US1970432A - Switch operating mechanism - Google Patents

Description

1934. w. E. PORTER 1,970,432

SWITCH OPERATING MECHANISM Filed NOV. 12, 1931 Inventor: Wil lard E. Port-e1",

His Attorney.

' ditions are Patented Aug. 14, 1934 1,970,432 swrrcn OPERATING MECHANISM Willard E. Porter, Swampscott,]Mass., assignor to General Electric Company, a corporation of New York Application November 12, 1931, Serial No. 574,606

4 Claims. (01, 74-44) My invention relates to improvements in mechanisms such as those employed in electric switches for quickly throwing a switch from closed to open position and vice-versa. The invention is particularly useful in a time switch where a slow motion timing device is employed to operate the mechanism. In a common form of tumbler or toggle switch operating mechanism, a spring biased lever system is moved from one side to the other side of a dead center or neutral position, the idea being to obtain-a snap action for operating switch contacts upon which the mechanism operates. Where the mechanism isdirectly operated by hand, as in a push-button switch, there is usually little difliculty in obtaining the desired snap action and a corresponding quick, positive opening or closing of the switch contacts, because the operating force is suddenly applied. However, if the operating force is slowly applied, as it is in a time switch, there is a period in the slow movement of the mechanism through the neutral position where the pressure on the switch contactsis slowly reduced before the switch is actually opened. 1 Such condetrimental, because they cause changes in contact resistance, often a slight but undesirable relative movement of the contacts, undesirable heating, and occasionally a slight separation of and burning of the contacts, before the main opening movement actually occurs. The above conditions may be augmented by small changes inthe positions of parts due to wear, vibration, variations in spring tension due to temperature changes and fatigue, or an increase in friction of the movement of the parts, due to dirt, wear, etc. incident to service conditions. The primary object of my invention is to provide a tumbler or toggle switch mechanism for time switch service with means for positively locking the switch operating lever in its circuit closing and circuit opening positions until the remainder of the operating mechanism has passed through and beyond the neutral position and has built up an appreciable operating force for the opposite direction of movement, at which time the switch operating lever is unlocked and snaps to the new position. i 5

The features of my invention-which are believed to be new and patentable will be pointed outin the claims appended hereto. For a better understanding of my invention reference is made in the following description to the accompanying drawing, which shows a time switch including a toggle mechanism to which my invention has been applied.

In the time switch of Fig. 1, 10 represents any form of timing motor suitably geared to a 24-hour timing dial 11 so as to operate the latter in a clockwise direction at a uniform slow speed of one revolution in 24 hours; 12 represents a stationary pointer for indicating the time of day on the dial; and 13 and 14 are arms moved with the 'dial' for operating the toggle mechanism shown above the dial, These arms are adjustable about the dial so as to open and close the switch of the mechanism at the desired predetermined times of day or night. These arms have rearwardly extending pins 15 and 16 at different radial distances from the axis of the dial for moving the lever arm 17 up and down. Lever 1'7 is pivoted at 18, and is provided with a roller 19 intermediate its ends. Pin 15 of arm 13 moves against the under side of roller 19 and shoves the lever 1'7 upward as arm 13 rotates past this point. Pin 16 of arm'l l moves against the upper side of roller 19 and moves arm 17 downward as arm 14 rotates past this point.

The'switch contacts upon which the toggle mechanism operates are represented at 20 and 21, the latter being the movable contact, which is here shown in the closed position against contact 20. These contacts are mounted on an insulating support 22 by the connecting lugs 23 and 24. Itwillbe noted that the switch contacts assembly just described may be removed as a unit and replaced by a newunit at any time without disturbing any other part of the apparatus. As here shown, the movable contact 21 is normally biased to" a closed position by its own resiliency, and has an extension 25, against the under side of which a pin 26 in the switch operating lever 2'1 of the toggle mechanism moves when the switchis to be opened thereby. The switch contact parts may obviously take a variety of forms other than that shown, and the association with the mechanism may vary without departing from the novel locking features of the toggle mechanism to be described.

3 The toggle mechanism per se consists of the switch operating lever 27, previously referred to, which is pivoted on stationary pin 28, thelever 29 secured to shaft 30, which is rotatable about its own axis, with lever 29 and the resilient lost motion toggle connection between the long ends of levers 2'7 and 29 consisting of the laterally extending pins 31 and 32 with the spring 33 between them. The up and down movement of the toggle operating lever 17 is multiplied somewhat and conveyed to toggle lever arm 29 by the pin 34 secured in the outer end of arm 17 and extending through the slot in the short end of the toggle lever 29.

As thus far described, the apparatus is not essentially different from that often found in switch mechanisms. To this form of toggle mechanism,

I have added a locking bar 36 for the switch operating lever 27, which look is moved to locking and unlocking positions in response to the movement of lever 29. However, before describing the locking device in detail, it will be helpful to refer briefly to the operation of the toggle mechanism on the assumption that the locking device is not present. Let us assume, therefore, for the present, that the locking bar 36 is omitted and that the switch operating lever 27 of the toggle mechanism is free to move up and down in a manner dependent upon the up and down movement of lever 29 and the resilient connecting link 33. As represented in Fig. 1, the parts are in the switch closing position. To open switch contacts 20 and 21, pin 15 of dial lever 13 slowly rotates beneath roller 19 and moves lever 17 upward.

. Lever arm 29 is moved accordingly, the left end moving downward. Pin 32 moves downward, stretching spring 33, but no appreciable movement of lever arm 27 takes place until pin 32 passes through the neutral position, which is the center line of lever 27. Then the pull of spring 33 is downward on lever 27, and the latter rotates in a clockwise direction. If the parts are properly related, a mild snap action takes place, but owing to the slow movement of lever 29 occasioned by the necessarily slow movement of the timing dial, the snap action is not so energetic as is desired, and there is an appreciable period when the parts are in substantially a neutral or dead center position, and the resulting switch opening operation at contacts 20 and 21 is not so quick and positive as is desired. Instead of pin 26 striking contact arm 21 with considerable force and immediately moving it upward tofull open position, the action is apt to be hesitant, with a more or less gradual decrease in contact pressure and separation of the contacts.

In accordance with my invention, I lock lever 27 in the full switch closing position shown and its operation is delayed until pin 32 has passed through and beyond the neutral position and has nearly reached its extreme downward position and has stretched spring 33 to such an extent that there is a materially greater potential energy available than would be released by the toggle action per se and this energy is now sufficient to snap lever 27 around and strike contact lever 21 a blow that will positively open the contacts instantaneously and at a definite time.

This locking device consists of the bar 36 secured in the slide plate 37, which plate is provided with openings 38 and 39 into which pin 28 and shaft 30 extend and on which the plate slides. The plate is biased towards a locking position by spring 40, and is moved to the unlocking position by the cam surface 41 of shaft 30, against which the square inner surface of opening 39 is held by spring 40. The parts are shown in the locking position, with looking bar 36 under the right end of switch lever 27 blocking downward movement. As lever 29 turns in a counter-clockwise direction due to the lifting of lever 17 by the timing mechshaft 30 is turned and the cam surface 41 slides the plate 37 and with it locking bar 36 to the right, releasing lever 27. The parts are so adjusted that this unlocking action occurs just prior to the maximum upward movement of lever 17 and the corresponding maximum counterclockwise movement of lever 29, at which time the spring 33 has been stretched and built up a maximum operating force for lever 27. The same locking mechanism serves to lock lever 27 in the full switch open position after being moved thereto until the time dial pin 16 comes around and lowers lever 17 and rotates lever 29 to substantially their extreme positions in opposite directions from those described above. Consequently, the switch closing operation is likewise positive and quick. Stops 42 and 43 are provided to limit the up and down movements of switch operating lever 27, and these stops, as well as the locking bar 36, are preferably integral with the sliding plate 37 to secure and maintain the proper relative positions of the parts with respect to each other. After lever 17 has been raised or lowered to extreme positions by pins 15 and 16 and the switch operation has been completed, these pins rotate from beneath the roller 19, and the lever 17 together with lever 29 come back slightly from their extreme positions due to the tension in spring 33. Lever 29 thus comes back towards a central position far enough to again lock lever 27. The switch operating lever 27 is locked in one position or the other most of the time, and is only unlocked for a short period at and following a switching operation. Thus, a complete switching operation caused by a pin 15 passing roller 19 includes (1) placing lever 27 under tension maximum of spring 33, (2) releasing this lever and allowing it to snap over to the other extreme position, and (3) looking it in this new position.

In addition to the more positive opening and closing of the contacts brought about by my looking and unlocking device, the invention is advantageous from the standpoint of more accurate setting of the time switch. In the device without the locking feature, wear of the contacts or the presence of vibration will tend to vary the actual time of switch opening and closing somewhat from that for which the levers on the timing dial are set. When the locking feature is provided, the switch lever is positively locked until a predetermined time, and wear of the contacts has no effect; nor can the contacts be jarred open or closed at approximately the time they would operate if the locking feature were omitted.

In constructing this device for commercial use the parts are more compactly assembled than as shown in the illustration.

I have described a preferred embodiment of my invention as applied to a time switch, but I do not wish to limit the invention to this one embodiment and use. It will be evident that the details of construction of the invention may be modified considerably, and that its use is not confined to a time switch, and I therefore desire a corresponding liberal interpretation of the appended claims.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A toggle mechanism for converting slow oscillatory movement into sudden oscillatory movement, comprising a first lever pivoted on an axis to oscillate back and forth between two extreme positions, driving means for slowly moving said lever from one position to the other, a second lever pivoted on an axis parallel to the first mentioned axis to oscillate back and forth between two extreme positions, a resilient lost motion connection between said levers, the relative disposition of said levers and their connection being such as to form a toggle connection by means of which the second lever tends to follow the movement of the first between their respective extreme positions, a single locking device for the second lever holding it in either of its extreme positions while the first lever is slowly moving from one of its positions to the other, and unitary means responsive to the movement of the first lever as it approaches either of its extreme positions for withdrawing said locking device from looking position and allowing the second lever to suddenly follow the first.

2. A toggle mechanism comprising first and second levers pivoted on different axes parallel to each other, said levers being joined by a resilient lost motion toggle connection, means for oscillating the first lever past the second lever in opposite directions, thereby creating a tension in the resilient connection sufiicient in magnitude and in a direction to cause the second lever to follow the first lever, single locking means for preventing following movement of the second lever in either direction of movement until the first lever has moved a sufiicient distance beyond the second to build up a materially greater tension in said resilient connection, and single means responsive to further movement of the first lever in a given direction to release said second lever.

B. A switch operating mechanism comprising a switch operating lever pivoted to oscllate a fraction of a rotation about its axis to effect switch opening and switch closing operations, a

second lever pivoted to oscillate about an axis parallel to the axis of oscillation of the switch operating lever, the second lever being joined to the first lever by a spring, means for slowly oscillating said second lever tending to oscillate the switch operating lever through said spring, unitary locking means for preventing the switch operating lever from following the movement of the second mentioned lever in either direction of oscillation until the spring has been placed under considerable tension, and a cam moved with said second lever for moving the locking means to release the switch operating member as the second lever approaches the extremity of its oscillation in either direction.

4. A switch operating mechanism comprising a pair of levers pivoted on different but parallel axes, and having arms extending towards each other and joined together with a spring to form a toggle mechanism, means for slowly oscillating one of said levers about its axis, locking means biased to a locking position for preventing the other lever from following such oscillations until the spring has been placed under considerable tension, and a cam moved with the slowly oscillating lever for moving said locking member to unlock said other lever as the slowly oscillating lever approaches the extremity of its movement in either direction.

WILLARD E. PORTER.

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