US3770926A

US3770926A - Selector switch actuator with part of detent means integral with actuator cam

Info

Publication number: US3770926A
Application number: US00275602A
Authority: US
Inventors: V Wanner
Original assignee: Allen Bradley Co LLC
Current assignee: Allen Bradley Co LLC
Priority date: 1972-07-27
Filing date: 1972-07-27
Publication date: 1973-11-06
Anticipated expiration: 1990-11-06
Also published as: CA971611A; DE2337135A1; FR2195055A1; FR2195055B1

Abstract

A rotor of a switch actuator includes a selector cam having a serrated cam surface which mates with the serrated cam surface on a selector cam follower. The selector cam follower is slidably retained within an actuator sleeve which surrounds the rotor and the cam follower is forced into mating engagement with the selector cam by a bias spring. The force of the spring is translated by the serrated cam surfaces into a torque which provides a snap-action when the rotor is rotated between its selectable positions.

Description

United States Patent [1 1 Wanner 1 Nov. 6, 1973 SELECTOR SWITCH ACTUATOR WITH PART OF DETENT MEANS INTEGRAL WITH ACTUATOR CAM [75] Inventor: Vernon W. Wanner, Milwaukee,

Wis.

[73] Assignee: Allen-Bradley Company, Milwaukee,

' Wis.

[22] Filed: July 27, 1972 21 Appl. No.: 275,602

[52] US. Cl. 200/166 SD, 200/153 L, 200/172 R, 74/1041, HOlh/3/42 [51] Int. Cl. H0lh 3/50 [58] Field of Search 200/153 J, 153 L, ZOO/156, 63 R, 65, 166 SD, 77, 172 R; 74/l0.4l

[56] References Cited UNITED STATES PATENTS 7/1964 Kane et al. 200/153 L X 3/l970 Tillack et al 200/166 SD 2,908,777 10/1959 Brown 200/65 X 3,193,653 7/1965 Cope ZOO/I66 SD FOREIGN PATENTS OR APPLICATIONS 1,132,838 3/1957 France 200/172 R Primary Examiner-J. R. Scott Assistant ExaminerRobert A. Vanderhye Att0rneyBarry E. Sammons et al.

[57] ABSTRACT A rotor of a switch actuator includes a selector cam having a serrated cam surface which mates with the serrated cam surface on a selector cam follower. The selector cam follower is slidably retained within an actuator sleeve which surrounds the rotor and the cam follower is forced into mating engagement with the selector cam by a bias spring. The force of the spring is translated by the serrated cam surfaces into a torque which provides a snap-action when the rotor is rotated between its selectable positions.

10 Claims, 7 Drawing Figures SHEET 10F 4 PATENTEBNHY sms 3770.926

SHEET 2 OF 4 SELECTOR SWITCH ACTUATOR WITH PART OF DETENT MEANS INTEGRAL WITH ACTUATOR CAM BACKGROUND OF THE INVENTION The invention relates to control switches, and more particularly, to switches of the rotary selector type commonly attached to control panels associated with electrical apparatus.

Selector switches are used in industry where they are employed to control electrical equipment. The switches are commonly mounted to the front panel of enclosures for such electrical equipment as motor starters, motor speed control circuits, and numerical control directors. The switches are sealed to prevent the entry of oil and other foreign material into the equipment enclosure.

Prior selector switches include detent mechanisms which operate to provide a plurality of switch positions. Such detent mechanisms are located within the actuator section of the switch and include a ball which is spring biased against a surface which contains a plurality of detents. There are a number of detent mechanism arrangements, including ones in which the ball is spring biased in the direction of the central switch axis, as illustrated in U.S. Pat. Nos. 2,798,908 and 2,814,681, and ones in which the ball is spring biased radially outward from the central axis, as illustrated in U.S. Pat. No. 2,947,827. After a period of use, such prior detent mechanisms often fail to provide a crisp, snap-action which is highly desirable in industrial environments where noise and vibration are present.

SUMMARY OF THE INVENTION The present invention relates to an improved selector switch actuator mechanism which provides a positive switching force between selectable positions. Specifically, the switch actuator includes an actuator sleeve having a central opening about an acutator axis, an actuator rotor journaled within the central opening of the actuator sleeve and having an integrally formed actuator cam which communicates with the contact section of the switch, a selector cam formed on the actuator rotor around its outer surface, a selector cam follower disposed around the actuator rotor and slidably retained within the central opening of the actuator sleeve, and a bias spring positioned to force the selector cam follower into mating engagement with the selector cam. The selector cam and selector cam follower each have serrated cam surfaces which mate with one another in a plurality of rotor positions. The serrations on the cam surfaces provide angulated surfaces which translate the spring bias force into a rotary torque which snaps the rotor into one of its selectable positions.

A general object of the invention is to provide a selector switch actuator mechanism which provides a crisp, snap-action when operated. The relatively large bias spring is located within the central opening of the actuator sleeve and around the actuator rotor. It provides a substantial longitudinal force along the switch axis which is translated to a rotary force, or torque, by the serrated cam surfaces.

Another object of the invention is to provide a selector switch actuator which requires a minimal number of parts and which is easily assembled on a mass production basis.

The foregoing and other objects and advantages of the invention will appear from the following descrip tion. In the description reference is made to the accompanying drawings which form a part hereof and in which there is shown by way of illustration a preferred embodiment of the invention. Such embodiment does not necessarily represent the full scope of the invention, and reference is made to the claims herein for interpreting the breadth of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a selector switch which incorporates the invented switch actuator,

FIG. 2 is a view in cross section of the switch of FIG. 1 taken on the plane 22,

FIG. 3 is an exploded perspective view of the switch of FIG. 1,

FIG. 4 is an end view of the actuator sleeve which forms a part of the switch of FIG. 1,

FIG. 5 is a view in cross section of the actuator sleeve of FIG. 4 taken on the plane 55,

FIG. 6 is a view in cross section similar to FIG. 2, but showing the switch between two of its selectable positions, and

FIG. 7 is a pictoral view with parts cut away of an alternative rotor arrangement and its associated selector knob.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIGS. 1, 2 and 3, a selector switch adapted for attachment to a control panel includes an actuator section 1 and a contact block section 2. The contact block section 2 includes a pair of switch cartridges, each of which contains two sets of electrical contacts. The contacts in each cartridge are operated by a plunger 3 connected for reciprocal motion in the direction of the switch axis and biased in a forward, or unactuated position by a spring 4. The contact block section 2 is an integral unit which is separable from the actuator section 1 and in which the cartridges therein may be interchanged to provide different modes of operation. Such separable contact block sections in which the contacts are opened or closed by the operation of a plunger are well known in the art and reference is made to the copending U.S. patent application Ser. No. 270,420 for a more detailed description of the contact block section 2.

Referring to FIGS. 2-5, the actuator section 1 includes an actuator sleeve 5 made of a zinc alloy and including an integrally formed rectangular bearing plate 6. The bearing plate 6 extends radially outward from the surface of the actuator sleeve 5 atits back end, and a set of four openings 7 are formed therethroughto receive a set of four mounting screws 8. A central, circular opening is formed completely through the actuator sleeve 5 along and concentric about a central axis 9. The central opening is necked at its forward end by a flange 10 which extends radially inward from the sleeve 5 to form a seat lll for an annular shaped gasket I2. A second constriction of lesser extent is formed immediately behind the flange 10 to provide an annular shaped thrust surface 13, and a pair of opposing keyways 14 are formed along the inner surface of the actuator sleeve 5, beginning from its back surface and terminating at a point intermediate its ends.

The four mounting screws 85 extend through the back surface of the bearing plate 6 and through a set of four openings formed in an actuator frame 16. Referring to FIGS. 2 and 3, the actuator frame 16 is generally rectangular in shape and is formed from molded plastic. It includes a central opening concentric with the central axis 9, and an annular shaped recess 17 formed on its front surface concentric with the central axis 9. The recess 17 defines a circular cavity which is larger in diameter than the central opening and which is lo cated immediately behind the bearing plate 6. A pair of stops 18 are integrally formed to the frame 16 and extend radially inward into this cavity. A ring 19 is also integrally formed to the actuator frame 16. The ring 19 is concentric about the central axis 9 and extends from the back surface of the actuator frame 16 into a circular recess 20 which is formed on the front surface of the contact block section 2.

Referring to FIGS. 1-3, the assembled contact block section 2, actuator frame l6 and actuator sleeve 5 are mounted to a control panel 23 by a fastener mechanism carried by a rectangular shaped cover 22. A set of four rubber gaskets 23 are placed over the actuator sleeve 5 and against the front surface of the bearing plate 6. The actuator sleeve 5 is then inserted through an opening in the control panel 21 and the cover 22 is fitted over the sleeve 5 and attached to the panel 21l. A rectangular face plate 31 fits within the cavity defined by the cover 22 and is retained against the forward end of the actuator sleeve 5 by a selector knob 30. For a more detailed description of the fastening means used to connect the selector switch to the control panel, reference is made to the above-cited copending United States patent application.

Rotatably retained within the central opening of the actuator sleeve 5 is a rotor 24. Referring to FIGS. 2 and 3, the rotor 24 is formed from molded plastic and includes a circular, cylindrical stem portion 25 which extends forward through the constricted opening defined by the flange 10 at the forward end of the actuator sleeve 5. The stem 25 has a necked portion near its forward end which forms a seat 26 for an O ring 27.

Referring to FIGS. 2 and 7, a central opening 45 is formed through the rotor 24 and the knob 3i) is inserted into the forward end of this opening. The knob 30 includes a pair of arms 47 which extend into the opening 45 and expand radially outward to engage a retainer surface 46 formed by a constriction in the opening 45. A circumferential groove 48 is formed on the outer surface of each arm 47 to define a knuckle 49 which engages the retainer surface 86. A plastic insert 50 is wedged between the arms 47 to increase their rigidity and to thereby enhance their holding power when the knob 30 is snapped into place.

The rotor 24 also includes an integrally formed retainer flange 32 which extends radially outward from its surface and into the cavity defined by the recess 17. The rotor 24 is thus restrained against axial motion by the back surface of the bearing plate 6 and the recessed front surface of the actuator frame 16. A limit tab 33 is integrally formed to the retainer flange 32 and extends radially outward therefrom over a sector of its circumference. The limit tab 33 rides within the recess 17 and engages the stops 18 therein to inhibit rotation of the rotor 24. integrally formed to the rotor 24 immediately behind the retainer flange 32 is an actuator cam 34. The actuator cam 34 includes a contoured cam surface 35 which bears against the ends of the plungers 3 extending from the contact block section 2. The cam surface 35 is comprised of a series of complex surfaces which translate the rotational motion of the rotor 24 into the desired axial motion of the plungers 3. This method of actuating the switches in the contact block section 2 is well known in the art, the numerous cam surfaces 35 are available to provide the desired switching operation.

Referring to FIGS. 2 and 6, a selector cam 36 is integrally formed to the rotor 24 and is positioned immediately forward of the retainer flange 32. The selector cam 36 extends around the outer surface of the rotor 24 and includes a serrated cam surface 37 which faces axially forward. Cooperating with the selector cam 36 is a separate, annular shaped selector cam follower 38 which is disposed around the stem 25 of the rotor 24. The selector cam follower 38 is restrained against rotation by a pair of integrally formed opposing keys 39 which extend radially outward from its surface into the keyways 14 formed on the inner surface of the actuator sleeve 5. The selector cam follower 38 is thus slidably mounted to the actuator sleeve 5 for limited motion in the direction of the central axis 9. The selector cam follower 38 includes a serrated cam surface 40 which faces the cam surface 37 on the selector cam 36 and which mates therewith in a plurality of positions.

As shown in FIG. 2, the selector cam follower 38 is biased into mating engagement with the selector cam 36 by a bias spring 41. The bias spring 41 is disposed around the rotor stem 25 and is positioned between the selector cam follower 38 and a steel washer 42 which rests against the thrust surface 13 formed on the interior of the actuator sleeve 5. The bias spring 41 is slightly compressed to provide a force which acts in the direction of the central axis 9 to thrust the selector cam follower 38 against the selector cam 36.

When the rotor 24 is rotated, as shown in FIG. 6, the selector cam 36 is revolved out of mating engagement with the selector cam follower 38. The selector cam follower 38 is thereby translated axially forward against the force exerted by the bias spring 41. The

serrated cam surface

37 and 40 present a series of angulated surfaces which translate the axial force of the bias spring 41 into a torque. This torque resists rotation of the rotor 24 away from each selectable position and the operator must apply a torque sufficient to overcome this resistive torque to reach a point midway between selectable positions. At this midpoint, the slope of the engaging cam surfaces 37 and 40 changes and an opposite torque is produced to aid rotation into the next selectable position. A snap-action is thus provided.

A selector switch actuator has been described which provides a pronounced snap-action. The serrated cam surfaces 37 and 40 are held in mating engagement by a relatively large bias spring 41, and the axial spring force is translated into a torque when the angulated cam surfaces are rotated out of mating engagement. By providing a plurality of mating positions, a plurality of selectable positions are thus provided. It should be apparent to those skilled in the art that variations can be made in the shape of the cam surfaces 37 and 40 without departing from the spirit of the invention. For example, the number of serrations can be varied to provide the desired number of selectable positions and the desired amount of snap-action can be altered by changing the depth of the serrations. Such an alternative arrangement is illustrated in FIG. 7 in which a cam surface 51 formed on the selector cam 36 and a mating cam surface 52 formed on the selector cam follower 38 have only two serrations. The limit tab 33 is positioned such that the rotor 24 is restrained against rotation out of one selectable position. A momentary operation results in which the rotor 24 may be rotated away from its single selectable position, but when released, it is driven back into mating engagement with the selector cam follower 38 by the force of the bias spring 41.

I claim:

1. In a selector switch having a contact section adapted for operation by a rotatable actuator cam, a switch actuator comprising:

an actuator sleeve connected to said contact section and having a central opening concentric about an actuator axis;

a rotor journaled within the central opening of the actuator sleeve for rotation therein about the actuator axis, said actuator cam being integrally formed on the back end of said rotor;

a selector cam integrally formed on said rotor around its outer surface and axially forward of said actuator cam, said selector cam forming a first serrated cam surface which is directed along said central axis;

a selector cam follower connected within the central opening of the actuator sleeve for sliding motion along said central axis, said selector cam follower being disposed around said rotor and providing a second serrated cam surface which is directed along said central axis and opposes said first serrated cam surface; and

a bias spring contained within the central opening of the actuator sleeve and disposed around the rotor, said bias spring being disposed between a thrust surface formed on said actuator sleeve and said selector cam follower to provide an axially directed bias force which slides the selector cam follower into engagement with said selector cam.

2. In a selector switch having a contact section adapted for operation by a rotatable actuator cam, a switch actuator comprising:

an actuator sleeve having a central opening concentric about an actuator axis;

a rotor journaled within the central opening of the actuator sleeve for rotation therein about the actuator axis, said rotor being rigidly connected to the actuator cam;

a selector cam rigidly connected to the rotor and disposed around its outer surface to provide a first cam surface which is directed along the actuator axis;

a selector cam follower slidably connected within the central opening of the actuator sleeve and disposed around the outer surface of the rotor to provide a second cam surface which faces said first cam surface, said selector cam follower being restrained from rotating about said actuator axis; and

a bias spring contained within the central opening of the actuator sleeve and disposed around the rotor to provide a bias force which acts in the direction of the actuator axis to slide the selector cam follower into engagement with the selector cam.

3. The actuator of claim 1 wherein the first cam surface is serrated to provide a plurality of selectable positions and to provide a plurality of angulated surfaces against which the selector cam follower bears when the rotor is rotated between selectable positions, said angulated surfaces operating to translate the spring bias force into a torque which tends to rotate the rotor into one of its selectable positions.

4. The actuator as recited in claim 1 wherein the second cam surface is serrated to provide a plurality of selectable positions and to provide a plurality of angulated surfaces against which the selector cam bears when the rotor is rotated between selectable positions and a key is formed on the selector cam follower which engages a keyway formed on the interior surface of said actuator sleeve to prevent rotation of the selector cam follower about said actuator axis.

5. The actuator of claim 1 in which said rotor includes a stem portion which extends forward through said central opening to attach with a knob, and in which said selector cam follower and said bias spring surround said stem portion and are contained within a cavity defined by the outer surface of said stem portion and the inner surface of said actuator sleeve.

6. The actuator of claim 5 in which a thrust surface is formed at the forward end of said cavity by a constriction in said actuator sleeve, and said bias spring is positioned between said thrust surface and said selector cam follower.

7. The actuator of claim 6 in which a pair of keyways are formed in the axial direction on the inner surface of said actuator sleeve and a pair of keys are formed on said selector cam follower which extend radially outward into said keyways to restrain said selector cam follower from rotating about said actuator axis, but to allow a sliding motion along said actuator axis.

8. The actuator of claim 5 in which an opening is formed in said rotor stem and a retaining surface is formed by a constriction in this opening near its forward end, and in which said knob includes a pair of arms which extend into said opening in said rotor stem and into engagement with said retaining surface.

9. The actuator of claim 1 which includes: an actuator frame connected to said actuator sleeve and said contact section; and a retainer flange connected to said rotor and extending radially outward therefrom, wherein a recess is formed in the front surface of said actuator frame to receive said retainer flange and an opening is formed in said actuator frame through which the actuator cam communicates with the contact section.

10. The actuator of claim 9 in which said actuator cam is disposed axially to the rear of said retainer flange, said selector cam is disposed axially forward of said retainer flange, and said actuator sleeve includes a bearing plate disposed axially forward of said actuator frame.

2223 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 2,770,926 Dated Novembet6. 1973 Inventor(s) Ver non W. Wanner It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Change the title, from"Selector Switch Actuator With Part of Detent Means Integral With Actuator Cam to Selector Switch Actuator Claim 3, line 1, A change claim 1 to claim 2 Claim 4, line 1, A change claim 1 to claim 2 Claim 5, line 1, i I change claim 1 to claim 2 Claim 9, line l, change claim 1 to claim 2 Signed and sealed this 16th day of July 197A (SEAL) Attest:

McCOY M. GIBSON, JR. 0, MARSHALL DANN Attesting Officer Commissioner of Patents

Claims

1. In a selector switch having a contact section adapted for operation by a rotatable actuator cam, a switch actuator comprising: an actuator sleeve connected to said contact section and having a central opening concentric about an actuator axis; a rotor journaled within the central opening of the actuator sleeve for rotation therein about the actuator axis, said actuator cam being integrally formed on the back end of said rotor; a selector cam integrally formed on said rotor around its outer surface and axially forward of said actuator cam, said selector cam forming a first serrated cam surface which is directed along said central axis; a selector cam follower connected within the central opening of the actuator sleeve for sliding motion along said central axis, Said selector cam follower being disposed around said rotor and providing a second serrated cam surface which is directed along said central axis and opposes said first serrated cam surface; and a bias spring contained within the central opening of the actuator sleeve and disposed around the rotor, said bias spring being disposed between a thrust surface formed on said actuator sleeve and said selector cam follower to provide an axially directed bias force which slides the selector cam follower into engagement with said selector cam.

2. In a selector switch having a contact section adapted for operation by a rotatable actuator cam, a switch actuator comprising: an actuator sleeve having a central opening concentric about an actuator axis; a rotor journaled within the central opening of the actuator sleeve for rotation therein about the actuator axis, said rotor being rigidly connected to the actuator cam; a selector cam rigidly connected to the rotor and disposed around its outer surface to provide a first cam surface which is directed along the actuator axis; a selector cam follower slidably connected within the central opening of the actuator sleeve and disposed around the outer surface of the rotor to provide a second cam surface which faces said first cam surface, said selector cam follower being restrained from rotating about said actuator axis; and a bias spring contained within the central opening of the actuator sleeve and disposed around the rotor to provide a bias force which acts in the direction of the actuator axis to slide the selector cam follower into engagement with the selector cam.