Patent GB-821476-A (GB)
Title: Apparatus for integrating over a period of time the heat absorbing capacity of an environment
IPC: G01K17/04
Filed: 1957-03-25
Abstract: 821,476. Measuring heat quantities. LAMB, M. R., [formerly JOHNSON, M. R.]. March 25, 1957, No. 9704/57. Class 97(3) Apparatus for integrating, over a period of time, the heat absorbing capacity of an environment comprises a chamber in heat exchange relationship with the environment, a thermostatically controlled electrical neater to maintain the temperature of the chamber constant and means for recording the total time during which the heater is switched on. In the form shown an insulated housing 11 is mounted on a tubular support 19 in an open location and contains a thermostat 25 and heating elements 23. Another housing, somewhat similar, but having louvred sides, contains at least one reverse thermostat, i.e. one closed above the operating point indicated at 55 in Fig. 4. Parts shown in the circuit diagram but not contained in either of the housing referred to are separately housed. The interior of the housing 11 is maintained at a constant temperature by the thermostat 25 which, when required, connects the primary of a constant voltage device 28 to an A.C. source, the secondary feeding the heating element 23 through an adjustable resistance 29. A synchronous motor 71 is connected to run when the heating current is switched on and the total distance run is a measure of the heat supplied to, and so of the heat lost from the housing 11. The motor rotates, through reduction gearing, a disc 73 having a cam 74 which, for each revolution, closes a switch to produce a pulse which is fed to a counter 72, the indication of which is thus a measure of the heat loss. In an alternative arrangement this indication is provided by a synchronous clock mechanism connected in place of the motor 71 and replacing the motor and the associating counting mechanism. Closure of the switch 75 also energizes a solenoid 79 to close a switch 81 which keeps the motor circuit energized, if the thermostat 25 should open when the switch 75 is closed, until the switch 75 opens again. Energization of the solenoid also moves a change over switch 82 to a position to connect a counter 95 to the power supply so that this records pulses at the same time as the counter 72. When the solenoid 79 is deenergized, however, the counter 95 also receives pulses produced by the closure of the switch 97 by cams 96 on a disc 105 driven by a continuous running motor 89. Closure of the switch 97 also energizes the heating coil 98 of a normally closed thermally operated switch 101 which then opens to break the counter circuit. As explained in the Specification, the indications of the counter 72 provide a measure of the fuel-oil requirements of . a house, the oil being used for space heating only. The indications of the counter 95 provide an indication of the requirements of a house where the oil is used for water heating. For reasons explained the supply of additional pulses from the switch 97 to this counter is discontinued when the air temperature is below the value at which the thermostat 55 opens. In a modification, several thermostats operating at different temperatures are associated with separate switches 97 operated at different times by separate cam discs 105. The rate of supply of pulses thus decreases in steps as the temperature falls. The housing 11 and associated parts for operating the counter 72 may be used for comparing the thermal insulating properties of different materials used successively as insulation for the housing 11 which is, for this purpose, situated in a constant temperature enclosure.