Washing Machine Dry Load Weight Detection Using Motor Power Drop
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Solution Overview
Problem
Conventional methods for determining dry load weight in washing machines are complex, time-consuming, and inaccurate, requiring costly sensors, which compromises wash performance and consumer satisfaction.
Innovation Solution
A washing machine system that determines dry load weight by accelerating a wash basket to a predetermined speed, measuring the power drop between acceleration and steady-state motor power, and using this power difference to calculate the dry load weight without complex sensors or algorithms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional sensors and algorithms are used to detect dry load weight, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces complex mechanical sensing systems with a simplified electrical measurement approach. Instead of using multiple sensors and complex algorithms, the system measures motor current draw during a spin cycle and uses this electrical parameter to infer load weight, thereby reducing device complexity while maintaining measurement capability
Solution Approach 2:
The system uses the motor's own operational characteristics (current draw during spinning) to provide load weight information. The motor essentially serves dual purposes: both driving the wash basket and providing the measurement signal, eliminating the need for separate sensing systems
2Measurement precision
If conventional sensors and algorithms are used to detect dry load weight, then measurement precision is improved, but manufacturing cost increases
Solution Approach 1:
The patent employs inexpensive measurement approaches using standard motor current sensing capabilities that are already present in most washing machines. By utilizing existing components for dual purposes (motor operation and load sensing), the system avoids expensive specialized sensors while achieving functional equivalence
Solution Approach 2:
The motor serving dual functions (driving the basket and providing load measurement through current draw analysis) exemplifies multi-functionality. This universal approach allows a single component to fulfill multiple roles, reducing overall system cost while maintaining measurement precision
3Measurement precision
If conventional dry load weight detection methods are used, then measurement precision is improved, but loss of time increases
Solution Approach 1:
The system performs load weight measurement continuously during the spin cycle operation. Rather than requiring a separate measurement phase, the useful action of spinning the basket simultaneously provides both the operational function and the measurement opportunity, eliminating time loss while maintaining accuracy
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 method provides accurate and efficient dry load weight detection, optimizing wash parameters and improving wash performance without the need for costly sensors, leading to enhanced consumer satisfaction.
Implementation Method 1
determining a dry load weight based on a power drop between the acceleration power and the steady state power
Data Source
AI summary
A washing machine appliance includes a wash tub defining a wash chamber, a wash basket rotatably mounted within the wash tub, and a motor operably coupled to the wash basket for selectively rotating the wash basket. A controller is configured for accelerating the wash basket to a predetermined speed during an acceleration period and maintaining that speed during a steady state period. The controller further determines a power drop from the maximum power required to accelerate the wash basket to the power required to maintain the predetermined speed, and the dry load weight is calculated using this power drop and a transfer function.