US2829602A

US2829602A - Reversible pump

Info

Publication number: US2829602A
Application number: US511934A
Authority: US
Inventors: Eugene S Witchger
Original assignee: Eaton Manufacturing Co
Current assignee: Eaton Corp
Priority date: 1955-05-31
Filing date: 1955-05-31
Publication date: 1958-04-08
Anticipated expiration: 1975-04-08

Description

April 8, 1958 E. s. WITCHGER V REVERSIBLE PUMP 2 Sheets-Sheet 1 Filed May 51, 1955 INVENTOR. 5. W/TCf/GER April 8, 1958 E. s. WITCHGER 2,829,602

REVERSIBLE PUMP Filed May 51, 1955 2 Sheets-Sheet 2 INVENTOR. 3. VV/TCHGER United States Patent REVERSIBLE PUMP Eugene S. Witchger, Grosse Pointe, Mich., assignor to Eaton Manufacturing Company, Cleveland, Uhio, a corporation of Ohio Application May 31, 1955, Serial No. 511,934 9 Claims. (Cl. 103-426) This invention relates to pumps and more particularly to unidirectional flow, reversible pumps.

Broadly the present invention comprehends the provision of a rotary type pump having cooperable, eccentric, inner and outer rotors and being so constructed as to be automatically operative to provide unidirectional flow from intake to discharge ports irrespective of the direction of rotation of the pump rotors.

In the past, reversible, unidirectional flow pumps of the type shown in U. S. Patent No. 2,373,368 to Eugene S. Witchger have been devised and operated with much success. It has, however, been discovered that such pumps can be rendered more responsive, that is, capable of eifecting a more immediate adaptation to rotation reversals, by schemes for providing an increased engagement between rotor members. the subject matter of U. S. Patent No. 2,458,678 to George F. Bunte. Prior art arrangements for improving response, however, are unduly complicated and employ a number of parts requiring fine, detailed machining operations increasing the cost thereof.

It is accordingly an object of the present invention to provide an improved, more responsive, reversible, unidirectional flow gear pump.

It is a further object of the present invention to provide simplified, effective, economical means for enhancing the response of reversible, unidirectional flow, gear pumps.

It is a further object of this invention to provide a pump having pumping means comprising an outer rotor and a pair of inner rotors within and eccentric to the outer rotor, automatically operative to adapt to reverse rotation of the rotors to provide unidirectional pumping.

It is a further object of the present invention to provide a reversible, unidirectional flow, gear pump and a pumping chamber with the peripheral walls comprising 3 circular sections having displaced centers of curvature and a bipartite inner rotor with means urging the separation of the parts thereof to accomplish a quick shift of the outer rotor from engagement with one circular chamber section to another in response to reversal of rotation of one of the inner rotors.

Other and further objects and advantages will become manifest from the following detailed description taken with the accompanying drawings in which:

Fig. 1 shows a cross-sectional side view of the pump of the present invention,

Fig. 2 shows an end view with of the pump in Fig. 1,

Fig. 3 shows an end view of shown in Fig. l; and

Fig. 4 shows in crosssectional side view a pump incorporating modifications of the present invention.

According to the present invention a gear type rotary pump is provided having a pumping chamber recessed in a pump housing with a generally circular peripheral wall but being comprised of 3 circular sections, each of a third of a circle in circumference. Two of the porthe end cover removed,

the pump cover plate One such improvement is,

tions have equal radii of curvature but with displaced centers of curvature and within the pumping chamber is an outer rotor with a circular outer periphery of the same radius of curvature as the two mentioned portions and shiftable for selective engagement with either thereof. A pair of inner rotors eccentric to the outer rotor and having outer teeth engageable With the teeth on the inner surface of the outer rotor are provided. The inner rotors are axially adjacent each other and like the outer rotor have a combined axial extent substantially equal to the depth of the recess. Each inner rotor has one fewer teeth than the outer rotor and the teeth have, therefore, diametrically opposed full mesh and open mesh positions and intermediate positions in contacting relation with each other.

Provision is made for urging the axial separation of the inner rotors to force at least one of them against the pump housing. Additional provision is made for driving one of the inner rotors so as to impart a rotary motion thereto and to effect a rotary motion of the outer rotor whose teeth are in engagement with the inner rotors. As a consequence the second inner rotor is driven by virtue of its engagement with the outer rotor.

The force tending to separate the inner rotor members causes the driven inner rotor member to rub against an axial limit enclosing the pumping chamber and to cause the rotor member to drag and be displaced angularly by the amount permitted by the clearance between inner and outer rotors. Under these conditions: the shift of the outer rotor from contact with one circumferential portion of the pumping chamber to another is effected quickly and easily upon a reversal of rotation of the driven inner rotor, since the lagging rotor enables a rocking action of the outer rotor at its point of contact with the outer rotor.

Referring now to the drawings for a more detailed description of the present invention 10 represents generally the pump housing having a hollow, narrow elongated portion 12 for receiving a drive shaft 14 and a wide portion 16 provided with a recessed pumping chamber 18 and a plurality of axial holes 19 for receiving bolts 21 to secure an appropriate cover plate 22 to the housing to cover the chamber during operation. Holes: 20 are provided as means to attach the pump housing to a suitable pump carrying member.

Within recess 18 an outer rotor 24 having a smooth circular outer circumference and a geared inner circumference is provided and within rotor 24 are a pair of inner rotors 26 and 28 having geared outer peripheries in engagement with the gears of rotor 24. Each of the inner rotors has 12 teeth or one fewer than the number of teeth on rotor 24, viz., 13. Rotor 26 is affixed to shaft 14 for rotation therewith by a plate 23 having an axial key portion 25 and a radial portion 29 affixed to shaft 14. Rotor 28 is not afiixed to any other component of the system. Each of rotors 26 and 28 is recessed along adjacent portions to provide room for a Bellville type or washer spring 27 for urging the separation of the rotors.

The pumping chamber 18 has an outer wall with 3 sections, each comprising an arc of a circle. The first section extends from A to B, the second section from B to C and the third section from C to A, as seen most clearly in Fig. 2. The curvature of each of the first 2 named sections is the same as that of rotor 24 so as to provide even mutual engagement with the rotor under certain conditions as set forth hereinbelow and the extent of each is approximately /3 of a circle. The curvature of the third section is not critical, it being necessary only to provide sufficient space for rotor 24 to shift unimpeded from engagement with either of sections AL-B and B-C to the other thereof; The centers of curvature of each of asaaeoa the sections A---B and B-C are displaced from each other as shown at D and B, respectively, and are displaced equally on opposite sides of the center F of rotor 26. The distance between the center F and each of the centers D and E is equal to the eccentricity of the

rotors

24 and 26 so that when the outer rotor 24 is lying in contact with the surface AB or in contact with the surface B-C, it is rotatably supported in the proper eccentric relation with respect to the inner rotor 26 in both cases. The surfaces A-B and B-C not only serve as bearing surfaces for the outer rotor 24, but also serve as stop surfaces which limit bodily shiftable movement of the other in the plane of rotation in the chamber 1% as will readily beappreciated.

It will be understood that in a pump having pumping elements of the type described the positions of full mesh and open mesh of the teeth of the pumping element will be in a plane including the axis of rotation of the outer rotor. In the construction shown and as viewed in the drawing this plane is a horizontal plane perpendicular to the plane of the paper including the point P, and the axis of the shaft 14, and including the points D and E. Consequently when the outer rotor 24 is in a position as shown in Fig. 2 Where its center coincides with point D, the point of full mesh between the teeth of the rotors will be at the right-hand side of the pump in horizontal alignment with the axis of the shaft 14 and the position of open mesh will be at a diametrically opposite point on the left-hand side of the shaft 14. Conversely when the rotors are in a position so that the axis of outer rotor 24 coincides with the point E under which conditions the above relation of parts will be reversed, that is, the point of full mesh will lie on the left-hand side of the shaft 14 and the point of open mesh will be diametrically opposite from the axis of the shaft 14 therefrom.

The pumping action in a pump of the type described is obtained through pumping chambers whichare opened up, or increase in volume, as the teeth move from full mesh position in the direction of rotation of the pumping element to open mesh position, and through contraction or closing of such pumping chambers as the teeth of the two rotors move from open mesh position in the direction of rotation of the rotors to full mesh position. Thus in the construction shown where the outer rotor 24- is in the position indicated in Fig. 2 and the rotors are turning in the direction of the arrow identifying such direction in that figure, the full mesh position is at the right-hand side of the center F of the shaft 1 and in horizontal alignment therewith and the pumping chambers formed between the teeth of the

rotors

24 and 26 and increasing in volume lie below the axis of the shaft 14 While those decreasing in volume lie above the axis of such shaft.

Similarly when the outer rotor 24 is in a position that its center coincides Wit point B, rotor 24 will engage surface B-C of chamber 13 and the point of full mesh is in horizontal alignment with the axis P on the left hand side of the shaft 14 while the open mesh position is on the diametrically opposite side of the shaft. However, it will be appreciated that when the rotors are turning in a direction reverse to that indicated by the arrow in Fig. 2 the expanding chambers formed between the teeth of the rotor will lie below the axis of the shaft 1 while the contracting chambers formed between the teeth still lie above the axis F of the shaft in other words, irrespective of the relative positions of the rotors 2d and 26 the expanding pumping chambers formed between the teeth of the rotors always lie below the axis of the shaft 14 and the contracting pumping chambers formed between such teeth always lie above the axis of the shaft 14. Consequently an inlet port 3b formed in the cover plate 22 is always in open communication with the expanding pump ing chambers formed between the teeth of the rotor, and a discharge port is always in open communication with the contracting pumping chamber formed between the teeth of the rotor. inlet port 30 communicates with a chamber 31 formed in the cover plate 22 and discharge port 32 communicates with a chamber 33 also formed in the cover plate. Chambers 31 and 33 are shown in cross-sectional contour more clearly in Fig. 3 of the drawings.

The outer rotor 24 is automatically shifted to a position to engage surface B-C of the pumping chamber upon reversal of rotation of inner rotors 26 and 28. According to a feature of the invention the response of the pump, that is, the shift of rotor 24 from contact with surface AB to surface B-C is expedited by the action of spring 27 applied between rotors 26 and 28. Spring 27 forces rotor 28 against the pocket or bottom of pumping chamber 18 and equally and oppositely tends to force rotor 25 against end cover plate 22. Because of the friction between rotor 23 against the pocket a drag tending to retard the rotation of rotor 28 is applied thereto and this rotor lags behind inner rotor 26 by the amount of clearance between inner and outer rotors. This mismatch enables the rotor set to adapt for reverse rotation thereof immediately since the driven inner rotor 28 tends to retard the rotation of outer rotor 24 and induces a rocking action thereof to shift to an adjacent stopping surface and operate in a manner explained hereinabove.

In accordance with a modification of the invention, a simplification is effected as shown in Fig. 4 by the provision of an interchange of rotors 26 and 28 and a ball drive of the driven rotor 26. As shown in Fig; 4 a ball 49 is located between rotor 26 and shaft 14 in the adjacent recessed portions of each. Spring 27 is located similarly as in Figs. 1 and 2 and performs a similar function. It is to be understood that drag on driven inner rotor 28 is effected by friction between rotor 28 and cover plate 22.

In a further modification of the present invention as shown also in Fig. 4, the separation of rotors 26 and 28 is accomplished by the axial bias of diametrically opposed springs 50 and 51 to effect the desired drag to facilitate a quick response of the pump in a manner similar to that already explained hereinabove with respect to other embodiments of the invention.

While the present invention has been described with reference to certain specific embodiments thereof, it is readily obvious to those skilled in the art to which the invention appertains that many changes and modifications may be made therein and that the end drag on the driven inner rotor maybe obtained in many different ways without deviating from the spirit or scope of the invention. It is, accordingly, intended that it be limited as set forth in the appended claims.

What I claim is:

1. A pump structure comprising a housing having a. chamber therein, pumping means in said chamber comprising an outer rotor member and a pair of inner rotor members eccentric to said outer rotor member, said outer rotor having interengaging teeth with each of said inner rotors, means for supporting and driving a first of said inner rotors about an axis fixed with respect to said housing, a second of said inner rotors being freely floating with respect to said first inner rotor driving means and said outer rotor, said outer rotor being bodily shiftable in said mentioned chamber in a plane perpendicular to said axis between two relatively different positions, said housing having inlet and outlet port means opening into said pumping chamber, said ports maintaining the same pumping action irrespective of which of said positions said outer rotor is in, and means cooperative with said inner rotors to facilitate a quick response of said. pump to rotation reversals of the first of said rotors.

2. A pump structure according to claim 1 wherein said last mentioned means comprises spring means interposed between said inner rotors urging the axial separation of said inner rotors and thrust absorbing surfaces axially adjacent each of said inner rotors with the second of said inner rotors being brought into engagement with its associated thrust absorbing surface.

3. A pump structure comprising a housing having a chamber therein, pumping means in said chamber comprising an outer rotor member and a pair of inner rotor members eccentric to said outer rotor member, said outer rotor having interengaging teeth with each of said inner rotors, means for supporting and driving a first of said inner rotors about an axis fixed with respect to said housing, a second of said inner rotors being supported on and rotatable with respect to said first inner rotor driving and supporting means, said outer rotor being bodily shiftable in said mentioned chamber in a plane perpendicular to said axis between two relatively different positions, said housing having inlet and outlet port means opening into said pumping chamber, said ports maintaining the same pumping action irrespective of which of said positions said outer rotor is in, means cooperative with said inner rotors for urging the separation thereof and a pair of thrust absorbing surfaces, forming a portion of the housing and outwardly disposed axial end of each adjacent one of said inner rotors.

4, A pump structure comprising a housing having a chamber therein, pumping means in said chamber com prising an outer rotor and a pair of axially adjacent inner rotors eccentric to said outer rotor, said outer rotor having interengaging teeth with each of said inner rotors, the adjacent surfaces of said inner rotors being recessed, means located in said recesses for axially biasing said rotors away from each other, axially opposed thrust absorbing surfaces adjacent axially opposite surfaces of said inner rotors, means for supporting and rotating a first of said inner rotors about an axis fixed with respect to said housing, the second of said inner rotors being supported and rotatable about said axis and being driven by said outer rotor whereby said second inner rotor lags angularly behind said first inner rotor due to the clearance between outer and inner rotors, said outer rotor being bodily shiftable in said mentioned chamber in a plane perpendicular to said axis between two relatively difierent positions, said housing having inlet and outlet port means opening into said pumping chamber, said ports maintaining the same pumping action irrespective of which of said positions said outer rotor is in whereby the drag of said second rotor facilitates a rapid response of said pump.

5. A pump according to claim 4 wherein the recessed surfaces of said inner rotors are annular in shape.

6. A pump structure according to claim 5 wherein said means located in the recesses of said inner rotors is a washer spring.

7. A pump structure comprising a housing having a chamber therein and a cover plate covering said chamber, pumping means in said chamber comprising an outer rotor member and a pair of adjacent inner rotor members eccentric to said outer rotor member, said outer rotor member having interengaging teeth with each of said inner rotors, said inner rotors and said outer rotor having an axial extent equal to the axial extent of said chamber, means for supporting and driving a first inner rotor adjacent said cover plate about an axis fixed with respect to said housing, the second of said inner rotors being driven only by said outer rotor, said outer rotor being bodily shiftable in said mentioned chamber in a plane perpendicular to said axis between two relatively ditferent positions, said housing having inlet and outlet port means opening into said pumping chamber, said ports maintaining the same pumping action irrespective of which of said positions said outer rotor is in, means cooperative with said inner rotors for urging the separation thereof, said cover plate and the axial end of said chamber absorbing the thrust of said inner rotors whereby the second inner rotor is caused to drag to facilitate a rapid shift of said outer rotor from one of said positions to the other to accommodate reversals of said driving means.

8. A pump structure accrding ltO claim 3 wherein said means urging the separation of said inner rotors comprises a pair of springs diametrically, oppositely disposed between said inner rotors.

9. A pump structure according to claim 8 wherein the means for driving one of said inner rotors comprises a shaft rotatable about said axis, and additionally comprising a pair of adjacent opposed recesses in said shaft and the first of said inner rotors and a rigid ball located in said recesses to afford drive between said shaft and said rotor by virtue of shear resistance of said ball.

References Cited in the file of this patent UNITED STATES PATENTS 1,334,906 Keith Mar. 23, 1920 1,964,330 Pitt June 26, 1934 2,373,368 Witchger Apr. 10, 1945 2,458,678 Bunte Ian. 11, 1949 2,492,073 Taylor u Dec. 20, 1949