US3663125A

US3663125A - Hydraulic pump

Info

Publication number: US3663125A
Application number: US92041A
Authority: US
Inventors: Frank George Freeman
Original assignee: Lucas Industries Ltd
Current assignee: ZF International UK Ltd
Priority date: 1970-11-23
Filing date: 1970-11-23
Publication date: 1972-05-16
Anticipated expiration: 1989-05-16

Abstract

A radial-piston hydraulic pump has its inlet and outlet interconnected by a valve. A closure member for the valve is rotated with the pump rotor and is urged open against a biasing spring by a part of the rotor which acts as a governor. The valve opens when the pump speed exceeds a predetermined value.

Description

United States Patent Freeman 51 May 16, 1972 [54] HYDRAULIC PUMP [72] inventor: Frank George Freeman, Solihull, England [73] Assignee: Joseph Lucas (Industries) Limited, Birmingham, England [22] Filed: Nov. 23, 1970 [21] Appl.No.: 92,041

[52] US. Cl ..4l7/294, 91/478, 91/498 [51] Int. Cl ..F04b 49/02 [58] Field of Search ..4l7/294, 293;9l/478,498

[56] References Cited UNITED STATES PATENTS 1,431,593 10/1922 ()swald ..4l7/294 X Freeman ..4l7/294 X Tomita ..4l7/284 X Primary Examiner-Carlton R. Croyle Assistant ExaminerRichard Sher Attorney-Holman & Stern 57 ABSTRACT A radial-piston hydraulic pump has its inlet and outlet interconnected by a valve. A closure member for the valve is rotated with the pump rotor and is urged open against a biasing spring by a part of the rotor which acts as a governor. The valve opens when the pump speed exceeds a predetermined value.

6 Claims, 4 Drawing Figures PATENTEDMAY 16 I972 SHEET 1 OF 2 INVENTOR Zi M m e kit WM wvu ATTORNEYS HYDRAULIC PUMP This invention relates to hydraulic pumps of the type having a rotor, a plurality of radial bores in the rotor, a plurality of pistons slidable in the bores, an annular member eccentrically of the rotor and upon whose inner face the pistons engage, an inlet and an outlet.

According to the invention a pump of the type described includes a valve means between the inlet and the outlet, the valve means comprising a port and a closure member which rotates, in use with respect to the port, biasing means for the closure member in a direction to shut the valve and means responsive to the speed of the rotor to open the valve.

An embodiment of the invention will now be described by way of example and with reference to the accompanying drawings in which:

FIG. 1 is a section through a pump and FIGS. 2 and 3 are sections on the corresponding lines in FIG. 1, the moving parts of the pump being shown in different positions in FIG. 2 from those shown in FIGS. 1 and 3, and

FIG. 4 shows diagrammatically a development of the periphery of a part of the pump.

A pump has a body formed in two parts 10, 11. Part 11 has in inlet port 12 and two

outlet ports

13, 14. Part 11 also has an inwardly extending boss 15 about which a rotor 16 may be driven by a shaft 17. Pistons 18 are slidable in bores 21 in the rotor 16 and incorporate slippers 19 which engage an inner face 20 of the body part 10. The face 20 is disposed eccentrically with respect to the boss 15.

The bores 21 open on to the inner surface of the rotor 16 via passages 27. The boss 15 is formed with an axial passage 22 and a further passage 23 in spaced parallel relationship with the passage 22.

Passages

22, 23 respectively communicate with

outlets

13, 14 and with

respective ports

24, 25 which open on to the outer face of the boss 15.

As shown in FIG. 4 the center of the port 25 is offset axially of the boss 15 from the center of the port 24. A portion of the boss 15 is removed to form a further port 26 which commu nicates with the inlet 12.

Circles

27a, 27b, 27c in FIG. 4 show three of the positions of the passages 27 with respect to the

ports

24, 25, 27 as the rotor 16 turns about the boss 15.

A part 28 of the rotor is pivotally mounted on the remaining part thereof and has an arm 29 extending radially towards the passage 22. Slidable within the passage 22 is a closure member 31 which co-operates with the passage 22 to form a valve and which includes a stem and a piston-like guide 32 formed with a slot 34 in which the arm 29 engages. A spring 35 biases the closure member 31 in a direction to close the valve and to urge the part 28 into close contact with the remainder of the rotor 16, in which position it lies within the volume swept by the rotor 16 as it revolves.

In use the rotor 16 is driven by an external means (not shown) coupled to the shaft 17. The pump operates in a known manner to draw fluid via the inlet 12 and port 26 and to discharge it via the

ports

24, 25 to the

respective outlets

13, 14. It will be seen from FIG. 4 that each of the passages 27 communicates with only one of the

ports

24, 25, 26 at any time, that there is a very short interval during which each passage 27 is not communicating with one of the said ports, and that at least one of the passages 27 is incommunication with the port 24 at all times. Delivery from the outlet 13 is thus continuous. Delivery from the outlet 14 is in the form of pulses.

If the rotor speed rises above a predetermined value the part 28 pivots outwards to compress the spring 35 and to move the closure member 31 so as to permit some of the fluid in the passage 22 to return to the inlet 12. The amount of fluid thus returned to the inlet 12 will thus be dependant on the rotorspeed. The arm 29 engaging in the slot 34, rotates the stem 30 with respect to the boss 15. The effects of static friction between the stem 30 and boss 15 are thereby substantially eliminated.

Having thus described my invention what 1 claim as new and desire to secure by Letters Patent is:

l. A pump having a rotor, a plurality of radial bores in the rotor, a plurality of pistons slidable in the bores, an annular member disposed eccentrically of the rotor, upon an inner face of which member the pistons engage, an inlet, an outlet, valve means between the inlet and outlet, the valve means comprising a port and a closure member which rotates, in use, with respect to the port, biasing means for the closure member in a direction to shut the valve and means responsive to an increase in the speed of the rotor to open the valve.

2. A pump as claimed in claim 1 in which the said means responsive to the rotor speed comprises a part of the rotor pivotally mounted on the remainder of the rotor and coacting with the closure member.

3. A pump as claimed in claim 2 in which the said rotor part is in driving engagement with the closure member so that the latter is, in use, rotated by the rotor.

4. A pump as claimed in claim 3 in which the rotor is mounted on an axial boss and the said closure member is slidable in a bore in the said boss.

5. A pump as claimed in claim 4 which has a pair of outlets one of which communicates with the said bore in the boss and the other of which outlets communicates with a further bore in the boss.

6. A pump as claimed in claim 5 in which, in use, the said one outlet successively communicates with the said radial bores so as to provide a substantially continuous delivery from said one outlet, and the said further outlet successively communicates with the said radial bores so as to provide an intermittent delivery from said further outlet.

Claims

1. A pump having a rotor, a plurality of radial bores in the rotor, a plurality of pistons slidable in the bores, an annular member disposed eccentrically of the rotor, upon an inner face of which member the pistons engage, an inlet, an outlet, valve means between the inlet and outlet, the valve means comprising a port and a closure member which rotates, in use, with respect to the port, biasing means for the closure member in a direction to shut the valve and means responsive to an increase in the speed of the rotor to open the valve.