| 摘要 |
<p>1,251,510. Burner control systems. COMBUSTION ENG. Inc. 24 Dec., 1968 [27 Dec., 1967], No. 61490/68. Heading F4T. [Also in Division G1] Apparatus for testing the working of a flame detector such as an ultra-violet sensitive tube in a burner control system includes means for simulating a no-flame condition, such as an electromagnetically operated shutter to shield the tube from radiation, and a check circuit to sample the output of the detector after a predetermined interval provided by a timer such as a unijunction timer 38 and provide a signal, commensurate with that output, to which indicating means is responsive, the shutter being opened again after a predetermined period. The apparatus includes a rotary switch 10 operated by a timing mechanism such as a clock and output pulses therefrom are applied to an OR gate 12 and to a pair of AND gates 14, 22, 16, 24, 18, 26 or 20, 28. The OR gate 12 applies a signal to a pulse generator 30 which may be a monostable multivibrator and its output pulse is applied to the set input terminals of bi-stable multivibrator 32, 34 which results in output signals from bi-stable 32 to disable a timing circuit 36 and energize a timing circuit 38. Circuit 36 comprises a free running oscillator which, except when it is disabled by a signal of the proper polarity at the set output terminal of bi-stable 32 will provide a series of pulses to the reset input of bi-stable 34 so that generation of a pulse by generator 30 will switch bi-stable 34 this multivibrator not being reset until after timing circuit 36 has been released by the resetting of bi-stable 32. The reset output terminal of bi-stable 34 is connected to the input of selector AND gates 22, 24, 26, 28 so that the gate provided with a signal by switch 10 will be opened to provide a signal to one of checking circuits 40, 42, 44, 46 and the bi-stable is also connected to a primary driver 48, which may be an amplifier, the output of which is applied to shutter AND gates 50, 52, 54, 56. Accordingly an output signal at one of the master switch output terminals causes closing of a shutter in front of the selected device, the current for energization of the shutter being supplied by amplifier 48. Malfunction is indicated by an alarm.</p> |
