Patent GB-318308-A (GB)
Title: Improvements in or relating to means for the control of temperature
IPC: G05D23/20
Filed: 1928-06-05
Abstract: 318,308. Electroflo Meters Co., Ltd., (Republic Flow Meters Co.). June 5, 1928. Thermostats. - A device for controlling temperature comprises a temperature-responsive index 11, Fig. 7, a guide member 40 the position of which is dependent on the position of the index, a mechanically-reciprocated member 39 which moves up and down on one or other side of the member 40 according to the position of the latter, and a switch or valve controlling member 50 the position of which is determined by the path of the member 39. The member 39 hangs from a crank 36 on a continuously or intermittently rotated shaft 34 which also carries a cam 33 adapted to reciprocate a bell-crank lever 30, 27, which in turn reciprocates a lever 17. At certain temperatures the downward movement of the lever 17 is intercepted by the index 11 and when this is the case, the member 40 is held by its spring 60 in the position shown in Fig. 7 with its lower end against a stop 62. The member 39 moves up and down on the right hand side of the member 40 and the member 50 remains in the position shown. Should, however, the temperature pass a certain point, the index 11 no longer restrains the lever 17 and accordingly when the member 39 is in its lowest position, a, roller 31 on the lever 30 moves into the hollow portion of the cam and the lower end 32 of the lever presses the member 40 about its pivot 41 till its upper end engages the stop 61. The member 39 now moves up the left hand side of the member 40 and lifts the switch member 50 into its " on " position in which it is held latched by a catch 44 and remains so latched till the temperature changes so that the index 11 again engages the lever 17. When this happens the first upward movement of the member 39 on the right hand side of the member 40 will move the catch 44 out of engagement with the member 50 which will then fall again into the position shown in Fig. 7. A recording device for making a permanent record of the temperature may be associated with the index 11 (Fig. 9, not shown). The member 50 which controls the supply of heat may carry a mercury switch as shown in Fig. 7 or the rotation of its shaft 51 may operate a switch or valve in other ways. The temperature-responsive index 11 may be a needle connected to the armature of a galvanometer connected to a thermo-couple associated with the furnace &c. to be regulated. Fig. 10 shows a simple system of temperature regulation, the thermo-couple 102 causing the actuation of the needle 11 which in turn by means of the device described above controls the position of the mercury switch 104 which connects or disconnects a heating unit 107 to or from the source of supply 106. In a modification (Fig. 11, not shown), the mercury switch closes a circuit to an electromagnet which operates valves controlling the supply of fluid to a burner or injector. In another modification, (Fig. 12, not shown) the mercury switch closes a circuit to a relay controlling the heating circuit. Fig. 13 shows a system in which the mercury switch has a pair of contacts at each end of the tube. Connection of the one pair of contacts by the mercury closes a circuit to an electromagnet 413 which thereupon attracts two armatures 414, 421, the former closing a maintaining circuit and the latter closing the circuit to the heater 418. When the mercury tube is tilted into its other position, the winding 413 is short-circuited, the armatures fall away and the heater circuit is opened. Fig. 14 shows an arrangement in which the mercury switch is dispensed with, the shaft 51 of the member 50, Fig. 7, being prolonged at 505 and operating switch arms 513 through dead-centre quick-action mechanism. In a modification, (Fig. 15, not shown) the shaft operates fluid-controlling valves.