GB647485A - Improvements in or relating to the automatic starting and stopping of gas engines - Google Patents

Abstract

647,485. Automatic temperature control systems; starting prime movers. U.S. THERMO CONTROL CO. July 14, 1947, No. 18727. Convention date, Nov. 16, 1939. [Class 38 (iv)] The temperature, pressure or humidity of an enclosed space 10 is controlled by apparatus including a gas engine 29 (Fig. 1), and a starter generator 37 operable in response to deviations in the variable to be controlled. As applied to temperature control (Fig. 2), a thermostat 11 is adapted to close the circuit of a battery 43 when the temperature exceeds a predetermined value completing a circuit to a master relay 70 and to a high-tension coil 68 connected with the distribution and ignition system of the gas engine. Also included in the circuit are safety devices 44, 62, 55 and 73 adapted to break the circuit in the event of engine over-heating, lack of pressure or excess of pressure in a compressor 16 and excess of current in a relay 84 controlling the gas engine choke 111. Operation of the master relay 70 completes a second battery circuit to the field coil 95 of the starter generator armature 97 through a relay 93. At the same time current passes through generator field coils 96 and through the armature 97 which is thereby caused to generate current to recharge the battery 43. The relay 93 is adapted to operate only when the battery current passes (the subsequent generator current being insufficient to cause operation), thus completing the battery circuit to the relay 84, causing the choke 111 to be operated only on the initial starting of the generator. The choke is operated through a thermostatic arm 107 so that if the engine is already hot, operation of the relay 84 will not operate the choke 111. A humidostat 166 is also adapted to function upon the operation of the thermostat 11. The gas engine 29 (Fig. 1) drives the compressor 16 furnishing a condenser 21 with compressed gas through a reversible valve 19. The gas is then passed to a compressed refrigerant tank 23 and thence to the header 25 of an evaporator heat exchanger 12 from whence it returns via valve 19 to the compressor 16. Air is circulated through the evaporator 12 and space 10 via ducts 13 and 14 by a blower 15. When the apparatus is used for cooling the space 10, defrosting of the cooling coils (not shown) connected to the header 25 is effected by an aneroid 114 responsive to decreases in air pressure in a space 113. Expansion of the aneroid completes a circuit to a relay 121 (Fig. 2), the condition of which determines the direction of rotation of a reversible motor 129 operating the valve 19. The motor is restricted to a 90 degree movement by a lever 158 connected on its shaft and co-operating with circuit breaks 151 and 156. Energization of the relay 121 by the aneroid causes the motor to position the valve 19 for defrosting, whilst in the de-energized state of relay 121 the motor positions valve 19 for cooling.