US2829214A - Electric switch - Google Patents

Description

April 1, 1953 I E. T. PLATZ I 2,829,214

ELECTRIC SWITCH Filed March 24, 1954 INVENTOR.

fizz/444 7: 7/457.

6' Trek/V114 ELECTRIC swrrcn Elwood T. Platz, Detroit, Mich., assignor, by mesne assignments, to I-T-E Circuit Breaker Company, Philadelphia, Pa, a corporation of Pennsylvania Application March 24, 1954, Serial No. 418,278

7 Claims. (Cl. 200-67) This invention relates generally to electric switches, and specifically to those used for the control and distribution of low voltage electric power.

In switches it has long been a problem to obtain contact pressure while the switch is being operated from the closed circuit to the open circuit position. Heretofore rapid separation of the contacts upon circuit opening and rapid closing of the contacts upon circuit closing movement, known in the art as quick break and quick make, respectively, have usually been accomplished by some sort of overcenter spring mechanism. Such mechanism has the disadvantage that contact pressure is greatly reduced as the switch mechanism passes through the dead center position to the quick-break circuit open position. Lack of contact pressure prior to the quick-break point, among other things, promotes the formation of arcs, thereby speeding deterioration of the switch contacts.

Many problems have been encountered because of the need for some means to minimize arcing between contact surfaces immediately prior to closing and subsequent to initial separation of the contacts. Auxiliary arcing contacts and other devices for deflecting the are have proven cumbersome in operation, difficult in maintenance and expensive to manufacture.

Accordingly, a principal object of this invention is to provide a novel switch having rapid closing of the contacts upon circuit closing movement and rapid separation of the contacts on circuit opening movement.

Another object of this invention is to provide a switch in which contact pressure is maintained during the circuit opening movement.

Another object of this invention is to provide a switch wherein contact pressure is increased as the switch mechanism is moved to the open circuit position.

Another object of this invention is to provide a switch mechanism which affords maximum contact pressure immediately prior to separation of the contacts.

Another object of this invention is to provide a novel quick-make, quick-break switch mechanism wherein the contacts operate in a wiping movement so that contact surfaces will remain free from nonconductive corrosion at all times.

A further object of this invention is to provide a switch construction which does not require the use of auxiliary arc extinguishing or preventing devices.

Still another object is to provide a switch mechanism of simple construction which is easy and inexpensive to manufacture.

Other objects and purposes will appear generally from the drawings and following description in which:

Fig. 1 is a side elevational view of the switch with a portion of the coverplate removed showing the switch mechanism in the closed circuit position.

Fig. 2 is a side elevational view of the switch with a portion of the coverplate removed showing the switch mechanism in the open circuit position.

nited States Patent ice Referring to Fig. 1, an embodiment of the invention as shown in the closed circuit position includes a rectangularly shaped housing 1 of insulative material having end walls 6 and 6a, a bottom 6b, a rear wall 6c, a slotted top wall 6d, and a removable coverplate 2. A fixed contact 3 comprising a flap strip of electrically conductive metal, such as copper, is firmly mounted in some suitable manner to the end wall 6 of housing 1 with a portion 4 projecting through an opening in the end wall 6. This portion 4 has a terminal screw 5 inserted in a tapped opening to serve as a terminal for the connection of'a lead line conductor. From the opposite end of fixed contact 3, an extension projects downwardly to form a fixed contact are tip 7.

With the switch in the on circuit position, as shown in Fig. 1, a movable contact 8a, comprising a portion of an electrically conductive contactor 8, overlaps and engages the upper surface of fixed contact 3. Extending upwardly from the left end of contactor 8, as viewed in Fig. 1, is a projection 9 to which is secured the biasing mechanism hereinafter described. Extending downwardly from the right end contactor 8 is a projection 10, having connected thereto a flexible electrical conductor 11. Conductor 11 is secured at its opposite end to a load terminal 12 which extends through end wall 6a. A terminal screw 5 is provided for the attachment of the load conductor. A notch 20 is provided in the lower edge of contactor 8 to receive hook 18 of latch member 17, as shown in Figs, 2 and 3.

In the closed circuit position the circuit may be traced from line terminal 5 to fixed contact 3 to movable contact 8a through contactor 8 and flexible conductor 11 to load terminal 12.

To actuate movable contact 8a out of conductive abutment with fixed contact 3, an actuator arm 13 comprising a strip of insulating material is pivotally mounted by a pivot member 15 on rear wall 6c of housing 1 so that its upper end projects through a slot in the top wall 6d of housing 1. The lower end of actuator arm 13 is pivotally connected as by a bolt 16 to contactor 8 so that rotation of actuator arm 13 about pivot member 15 will cause movable contact 8 to slide rectilinearly, as viewed in Figs. 1, 2, and 4, along the upper surface of fixed contact 3. Pivotally mounted on the side of actuatorarm 13, as by a bolt 30, above pivot 15 is a metallic latch member 17. The lower portion of the latter overlies movable contact 8 and terminates in a narrow tip, which is bent inwardly at right angles to form a hook 18, as shown in Fig. 1. A tension spring 31, secured at one end to a pin 19 in the rear wall 60 of housing 1 and at the other end to the lower portion of latch 17, urges latch 17 clockwise, as viewed in Figs. 1, 2, and 4, about bolt 30. Hook 1% of latch member 17 is thus constantly biased against the lower edge of contactor 8 and into engagement with notch 20 when the switch is moved to the oii circuit position of Fig. 2.

To provide contact pressure and also opening and head 24. This head 24; receives projection 9 of con tactor 8. Head 24 is pivotally linked to extension 9 by a bolt 26. The slotted end of strip 23 receives pin 2'7, which projects from the rear wall 60 of housing 1.

Patented Apr. 1, 1958 Strip 23 is movable both pivotally and reciprocally relative to pin 27 in accordance with the motion of contactor 8 when the switch is operated. Coiled about the body of strip 23 is a compression spring 28, the upper end of which is fixedly retained by pin 27. The lowerend of spring 28 rests against the enlarged head 24 of strip 23. The compressive force of the spring 28 biases the contactor 8 and, therefore, movable contact 8a into conductive abutment with fixed contact 3 when the switch mechanism is moved to the closed circuit position shown in Fig. 1.

In order to safeguard movable contact 8a of contactor 8 and. the bottom 6a. of housing 1 from excessive wear due to the snap opening movement, asupport member 29 may be, provided. The location of this. support 29 is such that contactor 8 rests upon it at the completion of the open circuit movement providing clearance between the contact 8a and the bottom 6a of housing 1, as shown. in Fig. 2. Pins 33v and 34 project from the rear wall 6c of housing 1 to provide limit stops for actuator arm 13 in the open and closed circuit positions, respectively.

To move. the switch to the. open circuit position from the closed circuit position of Fig. 1, actuator arm 13 is manually rotated counterclockwise about pivot member 15. Contactor 8, which is pivotally linked with actuator arm 13 at 16, thus rectilinearly withdraws contact from conductive abutment with fixed contact. 3. At the same time spring 28 is compressively loaded. When contact 8a clears the end of fixed contact 3, the bias of spring 28 will rotate contactor 8 counterclockwise in a quick-break movement until it strikes support 29. Further rotation of the actuator arm 13 reduces distance between the pivot 30 of latch 17 and the point of contact of hook 18 of latch 17 on the bottom edge of contactor 8. Latch 17, urged by tension spring 31, will rotate clockwise simultaneously with the withdrawal of contact 8a from fixed contact 3 until hook 18 has engaged notch 20 in bottom surface of movable contact 8, as shown in Figs. 2 and 3. At this point the switch mechanism is in the off circuit position.

Arcing between movable contact 8a and fixed contact 3 will commence when movable contact 8a has been fully separated from conductive abutment with fixed contact 3. The path of the, arc will be from movable contact 8a to the outermost edge of the fixed contact 3. As contactor 8 rotates and moves downwardly and contact 8a moves away from fixed contact 3, the path of the are, due to its tendency to remain as short as pos sible, will shift so that the contact point of its path on movable contact 8 will move upwardly along the end of contactor 8, and the contact point on fixed contact 3 of the arc will move downwardly along the vertical extension 7 of fixed contact 3. As the distance between extension 7 and contactor 8' increases, the arc is stretched until it is severed. The deflection and control of the arc in this manner avoids pitting of the contact surfaces, in sures. clean contact surfaces at all times, thus greatly prolonging the life of the contacts.

To move the switch to the closed circuit position, the upper end of actuator arm 13is manually rotated clockwise about pivot member 15. As arm 13 is rotated, latch 17' is pulled upwardly, thus raising contactor 8 through engagement of hook 18 with notch 20. Slotted strip 23 moves upwardly under the control of pin 27, compressing spring 28. Further upward movement of latch 17 and contactor 8 brings latch 17 into contact with pin 32. The switch mechanism is then in the position shown in Fig. 4. Upon continued movement of actuator arm 13', the hook 18 of latch 17 is forced downwardly and to the right, as viewed in Fig. 4, against the force of spring 31 out of engagement with notch 20. As hook 18 clears notch 20, contactor 8 is instantaneously released and moves to the left and downwardly. bringing movable contact 8a into engagement with fixed contact 3. Latch 17 is biased to the right to the position shown in Fig. l by the engagement of hook 18 with the lower edge of contactor 8a. Spring 31 is thus loaded for the next actuation of the switch to the open circuit position.

From the foregoing description it can be seen that a novel, simple switch structure is provided by which instantaneous separation and closing of the switch contacts is obtained. Contact pressure is increased prior to separation of the contacts, and arcing is held to a minimum.

Having thus described my invention, I claim:

1. An electric switch including a casing, a fixed contact disposed in said casing, an electrically conductive contactor having a movable contact engageable with said fixed contact, resilient means biasing said contactor to engage said movable contact with said fixed contact upon operation of said switch to the closed circuit position and to disengage from said fixed contact when said switch is operated to the open circuit position, a manu ally operable actuator secured to, said contactor to slidably withdraw said movable contact from said fixed .contact, and a latch member secured to said actuator and engageable withv said contactor upon operation of said switch to. open circuit position; said latch member operatively connectable to displace said contactor upon initial operation of said actuator toward the engaged position and disengageable from said contactor to permit said movable contact to move rapidly into engagement with said fixed contact.

2. An electric switch including a casing, a fixed con tact disposed in said casing, a contactor including a movable contact engageable with said fixed contact when said switch is actuated to the closed circuit position and disengageable from said fixed contact when said switch is moved to the open circuit position, an actuator secured to said contactor for initiating operation of said switch to the closed circuit position from open circuit position and to open circuit position from closed circuit position, means secured to said contactor to provide circuit opening and closing force, a member secured to said actuator and engageable with said contactor to cooperate with said actuator in moving said movable contact into engagement with said fixed contact, and, means secured in said casing for disengaging said memberfrom said contactor to permit said fixed and movable contacts to close instantaneously.

3. In an electric switch mechanism a fixed contact, actuating means comprising a handle pivotally mounted in a casing enclosing said mechanism, a contactor pivotally secured to said handle and having a movable contact secured thereto, a latch pivotally mounted on such handle, said latch engaging a notch in said contactor when said switch is opened and thereafter operatively connected to move said contactor and said movable contact toward said closed circuit position, means to dis engage said latch from said notch to release said contactor and said movable contact, resilient means urging said contactor to cause said movable contact to snap into engagement with said fixedcontact, said resilient means also urging said contactor to cause said movable contact to disengage from said fixed contact.

4. An electric switch being comprised of a fixed contact, a movable contact, an actuator, and a biasing means; said movable contact having an engaged and disengaged position with respect to said fixed contact; said actuator being mounted on a fixed pivot and being selectively movable to a first and a second position; said fixed contact being pivotally mounted on said handle at a point removed from said fixed pivot; said biasing means operatively connectedto-said movable contact and having a component of force to maintain said movable contact in said engaged position when said actuator is in said first position and while said" handle is being moved a portion of the distance from said first to said second position; said biasing-means urging said movable contact into said disengaged position while said handle is being moved from said first to said second position by exerting a force on said movable contact in the same direction as said component of force.

5. An electric switch being comprised of a fixed contact, a movable contact, an actuator, and a biasing means; said movable contact having an engaged and disengaged position with respect to said fixed contact; said actuator being mounted on a fixed pivot and being selectively movable to a first and a second position; said fixed contact being pivotally mounted on said handle at a point removed from said fixed pivot; said biasing means operatively connected to said movable contact and having a component of force to maintain said movable contact in said engaged position when said actuator is in said first position and while said handle is being moved a portion of the distance from said first to said second position; said biasing means urging said movable contact into said disengaged position while said handle is being moved from said first to said second position by exerting a force on said movable contact in the same direction as said component of force; said movable contact being operatively positioned and controlled by said actuator to have rectilinear motion in moving from said engaged to disengaged position; said movable contact maintained in high pressure engagement until the precise moment of disengagement when said actuator is being moved from said first to said second position.

6. An electric switch being comprised of a fixed contact, a movable contact, an actuator, and a biasing means; said movable contact having an engaged and disengaged position with respect to said fixed contact; said actuator being mounted on a fixed pivot and being selectively movable to a first and a second position; said fixed contact being pivotally mounted on said handle at a point removed from said fixed pivot; said biasing means operatively connected to said movable contact and having a component of force to maintain said movable contact in said engaged position When said actuator is in said first position and while said handle is being moved a portion of the distance from said first to said second position; said biasing means urging said movable contact into said disengaged position while said handle is being moved from said first to said second position by exerting a force on said movable contact in the same direction as said component of force; said movable contact being operatively positioned and controlled by said actuator to have rectilinear motion in moving from said engaged to disengaged position; said movable contact maintained in high pressure engagement until the precise moment of disengagement when said actuator is being moved from said first to said second position; said movable contact being repositioned with respect to said stationary contact to thereby release energy stored in said biasing means to efiect said disengagement with snap-action.

7. An electric switch being comprised of a fixed contact, a movable contact, an actuator, and a biasing means; said movable contact having an engaged and disengaged position with respect to said fixed contact; said actuator being mounted on a fixed pivot and being selectively movable to a first and a second position; said fixed contact being pivotally mounted on said handle at a point removed from said fixed pivot; said biasing means opcratively connected to said movable contact and having a component of force to maintain said movable contact in said engaged position when said actuator is in said first position and while said handle is being moved a portion of the distance from said first to said second position; said biasing means urging said movable contact into said disengaged position while said handle is being moved from said first to said second position by exerting a force on said movable contact in the same direction as said component of force; said movable contact being operatively positioned and controlled by said actuator to have rectilinear motion in moving from said engaged to disengaged position; said movable contact maintained in high pressure engagement until the precise moment of disengagement when said actuator is being moved from said first to said second position; said movable contact being repositioned with respect to said stationary contact to thereby release energy stored in said biasing means to effect said disengagement with snapaction; a latch member secured to said actuator and operatively engageable with said movable contact to displace said movable contact upon initial operation of said actuator from said second to said first position, and means operatively connected to said latch member for disengaging said latch member from its said operative connection with said movable contact to permit said movable contact to engage said fixed contact with a snap-action.

References Cited in the file of this patent UNITED STATES PATENTS 1,518,701 Penn Dec. 9, 1924 2,174,232 Baker Sept. 26, 1939 2,204,393 Atwood June 11, 1940 2,473,848 Baxter June 21, 1949 2,514,839 Caswell July 11, 1950 2,533,743 Sharp Dec. 12, 1950 FOREIGN PATENTS 563,235 Great Britain Aug. 3, 1944

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