Nested Shaft Coupling for Compact Motor Compressor Alignment
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Solution Overview
Problem
Integrated turbocompressor units face challenges with axial alignment, vibration mode coupling, gas leaks, and axial bulk due to rigid and flexible couplings, which restrict compactness, maintenance, and safety, especially when handling combustible gases.
Innovation Solution
A compact integrated motor compressor unit design featuring a connecting shaft within the main shaft, supported by bearings, with a single axial abutment and dismountable attachment means, eliminating the need for radial openings and enhancing axial rigidity and leak resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a flexible coupling is used to connect the rotor and driven shaft, then alignment problems are eliminated and vibration modes are preserved, but radial openings are required in the housing for maintenance which create gas leak risks
Solution Approach 1:
The connecting shaft is nested inside the driven shaft, with the coupling zone positioned within the hollow interior of the driven shaft. This nesting arrangement allows the flexible coupling to be accessed and maintained from the axial end of the housing without requiring radial openings, thereby eliminating gas leak risks while preserving the benefits of flexible coupling for alignment and vibration.
2Ease of operation
If a flexible coupling is used to connect the rotor and driven shaft, then alignment tolerance is improved, but axial bulk increases by 35 to 40 cm
Solution Approach 1:
The connecting shaft is positioned inside the driven shaft, utilizing the hollow space within the driven shaft's interior. This nested configuration eliminates the need for additional axial space that would normally be required for a conventional flexible coupling, thereby reducing axial bulk while maintaining alignment tolerance benefits.
Solution Approach 2:
The coupling mechanism is moved from an axial arrangement to a radial arrangement, with the connecting shaft extending radially inward into the driven shaft's hollow interior. This dimensional repositioning allows the flexible coupling functionality to be achieved without increasing axial bulk.
3Length of moving object
If a rigid coupling is used to connect the rotor and driven shaft, then axial bulk is minimized, but perfect alignment is required during assembly
Solution Approach 1:
The connecting shaft is nested inside the driven shaft with its coupling zone positioned within the hollow interior. This nested flexible coupling arrangement maintains compact axial dimensions similar to rigid couplings while providing the alignment tolerance benefits of flexible couplings through the radial offset between the connecting shaft and driven shaft centerlines.
Data Source
AI summary
A motor compressor unit (1) comprises a motor (3) and a compressor (2) which are mounted in a common housing (4) sealed against the gas to be compressed. The motor (3) comprises a rotor (39) rotatably connected to a rotor (38) of the compressor (2). The rotor (38) of the compressor comprises a main shaft (11) and a connecting shaft (21) coaxial with the main shaft, the connecting shaft being placed at least partly inside the main shaft (11) so as to be radially spaced from the main shaft (11) and comprising a coupling zone (15) for coupling with the main shaft (11).