Abstract:
A modular selector switch operator includes a housing and a cylinder rotationally mounted in the housing. The cylinder has a radially extending follower and a circumferential cam track. A knob extends forwardly of the housing and is operatively connected to the cylinder for rotating the cylinder. A pusher is received in the housing and has a follower pin riding in the cam track to convert rotational movement of the cylinder to linear movement of the pusher for actuating an electrical switch, in use. An indexing cam ring is concentrically mounted to the cylinder in the housing in one of two orientations with the cylinder follower engaging the cam ring. A first orientation provides a maintained actuation position relative to a neutral position. A second orientation provides a momentary actuation position relative to the neutral position.

Description:
FIELD OF THE INVENTION 
     This invention relates to electro-mechanical switches and, more particularly, to a modular, water resistant selector switch operator. 
     BACKGROUND OF THE INVENTION 
     A selector switch is commonly used as a manually operated controller for industrial electric motor control circuits. A selector switch is typically mounted in a front panel of a control enclosure. Selector switches are used in applications where rotary knob actuation of the control circuit is desired, as opposed to push button or knife switches, for example. A knob operated selector switch has a rotatable knob that actuates an electrical switch to open and close electrical circuits. 
     Existing NEMA (National Electrical Manufacturers Association) industry 22 mm selector switches perform basic selector switch functions in various configurations, such as two or three actuation positions and momentary or maintained contact actuation. These switches have not generally been constructed for environmental water entry resistance required by both NEMA  4  water spray tests and NEMA  6  water submersion tests. Also, prior such switches utilize different mechanical components for the six most common switch configurations requiring additional investments in tooling and inventory for manufacturing. 
     The present invention is intended to overcome the problems discussed above, in a novel and simple manner. 
     SUMMARY OF THE INVENTION 
     In accordance with the invention there is provided a modular selector switch design, reducing the number of unique switch components for different switch configurations. 
     Broadly, there is disclosed herein a modular selector switch operator including a housing and a cylinder rotationally mounted in the housing. The cylinder has a radially extending follower and a circumferential cam track. A knob extends forwardly of the housing and is operatively connected to the cylinder for rotating the cylinder. A pusher is received in the housing and has a follower pin riding in the cam track to convert rotational movement of the cylinder to linear movement of the pusher for actuating an electrical switch, in use. An indexing cam ring is concentrically mounted to the cylinder in the housing in one of two orientations with the cylinder follower engaging the cam ring. A first orientation provides a maintained actuation position relative to a neutral position. A second orientation provides a momentary actuation position relative to the neutral position. 
     It is a feature of the invention that the cam ring has plural ramped surfaces for riding on the follower, the ramped surfaces that ride on the follower in the first orientation including detents for locking the cylinder to the cam ring in the maintained actuation position. A spring biases the cam ring against the follower. 
     It is another feature of the invention that the selector switch comprises a three position switch and the housing limits movement of the cylinder to approximately 100 degree rotation or the selector switch comprises a two position switch and the housing limits movement of the cylinder to approximately 50 degree rotation. 
     It is a further feature of the invention that the cam ring includes first and second axial end surfaces each having plural ramped surfaces. The ramped surfaces at the first axial end have detents. The first axial end surface engages the follower in the first orientation and the second axial end surface engages the follower in the second orientation. 
     It is still another feature of the invention that the cam ring is rotationally constrained in the housing. 
     It is an additional feature of the invention that the cam ring includes first and second axial end surfaces each having opposite pairs of intersecting ramped surfaces. One of each of the intersecting ramped surfaces has a detent. The follower is positioned proximate the intersection of the ramped surfaces in the neutral position and the ramped surface having the detent is clockwise from the intersection in the first orientation and counterclockwise from the intersection in the second orientation. 
     There is disclosed in accordance with another aspect of the invention a selector switch operator including a one-piece tubular barrel housing and a cylinder rotationally mounted in the housing. The cylinder has a radially extending follower and a circumferential cam track. A knob extends forwardly of the housing and is operatively connected to the cylinder for rotating the cylinder. A pusher is received in the housing and has a follower pin riding in the cam track to convert rotational movement of the cylinder to linear movement of the pusher for actuating an electrical switch, in use. A ring gasket surrounds the knob and is received in the barrel housing. The ring gasket includes a wiper seal engaging an inner wall of the housing to prevent water entry into the housing. 
     It is a feature of the invention that the ring gasket is U-shaped in cross section. The gasket includes an inner cylindrical wall and end wall engaging the knob and an outer cylindrical wall engaging the inner wall of the housing. The ring gasket is formed of rubber. 
     It is another feature of the invention to provide a panel gasket surrounding an outer wall of the housing for sealing the housing in an enclosure panel, in use. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a selector switch operator in accordance with the invention; 
     FIG. 2 is a front view of the selector switch operator of FIG. 1 adapted for a two position operation; 
     FIG. 3 is a front view of the selector switch operator of FIG. 1 adapted for a three position operation; 
     FIG. 4 is a rear perspective view of the selector switch operator of FIG. 1; 
     FIG. 5 is an exploded perspective view of the selector switch operator of FIG. 3; 
     FIG. 6 is a side view of a contact block used with the selector switch operator of FIG. 1; 
     FIGS. 7-12 illustrate cylinder and indexing cam ring combinations used with the selector switch operator of FIG. 1; and 
     FIG. 13 is a sectional view illustrating gasket operation for the selector switch of FIG.  1   
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring initially to FIG. 1 a selector switch operator  20  in accordance with the invention is illustrated. The selector switch operator  20  is for a NEMA 22 mm selector switch that meets the ratings of the NEMA  4  water spray test and the NEMA  6  water submersion test. However, the features of the invention are not limited strictly to a 22 mm selector switch. Also, the selector switch operator  20  has a reduced number of unique components required for manufacture of all six standard NEMA industry two and three position selector switch actuation configurations, enhancing manufacturing economies of scale. FIG. 2 illustrates the selector switch operator  20  configured for two position operation, while FIG. 3 illustrates the selector switch operator  20  configured for three position operation. 
     Referring also to FIGS. 4 and 5, the selector switch operator  20  includes a one-piece tubular barrel housing  22 . A rotary knob  24 , used for switch actuation, extends forwardly of the housing  22  and is retained by a front ring  26  screwed onto the housing  22  at a threaded outer front end wall  28 , see also FIG.  13 . The knob  24  is seated on a cap  30  that couples rotation of the knob  24  to a cylinder  32  internal to the housing  22 . Particularly, the knob  24  includes an inner notched cylindrical surface  34 . The cap  30  extends into the knob  24  and has an outer radial tooth  36  engaging the notched surface  34  to be rotational therewith. 
     The cylinder  32  is telescopically received in the cap  30  and has front end notches  38  receiving inner radial teeth  40  of the cap  30  to be rotational therewith. Thus rotation of the knob  24  causes rotation of the cylinder  32  in the housing  22 . Two pointed cam followers  42 , one of which is shown, are on opposite sides of the cylinder  32 . A circumferential cam track  44  extends around the cylinder  32  at a rear end  46 . The followers  42  support and slide radially over an indexing cam ring  48  externally concentric to the cylinder  32  in the housing  22 . The cam ring  48  is rotationally constrained by tabs  50  received in axially extending grooves, not shown, on an inner wall of the housing  22 . A helical compression spring  52 , between the cap  30  and the cam ring  48 , biases the cam ring  48  against the cylinder followers  42 . 
     Rotation of the knob  24 , and thus cylinder  32 , causes the followers  42  to move the cam ring  48  from a rest or neutral position, described below, axially toward the knob  24  compressing the spring  52 . The reaction load of the compressed spring  52  against the cam ring  48  is translated through the cylinder followers  42  into a return torque that rotates the cylinder  32  and the knob  24  back to the neutral position. Detents or notches, discussed below, on the cam ring  48  can engage the followers  42  and lock the cam ring  48  to the cylinder  32  providing maintained actuation of the switch operator  20 . Conversely, the lack of a notch on the cam ring  48  permits the spring-biased cam ring  48  and follower action to spring-return to the neutral position, providing momentary action of the switch operator. 
     For the two position switch operator configuration shown in FIG. 2, the neutral position is twenty-five degrees counter-clockwise from “12 O&#39;clock”. The actuation position is to the right, fifty degrees clockwise. For the three position switch operator configuration shown in FIG. 3, the neutral position is centered at “12 O&#39;clock”. The left actuation position is fifty degrees counter-clockwise. The right actuation position is fifty degrees clockwise. The six following switch actuation configurations are possible: 
     two positions, maintained right; 
     two positions, momentary right; 
     three positions, maintained left and right; 
     three positions, momentary left and right; 
     three positions, maintained left, momentary right; and 
     three positions, momentary left, maintained right. 
     In accordance with the invention, one version of the cam ring  48  is used for the first four configurations, shown in FIGS. 7-10, while a second version cam ring  48 ′ is used for the last two configurations, shown in FIG. 11 and 12. 
     A set of axial grooves  54 , see FIG. 5, one of which is shown, in the housing  22  slidably receive a pair of pushers  56 . The grooves  54  radially constrain the pushers  56 . Each pusher  56  includes a radially inwardly extending follower pin  58 . Each follower pin  58  is received in and engages the cylinder cam tracks  44 . Cylinder rotation extends and retracts the pushers  56  axially from the housing  22 , as illustrated by the two positions in FIG.  4 . The sequence of pusher action is determined be the cam track pattern. The one cylinder version  32  is used for three position switches, see FIGS. 9-12. Another cylinder version  32 ′ is used for two position switches, see FIGS. 7 and 8. The cam track  44  is adapted to retract both pushers  56  in the neutral position, extend one pusher  56  in the left position and extend the other pusher  56  in the right position. A portion of the cam track  44  receives a tab in the housing  22  to axially constrain the cylinder in the housing. Similarly, the cylinder  32 ′ includes a cam track  44 ′ adapted to retract both pushers  56  in the neutral position and extend both pushers  56  in the right position. A portion of the cam track  44 ′ receives a tab in the housing  22  to axially constrain the cylinder in the housing. 
     A contact block  60 , see FIG. 6, having an internal electrical switch, is mounted on base feet  62  of the housing  22  using snap-fit toggle linkages  64  integral to the contact block  60 , as is known. Actuation of the knob  24 , which is coupled to the cylinder  32 , extends the pushers  56  from the housing  22  depressing a contact block plunger  66  causing the electrical switch to switch electrical states. The housing  22  can support up to three contact blocks  60  for separate or simultaneous actuation by the two pushers  56 . 
     The cam ring  48  includes first and second axial end surfaces  70  and  72 , see FIGS.7 and 8. The first axial end surface  70  includes opposite pairs of intersecting ramped surfaces  74  and  76 . Similarly, the second axial end surface  72  includes opposite pairs of intersecting ramped surfaces  78  and  80 . Each of the intersecting ramped surfaces  78  and  80  has detents  82 . The cam ring  48  can be positioned in a first orientation, as shown in FIGS. 7 and 9 to provide maintained actuation or in a second orientation, as shown in FIGS. 8 and 10 to provide momentary actuation. In the first orientation the cam followers  42  engage the second axial end surface  72  having the detents  82 . In the second orientation the cam followers  42  engage the first axial end surface  70  having no detents. Thus, turning the cam ring  48  upside down 180 degrees and rotating 90 degrees converts the selector switch operator  20  from momentary operation to maintained operation, and vice-versa. 
     The cam ring  48 ′ includes first and second axial end surfaces  70 ′ and  72 ′, see FIGS. 11 and 12. The first axial end surface  70 ′ includes opposite pairs of intersecting ramped surfaces  74 ′ and  76 ′. Similarly, the second axial end surface  72 ′ includes opposite pairs of intersecting ramped surfaces  78 ′ and  80 ′. Each of the intersecting ramped surfaces  74 ′ and  80 ′ have detents  82 ′. The cam ring  48 ′ can be positioned in a first orientation, as shown in FIG. 11 to provide maintained actuation to the left or in a second orientation, as shown in FIG. 12 to provide maintained actuation to the right. Thus, turning the cam ring  48 ′ upside down 180 degrees and rotating 90 degrees converts the selector switch operator  20  from left maintained operation to right maintained operation, and vice-versa. The selector switch operator  20  is sealed against internal water entry by a ring gasket  86  incorporating a wiper seal. The gasket  86  is U-shaped in cross section, see FIG. 13, and includes an inner cylindrical wall  88  and end wall  90  engaging the knob  24  and an outer cylindrical wall  92  engaging an inner wall  94  of the housing  22 . The outer cylindrical wall  92  acts as a wiper seal to prevent water entry into the housing  22 . The ring gasket  86  is formed of a neoprene rubber. 
     A panel gasket  96 , having an L-shape in cross section, surrounds an outer wall  98  of the housing  22 , at a shoulder  100 , for sealing the housing  22  in an enclosure panel, in use. The gasket  96  may also be of neoprene rubber. 
     The use of common interchangeable components for multiple assembly configurations with different functional modes may be applicable to other mechanisms using rotary actuated cams for indexing and torsion driven biasing. 
     Thus, in accordance with the invention there is provided a selector switch operator having improved water resistance. The operator also has only two internal components varied to assemble six standard switch actuation configurations, and only two versions of each such component are required for all configurations.