US3007513A

US3007513A - Pump assembly for a fuel system

Info

Publication number: US3007513A
Application number: US509529A
Authority: US
Inventors: Leslie L Aspelin
Original assignee: Thompson Ramo Wooldridge Inc
Current assignee: Northrop Grumman Space and Mission Systems Corp
Priority date: 1955-05-19
Filing date: 1955-05-19
Publication date: 1961-11-07
Anticipated expiration: 1978-11-07

Description

Nov. 7, 1961 L. ASPELIN 3,007,513

PUMP ASSEMBLY FOR A FUEL SYSTEM Filed May 19, 1955 s Sheets-Sheet 1 IN V EN TOR.

LESLIE L. ASPELIN AT TO RN YS Nov. 7, 1961 L. ASPELIN 3,007,513

PUMP ASSEMBLY FOR A FUEL SYSTEM Filed May 1.9, 1955 s Sheets-Sheet 2 TJA 68 AFTEB- BUBNEP CONTROL AFTBEBUBNEB CONTROL VALVE 88 87 CONTROL VALVE 89 Menu:

mm avenge FUEL CONTROL um-r INVENTOR.

LESLIE L. ASPE'LI N ATTORNEYS Nov. 7, 1961 1.. L. ASPELIN 3,007,

PUMP ASSEMBLY FOR A FUEL SYSTEM Filed May 19, 1955 3 Sheets-Sheet 3 INVIIN LESLIE L. ASPE TO RN EYS United S tat'es Patent 3,007,513 PUMP ASSEMBLY FOR A FUEL SYSTEM Leslie L. Aspelin, Cleveland Heights, Ohio, assignor to Thompson Ramo Wooldridge Inc., a corporation of Ohio j Filed May 19, 1955, Ser. N0. 50?,529 4 Claims. c1. 15836.4)

This application constitutes a continuation-in-part of my application Serial No. 416,903, filed March l7,' 1954, now US. Patent No. 2,923,245, issued February 2, 1960.

This invention relates generally to fuel systems and more particularly relates to a hydraulic pump of the type including a pair of angularly offset rotorsjou'rnaling reciprocable impellers and operated as either an after burner pump or a main burner pump in the fuel system of jet engines or other aircraft main propulsion means.

Briefly described, the present invention contemplates the provision of a hydraulic pump having a housing with an inlet and an outlet and including end plate means having inlet and outlet portions communicating with the pump inlet and outlet. A pair of rotors are journaled in the housing and have their axes relatively angularly offset with respect to one another; Each rotor has a sealing face communicating alternately with the inlet and outlet portions of the end plate means as the rotor turns.

The pump is further equipped with an impeller having angularly offset arm portions journaled in a corresponding bore of each rotor and reciprocating therein upon rotation of the rotors to alternately produce a suction and a propulsion in the bore when its mouth communicates with the inlet and outlet portions, respectively.

'Each rotor is particularly characterized by the provision of a motive surface which forms together with means including the housing a pressure control chamber. Means for supplying fluid at pump generated pressure to the pressure control chamber are included in the pump, thereby forcing the rotors against the end plate means for sealing and isolating the inlet and outlet portions from one another during pumping operations.

Control means are provided for selectively venting the pressure control chamber to some zone of lower pressure, thereby selectively inactivating the pump by permitting flow communication between the inlet and outlet portions across the sealing faces of the rotors.

In the fuel system of a jet aircraft using an after burner, the pilot requires only selective use of the after burner. Accordingly, to selectively inactivate the pump of the present invention if it is employed as an after burner fuel pump, the pressure in the pressure control chamber is selectively controlled by venting the pressure control chamber back to pump inlet or pressure is permitted to build up in the pressure control chamber if full normal operation of the fuel pump is required.

If the pump of the present invention is employed as a main burner pump in the fuel system of a jet aircraft, the value of pressure in the pressure control chamber is controlled as a function of the burner unit requirements. Furthermore, according to the principles of the present invention the positive displacement pump may be employed in combination with a first stage centrifugal pump and any fuel in excess of burner fuel requirements may be selectively by-passed to a point inter-stage the centrifugal pumping unit and the positive displacement pumping unit, thereby minimizing heat rise and cutting down the amount of work performed upon the fuel.

It is the object of the present invention, therefore, to provide an improved hydraulic pump.

Another object of the present invention is to provide a hydraulic pump of the type having angularly offset relatively rotatable rotors and impellers with control means for selectively inactivating the pump.

3,007,512; Patented Nov. 7, 1961 A further object of the present invention is to, provide a pump of the typeherein disclosed with control means for selectively venting the pressure control chamber to a source of lower pressure, thereby utilizing the value of pressure in the pressure control chamber as a controlling variable in the operation of the pump.

-A further object of the present invention is to provide an improved after burner fuel system for a jet engine aircraft.

Another object of the present invention is to provide an improved main burner fuel system for a jet engine aircraft.

Many other objects, advantages and additional features 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 structural embodiment illustrating the principles of the present invention is shown by way of illustrative example.

On the drawings:

FIGURE 1A is a diagrammatic view of an after burner fuel system for a jet engine aircraft and FIGURE 1 shows a cross sectional'view with parts in elevation of a pump according to the principles of the present invention.

FIGURE 2 is a diagrammatic view illustrating the application of the pump of FIGURE 1 to a main engine fuel system in a jet engine aircraft.

FIGURE 3 is an elevational view of the pump shown in FIGURE 1 indicating the section line of I--'I upon which the plane of the section of FIGURE 1 is taken.

FIGURE 4 is an end elevational view showing the opposite end of the pump of FIGURE 1.

FIGURE 5 is a fragmentary cross sectional view taken substantially on the planeof line VV of FIGURE 1.

FIGURE 6 is a fragmentary cross sectional view taken substantially on the plane of line VI VI of FIGURE 1.

As shown on the drawings:

The hydraulic pump of the present invention is indicated generally by the reference numeral 10 and comprises a housing 11 having an inlet 12 and an outlet 13. The housing 11 includes a cover member 14 fastened to the main body of housing 11 by a plurality of fasteners 16. The end of the cover member 14 is formed to provide a mounting pad 17 to facilitate connection of the inlet 12 and the outlet 13, partly formed by the covermember 14, with suitable conduit connections.

The opposite end of the housing 11 includes a closure member 18 held in firm assembly with the main body of housing 11 by a plurality of fasteners 19. A flange 20 having a plurality of openings 25 is also formed at the end of the housing 11 to facilitate attachment of the pump 10 in a mounting assembly.

"-The cover member 14 and the closure member 18 also constitute end plate means for opposite ends of a bore extending through the housing 11 and including a first bore 21 and a second bore 22, each of which is generally cylindrical in configuration. The axes of the cylindrical bores 21 and 22 are angularly offset with respectto one another and are in intersecting relation so that there is formed in the interior of the housing 11 a plane of intersection between the bores 21 and 22 indicated by reference numeral 23. a p

Within the bore 21 there is provided a rotor 24 which is also cylindrical in configuration, being complementary in size and shape with respect to the bore 21 and journaled for rotation therein. The axis of the rotor 24 is coincident with the axis of the bore 21. Radially outwardly of the axis of the rotor 24 and circumferentially spaced with respect to one another are a plurality of axially extending bores or cylinders or pumping chambers indicated at 26 formed by through openings'extending through the rotor 24. Inwardly' of the pumping chambers 26and coincident of the axis rotor 24 is an enlarged opening 27 in which is received a shaft member 28 having a splined connecting portion 29 extending outwardly of the pump housing 11 for connect-ionto a driving means. The shaft 28 is connected in driving assembly with the rotor 24 as at 30 and is provided with additional journaling support by a bearin g and seal assembly 31 surrounding the shaft 28 at the locale of the closure member 18, W

In the bore 22, there is provided a rotor 32 which is generally cylindrical in configurationbeing complementary in size and shape to the bore 22 and having its rotational axis coincident with the axis of the bore 22. v The rotor 32 is also provided with a corresponding plurality of pumping chambers 33 similarin size and location to the pumping chambers 26 in the rotor 24. A centrally disposed recess 34 is formed in the rotor 32 and bottoms a coil spring 36. One end; of thecoil spring 36 engages against a loading pin 37 reciprocably slidablein the recess 34. The loading pin 37 reciprocates on the axis of the rotor 3 2 and has an action surface 38 which engages an adjoiping action surface 39 formed on a pin portion 40 integral with the rotor 24, which is also located on the corresponding axis of the rotor 24. Thus, the continuous biasing force exerted by the coil spring 36 acts between therotors 24 and 32tending to retain the rotors in separated relation and loaded against the corresponding cover member l4 and closure member 18.

. Referring now more particularly to FIGURES Sand 6 in conjunction with FIG. 1, it will be noted that each of The cover member 14, forexarnple, has an end plate surface indicated at 41 providing a land area which is intersected by a pair of circumferentially extending but spaced apart kidney shaped ports constituting a suction port 42 and a pressureport 43. l

The sealing surface 41 seals and engages against an end face 44 on the end of the rotor 32.

, The closure member 18 is characterized by an end plate sealing surface 46 which is also formed with a land area intersected by circumferentially extending spaced apart kidney shaped ports including a suction port 47 and a pressure port 48. The rotor 24 has an end face which seals and engages against the sealing surface 46 which is indicated at 49. The useof the

ports

47 and 48 insures proper circulation and eliminates possible trapping of stagnant fluid in any portion of the pump. The end face on surface 41 is recessed at 41a (FIGURE 1) and communicates with the pump inlet via a groove 42a to assist in establishing a differential pressure area. At the opposite end, a groove 47a communicates the suction port 47 with the bore 50 to vent the same to inlet.

The closure member 18 also has a centrally disposed opening 50 to pass the shaft 28 and it will be further appreciated that both the closure member 18 and cover member 14 are suitably grooved to receive ring seal members at various places to effect a seal assembly between-the various components of the pump 10.

, As will. be evident from the drawings, the pumping chambers .26 in the

rotor

24 and 33 in the rotor 32 are generally parallel with the corresponding axis of each rotor and each of the pumping chambers includes a mouth portion at the corresponding end face which communicates alternately with the adjoining suction and pressure portions of the end plate sealing surfaces 41 and 46 as the respective rotors turn.

An impeller or piston 51 is provided for each respective pair of pumping

chambers

26 and 33 in the rotors 24 and 32 and has angularly offset arm portions such as an arm portion 51a received in a pumping chamber 26 of the rotor 24 and an arm portion 51b received in a pumping chamof the rotor 32. The angularly offset arms or arm portions 51jafai1d 51b are journaled in the corresponding bores or pumping

chambers

26 and 33 since the impeller and pumping chambers are complementary in size and shape to facilitate relative rotation and reciprocatlon between the parts.

it will be appreciated that the angle of offset of the arm portions 51a and 51b of each impeller 51 corresponds to the angle of offset of the bores 21. and 22 and the axes of rotation of the. rotors 24 and 32. This Tangle offset can be varied anywhere between and Upon rotation of theshaft 28, the rotor 24- will rotate and the im ellers 51 will effect a driving connection between the rotor 24 and the rarer 32 so that both of the rotors will rotate in unison. As will be evident, upon rotation of the rotors 24 and 32 thearm portions 51a 511 of the intpellers 51 will recipr ocatc in thepumping chambers '26 and 33 to alternately producea suction and a propulsion in each respec tive bore when the mouthof the bore communicates w i th the inlet and outlet portions, respec tively of the end platemeans. Each impeller 51 is'hollow and has an opening 52 extending therethrough to com municate the

respective suction ports

42 and 47 and the pressure ports 43 and 48. Thesuction port 42 and the pressure port 43 communicate respectively with the pump inlet 12 and the pump outlet 13 as at 53 and 54, thereby insuring a flovvoffluidupon operation of the pump. Each of the rotors 24 and 32 has a rear face which forms a motive surface indicated at 56 and 57 respectively The motive surfaces 56 and 57 I together with means including the housing 11 form a pressure control chamber 58, a

It will be appreciated that under normal operating con ditions, there is some leakage along the walls ofthe

pump ing chambers

26 and 33 since the impellers fildonot form a perfect seal with the walls along the pumping cha n bers. Thus, fluid at pump generated pressure finds its Way into the pressure control chamber 58 so that a fluid pres surewill -act upcn the motive surfaces 56 and 57 tending to urge the rotors 24 and 32 into good sealing contact with the

endplate sealing surfaces

41 and 46. Since the leakage which occurs along the pumping chamber walls between the pump discharge and the pressure control chamber 58 also exists along the walls of the pumping chamber between the portions of the pump at inlet pres sure and pressure control chamber 58, the value of pressure in the pressure control chamber 58 will be approximately one-half the pressure of the discharge fluid pumped out of the outlet 13. v

There is shown in greatly exaggerated form in FIG. 1 a clearance as at 69 in the bores 21 and 22 to facilitate axial movement of the rotors 24 and 32 with respect to the adjoining en d

plate sealing surfaces

41 and 46. Thus, if the rotors 2 4 and 32 are backed away from the adjoining sealing surfaces, the inlet and outletports 42 and 43 and 4748 will beplaced in flow communication so that the fluid willdir'ectly by-pass through the pump housing without being acted upon and without work being performed thereon. I operating characteristic is advantageously exploited according to the principles of the present invention. The value of pressure in the pressure control chamber 58 is- .selectively controlled so that the respective rotors 24'and. 32 will be pressure loaded against the adjoining end plate: sealing

surfaces

41 and 46 to obtain full capacity discharge: of the pump 10 and by selectively venting the pressure con-- trol chamber 58 to a zone of low pressure, the by-pa'ss flow communication between the inlet and outlet portions across the sealing faces is permitted. Thus, the housing 11v is provided with a boss 61 in which is formed a passage:

62. A nipple fitting 63 is attached to the boss 61 to facilitate connection of a conduit 64 to the passage '62. It will be appreciated that the passage 62 intersects the wall of housing 11 and establishes full flow'communication with the pressure control chamber 58.

In operation, the angled sleeves or impellers 51, together with the various

respective pumping chambers

26 and 33 of the rotors 24 and 32 form expansible chambers which vary involume upon rotation of the rotors 24 and 32. Thus, when the respective bores of the rotor 32 are opposite the

inlet port

42, 12, the expansible chambers-are increasing from a minimum size and fluid from the inlet 12 fills the expanding chambers. When the respective bores of the rotor 32 are oppositethe outlet port 43, 13, the expansible chambers are decreasing in size,;thereby discharging fluid under pressure from the outlet 13.

In FIG. 1A, the conduit 64 is shown as including a control valve 66 whereby the pressure control chamber 58 may be selectively vented through "a conduit 67 to the inlet of the pump 10. This arrangement-is particularly advantageous in a fuel system for the after burner of a jet engine aircraft. For example, as shown in FIG. 1A the burner 68 of an after burner 'unit is shown supplied with fuel by an afterburner control 65 connected by a conduit 69 to the outletil3 of the pump 10. i A manual control 70 accessibleto'the" pilot of the'aircraftis mechanically connected treat 71 to the control valve 66. Since the operator of the aircraft requires operation of the after burner unit-only atselective intervals such as when an additional burst of speed is required or other unusual power requirements are indicated, the operator can activate or inactivate-the pump bycontrolling the value of pressure in the pressure control chamber 58. Specifically, the valve 66 is operated bythe pilot to vent the chamber 58 to pump inlet'12 or to reference the chamber 58 toa source of increased pressure-such as the afterburner control through a connection indicated at 64a.

One of the problems in operation of jet engine aircraft fuel systems is the problem of fuel temperature rise. Fuel requirements vary widely depending upon thefli ght conditions encountered in the operation of the aircraft. Thus, if the aircraft is cruising-at high altitudes a pumping arrangementwhich has great efficiency at maximum power requirements may be supplying far too much fuel with regard to engine requirements and as a consequence, the work done upon the fuel is reflected in the increase in temperature of the fuel, thereby complicating the problems of fuel handling becauseof vapor formation and the like. According to the principles of the present invention, a fuel system is provided as illustrated in the somewhat diagrammatic plumbing diagram of FIG. 2. A burner 80 for a main burner unit of a jet engine aircraft is shown supplied by fuel from a main burnerfuel control unit 85. A fuel cell is indicated at 81 and operates as a source of fuel supply for a first stage centrifugal pumping unit- 82 by supplying fuel thereto via a conduit 181. The pump 10 is shown in series staged relationship with respect to the pump 82, there being an integral common casing connection or conduit shown at 112 so that fuel is supplied to the inlet 12 of the pump 10 at increased pressure from the centrifugal pumping unit 82 and is discharged from the outlet 13 through a conduit 83 connected to the main burner control fuel unit 85. A by-pass line is indicated at 84 and carries fuel supplied to the main burner fuel control unit in excess of burner requirements to a point interstage the centrifugal pumping unit 82 and the pump 10 such as the port 112. Thus, the fuel is returned to a lower pressure zone, but without subjecting the bypassed fluid to excessive pumping work since the point interstage is actually the point of highest pressure ahead of full discharge pressure, thereby minimizing the work performed on the fuel and cutting down on temperature rise within the fuel system.

To further control the operation of the pump 10, it is contemplated according to the claims of the present invention that the discharge of the pump 10 be controlled as a function of engine requirements. To effect that end, the pressure control chamber 58 is connected as at 86 to the main burner fuel control unit, a transfer valve 87 being provided to selectively vary the value of pressure in the pressure control chamber 58 by venting the pressure control chamber 58 to a zone of lower pressure through the conduit 88.

Proper operation of the pump 10 as a function of engine requirements will actually completely eliminate the necessity of by-passin'g fuel through the conduit 84 to a point interstage because if the value of the pressure in the pressure control chamber 58 is reduced in response to a reduction in fuel requirements, a direct by-pass will be established between the inlet and outlet portions of the pump across the sealing surfaces and there will be no wasted hydraulic work performed upon the fuel.

Fully automatic control can be elfected in accordance with the principles of the present invention, therefore, since the valve 87 can be operated by a motor 89 res'ponsive to signals transmitted by the main burner fuel control unit via the conductor means indicated at'90. A manual over-ride 91 mechanically connected as at 92 is also indicated. 1

Those versed in the art will recognize that the terminology used in describing the components of the pump are subject to wide variance. For example, the term impeller has been used to describe the sleeve like pistons or plungers and the term rotor has been used to describe the cylinder member or block. Both components, of course, are characterized by axes which intersect at an angle, in other words, the respective axes are offset from coaxial relation. a a

-Although various 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 contributions to the art.

I claim as my invention:

1. An hydraulic pump comprising a housing having an inlet and an outlet, end plate means at opposite-ends of said housing and each having spaced suction and pressure portions, respectively, a pair of rotors journaled in said housing with their axes relatively angularly offset 'and each rotor having a sealing face engaging an adjoining end plate means, each rotor having at least one bore generally parallel with its corresponding axis and being so arranged that the mouth of its bore atsaid sealing face communicates alternately with the suction 'andpressure portions of the end plate means as the rotor turns, a piston member having hollow angularly offset arms journaled in a corresponding bore of each said rotor and reciprocating therein whereupon rotation of said rotors will alternately produce a suction and a propulsion in the bore when its mouth communicates with the suction and pressure portions, respectively, of the end plate means, said rotors being movable against said end plate means to form a seal at said faces but yieldable under operating pressures acting on the sealing faces of the rotors to break said seal, each rotor having a motive surface forming together with means including said housing a pressure control chamber, means for supplying fluid at pump generated pressure to said pressure control chamber acting on said motive surfaces to force said rotors against said end plate means, thereby sealing and isolating said suction and pressure portions from one another during pumping operation, and control means comprising a valve controlled conduit venting said pressure control chamber to a source of low pressure whereby said rotors will back off from said end plate means due to the pressure acting on the sealing faces of the rotors for selectively inactivating the pump by unloading said rotors and permitting flow communication between said suction and pressure portions across said sealing faces.

2. In a fuel system of the type comprising a burner unit, a source of fuel for said burner unit and a pump for supplying fuel at increased pressure from said source to said burner unit, the improvement comprising an hydraulic pump including a housing having an inlet port connected to said source of fuel and having an outlet port including discharge means leading to said burner unit, said housing including suction and pressure portions at opposite ends thereof, a pair of rotors journaled in said housing with their axes relatively angularly offset, each rotor having at least one bore generally parallel to the axis thereof alternately communicating with the respective inlet and outlet ,portions upon rotation of said rotors, a piston member having hollow angularly offset arms journaled in said bores and reciprocating therein whereupon rotation of said rotors will alternately produce a suction and an expulsion at both of the inlet and outlet portions, respectively, biasing means preloading the rotors against said inletand outlet portions to form a seal at said portions but being yieldable against operating pressures acting onthe sealing faces of said rotors to break said seal, each rotor having a motive surface forming together with said housing a 'pressure control chamber receiving fluid at pump genpressure acting on the sealing faces of the rotors.

3. In a fuel system for a jet engine of the type having a burner, a burner fuel pump comprising a housing having an inlet port and an outlet port and including suction and pressure portions at opposite ends thereof,

a .pair of rotors journaled in said housing with their axes relatively angularly offset, each rotor having at least one bore generally parallel to the axis thereof alternately communicating with said inlet and outlet portions at' the opposite ends upon rotation of said rotors, and a piston member having hollow angularly offset arms journaled in said bores and reciprocating therein whereupon rotation of said rotors will alternately produce a suction and expulsion at both of the inlet and outlet portions,

respectively, said rotors being movable against said inlet and outlet portions to form a seal at said portions and yieldable to operating pressures acting on the sealing faces of said rotors to break said seal, each rotor having a motive surface forming together with said housing a pressure control chamber receiving fluid at pump generated pressure for loading said rotors towards the ends of the housing and valve controlled conduit means between said pressure control chamber and a zone at lower pressure selectively activating and inactivating said pump by venting said pressure control chamber to low pressure, thereby effecting the by-passing of fluid between said suction and pressure portions in the ends of the housing by unloading said rotors due to the pressure acting on the sealing faces of the rotors.

4. In a fuel system of the type comprising a burner unit, a source of fuel for said burner unit and a pump for supplying fuel at increased pressure from said source to said burner unit, the improvement of an hydraulic pump comprising a housing having an inlet connected to'said source of fuel and an outlet including discharge means leading to said burner unit and including suction and pressure portions at opposite ends, a pair of rotors journaled in said housing with their axes relatively angularly ofiset, each rotor having at least one bore generally parallel to the axis thereof alternately communicating with said suction andpressure portion upon rotation of said rotors, an impeller having hollow angularly offset arms journaled in said bores and reciprocating therein upon rotation of said rotors to alternately produce a suction and an expulsion at both of the suction and pressure portions, respectively, each rotor having a motive surface forming together with said housing a pressure control chamber receiving fluid at pump-generated pressure for loading said rotors towards the ends of said housing to form a seal with the ends of said housing, continuous biasing means between said rotors to initially bias said rotors towards the ends of said housing to initially form said seal for starting the pump but being yieldable under operating pressures acting on the sealing faces of the rotors to break said seal, and valve con trolled conduit means in said discharge means between said pressure control chamber and a zone of lower pressure selectively venting said pressure control chamber to low pressure for unloading said rotors due to the pressure acting onthe'sealing faces of the rotors and effecting the by-passing of fluid directly between the suction and pressure portionsin the ends of the housing.

References Cited in the file of this patent UNITED STATES PATENTS 1,048,468 Brun Dec. 24, 1912 1,866,725 Rayfield July 12, 1932 1,996,889 Thomas Apr. 9, 1935 2,284,146 Herman May 26, 1942 2,422,808 Stokes June 24, 1947 2,533,231 Drake et al Dec. 12, 1950 2,713,244 Chandler July 19, 1955 2,782,595 Pauly Feb. 26, 1957 2,939,398 Heiss June 7, 1960