Power plants – Pressure fluid source and motor – Pulsator
Patent
1992-07-22
1994-02-08
Look, Edward K.
Power plants
Pressure fluid source and motor
Pulsator
60585, 60592, 91376R, F15B 700, B60T 1126
Patent
active
052840174
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a hydraulic master cylinder particularly, but not exclusively, for use in a clutch control system of a motor vehicle. In particular the invention is concerned with a master cylinder which includes a reservoir in which a flexible diaphragm is provided which separates fluid in the reservoir from ambient air. Such an arrangement is disclosed in U.S. Pat. No. 4,407,125 where the master cylinder is used in a clutch release system which is filled with hydraulic fluid and bled before being shipped and installed on the motor vehicle. Other master cylinders having reservoirs containing flexible diaphragms are disclosed in U.S. Pat. No. 4,590,765 and U.S. Pat. No. 3,357,181.
It is becoming of increasing importance to reduce the size of components such as hydraulic master cylinders so as to take up the minimum amount of space in the engine compartment of the vehicle. In each of the master cylinders referred to above the reservoir is tubular with its axis projecting radially outwards from the remainder of the cylinder. Whilst there are many instances where such an arrangement is perfectly acceptable, such radially projecting reservoirs can prove difficult to accommodate in certain cases. Documents GB-A-1536353 and DE-A-3246130 illustrated the known use of annular fluid feeding spaces around a master cylinder bore. However such fluid spaces do not constitute fluid reservoirs in that they are themselves connected to fluid reservoirs that project from the master cylinder.
An object of the present invention is to provide a master cylinder including a reservoir which provides improved compactness whilst permitting use in a pre-filled system.
According to the invention there is provided a hydraulic master cylinder comprising a body formed with a bore, a piston slidable in the bore to discharge hydraulic working fluid from the bore, and a reservoir whose fluid chamber is arranged to communicate with the pressure chamber of the bore when the piston is in an `at-rest` condition, the reservoir containing a flexible diaphragm which separates fluid in the reservoir from ambient air, characterised in that the reservoir extends concentrically around the bore, and the diaphragm projects into the reservoir. The or each locating portion may be a thickened portion of its associated wall.
Preferably the reservoir extends from one end of the body. Such an arrangement facilitates easy manufacture of the body as the reservoir can easily be formed with an open axial end into which the diaphragm can be inserted.
The diaphragm may include a portion extending between the inner wall of the diaphragm and overlying the end of the bore.
Conveniently, the reservoir may be sealingly closed by a cap at one end of the body and, in such a case, the cap may hold a mounting portion of said diaphragm in sealing engagment with a mounting on the body to inhibit leakage of ambient air into the reservoir.
The reservoir may be provided around one end of the bore with an operating rod for the piston extending out of the opposite end of the bore. The piston, in such a case, will preferably be urged along the bore by pulling the operating rod, e.g., by means of a clutch pedal.
Preferably the hollow interior of the piston is sealed from said reservoir by means of a closure element. The operating rod may be retained in the piston by the closure element and a surface of the piston. The said surface of the piston and an interengaging surface of the operating rod may be of complementary shape, e.g., of spherical form. The complementary shape is preferably arranged to permit a certain mount of angular tilting of the operating rod relative to the piston.
A master cylinder in accordance with the invention will now be described by way of example with reference to the accompanying drawings in which:
FIG. 1 is a cross-section through a master cylinder in accordance with the invention for a clutch control system with a piston in a rest position,
FIG. 2 is a cross section similar to FIG. 1 showing the piston in a working position.
FIG. 3 is a cross-se
REFERENCES:
patent: 1963114 (1934-06-01), Bowen
patent: 1981653 (1934-11-01), Loweke
patent: 3065604 (1962-11-01), Radol
patent: 4407125 (1983-10-01), Parsons
patent: 4941323 (1990-07-01), Leigh-Monstevens
Automotive Products plc
Germain Lee A.
Look Edward K.
Milliken Paul E.
Nguyen Hoang
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