JPH02267062A - Control device for braking hydraulic pressure for vehicle - Google Patents

Abstract

PURPOSE:To secure the incipient performance of a device with no accumulator by providing a relief valve for an oil flow way between the delivery port of a hydraulic pump and an intake valve, thereby releasing pressure to a reservoir when braking hydraulic pressure exceeds specified one. CONSTITUTION:A relief valve 22 is provided for an oil flow way 21 between the delivery port of a hydraulic pump 23 and the air intake valve chamber 18 of a master cylinder. When hydraulic pressure in the oil flow way 21 exceeds relief pressure by a spring 22f, the relief valve 22 moves a piston 22a to the right, letting a ball valve 22c come in contact with a rod 22d so as to let it be separated from its valve seat, and lets braking pressure be released to a reservoir 11. In addition, when both of the piston 22a and a piston 22h are furthermore moved to the right with an abnormal increase in braking hydraulic pressure, the actuator 70d of a switch 70 is raised up by the recessed section 22i so as to be turned off so that the hydraulic pump 23 driven by a motor 71 is suspended. By this constitution, the incipient performance of a device can be secured with no accumulator.

Description

[Detailed Description of the Invention] (Field of Industrial Application) The present invention is used for anti-lock control to prevent wheel locking during vehicle braking or traction control to prevent drive wheels from slipping when a vehicle starts or accelerates. The present invention relates to a brake fluid pressure control device.

(Prior art) An anti-lock control device that prevents wheels from locking during vehicle braking to ensure vehicle steering performance, running stability, and shorten braking distance uses wheel speeds obtained from wheel acceleration sensors. The brake fluid pressure control mode (pressurization mode, pressure reduction mode, and holding mode) is determined based on the electric signal, and the hold valve (pressurization/holding valve) and decay valve (pressure reduction A microcomputer controls the brake fluid pressure by opening and closing the brake valve (valve) to increase, maintain, or reduce the brake fluid pressure.

Incidentally, a brake hydraulic pressure control device is known in which a hydraulic pressure control section (modulator) for performing anti-lock control as described above is provided integrally with a master cylinder. In such a device, for example, as disclosed in Japanese Patent Application Laid-Open No. 57-104449, a master cylinder is configured in tandem with a primary piston and a secondary piston arranged in series with each other, and these two pistons are connected in tandem. The pistons control the hydraulic pressure of two systems of brake equipment, and the hydraulic passages connecting the two hydraulic pressure chambers whose hydraulic pressures are respectively controlled by the two pistons and the wheel cylinders are normally open. It has a structure in which a mold hold valve is provided and a normally closed decay valve is provided in the liquid passage connecting the wheel cylinder and the reservoir.

In this configuration, when the brake pedal is depressed, the hydraulic pressure in the master cylinder's hydraulic chamber is transmitted to the wheel cylinder through the hold valve, and the hydraulic pressure in the wheel cylinder increases to apply braking force to the wheels. It has become. When anti-lock control is started, the hold valve closes to maintain the brake fluid pressure, and the decay valve opens while the Bold valve is closed, allowing the brake fluid in the wheel cylinder to flow into the reservoir through the decay valve. The hydraulic pressure inside the wheel cylinder is reduced to weaken the braking force. Furthermore, when pressurizing in anti-lock control, the hold valve is opened and the piston is actuated by high-pressure brake fluid supplied from a hydraulic pressure source such as an accumulator, increasing the hydraulic pressure in the wheel cylinder. ing.

However, during anti-lock control, if a failure occurs in the hydraulic pressure source system such as a hydraulic pump, the braking force will be insufficient, and the brake pedal must be further depressed to compensate for this. There was a problem in that it was not possible to secure enough pedal clearance.

Therefore, the present applicant proposed a brake fluid pressure control device that solved the above-mentioned problems in Japanese Patent Application No. 62279038. That is, a liquid passage is provided that connects the hydraulic pressure chamber of the master cylinder and the accumulator, and a normally closed supply valve that is opened only during anti-lock control is provided in the middle of this liquid passage. An intake valve that normally closes the opening with its tip protruding into the hydraulic pressure chamber and blocks the liquid passage is provided at the opening leading to the pressure chamber, while the piston of the master cylinder is provided with an intake valve that closes the opening and blocks the liquid passage. A valve operating member is provided that moves integrally with the piston and engages with the tip of the intake valve to open the intake valve when the stroke of the piston reaches a predetermined value.

According to such a brake fluid pressure control device, the valve operating member opens the intake valve as the piston of the master cylinder moves, so during antilock control or traction control when the supply valve is open,
High-pressure brake fluid is supplied from the accumulator into the hydraulic chamber of the master cylinder, which pushes the piston back and maintains the set position, thereby providing sufficient brake pedal travel in the event of a failure in the hydraulic power system. The necessary braking force is obtained by supplying hydraulic pressure proportional to the force applied to the brake pedal to the wheel cylinder.

However, such a brake fluid pressure control device requires a large capacity accumulator and also requires a fail-safe pressure switch to monitor the fluid pressure, resulting in an increase in size, weight, and price. That was the problem.

(Objective of the Invention) Therefore, an object of the present invention is to provide a small, lightweight, and inexpensive brake fluid pressure control device of this type that can exhibit initial performance without providing an accumulator.

(Structure of the Invention) In the present invention, a relief valve is provided in the liquid passage connecting the discharge port of the hydraulic pump and the intake valve. This relief valve includes a piston that receives the hydraulic pressure in the liquid passage and the hydraulic pressure in the master cylinder chamber from opposite directions, and a valve body that is provided in the piston and moves together with the piston, and brakes the liquid passage. When the hydraulic pressure rises above a predetermined value, the valve body is opened by the movement of the piston, and the brake fluid in the fluid passage is released to a reservoir. Furthermore, the present invention includes a switch that stops the operation of the motor that drives the hydraulic pump in response to the movement of the piston to a predetermined position.

(Example) Hereinafter, examples of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows the overall configuration of an embodiment of the brake fluid pressure control device according to the present invention for a front wheel drive vehicle having a cross-piping type (X-piping) type two-system brake device. A hydraulic chamber 5. is provided with a primary piston 3 and a secondary piston 4 within the housing 2, the hydraulic pressures of which are controlled by the pistons 3.4, respectively.
6 is formed.

The hydraulic pressure chamber 5 whose hydraulic pressure is controlled by the primary screws 1 to 3 has a bold valve HV consisting of a normally open electromagnetic valve.
A cut valve C is connected to the wheel cylinder 8 of the right front wheel FR through a liquid passage 7 provided with I in the middle, and further comprises a normally open electromagnetic valve that is closed only during traction control.
It is connected to the wheel cylinder 9 of the left rear wheel RL via V1.

These wheel cylinders 8.9 are connected to a reservoir 11 via a liquid passage 10 in which a decay valve DVI, which is a normally closed electromagnetic valve, is provided in the middle.

Similarly, the hydraulic pressure chamber 6, whose hydraulic pressure is controlled by the secondary piston 4, is connected to the left front wheel FL through a hydraulic passage 12 in which a hold valve HV2, which is a normally open electromagnetic valve, is provided in the middle.
It is further connected to the wheel cylinder 14 of the right rear wheel RR via a cut valve CV2, which is a normally open electromagnetic valve that is closed only during traction control. These wheel cylinders 13.
14 is connected to the reservoir 11 via a liquid passage 15 in which a decay valve DV2, which is a normally closed electromagnetic valve, is provided in the middle.

On the other hand, in the housing 2 of the master cylinder 1, valve chambers 18.19 are formed, each having an opening 16.17 communicating with the hydraulic pressure chamber 5.6.
are connected to each other via a liquid passage 20 formed in the housing 2, and the valve chamber 19 is connected to a discharge port of a hydraulic pump 23 via a liquid passage 21. Connected to Zaha 11. Valve chamber 18.
Inside 19 is an intake valve 31.3 that also serves as a check valve.
A valve mechanism 26,27 as described below is provided, each comprising a valve mechanism 26,27. The hydraulic pump 23 is operated at least during anti-lock control or traction control.

Cylindrical intake sleeves 33.34 for operating the intake valves 31.32, respectively, are fixed to the primary piston 3 and the secondary piston 4, facing into the hydraulic pressure chamber 5.6. The primary piston 3 and the secondary piston 4 each contain a center valve 35.36 which is movable in the axial direction of the master cylinder 1 relative to the piston 3.4, and the brake pedal 37 is not depressed and therefore A butschrodt 38 connected to this brake pedal 37 via a booster 30 is connected to the primary piston 3.
In the state shown in FIG. 1 where 5. is not pressed, the hydraulic chamber 5.
Center valve 35.36 with 6 in open position, piston 3
．． 4, an annular chamber 41.42 formed around the piston 3.4, and a liquid passage 43.4, respectively.
44, respectively, and communicate with the reservoir 11.

When the brake pedal 37 is depressed, the bushing rod 38 is actuated and the primary piston 3 moves to the left in FIG. Hydraulically shut off. Therefore, the hydraulic pressure in the hydraulic chamber 5 increases, and the brake fluid in the hydraulic chamber 5 is supplied to the wheel cylinders 8.9 through the open hold valve HVI, and the wheels FR and RL is braked. and hydraulic chamber 5
The secondary piston 4 is actuated and the center valve 3G is moved to the closed position due to the increase in the hydraulic pressure inside, thereby hydraulically shutting off the hydraulic chamber 6 and the reservoir 11. Therefore, the hydraulic pressure in the hydraulic chamber 6 also increases, and the brake fluid in the hydraulic chamber 6 is supplied to the wheel cylinders 13, 14 through the open hold valve HV2, and the brake fluid in the hydraulic chamber 6 is supplied to the wheel cylinders 13, 14 of the other brake system. RR is braked.

The positional relationship and operation between each member are determined by a stop bolt 45.4 with a center valve 35.36 at one end.
6, stop bushings 47.48 that respectively engage heads 45a and 46a at the other end of these stop port 45.46, and compressed between stop bushings 47.48 and intake sleeves 33.34, respectively. This is accomplished by springs 49, 50 and 51, 52 which bias the center valves 35, 36, respectively, into the closed position.

On the other hand, in an annular chamber 41 formed between the housing 2 and the primary piston 3 of the master cylinder 1, a cylindrical auxiliary piston 53 is coaxially slidable with respect to both the housing 2 and the primary piston 3. established,
A protruding portion 53a at the left end of the auxiliary piston 53 in parentheses is in contact with the primary piston 3. The auxiliary piston 53 is provided with an annular pressure-receiving stepped portion 53b facing right in FIG.
4 is formed. 55 closes the auxiliary hydraulic pressure chamber 54;
It is also a plug member that restricts the movement of the auxiliary piston 53 to the right. The auxiliary hydraulic pressure chamber 54 is connected to the valve chamber 18 in the housing 2 via a liquid passage 56 in which a first traction valve TCV 1, which is a normally closed electromagnetic valve that is opened only during traction control, is provided in the middle. As a result, only during traction control, pressurized brake fluid is supplied from the hydraulic pump 23 to the auxiliary hydraulic pressure chamber 54 through the liquid passage 20 that communicates between the liquid passage 21 and the valve chambers 18 and 19. It looks like this. Further, the auxiliary hydraulic pressure chamber 54 is connected to the reservoir 11 via a liquid passage 57 in which a second traction valve TCV2, which is a normally open electromagnetic valve, is closed only during traction control.

In this way, the normally closed first traction valve TCV 1 that is opened only during traction control is provided in the liquid passage 56 connected to the auxiliary hydraulic pressure chamber 54, and this liquid passage 56 is connected to the hydraulic pump. A normally open second traction valve TCV2 is led out from the middle of the liquid passage 21.20 connecting the discharge 0 and the hydraulic pressure chamber 5.6, and further has an auxiliary hydraulic pressure chamber 54 closed only during traction control. Since the auxiliary hydraulic pressure chamber 54 is connected to the reservoir 11 through a liquid passage 57 provided with a hydraulic pressure, no hydraulic pressure remains in the auxiliary hydraulic pressure chamber 54 except during traction control.

A relief valve 22 is disposed in a liquid passage 21 that connects the hydraulic pump 23 and the valve chamber 19.

As shown in FIG. 7, the relief valve 22 includes a piston 22a incorporating a valve spring 22b and a ball valve 22C, and a relief spring 22f that urges the piston 22a against the discharge hydraulic pressure of the hydraulic pump 23. A hull plot 22d protrudes into the piston 22a to open the pole valve 22c, and a piston 22h that is connected to the end of the piston 22a (the right end in FIG. 7) and moves integrally with the piston 22a. , piston 22
The relief spring 22f is compressed between a spring seat 22e attached to the piston 22a and a case 22m, and a spring 22j for integrally moving the piston 22h.
Further, the valve rod 22d is connected to a groove 22 formed in the piston 22a so as not to hinder the movement of the piston 22a.
g, and is adapted to come into contact with and be received by a part of the case 22m when engaged with the ball valve 22C. The spring 22j is compressed between an opening at the rear end (right end in FIG. 7) of the piston 22h and a part of the case 22m. A piston chamber 22k formed by a part of the case 22m and the back of the piston 22h is provided at the rear end of the relief valve 22 (the right end in FIG. 7). The hydraulic pressure in the hydraulic pressure chamber 6 of the master cylinder is applied through the opening 22n.

A switch 70 made of a micro-sinch is provided in a part of the case 22m of the relief valve 22 (upper right corner in FIG. 7). This switch 70 has two fixed contacts 70
a, 70b, and a movable contact 70c, the movable contact 70
C is connected to a power source (not shown). Further, one fixed contact 70a is connected to a motor 71 that drives the hydraulic pump 23, and the other fixed contact 70b is not connected. The movable contact 70c of this switch 70 is
When the actuator 70d is pressed by the outer peripheral surface (upper part in FIG. 7) of the piston 22h of the relief valve 22, it is switched to the fixed contact 70b side as shown in FIG. 7, and the power supply to the motor 71 is cut off. When the actuator 7 (1, d falls into the four parts 22i formed on the outer peripheral surface of the piston 22h), the movable contact 70c of the switch 70 is switched to the fixed contact 70a side, and the hydraulic pump 23 is switched to the fixed contact 70a side. It is now working.

With such a configuration, the relief valve 22 is connected to the liquid passage 2.
When the brake fluid pressure of No. 1 increases, the piston 22a moves to the right in FIG.
When it comes into contact with the ball hull 22c, the hull plot 22
d, the brake fluid in the fluid passage 21 is relieved to the reservoir 11, and the fluid passage 2
This prevents abnormally high pressure from occurring within 1. When the liquid pressure in the liquid passage 21 decreases, both the piston 22a and the piston 22h integrally move to the left in FIG. , piston 22h
The hydraulic pump 23 is activated again.

In addition, in this relief valve 22, the piston 22a is biased toward the left in FIG. As it moves, the volume of the liquid chamber 221 inside the case 22m changes, which also acts to relieve the impact pressure when the hydraulic pump 23 discharges.

Furthermore, in this relief valve 22, the direction in which the ball valve 22c is seated with respect to the valve seat is the same as the direction in which the brake fluid escapes when the valve is opened.
2c is inserted into the valve seat by both hydraulic pressure and valve spring 22b, and the sealing performance of this relief valve 22 is extremely good.

In addition, in the non-braking state of this embodiment, the liquid passage 21 and the valve chambers 18 and 19 in which the relief valve 22 is provided are
Brake fluid, on which a hydraulic pressure equal to the load of the relief spring 22f acts, is always supplied to the fluid passage 20 that communicates between The intake valves 31 and 32 to which the pressure has been applied move upward as shown in FIG.
(not shown) project into the hydraulic chambers 5, 6, respectively. The set load of the relief spring 22f is set so that the brake fluid pressure when the pawl valve 22C comes into contact with the hull plot 22d and is relieved is higher than the maximum fluid pressure generated in the fluid pressure chamber 5.6. has been done.

FIG. 2 is an enlarged sectional view showing the structure of the valve mechanism 26 assuming that no hydraulic pressure is acting on the liquid passage 20. A piston chamber 61 is formed coaxially with the opening 16 of the valve chamber 18 to the hydraulic pressure chamber 5 . Inside this piston chamber 61, a piston 63 as a valve holding member equipped with a center hole 62 penetrating in the axial direction is slidable in a direction perpendicular to the inner peripheral surface 5a of the hydraulic pressure chamber 5 and has an opening. It is provided with a section 16 and a centering section. piston 63
A conical valve seat surface 63a is formed at the end of the center hole 62 (the end opposite to the opening 16).

The intake valve 31 is a rod-shaped poppet valve that is slidably provided through the opening 16 of the housing 2 and the center hole 62 of the piston 63. It is configured to appear against. The intake valve 31 is connected to the piston 63.
The hemispherical valve portion 31b is seated on the valve seat surface 63a.

Further, as shown in the cross-sectional views of FIGS. 3 and 4, the tip portion 31a and part of the shaft portion of the intake valve 31 are
The intake valve 31 has a substantially rectangular cross-sectional shape, and its four corners are slidably in contact with the inner circumferential surface of the opening 16 of the housing 2 and the inner circumferential surface of the center hole 62 of the piston 63 as support parts. This prevents twisting when the intake valve 33 is pushed down by the intake sleeve 33, thereby smoothing its operation, and forms a liquid passage 64 around the outer peripheral surface of the intake valve 31.

A spring holder 65 is integrally connected to the piston 63, and a check spring 66 is compressed between the spring holder 65 and the intake valve 31 to connect the valve portion 31b of the intake valve 31 to the piston 6.
It is seated on the valve seat surface 63a of No. 3 with a predetermined check pressure. Furthermore, the piston 63 is attached to the spring holder 6
5 and the wall surface of the valve chamber 18, the center spring 67 is biased in a direction away from the opening 16 side. The spring biasing force of the center spring 67 is made larger than that of the check spring 66.
At the position where the base end surface 31c of the intake valve 31 is in contact with the inner wall surface 60a of the plug 60, the piston 63 is maintained in the state shown in FIG. The spring biasing force of the set spring 67 also acts between the valve portions 31b of the valve 31.

In the case of this embodiment, in the non-braking state, the hydraulic pump 2
3 is not operating, but as mentioned above relief valve 2
The liquid passage 20 that communicates between the liquid passage 21 and the valve chambers 18 and 19 in which the relief spring 2
Brake fluid is supplied with hydraulic pressure equal to the load of 2f,
Moreover, since the first traction valve TCV 1 is closed, a hydraulic pressure corresponding to the load of the relief spring 22f is acting on the valve chamber 18.19. Therefore, as shown in FIG. 5, hydraulic pressure is applied to the end surface 63c of the piston 63 opposite to the end surface 63b, and the piston 63 holds the intake valve 31 on the valve seat surface 63a by the spring biasing force of the check spring 66. While keeping this position, it moves toward the opening 16 against the biasing force of the set spring 67, and
The end surface 63b is in contact with the wall surface 61a of the piston chamber 61.

Therefore, the intake valve 31 is in a state where its tip portion 31a protrudes into the opening 16.

Next, during normal braking, anti-lock control, or traction braking, the valve mechanism 26 is activated when the stroke of the primary piston 3 reaches a predetermined value.
3 engages with the tip 31a of the intake valve 31, the valve mechanism maintains the state shown in FIG. 5, similar to the valve mechanism in the non-braking state.

Meanwhile, the primary piston 3 moves to the left in FIG.
When the stroke reaches a predetermined value, the intake sleeve 33 engages with the tip 31a of the intake valve 31, as shown in FIG. Because I push it down,
The valve portion 31b separates from the valve seat surface 63a of the piston 63.

If the brake fluid pressure in the fluid passage 21 is high at that time, brake fluid is supplied into the fluid pressure chamber 5.

Next, regarding the operation of the brake fluid pressure control device shown in Fig. 8,
This will be explained with reference to FIG. 9 and FIG.

Figure 8 shows changes in brake fluid pressure during normal braking and subsequent antilock control (traction valve TCv1, traction valve TCV2, hold valve HVI, HV2, decay valve DVI, DV2).
and a timing chart showing the opening and closing states of cut valves CVI and CV2. Note that, in reality, the hydraulic pressures of the two brake systems are controlled independently, but for the sake of simplicity, the explanation here will be based on the assumption that both systems operate at the same time.

(A) During normal braking (Fig. 8 t.-td As shown in Fig. 1, traction valve TCV 1 is 0FF (closed), traction valve TCV 2 is 0FF (
open), hold valves HVI and HV2 are 0FF (open)
When the brake pedal 37 is depressed with the decay valves DV, 1, and DV2 being 0FF (closed) and the cant valves cvi, CV2 being 0FF (open), the primary piston 3 is pushed by the bushing rod 38, causing the primary piston 3 to move as shown in FIG. moves to the left and the center valve 35 closes, and the secondary piston 4 also moves to the left and the center valve 36 closes. Therefore, a hydraulic pressure is generated in the hydraulic chamber 5.6 and is supplied to the wheel cylinder 8.9.13.14 for braking.

(B) During anti-lock control, due to an increase in the hydraulic pressure in the wheel cylinders 8.9.13.14, the system speed (the speed of the wheels to be controlled by each brake system, for example, both the front right wheel FR and the rear left wheel RL) When a deceleration of more than a predetermined value (speed by speed select low) is detected, a holding signal is generated from a control circuit (not shown) consisting of a microcomputer, and anti-lock control is started from time t1.

(1) Hold mode (Figure 8 L+-jz) Time t in Figure 8
1, the hold valves HVI and HV2 are also turned ON (closed), blocking the liquid passage 7 to the wheel cylinder 8.9 and the liquid passage 12 to the wheel cylinder 13.14, so the wheel cylinder 8.9.13.14 The hydraulic pressure inside is maintained. In this case, the valve mechanism 26.27 is in the state shown in FIG.
2a respectively protrude into the hydraulic chambers 5.6. At this time, the intake sleeves 33 and 34 are connected to the intake valve 3.
1.32 is in a position where it can be pressed down, the valve mechanism 26.27
The state is as shown in FIG. 6, and high-pressure brake fluid flows from the hydraulic pump 23 into the hydraulic chamber 5.6 through the hydraulic passage 21.20. This brake fluid pressure causes the piston 3.4 to move the intake sleeve 33.34 toward the intake valve 3.
1.32 is released, and the hydraulic pressure in the hydraulic pressure chamber 5.6 becomes proportional to the depression force of the brake pedal 37. In this case, the intake sleeve 33.34 pushes down the intake valve 31.32 and communicates the hydraulic chamber 5.6 with the discharge port of the hydraulic pump 23 due to the position of the briny piston 3 and the secondary piston 4,
The hydraulic pressure discharged from the hydraulic pump 23 causes the piston 3.4 to move the intake valve 31.32 into the opening 16.
．． 17 is pushed back until it closes.

Therefore, even if a failure occurs in the hydraulic pressure source system,
Sufficient hydraulic pressure can be ensured within the hydraulic pressure chamber 5.6.

(2) Depressurization mode (Fig. 8 j 2 = j 3) When the system speed further decreases, the decay valve DV starts from time t2.
I, DV2 is turned ON (open), and this causes the brake fluid in the wheel cylinder 8.9.13.14 to flow into the fluid passage 10.
．． It flows into the reservoir 11 through 15 and is depressurized.

(3) Hold mode (Fig. 8 t3 → ta) Decay valves DVI and DV2 turn 0FF at time t3 when the system speed begins to recover after passing through a low peak due to the above brake fluid pressure reduction.
(closed) and returns to holding mode.

(4) Pressure mode (Fig. 8 ta-ts) When the system speed reaches a high peak, hold valves HVI and HV2 are set to 0.
FF (open), the piston 3.4 moves and the intake valve 31.32 opens, and the hydraulic pressure from the hydraulic pump 23 passes through the hydraulic chamber 5.6 to the wheel cylinder 8.9.1.
3.14. In the pressurization mode starting from time t4 in FIG. 8, hold valves HVI, HV2
The brake fluid pressure increases stepwise by turning ON and OFF in small increments.

(5) Holding mode (Fig. 8j, -t6) When the system speed starts to decrease due to increased brake fluid pressure, the holding mode is entered again, and hold valves HVI and HV2 are set to 0FF (closed).
become. Then, at time t6, the decay valves DVI, DV
2 is turned ON (open) and the pressure reduction mode returns.

(C) Drive wheels FR and FL when the vehicle starts or accelerates during traction control
In the case of traction control to prevent slippage, a control circuit (not shown) consisting of a microcomputer enters the pressurization mode from the time when slipping of the drive wheels FR, FL is detected (time tI+> in FIG. 9).

(1) Pressure mode (Figure 9 tll → t, 2) At time t11 in Figure 9, cut valves CVI and CV2 are turned on (
(closed), traction valve TCVI is turned ON (open), and traction valve TCV2 is turned ON (closed). Therefore, communication between the wheel cylinders 9.14 of the driven wheels RL and RR and the hydraulic pressure chamber (main hydraulic chamber) 5.6 of the master cylinder 1 and communication between the auxiliary hydraulic pressure chamber 54 and the reservoir 11 are both cut off. . Furthermore, since the traction valve TCV1 is ON (open), the auxiliary hydraulic pressure chamber 54 communicates with the discharge port of the hydraulic pump 23, so that the pressure inside the auxiliary hydraulic pressure chamber 54 increases and the auxiliary piston 53 moves as shown in FIG. Move to the left. Therefore, the primary piston 3 is pressed by the auxiliary piston 53 and moves to the left, so that the brake fluid pressure in the wheel cylinder 8.13 increases and enters the pressurization mode.

Note that for a predetermined time ΔT after traction control is started at time t11, the hold valves HVI and HV
2 is set to 0FF (open), pre-pressurization is performed during this time, and then hold/sl lube HVI and HV2 are turned on.
(closed) and brake fluid pressure is maintained. And after this, the hole tonneau < lube HVI, HV2 is gradually 0N=O
By being turned off, the brake fluid pressure increases stepwise.

(2) Holding mode (time t1□-t, 3 in Figure 9) From the time t1□ when the pickpocket knobs of drive wheels FR and FL become weak, the halt valves HVI and HV2 are turned ON (closed) and the holding mode is activated. Become.

(3) Decompression mode (Figure 9 time tll → t+a) time t
Decay valves DVI and DV2 are turned ON (open) from 11 to enter the pressure reduction mode, and thereafter each mode is repeated in the same manner as the anti-lock control.

By the way, in this case, the auxiliary piston 53 receives the hydraulic pressure in the auxiliary hydraulic pressure chamber 54 equal to the hydraulic pressure discharged from the hydraulic pump 23 at its annular pressure receiving step portion 53b, and also,
Since the hydraulic pressure in the hydraulic pressure chamber 5 is applied to the primary piston 3 over an area approximately equal to the cross section of the hydraulic pressure chamber 5, here, the pressure receiving area of the primary piston 3 is AM, and the pressure receiving area of the auxiliary piston 53 is If the hydraulic pressure discharged from the hydraulic pump 23 is PA, then the hydraulic pressure PH in the hydraulic chamber 5 when the intake valve 31 is closed is determined by the following equation.

A PM = x P t+ AM In other words, the hydraulic pressure PH in the hydraulic pressure chamber 5 is the pressure receiving area ratio A + i
/ A x, and this ratio can be set by 1
By setting smaller the wheel cylinder 8.1
3 is made weaker than the hydraulic pressure P from the discharge port of the hydraulic pump 23, thereby preventing vibrations caused by traction control and enabling smooth traction control. This prevents a large load from being placed on the drive system.

(Effects of the Invention) As is clear from the above explanation, in the present invention, by employing the relief valve 22, a large capacity accumulator is not required, and the relief spring 22 is not required.
Since the discharge hydraulic pressure of the hydraulic pump 23 is determined by 2f, it is possible to absorb the impact pressure generated when the brake fluid is discharged from the hydraulic pump 23, and it is possible to reduce the occurrence of operating noise, vibration, etc. A small, lightweight, and inexpensive device can be provided. In addition, by adopting the switch 70, the hydraulic pump 23
By monitoring the presence or absence of brake fluid pressure on the discharge side of the intake sleeve 33, it is possible to determine whether the hydraulic pump function is normal or not. By pushing down the intake valve 31, high-pressure brake fluid is supplied into the hydraulic pressure chamber 5, which activates the switch 70 and drives the hydraulic pump 23. This prevents an increase in the pedal stroke and prevents the brake fluid from increasing when the vapor is locked. It is also possible to secure braking force.

Furthermore, since the pawl valve 22c is configured to sit in the direction in which the brake fluid escapes when the valve is opened, the sealing performance is extremely good, and the piston 22a maintains a balanced hydraulic pressure due to the relief spring 22f. Therefore, during the relief operation, the hydraulic pressure in the liquid passage 21 does not decrease, and stable hydraulic pressure can be supplied.

In addition, in this embodiment, the normal intake valves 31 and 32
The only hydraulic pressure acting on the valve is the biasing force of the relief spring 22f, and no high hydraulic pressure is applied, improving the durability of seals and the like, and providing good responsiveness during traction operation.

Furthermore, in this embodiment, the valve part of the intake valve 31.32 and the valve seat surface of the piston form a seal part from the hydraulic pressure chamber 5.6 side of the liquid passage 20.21 and from the discharge port side of the hydraulic pump 23. Since the seal portion is formed, the reliability of the seal portion is also good.

Further, in this embodiment, since the intake valves 31, 32 are provided with a sabot section on the outer circumferential surface, there is an advantage that the intake valves 31, 32 operate extremely smoothly without twisting during operation.

[Brief explanation of drawings]

FIG. 1 is an overall configuration diagram of a brake fluid pressure control device according to an embodiment of the present invention, FIG. 2 is an enlarged vertical sectional view of its valve mechanism, and FIG.
Figure 4 shows the ■■ line and IV-IV in Figure 2, respectively.
5 and 6 are longitudinal sectional views for explaining the operation of the valve mechanism shown in FIG. 2, FIG. 7 is an enlarged view of the main parts of the device shown in FIG. 1, and FIG. 8 is a cross-sectional view along the line. 1 is a timing chart for explaining anti-lock control by the device shown in FIG. 1, and FIG. 9 is a timing chart for explaining traction control by the device shown in FIG. 1-Master cylinder 3-Primary screw 4-Secondary piston 5.6-hydraulic pressure chamber 8.9.13.14-Wheel cylinder 11-reservoir 18.19-=valve chamber 22-relief valve 23-hydraulic pressure Pump 31. 33. 35, 32 - Intake valve 34 - Intake sleeve 36 - Center pulp brake pedal auxiliary piston 54 Auxiliary fluid pressure chamber piston switch Attorney: Toshihito Yamamoto, patent attorney

Claims (1)

[Claims] A hold valve and a decay valve are provided for pressurizing, maintaining, or reducing brake fluid pressure during anti-lock control or traction control, and the hold valve is connected to the master cylinder's fluid pressure chamber and the wheel cylinder. In the brake fluid pressure control device, the decay valve is provided in a second fluid passage connecting the wheel cylinder and the reservoir, and the decay valve is provided in a second fluid passage connecting the wheel cylinder and the reservoir. a third liquid passage connecting the discharge port of the pressure pump; and an intake valve provided at an opening of the third liquid passage communicating with the hydraulic pressure chamber and normally blocking the third liquid passage. , is provided on the piston so as to be able to move integrally with the piston of the master cylinder, and when the stroke of the piston reaches a predetermined value, engages with the intake valve to open the intake valve. a valve operating member; a piston that receives hydraulic pressure in the third liquid passage between the discharge port of the hydraulic pump and the intake valve and hydraulic pressure in the hydraulic pressure chamber of the master cylinder from mutually opposite directions; a valve body that is provided within the piston and moves together with the piston, and when the brake fluid pressure in the third fluid passage rises above a predetermined value, the valve body is opened by the movement of the piston, and the valve body is opened by the movement of the piston. 3. A relief valve configured to release the brake fluid in the fluid passage to the reservoir, and a switch that stops the operation of the motor that drives the hydraulic pump in response to the movement of the piston to a predetermined position. A brake fluid pressure control device comprising: