Multistage Screw Compressor Gearbox for Adjustable Stage Ratios
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Solution Overview
Problem
Conventional 3-wheel gearboxes in two-stage screw compressors limit the ability to adjust the gear ratio between compressor stages, leading to inefficiencies due to variable intermediate pressures, which result in over- or under-compression and significant efficiency losses when total power, final pressure, or volume flow changes.
Innovation Solution
A 4-wheel gearbox system with independent drives for each compressor stage, allowing adjustable gear ratios and flexible arrangement of stages, enabling optimal intermediate pressure control and reduced bearing loads through helical gearing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a conventional 3-wheel gearbox is used with a common drive wheel, then the structure is simple and the center distance is fixed, but the gear ratio cannot be adjusted, leading to over- or under-compression and efficiency losses when power or pressure changes
Solution Approach 1:
The single common drive wheel is segmented into two independent drive wheels, each capable of independently driving a compressor stage. This segmentation allows each stage to have its own adjustable gear ratio while maintaining a relatively simple overall structure compared to completely independent drives.
Solution Approach 2:
The gearbox incorporates adjustable gear ratios that can be changed during operation to adapt to different power levels and pressure requirements. This dynamic adjustability eliminates the fixed gear ratio limitation of conventional 3-wheel gearboxes, preventing over- or under-compression efficiency losses.
2Productivity
If the rotational speed of the first stage is changed to influence performance, then the power output is adjusted, but the second stage speed must be adjusted accordingly to maintain optimal intermediate pressure, which is difficult with fixed center distance
Solution Approach 1:
The gearbox provides dynamic speed ratio adjustment between the two compressor stages, allowing the intermediate pressure to be optimized regardless of the power output level. This dynamic control enables the system to adapt to varying operational requirements without being constrained by a fixed center distance.
3Adaptability or versatility
If the gear ratio is changed to a very small extent by modifying tooth geometry, then the structure remains similar, but the adjustment range is insufficient for significant changes in total output or final pressure
Solution Approach 1:
By segmenting the drive into two independent drive wheels with adjustable gear ratios, the system achieves a wide adjustment range for both stages. This approach provides significantly greater adaptability than minor tooth geometry modifications while maintaining manufacturing feasibility through standardized adjustable mechanisms.
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 4-wheel gearbox system enhances efficiency by minimizing thermodynamic losses, optimizing internal arrangements, and extending bearing life while reducing costs through adjustable intermediate pressures and controlled bearing forces.
Implementation Method 1
a first drive wheel (51) which engages with a first output pinion (13) and a second drive wheel (52) which engages with a second output pinion (23)
Implementation Method 2
The toothing (16, 26) between both drive gears (51, 52) and their respective output pinions (13, 23) is inclined relative to the axial extent of the drive shaft (5A)
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
The present invention relates to a drive system for a multi-stage screw compressor with a first compressor stage with a first main rotor which is mounted fixedly on a first shaft for conjoint rotation, and with a second compressor stage with a second main rotor which is mounted fixedly on a second shaft for conjoint rotation. The drive system has a drive shaft for driving the shafts of the two main rotors of the first and the second compressor stage, wherein the drive of the shaft of the first main rotor takes place independently of the drive of the shaft of the second main rotor, with the result that the rotational speeds of the two main rotors can preferably be adapted independently of one another.