JPH0156011B2 - - Google Patents

Description

Detailed Description of the Invention [Industrial Application Field] The present invention provides a braking force adjustment device operated by a pressure medium for a vehicle having an air spring bellows or a hydraulic axle compensator. a regulating device for adjusting the brake pressure regulating valve in relation to the brake pressure regulating valve, the brake pressure regulating valve receiving a control pressure in relation to the load of the air spring bellows or hydraulic axle compensator, from no load to full load. Adjustment is made via an adjustment member that engages with a control ramp of the control piston of the adjustment device, such that the return of the control piston from a position corresponding to full load to a position corresponding to no load is in the opposite direction to the control pressure. It relates to a load-related braking force adjustment device which is carried out by an acting return spring.

[Conventional technology]

Such a braking force adjustment device is known from German Patent Application No. 1052441.
It is used to adapt the braking pressure in the braking cylinder to the loading conditions of vehicles with air spring bellows or hydraulic axle compensators. This adaptation takes place automatically by adjusting the height of the braking pressure supplied from the brake valve to the brake cylinder via a brake pressure regulating valve by means of a control pressure of a regulating device that is dependent on the axle load. .

This device is required to be able to stop the vehicle under effective conditions for predetermined auxiliary braking even if the pressure in the axle spring bellows disappears.

In other cases, when the control pressure disappears, even with a fully loaded vehicle, only a braking action corresponding to that of an unloaded vehicle is obtained, that is, no predetermined braking action is obtained.

A braking force regulator is also known from DE 20 57 973 A1, in which the no-load position is controlled via a control ramp by a control piston under the pressure of an air spring bellows. In this device, when the pressure in the air spring bellows disappears, the return spring moves the control piston with the control slope,
The actuating member resting on the highest position of this control ramp provides the required height of braking pressure for a fully loaded vehicle.

Vehicles Depending on the conditions of vehicle use, especially in the field of commercial vehicles, unfavorable adjustment values (spring constants, control pressures,
(braking pressure), the return spring designed for normal driving mode, due to the large spring constant required for this driving mode, moves to a controlled ramp position that guarantees reliable braking of the fully loaded vehicle. Unable to switch control piston.

[Problem to be solved by the invention]

SUMMARY OF THE INVENTION The object of the invention is to provide a braking force adjustment device which makes it possible to reliably switch the control piston into an emergency braking position corresponding to a predetermined load when the control pressure disappears.

[Means for Solving the Problem] In order to solve this problem, according to the present invention, an additional spring having a smaller spring constant is provided in series with the return spring, and the position corresponding to the no-load state of the control piston is The control piston is provided with an additional ramp that rises in the direction opposite to the position corresponding to the full load, starting from engaging the adjustment member of.

〔Effect of the invention〕

An additional spring, which is connected in series with the return spring and which can be installed space-savingly in the return spring due to its small spring constant, is advantageous when the return spring with a large spring constant is used during normal operation of the braking force regulator. Since it is in equilibrium with the control pressure acting on the control piston, it is in a state of no action. If, upon disappearance of the control pressure, the return spring is able to switch the control piston into the position in which the additional ramp is active, the additional spring remains inactive. Only when this condition is not met does an additional spring with a small spring constant act,
Switch the control piston to the position where the additional slope acts. In this case, if the full braking action for a fully loaded vehicle is also performed on an unloaded vehicle, overbraking (wheel locking) will occur, so the height of the additional slope corresponds to the braking action for a half loaded vehicle. It is better to choose height.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

The braking force regulating device according to the invention essentially consists of a braking pressure regulating valve 3 and an adjusting device 2 for adjusting the braking pressure regulating valve 3 as a function of the load.

The brake pressure regulating valve 3 itself is well known, and the simplest example thereof is illustrated. This regulating valve 3 has in its housing braking pressure regulating pistons 23, 24 which are designed as stepped pistons, the stepped pistons comprising a hollow piston 23 and a diaphragm 2.
It consists of 4. A movable compound valve body 25 is provided within the piston 23 and is loaded by a spring 26 and together with an inlet valve seat 19 formed on the inward flange of the piston 23 constitutes an inlet valve 25,19.

A hollow push rod 1 serving as an adjustment member of an adjustment device 2 to be described later is formed with an outlet valve seat 27 at its upper end.
Together with the composite valve body 25, outlet valves 25 and 27 are configured. The center hole 22 of the push rod 1 communicates with the atmosphere as an exhaust passage. The space below the inlet valve seat 19 of the piston 23 is a space 28 below the diaphragm 24.
It communicates with the brake cylinder through a connection port 21. Space 29 above the inlet valve seat 19
is supplied with braking pressure from a braking valve via a connection port 20.

When a brake valve (not shown) is operated in the illustrated non-operating position of the regulating valve 3, the brake pressure generated in the chamber 29 via the connection port 20 is applied to the stepped piston 2.
3 and 24 to push down this piston.
The composite valve body 25 follows the movement of the piston under the action of a spring 26 and hits the upper end of the push rod 1 formed as an outlet valve seat 27, thus closing the outlet valves 25, 27 and causing the pistons 23, 24 to descend further. Then, the composite valve body 25 is separated from the inlet valve seat 19 by the push rod 1, and the inlet valves 25, 19 are opened. Compressed air now flows from the connection 20 into the space 29 and into the opened inlet valve 2.
5, 19, and space 28, it can flow into the brake cylinder from the connection port 21.

Once a braking pressure is established in the braking cylinder, this pressure, which is also present in the space 28, will cause the piston 23,
24 upward again and inlet valves 25, 19.
, the braking end position can be obtained. Outlet valves 25, 27 are also in a closed state. The pressure present in the brake cylinder assumes a value which is regulated by the push rod 1 in dependence on the load via the brake pressure regulating valve 3.

After the braking process ends, the braking pressure applied to the connection port 20 and the space 29 disappears, so that the piston 23,
24 again assumes the position shown and the compressed air in the brake cylinder flows through the now open outlet valves 25, 2.
7, and is discharged to the atmosphere through the exhaust passage 22 of the push rod 1.

Now, the lower end (roller) 4 of the push rod 1 has a control slope 5 formed by the conical surface of the hollow control piston 6.
It's listed above. The lowest point of this control slope 5 is the no-load position corresponding to the empty state of the vehicle,
The highest point is the full load position of maximum load. The push rod end 7 of the control piston is movably supported in a control cylinder 8 in a gas-tight manner. In the embodiment shown, the control cylinder 8 is pressurized via control connections 9 and 10 from two control circuits (not shown), and these pressures supply pressure chambers 11 and 12 arranged in tandem in the control cylinder 8. via which it acts in one direction (to the left) on the control piston 6.

A return spring 13 is provided in the hollow chamber 14 of the control piston 6, the stress of which acts against and counterbalances the control pressure acting on the control piston 6. The preload of this spring 13 can be adjusted by means of a screw 15.

According to the present invention, an additional spring 16 having a smaller spring constant than the return spring 13 is provided within the return spring 13,
It is connected in series to the return spring 13 via a pot-shaped intermediate piece 17. As long as the force of the return spring 13 is balanced by the control pressure acting on the right side of the control piston 6, the right end of the return spring 13 rests via the intermediate piece 17 against the bottom of the hollow chamber 14 of the control piston 6, so that Additional spring 16 does not act.

An additional slope 18 for emergency braking is formed in the direction opposite to the slope 5 from the lowest unloaded position of the control slope 5 supporting the lower end 4 of the push rod 1 and extends to a height opposite to half load. ing.

A brake pressure regulating valve is mounted on the vehicle body and connected via a conduit to an air spring bellows or hydraulic axle compensator mounted on the axle.

When the vehicle is unloaded, there is a minimum pressure in the air spring bellows or the hydraulic axle compensator and the control piston 6 is in an axial position in which the push rod 1 against the control ramp 5 assumes its minimum position.

When the vehicle is loaded, the pressure in the air spring bellows or the hydraulic axle compensator increases and the pressure in the chambers 11 and 1 increases via the connections 9 and 10 of the control cylinder 8.
The compressed air flowing into 2 transmits this pressure increase to the control piston 6, so that this control piston moves to the left in the direction of the full load position. The resulting change in the position of the push rod 1 results in a load-related adjustment of the braking pressure flowing from the connection port 20 via the connection port 21 into the brake cylinder.

Now, if the control pressure supplied to the control cylinder 8 disappears due to leakage, the ideal position for the control piston 6 should be the half-load position. Since there is no more control pressure acting on the control piston 6, the additional spring 16 can now act and, if necessary together with the return spring 13, pushes the control piston 6 to the right so that the push rod 1 is pushed by the additional slope 18. Push up to the position corresponding to half load. In this way, emergency braking can be applied even on an unloaded vehicle without locking the wheels.

[Brief explanation of drawings]

The figure is a sectional view of a load-related braking force adjustment device according to the invention. DESCRIPTION OF SYMBOLS 1... Adjustment member, 2... Adjustment device, 3... Braking pressure regulating valve, 5... Control slope, 6... Control piston, 13...
Control spring, 16...Additional spring, 18...Additional slope.

Claims (1)

[Scope of Claims] 1. A braking force regulating device operated by a pressure medium of a vehicle with an air spring bellows or a hydraulic axle compensator has a braking pressure regulating valve and a braking force regulating valve that adjusts this braking pressure regulating valve in dependence on the load. It consists of an adjustment device that
The braking pressure regulating valve is adjusted from no load to full load via an adjusting member that engages a control ramp of a control piston of the adjusting device which receives a control pressure that is dependent on the load of the air spring bellows or the hydraulic axle compensator. ,
In those in which the return of the control piston from the position corresponding to full load to the position corresponding to no load is effected by a return spring acting in the opposite direction to the control pressure, from this in series with the return spring 13 An additional spring 16 is provided with a small spring constant;
An additional ramp 18 is provided on the control piston 6, which starts from a position corresponding to no load on the control piston 6 and rises in the opposite direction to the position corresponding to full load, so that the load on the additional spring 16 upon disappearance of the control pressure Load-related braking force adjustment device, characterized in that an additional bevel 18 of the control piston 6, which moves under the influence, engages an adjustment member 1 of the adjustment device 2. 2 The return spring 13 is connected to the hollow chamber 14 of the control piston 6
Device according to claim 1, characterized in that it is located within. 3. Device according to claim 1, characterized in that an additional spring 16 is provided in the return spring 13. 4. According to one of claims 1 to 3, the return spring 13 and the additional spring 16 are connected by a pot-shaped intermediate piece 17 that accommodates the additional spring 16. equipment. 5. Device according to one of the claims 1 to 4, characterized in that the preload of the return spring 13 is adjustable by means of a screw 15.