Rotary Compressor Vane Slot Geometry for Friction Reduction
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Solution Overview
Problem
Rotary compressors face issues with mechanical friction loss due to increased contact force between the roller and vanes, leading to reduced efficiency, refrigerant leakage, and limited design freedom, especially with oval-shaped rollers where the contact force is minimized at a 90-degree rotation angle, causing overpressure loss and machine loss.
Innovation Solution
The compressor design features a vane with a smaller rear end cross-sectional area than the front end, forming a gas accommodation portion between the vane and vane slot to control contact force, and includes a communication passage that selectively forms suction and intermediate pressures to manage the contact force between the roller and vane, reducing mechanical friction loss and preventing refrigerant leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the roller and vanes are brought into contact to form compression spaces, then the compressor can compress refrigerant, but mechanical friction loss increases due to contact force between the roller and vanes
Solution Approach 1:
A gas accommodation portion is introduced as an intermediary between the vane and vane slot. This gas-filled space acts as a mediator that reduces the contact force between the roller and vane while still allowing the compression function to operate. The gas pressure in this accommodation portion counterbalances the mechanical contact force, thereby reducing friction loss without sacrificing compression capability.
Solution Approach 2:
The cross-sectional area of the vane is varied along its length, with the rear end cross-sectional area being smaller than the front end cross-sectional area. This parameter change in the vane geometry allows for optimized pressure distribution and reduced contact force between the roller and vane, thereby reducing mechanical friction loss while maintaining compression effectiveness.
2Loss of energy
If the contact force between roller and vane is reduced to lower friction loss, then energy efficiency improves, but refrigerant leakage increases
Solution Approach 1:
The cross-sectional area of the vane is varied along its length, creating a gradient from front to rear. This parameter change allows the rear portion to maintain sufficient contact force for sealing while the overall contact force is reduced through the gas accommodation portion, thereby balancing friction reduction with leakage prevention.
Solution Approach 2:
The gas accommodation portion serves as an intermediary that modulates the contact force between roller and vane. It provides just enough gas pressure to maintain sealing contact and prevent refrigerant leakage, while avoiding excessive contact force that would cause high friction loss.
3Loss of energy
If the vane cross-sectional area is reduced to lower contact force, then mechanical friction loss decreases, but the ability to maintain contact with the roller deteriorates
Solution Approach 1:
The vane cross-sectional area is changed along its length, with the rear end having a smaller area than the front end. This gradual parameter change allows the vane to maintain adequate contact force where needed while reducing overall contact force to lower friction loss, optimizing the balance between these two requirements.
Solution Approach 2:
The gas pressure in the gas accommodation portion acts as a counterbalancing force that offsets the contact force between the roller and vane. This counterweight effect reduces the net contact force and friction loss while maintaining sufficient contact for compression and sealing functions.
4Productivity
If multiple cylinders are stacked to form multiple compression spaces, then compression capacity increases, but compressor size and material cost increase
Solution Approach 1:
Multiple compression spaces are merged into a single cylinder by using one roller with multiple vanes to create multiple compression chambers within one cylindrical housing. This combining approach achieves multi-stage compression capacity without the need for multiple separate cylinders, thereby reducing compressor size and material cost while maintaining high compression capacity.
Data Source
AI summary
A compressor is provided in which an outer circumferential side cross-sectional area of a vane slot is formed smaller than an inner circumferential side cross-sectional area thereof to decrease an area receiving a force in a roller direction by a vane to reduce a contact force between the roller and the vane, and a gas accommodation portion selectively forming a suction pressure and an intermediate pressure is formed between the vane and the vane slot to control the contact force. A contact surface of the vane facing the roller is formed at a side of a compression chamber to reduce the contact force, and a space forming a discharge pressure is formed at at least either one side of a side surface of the vane and a cylinder to decrease a side directional reaction force applied to the vane, thereby reducing a friction between the vane and the cylinder.