Mechanical Trigger Timer Assembly for Bump-Mode Fastener Driving
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Solution Overview
Problem
Existing fastener driving tools with bump mode require electrical components for timing mechanisms, which are costly and problematic for non-electrically driven tools like pneumatic fastener driving tools.
Innovation Solution
A mechanical timer mechanism using a rotary damper, driven gear, and drive gear with a one-way clutch to control the operation mode, allowing for a bump mode that times out without electrical components, and a mode selector to switch between sequential and bump modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an electronic timer mechanism is used to control bump mode timing, then the timing control function is achieved, but the device complexity and cost increase due to electrical components in non-electrically driven tools
Solution Approach 1:
The patent replaces the electronic timer mechanism with a purely mechanical timing system consisting of a spring-driven cam mechanism. The cam rotates at a controlled rate and automatically returns the contact trip to the home position after a predetermined time interval, eliminating the need for electrical components in pneumatic tools while maintaining reliable timing control.
Solution Approach 2:
The patent extracts the timing function from the electronic control system and implements it as a separate mechanical subsystem. The cam mechanism is independently driven by a spring and operates autonomously to control the contact trip timing, separating the timing function from the main pneumatic and electrical systems.
2Productivity
If bump mode allows continuous fastener driving until trigger release, then productivity increases, but the risk of inadvertent actuations increases
Solution Approach 1:
The patent implements a preliminary action by requiring the contact trip to be manually moved to the actuating position before each fastener drive in sequential mode. This manual engagement step serves as a deliberate action that prevents inadvertent actuations, while the system still supports continuous operation in bump mode when the contact trip is held in the actuating position.
Solution Approach 2:
The patent provides dynamic operation modes that allow the system to switch between sequential mode (requiring deliberate manual engagement for each shot) and bump mode (allowing continuous operation). This dynamic switching capability enables the system to adapt to different work requirements while maintaining safety through the sequential mode option.
3Ease of manufacture
If a mechanical timer mechanism is used instead of electronic components, then cost and complexity are reduced for pneumatic tools, but the precision of timing control may be compromised
Solution Approach 1:
The patent uses parameter changes by adjusting the spring tension and cam geometry to precisely control the timing interval. The spring constant, cam rotation speed, and cam profile shape are optimized to achieve the desired timing precision, allowing the mechanical system to match or exceed electronic timing accuracy while maintaining manufacturing simplicity.
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
Enables efficient operation in both sequential and bump modes without electrical components, ensuring timely reversion of the bump mode and preventing inadvertent actuations, thus providing cost-effective and reliable fastener driving.
Implementation Method 1
a rotary damper coupled to a tool housing, the rotary damper having a damper shaft
Implementation Method 2
A one-way clutch is coupled to the damper shaft between the damper shaft and the driven gear to transfer rotation of the driven gear to the damper shaft in the first direction, but not in the second direction
Data Source
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AI summary
A mechanical timer mechanism can include a driven gear mounted to a rotary damper and a drive gear operably coupled to the driven gear. In bump mode, movement of an auxiliary trigger to its actuating position can initially move the drive gear from a home position into its wind-up position. Thereafter, a contact trip can continue to move the drive gear to its wind-up position and an actuator of a principal trigger to its actuating position each time the contact trip is actuated, unless the timing mechanism has timed-out between actuations. In sequential mode, the drive gear can be moved into a timer lock- out position which holds the contact trip in a bypass position in which the contact trip will not engage the actuator of the auxiliary trigger unless the auxiliary trigger is moved to its actuating position before actuation of the contact trip.