JPH0218147A - Brake gear with anti-lock controller for automobile - Google Patents

Abstract

PURPOSE: To reduce cost by simplifying structure by arranging a modulation device to function a main brake piston as a modulation piston in a main brake cylinder having two brake chambers to which each of brake circuits is connected. CONSTITUTION: A main brake cylinder 16 having two brake chambers 14, 15 to which each of brake circuits I, II is connected is constituted by fitting two brake pistons 21, 22 inside of which filling valves 23, 24 are incorporated by arranging them longitudinally. In this case, a modulation chamber 31 of a modulation device 32 for brake pressure adjustment of anti-lock control is made by restricting a cylinder section by an end surface 211 of the first piston 21 out of the pistons 21, 22 and a cylinder end surface 161, and the same chamber 31 is made free to be connected to a tank 13 through a change-over valve 33 or to a pressure accumulator 10 through a change-over valve 34 respectively. Additionally, a power piston 35 is connected to the piston 21 free to transmit power.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a brake device equipped with an anti-lock control device for an automobile, which has a main brake cylinder,
At least one main brake piston for introducing brake pressure into at least one brake circuit in the main brake cylinder is guided in an axially displaceable manner and can be driven as a pressure modulator for an anti-lock control device. The boosting device includes a boosting cylinder and a boosting piston that is movable within the boosting cylinder and can be controlled by operating a brake pedal using a brake valve. is adapted to act mechanically on the main brake piston, and has an additional modulation device independent of the pressure modulator for effecting brake pressure modulation, the modulation device being connected to the modulation piston and by means of this modulation piston. The invention relates to a type with a limited modulation chamber, which is alternately connected via a valve arrangement to a pressure source or to a pressure relief point.

The pressure modulation occurring in the booster, which operates as a pressure modulator during anti-lock control, has a negative effect on the brake pedal due to the connection between the booster piston and the brake pedal and is clearly felt by the driver operating the brake pedal. In order to reduce the adverse effects on the pedals, an additional modulation device for pressure modulation is provided independently of the booster/pressure modulator. For average modulation widths, i.e. the magnitude of pressure fluctuations, the pressure modulation is carried out exclusively by the modulation device, whereas the booster piston cannot move its instantaneous axial position in the direction in which the pressure is created. is fixed. On the other hand, with large modulation widths, both the booster and the pressure modulator for the brake pressure come into play.

The known brake system of the type mentioned at the beginning (DE-OS
No. 3,612,793), the booster piston is connected to the main brake piston via a pressure rod, which itself contacts the booster piston more loosely in the axial direction. The modulation member is incorporated within the booster. For this purpose, the modulation piston is rigidly connected to the pressure rod and divides the return chamber or counterchamber, which is arranged at the end face opposite to the working chamber or pressure chamber of the booster piston, into two chamber sections; The chamber section facing the force piston forms the modulation chamber of the modulation device and is connected to the valve arrangement. In order to achieve an average modulation of the modulation width, the modulation chamber is relieved or loaded with pressure by means of a suitable control of the valve arrangement, so that the modulation piston depresses or depresses the main brake piston via a pressure rod. load. In this case, the booster piston is uncoupled by the movement of the pressure rod and maintains the axial displacement position it occupied before implementing the anti-lock control.

Another known brake device of the type mentioned at the outset (DE-O
No. 5,344,828), a modulation device is arranged within the main brake cylinder. The modulation piston here is constituted by a second booster piston, which serves to increase the brake pressure during braking, and which limits a modulation chamber that is connected to the valve arrangement.

Together with the pump piston, the booster piston forms a piston unit which is arranged axially displaceably on the main brake piston. The pump piston delimits the brake chamber together with the main brake cylinder with its end ring surface. Via the form-locking entrainment, the pump piston entrains the main brake piston during its movement in the direction of brake pressure build-up.

Whereas in the case of average pressure modulation of the modulation width, the main brake piston is locked in the instantaneous axial displacement position of the booster via the hydraulically defined booster piston, the second A piston unit consisting of a booster piston and a pump piston moves axially on the main brake piston under the control of a valve device.
Decrease or increase brake pressure in the brake chamber.

The inventive design of the brake system has the advantage that the modulation device is structurally simple and economically inexpensive. The split modulation piston and the two-part structure of the boost piston and the pressure rod in the boost cylinder are eliminated. Taking into account sealing problems a relatively expensive piston construction of pistons arranged coaxially and movably relative to each other is avoided. For a main brake piston for a brake system that operates without an additional modulation device, it is only necessary that the main brake piston be designed so that it can be loaded with pressure on the rear side facing away from the brake chamber.

Advantageous developments of the invention are described in the following claims.

The hydraulic brake device shown in the drawings is supplied with pressure from a pressure accumulator 10, and the pressure accumulator is maintained at a predetermined pressure using a hydraulic pump 12 driven by an electric motor 11. has been done. Instead of an electric motor, a liquid capon 12 is supplied from a drive present in the vehicle, for example a vehicle engine.
The drive torque for is extracted and the transmission, e.g. V
Transmitted via a belt transmission.

Pressure medium, here brake fluid, is sucked in from the tank 13 by the liquid pump 12, and the brake fluid is returned to the tank via the return conduit. The brake system has two brake circuits I and (2) separated from each other, each brake circuit being connected to a separate brake chamber 14.15 of the main brake cylinder 16. Brake circuit l
supplies brake pressure to the right front wheel VR and the left rear wheel HL, while the brake circuit (2) supplies brake pressure to the left front wheel VL and the right rear wheel HR. A brake pressure holding valve 17 is provided in a known manner in the brake line leading to the wheel brake cylinder of the front or rear wheel.
~20 are connected.

Inside the main brake cylinder 16, two main brake pistons 21, 22, each incorporating a filling valve 2324, are arranged one behind the other and are movable in the axial direction. Each main brake piston 2122 delimits a brake chamber 14 or 15, respectively, which is filled with pressure medium via a filling valve 23 or 24 from a filling container 25, which fills into the tank 13. It is connected. After moving the main brake pistons 21.22 relative to each other through a predetermined travel distance, the filling valve 23.24 is closed;
The connection to the filling container 25 is cut off. Each main brake piston 21 , 22 is loaded by a return spring 26 or 27 , which rests on a stationary stop 28 or 29 in the housing and pushes the associated main brake piston 21 or 22 into its reference position. There is. The second main brake piston 22 is brought into abutment by a return spring 27 against a stop 28 of a return spring 26 that loads the first main brake piston 21 and limits the first brake chamber 14 with an end face 221. 1st
The main brake piston 21 of
0, in which case the end face 211 of the main brake piston 21 and the end wall 161 of the main brake cylinder 16 delimit a cylinder section, which cylinder section is used for modulation of the brake pressure in anti-lock control. It forms a modulation chamber 31 of the device 32. The modulation chamber 31 can be connected to the tank 13 via a first switching valve 33 and to the pressure accumulator 10 via a second switching valve 34 . The two switching valves 33, 34 are designed as two-position solenoid valves, with the first switching valve 33 being open and the second switching valve 34 being closed in the non-energized reference position. An axially movable push rod 30 that penetrates the end wall 161 of the main brake cylinder 16 in a fluid-tight manner is rigidly connected to a boost piston 35 of a booster 36, which booster is connected to the main brake cylinder 16. composed together. The booster piston 35 is axially displaceably guided in a booster cylinder 37, which is connected axially to the main brake cylinder 16. In the illustrated reference position, the booster piston 35 is brought into abutment by the main brake piston 21 and the push rod 30 against a stopper 38 that is immovable in the casing.

The booster piston 35 delimits a pressure or working chamber 39 by an end face 351 on the right in the drawing and a counter or return chamber 40 by an end face 352 on the left in the drawing. A brake valve 41 is incorporated within the booster piston 35, the brake damping of which is mechanically controlled by a brake pedal 42. The brake valve 41 has a control spool 44 which is provided with different control holes and which is connected via a pedal rod 43 to the brake pedal 42 and which is adapted to the adjusting movement of the brake pedal 42 by means of a soft return spring 45. being loaded against it.

The structure and operation of the brake valve 41 are known and are described in detail, for example, in DE-So 3444828.

The booster 36 acts as a pressure modulator during anti-lock control and for this purpose the booster return chamber 4
0 is connected to or shut off to the tank 13 or to the outlet 52 of the working chamber 39 via a valve unit consisting of three switching valves 46, 47, 48. Each switching valve 46.47.4
Reference numeral 8 is configured as a 2-point, 2-position solenoid valve. Both switching valves 46 and 47 are open in their non-energized normal position, whereas switching valve 48 is closed in its normal position, and switching valve 46 is provided with a throttle. The working connection of the switching valve 34 is not connected directly to the pressure accumulator 10, but to the outlet 52 of the working chamber 39 of the booster 36 and indirectly connected to the pressure accumulator 10 via this working chamber. has been done.

The operating mode of the exemplary brake system is as follows: In the reference position of the brake pedal 42, the return spring 45 is active and the control spool 44 occupies the reference position. The working chamber 39 of the booster 36 is connected via a control hole of the control spool 44 and an outlet hole 49 of the booster cylinder 37 to a return conduit (shown in broken lines in the drawing) opening into the tank 13 . Actuation of the brake pedal 42 first moves the control gear 44 via the pedal rod 43, so that the connection of the working chamber 39 to the outlet hole 49 is interrupted and the connection of the working chamber 49 to the inlet 50 is effected; The inlet is connected to the pressure accumulator 10 via a supply conduit. Pressure medium now flows into the working chamber 39 from the pressure accumulator 10 .

A portion of the pressure medium flows via the check valve 51 to the outlet 52 of the working chamber 39, the switching valve 34 connected to the outlet being in the blocking position.

Due to the pressure created in the working chamber 39, the booster piston 3
5 is moved to the left side as seen in the drawing, in this case push rod 3
0 moves the main brake piston 21 in the same way.

The boost piston 35 is moved while the working chamber 39 is connected to the pressure accumulator 10 . The booster piston is stopped when the control spool 44, by its relative movement with respect to the booster piston 35, interrupts the connection between the working chamber and the pressure accumulator.

After a slight displacement movement, the filling valve 23 of the main brake piston 21 is closed. The brake pressure built up in the brake chamber 14 moves the main brake piston 22 of vg2 in the same direction, so that the filling valve 24 also closes and a brake pressure builds up in the second brake chamber 15 as well. Both brake pressures are introduced into both brake circuits I and ① and thus into the wheel brake cylinders of the wheels.

If the brake pedal 42 is pressed too hard, the wheel brakes will be applied too hard, resulting in undesirable wheel slip and anti-lock control system activation.

Based on the detection of wheel slip by wheel sensors (not shown), the switching valve 33.34°46.47.48
A switching signal is generated for a valve arrangement consisting of: All switching valves are switched using the first switching signal. A pressure is created in the return chamber 40, which causes the booster piston 35 to move to the right in the drawing. A pressure is likewise created in the modulation chamber 31 via the switching valve 34, which pressure is applied to the main brake (in the same direction of the stone 21,
That is, a slight movement to the right side as seen in the drawing is allowed. As a result, the force-transmissible connection between the booster piston 35 and the main brake piston 21 is released. By switching the switching valve 48, the return chamber 40 is shut off and the booster piston 35 is locked in its instantaneous displacement position by the same pressure in the working chamber 39 and in the return chamber 40. Wheel slip is compensated by the pressure camoshage controller, which controls the modulation chamber 3 by switching the switching valves 33 and 34 simultaneously.
It will be canceled within 1. This allows modulation chamber 3
The pressure inside the booster piston 35 and the brake pedal 42
The braking pressure controlled by the brake pedal 42 is reduced and increased impulsively in the stationary state, so that the brake pressure controlled by the brake pedal 42 provides slip-free braking.

By means of the brake pressure holding valves 17, 18, 19, 20, only the wheel brake cylinders belonging to the wheel causing the slip are instantaneously connected to the brake chamber 14, 75 during antilock control. The remaining wheel brake cylinders are isolated from the brake chamber 14, 15 during antilock control by the brake pressure holding valve which is switched to the pressure holding position. If the brake pressure drop produced by the modulation device 32 is not sufficient, the booster 36 is brought into play as a pressure modulator.

In this case, the switching valve 48 again assumes the pressure overflow position, thereby creating an increasing return force in the return chamber 40 of the booster piston 35, which returns pressure moves the booster piston 35 in the direction of decreasing braking force. , that is, move it to the right side as seen in the drawing. In the same way, the push rod 30 is returned, which causes the main brake piston 21 .
22 full movements are possible.

Claims (1)

[Scope of Claims] 1. A braking device equipped with an anti-lock control device for an automobile, which has a main brake cylinder, and for introducing brake pressure into at least one brake circuit in the main brake cylinder. at least one main brake piston of the main brake piston is guided in an axially movable manner and has a booster which can be driven as a pressure modulator for the anti-lock control device, the booster being connected to a booster cylinder and this booster. It is equipped with a booster piston that is movable within the force cylinder and can be controlled by operating the brake pedal using a brake valve.The booster piston mechanically acts on the main brake piston, and the brake pressure is It has an additional modulation device independent of the pressure modulator for carrying out the modulation, the modulation device comprising a modulation piston and a modulation chamber delimited by the modulation piston, the modulation chamber being connected via a valve device. In the version which is intended to be connected alternately to a pressure source or pressure relief point, a modulation device (32) is arranged in the main brake cylinder (16) and the main brake piston (21) is connected directly to the main brake piston (21). It forms a modulation piston, and one end face (
211) restricts the cylinder section of the main brake cylinder (16) as a modulation chamber (31), and the main brake piston (21) and booster piston (35)
A brake device 2 equipped with an anti-lock control device for an automobile, characterized in that the valve devices are connected to each other in a direction of movement so as to be able to transmit force, the valve device having two switching valves (33, 34), A first of the switching valves is closed in an energized working position and a second switching valve is closed in an unenergized reference position, and one valve connection of the switching valves (33, 34) is closed. The modulation chamber (
31) and is connected to the cylinder section forming the first
The other valve connection part of the switching valve (33) is the pressure relief point (13)
2. Brake device according to claim 1, characterized in that the second switching valve (34) is connected to the pressure source (10) and that the other valve connection of the second switching valve (34) is connected to the pressure source (10). 3. The booster piston (35) has a push rod (30) that extends axially into the main brake cylinder (16), and the main brake piston (21) presses the push rod under the action of a compression spring (26). The brake device according to claim 1 or 2, wherein the brake device is in contact with the end portion of (30). 4. The booster piston (35) separates the booster cylinder (37) into a working chamber (39) and a return chamber (40) that can be controlled by the brake valve (41), and the return chamber is connected to the valve unit (46). , 47, 48) selectively using the working chamber (39)
4. The brake device according to claim 1, wherein the brake device can be connected to or disconnected from the pressure relief point (13). 5. A brake valve (41) is integrated into the booster piston (35) and is installed in the brake for selective connection of the working chamber (39) with the pressure source (10) or the pressure relief point (49, 13). 2. Brake device according to claim 1, wherein the brake device is connected to a pedal (42). 6. According to any one of claims 2 to 5, wherein the second switching valve (34) and the pressure source (10) are connected through a working chamber (39) of the booster (36). brake equipment.