Push-pull switch operator

Information

  • Patent Grant
  • 6268577
  • Patent Number
    6,268,577
  • Date Filed
    Thursday, December 16, 1999
    25 years ago
  • Date Issued
    Tuesday, July 31, 2001
    23 years ago
Abstract
A push-pull switch operator includes a housing. A rotary drive is rotationally mounted in the housing and has a circumferential cam track. An actuator is operatively coupled to the rotary drive for converting linear movement of the actuator to rotary movement of the rotary drive. A pusher is received in the housing and has a follower pin riding in the cam track to convert rotary movement of the cylinder to linear movement of the pusher. The pusher actuates an electrical switch. A cap is operatively coupled to the actuator for manually operating the actuator between in, middle and out positions to selectively operate the pusher.
Description




FIELD OF THE INVENTION




This invention relates to electromechanical switches and, more particularly, to a push-pull switch operator.




BACKGROUND OF THE INVENTION




A push-pull switch is commonly used as a manually operated controller for industrial electric motor control circuits. A push-pull switch is typically mounted in a front panel of a control enclosure. Push-pull switches are used in applications where push and pull actuation of the control circuit is desired, as opposed to single push button, rotary selector switch or knife switches, for example. A push-pull switch has a cap that actuates an electrical switch to open and close electrical circuits.




Prior push-pull switches used spring-loaded ball bearings to pop into side grooves. The cap was directly linked to a pushing part that actuated the electrical contact blocks. The ball bearings detented into side grooves, locating the position of the linkage to an in position, a middle position, or an out position.




Because of the direct linkage used in prior push-pull switches, switch contacts could move only about half of the distance normally travelled by a conventional push-button operator in moving from middle to in-positions, or middle to out-positions. This reduced the open air gap in the contact blocks, forcing a reduction in ampere rating for a standard contact block or the use of special early-make or late-break contact blocks. The use of a direct linkage also required that all contact blocks used with the push-pull switch operate simultaneously. This reduced the application options for individual push-pull switches. Also, spring-loaded ball bearings can be difficult to assemble.




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 a push-pull switch uses indirect contact actuation.




In accordance with one aspect of the invention there is disclosed a push-pull switch operator including a housing. A rotary drive is rotationally mounted in the housing and has a circumferential cam track. An actuator is operatively coupled to the rotary drive for converting linear movement of the actuator to rotary movement of the rotary drive. A pusher is received in the housing and has a follower pin riding in the cam track to convert rotary movement of the cylinder to linear movement of the pusher. The pusher actuates an electrical switch, in use. A cap is operatively coupled to the actuator for manually operating the actuator between in, middle and out positions to selectively operate the pusher.




It is a feature of the invention that the rotary drive comprises a two-piece assembly having a driver operatively coupled to the actuator whereby linear movement of the actuator is converted to rotary movement of the driver and a cam operatively coupled to the driver for rotation therewith and the cam track pattern is provided on the cam. A torsion spring biases the cam in the housing so that the actuator is normally in the middle position.




It is another feature of the invention that the actuator comprises a cylinder including a helical slot and the rotary drive is telescopically received in the cylinder and has a driver-arm received in the helical slot. The housing has a circumferential slot receiving the driver-arm to constrain linear movement of the rotary drive.




It is a further feature of the invention to provide a second pusher received in the housing and having a follower pin riding in the cam track to convert rotational movement of the cylinder to linear movement of the second pusher. The second pusher actuates a second electrical switch, in use. The cam track is configured to operate the two pushers in opposite directions. The cam track comprises oppositely-oriented helical tracks.




It is another feature of the invention that the driver-arm extends radially outwardly from a flexible arm. A spring in the rotary drive prevents inward deflection of the flexible arm.




It is yet another feature of the invention to provide an apron snap fit to the actuator and surrounding a front end of the housing. A ring gasket surrounds an outer wall at the front end of the housing and contacts the apron for sealing the housing. The ring gasket is formed of rubber and includes a wiper seal.




There is disclosed in accordance with another aspect of the invention a push pull switch operator including a housing. A drive assembly is movably mounted in the housing and has a cam track. A cap is operatively coupled to the drive assembly. The cap is manually, linearly actuable between in, middle and out positions. A pusher is received in the housing and has a follower pin riding in the cam track. The cam track is configured to convert linear movement of the cap in one direction to linear movement of the pusher in an opposite direction. The pusher actuates an electrical switch, in use.




Further features and advantages of the invention will be readily apparent from the specification and from the drawing.











BRIEF DESCRIPTION OF THE DRAWINGS





FIG. 1

is a partial sectional view, with parts removed for clarity, of a push-pull switch operator in accordance with the invention in a normal or middle position.





FIG. 2

is a view similar to that of

FIG. 1

illustrating the operator pushed to an in-actuated position;





FIG. 3

is a view similar to that of

FIG. 1

illustrating the operator pulled to an out-actuated position;





FIG. 4

is an exploded view of a drive assembly for the push-pull operator of

FIG. 1

;





FIGS. 5-12

comprise a series of views illustrating an assembly sequence for the push-pull switch operator of

FIG. 1

; and





FIG. 13

is a side view of a contact block used with the push-pull switch operator of FIG.


1


.











DETAILED DESCRIPTION OF THE INVENTION




Referring initially to

FIG. 1

, a push-pull switch operator


20


in accordance with the invention is illustrated. The push-pull switch operator


20


can operate separate contact blocks. In accordance with the invention, the contact blocks can be actuated in a direction opposite of the direction of the pulling actuation of the operator


20


, as described more specifically below.




The operator


20


includes a tubular barrel housing


22


. The housing


22


includes a barrel


84


and a front ring


86


. A drive assembly


24


, partially illustrated in

FIG. 1

, is movably mounted in the housing


22


. A mushroom cap


26


is operatively coupled to the drive assembly


24


. The cap


26


is manually, linearly actuable from a neutral or middle position, as shown in

FIG. 1

, and can be pushed to an “in” position illustrated in

FIG. 2

, and can be pulled to an “out” position shown in FIG.


3


. First and second pushers


28


and


30


are received in the housing


22


and are operatively coupled to the drive assembly


24


. The drive assembly


24


is configured, as described below, to convert linear movement of the cap


26


in one direction to linear actuation movement of the first pusher


28


in the same direction and linear actuation movement of the second pusher in an opposite direction. The pushers


28


and


30


actuate an electrical switch in separate contact blocks, such as a contact block


32


, see

FIG. 13

, as described below.




Referring to

FIG. 4

, the drive assembly


24


includes a two-piece rotary drive


34


and an actuator


36


. The rotary drive


34


includes a driver


38


and a cam


40


.




The actuator


36


comprises an outer cylindrical wall


42


having a radially inwardly directed front end shoulder


44


connecting a threaded collar


46


. An elongate groove


48


, one of which is shown, is provided on each of opposite sides of the cylindrical wall


42


. A helical slot


50


is provided on either side of the cylindrical wall


42


disposed between the grooves


48


. A pair of openings


52


, one of which is shown, are provided at the top of the cylindrical wall


42


proximate the shoulder


44


above each slot


50


.




The driver


3




8


comprises a cylindrical wall


54


having plural circumferentially spaced notches


56


at a rear end


58


. The cylindrical wall


54


has an outer diameter slightly less than an inner diameter of the actuator cylindrical wall


42


to be telescopically received therein. A pair of opposite driver arms


60


extend radially outwardly from the cylindrical wall


54


proximate a front end


62


. Each driver arm


60


includes an oval portion


64


angled corresponding to the angle of the helical slot


50


and an outer projection


66


. The cylindrical wall


54


includes an L-shaped slot


68


proximate the front end


62


and surrounding each driver arm


60


to provide a flexible arm


70


.




During assembly, as described below, the flexible arms


70


are deflected radially inwardly so that the driver


54


can be inserted in the actuator


36


with the driver arms


60


thereafter being received in the helical slots


50


. As such, linear movement of the actuator


36


is converted to rotary movement of the driver


38


, as illustrated by an arrow


72


.




The cam


40


comprises a generally cylindrical body


74


including frontwardly extending teeth


76


. The teeth


76


are receivable in the driver grooves


56


so that the cam


40


is rotational with the driver


38


as illustrated by an arrow


78


. The cam


40


has a circumferential cam track


80


. The cam track


80


comprises oppositely-directed helical paths


82


, one of which is shown, that are used to drive the pushers


28


and


30


in and out.




The assembly of the switch operator


20


is described with reference to

FIGS. 5-12

.




Referring initially to

FIG. 5

, the cam


40


is inserted rearwardly into the barrel


84


as shown. The pushers


28


and


30


are slid into a rear end of the barrel


84


. Each pusher


28


and


30


includes a radially-inwardly extending follower pin


88


and a guide pin


90


. After inserting the pushers


28


and


30


in the barrel


84


, the cam


40


is rotated 90 degrees. As a result, the follower pins


88


are received in and engage the cylindrical cam track


80


. The sequence of pusher action is determined by specific pattern of the cam track


80


. In the illustrated embodiment of the invention, when the actuator


36


is moved downwardly, the cam


40


rotates in a counter-clockwise direction, viewed downwardly in

FIG. 1

, so that the first pusher


28


is extended and the second pusher


30


remains in its normal or retracted position, see FIG.


2


. When the actuator


36


is pulled outwardly, as shown in

FIG. 3

, the cam


40


is rotated in a clockwise direction causing the second pusher


30


to extend and the first pusher


28


to remain in the normal or retracted position, as shown in FIG.


3


. As is apparent, the cam track


80


could be configured to provide a different sequence of operation of the pushers


28


and


30


.




Referring to

FIG. 6

, a torsion spring


93


is inserted into a front end of the cam


40


. The torsion spring


93


is adapted to bias the drive assembly


24


to the neutral or middle position, as shown in FIG.


1


.




The general configuration of the barrel


84


, cam


40


, pushers


28


and


30


and torsion spring


93


is known and has been used in connection with rotary knob-operated selector switches. Such a structure is described generally in European patent No. 0647954 B1, the specification of which is incorporated by reference herein.




Referring to

FIG. 7

, the front ring


86


is generally cylindrical and is slid over the barrel


84


in a direction indicated by the arrow


88


, to the position illustrated in phantom, to assemble the housing


22


. The front ring


86


includes a circumferential slot


91


at either side.




Referring to

FIG. 8

, a coil spring


92


is inserted in the driver


38


so that an end


94


pokes into the driver


38


, as shown in the lower portion of the figure which represents a bottom view of the driver


38


. Referring to

FIG. 9

, an assembly machine is used to squeeze the driver arms


60


inward and the driver


38


is then snapped into the actuator


36


until the driver arms


60


snap into the slot


50


at either side. During this assembly process the coil spring


92


is compressed so that it does not interfere with the flexible arms


70


. After insertion the spring


92


is released so that it acts as a spacer to prevent inward deflection of the flexible arms


70


and thus the driver arms


60


.




Referring to

FIG. 10

, the actuator


36


, having the driver


38


therein, is placed in an assembly machine which again depresses the driver arm


60


inwardly and the assembly is snapped into the front ring


86


, as illustrated by an arrow


96


. After this assembly step, the driver arm projections


66


extends outwardly into the front ring slots


90


to constrain linear movement of the driver


38


. Rotary movement of the actuator


36


is constrained by tabs (not shown) in the front ring


86


extending into the actuator grooves


48


. A ring gasket


98


incorporating a wiper seal is then positioned around the front ring


86


in a groove


100


, see also FIG.


10


A. Referring to

FIG. 11

, an apron


102


is illustrated. The apron


102


comprises a generally cylindrical wall


104


having an inwardly directed shoulder


106


supporting a pair of flexible tabs


108


, one of which is shown. The tabs


108


are received in the actuator slots


52


to provide a light-snap fit, as shown in FIG.


1


. The gasket


98


thus provides a wiper seal between the apron


102


and the front ring


86


. Referring to

FIG. 12

, the mushroom cap


26


is then threaded onto the actuator threaded collar


46


, as illustrated by an arrow


110


. A panel gasket


112


is then placed around the housing


22


for sealing the housing


22


in an enclosure panel, in use.




The contact block


32


, see

FIG. 13

, having an internal electrical switch, is mounted on base feet


114


of the housing


22


, see

FIG. 12

, using snap-fit toggle linkages


116


, as is known. Actuation of the cap


26


, which is coupled to the drive assembly


24


, selectively extends the pushers


28


and


30


from the housing


22


depressing a contact block plunger


118


causing the electrical switch to switch electrical states. The housing


22


can support two contact blocks


32


for separate actuation by the pushers


28


and


30


.




Thus, in accordance with the invention, linear movement of the cap


26


in one direction can be used to operate pushers


28


and


30


in either the same or in an opposite direction to selectively actuate contact blocks


32


. The shape of the helical cam track


80


determines whether left or right side contact blocks


32


, or both, are actuated when the cap is pushed in or pulled out. Moreover, the in and out positions can be maintained, or can allow the device to return to the middle position by selective assembly variations of the torsion spring, which is known and does not form part of this invention.



Claims
  • 1. A push-pull switch operator including:a housing; a rotary drive rotationally mounted in the housing and having a circumferential cam track; an actuator operatively coupled to the rotary drive for converting linear movement of the actuator to rotary movement of the rotary drive; a pusher received in the housing and having a follower pin riding in the cam track to convert rotational movement of the cylinder to linear movement of the pusher, the pusher for actuating an electrical switch; and a cap operatively coupled to the actuator for manually operating the actuator between in, middle and out positions to selectively operate the pusher.
  • 2. The push-pull switch operator of claim I wherein the rotary drive comprises a two-piece assembly having a driver operatively coupled to the actuator whereby linear movement of the actuator is converted to rotary movement of the driver and a cam operatively coupled the driver for rotation therewith and the cam track pattern is provided on the cam.
  • 3. The push-pull switch operator of claim 2 further comprising a torsion spring biasing the cam in the housing so that the actuator is normally in the middle position.
  • 4. The push-pull switch operator of claim 1 wherein the actuator comprises a cylinder including a helical slot and the rotary drive is telescopically received in the cylinder and has a driver arm received in the helical slot.
  • 5. The push-pull switch operator of claim 4 wherein the housing has a circumferential slot receiving the driver arm to constrain linear movement of the rotary drive.
  • 6. The push-pull switch operator of claim 1 further comprising a second pusher received in the housing and having a follower pin riding in the cam track to convert rotational movement of the cylinder to linear movement of the second pusher, the second pusher for actuating a second electrical switch.
  • 7. The push-pull switch operator of claim 6 wherein the cam track is configured to operate the two pushers in opposite directions.
  • 8. The push-pull switch operator of claim 7 wherein the cam track comprises oppositely oriented helical tracks.
  • 9. The push-pull switch operator of claim 4 wherein the driver arm extends radially outwardly from a flexible arm.
  • 10. The push-pull switch operator of claim 9 further comprising a spring in the rotary drive for preventing inward deflection of the flexible arm.
  • 11. The push-pull switch operator of claim 1 further comprising an apron snap fit to the actuator and surrounding a front end of the housing.
  • 12. The push-pull switch operator of claim 9 further comprising a ring gasket surrounding an outer wall at the front end of the housing in contact with the apron for sealing the housing.
  • 13. The push-pull switch operator of claim 12 wherein the ring gasket is formed of rubber.
  • 14. The push-pull switch operator of claim 12 wherein the ring gasket includes a wiper seal.
  • 15. A push-pull switch operator including:a housing; a drive assembly movably mounted in the housing and having a cam track; a cap operatively coupled to the drive assembly, the cap being manually, linearly actuable between in, middle and out positions; and a pusher received in the housing and having a follower pin riding in the cam track, the cam track being configured to convert linear movement of the cap in one direction to linear movement of the pusher in an opposite direction, the pusher for actuating an electrical switch.
  • 16. The push-pull switch operator of claim 15 wherein the drive assembly comprises an actuator, a driver operatively coupled to the actuator whereby linear movement of the actuator is converted to rotary movement of the driver and a cam operatively coupled the driver for rotation therewith and the cam track pattern is provided on the cam.
  • 17. The push-pull switch operator of claim 16 wherein the actuator comprises a cylinder including a helical slot and the rotary drive is telescopically received in the cylinder and has a driver arm received in the helical slot.
  • 18. The push-pull switch operator of claim 15 further comprising a second pusher received in the housing and having a follower pin riding in the cam track, the cam track being configured to convert linear movement of the cap in the one direction to linear movement of the second pusher in the one direction, the second pusher for actuating a second electrical switch.
  • 19. The push-pull switch operator of claim 18 wherein the cam track comprises oppositely oriented helical tracks.
US Referenced Citations (8)
Number Name Date Kind
2800806 Sangster Jul 1957
3581036 Dennison May 1971
4255633 Johnston et al. Mar 1981
4282414 Johnston et al. Aug 1981
4902865 Muller et al. Feb 1990
5408061 Martin Apr 1995
5605225 Schaeffer Feb 1997
5684670 Zimmermann et al. Nov 1997
Foreign Referenced Citations (1)
Number Date Country
647954 Apr 1995 EP