Rotary Impact Tool Protection Unit Control Logic
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Solution Overview
Problem
Rotary impact tools face damage from excessive reaction forces during screw tightening and loosening, particularly when dealing with hard materials like metal, and existing solutions fail to prevent or reduce damage effectively while maintaining operability during loosening.
Innovation Solution
A rotary impact tool with a motor, impact mechanism, rotational direction setting unit, abnormal impact detection unit, and protection unit, where the protection unit is activated differently based on the rotational direction, with more stringent conditions for activation during loosening to prevent damage and ensure operability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the protection unit is activated when abnormal impact is detected during both tightening and loosening operations, then damage from abnormal impact is prevented, but the tool becomes difficult to operate when loosening screws tightened under abnormal impact conditions
Solution Approach 1:
The protective function is made dynamic by switching between two operational modes: in the first mode (tightening), the protection unit activates immediately upon detecting abnormal impact, while in the second mode (loosening), the protection unit is inhibited from activating. This dynamic adjustment of protection behavior based on operational mode resolves the contradiction between damage prevention and ease of operation.
Solution Approach 2:
The system changes the activation parameter of the protection unit based on the rotational direction setting. When the rotational direction is set to loosening (second rotational direction), the activation condition parameter is modified to prevent protection unit activation, whereas in tightening mode (first rotational direction), the normal activation condition applies. This parameter change allows the same hardware to exhibit different protective behaviors.
2Reliability
If the protection unit activates immediately upon detecting abnormal impact, then component damage is reduced, but the tool lacks adaptability to different operational contexts (tightening vs. loosening)
Solution Approach 1:
The control unit provides multi-functionality by managing both the protection unit and the operational mode recognition. It universally handles both tightening and loosening operations while applying context-appropriate protection strategies, making the system adaptable to different operational scenarios while maintaining reliable protection where needed.
Solution Approach 2:
The protective function transitions from a static, always-active state to a dynamic, context-dependent state. The control unit continuously monitors the rotational direction setting and adjusts the protection unit's activation status accordingly, enabling the system to adapt its protective behavior to match the current operational context.
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 damage from abnormal impacts and enhances the operability of loosening screws by adjusting the activation conditions of the protection unit, ensuring the tool can handle both tightening and loosening tasks without excessive damage.
Implementation Method 1
the impact mechanism intermittently applies an impact force as a momentary torque to the output shaft in the rotational direction of the output shaft
Data Source
AI summary
In a rotary impact tool according to an aspect of the present disclosure, an impact mechanism rotates an output shaft by a rotational force of a motor and, when a torque equal to or greater than a given value is externally applied to the output shaft in a direction opposite a rotational direction of the output shaft, the impact mechanism intermittently applies an impact force as a momentary torque to the output shaft in the rotational direction of the output shaft. A protection unit stops the motor or reduces a rotational speed of the motor on condition that an abnormal impact detection unit detects the abnormal impact. A control unit controls activation of the protection unit differently when the rotational direction of the motor is set to a reverse rotational direction in comparison with when the rotational direction of the motor is set to a forward rotational direction.