Fan assembly

Abstract

A fan assembly includes an impeller portion generating an air flow and a motor that rotates the impeller portion about a center axis. The impeller portion is attached to a yoke of a rotor portion of the motor and is rotated with the yoke. A circular portion of the impeller is attached to a bottom opening of the yoke having a cylindrical shape whose top is covered by insert molding. Therefore, the impeller and the yoke may be securely fixed to each other. In addition, an outer side surface of the yoke is exposed to outside air such that the space arranged inward from the plurality of blades may be enlarged.

Description

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention generally relates to an electrically powered fan assembly used to blow air. [0003] 2. Description of the Related Art [0004] Conventionally, a centrifugal type fan assembly, taking air in an axial direction and exhausting the air in a radial direction, has the following configuration. Specifically, the conventional fan assembly includes an impeller having a plurality of blades arranged in a circumferential direction centered about a center axis, and a substantially cup-shaped portion arranged at the middle of the impeller into which a substantially cylindrical yoke made of magnetic material is press-fitted. In addition, a field magnet is attached to an inner side surface of the yoke. By virtue of this configuration, the impeller is rotatably supported around the center axis. The blades of the impeller are arranged on radially outer positions of the cup-shaped portion, and the cup-shaped portion ...

AI Technical Summary

Benefits of technology

The present invention provides a fan assembly with an improved blower efficiency and prevention of damage or cracks caused by thermal deformation. This is achieved by securely fixing the impeller portion to the yoke using insert molding, with the outer side surface of the yoke exposed. Additionally, a flange portion may be included to further reinforce the attachment of the impeller portion. The invention also includes the use of weld lines and gate marks to prevent damages or cracks of the impeller portion. Overall, the invention provides a more robust and reliable fan assembly.

Problems solved by technology

As a result, the motor efficiency is degraded.

Upon making a diameter of the circular space bigger while fixing an outer diameter of the impeller, a blade-area will be decreased in size, which results in degraded blower efficiency.

However, in case that the permanent-magnet rotor and the cylindrical portion arranged at the middle portion of the impeller are press-fitted or bonded, an axial length of an affixing area at which the outer side surface of the permanent-magnet rotor is abutted against the impeller is short.

Therefore, the impeller may not be fixed securely to the permanent-magnet rotor by press-fitting or bonding.

For crimp-fixing, forming the engaging portion and crimping processes are required, which may deteriorate the work efficiency.

Furthermore, the cup shaped portion of the impeller, which is made of resin, may be broken or cracked by the stress generated upon press-fitting the permanent magnet rotator (i.e., the cylindrical yoke made of metallic material with the field magnet attached to the inner side surface thereof) into the cup-shaped portion.

Especially in a large-size fan, it is highly probable that the impeller is damaged or cracked.

On the other hand, if the press-fit pressure is reduced, the permanent-magnet rotor may not be securely fixed to the impeller.

In case that such a fan assembly is utilized in a low temperature environment, the impeller made of resin shrinks more than the yoke made of metallic material does, which results in breaking or cracking of the attaching portion of the impeller and the yoke.

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