The automotive industry makes particularly exacting demands on its suppliers. Constant pressures to innovate, for instance due to new legal requirements and changing customer wishes paired with the highest quality requirements and high cost pressures, result in a challenging field in which Parker Prädifa has been successfully operating for decades.
Numerous Parker products have proven their viability in practically all production vehicles around the globe in a great diversity of applications ranging from fuel tanks to sun roofs.
The fuel system supplies the “heart” of the vehicle, the engine, with energy. The system extends across nearly the whole vehicle from the filler neck to the injection valve. On vehicles with direct injection systems a distinction is made between the low-pressure area – from the filler neck up to the injection pump – and the high-pressure area which is located between the injection pump and the injector. In addition, the temperature requirements significantly differ between applications close to the fuel tank and those close to the engine.
Polymer components coming into contact with fuel have to meet the following general demands:
• Temperature resistance from -40 to + 200 °C (in the engine bay)
• Long life fatigue strength at high pressures and vibrations
• Extreme application-specific pressure loads
• Excellent mechanical properties such as compression set, tensile strength and ultimate elongation
• Media resistance and low permeation in contact with fuels such as
- Diesel fuel EN 590
- Biodiesel RME, SME
- Gasoline EN228
- Gasoline with ethanol and methanol admixtures
Parker Prädifa supplies customer-specific components and assemblies made of FKM, FVMQ, HNBR, FFKM, PTFE and PEEK for all applications in the fuel system. Special materials with higher electrical conductivity to avoid static charging are available as well.
Engine power / torque can only be put on the road via the wheels due to the interaction of these components. The transmission’s job is to adapt the engine’s torque as demanded by the driving condition according to the gear selected by the driver.
Depressing the clutch pedal (disengagement) releases the connection between the engine and the manual transmission allowing gears to be changed because the gears in the transmission are now freely movable. After engaging the desired gear the clutch pedal is released again (engagement). Spring elements reduce the vibrations that occur while engaging and disengaging the clutch.
The transmission contains a large number of precision shafts and gear wheels. Transmission oil reduces the friction between the gear wheels. This means that the housing must be sealed accordingly. Parker Prädifa has developed materials for use at the various sealing points.
For dynamic sealing points, they include A9164-75 (AEM), E3676-70 (EPDM), E9135-80 (EPDM), N9178-70 (HNBR) and N9192-75 (HNBR). As new pump generations operate with increasingly low pressures resulting in higher wear and higher friction the development of these materials was focused on optimization. This is also achieved, for example, by special designs of the sealing lips verified by FEA calculations.
Materials for dynamic sealing points in transmissions:
• Material Data Sheet E3676-70 (EPDM)
• Material Data Sheet E9135-80 (EPDM)
• Material Data Sheet N9178-70 (HNBR)
• Material Data Sheet N9192-75 (HNBR)
Hybrid electric drive systems basically combine two propulsion concepts: a conventional internal combustion (IC) engine and an electric motor. There are various concepts which are classified according to their system structure (series, parallel and power-split hybrids) and proportion of electric power output (micro hybrid, mild hybrid, full hybrid and range extender). Whereas the batteries of “classic” hybrid drive systems are charged by the IC engine while the vehicle is in motion the increasingly popular plug-in hybrids additionally offer the opportunity to charge the batteries by plugging them directly into a power outlet, which makes it possible to further reduce the fuel consumption of the IC engine.
Besides its main advantage of enabling locally emission-free driving without consuming fossil fuels, the electric motor of a hybrid electric vehicle (HEV) offers benefits when starting from rest or accelerating. In addition, the IC engine of an HEV can operate in a more favorable efficiency range more frequently and for longer periods of time which in turn has a positive effect on fuel consumption and emissions.
The IC engine is typically shut off during downhill driving, braking or coasting.
From a certain speed onward and on longer distances, the hybrid system switches to IC engine mode. The IC engine is able to use excess energy generated during braking for instance (so-called recuperation energy) to produce electricity for the electric traction motor.
As mentioned above, batteries of plug-in hybrid models can also be charged directly from a power outlet.
Both versions produce excess heat due to the necessity of transforming the different voltages between the battery and electric system and the electric motor. Therefore, the electronic components must be cooled. Specifically for water/glycol cooling systems, Parker Prädifa has developed the EPDM material E0529-60 which can economically be produced as larger moldings as well. For versions with thermal oil, the water resistant N8903 (HNBR) compound is available.
Materials for cooling systems in hybrid electric drive systems:
• Material Data Sheet E0529-60 (EPDM)
Unlike hybrid electric vehicles, fully electric vehicles are propelled exclusively by one or several electric motors. The required energy is supplied by batteries charged either by plugging them into charging stations or household sockets. Propelled by electricity as well are fuel cell vehicles that produce the electricity required by the traction motor(s) from the energy carriers hydrogen or methanol directly on board. Which technology will ultimately come out on top in electric mobility is not clear at the moment.
Current electric vehicles are typically equipped with a central electric motor. Its efficiency is clearly higher than that of classic IC engines. Due to diverse advantages such as enhanced efficiency, vehicle stability and active safety, the automotive industry is currently working on the development of so-called wheel hub motors for use in future electric production vehicles as well. As the name suggests, in this case, a traction motor is installed directly in each wheel.
In both cases, the battery supplies the electric motor with power.
Today’s battery electric vehicles almost exclusively use lithium-ion batteries in the cells of which substances such as solvents, conductive salts and additives in various combinations store the electricity. In this aggressive environment, seals also have to be resistant against highly toxic hydrofluoric acid.
For these applications, Parker has developed special EPDM materials such as E3750. For rubber or plastic composite parts, the E9195 compound is particularly well suited.
Materials for batteries in electric vehicles:
• Material Data Sheet E3750 (EPDM)
The growing pressure to reduce exhaust emissions, above all the greenhouse gas CO2 and nitrogen oxides that are harmful to human health, poses great challenges to the automotive industry. In the context of lowering harmful nitrogen oxides particularly in the emissions of diesel engines SCR (selective catalytic reduction) technology plays an important role.
In the SCR process, an aqueous urea solution (AdBlue® or AUS 32, Arla 32 and in North America referred to as Diesel Exhaust Fluid) is injected into the exhaust system where it is converted into ammonia by means of hydrolysis occurring in the system. The ammonia that is subsequently directed into the catalytic converter reacts there with the nitrogen oxides to produce harmless water and nitrogen.
Generally, the selection of elastomer materials for seals, besides the physical and thermal loads, primarily depends on the medium against which sealing is required. Its reaction with the sealing material must be minimized. A wrong selection of the seal’s material can clearly reduce the seal’s performance or even destroy the seal, for instance due to swelling, shrinking, brittleness, loss or increase of hardness.
The utilization of AdBlue® and the ammonia resulting from the SCR process has confronted the material developers in the elastomer industry with new challenges due to ammonia’s particular aggressiveness against sealing compounds.
Parker Prädifa has developed special EPDM and HNBR compounds for these applications which, in addition to the necessary cold flexibility down to -40 °C, exhibit low swelling tendency in contact with AdBlue® fluid. In addition, both material groups are superbly suited for connecting with the basic steel, stainless steel and plastics element. For diesel passenger cars, EPDM seals are typically used whereas HNBR seals have come out on top in the truck segment.
EPDM materials for SCR applications:
• Material Data Sheet E9180
• Material Data Sheet E8556
HNBR materials for SCR applications:
• Material Data Sheet N9182
• Material Data Sheet N8895
The use of common rail injection systems, aka accumulator injection systems, has become standard practice in diesel technology today. Due to the required enhancement of energy efficiency, there is a trend toward increasingly high injection pressures. Accordingly, sealing elements and sealing systems for pumps and injectors have to ensure operating pressures of up to 2,800 bar. In addition to media compatibility and pressure resistance, sealing elements of injectors particularly have to exhibit high temperature resistance due to their proximity to the combustion chamber.
Parker Prädifa has been supplying sealing elements and systems to nearly all manufacturers of common rail systems for many years. This includes the entire range of high-pressure seals for pumps and injectors. For injector seals exposed to very high temperatures, special PTFE materials have been developed which meet the diverse material specifications of the various manufacturers especially in terms of tensile strength. Thanks to proprietary elastomer compounds and specialized experience in O-ring technology, Parker Prädifa offers appropriate solutions for all relevant areas to be sealed.
For instance, Parker Prädifa’s universally usable material nobrox®, due to its excellent properties and minimal water absorption, has proven itself as an ideal material for back-up rings for injectors and can thus replace the previously used standard material polyamide (PA).
For pumps, reliable fluorosilicone sealing materials in combination with back-up elements made of specially filled PEEK materials are available. In these systems, the back-up element due to its extreme mechanical resistance prevents damage to the fluorosilicone seal resulting from gap extrusion at very high pressures.
FKM material for diesel injection valves:
• Material Data Sheet V3736
• Material Data Sheet V8558 (HiFluor® for high temperatures)
Fluorosilicone sealing systems (in combination with back-up elements):
• Material Data Sheet L0806