JPH07277171A - Brake fluid pressure control device - Google Patents

Abstract

(57) [Summary] [Purpose] To prevent damage to the master cylinder due to the brake fluid in the reservoir of the master cylinder being sucked into the brake circuit during traction control. [Structure] A wheel brake hydraulic pressure control valve 5 is provided in the main flow passage 3, an exhaust liquid reservoir 6 for storing brake fluid discharged from the valve, and a brake fluid in the liquid reservoir 6 is returned to a return point 8 of the main flow passage 3. To the master cylinder 1, a traction control switching valve 16 that blocks the flow of liquid from the reflux point 8 to the master cylinder 1, a replenishment flow passage 11 that branches off from the main flow passage 3, and communicates with the main flow passage 3 during normal braking. Intermediate liquid reservoir 1
2 is added, a relief valve 15 is provided in the middle of the communication flow path 14 branched from the main flow path 3, and further, the liquid flow from the replenishment flow path 11 toward the intermediate liquid reservoir 12 is blocked during the execution of the traction control, and the intermediate liquid A second switching valve 13 that connects the reservoir 12 and the discharge liquid reservoir 6 is added.

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 having both an antilock function and a so-called traction function.

[0002]

2. Description of the Related Art As the simplest anti-lock device (ABS), a wheel brake hydraulic pressure control valve including a discharge valve is provided in a main flow path from a master cylinder to a wheel brake, and further, the discharge is performed through the discharge valve. There is known a so-called reflux type in which an exhaust fluid reservoir for temporarily storing the brake fluid and a pump for pumping up the brake fluid in the fluid reservoir and returning it to the main flow path are provided. When adding a traction function to this device, if the anti-lock reflux pump is used as a pressure source for traction control, the maximum effect in terms of simplification of the structure can be expected.

However, when such a method is adopted,
Brake fluid must be replenished to the suction side of the pump. There are some known examples of the supplement method. These known examples are a system in which a replenishment flow path is directly provided from the reservoir of the master cylinder to the pump suction port side,
It is classified into a method in which the supply channel is branched from the main channel that connects the master cylinder's outlet and the wheel brakes. Among these, the method of attaching to the wheel and the surplus brake fluid from the master Shinrida's inlet The latter is more advantageous considering the necessity of backflow to the reservoir.

In the latter method in which the replenishment flow path is branched from the main flow path, a traction control switching valve that blocks the flow of liquid from the reflux point from the pump toward the master cylinder during traction control, and a normal brake operation (master cylinder operation) A shutoff valve is required to block the flow of liquid from the replenishment flow path to the drainage reservoir during pressurization).

The problems of the latter method of branching from the replenishment passage are the suction resistance at the intake port of the master cylinder, the piping resistance from the master cylinder to the brake fluid pressure control device, and the replenishment passage at the time of normal braking. There is a possibility that the brake fluid supply flow rate to the pump will be limited due to the resistance inside the shutoff valve that is closed, and the rise of brake fluid pressure at the initial stage of traction control may be delayed. Some have an intermediate liquid reservoir.

[0006]

The problems of the method of providing the intermediate liquid reservoir communicating with the replenishing flow passage are as follows.

The intermediate liquid reservoir is constructed so that when the internal liquid pressure of the intermediate liquid reservoir is lower than the atmospheric pressure, the volume of the liquid reservoir is reduced by the pressure difference between the inside and the outside to keep the internal liquid pressure at a value close to the atmospheric pressure. Has been done. Further, when the traction control is finished, the spring force and the elastic restoring force of rubber or the like restore the volume expansion side which is the initial state.

Therefore, when the traction control takes a long time, the intermediate liquid reservoir tries to return to the volume expansion side, so that the intermediate liquid reservoir brakes from the reservoir of the master cylinder through the replenishing flow path even during the traction control. Inhale the liquid.

If the driver brakes while the suction is occurring, the brake fluid is equal to or more than the brake fluid amount sent to the brake circuit corresponding to the amount of the brake pedal entry when the normal brake operation is performed. The state sent to the circuit appears.

When the driver releases his foot from the brake pedal after falling into this state, due to the high-pressure liquid trapped in the brake circuit, in the conventional type master cylinder, when the cup seal in the cylinder passes through the side port. In addition, the center valve type master cylinder has a problem in that the rubber seal of the center valve is galled.

Such a problem may occur in the master cylinder of the conventional type or center valve type single master cylinder, conventional + conventional, center valve + center valve, center valve + conventional tandem master cylinder. This also occurs in master cylinders of the type (for example, tilt valve type).

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems of the conventional device, an object of the present invention is to prevent the brake fluid from being unnecessarily fed into the brake circuit even if the brake pedal is depressed during traction control. That is.

[0013]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides an intermediate liquid reservoir which is communicated with a main flow passage at least during normal braking, on a supply flow passage of a brake hydraulic pressure control device having a traction control valve. In addition, a configuration is adopted in which a second switching valve is provided between the replenishment flow path and the drainage reservoir to block communication between the replenishment flowpath and the drainage reservoir during traction control.

In such a brake device, when the intermediate liquid reservoir is of the above-mentioned volume expansion type, that is, when the internal liquid pressure of the intermediate liquid reservoir becomes equal to or lower than the atmospheric pressure, the volume of the liquid reservoir is reduced and Keep the fluid pressure close to atmospheric pressure, keep the volume of the intermediate reservoir smaller than the initial position, connect the flow passage from the replenishment passage to the intermediate reservoir, and check the hydraulic pressure from the master cylinder reservoir. Acts as an internal hydraulic pressure, when it increases the volume of the intermediate liquid reservoir,
Particularly effective effect.

The traction control switching valve and the second switching valve may be electromagnetic valves or pressure-responsive switching valves triggered by the master cylinder pressure.

Further, the relief valve provided in the middle of the communication passage is preferably a two-position switching valve which takes the relief valve position when the traction control is performed and takes the fully opened position of the passage when the master cylinder is pressurized. Further, the relief valve for switching between the two positions may be a solenoid valve. If the relief valve position is set only when traction control is performed by using the two-position switching electromagnetic relief valve, or if the configuration is such that the flow passage is fully opened for a certain period of time at the end of traction control, there is a concern described in the embodiment. It can be lost.

[0017]

During the traction control, the second switching valve completely shuts off the communication between the pump suction port and the replenishment passage.

Therefore, the pump sucks the liquid only from the intermediate liquid reservoir and the discharge liquid reservoir, and does not suck the liquid from the reservoir of the master cylinder.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a case of a three-position control ABS in which a main flow path and a supply flow path are always in communication, and a traction control switching valve is provided with a branch point between the main flow path and the supply flow path and a return point from a pump. The example is a 2-port 2-position valve provided between the two.

The master cylinder 1 operated by the brake pedal (which can be combined with an arbitrary booster) has two discharge ports, but since both systems are completely symmetrical, the first cylinder is used here. Only the system will be described.

A wheel brake hydraulic pressure control valve 5 including a discharge valve in the middle of a main flow path 3 connecting the discharge port 2 and the wheel brake 4
Is provided. The wheel brake hydraulic pressure control valve may be a three-position type as shown in the figure that performs pressurization, holding, or depressurization, or may be a two-position type without a holding position. Also,
A check valve is often added in parallel to this control valve (not shown in the figure) to quickly reduce the brake fluid pressure when the brake pedal is released during antilock control.

When the wheel brake hydraulic pressure control valve 5 is in the discharge position, the wheel brake 4 is in communication with the discharge sump 6.
The pump 7 pumps out the brake fluid in the discharge fluid reservoir 6 and sends it to the reflux point 8 in the main flow path. Further, although not shown, a combination of a buffer solution reservoir and a throttle is preferably used in order to suppress discharge pulsation of the pump 7.

The above is the basic constitution of the recirculation type anti-lock brake hydraulic pressure control device, and the following various elements are added in order to make this function also as traction control. A replenishment passage 11 is provided to connect the intermediate liquid reservoir 12 with a branch point disposed upstream of the main flow passage 3 with respect to the reflux point 8, and further between the replenishment passage 11 and the discharge liquid reservoir 6 and the intermediate liquid reservoir 12. A second switching valve 13 is provided. In addition, the intermediate liquid reservoir 12 and the main flow path 3
A relief valve 15 is provided in the communication flow path 14 therethrough, and a traction control switching valve 16 including a shutoff valve is provided between the return point 8 and the branch point.

As shown in FIG. 4, the intermediate liquid reservoir 12 has a piston 20 and a spring 21 inside, and an upper portion communicates with the communication flow passage 14 and a lower portion communicates with the atmosphere. When the atmospheric pressure is lower than the atmospheric pressure, the atmospheric pressure applied to the lower portion of the piston 20 causes the piston 20 to compress and raise the spring 21, thereby reducing the volume of the upper liquid reservoir.

In the above embodiment, the wheel brake hydraulic pressure control valve 5
3 ports for pressurizing, holding and depressurizing, 3 position solenoid type switching valve, 2nd switching valve 13 3 port 2 position pressure type switching valve, traction control switching valve 1
An electromagnetic switching valve is used as 6.

Although not shown, a signal from a rotation speed sensor for detecting the rotation speed of the wheel is received to control the control valve 5, the changeover valve 16 and the pump 7, which are electromagnetic switching valves. An electronic control unit is provided.

In the above embodiment, during normal braking, as shown in FIG. 1, the discharge valve of the wheel brake hydraulic pressure control valve 5 shuts off the main flow path 3 from the discharge liquid reservoir 6 and communicates with the wheel brake 4. During operation of the normal brake and the anti-lock brake, the second switching valve 13 is connected to the replenishment passage 11 as shown in FIG.
And the intermediate liquid reservoir 12 communicate with each other.

When the traction control is carried out, the traction control switching valve 16 operates to shut off the main flow path 3 between the connection points of the replenishing flow path 11 and the communication flow path 14, and the second switching valve 13 triggered by the master cylinder pressure.
Is the replenishment flow path 1 at the normal position where the spring biases
1 is cut off from the intermediate liquid reservoir 12, and the intermediate liquid reservoir 12 and the discharge liquid reservoir 6 are communicated with each other. Therefore, the pump 7 sucks the liquid only in the intermediate liquid reservoir 12 and the discharge liquid reservoir 6,
There is no possibility of sucking the liquid from the reservoir of the master cylinder 1.

In the second embodiment shown in FIG. 2, an electromagnetic switching valve is used as the second switching valve 13 and a pressure-responsive valve type switching valve is used as the traction control switching valve 16. Since the configuration and operation of the other parts are the same as those of the first embodiment, the same reference numerals are given and description thereof will be omitted.

A third embodiment of FIG. 3 shows a case where the present invention is applied to a two-position control ABS. The traction control switching valve 16 is a 3-port 2-position electromagnetic switching valve, and the second switching valve 13 is a master cylinder. A pressure-responsive switching valve that uses pressure as a trigger is used. In this case, the 3-port 2-position traction control switching valve 16 is connected so as to connect the master cylinder 1 and the wheel brakes 4 during the traction control, and when the sudden braking is applied during the traction control, the sudden control is performed. Pressurization is possible.

Incidentally, FIG. 3 (I) shows the state of FIG.
(II) shows when traction control is performed.

5 and 6 show an example (embodiments 4 and 5) in which the relief valve 15 is a two-position switching electromagnetic relief valve.

With the relief valve having the above-mentioned structure, immediately after the traction control is completed and the traction control is completed, the brake fluid equivalent to the set pressure of the relief valve 15 cannot return to the intermediate reservoir. It occurs, and the brake fluid is filled in the intermediate fluid reservoir only after the normal brake operation.

Therefore, if the traction control is once ended and then repeated again, and the normal brake operation is not performed during that time, during the second and subsequent traction control operations, the brake fluid to be sucked by the pump 7 in the intermediate fluid reservoir 12 is The state where there is not enough appears. That is, rather than the brake fluid capacity obtained from the hydraulic rigidity of the brake system of the vehicle and the desired traction control hydraulic pressure,
The capacity of the brake fluid existing in the intermediate fluid reservoir 12 is insufficient,
At the time of the second and subsequent traction controls, there is a risk that a satisfactory brake pressurization cannot be obtained.

Therefore, in the brake device of FIG. 5, the relief valve 15 is a two-position switching electromagnetic relief valve having a relief valve position and a fully open position of the flow passage where the flow passage resistance is 0 or close to 0, This valve is configured to take a relief valve position when the traction control is performed and to take a fully open position of the flow path when the master cylinder is pressurized. In the apparatus of FIG. 5, the control is performed so that the relief valve 15 takes the fully opened position of the flow path when the power is not supplied, so that the power is supplied only when the traction control is performed. At this time, it is desirable to switch to the relief valve position at the start of traction control from the viewpoint of ensuring the reliability of the normal brake.

On the other hand, the brake device of FIG. 6 has a two-position switching electromagnetic relief valve 1 which takes the relief valve position when not energized.
Since 5 is adopted, the relief valve position is set not only during traction control but also during normal braking, and the full open position of the flow path is set for a certain period of time immediately after the end of traction control. The time to take the fully open position of the flow path is not particularly limited to a certain time, but it is meaningless to keep the fully open position of the flow path even after the liquid to be returned to the intermediate liquid reservoir 12 is exhausted. . Power is lost because the solenoid valve is wasted.

When the traction control is restarted when the relief valve 15 is in the fully open position of the flow path in the configuration of FIG. 6, the valve 15 is naturally switched at that time to change the relief valve position. Let it take.

With this arrangement, after the traction control is completed, the main flow path 3 and the intermediate liquid reservoir 12 communicate with each other immediately so that the intermediate liquid reservoir 12 is filled with the brake fluid, so that the pump may be brake fluid after the second traction control. It becomes possible to inhale, and traction control is performed smoothly.

[0039]

[Effect] According to the present invention, since the intermediate liquid reservoir is provided in the replenishing flow path and the above-mentioned volume expansion type is adopted as the intermediate liquid reservoir, the suction resistance at the master cylinder suction port,
The effect of piping resistance from the master cylinder to the brake fluid pressure control device is avoided, and the replenishment capacity to the pump is increased,
Even if the control device is simplified, there is no delay in the rise of the brake fluid pressure at the initial stage of traction control.

On the other hand, on the other hand, when the traction control takes a long time, the intermediate liquid reservoir tries to return to the volume expansion side by the action of the intermediate liquid reservoir via the replenishing flow path even during the traction control. If the driver brakes while the brake fluid is being sucked from the reservoir, the brake circuit will have more brake fluid than the amount of brake fluid that is sent to the brake circuit according to the amount of brake pedal entry during normal brake operation. When the brake is released, the master cylinder may malfunction when the brake is released. In the present invention, the second switching valve added together with the intermediate liquid reservoir completely shuts off the gap between the pump suction port and the replenishment passage during traction control. The situation in which brake fluid is sucked into the brake circuit is avoided, which eliminates the risk of damaging the master cylinder.

The valve that uses the two-position switching electromagnetic relief valve described in FIGS. 5 and 6 as a valve for relieving the fluid in the connecting passage to the intermediate liquid reservoir quickly brakes the intermediate liquid reservoir at the end of traction control. Since the fluid is filled, there is sufficient brake fluid to be sucked by the pump in the intermediate fluid reservoir even when continuous traction control is required, which enables the desired traction pressurization and traction control. Improves reliability.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a first embodiment.

FIG. 2 is a circuit diagram of a second embodiment.

FIG. 3 is a circuit diagram of a third embodiment.

FIG. 4 is an enlarged vertical sectional view showing an embodiment of an intermediate liquid reservoir.

FIG. 5 is a circuit diagram of a fourth embodiment.

FIG. 6 is a circuit diagram of a fifth embodiment.

[Explanation of symbols]

 1 Master Cylinder 3 Main Channel 4 Wheel Brake 5 Wheel Brake Fluid Pressure Control Valve 6 Exhaust Fluid Reservoir 7 Pump 8 Reflux Point 11 Replenishment Channel 12 Intermediate Fluid Reservoir 13 Second Switching Valve 14 Communication Channel 15 Relief Valve 16 Traction Control Switching valve

Claims (12)

[Claims] 1. A wheel brake hydraulic pressure control valve including at least a discharge valve, which is provided in a main flow path from a master cylinder to a wheel brake, and a discharge liquid which temporarily stores the brake liquid discharged from the discharge valve. It has a sump, a pump that pumps up the brake fluid in the discharge sump and recirculates it to the reflux point in the main flow path, and a traction control switching valve that blocks the fluid flow from the reflux point to the master cylinder during traction control. In the brake fluid pressure control device, a replenishing flow passage branched from the main flow passage is provided upstream of the traction control switching valve, and an intermediate liquid reservoir communicating with the main flow passage is added on the replenishing flow passage at least during normal braking, A branch from the main flow path downstream of the traction control switching valve to the intermediate liquid reservoir. A flow path is provided, and a relief valve is provided in the middle of the communication flow path to relieve the liquid in the intermediate liquid reservoir when the hydraulic pressure in the communication flow path becomes higher than the maximum hydraulic pressure required for traction control. A brake fluid which is provided with a second switching valve for blocking the liquid flow from the replenishing flow path to the intermediate liquid reservoir during the traction control and connecting the intermediate liquid reservoir and the discharge liquid reservoir. Pressure control device. 2. The second switching valve is configured to communicate the replenishment flow path with the intermediate liquid reservoir during normal brake and anti-lock brake operation.
The described brake fluid pressure control device. 3. When the internal liquid pressure of the intermediate liquid reservoir becomes equal to or lower than the atmospheric pressure, the internal liquid pressure is reduced to a value close to the atmospheric pressure by reducing the volume of the liquid reservoir due to the pressure difference between the inside and the outside. Keep
When the volume of the intermediate liquid reservoir is smaller than the initial position and the flow passage from the replenishment flow passage to the intermediate liquid reservoir is in communication and the hydraulic pressure from the master cylinder reservoir acts as internal hydraulic pressure, the elastic restoring force The brake fluid pressure control device according to claim 1 or 2, wherein the volume of the intermediate fluid reservoir is increased. 4. The brake fluid pressure control device according to claim 1, wherein the second switching valve is a pressure-responsive switching valve triggered by a master cylinder pressure. 5. The brake fluid pressure control device according to claim 1, wherein the traction control switching valve is a pressure responsive switching valve triggered by a master cylinder pressure. 6. A traction control switching valve is provided downstream of a branch point between a main flow path and a supply flow path, and as the traction control switching valve, communication with a master cylinder is provided either at a return point from a pump or a wheel cylinder. The brake fluid pressure control device according to claim 1, 2 or 3, characterized in that a 3-port 2-position valve that switches to (4) is used. 7. The two-position switching valve, wherein the relief valve is configured as a relief valve position when traction control is performed and a fully open position of a flow path when a master cylinder is pressurized. The brake fluid pressure control device according to any one of 1. 8. The brake fluid pressure control device according to claim 7, wherein an electromagnetic valve is used as the relief valve for switching the two positions. 9. The brake fluid pressure control device according to claim 8, wherein the electromagnetic relief valve for switching between the two positions is one that takes a fully opened position of the flow path when not energized. 10. The brake fluid pressure control device according to claim 9, wherein the two-position switching electromagnetic relief valve is configured to switch to the relief valve position at the start of traction control. 11. The brake fluid pressure control device according to claim 8, wherein the two-position switching electromagnetic relief valve is one that takes a relief valve position when not energized. 12. The relief valve is a two-position switching electromagnetic relief valve that takes the relief valve position when not energized and takes the fully open position of the passage when energized, and fully opens the passage only for a certain period of time immediately after the end of traction control. The brake fluid pressure control device according to any one of claims 1 to 6, which is configured to take a position.