Ice Maker Sump Pressure Sensing for Accurate Ice Thickness
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Solution Overview
Problem
Existing ice makers face challenges in accurately determining ice thickness for harvesting, as sensors are often located in the food zone, prone to contamination, require precise mechanical adjustment, and can fail due to mechanical parts or misplacement, leading to issues with water leakage detection and incorrect ice formation.
Innovation Solution
A system utilizing a piezoresistive transducer and microcontroller to detect water level changes in the sump, allowing for electronic adjustment and avoiding contamination, with a pressure sensor submerged in the sump to monitor water level variations and initiate the harvest cycle, while also detecting leaks and controlling fill and purge functions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a hinged sensor is used to directly measure ice thickness, then measurement precision is improved, but reliability deteriorates due to mechanical parts and contamination exposure
Solution Approach 1:
The patent replaces the mechanical hinged sensor with an optical measurement system using a transparent indicator and light source. This substitution eliminates mechanical moving parts that could fail, while maintaining the ability to directly measure ice thickness. The optical system is less susceptible to contamination and mechanical failure, thereby improving reliability while preserving measurement precision.
Solution Approach 2:
The patent introduces a transparent indicator as an intermediary element between the ice and the light source. This indicator moves with the ice growth and provides a visual reference point for measuring ice thickness. The intermediary allows indirect optical measurement without requiring direct contact between the sensor and ice, reducing contamination risks while maintaining measurement accuracy.
2Measurement precision
If the sensor is placed in the food zone for direct measurement, then measurement precision is improved, but object-affected harmful factors worsen due to contamination and NSF compliance requirements
Solution Approach 1:
The transparent indicator serves as an intermediary that can be placed in the food zone without requiring the sensor itself to be in direct contact with water or ice. The light source and detection system remain outside the food zone, eliminating contamination risks while allowing the indicator to directly measure ice thickness in the food zone environment.
Solution Approach 2:
By replacing the mechanical sensor with an optical system using transparent indicators, the patent eliminates the need for NSF-compliant food-grade sensor materials and geometries. The optical components can be positioned outside the food zone while still achieving direct measurement through the transparent indicator, thereby avoiding contamination issues and regulatory compliance requirements.
3Ease of manufacture
If mechanical adjustment is used for sensor positioning, then ease of manufacture is improved, but manufacturing precision deteriorates due to manual adjustment errors
Solution Approach 1:
The patent replaces mechanical sensor positioning with an optical system using transparent indicators that naturally align with ice growth. This eliminates the need for precise mechanical adjustment of sensor position, as the indicator automatically positions itself relative to the ice surface. The system maintains ease of manufacture while achieving consistent, accurate positioning without manual adjustment errors.
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 solution provides accurate and electronic control of ice thickness measurement, prevents sensor contamination, and safeguards against water leakage, ensuring proper ice formation and machine operation, reducing the risk of malformed ice and machine failure.
Implementation Method 1
A system utilizing a piezoresistive transducer and microcontroller to detect water level changes in the sump
Implementation Method 2
a pressure sensor submerged in the sump to monitor water level variations
Implementation Method 3
Water cascades down the freeze plate... gradually frozen into ice cubes
Implementation Method 4
the refrigeration cycle is reversed and the freeze plate is heated to melt the formed ice cubes away
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A method of controlling an ice maker having the steps of filling a sump of the ice maker with water, cascading the water across a freeze plate to make ice cubes, during an estimated sensible cooling time period for the water, sensing whether the water level in the sump has decreased, and indicating that a malfunction exists in the ice maker if during the sensible cooling time period the water level within the sump is sensed to have changed more than a predetermined amount.