US2742862A

US2742862A - Fluid pump

Info

Publication number: US2742862A
Application number: US341272A
Authority: US
Inventors: Oscar H Banker
Original assignee: New Products Corp
Current assignee: New Products Corp
Priority date: 1953-03-09
Filing date: 1953-03-09
Publication date: 1956-04-24
Anticipated expiration: 1973-04-24

Description

A ril 24, 1956 o. H. BANKER FLUID PUMP 4 Sheets-Sheet 2.

Filed March 9, 1953 39 fizz/6% 5 dam/115a P 1956 o; H. BANKER 2,742,862

FLUID PUMP Filed March 9, 1953 4 Sheets-Sheet 5 BY Zaw/oz/ZJM WW April 24, 1956 o. H. BANKER 2,742,862

FLUID PUMP Filed March 9, 1953 4 Sheets-Sheet 4 JNVENTOR.

FLUID PUMP Oscar H. Banker, Evanston, Ill., assignor to New Products Corporation, Chicago, 111., a corporation of Delaware Application March 9, 1953, Serial No. 341,272

Claims. (Cl. 103-126) free radial clearance at the internal peripheral surface of the housing; thereby economizing in cost of manufacture by eliminating a close fit of the around the gears.

A further and more specific object is to provide a gear pump of the sort referred to above, wherein fixed, hollow, fluid pressure responsive members of resilient ma terial are associated in sliding sealing relation to a side .and/or peripheral surface or surfaces of the pump gears fectively sealed at the high pressure discharge zone, yet

liberal clearance exists between the unsealed portion of the gears and the housing pumping cavity other than its discharge zone.

Still another specific object is to provide an improved self-sealing and self-compensating gear pump featuring a resiliently expansible unit in sliding sealing engagement with side surfaces of the meshing pump gears, as described above, which unit has an internal pressure cavity of predetermined shape and size, substantially overlapping the sides pressure discharge zone adjacent their meshing teeth. The internal area of a wall of the cavity facing the gears is substantially greater than theexternal area of the unit which is exposed at the pressure zone, so that a pressure diiferential is created to maintain the unit in tight sealing engagement with the gear side surfaces, for the purposes described in the preceding paragraphs.

A still further object is to provide an improved gear pump of the sort described above featuring, in certain embodiments thereof, a shaped discharge throat or dis charge member of resilient material adjacent the pump discharge opening, the member being shaped to provide of the gears outwardly of a high' arcuate gear tooth sealing shoulders positioned for ra dial wiping and sealing engagement with the teeth of the pump gears, over a substantial arc in each case. The shoulders are thrust into radial sealing relation gears by the discharge pressure, which is in most inment with the gear housing of the pump.

Yet another object is to provide a self-sealing gear pump incorporating a radially acting, gear tooth sealing member in combination with a gear side surface sealing member, both members being urged to sealing engagement with the gears by pressure equal to the pump discharge pressure at the meshing gear teeth zone.

A further object is to provide a pump which, in other modifications thereof, has arcuate concave tooth sealing shoulders thrust into gear teeth under the plied discharge pressure at the high pressure zone.

In still another modification, peripheral gear tooth sealing action is performed by a pair of laterally spaced, internally chambered, concave surfaced sealing shoulders which occupy opposed corners of the housing interior; the shoulders are urged into engagement with the teeth by internal pressure equal to the pump discharge pressure.

Yet another embodiment according to the invention contemplates the use of an arcuate gear tooth sealing shoulder member or members yield-ably urged radially against the gears by an adjustable spring biasing arrangepressure regulator, by enabling the sealing member or members to yield at a desired pre-set spring setting and thus by-pass liquid from the high pressure discharge zone, of the pump cavity. I

In any of the embodiments, it is an object to provide a gear pump as described in the preceding paragraphs in which the sealing members which engage the pump gears, particularly the radially acting members, may be metal clad to resist wear on the gear engaging surface or surfaces, and to prevent jamming into the gear teeth. Use of such wear means may be dispensed with in low pressure pumps, but is practically indispensible inheavy duty types.

The foregoing statements way of the nature of the invention. Other and more specific objects will be apparent to those skilled in the art upon a full understanding of the operation of the improved pump.

Various modified embodiments of the invention are presented herein for purpose of illustration. It will be appreciated that the invention may be incorporated in still other modified forms coming equally within the scope of the appended claims.

In the drawings:

Fig. 1 is a side elevational view of the improved pump, in accordance with one embodiment thereof;

Fig. 2 is a view in longitudinal cross section along a line generally corresponding to line 2-2 of Figs. 1 and 4, generally showing the lateral sealing member for the pump gears;

Fig. 3 is a cross sectional view through the pump on line 3.3 of Fig. 2, illustrating details of the'improved, side-acting gear sealing arrangement, and of the discharge side of the pump;

Fig. 4 is a view in transverse section along line 4-4 of Fig. 3, further showing the improved discharge throat sealing provisions of the invention;

are indicative in a general construction and p Fig. is a view in front elevation of the side gear surface sealing member of the improved pump, the member being viewed as from line '5-5 of Figs. 2 and 3;

Fig. 6 is a view in transverse section, similar to Fig. 4, showing a metal clad discharge throat sealing member in accordance with a slightly modified adaptation of the invention;

Fig. 7 is a view in'transverse vertical section, partially broken away, and approximately as viewed along line '7-7 of Fig. 8, illustrating pump housing components of a modified form of the invention, particularly as regards the radially acting gear tooth sealing provisions adjacent the pump discharge side;

Fig. 8 is a view in vertical longitudinal section along a line corresponding to line 8-8 of Fig. 7;

Fig. 8A is a view in vertical section along1ine8A-8A of Fig. 7;

Fig. 9 is a view similar to Fig. 7, and as viewed along line 9-9 of Fig. 10, showing a further'modified embodiment of the invention involving a block-like discharge throat sealing device;

Fig. 10 is a view in longitudinal vertical section approximately along line 10-40 of Fig. 9;

Fig. 11 is a view in transverse section, along a line corresponding to line 1'111 of Fig. l2,illustrating yet another modified embodiment of the invention, featuring laterally spaced, radially acting gear teeth sealing shoulders;

Fig. 12 is a view in line 1212 of Fig. 11;

Fig. 13 is a view generally similar to Fig. 11 showing a still further modified form of the invention, featuring an adjustable spring pressure regulating action at the radially acting gear tooth sealing surfaces; and

Fig. 14 is a view in vertical longitudinal section along a line corresponding to line 1'4-14 of Fig. 13.

Although the above figures disclose pumps of a wellknown sort having gears with external meshing teeth, the principle of the invention is also adaptable to a gear pump of the outside-inside type, featuring a larger, internally toothed gear and a smaller, externally toothed gear in mesh therewith.

Referring to Figs. l-6 inclusive, ofthe drawings, the reference numeral 10 generally designates a housing or casing for the improved pump in accordance with one form of the invention. It consists of an appropriately chambered gear housing and intake-discharge passage member or body 1 1, at'the'right, having intake and

discharge fittings

12, 13, respectively, communicating with its interior at vertically spaced levels. closure and bearing plate 14, at the left, is bolted to housing body 11.

Housing 10 provides a pump gear cavity 15 to which liquid is supplied through an intake passage 16 in' alignment with intake fitting 12. Meshing

pump gears

17, 18 are located in this cavity, their shafts '19 being journalled by roller bearings in bearing receiving openings 20 at either side of the gear cavity. Appropriate cages mount the bearings in the openings, in well known fashion.

It will be noted, particularly by reference to Fig. 4, that a substantial radial clearance exists between the outer extremities of the teeth of gears "17, 18 and the inner peripheral wall of housing cavity '15. Close tolerance machining and fitting of parts is thus eliminated. The pump is driven through a shaft 21 on gear 18, as illustrated in Fig. 2, leakage at this point being prevented by the use of a conventional seal 22.

In accordance with this form of the invention, and as best illustrated in Fig. 4 of the drawings, the teeth of longitudinal vertical section along

gears

17, 18, adjacent the central, restricted, discharge zone or space Z of pump chamber 15, have sliding,.pressure sealing engagement with laterally spaced arcuate shoulder surfaces 23 of a discharge throat insert 24 of special shape and non-metallic composition. Referring An end or side to Figs. 3 and 4, insert 24 is provided with an intake throat 25 between shoulder surfaces 23, which throat opens downwardly from high pressure discharge zone Z. Throat 25 communicates downwardly with an enlarged, generally cylindrical interior 26 of insert 24, and this space in turn opens laterally, through a port 27 of substantial size in the insert, to a discharge passage 28 in housing body 11. The insert 24 is an elastomer unit fabricated of rubber or like elastic or rubber-like material and is snugly fitted in a recess in the body which downwardly adjoins its gear pumping chamber 15. Other gear side sealing means, to be described, coact with insert 24 in the automatic, self-pressurized sealing of

gears

17, 18 in accordance with the invention. However, a description of the rest of the pump body structure which adjoins the discharge passage 28 appears in order in the interest of continuity. Illustration and description of such structure are dispensed with in connection with the other modifications shown in Figs. 7-14, but it is to be understood that similar provisions will be associated with those forms.

Housing body 10 is provided, in alignment with the passage 28, with an enlarged cylindrical bore 29 to which the passage opens. This bore receives a fixed tubular valve insert sleeve which'is generally designated 30. The insert has a plurality of radial ports 31 leading to a transverse by-pass duct 32 in the body, by which excess liquid may be returned to intake passage 16. This is done under the control of a hollow, centrally apertured pressure regulator plunger 33 slidably mounted in the valve sleeve 30.

Plunger 33 is adapted to yield rearwardly against the force exerted by its internal biasing spring 34, exposing radial ports 31 so that-part of the liquid is by-passed back to the pump intake under a condition of excess pressure.

Valve 'sleeve has a further radial passage or passages 35 and an annular groove, whereby its hollow interior is communicated with a transverse pressure relief passage 36 in the valve body. Emergency flow of liquid through'passage 36 to intake passage 16 is controlled by a ball check 37; this is held in sealing position by a biasing spring 37 encircling a stem 38 threadedly engaged with housing body member 11. The force of spring 37' exceeds that of plunger biasing spring 34-. Ported valve sleeve 30 is sealed in bore 29 by annular Orings in known fashion, and the sleeve is held in place in the bore by a split snap ring 40.

The normal discharge flow of the pump is through passage 28, a central aperture 39 in the inner radial face of plunger 33 and the plunger interior, to discharge fitting 13, being regulated and controlled by the plunger check valvea'nd by-pass means just describcd.

As indicated above, there is associated with the resilient discharge throat insert 24 further means to provide aside sealing of the

gears

17, 18; such means takes the form of a plate-like unit, generally designated 41, which is best illustrated, per se, in Figs. 2, 3 and 5 of the drawings. Its relation to the gears and insert 24 is also indicated in 'Fig. 4.

Unit '41 comprises a flat metallic wear plate or disk 42 shaped in general conformity with the outline of the gear cavity 15, as can be seen by comparing Fig. 5 with Fig. 4. An'approximately semi-circular notch 43 is formed at the upper center of this member to fully expose intake passage 16 to the pump cavity. A hollow pressure responsive member 44 of molded rubber, or other elastic, rubber-like'material is fitted in a correspondingly shaped recess in the rear of plate 42, and may be vulcanized thereto. Plate 42 is provided with laterally spaced cir cular openings 45 adapted to receive bushings 46 (see Figs. 2 and 4) in which the gear shafts 19 are received. These bushings laterally confine the member 44 against the inflativeforce normally present in its interior, as it is otherwise-confined by the plate recess.

Member 44 is small in relation to the area of the associated plate 42. It is specially molded inan'outline like that shown'best in Fig. 5. It is ofrelatively small "internal volume, for quick pressurization; nevertheless, it is of sufiicient size that its forward wall 49 which has surface engagement with plate 42' will exert'force on the latter over an area laterally overlapping the side surfaces of

gears

17, 18 substantially, as shown in Fig. 4, i. e., laterally outwardly of pressure zone -Z.' =.-'Discharge pressure is communicated with the interior 48' of 'the sealing unit pressure member 44 through asmall opening 50 in plate 42 and the wall 49 of member'44. t

It is seen from the foregoing :that a differential exists between the hydraulic force of the-discharge. pressure zone Z, acting in a direction tojurge unit 41. away from the

gears

17, 18, and an opposite-force, attributable to the same pressure and acting within-member 44 to urge plate 42 into sealing engagement withthe gear surfaces. The greater area is exposed to'the discharge pressure; it increases as the dischargepressure of the pump increases. The rear wall of member-44 isleft mostly open for molding'purposes, but the internal pressure on a rear inturned perimetral lip 51 is sufficient to insure against zone, which inany event would not be particularly objectionable, maintaining the member firmly against the surface of casing body'll which it-rearwardly abuts v V I. Figs. 3 and 4 of the drawings show that-the discharge pressure zone Z is defined by the' casing end plate 14, theplate 42 of side unit.41,:and the vertical space between the fully meshed gear teeth, at the top of the zone, and the teeth which wipe -past the shoulder surfaces 23 of throat insert 24. The pressure in throat insert 24 continually urges the sealingshoulders' 23 against the peripheral surfaces of the gear teetht It alsocontinually the insert, specially designated 52 and 53' in Fig. '3, against the'casing end plate l4a'nd body 11, respectively. There-is thus a dual hydraulic pressure acting at the verticaloverlap of insert 24 and side sealing unit 41,:preventing leakage at this overlap area. 7 v

.The improved pump is eflicient in operation and very economical to manufacture. HandI-cranking alone, of its power input shaft has produced an instantaneous discharge a'ta pressure as high as 50gpounds per square inch. In an actual run it was found that'operating pressure within member 44 causes" itsouter -walls to bulge-and thereby exert greater, wedge-like force on the 'outer portions of the wear plate 42.: This seals'the gears even more effectively than the direct central transverse force. Furthermore, since the gears are free andclear'in cavity 15 except at zone Z, a back pressure-cannot be built up to effectively oppose the pressure at the sealed area. Throat insert 24 is shown in Fig. 4-as a one-piece, unsheathed elastic unit, its shoulder 23 in'idirect contact with

gear'teeth

17, 18. This is satisfactory for low pres sure pumping. However, metal ear-elements'should be bonded to the shoulder surfaces for high pressure, heavy duty performance, and Fig. 6 shows such a sheathed insert, here designated 24', the wear plates being numbered 54. In other respects,the unit'24' is assembled with other pump components in the identical way described above and shown in Figs. 1 hence it is not deemed necessary to repeat the illustrationor description. It may be assumed that the-insert 24 shown in Figs. 3 and 4 represents companion insert 24, in its intended setting in a comparable high pressure or heavier duty pump. Corresponding parts are designated by corresponding reference numerals, primed. V Figs. 7 and 8 show a modified adaptation of the principle of the invention, particularly 'as'it relatesto the peripheral sealing of the gear teeth of a pump'adjacent its discharge, high pressure throat zone or space. related provisions have been omitted from Figs. 7 and 8 for; the sake of simplicity. It maybe :assumed that if such provisions are desired, they may takethe form illustratedin Figs. 2 and 3 of the drawings. The same is true of the other modifications illustrated in Figs. 9 and 10, in Figs. 11 and 12, and in Figs. 13 and 14, respectively.

Referring to Figs. 7, 8 and 8A, a hollow, chambered casing body 55 and end plate 56 enclose a shaped pumping cavity '57 in which pump gears 58, 59 are rotatively mounted, in an entirely conventional Way, or as illustrated in Fig. 2. A metallic side sealing plate 60 engages one surface of gears 58, 59, and a resilient cushion disk 60' is interposed between plate 60 and casing end plate 56. Plate 60 is shaped in conformity with the upper contour of a block-like metallic sealing member 61 of width slightly greater than the gears, and fits above that block in face engagementwith the gears. It serves as a radial spacer for sealing block 61 as well as a surface wear member, as will be described. Sealing member 61 is provided with arcuate sealing shoulders 62, across which the teeth of gears 58, 59 wipe over a considerable angular sweep; and the shoulders 62 are spaced on opposite sides of a downwardly extending pressure passage 63 in member 61. Passage 63 vertically communicates the high pressure discharge zone- Z in pumping cavity 57 with a pressure plunger cylinder 64 formed at the bottom of pump body 55, in vertical alignment with the intake passage 65 to the cavity 57. A cupped plunger 66 and leather anti-extrusion disk 67 act upwardly in this cylinder against the lower surface of sealing member 61. If desired, a coil compression spring 68 may be provided to supplement hydraulic pressure in cylinder 64 urging the plunger and member 61'upwardly.

The side of the pump cavity 57 opposite shaped wear plate 60 is recessed at 71 for the reception of a hollow resilient, rubber-like pressure member 69 which is generally similar in structure to member 44 of unit 41. A metal, gear face wear plate 70 which, like plate 60, is shaped in conformity with the upper surface of sealing block 61, is disposed inwardly of member 69.

Plates

60 and 70 are both fitted above the shoulder surfaces 62 of member 61 and are received on the bushings 79', so that in sealing the side surfaces of gears 58, 59 they at the same time act as spacers to limit the upward travel of sealing block 61 in radially sealing the gear teeth, as shown in Fig. 8A.

Radial tooth sealing block 61 is milled to provide a groove 73 opening laterally to the discharge passage 72 of easing body 55. Communication is sage through an opening 74 in hollow pressure member 69.

' The operation of the embodiment of Figs. 7 and 8 is believed to be obvious, in the light of the description in connection with Figs. 1 through 6. Plates the side surfaces of the gears portion and at its lower portion bears against the side of sealing block member 61 to assist in scaling in this area. Discharge pressure in zone Z is communicated through passage 63 to the cylinder 64 beneath the sealing block, urging the same upwardly. Coil spring 68 maintains sealing action, as when the pump is not in operation, or at very low pressure operation in which the peripheral engagement of the gear teeth with concave shoulders 62 may not be sufficient to insure sealing at these surfaces.

The form of the invention illustrated in Figs. 9 and 10 putsthe principle of the invention into practise in a slightly different waythan the forms illustrated and de scribed above. That is, internal hydraulic pressure on a sealing member which acts radially against the peripheries of the gear teeth is replaced by hydraulic discharge pressure acting externally on an elastically deforma able sealing member. This causes the concave tooth sealing shoulder surface or surfaces of such member to mold themselves more tightly to and sealingly engage the outer tooth surfaces. The form of Figs. 9 and 10 is primarily intended for low pressure pumping, in which the danger of jamming an elastic .sealing surface in the :gearteeth is :not present.

Referring to Figs. 9 and 10, a side wear plate '76 and a side wear .plate and sealing unit 77 are associated 'with opposite sides of a pair of meshing gears 78, 79 sin a pumping cavity 80. The cavity is defined by a casing body 81 and end plate 82, much in thesame way asshown in Figs. .2 and 3; further illustration and description in this regard can be dispensed with. The gear engaging wear plate of unit 77 is designated 83; its hollow, resilient pressure member is designated :84.

A solid, elastomer thrust block 85 is employed to exert peripheral sealing action on the teeth of gears 78, .79. This type sealing member, in a crescent-shaped outline, may also be used as a sealing unit in an insideoutside type gear pump molding itself .to and wiping against the external and internal meshing gear teeth under the discharge pressure of the pump.

-As shown, member -85 is molded in block-like outline of an elastic, flowable material, such as rubber, synthetic rubber and the like, and a rigid metallic backing plate 86 rearwardly sustains the same. The thus constituted sealing unit'is received in a bottom recess 87 adjoining pumping cavity 80 which is coextensive with the width of the gears. Elastic block 85 is laterally engaged at its sides, as-are the

gears

78, 79, by the side plate 76 and the plate 83 of pressure unit 77.

Resilient sealing block 85 has concave shoulders 88 in peripheral wiping engagement with the teeth of

gears

78, 79, those shoulders being under slight initial compression to seal against static leakage or leakage or very low pressure operation. The block is also formed to provide a medial recess 89 between these shoulders, in axial alignment with the dischargepassage of housing body 81.

The inherent fiowability or moldability of the material of sealing block 85, under the compression of the discharge pressure in zone Z, enables the shoulders 88 to maintain effective sealing engagement with the gear surfaces when the pump is in operation. The block molds itself snugly to the tooth periphery for this purpose. However, this arrangemcnt is best suited for low pressure pumping installation, for if the'elastic material of block 85 is excessively compressed it tends to jam into the space between the teeth, or else to wear at an unduly high rate.

The embodiment of the invention illustrated in Figs. 11 and 12 adopts the principle of an internally pressurized gear tooth sealing unit construction, as in forms of Figs. 1 through 6 and Figs. 7 and 8, but in a somewhat different setting. Here a pair of separate, laterally spaced, metallic sealing shoulders 90 are disposed, respectively, at opposite bottom corners of a pump gear cavity 91 in a pump casing 92, the cavity being closed by an end plate '93. A side sealing plate 94 is interposed between end plate 93 and the meshing gears 95, 96, and a side pressure-sealing unit 97 is disposed in sealing relation to the opposite side surfaces of the gears. Unit 97 is composed of a wear plate 98 and a hollow resilient member 99, both located ina recess in casing body 92, as in the last described em bodiment of the invention.

Each of the rigid metal sealing shoulders '90 is shaped to provide an arcuate sealing surface 100 :of substantial length, a rear corner pressure cavity '101, and a horizontal passage 102 leading to that cavity from a high pressure discharge zone Z of the pumping chamber v9-1. I A cup "plunger or disk 103 is disposed in the pressure cavity 101 to seal the latter when it is pressurized, the disk :being rearwardly engageable against the side wall of the pump chamber 91 under this condition. Shoulder members 90 are thus thrust laterally into engagement with the teeth of gears 95, '96 for the desiredsealing action. The shoulders-are laterally engaged, along with

gears

95, 96, by the side wear

plates

94, 98, as in the preceding embodiment.

The further modified adaptation of the invention illustrated in Figs. 13 and l4incorporates an improved pressure regulator feature enabling the pump to be set for a predetermined-maximhmpressnre discharge, and :to by. pass .pressuretabove this critical ,pre-set pressure so that the toutpu'tiof the pumpiis uniform in this regard. .In this form a block-like, tooth periphery sealing element :memher 104 is provided, which is fabricated of rigid metallic material. lit isdtaped to. provide spaced arcuate shouiders 105 engaging :the teeth of

gears

106, 107 mounted .for rotation in-agpunping-cavity .108 provided by easing body. 109 and end'plate 110.

Member 104 is urged zfor radial sealing engagement by a regulator spring unit, generally designated 111, to be hereinafter'described. {It ,is :sealingly engaged at one side thereof 'bya wear plate 112 and at the other side thereof by :the pressure sealing unit 113. Unit 113 is composed of afurther wear plate. :114 and a hollow, resilient, nonmetallic member 115,'rmd is practically identical to the sealing units 77 vand9r7 previously described.

Regulator spring unitldl comprises a vertically di'sposed tubular spring housing 116 having an upper,-reduced diameter extension 1'17 which is threadedly mounted in the lower sideofthe body 109 of the gear casing, in vertical alignmentwith the center of the pumping cavity 108. Astana-1'18 slidahly received in the bore of ex tension 1177, an D ring 119 being mounted in a groove in the stemitn engage the bore for sealing purposes.

A flanged sleeve or collar 120 is threaded on stem 118 within spring housing .116, and a coil spring 121 upwardly abuts against thefiange of sleeve 120. This spring is rearwardly sustained by an adjustable nut 122 threaded in vthe lower end-of housing 116. Stem 1=18has at Kent 123 in its lower :end by. which it may be rotatively adjusted.

The compression of spring 121 may be pre-set as desired by screwing stemq118 in sleeve 120, whereby the latter exerts, through the force onisealing member 104. This predeterminedly urges the member against the teeth of

gears

106, 107. When the hydrauliepressure in discharge zone Z acting on memher 104 passes acritical, predetermined value, it displaces the latter downwardly against the preset force of spring- 12-1, and apart of the liquid is by-passed between the gear teeth and the sealing surfaces 105 to the intake side of 'pump cavity at the desired value, regulated as desired by appropriate adjustment of the spring force.

Thus a pressure regulator feature is incorporated in agear-pump having the improved sealing provisions of the invention Asia the case of all of the various embodiments illustrated and. described, a gear pump .is provided which is automatically sealed by simple means which eliminate 'the'need-for close tolerance machining andinterfitting of parts. Yet high pressures are developed at relatively low speeds of gearrotation. Hence the pump may be designed in small and very compact sizes to do work heretofore-considered to be satisfactorily done only bylpumps =of materially greater cost, both as regards inputand the cost of manufacture in an adequately large size for a-specified job- It -is evident that theapressure regulator feature shown in Figs. .13 and 14 may also be afforded in the embodiment of the pump shown in Figs. 7 and .8. In such an arrangementthe dome of the spring should be only sufficient to create-a balance of the opposing forces in zone 1 and in the plunger cylinder. .ShOl'lld the discharge pressure acting to urge the sealing throat toward the gears become excessive, representinganundue load on a shaft or bearing, the etfectcanbeotfset by a reversal of rotationof the gear. The intake then becomes a discharge and the force of the spring, now opposed by discharge pressure, can be set to-produce the desired radial force.

I claim:

.1. A geanrmlmp pumping earthy-and having intake and discharge passages communicating :with amid rcavity tatalily mounted i'n the latter, said cavity having a dis :stem, a desired upward spring- 108.. ,This maintains discharge pressure comprising a housing providing a" and meshing gears ro-' charge pressure zone remote from said intake passage, which zone opens to said discharge passage, a discharge sealing-unit partially defining and subject to pressure in said zone, said unit'including a sealing member provided with a sealing surface yieldably engaging the peripheries of gear teeth approaching said zone, and means for effecting a seal between said member and the side surfaces of the gears, said means including discharge pressure responsive means associated with said member to maintain said member in sealing engagement with respect to said housing whereby said discharge pressure zone is effectively sealed.

2. A gear pump comprising a housing providing a pumping cavity and having intake and discharge passages communicating with said cavity and meshing gears rotatably mounted in the latter, said cavity having a discharge pressure zone remote from said intake passage, which zone opens to said discharge passage, a discharge sealing unit partially defining and subject to pressure in said zone, said unit including a sealing member provided with a sealing surface yieldably engaging the peripheries of gear teeth approaching said zone, and means for effecting a seal between said member and the'side surfaces of the gears, said means including discharge pressure responsive means associated with said member to maintain said member in sealing engagement with respect to said'housing, and a further sealing member maintained by saiddischarge pressure in sealing engagement with the side surfaces of said gears whereby said discharge pressure zone is effectively sealed.

3. A gear pump comprising a housing providing a pumping cavity and having intake and discharge passages communicating with said cavity and meshing gears rotatably mounted in the latter in loose fitting relation thereto, said cavity having a discharge pressure zone remote from said intake passage, which zone opens to said discharge passage, a discharge sealing unit partially defining and subject to pressure in said zone, said unit including a sealing member provided with a sealing surface yieldably engaging the peripheries of gear teeth approaching said zone, and means for effecting a seal between said member and the side surfaces of the gears, said means including discharge pressure responsive means associated with said member to maintain said member in sealing engagement with respect to said housing, and a further sealing member maintained by said discharge pressure in sealing engagement with the sides of said gears whereby said discharge pressure zone is effectively sealed.

4. A gear pump comprising a pump casing providing a pump cavity having meshing gears rotatable therein and having intake and discharge passages communicating therewith, said gears in part defining a high pressure discharge zone of said cavity at the meshing teeth thereof, said discharge zone being further defined by a unit provided with a sealing surface in yieldable engagement with the peripheries of gear teeth approaching said zone, and opposed side walls in sealing engagement with the sides of said gears, one of said side walls including deformable discharge pressure responsive means to urge a side surface of said unit in sealing engagement with the opposite side wall whereby said high pressure discharge zone is effectively sealed.

A gear pump comprising a pump casing providing a pump cavity having meshing gears rotatable therein and having intake and discharge passages communicating therewith, said gears in part defining a high pressure discharge zone of said cavity at the meshing teeth thereof, said discharge zone being further defined by a unit provided with a sealing surface in yieldable engagement with the peripheries of gear teeth approaching said zone, and opposed side walls in sealing engagement with the sides of said gears, one of said side walls including deformable discharge pressure responsive means to urge a side surface of said unit in sealing engagement with the opposite side wall, said means comprising a hollow member of resilient material having a pressure wait facing said gear side surfaces which is of an area suflicient'to overlap said gear surfaces radially outwardly of said meshing gear teeth, said means having an opening through said pressure wall communicating the interior of said hollow member with said high pressure zone to impose the dischargepressure of said zone on a part of said pressure wall overlapping said gear side surfaces and thus urgesaid last side wall in sealing relation to said vgear side surfaces whereby is effectively sealed.

6. A gear pump comprising a pump casing providing a pump cavity having meshing gears rotatable therein and having intake and discharge passages communicating therewith, said gears in part defining a highpressure discharge zone of said cavity at the meshing teeth thereof, said discharge zone being further defined by a unit pro.- vided with a sealing'surface in yieldable engagement with the peripheries of gear teeth approaching said zone, and opposed side walls in sealing engagement with the sides of said gears, one of said side walls including deformable discharge pressure responsive means to urge a side surface of said unit in sealing engagement with the opposite sidewall, said means comprising a hollow member of resilient material having a pressure wall facing said gear side surfaces, said pressure wall having an opening therethrough communicating the interior of said hollow mem ber with said high pressure zone, said last mentioned side wall constituting a rigid, plate-like wear member interposed between said gear side surfaces and said pressure wall and substantially overlapping said gear side surfaces adjacent said pressure zone whereby said high pres-- sure discharge zone is effectively sealed.

7. A gear pump comprising a pump casing providing a'pump cavity having meshing gears rotatable therein and having intake and discharge'passages communicating therewith, said gears in part defining a high pressure discharge zone of said cavity at the meshing teeth thereof, said discharge zone being further defined by a unit pro vided with a sealing surface in yieldable engagement with the peripheries of gear teeth approaching said zone, said unit provided with means for urging said sealing surface into sealing engagement with the peripheries of said gear teeth, and opposed sidewalls in sealing engagement with the sides of said gears, one of said sidewalls including deformable discharge pressure responsive means to urge a side surface of said unit in sealing engagement'with the opposite'side wall whereby said high pressure discharge zone is efiectively sealed.

8. A gear pump comprising a pump-casing providing a pump cavity having meshing gears rotatable therein and having intake and discharge passages communicating therewith, said gears in part defining a high pressure discharge zone of said cavity at the meshing teeth thereof, said discharge zone being further defined by a unit provided with a sealing surface in yieldable engagement with the peripheries of gear teeth approaching said zone, said unit provided with discharge pressure receiving means for urging said sealing surface into sealing engagement with the peripheries of said gear teeth, and opposed side walls in sealing engagement with the sides of said gears, one of said side walls including deformable discharge pressure responsive means to urge a side surface of said unit in sealing engagement with the opposite side wall whereby said high pressure discharge zone is effectively sealed. I

9. A gear pump comprising a pump casing providing a pump'cavity having meshing gears rotatable therein and having intake and discharge passages communicating therewith, said gears in part defining a high pressure discharge zone of said cavity at the meshing teeth thereof, said discharge zone being further'defined by a unit pro-' vided with-a sealing surface in yieldable engagement with the peripheries of gear teeth approaching said zone, said unit provided with discharge pressure receiving means said high pressure discharge zone having associated therewith resilient means for urging said sealing surface into sealing engagement with the peripheries of said gear teeth, and opposed side walls in sealing engagement with the sides of said gears, one of said side walls including deformable discharge pressure responsive means to urge a side surface of said unit in sealing engagement with the opposite side wall whereby said high pressure discharge zone is effectively sealed.

10. A gear pump comprising a pump casing providing a pump cavity having meshing gears rotatable therein and having intake and discharge passages communicating therewith, said gears in part defining a high pressure discharge zone of said cavity at the meshing teeth thereof, said discharge zone being further defined by a unit provided with a sealing surface in yieldable engagement with the peripheries of gear teeth approaching said zone, said unit provided with resilient means urging said sealing surface into sealing engagement with the peripheries of said gear teeth, and opposed side walls in sealing engagement with the sides of said gears, one of said side walls including deformable discharge pressure responsive means to urge a side surface of said unit in sealing engagement with the opposite side wall whereby said high pressure discharge zone is effectively sealed.

11. A gear pump comprising a pump casing providing a pump cavity having meshing gears rotatable therein and :having intake and discharge passages communicating therewith, .said gears in part defining a high pressure discharge zone of said cavity at the meshing teeth thereof, said discharge zone being further defined by a unit provided with 'a sealing surface in yieldable engagement with the'peripheries of gear teeth approaching said zone, said unit provided with resilient means and having limiting means associated therewith for urging said sealing surface into sealing engagement with the peripheries of said gear teeth, and opposed side walls in sealing engagement with the sides of said gears, one of said side walls including deformable discharge pressure responsive means to urge a side surface of said unit in sealing engagement with the opposite side wall whereby said high pressure discharge zone is effectively sealed.

' 12. A gear pump comprising a pump casing providing a pump cavity having meshing gears rotatable therein and having intake and discharge passages communicating therewith, said gears in part defining a high pressure discharge zone of said cavity at the meshing teeth thereof, said discharge zone being further defined by a unit provided with a sealing surface in yieldable engagement with the peripheries of gear teeth approaching said zone, and opposed side walls in sealing engagement with the sides of said gears, one of said side walls including deformable discharge pressure responsive means to urge a side surface of said unitlin sealing engagement with the opposite side wall whereby said high pressure discharge zone is effectively sealed, said side walls adapted to limit the extent of engagement brought about between the sealing surface of said unit and the peripheries of said gear teeth.

13. A gear pump comprising a pump casing providing a pump cavity having meshing gears rotatable therein and having intake and discharge passages communicating therewith,'said gears in part defining a highpressure 'discharge zone of said cavity at the meshing teeth thereof, said discharge zone being further defined by a unit provided with a sealing surface in yieldable engagement with the peripheries of gear teeth approaching said zone, said unit provided with discharge pressure receiving means for urging said sealing surface into sealing engagement with the peripheries of said gear teeth, and opposed side walls in sealing engagement with the sides of said gears, one'of said side walls including deformable discharge pressure responsive means to urge a side surface of said unit in sealing engagement with the opposite side wall whereby saidhigh pressure dischargezone iseffectively sealed, said side walls cooperating with said sealing surface to limit the extent of engagement brought about between said sealing surface and the peripheries of said gear teeth.

14. A gear pump comprising a pump casing providing a pump cavity having meshing gears rotatable therein and having intake and discharge passages communicating therewith, said gears in part defining a high pressure discharge zone of said cavity at the meshing teeth thereof, said discharge zone being further defined by a unit provided with a sealing surface in yieldable engagement with the peripheries of gear teeth approaching said zone, said unit provided with discharge pressure receiving means having associated therewith resilient means for urging said sealing surface into sealing engagement with the periphcries of said gear teeth, and opposed side walls in sealing engagement with the sides of said gears, one of said side walls including deformable discharge pressure responsive means to urge a side surface of said unit in sealing engagement with the opposite side wall whereby said high pressure discharge zone is effectively scaled, said side walls cooperating with said sealing surface to limit the extent of engagement brought about between said sealing surface and the peripheries of said gear teeth.

15. A gear pump comprising a pump casing providing a pump cavity having meshing gears rotatable therein and having intake and discharge passages communicating therewith, said gears in part defining a high pressure discharge zone of said cavity at the meshing teeth thereof, said discharge zone being further defined by an elastomer unit provided with a sealing surface in yieldable engagement with the peripheries of gear teeth approaching said zone, and opposed side walls in sealing engagement with the sides of said gears, one of said side walls including deformable discharge pressure responsive means to urge a side surface-of said unit in sealing engagement with the op posite side wall whereby said high pressure discharge zone is effectively sealed.

16. A gear pump comprising a pump casing providing a pump cavity having meshing gears rotatable therein and having intake and discharge passages communicating therewith, said gears in part defining a high pressure discharge zone of said cavity at the meshing teeth thereof, said discharge zone being further defined by a rigid metallic unit provided with a sealing surface in yieldable engagement with the peripheries of gear teeth approaching said zone, and opposed side walls in sealing engagement with the sides of said gears, one of said side walls including deformable discharge pressure responsive means to urge a side surface of said unit in sealing engagement with the opposite side wall whereby said high pressure discharge zone is effectively sealed.

1?. A gear pump comprising a pump casing providing a pump cavity having meshing gears rotatable therein and having intake and discharge passages communicating therewith, said gears in part defining a high pressure discharge zone of said cavity at the meshing teeth thereof, said discharge zone being further defined by a unit including a pair of arcuate, concave surfaces in yieldable engagement with theperipheries of gear teeth approaching said zone and being in outwardly concentric relation vtothe peripheries of said teeth, and opposed side walls in sealing engagement with the sides of said gears, one of said side walls including deformable discharge pressure responsive means to urge a side surface of said unit in sealing engagement with the opposite side wall whereby said high pressure discharge zone is effectively sealed.

1%. A gear pump comprising a pump casing providing a pump cavity having meshing gears rotatable therein and having intake and discharge passages communicating therewith, said gears in part defining a high pressure discharge zone oflsaid cavity at the meshing teeth thereof, said discharge zone being further defined by a unit comprising a pair of arcuate, concave surfaces in yieldable engagement with the peripheries of .gear teeth approaching said zone and being in outwardly concentric relation to the peripheries of said teeth, the innermostends of said surfaces defined by upwardly projecting lips separated by an indentation, said lips adapted to be flexed into sealing engagement with said gear teeth in response to discharge pressure, and opposed side walls in sealing engagement with the sides of said gears, one of said side walls including deformable discharge pressure responsive means to urge a side surface of said unit in sealing engagement with the opposite side wall whereby said high pressure discharge zone is effectively sealed.

19. A gear pump in accordance with claim 15, in which said unit is of hollow cup-like form and has openings communicating the interior thereof with said discharge pressure zone and discharge passage.

20. A gear pump in accordance with claim 15, in which said unit is of hollow cup-like form and has openings communicating the interior thereof with said discharge pressure zone and'discharge passage, and a rigid external metal sheath mounted on the sealing surface thereof for engagement with said gear teeth.

21. A gear pump comprising a pump casing providing a pump cavity having meshing gears rotatable therein and having intake and discharge passages communicating therewith, said gears in part defining a high pressure discharge zone of said cavity at the meshing teeth thereof, said discharge zone being further defined by a unit including a rigid metallic member provided with an arcuate sealing surface for yieldable sealing engagement with the peripheries of gear teeth approaching said zone, said member having an internally positioned deformable means in communication with said pressure zone to move said member into sealing engagement with said gear teeth in response to discharge pressure, and opposed side walls in sealing engagement with the sidesvof said gears, one of said side walls including deformable discharge pressure responsive means to urge a side surface of said unit in sealing engagement with the opposite side wall whereby said high pressure discharge zone is effectively sealed.

22. A gear pump comprising a pump casing providing a pump cavity having meshing gears rotatable therein and having intake and discharge passages communicating therewith, said gears in part defining a high pressure discharge zone of said cavity at the meshing teeth thereof, said discharge zone being further defined by a unit including a pair of rigid metallic members each positioned to one side of said zone and each provided with an arcuate sealing surface for yieldable sealing engagement with the peripheries of gear teeth approaching said zone, each of said members having an internally positioned deformable means in communication with said pressure zone to move said member into sealing engagement with said gear teeth in response to discharge pressure, and opposed side walls in sealing engagement with the sides of said gears, one of said side walls including deformable discharge face of said unit in sealing engagement with the opposite side wall whereby said high pressure discharge zone is effectively sealed.

23. A gear pump comprising a pump casing providing a pump cavity having meshing gears rotatable therein and having intake and discharge passages communicating therewith, said gears in part defining a high pressure discharge zone of saidcavity at the meshing teeth thereof, said discharge zone being further defined by a unit provided with a pair of arcuate, concave sealing surfaces in yieldable engagement with the peripheries of gear teeth approaching said zone and being in outwardly concentric relation thereto, said unit provided with means for urging said sealing surfaces into sealing engagement, said means including an elastically deformable member pressure responsive means to urge a side sur- 14 behind said unit communicating with said pressure zone, and opposed side walls in sealing engagement with the sides of said gears, one of said side walls including deformable discharge pressure responsive means to urge a side surface of said unit in sealing engagement with the opposite side wall whereby said high pressure discharge zone is effectively sealed, the bottom edges of said side walls resting on said sealing surfaces to limit the extent of engagement brought about between said surfaces and the peripheries of said gear teeth.

24. A gear pump comprising a pump casing providing a pump cavity having meshing gears rotatable therein and having intake and discharge passages communicating therewith, said gears in part defining a high pressure discharge zone of said cavity at the meshing teeth thereof, said discharge zone being further defined by a unit provided with a pair of concave arcuate sealing surfaces adapted to engage the peripheries of gear teeth approaching said zone, a plunger, means for moving said plunger into contact with said unit to move the sealing surfaces thereof into engagement with the peripheries of said gear teeth, resilient means for resisting movement of the sealing surfaces and plunger away from the peripheries of said gear teeth, and opposed side walls in sealing engagement with the sides of said gears, one of said side walls including deformable discharge pressure responsive means to urge a side surface of said unit in sealing engagement with the opposite side wall whereby said high pressure discharge zone is effectively sealed.

25. A gear pump comprising a pump casing providing a pump cavity having meshing gears rotatable therein and having intake and discharge passages communicating therewith, said gears in part defining a high. pressure discharge zone of said cavity at the meshing teeth thereof, said discharge zone being further defined by a unit including a pair of concave arcuate sealing surfaces adapted to engagethe peripheries of gear teeth approaching said zone, a plunger, means for moving said plunger into contact with said unit to move the sealing surfaces thereof into engagement with the peripheries of said gear teeth, resilient means for resisting movement of the sealing surfaces and plunger away from the peripheries of said gear teeth, said means for moving the plunger comprising a sleeve threaded on said plunger and a fixed abutment on the casing against which the sleeve is adapted to bear, said resilient means comprising casing and aspring compressed the second abutment, and opposed side walls in sealing engagement with the sides of saidgears, one of said side walls including deformable discharge pressure responsive means to urge a side surface of said unit in sealing engagement with the opposite side-wall whereby said high pressure discharge zone is effectively sealed.

References Cited in the file of this patent UNITED STATES PATENTS