Dishwasher Filter Openings With Gradated Walls for Lower Flow Resistance
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Solution Overview
Problem
Existing dishwasher filter combinations are difficult to produce efficiently, leading to increased flow resistance and material inefficiencies due to sharp-cornered transitions and mold offsets during the plastic injection molding process.
Innovation Solution
A filter element with a gradated inner wall contour and hexagonal filter openings, featuring a widening cross-section in the flow direction and an annular surface offset to compensate for mold offsets, reduces flow resistance and allows for a denser arrangement of filter holes without reducing material thickness, enhancing rigidity and production simplicity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the filter element is produced using conventional plastic injection molding with straight-walled filter openings, then the production process is simple, but sharp-cornered transitions are formed at the demoulding plane which increase flow resistance
Solution Approach 1:
The patent applies curvature by forming rounded transitions at the sharp corners of the filter openings. Specifically, the inner wall of the filter opening features a gradation that creates curved surfaces instead of sharp corners, which reduces flow resistance while maintaining compatibility with conventional injection molding processes. The rounded corners eliminate the harmful sharp-cornered transitions that would otherwise form at the demoulding plane.
Solution Approach 2:
The patent applies local quality by introducing a gradation specifically at the critical regions where sharp corners would form (the demoulding plane and corner regions), while maintaining the overall simple cylindrical structure of the filter openings. This localized modification of the wall thickness or contour at specific positions reduces flow resistance without complicating the overall manufacturing process or filter structure.
2Reliability
If the number of screen holes in the fine filter is increased to improve filter performance, then filtering capability is enhanced, but flow resistance increases
Solution Approach 1:
The patent applies parameter changes by modifying the geometric parameters of the filter openings, specifically the contour profile and corner radii. By changing the shape parameters (rounded corners, gradation in wall contour) rather than the number or size of holes, the patent improves flow characteristics without sacrificing filter performance. This allows the filter to maintain high filtering capability while reducing the harmful flow resistance that would otherwise increase with more screen holes.
3Ease of manufacture
If mold offsets are not compensated for during injection molding, then production tolerances are simpler, but offset corners are formed that increase flow resistance
Solution Approach 1:
The patent applies preliminary action by pre-compensating for mold offsets in the design phase. The gradation and rounded corner design are specifically configured to accommodate and compensate for expected mold offsets before production begins. This preliminary consideration in the design allows the filter to maintain smooth flow paths even when mold offsets occur during manufacturing, eliminating the need for tight tolerance control while preventing offset corner formation.
Data Source
AI summary
A water-conducting household appliance, in particular a dishwasher, includes a hydraulic circuit for circulation of a wash fluid, and a filter facility which includes a filter element having an inner wall and at least one filter opening for passage of the wash fluid. The filter opening is bounded by the inner wall running around the filter opening. The inner wall has an upstream wall segment and a downstream wall segment, with a gradation being formed at least in a segment between an upstream and downstream wall segment of the inner wall of the filter opening. Additionally or independently hereof, the downstream wall segment has a cross section that increases in a flow direction of the wash fluid.