JPH0441990A - Supercavitating pump - Google Patents

Abstract

PURPOSE:To form an impeller blade of a movable blade being automatically adjustable in a specified opening against a suction level and hence to obtain a high suction performance with a low pump input power by holding the impeller blade at as specified opening based on a suction level detected with a water gage. CONSTITUTION:Water in a suction tank is sucked from a suction port by an impeller 2, and is then discharged from a discharge pipe 4 through a guide impeller 3. In this case, a suction level Hs in the suction tank is detected with a water gage 12, and its signal is transmitted to a minicomputer 13. Meanwhile, the optimal opening beta for an impeller blade against the suction level Hs is stored in the minicomputer 13. The minicomputer 13 is operated to compare a stroke St based on a signal from an opening gage 14 with the opening beta. Then, based on a signal from the water gage 12, a signal St is transmitted to an electric motor adapted for changing the stroke St of an arm 10 in such a manner that the impeller blade corresponds to the optimal opening beta. Consequently, the impeller blade is usually held at the optimal opening beta. Thus, it is possible to obtain a high suction performance with a low drive force and hance to perfrom an economical operation.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a super cavity cheating pump that is applied in cases where high suction performance is required.

[Conventional technology]

The impeller of a conventional super cavity cheating pump has fixed blades, and unlike a general impeller, it has a suction head (suction head) (when the rotation speed is n and the flow rate is Q without a sudden drop in the total head below sv). Suction specific speed S=n・Q””/H,v”
The suction performance expressed by ' is high, and the total head is suction head H3
%l decreases (lower water absorption level), and is operated while generating cavitation at the limit point, and the flow rate and total head at that limit point are the design specification points.

[Problem to be solved by the invention]

FIG. 3 is a performance curve diagram of the conventional super cavity cheating pump as described above. In the figure, the dotted line represents the characteristics when the suction head HSV is at the design specification, and the impeller has a large angle of attack so as to satisfy the flow rate and total head at the design specification point at this suction head HffV. Therefore, the suction head) 1sv is larger than the design specification (if the water suction level is sufficiently high, the maximum efficiency point will move to a flow rate larger than the design specification point, as shown by the solid line, and the total head will also increase). This makes it uneconomical, as it requires extra shaft power that is greater than the design specifications.

[Means to solve the problem]

The super cavitating pump according to the present invention aims to solve the above problems, and includes an impeller whose blade opening degree changes, a water level meter that detects the water absorption value of the impeller, and a water level meter that detects the water absorption value of the impeller. and a means for holding the blade at a predetermined opening degree.

[Effect]

That is, in the super cavity cheating pump according to the present invention, the blades of the impeller are held at a predetermined opening degree based on the water absorption value detected by the water level needle,
If the impeller blades are fixed blades, operation can only be done with a high total lift, but by making the impeller blades movable, which automatically adjusts to a predetermined opening according to the water absorption value, it is possible to operate with low shaft power. High suction performance can be obtained.

〔Example〕

FIG. 1 is a structural explanatory diagram of a super cavity cheating pump according to an embodiment of the present invention, and FIG. 2 is an explanatory diagram of its operation. In the figure, the super cavity cheating pump according to this embodiment is a chamber shaft type and is used for pumping water.
As shown in the figure, the water in the suction tank is pumped through the suction port l by the impeller 2.
It is sucked in from the air, passed through the guide vanes 3, and then discharged from the discharge pipe 4.

The impeller 2 of the super cavity cheating pump differs from a general impeller in that the suction head F (the total head does not suddenly decrease below sv, and the total head is the suction head) decreases by 1sv (reduction in water absorption value). As a result, it is gradually decreasing, and it is being used at its breaking point. Therefore, if the water absorption value is sufficiently high, the impeller blades can satisfy the flow rate and total head at the design specification point with a smaller opening. The impeller of this pump is arranged so that the impeller can be operated by changing the opening degree of the impeller according to the increase or decrease of the suction head Hiv.
, crosshead 7, intermediate shaft 8, and other link mechanisms. The intermediate shaft 8 passes through the main shaft and reaches the top of the electric motor (not shown), where it is connected by a pin 11 to an arm 10 supported by a fulcrum 9. By raising and lowering the tip of the arm 10, the blades of the impeller 2 can be opened. As the degree changes, the stroke St at the tip of the arm 10 is detected by the opening degree gauge j4. The water absorption value Hs in the suction tank is determined by water level gauge 1.
2, and the signal is sent to the minicomputer I3. Minicomputer 13 has its water absorption value Hs
The optimum opening degree β of the blades of the impeller 2 is stored, and the stroke St and the opening degree β are compared based on the signal from the opening meter 14, and the impeller 2 is adjusted based on the signal from the water level gauge 12. A signal S is sent to an electric motor that changes the stroke St of an arm 1° (not shown) so that the blades of the impeller 2 match the optimal opening β, forming a system that always maintains the blades of the impeller 2 at the optimal opening β. There is. Note that various other mechanisms are conceivable for maintaining the blades of the impeller 2 at the optimal opening degree β.

FIG. 2 is a cavitation characteristic diagram when the flow rate of this pump is constant. When the suction head H3V is large (high water absorption value C), the blade opening β to obtain the required total head
has a small opening C and requires less shaft power. When the water absorption value decreases, the necessary total head cannot be obtained with the opening degree C, but the blade automatically changes to the opening degree B, which is slightly larger than the opening degree C. However, since the total head characteristic also decreases due to the influence of cavitation, the shaft power remains almost unchanged.

When the water absorption value further decreases to a water absorption value a, the blade has a larger opening degree A. Even so, like the opening degree B, the shaft power is large (does not increase).In this way, as the suction head H5V changes, the total head, efficiency, and shaft power each move in the direction of the arrow shown by the dotted line. Therefore, if the blades of the impeller 2 are fixed blades with the opening degree A, operation can only be performed with a high total head, but if the blades are made movable, the blades of the impeller 2 will automatically adjust to the optimum value for the water absorption value Hs. By providing a mechanism with the opening degree β, it is possible to obtain high suction performance up to the water absorption value a with low shaft power.In addition, according to test results using a model, the shaft power is 70% and the suction performance is 1.4 times higher. became.

[Momme of invention]

The super cavity cheating pump according to the present invention is configured as described above, and high suction performance can be obtained with low shaft power, so that it can be operated economically.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a super cavitating bomb according to an embodiment of the present invention, FIG. 2 is an explanatory diagram of its operation, and FIG.
The figure is an explanatory diagram of the operation of a conventional super cavitating bomb. 1... Suction port, 2... Impeller, 3... Guide vane, 4... Discharge pipe, End... Arm, 6...
Link, 7...Crosshead, 8...Intermediate shaft, 9
...Fully point, 10...Arm, 11...Bin, 12...Water level gauge, 13...Mini computer, 14
...Opening degree gauge. Agent: Patent attorney Akira Sakama and 2 other people #11 country

Claims (1)

[Claims] It is characterized by comprising an impeller whose blade opening degree changes, a water level gauge that detects the water absorption level of the impeller, and means for maintaining the blade at a predetermined opening degree based on the detected value of the water level meter. Super cavitating pump.