KR0123023B1 - Step attached axial inducer - Google Patents

Abstract

Pumps equipped with inducers used in conventional pumps, such as severe pressure pulsation, vibration, noise occurred in the suction pipe, and a number of proposals to improve this has been proposed as a Japanese patent, but these also have good production efficiency There were problems such as the increase of manufacturing cost due to the non-compliance, the occurrence of the imbalance of copper balance at the top of the inducer, the generation of pressure pulsation, noise and vibration over a wide operating range.

The present invention attaches a multiaxial blade to the front of the main impeller of the pump, forms an end portion so that the outer diameter of the front shaft is small, and extends from the pump casing and protrudes inward to the inner circumference of the cylindrical inlet portion surrounding the pump. By providing the end portion, it is a simple configuration to provide a device which reliably prevents the occurrence of pressure pulsation, noise and vibration even when applied to various pumps regardless of the design flow rate of the inducer.

Description

Stepped Axial Flow Inducer

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a sectional view showing the main parts of an embodiment of a stepped axial flow inducer according to the present invention;

2 is a sectional view showing the main parts of another embodiment of the stepped axial flow inducer according to the present invention;

* Explanation of symbols for main parts of the drawings

10: pump casing 10a: fluid intake port

12: axis of rotation 14: main impeller

16: Inducer 16a: front axial blade

16b: rear axial blade 18: end

20: abbreviation

This invention relates to the improvement of the axial flow inducer used for hydraulic machines, such as a pump, coaxially arrange | positioned at the front part of an impulse.

Background Art Conventionally, in hydraulic machines such as pumps, in order to significantly increase the suction performance of a fluid, a configuration in which an inducer is provided in front of the main impeller is known.

However, this type of inducer is a kind of high load axial impeller, for example, in a low flow rate range, it causes severe pressure pulsation in the pump suction pipe, and the pump operation is prevented by such a vibration and noise. It may become impossible.

Here, various measures to prevent such pressure drift have been proposed.

For example, 1: Japanese Patent No. 1139618 (Japanese Patent Application Laid-Open No. 57-32758) has drilled a plurality of holes in the upstream side of the inducer in which the area of the hole is smaller than the outside of the shaft center side of the pump. By arranging the throttle plate, there is disclosed a configuration that prevents the formation of backflow and prevents noise and vibration occurring in a low flow rate range.

Also, Japanese Patent No. 869739 (Japanese Patent Application No. 51-31681) has a bypass pipe that returns a part of the outlet flow of the inducer to the suction side. A configuration for avoiding is disclosed.

In addition, in Japanese Patent No. 952842 (Japanese Patent Application Laid-Open No. 53-30522), one end of the sleeve is fixed to the outermost circumference of the inducer, and the other end is bent inward to form a shortened portion, thereby vibrating. However, a configuration for preventing noise is disclosed.

Also, in Japanese Patent Application Laid-Open No. 58-5500, a passage for guiding the fluid toward the back and the surface of the wing is provided at the end of the fluid inlet of the inducer blade to improve the suction performance of the fluid. One configuration is disclosed.

However, according to the improved configuration for preventing the vibration and noise caused by the conventional inducer described above, each of the following problems has been encountered.

That is, according to the configuration of the above 1: the manufacturing efficiency is not good in the shape, dimensions, installation position, etc. of the reducing plate, when employing a desired general purpose pump, there is a difficulty in increasing the manufacturing cost. In addition, according to the configuration of the above 2: 2, there are difficulties as described above with respect to the flow rate to be bypassed, the opening position of the bypass pipe, and the like.

In addition, according to the configuration of 3 :, the effect of preventing vibration and noise is great, but since the sleeve is fixedly rotated at the tip of the inducer, it is possible to reduce the amount of unbalance in the balance at the outer periphery of the sleeve. There is a difficulty to be removed.

In addition, according to the configuration of the above 4: the effect of improving the pressure pulsation and noise is limited to the design flow rate, it is difficult to completely prevent the pulsation and noise generation in a general-purpose pump, such as a wide operating range.

As described above, the pressure pulsation and noise reduction measures in the conventional inducer have a lot of restrictions in their dimensions and shapes, and therefore, for example, in a general-purpose pump having a wide operating range, it is possible to consider the economical aspects. Inductors of various shapes and dimensions have been manufactured, but none are satisfactory.

Therefore, the object of the present invention is to provide a simple construction with a stepping process corresponding to each of the inlet portion of the inducer and the pump casing surrounding the inducer. The present invention also provides a stepped axial flow inducer that can prevent pressure pulsation and noise from occurring.

The stepped axial flow inducer according to the present invention coaxially arranges an inducer composed of multi-axial flow vanes at the distal end of a rotating shaft supporting the main impeller as a shaft, and the inducer extends in parallel with the rotating shaft. It is placed and disposed in the cylindrical suction port of the pump casing, the end portion is formed so that the outer diameter of the front axial blade located on the fluid suction side of the multi-axial blade of the inducer is small, and at the same time, the It is characterized by providing an end projecting inward to the inner circumferential portion of the cylindrical suction port portion.

In the above-mentioned stepped axial flow inducer, the outer diameter of the front axial blade is configured to be relatively smaller than the outer diameter of the rear axial blade, and protrudes inward to a portion of the cylindrical inlet portion of the pump casing corresponding to the front axial blade. A ring-shaped end approaching the outer edge may be provided to form a shortening portion for the rear axial blade.

Further, in the stepped axial flow inducer, the outer diameter of the front axial blade is made relatively smaller than the outer diameter of the rear axial blade, protrudes inward to a part of the cylindrical suction port of the pump casing corresponding to the front axial blade, and the front axial flow A ring-shaped end approaching the outer edge of the wing to form a first abatement for the rear axial blade, and a portion of the end provided in the cylindrical inlet of the pump casing corresponding to the top end of the inducer It may be configured to protrude inward to form a second shortening.

According to the stepped axial flow inducer according to the present invention, the end portion is formed so that the outer diameter of the front axial blade located on the fluid suction side of the multi-axial flow wing of the inductor is small, and correspondingly the inner peripheral portion of the cylindrical suction port portion Partial backflow can be suppressed between the rear axial blades of the inducer, and the reverse flow of fluid generated upstream of the rear axial blades with large outer diameter can be suppressed by the front axial blades and the shortening portion formed as the ends. have.

In addition, in the axial blade of the inducer, the fluid boosted by the rotation of the front axial blade having a small outer diameter and small circumferential speed is smoothly pumped toward the rear axial blade having a large outer diameter and large circumferential speed, so that the cavitation at the fluid inlet portion is reduced. It does not occur, and it can therefore reliably prevent the pressure pulsation and noise which occur with cavitation.

In addition, a part of the end provided in the cylindrical suction port of the pump casing corresponding to the uppermost end of the inducer is protruded inward to provide a second shortening portion, thereby effectively suppressing the backflow of fluid generated in the front axial blade having a small outer diameter. can do.

Therefore, in the case where the shortening portion is provided corresponding to the uppermost end of the inducer as described above, the outer diameter of the front axial blade can be made larger than in the case where there is no shortening portion, and the operating area of the pump is expanded.

Next, a typical embodiment of the stepped axial flow inducer according to the present invention will be described in detail with reference to the accompanying drawings.

1 is a sectional view showing the principal parts of a typical embodiment of the stepped axial flow inducer of the present invention. In FIG. 1, reference numeral 10 denotes a pump casing, and the pump casing 10 is provided with a main impeller 14 attached to the rotation shaft 12.

And the inducer 16 is coaxially arrange | positioned at the fluid suction side pressure part of this impeller 14.

In this case, the shaft blade of the inducer 16 shall be double or more.

In contrast, the fluid inlet 10a of the pump casing 10 surrounding the inducer 16 is configured in the form of a cylindrical tube parallel to the axis of the rotation shaft 12.

By the way, in this invention, with respect to the multiaxial flow wing of the said inducer 16, it protrudes inward to the inner peripheral part of the fluid suction part 10a of the pump casing 10 corresponding to the outer diameter of the front part axial flow wing 16a. And the end portion 18 of the ring shape approaching the outer edge of the front axial blade (10a) is fixedly arranged.

In this way, the end portion 18 forms a shortened portion with respect to the rear portion axial blade 16b having an outer diameter larger than the front portion axial blade 16a.

As can be clearly seen in the above-described embodiment, a ring-shaped end portion 18 is provided at the inner circumference of the fluid intake portion 10a of the pump casing 10 surrounding the inducer 16, and this end ( 18) by setting the outer diameter of the front axial blade 16a of the inducer 16 to be smaller than the outer diameter of the rear axial blade 16b, and inserting the front axial blade 16a into the end 18, The reverse flow of the fluid generated in the main impeller 14 part is suppressed to prevent partial back flow between the main impeller 14 and the axial blades of the inducer 16 adjacent to the main impeller 14 (particularly the rear axial blade 16b). The reverse flow of the fluid generated on the upstream side of the large rearward axial blade 16b can be suppressed by the reduction portion blooded to the front axial blade 16a and the end 18.

Further, in the axial blade of the inducer 16, the fluid pressurized by the rotation of the front axial blade 16a having a small outer diameter and a small circumferential speed is smoothly conveyed toward the rear axial blade 16b having a large outer diameter and a large circumferential speed. do.

By the way, when the outer diameter of the axial blade of the inducer 16 is large, when the suction condition is strict, the inlet outer peripheral portion of the inducer 16 usually generates a severe cavitation flow, but the inducer 16 as in this embodiment By providing a substantial step at the outer diameter of the axial blade of the blade), the fluid is elevated to the pressure portion axial blade 16a corresponding to the inlet side of the inducer 16 at the portion of the rear axial blade 16b having a large outer diameter. Since it is pressurized, even if the circumferential speed of this rear part axial blade 16b increases, such cavitation does not generate | occur | produce, Therefore, the pressure pulsation and noise which arise with cavitation can be prevented.

2 is a sectional view showing the main parts of another embodiment of the stepped axial flow inducer of the present invention.

Since the basic structure of this embodiment is almost the same as the embodiment of FIG. 1 described above, the same components are denoted by the same reference numerals, and detailed description thereof will be omitted.

Thus, in the present embodiment, the innermost portion of the fluid inlet portion 10a of the pump casing 10 corresponds to the uppermost end of the front axial blade 16a corresponding to the inlet side of the inducer 16. A part of the ring-shaped end part 18 protrudes inward as shown in FIG. 2, and the 2nd shortening part 20 is provided.

By configuring in this way, the backflow of the fluid which arises in the front part axial blade 16a with a small outer diameter can be suppressed effectively.

Therefore, according to this embodiment, the outer diameter of the front axial blade 16a can be made larger than the above-described embodiment, and the operating area of the pump can be enlarged.

As is apparent from the above-described embodiment, according to the present invention, an end portion is formed on the multiaxial blade of the inducer so that the outer diameter of the front axial blade located on the fluid suction side is made smaller, and correspondingly the cylindrical By providing the end which protrudes inwardly in the inner peripheral part of a suction port part, the reverse flow of the fluid which generate | occur | produces downstream of the inducer can be reliably prevented from propagating to the fluid suction pipe side located upstream.

Moreover, this backflow prevention effect is effective over the entire flow range despite the design flow rate of the pump, and can completely prevent the generation of noise during pump operation.

That is, in the present invention, since the fluid sucked into the front axial blade with a small outer diameter is boosted and then flows into the rear axial blade with a large outer diameter, cavitation is not generated at the axial blade with a large outer diameter. The occurrence of noise is prevented.

According to the present invention, the fluid introduced into the rear axial blade having a large outer diameter is axial flow blade having a small outer diameter by an end provided integrally with the inner peripheral part of the suction port of the pump casing with respect to the front axial blade portion having the small outer diameter. It becomes impossible to flow back to the part, forcibly recycles within the range in which the axial blades with large outer diameters are located, and it is possible to reliably prevent fluid vibration (pulsation) in the fluid suction pipe.

In addition, by corresponding to the most end of the front axial blade corresponding to the inlet side of the inducer, by protruding inward a part of the ring-shaped end provided in the inner peripheral portion of the fluid suction port portion of the pump casing inwards, It is possible to effectively suppress the backflow of the fluid generated in the front axial blade 16a, and to increase the outer diameter of the front axial blade, and to enlarge the operating region of the pump.

Furthermore, according to the present invention, it is only required to apply end-stage processing for constituting end portions at the inlet portions of the inducer and the pump casing, respectively, and the structure is very simple and easy to manufacture, and regardless of the design flow rate of the inducer It can be usefully applied to hydraulic machines such as pumps of various capacities.

As mentioned above, although the preferred embodiment of this invention was described, this invention is not limited to the above-mentioned embodiment, For example, it is not only applicable effectively to the inducer pump which consists of an inducer alone, but also the shape and structure of an end part. It is needless to say that many modifications can be made to the present invention, and that various design changes can be made without departing from the spirit of the present invention.

Claims (1)

The conduit inducer is arranged coaxially and separated from the main impeller at the distal end of the rotating shaft supporting the main impeller, and the outer diameter of the front part of the multi-axial flow wing is relatively smaller than the rear diameter of its rear part, and its small diameter A first row of large diameter rear axial wings, protruding inwardly to the inner surface of the pump casing surrounding the front axial blades of the ring and approaching the outer edge of the small diameter front axial blades Forming an impingement, and forming a ring-shaped end portion projecting inwardly of the pump casing cylindrical inlet portion corresponding to the foremost end of the small-diameter forward axial blade, thereby providing a second reduction portion for the small-diameter forward axial blade. Stepped axial flow inducer, characterized in that.

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