US2865297A

US2865297A - Injector cover for pumps

Info

Publication number: US2865297A
Application number: US327216A
Authority: US
Inventors: Cliborn Robert; Donald O Nordquest
Original assignee: Thompson Products Inc
Current assignee: Northrop Grumman Space and Mission Systems Corp
Priority date: 1952-12-22
Filing date: 1952-12-22
Publication date: 1958-12-23
Anticipated expiration: 1975-12-23

Description

Dec. 23, 1958 Filed Dec. 22, 1952 m Q1 2 2 mam vE 0 V a a w 1 w 3 m m INJECTOR 'UGVER FOR PUMPS Robert Cliborn and Donald (1?. Nordquest, Cleveland, Ghio, assignors to Thompson Products, lino, Cleveland, (thin, a corporation of Ohio Application December 22, 1952, Serial No. 327,216

2 Claims. (Cl. 103103) This invention relates generally to pumping apparatus and more particularly to a pump of the type having a shrouded impeller and having a pump cover which provides an annular chamber discharging through an injector gap to direct an annular sheath of fluid under high velocity into the central inlet of the impeller.

According to the general principles of the present invention, an impeller is provided which has a central inlet and which includes a plurality of pumping passage ways communicating with the central inlet and extending radially outwardly to the periphery of the impeller. A pump casing provides a volute pumping chamber for the impeller and a cover member on the end casing has an open ended inlet passageway adapted to lie in registry with the central inlet of the impeller.

An annular lip is provided at one end of the passageway and is situated adjacent an annular chamber formed in the cover member. The annular chamber communicates with the pump discharge through a plurality of circumferentially spaced metering passages.

A sleeve is received in the inlet passageway of the cover member and includes an end portion which provides a closure for the annular chamber, the end portion of the sleeve together with the annular lip forming an injector gap to direct a sheath of fluid across the lip under high velocity into the inlet of the impeller.

The sleeve is preferably adjustable in the passageway and to efiect that end, annular abutment shoulders may be provided between the sleeve and the cover member and shims are inserted between the annular abutment shoulders to selectively vary the width of the injector gap.

If the width of the injector gap is to be controlled automatically, a pressure fluid may be introduced into the area between the annular abutment shoulders and in one preferred embodiment shown herein, discharge pressure is conducted into the pressure control chamber formed between the annular abutment shoulders so as to automatically vary the width of the gap by adjusting the sleeve within the inlet passageway. In this particular embodiment, a control spring is also located between the sleeve and the cover member so as to exert acontinuous bias on the sleeve member.

The injector action improves the fuel velocity distribution in the inlet by accelerating the slow moving particles of fluid in the boundary layer where the velocity of the impeller is at a maximum. In other words, the injector action not only serves to prime the pump, but provides a radial velocity distribution more nearly corresponding with the linear velocities of the impeller vanes.

The improved injector action provided in accordance with the principles of the present invention also permits the operation of the pump at lower fuel inlet heads and effectively prevents cavitation of low-boiling point fluids.

It is an object of the present invention, therefore, to provide an injector apparatus for a pump which will improve pump performance and will increase the range of operation thereof.

Z,8h5,297 Patented Dec. 23, 1958 Another object of the present invention is to provide an injector structure for a pump to provide radial velocity distribution more nearly corresponding with the linear velocities of the impeller vanes.

Yet another object of the present invention is to provide an injector apparatus for a pump which will prevent cavitation of low-boiling point fluids.

A further object of the present invention is to provide an adjustable injector apparatus whereby the degree of injector action may be selectively adjusted by varying the width of an adjuster gap.

Yet another objecto'f the present invention is to provide an automatically adjustable injector action whereby the control of the injector gap will be in a predetermined relationship to a variable pressure condition.

Still another object of the present invention is to provide an injector action for a pump which is located in advance of the seals.

Many other features, advantages and additional objects of the present invention will become manifest to those versed in the art upon making reference to the detailed description which follows and the accompanying sheet of drawings in which a preferred structural embodiment incorporating the principles of the present invention is shown by way of illustrative example.

On the drawings:

Figure 1 is a fragmentary cross-sectional view showing an injector cover for a pump constructed in accordance with the. principles of the present invention and .is taken substantially on line l-l of Figure 2;

Figure 2 is an end elevational view, reduced, of the injector cover of Figure 1;

Figure 3 is a modified embodiment of the present in' vention and shows means for effecting automatic control of the injector gap structure of Figure I.

As shown on the drawings:

A pump incorporating the principles of the present invention is indicated generally by the reference numeral ill and includes a casing 11 formed by a body member 12 and a cover member 13 suitably flanged and bolted together by a plurality of fasteners 14.

A sealing member 16 is located between the cover member 13 and the body member 12.

There is formed in the casing 11 a pumping chamber 17 which is volute in character as is indicated by the discharge portion 13 and in the pumping chamber 1'7 is located a rotatable shrouded impeller it? of the type having a central inlet 2-6 and a plurality of pumping passages 21 communicating with the central inlet and extending radially outwardly to the periphery 22 of the impeller 19.

The impeller 19 is connected to a shaft 23 by suitable fastening means indicated at 24 and is rotatable therewith. It will be understood that the shaft 23 is driven by a suitable power source. A sealing unit 26 is shown mounted in the body member 12 of the casing 11 and provides a seal between the casing ill and the shaft 23.

The impeller 19 includes oppositely directed

hub portions

27 and 28, each of which having aperipherjal hearing surface formed there-on to journal and seal the'impeller lid for rotation in the casing 11, the hub portion 27 engaging a bearing ring 29 carried by the cover member 13 and the hub portion 28 engaging a bearing ring 30 carried by the body member 12 of the casing ll. Itwill be noted that the bearing rings 30 and 2% reduce the leakage of fluid at discharge pressure from the high pres sure area in the discharge portion 18 ofthe pumping chamber 17 back toward the inlet 2i] of the impeller The cover member 13 is provided with an open ended inlet passageway 31 and adjacent one end of the inlet passageway is formed an annular lip 32. In this particular embodiment, the lip 32 tapers convergingly inwardly towards the center of the impeller inlet Ztl and the edges of the lip 32 lie directly adjacent those portions of the impeller vanes which are radially outennost with respect to the inlet 20 of the impeller 19.

The cover member 13 is recessed to provide an annular chamber 33 which will sometimes be referred to hereinafter as a bypass chamber. The chamber 33 lies adjacent the lip 32 and includes an annular opening 34 communicating directly with the open. ended inlet passageway 31 of the cover member 13.

A plurality of circumferentially spaced passageways 36 are formed in the cover member 13 and place the chamber 33 in communication with the discharge portion 18 of the pumping chamber 17 so that the pump discharge may be selectively communicated to the chamber 33 and so that discharge fluid may be recirculated through the passageways 36, the chamber 33 and into the inlet passageway 31.

In this particular embodiment, the inlet passageway 31 is generally cylindrical throughout although of irregular cross-section at various longitudinally spaced points and receives a conformably shaped sleeve member indicated by the reference numeral 37. The sleeve member 37 is provided with an annular end portion 38 convergingly tapered as at 39 to provide a sharp edge 40 cooperating with the lip 32 and forming together therewith an injector gap 41.

Thus, the recirculated discharge fluid emanating from the chamber 33 will be directed in the form of an annular sheath of fluid under high velocity across the lip 32 and into the inlet 20 of the impeller 19. The action of the sheath of fluid serves not only to prime the pump 10, but also provides a radial velocity distribution more nearly corresponding with the linear velocities of the impeller vanes indicated at 42 and communicating with the pumping passageways 21. Furthermore, the injector action increases fuel pressure at the inlet 20 of the impeller 19 and thereby permits the operation of the pump at lower fuel inlet heads without cavitation. It will be understood that cavitation is a particularly serious problem in handling low-boiling point fluids and, accordingly, the arrangement of the injector herein described is highly advantageous.

In order to maintain the width of the injector gap 41 at a selected size, the position of the sleeve 37 is fixed within the inlet passageway 31. In the embodiment of Figure 1,

annular abutment shoulders

43 and 44 are provided on the sleeve member 37 and the cover member 13, respectively, and will engage one another to position the sleeve member 37 in fixed longitudinal alignment within the inlet passageway 31.

In order to selectively enlarge the size of the injector gap 41, the

abutment shoulders

43 and 44 are separated by inserting one or more annular shims indicated at 46.

In the embodiment of Figure 3, the structure of the pump is generally identical with the pump structure of Figure 1, however, means are provided for automatically adjusting the size of the injector gap.

As shown in Figure 3, a cover member 13a has a chamber 33a provided with an inlet passageway 31a and carrying a bearing ring 29a journalling and sealing the hub portion 27a of an impeller 19a. The cover member 13a also includes an annular lip 32a which cooperates with an end portion 38a of a sleeve member 3711 to provide an injector gap 41a arranged to direct a sheath of fluid across the lip 32a and into the central inlet of the impeller 19a.

The inlet passageway 31a is counterbored to provide an annular shoulder 47, the counterbored portion of the inlet passageway 31a receiving a radially extending flange 48 forming an annular abutment shoulder for the sleeve member 37a.

The flange 48 of the sleeve member 37a and the shoulder 47 of the cover member 13a together form op po-site sides of a pressure control chamber 49. By introducing a pressured fluid into the pressure control chamber 49, an axial thrust will be imparted to the sleeve member 37a and will tend to move the sleeve member 37a in one direction so as to increase the width of the injector gap 41a. To conduct such a pressure fluid into the pressure control chamber 49, there is shown a plurality of circumferentially spaced passageways 50 in the cover member 13a placing the pressure control chamber 49 in communication with the chamber 33a. The chamber 33a, in turn, communicates with the pumping chamber 17a through the plurality of circumferentially spaced passageways 36a. To provide a control bias for the sleeve member 37a, a coil spring 51 is bottomed against a retainer ring 52 carried in a recess 53 formed in the inlet passageway 31a and engages the opposite face of the flange 48 on the sleeve member 37a. There is thus exerted a continuous spring bias on the sleeve member 37a tending to close the injector gap 41a.

, By virtue of such arrangement, the position of the sleeve 37a will be variable with the pump discharge pressure and, accordingly, the width of the injector gap 41 will be automatically controlled as a function of the pump discharge pressure.

It will be immediately apparent to those versed in the art that many other structural provisions could be made in effecting an equivalent automatic control of the injector gap width without departing from the spirit and scope of the present invention.

Accordingly, it should be understood that we wish to embody within the scope of the patent warranted hereon all such modifications as reasonably and properly come within the scope of our contribution to the art.

We claim as our invention:

1. A pump comprising a casing having a volute pumping chamber, an outlet, and a center inlet, said casing having a wall forming a passage extending axially away from said center inlet, said wall having an annular by-pass chamber formed therein opening into said passage adjacent said center inlet, an annular lip in-said wall extending radially inwardly into said passage between said by-pass chamber and said center inlet, a sleeve in said passage slidably guided by said wall for axial movement into seating engagement with said lip to close said by-pass chamber and out of seating engagement with said lip to open said by-pass chamber to said center inlet through an annular injector gap formed between said sleeve and said lip, said sleeve having a radially outwardly extending flange formed with a spring seating surface on one side thereof and a motive surface on the opposite side thereof, said motive surface being spaced from an adjoining wall portion of said casing to form a pressure control chamber therewith, a spring bottomed against said flange and against said casing pre-loading said sleeeve into seated engagement with said lip, and passage means formed in said casing between said outlet and said by-pass chamber and said pressure control chamber, pressured 'fluid in said pressure control chamber acting on said motive surface in opposition to said spring to open said annular injector gap and by-pass fluid from said by-pass chamber into said center inlet.

2. A pump comprising a casing having a volute pumping chamber, an outlet, and a center inlet, said casing having a wall forming a passage extending axially away from said center inlet, said wall having an annular by-pass chamber formed therein opening into said passage adjacent said center inlet, an annular lip in said wall extending radially inwardly into said passage between said by-pass chamber and said center inlet, a sleeve in said passage guided by said wall for axial movement into seating engagement with said lip to close said by-pass chamber and out of seating engagement with said lip to open said bypass chamber to said center inlet through an annular injector gap formed between said sleeve and said lip, axially opposite radial abutment surfaces on said sleeve, one of 5 said abutment surfaces forming a spring seating surface and the other of said abutment surfaces forming a motive surface spaced from an adjoining wall portion of said casing to provide a pressure control chamber therewith, a spring bottomed against said spring seating surface and pre-loading said sleeve into engagement with said lip and passage means formed in said casing to conduct pump generated pressure into said by-pass chamber and into said pressure control chamber, whereby pressured fluid in said pressure control chamber acts on said motive surface in opposition to said spring to open said annular injector gap and by-pass fluid from said by-pass chamber into said center inlet;

References Cited in the file of this patent UNITED STATES PATENTS Kime Sept. 28, 1920 Bogdanofi Apr. 29, 1941 Davis Aug. 5, 1941 Hill June 29, 1948 Conery Oct. 28, 1952 FOREIGN PATENTS Germany Nov. 25, 1919 Great Britain Apr. 23, 1943 Great Britain May 10, 1950