US3690789A

US3690789A - Hydraulic apparatus

Info

Publication number: US3690789A
Application number: US33717A
Authority: US
Inventors: Peter Spence
Original assignee: Dowty Technical Developments Ltd
Current assignee: Dowty Technical Developments Ltd
Priority date: 1970-05-01
Filing date: 1970-05-01
Publication date: 1972-09-12
Anticipated expiration: 1989-09-12

Abstract

A swash plate pump or motor comprising a rotary cylinder block having cylinders either parallel to or inclined to the rotation axis, a valve on which the block is arranged to rotate, an inclined or inclinable swash plate located adjacent to one end of the cylinder block engageable by cylinders either directly or through the medium of slippers whereby the pistons are reciprocated as the block rotates, a casing enclosing the valve cylinder block and swash plate, the end portion of the cylinder block adjacent to the swash plate having a cylindrical journal bearing surface engaging within a complementary cylindrical bearing surface within the casing to divide the casing into two chambers and passages extending through the cylinder block in close proximity to the cylindrical bearing surfaces and connecting the two chambers for the flow of liquid therethrough during operation of the pump or motor.

Description

United States Patent 1 89 Spence [451 Sept. 12, 1972 [54] HYDRAULIC APPARATUS 3,085,514 4/1963 Budzich ..4l7/203 72 Inventor: Peter s n L kh t E 3,096,723 7/1963 Puryear ..9l/485 1 gland 3,306,209 2/1967 Tyler ..91/472 [73] Assignee: Dpwty Technical Developments P i E i -Willi L, F h

Limited Anorney-Young&Thompson [22] Filed: May 1, 1970 ABSTRACT [21] Appl.No.: 33,717'

A swash plate pump or motor comprising a rotary Related US. Application Data cylinder block having cylinders either parallel to or inclined to the rotation axis, a valve on which the [62] 251 1 2 9 1967 block is arranged to rotate, an inclined or inclinable swash plate located adjacent to one end of the cylinder block engageable by cylinders either directly it??? or through the medium of Slippers whereby the pistons [58] i 7/201 2o3 are reciprocated as the block rotates, a casing enclos- 485 499 ing the valve cylinder block and swash plate, the end portion of the cylinder block adjacent to the swash [56] Referemes Cited plate having a cylindrical journal bearing surface en gaging within a complementary cylindrical bearing UNITED STATES PATENTS surface within the casing to divide the easing into two chambers and passages extending through the cylinder 2,847,984 8/1958 Gallant ..9l/486 block in close proximity to the cylindrical bearing Sup 3,208,395 9/1965 Budzrch ..9l/505 faces and connecting the two chambers for the flow of k lf -l-i liquid therethrough during operation of the pump or oc we t 2,543,624 2/1951 Gabriel ..91/499 2,733,666 2/1956 Poulos ..9l/499 5 Claims, 1 Drawing Figure PATENTED 12 3.690.789

INVENTOR PETE? 5 1 54/0: BY

ATTORNEYS 1 HYDRAULIC APPARATUS This is a division of applicationSer. No. 690,369 filed Dec. 8, 1967 now U.S. Pat. No. 3,612,725.

FIELD OF THE INVENTION 'A reciprocating piston pump or motor having multiple pistons located in cylinders in a rotary cylinder block, the cylinders being either parallel to or inclined to the rotation axis.

Q DESCRIPTION OF PRIOR ART In a swash plate device it is known to mount the rotary cylinder block on a valve surface and to provide a cylindrical bearing around the cylinder blockto locate it for rotation.

SUB/[MARY OF THE INVENTION In accordance with the present invention a swash plate device comprises a rotary cylinder block having cylinders disposed parallel to or inclined to the rotation axis, valve means co-operating with the cylinder block during rotation to connect the cylinders to a fixed high pressure port cyclically during rotation of the cylinder block, a swash plate adjacent one end of the cylinder block, pistons in the cylinders co-operating with the swash plate whereby the pistons will reciprocate during cylinder block rotation, a casing enclosing the cylinder block and swash plate, the end portion of the cylinder block adjacent the swash plate having a cylindrical journal bearing surface engaging within a complementary cylindrical bearing surface within the casing to divide the casing into two chambers, and passages extending through the cylinder block in close proximity to the cylindrical bearing surfaces and connecting the two chambers for the flow of liquid therethrough during operation of the device.

The invention provides cooling for the bearing surfaces by virtue of liquid flow through the passages.

Liquid within the casing preferably flows from the chamber including the swash plate to thechamber enclosing the periphery of the cylinder block.

BRIEF DESCRIPTION OF THE DRAWING One embodiment of the invention will be described with reference to the accompanying cross-sectional drawing.

DESCRIPTION OF THE PREFERRED EMBODIMENT In this drawing the casing 1 is conveniently secured by bolt or other means to a valve block 2. The casing surrounds a rotary cylinder block 3 which is mounted for rotation by means of a large diameter plain bearing 4 which comprises a cylindrical journal bearing surface formed around the cylinder block engaging in a complementary cylindrical bearing surface formed within the casing. The bearing 4 and the cylinder block 3 divide the casing into two

chambers

28 and 40. The location of the bearing 4 is at the end of the cylinder block remote from the valve block 2. Within the cylinder block 3 a number of cylinders 5 are provided each parallel to the axis of block rotation and equally spaced around the rotation axis. In the illustrated embodiment there are five cylinders but in practice any number tains a piston 6 and spring 7 which acts on the piston to urge it outwardly from the cylinder. The surface 8 of the cylinder block is a plane surface set at right angles to the block rotation axis and it includes a port 9 for each of the cylinders 5. The surface 8 co-operates with a flat surface 10 of a valve plate 11 mounted on the valve block 2. The valve plate 11 includes a pair of kidney shaped ports 12 and 13 with which the cylinder ports 9 co-operate during cylinder block rotation. The port 12 is the inlet port and the port 13 is the pressure delivery port. Port 13 is connected within the valve block 2 to a screw connection 14 by which pressure liquid leaves the pump. The port 12 is formed by a cut away portion of the valve plate extending inwardly from its periphery, this cut away portion being located over a recess 30 in the valve block which opens to the interior of the casing 1. The valve plate 11 may be retained in its operative position by a plurality of dowel pins 20.

The inlet 15 for the pump is formed in the casing at the end thereof remote from the valve block 2. This may be a screw connection or the whole end of the casing may be open where the pump is intended for operation submerged in liquid in a reservoir.

The casing 1 also surrounds a swash plate 16 which is mounted on suitable trunnions for adjustment about an axis 17 which extends perpendicularly to the plane of the drawing. Angular adjustment of the swash plate may be efi'ected by any conventional means. The swash plate 16 has a plane swash surface 18 facing the cylinder block. A slipper 19 is fitted by a ball joint 38 to the end of each piston 6 for engagement with the swash surface 18. The slippers 19 may be fed with hydraulic liquid in conventional manner from the associated cylinders in order to provide a hydrostatic bearing between the slipper and the swash surface. Within a central bore 21 in the cylinder block a spring 22 is located which presses outwardly through a ball 23 on to a retainer plate 24 suitably recessed to engage against the slippers 19 to hold them in contact with the swash surface 18. The principal function served by spring 22 and retainer plate 24 is to urge the pistons outwardly from their cylinders during one half of each cylinder block revolution. The spring within each cylinder will also help to urge the pistons outwardly.

A pair of

adjustable stops

25 and 26 within the casing 1 are provided to engage the swash plate 16 to determine its limits of angular adjustment about the axis 17.

A plurality of passages 27 are provided within the cylinder block, one between each adjacent pair of cylinders and in close proximity to bearing 4. These passages open into the chamber 40 of the casing 1 enclosing the swash plate 18 and extend back to open to the side of the cylinder block into an annular chamber 28 defined between the casing, the cylinder block, the bearing 4 and the valve block. This chamber is the delivery region. A vane 39 formed on the interior surface of the casing projects in the chamber 28 to reduce rotary flow of liquid around the chamber 28. The walls of the passages 27 form kinetic pumping surfaces which have radial portions to pump liquid by centrifugal action from the inlet 15 over the swash plate 16 and into the chamber 28. It is equally within the scope of this invention that the passages 27 could be skewed relatively to the axis of block rotation to effect axial flow kinetic pumping.

Rotational drive is supplied to the cylinder block 3 through the medium of a drive shaft 29 having a splined connection 31 within the block 3. The shaft 29 is supported within a sleeve 32 carried within

bearings

33 and 34 in the valve block 2. A seal 35 co-operates with the sleeve 32 to prevent escape of liquid. A hollow space 36 is formed around the sleeve 32 and this is connected by a passage 37 with the recess 30. The passage 37 will ensure that high pressure liquid escaping from the inner edge of the surfaces 8 and 11 is fed back to the inlet port 12 thus preventing any substantial pressure from acting on the seal 35. Such liquid will also have access to the

bearings

33 and 34 and ensure that they are adequately lubricated.

In operation of the described embodiment rotary driving power is supplied to the shaft 29 to rotate the cylinder block 3. During such rotation the slippers will be held in contact with the swash plate 18 and thus the pistons will be forced to reciprocate within their cylinders. The driving direction is such that when the pistons are moving out of their cylinders the associated cylinder ports 9 are in connection with the inlet port 12. When the pistons are moving into their cylinders the associated cylinder ports 9 are in connection with the delivery port 13. The cross-section through the valve block 2 has been deliberately taken on a plane at right angles to the cross-section through the cylinder block and swash plate in order that the ports 12 and 13 may be shown in the drawings. Liquid enters the pump through the inlet into chamber 40 and rotation of the cylinder block and the passages 27 gives a small pressure rise from the inlet 15 into the delivery chamber 28. The vane 39 reduces flow of liquid around the delivery chamber and will help to increase the small pressure rise generated within the chamber 28. From the chamber 28 liquid has direct access into the inlet port 12 both through its opening in the edge of plate 11 and through the recess 30 and thus to flow into the cylinders whose pistons are moving outwardly. The flow of liquid induced by the passages 27 will pass over the swash plate at the temperature at which it enters the inlet 15 and will ensure adequate lubrication and cooling of the slippers and swash plate. The bearing 4 around the end of the cylinder block 3 remote from the valve block 2 is so positioned that the side thrust exerted by the slippers on the pistons will pass substantially directly through the bearing 4 and thus will not generate any substantial tipping moment on the cylinder block 3. The bearing 4 forms a seal between the chamber 40 and the chamber 28. The flow of liquid through passages 27 in close proximity to bearing 4 ensures adequate cooling of bearing 4.

I claim:

1. A swash plate device comprising a rotary cylinder block having cylinders disposed parallel to or inclined to the rotation axis, valve means cooperating with the cylinder block during rotation to connect the cylinders to the fixed high pressure port cyclically during rotation of the cylinder block, a swash plate. adjacent one end of the cylinder block, pistons in the cylinders cooperating with the swash plate whereby the pistons will reciprocate during cylinder block rotation, a casing %%%?l%f & ;llel"%fc "sd ztems a swafl plate having a cylindrical journal bearing surface engaging within a complementary cylindrical bearing surface within the casing to divide the casing into two chambers, and passages extending through the cylinder block in close proximity to the cylindrical bearing surfaces whereby the flow of liquid through said passages cools said surfaces, said passages connecting the two chambers for the flow of liquid therethrough during operation of the device.

2. A swash plate device as claimed in claim 1 including a liquid inlet connection into the chamber enclosing the swash plate, a fixed low pressure port within the valve means for connection cyclically to the cylinders during rotation of the cylinder block and a liquid flow connection from the chamber located between the cylindrical bearing surfaces and the valve means and the said fixed low pressure port whereby liquid flowing through the chambers and the passages may enter the said low pressure port.

3. A swash plate device as claimed in claim 2 wherein the said passages are arranged to provide a hydrokinetic pumping effect between one chamber and the other.

4. A swash plate device as claimed in claim 3 wherein a substantial part of each passage in the cylinder block extends parallel to the rotation axis of the cylinder block.

5. A swash plate device as claimed in claim 4 wherein the number of passages is equal to the number of cylinders in the block and a passage is located between each adjacent pair of cylinders.

Claims

1. A swash plate device comprising a rotary cylinder block having cylinders disposed parallel to or inclined to the rotation axis, valve means cooperating with the cylinder block during rotation to connect the cylinders to the fixed high pressure port cyclically during rotation of the cylinder block, a swash plate adjacent one end of the cylinder block, pistons in the cylinders cooperating with the swash plate whereby the pistons will reciprocate during cylinder block rotation, a casing enclosing the cylinder block and swash plate, the end portion of the cylinder block adjacent to the swash plate having a cylindrical journal bearing surface engaging within a complementary cylindrical bearing surface within the casing to divide the casing into two chambers, and passages extending through the cylinder block in close proximity to the cylindrical bearing surfaces whereby the flow of liquid through said passages cools said surfaces, said passages connecting the two chambers for the flow of liquid therethrough during operation of the device.