Motor-Fan Group Polymer Impeller Coupling
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Solution Overview
Problem
Existing motor-fan assemblies for heat pumps suffer from unreliable concentric positioning of the impeller with respect to the motor's rotation axis and high manufacturing costs due to the use of different materials like metal rings and polymer impellers.
Innovation Solution
A motor-fan assembly design featuring polymer impellers connected to the rotor with a concentric, reliable, and repeatable positioning achieved through a coupling mechanism using keys and key seats, eliminating the need for metal rings, and allowing both components to be made of polymer material via injection molding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If interference coupling between impeller hub wall and rotor peripheral wall is used, then the impeller can be connected to the motor, but reliable and repeatable relative positioning (concentric alignment) cannot be ensured
Solution Approach 1:
An adapter component is introduced as an intermediary element between the impeller hub wall and the rotor peripheral wall. This adapter features a first connection portion that couples to the impeller and a second connection portion that couples to the rotor, enabling precise concentric alignment through its geometric design while maintaining the interference coupling connection method.
Solution Approach 2:
The connection system is segmented into three distinct components: the impeller hub wall, the adapter, and the rotor peripheral wall. This segmentation allows each component to be optimized independently, with the adapter serving as a specialized intermediary that ensures precise concentric positioning without requiring modifications to the impeller or rotor design.
2Reliability
If a metal ring is co-molded with the impeller hub wall to strengthen it, then the stability of the interference coupling is ensured, but material and manufacturing costs increase
Solution Approach 1:
The metal ring reinforcement is extracted from the impeller design and relocated to the adapter component. This allows the impeller to be manufactured as a pure polymer part through injection molding, reducing material costs and manufacturing complexity, while the adapter (which can be made of composite or metal material) provides the necessary structural strength for stable interference coupling.
Solution Approach 2:
The strengthening function previously required in the impeller hub wall is merged with the adapter component. The adapter combines the structural reinforcement needs with the connection functionality, eliminating the need for a separate metal ring and simplifying the overall manufacturing process while maintaining coupling stability.
3Strength
If two different materials (metal ring and polymer impeller body) are used for the impeller, then the structural strength is sufficient, but manufacturing complexity and costs increase
Solution Approach 1:
The metal material is extracted from the impeller body and concentrated solely in the adapter component. This allows the impeller to be manufactured as a homogeneous polymer part, simplifying material selection, manufacturing processes, and quality control, while the adapter contains all necessary metal reinforcement for structural strength.
Solution Approach 2:
Instead of using composite materials throughout the entire impeller, the metal reinforcement is applied locally and specifically in the adapter where it is most needed for structural strength and connection stability. This localized approach maintains overall structural integrity while minimizing manufacturing complexity and material costs.
Data Source
Figure 1~2
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Figure 7~10
AI summary
A motor-fan assembly (1) for a heat pump comprises an electric motor (2) having a peripheral connection wall (5), and defining a rotation axis (6), a fan impeller (7) made of polymer material, having a hub wall (8) connected to the connection wall (5) of the motor by inserting one onto the other, a plurality of keys (10) radially protruding from one of said connection (5) and hub (8) walls, a plurality of key seats (11) formed in the other of said connection (5) and hub (8) walls to accommodate the keys (10) upon the insertion of the hub wall (8) onto the connection wall (5) in an axial insertion direction (12), one or more first stop surfaces (13) formed in one of said connection (5) and hub (8) walls and configured to abut against one or more corresponding second stop surfaces (14) formed in the other of said connection (5) and hub (8) walls, upon reaching an axial insertion end-of-stroke between the hub wall (8) and the connection wall (5), one or more first side surfaces (15) formed by each of the keys (10) and engaging corresponding second side surfaces (16) of the key seats (11), so as to achieve an anti-rotation coupling between the hub wall (8) and the connection wall (5) about the rotation axis (6).