Motors: expansible chamber type – Three or more cylinders arranged in parallel radial or... – Motive fluid supply or discharge through piston
Patent
1980-11-21
1982-11-02
Freeh, William L.
Motors: expansible chamber type
Three or more cylinders arranged in parallel radial or...
Motive fluid supply or discharge through piston
91491, 91492, 91488, F01B 1306
Patent
active
043567614
DESCRIPTION:
BRIEF SUMMARY
This invention relates to fluid pressure machines, specifically pumps and motors of the type having a number of cylinders arranged radially in a cylinder block which is mounted for orbital non-rotational movement within a housing. In such machines each cylinder contains a sliding piston which makes sliding contact with an abutment face within the housing. The cylinder block is supported on an eccentric journal carried by a rotatable shaft which is provided with internal ducts for conducting working fluid to and from each cylinder in sequence. In use of such a machine as a motor the successive pressurisation of each cylinder results in orbital motion of the cylinder block, which in turn produces rotation of the shaft, while in use of such a machine as a pump, the rotation of the shaft causes orbital motion of the cylinder block which results in a delivery of fluid under pressure from the cylinders sequentially in each rotation of the shaft.
In known fluid pressure machines of the aforesaid type various means have been proposed to vary the effective swept volume in each cylinder, and hence the relationship between the speed of rotation of the shaft and the fluid flow throughput of the machine, and the relationship between the pressure of the fluid and the torque in the shaft. One such means for varying the effective swept volume of each cylinder is to provide two coaxial pistons in each cylinder, one piston being slidable within the other so that the two pistons define separate working chambers within each respective cylinder. By selectively restraining the outer piston relative to the inner piston the total working volume within each cylinder can be varied, but in general such an arrangement is capable of only two different speeds or torques, namely that resulting from the operation of both pistons in tandem and that resulting from operation of the inner piston only.
An object of the present invention is to provide a fluid pressure machine of essentially simple construction which is capable of providing three alternative working speeds or torques selectively.
A fluid pressure machine according to the invention comprises a number of cylinders arranged radially in a cylinder block which is mounted for orbital nonrotational movement within a housing, pistons which are slidable within the cylinders and in sliding contact with abutment faces within the housing, and a rotatable shaft having an eccentric upon which the cylinder block is journalled, wherein each piston has a cylindrical axial bore, open at its radially inner end, in which a fluid displacing member, fixed relative to the cylinder block, is located, so that the piston defines within the cylinder an annular outer chamber between the cylinder wall and the displacing member, and an inner chamber within the piston bore and including selectively operable valve means for supplying fluid under pressure to the inner and/or the outer chamber to control the operating speed or torque of the machine.
The machine of the present invention is capable of three different working speeds or torques, selectable by operation of the valve means, corresponding respectively to three working conditions in which fluid pressure is supplied to (a) both the inner and outer chambers of each cylinder, (b) the inner chamber only of each cylinder and (c) the outer chamber only of each cylinder. Under all operating conditions the pistons remain in sliding contact with the abutment faces of the housing. Conveniently, therefore, advantage may be taken of hydrostatic balancing of the pistons by providing recesses in the surfaces of the pistons which contact the abutment faces, these recesses being supplied with fluid under pressure through ducts communicating with the inner and/or the outer chamber of the associated cylinder.
Preferably each fluid displacing member is coaxial with the associated cylinder and has a bore, coaxial with the cylinder, which communicates at its radially outer end with the bore of the respective piston and which opens at its radially inner end into a cylindric
REFERENCES:
patent: 879512 (1908-02-01), Braunwalder
patent: 883430 (1908-03-01), Smith et al.
patent: 3296937 (1967-01-01), Guinet
patent: 4318336 (1982-03-01), Bock
Cameron-Johnson Alan
Miles Michael J.
Freeh William L.
Sauer United Kingdom Limited
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