Reversible pump

E. S. WITCHGER

REVERSIBLE PUMP

Filed April 7, 1944

<img file="US2373368A_D0001.tif" />

<img file="US2373368A_D0002.tif" />

F/G.8.

<img file="US2373368A_D0003.tif" />

F/5. 3. F/G. 4.

INVENTOR.

BY

<img file="US2373368A_D0004.tif" />

Patented Apr. 10, 1945

2,373,368

UNITED STATES PATENT OFFICE

2,373,368

REVERSIBLE PUMP

Eugene S. Witchger, Grosse Pointe Woods, Mich., assignor to Eaton Manufacturing Company, Cleveland, Ohio, a corporation of Ohio

Application April 7,1944, Serial No. 530,014

Claims. (Cl. 103—126)

This invention relates to pumps and particularly to pumps of the rotary type having cooperating internal and external rotors, the principal object being the provision of a pump of this type that is automatically reversible so that regardless of the direction of rotation it continually pumps in the same direction.

Objects of the invention include the provision of an automatically reversible pump; the provision of a rotary pump which will continuously pump in the same direction regardless of the direction of rotation thereof; the provision of a pump having pumping means comprising a pair of rotors one within and eccentric to the other and having interengaging teeth forming pumping chambers between them, inlet and outlet ports communicating with such pumping chamber, and the outer of the rotors being so shiftable in the direction of its plane of rotation between two different limiting positions that the expanding pumping chambers formed between the teeth of the rotors remain continuously in open communication with the inlet port and the contracting pumping chambers formed between the teeth of the rotors remain continuously in open communication with the outlet port; the provision of a construction as above described in which the outer rotor is automatically shifted between the limits of its shiftable movement by the pumping force exerted between the rotors; the provision of a construction as above described in which the pumping chamber provides surfaces for engagement with the outer rotor to limit the shiftable movement therewith and forming bearing surfaces therefor; and the provision of a pump of the general type described that is simple in construction, efficient in operation, and economical to manufacture.

The above being among the objects of the present invention the same consists in certain novel details of construction and combinations of parts to be hereinafter described with reference to the accompanying drawing, and then claimed, having the above and other objects in view.

In the accompanying drawing which illustrates a suitable embodiment of the present invention and in which like numerals refer to like parts throughout the several different views,

Fig. 1 is a vertical sectional view, taken axially through a pump constructed in accordance with the present invention, as on the line i—i of Fig. 2;

Fig. 2 is a transverse sectional view taken on the line 2—2 of Fig. 1 and showing the rotors in end view, with the rotors in the relative positions

11) which they assume when turning in. a clockwise direction of rotation;

Fig. 3 is a view similar to Fig. 2, but with the rotors removed from the housing, showing the inlet and outlet ports; and,

Fig. 4 is a view similar to that in Fig. 2, but showing the rotors in the relative positions which they assume when rotating in a counterclockwise direction of rotation.

The pump of the present invention employs cooperating rotor elements conforming generally to tnose disclosed in United States Letters Patent Nos. 1,682,564, dated August 28, 1928, and particularly United States Reissue Patent No. 21,316, dated January 9, 1940, both to Myron F. Hill, or to any mecnanicaliy equivalent structure. In other words, it has particular relation to tnat type of pump including a pair of toothed rotors, one within and eccentric to the other and having at least one less tooth division than the other, the teeth having diametrically opposed full mesh and open mesh positions and preferably remaining in substantially contacting relationship with respect to each other between such positions. One rotor is driven, thus driving the other of the rotors through the inter-engagement of their respective teeth and as the interengaging teeth move away irom the full mesh position in the direction of rotation they open between them pumping chambers which continue to increase in. volume to open mesh position and which chambers decrease in volume from open mesh position to full mesh position in the direction of rotation. In the drawing, the inner rotor is indicated at 10 and the outer rotor at 12, the inner rotor being shown as having four teeth 14 and the outer rotor as having five teeth 16.

It has been conventional practice to provide such rotors in a pump structure and each for rotation about a fixed axis, the pump housing being provided with an inlet port communicating with those pumping chambers increasing in volume and an outlet port communicating with those pumping chambers decreasing in volume. Because of the fact each such rotors has each been mounted for rotation about a fixed axis, it will be appreciated that if the direction of rotation of the pump is reversed the pumping chambers of increasing volume are shifted from one side of a medial plane including the full mesh and open mesh positions to the opposite side thereof and consequently the direction of flow of fluid through the pump is correspondingly reversed. In accordance with the present invention, instead of mounting the outer rotor for rotation about a fixed axis as in prior constructions, it is mounted so as to be capable of a bodily shiftable movement in the plane of its rotation, and its shiftable movement in either direction is so limited that regardless of which limit of its shiftable movement it is in the pumping chambers of increasing volume remain in open communication with one of the ports only, while the pumping chambers of decreasing volume remain in open communication with the other of the ports only. The bodily shiftable position of the outer rotor is automatically controlled by the direction of rotation of the rotors, the pumping force set up between them automatically effecting the required movement of the outer rotor. Thus, the pump will operate to pump continuously in one direction regardless of its direction of rotation, this being extremely important in many installations as will be readily appreciated by those skilled in the art.

The actual form of the pump embodying the present invention may, of course, vary widely, the form shown in the drawing for the purpose of illustration being of an extremely simple type for ease in description. As shown, it comprises a cast body indicated generally at 20 having a pumping chamber indicated generally at 22 opening onto one end face thereof, which face is normally closed by a cover or cap member 2* secured thereto by means of screws 26. A shaft 28 is rotatably supported.in the housing 20 and projects through the pumping chamber 22, its outer or righthand end, as viewed in Fig. 1, bearing in a suitable bore 30 provided concentrically therewith in the cover or cap member 24. The inner rotor 10 is received on the shaft 20 within the pumping chamber 22 and is secured thereto for equal rotation as by means of a key 32. The rotor 10 is preferably of substantially the same axial length as the distance between the inner wall of the cap member 24 and the bottom of the pumping chamber 22, only that amount of axial clearance being preferably provided for the rotor which is necessary for a running fit. If desired, relative axial movement between the drive shaft 28 and the inner rotor 10 may be prevented by means of snap rings 34, one snapped into each of co-operating circumferential grooves formed in the shaft 28 at each end of the rotor 10.

The rotor i2 surrounds the rotor 10 in the chamber 22 in the relation described and cooperates with the inner face of the cap member 24 and the bottom wall of the pumping chamber 22 in the same manner as the rotor 10. Although, in the broader aspects of the invention, the rotor 12 may be provided with a surrounding bearing or other member, in the construction shown and by way of simplicity, the bearing for the rotor 12 is provided by direct contact with peripheral wall portions of the pumping chamber 22, the pumping chamber 22 being of materially larger size than the outer rotor 12 so that the latter may shift bodily therein in the plane of its rotation.

In order to limit the bodily shiftable movement of the outer rotor 12, the peripheral wall of the pumping chamber 22 is formed to provide three distinct areas, one extending from a point indicated at A to a point such as indicated at B, another extending from the point A in the opposite direction to a point indicated at C, and the third constituting the remainder of the peripheral walls of the chamber 22 and extending from B to C, the latter being generally disposed at a greater distance from the axis of the shaft 28 than the first two surfaces so as to provide ample clear3,373,868

Ti ance in the chamber 22 for the shifting of the outer rotor 12.

The surfaces A—B and A—C are substantially quarter circular in plan view as shown in Figs. 2, 3, and 4 and each is of a radius equal to the radius of the peripheral surface of the outer rotor i 2. The center of curvature for the surface A—B is indicated at D, best shown in Fig. 3, and the center of curvature for the surface A—C is indicated at E, these centers D and E being equally disposed on diametrically opposite sides of the center of rotation of the inner rotor 10 which, as indicated, is the axis F of the shaft 28. The distance between the center F and each of the centers D and E is equal to the eccentricity of the rotors 10 and 12 so that when the outer rotor 12 is lying in contact with the surface A—C, as viewed in Fig. 2, or in contact with the surface A—B, as shown in Fig. 4, it is rotatably supported in the proper eccentric relation with respect to the inner rotor 10 in both cases. The surfaces A—B and A—C not only serve as bearing surfaces for the outer rotor 12, but also serve as stop surfaces which limit bodily shiftable movement of the outer rotor (2 in either one direction or the other in the plane of its rotation in the chamber 22 as will be readily appreciated.

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 inner rotor and 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 F on, and the axis of the shaft 28, and including the points D and E. Consequently when the outer rotor 12 is in the position shown in Fig. 2 where its axis of rotation is the point E, the point of full mesh between the teeth of the rotors will be at the lefthand side of the pump in horizontal alignment with the axis of the shaft 28 and the position of open mesh will be at a diametrically opposite point on the righthand side of the shaft 28. Conversely when the rotors are in the position illustrated in Fig. 4 the axis of rotation of the outer rotor 12 will be the point D under which conditions the above relation of parts will be reversed, that is, the point of full mesh will lie on the righthand side of the shaft 28 in horizontal alignment with the axis of the shaft 28 and the point of open mesh will lie diametrically opposite from the axis of the shaft 28 therefrom.

The pumping action in a pump of the type described is obtained through pumping chambers which are 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 in the drawing where the outer rotor 12 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 left-hand side of the center F of the shaft 28 and in horizontal alignment therewith and the pumping chambers formed between the teeth (4 and (6 of the rotors 10 and 12 and increasing in volume lie above the axis of the

2,373,308 shaft 28 while those decreasing in volume lie below the axis of such shaft.

Similarly, and as brought out in Fig. 4, when the outer rotor 12 is in the position indicated in Fig. 4 the point of full mesh is in horizontal align- 5 ment with the axis F of the shaft 28 but to the right of the axis F of the shaft 28 while the open mesh position is on the diametrically opposite side of the shaft 28. However, it will be appreciated that in this last case and when the rotors 10 and 10 12 are turning in the direction of the arrow shown in Fig. 4 identifying the direction of rotation and which is opposite to that shown in Fig. 2, the expanding chambers formed between the teeth of the rotor still lie above the axis at the shaft 28 while the contracting chambers formed between the teeth still lie below the axis F of the shaft 28. In other words, regardless of whether the relative positions of the rotors 10 and 12 are that illustrated in Fig. 2 or that illustrated in Fig. 4, when ₂₀the rotors are turning in the respective directions illustrated in these views, the expanding pumping chambers formed between the teeth of the rotors always lie above the axis of the shaft 28 and the contracting pumping chambers formed between such teeth always lie below the axis of the shaft ²⁸28. Consequently the inlet port 40 formed in the inner wall of the pumping chamber 22 is always in open communication with the expanding pumping chambers formed between the teeth of the „ rotor, and the similarly formed outlet port 42 ^Jformed in the inner face of the chamber 22 is always in open communication with the contracting pumping chambers, regardless of whether the rotors are in the position illustrated in Fig. 2 or „„ in the position illustrated in Fig. 4.

The outer rotor 12 is automatically shifted to the position illustrated in Fig. 2 when the pump is rotating in the direction illustrated in Fig. 2 by the pressure built up between the teeth of the rotors cooperating to form contracting pumping chambers, and likewise is automatically shifted to the position illustrated in Fig. 4 for the same reason whenever the direction of rotation of the pump is reversed from that indicated in Fig. 2. ₄₅Thus, the outer rotor 12 is shifted between its limits of shiftable position indicated in Figs. 2 and 4 automatically whenever the direction of rotation of the pump is reversed and in accordance with the direction of rotation of the pump. 50 It will be appreciated that the outer rotor 12 in shifting in the manner described from a position in which its axis of rotation is on one side of the axis of the shaft 28 to a position in which its axis is on the diametrically opposite side, in effect is ₆₅bodily shifted, or rotated, about the axis of the shaft 28 through an angle of 180°. The extent of such angularity is not critical as it will be appreciated that any angularity sufficient to reverse the effective relation of the ports with respect to the points of full mesh and open mesh of the rotors will ordinarily suffice.

The expanding chambers formed between the cooperating teeth of the pumping elements form, of course, chambers in which the fluid being _epumped is drawn through the inlet port 40, and the fluid expressed between the teeth cooperating to form contracting pumping chambers is, of course, delivered into the outlet port 42. The housing 20 is, of course, provided with a suitable ₇₀inlet passage such as 50 communicating with the inlet port 40 and a similar discharge passage 52 communicating with the discharge port 42.

It will thus be appreciated from the foregoing that by means of the present invention a pump 75 of the rotary type is provided in which the direction of flow of fluid through the pump remains constant regardless of the direction of rotation of the pump and that this important feature is obtained in a simple and effective manner and without requiring the addition of any parts whatsoever as compared to similar types of pumps in which the direction of flow of fluid is reversed upon reversal of the direction of rotation of the pump.