Abstract:
A rotary piston pump comprising a rotor mounted within a housing, the rotor having a pair of slidably mounted vanes on opposite surfaces. The inner wall of the housing acts as a cam surface to move the vanes inwardly, and centrifugal force or a combination of centrifugal force and biasing causes the vanes to move outwardly. The rotor is eccentrically mounted within the housing and the housing interior walls are of irregular configuration, whereby fluid from an inlet is moved by the vanes through the housing to an outlet. This rotary piston pump is of economic construction, serves a variety of applications and is easy to service.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates to a novel construction of positive displacement pump for fluids, and more particularly to a rotary piston pump.  
       BACKGROUND OF THE INVENTION  
       [0002]     Rotary pistons, in the nature of encased rotors with radially extending vanes which move in and out of the rotors, depending upon their location within the casing used, for example, as pumps or turbines, are known. One such device is described in U.S. Pat. No. 6,554,596 of Albert and David Patterson issued Apr. 29, 2003, in which the vane movement, in and out of the rotor, is achieved by cam surfaces within the casing which act on both inner and outer edges of the vanes.  
         [0003]     In my co-pending U.S. patent application Ser. No. 10/680,236 entitled “Rotary Pistons”, the outward movement of the vanes is achieved by upward extensions of shoulders at the sides of each vane, which upward extensions contain pins which are seated in races continuously extending in portions of the interior wall of the casing and positioned so that as the pins move about the races, they draw their respective vanes outwardly.  
         [0004]     Other known constructions of such vane pumps require centrifugal force, through rotation of the rotor, to force the vanes out.  
         [0005]     Problems with such arrangements, if applied to pumps, include leakage of fluid between the vanes and consequent inability to effectively and efficiently handle fluids under high pressure. Of necessity, such devices have conventionally been of relatively small size, and, while they have been able to operate at fast speeds, they have been able to move only relatively low volumes of fluid.  
         [0006]     Traditionally, positive displacement pumps have been of relatively complex construction and have been limited in their applications.  
         [0007]     It is an object of the present invention to provide a positive displacement pump which is relatively economical to construct and efficient in its operation, which will be able to withstand high pressures and which will have a variety of applications.  
       SUMMARY OF THE INVENTION  
       [0008]     In accordance with the present invention there is provided a positive displacement pump for fluids which pump comprises a housing defining a chamber having opposed, interior end walls and an interior side wall. A fluid inlet port and a fluid outlet port are located at spaced locations in the interior side wall. A rotor to rotate about a longitudinal axis extending through the end walls is mounted within the housing chamber, the rotor having ends and a cylindrical side wall confronting respectively the interior end walls and side wall of the chamber. A rotor disk is provided at each end of the rotor secured to the rotor, the diameter of the rotor disks being greater than the diameter of the rotor. A slot extends diametrically completely through the rotor, longitudinally between the rotor ends. The slot has openings in opposite portions of the rotor side wall.  
         [0009]     A pair of similar, planar vanes are provided, one vane slidably mounted in one opening of this slot and the other mounted in the other opening of the slot. Each vane extends from end to end in the rotor and has inner and outer edges extending parallel to the axis rotation of the rotor. Each vane is mounted so as to slide within the slot between an extended position protruding upwardly from a surface of the rotor side wall and a retracted position wherein the vane is entirely withdrawn into the rotor below that surface. Each vane is provided with opposite shoulders at their sides, which shoulders slide in corresponding slots in the rotor disks.  
         [0010]     A first portion of the interior side wall of the housing is cylindrical and curved with constant radius over an angle of approximately 180°. This portion is spaced a constant distance from corresponding portions of the side wall of the rotor. A second portion of the interior side wall of the housing, in the vicinity of the outlet port, extends from an extremity of the first portion so as to be progressively closer to the rotor side wall until it is immediately adjacent to that side wall at a point beyond the outlet port intermediate between the outlet port and inlet port. A third portion of the interior side wall of the housing, in the vicinity of the inlet port, extends from the midpoint to the other extremity of the first portion of the interior end wall. The distance between the third portion and the side wall of the rotor progressively increases between the midpoint and the other extremity of the first portion.  
         [0011]     The rotor, housing and vanes are constructed so that, during operation of the pump, fluid entering the housing through the inlet port is carried by the rotor in compartments formed between adjacent vanes, the rotor side wall between those vanes, the rotor disks and the interior side wall of the housing, until the compartments communicate with the outlet port, whereby the fluid is moved from the chamber through the outlet port. The vanes, during this operation, are urged outwardly so that their outer edges are in constant contact with the interior side wall of the housing and being urged inwardly by the housing side wall acting as a cam surface on said outer edges.  
         [0012]     In a preferred embodiment of the present invention, the outer edges of the vanes are enlarged to form heads which provide additional weight to the vanes. The vanes&#39; outward movement is caused by centrifugal force during operation of the pump. The opening of the slot, on each side of the rotor, is enlarged to receive the enlarged head of the corresponding vane when the vane is in retracted position.  
         [0013]     In another embodiment, biasing means are provided between the inner edges of the vanes within the vane slot to provide outward biasing of the vanes during operation of the device and to ensure constant contact of the outer edges of the vanes with the inner side wall of the housing.  
         [0014]     The pump according to the present invention, while providing many of the same advantages of applicant&#39;s previously developed rotary pistons, is simpler and more economical to construct, since the extending vane movement does not require end cams or races to activate and guide that movement. The present invention has a wide range of applications including pumping waste water or well water, and as a hydraulic pump. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]     These and other advantages of the invention will become apparent upon reading the following detailed description and upon referring to the drawings in which:— 
         [0016]      FIGS. 1   a ,  1   b  and  1   c  are schematic side section views of an example embodiment of a positive displacement rotary piston pump according to the present invention;  
         [0017]      FIG. 2  is a perspective view of the rotor and end disk construction of the pump according to  FIG. 1 ;  
         [0018]      FIGS. 3 and 4  are perspective views of example embodiments of vanes usable in association with the rotor and end disk, in accordance with the present invention;  
         [0019]      FIG. 5  is a perspective view of a further embodiment of vane in accordance with the present invention; and  
         [0020]      FIG. 6  is a perspective view, in section, of the rotor and end disk of the pump of  FIG. 1 . 
     
    
       [0021]     While the invention will be described in conjunction with illustrated embodiments, it will be understood that it is not intended to limit the invention to such embodiments. On the contrary, it is intended to cover all alternatives, modifications and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims.  
       DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0022]     In the following description, similar features in the drawings have been given similar reference numerals.  
         [0023]     Turning to  FIGS. 1   a ,  1   b ,  1   c , there is illustrated a pump  2  in accordance with the present invention, at sequential stages of its operation. Pump  2  has a housing  4  with an inlet port  6  and outlet port  8  spaced to one side of it and communicating with an interior chamber  10  defined by a side wall  12  extending between opposite end walls  14 . Mounted within housing  4 , for rotation about a longitudinal axis extending between end walls  14  (phantom,  FIG. 2 ) is a rotor  16  and associated end disks  18 . End disks  18  may be secured to rotor  16  or may be integral therewith. The diameters of end disks  18 , as can be seen, are greater than the diameter of rotor  16 . Rotor  16  has a side wall  20  of elongated, cylindrical configuration. Diametrically positioned within rotor  16  is a vane slot  22  which passes through rotor  16  and extends from end to end. Corresponding slots  24  are provided in end disks  18 , aligned with vane slot  22  and extending beyond that slot, as illustrated. Mounted within vane slot  22 , for cooperative sliding movement on opposite sides of rotor  16 , is a pair of vanes  26 .  
         [0024]     Interior side wall  12  of housing  4 , as can be seen in  FIGS. 1   a ,  1   b  and  1   c  is carefully configured so as to act as a cam surface guiding vanes  26 , for proper operation of pump  2 . In particular, a cylindrical first portion  28  of side wall  12 , over about 180°, is provided. Rotor  16  is positioned within interior chamber  10  so that the surface of its side wall  20  is the same distance from this first portion  28  of housing interior side wall  12 . A second portion  30  of interior side wall  12  extends from one extremity of first portion  28  to a midpoint  32  between inlet and outlet port  6  and  8 , this portion being contoured so that its surface progressively approaches the surface of side wall  20  of rotor  16  until, at midpoint  32 , those two surfaces are contiguous or immediately adjacent to each other. This second portion  30  extends across outlet port  8 .  
         [0025]     A third portion  34  of interior side wall  12  extends from this midpoint  32  to the other extremity of first portion  28  in a manner such that the distance between third portion  34  and corresponding portions of the rotor surface progressively increase. Portion  34  extends across inlet port  6 .  
         [0026]     The rate at which this distance to the surface of rotor  16  progressively increases and decreases for portions  30  and  34  may be adjusted for specific applications and desired efficiencies of the pump.  
         [0027]     Passing through rotor  16 , preferably at a 90° angle to vane slot  22 , are one or more vent slots  36 , communicating with the interior chamber  10  of housing  4  and with vane slot  22 . A pair check valves  38  are provided in vent slot  36  as illustrated, to enable one way passage of fluid, outwardly, from vent slot  36 , to the surface of rotor  16 .  
         [0028]     Vanes  26  have a planar body  40 , upper edges  42  and lower edges  44 . The height of the vanes, between upper and lower edges  42  and  44 , is such that, during operation of the pump, the movement of one vane does not obstruct the movement of the other. Vanes  22  extend from end to end of rotor  16 , and beyond with their shoulders  46  slidably received in end disk slots  24 . Vanes  26  slide within vane slot  22  between retracted and extended positions, upper edges  42  being at all times in contact with side wall  12 . Each of the vanes  22  is provided with enlarged head  48 , the surface of which is rounded to conform with the cylindrical surface of side wall  12  of rotor  16  when the vane is in retracted position. A suitable cavity  50  is provided at each entrance to vane slot  22 , as illustrated, to flushly receive head  48  when vane  26  is in retracted position. It is preferred that a resilient seat  52  be provided over the sides of cavity  50 , so as to provide a sealing function to reduce the amount of fluid which would enter vane slot  22  from contacting surfaces of vane  26 , and to act as a shock absorber to cushion the impact of head  48  against rotor  16  as vane  26  reaches its retracted position. The enlarged head  48  of vanes  26  provides additional weight to ensure that centrifugal force, as rotor  16  rotates during operation of the device, keeps the upper edge  42  of each vane  26  bearing against side wall  12  of housing  4 .  
         [0029]     Different configurations of vanes  26  in accordance with the invention are illustrated in  FIGS. 3, 4  and  5 . While the enlarged head vane of  FIG. 5  has been described previously herein, the vanes  26  of  FIGS. 3 and 4  are constructed so as to provide an outward, spring induced bias to supplement the outward centrifugal force acting on the vanes during operation of the pump. In particular, each vane  26  cooperates with a shoe plate  54  at its lower edge  44 , the shoe plate being provided with spring loaded pins  56  ( FIG. 3 ) or a spring loaded plate  58  ( FIG. 4 ), these pins and plates slidably movable within corresponding apertures in the lower edge  44  of the corresponding vane  26 . The pins and plates also further assist in guiding the vanes in their reciprocating movement within vane slot  22 .  
         [0030]     A removable panel  60  may be provided in housing  4  to provide servicing access to chamber  10  and the pump components within chamber  10 .  
         [0031]     In operation, as can be seen in  FIGS. 1   a ,  1   b  and  1   c , as rotor  16  is driven in clockwise fashion, centrifugal force (in combination with the outward spring urged bias on vanes  26 , if the vane embodiment of  FIG. 3  or  4  is used) ensures that the upper edges  42  of vanes  26  constantly bear against the relevant first, second and third portions  28 ,  30  and  34  respectively, of side wall  12  of housing  4 . The inlet and outlet ports  6  and  8  are on opposite sides of midpoint  32 . Side wall  20  of rotor  16  is in contact with side wall  12  of housing  4 , at midpoint  32 , ensuring that fluid from inlet port  4  does not escape directly to outlet port  8 . Instead, fluid from inlet port  6  is drawn into chamber  62  ( FIG. 1   a ) as one of the vanes  26  passes over inlet port  6  and progresses to first portion  28  of side wall  12  of housing  4 . Side wall  12  at all times acts as a cam surface on upper edges  42  of the vanes  26 . As the rotor  16  continues in clockwise fashion, the other vane  26  passes over inlet port  6 . Chamber  62  then becomes sealed off and is at maximum volume ( FIG. 1   a ). With further clockwise movement of rotor  16 , as the first vane  26  passes outlet port  8  ( FIG. 1   b ), that chamber  62  then communicates with outlet port  8  and, as the volume of chamber  62  decreases with further clockwise movement of rotor  16  (with the decreasing distance of second portion  30  of side wall  12  of housing  4  with respect to the surface of side wall  20  of rotor  16 ), fluid is forced with the diminishing volume of that chamber  62  through outlet port  8 .  
         [0032]     Fluid which enters vane slot  22  is not permitted to build up there as it is passed back to the surface of rotor  16  through check valves  38  in vent slots  36 .  
         [0033]     Because of the relatively simple construction of the pump according to the present invention, with only two vanes and few moving parts, a pump which is inexpensive to construct and easy to repair is provided. The construction of the pump according to the present invention permits high torque on the rotor and high volume fluid movement since the shaft which drives the rotor can be the same diameter as that of the rotor.  
         [0034]     The pump of the present invention is particularly suited to waste water, well water, hydraulics and other applications. If solids are entrapped in fluid being pumped, and get into interior chamber  10 , the enlarged heads  48  of vanes  26  will tend to crush the solids to smaller sizes so that those solids will pass through the pump  2 .  
         [0035]     The pump according to the present invention withstands high pressure, since the shoulders  46  of the vanes  26  are supported by the end disks  18 . The simple construction of the pump according to the present invention permits it to be easily serviced and repaired in the field.  
         [0036]     Thus, it is apparent that there has been provided in accordance with the invention a rotary piston device that fully satisfies the objects, aims and advantages set forth above. While the invention has been described in conjunction with illustrated embodiments thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art in light of the foregoing description. Accordingly, it is intended to embrace all such alternatives, modifications and variations as fall within the spirit and broad scope of the invention.