US2426038A - Current responsive switch - Google Patents

Description

Aug. 19, 1947. J. w. MccLAlN CURRENT RESPONSIVE 'swn'ca Filed Jan. 3, 1945 il. lllllllllli 'Humm J Inventor. j JosephW.McCla`ir1, i El His ttcney.

Patented Aug. 19,l 1947 2,426,038 CURRENT RESPONSIVE SWITCH Joseph W. McClain,

New York Schenectady, N. Y., assignor to General Electric Company,

a corporation of Application January 3, 1945, Serial No. 571,140

(Cl. 20G- 116) 8 Claims.

My invention relates to current responsive switches, more particularly to current responsive switches for opening the circuit of a load device, such as an electric motor, in the event of an excessive current in the circuit, and has for its object a reliable and inexpensive switch providing for manual opening of the circuit and for spring opening in response to an excessive current in either of two legs of the circuit.-

In carrying out my invention in one form, I provide a shaft which is connected to a carrier member rotatably mounted on the shaft and normally held in a predetermined position by a latch so that th'e shaft may be moved manually between open and closed circuit positions. An overcenter snap spring mechanism is attached to the end of the shaft to give proper positioning of the shaft when operated. I also provide current responsive means in each of two legs of the circuit to be protected for separately effecting the operation of the latch to release the carrier member, whereupon the` carrier` member and shaft are moved together by spring biasing means to open the circuit.

For a more complete understanding of my invention, reference should be had to the accompanying drawing, Fig. l of which is a front elevation view of a current responsive switch embodying my invention and showing the parts in their switch closed positions; Fig. 2 is a fragmentary view similar to Fig. 1 showing the parts in their manually open position; Fig. 3 is a view similar to Fig. 2 showing the parts in their current responsive open position; while Fig. 4 is an explodedl view in perspective of the device shown in Figs. l-3 inclusive.

Referring to the drawing, in one form of my invention I provide an operating shaft I (Fig. 4) having secured to it a cam 2 provided with an operating portion extending through an aperture 3 in a slider switch operating member 4 made of electrically insulating material. Mounted on the slider member 4 are three bridging contact members 5, 6 and 1 biased upward, as seen in the drawing, by suitable springs. By means oi a suitable handle 8, the shaft I can be turned to move the slider member 4. As shown, the slider member is in its raised vposition with the bridging contacts in engagement with three pairs of stationary contacts 9, I0 and Il. By turning the handle 8 clockwise substantially 90 degrees, the plate 4 is moved downwardly to the dotted line open circuit position in which the bridging contacts are separated from the pairs of stationary contacts.

A snap movement is imparted to the shaft I by means of an overcenter helical compression spring I2 surrounding a link I3 connected through a pivot has a cylindrical portion which extends tightly through a transverse aperture in the shaft I so as to secure the arm I5 rigidly to the shaft, while the lower end of the link I3 cooperates 'with a carrier member I6 which is rotatably mounted on the shaftvi. The end of the arm I5 projecting from the opposite end of the shaft engages a pin I5' (Fig. 4) secured to the carrier member when the switch is closed thereby to limitthe rotation of the shaft I in the switch closed direction, the engaging parts constituting stop means.

By means of a helical spring I1, the carrier member is biased in a clockwise direction about the axis of the shaft I with respect to a stationary support I8, the carrier member being normally held against the bias of the spring I1 in the position shown in Fig. 4 by a latch arm II). On the lower end of the carrier member is a link 20 which is substantially U arms embracing two projections 2i and 22 on the lower end of the carrier member. On the upper ends of the arms of the member 20 are inwardly extending projections which engage the upper edges of the projections 2l and 22 and form pivots whereby the member im is pivoted on the carrier member.y Each of the projections M and 22 is provided with spaced projections 23 and 24 on its lower end which form stops and between which the member 20 is free to move pivotally when the shaft is turned by the handle 8 thereby to reverse the bias of the overcenter spring I3 and-give the shaft a snap movement.'

As seen in Fig, 2, the link Il". is provided with two diverging projections 25 andv 2B which embrace the member 2li, the overcenter spring I2 being conical in shape so as to fit loosely over the two projections. It will be observed that when the handle is turned clockwise from the position shown in Fig. 4, the projections 25 and 26 are moved downward on opposite sides of the member 20, whereby the overcenter spring is compressed. Then when the pivot I4 moves to the left hand side of the' pivot axis of the upper ends of the member 20, the spring gives the member 20 a counterclockwise bias whereby the member 20 snaps to the position shown in Fig. 2 carrying the lower end of the snap spring toward the right hand to a position to the right of a line extending through the pivot I4 and the axis of the shaft I. This suddenly causes the spring I2 to apply a clockwise bias to the shaft whereby I4 with an arm I5. The arm I5 -shaped and with its a stationary projection 26a.

its movement is completed with et smtp action and the switch opened. Counterclcckwise movereverse movement of the parts, the carrier member at iirst being held against counterclockwise rotation by engagement of the projection 22 with In the closed position the end oi link I5 engages the pin I5 to limit the rotation of the shaft in the closed circuit direction.

For effecting movement of the latch I9 upward about its stationary pivot 21 thereby to release the are connected electrically in two of the three circuits controlled by the pairs of switch contacts 9, I9 and 'II, such as the supply lines or conductors for a three phase motor. More specifically, the thermcstatic tube 29 has its upper end secured to a support 39' and its lower end provided with a slot 3| through which extends an arm 32 mounted on a pivot 33 and biased downward i about the pivot by a spring 34 against the lower wall o! the slot 3|. A suitable resistance type electric heater 35 is inserted in the tube 29 and has its terminals at its upper end connected in circuit with one of the pairs of stationary contacts soy that the thermostatic tube 29 is heated in accordance with the current in the circuit o! that pair of contacts.

When the tube 29 is heated, it expands, and since its upper end is secured, its lower end moves downward, thus permitting the spring 34 to move the arm 32 downward until finally in response to a predetermined excessive current in the heater 35, the arm 32 disengages the lower end of a latch 39 mounted on a pivot 31 on the lower end of a release arm 39. When released, the arm 39 is moved by a spring 39 clockwise about its pivot 49 whereby a transversely extending arm 4I carried by it is moved upward, as seen in Fig, 3, to release the lower end of the latch link 42 whose upper end is mounted on a pivot 43 secured to an arm 44. 'I'he arm 44 is in turn secured to the latch I9. Therefore, when the arm 4I moves upward, the lower end of the latch link 42 is free to move to the right hand and upward, the arm 44 being biased counterclockwise, as seen in Fig. 4, by a spring 45.

When the carrier member I9 is thus released by movement of the latch I9, the shaft I is moved clockwise by the spring I1 to its open circuit position. the parts coming to rest in the positions shown in Fig. 3, in which the latch I9 and the parts connected to it and the arm 4I have been i returned or reset to their original positions. This resetting movement is effected by means of a cam secured to the shaft I having diametricaliy opposite projections 4G and 41. When the shaft I turns, the projection 46 engages the electrically insulating arm 49, thereby returning the release arm 39.to its original position, while the end of the arm 4I pushes downward on the link 42 to return the latch I9 to its latching position. It will be observed that the latch link 42 is U-shaped and its lower base portion is widened and transversely arcuate so that when the arm 4I is moved upward, this base portion4 49, while free to move upward suiiiciently to move the latch arm I9 to a released position, is still in engagement with the arm 4I whereby when the arm 4I is reset, the link 42 is moved downward again. Thereafter when the thermostat 29 cools and moves the arm 32 upward, the arm 39 is again secured.

It win be understood that the 'thermostat 2a and the parts operated and controlled by it are identical with those just described in connection with the thermostat 29, an electrically insulating arm 59 being provided which is engaged by the cam projection 41 for resetting of these parts in the event that the thermostat 29 is heated to open the switch.

The pivoted member 39 is biased to the position shown against the lower end of the arm 39 by a spring 5I. This member 39 is movable clockwise about its pivot against the force of this spring to provide for resetting movement of the arm 39 in the event that the thermostat 29 has cooled and lifted the arm .32 into the path of the member 39.

With the switch in its electrically open position of Fig. 3, when the shaft I is turned counterclockwise to close the switch, the carrier member I6 is rotated with the shaft back into latching engagement with the latch I9. A spring biased latching member 52 on the upper end o! the carrier member moves clockwise with respect to the carriage upon engagement with the end of the latch I9 and slips by the end of the latch I9 back `to the position shown in Fig. 4. 'I'he Darts are now in the positions shown in Fig. 4 'with the switch closed.

While I have shown a particular embodiment of my invention, it will be understood, of course, that I do not wish to be limited thereto since many modiiications may be made, and I therefore contemplate by the appended claims to cover any such modiiications as fall within the true spirit and scope of my invention.

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

1. 'A switch comprising cooperating switch contacts at least one of which is movable, a rotatably mounted operating member an operating connection between said operatingmember and said movable contact. a carrier member mounted for rotation, current responsive means for holding said carrier member in a predetermined angular position, spring means independent of said operating connection for connecting said operating member to said carrier member for biasing said operating member to a closed circuit position, connections connecting said current responsive means in circuit with said contacts for effecting the release of said carrier member in response to a predetermined current in said contacts, and a second spring means for turning said carrier member and thereby turning said operating member through said iirst spring means to its open circuit position. A

2. A switch comprising cooperating switch contacts at least one of which is movable, a rotatably mounted operating mem-ber connected to move said movable contact between open and closed circuit positions when said operating member is turned between two angular positions, said movable contact being moved to its open circuit position when said operating member is turned in a predetermined direction, a carrier member mounted i'or rotation substantially about the axis of said operating member, a ilrst spring means biasing said carrier member for rotation ing member in an opposite direction to its closed circuit position, and connections connecting said current responsive means in circuit with said contacts for eifecting the release of said carrier member in response to a predetermined current in said contacts whereupon said carrier member is turned by said first spring means thereby to turn said operating member in said predetermined direction to its open circuit position.

3. A switch comprising cooperating switch contacts at least one of which is movable, a shaft connected to move said movable contact between open and closed circuit positions when the shaft is turned between two angular positions, said movable contact being moved to its open circuit position when said shaft is turned in a predetermined direction, a carrier member rotatably mounted on said shaft, a rst spring means biasing said carrier member for rotation in said predetermined direction, releasable means for holding said carrier member in a predetermined angular position against the force of said rst spring means, a second spring means connecting said shaft to said carrier member so that when y said carrier member is held by said latch said second spring means causes said shaft to turn in an opposite direction for movement of said movable contact to its closed circuit position, and current responsive means connected in circuit with said contacts for effecting operation of said releasable means to release said carrier member in response to a predetermined vcurrent in said contacts whereupon said carrier member is turned by said first spring thereby to turn said shaft in said predetermined direction and move said movable contact to its open circuit position.

4. A switch comprising cooperating switch contacts at least one of which is movable, a shaft connected to said movable contact for moving said movable contact between open and closed circuit positions when the shaft is turned between two angular positions, said movable contact being moved to its open circuit position when said shaft is turned in a predetermined direction, a carrier member rotatably mounted on said shaft, a first spring biasing said carrier member for rotation in said predetermined direction, a latch for holding said carrier member in a predetermined angular position against the force of said first spring, overcenter snap spring meansconnecting said shaft to said carrier member so that when said carrier member is held by said latch said snap spring means causes said shaft to turn in an opposite direction for snap movement of said movable contact to its closed circuit position, and current responsive means connected in cir.. cuit with said contacts for effecting movement of said latch to release said carrier member in response to a predetermined current in said contacts whereupon said carrier member is turned by said first spring thereby to turn said shaft in said predetermined direction and move said movable contact to its open circuit position.

5. A switch comprising cooperating contacts at turned in a predetermined direction, a carrier member rotatably mounted on said shaft, a first spring biasing said carrier member for rotation in said predetermined direction, means for holding normally said carrier member against rotation in each direction while said shaft is turned to operate said movable contact, said means including a latch for holding said carrier member against movement in at least said predetermined direction by said first spring, overcenter snap spring means connecting said shaft to said carrier mem-perror causing said shaft to turn in each direction with a snap action for snap movement of said movable contact, cooperating stop means on said shaft and said carrier member for limiting the rotation of said shaft in its circuit closing direction relative to said carrier member, and current responsivemeans connected in circuit with said contacts for effecting movement of said latch to release said carrier member for movement in said predetermined direction in response to a predetermined current in said contacts whereupon said carrier member is turned by said lrst spring thereby to turn said shaft insaid predetermined direction and move said movable contact to its open circuit position.

6. A switch comprising two pairs of cooperating switch contacts at least one contact of each pair being movable, a shaft connected to said movable contacts for moving said contacts between open and closed circuit positions when the shaft is turned between two positions, a carrier member rotatably mounted on said shaft, a spring biasing said carrier member for rotation in a predetermined direction, releasable means for holding said carrier member in a predetermined angular position against the bias of said spring, snap spring means connecting said carrier member and said shaft so that when said carrier member is held by said releasable means, said snap spring means causes said shaft to move between said two positions with a snap action for snap opening and closing movement of said movable contacts, and twotemperature responsive devices connected respectively in circuit with said pairs of contacts for securing normally said releasable means in a position to hold said carrier, said releasable means being released by ,movement of either of said temperature responsive devices in response lto a predetermined maxpositions, a carrier member rotatably mounted on said shaft, a spring biasing said carrier member for rotation in a predetermined direction, means for holding said carrier member in a predetermined angular position including a latch for holding said carrier member against the bias of said spring, overcenter snap spring means connecting said shaft to said carrier member so that when said carrier member is held by said latch, said snap spring means causes said' shaft to move in an opposite direction with a snap action for snap closing movement of said movable contacts, a spring for biasing said latch to a position in which said carrier member is released for movement by said first spring whereby said shaft is turned to move said contacts to their open circuit positions, two temperature responsive devices connected respectively in circuit with said pairs of contacts for securing normally said latch in a position in which said latch holds said carrier member, said latch being released by movement of either ofv said temperature responsiveI devices in responseto de predetermined maximum current in said switch whereupon said latch moves in accordance with its spring bias to release said carrier member.

'8. A switch comprising two pairs of cooperating switch contacts, at least one contact of each pair being movable, a shaft connected to said movable contacts for moving said movable contacts between open and closed circuit positions when the shaft is turned between two angular positions, said movable contacts being moved to their open circuit positions when said shaft is turned in a predetermined direction, acarrier member rotatably mounted on said shaft, a first spring i biasing said carrier member for rotation .in said predetermined direction, means for holding normally saidfcarrier member againstv rotation in each direction while said shaft is turned to' operate said movable contacts, said means including a latch for holding said carrier member against movement in at least said predetermined direction by said first spring, overcenter snap spring means connecting said shaft to said carrier member for causing said shaft to turn in each direction with a snap action for 'snap movement of said movable contacts, cooperating stop means on said shaft and said carrier member for 1 mounted on the end of said arm, two temperature responsive devices connected respectively in circuit with said pairs of contacts for securing normally said latch linkin a position in which said latch holds said carrier member, said latch link .being released by movement of either of said temperature responsive devices in response to a predetermined maximum current in its pair of contacts for release of said carrier member and rotation of said carrier member and said shaft to their open circuit positions.

JOSEPH W. McCLAIN.

' REFERENCES CITED The following references are of record in the -le of this patent:

I STATES* PATENTS Number Name Date r 1,885,246 Forman Nov. 1, 1932 2,315,633 May Apr. 6, 1942

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