External Hydraulic Propulsor Pitch Control With Reduced Rotor Weight
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Solution Overview
Problem
Existing rotary propulsor systems face inefficiencies due to the use of electromechanical actuators that increase the size and weight of components, reducing the weight efficiency and performance of the rotor system.
Innovation Solution
A hydraulic actuation system is employed to adjust propulsor blade pitch, eliminating the need for a pitch change shaft bearing assembly within the gearbox, using a hydraulic actuation system with an external pitch beam and guide rods to reduce component size and weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electromechanical actuators are used to adjust propulsor blade pitch, then the pitch control function is achieved, but the size and weight of components increase, reducing weight efficiency
Solution Approach 1:
The patent replaces electromechanical actuators with a hydraulic actuation system. A hydraulic actuator is positioned in the central opening of the rotor hub, with a piston coupled to the pitch change shaft. Hydraulic fluid is supplied to the actuator to move the piston, which rotates the pitch change shaft to adjust blade pitch. This hydraulic approach eliminates the need for bearing assemblies inside the gearbox, significantly reducing component weight and size while maintaining reliable pitch control.
2Ease of operation
If a pitch change shaft bearing assembly is included inside the gearbox, then the pitch change shaft can rotate, but the size and weight of the rotor hub and associated components increase
Solution Approach 1:
The patent extracts the bearing assembly from the internal gearbox location and relocates it to an external position on the pitch change shaft. The bearing assembly is positioned outside the rotor hub, allowing the pitch change shaft to rotate without requiring internal bearing support within the hub. This extraction eliminates the need for a large internal bearing assembly, reducing the rotor hub volume and overall component size while maintaining the rotation function.
3Reliability
If electromechanical actuators are used for pitch control, then pitch adjustment is achieved, but the device complexity and component size increase
Solution Approach 1:
The patent replaces complex electromechanical actuator assemblies with a simpler hydraulic actuation system. The hydraulic actuator consists of a cylinder and piston mechanism that directly converts hydraulic pressure into rotational motion of the pitch change shaft. This eliminates the need for motors, gearboxes, and bearing assemblies required by electromechanical actuators, significantly reducing device complexity while maintaining reliable pitch adjustment capability.
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 results in lighter, more efficient propulsor components, enhancing aircraft performance by reducing the size and weight of the propulsor assembly and associated components.
Implementation Method 1
Hydraulic fluid is supplied to a hydraulic actuation cylinder positioned in the central opening to rotate a pitch change shaft
Implementation Method 2
the rotor assembly includes guide rods to provide additional resistance to bending loads
Data Source
AI summary
A rotor assembly for a rotary wing aircraft includes a rotor hub including a hub arm and a central opening. The rotor assembly further includes a hydraulic actuation cylinder positioned in the central opening, a pitch change shaft assembly including a pitch change shaft positioned partially within the hydraulic actuation cylinder, a pitch beam coupled to a distal end of the pitch change shaft and configured to be coupled to a rotor blade rotatably mounted to the hub arm. The rotor assembly additionally includes at least one guide rod coupled to the rotor hub and slidably coupled to an opening in the pitch change shaft.