Patent GB-889737-A (GB)
Title: Improvements relating to thermostatic control apparatus for electrical vehicle-heating systems
Inventor: VIDAL JOHN FURSE BANCROFT
IPC: G05D23/22
Filed: 1959-03-13
Abstract: 889,737. Automatic temperature-control systems. STONE & CO. (DEPTFORD) Ltd., J. May 31, 1960 [March 13, 1959], No. 8852/59. Class 38 (4). Thermostatic apparatus for the control of electrical vehicle-heating systems is adapted for controlling the temperature inside a railway coach in dependence upon conditions affected by the temperature outside the coach. As shown, a heat-loss simulator for a railway coach comprises two steel boxes 14, 15 having a dead air-space 16 between them and two cooling tubes 28 extending there through. Within the inner box, one section 19 of a heater is mounted beneath the bulb 22 of a thermostat 12 and the other section 18 is wound around a steel tube 21 containing a heat-absorbing slug 23 which may be of copper or iron and which is adjustable within the tube. The coach heaters 1 are fed from the traction supply and are controlled by the thermostat 12, a relay 7 and a contactor 4; the heater 18, 19 is energized by current taken by one of the coach heaters. Tappings 26 permit the power supplied to the simulator to be adjusted and also the proportion of power supplied to the two sections 18, 19 of the heater. The simulator is disposed wholly or partly outside the coach and may be below the floor with the tubes 28 extending fore and aft of the coach. Upon switching on the heaters 1 after the coach has been standing without heat for a number of hours, a considerable proportion of the heat developed in the heater section 18 is taken up by the body 23, and the thermostat bulb 22 will be insufficiently heated to initiate regulation action; the coach will thus be rapidly preheated. When the body 23 no longer takes up a substantial proportion of the heat developed by the heater section 18, the resulting increase in heat in the region of the bulb 22 will initiate a cycling action of the thermostat and an even temperature of the coach be maintained. The additional heat loss occurring when the coach is in motion and its windows are open is simulated by the air flow through the tubes 28. Caps placed on their ends or variable orifices inserted in the tubes may adjust the flow. The cycling frequency of the thermostat may be adjusted by a movable thermally-insulating sleeve 22a. In a modified circuit, Fig. 4 (not shown), the relay and contactor windings are energized by rectified current from the heating bus line instead of from the lighting battery. A further construction of simulator, Fig. 5, comprises a heater 33 which may be connected across a potentiometer in the main heating circuit or in series with a variable resistance. The heater surrounds a heat-absorbing cylinder 23a and a further heat-absorbing body 23b, 36 is adjustably mounted in the cylinder. The bulb of the thermostat is embedded in aluminium powder contained in a metal thimble 34. A number of thermostats set a few degrees apart may be controlled by a switch accessible to the guard. Control apparatus in one coach may be arranged to control the heating of another similar vehicle. According to the Provisional Specification, the invention is not restricted to heating systems for vehicles.