Scroll Compressor Back-Pressure Chamber Design
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Solution Overview
Problem
The existing scroll compressors in on-vehicle air conditioners face inefficiencies due to refrigerant gas leakage through chip clearance, limited by the area of the back-pressure chamber, which restricts the pressing force on the rotational scroll, leading to reduced compression efficiency and increased activation torque and noise.
Innovation Solution
The design enhances the area of the back-pressure chamber by eliminating the need for a seal ring groove on the thrust surface, allowing the outer seal ring to be pressed between the housing and the thrust plate, thereby increasing the chamber's width and area, and utilizing a triangular seal structure to maximize the back-pressure's pressing force on the rotational scroll, reducing leakage and noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the area of the back-pressure chamber is increased to enhance pressing force on the rotational scroll, then compression efficiency is improved, but the interval between the inner seal ring and outer seal ring must be increased, which is limited by the seal ring groove on the thrust surface
Solution Approach 1:
The patent relocates the outer seal ring from the thrust surface to the outer peripheral surface of the thrust plate, changing the sealing dimension from the axial direction to the radial direction. This dimensional shift allows the back-pressure chamber area to be increased without being constrained by the seal ring groove on the thrust surface, thereby resolving the contradiction between chamber area and seal ring interval limitations.
2Area of stationary object
If the diameter of the O-ring inner seal ring is reduced and the diameter of the outer seal ring is increased to increase the interval between them, then the back-pressure chamber area is increased, but the outer seal ring requires a larger radial space that may not be available
Solution Approach 1:
The outer seal ring is repositioned from the axial dimension (thrust surface) to the radial dimension (outer peripheral surface), utilizing previously unused radial space. This allows the back-pressure chamber to expand in the axial direction without increasing radial space requirements, effectively resolving the spatial constraint contradiction.
3Loss of energy
If a larger back-pressure chamber is formed to press the rotational scroll more effectively, then refrigerant gas leakage through chip clearance is reduced, but the housing structure becomes more complex
Solution Approach 1:
The outer peripheral surface of the thrust plate serves dual functions: supporting the load in the thrust direction and providing a mounting surface for the outer seal ring. This multi-functionality eliminates the need for additional housing structures or seal ring grooves, allowing the back-pressure chamber to be enlarged without increasing device complexity.
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 increases the pressing force on the rotational scroll, reducing refrigerant gas leakage, lowering activation torque, and minimizing activation noise by ensuring consistent contact between the scrolls, thereby improving compression efficiency and reducing noise.
Implementation Method 1
part of the refrigerant gas compressed in the compression pocket is extracted and supplied to a back-pressure chamber formed on a thrust surface facing a back side of the thrust plate as back pressure
Implementation Method 2
pressing force on the rotational scroll due to back pressure is enhanced
Implementation Method 3
The outer seal ring is provided to be pressed between an inner peripheral surface of the housing and an outer peripheral surface of the thrust plate
Data Source
AI summary
The area of a back-pressure chamber is increased so that pressing force on a rotational scroll due to back pressure is enhanced to reduce leakage of refrigerant gas through a chip clearance, thereby achieving improved compression efficiency.A scroll compression mechanism configured to form a compression pocket between a fixed scroll and a rotational scroll 10 facing each other and including a thrust plate 12 configured to support a thrust load of the rotational scroll 10, and a back-pressure supplying mechanism 6 configured to supply part of compressed refrigerant gas to a back side of the thrust plate 12 as back pressure are provided. The back-pressure supplying mechanism 6 includes a back-pressure chamber 31 formed on a thrust surface 30 facing the back side of the thrust plate 12, a back-pressure supplying path 32 through which the compressed refrigerant gas is supplied to the back-pressure chamber 31, and an inner seal ring 33 and an outer seal ring 34 disposed radially inside and outside, respectively, of the back-pressure chamber 31. The outer seal ring 34 is provided to be pressed between an inner peripheral surface 37 of a housing 2a and an outer peripheral surface 12a of the thrust plate 12.