Magnetorheological Brake Sealing for Low Basic Torque Haptics
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Solution Overview
Problem
Magnetorheological braking devices for rotary movements often have high basic torque, which can lead to user fatigue and require significant increases in braking torque for haptic feedback, making them unsuitable for small haptic operating devices like computer mice, where a lower basic torque and higher torque ratio are needed for precise control.
Innovation Solution
A magnetorheological braking device with a sealed receiving space filled with magnetorheological particles and gas, featuring a low-friction sealing device with a contacting sealing lip and a high proportion of magnetorheological particles, reducing basic torque and allowing for increased maximum torque without liquid, and a sensor device with a magnetic ring unit and magnetic field sensor for precise position detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a magnetorheological braking device uses a liquid carrier medium, then the magnetorheological particles are well-distributed, but the basic torque becomes too high for small haptic operating devices
Solution Approach 1:
The patent replaces the liquid carrier medium with a gas-filled sealed receiving space. This eliminates the liquid friction and damping that caused high basic torque, while still allowing magnetorheological particles to be suspended and distributed throughout the gap between the rotary body and axle unit. The gas environment provides minimal resistance to motion while enabling particle suspension.
Solution Approach 2:
The patent changes the physical state of the carrier medium from liquid to gas. This parameter change fundamentally alters the friction characteristics and damping properties of the system, reducing the basic torque to acceptable levels for small haptic operating devices like computer mice while maintaining the ability to generate braking torque when needed.
2Ease of manufacture
If the receiving space is not sealed, then assembly is easier, but magnetorheological particles escape and the device fails
Solution Approach 1:
The patent employs a sealing device comprising a sealing lip that contacts the rotary body to create a sealed receiving space. This flexible sealing mechanism maintains particle containment while accommodating the rotational movement and dimensional tolerances of the components, enabling both reliable operation and practical assembly.
3Reliability
If a contacting sealing lip is used, then sealing is effective, but friction increases and basic torque rises
Solution Approach 1:
By replacing the liquid carrier medium with gas, the patent reduces the friction at the sealing interface. The gas environment minimizes adhesive friction between the sealing lip and rotary body, allowing effective sealing with minimal contact pressure and thus keeping the basic torque low.
Solution Approach 2:
The change from liquid to gas carrier medium fundamentally alters the tribological conditions at the sealing interface. Gas provides much lower friction and damping than liquid, enabling the sealing lip to maintain effective contact for particle containment while generating minimal frictional torque.
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 significantly reduces basic torque while maintaining high maximum braking torque, enhancing user experience by providing precise haptic feedback with lower operational effort and reducing user fatigue in small haptic devices.
Implementation Method 1
The magnetorheological medium comprises magnetorheological particles and gas and essentially consists of them. The magnetorheological particles change their rheological properties in response to a magnetic field.
Implementation Method 2
The sensor device has a magnetic ring unit and a magnetic field sensor arranged inside the axle unit
Data Source
AI summary
A magnetorheological braking device for braking rotational movements, with an axle unit and a rotary body which is rotatable about the axle unit. The rotatability of the rotary body can be braked in a targeted manner by means of a magnetorheological braking apparatus having a coil unit. A receiving space is formed between the axle unit and the rotary body, which receiving chamber is provided with a magnetorheological medium, the magnetorheological medium comprising magnetorheological particles and gas as a filling medium. The receiving space with the magnetorheological medium is sealed between the axle unit and the rotating body by a sealing device with a sealing unit having a contacting sealing lip.