Patent GB-659985-A (GB)
Title: Improvements in temperature control systems
IPC: F24F11/76
Filed: 1949-11-22
Abstract: 659,985. Automatic temperature control systems. VAPOR HEATING CORPORATION. Nov. 22, 1949, No. 29926. [Class 38 (iv)] A system for controlling the temperature in a railway car comprises a cooler A1 controlled by an electro-magnet F<SP>1</SP>, a primary heater A (Fig. 1) operated by a valve 11 and electromagnet F, and secondary heaters B, B1, B2, &c., in the floor of each compartment, operated by valves 14 and electromagnets M, M1, M2, &c. Assuming the outside temperature to be below 50‹ F. a main relay N under the control of the main thermostat P is in the position shown in Fig. 3, contacts 1, 2 and 4 being closed. Connected in circuit with the closed contacts 1, 2 are relays R, R1 controlled by thermostats 36, 36a in the compartments. As long as the relays R, R1 are de-energized electro-magnets M, M1 are also de-energized and heat is applied through the valve 14 to the secondary heaters. If, however, the temperature in the compartments rises above a value set by resistors 75, 75a, the relays are short-circuited by the thermostats 36, 36a energizing the electromagnets M, M<SP>1</SP> to close the valve 14. The electromagnet F of the main heater A is operated by contacts 52 of a relay V controlled by a thermostat T inside the car- If the temperature inside the car is below a predetermined value the coil U of the relay V is energized over a circuit including a resistor 43, coil U, and resistor 49. If, however, the temperature rises the coil is shortcircuited by a circuit including the closed contacts 4 of the main relay N and the closed contacts of the thermostat T. The thermostat T is provided with an auxiliary heater 63, part of the heating current to which is applied over contacts 52 of the relay V when energized to effect a cycling operation. A second part of the heating current to the auxiliary heater is supplied over a path including an outside thermostat X and such that if the outside temperature falls below 0‹ F. this heating current is substantially reduced, thereby increasing the functional setting of the thermostat T. If the outside temperature rises above 50‹ F. the solenoid O of the main relay N becomes energized thereby breaking contacts 1, 2 and 4 and closing contacts 3 and 5. The secondary heaters are thereby rendered inoperative, a circuit is made ready for a cooling thermostat Y inside the car and control of the main heater is passed from thermostat T to a thermostat .W operating in the same manner as thermostat T, additional heating current for the auxiliary heater 80 being provided over contacts 85 of the relay V when energized. If the temperature inside the car exceeds a second predetermined value such that the thermostat W maintains the relay V deenergized, the cooling thermostat Y causes operation of a relay Z1 to energize a compressor 102 and electromagnet F1 to operate the cooler A1. At the same time more heating current is applied to auxiliary heater 80 of the thermostat W by a circuit over the contacts 103 of relay Z1. This heating current is sufficient to maintain the thermostat W out of control until the temperature falls below the second predetermined temperature for a substantial length of time.