JPH0539025A - Brake control device - Google Patents

Abstract

PURPOSE:To provide a brake operation feeling without feeling physical disorder in a brake control device for controlling braking force applied to respective wheels. CONSTITUTION:An electronic oil pressure control valve (f) and an oil pressure booster are provided between a master cylinder (b) and a wheel cylinder (d), while a damper (h) for securing a stroke in accordance with operating force for a brake operating means (a) is provided in a master cylinder pressure system.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brake control device for controlling a braking force applied to each wheel.

[0002]

2. Description of the Related Art Conventionally, as a brake control device, for example, JP-A-62-149543 and "SAE Paper 84" have been used.
The device described in Fig. 3 on page 3 of "No. 0468" is known.

In the former conventional source, a modulatable pressure device and a pressure modulator are provided between a master cylinder and a wheel cylinder, and the modulatable pressure device receives a master cylinder pressure and an external pressure to obtain a pressure of a desired multiple of the master cylinder pressure. And a pressure modulator that outputs a brake pressure corresponding to the sum of this pressure and the master cylinder pressure.

In the latter conventional source, a ball valve and a pressure reducing valve which are interlocked with each other are provided between a master cylinder and a wheel cylinder, and a constant pressure from an external hydraulic source is controlled via a three-position solenoid valve. There is disclosed a device capable of closing the ball valve and increasing / decreasing the enclosed wheel cylinder pressure by using the pressure reducing valve by making it hydraulic pressure and applying it to the pressure reducing valve.

[0005]

However, in the former brake control device, a boost control function for increasing the master cylinder pressure by having a variable pressure regulator and an external hydraulic power source are provided for the wheel when the brake is not operated. Since it is possible to apply pressure to the cylinder, it is possible to achieve a traction control function (hereinafter referred to as TCS function) that suppresses drive wheel slip by braking force when drive wheel slip occurs, but the wheel cylinder pressure is less than the master cylinder pressure. Due to the inability to control the pressure reduction, there is a problem that the anti-skid brake function (hereinafter referred to as ABS function) for preventing wheel braking lock cannot be achieved at the time of sudden braking or low μ road braking.

The latter brake control device has a TCS function by having an external hydraulic source and being able to apply pressure to the wheel cylinders when the brake is not operated, and a pressure reducing valve by closing the ball valve. Because the wheel cylinder pressure can be controlled to increase or decrease by
Although the BS function can be achieved, the control of the wheel cylinder pressure is performed by cutting off the master cylinder pressure, so that there is a problem that the boosting control function for increasing the master cylinder pressure cannot be achieved.

Therefore, the present applicant has filed Japanese Patent Application No. 2-2020.
In the application specification and drawings of No. 10, a brake control device that supports all of the boost control function, the ABS function, and the TCS function is proposed.

However, the brake control device of this prior application is
The brake pedal was depressed because the device provided with an electronic hydraulic control valve that cuts the direct communication between the master cylinder and the wheel cylinder and regulates the hydraulic pressure supplied from the external hydraulic pressure source using the master cylinder pressure as the pilot pressure. At this time, the amount of liquid discharged from the master cylinder is limited to the slight movement amount of the spool of the electronic hydraulic control valve and the initial movement amount of the wheel cylinder until the port of the brake pressure synthesizer is closed. Therefore, there is almost no pedal stroke with respect to the pedaling force applied to the brake pedal, resulting in so-called "plate depression".

The present invention has been made by paying attention to the above-mentioned problems. The direct communication between the master cylinder and the wheel cylinder is cut off, and the hydraulic pressure supplied from the external hydraulic pressure source is used as the master cylinder pressure as the pilot pressure. An object of the present invention is to obtain a comfortable brake operation feeling in a brake control device that regulates pressure to control braking force.

[0010]

In order to solve the above problems, in the brake control device of the present invention, a hydraulic control valve is provided between the master cylinder and the wheel cylinder, and the master cylinder pressure system operates the brake operating means. A damper is provided to secure a stroke according to the force.

That is, as shown in the claim correspondence diagram of FIG. 1, a master cylinder b for generating a master cylinder pressure PM in accordance with an operating force applied to a brake operating means a and a braking device c for each wheel are provided. A wheel cylinder d, an electronic hydraulic control valve f for adjusting the hydraulic pressure supplied from an external hydraulic pressure source e by using the master cylinder pressure PM as a pilot pressure to control the wheel cylinder pressure PW, and a master cylinder connected to the master cylinder b. A damper h provided in the pressure system, the volume of which changes according to the pressure level of the master cylinder pressure PM, is provided.

[0012]

When braking, the hydraulic pressure supplied from the external hydraulic pressure source e is regulated by the hydraulic pressure control valve f with the master cylinder pressure PM generated according to the operating force on the brake operating means a as the pilot pressure, and the wheel cylinder pressure PW is obtained. And applied to the wheel cylinders d provided in the braking device c of each wheel.

At this time, the volume of the damper h provided in the master cylinder pressure system connected to the master cylinder b changes according to the pressure level of the master cylinder pressure PM.
That is, the amount of liquid discharged from the master cylinder b is absorbed by the volume change of the damper h, and a sufficient brake operation stroke that does not make the brake operation means a feel uncomfortable is secured. In addition, it is possible to obtain a desired brake operation feeling by arbitrarily setting the characteristics of the damper h.

[0014]

Embodiments of the present invention will be described below with reference to the drawings.

First, the structure will be described.

FIG. 2 is an overall system diagram showing a brake control device according to an embodiment of the present invention. The embodiment device is a master for generating a master cylinder pressure PM in accordance with an operation force applied to a brake pedal 1 (corresponding to a brake operating means). Cylinder 2 and
It has a wheel cylinder 4 provided in each disc brake device 3 (corresponding to a braking device) of each wheel, and a master cylinder pressure chamber 50 to which a master cylinder pressure PM is supplied from a master cylinder pressure port 5e. An electronic hydraulic control valve 5 which uses the force of the pressure PM for the pressure increasing side of the spool 51 and the force of the proportional solenoid 52 for the pressure reducing side of the spool 51, and an accumulator pressure oil passage for the input port 5a of the electronic hydraulic control valve 5. An external hydraulic pressure source 7 connected via an oil pump 7a, a check valve 7b, and an accumulator 7c and a branch oil passage 6a of the accumulator pressure oil passage 6 are provided to open the accumulator pressure. TCS pressure P based on PS
The electromagnetic switching valve 8 that causes T to act on the pressure increasing side of the spool 51 via the TCS port 5b of the electronic hydraulic control valve 5, and the control hydraulic pressure PC that is a high wheel cylinder pressure PW due to the difference in the pressure receiving area of the step plunger 121. Hydraulic booster 12
And a linear characteristic damper 17 (corresponding to a damper), which is provided in communication with the master cylinder pressure chamber 50 of the electronic hydraulic control valve 8 and whose volume changes according to the pressure level of the master cylinder pressure PM, and the control oil pressure PC. As a pilot pressure, the pilot switching valve 18 is switched to the shutoff side when the control oil pressure PC is generated, and is switched to the side where the master cylinder pressure PM is directly applied to the wheel cylinder 4 when the control oil pressure PC is not generated.
It has and.

The electronic hydraulic control valve 5 includes a first plunger 5 between the master cylinder pressure chamber 50 and the spool 51.
3, the second plunger 54, the pedestal 55 and the third plunger 56 are arranged, and the valve case 60 and the first plunger 5 are arranged.
The first spring 57 is interposed between the valve case 6 and
A second spring 58 is interposed between 0 and the second plunger 54. The first spring 57 is set to have a higher setting force than the second spring 58. And spool 5
A third spring 59 for pushing the spool 51 rightward in the drawing is provided on the side of the proportional solenoid 52 of No. 1. Further, an output port 5c and a drain port 5d are provided as ports.

The hydraulic booster 12 is a step plunger 1
A control hydraulic chamber 122 communicating with the input port 12a is formed on the large diameter side of the wheel 21, and a wheel cylinder pressure chamber 123 communicating with the output port 12b is formed on the small diameter side of the stepped plunger 121.
Is formed, and the step plunger 121 is biased in the left direction in the drawing by the return spring 124.

The proportional solenoid 5 of the electronic hydraulic control valve 5
2 and the solenoid 81 of the electromagnetic switching valve 8 are drive-controlled by a command from the brake controller 13, and the brake controller 13 includes a longitudinal acceleration sensor 14, a wheel speed sensor 15, a master cylinder pressure sensor as sensors for obtaining input information. 16 etc. are connected.

That is, the drive control by the brake controller 13 is a boost control for increasing the master cylinder pressure PM, an ABS control for preventing wheel lock during braking, and a TCS control for suppressing drive wheel slip at the time of starting or sudden acceleration. Is performed.

The linear characteristic damper 17 is built in the electronic hydraulic control valve 5 and has a piston 171 biased by a spring 170 and a damper oil chamber 172 communicating with the master cylinder pressure chamber 50. Has been done.

The pilot switching valve 18 is provided in the middle of the oil passage that connects the master cylinder pressure oil passage 10 and the master cylinder pressure port 12c that communicates with the wheel cylinder pressure chamber 123. It should be noted that the pilot switching valve 18 does not have to have an independent structure, but the hydraulic booster 12 and the pilot switching valve 18 are different from each other like the brake pressure combiner shown in the prior art.
You may make it also have the function of.

Next, the operation will be described.

(A) At the time of normal braking First, in the electronic hydraulic control valve 5 before the brake operation, the first spring 57 has a higher setting force than the second spring 58. The second plunger 54 is pressed against.

When the brake pedal 1 is stepped on, a master cylinder pressure PM is generated in the master cylinder 2 in accordance with the brake pedal force, is supplied to the master cylinder pressure port 5e of the electronic hydraulic control valve 5, and the control oil pressure PC is also increased. In the initial stage of depression that has not occurred, it is supplied to the master cylinder pressure port 12c via the pilot switching valve 18. And the master cylinder pressure PM
When PM reaches PM1, the force acting on the first plunger 53 overcomes the spring force of the first spring 57, and the first plunger 53 moves leftward in the drawing.

Therefore, the pushing force of the second plunger 54 in the right direction disappears, and the master cylinder pressure PM and the force of the second spring 58 cause the second plunger 54 to move to the left in the drawing to push the pedestal 55, and further the spool. Push 51 to the left in the drawing. The force at that time is the spring force of the second spring 58, which is F2.
And the pressure receiving area of the second plunger 54 is A4, F2
＋ A4 ・ PM.

When a force of (F2 + A4 · PM) is applied to the spool 51, the spool 51 moves to the left in the drawing and moves to the port 5
10, the accumulator pressure PS flows from the input port 5a to the output port 5c. Since the spool 51 is a two-stage spool having a step, the output port 5c
The control oil pressure PC causes a force to move the spool 51 to the right. If the large-diameter step area is A1 and the small-diameter cross-sectional area is A2, the force at that time is (A1-A2) · PC.

The balance of the spool 51 at this time is as follows: (A1-A2) .PC = A4.PM + F2-F1 (F1; spring 5
9 spring force).

Therefore, the control oil pressure PC is proportional to the master cylinder pressure PM and is the spring force (F2-F1) added.

Next, when a current is applied to the proportional solenoid 52, a force FS proportional to the current i is applied to the solenoid plunger 61.
Occurs, the spool 51 is pushed rightward in the drawing. The balance of the spool 51 at this time is (A1−A2) · PC = A4 · PM + F2−F1−FS.

Therefore, the control oil pressure PC is controlled to increase or decrease according to the current i to the proportional solenoid 52.

As described above, when the control oil pressure PC is generated in accordance with the brake operation, the pilot switching valve 18 having the control oil pressure PC as the pilot pressure is switched to the side that shuts off the oil passage, so that the control is performed. Hydraulic pressure PC is hydraulic booster 12
And the step plunger 121 is moved to the right in the drawing. When the step plunger 121 moves to the right in the drawing, the wheel cylinder pressure chamber 123 is pressurized. Therefore, the wheel cylinder pressure PW is equal to the area ratio (A5 / A6;
A5 is a large area and A6 is a small area.

By the above operation, the wheel cylinder pressure PW
Is controlled by the following equation.

PW = {A5 (A4PM + F2-F1-FS)} / {A6 (A1-A2)} This is shown in FIG. 3, that is, when the solenoid current i is zero. , The pressure increase ratio is the largest, (a)
Shows the characteristics of. When the solenoid current i is increased, the wheel cylinder pressure PW is reduced by an amount proportional to the solenoid current i, resulting in the characteristic (b). further,
When the maximum value of the solenoid current i is maintained so that the control oil pressure PC becomes zero, the pilot switching valve 18 switches to the communication side, both ports 12c and 12b communicate, and the master cylinder pressure PM becomes the wheel cylinder pressure PW as it is. ,
It becomes the (c) characteristic of FIG.

Therefore, the wheel cylinder pressure characteristic with respect to the master cylinder pressure is set in the brake controller 13 according to the vehicle state by a function or a map, and based on the information indicating the vehicle state and the information from the master cylinder pressure sensor 16. By controlling the solenoid current i, the wheel cylinder pressure can be obtained with an arbitrary boosting characteristic according to the vehicle state. That is, a boost control function having a high degree of freedom is exerted instead of a unique boost ratio.

(B) During ABS operation When wheel locking is likely to occur during sudden braking or low μ road braking, ABS operation for preventing wheel locking by a control command from the ABS controller of the brake controller 13 to the proportional solenoid 52. Is performed.

That is, as the normal boosting characteristic, for example, if the solenoid current i is obtained so that the characteristic (b) can be obtained, the boosting up to the characteristic (a) and the characteristic up to the characteristic (c) can be achieved. Decompression is possible, the slip rate of each wheel is obtained from the vehicle speed information obtained by integrating the input signal from the longitudinal acceleration sensor 14 and the wheel speed information obtained from the wheel speed sensor 15, and the slip rate is the optimum slip. The wheel cylinder pressure PW can be increased, maintained, or reduced to fall within the range of the ratio. In addition, this ABS
During operation, the oil passage switching valve 18 connects the control oil pressure oil passage 9 and the input pressure oil passage 17 and disconnects the master cylinder pressure oil passage 10 from the input pressure oil passage 17 due to the generation of the control oil pressure PC. It has been switched.

That is, the ABS for improving vehicle stability during braking.
The function can be achieved with a sufficient increase or decrease of the wheel cylinder pressure PW.

(C) When the TCS is in operation When the drive wheel slip occurs due to the sudden accelerator pedal operation at the time of starting or sudden acceleration, the brake controller 13
The TCS operation for suppressing the drive wheel slip is performed by the control command for the proportional solenoid 52 and the ON command for the solenoid 81 from the TCS controller.

That is, when the ON command is output to the solenoid 81, the electromagnetic switching valve 8 is opened,
The accumulator pressure PS is supplied to the TCS port 5b of the electronic hydraulic control valve 5 as the TCS pressure PT.

This TCS pressure PT acts on the third plunger 56 and moves the spool 51 leftward in the drawing. The balance of the spool 51 at this time is (A1−A2) · PC = A3 · PT−F1−FS (A3; pressure receiving area of the third plunger 56).

Therefore, although the master cylinder pressure PM is not generated, the control oil pressure PC changes from the maximum pressure determined by the TCS pressure PT to the pressure obtained by reducing the force FS proportional to the solenoid current i by the solenoid current i. It can be controlled arbitrarily. The characteristic is the characteristic shown in FIG.

That is, the braking force can be applied to the drive wheels in accordance with the amount of the drive wheel slips generated, and the TCS function of effectively suppressing the drive wheel slips is exhibited.

(D) At the time of failure At the time of failure of the electronic control system related to the brake controller 13, the current i to the proportional solenoid 52 is made zero and the electromagnetic opening / closing valve 8 is closed.

Therefore, since the force acting on the spool 51 is (A1−A2) · PC = A4 · PM + F2−F1, ABS operation and TCS operation cannot be performed, but the characteristic (a) of FIG. 3 is retained. To be done.

That is, the state of maximum capacity of the brake boosting performance is secured, and the braking action having the boosting function is guaranteed.

When the hydraulic source pressure fails such that the accumulator pressure PS is not output from the external hydraulic source 7 due to a failure of the oil pump 7a or the like, the control hydraulic pressure PC is not generated by the electronic hydraulic control valve 5. When the control oil pressure PC is not generated in this way, the pilot switching valve 18 having the control oil pressure PC as the pilot pressure is switched to the communication side as shown in FIG. The wheel cylinder pressure PW is directly applied to the wheel cylinder 4 of each wheel.

Therefore, when the pressure of the hydraulic pressure source fails, the braking action is guaranteed as shown in the characteristic (c) of FIG.

(E) Pedal operation During a brake operation on the brake pedal 1 such as during normal braking, a straight line provided in communication with the master cylinder pressure chamber 50 of the master cylinder pressure system connected to the master cylinder 2. The characteristic damper 17 changes the master cylinder pressure PM.
The volume changes according to the pressure level of. That is, the amount of liquid discharged from the master cylinder 2 is added to the amount of movement of the spool 51 and the initial amount of movement of the wheel cylinder 4 (the amount of movement until the pilot switching valve 18 is closed), plus the volume of the linear characteristic damper 17. Determined by the amount of displacement due to change. Among these, the movement amount of the spool 51 and the wheel cylinder 4 is limited to a small amount, but the displacement amount of the linear characteristic damper 17 is sufficiently large, so that most of the liquid amount discharged from the master cylinder 2 is absorbed. Therefore, looking at the relationship between the pedal depression force proportional to the master cylinder pressure PM and the pedal stroke proportional to the fluid amount, a single spring 17 having a constant spring constant is used.
By using the linear characteristic damper 17 based on 0, as shown in FIG.
As shown in FIG. 5, the pedal stroke is linearly proportional to the pedal effort, and a sufficient pedal stroke without a feeling of discomfort can be secured according to the depression operation on the brake pedal 1.

As described above, in the brake control device of the embodiment, the effects listed below can be obtained.

(1) In the brake control device for arbitrarily controlling the braking force applied to each wheel regardless of whether or not the brake is operated, between the master cylinder 2 and the external hydraulic power source 7 and the wheel cylinder 4 of each wheel, respectively. Since the electronic hydraulic control valve 5, the electromagnetic switching valve 8 and the hydraulic booster 12 are provided,
It is possible to support all of the boost control function, the ABS function, and the TCS function.

(2) Since the force by the master cylinder pressure PM is used on the pressure increasing side of the spool 51 and the force by the proportional solenoid 52 is used on the pressure reducing side, the electronic hydraulic control valve 5 is used.
When the electronic control system in which the current i to the proportional solenoid 52 is set to zero and the electromagnetic opening / closing valve 8 is closed fails, the state of the maximum capacity of the brake boosting performance is secured, and the braking action having the boosting function can be guaranteed.

(3) The control oil pressure PC is set to the pilot pressure,
Since the pilot switching valve 18 is provided which is switched to the side for supplying the master cylinder pressure PM to the wheel cylinder 4 as it is when the control hydraulic pressure PC is generated (closed) when the control hydraulic pressure PC is not generated, the pressure loss of the external hydraulic power source 7 is lost. A braking action can be secured in the event of a fall.

(4) Since the master cylinder pressure system is provided with the linear characteristic damper 17 which sufficiently absorbs the amount of the liquid discharged from the master cylinder 2 when the brake pedal 1 is depressed.
It is possible to obtain a good brake operation feeling without a feeling of stepping on the board.

Next, another embodiment of the damper will be described.

FIG. 5 is a view showing a polygonal line characteristic damper 17 ', which has a first spring 173 which acts in a region where the pedal effort is below a predetermined pedal effort, and a second spring 174 which acts together with the first spring 173 above the predetermined pedal effort. A spring for biasing the piston 171 is configured.

Therefore, looking at the relationship between the pedal depression force proportional to the master cylinder pressure PM and the pedal stroke proportional to the fluid amount, the two springs 173 whose spring constants are changed.
By using the polygonal line characteristic damper 17 ′ by 174, as shown in FIG. 6, the pedal stroke has a small inclination in the small pedaling force region and a large inclination in the large pedaling force region with respect to the pedaling force.

By using this broken line characteristic damper 17 ', it is of course possible to obtain a good brake operation feeling without a feeling of stepping on the pedal, and a pedal stroke that is easy for the driver to control during a slow brake with a small pedal effort. The amount can be controlled, and the braking force can be finely adjusted.

FIG. 7 is a diagram showing a curve characteristic damper 17 ''.
A rubber elastic body 175, which has a small spring constant when the master cylinder pressure PM is low and changes so that the spring constant increases as the master cylinder pressure PM increases, is inserted in the damper oil chamber 172. ..

Therefore, looking at the relationship between the pedaling force proportional to the master cylinder pressure PM and the pedal stroke proportional to the fluid amount, the curve characteristic damper 17 '' by the rubber elastic body 175 whose spring constant is continuously changed. As shown in FIG. 8, the pedal stroke exhibits a curve characteristic in which the inclination gradually increases as the pedal stroke shifts from the small pedaling force region to the large pedaling force region, as shown in FIG.

By using the curve characteristic damper 17 ″, it is possible to obtain a good brake operation feeling without a feeling of stepping on the pedal, and of course the pedal is easy for the driver to control at the time of gentle braking with a small pedaling force. It is possible to control by the stroke amount, the braking force can be finely adjusted, and further, there is no inflection point in the stroke characteristic, and discomfort at the inflection point is also eliminated.

Thus, by setting the stroke characteristics of the damper to an arbitrary pattern, a desired pedal feeling can be obtained.

Although the embodiment has been described above with reference to the drawings, the specific configuration is not limited to this embodiment.

For example, although the linear characteristic damper, the broken line characteristic damper, and the curved characteristic damper have been shown as examples of the damper in the embodiment, dampers such as a combination of a rubber elastic body and a spring other than those shown in the embodiment are shown. It may be a damper having a structure.

In the embodiment, the proportional solenoid is used as the actuator of the electrohydraulic control valve, but a force motor, a rotary linear conversion type motor or the like may be used.

Further, a pedal depression force sensor of the brake pedal can be used instead of the master cylinder pressure sensor of the embodiment. In this case, since a motor other than the solenoid and a sensor other than the pressure sensor can be used, it is possible to meet various design needs.

The hydraulic control valve has a booster function only,
It is also possible to use only S, only TCS, or only the turning characteristic control by the yaw rate F / B.

[0068]

As described above, according to the present invention, the hydraulic control valve is provided between the master cylinder and the wheel cylinder, and the stroke corresponding to the operating force for the brake operating means is provided in the master cylinder pressure system. Since a damper for ensuring the above is provided, it is possible to obtain an effect that a brake operation feeling can be obtained without a feeling of strangeness.

[Brief description of drawings]

FIG. 1 is a claim correspondence diagram showing a brake control device of the present invention.

FIG. 2 is an overall system diagram showing a brake control device according to an embodiment of the present invention.

FIG. 3 is a diagram showing each characteristic of a wheel cylinder pressure with respect to a master cylinder pressure in the brake control device of the embodiment.

FIG. 4 is a relational characteristic diagram of pedal depression force-pedal stroke by a linear characteristic damper used in the embodiment apparatus.

FIG. 5 is a diagram showing a polygonal line characteristic damper which is another embodiment of the damper.

FIG. 6 is a relationship characteristic diagram of pedal depression force and pedal stroke by a polygonal line characteristic damper.

FIG. 7 is a diagram showing a curve characteristic damper which is another embodiment of the damper.

FIG. 8 is a relationship characteristic diagram of pedal depression force and pedal stroke by a curve characteristic damper.

[Explanation of symbols]

 a brake operating means b master cylinder c braking device d wheel cylinder e external hydraulic source f hydraulic control valve h damper

Claims (1)

[Claims] 1. A master cylinder that generates a master cylinder pressure according to an operating force applied to a brake operating means, a wheel cylinder provided in a braking device for each wheel, and an external hydraulic power source using the master cylinder pressure as a pilot pressure. A hydraulic control valve for adjusting the hydraulic pressure supplied from the master cylinder, and a damper provided in the master cylinder pressure system connected to the master cylinder and having a volume that changes according to the pressure level of the master cylinder pressure. A characteristic brake control device.