Variable Orifice Gas Flow Modulating Valve for Stable Combustion
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Solution Overview
Problem
Existing gas valves for appliances suffer from fluctuations in output due to on/off cycling, leading to undesirable temperature variations and inefficient combustion, with previous solutions like solenoid-operated valves experiencing hysteresis and non-repeatability issues, and metering pin designs resulting in non-circular gas jets that hinder optimal combustion.
Innovation Solution
A variable orifice gas flow modulating valve featuring a metering pin with a cylindrical sidewall, tapered frustoconical head, and fins, coupled with an actuator, which allows for precise control of gas flow through a tapered orifice hood, maintaining constant pressure and velocity for improved combustion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If pressure regulation is used to modulate gas flow, then gas flow control is achieved, but pressure drop ahead of the orifice reduces gas velocity and primary air intake
Solution Approach 1:
The invention extracts the metering function from the pressure regulation mechanism. Instead of using pressure drop to control flow, a separate metering pin with precision bore directly meters the gas volume at constant pressure, eliminating the harmful pressure drop while maintaining flow control capability
Solution Approach 2:
The gas flow control system is segmented into two independent functions: pressure regulation (maintaining constant pressure) and flow metering (controlling volume via metering pin). This separation allows each function to operate optimally without compromising the other
2Ease of operation
If a solid metering pin is used in the outlet orifice, then gas flow modulation is achieved, but a non-circular gas jet is produced that hinders optimal combustion
Solution Approach 1:
The metering pin features a precision bore with specific geometric characteristics (circular cross-section, controlled length-to-diameter ratio) that ensure the gas jet maintains a circular profile. This local geometric quality at the metering point directly enables optimal combustion by providing the correct jet shape
3Extent of automation
If solenoid operated valves are used for gas flow control, then automated modulation is achieved, but hysteresis and non-repeatability issues occur
Solution Approach 1:
The invention replaces the solenoid-operated mechanical valve system with a constant pressure valve combined with a metering pin system. This substitution eliminates the hysteresis and non-repeatability inherent in solenoid mechanisms while maintaining automated control capability through the metering mechanism
4Device complexity
If a traditional on/off gas valve is used, then simple two-position control is achieved, but undesirable fluctuations in appliance output occur
Solution Approach 1:
The invention transitions from static on/off valve positions to a dynamic metering system where the metering pin can be positioned at multiple intermediate locations. This enables continuous gas flow modulation, allowing the appliance to maintain stable temperature without the fluctuations caused by cycling on/off control
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 solution provides stable temperature control and enhanced combustion efficiency by maintaining constant gas flow pressure and velocity, reducing fluctuations and hysteresis, and ensuring a centered, circular gas jet for complete combustion.
Implementation Method 1
maintaining constant pressure and velocity for improved combustion
Implementation Method 2
variable orifice gas flow modulating valve
Implementation Method 3
coupled with an actuator, which allows for precise control of gas flow
Implementation Method 4
ensuring a centered, circular gas jet for complete combustion
Data Source
AI summary
A temperature control system for a gas appliance utilizes an improved variable orifice gas flow modulating valve capable of direct modulation of gas flow through an orifice directly into a gas burner to provide a constantly maintained temperature in an appliance working compartment, as selected by human interface via a temperature selector. An actuator attached to a gas fitting body of the valve provides for linear movement of a metering pin into the taper inside the orifice, accomplishing the variable controlled modulated flow of gas directly into the burner. The actuator is controlled by an input signal from a programmable controller whose output is determined by calculations based on inputs from a temperature selector and a temperature sensor located in the gas appliance working compartment.