GB1596228A

GB1596228A - Vehicle braking system

Info

Publication number: GB1596228A
Application number: GB14859/78A
Authority: GB
Original assignee: Automobiles Peugeot SA; Automobiles Citroen SA
Current assignee: Automobiles Peugeot SA; Automobiles Citroen SA
Priority date: 1977-04-15
Filing date: 1978-04-14
Publication date: 1981-08-19
Also published as: DE2815527B2; DE2815527C3; FR2387146B1; IT1093944B; DE2815527A1; ES467738A1; FR2387146A1; IT7821735A0

Description

(54) A VEHICLE BRAKING SYSTEM (71) We, SOCIETE ANONYME AUTOMOBILES CITROEN, of 117 a 167 Quai André Citroën, 75747 Paris, Cedex 15, France and AUTOMOBILES PEUGEOT, of 75 avenue de la Grande Armee, 75016 Paris, France, both French Body Corporates, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to brake pressure limiters.

According to the present invention there is provided a vehicle having a braking system and a brake pressure limiter for limiting the maximum pressure applicable to the braking system, the limiter having an actuating member which is movable to alter the maximum pressure, a wheel assembly of the vehicle being connected to the body of the vehicle by a damper unit which has a part mounted pivotally on the body and which is arranged in such a way that displacement of the wheel assembly relative to the body causes angular displacement of that part relative to the body, the actuating member of the brake pressure limiter being resiliently connected to that part of the damper unit, whereby the position of the actuating member is a function of the load carried by the vehicle.

For a-better understanding of the present invention and to show how it may be carried into effect, reference will now be made, by way of example only, to the accompanying drawings, in which: Figure 1 is a general view in elevation of a brake pressure limiter connected to a damper unit; and Figure 2 is a general view elevation showing another form of connection between a brake pressure limiter and a damper unit.

Figure 1 shows a chassis of a vehicle to which is connected a brake pressure limiter 5 by means of screws 3 and 4 screwed onto a plate 2 which is welded onto the chassis 1.

One end of a hydropneumatic telescopic damper unit 7 is also connected to the chassis by a hinge 6. The other end of this damper unit 7 is anchored by a hinge 8 to a wheel support arm 9 forming part of a wheel assembly. The telescopic damper unit 7 is inclined to the vertical and comprises a protective member 10.

The brake pressure limiter has an actuating member in the form of a lever 11 which is mounted to pivot about an axis 12.

One end of the lever 11 has a cam surface 13 positioned to act on a piston or slide valve spool 14 of the braking pressure limiter (see Figure 2). The other end 15 of the lever 11 is connected to one end 16a of a resilient member constituted by a spring 16; the other end 16b of the spring 16 is connected to that member of the telescopic damper unit 7 which is secured to the spring part of the vehicle, i.e. the chassis 1.

In the embodiment of Figure 1, the end 16b of the spring 16 is provided with a hook engaged in a hole in a lug 18 which is welded on to the protective member 10 of the telescopic damper unit 7.

In the embodiment of Figure 2, the end 16b of the spring 16 engages a hole in a spring fitting 21 mounted at the end of a lever 22 which is welded on to a sleeve which forms part of the hinge 6; the end 16b is clamped in the spring fitting by a screw 23.

In operation of the limiter, as shown in Figure -2, the cam surface 13 operates the slide valve spool 14, a groove 25 in the spool 14 normally connecting an inlet 26 with an outlet 27 leading to the brakes. The outlet side is also connected to a chamber 28 containing a spring 29 biasing the slide valve 14 towards a position in which the inlet and the outlet 27 are in communication. A nonreturn valve 31 is provided between the chamber 28 and the inlet 26.

Operation is as follows: Due to the oblique position of the telescopic damper unit, vertical movement of the vehicle chassis I when the load changes gives rise to changes in the position of the lower end of the damper unit between the points P1 (vehicle empty) and P2 (vehicle fully loaded). The axis of the damper unit is displaced angularly between the positions A, (vehicle empty) and A2 (vehicle fully loaded). It is possible for the damper unit to make vertical movements up to point P3 and angular displacements as far as the position A3 to absorb bumps in the ground and vehicle movements caused by acceleration and deceleration. It will be appreciated that the angular displacements of the damper unit 7 are relatively small compared to the displacement of the wheel assembly 9.

In the embodiment of Figure 1, the damper unit 7 is positioned such that its axis is disposed somewhere between the axes A1 and A2 depending on the load carried by the vehicle. When the vehicle is unladen, the axis of the damper unit lies on the axis A1, while when the vehicle is loaded, the damper unit pivots about the hinge 6 to the right. The protective member 10 pulls the lever 11 anti-clockwise through the spring 16, the lever 11 pivoting about the axis 12 so that the cam 13 bears on the valve spool 14 and, when the cam engages the spool 14, further movement stresses the spring 16.

In the embodiment of Figure 2, the pivoting of the damper unit 7 at the hinge 6 causes the lever 22 to be rotated which first pivots the lever 11 through the spring 16 until the cam 13 bears on the valve spool 14 and which then stresses the spring 16 to a greater or lesser extent according to the load of the vehicle.

When the brake is operated by the driver, there is produced in the chamber 28 a pressure which exerts a force on the valve spool 14 in a direction opposite to the force exerted by the spring 16. When the force exerted by the braking pressure exceeds the force exerted by the spring 16, the valve spool is displaced in such a way to cause the brake supply duct to close and the lever 11 to pivot about the axis 12 and consequently to increase the tension of the spring 16.

When the driver releases the brakes, the pressure at the inlet 26 is relieved and the valve 31 opens, permitting the pressure in the chamber 28 to fall until the valve spool 14 is displaced to cause the brake supply duct to open under the action of the lever 11 and the spring 29, the spring 16 then relaxing., The embodiment in which the lever 22 is connected to the sleeve of the hinge 6 is advantageous in that it avoids distortions of the protective member or sleeve 10 which may be made of plastics or sheet metal.

WHAT WE CLAIM IS: 1. A vehicle having a braking system and a brake pressure limiter for limiting the maximum pressure applicable to the braking system, the limiter having an actuating member which is movable to alter the maximum pressure, a wheel assembly of the vehicle being connected to the body of the vehicle by a damper unit which has a part mounted pivotally on the body and which is arranged in such a way that displacement of the wheel assembly relative to the body causes angular displacement of that part relative to the body, the actuating member of the brake pressure limiter being reiliently connected to that part of the damper unit, whereby the position of the actuating member is a function of the load carried by the vehicle.

2. A vehicle as claimed in claim 1, in which the damper unit is a telescopic damper unit.

3. A vehicle as claimed in claim 2, in which the said part of the damper unit is a protective member.

4. A vehicle as claimed in any one of the preceding claims, in which the actuating member is connected to a lever which is secured to a sleeve of the said part which sleeve affords the pivotal connection between the damper unit and the body.

5. A vehicle as claimed in any one of the preceding claims, in which the actuating member is resiliently connected to the said part by a tension spring.

6. A vehicle as claimed in any one of the preceding claims, in which the actuating member comprises a pivotal lever which comprises a cam surface for engagement with a valve spool of the limiter.

7. A vehicle substantially as described herein with reference to the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. of the lower end of the damper unit between the points P1 (vehicle empty) and P2 (vehicle fully loaded). The axis of the damper unit is displaced angularly between the positions A, (vehicle empty) and A2 (vehicle fully loaded). It is possible for the damper unit to make vertical movements up to point P3 and angular displacements as far as the position A3 to absorb bumps in the ground and vehicle movements caused by acceleration and deceleration. It will be appreciated that the angular displacements of the damper unit 7 are relatively small compared to the displacement of the wheel assembly 9. In the embodiment of Figure 1, the damper unit 7 is positioned such that its axis is disposed somewhere between the axes A1 and A2 depending on the load carried by the vehicle. When the vehicle is unladen, the axis of the damper unit lies on the axis A1, while when the vehicle is loaded, the damper unit pivots about the hinge 6 to the right. The protective member 10 pulls the lever 11 anti-clockwise through the spring 16, the lever 11 pivoting about the axis 12 so that the cam 13 bears on the valve spool 14 and, when the cam engages the spool 14, further movement stresses the spring 16. In the embodiment of Figure 2, the pivoting of the damper unit 7 at the hinge 6 causes the lever 22 to be rotated which first pivots the lever 11 through the spring 16 until the cam 13 bears on the valve spool 14 and which then stresses the spring 16 to a greater or lesser extent according to the load of the vehicle. When the brake is operated by the driver, there is produced in the chamber 28 a pressure which exerts a force on the valve spool 14 in a direction opposite to the force exerted by the spring 16. When the force exerted by the braking pressure exceeds the force exerted by the spring 16, the valve spool is displaced in such a way to cause the brake supply duct to close and the lever 11 to pivot about the axis 12 and consequently to increase the tension of the spring 16. When the driver releases the brakes, the pressure at the inlet 26 is relieved and the valve 31 opens, permitting the pressure in the chamber 28 to fall until the valve spool 14 is displaced to cause the brake supply duct to open under the action of the lever 11 and the spring 29, the spring 16 then relaxing., The embodiment in which the lever 22 is connected to the sleeve of the hinge 6 is advantageous in that it avoids distortions of the protective member or sleeve 10 which may be made of plastics or sheet metal. WHAT WE CLAIM IS:

1. A vehicle having a braking system and a brake pressure limiter for limiting the maximum pressure applicable to the braking system, the limiter having an actuating member which is movable to alter the maximum pressure, a wheel assembly of the vehicle being connected to the body of the vehicle by a damper unit which has a part mounted pivotally on the body and which is arranged in such a way that displacement of the wheel assembly relative to the body causes angular displacement of that part relative to the body, the actuating member of the brake pressure limiter being reiliently connected to that part of the damper unit, whereby the position of the actuating member is a function of the load carried by the vehicle.