JPH11223196A - Rotor of axial fan - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify the management of the parts and to improve the reliability on the binding strength with a rotor shaft with the restriction on length in the axial direction by forming a rotor holding member with a material which is a magnetic member and superior in the mechanical strength, such as an iron-sintered member or the like, and integrating the same with a back york. SOLUTION: A holding member 5-4 forming a rotor is a magnetic member, and integrated with a back york 5-2. The short stroke is required in the connection holding part of the holding member 5-4 and the rotor shft 4 in consideration of the necessity of the flatness and the restriction on length in the axial direction. The holding member 5-4 is formed by, for example, an iron-sintered bdy, and integrated with the back york 5-2 to ensure the binding strength with the rotor shaft 4, and the reliability on the screwing strength is kept by binding the holding member 5-4 and an arm holding member 3 integrated with a blade by a screw member 9. Further, a low cylindrical part 5-5 as a contact face with a barrel of a rotatably pivotted bearing, is integrally formed on a peripheral edge of the engagement hole with the rotor shaft 4 of a cup-shaped holding member 5-4 acting also as the back york.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an axial fan, and more particularly, to an improved rotor for an axial fan using a brushless DC motor.

[0002]

2. Description of the Related Art FIG. 4 shows a conventional brushless D.
In the cross-sectional view of the C fan, the rotating part that is integral with the impeller 1 is:
A bowl-shaped holder 3 having a blade 2 provided on the outer peripheral surface of the cylindrical portion, and a rotor 5 of a driving motor having a rotor shaft 4 connected and held at the center of the bottom surface of the bowl-shaped holder 3. ,
These are rotatably supported by bearings 8 mounted on a bearing box of a motor holding unit 7 which is integral with the venturi case 6.

The rotor 5 of the driving motor has a cylindrical permanent magnet 5-3 provided on a cylindrical outer peripheral surface thereof via a back yoke 5-2 together with a cup-shaped holding member 5-1. Since the shape holding member 5-1 is made of a non-magnetic material, a back yoke 5-2 is additionally provided to effectively utilize the performance of the permanent magnet. Although the cup-shaped holding member 5-1 may be formed by resin molding, an aluminum die-cast structure is often used to maintain the coupling strength with the rotor shaft 4 due to restrictions on the axial length. Was.

[0004]

In the conventional construction as described above, the cup-shaped holding member, which is a structural member, and the back yoke used together due to magnetic requirements are formed separately and joined to each other to form a rotor. Therefore, in addition to demerits in parts management, there has been a demand for a solution in terms of maintaining the fitting accuracy of both sides that are always attached to the combined structure.

[0005]

The rotor of the axial fan according to the present invention comprises a cylindrical permanent magnet and a cup-shaped back yoke made of an iron-based sintered member. A fixing screw screw hole with the housing is provided near the outer peripheral edge of the bottom surface, and a fitting hole with the rotor shaft is provided at the center thereof, and the disc-shaped bottom inner surface of the cup-shaped back yoke is provided. A small cylindrical protrusion for abutting the bearing end surface is formed around the hole for fitting with the rotor shaft, and at least one axially extending concave groove is formed on the inner peripheral surface of the cylindrical permanent magnet. Are formed, and a convex portion corresponding to the concave groove is provided on the outer peripheral surface of the cylindrical portion of the cup-shaped back yoke, and the permanent magnet is positioned and held by fitting the two.

As described above, the rotor holding member is formed of a magnetic material and a material advantageous in terms of mechanical strength, such as an iron-based sintered member disclosed in the present application, so that the rotor holding member can be integrated with the back yoke. It is also possible to improve the reliability of the coupling strength with the rotor shaft within the restriction on the axial length.

[0007]

FIG. 1 is a cross-sectional view of an example of an axial fan according to the present invention. As is clear from comparison with the conventional structure shown in FIG. 4, the overall structure of the axial fan is similar. However, as shown in FIG. 2, only the main part of the rotor is shown in cross section, the holding member 5-4 forming the rotor is a magnetic member and is integrated with the back yoke 5-2.

Since the flatness is required and the length in the axial direction is severely restricted, the holding member 5-1 and the rotor shaft 4 are required.
A short stroke is required for the connection holding portion with the blade 2. For example, according to a means such as iron-based sintering, the connection strength with the rotor shaft 4 is ensured, and the The use of the screw member 9 as a means for coupling to the holder 3 is also effective in maintaining the reliability of the screwing strength.

The cup-shaped holding member 5-4 also serving as the back yoke has a low cylindrical portion 5-5 as a contact surface of a bearing 6 rotatably supported on the periphery of a fitting hole with the rotor shaft 4. Can be formed integrally.

As shown in FIG. 3 which is a front view of FIG. 2, a concave groove extending in the axial direction preferably corresponding to the number of magnetic poles of the permanent magnet 5-3 is formed on the inner peripheral surface of the cylindrical permanent magnet 5-3. (Three in the figure) 5-6 are provided, and on the outer peripheral surface of the cylindrical portion 5-2 of the cup-shaped holding member 5-4, an axial convex portion 5-7 corresponding to the concave groove is formed, and It is also effective to maintain the strength in the turning direction by fitting.

[0011]

According to the rotor of the axial flow fan according to the present invention, the cup-shaped holding member, which is a structural member, and the back yoke used together because of magnetic requirements are integrated, so that parts management can be simplified, and The combination structure brings about an operation and effect that does not require consideration for maintaining the fitting accuracy of the two members always attached.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an example of an axial fan according to the present invention.

FIG. 2 is an enlarged sectional view of a main part of the rotor of the example of FIG.

FIG. 3 is a front view of the example of FIG. 2;

FIG. 4 is a cross-sectional view showing an example of an axial fan according to the related art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Impeller 2 Blade 3 Bowl-shaped holder 4 Rotating shaft 5 Rotor 5-1 Cup-shaped holding member 5-2 Back yoke 5.3 Permanent magnet 5.4 Cup-shaped holding member 5-5 Small cylindrical protrusion 5-6 Groove on inner peripheral surface of permanent magnet 5-7 Projection of cup-shaped yoke 6 Venturi case 7 Motor holder 8 Bearing 9 Screw member

Claims (2)

[Claims] 1. A venturi case having a cylindrical wind tunnel portion, and an impeller rotatably supported by a plurality of blades on an outer peripheral surface of a cylindrical hub so as to face an inner peripheral surface of the wind tunnel portion via a small gap. And an electric motor disposed on the inner peripheral surface of the cylindrical hub for driving the impeller, wherein the rotor comprises a cylindrical permanent magnet and a cup comprising an iron-based sintered member. A back screw is provided near the outer peripheral edge of the disk-shaped bottom surface of the cup-shaped back yoke. A fitting hole is provided,
An axial flow, wherein a small cylindrical projection for contacting a bearing end face is formed around a fitting hole with the rotor shaft on the inner surface of the disk-shaped bottom of the cup-shaped back yoke. Fan rotor. 2. An inner peripheral surface of the cylindrical permanent magnet is formed with at least one axially extending concave groove, and a convex corresponding to the concave groove is formed on an outer peripheral surface of a cylindrical portion of the cup-shaped back yoke. The rotor of the axial flow fan according to claim 1, wherein a part is provided, and the permanent magnet is positioned and held by fitting the two parts.