Laundry Dryer Fan Speed Control for Variable Drum Loads
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Solution Overview
Problem
Laundry dryers often operate suboptimally when the load inside the drum is less than maximum, leading to inefficient drying cycles due to fixed speed settings that do not adapt to the actual load.
Innovation Solution
A method and system where the speed of the fan motor is adjusted based on the power or current absorbed by the drum motor, increasing speed for partial loads to enhance airflow and reduce drying time, and decreasing speed for higher loads to maintain efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the fan motor speed is set to maximum for all loads, then the drying speed is maximized for full loads, but energy consumption increases and drying quality deteriorates for partial loads
Solution Approach 1:
The fan motor speed is made dynamic rather than fixed, allowing it to adjust according to the actual load conditions in the drum. The control unit varies the fan motor speed based on detected drum motor current, enabling the system to optimize drying performance for each specific load size rather than operating at constant maximum speed.
Solution Approach 2:
The system changes the operational parameters (fan motor speed) based on the load conditions. By detecting the current absorbed by the drum motor and using this information to adjust the fan motor speed, the system adapts its parameters to match the actual drying requirements, avoiding unnecessary energy consumption at maximum speed for partial loads.
2Productivity
If the fan motor speed is set to maximum for all loads, then the drying speed is maximized, but the drying cycle time increases for partial loads due to excessive airflow
Solution Approach 1:
The fan motor speed is dynamically adjusted to match the load conditions. For partial loads, the reduced fan motor speed creates optimal airflow that prevents excessive drying time, while for full loads, the maximum speed maintains high productivity. This dynamic adaptation resolves the contradiction between drying speed and cycle time.
Solution Approach 2:
The control unit uses feedback from the drum motor current detection to adjust the fan motor speed. This closed-loop control ensures that the airflow is optimized based on actual load conditions, preventing both under-drying and over-drying scenarios that would extend the cycle time unnecessarily.
3Loss of time
If the fan motor speed is increased for partial loads, then the airflow is optimized and drying time is reduced, but the system complexity increases
Solution Approach 1:
The control unit performs multiple functions: it controls the drum motor, detects the drum motor current, determines load conditions, and controls the fan motor speed. By making the control unit multi-functional, the system avoids adding separate dedicated components for each function, thereby minimizing the increase in overall system complexity while achieving optimized drying performance.
Solution Approach 2:
The system uses the existing drum motor current detection capability to infer load conditions and automatically adjust the fan motor speed without requiring separate sensors or complex measurement systems. This self-service approach allows the system to adapt to partial loads using already-available information, reducing the complexity burden.
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 adaptation results in improved drying efficiency by optimizing airflow for varying loads, reducing drying time, and enhancing the performance of heat pump systems by improving heat exchange efficiency.
Implementation Method 1
detecting a power or a current absorbed by the drum motor
Implementation Method 2
a drying air stream fan (18) with a variable speed... controlling the speed of the fan motor... optimizing airflow for varying loads
Implementation Method 3
enhancing the performance of heat pump systems by improving heat exchange efficiency
Data Source
AI summary
The present invention relates to a method for controlling a laundry dryer including a fan motor (26) for driving a drying air stream fan (18) with a variable speed (vf) and a drum motor (28) for driving a laundry drum (12), said method comprising the steps of setting a predetermined course for the speed (vd) of the drum motor (28), maintaining the speed (vd) of the drum motor (28) according to the predetermined course for the speed (vd) of said drum motor (28), detecting a power (Pd) or a current absorbed by the drum motor (28), and controlling the speed (vf) of the fan motor (26) on the basis of the absorbed power (Pd) or current of the drum motor (28). The speed (vf) of the fan motor (26) increases with a decreasing absorbed power (Pd) or current of the drum motor (28) and/or the speed (vf) of the fan motor (26) decreases with an increasing absorbed power (Pd) or current of the drum motor (28). Further, the present invention relates to a laundry dryer including an air stream circuit with a drying air stream fan and a laundry drum.