Mechanical Accessory Interlock for Power Tool Safety
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Solution Overview
Problem
Existing tools with prime movers face challenges in ensuring that both types of detachable accessories are attached before the tool can be operated, as existing sensor-based systems are prone to failure and increase costs due to the need for separate sensors for each accessory.
Innovation Solution
A mechanical configuration where intermediate members block or allow the displacement of the operation member based on the attachment status of the accessories, enabling the prime mover to be driven only when both accessories are attached without using sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sensor-based detection systems are used to detect accessory attachment status, then the tool can prohibit operation when accessories are missing, but the system complexity and cost increase due to requiring separate sensors for each accessory
Solution Approach 1:
The patent replaces sensor-based detection with a purely mechanical detection system. Intermediate members are mechanically connected to accessories through attachment portions, and these intermediate members physically block or permit the operation member's movement based on whether accessories are attached. This mechanical coupling eliminates the need for sensors while maintaining reliable detection capability.
Solution Approach 2:
The patent introduces intermediate members as mechanical intermediaries between the accessories and the operation mechanism. These intermediate members transmit the attachment status information mechanically: when an accessory is attached, the intermediate member moves to a position that permits operation; when detached, it blocks operation. This intermediary mechanism simplifies the overall system by providing a direct mechanical linkage instead of requiring separate sensing and control systems.
2Reliability
If separate sensors are provided for each accessory type, then each accessory attachment can be detected individually, but the cost increases due to multiple sensor components
Solution Approach 1:
The patent implements a universal mechanical detection mechanism where a single intermediate member can detect the attachment status of different accessory types. The attachment portions are designed with universal coupling features that work with various accessories (grinding wheels, cutting discs, etc.). This universal design eliminates the need for accessory-specific sensors, reducing component variety and manufacturing cost while maintaining reliable detection across different accessory types.
3Object-affected harmful factors
If sensor-based systems are used to prevent operation without accessories, then safety is improved, but the system becomes more complex and sensitive to dust deposition affecting sensor performance
Solution Approach 1:
The patent replaces electronic sensors with a mechanical blocking mechanism that is inherently resistant to dust and environmental contamination. The intermediate members physically move to block the operation member's displacement route when accessories are missing, providing reliable safety functionality without the susceptibility of electronic sensors to dust deposition, moisture, or other environmental factors.
Data Source
AI summary
A tool includes a prime mover, switch, operation member for the switch, first accessory, second accessory, third intermediate member moved in conjunction with displacement of the operation member, first intermediate member configured to be displaced from a first blocking position of blocking a displacement route of the third intermediate member to a first non-blocking position of not blocking the displacement route by attachment of the first accessory, and second intermediate member configured to be displaced from a second blocking position of blocking the displacement route to a second non-blocking position of not blocking the displacement route by attachment of the second accessory. Only when the first intermediate member is located at the first non-blocking position and the second intermediate member is located at the second non-blocking position, the third intermediate member is permitted to be displaced so that the operation member is permitted to be displaced to the ON position.