Patent GB-679181-A (GB)
Title: Improvements in and relating to reversible thermostatic valve systems
IPC: F24F11/08
Filed: 1949-01-10
Abstract: 679,181. Thermally-actuated valves ; automatic temperature control systems. BRITISH THOMSONHOUSTON CO., Ltd. Jan. 10, 1949 [Jan. 16, 1948], No. 656/49. Class 135 [Also in Group XXXV] In a reversible thermostatic valve system for controlling the flow of heat exchange fluid through a circulating pipe over which flows air &c., the inlet pipe for the fluid has a valve for modulating the flow of heating or cooling fluid and associated with the valve a thermal bellows mechanism and shiftable fulcrum means for effecting opposite movements of the valve. As shown applied to the air conditioning unit for a room, the passage of heating or cooling medium from the pipe 17, Fig. 1, through a heatexchanger 12 in a duct 13 through which the air passes to the room to an outlet 59 is controlled by a spring-loaded valve 20 operated through a lever 31 by a thermal phial 40 and bellows 28. An increase in air temperature may open the valve 20 during cooling or, as shown, close it during heating according to whether the lever 31 pivots about the point 34 or 36 respectively. When heating medium is used, the thermal phial 55 at the inlet to the exchanger will produce a greater vapour pressure on top of a diaphragm 51 than the pressure beneath produced by the phial 58 at the outlet to the exchanger, so that the diaphragm moves downwards and, by means of a frame 42, makes the pivot 34 operative. When cooling medium is used, the diaphragm 51 rises to render the pivot 36 operative. The phials 55, 58 may be responsive to the air temperature on either side of the exchanger. In a modification, heating or cooling medium is bye-passed around the valve through three auxiliary heat exchangers 84, 85, 86, Fig. 3, the exchanger 84 being at a higher or lower temperature than the exchanger 86 according to whether exchanger 85 is gaining heat with cooling medium, or losing heat with heating medium. The consequential difference in vapour pressures in the chambers 74, 76, moves the diaphragms 75, 77 to move a pin 70 from one end to the other of a slot 71 in a lever 66 so that the valve opens or closes on a rise in the air temperature. In a further modification, the walls of the chambers 74, 76 are exposed directly to the inlet air and the heat exchange medium respectively. In this case, the heat exchangers are dispensed with. The Specification, as open to inspection under Section 91 includes apparatus for attemperating the air in a room comprising a heat exchanger 90, Fig. 5 (Cancelled) over which the air is circulated by a fan 101 and a valve 92 for controlling the flow of heating or cooling fluid to the heat exchanger, the valve being regulated through reduction gear 95 by an electrical motor 94 the direction of rotation of which is controlled by either of two thermostats 96, 97 according to whether the air is to be heated or cooled. The thermostats are disposed in circuits the supply of current to which is controlled by a pivoted switch arm 104 arranged in series with the secondary coil of a transformer 109 and actuated by a rod 79 connected to the flexible walls 75, 77 of chambers 74, 76 charged with volatile liquid. Heating or cooling fluid bye-passed around the valve flows through coils in the chambers and also through an auxiliary heatexchange coil 85 preferably located between the fan and the heat exchanger 90. When heating fluid is supplied through the pipe 91 to the heat exchanger 90, the bye-passed portion flowing through the coils in the chambers 74, 76 maintains a higher temperature and pressure in the chamber 76 than in the chamber 74 with the result that the rod 79 moves the switch arm 104 on to the contact 105. so that the motor is controlled by the thermostat 96. When the room temperature rises above the desired value, the thermostat makes the contact 108 and the motor rotates in a direction to close the valve 92. A fall in room temperature results in the thermostat making the contact 116 so that the motor rotates in the reverse direction to open the valve. If the room is to be cooled, cooling fluid is supplied to the heat exchanger 90 and the bye-passed portion maintains a lower temperature and pressure in the chamber 76 than in the chamber 74 so that the switch arm 104 makes the contact 106 and the motor is controlled by the thermostat 97. This subject-matter does not appear in the Specification as accepted.