Electric Brake Actuator Layout Using Harmonic Drive Backlash Control
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Solution Overview
Problem
Existing brake assemblies for vehicles, particularly aircraft, face challenges in achieving compact actuator configurations and efficient braking control due to the alignment of motor and compression axes, leading to potential gear backlash and reduced braking operations per second.
Innovation Solution
The integration of a harmonic drive system that generates a second rotary torque at a lower speed and opposite direction, coupled with a gear set and linear actuator, allows for a separate compression axis, enabling a more compact actuator configuration and reducing gear backlash, while the electric motor generates a first rotary torque around a motor axis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a meshed gearbox is used to transfer torque from the motor to the linear actuator, then the actuator configuration can be compact, but gear backlash occurs and braking operations per second are reduced
Solution Approach 1:
The patent replaces the meshed gearbox mechanical system with a harmonic drive system. The harmonic drive uses wave generation and flexspline engagement instead of traditional gear meshing, eliminating the backlash problem while maintaining compact actuator configuration. This substitution of mechanical systems resolves the contradiction between compactness and reliability.
2Device complexity
If the motor axis and compression axis are aligned, then the actuator configuration is simpler, but the braking operations per second are reduced
Solution Approach 1:
The patent introduces a spatial dimension separation by displacing the motor axis from the compression axis. This creates a non-collinear arrangement where the motor shaft axis and the linear actuator compression axis are separated by a specific distance. This dimensional change allows for faster braking operations while managing actuator configuration complexity.
3Productivity
If the motor runs at high speed, then braking operations per second increase, but control sensitivity and responsiveness are reduced
Solution Approach 1:
The harmonic drive acts as an intermediary between the high-speed motor and the linear actuator. It provides torque conversion and speed reduction while maintaining precise control, enabling the system to achieve both high braking operations per second and fine control sensitivity through the intermediate harmonic drive mechanism.
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
This configuration enhances braking control sensitivity and responsiveness by allowing finer control of compression forces and increasing braking operations per second, compared to systems using meshed gearboxes.
Implementation Method 1
a harmonic drive configured to generate a second rotary torque in response to the first rotary torque
Implementation Method 2
a linear actuator mechanically coupled with the gear set, wherein the linear actuator is configured to generate linear motion along a compression axis
Data Source
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.