MR Drum Brake Sealing and Shear Surface Design for Tactile Torque
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Solution Overview
Problem
Existing magnetically responsive (MR) drum brakes are limited by the number of shear surfaces, which restricts torque generation, and require expensive seals to prevent MR material migration.
Innovation Solution
A tactile feedback device (TFD) drum brake with enhanced torque generation capabilities, featuring a shaft, drum rotor, core, pole ring, and magnetically responsive material, along with improved magnetic seals to prevent MR material migration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing MR drum brakes use traditional seal structures, then the device structure is simple, but MR material migrates from the gap into the remainder of the device
Solution Approach 1:
The patent employs composite sealing structures combining magnetic seals and non-magnetic seals in specific configurations. The magnetic seal contains MR material within the gap using magnetic field containment, while non-magnetic seals provide structural support and additional containment. This composite approach prevents MR material migration while managing the complexity through functional specialization of different seal types.
Solution Approach 2:
The sealing system is divided into multiple segments including upper magnetic seals, lower magnetic seals, upper non-magnetic seals, and lower non-magnetic seals positioned at different locations around the drum brake assembly. This segmentation allows each seal to address specific migration pathways independently, improving overall containment effectiveness while distributing the complexity across modular components.
2Force
If existing MR drum brakes have only one or two shear surfaces, then the device structure is simple, but torque generation is limited
Solution Approach 1:
The patent transitions from traditional single-plane shear surfaces to a three-dimensional drum configuration with shear surfaces distributed across multiple cylindrical surfaces. The inner cylindrical surface and outer cylindrical surface of the drum provide additional shear areas, effectively utilizing the third dimension (radial direction) to multiply torque generation capacity without proportionally increasing device complexity.
Solution Approach 2:
The drum brake is divided into multiple shear surface segments including an inner cylindrical shear surface, an outer cylindrical shear surface, and potentially additional segmented shear surfaces. Each segment contributes independently to torque generation, allowing the system to achieve high total torque through the cumulative effect of multiple distributed shear interfaces rather than relying on a single large surface.
3Volume of moving object
If the drum brake size is reduced for compact design, then the device occupies less space, but torque generation capability decreases
Solution Approach 1:
The patent maximizes the utilization of the drum's three-dimensional geometry by creating shear surfaces on both the inner and outer cylindrical surfaces, as well as utilizing the axial length of the drum. This multi-surface approach allows compact drum dimensions while maintaining high torque generation through the cumulative shear area across multiple surfaces, effectively packing more functional area into a smaller volume.
Solution Approach 2:
The integration of magnetically responsive materials with high magnetic susceptibility enables more efficient torque generation per unit area. The MR material's ability to generate high shear stress in the presence of magnetic fields allows the compact drum design to achieve required torque levels through optimized material properties rather than relying solely on increased physical dimensions.
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 TFD drum brake achieves increased torque output and improved seal efficiency, allowing for a more compact design while preventing MR material migration and enhancing operational reliability.
Implementation Method 1
a magnetically responsive material disposed within the first gap and the second gap
Implementation Method 2
an upper magnetic seal and a lower magnetic seal. The upper magnetic seal is positioned to block MR material from moving from the second gap. The lower magnetic seal is positioned to block MR material from moving from the first gap
Data Source
Figure 1A
Figure 1B
Figure 2A
AI summary
A tactile feedback device (TFD) drum brake has a drum rotor that creates at least two gaps and at least four shear surfaces. Magnetically responsive (MR) material is disposed within the gaps. The TFD drum brake further has an upper and lower magnetic seal to prevent the migration of the MR material from the gaps. The drum rotor is thin and rapidly saturates when a magnetic flux is generated. Controllable torque is created when the drum rotor is saturated. The controllable torque provides feedback to an operator of vehicle with the TFD drum brake installed.