Staged oven self-clean preheat temperature control

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Manufacturing variations in cooking elements can cause cooking appliances with similar construction and control to fail time-temperature curve comparisons, necessitating full testing for certification, even if they are substantially similar to existing certified products.

Innovation Solution

A cooking appliance with a controller that regulates electric cooking elements to maintain an intermediate temperature setpoint during the preheat phase of the self-clean cycle, pausing temperature rise until predetermined times are reached, thereby controlling the time-temperature curve and reducing variance due to manufacturing variations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If cooking appliances are manufactured with standard tolerances for cooking elements, then manufacturing cost and ease of production are improved, but time-temperature curve consistency deteriorates causing certification failures

Engineering Contradiction:

Improvemanufacturing easeVSAvoidtime-temperature curve consistency

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The controller continuously monitors the actual temperature within the oven cavity during the preheat phase and compares it to the target temperature. Based on this feedback, the controller dynamically adjusts the power delivered to cooking elements, compensating for manufacturing variations in element output power. This closed-loop control ensures that appliances with different cooking element specifications all achieve the same time-temperature curve, resolving the contradiction between manufacturing ease and time-temperature curve consistency.

Inventive Principle:

Principle #23Feedback

2Duration of action of moving object

If the oven preheats directly to self-clean temperature, then the self-clean cycle duration is reduced, but the time-temperature curve becomes sensitive to cooking element variations causing certification issues

Engineering Contradiction:

Improveself-clean cycle durationVSAvoidtime-temperature curve consistency

Core Design Contradiction:

Duration of action of moving objectVSManufacturing precision

Solution Approach 1:

The preheat phase is divided into multiple temperature stages: an initial stage heating to an intermediate temperature (e.g., 200°C), followed by a pause period, then a second stage heating to the final self-clean temperature. This segmentation allows the controller to manage the complex heating process in manageable steps, ensuring that the cumulative time to reach self-clean temperature remains consistent across different appliances while accommodating manufacturing variations in cooking element power.

Inventive Principle:

Principle #1Segmentation

3Adaptability or versatility

If cooking element output power varies due to manufacturing tolerances, then production flexibility is improved, but the rise time to self-clean temperature becomes inconsistent

Engineering Contradiction:

Improveproduction flexibilityVSAvoidrise time consistency

Core Design Contradiction:

Adaptability or versatilityVSLoss of time

Solution Approach 1:

The controller uses real-time temperature feedback to compensate for variations in cooking element output power. By continuously monitoring the heating rate and adjusting power delivery accordingly, the system ensures that the rise time to self-clean temperature remains consistent regardless of manufacturing tolerances in cooking element specifications. This maintains production flexibility while achieving time consistency.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The controller pre-calculates and stores pause durations at intermediate temperature stages based on expected cooking element performance ranges. When an appliance begins operation, the controller applies these pre-determined pause times to compensate for manufacturing variations, ensuring consistent rise time without requiring real-time complex calculations. This preliminary preparation enables the system to handle production flexibility while maintaining time consistency.

Inventive Principle:

Principle #10Preliminary action

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 provides a consistent time-temperature curve that is more resistant to manufacturing variations, potentially allowing for test waivers and reducing certification testing requirements by controlling the rise time to the self-clean temperature setpoint independently of cooking element output power.

Implementation Method 1

a temperature sensor configured to sense an air temperature within the oven cavity

Methodology Applied

Scientific EffectTemperature sensing: Thermal Radiation

Implementation Method 2

one or more electric cooking elements configured to generate heat within the oven cavity

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Data Source

PatentUS11009238B2Staged oven self-clean preheat temperature control

Publication Date: 2021.05.18 MIDEA GROUP CO LTD

AI summary

One or more cooking elements of a cooking appliance may be controlled during the preheat phase of an oven self-clean cycle to maintain a temperature within an oven cavity proximate an intermediate temperature setpoint that is below a self-clean temperature setpoint for the oven self-clean cycle until reaching a predetermined time in the oven self-clean cycle.