Scroll Compressor Back Pressure Control Valve Segmentation
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Solution Overview
Problem
Modulation scroll compressors face challenges in adjusting back pressure properly across operation modes, leading to reliability issues, increased friction loss, and manufacturing complexities due to difficulties in sealing and assembly, especially when varying the compression capacity.
Innovation Solution
A scroll compressor with a capacity variable device that includes a back pressure control valve and capacity control valve, allowing for independent control of back pressure by communicating with multiple intermediate pressure chambers, thereby adjusting discharge pressure based on operation mode to maintain optimal sealing and reduce manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If the back pressure hole is moved closer to the discharge port to increase back pressure in power operation, then the back pressure increases, but friction loss between scrolls increases and reliability deteriorates
Solution Approach 1:
The back pressure control is segmented into multiple independent back pressure holes (first back pressure hole and second back pressure hole) positioned at different locations. This allows selective opening of specific holes to achieve different back pressure levels for different operation modes, resolving the contradiction between needing high back pressure for power operation and low friction loss for efficiency.
Solution Approach 2:
The back pressure holes are dynamically controlled through a back pressure control valve that selectively opens or closes specific holes based on operation mode. This dynamic control allows the system to adapt back pressure levels to operational requirements, maintaining optimal back pressure in power operation while reducing friction loss through proper pressure management.
2Stress or pressure
If the back pressure hole is moved closer to the suction port to decrease back pressure in saving operation, then the back pressure decreases, but discharge pressure is reduced and clearance is generated causing noise and refrigerant leakage
Solution Approach 1:
Multiple back pressure holes are positioned at different locations (first hole closer to discharge port, second hole closer to suction port) to provide different back pressure control options. This segmentation enables selective use of holes to maintain proper back pressure and sealing in saving operation while allowing capacity reduction through the bypass hole.
Solution Approach 2:
The back pressure control valve dynamically selects which back pressure hole to open based on operation mode. In saving operation, the valve opens the second back pressure hole to maintain adequate back pressure and sealing while allowing the bypass hole to reduce capacity, preventing noise and refrigerant leakage.
3Adaptability or versatility
If the capacity variable device is provided outside the casing, then capacity control is achieved, but the number of parts and assembly processes increases and sealing becomes difficult
Solution Approach 1:
The back pressure control valve and capacity control valve are merged into a single integrated valve body with multiple ports and internal passages. This integration reduces the number of separate parts, simplifies assembly, and eliminates external connections while maintaining full capacity control functionality through internal bypass passages.
Solution Approach 2:
The integrated valve body performs multiple functions: it controls back pressure through selectable back pressure holes, controls capacity through the bypass hole, and manages refrigerant flow through internal passages. This multi-functionality eliminates the need for separate external devices, reducing part count and assembly complexity.
4Device complexity
If a single intermediate pressure is used to adjust back pressure, then the structure is simple, but proper back pressure adjustment across different operation modes is difficult
Solution Approach 1:
The single intermediate pressure system is segmented into multiple back pressure holes that can be selectively opened. Each hole provides a different back pressure level, enabling the system to adapt to different operation modes (power operation requiring high back pressure, saving operation requiring lower back pressure) while maintaining a relatively simple structural framework.
Data Source
AI summary
A scroll compressor may include an orbiting scroll; a non-orbiting scroll engaged with the orbiting scroll to form a pair of compression chambers between the orbiting scroll and the non-orbiting scroll; a back pressure chamber assembly coupled to the non-orbiting scroll to form a back pressure chamber to support the non-orbiting scroll toward the orbiting scroll; a first back pressure passage that connects a first intermediate pressure chamber in the compression chamber and the back pressure chamber; a second back pressure passage that connects a second intermediate pressure chamber having a higher pressure than the first intermediate pressure chamber and the back pressure chamber; and a back pressure control valve configured to selectively open and close the first back pressure passage and the second back pressure passage according to an operation mode. The back pressure control valve moves to a first position at which the first back pressure passage is open and the second back pressure passage is closed in a power operation, and moves to a second position at which the first back pressure passage is closed and the second back pressure passage is open in a saving operation.