Rotary Compressor Asymmetric Suction Passage Design
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Solution Overview
Problem
Downsizing a 2-cylinder rotary compressor while maintaining compressor efficiency is challenging due to increased suction resistance when connecting two suction pipes to a single accumulator, leading to efficiency deterioration.
Innovation Solution
The compressor features a unique suction passage configuration with a first passage supplying the first cylinder and a second passage branching from the first passage to supply the second cylinder, where the surface area facing the suction passage in the second cylinder is smaller than in the first, reducing temperature differences and minimizing piston-cylinder dimensional changes, thus reducing oil leakage and improving efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If two suction pipes are connected to the accumulator, then each cylinder can receive refrigerant independently, but the accumulator cannot be downsized
Solution Approach 1:
The patent merges the suction pipe connections by having both the first and second cylinders connect to the accumulator through a single suction pipe rather than two separate pipes. This consolidation reduces the accumulator size while maintaining refrigerant supply to both cylinders through a unified connection path.
2Volume of moving object
If a single suction pipe is used to connect both cylinders to the accumulator, then the accumulator can be downsized, but suction resistance increases and compressor efficiency deteriorates
Solution Approach 1:
The patent applies local quality by creating an asymmetric suction passage configuration where the first cylinder has a larger surface area facing the suction passage than the second cylinder. This localized variation in surface area distribution optimizes refrigerant flow characteristics and reduces suction resistance in specific regions, compensating for the unified single-pipe connection.
Solution Approach 2:
The patent changes geometric parameters by adjusting the surface areas of the cylinders facing the suction passage. Specifically, the first cylinder is designed with a larger surface area than the second cylinder, creating a parameter difference that influences refrigerant flow distribution and reduces overall suction resistance despite using a single suction pipe.
3Reliability
If the surface area facing the suction passage is made smaller in the second cylinder, then temperature difference decreases and oil leakage is reduced, but the cylinder design becomes more complex
Solution Approach 1:
The patent implements asymmetry by designing the second cylinder with a smaller surface area facing the suction passage compared to the first cylinder. This asymmetric configuration creates different thermal characteristics in each cylinder, reducing temperature differences that cause piston-cylinder dimensional changes and subsequently minimizing oil leakage risks.
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 enhances volume and indicated efficiency, compensating for the increased suction resistance and achieving both downsizing and efficiency suppression, thereby maintaining compressor performance.
Implementation Method 1
a difference between the height of the second cylinder in the axial direction and the height in the axial direction of the piston provided in the compression chamber of the second cylinder is smaller than a difference between the height of the first cylinder in the axial direction and the height in the axial direction of the piston provided in the compression chamber of the first cylinder
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
In a rotary compressor including first and second cylinders aligned in the axial direction of a drive shaft, a suction passage is formed to supply refrigerant supplied from an external device via a suction pipe to each compression chamber. The surface area of a region facing the suction passage in the second cylinder is smaller than the surface area of a region facing the suction passage in the first cylinder. A difference between the height of the second cylinder in the axial direction and the height of a piston provided in the compression chamber of the second cylinder is smaller than a difference between the height of the first cylinder in the axial direction and the height in the axial direction of a piston provided in the compression chamber of the first cylinder (A3-A4<A1-A2). With this arrangement, downsizing of the compressor and suppression of decrease in compressor efficiency are both achieved.