Patent Publication Number: US-8985980-B2

Title: Compressor with rotating cam and sliding end vanes

Description:
TECHNICAL FIELD 
     The embodiments disclosed herein relate to apparatus for compressing or pumping fluids, and particular to such apparatus having one or more sliding end vanes for engaging a rotating cam. 
     BACKGROUND 
     Compressors and pumps are commonly used to transfer mechanical energy to fluids. Some of these compressors and pumps have rotary designs, which can provide efficient and continuous energy transfer. However, these rotary designs are often complicated and expensive to manufacture and maintain. 
     One example of a rotary compressor is described in U.S. Patent Application Publication No. 2003/0108438 (Kim et al.). The compressor includes a cylinder assembly having a compression space through which suction passages and discharge passages are connected. A slanted compression plate is installed in the compression space and divides the compression space into two parts. The slant plate is rotatably connected to a rotation driving unit. Vanes are located on both sides of the slant compression plate to separate each of the two partitioned compression spaces into a suction space and a compression space. As the compression plate rotates, the vanes slide along the compression plate so that the fluid enters the suction space while fluid in the compression space is compressed and discharged. 
     One problem with the compressor of Kim et al. is that it can be difficult to maintain seals around the suction space and compression space on each side of the compression plate. Furthermore, it can be difficult to perform maintenance on the vanes or the slanted compression plate in the event that either of them wears down or breaks. 
     In view of the above, there is a need of a new apparatus for compressing or pumping fluids. 
     SUMMARY 
     According to some embodiments, there is an apparatus for compressing or pumping fluid. The apparatus comprises a housing having an interior chamber. The housing includes a first end wall on one side of the interior chamber. The first end wall has a fluid inlet and a fluid outlet. A rotating cam is rotatably mounted within the interior chamber. The rotating cam comprises a cam body having a first end located adjacent to the first end wall. The first end has a first sloped annular channel formed therein. The first sloped annular channel includes a ramp that is circumscribed by inner and outer circumferential sidewalls. The apparatus also comprises a first end vane slidably mounted within a slot in the first end wall so as to extend into the first sloped annular channel for sliding therein as the rotating cam rotates. The first end vane is biased towards the ramp so as to divide the sloped annular channel into an inlet chamber and an outlet chamber such that, as the rotating cam rotates, the inlet chamber expands and communicates with the fluid inlet for receiving the fluid, and the outlet chamber contracts and communicates with the fluid outlet for expelling the fluid. 
     The apparatus may further comprise a vane housing removably attached to the first end wall. The vane housing has a vane slot for slidably receiving the end vane therein. The apparatus may further comprise a biasing element within the vane housing for biasing the end vane against the ramp. 
     The first end vane may have a tapered tip, and the inner and outer circumferential sidewalls may be tapered inwardly towards the ramp corresponding to the tapered tip of the end vane. 
     The cam body may have a second sloped annular channel formed therein, and the apparatus may further comprise a second end vane slidably mounted to the housing and extending into the second sloped annular channel for sliding within the second sloped annular channel as the rotating cam rotates. 
     The second sloped annular channel may be formed on a second end of the cam body that is opposite to the first end, and the second end vane may be slidably mounted to a second end wall of the housing that is located opposite to the first end wall. 
     The second sloped annular channel may be formed on the first end of the cam body concentrically with the first sloped annular channel, and the second end vane may be slidably mounted to the first end wall of the housing. 
     The cam body may be a cylindrical block. The ramp may extend inwardly into the cylindrical block along a helical path. The helical path may start and finish at a raised portion. 
     The housing may include a cylindrical shell and the first end wall may be removably attached to the cylindrical shell. 
     The end vane may be configured to seal against the ramp and the inner and outer circumferential sidewalls. 
     The ramp may have a raised portion for maintaining contact with the first end wall as the rotating cam rotates, and the raised portion may cooperate with the first end vane to divide the first sloped annular channel into the inlet chamber and the outlet chamber. 
     According to some embodiments, there is an apparatus for compressing or pumping fluid. The apparatus comprises a housing having an interior chamber. The housing includes two end walls located on opposing sides of the interior chamber. Each end wall has a fluid inlet and a fluid outlet. A rotating cam is rotatably mounted within the interior chamber. The rotating cam comprises a cam body having two ends. Each end is located adjacent to one of the end walls and has at least one sloped annular channel formed therein. Each sloped annular channel includes a ramp that is circumscribed by inner and outer circumferential sidewalls. The apparatus also includes at least two end vanes. Each end vane is slidably mounted within a slot in one of the end walls so as to extend into a respective one of the sloped annular channels for sliding therein as the rotating cam rotates. Each end vane is biased towards the ramp so as to divide the respective sloped annular channel into an inlet chamber and an outlet chamber such that, as the rotating cam rotates, the inlet chamber expands and communicates with the fluid inlet for receiving the fluid, and the outlet chamber contracts and communicates with the fluid outlet for expelling the fluid. 
     The apparatus may further comprise at least two vane housings. Each vane housing may be removably attached to one of the end walls. The vane housing may have a vane slot for slidably receiving one of the end vanes therein. 
     Each end vane may have a tapered tip, and the inner and outer circumferential sidewalls of each respective sloped annular channel may be tapered inwardly towards the ramp corresponding to the tapered tip of the end vane. 
     Each end of the cam body may at least two sloped annular channels arranged concentrically therein, and wherein there are at least two end vanes slidably mounted to each of the end walls for extending into a respective one of the at least two sloped annular channels. 
     The cam body may be formed as a cylindrical block. The ramp of each sloped annular channel may extend inwardly into the cylindrical block along a helical path. The ramp of each sloped annular channel may have a raised portion for maintaining contact with the respective end wall as the rotating cam rotates, and the raised portion may cooperate with each respective end vane to divide the sloped annular channel into the inlet chamber and the outlet chamber. 
     Other aspects and features will become apparent, to those ordinarily skilled in the art, upon review of the following description of some exemplary embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The drawings included herewith are for illustrating various examples of the present specification. In the drawings: 
         FIG. 1  is a perspective view of an apparatus for compressing or pumping fluids according to an embodiment of the present invention; 
         FIG. 2  is an exploded perspective view of the apparatus of  FIG. 1 ; 
         FIG. 3  is a perspective view of a rotating cam and an end vane of the apparatus of  FIG. 1 ; 
         FIG. 4  is a cross-sectional view of the apparatus of  FIG. 1  along the line  4 - 4 ; 
         FIGS. 5A ,  5 B,  5 C and  5 D are top plan views of the cam and end vane shown in  FIG. 3 , in which fluid is being progressively received and discharged from a sloped annular channel as the cam rotates; 
         FIG. 6  is an exploded perspective view of an apparatus for compressing or pumping fluids according to another embodiment of the present invention; 
         FIG. 7  is a cross-sectional view of the apparatus of  FIG. 6  along the line  7 - 7 ; 
         FIG. 8  is a front elevational view of a tapered end vane of the apparatus of  FIG. 6 ; 
         FIG. 9  is a perspective view of another rotatable cam having two concentric sloped annular channels and two end vanes therein according to another embodiment of the present invention; 
         FIG. 10  is a cross-sectional view of the rotatable cam and end vanes of  FIG. 9  along the line  10 - 10 ; and 
         FIG. 11  is a perspective view of another rotatable cam that includes a circumferential gear driven by a pinion gear according to another embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIGS. 1-4 , illustrated therein is an apparatus  10  for use in compressing or pumping fluids. The apparatus  10  includes a housing  20  having an interior chamber  22  enclosed by two end walls  24 . As shown in  FIG. 2 , a rotating cam  23  is rotatably mounted within the interior chamber  22 , and two end vanes  28  are slidably mounted within a slot  25  in the end walls  24 . The rotating cam  23  comprises a cam body  26  having two opposing ends  27  with cam surfaces thereon. Each end  27  is located adjacent to one of the end walls  24  of the housing  20 . Furthermore, each cam surface is defined by a sloped generally annular channel  30  formed on each end  27  of the cam body  26  (only one sloped annular channel  30  can be seen in  FIGS. 2 and 3 ). The end vanes  28  extend into the sloped annular channels  30  and divide each respective sloped annular channel  30  into an inlet chamber  30 A and an outlet chamber  30 B. In operation, when the rotating cam  23  rotates, the end vanes  28  slide within the sloped annular channels  30  so that the inlet chamber  30 A expands and receives a fluid, while the outlet chamber  30 B contracts and expels the fluid out from the apparatus  10 . 
     Referring now to  FIGS. 1 and 2 , the housing  20  includes the two end walls  24  and a generally cylindrical shell  34  located therebetween. Together, the end walls  24  and the shell  34  cooperate to define the interior chamber  22 . The interior chamber  22  is sized and shaped to receive the cam body  26 . As shown, the interior chamber  22  generally has a cylindrical shape. 
     Each end wall  24  may be removably attached to the cylindrical shell  34 , for example, using one or more removable fasteners  38  such as screws, bolts, locking clips, and the like. This allows access to the rotating cam  23  or end vanes  28 , which can be beneficial when performing maintenance or repairs. In other examples, one of the end walls  24  may be affixed to the shell  34 , or formed integrally therewith. 
     With reference to  FIG. 2 , each end wall  24  also includes a fluid inlet  42  and a fluid outlet  44 . The fluid inlets and outlets  42  and  44  are generally aligned with the sloped annular channels  30  on the cam body  26 . Thus, as the rotating cam  23  rotates, fluid can enter the sloped annular channels  30  through the inlet  42 , and can then be expelled through the outlet  44 . 
     The apparatus  10  may also include a manifold block  46  attached to each end wall  24 . Each manifold block  46  may be formed with the fluid inlet and outlet  42  and  44  therein. In other examples, the inlet and outlet  42  and  44  may be formed directly on the end walls  24 . 
     Each end wall  24  and manifold block  46  may also have a slot  25  for receiving the end vane  28  therethrough. The slot  25  is located between the inlet  42  and outlet  44 . 
     Referring now to  FIGS. 2-4 , the cam body  26  is rotatably mounted within the interior chamber  22  along a rotational axis A. The cam body  26  may be rotated about the rotational axis A by a drive mechanism. For example, the drive mechanism may include a drive shaft  48  extending through the end walls  24  and into a central bore  47  within the cam body  26 . The shaft  48  and the central bore  47  generally have corresponding cross-sectional shapes (such as the hexagonal shape shown), which allows the shaft  48  to rotatably drive the cam body  26 . As shown in  FIGS. 2 and 4 , a bushing  49  may be positioned between the shaft  48  and each end wall  24  to allow for free rotation of the shaft  48  relative to the end wall  24 . While not shown, the shaft  48  may be driven by a motor or another source of rotary power. In some examples, the drive mechanism could have other configurations, such as a motorized gear assembly that drives a gear attached to the outer circumferential surface of the cam body  26  (e.g. as shown in  FIG. 11 ). 
     With reference to  FIG. 3 , each sloped annular channel  30  formed in the cam body  26  includes a ramp  50  circumscribed by inner and outer circumferential sidewalls  52  and  54 . The ramp  50  and sidewalls  52  and  54  are generally sized and shaped to allow the end vane  28  to slide within the sloped annular channel  30  while maintaining a seal therebetween. This can help isolate the inlet chamber  30 A from the outlet chamber  30 B. 
     The ramp  50  has a raised portion  56  that maintains contact with the end wall  24  as the rotating cam  23  rotates. As shown, the raised portion  56  may have a generally trapezoidal shape with a flat top that maintains contact with the end wall  24 . In operation, the raised portion  56  cooperates with the end vane  28  to divide the sloped annular channel  30  into the inlet chamber  30 A and the outlet chamber  30 B. Specifically, the inlet chamber  30 A is defined between the raised portion  56  and a front-side  28 A of the end vane  28 , and the outlet chamber  30 B is defined between a back-side  28 B of the end vane  28  and the raised portion  56 . 
     In the illustrated embodiment, the cam body  26  is formed as a solid block of material having a generally cylindrical shape corresponding to the interior chamber  22 . Making the cam body  26  from a solid block of material enables the formation of the ramp  50  and sidewalls  52  and  54 . Specifically, the ramp  50  extends into the cylindrical block, and the sidewalls  52  and  54  extend axially outwardly from the ramp  50  to the outer ends of the cam body  26 . 
     As shown, the ramp  50  may extend into the cam body  26  along a generally helical path. This can provide gradual compression or pumping of the fluid within the outlet chamber  30 B. The helical path generally starts and finishes at the raised portion  56 . Moreover, the ramp  50  includes a sloped entry  58  that drops off at the beginning of the helical path. This sloped entry  58  can help guide the end vane  28  down to the bottom of the ramp  50  as the inlet chamber  30 A begins to expand. 
     As shown, there may be seals  59  between the cam body  26  and the end wall  24 . For example, the seals  59  may include O-rings positioned on the ends  27  of the cam body  26  at locations radially outwardly from the sloped annular channels  30 . This may help to seal fluid within the sloped annular channels  30 . While not shown, there may also be seals located radially inwardly of the sloped annular channels  30  (e.g. around the shaft  48 ). 
     Referring again to  FIGS. 2 and 3 , the end vanes  28  are configured to slide within the sloped annular channels  30 . In some examples, the end vanes  28  may be made from compressible materials such as soft plastics or rubberized materials. This can help provide a tight fit within the sloped annular channels  30  and can help seal and isolate the inlet chamber  30 A from the outlet chamber  30 B. 
     The end vanes  28  are also configured to reciprocate up and down along the rotational axis A as the end vanes  28  slide within the sloped annular channels  30 . In order to allow this reciprocating movement, each end vane  28  may be received within a vane housing  60  that is attached to the end walls  24 . Each vane housing  60  has a vane slot  62  for slidably receiving the end vane  28  therein. The vane slot  62  is generally aligned with the slot  25  in the end wall  24  and the manifold block  46 . Furthermore, the combined length of the slot  25  and vane slot  62  is longer than the end vane  28 . This extra length allows the end vane  28  to reciprocate along the rotational axis A as the end vane  28  slides within the sloped annular channel  30 . 
     In some embodiments, the vane housing  60  may be removably attached to the end walls  24 . For example, each vane housing  60  may be attached to a respective end wall  24  using one or more removable fasteners such as screws, bolts, locking clips, and the like. This can allow quick and easy replacement of the end vane  28  by detaching the vane housing  60  from the end wall  24 , which can be particularly useful if the end vanes  28  wear down over time. 
     The end vanes  28  are generally biased toward the ramp  50 . For example, the apparatus  10  may include a biasing element for biasing the end vane  28  into its respective sloped annular channel  30 . For example, the vane housing  60  may include a port  64  for receiving a pressurized fluid that biases the end vane  28  against the ramp  50 . The pressurized fluid may be supplied from a fluid pressure control system (not shown). In other examples, the biasing element may include another type of biasing element such as one or more springs (as with the embodiment shown in  FIG. 7 ). 
     Referring now to  FIGS. 5A-5D , operation of the apparatus  10  will now be described. In  FIG. 5A , the raised portion  56  of the ramp  50  is rotationally aligned with the end vane  28 . This may be referred to as a starting position. At this point, the sloped annular channel  30  may be empty, or filled with a fluid. 
     As will be described below, the apparatus  10  generally operates in two cycles, namely, an intake cycle and a discharge cycle. With reference to  FIG. 5B , the intake cycle begins with the rotating cam  23  rotating clockwise. While rotating, the tip of the end vane  28  is biased downward and slides down the sloped entry  58 . At this point, the inlet chamber  30 A begins to form between the front-side  28 A of the end vane  28  and the raised portion  56 , and fluid enters the inlet chamber  30 A through the inlet  42 . As the rotating cam  23  continues to rotate ( FIGS. 5C-5D ), the inlet chamber  30 A continues to expand and more fluid is drawn in. The inlet chamber  30 A becomes filled with fluid after rotating the rotating cam  23  through one complete revolution. 
     The discharge cycle begins on the next revolution of the rotating cam  23 . Specifically, the fluid received within the inlet chamber  30 A during the previous revolution is subsequently compressed or pumped during the next revolution. More specifically, as shown in  FIGS. 5A and 5B , after the raised portion  56  passes by the end vane  28 , the outlet chamber  30 B extending between the raised portion and the back-side  28 B is generally filled with fluid from the previous rotation (i.e. the inlet chamber  30 A from the previous revolution becomes the outlet chamber  30 B for the next revolution). As shown in  FIGS. 5B-5D , further rotation of the rotating cam  23  causes the space between the raised portion  56  and the back-side  28 B of the end vane  28  to decrease. This contraction of the outlet chamber  30 B can be used to pump fluid (e.g. by keeping the fluid outlet  44  open), or to compress fluid (e.g. by restricting flow through the fluid outlet  44 ). For example, as shown in  FIGS. 5B-5C , the fluid outlet  44  may be kept closed so that the fluid within the outlet chamber  30 B gradually compresses as the rotating cam  23  continues rotating. When the rotating cam  23  reaches a particular point (e.g. the point shown in  FIG. 5D ), the fluid outlet  44  may be opened and the compressed fluid may be pumped out through the fluid outlet  44 . The opening and closing of the outlet  44  may be controlled using a valve (not shown). 
     During regular operation, the intake cycle and discharge cycle occur generally contemporaneously or simultaneously with each other such that fluid is being discharged from the outlet chamber  30 B while fluid is also being received in the inlet chamber  30 A. This allows generally continuous operation of the apparatus  10 . 
     Referring now to  FIGS. 6-8 , illustrated therein is another apparatus  110  for use in compressing or pumping fluids. The apparatus  110  is similar in some respects to the apparatus  10  and where appropriate similar elements are given similar reference numerals incremented by one hundred. For example, the apparatus  110  includes a housing  120  having an interior chamber  122  enclosed by a removable end wall  124 , a rotating cam  123  rotatably mounted within the interior chamber  122  and comprising a cam body  126  having an end with a sloped generally annular channel  130  formed therein, and an end vane  128  slidably mounted within a slot in the end wall  124  for sliding within the sloped annular channel  130 . 
     One difference is that the housing  120  has a solid bottom  125  integrally formed with the cylindrical shell  134 . Accordingly, there is only one removable end wall  124 , with one end vane  128  mounted thereto. 
     With reference to  FIGS. 7-8 , another difference is that the end vane  128  is tapered towards a vane tip  170 , and the sloped annular channel  130  is formed with inner and outer circumferential sidewalls  152  and  154  that are tapered inwardly towards the ramp  150  at the same angle as the end vane  128 . Tapering the end vane  128  and the sidewalls  152  and  154  can help maintain a tight seal therebetween. Specifically, if the sides and tip  170  of the end vane  128  wear down over time, the sides of the end vane  128  tend to remain in contact with the circumferential sidewalls  152  and  154  by virtue of the tapering. In contrast, with a straight-edged end vane, the sides of the end vane may wear down and a gap may develop between the sides of the end vane and the sidewalls. 
     In some examples, the end vane  128  may be tapered at an angle  162  of less than about 90-degrees. More particularly, the taper angle  162  may be less than about 20-degrees, or more particularly still, less than about 10-degrees. In some examples, the taper angle  162  may be larger or smaller. 
     As shown in  FIG. 7 , the end vane  128  is also biased toward the sloped annular channel  130  using one or more springs  180 . The springs  180  are mounted within a vane housing  160 . In some examples, the springs  180  may be omitted and the end vane  128  may be biased toward the sloped annular channel  130  in other ways, for example, using gravity. 
     Referring now to  FIGS. 9 , illustrated therein is a rotating cam  223  and two end vanes  228  and  229  that are made in accordance with another embodiment of the invention. As shown, the rotating cam  223  comprises a cam body  226  having an end with sloped generally annular channels  230  and  232  formed concentrically therein. Each end vane  228  and  229  extends into one of the sloped annular channels  230  and  232  and is configured to slide therein as the rotating cam  223  rotates. 
     Each concentric sloped annular channel  230  and  232  includes its own ramp  250 A and  250 B, respectively. Furthermore, the ramp  250 A of the outer sloped annular channel  230  is circumscribed by a first set of inner and outer circumferential sidewalls  252 A and  254 A, and the ramp  250 B of the inner sloped annular channel  232  is circumscribed by a second set of inner and outer circumferential sidewalls  252 B and  254 B. The circumferential sidewalls  252 A,  254 A,  252 B and  254 B separate the sloped annular channels  230  and  232  from each other. As shown in  FIG. 10 , the other end of the cam body  226  also has two concentric sloped annular channels for receiving a corresponding set of end vanes (not shown). 
     Having two sloped annular channels on one or both ends of the cam body  226  allows multistage compression. For example, a fluid may be initially compressed within the outer annular channel  230 , and then further compressed within the inner annular channel  232 . In this case, a manifold block may be used to connect the outlet of the outer annular channel  230  to the inlet of the inner annular channel  232 . 
     While the illustrated embodiment has two concentric sloped annular channels  230  and  232  on each end of the cam body  226 , in other examples, there may be two or more concentric sloped annular channels on one or both ends of the cam body  226 . As shown, the circumferential sidewalls of each sloped annular channel may be tapered and the end vanes may also have corresponding tapered profiles. Alternatively, the sidewalls and end vanes may be straight. 
     The rotating cam  223  and end vanes  228  and  229  may be used with a housing generally similar to one of the housings  20  and  120  described above, albeit with some modification to accommodate the second end vane  229  within the inner sloped annular channel  232 . For example, there may be additional manifold blocks and vane housings removably attached to the end wall corresponding to each sloped annular channel and end vane therein. There may also be additional seals for separating or isolating one sloped annular channel from another. 
     Referring now to  FIG. 11 , illustrated therein is a rotating cam  323  made in accordance with another embodiment of the invention. As shown, the rotating cam  323  comprises a cam body  326  having an end with a sloped generally annular channel  330  formed therein. 
     As shown, the cam  323  also includes a circumferential gear  380  located on an outer circumferential surface of the cam body  326 . As shown, a shaft  348  with a pinion gear  382  may be used to rotatably drive the cam gear. The rotating cam  323  may be used with a housing and end vanes generally similar to the embodiments described above, albeit with some modification to accommodate the gear  380  and pinion gear  382 . 
     While the above description provides examples of one or more apparatus, methods, or systems, it will be appreciated that other apparatus, methods, or systems may be within the scope of the present description as interpreted by one of skill in the art.