Freudenberg develops sealing system for high-pressure CO2 compressors

Weinheim, Germany — Freudenberg Sealing Technologies (FST) has developed a new elastomer-based sealing system for electrical feedthroughs in vehicle air-conditioning compressors designed for high-pressure CO2 refrigerants, as automakers transition away from fluorinated gases.

In a 7 May statement, the supplier said the sealing solution was developed for compressors using ‘R744 (CO2) refrigerant,’ which operates at significantly higher pressures than conventional systems using fluorinated refrigerants such as R134a and R1234yf.

According to FST, the new system is designed to seal busbars or pins in compressor housings and withstand the challenges posed by “tiny CO2 molecules” and elevated operating pressures.

Conventional elastomer seals, it noted, can suffer from “explosive decompression,” where gas molecules penetrate the material and expand rapidly during sudden pressure drops, damaging the seal internally.

To address this, FST said it “specifically developed [elastomer] for use in CO2 compressors that resist explosive decompression and offer high media resistance to conventional refrigerants.”

This, it added, also involved using elastomer variants that offer “a high comparative tracking index (CTI),” thus reliably preventing creep currents from arcing at the busbar feedthrough.

The supplier said the sealing contour was developed using an “integrated development approach” combining manufacturability, component design and functional safety.

FST said the system withstood test pressures of more than 100 bar in leak tests.

“With this change in refrigerants, manufacturers of air-conditioning compressors are facing entirely new sealing requirements,” said Christian Jaschke, product manager at FST.

FST, Jaschke said, offers a development partnership “from the material selection to a sealing contour that is ready for series production,” to manufacturers.
According to FST, the elastomer-based system could provide a lower-cost alternative to conventional glass seals, reducing sealing costs by up to 30% per busbar or pin depending on the application.

The company added that the compact design could also help optimise installation space in compressor systems.

Freudenberg said the technology can be adapted for use with refrigerants other than CO2 and for other high-pressure applications.

According to the supplier, development projects are currently underway with “several vehicle compressor manufacturers,” with initial prototypes already validated.