Lighter Powertrain Systems Help Increase Fuel Efficiency
Auto powertrain systems provide an opportunity to reduce vehicle weights and increase fuel efficiency, while reducing the total cost of the system at the same time.
Replacing metal components with lighter plastics offers a positive change in how powertrain systems are designed and produced. This is possible in part due to the properties offered by the DuPont™ Zytel® PLUS nylon family of products. Zytel® PLUS products are remarkably durable in high-heat, harsh-chemical environments found in underhood applications that used to be exclusively made with metals.
Supplying the Raw Materials For Innovation
Using only metal materials for production of powertrain system components isn’t a long-term answer for sustainable mobility. Metals are limited by their mass, manufacturing processes, and physical properties that add weight and limit design flexibility.
In addition to reduced vehicle weight, performance polymers offer more design and tooling flexibility for powertrain systems, compared to metals, also providing an extended tool life and reduced total system costs. For example, a typical injection-molded polymer part will have a tool life of over one million units, while die-cast aluminum and magnesium parts typically have a much shorter tool life of about 70,000 to 100,000 units.
Making a Lasting Difference
In addition, the properties of polymers can help users with integration of multiple parts and functionality for lighter, simpler, more cost-effective powertrain systems. The opportunity for improved fuel efficiency is clear - reducing an automobile’s weight by a mere 50 kg (110 lbs) reduces up to 5 g of carbon dioxide per kilometer and increases fuel economy by up to 2%.
Making Parts and Processes Better
As automakers build smaller engines, power-boost technologies, like turbocharging, are being used to deliver the performance needed to satisfy the demands of car-buying consumers. Turbocharging systems introduce higher temperatures and pressures, as well as more exhaust gas recirculation (EGR), resulting in exposure to a more aggressive mix of chemicals.
DuPont offers several materials for turbochargers and emissions systems that can withstand these new conditions: in addition to typical Zytel® products, DuPont™ Zytel® PLUS nylon and DuPont™ Zytel® HTN92 Series PPA resins offer high performance for these demanding applications. These resins are based on our SHIELD technology, and offer a leap in thermal oxidation resistance, which can support long-term heat aging performance.
A Portfolio of Products that Outperform
The Zytel® PLUS portfolio includes a range of grades that outperform traditional nylons for both heat and chemical resistance. For powertrain systems, these properties can support the opportunity to double the lifetime of certain engine components, relative to standard, heat-stabilized nylon. This creates an opportunity to replace metal components in applications that plastic materials could not handle before.
More Choices and More Ways to Use Them
Working together with OEMs and all tiers of the supply chain, our material science and application development resources help evaluate designs, operating conditions and manufacturing processes to help car manufacturers specify the right grade of Zytel® PLUS, or one of our other materials. DuPont works with these powertrain systems engineers, designers and manufacturers to help predict expected part performance over the life of the vehicle. From regional development centers in Asia, Europe and the Americas, we can model, analyze and help optimize component design and performance. DuPont works in collaboration with OEMs and suppliers, from concept to commercial launch and production.
Example 1: Managing Hot Gases
To meet higher temperature requirements, high EGR (exhaust-gas recirculation) rates, and modular design approaches, turbocharger air duct systems are moving away from heavier and costly aluminum, stainless and galvanized steel.
Today’s solution is high-temperature semi-aromatic polyimides (PPAs) such as DuPont™ Zytel®HTN high-performance polyamide resins. These high-performance plastics support advanced design and integration in air duct systems. Integration of parts can eliminate the need for clamps, brackets and silicone boots, making assembly easier and more efficient.
For example, the DuPont Global Blow Molding Technical Center in Geneva produces 3-D suction blow molded and co-extruded pipes that can combine a turbocharger charge-air cooler with the engine’s air intake manifold. And “Hot-side” air ducts are under development, using our high-temperature nylon HSLX resin, which has temperature resistance up to 210°C.
Example 2: Reducing Friction
Improving powertrain efficiency by reducing friction and wear can help reduce fuel consumption and durability. By defining a set of critical material properties that impact wear at high temperatures, DuPont scientists have been able to demonstrate improvements in wear in the range of 60-70% with materials like Vespel® SCP resins, when compared with current materials.
For example, a plate on a disc system with a lubricant in between the rotating surfaces is commonly found in driveline applications, such as thrust washers and seal rings. By carefully optimizing material selection and design guidelines, while considering the thermal needs of the system, we have been able to demonstrate 45 to 55% reduction in measured friction — a significant gain for several rotating driveline components.
Automakers have seen improved performance in EGR valves after evaluating Vespel® SCP materials in emission valve applications exposed to high levels of soot and coke particles. These particles contribute to both wear problems and actuation speed problems, primarily due to the change in friction properties over time.