Scroll Compressor Back Pressure Hole Timing
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Solution Overview
Problem
Conventional scroll compressors face issues with excessive back pressure and power consumption during low-speed operation, and compression failure due to low suction pressure, necessitating the need for a more effective back pressure control mechanism.
Innovation Solution
The scroll compressor incorporates strategically positioned and dimensioned back pressure holes that open and close within specific crank angle ranges to optimize back pressure communication between the back pressure chamber and compression chamber, reducing the duration of back pressure hole opening during low-speed operation and ensuring adequate pressure supply during low suction pressure conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If back pressure holes are opened for a long duration during low-speed operation, then back pressure chamber pressure rises, but compression chamber pressure rises excessively causing the movable scroll to be pressed against the fixed scroll and power consumption to increase
Solution Approach 1:
The back pressure holes are opened periodically rather than continuously during low-speed operation. The holes open at specific crank angle ranges (first crank angle range and second crank angle range) and remain closed during intermediate periods, creating a periodic action pattern that controls pressure buildup while reducing overall refrigerant flow into the compression chamber
Solution Approach 2:
The opening and closing of back pressure holes is made dynamic by linking it to the crank angle position. The holes open and close based on the rotational position of the scrolls, allowing the system to adapt back pressure control to the operational phase, ensuring adequate pressure during compression while limiting pressure buildup during low-speed operation
2Stress or pressure
If back pressure holes are opened continuously, then back pressure chamber pressure is maintained, but under low suction pressure conditions the compression chamber pressure becomes too low causing insufficient back pressure and compression failure
Solution Approach 1:
By opening back pressure holes periodically at specific crank angle ranges rather than continuously, the system allows compression chamber pressure to build up adequately during compression phases while still providing back pressure control when needed, preventing compression failure under low suction pressure conditions
Solution Approach 2:
The back pressure holes are positioned and timed to open in advance of the compression phase, ensuring that adequate back pressure is established before compression begins, preventing compression failure while allowing proper pressure development
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 adjusts back pressure to appropriate levels, reducing power consumption and preventing compression failure by minimizing refrigerant and oil flow into the compression chamber during low-speed operation and maintaining sufficient pressure during low suction conditions.
Implementation Method 1
a back pressure hole formed in the mirror plate of the movable scroll and communicating the back pressure chamber and the compression chamber with each other
Data Source
AI summary
A scroll compressor is provided which is capable of performing an adjustment to appropriate back pressure in both a low-speed operation condition and an operation condition low in suction pressure by improving the position or dimension of a back pressure hole. The scroll compressor includes a back pressure chamber 29 formed on the back surface of a mirror plate 31 of a movable scroll 22, and back pressure holes 51 and 52 formed in the mirror plate of the movable scroll and providing communication between the back pressure chamber and the compression chamber 34. After the back pressure hole 52 is opened inside a lap 32 of the movable scroll in a first crank angle range, the back pressure hole 52 is temporarily closed by a lap 24 of a fixed scroll 21 and then opened inside the lap of the fixed scroll in a second crank angle range.