Magnetorheological Haptic Brake Layout for High Torque in Small Spaces
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Solution Overview
Problem
Haptic operating devices with magnetorheological braking systems face challenges in achieving high braking torque while maintaining a compact design and low manufacturing costs, particularly at small diameters where the magnetic field saturation limits the braking torque.
Innovation Solution
A haptic operating device with a magnetorheological braking system featuring a stator and rotor unit design, where the electrical coil is wound axially to increase the core cross-section, allowing a stronger magnetic field and higher braking torque within the same installation space, and using a magnetically conductive outer brake component to enhance field concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the diameter of the shaft is reduced to achieve a compact design, then the installation space is reduced, but the magnetic field saturation limits the braking torque that can be generated
Solution Approach 1:
The patent transitions from a conventional radial magnetic field configuration to an axial magnetic field configuration. The coil is wound around the shaft in the axial direction, generating a magnetic field that extends along the axial dimension rather than radially. This dimensional change allows the magnetic field to utilize the full length of the shaft, effectively increasing the magnetic circuit area without increasing the radial diameter, thereby maintaining compact installation space while overcoming magnetic saturation limits
Solution Approach 2:
The patent introduces adjustable braking torque through a controllable magnetic field strength. By dynamically adjusting the current through the coil, the magnetic field strength can be varied to optimize braking torque according to operational requirements. This dynamic control allows the system to adapt braking force to different operating conditions while maintaining a compact design
2Force
If longer rollers are used to increase braking torque, then the magnetic field acts over a larger area, but the magnetic field strength per transmission surface decreases due to distribution over the longer roller surface
Solution Approach 1:
The patent shifts the magnetic field generation from a radial configuration to an axial configuration. The coil is wound axially around the shaft, creating a magnetic field that extends along the axial dimension. This allows the full length of the shaft to contribute to the magnetic circuit, effectively increasing the magnetic field interaction area without requiring longer radial rollers, thereby maintaining magnetic field strength concentration while achieving high braking torque
Solution Approach 2:
The patent divides the magnetic circuit into multiple segments along the axial direction of the shaft. The coil is wound in axial segments, creating multiple magnetic field zones that act on different sections of the braking surface. This segmentation allows the magnetic field to be distributed along the axial length rather than concentrated radially, enabling longer effective interaction length without reducing field strength per unit area
3Force
If the coil diameter is increased to generate a stronger magnetic field, then the braking torque increases, but the installation space and device volume increase
Solution Approach 1:
The patent reorients the coil winding from a radial configuration to an axial configuration. Instead of increasing the radial diameter of the coil, the coil is wound around the shaft in the axial direction, extending along the length of the shaft. This dimensional reorientation allows the magnetic field to utilize the axial dimension for field generation, achieving strong braking torque without increasing the radial installation footprint, thereby maintaining a compact device volume
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 configuration enables the generation of higher braking forces in a smaller installation space or equally high forces in a more compact design, improving the torque per installation volume and allowing for considerable braking forces in very small spaces.
Implementation Method 1
Magnetorheological fluids use spherical particles with a manufacturing-related diameter of 1 to 10 μm, although the particle size and shape are not uniform. If such a magnetorheological fluid is subjected to a magnetic field, the carbonyl iron particles of the magnetorheological fluid interlink along the magnetic field lines, so that the rheological properties of the magnetorheological fluid (MRF) are significantly influenced depending on the shape and strength of the magnetic field (transmissible shear stresses).
Implementation Method 2
The first brake component (2) has a core (21) made of a magnetically conductive material, which extends in the axial direction (20), and an electrical coil (26a) wound around the core (21) in the axial direction (20). The magnetic field (8) of the electrical coil (26a) extends transversely to the axial direction (20) through the first brake component (2).
Implementation Method 3
The outer brake component (3) is made of a magnetically conductive material, through which the magnetic field (8) is conducted. The magnetic field (8) is concentrated in the region of the rolling elements (11) in order to be able to generate a high braking torque.
Data Source
Figure 1a~1f
Figure 2~3
Figure 4a~4c
AI summary
The invention relates to a haptic operating device (100) comprising a rotatable operating part (101), a magnetic field source (26), and a magnetorheological braking device (1) for braking a rotational movement of the operating part (101). The magnetorheological braking device (1) comprises two braking components (2, 3) which can be rotated relative to one another and one of which is coupled to the rotatable operating part (101). The second brake component (3), acting as an outer brake component (3), surrounds the first brake component (2) that acts as an inner brake component (2). A closed magnetorheological brake chamber (110) provided with a magnetorheological medium (6) is formed between the two brake components (2, 3) and has a peripheral braking gap (5).