Patent GB-615567-A (GB)
Title: Improvements in, or relating to, air conditioning apparatus
IPC: F24F6/04
Filed: 1946-05-18
Abstract: 615,567. Automatic control systems for air-conditioning apparatus. BIRLEC, Ltd., and HARRIS, J. May 18, 1946, No. 15126. [Class 38 (iv)] [Also in Groups X and XII] In an air-conditioning apparatus (see Groups X and XII) which comprises a number of air-wetting and/or air - drying units arranged on a hollow base divided internally into an inlet and an outlet chamber, air flows into and through the air-conditioning units through valved ports, one at least of each pair of valves being under the control of a humidistat and actuated either by a solenoid or by a reversible electric motor. As shown in Fig. 9, the humidistat 21 is adapted when the arm 28 is in either of its extreme positions to energize through the lines 26 or 27 all or any of the four solenoids 24 which open against controlling springs the inlet valves to four airconditioning units' which may be any combination of wetting or drying units, each unit operating the switch 25 to connect the solenoid to the appropriate circuits of a wetting or drying unit, the inlet valves returning to their closed position when the condition of the air is adjusted. In the modification shown in Fig. 12, each pair of valves is operated by a reversible motor 80 associated with a pair of two-way unit-operated switches 25d and 25w adapted to open and close the circuits in which the two windings of the motor are connected, one switch opening one winding circuit and closing the other when actuated by an airconditioning unit, and the second switch closing the one winding circuit and opening the other when actuated by an air-conditioning unit, each drying unit being adapted to operate a switch 25d and each wetting unit a switch 25w. Each switch 25d, 25w comprises a change-over switch 25d1, 25w1 and a make-and-break switch 25d2, 25w2, and each motor includes a limit switch in each winding. The circuits of the humidistat 21 are completed through relays 96 and 107, contact of the arm 21c with the terminal 21a or 21b opening the valves to the drying or wetting units until the condition is adjusted and the arm 21c swings out of contact. In operation, for example, a drying unit placed in position upon the base operates the switch 25d to change-over the switch 25d1 from the position shown and to close the switch 25d2. The change-over connects the closing winding of the motor through lines 88, 89, 93, switch 25d2, line 94, contact 95 of the relay 96, lines 97 and 92 to the sources of current supply so that the valves are held in their closed position. When, however, the humidity of the air is greater than desired, the arm 21c of the humidistat contacts the terminal 21a, energizes the coil 100 of the relay 96, thus breaking the circuit through the closing winding and completing a circuit through line 88, limit switch . 86, the opening winding of the motor, lines 102, 103, switch 25d1, line 104, relay contact 95, lines 97 and 92 so that the motor is driven to open the valves of the drying unit until the desired degree of humidity is reached, when the arm 21c swings away from the terminal 21a and breaks the circuit of the relay coil allowing the relay contact 95 to return to its initial position when the circuit through the closing winding is again completed and the valves return to their closed position. When the valves are driven to either of the extreme positions, the corresponding limit switch is opened, bringing the motor to rest. The valves may of course assume a floating position intermediate between the fully opened and closed positions. The wetting units are brought into operation when the air is too dry, in like manner through the relay 107 and the control system provides that when a unit is removed from the base the circuit including the closing winding of the motor is completed, maintaining or bringing the valves to their closed positions. To control the temperature of the conditioned air, each supply conduit has a three-way valve controlled by a thermostat enabling some or all of the air as may be necessary to be diverted to pass through heating or cooling means.