Power plants – Pressure fluid source and motor – Pulsator
Patent
1993-09-30
1995-12-19
Look, Edward K.
Power plants
Pressure fluid source and motor
Pulsator
913691, 91376R, B60T 1300, F15B 910
Patent
active
054759773
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a brake-booster device for a motor vehicle, comprising on the one hand a master cylinder filled with a brake fluid and fitted with a main hydraulic piston designed to receive an actuation force composed of an input force and of a boost force both acting in an axial direction, and on the other hand a pneumatic booster capable of being controlled by application of said input force on a control rod controlling the opening of a valve, so as to exert said actuation force on the main hydraulic piston, the booster comprising a rigid casing separated in a leak-tight manner into two chambers by means of at least one movable partition, capable of being acted upon by a pressure differential between the two chambers resulting from the opening of the valve and of driving a pneumatic piston, movable with respect to the casing, bearing said valve and contributing mat least to transmission of said boost force, the main hydraulic piston of the master cylinder itself comprising a hollow, movable cylinder receiving at leas part of the boost force, and inside which slides, in a leaktight manner and in the axial direction, a secondary hydraulic piston capable of receiving at least said input force.
A device of this type is well known in the prior art and is for example described in U.S. Pat. No. 4,491,058 or in the document FR-A-2 558 126.
Such a device, using a movable pneumatic piston, has the advantage of offering to the brake pedal a long travel when braking, which permits an optimal control of the deceleration of the vehicle.
However, the generalization of electronically controlled brake systems, designed to prevent locking of the wheels and/or wheelspin, is giving rise to new constraints on the response times of the mechanical and hydraulic subassembly, the electronic subassembly having, for its part, extremely short response times.
In this context, the invention has precisely the object of reducing the response time of a brake-booster device.
To this end, the device of the invention is essentially characterized in that at least one opening is made in the movable cylinder in order to place the interior of the latter in communication with the interior of the master cylinder, and in that a selective flow-rate reducer is provided in, this opening in order to oppose, in a circulation of brake fluid from the master cylinder to the movable cylinder, and a circulation in the reverse direction, respective first and second pressure drops, the first of which is greater than the second.
By virtue of this arrangement, the secondary hydraulic piston, during an abrupt braking action, receives the reaction of the internal pressure of the master cylinder only in a progressive and deferred manner.
The first result of this is that the control rod remains for a longer time in a position relatively advanced, in the direction of the master cylinder, compared with the pneumatic piston, which consequently permits the valve to remain more widely open for a longer time, and permits the boost force to become established more rapidly at a high value.
In an embodiment easy to implement, several openings are made in the movable cylinder and the selective flow-rate reducer is a non-return valve installed on at least one of these openings.
Preferably, the device further comprises a thrust rod of adjustable length disposed between the control rod and the secondary hydraulic piston.
The invention will now be described by way of example with reference to the accompanying drawings in which: embodiment of the present invention, and variant of the embodiment of FIG. 1.
Insofar as the invention relates only to an improvement made to pneumatic brake-booster systems, and insofar as the general constitution and the functioning of the latter are well known to the person skilled in the art, these systems will be rapidly recalled here only to permit a total comprehension of the improvement which the invention represents.
Diagrammatically, a system of this type comprises a booster 1 and a master cylinder 2.
The booster itself compri
REFERENCES:
patent: 3470695 (1969-10-01), Kilb
patent: 4012080 (1977-03-01), Engle
patent: 4110985 (1978-09-01), Gordon et al.
patent: 4195484 (1980-04-01), Mathues et al.
Gautier Jean Pierre
Levrai Roland
Perez Revilla Miguel
Verbo Ulysse
Allied Signal Europe Services Techniques
Look Edward K.
McCormick Jr. Leo H.
Nguyen Hoang
Palguta Larry J.
LandOfFree
Brake-booster device with slowed hydraulic reaction does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Brake-booster device with slowed hydraulic reaction, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Brake-booster device with slowed hydraulic reaction will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-986365