US3267871A

US3267871A - Hydraulic apparatus

Info

Publication number: US3267871A
Authority: US
Inventors: Lee Dennis Ernest; Palmer Kenneth Percy
Original assignee: Lucas Industries Ltd
Current assignee: ZF International UK Ltd
Priority date: 1963-06-19
Filing date: 1964-06-17
Publication date: 1966-08-23
Anticipated expiration: 1983-08-23
Also published as: DE1291632B; SE301271B; GB1069671A

Description

I966 D. E. LEE ETAL 3,267,871

HYDRAULIC APPARATUS Filed June 17, 1964 2 Sheets-Sheet 1 b N Q:

L 31 E 7i J :1 F:

Aug. 23, 1966 E. LEE ETAL HYDRAULIC APPARATUS 2 Sheets-Sheet 2 Filed June 17, 1964 United States Patent 3,267,871 HYDRAULIC APPARATUS Dennis Ernest Lee, Acocks Green, Birmingham, and Kenneth Percy Palmer, Solihull, England, assignors to Joseph Lucas (Industries) Limited, Birmingham, England Filed June 17, 1964, Ser. No. 375,784 Claims priority, application Great Britain, June 19, 1963,

4 Claims. (Cl. 103-162) This invention relates to hydraulic apparatus of the kind comprising a rotatable rotor having formed in an end face, ports through which fluid passes as the rotor is rotated, and a non-rotatable valve plate arranged adjacent to said end face, said valve plate incorporating a passage through which fluid passes to or from said ports in turn.

In such apparatus it is desirable that the clearance between the rotor and the valve plate should be maintained substantially constant at a value which will be selected to provide the minimum power loss due to the combination of flow leakage and shearing of the resulting lubricant film irrespective of any axial movement of the rotor, and the object of this invention is to provide in a simple and convenient form apparatus of the kind specified in which this desideratum is achieved.

According to the invention apparatus of the kind specified includes a piston, one end of which is arranged to be subjected to a fluid pressure, the magnitude of which is, at least in part, determined by clearance between the valve plate and the rotor end face, the arrangement being such that the force exerted by the piston on the valve plate will be such as to maintain the clearance substantially constant.

One example of the invention will now be described with reference to the accompanying drawings in which:

FIGURE 1 is a cross-sectional view of a pump incorporating the invention, taken on the line 11 in FIG- URE 2,

FIGURE 2 is a cross-sectional view on the line 22 in FIGURE 1,

FIGURE 3 is a fragmentary view of an alternative construction.

In the example of the invention shown in FIGURES 1 and 2, as applied to a liquid fuel pump there is provided a hollow composite pump body in which is rotatably mounted a rotor 11 incorporating a plurality of axially extending cylinders which terminate at their inner ends in ports 12 extending to the adjacent end face of the rotor 11.

Mounted between the ported end face of the rotor 11 and the adjacent face of the body 10 is a valve plate 13 which is restrained from angular movement but is permitted axial movement relative to the body 10. Extending through the valve plate 13 are a pair of

arcuate passages

14, 15 respectively with which the ports 12 in the rotor co-operate in turn as the rotor is rotated. The passages are in communication with complementarily disposed ways in the body 10 these ways comprising an inlet 16 and an outlet 17 respectively in the body 10.

Within the cylinders in the rotor 11 are mounted a plurality of reciprocable pistons 18 respectively which are arranged to be moved inwardly in the cylinders by interaction of slippers 19 formed respectively on the ends of the pistons 18 remote from the valve plate 13 with an obliquely disposed cam plate 20 mounted in the body 10 and the arrangement is such that when the rotor 11 is rotated, fuel will be drawn into the cylinders from the inlet 16 whilst the pistons 18 are moving outwardly, and will be displaced from the cylinders, when the pistons are moved inwardly by the cam plate 20, to the outlet 17.

The rotor 11 is mounted on a shaft 21 which extends out of the body 10 and is adapted to be driven, as conice venient, one arrangement being shown at 22 in FIG- URE 1.

In such pumps or other similar hydraulic apparatus, it is desirable that the valve plate 13 should be maintained in scaling engagement with the end face of the rotor 11 in order to minimize leakage. At the same time, however, there must be sufficient clearance to allow an adequate lubricant film to be established therebetween. Moreover the valve plate 13 must seal with the adjacent face of the body 10.

In applying the invention to such a pump the end portion ofthe body in which the inlet and outlet ways are formed, has a plurality, for instance, three cylinders 23 containing respective pistons 24 movement of each of which is limited by a block 25 and by a tubular part 26 respectively. The tubular part 26 is, moreover slidably mounted in the body. The end of the cylinder 23 in which the block 25 is disposed is open to the outlet way 17 formed in the body through a bore 27.

The opposite end of the tubular part 26 from the cylinder 23 bears against the valve plate and communicates with a passage 28 therethrough which terminates in the face of the valve plate adjacent to the rotor. Thus the passage 28 and the bore of the tubular part 26 can partake of fluid pressure conditions in the region between the valve plate 13 and the rotor 11. Transverse passages 29 are formed in the tubular part 26 and afford communication between the bore of that part and the end of the cylinder 23. The passage 28 in the valve plate 13 also communicates with the outlet passage 15 through a restricted passage 30.

In operation, if the clearance between the valve plate and the rotor decreases, fluid, which is normally permitted to escape from the passage 28 into this clearance space from the outlet passage 15, through the passage 30, instead increases the pressure in the end of the cylinder 23 to move the piston towards the block 25. This enables the tub-ular part 26 to move in the same direction thus permitting consequential movement of the valve plate to increase the size of the clearance.

If, however, the clearance increases, there will be a fall in pressure in the end of the cylinder 23 thus permitting movement of the piston, and the tubular part and valve plate in the direction to decrease the clearance, this movement being under the influence of the pressure exerted on the piston 24 by fluid entering the cylinder 23 through the passage 27, trom the outlet way 17.

In an alternative construction shown in FIGURE 3, the outlet way 17 in the body 10 is formed as a plurality of stepped cylindrical ways and the associated passage 15 in the valve plate 13 is similarly formed. In the stepped ways are accommodated stepped and hollow pis tons 31 respectively. The narrower ends of each piston 31 extends into the stepped passage 15 in the valve plate 13. In use, the pressure of fuel in the way 17 acts against the wider end of the piston 31 to urge the valve plate 13 towards the rotor 11. More-over, the stepped pistons 31 have annular seals 32 mounted in their peripheries so as to ensure a fluid tight connection between the valve plate 13 and the body 10.

In order that the force exerted by the pistons 31 may be controlled, an annular gap 33, defined between the step of the piston 31 and the step of the cylindrical way 17, is in communication with the way through a restricted passage 34 of predetermined size, formed in the piston 31. The annular gap 33 is also in communication with a passage 35 formed in the valve plate 13, the effective flow through which is controlled by the gap between the valve plate 13 and rotor 11. This latter communication is through a passage 36, and a cylinder 37 containing a tubular bobbin 38 which affords a sealing connection between the body 10 and valve plate 13.

When the pump is in use, and the clearance between the valve plate 13 and the rotor 11 increases, the pressure in the annular gap 33 will be lower than the pressure in the way 17 and the piston 31 will move the valve plate 13 so that the clearance is reduced. If, however, the clearance decreases, the pressure in the annular gap 33 will be nearly the same as the pressure in the way 17, with the result that the force exerted by the piston 31 on the valve plate 13 will be reduced and the clearance will be increased because the valve plate 13 will be moved away from the rotor 11 by the fluid pressure acting thereon.

By a construction as described effective control of the clearance between the rotor and valve plate is maintained.

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

1. Hydraulic apparatus comprising a body, a rotor mounted within the body, the rotor having, in an end face, ports through which fluid passes as the rotor rotates, a non-rotatable valve plate disposed between said end face of the rotor and the body, the valve plate having a passage through which fluid passes to and from said ports in the rotor, and a piston in a cylinder formed in the body, the end of the cylinder at the side of the piston remote from the valve plate communicating with said passage in the valve plate, and the other end of the cylinder at the side of the piston nearer to the valve plate communicating with the interfaces of the rotor and of the valve plate, and also with said passage in the valve plate.

2. Hydraulic apparatus as claimed in claim 1 in which a tubular part is disposed between the piston and the valve plate and is arranged to transmit movement of the piston to the valve plate, said tubular part defining a passageway affording communication between the end of the cylinder at the side of the piston nearer to the valve plate and said interfaces and passage.

3. Hydraulic apparatus as claimed in claim 1 in which the cylinder is stepped and the piston defines a restricted passage for flow' between opposite ends of the cylinder, and the body defines, in part, a passage communicating with said interfaces. p

4. Hydraulic apparatus as claimed in claim 1 in which there is a plurality of spaced pistons in respective cylinders in the body.

References Cited by the Examiner UNITED STATES PATENTS 2,484,337 10/1949 Ferris 103l62 2,525,498 10/1950 Naylor et al. 103162 2,845,941 8/1958 Wagner 103-162 2,977,891 4/1961 Bishop 103-162 3,037,489 6/1962 Douglas 103-162 MARK NEWMAN, Primary Examiner. SAMUEL LEVINE, Examiner.

R. M. VARGO, Assistant Examiner.