US3518028A - Power reduction of liquid ring pumps - Google Patents

Description

June 30, 1970 R. c. MINICK 3,518,028

POWER REDUCTION OF LIQUID RING PUMPS Filed Jan. 26, 1968 2 Sheets-Sheet 1 INVEATOR. MI A20 C M/V/C TTORMLYS June 30, 1970 R. c. MINICK 3,518,028

POWER REDUCTION OF LIQUID RING PUMPS Filed Jan. 26, 1968 2 Sheets-Sheet 2 INVENTOR. 2/0 0120 C M/v/cK United States Patent O 3,518,028 POWER REDUCTION OF LIQUID RING PUMPS Richard C. Minick, Kirtland, Ohio, assignor t TRW Inc., Cleveland, Ohio, a corporation of Ohio Filed Jan. 26, 1968, Ser. No. 700,860 Int. Cl. F04d 9/00; F04c 15/04 US. Cl. 417-69 6 Claims ABSTRACT OF THE DISCLOSURE A method and means of reducing the power input consumed by the priming pump unit of a fuel booster. The amount of fuel entering into and exiting from the blades of the pumping element of the priming pump when its pumping capability is no longer required is reduced. Specifically, the reduction is accomplished as a function of booster-generated pressure. In a liquid ring pump the pumping element and its pumping chamber ring are relatively moved from a first eccentric position to a second concentric position.

BACKGROUND OF THE INVENTION This disclosure relates generally to centrifugal pumps with built-in self-primers and more specifically to method and means for reducing the shaft power required by the primer of such a combination selectively.

The prior art is exemplified by a well known textbook, Pumps by Kristal and Annett, McGraw-Hill, 1953 wherein the authors describe a centrifugal pump with a self primer built into the unit. The primer pump consists of a positive displacement pump. Insofar as I am aware the applications of built-in self-primers to a pump have been in connection with low speed devices and must continuously operate with fluid available for lubrication.

In accordance with the present invention a so-called liquid ring pump is used to re-prime a high speed centrifugal aircraft fuel booster pump which must be capable of operating dry for extended periods.

It has been discovered in accordance with this invention that the power consumed by the liquid ring pump is mostly a function of the fluid entering and leaving the blades of the pumping element, the liquid ring pump being inherently a very ineflicient device. Thus, it is contemplated that the power consumed by the repriming pump when its pumping capability is no longer required, i.e., after the centrifugal impeller has been adequately primed and is generating pressure, is effected by reducing the amount of fluid entering into and exiting from the blades of the liquid ring pump. While prior art practitioners have shifted the pumping chamber bore wall and the vanes of a rotor to accomplish variations in flow and in pressure, such variations in flow and pressure are of only secondary importance in accordance with the present invention because the primary objective of the present invention is to reduce the power requirements consumed by the liquid ring pump after the main centrifugal high speed pump has been suitably and adequately primed. Thus, a shiftable ring surrounds the bladed rotor of the liquid ring re-priming pump of the present invention. The ring is normally biased by a continuous biasing means into a first eccentric position wherein the re-priming pump operates to draw liquid through the inlet of the fuel booster for priming the main booster pump. As soon as the main booster pump is primed and generates pressure, that pressure is utilized to shift the ring to a second concentric position wherein the amount of fluid entering into and exiting from the blades of the liquid ring pump is significantly reduced.

In an aircraft fuel booster pump, of course, by reducing the total input horsepower in a significant percentage, it is 3,518,028 Patented June 30, 1970 possible to eliminate a corresponding quantum of weight thereby producing a significant overall improvement.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevational view of a pump fuel booster provided in accordance with the principles of the present invention and with parts broken away and shown in crosssection to illustrate additional details of a two-position priming pump arrangement.

FIG. 2 is a fragmentary cross-sectional view of the twoposition prime pump unit of FIG. 1.

FIG. 3 is a cross-sectional view taken on line IIIIII of FIG. 1 and shows the prime pump with the components thereof positioned at a second position wherein the rotor and the shiftable ring of the liquid ring pump are generally concentrically disposed With respect to one another.

FIG. 4 is a cross-sectional view similar to FIG. 3 but showing the components of the liquid ring pump biased to a first eccentrically offset position when the pumping capability of the liquid ring pump is desired and necessary for priming the main centrifugal pump unit.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The general organization of the present invention is most clearly shown in FIG. 1 wherein is illustrated a pump fuel booster 10 which must be capable of operating dry for extended periods. Thus, unlike prior art arrangements heretofore utilizing either vane or slipper-type pumps which are low-speed devices and must continuously operate with fluid available for lubrication, it is contemplated by the present invention that the booster unit 10 provide in a single integral package a main booster pump indicated generally at 11, a re-priming pump shown generally at 12 and a drive motor shown generally at 13.

To provide an enclosure for the entire unit 10, there is utilized a casing means 14 having a coupling pad 16 at one end thereof corresponding to the left end of FIG. 1 in which is formed an inlet 17. The casing 14 forms a convergent throat 19 leading from the inlet 17 to the center inlet 20 of a high speed centrifugal impeller 21 having radially extending pumping passages 22 discharging into a volute 23. The volute also terminates in a mounting pad 24 in which is formed a suitable outlet for discharging the pumping medium for direction to a point of utilization.

The other end of the casing means 14 has a mounting flange 26 formed thereon to which is connected a motor housing 27 by means of a plurality of suitable fasteners 28. It will be appreciated, of course, that the casing means 14 and the motor housing 27 can be made in as many separate parts as may be desired and the twopart arrangement herein shown is merely exemplary. Attached to the end of the motor housing 27 is an electrical receptacle 28 by means of which the driving motor 13 may be energized. In this connection, the motor 13 comprises a rotor 29 having suitable armature means 30 surrounded by suitable stator means 31 and operable to function as the high-speed power source necessary to drive the high-speed impeller 21. A power take-off shaft 32 projects outwardly from the :rotor 29 through the priming pump 12 and has a driving coupling connection with the impeller 21 by means of a driving key 33. The impeller 21, of course, has a central hub portion 34 slotted as at 36 to receive the driving key 33 and a washer 36 together with a nut 37 is used to lock the impeller 21 on the end of the shaft 32. Intermediate the centrifugal element 21 and the priming pump 12, there is provided a seal and thrust assembly located on a reduced diameter portion 32a of the shaft 32. The reduced section 32a leaves a radial shoulder 38. A sealing member 39 rotatable with the shaft 32 has a flange providing a radial face 40 adapted to provide bearing contact with a nosepiece-type bearing member 41 carried in an intermediate passage-forming member shown generally at 42. The seal assembly includes a bearing member providing shaft support for the shaft section 32a and which bearing member is identified at 43. A thrust washer is also shown at 44.

Turning now to FIG. 2, it will be noted that the priming pump 12 has its own subcasing structure and to avoid confusion with the main casing means 14, the selfcontained casing of the priming pump unit 12 may be referred to as a secondary casing herein shown generally at 46. The casing 46 has two side plates, one of the side plates being indicated at 47 and the other at 46; the plate 46 operating as an exhaust porting plate and the plate 47 operating as an inlet porting plate. In'this regard, an inlet port is shown at 48 in the cross section of FIG. 4 and FIG. 3. The exhaust port is designated at 49.

A liner ring 50 is confined between the porting plates 46 and 47 and each respective side of the liner plate 50 has an annular recess 51 for receiving a seal liner shown generally at 52 which seal liners respectively engage the adjoining side faces 53 on the plate 46 and 54 on the plate 47.

An outer housing ring 56 is notched as at 58 on the opposite side thereof to seat the plates 46 and 47.

A recess 59 is formed in the liner ring 50 and bottoms one end of the coil spring 60. The other end of the coil spring 60 engages against a closure member 61 which is fastened to the housing 56 by a plurality of fasteners 62. A passage 63 is formed in the housing 56 through which the coil spring 60 may extend.

Inwardly of the liner 50 there is provided the pumping element of the liquid ring pump. The shaft 32 is keyed as at 63 to a hub 64 of the impeller for the liquid ring pump. Extending radially outwardly are a plurality of vanes or blades 66 disposed in a circumferential row and generally equally spaced from one another. The vane or blades 66 extend outwardly less than the diameter of the liner ring 50. Referring to FIGS. 3 and 4, it will be noted that the internal bore of the liner ring is shown at 67. The housing 56 has an internal recess 68 which is somewhat elliptical in configuration thereby admitting of relative movement of the liner ring 67 under the influence of the coil spring 60 and pump generated pressure.

A plurality of fastening bolts are shown at 69 and extend through the plates 46 and 47 as well as through the housing 56 thereby to retain the various parts of the pump unit 12 in assembly with one another. As shown in FIG. 1 the bolts 69 are connected to the intermediate passage forming member 42 as at 70.

The housing 56 is further provided with a recess 71 communicating through a port 72 formed in the plate 47. The port 72 communicates with passages 73 formed in the intermediate passage forming member 42. The inlet port 48 communicates with passages 74 formed in the intermediate passage forming member 42 which in turn communicates with central openings 76 formed in the hub of the centrifugal impeller 21 and thereby places the inlet port 48 in direct communication with the inlet port 17.

By virtue of the relationship of the pump component shown, it will be appreciated that the pump as shown in FIG. 4 is in a repriming position wherein the liquid ring impeller is disposed in eccentric relation relative to the bore 67 of the liner ring 50. Accordingly, in this position, the liquid ring impeller draws fluid through the port 48, through the passage 74 and the opening 76 communicating with the inlet 17 thereby serving to prime the centrifugal pump impeller of the centrifugal pump 11.

As soon as volute pressure is developed by the centrifugal pump unit 11, pump generated pressure is communicated from the volute 23 through the passage 73 and the port 72 to the recess 71 thereby moving the liner ring 50 to a shifted position against the bias of the 4 spring 60 as shown in FIG. 3. In the position of FIG. 3, the liquid ring impeller is disposed concentrically with respect to the bore 67, thereby reducing the power draw on the constantly rotating shaft 32 when pumping action of the liquid ring pump unit 12 is no longer required.

In an exemplary application for an aircraft fuel booster pump, the total input horsepower can be reduced by about 30% through utilization of the features of the present invention. This amount of power and its corresponding weight is significant in the aircraft industry.

Although minor modifications might be suggested by those versed in the art, it should be understood that I wish to embody within the scope of the patent warranted hereon all such modifications as reasonably and properly come within the scope of my contribution to the art.

I claim as my invention:

1. A pump fuel booster comprising a main casing having formed therein a volute with a center inlet and a peripheral outlet for delivering fuel under increased pressure, means including said casing extending away from said volute to form a reprime pump housing and a driving motor housing having a return port formed therein,

a driving motor in said driving motor housing having a power output shaft extending through said reprime pump housing,

a high speed centrifugal impeller having a driven coupling connection with said output shaft for rotation of said impeller in said volute,

a cylindrically shaped secondary casing in said reprime pump housing having an inlet and an outlet and comprising a ring outwardly of said inlet and outlet and normally spring biased to a relatively eccentric position with respect to the axis of such shaft,

a liquid ring impeller coupled to such shaft and rotatable in said cylindrically shaped secondary casing, said main casing and said centrifugal impeller having axially extending priming passages formed therein and placing said center inlet in communication with said inlet of said secondary casing,

and control passage means in said main casing extending between said volute and the interior of said secondary casing exteriorally of said ring,

whereupon volute pressure will move said ring to a second concentric position when said centrifugal impeller is primed to reduce the power consumed by the priming pump, but returning said ring to its first eccentric position for repriming whenever volute pressure is correspondingly reduced.

2. In a fuel pump, a high speed centrifugal pump including a rotatable impeller having axial priming openings extending therethrough,

a repriming pump,

and a common motor for driving both of said pumps,

said repriming pump having relatively movable casing and rotary fixed vane fluid displacement means to reduce the amount of fuel entering and exiting the rotary fluid displacement means,

and control means for effecting said relative movement when said rotatable impeller is primed and the pumping capability of the repriming pump is no longer needed,

thereby reducing the power input consumed by the repriming pump.

3. In a fuel pump as defined in claim 2,

said repriming pump comprising a liquid ring pump wherein said rotary fluid displacement means comprises a pumping element consisting of a hub having an annular row of radially extending blades,

since said casing comprises a circular inner ring of larger inner diameter than the outer diameter of said pumping element,

said casing further comprising a stationary outer portion having a recess in which said ring is confined for movement transversely of the pumping element axis of rotation, and spring means between said inner ring and said outer portion biasing said ring to a first eccentrically offset position relative to said axis of rotation. 4. In a fuel pump as defined in claim 3, said control means comprising passage means interconnecting the outlet side of said centrifugal pump with said casing outwardly of said inner ring, thereby to pressure load the ring to a second concentrically disposed position relative to said axis of rotation Whenever the centrifugal impeller is primed and generating pressure to overcome said spring bias.

5. In a fuel pump as defined in claim 4, said casing including spaced side plates having inlet and outlet openings formed therein respectively in- Wardly of said ring. 6. In a fuel pump as defined in claim 5,

said ring having annular sealing members slidingly engaging said side plates.

References Cited UNITED STATES IPATENTS FOREIGN PATENTS 12/ 1957 Germany.

8/ 1955 Great Britain. 1/ 1959 Great Britain.

HENRY F. RADUAZO, Primary Examiner U.S. Cl. X.R.

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