DE2118644C3 - Pressure medium-actuated and anti-lock vehicle brake system - Google Patents

Description

The invention relates to a pressure medium-actuated and anti-lock vehicle brake system of the type specified in claim 1.

Such a vehicle brake system is known from CH-PS 458092. If the brake pressure at Occurrence of the first rotation delay signal should be reduced slowly and should be reduced quickly when the second rotation delay signal occurs, one finds System use that has an inlet valve and two outlet valves, of which the two outlet valves have different cross-sections for the outflow of the brake air. The different Valves can also be assembled in one unit. Nevertheless, the individual parts are two Complete exhaust valves are required to achieve a total of two different Druckabsenkungsgeschwindigkcitcn

DE-AS 1 IbM) 12 shows a similar Fahrzcugbremsanlage, but with only one outlet valve Is used, which is followed by a throttle valve, which is either a throttled or but releases the full cross-section. Here, too, two valves are required to achieve two different Druckabscnkgeschwindigkitcn. Hk-DR-DS I W2 I.W shows the use of a proportional in a similar vehicle brake system controllable inlet valve. This makes it possible to vary the brake pressure increase in each case according to the proportional control by the To achieve inlet valve.

The invention is based on the object of structurally simplifying the system of the type described and still the advantageous mode of action, namely different pressure reduction speeds <oi

ίο enable.

According to the invention this is achieved in that the outlet valve contains a leak, and that the first Rotation delay signal a signal proportional to the control pressure is superimposed, and thus the The flow cross-section of the leak changes continuously in relation to the received signal. So that we Depressurization speed at the occurrence of the first rotation delay signal depending on the level of the included control pressure differently

2 (i fall, with an ongoing adjustment accordingly the changing control pressure takes place. Only when the second rotation delay signal occurs will that Exhaust valve fully open. This results in the advantage that only a single outlet valve can be provided must and nevertheless a large number of pressure reduction speeds can be achieved.

The system is advantageously used so that when the first rotation delay signal occurs Inlet valve is closed, one with the Outlet valve connected pressure cell that the dem Forwards the signal proportional to the control pressure to the evaluation circuit. When the second rotation delay signal occurs, one outlet valve is then activated as a result of the evaluation circuit delivered maximum voltage fully open. Allow both pressure reduction speeds the pressure reduction down to the value 0.

It is of course also possible to use a sensor with an evaluation circuit, for example. zen, which emits three delay signals to the outlet valve when the first rotation delay signal occurs, the voltage proportional to the brake or control pressure, when the second Rotation delay signal an amplified proportional Apply the voltage and only apply the maximum voltage when the third rotation delay signal occurs.

The concept of the invention is described with reference to the drawing. It shows

so Fig. I a schematic representation of the vehicle brake system, and

FIG. 2 shows a pressure-speed diagram of the vehicle brake system according to FIG. 1.

The essential parts shown in FIG. 1

The vehicle brake system presented has an actuation valve 1, an inlet valve 2 and a control valve. The control valve consists of a valve 3, an outlet valve 4 and a control piston 5, with corresponding housing and line connections in front.

M) are seen. Furthermore, a pressure cell 6, a sensor 7 and an electronic output holding device 8 are provided.

The actuating valve 1 is supplied by a compressed air supply device (not shown)

fts a line 9 is supplied. Compressed air is available at the same time via a line 10 to the valve 3 of the control valve. From the valve 3, the brake line 11 leads to Edge brake cylinder 12. Actuator I is with

3 4

connected to the inlet valve 2 via line 13, wäb- (Fig. 2 - I) through line 22 to the electronic Given a control line 14 to the inlet 15 on the outlet evaluation circuit 8, the outlet valve becomes 4 leads. Line 16 leads to a room 17 oil 4 through the line 21 to the electronic above the control piston 5. In the outlet valve 4 there is an evaluation circuit 8 pending, the pressure per outlet seat 18 provided, which opens into a leak 19, s portional electr. Voltage energized, the inlet valve 2 Via line 20, the pressure cell 6 is connected to the line blocks the passage to the control line 14, see above device 16 or the space 17 above the control piston S that by the leak generated at the outlet seat 18 19 connected. Compressed air escapes from room 17 to the atmosphere.

From the pressure measuring cell 6 there is an electrical proportional to that in the brake cylinder 12

Line 21 to the electronic evaluation circuit 8, io pending brake pressure also reduced, as in

on the other hand via an electrical line 22 with line 20 the electr.-pneum. Load cell 6

the sensor 7 is connected. A line 23 leads impacting, whereby at the same time the outlet

from the evaluation circuit to inlet valve 2, selector valve 4 via line 21, electronic evaluation

A line 24 leads to the outlet valve 4. circuit 8 and line 24 supplied electr.

Fi g. 2 shows a diagram in which the speed is reduced proportionally to the voltage and the leakage 19 is plotted against time and pressure. The outlet seat 18 controlled as a function of the pressure, the two upper curves represent the vehicle speed. The slowed pressure reduction (Fig. 2 - p) represents the speed ν F and the wheel speed vR . The signal marked on the curve of the wheel speed vÄ remains over the duration of the first rotational deceleration.
Points are assigned to the following signals: 20 Takes the. Despite the slow pressure reduction

I = occurrence of the first turning deceleration signal turning deceleration of the vehicle wheel (i ig. 2 - ν R)

II = occurrence of the second deceleration signal is continued, and the second rotation deceleration

III = elimination of the second rotation delay signal threshold exceeded and the second rotation delay

IV = occurrence of an acceleration signal. Approximation signal (Fig. 2 - II) of the electronic evaluation With ρ is a slow pressure reduction, with 25 teschaltung fed through line 22, the

pl a quick pressure reduction and with pl a pressure release valve through line 24 with the max

construction called. electr. Voltage excited so that the outlet seat 18 is full

The function of the system is as follows: When the brake is opened and space 17 is quickly vented, which means

Sen, compressed air from the actuating valve 1 passes through proportionally the brake pressure in the wheel brake cylinder

Line 13, inlet valve 2, control line 14, which is rapidly reduced (FIG. 2 - p1).

opened inlet 15 on outlet valve 4 and line 16 with elimination of the second rotation delay signal

in the space 17 in the control valve, at the same time by (F ig. 2 - III) by increasing the speed of the

Line 20 to the electro-pneum. Pressure cell 6. The vehicle wheel is the outlet valve 4 except for the

Proportional to the input pressure in room 17 is detected by the pressure cell 6 electr. Chip compressed air through line 11 to the brake cylinder 12 35 residual current de-energized, so that one in space 17 remains controlled, residual pressure only slowly through the throttle

If the braking effect generated by the brake pressure at the outlet seat 18 is reduced until a

force the acceleration signal (Fig. 2 - TV) which can be transmitted between the tire and the roadway via line 22

takes the rotational deceleration of the vehicle wheel quickly to the electronic evaluation circuit 8 and the Eii.-

to. If the first rotation delay threshold is supplied to the 40 or exhaust valves 2, 4. These are

The sensor 7 which detects the wheel speed is de-energized. A new pressure build-up begins

slide and the first rotation delay signal (Fig. 2 - p2).

1 sheet of drawings

Claims (2)

Patent claims: 1. Pressure medium-actuated and anti-lock vehicle brake system a) with inlet and outlet valves arranged between the supply and brake line, the Pressure is received from an actuating valve that can be operated by the driver and activated when the wheel is about to lock, b) a sensor that detects the wheel speed, the signal of which is an electronic one Evaluation circuit is supplied, which in turn a first rotation delay signal and a second signal corresponding to a large rotation deceleration threshold to the Inlet and outlet valve emits, c) when the first rotation delay signal occurs, the inlet valve closes and at the same time the outlet valve opens, which slowly causes the pressure in the Randhremszvlinder falls, d) when the second rotation delay signal occurs, the outlet valve releases an additional flow cross-section, so that the brake pressure decreases rapidly, characterized in that the outlet valve (4) contains a leak (19), and that a signal proportional to the control pressure is superimposed on the first rotation delay signal (I), and thus the flow cross-section of the leak (19) changes continuously in relation to the received signal. 2. Vehicle brake system i.ach claim 1, characterized in that a mv the outlet valve (4) connected to the pressure cell (6) the dem Forwards the signal proportional to the control pressure to the evaluation circuit (8).