US3008426A

US3008426A - Gear fuel pump

Info

Publication number: US3008426A
Application number: US636772A
Authority: US
Inventors: William V Edwards; Donald L Lorenz; Charles W Rader
Original assignee: Thompson Ramo Wooldridge Inc
Current assignee: Northrop Grumman Space and Mission Systems Corp
Priority date: 1957-01-28
Filing date: 1957-01-28
Publication date: 1961-11-14
Anticipated expiration: 1978-11-14

Description

NOV Y14, 1961 w. v. EDWARDS ETAL 3,008,426

GEAR FUEL PUMP 3 Sheets-Sheet 1 Filed Jan. 28. 1957 EN J @E y wm a Ew IQ N .ww l NN vN 01m/a L. Lorenz L zr/e5 W. Fader Nov. 14., 1961 w. v. EDWARDS ETAL 3,008,426

GEAR FUEL PUMP Filed Jan. 28, 1957 5 Sheets-Sheet 2 Z: L 57. 3 68 Z E z-LD T5 Nov. 14, 1961 w. v. EDWARDS ETAL 3,008,426

GEAR FUEL PUMP Filed Jan. 28, 1957 5 Sheets-Sheet 3 FME/ Fmi-7' E m1-DTE W12/[jam l/ Edwards Dozza/d L. Lorenz hw IWW/@S ggf-27E United States Patent O Ohio Filed Jan. 28, 1957, Ser. No. 636,772 4 Claims. (Cl. 103-126) This invention relates generally to positive displacement and centrifugal pumps and more particularly relates to a mixed flow multiple pump wherein a centrifugal impeller and one or more gear pump units are combined in a single casing, a common driving means being provided with improved frangible coupling means to insure uninterrupted operation of a maximum number of pump units despite failure of one of the pump units and further including improved bushing means for improving the operational characteristics of the pump.

It is an object of the present invention to provide a multiple pump with a safety coupling and driving mechanism having frangible portions to prevent jamming or seizure of the entire pump if one of the pump units fails.

Another object of the present invention is to provide an improved bushing construction for sealing and journaling the gea-rs of the pump.

Another object of the present invention is to provide a multiple pump incorporating both positive displacement and centrifugal stages wherein the respective stages rotate at dilerent speeds and wherein the speed-changing means are mounted in the casing independently of the pumping units.

Many other advantages, features 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 sheets of drawings in which a'preferred embodiment of a gear fuel pump incorporating the features of the present invention is shown by way of illustrative example.

On the drawings:

FIGURE 1 is a cross-sectional view with parts shown in elevat-ion showing a gear fuel pump incorporating the features of the present invention;

FIGURE 2 is an enlarged end elevational view of a fixed bushing provided in the pump of FIGURE l;

FIGURE 3 is a cross-sectional View taken on line III- III of FIGURE 2; y

FIGURE 4 is an end view of the bushing of FIGURE 2 but from the opposite end;

FIGURE 5 is a bottom plan view of the bushing of FIGURES 2, 3 and 4;

FIGURE 6 is an enlarged end elevational view of the pressure-loaded movable bushing of the pump of FIGURE 1;

FIGURE 7 isa cross-sectional View taken generally on line VII-VII of FIGURE 6; and

FIGURE 8 is a view showing the end of the bushing opposite the end of FIGURE 6.

As shown'von the drawings:

The multiple pump of the present invention is indicated generally at 10 and comprises a casing 11 which has an end section 12 connected to the casing 11 by a plurality of fasteners 13. A cover member 14 is connected to the end section 12 by a plurality of fasteners 16.

, At the opposite end of the casing 411, there is provided an end section 17 formed with an inlet 18. A boss 19 projects outwardly from the casing 11 and has formed therein passages 20 connected to pump discharge por-ting to the outlet of the pump.

The casing r11, together with thev end sections 12 and 17,'forrns a pump housing for the multiple pump 10 in which is contained a first centrifugal pumping stage indi- 3,008,426 Patented Nov. 14, 1961 ICC cated generally at 21 in series with a positive-displacement pumping stage consisting of two gear pump units indicated generally at 22 and 23, respectively. Each of the gear pump units '22 and 23 is similar in structural and functional characteristics and like reference numerals will be applied in describing the components to clarify the understanding of the present invention.

Fluid at the inlet 18 is initially pressurized by the centrifugal stage 21 and is supplied for further pressurization to the positive-

displacement stage

22, 23 for subsequent -discharge through the outlet 20.

The cover member 14 is provided 'with usual seal and bearing assembly indicated generally at 24 thereby to support a rotatable driving member indicated at 26 and including a splined shaft portion 27 adapted to be connected to a source of power supply, for example, the accessory drive of an aircraft jet engine if the pump 10 is employed as the fuel pump for the jet engine fuel system.

The driving member 26 extends inwardly of the pump housing and has a thrust ange 28 formed thereon concentrically surrounding a bore 29 which is partially splined as at 30 to couple with the complementary splines formed on the end of a first shaft member formed as a tubular quill shaft and indicated at 31.

The driving member 26 is further provided with a generally cylindrical collar 3-2, the walls of which surround a bore 33 which is, in effect, a counterboreV relative to the bore 29.

The bore 33 has formed in the walls thereof a splined portion indicated at 34 which forms a coupling for the external splines formed on a shaft extension 36 on a driver gear 37 of the gear pump unit 23 inwardly adjacent the driving member 26. l n

The collar 32 is provided with a first reduced shear neck 38 outwardly of the spline connection between the collar 32 and the shaft extension 36. By virtue of such provision, any abnormal force resulting from jamming or seizure of the gear -pump unit 23 will effect torsional yielding of the reduced shear neck 38, thereby interrupting further operation of the gear pump u nit 23.

The driver gear 37 is formed with a 4hollow bore 39 extending therethrough. Thus, the tubular -quill shaft 31 extends inwardly through the bore 39 an-d has formed on the end thereof external splinesv 40 whichmate with complementary internal splines 4formed in the bore 41 4of 4a gear shaft extension 42 on the driver gear 43 ofthe gear pump unit 22.

The driver gear 37 meshes with a driven gear 35 and the driver gear 4K3 meshes with a driven gear 45. K p

The tubular quill shaft 31 is -formed with a second reduced shear neck 44 outwardly of the splined connection between the shafty 31 :and .the driver gear 43. Thus, if any abnormal force results from jamming or seizure -o-f the gear pump unit 22, the shear neck 44 will yield torsionally to interrupt operation of the gear pump unit 22 without affecting or interrupting operation of the other pump components. It should also be noted in this regard that the shear neck 44 isso located as -to be positioned .substantially between the

gear pump units

22 and 23. Thus, any broken pieces adhering to` fthe shaft 31 Will not interfere with the operation of the gear pump unit 23. Moreover, the shaft 311 enjoys a rather large clearance in the bore 39 except -for complementary bearingl portions shown at 46 in FIGURE 1 Iand located between the shaft 3-1 and the shaft extension 47 of the driver gear 37 closest to the driver gear 43 of the gear pump unit 22. Thus, if the coupling portion of .the shaft 31 breaks off at the reduced shear neck 44, the .shaft 31 is supported for rotation at fthe bearing portion A46.

The end section 17 of the pump housing has a bore 418 formed therein in which is received a bearing sleeve 49 for journaliugV-arshaft portion 50 provided on a gear 51. The gear 51 forms pant of a speed proportioning means comprising a gear train rotatable in a gear chamber 52 formed in the end of the casing 11. The gear 51 is further steadied in its rotation by an axial bearing ring 53 supported by a radially inwardly extending strut 54 carnied by the end section 17 of the pump housing.

A bore extends through the lgear 51 and its shaft portion 50 and is provided with splines 56 mating with a complementary plurality of external splines on the end of a second shaft member 57. The second shaft member 57 extends through a hollow bore 58 formed in the driver gear 43 of the gear pump unit 22 and extends into a bore 59 formed in the .tubular shat member 31.

Radially inwardly of the bearing section 46, the shaft 31 is provided with internal splines and the shaft member S7 is provided with external splines as shown at 60, thereby to couple the shaft members 31 and 57 for corotation.

The end section 17 of the pump housing is formed with a volute pumping chamber 61 in which is rotated a centrifugal impeller 62. The impeller 62 is keyed as at 63 and locked as at 64 to a shaft member 66 journaled in a plate-type insert 67 fastened in the en-d sec-tion 17 of the pump housing and providing both radial and axial bearing surfaces. At .the end of the shaft member 66, there is provided a gear 68 meshin-g with the gear 51.

For greatest eiciency, the centrifugal impeller 62 should be rotated at higher speed than the

gear pump units

22 and 23. Accordingly, ythe gear 511 i=s much larger in diameter than the gear 68, thereby permitting the gear train to function as a speed-proportioning mean-s within the gear case S2 and thereby permitting the centrifugal impell-er 62 to rotate in unison with the

gear pump units

22 and 23 but at a much greater rotational speed.

The shaft member 57 is formed with a third reduced shear neck 70 intermediate the spline connection of the shaft 57 with ythe shaft 31. and the spline connection of the shaft 57 with the gear 51. :In this particular embodiment, it will benoted that the reduced shear neck 70 is located outwardly of the shear neck 44. By vlintue of such provision, yabnormal force resulting from jamming or seizure of the centrifugal irnpeller 62 will cause the shear neck 70 to yield torsionally, thereby interrupting the further operation of the impeller 62 without interrupting the continued operation of the

gear pump units

22 and 23.

It will be noted that each of the reduced shear necks including the shear neck 38, the shear neck 44 and the shear neck 70 is in register with the opening in the end of the pump closed by the cover member I14. Thus, separate parts can be conveniently replaced without requiring disassembly of the entire pump since the broken parts can be conveniently removed from .the pump Imerely by removing the cover member 14 at the end of the casing.

As shown on the drawings, a xed or stationary bushing member 71 is provided for each of the gears 35, 37 of the gear pump unit 23 and a similar fixed bushing member 71 is provided fo-r each of the gear members 43, 45 of lthe gear pumlp unit 22.- A retainer ring 72 is attached rto the casing 1-1 by a plurality of fasteners indicated at 73, thereby confining the gear pump units within the pumping cavities fomed within the casing member 1'1 of the pump housing.

Each gear is further associ-ated with a movable pressure-loaded bushing indicated generally at 73. For details of construction of the

bushing members

71 and 73, reference can be advantageously made to FIGURES 2-8.

Referring tirst of all to FIGURES 2-5, it will be noted that the bushing 71 comprises a generally tubular member having a cylindrical body portion 74 and characterized by the formation thereon of a vradially outwardly extending flange 76 at one end. The flange 76 has a front face 77 which forms a sealing face engaging 'the :adjoining side face of a corresponding gear of the

gear pump units

22 and 23, thereby to seal the pumped uid in the gear tooth spaces during the operation of the pump.

The sealing face 77 is generally annular, although each bushing 71 is provided with a chordal section as at 78, thereby to complement 'the generally figure Sashaped pumping cavity in which the gears rotate, adjoining bushings 71 for corresponding driver and driven gears 3S, 37, 43, 45 abutting one another at the chordal section 78 of the flange 76.

As shown in FIGURE 4, the sealing face 77 is particularly characterized -by an inlet relief 79 which provides an open area adjacent the .tooth spaces on the inlet side of the pump to facilitate filling Iof the tooth spaces with inlet uid.

The sealing face 77 is further characterized by an outlet relief 80, as is clearly shown in FIGURES 4 and 5, which is located adjacent the tooth spaces on the outlet side of the pump, thereby to form a trapping relief and to improve the discharge characteristics of the pump.

'Ihe outer periphery of the sealing face 77 is indicated at 81 Iand is concentric to the axis of the bushing 71. For a portion of the outer periphery 81, there is provided a chamfered portion 82 forming a passage intercommunicating the tooth spaces towards the inlet side of the pump. Itwill be noted that the passage formed by the chamfered portion 82 extends into the relief 80, thereby conducting iiuid at discharge lpressure toy the tooth spaces towards the inlet side of the pump; Such provision insures improved iiow characteristics.

At the radially innermost portion of the sealing surface 77, 'there is provided a chamfered relief 83 which operates to remove bearing load from the bushing` 71 at a point immediately adjacent the radially extending sealing face 77. In this regard, it will be noted that a bore concentric to the vaxis of the bushing 71 extends therethrough and the walls of the bore provide abearing surface 84 for journaling the adjoining gear shaft extension` of a corresponding gear of the

gear pump units

22 and 23. 4Extending longitudinally into the bearing surface 84, there is provided a groove 86 which assists in carrying any fluid which may be at the reliefportion 83 into the bearing area, thereby to assist in 1ubricating and cooling the bearing surface 84.

Spaced longitudinally away from the ange 76, there is provided on the bushing 71 a second radially outwardly extending ange 87. 'The outer peripheral surf-ace 88 of the ange 87 is generally concentric tothe axis of the bushing 71 and together with the surface 81 forms spaced beam centers for transmitting bearing support between the bearing surface 84 and the casing 111.

The confronting radi-ally extending, walls of the

anges

76 and 87 are indicated a-t 89 and 90, respectively, and it will be noted that between the walls 8 9 and 90A the bushing is provided with an outer peripheral wall 91 which is generally concentric to the axis of the bushing and which is of considerable lesser diameter than the

peripheral surfaces

81 and 88 of the flanges 76 `and 87.

Between the ange 87 and the end of the bushing 71, there is provided a pilot portion indicated at 92. Thus, the flange -87 has adjacent the pilot portion 92a radially extending wall 93 which, as shown in FIGURE l, engages against either .the end section `12 of the pump housing or against the retainer ring 72. The pilot portion, in turn, as indicated at 92, is received within a corresponding opening of the adjoining pump housing.

`Referring now to FIGURES 6, 7 and 8, it will be noted that the movable bushing 73 is of a generally similar construction to the xed bushing 71 with certain variations resulting from the functional requirements of the movable bushing 73. Thus, the bushing 73 constitutes a generally tubular member having a tubular body portion 96 through which extends a bore forming a cylindrical bearing surface 97 concentric to the bushing axis and particularly characterized by the lformation at the end thereof of a chamfered relief 98 and a longitudinally extending groove 99.

At one end of the tubular body portion 96, there is provided a radially outwardly extending flange 100 having a front sealing face 101 for engaging an adjoining side face of a corresponding ge-ar. The outer periphery 102 of 4the flange 100l is concentric' to the bushing axis except for a chordal portion 103 which abuts against a corresponding chordal portion of an adjoining bushing. For a portion of the periphery, Vthe sealing face 101 is characterized by a chamfered portion 104 forming a passage communicating fluid at discharge pressure from a relief recess 107 on the outlet side of :the pump. The sealing face 101 is further ch-aracterized by an inlet relief 108 located adjacent the tooth spaces on the inlet side of the pump. The reliefs 107 and 108 reduce cavitation and erosion and improve or streamline the flow characteristics of the pump.

On the discharge side of the bushing, there is provided a longitudinally extending aperture 109 which intersects the relief 1107. The purpose of the aperture i109 is to conduct fluid at pump-generated discharge pressure to a motive surface on the bushing indicated at 110 and formed on a second radially outwardly extending flange 111 spaced axially and longitudinally from the flange 100. The flange 111 is also characterized by the provision of an aperture 112, as shown in FIGURE 8. Thus, fluid at discharge pressure is conducted through the aperture 109 into an annular space 113 lying between a radial wall 114 formed on the back of the flange 100 and a radial wall 116 formed on the front of lthe flange 111. From the space 113, the fluid at discharge pressure is conducted through the aperture 112 to the motive surface 110 which is provided by the back face of the flange 111.

The outer peripheral surface of the flange -1'11 is indicated at 117 and is generally concentric to the bushing axis. Thus, the outer peripher-

al surfaces

103 and 117 of the

respective flanges

100 and 111 provide spaced beam support areas by means of which journal Support is provided between the casing 11 and the corresponding gear shaft extension of the

gear pump units

22 and 23.

It will be understood that in connection with both the fixed and the movable bushings, the utilization of separate spaced apart flanges on opposite ends of a large annular space similar to the annular space 113 permits a good journal support to be provided without a great increase in the weight of the bushing. Moreover, there is good force distribution over the spaced beam areas.

Between the radi-

al walls

114 and 116, the bushing is provided with an outer peripheral wall 118 which is of considerable lesser diameter than the

peripheral surfaces

103 and 117 and which is also concentric to the bushing axis.

Between the motive surface 110 of the flange 111 and the end of the bushing 73, there is provided a generally annular shoulder 119 having an outer peripheral surface 120 which is eccentrically offset relative to the bushing axis towards the inlet side of the pump. The outer peripheral surface 120 of the shoulder 119 prescribes the inner peripheral surface of the motive surface 110 and, accordingly, as will be noted upon referring to FIGURE 8, the motive surface 110 is thus graduated in area so that the largest effective area will be directly opposite the discharge side of the pump and unbalanced pressure conditions developed in the pumping cavity will be more evenly balanced.

The eccentric shoulder 119 is further characterized by the provision of an annular groove 121 formed therein and receiving an O-ring or other sealing member 122 for engaging an adjoining portion of the casing provided by a boss 123, as shown in FIGURE 1.

It will be noted that the motive surface is spaced from an adjoining wall of the casing 11, thereby to form together with means including the casing 11 a pressure control chamber 124. The sealing ring 122 operates to isolate the pressure-control chamber 124 Iand the movable bushing 73 will be effectively pressure-loaded into proper sealing relation against the corresponding gear of `the

gear pump units

22 and 23.

The flange 111 is also characterized by the provision of a plurality of circumferentially spaced cylindrical recesses 126, each of which is adapted to receive a small coil spring 127 or other continuous biasing means whereby the movable bushing 73 is initially loaded against the adjoining side faces of the gears.

It will be understood that the flange 111 is also provided with a chordal portion 130 similar to the chordal portion 103 on the flange 100.

Although various minor structural modifications might be suggested by those versed -in the art, it should be understood that we wish to embody within the scope of the patent warranted hereon all suc'h modifications as reasonably and properly come within the scope of our contribution to the art.

We claim as our invention:

l. A pump comprising a casing having an inlet and an outlet, rotary fluid displacement means in said'r casing Vfor moving fluid from the inlet to the outlet and having side faces with journal extensions projecting therefrom, and bushing means in said casing for journaling said rotary fluid displacement means, said bushing means comprising a generally tubular body portion having formed on one end thereof adjacent the rotary fluid displacement means a radially outwardly extending flange, said flange having an end face forming a sealing surface for sealing and engaging against the adjoining side face of said rotary fluid displacement means, said bushing having a second radially outwardly extending flange longitudinally spaced from said first flange axially outwardly of the radial fluid displacement means but axially inwardly of the end of the corresponding journal extension, said first and second flanges having outer peripheral surfaces of the same diameter forming beam support areas, said bushing having a bore extending therethrough on the axis thereof, the walls of said bore forming a bearing surface for journaling the rotary fluid displacement means at said journal extensions, whereby the journal support forces are transmitted through said beam areas to the casing, said second flange havin-g a back face forming a motive surface to load the bushing axially inwardly and being spaced from an adjoining wall of said casing to form a pressure control chamber, both of said flanges having a longitudinally extending aperture formed therein to conduct fluid at pump generated pressure from the outlet side of the pump to said pressure control chamber, said bushing further including a shoulder between the end of said b-ushing and said motive surface on said second flange, said shoulder being peripherally grooved to receive a sealing member, whereby pressure confined behind said second flange will move said bushing in said casing on sm'd beam support areas to l-oad said first flange into sealing relation with the adjoining side face of the rotary fluid displacement means. 2,. A pump comprising a casing having an inlet and a outlet, a pair of meshing gears in said casing for moving fluid from the inlet to the outlet, said gears each having a radial side face and a gear shaft extension projecting from said side face, a movable bushing in said casing on one side of said gears for each said gear, said movable bushing comprising a generally tubular body portion having formed o-n one end thereof adjacent the corresponding gear a radially outwardly extending flange, said flange having `an end face forming a sealing surface for sealing and engaging against the adjoining gear side face, said bushing having a second radially outwardly extending flange longitudinally spaced from said first flange axially outwardly of the corresponding gear but axially inwardly of the end of the corresponding gear shaft extension, said first and second flanges having outer peripheral surfaces of the same diameter forming beam support areas,- said bushing having a bore extending therethrough on the axis thereof, the walls of said bore forming a bearing surf-ace for journaling the corresponding gear shaft extension, whereby the journal support forces are transmitted through said beam areas to the casing, each said bushing having one side of said first and second anges formed as a chordal section, whereby the pair of bushings abut one another at the chordal sections of said flanges, each said second ange having a back face forming a motive surface to load sthe bushing axially inwardly and being spaced from an adjoining wall of said casing to form a pressure control chamber, means forming a passage to conduct fluid at pump generated pressure from the outlet side of the pump to said pressure control chamber, said bushing further including ashoulder between the end of said bushing yand said motive surface on said second flange, said shoulder being peripherally lgrooved to receive a sealing member, whereby pressure confined behind said second ange will move said bushing in said casing on said beam support areas to load said first iilange into sealing relation With the adjoining gear side face.

3. A pump as defined in claim l, said shoulder having an outer peripheral surface prescribing the inner peripheral edge of said motive surface and being eccentrically offset towards the inlet side of the pump, thereby graduating the area of said motive surface to balance the unequal pressure `forces acting on said sealing surface.

4. A pump as defined in claim 2, said shoulder having an outer peripheral surface prescribing the inner peripheral edge of said motive surface and being eccentrically offset towards the inlet side of the pump, thereby graduating the yarea of said motive surface to balance the unequal pressure forces acting on said sealing surface.

References Cited in the le of this patent UN1TED STATES PATENTS 2,625,452 Haller Jan. 13, 1953 2,627,232 Lauck Feb. 3, 1953 2,682,836 Orr July 6, 1954 2,695,566 Compton Nov. 30, 1954 2,696,172 Compton Dec. 7, 19.54 2,696,410 Topanelian Dec. 7, 1954 2,699,724 Murray et al Ian. 18, 1955 2,758,548 Rockwell Au-g. 14, 1956 2,766,700 Klessig Oct. 1 6, 1956 2,767,658 Murray Oct. 23, 1956 2,769,396 Norlin Nov. 6, 1956 2,782,724 Humphreys Feb. 26, 1957 2,823,615 Haberl-and Feb. 18, 1958 2,823,617 Compton ,Feb. 18, 1958 2,824,522 Compton Feb. 25, 1958 2,824,523 Campbell et al. Feb. 25, 1958 2,870,720 Lorenz Ian. 27, 1959 2,887,064 Say May 19, 1959 2,955,536 Gaubatz Oct. 11, 1960 FOREIGN PATENTS 1,060,496 France Nov. 18, 1953