Patent GB-502934-A (GB)
Title: Improvements in or relating to temperature controlling and ventilating systems
IPC: F24F11/08
Filed: 1938-06-14
Abstract: 502,934. Automatic control systems; thermostats. VAPOR CAR HEATING CO., Inc. June 14,1938, No. 17700. Convention date, Nov. 11, 1937. [Class 38 (iv)] [Also in Group XIII) Temperature.-Air conditioning means for a space 1, such as a railway oar, comprise a blower A conveying outside and inside air taken through apertures 4, 5 respectively, in proportions determined by a damper or shutters 73, past cooling means B and heating means C into a duct 6 having a series of outlets 7, 8 into the apace 1. The heating means also includes a floor heater G automatically controlled at all times by a thermostat J. Thermostats F, L in the space 1 respectively control the heating and cooling means to maintain a given space temperature. The temperature of the air issuing from the duct 6 is limited to a maximum by a thermostat E, but the action of thermostats E, J is modified in accordance with the space temperature by a thermostat F which causes intermittent operation of a relay F<1> controlling heating coils on the thermostats E, J. Thermostats R, S responsive to outside temperature cause operation of the cooling and heating means respectively and define an intermediate range wherein the blower only is operative for ventilating, but the action of these thermostats may be overridden by switches actuated manually or by a humidostat Z if the humidity is excessive. The damper 73 is operated by a reversible motor 75 and a damper 74 may be manually adjustable or coupled to the motor ; preferably these dampers do not wholly close their respective inlets. Thermostats 0, P control a motor operating the damper to reduce the'outside air supply when conditions overload either heater or cooler. In the cooling range, a thermostat M produces a progressive rise of the controlled temperature with rising outside temperature by modifying the action of thermostat L. The action of thermostats L, 0 may be modified automatically according to internal relative humidity. The speed of the blower is automatically controlled to maximum, medium and slow speeds in ventilating, cooling and heating ranges respectively by variation of field strength of its motor. Automatic control of heater C and refrigerator B is inoperative until the blower motor circuit is closed. Reduced. temperature operation at night is obtained by a manual switch. The automatic control of the heaters C, G may be disabled to permit manual operation of the respective valves D, H, which are normally operated by solenoids such as 15, 16, but when outside temperature is above heating range, or the blower is not running, they will be closed automatically. A thermal switch associated with an indicating lamp opens the solenoid circuits if these be continuously energized. All thermostats except R, S have heating coils energized for varying intermittent periods whereby the effective temperature of thermostats E, J, L, 0, P is modified and whereby periodic switching action of thermostats F and M is produced for the control of thermostats E, J and thermostat L respectively. Progressive temperature rise in the cooling range is effected by the increasing periods of application of such current to the coils of thermostats L, 0 by the thermostat M. The humidostats (not shown) control thermostats L, O by passing con. tinuously a current through the heating coils which varies with the relative humidity in the space 1. Overshooting of the controlled temperature is minimized by temporary current through the coils on thermostats E, J, L, O, P when the solenoids of the heating valves are energized, when the thermostat L stops the cooling means B, and when the circuits of the damper motor are energized. The reduced night temperature is produced by current supplied through the day-and-night switch.