| 摘要 |
<p>57 For belt conveyors in which the loaded part of the belt is supported by a gas layer in a through, the energy needed to drive the belt is lower if the belt is more fully out of contact with the trough. But much energy is needed to compress the gas carrying the belt. The invention proposes to provide means to measure the power for these two purposes and to alter the gas flow into the trough so that the total power requirement is at a minimum. The latter may be performed in steps and as soon as a step appears to result in an increase of power required, this step may be undone. Drives of the belt (1) and of a compressor (6) by electric motors (5, 8) make measurement of electric power supplied thereto preferable. A control member (14) receives signals of power measurements and issues signals to change the power for drive of the compressor. Instead of separate measurements added by the control member (14) the latter may be fed with a measurement of the total power supplied for both purposes. For long conveyor belts there may be more than one compressor and more than one electric motor for moving the belt, in which case, together with the control of the compressors, one or more of such drive motors may be switched on or off to keep the operating motors at high efficiency.</p> |
