TWO-ROTOR SLIDING VANE COMPRESSOR

Abstract: A two-rotor, sliding member compressor in which both rotors rotate at the same angular velocity and in which the sliding members have flat heads. The compressor has a first end plate located on a first end of the inner rotor and a second end plate located on a second end of said inner rotor; each of the first end plate and the second end plate supports the inner rotor through a set of bearings. The compressor also has a center housing with a circular interior that is eccentric to the inner rotor, the housing being disposed between said first end plate and the second end plate.

Description: Description Two Rotor Sliding Vane Compressor Technical Field A two-rotor, sliding vane compressor in which both ro¬ tors rotate at the same angular velocity and in which the sliding vanes have flat heads. Background Art Sliding vane compressors are well known to those skilled in the art and are disclosed, e.g., in United States patents 5,310,326, 4,384,828, 4,242,065, 4,132,512, 3,877,853, and the like. The disclosure of each of these United States patents is hereby incorporated by reference into this specification. The classical single rotor-sliding vane compressor is one of the oldest type of compressors on the market. The rea¬ son for its early arrival is found in its simplicity of con¬ struction and ease of machining. Its disadvantage is that it must operate at low speeds, except for very small machines, requiring large sized compressors, and its efficiency is not sufficiently high to compensate for its size. As a result, except for the very low capabilities, the classical sliding vane compressor has fallen into disfavor with the arrival of improved machining techniques that has fostered other types of compression devices that were not possible to produce in the early days of the sliding vane compressor. It is an object of this invention to provide a sliding vane compressor which can be operated at a substantially high¬ er speed than prior art sliding vane compressors. It is another object of this invention to provide a sliding vane compressor which, during its operation, will ex¬ perience substantially reduced tip loading on the sliding vanes. It is yet another object of this invention to provide a sliding vane compressor which is substantially more durable than prior art sliding vane compressors. Summary of the invention In accordance with this invention, there is provided a two-rotor, sliding vane compressor in which both rotors rotate at the same angular velocity and in which the sliding vanes have flat heads. Brief description of the drawings The present invention will be more fully understood by reference to the following detailed description thereof, when read in conjunction with the attached drawings, wherein like reference numerals refer to like elements, and wherein: Figure 1 is a sectional view of the interior of a con¬ ventional sliding vane compressor; Figure IA is an expanded sectional view of the sliding vane compressor of Figure 1, illustrating the contact between a vane tip and the housing of such compressor; Figure 2 is sectional view of one preferred embodiment of a two-rotor sliding vane compressor of the invention, il¬ lustrating the bearing suspension of the two rotors in the end plates; Figure 3 is a sectional view, taken along lines 3—3 of Figure 2, of the compressor of Figure 2, illustrating the structure of the vanes and the inner and outer rotors; Figures 4 and 5 are sectional views of another pre¬ ferred embodiment of the two-rotor sliding vane compressor of this invention, illustrating said embodiment in different ang¬ ular positions, the rotor suspensions depicted in Figures 4 and 5 being identical to that depicted in Figure 2. Description of the preferred embodiments The present invention relates to a two rotor compres¬ sor of the sliding vane type so arranged and constructed as to provide an efficient precompression of the fluid in a working chamber prior to its exposure to a high pressure discharge port. The subject compressor is an improved version of the old line, single rotor-sliding vane compressor. It will be illustrated in this specification by reference to two differ¬ ent embodiments which utilize the same inventive concepts. The present invention modifies the classical sliding vane compressor in such a way as to improve both its speed charac¬ teristics and its efficiency. A prior art sliding vane compressor For the purposes of illustration, it is beneficial to compare the present two rotor sliding vane design to the clas¬ sical, single rotor design; the latter design is illustrated in Figure 1. Such a a comparison will demonstrate the advan¬ tages of the two rotor design. Referring to Figure 1, and in the conventional design depicted therein, the sliding vanes 10 are thrown outwardly by centrifugal force as rotor 12 rotates about shaft 14, thereby causing vanes 10 to contact the inner surface 16 of fixed housing 18. Housing 18 is comprised of inlet passage 20 and outlet passage 22. Because the center 23 of rotor 12 and the center 25 of the fixed housing inner surface 16 are eccentric to each other (see Figure IA) , the tip 24 of the sliding vane 10 does not contact the housing in a normal geometric or flush manner. Theoretically, there is only a line contact of the vanes 10 with the housing inner surface 16, and the contact pressure levels are high because of this non-normal relation¬ ship. Moreover, the vane tip 24 wiping velocity is also high, being equal to the tip velocity of the vanes 10 themselves. Because of the high contact pressure and wiping velocities, the classical single rotor compressor depicted in Figures 1 and IA is limited to relatively low speeds except for very small devices, like air tools. The present invention overcomes these unfavorable features by the incorporation of a second rotor. The con¬ struction and operation of the two rotor compressor to achieve these objectives may be understood by reference to Figures 2 and 3. A preferred two rotor compressor of the invention Figure 2 is a cross-sectional view of a compressor 26 taken through the axis of an inner, vane-carrying, rotor 28. Referring to Figure 2, it will be seen that the main support structures for the compressor 26 are end plates 30 and 32 and center housing 34. The inner rotor 28 is supported by bearing 36 into end plate 30 and bearing 38 to end plate 32. In the embodiment depicted in Figures 2 and 3, the inner rotor 28 contains six vane slots, like vane slots 40, and guides six vanes, like vanes 42. As will be apparent to those skilled in the art, the compressor 26 may contain fewer or more vane slots 40 and vanes 42. Thus, a few as two vane slots 40 and two vanes 42 may be used; and as many as about 16 such vane slots 40 and vanes 42 may be used. It is preferred, however, to use from about 4 to about 12 such vane slots 40 and vanes 42. Referring again to Figures 2 and 3, the outer rotor 44 is supported by means of side plate member 46 through bearing 48 to end plate 30 and side plate member 50 through bearing 52 to end plate 32. It should be noted that side plate members 46 and 50 are the support members for the outer rotor 44, but they act as side plates for inner rotor 28. Also , it is to be noted that side plates 46 and 50 and the inner rotor 28 have very limited velocity with respect to each other since the side plates and the rotor are both in motion. Referring again to Figures 2 and 3, and in the pre¬ ferred embodiment depicted, outer rotor 44 has twelve dis¬ charge ports 54. In the embodiment depicted, there are two discharge ports 54 for each vane 42. However, as will be ap¬ parent to those skilled in the art, more or fewer such dis¬ charge ports may be used. It is preferred, however, to use from about 1 to about 2 discharge ports 44 for each vane 42. Referring again to Figures 2 and 3, and in the pre¬ ferred embodiment depicted, outer rotor 44 has six flat sur¬ faces 56. It may be observed that the heads 58 of the six vanes 48 are preferably flat to match the six flat surfaces 56. In general, there will be at leaεt one flat surface 56 for each vane 42. It is preferred that there be one flat sur¬ face 56 for each vane 42. Referring again to Figures 2 and 3, in operation gas (not shown) is drawn in through the housing entrance passage 60 and fills the working pocket volumes 62, 64, 66, 68, and 70 between the vanes 42, the inner rotor 28, and the outer rotor 44, through ports 54. Both rotors 28 and 44 rotate in the di¬ rection indicated by the arrow 74. At some point 76, the housing 34 comes in close contact to outer rotor 44 and the pocket volumes become trapped. As rotation continues, the vo lume of the pockets is reduced, and the gas becomes com¬ pressed. At some point, when the desired pressure level is reached, a port 54 becomes exposed to discharge port 78, and the gas flows out from the working pockets. A small piece 80 of the housing 34 separates the high pressure gas flowing out of port 78 and from inlet port 60. Figures 4 and 5 illustrate another embodiment of the invention; in Figure 5, the inner rotor 82 has rotated 90 de¬ grees in the direction of arrow 84 about shaft 86. As will be apparent to those skilled in the art, the side view of the design of these Figures 4 and 5, which illustrates the support means for the inner and outer rotors, and bearing layouts, is exactly the same as Figure 2 of the first design Although an off-hand observation of the compressor center section of Figures 4 and 5 might lead one to conclude that a different compressor is being depicted, it should be apparent that the compressor of Figures 4 and 5 utilizes the same inventive concepts as employed in the compressor of Figure 3. Thus, both compressors utilize a second outer rotor with internal flats that coact flushly with flat vane heads emanating from a first inner rotor, such coaction being made possible by the rotational synchronization of the inner and outer rotors. In reality, the alternative design of Figures 4 and 5 is but a limiting case of the general configuration in which the entire inner surface of the outer rotor consists of rectangularly arranged flats, and wherein the center inner rotor also becomes rectangular, supporting one vane on each of its opposing ends. Referring to Figures 4 and 5, it will be seen that outer rotor 88 surrounds the inner rotor 82 and is eccentric to it, in a manner similar to that of the design of Figure 3. Inner rotor 82 rotates around shaft 86. The outer rotor 88 is supported by side plates (not shown in Figures 4 and 5) like those side plates 46 and 50 of Figure 2. The outer rotor 88 is comprised of internal flats 90, 92, 94, and 96. Flats 92 and 96 coact with the flat heads of sliding vanes 98 and 100, forcing the two rotors to rotate in synchronization. The four working chambers 102, 104, 106, and 108 coact cyclically with the inlet passage 60 and outlet passage 78, in center housing 34 through ports 110, 112, 114, and 116 in the same manner as depicted in the design of Figure 3. Block 80 of center body 34 separates the high pressure gas in high pressure outlet 78 form lower pressure gas in inlet passage 60. Referring again to Figure 4, working chambers 104 and 102 are ingesting fresh gas from inlet passage 60, chamber 108 is sealed off while the gas is being compressed, and working chamber 106 is delivering gas to discharge port 78. In Figure 5, by comparison, both rotors are advanced 90 degrees counter¬ clockwise and working chambers 106 and 104 are ingesting gas from inlet passage 60, chamber 102 is undergoing compression, and working chamber 108 is delivering gas to discharge passage 78. In the construction of the embodiment of Figures 4 and 5, there preferably is a structural tie between the ends of sliding vanes 98 and 100 to the ends of slide to hold them snug against the ends of the inner rotor block 82. However, for the sake of simplicity of representation, the depiction of this structural tie has been omitted from Figures 4 and 5. In one embodiment, the device of Figures 4 and 5 is utilized as an internal combustion engine. Referring to Figure 3, the centrifugal outward force of vanes 40 reacts with the outer rotor 34 through flat vane heads 58 acting on the outer rotor flat surfaces 56. This flush contact relationship forces both the inner and outer ro tors to rotate at the same angular velocity at all times. The distance vane head 58 oscillates back and forth on rotor flat surface 56 is equal to four times the distance between the centers of rotation of the inner rotor and the outer rotors, for each revolution of the rotors. This distance is equal to about one tenth of the distance that each vane head travels. Hence, comparing the present design to the classical single rotor design, the wiping velocity of the vane tip, for the same size machine, is reduced by about ninety percent. This is a huge advantage. Additionally, the head of the vane 42 can be made to have at least ten times the tip contact area on the flats 56 of the outer rotor 34 as could be attained in a single rotor compressor of the same size. The vanes become "T" or "L" shaped, being much wider at the tip than at the slot position. Hence, the operational advantages of employing the present two rotor design over the classical design are obvious and overwhelming. It will be apparent to those skilled in the art that the advantages discussed for the embodiment of Figure 3 are equally present for the embodiment of Figures 4 and 5. There are several other two rotor vane compressors found in the patent literature, but none of these designs fea¬ ture a synchronization of the angular velocity of the two ro¬ tors. This feature makes it possible to employ a flat head on the inside of the outer rotor that will be in constant normal relationship with the head of a vane from the inner rotor. This also allows for a flat vane head which can be extended to reduce the contact pressure. Moreover, since the position of the outer rotor is tied to the position of the vanes, it is possible and practical to add ports to the outer rotor that act as a valving mechanism with respect to the inlet and out¬ let passage means in the housing that surrounds the rotor. If, as in other designs, the outer rotor is allowed to seek its own speed, depending upon vane tip drag, there is no syn¬ chronization between the vanes and the other rotor, and there¬ fore, it cannot act as a timed valving device. To these skilled in the art obvious changes could be made for particular applications. Crank arms could be em¬ ployed between the side plate member 46 and inner rotor 28 (see Figure 2) to force synchronization of the two rotors if the inertial force of the vanes on the outer rotor flats proved to be insufficient to do the job. The number of vanes could be increased or decreased. Skirts could be added to each end of the vanes to reduce the leakage between them and the side plates with which they coact, or through vanes could be employed. It is also possible to relocate the inlet our outlet passage means into the end plates. It is to be understood that the aforementioned de¬ scription is illustrative only and that changes can be made in the apparatus, in the ingredients and their proportions, and in the sequence of combinations and process steps, as well as in other aspects of the invention discussed herein, without departing from the scope of the invention as defined in the following claims.

Claims: hat is claimed is: 1. A two rotor, sliding vane rotary compressor for compress¬ ing fluid comprising an inner rotor, an outer rotor, means for rotating said inner rotor and said outer rotor at the same angular velocity, and at least one sliding member disposed between said inner rotor and said outer rotor, wherein: (a) said outer rotor is comprised of an inner surface, and said inner surface is comprised of at least one flat portion, whereby, as said inner rotor rotates, said sliding member contacts said outer rotor; (b) said inner rotor is supported by support shafts on each of its ends; (c)said compressor is comprised of a first end plate locat¬ ed on a first end of said inner rotor and a second end plate located on a second end of said inner rotor, wherein each of said first end plate and said second end plate supports said inner rotor through a first set of bearings; (d) said compressor is comprised of a center housing with a circular interior that is eccentric to said inner rotor, said housing being disposed between said first end plate and said second end plate; (e) said outer rotor has a circular exterior that surrounds said inner rotor but is eccentric thereto; and (f) said outer rotor is mounted on a second set of bearings disposed in said first end plate and said second end plate. 2. The compressor as recited in claim 1, wherein said sliding member is a sliding vane. 3. A two rotor, sliding member rotary compressor for com¬ pressing gas comprising an inner rotor, an outer rotor, means for rotating said inner rotor and said outer rotor at the same angular velocity, and at least one sliding member disposed between said inner rotor and said outer rotor, wherein: (a) said inner rotor is comprised of an outer surface, and said outer surface is comprised of at least one flat portion, whereby, as said inner rotor rotates, said sliding member slides on said flat surface on said inner rotor and coacts with said outer rotor; (b) said inner rotor is supported by support shafts on each of its ends; (c) said compressor is comprised of a first end plate located on a first end of said inner rotor and a second end plate located on a second end of said inner rotor, wherein each of said first end plate and said second end plate supports said inner rotor through a first set of bearings; (d) said compressor is comprised of a center housing with a circular interior that is eccentric to said inner rotor, said housing being disposed between said first end plate and said second end plate; (e) said outer rotor has a circular exterior that surrounds aid inner rotor but is eccentric thereto; and (f) said outer rotor is mounted on a second set of bearings disposed in said first end plate and said second end plate. 4. The compressor as recited in claim 3, wherein said sliding member is a sliding vane.

Applicants: CARRIER CORP, CARRIER CORPORATION
Application year: 1996
Main classification: F04C18
IPC codes: F04B1, F04B27, F04C18