Magnetic Brake Composite Drag Ring Torque Control
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Solution Overview
Problem
Hysteresis brakes exhibit low torque, non-linearity, low power dissipation, and cogging issues, making them unsuitable for applications requiring precise control and high braking power, especially in winding and unwinding systems.
Innovation Solution
The design incorporates a thicker drag ring with high remanence and coercivity materials, eddy current braking, and a control system that linearizes torque output by measuring and interpolating torque curves, along with a cooling system to manage heat dissipation and reduce residual magnetism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional hysteresis brake design is used, then the brake operates contactlessly without wear, but the torque output is relatively low
Solution Approach 1:
The drag ring is constructed from composite materials including magnetic particles suspended in a binding material within a structural matrix. This composite structure increases the effective magnetic interaction between the drag ring and magnetic field, thereby generating higher braking torque while maintaining the contactless operation that prevents wear
Solution Approach 2:
The patent changes key parameters of the hysteresis brake including using materials with high remanence and coercivity, optimizing the magnetic field strength, and adjusting the drag ring geometry. These parameter changes enable the brake to produce higher torque output while maintaining reliable contactless operation
2Device complexity
If conventional hysteresis brake design is used, then the structure is simple, but the torque output is non-linear and dependent on rotation speed
Solution Approach 1:
The control system continuously monitors the actual torque output and rotation speed, then adjusts the magnetic field strength accordingly using stored torque curves. This feedback mechanism linearizes the torque output and eliminates speed dependence while maintaining relatively simple brake hardware
Solution Approach 2:
Torque curves are pre-measured and stored in memory for various operating conditions. During operation, the controller retrieves and applies the appropriate pre-calculated correction factors, enabling precise linear torque control without complex real-time calculations or additional mechanical components
3Loss of energy
If conventional hysteresis brake design is used, then the brake operates with minimal energy loss, but power dissipation is low
Solution Approach 1:
The brake utilizes the periodic nature of magnetic hysteresis cycles to dissipate energy as heat through controlled magnetic field reversal. By optimizing the frequency and amplitude of these periodic magnetic cycles, the system achieves high power dissipation capability while maintaining efficient energy conversion and minimal wasted losses
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 provides increased braking power, linear torque control, and reduced hysteresis and cogging, enabling efficient deceleration and tension management in rotating systems while maintaining low maintenance and dust-free operation.
Implementation Method 1
A coil between the inner and outer stators is connected to a current source. The drag ring is rotatably supported on the shaft and has an impeller attached to one side of the drag ring.
Implementation Method 2
The impeller may be made of a material having high thermal conductivity, such as copper or aluminum.
Implementation Method 3
Hysteresis brakes are a common type of magnetic brake that have been in use for many years. However, hysterisis brakes have several drawbacks, including relatively low torque, hysteresis, non-linearity, low power dissipation and high cogging.
Data Source
AI summary
A magnetic brake has an outer stator surrounding an inner stator with a circumferential slot between the outer stator and the inner stator. A coil is provided in the inner stator adjacent to the circumferential slot. A drag plate is attached to a rotatable shaft extending centrally through the inner stator. A drag ring joined to the drag plate extend into the circumferential slot. The drag ring may be an annular cylindrical ring section separate from the drag plate. Vent holes pass through the inner stator adjacent and parallel to the shaft. The magnetic brake uses both hysteresis and eddy current braking.