Turbojet Engine Mounting with Converging Rods for Casing Torsion
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Solution Overview
Problem
Existing turbojet engine mounting systems generate significant torsional forces on the engine casing, necessitating improved designs to minimize these forces and enhance stability and safety.
Innovation Solution
A propulsion unit design featuring a mounting pylon with a front arch and lateral connecting rods that converge on the propeller axis, distributing moments generated in the propulsion unit to minimize overload on the engine casing, combined with a rear engine attachment for additional stability and safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a rigid pylon structure is used to attach the engine to the wing, then structural strength is improved, but torsional forces on the engine casing increase
Solution Approach 1:
The rigid pylon structure is segmented into multiple connection points (first connection point on the engine casing, second connection point on the pylon, and third connection point on the wing). By distributing the structural connection across multiple points, the system maintains overall structural strength while reducing concentrated torsional forces on the engine casing. The connecting rod acts as a separate structural element that transfers loads without imposing torsional moments on the casing.
Solution Approach 2:
A connecting rod is introduced as an intermediary element between the engine casing and the pylon structure. This connecting rod serves as a mediator that transfers aerodynamic and inertial forces from the engine assembly to the pylon and wing, while its articulated connections prevent the transmission of torsional forces to the engine casing, thus protecting the casing from harmful torsional loads.
2Stability of the object's composition
If multiple connecting rods are used to distribute moments, then stability is improved, but device complexity increases
Solution Approach 1:
The moment distribution function is segmented across three distinct connection points (first, second, and third connection points) rather than using a single complex attachment mechanism. Each connection point handles specific force components, with the connecting rod specifically managing moment distribution. This segmentation provides stability while keeping each individual connection relatively simple.
Solution Approach 2:
The connection system extends into three-dimensional space with the connecting rod positioned at a specific longitudinal distance from the propeller plane. This spatial arrangement creates a lever arm that naturally distributes moments across multiple dimensions, enhancing stability without requiring complex mechanical mechanisms at each connection point.
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 design effectively applies moments at the propeller center, reducing casing flexing and enhancing overall stability and safety by distributing loads and moments efficiently.
Implementation Method 1
the longitudinal axes of the lateral connecting rods and the central connecting rod converge on the longitudinal axis at the level of the center of the propeller... the moments generated in the propulsion unit are applied at the center of the propeller and therefore do not overload the engine casing
Implementation Method 2
a central connecting rod arranged at the median plane, where the central connecting rod has a rear end mounted articulated to the mounting pylon by a first rear connection point and a front end mounted articulated to the casing by a first front connection point
Implementation Method 3
two lateral connecting rods arranged on either side of the median plane, where each inner connecting rod has a rear end mounted hinged to the extension which is on the same side of the median plane by a second rear connection point and a front end mounted hinged to the casing by a second front connection point
Data Source
Figure 1~2
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AI summary
The invention relates to an aircraft propulsion assembly (100) having a turbojet engine comprising a casing (112) and a propeller (53), a mounting pylon (104) with a front arch (108) with two extensions (108b) which extend around the casing (112) over at least 90°, a central connecting rod (120) having a rear end (120a) articulated to the mounting pylon (104) and a front end (120b) articulated to the casing (112), and two lateral connecting rods (122), where each inner connecting rod (122) has a rear end (122a) articulated to the extension (108b) which is on the same side of the median plane (P) and a front end (122b) articulated to the casing (112) and where the longitudinal axes of the lateral connecting rods (122) and of the connecting rod central (120) converge on a longitudinal axis (X) at the center of the propeller (53). With such an arrangement, the moments generated in the propulsion unit are applied at the center of the propeller and therefore do not overload the engine casing.