US2511573A - Vane pump construction - Google Patents

Description

J ne. 13, 5 w. G. FINLAYS ON ETAL 2,511,573

vm PUIP cons-mucnon Filed llarch 29, 1946 2 Sheets-Sheet 1 INVENTORS WILLIAM G.FINL.AYSON HARRY H- BROWN JOSEPH J MGINNIS AT TORNEY June 1950 w. G. FINLAYSON ETAL 2,511,573

vm: PUIIP cons'muc'rzon Filed March 29, 1946 2 sheets-sheet 2 INVENTORS WILLIAM G. FINLAYSON HARRY H. BROWN- JOSEPH J m cmms BY JIM ATTORNEY Patented June 13, 1950 VAN E PUMP CONSTRUCTION William G. Finlayson, Harry B. Brown, and Joseph J. McGlnnis, Detroit, Mich., assignors to Vickers Incorporated, Detroit, Mich., a corporation of Michigan Application March 29, 1946, Serial No. 658,108

3 Claims.

This invention relates to power transmissions. particularly to those of the type comprising two or more fluid pressure energy translating devices, one of which may function as a pump and another parts of the pump such as the shaft bear ings, end plates, etc. I

A further object is to provide an improved pump construction which can be operated at far other as a fluid motor. greater speeds, higher pressures and larger de- The invention is more particularly concerned livery rates andwhich will, in addition, have a with a vane pump construction particularly longer life. These and other objects are acadapted for use in hydraulic power transmission complished by a construction wherein the fluid systems. pressure forces acting on the vane in a radial di- In the patent to Vickers No. 1,989,900, there is rection are in substantially complete balance at disclosed a rotary vane pump which has found all times during the cycle of rotation. wide commercial use in its fleld. In a pump of Further objects and advantages of the present this type, the working chambers are defined by a invention will be apparent from the following degenerally oval cam ring and a slotted rotor scription, reference being had to the accompanycarrying a plurality of radially slidable vanes 5 ing drawings wherein a preferred form of the contacting the ring. Pumps of this construction present invention is clearly shown. have been found eminently suitable as sources of p In the drawings: high pressure fluid for power purposes over a Figure 1 is a longitudinal cross-section of a fairly wide range of operating conditions. Howrotary vane pump embodying a preferred form of ever, one limiting factor in their design has been the present invention. found to be the rate of wear between the outer Figure 2 is a transverse cross-section of the ends of the vanes and the elliptical surface oftthe wolr iking elements of ti? pump. ring. Although a certain amount of wear, at his gures 3 and 4 are ragmentary cross-sections point, is permissible without interfering with the corresponding to Figure 2 showing the parts in efliciency of the pump, it has been found that different positions. when certain limiting speeds, pressures, and Figure 5 is a cross-section on line 55 of volumetric capacities are exceeded that the wear Figure 2. rate is so great as to be economically unfeasible. Figure 6 is a cross-section on line 6-5 of One of the principal reasons for the success of Figure 2. v such pgimfps lies in $118 facit tlaiha very largs Referring 110mg tool ggure 1, theretis shownI a amoun o wear on e en s o e vanes an mam pump 0 y av ng concen ric annu ar to some extent also on the ring can be permitted passages l2 and 14 which communicate, respecvgithonly a slfight effect (on tthetielfllgientcirl loil; tifvely, lwfith outlet and inleti upumpbconnecticizng t. e pump. ,0 course, is ue o e ac a o usua orm. e ousing may e suppor e the vanes are maintained in contact with the onamounting bracket l6 secured thereto by bolts ring by centrifugal force and fluid pressure and I8. Formed in the housing I0 is a cylindrical that the pumping action is independent of hofiw :gvity ill agaat ed t b lgsgd gt a g ap much the tips of the vane have been worn o secure 9 18 y 0 s our- However, if the rate of wear is excessive, the pump milled 0n bearings 25 and n m the houslng Q life becomes too short to be commercially acceptrespectively is shaft havmg able. Consequently, pumps of this construction g gggs drive portion mtermedlate h have heretofore been limited in their ratings to Mounted within the cavity 20 is a pump maximums i the nelghborhood of 1000. pounds, cartridge generally designated 34 The cartridge sfuare mch ii 1800 j z g i per 34 comprises a pair of similar flanged bushings m e and 6 ga ons per mmu e 6 Very 36 preferably formed of bearing material such as Whlle y attempts have been to :bronze. The'bushings 36 are provided with four struct satisfactory pumps of this type with higher arcuate openings or ports 38 and 40 arranged, ratings than th s, none have been successful prior 1 diametrically opposed pairs. The ports 38 of the Present lnventlonthe right-hand bushing in Figure 1 communicate It is an object of the present invention, therewith the outlet or pressure passage l2 by means fore, to provide an improved rotary vane pump of cored passages indicated at 42. Likewise, the construction having a far lower rate of wear at ports 40 communicate with the inlet or suction the critical surfaces of the vanes and ring so passage II by cored passages 44. that it is no greater than the wear rate on the as Radiall inward or the ports 38, the inner face of the bushing is provided with a pair of recesses 46 which communicate with the ports, 38 by means of grooves 48. The ports 38 and 40 extend completely through the flange of the bushings whereas the recesses 46 and grooves 48 are formed in the inner face only as seen more clearly in Figure 6. The ports 38 atone end are provided with extensions 50 in the nature of restricted grooves in the face of the bushings and similar grooves 52 are provided atone end of the recesses 46. Preferably, the grooves 52 are somewhat longer and of much smaller cross-section than the grooves 50 for a purpose later to be described.

Radially inward oithe ports 40 there are formed a pair of ports 54 which extend through the bushings from face to face and communicate with the ports 40 on the outer face of the bushings by a wide groove 58 as seen more clearly in Figure 5.

The cartridge also comprises a cam ring 58 of hardened steel, or high grade cast iron such as meehanite which lies between the flanges of the bushings 36 and closely fits the cylindrical recess of the housing. The ring 58 has a cam track of generally elliptical form which preferably isformed of two circular arcs on its minor diameter extending from the edge of port 38 to the 7 edge of port 40, two other circular arcs on its major diameter extending between ports 38 and 40 together with two inlet and two outlet ramps connecting these arcs by a suitably curved surface. The main body I0, bushings 36 and ring 58 together may be considered to form a housing for the moving parts of the pump.

Jonrnalled m the tubular portion of the bush-- ings 38 is a rotor 50 having a plurality of substantially radial vane slots 6i formed in its periphery.. The vane slots are slightly inclined with their outer ends forward of their inner ends in the direction of rotation in the preferred form illustrated. The inner ends of the vane slots register in turn during rotation of the rotor with the recesses 46 and ports 54, the latter constituting what may be termed slot outlet and slot inlet ports, respectively. Positioned in each of the slots are flat rectangular vanes 62 of hardened steel which are of the same width as the rotor and ring and which are freely slidable in and out in the slots. The outer edge of each vane 62 is preferably bevelled so that it contacts the ring only at the trailing edge and for this purpose, the vanes may be bevelled either to a very sharp edgeor to a slightly dulled one which presents only a minute contact area to the ring 58.

The central chamber of the pump in which the shaft is located may be connected to the inlet passage l4 by a suitable drain conduit 64 and a shaft seal 66 provided adjacent to bearin 28.

In operation, when the shaft 30 is driven counterclockwise in Figures 2, 3, and 4, fluid will be taken in through the pump inlet and suction ports .40 to the working chambers between the rotor and ring in the well-known manner. The vanes will carry this fluid across the lands in the bushings between ports and 38 and deliver itto the outlet ports 38 andpump outlet passage l2. In this respect, the action is identical to that described in more detail in the Vickers patent previously referred to.

The greatly improved wear characteristics of the present construction are obtained by the arrangement shown for controlling the application of pressure to the bottom of the vane slots. Considering clockwise rotation, the ends of ports 44 and 54 shown in Figure 3 may be termed trailing edges (as respects the vanes sweeping past them) and the extensions 50 and 52 may be considered the leading edges of ports 38 and 4'. As more clearly shown in Figure 3, each vane as it leaves the trailing edges of the suction ports 40 is simultaneously cut of! from the slot suction ports 54. As the rotor advances to the position shown in Figure 4, the slot is first connected to the slot outlet ports 48 through the restricted extensions 52. This enables a gradual build-up of pressure at the inner end of the vane to occur, and, at about the same time or preferably just slightly later, the vane ahead of the one under consideration passes on to the restricted extension 50 of the main outlet port 38. This admits pressure to the working chamber which, although full of oil, was previously at suction pressure. Due to the very slight compressibility of oil, a very slight flow will take place through the restricted passage 50 and compress the oil in the working chamber up to delivery line pressure. The design of the restricted passages 50 and 52 is such that having regard to the volume to be compressed in the working chamber and the volume to be compressed at the inner end of the vane slot, the pressure build-up at both points occurs at the same rate and simultaneously.

It will be noted that due to the bevel on the leading edge of the vane tipe that the pressure in the working chamber acts radially inward over substantially the full cross-sectional area of the vane and this is balanced by a similar pressure acting at the inner ends of the vane slots. Thus, substantially, the only force acting on the vane is that due to centrifugal force. It will also be noted that the bevel at the tip of the vane forms an oil film wedge which assists in lubricating the point of contact between the vane tip and the ring, thus giving the vane a tendency to ski" on a film of oil.

While the form of embodiment of the invention as herein disclosed constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

What is claimed is as follows:

1. A rotary vane pump comprising a housing having a generally elliptical working chamber provided with a pair of diametrically opposite main inlet ports and a pair of diametrically obposite main outlet ports, a rotor in the cham her having a plurality of generally radial vane carrying slots, vanes slidable in the slots and having their outer ends bevelled to contact the surface of the working chamber at their trailing edges, a pair of diametrically opposite slot inlet ports and a pair of diametrically opposite slot outlet ports positioned to register with the inner ends of said slots, said housing providing a first pair of lands between the trailing edges of the main inlet ports and the leading edge of asums respectively, establish communication with the outlet ports.

2. A rotary vane pump comprising a housing having a generally elliptical working chamber provided with a pair of diametrically opposite main inlet ports and a pair of diametrically opposite main outlet ports, a rotor in the chamber having a plurality of generally radial vane carrying slots, vanes slldable in the slots and having their outer ends bevelled to contact the surface of the working chamber at their trailing edges, a pair of diametrically opposite slot inlet ports and a pair of diametrically opposite slot outlet ports positioned to register with the inner ends of said slots, said housing providing a first pair of lands between the trailing edges of the main inlet ports and the leading edges of the main outlet ports, and a second pair of lands between the trailing edges of the slot inlet ports and the leading edges of the slot outlet ports, the first pair of lands extending over a greater arc than the second pair by substantially the arc between adjacent vanes whereby pressure is applied to both inner and outer ends of the vanes at the same instant, the main and slot outlet ports having a restricted portion adjacent their leading edges to cause a gradual build-up of pressure as the vanes and the inner ends of the slots. respectively, establish communication with the outlet ports, said restricted portions being proportioned in relation to the fluid volume in the working chamber between vanes and the volume in the vane slot to cause a pre-determined ratio of pressure build-up in those fluid volumes.

3. A rotary vane pump comprising a housing having a generally elliptical working chamber provided with a pair of diametrically opposite main inlet ports and a pair of diametrically opposite main outlet ports, a rotor in the chamber having a plurality of generally radial vane carrying slots, vanes slidable in the slots and having their outer ends bevelled to contact the surface of the working chamber at their trailing edges, 9. pair of diametrically opposite slot inlet ports and a pair of diametrically opposite slot outlet ports positioned to register with the inner ends of said slots, said housing providing a first pair of lands between the trailing edges of the main inlet ports and the leading edges of the main outlet ports, and a second pair of lands between the trailing edges of the slot inlet ports and the leading edges of the slot outlet ports, the first pair v of lands extending over a greater arc than the second pair by substantially the are between adjacent vanes whereby pressure is applied to both inner and outer ends of the vanes at the same instant, the main and slot outlet ports having a restricted portion adjacent their leading edges to cause a gradual build-up of pressure as the vanes and the inner ends of the slots, respectively, establish communication with the outlet ports, the restricted portion at the slot outlet port being smaller than the restricted portion at the main outlet port,

WILLIAM G. FINLAYSON. HARRY H. BROWN. JOSEPH J. McGINNIS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS

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