Rotational Position Sensor Fixing Member Press Forming
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Solution Overview
Problem
The existing rotational position sensing apparatuses for electric motors face increased manufacturing costs due to complex and time-consuming processes required for forming projections on the fixing member, such as press working, machining, or hydroforming, which are necessary to securely hold the rotational position sensing magnet.
Innovation Solution
A rotational position sensing apparatus with a fixing member made of non-magnetic metal, featuring a tubular first peripheral wall portion, an annular bottom wall portion, and radially inwardly projecting projections arranged circumferentially, which are formed through a press working process without separating components, allowing for low-cost manufacturing by eliminating the need for advanced forming technologies and reducing processing time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the projection is formed by press working process along the inner peripheral surface all around, then the rotational position sensing magnet can be securely held, but the peripheral wall portion needs to be separately formed from the bottom wall portion increasing manufacturing steps and costs
Solution Approach 1:
The press working process is segmented into multiple stages: first forming a preliminary projection that extends axially, then forming a secondary projection that extends radially inwardly. This segmentation allows the projection to be formed in steps without requiring separate component formation, resolving the contradiction between secure holding and manufacturing complexity.
Solution Approach 2:
The preliminary projection is formed first as a preparatory action before the final radial projection is created. This preliminary structure provides a foundation for the subsequent radial projection formation, enabling secure magnet holding while maintaining manufacturing simplicity through integrated forming.
2Reliability
If the projection is formed by machining process, then the rotational position sensing magnet can be held, but the processing time is relatively long increasing manufacturing costs
Solution Approach 1:
The machining process (mechanical removal of material) is replaced with a press working process (mechanical forming). This substitution eliminates time-consuming material removal operations while achieving the same functional result of creating projections that securely hold the rotational position sensing magnet, thereby improving productivity without sacrificing reliability.
3Reliability
If the projection is formed by hydroforming process, then the rotational position sensing magnet can be held, but advanced forming technology is required increasing manufacturing costs
Solution Approach 1:
The patent employs a simple press working die structure that can be easily manufactured and replaced if needed, rather than requiring complex hydroforming equipment. This approach uses readily available, cost-effective forming technology to create the necessary projections, improving ease of manufacture while maintaining the reliability of magnet holding.
4Ease of manufacture
If the peripheral wall portion is separately formed from the bottom wall portion, then the press working process can be performed, but the number of manufacturing steps is increased
Solution Approach 1:
The peripheral wall portion and bottom wall portion are merged into a single integrated component that is formed in one press working operation. The projection is formed directly on the integrated structure, eliminating the need for separate component formation and assembly steps, thereby improving manufacturing efficiency while maintaining press working feasibility.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables the cost-effective production of the fixing member by simplifying the manufacturing process, reducing stress concentration on the rotational position sensing magnet, and enhancing the structural integrity of the fixing member, thereby improving the overall efficiency and reliability of the rotational position sensing apparatus.
Implementation Method 1
a rotational position sensing magnet 130 that generates a magnetic flux, which is used for sensing a rotational position of a rotor 12 with the magnetic sensor 132
Implementation Method 2
The projections 131c-131j are formed in the inner peripheral surface of the first peripheral wall portion 131a through a press working process
Data Source
AI summary
A rotational position sensing apparatus includes a rotational position sensing magnet and a fixing member. The fixing member is made of a non-magnetic material and is fixed to a rotatable shaft of a rotor. The fixing member includes a plurality of projections, which radially inwardly project and are arranged one after another in a circumferential direction at an inner peripheral surface of a first peripheral wall portion within a space, which is defined by the first peripheral wall portion and a bottom wall portion and holds the rotational position sensing magnet.