Chamber Member Retaining Assembly for Reliable Bump Fire Sealing

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Solution Overview

Problem

Combustion-powered fastener-driving tools face issues such as premature unsealing of the combustion chamber, leading to improper function and operator fatigue due to limited operational modes, particularly when attempting to use the bump fire mode.

Innovation Solution

Incorporation of a chamber member retaining assembly controlled by a controller, which includes an electromagnet to maintain the chamber member in a sealed position until the piston fully returns to its pre-firing position, enabling operation in both sequential and bump fire modes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the chamber member is allowed to move freely to unseal the combustion chamber, then the tool can operate in bump fire mode, but the combustion chamber may unseal prematurely before the piston returns to pre-firing position, causing improper function

Engineering Contradiction:

Improveoperational modesVSAvoidchamber sealing

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The chamber member retaining assembly dynamically adjusts the chamber member's position based on piston location. The electromagnet engages to hold the chamber member in the sealed position when the piston is in the firing position, and disengages when the piston returns to the pre-firing position, allowing the chamber member to move to the unsealed position. This dynamic control enables reliable operation in both sequential and bump fire modes.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent replaces purely mechanical linkage control of the chamber member with an electromechanical system. The electromagnet provides controlled magnetic force to hold the chamber member in the sealed position, replacing what would otherwise require complex mechanical linkages to ensure the chamber remains sealed until the piston fully returns to the pre-firing position.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If the chamber member is held in sealed position using an electromagnet, then premature unsealing is prevented, but the device complexity increases

Engineering Contradiction:

Improvechamber sealingVSAvoidretaining assembly

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces complex mechanical linkages with a simpler electromagnet-based system. Instead of using multiple mechanical components to ensure the chamber member remains sealed until the piston returns to the pre-firing position, a single electromagnet provides the necessary holding force, reducing mechanical complexity while improving reliability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The electromagnet acts as an intermediary between the control system and the chamber member. It receives electrical signals from the controller and translates them into mechanical holding force, providing a clean separation between control logic and mechanical action. This intermediary approach simplifies the overall system by allowing electronic control without direct mechanical coupling.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Speed

If the chamber member is unsealed before the piston returns to pre-firing position, then the tool responds quickly to operator input, but vacuum pressure is lost and the piston stops before reaching pre-firing position

Engineering Contradiction:

Improveresponse speedVSAvoidpiston retraction

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

The system performs preliminary action by holding the chamber member in the sealed position during the piston's return to the pre-firing position. The electromagnet maintains sealing until the piston is fully retracted, ensuring vacuum pressure is maintained throughout the retraction process. This prevents premature unsealing and ensures the piston completes its return stroke, enabling reliable bump fire operation.

Inventive Principle:

Principle #10Preliminary action

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

Ensures consistent tool function by maintaining chamber sealing until the piston is fully retracted, allowing for efficient operation in both sequential and bump fire modes, reducing operator fatigue.

Implementation Method 1

an electromagnet to maintain the chamber member in a sealed position

Methodology Applied

Scientific EffectElectromagnet: Electromagnet

Implementation Method 2

a spark plug to spark and ignite the fuel/air mixture in the combustion chamber. This generates high-pressure combustion gases that expand and force the piston to move through the cylinder

Methodology Applied

Scientific EffectCombustion: Combustion

Implementation Method 3

the piston passes exhaust check valves defined by the cylinder, and some of the combustion gases that propel the piston exhaust through these check valves to atmosphere

Methodology Applied

Scientific EffectCheck valve: Valve

Data Source

PatentUS20260027686A1Fastener-driving tool with chamber member retaining assembly

Publication Date: 2026.01.29 ILLINOIS TOOL WORKS INC

AI summary

A combustion-powered fastener-driving tool that includes a chamber member retainer assembly configured to enable the controller of the tool to prevent the chamber member of the tool from moving to an open unsealed position and to ensure the tool's combustion chamber remains sealed until the piston fully returns to its pre-firing position.