Rotor Position Sensor Fixing Arm Overmolding
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Solution Overview
Problem
Conventional position measuring devices for rotating electric machines face issues with calibration desynchronization due to material expansion differences during thermal shocks and vibrations, and they require complex manufacturing processes with multiple parts, leading to increased costs and assembly time.
Innovation Solution
A simplified position measuring device with a metal-to-metal fixing mechanism, where the fixing means are integrated into the fixing arm through overmolding, reducing the number of parts and ensuring no play during thermal shocks, and allowing for easier calibration and assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the mounting arm, bearing and retaining plate are made of different materials (plastic and metal) to enable assembly, then the position measuring device can be manufactured and assembled, but the different coefficients of expansion cause play between parts during thermal shocks, leading to desynchronization between position sensors and target
Solution Approach 1:
The patent applies homogeneity by making both the mounting arm and the bearing from the same plastic material. This eliminates the interface between different materials (metal and plastic) that caused thermal expansion mismatches. The retaining plate is also made of plastic, creating a homogeneous plastic assembly that expands uniformly during thermal shocks, preventing play and desynchronization while maintaining ease of manufacture through injection molding.
Solution Approach 2:
The patent uses composite materials by creating an integrated plastic component that combines the mounting arm, bearing, and retaining plate functions into a single molded part. This composite plastic structure eliminates the need for metal-bearing interfaces, resolving the thermal expansion conflict while maintaining structural integrity and assembly simplicity through a single-material construction.
2Reliability
If several parts (mounting arm, bearing, retaining plate, screws) are used to secure the position measuring device, then the device can be firmly attached to the bearing, but the number of parts increases, complicating manufacturing and assembly processes
Solution Approach 1:
The patent merges the mounting arm, bearing, and retaining plate into a single integrated plastic component manufactured through injection molding. This consolidation reduces the part count from multiple separate components (mounting arm, bearing, retaining plate, screws) to one unified piece, simplifying manufacturing and assembly while maintaining secure attachment through the integrated design that incorporates all fastening functions within the molded structure.
3Reliability
If multiple parts and assembly steps are required to secure the position measuring device, then proper fixation can be achieved, but manufacturing time and costs increase
Solution Approach 1:
The patent combines multiple manufacturing steps and parts into a single injection molding process that produces the integrated mounting arm-bearing-retaining plate assembly in one operation. This eliminates sequential assembly steps, reduces manufacturing time, and lowers costs while maintaining fixation stability through the designed integrated structure that incorporates all necessary fastening features.
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 provides a stable and calibrated position measuring device with reduced manufacturing complexity and costs, preventing desynchronization and simplifying the assembly process by using a single molding step and fewer parts, ensuring reliable operation under varying conditions.
Implementation Method 1
the fixing means are overmolded in the fixing arm during an overmolding operation so as to obtain fixing means integrated in the fixing arm
Implementation Method 2
Conventionally, the position sensor is a Hall effect sensor detecting magnets that are part of the target
Data Source
Figure 1~2
Figure 3
AI summary
The present invention relates to a position measuring device (1) for a stator unit (2) of a rotary electric machine (3), comprising fixing means (8) that are connected to fixing arms (7) and that are intended to be fixed to a bearing (9) of the stator unit (2), the bearing (9) being positioned at an axial end (10) of the stator unit (2).