Power plants – Pressure fluid source and motor – Pulsator
Patent
1996-09-13
1999-03-09
Lopez, F. Daniel
Power plants
Pressure fluid source and motor
Pulsator
92 51, 92 52, 92 60, F15B 710
Patent
active
058785787
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a hydraulic pressure generator comprising a body having a first blind cylindrical bore formed therein within which slides longitudinally a piston assembly driven by an actuating rod and bearing a seal member which defines, within the first bore, a pressure chamber provided with a pressure outlet, the piston assembly comprising a cylinder having a closed end which is connected to the actuating rod and in which is formed a second bore which is open on the pressure chamber side, an auxiliary piston sliding in the second bore and defining therein a compensation chamber of variable volume which encloses a deformable member adapted to exert an elastic force between the auxiliary piston and the closed end of the cylinder.
BACKGROUND OF THE INVENTION
A device of this kind is described for example in European Pateint EP-0 318 629, which relates to a pressure generator which is suitable in particular for the hydraulic actuation of the clutches of automobile vehicles.
When a hydraulic pressure generator is used as a master cylinder for the clutch of an automobile vehicle, the axial vibration of the drive shaft, connected to the clutch assembly, gives rise to mechanics and hydraulics vibrations which are transmitted through the clutch slave cylinder to the master cylinder and consequently to the pedal, producing a disagreeable sensation for the driver.
Although the patent cited above specifically has as an object to propose means for reducing these vibrations, and even though the device described in this patent does indeed have significant qualities from this point of view, the characteristic curve of the output pressure produced by the device against the displacement of the piston assembly has a region of non linearity which is undesirable in certain particular circumstances.
SUMMARY OF THE INVENTION
The present invention is placed in this context and has as an object to provide a hydraulic pressure generator in which the mechanics and hydraulics variations are damped efficiently, but whose characteristic curve exhibits greater linearity.
To this end, a hydraulic pressure generator according to the present invention is essentially characterized in that the compensation chamber communicates with the pressure chamber through a restriction formed in a longitudinal duct in the auxiliary piston, in that a first portion of the auxiliary piston remains outside the second bore, and in that the sealing member is borne by the first portion of the auxiliary piston.
According to a preferred embodiment of the invention, the deformable member comprises a sleeve of elastomeric material, having a longitudinal passage positioned facing the duct formed in the auxiliary piston.
BRIEF DESCRIPTION OF THE DRAWINGS
Other features and advantages of the invention will appear clearly from the following description thereof, given by way of non limitative example, with reference to the single figure of the accompanying drawings, which is a sectional view of a pressure generator in accordance with the invention.
DETAILED DESCRIPTION OF THE DRAWING
As shown in the drawing this pressure generator comprises essentially a body 1, and a piston assembly 2, the piston assembly being driven by an actuating rod 3, and itself consisting of a cylinder 21 and an auxiliary piston 22.
The piston assembly 2 slides longitudinally in a first blind cylindrical bore 11 formed in the body 1, and bears a sealing member 4 which defines, within this first bore 11, a pressure chamber 12 provided with a pressure outlet 13.
The cylinder 21 has a closed end 210 which is connected to the actuating rod 3.
In addition, the cylinder 21 is formed with a second bore 211 which is open on the side of the pressure chamber 12 and within which slides the auxiliary piston 22.
The auxiliary piston 22 defines, within the second bore 211, a compensation chamber 23 of variable volume, which encloses a deformable member 5 adapted to exert an elastic force between the auxiliary piston 22 and the closed end 210 of the cylinder 21.
In accordance w
REFERENCES:
patent: 3955371 (1976-05-01), Bueler
Comstock Warren
Lopez F. Daniel
McCormick Jr. Leo H.
Robert Bosch Sistemi Frenanti Spa
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