Reductions in particulate matter and nitrogen oxide emissions have become a global challenge that no truck or bus manufacturer can avoid. With its Low Emission Sealing Solutions (LESS), Freudenberg-NOK Sealing Technologies is offering an answer to the demands for greater fuel savings, lower emissions, reduced maintenance costs and a longer operating life – even under harsh environmental conditions. From Sept. 25 – Oct. 2, the industry is taking a look at the demands on commercial vehicle manufacturers at the 65th IAA Commercial Vehicles show in Hannover, Germany.
Robustness under high pressures
The increasingly stringent emissions limits for engines in the automotive field are requiring new technical solutions – covering everything from fuel injection to exhaust after-treatment. Pump plungers in today’s high-pressure injection pumps, for example, operate with a frequency of more than 200 Hz. This requires a seal that is extremely wear-and heat-resistant. In addition, it deals with pressures that are significantly higher than those in intake systems.
The new double-action PTFE grooved ring Duo Forseal from Freudenberg-NOK Sealing Technologies can handle the load – even after more than 1 billion strokes – and offers all the technological characteristics of the current model lines. This includes universal resistance to all kinds of motor oils and fuels, including E100, along with easy assembly due to a symmetrical seal arrangement. Thanks to its reduced leakage rates, the Duo Forseal also makes a direct contribution to emissions reduction.
The BlueSeal seal ring from Freudenberg is also designed for use in high-pressure pumps. This patented technology weighs 25 percent less than a conventional seal and requires only half as much installation space. Due to its additional metal carrier, the BlueSeal seal ring is mechanically resistant to high pressures and resists aggressive substances due to the PTFE material in its seal lip. The low friction associated with the PTFE material also reduces shaft wear and the temperature in the contact area.
Low friction saves fuel
The use of seals in axle and wheel hubs in trucks and trailers also capitalizes on the advantages of friction reduction. The new MileMaker cassette seal rings from Freudenberg-NOK Sealing Technologies are made from an advanced elastomer developed by the company. It reduces friction and seal-related torque losses by 50 percent compared to competitors’ seals. Over the seals’ entire lifespan, this leads to average fuel savings of 1000 liters per truck-trailer combination. Cassette sealing rings protect the hubs from the penetration of dirt and moisture. The elastomer material developed for MileMaker seals stands up to high operating temperatures of up to 177 °C and resists mineral and synthetic oils and lubricating grease.
The CASCO cassette seal at the crankshaft output in commercial vehicles protects against soiling and extreme environmental influences with its axially positioned seal lip. It is the ideal combination of outstanding sealing qualities, optimized friction and maximum durability. A test over an operating span of 1.6 million kilometers clearly demonstrated a number of positive outcomes: Its 60 percent reduction in friction lowers fuel consumption on a ongoing basis, compared to a conventional PTFE or spring-loaded seal lip, and reduces oil carbon buildup significantly. Furthermore, it reliably prevented oil leakage.
Counter-pressure seal lip reduces oil use and emissions
Counter-pressure valve stem sealing is one of the numerous innovations from Freudenberg-NOK Sealing Technologies for the exhaust area. The new generation of turbocharged engines build up such a high exhaust counter-pressure that the seal lip of conventional valve shaft seals can lift up. As a result, combustion gases are forced into the valve stem guide, which can lead to a tear in the lubricating film. The consequences are higher oil use and rising emission values, along with an impairment of the particulate filter. Counter-pressure valve stem seals do not merely have a secondary lip that increases seal lift from between 1.5 to 4 bar to between 4.5 and 5 bar; an additional counter-pressure lip also reliably prevents a seal failure up to a pressure differential range of much more than 6 bar.