Patent Publication Number: US-11022118-B2

Title: Concentric vane compressor

Description:
BACKGROUND 
     Vane compressors generally include a stationary or fixed cylinder with a slot for a reciprocating vane. An orbiting cylinder is positioned within the fixed cylinder, and the reciprocating vane (e.g., with a vane spring) is inserted into the vane slot on the outer fixed cylinder, with one end maintaining contact with the smaller orbiting cylinder. The vane provides a barrier between high and low pressure regions within a cylinder cavity formed between the stationary or fixed cylinder and the orbiting cylinder. 
     SUMMARY 
     A positive displacement device includes a first cylinder, a second cylinder disposed within the first cylinder, and a third cylinder disposed around the first cylinder. An interior surface of the first cylinder and an exterior surface of the second cylinder define an inner cavity. An exterior surface of the first cylinder and an interior surface of the third cylinder define an outer cavity. A partition between the interior surface of the first cylinder and the exterior surface of the second cylinder divides the inner cavity into inner regions, and another partition between the exterior surface of the first cylinder and the interior surface of the third cylinder divides the outer cavity into outer regions. The second cylinder and the third cylinder orbit with respect to the first cylinder to create alternating regions of high pressure and low pressure in the inner regions and the outer regions. 
     This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter. 
    
    
     
       DRAWINGS 
       The Detailed Description is described with reference to the accompanying figures. The use of the same reference numbers in different instances in the description and the figures may indicate similar or identical items. 
         FIG. 1  is a perspective view illustrating a positive displacement device in accordance with example embodiments of the present disclosure. 
         FIG. 2  is an exploded perspective view of the positive displacement device illustrated in  FIG. 1 . 
         FIG. 3  is another exploded perspective view of the positive displacement device illustrated in  FIG. 1 . 
         FIG. 4A  is a partial cross-sectional side elevation view illustrating an orbiting cylinder pair with an eccentric journal bearing for a positive displacement device in accordance with an example embodiment of the present disclosure. 
         FIG. 4B  is a partial cross-sectional side elevation view illustrating a stationary cylinder with a vane slot and a journal bearing for a positive displacement device in accordance with an example embodiment of the present disclosure. 
         FIG. 4C  is an exploded isometric view of the orbiting cylinder pair and the stationary cylinder illustrated in  FIGS. 4A and 4B . 
         FIG. 5  is a perspective view illustrating another positive displacement device in accordance with example embodiments of the present disclosure. 
         FIG. 6  is an exploded perspective view of the positive displacement device illustrated in  FIG. 4 . 
         FIG. 7  is another exploded perspective view of the positive displacement device illustrated in  FIG. 4 . 
         FIG. 8  is a cross-sectional end view illustrating a positive displacement device including a first cylinder, a second cylinder disposed within the first cylinder, and a third cylinder disposed around the first cylinder, where the positive displacement device is shown at zero degrees (0°) of shaft rotation in accordance with an example embodiment of the present disclosure. 
         FIG. 9  is another cross-sectional end view of the positive displacement device illustrated in  FIG. 8 , where the positive displacement device is shown at forty-five degrees (45°) of shaft rotation in accordance with an example embodiment of the present disclosure. 
         FIG. 10  is another cross-sectional end view of the positive displacement device illustrated in  FIG. 8 , where the positive displacement device is shown at ninety degrees (90°) of shaft rotation in accordance with an example embodiment of the present disclosure. 
         FIG. 11  is another cross-sectional end view of the positive displacement device illustrated in  FIG. 8 , where the positive displacement device is shown at one hundred and thirty-five degrees (135°) of shaft rotation in accordance with an example embodiment of the present disclosure. 
         FIG. 12  is another cross-sectional end view of the positive displacement device illustrated in  FIG. 8 , where the positive displacement device is shown at one hundred and eighty degrees (180°) of shaft rotation in accordance with an example embodiment of the present disclosure. 
         FIG. 13  is another cross-sectional end view of the positive displacement device illustrated in  FIG. 8 , where the positive displacement device is shown at two hundred and twenty-five degrees (225°) of shaft rotation in accordance with an example embodiment of the present disclosure. 
         FIG. 14  is another cross-sectional end view of the positive displacement device illustrated in  FIG. 8 , where the positive displacement device is shown at two hundred and seventy degrees (270°) of shaft rotation in accordance with an example embodiment of the present disclosure. 
         FIG. 15  is another cross-sectional end view of the positive displacement device illustrated in  FIG. 8 , where the positive displacement device is shown at three hundred and fifteen degrees (315°) of shaft rotation in accordance with an example embodiment of the present disclosure. 
         FIG. 16  is a partial exploded end view illustrating a positive displacement device in accordance with example embodiments of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     A conventional vane compressor is comprised of a stationary or fixed cylinder with a slot for receiving a reciprocating vane, an orbiting cylinder, a reciprocating vane with a vane spring, bearings, and a crankshaft with an eccentrically mounted shaft. The vane is inserted into the vane slot on the outer fixed cylinder with one end maintaining contact with the smaller orbiting cylinder providing a barrier between high and low pressure within the cylinder cavity. 
     As described herein, a positive displacement device, which can be configured as a vane compressor, can include two orbiting cylinders, rigidly connected at one end by a plate, rather than one orbiting cylinder within a larger fixed cylinder. In embodiments of the disclosure, the inner cylinder is smaller than the fixed cylinder and the larger orbiting cylinder is larger than the fixed cylinder. In some embodiments, a common vane may pass through a vane slot in the fixed cylinder wall, maintaining sealing contact with both the inner and outer orbiting cylinder surfaces. In this configuration, the smaller orbiting cylinder controls the vane position from below while the larger orbiting cylinder controls the vane position from above. Thus, a vane spring, which is typically used to maintain contact between the vane tip radius and the orbiting cylinder, is not necessarily required. 
     While a conventional vane compressor provides one compression cavity divided into low and high pressure regions, the positive displacement devices described herein can provide two compression cavities, each divided into low and high pressure regions. The inner cavity is formed between the inner orbiting cylinder surface and the fixed cylinder surface, and has a smaller displaced volume than that of the outer cavity. The outer compression cavity is formed between the fixed cylinder surface and the outer orbiting cylinder surface, and has the larger displaced volume. Thus, a positive displacement device as described herein may be configured as either a single stage compressor or a two stage compressor, e.g., with a single fixed and orbiting cylinder set. For a two stage design, the larger outer cavity may be used for the first stage, and the smaller inner cavity may be used for the second stage. 
     It should be noted that the outer and inner compression cavities, while sharing a common vane and common orbiting and fixed cylinders, are two separate cavities with compression cycles sequenced one hundred and eighty degrees (180°) apart. This configuration can reduce peak compressor torque and/or associated noise and vibration while increasing motor running efficiency. Further, dual concentric sequential compression chambers can support the addition of flow control valves for switching between four levels of mass flow and single stage or two stage compression to increase efficiency (e.g., as weather conditions vary) while also enabling start relief (e.g., for the compressor motor). In embodiments of the disclosure, flow control valves can be located within a compressor enclosure and/or outside of the enclosure. When placed outside of a compressor enclosure, ease of maintenance and/or improved control wiring access may be provided. Additionally, an outside placement can provide for simplified control features and/or upgrade options with a common compressor design. Available features may range from a baseline unit without control valves, two or three additional mass flow levels plus single or two stage compression options, a start relief option, and so on. With outside flow control valves, these options may be available from a manufacturer and/or may added in the field. 
     Referring now to  FIGS. 1 through 16 , positive displacement devices  100  are described. A positive displacement device  100  can be used for various applications, including, but not necessarily limited to, pumping fluid and/or gas. For example, a positive displacement device  100  can be used as a compressor for refrigeration and/or air conditioning applications, and so forth. The apparatus, systems, and techniques described herein, can provide low cost, low noise, and/or high efficiency oil lubricated rotary compressors that can be used in, for example, refrigeration compressor applications. Using concentric sequential compression, a low clearance volume may be provided. Further, the positive displacement device  100  can facilitate start unloading. In some embodiments, a single wrap design allows for a reduced compressor diameter and/or leakage area (e.g., as compared to a multiple wrap design). Further, a positive displacement device  100  can provide higher liquid slugging tolerance (e.g., because the orbiting cylinders are not restricted from moving away from the stationary cylinder to relieve pressure spikes). 
     In embodiments of the disclosure, a positive displacement device  100  includes a first cylinder  102  having a wall  104  with an interior surface  106  and an exterior surface  108 . The positive displacement device  100  also includes a second cylinder  110  disposed within the first cylinder  102 . The second cylinder  110  has an exterior surface  112 . The interior surface  106  of the first cylinder  102  and the exterior surface  112  of the second cylinder  110  define an inner cavity  114 . The positive displacement device  100  also includes a partition between the interior surface  106  of the first cylinder  102  and the exterior surface  112  of the second cylinder  110  to divide the inner cavity  114  into a first inner region  116  and a second inner region  118 , where a first port (e.g., first intake port  120 ) is in fluid communication with the first inner region  116  of the inner cavity  114 , and a second port (e.g., first exhaust port  122  is in fluid communication with the second inner region  118  of the inner cavity  114 . 
     The positive displacement device  100  also includes a third cylinder  124  disposed around the first cylinder  102 . The third cylinder  124  has an interior surface  126 . The exterior surface  108  of the first cylinder  102  and the interior surface  126  of the third cylinder  124  define an outer cavity  128 . The positive displacement device  100  also includes another partition between the exterior surface  108  of the first cylinder  102  and the interior surface  126  of the third cylinder  124  to divide the outer cavity  128  into a first outer region  130  and a second outer region  132 , where a third port (e.g., second intake port  134 ) is in fluid communication with the first outer region  130  of the outer cavity  128 , and a fourth port (e.g., second exhaust port  136 ) is in fluid communication with the second outer region  132  of the outer cavity  128 . For the purposes of the present disclosure, the term “third cylinder” shall be defined as any three-dimensional shape having a cylindrical interior surface, and shall encompass the shapes described with reference to the accompanying figures, along with other shapes not described in the accompanying figures. For example, a third cylinder as described herein may be a rectangular prism having a cylindrical interior surface, a hexagonal prism having a cylindrical interior surface, and so on. 
     The positive displacement device  100  includes one sealing interface for sealing first ends of the inner cavity  114  and the outer cavity  128 , and another sealing interface for sealing second ends of the inner cavity  114  and the outer cavity  128 . For example, the first cylinder  102  is connected to one end plate  138 , and the second and third cylinders  110  and  124  are connected to another end plate  140 . In embodiments of the disclosure, the second cylinder  110  and the third cylinder  124  are configured to orbit with respect to the center of the first cylinder  102  to create alternating regions of high pressure and low pressure in the first and second inner regions  116  and  118  of the inner cavity  114  and the first and second outer regions  130  and  132  of the outer cavity  128 . 
     With reference to  FIGS. 1 through 4C , in some embodiments, a positive displacement device  100  can be constructed using a through-shaft design. For example, a crankshaft  142  may extend through the end plates  138  and  140 . A drive mechanism, such as a motor, can be used to drive the second and third cylinders  110  and  124  in orbit with respect to the first cylinder  102 . Referring to  FIG. 4 , the end plate  138  can include a journal bearing  144 , and the end plate  140  can include an eccentric journal bearing  146 . This configuration may facilitate reduced shaft bearing loads and/or shaft deflection (e.g., because a through-shaft design allows the piston load to be shared by two shaft bearings). Further, a reduction of non-symmetric axial thrust between fixed and orbiting pistons can be achieved (e.g., when the eccentric bearing is located in the plane of the piston). In other embodiments, the positive displacement device  100  does not necessarily use a through-shaft design. For example, with reference to  FIGS. 5 through 7 , the second cylinder  110  can be connected to a shaft  148  that passes through a bearing in the end plate  138 . 
     Referring now to  FIGS. 8 through 15 , the partition between the interior surface  106  of the first cylinder  102  and the exterior surface  112  of the second cylinder  110 , and the partition between the exterior surface  108  of the first cylinder  102  and the interior surface  126  of the third cylinder  124 , can each be formed by a single vane  152  slidably extending through a vane slot  154  radially formed in the wall  104  of the first cylinder  102  and moveable with respect to the second cylinder  110  and the third cylinder  124 . The vane  152  is in sealing contact with the wall  104  of the first cylinder  102 , the exterior surface  112  of the second cylinder  110 , and the interior surface  126  of the third cylinder  124 . The vane  152  has a first tip in sealing contact with the exterior surface  112  of the second cylinder  110  and a second tip in sealing contact with the interior surface  126  of the third cylinder  124 . The vane  152  provides a barrier between the high and low pressure regions. For example, in some embodiments, the second and third cylinders  110  and  124  can rotate randomly (e.g., allowing for even wear between the mating surfaces, heat distribution, etc.). In other embodiments, an anti-rotation device can be used to prevent or minimize rotation of the second and third cylinders  110  and  124  as the cylinders orbit the center of the first cylinder  102 . In some embodiments, a separate vane can be included to form each partition (e.g., each using a vane spring and/or another biasing mechanism to maintain contact with the interior and/or exterior surfaces of the cylinders). 
     In embodiments of the disclosure, the first and second intake ports  120  and  134  are provided for supplying a fluid or gas to the positive displacement device  100 , while the first and second exhaust ports  122  and  136  are provided for supplying the fluid or gas from the positive displacement device  100 . In some embodiments, the first cylinder  102 , the second cylinder  110 , and the third cylinder  124  can be placed within an outer shell, or an outer compressor housing  156 . As the second and third cylinders  110  and  124  orbit the center of the first cylinder  102 , pockets of space, or compression cavities, are created adjacent to the first and second intake ports  120  and  134 . Fluid or gas enters these compression cavities via the first and second intake ports  120  and  134 . As the second and third cylinders  110  and  124  continue to orbit the center of the first cylinder  102 , the compression cavities are separated from the first and second intake ports  120  and  134  and migrate toward the first and second exhaust ports  122  and  136 . When the compression cavities are adjacent to the first and second exhaust ports  122  and  136 , the fluid or gas is supplied from the positive displacement device  100 . For instance, compressed gas may be supplied to a storage tank, or the like. 
     It should be noted that while two second and third cylinders  110  and  124  are illustrated in the accompanying figures, more or fewer cylinders may be included with a positive displacement device  100 . For example, the third cylinder  124  may be replaced with a compression spring and/or another biasing mechanism for biasing the vane  152  against the first cylinder  102 . Further, additional cylinders and/or additional vanes may be included to create additional compression chambers. 
     In embodiments of the disclosure, surfaces on both the second and third cylinders  110  and  124 , and the first cylinder  102 , are circular in cross-section, or formed by constant radii. Because the vane  152  inserted between the second and third cylinders  110  and  124  is a separate part, the constant radius compression cavity surfaces on the second and third cylinders  110  and  124 , and the first cylinder  102 , can be machined using conventional turning processes, which may be performed with greater accuracy and/or at a comparatively lower cost (e.g., when compared to a non-constant radius configuration). 
     Referring now to  FIG. 16 , in some embodiments, a series of mathematical equations can be used to define the relationships between the geometry of the first cylinder  102 , the second and third cylinders  110  and  124 , and four defining radii. These relationships may provide a continuous seal in the compression cavities. For the following discussion, S is equal to the stroke, or the travel distance of the second and third cylinders  110  and/or  124  in a straight line (e.g., twice the crankshaft eccentricity). W is equal to the thickness of the wall  104  of the first cylinder  102 . R 1  is equal to the outside radius of the exterior surface  112  of the second cylinder  110 , or the radius of the compression surface of the second cylinder  110 . This radius may be selected based upon space requirements. For example, if the central region of the second cylinder  110  is enlarged to pass the crankshaft  142  through, the outside radius R 1  of the second cylinder  110  may be determined by space requirements for the compressor shaft, eccentric, and eccentric bearing, plus a minimum wall thickness for the second cylinder  110 . 
     R 2 , which is equal to the inside radius of the interior surface  126  of the third cylinder  124 , or the radius of the compression surface of the third cylinder  124 , can then be determined as follows:
 
 R 2= R 1+ S+W  
 
     R 3 , which is equal to the inside radius of the interior surface  106  of the first cylinder  102 , or the radius of the inside compression surface of the first cylinder  102 , can be determined as follows:
 
 R 3= R 1+ S/ 2
 
     R 4 , which is equal to the outside radius of the exterior surface  108  of the first cylinder  102 , or the radius of the outer compression surface of the first cylinder  102 , can be determined as follows:
 
 R 4= R 3+ W  
 
     In embodiments of the disclosure, VW, which is equal to the width of the vane  152 , can be selected to allow the vane  152  to travel radially through the first cylinder  102 , while providing minimum clearance for gas sealing purposes. The width of the vane  152  may be selected based upon space requirements, and the width of the vane slot  154  in the first cylinder  102  may be equal to the vane width VW plus a desired seal clearance. It should be noted that a comparatively small vane width VW may increase the bending stress on the vane  152  (e.g., due to gas pressure and/or friction between the vane  152  and the second and third cylinders  110  and  124 ). Further, a vane width VW that permits the second and third cylinders  110  and  124  to contact the edge of the vane  152  may cause a loss of vane seal and/or excessive wear between the vane  152  and the orbiting surfaces the second and third cylinders  110  and  124 . Thus, the width of the vane  152  can be selected to be greater than at least a minimum vane width. For instance, VW m , which is equal to this minimum vane width, can be determined as follows:
 
 VW   m   =S *( R 2− R 1)/( R 2+ R 1)
 
     VL, which is equal to the length of the vane  152 , or the distance between the two outer ends of the vane, can be determined as follows:
 
 VL=R 2− R 1
 
     In embodiments of the disclosure, the vane  152  includes a tip radius, or a radius at the two outer ends of the vane. VTR, which is equal to this vane tip radius, can be determined as follows:
 
 VTR=VL/ 2
 
     It should be noted that the positive displacement device  100  may include other dimensional relationships and that the dimensional relationships heretofore described are provided by way of example only and not meant to limit the present disclosure. Thus, the positive displacement device  100  of the present invention is not necessarily limited to these dimensional relationships. Additionally, for the purposes of the present disclosure, the term “equal to” shall be understood to mean equal to within the limits of precision machinability. 
     Because the surfaces on the second and third cylinders  110  and  124  are circular, rotational orientation of the second and third cylinders  110  and  124  is not necessarily required. Thus, the need for an external anti-rotation device may be eliminated, allowing the second and third cylinders  110  and  124  to freely rotate while orbiting the center of the first cylinder  102 . A cost savings may be achieved by eliminating the anti-rotation device. Additionally, wear on the surfaces of the second and third cylinders  110  and  124 , which may be caused by the vane  152 , the first cylinder  102 , and/or the housing  156 , can be uniformly distributed over the entire mating surfaces (e.g., rather than being concentrated in a small region). Additionally, free rotation of the second and third cylinders  110  and  124  can uniformly distribute the heat of gas compression over the entire mating surfaces (e.g., again, rather than being concentrated in a small region). The apparatus, systems, and techniques described herein can provide a reduced peak wear rate and/or uniformity of temperature over the second and third cylinders  110  and  124 , and reduction of temperatures in the high pressure region, resulting in less part distortion, lower gas temperatures, and so forth. 
     It should be noted that while the compression cavities created by the inner and outer second and third cylinders  110  and  124  may share a common vane  152 , they can act as separate compression chambers, sequenced one hundred and eighty degrees (180°) apart. The apparatus, systems, and techniques described herein can reduce peak torque for single stage compressors, and may provide a two stage compressor design using the second and third cylinders  110  and  124 . For a two stage design, the larger outer cavity can be used for the first stage, and the smaller inner cavity can be used for the second stage. For example, in some embodiments, the first intake port  120  can be connected to (e.g., in fluid communication with) the second exhaust port  136  to form a two stage compressor. In this manner, fluid may flow from the second intake port  134  into the outer cavity  128  and from the outer cavity  128  to the second exhaust port  136  (forming a first compressor stage), from the second exhaust port  136  to the first intake port  120 , and then from the first intake port  120  into the inner cavity  114  and from the inner cavity  114  to the first exhaust port  122  (forming a second compressor stage). 
     It is noted that a large contributor to vane wear in typical stationary vane compressors is the pressure differential across the vane. Since these are predominantly single stage compressors, the maximum pressure differential across the vane is the discharge pressure minus the suction pressure. In the two stage version of the positive displacement device  100  described herein, the intermediate pressure is between the suction pressure and the discharge pressures. The differential pressure across the first stage end of the vane is the intermediate pressure minus the suction pressure. The differential pressure across the second stage end of the vane is the discharge pressure minus the intermediate pressure. Both of these differential pressures and resulting vane forces may be significantly lower than those of a typical stationary vane compressor. Thus, the resulting vane wear of a positive displacement device  100  may be comparatively lower than that of a typical stationary vane compressor. 
     As described herein, the center region of a positive displacement device  100  can be enlarged, moving the discharge port and compression cavities radially outward, without increasing the dead space adjacent to the discharge port at the end of the compression cycle. This configuration may yield a high compression ratio design. Enlarging the central region can be done to allow room for an eccentric, an eccentric bearing, a shaft, and shaft bearings, with the shaft passing through the eccentric and supported by shaft bearings on each side of the eccentric. This can reduce the radial forces on the shaft bearings, allowing the use of smaller bearings and/or shafting. Additionally, the eccentric can be located axially within the plane of the second and third cylinders  110  and  124  and the first cylinder  102 , allowing radial pressure forces between the second and third cylinders  110  and  124  to pass through the plane of the eccentric bearing and reduce non-symmetric axial thrust between the second and third cylinders  110  and  124  and the first cylinder  102 . 
     A positive displacement device  100  may have one or both of the second and third cylinders  110  and  124 , and/or the first cylinder  102 , coated with an abradable coating of sufficient thickness to cause interference at all sealing surfaces between the members. During the manufacturing or assembly sequence, the second and third cylinders  110  and  124 , and the first cylinder  102 , can be assembled and operated, causing the excess coating to abrade away leaving a near perfect match between the surfaces of the second and third cylinders  110  and  124  and the first cylinder  102 . This process may reduce the need for precise machining. 
     Although the subject matter has been described in language specific to structural features and/or process operations, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.