Abstract:
A rotary vane device comprising a rotor and a vane positioned in a pumping chamber in a housing for rotation about respective eccentric axes, wherein the rotor has a rotor slot in which the vane is positioned, characterized by the vane being driven and the rotor following the vane.

Description:
RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 60/736,959 filed Nov. 15, 2005, which is hereby incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to rotary vane machines and, more particularly, to a rotary vane machine wherein the vane is driven rather than the rotor. 
       BACKGROUND OF THE INVENTION 
       [0003]    Rotary vane machines are distinguished from virtually all other fluid displacement machines in their remarkable simplicity. The operating efficiency of such machines, however, is negatively impacted by machine friction. Friction in non-guided rotary vane machines can arise from the rubbing of the tip of the sliding vane against the inner contour of the stator wall. Governing the motion of the vane by the stator wall contour also can inhibit the area through which fluid can enter or exit the machine. This can result in increased fluid flow pressure losses in the inlet and outlet port regions. 
         [0004]    Over the years, proposals have been made to move the vanes radially other than through the direct action of the vane tips rubbing along the inside casing or stator wall. Prior attempts have focused upon the use of wheels or rollers pinned to the sides of the vanes wherein these rollers follow a circular or non-circular track of an appropriate configuration. The cooperation of the rollers in the roller guide track controls the radial location of the vane which is pinned to the roller follower and hence determines the position of the tip of the vane. 
         [0005]    Another known and advantageous fluid-handling device employs a single vane. In essence, this single vane device operates in a manner similar to most conventional vane compressors, with two key exceptions: the rotor incorporates only a single slot for the simple vane, and that vane does not contact the housing while the rotor is spinning. Instead, an extremely thin air gap exists between the vane tip and the stator wall. In operation, air enters through a port on one side of the unit and is compressed by the front side of the vane. The vane&#39;s rear side, meanwhile, draws gas into the housing. 
       SUMMARY OF THE INVENTION 
       [0006]    In contrast to the above-mentioned single vane and other rotary vane devices, the present invention provides a rotary vane device wherein the vane is rotatably driven rather than the rotor. This has been found to beneficially reduce the side load acting on the vane, essentially to whatever is the bearing drag acting on the rotor that is rotatably driven by the vane. Benefits arising from the invention include less power consumption, longer life, fewer stack-up tolerances between the vane and housing, the ability to use plastic for the rotor and vane due to the reduced loads, and/or fewer components. 
         [0007]    Accordingly, the invention provides a rotary vane device comprising a rotor and a vane positioned in a pumping chamber in a housing, wherein the rotor has a rotor slot in which the vane is positioned, characterized by the vane being driven and the rotor following the vane. 
         [0008]    More particularly, the rotary vane device comprises a housing including a pumping chamber having an axis and flow passages for flow of fluid to and from the pumping chamber. A rotor is eccentrically positioned in the pumping chamber and supported in the housing for rotation about an axis eccentric to the pumping chamber axis whereby a variable volume space is formed between a radially outer surface of the rotor and a radially inner surface of the housing. The rotor has a radially extending slot opening to the radially outer surface of the rotor, and a vane drive member is supported in the housing for rotation about the pumping chamber axis. A vane is disposed in the rotor slot and coupled to the vane drive shaft independently of the rotor for rotation with the vane drive member about the pumping chamber axis. The vane has a radially outer end adjacent the radially inner surface of the housing and a side wall for engaging an opposed side wall of the rotor slot while permitting relative radial movement between the vane and the rotor slot, whereby rotation of the vane about the chamber axis will rotatably drive the rotor about the rotor axis within the chamber while the vane moves radially relative to rotor. 
         [0009]    The vane drive member may include a drive shaft coaxial with the pumping chamber axis, and the vane may be fixedly joined to the shaft for radial extension away from the shaft. 
         [0010]    The rotor slot may increase in width going from a radially outer end of the slot to a radially inner end of the slot, for accommodating relative pivotal movement of the vane relative to the side wall of the slot when the vane is rotatably driven about the pumping chamber axis. 
         [0011]    The vane may be attached to the drive shaft by a pair of axially spaced apart vane supports fixed to the drive shaft for rotation with the drive shaft, and the vane may extend axially between the vane supports. The housing may have axially spaced apart side walls defining respective axial ends of the pumping chamber, and the drive shaft may have opposite axial ends supported by bearings in the side walls, respectively. The vane may be radially outwardly spaced from the drive shaft for mass reduction purposes. 
         [0012]    The housing may include a stator plate having a through bore forming the pumping chamber, and opposite end plates may close the ends of the pumping chamber. 
         [0013]    The radially inner surface of the housing preferably is curved concentrically around the pumping chamber axis, and the radially outer surface of the rotor preferably is curved concentrically around the rotor axis. 
         [0014]    A seal member may be provided at the radially outer end of the vane for sealingly engaging the radially inner surface of the housing. 
         [0015]    The rotor may have opposite ends thereof supported by respective bearings in the housing. Each bearing may include an inner race, an outer race and anti-friction elements between the inner and outer races. 
         [0016]    The vane and rotor may be about equal in longitudinal length, and they may be rotationally (dynamically) balanced. 
         [0017]    The radially outer end of the vane may be convexly curved concentrically with the pumping chamber axis. 
         [0018]    Further features of the invention will become apparent from the following detailed description when considered in conjunction with the drawings. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0019]    In the annexed drawings: 
           [0020]      FIG. 1  is a perspective view of a rotary vane device in accordance with the invention; 
           [0021]      FIG. 2  is a perspective view of the rotary vane device of  FIG. 1 , but with an end plate removed to show interior components of the device including bearing elements; 
           [0022]      FIG. 3  is a perspective view similar to  FIG. 2 , but with bearing elements removed; 
           [0023]      FIG. 4  is a perspective view similar to  FIG. 3 , but with a rotor end member removed from the rotor body to show an end of a vane and drive member assembly; 
           [0024]      FIG. 5  is an end elevational view of the rotary vane device of  FIG. 1 , with the end plate removed to show interior components of the device including bearing elements; 
           [0025]      FIG. 6  is a perspective view of the vane and drive member assembly; and 
           [0026]      FIGS. 7-10  are views similar to  FIG. 4 , but shown in end elevation with the vane and drive member assembly shown at relatively rotated positions. 
       
    
    
     DETAILED DESCRIPTION 
       [0027]    Referring now to the drawings in detail, and initially to  FIGS. 1-5 , an exemplary rotary vane device according to the invention is designated generally by reference numeral  20 . As shown, the device  20  generally comprises a housing  21 , a rotor  22  ( FIGS. 3 and 4 ) and a vane and drive assembly  23  ( FIGS. 4 and 6 ). In the illustrated embodiment, the vane and drive assembly  23 , as best seen in  FIG. 6 , comprises a single vane  26  mounted, or formed integrally with, a vane drive member  27 . Although these components will be described below in greater detail, it will be appreciated that such components can vary in various respects without deviating from the basic principles of the present invention. In addition, the illustrated rotary vane device is particularly suited for use as a gas compressor and will be chiefly described in this context. A rotary vane device according to the invention, however, may be adapted for use with other fluids, in particular as a pump for liquids. Additionally, as is typical of many conventional compressors and pumps, the rotary vane device  20  can be reversely operated as a motor, where pressurized fluid is supplied to the device to effect rotation of the vane  26  to output a rotary motion. Those skilled in the art will readily appreciate the reversibility of the operation of the rotary vane device. 
         [0028]    Turning now to details of the various components, the housing  21  includes a pumping chamber  30  having an axis  31  and ports formed by inlet/outlet port members  34  and  35  for flow of fluid to and from the pumping chamber. The ports can be positioned in a conventional manner for supplying fluid to the pumping chamber and discharging pressurized fluid from the pumping chamber when operating as a compressor or pump, or conversely when operating as a motor. 
         [0029]    Preferably the housing  21  is assembled from several components. As shown, the housing  21 , which may be supported by a bracket  37 , includes a stator plate (block)  38  having a through bore forming the pumping chamber  30 , and opposite end (cover) plates  40  and  41  that close the ends of the through bore. The through bore is bounded by a radially inner surface  42  of the housing that preferably is curved concentrically around the pumping chamber axis, as is typical of known rotary vane type devices. The stator and end plates may be assembled together and secured to one another by suitable fasteners, such as the illustrated screws  43 . In the illustrated embodiment, the cylindrical wall of the stator plate  38  is provided with two openings that are covered by the port members  34  and  35 . 
         [0030]    The rotor  22  is eccentrically positioned in the pumping chamber  30  and supported in the housing  21  by bearings for rotation about an axis  49  eccentric to the pumping chamber axis  31  whereby a variable volume space is formed between a radially outer surface  50  of the rotor and the radially inner surface  42  of the housing. Preferably, the radially outer surface of the rotor is curved concentrically around the rotor axis. That is, the rotor is in the form of a right cylindrical body. 
         [0031]    As above noted, the rotor  22  is supported by bearings in the housing  21 . One such bearing is indicated at  53  in  FIGS. 2 and 5 , the bearing  53  having been removed in  FIGS. 3 and 4 . Although any suitable bearing may be employed, the bearing  53  includes an inner race  54  and an outer race  55  with a plurality of anti-friction elements, such as ball bearings, interposed therebetween. The inner race  54  is fitted on a tubular stub shaft  56  ( FIG. 3 ) projecting from the rotor  22 . In the illustrated embodiment, the stub shaft is provided on a rotor end member  57  fastened to an axial end of a rotor body  58  by suitable means, such as the fasteners  59 . The outer race is received in a correspondingly sized pocket formed in the end plate  40  of the housing. A similar arrangement is provided at the other end of the rotor. The bearings  53  provide for essentially friction-free rotation of the rotor in the pumping chamber about the rotor axis  49 . 
         [0032]    The rotor  22 , at its top as shown in  FIG. 5 , is in near contact with the inner surface  42  of the stator plate  38 . This provides a non-contact seal between the rotor and the inner surface of the stator plate at a location between the inlet/outlet ports  34  and  35 , thereby isolating one from the other although some leakage may occur. Consequently, the radius of the rotor plus the offset is only slightly less than the radius of the pumping chamber  30  so that no contact will occur while still minimizing any leakage between the rotor and the inner surface of the bore. On the other hand, the radius of the rotor should not be greater than the radius of the pumping chamber less offset between the pumping chamber axis and the rotor axis. Otherwise the outer surface of the rotor would engage the inner housing surface and preclude rotation of the rotor. 
         [0033]    The rotor  22  also is provided with a radially extending vane slot  68  opening to the radially outer surface of the rotor as best seen in  FIG. 4 . In the illustrated embodiment, the slot  16  extends the entire longitudinal length of the rotor body  58  which in turn is equal in width of the pumping chamber  30 , except for provision of necessary clearances to allow rotation of the rotor in the pumping chamber. Because the slot reduces the mass of the rotor on the side containing the slot, the other side may have material removed to dynamically balance the rotor, as desired. 
         [0034]    The slot  68  in the rotor  22  is configured to receive the vane  26 , which may have generally parallel side walls and a longitudinal length essentially the same as the longitudinal length of the rotor body  58 . In the illustrated embodiment, the vane is integrally formed as part of the vane and drive assembly  23 . The vane and drive assembly, as best seen in  FIG. 6 , further comprises a drive shaft (axle)  69  that is supported at each end by a respective bearing  71  in the housing for rotation about the pumping chamber axis  31 . Although any suitable bearing may be employed, the bearing  71  includes an inner race and an outer race with a plurality of anti-friction elements, such as ball bearings, interposed therebetween. The inner race is fitted on a reduced diameter end portion  72  of the shaft. The outer race is received in a correspondingly sized pocket formed in the end plate  40  of the housing  21 . The bearing  71  is axially outwardly spaced in relation to the bearing  53  that rotatably supports the rotor stub shaft  56 . The bearing  71  and  53  will also be radially offset from one another to provide the offset between the rotor axis  49  and the pumping chamber axis  31 . A similar arrangement is provided at the other end of the vane shaft  69 . 
         [0035]    The vane  26  preferably is fixedly joined to the drive shaft  69  for radial extension away from the shaft. As shown in  FIG. 6 , the vane may be attached to the drive shaft by a pair of axially spaced apart vane supports  75  and  76  fixed to the drive shaft for rotation with the drive shaft, and the vane may extend axially between the vane supports. The vane may be radially outwardly spaced from the drive shaft, particularly for mass reduction purposes. The vane preferably is dynamically balanced and to this end a counterweight  77  may be assembled between the vane supports diametrically opposite the vane. 
         [0036]    The vane  26  preferably has a radial length such that its radially outer end is in near contact with the inner surface  42  of the stator plate  38 . That is, the outer end (or tip) of the vane is spaced from the inner surface  42 . This provides a non-contact seal between the vane and the inner surface  42 . Opposite sides of the vane when projecting from the rotor form respective ends of variable volume spaces between the rotor and inner surface of the stator plate, although some leakage may occur through the small gap between the vane end and inner surface of the stator plate. The radially outer end of the vane may be convexly curved concentrically with the pumping chamber axis  31 . A clearance between the vane tip and the inner surface  42  surrounding the stator bore, in the range of 0.002 inches to 0.004 inches, has been found to provide desirable operating results while still permitting relatively low cost for manufacture of the unit. The same clearance can be provided between the top of the rotor  22  and the inner surface  42 . 
         [0037]    At its radially outer end, side walls of the vane  26  are positioned adjacent and for sliding engagement with respective side walls of the rotor slot  68  such that upon rotation of the vane, the leading side wall of the vane will push against the opposed side wall of the rotor slot while permitting relative radial movement between the vane and the rotor slot. In this manner, rotation of the vane about the chamber axis will rotatably drive the rotor  22  about the rotor axis  49  within the pumping chamber  30  while the vane moves radially relative to rotor. In the illustrated embodiment, surfaces of the vane and rotor function as bearing surfaces that provide the sliding engagement between the vane and slot in the rotor. As will be appreciated, such sliding engagement can be effected by other means such as the use of bearing devices, for example roller bearings. 
         [0038]    Any suitable means may be provided for transfer of rotary motion from outside the housing to the vane  26  for use of the rotary vane device as a compressor/pump, or for taking out rotary motion from the vane for use of the device as a motor. In the illustrated exemplary embodiment, one end of the drive shaft  69  is extended to project axially from the housing for coupling to an external device, such as a prime mover (e.g. electric motor, engine, etc.) or to a component to be driven by the device if used as a motor. 
         [0039]    It can now be appreciated that the vane  26  is coupled to a vane drive, in particular the vane drive shaft  69 , independently of the rotor  22  for rotation with the vane drive member about the pumping chamber axis. That is, vane is driven and the rotor follows the vane. This is in contrast to the conventional arrangement where the rotor is driven instead of the vane. 
         [0040]    In the case where the vane  26  is fixed to the drive shaft  69  against any relative movement, the vane, during rotation about the pumping chamber axis, will pivot relative to the rotor slot  68  while still drivingly engaging the rotor. To accommodate this relative pivotal movement, the rotor slot  68  in the rotor increases in width going from the radially outer end of the slot to a radially inner end of the slot. 
         [0041]    If desired, a seal member may be provided at the radially outer end of the vane  26  for sealingly engaging the radially inner surface  42  of the housing. The seal member may be a vane seal held and guided in a slot in the end of the vane such that the vane seal can move radially relative to the vane. The seal may be biased against the inner surface surrounding the pumping chamber or reliance can be had on centrifugal force to cause the seal to be urged radially outwardly against the inner surface when the vane is rotated. 
         [0042]    As will now be appreciated by those skilled in the art, the driving of the vane  26  rather than the rotor  22  will beneficially reduce the side load acting on the vane, essentially to whatever is the bearing drag acting on the rotor that is rotatably driven by the vane. This leads to less power consumption, longer life, fewer stack-up tolerances between the vane and housing, the ability to use plastic for the rotor and vane due to the reduced loads, and/or fewer components. As noted, the rotor and vane can be made of plastic, such as a suitable nylon of PFE material. For other applications, a carbon rotor and ceramic ball bearings can be used to stand up to corrosion associated with the hydrogen on board in fuel cells when the device is used as a compressor for hydrogen recirculation. Another version may employ steel ball bearings, as when the device serves as a cathode air compressor, for example in a fuel cell stack. In addition, many of the components can be formed from extrusions. 
         [0043]    In operation, rotation of the vane  26  in a clockwise direction in  FIGS. 6-9  will cause fluid, such as a gas, to be drawn in from the port  35  then functioning as an inlet port. This gas will flow into the expanding volume space behind vane as the vane moves clockwise from its position shown in  FIG. 6 . At the same time, the gas volume in front of the rotating vane will be decreasing in size as the rotor vane assembly continues to rotate to its positions shown in  FIGS. 7  and  8 . When the pressure within the compressing volume ahead of the vane exceeds the pressure into which the compressed gas is to be discharged, the gas will flow out through the other port  34 . 
         [0044]    Although the invention has been shown and described with respect to a certain preferred embodiment or embodiments, it is obvious that equivalent alterations and modifications will occur to others skilled in the art upon the reading and understanding of this specification and the annexed drawings. In particular regard to the various functions performed by the above described elements (components, assemblies, devices, compositions, etc.), the terms (including a reference to a “means”) used to describe such elements are intended to correspond, unless otherwise indicated, to any element which performs the specified function of the described element (i.e., that is functionally equivalent), even though not structurally equivalent to the disclosed structure which performs the function in the herein illustrated exemplary embodiment or embodiments of the invention. In addition, while a particular feature of the invention may have been described above with respect to only one or more of several illustrated embodiments, such feature may be combined with one or more other features of the other embodiments, as may be desired and advantageous for any given or particular application.