US3274944A

US3274944A - Screw vane pump

Info

Publication number: US3274944A
Application number: US491710A
Authority: US
Inventors: Frederick L Parsons
Original assignee: Individual
Current assignee: Individual
Priority date: 1965-09-30
Filing date: 1965-09-30
Publication date: 1966-09-27
Anticipated expiration: 1983-09-27

Description

S CREW VANE PUMP Original Filed March 2, 1965 2 Sheets-Sheet 1 FIGL INVENTOR FREDERICK L. PARSONS HIS AT TOR N EYS pt. 27, 1966 F. L. PARSONS P S CREW VANE PUMP Original Filed March 2, 1965 2 $heets-Sheet 2 L: Q 22 R ,w\w ggg U N I) k Em \m FIGS.

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(0 x Y e INVENTOR 2 m gt FREDERICK LPARSONS United States Patent 3,274,944 SCREW VANE PUMP Frederick L. Parsons, 759 Morningside Road, Ridgevvood, Nd?a Continuation of application Ser. No. 436,534, Mar. 2, 1965. This application Sept. 30, 1965, Ser. No. 491,710 14 Claims. ((Zl. 1tl313tl) This is a continuation of my United States application Serial No. 436,534, filed March 2, 1965.

This invention relates to pumps and compressors, and more particularly, to improvements in pumps of the type combining the functions of a gyrating rotor and a screw type of pump to increase the eficiency and output of such pumps or compressors.

Many attempts have been made in the past to provide a satisfactory pump of the type having a rotor which gyrates in a pump casing and carries a screwlike vane in contact with the inner surface of the pump casing to advance fluid or gases from an inlet to an outlet port by the combined efforts of the gyrating rotor and screw vane. While, in theory, pumps of the type described generally above should operate quietly and efliciently with a minimum of vibration and require a minimum of maintenance and servicing, such pumps have not lived up to expectations. Satisfactory pressures are not developed when such pumps are used as gas compressors and their pumping efliciency is quite low when they are used for pumping liquids. Moreover, rubbing of the screw-like vane and contact of the rotor with the cylinder when fitted for proper contact therewith has caused rapid wear with the result that, in a short time, clearances are left between the rotor and the casing resulting in greatly reduced pump or compressor efficiency.

A further factor in reducing the efliciency of such pumps is the inability to maintain a satisfactory sealing engagement between the screw-like vane, the pump cylinder or casing and the rotor because of tolerance problems, thermal expansion, and related factors, particularly when the pumps are used for developing relatively high pressures. I have found that the vane will lose contact with the cylinder and the rotor under certain conditions allowing the fluid :to escape and back flow.

In accordance with the present invention, pumps of the gy-rating rotor and screw vane type are provided which overcome the disadvantages pointed out above by providing rotor vane structures which maintain tight working engagement with the casing even under high pressures, thereby greatly increasing the pumping efficiency of the pump for liquids and the pressure developed, when the pump is used as a gas compressor, as the case may be.

More particularly, in accordance with the invention, mechanism is provided whereby the rotor of the pump can be accurately positioned with respect to the pump casing so as to maintain rolling line or zero clearance contact therebetween during the operation of the pump without manufacturing the rotor and the casing to close tolerances. Moreover, the screw vane is constructed and arranged so as to oppose loss of its contact with the wall of the casing, and further the screw vane is so constructed as to resiliently eliminate clearance with the grooves in the rotor in which the vane or vanes are received. Moreover, means are provided in the new pump whereby the discharge pressure of the pump may be more closely regulated, also pressures developed within the grooves behind the screw vane can be regulated and controlled, and satisfactory lubrication of the pump can be obtained. In addition, means are provided in the pump whereby pulsa tions developed in fluid passing through the pump can be dissipated to reduce the noise of operation of the pump, thereby rendering it suitable for usage such as, for example, in submarines where quiet operation is essential.

3 ,274,944 Patented Sept. 27, 1966 For a better understanding of the present invention, reference may be had to the accompanying drawings, in which: 1

FIGURE 1 is a view in side elevation and partially broken away of a typical pump embodying the present invention;

FIGURES 2 to 7 are views in cross-section of various forms of vane constructions used in the pump for minimizing leakage around the vanes during the operation of the pump; and

FIGURE 8 is a view partially in side elevation and partially in section of a coupling for closing and sealing the pressure end of the vane to the rotor of the pump.

The pump 19 illustrated in FIGURE 1 is of a double screw type by means of which air or liquid can be supplied from opposite ends of the pump by essentially mirror image pumping elements to a central discharge port 11 in the pump casing 12. FIGURE 1 shows only one of the two sections of the pump, but it will be understood that the other section of the pump shown in full lines at the right hand end of FIGURE 1 is essentially the same except for a reversal of the inclination of the value 13 of the pump.

The pump 10 includes a generally cylindrical casing 12 having heat dissipating vanes extending around it in spaced relation along its length. The casing includes a cylindrical wall or bore 15. The casing 12 may be formed of any suitable type of metal such as steel, aluminum, bronze or the like, as may be required. At each end of the casing 12 is secured a head 16 and 17, the head 16 having a generally annular rim portion 18, a generally disc-like web portion 19, and a concentrically located hub portion 2t} for receiving an anti-friction bearing 21 of the ball, roller, journal or similar type. One or more openings or passages 22 are formed in the head 16 which serve as intake ports for the pump or compressor.

The head 17 is generally similar to the head 16 except that its rim flange 18 is narrower and the dimensions of the hub therein are of somewhat lesser overall length.

Rotatably mounted in the bearing 21 of the hub is a collar 23 which is keyed to a drive shaft 24 extending axially of the casing 12 and which can be coupled to and driven by a suitable power source such as an electric motor, turbine, internal combustion engine, or the like, as may be required. At the right hand end of and fixed to or integral with the collar 23 is an eccentric 25 of generally cylindrical shape having its axis offset with respect to the axis of the shaft 24. Rotatably mounted on and concentric with the eccentric 25 by means of bearing 26 is a sleeve 27 provided with one or more spring pins 28 extending parallel to the axis of the eccentric and engaging in the end of a hollow cylinder 29 forming a part of the gyrating rotor 30 of the pump. Pins 28 are so arranged as to preload the rotor 30 in respect to its rolling contact with the casing, by means of a greater throw of the eccentric 25.

The hollow interior of the cylinder 29 provides space for cooling the interior of the pump.

Fixedly connected to the cylinder 29 is the shell 31 of the rotor which likewise is cylindrical in shape and is provided at its opposite ends with generally helical grooves 32 which converge toward the center of the rotor 31 and toward the discharge port 11 of the pump or compressor. To conserve Weight, the internal surface of the cylinder 31 is relieved as at the grooves 33 between the internal lands 34 in which the grooves 32 are formed. Coolant can be circulated through the grooves 33. The cylinder 29 and the cylinder 31 may be secured together in any suitable Way, as, for example, by means of the tubular connecting pins 35 which also serve another purpose in the pump described hereinafter. Leakage between the cylinders 29 and 31 can be minimized by means of suitable O-rings 36 or similar seals. In the structure thus far described, the provision of the driving spring pins 28 for coupling the rotor 39 to the collar 27 causes the rotor 30 to be biased toward the casing wall so that any inaccuracy in the dimension of the internal bore of the pump casing and the outer surfaces of the rotor are compensated by the spring pressure exerted by the pins 28, thereby assuring essentially leak-tight contact between the casing 15 and the rotor 30.

Mounted in the helical groove 32 at each end of the rotor 30 is a helical vane 37 which is mounted in a novel manner and in itself is novel in structure. While a helical groove 32 and vane 37 of constant pitch are illustrated, the groove and v-ane may be of decreasing pitch toward the middle of the rotor. Both types of vanes will be referred to hereinafter as helical vanes. The form of the vane shown in FIGURES 1 and 2 includes two spaced-apart

helical side plates

38 and 39 having in-turned l-ower flanged

edges

40 and 41, the combined widths of which are slightly less than the width of the helical slot 32 in which they are received. Between the outer edges of the

vane sections

38 and 39 is a screw-like ring 42 which is designed to be slightly larger in diameter than the inside diameter of the wall 15 'of the pump casing so that the helical vane portion 42 bears against the wall 15 and maintains sealing or zero clearance engagement therewith. Inwardly of the ring 42 are a series of small concave-convex springs 43 which tend to force the

vane sections

38 and 39 apart and into zero clearance engagement with the

walls

44 and 45 of the groove 32 in the rotor 30. The gap between the inwardly turned

flanges

40 and 41 at the inner edges of the vane is sea-led and the springs 43 are supported by means of a strip 46 of resilient, rubbery material, such as rubber, neoprene or the like, depending upon the service conditions under which the pump or compressor is to be used. The strip 46 is compressed somewhat so that it too tends to urge the Vane

sections

38 and 39 apart and to eflectively seal the gap at the inner edge of the vane.

Referring back to FIGURE 1, the end of each vane adjacent the outer end of the rotor 30 is connected to the rotor by means of a constant velocity Oldham coupling which assures rotary movement of the vane 37 with the rotor 30 while nevertheless permitting gyration of the rotor around the eccentric 25 relative to the casing and the vane. To that end, the hub 20 of the head 16 is provided with a bearing sleeve 50 on which is received rotatably a collar 51 having at one side thereof an outwardly extending arm 52 which carries a pin 53 extending through the radially extending slot 54 in an intermediate ring 55 and into openings in the

vane side plates

38 and 39 between a pair of the bowed springs 43 therein, thereby positioning one end of the "vane 37 in contact with the inner wall 15 of the casing but allowing relative radial movement between the rotor 30 and the vane 37. The arm 52 and the collar 51 are caused to rotate at constant velocity with the rotor by virtue of a spline connection including diametrically spaced splines and grooves 56 between the ring 55 and the end of the cylinder 31 of the rotor 30 and right angularly related diametrically spaced spline connections 56a (shown in dotted lines) between the ring 55 and the collar 51. The ring 55 being capable of movement in right 'angularly related directions accordingly allows the rotor 30 to gyrate relative to the collar 51 while causing the collar to rotate with the rotor at a constant velocity.

Inasmuch as the rotor 30 is mounted eccentrically, counterbalancing means is provided to dynamically balance the rotor of the pump, including a counterbalance weight 57 connected by means of screws 53 or the like to the outer end of the collar 23 at each end of the shaft. A suitable cover plate 59 encloses the Weight 57 and is secured together with the end plate 16 to the end of the casing 12 by means of threaded studs 60, bolts or the like.

The head 17 and end plate at the opposite end of the compressor can be the same as the head 16 and the cover plate 59 but inasmuch as the shaft is supported in the head 17 at a point remote from the drive end, the head 17 may be made narrower than the head 16. To accommodate the counterbalance weight, the cover plate 61 may be made deeper and of somewhat different shape than the cover plate 59.

With a pump of the type described above and embodying the present invention, rotation of the drive shaft 24 causes the rotor to gyrate and roll progressively around the wall 15 of the casing and at the same time causes the vane or vanes 37 therein to rotate relative to the wall 1 5. Such gyration and rotation progressively forces the liquid or gas, as the case may be, from the inlets at opposite ends of the casing toward the outlet M. So long as intimate contact is maintained between the rotor 30 and the wall 15 of the casing and between the outer edges of the vanes and the wall of the casing and between the vanes and the

walls

44 and 45 of the grooves in the rotor, the pumping or compression is highly eflicient. In the applicants pump, due to the radial and transverse expansibility of the vanes 37, the necessary intimate contact is maintained between the vane or vanes, the casing and the rotor. Also, because of the resilient action of the pins 28 mounting the rotor 30, intimate contact is maintained between the rotor and the wall 15. Such contact, of course, results in wear. To that end, suitable lubrication for the pump must be supplied. In a gas compressor, a lubricant, such as oil, can be introduced at any selected point along the length of the casing, and, for example, oil may be atomized or sprayed in minute quantities by means of a spray nozzle 65 into the intake ports where it is carried by the air into contact with the moving parts of the pump. Any oil or lubricant carried out of the discharge port 11 may be removed from the air by a suitable oil separator.

When pumping liquids, a lubricant ordinarily is not required and so the lubricating system may be omitted in such pum-ps except for bearings 21 and 26 which can be of the grease sealed type requiring only infrequent servicing.

To further minimize leakage in the system such as would be caused by back flow of fluid along the groove 32 radially inwardly of the vane 37, the free inner or pressure end of the vane may be sealed from the rotor in the manner shown in FIGURE 8. In .and spanning the groove 32 in the rotor is a fixed filler plate 66 which is adapted to receive the semi-cylindrical head 67 of an expansible element 68. Another cylindrical head 69 is received in a complementa'l recess or notch in the free end of the vane 37 and has a tongue 70 which is slidably received in the bifurcated arm 71 extending from the head 67. The tongue 70 and the bifurcated arm span the groove 32, and if necessary may be provided with edge seals to prevent or reduce leakage past them.

Any fluid or liquid which is pumped along the bottom of the groove by the relative movements of the rotor and the vane may be bled into the interior of the cylinder 29 by means of a bleeder valve 72, that may be set to maintain any desired pressure in groove 32 as shown in FIGURE 1.

Also, in the event that regulated pressures are desired in the pump, a bleeder valve 73 which can be preset to a desired pressure may be mounted in a radial bore 74 in the cylinder portion 31 in communication with the tubular coupling 35, to allow excess pressure to be vented into the cylinder 29 and thus mingled with the fluid entering through the intake ports 22. In a liquid pump, the valve 73 may be present to about the pressure to be delivered to the pressure port 11 to prevent pressure fluctuations and resulting noise.

It should be noted that the interior of the rotor is in communication with the intake port at each end and thus the fluid flow through the interior of the rotor also is induced by the operation of the pump so that effective cooling of the compressor is afforded. Coolant can be circulated through a coil (not shown) in the relieved portions 33 of the rotor if necessary.

It will be apparent from the foregoing that the apparatus disclosed in FIGURES l, 2 and 8 overcomes the ditficulties encountered in maintaining eflicient operation and developing high pressures in the gyrating rotor and screw vane type of pumps proposed heretofore. Moreover, by the arrangement of the elements in the pump in the manner described, easy access may be had to any part of the pump for inspection or the like merely by removing one or both of the cover plates and the corresponding heads.

It will be understood that other features may be incorporated in the pump or compressor and modifications made therein. Thus, as shown in FIGURE 1, pulsation which might develop in the pump by the discharge of gas or liquid through the discharge port can be dampened by providing in the portion of the rotor 30 adjacent the outlet port, a cavity 75 communicating with the interior of the casing 12 through one or more slots or openings 76 and mounting within the cavity one or more compressible tubes 77 which are inflated at appropriate pressure to dampen pulsations.

The form of vane described above is preferred, but it also is susceptible to modification in the manner shown in FIGURES 3 to 7. Thus, as shown in FIGURE 3, one side plate 78 of the vane 37' is of generally L-shaped cross-section, While the other side plate 79 is of somewhat thicker rectangular cross-section. The vane section 81 is interposed between the outer edges of the

plates

78 and 79 which are forced apart by means of a series of bowed springs 82. The springs are located by means of the resilient sealing ring 83, which rests on the inturned flange '84 on the plate 78 and engages the vane portion 79.

FIGURE 4 shows another form of vane 37 which includes the two

side vane plates

86 and 87 having inturned

inner flanges

88 and 89 against which the sealing strip 90 rests. Bearing against the ring 90 between bowed springs not shown but similar to the springs '82, are a series of coil springs 91 which bear against the wall contacting vane section 92 and against a button or abutment 93 resting on the sealing strip 90. In this form of the invention, the bowed springs force the

vane sections

86 and 87 apart while the coil spring 91 aids in maintaining engagement between the vane portion 92 and the wall of the pump casing.

In FIGURE 5, the vane 37" is composed of five pieces including two wide

helical vane plates

94 and 95, a contacting vane section 96, and a pair of twisted

helical springs

97 and 98 extending lengthwise between the

plates

94 and 95 to force the

vane portions

94 and 95 apart and the vane portion 96 outwardly. A similar twisted helical spring 100 is used as shown in FIGURE 6 to force the vane sections 101 and 102 against the walls of the groove and the rotor and also to urge outwardly a resilient vane strip 103 which may be formed of rubber, neoprene or the like.

Instead of using metallic springs for maintaining the side vane sections in contact with the walls of the grooves in the rotor, as shown in FIGURE 7, a strip of resilient material such as rubber, neoprene or the like, may be interposed between the side vane sections 105 and 106. To position the strip 104, one or both of the vane sections may be provided with a groove 107. The strip 104 also seals the space between the vane sections 105 and 106 against radial inward or outward leakage. It will be understood that all of the several different types of

springs

43, 91 and 104 can be used in a single vane to provide the desired leak-proof seal and zero clearance between the vane, rotor and easing wall.

All of the modified vanes shown in FIGURES 3 to 7 may be secured at their opposite ends with respect to the 6 rotor in the manner of the vanes disclosed in FIGURES 1, 2 and 8.

Other changes in the size, proportions and the like of the pump or compressor can be made without departing from the invention and accordingly, the forms of the invention described above should be considered as illustrative and not as limiting the following claims.

I claim:

1. Pumps, compressors and the like comprising a casing having an internal cylindrical wall, a drive shaft in said casing concentric with said wall, means in said casing supporting said drive shaft for rotation, an eccentric mounted on said shaft for rotation therewith, a cylindrical rotor in said casing of less external diameter than said cylindrical wall, means resiliently mounting said rotor on said eccentric for gyration in said casing and engagement with said wall, said resilient means urging said rotor against said wall, a generally helical groove in the exterior of said rotor, a helical vane fitting in said groove and engaging said wall throughout substantially the entire length of said vane, said groove being deeper than the width of the vane to enable said rotor to move radially relative to said vane, means positioning opposite ends of said vane relative to said rotor to enable said relative radial movement between said vane and rotor, an inlet in said casing adjacent one end of said vane and an outlet in said casing adjacent to the other end of said vane.

2. Pumps, compressors and the like as set forth in claim 1 in which said vane comprises a pair of generally helical side plates disposed in said groove, a generally helical vane member disposed between said side plates and resiliently engaging said wall, and resilient means between said side plate urging them apart into sealing engagement with said groove.

3. Pumps, compressors and the like as set forth in claim 2, comprising a resilient sealing strip between said side plates adjacent to their inner edges, and an inturned flange on the inner edge of at least one of said side plates for retaining said strip between said side plate.

4. Pumps, compressors and the like as set forth in claim 2 in which said resilient means comprises metallic springs.

5. Pumps, compressors and the like as set forth in claim 2 in which said resilient means comprises a plurality of bowed metallic spring plates.

6. Pumps, compressors and the like as set forth in claim 2 in which said resilient means comprises at least one helical transversely twisted metallic spring.

7. Pumps, compressors and the like as set forth in claim 1 in which said rotor is in rolling engagement with said cylindrical wall and said means for positioning said vane relative to said rotor comprises a constant velocity coupling for rotating said vane with said rotor and enabling radial movement of said rotor relative to said vane.

8. Pumps, compressors and the like as set forth in claim 7 comprising a slidable coupling connected to the other end of said vane and said rotor and disposed in and substantially sealing said groove adjacent to said other end of said vane.

9. Pumps, compressors and the like as set forth in claim 1 comprising compressible pulsation absorbing means in said casing adjacent to said outlet port.

10. Pumps, compressors and the like as set forth in claim 1 comprising means on said drive shaft for counterbalancing said rotor.

11. Pumps, compressors and the like as set forth in claim 1 comprising means for introducing a. lubricant into said intake port to lubricate said cylindrical wall, rotor and vane.

12. Pumps, compressors and the like as set forth in claim 1 in which said rotor is hollow and has an opening in at least one end thereof, and comprising pressure relief means in said rotor extending from the exterior of said rotor to its interior adjacent to said outlet port for regulating the pressure between said rotor, vane and wall adjacent to sald outlet port.

13. Pumps, compressors and the like as set forth in claim 1 in which said rotor is hollow and has an opening in at least one end thereof and comprising vent means in the bottom of the groove in said rotor to the interior of said rotor to vent fluid from said groove inwardly of said vane.

14. Pumps, compressors and the like as set forth in claim 1 in which said rotor is hollow and has an opening in at least one end thereof and comprising vent means in the bottom of the groove in said rotor to the interior of said rotor to vent fluid from said groove inwardly of said vane and comprising pressure regulating means in said rotor extending from the exterior of said rotor to its interior adjacent to said outlet port for regulating the exsaid outlet port.

References Cited by the Examiner FOREIGN PATENTS 12/1924 Great Britain. 5/1936 Great Britain.

MARK NEWMAN, Primary Examiner.

cess pressure between said rotor, vane and Wall adjacent 15 W. J. GOODLIN, Assistant Examiner.

Claims

1. PUMPS, COMPRESSORS AND THE LIKE COMPRISING A CASING HAVING AN INTERNAL CYLINDRICAL WALL, A DRIVE SHAFT IN SAID CASING CONCENTRIC WITH SAID WALL, MEANS IN SAID CASING SUPPORTING SAID DRIVE SHAFT FOR ROTATION, AN ECCENTRIC MOUNTED ON SAID SHAFT FOR ROTATION THEREWITH, A CYLINDRICAL ROTOR IN SAID CASING OF LESS EXTERNAL DIAMETER THAN SAID CYLINDRICAL WALL, MEANS RESILIENTLY MOUNTING SAID ROTOR ON SAID ECCENTRIC FOR GYRATION IN SAID CASING SAID ENGAGEMENT WITH SAID WALL, SAID RESILIENT MEAND URGING SAID ROTOR AGAINST SAID WALL, A GENERALLY HELICAL GROOVE IN THE EXTERIOR OF SAID ROTOR, A HELICAL VANE FITTING IN SAID GROOVE AND ENGAGING SAID WALL THROUGHOUT SUBSTANTIALLY THE ENTIRE LENGTH OF SAID VANE, SAID GROOVE BEING DEEPER THAN THE WIDTH OF THE VANE TO ENABLE SAID ROTOR TO MOVE RADIALLY RELATIVE TO SAID VANE, MEANS POSITIONING OPPOSITE ENDS OF SAID VANE RELATIVE TO SAID ROTOR TO ENABLE SAID RELATIVE