| 摘要 |
PURPOSE:To make it possible to charge kneading material so as to employ the power of the driving motor of a mixer efficiently for any kneading amount by a method wherein the load current value of the driving motor of the mixer is detected at the charging of kneading material, especially of gravel so as to open or close a charging gate in response to the load current value. CONSTITUTION:The load current value of the driving motor 2 of a two-shaft type concrete mixer is detected by a current detection circuit 3 and compared by a comparator 4 with the set points, which have been respectively set in advance at an upper limit current setter 5 and at a lower limit current setter 6. Then the load current value at the charging of kneading material is smaller than the lower limit current set point, a signal, which actuates to open the charging gate 8 of a gravel metering tank 7, is sent from the comparator to an on-off controller 9 so as to continuously charge gravel. When the load current value becomes larger than the upper limit current set point, a signal, which actuates to close the charging gate 8 of gravel, is outputted from the comparator 4 to the on-off controller 9 so as to stop the charging of gravel. A timer is provided for the case that the load current value exceeds the upper limit current set point due to the temporary and short-time load rise caused by the encroaching of gravel or the like so as to be able to close the charging gate 8 only when the load current value, which exceeds the upper limit current set point, is held for a period of time longer than the certain value. |
