GB1590254A

GB1590254A - Swash plate pump or motor

Info

Publication number: GB1590254A
Application number: GB2368578A
Authority: GB
Original assignee: Glacier Metal Co Ltd
Current assignee: Federal Mogul Engineering Ltd
Priority date: 1978-05-30
Filing date: 1978-05-30
Publication date: 1981-05-28
Also published as: DE2917771A1; JPS555489A

Description

(54) SWASH PLATE PUMP OR MOTOR (71) We, THE GLACIER METAL COM PANY LIMITED, a Company registered under the Laws of England, of 368, Ealing Roads Alperton, Wembley, Middlesex, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be paticularly described in and by the following statement: This invention relates to swash plate pumps and motors of the rotating cylinder block type, and one object of the present invention is to provide a simplified construc tion of the main sliding bearing surfaces.

In the past, it has been the practice to provide different pairs of bearing materials for different sliding surfaces depending upon the function of those surfaces. For example, -the port plate and cylinder block sliding bearing surfaces have been often of cast bronze while the swash plate pivot surface has been of a sintered graphite and P.T.F.E.

composition.

Not only has it been inconvenient to have different types of bearing surfaces in different parts of the pump or motor, but the cast bronze port plate surfaces has required precision manufacture, has required fluid lubrication, and has been subject to quite serious wear.

According to the present invention, there is provided a swash plate pump, or motor, of the rotating cylinder block type, in which pairs of sliding bearing surfaces of main shaft bearings, a port plate and cylinder block bearing, and a swash plate pivot bearing each consist of one finished metal surface, and one polyphenylene sulphide surface.

If other sliding bearing surfaces require prepared bearing linings, for example the slipper and swash plate sliding bearing surfaces, the piston and push rod sliding bearing surfaces, and the relatively sliding piston and cylinder surfaces then in these cases also, each pair of surfaces can consist of one finished metal surface and one surface of polyphenylene sulphide.

It has been found that that particular combination of bearing surfaces is suitable for widely different functions provided there is fluid lubricant, without being subjected to very great wear, and without introducing substantial frictional losses, and it clearly is of advantage that all prepared bearing lining surfaces are of the same material.

Although the specification refers particularly to swash plate pumps, it is to be under stood that it also covers a machine of that kind when used as a motor.

The invention may be carried into practice in various ways, and one embodiment will, now be described by way of example, with reference to the accompanying drawing, of which the single figure is a diagrammatic sectional elevation of a swash plate pump of the rotating cylinder block type.

The pump, which can also operate as a motor, comprises a casing 1 in which is journalled at 18, a rotating cylinder block 2 which conveniently has seven or nine cylinders 8 equiangularly disposed cirdumfer- entially around the central axis. Two almost opposed cylinders are shown as the plane of the section - of the figure is taken through the centre lines of two of the cylinders. The two cylinders shown contain pistons 6 shown respectively at, or near top dead centre and bottom dead centre.

,The pistons- are biassed towards bottom dead centre by compresgion springs 11, and have on their outer ends part spherical recesses for ball ended push rods 13 having slippers 12 at their outer ends, which slide in relation to a swash plate 14 which can turn about a part cylindrical bearing 17 formed in the end of the casing 1 to be at an adjustable set angle to the normal to the axis of the rotating cylinder block in dependence on the desired delivery.

There is a journal bearing for the inner end of the cylinder block shaft in a cylindrical member mounted in the centre of the swash plate, as indicated at 19.

Delivery of fluid between an inlet and an outlet 4 and 5 in the case of a pump, and 5 and 4 in the case of a motor, is by way of valve controlled apertures in a port plate 3 rotatably mounted in relation to the cylinder block 8.

The general theory of operation of such a swash plate. pump is well understood, and the invention is only concerned with the nature of the sliding bearing surfaces respectively on the main journal bearings 18 and 19, on the swash plate tilt bearing 17, on the port plate surface bearings with the rotating cylinder block 8, on the piston and cylinder surfaces, on the slipper and swash plate surfaces 12 and 14, and on the ball joint bearing surfaces 13.

In the past, each of these sliding bearing surfaces has had a surface of a material particularly suited to its particular conditions of working, and to the possibility of using some of the high pressure operating fluid for lubrication.

The present invention contemplates using a common bearing material for all the bearing surfaces which require to be specially lined, and the bearing material that has been found to be suitable is polyphenylene sulphide which may consist of a layer bonded to a metal backing, or may consist of polyphenylene sulphide material which has been bonded to, or keyed into a sintered metallic backing surface, for example as described in British Patent Specification No. 1,475,295.

In accordance with the invention, the main bearings 18 and 19, the swash plate pivot bearing 17, and the port plate bearing 3 each consists of relatively sliding surfaces, one and one only of which carries polyphenylene sulphide while the other is a finished metal surface.

It is also possible for there to be similar sliding bearing surfaces respectively between the swash plate surface and the slippers 12, between the part-spherical bearing surfaces on the ends of the cylinders 6, and the ball 13 which rotate in them, and between the piston and cylinder sliding surfaces 6 and 8.

In these cases also, although one of each pair of sliding surfaces may be coated with polyphenylene sulphide, the other will be a finished metal surface.

It has been found that that type of bearing surface combination has low frictional losses if there is some liquid lubricant, while the wear is very slight.

The lubricant could be oil, or, in such applications as mine pumps where there is a danger of fire, could be an amulsion of 40 parts of water to 60 parts of oil.

WHAT WE CLAIM IS: 1. A swash plate pump, or motor of the rotating cylinder block type in which pairs of sliding bearing surfaces of main shaft bearings, a port plate and cylinder block bearing, and a swash plate pivot bearing each consist of one finished metal surface and one polyphenylene sulphide surface.

2. A pump or motor as claimed in Claim 1 in which the slipper and swash plate sliding bearing surfaces consist of one finished metal surface, and one polyphenylene sulphide surface.

3. A pump or motor as claimed in Claim 2 in which the relatively sliding piston and cylinder surfaces in each cylinder consist of one finished metal surface, and one polyphenylene sulphide surface.

4. A pump or motor as claimed in any of the preceding claims in which each pair of piston and push rod sliding bearing surfaces consists of one finished metal surface, and one polyphenylene sulphide surface.

5. A pump or motor of the rotary cylinder block type arranged substantially as herein specifically described, with reference to the accompanying drawing.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **.

rotatably mounted in relation to the cylinder block 8.

The general theory of operation of such a swash plate. pump is well understood, and the invention is only concerned with the nature of the sliding bearing surfaces respectively on the main journal bearings 18 and 19, on the swash plate tilt bearing 17, on the port plate surface bearings with the rotating cylinder block 8, on the piston and cylinder surfaces, on the slipper and swash plate surfaces 12 and 14, and on the ball joint bearing surfaces 13.

In the past, each of these sliding bearing surfaces has had a surface of a material particularly suited to its particular conditions of working, and to the possibility of using some of the high pressure operating fluid for lubrication.

The present invention contemplates using a common bearing material for all the bearing surfaces which require to be specially lined, and the bearing material that has been found to be suitable is polyphenylene sulphide which may consist of a layer bonded to a metal backing, or may consist of polyphenylene sulphide material which has been bonded to, or keyed into a sintered metallic backing surface, for example as described in British Patent Specification No. 1,475,295.

In accordance with the invention, the main bearings 18 and 19, the swash plate pivot bearing 17, and the port plate bearing 3 each consists of relatively sliding surfaces, one and one only of which carries polyphenylene sulphide while the other is a finished metal surface.

It is also possible for there to be similar sliding bearing surfaces respectively between the swash plate surface and the slippers 12, between the part-spherical bearing surfaces on the ends of the cylinders 6, and the ball

13 which rotate in them, and between the piston and cylinder sliding surfaces 6 and 8.

In these cases also, although one of each pair of sliding surfaces may be coated with polyphenylene sulphide, the other will be a finished metal surface.

It has been found that that type of bearing surface combination has low frictional losses if there is some liquid lubricant, while the wear is very slight.

The lubricant could be oil, or, in such applications as mine pumps where there is a danger of fire, could be an amulsion of 40 parts of water to 60 parts of oil.

WHAT WE CLAIM IS: 1. A swash plate pump, or motor of the rotating cylinder block type in which pairs of sliding bearing surfaces of main shaft bearings, a port plate and cylinder block bearing, and a swash plate pivot bearing each consist of one finished metal surface and one polyphenylene sulphide surface.
2. A pump or motor as claimed in Claim 1 in which the slipper and swash plate sliding bearing surfaces consist of one finished metal surface, and one polyphenylene sulphide surface.
3. A pump or motor as claimed in Claim 2 in which the relatively sliding piston and cylinder surfaces in each cylinder consist of one finished metal surface, and one polyphenylene sulphide surface.
4. A pump or motor as claimed in any of the preceding claims in which each pair of piston and push rod sliding bearing surfaces consists of one finished metal surface, and one polyphenylene sulphide surface.
5. A pump or motor of the rotary cylinder block type arranged substantially as herein specifically described, with reference to the accompanying drawing.