JP2006042489A - Axial fan - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make good use of a back yoke made of a sheet metal, that is used in combination with a permanent magnet, for adjusting the rotation balance, in an axial fan. <P>SOLUTION: A rotor 8 includes the cylindrical permanent magnet 6 and the back yoke 7 made of a sheet metal. The back yoke 7 includes a cylindrical plate portion 71 and a circular plate portion 72. Rotational balance adjusting portions 9, protruded inside the permanent magnet 6, are continuously formed on the inner radius portion of the the circular plate portion 72. The rotation balance adjusting portions 9 are partitioned in multiple bendable inwardly protruded pieces 91, by dividing portions 10 composed of notches or slits. The space S encircled with the rotation balance adjusting portions 9 is formed of the sheet metal material already punched for forming the back yoke 7. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an axial fan, and more particularly to an axial fan in which measures are taken to adjust the rotational balance during the assembly process.

  In machinery equipped with a rotating part such as a motor or an axial fan, the rotation balance adjustment work of the rotating part is performed during the assembly process, so that noise is generated due to poor rotation balance and the service life is impaired. To prevent it from happening. Various countermeasures for adjusting the rotation balance have been proposed (Patent Documents 1 to 6).

  The countermeasure proposed in Patent Document 1 is to cut off the protrusion provided on the rotating part of the motor, and the countermeasure proposed in Patent Document 2 is the protrusion provided on the rotating part of the axial flow fan. These are common in that they cut off the protrusions. Further, the countermeasure proposed in Patent Document 3 is to attach a balance weight to the rotating portion of the permanent magnet motor, and the countermeasure proposed in Patent Document 4 is put in the gap formed in the rotating portion. These are common in that they use a weighting substance such as a balance weight or putty.

  Furthermore, in the countermeasure proposed in Patent Document 5, a cylindrical hub, which is a rotating portion of the axial fan, is formed as a synthetic resin molded body, and a part of the hub is cut away so that the dynamic balance of the rotor (rotational balance) is achieved. Is adjusted. Further, Patent Document 5 describes that the rotor of the axial fan includes a permanent magnet, a back yoke that overlaps the outer surface of the permanent magnet and the end surface in the axial direction thereof.

  Furthermore, in Patent Document 6, a balance adjusting member is attached to each of the upper and lower portions of the rotating sleeve to which the rotating polygon mirror is attached, and the strip-shaped portions provided in a plurality of circumferential directions of the balance adjusting member are bent to rotate the balance. It is described to correct.

On the other hand, conventionally, for example, in a small axial fan used for cooling an electric device such as a DVD drive, a balancer (weight) equipped with an impeller is separately attached to a rotating part as a measure for adjusting the rotational balance, molybdenum, etc. Such an adhesive containing a high specific gravity material is applied to the rotating part, or a part of the rotating member is directly cut by cutting.
JP 11-299191 A JP 2003-113798 A JP-A-10-271863 JP 2004-15871 A Japanese Patent Laid-Open No. 11-223195 JP-A-6-160755

  However, the measures proposed in Patent Document 1 and Patent Document 2 require a protrusion to be provided separately on the rotating portion, so that not only the structure becomes complicated, but also the cutting operation of the protrusion is troublesome. The measures proposed in Patent Document 3 and Patent Document 4 may increase the cost because a substance that becomes a weight has to be used separately. This point may be caused by using a balancer (weight) or an adhesive with a high specific gravity material. The same applies to the conventional example used. Furthermore, since the countermeasure proposed in Patent Document 5 is to partially cut a cylindrical hub made of a synthetic resin molded body, the cutting work is troublesome. The same applies to the conventional example in which the material is directly scraped off. Furthermore, since the countermeasure proposed in Patent Document 6 requires a separate balance adjusting member to be attached to the rotating sleeve, the number of parts increases and the cost increases accordingly.

  The present invention has been made under the above circumstances, and is disclosed by the above-mentioned Patent Document 5 without adding any new parts when adjusting the rotational balance during the assembly process of the axial fan. An axial fan that can adjust the rotational balance properly by simply bending a part of a sheet metal part formed integrally with the back yoke. The purpose is to provide.

  Another object of the present invention is to provide an axial fan capable of accurately adjusting the rotational balance based on the measurement result obtained by the rotational balance measuring instrument.

  In the axial fan according to the present invention, the rotor that drives the impeller includes a permanent magnet, a sheet metal back yoke that overlaps the outer surface of the permanent magnet and the end surface in the axial direction thereof. And the rotation balance adjustment part which comprises the annular plate piece part which protrudes inside the permanent magnet and can be bent partially is provided in the inner peripheral part of the overlapping part with the axial end surface of the permanent magnet of the back yoke. Has been. If it is this structure, the center-of-gravity position of a rotation part will change only by bending partially the rotation balance adjustment part which consists of an annular plate piece part made from sheet metal. For this reason, it is possible to adjust the rotation balance by a tube end operation simply by bending the sheet metal portion. In particular, according to the present invention, the rotation balance adjusting portion is an annular plate piece portion continuously provided on the inner peripheral portion of the overlapping portion with the axial end surface of the permanent magnet of the back yoke made of sheet metal originally provided in the axial fan. Therefore, it is not necessary to provide the rotation balance adjusting unit as a separate part. Therefore, there is no possibility that the number of parts increases and the cost increases.

  In the present invention, the rotation balance adjusting portion is formed at a plurality of circumferential positions of the rotation balance adjusting portion, and a plurality of inwardly projecting pieces that can be bent by a split portion having slits or slits having start ends at the inner peripheral edges thereof. It is desirable to be divided into According to this, when the rotation balance adjusting part is partially bent, the influence of the bending does not easily reach a portion other than the bent portion, and the accuracy of the rotation balance adjustment can be easily improved. In other words, when one arbitrary portion of a plurality of inwardly projecting pieces is bent, the situation that the other inwardly projecting pieces are deformed by the influence of the bending does not occur, and it becomes easy to improve the accuracy of the rotation balance adjustment. .

  In the present invention, the permanent magnet has a cylindrical shape, and the back yoke has a cylindrical plate portion that overlaps the outer surface of the permanent magnet, and an axial end surface of the permanent magnet that protrudes inward from one end of the cylindrical plate portion. It is possible to employ a configuration in which the rotation balance adjusting section is connected to the circular plate portion.

  An axial fan according to the present invention is an axial fan in which a rotor that drives an impeller includes a permanent magnet and a sheet metal back yoke that overlaps an outer surface of the permanent magnet and an axial end surface thereof. The permanent magnet has a cylindrical shape, and the back yoke has a cylindrical plate portion that overlaps the outer surface of the permanent magnet, and a circular shape that protrudes inward from one end of the cylindrical portion and overlaps the axial end surface of the permanent magnet. And a rotation balance adjustment unit composed of an annular plate piece projecting inside the permanent magnet is connected to the inner periphery of the circular plate unit, and the rotation balance adjustment unit is connected to the balance adjustment unit. Is divided into a plurality of inwardly projectable pieces that can be bent by a split portion formed by a slit or a slit formed at a plurality of circumferential directions of the portion and having a start end at the inner peripheral edge thereof, and is taken by the rotation balance adjusting portion. Enclosed space is formed by punching trace of sheet metal material for forming the back yoke is further embodied by adopting the structure that. In the present invention, in particular, the space surrounded by the rotation balance adjusting portion is formed by the punching trace of the sheet metal material for forming the back yoke, so the back yoke is rotated. There is an advantage that the size of the punched waste material is reduced as compared with the conventional case when the balance adjusting unit and the sheet metal material are integrally manufactured. This point will be described in more detail with reference to embodiments described later.

  As described above, the axial fan according to the present invention uses a back yoke that is used in combination with a permanent magnet to prevent magnetic leakage of the permanent magnet, and the back yoke is provided inside the permanent magnet. Since the annular plate pieces projecting inward are connected and used as a rotation balance adjustment section, it is easy to adjust the rotation balance simply by partially folding the rotation balance adjustment section during the assembly process without adding parts. Will be able to do it. For this reason, it is possible to reduce the noise of the axial fan without incurring high costs, and to prevent the service life of the axial fan from being impaired. Further, in the case where the rotation balance adjusting section is partitioned into a plurality of inwardly projecting pieces, an effect is obtained that the rotation balance can be accurately adjusted based on the measurement result by the rotation balance measuring instrument.

  FIG. 1 is a longitudinal side view of an axial fan according to an embodiment of the present invention. 2 is a plan view of the main part showing the shape of the rotation balance adjusting unit 9, FIG. 3 is a plan view of the main part showing another shape of the rotation balance adjusting unit 9, and FIG. It is a top view of the principal part which showed other shape of these.

  The basic configuration of the axial fan will be described with reference to FIG. In the figure, reference numeral 1 denotes a housing, and 2 denotes a bearing sleeve attached to the housing 1, and an impeller 4 is attached to a rotating shaft 3 that is rotatably supported by the bearing sleeve 2. The impeller 4 is a synthetic resin molded body integrally provided with an impeller 41 and a cap-shaped hub 42. The housing 1 is provided with a stator 5 having a core 51 and a coil 52. On the other hand, a cylindrical permanent magnet 6 provided inside the hub 42 around the stator 5. Is deployed. A back yoke 7 made of sheet metal overlaps the outer surface of the permanent magnet 6 and the end surface in the axial direction. Therefore, in the axial fan having this configuration, the rotor 8 that drives the impeller 4 includes the permanent magnet 6 and the back yoke 7 made of sheet metal.

  The back yoke 7 serves to prevent the magnetic force of the permanent magnet 6 from leaking, and it has been well known that a magnetic circuit having a stable operation performance is formed by providing the back yoke. The back yoke 7 includes a cylindrical plate portion 71 that overlaps the outer surface of the permanent magnet 6, and a circular plate that protrudes inward from one end of the cylindrical plate portion 71 and overlaps the axial end surface of the permanent magnet 6. Conventionally, the circular plate portion 72 of the back yoke 7 does not protrude inside the axial end surface of the permanent magnet 6, or protrudes slightly even if protruding. It wasn't too much. Conventionally, even if the circular plate portion 72 of the back yoke 7 protrudes inside the axial end surface of the permanent magnet 6, it is impossible to adjust the rotational balance by bending the protruding portion. The idea itself of bending the protruding portion to adjust the rotational balance did not exist.

  Therefore, in this embodiment, the rotation balance adjusting portion 9 formed of an annular plate piece projecting inside the permanent magnet 6 is connected to the inner peripheral portion of the circular plate portion 72 of the back yoke 7. In FIG. 1, the inward projecting width from the end surface in the axial direction of the permanent magnet 6 of the rotation balance adjusting unit 9 is indicated by a symbol A. The inward projecting width A of the rotation balance adjusting unit 9 only needs to be formed to a size necessary and sufficient to partially bend and deform the rotation balance adjusting unit 9.

  In this way, if the rotation balance adjusting portion 9 that can be partially bent and deformed is connected to the inner peripheral portion of the circular plate portion 72 of the back yoke 7 in a continuous manner, the rotation balance is unsatisfactory. In such a case, if only a part of the rotation balance adjusting unit 9 is partially bent with reference to the measurement result by the rotation balance measuring instrument, the position of the center of gravity of the rotor 8 changes according to the position of the bent portion. Therefore, the rotation balance is adjusted accurately.

  By the way, in this embodiment, a circular space surrounded by the rotation balance adjusting unit 9 is formed by a stamping mark of a sheet metal material for forming the back yoke 7. On the other hand, in a back yoke employed in a conventional axial fan, a circular space surrounded by the circular plate portion is formed by a stamping trace of a sheet metal material for forming the back yoke. Therefore, even when the rotation balance adjusting portion 9 is formed on the back yoke 7 as in the embodiment or when the rotation balance adjusting portion 9 is not formed as in the prior art, a punching waste material is generated by punching the sheet metal material. Although the waste material is discarded, the size of the punching waste material that occurs when the rotation balance adjustment unit 9 is formed as in the embodiment is larger than the punching waste material that occurs when the rotation balance adjustment unit 9 is not formed as in the prior art. Get smaller. Therefore, in the embodiment in which the rotation balance adjusting unit 9 is continuously provided using the back yoke 7, not only the rotation balance adjusting unit 9 can be partially bent to adjust the rotation balance, but also the punching. The advantage of reducing the amount of waste is obtained.

  The rotation balance adjusting unit 9 may be formed in a circular shape having the same width. However, according to the rotation balance adjusting unit 9 having such a shape, only a part of the rotation balance adjusting unit 9 is partially bent to adjust the rotation balance. In some cases, the influence of the bending may extend to another part close to the bending part, and the other part may be inadvertently deformed. Sexuality will be impaired.

  Therefore, in this embodiment, the rotation balance adjusting portion 9 is partitioned into a plurality of inwardly projecting pieces 91 that can be bent by a dividing portion formed of a slit or a slit. This point will be described in detail with reference to FIG. 2, FIG. 3, or FIG.

  In the example of FIG. 2, a slit is selected as the dividing portion 10, and the slit is formed in a circular hole-like shape that has an opening at the inner peripheral edge of the rotation balance adjusting portion 9. When the dividing portion 10 is in the illustrated shape, each of the plurality of inwardly protruding pieces 91... Partitioned by the dividing portion 10 protrudes on both sides in the circumferential direction of the rotation balance adjusting portion 9. Since the narrow neck portion 93 located between the adjacent slits is provided, it is possible to easily fold the projecting portion 92 or the narrow neck portion 93 with a small force, and the folding angle. There is an advantage that the bent shape can be easily selected as desired.

  Also in the example of FIG. 3, a slit is selected as the dividing portion 10, and the slit is formed in a dovetail-like shape that has an opening at the inner peripheral edge of the rotation balance adjusting portion 9 and is open. When the dividing portion 10 is in the illustrated shape, each of the plurality of inwardly protruding pieces 91... Partitioned by the dividing portion 10 protrudes on both sides in the circumferential direction of the rotation balance adjusting portion 9. Since it has the narrow neck portion 95 located between the adjacent slits, it is possible to easily fold the protruding portion 94 or the narrow neck portion 95 with a small force. There is an advantage that the bending angle and the bending shape can be easily selected as desired.

  In the example of FIG. 4, a cut formed in the radial direction is selected as the dividing portion 10. If the dividing portion 10 is formed in the shape shown in the figure, it becomes possible to easily fold each of the plurality of inwardly projecting pieces 91... Partitioned by the dividing portion 10 with a small force. There is an advantage that it can be easily selected as desired.

  And as illustrated in FIGS. 2 to 4, a plurality of foldable inwardly projecting pieces 91 are formed at a plurality of locations in the circumferential direction of the rotation balance adjusting portion 9 by the dividing portions 10 formed of cuts or slits. In other words, when the rotation balance adjusting unit 9 is partially bent, the influence of the bending does not easily reach other portions than the bent portion, and the accuracy of the rotation balance adjustment can be easily improved. That is, when one arbitrary portion of the plurality of inwardly projecting pieces 91 is bent, the situation that the other inwardly projecting pieces 91 are deformed due to the bending does not occur, and the accuracy of the rotation balance adjustment is increased.

  In addition, the shape of the said division | segmentation part 10 is not limited to the example of illustration, If the rotation balance adjustment part 9 can be divided into the some inward protrusion piece 91 which can be bent independently, it is. Any shape is acceptable.

  In FIG. 2 to FIG. 4, symbol S indicates a space surrounded by the rotation balance adjusting unit 9, and this space S is formed by a punching trace of a sheet metal material for forming the back yoke 7. .

It is a vertical side view of the axial-flow fan which is embodiment of this invention. It is the top view of the principal part which showed the shape of the rotation balance adjustment part. It is a top view of the principal part which showed other shapes of the rotation balance adjustment part. It is the top view of the principal part which showed other shape of the rotation balance adjustment part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 4 Impeller 6 Permanent magnet 7 Back yoke 8 Rotor 9 Rotation balance adjustment part 10 Dividing part 71 Cylindrical plate part 72 Circular plate part 91 Inwardly projecting piece S Space surrounded by rotation balance adjustment part

Claims (4)

In the axial fan in which the rotor that drives the impeller includes a permanent magnet and a sheet-metal back yoke that overlaps the outer surface and the axial end surface of the permanent magnet.
The permanent magnet has a cylindrical shape, and the back yoke extends inward from one end of the cylindrical plate portion and overlaps the axial end surface of the permanent magnet, overlapping the outer surface of the permanent magnet. A rotation balance adjustment unit comprising an annular plate piece projecting inside the permanent magnet is connected to the inner periphery of the circular plate unit, and the rotation balance adjustment unit is connected to the rotation plate. The balance adjusting portion is divided into a plurality of foldable inwardly projecting pieces by a split portion formed by a slit or slit formed at a plurality of circumferential positions of the balance adjusting portion and having a starting end at an inner peripheral edge thereof. An axial fan, characterized in that an enclosed space is formed by a stamping mark of a sheet metal material for forming the back yoke. In the axial fan in which the rotor that drives the impeller includes a permanent magnet and a sheet-metal back yoke that overlaps the outer surface and the axial end surface of the permanent magnet.
A rotation balance adjusting portion that is formed of an annular plate piece projecting inside the permanent magnet and partially bendable is continuously provided on the inner peripheral portion of the overlapping portion of the back yoke with the axial end surface of the permanent magnet. An axial fan characterized by The rotation balance adjusting portion is divided into a plurality of inwardly projectable pieces that can be bent by a split portion formed by a slit or a slit formed at a plurality of locations in the circumferential direction of the rotation balance adjusting portion and having a starting end at an inner peripheral edge thereof. The axial fan according to claim 2. The permanent magnet has a cylindrical shape, and the back yoke has a cylindrical plate portion that overlaps the outer surface of the permanent magnet, and extends inwardly from one end of the cylindrical plate portion and overlaps the axial end surface of the permanent magnet. The axial flow fan according to claim 2, further comprising a circular plate portion, wherein the rotation balance adjusting portion is connected to the circular plate portion.

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