Helically Lobed Rotor Fluid Machine Friction Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing screw compressors with rolling element bearings result in large and costly fluid machines that fail to minimize friction effectively during high-speed operation, making them unsuitable for HVAC/R applications with non-flammable, low GWP refrigerants that require greater displacement.
Innovation Solution
A fluid machine design featuring a first and second rotor with helical lobes, where the second rotor has an axially-extending bore and a second shaft with a smaller diameter, allowing for lubricant circulation through an axially-extending passage to reduce friction and enable independent rotation, thereby eliminating the need for thrust bearings and simplifying alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If rolling element bearings are used to precisely position rotors and minimize friction, then rotor positioning precision and friction reduction are improved, but device size and cost increase
Solution Approach 1:
The patent removes the thrust bearing component entirely from the rotor support system. Instead of using rolling element bearings to handle both radial and axial loads, the invention uses a simplified bearing arrangement that only supports radial loads, allowing the rotor to float axially on a lubricant film.
Solution Approach 2:
The patent replaces the mechanical thrust bearing system with a hydrodynamic lubrication system. The lubricant circulation creates a pressure film that supports axial loads and enables precise rotor positioning without mechanical contact, thereby reducing friction and eliminating the need for thrust bearings.
2Loss of energy
If rolling element bearings are used to minimize friction during high speed operation, then friction reduction is improved, but device size and cost increase
Solution Approach 1:
The patent replaces mechanical contact-based friction reduction (rolling element bearings) with fluid-film-based friction reduction (hydrodynamic lubrication). The lubricant circulation system creates a continuous film between rotating and stationary components, eliminating metal-to-metal contact and significantly reducing friction during high-speed operation.
Solution Approach 2:
The patent uses a lubricant (fluid) circulation system to create hydrodynamic pressure films that support loads and reduce friction. The lubricant is pumped through passages in the rotors and distributed to bearing surfaces, creating a fluid-based friction reduction mechanism that is more efficient than mechanical bearings for this application.
3Device complexity
If thrust bearings are eliminated to simplify the fluid machine, then device complexity is reduced, but rotor alignment precision may worsen
Solution Approach 1:
The lubricant circulation system serves multiple functions simultaneously: it cools the rotors, lubricates bearing surfaces, and creates hydrodynamic pressure films that automatically position and align the rotors. The system is self-regulating, with the lubricant pressure automatically adjusting to maintain optimal rotor clearance and alignment without requiring precision mechanical alignment fixtures.
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 design achieves reduced friction, cost-effectiveness, and precise rotor positioning, balancing thrust forces, and simplifying assembly, while maintaining rigidity and reducing torque variation, noise, and vibration.
Implementation Method 1
The fluid machine may further include an axially-extending passage defined between the shaft diameter and the bore diameter, the passage circulating lubricant therethrough
Data Source
AI summary
A fluid machine includes a first rotor having a first rotor first working portion and a first rotor second working portion, a second rotor having a second rotor first working portion configured to mesh with the first rotor first working portion and a second rotor second working portion configured to mesh with the first rotor second working portion and rotate independently from the second rotor first working portion.