US3185786A - Snap-action electric switch - Google Patents

Description

May 25, 1965 w. D. WILSON SNAP-ACTION ELECTRIC SWITCH Filed March 22, 1963 3 Sheets-Sheet l INVENTOR. 144214D Mzsv ATTORNEX May 25, 1965 w. 0. WILSON SNAP-ACTION ELECTRIC SWITCH 3 Sheets-Sheet 2 Filed larch 22, 1963 w PM w 8 \1 6 4% M 6 w w w w Z Z M a a a 4M 9%. Z I 5 V w m I an d m w. 4 M M 2 w M 6 w w Ma ///////7 ATTORNEY.

May 25, 1965 w; D. WILSON SNAP-ACTION ELECTRIC SWITCH 3 Sheets-Sheet 25 Filed March 22, 1963 INVENTOR. 114414465 D. M490 A TTORNEY.

United States Patent 3,185,786 SNAP-ACTION ELECTRIC SWITCH Wallace D. Wilson, Middletown, N.J., assignor to Elastic Stop Nut Corporation of America, Union, N.J., a corporation of New Jersey Filed Mar. 22, 1963, Ser. No. 267,088 3 Claims. (Cl. ZOO-67) This invention relates generally to the art of switches, and more particularly to improved over-center switches of the type usually employed in combination with time delay control apparatus. The improved over-center switches of the present invention are particularly useful for opening or closing electrical circuits after a lapse of a predetermined time interval following the actuation of the time delay control apparatus by an operator.

It has been proposed to employ over-center type switches with time delay control apparatus. In substantially all of the prior art switches of this type, the switching lever member that is responsible for the switching action is securely fixed adjacent to one of its ends to a base or block member. Thus, to initiate a desired switching action, one must apply to the switching lever member a force of sufficient amplitude to bend it and to actuate, in turn, a contact assembly. While such prior art switches are suitable for certain applications, they leave something to be desired when the operating force that is transmitted to the switching lever member is limited and when very precise switching is required. It is an object of the present invention to provide improved over-center switches that may be actuated with relatively less force than corresponding prior art overcenter switches.

It is another object of the present invention to provide improved over-center switches having adjustable means for limiting the travel of a lever member so as to assure faster and more effortless switching.

A further object of the present invention is to provide improved over-center switches wherein the lever member is pivotably attached to adjacent parts for reducing the operating force required to actuate the switches.

Still a further object of the present invention is to provide improved over-center switches of the type described that are relatively simple in operation and construction, easy to manufacture, and highly efiicient in use.

These and other objects of the present invention are achieved in an over-center switch comprising a lever memher, and over-center spring means arranged in a manner to spring load the lever member for rotation in a plane over a limited distance about one of its ends, the latter end being pivotally mounted upon the base of the switch and functioning as a fulcrum for the lever member. One end of the over-center spring means is also pivotally mounted on the base, and its other end is pivotally engaged with the non-fulcrum end of the lever member in a manner whereby the lever member compresses the over-center spring means so as to bias the lever member in either of two opposite directions from a position of dead center. Thus, the lever member is biased for movement, with snap action, in the aforementioned two opposite directions from the position of the lever member when it compresses the over-center spring means a maximum. Motion transmitting means, usually from, and controlled by, time delay control apparatus are cooperatively coupled to the lever member to urge it in either of the two opposite directions. Adjustable stop means are provided to limit the distance travelled by the non-fulcrum end of the lever member in at least one direction, thereby increasing the sensitivity of the switch. Contact assembly means are cooperatively coupled to the lever member and are adapted to be actuated by the movement of the lever member.

The novel features of the present invention, as well as 3,185,786 Patented May 25, 1965 the invention itself, both as to its organization and method of operation, will be understood in detail from the follow ing description when considered in connection with the accompanying drawings in which similar reference characters rfeer to similar parts throughout, and in which:

FIG. 1 is a fragmentary longitudinal section through a time delay control apparatus and over-center switch illustrating the switch in one operative position in accordance with the present invention;

FIG. 2 is a cross-sectional view of the switch taken along the line 22 in FIG. 1;

FIG. 3 is a cross-sectional view of the switch, taken along the line 3-3 in FIG. 2, in one operative position thereof in accordance with the present invention;

FIG. 3a is a cross-sectional view of the switch, taken along the line 3a--3a in FIG. 2, in said one operative position thereof;

FIG. 4 is a view similar to FIG. 3, but illustrating the switch in another operative position thereof in accordance with the present invention;

FIG. 4a is a view similar to FIG. 3a, showing the switch in said another operative position thereof;

FIG. 5 is an exploded view of some parts of the switch to illustrate their pivotal mountings in accordance with the present invention;

FIG. 6 is a plan view of another embodiment of an over-center switch in accordance with the present invention;

FIG. 7 is a cross-sectional view of the switch shown in FIG. 6, taken along the line 7-7, and showing the switch in one operative position thereof;

FIG. 8 is a cross-sectional view of the switch shown in FIG. 6, taken along the line 8-8; and

FIG. 9 is a cross-sectional view similar to FIG. 7, but showing the switch in another operative position thereof.

Referring, now, particularly to FIG. 1 of the drawing, there is shown an over-center switch 10 cooperatively associated with time delay control apparatus 12 for actuating the switch 10 by means of a rod14, the latter being mounted for reciprocatory motion in a solenoid 16. The rod 14 is adapted to be reciprocated in the directions in dicated by the double headed arrow 18 by the time delay control apparatus 12 in a manner described in US. Patent No. 2,489,381, issued on November 29, 1949, to C. Lindahl for Time Delay Control Apparatus. The time delay apparatus 12 may also be of the type described in US. Patent No. 2,855,481, issued on October 7, 1958 to C. Lindahl for Time Delay Apparatus. Since the timedelay control apparatus 12 does not form a part of the present invention other than to supply a reciprocatory force to a lever member 20 for operating the switch 10, it will not be described herein, reference being made to the aforementioned patents for details of its operation.

The lower end of the rod 14 is of reduced diameter and has slidably mounted thereon a lost motion element in the form of a sleeve 22, the travel of which relative to the rod 14 is limited in the lower direction by :a riut 24, and in the upper direction by adjustable lock nuts 26 and 28 threaded on the rod 14. The lower end of the sleeve 22 is recessed to receive a spring 30 which acts to bias the sleeve 22 away'from the nut 24 and towards the lock nut 28. The outer surface of the sleeve 22 is channeled to provide end shoulders or oollans 32 and 34.

The sleeve 22 is disposed within an opening 36 in the lever member 20 so that the lever 20 may be rotated downwardly or upwardly about its fulcrum end 38 by the shoulders 34 and 32, respectively, when the rod 14 is reciprocated. The spring 30 acts in the nature of a booster spring which in eifec-t moves the lever member 20 across a dead center position from a position ahead of that at which the switch would be caused to pass its dead center position in the absence of the lost motion connection and booster spring 3%, in a manner to be explained hereinafter.

Referring, now, to FIGS. 2, 3, 3a, 4, 4a, and 5 the switch is shown comprising a base of insulating material adapted to be secured to the time delay control apparatus 12 by any suitable means, as by screws (not shown) engageable in threaded openings 42, 44, 46 and 48. The rod 14 extends through an elongated opening 50 in the base 40. Means are provided to mount the lever member 20 pivotally on the base 40. To this end, a block 52 of insulating material is fixed to the base 40 by screws 54 and 56 adjacent to an edge 58 of the base 40. The block 52 is formed with a V-groove 59 into which the fulcrum end 38 of the lever member 20 is pivoted. It will now be understood that the lever member 20 is adapted to rotate about its fulcrum end 38 so that its non-fulcrum end 60 describes an arc of rotation in a plane perpendicular to the base 40. The lever member 20 is preferably of spring steel.

Means are pnovided to spring load the lever member 20 and to cause it to move in opposite directions, with snap action, from a dead cent-er position. To this end, over-center spring means 62 are provided with a rod 64 having an enlarged head 66, the latter being formed with a V-g-r-oove 68. A knife edge '70, supported by a block '72 that is anchored to the base 40 by a screw 74, is positioned to pivotally engage the groove 68 in the head 66. The rod 64 is disposed loosely within .a helical spring 76, the spring 76 being contained with a hollow cylinder 78. The outside end of the cylinder '78 is formed with a V-groove 80 adapted to engage pivotally the non-fulcrum end 60 of the lever member 20. The block '72 is disposed opposite the block 52 and spaced from it a distance so that the spring 76 is compressed a maximum when the lever member 20 and the over-center spring means 62 are in position of substantially linear alignment, that is, in a position of dead center. Because of the spring loading provided primarily by the spring '76 of the over-center spring means 62, the lever member 20 may move upwardly or downwardly from the position of dead center with a snap action.

The lever member 20 has a winged member 82 of insulating material fixed to it adjacent to its non-fulcrum end 60, as shown in FIG. 5. The winged member 82 is formed with wings 84 and 86 extending in substantially opposite directions in the general plane defined by the lever member 20 and comprise means to move movable contact arms 88 and 90, the latter being provided with movable contacts 92 and 94, respectively.

The contact arms 88 and are anchored to the base 40 by screws 96 and 98 respectively. The screws 96 and 98 also engage cont- act strips 100 and 102 provided with screws 104 and 106, respectively, for making electrical connections with the contacts 92 and 94, respectively.

A pair of upper fixed contacts 108 and 110 are adapted to be engaged by the movable contacts 92 and 94, respectively, when the non-fulcrum end 60 of the lever member 20 is moved upwardly. The contacts 108 and 110 are fixed to the base 40 by resilient contact members 112 and 114 and by screws 116 and 118, respectively. Thus, electrical connections can be made to the fixed contacts 108 and 110 through the screws 116 and 118, respec tively.

When the lever member 20 is in its downward position, as illustrated in FIGS. 3 and 3a, the movable contacts 92 and 94 are adapted to be urged by their resilient arms 88 and 90 against lower fixed contacts 120 and 122 respectively. The fixed contacts 120 and 122 are fixed to the base 40 by resilient straps 124 and 126 and screws 128 and 130 (FIG. 2) respectively. Electrical c0nnections may be made to the lower fixed contacts 120 and 122 by means of screws 128 and 130 respectively.

The terminal position below dead center that the lever member 20 may move is determined by stop means cond sisting of a set screw 132 threaded through the base 40 and contacting the winged member 82. The sensitivity of the switch 10 can be adjusted by raising or lowering the screw 132 so that the amount of force necessary to rotate the lever member 20 upwardly past its dead center position is a desired magnitude. Thus, the screw 132 may be adjusted so that the lever member 20 is just below its dead center position, and the amount of force necessary to move it past its dead center position is essentially a minimum. The upper limit of travel of the lever member 20 is determined by the contact assemly including the movable contacts 92 and 94 and the upper fixed cont- acts 108 and 110, respectively. If desired, however, stop means (not shown) similar to the screw 132 may be positioned adjacent to the upper side of the lever member 20 for limiting its upper terminal position.

In ope-ration the time delay apparatus 12 is actuated by an operator and the lever member 20 is rotated downwardly about its fulcrum end 38 by the downward movement of the rod 14 in the time delay control apparatus 12, the upper collar 34- :of the sleeve 22 engaging the upper surface of the lever member 28 and rotating it downwardly past the dead center provided for by the over-center spring means 62. The lever member 20 then snaps to its lowest terminal position determined by the position of the adjustable screw 132. After a predetermined time, usually adjustable, controlled by the apparatus 12 the rod 14 begins to move upwardly causing the lower collar 32 of the sleeve 22 to engage the lower surface of the lever member 20 and rotates the latter upwardly past the dead center position of the over-center spring means 62. During the upward movement of the lever member 20 the spring 30 of the lost motion sleeve 22 is compressed thereby boosting the lever member across its dead center position with an additional force provided by the compression of the spring 30.

Referring, now, to FIGS. 6, 7, 8 and 9 there is shown another embodiment 10a of an over-center switch of the present invention. The switch 10a comprises a base of insulating material. A lever member 142 of spring steel has a fulcrum end 144 mounted within a groove 146 in a block 148 fixed to the base 140. A U-shaped over-center spring means 150 is formed with a notched end 152 that is pivotally mounted for rotation about a knife edge 154. The knife edge 154 is fixed to the base 140 by means of a screw 156. A notched end 158, oppo site to the notched end 156, of the over-center spring means 150 is pivotally engaged with the non-fulcrum end of the lever member 142 in a manner whereby the lever member 142 is spring loaded so that it can rotate about its fulcrum end 144 upwardly or downwardly, with snap action, past a dead center position. The rod 14 of the time delay control apparatus 12 is disposed within a slot 162 in the lever member 142 and the opposite shoulders 34 and 32 of the sleeve 22 are adapted to rotate the lever member 142 downwardly or upwardly in the same manner explained for the operation of the switch 10. The rod 14 extends through a hole 164 in the base 140.

A pair of movable contacts 166 and 168 is fixed adjacent to one of the ends of a pair of resilient arms 170 and 172, the other ends being anchored to the base 140 by screws 174 and 176 respectively. The arms 1'70 and 172 are adapted to be moved upwardly by the wings 178 and 180 of a winged member 182 respectively. A pair of upper fixed contacts 184 and 186 is fixed to the base 140 by resilient arms 188 and 190 by screws 192 and 194, respectively, as shown in FIG. 8. A pair of lower fixed contacts 196 and 198 is fixed to the base 140 in a position whereby they will be contacted by the movable contacts 166 and 168, respectively, when the lever member 142 is rotated downwardly.

A set screw 200 is threaded through the base 140 and adapted to engage the lower surface of the winged member 182 limiting the lower terminal position of rotation of the lever member 142. It will be understood that the screw 200 may be raised or lowered to position the lever member 142 below its dead center position so that a desired magnitude of force may be used to move the lever member 142 upwardly past its dead center position. The upper terminal limit of the lever member 14-2 may be determined by an adjustable screw (not shown) similar to the screw 2% or it may be determined by the contact assembly comprising movable contacts 166 and 163 and the fixed contacts 184 and 186 respectively.

The operation of the switch a is similar to that described for the switch 10. Motion of the rod 14, controlled by the time delay control apparatus ,12 initially moves the lever member 14 in one direction. For example, let it be assumed that the lever member 142 is initially rotated downwardly about its fulcrum end 144. The lost motion sleeve 22 will cause the lever member 142 to move downwardly past its dead center position until the winged member 182 engages the screw 200. After a predetermined time delay, controlled by the time control apparatus, the shoulder 32 of the sleeve 22 will urge the lever member 142 upwardly about its fulcrum end 144. Once past its dead center, the U-shaped over-center spring means 150 will cause the lever member 142 to move upwardly with a snap action until the movable contacts 166 and 168 engage the upper fixed contacts 184 and 186, respectively.

From the foregoing description there has been described over-center switches of the type wherein a lever member is connected pivotally at opposite ends thereof. Overcenter spring means are also connected pivotally at opposite ends thereof in a manner to spring load the lever member so that the resistance offered by the lever member in passing through a dead center position is reduced. Adjustable stop means have also been described for increasing further the sensitivity of the switch operation. Since various modifications of the present invention may be made without departing from the spirit and scope thereof, it is desired that the foregoing description shall be considered merely as illustrative and not in a limiting sense.

I claim:

1. In a switch of the type wherein a fixed contact is adapted to be engaged by a movable contact, and wherein said movable contact is moved by means including a spring loaded lever member, the improvement comprising, in combination,

(a) a base,

(b) said lever member having two opposite ends,

(0) means pivotally mounting one of said ends of said lever member on said base,

(d) over-center spring means having two opposite ends,

(e) means pivotally mounting one of said ends of said over-center spring means on said base, the other ends of said lever member and said over-center spring means pivotally engaging each other and compressing said over-center spring means to bias said lever member in either of two opposite directions from a dead center position,

(f) motion transmitting means engaging said lever member to urge it in either of said two opposite directions, and

(g) adjustable means disposed to engage and limit the movement of said lever member in one of said two opposite directions.

2. In a switch of the type wherein a fixed contact is adapted to be engaged by a movable contact, and wherein said movable contact is moved by means including a spring loaded lever member, the improvement comprising in combination,

(a) a base,

(b) said lever member having two opposite ends,

(0) means pivotally mounting one of said ends of said lever member on said base,

(d) over-center spring means having two opposite ends,

(2) means pivotally mounting one of said ends of said over-center spring means on said base, the other ends of said lever member and said over-center spring means pivotally engaging each other and compressing said over-center spring means to bias said lever member in either of two opposite directions from a dead center position,

(f) motion transmitting means engaging said lever member to urge it in either of said two opposite directions, and

(g) adjustable screw means threaded in said base and disposed to limit the movement of said lever member in one of said two opposite directions.

3. An over-center switch for use with time delay control apparatus having a motion transmitting member adapted to move in either of two opposite directions, said switch comprising,

(a) a base of insulating material,

(b) a lever member having two opposite ends,

(0) over-center spring means having two opposite ends,

(d) means pivotally mounting one of said ends of said lever member to said base for rotation thereabout in a plane,

(e) means pivotally mounting one end of said overcenter spring means to said base for rotation there about in said plane, the other ends of said lever memher and said over-center spring means being in pivotal engagement with each other,

(f) said lever member compressing said over-center spring means a maximum in a position of dead center, said motion transmitting member cooperatively engaging said lever member, whereby to move said lever member in either of said two opposite direction-s from said position of dead center,

(g) a contact assembly having means including a movable contact cooperatively engaged with said lever member for movement thereby,

(h) at least one fixed contact fixed to said base for engaging said movable contact, and

(i) adjustable screw means disposed in said base to limit the movement of said lever member in at least one of said two directions.

References Cited by the Examiner UNITED STATES PATENTS BERNARD A. GILHEANY, Primary Examiner. ROBERT K. SCHAEFER, Examiner.

Claims (1)

1. IN A SWITCH OF THE TYPE WHEREIN A FIXED CONTACT IS ADAPTED TO BE ENGAGED BY A MOVABLE CONTACT, AND WHEREIN SAID MOVABLE CONTACT IS MOVED BY MEANS INCLUDING A SPRING LOADED LEVER MEMBER, THE IMPROVEMENT COMPRISING, IN COMBINATION, (A) A BASE, (B) SAID LEVER MEMBER HAVING TWO OPPOSITE ENDS, (C) MEANS PIVOTALLY MOUNTING ONE OF SAID ENDS OF SAID LEVER MEMBER ON SAID BASE, (D) OVER-CENTER SPRING MEANS HAVING TWO OPPOSITE ENDS, (E) MEANS PIVOTALLY MOUNTING ONE OF SAID ENDS OF SAID OVER-CENTER SPRING MEANS ON SAID BASE, THE OTHER ENDS OF SAID LEVER MEMBER AND SAID OVER-CENTER SPRING MEANS PIVOTALLY ENGAGING EACH OTHER AND COMPRESSING SAID OVER-CENTER SPRING MEANS TO BIAS SAID LEVER MEM-

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