US2068582A - Electric switch - Google Patents

Description

Jail. 19, 1937. F. c. VON HOORN ELECTRIC SWITCH Filed may 1, 1934 w u |H w mn n .O 3 W m 3 aw Patented Jan. 19, I 1937 STATES ELECTRIC SWITCH Fred G. von Hoorn, Bridgeport, Conn., assignor to General Electric Company, a corporation of New York Application May 1, 1934, Serial No. 723,313 Claims. (c1. zoo-15c) My invention relates to electric switches and more particularly to movable switch contacts. In rotary switches of the type used on electric ranges the conditions under which the switches 5 operate are relatively severe because of the heavy load currents and because of the frequency of operation of the switch. The life of a-switch as a general proposition has been no greater than the life of any one of its component parts. This is true because of the fact that the switches when made sufliciently rugged to withstand the hard usage could most conveniently be made so that it was impossible to repair the switch and that upon the breakage of any part the switch as a whole had to be replaced. Quite frequently the cause of breakdown of a switch has been the breakage of the switch operating mechanism or a part of the movable switch element. The most common single cause of the failure of the switch to operate has been burning of the switch contacts especially one of the movable switch con- I tacts. The source of damage to the switch contacts is the are drawn on the making and breaking of the circuit which pits the contact surface and ultimately causes the contacts to stick or the resultant heating at the contacts will remove the spring tension from the movable contact and thus cause it to assume a permanent set in a position in which it will not engage a stationary contact. Also, in order to provide the necessary contact pressure upon engagement of the movable contact with the stationary con tact it is necessary for some movement or give of one of the contacts against its inherent spring tension. The repeated flexing of the contact which is generally' the movable contact may cause its breakage.

The object of my invention is to provide an improved switch contact for electric switches which may be manufactured at a relatively low cost, is easily secured in position in the switch, may be replaced upon its breakage or for any cause without the necessity of replacing the switch as a whole and which will automatically [5 center itself with respect to the stationary contact upon engagement of the stationary contact.

What I consider to be novel and my invention element; Fig. 3 is a perspective view of the switch contact and its securing means; Fig. 4 is a side sectional view of part of the switch of Fig. 1 showing an end view of the switch contact in engagement with the stationary contacts and Figs. 5 and 6 are detail views of a modified form of switch contact. The switch shown in Fig. 1 is substantially the same as that shown in Kempton Patent No. 1,919,949 which is assigned to the same assignee as the present invention. A stationary member to is provided to which is secured contacts II which may be connected to a supply circuit through the intermediary of binding posts l2. Other stationary contacts l3 are provided partly hidden by rotor [4 but are better illustrated in Fig. 4. Contacts I3 are spaced radially from contacts II and are adapted to be connected to the load circuit by means of binding posts l5. To interconnect contacts II and 13, bridging contacts I6 are provided and secured to rotor l4. As better indicated in Figs. 2, 3, and 4, bridging contact I6 is formed from a flat strip of metal, preferably phosphor bronze, into a substantial U-shape. Contact surfaces H are provided at each of the free ends of the U and formed in arcuate cross section to conform to the shape of the stationary contacts H and I3 and also to provide an entering wedge for the contact l6 when moving into engagement with the stationary contact. Contacts [6 are secured in slots I8 provided in rotor [4 by means of compressible cotterpins [9 which pass under the top of the U and engage the top of rotor l4. Integral transverse projections 20 are pro-, vided on contact [6 which seat in grooves 2| provided in rotor 14. It may be desirable to use other securing means than the compressible cotterpin l9 such as by the provision of the projections from the top of the U of contact "5 which may be turned down after the contact is inserted into slot I8 from the bottom. As best indicated in Fig. 4, the means of securing the contact IS in rotor Hand the clearance on each side of the contact permits relative transverse movement of the contact I6 upon its engagement with stationary contacts II and 13. This feature is important because it makes it unnecessary to carefully align slot l8 and contact 16 with the center line of contacts II and I3. Thus the contact l6 automatically centers itself upon engagement of the stationary contacts II and I3. Also, it has been found that the contact l6 has a greater life than because of its relatively free transverse movement which thus reduces the strain on the contacts which may result from slight inaccuracies in the centering of the stationary movable contacts with respect to each other. Contact it may readily be replaced if its contact surfaces H are pitted or damaged or the contact broken merely by the removal of cotterpin i9 and the substitution of a new contact it. As pointed out above, the possibility of replacing the movable contact it eliminates the necessity of replacing the whole switch or the rotor element upon the damage to one of the contacts.

In Figs. 5 and 6 a modified form of movable switch contact 22 is shown. Contact 22 is similar in its general shape to contact 16. Two integral projections 23 and 2d are provided and may be formed by pressing them out from the sides of the U of the contact 22. Projections 23 and 2% extend outwardly fromthe sides of the U and engage shoulders 25 and 26 respectively when the con-' tact is located in rotor it. Two integral projections 21 and 28 are provided from the top of the contact 22 which engage the top wall of rotor i l. By this arrangement contact 22 may be inserted from the top of the rotor and when the contact is forced home to its normal position the projections 23 and 2t spring outwardly into engagement with shoulders 25 and 25 to secure the contact in position. In order to permit removal of contact 22 from the rotor Hi, two longitudinal recesses 29 and 3B are provided to acommodate a tool which may compress the projections 23 and 2% to permit the contact 22 to be drawn upwardly out of recess it. By this arrangement, contact 22 may be inserted and removed while the rotor it is in its normal position with respect to base iii. Thus it makes it unnecessary to remove rotor it for replacement of the movable switch contacts.

Fronr the foregoing it may be seen that an improved switch contact has'been provided which has a relatively low cost of manufacture, has a relatively long life, is easy to assemble to the switch and may be replaced upon injury to the contact without necessitating replacement of any other part of the switch or the switch as a whole.

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

1. In an electric switch, stationary contacts spaced apart, a movable contact of U shape adapted to bridge said stationary contacts, and securing means connected to removably support said movable contact at the top of the U and permit transverse movement of the contact upon engagement with the stationary contacts.

2. In an electric switch, a stationary member, contacts secured to said stationary member, a movable member having spaced slots, contacts of U-shape located in the slots of said movable member, and means to removably secure said last named contacts at the top of the U in said slots to permit free transverse movement of the contacts engagement of the ends of the contacts with the first named contacts.

4. In an electric switch, a stationary member, contacts secured to said member, a rotor having spaced slots, U shaped bridging contacts located in said slots and having integral projections seated in grooves communicating with said slots, and removable securing means for said last named contacts adapted to permit relative transverse movement of the free ends of said bridging contacts.

5. An electric switch comprising a base of in sulating material, stationary contacts secured to said base, a rotor of insulating material, contacts of U-shape adapted to bridge said stationary contacts located in spaced slots in said rotor, and means securing the last named contacts in the slots in said rotor at the top of the U whereby the contacts of U-shape may pivot about the top of the U and adjust themselves to irregularities in the location of the stationary contacts.

FRED G. VON HOQRN.

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