Brake Assembly Friction Coating Weight Reduction
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Solution Overview
Problem
Conventional brake assemblies for electric motors in aerospace applications are heavy and large due to the number and size of brake discs required, and they often need to be immersed in oil for operation, which is undesirable in weight-sensitive and high-load applications where rapid deceleration or stopping is necessary.
Innovation Solution
A brake assembly with a stack of brake elements coated with tungsten carbide to increase the coefficient of friction, allowing for a smaller number of elements and reduced compressive load, along with an electromagnetic actuator that can be serviced without removing the entire assembly, and designed to prevent contact between elements when not in use to avoid drag forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If traditional brake discs are used with low friction coefficient materials, then the brake assembly can be simpler in structure, but the weight and size of the assembly becomes undesirably large
Solution Approach 1:
The invention changes the friction coefficient parameter of the brake disc surface by applying a coating layer (such as tungsten carbide, titanium nitride, or diamond-like carbon) to increase the coefficient of friction from the traditional 0.1-0.2 to above 0.2. This parameter change allows the brake assembly to achieve the same braking force with fewer or smaller brake discs, thereby reducing weight and size while maintaining structural simplicity.
2Force
If more brake discs are used to achieve greater braking force, then the braking performance improves, but the weight and size of the assembly increases
Solution Approach 1:
By changing the surface friction coefficient through coating application, the invention enables fewer brake discs to generate the same braking force. The high friction coefficient material allows each disc to contribute more effectively to the total braking force, reducing the number of discs needed and thereby reducing overall assembly weight.
Solution Approach 2:
The invention uses composite construction where a base brake disc material is combined with a high-friction coating layer. This composite structure provides both the mechanical strength of the base material and the high friction surface properties of the coating, enabling effective braking with reduced component quantity and weight.
3Ease of manufacture
If traditional brake materials with low friction coefficient are used, then the manufacturing process is simpler, but the number of brake elements required increases leading to larger assembly size
Solution Approach 1:
The invention accepts a more complex manufacturing process involving surface coating application (such as detonation gun deposition, chemical vapor deposition, or physical vapor deposition) in exchange for significantly reducing the number of brake elements needed. The high friction coefficient achieved through coating allows compact brake assembly design, reducing the overall footprint and size of the brake system.
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 results in a lighter, more compact brake assembly with improved braking efficiency, capable of stopping high-speed motors quickly and efficiently without oil immersion, and allows for easier servicing with reduced part replacement and adjustment.
Implementation Method 1
the brake elements are provided, at least in part, with a surface coating which raises the coefficient of friction of the brake elements to a value greater than 0.2
Implementation Method 2
actuator means controlling the magnitude of a compressive load applied to the brake elements
Data Source
AI summary
A brake assembly for a motor, the brake assembly comprising a stack of brake elements, at least one of which is rotatable with an output shaft of the motor, in use, and at least one of which is non-rotatable relative to a housing, and actuator means controlling the magnitude of a compressive load applied to the brake elements, wherein the brake elements are provided, at least in part, with a surface coating which raises the coefficient of friction of the brake elements to a value greater than 0.2. The invention also relates to a brake assembly comprising a plurality of brake elements and an electromagnetic actuator arranged to permit control of a compressive load applied to the brake elements, wherein the actuator includes a winding located such that the brake elements are accessible without requiring removal of the winding from the motor.