JPH04212664A - Fluid pressure brake system - Google Patents

Abstract

PURPOSE: To provide a hydraulic brake system having less possibility of failure and of favorable ventilation by inserting a hydraulic pump into a brake conduit to communicate the suction side with a master brake cylinder, and the pressure side with a wheel brake cylinder. CONSTITUTION: A hydraulic pump 4 is inserted into a brake conduit 2 to communicate the suction side S with a maser brake cylinder 1, and the pressure side D with a wheel brake cylinder. An suction valve is provided between the pump 4 in the brake conduit 2 and the wheel brake cylinder, the suction valve 7 opens the brake conduit 6 at a constant position, and it disconnects it at a changed over position. A wheel brake 3 is communicated with a pressure fluid collector device 10 through a return conduit 9, a delivery valve 8 is inserted into the return conduit 9, the delivery valve 10 disconnects the return conduit 9 at a constant position, and it opens it at a changed over position.

Description

[Detailed description of the invention]

0001

TECHNICAL FIELD The present invention relates to a hydraulic brake system, in which at least one wheel brake communicates with a master cylinder through a brake conduit, and when a pedal is actuated, pressure fluid is transferred from the master brake cylinder through the brake conduit. The present invention relates to a hydraulic brake system with a brake slip/traction slip control device comprising a pedal actuated master cylinder that moves to a wheel brake cylinder and a hydraulic pump.

0002

BACKGROUND OF THE INVENTION A brake system of the above type is disclosed, for example, in DE OS 3,831,426. The pump has the function of conveying the discharged pressurized fluid from the wheel brake to the brake conduit when controlled. For this purpose, the suction side of the pump is connected to a pressure fluid collector device connectable to the wheel brake, and the pressure side of the pump is connected to the master brake cylinder. The pump is therefore arranged in a branch of the brake conduit, so that no pressure fluid can escape there during uncontrolled deceleration. The connection between the suction side and the master brake cylinder is made only during traction slip control. In this case, the pump absorbs pressure from a reservoir connected to the master brake cylinder and sends this pressure to the wheel brakes. However, pressure is sent in this way only when the master brake cylinder is not operating, that is, when it is in a non-pressurized state.

There are essentially two disadvantages to circuits of the above type. First, in brake slip control, the pump discharges fluid from the non-pressurized pressure fluid collection device using the pressure of the master cylinder. Therefore, when the brake fluid is cold and viscous, the control quality is degraded because the pump will not reach its maximum output unless the starting phase is extended. Another disadvantage is that automatic suction pumps create a vacuum in the absence of suitable pressure fluid on their suction side. Air tends to enter this vacuum section if the corresponding seal is broken. Since the pump is located in a branch of the brake conduit, it is difficult to remove the incoming air, and cavities within the brake system are susceptible to failure of the brake system.

0004

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a hydraulic brake system that permanently guarantees a high degree of control regardless of the ambient temperature, has a low possibility of failure, and is particularly easy to ventilate. It is in.

[0005]

The object of the invention is achieved by the means according to claim 1, in which at least one wheel brake (3) is connected via a brake conduit (2) to a master brake cylinder (1). and comprises a pedal actuation master cylinder (1) through which pressurized fluid moves from the master brake cylinder through the brake conduit into the wheel brake when the pedal is actuated, and a fluid pressure pump (4), the pump comprising: solved by a hydraulic brake system inserted into said brake conduit (2) such that its suction side S communicates with said master brake cylinder (1) and its pressure side D communicates with said wheel brake cylinder. .

[0006]

[Operation] In the above configuration, the brake conduit is equipped with a pump, so when the pump starts, there is a pressure equilibrium between the suction side and the pressure side of the pump, and the function of the pump is significantly improved, especially at low temperatures. Air pockets that are unavoidable during the deceleration process are removed from the pump and the efficiency of the pump is maintained.

[0007] Brake pressure regulators typically consist of a suction valve and a discharge valve that control the supply of pressurized fluid to the wheel brakes. These valves are electromagnetically actuated and control signals by an electronic analyzer are available to evaluate the sensor signals that determine the rotation pattern of the wheels.

The valve separating the master cylinder from the suction side of the pump is isolated from the brake circuit when brake slip control is performed, so that pressure fluctuations within the system have no effect on the master cylinder.

The high-pressure accumulator on the pump pressure side absorbs the pressure fluid delivered by the pump and acts as a pressure generator instead of the master cylinder. In order to prevent pressure fluid from absorbing pressure fluid prematurely during the normal deceleration process,
The accumulator spring is biased to prevent the accumulator from absorbing pressure fluid at pressures that would prevent the wheels from locking.

The direct conduit is equipped with a check valve between the wheel brake and the master cylinder, which prevents the pressure in the wheel brake from becoming higher than the pressure in the master cylinder. As a result, the driver does not need to perform controlled deceleration by increasing or decreasing the pressure applied to the pedal. Also, the pressure reduction during uncontrolled deceleration takes place directly via the conduit.

In order to generate pressure on the wheel brakes even without pedal activation, as required for traction slip control, the direct conduit is equipped with an electromagnetically actuated valve that shuts off the direct conduit during traction slip control. do.

A release valve between the suction side and the pressure side of the pump prevents the pressure on the pressure side of the pump from increasing too much.

It is also desirable that the brake conduit isolation valve be mechanically actuable. In this case it is advantageous to mechanically couple the separating valve and the accumulator so that the separating valve closes when the piston of the accumulator moves.

[0014] The release valve can also operate within the accumulator;
For this purpose, the piston of the accumulator is equipped with a valve. This valve is forced open by the force of a spring via a plunger when the piston of the accumulator moves a predetermined distance. Pressure fluid in the chamber of the accumulator can flow via a connecting conduit into a backpressure chamber that communicates with the suction side of the pump. The energy demand when loading the accumulator is therefore reduced. Similarly, an additional amount of pressurized fluid corresponding to the volume of the backpressure chamber can be kept at high pressure, so that even if the pump fails during the control process, the pump will continue to operate.

Controllable throttles communicating with the suction and pressure sides of the pump can also positively influence the efficiency of the pump.

Another advantage possible with this system is that it provides a boosting effect. To obtain this effect, the pump must be controlled proportionally to the pedal force.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The principle of the present invention, its development and application will be explained in detail with reference to four drawings.

First, FIG. 1, which represents the basic principle of the present invention, will be explained. The brake system comprises a master brake cylinder to which one or more wheel brakes 3 are connected via brake conduits 2 . A pump 4, which will be explained in more detail below, is installed in the brake conduit, the suction side S of which communicates with the master brake cylinder 1 via a first brake conduit 5, and the pressure side D communicated with the master brake cylinder 1 via a second brake conduit 6. Communicates with the wheel brake. The second brake conduit 6 is equipped with an electromagnetically operated suction valve. The valve opens the conduit in the home position and blocks the conduit in the switched position. The wheel brake 3 communicates with a pressure fluid collector device 10 via a return conduit 9, which is equipped with a discharge valve 8. This discharge valve 8
is also electromagnetically operated, but in the home position it blocks the return conduit and in the switched position it opens the return conduit. The pressure fluid collector device 10 is a low pressure accumulator with limited capacity. This device communicates via a check valve 11 with the first brake conduit 5 section (discharge point E). A separation valve 12 is provided between the discharge point E and the master brake cylinder 1. The valve 12 is actuated electromagnetically in this embodiment and keeps the brake line open in the home position and shuts it off in the switched position.

The wheel brake 3 communicates with the master brake cylinder 1 via a direct conduit 13;
is equipped with a check valve 14 that opens toward the master brake cylinder. This direct conduit is further equipped with a shutoff valve 15. Due to its function, this valve is hereinafter referred to as the ASR valve, but in its normal position, it continues to directly open the conduit.
In the switching position for traction slip control, the direct line is shut off. The pressure side D of the pump communicates with a high pressure accumulator 16 . This accumulator is a piston-type accumulator in this embodiment. The accumulator piston 17 is loaded with a strong spring so that the volume of the accumulator chamber is minimized. The spring-type accumulator 18 is prestressed so that the pressure on the pressure side D of the pump is at a minimum and the accumulator absorbs the volume.

The pump 4 based on this embodiment is a piston type pump, and the pump piston 19 is moved by an electric eccentric plate 20. A pump chamber 21 at the end of the pump piston 19 communicates with the suction side S and the pressure side D of the pump 4 via one check valve 22 and 23, respectively. Check valve 2
2 is open toward the pump chamber, and the check valve 23 is closed toward the pump chamber. The discharge valve 24 communicates with the pressure and suction sides of the pump and prevents the pressure accumulator 16 from being overloaded.

The illustrated braking system operates in the following pattern.

1. When the uncontrolled reduction pedal is actuated, pressure fluid moves from the master brake cylinder 1 into the wheel brake 3. The pressure path includes the open separation valve 12, the first check valve 22, and the pump chamber 2.
1, the second check valve 23, and the open suction valve 7. Pressure is created in the wheel brake 3, resulting in a deceleration of the wheels and a deceleration of the vehicle. When the pedal is released, pressure fluid returns from the wheel brake 3 to the master brake cylinder via the open check valve 14, the direct conduit 13 and the open ASR valve. It is important that the pressure generation path continues up to the pump chamber 21 during normal deceleration.

2. Brake slip control The brake operation pattern of the wheels being decelerated is constantly monitored by a sensor (not shown). The electronic analyzer can therefore detect as soon as the wheels are about to lock up. When the wheels lock, the analyzer begins the following steps.

First, the intake valve 7 is switched over to shut off the brake line. The discharge valve 8 opens, so that pressure fluid flows from the wheel brake into the low-pressure accumulator 10. Valve 12 closes, disconnecting the master brake cylinder from the brake circuit. Pump drive M is activated and the pump delivers pressurized fluid from low pressure accumulator 10 to high pressure accumulator 16 . Since the piston 17 moves against the force of the spring 18, the pressure at the outlet of the pump D corresponds to the force of the spring. Inlet valve 7 and outlet valve 8 are switched in sequence so that pressure fluid is supplied to and discharged from the wheel brake. This is done according to a certain algorithm, so that it is possible to optimally adjust the value of the wheel slip. The pressure in the wheel brake is limited via the direct line 13 to the extent of the pressure in the master brake cylinder. When the driver's pedal pressure decreases, the pressure in the wheel brake also decreases and the deceleration or control process is respectively terminated.

3. When the traction slip control wheel is a drive wheel, the torque transmitted by the vehicle's engine exceeds the torque that can be transmitted between the tires and the road, potentially resulting in wheel spin. To prevent such wheel spin, the braking system should correct the drive torque so that the remaining torque matches the force that can be transmitted between the tires and the road by the brake torque. The aforementioned sensors can also detect a tendency to slip. The electronic analyzer initiates the next stage. The pump motor is activated and the pump directs pressurized fluid from the reservoir corresponding to the master brake cylinder through the master brake cylinder and the open isolation valve to the wheel brake. The ASR valve 15 is closed and the pressure fluid sent to the wheel brakes cannot flow back from the direct conduit to the master brake cylinder. As in the case of brake slip control, an optimum brake pressure can be set in the wheel brake by switching valves 7 and 8. In such brake systems, the pump must be of the self-absorbing type, since there is no static pressure on the suction side of the pump, as in the case of traction slip control. The release valve 24 prevents overpressure from being created on the pressure side of the pump.

Next, an embodiment based on FIG. 2 will be described.

The embodiment according to FIG. 2 is essentially the same as the embodiment according to FIG. However, unlike FIG. 1, the separation valve is not electromagnetically operated, but is mechanically operated depending on the filling level of the high pressure accumulator 16.

Piston 17 and valve 12 are therefore arranged in a common housing. Accumulator piston 1
7 is an extension 3 whose end faces towards the accumulator chamber and which has a smaller diameter than the accumulator piston 17;
0. This extension 30 is sealed and guided into the bore, and at the end opposite the accumulator piston is
There is a plunger 31 that can pass through a bore 32. This bore connects a suction chamber 36 and a discharge chamber 37, the suction chamber 36 communicating with the master brake cylinder and the discharge chamber 37 communicating with the pressure side of the pump. The discharge chamber 37 is delimited by the front surface of the extension 30 . The isolation valve consists of a ball valve 34 in the intake chamber 36 and a valve seat 33 on the bore 32. The valve spring 35 pushes the ball valve towards the valve seat 33. When the piston 17 is in the home position, i.e. in the position where the volume of the accumulator chamber is at a minimum, the plunger 31 passes through the bore 32;
The ball valve 34 is separated from the valve seat 33.

Pressure fluid flows freely from the master brake cylinder 1 to the pump. During brake slip or traction slip control, the accumulator is filled as described above and the illustrated accumulator piston 17
moves to the right as soon as a suitable pressure is created on the pressure side of the pump. The plunger 31 is pulled out from the bore 32,
The ball valve 36 is seated in the valve seat 33 and the brake conduit is shut off. The other operations in the brake system are the same as the operation of the brake system based on FIG. FIG. 3 shows another embodiment of the brake system according to FIG. 1, but importantly, the release valve is in the accumulator. For this purpose, the accumulator piston 17 is connected to the valve 4
3. This accumulator piston 17 separates the chamber 40 from the backpressure chamber 41. The valve 43 has a connecting bore in the piston 17 between the two chambers 40, 41, the valve member being located in the accumulator chamber 40 and can be mounted on the connecting bore. As the accumulator piston moves to the right as shown, the plunger 44 moves into the bore and the ball valve of valve 43 rises out of the bore, causing the accumulator chamber 40
Pressure fluid flows between the back pressure chamber 41 and the back pressure chamber 41 . The backpressure chamber 41 communicates with the suction side of the pump via a connecting conduit 42. When the accumulator reaches a predetermined filling level and, as a result, the pressure in the storage chamber reaches a predetermined level in response to the compression of the spring 18, the valve 4
3 is opened and the pressure fluid further enters the accumulator chamber and returns to the suction side of the pump via the back pressure chamber. The rest of the structure and function of this brake system are the same as the brake system of FIG.

FIG. 4 represents the complete braking system of a four-wheeled vehicle comprising wheels 64, 65, 66, 67,
, HL, VL, and VR each refer to the next wheel.

HR = Rear right wheel HL = Rear left wheel VL = Front left wheel VR = Front right wheel The master cylinder 1 consists of two chambers 60 and 61, each of which constitutes one brake circuit. The chamber 60 is connected to the wheels HR and HL via the brake conduit 2'.
The wheel brake is connected. The brake pressure in the two wheel brakes is typically controlled by a control system as shown in FIG. The brakes for wheels VL and VR are provided by branch circuits 62 and 62 of the brake conduit 2'', respectively.
63 to the chamber 61 of the master brake cylinder.
It communicates with The branch circuits 62 and 63 are each equipped with a control system as shown in FIG.

This brake system is therefore equipped with three control circuits, each with a pump 4', 4''.
, 4''' are equipped. It should be noted that the control system in this regard can also be placed in the positions shown in FIGS. 1 and 3.

[0033] The point I would like to particularly emphasize is that the pumps 4', 4'',
4''' is the fact that they operate with a common drive, namely the electric motor EM. Another feature is that the individual intake and discharge valves are in the form of 3-way/2-position valves 68, 69, 70. The system is therefore simple, but has the disadvantage that it is not possible to implement a pressure maintenance phase in which both the brake conduit and the return conduit are shut off.

Since each control system operates on the principle described above, it is naturally possible to adjust the pressure in the wheel brake of each control conduit individually.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a brake system that is an embodiment of the present invention.

FIG. 2 is a configuration diagram of a brake system according to another embodiment of the present invention.

FIG. 3 is a configuration diagram of a brake system according to another embodiment of the present invention.

FIG. 4 is a configuration diagram of a brake system according to another embodiment of the present invention.

[Explanation of symbols]

1...Master brake cylinder, 2...Brake conduit, 3...
Wheel brake, 4...Pump, 7...Suction valve, 8...Discharge valve, 10...Low pressure accumulator, 12...Separation valve, 15...
Shutoff valve, 16...high pressure accumulator.

Claims (16)

[Claims] 1. A brake slip/traction slip control device, wherein at least one wheel brake (3) communicates with a master brake cylinder (1) via a brake conduit (2), and when the pedal is actuated, pressurized fluid consists of a pedal actuated master cylinder (1), which moves from the master brake cylinder into the wheel brake via the brake conduit, and a hydraulic pump (4), the pump having a suction side S connected to the master brake. Hydraulic brake system, characterized in that it is inserted into said brake conduit (2) in such a way that it communicates with the cylinder (1) and its pressure side D communicates with the wheel brake cylinder. 2. A suction valve (7) is provided between the pump (4) of the brake line (6) and the wheel brake cylinder, which opens the brake line in the home position and blocks it in the switching position; The wheel brake (3) also communicates with the pressure fluid collector device (10) via the return conduit (9), and the discharge valve (8) is inserted into the return conduit (9).
Hydraulic brake system according to claim 1, characterized in that in the home position of this valve the return conduit is blocked and in the switching position the conduit is opened. 3. The pressure fluid collector device (10) connects the pump (5) of the brake conduit (5) via the check valve (11) with
4) and the master brake cylinder (1), and a separation valve (12) is connected between the release point E and the master brake cylinder (1).
3. Hydraulic brake system according to claim 2, characterized in that a valve is inserted, which opens the brake conduit in the home position and blocks it in the switching position. 4. Brake system according to claim 2, characterized in that the high-pressure accumulator (16) communicates with the pressure side D of the pump (4). 5. Brake system according to claim 4, characterized in that the accumulator (16) is filled only when the pressure side D of the pump is at a minimum pressure. 6. The wheel brake (3) is in direct communication with the master brake cylinder (1) via a direct conduit (13), a check valve (14) is inserted into the direct conduit (13), and the master brake cylinder The hydraulic brake system according to claim 2, wherein the hydraulic brake system is open in the (1) direction. [Claim 7] The shutoff valve (ASR valve 15) is directly connected to the conduit (
13), opening the conduit in the home position and blocking the conduit in the switching position. [Claim 8] The pump is a reciprocating piston type pump (
4), the pump chamber (21) communicating with the suction side S and the pressure side D via one check valve (22, 23) in each case. brake system. 9. Hydraulic brake system according to claim 1, characterized in that the suction side S and the pressure side D of the pump communicate with each other via a discharge valve (24). 10. Hydraulic brake system according to claim 3, characterized in that the isolation valve (12) is mechanically actuated by a piston (17) of the high-pressure accumulator (16). 11. The separation valve (12) is in the form of a seated valve, the valve body (34) is actuated by a plunger (31) mounted on the piston (17), and the valve (12) is connected to the accumulator (16). 11. The hydraulic brake system according to claim 10, wherein the hydraulic brake system closes upon filling of the hydraulic brake system. 12. A separating piston (17) of the high pressure accumulator (16) separates the accumulator chamber (40) from the back pressure chamber, and a valve (43) separates the separating piston (
17), and when this valve (43) is actuated by a plunger and the inside of the accumulator chamber (40) reaches a predetermined filling level, the accumulator chamber (40) and the back pressure chamber (41) communicate with each other. 6. The hydraulic brake system according to claim 5. 13. The back pressure chamber (41) is connected to the connecting conduit (
13. Hydraulic brake system according to claim 12, characterized in that it communicates with the suction side S of the pump (4) via the pump (42). [Claim 14] Suction side S and pressure side D of the pump (4)
Hydraulic brake system according to claim 1, characterized in that a controllable throttle is connected between the pumps, the cross section of which is determined by the pressure difference between the suction side S and the pressure side D of the pump. 15. A triple circuit system is provided for a four-wheeled vehicle, in which a rear axle wheel brake and a front axle wheel brake constitute one circuit, and each control circuit is equipped with a pump ( 4′, 4″, 4
15. Hydraulic brake system according to claim 1, characterized in that a common drive device is provided for the hydraulic brake systems ``''). 16. The above-mentioned claim 1, wherein the intake valve (7) and the discharge valve (8) are in the form of a 3-way/2-position valve.
16. The hydraulic brake system according to any one of items 1 to 15.