Laundry Drum Load Weight Sensing With Shock Absorber Slip Compensation
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Solution Overview
Problem
Existing methods for determining the load weight of a washing machine's laundry drum are inaccurately influenced by friction dampers, particularly due to slipping friction linings, which introduce non-linear forces and affect measurement precision.
Innovation Solution
A method using a spring-piston friction damper with a control device that evaluates the displacement sensor's time curve to detect slipping of the shock absorber during loading, determining a change value caused by slipping and compensating for it to accurately calculate the load weight, allowing the use of lower static friction dampers and avoiding the need for cost-intensive oil-hydraulic dampers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If friction dampers are used to dampen vibrations during loading, then vibration damping is improved, but measurement precision deteriorates due to non-linear forces from slipping friction linings
Solution Approach 1:
The control device performs preliminary detection of the friction lining's position state during the loading process. By monitoring the displacement sensor signal for characteristic patterns indicating slipping, the system proactively identifies when the friction damper is in a non-linear state and applies appropriate compensation algorithms to correct measurement errors, thereby maintaining measurement precision while using cost-effective friction dampers
Solution Approach 2:
The invention changes the parameter evaluation approach by not only measuring displacement magnitude but also analyzing the time-profile characteristics and rate of change of displacement signals. This allows the control device to distinguish between normal loading displacement and displacement caused by friction lining slipping, enabling accurate load weight determination despite the non-linear forces from friction dampers
2Measurement precision
If oil-hydraulic dampers are used to avoid non-linear forces, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The invention replaces expensive, complex oil-hydraulic dampers with simpler, cheaper friction dampers. By implementing software-based compensation algorithms that detect and correct for friction lining slipping, the system achieves acceptable measurement precision using low-cost friction dampers, thereby reducing overall device complexity and cost while maintaining functional performance
Solution Approach 2:
The invention substitutes a purely mechanical solution (oil-hydraulic dampers) with a hybrid approach combining simple friction dampers and electronic control. The control device uses displacement sensor data and algorithmic processing to compensate for the non-linear behavior of friction dampers, replacing the need for complex mechanical damping systems with a more economical electromechanical solution
3Object-affected harmful factors
If friction dampers with lower static friction are used, then noise is reduced, but measurement accuracy worsens due to increased slipping
Solution Approach 1:
The control device continuously monitors the displacement sensor signal during loading and applies feedback compensation. By detecting characteristic patterns in the time-profile of displacement signals that indicate friction lining slipping, the system dynamically adjusts the measurement calculation to compensate for slipping effects, thereby maintaining measurement precision even when using low-friction dampers that produce less noise
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 enables precise determination of the load weight by compensating for the disruptive non-linear damper force, reducing noise and eliminating the need for expensive speed-dependent dampers, while ensuring accurate measurement of the load weight.
Implementation Method 1
vibrations of the oscillating system are damped against a device housing of the domestic appliance by means of at least one shock absorber
Implementation Method 2
vibrations of the oscillating system are damped
Implementation Method 3
measured values are provided by means of a displacement sensor which indicate a displacement of the oscillating system in relation to a reference position
Data Source
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AI summary
The invention relates to a method for determining a loading weight (B) of an oscillating system (16) of a domestic appliance (1) for treating items of laundry (4), in which method oscillations of the oscillating system (16) are damped against an appliance housing (6) of the domestic appliance (1) by means of at least one shock absorber (10, 11), and in which method measured values are provided by means of a displacement sensor (17), which measured values indicate a displacement of the oscillating system (16) with respect to a reference position, and the determination of the loading weight (B) takes place by means of a control device (14) using the measured values, wherein a temporal sequence of the measured values is evaluated by the control device (14) during a loading operation of the oscillating system (16) and slipping of the shock absorber (10, 11) during loading of the oscillating system (16) is detected using the temporal sequence, wherein a change value (24), caused by the slipping, of the displacement is determined by the control device (14) and is compensated for in the determination of the loading weight (B).