Mechanical Timer Mechanism for Pneumatic Fastener Tool Bump Mode Timeout
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Solution Overview
Problem
Pneumatic fastener driving tools lack a cost-effective mechanism to time out of bump mode, posing safety concerns due to the complexity and cost of adding electronic timers.
Innovation Solution
A mechanical timer mechanism using a drive gear and rotary damper with a one-way clutch, coupled with a timer spring and wind-up arm, automatically reverts the tool from bump mode after a predetermined time, ensuring user safety without electrical components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an electronic timer mechanism is added to pneumatic fastener driving tools to enable bump mode timeout, then the safety and operational control are improved, but the device complexity and manufacturing cost increase significantly
Solution Approach 1:
The patent replaces the electronic timer mechanism with a purely mechanical timing system consisting of a mainspring, drive gear, and ratchet mechanism. The mainspring provides the timing function through its controlled unwinding, eliminating the need for electronic components while achieving the same bump mode timeout control. This mechanical substitution directly resolves the contradiction by maintaining reliability through a simpler, more robust mechanical system.
Solution Approach 2:
The mechanical timer mechanism is self-powered through the tool's existing pneumatic system. The drive gear is advanced by pneumatic pressure from the tool's motor, which automatically winds the mainspring and advances the timing mechanism during operation. This self-service approach eliminates the need for separate power sources or complex electronic control systems, reducing device complexity while maintaining reliable timeout control.
2Reliability
If an electronic timer mechanism is added to pneumatic fastener driving tools to enable bump mode timeout, then the operational safety is improved, but the manufacturing cost increases
Solution Approach 1:
The patent replaces expensive electronic timer components with inexpensive mechanical parts including a mainspring, drive gear, and ratchet mechanism. These mechanical components are simpler to manufacture, require fewer precision electronics, and can be produced using traditional manufacturing methods, significantly reducing manufacturing costs while maintaining the essential bump mode timeout safety function.
Solution Approach 2:
The mechanical timer mechanism uses simple, easily replaceable components that can be manufactured at low cost. If wear or failure occurs, the entire timer assembly or individual components can be quickly replaced without requiring expensive electronic diagnostics or specialized manufacturing processes, reducing both initial manufacturing cost and long-term maintenance costs.
3Reliability
If the trigger must be released and reengaged for continued bump mode operation after timeout, then user safety is improved, but the ease of operation decreases
Solution Approach 1:
The mechanical timer mechanism provides automatic feedback to the operator through the trigger mechanism. When the predetermined time interval expires, the drive gear can no longer advance the wind-up arm, which automatically causes the trigger to return to its unengaged position. This feedback mechanism ensures user safety by preventing continuous operation beyond the safe time limit, while the automatic trigger return minimizes the operational burden on the user.
Solution Approach 2:
The bump mode operation is naturally limited to periodic intervals through the mechanical timer. The tool operates in bump mode only for the predetermined time period, then automatically times out and requires a new trigger engagement to restart the timing cycle. This periodic action ensures safety by preventing indefinite continuous operation, while the straightforward trigger pull-release-pull sequence remains simple for users to follow.
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 mechanical timer mechanism effectively times out the bump mode, enhancing user safety by requiring trigger re-engagement for continued operation, while avoiding the costs and complexities of electronic timers.
Implementation Method 1
a rotary damper (54) that provides viscous damping to a rotation of the drive gear (50)
Implementation Method 2
a one-way clutch (60) that allows rotation of the driven gear (56) in a first direction, but that prevents rotation of the driven gear (56) in a second direction
Implementation Method 3
a timer spring (74) that stores and releases energy to rotate the drive gear (50)
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
A mechanical timer mechanism (20) can include a driven gear (56) mounted to a rotary damper (54) and a drive gear (50) operably coupled to the driven gear (56). In bump mode, movement of a trigger (24) to its firing position can initially move the drive gear (50) into its wind-up position. Thereafter, a contact trip (64) can move the drive gear (50) to its wind-up position and an actuator (28) of the trigger (24) to its firing position each time the contact trip (64) is activated, unless the timing mechanism (20) has timed out between firings. In sequential mode, the drive gear (50) can be moved into a timer lock-out position which holds the contact trip (64) in a bypass position in which the contact trip (64) will not engage the actuator (28) of the trigger (24) unless the trigger (24) is moved to its firing position prior to activation of the contact trip (64).