Washer Drum Coast-Time Load Sensing for Accurate Mass Detection
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Solution Overview
Problem
Existing laundry treating appliances face challenges in accurately determining the load size due to machine variations, temperature fluctuations, motor stall, imbalance effects, and sensing errors, which affect the accuracy of load mass calculation.
Innovation Solution
A method involving a variable speed motor with a controller that determines a first rotational speed, applies a known amount of energy to accelerate the drum, measures the coast time to return to the first speed, and calculates the load size based on the energy and coast time, compensating for machine variations, temperature, and other factors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the drum rotational speed is changed and parameters associated with speed are measured to calculate load mass, then load detection capability is achieved, but measurement precision deteriorates due to machine variations, temperature, friction, motor stall, imbalance effects, power fluctuations, and sensing errors
Solution Approach 1:
The system uses feedback by measuring the actual coast time and comparing it against expected values to determine load mass. The controller continuously monitors the drum's deceleration characteristics and adjusts measurements to compensate for varying conditions, ensuring accurate load detection despite environmental and mechanical variations.
Solution Approach 2:
The invention changes the measurement approach by using coast time (deceleration phase) rather than acceleration parameters. This parameter change allows the system to measure load mass during a controlled deceleration period when the motor is disconnected, eliminating the influence of power fluctuations, motor stall effects, and current sensing errors that plague acceleration-based measurements.
2Measurement precision
If a predetermined amount of energy is applied to accelerate the drum and coast time is measured, then load detection accuracy is improved, but use of energy increases
Solution Approach 1:
The system applies energy periodically in controlled bursts to accelerate the drum to a known speed, then disconnects the motor to measure coast time. This periodic energy application allows accurate load measurement while minimizing total energy consumption, as the motor operates only during brief acceleration phases rather than continuously.
Solution Approach 2:
The drum's natural deceleration due to friction and load inertia is utilized to provide the measurement signal. Instead of requiring continuous energy input to maintain rotation for measurement, the system lets the drum coast naturally after a brief energy input, converting the load's own inertial properties into the measurement mechanism.
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 improves load detection accuracy by mitigating machine variation, temperature, motor stall, and friction effects, reducing errors and preventing loss of light garments, while adjusting cycle parameters based on load size and fabric type.
Implementation Method 1
measuring parameters associated with the speed... accelerate a drum to a predetermined rotational speed, remove power from the motor, measure the time it takes the drum to coast to a stop, and use time and energy values to achieve the predetermined speed to calculate a load mass
Data Source
AI summary
A method and apparatus determines a load size of a laundry load located in a laundry treating appliance having a drum defining a treatment chamber that is rotated by a motor based on a given amount of energy applied to the motor, and a measurement of coast time after the given amount of energy is removed.