Oil-Free Screw Compressor Seal Layout for Shorter Bearing Distance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional oil-free screw compressors are complex in configuration, making them difficult to manufacture, and the long distance between communication sections leads to potential bending of the screw rotor, reducing volumetric efficiency.
Innovation Solution
The oil-free screw compressor simplifies its casing configuration by using a single atmosphere communication section for both shaft seal devices, reducing the distance between the screw rotor and bearings, and incorporating a larger flow passage sectional area in the first communication section to prevent negative pressure and lubricating oil intrusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two separate atmosphere communication sections are formed in the casing for the first and second shaft seal devices, then the shaft seals can communicate with the atmosphere independently, but the device complexity increases and manufacturing becomes difficult
Solution Approach 1:
The patent merges the atmosphere communication function for both the first and second shaft seal devices into a single shared atmosphere communication section in the casing. This eliminates the need for two separate communication sections, thereby reducing structural complexity and manufacturing difficulty while maintaining the atmospheric communication capability for both seals.
Solution Approach 2:
The single atmosphere communication section serves multiple functions by providing atmospheric communication for both the first shaft seal device and the second shaft seal device simultaneously. This multi-functional design reduces the number of components needed in the casing structure.
2Ease of manufacture
If the first and second communication sections are positioned far apart in the extension direction of the rotation center line to avoid interference, then the atmosphere communication sections can be properly disposed, but the distance between the screw rotor and bearing increases causing potential rotor bending
Solution Approach 1:
The patent positions the first and second communication sections at different angular positions around the rotation center line rather than spacing them far apart in the extension direction. This dimensional change from linear spacing to angular positioning allows the communication sections to be close in the extension direction while avoiding interference, thereby maintaining short bearing distances and rotor stability.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The oil-free screw compressor 10 includes: a screw rotor 14 including a screw 14a and a shaft 14c; a bearing 26; a first shaft seal device 30 disposed between the screw and the bearing, the first shaft seal device including: a first seal 38a and a first communication section 30a configured to communicate the bearing side with respect to between the shaft and the first seal, and an outer peripheral face of the first shaft seal device; a second shaft seal device 32 disposed between the first shaft seal device and the bearing, the second shaft seal device including: a second seal 32a and a second communication section 32c configured to communicate the screw side with respect to between the shaft and the second seal, and an outer peripheral face of the second shaft seal device; and a first seal member 50 including a seal between the first communication section and the second communication section. The casing 12 includes an atmosphere communication section 12m configured to communicate the first communication section and the second communication section with an atmosphere. A sectional area in the first communication section is larger than a sectional area between the seal of the first seal member and the shaft.