Dual-Processor Ignition Control for Gas Appliance Flame Failure Safety
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Solution Overview
Problem
Conventional ignition control systems for gas appliances with direct spark ignition lack reliability in terminating gas flow when ignition fails, leading to potential gas buildup and safety hazards due to the reliance on a single microprocessor and timer circuit.
Innovation Solution
The implementation of a dual-processor ignition control system, comprising a primary processor to initiate and monitor the ignition process and a secondary processor to independently terminate the gas flow if the primary processor fails to do so, ensuring safe shutdown and preventing uncontrolled gas release.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single microprocessor and timer circuit are used to control ignition, then the device complexity is reduced, but the reliability of terminating gas flow upon ignition failure deteriorates
Solution Approach 1:
The control system is segmented into two independent microprocessors: a primary microprocessor that executes the ignition sequence and a secondary microprocessor that independently monitors the ignition process. Each processor has separate memory and processing capabilities, allowing them to operate independently to verify ignition status and control gas valve termination, thereby eliminating single-point failures.
Solution Approach 2:
The secondary microprocessor is pre-programmed with the same ignition timing parameters and monitoring logic as the primary processor. This redundant monitoring capability is established before ignition failure can occur, providing a safety cushion that ensures gas flow termination even if the primary processor fails to detect ignition failure.
2Reliability
If a dual-processor system is implemented to monitor ignition, then the reliability of gas flow termination is improved, but the device complexity increases
Solution Approach 1:
Both microprocessors are integrated into a single control board and share common hardware resources including the gas valve control circuit, flame detection input, and power supply. The processors communicate through shared memory locations and use the same physical I/O ports, reducing overall system complexity while maintaining redundant processing capabilities.
Solution Approach 2:
Each microprocessor is designed to perform multiple functions: initiating the ignition sequence, monitoring flame detection signals, controlling gas valve timing, and detecting failures in the other processor. This multi-functionality reduces the need for additional dedicated components and simplifies the overall system architecture.
Data Source
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AI summary
An ignition control and method are provided for overseeing an ignition process on a fuel-fired appliance having a fuel burner, a fuel flow control valve, an ignition source, and a flame detection device. A primary processor initiates the ignition process, monitors the flame status signal and terminates the ignition process in the presence of a flame status signal indicating no flame after a specified period of time following the initiation of the ignition process. A secondary processor monitors the flame status signal independently of the primary processor and terminates the ignition process in the event that the primary processor fails to terminate the ignition process in the presence of a flame status signal indicating no flame after a specified period of time following the initiation of the ignition process. The primary and secondary processors may each have the functional capability to monitor the operation of the other.