Fluid-pressure and analogous brake systems – Speed-controlled – Having a valve system responsive to a wheel lock signal
Patent
1993-02-01
1994-07-26
Butler, Douglas C.
Fluid-pressure and analogous brake systems
Speed-controlled
Having a valve system responsive to a wheel lock signal
303 61, 3031192, 1376275, B60T 832, B60T 848, B60T 836
Patent
active
053323041
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND
The present invention relates to a hydraulic brake system with anti-lock control, in particular for automotive vehicles.
A brake system is known already from the technical leaflet of Robert Bosch GmbH "Pkw-Bremsanlagen" (passenger vehicle brake systems), first edition, page 17, picture 36. In this brake system the modulated braking pressure has a reactive effect on the brake pedal during the anti-lock control, since the auxiliary-pressure pump is directly connected to the tandem master cylinder. Due to this design of circuit configuration the brake system described above does not perform an anti-lock control operation with the given means without pedal pulsation and without valve switch noises caused by the digital control of the inlet and outlet valve designed as a three-way/three-position directional control valve combination.
SUMMARY OF THE INVENTION
Therefore, it is an object of the present invention to avoid the shortcomings described hereinabove in respect of the state of the art in order to attain a low-cost and noise-minimized brake system by using simple means while maximum reliability in function is maintained. The brake system of the present invention allows a reaction-free positioning of the brake pedal during the braking pressure modulation without taking special measures on the master cylinder.
This object is achieved according to the present invention wherein the auxiliary pressure line connected to the pressure side of an auxiliary pressure pump constitutes a permanent direct hydraulic connection to a wheel brake while bypassing the inlet valve, the permanent hydraulic connection established between the auxiliary pressure pump and the wheel brake being adapted to be isolated from the master cylinder by the inlet valve.
The measures disclosed afford expedient embodiments of the present invention which will be described and explained in more detail hereinbelow with respect to further features and advantages of the invention by way of the accompanying drawing.
DESCRIPTION OF THE DRAWING
FIG. 1 shows a principal circuit configuration of an anti-lock brake system as well as a longitudinal cross-sectional view of an expedient structural embodiment of the valve assembly.
DETAILED DESCRIPTION
A main pressure line 9 connects a master cylinder 5 with at least one wheel brake 3 as long as an inlet valve 4 inserted into the main pressure line 9 and designed as a non-return valve persists in its normal position allowing pressure fluid passage. The normal position of the inlet valve 4 is determined by an electromagnet 10 which is normally de-energized. Electromagnet 10 has a magnet armature 8 which is provided with a tappet 11 on either frontal end and which is held in its normal position by a compression spring 12 which urges the armature in the direction of the inlet valve 4. In the disclosed embodiment, inlet valve 4 is designed as a spherical seat valve. Thus the right-hand tappet 11 in the drawing keeps the inlet valve 4 open in opposition to the effect of a conical spiral spring 16 abutting the inlet valve. Arranged diametrically relative to the inlet valve 4 on the left side of the magnet armature 8 is the outlet valve 6 which is closed in the release position of the brake according to the drawing. Said outlet valve 6 is designed as a spherical non-return valve which acts to close in the direction of the magnet armature 8. In the opening direction of the outlet valve 6, a return delivery line 13 succeeds the suction side of an auxiliary pressure pump 1 and accommodates a pressure fluid accumulator 14 in a branch line. An auxiliary pressure line 2 arranged on the pressure side of the auxiliary pressure pump 1 terminates into the main pressure line 9 which is disposed downstream of the inlet valve 4 and leads directly to the wheel brake 3.
Operation
In the position of brake release or the normal braking position activated by pedal force according to the drawing, the compression spring 12 retains the magnet armature 8 in the position in which the inlet valve 4 is mechanically
REFERENCES:
patent: 4068904 (1978-01-01), Blomberg et al.
patent: 4892362 (1990-01-01), Takata
patent: 4940295 (1990-07-01), Adachi et al.
Alfred Teves GmbH
Ballato Josie A.
Butler Douglas C.
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