Rotary Impact Tool Sensing for Precise Hammer-Anvil Impact Control
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Solution Overview
Problem
Existing rotary impact tools face challenges in accurately detecting and controlling the rotational position and impact frequency of the anvil and hammer components, leading to inefficiencies in torque delivery and fastening operations.
Innovation Solution
Incorporation of printed circuit board assemblies with sensors to detect the rotation and translation of the anvil and hammer, along with a thrust bearing system to maintain a gap between the anvil lugs and the sensors, allowing precise control of impact frequency and torque delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sensors are placed close to the anvil and hammer components for detection, then measurement precision improves, but the risk of damage from impact forces increases
Solution Approach 1:
A non-magnetic spacer is introduced as an intermediary component between the sensors and the anvil/hammer components. This spacer maintains a precise gap that allows the sensors to detect rotational position and impact events accurately while preventing direct contact between the sensors and the high-stress impact components, thereby eliminating impact damage risk.
Solution Approach 2:
The sensor assembly is segmented from the impact path by placing it on a separate PCB assembly that is axially offset from the anvil and hammer components. This spatial segmentation allows the sensing function to be isolated from the impact zone, enabling precise measurement without exposing sensors to harmful impact forces.
2Device complexity
If the printed circuit board assembly is positioned close to the anvil for compact design, then device complexity reduces, but manufacturing precision requirements increase to ensure proper gap spacing
Solution Approach 1:
A non-magnetic spacer serves as a precision positioning intermediary that is integrated into the PCB assembly or housing. This spacer provides a mechanically defined gap distance that is insensitive to variations in anvil position or PCB mounting tolerance, thereby reducing the stringency of manufacturing precision requirements while maintaining compact dimensions.
Solution Approach 2:
The gap spacing is pre-established through the mechanical design of the spacer and housing features during assembly, rather than relying on post-assembly adjustments or tight tolerances. This preliminary positioning action ensures proper sensor-to-anvil spacing is achieved through straightforward assembly operations.
Data Source
AI summary
A rotary impact tool including a motor housing, an electric motor supported in the motor housing, and a drive assembly for converting a continuous torque input from the motor to consecutive rotational impacts upon a workpiece. The drive assembly includes an anvil including an anvil lug, and a hammer that is both rotationally and axially movable relative to the anvil. The hammer includes a hammer lug for imparting the consecutive rotational impacts upon the anvil lug. The rotary impact tool further includes a first printed circuit board assembly including an anvil sensor, a first carrier supporting the first printed circuit board assembly, a second printed circuit board assembly including a hammer sensor, and a second carrier supporting the second printed circuit board assembly.