Moving-Coil Linear Motor with Fixed Magnet and Internal Shielding
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Solution Overview
Problem
In linear vibration motors, the magnet within the suspension component tends to deviate due to external magnetic fields, causing vibration failure and noise, as traditional solutions like shield plates can lead to uneven forces and collisions with the housing.
Innovation Solution
A moving-coil structured linear motor design where the magnet is fixed stationary on the housing, and the coil is suspended with an elastic member, allowing electromagnetic interaction to drive the mass block in a horizontal direction, minimizing vertical deviations and noise through a flexible electric current injection assembly and accommodation cavity design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If shield plates with high magnetic conductivity are fixed onto the housing surface to shield external magnetic field influence, then the deviation degree of the suspension component toward the housing is minimized, but the shield plates attract the magnet within the suspension component causing uneven forces and vertical movement that leads to collision with the housing
Solution Approach 1:
The patent inverts the traditional shield plate configuration by placing the high magnetic conductivity shield plates inside the accommodation cavity rather than outside the housing. This reversal allows the shield plates to protect the magnet from external magnetic fields without creating harmful attraction forces that cause collision noise. The internal placement changes the spatial relationship between the shield plates and the magnet, eliminating the harmful effect while preserving the shielding function.
Solution Approach 2:
The patent introduces an elastic member as an intermediary between the magnet and the housing. This elastic member absorbs and compensates for any residual attraction forces, preventing direct collision between the magnet and housing. The intermediary element acts as a buffer that maintains the magnet's position while accommodating minor force variations.
2Ease of operation
If the magnet is made movable to enable vibration function, then the motor can generate vibration feedback, but the magnet tends to deviate from its normal balance position under external magnetic field attraction
Solution Approach 1:
The patent segments the magnetic system into two independent parts: a stationary magnet fixed to the housing and a movable coil assembly that generates vibration. This segmentation allows the magnet to remain stable and unaffected by external magnetic fields, while the coil assembly performs the vibration function. The functional separation resolves the contradiction by assigning different roles to different components.
Solution Approach 2:
The patent replaces the traditional mechanical vibration generation method (moving the magnet) with an electromagnetic method (moving the coil). By using electromagnetic interaction between the stationary magnet and the energized coil, the system achieves vibration without physically moving the magnet, thus maintaining magnetic position stability while preserving vibration functionality.
3Object-affected harmful factors
If shield plates are placed on both sides of the suspension component to provide magnetic shielding, then external magnetic field influence is reduced, but it is very difficult to arrange the magnet such that the attraction forces of the two shield plates are exactly equal causing uneven force
Solution Approach 1:
The patent extracts the harmful attraction force effect by removing the shield plates from their traditional external positions and relocating them inside the accommodation cavity. This extraction eliminates the problematic force balance issue while preserving the essential magnetic shielding function. The shield plates continue to protect against external magnetic fields but no longer create uneven attraction forces on the magnet.
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 prevents vertical deviations and noise by maintaining the magnet's stationary position, ensuring stable vibration and miniaturization of the motor, while the flexible components and electrode spring ensure reliable electric current transmission and vibration frequency adjustment.
Implementation Method 1
when the coil is energized, the electromagnetic interaction between the coil and the magnet generates an electromagnetic force to drive the mass block with the coil to vibrate back and forth
Implementation Method 2
a mass block suspended in the accommodation space of the housing by an elastic member
Data Source
AI summary
The present invention provides a linear motor, wherein, a coil is fastened on a mass block that is suspended inside a housing, and a magnet is fastened on the housing and thus does not move during use. In the linear motor of the present invention, the design route that utilizes coil motion to drive mass block motion is different from the traditional route that utilizes magnet motion to drive mass block motion, thereby the traditional “moving-magnet type” is changed into “moving-coil type” of the present invention. When the linear motor provided by the present invention is used in a highly magnetic environment, even if magnetic shield plates for shielding external magnetic induction lines are glued on both outer sides of the housing, because the magnet is fixed stationary itself, no vertical deviation of the magnet due to influence of the shield plates like in the prior art occurs. Meanwhile, even if the magnetic shield plates exert vertical forces on the coil, because such forces exerted by the shield plates on the coil are very small, they are hardly able to drive the coil to move in the vertical direction, and thus no vertical deviation of the coil is caused, so that vibration noise is avoided.