US2977886A

US2977886A - Fuel pump

Info

Publication number: US2977886A
Application number: US501019A
Authority: US
Inventors: Oscar H Banker
Original assignee: Fawick Corp
Current assignee: Fawick Corp
Priority date: 1955-04-13
Filing date: 1955-04-13
Publication date: 1961-04-04
Anticipated expiration: 1978-04-04

Description

April 4, 1961 BANKER 2,977,886

FUEL PUMP Filed April 13, 1955 3 Sheets-Sheet 1 FIG 1 H G1 2 mmvroa. Oscar J2. Ban/(er April 4, 1961 O BANKER 2,977,886

FUEL. PUMP Filed April 13, 1955 a Sheets-Sheet 2 1N VEN TOR. 7 Oscar J1. flan/(er :4 array 0. H. BANKER FUEL PUMP April 4, 1961 3 Sheets-Sheet 3 Filed April 15, 1955 IN VEN TOR. OscarJz. flan/(er FIG. 1%

FUELPu r "and Apr. 13, 19 s, Ser. N6. 501,019 7 Claims. 01.103-11 This invention relates to fuel pumps for internal com bustion engines used to power automotivevehicles.

It is a well known fact that when the. fuel pumps of present day gasoline-burning internal combustion engines in automotive vehicles become heated above a predetermined temperature,dependingupon the characteristics of the particular gasoline used, the gasoline will form a vapor which, because of its compressibility, interferes with the further functioning of the pump to transfer gasoline from the fuel tank to the carburetor of the engine. This condition is generally referred to as a vapor lock. Without fuel, the engine ceases to operate and cannot be made to resume its operation until the temperature of the fuel is reduced sufliciently to eliminate its spontaneous vaporization. Since effective cooling media .are notv usually readily available on the spot, the vehicle is immobilized until air currents perform the necessary cooling operation. On a hot day, this is a slow process.

It is. an object of this invention to provide a-fuel pump for an internal combustion engine of such design that its operation will not be materially affected by the presence of vapor. i

Internal combustion engines used in automotive vehicles may be divided roughly into those operating on the fuel injection principle, such as the diesel engine, and those operating on the pre-mixed fuel-and-air principle such as the ordinary gasoline engine equipped with a carburetor. The fuel injection type operates at higher pressures than the carburetortype, the former utilizing a light oil at approximately 75 pounds per square inch pressure, where as the latter should not feed the fuel to the carburetor at pressures exceeding 5 pounds per square inch. Both forms, however, are subject to vapor lock, the diesel type being particularly susceptible after a long uphill climb,

followed by a downhill coast against the engine during which the fuel is converted into a frothy mixture containing a large amount of air which renders the mixture compressible and hence incapable of being operated upon by the pump to cause a flow of the liquid fuel to the injection nozzles of the engine.

It is another object of this invention, accordingly, to.

provide a fuel pump for automotive vehicle internal combustion engineswhich may be utilized either with high pressure fuel injection systems, or with relatively low pressure carburetor fuel feeding systems, and which nevertheless will be equally effective to pass any vapor, entrained air, or frothy mixture through the fuel feeding system. i r

A more specific object of this invention is the provision of a pump for a fuel feeding system for an internal combustion engine wherein the pump is provided with means for minimizing the feed-back of vaporized fuel from the pressure side 'of the pump to the intake side thereof and thereby tominimize the conditions under which a vapor lock forms. i

. A specific object-ofthisvinvention-is the provision of a side-sealing means fora gear type pump which shields Patented Apr. 4, 1961 thereon by the side sealing'means, thereby reducing friction losses within the pump, and wear'of both the sidesealing means and the sides of the gears in contact there- With.' H

I have found that most of the ineffectiveness of fuel pumpslunder vapor lock conditions arises because the pumps themselves are so ineflicient that they are unable to create a sufficiently high vacuumin the presence of vapor to cause the fuel to flow from the tank to the pump, and it is .accordingly a further object of this invention to provide a fuelpump for an internal combustion engine, the pump being of such high volumetric efficiency as to draw fuel from a tank despite the presence of vapor in the pump, even under such relatively low operating speeds of the pump as are encountered when the engine is turned over by a starter.

A feature of this invention isa design of fuel pump for an internal combustion engine wherein the pump is free of pockets. in which vapor may be trapped.

These and other objects and features of this invention will become apparent from the following detailed descriptibn when taken, together with the accompanying drawings in which: 7

Fig. 1 may be considered an elevational view of a pump. madev in. accordance with this invention and designed particularly for use with liquid fuel injection systerns; 1

' of the end cover,

Fig. 2 is a transverse section through the pump taken along line 2-2 of Fig. 1 andin the direction of the ar-i rows at the ends thereof; V I v Fig. 3 is a plan view 'ofthe assembled pump of Fig. 1;?

Fig. 4 is an elevation in section of the pump of Fig. 1 taken along line 4-4 of Fig. 2; i i Fig. 5 is an elevation of thecover plate for the pump of Fig. 1 taken along lines.5-5 of Fig. 2; a I

Fig. 6 is a fragmentary enlarged section of a portion the section being taken along line 6-6 ofFig.5; j

, Fig. 7 may be considered a plan view of a fuel pumpparticularly designed for low pressure fuel systems using a carburetor for mixing the fuel and air; Fig. 8 is an elevation in section of the pump of Fig. 7, the section being taken along line 8-8 thereof and look-'. ing in the direction of the arrows at the ends of said line. I Fig. 9 is an end elevation of the pump of Fig. 7; Fig. 10 is a plan view in section of the relief valve of the pump of Fig. 9, the view being taken along line 1010 thereof and looking in the direction of the arrows. at the ends thereof; and

Figs. 1 1, 12, 13 and 14 show the details of the side sealing plates for'the pump of Fig. 7;

' counterbore 24 adjacent bearing 23, serves to prevent E i B Q the estatio the P F SuIe'eXerted:

dirt from entering the pump and the fluid contents of the pump from escaping out of the pump alongshaft 22 On the .righthand-end of shaft 22, as viewed'in Fig:- I I 2,'is formed a gear 26- disposed in a chamber 27 formed? as a circular: recess inthe end of casting 20. Adjacent-1 gear 26, and meshing therewith, is :a second gear 28' mounted on a stub'shaft 29 one end of which is suitably supported in vhousing 20L For ease of manufacture, gear s' 26 and:28rmay.Ib e"made 'of the Same diameter and Width? Circular recess 27 is made a closed chamber by the application of an end cover 30 to the right hand side (Fig. 2) of housing 20, said end cover being secured thereto by a plurality of machine screws 31 (Fig. 1). Chamber 27 is further partitioned by a shroud 34 into a low pressure or inlet chamber-.32 and a high pressure or outlet chamber 33, said shroud cooperating with the tips of the gear teeth of the

gears

26 and 28 to effect this partitioning. Shroud 34 is of the type disclosed and claimed in my copending application, Serial No, 341,272, filed March 9, 1953, now Patent No. 2,742,862, for Fluid Pump, and comprises preferably a single piece of resilient deformable 'material having elastomeric properties, such as rubber, synthetic or natural, or a combination of the two, of a'thickness substantially equal to the width of the. face of the gear teeth (that is, measured along the axis of the gear) and a configuration such that it will contact the outer periphery 35 of chamber 27 and the tips of the teeth of

gears

26 and 28 adjacent thereto. High pressure chamber 33 is defined, in part, by a groove 36 extending axially of shroud 34 and disposed symmetrically with respect to

gears

26 and 28. The side walls of the groove are exposed to the fluid under pressure in chamber 33, the pressure causing the shroud to be distorted against the outer peripheries of the teeth of

gears

26 and 28 thereby to assist in maintaining a fluid-tight seal between the shroud and the tips of the teeth of

gears

26 and 28.

End cover 30 is formed with an inlet opening 37 and an outlet opening 38, said inlet opening communicating with chamber 32 and the outlet opening communicating with chamber 33'. Inlet opening 37 may be connected by suitable piping or tubing to a tank containing the fluid to be pumped such as diesel oil, and outlet opening 38 may be connected by similar piping or tubing to the fuel injection system of the internal combustion engine with which the pump is to be used. Since the devices to be connected to the pump are not part of this invention, they are not shown nor described in detail herein.

As described more fully in my aforesaid copending application, Serial No. 341,272, shroud 34 contacts the tips of the teeth of

gears

26 and 28 with a very light, but nevertheless firm contact so that the shroud is continually wiped by the gear teeth as the gears are rotated, the wiping action being made possible by the slight deformability of the material of the. shroud.

The sides of the gears are sealed by a pair of bimetallic discs 39 and 40 disposed one on either side of

gears

26 and 28. Each said plate is comprised of a relatively thick sheet of steel 41, 42 to which is welded by pressure under heat, or otherwise, a relatively thin sheet of

bronze

43, 44, respectively. This provides an appropriate material of dilferent composition to run against the steel of the gears to prevent spalling and undue wear of both the bears and the plates. The steel backing provides the necessary strength for the plates.

An opening 45 is provided in plate 39 through which shaft 22 may pass.

Additional openings

46 and 47 are formed in plate 39, opening 46 communicating with low pressure chamber 32, and opening 47 communicating with high pressure chamber 33. An opening 48 in plate 40 establishes communication between inlet opening 37 and low pressure chamber 32, and an opening 49 establishes communication between high pressure chamber 33 and outlet opening 38.

It is contemplated that the fluid under pressure to be pumped will supply a part, at least, of the force necessary to maintain plates 39 and 40 in close sealing contact with

gears

26 and 28. To this end, cover 30. is. relieved over an inverted T-shaped area 50 (see Fig. surrounding outlet opening 38 and overlying pressure chamber 33. As may be observed from Fig. 5, the relieved area overlies approximately 180- of arc of each of the

gears

26 and 28,. including the portion of the gears wherein the teeth. are in mesh with one another.

The boundary of area 50 is defined by a groove 51 in which is disposed an endless ring 52 of elastomeric material, preferably having an unstressed cross sectional configuration of a circle. For this purpose any of the presently commercially available O-rings having the appropriate length, composition and hardness of material can be deformed to take. the shape of groove 51. The depth of groove 51 is slightly less than the diameter of the radial cross section of the O ring, such that the ring is compressed when cover 30 is fastened to housing 20.

It may be observed that fluid under pressure entering area 50 between cover 30 and plate 40 will exert a pressure against said plate 40 in an axial direction relative to shaft 22 thereby urging said plate against the sides of

gears

26 and 28, and that said gears, in turn will be urged axially against plate 39 and will hold said plate 39 against the radial surface 53 of recess 37. By limiting the pressure area 50 to as small a section of the gear size as possible, a satisfactory seal is obtained without an undue amount of friction being developed between the plates and gears, thereby increasing the mechanical efiiciency of the pump.

It is contemplated that, in accordance with the objects of this invention, the pressure of'the fluid leaving the pump through outlet opening 38 will not exceed a predetermined value. This limitation in the output pressure is brought about by the provision of a relief valve 54 communicating with opening 47 in pressure chamber 33. Said relief valve is comprised of a hollow cylinder having one end 55 closed and formed at its exterior with an annular knife edge 56 disposed around the outer periphery thereof. Said knife edge is preferably arranged concentrically with respect to opening 47 and bears against the exposed surface of steel plate 41 to form a seal therewith.

Valve 54 is axially reciprocable in a circular recess 57 in housing 20 disposed with its axis parallel to the axis of shaft 22 and provided with a vent opening 58 communicating with counterbore 24. Circular recess 57 is connected by a passageway 59 to opening 46 in plate 39 and thence to chamber 32 which, as stated previously, is the low pressure chamber in communication with the tank or other supply of liquid fuel. Additional passages 60 and 61 may be provided for the purpose of lubricating bearing 23 and shaft 22. A spring 62, calibrated for the relief pressure desired, is compressed in recess 57 between the bottom of the recess and the closed end 55 of valve 54. Said spring holds valve 54 in fluid sealing engagement with plate 39 until the pressure in chamber 33 exceeds the maximum pressure desired in the fuel line leading from said chamber.

It is contemplated that shaft 22 will be connected to a suitable source of power somewhere on the engine to be supplied with fuel by the pump hereinabove described. When so connected and driven shaft 22 will rotate gear 26 which, in turn, will rotate gear 28. Assuming that the direction of rotation of gear 26 is counterclockwise (Fig. 4) and that of gear 28 is clockwise, fluid will be picked up between the teeth of the gears, confined by shroud 34, and carried to chamber 33 wherein the entrance of a tooth of one gear into the space between adjacent teeth of the other will create a pressure in chamber 33 to cause the fluid to flow therefrom. Said fluid under pressure will act upon end 55 of relief valve 54, and when the pressure exceeds that exerted by spring 62, valve 54 will be pushed off plate 39, thereby opening chamber 33 to passageway 59. The excess fluid thus enters the low pressure chamber 32 and is again circulated through the pump past valve 54 and through passage 59 to low pressure chamber 32. This circulation of excess fluid to maintain a predetermined pressure in the outlet for high pressure chamber 33 continues as long as the demand for the fluid pumped does not exceed the supply. The presence of fluid under pressure. in chamber 33 and in relief area 50. results in pressure of plate 40 against

gears

26 and 28 and of these gears against plate 39, thus creating a seal the internal combustion engine to stop the operation of V the engine, the operation of the engine, either by a push of the vehicle while it is drivingly connected to the engine, or by operating the starter for the engine, will turn the pump gears 26, 28 and eventually clear out all of the air in the system. a f

The form shown in Figs. 7 to.14, inclusive,'is designed for usewithinternal combustion engines using'volatile fuel such as gasoline, the fuelbeing aspirated in a carburetor and fed to the carburetor under a maximum pressure offive pounds per square inch. As shown in Fig.

8, thedevice comprises, in general, a pump 63 made in accordance with the teachings of this invention having a pressure regulating valve 64 and a pressure responsive cutoif valve 65 controlling the output thereof.

Pump. 63 is comprised-ofa housing 66 which extends into an apertured boss 67 in the housing 68 of a' drive source for the pump, such as an engine governor and distributor housing having a geared outlet 69 (Fig. 7), for a tachometer drive or the like. Said'outlet 69 includes a driven gear 70 pinned to the left handend (Fig. 7 )Iof the drive shaft 71 of pump 63. Said shaft 71 drives gear.

72 of the pair of gears constituting the pressure-creating portion of the pump, said pair of gears being in .all we, spects similar to pump gears 26 and 28 of Fig. 4. i The right hand endof shaft 71 as viewed in Fig. .8

is. supported in housing 66 by an antifriction bearing 73 the lubricantfor which is prevented from travelling along shaft 71 to the left into housing 68 by ashaftseal 74 disposed adjacent bearing 73 andinterposed between shaft- 71 and housing 66. Said housing 66 is held in, place relative to housing.68 by a clamp 75, one end of which is received in a groove 76 in housing 66. ,The clamping force is derived from a nut 77 threaded on a stud 78 secured to housing 68 and bearing against clamp 75. Movement of housing 66 in the direction of the clamping force is limited by a shoulder 79 on housing 66 abutting upon a flat surface machined in'the side of housing68.

Y Gears 72 are disposed in a cylindrical recess. 80 opening into the right hand side (Fig; 8), of housing 66,

. recess 80 being covered by a spacer plate 81 and by the housing 82, for the pressureregulating and cutoff'valves 64 and 65. respectively. Between gear-:72 and the bottom surface 83 of recess 80 is disposed ,a side seal .plate 84 made of bimetallic material,the principal portion of the plate being comprised=of 'steel and the portioncontactirig the sides of the gears being bronze or some similar material which will run well against the material of the gearswithout spalling or undue wear. As shown in Fig. 11 plate.84 is provided with an opening 85 through which shaft 71 may extend, and with a second opening 86 through which the stud shaft (not shown) for the driven gear of the pump may similarly extend.

Grooves

87 and 88 ,extendin'g radially from openings 85 and 86,

respectively, along the surface .of the bronze portion to the outer periphery of disc 84 serve to prevent a.build-- up of fluid under pressure between the sides of the gears and the side sealplate as-w ell as to conduct a portion of the fluid to1be pumped to the bearing 73 and to the stud shaft to provide lubrication therefor.

. ,A shroud 89, made of an elastomer' such'as rubber, eithernatural or synthetic or a combination of the two and having satisfactory wear qualities, is inserted in recess 80. btween the gears and .theyhousing. Said shroud may beideutical inevery respect to shroud 3.4 atria-. a

1 Between the'gears 72 and spacer 81 there is disposed 'a" bimetallic side seal plate in the form of a disc 90 ing '91 is provided in plate 90 through which fluid to be pumped is admitted to the inlet side of recess 80. A somewhat, greater than semi-circular opening 92'is formed in plate 90 below opening 91. Said opening .92 is adapted to be filled by a similarly shaped insert 93 (Fig. 13) made of the same material as plate 90 and having an opening 94 therein constituting the outlet opening for the pump. A second opening 98 is provided through which the stub shaft of the driven gear passes. It is understood, of course, that the bronze surfaces of plates '90 and 93 are disposed adjacent the gears 72 to provide a suitable running face therefor.

Overlying plates '90 and 93 is a flexible diaphragm 95, preferably of the same material as shroud 89, having an opening 96 aligned with opening 94 and an opening 97 aligned with opening91. As will be hereinafter described in detail, opening. 97 is-theinlet opening for the pump and hence is connected through suitable conduits and pipes to the source of supply of the fluid being constituting the inlet opening for the pump, a pressure relief valve opening 100, and with a pump outlet opening 101. As shown in Figs. 8 and 14, the portion of spacer 81 overlying plate 93 is relieved to form a chamber 102 into which the fluid under pressure coming from the pumpmay flow. Said fluid under pressure acts upon that portion of diaphragm which overlies plate 93 and serves to'urge such portion, and plate 93, toward the gears 72. -Said gears, in turn, are free to move to the left as viewed in Fig. 8 against side seal .plate 84, and to hold the latter against bottom 83 of recess 80. This results in aneffective seal for the sides of the gear teeth 3 housing 82 may be used to seal all of said passages from the exterior of the pump as well as from one another.

Valve housing 82 is comprised of a substantially cylindrical portion 105 having its axis disposed transversely of the axis of pump shaft 71, a plate 106 spaced from cylindrical portion 105 and abutting on spacer 81, and an intermediate connection portion 107 between plate 106 and cylindrical portion 105. A through bore 108 is formed in portion 105, the bore being closed at its lower end, as viewed in Fig. 8, by a bolt 109 and provided at its other end with spaced bearing bushings 110 and 111 within which is adapted to reciprocate a valve 112. An 0 ring seal 145 is disposed between bushings 110 and 1 11 to prevent,the fluid being pumped from escaping to the exterior of valve 65.

The upper end 113 of valve body portion 105, as

viewed in Fig. 8, is belled outwardly and upwardly and;

having a flange 117 is disposed on diaphragm 115 on the side thereof opposite flange 114, flange 117 being of substantially the same size as flange 114 and being secured to the latter by cap screws 118 which clamp the peripheral region of diaphragm 11,5 'toflange 114.;

The. upper end of valve 112 as viewed in Fig. 8 extends through diaphragm 115 and terminates in a shoalder 119. An apertured plate 120 is placed on the side of diaphragm 115 opposite shoulder 119 and is made to compress diaphragm 115 against said shoulder 119 by a nut 121 threaded on valve 112.

It may be apparent that the flared upper portion of body 105, dished cover plate 116 and diaphragm 115 constitute a pressure responsive motor for reciprocating valve 112 in the cylindrical portion 105 of the valve housing. It is contemplated that the chamber 122 formed between diaphragm 115 and dished plate 116 will contain the fluid the pressure of which is to be utilized to control the operation of valve 112. Chamber 123 on the other side of diaphragm 115 is vented to atmosphere at 124. Access to chamber 122 is gained from the exterior through a threaded opening 125 formed in an appropriate boss located eccentrically of the center of valve 112.

' Cover plate 116 also serves as a limit stop for the upward movement of valve 112 and said valve is constantly urged upwardly against plate 116 by a spring 126 retained between the head 127 of a needle valve 128 and an axially slidable bushing 129 surrounding needle valve 128 and serving to center said valve in the cylindrical portion 105 of the valve housing. The upper end of bushing 129 abuts on the lower end of valve 112 so that the pressure of spring 126 is transmitted directly to valve 112 through bushing 129. It is contemplated that spring 126 will be so selected as to provide the requisite pressure to overcome the total pressure on diaphragm 115 produced by the fluid in chamber 122 up to a pressure of five pounds per square'inch and to yield under total pressures produced by unit pressures in excess of five pounds per square inch.

Chamber 102 adjacent diaphragm 95 is connected to bore 108 by a passageway 130 terminating below bushing 111 and above bushing 129 so that the fluid enters bore 108 around valve 112. Said valve 112 has an axial passage 131 formed therein which extends throughout its entire length and is connected by cross passages 132 in shoulder 119 to chamber 122. A plurality of radially extending grooves 133 is formed across the upper end of bushing 129 and constitute passages for admitting fluid from passageway 130 around valve 112 into bore 108, and from bore 108 through said grooves 133 to the central passageway 131 in valve 112. The fluid may then flow through cross bores 132 into chamber 122 and thence through opening 125 and suitable pipes to the carburetor or other fuel flow regulating device of the engine.

Chamber 102 is also connected through opening 100 in spacer plate 81 to a cylindrical valve chamber 135 in which is axially slidable a relief valve body 136. Said body is hollow and has nested therein a compression spring 137 which is compressed between the bottom of the chamber and the valve and serves to urge said valve continuously against spacer plate 81. Contact between valve body 136 and spacer plate 81 is limited to a knife edge 138 formed around the periphery of valve body 136. This insures continuous contact with the plate around the periphery of the valve and also to provide a larger area of the valve against which the fluid under pressure issuing from opening 100 may act. The chamber behind valve body 136 is vented by a small drilled passageway 139 which connects the chamber to a vent chamber 140 serving also as the vent for the valve body 136. Spring 137 is setfor a maximum fluid pressure of 20 to 30 pounds per square inch so that when the pressure of the fluid in chamber 102 exceeds the maximum spring pressure, valve body 136 will be lifted oif its seat against the action of spring 137 andwill allow fluid to escape into ventchamber 140 from which it may be conducted through a suitable passageway 141 (Fig. back to the fuel supply tank.

8 The fiiel inlet opening is formed in a boss 142 (Fig. 9) disposed in the side of cylindrical valve body portion and the fuel is conducted through a transverse opening 143 therein through passage 144, opening 99 in spacer 81, opening. 97 in diaphragm 95, and opening 91 in side seal plate 90 to the inlet chamber for the pump.

One of the conditions under which the pump of Figs. 7 to 11 may be required to operate is that obtaining when the entire fuel system between the pump and the engine is substantially dry and the engine is being turned over by its starter mechanism. During this relatively slow rotation of the engine and its distributor shaft, gear 70 and shaft 71 will similarly be rotated at a relatively low speed. Due to the high volumetric efliciency of the pump, however, a definite vacuum will be established in the intake side of the pump, thereby reducing the pressure in the intake passages below atmospheric and causing fuel to start flowing from the tank through the passages to the pump. Meanwhile, on the pressure side of thepump the air will be pressurized and will force its way to chamber 102, passageway 130, radial grooves 133 and central passage 131 through cross bores 132 into chamber 122. From chamber 122 it will be forced into the float chamber of the carburetor which at this stage is empty, and accordingly the float valve is open, thereby allowing the air to pass freely out into the atmosphere. Some, of course, will find its way into the engine because of the suction created therein and in the intake manifold connected to the carburetor.

When the liquid fuel reaches the pump from the tank it will take the same path taken by the air as described above, except that it will remain in the float chamber and will gradually fill the chamber. When the float chamber is filled, the float valve therein will close and pressure will then be built up in chamber 122, forcing diaphragm and its associated valve 112 downwardly against needle valve 128. When said needle valve 128, passes radial grooves 133 and finally closes said passages, pressure in passage 'leading to grooves 133, and in chamber 102 will increase until the pressure against valve 136 overcomes spring 137, and the fluid is then vented through chamber and passage 141 back to the tank. Since the inlet and outlet passages are separated there is no recirculation of the fluid, whether liquid or vapor, and hence the conditions under which a vapor lock is created are substantially eliminated or avoided. Any small air bubbles entering the pump with the liquid will be moved on out through the pump to the carburetor and since the condition of the carburetor is governed by a float valve which in turn'is dependent upon the amount of liquidpresent and not at all upon the quantity of air or vapor which may pass therethrough, the float valve will remain open until the air bubbles escape and the float chamber is filled with liquid fuel. 1

It may be apparent that both forms of pump described above provide a positive movement of air vapor, liquid fuel, or combinations of these fluids through the pump and henee the, conditions under which a vapor lock occurs are minimized, if not altogether eliminated. The pumps are small, require little power, and are durable.

It is understood that the foregoing description is illustrative of preferred embodiments .of this invention and that the scope of this invention is therefore not to be limited thereto but is to be determined by the appendedclajms. 4

I claim:

A ea t p pump c mp i a housing having a cylindrical recess therein, a pair of intermeshing gears dispose w thin sa d ece ean for driving 1 of said gears, ar d means for dividing the recess into inlet and outlet eharnbers with respect to the gears, said means Qmprising a resilient deformable shroud disposed within said recess and contacting the tips of the gear teeth over less than of arc of each gear, a side seal plate adapted to contact the sides of the gears on one side thereof, and a side seal plate for sealing the other side of said gears, said second-mentioned side seal plate extending across said cylindrical recess and having an open ing therein overlying the outlet chamber of the pump, an axially movable insert inside the opening, means coextensive with the recess and contacting the housing around the periphery of the recess for sealing the insert with respect to the said second-mentioned side seal plate, and means for subjecting the side of the insert opposite the side contacting the gears to the pressure of thefiuid in the outlet chamber.

2. A pump as described in claim 1, said means for sealing the insert with respect to the plate comprising a diaphragm overlying the plate and insert, a rigid cover plate for the recess, and means for securing the cover plate, diaphragm and second-mentioned side seal plate to the housing, the pressure from the outlet chamber acting upon the diaphragm to urge it against the insert.

3. Apparatus for transferring fluid from a source of supply comprising a housing having a cavity therein opening on a side of the housing, intermeshing rotatable pump gears in the cavity, means sealing ofi portions of the gears to establish inlet and outlet chambers in the cavity for the fluid, a spacer plate overlying the sealing means and having two outlet openings in communication with the outlet chamber and one inlet opening in communication with the inlet chamber and with the course of supply, means on the housing establishing fluid communication between the inlet chamber and one of the two outlet openings in communication with the outlet chamber through the source of supply, and a pressure relief valve in the said one of the two outlet openings normally closing said'one of the two outlet openings.

4. Apparatus for. transferring fluid from a source of supply comprising a housing having a cavity therein opening on a side of the housing, intermeshing rotatable pump gears in the cavity, means sealing 'otf portions of the gears to establish inlet and outlet chambers in the cavity for the fluid, a spacer plate secured to the side of the housing over the cavity and overlying the sealing means, said spacer plate having two outlet openings in communication with the outlet chamber and one inlet opening in communication with the inlet chamber and with the source of supply, a second housing secured to the first housing over the spacer plate and having a passage communicating one of said outlet openings with the inlet opening through said source ofsupply, and valve means in the second housing normally closing the said passage and responsive to the pressure of the fluid in the outlet chamber for limiting the pressure of the fluid in the outlet chamber.

10 5. Apparatus as described in claim 4, said second housing having an exterior opening and a passage connecting the other of said outlet openings with the exterior opening, and a cut-01f valve in the second housing for closing the other of said outlet openings, said cut-off valve being responsive to the pressure of the fluid in the exterior opening.

6. Apparatus for transferring fluid from a source of supply comprising a housing having a cavity therein openin on a side of the housing, intermeshing rotatable pump gears in the cavity, means sealing off portions of the peripheries of the gears and dividing the cavity into. inlet and outlet chambers, a plate overlying the cavity and having an openingexposing the outlet chamber and adjacent portions of the gears and sealing means, a second plate in the opening, a resilient diaphragm extending over the cavity including the second plate, and means establishing a third chamber exterior to the diaphragm overlying at least a portion of the said opening in the plate, therebeing, aligned openings in the second plate and diaphragm communicating with the third chamber exterior to the diaphragm to establish unit pressure in the third chamber substantially equal to that in the outlet chamber whereby to urge the diaphragm and second plate against the gears, and sealing means to provide a seal between the inlet and outlet chambers.

7. Apparatus for transferring fluid as described in claim 6, said means establishing a third chamber comprising a spacer plate having a pair of outlet openings leading from the third chamber, a second housing secured over the spacer plate, and a valve in the second housing movable against the spacer plate to block one of said outlet openings, said housing having a passage connecting the said one of said outlet openings with the inlet chamber through the source of supply, such that when the valve is moved to uncover the said one of said outlet openings, fluid is by-passed from the outlet cham her to the inlet chamber.

References Cited in the file of this patent UNITED STATES PATENTS Deska Nov. 19, 1957