US3657971A

US3657971A - Radial piston pumps or motors

Info

Publication number: US3657971A
Application number: US30442A
Authority: US
Inventors: Frank George Freeman
Original assignee: Lucas Industries Ltd
Current assignee: ZF International UK Ltd
Priority date: 1970-04-21
Filing date: 1970-04-21
Publication date: 1972-04-25
Anticipated expiration: 1989-04-25

Abstract

A radial piston pump includes two recesses connected to the high pressure port with one recess arranged in proximity to the rotor face, to provide an axial force to counterbalance the axial force on the rotor from the high pressure port, and the other recess in proximity to the rotor shaft to provide a radial force to counterbalance the radial force from high pressure liquid in the bores in the rotor. The axial force and the radial force form two couples which have equal and opposite moments.

Description

United States Patent Freeman [45 Apr. 25, 1972 [54] RADIAL PISTON PUMPS OR MOTORS 2,458,985 1/1949 Ferris et al ..91/492 3,096,723 7/1963 Puryeak ....9l/485 [72] Invent G l England 2,506,974 5/1950 Sokensen ..91/485, [73] Assignee: Joseph Lucas (Industries) Limited, Biri g England Primary Examiner-William L. Freeh [22] Filed: AP 21 1970 Attorney-Holman & Stern [21] Appl. No.: 30,442 [57] ABSTRACT A radial piston pump includes two recesses connected to the U.S. 4 I v pressure port with one recess arranged in proximity to {he l 1/06 rotor face, to provide an axial force to counterbalance the [58] Field of Search ..9 1/485, 486, 487 axial force n the t m the highpressure port, and the other recess in proximity to the rotor shaft to provide a radial References Cited force to counterbalance the radial force from high pressure UNITED STATES PATENTS liquid in the bores in the rotor. The axial force and the radial v force form two couples whichhave equal and opposite mo- 3,044 .4l2 7/1962 Orshansky ...9l/492 mem 2,827,859 3/1958 Crane ...91/492 2,620,733 12/1952 Overbelle ..91/485 l Clairn 3 Drawing iFigures PATENTEB APR 2 5 I972 SHEET 10F 2 WM 2 1 m,

mvuanoe 01% {M ATTQNEYS RADIAL PISTON PUMPS R MOTORS Thisinvention relates to a radial piston pump or motor of the type comprising a housing, a rotor including a disc portion within the housing and a shaft projecting from the housing, said disc portion being formed witha plurality of radial bores and with transverse passages communicating with said pores respectively and opening on to one face of said disc portion, a plurality of pistons slidable respectively in said bores, a cam in the housing for causing the pistons to reciprocate in said bores as the rotor is rotated, and inlet and outlet ports in'the housing with whichthe passages are successively brought into communication as the rotor is rotated.

In a pump or motor of this type therotor is subjected to a radial force caused by the pressure of fluid in the bores and to an axially directed force offset from the rotary axis and caused by the pressure of liquid in the passagesand in which ever of the ports is at high pressure. These forces cause some difficulty in providing suitablebearings for the rotor andit is an object of the invention to provide a pump or motor-of the kind specified in which the effect of these forces is overcome.

ln accordance'with the invention there is provided a pump or motor of the kind specified in which the housing is formed with first and second recesses in communication with the port which is at high pressure iri'use,s'aid first recess being arrangedso that the fluid therein applies a force to the shaft q is shown in the drawing by. the arrowR" equal and opposite to the radial force applied to the rotor by 1 high pressure fluid in said bores and at a position axially spaced from the rotor, said second recess being arranged so that fluid therein applies to the rotor a force equal and opposite to the force applied thereby by high pressure fluid in'the passages and the port which is at high pressure, at a position diametrically opposite the, port which is at high pressure, the arrangement being such that the moments of the equal and opposite forces applied to the rotor are equal and opposite.

In the accompanying drawings:-

FIG. 1 is a section through oneexample of a pump in accordance with the invention; and

FIGS. 2 and 3 are sections respectively taken on lines 2--2 and3--3ofFlG.1.' i

The pump shown includes a housing 10in three parts 11, 12 and 13. The part 11 comprises a disc portion'lla, a rim portion llb and a boss portion He. The rim portion 11b is coaxial with the disc portion 11a but the boss portionllc is 011- set. The rim portion 11b is formed internally with a cam track 14.

The housing part 12 is formed with an inlet port 15 and an outlet port 16. The outlet port 16 has associated with it a kidmy shaped flat member 17. The housing part 13 forms in combination with the housing part 12 a casing for a centrifugal impeller 18 by means of which fluid is caused to flow from the inlet 19 of the pump to the inlet portlS.

The housing rotatably supports a rotor 20. This rotor consists of a disc portion 21 which lies within the cam track 14, a shaft portion 22 projecting from one face of the disc portion and an auxiliary shaft portion 22a projecting from the other side of the disc portion 21 and supporting the impeller 18. The disc portion 21 is formed with radial bores in which pistons 23 are slidably mounted. Each piston 23 carries at its radially outer end a slipper 24 which engages the cam track 14. The face of the disc portion 21 remote from the shaft portion 22 is formed with passages which can communicate with the outlet port 16 through openings in the member 17. The arrangement is such that, in use, the bores in the disc portion 21 can draw in fluid from the inlet port 15 as the pistons 23 are moving outwardly, which occurs over half of each revolution. Over the and can cause liquid to bedisplaced through the openings in the member 17 and through the outlet port 16. it will appreciated that over the half revolution during which the pistons are moving inwardly there will be .high pressure present in the bores and hence in the passages which communicate with the outlet port 16. Thus there is a radial force applied to the disc portion 21 with its line of action as indicated by the arrow R in Fl G.. 1. Also an axial force is applied to one face of the disc portion 21 with its line of action, indicated by arrow A in FIG. 1 offset from the axis of the rotor by a distance r.

To counteract these out-of-balance forces there are provided within the part 11 of the housing first and second recesses which are connected via drillings 30in thehousing to the high pressure port 16. The first of these recesses, 25, is formed withinthe boss portion 11c so that fluid pressure in the recess 25 acts upon the shaft portion 22. The area and location of the recess 25 are suchthat the force applied to the shaft portion 22 is equal andopposite to the force R. The line of action of the force applied by fluid pressure in the recess 25 and the spacing between the lines of action R and R is a. The other recess 26 is of arcuate form and acts upon the face of the rotor disc 21 opposite thatin which the passages which communicate with the ports 15, 16 are formed. This recess 26 is so disposed and of such dimensions that the pressure of fluid in the recess 26 applies an axial force A (which is equal and opposite to, the' force A) to the rotor at a position offset by distance r' (which is equal to r) from the axis in the opposite direction to the direction r. Thearrangement is such that the'moment aR of a the radial forces is equal and opposite to the moment 2Ar of the axial forces so the rotor'is held in equilibrium. a

Having thus described my invention what I claim as new and desire to secure by Letters Patent is:

l. A radial piston type pump ormotor comprising a housing,

I a rotor including a disc portion within the housing and a shaft other half of the revolution the pistonsare moving inwardly projecting from the housing, said disc portion being formed with a plurality of radial bores and with transversepassages communicating with said bores respectively and opening onto one faceof said disc portion a plurality of pistons slidable respectively in said bores, a cam in the housing operatively related to the pistons to reciprocate the pistons in said bores as the rotor is rotated and high and low pressure ports in the housing into communication with which the passages are successively brought as the rotor is rotated the housing being formed with first and second recesses in communication with the high pressure pot, said first recess being disposed adjacent the shaft at a position axially spaced from the disc portion and has an efi'ective area such that high pressure fluid therein applies a radial force to the shaft equal and opposite to a radial force applied to the rotor by high pressure fluid in said bores said radial forces having parallel lines of action spaced by a first distance from one another, said second recess being disposed adjacent a face of the disc portion opposite that on to which the transverse passages open and having an effective area such that high pressure fluid therein applies to the'disc portion an axial force equal and opposite to an axial force applied thereto by high pressure fluid in the passages and the high pressure port at a position diametrically opposite the high pressure port with respect to axis of the rotor, so that the axial forces have lines of action spaced by a second distance, and the product of the effective area of the first recess and the first distance being equal to the product of the effective area of the second recess and the second distance so that the moments of the equal and opposite forces applied to the rotor are equal and opposite.

i 1 i i 11'

Claims

1. A radial piston type pump or motor comprising a housing, a rotor including a disc portion within the housing and a shaft projecting from the housing, said disc portion being formed with a plurality of radial bores and with transverse passages communicating with said bores respectively and opening onto one face of said disc portion a plurality of pistons slidable respectively in said bores, a cam in the housing operatively related to the pistons to reciprocate the pistons in said bores as the rotor is rotated and high and low pressure ports in the housing into communication with which the passages are successively brought as the rotor is rotated the housing being formed with first and second recesses in communication with the high pressure pot, said first recess being disposed adjacent the shaft at a position axially spaced from the disc portion and has an effective area such that high pressure fluid therein applies a radial force to the shaft equal and opposite to a radial foRce applied to the rotor by high pressure fluid in said bores said radial forces having parallel lines of action spaced by a first distance from one another, said second recess being disposed adjacent a face of the disc portion opposite that on to which the transverse passages open and having an effective area such that high pressure fluid therein applies to the disc portion an axial force equal and opposite to an axial force applied thereto by high pressure fluid in the passages and the high pressure port at a position diametrically opposite the high pressure port with respect to axis of the rotor, so that the axial forces have lines of action spaced by a second distance, and the product of the effective area of the first recess and the first distance being equal to the product of the effective area of the second recess and the second distance so that the moments of the equal and opposite forces applied to the rotor are equal and opposite.