US2101051A - Rotary fluid displacement device - Google Patents

Description

Dec. 7, 1937. E. A. CUNY 2,101,051

ROTARY FLUID DISPLACEMENT DEVICE Filed July 20, 1935 2 Sheets-Sheet-l J MENTOR.

ATTORNEY.

Dec. 7, 1937. E. A. CUNY ROTARY FLUID DISPLACEMENT DEVICE Filed July 20, 1935 2 Sheets-Sheet 2 INVENTOR.

ATTORNEY.

FIE/l- Pate ted De 7,1931

PATENT OFFICE- ROTARY FLUID D ISPLACEMENT DEVICE Ernest Alexander Cnny, New York, N. Y., auignor to Cunward, Inc., Brooklyn,

' tion of New York N. Y., a corpora- Appllcatlon July 20, 1935, 'Serial No. 32,371

- 12 Claims.

, This invention relates to rotary fluid displacement devices. I

It is desirable in compressing, delivering, or exhausting gases,,in pumping-liquids or in creating and maintaining vacuums, that a machine producing these results be of the'positive-acting rotary type, simple and economical in construction with a minimumof moving parts, relatively free from friction, noise and wear, emcient in operation over a wide range of rotational speeds, and adapted to be direct-connected to a motor or other power drive source at the operating speed of'the latter without the need of intermediate speed reductionmeans.

. 16 A considerable number of designs have been proposed for such rotary compressors, pumps'and thelike, but none have met with any degree of success due principally to the fact that when they are operated at even moderate speeds the fric- 20 tion developed causes excessive heating and;for

this reason they are usually required to ,be run in oil and are accordingly limitedto those applications where the use of oil is not objectionable, z The friction further causes excessive heating of 5 thexcompressed gas with resultant lowering of the efiiciency of the machine due to drop in pressure of the compressed gas as itsheat is dissipated after it is discharged from the machine.

My invention overcomes these objections and ohso tains all the above mentioned desirable results.

A preferred embodiment of this invention comprises essentially two obliquely disposed shafts, one carrying a slotted conical disc and the other carrying a fiat disc with integral blades perpendicularly disposed thereon and engaging said slots in the first mentioned disc, all being housed within a casing having a substantially spherical circumference with discharge ports therethrough, and sides shaped substantially similar to the 40 respective rotating discs and having suction ports therethrough, such that rotation of the elements within-the casing causes alternate compression l and expansion ofthe chambers defined by the oscillating blades, disc faces and easing, thereby resultingjin suction and compression of the fluid therewithin. It further provides a second or additional stage of compression, obtained by extending the blade ends through the conic disc slots to positions proximate to a fixed conic 5 surface formed within the casing, this additional stage'beingoperable in series, parallel or independently of the first mentioned stage,

The present. invention is acontinuation in part and comprises improvements upon the devicedisclosed in my co-pen'ding application Serial No. 19,191, filed May 1st, 1935 more particularly with respect to the blade disposition and the relatlve porting and bathing in--devices oi this type.

It has for its object to provide a positive-acting rotary machine capable of use either as a gas compressor or blower, liquid delivery or a vacuum pump, fluid meter or a like fluid displacement 1 device which is simple and economical of construction and with a minimum number of readily accessible parts. It is a further object to proin vide a machine oi',the type described. which will be' relatively. devoid of friction, noise and wearing of parts, and which will be efilcient in operation over a relatively wide range of rotational speeds, and operable at the relatively'"h igh speeds of the driving motor or other source of power to which. it may preferably be direct-connected without the necessity of intermediate speed reduction means.

Itis also an object to provide sues a-maso;

chine which'requires relatively low starting torque when put into operation against a relatively high pressure on its discharge end or a comparatively low pressure on its-suction end, and a machine which is flexible of arrangement and readily as adapted to multi-stage operation both in series relationship for increase in discharge or suction pressures and in parallel relationship'for increases in discharge orsuction volumes. It

is afurther object toprovide a device of this 30 nature, :whichls self-epriming when used asa liquid pump, and also to be capable of rotation in either direction.

'It is also an object to provide a device of this nature having but two rotating elements within a fixed casing and to furtherprovide such a device having a second stage of compression between one of the rotating-elements and the said fixed casing. It is also an object to provide such a device having a relatively high volumetric efii- 4 ciency.

The present invention is an improvement over my copending application, above referred to, in that the device is improved and simplified by the provision of straight radial blades perpendicu- 45 larly disposed upon the fiat disc element which has an axis of comparatively lesser obliquity with that of the conoidal rotor, resulting in reduced offset and wear of the interconnecting universal joint and lesser clearances and leakage between 5 the blades and slots. It also provides sealing ring construction separating lubrication from fluid spaces and reduces contact surfaces'of rotating parts with the fixed casing thereby further reducing friction and permitting higher rotational 55 speeds. It provides an improved locationof sue tion ports such that centrifugal force assists in both suction and discharge of fluid. It further provides bafiie portions attached to blades such that expanding compartments are prevented from taking compressed fluid from either the discharge line or compressing compartments.

Other objects and advantages of this invention will be apparent to one versed in the art in the course of the following description; all of which is understood to be within the scope of this invention and as more clearly enumerated in the subtended claims.

In the accompanying drawings, forming a part of this description, and inwhich like numerals are employed to designate like or similar parts throughout the same,

Fig. 1 is a plan, cross-sectional in part, of a fluid displacement machine embodying this invention;

Fig. 2 is a side elevation of the bladed element, partly cross-sectional, as taken along the lines 2-2 of Fig. 3;

Fig. 3 is an end elevation of the same;

Fig. 4 is an end elevation of the slotted element; and

Fig. 5 is a partly cross-sectional side view of the same as taken along the lines 5-! of Fig. 4.

Referring to Fig. 1, the fluid displacement machine comprises essentially two rotating disc elements, 3 and 4, keyed or otherwise fixedly mounted upon their respective shafts 8 and I and adapted to be driven simultaneously and at the same speed within a fixed casing, comprising the two casing portions 13 and it. Disc 3 is circular in shape, as more clearly shown in Fig. 3 and has a fiat working surface 41?, exposed to the fluid which lies in a plane perpendicular to the axis Z-Z of the shaft 1 to which the disc is attached. Disc 3 is substantially conical in shape as shown in Fig. 5, and has a conical working surface 3F exposed to the fluid, and opposedly positioned with respect to the corresponding surface 4F of disc 4, which working surface 3F of disc 3 forms a frustum portion of a conical surface having an axis X-X corresponding to that:

of its attached shaft 0, the apex of the said eehe coinciding with the said. extended axis x-x of shaft 8 at a point 0 where the extended axis Z-Z of the obliquely disposed shaft 1 preferably intersects that of shaft 8. This point of axes intersection 0 preferably forms the normal center of rotation of the universal Joint IA-3A, or other flexible coupling means connecting the obliquely disposed shafts I and 3 and causing them to rotate in unison when either is driven 1 from any suitable power source outside the casing, and which is too well known to those acquainted with the art to be further described. Shaft 3 is journalled in a thrust type rollerbearing 6 mounted in the casing I3, and shaft 1 is similarly journalled in a similar bearing 3 mount; ed in the opposite hub end of the casing l3.

The inner surface of the casing l3 designated by MS exposed to the fluid, and more specifically that portion of the inner surface within which the periphery or edge of disc 3 is caused to rotate, forms a spherical surface the center of which is the center point 0 above referred to. The angle formed by the 'axes of the shafts I and 8, which is determined by the angularity of the conical disc 3, or vice versa. preferably causes the working surfaces 31' and F of both discs to be substantially parallel along one of their lat- .erally extending radial center lines parallel and 4 casing are provided with annular sealing rings "A and A which tend to prevent admixture of the bearing lubricant with the fluid being handled in the device.

Due also to the oblique. relationship, of the shafts 1 and 3, the oppositely extending porrtion of the working face 41'' of the flat disc 4 is a comparatively greater distance from the opposed portion of the like face 31" of the conic disc 3 than it is at the degree opposed portions, and forms a comparatively open angle instead of being parallel, resulting in the space ll being other words considerably greater in area than the diametrically opposite space l3, and similarly the volumes of the spaces sorepresented likewise vary considerably.

The fiat bladeddisc l is provided with a cylindrical hub portion 3C and a spherical hub surface 48 which has point as its center and is concentric with the similarly spherical surface 38 of disc 3 with which itis adapted to form a ball and socket Joint.

The disc 4 is further provided with a plurality of blades 4A extending perpendicularly from its working face 41'' and radially disposed with respect to center point 23 and the spherical portion of the hub 48 thereof, and equally spacedfrom each other. The outer or tip portion of these blades have spherical surfaces conforming to the cross-sectional outlines of the inner face I48 of the casing portion it having also point 23 for their center. The inner ends of these blades A terminate in the hollow spherical hub portion 35, which is further adapted to form the ball portion of a ball and socket joint. of which the hub portion 38 of the conicdisc forms the female or socket portion. 'lhis ball and socket joint 43-38 forms a housing for the universal coupling IA-3A which connects the obliquely opposed ends of shafts I and 3 and is adapted to prevent leakage of the compressed fluid into the housing, or to prevent the oil or grease with which the coupling IA-3A may be lubricated from escaping into the fluid spaces indicated by 13 and H, in addition to forming a contact surface over which the two discs oscillate with respect to each other. Both discs are also provided with hub portions IC and 30 which are. keyed in a suitable manner. to their respective coupling halves and shafts=1 and I iournalled within the hub portions of the casing "-14 by bearings 3.

The conic disc 3 has a plurality of slots 3A extending in substantially radial directions from the spherical part of its hub as and-through its entire working face portion from the said-hub to its circumference or periphery. These slots or openings are positioned and dimensioned in width such that the blades 3A are adapted to reciprocate or oscillate therein with a minimum of friction and fluid leakage between the blade and slot surfaces which clearances are determined by the nature or characteristics of the particular fluid which is to be handled, in the'devioe. The variation in the angles at which the blades 3A intersect the surface 31" varies with the angle blade about its rotational axis ZZ of the 'at-' tached shaft I. This angular reciprocation of a given blade within its slot completes ,one cycle, consisting of one opening and one closing move-- ment of the enclosed chamber It, duringone complete revolution of the shafts I and O. The closed, or compressed relationship of the disc faces represented by the space It, and their open position indicated by H, always remain in these relative positions, 180 degrees opposite to each other, and fixed wlthrespect tothe casing II-Id.

In the particular embodiment shown in Fig. 1,

I selected for illustrative purposes only, all rotational torque for turning the flat disc 4 is derived thereby from its attached shaft I, driven through the universal coupling IA-4A from shaft there' being no torque or other rotary forces imposed upon the blades of disc I! by the slotted portion of the disc II in" the embodiment shown. Shaft 8 may be driven from any power source 7 external to the casing l4.

The ends of the casing housing the shafts I and I are' sealed or made tight against leakage due to pressure within the casing by means of suitable stumng box bonnets or end plates 9 and II 'which are additionally provided withsuitable gaskets or spacing rings 2| and are attached to casing II -'-l4 by the usual tap bolts II engaging tapped holes in the hub portions of the casing sections it and I4. The casing halves I3 and I4 arebolted together by means of the tap bolts I2 passing through holes near the circumferences of the casing portions. The casing half I4 is preferably provided with a base portion of any lrnownand suitable type for mounting upon a bed plate or other support (not shown) The casing halves I3-I4 are provided with suction ports IB and discharge ports 2 for supplying and discharging fluids from each stage of the machine, that is, on either side of the rotating conic member 3. An improvement of the present invention lies in the provision of suction ports IA through the sides of the casing halves and relatively nearer to the center of rotation of the compartments whereby centrifugal force due to high rotational speeds and weight of the fluid causes the latter to be carried to the outer portions of the compartments creating both a pressure decrease near the center and a pressure increase at the outer portions which assists in the suction and discharge flows respectively. Openings I are provided through the disc 4 at equal distances from the axis of rotation ZZ such that they aline with and permit intake of fluid through'suctlon ports IA in casing. Obviously the ports IE will be plugged or otherwise closed when this feature of the device is utilized and the fluid drawiri in through ports IA and I.

Bailles' 5 are provided at the periphery of the disc 4 and extend clrcumferentially therewith for a distance which causes the discharge ports 2 in the casing to be intermittently sealed as each compartment enters and passes that position in Iits angular rotation where it would otherwise be open to the discharge line while the adjacent compartment would also be open thereto. Bimiiar bailles IA are attached to the'outer edgesof the blades 4A by means of the fastenings II. The width of the bailles I and IA is slightly less than the clearances indicated by the narrowest widths of the compartments IO and II. The bailles serve to prevent expanding compartments, which have passed the angle of maximum compression, from taking in compressed fluid at a higher pressure from either the discharge line or the following compartment in which the pressure is about to reach its maximum.

The entire rotative assembly is iournalled in the two roller bearings 4 and at no. point other mum clearances are provided between all rotative and non-rotative parts, which clearances are deterinined substantially by the speed of rotation, the size and diameter of the device and the characteristics of the fluid to be compressed. The two rotative elements 3 and 4 comprising the rotative assembly, touch each other only at the spherical surfaces of the ball and socket joint 33-48 and at the halves of the universal joint IA-8A and the respective shafts 1 and 8 to which they are attached. 1

The bearings l are preferably pressure lubricated through fittings (not shown) positioned either in the end plates 0 and III or the adjacent hub portions of the casing. By providing a hollow portion in shaft 1 the universal joint IA-lA and the ball and socket 35-48 can be lubricated from the same source as the outer bearing 6.

In operation, we will flrst consider the compression of thefluid within the single stage portion of the device as defined by the discs 3 and 4 and the blades or partitioning members 4A. Suction and discharge pipes are suitably connected to the threaded ports IA and 2 respectively, connection IB being plugged, and the fluid is led into and fllls the compartment II. This space or compartment I'I formed between the casing surface S and the hub 48, and between the angularly opposed working faces 3! and 41* to rotate in either direction, carrying with it the discs I and 4 connected by the joint lA-8A, the space IT with its enclosed fluid is moved past a point where the port I in the disc 4 will pass beyond the inlet port IA in the casing thereby preventing further passage of fluid into, or from, the compartment I'I.

During the first half revolution the surface 3F moves from its position of maximum angularity with surface 4F, substantially equivalent to twice the angle at which the axes 3-1! and ZZ intersect, or twice the angle ZOX, to the position diametrically opposite indicated by the space I6, wherea radial line on 3F is parallel to the face 4F, and tangent at the line YY. During this 180 degree angular rotation of the moving assembly, the volume of the space H has correspondingly decreased to that of space I6 and the fluid held therewithin between the same to be forced into the discharge pipe, which when the point of greatest compression is passed, is sealed by the bailie 5.

As the rotation continues on the last half of its cycle or complete revolution the compartment gradually increases in volume while the battle I continues to prevent blowbaclr from the discharge, or the following chamber, permitting the residual fluid, which was not discharged, to expand or reduce in pressure until the port I again alines with the suction port IA at which point the pressure within the compartment will be less than the pressure prevailing within the suction,

pipe, thereby causing additional fluid to enter until the two pressures are substantially equal and the passing of the port I again cuts of! the supply to the compartment at which time the cycle is started again. V

In a similar manner the fluid entering the suction port IA and the chamber I8 is compressed between the back or concave side of the disc 3 which also serves as a working face, and the conic surface IlC of the casing portion I4 which latter surface has Z-Z for its axis and is positioned and shaped to provide the proper clearance for the edges of the blades 4A. In this stage of compression, fluid is compressed be-r tween a rotating conic disc and a flxed conic disc, the blades not being fixed to either. A given point on any given blade surface will follow an oscillating or reciprocating path back and forth from the disc slot of its respective blade, or if near the middle of the blade surface it will pass through the slot twice during each revolution. As in the first described stage the fluid is similarly discharged from chamber I! through the port 2.

when both-of the above-mentioned stages are used, compression will be taking place on one side of a given portion of the disc 3 while expansion will be taking place on the opposite side. The suction and discharge ports IA, IB, and 2 have been shown in Fig. 1 within the horizontal plane which passes through both shaft axes, but they can obviously be located either above or below this plane in order to cut 01? the suction or discharge to suit any particular condition of operation or fluid characteristic for which the device may be designed.

When used as a gas compressor at high rotational speeds the clearances between the moving parts may be made suiliciently large to keep friction and heat within reasonable limits, and the leakage due to greater clearances is relatively small due to the comparatively high speed and large output, or delivery.

For use as a liquid pump the angularity of the conic disc 3 and obliquity oi the shafts I and 8 is made comparatively small and the ports are preferably made oval shaped or longer in the direction of rotation and positioned such that the suction and discharge will take place throughout comparatively longer portions of the operating cycle, in order that expansion and compression will be reduced to a minimum. In a modification of this device for such use the conic disc 3 may preferably be replaced by a flat disc similarly slotted to receive the blades of the other flat disc.

As a gas compressor when it is desired to use but one of the two stages the other stage is preferably plugged at its ports and the gas therein will be alternately expanded and contracted with a minimum of expended energy, as the expansion in one compartment assists in the compression in the diametrically opposite compartment. Both stages may be operated in parallel .in the same system or independently in different systerns.

In a modification of my invention the fluid will first be compressed in the stage Il-lt and discharged directly into the suction port IA, or IE, of the second stage I8Il for additional compression. The disc I is preferably shaped and positionedin this modification such that the volume bf chamber I is substantially greater than that of chamber II in order that excessive expansion does not occur in delivering the gas thereto avoiding excessive pressure drop and maintaining a greater overall pressure differential between the suction pressure at port IA of chamber I8 and the final discharge pressure at port 2 of chamber I6.

Obviously a machine comprising any number of such stages as described above could be built within the one casing, and the successive stages connected either in series or parallel depending upon whether greater pressures or volumes are desired.

My invention is not limited to the embodiment shown which has been selected for illustrative purposes only. It may be provided with 3 or more blades and the blade carrying member may be in the form of a conical disc similar to the slotted disc where greater ratios of compression and greater volumetric efficiency is desired. In other modifications both rotating discs may be either flat or plane surfaced; spherical or any,

spheroid of revolution in shape, or any combination of either of these shapes.

In another modification the universal joint may be dispensed with and the rotational torque transmitted from either disc through the blades engaging the disc slots. In still another modification the discs may be driven separately and at the same speeds from opposite sides of the casing.

While I have shown but one of the many possible modifications of my fluid displacement device, it will be understood that the shape and arrangements of the elements may be varied considerably to suit particular conditions, and it is intended that they all be considered as being within the scope and spirit of this invention.

What I claim is:

1. In a fluid displacement device, a rotatable element having radial fixed blades thereon, a casing having a chamber within which the said element is adapted to rotate, the said casing having a conic portion forming a part of said cham-' her and opposed to and having the same axis as the said rotatable element such that the edges of the said blades are adapted to rotate contiguously thereto, a rotatable conic element disposed intermediate the first said element and the said conic casing portion defining two compression stages, the said conic element having radial slots through which the said blades are adapted to reciprocate, the said conic element having a separate axis intersecting the first said axis, inlet and outlet ports in the casing between the said conic portion thereof and the said conic element, inlet ports through the casing and the first said element, and an outlet port between the first said element and the said conic element, and means adapted to rotate the said rotatable elements whereby fluid is caused to be drawn in through the said inlet ports and discharged through the said outlet ports of the respective stages.

2. In a fluid displacement device, a rotatable radially bladed element, a rotatable slotted elearoma! ment to receive the blades oi the said element within its slots, a casing having a spherical chamber within which the said elements are adapted to rotate on oblique axes, suction ports in the said casing and in the said bladed element, discharge ports in the said casing, bailles associatedwith said bladed element adapted to'periodically close said discharge ports,

and means for rotating the said elements such j that compression ,ota fluid-is caused between the said elements slid the said casing and is adapted to be drawn through and discharged from. the

ports thereof.

3. In a fluid displacement device, a rotating in the said casing and said bladed element, an

outlet portJn'the said casing, badles associated with the flrstsaid element adapted to periodically the said outlet port.

close the said outlet port, and flexible coupling means positioned at 1 said axes intersection adapted to cause rotation to be imparted from one of the said elements to the other such that fluid supplied to the said inlet ports is caused to bedlscharged under,.incre ased pressure through 4. In a fluid displacement device, a rotating radially bladed element having a hollow spherical hub, a rotating slotted element adapted to I have the saidblades reciprocate within the slots thereof, the said slotted element having a hollow spherical hub adapted to engage the hub oi the flrst mentioned element, a casing forming a chamber within which the said elements are iournaled and,-adap ted to rotate on separate axes, the said axes intersecting within the chamber, inlet ports in the said bladed element and in the said casing, an outlet-port in the said casing, the said spherical hubs oi the said elements being adapted to form a ball and socket joint about which the said elements are adapted to oscillate,

- bailles associated with the said bladed element adapted to periodically close the outlet ports in the said casing, and flexible coupling means positioned at said axes intersection and within said ball and socket joint, whereby rotation may be transmitted from one of said elements to the other such that when either element is caused to rotate, fluid supplied to the said inlet port is 5 caused to be discharged under increased pressure through the said outlet port.

5; In a fluid displacement device, a rotating disc element having blades radially disposed thereon, a rotating conic element having slots adapted to receive the said blades, a casing having a spherical chamber within which said elements adapted to rotate, suction ports in the said casing and said bladed element, a discharge port in the'sa'ld casing baiiles associated with said bladed element and positioned to serve as closures oi' said discharge port at predetermined points in the rotational cycle, and means for imparting rotation to the said elements. such that fluid enters one of the said ports and is dis charged through another 01 said ports such that the said baiiles prevent the undesired return 01' fluid from said discharge port into the device.

6. A fluid displacement device comprising two elements rotatable about separate intersectingaxes, a casing within which said elements are iournallcd tor rotation, each or said elements having spherical hub portions adapted to iorm a ball and socket ioint, one of the said elements carrying a plurality of blades extending radially irom its hub. portion, the other oi said elements having slots radially disposed with respect to its hub portion, the said blades being adapted to reciprocate-within the said slots upon'rotation oi the said elements, ports in the said casing, bailles associated with the peripheries of the blades adapted to periodically align with the said other, one oi said elements having a plurality of partitioning members extending radially from its hub portion, another oi-said elements having openings radially disposed with respect to its hub portion, the said members being adapted to oscillate within the said openings .upon rotation of the said elements, the saldaxes intersecting at'the center of the said engaged hub portions, suction and discharge ports in the saidfcasing, means associated with the said rotatable ele ments whereby suction and discharge are pree vented during predetermined portions 0! the m tational cycle, and means to impart rotation to one oi the said elements.

8. In a fluid displacement device, elements rotatable about separate oblique axes, a casing within which said elements are journalled' for rotation, each of said elements having hollow spherical hub portions adapted to oscillatably engage each other, one of said elements having a plurality 0! blades extendingradially from its' hub portion, another of said elements having slots radially disposed with respect to its hub portion, the said blades being adapted to oscillate within the said slots upon rotation of the said elements, flexible coupling means connecting the said elements positioned within the said engaged hub portions, ports in the said casing, means associated .with one of the said elements adapted to periodically close the said ports, and

being adapted to rotate in close proximity to the said casing portions, 9. second rotatable element having slots through which the said blades are adapted to reciprocate, the said second element being disposed within the said casing between the said opposed portion thereof and the first said element, the two 'said elements being adapted to rotate on separate intersecting axes, inletand outlet ports in the casing adapted to form a compression stage between the two said elements, inlet ports in the flrst said element adapted to periodically aline with the said inlet port in the casing, inlet and outlet ports in the casing adapted to form a second compression stage between the second said element and the said opposed casing portion, and means to rotate the said elements whereby fluid may be drawn in through the said inlet ports and said outlet ports.

discharged through the 10. In a fluid displacement device, a casing having a chamber defined by spherical and op- I end surfaces thereof, blades carried by the first said element and adapted to rotate in close proximity to the spherical and second end surfaces of said casing chamber and to reciprocate within the said slots, an inlet and an outlet port in the said casing adapted to form a fiuid compression stage between the said elements, inlet ports in the first said element adapted to successively aline with the said inlet port in the, casing, inlet and outlet ports in the casing between the second said element and second said end surfaceadapted to form a second stage, and means to rotate the said elements.

11. In a fluid displacement device, a casing having a chamber defined by spherical and opposed end surfaces, a rotatable element. lournalled for rotation in the said casing remote from one of the said end surfaces, a second element having slots and iournalled for rotation within said casing and being disposed between the first said element and the said remote end surface, the said remote end surface being generated about the extended rotational axis of the first said element, partitioning means extending through the said'slots and adapted to rotate with the said elements about the axis of the first said element and in relatively close relationship with the. said spherical and remote end surfaces of said casing chamber, inlet and outlet ports in the said casing adapted to form fluid-displacement chambers on both sides of the second said element, inlet ports in the first said element adapted to register with one of said casing inlet ports, and means to rotate the said elements.

12. A fiuid displacement device comprising a rotatable element having radial blades, a second rotatable element having slots adapted to receive the said blades, a casing having a chamber within which the peripheral portions of the said elements are adapted to rotate in contiguous relatic'nship, suction ports in the said casing and said bladed element, discharge ports in the said casing, bai'fles associated with one of the said elements-adapted to periodically close the said discharge ports and the suction port in the said casing whereby rotation of the said elements causes fiuid intake through the suction ports and discharge through the said discharge ports, the said baffles preventing undesired return of fiuid from said discharge ports into the said chamber.

ERNEST A. CUNY.

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