Liquid Heater A/F Sensor Drying Control
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Solution Overview
Problem
In liquid heater apparatuses, the controller's inability to determine if the air/fuel (A/F) sensor is completely dry leads to inefficient energy consumption and inconsistent start times due to varying drying times based on water conditions, causing the A/F sensor to be overheated or underutilized.
Innovation Solution
A controller uses a timer and the change in current gradient of the heating portion to determine when the A/F sensor is dry, setting a drying time and heating completing time to efficiently heat the sensor to the target temperature, reducing energy waste by monitoring temperature and resistance changes without an additional thermometer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the A/F sensor is heated for a fixed drying time without determining whether water is completely dried, then the A/F sensor is guaranteed to be dry, but electric energy is over consumed because heating continues beyond the necessary drying time
Solution Approach 1:
The controller monitors the current value of the heating portion in real-time during the drying process. When the current reaches a predetermined threshold indicating complete drying, the controller stops heating. This feedback mechanism eliminates unnecessary continued heating while ensuring the sensor is thoroughly dried, thus resolving the contradiction between reliability and energy consumption.
Solution Approach 2:
The heating portion serves dual purposes: it dries the A/F sensor and simultaneously provides the current signal that indicates drying completion. The system uses its own operational parameter (current) to determine when to stop, eliminating the need for separate monitoring systems and enabling automatic termination of heating at the optimal moment.
2Use of energy by moving object
If the controller determines whether the A/F sensor is completely dried, then electric energy is not over consumed, but the start timing when the A/F sensor could be used is not consistent due to varied drying times
Solution Approach 1:
The heating process transitions from a static fixed-time approach to a dynamic adaptive approach. The controller continuously monitors current values and adjusts the heating duration based on actual drying conditions. This dynamic adjustment allows the system to adapt to varying water conditions while maintaining consistent operational start timing by precisely terminating heating when drying is complete.
Solution Approach 2:
The patent replaces the mechanical timer-based drying control with an electrical parameter-based control system. By using current monitoring instead of time-based control, the system achieves more precise and adaptive drying termination, resolving the inconsistency in start timing while reducing energy consumption.
3Speed
If the A/F sensor is heated suddenly to the target temperature, then the sensor is quickly activated, but the sensor may be damaged when it is wet or iced
Solution Approach 1:
The controller implements a two-stage heating process: first, a drying phase at lower power to evaporate moisture and ice safely; second, a rapid heating phase to reach the target temperature quickly. This preliminary drying action prevents thermal shock and damage to wet or iced sensors while still achieving fast activation afterward.
Solution Approach 2:
The heating process is divided into distinct periodic stages: an initial drying period with monitored current values, followed by a rapid heating period once drying is complete. This periodic structure allows safe moisture removal first, then quick temperature elevation, resolving the contradiction between heating speed and sensor safety.
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 approach ensures the A/F sensor reaches the target temperature within the predetermined time, optimizing energy use and maintaining consistent start times by accurately controlling the heating process based on current and resistance changes.
Implementation Method 1
When the water covering the A/F sensor is evaporated, both the temperature of the heater portion and the resistance value of the heater portion are increased simultaneously
Implementation Method 2
the controller so controls the heating portion heats the A/F sensor that the temperature of the A/F sensor reaches the target temperature
Implementation Method 3
When the water covering the A/F sensor is evaporated, both the temperature of the heater portion and the resistance value of the heater portion are increased simultaneously, so that the current of the heater portion is decreased
Data Source
AI summary
A liquid heater apparatus increases the temperature of an A/F sensor up to a target temperature by a target heating time. The liquid heating apparatus such as a gas water heater uses the A/F sensor for detecting an oxygen density in a heating tube. An MPU of a controller count a time from beginning by using a timer and decides whether a moisture on the A/F sensor is evaporated by using the change of a current for a heater portion of the A/F sensor. When the MPU decides the A/F sensor is dried out, the MPU counts the time from the beginning to such time tα as a drying time and setts a heating completing time by reducing the drying time from the predetermined target time. The MPU so controls the heating portion that the temperature of the sensor portion becomes the target temperature by the heating completing time.