Combustion Fastener Tool Electronic Timing Control
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Solution Overview
Problem
Combustion-powered setting tools with thermal return of the setting piston face issues where the combustion chamber can be inadvertently reopened too quickly, allowing for potential reactivation with the tool still pressed against a substrate, leading to unsafe operation.
Innovation Solution
An electronic control unit with an initialization switch and time comparator ensures that ignition is only enabled if the time between switching the initialization switch and the trigger switch is within a predetermined short time frame, preventing accidental reactivation after the tool has been locked.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the combustion chamber is locked with the trigger pulled before ignition, then the combustion chamber remains closed until the setting piston returns, but the tool can be inadvertently reactivated when pressed against a substrate and trigger is pulled again
Solution Approach 1:
The control unit monitors the state of both the initialization switch and trigger switch, and based on this feedback, determines whether to enable ignition. The system continuously checks the timing relationship between switch activations and prevents ignition when the time interval exceeds the predetermined threshold, thereby avoiding inadvertent reactivation while maintaining reliable control.
Solution Approach 2:
The patent replaces purely mechanical locking mechanisms with an electronic control system that uses temporal logic to manage combustion chamber locking and ignition enablement. Instead of relying solely on mechanical trigger positioning, the electronic system monitors switch states and time intervals to control ignition, providing more precise and reliable safety control.
2Reliability
If a delay is provided in trigger movement to prevent premature opening of combustion chamber, then the chamber remains closed longer, but the tool cannot be quickly ready for next operation
Solution Approach 1:
The system dynamically adjusts the ignition enablement state based on real-time trigger position and timing conditions. The control unit continuously evaluates whether the current moment satisfies the ignition conditions by checking if the trigger switch was activated within the predetermined time threshold after the initialization switch, allowing the system to be ready for ignition as soon as proper conditions are met without unnecessary delays.
Solution Approach 2:
The patent introduces a time parameter (predetermined time threshold) that defines the window for valid trigger activation. By monitoring whether the trigger switch is actuated within this time parameter after initialization, the system ensures proper sequencing without imposing fixed mechanical delays, thus maintaining both reliability and operational responsiveness.
3Ease of operation
If the initialization switch can be actuated before locking, then the system is more flexible, but accidental activation risk increases
Solution Approach 1:
The initialization switch can be actuated in advance to prepare the system, but the control unit stores this state and waits for proper trigger activation within the time threshold. This preliminary action allows the operator to ready the tool without immediately enabling ignition, and the system maintains this prepared state safely until the proper triggering sequence occurs, preventing accidental activation while preserving operational flexibility.
Solution Approach 2:
The control unit acts as an intermediary between the initialization switch and the ignition system. It receives signals from both switches, evaluates the temporal relationship between them, and only enables ignition when the proper sequence and timing are confirmed. This intermediary logic prevents direct coupling that would allow accidental activation while maintaining the flexibility of separate switch actuation.
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 effectively prevents the setting tool from being triggered when it has been pressed against a substrate and locked, ensuring safe operation by limiting the time window for ignition activation, thus preventing unintended reactivation.
Implementation Method 1
A combustion chamber (13) in which a portion of liquid gas or other vaporizable fuel with an oxidizing agent such as ambient air is combustible
Implementation Method 2
an electric spark is generated, which causes a gas mixture in the combustion chamber, such as e.g. B. an air-fuel gas mixture ignites and thus starts the combustion process
Data Source
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AI summary
The device has a locking device (37) for locking a valve unit into a position of an intake/exhaust arrangement (40). A triggering switch (22) is switchable depending on a position of an outlet (30), and is provided for triggering ignition in a combustion chamber (13). An initialization switch is connected with an electronic control unit (20). The control unit releases injection into the combustion chamber only when a period between a switching of the initialization switch and a switching of the triggering switch is not longer than a given target time.