Washing Machine Laundry Load Estimation Using Motor Torque Integration
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Solution Overview
Problem
Existing methods for determining the laundry load in washing machines are either time-consuming, inaccurate, or limited to specific fabric types, and require complex algorithms or user input errors.
Innovation Solution
A method involving controlling the laundry drum's rotational speed according to a prefixed reference speed profile, sampling torque values during acceleration and constant speed phases, and calculating an integral value to determine the laundry load, which is then used to estimate the load index and amount.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If water absorption method is used to estimate laundry load, then the estimation can be performed without additional electrical components, but the estimation time becomes very long (several minutes) and accuracy is low due to fabric-dependent water absorption
Solution Approach 1:
The patent replaces the water absorption method (which relies on fabric-dependent water uptake) with an electrical measurement method using motor current. The motor's electrical characteristics during drum rotation provide direct information about laundry load mass, enabling quick and accurate measurement independent of fabric type.
Solution Approach 2:
The patent changes the measurement parameter from water absorption (which varies with fabric) to motor current consumption (which directly correlates with mechanical load). By measuring electrical parameters during controlled drum rotation, the system achieves fast and accurate load detection without the time-consuming water absorption process.
2Device complexity
If water absorption method is used, then no additional electrical components are needed, but the accuracy strongly depends on fabric type and requires complex correction algorithms
Solution Approach 1:
The patent replaces the complex water absorption measurement system with a simpler electrical measurement approach. By using the motor's existing electrical components to measure current during rotation, the system eliminates the need for water loading infrastructure and complex fabric-type correction algorithms.
Solution Approach 2:
The patent makes the motor serve dual purposes: both driving the drum and providing load measurement data through its electrical characteristics. The motor's current consumption during controlled rotation automatically provides load information without requiring separate measurement systems or correction algorithms for different fabric types.
3Loss of time
If motor power method is used to determine laundry load, then the measurement can be performed quickly, but additional electrical components and complex algorithms are required
Solution Approach 1:
The patent makes the motor serve dual purposes: both driving the drum and providing load measurement data through its electrical characteristics. The motor's current consumption during controlled rotation automatically provides load information without requiring separate measurement systems or correction algorithms for different fabric types.
Solution Approach 2:
The patent makes the motor serve dual purposes: both driving the drum and providing load measurement data through its electrical characteristics. The motor's current consumption during controlled rotation automatically provides load information without requiring separate measurement systems or correction algorithms for different fabric types.
4Measurement precision
If integrated torque measurement is used, then quick and accurate load determination is achieved, but the control system becomes more complex
Solution Approach 1:
The patent makes the motor serve dual purposes: both driving the drum and providing load measurement data through its electrical characteristics. The motor's current consumption during controlled rotation automatically provides load information without requiring separate measurement systems or correction algorithms for different fabric types.
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 allows for quick, precise, and accurate determination of the laundry load without additional electrical components, improving upon existing methods by reducing estimation time and enhancing accuracy across various fabric types.
Implementation Method 1
an electric motor for rotating said drum... sampling first torque values generated by said electric motor during said acceleration ramp... sampling second torque values generated by said motor during said constant speed phase
Data Source
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AI summary
The present invention relates to a method to control a laundry treatment machine (1) comprising an outer casing (2), a washing group which is placed inside the outer casing (2) and comprises, in turn, a rotatable drum (6) structured for housing the laundry to be treated, an electric motor (16) for rotating the drum (6); the method comprises: controlling the electric motor (16) to cause the drum (6) to change its rotational speed according to a prefixed reference speed profile comprising at least an acceleration ramp (Ra(i)), wherein the drum (6) is accelerated from a low speed (B1) to a prefixed high speed (B2) and at least a constant speed phase (S(k)) wherein the drum speed is maintained about the high speed (B2), sampling first torque values (Ti) generated by the electric motor (16) during the acceleration ramp (Ra(i)) according to a prefixed first sample time (Δta), sampling second torque values (Tj) generated by the electric motor (16) during the constant speed phase (S(k)) according to a prefixed second sample time (Δtb), calculating a third value (TU), which is indicative of an average torque value based on said second torque values (Tj), determining a fourth value by performing an approximate integral calculus consisting of subtracting said third value (TU) from said first torque values (Ti), and determining the amount of laundry load (QL) on the basis of said fourth torque value (Torque_int).