Pumps – Expansible chamber type – Plural pumping chambers
Patent
1996-05-01
1998-12-15
Freay, Charles G.
Pumps
Expansible chamber type
Plural pumping chambers
417273, 921711, F04B 700
Patent
active
058488790
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a hydraulic pump of the kind which includes a pump housing block which is provided with means for driving a piston axially forwards and backwards, a piston-receiving cylindrical bore, inlet and outlet passageways which connect with the cylinder and through which hydraulic fluid is drawn by suction into the cylinder and discharged therefrom respectively, wherein each of the passageways includes a respective check valve which determines the direction in which hydraulic medium will flow in respective passageways.
2. Description of the Related Art
Hydraulic piston pumps are subjected to wear on surfaces which move relative to one another, particularly on the piston and the surfaces of the cylinder bore in which it moves. Such wear is accentuated when the components move at a relatively high speed, and when the pump works at high pressures and is kept working for long periods of time.
The operational efficiency of hydraulic pumps which are subjected to such heavy loads as those inferred above will be gradually impaired or the pump will malfunction, which means, in turn, that the pump must be replaced or repaired. However, the pump normally comprises only one part of a working machine, which must be taken out of operation while the faulty hydraulic pump is being dealt with.
In the case of known radial piston pumps, which are used as hydraulic pumps, a number of pump devices are disposed radially around a pump housing block in a star-like configuration, said block including a drive shaft which is common to the pump devices and which includes an eccentric which coacts with said devices. When such a radial piston pump is in need of repair, it is necessary for an operator or fitter to dismantle each of the pump devices from the block, wherein bolts must be loosened, replaced and re-tightened, and a relatively large working space is required around the pump itself to enable the replacement of pump devices in the pump housing block of the machine in which the hydraulic pump is fitted.
Prior publication DE-A-2,317,089 discloses a paint spray which includes a paint conduit having incorporated therein at least one check valve, to form a paint pump chamber of which one wall consists of a diaphragm which is driven reciprocatingly by pulsating hydraulic pressure generated by a piston which is reciprocatingly movable in a cylinder lining that can be fitted loosely in a bore. It is necessary to dismantle the paint pump chamber before access can be had to the cylinder lining. The bore which receives the lining opens into the hydraulic reservoir at a level beneath the surface of the hydraulic fluid.
Prior publications GB-A-1,302,163 and U.S. Pat. No. 4,968,220 relate to hydraulic pumps where the pump must be dismantled before the cylinder lining/piston can be changed, this work being relatively complicated.
Consequently, no hydraulic pump can be repaired on site in practice and it is therefore necessary in practice to take the whole of the assembly which includes the hydraulic pump to a workshop, in order to repair the pump.
SUMMARY OF THE INVENTION
Accordingly, one object of the present invention is to provide a hydraulic pump construction which will enable the pump to be repaired quickly and simply within the confines of a relatively small space and with the use of a relatively small number of tools.
This object is achieved with the inventive hydraulic pump.
One essential feature of the invention is that the pump housing block has a cylinder which opens out onto the outside of the block, and that a cylinder lining can be inserted loosely into the cylinder and supported against the cylinder wall. A releasable latching device, such as a groove-seated locking ring, is fitted to prevent the lining moving out of the cylinder in a direction towards the outer side of the block. The lining has at least one opening which passes through its cylinder wall and establishes communication between the hollow interior of the cylinder lining and hydrauli
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patent: 4889039 (1989-12-01), Miller
patent: 4968220 (1990-11-01), Filippi et al.
patent: 5107680 (1992-04-01), Hojnacki et al.
Freay Charles G.
Pressmaster Tool AB
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