GB728281A - Automatic ventilating and cooling system - Google Patents

Abstract

728,281. Automatic temperature control systems. VAPOR HEATING CORPORATION. Dec. 14, 1953 [Jan. 7, 1953], No. 34788/53. Class 38 (4). In a railway car a blower supplies a fixed quantity of air, a proportion of which, dependent on the setting of a motor-driven damper, has passed through a cooler. The amount of cooling is adjustable by a pre-set damper which determines the amount of re-circulated air. Car temperature is maintained constant by thermostats within the car controlling the motor-driven damper. In Fig. 2 the cooler D is switched on and off by a relay C<SP>1</SP> under the control of a thermostat C. A reversible motor 69 operating the damper is controlled by relays A<SP>1</SP> and B<SP>1</SP> under the control of cycling thermostats A and B. Thermostats A, B, C, which are each responsive to car temperature, are biased by heaters 76, 77 and 78 respectively. The operating temperatures of the three thermostats are simultaneously adjustable by operation of a switch E to select, through contacts 3, 4, 5 or 6, a resistor 79, 80, 81 or 82 in series with a parallel arrangement of the thermostat heaters. A resistor 77<SP>1</SP> in series with heater 77 raises the operating temperature of thermostat B relative to thermostats A and C. Switch E may be set to close contact 1 only, to switch on a blower 12 and provide ventilation without temperature control. When switch E is set to close also contact 2 and one of contacts 2, 3, 4 or 5 for automatic control, the cooler D is brought into operation if the temperature rises to the operating temperature of thermostat C. A resistor 101 then increases thermostat heater energization to ensure that the cooler remains operative for a period. At temperatures above the operating temperature of thermostat C the cooler is operative, thermostats A and B operate cyclically, and the arrangement is such that if the temperature rises the change in the relative times of operation of relays A<SP>1</SP> and B<SP>1</SP> causes adjustment of motor 69 to increase the proportion of cooled air but if the temperature falls the change in the relative times of operation of relays A<SP>1</SP> and B1 causes adjustment of motor 69 in the reverse - sense. Thermostat heater energization is modified when heater 76 is switched off by relay A<SP>1</SP>, or when resistor 102 is introduced by relay A<SP>1</SP>. or B<SP>1</SP>. A resistor O is substituted to prevent modification of heater energization when heater 77 is switched off by relay B<SP>1</SP>.