Aircraft Accessory Gearbox Actuator Mounting

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Solution Overview

Problem

The existing accessory gearbox design for aircraft wing flaps complicates maintenance by requiring disassembly of peripheral equipment to access the connection shaft between the piston rod and control rod, making it time-consuming and costly, and exposes the actuator to vibrations due to its overhang position.

Innovation Solution

The accessory gearbox design relocates the connection between the piston rod and control rod to the front, allowing direct access and mounting/demounting, reduces actuator overhang, and integrates fluid ducts within the gearbox casing to minimize space and enhance mechanical stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the connection shaft is located behind the actuator in region C, then the actuator can be mounted on the gearbox, but maintenance requires disassembly of peripheral equipment and is time-consuming

Engineering Contradiction:

Improveactuator mountingVSAvoidconnection shaft access

Core Design Contradiction:

Ease of manufactureVSEase of repair

Solution Approach 1:

The patent inverts the conventional arrangement by positioning the connection shaft in front of the actuator body rather than behind it. This allows maintenance personnel to access and handle the connection shaft directly from the front of the gearbox without needing to disassemble peripheral equipment, thereby resolving the contradiction between ease of manufacture and ease of repair.

Inventive Principle:

Principle #13The other way round (Inversion)

2Volume of moving object

If the connection shaft is located behind the actuator, then the actuator structure is compact, but the connection shaft is difficult to access and handle

Engineering Contradiction:

Improveactuator positioningVSAvoidconnection shaft handling

Core Design Contradiction:

Volume of moving objectVSEase of operation

Solution Approach 1:

The patent reverses the traditional positioning of the connection shaft relative to the actuator body. By placing the connection shaft in front of the actuator, the design prioritizes ease of operation and accessibility during maintenance over compact positioning, allowing direct access without compromising the actuator's functional integration.

Inventive Principle:

Principle #13The other way round (Inversion)

3Ease of repair

If the actuator is moved away from the gearbox towards the front, then access to the connection shaft is improved, but the actuator overhang increases making it vulnerable to vibrations

Engineering Contradiction:

Improveconnection shaft accessibilityVSAvoidactuator fixing strength

Core Design Contradiction:

Ease of repairVSReliability

Solution Approach 1:

The patent resolves this contradiction by inverting the spatial relationship: instead of moving the actuator away from the gearbox to improve access, the connection shaft is repositioned in front of the actuator body. This maintains the actuator's close positioning to the gearbox for vibration resistance while providing direct access to the connection shaft for maintenance.

Inventive Principle:

Principle #13The other way round (Inversion)

4Ease of repair

If peripheral equipment is dismounted to access the connection shaft, then the connection shaft becomes accessible, but maintenance time and costs increase

Engineering Contradiction:

Improveconnection shaft reachabilityVSAvoidmaintenance duration

Core Design Contradiction:

Ease of repairVSLoss of time

Solution Approach 1:

The patent eliminates the need for peripheral equipment disassembly by inverting the connection shaft position to the front of the actuator. This allows maintenance personnel to directly access and service the connection shaft without any disassembly operations, significantly reducing maintenance time and costs while maintaining full reachability.

Inventive Principle:

Principle #13The other way round (Inversion)

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 design simplifies and accelerates maintenance by providing direct access to the connection shaft, reduces maintenance costs, and improves the actuator's resistance to engine vibrations by eliminating the need for peripheral equipment disassembly and reducing overhang.

Implementation Method 1

the circulation of fluids on either side of the piston 23 causes said piston to move in one direction or the other

Methodology Applied

Scientific EffectHydraulic actuation: Hydraulic Press

Data Source

PatentUS9758238B2Accessory drive gearbox for controlling the flaps of an aircraft

Publication Date: 2017.09.12 SAFRAN HELICOPTER ENGINES

AI summary

An accessory gearbox for a turboshaft engine of an aircraft, the gearbox including a casing, an aircraft wing flap control rod arranged so as to slide axially inside the gearbox and an actuator for driving the control rod which is mounted on the casing, the actuator including a hollow body, a piston which is arranged so as to move in translation inside the body and a piston rod which is connected to the piston and extends at least in part outside the body of the actuator the piston rod being connected to the control rod, wherein the actuator is arranged between the connection of the piston rod and the control rod, and the casing of the gearbox.