Power plants – Pressure fluid source and motor – Pulsator
Patent
1997-12-16
2000-03-28
Lopez, F. Daniel
Power plants
Pressure fluid source and motor
Pulsator
91376R, 921691, B60T 1300
Patent
active
060416017
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a braking device composed of a master cylinder and of a pneumatic booster, the booster especially comprising: a rigid casing; a moving partition delimiting at least one front chamber and one rear chamber, in a leaktight fashion, within the casing; a three-way valve which can be operated by a control rod in order selectively to allow different pressures in the front and rear chambers and correspondingly subject the moving partition to a boost force which acts in a first axial direction pointing towards the master cylinder; and a push rod connected to the moving partition for operating the master cylinder, the casing comprising a front shell secured to the master cylinder and forming a wall for the front chamber, and a rear shell forming a wall for the rear chamber.
BACKGROUND OF THE INVENTION
Devices of this type are well known in the prior art, as represented, for example, by Patent Document EP-0,664,752.
The tightening of safety standards during the last decade has revealed the need to further develop motor vehicle braking devices, and particularly boosters, in such a way that a frontal or oblique impact on the vehicle cannot readily be transmitted to the driver's leg even when the impact occurs while the driver is depressing the brake pedal as hard as he can.
Numerous solutions have been developed in an attempt to solve this problem, many of which prove highly satisfactory for a certain number of cases.
The fact still remains that the braking device for a vehicle is still installed in the engine bay of this vehicle and that the internal layout of the engine compartment of one vehicle is always practically specific to this vehicle, which means that a solution which can be employed successfully in the given vehicle may prove devoid of positive effect for some other vehicle.
SUMMARY OF THE INVENTION
The invention falls within this context and aims to provide a novel solution capable satisfactorily of limiting the transmission of a frontal or oblique impact in configurations where the known solutions do not prove effective enough.
To this end, the device of the invention is essentially characterized in that the front shell of the booster comprises a peripheral part of larger relative diameter secured to the rear shell, and a central part of smaller relative diameter secured to the master cylinder, and in that the peripheral part and the central part overlap in an annular overlap region, and in that in the overlap region the peripheral part is at least locally further forward than the central part in the first axial direction.
Thanks to this layout, the two parts of the front shell of the booster may, in the event of an impact, become detached from one another without transmitting any substantial force to the driver, the detaching of these two parts even playing a part in absorbing kinetic energy.
In one possible embodiment of the invention, the central part and the peripheral part are locally secured to each other in a non-uniform manner in the overlap region.
For example, the central part and the peripheral part may be bonded or welded together at points, the spots of adhesive or of welding being unevenly distributed around the overlap region to reveal a favoured connection region defined by a relatively high density of spots of adhesive or of welding, and a favoured breakage region defined by a relatively low density of spots of adhesive or of welding.
In an advantageous arrangement, the central part may furthermore be fitted, in the overlap region, into a fold in the peripheral part.
In the latter case, and for a booster in which the moving partition has a circular rim, the fold in the peripheral part is preferably shaped in such a way as to allow the central part in the overlap region to accommodate the rim of the moving partition.
The diameter of the central part may also be chosen to be at most equal to half the diameter of the peripheral part, to make it easier for these two parts to become detached in the event of an oblique or lateral impact.
In the latter case
REFERENCES:
patent: 3552272 (1971-01-01), Parsons
patent: 5634337 (1997-06-01), Gautier et al.
patent: 5797264 (1998-08-01), Verbo et al.
patent: 5941610 (1999-08-01), Hayashi et al.
Leboisne Cedric
Verbo Ulysse
Bosch Systemes de Freinage
Comstock Warren
Lopez F. Daniel
McCormick, Jr. Leo H
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