Power plants – Pressure fluid source and motor – Apparatus having means responsive to or ameliorating the...
Patent
1996-03-07
1998-04-14
Richter, Sheldon
Power plants
Pressure fluid source and motor
Apparatus having means responsive to or ameliorating the...
60591, B60R 2100, B60T 700, F16D 6532
Patent
active
057379190
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a master cylinder comprising a body pierced with a bore closed on one side by an end and on the other by a piston which slides in this bore therein delimiting a pressure chamber which is connected to at least one brake motor through an outlet of this chamber and through a pressure pipe, the chamber and the pressure pipe together delimiting a working volume filled with a hydraulic fluid.
In practice, all master cylinders used in the hydraulic braking circuits of motor vehicles since the latter were invented correspond to this definition.
The improvement in safety standards has revealed the need to develop master cylinders in a way such that a frontal impact applied to the vehicle cannot easily be transmitted to the leg of the driver by the master cylinder, even when the impact occurs while he driver is pressing as hard as he can on the brake pedal.
The present invention falls within this context, and its object is to propose a master cylinder which meets this requirement.
To this end, the master cylinder of the present invention is essentially characterized in that the working volume is partially delimited by a leak-off device which, in response to an impact which is applied to it, selectively allows hydraulic fluid to leak off towards the outside of this working volume.
According to a first possible embodiment, the leak-off device essentially comprises a valve including a closure piece controlled by a push rod projecting out of the working volume, this valve being capable of opening the working volume to the outside in response to a translational movement carried out by the push rod under the effect of an impact.
In this case the valve exhibits, for example, a wall pierced with an orifice which reduces it to an annular surface surrounding this orifice, and the closure piece exhibits a shoulder which interacts with this annular surface, along a closed curve surrounding the orifice and by means of an annular seal, in order to close off the wall in a sealed fashion when this closure piece is in a position of rest.
The valve may comprise a cylindrical body outside the master cylinder, closed off by the closure piece and in which the latter is translationally mounted, or the wall of the valve may be made up of the end of the master cylinder, this valve thus being housed in the master cylinder and forming an integral part of the latter.
In any case it is preferable for the closure piece to be urged into a position of rest by a spring.
In another possible embodiment the leak-off device comprises a fragile hollow body, outside the master cylinder, and capable of breaking under the effect of an impact.
Other characteristics and advantages of the invention will emerge clearly from the description thereof which is given hereafter, by way of non-limiting indication, with reference to the appended figures, among which:
FIG. 1 is a view in partial section of a braking system incorporating a master cylinder in accordance with a first embodiment of the invention;
FIG. 2 is a view in partial section of such a master cylinder.
FIG. 3 is a view in partial section of a master cylinder in accordance with a variant of the first embodiment of the invention;
FIG. 4 is a view in partial section of a master cylinder in accordance with a second variant of the first embodiment of the invention;
FIG. 5 is a view in partial section of a master cylinder in accordance with a second embodiment of the invention; and
FIG. 6 is a view in partial section of a master cylinder in accordance with a variant of the second embodiment of the invention.
As FIG. 1 shows, a hydraulic braking system conventionally comprises a master cylinder 1 actuated by a pedal 2, usually through a booster servo 3 which amplifies the force exerted on the pedal 2.
The master cylinder 1 itself comprises (FIG. 2) a body 4 pierced with a bore 5 closed on one side by an end 6 and on the other by a piston 7 which slides in this bore therein delimiting a pressure chamber 8 which is connected to at least one brake motor 9, 10 through an outlet
REFERENCES:
patent: 5051063 (1991-09-01), Vasselet
patent: 5634337 (1997-06-01), Gautier et al.
Cobianchi Flavio
Gautier Jean Pierre
Perez Revilla Miguel
Verbo Ulysse
Bosch Systems de Freinage
McCormick Jr. Leo H.
Richter Sheldon
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