US3540816A - Coaxial multi-stage rotory compressor - Google Patents

Description

Nov. 17, 1970 R. s. ALCOLEA 3,540,315

COAXIAL MUL'II-STAGE ROTARY COMPRESSOR Filed Dec. 5, 1968 4 Sheets-Sheet 1 III/l .II/

III I/III III Nov. 17, 1970 R. G. ALCOLEA COAXIAL MULTI-STAGE ROTARY COMPRESSOR 4 Sheets-Sneex 2 Filed Dec. 3, 1968 Caz-s Nov. 17, 1970 R. G. ALCOLEA 3,540,315

COAXIAL MULTI-STAGE ROTARY COMPRESSOR I Fiied Dec. 3, 1968 4 Sheets-5mm s Nov. 17, 1970 R. e. ALCOLEA COAXIAL MULTI-SIAGE ROTARY COMPRESSOR 4 Sheets-Shem Filed Dec. 5. 1968 FIG-5 FIG-6 United States Patent 3,540,816 COAXIAL MULTI-STAGE ROTORY COMPRESSOR Rafael Gil Alcolea, Ximenez de Quesada 17-3", Cordoba, Spain Filed Dec. 3, 1968, Ser. No. 780,809 Claims priority, application Spain, Dec. 5, 1967,

Int. Cl. F041) 13/02 19/02; F04c 1/00 US. Cl. 418-177 16 Claims ABSTRACT OF THE DISCLOSURE A coaxial multi-stage rotary compressor comprising a cylindrical rotor which in turn carries and guides generally axially disposed and spaced reciprocatable blades of constant length, each end of each blade being also guided in reciprocating movement between substantially elliptical surfaces, the blades always remaining in a radial position with respect to said rotor and, therefore, perpendicular to the tangent to the surface of the rotor which is adapted to drive said blades, one stage of said compressor being between an inner side of said rotor and one elliptical surface and another stage of said compressor being between the exterior of said rotor and a second concoidal transformated surface.

This invention relates to a multi-stage compressor and more particularly to a coaxial multi-stage compressor of the rotary type.

Internal combustion engines and thermal engines, in general, include means for compressing, or a compression cycle so that the air supporting combustion with or without fuel incorporated is compressed before ignition. In such engines the compression takes .place either in the same chamber where combustion occurs or it is compressed outside of the combustion chamber by an independent compressor normally called a supercharger. Internal combustion engines of the character described include those which utilize the Otto cycle or are sometimes called four cycle. Other examples include diesel engines of the type used in vehicles or ships. Still other examples include the gas turbines used in airplanes and also in ships.

Compressors used for supercharging are generally not of the reciprocating type because of the high rotational speeds at which they must operate. Because of these high speeds, problems are involved in the utilization of valves usually associated with reciprocating piston type compressors. The compressors which have been used for supercharging are of the rotary volumetric or centrifugal type and the power for driving such superchargers is always supplied by the engine itself in the case of aircraft and surface vehicles. In the case of stationary engines or ship engines, the superchargers may be driven by an auxiliary engine.

In the superchargers of the prior art the compression takes place either in a single stage or in a multi-stage arrangement wherein the compressor shaft is extended so that the stages of the compressor are extended from each other in an axial direction.

In accordance with the instant invention the coaxial arrangement of the multiplicity of stages is such that one stage is about the other and so the shaft of the compressor is not extended. Further, in accordance with the instant invention the arrangement is such that inter-cooling may take place between stages.

Other objects and the nature and advantages of the instant invention will be apparent from the following description taken in conjunction with the accompanying drawings, wherein:

3,540,816 Patented Nov. 17, 1970 FIG. 1 is a schematic illustration of the mathematical principles of a part of the mechanism of the invention;

FIG. 2 is a fragmentary vertical section taken through a portion of the apparatus illustrated in FIG. 3 with arrows showing how air or other medium to be compressed can be brought into the first stage;

FIG. 3 is a vertical section through the coaxial multistage rotary compressor taken at right angles to the axis of the rotor;

FIG. 4 is a vertical section taken at right angles to the section illustrated in FIG. 3 and also including a receiver below the mechanism which is not illustrated in FIG. 3;

FIG. 5 is a fragmentary view partially in perspective and partially in section showing the sealing engagement of a blade with the rotor and also a cooling passage within the blade; and

FIG. 6 is a detail of the end of a blade after removal of the seal at the end of a blade.

The coaxial relatively short shaft multi-stage compressor, in accordance with the invention, consists essentially of three principal parts which may be viewed in FIG. 3. These principal parts are as follows:

(A) The first principal part is an interior stationary body 4 having a generally elliptical interior surface;

(B) An exterior stationary body 3 having a concoidal transformated interior surface; and

(C) The third principal part is the rotor 5 which carries and guides spaced radially disposed sliding blades.

The stationary interior body 4 has its external substantially elliptical surface perfectly machined so that the interior ends of the driven blades can slide thereon with minimum frictional losses and susbtantially without leakage.

The stationary exterior body 3 is also machined to have a substantially elliptical surface which is derived from the external ellipse of the interior body 4 by adding a constant length to the vector radii drawn from the center of that ellipse (i.e. the concoidal transformation of the external curve). The functions which are defined in coordinated polars in the following formulae, are easily representable, derivable and continuous and can, therefore, be industrially mechanized by any modern manufacturing proecss (see FIG. 1).

1 cos 0 sin 0 Internal ellipse:

With the above geometrical formulae which bind the various parameters, representing the semi-axis of the ellipses and the thickness of the guide rotor, in the function of the constructively interesting proportions to which the semi-axis and the thickness should correspond to obtain certain compression relations, both for the first phase as well as for the second phase after due intermediate refrigeration, various axial-biphase compressors can be manufactured for the most varied work conditions and requirements of the engines to which they can be applied.

Further, there can also be included another biphase compressor set located at inner part of the interior body that reproduces identically the multi-stage compression processes being fed by air compressed from the different receivers, thus providing enough upper-pressured air for fluid control.

The simplification of the fluid compression process, together with the opportunity for the practical realization of an intermediate refrigeration, without the run of the compressed fluid in the first phase having to overcome a certain length in function with the admissible losses or the degree of refrigeration required, allow for some very important economies in the fluid compression operation, which can be listed as follows:

(a) Economy of space, as it is an extremely compact unit, depending on its relative dimensions.

(b) Economy and regularity in functioning, as it allows the two air-pressured receivers of the air partially compressed in each phase to be contained in a block.

(c) Flexibility of consumption and application with regard to the various uses, as direct outlets can be taken from each one of the phases, complying, at the same time, with different pressure demands.

(d) Economies derived from the yield increase through the elimination of intermediate losses when transferring the compressed air from one phase to another.

(e) Great increase in the beneficial use of the energy available in the engine through the intermediate refrigeration obtained during the functioning of the compressor between one phase and another, to the benefit of the output of the second phase.

(f) Obtention of high pressures without need of heavy devices, as the resulting differential pressures between its elements partly compensate the resistance demand of the walls and the final compression turns out to be an approximate product of the compression relations of the two superposed phases.

In addition to the aforementioned advantages, there will be others present in the utilization of the invention which will be apparent to those skilled in the art working with the instant invention.

The operation of the coaxial multi-stage compressor will be better understood when reference is made to the drawings as follows:

The two concentric surfaces of the stationary outer and inner bodies 3, 4, determine a continuous cylindrical chamber and delimit a segment of constant length for all the vector radii drawn from the center of the compressor. The cylindrical rotor is of circular section and is concentric with the said elliptical surface, and revolves within the aforementioned elliptical chamber.

The rotor 5 which has internal and external surfaces revolves with respect to the two stationary bodies 3, 4, so that the internal walls of the rotor 5 are at a constant tangent to the major axis of the stationary body 4 and the external walls of the rotor 5 are at a constant tangent with the internal surface of the stationary body 3 through its minor axis.

In accordance with the instant invention, the blades are always directed towards the common center of all the surfaces, in whatever position they are in, they will always be extending in a radial direction and slide between parallel surfaces of the exterior of the stationary body 4 and the interior of the stationary body 3. The blades 10 are each of the same length.

Between each two consecutive blades it will be noted that as the space between the rotor 5 and the body 4 increases, then the space between the rotor 5 and the body 3 decreases.

It is to be understood that the blades may be provided with leakage preventing devices or sealing devices such as may be necessary to avoid fluid losses between each two consecutive spaces separated by the blades 10 and also defined by the interior surfaces of the stationary body 3 and the exterior surfaces of the stationary body 4. See FIG. 5, for example.

The compressed air passing from the space between the rotor 5 and the interior surface of the stationary body 3 may be led through a cooling means or refrigerator which may include a water cooled surface or a fin surface and then the compressed air which has already been cooled may be passed through a passage from which it enters the space between the stationary body 4 and the interior surface of the rotor 5 whereupon the air is once more compressed in a second stage. schematically the illustration in FIG. 3 would show a multi-stage compression in the order of about 1 to 15.

As described above, it is contemplated that the partially compressed air from the first stage will be passed into the space between the stationary body 4 and the interior space of the rotor 5 through a cylindrical passageway in the hollow shaft of the rotor 5. Another embodiment illustrated in FIG. 4, which does not include this hollow shaft, does, however, include a block which is traversed by the conduits through which is passed the partially compressed air of the first stage and also cooling water chamber 1.

In FIG. 4, the rotor 5 is illustrated as being associated with a support bearing 7 and the rotor 5 is adapted to be driven through meshing gears by the pinion 9 mounted on the driving shaft 8.

In both of the described forms pressurized cooling oil is circulated across the contact surface of the block which is formed by inner and outer walls of the rotor 5. This oil fills the chambers disposed in the periphery of the rotor and serves to lubricate the sides of the blades 10 through suitable ports as the blades 10 are carried and guided by the rotor 5.

The blades 10, which are constantly guided in their different positions in relation to the rotor 5, may have friction reducing devices at their ends such as may be afforded by a simple circular elastic surface [O-ring] or tiltable articulated means constantly adaptable to the different slopes of the surface engaged by the end of a blade. The ends of the blades may also be fitted out with housings including draw bands and double pressure arrangements and such arrangements may be situated ad bee in extensions in the blade ends. To take up lateral thrust, similarly other devices of suitable material may be provided for the purpose of supporting and guiding in bearing relation the rotor with respect to the stationary bodies both on the inside and outside.

The interior cooling of the blades 10, apart from the cooled air received immediately with the first admission of air to be compressed and some of the cooling communicated thereto after the first compression stage, is effected, as will be understood by reference to FIG. 5, by passing a liquid or material similar to that used in the hollow parts of inlet and outlet valves in internal combustion engines, through hollow portions of the blades 10.

The regulation of pressures in both receivers 6 and 11 is governed, within the relative values related to a given compressor in accordance with the instant invention, by inlet and outlet valves, guided by gauged springs, which permit the upward and downward movement of pressures in the receivers to be maintained within predetermined tolerances according to special requirements of the surface to which the compressors in accordance with the instant invention are to be put.

When the compressors in accordance with the instant invention are utilized for the purpose of supercharging an explosion or internal combustion engine, in some circumstances it may be desirable that the temperature of the compressed air in the second stage he raised before the supercharged air is passed to the combustion or explosion engine. This raising of the compressed air temperature may easily be effected by an arrangement wherein the outlet pipe of the receiver on its way to the engine inlet is first passed through a section of the engine exhaust gas, whereby the final pressure can be appreciably increased as required. In such circumstances the supercharger may be used in association with the engines of the diesel type, semi-diesel type, or simple Otto cycle engines. or gas turbines. This flexibility in the use of compressors in accordance with the instant invention is extensive and significant.

It will be obvious to those skilled in the art that various changes may be made without departing from the scope of the invention and the invention is not to be considered limited to what is shown in the drawings and described in the specification.

I claim:

1. A coaxial multi-stage rotary compressor comprising a cylindrical rotor which carries and guides generally axially disposed and spaced reciprocatable blades of constant length, a first stage chamber defined by the inner surface of an outer substantially elliptical stator and the outer surface of said rotor, a second stage chamber defined by the inner surface of said rotor and the outer surface of a substantially elliptical inner stator located within said rotor, each end of each blade being guided in reciprocating movement between said substantially elliptical surfaces which have a common center with the center of said cylindrical rotor, each blade being guided by guiding means on said rotor and said elliptical surfaces so that each blade is always radially disposed and perpendicular to tangents to surfaces of the rotor which is adapted to drive said blades, said rotor being kept at a constant tangent with an interior surface of said outer stator and the inner surface of said rotor being kept at a substantially constant tangent with a surface of said inner stator, the blades which are guided by said rotor are delimited in their reciprocatable movement by an inner surface of the outer stator and an outer surface of the inner stator, one stage of said compressor being on the inside of said rotor and another stage of said compressor being on the outside of said rotor, the space between consecutive blades being separated into two compartments in one of which the medium to be compressed is subjected to a decreasing volume and in the other of which the medium is being taken in whereby in an identical radial section the medium may be taken into the inside of the rotor and be compressed on the outside of the rotor and whereby the medium which has received its first compression on the outside of the rotor may be compressed in a second stage on the inside of the rotor.

2. A coaxial multi-stage rotary compressor in accordance with claim 1, in which the medium from the first compression stage is cooled or refrigerated before it is passed to the second stage.

3. A coaxial multi-stage rotary compressor in accordance with claim 1, in which medium from the second stage is passed to a cooling means and the cooled second stage medium is pressure regulated.

4. A coaxial multi-stage rotary compressor comprising a cylindrical rotor which carries and guides generally axially disposed and spaced reciprocatable blades of constant length, a first stage chamber defined by the inner surface of an outer substantially elliptical stator and the outer surface of said rotor, a second stage chamber defined by the inner surface of said rotor and the outer surface of a substantially elliptical inner stator located within said rotor, each end of each blade being guided in reciprocating movement between said substantially elliptical surfaces which have a common center with the center of said cylindrical rotor, each blade being guided by guiding means on said rotor and said elliptical surfaces so that each blade is always radially disposed and perpendicular to tangent to surfaces of the rotor which is adapted to drive said blades, said rotor being kept at a constant tangent with an interior surface of said outer stator and the inner surface of said rotor being kept at a substantially constant tangent with a surface of said inner stator, the blades which are guided by said rotor are delimited in their reciprocatable movement by an inner surface of the outer statorand an outer surface of the inner stator, one stage of said compressor being on the inside of said rotor and another stage of said compressor being on the outside of said rotor, wherein said rotor comprises an inner wall spaced from an outer wall between which is a passage for oil circulation which effects the dual purpose of cooling the spaces immediately adjacent the walls of said rotor and also effects lubrication of the sides of the blades which slides through the rotor walls.

5. A coaxial multi-stage rotary compressor comprising a cylindrical rotor which carries and guides generally axially disposed and spaced reciprocatable blades of constant length, a first stage chamber defined by the inner surface of an outer substantially elliptical stator and the outer surface of said rotor, a second stage chamber defined by the inner surface of said rotor and the outer surface of a substantially elliptical inner stator located within said rotor, each end of each blade being guided in reciprocating movement between said substantially elliptical surfaces which have a common center with the center of said cylindrical rotor, each blade being guided by guiding means on said rotor and said elliptical surfaces so that each blade is always radially disposed and perpendicular to tangents to surfaces of the rotor which is adapted to drive said blades, said rotor being kept at a constant tangent with an interior surface of said outer stator and the inner surface of said rotor being kept at at a substantially constant tangent with a surface of said inner stator, the blades which are guided by said rotor are delimited in their reciprocatable movement by an inner surface of the outer stator and an outer surface of the inner stator, one stage of said compressor being on the inside of said rotor and another stage of said compressor being on the outside of said rotor, the blades being provided with hollow longitudinal and transverse extensions through which a cooling liquid circulates under the influence of the motion imparted by the rotor and the substantially elliptical surfaces which limit the reciprocation of the blades.

6. A coaxial multi-stage rotary compressor comprising a cylindrical rotor which carries and guides generally axially disposed and spaced reciprocatable blades of constant length, a first stage chamber defined by the inner surface of an outer substantially elliptical stator and the outer surface of said rotor, a second stage chamber defined by the inner surface of said rotor and the outer surface of a substantially elliptical inner stator located within said rotor, each end of each blade being guided in reciprocating movement between said substantially elliptical surfaces which have a common center with the center of said cylindrical rotor, each blade being guided by guiding means on said rotor and said elliptical surfaces so that each blade is always radially disposed and perpendicular to tangents to surfaces of the rotor which is adapted to drive said blades, said rotor being kept at a constant tangent with an interior surface of said outer stator and the inner surface of said rotor being kept at a substantially. constant tangent with a surface of said inner stator, the blades which are guided by said rotor are delimited in their reciprocatable movement by an inner surface of the outer stator and an outer surface of the inner stator, one stage of said compressor being on the inside of said rotor and another stage of said compressor being on the outside of said rotor, the first substantially elliptical surface being formed on an inner stator which has provided therein a hollow chamber in the central axial area adjacent the axis of said rotor which hollow chamber houses both the rotor bearings and the feed passages for medium compressed in a stage of the coaxial multi-stage rotary compressor.

7. A coaxial multi-stage rotary compressor including a cylindrical rotor carrying and guiding generally axially arranged spaced blades of constant length, said blades being arranged for reciprocatable movement between substantially spaced exterior and interior elliptical stationary concentric surfaces so that the blades are always radially disposed with respect to the geometric center of said elliptical concentric surfaces, said compressor being characterized in that the cylindrical rotor is constantly in contact, at a portion of its inner surface, with surface portions at the ends of the major axis of the interior elliptical surface, said rotor being constantly in contact, at a portion of its external surface with surface portions at the ends of the minor axis of the exterior elliptical surface, whereby there is created within the rotor a first independent chamber and there is created on the outside of said cylindrical rotor a second independent chamber.

8. A coaxial multi-stage rotary compressor according to claim 7, characterized in that the space between consecutive blades is divided into two compartments by a portion of the cylindrical rotor which has an outer surface and an inner surface.

9. A coaxial multi-stage rotary compressor according to claim 7, characterized in that the space between consecutive blades is delimited by surface portions of said elliptical surfaces and a portion of the cylindrical surfaces of said rotor and by the surfaces of the blades, whereby there is created twice as many compartments as the number of blades.

10. A coaxial multi-stage rotary compressor according to claim 7, characterized in that a radial space between two consecutive blades forms an exterior compartment and an interior compartment and whereby the medium to be compressed may be introduced into the exterior compartment and additionally compressed in the interior compartment.

11. A coaxial multi-stage rotary compressor according to claim 10, characterized in that the medium to be compressed from the first compression compartment is passed to a cooling means and subsequently passed to the second compression compartment.

12. A coaxial multi-stage rotary compressor according to claim 10, characterized in that the medium to be compressed from the second compression compartment is passed to a cooling means and then is pressure regulated.

13. A coaxial multi-stage rotary compressor according to claim 7, characterized in that the space between the inner surface and the outer surface of said rotor provides a passage for circulating and lubricating oil for effecting cooling of said compartments and lubrication of the sides of the blades which slide through the rotor walls.

14. A coaxial multi-stage rotary compressor according to claim 7, characterized in that the blades are hollow so that cooling liquid may be circulated through said hollow blades.

15. A coaxial multi-stage rotary compressor according to claim 7, characterized in that the interior elliptical stationary surface has hollow portions therein wherein are located the rotor bearings and the feed passages for the medium to be compressed including the passages between the first and second compartments.

16. A coaxial multi-stage rotary compressor according to claim 7, characterized in that the interior elliptical element comprises passageways for medium to be com pressed and cooling chambers for effecting inter-cooling.

References Cited UNITED STATES PATENTS 1,666,466 4/1928 Peters 103-136 2,280,272 4/1942 Sullivan 103-136 X 2,371,942 3/1945 Armstrong 103-136 2,521,592 9/1950 McManus 230-158 2,827,857 3/ 1958 Eserkaln.

CARLTON R. CROYLE, Primary Examiner W. J. KRAUSS, Assistant Examiner

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