Dryer appliance and method for dryer cycle control
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Solution Overview
Problem
Dryer appliances face inefficiencies in energy consumption and drying performance due to variable ambient temperatures, leading to over-drying or under-drying of laundry loads without software-controlled cycle stages.
Innovation Solution
A method and controller utilizing a voltage divider circuit with thermistors having similar resistance-temperature curves to measure inlet and heated air temperatures, adjusting dryer cycles based on output voltage comparisons to reference voltages, enabling precise control without requiring electronic software.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a temperature setpoint is used without software control, then the dryer can operate with simple hardware, but the dryer cannot adapt to variable ambient temperatures resulting in over-drying or under-drying
Solution Approach 1:
A voltage divider circuit serves as an intermediary between the temperature sensing thermistors and the control relay. The circuit converts temperature differences into voltage signals that the relay can process, enabling adaptive control without complex software while maintaining simple hardware architecture.
Solution Approach 2:
The patent implements feedback by using thermistors to sense inlet and heated air temperatures, converting these signals through a voltage divider circuit, and using the output voltage to control heater pulsing via a relay. This closed-loop feedback system automatically adjusts heating based on actual temperature conditions, enabling adaptation to variable ambient temperatures without software.
2Device complexity
If the dryer operates without adaptive temperature control, then the device complexity is reduced, but energy consumption increases due to over-drying at cold temperatures
Solution Approach 1:
The feedback mechanism using thermistors and voltage divider circuit continuously monitors temperature conditions and adjusts heater operation accordingly. At cold ambient temperatures, the system detects the temperature differential and extends heating duration to reach the required setpoint, preventing under-drying while avoiding unnecessary heating once the target temperature is achieved, thus optimizing energy consumption.
Solution Approach 2:
The control system dynamically adjusts heater pulsing duration and intensity based on real-time temperature feedback. The relay modulates heater operation in response to voltage signals from the thermistors, creating a dynamic control response that adapts to changing ambient conditions and optimizes energy usage throughout the drying cycle.
3Device complexity
If the dryer uses a fixed temperature setpoint, then the control system is simpler, but drying precision deteriorates resulting in over-drying or under-drying
Solution Approach 1:
The voltage divider circuit with thermistors provides continuous feedback on both inlet and heated air temperatures. The control relay uses this feedback to precisely control heater pulsing, maintaining the heated air temperature at the desired setpoint regardless of ambient conditions. This feedback-controlled approach achieves precise drying results without requiring complex software algorithms.
Solution Approach 2:
The patent replaces software-based control with an analog electronic control system using thermistors, voltage divider circuit, and relay. This substitution maintains simplicity while achieving precise temperature control through physical sensing and electronic signal processing, avoiding the need for microprocessors or software algorithms.
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 enhances dryer performance by minimizing over-drying and under-drying, reduces energy consumption, and improves cycle control accuracy, all while eliminating the need for processor-based controllers.
Implementation Method 1
positioning a first thermistor to receive a first temperature signal relative to an inlet flow of air to a heater assembly
Implementation Method 2
positioning a second thermistor to receive a second temperature signal relative to a heated flow of air heated from the heater assembly
Implementation Method 3
determining an output voltage based on an input voltage, the first thermistor, and the second thermistor in a voltage divider circuit
Implementation Method 4
A heater assembly is configured to selectively generate, from an inlet flow of air, a heated flow of air
Data Source
AI summary
A dryer appliance, a controller and a method for dryer cycle control include a voltage divider circuit having a first thermistor configured to receive a first temperature signal corresponding to an inlet flow of air to a heater assembly, and a second thermistor configured to receive a second temperature signal corresponding to a heated flow of air heated from the heater assembly. The first thermistor and the second thermistor have a substantially similar resistance-temperature curve as one another. An output voltage is determined based on an input voltage, the first thermistor, and the second thermistor. A heater control relay is configured to compare the output voltage to a reference voltage corresponding to a control pulsing, a timer adjustment, or a cycle termination. The dryer cycle is adjusted based on the output voltage relative to the reference voltage.