Multi-Pole Rotary Brake Layout for Higher Torque Density
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Solution Overview
Problem
Existing magneto-rheological fluid brakes have a limited torque to volume ratio due to a single magnetic pole design, restricting their application ranges.
Innovation Solution
A controllable rotary brake design featuring two non-magnetically permeable isolating rings, a shaft, an even number of magnetic field generating portions, and at least one resistance disc, with magneto-rheological fluid layers filling between the resistance disc and the isolating rings, allowing for expanded magnetic field action areas and increased torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single magnetic pole design is used in magneto-rheological fluid brake, then the device complexity is reduced, but the torque to volume ratio deteriorates due to limited magnetic field acting area
Solution Approach 1:
The magnetic field generating portion is divided into multiple magnetic poles (at least two poles: first magnetic pole and second magnetic pole). Each pole independently generates magnetic fields that act on different regions of the magneto-rheological fluid, thereby expanding the total acting area and increasing the torque to volume ratio without significantly increasing device complexity
Solution Approach 2:
The patent extends the magnetic field generation from a single-point or single-region source to multiple distributed poles arranged in specific spatial configurations. This multi-dimensional arrangement allows magnetic fields to act on the magneto-rheological fluid from multiple locations simultaneously, expanding the effective acting area and improving torque density
2Ease of manufacture
If the outer ring surface or end surfaces of the rotor are used as working surfaces, then the manufacturing is simplified, but the contact area with magneto-rheological fluid is limited, reducing the torque output
Solution Approach 1:
The rotor is equipped with multiple resistance discs arranged in different spatial positions rather than relying on a single outer ring surface. Each resistance disc provides an additional contact surface with the magneto-rheological fluid, thereby expanding the total contact area and torque generation capability while maintaining simple disc-shaped structures that are easy to manufacture
Solution Approach 2:
The patent transitions from using only the outer ring surface or end surfaces (two-dimensional surfaces) to incorporating multiple resistance discs positioned at different radial and axial locations. This three-dimensional distribution of resistance surfaces significantly increases the total contact area with the magneto-rheological fluid, thereby enhancing torque output
3Power
If magnetic field acting area is expanded to increase torque, then the torque to volume ratio improves, but the device volume increases, affecting compactness
Solution Approach 1:
Instead of using one large magnetic field generating structure, the system divides the magnetic field generation into multiple smaller poles and distributes multiple resistance discs throughout the available space. This segmentation allows the magnetic field to act on the magneto-rheological fluid at multiple locations within a compact volume, increasing torque density without proportionally increasing overall device volume
Solution Approach 2:
The patent employs a nested arrangement where resistance discs are positioned within the magnetic field regions created by the magnetic poles. The inner components (resistance discs) are placed within the volume defined by the outer magnetic field generating structure, maximizing the utilization of available space and achieving high torque output in a compact configuration
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 design enhances the torque to volume ratio and expands application ranges by increasing the acting area of the magneto-rheological fluid, resulting in a more effective and versatile brake system.
Implementation Method 1
Magnetic rheological fluid (MRF) is a suspension liquid formed by micron-sized magnetic particles, carrier fluid (e.g., mineral oil), and surfactants. The magnetic rheological fluid may activate the magnetic particles in the carrier fluid under the action of an external magnetic field to change the arrangement of the magnetic particles in the carrier liquid. Such that the viscosity of the magnetic rheological fluid may be adjusted.
Implementation Method 2
Two ends of each of the magnetic field generating portions are tightly fitted to the corresponding penetrating holes of the two non-magnetically permeable isolating rings. The at least one magneto-rheological fluid layer contacts the at least one resistance disc and one end of each of the magnetic field generating portions.
Data Source
AI summary
A controllable rotary brake includes two non-magnetically permeable isolating rings, a shaft, an even number of magnetic field generating portions, at least one resistance disc, and at least one magneto-rheological fluid layer. The non-magnetically permeable isolating rings are spaced apart from each other in an axial direction, and each has a bottom wall. An even number of penetrating holes are formed on the bottom wall. The shaft is rotatably inserted in and adapted to pivot relative to the non-magnetically permeable isolating rings. Two ends of each magnetic field generating portion are tightly fitted to the corresponding penetrating holes. The resistance disc is sleeved on the shaft and is spaced apart from one of the non-magnetically permeable isolating rings. The magneto-rheological fluid layer fills between the resistance disc and one of the non-magnetically permeable isolating rings and contacts the resistance disc and one end of each magnetic field generating portion.