Patent GB-498093-A (GB)
Abstract: 498,093. Interrupters. TERRELL, J. R. F. Nov. 19, 1937, No. 31813. Convention date, Nov. 19, 1936. [Class 38 (v)] [Also in Group XXXV] An electric switch is operated by a cam along which it may be moved so that the ratio of open to closed periods depends upon its position and means are provided to stop the rotation of the cam when the switch position is such that it is continuously open or continuously closed. The switch may be shunted by a resistance. A mercury switch 24 is mounted on a carriage 21 which may be traversed along guides 22 by a projection 31 engaging a groove 32 in a rotatable plate 33 to determine its position in relation to a cylindrical cam 20 which is continuously rotated by a motor 14. The switch 24 is secured in a cradle 26 pivoted at 25 on the carriage and a spring 29 holds an abutment 27 in contact with the cam. The carriage 21 is adapted to abut elements 40, 41 attached to the contacts of normally closed switches 43, in series with the circuit of the motor 14, when the abutment 27 reaches either end of the cam. The cam may be a portion of a metal tube. Several cams, each operating upon a separate independently adjustable switch, may be driven by the same motor, all the switch pairs 43 being connected in parallel in the motor circuit. The speed of the motor may be varied by a rheostat to change the periodicity of switching. Fig. 6 shows an arrangement for thermostatic control of the carriage by a lever 65 which is operated from a thermostat bulb adjacent to a heating or cooking element in the circuit controlled by the switch. Fluid in a capillary tube 47 actuates a plunger-rod 51 having a head 54 by which its movement is transmitted to a hydraulic multiplier 60 actuating the lever 65 through a pantograph coupling 64. The period of energization of the heating circuit controlled by the cam-operated switch is thus reduced in accordance with increasing temperature. Adjustment of the temperature control is effected by a knob 56 whereby the head 54 may be turned upon the screwed rod 51. The Specification as open to inspection under Sect. 91 described also circuit interrupting means, Fig. 7 (Cancelled), comprising solenoids 75, 76 in series respectively with contact pairs 71, 73 alternately closed by a thermally actuated member 70 and thereby continuously oscillating a coupling member 88, on manual closure of a switch 94, at a periodicity determined by a rheostat 90 in series with the heating element 69 on the member 70. A switch 82 in series with a load circuit 93<1> is thus intermittently closed. Intermittent heating of the thermal member is produced by a switch 81. Fig. 8 (Cancelled) also showed a contact strip 99 reciprocated over a fixed path by a continuously driven crank 97 and intermittently engaging contacts 100 for periods determined by the adjustment of a nut 106 on a threaded rod 107 determining the position of a plate 102. The member 101 carrying the contacts 100 is controlled by springs 104 and stop pins 103. The plate 102 is adapted to open the circuit of the motor driving the crank 97 when in its end positions by engaging contacts 112. This subject-matter does not appear in the Specification as accepted.