Turbine Engine Trunnion Centring Device
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Solution Overview
Problem
The assembly of the low-pressure turbine module in turbo machines is challenging due to the lack of visibility during the mounting of the inter-shaft bearing, leading to risks of hard contact and assembly incidents, with existing methods being either costly or lacking precision.
Innovation Solution
A device comprising a holding ring and a measurement system that allows for precise centring of the shaft relative to the trunnion, using a tactile measurement system and a calibration model to ensure accurate positioning down to one-hundredth of a millimetre, avoiding hard contact with the outer ring and its components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional centring methods (using a rule) are used, then the assembly process is simple, but the positioning precision is insufficient leading to hard contact and assembly incidents
Solution Approach 1:
A centring device is introduced as an intermediary tool between the shaft and the outer ring. This device includes a holding ring that fits around the trunnion and a measurement system with a radial finger that contacts the shaft, providing a mediating mechanism for precise position transfer and control during assembly.
Solution Approach 2:
The measurement system creates a physical copy or representation of the shaft's position through the radial finger contact point. This allows the position information to be transferred and measured indirectly through the holding ring structure, enabling precise positioning without direct complex instrumentation on the shaft itself.
2Measurement precision
If laser measurement instruments are used, then positioning precision is improved, but the cost and operational complexity increase significantly
Solution Approach 1:
The measurement system uses simple, inexpensive mechanical components (holding ring, radial finger, tightening means) rather than expensive laser instruments. These components are designed for single-use during the assembly operation, after which they can be removed and the holding ring reused if needed, avoiding the high cost of sophisticated measurement equipment.
Solution Approach 2:
The patent replaces optical measurement systems (laser instruments) with a purely mechanical measurement system. The radial finger mechanically contacts the shaft and transfers position information through the holding ring structure, substituting complex optical-electronic systems with simple mechanical leverage and geometry.
3Ease of operation
If the outer ring is heated for dilation, then the insertion of rollers is facilitated, but precise positioning becomes even more critical to avoid contact
Solution Approach 1:
The centring device is installed and positioned before the heating and dilation process begins. The holding ring is tightened around the trunnion and the radial finger is positioned against the shaft to establish the correct position while the components are still at normal temperature and dimensions, ensuring precision is set before thermal expansion occurs.
Solution Approach 2:
The measurement system with the radial finger acts as a protective mechanism that prevents hard contact by providing continuous position feedback during the heating and insertion process. The device cushiones against positioning errors by maintaining a controlled mechanical relationship between the shaft and outer ring even as thermal expansion occurs.
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 enables precise and safe assembly of the low-pressure turbine module by ensuring accurate centring, reducing the risk of assembly incidents and maintaining the integrity of the bearing components, while avoiding the need for costly laser instrumentation.
Implementation Method 1
a holding ring (17) configured to be fixed around the trunnion (11) by tightening
Implementation Method 2
a means of measurement (19) supported by the holding ring (17) and configured to measure the position of an outer surface of said shaft (5) along a radial direction
Data Source
AI summary
The invention concerns a device for assembling a turbine engine, intended to centre a shaft of a second module relative to a longitudinal axis (X) of a trunnion for a first module, the shaft having to be inserted along said longitudinal axis (X) via one end of the trunnion, wherein it includes a holding ring configured to be fixed around trunnion by tightening in such a way as to have a central axis of holding ring coincide with the longitudinal axis of the trunnion, and a means of measurement, supported by holding ring and configured to measure the position of an outer surface of the shaft along a radial direction relative to the central axis of the ring on a transverse plane (P) offset from holding ring, in such a way as to be located in front of the end of the trunnion when the device is installed on the trunnion. The invention also concerns the assembly formed by the device and a calibration model, along with an assembly procedure that uses same.