Dust Extractor Flap Stop for Handheld Power Tool Backflow Control
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Solution Overview
Problem
Existing handheld power tools with dust extractors face issues with unwanted return flow of dust from the dust box back into the tool, particularly due to pressure changes and deformation of sealing flaps.
Innovation Solution
Incorporating an adjustable closing flap with a linear or two-dimensional stop in the tubular portion of the dust extractor, which is held pivotably against the inner wall and stabilized by a spring wire or integral step, preventing the flap from opening and allowing the dust to flow into the dust box while maintaining a secure closure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sealing flaps are used to prevent dust return flow, then dust containment is improved, but the sealing flaps may deform under pressure changes and fail to maintain closure
Solution Approach 1:
A stop element is introduced as an intermediary component between the closing flap and the tubular portion. This stop provides a fixed reference point that prevents the closing flap from deforming under pressure changes. The stop acts as a mediator that maintains the geometric stability of the closing mechanism while allowing the flexible sealing flap to function effectively.
Solution Approach 2:
The invention changes the geometric parameters of the closing mechanism by introducing a stop with specific dimensional characteristics. The stop extends at an angle to the flow direction and creates a stop line or stop area that defines the closing position. This parameter change ensures the closing flap maintains its shape and sealing effectiveness under varying pressure conditions.
2Stability of the object's composition
If a rigid stop is used to prevent flap deformation, then flap stability is improved, but the device complexity increases
Solution Approach 1:
The stop is merged with the tubular portion as an integrated feature rather than a separate component. The stop can be formed as an extension or modification of the tubular portion's wall structure, reducing the total number of parts. This merging approach maintains flap stability while minimizing device complexity.
Solution Approach 2:
The tubular portion serves multiple functions: it guides dust flow, provides structural support, and incorporates the stop feature to stabilize the closing flap. By making the tubular portion multi-functional, the invention avoids adding separate components and keeps the overall device complexity low.
3Ease of operation
If the closing flap is allowed to pivot freely, then ease of operation is improved, but unwanted opening motion occurs causing dust return flow
Solution Approach 1:
The closing mechanism is segmented into distinct functional zones: the pivot area that allows free motion for ease of operation, and the stop contact area that prevents unwanted opening. The stop creates a defined closing position where the flap rests with linear or two-dimensional contact, separating the freedom of motion from the constraint needed for reliable sealing.
Solution Approach 2:
The closing flap maintains dynamic characteristics by being pivotably mounted, allowing it to respond to pressure changes and operational needs. The stop provides a dynamic constraint rather than a fixed constraint, allowing the flap to move freely during normal operation while preventing unwanted opening motions that would cause dust return flow.
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 configuration effectively prevents dust return flow by stabilizing the closing flap, allowing soft elastic materials to be used without deformation, ensuring reliable dust containment even under pressure reversals and varying operating positions.
Implementation Method 1
even comparatively soft closing flaps can be used without the risk that the closing flap will be deformed in an unwanted way... Soft elastic closing flaps in particular can be used, which are made for instance from a sealing material such as rubber
Data Source
AI summary
A hand-held power tool is equipped with a dust extraction device which includes a dust box for holding dust. A closing flap is arranged in a tube section which lies in the flow path to the dust box, and this closing flap can be adjusted between the closed position and the open position. The closing flap is pivotably held in the region of the inner wall of the tube section and can be opened in the direction of the dust box. In the closed position, the closing flap bears against a stop which protrudes into the tube section, extends at an angle with respect to the direction of flow through the tube connection piece, and forms a stop line or stop area against which the closing flap correspondingly bears.