JPH05330413A - Brake fluid pressure control device - Google Patents

Abstract

PURPOSE:To provide a brake fluid pressure control device which can obtain the braking force corresponding to various road status without the need of a special additional device. CONSTITUTION:A brake fluid pressure control device comprises a master cylinder 3 for outputting the brake fluid pressure in response to a brake pedal 1, a fluid pressure source 6 for outputting the increased brake fluid pressure, a wheel cylinder 5 connected to the master cylinder 3 through a fluid path, solenoid fluid pressure control valves 2a, 2b, 2c, 2d disposed between the master cylinder 3 and the wheel cylinder 5, and a pressure sensor 7, wherein the master pressure is electrically fed-back to the solenoid fluid pressure control valves 2a, 2b, 2c, 2d to drive a solenoid.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brake fluid pressure control device, and more particularly to a brake fluid pressure applied to the rear wheel side without the need for an additional device so that it can be successfully brought under the lock limit under various road surface conditions. It can be set, anti-lock braking system (hereinafter referred to as ABS) and traction control system (hereinafter referred to as TCS).
The present invention also relates to a brake fluid pressure control device applicable to the above.

[0002]

2. Description of the Related Art Conventionally, as this type of brake fluid pressure control device, one disclosed in Japanese Patent Laid-Open No. 64-47644 is known. This uses the hydraulic pressure supplied from the hydraulic booster as the brake hydraulic pressure for the wheels directly to the master cylinder connected in tandem, and the hydraulic pressure supplied from the hydraulic booster is applied to the brake pedal. It has a structure in which a spool valve driven by a lever that is rotated by depression is controlled. Also,
ABS and TCS are structured to be performed by another control actuator.

[0003]

However, in the above-described conventional structure, for example, the brake fluid applied to the rear wheel side is set so that it is well before the lock limit under various road surface conditions, and the ABS operates. In order to reduce the change in the rotation speed of the rear wheels and to improve the directional stability while ensuring the braking ability of the front wheels, it is necessary to install a new proportioning valve that creates a hydraulic pressure difference between the front and rear wheel cylinders. In addition, the number of parts is increased accordingly, resulting in an increase in manufacturing cost.

Further, since the hydraulic pressure controlled by the spool valve forming the hydraulic booster is controlled by the position of the spool, it is difficult to generate the hydraulic pressure proportional to the depression amount of the brake pedal.

Further, the wheel cylinder pressure characteristic (power boost ratio) resulting from the amount of depression of the brake pedal is not only constant in the amount of rising and the inclination, but an ON-OFF control solenoid valve is used for ABS control. Therefore, there is a problem that the fluctuation of the hydraulic pressure is large and the surge pressure is generated to generate sound and vibration.

The present invention has been proposed in order to solve the problems of the prior art, and provides a braking force corresponding to various road surface conditions without requiring a special additional device and has a structure. It is an object of the present invention to provide a brake fluid pressure control device that simplifies the above and reduces the amount of depression of the brake.

[0007]

In order to achieve the above object, the present invention provides a master cylinder that outputs a brake fluid pressure in response to a brake pedal, a hydraulic pressure source that outputs a boosted brake fluid pressure, and A wheel cylinder connected to a master cylinder via a fluid passage, an electromagnetic hydraulic control valve having a spool and a solenoid provided between the master cylinder and the wheel cylinder and slidable in a housing, and the master cylinder. And a pressure sensor provided between the wheel cylinder and sensing the master pressure,
In addition, the master pressure is electrically fed back to the electromagnetic pressure control valve to drive the solenoid.

[0008]

The present invention provides the pressure sensor for sensing the master pressure between the master cylinder and the wheel cylinder,
Since the master pressure is electrically fed back to the electromagnetic pressure control valve to drive the solenoid, the braking force corresponding to various road surface conditions can be obtained without the need for a special device such as a proportioning valve. As a result, the stroke of the spool of the electromagnetic hydraulic pressure control valve can be shortened, and as a result, the depression amount of the brake pedal interlocking with the master cylinder can be shortened, and the wheel cylinder pressure characteristic resulting from the depression amount of the brake pedal ( Boost ratio) can be made variable.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A brake fluid pressure control device according to the present invention will be described below with reference to the embodiments shown in the drawings.

FIG. 1 is a schematic configuration diagram of a brake fluid pressure control device according to the present invention, and FIG. 2 is a piping system diagram showing a first embodiment relating to a rear wheel portion.

The brake fluid pressure control device according to the present invention is
A master cylinder 3 that outputs a braking fluid pressure of the brake fluid in response to depression of the brake pedal 1 and a wheel cylinder 5 that is connected to the master cylinder 3 via a fluid passage are provided. Between the master cylinder 3 and the wheel cylinder 5, the electromagnetic hydraulic pressure control valves 2a, 2b, 2c and 2d constituting the brake hydraulic pressure control device 2 are provided for each wheel in this embodiment to form a booster section. In addition, the master cylinder 3 is connected to a reservoir 4 that stores brake fluid, and the electromagnetic hydraulic pressure control valves 2a, 2b, 2c, and 2d are connected to a hydraulic pressure source 6 that outputs a boosted brake hydraulic pressure. Also, the master cylinder 3 and the wheel cylinder 5
In the present embodiment, a pressure sensor 7 for sensing at least one system master pressure is provided between the and the system.

The hydraulic pressure source 6 comprises a hydraulic pump 61 driven by an electric motor (not shown), the input side of which is connected to the reservoir 4 via a liquid path, and the output side of which is connected to an accumulator 62. Via the accumulator 62, the boosted brake hydraulic pressure is supplied to the electromagnetic hydraulic pressure control valves 2a, 2b, 2c and 2d. Reference numeral 63 is a relief valve, which is disposed between a liquid passage connecting the reservoir 4 and an annular liquid passage 26b described later, and is provided with a hydraulic pressure source 6
When the hydraulic pressure on the side becomes higher than a predetermined pressure, it has a function of returning it to the reservoir 4 side. Reference numeral 8 denotes a TCS switching valve, which is arranged between the reservoir 4 and an annular liquid passage 26c described later, and supplies the hydraulic pressure from the hydraulic pressure source 6 to the brake hydraulic pressure control device 2 during the TCS control. It can be switched. Therefore, when wheel spin occurs, the control circuit (not shown) energizes the drive means (for example, an electromagnetic valve) of the TCS switching valve 8 to transfer the hydraulic pressure from the hydraulic pressure source 6 to the electromagnetic hydraulic pressure control valve 2c on the drive wheel side. It is supplied to the TCS pressure chamber 29 of 2d and acts so as to move the spool 21 to the right in the figure.

Electromagnetic hydraulic control valves 2a, 2b, 2c and 2
In the present embodiment, d is a spool valve and has a large diameter portion 21.
The spool 21 having a and a small diameter portion 21b is fitted in the housing so as to be liquid-tight and slidable in the direction of the arrow, and also has a master cylinder pressure chamber 22 communicating with the master cylinder 3 and a back cylinder communicating with the reservoir 4. Return springs 24a, 24 respectively provided in the pressure chamber 23 and
It is held in the neutral position by b. A small diameter portion 21c is formed in the step portion between the large diameter portion 21a and the small diameter portion 21b of the spool 21, and a pressure feedback chamber (wheel cylinder pressure chamber) is formed between the large diameter portion and the small diameter portion of the housing. 25
Is formed. Since the pressure feedback chamber 25 communicates with the wheel cylinder 5 via the liquid passage, the hydraulic pressure output from the pressure feedback chamber 25 becomes the wheel cylinder pressure. Further, annular liquid passages 26a and 26b are respectively provided in the large diameter portion and the small diameter portion of the housing, and the annular liquid passage 26a provided in the large diameter portion communicates with the reservoir 4 and the annular liquid passages provided in the small diameter portion. The passage 26b is the hydraulic pressure source 6
Communicate with. The pressure feedback chamber 25 has a structure that opens (communicates) with both of the annular liquid paths 26a and 26b due to the sliding of the spool 21.

Electromagnetic hydraulic control valves 2a, 2b, 2c and 2
A solenoid 27 is provided on the back pressure chamber 23 side of d.
When the S operation is performed, the spool 21 is pressed from the right side in the drawing, and the spool 21 is slid to the left side in the drawing so that the pressure feedback chamber 25 and the annular liquid passage 26a communicate with each other. A piston 28 is provided on the pressure receiving surface of the master cylinder pressure chamber 22 of the spool 21 and a TCS pressure chamber 29 is formed between the piston 21 and the large diameter portion of the spool 21 to form a TCS controller. An annular liquid passage 26c for TCS is provided in the housing so as to communicate with the TCS pressure chamber 29,
The annular fluid passage 26c communicates with the fluid pressure source 6 via the TCS switching valve 8. Reference numeral 28a is a seal provided on the sliding surface of the piston 28 with respect to the housing, so that the hydraulic pressure supplied from the master cylinder 3 to the master cylinder pressure chamber 22 does not leak to other pressure chambers. In particular, in the pressure feedback type hydraulic control device as in the present embodiment, in which the spool 21 has a stepped shape, it is general that high precision is required for the clearance between the spool 21 and the housing. As a result, it is not necessary to consider the clearance between the spool 21 and the housing, the dimensional accuracy in the coaxiality, and the like.

An accumulator 9 is provided in the fluid passage that connects the master cylinder 3 and the master cylinder pressure chamber 22, and the stroke of the spool 21 can be adjusted by sucking and discharging the working fluid pressure.

FIG. 3 shows a second embodiment of the electromagnetic hydraulic pressure control valves 2a, 2b, 2c and 2d constituting the brake hydraulic pressure control device 2 according to the present invention.
When 1 is held in the neutral position by the return springs 24a, 24b, a space 26a 'having a T-shaped cross section, which opens to the annular liquid passage 26a communicating with the reservoir 4, is formed in the large diameter portion 21a of the spool 21. is there. Also,
FIG. 4 shows a third embodiment, which differs from the first embodiment in that it has a space 26a 'having a T-shaped cross section as in the second embodiment. 2) The annular liquid passages 26a and 26b are both provided in the small diameter portion 21b of the spool 21. 2) The space defined by the stepped portion of the spool 21 and the stepped portion of the housing serves as the pressure feedback chamber 25a. The space provided between the annular liquid passages 26a and 26b in the small-diameter portion 21c constitutes a wheel cylinder pressure chamber 25b. 3) Both spaces 25a and 25b are in communication with the wheel cylinder 5. , And 3 points. However, since the operation is the same as that of the first embodiment, the description thereof will be omitted in the following description of the first embodiment.

The operation procedure of the above embodiment will be described below with reference to FIG.

That is, when the brake is normally operated, by depressing the brake pedal 1, the master cylinder 3
More predetermined brake fluid pressure is generated. This hydraulic pressure is introduced into the master cylinder pressure chamber 22 of the electromagnetic hydraulic pressure control valves 2a, 2b, 2c and 2d via the hydraulic passage, and the introduced hydraulic pressure causes the spool 21 to slide in the direction of the arrow on the right side in the figure. Move.
By this sliding, the normally closed annular liquid passage 26b communicates with the pressure feedback chamber 25. Since the brake fluid is accumulated in the accumulator 62 of the fluid pressure source 6 by the fluid pressure pump 61, the accumulator 6 is provided by the communication between the annular fluid passage 26b and the pressure feedback chamber 25.
The pressure-increasing brake fluid pressure accumulated in 2 flows into the pressure feedback chamber 25, and the pressure in the pressure feedback chamber 25 rises.

As described above, the spool 21 has the large diameter portion 2
1a and a small diameter portion 21b are formed, and a pressure feedback chamber 25 is provided facing the stepped portion of the housing. Therefore, if the area of the cross section of the large diameter portion 21a orthogonal to the axial direction of the spool 21 is A ₁ and the area of the cross section of the small diameter portion 21b is A ₂ , then the hydraulic pressure introduced into the master cylinder pressure chamber 22 is overcome. The force of pushing back the spool 21 to the left side in the figure by the hydraulic pressure of the pressure feedback chamber 25 is the force P of the difference between the two areas (A ₁ -A ₂ ).
(A ₁ −A ₂ ). As a result, the control pressure (wheel cylinder pressure) output from the pressure feedback chamber 25 to the wheel cylinder 5 is determined by the balance of the forces on the pressure receiving surfaces of the master cylinder pressure chamber 22 of the spool 21 and the pressure feedback chamber 25. ,
The control pressure of the wheel cylinder 5 will be a pressure proportional to the master cylinder pressure.

Here, as shown in FIG. 5, the solenoid 2
When 7 is energized to generate a certain suction force, the rising position of the master pressure (depressing force of the brake pedal 1) -wheel cylinder pressure characteristic generated from the master cylinder 3 shifts to the right side in the figure and changes. As is clear from FIG. 6, when the suction force of the solenoid 27 generated in proportion to the increase of the master pressure generated from the master cylinder 3 is generated, the suction force of the solenoid 27 reduces the wheel cylinder pressure, and the wheel cylinder pressure is reduced. It is shown that the slope of the characteristic changes (note that the area A ₁ ,
Similar results can be obtained by changing the relationship of A ₂ . ).
The present invention utilizes this principle, and in order to improve the directional stability while reducing the rotational speed change of the rear wheels and securing the braking ability with the front wheels, the hydraulic pressure difference between the front and rear wheel cylinders is applied by this principle. It is born. Therefore, as shown in FIG. 7, when a predetermined pressure is sensed by the pressure sensor 7 while the master pressure is increasing (for example, P ₁ or P ₂ ), the master pressure controlled by the controller 10 becomes Feedback is given to the solenoid 27 of the electromagnetic hydraulic pressure control valves 2c and 2d of the rear wheels, and the solenoid 27
To generate suction force. At this point, the inclination of FIG. 7 changes,
The break points are P ₁ and P ₂ , and if the position and inclination are variably controlled by the control device 10, it becomes possible to obtain a braking force corresponding to various road surface conditions.

The above is the case where the pressure is increased during normal brake operation, but when the pressure is maintained, the brake pedal 1 is used.
It is sufficient to hold the input of, the master cylinder pressure is also held by this, and the spool 21 stops in a balanced state,
Wheel cylinder pressure is also retained.

On the other hand, when the wheels are about to lock in the brake operating state, the ABS control is activated and the solenoid 27 of the electromagnetic hydraulic pressure control valve is excited. This allows spool 2
1 slides leftward in the figure against the spring force of the return spring 24a, and the annular liquid passage 26a and the pressure feedback chamber 2
It communicates with 5. As a result, the wheel cylinder pressure is released to the reservoir 4, and the brake fluid pressure in the wheel cylinder 5 acts in the direction of decreasing (reducing pressure). If the excitation of the solenoid 27 is maintained, the ABS operation is maintained as it is, and if the solenoid 27 is demagnetized, the spool 21 slides to the right in the figure and operates in the pressure increasing direction.

Also, when the vehicle starts or suddenly accelerates,
When the occurrence of wheel spin is detected, TCS control is performed. That is, in this case, first, the TCS switching valve 8
Of the electromagnetic fluid pressure control valve to shut off the TCS annular fluid passage 26c, and the hydraulic pressure from the accumulator 62 and the pump 61 is passed through the annular fluid passage 2
Supply to 6c. As a result, the spool 21 slides to the right in the drawing, the pressure feedback chamber 25 and the annular fluid passage 26b are communicated with each other, and the fluid pressure from the fluid pressure source 6 is transferred to the wheel cylinder 5.
The brake fluid pressure is controlled by increasing the pressure. In order to reduce the pressure of the wheel cylinder 5, the hydraulic pressure is released to the reservoir 4 via the annular hydraulic passage 26c by exciting the solenoid 27 of the electromagnetic hydraulic pressure control valve, as described above.

[0024]

As described above, according to the brake fluid pressure control device of the present invention, the pressure sensor 7 is provided in the fluid path between the master cylinder 3 and the wheel cylinder 5, and the master pressure is controlled by the electromagnetic fluid. Since the solenoid 27 of the pressure control valve is fed back to drive the solenoid 27, the electromagnetic hydraulic pressure control valves 2a, 2b, 2c and 2d can have the function of the proportioning valve without adding any additional device. Therefore, it becomes possible to obtain the braking force corresponding to various road surface conditions.

Further, the wheel cylinder pressure characteristic (power boost ratio) caused by the depression amount of the brake pedal 1 can be made variable, and the brake fluid pressure control corresponding to external factors such as the road surface and the vehicle condition can be performed. It will be possible.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a brake fluid pressure control device according to the present invention.

FIG. 2 is a piping system diagram showing a first embodiment of the present invention relating to a rear wheel portion.

FIG. 3 is a schematic configuration diagram showing a second embodiment of the electromagnetic hydraulic pressure control valve constituting the present invention.

FIG. 4 is a schematic configuration diagram showing a third embodiment of the electromagnetic hydraulic pressure control valve that constitutes the present invention.

FIG. 5 is a graph showing control characteristics of a master cylinder pressure and a wheel cylinder pressure by a solenoid according to the present invention.

FIG. 6 is a graph showing how the suction force of a solenoid affects the master cylinder pressure and the wheel cylinder pressure in the present invention.

FIG. 7 is a graph showing the results of the attraction force of the solenoid shown with respect to the master cylinder pressure and the wheel cylinder pressure in the present invention.

[Description of Reference Signs] 1 brake pedal 2a, 2b, 2c, 2d electromagnetic hydraulic pressure control valve 21 spool 22 master cylinder pressure chamber 24a, 24b return spring 25 pressure feedback chamber 26a, 26b, 26c annular fluid passage 27 solenoid 29 TCS pressure chamber 3 Master Cylinder 4 Reservoir 5 Wheel Cylinder 6 Hydraulic Pressure Source 7 Pressure Sensor 8 TCS Switching Valve

Claims (1)

[Claims] 1. A master cylinder that outputs a brake fluid pressure in response to a brake pedal, a hydraulic pressure source that outputs a boosted brake fluid pressure, a wheel cylinder that is connected to the master cylinder via a fluid passage, An electro-hydraulic pressure control valve provided between the master cylinder and the wheel cylinder and having a spool and a solenoid slidable in the housing, and a master pressure provided between the master cylinder and the wheel cylinder to sense the master pressure. A brake fluid pressure control device comprising: a pressure sensor, wherein the master pressure is electrically fed back to the electromagnetic pressure control valve to drive the solenoid.