Power Tool Motor Encoder Assembly for Precise Torque Estimation
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Solution Overview
Problem
Electric power tools face challenges in accurately estimating tightening torque due to the need for high precision in detecting the angle of rotation of the motor, which is not efficiently addressed by existing technologies.
Innovation Solution
A rotation detector is integrated into the electric power tool, featuring a magnetic or optical encoder with a small gap between the rotating body and position detector, and a linking rib to maintain precise alignment, ensuring accurate angle detection and robust assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a rotation detector with high precision is provided to increase the precision of estimating tightening torque, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent combines the rotation detector components (detecting body, detector, and linking rib) into an integrated assembly that is mounted directly on the motor housing. The detecting body is coupled to the motor shaft, and the linking rib structurally connects the detecting body and detector while maintaining their relative positions, thereby merging multiple functions into a unified structure that reduces overall device complexity while maintaining high measurement precision.
Solution Approach 2:
The linking rib acts as an intermediary component that maintains the positional relationship between the detecting body and the detector. It structurally connects these two components and ensures they remain at a predetermined distance from each other, enabling precise angle detection without requiring complex positioning mechanisms.
2Weight of moving object
If a built-in motor without motor case is used to reduce size and weight, then compactness and light weight are improved, but reliability deteriorates due to direct assembly on housing rib
Solution Approach 1:
The patent segments the motor assembly into distinct functional components: the motor unit, the detecting body, and the linking rib structure. This segmentation allows each component to be optimized independently - the motor can be designed for minimal weight without a case, while the linking rib provides a dedicated structural support that enhances reliability of the rotation detection system.
Solution Approach 2:
The linking rib serves as an intermediary structural element that provides reliable mounting for the rotation detector components. It connects the detecting body to the motor housing and maintains precise positional relationships, thereby ensuring reliability of the assembly without requiring a full motor case.
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 enables precise detection of motor rotation angles, enhancing the accuracy of torque estimation and maintaining the compact size and light weight of the tool by using a built-in motor without a motor case.
Implementation Method 1
A rotation detector is integrated into the electric power tool, featuring a magnetic or optical encoder
Implementation Method 2
A rotation detector is integrated into the electric power tool, featuring a magnetic or optical encoder
Data Source
Figure 1
AI summary
A motor retainer 40, 41 is provided on an inner circumferential surface of a housing 2 and retains an outer circumference of a motor unit 4. A rotation detector 12 includes a rotating body 20 attached to a motor shaft 9b and a position detector 30 that outputs a rotational position signal corresponding to a rotational position of the rotating body 20. A sensor substrate retainer 44 is provided on the inner circumferential surface of the housing 2 and retains the position detector 30 at a position facing the rotating body 20.