Compact Gearbox Design for Aircraft Windshield Wiper Systems
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Solution Overview
Problem
Aircraft windshield wiper systems face challenges in achieving a compact design while ensuring effective cleaning within a specific angle, as existing designs often result in mechanical interference and inefficient torque transmission due to external gearing, leading to potential overcurrent issues.
Innovation Solution
A compact gearbox design incorporating a brushless direct current (BLDC) motor with an internally cut sector gear and a gear train featuring a first and second gear with different diameters, where the sector gear includes an internal geared groove and stoppers, allowing for hard mechanical stops and overcurrent trip logic to prevent overrotation, thereby reducing the overall envelope and enhancing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If external gearing is used in the gearbox design, then the structure is simpler to manufacture, but mechanical interference occurs and torque transmission becomes inefficient
Solution Approach 1:
The patent inverts the conventional external gearing approach by using internal gearing where the sector gear engages with the gear train from the inside. This inversion eliminates mechanical interference between components while maintaining manufacturing feasibility, thereby resolving the contradiction between ease of manufacture and torque transmission efficiency
2Volume of moving object
If the gearbox envelope is reduced for compactness, then the system size is minimized, but mechanical interference increases
Solution Approach 1:
The patent employs nesting by placing the gear train inside the sector gear's internal circumference. This nested arrangement allows the gear train to be contained within the compact envelope of the sector gear, minimizing the overall gearbox volume while preventing mechanical interference through the internal gearing configuration
3Productivity
If the sweep angle is increased for better cleaning coverage, then the cleaning effectiveness is improved, but the risk of overcurrent conditions increases
Solution Approach 1:
The patent incorporates stoppers that preliminarily define the maximum sweep angle before overcurrent conditions can occur. By pre-establishing mechanical limits on the sector gear's rotation, the system prevents excessive current draw while maintaining adequate cleaning coverage, thus resolving the contradiction between productivity and reliability
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 a compact and efficient windshield wiper system with reduced mechanical interference, effective torque transmission, and prevention of overcurrent conditions, ensuring reliable operation within the required sweep angle.
Implementation Method 1
a brushless direct current (BLDC) motor with a motor output shaft gear
Data Source
AI summary
A windshield wiper system (WWS) is provided and includes a brushless direct current (BLDC) motor with a motor output shaft gear, a gear train and an internally cut sector gear. The gear train includes a first gear, which has a first diameter and engages with the motor output shaft gear, and a second gear, which has a second diameter that is shorter than the first diameter and rotates with the first gear. The internally cut sector gear is coupled with an output shaft and formed to define an internal geared groove that engages with the second gear.