Centrifugal Fan Impeller Back Yoke Fitting Connection
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Solution Overview
Problem
Conventional centrifugal blowing fans face challenges in connecting impellers and back yokes under severe environments due to thermal shrinkage differences between metal and resin components, leading to increased costs and complexity in manufacturing, especially when requiring precise alignment and heat-sensitive connections.
Innovation Solution
A centrifugal blowing fan design featuring a metal back yoke with a flange portion and a resin impeller with protrusions or claws, where the impeller is concentrically fixed to the back yoke using fittings and fitted spaces, allowing for easy alignment and secure connection without the need for extensive resin coverage, thus preventing thermal damage and reducing manufacturing time and costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a ring portion made from resin is insert-molded into the opening or outer surface of a back yoke made from metal, and the impeller is ultrasonic-welded to the ring portion, then the impeller and back yoke are fixedly connected, but the manufacturing process requires a lot of man-hours and increases costs
Solution Approach 1:
The invention merges the connection function into a single integral structure by providing fitting portions directly on the impeller that engage with fitted spaces in the back yoke. This eliminates the need for separate ring portions and ultrasonic-welding operations, reducing manufacturing steps while maintaining reliable connection between the impeller and back yoke.
2Reliability
If the impeller and back yoke are connected by covering the outer circumference of the back yoke with an accommodation made from resin, then the connection is achieved, but the accommodation is damaged due to the difference of thermal shrinkage between the accommodation made from resin and the back yoke made from metal
Solution Approach 1:
The invention extracts the problematic accommodation structure that is susceptible to thermal shrinkage damage. Instead of using a resin accommodation that covers the back yoke outer circumference, the design uses direct fitting portions on the impeller that engage with fitted spaces in the metal back yoke, eliminating the thermal incompatibility issue while maintaining connection stability.
3Reliability
If the ring portion is connected with the back yoke at a location near the opening and/or outer surface of the back yoke, then the connection is achieved, but this location is near a source of heat and would be subject to influence by heat
Solution Approach 1:
The invention changes the spatial dimension of the connection location. Instead of connecting at the outer surface or opening area of the back yoke where heat influence is strong, the fitting portions are provided on the inner circumferential surface of the impeller, moving the connection interface to a location away from heat sources while maintaining connection strength.
4Reliability
If the back yoke and impeller are integrally formed from one steel plate, then the connection is achieved, but it is difficult to realize such structure in case of an impeller with a certain height or an impeller having a lot of blades
Solution Approach 1:
The invention segments the impeller and back yoke into separate components that can be independently manufactured and then assembled through the fitting portions and fitted spaces. This allows the impeller to be designed with various heights and blade configurations without being constrained by integral formation requirements, while still achieving reliable connection and structural integrity.
Data Source
AI summary
A centrifugal blowing fan comprises a back yoke made from metal, having a substantially bottomed cylindrical portion around a rotating shaft of a motor, an inner surface attached with a magnet of the motor mounted thereon and a flange portion disposed around a periphery of an opening of the cylindrical portion; and a cylindrical impeller made from resin, having a plurality of blades circumferentially arranged, an annular collar portion joined with first ends of the plurality of blades and a doughnut-shaped disk portion joined with second ends of the plurality of blades, wherein the disk portion has at least one fitting, and the flange portion has at least one fitted space receiving the at least one fitting so as to concentrically and fixedly connect the impeller 16 and the back yoke.