Electric Machine Bearing Mounting for Axial and Radial Force Control
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Solution Overview
Problem
Electric machines, such as brushless motors, face challenges in withstanding large forces at high operating speeds, which affects their performance and reliability over time.
Innovation Solution
The electric machine design incorporates a rotor assembly with a shaft-mounted first bearing adhesively fixed to a support body and a second bearing soft-mounted using an o-ring, allowing effective absorption of axial and radial forces, respectively, thereby enhancing the motor's ability to withstand operational forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single bearing mounting method is used, then the structure is simple, but the motor cannot effectively withstand both axial and radial forces at high speeds
Solution Approach 1:
The bearing support structure is segmented into two distinct mounting methods: the first bearing is fixed to the support body using adhesive, while the second bearing is soft-mounted using an O-ring. This segmentation allows each bearing to be optimized for different force types, with the adhesive-mounted bearing handling axial forces and the soft-mounted bearing absorbing radial forces, thereby resolving the contradiction between reliability and structural simplicity.
Solution Approach 2:
Different local qualities are applied to different bearings based on their specific force requirements. The first bearing location uses a rigid adhesive bond suitable for axial force transmission, while the second bearing location uses a compliant O-ring mounting suitable for radial force absorption. This local differentiation enables the overall system to withstand high-speed operational forces effectively without requiring complete structural redesign.
2Strength
If adhesive is used to mount the bearing, then axial forces are withstood effectively, but radial forces can weaken the adhesive bond
Solution Approach 1:
The bearing mounting system is segmented so that axial force resistance and radial force absorption are handled by different mounting mechanisms. The adhesive-mounted first bearing provides strong axial force resistance, while the O-ring soft-mounted second bearing handles radial forces, preventing bond weakening and ensuring long-term reliability.
3Force
If the bearing closest to the load is soft-mounted, then radial forces are absorbed effectively, but axial forces need to be withstood by the other bearing
Solution Approach 1:
The bearing closest to the load (second bearing) is soft-mounted with an O-ring to provide local radial force absorption capability, protecting the adhesive bond from radial stress. The first bearing, positioned further from the load, is adhesive-mounted to provide axial force resistance. This local quality differentiation resolves the contradiction between force absorption effectiveness and mounting complexity.
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 effectively distributes force absorption, preventing adhesive bond weakening and ensuring the motor's longevity by utilizing different mounting methods for bearings, thereby improving the motor's performance and reliability at high speeds.
Implementation Method 1
the first bearing is mounted to the first bearing seat by adhesive
Implementation Method 2
the second bearing is soft-mounted to the second bearing seat by an o-ring
Data Source
AI summary
An electric machine comprising: a stator assembly; a rotor assembly; and a support body. The rotor assembly comprises a shaft to which is mounted a first bearing and a second bearing either side of a permanent magnet, and the support body comprises first and second bearing seats to which the bearings of the rotor assembly are mounted, wherein the first bearing is mounted to the first bearing seat by adhesive, and the second bearing is soft-mounted to the second bearing seat by an o-ring.