| 摘要 |
PURPOSE:To contrive to improve the dredging efficiency by a method wherein the means of measurements made in response to the changes of rotational frequency and of velocity of flow are obtained and an arithmetic unit, which enables to automatically set a cavitation limit corresponding to said obtained means, is provided in order to allow to operate the pump with a margin smaller than usual to the set limit. CONSTITUTION:Analog signals N(t) and V(t) detected by an engine tachometer 1 and a current meter 2 respectively are digitized by an A/D converter 3 and brought by a computer 4. The means of the respective measurements are calculated after the repeated bringings-in of N(t) and V(t). Next, a cavitation limit corresponding to said means is obtained in accordance with the cavitation similarity rule. A cavitation limit HSVl is set as said caviation limit multiplied by a coefficient of beta1 and a target value HSVT to the cavitation limit to the cavitation limit is set as that multiplied by a coefficient of beta2. The limit HSVl and HSVT are inputted to a control device 6 in order to control the dredge pump. Because the cavitation limit is automatically set in such a manner as described above, the operation of the pump with the margin smaller than ever to said limit or the highly efficient operation of the pump becomes possible. |
