Control systems and methods for cooktop appliances
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Solution Overview
Problem
Existing gas cooktop appliances face challenges with long-term drift and limited accuracy in temperature control, especially at low flow rates, and are often expensive, requiring precise metering devices, which limits their applicability.
Innovation Solution
A cooktop appliance with a gas burner system that includes a manifold, primary and secondary gas flow lines, a flow control valve, and a control system with sensors and controllers to regulate temperature, allowing for automatic mode operation that maintains precise temperature control by modulating gas flow between on and off states to achieve an average operational BTU output below the minimum operational BTU output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If precision flow control valves and precise metering devices are used for temperature control, then temperature control accuracy is improved, but device cost and complexity increase
Solution Approach 1:
The gas flow control system is segmented into two independent pathways: a modulated gas line with a flow control valve for precise temperature regulation, and a non-modulated minimum gas flow line that maintains a constant baseline flow. This segmentation allows the system to achieve precise temperature control without requiring the entire gas flow system to be highly complex, as only the modulated line requires precision components.
Solution Approach 2:
The non-modulated minimum gas flow line acts as an intermediary element that provides a stable baseline gas flow to the burner. This intermediary pathway eliminates the need for the main gas control system to handle extremely low flow rates directly, thereby reducing the complexity and cost requirements for precision metering devices while maintaining temperature control accuracy.
2Measurement precision
If precision flow control valves are used for temperature regulation, then temperature control accuracy is improved, but long term drift occurs
Solution Approach 1:
By separating the gas flow control into modulated and non-modulated lines, the system isolates the precision requirements to only the modulated line while the non-modulated line provides a stable reference. This segmentation reduces the cumulative drift effects that would occur if a single precision valve had to maintain both baseline and variable flow control over long periods.
Solution Approach 2:
The system periodically adjusts the flow control valve to maintain accurate temperature control, allowing for calibration and recovery from drift. The dual-line design enables the system to discard accumulated errors in the modulated line by resetting the flow control valve position based on current temperature feedback, while the non-modulated line continues to provide stable baseline flow.
3Measurement precision
If precise metering devices are used for gas flow control, then temperature control accuracy is improved, but device cost increases
Solution Approach 1:
The gas control system is divided into two lines with different precision requirements. The non-modulated minimum gas flow line uses simpler, less expensive components since it only needs to maintain a constant flow. The modulated gas line uses precision flow control components only where needed for temperature regulation. This segmentation reduces overall manufacturing costs compared to requiring precision metering devices throughout the entire gas flow system.
Solution Approach 2:
The system uses a relatively simple flow control valve in the modulated line rather than expensive precision metering devices, accepting that the valve may require periodic adjustment or replacement. This approach trades long-term component replacement for lower initial manufacturing costs and reduced system complexity.
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 precise temperature control without long-term drift and at a lower cost, enabling efficient cooking operations, including sous vide cooking, by using a control system that adjusts gas flow to maintain desired temperatures within a narrow tolerance, reducing the need for expensive metering devices and improving general applicability.
Implementation Method 1
a flow control valve disposed along the secondary line and modulated in response to the actual temperature to maintain the temperature at the cooking hardware at the desired temperature
Implementation Method 2
a sensor disposed at the cooking hardware and configured to sense an actual temperature
Implementation Method 3
a controller modulating gas flow to the gas burner between an on-state and an off-state to maintain the average operational BTU output below the minimum operational BTU output of the gas burner
Implementation Method 4
a gas burner; a manifold having a gas input; a primary line extending between the manifold and the gas burner
Data Source
AI summary
Cooktop appliances are provided. A cooktop appliance can include a gas burner; a manifold having a gas input; a primary line extending between the manifold and the gas burner, wherein the primary line operates as a non-modulated minimum gas flow line when the cooktop appliance is in an automatic mode; a secondary line extending between the manifold and the gas burner, wherein a gas flow rate of the secondary line is controllable by a flow control valve; a primary valve in fluid communication with at least the primary line; and a control system including: a sensor configured to detect a temperature corresponding to the gas burner; and a controller regulating: (i) the flow control valve in response to the detected temperature to achieve a desired temperature, and (ii) the primary valve when the flow control valve is closed and the detected temperature exceeds the desired temperature.