Centrifugal Impeller Layout for Lower Thrust Bearing Loss
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Turbo compressors face challenges in elongating the service life of bearings and increasing critical speed without shortening the axial length of impellers, due to high mechanical losses from thrust forces and inefficient bearing arrangements.
Innovation Solution
The turbo compressor employs a rotating shaft with axially spaced centrifugal impellers oriented such that their back sides face each other, using cylindrical roller bearings and a thrust bearing to reduce thrust loads, and strategically positions bearings to minimize mechanical losses and support radial loads effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If two impellers are arranged in the same orientation with back sides facing the same direction, then the compression efficiency is improved, but the thrust forces combine to generate a great thrust load that increases mechanical loss and shortens bearing service life
Solution Approach 1:
The patent applies the counterweight principle by arranging the second impeller in reverse rotation relative to the first impeller. This configuration causes the thrust forces generated by both impellers to act in opposite directions, thereby canceling each other out and significantly reducing the net thrust load on the bearing. The reverse rotation arrangement allows the impellers to function as counterbalancing elements that eliminate the harmful cumulative thrust effect while maintaining compression efficiency.
Solution Approach 2:
The patent employs inversion by reversing the rotational direction of the second impeller compared to the first impeller. Instead of both impellers rotating in the same direction, the second impeller rotates in the opposite direction, which inverts the direction of its thrust force. This inversion strategy transforms the harmful effect of combined thrust forces into a beneficial cancellation effect, reducing mechanical loss in the bearing while preserving the compression function.
2Reliability
If the number of bearings is increased to support larger thrust load and elongate bearing service life, then the reliability is improved, but the mechanical loss becomes larger
Solution Approach 1:
By arranging impellers in reverse rotation, the thrust forces are canceled out, reducing the load on bearings. This allows the use of fewer bearings with lower mechanical loss while still achieving reliable support for the reduced thrust load, thereby improving reliability without increasing energy loss.
3Speed
If the axial length of impellers is shortened to increase critical speed of rotating shaft, then the critical speed is improved, but the compression efficiency is lowered
Solution Approach 1:
The patent applies dynamics by introducing reverse rotation of the second impeller, which changes the dynamic characteristics of the rotating assembly. This dynamic configuration allows the impellers to generate opposing thrust forces that cancel each other, reducing the net load on the rotating shaft. As a result, the critical speed can be increased without shortening the axial length of the impellers, thereby maintaining compression efficiency while improving the critical speed parameter.
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 configuration reduces mechanical losses, elongates the service life of bearings, and increases critical speed without shortening the axial length of impellers, enhancing the compressor's efficiency and reliability.
Implementation Method 1
the bearings are cylindrical roller bearings and a thrust bearing, the cylindrical roller bearings being arranged at two axially spaced supporting positions respectively and supporting a radial load applied to the rotating shaft
Implementation Method 2
the thrust bearing supporting a thrust load applied to the rotating shaft
Data Source
AI summary
A first centrifugal impeller and a second centrifugal impeller are arranged in such an orientation that back sides of the first centrifugal impeller and the second centrifugal impeller face to each other. Bearings are cylindrical roller bearings and a thrust bearing. The cylindrical roller bearings are arranged at two axially spaced supporting positions respectively, and support a radial load applied to the rotating shaft. The thrust bearing supports a thrust load applied to the rotating shaft.