Dishwasher Cap Design to Prevent Backward Flow Contamination
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Solution Overview
Problem
Conventional dishwashers experience a backward flow phenomenon where wash water from the filter unit flows back into the washing tub, potentially reintroducing filtered contaminants, which contaminates the wash water and affects cleaning efficiency.
Innovation Solution
A dishwasher design featuring a cap within the filter unit that moves upward and downward with water flow to open and close a flow channel, preventing backward flow from the filter unit to the washing tub, utilizing a mesh structure and hooks to restrict movement and maintain separation between the sump and washing tub.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a filter unit is installed in the sump to filter foreign matter from wash water, then filtering effectiveness is improved, but wash water may flow backward from the filter unit to the washing tub causing contamination
Solution Approach 1:
The cap is designed to move dynamically between a lowered position (allowing wash water flow) and a raised position (blocking backward flow). This dynamic positioning resolves the contradiction by adapting the flow control mechanism to different operational states: during normal washing, the cap remains lowered to allow filtered water passage; during pump shutdown, the cap rises to prevent backward flow and contamination
Solution Approach 2:
The cap acts as an intermediary element between the filter unit and the washing tub. It mediates the water flow between these two components, allowing forward flow while blocking backward flow. The cap's selective blocking function prevents contaminants from re-entering the washing tub while maintaining the filtering function of the filter unit
2Reliability
If the cap is allowed to move freely with water flow to control backward flow, then backward flow prevention is improved, but the cap may be displaced beyond functional limits
Solution Approach 1:
The hooks are pre-positioned on the filter unit to engage with the cap at specific positions. The first hook is preliminarily positioned to engage the cap when it rises to prevent over-displacement during backward flow prevention. The second hook is preliminarily positioned to engage the cap and form discharge ports during normal operation. These pre-positioned engagement points ensure the cap remains within functional limits
Solution Approach 2:
The hooks provide protective engagement points that cushion the cap's movement before it can be displaced beyond functional limits. When backward flow occurs and the cap rises, the first hook engages to prevent excessive upward displacement that would compromise the system. This beforehand cushioning protects the cap-positioning system from potential damage or malfunction
3Stability of the object's composition
If the cap is restricted from moving upward to prevent over-displacement, then position stability is improved, but backward flow prevention capability is reduced
Solution Approach 1:
The dual-hook system creates a dynamic positioning mechanism where the cap can engage different hooks based on operational conditions. During normal operation, the second hook engages to maintain stability. During backward flow events, the cap can rise to engage the first hook, which provides upward restriction. This dynamic engagement allows the system to maintain stability during normal operation while enabling backward flow prevention when needed
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
Effectively prevents wash water from flowing backward into the washing tub, thereby preventing contamination and maintaining cleanliness during the washing cycle without requiring additional power sources, while maintaining the conventional sump structure.
Implementation Method 1
The cap is moved upward and downward by a stream of water
Data Source
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AI summary
A dishwasher is disclosed. The dishwasher includes a washing tub (4) defining a space in which dishes are washed by wash water, a sump (40) for collecting wash water introduced from the washing tub, a filter unit (100) disposed at the sump for filtering foreign matter from wash water flowing from the washing tub to the sump, and a cap (50) for preventing wash water from flowing backward from the filter unit (100) to the washing tub (4).