Laundry Machine Belt Slip Detection for Torque-Adaptive Drive Control

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Solution Overview

Problem

Existing laundry treatment machines face issues with undesirable slippage between the belt and drive shaft, particularly during startup, leading to belt wear and potential failure due to aging belts and tension mechanisms, which can cause sudden machine failure.

Innovation Solution

A laundry treatment machine with a slip detector connected to the control system that detects slip by analyzing torque, speed, and power curves, allowing for control adjustments such as reversing the direction of rotation and reducing speed to minimize slippage, thereby maintaining belt tension and preventing premature failure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If the drum drive is operated with high torque during startup, then the drum acceleration is improved, but slippage between the belt and drive shaft increases

Engineering Contradiction:
Improvedrum accelerationVSAvoidbelt slippage
Core Design Contradiction:
SpeedVSReliability

Solution Approach 1:

The control system dynamically adjusts the drive torque based on real-time slip detection. When slip is detected, the controller automatically reduces the drive torque to prevent belt damage, while still allowing adequate acceleration during normal operation. This dynamic adjustment resolves the contradiction between needing high acceleration and preventing slippage.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The slip detector provides continuous feedback to the controller about belt slippage conditions. The controller uses this feedback to adjust the drive torque in real-time, reducing torque when slip is detected and maintaining normal torque when no slip occurs. This closed-loop feedback system enables the drum to accelerate effectively while preventing harmful slippage.

Inventive Principle:
Principle #23Feedback

2Reliability

If the belt is tensioned tightly to prevent slippage, then slippage is reduced, but the risk of belt breakage due to aging and tension increases

Engineering Contradiction:
Improveslip preventionVSAvoidbelt durability
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The system uses the existing slip detector and controller to automatically adjust drive torque based on slip conditions, eliminating the need for additional tensioning mechanisms or higher-strength belts. The control system serves itself by detecting slip and adjusting torque accordingly, preventing both slippage and belt over-stressing.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The control system changes the operational parameter (drive torque) based on detected slip conditions. When slip is detected, torque is reduced to prevent further slippage and belt damage. This parameter adjustment allows the system to maintain reliable operation without increasing belt tension, thereby preserving belt durability.

Inventive Principle:
Principle #35Parameter changes

3Reliability

If slip detection and control adjustment systems are added, then slippage is reduced, but device complexity increases

Engineering Contradiction:
Improveslip detection and controlVSAvoidsystem components
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The slip detector and controller serve multiple functions: detecting slip, determining torque curves, controlling drive torque, and preventing belt damage. By making these components multi-functional, the system achieves reliable slip detection and control without adding numerous separate devices, thereby limiting the increase in complexity.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The slip detection function is integrated with the existing torque control system. The controller combines slip detection, torque curve determination, and drive control into a unified system. This merging of functions reduces the number of separate components needed compared to having independent systems for each function.

Inventive Principle:
Principle #5Merging (Combining)

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

The solution effectively reduces the occurrence and severity of slippage, extending the machine's service life without requiring additional or higher-quality components, allowing for planned maintenance and preventing sudden belt failures.

Implementation Method 1

slippage between the belt and the drive shaft... Due to the friction caused by slippage, this effect can also be self-reinforcing because the belt can heat up due to the friction

Methodology Applied
Scientific EffectFriction: Friction

Implementation Method 2

a drum drive connected to the drum by a belt for transmitting torque

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP3960922B1Laundry treatment machine and method for its operation
Publication Date: 2024.05.08 MIELE & CO KG
  • EP3960922B1 patent drawingFigure 1
  • EP3960922B1 patent drawingFigure 2

AI summary

The invention relates to a laundry treatment machine (2) comprising a drum (6) rotatable about a drum axis (4), a drum drive (10) connected to the drum (6) by means of a belt (8) for torque transmission, and a control unit for controlling the drum drive (10), wherein the drum drive (10) has a drive shaft (14) rotatable about a drive axis (12) and connected to the belt (8) for torque transmission, characterized in that the laundry treatment machine (2) has a slip detector connected to the control unit for signal transmission for detecting slippage between the belt (8) and the drive shaft (14), wherein the control unit is designed and configured such that the drum drive (10) can be controlled by the control unit depending on the detection of slippage between the belt (8) and the drive shaft (14). The invention further relates to a method for operating a laundry treatment machine (2).