Motor Cover Sensor Layout for Shorter Axial Length
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Solution Overview
Problem
Existing motors face challenges in maintaining a consistent distance between the sensor and the sensing magnet for optimal sensing performance, while also ensuring reduced size in the shaft direction and preventing gap formation between rotor core caps that could lead to rigidity issues.
Innovation Solution
A motor design that includes a cover with a hole for the sensor, a sealing member to secure the sensor's position, and caps with an elastic structure to support the rotor core, ensuring a consistent gap and rigidity regardless of assembly tolerance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the thickness of the can is reduced to minimize the gap, then the gap between caps is reduced, but the rigidity of the can is insufficient for high-speed motor operation
Solution Approach 1:
The can is designed with a dynamic elastic structure that allows controlled deformation. The elastic support enables the can to adapt to assembly tolerances through elastic deformation rather than requiring extremely tight manufacturing tolerances, thus maintaining rigidity while accommodating gaps.
Solution Approach 2:
The thickness of the can is optimized to a specific range (0.15T to 0.3T) that balances rigidity and gap minimization. Additionally, the elastic support structure changes the mechanical parameters of the system, allowing the can to maintain its shape and rigidity under operational loads while accommodating assembly variations.
2Strength
If the thickness of the can is increased to secure rigidity, then the rigidity of the can is improved, but the assemblability of the caps is lowered
Solution Approach 1:
The elastic support structure allows the can to dynamically adjust during assembly, accommodating tolerance variations without requiring precision fitting. This dynamic adaptation simplifies the assembly process while maintaining structural rigidity.
Solution Approach 2:
The can thickness is optimized within a specific range (0.15T to 0.3T) that provides sufficient rigidity while maintaining assemblability. The elastic support further modifies the mechanical behavior, enabling easier assembly without compromising structural integrity.
3Length of moving object
If the distance between the sensor and sensing magnet is reduced to minimize motor size, then the motor size in shaft direction is reduced, but the sensing performance is compromised
Solution Approach 1:
The sensor is repositioned from the traditional location to the cover, utilizing the radial dimension more effectively. This spatial reconfiguration allows for optimized sensing performance while minimizing the axial length of the motor.
Solution Approach 2:
The cover is specifically designed with a hole and elastic support structure at the precise location where the sensor is mounted. This localized structural optimization ensures the sensor maintains the optimal distance from the sensing magnet, preserving sensing performance while reducing overall motor size.
4Reliability
If two separate cans are used to cover the magnets, then the magnets are protected from separation and rust, but assembly tolerance creates gaps that expose magnets and cause rust
Solution Approach 1:
The elastic support structure effectively merges the two separate cans into a unified protective system. The elastic component bridges the gap created by assembly tolerances, ensuring continuous protection of the magnets against both separation and rust.
Solution Approach 2:
The elastic support structure serves as a pre-designed compensation mechanism that anticipates and cushions against assembly tolerance variations. This elastic element absorbs the dimensional variations, preventing gap formation that would otherwise expose the magnets to harmful factors.
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 effectively reduces the motor's size in the shaft direction, maintains consistent sensing performance, and secures rigidity by preventing gap formation between the caps, thus addressing the limitations of existing motor designs.
Implementation Method 1
a circuit board including a sensor configured to detect the sensing magnet
Implementation Method 2
an elastic structure capable of elastically supporting a rotor core is implemented on caps
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
An embodiment relates to a motor which comprises: a housing; a cover disposed to cover the housing; a stator disposed in the housing; a rotor disposed inside the stator; a shaft disposed in the center of the rotor; a sensing magnet disposed at the end of the shaft; and a circuit board including a sensor for sensing the sensing magnet, wherein the sensor is disposed inside a hole formed through the cover. Therefore, in the motor, a hole is formed through the cover disposed to cover an opening of the housing and a sensor is disposed inside the hole, so that a size of an axis direction of the motor can be reduced.