Scroll Compressor Back Pressure Hole Layout for Wrap Rigidity
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Solution Overview
Problem
Existing scroll compressors face challenges in efficiently adjusting back pressure due to limitations in machining back pressure holes, which affect machining time, tool life, and rigidity, leading to reduced reliability and efficiency.
Innovation Solution
The scroll compressor design includes orbiting and fixed back pressure holes in the end plates, allowing adaptive pressure adjustment by covering the holes with the wrap to maintain pressure and reduce gaps, thereby enhancing reliability and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a back pressure hole is machined in the wrap to adjust back pressure chamber pressure, then the pressure can be adjusted, but the machining time increases and tool life decreases due to requiring small diameter tools
Solution Approach 1:
The back pressure hole is repositioned from the wrap surface to the end plate, changing the machining dimension from radial (requiring small diameter tools) to axial (allowing standard tools). This dimensional shift enables easier machining with conventional end mills while maintaining the back pressure adjustment function.
Solution Approach 2:
The end plate serves as an intermediary structure that facilitates back pressure hole formation. By locating the hole in the end plate rather than directly in the wrap, the design uses the end plate's thicker, more accessible material as a mediator to achieve the same functional outcome with superior manufacturability.
2Adaptability or versatility
If a back pressure hole is machined in the wrap, then pressure adjustment is possible, but the rigidity decreases due to reduced thickness between the machined part and the wrap wall
Solution Approach 1:
Moving the back pressure hole to the end plate changes the structural impact from the wrap's thin section to the end plate's thicker section. This dimensional relocation preserves the pressure adjustment function while maintaining wrap thickness and rigidity.
Solution Approach 2:
The back pressure adjustment function is segmented from the wrap structure and placed in the end plate. This separation allows the wrap to maintain its full thickness and rigidity while the end plate handles the pressure adjustment function through its own structural integrity.
3Adaptability or versatility
If a check valve is used to control back pressure chamber pressure, then pressure control is achieved, but the mechanism complexity and cost increase
Solution Approach 1:
The check valve mechanism is extracted and replaced with a passive back pressure hole design. Instead of using an active valve component, the system uses a simple hole in the end plate that passively regulates pressure through the wrap's sealing action, eliminating the need for complex valve mechanisms.
Solution Approach 2:
The design replaces expensive, complex check valves with a simple, inexpensive back pressure hole structure. The end plate hole provides sufficient pressure control without requiring costly valve components, achieving the same function at lower cost and complexity.
4Adaptability or versatility
If a pressure drop pin is provided in the back pressure hole to adjust pressure, then pressure regulation is possible, but the machining complexity and cost increase
Solution Approach 1:
The pressure drop pin is extracted from the design, eliminating the need for additional machining operations. The back pressure hole in the end plate provides sufficient pressure regulation without requiring internal pins or restrictors, simplifying the manufacturing process.
Solution Approach 2:
The pressure adjustment function is segmented from complex internal components like pins and restrictors. Instead, the design uses the simple geometry of the end plate hole and the wrap's sealing characteristics to achieve pressure regulation, reducing machining steps and component count.
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 adaptive back pressure structure improves reliability and efficiency by maintaining consistent performance across varying operating conditions, reducing machining complexity, and minimizing tool wear.
Implementation Method 1
The orbiting wrap is configured to cover at least a portion of the second end of the fixed back pressure hole based on the orbiting wrap performing the orbital motion relative to the fixed wrap
Data Source
AI summary
A scroll compressor includes an orbiting scroll that is coupled to a rotating shaft in a casing and includes an orbiting end plate portion coupled to the rotating shaft and an orbiting wrap that has a spiral shape protruding from one surface of the orbiting end plate portion, a fixed scroll including a fixed wrap that is engaged with the orbiting wrap defines a compression chamber with the orbiting wrap therebetween, and a main frame that rotatably supports the orbiting scroll and defines a back pressure chamber with the orbiting scroll. The fixed scroll defines a fixed back pressure hole having a first end configured to communicate with the first back pressure chamber and a second end is located between outer and inner circumferences of the orbiting wrap. The orbiting wrap is configured to cover at least a portion of the fixed back pressure hole during the orbital motion.