US1989552A

US1989552A - Rotary compressor

Info

Publication number: US1989552A
Application number: US705155A
Authority: US
Inventors: Paul E Good
Original assignee: Individual
Current assignee: Individual
Priority date: 1934-01-03
Filing date: 1934-01-03
Publication date: 1935-01-29
Anticipated expiration: 1952-01-29

Description

Jan. 29, 1935.

Filed Jan. 3, 1934 ll Sheets-Sheet 1 4 010 no 'o .0 oofloo Jan. 29, 1935. P. E. GOOD ROTARY COMPRESSOR Filed Jan. 3, 1 934 11 Sheets-Sheet 2 r" Fr llllhl. l

Jan. 29, 1935. P. E. @000 v ROTARY COMPRESSOR Fi led Jan. 3, 1934 ll Sheets-Sheet 3 r Jan. 29, 1935.

P. E. GOOD ROTARY CIOMPRESSOR 11 Sheets -Sheet 4 Filed Jan. 351934 lllllllllllllllflllllllllllllll l l l m Jan. 29, 1935. P. E. GOOD ROTARY COMPRESSOR Filed Jan. 5, 1954 1 1 Sheets-Sheet 5 Jan. 29, 1935 P. E. soon ROTARY COMPRESSOR Filed Jan. 5, 1934 ll Sheets-Sheet 6 QN MWWN Jan. 29, 1935. P E, D 1,989,552

ROTARY COMPRESSOR Filed Jan. 3, I934 11 Sheets-Sheet '7 4 I I I V4 @l f @I 1 Jan. 29, 1935. v P. E. GOOD 1,939,552

ROTARY C OMPRES S OR Filed Jan. 5, 1954 -11 Sheets-Sheet 8 Jan. 29, 1935. P. 5.0000 1,989,552

ROTARY COMPRESSOR v Filed Jan 3, 1954 ll Sheets-Sheet Jan. 29, 1935.

P. E. soon ROTARY COMPRESSOR Filed Jan. 5 1954 11 Sheets-Sheet 11 PauZE $005 Patented jan. 29, 1935 wsasssz' This invention relates to rotary gas compressors, and more particularly to the production of high speed rotary compressors.

Previous devices of this type may be generally divided into three classes: centrifugal compres-- sors, gear pumps and variations of gear pumps, and structures employing sliding vanes.

In centrifugal compressors, since they generate pressure by velocity actions, the pressure is dependent upon the peripheral speed of the impellers, and the limit of pressure a machine can produce is dependent upon its maximum rotative speed. While generally eflicient at large volumes, centrifugal compressors are ineii'icient where the pressure is high in relation to the volume, and particularly where the volume is small. By driving the compressor shaft at high speed through speed increasing gears, improved performance on high pressures and relatively small volumes may be obtained, but among the diiiiculties accompanying such construction are: noise and vibration of the gears, expense of their production and space they occupy, and difliculty of securing adequate strength in the compressor impeller con struction. Furthermore, in centrifugal compressors the pressure generated varies in proportion to the specific gravity of the gas pumped, necessitating with electric motor or standard steam turbine drives the use of step-up gearing or multi-stage compressor construction for the production of relatively high pressures in gases of low specific gravity.

The gear pump type is not emciently usable for compressing gases at pressures exceeding eight to ten pounds per square inch and their slow speed of operation necessitates large physical dimensions that place practical limits on maximum unit capacity. The gear pump type is not a true compressor, but a displacement pump, and any compression taking place, occurs only after the rotor has moved to a position where the charge it carries is in communication with the discharge, and compression is then caused by backward flow from the discharge, producing pulsations. -The large area of rotors exposed to the pressure difference between inlet and discharge creates a heavy unbalanced side load on' the shafts with resulting wear and deterioration, particularly when the pressure reaches the highest practicable limits.

The sliding vane type also is not suitable for high speeds. Rapid oscillation of the vane produces inertia forces of large magnitude, and these inertia effects along with the centrifugal forces set up, are detrimental, causing rapid wear of vane and casing, frequently accentuated by line contact only between vane and casing. Difficulty of securing dynamic balance due to lack of symmetry of rotor, and heavy' lateral loadings on 5 shafts due to the rotor areas exposed to pressure difference between intake and discharge, are com- None of the men faults in this type of blower.

three types of pumps is capable of operation at regulatable internally-generated pressures.

Important objects of the present invention are the provision of a pump which is free from reciprocating parts thus eliminating inertia losses when operated at constant speeds; the provision of a simple pump which when operated'at con-' stant speed is capable of producing a variable output pressure and when operated at variable speeds is capable of producing a desired volume at a selectively variable pressure; the provision of v a rotary pump which is capable'of producing a fixed output pressure without variation in speed, regardless of variations in specific gravity of a gas being pumped; the provision of a pump which is operable either as a simple displacement pump or a compressor; the provision of a perfectly symmetrical rotor permitting operation of the compressor at high speeds; the use of a construction providing balanced pressures across any diameter of the rotor or symmetrical balance of pressures and the provision of a pump whose physical dimensions by reason of the characteristics are small, thus rendering it usable in many locations prohibiting the use of other types of pumps.

foregoing Further and specific objects of the invention are the provision of a compressor structure employing a movable barrier, the construction of which is such that friction losses as a result of card of piston type compressors, and with a high efiiciency.

These and other objects I attain by the construction shown in the accompanying drawings, wherein, for the purpose of illustration, I have shown a preferred embodiment of my and wherein:

invention Rig. 1 is a plan view or? rotary compressor con" struction in accordance with my invention;

Fig. 2 is a side elevation thereof;

Fig. 3 is a vertical sectional view therethrough on line 3-3 of Fig. 1;

Fig. 4 is a section on line -4 oi Fig. 3;

5 is a section on line 5-5 of Fig. 3;

Fig. 6 is a section on line 6-6 of Fig. 3;

Fig. 7 is a developed plan showing the arrangement and construction of the grooves of the rotor in one type of compressor constructed in accordance with my invention, the dash and dot lines illustrating a shifted position of the rotor with relation to the barrier elements;

Fig. 8 is an axial development showing the construction and arrangement of the grooves;

Fig. 9 is a view similar to that of Fig. 7 showing the type of compressor illustrated in Figs. 1 to 6 inclusive;

Fig. 10 is a section showing the relations of the grooves and ports in a construction such as illustrated in the development of Figs. '7 and 8 taken on line 10-10 of Fig. '7;

Fig. 11 is a View showing the relation of the grooves and ports in constructions such as shown in Figs. 1 to 6, taken on line 11-11 of Fig. 9;

Fig. 12 is a side elevation partially in section'of a multi-stage compressor constructed in accordance with my invention;

Fig. 13 is a fragmentary transverse section through the casing of the multi-stage compressor; Fig. 14 is a section on line 14-44 of Fig.13; Fig. 15 is a section on line 15-15 of Fig. 13;

Fig. 16 is a section on line 16-16 of Fig. 15, and

Figs. 17 to 26 are semi-diagrammatic views illustrating modifications of the invention.

Referring now to the drawings, and more. particularly to Figs. 1 to 11 thereof, the compressor comprises stationary and movable elements, of which the stationary element is at present illustrated in the form of a cylindrical casing having bearings 11 at its ends for the reception of a rotor shaft 12. The stator is preferably interiorly lined with anti-friction metal, as indicated at 13 and the rotor 14 secured to the shaft 12 has a rotating fit therein. The rotor has formed therein spirally-extending grooves which, in Figs. 1 to 11, are shown as two in number and symmetrically arranged in the rotor as will be rendered obvious by an inspection of thedevelopments shown in Figs. 7 to 11.

The casing mounts in slots 16, which are diametrically opposed or symmetrically spaced from one another, rotatable barrier elements which are shown as two in number and indicated at 17 and 18, each barrier element comprising a plurality of lobes 19 each constructed to fit the grooves 15 with the slightest possible clearance throughout the length of these grooves. Each groove comprises a geometric figure generated by the contour of a lobe of the barrier when the barrier is arranged to intersect the rotor, and the barrier and rotor move at constantly proportional speeds. These lobes may take on a multiplicity of forms, being shown as circular in certain of the figures and as involutes in others of the figures, (see lobes 19-a Figs. 21 and 22). Obviously, the form of the grooves will likewise vary with a variation in the form of the barrier lobe, as will be rendered obvious by a comparative inspection of Figs. 18 and 22 where the grooves 15 and 15a are generated by circular and involute lobes respectively. The groo es are each disposed .at an menses to the direction of rotation; that is to say, opposite ends or" the grooves are displaced from one another as regards the plane of movement thereof during rotation of the rotor. Therefore, the action of the lobes in the grooves is similar to that of the teeth of a worm gear operating in a worm although there is no necessary direct similarity to the contour form of teeth of worm gears. If the rotor 14 be rotated without any external driving of the

barrier elements

17 and 18, the barrier'elements may be driven therefrom and the several lobes will act to completely block at all times one or both of the grooves. Furthermore, while I have illustrated two grooves and two barrier elements and a symmetrical arrangement of these parts, it is obviously possible to change the number of either or both and to depart from symmetrical spacing if so desired.

It must be noted that the grooves are preferably disposed in the circumference of the rotor, and that the grooves should preferably have a circumferential length greater than the distance between adjacent barrier elements. The reason for increased length of the grooves will immediately become obvious when it is pointed out that in a unit having two barriers and two grooves with the rotor rotating at a speed of 3600 R. P. it would only require 1/120 of a second for a given point on the rotor to pass from one to the other of the barriers. The permissible intake period to the groove is, thus, extremely short and the extension of the groove permits an extension of the filling time which will materially increase efficiency and reduce the pressures required at the intake.

The barrier elements act primarily as a means for expelling fluid from the grooves of the rotor, which fluid may be introduced to these grooves in any suitable manner. In Figs. 1 to 11 the casing wall is shown as provided with intake ports 20 and discharge ports 21, each port being illustrated as a group of openings, adjacent marginal edges of the groups being disposed at substantially the same angle to the axis of the rotor as the side edges of the grooves. It is not, however, essential that the ports be disposed in the stator, for these ports may, obviously, be arranged in any manner which will permit of proper intake and discharge of fluid. In Fig. 19, intake ports 20-a are formed in the rotor and communicate continually with one end of the groove and in Fig. 20 both intake and discharge ports 21a are formed in the rotor. In the construction of Fig. 20, however, where it is desired to employ the pump as anything other than a displacement pump, it is practically essential that valving be resorted to as a means for controlling the discharge as shown in Figs. 23 and 24 and hereinafter more particularly described. In Figs. 25 and 26, the barrier element 18-a has the lobes 19-b thereof provided with ports 19c. It will be obvious that in the constructions shown in Figs. 23 to 26 inclusive, the question of whether the ports illustrated constitute intake or discharge ports depends entirely upon the direction of rotation of the rotor. In each case, with the direction ,of rotation as illustrated, the ports constitute discharge ports. If, however, the direction of rotation be reversed, these ports become intake ports. In the construction of Figs. 25 and 26, if the ports 19-c be exhaust ports and it is desired to employ the pump as anything other than a displacement pump, valving one form of which is hereinafter more particularly described must be resorted to. Likewise,

it will be obvious that in Figs. 25 and 26 by simply thickening the barrier elements, porting as illustrated at 19-c can be provided at both faces, thus controlling bothint'ake and discharge.

Under ordinary circumstances, the disposition of the intake ports is not a material matter, it being, however, preferred that these ports be so disposed that intake to the grooves starts immediately upon passage of .the leading ends of the grooves by a barrier in order to prevent vacuum efiects. v

The arrangement of intake and discharge ports, and of the valves associated therewith, if such are provided, may be either such that exhaust starts immediately upon engagement of the barrier element with the groove and cessation of intake to the groove or is delayed for a predetermined sector of rotation after the barrier element has engaged the groove to block the same. In the former instance, the pump will act simply as a displacement or circulation pump and no pressure will be generated, while in the latter instance the barrier acts to compress the fluid in the groove and generate pressure dependent upon the extent of such sector. Figures 7 and 8 illustrate developments of a simple compressor such as shown in Figs. 1 to 6. In these figures the exhaust ports 21 are so disposed that the barrier lobe 19 has been in engagement with the groove for a sector of rotation following engagement of the barrier and discontinuation of communication with the intake ports 20 during which the edge of the groove adjacent the exhaust ports 21 is moved axially of the casing through a distance X. Therefore, fluid discharged from a groove by the barrier to ports 21 will be under compression. Fig. illustrates clearly the axial movement necessary before the exhaust ports 21 are opened, the arrow of this figure indicating the direction of movement of the groove.

In Fig. 9 a development is shown where the exhaust ports are immediately opened after discontinuation of intake and blocking by the barrier and, accordingly, there will be no compression.

Fig. 11, which is a similar section to that of Fig. 10 but made on the type of construction diagrammed in Fig. 9, clearly illustrates the fact that there will be no compression since the exhaust ports will be open to immediately permit flow of fluid therethro'ugh. It also renders obvious the fact that by use of a valve V for determining thepoint of initial opening of the exhaust ports 21, this structure can be made to operate as the structure shown in Fig. 10 for with the valve V in its dotted line position, substantially the same degree of compression is provided as is illustrated in Fig. 10. The valve V can be'operated in any suitable manner. Obviously, by simply displacing the leading edge of the port 21 of Fig. 11 to the right, the valve V instead of acting to convert a displacement pump to a pressure generating pump will act to convert a low pressure pump to one of higher pressure.

The constructions so far discussed are, obviousl capable of use with a greater number of grooves, a different number of barriers, different relative diameters, and a different number of lobes per barrier than illustrated. Due to symmetrical arrangement of rotor grooves and of barriers and ports in the design shown any fluid pressure occurring at one side of the rotor is duplicated at a point diametrically opposite and in the same axial position. In general, complete symmetry and balance of pressure surrounding the rotor as well as exact physical symmetry of the rotor for dynamic balance are characteristics that can be maintained with many variations of groupings of the essential parts. Utilization of those qualities is desirable for the highest form of development of the device although not essential for all cases. As previously pointed out, in operation at high speeds it is advantageous to utilize grooves of greater circumferential length than the distance between consecutive barrier elements in order that increased duration of inlet periods may be secured.

Valving, hereinbefore referred to,- may obviously be conveniently employed in a number of instances and for a variety of purposes. I have hereinbefore pointed out that valving may be utilized with the exhaust ports to determine whether the pump operates simply as a' circulation or displacement pump or acts as a compressor or to determine the extent of compression occurring in a compressor. Under these circumstances, the valve is shifted to determine the point of initial effective opening of the exhaust with respect to the relative positions of the barrier and groove. Under some circumstances, as for example when it is desired to utilize the structure in the reduction of pressures or delivery at pressures lower than those which would normally result with a full intake, it may likewise become necessary to control the intake port to determine the amount of fluid admitted to each groove. In this case the valve preferably acts to cut off the final period of normal communicatio as suggested by the valve V of Fig. 9.

In the type of construction particularly shown in Figs. 1 to 6, the relation of the grooves and ports is as that in the development of Fig. 9; that is to say, the grooves have the same axial width as the spacing between. adjacent edges of the inlet and exhaust ports and in this construc-' tion a valve 24 is provided slidably seating upon the exterior of the stator wall by sliding engagements of lugs 25 upon its' outer face against suitable supports 26 formed on the outer wall of the exhaust chamber 27. Means are provided such as suitably guided rods 28 having forks 29 for engaging the valves for shifting the valves to the desired position. In the present illustration, the rods 28 are disclosed as connected by a yoke 30 manipulated through an adjustment wheel 31.

In the type of construction particularly shown in Figs. 1 to 6 the rotor is illustrated as driven by the synchronous motor 32 affording a uniform speed of operation; The

barrier elements

17 and 18 are likewise driven and at a speed proportionate to the speed of rotation of the rotor. In the present instance, the shafts 33 of the barrier elements are extended and directly connected to synchronous motors 34, thesemotors being so mounted, as generally indicated at 35, that they may be rotatablyadjusted about their axes. Driving of the barrier elements will relieve contact'pressure and friction engendered where these elements are driven by the rotor and by use of the adjustable synchronous motors or other suitable drive, including a corresponding adjustment, the barriers may be maintained at such position that all friction is substantially eliminated.

While synchronous motors have been particularly specified as a means, for operating the shafts of the barrier elements, obviously other methods can be conveniently employed. In Fig. 1'7 the use of fluid motors for this purpose is suggested; while in Figs. 19 and 20 the barrier shafts are driven directly from the rotor shaft. Where fluid motors are employed as a propelling means, these motors need only supply suil'icient torque to (iii relieve the rotor of the driving efiort necessary to rotation of the barrier elements.

Fu'rthermore'while the barrier shafts in Fig 1 to 11 have been disclosed as parallel to the direction of motion of the rotor, this arrangement need not be adhered to, for any angle can be adopted which is deemed desirable. In Figs. 17 and 16 the barrier shafts 33a are disclosed as being parallel to the adjacent grooves of the rotor. it will be noted that while in an arrangement in which the barrier shafts are parallel to the direction of motion of the rotor the edge walls of the barrier elements are substantially fiat, in an arcrangement such as shown in Figs. 17 and 18 the edge walls must be distinctly rounded. For this reason, the arrangement of barrier shaft parallel to direction of rotor motion is probably preferable.

The relatively small diameter and the form of the rotor as well as of the space inwhich it rotates are conducive to low windage losses. The bearing losses are also low, since symmetrically balanced pressures surrounding the rotor make possible its utilization of power supplied as pure torque without unbalanced lateral reactions, and small bearings can be used carrying practically rotor weight only. In comparison the barriers require a very small amount of power, since they preferably revolve at less speed than the rotor and their hearing and windage losses are low. Inlet and discharge port losses are a minimum. With high rotative speed and the resultant small physical dimensions of a unit for a given capacity, the leakage losses occur ring in a unit of this construction can be kept to a low value. These features permit of the realization of high efficiencies.

In Figs. 12 to 16 I have illustrated a threestage compressor constructed in accordance with my invention, the low, intermediate, and high pressure stages being generally designated by the characters A, B and C. The arrangement employed in this compressor, as to each stage, is identical with that just described in connection with Figs. 1 to 6 insofar as the rotor grooves 36 and barrier elements 37 are concerned and needs no further description. The rotor grooves of the stages B and C are: each reduced in capacity with relation to the grooves of the preceding stage to compensate for reductions in volume through compression in the preceding stage, and the associated ports of the stator 38 are proportionately sized. The exhaust ports 39 of the stages A and B are each in direct communication with the intake ports 40 of the succeeding stages B or C. The

valves

41, 42 and 43 controlling the exhaust ports of the stages A, B and C have each secured to the lugs 44 thereof a headed pin 45 between the head of which and the lug 44 thereof are arranged in the order named a fork 46 and a spring 47, which spring normally maintains the fork in engagement with the head 45 but permits yielding under certain circumstances, as hereinafter set forth. Each fork is a portion of an ensemble 48 sliding up n a suitable guide 49 in the valve chamber 50. Each en'- semble comprises, in addition to the fork, a sleeve 51 surrounding the guide 49 and a valve 52 secured to this sleeve. The valve 52 controls communication between

ports

53 and 54 of the valve chamber, port 53 being in communication with the inet port of the associated stage, while port 54 is in communication with the exhaust port of the same stage. The ensemble sleeve is grooved at 55 for co-action with a shifting fork 56, which messes shifting fork is pivoted upon a suitable pivot pin 5*. and is equipped with a roller 56 co-acting with a cam 59. Cam 59 is common to all stages and is actuated through a suitable push rod 66. The cam 59 has slots 61 in which the rollers operate, these slots being offset intermediate their ends with an angular ofiset as indicated at 62. The angular ofiset comprises a means for transferring the roller from one end to the other of the slot and these angle ofifsets are so disposed that the forks 56 of the stages A, B and i) are successively actuated to move the associated valve to the left in Fig. 15. In Fig. 16, the push rod is at an intermediate stage of operation, the valve 41 of the stage A being in operative position and the valve 52 of this stage being disposed to prevent communication between the exhaust and intake of the stage. At the stage B, the valve 42 is partially shifted to its inoperative position and the valve 52 of this stage has not as yet placed the exhaust and intake of the stage in communication; while at stage C both of the

valves

43 and 52 are shifted. It will be noted that when the valve of the stage has reached a predetermined position representing a maximum exhaust opening, the projecting portion of the headed pin 45 engages a suitable stop 63, after which time the valve does not partake of any further movements which are imparted to its associated ensemble 48, the fork 46 of the ensemble sliding upon the pin. and compressing the spring 4'7.

It will be obvious that with an arrangement of this sort it is possible to produce a desired pressure which may be either of the pressure of the'stage A, the compounded pressures of the stages A and B, or the compounded pressures of the stages A, B and C. The unloading valves permit the fluid transferred by unloaded stages to recirculate to the intake of that stage so that there is no compression component in these stages. While the barriers have been illustrated in this multi-stage form as disposed in alignment, this is merely for the purpose of illustration as, obviously, it is readily possible to circumferentially displace the barriers of one stage with relation to those of the other, this arrangement affording some economy in space.

Rotor grooves of one stage may likewise be circumferentially displaced with reference to an adjacent stage for the same purpose. Such displacement of the grooves may be made independently' of barrier displacement. Preferably the time of discharge from one stage and time of inlet to the succeeding stage in a multi-stage compressor are arranged for a minimum pressure variation in the space that provides interstage communication.

Referring now more particularly to Figs. 23 and 24, these'figures disclose valve ports 64 extending through the wall of the rotor to the interior thereof and, likewise, illustrate valving to control such a port. In the present instance, a stationary housing 65 is shown as interiorly fitting the rotor, which housing has ports 66 for communication with the ports 64 at predetermined points for co-action with the ports 64 of the rotor through predetermined sectors of rotor rotation. Rotatably adjustable within the casing is a valve element 6'7 for co-action with the ports 5 66 and it will be obvious that byadjustment of this valve element the duration of the sector of communication may .be adjustably determined.

aesaasa ports and with this rotation reversed they become intake ports. The valve may be rotated in any suitable manner being at present illustrated as having a worm segment 68 connected thereto and engaged by a worm 69, the shaft 70 of which projects from the casing.

In Figs. and 26, wherein the several lobes of the rotor are pocketed at 19-0 to form ports, the stator wall has the port 71 for communication with the port of the active lobe. This communication is shown as controlled by a rotatable segmental-shaped valve 72 which, as in the case of the valves previously .discussed, is adjustable as by means of an arm 73 attached thereto and, accordingly, determines the rotative sector through which the port is in communication with a selected groove. As in the case of Fig-24, if rotation is in the direction of the arrow, the port is an exhaust port, and if reversed is an intake port. Obviously, the various. types of porting as illustrated may be employed in conjunction with one another and many variations are possible in the method of valving to obtain variably adjustable intake and exhaust sectors.

Since the construction is otherwise capable of considerable modification without in any manner departing from the spirit of the invention, I do not wish to be understood as limiting myself to the specific arrangements herein disclosed except as hereinafter claimed.

I claim:

1. Ina high speed multi-stage rotary compressor, a rotor having a plurality of groups of symmetrically arranged spiral grooves disposed in circumferential bands, a stator supporting a plurality of rotatable barriers for each group of grooves, said barriers being symmetrically spaced about the rotor and having lobes, the grooves of each stage being generated by the lobes of the associated barriers when the barriers are positioned to intersect the rotor and the barriers and rotor are rotated .at constantly proportional speeds whereby the lobes of said barriers block the grooves of their respective groups during predetermined sectors of rotation of the rotor and traverse the grooves from end to end, ports associated with each group of grooves for the intake of fiuid to and exhaust of fluid from said grooves, the exhaust port of each group communicating with the intake of the succeeding group, the exhaust port means communicating with each groove during at least a portion of that sector of rotation in which the groove is blocked by a barrierlobe.

2. A device as claimed in claim 1 wherein means are provided to determine the rotative position of the rotor at which a given groove first communicates with the associated exhaust port.

3. A device as claimed in claim 1 wherein valves are provided associated with each exhaust port to determine the rotative position of the rotor at which the exhaust port first communicates with the associated grooves of the group, and means are provided for consecutively actuating said valves.

4. A device as claimed in claim '1 wherein valves are provided associated with each exhaust portto determine the rotative position of the rotor at which the exhaust port first communicates with the associated grooves of the group and means are provided for consecutively actuating said valves, and further means are provided to place the exhaust port associated with a given group of grooves in communication with the intake port thereof as the valve associated with the exhaust port of said group is positioned to fully open the exhaust port.

5. In a rotary compressor, a stationary casing having a pair of diametrically-opposed intake ports and a pair of diametrically-opposed exhaust ports, the intake ports being axially spaced from the exhaust ports, a rotor fitting the casing and having a pair of symmetrically-disposed spiral grooves, and a pair of diametrically-opposed movable barriers carried by said casing and having lobes blocking said grooves from end to end as the rotor is rotated, an intake and an exhaust port being disposedv between the barriers at each having a pair of symmetrically-disposed spiral grooves, a pair of diametrically-opposed movable barriers carried by said casing and having lobes blocking said grooves from end to end as the rotor is rotated, an intake and an exhaust port being disposed betweenthe barriers at each side of the casing whereby the grooves successively c'o-act with said ports, and valve means operable .to increase the effective axial spacing of the'in-= take and exhaust ports.

8. A device as claimed in claim 7 wherein the grooves have an axial width less than the axial spacing of the ports.

9. In a rotary compressor, a stationary cas ing having a pair of diametrically-opposed intake ports and a pair of diametrically-opposed exhaust ports, the intake ports being axially spaced from the exhaust ports, a rotor fitting the casing and having a pair of symmetrically-= disposed spiral grooves, a pair of diametricallyopposed movable barriers carried by said casing and having lobes blocking said grooves from end to end as the rotor is rotated, an intake and an exhaust port being disposed between the barriers at each side of the casing whereby the grooves successively co-act with said ports, and valve means operable to increase the eflective axial spacing of the intake and exhaust ports and to place the intake and exhaust ports in communication with one another.

10. In a rotary compressor, a stationary .casing having a pair of diametrically-opposed intake ports and a pair of diametrically-opposed exhaust ports, the intake ports being axially spaced from the exhaust ports, a rotor fitting the casing and having a pair of symmetrically disposed spiral grooves, and a pair of diametrically-opposed movable barriers carried by said casing and having lobes blocking said grooves from end to end as the rotor is rotated, an intake and an exhaust port being disposed between the barriers at each side of the casing wherebythe grooves successively co-act with said ports, said grooves each extending about the rotor through more than degrees.

11. In a multi-stage rotary compressor, a rotor having a plurality of longitudinally-spaced pairs of symmetrically-disposed spiral grooves therein, a casing surrounding the rotor and having a pair of rotatable barriers for each pair of grooves, the barriers associated with each pair of grooves being circumferentially displaced from one another through degrees having lobes blocking said. grooves and traversing the grooves from end to end as tr e rotor is rotated, the casing having intake and exhaust ports for each pair of grooves, said intake and exhaust ports being axially displaced from one another whereby the grooves successively co-act with said ports, the grooves of each pair being of the same capacity, the grooves oisucceeding pairs being reduced in capacity with relation to the grooves of the preceding pair, and a controllable connection between the exhaust port associated with each pair and the intake port of the succeeding pair.

12. In a rotary compressor, a casing, a rotor having a rotating fit in said casing and having a plurality of spirally extending grooves symmetrically arranged in a circumferential band, a plurality of rotatable barrier elements symmetrically arranged about the rotor and supported by the casing, said barrier elements having lobes to successively block said grooves and traverse the grooves from end to end as the rotor is rotated and ports to permit intake of fluid to and discharge of fluid from said grooves, said ports being axially spaced to communicate with opposite ends of the grooves and being in communication with each of said grooves during a portion only of that period of rotation of the rotor when the groove is blocked by an associated barrier lobe, the barrier elements being circumferentially spaced a distance less than the circumferential length of the grooves.

13. In a high speed rotary pump, a rotor having a plurality of spiral grooves symmetrically arranged in a circumferential band, a stator supporting a plurality of symmetrically arranged r0- tatable barriers having lobes, said grooves being generated by said lobes when the barriers are positioned to intersect the rotor and the barriers and rotor are rotated at constantly proportional speeds whereby in operation of the pump the lobes of the barriers block said grooves during predetermined sectors of rotation of the rotor during which the lobes traverse the grooves from end to end, port means for intake of fluid to and exhaust of fluid from said grooves, the exhaust port means communicating with each 4 groove during at least a portion of that sector of rotation in which the groove is blocked by the lobes.

1a. A device as claimed in claim 13 wherein means are provided to adjustably determine the rotative position oi the rotor at which the groove first communicates with the exhaust port means.

15. A device as claimed in claim 13 wherein means are provided to adjustably determine the rotative position oi the rotor at which the groove finally communicates with the intake port means.

16. A device as claimed in claim 13 wherein means are provided to adjustably determine the rotative positions of the rotor at which the groove first communicates with the exhaust port means and finally communicates with the intake port means.

17. In a high speed rotary pump, a rotor having a plurality of spiral grooves symmetrically arranged in a. circumferential band, a stator supporting a plurality of symmetrically arranged rotatable barriers having lobes, said grooves being generated by said lobes when the barriers are positioned to intersect the rotor and the barriers and rotor are rotated at constantly proportional speeds whereby in operation of the pump the lobes of the barriers block said grooves during predetermined sectors of rotation of the rotor during which the lobes traverse the grooves from end to end, port means for intake of fluid to and exhaust of fluid from said grooves, the exhaust port means communicating with each groove during the latter portion only of that sector of rotation in which the groove is blocked by the lobes.

18. A device as claimed in claim 17 wherein means are provided to adjustably determine the rotative position of the rotor at which the groove first communicates with the exhaust port means.

19. A device as claimed in claim 17 wherein means are provided to adjustably determine the rotative position of the rotor at which the groove finally communicates with the intake port means.

20. A device as claimed in claim 17 wherein means are provided to adjustably determine the rotative positions of the rotor at which the groove first communicates with the exhaust port means and finally communicates with the intake port means.

21. In a high speed rotary pump, a rotor having a plurality of spiral grooves symmetrically arranged in a circumferential band, a stator supporting a plurality of symmetrically arranged ro tatable barriers having lobes, said grooves being generated by said lobes when the barriers are positioned to intersect the rotor and the barriers and rotor are rotated at constantly proportional speeds whereby in operation of the pump the lobes of the barriers block said grooves during predetermined sectors of rotation of the rotor during which the lobes traverse the grooves from end to end, port means for intake of fluid to and exhaust of fluid from said grooves, the exhaust port means communicating with each groove during at least a portion of that sector of rotation in which the groove is blocked by the lobes, the intake means being formed in the stator.

22. A device as claimed in claim 21 wherein means are provided to adjustably determine the rotative position of the rotor at which the groove first communicates with the exhaust port means.

23. A device as claimed in claim 21 wherein means are provided to adjustably determine the rotative position of the rotor at which the groove finally communicates with the intake port means.

24. A device as claimed in claim 21 wherein means are provided to adjustably determine the rotative positions of the rotor at which the groove first communicates with the exhaust port means and finally communicates with the intake port means.

25. In a high speed rotary pump, a rotor having a plurality of. spiral grooves symmetrically arranged in a circumferential band, a stator supporting a plurality of symmetrically arranged rotatable barriers having lobes, said grooves being generated by said lobes when the barriers are positioned to intersect the rotor and the barriers and rotor are rotated at constantly proportional speeds whereby in operation of the pump the lobes of the barriers block said grooves during predetermined sectors of rotation of the rotor during which the lobes traverse the grooves from end to end, port means for intake of fluid to and exhaust of fluid from said grooves, the exhaust port means communicating with each groove during at least a portion of that sector of rotation in which the groove is blocked by the lobes, the exhaust port means being formed in the stator.

26. A device as claimed in claim 25 wherein means are provided to adjustably determine the rotative position of the rotor at which the groove menses first communicates with the exhaust port means.

27. A device as claimed in claim 25 wherein means are provided to adjustably determine the rotative position of the rotor at which the groove finally communicates with the intake port means.

28. A device as claimed in claim 25 wherein means are provided to adjustably determine the rotative positions of the rotor at which the groove first communicates with the exhaust port means and finally communicates with the intake port means.

29. In a high speed rotary pump, a rotor having a plurality of spiral grooves symmetrically arranged in a circumferential band, a stator supporting a plurality of symmetrically. arranged rotatable barriers having lobes, said grooves being generated by said lobes when the barriers are positioned to intersect the rotor and the barriers speeds whereby in operation of the pump the lobes of the barriers block said grooves during predetermined sectors of rotation of the rotor during which the lobes traverse the grooves from end to end, port means for intake of fluid to and exhaust of fluid from said grooves,-the exhaust port means communicating with each groove during at least a portion of that sector of rotation in which the groove is blocked by the lobes, the intake port means being formed in the rotor.

30. A device as claimed in claim 29 wherein means are provided to adjustably determine the rotative position of the rotor at which the groove first communicates with the exhaust port means.

31. A device as claimed in claim 29 wherein means are provided to adjustably determine the rotative position of the rotor at which the groove finally communicates with the intake port means.

32. A device as claimed in claim 29 wherein means are provided to adjustably determine the rotative positions of the rotor at which the groove first communicates with the exhaust port means and finally communicates with the intake port means.

33. In a high speed rotary pump, a rotor having a plurality of spiral grooves symmetrically ar-- ranged in a circumferential band, a stator supporting a plurality of symmetrically arranged rotatable barriers having lobes, said grooves being generated by said lobes when the barriers are positioned to intersect the rotor and the barriers and rotor are rotated at constantly proportional speeds whereby in operation of the pump the lobes of the barriers block said grooves during predetermined sectors of rotation of the rotor during which the lobes traverse the grooves from end to end, port means for intake of fiuid to and exhaust offiuid from said grooves, the exhaust port means communicating with each groove during at least a portion of that sector of rotation in which the groove is blocked by the lobes,'the exhaust p means being formed in the rotor. -34. A device as claimed in claim 33 wherein means are provided to adjustably determine the rotative position of the rotor at which the groove .first communicates with the exhaust port means.

35. A device as. claimed in claim 33 wherein means are provided to adjustably determine the 37. In a high speed rotary pump, a rotor having a plurality oi spiral grooves symmetrically arranged in a circumferential band, a stator supporting a plurality of symmetrically arranged rotatable barriers having lobes, said grooves being generated by said lobes when the barriers are positioned to intersect the rotor and the barriers and rotor are rotated at constantly proportional speeds whereby in operation of the pump the lobes of the barriers block said grooves during predetermined sectors of rotation of the.

rotor during which the lobes traverse the grooves ,from end to end, port means for intake of fluid of rotation in which the groove is blocked bythe lobes, the intake and exhaust port means being formed in the rotor.

38. A device as claimed in claim 37 wherein means are provided to adjustably determine the rotative position of the rotor at which the groove first communicates with the exhaust port means.

39. A device as claimed in claim 3'? wherein means are provided to adjustably determine the rotative position of the rotor atwhich the groove finally communicates with the intake port means.

40. A device as claimed in claim 3'7 wherein ing a plurality of spiral grooves symmetrically arranged in a circumferential band, a stator sup-' porting a plurality of symmetrically arranged rotatable barriers having lobes, said grooves be- ,ing generated by said lobes when the barriers are positioned to intersect the rotor and the barriers and rotor are rotated at constantly proportional speeds whereby in operation of the pump the lobes of the barriers block said grooves I during predetermined sectors-of rotation of the rotor during which the'lobes traverse the grooves from end to end, port means for intake of fluid to and exhaust of fluid from said grooves, the exhaust port means communicating with each groove during at least a portion of that sector of rotation in which the groove is blocked by the finally communicates with the intake port means.

44'. A device as claimed in claim 41 wherein means are provided to adjustably determine the rotative positions of the rotor at which the groove first communicates with the exhaust port means and finally communicates with the intake port means.

i5. In a high speed rotary pump,- a rotor having a plurality oi. spiral grooves symmetrically arranged in a circumferential band, a stator supporting a plurality of symmetrically arranged rotatable barriers having lobes, said grooves being generated by said lobes when the barriers are positioned to intersect the rotor and the barriers and rotor are rotated at constantly proportional speeds whereby in operation 01' the pump the s the rotor first communicates with the exhaust port means.

4:7 A device as claimed in claim 45 wherein means are provided to eidjustably determine the tive position of the rotor at which the groove finally communicates with theintake port means.

es. A device as claimed in claim 45 wherein means are provided to edjustably determine the rotative positions of the rotor at which'the groove first communicates with the exhaust port means and finally communicates with the intake port 10 means.

PAUL E. GOOD.