Freudenberg Develops High-Pressure Compressor Sealing System

The shift toward low-global-warming-potential refrigerants is forcing compressor manufacturers to redesign sealing systems for significantly higher operating pressures and stricter reliability requirements. In this context, Freudenberg Sealing Technologies introduced a new elastomer-based sealing system for busbar feedthroughs in vehicle air-conditioning compressors using CO2 refrigerant technology.

Sealing challenges in CO2 compressor systems
European regulations targeting fluorinated greenhouse gases are accelerating the transition away from refrigerants such as R134a and R1234yf toward alternatives including R744 (CO2) and R290 (propane). While CO2 refrigerant systems offer environmental advantages, they also operate at substantially higher pressures than conventional automotive air-conditioning compressors.

One of the main engineering challenges involves sealing electrical feedthroughs such as busbars and pins within compressor housings. CO2 molecules are significantly smaller than many conventional refrigerant molecules and can permeate elastomer materials under high-pressure conditions.

During rapid pressure changes, trapped gas molecules may expand inside the sealing material, potentially causing internal structural damage through explosive decompression. In addition to pressure resistance, the seals must also withstand electrical and mechanical stresses inside compact compressor assemblies.

Material design tailored for R744 applications
Freudenberg Sealing Technologies developed the new sealing system using elastomer materials engineered specifically for high-pressure CO2 compressor environments. The material formulation was designed to resist explosive decompression while maintaining chemical resistance against conventional refrigerants and alternative cooling media.

The company also incorporated elastomer variants with high comparative tracking index (CTI) characteristics to reduce the risk of creep currents and electrical arcing at busbar feedthrough locations.

The sealing contour was developed using an integrated design process intended to align manufacturability, sealing geometry, and functional safety requirements. Freudenberg stated that the sealing system withstood leak-test pressures exceeding 100 bar during validation testing.

The sealing solution was developed as an alternative to glass-based sealing systems commonly used in compressor feedthrough applications. According to the company, the elastomer-based approach can reduce sealing costs per busbar or pin by up to 30 percent depending on application requirements. Because compressors typically contain three busbars, the reduction can affect overall compressor manufacturing costs.

Compact integration and broader refrigerant compatibility
The sealing system was also designed to support compact compressor layouts where installation space is limited. Freudenberg stated that the material portfolio used in the solution supports operating temperatures ranging from -40 degrees Celsius to above 200 degrees Celsius while maintaining compatibility with multiple refrigerants.

The company indicated that the technology can be adapted to compressor-specific geometries, sealing contours, and manufacturing requirements with shorter development cycles and series-production compatibility.

Freudenberg Sealing Technologies stated that prototype systems have already undergone validation testing and that the company is working on development projects with multiple vehicle compressor manufacturers. Although initially developed for R744 compressor systems, the sealing technology is also intended for other high-pressure applications involving different operating media.

Edited by Aishwarya Mambet, Induportals Editor, with AI assistance.

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