JPH03287437A - Braking circuit with anti-lock device - Google Patents

Abstract

PURPOSE:To reduce the pulsation of a pump transmitted to a brake pedal through a master cylinder by forming a braking circuit in such a way that operating liquid returned to the master cylinder side by the pump through a reflux passage at the time of anti-lock pressure reduction passes a throttling by-pass passage of minimized flow area. CONSTITUTION:When anti-lock pressure reduction is started, a solenoid valve 5 is opened, so that operating liquid in the pressure reducing chamber 26 of a flow control valve 4 is discharged onto a reflux passage L2 side from a second outlet 21d and flows into a reservoir 13 through the solenoid valve 5. The operating liquid stored in the reservoir 13 flows back to a feedback point P2 through the reflux passage L2 by the operation of a pump 6 driven by a motor 14. In this case, a first check valve 10 is provided at a main passage L1 on the master cylinder 2 side so as to block the flow and return the operating liquid onto the master cylinder 2 side through a throttling by-pass passage 11. The transmission of the pulsation of the pump 6 to the master cylinder 2 is thereby reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a brake circuit equipped with an anti-lock device, and more specifically to a brake circuit equipped with an anti-lock device, which discharges hydraulic fluid from a wheel brake into a recirculation path during an anti-lock operation, and a brake circuit provided in the recirculation path. This invention relates to a recirculation type anti-lock device in which the pump circulates the flow to the master cylinder side, and to a device that prevents pump pulsation from being transmitted to the mask noring side when the pump is operated.

BACKGROUND OF THE INVENTION Conventionally, in this type of recirculation type anti-lock device, a) a main flow path is branched from the main flow path connecting the master cylinder and the wheel brake, and the flow path is connected to the main flow path on the upstream side of this branch point (i.e., on the master cylinder side). a recirculation path that returns the hydraulic fluid to a certain return point; b) a pump installed in the recirculation path that recirculates the hydraulic fluid; and C) braking of the wheel brakes by discharging the hydraulic fluid from the branch point to the recirculation path. Adopts a system that has a pressure regulating means that reduces the pressure and also supplies hydraulic fluid from the main flow path downstream of the return point to the wheel brakes via the branch point to increase the brake pressure of the wheel brakes. are doing.

In the device employing the above-mentioned reflux type, for example, as disclosed in Japanese Patent Publication No. 61-33738, as the pressure regulating means, an electromagnetic actuator is applied to the main flow path between the return point and the branch point. A normally open hydraulic pressure supply valve is provided, and an electromagnetically operated normally closed hydraulic discharge valve is provided in the return path between the branch point and the pump. Brake fluid pressure during anti-lock is controlled using three modes: holding and pressurizing.

However, in the above-mentioned recirculation type anti-lock device, the hydraulic fluid discharged from the wheel brake when the anti-lock pressure is reduced is returned to the master cylinder side by the pump, so it is susceptible to brake pedal vibration and piping system vibration due to pump pulsation. Problems such as noise are occurring.

Various methods have been proposed to reduce the transmission of the pump pulsation to the master cylinder side. For example, in the device disclosed in Japanese Patent Publication No. 61-33738 mentioned above, a first check valve is provided between the return point and the hydraulic pressure supply valve with the direction of the supply valve being the forward direction, and a wheel brake A second check valve whose forward direction is in the direction of the master cylinder is provided in the bypass flow path from the to the master cylinder, and a reservoir is provided between the hydraulic pressure discharge valve of the return flow path and the pump,
Further, an accumulator and a throttle passage that bypasses the first check valve and communicates with the main flow path downstream of the return point are provided downstream of the pump discharge port.

In the above device, the pressure of the brake fluid discharged from the pump is accumulated in an accumulator, and the brake fluid is allowed to flow from the accumulator little by little to the master cylinder side through the throttle passage, thereby reducing the transmission of pump pulsation to the brake pedal. ing.

Problems to be Solved by the Invention As described above, in the conventional device, during anti-lock, the brake fluid in the wheel brake is discharged without flow rate control via a hydraulic discharge valve consisting of an electromagnetic on-off valve. Therefore,
If the entire amount of brake fluid discharged from the pump installed in the recirculation path passes through the throttle passage, the discharge pressure of the pump will increase and the load on the pump will increase. It has a structure that allows the liquid to pass through the narrow passage little by little.

Therefore, in addition to providing a reservoir, a pump, and a throttle passage, it is necessary to install a large accumulator in the reflux path, which complicates the structure, takes up space, increases size, and increases costs. there were.

The present invention aims to solve the above-mentioned problems, and in order to effectively suppress the transmission of pump pulsation to the master cylinder side, and to simplify the structure and reduce costs, the present invention has been developed using conventional methods for hydraulic pressure control. By replacing the two required solenoid valves with one solenoid valve and a flow control valve, and by providing the flow control valve, the amount of brake fluid in the recirculation path is reduced during anti-lock, thereby reducing the amount of brake fluid in the recirculation path. This eliminates the need for an accumulator, which was required in the past.

Means for Solving the Problems Accordingly, the present invention branches from the main flow path connecting the master cylinder and the wheel brake, and connects the main flow path from a first return point upstream of this branch point (i.e., on the master cylinder side). a recirculation path for returning the hydraulic fluid; a pump provided in the recirculation path for recirculating the hydraulic fluid; In the brake circuit equipped with an anti-lock device having pressure regulating means for increasing the brake pressure of the wheel brakes by supplying hydraulic fluid from the main flow path to the wheel brakes, the main flow path between the master cylinder and the first return point is A first check valve whose forward direction is a direction from the master cylinder toward the first return point, and a throttle bypass flow path having a small flow path cross-sectional area connecting upstream and downstream of the first check valve are provided in the passage. Also, a bypass flow path connecting a second return point upstream of the first return point of the main flow path and the wheel brake, and a second return point in the bypass flow path.
A second check valve is provided whose forward direction is toward the return point, and the pressure regulating means includes a flow control valve provided at a branch point of the main flow path and a normally closed check valve provided upstream of the pump in the return flow path. The anti-lock device comprises a solenoid valve that opens when the anti-lock pressure is reduced, and the flow control valve is configured to control the flow rate of hydraulic fluid from the wheel brakes and discharge it to a recirculation path when the anti-lock pressure is reduced. A brake circuit equipped with a device is provided.

Function As mentioned above, the hydraulic fluid that is returned to the master cylinder side by the pump through the recirculation path during anti-lock pressure reduction passes through the throttle bypass passage with a small flow path area, so it is transferred to the brake pedal via the master cylinder. Transmitted pump pulsations can be reduced. Furthermore, since the hydraulic fluid for the wheel brakes is discharged into the recirculation path through the flow control valve during anti-rotation, an accumulator for temporarily accumulating the pressure of the hydraulic fluid discharged from the pump can be eliminated.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to embodiments shown in the drawings.

In the figure, 1 is a brake pedal, 2 is a master cylinder operated according to the pressing force of brake pedal 1, 3 is a wheel brake, and Ll is the master cylinder 2 and wheel brake 3.
The main flow path L2 that connects the main flow path L2 is a reflux path that branches from the main flow path Ll at a branch point P1 and joins the main flow path Ll at a first return point P2 upstream from the branch point PI (i.e., on the master cylinder side), and L3 is A bypass flow path 4 branches off from the branch point P2 of the main flow path L1 (i.e., on the wheel brake side) and joins the main flow path Ll at a second return point P3 on the upstream side of the return point P2 of the main flow path Ll. A flow control valve is provided at the branch point P2 of the main flow path Ll, 5 is a solenoid valve provided in the recirculation path L2, and 6 is a pump for recirculating the working fluid provided with the solenoid valve 5 and the return point P2 in the recirculation path L2.

A first check valve 10 whose forward direction is in the direction of the first return point P2 is provided between the second return point P3 and the first return point P2 of the main flow path L1.
In addition, a throttle bypass flow path 11 with a small flow path cross-sectional area connecting the upstream and downstream of the first check valve IO is provided. The narrowing bypass flow path 11 is narrowed in the range of 1710 to 115 with respect to the main flow path Ll.

Further, a second check valve 12 whose forward direction is directed toward the second return point P3 is interposed in the bypass passage L3. The opening pressure of both the first check valve 10 and the second check valve 12 is set to be low. Therefore, when a slight pressing force is applied to the brake pedal 1 when applying brake pressure, the first check valve lO opens due to the hydraulic fluid pressure from the master cylinder 2 side, and the hydraulic fluid flows into the wheel brake 3 via the flow control valve 4. On the other hand, when the brake pressure is reduced, the second check valve 12 of the bypass flow path L3 opens and the hydraulic fluid is returned to the master turn cylinder 2. It should be noted that when the brake pedal is pressed to apply brake pressure, the throttle bypass flow path 11 is
Since the hydraulic fluid is sent to the wheel brake 3 side through , the effectiveness of the brake does not deteriorate.

The solenoid valve 5 installed in the recirculation path L2 is normally closed, and when the anti-lock pressure is reduced, it is automatically opened by electromagnetic operation to discharge the hydraulic fluid from the wheel brake 3 to the recirculation path L2 via the flow control valve 4. , the wheel brakes 3 are being depressurized. on the other hand,
When the brake pressure is reapplied, the solenoid valve 5 closes to cut off the discharge to the recirculation path L2, and supplies hydraulic fluid from the main path Ll to the wheel brakes 3 via the flow control valve 4 to apply the wheel brakes. The flow rate control valve 4 and the solenoid valve 5 constitute pressure regulating means for the hydraulic fluid.

The reflux path L2 includes a reservoir 13 downstream of the solenoid valve 5.
is installed, and the pump 6 driven by a motor 14 is installed downstream of the reservoir 13.

Check valves 15 and 16 are provided between the pump 6 and the reservoir 13 and between the pumps and the return point P2, respectively, to allow the working fluid discharged into the return path L2 to flow back only in the direction from the branch point PI to the return point P2. There is.

The structure of the flow rate control valve 4 constituting the pressure regulating means will be described in detail below.A spool 22 is fitted into a hole 21a formed in a handheld puffer 21 so as to be slidable in the axial direction. On the side of the Hanji Puffer 21, there is an inlet 21b connected to the return point P2 side of the main flow path Ll, and a first outlet 21 connected to the wheel brake side.
c, and exits 21e and 21 provided branching off from the first exit.
f, and a second one connected to the reflux path L2 on one end surface.
An exit 21d is provided.

The spool 22 has a first liquid passage 25A and a second liquid passage 25B formed in the axial direction with an orifice 23 in between. Further, an outer peripheral groove 2 is provided at a position close to the inlet 21b.
2a, and a radial flow path 22 communicating with the outer circumferential groove 22a.
At the same time as drilling b, at a position across the orifice 23,
Outer circumferential groove 22c, radial flow path 22d, outer circumferential groove 22e
A radial flow path 22f is bored. Above outer circumferential groove part 2
2a, 22c, and 22e according to the movement of the spool 22,
The inlet 21b1 communicates with and is cut off from the first outlets 21e and 21f, and its outer open end is a metal edge. The tip of the spool 22 is formed as a spring receiver 22g, and the hole 21
A return spring 24 is compressed between the one end surface of a. A hole 21a that serves as a receiving surface for the return spring 24
The second outlet 21d is bored at one end, so that the second outlet 21d is communicated with a decompression chamber 26 provided at one end of the spool 22.

Next, to explain the operation of the above embodiment, FIG. 1 shows a normal braking state, that is, a non-antilock state, and the hydraulic fluid is supplied from the master cylinder 2 side to the main flow path Ll to the first check valve lO and the throttle. It is guided to the inlet 21a of the flow control valve 4 via the bypass passage 11. Note that the hydraulic fluid from the main flow path Ll is blocked by the second check valve I2 and the check valve 16, and does not flow into the bypass flow path L3 and the reflux path L2.

In the non-anti-lock state, the flow control valve 4 has a spool 21
is biased by the return spring 24 and is at the upper end position in the figure, and the flow path 22b is connected from the inlet 21b to the outer circumferential groove 22a-b.
→Liquid passage 25A→Flow path 22d-Outer circumferential groove 22c→A large flow path leading to first outlets 21e and 21b is secured. Therefore, hydraulic fluid corresponding to the depression force on the brake pedal 1 is sent from the master cylinder 2 to the wheel brakes 3 via the first check valve 10 and the large flow path of the flow control valve 4 to pressurize the brakes.

In addition, during normal brake operation, the opening pressure of the first check valve lO is set small, and the hydraulic fluid is sent to the flow rate control valve 4 side via the throttle bypass flow path 11 until the valve opens. Also in the flow rate control valve 4, since a large flow path is ensured as described above, problems such as a delay in brake effectiveness and a delay in brake return do not occur.

On the other hand, when the anti-lock pressure reduction starts, the solenoid valve 5 is opened, and in the flow control valve 4, the hydraulic fluid in the pressure reduction chamber 26 is discharged from the second outlet 21c to the reflux path L2 side, and the solenoid valve 5 is opened. Then it flows into the reservoir 13. In the flow control valve 4,
Due to the outflow of the working fluid from the decompression chamber 26, the orifice 23
A pressure difference is generated between both ends of the spool 22, and the spool 22 moves downward in the figure. When moved to the position shown in FIG. 2, the edge 23h of the outer circumferential groove 23c
The communication between the i section 23c and the first outlet 21e is cut off, and the large flow path is closed. Further, the spool 22 moves downward, and as shown in FIG. 3, the edge 23i opens and communicates with the outer circumferential groove 23e and the first outlet 21f. Therefore, first outlets 21c, 21f→outer WIt portion 22e-flow path 22f→
The decompression flow path from the decompression chamber 26 to the second outlet 21d communicates with each other,
The working fluid for the wheel brakes 3 is discharged into the reflux path L2 and stored in the reservoir 13. The pump 6 is driven by the motor 14, and the hydraulic fluid stored in the reservoir 13 is transferred to the reflux path L.
2 and returns to the return point P2. It flows into the main flow path L1 from the return point P2, and since the inlet 21b on the downstream flow control valve 4 side is closed as shown in FIG.
The main flow path L1 on the master cylinder side is provided with a first check valve 10 to block the flow. After that, it is returned to the master cylinder 2 side. The throttle bypass flow path ti is connected to the main flow path L as described above.
Since the cross-sectional area of the flow path is sufficiently narrowed compared to 1, transmission of the pulsation of the pump 6 to the master cylinder 2 is reduced.

Further, during the anti-lock pressure reduction, the flow rate of the hydraulic fluid discharged to the reflux path L2 is controlled. That is,
When the inlet 2ta and the outer periphery 111122a are in communication until the first outlet 21f and the outer circumferential groove 22g communicate with each other, the hydraulic fluid flows from the decompression chamber 26 through the orifice 23 to the second
Since the working fluid is discharged to the outlet 21d through the small flow path, the flow rate of the working fluid discharged to the reflux path L2 is small. Moreover, the spool 22 moves, and the first outlet 31f and the outer circumferential groove 32
Even when g is communicated, the fluid is discharged while the flow rate is controlled by the variable orifice formed by the edge 32i. Therefore, compared to the case where the hydraulic fluid is discharged from the wheel brake to the recirculation path by opening the solenoid valve as shown in the conventional example described above, the hydraulic fluid is not discharged to the recirculation path more rapidly. Therefore,
There is no need for an accumulator to accumulate pressure of the hydraulic fluid discharged from the pump.

When the anti-lock is pressurized again, the electromagnetic valve 5 is de-energized, and the flow of hydraulic fluid from the second outlet 21d is stopped. In the state shown in FIG. 3, a variable orifice consisting of a population 21b and its edge 22, outer circumferential groove 22a - flow path 22b -> first liquid passage 25A - orifice 23 -> second liquid passage 25El -> flow path 22f -> first Small channels leading to the outlets 21f and 21c are ensured.

In this case, the opening angle of the variable orifice 23 in the edge 22 is automatically adjusted so that the flow rate is always constant regardless of the differential pressure between the inlet 21b and the first outlet 21c. That is, the biasing force due to the differential pressure generated before and after the orifice 23 and the biasing force of the return spring 24 are balanced, and this differential pressure has a constant value determined by the biasing force of the spring 24 and the effective cross-sectional area of the spool 22. to be maintained. Therefore, by reducing the biasing force of the spring 24, a small flow rate can be ensured in the relatively large diameter orifice 23, and the repressurization speed during anti-lock can be reduced.

In addition, during the repressurization, a part of the liquid discharged from the pump 6 passes from the return point P2 to the flow control valve 4 to the wheel brake 3.
is supplied to In this way, since the entire discharge amount of the pump 6 does not pass through the throttle bypass passage ll, the pump 6
There is no problem of additional increase.

It should be noted that the present invention is not limited to the above-mentioned embodiments, but is shown in FIGS. 4 to 6.
It is also possible to use a flow control valve 4' having a structure as shown in the figure.

The flow rate control valve 4' has an inlet 31a that communicates with the master cylinder side, and a first outlet 31b1 that communicates with the wheel brake 3.
A spool 32 for switching the communication state between the boats is slidably housed inside the Hanji Puffer 31 which has three boats at the second outlet 31c communicating with the reflux path L3 and is biased by a spring 34. .

In this device, when the anti-lock is not activated, the spool 32 remains at the original position shown in FIG. 4, forming a large flow path from the inlet 31a to the outlet 31b via the outer circumferential groove 32a of the spool 32.

Furthermore, when the anti-lock pressure is reduced, when the solenoid valve 5 opens, the hydraulic fluid is discharged from the second outlet 31c to the reservoir 13, and as a result, the spool 32 moves with a pressure difference generated at both ends, resulting in the state shown in FIG. Become. Then, first, the large flow path is closed at the large flow path 1 part 32b of the spool 32, and the spool 32 further moves to the state shown in FIG. 6, where the small flow path closing portion 32
c is in the open state and the outlet 31b, groove 3281 passage 31
A discharge path connecting the e1 second outlet 31c is formed, and the solenoid valve 5
The hydraulic fluid for the wheel brakes 3 is discharged to the reservoir 13 and depressurized. When the hydraulic fluid is discharged to the recirculation path L2, the hydraulic fluid of the wheel brake 3 is discharged to the recirculation path L2 while being controlled according to the movement of the spool 32, that is, the open state of the small flow path closing portion 32c. Therefore, similarly to the embodiment described above, it is possible to prevent the entire amount of the working fluid of the wheel brake from being rapidly discharged to the recirculation path L2 during anti-lock pressure reduction.
Therefore, pump pulsation transmitted to the brake pedal can be sufficiently suppressed by simply passing the fluid discharged from the pump 6 through the throttle bypass passage without accumulating the pressure in the accumulator.

Effects of the Invention As is clear from the above explanation, according to the present invention, a reflux system is employed in which the working fluid is discharged from the wheel brakes into the reflux path during anti-lock, and is refluxed to the master cylinder side by a pump provided in the reflux path. In the anti-lock device, the main flow path of the hydraulic fluid connecting the master cylinder and the wheel brake is provided between the master cylinder and a return point where the main flow path and the above-mentioned return flow path merge, with the direction of the return point being the forward direction. A first check valve and a throttle bypass flow path that bypasses the first check valve are provided, and the pump discharge liquid returns to the master cylinder side through the throttle bypass flow path, so that the pump discharge occurs when the pump is operated. The transmission of pulsations to the brake pedal via the master cylinder can be reduced. In addition, in the present invention, a flow rate control valve and a normally closed solenoid valve that opens only when the anti-lock pressure is reduced are provided as the hydraulic fluid pressure regulating means, and the flow rate of the hydraulic fluid discharged to the reflux path when the anti-lock pressure is reduced. is under control. Therefore, the entire amount of working fluid is not rapidly discharged to the reflux path, and there is no need to provide an accumulator to temporarily accumulate the pump discharge pressure. can be effectively reduced and suppressed.

In addition, the opening pressure of the first check valve provided in the main flow path and the second check valve provided in the bypass flow path is set low, and the first check valve has a small flow path cross-sectional area as described above, but the opening pressure is set low. Since the brake is provided with a bypass flow path, it also has the advantage of preventing problems such as a delay in brake effectiveness during normal brake operation and failure to return to the vehicle.

[Brief explanation of the drawing]

FIG. 1 is an overall configuration diagram showing an embodiment of the present invention, FIGS. 2 and 3 are sectional views showing the operation of the flow control valve in FIG. 1, and FIG. 4 is a diagram showing another embodiment of the present invention. The overall configuration diagram, FIGS. 5 and 6 are sectional views showing the operation of the flow control valve used in FIG. 4. l...brake pedal, 2...master cylinder,
3...Wheel brake, 4...Flow control valve, 5...
・Solenoid valve, 6...pump, lO...1st
Check valve, 11... Restriction bypass flow path, 12... Second check valve, 13... Reservoir, Ll... Main flow path, L2... Reflux path, L3... Bypass flow Road, Pi... Branching point, P2... First return point, P3
...Second return point.

Claims (1)

[Claims] 1. Branching from the main flow path connecting the master cylinder and wheel brakes, and returning the hydraulic fluid to the main flow path from a first return point upstream of this branch point (i.e., on the master cylinder side) a recirculation path; a pump provided in the recirculation path for recirculating the hydraulic fluid; and a pump for discharging the hydraulic fluid from the wheel brake to the recirculation path to reduce the brake pressure of the wheel brake; In the brake circuit equipped with an anti-lock device having pressure regulating means for increasing the brake pressure of the wheel brakes by supplying hydraulic fluid to the brake circuit, the master cylinder is connected to the main flow path between the master cylinder and the first return point. A first check valve whose forward direction is in the direction toward the first return point, and a throttle bypass flow path having a small flow path cross-sectional area connecting upstream and downstream of the first check valve, and the main flow path a bypass flow path connecting a second return point upstream of the first return point and the wheel brake;
A second check valve is provided whose forward direction is toward the return point, and the pressure regulating means includes a flow control valve provided at a branch point of the main flow path and a normally closed check valve provided upstream of the pump in the return flow path. The anti-lock device comprises a solenoid valve that opens when the anti-lock pressure is reduced, and the flow control valve is configured to control the flow rate of hydraulic fluid from the wheel brakes and discharge it to a recirculation path when the anti-lock pressure is reduced. Brake circuit with device.