Combustion Chamber Lockout for Fastener Tool Recoil
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Solution Overview
Problem
Combustion-powered fastener-driving tools face challenges in maintaining the combustion chamber closed during piston return, especially when the tool is lifted off the work surface or experiences recoil, leading to premature opening and loss of pressure, which affects the tool's ability to drive nails consistently.
Innovation Solution
A lockout device with a protrudable element and interfering portion is used, where the protrudable element, such as a pin, engages with the connecting member to prevent movement of the combustion chamber support bracket when the trigger is depressed, ensuring the chamber remains sealed until the trigger is released, allowing complete piston return and maintaining chamber closure during recoil.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the tool is lifted off the work surface or experiences recoil, then the combustion chamber opens prematurely, but this causes loss of pressure and affects nail driving consistency
Solution Approach 1:
The lockout device is pre-configured with a protrudable element that automatically engages with the interfering portion when the trigger is depressed, preventing chamber opening before the piston return process is complete. This preliminary locking action ensures the chamber remains sealed during any tool movement or recoil events.
Solution Approach 2:
The lockout device acts as an intermediary mechanism between the trigger and the combustion chamber support bracket. The protrudable element and interfering portion create a mechanical linkage that mediates the connection, preventing direct movement transmission that would cause premature chamber opening while allowing normal operation when engaged.
2Reliability
If the combustion chamber remains closed during piston return, then complete piston return is achieved, but this requires extended chamber closure time
Solution Approach 1:
The lockout device is automatically reset by the piston's own return motion. As the piston moves upward, it directly actuates the protrudable element to disengage from the interfering portion, causing the lockout device to reset without requiring separate control mechanisms or extended chamber closure time.
3Reliability
If the valve sleeve is restrained from moving, then the combustion chamber remains sealed, but this prevents normal valve operation
Solution Approach 1:
The lockout device dynamically transitions between two states: locked and unlocked. The protrudable element can engage with the interfering portion to prevent valve sleeve movement (locked state) or disengage to allow normal reciprocation (unlocked state). This dynamic behavior is controlled by the trigger mechanism and piston position, enabling the system to adapt between sealing and operating modes.
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
This solution ensures the combustion chamber remains sealed and allows for complete piston return, enhancing the tool's reliability and consistency in driving fasteners, even when lifted off the work surface or experiencing recoil, by automatically resetting the lockout mechanism upon trigger release.
Implementation Method 1
Combustion-powered tools utilize self-generative vacuum to perform the piston return function
Implementation Method 2
a fan located in a combustion chamber provides for both an efficient combustion within the chamber, while facilitating processes ancillary to the combustion operation of the device... cooling the engine
Implementation Method 3
A battery-powered electronic power distribution unit produces a spark for ignition
Implementation Method 4
Upon the pulling or depressing of a trigger switch, which causes the spark to ignite a charge of gas in the combustion chamber of the engine, the combined piston and driver blade is forced downward
Data Source
AI summary
A combustion-powered fastener-driving tool includes a combustion-powered power source including a cylinder head and a combustion chamber defined by the cylinder head, a valve sleeve and an upper surface of a reciprocating piston, the valve sleeve reciprocable relative to the cylinder head between a rest position and a pre-firing position. A lockout device is associated with the trigger and has an actuated position configured for preventing the reciprocation of the valve sleeve away from the pre-firing position until the trigger is released.