Pumps – With condition responsive pumped fluid control – Pressure responsive relief or bypass valve
Patent
1981-07-07
1983-10-11
Gluck, Richard E.
Pumps
With condition responsive pumped fluid control
Pressure responsive relief or bypass valve
418149, 418259, F04B 4908
Patent
active
044089643
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
1. Technical Field
This invention relates to a vane pump which is suitable to serve as a source of hydraulic fluid pressure for a power steering system of a motor vehicle.
Generally, a vane pump of the type described is driven by an engine mounted on a motor vehicle to delivery a hydraulic fluid under pressure for operating a power cylinder which is adapted to assist the operator of the motor vehicle in manipulating the steering wheel. Such a vane pump is furnished with a flow control valve to supply the power cylinder with a substantially constant amount of pressurized fluid.
2. Background Art
In a vane pump, a flow control valve is located in a position where the suction and delivery ports of the pump are gathered so that the valve may bypass an excessive part of the discharged hydraulic fluid back to the suction port and thereby control the delivery from the pump to a load to a predetermined value.
For this purpose, a side plate is provided to define within a pump housing a high pressure chamber which permits the independent flows of high pressure fluid from two outlet ports of the pump to join each other and advance therefrom to the flow control valve. The two outlet ports are located in symmetrical relation with respect to a drive shaft of the pump.
The side plate is received in a bore of the pump housing while O-rings are employed to seal the outer periphery of the side plate and that portion of the side plate through which the pump shaft extends, respectively.
Together with the side plate, a cam ring is accommodated in the pump housing and covered by a cover plate at the other end thereof.
A rotor having vanes thereon is disposed in the cam ring to be driven by the pump shaft for rotation.
The cam ring whose width is the same as the width of a vane must be held under a moderate pressure between the side plate and cover plate so as to prevent the fluid from leaking at the opposite lateral ends of the vanes with respect to the direction of rotation of the vanes.
To meet this requirement, the side plate is constantly biased by a spring against the cam ring from the high pressure chamber side inside the pump housing. The cam ring is thus held between the spring biased side plate and the cover plate which is bolted to the pump housing.
The prior art vane pump having the above construction involves various problems as will be described. First, an additional number of parts are necessary for the vane pump because the high pressure chamber is defined by the pump housing and side plate.
Second, the pump housing requires intricate machining to haver thereinside the high pessure chamber and the relatively large bore adapted to receive the side plate and cam ring.
Third, a spring must be installed in the vane pump to exert a strong pressure force on the side plate so that the assembly remains liquid-tight particularly at a start of operation of the pump. This spring does not function in any way once the pump starts its operation because the high fluid pressure which will build up thereafter can be utilized for the same function.
It is an object of the present invention to provide a vane pump which is small in the number of necessary parts, compact in design and economical to produce.
It is another object of the present invention to provide a vane pump which achieves improved machinability by making the bore inside the pump housing needless.
DISCLOSURE OF INVENTION
According to the invention, either a pump housing or a cover plate is formed with a high pressure chamber by casting with a core. That end of the pump housing or of the cover plate formed with the high pressure chamber constitutes a surface with which a rotor and vanes carried thereon are directly and slidably engaged. Outlet or inlet ports are formed on said specific slide surface of the pump housing or of the cover plate. This makes the construction simple and therefore cuts down the production cost due to the omission of various component parts such as the side plate, spring and oil seals.
A cam ring is placed between the pump housi
REFERENCES:
patent: 2856861 (1958-10-01), Adams et al.
patent: 2910944 (1959-11-01), Pettibone
patent: 3645647 (1972-02-01), Ciampa et al.
Kugimiya Fusayoshi
Mochizuki Norihiro
Gluck Richard E.
Kayaba Kogyo Kabushiki-Kaisha
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