| 摘要 |
PURPOSE:To suppress a pressure drop of jetted liquid by detecting internal pressure of an accumulator, calculating a rate of change of the internal pressure, and applying a load to a pump when the internal pressure reaches below a set pressure between an upper limit and a lower limit set values. CONSTITUTION:An accumulator 7 is installed via high pressure water feed piping on a discharge side of a pump 6. A plurality of nozzle headers 3-5 are connected via a plurality of jet valves 8-10 to a midway part of the high pressure water feed piping. A pressure sensor 12 for detecting internal pressure of the accumulator 7 is arranged, and based on a detection signal thereof the pump 6 is loaded or unloaded by a control device 13 so as to control pressure of high pressure water jetted from the respective nozzle headers 3-5. A rate of change of detected internal pressure is calculated in the control device 13. When the rate of change is not less than a set value and also the internal pressure reaches below a set value between an upper limit and a lower limit set values, the pump 6 is loaded. |
