Sensor-less Steady-State Load Temperature Estimation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional heat treatment processes lack an efficient method to determine the steady-state temperature of a load without a load temperature sensor, leading to time delays, increased energy consumption, and higher costs due to reliance on unreliable techniques and manual interventions.
Innovation Solution
A system and method using a controller to estimate the load temperature by fitting control loop signals with an exponential curve, allowing for automatic advancement to the next heat treatment phase when the estimated temperature reaches a user-defined threshold, eliminating the need for a load temperature sensor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a load thermocouple is used to determine steady-state temperature, then measurement accuracy is improved, but device complexity and cost increase due to sensor setup and replacement requirements
Solution Approach 1:
The patent extracts the temperature measurement function from the physical thermocouple sensor and implements it through mathematical estimation using control loop signals. The load temperature is derived by mapping the exponential decay curve of controller signals to temperature values, eliminating the need for physical sensor insertion into the load.
Solution Approach 2:
The patent introduces an intermediary mathematical model (exponential curve fitting and mapping function) that translates controller output signals into estimated load temperature values. This intermediary approach allows temperature estimation without direct thermal contact, avoiding the complexities of physical sensor installation and replacement.
2Device complexity
If conventional indirect techniques or manual operator assessment are used to estimate load temperature, then device complexity is reduced, but measurement precision and reliability deteriorate
Solution Approach 1:
The patent implements a feedback mechanism where the controller continuously monitors its own output signals during the heating phase, fits them to an exponential decay model, and uses this feedback to estimate the load temperature in real-time. This closed-loop approach provides reliable temperature estimation without requiring external sensors or manual intervention.
Solution Approach 2:
The patent replaces the mechanical/physical thermocouple measurement system with a computational approach using control theory and mathematical modeling. The physical sensor-based measurement is substituted with signal processing and curve fitting algorithms that run on the existing controller hardware.
3Reliability
If the heating phase duration is extended to ensure steady-state is reached, then reliability is improved, but productivity and energy efficiency worsen due to time delays
Solution Approach 1:
The patent performs preliminary action by continuously estimating the load temperature during the heating phase using the exponential curve fitting method. This allows the system to proactively identify when steady-state will be reached and prepare for automatic phase transition, rather than waiting for conservative time-based thresholds.
Solution Approach 2:
The patent introduces dynamics to the phase transition decision by using real-time temperature estimation that adapts to actual heating rates. The system dynamically determines the end of heating phase based on the estimated temperature reaching the threshold, allowing faster transitions when heating is efficient and more cautious transitions when heating is slower, optimizing both reliability and productivity.
4Reliability
If conservative time-based thresholds are used to determine phase transition, then reliability is improved, but productivity worsens due to extended heating phases
Solution Approach 1:
The patent changes the parameter used for phase transition determination from a fixed time-based threshold to a dynamic temperature-based threshold. By monitoring the estimated load temperature and comparing it against the steady-state threshold, the system achieves reliable phase transition detection without being constrained by conservative time estimates, thereby reducing unnecessary heating time.
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 reduces energy consumption, increases throughput, and simplifies operations by enabling accurate and automatic identification of the load's steady-state condition, thereby improving overall equipment effectiveness.
Implementation Method 1
The controller fits the collected samples with an exponential curve representing the slowest decay mode of the control loop signal
Data Source
Figure 1
Figure 2(a)~2(f)
Figure 3
AI summary
Estimating the time of reaching steady-state uniform load temperature of a load in a heat treatment process in the absence of a load temperature sensor. In an embodiment, a system utilizes signals and parameters available on a temperature controller to estimate the period of time required for a load to reach a steady-state temperature in a heat treatment process. When the estimate of the temperature of the load reaches the steady-state condition, the system advances the heat treatment process from a load heating phase to another phase.