US1952834A - Pump - Google Patents

Description

- E. w. BEIDLER ET AL,

PUIP

March 27, 1934..

Filed Aug. 26. 1952 ZSheets-Sheet 1 aw. mug

. March I934- E; w. BEIDLEREI' u. 1,952,834

Filed Aug. 26, 1932 2 Shanta-Shut 2 Patented M". 27, 1934 PUMP Elliott'W. Badm avon,

and wuwin L. we.

yrla Ohio Application August 26, 1932, Serial No; 630,566

' 20laims.

This invention relates to a sliding vane type of rotary pump and has for itsprincipal object to provide a more efllcient pump which is less likely to stick or to wear excessively in the region of the outlet port. v

A further object is to provide such a pump having a vane provided with rockers at the end thereof affording an extended area of contact with the wall of the pump chamber, maintaining a constant effective length and reducing to a minimum the pressure exerted on the rockers by the fluid passing through the pump.

Other and more limited objects will become apparent from the following description when taken in connection with the accompanying drawings in which Fig. 1 is a transverse section taken through a pump embodying our invention; Fig. 2 is a similar section of a modified form employing two vanes at right angles; Fig. 3 is a view showing one method of constructingthe vanes in the modification of Fig. 2 and Fig. 4 is a similar view showing another method of constructing said vanes; Fig. 5 is a schematic diagram showing the outline of the cross section of thepump chamber in comparison with the circle an arc of which forms a portion thereof, the various positions of the vane or vanes and the locus of the center of the vane or vanes; Fig. 6 is a diagram showing in full line the circle which is shown partially in dotted lines in Fig. 5 and showing indotted line the path traced by one end of the vane when the other end follows said circle as well as construction lines used in developing the equation of the dotted. line curve; and Fig. 'l is a diagrammatic view showing one of the rockers in cross section and indicating the radiiof the two curved surfaces of which it is made up.

Referring now to the drawings, the numeral 10 indicates the body of the pump having formed therein a pump chamber 11 and inlet and exhaust ports 12 and 13 communicating with the chamber 11 in the region of the portion of said chamber which is circular in cross section. J ournaled in suitable bearings at the ends of the chamber 11 is a rotatablemember 14 having a-slot therein receiving slidably a vane 15. It will be understood that the member 14 is connected with a suitable shaft extending to the outside 01' the pump body at one end through a suitable packing gland for connection to a prime mover.

The vane 15 is made up of a central portion 15* which extends nearly entirely across the chamber 11 at-all times but nopart of which ever actually contacts the wall thereof. At each end of the central portion 15 is provided a part cylindrical socket 15 which receives a rocker 18. Each of the rockers 16, as will be clear from Fig. 7, has two curved surfaces one of which is partially cylindrical and received in a socket 15 of the same curvature while the other has the curvature of the circular portion of the chamber 11. That is; the radius of curvature of the rocker 16 which engages the wall of the chamber 11 has a length, a, (Fig. 6) equal to the radius of the guide circle R. The curved surface of the rocker which is received in the socket 15 has its center of curvature in or substantially in the other .curve. In this way, we attain a constant effective vane'length and no clearance need be allowed to compensate for the different positions of the rockers with respect to the central portion of the vane. Inasmuch as the point of greatest tendency to wear is in the region of theexhaust port 13 where more than half of the central vane portion is on the other side of the center of rotation, the resultant 78- centrifugal force .on the central vane portion in that region will be transmitted to the chamber wall through the rocker at the other end and the rocker traversing the wear region will be urged by its own centrifugal force only into contact with 8 *the wall of the chamber. By employing a very light rocker we are able to secure a minimum of friction dueto centrifugal force and by the special construction of the rocker as already explained, we may employ theminimum ofclear- 35 ance whereby an exceedingly close. working relation of the parts is secured.

, By making the pump chamber 11 of a special cross-sectional shape hereinafter described we are able to secure a low rate of change 'of the angle of the rockers 16 with respect to the vane portion 15 in the region of the exhaust port where greatestwear occurs in pumps of this general type and a low total change of angle over this region. While wehave shown a chamber having across section comprising a composite curve made up ofla circlearc less than a semicircle and a portion of another curve tangent thereto at its ends, it is to be understood that we may employ a portion of instead of thecircle arc such as, for-example, a portion of an ellipse whose major and minor axes do not differ greatly, and wherever the terms circular, circle arc or the like are employed herein, they are to be such other similar curves and not to be read in a literal sense. It is our belief that the true circle arc is the best curve to employ since it overcomes the sticking which sometimes occurs in pumps having a limacon cross section at the same 110 another similar curve understood as including bore the cross section of which was defined by the polar equation,

r=a-b cos A,

where 1' is the distance from the origin, A is the angle from the axis of reference, and a and b are constants. This equation is that of a limacon.

The polar equation defining the cross section of our improved pump will now be derived, having reference to Fig. 6, wherein the line MN represents the vane 15 having a length d, the circle R is a hypothetical guide circle along which if one end of the vane moves the other will trace the curve S, the point 0 is the center about which the vane rotates, being free to slide longitudinally of itself, 1' is the distance of the end N of the vane from the origin, A is the angle between the vane MN and ter of the circle R, 1) minus 1', a is the radius of the circle the distance between 0 and P.

In any triangle the relation between the sides a, b and c and the angle A opposite the side a is expressed by the equation,

known as the cosine law. Applying this law to the triangle MOP in Fig. 6,

is a variable equal to d R and c is d =b +c 2bc cos A Transposing,

b =a -c +2bc cos A (1) But,

b=d-T (2) With the aid of Equations (1) and (2) it is possible to plot the curve S. Equations (1) and (2) may be combined to give a less convenient but more illuminating equation.

It will be noted that this equation contains only the two variables, 1' and A, and that it is in as nearly as possible comparable form to the equa;

tion for the limacon,

1=a-b cos A.

from which it difiers radically.

The center of the vane in a limacon type of pump always traces a true circle whereas in our pump it traces the path indicated at Z, a comrelated to the cross section of'the chamber 11. I

In Figs. 2, 3 and-.4 wehave illustrated a double T vane type of pump. inwhienithelbody portion 10 is provided witha*chainber 11f similar to that shown inFig. 1 and .which communicate ports 12 and is. rheymtefor this type differs the reference axis'Y, P is the cen- I in that the member 14 is provided with intersecting slots receiving slidable vanes 18 and 19 of the same construction as that of the vane 15 with the exception of means for accommodating the vanes to each other. Inv Fig. 3, the vanes 18 and 19 have oppositely extending slots 20 and 21 while in the form shown in Fig. 4 the vane 18 is made in two parts afiording a restricted central portion while screw 19 is provided with a central opening 22.

Whilewe have shown and described illustrative embodiments of our invention, we wish it understood that we are not limited to the details thereof but only in accordance with the spirit and scope of the appended claims.

Having thus described our invention, claim is: I i

1. In a pump, a body having formed therein a right, composite, cylindrical cavity provided with inlet and outlet ports, an eccentricmy mounted rotor in said cavity provided with a sliding vane having extended surface contact with opposed portions of said cavity in all positions, said vane being of constant length and made up of a unitary central portion of a length just short of enough to contact the wall of said cavity at both ends having sockets formed in its ends and rockers received in said sockets and having a working fit with the curved wall of said cavity, said cavity having a cross section made up of a circle are less than a semicircle and a portion of a curve what we tangent to said arc at its ends, and said rockers each having a wall engaging face of curvature substantially that of said'circle arc and a cylindrical socket engaging face curved about a center lying in said wall enga in face.

2. In a pump, a body having formed. therein a right, composite, cylindrical cavity provided with inlet and outlet ports, an eccentrically mounted rotor in said cavity provided with a sliding vane having extended surface contact with opposed portions of said cavity in all positions, said vane being of constant length and made up of a unitary central portion of a length just short of enough to contact the wall of said cavity at both ends having sockets formed in its ends and rockers received in said sockets and having a working fit with the curved wall of said cavity, said cavity having a cross section made up of a circle are less than a semicircle and a portion of a curve tangent tosaid arc at its ends, saidcurve being of the form where r is the distance of one end of the vane from its center of rotation, d is the length of the vane, a is the radius of the circle arc, c is the distance of the center of rotation of the vane from the center of said are and A is the angle between said vane and a reference axis passing through the center of rotation of the vane and the center of said are, and said rockersfeach having a wall engaging face of curvature substantially that of said circle arc and a cylindrical socket engaging face curved about a center lying in said wall engaging face.

ELLIOTT W. BEIDLER. WALWIN L. DAVIS.

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