CO2 Scroll Compressor Injection Port Sizing for Tip Seal Protection
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Solution Overview
Problem
The use of carbon dioxide as a refrigerant in scroll compressors leads to high operating pressure and discharge temperature, causing a significant pressure difference that results in the breakage of tip seal members due to the tip seal member entering the injection ports during the eccentric revolving motion of the orbiting scroll.
Innovation Solution
The scroll compressor design includes injection ports with a diameter φinj ≤ 0.95 × TIP, where TIP is the width of the tip seal member in a direction perpendicular to the spiral direction, to prevent the breakage of the tip seal member by controlling the pressure difference and ensuring reliable operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If carbon dioxide is used as refrigerant, then refrigerant efficiency is improved, but discharge temperature increases and pressure difference becomes large causing tip seal member breakage
Solution Approach 1:
The invention changes the geometric parameters of the injection port (diameter, shape) to optimize the balance between refrigerant injection effectiveness and tip seal member protection. By adjusting the injection port diameter to be smaller than the tip seal member width, the system maintains efficient heat exchange while preventing seal breakage under high pressure differential conditions with CO2 refrigerant
Solution Approach 2:
The invention applies preliminary protective design by making the injection port smaller than the tip seal member before the breakage problem occurs. This preventive geometric configuration ensures that even when the orbiting scroll passes over the injection port during operation, the tip seal member cannot enter or break through the injection port, thus preventing breakage before it happens
2Quantity of substance
If injection port diameter is increased, then refrigerant injection amount is improved, but tip seal member breakage risk increases
Solution Approach 1:
The invention optimizes the injection port diameter parameter to a specific range that balances refrigerant injection quantity with tip seal member protection. The diameter is set large enough to provide sufficient cooling effect but small enough to prevent the tip seal member from breaking through during orbiting scroll motion
3Device complexity
If tip seal member width is decreased, then device complexity is reduced, but sealability deteriorates under high pressure
Solution Approach 1:
The invention determines an appropriate tip seal member width that provides sufficient sealing capability under high CO2 pressure while maintaining reasonable device simplicity. The width is optimized to be larger than the injection port diameter to prevent breakage while not being excessively large to avoid unnecessary 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 design effectively prevents the breakage of the tip seal member and improves the reliability of the scroll compressor by maintaining the integrity of the seal, even under high pressure conditions with carbon dioxide as the refrigerant.
Implementation Method 1
a tip seal member that is inserted in the tip of the scroll wrap of the orbiting scroll along the spiral direction and that is in sliding contact with the baseplate of the fixed scroll
Implementation Method 2
By causing liquid refrigerant to flow through the injection ports into compression chambers at an intermediate pressure, the gas temperature in the compression chambers is lowered, the temperature of refrigerant discharged from the compression chambers
Implementation Method 3
a crankshaft that causes the orbiting scroll to perform eccentric revolving motion
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
A scroll compressor includes a shell 8, a fixed scroll 1 and an orbiting scroll 2 disposed in the shell 8, a first scroll wrap 1b and a second scroll wrap 2b that are provided in the fixed scroll 1 and the orbiting scroll 2, respectively, and that are engaged with each other to form a plurality of compression chambers 9, a crankshaft 4 that causes the orbiting scroll 2 to perform eccentric revolving motion, a tip seal member 17b that is inserted in the tip of the second scroll wrap 2b along the spiral direction and that is in sliding contact with the first baseplate 1c of the fixed scroll 1, and injection ports 16 that are provided through the first baseplate 1c of the fixed scroll 1 and that introduce refrigerant at an intermediate pressure between suction pressure and discharge pressure into the compression chambers 9 from the outside of the shell 8. The refrigerant is composed only of carbon dioxide or is a mixed refrigerant containing carbon dioxide. The diameter φinj of the injection ports 16 and the width TIP of the tip seal member 17b in a direction perpendicular to the spiral direction have the relationship of φinj ≤ 0.95 × TIP.