Fluid-pressure and analogous brake systems – Speed-controlled – Having a valve system responsive to a wheel lock signal
Patent
1993-09-30
1995-02-14
Oberleitner, Robert J.
Fluid-pressure and analogous brake systems
Speed-controlled
Having a valve system responsive to a wheel lock signal
303 11, 303DIG2, B60T 1314
Patent
active
053888987
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention is concerned with a hydraulic brake system including an anti-locking control, in particular for use with automotive vehicles,.
A brake system of the afore-mentioned type is disclosed in German Patent Application No. P 40 15 882 which is concerned with a so-called closed anti-locking control system (ASS) which, as opposed to the state-of-the-art open anti-locking control systems, does not have a direct connection of the auxiliary pressure and return-flow system to the non-pressurized supply tank provided on the master cylinder side. The auxiliary pressure system, during the brake slip control, withdraws from the low-pressure accumulator disposed on the return-flow conduit to the pump the required pressure fluid volume, conveying the same to the master cylinder pressure conduit. At the same time, excess pressure fluid is supplied to a high-pressure accumulator provided in the branch conduit leading to the auxiliary pressure conduit, with the pressure level of the high pressure accumulator being adjusted through a pressure relief valve coupled thereto. In response to the electromagnetic actuation of the inlet and outlet valves disposed in the master pressure conduit and the return conduit, the anti-locking control is then effected in the associated wheel brakes.
The circuit configuration involved does not enable the afore-described brake system to control the start-up and traction slip, respectively. Actuation of the pump in response to traction slip, inevitably, would result, as a consequence of the pedal being in the release position, in a return flow of pressure fluid to the supply tank rather than to the wheel brake.
It is, therefore, the object of the present invention to improve a brake system having the afore-described features so as to enable, by substantially preserving the basic circuit configuration, in particular, the control system, a low-cost improvement of the traction slip control with no need for enhancing the electronic controls of the brake system.
SUMMARY OF THE INVENTION
This problem is solved through the provision of a multi-way valve substantially controlled by the auxiliary pressure, the brake pressure generator isolated from the controlled wheel brake by the multiway valve. The hydraulic actuation involves a switching pattern which may be carried out with minimal electronic controls.
One embodiment of the invention provides, in a first switching condition, a pressure fluid connection between the multi-way valve, configured as a 2-way/2-position valve, and the auxiliary pressure conduit, through a 3-way/2-position valve to which the pressure of the brake pressure generator can be applied. In a second switching condition, the 3-way/2-position valve enables a hydraulic connection between the multi-way valve and a pressure fluid supply line connecting the pump intake conduit to the main pressure conduit. The 3-way/2-position valve insures the proper application of auxiliary pressure to the system coupled to the pump, with the multi-way valve, initially, being held, by a compression spring, in the basic condition.
Alternatively, the multiway-valve may be configured as a 4-way/2-position valve which, in a first switching condition, opens the main pressure conduit and closes a by-pass line connecting the auxiliary pressure conduit to the intake conduit. The by-pass line has in series, a throttle element and a switched-open blocking element to apply hydraulic pressure of a defined volume to a first control conduit coupled upstream of the throttle element and actuating the multi-way valve.
To preclude, on the one hand, an in-flow of pressure fluid from the intake conduit and, hence, an inadvertent switch-over of the 4-way/2-position valve, and to insure, on the other hand, the switch-over pressure required for the switch-over of the 4-way/2-position valve, a throttle and locking element is series connected to the by-pass line.
A second control conduit may be connected influencing the basic position of the multi-way valve to the brake pressu
REFERENCES:
patent: 4618189 (1986-10-01), Nakanishi et al.
patent: 4703979 (1987-11-01), Nakanishi et al.
patent: 4750788 (1988-06-01), Seibert et al.
patent: 5152589 (1992-10-01), Ocvirk
patent: 5209552 (1993-05-01), Reinartz et al.
patent: 5213399 (1993-05-01), Burgdorf et al.
Reinartz Hans-Dieter
Steffes Helmut
Lewis J. Gordon
Muratori Alfred
Oberleitner Robert J.
Seitter Robert P.
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