US1738406A - Electric switch and operating means therefor - Google Patents

Description

' Dec. 3, 1929. G. R. TOWNSEND 1,738,406

ELECTRIC SWITCH AND OPERATING MEANS THEREFOR Filed June 18, 1925 Fig.9.

Inven'lior- George R.Townsend His Attorngg Patented Dec. 3, 1929 UNITED STATES PATENT OFFICE GEORGE R. TOWNSEND, OI? SCHENECTADY, NEW YORK, ASSIGNOR T GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK ELEGTRIQ SWITCH, AND OPERATING MEANS THEREFOR Application filed June 18,

My invention relates to improvements in electric switches, and in particular to improvements in the operating means whereby the switch contact mechanism is quickly opcrated to and from its definite positions, as

for example to and from the closed position of the switch. It is desirable that the movement of the contact mechanism be very quickly accom- W plished both in opening and in closing an electric circuit since destructive arcing at the switch contacts is thus.eitherminimized or entirely prevented. It is also desirable that after an operator has begun the opening or closing movement of the switch handle and has proceeded with the movement up to a certain position that the movement of the switch contact mechanism shall not commence until the handle has been moved to the certain position, whereupon the quick movement of the contact mechanism begins and the contact mechanism proceeds to its definite position regardless of further movement of the handle in the same direction. Pitting of the contact mechanism due to a slow movement of the handle is thus avoided since the speed of operation of the contact mechanism is entirely independent of the speed of operation of the switch handle. A

Quick action operating means for electric switches as ordinarily constructed have heretofore provided some sort of a resilient conncction such as a spring between the switch operating member and the switch contact mechanism so as to obtain a quick closing and a quick opening of the switch. In such of that type of switches with which I am familiar, in case the spring breaks or is rendered otherwise inoperative, the switch cannot be operated and that is objectionable, particularly when the switch is employed for controlling electric motors.

One of the objects of the invention is the provision of an improved quick action operating means for electric switches, whereby in case of failure of the part of the operating mechanism which effects the quick action feature, the switch may nevertheless be operated at will so that the circuit controlled by the switch may be opened and closed and 1925. Serial No. 38,075.

otherwise governed although not with the desired snap action.

The present invention is particularly applicable to switches required to control substantial amounts of power such as motor starting switches and the like. In such switches ruggedness of .construction is particularly important because of the severity of the service to which such switches are ordinarily subjected, and simplicity of construction and arrangement is also of great importance in order to obtain the desired reliability of operation and the necessary economies for large scale production.

In the embodiment of my invention which I now regard as the preferred form, I provide an improved, simple, rugged and reliable quick action operating means between the switch handle and the switch contact mechanism whereby the above mentioned features to be desired in switches of this class are ob-\. tained. Among other features of the invention there is provided an oscillating member which is connected to the switch contact v mechanism and is connected to an operating member through a spring which is put under strain during the initial movement of the operating member and the strain thereof is released to move the oscillating member and the contact mechanism quickly during so the final movement of the operating member. The arrangement is such that in case the spring breaks, or is otherwise rendered inoperative, the oscillating member will be operated by the operative member so that the switch. is fully operating although without the quick action feature.

For a better understanding of the invention, reference is had to the accompanying drawing in which Fig. 1 represents an electric switch in accordance with the invention, the parts of the switch being in their respective positions when the switch contact mechanism is in the open position. In Fig. 2 the various parts of the switch are shown in their respective positions when the switch contact mechanism is in the closed position. Fig. 3 is a very simplified diagram of a motor control system employing the electric switch of the invention for connecting and disconnectin the electric motor to a source of supply. lteferring to the drawings, the switch contact mechanism comprises a pair of movable switch contacts 10 which are adapted to cooperate with corresponding stationary contacts 11. The contacts 10 are mounted on and operated by the shaft 12 of insulating material. The shaft 12 is connected to the oscillating member 13 so as to be operated thereby, by means of a forked member 14 secured to the shaft 12 and a pin 15 which is secured to the oscillating member 13 and is arranged to cooperate with the prongs of the fork-ended member 14. This oscillating member 13 has its upper end pivotally mounted in the supporting frame 16, and the other end of the oscillating member is connected to the operating member 17 by means of a spring 18 which has one end hooked over the catch 19 on the lower end of the oscillating member and the other end thereof hooked over the pin 20 connected to one arm of the operating member 17.

he pin 20 connects the operating member 17 and the intermediate member 21 which is mounted for rotation about the extension 12 of the shaft on which the switch contact mechanism is mounted. This intermediate operating member 21 is provided with two oppositely disposed arms which are arranged I to engage the oscillating member 13 when the switch is in either of its definite positions, that is, the one arm engages the oscillating member when the switch is in the open positlon as indicated in Fig. 1 and the other arm'engages the oscillating member when the switch is in the closed position as indicated in Fig. 2. The operating member 17 has connected thereto a handle 22 so that the openmg and closing of the switch will be under the control of an operator.

In order to insure that the switch contact mechanism will make positive contact in the closed position and not be affected by the shocks class is ordinarily subjected, the resiliently mounted detent 23 is provided for holding the free end of the oscillating member 13 as shown in Fig. 2 and thus securely locking the switch contact mechanism in the closed positlon. The arrangement of the parts is such that the arm 24 on the operating member 17 .will engage the catch 23 and release the sa he so as to permit the switch contact mechanism to move to the open position after the handle 22 has moved the operating member 17 a predetermined distance in the opening direction.

- Theoscillating member is also arranged to engage the catch 23 and enforce a quick closing of the switch contacts.

As thus constructed'and arranged, the operation of my invention is as follows: With the switch contact mechanism in the open position as indicated in Fig. 1, in order to close the switch, the handle 22 will be pulled and jars to which apparatus of this upwardly, thereby rotating the operating member 17 in the same direction and putting the spring 18 under a strain to close the switch contacts. The arm 24 will release the catch 23 and the catch will move upward under its spring pressure until the projection 25, which has a sloping cam surface, engages with the lower end of the oscillating member 13. The contact mechanism will not immediately move to the closed position since the closing movement will not begin until after the pin 20 carried by the one arm of the operating member 17 has moved past the line connecting the lower or free end of the oscillating member 13, the shaft 12 and the pin 20 and the oscillating member has released itself from engagement with the sloping projection 25. \Vhen the pin 20 has been moved past this dead center position, the strain set up in the spring 18 during the initial movement of the handle 22 will now be effective to overcome the holding effect, of the camshaped projection 25 on the catch 23 and very quickly throw the oscillating member 13 in a counter-clockwise direction about its upper pivotal support in the supporting member 16, thereby moving the contacts 10 very quickly into engagement with the contacts 11 through the forked end member 14 and the pin 15 connected to the oscillating member 13.

The shaft 12 passes through the slot 26 in the lower end of the oscillating member 13, and when the contact mechanism has been moved into the closed position the shaft 12 will be in engagement with the left-hand edge of this slot and thus arrest further movement of the contact mechanism in the closing direction. It will be obvious that the opening movement of the contact mechanism is likewise arrested by the shaft 12 coming into engagement with the right-hand edge of this slot. When the contact mechanism has been thus moved into the closed position, the lower or free end of the oscillating member 13 will be moved to such a position that this free end of the oscillating member is engaged by the projection 27 of the resilient catch 23 so that the switch is securely locked in the closed position and will not be affected by the shocks and jars to which apparatus of this class is ordinarily subjected.

In order to open the switch, the handle 22 is pulled downwardly, thereby again placing the spring 18 under a strain to open the contact mechanism during the initial movement of the handle. As soon as the pin 20 has passed the dead center position with reference to the lower end of the oscillating member and the shaft 12, further movement of the handle 22 will bring the arm 24 of the operating member 17 into engagement with the end of the pivoted catch 23 so that the oscillating member is free to move in the opening direction by reason of the strain set up in the spring 18 during the initial opening moveloo lit)

ment of the handle 22. The parts will now return to their respective positions indicated in Fig. 1.

In Fig. 3 the switchvis indicated as controlling the connection and disconnection of an electric motor 28 from a suitable source of supply: The switch is indicated in very diagrammatic form and the various parts thereof are lettered the same as the corre sponding parts of Figs. 1 and 2.

It will be observed that the switch employs comparatively few parts and that the various parts are of rugged and substantial construction. In the open position of the switch there is no strain on the spring 18 and this is of advantage since the spring is only under strain when the switch is being used to close the controlled circuit. It will also be observed that the respective parts of the switch are relatively simple in construction so that the device lends itself very readily to large scale manufacture. A quick opening and a quick closing of the control circuit is always effected, regardless of the speed at which the operator moves the handle 24. It is impos sible for the operator to leave the handle in an intermediate position such that arcing is established and maintained at the switch contacts. That is because of the fact that during the initial movement of the handle there is no resulting movement of the switch contact mechanism, and as soon as the movement of the switch contact mechanism has started, it is completed regardless of further movement of the handle in the same direction.

In case the spring 18 should break, the switch may nevertheless be operated through theaction of the intermediate member 21. Thus, in closing the switch, moving the handle 22 will also move the intermediate member 21, and after a limited movement thereof the arm 29 will engage the member 13 and move the same so as to close the switch con- 'tacts. Except for the quick action function obtained by reason of the operation of the spring 18, the operation will be the same as previously set forth. In opening, the arm 30 of the intermediate member will engage the oscillating member 13 and cause the switch contacts to be opened, although not with a snap action.

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

1. Operating means for an electric switch having switch contact. mechanism operable between two definite positions, comprising an operating member, an oscillating member connected to said contact mechanism for operating the same between said positions, a spring interposed between said operating member and said oscillating member for imparting a snap action to the contact mechanism in response to movements of the operating member, an intermediate member operated by the operating member for operating the contact mechanism to and from said definite positions in response to movements of the operating member in case offailure of said spring, and a resiliently mounted catch cooperating with said oscillating member for holding the said contact mechanism in one of said positions, the said operating member being arranged to release said catch during the initial movement of the operating member to operate the switch.

Operating means for an electric switch having a shaft and switch contact mechanism mounted thereon and operable between an open position and a closed position, comprising a pivoted operating member, a pivotally mounted oscillating member connected to said contact mechanism for operating the same between said positions, the said oscillating member being mounted to move about a different pivot than said operating member, a spring interposed between the free end of said oscillating member and said operating member, the said spring being relieved of strain in the open position of the switch and put under strain during each movement of the operating member to open and close the switchto eifect. a snap action in opening and closing the switch, and an intermediate member operated by said oper-. ating member for operating said oscillating member and said switch contact mechanism in case of failure of said spring.

3. Operating means for an electric switch operable between two definite positions, comprising a pivotally mounted operating member, a pivotally mounted oscillating member connected to said contact mechanism for operating the same between said positions, the said oscillating member being mounted to move about a different pivot than said opcrating member, a spring interposed between the free end of said oscillating member and said operating member, the said spring being put understrain during each movement of the point of connection of the spring with said operating member toward the line connecting the centers of movement of said members and released to operate the said oscillating member and move the contact mechanisnfi to one of its definite positions during the move- 'ment of the operating member past the said centers of movement, means operated by said operating member coacting with said contact mechanism for operating said mechanism to and from said positions in case of failure of said spring, and a resiliently mounted catch cooperating with said oscillating member for holding the said contact mechanism in one of said positions, the said operating member being arranged to release said catch during the initial movement of the operating member to operate the switch.

4. Operating means for an electric switch having a shaft and switch contact mechanism mounted thereon and operable between leased to operate ed rotation about the axis of said an open position and a closed position, comprising an operating member mounted for limited rotation about the axis of the switch shaft, an oscillating member mounted to move about a pivot spaced apart from the switch shaft, the said oscillating member having a slot therein through which the switch shaft passes so that the movement of the oscillating member about said pivot is limited by the switch shaft, a spring interposed between the free end of said oscillating member and said operating member, the said spring being put under strain during each movement of the point of connection of the spring with said operating member toward the line connecting the said pivot and the axis of said shaft and released to operate the said oscillating memher and move said contact mechanism from one of said positions to the other during movement of said point of connection of the spring with the operating member past the said line.

5. Operating means for an electric switch having a shaft and switch contact mechanism mounted thereon and operable between an open position and a closed position, comprising an operating member mounted for limited rotation about the axis of said shaft, an oscillating member mounted to move abouta pivot spaced apart from the switch shaft, the said oscillating member having a slot therein through which the switch shaft passes so that the movement of the oscillating member about said pivot is limited by the switch shaft, a spring interposed between the free end of said oscillating member and said operating member, the said spring being put under strain during each movement of the point of connection of the spring with said operating member toward the line connecting the said pivot and the axis of said shaft and rethe said oscillating member and move said contact mechanism from one of said positions to the other during movement of said point of connection of the spring with the operating member past the said line, and means operated by said operating member and coaeting with said oscillating member to operate said mechanism to and from said positions in case of failure of said spring.

6. Operating means for an electric switch having a shaft and switch contact mechanism mounted thereon. and operable between an open position and a closed position, comprising an operating member mounted for limit shaft, an oscillating member mounted to move about a pivot spaced apart from the switch shaft,

the said oscillating member having a slot therein through which the switch shaft passes so that the movement of the oscillating member about said pivot is limited by the switch shaft, a spring interposed between the free end of said oscillating member and said operating member, the said spring being put under strain during each movement of the point of connection of the spring with said operating member toward the line connecting the said pivot and the axis of said shaft and released to operate the said oscillating member and move said contact mechanism from one of said positions to the other during movementof said point of connection of the spring with the operating member past the said line, and

-means operated by said operating member

Images