초록 ▼

An antilocking braking system for a road vehicle performs brake pressure control on the principle of changing the volume of an output pressure chamber of a pressure modulator connected to the wheel brake. The modulator has a control pressure chamber which is separated by a piston from the output pre

An antilocking braking system for a road vehicle performs brake pressure control on the principle of changing the volume of an output pressure chamber of a pressure modulator connected to the wheel brake. The modulator has a control pressure chamber which is separated by a piston from the output pressure chamber into which the output pressure of an auxiliary pressure source is permanently introduced via an inlet control valve. The piston is held in its end position associated with minimal volume of the output pressure chamber. Connected in series with the inlet control valve is a non-return valve which prevents a drop in the pressure in the control pressure chamber in the event of a failure of the auxiliary pressure source. Volume increases in the output pressure chamber required for pressure reduction phases of the antilock braking control are controlled by an outlet control valve. It is possible to block off the output pressure chamber from the brake booster for the duration of antilock braking control cycles. The pressure modulator is equipped with a position sensor which generates output signals characteristic of the piston position. The modulator piston is displaced in the sense of an increase in the volume of the output pressure chamber by a resilient restoring element. With the aid of a test valve, periodic reductions in the output pressure of the auxiliary pressure source can be controlled. The piston displacements occurring as a consequence of such pressure reductions and sensed by the position sensor are signalled as an indication of leakage of the non-return valve.

대표청구항 ▼

A system for checking the tightness of a safety-relevant valve in an antilock braking system for a road vehicle with hydraulic multiple circuits, comprising an auxiliary pressure source having a pressureless reservoir; a pressure modulator which controls brake pressure by changing the volume of an o

A system for checking the tightness of a safety-relevant valve in an antilock braking system for a road vehicle with hydraulic multiple circuits, comprising an auxiliary pressure source having a pressureless reservoir; a pressure modulator which controls brake pressure by changing the volume of an output pressure chamber of the pressure modulator connected to a wheel brake to be controlled and which includes a piston separating the output pressure chamber from a control pressure chamber in a pressure-tightly movable manner, which piston is urged by valve-controlled pressurization of the control pressure chamber under a output pressure of the auxiliary pressure source into one end position associated with minimal volume of the output pressure chamber and assigned to normal braking operation unsubjected to an antilock braking control and displaceable by valve-controlled pressure relief of the control pressure chamber for an increase in the output pressure chamber in order to reduce brake pressure in the wheel brake connected to the modulator; an inlet valve for introducing pressure into the control pressure chamber; a non-return valve connected between a control connection of the control pressure chamber and the output pressure of the auxiliary pressure source hydraulically in series with the inlet control valve bringing about the pressure introduction into the control pressure chamber, the non-return valve being blocked by relatively higher pressure in the control pressure chamber of the pressure modulator than at the output of the auxiliary pressure source; an outlet control valve blocking the control pressure chamber in its basic position and in its open position relieving the control pressure chamber with respect to the pressureless reservoir of the auxiliary pressure source; the pressure modulator further including a prestressed restoring spring acting on the modulator piston for displacement of the piston bringing about an increase in the volume of the output pressure chamber while allowing the modulator piston to be held in its end position corresponding to minimal volume of the output pressure chamber by the auxiliary pressure introduced into the control pressure chamber against the restoring force of the spring and against the brake pressure which can be introduced by the brake booster into the output pressure chamber; a position sensor for monitoring the position of the modulator piston and generating an electric output signal characteristic at least of changes of the piston position; and an electrically operable test valve for selectively connecting the pressure output of the auxiliary pressure source to the pressureless reservoir of the auxiliary pressure source to achieve a pressure drop in the pressure supply line leading to the pressure modulator.