US3292551A

US3292551A - Gear pump or motor

Info

Publication number: US3292551A
Application number: US450989A
Authority: US
Inventors: Richard O Gordon
Original assignee: Clark Equipment Co
Current assignee: Doosan Bobcat North America Inc
Priority date: 1965-04-26
Filing date: 1965-04-26
Publication date: 1966-12-20
Anticipated expiration: 1983-12-20

Description

Dec. 20, 1966 R. o. GORDON GEAR PUMP OR MOTOR SSheets-Sheet 1 Filed April 26, 1965 I NVENTOR RICHARD O. GORDON ATTORNEY R- O. GORDON GEAR PUMP 0R MOTOR Dec. 20, 1966 5 Sheets-Sheet 2 Filed April 26, 1965 RICHARD O. GORDON I0 I BY ATTORNEY Dec. 20, 1966 R. o. GORDON GEAR PUMP OR MOTOR 5 Sheets$heet 5 Filed April 26. 1965 INVENTOR RICHARD o. GORDON (UM ATTORNEY United States Patent Filed Apr. 26, 1965, Ser. No. 450,989 2 Claims. (Cl. 103-126) This invention relates to fluid displacement pumps and motors, and more particularly to improvements in pressure loaded gear pumps and motors.

Numerous problems have been encountered in the art of pressure loaded gear pumps and motors, particularly those designed for generating relatively high discharge pressures, operable at high mechanical and volumetric efficiencies, and capable of high performance operation for relatively long periods of time with minimum maintenance requirements, concerning which many and varied solutions have been previously proposed. A discussion of the prior art and the nature of such problems which have been encountered heretofore are reviewed in my Patent No. 3,137,238, granted June 16, 1964.

The present invention is concerned with improvements in the structure of such gear pumps and motors to provide a unit in which the sealing force applied inwardly at selected areas on the outer surfaces of the thrust plate sealing members is controlled to exceed the internal force exerted outwardly at corresponding areas on the inner faces of the sealing members by substantially the same predetermined differential, thus providing a positive sealing force which is substantially the same throughout the area of the side surface of the adjacent gears. Briefly, this is accomplished by providing a plurality of movable wall or piston members of preselected area and location which respond to the fluid pressures existent in different circumferentially spaced gear pocket areas for imposing on the outer surfaces of the thrust plate sealing members a force which is always proportional to the pressure in the gear pocket area to which the respective piston member responds.

It is therefore an object of the invention to provide an improved gear pump or motor construction in which accurate pressure gradient compensation is realized by the use of control area variants which provide for a wide range of flexibility in design.

It is an additional object to provide an improved pump or motor construction utilizing localized internal gear pocket pressures to provide the sealing forces in corresponding localized areas on the outer surface of the sealing member.

Another object of the invention is to provide a generally improved gear pump or motor construction.

Other objects, advantages, and features of the present invention will become apparent from the following detailed description thereof taken in conjunction with the drawings wherein:

FIGURE 1 is a longitudinal sectional view of a pressure loaded, intermeshing gear pump taken along the line 11 of FIG. 2 in accordance with one embodiment of the present invention;

FIGURE 2 is an elevational end view of the pump taken from the right-hand side of FIG. 1 with the cover plate removed;

FIGURE 3 is an elevational end view of a modified form of the cover plate shown in FIGS 1 and 2;

FIGURE 4 is a partial sectional view of a modification of the construction shown in FIG. 1; and

FIGURE 5 is an elevational end view of another modified form of the cover plate.

Referring now in detail to FIG. 1 and 2, numeral denotes a suitably chambered gear pump housing in which are rotatably mounted a driven gear 12 and an 3,292,551 Patented Dec. 20, 1966 ice intermeshing driving gear 14. Driven gear 12 is supported on a shaft 16 journaled on its right side in a roller bearing 18 and on its left side in a roller bearing 20; driving gear 14 has a splined shaft 22 journaled on its right side in a roller bearing 24 and intermediate its ends in a roller bearing 26. The

roller bearings

18, 20, 24 and 26 are mounted in annular recesses in

thrust plate bushings

28, 30, 32 and 34, respectively, the vertically related pairs of which bushing have flat mating surfaces at

numerals

36 and 38, respectively. Generally figure-8

shaped wear plates

40 and 42 are interposed between the respective pairsof thrust plate bushings and the opposite side'faces of the

gears

12 and 14. All of the aforesaid parts of the pump structure are mounted within the figure-8 shaped gear chamber 44 formed by body housing 10. An opening 46 is formed in each thrust plate bushing and wear plate of somewhat larger diameter than the driving or driven shaft which passes therethrough to avoid wear and to facilitate drainage of any leakage fluid from the gear chamber through the various bearings and back to the inlet of the pump as will be described below.

Front and rear

cover plate housings

50 and 52 are formed to mate with corresponding end surfaces of the body housing 10 and the various thrust plate bushings, as shown, and a plurality of studs 54 extend through openings 56 in body housing 10 and threadedly engage cover housing 50. Recessed

chambers

58 and 60 are formed in cover plate 52 adjacent the ends of the shaft members and are connected by a passage 62 for venting leakage fluid which passes

bearings

18 and 24 to the inlet of the pump by way of a passage 62 in shaft 16, a chamber 64 formed in cover housing 50, a passage 66 in the cover housing, and a passage 68 which may be connected to the inlet conduit 70 of the pump, while leakage fluid which passes bearing 26 flows along the shaft 22 and is vented to the inlet conduit by way of

passages

66 and 68.

Shaft sealing means 72 is located in an enlarged chamber 74 of cover housing 50 between a seal retainer member 76, the shaft 22, and a portion of the cover housing. A snap ring 78 locates seal retainer 76 in chamber 74. The pump body and cover housing portions are pressure fluid sealed in operation by means of O-

rings

80 and 82 which are located in the body housing circumferentially outwardly of gear chamber 44. A discharge conduit 84 is located in the body housing and opens into gear chamber 44 at the discharge side of the gears.

A plurality of axially extending passages extend inwardly of the body and rear cover housings from the mating surfaces 92 of said housings, and are vented at their one ends to preselected portions of the gear chamber adjacent the pockets of the gears and at their other ends to a plurality of chambers 94 which are formed in cover plate 52 in symmetrical relation to the gear chamber opening formed in body housing 10, as best shown in FIG. 2. A piston element 96 is located in each chamber 94 and responds to pressure fluid vented to the respective chambers from the localized areas in the gear chamber to which the passages 90 are connected. An O-ring 98 is located in cover plate 52 in circumferential relation to each passage 90 in order to prevent leakage through the mating housing surfaces 92. The inner ends of piston elements 96 abut with the outer end of

thrust plate bushings

28 and 32 and impose a force thereon which acts through the various thrust plate bushings and wear

plates

40 and 42 to seal the side faces of the gears with a force which is always proportional to the fluid pressure existent in the axially opposed localized area of the gear chamber 44. Inasmuch as the pressure in different localized areas of the gear chamber may vary widely during operation as a function of operating parameters such as pump r.p.m., fluid viscosity, cavitation, the volume of air entrained in the fluid being pumped, and others, it will be apparent to persons skilled in the art that to the extent that piston elements 96 of predetermined area are properly located in relation to the outer end of the

thrust plate bushings

28 and 32 and are properly vented to diflFerent localized areas in the gear chamber, the sealing force imposed on the thrust plate bushings and wear plates by the plurality of piston elements will always vary in accordance with the particular. pressure gradient condition existing in the gear chamber of the pump irrespective of variations in those factors which affect the pressure gradient, all as discussed in detail in my aforementioned patent.

In the present embodiment, for example, it will be noted (see FIG. 2) that the passage 90 which is located in inlet conduit 70 suppliesinlet pressure fluid to. the three chambers 94 which are adjacent the inlet conduit, whereas the passage 90 which is located adjacent the discharge conduit 84 provides discharge pressure fluid to three chambers 94 which are located adjacent the discharge conduit, and each of the other three passages 90 located peripherally of the upper and lower gear chambers provide pressure fluid from adjacent each respective area of the gear chamber to one or more chambers 94. It should be understood that inlet pressure fluid is vented to those portions of the ends of

bushings

28 and 32 not in abutment with the piston elements 96; i.e., the area of the bushing ends surrounding the various piston elements.

Referring now to FIG. 3, the pump structure may be the same as described with reference to FIGS. 1 and 2, except that the distribution of piston chambers and elements in the cover plate 52 is modified to provide the configuration shown in the cover plate 100. Openings 52 for receiving studs 54 are the same as in FIGS. 1 and 2. Three piston chambers 102 are located adjacent the dis charge portion of the gear chamber and are vented by way of passages 104 to the pressure fluid in the discharge conduit in a manner similar to that shown in FIG. 2. Upper and lower piston chambers 106 are located near the upper and lower portions of the gear chamber and are vented to the axially adjacent fluid pressures in the chamber by way of passages 108, whereas chambers 110 are located somewhat towards the inlet side of the pump from the vertical axis thereof and are vented to the axially adjacent portions of the gear chamber by passages 112. The remaining area of the cover plate 100 disposed axially adjacent the gear chamber which is not abutted by the piston elements 96, which are, of course, adapted to be located in the various piston chambers shown in FIG. 3, is vented to pump inlet pressure. Thus, by somewhat less complex and lower cost pump structure than that of FIGS. 1 and 2, an approximation of that force required to properly seal the side faces of the gears by way of the various thrust plate bushings and wear plates is achieved under varying conditions of pressure gradient in the gear chamber. It will be observed that the entire portions of the

bushings

28 and 32 which lie axially adjacent the inlet'side of the pump are subjected to inlet pressure, but that the previous requiremnt in the prior art for masking off the said area of the thrust plate by means such as is disclosed in my above-mentioned patent in order to prevent excessive differential pressures acting adjacent the inlet side of the pump to seal the gear side faces, has been eliminated.

In FIG. 4 I disclose in partial view a modification of the structure shown in FIG. 1 in which similar parts are similarly numbered, the only significant difference being a simplification of the structure of the passage means for venting the gear chamber to the piston chambers by providing a straight drilled, axially extending passage 116 which extends through the piston element 118, which is preloaded by a spring 120 and has an O-ring 122 located in the piston element surrounding the passage 116 to prevent leakage through the mating surfaces 92 of the

housing portions

10 and 52. The location of the piston elements 118 may be in accordance with the embodiments shown in either FIGS. 2 or 3, or as shown in FIG. 5, to be described.

Referring to FIG. 5, the cover plate 130 is substantially the same as the. cover plate 52- described in conjunction with FIGS. 1 and 2, including the distribution of piston chambers 94. However, in FIG. 5 the passage construction 116, as described with regard to FIG. 4, is utilized for facilitating maximum accuracy in the response of the piston elements operable in chambers 94 in respect of possible variations in pressure as between the, nine different gear vented chambers 94 in both the upper and lower gear chamber portions. That is, each of the chambers 94 in FIG. 5 is individually vented by means of a straight drilled passage 116 which connects a different portion of the gear chamber in each instance to the respective piston chamber. Consequently, the most accurate compensation for variations in pressure gradient under varying condition of pump operation may be obtained in the use of the FIG. 5 embodiment, wherein every circumferential portion of each of the upper and lower gear chambers is vented individually to the adjacent compensating piston chamber, so that collectively the piston elements exert a total gradient compensated thrust of the thrust plate bushings and wear plates which varies at all times in direct proportion to the fluid pressure existing in each of the axially adjacent gear chamber areas.

O-rings 98 in FIG. 3 correspond to the similarly numbered O-rings in FIG. 1, and O-rings 122 in FIG; 5 correspond to the similarly numbered O-ring in FIG. 4. In the embodiments of FIGS. 1, 2 and 5 it will be noted that the symmetry of distribution of the piston elements facilitates a ready solution to the problem of providing a reversible pump by the use of check valves to reverse the inlet and discharge conduit connections, as may be required in operation.

From the foregoing, it is believed that those familiar with the art will readily recognize and appreciatethe novel concepts and features of the present invention. Also, while the invention has been described in relation to only a few embodiments, variations, changes and substitutions of equivalents will present themselves to persons skilled in the art, and may be made without necessarily departing from the scope and principles vof the invention. It will be appreciated that although the invention has been described herein with particular emphasis on its application to intermeshing gear type pumps,-

the principles of the invention are as readily applicable to intermeshing gear type motors. As a result, it is not my intention to be limited to any particular form of the invention herein illustrated and described except as may appear in the claims appended.

I claim:

1. In a gear pump or motor, a gear body housing containing a pair of intermeshing gears, axially movable thrust plate means mounted on at least one side of the gears and having a remote abutment surface and a sealing surface for sealing the adjacent side faces of the gears, an inlet leading to and outlet leading from said body housing, a cover housing secured to said body housing at one end thereof, a plurality of piston chambers in the .cover housing located in predetermined spaced relation, a plurality of corresponding piston elements in said chains hers movable axially of the pump into abutment with said remote surface of the thrust plate means, the parting planar surface between said cover and body housings being substantially coincident with the one ends of said piston chambers, passage means connecting the other ends of said piston chambers to a plurality of peripheral gear chamber areas which include gear chamber areas intermediate the inlet and discharge conduits, said passage means extending directly through the thrust plate means and throug each piston element in the cover housing to vent the said other ends of the piston chambers to the respective gear areas, said plurality of piston elements being adapted to act in concert to impose upon the thrust plate means variably axially directed forces for sealing the adjacent side faces of the gears as a function of variations in fluid pressure existent between the plurality of connections of the piston chambers to the gear chambers, the area of said remote surf-ace of said thrust plate means which is not engaged by said piston elements being vented to a gear chamber pressure less than discharge pressure.

2. A pump or motor as claimed in claim 1 wherein sealing means surrounds each of said passage means at the connection thereof at the mating surfaces of said body and cover housings.

References Cited by the Examiner UNITED STATES PATENTS FOREIGN PATENTS 3/1957 Great Britain.

DONLEY J. STOCKING, Primary Examiner.

WI'LBUR I. GOODLIN, Examiner.

Claims

1. IN A GEAR PUMP OR MOTOR, A GEAR BODY HOUSING CONTAINING A PAIR OF INTERMESHING GEARS, AXIALLY MOVABLE THRUST PLATE MEANS MOUNTED ON AT LEAST ONE SIDE OF THE GEARS AND HAVING A REMOTE ABUTMENT SURFACE AND A SEALING SURFACE FOR SEALING THE ADJACENT SIDE FACES OF THE GEARS AN INLET LEADING TO AND OUTLET LEADING FROM SAID BODY HOUSING, A COVER HOUSING SECURED TO SAID BODY HOUSING AT ONE END THEREOF, A PLURALITY OF PISTON CHAMBERS IN THE COVER HOUSING LOCATED IN PREDETERMINED SPACED RELATION, A PLURALITY OF CORRESPONDING PISTON ELEMENTS IN SAID CHAMBERS MOVABLE AXIALLY OF THE PUMP INTO ABUTMENT WITH SAID REMOTE SURFACE OF THE THRUST PLATE MEANS, THE PARTING PLANAR SURFACE BETWEEN SAID COVER AND BODY HOUSINGS BEING SUBSTANTIALLY COINCIDENT WITH THE ONE ENDS OF SAID PISTON CHAMBERS, PASSAGE MEANS CONNECTING THE OTHER ENDS OF SAID PISTON CHAMBERS TO A PLURALITY OF PERIPHERAL GEAR CHAMBER AREAS WHICH INCLUDE GEAR CHAMBER AREAS INTERMEDIATE THE INLET AND DISCHARGE CONDUITS, SAID PASSAGE MEANS EXTENDING DIRECTLY THROUGH THE THRUST PLATE MEANS AND THROUGH EACH PISTON ELEMENT IN THE COVER HOUSING TO VENT THE SAID OTHER ENDS OF THE PISTON CHAMBERS TO THE RESPECTIVE GEAR AREAS, SAID PLURALITY OF PISTON ELEMENTS BEING ADAPTED TO ACT IN CONCERT TO IMPOSE UPON THE THRUST PLATE MEANS VARIABLY AXIALLY DIRECTED FORCES FOR SEALING THE ADJACENT SIDES FACES OF THE GEARS AS A FUNCTION OF VARIATIONS IN FLUID PRESSURE EXISTENT BETWEEN THE PLURALITY OF CONNECTIONS OF THE PISTON CHAMBERS TO THE GEAR CHAMBERS, THE AREA OF SAID REMOTE SURFACE OF SAID THRUST PLATE MEANS WHICH IS NOT ENGAGED BY SAID PISTON ELEMENTS BEING VENTED TO A GEAR CHAMBER PRESSURE LESS THAN DISCHARGE PRESSURE.