JPS5968582A - Automatic setting device of cavitation limit of dredge pump - Google Patents

Abstract

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.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic cavitation limit setting device for a dredging pump.

In conventional cutter dredgers, when the swing speed is automatically controlled, the cavitation limit is set constant regardless of the pump rotation speed and flow rate. Therefore, since it is necessary to set the pump rotation speed and flow rate under the most severe conditions, it is necessary to set it at a low value with some margin.

Therefore, it has not been possible to increase dredging efficiency with conventional cutter dredgers.

The present invention has been proposed in view of the above circumstances, and an object of the present invention is to provide an automatic cavitation limit setting device for a dredging pump that can significantly improve dredging efficiency by reducing the margin of cavitation limit as much as possible.

The cavitation limit automatic setting device for a dredging pump according to the present invention includes an instrument for measuring the rotational speed and flow velocity of the dredging pump, and an average of the measured values according to changes in the pump rotational speed and flow velocity measured by the instrument. It is characterized by being equipped with a calculation unit and a metal fitting for determining the cavitation limit corresponding to the average value.

An embodiment of the present invention will be described in detail based on the drawings.

FIG. M1 is a block diagram showing a schematic configuration of the i embodiment of the present invention, and FIG. 2 is a flowchart showing the operation of the embodiment shown in FIG.

In Figure 1, C', 5 is the pump tachometer, 2 is the flow rate side, 3
4 is a computer (computation unit), 5 is a cavitation limit automatic setting device, and 6 is a control device.

The operation of the embodiment of the present invention will be explained based on FIGS. 1 and 2. Analog signals N(t→ and V (t) Ha A/D
Converter 3 VCL re-digitization and computer 4
be taken into account. This operation is repeated several times, and N(t) and V(t) at the past several measurement points are
Calculate the average of each g+++ constant value. Next, find the cavitation limit corresponding to the average value of N(t) and V(t) according to the similarity law of cavitation characteristics.0 Multiply the above cavitation limit by the coefficient of β1 to obtain the cavitation limit ■Isvg0 or β2. The coefficients are then set as the cavitation limit target value H3VT. Here, each of the above coefficients β and β2 are coefficients to provide a margin for the calculated value, for example, 1>β1>β2
(For example, β+=0.8.β2=0.6) are set in advance and input into the computer 4. The thus divided cavitation limit HBv and cavitation limit target value IHsv'r are input to the control device 6, and the dredging pump is controlled by the control device 6.

As described above, according to the present invention, the cavitation characteristics of the pump are calculated as following the theoretical similarity law with respect to changes in the pump rotation speed and flow rate, and the cavitation limit 5' ? 't,
rSince it can be set automatically, you can save more money than before.
In addition, an excellent effect of efficient dredging operation can be obtained. Note that the above calculations can be performed continuously at high speed by using a computer.

In short, according to the present invention, there is provided an instrument that measures all the rotational speed and flow velocity of a dredging pump, and an average value of the measured values is determined according to changes in the pump rotational speed and flow velocity measured by the instrument, and the average value corresponds to this average value. The present invention provides an automatic cavitation limit setting device for a dredging pump that can significantly improve dredging efficiency by reducing the allowance for cavitation limits as much as possible by incorporating a calculation unit that calculates cavitation limits. Above all, it is extremely useful.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a schematic configuration of an embodiment of the present invention, and FIG. 2 is a flowchart showing the operation of the embodiment shown in FIG. ... Velocity meter, 3... A/D converter, 4... Computer (
Calculating unit), 5... Cavitation limit automatic setting device, 6... Control device 0 Applicant sub-agent Patent attorney Takehiko Suzue Figure 1 Continued from page 1 Inventor Hidehiko Sakuragi Kannon, Nishi-ku, Hiroshima City Inside the Mitsubishi Heavy Industries, Ltd. Hiroshima Research Center, 4-6-22 Shinmachi 0 Inventor: Kazuko Takeshita Inside the Mitsubishi Heavy Industries, Ltd. Hiroshima Research Center, 4-6-22 Kannon Shinmachi, Nishi-ku, Hiroshima City

Claims (1)

[Claims] An instrument that measures the rotational speed and flow rate of the dredging pump, and a calculation unit that calculates the average of the measured values according to changes in the pump rotational speed and flow rate measured in the side group, and calculates the cavitation limit corresponding to this average value. An automatic cavitation limit setting device for a dredging pump characterized by comprising: