US2955541A

US2955541A - Variable flow pump

Info

Publication number: US2955541A
Application number: US662781A
Authority: US
Inventors: Cecil L Moore
Original assignee: Engineering & Res Lab Service
Current assignee: Engineering & Res Lab Service; Engineering & Research Lab Service Co
Priority date: 1957-05-31
Filing date: 1957-05-31
Publication date: 1960-10-11
Anticipated expiration: 1977-10-11

Description

Oct. 11, 1960 c. L. MOORE 2,955,541

VARIABLE FLOW PUMP Filed May 51, 1957 u ww P. R w M HT. 5 m 4 M, 1 m 1 Z PW 3/ w m L 1 H W. 3 m n n z M H 62 M 8 5 a mm w a m m Mn 1 g, z 7/ wk m 3 y fl fl u um United States Patent FLQWPUW i e l L-"M or "Indi nap lis 'ludassis 't l ugm' r- & Research Lab. ServiceCd Q Indianapolis, Ind-Q a "company- 01f lndiana @FiledfMay e1, 1951m 1N0. ream SElaims. or. 103-120 ;-.invention relatessgtznerallyatordisplacement type mumps, :and particularly to 33.; pump :of -whieh tcan :deliver =;-a zvariablevolumetric flow sate-constant pressure.

lnithetpl mpingiofzhydraulic fluidsitoesupplyrfiuidennder pressure :to Ehydraulic lmotors =20! .other rhydraulic- :com- ;ponents, this advantageous zto sp'mvi'de forwarying the -.volumetric:flow of :thelfluid without staying-stile spressure 10f sthe :fluid :supplied :to zthethydraulic .eomponent. The ipreferrediembodiment :of the :present invention provides :11 {8w tpump :in which the igearstmay be vvariably disiplaced, :relaitive do ;each :;other, :to :thereby :the none :.of mesheof :the :gearzteeth. ithe -gaIS al e relatively epositioned, athe vspace :hetweenuhetunmeshed teeth 'of the .gears :is' simultaneously plugged tor illed by means of (members :hav-ing appropriately ishaped fifingersextending therefrom. a

lntthe preferred=embodimentrof the invent'ion', the relaitive positioning lot "the gears and the plugging of tlie space :between ithe ;.unmeshed. gear teeth is accomplished in response to variations in "the pump outlet pressure. Because =the zone:.o"f meshiofithe=gears (and oonse'quently tthe 'volumetric delivery of :the 1 pump) is varied inversely with the pump outlet pressure, the pump tends t o. hold a :oonstant outlet pressure under warying demands. This LChiil'fiCtCfiStiC of -the pump makes 'it particularly useful in :supplying ffluid pressure :to a =variable speed ehydraulic motorwhichoperatesatconstantapressure.

JA ifutther 1 object-of the :present invention is toproviile -;a variable idelivery -pump having a volumetric-delivery irelatively independent of the speed "of rotation-of the pump :driving means.

- A further object-is =to =provideca pumpwvhich can-"(le- -liver fluid at a constant pressure under svariable'demanil, the delivery of the pump being independent of :the rota- :tional speed of the pump'driving means.

A further object is to provide a pump having ;a*volutinetric delivery which -is"variable in response to a control pressure.

I'he full 'nature of the invention will be understood sfrom the accompanying drawings and the -following de- :scription and claims:

:Fig. 1 ies perspective view of the apparatus embodying the present invention, withportions 'brokenawayrto illustrate the-internal arrangement. Fig. 2is 'a sidesectional'view of the apparatus shown in Fig. 1.

Fig. "3 is a *view simi1ar -*to Fig. ibut illustrating 1 the *parts' in different relative position.

Referring to the drawings, an elongated :hous'ing "10 has end-plates "11 secured thereto by *means of bolts "12. A drive shaft 13 extends through the housing andis iournaled in-bearings '14 which are fixed inthe end plates by-meansof pins 1 6. splined tto the-shaft 13 is -a-d rive -:=gear 17 having teeth 18 thereon. may best "beseen in Fi'g. 1,4118 gear -P1 has appreciable length along its axis f-rotation. s

shown :in Fig. 2, theiinternalsurface of the axial opening'Lthrough-theigear '17 is ispline'd at 519, thisisplined area .cooperatingflwith an appropriately rsplined area :21 on ithe' shaft' j13ito permitrotation of the gear by the dfiViMt.

.iA'ztubular stationary member 22 :extends through the lower IEPOItiQH of zthe:housings:paralle1xto the i drive shaft. Member 22 issupported by the end plates and is. locked dherein'ebwmeans got a ;pin"23. Anidlerigear 24 is Ziournaleddor rotation :onzthe :tubularmemberby means of'bushings 26. sfl heaidlerxgearacarries teeth :27 thereon adapted to. mesh with theateeth of the driving gear. From the foregoing :it will be iunderstood that the K drive. gear is .rotated :by the .drive shaft '13, but is: capable'of nbeing axially .dis'placedton the shaft :because of its :splined connection thereto, ;and that the .idler .egear is free to rotate :about athettubular :member 22, but can :be axially dis- :piaced alongthe tubular member.

The aneans i for axially displacing [the :gears, thereby tvaryin g the :"zone of mesh therebetween, comprises a ram, .orapistonvZShaving a central opening therethrough 123C- commodating :the drive shaft. The outer end of .Ithe ;piston terminates :short .of the housing end plate :to pro- .videacavity or pressurechamber 29 for the purpose of which 'willbe subsequently explained. :Beneath and adiaeent :the piston 28 :is -a member 31 journalled for rotation on the :tubular member :22-and having ;multiple-.ex tendingifingers 32. ;As may :best be s'een'in Fig. i-lythe :fingers are appropriately :shaped so *that :they fit snugly within the space-between :the teeth @ofrthe idler gear :24. .An axial .cavity within -:-the zmeniber r31 accommodates a compression spring v 33 whichextends between awshoulder iformediat :the-outer =-end of the member 31 x and a -washer .:3,4 which in turn bears againsttthe 'idler gear. The :nonrotating piston 28 and the rotating member 31 areq'oined {or =-unitary --movement along the drive shaft and tubular v.memberglziy"means of -a;ring-shaped'key 36 which extends .;into:;a-l eyway-or annular groove '{formed in themember 1-3-1 and acooperating-retainer ring 37 threaded upon the reduced outer end'of ?the member. The piston 28 and the member .31 are ;thus adapted tomove in unison with in the housing, the limit of their leftward movement (as viewed in -.Fig. .2.) being -.est-ablished by the stop or spacer 38. a

.At the opposite tendof .the zhousingithere is accommoedated on :the vtubular member -a piston 39, similar to the pistonlS, and *a pressure chamber -41, -similar to cham- :ber -29,-:is provided-at .its outer end. Adjacent to and above the piston 39 is-a rotatable member 42 -journalled mm thedrive shaft and similar .to the: member 31. 'Member 42 carries extending fingers 43 adapted to fit snugly :within .the space between .the teeth .18 -of the drive 1 gear. ,A'eompressionspring 44, similar *to spring 33, extends between .the end of the member 42 and the gear 17. A retainer ring 46 threaded on the=end of member 42;pro- .vides akeyway for anannular-key 4 8 which serves to permit \the .piston 39 and the member 42 to be moved axially in unison, but allows member "42 to be rotated tupon .the drive shaft while piston 39 is non-rotatably mounted-onthe tubular -member22.

The -,pump assembly a above describedhas opposed -fluid inlet ian d outletopenings through -the housing, only the outletiopening 49 being shown. A fluid passage -51 has communication with the outlet topening and at 5 2 and 53 with the

chambers

29 and 41, respectively.

In operation, with the drive-shaft rotatingata given speed, and with the-zone of meshof thegear teeth extending as'aindicated in :Fig. .2, fluid will bedrawn into a -:fluid sreceiving chamber'bounded by the adjacent teeth of "the gears, and, as the =gears'mesh, the fluid will be dis- "placed "from the-chamber and delivered through the out let opening. By means of the passage 51 the fluid pressure at outlet 49 will also exist within the

chambers

29 and 41. Should this outlet pressure increase because of, for example, decreased demand, the pressure withinthe

chambers

29 and 41 will be correspondingly increased; The increased pressure within these chambers will dis;- place the piston 28 rightwardly and the piston 39 leftwardly, as viewed in Fig. 3. This movement of the pistons from their position of Fig. 2 to their position of Fig. 3, will be opposed by the force exerted by

springs

33 and 44. V

As will be apparent from Fig. 3, this displacement of the pistons corrwpondingly displaces the

gear

17 and 24 relative to each other and decreases the zone of the mesh of their teeth. As the gears are displaced by their abutting pistons, it will be apparent that the adjacent fingers on the

members

42 and 31, rotating with the gears,

will be inserted into the spaces between the gear teeth.

This shortening of the zone of mesh of the gear teeth and the corresponding plugging or occupation of the space between the unmeshedteeth of each of the gears thus serves to reduce the volumetric output of the pump and thereby returns the pressure of the fluid delivered by the pump back to a value approaching its original magnitude.

Upon a decrease in outlet pressure caused by, for example, an increase in demand, the pressure within the

chambers

29 and 41 will correspondingly decrease.

Springs

33 and 44 will thereupon move outwardly

members

31 and 42, together with

pistons

28 and 39, thereby increasing the zone of mesh of the gear teeth. The volumetric delivery of the pump will thereupon be increased to bring the fluid pressure delivered by the pump back to a value approaching its original magnitude.

It will be understood that these compensating move ments of the gears take place relatively rapidly so that their regulating elfect on the pump outlet pressure occurs almost instantaneously. It should be further evident that t openings in the housing adjacent the zone of mesh of said gears, and means responsiveto pump outlet pressure for simultaneously varying the -magnitude of the zone of mesh of said gears and for plugging the area between the unmeshed teeth of said gears, said means comprising dual pistons movable in opposite directions upon a variation in pump pressure, members axially aligned with each of said gears and movable with said pistons, multiple extending fingers on each of said members positioned within the area between the unmeshed teeth of said gears upon movement of said pistons,'an'd resilient means disposed centrally of and extending axially with the fingers of each of said members for urging said fingers out of the area between the unmeshed teeth of said gears, whereby the pump outlet pressure is balanced against the force exerted by said resilient means to modulate the volumetric delivery of the pump. 7 v

2. Aconstant pressure variable flow pump of the gear type comprising an elongated housing and a rotatable drive shaft extending therefrom, a drive gear'splined to the drive shaft within said housing, a meshing idler gear rotatably'mounted within said housing and adapted to be displaced longitudinally therein, opposed inlet and outlet openings in the housing adjacent the zone of mesh of said gears, and means responsive to a control pressure .for simultaneously varying the magnitude of the zone of .mesh of saidgears and for plugging the area between the unmeshed teeth of said gears, said means comprising dual pistons each contiguous with one. of said gears and movable in opposite directions in response to changes in said control pressure, members axially aligned with each of said gears and movable with said pistons, multiple extending fingers on each of said members positioned within the relative position of the gears shown in Fig. 2 repbecause of an increase in demand, but because of the variation in speed of the drive shaft. Thus, the pump can provide a constant outlet pressure although the speed of rotation of the drive shaft should vary.

Although the preferred embodiment herein disclosed illustrates the pressures in

chambers

29 and 41 to be a function of the pump outlet pressure, it will be apparent that passage 51 could be omitted and the pressure within the chambers could be made a function of an external would also occur if the variation in pressure occurred, not

controlling pressure which is independent of the fluid' being pumped. Control of the volumetric delivery of the pump can thus be accomplished independently of the pressure of the fluid being pumped.

While the invention has been disclosed and described in some detail in the drawings and foregoing description, they are to be considered as illustrative and not restrictive in character, as other modifications may readily suggest themselves to persons skilled in this art and within the broad scope of the invention, reference being had to appended claims.

The invention claimed is:

-1. A constant pressure variable flow pump of the gear type comprising an elongated housing and a drive the v shaft extending therefrom, a drive gear splined to-the. Y

the area between the unmeshed teeth of said gears upon .movement of said pistons, and resilient means disposed centrally of and extending axiallywith the fingers of each of said members for urging said fingers out of the area between the unmeshed teeth of .said gears, whereby said control pressure is balanced against the force exerted by saidresilient means to modulate the volumetric delivery of the pump.

3. A constant pressure variable flow pump of the gear type comprising an elongated housing and a driveshafit extending therefrom, a drive gear splined to the drive shaft within said housing, a meshing idler gearrotatably mounted within said housing and adapted to be displaced longitudinally therein, opposed inlet and outlet ,openingsinthe housing adjacent the zone of mesl 1 of,. said gears, means responsive to pump outletpressure for simultaneously varying the magnitude of the zone of mesh of said gears and for plugging the area; be-

tween theunrneshed teeth of said gears, said means comprising dual pistons movable in opposite directions upon a variation in pump outlet pressure, members axially aligned with each of said gears and movable with said pistons, multiple extending fingers on each of said members positioned within the area betweenthe urimeshed teeth of said gears upon movement of said pistons, and resilient means disposed centrally of and extending axially with the fingers of each of said members for biasing said gears into a relative position wherein theirv zone of mesh is a maximum, whereby the pump outlet pressure is balanced against the force exerted by said resilient means to modulate the volumetric delivery of the pump.

4. A constant pressure variable flow pump comprising a housing and a drive shaft extending therefrom, a drive gear splined to the drive shaft within said housing, a meshing idler gear relatively mounted within said housing upon an axis parallel to said drive shaft arid adapted to be displaced along said axis, opposed inlet and outlet openings in the housing adjacent the zone of mesh of said gears, means responsive to pump outlet pressure for simultaneously varying the magnitude of the zone of mesh of said gears and for plugging the area between the unmeshed teeth of said gears, said means comprising lit) dual pistons movable in opposite directions upon a variation in pump outlet pressure, a member movable with each of said pistons having multiple extending fingers, the fingers on each of said members being positioned within the area between the unmeshed teeth of said gears upon movement of said pistons, and resilient means disposed centrally of and extending axially with the fingers of each of said members for urging said fingers out of the area between the unmeshed teeth of said gears, whereby the pump outlet pressure is balanced against the force exerted by said resilient means to modulate the volumetric delivery of the pump.

5. A constant pressure variable flow pump comprising a housing and a drive shaft extending therefrom, a drive gear splined to the drive shaft within said housing, a meshing idler gear rotatably mounted within said housing upon an axis parallel to said drive shaft and adapted to be displaced longitudinally along said axis, opposed inlet and outlet openings in the housing adjacent the zone of mesh of said gears, and means responsive to pump outlet pressure for simultaneously varying the magnitude of the zone of mesh of said gears and for plugging the area between the unmeshed teeth of said gears, said means ineluding a piston movable upon a variation in pump outlet pressure for displacing one of said gears, a member movable with said piston having multiple extending fingers, the fingers on said member being positioned within the area between the unmeshed teeth of the other of said gears upon movement of said piston, and resilient means disposed centrally of and extending axially with the fingers of each of said members for urging said fingers out of the area between the unmeshed teeth of said gears, whereby the pump outlet pressure is balanced against the force exerted by said resilient means to modulate the volumetric delivery of the pump.

References Cited in the file of this patent UNITED STATES PATENTS 1,742,215 Pigott Jan. 7, 1930 2,052,419 Moore et a1. Aug. 25, 1936 2,079,375 McCollum May 4, 1937 2,149,326 Wilkin Mar. 7, 1939 2,463,950 Carroll Mar. 8, 1949 2,600,477 Burt June 17, 1952 2,666,293 Vigneau Jan. 19, 1954