Scroll Compressor Wrap Geometry Reduces Over-Compression Loss
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Solution Overview
Problem
In scroll compressors, over-compression loss increases due to the pressure of fluid exceeding discharge pressure during the discharge phase, particularly with higher speed operations, leading to inefficiencies and increased size requirements when attempting to extend the fluid compression passage.
Innovation Solution
The design incorporates a rate-reduced compression chamber with a modified involute curve shape for the wraps of the fixed and orbiting scrolls, reducing the volume change rate during the compression phase, which minimizes over-compression by adjusting the base circle radius in a stepwise manner and ensuring the volume change rate is reduced before the discharge phase begins, thus preventing excessive fluid compression.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the number of turns of the wrap is increased to extend the fluid compression passage, then the over-compression loss is reduced, but the size of the scroll compressor is increased
Solution Approach 1:
The invention applies different geometric properties to different sections of the wrap. Specifically, the wrap is designed with a varying curvature radius where the curvature radius at the inner end is smaller than that at the outer end. This local variation in geometric quality allows the compression passage to be extended effectively without proportionally increasing the overall compressor size, thereby reducing over-compression loss while controlling the device footprint.
Solution Approach 2:
The invention transitions from a uniform wrap geometry to a non-uniform wrap geometry by varying the curvature radius along the wrap length. This dimensional change in the geometric parameters allows the compression passage to follow a more efficient path, extending the effective compression distance without simply increasing the number of turns or the overall size of the compressor housing.
2Loss of energy
If the volume change rate is reduced in the middle of compression phase, then over-compression is minimized, but the compression mechanism complexity increases
Solution Approach 1:
The invention changes the geometric parameter of the wrap, specifically the curvature radius, to control the volume change rate during compression. By designing the wrap with a curvature radius that varies along its length (smaller at the inner end, larger at the outer end), the system achieves a reduced volume change rate in the middle of the compression phase. This parameter change approach allows control over compression characteristics without adding mechanical complexity such as variable geometry mechanisms or control systems.
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
This configuration effectively reduces over-compression loss without increasing the size of the scroll compressor, ensuring efficient operation and maintaining a desired compression ratio while minimizing over-compression occurrences.
Implementation Method 1
The orbiting scroll (36) eccentrically rotates, without turning on an axis thereof, with respect to the fixed scroll (31) to compress fluid in compression chambers (41A, 41B) respectively formed inside and outside the wrap (38) of the orbiting scroll (36)
Data Source
AI summary
A scroll compressor includes a fixed scroll and an orbiting scroll. Each of the fixed and orbiting scrolls includes an end plate and a spiral wrap standing on a front surface of the end plate. The scrolls are arranged such that the front surfaces of the end plates face each other and the wraps are engaged with each other. The orbiting scroll eccentrically rotates, without turning on an axis thereof, with respect to the fixed scroll to compress fluid in compression chambers respectively formed inside and outside the wrap of the orbiting scroll. Each wrap is formed in a shape such that at least one of the compression chambers serves as a rate-reduced compression chamber where a volume change rate thereof is reduced in a middle of a compression phase.