Disc-Rotor EC Motor Bearing Layout for Compact Axial Support
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Solution Overview
Problem
Conventional electronically commutated motors with disc-shaped rotors face challenges in efficiently managing radial and axial forces, leading to increased complexity and cost in bearing systems, while also requiring effective cooling to prevent overheating.
Innovation Solution
The motor design features a disc-shaped rotor with a magnetization means and annular stator, utilizing two adjacent bearings for axial support, which allows for the use of inexpensive bearings and simplifies thermal stress compensation, along with a radially directed fan wheel for active cooling, and an optional signal transmitter for efficient commutation and torque transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If double-sided bearing is used to support disc-shaped rotor, then rotor support reliability is improved, but axial length of motor is increased
Solution Approach 1:
The patent transitions from a double-sided bearing arrangement (occupying axial space on both sides of the rotor) to a single-sided bearing arrangement where two bearings are stacked axially adjacent to each other on one side of the rotor. This dimensional reorganization reduces the axial length while maintaining the dual-bearing support structure, effectively resolving the contradiction between reliability and compactness.
2Reliability
If expensive precision bearings are used to handle radial forces, then bearing reliability is improved, but manufacturing cost is increased
Solution Approach 1:
The patent segments the bearing functions by using two adjacent bearings on one side of the rotor instead of requiring single high-capacity bearings. This segmentation allows the use of cheaper standard bearings that can handle radial forces adequately when working in combination, thereby reducing manufacturing cost while maintaining reliability.
Solution Approach 2:
The patent employs inexpensive standard bearings rather than expensive precision bearings. By using multiple affordable bearings in an axial arrangement, the system achieves the required reliability without the high cost of premium components, effectively applying the principle of using cheap, replaceable parts to achieve reliable performance.
3Device complexity
If thermal expansion is not compensated, then device simplicity is maintained, but operational reliability deteriorates due to thermally induced mechanical stresses
Solution Approach 1:
The patent enables the bearing system to self-compensate for thermal expansion through its axial arrangement. The adjacent bearings naturally accommodate thermally induced mechanical stresses without requiring external compensation mechanisms, allowing the system to maintain reliability while preserving simplicity. The structure itself provides the thermal compensation function.
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 configuration results in a compact, high-torque motor with reduced magnetic losses, effective thermal management, and simplified integration into handheld tools, enabling efficient power transmission with low friction and weight savings.
Implementation Method 1
each stator tooth is provided with a stator tooth winding which is configured in each case to interact magnetically with the magnetization means of the rotor
Implementation Method 2
a radially directed fan wheel for active cooling
Data Source
AI summary
In the case of an electronically commutated motor with a disc-shaped rotor which has an associated magnetization means and a rotor shaft, and with an annular stator, on which a plurality of stator teeth are provided, wherein each stator tooth is provided with a stator tooth winding, each of which is configured to interact magnetically with the magnetization means of the rotor, and wherein the rotor shaft reaches through the stator in the axial direction, the rotor shaft is mounted rotatably via at least two bearings which are arranged on the rotor shaft directly next to one another in the axial direction of the rotor shaft.