Magnetorheological Brake Star Contour for High Torque Density
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Solution Overview
Problem
Existing magnetorheological braking devices face limitations in generating high braking moments, particularly at small diameters, due to magnetic field saturation and inefficient magnetic flux distribution, leading to disproportionate reductions in braking effect with weaker fields.
Innovation Solution
A magnetorheological braking device with a stationary mount and brake components featuring a core and casing part, utilizing magnetic field concentrators in the form of a star contour and rolling elements, which are fixedly connected to enhance magnetic field concentration and generate high braking moments with a smaller installation space.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the diameter of the shaft is reduced to achieve a compact device, then the installation space is reduced, but the magnetic field saturation occurs more rapidly leading to a reduced maximum braking moment
Solution Approach 1:
The patent applies local quality by introducing magnetic field concentrators (star-shaped elements) at specific locations within the gap where the magnetic field needs to be intensified. These concentrators locally enhance the magnetic field strength in the magnetorheological fluid without requiring an overall increase in the device diameter, thus resolving the contradiction between compact size and braking moment generation.
Solution Approach 2:
The patent transitions from a uniform magnetic field distribution to a dimensionally varied field by introducing star-shaped magnetic field concentrators with multiple points extending into the gap. This creates a multi-dimensional magnetic field structure that concentrates flux at specific locations, enabling higher braking moments in a compact diameter.
2Area of stationary object
If the length of rolling members is increased to enhance magnetic field action, then the magnetic field acts on a larger area, but the magnetic field strength is reduced due to distribution across the longer area
Solution Approach 1:
Instead of using long rolling members that distribute the magnetic field weakly over a large area, the patent employs shorter star-shaped magnetic field concentrators that concentrate the magnetic field strength at specific local points in the gap. This local concentration approach maintains high field strength while achieving effective braking through targeted action points.
Solution Approach 2:
The patent replaces symmetric cylindrical rolling members with asymmetric star-shaped magnetic field concentrators. The star shape creates concentrated magnetic field points at its tips, generating localized high-strength magnetic fields that are more effective for braking than the distributed field from symmetric rollers.
3Force
If a stronger magnetic field is applied to overcome saturation and increase braking moment, then the braking effect improves, but the device complexity and energy consumption increase
Solution Approach 1:
The patent introduces magnetic field concentrators as intermediary elements between the electromagnetic coil and the magnetorheological fluid. These concentrators act as mediators that amplify and redirect the magnetic field flux, achieving high braking moments without requiring proportionally higher coil currents or more complex magnetic field generation systems.
Solution Approach 2:
The patent replaces the need for mechanically larger components (longer rollers, larger diameter shafts) with a magnetic field concentration mechanism using star-shaped concentrators. This substitution allows achieving the same or better braking effect through magnetic field optimization rather than mechanical scaling.
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 device achieves a significant increase in braking moment without increasing the device's diameter, allowing for higher torque generation with reduced space and cost-effective production, while maintaining reliability and scalability.
Implementation Method 1
When such a magnetorheological fluid is impinged by a magnetic field, the carbonyl iron particles of the magnetorheological fluid form a chain along the magnetic field lines so that the rheological properties of the magnetorheological fluid (MRF) are significantly influenced as a function of the shape and intensity of the magnetic field (transmissible shear stresses).
Implementation Method 2
Received in the brake housing is (at least) one electric coil. The magnetorheological medium in the duct is influenced by a magnetic field.
Data Source
AI summary
A magnetorheological braking device has two braking components that are continuously rotatable relative to one another. A first braking component extends in the axial direction and the second braking component includes a hollow casing extending around the first braking component. A peripheral gap is filled with a magnetorheological medium. The first braking component has an electric coil and a magnetically conductive core which extends in the axial direction. A star contour with magnetic field concentrators on the core and/or on the shell part project into the gap, which results in a peripheral gap region with a variable gap height. The electric coil is wound around the core such that a magnetic field runs through the core and the magnetic field concentrators and through the gap into a wall of the casing. A star contour is formed by a stack of star plates.