Patent Application
20050254983
The present invention relates to improved rotary pistons for use in pumps or motors.
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.
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.
Other known constructions of such vane “motors” require centrifugal force, through rotation of the rotor, to force the vanes out.
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.
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.
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.
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.
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's head such that the outer edge is housed within that groove when the vane is in retracted position.
The device according to the present invention, while providing many of the same advantages of applicant'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.
These and other advantages of the invention will become apparent upon reading the following detailed description and upon referring to the drawings in which:—
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.
In the following description, similar features in the drawings have been given similar reference numerals.
Turning to
A housing 14 encases rotor 6 and rotor disks 12 within an internal cavity 16. Shaft 4 extends outside housing 14, as illustrated (
As can be seen in
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.
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
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.
As can be seen in
To facilitate functioning of the rotary pump in accordance with the present invention, as illustrated particularly in
In the alternative embodiment illustrated in
The drive gear system as described allows the rotor to be driven by a high speed motor while keeping the rotor rpm's lower, resulting in an increased torque being applied to movement of fluids by the rotor vanes 34.
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.
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.
