Abstract:
An electrically driven stepmotor valve assembly including separable annular stator and rotor-valve assemblies. The rotor-like assembly having a cylindrical housing adapted to slip fit inside a central, domed, stator cavity, with alignable locking members on these assemblies permitting rotary interlocking upon the slip fit assembly thereof. A sealing arrangement, in the vicinity of the open end of the stator assembly, peripherally seals the stator and rotor-valve assemblies relative to each other, when assembled, with the rotor housing having a locating plate ring portion which, in turn, supports an elastic sealing member that fits into a groove in a bottom wall of the stator housing. A plurality of differing sealing arrangement designs and structures, including sealing member reinforcing structures, are set forth for the sealing of the interlocked stator and rotor-valve assemblies relative to each other.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]     The present application claims the benefit of the filing date of U.S. Provisional Patent Application Serial No. 60/650,828, filed Feb. 8, 2005, the disclosure of which is incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The present invention pertains to a stepmotor valve assembly that includes separable stator and rotor-valve assemblies. The rotor-valve assembly may be fixedly secured to an apparatus and has a housing adapted to slip fit inside a stator cavity. Locking members on the noted assemblies permit rotary interlocking upon the slip fit assembly and relative rotation thereof. A plurality of differing sealing arrangements located in the vicinity of an open end of the stator assembly permit the sealing of the interlocked stator and rotor-valve assemblies relative to each other.  
       BACKGROUND OF THE INVENTION  
       [0003]     Driven rotary electrical valves, such as stepmotor valves, commonly are used to control the flow of a variety of fluids. Often the fluids that are controlled are under pressure such as, for example, in air-conditioning and refrigeration systems. A stepmotor valve typically includes a stepping motor having a threaded rotating shaft that is connected to a needle valve assembly. The needle valve assembly rotationally and axially moves into and out of physical engagement with a fixed orifice seat. A separate electronic controller sends a series of electronic pulses to a stator of the stepping motor in a manner known in the art, thereby causing rotor-valve assembly to rotate so as to vary the valve opening.  
         [0004]     The stepmotor valve of this invention is a removable “dry stator” type. The phrase “dry stator” indicates that the stator electrical windings are not inside the pressure vessel (e.g., not in the refrigerant environment, for instance) in which the rotor-valve assembly is mounted. These types of “dry stator” stepmotor valves include a stator valve assembly that can be removed from the rotor-valve assembly without opening the pressurized valve.  
         [0005]     Stepmotor valves are used in a wide range of environmental temperatures, pressures, and humidity levels including very wet environments that undergo continuous cycles of freezing and thawing. Existing stepmotor valves have little or no protection from the damaging effects of moisture and the distorting effects of freeze/thaw cycling.  
         [0006]     In prior art valves that are exposed to wet and/or freezing environments, moisture enters the stator housing through one or more openings in the stator housing, through the open end of the stator cavity, or through both. This moisture causes the eventual failure of the valve due to the corrosion and/or deformation of valve components. Specifically, the stator teeth that encircle stator windings typically are comprised of magnetic iron having a minimal thickness of protective plating. Moisture, over time, causes corrosion of the stator teeth. This corrosion allows moisture to penetrate motor windings causing an electrical malfunction of the motor. The expansion effects of freezing water, for example, can also cause stress cracks in the stator, thus allowing additional moisture penetration into the stator windings. The expansion effects of freezing water may also cause the permanent deformation of the rotor housing, thus preventing proper rotation of the rotor.  
         [0007]     The patent literature includes a large number of electrically rotary driven valve assemblies and stepmotor valves including: U.S. Pat. No. 4,574,686 to Budzich; U.S. Pat. No. 4,650,156 to Kawahira; U.S. Pat. No. 5,087,686 to Ishibashi et al.; U.S. Publication No. 2002/0189693 to Berto; Japanese Abstract No. 08321823 to Komiya et al.; and Japanese Abstract 2002081559 to Nomura et al. However, none of the prior art structures appear to utilize and/or suggest the unique configurations set forth herein.  
       SUMMARY OF THE INVENTION  
       [0008]     The present invention improves upon existing stepmotor valves by providing a waterproof seal between the stator assembly and the rotor-valve assembly. Additionally, the present invention provides a completely enclosed, non-perforated, dome-topped stator housing. The waterproof designs and structures provided by the differing sealing arrangements of the present invention prevent damaging corrosion and ice build-up between the stator assembly and rotor case or housing of the rotor-valve assembly by preventing moisture intrusion.  
         [0009]     Specifically, in one embodiment, the present invention relates to an electric motor driven valve assembly comprising a stator assembly having a stator housing in which a stator of the electric motor is located. The stator housing defines an internal cavity. A portion of the stator housing defines an open end of the internal cavity. The stator housing completely closes a remainder of the internal cavity. A rotor-valve assembly includes a rotor housing that is configured to be inserted through the open end of the internal cavity and received in the internal cavity of the stator housing. A sealing arrangement is interposed between the portion of the stator housing defining the open end of the internal cavity and the rotor housing for preventing an intrusion of moisture into the stator housing.  
         [0010]     In one version thereof the valve assembly is operated by a stepping motor. In another version, the stator housing and the rotor housing include associated locking members. The locking member of the rotor housing includes a locating plate ring portion.  
         [0011]     In a further embodiment of the present invention, an electrically rotatable stepmotor valve assembly comprises in combination an annular stator electrical winding assembly including a closed, continuous dome portion on one end thereof and a separate rotor-valve assembly. The stator assembly is removably mounted on the rotor-valve assembly. The stator assembly includes a housing and, starting at an open end thereof, an internal generally cylindrical cavity extending into the dome portion. The cavity has an internal peripheral surface of a first predetermined diameter. The rotor-valve assembly includes a generally cylindrical rotor housing having an external peripheral surface of a second predetermined diameter slightly smaller than the first predetermined diameter so as to permit slip fit assembly of the stator assembly over a cylindrical portion of the rotor-valve assembly so that the stator assembly surrounds a rotor portion of the rotor-valve assembly. Associated locking members on the stator and the rotor-valve assemblies permit rotary interlocking thereof upon the slip fit assembly. A sealing arrangement, in the vicinity of the open end of the stator assembly, peripherally seals the stator assembly relative to a radially adjoining peripheral portion of the rotor housing.  
         [0012]     The previously-described advantages and features, as well as other advantages and features, will become readily apparent from the detailed description of the preferred embodiments that follow.  
         [0013]     The present invention improves upon existing stepmotor valve assemblies by providing a waterproof seal between the stator assembly and the rotor-valve assembly as well as providing a completely enclosed, non-perforated, dome-topped stator housing. The waterproof designs and structures provided via the use of the differing sealing arrangements of the present invention prevent damaging corrosion and ice build-up between the stator assembly and rotor housing of the rotor-valve assembly by preventing moisture intrusion. 
     
    
     DESCRIPTION OF THE DRAWINGS  
       [0014]      FIG. 1  is a partially exploded sectional view of one embodiment of an electric motor driven valve assembly constructed in accordance with the present invention;  
         [0015]      FIG. 2  is a view similar to that of  FIG. 1 , but showing the valve assembly in an assembled condition;  
         [0016]      FIG. 2A  is an enlarged view of a portion of  FIG. 2 ;  
         [0017]      FIG. 3  is an elevation view of a rotor housing constructed in accordance with the present invention;  
         [0018]      FIG. 4  is a bottom view of the rotor housing of  FIG. 3 , looking in the direction of arrows  4 - 4  of  FIG. 3 ;  
         [0019]      FIG. 5  is an elevation view of a stator housing constructed in accordance with the present invention;  
         [0020]      FIG. 6  is a bottom view of the stator housing of  FIG. 5 , looking in the direction of arrows  6 - 6  of  FIG. 5 ; and  
         [0021]      FIGS. 7-12  are views similar to that of  FIG. 2A  successively showing a plurality of alternative sealing arrangements in accordance with the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0022]     Referring now to the drawings, illustrated in  FIG. 1  is a partially exploded, sectional view of one embodiment an electric motor driven valve assembly, generally indicated at  20 , of the present invention. The electric motor driven valve assembly  20  includes a stator assembly  22 , a rotor-valve assembly  24 , an annular ring member, such as washer  26 , and a sealing member, such as an O-ring  28 .  
         [0023]     The stator assembly  22  includes an asymmetrical housing  30  having a first, or large, inside diameter portion  32 . The first inside diameter portion  32  receives an annular stator portion  34  of an electric motor. The stator portion  34  includes upper and lower ring-shaped surfaces  36  and  38  as well as outer and inner cylindrical surfaces  40  and  42 . The housing  30  also includes an axially outwardly extending dome portion  50  having a second, or smaller, inside diameter portion  48 . A cylindrical wall portion  51  of the dome portion  50  has essentially the same inner diametrical extent  46  as the inner cylindrical surface  42  of the stator portion  34 . The stator inner cylindrical portion  42  and the cylindrical wall portion  51  of the dome portion  50  of the housing  30  collectively define an internal cavity  52  of the housing.  
         [0024]     As best seen in  FIGS. 1, 5  and  6 , the housing  30  includes, adjacent its annular bottom wall  54 , a pair of diametrically opposed, inwardly-directed projections  56 . The inwardly-directed projections are spaced slightly away from the annular bottom wall  54 . In addition, as best seen in  FIG. 6 , bottom wall  54  includes peripherally spaced, dimpled recesses  58 . As best shown in  FIG. 2A , the bottom wall  54  terminates at an end surface  68 . The end surface  68  is generally cylindrical and extends congruently with the inner cylindrical surface  42  of the stator portion  34 . A stator groove  70  extends into the end surface  68  adjacent a lowermost surface of the bottom wall  54 .  
         [0025]     The stator assembly  22  also includes a peripheral receptacle portion  60  for receiving a wire lead  62 . The wire lead  62  is operatively connected with stator windings  64 .  FIG. 1  also illustrates stator teeth  66  at inner cylindrical surface  42  of the stator portion  34 .  
         [0026]     With reference to  FIG. 1 , the rotor-valve assembly  24  includes a valve assembly portion  74 , such as a needle valve assembly. The valve assembly portion  74  includes a threaded rotatable shaft  76  that is operatively connected to an axially moveable valve portion  80 . Valve portion  80  is moveable axially into and out of physical contact and engagement with a fixed orifice seat  82  that controls the fluid flow between a fluid inlet pipe  84  and a fluid outlet pipe  86 .  
         [0027]     Attached to a flange  90  of needle valve body  88  is a lower end portion  94  of a generally cylindrical rotor housing  92 . The rotor housing  92  has a cylindrical outer surface  98  having a diametrical outer extent  96 . The cylindrical outer surface  98  is closed at its upper end by circular end portion  100 . An annular, radially outwardly extending bead  102  is formed in the housing  92  between a lower portion  92   b  and an upper portion  92   a.  Physically located within rotor housing  92  is a rotor portion  118  of an electric motor. The rotor portion  118  of the electric motor is rotationally coupled with valve assembly portion  74  in a manner well known in the art.  
         [0028]     A locating plate  104  having axial, peripherally spaced leg portions  106  and a radially extending ring portion  108  is permanently affixed, such as by spot welding, to housing portion  92   a  at a location in which the leg portions  106  abut the bead  102 . Ring portion  108  includes diametrically opposed cut-outs  110 , best seen in  FIG. 4 . As shown in  FIGS. 3 and 4 , ring portion  108  may also include two outwardly-directed spring-like, curved fingers  112 , each having an outwardly-directed dimple  114 .  
         [0029]     Advancing now to  FIGS. 2 and 2 A, the former illustrates valve assembly  20  in the assembled condition, i.e., when rotor-valve assembly  24  is received in the stator cavity  52  and is secured relative to the stator assembly  22 . Specifically, the rotor-valve assembly  24  is received in the stator cavity  52  of the stator assembly  22  through an open end. The open end of the stator cavity  52  is the only opening into the stator cavity as the remainder of the stator cavity is closed by the stator housing  30 . The rotor-valve assembly  24  is received in the stator assembly  22  in a slip-fit manner that leaves an annular air gap  120  ( FIG. 2A ) between stator assembly and rotor-valve assembly.  
         [0030]     As best visualized by viewing  FIGS. 4 and 6 , which illustrate bottom views of rotor housing  92  and stator housing  30 , respectively, during the assembly of stator assembly  22  and the rotor-valve assembly  24 , projections  56  pass through the cut-outs  110  of the ring portion  108  of the locating plate  104 . This occurs when axes  72  and  116  of  FIGS. 6 and 4 , respectively, are collinear. The stator housing  30  may be moved relative to the rotor housing  92  until the bottom wall  54  of the stator housing engages dimples  114  of locating plate fingers  112 . The stator housing  30  is then rotated relative to the rotor housing  92  so as to move locating plate cut-outs  110  out of alignment with projections  56 , thereby capturing locating plate ring portion  108  between the projections  56  and the bottom wall  54  of the stator housing  30 . When the locating plate ring portion  108  is secured between the projections  56  and the bottom wall  54  of the stator housing  30 , dimples  114  mate with recesses  58  and thus, lock the stator assembly  22  relative to the rotor-valve assembly  24 . The locking force between the dimples  114  and recesses  58  is determined by the spring force exerted by spring fingers  112  and generally is set to be readily overcome by a human operator. Once disengagement is desired, stator assembly  22  is rotated until locating plate cut-outs  110  again are aligned with projections  56 . The stator assembly  22  is then moved axially away from the rotor-valve assembly  24 . It should be understood that locating plate  104  together with projections  56  form associated locking members that permit the noted interlocking of stator assembly  22  with rotor-valve assembly  24 .  
         [0031]     The preferred embodiment of the present invention ( FIGS. 1 and 2 ) includes a stator assembly  22  that, at its upper end, is enclosed, by the stator housing  30 , including dome portion  50  and, at its lower end, is sealed to rotor housing  92  of the rotor-valve assembly  24 . The sealing arrangement  128  ( FIG. 2A ) between the stator assembly  22  and the rotor-valve assembly  24  includes retaining washer  26  and sealing member  28 . As shown in  FIG. 2A , when the rotor-valve assembly  24  and stator assembly  22  are secured together, in the manner already described, the washer  26  is supported on an upper surface of locating plate ring portion  108 . The washer  26  serves to retain sealing member  28  in stator groove  70  and in a position interposed between and engaging both the stator housing  30  and the rotor housing  92  thereby closing air gap  120  so as to prevent moisture intrusion.  
         [0032]     Additional, differing seal geometries, such as those set forth in  FIGS. 7-12 , will be discussed in more detail hereinafter. It should be understood that a unique, common feature of all of the structures and designs of  FIGS. 7-12  includes a supplemental seal  28  that is provided between rotor housing  92  and stator assembly  22 . The structures and designs of  FIGS. 7-12  also include a non-perforated, dome-topped stator assembly  22 . When discussing  FIGS. 7-12 , structures or features that have previously been described are referred to using the same reference numbers as used with reference to  FIGS. 1-6 .  
         [0033]     Turning first to  FIG. 7 , the design and structure of this sealing arrangement  130  does not require the use of washer  26  in order to retain sealing member  28 . Locating plate ring portion  108  is sufficient to retain sealing member  28  in its sealing position within stator groove  70 .  
         [0034]     The  FIG. 8  design and structure illustrate a sealing arrangement  132  utilizing a stepped annular retainer  134  that is affixed to the bottom wall  54  of stator housing  30  for retaining the sealing member  28  in the stator groove  70 . This embodiment is similar to sealing arrangement  128  ( FIGS. 1, 2  and  2 A), except that the shape of stepped retainer  134  is such that it may be fitted closely, such as via press fitting for example, to the stator housing  30 .  
         [0035]     The  FIG. 9  design and structure illustrate a sealing arrangement  138 , similar to embodiment  132  of  FIG. 8 , except that an annular retainer  140  is closely fitted, such as via press fitting for example, to rotor housing  92  so as to constrain sealing member  28 .  
         [0036]     Turning now to  FIG. 10 , the design and structure of this sealing arrangement  142  does not require a loose washer  26 , but instead utilizes a specialized geometry of rotor housing  92 , in the form of an intermediate step  93  in rotor housing, to retain sealing member  28 .  
         [0037]      FIG. 11  illustrates a design and structure of a sealing arrangement  144  in which sealing member  28  maintains sealing contact with stator bottom wall  54  but seals against an intermediate cylindrical component  146  that is fitted closely, such as via press fitting for example, to rotor case  92 . In this embodiment, it is necessary to attain a good seal between closely fitted intermediate component  146  and rotor housing  92 .  
         [0038]     Finally, the  FIG. 12  design and structure illustrate a sealing arrangement  148  that is similar to embodiment  144  of  FIG. 11 , except that a closely fitted, such as via press fitting for example, intermediate stepped component  150  is affixed to stator housing bottom wall  54  in the stator groove  70 .  
         [0039]     The preferred cross sectional geometry of sealing member  28 , such as an O-ring for example, is circular so as to permit contact on a minimum of one surface of rotor housing  92  or closely fitted intermediate cylindrical component  146  and a minimum of one surface on stator assembly  24  or closely fitted intermediate stepped cylindrical component  150 . There is also a wide variety of other acceptable cross sectional shapes, e.g., square, rectangular, triangular, oval, “X”, ribbed, etc., which are commonly used for sealing cylindrical surfaces. The preferred cross sectional geometry of washer  26  is rectangular, but other configurations that will retain sealing member  28  so as to facilitate its contact between rotor housing  92  and stator bottom wall  54  or intermediate components  146  or  150 , can provide acceptable functions.  
         [0040]     The preferred material for stator housing bottom wall  54  is plastic, including but not limited to: nylon, polyphenylene sulfide, polystyrene, and modified polypropylene oxide. The stator bottom wall  54  can also take the form of an adjacent closely fitted intermediate stepped cylindrical component  150 , as shown in  FIG. 12 . The preferred material for rotor housing  92  is non-magnetic stainless steel. Although stainless steel is not mandatory, it is typically utilized in order to maintain the pressure tight vessel that is necessary to contain the pressurized fluid that flows through valve assembly portion  74 . Alternate corrosion resistant materials, or materials with corrosion resistant coatings, can be used as long as they satisfy the various functional requirements of electrically driven valve assembly  20 . e.g., burst strength, compatibility, magnetic properties, etc. The rotor sealing surface, instead of residing on rotor housing outer peripheral surface  98 , can also be located on adjacent, closely fitted intermediate cylindrical component  146  as illustrated in  FIG. 11 . The material for sealing member  28  should be an elastomer resistant to water, with a silicone based elastomer being the preferred material. Alternate soft or semi-rigid elastomeric materials can also be used to provide an adequate seal. Hybrids of rigid or semi-rigid materials can also be used, e.g., coated washers, Stat-o-Seals®, etc. The preferred material for washer  26  is stainless steel due to its rigidity and corrosion resistance. Other rigid or semi-rigid materials that have sufficient corrosion resistance can also be used. The purpose of washer  26  is to provide support to resist extrusion of seal member  28  while retaining same in its position within stator groove  70  so that seal member  28  can seal against stator bottom wall  54  as well as rotor housing surface  98 . Washer  26  can also be used with configurations utilizing closely fitted components  146  and  150  as an alternate sealing surface as shown in  FIGS. 11 and 12 , respectively. Locating plate  104 , which can alternatively be used to solely retain sealing member  28 , is preferably stainless steel or of an alternate material, for reasons similar those already explained for washer  26 .  
         [0041]     It is deemed that one of ordinary skill in the art will readily recognize the several embodiments of the present invention fill remaining needs in this art and will be able to affect various changes, substitutions of equivalents and various other aspects of the invention as described herein. Thus, it is intended that the protection granted hereon be limited only by the scope of the appended claims and their equivalents