JP3576309B2 - Fan motor impeller structure - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an impeller structure of a fan motor having an impeller having a shaft fixed to a central boss portion and a blade portion on an outer periphery.
[0002]
[Prior art]
FIG. 8 shows the structure of a conventional fan motor generally used. For example, the housing 11 is formed in a square frame shape, and the bottom plate 12 is integrally formed below the housing 11. At the center of the bottom plate 12, a bearing tower 14 into which a bearing 13 is fitted is erected with its lower end fixed. A circuit board 15 is mounted above the bottom plate 12, and electronic components such as a Hall IC 16 and a drive IC 17 are mounted on the circuit board 15. On the outer peripheral side of the bearing tower 14, a stator 21 in which insulators 19 a and 19 b are covered above and below the stator core 18 and a coil 20 is wound is fixed.
[0003]
On the other hand, the impeller 7a has a bowl-shaped rotor 6a, a yoke 9 fitted inside and holding a rotor magnet 8, and vanes 10 radially arranged on the outer periphery of the rotor 6a. A thick cylindrical boss 2a is formed at the center of the rotor 6a, and the shaft 5 is fitted and fixed to the center of the boss 2a. Specifically, insert molding is performed. The shaft 5 is pivotally supported inside the bearing tower 14 via the bearing 13. The shaft 5 is held in the bearing tower 14 via the bearing 13 by the retaining washer 22 as shown in the figure.
[0004]
[Problems to be solved by the invention]
FIG. 9 is a perspective view showing the structure around the boss 2a of the impeller 7a in FIG. As shown, the boss portion 2a is much thicker than the portion of the rotor 6a around it. This is to secure and improve the removal strength (fixed strength) of the shaft 5 fitted to the boss portion 2a and to secure the orthogonality of the rotor 6a to the shaft 5. The boss 2a has an integral structure with the rotor 6a and is formed of resin. However, there is a difference in thickness between the boss 2a and the rotor 6a around the boss 2a. Conditions are slightly different. For this reason, the heat contraction speed of the boss portion 2a after molding and the rotor 6a around it differs, or the heat contraction speed of the boss portion 2a itself slightly changes. Therefore, a non-uniform force, that is, a pulling force acts on the boss portion 2a in the outer peripheral direction. As a result, the shaft 5 fixed to the boss portion 2a at the time of molding is tilted, tilted, or rattled, thereby deteriorating the orthogonality between the shaft 5 and the rotor 6a, causing noise during driving, and causing impeller impeller. There is a problem in that the rotor magnet 8a and the stator 21 come into contact with each other and the motor characteristics deteriorate.
[0005]
The present invention has been made to solve the above problems, and an object of the present invention is to provide a fan motor impeller structure that can secure the fixed strength of a shaft and the orthogonality between a shaft and a rotor side, and that is simple and inexpensive. I do.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a housing with a bottom plate, a bearing tower that is erected with its lower end fixed to the center of the bottom plate, a stator held on the bearing tower side, The impeller structure in a fan motor having a rotor magnet opposed to a stator inside, having a blade portion on an outer peripheral side, and an impeller fixed to a shaft supported on the bearing tower side at a central boss portion. a is, the boss portion of the impeller is formed in a cylindrical shape, a plurality of slits are formed radially on its outer periphery, the outer diameter of the boss portion, the end portion opposite to the boss portion of the bearing tower are either slightly larger equal to the outer diameter, during the movement of the axial direction of the impeller, the bearing data before the central portion of the boss portion abuts on the bearing It is characterized in that the end portion of the over abuts on the boss portion. A plurality of tongue-shaped impeller receivers are protruded from the end of the bearing tower, and the width of each impeller receiver in the rotational direction is larger than the width of the slit in the rotational direction.
[0007]
By providing a slit in the outer peripheral portion of the boss portion, the slit absorbs uneven shrinkage caused by thermal shrinkage around the boss portion after molding, and prevents the shaft from falling down . Shi Yafuto is to be fixedly held strongly with no boss slits, fixing strength such as dropout or collapse is ensured. Slits are easily without requiring post-processing special intended to be simultaneously formed during molding, and low cost implementation. By forming a plurality radially slits equally spaced around the boss portion of the cylindrical, uniform heat shrinkage of the boss portion is secured. Also, since the outer diameter of the boss is formed to be equal to or slightly larger than the outer diameter of the tip of the bearing tower, when the impeller is moved in the axial direction, the tip of the bearing tower is moved before the boss contacts the bearing. Abuts against the boss so that no direct stress is applied to the bearing.
Further, since the tongue-shaped impeller receiver at the tip of the bearing tower abuts the boss, the impact at the time of collision between the bearing tower and the impeller becomes extremely small. The width of each impeller receiver in the rotation direction is formed larger than the width of the slit of the boss in the rotation direction, so that a safe contact can be realized regardless of the rotation position of the impeller.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of an impeller structure of a fan motor of the present invention will be described in detail with reference to the drawings. FIG. 1 shows the overall structure of a fan motor using an impeller according to the present invention.
A rectangular frame-shaped housing 31 made of a resin molded product has a bottom plate 33 integrally formed with a leg 32 at the center of the bottom of the housing 31, and a cylindrical bearing tower 34 protrudes from the center of the bottom plate 33. I have. The bottom plate 33 and the bearing tower 34 are integrally formed when the housing 31 is molded with resin. A stator 36 holding a circuit board 35 is fitted on the outer peripheral surface of the bearing tower 34. The stator 36 is configured by covering insulators 38a and 38b above and below a stator core 37 and winding a coil 39. An end of the coil 39 is connected to a pin 40 projecting from the lower insulator 38b. The pins 40 are soldered to the circuit board 35 and fitted to the bearing tower 34 with the stator 36 holding the circuit board 35, so that the circuit board 35 is positioned at the bottom plate 33. Placed in Electronic components such as a Hall IC and a drive IC are mounted on the circuit board 35.
[0009]
The impeller 41 of the present fan motor includes a cup-shaped rotor holder 43 having a boss 42 formed in the center, vanes 44 arranged at equal intervals along the radial direction on the outer periphery thereof, and a cylindrical yoke inside the rotor holder 43. A shaft 47 is fixed to the boss portion 42 by insert molding or the like. 2 to 4 show the detailed structure of the boss portion 42. The boss portion 42 includes a cylindrical portion 42a for fixing the shaft 47 inside, a spring receiving seat 42b formed one step lower outside the cylindrical portion 42a, and a contact receiving seat 42c formed one step lower outside the receiving seat 42b. And a plurality of slits 48 are formed radially and at equal intervals at the positions of both receiving seats 42b and 42c. The boss portion 42 having the slit 48 is integrally formed during resin molding of the rotor holder 43 and the blade portion 44, and the shaft 47 is simultaneously insert-molded. The cylindrical portion 42a is formed to have a thickness and a dimension that can secure the fixing strength of the shaft 47, and the receiving seats 42b and 42c are formed to have a thickness that can sufficiently reinforce the cylindrical portion 42a. Although the number of slits 48 is different between FIG. 2 and FIG. 4, it is shown that an appropriate number is used according to the size of the impeller 41 and the shape of the shaft 47.
[0010]
By adopting the above structure, the difference in heat shrinkage during resin molding between the boss portion 42 and the rotor holder 43 around the boss portion 42 is absorbed by the slit 48 in the boss portion 42, and the difference in heat shrinkage is smaller than that of the prior art. Is reduced, and the shaft 47 is prevented from falling down. Further, the fixing strength of the shaft 47 is ensured by the two receiving seats 42b and 42c even when the cylindrical portion 42a is thin. Therefore, the orthogonality between the shaft 47 and the rotor holder 43 is ensured.
[0011]
The impeller 41 described above is rotatably supported by supporting the shaft 47 inside the bearing tower 34 via bearings 49 and 50. That is, bearings 49 and 50 are inserted into the inside of the bearing tower 34 from above and below, and are positioned by the internal stepped portion 51, and the shaft 47 is sequentially passed through the inside of the upper and lower bearings 49 and 50 to the tip of the shaft 47. By mounting the stopper 52, the impeller 41 is supported via the shaft 47. At this time, a compression coil spring 53 is interposed between the inner ring end face of the upper bearing 49 and the spring receiving seat 42b of the boss portion 42, and realizes preloading of the bearings 49 and 50 and holding of the position of the impeller 41. . The impeller 41 is normally held in a state in which the stopper 52 comes into contact with the inner ring end face of the lower bearing 50 by this spring force, but can be displaced in the axial direction.
[0012]
Here, the outer diameter of the boss portion 42 is formed to be equal to or slightly larger than the outer diameter of the tip portion of the bearing tower 34. For this reason, when the impeller 41 moves in the axial direction, before the cylindrical portion 42 a of the boss portion 42 contacts the bearing 49, the distal end portion of the bearing tower 34 contacts the contact receiving seat 42 c of the boss portion 42 and directly contacts the bearing 49. Stress is not applied. As shown in FIG. 5, four tongue-shaped impeller receivers 54 protrude from the tip of the bearing tower 34, and each impeller receiver 54 comes into contact with the boss 42. Since the tongue-shaped impeller receiver 54 comes into contact with the boss portion 42, the impact at the time of collision between the bearing tower 34 and the impeller 41 is extremely small. The rotational width of each impeller receiver 54 is formed to be larger than the rotational width of the slit 48 of the boss portion 42, so that a safe hit can be realized regardless of the rotational position of the impeller 41.
[0013]
Incidentally, the rotor magnet 46 of the impeller 41 described above is magnetized using a magnetizing device 55 as shown in FIG. That is, in order to magnetize the rotor magnet 46, in the prior art, a dedicated magnetizing jig corresponding to the diameter of the rotor magnet was used. Rotor magnets used for fan motors and the like have various shapes depending on the capacity of the fan motor, and have different diameters. Therefore, it is necessary to prepare a dedicated jig for each rotor magnet, which increases the jig cost and also makes maintenance and storage management of the jig complicated. The magnetizing device 55 of the present example has solved the above-mentioned conventional problems.
[0014]
The magnetizing device 55 includes a yoke 57 in which a plurality of (four in the illustrated) legs 56 are arranged on the inner surface thereof in a radial direction, a coil 58 wound around the legs 56, and a magnet holder 59. Become. As shown in FIG. 6, in this example, the four legs 56 extend in the radial direction by the same length, and the tips form flat surfaces. Therefore, the space surrounded by the flat surface forms a rectangular outline. The magnet holder 59 has a square outer contour fitted in the contour, and has an inner hole 60 for holding the rotor magnet 46 therein, a holder body 61 surrounding the inner hole 60, and a leg portion 56 facing each other. An auxiliary yoke 62 is provided and held by the holder body 61. Note that the magnet holder 59 is made of an insulating material, and is formed of, for example, Araldite. The outer contour of the magnet holder 59 is of a certain size that fits within the above-mentioned square contour surrounded by the leg portion 56, and its inner hole 60 has various dimensions corresponding to the outer diameter of the rotor magnet 46. Is prepared. That is, in the magnetizing device 55 of this example, the yoke 57 is common, and only a plurality of types of magnet holders 59 that are inserted into the contour of the yoke 57 are prepared corresponding to the dimensions of the rotor magnet 46.
[0015]
Next, a method of magnetizing the rotor magnet 46 by the magnetizing device 55 will be described. First, a magnet holder 59 corresponding to the outer diameter of the rotor magnet 46 to be magnetized is prepared, and the rotor magnet 46 is inserted into the inner hole 60 thereof. The magnet holder 59 with the rotor magnet 46 inserted therein is inserted into the contour surrounded by the flat surface at the tip of the leg 56 of the yoke 57. Thereby, the leg 56 and the auxiliary yoke 62 come into contact with each other. When a high voltage and a large current are supplied to the coil 58 wound around the leg 56, the magnetic flux generated by the energization of the coil 58 passes through the rotor magnet 46 using each leg 56 and the auxiliary yoke 62 as a magnetic path, and 46 is magnetized in the radial direction. As described above, the magnet holder 59 corresponding to the rotor magnets 46 having different outer diameters is used.
[0016]
FIG. 7 shows another example of the magnet holder. As shown, the magnet holders 59a and 59b form the same outer contour as the magnet holder 59 of FIG. 6, but FIG. 7A shows that the auxiliary yoke 29a has a straight shape, The holder main body 61a also has a straight shape. When the outer diameter of the rotor magnet 46 is large, the auxiliary yoke 62 needs to be tapered as shown in FIG. 6 to prevent the contact area between the auxiliary yoke 62 and the rotor magnet 46 from decreasing. When the outer diameter of the rotor yoke is small, the contact area between the auxiliary yoke 62a and the rotor magnet 46 can be maintained with the straight type shown in FIG. That is, the magnet holder 59a of FIG. 7A is applied to the rotor magnet 46 having a small outer diameter, and the magnet holder of FIG. 6 is applied to the rotor magnet 46 having a relatively large diameter.
[0017]
The magnet yoke 59b in FIG. 7B has an auxiliary yoke 62b formed to be inclined with respect to the axial direction of the holder main body 61b. Of course, the holder main body 61b is also inclined according to the inclination angle of the auxiliary yoke 62b. By tilting the auxiliary yoke 62b, so-called skew magnetization can be performed. Note that this inclination angle is appropriately set.
[0018]
By using the magnetizing device 55 having the above-described structure, it is possible to magnetize various types of the rotor magnets 46 with a common jig, thereby reducing equipment costs and facilitating maintenance and storage management. Also, skew magnetization is possible.
[0019]
【The invention's effect】
1) According to the impeller structure of the fan motor according to the first aspect of the present invention, since the slit is formed in the outer peripheral portion of the thick boss portion of the impeller, the heat shrinkage between the boss portion and the periphery thereof during molding is uniform. Therefore, the shaft fitted to the boss portion does not fall or tilt, and the orthogonality between the shaft and the rotor is ensured. Also, the shaping of the slit hardly reduces the fixing strength of the shaft. Further, the outer diameter of the boss portion is formed to be equal to or slightly larger than the outer diameter of the end portion of the bearing tower, and when the impeller moves in the axial direction, the end portion of the bearing tower before the center portion of the boss contacts the bearing. Is made to contact the boss portion, so that even if an impact or the like is applied to the impeller, no direct stress is applied to the bearing, and a long-life impeller structure can be provided.
2) According to the impeller structure of the fan motor according to the second aspect of the present invention, the tongue-shaped impeller receiver at the tip of the bearing tower comes into contact with the boss portion, so that a collision between the bearing tower and the impeller can occur. The impact is very small. The width of each impeller receiver in the rotation direction is larger than the width of the slit in the boss, so that it can achieve a safe contact regardless of the rotation position of the impeller and provide a long-life impeller structure. It is.
[Brief description of the drawings]
FIG. 1 is an overall cut-away front view of a fan motor showing an embodiment of an impeller structure of the fan motor of the present invention.
FIG. 2 is a bottom view of the impeller of FIG. 1;
FIG. 3 is a front view cut along line AA of FIG. 2;
FIG. 4 is a perspective view showing a boss of the impeller of FIG. 1;
FIG. 5 is a perspective view of the bearing tower of FIG. 1;
FIG. 6 is a plan view of a magnetizing device for magnetizing a rotor magnet.
FIG. 7 is a plan view showing another example of the magnet holder applied to the magnetizing device of FIG. 6;
FIG. 8 is a cut-away front view showing the entire structure of a conventional fan motor.
FIG. 9 is a perspective view showing a structure around a boss portion of an impeller of a conventional fan motor.
[Explanation of symbols]
31 Housing 33 Bottom plate 34 Bearing tower 36 Stator 41 Impeller 42 Boss part 42a Cylindrical part 42b Spring receiving seat 42c Hit seat 46 Rotor magnet 47 Shaft 48 Slit 54 Impeller receiving

Claims (2)

A housing with a bottom plate, a bearing tower erected with the lower end fixed to the center of the bottom plate, a stator held on the bearing tower side, and a rotor magnet opposed to the stator provided inside the outer periphery The impeller structure in a fan motor provided with an impeller having a blade portion and a shaft that is pivotally supported on the bearing tower side provided at a center boss portion, wherein the boss portion of the impeller is cylindrical. The outer diameter of the boss portion is formed equal to or slightly larger than the outer diameter of the end of the bearing tower facing the boss portion, when the axial movement of the impeller, this end portion of the bearing tower before the central portion of the boss portion is in contact with the said bearing is brought into contact with the boss portion Impeller structure of a fan motor according to claim. 2. The bearing according to claim 1, wherein a plurality of tongue-shaped impeller receivers protrude from an end portion of the bearing tower, and a width of each impeller receiver in the rotation direction is larger than a width of the slit in the rotation direction. 3 . Fan motor impeller structure.

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