Gas Water Heater Igniter Controller Voltage Adaptation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing controllers for gas-fired water heaters, particularly those using silicon nitride hot surface igniters, face challenges in maintaining the igniter temperature within the critical range to prevent premature failure, as they need to control power to avoid exceeding 1350°C, and must be configured for specific voltage levels (120V or 240V) to ensure proper igniter operation.
Innovation Solution
A controller with a processor that determines the voltage level and selects an appropriate switching sequence from a look-up table to maintain an average voltage of 98-102V to the igniter, using voltage sensing means and comparator circuits to ensure the igniter operates within the desired temperature range, regardless of the input voltage level.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the igniter temperature is increased to ensure sufficient ignition, then the ignition reliability is improved, but the igniter temperature exceeds the critical 1350°C limit causing premature failure
Solution Approach 1:
The controller applies power to the igniter in periodic pulses rather than continuously. The duty cycle is adjusted based on the detected line voltage level, providing sufficient thermal energy for reliable ignition while allowing cooling periods that prevent the igniter from exceeding the critical 1350°C temperature limit.
Solution Approach 2:
The controller dynamically changes the duty cycle parameter based on the detected line voltage level. When line voltage is high, the duty cycle is reduced to limit igniter temperature. When line voltage is low, the duty cycle is increased to ensure sufficient ignition energy. This adaptive parameter adjustment resolves the contradiction between achieving reliable ignition and preventing overheating.
2Manufacturing precision
If the controller is designed for a specific voltage level (120V or 240V), then the control precision for igniter temperature is improved, but the adaptability to different voltage sources deteriorates
Solution Approach 1:
The controller is designed with voltage detection capability that automatically identifies whether the connected power source is 120V or 240V. Based on the detected voltage level, the controller selects appropriate duty cycle values from stored tables to maintain precise igniter temperature control. This multi-functionality allows the same controller hardware to adapt to different voltage sources while maintaining control precision.
Solution Approach 2:
The controller pre-stores multiple duty cycle tables corresponding to different line voltage levels (120V and 240V) and various igniter types. Upon startup, the controller detects the line voltage level and selects the appropriate pre-calculated duty cycle table, eliminating the need for manual configuration and ensuring optimal temperature control from the beginning of operation.
3Temperature
If the duty cycle is increased to compensate for low line voltage, then the igniter temperature is sufficient for ignition, but the igniter temperature may exceed the critical limit causing premature failure
Solution Approach 1:
The controller incorporates feedback through the detection of actual line voltage levels and adjusts the duty cycle accordingly. By continuously monitoring the voltage input and comparing it against expected values, the controller calculates the appropriate duty cycle to achieve the target igniter temperature without exceeding the 1350°C limit, thereby maintaining both ignition sufficiency and igniter reliability.
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
The controller effectively maintains the igniter temperature between 1150°C and 1350°C, preventing premature failure while accommodating either 120V or 240V power sources, ensuring reliable operation and extending the lifespan of the silicon nitride igniter.
Implementation Method 1
a voltage sensing means for sensing the voltage value of the electrical power source
Implementation Method 2
a switching means for connecting an electrical power source to an igniter for igniting gas
Data Source
AI summary
A controller is provided for controlling the operation of a gas-fired water heating appliance. In one embodiment of the present invention, a controller is provided that comprises a switching means for connecting an electrical power source to an igniter for igniting gas, a voltage sensing means for sensing the voltage value of the electrical power source, and a processor that is capable of determining whether the power source is of a first rated voltage level or a second rated voltage level. The processor is capable of responsively selecting an appropriate switching sequence from a look-up table having a plurality of switching sequences corresponding to a plurality of voltage values for either the first rated voltage or the second rated voltage, where the processor controls the switching means based on the selected switching sequence to effect switching of power to supply an average predetermined voltage to the igniter that will heat the igniter to a desired temperature.