Patent Publication Number: US-6213744-B1

Title: Phased rotary displacement device

Description:
FIELD OF THE INVENTION 
     A phased trochoidal rotary chamber device which can be used for compression and expansion of fluid, pumping of liquid, or as a hydraulic motor. 
     BACKGROUND OF THE INVENTION 
     In U.S. Pat. No. 5,769,619, applicants described and claimed a rotary device comprised of a housing comprising a curved inner surface in the shape of a trochoid and an interior wall, an eccentric mounted on a shaft disposed within said housing, a first rotor mounted on said eccentric shaft which is comprised of a first side and a second side, a first pin attached to said rotor and extending from said rotor to said interior wall of said housing, and a second pin attached to said rotor and extending from said rotor to said interior wall of such housing, and a third pin attached to said rotor and extending from said rotor to said interior wall of said housing. This rotary device also contains the following features: (1) a continuously arcuate track is disposed within said interior wall of said housing, wherein said continuously arcuate track is in the shape of an envoluted trochoid, (2) said first pin has a distal end which is disposed within said continuously arcuate track, (3) said second pin has a distal end which is disposed within said continuously arcuate track, (4) said third pin has a distal end which is disposed within said continuously arcuate track, (5) said distal end of said first pin is comprised of a shaft disposed within a first rotatable sleeve, (6) said distal end of said second pin is comprised of a shaft disposed within a second rotatable sleeve, said distal end of said third sleeve is comprised of a shaft disposed within a third rotatable sleeve, (7) said rotor is comprised of a multiplicity of apices, wherein each such apex forms a compliant seal with said curved inner surface, and wherein each such apex is comprised of a separate curved surface which is formed from a strip of material pressed into a recess, (8) said curved inner surface of said housing is generated from an ideal epictrochoidal curve and is outwardly recessed from said ideal epitrochoidal curve by a distance of from about 0.05 to about 5 times as great as the eccentricity of said eccentric, (9) the diameter of the distal end of each of said first pin and said second pin is from about 2 to about 4 times as great as said eccentricity of said eccentric, and (10) each of said first pin, said second pin, and said third pin extends from beyond said interior wall of said housing by from about 1 to about 2 times the diameter of each of said pins. The entire disclosure of this U.S. Pat. No. 5,769,619 is hereby incorporated by reference into this specification. 
     It is an object of this invention to provide a trochoidal rotary chamber device which is more durable, more reliable, and more efficient than the trochoidal rotary chamber device described and claimed in U.S. Pat. No. 5,769,619. 
     SUMMARY OF THE INVENTION 
     In accordance with this invention, there is provided a rotary device comprised of a housing with a side plate, a shaft disposed within said housing, a rotor mounted on said shaft, and a set of meshing gears, one with internal teeth attached to the rotor, and the other with external teeth attached to the side plate of the housing, both of such gears being concentric to the element they are attached to. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will be described by reference to the specification and the enclosed drawings, in which like elements are identified by like numerals, and in which: 
     FIG. 1 is an exploded view of one preferred rotary mechanism of the invention; 
     FIG. 2 is partial sectional view of the mechanism of FIG. 1, illustrating the interaction between the rotor and external gear on the side plate of the housing; 
     FIG. 3 is a schematic representation of a trochoidal surface and an envoluted trochoidal surface produced by the device of this invention; 
     FIGS. 4,  5 ,  6 ,  7 , and  8  are schematic representations of a rotor with a solid curved surface, a strip seal, a spring-loaded seal, and a and a strip of material, as well as all of these structures, disposed at one or more of its apices sealing purposes. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The instant invention is comprised of an improvement on the structure disclosed in U.S. Pat. No. 5,769,619. 
     FIG. 1 is an exploded perspective view of one preferred rotary mechanism  10 . Referring to FIG. 1, it will be seen that rotary mechanism  10  is comprised of housing  12 , shaft  14 , rotor  16 , external gear  18 , internal gear  20 , eccentric  22 , bearing  24 , and side plate  26 . 
     Referring again to FIG. 1, it will be seen that housing  12  is preferably an integral structure. However, housing  12  may comprise two or more segments joined together by conventional means such as, e.g., bolts. 
     In one embodiment, housing  12  consists essentially of steel. As is known to those skilled in the art, steel is an alloy of iron and from about 0.02 to about 1.5 weight percent of carbon; it is made from molten pig iron by oxidizing out the excess carbon and other impurities (see, e.g., pages 23-14 to 23-56 of Robert H. Perry et al.&#39;s “Chemical Engineer&#39;s Handbook,” Fifth Edition (McGraw-Hill Book Company, New York, New York, 1973). 
     In another embodiment, housing  12  consists essentially of aluminum. In yet another embodiment, housing  12  consists essentially of plastic. These and other suitable materials are described in George S. Brady et al.&#39;s “Materials Handbook,” Thirteenth Edition (McGraw-Hill, Inc., New York, New York, 1991). 
     In another embodiment, housing  12  consists essentially of ceramic material such as, e.g., silicon carbide, silicon nitride, etc. 
     In one embodiment, housing  12  is coated with a wear-resistant coating such as, e.g., a coating of alumina formed electrolytically, electroless nickel, tungsten carbide, etc. 
     One advantage of applicant&#39;s rotary mechanism  10  is that the housing need not be constructed of expensive alloys which are resistant to wear; and the inner surface of the housing need not be treated with one or more special coatings to minimize such wear. Thus, applicants&#39; device is substantially less expensive to produce than prior art devices. 
     Housing  12  may be produced from steel stock (such as, e.g., C1040 steel stock) by conventional milling techniques. Thus, by way of illustration, one may use a computer numerical controlled milling machine which is adapted to cut a housing  12  with the desired curved surface. 
     Similarly, the rotor  16  may be made of any material(s) from which the housing  12  is made. 
     Referring again to FIG. 1, and in the preferred embodiment depicted therein it will be seen that housing  12  is comprised of an external gear  18  mounted on an inner wall  26  of such housing  12 . The external gear  18  is so disposed that, when drive shaft  14  is disposed therein, the gear  18  is concentric to the drive shaft  14 . 
     The external gear  18  preferably has a substantially circular cross-sectional shape. 
     In order for the external gear  18  and the internal gear  20  to phase properly the rotor  16  in the housing  12 , they have to meet two different conditions. In the first place, the difference between the two pitch diameters of the internal and external gears must be exactly twice the eccentricity of the shaft  22 . In the second place, the ratio between the pitch diameters of the internal and external gears must be the same as the ratio between the numbers of sides in rotor  16  divided by the number of lobes in housing  12 . These criteria will be discussed in more detail later in this specification. 
     The eccentricity of eccentric  22  generally will be from about 0.05 to about 10 inches. It is preferred that the eccentricity be from about 0.15 to about 1.5 inches. 
     Referring again to FIG. 1, and in the preferred embodiment depicted therein, it will be seen that bearing  24  can either be a sleeve bearing and/or a rolling element bearing. 
     Referring to FIG. 2, it will be seen that rotor  16  is comprised of a bore  28  with a center line  34  and an internal diameter  42 . The internal diameter  42  of bore  28  is smaller than the pitch diameter  30  of internal gear  20 . 
     As is known to those skilled in the art, the term pitch diameter refers to the diameter of an imaginary circle, which commonly is referred to as the “pitch circle,” concentric with the gear axis  34 , which rolls without slippage with a pitch circle of a mating gear. Reference may be had, e.g., to U.S. Pat. Nos. 5,816,788, 5,813,488, 5,704,865, 5,685,269, 5,474,503, 5,454,175, 5,387,000, and the like. The disclosure of each of these U.S. patents is hereby incorporated by reference into this specification. 
     Referring again to FIG. 2, it will be seen internal diameter  42  is also smaller than diameter  32  of the addendum circle of internal gear  20 . As is known to those skilled in the art, the addendum circle is a circle on a gear passing through the tops of the gear teeth. See, e.g., U.S. Pat. Nos. 5,438,732, 5,154,475, 5,090,771, 4,864,893, 4,813,853, 4,780,070, and the like. The entire disclosure of each of these U.S. patents is hereby incorporated by reference into this specification. 
     Referring again to FIG. 2, it will be seen that two internal gears  20  and  21  are depicted, one of which is disposed at end  46  of the rotor  16 , and the other which is disposed at end  48  of rotor  16 . In the preferred embodiment depicted, each of gears  20  and  21  is disposed within a counterbore ( 50  and  52 , respectively). In another embodiment, not shown, only one gear  20  or  21  is disposed on one side of rotor  16 . 
     The gears  20 , 21  may be attached to rotor  16  by conventional means such as, e.g., by mechanical means (using fasteners such as bolts, internal retaining rings, etc.), by interference fit, by electron beam welding, etc. 
     In the embodiment depicted in FIG. 1, the rotor  16  contains four sides and has a substantially square shape. As will be apparent to those skilled in the art, one may use rotors with 3 sides (not shown), 5 sides, 6 sides, etc. In general, it is preferred the rotor contain at least 3 sides and no more 6 sides. 
     Referring again to FIG. 2, it will be seen that an external gear  18  is disposed within side plate  26  and, more precisely, within counterbore  54  of side plate  26 . In the embodiment depicted, only one such external gear  18  is shown disposed on one side plate. In another embodiment, not shown, two such external gears are used and are disposed on both sides of rotor  16 . It will be apparent that, although only one side plate  26  is shown in FIGS. 1 and 2 for the sake of simplicity of representation, at least two such side plates generally are required for each housing, one for each side of the housing. 
     Referring again to FIG. 2, it will be seen that side plate  26  is comprised of a bore  50  with a centerline  40  and an internal diameter  44 . The internal diameter  44  of bore  50  is smaller than the pitch diameter  36  of external gear  18 . 
     It will be seen that internal diameter  44  is also smaller than the diameter  38  of the external gear  18 , which is the inner bore of external gear  18 . 
     The gear(s)  18  may be attached to side plate  26  by conventional means such as, e.g., by mechanical means (using fasteners such as bolts, internal retaining rings, etc.), by interference fit, by electron beam welding, etc. 
     As mentioned elsewhere in this specification, in order for the external gear  18  and the internal gear  20  to phase properly the rotor  16  in the housing  12 , two different conditions must be met. In the first place, the difference between the two pitch diameters of the internal and external gears (viz., pitch diameters  30 , and  36 ) must be exactly twice the eccentricity of the shaft  22 . In the second place, the ratio between the pitch diameters  30  and  36  of the internal and external gears must be the same as the ratio between the numbers of sides in rotor  16  divided by the number of lobes in housing  12 . 
     FIG. 3 is a schematic representation of trochoidal surface  82  and envoluted trochoidal surface  60  referred to in this specification. Referring to FIG. 3, and in the preferred embodiment depicted therein, it will be seen that surface  60  defines a multiplicity of lobes  62 ,  64 , and  66  which, in combination, define an inner surface  60  which has a continuously changing curvature. 
     Referring again to FIG. 3, it will be seen that, with regard to lobe  62 , the distance from the centerpoint  68  to any one point on lobe  62  will preferably differ from the distance from the centerpoint to an adjacent point on lobe  62 ; both the curvature and the distance from the centerpoint  68  is preferably continuously varying in this lobe (and the other lobes). Thus, for example, the distance  70  between point  68  and  72  is preferably substantially less than the distance  74  between points  68  and  76 ; as one progresses from point  72  to point  76  around surface  60 , such distance preferably continuously increases as the curvature of lobe  62  continuously changes. Thereafter, as one progresses from point  76  to point  78 , the distance  80  between point  68  and point  78  preferably continuously decreases. 
     Referring again to FIG. 3, it will be apparent to those skilled in the art that, in this preferred embodiment, the same situation also applies with lobes  66  and  64 . Each of such lobes is preferably defined by a continuously changing curved surface; and the distance from the centerpoint  68  is preferably continuously changing between adjacent points. 
     In the preferred embodiment illustrated in FIG. 3, it is preferred to have at least two of such lobes  62 ,  64 , and  66 . It is more preferred to have at least three of such lobes. In another embodiment, at least four of such lobes arc present. 
     It is preferred that each lobe present in the inner surface  60  have substantially the same curvature and shape as each of the other lobes present in inner surface  60 . Thus, referring to FIG. 3, lobes  62 ,  64 , and  66  are displaced equidistantly around centerpoint  68  and have substantially the same curvature as each other. 
     The curved surface  60  may be generated by conventional machining procedures. Thus, as is disclosed in U.S. Pat. No. 4,395,206, the designations “epitrochoid” and “hypotrochoid” surfaces refer to the manner in which a trochoid machine&#39;s profile curves are generated; see, e.g., U.S. Pat. No. 3,117,561, the entire disclosure of which is hereby incorporated by reference into this specification. 
     An epitrochoidal curve is formed by first selecting a base circle and a generating circle having a diameter greater than that of the base circle. The base circle is placed within the generating circle so that the generating circle is able to roll along the circumference of the base circle. The epitrochoidal curve is defined by the locus of points traced by the tip of the radially extending generating or drawing arm, fixed to the generating circle having its inner end pinned to the generating circle center, as the generating circle is rolled about the circumference of the base circle (which is fixed). 
     In one embodiment, the epitrochoidal curve is generated in accordance with the procedure illustrated in FIG. 29 of U.S. Pat. No. 5,431,551, the entire disclosure of which is hereby incorporated by reference into this specification. 
     As is disclosed on lines 36 to 55 of column 5 of U.S. Pat. No. 4,395,206, it is common practice to recess or carve out the corresponding profile of the epitrochoid member a distance “x” equal to the outward offset of the apex seal radius (see FIG. 4 of such patent). As is stated on lines 48 et seq. in such patent, in “. . . the case of an inner envelope type device 20′, as shown in FIG. 4, such carving out requires that the actual peripheral wall surface profile 33 which defines the cavity 34 of the housing 35 be everywhere radially outwardly recessed from the ideal epitrochoid profile 36. In the case of an outer envelope device 21′, as illustrated in FIG. 5, such carving out requires that the actual peripheral face profile of the epitrochoid working member, rotor 38, be everywhere inwardly radially recessed from the ideal epitrochoid profile 39.” 
     Referring again to FIG. 3, it will be seen that applicants&#39; inner housing surface profile  60  is generated from ideal epitrochoid curve  82  and is outwardly recessed from ideal curve  82  by a uniform distance  84 . In one preferred embodiment, uniform distance  84  is a function of the eccentricity of the eccentric  22  used in device  10  (see FIG.  1 ). 
     Referring again to FIG. 1, it will be seen that rotary mechanism  10  is comprised of a shaft  14  on which the eccentric  22  is mounted. Shaft  14  preferably has a circular cross-section and is cylindrical in shape. Shaft  14  is connected to eccentric  22 . In one embodiment, illustrated in FIG. 1, shaft  14  and eccentric  22  are integrally formed and connected. 
     In one preferred embodiment, both shaft  14  and eccentric  22  consist essentially of steel such as, e.g., carbon steel which contains from about 0.4 to about 0.6 weight percent of carbon. 
     FIG. 4 of U.S. Pat. No. 5,431,551 is a front view of the shaft/eccentric assembly of this patent, and discussion is presented in such patent of the eccentricity of such assembly. As is known to those skilled in the art, eccentricity is the distance of the geometric center of a revolving body (eccentric  22 ) from the axis of rotation. 
     Referring again to FIG. 3, and in the preferred embodiment illustrated therein, it is preferred that the distance  84  be from about 0.5 to about 5.0 times as great as the eccentricity of eccentric  22  (see FIG.  1 ). In a more preferred embodiment, the distance  84  is from about 1.0 to about 2.0 times as great as the eccentricity. In one embodiment, distance  84  is about 0 times as great as the eccentricity. 
     FIG. 6 is a perspective view of a rotor assembly  10  in which the apices  86 ,  88 ,  90 , and  92  are not directly contiguous with the inner surface  56  of housing  12 . In this embodiment, inner surface  56  defines a theoretical trochoidal shape  82  (see FIG.  5 ). 
     The apparatus  10  may comprise one or more of apex seals disclosed in FIG. 6 of U.S. Pat. No. 5,769,619, the entire disclosure of which is hereby incorporated by reference into this specification. Thus, FIGS. 4,  5 ,  6 ,  7 , and  8  depict rotor(s)  16  with different types of scaling surfaces on each of its apices. In these Figures, for the sake of simplicity of representation, the external gear(s)  18  has been omitted. 
     Referring to FIG. 5, it will be seen that apex  118  is preferably a solid curved surface which is made from the same material as is rotor  16 . In this embodiment, the apex  118  is non-compliant, it provides close-clearance sealing at a distance of from about 0.0001 to about 0.002 inches from the inner surface of the housing (not shown), and it will describe an envoluted trochoidal geometry during its operation. 
     Referring to FIG. 6, apex  120  is connected to an apex seal  121 . In the embodiment depicted, apex seal  121  is a linear strip seal which is disposed within rotor  16 . Linear strip seal  121  can be metallic or non-metallic. 
     In one embodiment, where apex seal  121  is a fixed strip of material, it provides close-clearance sealing at a distance of from about 0.001 to about 0.002 inches away from the inner surface of the housing and describes an ideal trochoidal geometry during its operation. In another embodiment, where the seal  121  is made compliant by conventional means, it provides substantially zero clearance sealing and also describes an ideal trochoidal geometry during its operation. 
     Referring to FIG. 7, apex  122  is comprised of a separate curved surface  123  affixed to apex  122  and made complaint by virtue of the presence of spring  125 . In this embodiment, the apex  122  provides substantially 0 clearance sealing and describes an envoluted trochoidal geometry during its operation. The surface  123  may consist of an ultra-high molecular weight plastic. 
     Referring to FIG. 8, apex  124  is comprised of a separate curved surface  127  which is formed from a strip of material pressed into a recess (not shown) in rotor  16 . If this curved surface  127  is made from compliant material, apex  124  will also be compliant during operation, thereby providing substantially zero clearance, and will describe an envoluted trochoidal geometry during its operation. A port (not shown) communicating with the pressurized portion of a pressurized volume (not shown) may be employed to pressurize the back the curved surface  127 , such that improved clearance control is achieved at higher pressures. In a similar manner, an equalizing pressure can also be applied to linear strip seal  121  (see FIG. 6) and/or surface  123  (see FIG.  7 ). 
     FIG. 4 illustrates an embodiment in which each of the different apex sealing means described above exist with reference to one particular rotor  16 . It will be apparent that other combinations of sealing means besides the ones depicted also may be used. 
     It is to be understood that the aforementioned description is illustrative only and that changes can be made in the apparatus, in the ingredients and their proportions, and in the sequence of combinations and process steps, as well as in other aspects of the invention discussed herein, without departing from the scope of the invention as defined in the following claims.