Power plants – Pressure fluid source and motor – Pulsator
Patent
1998-02-17
1999-11-23
Nguyen, Hoang
Power plants
Pressure fluid source and motor
Pulsator
60533, B60T 702
Patent
active
059878878
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention concerns a master cylinder for a hydraulic friction clutch or brake of a motor vehicle, said master cylinder being connected to a physically actuatable pedal by a piston rod which is articulated in retainer shells enclosed in a piston skirt bushing, an end of said piston skirt bushing remote from the piston rod being connected to a piston which is longitudinally displaceable in a guide sleeve of the master cylinder, an end face of said piston delimiting a pressure chamber which at the same time serves as a seal carrier.
BACKGROUND OF THE INVENTION
A master cylinder of the generic type known from DE-OS 42 12 107 comprises a piston composed substantially of a piston head and a piston skirt bushing. To form a structural unit, a centrally arranged, integrally formed piston neck of the piston is positively fixed in the piston skirt bushing. To obtain a positive locking of the piston skirt bushing on the piston neck, a radially inwards directed rim on the end of the piston skirt bushing engages a peripheral groove of the piston neck. The end of the piston neck facing the piston rod comprises a spherical depression on which the piston rod ball is supported. The piston rod ball is retained in the piston skirt bushing by two spherical semi-shells which partially enclose the piston rod ball and comprise projections whose ends form radially inwards directed sections which engage a groove of the piston neck and thus assure a positive locking. Further, the piston skirt bushing is longitudinally displaceable in a guide sleeve of the master cylinder. This prior art configuration of a master cylinder requires a special sealing of the piston neck in the piston skirt bushing and a very high technical production quality of the spherical semi-shells which together with the spherical depression on the end of the piston neck assure a positive retention of the piston rod ball. In addition, the assembly of the prior art master cylinder is very complicated and therefore results in high manufacturing costs.
OBJECT OF THE INVENTION
It is the object of the invention to provide a configuration of a master cylinder with the properties of improved functional reliability, simple assembly, design space optimization and economy.
SUMMARY OF THE INVENTION
The master cylinder (1) of the invention for a hydraulic friction clutch or brake of a motor vehicle, said mater cylinder (1) being connected to a physically actuatable pedal by a piston rod (17) which is articulated in retainer shells (14) enclosed in a piston skirt bushing (10), an end of said piston skirt bushing (10) remote from the piston rod (17) being connected to a piston (7) which is longitudinally displaceable in a guide sleeve (6) of the master cylinder (1), an end face of said piston (7) delimiting a pressure chamber (8) which at the same time serves as a seal carrier is characterized in that the retainer shells (14) which fill an inner space of the piston skirt busing (10) without play and, on their ends nearer the piston rod (17) comprise a cup-shaped recess (15) in which a ball head (16) of the piston rod (17) is retained solely by positive locking, the piston skirt bushing (10) forming a structural unit with the radially stepped piston (7) which is positively locked on a closed bottom (11) of the piston skirt bushing (10).
The articulation of the piston rod in the piston of the master cylinder is achieved by semi-shells which fill the inner space of the piston skirt bushing without play and, on their ends nearer the piston rod, comprise a cup-shaped recess each in which the ball head of the piston rod is retained solely by positive locking. In contrast to the prior art master cylinder, the semi-shells of the invention serve both to retain the ball head and to directly support and transmit the force exerted by the clutch pedal on the piston of the master cylinder. The piston is assembled from its individual parts as follows: the ball head of the piston rod is first placed in the cup-shaped recesses of the retainer shells before t
REFERENCES:
patent: 2349345 (1944-05-01), Goepfrich
patent: 4109899 (1978-08-01), Takatsu
patent: 4372118 (1983-02-01), Andresen
patent: 4831916 (1989-05-01), Leigh-Monstevens et al.
patent: 5284017 (1994-02-01), Kopacin
Adler Dieter
Prosch Gerhard
Schaaf Peter
Sperner Christian
LuK GmbH & Co.
Nguyen Hoang
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