Deformable Pin Fixes Angular Sensor Rotor on Motor Shaft
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Angular position sensor errors in electric motor assemblies due to clearances between the sensor rotor and the motor shaft, exacerbated in multi-pole motors, lead to inaccurate motor position data, affecting the control of electric traction motors in vehicles.
Innovation Solution
An electric motor assembly design that includes a motor shaft with an axial keyway and an angular position sensor rotor with an axial key, where a deformable pin is inserted into the clearance space between the key and the keyway to inhibit rotational shifting, ensuring precise alignment and reducing sensor data errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a deformable pin is inserted into the clearance space between the axial key and keyway to inhibit rotational shifting, then measurement precision and reliability are improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
A deformable pin is introduced as an intermediary element between the axial key and keyway. The pin fills the clearance space and, when deformed, creates frictional engagement that prevents rotational shifting of the sensor rotor relative to the motor shaft, thereby improving measurement precision without requiring a complete redesign of the key-keyway connection
Solution Approach 2:
The deformable pin changes its physical state from a flexible configuration during insertion to a rigid, deformed configuration during operation. This parameter change allows the pin to transition from an easy-to-install state to a high-friction engagement state that effectively eliminates rotational play between the key and keyway
2Ease of manufacture
If fabrication tolerances and manufacturing variations are accepted to simplify production, then ease of manufacture is improved, but sensor rotor stability and measurement precision deteriorate
Solution Approach 1:
The deformable pin serves as a compensating intermediary that absorbs the effects of fabrication tolerances. By deforming to fill the clearance space, the pin accommodates manufacturing variations in the key and keyway dimensions while still providing sufficient frictional force to prevent rotational shifting, thus maintaining stability despite relaxed tolerance requirements
3Measurement precision
If the axial key dimension is reduced to match the keyway dimension exactly to eliminate clearance, then measurement precision is improved, but ease of manufacture and assembly difficulty worsen
Solution Approach 1:
Rather than requiring the axial key to fit the keyway with zero clearance (which would demand extremely tight manufacturing tolerances), the deformable pin is introduced as a mediator that fills the clearance space. This allows the key and keyway to be manufactured with standard tolerances while still achieving the goal of eliminating rotational play through the pin's deformed engagement
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 deformable pin effectively fixes the angular position sensor rotor relative to the motor shaft, minimizing errors and maintaining accurate motor position data, even in multi-pole motors, thereby enhancing the control and efficiency of electric traction systems.
Implementation Method 1
a deformable pin located in the axial keyway and under compression between the axial key and the keyway in the motor shaft
Implementation Method 2
a deformable pin located in the axial keyway and under compression between the axial key and the keyway in the motor shaft, the deformable pin inhibiting rotational shifting
Data Source
AI summary
An electric motor assembly includes a motor shaft rotatable about a longitudinal axis, an angular position sensor rotor, and a deformable pin. The motor shaft has an axial keyway formed therein, and the axial keyway has a nominal keyway dimension. The angular position sensor rotor is coupled to the motor shaft to rotate with the motor shaft. The angular position sensor rotor has an axial key to fit within the axial keyway of the motor shaft, and the axial key has a nominal key dimension that is less than the nominal keyway dimension. The deformable pin is located in the axial keyway under compression between the axial key and the motor shaft to inhibit rotational shifting of the angular position sensor rotor relative to the motor shaft.