Electric Motor Angle Sensor with Floating Bearing and Spring PCB
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Solution Overview
Problem
Existing electric motors with integrated angle sensors face challenges in simple assembly, axial distance adjustment, thermal expansion compensation, and imbalance reduction, particularly in the design and positioning of sensors and magnets.
Innovation Solution
The electric motor incorporates a permanent magnet securely attached to the rotor shaft, a floating bearing for thermal expansion compensation, Hall and Wiegand sensors for magnetic field detection, and a compact circular printed circuit board with spring element support, eliminating the need for axial adjustment and providing a strong magnetic field for precise angle determination without galvanic isolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a permanent magnet is used for angle detection, then measurement precision is improved, but device complexity increases due to additional components and positioning requirements
Solution Approach 1:
The patent combines the angle sensor components (permanent magnet, sensors, and evaluation electronics) into a single integrated unit mounted on the end shield. This merging approach maintains high measurement precision while reducing overall device complexity by eliminating separate adjustment mechanisms and simplifying the structural arrangement of components.
Solution Approach 2:
The spring element automatically positions the printed circuit board at the correct axial distance from the rotor shaft through elastic force, eliminating the need for manual adjustment mechanisms. This self-positioning feature reduces device complexity while maintaining measurement precision through consistent spacing.
2Manufacturing precision
If axial distance adjustment mechanisms are added for precise positioning, then manufacturing precision is improved, but ease of manufacture deteriorates
Solution Approach 1:
The spring element serves as a self-adjusting mechanism that automatically positions the printed circuit board at the required axial distance from the rotor shaft. The elastic force of the spring compensates for manufacturing tolerances in the bearing and end shield, achieving precise positioning without complex adjustment mechanisms, thereby maintaining ease of manufacture.
Solution Approach 2:
The spring element allows the axial position of the printed circuit board to be dynamically adjusted based on compression, enabling the system to accommodate manufacturing tolerances and thermal expansions while maintaining precise positioning. This parameter-based approach simplifies manufacturing by eliminating the need for precision-machined adjustment features.
3Stability of the object's composition
If a fixed bearing is used for rotor support, then stability is improved, but thermal expansion compensation capability deteriorates
Solution Approach 1:
The bearing system is segmented into a fixed bearing for stability and a floating bearing for thermal compensation. The fixed bearing provides stable rotor support, while the floating bearing independently handles thermal expansion through axial movement, allowing both functions to coexist without interference.
Solution Approach 2:
The spring element acts as an intermediary between the fixed bearing side and the floating bearing, transmitting forces while allowing independent movement. This intermediary mechanism enables the fixed bearing to maintain stability while the floating bearing compensates for thermal expansion through axial displacement.
4Ease of manufacture
If the magnet is positioned away from the rotor shaft axis, then ease of manufacture is improved, but imbalance increases
Solution Approach 1:
The magnet is positioned asymmetrically in an off-center location on the rotor shaft, away from the rotational axis. This asymmetric positioning simplifies manufacturing by allowing the magnet to be mounted in a convenient location rather than requiring precise centering, while the resulting imbalance is accepted as a trade-off for manufacturing ease.
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
This design enables a simple, cost-effective, and precise assembly of the angle sensor system, reducing imbalance and thermal expansion impacts, while allowing for multiturn encoding and reliable protection of electronics, all without requiring complex adjustment mechanisms.
Implementation Method 1
with a permanent magnet on that end section of the rotor shaft which is closer to the fixed bearing is provided, with a printed circuit board being provided on the end shield of the fixed bearing, on which sensors are provided for detecting the magnetic field of the magnet
Implementation Method 2
the sensors include at least one Hall sensor and/or Wiegand sensor
Implementation Method 3
when using Wiegand sensors, ie pulse wire sensors, the signal electronics can even be supplied with electricity from the detected signals
Data Source
Figure 1
Figure 1a
AI summary
Disclosed is an electric motor comprising an angle sensor. The rotor shaft of the electric motor is mounted by means of at least two bearings, a first one of which is designed as a fixed bearing. A radially oriented permanent magnet is provided at the axial rotor shaft end lying closer to the fixed bearing. A printed circuit board on which sensors are provided for detecting the magnetic field of the magnet is disposed on the end shield of the fixed bearing. The printed circuit board is also equipped with signal electronics for evaluating the sensor signals and determining the angular position of the rotor shaft and the magnet.