US2908225A - Rotor pump - Google Patents

Description

Oct. 13, 1959 v s. K. LEHMAN 2,908,225

I ROTOR'PUMP Filed June 10, 1957 '2 SheetS -Sheet 1 Jamaal E Lalrman Qct.13,195'9 s. K. LE MAN 2,90 ,225

I ROTOR" PUMP 2 Sheets-Sheet 2 Filed June.10, 1957 A a r Patented Oct. 13, 1959 ROTOR PUMP Samuel K. Lehman, Brooklyn, N.Y., assignor to C. H. Wheeler Manufacturing Company, Philadelphia, Pa., a corporation of Pennsylvania Application June 10, 1957, Serial No. 664,558

2 Claims. (Cl. 103-124) This invention relates to pumps of the type having a rotor eccentrically mounted for rotation within a cylindrical chamber. In this type of pump the rotor sweeps along the cylindrical surface of the pump chamber and draws fluid from an intake port as it delivers a previously drawn body of fluid under pressure into a discharge port during each revolution of the rotor. The high and low pressure sides of the rotor are separated by a circular surface of a pivoted segment which continuously cooperates with the rotor to effect a seal. The segment is oscillated by a linkage driven directly from the shaft of the rotor. The shaft on which the sealing segment is mounted is located intermediate the intake and discharge ports of the pump and the linkage is so designed as to cause the segment to rapidly advance towards the intake port as the rotor approaches and passes the end of a compressing stroke and to be rapidly retracted from the intake port shortly after the discharge delivery has taken place.

A feature of the present invention resides in the utili, zation of the sealing segment for closing the intake port between compressing or delivery strokes. This is accomplished by forming a circular surface within the intake port at a predetermined location for cooperating with the moving free end of the segment for effecting a seal closing off the intake port as the rotor rotates a distance corresponding to its movement between the end of a discharging delivery and the beginning of the discharging delivery of the next succeeding cycle. The circular sealing surface of the intake port is located at a distance outwardly from the intersection of the intake port with the circumference of the pump chamber. Owing to this arrangement the intake port is maintained closed from the time a body of compressed fluid is discharged from the pump chamber until the rotor has turned sufiiciently to initiate suction on the intake port, at which moment the segment is moving rapidly toward a fully opened position.

Another feature of the invention is the manner in which the segment which seals between the high and low pressure sides of the rotor and also temporarily closes the intake port is mounted upon the shaft by which it is oscillated.

Still another feature of the invention is concerned with the construction of the pump whereby the shaft on which the combined intake valve and rotor seal is mounted is located across the discharge port and close to the pump chamber in the interest of effecting economy in construction and operating efliciency.

Although the novel features which are believed to be characteristic of this invention be particularly pointed out in the claims appended hereto, the invention itself, as to its objects and advantages, and the manner 2 in which it may be carried out, may be better understood by referring to the following description taken in connection with the accompanying drawing forming a part hereof, in which:

Fig. 1 is a side view of a pump embodying the invention and showing parts of the pump body and rotor broken away;

Fig. 2 is a cross-section of the pump taken generally on line 2-2 of Fig. 1;

Figs. 3 and 4 show various positions of the sealing segment for different rotary positions of the rotor.

The pump body 11) includes a central casting 11 enclosing a cylindrical chamber 12, an intake port '13 and discharge ports 14 and 15, opening into the cylindrical chamber. The central member 11 and the cylindrical chamber 12 are closed at one end by a front head 16 and at its other end by a rear head 17 which are pinned or otherwise fastened to the central member by bolts (not shown). The central member is also cored for a discharge passage 18 and for a chamber 19 through which water may be circulated for controlling the temperature of the pump.

Each discharge port is provided with a check valve 29 adapted to be resiliently pressed onto its seat 21 by a spring 22 supported from a plate 23. Each plate 23 is mounted on a plurality of posts 24 extending upwardly from a platform 25'. The check valves prevent back flow from the passage 13 to the dischargeports 14, 15. The invention is shown in the drawing as employed in a dry vacuum pump, but it will be understood that it is suitable for use in conjunction with pumps of like const'ruction for pumping and transferring liquids under conditions which do not require the use of check valves in the deliveryconduits.

The central member 11 has a smooth bore at 26 to provide a close running lit for a shaft 27 which carries a circular sealing segment 28. The segment 28 extends between the inner wall surfaces of the front and rear heads 16 and 17 and is secured in position on the shaft 27 by a plurality of pins 29 and bolts 30. A segment of the bore 26 overlaps the circumference of the cylin drical wall of the chamber 12, and one side of the shaft 27 is finished with a curvilinear surface 32 whereby clearance is afforded for the rotation of the eccentrically mounted rotor 3-3. With this arrangement it is possible to locate the shaft 27 close to the rotor and thereby gain in operating efficiency.

As best seen in Fig. 1, the ends of the shaft 27 eX- tend into the front and rear heads 16 and 17. The heads contain sealing glands for the shaft and provide housings for the bearings 35 and 36. Bearing 35 is spaced from a shoulder 37 by a sealing gland 38 of a suitable composition, such as a carbon-graphite sleeve having an outer circumferential groove 39 and radial openings 40 for providing oil to the front end of the shaft 27. A similar sealing gland 41 is similarly located between the roller bearing 36 and the shoulder 42 adjacent the rear end of the shaft.

The rotor 33 is eccentrically mounted on a shaft 44 whose axis coincides with the axis of the cylindrical chamber 12. The rotor 33 has flat end walls in sliding engagement with the ends walls 45 and 46 of the cylindrical chamber 12. The rotor shaft 44 is mounted in bearings within the bearing housings 47 and 48 of the front and rear heads of the pump body. These bearings are similar to the bearings 35 and 36, and the respective ends of the rotor are sealed by sealing glands on the rotor shaft similar to the glands 38 and 41.

A gear 50 is fastened to the rear end of the rotor shaft 44 and meshes with a gear 51 fixed to a shaft 52 of an oil pump 53. The oil pump is mounted in a crankcase 54 which is removably secured to the rear head 17. The lower portion of the rear head and of the crankcase serves as a sump which receives oil drain-- the invention is utilized in a pump for pumping liquids or gases the sealing glands are replaced with standard shaft seals, the sump pump is eliminated and the bearings are lubricated by conventional methods.

The shaft 27 is driven to oscillate once for each revolution of the rotor 33. The drive is accomplished through a crank 60 splined'to the rotor shaft 44, a crank 61 splined to the shaft 27 and a, link 62 pivotally connected with each of the cranks.

The outer surface 63 of the segment 28 is in the form of a circular are having a center coinciding with the pivot center between the crank 61 and the link 62, and the radius of the circular surface 63 is such that it will always be tangent to the outer cylindrical surface of the rotor 33 as the rotor rotates. For any rotational position of the rotor, the line of tangency between the circular surface 63 and the rotor 33 is on the center line 64 of the link 62. Owing to this construction of linkage, as the rotor rotates the line of tangency and hence the sealing area between the high and lowpressure sides of the rotor shifts along the circular surface 63. This is demonstrated in Figs. 2, 3 and 4 in which different positions of the rotor and of the oscillatory shaft and segment 28 are illustrated.

The rotor is ilustrated in Figs. 2 and 4 in different positions approximately 180- apart. In Fig. 2 the segment 28 is in its most inward position with respect to the intake port 13, and in Fig. 4 the segment 28 is in its most retracted position or in the position in which the passage from the intake port to the circular chamber 12 is open to its maximum extent.

The rotor is rotating counterclockwise as viewed in Flgs. 2, 3 and 4. As the rotor advances to the position shown in Fig. 3, one side of the rotor delivers fiuid to the discharge port 14 under pressure and the trailing or low pressure side of the rotor draws fluid from the intake port 13. When the line of tangency 66 of the rotor with the cylindrical bore of the pump chamber 12 advances into the discharge port 14, there would be clear passage around the rotor between the intake port and the discharge port but for the sealing off of the intake port by the free end .67 of the segment 28 and the circular surface 68 Within the mouth of the intake port 13. The curvature of the circular surface 68 is that of a circle whose center is located on the axis of the shaft 27 and its radius is substantially equal to the radius of the extreme end of the segment 28.

One edge of the circular surface 68 is in the form t" of a shoulder 69 spaced outwardly from the intersection of the intake port with the circumference of the pump chamber 12 at such a distance as to effect closure of i the intake port when the rotor has completed its discharging delivery. The breadth of the circular surface the segment 28 is just leaving the circular surface 68 to effect initiation of suction at the intake port 13 as the rotor continues to rotate. During the intervening period since the completion of the preceding discharge delivery, the link 64 has moved to the position 64a and the free end 67 of the segment 28 has moved to the position illustrated in Fig. 2 and back to the position illustrated in Fig. 3 and has thereby maintained the inlet port 13 closed from communication with the pump chamber.

The enlargement of the mouth of the intake port at '70 provides for immediate suction on the intake port as the free end of the segment 28 leaves the circular surface 68.

In addition to the dual scaling functions of the segment 68, the arrangement of parts is such that a smaller rotor may be used for a given size pumping chamber whereby to provide a maximum pumping capacity per revolution of the rotor. The pump body, rotor and sealing segment may be made of mild steel or of any other suitable material such as aluminum, for example. When the pump is used as a dry vacuum pump oil is introduced to the intake in small quantities to assure sealing between the cooperating surfaces of the rotor and sealing segment, but this is unnecessary when the invention is utilized in a pump for pumping liquids.

The application and use of the invention will be apparent to those skilled in the art in view of the foregoing disclosure. While an apparatus has been described which is presently considered to represent the best mode of carrying out the invention, it is to be understood that various features and elements in the combinations and relationships involved may be altered and others omitted without departing from the scope of the invention privileged by the appended claims.

What is claimed is:

1. A pump comprising a body member having a cylindrical pump chamber, end heads at either end of said body member and providing walls for closing the ends of said pump chamber, a circular rotor eccentrically mounted on a shaft journalled in said end heads for rotation on the radial center of said pump chamber and in sweeping relationship to the interior cylindrical surface of said pump chamber, said body member having a bore parallel to said pump chamber with the circular wall of the bore intersecting the cylindrical surface of said pump chamber, intake and discharge ports disposed adjacent one another and respectively communicable with said bore at opposite sides of said bore, an oscillatory shaft in said bore, said oscillatory shaft extending into said end heads, bearing means mounted on said end heads for mounting said oscillatory shaft, said oscillatory shaft having an outer circular surface providing a running in with the circular wall of said bore whereby direct communication between said intake and discharge ports exteriorly of said oscillatory shaft and interiorly of said bore is restrained, said oscillatory shaft also having a radially reduced portion which allows said rotor to pass said oscillatory shaft as the rotor moves between said discharge port and said intake port following the completion of a discharging stroke of the rotor, means for oscillating said oscillatory shaft, said shaft-oscillating means including a crank on said rotor shaft, a crank on said oscil latory shaft and a link pivotally connected to each of said cranks, a valve extending longitudinally and laterally of said oscillatory shaft and attached thereto, said valve having an outer convex surface facing said rotor withits center of curvature located at the center of pivot between said link and said crank on said oscillatory shaft, said convex surfacerof said valve providing a sliding seal between said valve and said rotor continuously separating the .high and low pressure sides of said rotor as saidrotor rotates and said oscillatory shaft and said valve oscillate, said valve moving from said pump cylinder into said intake port and from said'intake port into said pump chamber as said rotor rotates, a segmental concave surface in the wall of said intake port LU" In.

opposite from said oscillatory shaft and over and along which the free end of said valve sweeps to effect closure of said intake port against communication with said pump chamber during a portion only of the distance of travel of the free end of said valve within said intake port and while the generatrix of maximum eccentricity of the rotor travels past the discharge port, the oscillatory shaft and the intake port, the longitudinal edge of said segmental concave surface nearest the pump chamber being spaced radially outwardly from the circumference of the cylindrical surface of said pump chamber at a distance to effect said closure of the intake port while said valve moves outwardly along the intake port, and reverses and moves inwardly towards said pump chamber to open communication between said intake port and said pump chamber before the free end of said valve leaves said intake port at the intersection of said intake port with the cylindrical surface of said pump chamber.

6 2. The combination set forth in claim 1 in which said valve has a mounting portion extending within the circular area of the bore containing said oscillatory shaft, said mounting portion removably mounted to an exterior surface of said oscillatory shaft disposed Within the diameter of the outer circular surface of said oscillatory shaft.

References Cited in the file of this patent UNITED STATES PATENTS 663,184 Morris -1 Dec. 4, 1900 922,189 Pratt May 18, 1909 2,796,030 Nebel June 18,- 1957 FOREIGN PATENTS 6,431 Germany of 1878 600,383 Great Britain Apr. 7, 1948 641,390 Great Britain Aug. 9, 1950

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