Dry-compressing Vacuum Pump Toothed Belt Synchronization
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Solution Overview
Problem
Existing dry-compressing vacuum pumps, such as screw pumps, face high costs and complexity due to the need for precise synchronization and oil lubrication, which is challenging with meshing gears or toothed belts, especially when achieving low vacuum pressures.
Innovation Solution
A dry-compressing vacuum pump design using a toothed belt for driving and synchronizing rotor shafts with a large torsional backlash, combined with multiple displacement elements of varying pitches and profiles, eliminates the need for oil lubrication and reduces production costs by allowing for a simpler seal configuration and increased service life of components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If meshing gears are used for synchronization, then precise synchronization (±0.25°) is achieved, but manufacturing costs increase due to tight tolerances
Solution Approach 1:
The patent changes the synchronization parameter from tight angular tolerances (±0.25°) to a belt-based system with larger permissible backlash (>±0.75°), allowing standard manufacturing tolerances while maintaining functional synchronization through the belt's flexibility and engagement mechanism
Solution Approach 2:
The patent replaces the direct mechanical meshing gear system with a belt-driven system, substituting the rigid tooth-to-tooth engagement with a flexible belt that can accommodate larger tolerances while still providing positive engagement through its teeth
2Manufacturing precision
If meshing gears are used for synchronization, then precise synchronization is achieved, but device complexity increases due to oil lubrication requirements and complex seals
Solution Approach 1:
The patent extracts the lubrication requirement from the synchronization system by using a dry-running belt drive, eliminating the need for oil lubrication and the associated complex sealing arrangements while maintaining synchronization functionality
Solution Approach 2:
The patent employs a simpler belt and pulley system that can operate without lubrication, using components that are inherently simpler and less complex than gear systems, accepting that the belt may have a limited service life but gaining significant simplicity in the overall system
3Manufacturing precision
If toothed belts are used with small backlash (<0.2mm) to achieve high vacuum, then synchronization precision improves, but service life of the belt decreases significantly
Solution Approach 1:
The patent changes the backlash parameter from small values (<0.2mm) to large values (>0.75° torsional backlash), which reduces the stress and wear on the belt while still achieving functional synchronization, thereby extending belt service life
Solution Approach 2:
The patent employs a dynamic belt-tensioning system with spring-loaded adjustment that maintains optimal engagement between the belt and pulleys throughout the belt's service life, accommodating wear and tension changes while preserving synchronization accuracy
4Manufacturing precision
If larger effective diameter pulleys are used to reduce pitch error, then synchronization precision improves, but belt service life decreases due to forced pitch error
Solution Approach 1:
The patent changes the approach by accepting large backlash values instead of increasing pulley diameter, thereby avoiding the forced pitch error that would result from large-diameter pulleys and their associated manufacturing tolerances
Data Source
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AI summary
A dry-compressing vacuum pump, in particular a screw pump, has two rotor elements (14) which are arranged in a pump chamber (12) and which are each carried by a rotor shaft (22). Two shaft ends of the rotor shafts (22) project through a side wall (28) of the pump housing (10). On the two shaft ends (28) there is arranged in each case one toothed belt pulley (38). Furthermore, a drive device and an electric motor for driving the rotor shaft (22) are provided. According to the invention, the rotor shafts (22) are driven by means of a toothed belt (40). To be able to use a toothed belt for drive purposes, a rotational flank clearance between the two rotor elements (14) of greater than ±0.75°, in particular greater than ±1°, is provided.