to the increase in pressure. Valve body 2 of control piston 31
The sliding amount in the seven directions is limited to the amount S, and thus the maximum value of the force of the spring 28 is also limited. Solenoid valve 34
A check valve 34a is incorporated therein to allow only the flow from the control hydraulic chamber 32 to the master cylinder 22 under the condition where the electromagnetic valve 34 is in the closed position.

The master cylinder 22 is provided in the hydraulic pressure transmission path 23.
Sensor 35 for detecting the hydraulic pressure of the wheel brake 1
A pressure sensor 36 for detecting the hydraulic pressures of 7 and 18 is connected. Further, a rotation speed sensor 37 that detects the rotation speed of the traveling electric motor 11 is installed. The outputs of the pressure sensors 35 and 36 and the output of the rotation speed sensor 37 are input to the controller 38. The controller 38 includes the solenoid valves 30 and 3
4, the electric motor 11, the transmission 12, and the battery 39.

The processing contents of the controller 38 are shown in FIG. In step 101, it is determined whether or not the ignition switch IG is on, and if the determination result is N (no), the process returns to step 101. Step 10
If the judgment result in 1 is Y (yes), step 1
02, it is determined whether the flag A is 0 (meaning that the solenoid valves 30 and 34 should be set to the initial state). If the determination result is Y, the routine proceeds to step 103, where the solenoid valves After turning off 34 (open position) and turning on the solenoid valve 30 (closed position), the routine proceeds to step 104. If the determination result in step 102 is N, step 104
Proceed to.

In step 104, the master cylinder 22
It is determined whether the hydraulic pressure Pm of the wheel brake is equal to the hydraulic pressure Pw of the wheel brakes 17 and 18. If the determination result is Y (whether the brake operation is not performed or the brake operation is not performed). Is performed but the regenerative braking is not applied), the routine proceeds to step 105, where it is determined whether the rotation speed Nm of the traveling electric motor 11 is 0 (zero). If the determination result is Y (When the vehicle is stopped) The routine proceeds to step 106, the solenoid valve 30 is turned off (open position), the flag A is set to 1, and then the routine returns to step 101. As described above, when the vehicle is stopped, the regenerative brake is not applied, the solenoid valve 30 is opened, and the hydraulic pressure of the master cylinder 22 is applied to the wheel brakes 17 and 18 without being reduced. The vehicle braking force is secured only by the hydraulic brake.

When the result of the determination in step 105 is N, the routine proceeds to step 107, the state of the electric motor 11 and the transmission 12
It is determined whether the regenerative braking is prohibited or not based on the state of No., the state of the battery 39, and the like. If the determination result is Y, the process proceeds to step 106. If the determination result is N, the process proceeds to step 108 and flag A is set. Is set to 0 and the process returns to step 101.

If the result of the determination in step 104 is N, the operation proceeds to step 109, in which it is determined whether the rotational speed Nm is less than the predetermined rotational speed N1, and if the result of the determination is Y, the operation proceeds to step 110, The solenoid valve 34 is turned on (closed position), the solenoid valve 30 is turned off, the flag A is set to 1, and the process returns to step 101. Due to the characteristics of the electric motor 11 for traveling, when the rotational speed Nm is less than the predetermined rotational speed N1, the regenerative braking action cannot be expected, so the regenerative braking does not act and the vehicle braking force is secured only by the hydraulic brake. is there.

If the result of the determination in step 109 is N, the routine proceeds to step 111, where the hydraulic pressure Pm of the master cylinder 22.
And the hydraulic pressure Pw of the wheel brakes 17 and 18 are calculated, and the target value M of the regenerative braking torque is calculated based on the differential pressure ΔP, and then the process proceeds to step 112 to achieve the target value M. 11 executes regenerative braking control. Next, the routine proceeds to step 113, where the regenerative current value I is detected and the actual value M1 of the regenerative braking torque is calculated based on the regenerative current value I. Next, the routine proceeds to step 114, where it is judged if the actual value M1 is equal to the target value M, and if the judgment result is Y, the flag A is set to 0 at step 115, and then the routine returns to step 101. That is, when the regenerative braking torque has not reached the maximum value, the regenerative braking control is continuously executed.

When the result of the determination in step 114 is N, that is, when the regenerative braking torque reaches the maximum value, the routine proceeds to step 116, where the solenoid valve 34 is turned on. When the solenoid valve 34 is turned on, the control hydraulic pressure in the control hydraulic chamber 32 stops increasing and the force of the spring 28 stops increasing, so that the hydraulic pressure in the master cylinder 22 further increases and the relief valve 26 opens to open the wheel brake. The hydraulic pressure is applied to the wheels 17 and 18, and the wheels 13 and 14 are braked by both the regenerative brake and the hydraulic brake.

Next, the routine proceeds to step 117, where the differential pressure reduction correction amount ΔP1 is calculated based on the deviation (unreached amount) of the actual value M1 from the target value M, and the routine proceeds to step 118 where the differential pressure reduction correction amount ΔP1 is the first value. It is determined whether or not it is larger than the predetermined value ΔPm1, and if the determination result is N, step 11
After the flag A is set to 1 at 9, the process returns to step 101. The fact that the differential pressure reduction correction amount ΔP1 is not larger than the predetermined value ΔPm1 means that the insufficient amount of the braking force applied to the wheels 13 and 14 by the regenerative brake and the hydraulic brake is within the allowable range. The braking force is continuously applied to the engine by the regenerative brake and the hydraulic brake. When the determination result in step 118 is Y, that is, when the insufficient amount of the braking force applied to the wheels 13 and 14 by the regenerative brake and the hydraulic brake is out of the allowable range, the process proceeds to step 120 and the solenoid valve 30 is turned on. After turning off and setting the flag A to 1, the process returns to step 101. When the solenoid valve 30 is turned off, the pressure difference between the master cylinder 22 and the wheel brakes 17 and 18 is eliminated, the brake torque of the wheel brakes 17 and 18 is increased, and the required braking force of the vehicle is secured.

3 and 4 show the second embodiment. As is clear from a comparison between FIG. 1 and FIG. 3, the second embodiment has a configuration in which a normally closed control hydraulic pressure reducing opening / closing solenoid valve 40 is added to the configuration of the first embodiment. The solenoid valve 40 opens and closes a hydraulic passage 41 that allows the control hydraulic pressure in the control hydraulic chamber 32 to escape to the wheel brakes 17 and 18. Solenoid valve 3
The control hydraulic pressure in the control hydraulic chamber 32 can be reduced by operating the solenoid valve 40 in the open position while operating the valve 4 in the closed position. The processing contents of the hydraulic brake controller 39 of the second embodiment are shown in FIG. In FIG. 4, in response to the addition of the solenoid valve 40, processing contents for turning off the solenoid valve 40 (closed position) are added to step 103, and the solenoid valve 40 is turned on for a predetermined time (open position) in step 110. After that, the processing content to turn off is added, and further step 1
18 and step 120, the differential pressure reduction correction amount ΔP1
Is the correction amount upper limit value ΔPm2 (however, ΔPm1 <ΔPm2)
A step 121 for determining whether or not it is larger is inserted, and when the determination result in this step 121 is N, the routine proceeds to step 122, and after turning on the solenoid valve 40 for a predetermined time and turning it off, then to step 101. Returning to the step 121, if the determination result in the step 121 is Y, the process proceeds to the step 120. Then, in step 120, processing contents for turning on the solenoid valve 40 (open position) for a predetermined time and then turning it off are added. By turning on the solenoid valve 40 for a predetermined time while turning on the solenoid valve 34 and then turning it off, the control fluid pressure in the control fluid pressure chamber 32 is reduced only, the pressure reduction amount of the relief valve 26 is reduced, and the wheel Brake 17,18
Brake torque is increased. In the second embodiment,
When the actual regenerative brake torque value M1 is less than the target value M, the pressure reduction amount of the relief valve 26 can be reduced to increase the brake torque of the hydraulic brake. Therefore, it is necessary to maintain the regenerative efficiency at a high value. It is convenient for obtaining a good vehicle braking force.

The check valve 29 can be replaced with a proportional pressure reducing valve. The pressure reducing action starting pressure of the proportional pressure reducing valve is set to a low value such that a brake torque starts to be generated in the hydraulic brake, and the pressure reducing ratio is large.

Further, the hydraulic pressure passage 41 in FIG. 3 can be replaced with a hydraulic pressure passage provided between the control hydraulic pressure chamber 32 and the reservoir attached to the master cylinder 22. In this case, it is possible to repeatedly increase and decrease the control hydraulic pressure in the control hydraulic pressure chamber 33 many times.

[0026]

The hydraulic brake device for an electric vehicle according to the invention of this application maintains the regeneration efficiency at a high value because the amount of pressure reduction of the hydraulic pressure applied from the hydraulic pressure generation means to the wheel brakes is variable. The required vehicle braking force can be obtained. Further, the pressure reducing means can be made small and inexpensive.

[Brief description of drawings]

FIG. 1 is a diagram showing a first embodiment of the invention of this application.

FIG. 2 is a diagram showing the processing contents of a controller in FIG.

FIG. 3 is a diagram showing a second embodiment of the invention of this application.

FIG. 4 is a diagram showing processing contents of a controller in FIG.

[Explanation of symbols]

 11 ... Running electric motor 13, 14 ... Wheels 17, 18 ... Wheel brake 23 ... Hydraulic pressure transmission path 26 ... Relief valve 27 ... Valve body 28 ... Spring 29 ... -Brake release check valve 31 ... Control piston 32 ... Control fluid pressure chamber 33 ... Control fluid pressure introduction path 34 ... Control fluid pressure increasing / closing solenoid valve 34a ... Check valve 38・ ・ ・ Controller 39 ・ ・ ・ Battery 40 ・ ・ ・ Open / close solenoid valve for control fluid pressure reduction

Claims (5)

[Claims] 1. A hydraulic brake device for an electric vehicle equipped with a regenerative brake device, comprising: hydraulic pressure generating means for generating a hydraulic pressure corresponding to a brake operating force; a wheel brake operated by the hydraulic pressure; A hydraulic pressure transmission path for transmitting the hydraulic pressure generated by the pressure generation means to the wheel brakes, and the hydraulic pressure transmission path for reducing the hydraulic pressure transmitted from the hydraulic pressure generation means to the wheel brakes via the hydraulic pressure transmission path. A relief valve having a valve body that is installed in a hydraulic pressure transmission path and that is opened by a pressure difference between the hydraulic pressure generating means and the wheel brake and closed by the force of a spring; and the wheel when the brake operation is released. A hydraulic brake device having brake release valve means connected in parallel to the relief valve in the hydraulic transmission path for reducing the hydraulic pressure of the brake, wherein the wheel brake and the control hydraulic chamber A control piston for pushing the valve body in the closing direction via the spring is installed by a pressure difference between the wheel brake and the control hydraulic pressure chamber. The area to be set is set larger than the area where the differential pressure between the hydraulic pressure generating means and the wheel brake acts on the valve body, and the hydraulic pressure of the hydraulic pressure generating means is introduced into the control chamber. A hydraulic brake device for an electric vehicle, comprising: a control hydraulic pressure introducing passage; and a control hydraulic pressure increasing / closing solenoid valve for opening and closing the control hydraulic pressure introducing passage. 2. The hydraulic brake device for an electric vehicle according to claim 1, wherein the control hydraulic pressure introducing passage has the opening / closing solenoid valve for increasing the control hydraulic pressure in a closed position. A hydraulic brake device for an electric vehicle, comprising a check valve for allowing only a flow from a control hydraulic chamber to the hydraulic pressure generating means. 3. The hydraulic braking device for an electric vehicle according to claim 1, wherein a differential pressure between the hydraulic pressure generating means and the wheel brake is detected, and the regenerative braking torque is detected based on the differential pressure. The target value is calculated, the running motor is regeneratively controlled based on this target value, the regenerative current of the running motor is detected, the actual value of the regenerative braking torque is calculated based on this regenerative current, and this actual value is used as the target value. A hydraulic brake for an electric vehicle is provided with a control means for operating the control hydraulic pressure increasing / decreasing opening / closing solenoid valve from an open position to a closed position when an actual value is less than a target value. apparatus. 4. The hydraulic brake device for an electric vehicle according to claim 1, wherein a control hydraulic pressure reducing opening / closing solenoid valve for reducing the control hydraulic pressure of the control hydraulic chamber is installed. A hydraulic braking device for electric vehicles. 5. The hydraulic braking device for an electric vehicle according to claim 4, wherein a differential pressure between the hydraulic pressure generating means and the wheel brake is detected, and the regenerative braking torque is detected based on the differential pressure. The target value is calculated, the running motor is regeneratively controlled based on this target value, the regenerative current of the running motor is detected, the actual value of the regenerative braking torque is calculated based on this regenerative current, and this actual value is used as the target value. When the actual value is less than the target value, the differential pressure reduction correction amount is calculated, and based on this differential pressure reduction correction amount, the control fluid pressure increasing / closing solenoid valve and the control fluid pressure reducing / opening solenoid valve are calculated. A hydraulic brake device for an electric vehicle, comprising: a control unit that operates a valve to reduce the control hydraulic pressure to reduce the differential pressure by a differential pressure reduction correction amount.