US3525579A - Gear pump having a mechanically supported movable element - Google Patents

Description

Aug. 25, 1970 J E, CYGNQR 3,525,579

GEAR PUMP HAVING MECHANICALLY SUPPORTED MOVABLE ELEMENT Filed March 5, 1969 2 Sheets-Sheet 1 F iGul FIG-3 6 By RM 40 W firraQ/vm United States Patent O U.S. Cl. 418107 16 Claims ABSTRACT OF THE DISCLOSURE A gear pump having intermeshing gears capable of pumping fluids containing highly abrasive contaminants characterized by a unitary movable element having separate arcuate surfaces, each arcuate surface engaging the periphery of a single gear, symmetrically disposed inclined planes positioned outboard said unitary element, a plurality of wedges positioned intermediate said inclined planes and said unitary movable member with a small angle on the inclined planes such that the wedges produce a nonreversible characteristic and the movable element is maintained in engagement with the periphery of the gears with substantially no load imposed on the gear teeth. A second embodiment in which the angle on the inclined planes is increased to the point where the balance of the forces restraining inboard movement of the wedges is only slightly positive such that a slight increase in the rejection force due to thermal expansion will cause the wedges to move inboard thus preventing a build-up of inwordly directed forces on the movable element.

BACKGROUND OF THE INVENTION Field of the invention This invention pertains to gear pumps of the kind comprising a housing with a pair of meshed toothed gears disposed therein having a unitary movable element adjacent the pump outlet engaging the periphery of each gear such that the gear pump can be utilized to pump a fluid containing highly abrasive contaminants at high output pressures while maintaining exceptionally high volumetric efliciencies.

DESCRIPTION OF THE PRIOR ART The volumetric efliciency of a gear pump depends upon the closeness of the fit between the tips of the gear teeth and the enclosing housing. When a gear pump is utilized to pump a fluid containing a high abrasive contaminant, the clearance between the tips of the gear teeth and the surrounding housing rapidly becomes enlarged and the pump volumetric efliciency falls off.

One well known method of providing a solution to this problem of rapid high wear is to insert a unitary movable element in the pump housing adjacent the pump outlet. This unitary movable element is urged by discharge pressure into engagement with the periphery of the gear teeth adjacent the pump discharge area. U.S. Pat. No. 2,996,- 999 by Trautman is an example of prior art structure wherein a unitary movable element positioned adjacent the pump discharge area is urged by discharge pressure into engagement with the gear teeth. Prior art gear pumps utilize pressure loaded movable elements and contacting gear teeth made of extremely hard wear resistant material, such as tungsten carbide. The peripheral contact of the gear teeth and the mating wiping surfaces of the movable element present an extremely durable surface that can withstand the high abrasive action of the contaminated fluid. It is well known that this conventional COl'lstruction of a gear pump adapted to pump fluids contain- 3,525,579 Patented Aug. 25, 1970 ing highly abrasive contaminants results in a vectored load being transmitted from the movable element through the gears to the gear shaft bearings. The magnitude of the load imposed on the gear shaft bearings by the unbalanced hydraulic pressure impressed on the movable element is somewhat dependent upon the particular gear sideplate design or construction utilized in a particular pump application. However, in the hydraulically loaded movable element form of gear pump, a vectored load is an absolute and cannot be eliminated from this form of gear pump construction. This prior art form of gear pump utilizing a hydraulically actuated movable element maintained in engagement with the periphery of the gear teeth by pump discharge pressure has been suitable for maintaining high volumetric efficiency when pumping con taminated fluids. However, this form of gear pump impresses a vectored load on the gear shaft bearings with a resultant accelerated loss of pumping efliciency due to excessive journal bearing wear causing a reduction in peripheral pump sealing engagement.

SUMMARY OF THE INVENTION The present invention discloses a gear pump that has a unitary movable sealing element containing separate arcuate surfaces each of which engages the periphery of a single gear, with the movable element so constructed that a plurality of wedges are interposed between the movable element and the pump housing to maintain the movable element in continuous peripheral sealing engagement while imposing no load on the periphery of the gear teeth.

The relationship of the cyclic load imposed on the movable element by the intermeshing action of the pump gear teeth can best be described by reference to FIG. 6 wherein a graphic representation of the variable pump discharge pressure impressed on the movable element is shown. On a unitary movable element having two spaced apart wiping surfaces with at least two teeth of each gear in sealing engagement with its respective wiping face at any instant, a minimum total of three teeth of the combined gears must run against the two wiping faces of the movable element. At the precise instant in time when one tooth of one gear contacting a given wiping surface disengages from that wiping surface discharge pressure enters the interstice between that tooth and the next outboard tooth, thereby instantaneously subjecting the wiping surface area between the two teeth to discharge pressure. At this precise instant in time the maximum force tending to separate the movable element from the gear teeth is impressed upon the movable element. This condition is designated as point A on the graph shown in FIG. 6. The number of teeth contacting a given Wiping surface alternates between two and three. The second wiping surface is similarly engaged by the teeth of its mating gear, but is fully out of phase in its contact with the gear teeth in relation to its meshing gear. Hence, as the two gears simultaneously rotate, the magnitude of the wiping surface exposed to discharge pressure decreases until the next tooth reaches the point of disengagement with its mating wiping surface. This condition is shown by the line proceeding from point A to point B on the graph shown in FIG. 6. At the next instant of time, when the next tooth located on the opposite gear disengages from its wiping surface, a new volume of fluid confined between the disengaging tooth and the next outboard tooth is instantaneously transformed from pump inlet pressure to pump discharge pressure, and the surface of the movable element subjected to discharge pressure is instantaneously increased to its maximum value. This transient condition and the instantaneous increase in the force on the movable element is shown by the line 3 on that portion of the graph proceeding from point B to point C. The cyclic load fluctuation on the unitary movable element that is characteristic of the operation of a gear pump is represented on the graph of FIG. 6 by the curve formed by the composite of the line from point A to point B, and the line from point B to point C. The magnitude and frequency of variation of the repetitive load fluctuation represented graphically by the composite curve from point A to B to C is dependent upon the particular gear pump tooth design. The point A is definedas the maximum movable element blow-off force, and the point B is defined as the minimum movable element blow-off force. The geometry of the gear pump utilized by the instant invention subjects each wiping surface of the unitary movable element alternately to a load fluctuation that can cause failure of the unitary movable element within that portion of the element connecting the two wiping surfaces. Structural failure of the unitary element is a particularly acute problem with hard nonsensitive brittle materials, such as tungsten carbide, unless the outer extremities of the movable element are rigidly supported in relation to the pump housing to preclude any flexure within the movable element itself.

The relationship of the unitary movable element and its attendant wedge-shaped support members that permit the movable element to continuously sealingly engage the periphery of the teeth of the intermeshing gears while impressing substantially no force on the periphery of the gear teeth can best be described by reference to FIG. 7, wherein a graphical force loading of the wedge structure is presented. Referring to FIG. 7, the structure to the right of the plane of symmetry shows a portion of the unitary movable element 17 with its attendant wiping surface 56 that engages the periphery of the teeth of gear 7 (not shown). Surface 34 of wedge-like member 20 engages surface 22 of element 17 transverse said plane of symmetry. The opposite surface 54 of Wedge 20 engages inclined surface 24 of pump housing 1, surface 24 being inclined in relation to a plane transverse said plane of symmetry at an angle of inclination designated 13. Load piston 26 is disposed in a bore 28 whose axis is transverse said plane of symmetry. Pump discharge pressure is communicated to bore 28 via passageway 30 to generate a force on piston 26 that is directed away from said plane of symmetry and is transferred to said wedgelike member 20. The structure to the left of the plane of symmetry is a mirror image to that shown on the right. If the forces imposed upon wedge-like member 20 are graphically represented as follows:

F =force imposed on element 20 by the piston 26.

F /2(tan B=F =CjBCtlOII force on the element 20 resulting from movable element load F /Z.

FPZCYCHC load impressed on wiping surface 52 of the movable element 17 by operation of the gear pump.

fl=angle of inclined plane.

=coefiicient of friction.

then viewing FIG. 7 it follows from a summation of the forces impressed on wedge element 20 that:

It can be seen from a review of Equation 1 that with a small angle of inclination ([3), say the frictional forces are so much in excess of the ejection forces that the wedge is effectively locked and the load (F /2) is transmitted from movable element 17 directly through wedge into housing 1.

Conversely, it can be seen from Equation 1 that with a substantial angle of inclination (,3), say 35, the wedge ejection force F will exceed the friction force. Hence, the piston can be sized to produce a piston balance force F that in combination with the frictional restraining force 2( F /2) will be slightly in excess of the ejection 4 force F This condition will fixedly position the wedges, but in the event of an increase in wedge loading force F will increase the ejection force F to a value in excess of the combined constant frictional and piston balance forces, thereby causing the wedges to move down the inclined surface.

Accordingly, it is an object of the present invention to provide an improved gear pump having a unitary movable element adjacent the pump outlet wherein wedgeshaped support elements are positioned intermediate the unitary movable element and inclined surfaces on the pump housing such that the movable element continuously sealingly engages the periphery of the teeth of the mating gears with substantially no force impressed upon the periphery of the gear teeth.

Another object of this invention is to provide a geartype pump having a unitary movable element disposed adjacent the pump discharge area and wedge-like support means positioned intermediate said unitary movable element and canted surfaces located adjacent the pump housing wherein the angle of inclination of the canted surfaces is small such that restraining forces acting on the wedge-like elements are so much in excess of the ejection forces that the wedge-like elements are effectively locked to the pump housing and the unitary movable element.

Another object is to provide a gear pump having a unitary movable element disposed in the pump discharge area with wedge-like elements positioned intermediate the movable element and inclined surfaces of the pump housing wherein the angle of the inclined surfaces is sufficiently large such that an increase in the rejection force due to thermal expansion will cause the wedgelike elements to move toward the plane of symmetry and thus prevent any increase in load on the pump gears.

A still further object of this invention is to provide a gear pump housing a unitary movable element disposed in the pump discharge area with wedge-like elements positioned intermediate the movable element and inclined surfaces of the pump housing wherein the angle of the inclined surfaces is sufficiently large to require the rejection force to be balanced by the pump piston force with a slight positive frictional restraining force fixedly positioning said wedge-like elements such that an increase in the rejection force above the magnitude of said slight positive frictional restraining force will cause said wedgelike elements to move toward the plane of symmetry.

Another object of this invention is to provide a gear pump having a unitary movable element located adjacent the pump discharge with wedge-like elements positioned intermediate the movable element and inclined surfaces adjacent the pump housing, each wedge-like element simultaneously engaging the outer extremity of the movable element and the inclined surface such that the outer extremity of the movable element is prevented from flexing as a result of the cyclic load imposed upon the movable element by pump discharge pressure.

DESCRIPTION OF THE DRAWINGS The following is a brief description of the drawings accompanying the detailed description of the instant invention.

FIG. 1 is a front view of one form of pump incorporating the instant invention.

FIG. 2 is a longitudinal sectional view along line 22.

FIG. 3 is a sectional view along line 33.

FIG. 4 is a cross-sectional view along line 4-4.

FIG. 5 is a detailed cross-sectional view in accord with this invention showing a first alternate form of support means.

FIG. 6 is a graphical representation showing the fluctuating separating force imposed on the movable element.

FIG. 7 is a graphical representation showing the distribution of the forces imposed on the wedge support means.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawings, in the following description, like parts are designated throughout by like numerals for all forms shown.

Referring to the example shown in FIGS. 1, 2, 3 and 4, there is provided a pump having a housing 1 defining therein a cavity 2 and a pair of end plates 3 and 4 positioned on opposite sides of housing 1 and secured in fluid tight relation to said housing by a plurality of bolts 5. Rotatably mounted about axes of rotation 11 and 12 in cavity 2 of housing 1 are a pair of intermeshing gears 6 and 7 engaging one another at an area of intermesh indicated generally at 8. Shaft 9 drives gear 6 through a key (not shown). Shaft 10 is keyed to driven gear 7 such that shaft 10 and gear 7 rotate in unison responsive to rotative movement of driver gear 6. Shafts 9 and 10 are journaled in bearings 13, 14, and 16 respectively with a close running fit such that axes of rotation 11 and 12 are maintained substantially parallel. Gears 6 and 7 are disposed in cavity 2 such that an inlet 19 is formed on one side of the intermesh 8 and an outlet 18 is formed on the opposite side of the intermesh 8 so that the rotary fluid displacement means comprising the intermeshing gears 6 and 7 will operate to move the fluid medium acted upon by the pump from the inlet 19 to the outlet 18. As is clearly indicated in FIGS. 2 and 4, the outer diameter of the gears 6 and 7 at the tips or periphery of the gear teeth are disposed in relation to the peripheral wall of cavity 2 adjacent the pump inlet such that there is a pronounced clearance between the periphery of each of the gear teeth and the adjacent cavity wall. This clearance is provided to reduce the possibility of cavitation at the pump inlet when the pump is operated at high speed. The movable peripheral sealing means take the form of movable member 17 positioned adjacent outlet 18 and peripherally sealingly engage gears 6 and 7 respectively.

In this particular embodiment, unitary movable element 17 has first and second parallel surfaces 22 and 23 respectively, said parallel surfaces positioned transverse the plane of symmetry.

Housing 1 has a pair of inclined planes 24 and 25 respectively positioned outboard of unitary movable element 17. Inclined planes 24 and 25 are positioned at equal angles on opposite sides of the plane of symmetry. The inclined plane angle, designated 3, can be varied in accordance with the particular structure dependent upon the force balance design chosen for the particular model pump, as will be explained in detail hereinafter. Slideably movable wedge-shaped members and 21 are positioned intermediate inclined planes and mating parallel surfaces 24, 22, and 23 respectively. A cylindrical bore 28 is positioned in unitary movable element 17 with its axis transverse the plane of symmetry. Pressure balance pistons 26 and 27 are axially slideably disposed in bore 28. Discharge pressure is communicated from chamber 18 into bore 28 via passageway 30 to provide a fluid pressure responsive force F that is a supplemental force to that provided by spring 29. Both forces are transmitted via pistons 26 and 27 to wedge-shaped support members 20 and 21 respectively. Spring 29 positioned intermediate pistons 26 and 27 urges pistons 26 and 27 into engagement with wedge-shaped support elements 20 and 21 respectively to thereby provide the initial fluid sealing contact between the arcuate wiping surfaces of movable element 17 and the mating surfaces of the periphery of gears 6 and 7. Said spring force is transmitted through wedge-shaped elements 20 and 21 to the mating parallel surfaces 22 and 23 of movable element 17 to provide vectored forces to element 17 to maintain contact between the arcuate surfaces 53 and 56 of element 17 and the periphery of gears 6 and 7 respectively during pump startup. Once pumping operation is started and pump discharge pressure is communicated to chamber 28, the re sulting fluid pressure responsive forces on pistons 26 and 27 supplement that provided by spring 29 to provide a combined fluid pressure responsive and spring force that is transmitted through wedge-shaped support elements 20 and 21 during normal pumping operation.

Side members 35 and 36 are positioned intermediate the lateral faces 37 and 144 of gear 6, the lateral faces 38 and 143 of gear 7, and the side surfaces 39 and 40 of end plates 3 and 4 respectively. Seal 41 is located in recess 42 of end plate 3 to form cavity 43. Seal 44 is positioned in recess 45 intermediate sideplate 35 and end plate 3 to form cavity 46. Similarly, seals 47 and 48 are positioned intermediate end plate 4 and sideplate 36 to form chambers 49 and 50. Fluid at discharge pressure is directed through passageways 51 and 52 into chambers 43 and 49 respectively, and thence via interconnecting passageway (not shown) to chambers 46 and 50. Sideplates 35 and 36 responsive to discharge pressure contained in chambers 43, 46, 49 and 50 are urged into sealing engagement with the lateral faces of gears 6 and 7 and the end faces of elements 19 and 20 to form a discharge pocket for outlet 18 bounded by the intermesh 8 of the teeth of the two gears, peripheral sealing contact areas 26 and 27 comprising the periphery of the teeth of gear 6 and the wiping surface 53 of element 20, and the periphery of the teeth of gear 7 and the wiping surface 56 of element 20. It has been found that the peripheral sealing between the periphery of the gear teeth and the mating arcuate surfaces of the movable elements 19 and 20 is the critical leakage path with respect to the operation of a gear pump when pumping a fluid medium containing highly abrasive contaminants. This critical peripheral sealing engagement is represented by areas 26 and 27 of FIG. 4. Accordingly, it is to be understood that the embodiment shown utilizing the two sideplates 35 and 36 is representative of but one form of providing the fluid sealing discharge pocket 18. It has been found that any .form of pressure loaded sideplate that will urge the lateral surfaces of the gears and the lateral surfaces of the movable element into fluid sealing engagement so as to form the fluidly sealed discharge pocket 18 will perform satisfactorily when pumping highly abrasive contaminant fluids. Accordingly, sideplate mechanisms having surfaces in contact with of the lateral surfaces of the pump gears, as exemplified by Roth, Pat. No. 2,420,622; intermediate housing pressure loading, as exemplified by Gordon, Pat. No. 3,292,550; selective sideplate loading, as exemplified by Banker, Pat. No. 2,742,862; or free floating sideplates, as exemplified by Trautman, Pat. No. 2,996,999, may all be used with equally satisfactory results so long as the sideplate or plates urge the lateral surfaces of the gears and the lateral surfaces of the movable element into sealing engagement with the sideplates or the mating surfaces of the end plates such that a fluidly sealable discharge pocket 18 is formed.

It should be noted that in the design of the instant pump as shown in FIG. 4, the seal plates are constructed to terminate at a position inboard of the wedge-shaped elements 20 and 21. This arrangement prevents the seal plates from engaging the side or lateral surfaces of wedgeshaped elements 20' and 21 to thereby preclude the generation of frictional forces that are diflicult to evaluate and control.

Referring to FIG. 4, during initial start-up operation, the initial load of spring 29 maintains contact between the gear teeth tip and movable element 17. This initial sealing contact permits the pumping operation to start. The resultant discharge pressure is communicated to chamber 28 to generate a pressure balance force on pistons 26 and 27 that is communicated to wedge-shaped elements 20 and 21. Simultaneously, pump discharge pressure generates a force which tends to move element 17 away from sealing engagement with the periphery of the tips of gear teeth 6 and 7. This separating force F is resisted by the action of the wedge elements and the inclined planes. In the instant embodiment shown in FIG. 4,

the balanced pistons 26 and 27 are sized such that the combined force produced by spring 29 and the discharge pressure in chamber 28 is of a very nominal magnitude. The angle of the inclined plane B is selected to be a very shallow angle such that the tangent of the angle [3 is less than the coefficient friction ,u. between the wedges and their mating surfaces on the inclined planes and movable element 17. This structure produces a non-reversing mechanical system that will maintain the movable element 17 in sealing engagement with the periphery of the gear teeth of gears 6 and 7 with no net load transmitted through movable element 17 to the periphery of gears 6 and 7.

By way of example, assuming a coefiicient of friction (a) of .4, an angle of inclination (B) of degrees, and substituting these values into Equation 1 described heretofor'e, it can be seen that the net wedge restraining force (F is equal to 9 times the ejection force (F Hence, a pair of wedges having a low angle of inclination produces a non-reversing mechanical system in which the wedges are effectively locked to the inclined surfaces by the greatly excessive frictional restraining forces.

It has been found in certain applications that in the utilization of inclined planes having a low angle of inclination wedge system, the inability of the wedge to be moved can result in superimposed loads induced by thermal expansion being transmitted through movable element 17 to the pump gears 6 and 7, and hence to the pump gear journal bearings. To preclude the generation of these thermal expansion induced loads, it is possible to increase the angle ,8 of the inclined planes to the point where the ejection force (F will be greater than the friction force. In this condition, absent a piston force (F counteracting the ejection force (F the wedge would be moved down the inclined plane towards the plane of symmetry resulting in an increased clearance between the gears and movable element 17.

It has been found that the value of the angle of the inclined plane {3 can be increased to a value where inboard movement of the Wedge-shaped elements 20 and 21 will occur. The resultant ejection force (F represented by the minimum blow-off force, designated as point B in FIG. 6, can be reacted by an equal but opposite piston balance force (P and the remaining friction force is such that it will provide a restraining force that will counteract the movable element 17 discharge pressure load fluctuations from the minimum to the maximum blow-01f load (point B to point C of the curve in FIG. 6) with a small restraining force net balance. Thus, it can be seen that a slight increase in wedge ejection force due to thermal expansion will override the small positive restraining force and will cause the wedge to move down the inclined plane toward the plane of symmetry and thus relieve any thermally induced load that would otherwise be transmitted through element 17 into the periphery of gears 6 and 7.

Referring to FIG. 6, in prior art type of gear pumps incorporating a movable element utilizing discharge pressure to urge the element into sealing engagement with the gears, it was necessary to size the differential pressure urging the movable element into engagement to produce a force level that was approximately two-thirds of the peak cyclic variation, point B to point C, as shown in FIG. 6. The remaining one-third was compensated by the sideplate friction restraining forces generated between the sideplate and the movable element.

In the instant invention, as described above, the balanced piston force is sized to react that portion of the total force reached by the minimum blow-off force (point B of the curve shown in FIG. 6). The total cyclic variation is compensated by means of the wedge frictional force and the sideplate to wedge frictional force such that a small positive restraining force balance exists. It can be seen that the structure of the instant invention eliminates the force represented by the two-third peak cyclic variation that is transmitted through the movable element tothe periphery of the gears in the prior art structure. By way of example, on comparable pumping units, the minimum blow-01f force (point B) is 362 lbs., and the maximum blow-01f force (point C) is 602 lbs. Hence, a force of approximately lbs. directed to the pump journal bearings is eliminated by the structure of the instant invention.

FIG. 5 shows an alternate embodiment wherein cylindrical rollers 32 and 33 replace wedge-shaped elements 20 and 21 respectively. Otherwise, this embodiment operates in the same manner as described in detail above for the structure of FIG. 4.

While a preferred embodiment has been shown and described, various modifications and substitutions may be made without departing from the spirit and scope of this invention. Accordingly, it is to be understood that this invention has been described by way of illustration rather than limitation.

What I claim is:

1. A gear pump having a housing enclosing a chamber:

Intermeshing gears supported on parallel axes of rotation deposed in said chamber;

A plane of symmetry located intermediate an equidistance said axis of rotation and positioned transverse a plane containing said axes of rotation;

Movable peripheral sealing means for said gears;

At least one pressure loaded sideplate urged into en: gagement with the lateral faces of said gears and said peripheral sealing means to sealingly divide said chamber into a high pressure portion and a low pressure portion;

Said chamber having first and second surfaces symmetrically canted with respect to said plane of symmetry;

Support means positioned intermediate said canted surfaces and said peripheral sealing means;

Means continuously urging said support means into simultaneous engagement with said canted surfaces and said movable peripheral sealing means, such that said movable peripheral sealing means continuously sealingly engages the periphery of the teeth of said intermeshing gears with substantially no force impressed on the periphery of said gear teeth.

2. A gear pump, as described in claim 1, wherein said first and said second canted surfaces are symmetrically disposed at a small angle with respect to a plane transverse said plane of symmetry such that the engagement of said support means with said corresponding engaging surfaces generates friction restraining forces on said support means that substantially exceed the forces urging said support means toward said plane of symmetry.

3. A gear pump, as described in claim 2, wherein:

Resilient means biasing said support means such that said movable peripheral sealing means is continuously urged into sealing engagement with the periphery of the teeth of said gears.

4. A gear pump, as described in claim 3, including:

Support means comprising a plurality of independently movable integral support members wherein,

Each intergral support member engages a different one of said canted surfaces and concurrently engages a corresponding surface of said movable peripheral sealing means.

5. A gear pump, as described in claim 1, including:

Force producing means for producing a force responsive to pump pressure urging elements of said support means in a direction away from said plane of symmetry.

6. A gear pump, as described in claim 5, wherein said first and said second canted surfaces are symmetrically disposed at a large angle with respect to a plane transverse said plane of symmetry such that the engagement of said support means with said corresponding engaging surfaces generates friction restraining forces on said support means that are exceeded by the forces urging said support means toward said plane of symmetry and when combined with said pump pressure generated outward directed forces received by said support means, slightly exceed the forces urging said support means toward said plane of symmetry.

7. A gear pump, as described in claim 1, including:

Support means comprising first and second wedgeshaped members;

Pump discharge pressure communicated to said movable peripheral sealing means to simultaneously produce pulsating forces urging said sealing means away from the periphery of the teeth of said gears and said support means toward said plane of symmetry;

Said loading means responsive to pump discharge pressure generating a plurality of forces that are impressed on said first and said second wedge-shaped members to urge said members away from said plane of symmetry;

Said movable peripheral sealing means having first and second parallel surfaces substantially transverse said plane of symmetry;

Said first and said second wedge-shapedmembers engaging said mating first and second canted surfaces and said first and said second peripheral sealing means surfacesrespectively to produce friction restraining forces that exceed the forces urging said wedge-shaped members toward said plane of symmetry to thereby react said pulsating forces such that the peripheral sealing engagement between said peripheral sealing means and said gear teeth is preserved.

8. A gear pump, as described in claim 7, including: cavity located in said movable peripheral sealing means receiving a plurality of axially slideable members to form a chamber therebetween;

Said chamber positioned intermediate said first and second wedge-shaped members and receiving discharge pressure to thereby generate a plurality of axially opposed forces urging said first and second wedge-shaped elements away from 'said plane of symmetry.

9. A gear pump, as described in claim 1, including:

Support means comprising first and second wedgeshaped members;

Pump discharge pressure communicated to said movable peripheral sealing means to simultaneously produce pulsating forces urging said sealing means away from the periphery of the teeth of said gears and said support means toward said plane of symmetry;

Said loading means responsive to pump discharge pressure generating a plurality of forces that are impressed on said first and said second wedge-shaped members to urge said members away from said plane of symmetry;

Said movable peripheral sealing means having first and second parallel surfaces substantially transverse said plane of symmetry;

Said first and said second wedge-shaped members engaging said mating first and second canted surfaces and said first and second peripheral sealing means surfaces respectively to produce friction restraining forces that singularly are less than the forces urging said wedge-shaped members toward said plane of symmetry, but in combination with said forces produced by said load producing means slightly exceed said forces directed toward said plane of symmetry such that upon the super position of a thermally induced increase in said forces directed toward said plane of symmetry, said wedge-shaped members will be urged toward said plane of symmetry to thereby react said pulsating force such that the peripheral sealing engagement between said peripheral sealing means and said gear teeth is preserved with substantially no load impressed on the periphery of said gear teeth.

10. A gear pump, as described in claim 9, including:

A cavity located in said movable peripheral sealing means receiving a plurality of axially slideable members to form a chamber therebetween;

Said chamber positioned intermediate said first and second wedge-shaped members and receiving discharge pressure to thereby generate a plurality of axially opposed forces urging said first and said second wedge-shaped elements away from said plane of symmetry.

11. A gear pump comprising a housing having a bore positioned therein:

A pair of intermeshing gears disposed in said bore;

An inlet on one side of said intermesh and an outlet on the opposite side of said intermesh;

Movable peripheral sealing means positioned adjacent said outlet and sealingly engaging the periphery of the teeth of said intermeshing gears adjacent said outlet;

At least one pressure loaded sideplate urged into engagement with the lateral surfaces of said gears and said movable peripheral sealing means to sealingly enclose a high pressure discharge chamber;

First and second intersecting symmetrical inclined surfaces disposed in said bore adjacent said discharge chamber, said second inclined surfaces being the mirror-image of said first inclined surfaces;

Support means positioned intermediate said inclined surfaces and said movable peripheral sealing means;

Loading means continuously urging said support means into simultaneous engagement with said inclined surfaces and said movable peripheral sealing means such that said peripheral sealing means continuously sealingly engages the periphery of the teeth of said gears adjacent said outlet with substantially no force being applied to the periphery of said gear teeth.

12. A gear pump, as described in claim 11, including:

Support means comprising first and second wedgeshaped members.

13. A gear pump, as described in claim 12, wherein:

Said movable peripheral sealing. means comprises a unitary member constructed to engage the periphery of the teeth of said gears adjacent said outlet while simultaneously occupying substantially all of the volume of said high pressure discharge chamber;

Said unitary member further including first and second parallel surfaces positioned opposite said area of sealing engagement with the periphery of said gear teeth.

14. A gear pump, as described in claim 13, including:

A first discharge pressure generated pulsating separating force urging said unitary sealing member away from the periphery of said gear teeth;

A second discharge pressure generated pulsating force urging said first and second wedge-shaped members inward towards said intermesh;

Discharge pressure generated outward directed loading means forces impressed on said first and said second wedge-shaped members in opposition to said inward directed pulsating forces;

Said first and said second inclined planes positioned at equal small angles in relation to said first and said second parallel surfaces respectively, such that said first and said second wedge-shaped members engage said first parallel surface and said first inclined plane, and said second parallel surface and said second inclined plane respectively to produce friction restraining forces that greatly exceed said inward directed pulsating forces while simultaneously transmitting said pulsating separating force from said unitary sealing member to said inclined planes such that said unitary sealing member and the periphery of said gear teeth are maintained in sealing engagement with substantially no force impressed on the periphery of said gear teeth.

15. A gear pump, as described in claim 13, including:

A first discharge pressure generated pulsating separating 1 1 1 2 force urging said unitary sealing member away from taneously said pulsating separating force is transthe periphery of said gear teeth; mitted from said unitary sealing member to said in- A second discharge pressure generated pulsating force clined planes, via said first and said second wedgeurging said first and said second wedge-shaped memshaped members. bers inward towards said intermesh; 5 16. A gear pump, as described in claim 11, including:'

Loading means including discharge pressure generated Support means comprising first and second cylindricaloutward directed forces impressed on said first and shaped members. said second wedge-shaped members in opposition to said inward directed pulsating forces; References fll Said first and said second inclined planes positioned UNITED TS at equal large angles in relation to said first and said v r 1 second parallel surfaces such that said first and said second wedge-shaped members engage said first paral- 2,742,862 4/1956 Banker lel surface and said first inclined plane, and said sec- 0nd parallel surface and said second inclined plane v $52 2 respectively to produce friction restraining forces 2996999 8/1961 T elgte I smaller than said inward directed pulsating forces, 312301l 3/1964 but combined with said outward directed forces to 3208393 9/1965 g produce resultant forces slightly greater than said 3427985 2/1969 a inward directed pulsating forces, whereby thermally 3429270 2/1969 N 1 induced secondary forces superimposed on said first 06 e a and second wedge-shaped support members will cause DONLEY I STOCKING Primary Examiner said wedge-shaped support members to move inward such that said unitary sealing means and the periphery D Assistant Exammel' of said gear teeth are maintained in continuous seal- U S Cl X R ing engagement with substantially no force transmitted to the periphery of said gear teeth, while simul- 103-216; 418133, 157

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