US2887058A - Lubricated pump construction - Google Patents

Description

May 19, 1959 Filed May 29, 1953 ZZZ | L. ASPELIN TAL LUBRICATED PUMP CONSTRUCTION .ITZFE nfmrg 1 Les/1c L. A-Spe/uz John F Murray an? Dona/a L. Lorenz bLj y 1959 1.. L. ASPELIN ET AL 2,887,058

7 LUBRICATED PUMP CONSTRUCTION Filed May 29, 1953 6 Sheets-Sheet 2 Les/1e L. Aspe/Lzz I Ja/m F Marta $017410 Luz-e 22 L. L. ASPELIN ETAL 2,887,058

LUBRICATED PUMP CONSTRUCTION May 19, 1959 Filed May 29. 1953 6 Sheets-Sheet 3 Q If: PE 7:: ZQ T5 Leslie L. Afipe/in c/olzzz F Murray Dandy L. 1 01 y 1959 L. L. ASPELIN ET AL 2,887,058

LUBRICATED PUMP CONSTRUCTION Filed May 29. 1953 6 Sheets-Sheet 4 Leslie L. Aspe/jn v Ubfuz F Mzzrra z WMWM'MQM Dona/0 L. Lorenz bL HZZ May 19, 1959 s ET AL LUBRICATED PUMP CONSTRUCTION 6 Sheets-Sheet 5 Filed May 29, 1953 If: 1 E 7.7.5: T5

Les/1a L. Algae/112 8/6122; 2'' Mzzrra 9 orezzz Zuni/d L. L M

y 1959 L. ASPELIN ET AL 2,887,058

LUBRICATED PUMP CONSTRUCTION Filed ma 29. 1953 6 Sheets-Sheet 6 .Iz-zz Les/1e United States Patent LUBRICATED PUMP CONSTRUCTION Leslie L. Aspelin, Cleveland Heights, John F. Murray,

Macedonia, and Donald L. Lorenz, Euclid, Ohio, assignors to Thompson Ramo Wooldridge Inc., a corporation of Ohio Application May 29, 1953, Serial No. 358,452

12 Claims. (Cl. 103-4) This invention relates to the use of working fluid as a coolant and a lubricant for the journal and bearing surfaces of an engine driven fuel pump having rotary displacement means and, more specifically, involves the provision of a pump having pressure sensitive control means for by-passing quantities of working fluid pressurized by the pump to the journal and bearing surfaces at predetermined generated pressures elevated to a value corresponding to prescribed operating conditions of the pump, for example, when the engine is driving the pump or when the pump is being operated in excess of a predetermined per centum of rated speed.

In contemporary aircraft, there is commonly provided an engine which may be selectively actuated by a cranking motor for starting purposes and having an engine driven fuel pump for delivering a supply of pressurized fluid fuel to the engine.

It has been customary in aircraft fuel systems to determine the size requirement of a fuel pump by specifying a minimum flow requirement for the high pressure end of a maximum speed curve and by specifying a maximum flow requirement for the low pressure end of the maximum speed curve. Reference to such values provides the design limits of the pump and establish the volumetric efficiencies which are necessarily required for a properly designed fuel system.

In view of such specifications, it is mandatory that pump volumetric efficiency be kept as high as possible and internal pump leakage be kept as low as possible at the extremely low pump speeds which are encountered during the slow speed operation of the pump occurring during a typical starting operation when the engine is being actuated by a cranking motor.

Perhaps the most critical operating phase occurs during cranking or starting of the engine since fuel pump speeds are slow and pumpvolumetric efficiency is also low in comparison to the volumetric efficiencies obtained when the fuel pump is operated at rated speed.

Nevertheless, fuel system limitations do not tolerate the incorporation of an over-sized capacity pump to provide additional flow at low pump speeds. If such provision were made, extreme difliculties would be encountered in the design of fuel system controls to handle the excessive flows provided at maximum pump speeds.

\ In addition to the problems of capacity, those versed in the art will further appreciate that at low pump speeds when developed fluid pressures are also low, the bearing load on the fuel pump will be minimized and, accordingly, the problem of cooling and lubricating of the bearing surfaces for the rotary fluid displacement means in the fuel pump will be at a minimum during a typical starting operation. At rated speeds, however, the problem of providing adequate lubrication or cooling of the bearing surfaces and journal surfaces becomes critical.

In accordance with the general principles of the present invention, both of the problems discussed above are concurrently solved in a manner which affords greatly improved operating advantages. In its broadest aspect, the,

present invention contemplates the deliberate reduction of volumetric efliciency at high speeds and high pressures while maintaining the highest possible volumetric efliciencies at low speeds and low pressures through the provision of a lubricating system which includes pressure sensitive control means by-passing quantities of working fluid pressurized by the pump to the journal and bearing surfaces for use as a coolant and lubricant at generated pressure values which correspond to predetermined operating conditions.

In a preferred embodiment of the present invention, a pump casing having an inlet and an outlet with a pumping cavity therebetween houses rotary fluid displacement means to pump fluid from the inlet to the outlet. Journal and bearing surfaces are provided between the rotary fluid 1 pound centrifugal positive displacement pump is provided wherein a centrifugal pumping element is added in series with the rotary intermeshing gears of a positive displacement pumping stage. The volute pumping chamber of the centrifugal pumping element and the pumping cavity for the rotary gears are interconnected, the volute pumping chamber being provided with a pump inlet and the pumping cavity being provided with a pump outlet. Because the delivery pressure of the centrifugal pumping element varies as the square of the speed, there is provided a proper balance to the inlet losses of the gears which also vary as a function of the square of the speed.

It is an object of the present invention, therefore, to

provide an improved lubricating arrangement for a pump.

Another object of the present invention is to provide a fuel pump for a fuel system wherein bearing and journal surfaces in the pump are cooled and lubricated selectively at pressure values corresponding to optimum operating conditions. I i Y Yet another object of the present invention is to provide a pumping structure which will maintain highest possible volumetric efiiciency at low speeds and low pressures.

A further object of the present invention is to provide a lubricating arrangement for a high pressure pump which will operate to reduce volumetric efliciencies at high speeds and high pressures without afiecting materially volumetric efficiencies at low speeds and low pressures.

Another object of the present invention is to provide a pump structure which uses working fluid as a coolant and lubricant for the journal and bearing surfaces of the rotary fluid displacement means only when the working fluid is pressurized by the pump to pressure values corre- Figure l is an elevational view of a pumpincorporafl ing the principles of the present invention.

Figure 2 is an enlarged view of the pump showniu,

Patented May 19,1959

asst-,oss

. Figure l but showing a cross section to illustrate additional details of construction of the pump.

Figure 3 is a cross sectional view taken substantially on line *IIIIII of: Figure 1.

Figure-4=is a partial crosssectional view taken sub: stantially: on. line. IV-IV of. Figurev 3. and. illustrating additional. details of. construction of. the gear members providedin. accordance with the principles .of the present invention.

Figure 5 is a cross sectional-view taken, substantially on line VV of. Figure 3 but with parts. removed for the sake of clarity and. with parts shown-in elevation.

Figure 6 is a graph showing performancecurvesofa pump-v provided in, accordancewith the. principles of the pnesentlinvention.

Fignre-lis a. fragmentary cross sectional. view with. parts; removed and: with, parts shown in elevation, taken substantially on line-VII--VI-L-of Figured.

Figure; 8.- is afragmentany; cross. sectional view with parts removed: and with partsashown. in; elevation taken substantially on. linev VII-I-VII-L of Figurel.

Figure 9 is a fragmentary cross sectional view. taken substantially. along the line IX-l-X of Figure 8.

Figure 10 is a partialcross sectional View showing in elevation the face structure of the, movable bushing membersand taken substantially on line.XX of. Figure 3.

Figure 11 is a cross sectional view with parts. shown in. elevation of an alternative embodiment according to the principles. of the present invention.

Figure. 12 is a partial cross. sectional view showing in elevation the. movable bushings provided in. accordance with the principles of the present invention and taken substantially on line XII.-XII of Figure 1 1.

Figure 13 is a cross sectional view with parts shown in elevation and with. parts removed taken substantially on line XlH--XIII of Figure 1-1.

Figure 14 is. a fragmentary enlarged cross sectional view taken in the plane of Figure 11 and showing additional details; of construction of one of the control valve members provided in accordance with the principles of the present invention.

Figure 15 is a cross sectional fragmentary view taken substantially-online XV--XY of Figure 13.

, Figure 16'is a plumbing diagram, showing the fluid flow pathsinaccordance-with the principles ofthe present invention.-

As shown on the drawings:

In-the formjofthe;inventionillustratedin Figures 1,-1'0, a: pump is; generally indicated by the. referencenumeral Ztkandcomprisea a casing. or. a housingZl, providing: an. inlet 22 communicating with a pair of adjacently spaced.

pumping cavities, 23. and. 24, each respective pumping cavity; communicating with the inlet; 22 bygan inlet passagerindicatedtat26 andarr, inlet passage indicated at 27, respectively. The casing or housing'll provides-a discharge passage 28 for the pumping cavity 23 and adischarge passage 30 for the pumping cavity 24. The casing or housing 21 further provides a filter housing. 29 which communicates with: the discharge passage 28 and a filter, housing 31 whichcommunicates with the discharge passage30. The. pumping cavities. 23 and 24 receive identical pump. components; and, accordingly, like reference numerals, will be applied to the common.components;whereverpossible.

Referring specifically toFi'gure-fi it will be-noted that thecasing o1'.- -housing- 21 is closed at one-end by a cover. member. 32.which.passes.a.stub. shaft 33 splined as at 34. so, a's to effect a. mechanical coupling, with an engine Eiadapted to receive pressured fluid fuel at pressures generated by the pump 20; A cranking motor M1 is coupled as at 37 to the engine E in order to selectively actuate the engine E for starting purposes; It will be understo'odtliatthe cranking' motor M turns over the engine E at comparatively slowspeeds, thus, concurrently actuating. the. accessories associated with the engine B such as the fuel pump 20 through the mechanical coupling 36. However, once the engine E is started and operates in a self-sustaining manner, the pump 20 will be operated at rated speeds through the mechanical drive connection 36 effected between the engine E and the pump 20.

The stub shaft 33 is provided with an enlarged hollow hub portion fid internally splined asat 39=to effect. a driving coupling with a shaft extension 40 extending from one faceofadriver gear 41 rotatable in the pumping cavity 2 The driver gear 41. and the shaft extension 40 has an axially extending passageway 42 extending therethrough and receiving a rotatable shaft member 43 which is splined as zit-44 to efiect a mechanical coupling with a second driver-gear." 46 rotatable in the pumping cavity '23.

At the other end of the shaft 43 is provided an enlarged splined hub. 47. which efiectsa mechanical, couplingwith. the stub, shaft33. at the. interiorly splinedhub portion 38. thereof. a

A continuous biasing spring, 48 is bottomed between thestub shaft 33 and the shaft member 43, the sides of the splined hub portion 47 providing a stop engagement with the shaft extension 40, thereby permitting any loose: ness to be taken up by the spring 48.

The driver gear 4i meshes witha driven gear 49 and, the driver gear 46 meshes with a driven gear 50, thereby providing rotary fluid displacement means in the respective pumping cavities, 23 and 24 for moving and pumping fluid from. the inlet 22v to. the. respectiveoutlet passages 28 and 30.

In accordance with the principlesofthe present invention, separate bearing bushing. means are. provided in the casing or housing 21 between the rotary fluid displacement means,,including the. gear members 41, 46, 49, 50 and the. casing or housing 21 in order to establish bearing and journal surfaces.

First of all, each set of gears is provided with a corresponding set of stationary bushing members 51 which are generally tubular in configuration and are provided with radially extending flange portions 52.- forming a sealing face for engaging the adjacent side face of a corresponding gear member.

The flange portions 52 are generally circular, howevenaflat portion is provided at the peripheries thereof so that each adjacent set of bushing members 51 providea flatimating abutment joint 53 preventing rotation of. the bushing members 51.

Each of the stationary bushing members 51 is particularly characterized by the provisionof an annular lubricant 'rccessfid located directly adjacent the corresponding gear side faces at the. jo rnal surface ofthe shaft. extensions of-the.'gea1's. Extending, generally axially of the lubricant recesses 54 are lubricant grooves 56 provided to carry lubricant along; the bearing and journal surface.

If desired, the grooves 56 may be blind ended as at 57 since the-portions of the casing or housing 21 behind the stationary bushing members 51 may be referenced to lower pressures such as the pump inlet pressure in order to prevent the formation of high pressure pockets within the. pump.

On the opposite side of each of the gear members 41, 46, 49, 50, a movable pressure loaded bushing member 58 isprovided.

Each of the movable bushing; members 58 is of gen erally tubular.- configuration andincludes a radially extending flange portion 59 providingv a front sealing facc 6t) engaging the adjacent side facev of a corresponding gear member and a radially extending back face so. which is spaced from an adjacent wall '61 provided by the casing or housing 21 in order to form a pressure control chamber 62 receiving pressurized fluid generated by the pump in order to. subject the back. face 60, to fluid pressure for loading the. movable bushings 5.8 into sealing;

engagement with. the gears.

naaagoes In order to communicate fluid at pressures generated the pump to the back faces 60.

It will be noted that the flange portions 59 of the movable bushings 58 are generally annular in configuration, however, the peripheral portions thereof are flattened on one side so as to provide a mating abutment joint between adjacent sets of movable bushings 58 indicated at 64, thereby to keep the bushings 58 from rotating.

The bearing surface provided by each respective movable bushing 58 to journal a corresponding gear is particularly characterized by an annular lubricant recess indicated at 66. Extending generally axially of the bearing surface is a lubricant groove 67 to carry lubricant throughout the bearing and journal surface. If desired, the grooves 67 may be blind ended as at 68.

As shown in Figure 10, it will be noted that the sealing face 60 of the movable bushings 58 is also characterized by an arcuate groove 68 offset towards the discharge side spring retainer member 69 is provided to engage the end portion of each movable bushing member 58 and a coil spring 70 is provided for each pair of movable bushing members to continuously bias the movable bushing members towardsealing engagement with the respective gears.

The annular recesses 54 formed in the stationary bushing members 51 and the annular recesses 66 formed in the movable bushing members 58 are intercommunicated by axially extending passages 71 formed in the gear members 41, 46, 49, 50.

In starting the engine E, it is necessary to supply a sufficient quantity of fuel to provide power to run the engine E and this fuel must be supplied at a pressure sufiicient to overcome any high pressure drops which may be inherent in the fuel system of the engine.

In a typical aircraft fuel system for which the pump of Figures l-lO would be suitable, engine starting flow and pressure conditions must be met at pump speeds in a range between 200 and 300 r.p.m. At these rotative speeds, the volumetric efficiency of the pump is very low,

for example, in the order of 30 percent, whereas at rated speed, upwards of 3600 rpm, the volumetric efficiency will be in the order of 90 percent. Since the fuel system requirements may call for the delivery of a minimum quantity of fuel at low speed and a maximum flow of fuel at high speed, design improvisation in order to compensate for one condition will seriously affect the other condition. Moreover, at low operating pressures and slow speeds, the bearing and journal surfaces of the pump require no special lubrication, however, at high speed operation, normal fluid leakage across bearing and journal surfaces is insuflicient to properly protect the surfaces and it is necessary to artificially force a supply of the pressurized Working fluid across the bearing and journal surfaces to provide the necessary cooling and lubricating action.

In accordance with the principles of the present invention, the working fluid is used as a coolant and lubricant for the journal and bearing surfaces only when the engine E is driving the pump 20, or, in other words, only when the pump is generating pressures in excess of a predetermined per centum of pressure value at rated volumetric efficiency, which condition corresponds to a rotative speed of the pump in excess of a predetermined per centum of rated speed.

These ends are obtained by utilizing a poppet valve loaded against a seat subject to pressures generated by the pump and controlling passage means selectively communicating fluid to the recesses and grooves 54, 56, 66, 67.

In the pump 20, two separate rotary fluid displacement means are provided which work independently of one another. The shaft member 43 is provided with a reduced shear section 72 having less resistance to torsional shear than the other portions of the shaft member 43. Furthermore, the shaft extension 40 is also provided with a reduced shear section 73 which is located between the hub portion 38 of the stub shaft 33 and the end of the stationary bushings 51 associated with the driver gear 41 and the driven gear 49.

A reduced shear section 74 is provided in the hub portion 38 to establish a zone of lesser torsional shear re-' sistance adjacent the shaft extension 40 and radially outwardly of the end thereof. It will be manifest, therefore,

that the various shear sections are properly placed so that one element of the multi-element pump 20 may remain operative even though failure of the other element occurs through binding, seizure or other mechanical locking action which would cause shear failure of one of the shear sections 72, 73, 74.

For this reason, each pumping element of the multielement pump 20 is provided with separate valve control means for regulating the flow of coolant and lubricant to the respective journal bearing surfaces. In other words, control valve means are provided which are completely independent of each other and which are independently referenced to the fluid pressures generated by each respective pumping element.

Referring to Figures 7, 8 and 9, it will be noted that the pressure just upstream of the filter in each respective.

filter housing 29 and 31 will be approximately equal to the discharge pressure of a corresponding rotary fluid displacement means as delivered to a discharge passage 28 and 30, respectively. Each control valve assembly is in-- dicated generally by the reference character V and includes a poppet valve having a valve head 76 loaded by a coil spring 77 against a valve seat insert 78 subject to pressure upstream of the respective filters as is contained in the passages indicated at 79. t i

The spring load exerted by the coil springs 77 against the respective poppet valve head 7 6 and loading the poppetvalve heads into closed position is opposed by the discharge pressure of the respective pumping element working to force the poppet off the valve seat. Accordingly, when the discharge pressure of a corresponding pump is of such a value to overcome the spring load,

fluid pressure values generated by the pump will flow through the orifice 80 provided in the valve seat insert 7 8 across the valve seat and through the valve to a chamber 81 formed within the casing or housing 21.

Fluid flowing into the chamber 81 is communicated to a recess 82 provided by the casing or housing 21 immediately adjacent the respective stationary bushing members 51. i

In order to intercommunicate the recesses 82 and the recesses 54, each respective stationary bushing member 51 is provided with a passageway 83.

As shown in Figure 5, the hollow portions of the pump casing or housing 21 are referenced to inlet 22 by means of a passageway 84 controlled by a check valve 86, thereby precluding any pressure build up which might result in high pressure pockets being formed within the pump housing.

There is thus provided in the pump of the present invention a closed fluid circuit to eifect a series flow of fluid through the circuit from the pump outlet to the journal and bearing surfaces of the rotary fluid displacement means and back to the inlet. Moreover, pressure sensitive valve control means are provided in the closed faces only at predetermined pressures.

More specifically, fluidat pressures generated by the pumping element will flow from thepassage 79 through the orifice 80, over the-valve seat, into the chamber 81, through therecess 82, through the passage 83, into the recess 54, throughout the grooves 56, through the passages in the gears 71; into therecess 66, through the grooves 67, and from the grooves-56 and 67 past the blind ends 57 and-68, through the passage 84; past the check valve 86 and back to the inlet 22.

It will be appreciated that" during the period of operation when thecontrol valve assemblies V are open, the recess grooves 54 and 56 at" the ends-of: the journaland bearing surfaces adjacent the gear memberswill-befilled with pressurized working fluidthereby flooding the bearingand journal surfaces withan adequate supply of coolant and lubricant so as to properly-protect the bearinga-ndjournal surfaceswlien' subjected to high loads.

As shown in Figure 2, thepump' 20" isprovided with a:

safety relief; valve assembly indicated generally at 86 which'will operate not only'to limit thepressure at which fuel is supplied to an engine operating control but also to limit the quantity offlow supplied to the engine control. A by-pass passage 87 is formed between the discharge passageway 28 and the inlet 22 and receives a valve seat insert 88 controlled by a valve member 89 slida-bly carried in a sleeve 90, a coil spring 91 being located between the sleeve and the valve member 89 to normally seat thevalve on the seat 88.

A restricted passageway 92 is provided in' the valve member 89'and' admits-discharge pressure to a; first chamber 93 in the sleeve member 90.

A second valve member 94 biased by a spring 96 has a needle portion 97 controlling a medial aperture 98 formed between the chamber 93 and a second'charnber 98. Openings 99 are provided in the side walls of the sleeve-90communicating fluid in'the chamber 98 to the inlet 22.

By virtue of the arrangement provided, a large volumetric flow will be by-passed with a small pressure rise.

In the embodiment illustrated in Figures 11-1'5, the principles of the present invention are obtained through the utilization of small control valves incorporated directly-into the bearing and journal surface'defining means. As illustrated in these views, thepump is indicated generally-by the reference numeral 100 and includes a casing or housing 101 providing an interconne'ctedvolute pumping: chamber ll02'anda pair of axially spacedpumping.

cavities 103 and104;

The pumping casingor housing 101 is provided with an, inlet 106 which communicates with the volute pumping chamber 102 and with an outletcommunicating'with the pumping cavities 103 andllM, thereby to establish aseries- The rotary fluid, displacement means provided in the pumping cavities 103 and 104 take the formof-rotary intermeshing gears, includingdriver gears 110and 111 and driven gears 112 and 113.

The casingor housing 101 is closed bya cover. member 114 which passes the end of a shaftmember 116 splincd as at 117 to effect a mechanical coupling'with a drive connection 118 leading from an engine E selectively cranked through. a mechanical connection; 119,; with; a starting or crankingmotor M; The-usual seal and-bean ing means are provided between the cover member 114 andthe shaft member 116*.

Asplined connection 120 is effected between the driver gear 110 and the shaft membenllG, the shaft member 116 extending throughthe driver gear 110, through the driver gear: 111 and having keyed onthe free end thereof, a gear member 121.

T heshaft' member 1 16 is also provided with a splincd connection 122 to the driver gear 111.

At one end of the driven gear 113, a reduced tubular extension 123 is provided and carries a bushing member 124 for journaling a gear member 126 meshing with the gear member 121. The gear member 126 is firmly connected tothe hub portion 108 of the centrifugal impeller 107 by means of'fasteners indicated generally at 127. The usual seal and bearing means are provided between the impeller 107, the. gear member 126, and the casing or housing 101;

As ischaracteristic of rotaryv meshing gears in a positive displacement pump, the inlet losses to the gears will normally vary as the square of the rotational speed of the gears. By the addition of the centrifugal pumping element in series with the gear elements, the inlet losses to the gear pump are nullified since the pressures developed by the centrifugal pumping. element overcome the inlet losses. of the gear stages. In other words, be cause the delivery pressure of the centrifugal pumping element variesas the square of the speed and because the inlet losses to' the meshing. gears is also a function of the square of thespeed, a. proper balance is established. By virtue. of such provision, gear sizes may be minimized and bearing loads-are also effectively minimized. It is also possible withsuch an arrangement to obtain a high output with high pressure delivery even though a particularly compact pumping unit is provided.

In providing bearing and journal surfaces between the rotary fluid. displacement means 110, 111, 112, 113 and the casing or housing 101, the pump 100 differs from the pump 20 in that separate stationary bushings are not provided. Rather, the casing or housing 101is provided with the reduced diameter bores indicated at 128 for receiving, the respective gear shaft extensions of the gear members 110, 111, 112, 113.

As in the stationary bushings 51 ofthe pump 20, the bearing surfaces providedeby the bores 128 in the pump 100 areparticularlycharacterized by the provisionof annular, recesses 154 and: with generally axiallyextending lubricating grooves 156- Which extend along the bearing. and journal surface; and which may be blind. ended as, at157.

The movablebushings of the pump 100' are indicated by the reference numeral 129 and take the form of stepped cylindrical members having a flange portion 130 providing a sealing face 131 onone side anda pressurereceiving back face 132 on the other side thereof. The sealing-face 131 sealingly engages the adjacent side faces of the corresponding gear members 110, 111,112 and 113 and the pressure receiving back face 132 is spaced from an adjacent radially extending wall 133 provided by the casing or housing 101 so as to form a pressure control chamber 134, whereby fluid pressure may be applied across the back face 132 for pressureloading the movable bushings 129 into sealing engagement with the corresponding gearmembers.

As shown in Figure 12, fluid at pressure generated by the pump maybe communicated to the respective pressure control chambers 134 by means of passagesllfie ex tending through the flange portions 130 at the discharge side of the pump.

The movable bushings 129 are further provided. with the; medial annular shoulder 137 particularly characterlzed by anannulargroove 138 receiving an O-ring seal member" 139 for-establishing-a seal between themovable bushing members 129 and the casing1or housing. 101 behind thepressurecontrol chambers-134. TheamediaLahassaoee nular shoulders 137 are received in corresponding counterbores provided inthe casing or housing 101, sufficient clearance being provided to accommodate adjustable movement of the movable bushings with respect to the casing or housing 101.

Each of the movable bushings 129 terminates in a reduced tubular extension indicated at 140 and providing an end face for bottoming a coil spring 141, each coil spring being arranged to provide a continuous biasing force against opposed sets of movable bushings in the multiple arrangement provided in the pump 100.

Similar to the movable bushing members 58 of the pump 20, the movable bushing members 129 of the pump 100 are provided with annular lubricant recesses 142 as well as with generally axially extending lubricant grooves 143 for carrying a supply of lubricant along the bearing and journal surface, the grooves 143 being blind ended, if desired, as at 144.

In order to communicate fluid pressurized by the pump to the journal and bearing surfaces, each of the movable bushing members 129 is provided with a generally axially extending inclined passageway 146 which communicates the respective recesses 142 with a corresponding pressure control chamber 134. In other words, the passage 146 is provided in each respective movable bushing member 129 in such a manner as to intersect the pressure receiving back face 133 and the bearing surface provided to journal a corresponding rotary fluid displacement member. Since the back face 132 is subject to fluid at pressures generated by the pump, there is established a closed liquid circuit which includes in series the pump outlet, the journal and bearing surfaces, and the pump inlet. It will be understood that the portions of the casing or housing 101 spaced away from the pumping cavities 103 and 104 are referenced to inlet pressure in the usual manner, a typical arrangement having been described in connection with the pump 20.

The control valve means of the inventive embodiment of the pump 100 is illustrated 'in appropriate detail in Figure 14. As shown in Figure 14, thepassageway 146 may be conveniently formed by drilling or by suitably shaping the passageway 146 in generally cylindrical form. There is received within the passageway 146 an insert sleeve member 148 shaped to be complementary in com figuration to the passage 146. The sleeve member 148 is preferably tubular so as to provide an open ended bore 149. partially=closed as at 150 so as to form a restricted orifice 151. The. partial closure 150 provides a valve.

seat around the orifice 151 cooperating with a ball valve member 152. The opposite end of the insert sleeve memher 148 is peened over as at 153 to engagingly abut one end of a coil spring 154, the opposite end of which engages the valvemember 152 so as to normally close the passage 146. a

On the opposite sides of the gears, the casing or housing 101 is provided with passageway means so that control valve means may be referenced directly to pump discharge pressure.

As shown in the drawings, the bearing surfaces of the casing or housing 101 are provided with a passage 160 which opens into a trapping relief recess 161 and which is intersected by an angularly inclined recess 162 arranged to intersect the bearing surface directly adjacent the corresponding gear members, for example, at the lubricant recesses 154.

In each of the passages 162, there is provided an insert sleeve meber 148 constructed identically with the sleeve member described in connection with Figure 14.

In the operationof a gear pump, measurement of pressures around the periphery of the pumping gears will indicate that the pressures vary both as to the speed of rotation of the pump and discharge pressures from a maximum adjacent the discharge side of the pumpto a minimum adjacent the inlet side of the pump. Accordingly, the total forces tending to separate the floating or.

ll) movable bearing members from the mating gear side faces and the line of action of that force will tend to change as the speed of rotation of the gear members changes.

To provide a pressure loading force on the movable bearing members 129 which would be equal and opposite to the separating forces developed in the pumping cavities 103, 104, it would be necessary to actually change the.

quantitative value of pressure force as well as the line of action of application.

In order to correct any instability which may occur as a result of such phenomena, it is necessary to minimize the effect of rotative speed upon the separating forces. To accomplish this end, discharge pressure may be deliberately bled across the face of the movable bearing members 129 toward the inlet or low pressure side of the pump. This function is accomplished by a face groove such as the groove 68 shown in Figure 10.

In the bearing surface means provided by the casing orhousing 101, a similar groove is shown at 165, which groove is provided in a location radially outwardly of the root diameter of the adjacentgear teeth.

Additionally, there is provided a secondary groove 163 which is located below the root diameter of the adjacent gear teeth and which groove is referenced to a source of high pressure. The secondary groove 163 provides a static pool of high unitpressure working against the gear face, thereby increasing the separating forces acting between the fixed bearing face and the adjacent gear and operating to bring into balance the separating forces acting between the movable bearing members 129 and the mating gear face engaged by the sealing face 131 o the movable bearing members 129.

By way of summary, reference may be made to the performance curves shown on Figure 6 which illustrate the advantageous operating characteristics of the improvements effected by the present invention.

The preferred embodiments herein described and illustrated are usually associated with an engine E which will be cranked under starting conditions by a cranking motor M at cranking conditions which rotate the rotary fluid displacement means of the pumps 20 and in the order of 200 to 300 r.p.m. with developed pressures ranging in the order from to 200 pounds per square inch gauge. Gear pump efficiency under such conditions is usually such as to afford a volumetric efficiency in the order of 30 to 40 percent.

By utilizing a valve controlled lubricating system in accordance 'with the principles of the present invention, the pump volumetric efiiciency is relatively lowered at higher speeds and pressures so that the pump may be designed for higher displacement which becomes effective at the low speeds and low pressure where flow is not being by-passed through the valve control lubricating, system.

As is illustrated by the dashed line NO, the eifect on pump capacity of a relief valve set to crack open at a pressure of 350 pounds per square inch gauge is indicated. The area prescribed by the area shown on the graph OPQ represents the flow through the valve controlled lubricating system, a flow which would be refiected in pump performance as a loss similar to ordinary internal leakage losses.

Although various minor structural modifications might be suggested by those versed in the art in connection with the structural embodiments herein disclosed in considerable detail for the purpose of clarity, it should be understood that. we wish to embody within the scope of the patent warranted hereon all such modifications as reasonably and properly come within the scope of our contribution to the art. j

We'claim as our invention:

1. In a pump, a casing having an inlet and an outlet, rotary fluid displacement means in said casing to pump fluid from the'inlet to the outlet, journal and bearing surfaces between the rotary. fluiddisplacement means and said casing, meansaformingaflow path providing a.closed fluid circuitincluding, irr'series,. said. outlet, one of said journal and bearingsunfaces, and: said inlet, and a..pressuresensitive valve controlimeansdn said flow path. betweensaid outlet. and said journal. and bearing surfaces opening in responseto pump-generatedv pressure for controlling the flow. of fluid to said. surfacesonly at predetermined pressures at; said. outlet.

2. In a pump, a casing having an inlet and an outlet, rotary fluid displacement meansv in. said casing. moving fluid from said. inlet to said outlet, journal and bearing surfaces between said rotary fluid displacement means and said casing, passage defining. means communicating fluid pressurized by said. pump tosaid journal; and .bearing. surfaces, and z a control valve in. said passage defining meansrresponsive to pump-generated pressure to selec tively regulate. the communication offiuid at increased pressureto said journal andbearing'surfaces- 3. Ina. pump, a. casing having. an inlet. and an outlet,

rotary fluid displacement means in said casing moving fluid from said inletto: said outlet, journal and bearing surfaces between said rotary fluid displacement means and: said casing, passage defining means communicating fluid pressurized by said pump to said journal and hearing surfaces, and a pressure sensitive valve in said passage defining means responsive to pump-generated pressure communicatingpressure to said journal and bearing surfaces only at predetermined pressure values.

4. In a pump, a casinghaving an inlet and an: outlet, rotary fluid displacement means in said casing moving fluid from said inlet to said outlet, journal and bearing surfaces between said rotary fluid displacement means and said casing, passage defining means. communicating fluid pressurized by said pump to said journal and bearing surfaces, and control means includinga' valve insaid: passage-defining means and automatically openingandclosing said passage defining means. as a function of the rotational speed of the pump.

5. In a pump, a housing. having. an inlet and arr-outlet and providing. a pumping cavity, rotary' fluid displacement means in said cavity, and abushing means in said housing providing a backingsurface for said cavity and a journal and bearing surface for said rotary fluid displacement means, said bushing means having; a pressure; receiving back surface forming together with saidhousing a. pressure control chamber, means placing said pressure control chamber inpressure communication with.said.outlet, and means forming a passageplacing said journaland bearing surface in communication withlsaidpressure control chamber, saidlast men'tioned means'including a .control valve insaidpassage operable to control the flow of fluid from said pressure controlchamber to said. journal and bearing: surface as a function of pumpspeed.

6. In a pump, a housing having an inlet and an outlet and providingapumping cavity, rotary fluid displacement means insaid cavity, and a bushing meansrin said housing providingta backing surface for said cavity and a journal and bearing-surface" for said rotary fluid. displacement means, said bushing: means having.v a pressure receiving back surface forming. together with said. housing a pressure control. chamber, meansplacing said'pres sure control chamber in pressure communication with said outlet, andmeans forming a: passage" placingsaid journal. and bearing surface inn-communication with said pressure controlchamber, saidllastmentioned means including a pressure sensitive control valvein said passage to regulate therflow of fluid from. said pressure control chamber-to said journal and bearing surface as a function of 1 the 1 pressure in saidpressure control chamber.

7. A multiple pump comprising a single: housing: providing multiple pumping cavities each having an inlet and an outlet, rotaryxfluid displacement means in each cavity to pump fluid from a? corresponding inlet. to a corresponding. outlet,. means. in. said" housing providing bearing: and journalw. surfaces .for' each. respective rotary 12 fluid displacement; means, afilten housing: communicating with, each respective:outletrandleachhaving itsown discharge: op'ening,.a relief valve assembly for: eachpumping. unit including a poppet loadedwagainst a seat exposedtopressure generated by the pump; atthe: respective pump.- outlets, means providing passages independent of one another and each independently referencing a corresponding, relief valve assembly to pressures generated by the pump upstream of a corresponding filter housing. but downstream of a corresponding. outlet, and means providing passages independent of one another and'each independently communicating fluid flowed past .a corresponding poppet to. a corresponding one of said bearingand journal surfaces, whereby; said pumpv will discharge.

' through the; respective filter housingshut quantities of working fluid at a predeterminedpressure: value will be selectively, bledto therespective journal andrbcaring surfaces.

8.. A multiple: pump comprising asingle housing providiug multiple: pumping; cavities having. an inlet: and:' an outlet, rotary fluid, displacement means in each cavity to. pump-fluid from the inlet to theoutlet, means in said housing; providing. bearing; and journal-surfaces for. each respective rotary fluid displacement means,..a filterhouse ingcommunicating with'theoutlet and having a discharge openinga-relief valve assembly including apoppeteloaded against aseat exposed to pressuregenerated by the' pump, means providing; passages referencing the relief valve assembly to. pressure'generated by; the pump upstreamrof the filter housingbut downstream-of the outlet, and means providing passages communicating fluid flowed past the poppet to: said bearing and journal surfaces, whereby saidpump; will discharge: throughthe filter housing but quantities of working fluid at a predetermined. pressure value-will be selectively bled to the journal and bearing surfaces.

9. A multiple pump comprising a housing providing multiple pumping. cavities and having an inlet and. an outlet, rotary fluid displacement means in each cavity for pumping fluid from the inlet to the outlet, bearing ands. journal surface forming means in said housing for the respective rotary: fluid displacement means,: said bearing and journal surface'formingmeanshaving pas.- sages formed therein-communicating Working fluid pres; surized, by'therpump to the. housing and journal surfaces formed thereby, and. a separate valve. in. each respective passageincluding a poppet loaded: against a seat subject to saidpressurized; working. fluid to cool and lubricate'saidsurfaces selectively.-

10. A pump comprising a housing having. a pumping cavitywith an inlet and an outlet, rotary intermeshing gears in said cavity pumping fluid from said inletto said outlet, stationary bearing bushing means in said housing on one side of said gears providing a bearing surface for journalingsaid gears: and having. an annular lubricant recess adjacent the gears and at least. one: gen-.- erally axially extending: lubricant groove communicat ing therewith in the bearing surface, movable pressure loaded bushing means in said housing on theother side of said gears providing a bearing surface. for journaling. said gears, a sealing surface for engaging the side faces: of; the: gears; and: further providing; an annular lubricating, recess. adjacent the gears; with. at least one generally extendinglubricant groove come municating therewith in the bearing, surface, recessmeans extending through saidgears interconnecting said annular recesses, passage-defining means'supplying working fluid at pressures generated by the pump to said recesses and grooves for cooling and lubricating; the bearing surfaces and a valve in said passage-defining means controlling the supply of working fluid only at predetermined pump-generated, pressures.

11. A pump comprising a housing having-a pumping cavity with. an: inlet and an. outlet, rotary intcrmeshing gears: in. said: cavity pumping. fluid from. theinlettto the 13 outlet, stationary bearing bushing means in said housing on one side of said gears providing a bearing surface for journaling said gears and having an annular lubricant recess adjacent the gears and at least one generally axially extending lubricant groove communicating therewith in the bearing surface, movable pressure loaded bushing means in said housing on the other side of said gears providing a bearing surface for journaling said gears, a sealing surface for engaging the side faces of the gears, and further providing an annular lubricant recesss adjacent the gears with at least one generally axially extending lubricant groove communicating therewith in the bearing surface, recess means extending through said gears interconnecting said annular recesses, a valve assembly having a poppet loaded against a seat subject to the said pressures generated by the .pump, and passage means controlled by said valve assembly selectively communicating fluid to said recesses and grooves for cooling and lubricating only when said pump generates predetermined pressures.

12. A pump comprising a housing having a pumping cavity with an inlet and an outlet, rotary intermeshing gears in said cavity for pumping fluid from said inlet to said outlet, movable bearing bushing means providing a sealing face engaging the side faces of the gears, a bearing surface for journaling the gears, and a pressure loading face subject to fluid pressures generated by the pump, said bearing bushing means having a I recess extending therethrough intersecting said bearing References Cited in the file of this patent UNITED STATES PATENTS 1,379,587 Fisher May 24, 1921 1,617,986 Blank Feb. 15, 1927 2,055,587 Pigott Sept. 29, 1936 2,281,302 Amery Apr. 28, 1942 2,286,301 Parsons June'16, 1942 2,420,622 Roth et al. May 13, 1947 2,437,791 Roth Mar. 16, 1948 2,505,191 Lauck Apr. 25, 1950 2,639,694 Johnson May 26, 1953 2,676,548 Lauck Apr. 27, 1954 2,724,335 Eames Nov. 22, 1955 2,726,604 Aspelin Dec. 13, 195

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