US2044873A - Rotary compressor - Google Patents

Description

June 23, 1936. c BEUST ROTARY COMPRESSOR Filed Nov. 21, 1933 6 Sheets-Sheet 1 E18 29mm \hme 1936- c. J.' BEUST I ROTARY COMPRESSOR Filed Nov. 21, 1935 6 Sheets-Sheet 2 dbtomwgg June 23, 1936. v c ST 2,044,873

ROTARY COMPRES 5 OR gig; 36

"mtg? ,IIIIII mlliziwa 4o c. fIBZuST June 23, 1936. Q BEUST 2,044,873

ROTARY COMPRES S OR Filed NOV. 21, 1935 6 Sheets-Sheet 4 CONDENSER REFRIGERATOR v.

55mm T019 r June 23, 1936. c. J. BEUST ROTARY COMPRESSOR Filed Nov. 21, 195:

6 Sheets-Sheet 5 June 23, 1936. C J, BEUST 2,044,873

ROTARY COMPRES SOR Filed Nov. 21, 1933 6 Sheets-Sheet 6 Patented June 23, 1936 UNITED STATES PATENT OFFICE 2,044,873 ROTARY COMPRESSOR Cecil J. Beust, Atlanta, Ga.

Application November 21, 1933, Serial No. 699,066

17 Claims. (Cl. 230-205) This invention which is a continuation-in-part of my application Serial No. 641,079, filed November 3, 1932, relates to rotary compressors. Its purpose is to provide means for sealing the compression chambers of such apparatus against leakage of the compressed fluid.

Compressors or pumps employing the very desirable fundamental principle of rotary motion have heretofore enjoyed but a limited field of use fulness on account of their inherent fault of slippage or short circuiting of the fluid being pumped or compressed, whereby their volumetric effi ciency is low, and the inefficiency increases in direct ratio to the discharge pressure.

7 New fields have been developed for the employment of fluid pressure pumps or compressors, notably the mechanical refrigeration art, which can tolerate no compression leakage whatsoever, and from which new fields the rotary compressor issubstantially barred on account of its defeet of inherent compression leakage, despite its otherwise ideal mechanical qualifications.

The present invention has for its object the construction of a compressor or pump of any known type in which the chambers are hermetically sealed against leakage by pressures on the outside in excess of the pressures from within and which outside pressures are derived from pressures within.

A more specific object of the invention is t provide means for sealing the chambers'of the rotary pump or compressor, the outside area of which means exceeds the aggregate area pressed against from within the pump or compressor and which sealing means are opposed to the within pressure responsive to fluid pressure acting upon certain localized areas on the outside of said sealing means, ordinarily greater than the areas pressed upon from within, but being ordinarily less than the entire outside area of said sealing means so as to prevent the building up of excessive sealing pressures which might create undesirable or disastrous friction with respect to the rotating parts of the pump or compressor.

Inasmuch as those parts of the rotor of the compressor which are subject to maximum angu lar velocity in the operation of the compressor would be the most susceptible to the destructive friction created by excess sealing pressure against said portions of the rotor of the pump or compressor, the invention contemplates the withdrawing of the fluid pressed areas on the outside of said sealing means away from the peripheral region of said sealing means whereby the peripheral portions of the rotor will be relieved from the maximum value of the sealing pressure.

Another object of the invention is the provision of means for creating an initial pressure bias upon the outer side of said sealing means mm dering the latter effective until suflicient pressure has been generated within the compressor or pump to supplant the initial pressure creating means.

A further object of the invention is to provide 10 in a compressor of the vane type trunnions for taking the end thrust of thevanes when the ends of the latter are exposed to the high pressure at the discharge of the compressor, without transmitting the said end thrust through the rotor itself and to the opposite side thereof.

Still another object of the invention in connection with the trunnions is the provision of split expansion rings seated on said trunnions, with clearance and abutting expansively against the inner ends of the vanes whereby they are constantly pressed against the peripheral wall of the pump or compressor with a resilient pressure which at all times compensates for wear.

Another object of the invention is to provide a compressor in which a single rotor is arranged to draw a plurality of suction pressures of difierent values.

Other objects of the invention will appear as the following description of a preferred and prac- 3 tical embodiment of the invention proceeds.

Although there are probably a number of known types of rotary compressors or pumps to which the present invention may be applied, it has been exemplified in the accompanying drawings by illustrating it in combination with two types of compressor.

In the drawings, the same characters of reference have been used throughout the several figures to designate identical parts: 40

Figure 1 is a vertical side section, a portion of the rotor of the compressor being shown in elevation;

Figure 2 is asection taken along the line 22 of Figure 1;

Figure 3 is a detail taken in a plane perpendicular to the axis of rotation of the compressor illustrating the relation of the expansion ring to the trunnion and to the vanes;

Figure 4 is a section taken along the line 4-4 of Figure 3;

Figure 5 is a horizontal section through the compressor, part being omitted;

Figure 6 is a. section taken along the line 6-6 of Figure 1; 5

I so

Figure '7 is a detail in section taken along the line 1-1 of Figure 6;

Figure 8 is a perspective view of the flexible cupped members or pistons by means of which Scaling pressure is applied to the sealing ring;

Figure 9 .is a perspective view of the sealing ring partly in section;

Figure 10 is a section takenalong the line Ill-400i Figure 9;

Figure 11 is a view in detail showing the un--.

restrained cross-sectional shape of any one of the cupped members or pistons and illustrating the manner in which it is seated within the recesses in the head.

Figure 12 is a view in detail showing the construction of the packing for the outer shoes of the vanes;

Figure 13 is a diagrammatic representation of the lubricant circulation;

Figures 14 and 15 are respectively, vertical sections through an alternative form of compresso taken in perpendicular planes;

Figure 16 is a perspective view of the sealing in Figures Hand 15.; I 7

Figures 17 and 18 are respectively, sections taken along the lines il--Il and l 8l8 of Fig.- ure'16; an'd'T.

ring employed in that form of the inventionshown Figures 19 and 20 are respectively, an exploded perspective. view and; a section view through 'a modified form ofshoe-construction.

Figure -21 is a detail of an alternative construetion to that shown in Figure 5.

Referringfnow in detail to'the several figures and first :adverting to that'form of the inven-- tion shown inFigures 1' and 2, the compressor comprises astator whichincludes-a support I and a casing in general designated by the reference character 2 and comprising a generally cylindrical portion'3 and end heads 4 and 5 suitablyls ecured to the peripheral portion." The inner wall 6 of the peripheral portion is cylindrical. Airo tor I is mounted withinthe space enclosed' be- Y tween the peripheral portion of the casing'and the heads, said rotor being mounted upon arr-axis 8 which is eccentric to the "axis of the peripheral wall of the stator. The diameter of the rotor is such that it makes contact with the inner'peripheral wall of the casing, preferably at the lower side of the compressor.- In order that the region of contact between the rotor and stator may be more than a line of tangency, theinner peripheral "'wall of the rotor, is through lan'appreciable arc; machined to a curvature corresponding to that'of therotor and forming'a'se'at for the motor which will hereinafter 'be'referred to as the arc 'of expulsion. The rotor is [formedwith radial slots; 9 extendingithere=across and op'ening intheenclsof said rotor.- Sliding vanes 'lllaremountedin the slots of said rotor extendinggthere-acros s' and terminating in planes flush with the ends'iof 'saidrot'or. At opposite ends 1 'therotor is formed with circular recesses ll, see

eccentricity, of "the rotor. 7 acts not only 9.52, wear compensating'means for ferring to Figure l the wall of the recess approaches very close to the trunnion adjacent the point l5, but extends quite a distance below said trunnion as shown at IS in the same figure. The slots 9 which serve as guideways for the vanes open into the cylindrical walls of the recesses l I. Expansiblemetallic split rings l1 and I8 are mounted with clearance on the ends of the trunnions which extend within the recesses ll. Figure 4 shows that the rings H are split diagonally widthwise as indicated at IS in Figure 4. The

lower ends of the vanes are provided with a concave semi-cylindrical seat 20 extending thereacross and within said seat a shoe is freely mountved, said shoe having a convex surface matching the concave seat. The working faces of the shoes 2| are concave and the split rings I1 and I8 are expanded outwardly against said shoes, keeping the vanes in intimate contact with the inner peripheral wall of the stator.

On account of the clearance between the split rings and the trunnions, and the frictional presof the bottoms of the vanes against the split rings through an amplitude equal to twice the The ring therefore the vanes; but also asa wear piece to minimize the wear between the shoes 2| and the ring itself. The primary function of the ring and trunnion construction however is to afford a rigid abutment for receiving the end thrust due to the pressure of the compressed fluid against the ends of the vaneswhen the latter become exposed during their period of transit across the discharge port, best shown in Figure 2. In the absence of some fixed abutment such as the trunnions, such end thrust reacts against the rings forcing the rings themselves toward the diametrical opposite side of thestator and pushing the ends of the opposite vanes against the inner peripheral wall of the casing with excessive and destructive pressure.

The upper ends of the vanes are provided with shoe pieces 23 similar to the shoes at the inner ends of the vanes excepting that their working faces are convex corresponding to the curvature of the inner peripheral wall of the casing.

Figure 2 shows that there is a suction port 24 opening at a point 25 adjacent one end of the arc of expulsion and circumscribing the spaces between several of the vanes. On the opposite side of the compressor is a discharge port 26 circumscribing an are somewhat less than the distance between the two vanes and adjacent the opposite end of the arc of expulsion. The space between the rotor and stator on opposite sides of the diametrical line which passes through the middle of the arc of expulsion defines respectively suction and compression chambers. Figure 2 shows a secondary suction port which will be referred to later.

I In that form of the invention illustrated in Figures 1 and 2, the cylindrical portion of the (casing is jacketed as indicated at 28 over that area which circumscribes the compression chamher, the cooling medium being preferably'oil which is admitted by way of the pipe 29 and exited through a discharge conduit 30. This oil has already-come through the interior parts of the compressor as will be later explained and is in general warmer than the fluid admitted to the compressor on the sution side although its temperature is cooler than the compressed fluid.

Therefore, while the oil is useful in cooling the compression chamber, it is in general preferable to restrict it in such manner that it shall not raise the temperature of the inducted fluid.

In the compressor of the type illustrated the leakage which reduces the volumetric efficiency generally occurs at four places, between the rotor and. stator in the arc of expulsion, around the ends of the rotor and vanes, between the ends of the vanes and the inner peripheral wall of the cylinder, and about the vanes in their guideways. Various means have been devised for sealing these points of leakage, and the present invention oflfers nothing new with respect to sealing the joint along the expulsion arc. However, the invention does propose an improved and very versatile means for sealing the compressor against leakage around the sides of the vanes, over the tops 01' the vanes and back of the vanes by impressing upon the sealing instrumentalities predominant pressures derived from pressures within the compressor itself.

In my application for patent of which the present is a continuing application, is disclosed a sealing ring forming an end wall for the compression and suction chambers and a piston on the outside of said sealing ring and co-extensive with the area thereof with means forapplying the high pressure of the compressor discharge to the rear of this piston for biasing the sealing ring in opposition to the pressures within the suction and compression chambers.

In practice it was found that this sealing pressure was ordinarily so excessive as to produce unnecessary friction stresses between the ends of the rotor and vanes and the sealing ring which made it difficult to rotate the rotor and furthermore led to rapid wear of the engaging parts.

The invention as embodied in the present continuing application includes the sealing ring 3| seated in a suitable recess in the head and having its outer peripheral edge co-incident with the inner peripheral cylindrical Wall of the casing. The width of the sealing ring is such that it extends substantially to the bases of the v'anes Ill. The sealing ring 3| rests against the sides of the vanes and the intervening portions of the rotor. It is normally, in the initial state of repose of.

the compressor, kept thus pressed by a plurality of small springs 32 seated in recesses 33 in the head 4 and pressing outwardly against said ring. These springs are of course totally inadequate to maintain a sealing pressure after the pressures within the compressor build up, but they merely prevent leakage when the compressor first starts and when there is very little differential between inside and outside pressures.

In order to avoid the excessive endwise thrust against the rotating parts of the compressor which the imposition of discharged pressure over the whole outer face of the sealing ring engenders and as covered in the parent application, the present invention contemplates in its broadest aspect segregating the portions of the area of the outer side of the sealing ring which lie opposite the compression and suction chambers, and applying to those segregate areas pressures from within the compressor proportional to the pressures to be sealed in. For example, high discharge pressure would be imposed upon that part of the ring opposite the compression chamber, and

suction pressure against that part of the ring which overlies the suction chamber, it being understood of course that the outside area of the sealing ring is at all times greater than the inside surface of said ring pressed upon by the within pressures since part of tne inside area of the ring is occluded by the sides of the vanes and by the intervening end portions of the rotor. It is also to be understood that the areas of the outer surface of the ring respectively impressed with 10 the discharge pressure and the suction pressure are always in excess of the pressures to be sealed and it is therefore quite feasible to use a lower pressure value on the outside of said ring to seal a higher pressure within. 15

A third pressure is available Within the compressor. A certain amount of internal leakage is inevitable from the high to the low side of the compressor around one or another of the relatively moving parts so that in the oil spaces with-- 20 in the central portion of the compressor there is a pressure value which is a mean between the high pressure of the compression chamber and the low pressure of the suction chamber.

In the preferred embodiment of my invention this intermediate pressure may be employed.

In order to segregate the high and low pressure areas on the outside of the sealing ring, the adjacent head 4 is provided with recesses 34 of more or less crescent shape corresponding to the shapes of the chambers opposite which they lie, the cusps 36 and 3l'of said recesses being adjacent the are of expulsion. Since it will in general be necessary to seal the joint along said are of expulsion against leakage a third recess 38 is provided at this point. Pistons are arranged in said recesses. The pistons may be of any suitable construction, but in the present embodiment of the invention they consist of flexible cupped rubber members 39, 40 and 4| having side flanges 42 and 43 terminating in feather edges 44. Figure 11 shows that in their unconfined state, the flanges of the cupped members flare slightly and the bottom 45 bulges slightly outward. Said cupped members are crowded into the respective recesses in inverted position in the manner indicated in the lower half of Figure 11 so that there is an inherent pressure of the flanges 43 against the corresponding walls of the recesses. The spaces enclosed beneath the cupped members or pistons 5 39, 40 and 4| form pressure chambers adapted to be placed in communication by suitable conduits with sources of compression within the compressor. When the pistons 39, 49 and 4| are in place, the slightly bulged bottoms of said pistons press against corresponding areas of the sealing ring.

Figure 5 shows that the discharge port 26 is connected by a system of conduits 46 suitably bored through the casing to the pressure chamber back of the piston 39. Instead of making use of the suction pressure to activate the piston 40 which presses that part of the sealing ring opposite the suction chamber, the intermediate pressure is employed and consequently Figure 5 5 does not show the suction port communicating with the pressure chamber behind the piston 49. By reference to Figure 1 however, it will be observed that the space 3 between the trunnion and rotor and in which this intermediate pressure builds up, is connected by conduits 41, 48 and 49 with the pressure chamber back of the piston 46. The piston 4| which overlies that part of the ring opposite the joint along the expulsion arc is actuated in response to the intermediate pressure de- 7| rived from one of the oil passages 50 by way of a conduit 5| best shown in Figure 6.

If it were desired to use the suction pressure instead of the intermediate pressure to seal the suction chamber, the latter chamber would be tapped into the back of the piston 40, in a similar manner to that illustrated in connection with the leading of the discharge pressure to the back of the piston 39.

It has been stated that initial sealing contact between the sealing ring and the sides of the vanes and rotor is normally accomplished by means of the springs 32. As an alternative or an auxiliary to the springs 32, fluid pressure means may be employed for maintaining this initial sealing relationship of the parts. With this object in view, the suction port is tapped by means of a conduit 52 leading to the back of that part of the sealing area not contacted by the pistons 39, 4|] and 4 When the compressor first starts, the pressure behind the several pistons is nil or at least not greater than the pressures within the compressor. The area subjected to these pressures is however temporarily augmented by pressure-from the suction port being applied as indicated to the area of the sealing ring not affected by the pistons. Thus the entire outside area of the sealing ring is pressed by a pressure which may be not in excess of the pressure within the compressor, nevertheless, since the outside area is greater than the inside area, the aggregate area on the outside exceeds that on the inside of the compressor and the sealing ring is initially biased in a sealing direction.

Figure 5 shows the conduit 52 controlled by an adjustable needle valye '5'3 which is not intended to be frequently adjusted, but merely once for all, according to the amount of auxiliary pressure which may be required in addition to the springs 32 or in the absence of such springs according to the amount of pressure necessitated to effect the proper initial sealing of the sealing ring.

The provision of the localized areas of differential pressure on the outside of the sealing ring, and the pistons by means of which this differential pressure is applied, constitutes an extremely versatile arrangement permitting the said localized areas to be modified or shifted in designing various compressors, according to their size, the speed at which they are to be operated and the pressures which they are called upon to produce. For example, it has been found, particularly with-large sized compressors, that the angular velocity of the tips of the vanes gives rise to a condition of destructive friction when the sides of the tips of the vanes are excessively pressed particularly when the compressor is compressing to high pressures. In designing such compressors, it becomes necessary merely to remove the localized areas away from the peripheral region of said vanes, while still maintaining an extent of their area which insures that a predominant pressure will be applied to the outer side of the sealing ring. The tips of the vanes are thus relieved from excess pressures while at the same time the necessary sealing pressures are maintained.

It will be understood with reference to this ,phase of the invention that while the sealing means above described may be applied separately to both sides of the compressor, it is deemed necessary in general only to apply the sealing ring to one side, since the pressure of the pistons against said sealing ring is transmitted to the rotor and vanes, pushing them bodily over into contact with the machined surface of the opposite head.

Leakage from the chambers of the compressor around the peripheral faces of the sealing ring 3| is prevented by means of continuous flexible piston packings 54 and 55 seated in inverted portion in channels 56 and 51 formed in the said peripheral walls of said sealing ring. The faces of said pistons make contact with the adjacent side walls of the recesses in said head in which said piston packings are mounted. The spaces enclosed behind said piston packings are placed in communication with suitable sources of pressure from within the compressor. Since the joints which these piston packings seal are fixed except for a very slight range of sliding movement in a direction parallel to the axis of the rotor, the problem of nicely egulating the sealing pressure to prevent undue frictional wear or resistance is lacking. However it is a step in the nature of good engineering to employ a sealing pressure which is not grossly in excess of the sealing needs. Therefore, while it is quite within the range of the invention to utilize the discharge pressure of the compressor for projecting these piston packings against the walls with which they react, it is preferred to employ the intermediate pressure from the interior of the compressor between the suction and compression chambers. This is accomplished by providing grooves 58 and 59 in the outer face of the sealing ring, the groove 58, shown in Figure 1, being in communication with oil conduits 60 extending transversely through the rotor and the contents-\of which conduits are under the desired intermediate pressure through various minute leakage sources between the compression chamber and the suction chamber of the compressor, while the groove 59 derives its pressure from the interior displacement space on the discharge side.

The grooves 59 are shown in duplicate and spaced apart a distance equal at least to the width of one of the vanes, for the simple reason that since theyare shown as being radially directed, they are'occluded by each vane in the course of its rotation. If there were only one groove 58 there would be a periodic cutting off of the pressure from the piston packing 55. Since the two grooves are spaced apart a distance equal at least to the width of the vanes both can never be occluded at the same time and consequently the pressure behind the piston packing 55 is uninterrupted.

Referring now-to Figures 2, 3 and 4, and Figures 12, 19 and 20v showing details, attention is directed to the means for preventing the short circuiting of the compression pressure around the vanes. Figures 2, 3 and 4 show that the vanes ID are each provided with a shoe 2| at its lower end and a shoe piece 23 at its upper end, the shoes and shoe pieces being oscillatably seated in concave cylindrical seats in the ends of said vanes. The shoes 2| which bear against the split ring I! merely act as wear pieces and to keep the entire ends of the vanes in contact with the split ring instead of a mere line of contact as would normally be the case due to the canting of the vanes relative to the split ring on account of the eccentricity of the rotor relative to the trunnions. Wear between the inner ends of the vanes and the split ring is thus distributed over the whole area of the shoe instead of being concentrated along a mere line of contact. The shoes 2| are not particularly concerned with sealing with the adjacent parts against pressure leakage for this is taken care of in connection with the packing of the vanes and the upper shoe pieces.

Figure 12 shows that the rotor is provided both in front; of and rearwardly thereof with reference to its direction of rotation with channels 6| and 62 in which are seated wear pieces 63 and 64 extending widthwise the full length of the rotor and flush with the rotor and vanes, said wear pieces being packed by flexible pistons 65 and 66 hermetically fitting the channels in which they lie and being in general of the same construction as the flexible pistons 39, 40 and 4| and the piston packings 54 and 55. The spaces enclosed within said channels by the respective pistons form pressure chambers, the chamber on the advance side of the vane being in communication with the compression chamber by means of a bore 61 while the chamber on the trailing side of the vane is in communication by way of a bore 64" with the space in the rotor back of the vane III which space is under the intermediate pressure of the compressor said pressure being transmitted through the ends of the vane slots which open as shown in Figure 2 into a space in the middle of the end plate, which space receives inevitable pressure leakage from both the compression and suction chambers and is also subject to the pressure of the lubrication system. Thus each side of the vane is sealed against leakage by a pressure superior to that which it opposes.

Figure 12 shows also that the shoe piece 23 is biased actively outward against the inner peripheral wall of the casing of the stator by a wear piece 68 positioned at the open end of a channel 69 formed in the vane beneath said shoe piece,

and backed by a flexible piston 10 subject to pressure within the chamber H derived by way of the conduit 12 from the high compression side of the vane l0.

The shoe piece 23 shown in Figure 12 and illustrated in the preferred embodiment of the invention is symmetrical in cross section. A modified form of the invention is shown in Figures 19 and 20 in which the shoe is of asymmetrical cross section, the predominant portion 13 of which extends into the high compression chamber and presenting a broad ledge or shoulder I4 to the pressure in said chamber through which medium it is canted into firm frictional contact with the inner peripheral wall of the casing. The

shoe in this form of the invention is shown as provided with a separable and therefore replaceable wear piece I5 grooved as at 16 to receive any suitable form of packing strips 11.

In this form of the invention the shoe piece is provided with a cylindrical channel 18 having a cross section greater than a semi-circle, and receives a correspondingly shaped bead 19 formed on the end of the vane, said shoe being irremovable radia ly, but readily removable for replacement by sliding it in a transverse direction after the rotor has been removed from the casing. The joint between the shoe and the end of the vane is packed in a manner similar with that shown in connection with the form of the invention exemplified in Figure 12, a wear piece being provided in a channel 8| formed in the shoe, said wear piece abutting the surface of the bead l9 and being backed by a flexible piston 82 in communication with the pressure of the compression chamber by way of a bore 83.

In connection with the packings on the advance and trailing s des of the vanes and in as sociation with the joints between the outer shoe pieces and the vanes, light sinuous springs 84 are placed behind the flexible pistons to impart initial sealing pressure to said pistons before the compressor upon starting has had the opportunity to generate the normal effective pressures.

It will be understood, in contemplating the operation of the compressor that all of the interstices between the various parts excluding of course the suction and compression chambers are filed with oil and that the fluid pressure impressed upon the various pistons is transmitted by the medium of oil. This oil is circulated by a pump 85 to the jacket 28, see Figure 13. From the jacket it flows to a suitable cooler 85 from which it is conducted by a conduit 81 to an oil chamber 88 adjacent the bearing on one side, see Figure 1, from which it flows through the bearing and through a series of conduits 60 in the rotor, through a series of oil passages 50 in the boss 89 of the head 4 which supports the trunnion l3, through the opposite bearing and again to the pump by way of a passage 90.

A certain amount of oil necessarily-finds its way into the suction or compression chambers mixing with the fluid to be compressed, the oil and compressed fluid being conducted to a sep aratorll, see again Figure 13, and in the case to draw two distinct suction pressures by one end of the same compressor. This may be ac complished in the present invention by providing the primary and secondary suction or induction ports 24 and 21 respectively. The primary suction port communicates with the suction chamber at the advance end thereof and therefore pulls the lowest pressure. By the time the suction chamber has rotated to the point at which it communicates with the secondary induction portion it is already occupied with fluid taken in at the primary induction portion so that it is capable of drawing upon the secondary induction port with a higher pressure value. The primary induction port may lead from a coil at a low ice making temperature 15 F., while the secondary induction port may lead from a coil at a higher temperature such for example as is suitable for keeping an ice storage room at or just before freezing, 28-32 F.

Referring now to that form of the invention illustrated in Figures 14, 15 and 16, a compressor of the gear type is illustrated, the rotor comprising two meshing gear impellors operating within a chamber formed by a casing having a cylindrical peripheral portion 91 and closed by heads 98 and 99. The problem of sealing insofar as it is generic to this form of the invention and previously described is confined to the end seal I00 shown at the left of the rotor elements in Figure 14 and which is similar in construction and in mode of operation to the first described form of the invention excepting of course that its shape is modified in accordance with the shape of the rotor chamber, the sealing ring being illustrated in Figure 16 and being in the form of a figure 8. The head 98 between which and the rotor elements the sealing ring Hill is placed is provided with suitably located recesses in which the flexible cupped pistons l0l and I02 are seated.

compression chamber between the gears while the piston I 02 is much larger, following the shape of the suction and transfer chambers of the compressor. In position, extent and construction, these pistons follow the same principles as do corresponding parts of that form of the invention shown in Figures 1 and 2. Figure 14 shows that the piston llil which seals the compression chamber derives its opposing pressure from the discharge chamber of the compressor while the piston I02 is in communication with suction pressure derived from the interior of the compressor through a conduit I03. The peripheral edges of the sealing ring Hill are provided with channels and endless piston packings seated therein in the same manner as is illustrated in connection with the preferred form of the invention. Figure 16 shows that these peripheral packing pistonsjeceive their operating pressure byway of grooves I04 formed on that face of the sealing ring which is adjacent the interior of the compressor.

It will be understood that the specific means for sealing against the various phases of leakage as described and illustrated in the foregoing disclosure are merely illustrative and by no means to be construed as limiting the scope of the invention, which includes broadly all novel equivalent constructions for accomplishing the new and advantageous results as herein set forth.

What I claim is:

1. Rotary compressor comprising a casing, a rotor withinsaid casing, said rotor co-operating with the inner peripheral wall of said casing and with suitable end wall structure to form suction and compression chambers, including a sealing member forming an end wall for at least one side of said suction and compression chambers making endwise contact with said rotor whereby the area of said end wall exposed to pressure within said chambers is less than the entire area of the outer side of said end wall, means for pressing said end wall against said rotor by externally applied fluid pressures derived from pressures within said compressor, and means for restricting the application of said derived pressures to areas on the outer side of said end wall remote from the outer peripheral portion thereof for relieving the peripheral portions of the rotor, that is to say, those parts having maximum angular velocity, from excess endwise friction, said restricting means comprising ahead between which and the side of the rotor said end wall is positioned, said'head having recesses opening in the face thereof, the open sides of which delineate the said areas, flexible cupped members hermetically fitting said recesses and forming therewith pressure chambers, the bot toms of said cupped members contacting said end wall and the derived pressures being in communication with said pressure chambers, the extent of said areas being sufliciently less than the entire area of the outer side of said end wall to avoid excessive sealing pressure but sufficiently great to oppose a predominant pressure to the pressure within said chambers.

2. Rotary compressor comprising a casing, a rotor within said casing and eccentrically mounted with respect to the interior peripheral wall of said casing so as to contact the latter through an appreciable arc, vanes slidably guided by said rotor engaging the peripheral wall of said casing and terminating flush with the ends of said rotor, said rotor, vanes, the inner peripheral wall of said casing and suitable end wall structure co-operating to form suction and compression chambers on opposite sides of said arc, including a sealing member forming an end wall for at least one side of said suction and compression chambers making endwise contact with said rotor and said vanes whereby the area of said end wall exposed to pressure within said chambers is less than the entire area of the outer side of said end wall, means for pressing said end wall against said rotor and vanes by externally applied fluid pressure derived from pressures within said compressor, and means for.restricting the application of said derived pressures to areas on the outer side of said end wall remote from the outer peripheral portion thereof for relieving the peripheral portions of said vanes, that is to say, those parts having maximum angular velocity from excess endwise friction, said restricting means comprising'a head between which and the side of the rotor said end wall is positioned, said head having recesses opening in the face thereof, opposite the chambers to be sealed, the open sides of which delineate the said areas, flexible cupped members hermetically fitting said recesses and forming therewith pressure chambers, the bottoms of said cupped members contacting said end wall and the derived pressures being in communication with said pressure chambers, the extent of said areas being sufficiently less than the entire area of the outer side of said end wall to avoid excessive sealing pressure, but sufliciently great to oppose predominant pressures to the pressures within said chambers.

3. Rotary compressor comprising a casing, a rotor within said casing eccentrically mounted with respect to the interior peripheral wall of said casing so as to contact the latter throughout an appreciable arc, vanes slidably guided by said rotor engaging the inner peripheral wall of said casing, said vanes, rotor, the inner peripheral wall of said casing combining with suitable end wall structure to form suction and compression chambers, on opposite sides of said arc, including a sealing member forming an end wall for at least one side of said suction and compression chambers making endwise contact with said rotor and said vanes whereby the area of said end wall exposed to pressure within said chambers is less than the entire areas of the outer side of said end wall, means for pressing said end wall against said vanes and rotor by externally applied fluid pressures derived from pressures within said compressor at values proportional to the pressures to be sealed, and means for restricting the application of said derived pressures to areas on the outer side of said end wall remote from the outer peripheral portion thereof for relieving the peripheral portions of the vanes, that is to say, those parts having maximum angular velocity, from excess endwise friction, said restricting means comprising a head between which and the side of the rotor and vanes said end wall is positioned, said head having recesses opening in the face thereof opposite the chambers to be sealed and opposite said are of contact, the open sides of which recesses delineate the said areas, flexible cupped members hermetically fitting said recesses and forming therewith pressure chamberathe bottoms of said cupped members contacting said end wall and the derived pressure being in communication with said pressure chambers, the extent of said areas being sufliciently less than the entire area of the outer side of said end wall to avoid excessive sealing pressure, but sufliciently great to oppose predominant pressures to the pressures within said chambers. I

compressor as claimed in claim 3, the

cupped member opposite said are of contact derotor co-operating with the inner peripheral wall of said casing and withsaid head to form suction and compression chambers, including a sealing member forming an end wall for at least one side of said suc. ion and compression chambers, fitting within the chamber of said casing against the.

inner peripheral wall of said casing on the one hand and upon a portionof said head on the other, said end wall making endwise contact with said rotor whereby the area of said end wall exposed to pressures within said chambers is less than the entire area of the outer side of said end wall, the edges of said end wall which abut the peripheral wall of said casing and said rotor being formed with channels, endless flexible channeled 7 members seating within the channels of said end wall with their flanges in hermetic elation to 'the sides of said channels and their bottoms engaging respectively the inner peripheral wall of said casing and said head, the channels in said end wall and said flexible members forming pressure chambers communicating with sources of pressure within said compressor, means for pressing said end wall against said rotor by externally applied fluid pressures derived from pressures within said compressor, and means for restricting the application of said derived pressures to localized areas on the outer side of said end wall,

recesses in said head opening in the face thereof,

pistons hermetically fitting said recesses and forming therewith pressure chambers, the bottoms of said pistons contacting said end wall in surfaces defining said areas and the derived pres sures being in communication with said pressure chambers, the extent of said areas being sufliciently less than the entire area of the outer side of said end wall to avoid excessive sealing pressure, but sufliciently great to oppose predominant pressures to the pressures within said chambers.

6. Rotary compressor comprising a casing, a,

rotor within said casing, said rotor co-operating with the inner peripheral wall of said casing and with suitable end wall structure to form suction and compression chambers, including a sealing member forming an end wall for at least one side of said suction and compression chambers making endwise contact with said'rotor whereby the area of said end wall exposed to pressure within said chambers is less than the entire area of the outer side of said end wall, means for pressing said end wall against said rotor by externally applied fluid pressures derived from pressures within said compressor having values proportional to the pressures. to be opposed, means for restricting the application of said derived pressures to I areas on the outer side of said end wall opposite the respective chambers to be sealed, remote from the outer peripheral portion thereof for relieving ity, from excess endwise friction, the extent of said areas being sufliciently less than the entire area of the outer side of said end wall to avoid excessive sealing pressure, but sufllciently great to oppose a predominant pressure to the pressures within said chambers, and means for imparting an initial sealing bias to said end wall comprising a conduit leading from a source of pressure within said compressor to the outer side of said end wall outside of said restricted areas. j

'7. Rotary compressor comprising a casing, a rotor within said casing and eccentrically mounted with respect to the interior peripheral wall of said casing so as to contact the latter through an appreciable arc, vanes slidably guided by said rotor engaging the peripheral wall of said casing and terminating flush with the ends of said rotor, said rotor, vanes, the inner peripheral wall of said casing and suitable end wall structureco-operatingto form suction and com-,

pression chambers on opposite sides of said are,

including a sealing member forming an end wallfor at least one side of said suction and compression chambers making endwise contact with said rotor and said vanes whereby the area of said end wall exposed to pressure within said chambers is less than the entire area of the outer side of said end wall, means for passing said end wall against said rotor and vanes by externally applied fluid pressure derived from pressures within said compressor, means for restricting the application of said derived pressuresto areas on the outer side of said end wall remote from the outer peripheral portion. thereof for relieving the peripheral portions of said vanes, that is to say, those parts having maximum angular velocity-from excess endwise friction, said restricting means comprising a head between which and the side of the rotor said end wall is positioned, said head having recesses opening in the face thereof, opposite the chambers to be sealed, the open sides of which delineate the said areas, flexible cupped members hermetically fitting said recesses and forming therewith pressure chambers, the bottoms of said cupped members contacting said end wall and the derived pressures being in communication with said pressure chambers. the extent of said areas being sufllciently less than the entire area of the outer side of said end wall to avoid excessive sealing pressure, but sufliciently great to oppose predominant pressures to the pressures within said chambers, andmeans for imparting an initial sealing bias to said end wall comprising a conduit leading from a source of pressure within said compressor to the outer side of said end wall outside of said restricted areas. 7

8. Rotary compressor comprising a casing, a rotor within said casing, said rotor co-operating with the inner peripheral wall of said casing and with suitable end wall structure to form suction and compression chambers, including a sealing member forming an end wall for at least one side of said suction and compression chambers mak-' -ing the application ofsad derived pressures to localized areas on the outer side of said end wall, said means comprising a head between which and the side of the rotor said end wall is positioned, said head having recesses opening in the face thereof, pistons hermetically fitting said recesses, the bottoms of said pistons contacting said end wall on surfaces which delineate said areas, being biased thereagainst by said derived pressures, the

extent of said areas being sufliciently less ,than the entire area of the entire outer wall to avoid excessive sealing pressure but sufficiently great to oppose predominant pressure to the pressure within said chambers.

9. In combination with arotary compressor comprising a casing and a rotor therein, defining between them'a chamber, the rotor being eccene trically mounted on a shaft coaxial with the cir-IJ cumferential wall of said casing, said rotor being; a I 7 -extent of said areasto which pressure is applied being s'uflicientlyless than the entire area of the formed with radial guideways, and sliding varies in said guideways projectable into said chamber" and bearing against theperipheral wall of said casing, means for sealing said vanes against pressure leakage between themselves and said guideways, comprising a channel opening in the joint between said varies and guideways, a sealing element in said channel to close said joint, and means for placing the space within said channel behind said sealing element in communication with said chamber.

' 10. In combination with a rotary compressor, comprising a casing and a rotor therein, defining between them a chamber, the rotor being eccentrically mounted on a shaft coaxial with the circumferential wall of said casing, said rotor being formed with radial guideways, and sliding vanes in said guideways projectable into said chamber and bearing against the peripheral wall of said chamber, said vanes separating said chamber into parts having differential pressures on opposite sides of said vanes, means for admitting fluid under dominant pressure derived from the discharge pressure of the compressor to the inner ends of the guideways behind said vanes, said rotor being formed with channels opening in the joints between each vane and its guideway on opposite sides of the said vanes, packing members in said channels extending through the width of said vanes and bearing against said vanes to close said joints, means for placing the space within the channel behind the packing on the advance side of-said vane into communication with the part of the first named chamber in advance of said vanes, and means for placing the space within the channel behind the packing on the trailing side of said vane into communication with fluid under pressure behind said vanes.

11. Rotary compressor comprising a casing, a rotor within said casing, said rotor cooperating with the inner peripheral wall of said casing and with suitable end wall structure to form suction and compression chambers, including a sealing member forming an end wall for at least one side of said suction and compression chambers, making an endwise contact with said rotor whereby the area of said end wall exposed to pressure within said chambers is less than the entire area of the outer side of the said end wall, means for pressing said end wall against said rotor by exi ternally applied fluid pressures derived from pressures within said compressor, said pressure applying means having an area of contact with the ing endwise contact with said rotor whereby the area of said end wall exposed to pressure within said chambers is less than the entire area of the outer side of said end wall, means for pressing,

to the internal pressure of said compressor, the

outer side of said end wall to avoid excessive, sealing pressure but suflficiently great to oppose a predominant pressure to the pressures within said chambers.

13. In a compressor including a casing and a rotor within the casing, a sealing ring within the casing abutting an end of the rotor and forming an end wall of the compression and suction chambers of the compressor, said ring having a peripheral channel, a sealing piston seated in said channel forming a movable wall of the pressure chambers defined by the walls of said channel and the said sealing piston, co-acting with the peripheral wall of said casing, said pressure chamber being in communication with an internal pressure of the compressor.

14. In a compressor including a casing and a rotor within the casing,- a sealing ring within said casing abutting an end of the rotor and forming the end wall of the compression and suction chambers of the compressor, the outer peripheral face of said ring cooperating sealingly with the peripheral wall of said casing, said ring having an inner peripheral face adapted to coact with the outer surface of a boss extending inwardly from said casing, said inner and outer peripheral faces being formed with channels, sealing pistons seated in said channels forming movable walls of the pressure chambers defined with the peripheral wall of said casing and the outer surface of said boss, said pressure chambers being in communication with an internal pressure of the compressor.

15. In a compressor including a casing and a rotor within the casing, a sealing ring within said casing abutting an end of the rotor and forming the end wall of the compression and suction chambers of the compressor, the outer peripheral face of saidring cooperating sealingly with the peripheral wall of said casing, said ring having an inner peripheral face adapted to co-act With'the outer surface of a boss extending inwardly from said casing, said inner and outer peripheralfaces being formed with channels, sealing {pistons seated in said channels forming movable walls of the pressure chambers defined between the walls of said channels and said seal- Jing pistons, said pistons co-acting respectively with the peripheral wall of said casing and the .outer surface of said boss, said pressure chambers being in communication with sources of pressures within the compressor proportional to the pressures against which they are opposed.

l6. Rotary compressor comprising a casing, a rotor therein, said rotor cooperating with the inner peripheral wall of said casing and with suitable end wall structure to.form suction and v compression chambers, including a sealing ring forming an end wall for at least one side of said suction and compression chambers, making endwise contact with said rotor, means for pressing said end wall against said rotor by fluid pressures derived from pressures within said compressor and having values proportional to the pressures to be opposed, the said means restricting said pressures to segregated areas of said wall, said sealing ring having a peripheral channel, a sealing piston seated in said channel forming a movable wall or the pressure chamber defined by the walls of said channel and said sealing piston, said sealing piston co-acting with the peripheral wall of said casing, said pressure chamber being in communication with an internal pressure of the compressor.

17. Rotary compressor comprising a casing, a rotor within said casing, said rotor cooperating with the inner peripheral wall of said casing and with suitable end wall structure including a head of the casing, to form suction and compression chambers, including a sealing member forming an end wall for at least one side of said suction and compression chambers, making endwise contact with said rotor whereby the area of said end 2 wall exposed to pressure within said chambers is less than the entire area of the outer side 0! said end wall, means between said head and end wall for pressing the latter against said rotor by externally applied fluid pressures, derived from pressures within said compressor, said means being constructed to restrict the application oi. said derived pressures to localized areas on the outer side of said end wall, said means comprising pisions hermetically fitting recesses formed in the head or sealing ring, the bottoms of said pistons occluding the open sides of said recesses and contacting the surfaces of the adjacent member which delineate the said localized areas, being biased thereagainst by said derived pressures, the extent of said areas being sufliciently less than the entire area of the entire outer wall or said sealing means to avoid excessive sealing pressure, but being sufliciently great to oppose predominant pressure to the pressure within said chambers.

CECIL J. BEUST.

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