Abstract:
An exemplary embodiment of a pneumatic actuator assembly includes a hollow body member, and a transverse nipple member including a flange portion, and a hollow passageway leading to a hollow nipple portion. A bellows member is positioned in the body member and is configured to receive the flange portion of the nipple member at an open end. A button member disposed at the closed end of the bellows member and arranged to slide within a range of movement within the body member to compress the bellows and actuate the assembly. The nipple portion of the nipple member is arranged transversely with respect to the longitudinal axis of the body member and configured for connection to a hollow tubing end.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 61/291,671 filed Dec. 31, 2009, the entire contents of which are hereby incorporated by reference. 
     
    
     BACKGROUND 
       [0002]    Air or pneumatic switch systems are typically used in environments subject to wet conditions, to control electrical equipment without exposing the user to electrical shock hazards. The systems employ a pneumatic actuator, connected to a receiver device by a sealed air conduit. The user can press a button on the actuator, which compresses the air in the sealed conduit. The compression is sensed by the receiver device, and the received device performs electrical switching in response to the sensing. 
         [0003]    Problems can be encountered in installing the actuators in surfaces with limited clearance space. For example, the air switches are sometimes used in bathing installations such as whirlpool baths or spas, and preferred locations for installation of the actuator may be on surfaces of the tub of the bathing installation. Clearance space behind the exposed surface is typically limited. Conventional actuators employ a nipple to connect to tubing which exits 180 degrees from the top, i.e. aligned with the center axis of the actuator. The tubing then protrudes a distance from the bottom of the actuator. This arrangement provides no protection for the exposed nipple, which can be impacted and broken off. Moreover, the tubing can be knocked off in installation, e.g. the tubing can get caught on a stud or board when being dropped into place, and pulled away from the nipple. This is particularly a problem when the actuator is pre-installed on a bathing installation tub at the factory, and the tub is later installed on-site. While the operating button of the actuator is visible from the exposed surface of the tub, the back-side of the actuator with attached tubing will not be readily visible to the installer. The actuator can readily be damaged by striking a support such as a stud or board, particularly with the weight of the tub adding to the force applied during installation. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0004]    Features and advantages of the disclosure will readily be appreciated by persons skilled in the art from the following detailed description when read in conjunction with the drawing wherein: 
           [0005]      FIG. 1  is a diagrammatic isometric view of an exemplary embodiment of a pneumatic switch system for controlling an electrically power device or system, including a pneumatic actuator assembly. 
           [0006]      FIG. 2A  is an isometric bottom view of the actuator assembly of the system of  FIG. 1 . 
           [0007]      FIG. 2B  is an isometric bottom view similar to  FIG. 2A , but with a tube attached to the output port of the actuator assembly for connection to a receiver switch. 
           [0008]      FIG. 3  is a top view of the actuator assembly of  FIG. 1 . 
           [0009]      FIG. 4  is a cross-sectional view of the actuator assembly, taken through line  4 - 4  of  FIG. 3 . 
           [0010]      FIG. 5  is a cross-sectional view of the actuator assembly, taken through line  5 - 5  of  FIG. 3 . 
           [0011]      FIG. 6  is a bottom view of the actuator assembly of  FIG. 2B . 
           [0012]      FIG. 7  is an exploded view of the actuator assembly of  FIG. 1 . 
           [0013]      FIGS. 8A and 8B  are respective top and bottom isometric views of an alternate embodiment of a pneumatic actuator assembly.  FIG. 8C  is a side view of the actuator assembly of  FIGS. 8A and 8B . 
           [0014]      FIG. 9  is a top view of the actuator assembly of  FIGS. 8A-8C . 
           [0015]      FIG. 10  is a cross-sectional view taken through line  10 - 10  of  FIG. 9 . 
           [0016]      FIG. 11  is an exploded view of the actuator assembly of  FIGS. 8A-8C . 
       
    
    
     DETAILED DESCRIPTION 
       [0017]    In the following detailed description and in the several figures of the drawing, like elements are identified with like reference numerals. The figures are not to scale, and relative feature sizes may be exaggerated for illustrative purposes. 
         [0018]    An exemplary embodiment of a pneumatic actuator assembly  50  is depicted in  FIG. 1 . The actuator assembly is connected to a receiver switch  30  by a flexible hollow tube  40  to provide a sealed air conduit between the actuator and the receiver switch. The receiver switch  30  is conventional, and there are different receiver switches readily available in the marketplace. The receiver switch  30  is connected to an electrical device or system  20  by an electrical line or cabling  32 , and may be used to control operation of the device or system  20 , e.g. by turning the device on or off, or to otherwise provide a control signal to the device or system  20 . For a bathing installation application, the device or system  20  may be, for example, a pump, blower, light or other device associated with the bathing installation. For a kitchen application, the device or system  20  may be a garbage disposal, for example. The actuator assembly  50  may be employed in other applications to control or operate other devices as well. 
         [0019]    An exemplary embodiment of the actuator assembly  50  is illustrated in further detail in  FIGS. 2-7 . The assembly includes a hollow body member  60  having a generally cylindrical outer configuration, with a flange  62  formed at one end, an intermediate threaded exterior portion  64 , and a skirt portion  66  extending from the threaded portion. A hole or opening  66 A is formed in the skirt portion, providing an entry portal through the skirt portion for insertion of the tube  40 . The body member  60  further includes a transverse bottom wall portion  68  formed across the interior of the body portion at a junction between the threaded portion and the skirt portion. The bottom wall portion  68 A has an opening formed therein to receive a 90 degree nipple member  70 . The opening  68 A is generally circular, with opposed windows  68 B and  68 C extending out from the periphery of the circle configuration, to facilitate assembly of the nipple member to the body member. 
         [0020]    In an exemplary embodiment, the body member  60  is a unitary injection-molded part, made from a plastic material such as ABS. 
         [0021]    The assembly  50  further comprises the 90 degree nipple member  70 , a bellows member  80 , a bias member  86  disposed inside the bellows to bias the bellows to an extended position, a cup-like button member  90  and an escutcheon  92 . A threaded nut  96  is provided to secure the body member in place after the body member has been inserted through an opening in a mounting wall or surface, with the flange portion  62  larger than the wall opening. 
         [0022]    In an exemplary embodiment, the bellows  80  is an inverted cup-like member with an interior volume, and may be fabricated of an elastomeric material, e.g. rubber, to allow the bellows to be compressed to reduce the size of the interior volume. As illustrated in  FIGS. 4 and 5 , for example, the exterior diameter of the bellows  80  is slightly smaller than the interior diameter of the body member  60 . The top closed wall portion  80 A of the bellows tapers to a generally flat end portion  80 B, to define a recess  80 C sized to receive an end of the bias member  86 , which is a spring in this embodiment. In other embodiments, the spring may be molded into the bellows, or omitted as a separate bias structure if the bellows is formed of a material with sufficient memory to restore to the extended position after being compressed by a button push. 
         [0023]    The open end of the bellows  80  is fabricated with a double flange portion  80 D. The flange portion is sized to allow the nipple member  70  to be inserted into the flange portion for assembly. The bellows in this embodiment is elastic, allowing the bottom lip of the flange portion to be manipulated open to insert the nipple member. The bellows, spring and nipple member can thus be assembled together to form a sub-assembly, for insertion into the body member  60 . 
         [0024]    The nipple member  70 , e.g. as shown in  FIGS. 4-6 , is a unitary member fabricated of injection-molded plastic, e.g. ABS. The nipple member defines an interior plenum region  74  in fluid communication with a passageway  74 A leading to a transverse, hollow, 90 degree nipple portion  72 . In this embodiment, the passageway  74 A has an axis  70 -A which is offset from the center axis  50 - 1  of the actuator assembly  50 . At the opposite end of the nipple member from the nipple  72 , a flange  76  is defined, and is sized for fitting into the channel  80 D 1  defined by the double flange portion  80 D of the bellows. When the flange  76  of the nipple is fitted into the corresponding flange portion of the bellows, a gas seal is formed between the periphery of the flange  76  and the bellows. The open interior volume of the bellows is then in communication with the plenum  74  of the nipple member  70 . 
         [0025]    The nipple member  70  further has opposed locking tabs or ears  75 A,  75 B ( FIG. 5 ) spaced from the flange portion  76  to form open channels regions  75 C,  75 D. The locking tabs and the open channel regions are sized in cooperation with corresponding dimensions of the bottom wall  68 , and the opening  68 A, and open windows  68 B,  68 C, to allow the assembly of the sub-assembly of the bellows-spring-nipple member to the body member  60 . Particularly, the sub-assembly can be inserted into the body member  60  at the flange end of the body member, with the nipple member oriented so that the locking tabs  75 A,  75 B are aligned with the open windows  68 B,  68 C of the opening  68 A in the bottom wall  68  of the body member in an insertion orientation. With the axis of the passageway  74 A offset from the center axis of the body member, the nipple  72  and the locking tabs  75 A,  75 B can be inserted through the opening  68 A until the bottom surfaces of the bellows  80  at the flange portion  80 D and shoulder region  77  of the nipple member contacts the bottom wall  68 . Then the sub-assembly is rotated 90 degrees relative to the body member in an assembly orientation, so that the locking tabs are brought into contact with the underside of the bottom wall and ramp regions  68 D of slightly increasing thickness, with the flange portions of the bellows being compressed against the bottom wall  68 , thereby locking the nipple member in place and providing a fluid seal. 
         [0026]    The skirt portion  66  of the body member in this embodiment is elongated, so that its distal end extends beyond the tip of the nipple member in the assembled orientation. The skirt portion provides a protective shield, preventing damage to the nipple, and the tube attached to the nipple. With the nipple member in the assembled orientation, the axis  72 -A of the nipple  72  will be substantially aligned with an opening  66 A formed in the skirt portion  66  of the body member  60 . The end of the tube  40  can be inserted through the opening  66 A and pushed onto the nipple  72  to provide a press-fit seal. To provide a stress relief clamp, the opening  66 A is defined by chamfering the wall of the skirt portion, so that the diameter of the opening at the exterior surface of the wall is slightly larger than the outer diameter of the tubing, and the diameter of the opening at the interior surface of the wall is slightly smaller than the outer diameter of the tubing. This forms “Chinese” fingers at the opening which allow the tube to be inserted into the opening to press onto the nipple, but then resist pulling the tube out away from the nipple and out the opening. 
         [0027]    With the sub-assembly of the nipple-bellows-bias member assembled to the body member  60 , the button member  90  may be inserted into the body member, until the distal edge of the button member contacts the bellows member, e.g. as shown in  FIG. 4 . The outer diameter of the button member is slightly smaller than the inner diameter of the body member at the flange end. In this embodiment, the diameter of the region  80 B of the bellows is smaller than the inner diameter of the button member, and is received within the open region within the button member. Thus, by pressing on the top  90 A of the button member, the user can apply pressure on the bellow to compress the bellows, thus compressing the air within the bellows and the plenum  74  of the nipple member  70 . To retain the button member within the body member, an escutcheon  92  is press-fit into the body member at the flange end. The button member has a somewhat reduced diameter at its upper end, to form a shoulder  90 B. When the escutcheon is press-fitted into the body member, the escutcheon distal end contacts the shoulder  90 B, fixing the upper end of travel of the button member within the body region. 
         [0028]    The actuator assembly  50  may be connected by the tubing  40  to the receiver  30 , as shown in  FIG. 1 , providing a closed air conduit between the bellows member and the receiver. The receiver typically includes a pressure sensitive transducer, responsive to the user pressing the button member  90  to compress the air volume within the bellows and increase the pressure in the closed conduit, to actuate an electrical switch in the receiver. The switch may then control operation of the device  20 , e.g. in the bathing installation example, a pump operating on line voltage, or a light operating on low voltage. 
         [0029]    The embodiment of the actuator assembly illustrated in  FIGS. 1-7  provides a number of advantages over conventional actuators, including the following: 
         [0030]    a. The actuator may have a shorter overall length due to the tube not exiting 180 degrees from the top of the button, thus permitting the actuator to be used in tighter spaces. 
         [0031]    b. The actuator does not have unprotected protruding tubing, to be knocked off in installation of a bathing installation tub. 
         [0032]    c. Built in strain relief is provided by the hole in the outer skirt portion or sheath (as the tubing is pushed through the hole to be installed on the right angle nipple, strain relief is formed). 
         [0033]    d. The sheath around the nipple protects against damage. 
         [0034]    e. A shorter length of tubing can be used to connect to the receiver, as the actuator can be positioned with the nipple oriented in the direction of the pump or device to which it is being connected (typically the received may be installed on the pump or device). 
         [0035]    An alternate embodiment of an actuator assembly  50 ′ is illustrated in  FIGS. 8A-11 . The alternate embodiment differs from the embodiment of  FIGS. 1-7  in several respects. The nipple member, bellows, bias member, nut button member and escutcheon elements are all similar to those described above regarding the assembly  50  ( FIGS. 1-7 ), and the same reference numbers refer to the corresponding parts. The body member  60 ′ of the alternate embodiment  50 ′ differs from the body member  60  in the following respects. 
         [0036]    The body member  60 ′ does not include the skirt or shield portion  66  of the body member  60 . The body member  60 ′ terminates at bottom wall  68 ′, with the right angle nipple region of the nipple member  70  protruding from the opening in the bottom wall  68 ′. This allows the actuator assembly  50 ′ to have a reduced overall length relative to the embodiment of  FIGS. 1-7 , although the protective skirt or shield is not provided in this embodiment. An optional feature which may be included in the body member  60 ′ is the protruding boss  67 , formed with an open loop  67 A opposite the terminal end of the right angle nipple  72 . The tubing  40  may be inserted through the open loop and passed around to the nipple to be fitted onto the nipple. The boss and open loop may then provide some strain relief to the tubing. 
         [0037]    Although the foregoing has been a description and illustration of specific embodiments of the invention, various modifications and changes thereto can be made by persons skilled in the art without departing from the scope and spirit of the invention.