Hysteresis Coupling Torque Transfer for Tank Cleaning Drive Systems

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Solution Overview

Problem

Magnetic couplings with permanent magnets face challenges in transferring torque effectively, especially at high speeds and starting torque, leading to slipping and inefficiency in drive systems for tank cleaning heads.

Innovation Solution

A hysteresis coupling using a rotating magnetic inductor and a ferromagnetic or magnetic hysteresis part connected to the gear input shaft, allowing for reliable torque transfer and adjustable torque and speed, independent of relative speeds, with the option of using permanent or electromagnets and a non-magnetic housing material.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If a magnetic coupling with permanent magnets is used to transfer torque, then the coupling can operate at high speeds, but it slips and shakes when starting torque exceeds maximum torque

Engineering Contradiction:
Improverotation speedVSAvoidtorque transfer reliability
Core Design Contradiction:
SpeedVSReliability

Solution Approach 1:

The patent changes the magnetic coupling type from synchronous (permanent magnets) to hysteresis coupling, which allows for variable torque characteristics. The hysteresis coupling can accommodate varying starting torques and speeds by utilizing the hysteresis loop properties of ferromagnetic materials, enabling reliable torque transfer during startup while maintaining high-speed operation capability.

Inventive Principle:
Principle #35Parameter changes

2Stability of the object's composition

If synchronous coupling with permanent magnets is used, then the coupling parts can move together, but the coupling slips when starting torque exceeds maximum torque

Engineering Contradiction:
Improvemagnetic engagement stabilityVSAvoidtorque transfer capability
Core Design Contradiction:
Stability of the object's compositionVSForce

Solution Approach 1:

The patent transitions from synchronous coupling with fixed magnetic properties to hysteresis coupling where the magnetic properties can vary during the magnetization cycle. This allows the coupling to maintain stable magnetic engagement while accommodating varying torque demands, particularly during startup when torque requirements are highest.

Inventive Principle:
Principle #35Parameter changes

3Force

If the coupling is dimensioned to transfer high torque, then the starting torque can be handled, but the coupling becomes larger and more complex

Engineering Contradiction:
Improvetorque capacityVSAvoidcoupling size
Core Design Contradiction:
ForceVSDevice complexity

Solution Approach 1:

The hysteresis coupling utilizes the nonlinear magnetic properties of ferromagnetic materials to achieve variable torque capacity without proportionally increasing size. The hysteresis loop allows the material to store and release magnetic energy, enabling high torque transfer during startup while maintaining a compact design suitable for high-speed operation.

Inventive Principle:
Principle #35Parameter changes

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

Ensures consistent torque transfer at start-up and varying speeds, maintaining structural integrity and allowing for maintenance-free operation with adjustable energy content and magnetic field strength, enhancing the reliability of the drive system.

Implementation Method 1

a hysteresis coupling comprising a rotating magnetic inductor driven by the propeller, or a hysteresis part in the housing which drives a rotating part mounted outside the housing, either of a ferromagnetic hysteresis material or a magnetic part

Methodology Applied
Scientific EffectMagnetic hysteresis: Magnetic Hysteresis

Implementation Method 2

the rotation produced by the propeller is transferred to the gear via a magnetic coupling having coupling parts, the one coupling part of which being disposed inside the housing in the liquid channel and the other coupling part of which being disposed outside the housing

Methodology Applied
Scientific EffectMagnetic coupling: Magnetism

Data Source

PatentEP1973675B1A drive system for a cleaning head disposed in a tank
Publication Date: 2015.06.17 ALFA LAVAL TANK EQUIP
  • EP1973675B1 patent drawingFigure 1
  • EP1973675B1 patent drawingFigure 2
  • EP1973675B1 patent drawingFigure 3

AI summary

When, according to the invention, constructing a drive system for rotating the cleaning head in a tank and allowing the system to comprise a hysteresis coupling having two magnetic parts which are present inside the liquid space (4) and outside this, respectively, a completely liquid-tight separation between the housing (2) and the gear (14) may be ensured. The magnetic part (8, 18) of the hysteresis coupling may be formed by electromagnets, and with a displaceable (13) position of the one part relative to the other part (11, 19) the coupling may be adjusted with respect to the transferred torque and/or speed.