Turbojet Cold Stream Flow Path Radial Crevice Mounts
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Solution Overview
Problem
Existing connection methods between the cold flow channel and the exhaust casing in turbojet engines require complex assemblies and many references, leading to increased maintenance complexity and potential mechanical strength issues due to excessive force transmission.
Innovation Solution
A connection system using yokes with radially oriented lugs on the exhaust casing's outer shroud, allowing connecting rods to deform radially and transmit forces along the neutral fiber, reducing the load on the rods and facilitating relative movements between the cold flow channel and the exhaust casing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If connecting rods are attached to the exhaust casing by means of assemblies with radial axes and bored ends, then the connecting rods gain rotational freedom and axial displacement capability, but the number of references increases and maintenance complexity increases
Solution Approach 1:
The invention merges the axis and the bored end into a single integrated yoke structure. The yoke is directly formed with the bore on the exhaust casing, eliminating the need for separate axis components, inserts, and screws. This consolidation reduces the number of references while maintaining the same functional capabilities of rotational freedom and axial displacement.
Solution Approach 2:
The yoke structure serves multiple functions simultaneously: it provides the attachment point for the connecting rod, allows rotational movement, accommodates axial displacement, and transmits forces. By making the yoke a multi-functional component, the invention reduces the need for multiple specialized parts, thereby simplifying the overall assembly.
2Adaptability or versatility
If connecting rods are used to attach the cold flow channel to the exhaust casing, then the connection allows relative displacements due to thermal expansion, but excessive forces may develop in the connecting rods
Solution Approach 1:
The invention introduces dynamic characteristics to the connection system through the yoke structure. The yoke allows the connecting rods to rotate and deform radially, transforming a rigid connection into a more flexible, dynamic one. This dynamic capability enables the system to accommodate thermal expansions and contractions while reducing excessive force transmission to the connecting rods.
Solution Approach 2:
The invention changes the mechanical parameters of the connection by allowing rotational movement and radial deformation. By modifying the degree of freedom and flexibility of the connection, the system can better absorb thermal stresses without transmitting excessive forces to the connecting rods, thereby protecting them from overload.
3Ease of manufacture
If the direction of force transmission by connecting rods is not tangent to the exhaust casing, then mechanical integration is simplified, but forces are transmitted with a lever arm creating torque harmful to mechanical strength
Solution Approach 1:
The invention applies local quality by making the yoke orientation specific at the attachment points. The yokes are positioned and oriented such that the connecting rods transmit forces tangentially to the exhaust casing at these specific locations. This local optimization at the attachment points eliminates harmful torques while maintaining overall mechanical integration simplicity.
Data Source
Figure 1~2
Figure 3~5
AI summary
Bypass turbojet engine comprising a cylindrical cold stream flow path supported by link rods (3) which are attached to a cylindrical outer shell ring of an exhaust case (1) at attachment points (4), characterized in that the attachment points for the exhaust case are crevice mounts the lugs of which extend radially from said outer shell ring, the bore of said crevice mounts being directed in the direction of the generatrices of the outer shell ring.