Abstract:
The present invention is a variable displacement pump having an inner rotor rotatable about a first axis and having at least two slots. The pump also has at least two vanes, each located in a distinct one of the at least two slots. The pump also has an outer rotor rotatable about a second axis, operably associated with the inner rotor, the outer rotor having two or more recesses, each configured to receive one of the vanes. The pump also includes an expandable chamber formed by the outer rotor and the inner rotor, an eccentric ring surrounding the outer rotor, and a housing. The eccentric ring is located within the housing for adjusting the relative relationship between the first axis and the second axis in order to vary the displacement of the pump.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a PCT International Application of U.S. Patent Application No. 60/922,683 filed on Apr. 10, 2007. The disclosure of the above application is incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to sliding vane pumps; more particularly, the present invention relates to sliding vane pumps having a stacked integrated vane configuration. 
       BACKGROUND OF THE INVENTION 
       [0003]    Sliding vane pumps are commonly used to transfer fluid from an inlet port to an outlet port. Typically, they have a ring which is eccentric, and an inner rotor; the inner rotor is typically fixed to and rotates with a shaft, and a series of vanes slide in and out of a set of vane slots. As the vanes rotate with the inner rotor, the vanes will slide along the inner surface of the eccentric ring. The eccentricity between the inner rotor and the eccentric ring can be varied to vary the amount of fluid that is displaced by the pump. 
         [0004]    Current designs for sliding vane pumps have several disadvantages, the most common of which relates to the wear that occurs between the vanes and the eccentric ring as the vanes slide in the ring. The wear is caused by drag between the vane tips and inner surface of the ring. This can cause a significant amount of torque loss. Another problem can be contamination within the pump which can affect reliability. 
         [0005]    Accordingly, there exists a need for an improved sliding vane pump which has improved efficiency, improved packaging, and has a reduction of wear between the vanes and the outer rotor. 
       SUMMARY OF THE INVENTION 
       [0006]    The present invention includes a variable displacement pump having an inner rotor rotatable about a first axis having at least two slots, with the slots substantially extending diametrically through the width of the inner rotor. The present invention also includes at least two vanes, each located in a distinct one of said at least two slots. The pump also has an outer rotor rotatable about a second axis and operably associated with the inner rotor. The outer rotor has two or more recesses, each configured to receive one of said at least two vanes. The pump also includes an expandable chamber formed by the outer rotor and the inner rotor, and an eccentric ring surrounding the outer rotor. Also included is a housing having an eccentric ring located within the housing for adjusting the relative relationship between the first axis and the second axis in order to vary the displacement of the pump. 
         [0007]    Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]    The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein: 
           [0009]      FIG. 1  is a sectional side view of a sliding vane pump with the outer rotor aligned with the inner rotor, according to the present invention; 
           [0010]      FIG. 2  is a sectional side view of a sliding vane pump with the outer rotor offset from the inner rotor; 
           [0011]      FIG. 3  is an exploded view of a sliding vane pump, according to the present invention; 
           [0012]      FIG. 4  a perspective view of a vane used in a sliding vane pump, according to the present invention; 
           [0013]      FIG. 5  is a side view of a vane used in a sliding vane pump, according to the present invention; 
           [0014]      FIG. 6  is a perspective view of a hub and inner rotor used in a sliding vane pump according to the present invention; 
           [0015]      FIG. 7  is a perspective view of an alternate embodiment of a sliding vane pump with the cover and housing removed, according to the present invention; 
           [0016]      FIG. 8  is a perspective view of a rotor used in an alternate embodiment of a sliding vane pump, according to the present invention; 
           [0017]      FIG. 9  is an first exploded view of an alternate embodiment of a sliding vane pump, according to the present invention; and 
           [0018]      FIG. 10  is a second exploded view of an alternate embodiment of a sliding vane pump, according to the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0019]    The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. 
         [0020]    Referring to the Figures generally, a sliding vane pump according to the present invention is generally shown at  10 . The pump  10  has an inner rotor  12  which rotates about a first axis  14 . The inner rotor  12  also has a series of slots  16  for receiving a plurality of vanes  18 . The vanes  18  have a first side  20  which is offset and parallel to a second side  22 . The vanes  18  also have a third side  21  which is parallel to and equal in length compared to a fourth side  23 . Both the third side  21  and fourth side  23  serve as a flat engagement  24 . The vane  18  also includes an extension  26  which is of a reduced width compared to the remainder of the vane  18 . The pump  10  also has an outer rotor  28  which rotates about a second axis  30 , and has recesses  32  for receiving the flat engagements  24  of the vanes  18 . 
         [0021]    The first side  20  being offset from the second side  22  creates an angle  27  between the flat engagements  24  and the first side  20 , as well as between the flat engagements  24  and the second side  22 . The recesses  32  are in sliding contact with each of the flat engagements  24 . An individual example of one of the vanes  18  is depicted in  FIGS. 4 and 5 . 
         [0022]    Surrounding the outer rotor  28  is an eccentric ring  34  located within a housing  36 . Located in between the inner rotor  12  and the outer rotor  28  is an expandable chamber  38  used for pumping fluid. The housing  36  also includes an inlet port  40  for delivering fluid into the expandable chamber  38 , and an outlet port  42  for receiving fluid from the expandable chamber  38 . There is also an inlet aperture  43  in fluid communication with the inlet port  40 , where fluid is fed into the inlet port  40  via the inlet aperture  43  prior to being pumped by the pump  10 . There is also an outlet aperture  45  in fluid communication with the outlet port  42 ; once the fluid is pumped by the pump  10 , the fluid passes from the outlet port  42  through the outlet aperture  45  to a device requiring pressurized fluid. 
         [0023]    The eccentric ring  34  includes a flange  44 , a pivot hole  46 , and a pivot pin  47  received in the pivot hole  46 . The pivot hole  46  and pivot pin  47  connect the eccentric ring  34  to the housing  36 , so as to allow the eccentric ring  34  to pivot about the pivot pin  47 . The flange  44  is also connected to a bias mechanism such as a spring on one side, and a piston on the opposite side, such that force can be applied to the flange  44 , changing the eccentricity between the inner rotor  12  and the outer rotor  28 , the function of which will more clearly be described later. 
         [0024]    In operation, the inner rotor  12  is affixed to, and driven by a hub  48 . The inner rotor  12  turns and applies force to and drives the vanes  18 . The flat engagement  24  of the first end  20  and the second end  22  then applies force to the recesses  32  of the outer rotor  28 . Because the recesses  32  are located at an angle which is identical to the angle  27  of the vanes  18 , the recesses  32  are in flush contact with the flat engagements  24 , allowing the flat engagements  24  to apply force to the recesses  32 , and drive the outer rotor  28 . The outer rotor  28  is allowed to rotate relative to the eccentric ring  34  because of a hydrodynamic journal bearing  50  located therebetween. The hydrodynamic journal bearing  50  in this embodiment is a hydrodynamic film which minimizes friction between the outer rotor  28  and the eccentric ring  34 . However, the hydrodynamic journal bearing  50  could also be a ball bearing, a type of grease, or any other device which would reduce friction between the outer rotor  28  and the eccentric ring  34 . 
         [0025]    The pump  10  has the ability to vary the amount of fluid pumped from the inlet port  40  to the outlet port  42 . When the pump  10  is in the position shown in  FIG. 1 , the first axis  14  of the inner rotor  12  and the second axis  30  of the outer rotor  28  are aligned. When the first axis  14  is aligned with the second axis  30 , no fluid is transferred from the inlet port  40  to the outlet port  42 . As force is applied to the flange  44 , the eccentric ring  34  will pivot about the pivot pin  47  located in the pivot hole  46 . As the eccentric ring  34  pivots, the outer rotor  28  will move as well. The outer rotor  28  can be moved to a maximum position shown in  FIG. 2 . In this position, fluid will be drawn into the expandable chamber  38  and inbetween each of the vanes  18  from the inlet port  40  because the position of the outer rotor  28  and the expandable chamber  38  creates a suction as the inner rotor  12  and outer rotor  29  rotate, and the vanes  18  move across the inlet port  40 . 
         [0026]    As the inner rotor  12 , the outer rotor  14 , and the vanes  18  continue to rotate, the amount of fluid in the expandable chamber  38  will reach a maximum volume, and then the expandable chamber  38  will begin to compress the fluid. The expandable chamber  38  will compress the fluid between the vanes  18  even further as the inner rotor  12  and outer rotor  28  rotate, and the vanes  18  move across the outlet port  42 . The contraction of the fluid between each of the vanes  18  will force the fluid through the outlet port  42 . To compensate for the change in eccentricity between the outer rotor  28  and the inner rotor  12 , the flat engagement  24  of the vanes  18  are allowed to slide in the recesses  32 , while still transferring rotational force to the outer rotor  28 . 
         [0027]    Another aspect of the invention which provides advantages over previous vane pumps is that the vanes  18  are in a “stacked” configuration, which is best seen in  FIG. 3 . As previously mentioned, each vane  18  has an extension  26  formed as a portion of each vane  18 . The width of each extension  26  is narrower than the overall width of the vane  18 . Each extension  26  is also located in a different location along the width of the vane  18 . This allows the vanes  18  to “stack” together, allowing all the vanes  18  to be inserted into a corresponding slot  16  in the inner rotor  12 . In this particular embodiment, there are four vanes  18 : a first vane  52 , a second vane  54 , a third vane  56 , and a fourth vane  58 . 
         [0028]    As can be seen in  FIG. 3 , the extension  26  of the first vane  52  is adjacent to the extension  26  of the second vane  54 , the extension  26  of the second vane  54  is adjacent to the extension  26  of the third vane  56 , and the extension  26  of the third vane  56  is adjacent to the extension  26  of the fourth vane  58 . Each extension  26  is adjacent to one another, but will be at a different angle relative to one another because of each vane  18  being located in a corresponding slot  16  in the inner rotor  12 . 
         [0029]    The present invention is not limited to having four vanes  18 , as described above. The number of vanes  18  can be changed to suit any particular application requiring a sliding vane pump  10  of the present invention. In this embodiment, since there are four vanes  18 , the width of each extension  26  is approximately 25% of the total width of each vane  18 . If more or less vanes  18  were used, the width of the extension  26  would change proportionately. For example, if six vanes were used, each extension would be ⅙ of the total width of the vane  18 ; if two vanes  18  were used, the width of each extension  26  would be half of the total width of the vane  18 . 
         [0030]    The present invention has several advantages over other types of sliding vane pumps and articulated vane pumps. The sliding vane pump  10  of the present invention has a lower number of vanes  18 , but still performs as effectively, and has higher volumetric efficiency. Also, the vanes  18  having the flat engagements  24  driving the outer rotor  28  in the manner described by the present invention reduces the amount of wear on the flat engagements  24  and the outer rotor  28 , the amount of contact stress on the vanes  18  is also reduced when compared to a conventional sliding vane pump. The engagement between the flat engagements  24  of the vanes  18  and the recesses  32  also provides for the ability to prime the pump  10  at start up. This eliminates additional components such as guide rings and/or oil pressure, which are used to prime typical sliding vanes pumps. The pump  10  of the present invention is also facilitates easier assembly during manufacturing, and is more packaging efficient. The integrated structure of the vanes  18  also eliminates or reduces the centrifugal effect. Noise, vibration, and harshness (NVH) is improved because the vanes  18  are more dynamically balanced, and there is an increased resistance to contamination which can inhibit performance. 
         [0031]    An alternate embodiment of the present invention is shown in  FIGS. 7-10 , wherein like numbers refer to like elements. The pump  10  shown in  FIGS. 7-10  includes a straddle support inner rotor, generally shown at  60 . The inner rotor  60  also includes a series of slots  62 . However, the slots  62  of this embodiment differ from the first embodiment in that two of the slots  62  are elongated slots  64 , and two of the slots  62  are not elongated slots  66 . The inner rotor  60  also includes two hub portions  68 , and a series of vane supports  70 , which are used to support a series of vanes. 
         [0032]    In this embodiment, two of the vanes are multi-piece vanes  76 , and two of the vanes are single piece vanes  78 . The single piece vanes  78  are similar to the first vane  52  and fourth vane  58 , respectively, of the first embodiment. The multi-piece vanes  76  are similar to the second vane  54  and third vane  56 , respectively, with the exception that the multi-piece vanes  76  are divided into two parts. The extensions  26  are divided in half. 
         [0033]    During assembly, the multi-piece vanes  76  are inserted into the non-elongated slots  66 , and the single piece vanes  78  are inserted into the elongated slots  64 . The function of the elongated slots  64  is to allow the single piece vanes  78  to be inserted through the inner rotor  60 . More specifically, the elongated slots  64  allow the widest part of the vane  78  to be inserted through the rotor  60  without being blocked by or receiving any interference from the extensions  26  of any of the other vanes. Once the multi-piece vanes  76  and the single piece vanes  78  are inserted into the slots  62 , the rotor  60  is inserted into the outer rotor  28  in a similar manner as in the previous embodiment. The vanes will also engage the recesses  32  of the outer rotor  28  in a similar manner to the first embodiment. 
         [0034]    Once all of the vanes are inserted into the slots  62 , the housing  36  will prevent the vanes from sliding out of the slots  62  because the inside surface of the housing  36  will be in sliding contact with each of the vanes. 
         [0035]    The inner rotor  60  is supported on both sides of the vane supports  70  by the hub portions  68 ; this provides additional structural support and allows for an increased pressure capacity of the pump  10 . The inner rotor  60  is driven by the shaft; the rotor  60  turns and applies force to the vanes, and the vanes in turn apply force to the recesses  32 , driving the outer rotor  60  in a similar manner compared to the previous embodiment. 
         [0036]    To vary the amount of fluid that is pumped in this embodiment of the present invention, the flange  44  is inserted into a recess  80  of a piston  82 . The piston  82  includes a hollow portion  84  which receives a portion of a return spring  86 . On the opposite side of the piston  82  is a flat portion  88  which receives pressure from fluid. When the fluid pressure on the flat portion  88  of the piston  82  is greater than the pressure applied to the piston  82  from the return spring  86 , the piston  82  will move to the right when looking at  FIG. 7 , and the eccentric ring  34  will pivot in the same manner as the previous embodiment, and the amount of fluid pumped will decrease. When the fluid pressure on the piston  82  is relieved, the force applied to the piston  82  from the return spring  86  will cause the eccentric ring  34  to return to its original position to increase the displacement, as shown in  FIG. 7 , which is the default position for the eccentric ring  34 , where the first axis  14  is aligned with the second axis  30 . 
         [0037]    The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.