Compressor Transmission Starting Unit for Axial Load Management
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Solution Overview
Problem
High-speed compressor transmissions face challenges in rapidly building a load-bearing lubricating film during start-up, leading to increased axial loads on pressure collars, which reduces efficiency and shortens the service life due to delayed lubricating film formation and high axial thrusts caused by gas forces.
Innovation Solution
A transmission system with a starting unit that includes a secondary thrust bearing, which is activated during start-up to bypass the primary axial bearing, using a hydrostatic plain bearing with self-lubricating materials and a movable piston to rapidly establish a lubricating film, minimizing direct solid body friction and maximizing axial load absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If pressure collars are used for axial support in high-speed transmissions, then transmission efficiency is improved through reduced friction, but the service life is reduced due to delayed lubricating film formation during start-up
Solution Approach 1:
A secondary thrust bearing is introduced that activates during start-up to provide preliminary axial support before the primary pressure collar bearing becomes effective. This preliminary action prevents direct contact and solid body friction during the critical start-up phase when the lubricating film has not yet formed in the pressure collar, thereby extending bearing service life while maintaining transmission efficiency during normal operation
2Reliability
If hydrodynamic plain bearings are used to support high-speed shafts, then wear is reduced through lubricating film formation, but the bearing cannot effectively support axial loads at low speeds during start-up
Solution Approach 1:
A secondary thrust bearing acts as an intermediary during start-up operations, providing the necessary axial load support capability at low speeds when the primary hydrodynamic bearing cannot yet form an effective lubricating film. This intermediary bearing bridges the gap between standstill and the speed required for hydrodynamic film formation, after which it deactivates and the primary bearing takes over
3Productivity
If pressure collars are used for axial support, then transmission efficiency is improved, but axial loads during start-up cause increased wear and reduced service life
Solution Approach 1:
The bearing system is made dynamic by introducing a controllable secondary thrust bearing that can be activated and deactivated based on operating conditions. During start-up and shut-down phases, the secondary bearing is activated to share axial loads and reduce wear on the primary pressure collar. During normal high-speed operation, the secondary bearing is deactivated and the primary bearing handles all axial loads, maintaining transmission efficiency
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 rapid lubricating film formation at low speeds, effectively absorbing axial loads and reducing wear, thereby improving the starting behavior and extending the service life of the transmission by mechanically bypassing pressure collars during start-up and shut-down processes.
Implementation Method 1
The starting unit (5) comprises a pressurizable piston (10) which is movable in the axial direction between a support position in which it supports the output shaft (17) and absorbs axial loads of the output shaft (17)
Implementation Method 2
using a hydrostatic plain bearing with self-lubricating materials and a movable piston to rapidly establish a lubricating film, minimizing direct solid body friction
Implementation Method 3
The piston (10) can be acted upon with pressure oil on its side facing the first subchamber (11.1) in order to move it axially in the direction of the support position (10.1)
Data Source
Figure 1
Figure 2
AI summary
The invention relates to a transmission, in particular a compressor transmission, which is arranged between a drive motor and a driven unit; - with a driving and a driven shaft; wherein - the driving shaft is in drive connection with the driven shaft for speed/torque conversion; - the driven shaft is supported in the transmission by means of at least one primary axial bearing. The invention is characterized by the following features: - a starting unit is provided for absorbing axial loads on the driven shaft; - the starting unit comprises a secondary axial bearing; - the starting unit is designed such that, when actuated, the axial loads on the driven shaft are absorbed essentially completely by the secondary axial bearing.