Patent GB-628256-A (GB)
Title: Automatic temperature control
IPC: B61D27/00
Filed: 1946-03-06
Abstract: 628,256. Automatic control systems. MERCER, R. (Vapor Car Heating Co., Inc.). March 6, 1946, No. 7032. [Class 38 (iv)] In a railway car air-temperature control system, in which thermostats regulate both the heating and cooling devices, the thermostats are provided with auxiliary heating coils adjustable by means of shunt circuits. As shown, the railway car floor radiators, e.g. B, Fig. 1, and C and D (not shown), are each controlled by one of the thermostats G, G<SP>1</SP>, G<SP>11</SP>, which close steam valves, e.g. E, when the temperature exceeds 76‹ F. Roof radiator H is similarly controlled by thermostat L, closing steam valve 16 when the temperature exceeds 76‹ F. A motor-driven fan M carries heat from the radiator H into the car, the motor being controlled by a thermostat N so as to be cut-out when the temperature at N drops below 60‹ F. Two coolers 1, 2 are each controlled by valves S, V, operated by thermostats U, X, opening the valves S, V at 76‹ F. and 77‹ F. respectively. Thermostats G, G<SP>1</SP>, G<SP>11</SP> and L, U, X are each associated with an auxiliary heating winding, e.g. 18, 19, 20. A manually-operated switch enables floor heaters to be operated alone or in combination with the roof heaters and coolers. Operation of floor radiators alone. The manually-operated switch is operated to open contacts Z1, Z2, Fig. 7, and close contacts Z<SP>3</SP>. When the car temperature rises above the desired normal, thermostats G, G<SP>1</SP>, G<SP>11</SP>, operate to actuate relays F, F<SP>1</SP>, F<SP>11</SP> which close the steam valves and supply an additional current to auxiliary heaters 18, 19, 20 over resistance 50 to prevent the thermostats releasing relays F, F<SP>1</SP>, Fll until the car temperature has dropped a predetermined extent. Combined operation of floor and roof radiators. With an assumed initial car temperature below 60‹ F. and with the master switch set to close Zl, Z<SP>2</SP> and open contacts Z<SP>3</SP>, the heaters 18, 19, 20 of thermostats G, G<SP>1</SP>, and G<SP>11</SP>, receive heating current and steam is supplied to radiators B, C, D. Solenoid 57 is energized, thereby operating relay K which closes the contacts 62 to complete the circuit of solenoid J which opens the valve 16 supplying steam to the overhead heater H. Heating of the space A is thus effected simultaneously by radiators B, C, D and the heater H, but the fan M remains inactive until the temperature rises to 60‹ F. when the solenoid 69 is short-circuited by the thermostat N, and relay AA is operated to close the contacts 73. This energizes the solenoid 75 of relay BB and the fan circuit is completed through contacts 77. " Inching " of floor radiator thermostat. Upon the space temperature reaching 76‹ F. the thermostat L short-circuits the solenoid 57, the contacts 62 and 84 open and close respectively, to close the steam supply valve 16 to the overhead heater H, and to insert an auxiliary heating circuit in series with the heaters 18, 19, 20 through the resistor 87. The opening of the thermostats G, G<SP>1</SP>, G<SP>11</SP> is thus delayed and the frequency of the " inching " action is reduced. Overhead thermostat control. Changes in the relative humidity of the air in space A are allowed for by manually setting the switch 92 which controls the current to the series connected heating coils 89, 90, 91 of the thermostats L, U, X. The three settings 103, 94, 108 of switch 92 are associated respectively with resistors'105, 96, 110, which change the currents through the heaters 89, 90, 91 and hence control the operating temperature of the thermostats L, U, X accordingly. " Inching " of the overhead heater thermostat. Upon closure of contact 62, i.e. during the operation of the overhead heater H, additional heating current is supplied to the auxiliary heater 89 of thermostat L, through wires 66, resistor 112, and wire 100, and inching of the thermostat and heater H occurs at lower than the datum temperature of the thermostat. Transfer to cooling function. Upon the outside temperature rising to 40‹ F. and if the car temperature is sufficient to cause thermostat U contacts to bridge, then the contacts of thermostat Y close, the solenoid 125 of relay T is energized and contacts 127 close. Additional heating current is thus supplied, through the resistor 137 to heaters 18, 19, 20 of the floor thermostats G, G<SP>1</SP>, G<SP>11</SP>. Radiators B, C, D are held inoperative and the cooling apparatus functions until the space temperature falls when (1) thermostat U opens, to cause contacts 127 of relay T to open to reduce the current supplied to the heaters of the floor thermostats G, G<SP>1</SP>, G<SP>11</SP> which thereupon restart the floor heaters B, C, D and (2) thermostat L opens and the overhead heater H is restarted. No. 1 cooler control circuit. When thermostat U closes, in addition to effecting an additional flow of current to the thermostat heaters' 18, 19, 20, the contacts 139 of the relay T close and the compressor motor O, Fig. 6, is started simultaneously with the opening of refrigerant valve S in cooler 1. No. 2 cooler control circuit. In the event of the temperature of space A continuing to rise, the contacts of thermostat X will close, the coil 147 of relay W is energized, the contacts 154 close, and the valve V of cooler 2 is opened. Simultaneously, additional heating current is supplied to the heating coil 90 of thermostat U and the current to heater 91 is reduced, to cause intermittent operation of thermostat X and thus also of cooler 2. Differential adjustment of thermostat. At external temperatures over 30‹ F. the contacts 157 of the external thermostat CC are closed and an additional heating current is supplied to the heaters 89, 90, 91 of thermostats L, U, X which therefore operate at a slightly lower car temperature than when the external temperature is below 30‹ F. When, however, the external temperature reaches .85‹ F, contact 161 of thermostat CC is made, additional current is supplied to heater 89 while current is shunted from the heaters 90, 91 and thus the car temperature is caused to rise slightly and the difference between it and the outer temperature falls. In a modification (not shown) the thermo-stats L, U, X are replaced by others of the wet and dry bulb type which automatically control the heater H and coolers 1, 2 in accordance with condition of space A and the switch 92 is eliminated.