US1121877A - Electric switch. - Google Patents

Description

W. M. SCOTT, J. H. WYATT & T. W. GREATHEAD. ELECTRIC SWITCH. ArPLIoATIoN rxLEn 1120.5, 1912.

1,121,877. atented Dec. 22, 1914.

'HE MORRIS PETERS C0.. PHUTO-LITHU., WASHINGTON, D4 C l "UNiTED sTATEs PATENT oEEioE.

WILILIAIMl M. SCOTT, 0F RADNOR, (JAMES H. WYATT, OF PHILADELPHIA, AND THOMAS W. GREATHEAD, OF MORTON, PENNSYLVANIA, ASSIGN ORS TO WILLIAM M. SCOTT,

f OF RADNOR, PENNSYLVANIA.

ELECTRIC SWITCH.

Specification of Letters Patent.

Patented Dec. 22, 1914.

Application filed December 5, 1912. Serial No. 735,040.

kwhich the following isaspeciication.

Our invention relates to electric switches and particularly `to the type of electric switches involving a brush lor bundle of laminae engaging end-on with a terminal.

It is the object of our invention to provide in such a switchemploying a laminated contact member, a terminal cooperating with the laminee to prevent collection of dust or dirt on or between the lamina: or yupon the terminal.'` l

' To this end we provide a terminal having a slotted contactl face, the dust or dirt whichr may collect being wiped from the contact surfaces of the terminal and prevented from lodging between laminee by being swept into the slot or slots on the terminal. block by the movement over the contacting surface by the end-on engagement and movement of the laminae.

With a terminal having an unslotted contact surface there is a tendency for dust and dirt to pack in between the laminae and ultimately interfere with their liexibility to such an extent as to cause marked deterioration of the contact elliciency. By slotting the terminal this deterioration does not occur because the dust or dirt is automatically cleared from the contact surfaces into the slot or slots by successive closures of the switch.

By making the grooves or slots more pronounced or deeper in the case of terminals conducting alternating current, kthe grooves or slots perform a double function of both clearing or cleaning the contact surface, as

above described, and of readily radiatingy from the terminal block such heat as may be generated by the current therein, especially such heat as is due to the skin effect of the alternating current. That is to say, with alternating current, the current is not distributed uniformly through a terminal block but resides principally in its outer layers or surfaces, and the conduction of the current being for this reason through smaller cross sections, the heating effect of the terminal is greater for alternating current than direct current. And the grooves or slots in the terminal blocks serve to more readily radiate or carry off such heat due to the greater radiating surface afforded.

Our invention resides in thefeatures hereinafter described and claimed.

For an illustration for one of the forms our invention may take reference is to be had to the` accompanying drawing, in which: f

Figure 1 isa side elevational view of anr electric switch embodying our invention. Fig. 2 is a front elevational view of terminals such as employed kin Fig. l.

` The laminated bridging or contact member is supported upon arm A which may be pivoted at B and actuated by any suitable mechanism such as a toggle, not shown, which may be connected tothe arm A at C.

T and T1, are fixed or stationary terminals or terminal blocksv against whose front faces the laminfe of member L engage end-on.

When the switch is being closed, as by rotating the arm A in a counter clockwise direction upon its pivot B by a toggle or the like the laminae first engage the faces of the terminals T, Tl and as the pressure upon arm A is continued the ends of the laminee abut more firmly against the terminals and slide or sweep along such faces in a vertical direction as viewed in Fig. 1.

In the contact faces of the terminals T, T1 are slots or grooves S of any suitable cross section or shape. Suppose the switch to have remained open for some time and dust and dirt to have collected upon the terminals and the ends of the laminae of member L, by the closing movement and the sliding or sweeping mentioned the dust or dirt will lodge in these grooves or slots S, producing a clean low resistance contact between the ends of the laminae and the terminals T. T1. And as hereinbefore stated, when using alternating current, these grooves or slots Srmay be made deeper or more pronounced in which case the heat attendant upon the use of alternating current is more easily carried off.

As shown in Fig. 2 the slots or grooves S are inclined with respect to the vertical,

that is, with respect to the direction of sliding or sweeping by the laminas.

Tn the example illustrated there are tWo series or' grooves or slots inclined in different directions with respect to the vertical.

In the example illustrated the contact suriace on the terminals is made up oi a plurality of contact units or areas D separate and distinct from each other. lo lVliile vfe have illustrated a particular example of our invention, it is to be understood that the number, depth and direction of the grooves or slots may be varied greatly and disposed in any suitable direction. F or example, the grooves or slots-may extend at different angles from those illustrated, and there may be only a single series of grooves or slots, or more than the tivo series illustrated. The size, shape and number of 2o Contact areas or units D may be varied greatly from the example illustrated.

Obviously the slotted terminal may constitute the movable Contact member of the switch, and the laminated member may constitute the stationary member of the switch.

TVliat We claim is: l. In an electric switch having a yielding laminated contact member, or means for preventing loss of flexibility of the lamina;

of said member by the packing of material between the saine comprising a rigid coperating terminal having in its Contact face intersecting slots at an angle with the edges of said laminze.

2. ln an electric switch, a laminated contact brush the ends of Whose laminze yield with respect to each other, of means for preventing the packing of material between the ends of said laminae comprising a coperating rigid Contact having the Contact face slotted at an angle to the edges oi said laininae engaging said contact face.

Tn testimony whereof We have hereunto allixed our signatures in the presence of the two subscribing Witnesses.

VILLLLM M. SCOTT. JAMES H. VYATT. THOMAS lV. GREATHEA Witnesses:

ELiixNon T. MCCALL, NELLIE EVANS.

Copies of this patent may be obtained for ve cents each. by addressing tte Commissioner of Patents, Washington, D. C.

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