BLDC Vibration Motor Cogging Plate Optimization
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Solution Overview
Problem
Conventional BLDC vibration motors face challenges in miniaturization, with limited eccentric weight size and bonding force, cogging plate detachment, weakened supporting force, and residual vibrations, which hinder their performance and reliability in small electronic devices.
Innovation Solution
The design enhances the eccentric weight mounting structure for increased vibration force, stabilizes the coupling between the eccentric weight and back yoke, optimizes cogging plate mounting to prevent detachment and improve stopping speed, and reduces friction noise by optimizing cogging plate area and arrangement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the eccentric weight size is increased to improve vibration force, then the vibration force is improved, but the device size increases and miniaturization is hindered
Solution Approach 1:
The patent utilizes an eccentric weight as a counterweight component in the rotor assembly. By positioning the eccentric weight off-center relative to the rotor axis, it creates unbalanced centrifugal forces during rotation that generate vibration. The weight is strategically placed between the magnet and the side wall of the upper case to maximize vibration force while maintaining compact dimensions.
2Reliability
If the bonding force between eccentric weight and back yoke is increased to prevent detachment, then reliability is improved, but manufacturing complexity increases
Solution Approach 1:
The patent employs a curved or arc-shaped bonding surface between the eccentric weight and the back yoke instead of a flat interface. This curved geometry increases the bonding area and improves mechanical interlocking, thereby enhancing the bonding reliability and preventing detachment under centrifugal forces during high-speed rotation, while maintaining a relatively simple manufacturing process.
3Power
If cogging plates are inserted into through holes to improve rotation torque, then starting performance is improved, but cogging plates may detach under external impact
Solution Approach 1:
The patent divides the cogging plate structure into multiple segments or teeth that are distributed around the rotor periphery. Each segment interacts with the magnet to generate cogging torque, distributing the mechanical stress and improving starting performance. The segmented structure also allows better accommodation within the bracket while maintaining stability against external impacts.
4Stability of the object's composition
If cogging plate area is increased to improve supporting force, then rotor stability is improved, but friction noise increases during startup
Solution Approach 1:
The patent optimizes the local geometry and distribution of the cogging plate teeth, making each tooth precisely shaped and positioned to minimize contact area with the rotor during startup while maintaining adequate supporting force. The local quality of the cogging plate surface and tooth profile is engineered to reduce friction and noise generation during the initial rotation phase.
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 results in a more robust and efficient vibration motor with increased vibration force, improved reliability against external impacts, and reduced manufacturing costs, eliminating the need for separate noise prevention measures.
Implementation Method 1
generates vibrations by converting electrical energy into mechanical energy based on a principle of generating an electromagnetic force
Implementation Method 2
interaction between a magnetic field formed by the stator and a magnetic field formed by the rotor
Implementation Method 3
the cogging plates can generate a cogging torque and interact with the magnet of the rotor so that the rotor can be stopped at a specific position
Data Source
AI summary
Disclosed is a brushless DC vibration motor. An eccentric weight of a rotor is securely sandwiched between a back yoke and a permanent magnet, being heavier to provide an increased vibrational force. A bearing coupling portion with upper and lower stopping protrusions prevents detachment of a bearing. A bracket is formed with grooves, instead of through holes, to strongly support a cogging plate of which pieces are connected with each other to form a single body for easy-placement on the bracket. An optimized area of the cogging plate can suppress the rotor not to rise during starting of the motor, resulting in no frictional noise, and a high stopping speed and uniform horizontal level of the rotating rotor.