Harmonic Drive Brake Assembly for Precise Backlash-Free Actuation
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Solution Overview
Problem
Existing brake assemblies for vehicles, particularly aircraft, face challenges in efficiently controlling braking forces and maintaining compactness while minimizing gear backlash and maximizing braking operations per second.
Innovation Solution
A brake assembly that incorporates a motor and a harmonic drive to transfer torque to a disc stack, featuring a disc stack with rotor and stator discs, and an actuator assembly that uses a piston to compress the disc stack, allowing for fine control of braking forces through linear motion conversion from rotary motion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional in-line actuators are used to compress the disc stack, then the actuator assembly can be configured in a compact manner, but gear backlash increases and braking operations per second decrease
Solution Approach 1:
The patent employs a harmonic drive mechanism that dynamically converts rotary motion from the motor into linear motion of the piston through flexible spline engagement. This dynamic motion conversion eliminates gear backlash while enabling precise control of braking forces, thereby increasing braking operations per second without excessive complexity
Solution Approach 2:
The harmonic drive acts as an intermediary mechanism between the motor and the piston, using flexible splines and wave generators to translate rotational input into linear output motion. This intermediary mechanism resolves the contradiction by providing smooth, backlash-free motion conversion that enhances productivity while maintaining manageable device complexity
2Measurement precision
If a harmonic drive is used to transfer torque from the motor to the disc stack, then gear backlash is reduced and braking control precision is improved, but the actuator assembly complexity increases
Solution Approach 1:
The patent replaces traditional rigid gear mechanisms with a harmonic drive system that uses flexible spline engagement and wave generator motion. This substitution eliminates gear backlash and provides superior braking force control precision, while the modular nature of the harmonic drive keeps the overall complexity manageable
Solution Approach 2:
The harmonic drive changes the motion parameters from rotary to linear through the flexible spline mechanism, enabling precise control of piston displacement and braking force. This parameter transformation achieves high measurement precision for braking control while the standardized harmonic drive components limit the increase in device complexity
3Power
If the motor generates high rotary speed, then power output is increased, but the responsiveness and sensitivity to braking commands decrease
Solution Approach 1:
The harmonic drive provides dynamic motion conversion that translates high-speed rotary input from the motor into controlled linear motion of the piston. The flexible spline mechanism inherently filters out high-frequency variations, improving responsiveness and sensitivity to braking commands while maintaining high power output capability
Solution Approach 2:
The wave generator in the harmonic drive creates controlled elastic deformation in the flexible spline, producing a vibration-like motion that enables smooth, responsive translation of motor output to piston movement. This mechanical vibration mechanism enhances sensitivity to control commands while preserving motor power output
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 enables precise control of braking forces, improves responsiveness and sensitivity, reduces gear backlash, and allows for more compact actuator assembly configurations compared to traditional in-line actuators.
Implementation Method 1
an actuator assembly configured to convert rotary motion produced by the motor into linear motion to cause translation of the piston
Data Source
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AI summary
In some examples, a brake assembly includes an actuator assembly configured to cause the translation of a piston to compress a disc stack. The actuator assembly is configured to generate a first torque around a motor axis using a motor and generate a second torque from the first torque using a harmonic drive. The actuator assembly may include a gear set configured to cause a linear actuator to translate the piston using the second torque. In some examples, the actuator is configured to translate the piston along a compression axis different from the motor axis.