US2246275A - Rotary pump - Google Patents

Description

n 1941. w. w. DAVIDSON 2,246,275

ROTARfi PUMP Filed July '51, 1936 4 Sheets-Sheet 1 June 17, 1941. w, w. DAVIDSON ROTARY PUMP Filed July 51, 1936 4 Sheets-Sheet 5 r 6 g1 Qww \NN W ww NN 2 4 W m +1 W M 3m Ww \N w mm June 17, 1941. w, w. DAVIDSON 7 ROTARY PUMP Filed July 31, 1936 4 Sheets-Sheet 4 Patented June'17, 194T UNITED STATES PATENT OFFICE ROTARY PUMP I William Ward Davidson, Chicago, 11]. Application July 31, 1936, Serial No. 93,633

3 Claims.

This invention relates to improvements in rotary pumps or compressors of all kinds but particularly to those designed and adapted for use as gas compressors in small refrigerating plants such as are now commonly used in house refrigerators.

A principal object of the invention is to provide a rotary compressor or pump, combined with a motor for operating same, which shall be of the most simple construction and which shall combine in one rotatablesunit the rotatable part of the compressor and'the rotatable part of the motor.

A further object of the invention is to provide a combined compressor and motor in which the overall axial dimension shall be reduced to that required for the compressor.

A further object is to provide a combined compressor and motor arranged in a sealed casing of minimum dimensions and automatic means for continuously oiling the bearings and opposed movable surfaces of the compressor.

The invention includes an electric motor for driving the compressor and having an enlarged rotor within which the compressor is arranged, to be driven thereby, and which construction results in a compressor of minimum height and high efficiency.

The invention also includes the arrangement of the compressor, the rotor of the motor and the statoror field of the motor all in substantially a single plane and preferably in a horizontal plane with the axis of rotation of the compressor arranged vertically.

It should be understood that many of the features of the invention are capable of incorpora-,

tion in assemblies other than compressors, such for instance vacuum or exhaust pumps and pressure pumps for gases, air or liquids and that in the use'of the word compressor it is intended to include all other possible machines other than the preferred embodiment of the invention herein shown and described as a compressor. In other words it should be understood that the invention and its various novel features are not limited merely to compressors for use in refrigerating systems.

To attain the objects and benefits of the invention, a pump or compressor embodying the invention and improvement, comprises the various features, combinations of features and details of construction hereinafter described and claimed.

In the accompanying drawings forming part of this specification, and in which a preferred form of the invention is fully illustrated:

Fig. 1 is a vertical, central section, having parts broken away for more clearly showing the invention and taken on the line |l of Fig. 2;

Fig. 2 is a top plan view of the compressor shown in Fig. 1;

Fig. 3 is a fragmentary, horizontal section on the line 33 of Fig. 1;

Fig. 4 is a vertical, central section or the rotating parts of the compressor and taken substantially on the line 4-4 of Fig. 11;

Fig. 5 is a section similar to Fig. 4; but taken on the line 5-5 of Fig. 10;

Fig. 6 is a bottom perspective view of the upper head of the compressor cylinder;

Fig. 7 is a top perspective view of the compressor rotor;

Fig. 8 is a bottom perspective view of the lower cylinder head of the compressor cylinder;

Figs. 9, 10, 11 and 12 are horizontal sections on the lines 89, lib-l0, lI-ll and l2l2 respectively of Fig. 4;

Fig. 13 is a perspective view of a compressor shaft;

Fig. 14 is a fragmentary section of the lower cylinder head on the line I l-l4 of Fig. 12;

Fig. 15 is a fragmentary'horizontal section on the line l5--I5 of Fig. 1; and

Figs. 16 and 17 are fragmentary vertical sections on the lines l6l6 and l'l-ll respectively of Fig. 15.

The complete compressor, shown in the drawings comprises a rotary compressor A, an electric motor B of peculiar construction and a casing or dome C within which the compressor and motor are enclosed. The casing is circular in horizontal, cross section, the compressor is arranged on a vertical axis located centrally .of the casing and the motor is arranged encircling the compressor andbetween the compressor and the circular wall of the casing. Thisarrangement of the compressor and the motor results in many important advantages and results among which are'; the possible provision of adequately strong and rigid bearings for the compressor located close to the compression cylinder at each side thereof, thus enabling the eliminatlon of any flexure of parts due to the high pressure and forces involved and also the reduction of overall dimensions to a minimum especially as to height as the compressor and the motor are in effect concentric with each other andonly require height suflicien for the compressor.

While the drawings show the compressor as being built with a vertically arranged shaft it should be understood that the invention is notpart of the limited to such construction, it simply means, that at this time it is considered that this form is the preferred form, as it obviously has advantages over a form in which the compressor would be provided with a horizontally disposed shaft.

The compressor A comprises a cylinder 20 arranged on a vertical axis and closed at its upper end by a head 2| having a flat inner surface 22 and secured to the cylinder 20 by bolts 23.

The cylinder is closed at its lower end by a similar head 24 having a like flat inner surface 25 and is secured'in place by bolts 26.

The cylinder has a cylindrical concentric bore 21 extending straight through from end to end and which bore is closed at its ends by the heads 2| and 24.

Within the bore 21 is' arranged a rotor or r tary piston or core 28, which is of equal ength with the cylinder and has flat upper and lower ends 29 and 30 opposed to the flat inner faces of the cylinder heads.

The rotor 28 is mounted on a vertical shaft 3| and is rigidly secured thereon to rotate therewith, by any suitable means, such as a radial set screw 32, see Fig. 4.

The compressor shaft 3| is arranged eccentric to the cylinder 20 and concentric in relation to the rotor 28, as best shown in Fig. 3 and the diameters of the rotor 28 and the cylinder bore 21 are such that the outer cylindrical surface of the rotor is tangential to the cylindrical surface of the boreat one side of the cylinder as shown at 33, Fig. 3, thus providing a crescent shaped space 34 between the rotor and the cylinder and extending from end to end of the cylinder and which constitutes the pumping or compression space of the compressor. The eccentricity is incheated on Figs. 4 and by the two dot and dash center lines shown thereon.

The casing C within which the compressor A and motor B are arranged is made fluid-tight and has a cylindrical side wall 35 closed at, its

, bottom by an integral wall 36 and closed at its top by a removable head 31 secured to a peripheral flange 38 on the wall 35 by bolts 39. A suitable packing 48 is interposed between the flange 38 and head 31 to make the casing pressure-tight. As'shownthe wall 35 is provided with heat-radiating ribs 4| and the head 31 is provided with similar heat-radiating ribs 42 to assist in dispersing the heat produced when the compressor is operating.

Centrally disposed on the lower head 36 and rising within the casing is a bearing member 43 provided with a central bore 44 in which a bearing sleeve-45 of suitable metal, is fixed. I

The lower end 46 of the compressor shaft 3| is mounted for rotation within the bearing sleeve 45. The bearing member 43 is provided with a circular base 41 and the-lower head 36 of the casing is provided with a circular depression 48 concentric with the casing wall 35 and in which the base 41 fits andit is rigidly secured in place by bolts 49. A bearing member 58, similar to the bearing member 43 is arranged in the upper part of the casing and is provided with a vertical bore 5| in axial alignment with the bore 44 of the lower bearing member 43 and within (in a bearing sleeve) which the'upper end 52 of the compressor shaft is mounted for rotating. This bearing will be described more fully hereinafter. The

- two bearing members 43-and 58 serve to rotat- ;ably mount the rotor 28.

cumferential horizontal shoulder 51 on the bearing member 43 and an outer opposed bearing ring 58 and a row of suitable bearing balls 59 interposed between the two rings. The two rings 55 and 58 are provided with ball runways 68 and 6| respectively and the outer ring 58 is supported by the inner ring 55 through the medium of the row of bearing balls 59.

The outer bearing ring 58 is secured concentrically to the lower cylinder head 24 by means of a ring 62 which is Z-shaped in cross section.

This ring has a vertical peripheral flange 63 within which the lower cylinder head 24 is received and doweled and an inner depending vertical sleeve-like part 64 within which the outer bearing ring 58 is received and an inner circumhead 24 is secured rigidly to the Z-shaped ring and rests upon the upper edge of the outer bearing ring 58. The inner flange 65 of the Z-shaped ring prevents the cylinder rising if there should be any tendency to'do so.

The upper ball bearing 54 comprises an inner bearing ring 61, an outer' bearing ring 68 and an interposed ring of bearingballs 69. These rings are secured in place similarly to the rings of the lower ball bearing 53, the inner ring being fitted upon the inner end 18 of the upper bearing member 50 and the outer bearing ring being secured upon the top of the upper cylinder head 2| by a Z-shaped securing ring 1|. The Z-shaped ring 1| is secured upon the cylinder head 2| by the cylinder head bolts 23.

The upper bearing member 50 is secured to and held in place by a horizontal supporting plate 12 which in turn is held concentrically in position by a concentric bore 13 of the casing within which the plate 12 fits, the bearing member fitting within a central shallow depression 14 in the under side of the plate 12 by bolts 15.

As stated before the motor B surrounds the compressor A and as shown, the motor B comprises a laminated inner rotor member 16 within which the cylinder 20 is concentrically arranged and upon which the rotor 16 is rigidly secured, and an outer laminated, concentrically arranged stator 11. The casing is provided with a concentric bore 18 in which the stator 11 is received and is held, in concentric relation with the rotor 16 but rotatably free therefrom as indicated by the airgap 19. Field coils are carried by the stator.

The stator rests upon an inner circumferential horizontal shoulder 8| on the outer wall of the casing and is held firmly down on same by a metal ring 82 which fits within the lower part of the bore 3 above the bore 18 and which is of slightly larger diameter for convenience in assembly. The ring 82 fits tightly in the bore 82 and when pushed down upon the stator is frictionally held in position. The ring 82 is wide enough to rise high enough to receive and support the plate 12 to which the upper bearing member is secured. The plate 12 is doweled to the ring 82 and is secured thereto by bolts 83.

The upper bearing 50 being thus positioned vertically through the medium of the stator 11, the ring 82 and the plate 12 a slight clearance is provided at thevupper edge of the inner ball bearing ring 61 of the upper ball bearing 54 as shown at 84 to eliminate any possibility of the compressor being bound vertically.

The compressor is, as has been explained, freely rotatable upon the lower ball bearing 53 and the horizontal shoulder 55 on the lower bearing member 43.

The lower cylinder head 24 is provided with a central concentric opening 85 which receives a flange 86 formed on the upper end of the bearing sleeve 45, said flange being eccentric of said sleeve equal to the eccentricity of the rotor 28 and cylinder 20 and the sleeve 45 is held against rotation by any suitable means.

Slight clearance is provided between the upper surface of the flange 86 and the opposed surface of the rotor 28 to avoid any possibility of friction at this point.

The upper cylinder head 2I is provided with a central concentric opening 81 just large enough to clear the compressor shaft 3| which is of course eccentric to the cylinder and said opening 81.

Operating electric current is supplied to the motor by connections 88 which enter through the wall of the casing, through insulation tubes and the connections are sealed to prevent the passage of fluids either into or out of the casing past. the connections. It is not thought necessary to illustrate such connections more than to indicate them as shown on Fig. 2. Although an A. C. type of motor is shown, it goes without saying that the invention is not thus limited but that any suitable type of motor can be used within the scope of the appended claims.

The cylinder 20 is driven by the motor B and the compressor rotor 28 is driven by the cylinder 20. For this purposa as best shown in Fig. 11,

a radial vane 89 is provided fixed in the wall of to the eccentric relation of these two parts and there is provided a simple means for preventing leakage past the vane 89 at its inner edge and the rotor.

This means comprises a cylindrical plug 92 fitting in a longitudinal bore 93 arranged near the outer cylindrical surface of the rotor 28 and opening at its outer side into the crescent shaped space 34. The plug 92 is provided with a radial slot 94 in which the inner edge portion of the vane 89 fits and can move radially in and out as the compressor is rotated. This construction provides a flexible driving connection between the cylinder 20 and the rotor 28 and which can readily be made pressure tight in operation.

The cylinder and rotor rotate in the direction of the arrow 95 on Fig. 11. A discharge opening 96 is provided in the lower cylinder head 24 and this opening is at the forward side of the vane 89. The gas to be compressed by the operation of the compressor is delivered to the crescent shaped space 34 through a substantially radial passage 91 in the rotor 28 which connects with a radial passage 98 in the compressor shaft 3|, which in turn connects with a longitudinal passage 99 extended down from the radial passage through the lower end of the shaft. In order not to make the radial passage 99 in the shaft too large this radial passage in the shaft and the rotor may be duplicated, as best shown in Fig. 4.

As shown in Fig. 1, the lower bearing member 43 extends down into a central pocket I00 in the base and the lower end of the shaft 3| projects down into this pocket, the lower end of the shaft being chambered as shown at I01 and the passage 99 enters the chamber IOI at its top. The pocket I00, in the base, is connected by a radial horizontal passage I02 through the metal of the base to a threaded opening I03 to which a supply pipe can be connected when the compressor is used for compressing gases other than free air. The pocket I00 is sealed against the entrance of oil from the lower part of the casing by the base 410i the bearing member 43.

Through the entrance passages 91 entering the compressor behind the vane 89, the gases I fill the space as the cylinder rotates and are compressed and forced out through the discharge opening 96. The discharge opening 96 is controlled by a valve I 04. The lower cylinder head 24 is provided with a shallow recess I05 to contain the valve I04 which as shown comprises a fiat strip of spring metal extending over the opening 96, see Fig. 14, and a second strip I06 of similar metal and the strips clamped to the head 24 by screws I01. The strip I06 is rounded up between its ends so that its free end is yieldingly pressed against the free end of the strip I04. This construction provides a very efficient check valve which effectively prevents the return to the cylinder of any of the expelled gases. The compressed gases are discharged into the casing C and accumulate in'the casing. To permit the escape of the compressed gases from the casing the plate 12 is provided with many openings I08 which permit the gases to escape freely into the space I09 above the plate and beneath the cover 31. At one point the cover 31 is provided with an opening IIO through which the compressed gasses can be discharged for use through any suitable pressure controlling valve which may be adjusted to permit the discharge of the compressed gases at the desired pressure.

Another feature of the invention relates to automobile means of supplying ample lubrication to all of the bearings of the compressor for reducing friction and to all of the opposed movable surfaces to seal such spaces and increase the efliciency of the compressor.

The lower part of the casing provides a storage space-for a supply of oil as shown at III and I provide means operated continuously, while the compressor is operating, for lifting oil from this supply and forcing it to the various points where it is required for lubrication and sealing purposes.

For lifting and forcing the oil I provide an auxiliary pump which comprises an inner extension H2 at one end of the vane 89, best shown in Fig. 4, which is the operating vane of the auxiliary pump. This auxiliary vane extends radially inward into a crescent shaped space II3 formed at the upper end of the rotor 28.

The rotor as shown is provided with a conthe cylinder and the recess H4 is concentric with the rotor and they are so proportioned that the outer surface of the rib H5 is tangential to and in. contact withvthe opposed surface of the recess H4 at one point as shown at H6 Fig. thus forming thecrescent shaped space H3 through which the auxiliary vane H2 sweeps as the compressor is rotated.

To feed the oil from the supply H I to this space I provide a passage I I8 which extends longitudinally up through the shaft 3| from a point near its lower end to the height of the auxiliary pump where it is connected to the auxiliary pump space H3 by an upwardly inclined passage H9 extending out through the shaft 3| and the adjacent part of the rotor 28 and ending just beyond the inner wall of said space H3. The lower end of the longitudinal passage I I8 connects with a substantially radial feed passage I20 which connects it with a circumferential groove I2| formed in the outer surface of the shaft 3|.

The oil is fed to this groove |2| and passage I20 from the base of the casing through a passage I22 in the lower bearing member 43 and the bearing sleeve 45 and the inner end of which registerswith the groove |2|. A feed tube I23 connects the feed passage I22 with an oil strainer I24 submerged in the oil body I I I. The oil strainer I24 comprises a tubular ring I24 and to which the feed tube I23 is connected. The ring I24 is provided with many small inlet openings I25 on its inner side and the ring is covered with a fine wire. mesh strainer I6 to prevent any foreignv particles entering the oiling system.

The deliveryof the oil from the auxiliary pump space H3 is mainly through a small opening I21 extending through the. inner wall of the pump space and. adapted to deliver the oil into the space '81 within the rib H5.

The oil is thus delivered into contact with the shaft 3| in the space 81.

The oil also is delivered from the auxiliary pump out between the adjacent end of the rotor and the inner surface of the upper had thus assisting in sealing the compressor space at this point. The oil is further delivered along the surfaces of the parts which form the flexible connection between the cylinder 20 and the rotor 28.

The bearing member 50 has an upward extension I28, the cover 31 being provided with a hollow dome I29 into which the bearing extends. This construction admits of the maximum length of bearing without increasing the height of the compressor. The bearing member 50 is provided with. a bearing sleeve I30 of suitable bearing metal within which the shaft 3| is received and rotates. The inner surface of the sleeve is provided with a spiral oil groove I3| which opens at its lower end into the space 81 and is open at it supper end to permit the oil to escape into the interior of the pump casing. The oil is thus fed through the whole length of the bearing and the oil that escapes from the upper end of the oil groove |3I flows down around the upper projection I28. The plate 12 is provided with a central opening I32 which forms a pocket I33 surrounding the base of the projection I28 to receive the excess oil and said pocket is provided with a drain hole I34 extending down through the bearing member 50 and directing the excess oil back into the interior of the casing.

The top surface of the. top cylinder head 2| is provided with a shallow recess I35 which extends from the center opening 81 and is large enough in diameter to extend out to the ball bearings 54. The oil is thus delivered to the ball bearing 54 and any surplus oil works through the ball bearings out into the casing.

To direct oil to the lower end of the rotor 28 and to the lower bearing the shaft 3| is provided in its outer surface with a longitudinally extending oil groove I36, the upper end of which extends into the oil space 81 and the lower end of which extends slightly below the lower end of the rotor 28.

For delivering oil to the lower end of the rotor to lubricate the opposed flat surfaces of the rotor 28 and the lower head 24, an inclined oil feed passage I31 (Fig. 11) is provided extending through the body of the rotor the upper end of which connects with the groove I36'and its lower end connectswith a substantially concentric groove I38 formed in the lower flat end 30 of the rotor. Preferably the groove I38 is not a complete circular groove and the oil is delivered to the groove near one end of the groove and, the other end being closed, the pressure under which the oil is delivered causes it to fill the groove and be forced out radially between the opposed flat surfaces of the rotor and the lower head thus not only effectively lubricating these parts but also effectively sea-ling this point against The pocket I40 is connected to an oil feed passage 42 which extends out through the sleeve flange 86 and delivers oil within the recess between the edge of the flange and'the'adjacent surface of the lower cylinder head 24. The excess oil works down between these surfaces to the lower side of the cylinder head which, similar to the upper head, is provided with a shallow recess I43 which extends from the inner recess 85 out to the ball bearing 53, the excess oil es caping through the ball bearing to collect in the bottom of the casing.

The pocket |4| connects with'the upper end of a spiral oil feed groove I44 formed on the inner surface of the bearing sleeve-45. The lower end of the groove I44 connects with a substantially radial oil passage I45 formed in the body of the lowerbearing member 43 and the outer end of which connects with a delivery tube I46 which delivers the excess oil into the base of the casing.

The compressed gases which rae forced past the che'ck valve I04 escape freely through the ball bearing 53 into the interior of the casing and as has been explained through the openings I08 in the top plate 12 into the space I09 andfrom this space through the delivery opening H0.

As the oil is discharged, as has beenexplained, at several points, from the compressor there will naturally be more or less particles of oil floating in the gases within the casingand I,preferably'- provide a large number ofthe openingsv I08 through the top plate 12-mainly to reducethe speed of the gases through. these openings and I provide a fine wire gauze filter I41 secured on the under side ofthe plate 12 and covering said openings to assist in filtering out the oil carried 'by the gases.

The large area of escape thus provided prevents any clogging thereof to prevent the free escape of the gases and so reduces the rate of flow that the oil clings to the screen and drops back into the casing. Furthermore the many holes I08 serve to appreciably reduce the weightof the plate l2. I

From the drawings and the foregoing description it will now be clear that by means of this invention I am enabled to provide a compressor of minimum height, commensurate with the capacity thereof, and one which can be operated efi'iciently practically continuously.

As many modifications of the invention 'will obviously suggest themselves to one skilled in the art I do not limit or confine the invention to the specific details of construction except within thev scope of the appended claims.

Throughout the specification and the appended claims, the term positive displacement pump is used in the sense that it defines a pump which is capable of building up a relatively high head pressure, such for example as a gear pump, a reciprocating pump, a rotatory pump with one or more comprising a. blade rigidly secured to the same member to which the end plates are secured and having a sealed fit with said member and said end plates, said blade having a sliding and rocking engagement with the other member, means for driving the blade through one of the elements rigid therewith to produce a pumping action, bearing supports for the pump members, and for at least one of said pump members on both sides thereof at points farther apart than-the width of the pumping chamber, a. lubricating and gas sealing system associated with the compressor including means adapted to deliver oil to said infinitesimal end clearances in suflicient quantity and at a pressure at least in excess of dome pressure to effectively seal said clearances against gas leakage, said cylindrical member being driven by a rotary motor surrounding the cylindrical member and substantially centered in the center plane of the cylindrical member, the rotor of the motor being carried by the cylindrical member and supported by its bearings.

2. In a compressor, an air-tight dome, pump members within the dome including a rotatable hollow cylindrical member, a core member mounted therein in eccentric tangential relation for rotation about its own center, and end plates rigidly secured to one of said members and having infinitesimally small and clearances with the other to form a pump chamber, means dividing the chamber into intake and discharge sections comprising a blade rigidly secured to the same member to which the end plates are secured and "having a sealed fit with said member and said end plates, said blade having a sliding and rocking v engagement with the other member, means for driving the blade through one of the elements rigid therewith to produce a pumping action, bearing supports for the pump members, and for at least one of said pump members on both sides thereof at points farther apart than the width of the pumping chamber, a lubricating and gas sealing system associated with the compressor including means adapted to deliver oil to said infinitesimal end clearances in sufiicient quantity and at a pressure at least in excess of dome pressure to effectively seal said clearances against gas leakage, said cylindrical member being driven by a rotary motor surrounding the cylindrical member and substantially centered in the center plane of the cylindrical member, the rotor of the motor being carried by the cylindrical member and supported by its bearings, said bearings being of a rolling type.

3. In a compressor, a gas-tight dome, pump members therein including a rotatable hollow cylinder and a rotatable core mounted in eccentric tangential relation thereto, each being rotatable about its own center, end plates closing the space between the members to form a pump chamber, a blade dividing the chamber into intake and discharge sections, the end plates and blade being rigidly secured to one of the members, the end plates having infinitesimal clearances with the other member, and the blade sliding in a rocker in said other member and having at least a portion extending at all times at least to the pivotal axis of the rocker, means for driving the rigid assembly including the end plates and blade and through the blade driving said other member, bearings for one of said members on both sides thereof and bearing means for the other'member restraining it from canting, and

means for sealing and lubricating said infinitesimal clearances including a. secondary pump within the dome and including a secondary cylinder and a secondary core formed between the main coreand an end plate adjacent thereto, with the cylinder formed as a recess in one of said lastnamed members, and the secondary core formed as a boss integral with the other of said lastnamed members, said secondary pump being constructed and arranged to deliver oil to said infinitesimal clearances in sufficient quantity and at a pressure at least in excess of the pump chamber pressure to effectively seal said clearances against gas leakage.

WM. WARD DAVIDSON.

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