US3792212A

US3792212A - Snap action electric switch

Info

Publication number: US3792212A
Application number: US00172492A
Authority: US
Inventors: L Ludwig
Original assignee: Eagle Electric Manufacturing Co Inc
Current assignee: Cooper Wiring Devices Inc
Priority date: 1971-08-17
Filing date: 1971-08-17
Publication date: 1974-02-12
Anticipated expiration: 1991-02-12

Abstract

A snap action electric switch including a ball movable between alternate switching positions by a cam for controlling switching conditions. A coiled compression spring presses against the ball in a direction perpendicular to the direction of movement of the ball between said switching positions to assist the cam in snapping said ball to its alternate switching positions and means is provided to permit the ball to move relative to the spring between said switching positions so as to prevent said coiled compression spring from laterally flexing as said ball is moved to its alternate positions.

Description

United States Patent [191 Ludwig 1 Feb. 12, 1974 1 i SNAP ACTION ELECTRIC SWITCH [76] Inventor: Louis Ludwig, c/o Eagle Electric Mfg. Co. Inc., 23-10 Bridge Plaza 5., Long Island City, NY. 11101 [22] Filed: Aug. 17, 1971 [21 App]. No.: 172,492

[52] US. CL... 200/68, 200/67 AA, 200/67 A [51] Int 1101b 21/40 [58] Field of Search 200/67 R, 67 A, 67 G,

[56] References Cited UNITED STATES PATENTS 3,681,547 8/1972 Burch et a1. 200/68 3,032,620 5/1962 Siiberg 200/67 R 2,743,330 4/1956 Ludwig 200/67 A FOREIGN PATENTS OR APPLICATIONS 5/1970 Great Britain 200/68 1,006,040 4/1957 Germany 200/68 Primary ExaminerDavid Smith, Jr.

[ 5 7 ABSTRACT A snap action electric switch including a ball movable between alternate switching positions by a cam for controlling switching conditions. A coiled compres sion spring presses against the ball in a direction perpendicular to the direction of movement of the ball between said switching positions to assist the cam in snapping said ball to its alternate switching positions and means is provided to permit the ball to move relative to the spring between said switching positions so as to prevent said coiled compression spring from laterally flexing as said ball is moved to its alternate positions.

1 Claim, 3 Drawing Figures PATENTEUFEBIZW V 3.792.212

INVENTOR.

LOUIS LUDWLG ATTORNEYS SNAP ACT-ION ELECTRIC SWITCH BACKGROUND OF THE INVENTION 1. Field of the Invention Snap action electric switches with cam controlled ball operation.

2. Description of the Prior Art The present invention is an improvement over the snap action switch shown in US. Pat. No. 2,743,330. In that patent a ball was partially seated inside the coils at the free end of a coiled compression spring the other end of which was mounted on a base. A movable switch actuating element constituting a cam with an apex having two converging sides was provided. Shifting of the elements with the ball adjacent a first side of the apex caused the apex to depress the ball and compress the spring as the apex approached the ball. After the apex passed over the ball the spring snapped the ball to a position adjacent the second side of the apex. As the ball was moved from a position adjacent the first side of the apex to a position adjacent the second side of the apex the ball changed switching conditions in the switch. Reverse shifting of the ball resulted in a similar action, but in reverse. Because the ball was seated in the coils at the free end of the spring, said end moved with the ball from side to side. Such lateral motion of the spring slowed down the snap action that occurred after the apex of the cam traversed the ball in either direction.

In the disclosed structure of the patent the base end of the spring was so mounted that it could pivot whereby the entire length of the spring swung from side to side when the ball was shifted transversely. In a subsequent modified structure the base end was confined so that only a portion of the spring could swing or flex unrestrictedly from side to side. This further slowed down the snap action of the ball and sometimes caused the spring to be bent out of shape adjacent the zones of confinement which slowed down the snap action additionally.

SUMMARY OF THE INVENTION l. Purposes of the Invention It is an object of the present invention to provide an improved snap action electric switch of the aforesaid type which is not subject to the aforementioned defects.

More specifically, it is an object of the present invention to provide, in a switch of the character described, utilizing a compression spring and a ball as the structure for effecting switching operations, means for preventing the spring from laterally flexing and/or moving.

Another object of the present invention is to provide, in a snap action electric switch having a compression spring and a ball as the structure for effecting switching operations, means for allowing the ball to move as required to change switching conditions and to so move without causing a corresponding lateral movement of the free end of the spring.

It is an additional object of the invention to provide an improved snap action electric switch of the character described which constitutes relatively few and simple parts, is inexpensive to produce on a large scale, is easy to assemble and is efficient in operation.

Other objects of the invention will be apparent from the following description.

2. Brief Description of the Invention The foregoing and other objects according to the present invention are achieved in a snap action electric switch having a coiled compression spring with two ends. One end of the compression spring is mounted on the switch casing, being either pivoted of fixed. A cap is provided and includes a head having a flattopped table. A shank depends from the table. The shank is received in the coils at the free end of the compression spring. A ball rolls across the top of the table. A movable switch actuating element is provided which constitutes a cam having an apex with two converging sides for controlling the position of the ball to change the switching conditions in the switch. The compression spring urges the cap towards the ball and the ball toward the element causing the ball to always be squeezed between the element and the table top.

In one switching condition the ball is located on one side of the cam apex. As the switching actuating element is moved the cam apex rides over the ball causing the ball to depress the cap and compress the spring. After the cam apex has been sufficiently moved so as to have swept past the ball the compression spring act ing through the cap snaps the ball to a position adjacent the other side of the apex with the result that the switching conditions in the switch are changed. Since the ball rolls across the flat surface of the table top with relatively little friction therebetween insufficient force is supplied to the compression spring to cause the same to laterally flex.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings wherein like parts in the different figures are identified by the same reference numerals,

FIG. 1 is a perspective view ofa line cord snap action electric switch in accordance with the present invention;

FIG. 2 is a sectional view taken substantially along the line 22 of FIG. 1; and

FIG. 3 is a fragmentary sectional view taken in part along the line 22 of FIG. 1 showing, inter alia, the cap, ball and spring arrangement of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT In the drawings an improved line snap action electric cord switch 10 embodying the present invention is shown which is identical to the line snap action electric cord switch disclosed in copending US. Pat. application Ser. No. 97,1 15 except for an alteration in the cooperation between the compression spring and the control ball. It is to be appreciated that while the line cord switch 10 is disclosed as being identical to the switch in US. Pat. application Ser. No. 97,] [5, except as above noted, this is for purposes of illustration only and the principles of the present invention can be used with any snap action electric switch having a ball and a column type compression spring which acts on the ball.

Since switch 10, except as noted above, is disclosed in detail in US. Pat. application Ser. No. 97,1 15 a complete description of the portions of the switch which are common to the present application and US. Pat. application Ser. No. 97,115 is not necessary and is not set forth herein. However, to provide a background for the present invention certain portions of switch 10 are described herein which portions are also disclosed in US. Pat. application Ser. No. 97,115.

Switch includes a first casing half 12 and a second casing half 14. The casings are formed of insulating material and may be constructed by known molding techniques.

Casings

12 and 14 mate with each other to provide a housing and means is included to insure the proper alignment of the casing halves relative to each other.

A twin-wire line cord compartment is located in casing half 14.

A switch element compartment 16 is located in cas ing half 12. Also located in compartment 16 are conductors l8 and 20 which function in a manner that will hereinafter be described. Conductor 20 is held stationary in the casing half 12 and does not include any movable parts although it may be made of a resilient mate rial, e.g., springy brass, if desired. Conductor 20 has a fixed electrical contact 22 permanently secured to one end thereof for a purpose that will soon be readily apparent. Integral with the other end of conductor 20 are piercing points P which are adapted to pierce one end of an insulated cut stranded wire in the line cord that extends through casing half 12 and upon which switch 10 is mounted, the other insulated stranded wire in the line cord not being cut.

Conductor 18 includes a portion 21 which is partially curved, has a flat free end 23 and is resilient. A movable electrical contact 24 is permanently affixed to a surface of the free end 23. Base 26 of conductor 18 is in face to face contact with a conductor 27. End 26 is perpendicular to end 23. Conductor 27 includes a straight section which is in abutment with an end of casing 12 and which is the portion of said conductor in contact with conductor 18. Conductor 27 further includes an inclined section wedged between

tabs

28a and 28b whereby conductor 27 is stationary in casing half 12. Base 26 of conductor 18 is wedged between straight section of conductor 27 and posts 30 integral with casing half 12 so that base 26 is held stationary in casing half 12 while free end 23 is permitted to flex relative to said base 26. The unstressed position of conductor 18 is such that absent any external force applied thereto movable contact 24 is spaced from fixed contact 22. Piercing points P are integral with conductor 27 and pierce the other insulated end of the cut stranded wire which is not pierced by the piercing points integral with conductor 20.

A coiled compression spring 32 which has two ends, the same inherently being hollow, has one of its ends seated against base 26 of conductor 18. Base 26 may have a squat boss (hidden by the end of spring 32) to inhibit transverse shifting of base end of spring 32 although the same is not essential because in operation of the switch any force tending to displace said base end transversely is negligible. A cap 34 is provided and includes a table 36 having a flat top 38 which faces away from spring 32. Depending from table 36 is a shank 40 which is snugly received in the coils at the free end of spring 32. A rigid ball 42 is located in compartment l6 and is in continuous contact with flat table top 38. The surface of free end 23 remote from movable contact 24 faces ball 42.

A deltoid switch actuator 44 is rotatably secured on pin 43 to casing 12 so as to be oscillatable between the positions shown in solid lines and dotted lines (FIG. 2). Switch actuator 44 includes an apex 46 with

inclined sides

48 and 50 flanking said apex and converging thereto. A shoulder 52 integral with casing 12 is positioned so as to limit the movement of ball 42 towards one side of said casing remote from free end 23. The remaining two apices of actuator 44 are arranged to a]- ternately project from the switch housing through slots 54. One such apex projects from one side of the housing in off position of the switch and the other from the other side in on position. Motion of the actuator in opposite directions is limited by abutment against portions of the casing half 12.

In use, ball 42 is always in contact with table top 38 and spring 32 is always exerting a force on cap 34 urging said cap away from base 26. With the ball positioned as shown in solid lines, said ball is wedged by side 50 against conductor 18 so as to flex free end 23 outwardly until movable contact 24 engages fixed contact 22 to complete a circuit in the on position of the switch. When actuator 44 is rotated in a counterclockwise direction as viewed in the figures to the of position of the switch, side 50 rides over ball 42 causing said ball to move towards base 26 of conductor 18. This causes cap 34 to further compress spring 32. Sufficient rotation of actuator 44 causes apex 46 to ride over ball 42 which results in maximum compression of spring 32.

After apex 46 has swept past ball 42, the ball comes in contact with side 48 whereupon spring 32 through cap 34 snaps the ball to a position where the ball is wedged by cap 34 between side 48 and shoulder 52. The resiliency of conductor 18 shifts movable contact 24 away from fixed contact 22 so that

conductor

18 and 20 are no longer in circuit with each other and the switch is in off position. The position of actuator 44 and ball 42 in on position are shown in solid lines in FIG. 2 and in of position in dotted lines in the same figure.

It is to be appreciated that as actuator 44 is rotated in a counterclockwise direction with ball 42 initially maintaining conductors l8 and 20 in circuit with each other, said ball is moved towards base 26 in a substantially straight path by side 50, maintaining contact with the flat end 23 of conductor 18. After apex 46 rides over ball 42 the ball is moved away from base 26 up side 48 by spring 32 until it is wedged by cap 34 between shoulder 52 and side 48. Ball 42 at all times remains in contact with and is squeezed between flat top 38 of table 36 and actuator 44. It can thus be seen that ball 42 moves (rolls) from adjacent one edge of flat table top 38 to against the opposite edge thereof as a result of actuator 44 being rotated to break the circuit between

conductors

18 and 20. There is very little friction between ball 42 and flat table top 38 as the ball moves (rolls) across the surface and thus in essence no lateral force is applied to cap 34 or spring 32. Consequently, spring 32 does not laterally flex and/or move.

When it is desired to re-establish contact between

conductors

18 and 20 actuator 44 is rotated in a clockwise direction, forcing ball 42 to the position seen in solid lines, to wit, in contact with flat table top 38, side 50 and free end 23 of conductor 18 so as to force contact 24 into engagement with contact 22 by flexing free end 23 outwardly. As ball 42 is brought to this position it moves along flat table top 38 until contacting conductor 18, in a manner analogous to that described previously when the circuit between

contacts

22 and 24 is broke.

From the foregoing description it is readily clear that spring 32 never flexes or moves in a lateral direction when ball 42 is moved to effect changes in the contact conditions in switch thus overcoming one of the drawbacks noted in prior art snap action electric switches.

It thus will be seen that there is provided a snap action electric switch which achieves the various objects of the invention and which is well adapted to meet the conditions of practical use.

As various possible embodiments might be made in the embodiment above set forth, it is to be understood that all matter herein described or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

Having thus described the invention there is claimed as new and desired to be secured by Letters Patent:

1. A snap action electric switch comprising a casing, a coiled compression spring having a first end and a second end, electrical switching means, said electrical switching means including a first conductor and a second conductor, a first contact located on said first conductor, a second contact located on said second conductor with said contacts being in registry with each other, said first conductor including a first flat section, said first contact being located on said first flat sections, said first conductor including a curved section which extends from said first section to a second section, means securing said second section so as to prevent said second section from moving relative to said casing, a rolling element movable between first and second switching positions, said element in said second switching position abutting said first section of said first conductor and maintaining said first contact in abutment with said second contact, .said first conductor being resilient so that in the absence of any force applied thereto said first contact located thereon is spaced from said second contact, means affixed to said first conductor section section for securing said first end of said coiled compression spring from movement relative to said casing, said coiled compression spring having an axis which is transverse to the direction of movement of said element, actuator means for moving said element between its switching positions, means affixed to said second end of said coiled compression spring and in engagement with said rolling element for enabling said coiled compression spring to urge said element to its switching positions while preventing the second end of said coiled compression spring from laterally moving as said element is moved between its switching positions, limiting means for limiting the extent of movement of said element as said element reaches its first switching position so that the location of the engagement between said element and said enabling means is within the confines of said coiled compression spring in the first switching position, and said switching means limiting the movement of said element as it reaches its second switching position so that the location of the engagement between said element and said enabling means is within the confines of said coiled compression spring in its second switching position.

Claims

1. A snap action electric switch comprising a casing, a coiled compression spring having a first end and a second end, electrical switching means, said electrical switching means including a first conductor and a second conductor, a first contact located on said first conductor, a second contact located on said second conductor with said contacts being in registry with each other, said first conductor including a first flat section, said first contact being located on said first flat sections, said first conductor including a curveD section which extends from said first section to a second section, means securing said second section so as to prevent said second section from moving relative to said casing, a rolling element movable between first and second switching positions, said element in said second switching position abutting said first section of said first conductor and maintaining said first contact in abutment with said second contact, said first conductor being resilient so that in the absence of any force applied thereto said first contact located thereon is spaced from said second contact, means affixed to said first conductor section section for securing said first end of said coiled compression spring from movement relative to said casing, said coiled compression spring having an axis which is transverse to the direction of movement of said element, actuator means for moving said element between its switching positions, means affixed to said second end of said coiled compression spring and in engagement with said rolling element for enabling said coiled compression spring to urge said element to its switching positions while preventing the second end of said coiled compression spring from laterally moving as said element is moved between its switching positions, limiting means for limiting the extent of movement of said element as said element reaches its first switching position so that the location of the engagement between said element and said enabling means is within the confines of said coiled compression spring in the first switching position, and said switching means limiting the movement of said element as it reaches its second switching position so that the location of the engagement between said element and said enabling means is within the confines of said coiled compression spring in its second switching position.