Rotorcraft Retraction Jack Shock Absorption

Solution Overview

Problem

Conventional rotorcraft landing gear systems fail to effectively absorb high-speed landing impacts, as the shock absorbers are overwhelmed by excessive vertical stresses, leading to potential catastrophic events, and enhancing the damper to withstand such stresses results in increased size, weight, and cost.

Innovation Solution

A retraction cylinder that can transform into a shock absorber by using a movable unlocking member and hydraulic piping to connect with a compression chamber, allowing it to dampen vertical stresses even when not subjected to them, thereby compensating for the limitations of the shock absorber during high-speed landings.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the shock absorber is dimensioned to withstand extreme vertical stresses during high-speed landings, then the absorption capability is improved, but the size, weight and cost become prohibitive

Engineering Contradiction:

Improveabsorption capabilityVSAvoidweight

Core Design Contradiction:

ReliabilityVSWeight of moving object

Solution Approach 1:

The retraction cylinder is designed to perform dual functions: normal retraction operations and shock absorption during high-speed landings. By incorporating a movable unlocking member that can be activated by vertical stress, the retraction cylinder transforms from a single-function component into a multi-functional system that provides both retraction and damping capabilities, eliminating the need for a separate oversized shock absorber

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The invention merges the retraction cylinder with shock absorption functionality by integrating a movable unlocking member and hydraulic connection to the shock absorber's compression chamber. This combination allows the retraction cylinder to participate in absorbing vertical shocks during high-speed landings, consolidating multiple functions into a unified system rather than requiring separate components

Inventive Principle:

Principle #5Merging (Combining)

2Reliability

If the shock absorber is dimensioned to withstand extreme vertical stresses during high-speed landings, then the absorption capability is improved, but the size becomes prohibitive

Engineering Contradiction:

Improveabsorption capabilityVSAvoidsize

Core Design Contradiction:

ReliabilityVSVolume of moving object

Solution Approach 1:

The retraction cylinder is designed to perform dual functions: normal retraction operations and shock absorption during high-speed landings. By incorporating a movable unlocking member that can be activated by vertical stress, the retraction cylinder transforms from a single-function component into a multi-functional system that provides both retraction and damping capabilities, eliminating the need for a separate oversized shock absorber

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The invention merges the retraction cylinder with shock absorption functionality by integrating a movable unlocking member and hydraulic connection to the shock absorber's compression chamber. This combination allows the retraction cylinder to participate in absorbing vertical shocks during high-speed landings, consolidating multiple functions into a unified system rather than requiring separate components

Inventive Principle:

Principle #5Merging (Combining)

3Stability of the object's composition

If the piston is blocked to maintain position, then the positioning stability is improved, but the ability to dampen horizontal stress is lost

Engineering Contradiction:

Improvepositioning stabilityVSAvoidstress damping capability

Core Design Contradiction:

Stability of the object's compositionVSAdaptability or versatility

Solution Approach 1:

The locking system transitions from a static blocked state to a dynamic unlockable state. The movable unlocking member allows the piston to switch between locked (for positioning stability) and unlocked (for stress damping) states based on operational conditions, enabling the system to adapt between maintaining position and absorbing shocks

Inventive Principle:

Principle #15Dynamics

4Reliability

If a separate shock absorber is added to handle high-speed landing impacts, then the absorption capability is improved, but the device complexity increases

Engineering Contradiction:

Improveabsorption capabilityVSAvoidsystem complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The invention merges the retraction cylinder with shock absorption functionality by integrating a movable unlocking member and hydraulic connection to the shock absorber's compression chamber. This combination allows the retraction cylinder to participate in absorbing vertical shocks during high-speed landings, consolidating multiple functions into a unified system rather than requiring separate components

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The retraction cylinder is designed to perform dual functions: normal retraction operations and shock absorption during high-speed landings. By incorporating a movable unlocking member that can be activated by vertical stress, the retraction cylinder transforms from a single-function component into a multi-functional system that provides both retraction and damping capabilities

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 retraction cylinder effectively dampens vertical stresses during high-speed landings, preventing damage and maintaining the landing gear's functionality without the need for a larger, heavier damper, thus ensuring safety and reducing costs.

Implementation Method 1

a control chamber (22) filled with a first fluid, said control chamber being separated from the return means by a movable unlocking member (24), said movable unlocking member sliding so that the retraction cylinder fulfills a damping function when a control pressure exerted by said first fluid on said movable unlocking member is greater than a return pressure exerted by said return means

Methodology Applied

Scientific EffectHydraulic pressure: Hydraulic Press

Implementation Method 2

a shock absorber (14) disposed on a rotorcraft landing gear strut... a compression chamber (15) of the shock absorber... hydraulic piping which connects the control chamber to a compression chamber (15) of the shock absorber

Methodology Applied

Scientific EffectHydraulic damping: Hydraulic Press

Data Source

PatentEP2048078B1Retraction jack, rotorcraft landing gear equipped with such a retraction jack

Publication Date: 2010.04.21 EUROCOPTER FRANCE SA

Figure 1~4
Figure 2~5

AI summary

The jack (20) has a control chamber (22) separated from a recall unit (23) i.e. weighted spring, by a movable blocking component (24), where the chamber is filled with fluid. The component is slid to allow the jack to perform a damping function when the control pressure exerted by the fluid on the component is higher than a recall pressure exerted by the recall unit. A hydraulic tubing (21) connects the control chamber to a compression chamber (15) of a damping device (14) arranged on an undercarriage strut of a rotorcraft. The recall unit has a pressurized chamber filled with another fluid.