US2347944A - Rotary pump - Google Patents

Description

E. FOWLER ROTARY PUMP Filed May 22, 1942 May 2, 1944.

2 Sheets-Sheet 1 ELBERT WMQ da BY 16M ATTORNEYS.

y E. FOWLER 2,347,944

I ROTARY PUMP Filed May 22, 1942 Sheets-Sheet 2 c, RCULAR- RC I GENERATED CURVE FIIG.4.

l I D H 13 V E 1 INVENTOR.

ELBERT FOWLER BY f 3 wwflxiv.

- ATTORNEYS Patented May 2, 1944 ROTARY PUMP Elbert Fowler, Elyrla, oiiio Application May 22, 1942, Serial No. 444,016

10 Claims. (01. 103-138) This invention relates, as indicated, to rotary pumps, but has reference mor particularly to rotary pumps of the sliding vane type.

It has heretofore been proposed to construct a rotary pump of this type with a bore comprising concentric arcs connected by means of curved sections in th form of portions of an Archimedean spiral. While such pumps have certain de- 7 sirable operating characteristics, they will not produce an entirely smooth pulsationless flow,

due to the fact that it is virtually impossible to Fig. 3 is an enlarged cross-sectional view of the bore of the pump shown in Fig. 1, and

Fig. 4 is a view, similar to Fig. 3, but showin the modified pump incorporating the aforesaid loin the ends of the non-arcuate curved portions thereof in such a manner as to. avoid the presence of humps or cusps at or adjacent such junctures. This is a defect which is. inherent in the use of Archimedean spiral portions forthis purpose, and cannot be remedied by merely shifting such portions circumferentially of the bore in such a manner as to produce approximate tangency at one or the other of the lunctures, since an attempt to remedy the defect at one juncture merely aggravates the condition at the other juncture.

I have discovered as the result of considerable experimentation and study of the conditions necessary to produce smooth pulsationless flow that I can best secure such flow by the use of a bore having non-arcuate portionsin the form of a generated curve which deviates somewhat from an Archimedean spiral, and the juncture of which with the arcuate portions of the bore is characterized by a condition free from humps, cusps,

or other protuberances or elements tending to interfere with smooth operation.

In one case, I employ a generated curve, which is suitablefor air or gas. compressors or vacuum pumps, in which smooth flow, while desirable, is

not as essential as in a liquid pump. In another case, I employ a generated curve which isespecially adaptable for liquid pumps for fuel and the like, in which smooth pulsationless flow is an essential consideration.

. Inasmuch as the generated curve, in the second case, is derived from the equation of the first-named curve, a pump incorporating the first-named curve in the bore thereof will be first described, such pump being illustrated in Figs. 1,

2 and 3 of the accompanying drawings, wherein Fig. 1 is a view, partly in elevation, and partly in section, of a pump incorporating the aforesaid first-named curve as a part of the bore thereof on the line 2-2 of Fig. 1;

second-named curve in the bore thereof.

Referring more particularly to Figs. 1, 2 and 3 ofth'e drawings, it will be seen that a rotary pump constructed in accordance with the invention comprises a body I having a circular bore 2 into which the stator 3 is fitted and secured against rotation relatively to the body I by means of a key 4. The stator 3 is secured against endwise movement in the body I by means of thrust bearings 5 and 6, which bearings also serve as radial or Journal bearings for the rotor-I oi the pump. The rotor 1 projects beyond one end of the pump body and is provided with a splined extension 8, whereby'the rotor may be driven. a

The rotor I is rotatable about the center 0, which is also the center of the inside of the truly circular arcs Ai-A2, BiB2 of the stator 3. The

rotor, moreover, is provided with slots 9 at right angles to each other and with vanes I0 and I l which are slidable radially in these slots. The vanes l0 and II are cut away as at I! to clear each other, the cut away portions being suilicient inlength to permit the maximum radial movement of th vanes without interference with each other. The outer ends of the vanes are prefe ably fitted with rocker seals IS, the functions of vanes have been designated by the letters CE and DK, these letters also designating the points at which these .center lines intersect the wall of the stator 3. Since both ends of a vane necessarily contact the stator at any point in the rotation of the rotor, the interior of the stator cannot be' circular, but consists in fact, of several curves,

designated respectively as AiA2,B1'B2, A 1B1,

and Aa-Ba.

The curves A1Aa and 31-132 are-truly circular arcs having a common center 0 with the rotor and having radii respectively of 11, equal to the radius of the rotor, plus clearance 01' about .0005", and h+r1, which is equal to the rotor radius plus the excess h of the vane length For convenience in describing the invention, the center lines of the the deviation from pulsationless fiow,'.

R=r1+h Sin wherein R. is the distance from the center 0 to the point on the curve A1-B1 whose position is to be determined, 11 is the radius of the rotor plus running clearance, h is the excess of the vane length over the rotor diameter, d 0 is the angle determined from the equation;

where 0' is the angle between 0A1 and a line drawn from the center 0 to the point on the curve Ai-Bi whose position is to be determined.

Since CF varies as sino, since 0C is 90 from GD, since GD=HE, since sin0+cos=o=1,- and since 1 is a constant, then CE is constant throughout the revolution of the rotor.

It will beapparent from the foregoing that the curve Az-Bz, since it is symmetrically located relatively to the curve A1-B1, is determined or generated in the same manner as the latter.

A pump as described is particularly adapted for air or gas compressors, or as a vacuum pump,

since smooth flow, while desirable in such pumps,

is not as essential as in a liquid pump.

Referring to Fig. 4, wherein is shown a pump especially adapted for: the smooth pulsationless flow of liquids, such as fuel for aeroplanes, and the like, it will be seen that the general constructional features of the pump are similar to those described in connection with the air or gas com- In this case, however, the circular arcs CK and DE extend for 90 degrees and the curve CD is a generated curve which is represented by the equation:

event, the angle 0 in the foregoing equation will be determined in the same manner as in the first form of the invention, 1. e., from the equation Since the generated curves in'all cases, are

number of vanes, and the diillculty of providing sufllcient vane rigidity or strength, where room must be provided for a large number of vanes.

I claim:

1. In a rotary pump of the sliding vane type, a rotor, a pump body having a stator therein, said stator having an internal cross-section defined by two opposite concentric arcs of unequal radii. and vane extending and retracting curves joining adjacent ends'of said arcs, said curves bein generated curves determined by the equation:

wherein R. is the distance from the center of the rotor to the point on the curve whose position is to be determined. 11 is the radius of the rotor plus running clearance, h is the exwherein R. is the distance from the center 0 to pressed as a decimal of h. The exponent m is,

chosen arbitrarily, its value being influenced by whether more or less deviation from pulsationless flow is permissible. Obviously, thegreater the smoother the vane acceleration will be at the ends of the generated curve. A value of 1n=1 gives an excellent curve. The greater the value of m, the smoother will be the vane acceleration, but with greater departure from mathematically pulsatlonless flow. The curve EK is determined in the same way as the curve CD, and is, in fact,

symmetrically disposed with respect to the latter.

- If desired, the arcs CK and DE in the form ofthe invention shown in Fig. 4 need not extend 90 degrees, but may extend through smaller or greater angles, such as an angle a. In that cess of the vane length over the rotor diameter, and 0 is the angle determined from the equation radii, and vane extending and retracting curves joining adjacent ends of said arcs, said curves being generated curves determined by the equation wherein R is the distance from the center of the rotor to the point on the curve whose position is'to be determined, 11 is the radius of the rotor plus running clearance, h' is the excess of the vane length over therotor diameter, 0 is the-angle between a lineioining the center of the rotor and an end of the arc of mailer radius and a line Joining the center of the rotor and the point on the curve whose position is to be determined and m is an exponent whose value varies from V: to 2.

3. In a rotary pump of the sliding vane type, a rotor, a pump body having a stator therein, said stator having an internal cross-section delined by two opposite concentric arcs of about degrees, but of unequal radii, and vane extending and retracting curves, Joining adjacent ends of said arcs, said curves being generated curves determined by the equation wherein R is the distance from the center of the rotor tothe point on the curve whose position is 'to be determined, 11 is the radius of the rotor plus running clearance, h is the excess of the vane length over the rotor diameter, is' the angle between a line joining the center of the rotor and an end of the arc of smaller radius and a line joining the center of the rotor and the point on the curve whose position is to be determined and m is. an exponent whose value varies from to 2.

4. In a rotary pump of the sliding vane type,

a rotor, a pump body having a stator therein, said stator having an internal cross-section defined by two opposite concentric arcs of unequal radii, and vane extending and retracting curves joining adjacent ends of said arcs, said curves being generated curves determined by the equation R=rr+h[sin 0+K sin" (40)] wherein R is the distance from the center of the rotor to the point on the curve whose position is to be determined, 11 is the radius of the rotor plus running clearance, 71. is the excess of the vane length over the rotor diameter, 0 is the angle between a line joining the center of the rotor and an end of the arc of smaller radius and a line joining the center of the rotor and the point on the curve whose position is to be determined, K is a constant whose value varies from 0 to 0.200, both inclusive, and m is an exponent Whose value varies from /2 to 2.

wherein 0 is the angle between a line joining the center or the rotor and an end of the arc of smaller radius and a line joining the center of the rotor and the point on the curve whose position is to be determined, and a is the angle subtended by said arc.

7. A pump of the sliding vane type comprisin 7 a body having a cavity therein, a rotor rotatably mounted in said cavity eccentrically thereof; said cavity having a cross-section defined by two opposite concentric arcs of unequal radii, and vane extending and retracting curves joining adjacent ends of said arcs, said curves being generated curves determined by the equation wherein R is the distance from the center of the rotor 'to the point on the curve whose position is to be determined, 11 is the radius of the rotor plus running clearance, 71. is the excess of the vane length over the rotor diameter, a is the angle between a line joining the center of the rotor and an end of the arc of smaller radius and a line joining the center of the rotor and 1 tracting curves, joining adjacent ends of said arcs, said curves being generated curves determined by the equation 5. In a rotary pump of the sliding vane type,

a rotor, a pump body having a stator therein. said stator having an internal cross-section defined by two opposite concentric arcs of unequal radii, and vane extending and retracting curves joining adjacent ends of said arcs, said curves being generated curves determined by the equa-- tion R=r1-l h[sin 0+K sin" (40)] wherein R is the distance from the center of the rotor to the point on the curve whose position is to be determined, n is the radius of the rotor plus running clearance, h is the excess of the vane length over the rotor diameter, 0 is the angle between a line joining the center of the rotor and an end of the arc of smaller radius and a. line joining the center of the rotor and the point on the curve whose position is to be determined, K is a constant whose value varies from 0 to .10355, both inclusive, and m is an exponent whose value varies from /2 to 2.

wherein R is the distance from the center of the rotor to the point on the curve whose Position is to be determined, n is the radius of the rotor plus running clearance, h is the excess of the vane length over the rotor diameter, and 0 is the angle determined from the equation wherein R is the distance from the center 01' the rotor to the point on the curve whose position is to be determined, n is the radius or the rotor plus running clearance, 71. is the excess of the vane length over the rotor diameter, 0 is the angle between a line joining the center of the rotor and .an end of the arc'of smaller radius and a line joining the center or the rotor and the point on the curve whose position is to be determined and m is an exponentwhose value varies from /2 to 2.

9. A pump of the sliding vane type comprisin a body having a cavity therein, a rotor rotatably mounted in said cavity eccentrically thereof, said cavity having a cross-section defined by two opposite concentric arcs of unequal radii, and vane extending and retracting curves joining adjacent ends of said arcs, said curves being generated curves determined by the equation R=ri+hlsin 0+K sin (46)] wherein R is the distance from the center of a the rotor to the point on the curve whose position is to be determined, 11 is the radius of the rotor plus running clearance, h is the excess of the vane length over the rotordiameter, 0 is the angle between a line joining the center of the rotor and an end of the arc oi smaller radius and a line joining the center of the rotor and the point on the curve whose position is to be determined, K is a constant whose value varies from 0 to 0.2000, both inclusive, and m is an exponent whose value varies from /2 to 2.

10. A pump of the sliding vane type comprising a body having a cavity therein, a rotor rotatably mounted in said cavity eccentrically thereof,

1 said cavity having a cross-section defined by two opposite concentric arcs of unequal radii. and

vane extending and retracting curves Joining adjacent ends of said arcs, said curves being generated curves determined by the equation =r1+h[sin= o i-K. sin" (40) 1 wherein R is the .distance from the center oi the rotor to the point on the curve whose position is to be determined, n is the radius of the rotor plus running clearance, h is the excess 10 of the vane length over the rotordiameter, a

.is the angle between a line Joining the center ELBERT FOWLER.

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