Reversible pump

E. S. WITCHGER

REVERSIBLE PUMP

April 8, 1958

Filed May 31, 1955

2,829,602

Sheets-Sheet 1

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INVENTOR.

E.S. W/TCHGER

BY

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ArraeMT/s

April 8, 1958

E. S. WITCHGER

2,829,602

REVERSIBLE PUMP

Filed May 31, 1955

Sheets-Sheet 2

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/6

F/G. 2.

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F/G. 4INVENTOR.

£.3. W/TCHGER

BY

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2,829,602

Patented Apr. 8, 1958

United States Patent Office

2,829,602 reversible pump ^ΕΕΧ⁸λ^^Μ&lt;?Τ’·^6Γ0Λ^{8β Poinfe}’ Mich., assignor to co^aSof Mio^{8 C}°^mPaDy’ ^CIeVe3aBd’ ^Ohi0’ ^a

Application May 31, 1955, Serial No. 511,934

Claims. (CI. 103—126) ^Thi? '^nventl0“ 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 flnu/r “^a?,^{CalIy operatiye t0} 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 ^^ew?t^Sh°Y^{n m},^U· ^S’ ^{Patent No}· 2,373,368 to Eugene b. 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 effecting a more immediate adaptation to rotation reversals, by schemes for providing an increased engagement between rotor members. One such improvement is 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.

•¹¹ iV J^Urt^^er °^{b,ect of the present} invention to provide simplified, effective, economical means for enhancing the response of reversible, unidirectional flow gear pumps. ’ ⁶

It is a further object of this invention to provide a pump haying 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 plrci}“.^ar actions 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 the end cover removed of the pump in Fig. 1, ’

Fig. 3 shows an end view of the pump cover plate shown m Fig. 1; and

Fig. 4. shows in cross-sectional side view a pump incorporating modifications of the present invention.

According to the present invention a gear type rotary pump is provided haying 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 portions 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 there° j A ?^{air of} ™”^{er 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 ¹ 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 pro45 vided 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 50 itmer 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 _5g axial key portion 25 and a radial portion 29 affixed to shaft 14. Rotor 28 is not affixed 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 60 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 65 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 Vs of a circle. The curvature 70 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 A—B and B—C to the other thereof. The centers of curvature of each of

3,839,602 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 A__B to surface B—C is expedited by the action of spring 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 26 against end cover plate 22. Because of the friction between rotor 28 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 z8 and a ball drive of the driven rotor 26. As shown in Fig. 4 a ball 40 is located between rotor 26 and. shaft 14 in the adja30 cent 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 35 shown also in Fig. 4, the separation of rotors 26 and 28 is accomplished by the axial bias of diametrically oppose springs 50 and 51 to effect the desired drag to facilitate a quick response of the pump in a manner similar to mat already explained hereinabove with respect to other embodiments of the invention. _m ...

While the present invention has been descrioed 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 modifica45 tions may be made therein and that the end.drag on the driven inner rotor may be 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.