Patent GB-190712967-A (GB)
Title: An Improved Switch for Controlling Electrical Circuits.
Inventor: RORKE THOMAS JOSEPH
Filed: 1907-06-04
Granted: 1908-07-06
Abstract: 12,967. Rorke, T. J., and Rorke, E. June 4. Switches.-Relates to electric switches of the type adapted to be rocked into the closed and open positions by electro-magnetic action, in which a tubular arm, rocked by such action, is overbalanced by an independent weight which automatically breaks the circuit of the actuating electro-magnet, and consists in the provision of one or more auxiliary spark-taking carbon contacts in addition to the main circuit-closing contacts. The carbon contacts are yieldingly mounted, and are in electric connexion with the main contacts, which are of the ordinary mercury-pot type. As shown in Fig. 1, the lower carbon H' is mounted buoyantly in mercury, its upward tiavel being limited by a washer or collar h. An insulated contact H<3>, Fig. 4, may be arranged in the mercury pot H<2>, so that, after a predetermined amount of wear of the carbons H, H<1>, the mercury will not be displaced sufficiently to reach the contact H<3>. If this contact is in the circuit of the opening electro-magnet F, the switch cannot then be operated to the 'off' position. The carbon contacts may be in duple, triple, or other form, their mercury containers being made.in one piece or casting if desired. A modification is described, Fig. 8, in which a transversely-mounted carbon H coacts with a pivoted carbon H<2>, extended movement causing the carrier H<9> subsequently to dip into the mercury. The independent weight, namely, mercury, in the rocking tube J serves in conjunction with contacts J<2> to make and break the circuits of the actuating electro-magnets F, F<1> in the known manner, and also to hold the switch.in its closed of open positions. Balls or spheres in suitable guides may be used instead of the tube J and mercury. To avoid 'hunting,' an auxiliary contact is arranged on the rocking frame C on the side remote from the contacts H, H<1>, so that, when the frame vibrates slightly towards the 'off' position, the circuit of the electro-magnet F is closed at the auxiliary contact to operate the switch. Modifications are described in which solenoid plungers are used for rocking the frame C, a permanent magnet being mounted between the carbon contacts H, H<1> for rupturing any arc that may be formed. If sets of contacts are mounted at each end of the frame, the switch is applicable as a double-pole changeover switch. A layer of oil may cover the surface of the mercury in the different pots. According to the Provisional Specification, the circuits of the actuating electro-magnets maybe made and broken by means of contacts on the rocking frame and mercury pots upon the base. The sparking carbons may be spring-mounted, various methods of doing this being described. The overbalancing may be obtained by providing the rocking frame with an upstanding arm having a weight, spring, or solenoid control ; or, the arm and frame may be rocked or balanced by electro-magnetic action. The sides of the frame may be extended downwards and the counterbalancing effect obtained by weights or springs. The switch may be used for controlling electric stoves &c. by means of a thermostat or maximum-and-minimum thermometer, either directly or with the addition of a relay. Electric signs, lights, &c. may be controlled by means of a multiple-contact clock.