US2373656A - Rotary operating machine - Google Patents

Description

p i 7, 1945. c. a. BRULL ROTARY OPERATING MACHINE Filed April 3, 1943 3 Sheets-Sheet l m Z P M m n T@ M N mm m VP" T m M s E I m o M Y? C am April 7, 1945. c. B. BRULL ROTARY OPERATING MACHINE 3 Sheets-Sheet 2 Filed April 3, 1945 u u w U S a Tw MN NM R w 3 New CW s IA m a p v MY 65w April 17, 1945. c. B. BRULL 2,373,655

ROTARY OPERATING MACHINE I Filed April 3, 1943 s sheets sheet s INVENTOR. CHARLES B'P/VARD BIPULL A TTORNEYS Patented Apr. 17, 1945 s PATEN fo'rsics- 2,373,655 7 ROTARY OPERATING MACHINE Charles'Bernard'Bi-ull, New York, N. Y.,"assignor to American Prototype Corporation, a corporation of New York I Application April In France 3, 1943, Serial No; 481,699 December, 1 1941 '9 Claims. (Chills-137) The invention refers to rotary operating ma chines. such as rotary pumps or compressors of the kind with single or multiple blades sliding in a shuttle.-

These machines include a stator having a noncir-cular cylindricaljinner surface and a rotor comprising at least one partition, generally called a blade, the planeof which is parallel to; the generatrices of thestator. This partition subdivides the inner, space of the stator into two independent and non-communicating chambers of volumes whichvary during rotation due to "the permanent, contact of the longitudinal edges of the blade with the inner face of the stator; the said movable, and variable chambers assuring the suction. and discharge, and at the same time the transfer of,,the fluid in closed circuit, which condition is very favorable for the preservation of tightness during the continuous angular displacement of the blade in the same direction. The blade is held and guided, during its alternating transverse motion which is necessary to assure its permanent contact with the non-circular Wall of the stator, in a slot provided in a rotary cylindrical support generally called a shuttle. The rotor, therefore,Y-consists of the blade-shuttle assembly. .v V

The purpose of f the invention is primarily 'to design these'machines in such a manner that they can be manufactured byl a simple" machining means, that their volumetric efficiency is improved, that'the 'sealing'between the suction and the discharge isa'ssured under the best conditions and that the friction between the moving parts and at the joints is reduced to a minimum, espe-l cially by a practically complete elimination. of the effects due tocentrifugal' force. It also results from the arrangements described below that there are no complementary accelerations, thus avoiding any parasiticmotions of the blade.

In accordance with the invention the inner surface of the stator of the new machine is in theiform of a conchoid having one retrogression point, namely, a cardioid of a circle. The shuttle comprises a cylinder partiallyembedded in a cylindrical mortise arranged in the lateral wall of the stator in the region of the retrogression point of the 'cardioid. The blade, which reciprocates in a guiding diametric slot in the shuttle, is directly driven and itselt'drives the shuttle.

An important feature of the machine of the invention is the particular location of the suction and discharge :ports of the machine and their width relative to the thickness of the blade which insures maximum, volumetric jefficiency.

Other important features ofthe invention include the ratio of shuttle diameter to blade length and the ratio of blade thickness to blade, length whichratios are such as to insure mechanical stability and maximum efficiency.

A'fu'rther. feature of the invention is the means for insuring tightness along the longitudinal edges of theblade which comprises light gaskets in the form of scrapers capable of sliding transversely with limited amplitude} 4 Other featuresof theinvention will become apparent as the description proceeds.

,Of the accompanying drawings,

Figs. 1' and 2 are diagrams used to facilitate the understanding of the general principle of machine which isthe subject-matter of the invention.

Fig-3, is a viewrepresenting diagrammatically in elevation (partly in section), a pump or a com pressor embodying the principles of the invention explained by the diagrams of Figsgl and 2.

'Fig; 4 is a longitudinal sectional view taken along the line 4-'-4 of Fig. 5 of a compressor made in accordance with the invention.

Fig. 5 .isa transverse sectional view taken along the line'5 -5 "of Fig. 4'; and H Fig. 6 is a diagram illustratingto scale the optimum relative dimensions and. geometrical relations of the various parts of a machine corresponding in, general to the machine of Figs. 4 and 5, but including one feature of the invention shown "in the structure of Fig. 3 but absent from that of Figs. 4 and 5;

' Inaccordance with the invention, and more curves, those constituted by some circular con choidsypossess the peculiarity that the sum of the aligned'radiusvectors'starting from a given point located in the ,plane of the closed curve and inside of same, is constant irrespective of the direction of these vectors." 'j

Among circular conchoids, "those with retrogression' point (Figs. 1, and 2) have, of course,

the above'mentionedpeculiarity, namely that the.

sum :ofthe radius vectors AB and AC or EB and Ecjstartihg from the point A (Fig. 1), or from the arrangements described the point E (Fig. 2) and limited by the curve a or a, remains constant irrespective of the direction of the straight line BC with respect to a fixed reference axis.

In order to facilitate the machining, it is, however, necessary to set aside discontinuous curves formed by arcs of an Archimedes spiral giving rise to an angular point'D (Fig. 1) and to retain only continuous curves without double point, such as circular cardioids (Fig. 2). These curves furthermore have the advantage that when they are used as directrices of a cylindricalsurface which forms the inner face of a container, the volumes of the suction and discharge phases, according to below, are very large for a given occupied space.

In accordance with the invention, the directrix of the cylindrical surface which is to constitute the inner face of the stator of the rotary operating machine (pump, compressor or the like) to be constructed, is given theshape of a cardioid a such asshown in Fig. 2.

At the-placeof thezone in the neighborhood of the retrogress-ion-point (Fig. 2) and in a symmetrical manner with respect to the geometrical axis of the cardioidthere is arranged in the 'wall ofthestator a cylindrical mortise 1 along the arc FGH which therefore removes the entire'material which forms the lunule FEHG.

On each side of the said-mortise, there is arranged, in the wall of the staton'a. symmetrical group of oneor' more ports,such as 2 and 3 which are to serve for the'suction and the discharge respectively ofth'e fluid (liquid or gaseous) which fluid is'intendedtobe drawn inorexpelled by the machine. v

As shown in Fig."3,.'thestat0r is completed by a base' l andbyla'teral covers 5 and 6 suitable to be mounted in 'a' removable manner on' the body I of the stator.

In the cylindrical mortise l the radius and position of which are suchthat the volumes of the suction and discharge phases remain aslarge as possible, there' is, placed .a cylindricalmemberffl of the same diameter, .and which, thus partly engaged in the said mortisejassures a complete contact with the sameIover-the entire surface of this mortise. 'This imbedding of the shuttle in its mortise .hasthe further advantage of reducing the. dead volume 'due to the shuttle.

Th shuttle '8 is terminatedlby a bearing surface 9 which enables it to rest against a bearing l0 of any suitable shape arranged inside of the cover 6 of the stator.

"In'the shuttle, there is arranged a diametral slot- I I .in which there engages with a loose fit a perfectly flat part l2 which constitutes the blade and the dimensions of which are such that its longitudinal edges, corresponding to the points B- and 'C of Fig. 2, are directly or not,.in contact with the inner face of the stator, thus dividing the inner space of the latter into two non-communieating chambers l3 and. It. is known that this contact continues whenthe blade i2 is displaced angula'rly around a suitably selected point (E; on Fig.2). Inasmuch as the portion TFEH of the cardioi'd is eliminated and has been replaced by th shuttle'B, the end of the blade, engaged in the shuttle, ceases'to be in .contact on the FGH side with the wall of the stator when the blade is directed in the neighborhood ofthe axis ofsymmetry of the cardioid'that' is to say, all along the an'gle'FEI-I (Fig.2). However, this has no drawbackbecausefor these positions of .theiblade the tightnessbetween chambers 'l3 and continues shownin Fig. 2, the tightness between the chambers |3.and M is assured by the permanent contact of the longitudinal edges of the shuttle with the inner face of the lateral wall of the stator without any prejudice to the tightness, obtained by suitable devices, between the transverse edges of the shuttle and the covers 5 and 6 of the stator.

Continuoitsiangula'r displacements of the blade l2 around the axis of rotation projected at E, Fig. 2, of shuttle 8 are obtained by having the torque act directly upon .the longitudinal axis of symmetry of the blade l2, the shuttle carried along by the blade then rotating freely in the mortise I, following the motions of the blade. It results from this that the section of theshu-ttle can be reduced to a minimum, whicnfurtherreduces the volume lost due to the shuttle. It can beunderstood that by driving the blade I2 in this manner :by its center (point I 5, Fig. 2), there is obtained a balancing of the stresses which act upontsame and therefore there is-eliminated, on the blade, the effects of centrifugal force :which withany othermannerof drive would manifest themselves by considerable asymmetric'friction between the blade 12 and the inner wallof the stator and between the blade l2 and the edges of the slot H of the shuttle'8. This is particularly what would occur-if the driving of the blade wereefiectedby direct application of the torque on the shuttle.

As indicated in Fig. 3 it is possible toprolong the axis of symmetry of the blade I 2 by means of two round 'tenons f5 and-"I6, the tenon l5 being embedded so as to be able to rotate in a bearing [1 eccentrically carried in'the drive plate 18 which'is integral withthe drive shaft l9, in-such a manner'that'the-path of this tenon is a circle indicated bythe dot and dash line 2-0 (Fig. v2), the center K of which is also the center of the circle which is the generator of the cardioid.

The tenon I6 engages in a fixed 'annillarmortise i6, concentric with .the circular path'traversed by the tenon 'l5,'and corresponding to the arc 'MPN of circle "'20, arranged in the Wall of the cover '6 of the stator. I6 is limited'by the housing of "the shuttle'but the slot ll of the latter is sufiiciently extended on the side where'the tenon f6. is located so'that the latter may slide in the same without any play and thus travel the remaining portion of. its circular trajectory corresponding to the arc NEM of circle 20. The blade [2 is, therefore, guided in all positions by the shuttle '8, by thelateral walls or covers 15 and'G of the stator, by thetenon I5 which is practically embedded in the plate l8, and by the tenon 116 which rests against .the edges of the mortise T6 in thewall '6, when it moves along the .part .o'fits .circular trajectory corresponding to thearc 'MP-N, and against the edgesof the slot II of theshuttle, when it moves along the remaining part of its circular trajectory. The shuttle 8 turns freely around ,its axis in a continuous motion and with constant speed, if the speed of the drive-shaft I9 is constant, "thus cancelling complementary accelerations The shuttle rests against the wall of th mortise l, the bearing [0 and the-adjacent face of the'driving platel8.

In 'thespecial case shown in Figs. 4 and "5, the tenon I6 is omitted and only the "tenon'l5 The annular mortise used. This tenon' I is carried in the bearing ll of thedriving plate 18. Inthis case'the blade,

all along its lateral'ia c'e on the side of the cover 6, is in contact with the'inner face-of this cover 6,- taking 'into -c'onsideration a predetermined clearance which depends, among other things, on the "use of the apparatus. A counterweight I 8 is provided for counter-balancing'the bearing I'IintheplatelB.

A'tig htseal-between chambers l3 and [4, along the longitudinal'edges of the blade, can be assured by arranging; in the said edges; grooves 2| in each oneof which there engages a scraper 22made of a'materialwhich is both resistant and sufliciently plastic as to be deformable, as'for'instance. hard rubber (ebonite) or similar material. 'Eachscraper can slideireely inthe cor responding groove, being guided-by the edges of the'same and'is prevented frombecoming displaced" beyond a certain elongation by holding members such as "pins 23'fas'tened to the-blade tion. They maybe cheaply constructed and are simple to'replace. Being somewhat plastic, their shape willconform to thefsu'rface over which they travel. That is,fafter a'certai'n period of operation their shape willautomatically become exactly what'it should'be to insure a tight seal between the chambers, at all positions'of the blade. "Thus their initial fshape does not have to be formed with any great care. I

The tightness etweeh the shuttle a and the of their contact surface (a'rc'FGH of Fig; 2) and also by a suitable number of fixed grooves "I, of suitable form and section,'arranged in the wall of the mortise l and extending between the covers 5' and 6 mortise lot the stator is assured by the extent The tightness along the edges of the blade l2 which are in contact'jwith the lateralwall'sfbr covers 5 and 6 of the'sftatorm'ay be assured by' strips of greased feltengaged in grooves arranged in the'said edges or by grooves of suitable sections and positions.

,Where the tenon l G is employed, as in the machine of Fig.3, no permanentjleakage can occur atjthe'placewhere the fixed mortise IB isfhol lowed 'into the wall 6 for the passageof thetenon Iii which fits exactly into the mortise, inasmuch as the diameter of this tenon remains smaller manor equal tothe thickness of the blade.

In connection with certain applications, espe.' cially in the case of simplifiedlow-vacuum or lowepr'e ssure' suction or blower machines or of machines intended'for the displacement of fluids;

loaded with dust (gas generators) it, is possible. to eliminate the scrapers and/orthe strips of felt and be satisfied with a fittingfwith" slight play of the moving parts with respect to the stationary parts. a 1

In order to automatically assure a controlled. lubrication the bearing surface 9 of the shuttle:

a. ca be prolonged bya stub shaft '25 in which; there is arranged one or sever-a1 helical groove 'i dw th lubric nt de uged through a Wic .5 fremasmall :ta ssr. reservoir su h as,

ranged in the cover 6 or any other means. The oil placed under pressure by the movement of the grooves 25 isthereupon delivered through conduits (not shown in the drawings) to the places of the movable parts to be-lubricated (shut tle 8, blade I2 and-driving plate I8). In this manner the flow of the lubricant is proportional to the speed of rotation of the rotary parts. *If one Wishes-to be able to place the machine out of circuit. whenever necessary without its rotor ceasing to be driven, one may add to the said machine a distributor by mean of which the suction ports land the discharge ports 3, may be, for normal operation, placed in communication 'with the suction connection 2' and the discharge connection 3' respectively, or may, when it is desired to'disc-onnect the machine, be isolated fromthe said connections.

The operation of this distributor must be such that when the communication between the corresponding ports and connections is interrupted (operation out of circuit) "the apparatus draws in and directly discharges into the atmosphere which contributes to its rapid cooling-while the circulation of the fluid from inlet to discharge continues to be freely assured, without the intervention. of the said apparatus, by a special bypass channel. I e

One of the simple means of obtaining these results consists in arranging, between the suction port 2 and the suction connection 2', a rotary slide valve 21 and another similar rotary valve 28 between the discharge port 3 and the discharge connection 3', the shafts 21' and 28 of the said slide valves being connected with each other by means of a connecting rod 29, which can b'eoperated bya-joint drive 30. i

Naturally one could use any other suitable combinationior. suitably combining the respective motions of the cylindrical slide valves such as 21 i and 28.

When the slide valves 21 and 28 occupy the positions shown in Figs. 4 and 5, the operation as compressor or pump is normal, the slide valves closing the orifice 3| and 32 through which the suction port -2 and the discharge port 3 can be respectively placed in communication with the open air through the cavity 26.

I On the other hand, when the driving member 30 is brought to its other characteristic position, the slide valves release the orifices 3| and 32,.thus assuring the direct communication of the suction and of the dischargewith the atmosphere, interrupt the communication between 2 and 2' on the onehand and 3 and.,3' on the other hand, and furthermore permit the fluid to circulate independently "of pass 26,.

If necessary one canalso provide at the end of thecase 33 in :which "the slide valves 2! and 28 are placed and at right angle to one of these slide valves or to both, a safety valve 34 communicating with the discharge connection 3 of the compressor in order to protect the inner member thereof against sudden excess pressure or back-firingin case the said compressor should be connected. with a gas generator, for example, or with any other member likely to create these sudden counter pressures.

In order to obtain an operable and efiicient machine of the character described in connection with Figs. 1 to 5, I have found that it is essential that certain ratios exist between the dimensions of the various elements, or at least that such ratios are closely approximated. Also, as hereto-,

the machine through the byforeindicated, the position and: width or the ports is of prime-importancein--insuringvolumete ric emciency and inv preventing communication.

These.- various necessaryor preferred. relations can best. be understood between the chambers.

the blade l2. Witha shuttle'of smaller diameter,,

when the blade I2. lies along. the axis of ymmetry. the length thereof within-the Slot I; wouldbe in? sufficient to insure smooth, operation. of the device and proper rotation of the shuttle by the blade. Furthermore, if. a shuttle of; smaller diameter were employed, some, of the reentrant portion of the cardioid would remain and it would be impossible for the edge of; a blade of finite width to follow. such reentrant surface-powtion. of the stator. On the other hand, with a shuttle of larger diameter, there would necessarily be a. reduction in the volumesv of chambers, l3. and. I4. and consequently a reduction in th ca,- pacity of the machine.

As shown in Fig. 6, the ports 2: and 3 are so positioned in the wall of the stator adjacent the shuttle 8 that lines drawn from o, the retrogression point of the cardioid and the axis of. the shuttle, to points 11, corresponding to points. on the cardioid surface at the edge ofthe ports, make equal angleswiththe-axis of symmetry of the cardioid. I have found thatxmaximum volu-i metric eiiiciency is obtained. when the ports are so located that the points 3): lie on the common tangent, indicated at T, of, the cardioid'. With suchlocation of the edgesof the-ports, each angle is very nearly equal to 60. The volumetric efilciency deteriorates rapidly as. the angle varies from this optimum value. This position of the ports 2 and 3 results purely from theoretical considerations and. hence. is not dependent upon the relative-dimensions of the shuttle. It will be apparent from Fig. 6, however, that with the optimum relative dimensions heretofore given for the blade, shuttle and generating circle, the optimum position of the ports 2 and 3' occurs adjacent the entry of the shuttle into the mortise cutting away the retrogression point and reentrant portion of the cardioid.

The width m of the ports 2 and 3 as indicated in Fig. 6 should be equal to, or less than; the

thickness d of the blade. Preferably the width 111. should be equal to the thickness d and the same is true of the width 9 of the annular mortise l6 for reception of the tenon I6 of the blade. The thickness d of the blade l2 should be between one-fifth and one-tenth the length L of the blade. In the particular embodiment of the invention illustrated in Fig. 6, the thickness d is one-eighth the length L, which i approximately the pref erred ratio.

A machine constructed according to the invention and having its elements proportioned as specified in Fig. 6- will, for a given output and at a given pressure, have the highest volumetric efliciency, with the result that the velocity of the moving parts can be reduced to a minimum. Accordingly the machine, as compared to machines heretofore proposed, will have less frictional losses, will be decidedly less noisy, and the parts will be less subject to wear and will require less lubrication. In the machine the blade works at one-half the speed of the driving member, without the: interposition. of. gears, and is. completelydynamically balanced; When. supportediby tenone at both sides itislikewise mechanicallybalanced and hence not subjecttostresses.

An. important feature.- of the. machine as; above described. isthat. during operation. no pressure surgesv occur, with the result that. the machine can beefilciently employed-as a pumpforcolloida-l liquids, such as milk, wine or the likewhererfoaming; must. be. avoided. Whenthemachine is: used for. such. liquids .or. f orcrude oil or for gases. carrying' dusts or. powdered mineral matter, a forexample when. coupled with agas producer, the. scrapers may be. omitted, and.- a. slight clearance provided. between themovingparts.

Although the-shuttle, in the. embodiments of the-invention illustrated and-above described: is not independently. driven, driving means may. be

provided therefor if; desired. When the machineis operated. at. high pressures, driving means for the shuttle,.as for example gearin between. the.

drive shaft [9 and shaft 25 of the shuttle, if pro.- vided, would: reduce the stress on the driving tenon li.

application is. a. continuation. in. part. of

R my. application. Serial .No- 467,347, filedNovember tudinal arcuate recess, said. rotor comprising a.

cylindrical shuttle and. a. blade, the shuttle being rotatably mounted, in. said casingwith aportion thereof extending v into saidrecess, said shuttle being provided with a. longitudinal diametric slot, theblade; being positioned in-said, slot andtransversely movable therein and beinglofsuch length that the. edge thereof engages the inner surfaceof the casing during rotation of said shuttle, said casing. being. provided with ports each of. a width substantially equal to the. thickness ofthe, blades.

and at, either side of said recess for ingress and egress. of. fluid, and means independent of said shuttle. for driving said blade to cause. an edge thereof to sweep over the internal'isurf'ace ofsaid:

casing.

2. The. rotary apparatus, according to. claim 1, including end walls for said casing andwherein saidlast mentionedmeans include a plate rotatably mounted in one of said Walls, a. spindle on.

said blade rotatably mounted; in said plate, and means for rotating said plate to, cause saidspindle to traverse a circle correspondingto the generator of the cardioid;

3. The rotary apparatus according to claim 1 includingdeformable means carried-by'said blade adjacent the longitudinal edge thereof: for yieldingly engaging the walls of said casing.

4. The rotary apparatus accordingto claim 1 including: end walls secured to said casing; one

of said walls being provided with an annular groove, a plate rotatably mounted in the other of, said walls, an axial extension on said blade extending into said groove; asecond axial extension on said bladerotatably mounted in said plate and-meansfor rotatinasaid. plate;

5. A rotaryapparatus-comprising. in combination a statorand-a rotor; saidstator-comprising a generally cylindrical casing, the internal surface of said casing being so formed that a cross-section thereof is in the form of a cardioid except for the wall section adjacent the retrogression point, said wall section being cut away between the points on the cardioid having a common tangent to provide a longitudinal arcuate recess, said rotor comprising a cylindrical shuttle and a blade. the shuttle having a diametrical slot and being rotatably mounted in said casing with its axis passing through the retrogression point and with a portion of its surfaceengaging the walls of said recess, the diameter of said shuttle being equal to the diameter of the generating circle of the v cardioid, said blade being positioned in said slot and transversely movable therein, the length of said blade being twicethe diameter ofthe shutf tle, said casing being provided with ports at either side of said recess for ingress and egress of fluid.

6. The rotary apparatus according toclaim 5 including end :walls for said casing, a plate rotatably mounted in one of saidwalls, a spindle on said blade rotatably mounted in said plate, and means for rotating said plate to cause said spindle to traverse a circle corresponding to the generator of the cardioid.

'7. A rotary apparatus according to' claim 5 wherein said ports are so located relative to the retrogression point that imaginary lines joining said point with the edges of said ports make an angle of approximately 60 degrees with the aXis of symmetry of the cardioid.

8. A rotary apparatus according to claim 5 wherein the thickness of said blade is between one-fifth and one-tenth the length thereof and vided with ports adjacent said recess, said rotor comprising a cylindrical shuttle and a blade, said shuttle being rotatably mounted in said casing with a portion thereof extending into-said recess and being provided with a diametric slot for recip- 'rocation of said blade therein, and deformable scraper members carried on the longitudinal edges of said blade for engaging the inner surface of said casing duringrotation of said rotor, said scrapers being mounted to permit of limited movement lengthwise of the blade.

' CHARLES BERNARD BRULL.

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