Lead-Lag Hydraulic Damper With Centrifugal Damping Compensation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Prior art helicopter rotor blade lead-lag dampers provide constant damping independent of rotational speed, leading to high heat generation and the need for larger, heavier dampers to dissipate heat, which is undesirable.
Innovation Solution
A piston-rod assembly with a valve spool and sleeve that regulates fluid flow between ports in response to centrifugal forces, allowing for variable damping control, reducing the size and weight of the damper while maintaining effective damping performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If constant damping is provided independent of rotational speed, then damping performance is maintained, but heat generation increases and damper size and weight increase
Solution Approach 1:
The damper employs a centrifugal force mechanism where a mass rotates with the rotor, and its centrifugal force varies with rotational speed to automatically adjust the damping coefficient. At higher speeds, the centrifugal force increases, reducing damping to minimize heat generation. At lower speeds, damping is maintained for stability. This dynamic adjustment resolves the contradiction between maintaining damping performance and reducing heat generation.
Solution Approach 2:
The damping coefficient is changed as a function of rotational speed through the centrifugal force mechanism. The system transitions from constant damping to variable damping by changing the physical parameter (damping coefficient) based on operating conditions, thereby reducing heat generation at high speeds while maintaining performance when needed.
2Reliability
If constant damping is provided independent of rotational speed, then damping performance is maintained, but damper size and weight increase
Solution Approach 1:
The centrifugal force mechanism allows the damper to use a smaller, lighter structure because it leverages the rotor's rotational energy to provide variable damping. The rotating mass is integrated with the rotor system, and the damping force is generated dynamically without requiring a large, heavy constant-damping structure.
Solution Approach 2:
The damper uses the rotor's own rotational energy to generate the centrifugal force needed for damping adjustment. The system is self-regulating, using the operating conditions (rotational speed) to automatically adjust its damping characteristics without external control systems, reducing overall system weight and complexity.
3Reliability
If constant damping is provided independent of rotational speed, then damping performance is maintained, but device complexity increases
Solution Approach 1:
The centrifugal force mechanism provides a simple, elegant dynamic solution where a mass on a rotating arm automatically adjusts damping based on speed. This mechanical self-regulation is simpler than electronic control systems or complex valve arrangements, reducing device complexity while maintaining variable damping performance.
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 effectively manages damping based on rotor speed, reducing heat generation and damper size, resulting in a more efficient and lightweight damping system for helicopter rotor blades.
Implementation Method 1
The channel has an axial width of a magnitude configured to variably regulate fluid flow (e.g., hydraulic fluid flow) between the first port and the second port to variably control dampening of the piston-rod in response to centrifugal forces applied to the valve spool, generated by rotation of the rotor.
Data Source
AI summary
A piston assembly for a lead-lag damper for a blade mounted on a rotor of a helicopter includes a piston-rod that has an inside surface and a piston-head that extends radially outward therefrom. The piston-rod has two ports extending therethrough on opposing sides of the piston-head. A sleeve is positioned in the piston-rod and has two annular passages that communicate with the respective ports. A valve spool is disposed in and slidingly engages the sleeve. The valve spool has a channel which is in variable fluid communication with two passages. The piston assembly includes a biasing member that biases the valve spool axially away from it. The channel has an axial width configured to variably regulate fluid flow between the two ports to control dampening of the piston-rod in response to centrifugal forces applied to the valve spool.