US1047524A - Contact-terminal for interrupting electric circuits. - Google Patents

Description

APPLICATION FILED FEB. 1, 1911.

Patented Dec. 17,1912.

, INVENTOR @aff/o- /ono/a QM M ATTORNEYS in ".the ordinary UNITED STATES PATENT OFFICE.

GOTTLDB HONOLD, 0F STUTTGART, GERMANY, ASSIGNOR TO THE FIRM OF ROBERT BOSCH, OF STUTTGART, GERMANY.

CONTACT-TERMINAL FOR INTERRUPTING ELECTRIC CIRCUITS.

Specification of Letters Patent.

Patented Dec. 17, 1912.

Apptication filed February 1, 1911. Serial No. 606,035.

scription of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

This invention relates to contact terminals for interrupting electric circuits, and more particularly to one employed in devices for ignition of the gas mixture in combustion engines.

Upon interrupting an electric circuit there is produced attho place of interruption a spark having the nature of an arc, in consequence of which, in cases wherein the electrical energy stored in the circuit is to be utilized at a point other than the place of interruption, a large proportion of the energy is lost. This is especially true devices for the ignition of the gas mixture in combustion engines wherein the interruption of a circuit for the production of a high inductive effect at the place of ignition is employed. In fact, this difliculty is of such marked degree that the formation of the spark at the place of ignition in the engine cylinder is greatly interfered with or the spark greatly reduced in intensity.

As tests have shown, the formation of the I are at the place of interruption, is due to the fact that the arc travels along the interrupter contacts and burns the neighboring metal parts, whereby metallic vapors are produced and deposited upon the contact surfaces of the interrupter, so that these surfaces become coated with the oxidized metal until the formation and propagation of an arc is facilitated to an extraordinary degree.

The invention consists in forming the interrupter contacts from some metal that strongly resists oxidation, such as platinum or the like, and giving them such shape that the path along the platinum surface from the place of interruption to the sup porting metal of more easily oxidizable nature is as long as possible, and is preferably interrupted by one or more sharp edges. In this manner the spark or arcforming at the place of interruption is prevented from reaching the more easily oxidizable metal. In the devices of this kind heretofore used, the aredue to an interruption formed between the edge of the contact member and the closely adjacent support of brass or other easily oxidizable metal, in consequence of which the brass or other metal was heated until it generated a vapor which coated the contact surfaces.

In the accompanying drawings forming a part of'this specification, Figures 1 to (3,

show various modifications of contact terminals constructed in accordance with my,

invention.

In Figs. 1, 2 and 3, the contact member or head portion 6 of platinum or other metal strongly resisting oxidation is wider than the body portion a of brass or other metal of more easily oxidizable nature, in order to produce the desired result. In this Way, the body portion is set back from the edge of the head portion, so that an arc must considerably lengthen in order to travel from the edge of the top portion to the body portion, which action is prevented by the fact that the distance between the head portions of the cooperating electrodes at the place of interruption is materially less than the arcing distance from either head portion to the support of the cooperating electrode.

The entire contact terminal may be made of platinum as in Fig. 1. Or it may consist of a head portion 6 of platinum extending outwardly of the body portion a of brass or the like and fastened thereto by solder or any other suitable means, as in Fig. 2. In the construction shown in Fig. 3, the platinum plate (2 covers the top and side of the head ofthe body portion a of braw. According to Fig. 4, the construction is changed in such a way that the brass body portion a is inclosed by a platinum sleeve in which grooves are turned for the purpose of further lengthening the platinum path and preventing the passage of the are to the support. In Figs. 5 and 6, the desired result is secured by providing the platinum collar 6 for the raised portion of the contact surface a. In this case the entire raised portion comprising the contact member a and the collar 2) can be made of a solid piece of platinum as in Fig. 5; or, a properly shaped body portion a of cheap metal like brass can be covered with a thin layer .of platinum, shaped so as to form a contact member and a protecting plate, as shown in Fig. 6. The same idea may be used whether the support f recedes from the contact member 6 as indicated in Fig. 1, or whether it slides along the surface of the contact member as indicated in Fig. 2, to

interrupt the electric circuit. In all cases the body portion a of each of the cooperating electrodes extends materiall away from the support so that neither the ody portion a nor the supports f of either electrode is ever traversed by the arc.

Having thus described my invention, what I claim is:

A circuit interrupting device for ignition systems for internal combustion engines comprising relatively movable cooperating electrodes of substantially the same shape and supports therefor of more easily oxidizable metal, each electrode having a body portion extendin materially away from its support, and a at head portion of metal strongly resisting oxidation extending outwardly from the body' ortion and clear of the support and shape so that it includes a sharp edge. in "the path of an are from the place of interruption of the circuit to the support along-the surface of the electrode and so that the distance between the head portions of the cooperating electrodes at the place of interruption is materially less than the arcing distance from either head portion to the support of the cooperating electrode. 1

In testimony whereof I affix my signature, in presence of two witnesses.

GOTTLOB HONOLD.

Witnesses MAX ANscHI'i'rz, -REINHOLD ELWERT.

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