US3564976A

US3564976A - Radial piston type hydraulic motor

Info

Publication number: US3564976A
Application number: US813903A
Authority: US
Inventors: Arthur Frederick Allen
Original assignee: Rolls Royce Motor Cars Ltd
Current assignee: Bentley Motors Ltd
Priority date: 1968-04-05
Filing date: 1969-04-07
Publication date: 1971-02-23
Anticipated expiration: 1988-02-23
Also published as: GB1217525A

Abstract

A radial-piston type hydraulic motor having a cylinder housing with at least two rows of cylinder bores with pistons in each bore, the cylinder housing being provided with a central axially extending fluid flow and return passage and interconnected fluid passages communicating with the central passage and arranged to permit substantially simultaneous flow of fluid to and from the at least two rows of cylinder bores. A valve member provided in said central passage and axially movable is arranged to control the flow and return of fluid to the at least two rows of cylinder bores.

Description

United States Patent inventor Arthur Frederick Allen Littleover, Derby, England Appl. No. 813,903

Filed Apr. 7, 1969 Patented Feb. 23, 1971 Assignee Rolls-Royce Limited Derby, England Priority Apr. 5, 1968 Great Britain 1638 l/ 68 RADIAL PISTON TYPE HYDRAULIC MOTOR 8 Claims, 4 Drawing Figs.

U.S. Cl 91/492,

91/180 lnt.Cl...., F0ll33/02 Field of Search 91/205,

204; 9l/l80, (cards); 103/161 (Cursory) [56] References Cited UNITED STATES PATENTS 1,488,528 4/1924 Cardini 91/180 2,303,685 12/1942 Eden et al..... 91/205 2,811,143 10/1957 Baines etal 91/180 2,989,005 6/1961 Gardineer,.lr... 91/205 3,081,708 3/1963 Nyman et a1 91/205 Primary Examiner- Paul E. Maslousky Attorney-Cushman, Darby and Cushman ABSTRACT: A radial-piston type hydraulic motor having a cylinder housing with at least two rows of cylinder bores with pistons in each bore, the cylinder housing being provided with a central axially extending fluid flow and return passage and interconnected fluid passages communicating with the central passage and arranged to permit substantially simultaneous flow of fluid to and from the at least two rows of cylinder bores. A valve member provided in said central passage and axially movable is arranged to control the flow and return of fluid to the at least two rows of cylinder bores.

PATENTEU FEB23 191:

SHEET 2 [IF 2 RADIAL PISTON TYPE HYDRAULIC MOTOR smaller total package volume may be achieved by using a suitable number of small ball pistons in preference to a less number of large ball pistons.

The present invention relates to a construction of motor in which a relatively small size and weight for a motor power output can be achieved.

According to the present invention a radial piston type hydraulic motor comprises a cylinder housing, two rows of cylinder bores in said housing, and interconnecting fluid passages adapted to permit substantially simultaneous flow of fluid to and from said two rows.

Preferably said rows comprise axially spaced rows of equiangularly spaced apart bores, the bores of one row being angularly displaced with reference to the bores of the other row by half the angular spacing of adjacent bores of each row. The axial spacing of the rows may be such that the bores of the two rows are at least partly interdigitated.

In this way the axial length of the motor may be considerably reduced.

There is preferably a central axially extending fluid flow and return passage, said interconnecting passages communicating with said central passage. In this case there is preferably a valve member axially movable in said central passage and adapted to control flow and return of fluid to said rows of bores.

The invention is particularly applicable to a motor in which there are a plurality of said pairs of rows, and control valve means adapted to bring a variably number of said pairs of rows into operation. Said control valve may well comprise said axial movable valve member.

The interconnected fluid passages may be formed integrally in said housing, or alternatively they may be formed in the outer surface of a cylindrical insert which fits inside said housing.

The invention will now be particularly described merely by way of example with reference to the accompanying drawings in which:

FIG. 1 is an axial cross section through an hydraulic motor according to the present invention.

FIG 2 is a view of the cylinder housing of the motor of FIG 1 taken in the direction of arrow A,

FIG 3 is a transverse section on the line 3-3 of FIG 1, and

FIG 4 is a transverse section on the line 4-4 of FIG 1.

Referring first to FIG 1 an hydraulic motor comprises a cylinder housing 10 of substantially annular form having formed therein six rows 11 to I6 of cylinder bores 17, each row comprising six angularly spaced apart cylindrical bores disposed in the same transverse plane. In each of these bores 17 there is accommodated a tight fitting ball piston 18.

Concentrically surrounding the housing 10 there is an annular member 19 rotatable with respect to the housing 10 and mounted therefrom in bearings 20. In this particular instance the housing 10 is stationary while the member 19 may rotate.

The member 19 carries on its inner periphery a series of cam tracks 21 to 26, each of which cooperates with the ball pistons 18 of a respective one of the rows 11 to 16. The cam tracks are so shaped, as is best seen from FIGS. 3 and 4, that by forcing the ball pistons 18 to move radially within their bores 17 in a particular pattern, rotation of the member 19 may be effected.

High pressure fluid may be fed to and vented from the space within the bores 17 radially inward of the ball pistons 18 so as to enable the ball pistons to be forced out against, and allowed to retract from the respective cam track. In order to effect this supply and return, each bore is connected by way of ducting to a central passage 27. Closely fitting within this central passage there is an axially movable valve member 28 which comprises an entrance hole 29 adapted to allow pressure fluid to flow from a feed port 30 in the housing 10 to a central bore 3] within the valve member and then to supply ports 32 and 33 which allow the high pressure fluid to escape from the central bore 31 through the wall of the valve member. The outer surface of the valve member 28 is provided with axially extending grooves one of which is shown at 34 which connect with a fluid return-passage 35 in the housing 10.

The valve member 28 is splined at one extremity 40 to the member 19, and therefore rotates with this member. The return grooves such as 34 and the flow passages such as 32 and 33 are arranged alternately around the periphery of the valve member 38 as can best be seen in sections of FIGS. 3 and 4.

Each of the rows of bores 17 is provided with a series of passages to permit flow and return of pressure fluid as permitted by the valve member 28. Thus the row 11 is provided with passages which are partly visible at 36 which interconnect each one of the bores 17 of this row with a corresponding bore of the next adjacent row 12. This interconnection is indicated by arrows on FIG 2. Similarly the remaining pairs of rows 13 and l4: l5 and 16 are similarly interconnected.

Communicating with the interconnecting passages 36 there are a plurality of feed parts or passages 37 which interconnect these passages with selected points on the periphery of the central channel 27. The ports 37 are angularly spaced apart around the periphery of the channel 27. It will, therefore, be appreciated that because of the angular spacing of the flow and return passages in the valve member 28 and the angular spacing of the passages 37 which communicate with the spaces radially inwards of the ball pistons, it can be arranged that the ball pistons are forced outwardly by the pressure fluid when they come adjacent a selected part of the respective cam track, and correspondingly the space may be vented so as to allow the pistons to retract when they are adjacent another selected part of the cam track.

Axial movement of the valve member 28 is sufficient to enable either one, two or three pairs of rows of pistons to be supplied with pressurized fluid. Thus it will be seen in FIG 1 that I by moving the valve member slightly to the left, the extreme right-hand pair of pistons will cease to be supplied with pressure fluid; by moving the valve member to its extreme lefthand position only the extreme left-hand pair of rows will be supplied with pressure fluid. In this way the motor is given in effect a variable gear box action in that when large torque and low speed is required all the rows can be energized and as the torque drops off and the speed increases the number of rows can be correspondingly reduced.

It will be appreciated that the length of valve travel required for the valve member 28 is considerably effected by the spacings of the various feed ports of which 37 are examples. If it is required to avoid the drilling of complicated passages within the housing 10 then the arrangement according to the present invention in which adjacent rows are interconnected by the passages 36 provides a considerably reduced axial spacing of the various feed passages and therefore enables a considerable reduction in the required travel of the valve. Even if it is not required to have a variable number of rows in use the interconnected arrangement could still have advantages, however, the advantage of this system is more pronounced when there are a large number of rows and a large amount of variation in the number of rows is required.

As can be seen in FIG 2 the individual bores of adjacent rows are angularly staggered by half the angular spacing between adjacent bores so that each bore is in line with the space between two bores of the next adjacent row. This enables the bores to be interdigitated to some extent and hence enables the axial length of the motor to be considerably reduced without weakening the cylinder housing 10.

This point is again illustrated by comparison of FIGS. 3 and 4 which are sections through adjacent rows of bores and pistons. It will be noted that whereas the row in FIG 3 has a piston and cylinder at the top and bottom of the section, in the case of FIG 4 these positions correspond with an inter bore spacing. This, therefore, enables the bores to be axially spaced apart by a distance which would involve contiguity of the bores of adjacent rows were they not angularly staggered.

lclaim:

l. A radial piston type hydraulic motor comprising: a cylinder housing, at least two rows of cylinder bores in said housing, a central axially extending fluid flow and return passage positioned in said housing, interconnecting fluid passages communicating with said central passage and arranged to permit substantially simultaneous flow of fluid to and from cylinder bores of said at least two rows of bores, and a valve member axially movable in said central passage and arranged to control flow and return of fluid to the bores of said at least two rows of bores.

2. An hydraulic motor as claimed in claim 13 and in which said rows comprise axially spaced rows of equiangularly spaced apart bores, the bores of one row being angularly displaced with reference to the bores of an adjacent row by half the angular spacing of adjacent bores of each row.

3. An hydraulic motor as claimed in claim 2 and in which the axial spacing of the rows is such that the bores of adjacent rows are at least partly interdigitated.

4. An hydraulic motor as claimed in claim 1 and in which said valve member is arranged to bring a variable number of said rows into operation.

5. An hydraulic motor as claimed in claim 1 and comprising a spherical piston closely fitting in each said bore.

6. An hydraulic motor as claimed in claim 5 and in whicl' there is an annular member surrounding said housing and having on its inner surface a plurality of cam tracks, each track being adapted to cooperate with the pistons of one row of the bores to tend to produce relative rotational movement between the housing and the annular member.

7. An hydraulic motor as claimed in claim 6 and in which said housing is fixed and said annular member is arranged to rotate about the housing.

8. An hydraulic motor as claimed in claim 1 and in which said housing is formed to produce said interconnecting passages.

Claims

1. A radial piston type hydraulic motor comprising: a cylinder housing, at least two rows of cylinder bores in said housing, a central axially extending fluid flow and return passage positioned in said housing, interconnecting fluid passages communicating with said central passage and arranged to permit substantially simultaneous flow of fluid to and from cylinder bores of said at least two rows of bores, and a valve member axially movable in said central passage and arranged to control flow and return of fluid to the bores of said at least two rows of bores.

6. An hydraulic motor as claimed in claim 5 and in which there is an annular member surrounding said housing and having on its inner surface a plurality of cam tracks, each track being adapted to cooperate with the pistons of one row of the bores to tend to produce relative rotational movement between the housing and the annular member.