Abstract:
A rotary piston for use in pumps or motors, the piston having a radially movable vanes seated within the pumps rotor. The vanes are biased outwardly and forced inwardly by a cam action of the interior wall of the housing of the piston. Operation of the piston may be facilitated by the use of peripherally mounted drive gears. The rotary piston according to the present invention is particularly useful in pumping fluids and provides a system that can operate at both high and low speeds for a wide range of liquid viscosities.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates to improved rotary pistons for use in pumps or motors.  
       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 side 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 “motors” require centrifugal force, through rotation of the rotor, to force the vanes out.  
         [0005]     Problems with such arrangements, if applied to hydraulics, 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]     It is an object of the present invention to provide a hydraulic pump for liquid or air which will operate efficiently and effectively at medium or high pressures and handle high fluid volumes and high torque at low, medium or high fluid pressure. It is also an object of the present invention to provide a simpler construction of rotary piston which provides for outward vane movement, from the rotor, at lower rotor speeds and without the need for cam surfaces or races within the casing, thereby providing a simpler and more economical construction for rotary pistons.  
       SUMMARY OF THE INVENTION  
       [0007]     In accordance with the present invention there is provided a rotary piston which comprises a shaft to rotate about a longitudinal axis, and a rotor centrally secured to the shaft. The rotor has ends and a cylindrical side wall. A rotor disk is secured at each end of the rotor to rotate with the rotor. A housing encases the rotor and has interior end walls confronting the rotor ends and an interior side wall opposite the rotor end wall. Fluid inlet and fluid outlet ports are located in the housing side wall. 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 cylindrical portion of the interior side wall of the housing extends between the extremities of the first portion of the interior side wall and is of curvature of greater radius. The wall of the rotor meets the interior side wall of the housing at a point between inlet and outlet ports about midway on the second portion. The inlet and outlet ports are spaced from each other in the second portion of the interior side wall of the housing. Two or more planar vanes extend from end to end in the rotor and have inner and outer edges extending parallel to the axis of the rotor. Each vane is movable in slots in the rotor radially inwardly and outwardly between retracted and extended positions with respect to the cylindrical side wall of the rotor. The vanes have side shoulders which slide in corresponding guide slots in the rotor disks. The outer edges of the vanes are positioned adjacent to the interior side wall of the housing. The housing side wall exerts a cam action on these outer edges. The vanes are equally spaced from adjacent vanes about the rotor such that there is always at least one vane positioned between inlet and outlet ports. Biasing means are provided to urge each of the vanes radially within its associated slot towards extended position, so that during operation, the outer edge of each vane is constantly positioned adjacent a corresponding portion of the interior side wall of the housing. The rotor, housing and vanes are constructed so that, during operation of the pump, fluid entering the housing 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 adjacent vanes encompass the outlet port whereby the fluid is allowed to escape.  
         [0008]     In a preferred embodiment of the present invention a rotary piston where two or more spaced pins are secured within each rotor slot. Each pin extends radially in its slot. Corresponding pockets are provided in the inner edge of corresponding vanes to slidably receive the pins. A spring is seated within each pocket to bear against the corresponding pin in a manner so as to provide the biasing of the vanes.  
         [0009]     As well, in another preferred embodiment of the present invention, the outer edge of each vane is convexly rounded and extends outwardly beyond planar faces of the vane, between the shoulders, to form a linear, mushroom-shaped head of the vane. The rotor slot for each corresponding vane has a corresponding enlargement for receiving the vane&#39;s head such that the outer edge is housed within that groove when the vane is in retracted position.  
         [0010]     The device 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 outer 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 pumps, compressors and motors. The rotary piston according to the present invention is particularly effective in pumping fluids with higher viscosities. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]     These and other advantages of the invention will become apparent upon reading the following detailed description and upon referring to the drawings in which:— 
         [0012]      FIG. 1  is a schematic side section view of an example embodiment of rotary piston according to the present invention;  
         [0013]      FIG. 2  is a partial, perspective view of a rotor, and disk and (exploded) vane of the rotary piston of  FIG. 1 ;  
         [0014]      FIG. 3  is a perspective view, in partial section, of the rotary piston of  FIG. 1 ;  
         [0015]      FIG. 4  is a side section view of the rotary piston of  FIG. 1 , in partial phantom, illustrating a gear drive mechanism for the piston;  
         [0016]      FIG. 5  is a partial view, in section, of an upper portion of the rotary piston of  FIG. 3 ; and  
         [0017]      FIG. 6  is a partial view, again in section, of upper portion of an alternative embodiment of rotary piston in accordance with the present invention.  
     
    
       [0018]     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  
       [0019]     In the following description, similar features in the drawings have been given similar reference numerals.  
         [0020]     Turning to  FIG. 1 , there is illustrated a rotary piston  2  in accordance with the present invention. The piston comprises a shaft  4  rotating about a longitudinal axis, on which shaft a rotor  6  is centrally secured. Rotor  6  has a body with a cylindrical side wall  8  extending between spaced ends  10 . A rotor disk  12  is provided at each end of rotor  6 , each disk secured at its center to shaft  4  and to the corresponding end  10  of rotor  6 . Shaft  4 , rotor  6 , and rotor disks  12  may be of integral construction. It is preferred that the diameter of disks  12  be greater than that of rotor  6 .  
         [0021]     A housing  14  encases rotor  6  and rotor disks  12  within an internal cavity  16 . Shaft  4  extends outside housing  14 , as illustrated ( FIGS. 3 and 5 ). Housing  14  has end walls  18  adjacent to rotor disks  12  and an interior side wall  20 . Fluid inlet port  22  and fluid outlet port  24  are provided in side wall  20 .  
         [0022]     As can be seen in  FIG. 1 , first portion  26  of the interior sidewall  20  is cylindrical and curved with constant radius over an angle of about 180°. This portion is spaced a constant distance from corresponding portions of the cylindrical side wall  8  of rotor  6 . A second cylindrical portion  28  of the interior side wall  20  extends between the extremities of this first portion  26  of the interior side wall. Portion  28  has a curvature of greater radius than that of the first portion.  
         [0023]     Two or more (four are illustrated) equally spaced, radially oriented slots  30  in rotor  6  extend end to end across its cylindrical side wall  8 . This cylindrical side wall  8  is proximal to the interior sidewall  20  of the housing at a point  32  on portion  28 , about midway between the inlet and outlet ports  22  and  24 . Inlet and outlet ports  22  and  24  are located in this second portion  28 .  
         [0024]     Two or more (again, four are illustrated) similar vanes  34  are slidably seated in the slots  30  of rotor  6  as illustrated. Each vane  34  has an inner edge  36  and an outer edge  38  extending between sides  40  of the vanes. Each vane  34  is movable radially in its corresponding slot between an extended position with the outer edge  38  of the vane adjacent first portion  26  of the interior sidewall of the housing and a retracted position, when the vane passes point  32 , where that outer edge  38  is retracted and does not extend beyond the cylindrical surface of side wall  8  of the rotor. The vanes  34  are spaced from each other about the rotor such that there is always at least one vane positioned between the inlet and outlet ports  22  and  24 . Sides  40  of vanes act as shoulders  42  which slide in corresponding guide slots  44  in the rotor disks  12 . As can be seen in  FIG. 1 , outer edges  38  of vanes  34  are always positioned adjacent interior side wall  20  of housing  14 , this side wall  20  exerting a cam action on those outer edges, to move the vanes to retracted position. Vanes  34  are spaced equally from adjacent vanes  34 , about rotor  6 , and are located so that there is always at least one vane positioned between inlet port  22  and outlet port  24 .  
         [0025]     In order to ensure outward movement of vanes  34  and the biasing of those vanes so that they are always in contact with corresponding portions of inner side wall  20  of housing  14 , springs  46  are provided. These springs are held in pockets  48  which extend upwardly, as illustrated, from the internal edge  36  of each vane  34 . Two or more such springs  46  and pockets  48  are located in spaced fashion, as illustrated, in each vane  34 . Secured to the bottom of each slot  30  in rotor  6 , and positioned so as to be mateably received in vane pockets  48 , are pins  50 . Springs  46  are held within pockets  48  by these pins  50 , and bear against the pins and the bottoms of the respective pockets so as to provide appropriate upward bias to the vanes in their corresponding rotor slots  30 . During operation, the outer edge  38  of each vane  34  is constantly positioned against a corresponding portion of the interior side wall  20  of housing  14 . The rotor  6 , housing  14  and vanes  34  are constructed so that, during operation of the rotary piston, fluid entering housing  14  is carried by rotor  6  in compartments  52  formed between adjacent vanes  34 , rotor cylindrical side wall  8  between those vanes, the rotor disks  12  and the corresponding portions of the interior side wall  20  of housing  14 , until these adjacent vanes encompass the outlet port  24 , at which point fluid in that compartment  52  is allowed to escape through outlet port  24 .  
         [0026]     As can be seen in  FIGS. 1 and 2 , outer edge  38  of each vane is convexly rounded and extends outwardly beyond planar faces  54 , on each side of the vane, between shoulders  42 , to form, as illustrated, a linear, mushroom-shaped head  56  of the vane. The cylindrical side wall  8  of rotor  6  has a corresponding enlargement  58  formed such that, when outer edge  38  of the vane is in retracted position, head  56  is housed within that enlargement  58 , beneath the cylindrical side wall of rotor  6 . As well, an elongated slot  60  ( FIG. 1 ) extends from side to side, as illustrated, in each head  56 , and a seal  62  ( FIG. 2 ) is seated in that slot, the seal restricting the leakage of fluid between adjacent compartments  52  during operation of the pump. As illustrated, for example, in  FIGS. 2 and 5 , it is preferred that shoulders  42  have extensions  63  going beyond head  56 . These extending portions of the shoulders in fact extend outwardly beyond inner side wall  20  of housing  14  sliding in slots  44  in rotor disks  12  and assist in restricting leakage of fluid from chambers  52  during operation of the device.  
         [0027]     To facilitate functioning of the rotary pump in accordance with the present invention, as illustrated particularly in  FIGS. 5 and 6 , either a regular drive gear  64  ( FIGS. 4 and 5 ) or a crown drive gear  66  ( FIG. 6 ) may be associated with a peripheral portion of one or both of the rotor disks  12 . As can be seen in  FIGS. 4 and 5 , teeth  67  of drive gear  64  drive teeth  68  which have been formed on the outside circumference of rotor disk  12 . Gear  64  is preferably positioned between inlet and outlet ports  22  and  24 , as illustrated. As illustrated in  FIG. 3 , a pair of drive gears  64  may be provided, one running on gear teeth  68  on each of the rotor disks  12 , off a common shaft  70  in this embodiment. Larger diameter end disks  12  than otherwise would be required, are needed to provide adequate clearance for the operation of drive gear  64 .  
         [0028]     In the alternative embodiment illustrated in  FIG. 6 , the teeth  71  of crown gear  66  mesh with gear teeth  72  on annular projection  74  about the periphery of rotor disk  12 , that projection facing housing end wall  18  as illustrated. This embodiment does not require such a large diameter rotor disk  12 . Again it is preferred that crown gear  66  be located between inlet and outlet ports  22  and  24 .  
         [0029]     The drive gear system as described allows the rotor to be driven by a high speed motor while keeping the rotor rpm&#39;s lower, resulting in an increased torque being applied to movement of fluids by the rotor vanes  34 .  
         [0030]     The rotary piston according to the present invention is particularly useful in pumping fluids and provides a system that can operate at both high and low speeds, for a wide range of liquid viscosities and even gases.  
         [0031]     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.