Toilet Trapway Heel Geometry for Low-Volume Siphon Formation
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Solution Overview
Problem
Conventional toilets with low water usage per flush cycle face challenges in achieving effective bowl cleaning due to the difficulty in forming a siphon in the trapway, which requires significant water and can lead to clogging issues, especially when trying to reduce water usage below 1.6 gallons per flush.
Innovation Solution
The trapway design features a heel geometry with varying cross-sectional dimensions that focuses the water flow, facilitating rapid siphon formation and maintenance, even with low water volumes, by transitioning from a down leg to an out leg with a bend that increases the major dimension and reduces the minor dimension, thereby optimizing water utilization and preventing clogs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If conventional trapway designs are used with low water usage (1.6 gallons or less), then water conservation is achieved, but bowl cleaning effectiveness deteriorates due to difficulty in forming a siphon
Solution Approach 1:
The trapway incorporates a heel section with non-uniform cross-sectional dimensions where the major dimension increases and the minor dimension decreases, creating a localized flow-focusing region. This local geometric modification concentrates the limited water flow into a coherent stream that effectively initiates and maintains siphon action, resolving the contradiction between low water usage and effective bowl cleaning.
2Loss of substance
If water flow is reduced to below 1.6 gallons per flush, then water conservation is improved, but the time required to form a siphon increases
Solution Approach 1:
The heel geometry is pre-configured with specific dimensional variations that anticipate and prepare the water flow for siphon formation. The increasing major dimension and decreasing minor dimension create a predetermined flow path that naturally focuses and accelerates the water, enabling rapid siphon initiation even with reduced water volumes, thus reducing siphon formation time.
3Speed
If water flow is concentrated to form a siphon quickly, then siphon formation speed is improved, but clogging risk increases
Solution Approach 1:
The trapway design incorporates dynamic geometric transitions in the heel section where cross-sectional dimensions vary along the flow path. The major dimension increases then decreases, while the minor dimension decreases then increases, creating a dynamic flow-focusing effect that maintains high siphon formation speed while preventing flow stagnation and reducing clogging risk through continuous flow motion.
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 design enables efficient and reliable bowl evacuation with reduced water waste, ensuring effective cleaning even with minimal water usage, while maintaining a consistent siphon throughout the flush cycle and minimizing the risk of clogging.
Implementation Method 1
A down leg of the trapway which is downstream of the weir is a leg that is designed to develop a siphon once the flushing cycle starts, to help further evacuate the bowl
Data Source
AI summary
A toilet has a trapway extending between a bowl opening and a toilet outlet opening. A heel links and provides a bend between a down leg and an out leg of the trapway. The heel has a cross-sectional profile having a major dimension and a minor dimension. The major dimension increases as the down leg transitions into the heel and reduces as the heel transitions into the out leg. This heel configuration in the trapway forms a siphon during a flushing action of the toilet.