Latest sealing technologies address fuel economy, light weighting, start-stop and electrification

The ability of sealing solutions to improve fuel economy and reduce emissions is coming into focus as automakers seek strategies beyond lightweighting to meet legislated targets. Freudenberg Sealing Technologies (Plymouth, MI) recently outlined its Low Emission Sealing Solutions (LESS) initiative that aims to address multiple transportation industry challenges.

One such product is a gas-lubricated mechanical face seal called Levitex, which is under development and due for introduction in 2017. The seal is made from high strength automotive steels and proprietary Freudenberg high performance elastomers.

Essentially friction-free, a cushion of air is created between the slide ring and a counter ring, leading to a 90 percent reduction in friction compared to a conventional crankshaft seal. This reportedly cuts CO₂ emissions during driving by between 0.5 g and 1.0 g of per kilometer. A 1.0 g reduction in CO₂ emissions is the equivalent of approximately 0.2 mpg savings in gas for a vehicle rated at a 33 mpg. The seal also facilitates longer operation by reducing wear.

The company's Energy Saving Seal (ESS), for engine crankshafts and camshafts as well as transmissions, combines the robust sealing interface of a conventional polytetrafluoroethylene (PTFE) collar with the friction-reducing properties of an elastomer seal. Friction is reduced by 40 percent compared with a conventional PTFE lip.

Casco cassette-type seals, meanwhile, reportedly offer up to 70% greater energy savings compared with conventional lip designs used in other engine seals. The Casco cassette-type seal generates a much lower friction due to the advanced design of its "axial" sealing lip. Casco seals performed and successfully passed several bench tests reaching over 1 million miles. Customer field tests confirmed this performance. These seals are also made from a combination of high strength automotive steels and proprietary Freudenberg high performance elastomers.

Freudenberg can also offer a multi-pole encoder that can be combined with a radial shaft seal, creating one component. The elastomer layer, which can be magnetized and encoded with north and south poles, provides the engine control module with precise information on the rotational speed and the position of the crankshaft - an important criterion for start-stop systems. This makes it possible to minimize installation space, weight and process costs.

The company is also working on many innovations in the area of lightweight construction. For example, hydraulic accumulators are saving energy and weight in transmissions. Automatic start-stop systems require high volume flow for short periods. A hydraulic accumulator with a lightweight design covers peak pressure in the short term. This means the hydraulic system can be designed solely for average energy needs, and the drive train can be made smaller and lighter.

Freudenberg has been able to build its expertise in the area of lightweight construction through its joint venture with the Schneegans Group. This partnership has allowed the company to leverage Schneegans' expertise in two- and multi-component injection molding. Examples of this technology include the 3D-form full-plastic tubes for oil dip sticks and oil filler necks. These components allow the tight space in the engine compartment to be optimally used.

In the case of 2K plastic pump housings, seals can be injected directly for oil and water circuits for added functional security. The same is true for housings with seals integrated into their covers with a 2K design; they absorb dynamic stresses and can provide tolerance compensation even during significant temperature swings. A wide range of resins are used in these applications, which include control module housings, door lock systems, and electronic anti-lock brake systems.

Freudenberg-NOK is also making a contribution to innovative solutions in electric mobility via its radial shaft seal or Simmerring seal technology. The input shaft in an electrically powered vehicle's axle drive can become electrically charged, potentially damaging the transmission. A Simmerring with an electrically conductive PTFE-graphite nonwoven material grounds the electrical charge from the shaft to the housing, effectively eliminating the threat of damage.