| 摘要 |
<p>905,764. Automatic temperature-control systems. RANCO Inc. May 13, 1960 [May 13, 1959], No. 16934/60. Class 38 (4). In an automatic temperature-control system for a heating element 10, an alternating current supply from terminals L1, L2 to the element is controlled by a switch 12 actuated by a hot-wire 18. The hot-wire is energized from lines L2, L3 through a step-down transformer 30 and a switch 22 having a contact mounted on a bi-metallic member 24 and a contact mounted on a frame 25. The member 24 carries a heating coil 27 on a leg 24a energized through a resistor 34, sensing the temperature of element 10, a a coil 28 on leg 24b, energized through rheostats 40, 43, and a coil 29 on leg 24b energized in series with the hot-wire 18. At low element temperatures the resistance of resistor 34 is low and the deflection of arm 24a due to coil 27 is greater than the opposing deflection due to coils 28, 29 so that the switch 22 remains closed and the element 10 is fully energized. At a pre-determined temperature the deflection due to coil 27 is reduced below that due to coils 28, 29 so that switch 22 are opened and coil 29 and the hot-wire 18 are deenergized. The temperature is maintained constant at the desired temperature by the opening and closing of the switch 22 under the action of coil 29. The rheostat 43 is manually adjusted by a dial 16 to set the desired temperature and the rheostat 40 is pre-set to adjust the boil-rate calibration.</p> |
