JPH10184589A - Mixed flow pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent any increase in driving force even if a gap narrowing member is brought into slide-contact with the inner face of a suction casing and prevent any clogging of foreign matters in liquid in a gap by fixing the gap narrowing member made of a flexible material to the tip of a blade rotated in the vicinity of the inner face of a casing or a casing liner. SOLUTION: A gap narrowing member 20 for narrowing a gap between the tip of a blade 3 of an impeller 1, i.e., a portion which is rotated in the vicinity of the inner face of a suction casing 11 and the inner face of the suction casing 11 is fixed to that portion. The gap narrowing member 20 is made of a flexible material which is low in frictional resistance when it is brought into slide-contact with the inner face of the suction casing 11, is excellent in abrasion resistance and is easily flexible, such as rubber. Consequently, during operation of a mixed flow pump, it is possible to reduce a quantity of liquid leaking at the gap between the gap narrowing member 20 and the inner face of the suction casing 11. Furthermore, even if the gap narrowing member 20 is brought into slide-contact with the inner face of the suction casing 11, any damage can be prevented because of low friction resistance and sufficient abrasion resistance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a mixed flow pump.

[0002]

2. Description of the Related Art An example of a conventional mixed flow pump is shown in FIG. In FIG. 3, reference numeral 1 denotes an impeller, which comprises a hub 2 and a plurality of blades 3 planted around the hub 2 at equal intervals in the circumferential direction. Reference numeral 4 denotes a main shaft, which comprises an upper shaft 5, a lower shaft 6, and a shaft coupling 19 for connecting these. Reference numeral 8 denotes a casing, a discharge bowl 9 and a discharge casing 10 connected to the upper end thereof.
And a suction casing 11 connected to the lower end thereof.

[0003] The hub 2 of the impeller 1 is wedge-fitted to the lower end of the lower shaft 6 via a key 7, and the impeller nut 8 is connected to the lower shaft 6.
The impeller 1 is attached to the lower shaft 6 by screwing into the lower end of the shaft.

The lower shaft 6 is rotatably supported by a submerged bearing 14 supported in a bearing case 13 via a sleeve 12 fixed to an intermediate portion thereof. Bearing case 13 is a support plate
The cone 16 is fixed to a cone 16 via a plurality of stays 17 and is supported by the discharge bowl 9 via a plurality of stays 17.

When the main shaft 4 is driven by a motor (not shown), the impeller 1 rotates, and the liquid is sucked through the suction casing 11 and is urged by the blades 3. Then, the liquid is discharged through a discharge channel 18 and a discharge casing 10 formed between the discharge bowl 9 and the cone 16.

[0006]

In the above-mentioned mixed flow pump, the impeller 1 is moved by the temperature change occurring during the operation or the movement of the impeller 1 by the radial thrust and the axial thrust.
A predetermined gap is set between the suction casing 11 and the tip thereof so that the tip does not contact the inner surface of the suction casing 11. However, if the gap is increased, the amount of liquid leaking from the gap increases, and the performance of the mixed flow pump is increased. However, there was a problem that was reduced.

[0007]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and its gist is that the tip of a blade rotating close to the inner surface of a casing or a casing liner is provided. The mixed flow pump has a gap narrowing member made of a flexible material fixed thereto.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention is shown in FIG. A gap narrowing member 20 for narrowing a gap with the inner surface of the suction casing 11 is provided at a tip portion of each blade 3 of the impeller 1, that is, a portion that rotates near the inner surface of the suction casing 11.
Is fixed.

As shown in FIG. 1 (B), the gap narrowing member 20 has a sharp tip, a base having the same thickness as the blade 3, and a support base 21 projecting from the center of the base. And a stopper 32 which has a circular cross section formed at the tip thereof and which has the same shape as the above and is engaged with an engaging portion 31 formed at the tip of the blade 3 and abuts against both end surfaces of the stenosis member 20. Screw 33
Is attached to the blade 3 by fastening to the blade 3.

As shown in FIG. 2A, the locking portion 22 can be formed in a rectangular shape, and as shown in FIG. 2B, one end of the blade 3 is cut off. The base end of the stenosis member 20 which is thinner than the blade 3 can be fitted into the shoulder 34 formed by the above-mentioned method, and directly fastened by the set screw 35.

The gap narrowing member 20 has a low frictional resistance when it comes into sliding contact with the inner surface of the suction casing 11, has a high abrasion resistance, and can be easily bent.
It can be made of a flexible material such as rubber, synthetic resin, or a fine brush. The other configuration is the same as that of the conventional one shown in FIG. 3, and the corresponding members are denoted by the same reference numerals and description thereof will be omitted.

During the operation of the mixed flow pump, the amount of liquid leaking from the gap between the distal end of the gap narrowing member 20 and the inner surface of the suction casing 11 is reduced.
That is, the total head and NPSH (effective suction pressure) can be improved.

Further, even if the gap narrowing member 20 slides on the inner surface of the suction casing 11 due to the movement of the impeller 1 due to a temperature change, a shaft thrust, a radial thrust, or the like, the gap narrowing member 20 has a small frictional resistance, Since it is rich in abrasion, it is not damaged and does not increase the driving power of the mixed flow pump.

Further, even if a foreign substance is contained in the liquid, the gap narrowing member 20 bends and allows the foreign substance to pass through the gap without being clogged.

Although the present invention has been described with reference to the case where the present invention is applied to a vertical mixed-flow pump, the present invention can be applied to a horizontal mixed-flow pump shown in FIG. In this case, the tip of the blade 41 of the impeller 40 rotates close to the inner surface of the casing ring 43 embedded in the inner surface of the casing.

When the present invention is applied to the vertical spiral mixed flow pump shown in FIG. 5, the tip of the blade 51 of the impeller 50 rotates close to the inner surface of a casing ring 53 installed inside the spiral casing 52. .

[0017]

According to the present invention, the gap between the tip of the blade and the inner surface of the casing or casing liner can be narrowed by the gap narrowing member to reduce the amount of liquid leaking from this gap. Performance can be improved.

Further, even if the impeller moves due to a temperature change, an axial thrust, a radial thrust, or the like, even if the gap narrowing member slides on the casing or the inner surface of the casing liner, the gap narrowing member bends without being damaged. There is no need to increase the driving power of the flow pump.

Furthermore, even if foreign matter is contained in the liquid, the foreign matter can be passed through the gap narrowing member without being clogged by bending.

[Brief description of the drawings]

1A and 1B show a first embodiment of the present invention, wherein FIG. 1A is a longitudinal sectional view of a main part, and FIG. 1B is a partially enlarged sectional view taken along line BB of FIG. 1A.

FIGS. 2A and 2B are partially enlarged cross-sectional views corresponding to FIG. 1B, each showing another embodiment of the present invention.

FIG. 3 is a cross-sectional view of a conventional vertical mixed flow pump.

FIG. 4 is a sectional view of a conventional horizontal-axis mixed flow pump.

FIG. 5 is a cross-sectional view of a conventional vertical swirl mixed flow pump.

[Explanation of symbols]

 11 Casing 1 Impeller 3 Blade 20 Gap narrowing member

Claims (1)

[Claims] 1. A mixed flow pump wherein a gap narrowing member made of a flexible material is fixed to a tip of a blade rotating close to an inner surface of a casing or a casing liner.