Propeller Pitch Sensing With Non-Translating Distance Sensors
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Solution Overview
Problem
Existing propeller blade pitch sensing systems are heavy and mechanically complex, utilizing hydraulic actuation and position sensors like RVDT or LVDT, which do not meet lightweight and low-complexity requirements.
Innovation Solution
A sensing system with a target portion having a profile that changes with distance along an axis, using non-translating distance sensors to determine the pitch angle of propeller blades, allowing for a lightweight and low-complexity blade angle sensing system that operates independently of rotational speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hydraulic actuation systems with RVDT or LVDT position sensors are used to control propeller blade pitch, then reliable pitch angle sensing is achieved, but the system becomes heavy and mechanically complex
Solution Approach 1:
The patent replaces mechanical position sensors (RVDT/LVDT) with optical distance sensors that measure the position of a target portion with a specific profile. This substitution eliminates complex mechanical feedback mechanisms while maintaining sensing reliability through optical measurement of the target's characteristic profile as it translates with piston movement
Solution Approach 2:
The patent extracts the essential sensing function from complex hydraulic-mechanical sensor assemblies and isolates it to a simple target portion with a specific profile attached to the piston. The distance sensor only needs to measure distance to this simplified target, removing unnecessary mechanical complexity while preserving the core pitch angle measurement capability
2Reliability
If duplex rotary variable differential transformer (RVDT) or linear variable differential transformer (LVDT) sensors are used, then aircraft safety and dispatchability requirements are met, but the system weight increases
Solution Approach 1:
The patent replaces heavy mechanical transformers (RVDT/LVDT) with lightweight optical distance sensors. The optical sensor measures the position of the target portion with a specific profile, providing the necessary feedback signal without the weight penalty of traditional mechanical sensors, thus reducing overall system weight while maintaining safety compliance
Solution Approach 2:
The patent creates a simplified optical copy of the position measurement function. Instead of using complex mechanical transformers that physically convert displacement to electrical signals, the system uses an optical distance sensor to measure the position of a target with a characteristic profile, providing an equivalent measurement capability with reduced weight
3Adaptability or versatility
If calibration is performed at aircraft level upon pilot demand, then operational flexibility is provided, but system complexity and operational procedures become more complex
Solution Approach 1:
The patent enables the sensing system to be self-calibrating through the characteristic profile of the target portion. As the piston translates and the target moves through its range, the distance sensor naturally captures the profile's geometric characteristics, allowing automatic determination of reference positions without requiring external calibration equipment or complex procedural steps
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 system provides a lightweight and reliable means to determine propeller blade pitch angles with reduced mechanical complexity, offering improved accuracy and resilience through redundant sensing, suitable for aircraft applications.
Implementation Method 1
comprises at least one distance sensor for sensing a distance between the distance sensor and the outer surface of the target portion, wherein the sensed distance varies as the target portion translates axially
Data Source
AI summary
A sensing system and a method of sensing. The sensing system has a sensor apparatus and a target portion for sensing by the sensor apparatus. The target portion is integral with, or configured for coupling to, a component of an assembly so as to translate along an axis, and the target portion has an outer surface which has a profile that changes with distance along the axis. The sensor apparatus is configured for non-translating mounting adjacent the target portion, and has at least one distance sensor. The method comprises sensing a distance between the distance sensor and the outer surface of the target portion, wherein the sensed distance varies as the target portion translates axially, and outputting a signal in dependence on the sensed distance.