CA1109038A - Compressor-expander of the vane type having canted vane cavity - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

A compressor-expander having a vaned rotor in which the vanes rotate about an axis which is canted with respect to the rotor axis. The housing of the device has a disc-shaped main cavity having adjacent hub recesses which are concentrically spherical. The cavity is in the form of a doubly truncated sphere canted with respect to the shaft axis. The rotor has a central spherical portion for mating with the recesses and includes an integral Saturn-like ring extending to the outer wall of the cavity to divide the cavity into compressor and expander sides of complimentary circular wedge shape. The vanes occupy radially extending slots in the rotor and serve to separate each side into successive chambers which vary cyclically in volume as the shaft rotates without requiring the vanes to bodily reciprocate either radially or axially. The cavity is provided with compressor and expander inlet and outlet ports, a primary heat exchanger being connected between the compressor outlet port and the expander inlet port, so that air entering the compressor inlet is compressed and heated, the heat of compression being removed in the heat exchanger, following which the air is expanded and cooled for discharge in the cooled state. Preferably a secondary heat exchanger is connected between the expander outlet and the compressor inlet to form a closed system operated at a pressure above atmospheric. By appropriate location and connection of the ports, the device may be utilized as a two-stage compressor or expander.

Description

11~9~38 The use of positive displacement rotary compressor-expander devices for refrigeration and air conditioning purposes is well known in view of prior patents including ~.S. patent 3,686,893 filed December 19, 1972 and U.S.
patent 3,904,327 filed September 9, 1975. Such patents have been characterized by the use of a vaned rotor operating in a housing having an elliptical cavity, the vanes being radially movable with respect to the rotor to define chambers which cyclically expand and contract in volume.
It is an object of the present invention to provide an improved compressor-expander in which the vanes move axially, instead of radially, with respect to the rotor. It is, accordingly, an object to provide a compressor-expander in which opposed ones of the vanes may be integral with one another thereby cancelling out the effect of centrifugal force upon the vanes. This makes it unnecessary to provide rollers or the like for supporting the vanes against the effect of centrifugal force thereby reducing the amount of friction and bringing about a substantial simplification of the construction.
It is a related object of the invention to provide a compressor-expander in which any bodily reciprocation of the vanes with respect to the housing is avoided and in which there is almost pure rotational movement about the vane axis. Thus it is an object to provide a compressor-expander which may be operated at substantially greater speed than conventional compressor-expanders with a correspondingly greater through-put and heat rate without paying a price in the form of increased wear and vibration.
It is a related object to provide a compressor-expander which, because of its higher permissible speed, may, for a ~,~ ~. .

given heat rate, be more compact and of lighter weight than prior compressor-expanders. In this connection it is an object to provide a device which is ideally suited to use as a heat exchanger in winter-summer operation.
It is a further object to provide a compressor-expander in which the compressor and expander sides may be thermally more isolated from one another resulting in less short circuiting of heat with a corresponding increase in thermal efficiency.
It is another object of the present invention to provide a compressor-expander which may be more simply and effectively lubricated than prior devices of the radially reciprocating vane type.
It is a general object of the present invention to provide an improved compressor-expander which not only has improved operating qualities but which, under conditions of quantity production, gives promise of greater economy, longer life and reduced maintenance.
In accordance with the present invention there is provided a rotary machine comprising in combination a housing having means for journalling a shaft therein, the housing defining a disc-shaped main cavity having adjoining hub recesses, the main cavity being in the form of a doubly truncated sphere symmetric about a vane axis which is canted with respect to the shaft axis, a rotor in the housing having axially projecting stub shafts, the rotor including a Saturn-like ring symmetric about the shaft axis, the ring extending to the outer wall of the main cavity dividing the cavity into first and second sides each of circular wedge shape having thick and thin portions arranged in complementary fashion, the ring having radiallyextending slots generally aligned with the shaft axis to divide the ring into sectors, vanes in the slots, the vanes having a profile substantially corresponding to the profile of the truncated sphere to separate each side into successive chambers which vary cycli-cally in volume as the shaft rotates, each side having an inlet port and an outlet port in straddling relation to the thin portion ~hereof and in which the vanes are provided in opposed pairs, the vanes comprising each pair being inter-connected such that the vanes of a pair are connected by at least one narrow neck, with the narrow necks having cooperating axial offsets for interfitting with one another, the lateral edges of the vanes being rounded and the thickness of the vanes being such as to provide substantially constant clearance between the vanes and the sidewalls of the main chamber through-out the course of a rotative cycle.
Other objects and advantages of the invention will become apparent upon reading the attached detailed description ;~ and upon reference to the drawings in which:
Figure 1 shows a compressor-expander constructed in , accordance with the present invention in the form of a vertical section taken along line 1-1 in Fig. 2.
Fig. la is a partly diagrammatic end view of the device looking along line la-la in Fig. 1 and showing the connection of heat exchangers.
Fig. lb is a diagram showing the two wedge-shaped sides into which the housing cavity is divided.

- 2a -Fig. 2 is a view of the interior of the device of Fig. 1 looking along line 2-2 therein with the left-hand end bell removed.
Fig. 3 is a perspective view showing the rotor of Figs. 1 and 2 with the vanes assembled therein.
Fig. 4 shows the interior of the left-hand end bell looking along line 4-4 in Fig. 1 with the rotor removed to reveal the porting on the compressor side.
Fig. S is a view similar to Fig. 4 but looking in the opposite direction to show the porting on the expander side.
Fig. 6 is a fragmentary section taken along line 6-6 in Fig. 4 showing the compressor outlet port.
Fig. 7 is an elevational view of the rotor body~
Fig. 8 shows the shaft end view of the rotor body looking along line 8-8 in Fig. 7.
Fig. 9 shows the blind end of the rotor body looking along line 9-9 in Fig. 7.
Fig. lOa is a section taken through one of the slots in the rotor body looking along line lOa-lOa in Fig. 8 with the stub shafts in exploded relation.
Fig. lOb is an adjacent section looking along line lOb-lOb in Fig. 8.
Fig. 11 shows a modified form of rotor body made up of individual sectors held together by screws.
Fig. 12 is a fragmentary section showing the interposition of insulation in the rotor body in a plane perpendicular to the rotor axis.
Figs. 13a, 13b and 13c show the profiles of the three vane plates employed in the present construction.

Fig. 14 is an end view of one of the vanes looking along line 14-14 in Fig. 13b.
Fig. 15 shows a vane including a layer of insulation along its medial line.
Fig. 16 is an axial section, similar to Fig. 1, but showing a modified construction.
Fig. 17 is an end view of the unit shown in Fig. 16 looking along line 17-17 in the latter figure. .
Fig. 18 is a view similar to Fig. lOa but showing a modified rotor construction.
Fig. 18a is a fragmentary view looking along line I8a-18a in Fig. 18.
While the invention has been described in connection with certain preferred embodiments, it will be understood that I do not intend to limit the invention to the particular embodiments shown but intend, on the contrary, to cover the various alternative and equivalent constructions included within the spirit and scope of the appended claims.
Turning now to Figs. 1-3 there is shown a compressor-expander unit having a frame 20 formed of two portions 21, 22 arranged face to face and secured together by a circle of bolts 23. Clamped between the two halves - is preferably a thin layer of insulation 24 to which reference will later be made.
Mounted for rotation within the housing is a rotor 30 having a shaft formed of complementary stub shafts 31, 32 respectively supported in bearings 33, 34.
Recessed in the rotor are a series of radially extending vanes 41-46. As brought out in Figs. 2 and 3, the vanes are utilized to form compressor and expander compartments in which the air is positively compressed and then positively permitted to expand, with a heat exchanger interposed to remove the heat of compression, thereby to form a refrigera-tion system. Referring to the port connections shown in Fig. la, air is taken in at a compressor inlet port 51, compressed and heated and then conducted out of the compressor side through a compressor outlet port 52. The heat of compression is removed by a heat exchanger HXl following which the air is fed into an expander inlet port 53. In the expander side the air is expanded, accompanied by a large drop in temperature, with the air exiting from the expander outlet port 54 either directly into a cooled space CS or into a secondary heat exchanger HX2 which cools the space with the help of a fan. Where a secondary heat exchanger HX2 is employed, the system is - referred to as "closed" and sufficient air may be enclosed in the system so that the pressure in the secondary heat exchanger, and indeed in the entire system, is raised substantially above atmospheric to bring about an improve-ment in thermal efficiency.
In accordance with the present invention the housing has a disc-shaped main cavity with adjacent hub recesses, the main cavity being in the form of a doubly truncated sphere symmetric about a vane axis which is canted at an angleC~ with respect to the shaft axis.
The axial recesses in the housing are defined by concave spherical surfaces concentricaliy opposed. A rotor is provided in the housing having a central portion which is spherical in shape for mating with the concave spherical surfaces, the rotor including an integral Saturn-like ring symmetric about the shaft axis and having outwardly convergent b38 sides of shallow cone shape, the ring extending to the outer wall of the main cavity, thereby dividing the cavity into compressor and expander sides each of circular wedge shape having axially thick and thin portions arranged in complementary fashion.
Referring to Fig. lb, which shows the truncated spherical shape of the main cavity 60, it will be noted that the cavity, or vane, axis, VA, is canted, by an angle with respect to the shaft axis SA, with the ring on the rotor 30 dividing the cavity into a first, or compressor, side 61 and a second or expander side 62. The compressor side 61 has an axially "thick" portion 61T and an axially "thin" portion 61t. The expander side 62 has a complementarily arranged thick portion 62T and a thin portion 62t. It will be understood that the vanes 41-46 (Fig. 2) rotate jointly in the sides 61, 62, defining the compartments therein which undergo positive increase and positive decrease in volume as the rotor rotates. For the purpose of mounting and sealing the rotor, the main cavity 60 is provided with opposed spherical recesses 63, 64. The outer spherical surface of the main cavity is indicated at 65.
More detailed attention will next be given to the construction of the rotor 30 which is mounted in the disc-shaped space 60 and which mates with the spherical recesses 63, 64, reference being made to Figs. 7-10 inclusive. The rotor has a central spherical portion 70 having spherical surfaces 71, 72 on the compressor and expander sides, respectively, which mate with the concave spherical surfaces 63, 64 previously referred to. Extend-ing outwardly from the spherical portion 70 is an integralSaturn-like ring 73 of trapezoidal cross section and of 3~
symmetrical, or isosceles, shape presenting a circular band 74 at the periphery lying in a spherical locus and which may be grooved for labyrinth sealing is symmetrically distributed about the shaft axis and has sides of shallow conical shape which are inclined, with respect to a transverse plane 75, by an angle which equals the canting angle (Figs. 1, la and 3) between the vane and shaft axes.
In other words, the included angle of the trapezoid is double the angle ~ . As a result, the sides of the ring engage, and conform to, the wall of the vane cavity at 180 positions along respective lines of contact defining regions of zero thickness of the sides 61, 62 of the main cavity 60.

For the purpose of accommodating the vanes 41-46, the rotor body 30 is formed with radially extending slots 81', 86'which are arranged in diametrical pairs aligned with the shaft axis SA, the diametrical slots defining rotor sectors 81-86. In carrying out the invention the rotor body is provided with a solid core which occupies an offset position at one end leaving the major portion of the body hollow at the center for the crossing of the rotor vanes to be described. The solid offset core, indicated at 90, and the adjacent typical slot 81, 84 may be formed by taking a total of three cuts, thereby forming a slot of C-shaped profile, two axial cuts 91, 92 (Fig. lOa) and a third, or transaxial, cut 93. This leaves a cantilevered end portion 94 for each of the sectors. The cantilevered ends are embraced by a cap 95, integral with the stub shaft 32, and which is held in place by screws 96. At the "core" end of the rotor body a cap 97, integral with the stub shaft 31, is held in place by screws 98.

9~

In accordance with the present invention the vanes have a profile substantially corresponding to the profile of the truncated spherical main cavity, the vanes being provided in opposed pairs integrally connected together in a "dumbbell" shape having a relatively narrow neck which is axially offset, the paired vanes being preferably formed of a single plate of metal and with the necks between cooperating vanes being offset by different amounts to permit crossing of one another at the center of the rotor body. Referring to Figs. 1 and 13, the three vane plates, each formed integrally from flat plate of metal and indicated at 101, 102 and 103, are of reduced section at the center to form necks 104, 105 and 106 which, as shown in Fig. 1, are all accommodated - side by side at the center of the rotor body.
In accordance with one of the aspects of the invention each vane has a spherically shaped tip surface having a radius R equal to that of the truncated sphere together with lateral edges lying in the locus of a cylinder with a radius equal to T/2, where T is the thickness of the truncated sphere. Each vane also has a thickness of at least t = T sin ~ , where ~ is the degree of cant of the truncated sphere axis relative to the shaft axis. This relationship can be verified in Fig. 14 which shows the cross section of a typical vane having a width dimension of T where T is the thickness of the main cavity.
By making the vane thickness t at least equal to T sinc~ , there will be assurance that constant clearance will exist along the wall of the main cavity in spite of the relative twisting of the vane in the cavity which occurs during the course of rotation about the two axes.

In accordance with one of the aspects of the invention each of the vane tips is vented to the center of the rotor by a vent opening 107 which communicates with a recess 108 bounded by a land 109. This insures balanced end-pressures on the vanes.
It is a further feature of the present invention that each of the vanes is laterally extended to form shoulders 111, 112 which are spherically surfaced for mating with the concave spherical surfaces 63, 64 in the cavity. Such engagement keeps the vanes centered during the course of rotation so that the vane tips have a running clearance with respect to the outer spherical wall of the main cavity.
Having understood the construction of the housing, rotor and vanes, it is one of the features of the present invention that the ports include arcuate grooves on the side walls of the main spherical cavity 60, the grooves being opposite the ring portion of the rotor. The shape of the grooves, and their phasing, for the compressor and expander sides of the machine can be understood by reference to Figs. 4 and 5 respectively.
Taking first the compressor side, Fig. 4, it will be noted that the inlet port 51 is arcuately extensive lying in advance of the thickest portion of the wedge-shaped space 61 (see Fig. lb) while the output port 52 is relatively concentrated and located just prior to the thinnest portion of the wedge. In operation, as a chamber defined between vanes 41, 42, for example, swings past the long arcuate port 51 toward the thick dimension of the compressor side, it sucks in air through the port until it reaches position A where the chamber has its 3~3 maximum volume and at which point communication with the port 51 is about to be cut off. After leaving position A, the chamber progressively moves toward the thin portion of the compressor side, compressing the captive air until position B is reached at which time communication is established with the compressor outlet port 52. By the time posltion C is reached the chamber has squeezed all of its air into the compressor outlet port 52 and, having swung beyond the line of "ring" contact LC, is beginning to expand and fill itself through the compressor inlet port 51 to begin another cycle.
Conversely, the expander side has a relatively concentrated inlet port 53 just following the thinnest portion of the wedge-shaped space 62 (Fig. lb) and has an arcuately extensive outlet port 54 following the thickest portion of the wedge, so that air entering the expander inlet is expanded and cooled for discharge.
Referring to Fig. 5, a typical chamber is illustrated at position A' in the act of being filled through the - 20 expander inlet port 53, the chamber being just prior to the point of cut-off. The chamber, upon rotation of the shaft, proceeds from position A', expanding in volume as it approaches the region of axial thickness, until it reaches position B'. During the movement from A' to B' the air is both expanded and cooled and, at point B', it begins to be discharged through the expander outlet port 54.
The expanded air continues to be discharged - from the outlet port 54 until the chamber reaches position C' at which further escape is cut off and at which the ~39~38 chamber begins to be filled with pressurized air through the expander inlet port 53, thereby completing a cycle.
It is to be noted that the lines of contact LC between the ring portion of the rotor and the wall of the main cavity prevent any direct flow between the related inlet and outlet ports both on the compression and expansion sides.
To summarize, with respect to the circuit diagram shown in Fig. la, a parcel of air enters a chamber through inlet port 51, being completely filled at position A (Fig.
4), and is rotated through positions B and C during which the chamber is reduced in size so that compressed and heated air flows from the outlet port 52. The heat of compression is removed in heat exchanger HXl. The cool but pressurized air flows into the expander inlet port 53 filling a chamber at position A', with progressive rotation into position B' during which the air expands and cools, with the cooled air being discharged into the expander outlet port 54, discharge being completed by the time that the chamber reaches position C'. The air from the -expander outlet port 54 may flow directly into the cooled space CS or may flow through a second heat exchanger HX2, in a closed loop, back to the compressor inlet port 51.
It is one of the features of the present con-struction that the ports extend into the regions 61t, 62t where the wedge-shaped compressor and expander sides are "thin". Since the housing is of cylindrical shape the housing wall at the such regions is relatively thick as shown in Fig. 6, thereby permitting an elbowed right-angled bend in the air flow, with the port being brought ~9~38 out to a radially extending connection while preserving large port cross sections to insure efficient air transfer with a limited degree of throttling or "wire drawing".
It is one of the features of the present invention that the average chamber size is less on the expansion side than on the compression side so that a smaller volume of air will be handled per revolution on the expansion side thereby to compensate for the difference in temperature between the air on the compression and expansion sides and to insure that equal masses of air are handled on a per re,volution basis. Thus, referring to Fig. lOa, the radius r2 of the spherical surface 72 on the rotor (which engages recess 64 in the cavity) on the expansion side is substantially greater than the radius rl of the spherical surface 71 (which engages the spherical recess 63) on the compression side. The greater radius results in smaller chambers on the expansion side. Calculating a specific ratio of r2 to rl required for the transport of equal masses of air per revolution is a matter well within the skill of the art, given the temperature of the air on the two sides which in turn depends upon the heat rate of the heat exchanger HXl under a given set of conditions.
In accordance with a further feature of the present invention, means are provided for supplying lubrication,to both the bearings 33, 34 and the corresponding spherical surfaces 63, 64. As shown in Fig. 1 this is accomplished by providing an axially extending lubricant tube 120 having an inlet fitting 121, the tube extending through clearance openings in the necks of the vane plates and communicating with an axial bore 122 in the core 90 ~39~ 8 and cap 97. Extending from the tube and bore, respectively, are radial passageways 123, 124 leading to the bearings 33, 34. Further annular passageways 125, 126 adjacent the respective rotor end caps conduct lubricant, assisted by centrifugal action, from the bearings to the spherical surfaces 63, 64 where the lubricant provides lubrication for both the spherical surfaces on the rotor and the spherical shoulder surfaces 111, 112 on each of the lateral edges of the vanes.
It is a still further feature of the present invention that thermal insulation is provided to prevent short:circuiting of heat within the machine, that is, to thermally isolate, to large degree, the compressor and expander sides of the machine. The thermal insulation in the housing, indicated at 24 in Fig. 1, lies in a plane which is generally symmetrically positioned with respect to the rotor and perpendicular to the rotor axis.
Similarly it is desirable for a layer of thermal insulation to be provided in the rotor as indicated in Fig. 12, the 2Q insulation lying in a symmetrical position in a plane perpendicular to the rotor axis as indicated at 130, the layers 24, 130 being preferably in alignment with one another. To maintain the two halves of the rotor securely fastened together to form a monolithic structure, axially extending clamping screws 131 are provided as shown in Fig. 12, with the rotor halves being kept in accurate align-ment by locator pins 132. Isolation of the two sides may be still further improved by providing a layer of insulation 13a on the medial line of each vane as indicated at 130a in Fig. 15 or by making the vanes, and if desired the rotor and stator, of low conductivity material such as ceramic or plastic.

3 ~ 8 While it is preferred to machine the necessary vane slots in the rotor body, it will be understood by one skilled in the art that the rotor sectors 91-96 may be separately and economically constructed, for example, - ~ using powder metallurgy, and individually secured to the rotor core 90 by means of suitable machine screws 135 as indicated in Fig. 12. Where such construction is used, the cap 95 (Fig. lOa) provides adequate reinforcement at the cantilevered ends.
It is contemplated, however, that the rotor may be machined to provide two solid cores at the respective axial ends with a through-opening between them and with the diametrically related vanes being made of multi-piece construction with a narrow neck extending through the through-opening.
Thus referring to Figs. 16-18, a modified construction is shown which is distinguished by use of two axially spaced solid cores in the rotor indicated at 90a, 90b with a multi-piece vane construction indicated at 43a, 46a, the remaining elements being identified with corresponding reference numerals plus subscript a. The slots in the rotor body are preferably formed by making a pair of cuts 91a, 92a (Fig. 18) much as in the earlier construction, followed by a plunging cut to produce through-opening 93a (see Fig. 16a). This is done for each pair of slots so that the center of the rotor body is hollow for passage of the necks 104a, 105a, 106a of the respective vane pairs.
A typical vane pair is shown in profile, and in partial section, in Fig. 16. Here it will be noted that the individual vanes 43a, 46a are interconnected by 3~3 a hollow tubular neck member 106a having ends secured in radial openings provided in the vanes. The securing is a matter well within the skill of the art; for example, the neck member 106a may have threads of opposite hand at its ends engaging tapped holes in the vanes, thereby serving not only to structurally integrate the vanes but also to provide a means for precise adjustment of vane length.
By using a pair of solid cores 90a, 90b, one at each end of the rotor, the rotor integrity is improved.
And, if desired, the left-hand stub shaft 32a may be secured to the housing and centrally received in an anti-friction bearing mounted in the core element 90b. The term "having stub shafts", as applied to the rotor, therefore includes any stub shaft employed for rotor support. Also, if desired, the driving stub shaft 31a may be integral with the core 90a. Since the vane necks do not, in the structure of Fig. 16, permit axial place-ment of the lubricant tube, the lubricant tube, indicated at 120a, is preferably offset a short distance from the axis as shown. The term "axially extending" as applied to the lubrication tube thus includes a tube which is offset from the axis of rotation. Otherwise lubrication substantially corresponds with that in the previous embodiment. The port connections, indicated at 51a-54a, are, as shown, somewhat more widely spaced than in the early embodiment, but the radial ports therefor still extend through the "thick" portion of the wall at 180 positions so that the benefit of using a sizeable air passage is retained.

'3~
While the term "air" has been used above to denote the refrigerating medium, and while the use of air is preferred, it will be understood that the term is used in a generic sense to include equivalent gases which do not undergo a change of state within the range of pressure and temperature encountered in the present device.
Also while the invention has primarily application to a device which both compresses and expands air in its respective sides, employing the converse porting illustrated respectively in Figs. 4 and 5, it will be understood by one skilled in the art that porting of the type illustrated in Fig. 4 may be employed on both sides of the machine, thereby converting it into a two-stage compressor, with the ports being serially interconnected to provide the two increments of pressure. Or, if desired, porting of the type illustrated in Fig. 5 may be used on both sides of the machine thereby turning it into a two-stage expander, or motor, with theports, again, being serially connected.
Where the device is employed as a two-stage motor or a two-stage compressor, compensation is still highly desirable, with the radii rl, r3 of the central spherical portion of the rotor being in such ratio, depending upon the temperature differential, as will cause equal masses of air or equivalent fluid to be passed on each side of the machine during each revolution. Accordingly, the term "compressor" side and "expander" side shall be understood to be employed for purposes of identifying the two sides of the central cavity without limitation as to the function thereof.
While the operation has been discussed in connection with air as a single medium, it will be understood 3~
that the operation is not limited thereto and that use of an additive of a type undergoing change of state within the pressure and temperature encountered in the unit. An additive such as water, may be employed, particularly when the system is "closed" as shown in Fig. la, to improve the heat rate and coefficient of performance, cross reference, in this connection, being made to prior U.S. patents 3,913,351 which issued on October 21, 1975 and 3,967,466 which issued on July 6, 1976.
It will be apparent that the objectives of the invention have been amply carried out. Instead of the rapid back and forth movement of the vanes which characterizes the prior construction, the vanes in the present device undergo smooth and free rotational movement about the vane axis, thereby making possible higher rotative 5peeds and greatly reducing noise and vibration, as well as bringing about a reduction in friction. The latter, combined with a reduction in the short circuiting flow of heat between the two sides of the machine improves efficiency as measured in terms of coefficient of performance. The high speed of rotation plus improvement in efficiency make the device capable of operating at exceedingly high heat rates, making the device particularly suitable for use in the heat transfer mode in a winter-summer air conditioning system, for example, of the type disclosed in U.S. patent 4,064,705 which issued December 27, 1977.

, ~

Claims (21)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A rotary machine comprising in combination a housing having means for journalling a shaft therein, the housing defining a disc-shaped main cavity having adjoining hub recesses, the main cavity being in the form of a doubly truncated sphere symmetric about a vane axis which is canted with respect to the shaft axis, a rotor in the housing having axially projecting stub shafts, the rotor including a Saturn-like ring symmetric about the shaft axis, the ring extending to the outer wall of the main cavity dividing the cavity into first and second sides each of circular wedge shape having thick and thin portions arranged in complementary fashion, the ring having radially extending slots generally aligned with the shaft axis to divide the ring into sectors, vanes in the slots, the vanes having a profile substantially corresponding to the profile of the truncated sphere to separate each side into successive chambers which vary cyclically in volume as the shaft rotates, each side having an inlet port and an outlet port in straddling relation to the thin portion thereof and in which the vanes are provided in opposed pairs, the vanes comprising each pair being inter-connected such that the vanes of a pair are connected by at least one narrow neck, with the narrow necks having cooperating axial offsets for interfitting with one another, the lateral edges of the vanes being rounded and the thickness of the vanes being such as to provide substantially constant clearance between the vanes and the sidewalls of the main chamber throughout the course of a rotative cycle.

2. The combination as claimed in claim 1 in which compression and expansion take place in the first and second sides separately, the compressor side having an arcuately extensive inlet port in advance of the thickest portion of the wedge and a relatively concentrated outlet port just prior to the thinnest portion of the wedge so that the air entering the compressor inlet is compressed and heated for discharge, the expander side having a relatively concentrated inlet port just following the substantially thinnest portion of the wedge and having an arcuately extensive outlet port following the substantially thickest portion of the wedge so that the air entering the expander inlet is expanded and cooled for discharge, at least the compressor outlet port and expander inlet port having provision for connecting a heat exchanger therebetween for dissipation of the heat of compression.

3. The combination as claimed in claim 2 in which the spherical radius of the central portion of the rotor is greater on the expander side than on the compressor side to reduce the volume of air on the expander side so that equal masses of air are transported per revolution on the two sides of the device.

4. The combination as claimed in claim 1 in which the vanes comprising an opposed pair are integrally formed as a flat plate.

5. The combination as claimed in claim 1 in which the rotor has six vanes formed by three vane plates.

6. The combination as claimed in claim 1 in which the rotor is formed with diametrically extending slots for receiving the pairs of vanes, the slots being of "C" shape to separate the rotor into sectors which are held together by an integral axially offset core at a first axial end, and which are separate at the second end, a cap for joining the sectors together at the second end, and aligned stub shafts secured to the respective ends.

7. The combination as claimed in claim 1 in which the rotor is formed with diametrically extending slots for receiving the pairs of vanes, the slots separating the rotor into sectors which are integrally joined by cores spaced at the axial ends, and the stub shafts engaging the spaced cores, the vanes comprising a pair being separable for assembly and disassembly with respect to the rotor.

8. The combination as claimed in claim 1 in which the ring has a cross section in the form of an isosceles trapezoid having an included angle equal to double the angle of cant thereby to establish a line of contact with the wall of the main cavity at 180° positions to define regions of zero thickness of the respective sides.

9. The combination as claimed in claim 1 in which the rotor has end caps at its respective ends secured to the sectors of the rotor, the stub shafts being integral with the respective end caps.

10. The combination as claimed in claim 1 in which each vane (a) has a spherical tip surface with a radius R
where R is the radius of the truncated sphere, (b) has cylindrical lateral edges with a radius equal to 1/2T where T
is the thickness of the truncated sphere, and (c) has a thickness at least equal to T sin ? where ? is the angle of cant of the vane axis relative to the shaft axis.

11. The combination as claimed in claim 4 in which laterally projecting shoulders are provided along the lateral edges of the vane plates for engaging the respective spherical surfaces in the housing for maintaining the vane plates centered for rotation in the main cavity.

12. The combination as claimed in claim 11 in which the shoulders on the vanes have presented spherical surfaces.

13. The combination as claimed in claim 1 in which the stub shafts have respective axially spaced bearings to provide support for the rotor, means including an axially extending lubricant tube for conducting lubricant to the bearings, the vane plates having central axial bores for providing clearance for the lubricant tube.

14. The combination as claimed in claim 1 in which the stub shafts have axially spaced bearings to provide support for the rotor, means including an axially extending lubricant tube for conducting lubricant to the bearings, and means defining radial lubricant passages for conducting lubricant from the region of the bearings to the spherical surfaces.

15. The combination as claimed in claim 1 in which the ports include arcuate grooves on the sidewalls of the truncated spherical cavity.

16. The combination as claimed in claim 15 in which the housing is cylindrical about the shaft axis, the canting of the cavity producing axially thick walls at 180° positions corresponding to the thin portions of the wedge shaped compressor and expander sides, the ports having access openings formed in the thick walls.

17. The combination as claimed in claim 1 in which the stator includes a layer of thermal insulation lying in a plane generally symmetrically positioned with respect to the rotor and perpendicular to the rotor axis.

18. The combination as claimed in claim 1 in which the rotor includes a layer of thermal insulation symmetrically positioned in the rotor and lying in a plane perpendicular to the rotor axis.

19. The combination as claimed in claim 2 in which a secondary heat exchanger is connected between the expander outlet port and the compressor inlet port.

20. The combination as claimed in claim 19 in which the amount of fluid in the system is such that the secondary heat exchanger operates under a pressure greater than atmospheric.

21. The combination as claimed in claim 1 in which the tips of the vane pairs each have a recess surrounded by a land surface, and means defining radial passageways in the vanes for establishing communication between the recesses to balance end forces.