JP2017048704A - Impeller and axial flow blower including the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an impeller and an axial flow blower that generate less vibration and can obtain high reliability.SOLUTION: An impeller 3 comprises: a plurality of blades 4 radially provided on an outer peripheral surface of a cup-shaped boss member 5; and aluminum plates 9 partially provided on surfaces of the blades 4.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an impeller and an axial fan provided with the impeller.

  An axial blower may generate a large vibration during operation at a specific rotation speed (rotational speed). This is a resonance phenomenon caused by the fact that the resonance frequency that the impeller of the axial flow fan has as an eigenvalue matches the operating frequency of the axial flow fan. In the case of a propeller-type impeller, the influence of resonance is particularly significant because the blade is cantilevered.

  As an industrial propeller type impeller, a metal plate having blades attached to a boss is generally used. As such an impeller, a welding impeller obtained by welding a blade to a boss portion, and a rivet type impeller in which a blade is riveted to the boss portion are known. In particular, since the thickness of each blade in the welding impeller is uniform, the stress acting on the blade mounting portion tends to increase due to the large amplitude at the time of resonance. If the stress acting on the blade attachment portion increases, the blade may be damaged.

  For this reason, conventionally, the axial blower has been adjusted to the design of the motor and the like according to the thickness of the blades so that it can be operated at an operating frequency that avoids the resonance frequency.

  In recent years, with increasing awareness of energy saving, there is an increasing demand for variable speed operation that reduces power consumption by changing the operating frequency of an axial blower by inverter control or the like and reducing the rotational speed of the motor as much as possible. In this case, since the operating frequency is set to various values by the user, it is necessary to consider use in a wide range of operating frequencies. If the operating frequency is changed over a wide range, the possibility of overlapping with the resonance frequency of the blades increases. In this case, abnormal vibration and excessive stress are generated due to a resonance phenomenon, and the reliability of the product is significantly lowered.

  For example, Patent Document 1 discloses a blower in which an inclusion having a vibration damping function is mounted between a fan and a fan cap that fixes the fan to a rotor. Patent Document 2 discloses an axial blower in which abnormal vibration of the blade is suppressed by partially providing a steel plate on the surface of the blade. In the axial blower described in Patent Document 2, the resonance frequency is shifted by increasing the natural frequency by partially increasing the thickness of the blade.

JP-A-4-203296 Japanese Patent Laying-Open No. 2015-086803

  The blower described in Patent Document 1 is a fan in which an excitation force applied to a fan due to vibration generated from a rotor is simply reduced by mounting inclusions, and the fan has a wide operating frequency range. No consideration is given to the suppression of resonance.

  In the axial blower described in Patent Document 2, since the weight of the steel plate installed on the blade is relatively large, if the thickness of the steel plate is increased to adjust the natural frequency, the centrifugal force generated when the impeller rotates. Strength increases. In this case, the stress generated in the root portion of the blade becomes excessive, and the reliability of the product is lowered due to the damage of the blade.

  An object of the present invention is to provide an impeller and an axial blower that can generate high reliability with less occurrence of abnormal vibration.

  A preferred embodiment of the impeller according to the present invention includes a plurality of blades radially provided on the outer peripheral surface of the cup-shaped boss member, and an aluminum plate partially provided on the surface of the blade. It is characterized by.

  A preferred embodiment of the axial blower according to the present invention includes the impeller according to the above-described embodiment and an electric motor that rotationally drives the impeller.

  According to the present invention, it is possible to realize an impeller and an axial blower that can generate high reliability with less occurrence of abnormal vibration.

It is the side view and front view of an impeller which concern on Example 1, and an axial-flow fan provided with the same. It is AA sectional drawing of FIG.1 (b). It is a top view which shows the structure of the conjugate | zygote of the braid | blade and aluminum plate which are installed in the impeller which concerns on Example 2. FIG. It is a top view which shows the structure of the conjugate | zygote of the braid | blade and aluminum plate which are installed in the impeller which concerns on Example 3. FIG. It is a top view which shows the structure of the conjugate | zygote of the braid | blade and aluminum plate which are installed in the impeller which concerns on Example 4. FIG.

Hereinafter, examples will be described with reference to the drawings.
FIG. 1 shows an impeller of Example 1 and an axial blower provided with the impeller. FIG. 1A is a side view with a partial cross section, and FIG. 1B is a front view.

  In FIG. 1, 1 is an electric motor (motor), 2 is a rotating shaft, 3 is an impeller, 4 is a blade (blade), 5 is a boss member, 6 is a hub member, 7 is a washer (washer), 8 is a bolt, 9 Is an aluminum plate.

  The electric motor 1 is an induction motor that is driven at a variable speed by, for example, a VVVF (variable voltage variable frequency) inverter power supply. doing.

  Although not shown in FIG. 1, the impeller 3 is covered with a casing provided with a substantially cylindrical member called a duct or a shroud, and the electric motor 1 is held in the casing.

  The impeller 3 is configured such that a plurality of blades 4 (for example, eight in FIG. 1) are provided radially on the outer peripheral surface of a substantially cup-shaped boss member 5. At the center of the boss member 5, a thick-walled short cylindrical hub member 6 is installed. The hub member 6 is for attaching the impeller 3 to the rotary shaft 2, and after the through hole at the center of the hub member 6 is fitted to the rotary shaft 2, the hub member 6 is inserted from the outside of the hub member 6 through the washer 7. The impeller 3 is attached to the rotating shaft 2 by tightening the bolt 8 to the rotating shaft 2.

  The blade 4 is formed of a metal plate, for example, a steel material. A blade formed of steel can obtain a large air volume and a high static pressure as compared with a general household ventilation fan provided with, for example, a resin blade. Moreover, by using a steel plate blade, it is possible to obtain sufficient durability against a use environment such as a use temperature when it is installed in equipment such as a factory or a vehicle body.

  Next, the impeller 3 will be described in detail. FIG. 2 is a cross-sectional view taken along line AA in FIG.

  The blade 4 is formed, for example, by stamping a steel plate into a predetermined planar shape by press working, so that the entire blade 4 has a substantially constant thickness. The aluminum plate 9 is formed to be shorter than the blade 4, and after being superimposed on the blade 4, it is joined to the blade 4 by laser welding or spot welding, for example. Thereby, the joined body 10 in which the aluminum plate 9 is partially joined to the blade 4 is obtained. The joined body 10 is formed into a predetermined curved surface shape by pressurization.

  The aluminum plate 9 is a plate formed mainly of aluminum. In the examples, “mainly consisting of aluminum” means containing 90% or more of aluminum. As the aluminum plate 9, for example, a plate material formed according to JIS A5052P can be used.

  The boss member 5 is formed by pressing a steel material into a cup shape. The blade 4 is welded to the outer peripheral surface of the boss member 5. In the first embodiment, the welding impeller in which the blade 4 is welded to the boss member 5 has been described as an example. However, the present invention is not limited to the welding impeller, and for example, a rivet in which the blade 4 is riveted to the boss member 5. It may be a type impeller.

  The feature of the first embodiment is that an aluminum plate 9 is joined to the blade 4 and adjusted so as to increase its natural frequency. A numerical value that is an integral multiple of the natural frequency is the resonance frequency.

The natural frequency f is generally expressed as the following formula (1) in relation to the weight M and the spring constant K.
f = √ (K / M) (1)

  When the formula (1) is applied to the blade 4 of the impeller 3, the spring constant K corresponds to the ease of twisting or bending of the blade 4. That is, the spring constant K increases as the blade 4 is less likely to be twisted or bent, and therefore, the spring constant K increases as the thickness of the blade 4 increases. As shown in the equation (1), the increase of the spring constant K works in the direction of increasing the natural frequency f. On the other hand, when the blade 4 is thickened, the weight M of the blade 4 itself increases. The increase in the weight M works in the direction of lowering the natural frequency f. Therefore, in order to increase the natural frequency f of the blade 4, it is necessary to prevent the blade 4 from being twisted or bent and to suppress an increase in weight.

  In the first embodiment, the thickness of the blade 4 is substantially increased by partially joining the aluminum plate 9 to the blade 4. Thereby, the spring constant K can be increased while suppressing an increase in the weight M as the joined body 10. For this reason, the natural frequency f of the joined body 10 can be increased, the resonance frequency can be shifted to a range higher than the variable range of the operating frequency of the axial flow fan, and the resonance phenomenon can be avoided.

  In the first embodiment, an aluminum plate 9 mainly composed of aluminum having a relatively small specific gravity is used as a plate to be joined to the blade 4. Thereby, for example, an increase in the weight M when the plate thickness is increased can be suppressed as compared with a case where a steel plate plate mainly composed of a steel material having a specific gravity greater than that of aluminum is used. That is, by joining the aluminum plate 9, the plate thickness can be increased to increase the spring constant K as the joined body 10, and a significant increase in the weight M as the joined body 10 can be suppressed. Therefore, for example, the plate thickness can be easily adjusted as compared with the case where a steel plate is used, and the natural frequency f can be adjusted in a wider range.

  Moreover, the aluminum plate 9 is low-cost, and an increase in manufacturing cost can be suppressed. Moreover, since the aluminum plate 9 has a melting point close to that of a blade mainly made of steel, for example, welding can be easily performed.

  Since the aluminum plate 9 and the blade 4 are separate members before joining, the thickness of each plate is appropriately adjusted in accordance with the purpose and environment of use of the axial blower within a range in which the resonance phenomenon can be avoided. Can be joined.

  For example, by increasing the thickness of the aluminum plate 9 (for example, about 2.3 mm or more), the spring constant K as the joined body 10 can be increased, and the thickness of the blade 4 is decreased (for example, about 2.3 mm). ), The increase in the weight M as the joined body 10 can be suppressed.

  In addition, the operating frequency of the axial flow fan is changed by inverter control, etc., and the rotational speed of the motor is reduced as much as possible to increase the demand for variable speed operation that suppresses power consumption. Considering that the resonance frequency is generally a low frequency when installed in a housing and operating, the resonance phenomenon is likely to occur at a low frequency. For this reason, it is desirable to avoid moving the natural frequency of the joined body 10 of the blade 4 and the aluminum plate 9 in the lower direction.

  In the example shown in FIG. 1B, the aluminum plate 9 has a front edge portion 12 and a rear edge of the blade 4 at a boundary portion between the blade 4 and the boss member 5 (hereinafter referred to as a root portion 11 of the blade 4). The blade 4 extends in the radial direction along a center line 14 passing through an intermediate position with the portion 13. Thereby, stability of rotation of the impeller 3 provided with the joined body 10 can be maintained.

  As described above, the aluminum plate 9 is formed to have a constant width shorter than the blade 4 with the center line 14 of the blade 4 as the center, and from the root portion 11 of the blade 4 to the tip portion in the radial direction of the blade 4. It is extended to 15.

  That is, the aluminum plate 9 is installed starting from a position separated from the center of the boss member 5 by the same distance as the outer diameter (for example, 100 mm or more) of the boss member 5, and from the center of the boss member 5 to the impeller. 3 is extended to a position separated by the same distance as the outer diameter of 3 (for example, 200 mm or more). By installing the aluminum plate 9 from the root portion 11 to the tip portion 15 of the blade 4, the joined body 10 is hardly twisted and bent, and the spring constant K is increased.

  Further, by installing the aluminum plate 9 by a certain width around the center line 14 of the blade 4, an increase in the weight M as the joined body 10 is suppressed. Thereby, the natural frequency f as the joined body 10 can be increased.

  In FIG. 1A, when the impeller 3 rotates, the air flow direction of the wind generated by the impeller 3 changes from the right side to the left side in FIG. In this case, the wind pressure received by the downstream surface of the blade 4 in the ventilation direction is higher than the wind pressure received by the upstream surface. For this reason, if the aluminum plate 9 is joined to the downstream surface in the ventilation direction, the pressure fluctuation increases and noise may increase.

  By joining the aluminum plate 9 to the surface of the blade 4 on the upstream side in the ventilation direction, an increase in noise can be suppressed.

  According to the axial blower 100 of the first embodiment, by joining the blade 4 and the aluminum plate 9, the natural frequency f as the joined body 10 is increased, and the resonance frequency is shifted to a range that does not coincide with the operation frequency. be able to. For this reason, it is possible to suppress abnormal vibration due to a resonance phenomenon during variable speed operation and generation of excessive stress accompanying this. Moreover, according to the axial-flow fan 100 of Example 1, the increase in the weight can be suppressed, changing the resonant frequency as the conjugate | zygote 10. FIG. For this reason, when the impeller 3 rotates, an increase in stress due to the centrifugal force generated in the root portion 11 of the blade 4 and the accompanying damage to the blade 4 can be suppressed. For this reason, high reliability can be obtained while responding to energy saving awareness.

  The impeller according to Example 2 will be described below. The second embodiment is different from the first embodiment in that the shape of the aluminum plate is changed. Other basic configurations of the impeller and the axial flow fan are the same as those of the first embodiment. This point is the same in Examples 3 to 4.

  FIG. 3 shows a configuration of the joined body 20 of the blade 24 and the aluminum plate 29 installed in the impeller according to the second embodiment. FIG. 3 shows the configuration of one of the plurality of joined bodies 20 (blades 24), and the same applies to FIGS.

  The aluminum plate 29 according to the second embodiment is formed to be shorter than the blade 24, and extends from the root portion 22 of the blade 24 (the boundary portion between the blade 24 and the boss member 25) along the center line 21 of the blade 24. The blade 24 extends in the radial direction to a predetermined length. That is, the aluminum plate 29 is installed so as not to reach the tip of the blade 24.

  By installing the aluminum plate 29 from the root portion 22 of the blade 24, the joined body 20 can be made difficult to twist. Further, by installing the aluminum plate 29 so as not to reach the tip of the blade 24, an increase in the weight M as the joined body 20 can be suppressed.

  The axial flow fan of Example 2 including the joined body 20 shown in FIG. 3 increases the weight M as the joined body 20 while changing the resonance frequency as the joined body 20 to a range that does not coincide with the operating frequency. It can suppress more efficiently. For this reason, an increase in stress due to the centrifugal force generated in the root portion 22 of the blade 24 during the rotation of the impeller can be more efficiently prevented while suppressing abnormal vibration due to a resonance phenomenon during variable speed operation. Can do.

  The impeller according to Example 3 will be described below. FIG. 4 shows the configuration of the joined body 30 of the blade 34 and the aluminum plate 39 installed in the impeller according to the third embodiment.

  The aluminum plate 39 of the third embodiment is formed to have a width substantially equal to the width from the front edge portion 31 to the rear edge portion 32 of the blade 34, and the root portion 33 (the blade 34 and the boss member 35 between the blade 34 and the boss member 35). From the boundary portion), the blade 34 extends in the radial direction to a predetermined length. That is, the aluminum plate 39 is installed so as not to reach the tip of the blade 34.

  By installing the aluminum plate 39 from the root portion 33 of the blade 34, the joined body 30 can be made difficult to twist. Further, when the aluminum plate 39 is formed to have a width substantially equal to the width from the front edge portion 31 to the rear edge portion 32 of the blade 34, for example, when the thickness of the blade 34 is reduced, the joined body 30 as a whole is formed. The aluminum plate 39 can be adjusted so that the strength of the steel plate does not decrease.

  The impeller according to Example 4 will be described below. FIG. 5 shows a configuration of the joined body 40 of the blade 44 and the aluminum plate 49 installed in the impeller according to the fourth embodiment.

  When the impeller rotates, the stress generated in the root portion 43 of the blade 44 increases in the region on the front edge 41 side of the blade 44. In the aluminum plate 49 of the fourth embodiment, the stress generated in the root portion 43 of the blade 44 when the impeller rotates, that is, the region on the front edge portion 41 side of the blade 44, from the root portion 43 of the blade 44, It extends to a predetermined length in the radial direction. That is, in the fourth embodiment, the aluminum plate 49 is installed on the front edge portion 41 side of the blade 44 and is not installed on the rear edge portion 42 side of the blade 44.

  As a result, the joined body 40 is less likely to be twisted or bent, and the weight of the joined body 40 can be reduced. For this reason, the natural frequency f of the joined body 40 can be increased, and abnormal vibration due to a resonance phenomenon when the variable speed operation is performed can be suppressed. Further, the weight reduction of the joined body 40 can suppress an increase in stress generated in the root portion 43 of the blade 44 when the impeller rotates, and can prevent the blade 44 from being damaged.

  The impeller and axial blower described above can be suitably used, for example, for in-vehicle use. Moreover, it can also be used for ventilation of equipment in a factory or the like, for example, other than in-vehicle use.

DESCRIPTION OF SYMBOLS 1 ... Electric motor, 2 ... Rotating shaft, 3 ... Impeller 4, 24, 34, 44 ... Blade (blade) 5, 25, 35 ... Boss member, 6 ... Hub member, 7 ... Washer (washer), 8 ... Bolt, 9, 29, 39, 49 ... Aluminum plate, 10, 20, 30, 40 ... Assembly, 11, 22, 33, 43 ... Blade root portion, 12, 31, 41 ... Blade front edge, 13 , 32, 42 ... rear edge of blade, 14, 21 ... center line of blade, 15 ... tip of blade, 100 ... axial blower

Claims (8)

A plurality of blades provided radially on the outer peripheral surface of the cup-shaped boss member;
An aluminum plate partially provided on the surface of the blade;
Impeller characterized by having.   The impeller according to claim 1, wherein the blade is made of a steel material.   The impeller according to claim 1, wherein the blade is welded to the boss member.   The aluminum plate extends in a radial direction of the blade along a center line passing through an intermediate position between a front edge portion and a rear edge portion of the blade at a boundary between the blade and the boss member. The impeller according to claim 1, wherein the impeller is characterized.   5. The impeller according to claim 4, wherein the aluminum plate extends from a boundary between the blade and the boss member to a tip portion of the blade in a radial direction of the blade.   2. The impeller according to claim 1, wherein the aluminum plate extends on a front edge side of the blade from a boundary with the boss member of the blade in a radial direction of the blade.   2. The impeller according to claim 1, wherein the aluminum plate is provided on a surface of the blade on the upstream side in a ventilation direction of wind generated by rotation of the blade. The impeller according to any one of claims 1 to 7,
An axial blower comprising: an electric motor that rotationally drives the impeller.

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