JP4467041B2 - Centrifugal fan - Google Patents

Description

  The present invention relates to a centrifugal fan suitable for office automation equipment, home appliances, and the like.

  A fan that attaches an impeller to a rotor of a motor and rotates the impeller includes a centrifugal fan that sucks air along an axis of the motor and exhausts it in a radial direction perpendicular to the axis. The centrifugal fan can discharge a high static pressure air flow, and is suitable for an application that needs to supply a high static pressure air flow to a specific part. In recent years, this centrifugal fan is required to rotate with lower noise and vibration than ever before.

  FIG. 5 shows a centrifugal fan conventionally used. An impeller b of the centrifugal fan a has a cylindrical cup part c having an opening at the bottom and a lid part at the top, and a lower part of the cup part c. A gap d extending in the radial direction from the outer peripheral surface of the end of the rim, a surface on the upper side of the flange d, and a position spaced from the outer peripheral surface of the cup part c are spaced apart in the circumferential direction. And a plurality of blade portions e extending upward, and integrally injection-molded with a synthetic resin. A rotation shaft f projects downward from the center of the cup portion c. The motor g that rotationally drives the impeller b has a configuration that is accommodated inside the cup portion c and a configuration that is disposed outside the cup portion c by further extending the rotation shaft f.

  In order to suppress such vibration and noise of the centrifugal fan, it is necessary to further improve the rotation balance of the impeller. As the rotational balance is made to coincide with the center of gravity of the rotating body and the center of rotation, the whirling of the rotating body becomes smaller. Since a rotary body such as an impeller that is injection-molded involves molding errors, it is difficult to mold them by matching them. For this reason, the unbalance is usually corrected by attaching a weight that cancels out the rotational balance of the rotating body.

  For example, a method for attaching a weight to an impeller (see Patent Documents 1 and 2), a mold that can be used for forming an impeller so that the balance can be corrected, and after the impeller is completed, the balance is corrected and the weight is attached to the work. There is a known technique (see Patent Document 3).

When these known methods are applied to the centrifugal fan 2 shown in FIG. 5, the methods disclosed in Patent Documents 1 and 2 are insufficient in the degree of coincidence between the center of gravity of the impeller and the rotation center and do not have a significant balance correction effect. It was. In addition, the weight must be attached to each impeller, and the productivity is not good.
Although the method of Patent Document 3 improves the productivity problems as in Patent Documents 1 and 2, no significant balance correction effect was found.

  As another known technique for improving the balance correction effect, Patent Document 4 discloses a technique in which weights are arranged on a plurality of surfaces separated in the axial direction. When this technique was applied to the centrifugal fan, a weight on one surface could be provided inside the cup portion as in Patent Document 3, but a portion for arranging another weight could not be found. For example, as shown in FIG. 1 of Patent Document 3, it is conceivable to attach a weight in the vicinity of the lower end of the cup portion. However, significant improvement in balance is not achieved, and productivity is reduced in terms of weight mounting work. It was not good.

Japanese Utility Model Publication No. 63-98498 JP 2000-184678 A Japanese Patent No. 2931044 JP-A-6-284666

  As a problem to be solved, various methods for improving the rotation balance of the motor are known. However, there has been no centrifugal fan that rotates more stably than before by applying them to the centrifugal fan.

  The solution of the present invention with respect to the above problems is a cylindrical cup portion having one open side and the other side having a lid portion, and a flange portion extending radially outward from the outer peripheral surface of one end portion of the cup portion, A plurality of blade portions provided on the other surface of the flange portion and at positions spaced from the outer peripheral surface of the cup portion, extending in the circumferential direction and extending to the other side. In the centrifugal fan in which the impeller is integrally formed by injection molding, a balance adjusting portion is provided on each of the lid portion of the cup portion and the flange portion, and these balance adjusting portions are integrally formed at the time of the impeller molding. It is characterized by that.

  The balance adjustment part of the lid part or the collar part has an annular convex part protruding in an axial direction on an annular surface concentric with the rotation center as a mold relating to the molding of the lid part or the collar part. By removing the specific area of the part, the mold is formed using a mold for forming irregularities having different thicknesses on the circumference of the lid part or the collar part.

  In addition, the balance adjustment part of the lid part or the collar part is a mold related to the molding of the lid part or the collar part, and includes a plurality of sections that are divided in the circumferential direction and arranged equally on an annular surface that is concentric with the rotation center. And forming by using a mold for forming irregularities having different thicknesses on the circumference of the lid portion or the collar portion by projecting or denting a part of the plurality of sections.

  The balance adjustment portion on the lid portion side of the cup portion can be provided on one surface of the lid portion. In addition, the balance adjustment portion on the heel portion side can be provided on one surface of the heel portion.

  In the centrifugal fan of the present invention, the balance is adjusted so that the center of gravity of the impeller and the center of rotation coincide with each other on two surfaces separated in the axial direction, so that the balance is extremely small and low vibration and low noise are realized. . In particular, since the balance adjustment portion on one surface is located at the collar portion of the impeller, the balance correction effect is large. And since the balance adjustment part is integrally provided at the time of shaping | molding of an impeller, the productivity of an impeller is good.

  The best mode for carrying out the centrifugal fan of the present invention will be described with reference to FIGS. FIG. 1 is a cross-sectional view showing the centrifugal fan, FIG. 2 is a bottom view of the impeller of FIG. 1 as viewed from the bottom to the top, and FIG. 3 is a cross-sectional view of a principal part showing a modification of the impeller of FIG. FIG. 4 is a perspective view showing a main part of a mold for manufacturing the impeller shown in FIG.

  A centrifugal fan 2 shown in FIG. 1 includes a motor 20 inside an impeller 10, which is housed in a housing 30. When a current flows through the stator 21 of the motor 20, a rotating torque is generated on the driving magnet side by the magnetic action with the driving magnet 22, and the impeller 10 rotates. When the impeller 10 rotates, the air in the upper part of the housing 30 is sucked into the housing 30 from the upper side to the lower side of the axis via the intake port 31a of the housing 30, and is sucked into the impeller 10 and discharged radially outward. It is. The discharged air flows in the circumferential direction along the side surface of the housing 30 and is exhausted from the exhaust port 31b.

  The housing 30 is a combination of a bottom member 32 (referred to as a bottom frame) that supports the motor 20 and a top member 33 (referred to as a top frame) that covers the impeller 10 together with the bottom frame 32. The cavity which accommodates the motor 20 in the inside is formed. An intake port 31 a is formed near the center of the upper surface side frame 33. An exhaust port 31 b is formed on the side surface surrounding the periphery of the impeller 10 by the bottom surface side frame body 32 and the top surface side frame body 33.

  In the motor 20, a stator 21 is fixed together with a circuit board (not shown) on an outer peripheral surface of a cylindrical portion 34 provided so as to protrude upward in the center of the bottom surface side frame 32. Bearing means 36 is accommodated on the inner peripheral surface of the cylindrical portion 34 and rotatably supports the rotary shaft 14. An impeller 10 is provided at the upper end of the rotating shaft 14. A driving magnet 22 disposed on the impeller 10 so as to face the outer peripheral surface of the stator 21 is fixed via a back iron 23.

  The impeller 10 is injection-molded integrally with a metal rotating shaft 14 by a synthetic resin using a mold described later. More specifically, a covered cylindrical cup portion 11 having an open lower end portion, a flange portion 12 extending radially outward from an outer peripheral surface of the lower end portion of the cup portion 11, There are dozens of blade portions 13 provided on the upper surface and at a position spaced apart from the outer peripheral surface of the cup portion 11 by extending in the circumferential direction and extending upward. Yes. At the center of the ceiling wall (lid part) of the cup part 11, the upper end part of the rotating shaft 14 is embedded and protrudes to the vicinity of the lower end part of the cup part 11.

  Further, a first balance adjustment unit 15 is provided on the outer peripheral part of the lower surface of the ceiling wall of the cup part 11, and a second balance adjustment part 16 is provided on the outer peripheral part of the lower surface of the flange part 12. Yes.

  The first balance adjusting portion 15 is formed in a circular shape with a thick portion 15a whose thickness is larger than that of the other portions on the outer peripheral portion of the ceiling wall, and a plurality of depressions 15b are formed by deleting a part of the thick portion 15a. It is composed by doing. As shown in FIG. 2, the recess 15b is formed in 13 consecutive sections among a plurality of sections divided into 16 equal intervals in the circumferential direction. The thick portion 15a is located in the range of about 65 degrees clockwise from the reference point S at the periphery. Thereby, on the outer periphery of the ceiling surface in the cup part 11, thickness differs on the circumference by the thick part comprised by the thick part 15a, and the thin part comprised by the 13 depressions 15b. Concavities and convexities are formed, and the impeller 10 is configured so that a weight is applied to the thick portion side of the cup portion ceiling wall.

  On the other hand, the second balance adjustment unit 16 is configured by forming a recess 16a over a range of about 330 degrees at the periphery of the lower surface of the flange 12 (the periphery of the range of about 30 degrees other than the recess is Make up the thick part with the other surface.) The thick portion is located in a range of about 30 degrees counterclockwise from the position of about 60 degrees counterclockwise from the reference point S described above. As a result, irregularities having different thicknesses are formed on the circumference of the periphery of the collar portion 12 by a portion having the same thickness as other portions and a thin portion having a small thickness due to the recess 16a. A weight is applied to the thick portion side of the collar portion 12.

  That is, the surface passing through the upper side of the rotating shaft 14 of the impeller 10 is given a predetermined weight in a range of about 60 degrees clockwise from the reference point S by the first balance adjusting unit 15, and passes through the lower side of the rotating shaft 14. A predetermined weight acts on the surface in a range of about 30 degrees counterclockwise from a point rotated about 60 degrees counterclockwise from the reference point S by the second balance adjusting unit 16. Thus, the impeller 10 as a whole has a configuration in which the deviation of the center of gravity of the impeller is offset by combining weights that individually act on the two surfaces at both ends in the axial direction. As a result, the center of gravity of the impeller and the center of rotation almost coincide with each other by compensating for the deviation of the center of gravity of the impeller, which could not be corrected by the balance adjustment unit on one side alone, so that the center of gravity of the impeller almost coincides with the rotation center. Is extremely small. Therefore, since the centrifugal fan 2 provided with the impeller 10 rotates stably with little swing, low vibration and low noise are realized. In addition, the second balance adjusting portion 16 is exposed to the outside of the impeller 10 and has a undulation formed in the circumferential direction thereof, but does not protrude from the lower surface of the flange portion 12, so There is almost no squealing noise.

  Note that the positional relationship and distribution ratio between the thick and thin portions in the first and second balance adjusting sections 15 and 16 change depending on various conditions such as the shape of the impeller, the material, and the mold used for molding. This example is one form. Further, as shown in FIG. 3, the lower end portion of the cup portion 11 has a configuration in which the outer diameter gradually increases on the lower side (part indicated by reference symbol A), or the upper end portion of the cup portion 11 is rounded. (Part B), the air passing through the gap formed between the blade part 13 and the cup part 11 by setting the inner diameter side of the upper end of the blade part 13 as a round (part C part). Flows smoothly and the air blowing characteristics can be improved.

  Next, a method for manufacturing the impeller 10 will be described.

  As the mold, a plurality of molds corresponding to the impeller 10 are used, and these are combined to place a rotating shaft 14 in a gap formed between the molds and filled with molten synthetic resin. After the synthetic resin is solidified, the impeller 10 is formed by extracting the solidified synthetic resin portion from both molds.

  For example, a mold 50 shown in FIG. 4 is used as the mold corresponding to the inner surface of the cup portion 11 of the impeller 10 and the lower surface of the flange portion 12 among the plurality of molds. The first balance adjusting portion 15 is formed using the cylindrical portion of the mold 50. Sixteen balance pins 50a are provided at equal intervals in the circumferential direction on the outer peripheral portion of the upper surface of the cylindrical portion of the mold 50, and the upper end of the balance pin 50a can be protruded or recessed in the axial direction. Moreover, it has the structure which has the through-hole 50c which inserts the rotating shaft 14 in the center of a cylindrical part. Further, the second balance adjusting portion 16 is formed using a disk-like portion located below the cylindrical portion of the mold 50. The disc-shaped portion of the mold 50 is provided with a convex portion 50b that protrudes somewhat upward on the upper surface of the outer peripheral portion.

  A plurality of molds including molds corresponding to the parts of the mold 50 and the other impeller 10 are used in order to determine the first and second balance adjusting units 15 and 16 described above in the manufacturing stage of these molds. The impeller 10 is prototyped in a state where all the balance pins 50a are protruded and the convex portions 50a are annular. The impeller 10 molded in this state is applied to a balance inspection device to measure the unbalance amount. As a result, if the unbalance amount is within an allowable range, it is used as it is as a formal mold.

  On the contrary, if it is out of the allowable range, the weight and the position necessary for canceling the unbalance amount are measured, and the balance pin 50a of the mold 50 is retracted correspondingly (in this example). The mold is adjusted by scraping off a part of the balance pin 50a ′) in the drawing and a part of the convex portion 50a (in this example, a portion indicated by symbol E in the drawing). The portion of the balance pin 50a 'is filled with a greater amount of synthetic resin, so that the balance pin 50a' is formed thicker than other balance pins 50a. Similarly, the portion indicated by the symbol E of the convex portion 50a is filled with a large amount of synthetic resin, and thus is thicker than the other convex portions 50a that are not cut. In other words, in the molding site corresponding to the circumference where the balance pins 50a are arranged and the circumference where the convex portions 50a are provided, irregularities having different thicknesses are formed on the circumference, and the thick portion is heavier in mass.

  The impeller 10 is prototyped again using the mold thus adjusted. The impeller 10 molded in this state is again applied to the balance inspection device, the unbalance amount is measured, and the quality is determined. The mold is adjusted by repeating such a series of steps. The mold thus obtained can form an impeller with very little deviation with the center of gravity substantially coincident with the center of rotation. In addition, since the balance of the impeller is corrected at the mold stage, after adjustment of the mold, work such as performing a balance inspection or attaching a weight after molding is unnecessary, and the productivity of the impeller 10 is good.

  The centrifugal fan 2 has a configuration in which the balance of the balance is extremely small as described above, but this is not only that the balance adjusting units 15 and 16 are positioned on the upper and lower surfaces of the impeller 10, The effect | action by the 2nd balance adjustment part 16 being located in the collar part 12 of the impeller 10 is large. That is, since the thick part of the second balance adjusting unit 16 is located on the outer peripheral part of the impeller 10, the rotational moment here is increased, and the balance correction effect by the weight provided at this position is great.

  Moreover, since the 2nd balance adjustment part 16 is located in the collar part 12, it can provide collectively at the time of the shaping | molding of the impeller 10 with the 1st balance adjustment part 15, and productivity is good.

  Although the best mode of the present invention has been described above, the scope of the present invention is not limited to this, and various modifications can be made without departing from the spirit of the present invention. For example, the mold 50 is used for forming the first balance adjusting unit 15, but a part of the mold may be shaved and molded like the second balance adjusting unit 16, or the second balance adjusting unit 15 may be formed. 16 may be molded using a mold 50. Further, the first balance adjustment unit 15 may be formed on the upper surface side of the lid portion of the cup unit 11, and the second balance adjustment unit 16 may be formed on the upper surface of the collar unit 12, for example, with the adjacent blade 13. It may be in a portion between the blades 13.

It is sectional drawing which shows the best form which concerns on the centrifugal fan of this invention. It is the top view which looked at the impeller of FIG. 1 from the downward side. It is principal part sectional drawing which shows the modification of the impeller of FIG. It is a perspective view which shows a part of metal mold | die for manufacturing the impeller of FIG. It is sectional drawing which shows the conventional centrifugal fan.

Explanation of symbols

DESCRIPTION OF SYMBOLS 2 Centrifugal fan 10 Impeller 11 Cup part 12 Gutter part 13 Blade | wing part 15 1st balance adjustment part 16 2nd balance adjustment part

Claims (5)

A cylindrical cup portion having one side open and a lid on the other side;
A flange extending radially outward from the outer peripheral surface of one end of the cup;
A plurality of blade portions provided on the other side surface of the flange portion and at positions spaced from the outer peripheral surface of the cup portion, extending in the circumferential direction and extending to the other side. In the centrifugal fan in which the impeller is integrally injection-molded,
A centrifugal fan, wherein a balance adjustment portion is provided on each of the lid portion of the cup portion and the flange portion, and these balance adjustment portions are integrally formed when the impeller is molded.   The balance adjustment part of the lid part or the collar part has an annular convex part protruding in an axial direction on an annular surface concentric with the rotation center as a mold relating to the molding of the lid part or the collar part. 2. The centrifuge according to claim 1, wherein the centrifuge is formed using a mold that forms irregularities having different thicknesses on the circumference of the lid portion or the collar portion by deleting a specific region of the portion. fan.   The balance adjustment part of the lid part or the collar part has a plurality of sections which are divided as a mold related to the molding of the lid part or the collar part by being equally arranged in the circumferential direction on an annular surface concentric with the rotation center. The mold is formed by using a mold for forming irregularities having different thicknesses on the circumference of the lid part or the collar part by projecting or indenting a part of the plurality of sections. The centrifugal fan according to claim 1.   The centrifugal fan according to any one of claims 1 to 3, wherein the balance adjustment portion of the lid portion of the cup portion is provided on one surface of the lid portion.   The centrifugal fan according to any one of claims 1 to 3, wherein the flange-side balance adjusting portion is provided on one surface of the flange.

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