Power plants – Pressure fluid source and motor – Pulsator
Reexamination Certificate
1999-06-01
2001-02-13
Ryznic, John E. (Department: 3745)
Power plants
Pressure fluid source and motor
Pulsator
C060S591000, C091S422000
Reexamination Certificate
active
06185937
ABSTRACT:
The present invention relates to a master cylinder with hydraulic reaction, comprising a working chamber which is filled with a brake fluid and in which there slides, along a first axis, a main piston pierced with an axial bore closed by a reaction piston, the reaction piston also being able to move along the first axis and, within the bore, deliminating a reaction chamber which communicates with the working chamber via a non-return valve and via at least one restriction which together are intended to impose upon a flow of fluid from the working chamber towards the reaction chamber and upon a flow in the opposite direction, first and second respective pressure drops, the first of which is higher than the second.
BACKGROUND OF THE INVENTION
A master cylinder of this type is built into the brake device described in the prior art by EP Patent 0,662,894.
Such a brake device has the advantage that it optimizes the intensity of the braking force in the event of sudden braking, particularly by delaying the rise in the reaction force in reponse to this braking force.
One difficulty has, however, arisen in the optimization of this device in the field of low temperatures, as the viscosity of the brake fluid is then too high to allow a reaction force to occur.
The present invention falls within this context and its object is to provide a master cylinder with hydraulic reaction, the operation of which is not disturbed by variations in the viscosity of the brake fluid, at least in the range of temperatures that a brake device has to cover.
SUMMARY OF THE INVENTION
To this end, the master cylinder of the present invention, which in other respects is in accordance with the generic description given in the above preamble, is essentially characterized in that the non-return valve and the restriction are mounted so that they can move with respect to the main piston.
For example, the non-return valve and the restriction are borne by a third piston sliding in leaktight fashion in the bore between two stops of this bore.
In this case, a spring loaded in compression is preferably placed in the reaction chamber between the reaction piston and the third piston.
According to one possible embodiment of the invention, in which the non-return valve comprises a shut-off member elastically urged against a seat, the restriction simply consists of a leakage between the shut-off member and the seat.
REFERENCES:
patent: 2343901 (1944-03-01), Groves
patent: 4330995 (1982-05-01), Miyakawa et al.
patent: 4884492 (1989-12-01), Maehara
patent: 5735124 (1998-04-01), Cords et al.
Bacardit Juan Simon
Sacristan Fernando
Bosch Sistemas de Frenado S.L
Comstock Warren
McCormick Jr. Lee H
Ryznic John E.
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