Title of Invention

VARIABLE DISPLACEMENT PUMP HAVING A ROTATING CAM RING

Abstract Vane pump (10) mechanical losses are reduced by removing vane friction losses and replacing them with lower magnitude journal bearing fluid film viscous drag losses. A freely rotating cam ring (70) is supported by a journal bearing (80). A relatively low sliding velocity is imposed between the cam ring and the vanes (26). This permits the use of less expensive and less brittle materials in the pump by allowing the pump to operate at much higher speeds without concern for exceeding vane tip velocity limits.
Full Text

VAmABUlDISPlACIMlI^T PUMP HAVING A ROTATING CAMBING

[0004] When used tilths jet engine emriiomnent, for example, vane pumps use
materials that arc of geoer^
and loading factors eacoimteted by these vane pumps. Parts tnamifectoied firoia these
materials generally w« more to produce ai^ For example,
tungsten carbide is widely used as a preferred material for vase pomp component used in
l

jet engines. Tungsten carbide is a vary hard material that fmdsp^
the vane, cam ring, and side plates. However, hmgstocaibide is approx^
one-half (2V4) times the cost of steel, for example, and any flaw enroverstress can result in
cracking and associated problems. In addition, the ratio of the weight of tungsten carbide
relative to steel is j^roximatdy 1,86 so tb^
forthese types of applications. Thus, although the genially high durability and wear
resistance make tungsten carbide suitable for the high velocity and loading factors in vane
pumps, die weight, cost, and high britdoiess associated therewith results in a substantial
increase in overall cost
[0005] Even "qing special materials such as tungsten carbide, current vane pumps
are somewhat limited in turning speed. The limit relates to the high vane tip sliding
velocity relative to the cam ring. Even with tungsten carbide widely used in the vane
pump, high speed pump operation over 12,000 RPM is extremely difficult
{0006] Improvod efficiencies in the pump are extremdy desirable, and increased
efficicntiesinooqjuncti^
pump for other applications are desired.
[0007] An improved gas turbine fbdpon^exhibMi^incwsQfledef^ reliability is provided by the preset
[0008] More particularly, {he gas turbine fuel praxp includes a hcnising having a
pump chamber and an inlet and outlet in fluid communication with the chamber. A rotor
is received in the pump chamber and a cam member surrounds the rotor and is fiedy
rotatable relative to the bousing.
[0009] A journal bearing is interposed between the cam member and the housing
for reducing mechanical losses during operation of the pump.
[0010] The journal bearing is a continuous annular passage defined between the
cam member and the housing.

[0011] The rotor iadudos ctrcun^
in contact with the cam member.
[0012] The pump further includes a cam sleeve pivotally secured within the
housing to selectively vary the eccentricity between the cam member and the rotor.
[0013] The gas turbine fuel pump exhibits dramatically improved efficiencies
over conventional vaae pumps that do not employ the freely rotating cam member,
[0014] The fuel pump also exhibits improved reliability ax a reduced cost since
selected components can be formed of a reasonably disable, less expensive material.
[0015] The improved efficiencies also permit the pump to be smaller and more
compact which is particularly useful for selected applications where size is a critical
feature,
[0016] Still other benefits and advantages of the invention will become apparent to
one skilled in the art upon reading the Mowing detailed description.
Brief Description of the Drawings
i
(MIT] Figure 1 is an exploded perspective view of a preferred embodiment of the
fluid pump.
[§018] Figure2isacros^sectioBalWewt 1.
[0019] Figure 3 is a longitudinal cross-sectional view through the assembled
pump-
[0020] Figure 4 is a cross-sectional view similar to Figure 2 illustrating a variable
displacement pump wife. Ac support riag located ma second position.
Detailed Datcription of the Preferred EmMiffifim
[0021] Aa shown in the Figures, a pump assembly 10 includes a housing 12
having a ptnnp chamber 14 defined therein. Rotatably received in the chamber is a rotor 20 secured to a shaft 22 forrotatiag the tutor withk the chamber. Peripherally or circqniferentiaUy^acedabom the rotor are operatively receive blades or vanes 26 having outer laldM tips that cxtc^£rom^

periphery of the rotor. Tto vanes may vary innumbcr, for exaojple, trine (9) vanes are shown in flie cmbodimcflt of Figure ^
without departing fiorn the scope and intent ofthe present invention. As is perhaps best illustrated in Figure 2, the rotational axis of ihe shaft 22 and rotor 20 is referenced by numeral 30, Selected vanes (right-hand vanes diown in Figure 2) do not extend outwardly fiom the periphery of the rotor to as great an etfent as the remaining vanes (left-hand vanes in Figure 2) as the rotor rotates withfo the housing chamber. Pumping chambers are defined between each of die vanesas the vanes rotate in die pump chamber with the rotor and provide positive displacement of the fluid
(0022] With continued reference to Figure 2, a spacer ring 40 is rigidly secured in
the housing and received around the rotor at a location spaced adjacent the inner wall of the housing chamber. Thcspacer ring has a fist or planar cam rolling suifece42and receives an anti-rotation pin 44. The pin pivotally receives a cam sleeve 50 that is non-rutatably received around the rotor. First and second lobes or actuating surfaces 52,54 are provided on the sleeve, typically at a location opposite the anti-rotation pin. The lobes cooperate with first and second actuator asvmbKes 56,58 to define means fa altering a position ofthe cam sleeve 50. Tbe altering means selectively alter the stroke or displacement of the pomp in a manner wefl known in the art For example, each actuator assembly includes a jiston 60f biasing means such as spring 62, and a closure member 64 so that in response to pressure applied to a rear fece of the pistons, actuating lobes ofthe cam sleeve are selectively moved. This selective actuation results in rolling movement of the cam sleeve along a generally planar or fiat siirfiwe (6 located along an Inner surfice ofthe spacer ring adjacent on the pin 44. It is desirable that the cam sleeve undergo a linear translation of the oeotexpoint, rather than arcuate movement, to limit pressure pulsations that may otherwise arise in seal zones ofthe assembly. In tins manner, die center of lie cam sleeve is selectively ofi&et from die rotational axis 30 of die shaft and rotor when one of the actuator assemblies is actuated and moves the cam sleeve (Figure 2), Other details ofthe cam sleeve, actuating surface, and actuating assemblies are

generally wellknown to those akfflcdmtheartaot^
deemed unnecessary.
[0023J Received within the cam sleeve is a rotating cam member or ring 70
haying a smooth, toner peripheral wall 72 that is contacted by the outer tips of the individual vanes 26 extending fom the rotor. An outer, smooth peripheral wall 74 of the cam ring is configured for free rotation within the cam sleeve SO. More particularly, a journal bearing 80 supports the totaling cam ring 70 within the sleeve. The journal bearing is filled with the pump fluid, here jet fiieU and defines a hydrostatic or hydrodynamic, or a hybrid hydrostatic/hydrodynamic beating. The frictional forces developed between the outer tips of the vanes and fce rotating cam ring 70 xesult in a cam ring that rotates at approximately the same speed as the rotor, although the cam ring is free to rotate relative to the rotor since there is no structural cornponciitintiMlockingt^ cam ring for rotation with the rotor. It will be appreciated that the ring rotates slightly less than the speed of the rotor, or even slightly greater than the speed of the rotor, bat duetothesuppcHrt/operatimmthefl
lower magnitude viscous drag. The low viscous drag ofthe cam ring substitutes ibr the high mechanical losses exhibited by known vane jmmpa that result from the vane frictional losses contacting the surrounding stationary ring. The drag forces resulting from contact of the vanes with the cam ring are converted directly into mechanical losses thatieduoe the pumps overall efficiency. The cam ring is supported solely by the journal bearing 80 within the cam sleeve. The journal bearing is a continuous passage. That is, there is no interconnecting structural component such as roller bearings, pins, or the like that would adversely impact on tie benefits obtained by 4e low viscous drag of tfie cam ring. For example, flooded ball bearings would not «hibk the improved efficiencies offered by the journal bearing* particularly a journal bearing that advantageously uses the pump fhrid as the fluid bearing.
[0024} In prior applications these mechanical drag losses can far exceed the
Tnechroiral power to pump the fluid in many operating regimes of the jet ang™ft fuel pump. As a Tamil-, thfflft w»« A TftqnVrfi i»«» t\f mqf»riflfo ft^^mig highrr durability and

wear resistance because ofthe high velocity The
material weight and mamifacturing costs were
suffer from highbritileness. The turning speed of those pfiimpswas also limited due to
the high vane sliding velocities relative to the cam ring. Even when using special
materials such as tungsten carbide, high speed pump operation, e.g„ over 12,000 RPM,
was extremely difficult
[0025] These mechanical losses resulting from friction between the vane and cam
ring are replaced in the present invention with muA lower magnhudc viscous drag losses.
This results from the ability of the cam ring to rotate with the rotor vanes. A relatively
low sliding velocity between the cam ring and vanes results, and allows the manufacturer
to use less expensive, less brittle materials in the pump. This provides for increased
reliability and permits the pump to be operated at much higher speeds without the
concern for exceeding tip velocity limits, hi turn, higher operating speeds result in
smaller displacements required fa achieving a given flow. In other words, a smaller,
more compact pump can provide similar flow results as a prior larger pump. The pump
will also have an extended range of application for various vane pump mechanisms.
109261 Figure 3 more particularly ilta^
rotOT for providing an inlet and outlet to the pump chamber. Fnst and second plates 90,
92 have openings 94* 96, respectively, Enecgy is imparted to the fluid by ta
vanes. Jet &ei,fbr example, is pumped to a desi^
pressure.
[00271 A* shown in Figure 4, neither of the actuating assemblies is pressurized so
that die cam sleeve is not pivoted to vary die stroke of the vaoe pump, Thatis»lfaisno flow position of Figure 4 can be compared to Figure 2 where the cam sleeve 50 is pivoted about die pin 44 so flat a close clearance is defined between the cam sleeve and the spacer ring 40 along the left-hand quadrants of the pump as illustrated in (he Figure* This provides for variable displacement capabilities to a maimer adaeved by id position of die cam sleeve;

(0028] In the prefixed arrangement, the vanes arc stiU manufactured ftom a
durable, haid material such as tungsten carbide. The cam ring and side plates, though, are
alternately formed of alow cost, durable material such as steel to reduce the weight and
manufacturing costs, and allow greater reliability. Ofcourse, it will be realized that if
desired, all of the components can still be formed of more expensive durable materials
such as timgpten carbide anil still achieve substantial efficiency benefits over prior
arrangements. By using the jet fuel as the fluid that forms the journal bearing, the
benefits of tungsten carbide for selected components and steel for other components of
the pump assembly are used to advantage This is to be contrasted with using oil or
similar hydraulic fluids as the journal bearing fluid where it would be necessary for all of
the jet ftael components to be formed from steel, thus eliminating the opportunity to
obtain tie benefits offered by using tungsten catbide.
[0029] The invention has been described with reference to ihe preferred
embodiments. Obviously, modifications and alterations will occur to others upon reading and undastanding the preceding detailed description. It is intended that the invention be construed as including all such modifications and altciaticms in so far as they come within the scope of the appended claims or the equivalents thereof.





Waving thus described the present invention, is now claimed:
1. A variable displacement gas turbine fuel pump comprising:
a housing having a pump chamber, and an inlet and outlet in fluid communication with the pump chamber;
a rotor received in the pump chamber;
a cam member surrounding the rotor and freely rotating relative to the housing;
a cam sleeve radially interposed between the cam member and the housing;
means for altering a position of the cam sleeve in the housing to selectively vary pump output; and
a journal bearing interposed between the cam member and the cam sleeve for reducing mechanical losses during operation of the pump.
2. The fuel pump of clami 1 wherein the cam member has a smooth, inner peripheral wal* that allows the rotor to rotate freely relative to the cam member.
3. The fuel pump of claim I wherein the journal bearing is a continuous annular passage between the cam member and the cam sleeve.
4. The fuel pump of claim I further comprising circumferentially spaced vanes operacvely associated with the rotor.
5. The fuel pump of claim 1 further comprising a cam sleeve radially
; 'interposed between the cam member and the housing.
6. The fuel pump of claim 5 further comprising means for altering a position of the cam sleeve in the housing to selectively vary pump output.
7. The fuel pump of claim 1 further comprising a spacer ring radially interposed between the cam sleeve and the housing.

8. The fuel pump of claim 7 wherein, the cam sleeve is pivotally secured to the '.spacer ring to selectively vary an offset between the cam member and the rotor.
9. The fuel pump of claim 1 wherein the journal bearing is a hydrostatic bearing.
10. The fuel pump of claim 1 wherein the journal bearing is a nydrodynaznic bearing.
11. The fuel pump of claim 1 wherein the journal bearing is a hybrid kydrosiatic/hydrodynamic bearing,
12. A variable displacement gas turbine fuel pump for supplying jet fuel from a supply to a set of downstream nozzles, the gas turbine fuel pump comprising:
a housing having a fuel inlet and a fuel outlet in operative communication with a pump chamber,
a rotor received in the pump chamber, the rotor having plural vanes that segregate (he pump chamber into individual pump chamber portions;
a cam ring received around the rotor having radially inner and outer surfaces the inner surface slidingly engaging the vanes;
a cam sleeve radially interposed between the cam ring and the housing;
means for altering a position of die cam sleeve in the housing to selectively vary pump output; and
a cam journal bearing surrounding the cam ring in communication with tie fuel inlet whereby jet fuel serves as the fluid film in the journal bearing for the • cam rin.5.
13. The foci pump of claim 12 wherein the journal bearing is a bydrodynamic bearing.
14. Hie fuel pump of claim 12 wherein the journal bearing is a hydrostatic bearing.

15. The fuel pump of claim 12 wherein the journal bearing is a hybrid lydxosvatic/hydrodynamic hearing.
16. The fuel pump of claim 12 wherein a center of the cam sleeve enclosing the cam ring is selectively offset from a rotational axis of the rotor.
17. The fuel pump of claim 12 wherein the journal bearing is a continuous annular passage between the cam ring and the cam sleeve.
18. The fuel pump of claim 12 further comprising circumferentially spaced vanes cperatively associated with the rotor.
19. The fuel pump of claim 12 further comprising a cam sleeve radially intcrpo scd between the cam ring and the housing.
20. The fuel pump of claim 19 further comprising means for altering a :3csiticn of the cam sleeve in the housing to selectively vary pump output
21. The fiiel pump of claim 19 further comprising a spacer ring radially interposed between the cam sleeve and the housing.
22. The fuel pump of claim 21 wherein the cam sleeve is pivotally secured to the spacer ring to selectively vary the eccentricity between the cam ring and the rotor.
4
23. The fuel pump of claim 12 wherein the vanes are formed of tungsten carbide.
24. The fuel pump of claim 12 wherein the cam ring is formed of a low cost, durable material.
25. A method of operating a gas turbine fuel pump that includes a housing having a pump chamber that receives a rotor therein and a cam member surrounding

the rotor, a cam sleeve surrounding the cam member and a spacer ring disposed between the cam sleeve and the housing, the method comprising the steps of:
supporting the cam member via a journal bearing in the housing; allowing the rotor to rotate freely relative to the cam member; and linearly translating a centerpoint of the cam sleeve to limit pressure pulsations in seal zones of the assembly.
26. The fuel pump of claim 8 wherein the spacer ring includes a generally planar surface that allows a centerpoint of the cam sleeve to linearly translate.
27. The fuel pump of claim 8 wherein the spacer ring includes a generally planar :iurface along an inner surface thereof upon which the cam sleeve rolls in response to actuation of the altering means.
28. The fiielpump of claim 1 further comprising a spacer ring radially interposed between the cam sleeve and the housing, and an anti-rotation pin interconnecting die spacer ring and the cam sleeve.
29. The fuel pump of claim 28 wherein the spacer ring includes a generally planar surface along an inner surface thereof adjacent die anti-rotation pin.
30. The method of claim 29 wherein the spacer ring includes generally planar surfaces on opposite sides of the ami-rotation pin.
31. The fuel pump of claim 12 further comprising a spacer ring radially
A interposed between the cam sleeve and the housing, and an anti-rotation pin
intercotnecting the spacer ring and the cam sleeve.
32. The fuel pump of claim 31 wherein die spacer ring includes a generally
planar surface along an inner surface thereof adjacent die anti-rotation pin upon which
die cam sleeve rolls in response to actuation of the altering means.

A variable displacement gas turbine substantially as herein described with reference to the accompanying drawings.


Documents:

1570-chenp-2003 abstract grand.pdf

1570-chenp-2003 abstract.jpg

1570-chenp-2003 abstract.pdf

1570-chenp-2003 claims grand.pdf

1570-chenp-2003 description (complete) grand.pdf

1570-chenp-2003 drawings grand.pdf

1570-chenp-2003-claims.pdf

1570-chenp-2003-correspondnece-others.pdf

1570-chenp-2003-correspondnece-po.pdf

1570-chenp-2003-description(complete).pdf

1570-chenp-2003-drawings.pdf

1570-chenp-2003-form 1.pdf

1570-chenp-2003-form 18.pdf

1570-chenp-2003-form 3.pdf

1570-chenp-2003-form 5.pdf

1570-chenp-2003-pct.pdf


Patent Number 227454
Indian Patent Application Number 1570/CHENP/2003
PG Journal Number 10/2009
Publication Date 06-Mar-2009
Grant Date 07-Jan-2009
Date of Filing 06-Oct-2003
Name of Patentee ARGO-TECH CORPORATION
Applicant Address 23555 EUCLID AVENUE, CLEVELAND, OH 44117-1795,
Inventors:
# Inventor's Name Inventor's Address
1 CLEMENTS, MARTIN, A 6581 DEVONSHIRE DRIVE, NORTH ROYALTON, OH 44133,
2 HANSEN, LOWELL, D 380 WOODSIDE DRIVE, SAGAMORE HILLS, OH 44067,
PCT International Classification Number F04C2/344
PCT International Application Number PCT/US02/09298
PCT International Filing date 2002-03-27
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 60/281,634 2001-04-05 U.S.A.