Hydraulic Control Surface Actuation Without Rack-and-Pinion Wear
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Solution Overview
Problem
Rack and pinion actuator systems experience frictional wear, leading to reduced precision and increased maintenance needs, and face challenges in operating within confined spaces of thinner wing aircraft without compromising gear tooth loads and manufacturing tolerances.
Innovation Solution
A hydraulic actuator system using band members connected to pistons within cylinders, with a direct drive four-way servo valve and accumulator, applies hydraulic fluid pressure to control control surfaces without imparting impact or frictional wear, allowing precise control and operation within smaller spaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a rack and pinion actuator system is used to control control surfaces, then the control surface rotation can be achieved through gear engagement, but frictional wear occurs between the gears leading to reduced precision and increased maintenance needs
Solution Approach 1:
The patent replaces the traditional rack and pinion gear system with a direct drive system where a motor connects directly to the control surface shaft through a coupling unit. This eliminates the gear engagement mechanism that causes frictional wear, thereby maintaining control surface rotation capability while preserving gear precision and reducing maintenance needs.
Solution Approach 2:
The coupling unit serves as an intermediary component between the motor and the control surface shaft. It transmits rotational force while accommodating misalignment and reducing mechanical stress, thereby eliminating the need for gear engagement and preventing frictional wear between gear components.
2Volume of moving object
If the pinion gear diameter is reduced to operate within confined space of thinner wing aircraft, then space constraints are satisfied, but manufacturing close tolerances and handling high gear tooth loads become more difficult
Solution Approach 1:
The patent eliminates the pinion gear entirely by implementing a direct drive system. The motor connects directly to the control surface shaft through a coupling unit, removing the need for gear tooth engagement. This substitution allows the actuator system to be compact without compromising manufacturing tolerances or load handling capabilities.
Solution Approach 2:
The invention changes the fundamental operating parameters of the actuation system by transitioning from a gear-based mechanical advantage system to a direct electromagnetic drive. This parameter change allows for a more compact actuator design that does not require large diameter pinion gears, thereby satisfying space constraints while avoiding the manufacturing precision issues associated with small, high-load gears.
3Length of stationary object
If the pinion gear diameter is reduced to operate within confined space, then the actuator fits within thinner wing structures, but high gear tooth loads and tolerance maintenance become conflicting design challenges
Solution Approach 1:
The patent replaces the gear-based transmission system with a direct drive configuration where the motor shaft connects directly to the control surface shaft through a coupling unit. This substitution eliminates gear tooth loads entirely, allowing the actuator to be designed for compact installation within thinner wing structures without compromising load capacity.
Solution Approach 2:
The coupling unit acts as an intermediary that directly transmits motor torque to the control surface shaft without requiring gear intermediaries. This direct connection maintains full torque transmission capability while eliminating the need for large diameter pinion gears, thereby accommodating thinner wing structures without sacrificing strength or load handling capacity.
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 reduces maintenance costs by minimizing frictional wear and enables precise control surface operation within smaller aircraft structures without compromising gear tooth loads or manufacturing tolerances, enhancing reliability and operational efficiency.
Implementation Method 1
A hydraulic actuator system applies hydraulic fluid pressure to control control surfaces
Implementation Method 2
A hydraulic actuator system using band members connected to pistons within cylinders, with a direct drive four-way servo valve and accumulator
Data Source
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AI summary
An actuator system for controlling a control surface of an aircraft, which includes a control structure which defines the control surface and the control structure has an axis of rotation about which the control structure can rotate relative to the aircraft. A first actuator assembly has a first actuator arm and a second actuator assembly has a second actuator arm. The first actuator assembly and the second actuator assembly are spaced apart from one another along the axis of rotation. The first actuator arm is connected to a first band member and the first band member is connected to the control structure on a first side of the axis of rotation and the second actuator arm is connected to a second band member and the second band member is connected to the control structure on a second opposing side of the axis of rotation.