Scroll Compressor Eccentric Crank Pin Seals

Industrial scroll compressors are widely used for compressing air or refrigerant in heating, ventilation, air conditioning and refrigeration systems. They are known for their high efficiency, reliability, and quieter operation compared to traditional reciprocating compressors. As a type of positive-displacement compressor that works through the internal compression of air or gas, ensuring a tight seal at various dynamic points is critical for optimal performance. One such critical point is the eccentric crank pin where rotary lip seals are often used. The crank pin serves as the pivot for the orbiting scroll, which continuously compresses the media. When the crank pin is eccentric, sealing control around this component becomes more complex and challenging.

During long-term operational use, compressor manufacturers observed premature lip seal wear. This wear led to decreased system efficiency, shorter service intervals, increased cost,  and potential compressor damage. Specifically, the eccentric crank pin was found to be a critical area where leaks occurred due to inadequate sealing.

Using our many years of knowledge from collaborating with scroll compressor partners, Omniseal Solutions’ engineering and technical teams conducted an extensive review to solve the crank pin sealing problem. The following steps were quickly taken to address the sealing and wear issues:

• Advanced Material Selection: The global team explored various lip sealing materials with high performance properties: superior wear resistance, thermal stability, and low friction characteristics. A new type of lip seal material was selected, offering higher flexibility versus traditional lip seal materials.
• Seal Design Improvements: A precision seal using a “FEA design, testing, feedback loop approach” was developed to reduce validation costs. The improved seal design increased dry running capabilities as well as optimized lip length and lip load that minimized the risk of leakage due to wear or misalignment.
• Rigorous Testing & Prototyping: Multiple prototypes of the new lip sealing system were created with our internal, controlled laboratory conditions. Leak tests were conducted to ensure that the new rotary lip seal provided a tight and durable seal at the crank pin location. Seal longevity was accurately evaluated by running the scroll compressors through durability cycles and real-world field operating conditions.

As a result of this thorough design and testing processes, our custom Omniseal^® rotary lip seals solved premature wear, providing a longer-term solution that saves our industrial customer cost and time.

• Lower wear
• Extended service intervals
• Lower seal cost due to simplified design