US3519370A

US3519370A - Radial-piston pump with improved cooling and lubrication

Info

Publication number: US3519370A
Application number: US712641A
Authority: US
Inventors: Aloys Bleuel
Original assignee: Alfred Teves GmbH
Current assignee: Continental Teves AG and Co oHG
Priority date: 1967-03-25
Filing date: 1968-03-13
Publication date: 1970-07-07
Anticipated expiration: 1987-07-07
Also published as: ES346229A1; JPS5019762B1; DE1653632A1

Description

July 7, 1970 A. BLEUEL 3,519,370

RADIAL-PISTON PUMP WITH IMPROVED COOLING AND LUBRICATION Filed March 15, 1968 2 Sheets-Sheet 1 FlG.l

ALOYS BLEUEL INVENTOR.

BY 5km T ATTORNEY July 7, 1970 A. BLEUEL 3,519,370

RADIAL-PISTON PUMP WITH IMPROVED COOLING AND LUBRICATION Filed March 13, 1968 2 Sheets-Sheet 2 ALOYS BLEUEL INVENTOR.

ATTORNEY United States Patent T 3,52 Int. Cl. F04b 23/04, 1/04, 39/02 US. Cl. 103-5 4 Claims ABSTRACT OF THE DISCLOSURE In a radial piston pump the hydraulic fluid is shunted on its path between the reservoir and the piston cylinders to flow past moving parts at the eccentric of the pump so as to cool and lubricate the latter, the shunt path including an axial bore formed in the eccentric shaft and opening beneath the bearing ring surrounding the eccentric.

The invention relates to a radial-piston pump supplying hydraulic pressure by means of an eccentric shaft which rotates in a cylinder housing in which the pumping pistons are radially disposed.

Hydraulic pumps of this type, preferably employed when high pressures are involved, demand very fine machining of the component parts, extremely close tolerances and the maintenance of constant lubrication between the moving parts. The latter task in particular requires continuous removal of the heat associated with high pressures and the correlated friction between moving parts. Furthermore, the efficiency of other pump components is liable to be affected by a thermal distortion of the lubrieating means or by their decomposition into substances which are ineflectual as lubricants or incompatible with the metallic and non-metallic parts with which they are in contact.

It is therefore the primary object of this invention to supply the working elements of a radial piston pump with the moderate environmental temperatures necessary to maintain the effective lubrication of the moving parts.

These objects and others which will bec me apparent hereinafter are attained, in accordance with the present invention, by routing the working hydraulic fluid on its way from the fluid reservoir to the piston cylinder intake chamber so as to flow past heat-sensitive surfaces and to carry away the undersirable heat. Specifically, the circuitous flow pattern leads fresh cool hydraulic fluid in and out of the rotor shaft which carries the slidable jacket designed to control the length of the piston stroke, and past and through the jacket or sleeve surrounding the eccentric.

According to a more specific feature of this invention, the eccentric shaft is rotatably received in a blind bore of the pump or cylinder housing which communicates, at its closed end, with the intake port of the pump and delivers hydraulic fluid to an annular suction chamber within the housing communicating with the pump cylinders. At least part of the fluid delivered from the intake portion to the suction chamber is passed through an axial bore formed in the eccentric shaft at its end proximal to the closed end of the axial bore of the housing. Spaced from this end of the shaft, there is provided an eccentric portion around which a bearing sleeve or jacket is disposed with peripheral clearance, the axial bore of the shaft opening within the sleeve via one or more radial ports formed in the eccentric portion of the shaft. The sleeve is, according to another feature of this invention, formed with openings communicating between its interior (with which the radial ports communicate) and the annular space in the axial bore of the housing surrounding the sleeve and into which the pistons project to contact the sleeve. This annular space is, in turn, connected with the suction chamber of the housing by one or more channels.

The system described generally above has the advantage that at least part of the hydraulic fluid displaced by the pump traverses the eccentric shaft and the bearing surfaces of the sleeve therearound before passage into the suction compartment and thus provides a constant stream of cool fresh lubricant and coolant.

The above and other objects, features and advantages of this invention will become more readily apparent from the following description, reference being made to the accompanying drawing in which:

FIG. 1 is an axial cross-sectional view, in part, of this invention in a somewhat schematical representation; and

FIG. 2 is a longitudinal cross-sectional view of the embodiment shown in FIG. 1 taken along the line II--II.

In FIGS. 1 and 2 there is shown a radial piston pump whose eccentric drive shaft 2 is rotatable in the housing 1 and has an eccentric portion 12 carrying the bearing jacket, sleeve or ring 3 on its circumference. The bearing 3 is radially shiftable on the shaft 2 and serves to displace a plurality of radial pistons 4 to pump the fluid upon rotation of the shaft 2 which is received in a closed-end axial bore 28. The radially extending cylinders 19 in which the pistons are slidable in the direction of the arrow 5 communicate with the annular low-pressure or suction chamber 21 and with the high-pressure discharge chamber 7 from which the hydraulic fluid is lead via outlet port 8. The spring-loaded check valves 20 between the heads of the cylinders 19 and the chamber 7 permits the fluid to flow only in one direction between the cylinder and the chamber 7.

The pistons 4, biased by the compression springs 6 in against the bearing sleeve 3, are two of a larger number (not shown) of piston elements radially disposed in the housing 1 and reciprocated between the intake or suction position indicated at 4a and discharge or com pression position indicated at 4b for the displacement of the hydraulic fluid.

According to this invention, the shaft 2 is provided with an axial bore 10 open at its end face 11 (proximal to the closed end of bore 28) toward an intake chamber 15 which communicates with the fluid-intake port 14 leading to the reservoir 14a. The bore 10 extends to a location in the interior of the shaft 2 which is approximately in line with the

pistons

4, 4a, 4b which lie in a common radial plane. Radial bores 13 (only one shown) lead from the axial bore 10 to the annular clearance 22 surrounding the shaft 2, where they terminate at a milled surface 9 which is surrounded by the annular clearance 22 between the sleeve 3 and this surface. The clearance 22 between the external surface of the eccentric portion 12 of shaft 2 and the inner wall 23 of the bearing sleeve 3, communicates, via radial milled slots 24 in the edges of bearing sleeve 3, with the annular space 25. Space 25 which receives the ends of the pistons 4 co-operating with the sliding jacket 3 as well as the sliding jacket, is connected by the radial channel 26 with the annular suction chamber 21. During radial inward movement, the leading edge 4' of each piston 4 is withdrawn sufficiently inwardly of edge 21' of the suction chamber to admit fluid into the respective cylinder ahead of the piston. During the outward movement of the piston, the edge 4' passes edge 21' to close the cylinder with further movement driving the fluid past the check valve into the outlet chamber 7.

The fluid flow, according to this invention, occurs in the direction of the arrows and broken lines and proceeds along a first conduit from the reservoir 14a through the port 14 into the chamber 15, past the proximate part of the frontal area 11 of the extremity of shaft 2, into the axial bore thereof, through the radial orifices 13 to the smooth milled surface 9 of the clearance 22 within the bearing sleeve 3, through the radial cutouts, notches or slots 24 in the axially opposite annular ends of the bearing sleeve 3, to the chamber 25 and from there through the radial passage 26 to the suction chamber 21. The cooling effected by the circulation of the fluid in the described manner is in excess of and supplementary to the heat transfer normally provided by the controlled leakage of hydraulic fluid in radial-piston pump systems. According to the drawing, the leakage is represented by the dot-dash lines leading from the chamber 25 through the narrow clearance between the shaft 2 and the bore 28 in which it is housed, into the radial channel 30 proximate to the packing or sealed bearing 27, and from therethrough the pas sageway 29 to the chamber 21.

What is claimed is:

1. A radial-piston pump comprising:

a housing formed with an axially extending housing bore;

an eccentric shaft rotatably received in said housing bore and provided with an eccentric portion therealong;

at least one cylinder formed in said housing and slidably receiving a piston driven by said shaft;

a suction chamber and a fluid-discharge chamber formed in said housing and communicating with said cylinder for displacement of fluid from said suction chamber to said discharge chamber upon rotation of said shaft and reciprocation of said piston;

a fluid-intake port formed in said housing;

a sleeve surrounding said eccentric portion of said shaft and acting upon said piston for displacing same upon rotation of said shaft, said shaft having a pair of bearing portions flanking said sleeve in said housing and being provided with an extremity; and

at least one passageway having at least a portion extending through said extremity of said shaft and communicating with said intake ports while opening Within said sleeve and between said sleeve and said eccentric portion for cooling the pump and lubricating said sleeve, said portion of said passageway being formed as an axial bore in said shaft and opening at said extremity thereof, said eccentric portion in said shaft being formed with at least one radial orifice communicating with the axial bore of said shaft and opening within said sleeve, said bearing portions defining leakage paths for said fluid between said intake port and said suction chamber so constructed and arranged that all fluid communication between said intake port and said suction chamber is constituted by said leakage paths and said axial bore, said sleeve defining an annular inner clearance with said eccentric portion of said shaft and an annular outer space with a wall of said housing both surrounding said sleeve, said orifice opening into said clearance, said sleeve being formed with at least one channel connecting said clearance with said space, said space being separate from said suction chamber, said housing being provided with a bore connecting said space with 4 said suction chamber and dimensioned to lead some of the fluid accumulated in said space into said suction chamber and to direct the remainder of said fluid along one of said leakage paths.

2. The pump defined in claim 1 wherein said channel is one of a multiplicity of notches formed in the opposite axial ends of said sleeve.

3. The pump defined in claim 1 wherein said piston and said cylinder lie in a radial plane of said housing, said orifice lying substantially in said plane and said axial bore of said shaft extending through the latter substantially to said radial plane.

4. The pump defined in claim 1 wherein said housing is formed with a fluid-intake chamber axially flanking said extremity of said shaft and communicating with said fluidintake port, said bore in said shaft communicating with said fluid-intake chamber and opening axially directly into the latter, one of said bearing portions being located between said intake chamber and said space and defining a first one of said leakage paths between said fluid-intake chamber and said space, said pump further comprising seal means surrounding said shaft remote from said extremity and defining a fluid-collection compartment around said shaft spaced from said space, the shaft region between said collection compartment and said space constituting the other bearing portion and defining the second of said leakage paths between said space and said collecting compartment, said suction chamber being angular and surrounding said shaft, said bore connecting said space with said suction chamber being generally radial, said housing being formed with a passage interconnecting said collection compartment and said suction chamber and having a cross-section larger than said bore connecting said space with said suction chamber, a plurality of such cylinders being formed in said housing in a common radial plane perpendicular to said shaft and in angularly equispaced relation about the axis thereof, each of said cylinders having a respective piston bearing radially upon said sleeve, said suction chamber communicating with all said cylinders, said fluid-discharge chamber being annular and coaxial with said suction chamber and communicating with all of said cylinders, each of said cylinders being provided with check-valve means permitting unidirectional fluid flow from said suction chamber to said fluid-discharge chamber upon reciprocation of the respective piston.

References Cited UNITED STATES PATENTS 2,394,285 2/ 1946 Beuins 103-174 2,612,837 10/1952 Midgette 103-174 2,693,150 11/1954 Dichard et al 103-174 2,865,292 12/1958 Raibaud 103-171 3,125,034 3/1964 Lucien 103-174 3,259,074 7/1966 Erdmann 103-174 FOREIGN PATENTS 902,097 8/ 1945 France.

WILLIAM L. FREEH, Primary Examiner U.S. Cl. X.R.