US2470987A - Rotary pump stator - Google Patents

Description

Patented May 24, 1949 UNITED ROTARY PUMP STATOR James P. Johnson, Shaker Heights, Ohio Application September 3, 1947, Serial No. 771,887 9 Claims. (01. 103-135) The present invention relates generally as indicated to a rotary pump and more particularly to that'type of pump in which a vane carrying rotor operates in a stator formed with a noncylindrical bore, said vanes having their opposite ends in engagement with the wall of said bore.

It is one of the primary objects of this invention to provide a pump of the above character in which the stator bore is of such unique form that the pump has improved operating characteristics especially with regard to the operating efficiency thereof and the absence of mechanical shock therein.

Other objects and advantages of the invention will appear as the following description proceeds.

To the accomplishment of the foregoing and related ends, said invention then comprises the features hereinafter fully described and particularly pointed out in the claims, the following description and the annexed drawing setting forth in detail certain illustrative embodiments of the invention, these being indicative, however, of but a few of the various ways in which the principle of the invention may be employed.

In the drawing:

Fig. 1 is a transverse sectional view of the rotor and stator portions of the pump constituting the present invention;

Fig. 2 is a diagrammatic representation of the manner in which the stator bore is formed; and

Fig. 3 is a layout of the diagram of Fig. 2 on Cartesian coordinates to more clearly indicate the smooth nature of the stator bore.

Referring now to the drawing, the structure illustrated in Fig. 1 comprises a stator l formed with a bore 2 of generally elliptical form, such bore being intersected by two pairs of diametrically opposed inlet ports 3 and outlet ports 4 which form diametrically opposed partitions 5 therebetween. As shown, the partitions 5 are so arranged that their center lines coincide and pass through the axis of bore 2, thus dividing the bore into two similar and oppositely arranged sections.

Within the bore 2 is a rotor 6 which has a close running fit with the partitions 5 to provide a fluid radius from the pole ll.

from the pole 0 are respectively designated 1' and R. The portion of the curve between points 8 and 8 is a straightiine parallel to the major axis and perpendicular to the minor axis and therefore the radius r. to any point between 8 and 9 is equal to meet), 0 being the angle between the radii r and n.

The portion of the curve between points 9 and III is a section of an Archimedes spiral which is tangent to the aforesaid straight line at the point 9, such spiral section being the path traced by the end of a ray which lengthens with uniform velocity as the ray revolves with uniform angular velocity about "I." In other words, if the angle between the points 9 and II were divided into equal parts, the radius from "8" to the spiral sec-' tion would increase a predetermined amount from one radius to the next succeeding one.

The remaining portion of the curve between points It and II is such. that at point l0 it is tangent to the Archimedes spiral section and at point II it is parallel to theminor axis and perpendicular to the major axis, such curve startin at the point It and decreasing in radius byan amount equal to that which radius r, increases at the portion of the curve between the points! and S. It will be observed that the angle a between points l0 and II is the same as between points 8 and 9. The equation of this last described portion of the curve is R,=R-r(sec0-1) wherein R. is the radius at any angle 0 between the radii R. and R... Although this portion of the curve is preferably made in conformance with the equation, it has been found. that in many instances this curve may be a circular arc of radius X struck from a point l2 along themajor axis of the bore and tangent to the Archimedes spiral at the point Ill, such radius X obviously being less than the Having thus defined the elements of one quarter of the bore. 2, it will now be apparent that with a bore formed by four of such curves arranged as shown, the straight line portions H tight seal therebetween. Rotor 6 carries arcuate will smoothly join one another as will the curved.

by the straight line between the points I and II on Fig. 3 and a gradual deceleration from such constant velocity to zero velocity between the points ill and II. With a bore formed as described. the sum of the radii of the two points on bore 2 contacted with by the two edges of each vane I is a constant and inasmuch as the bore 2 is so formed that for each increment of rotation of the rotor 6 one edge or the vane moves inwardly exactly the same amount that the other edge thereof moves outwardly both edges of each vane Twill at all times be in contact with the wall of bore 2, thus providing an emcient pump capable of delivering maximum volume of fluid at a maximum delivery pressure. -Furthermore, by reason of the unique shape of the bore 2 there is no mechanical shock to contend with whereby the pump may be operated at very high speeds.

A further feature of the bore 2 is that because the surfaces of the partitions ii are flat, there is provided a better seal between the rotor 6 and the bore 2 than could be provided if the bore 2 consisted merely of oppositely arranged Archimedes spiral sections.

A pump constructed as explained above is easy to manufacture, is capable of operating at high speeds and because of the smooth nature of the bore 2 is subject to little wear.

Other modes of applying the principle of the invention may be employed, change being made as regards the details described, provided the features stated in any of the following claims or the equivalent such be employed.

I therefore particularly point out and distinctly claim as my invention:

,1. A stator for a rotary pump formed with a bore of cross-section which in part comprises a curved line constituting a portion of an Archi medes spiral, a straight line tangent to one end of such curved line, and another line tangent to the other end of such curved line.

2. A stator for a rotary pump formed with a bore of cross-section which in part comprises a curved line constituting a portion, of an Archimedes spiral, a straight line tangent to one end of such curved line, and another line tangent to the other end' oi such curved line, such lastmentioned line decreasing in radius with reference to the pole of such curved line and from a point commencing at such other end of the latter by the same amount that the distance from suchpole to such straight line decreases from a point commencing at such one end of such curved line.

3. A stator for a rotary pump formed with a bore of cross-section such that one quadrant thereof successively constitutes straight line, Archimedes spiral, and curved line portions, such straight and curved line portions each being tangent to such spiral portion.

4. A stator for a rotary pump formed with a bore of cross-section such that one quadrant thereof successively constitutes straight line, Archimedes spiral, and curved'line portions, such straight and curved line portions each being tangent to such spiral portion and subtending equal angles with reference to the pole oi. such spiral portion.

5. A stator for a rotary pumpformed with a bore of cross-section as defined by four equally spaced identical but oppositely disposed sections of Archimedes spirals joined by straight line portions tangent to two pairs of adjacent ends of such spiral sections and by curved line portions tangent, to the other two pairs of adjacent ends of such spiral sections.

6. A stator for a rotary pump formed with a bore of cross-section as defined by four equally spaced identical and copolar but oppositely disposed sections of Archimedes spirals joined by straight line portions tangent to two pairs of adjacent ends of such spiral sections and by curved line portions tangent to the other two pairs of adjacent ends of such spiral sections, such straight line portions being bisected by and normal to a line through the common pole of such spiral sections.

7. A stator for a rotary pump formed with a bore of cross-section as defined by four equally spaced identical and copolar but oppositely disposed sections of Archimedes spirals joined by straight line portions tangent to two pairs of adjacent ends of such spiral sections and by curved line portions tangent to the other two pairs of adjacent ends or such spiral sections, such curved line portions at their mid points crossing a line through the common pole of such spiral sections atright angles.

8. A stator for a rotary pump formed with an oblong bore having minor and major axes respectively equal to 2r and 23., one quadrant of such bore including end elements whose radii r. and R9 at an angle 0 from r and R. respectively conform to the equations n =rsec0 and and an intermediate element comprising an Archimedes spiral section tangent to such end elements.

9. A stator for a rotary pump formed with an oblong bore having minor and major axes respectively equal to Zr and 2R, one quadrant of such bore including end elements whose radii rs and R9 at an angle 0 from r and R respectively conform to the equations n =rsec0 and and an intermediate element comprising an Archimedes spiral section tangent to such end elements, the pole of such intermediate element coinciding with the intersection ofsuch minor and major axes.

JAMES P. JOHNSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 872,234 Henry Nov. 26, 1907 2,165,963 Curtis July 11, 1939 2,260,888 Davis Oct. 28, 1941 2,272,635 Davis Feb. 10, 1942 2,347,944 Fowler May 2, 1944 2,352,941 Curtis July 4, 1944 FOREIGN PATENTS Number Country Date 509,953 Great Britain July 4, 1944

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