GB1194580A - Heating and Cooling of Passenger Compartments - Google Patents

Abstract

1,194,580. Automatic temperature control systems. ALEX FRIEDMANN K.G. Nov. 14, 1967 [Dec. 2, 1966], No.51730/67. Heading G3R. In a method of air conditioning passenger compartments particularly of railway trains, a measured temperature is compared with determined upper, intermediate, and lower temperature references such that at the upper temperature a cooling unit is prepared for operation and a heating unit disabled, at the lower temperature a heating unit is prepared and a cooling unit disabled, the output of either unit at any one time being controlled as a function of the measured temperature in relation to the intermediate reference. The heating and cooling units may be subdivided and one or more parts introduced in turn with a time delay. A temperature detector 7 controls a relay 10 operating contacts 10 1 and hence a relay 12 controlling a heating unit (not shown). As the temperature rises another detector operates another relay 11 closing contacts 11 1 which through already closed contacts 10 2 energizes a relay 15 which is held over its own contacts 15 2 contacts 15 1 disabling the relay 12, and contacts 15 3 energizing through contacts 10 3 a relay 16 which prepares a portion of a cooling unit. Simultaneously a timing relay 18 2 is energized which after a determined delay opens its own contacts 18 1 and closes contacts 18 2 energizing a relay 17 preparing a second portion of the cooling unit. The cooling unit is then controlled by detector 7 until a low temperature is sensed by a detector 6 when relay 9 is de-energized, opening contacts 9 1 which through relay 15 disconnects the cooling unit and prepares the heating circuit through contacts 15 1 . A high temperature safety cut out 13 may be provided, and a thermostatic switch 14 responsive to low outside temperature may disable the cooling circuit.