Customer demand and government regulations continue to push the automotive industry to improve efficiency, and many of these improvements affect seal materials and seal material selection. But how and why would this impact the seals in a vehicle? It may surprise you how far reaching many of these changes extend.
In general, efficiency improvements can be lumped into one of several categories: engine improvements, transmission advances, electrification / hybridization, aerodynamics, weight reduction, and accessories. I’ll focus primarily on advances in engine technology that are causing the industry to reassess seal material selection, in some cases dramatically.
Engine modifications can be boiled down to a single phrase: “Do more with less". Go further on a gallon of fuel. Or to put it another way, create the same amount of usable horsepower and torque with a smaller engine that burns less fuel. They’re two sides of the same coin. There are many ways to squeeze out efficiency, and most of them place increasing demands on elastomer seals.
One “trick” auto manufacturers have been using for several years is to use lower viscosity engine oil. This reduces the amount of power needed to pump oil throughout the engine, which means less of the engine’s power gets used up running itself. Synthetic 0W16 oils are now entering the market, with further reductions on the horizon. These ultra low viscosity oils are increasingly aggressive to the polyacrylate (ACM), ethylene acrylic (AEM), hydrogenated nitrile (HNBR), and Type 1 (“standard”) fluorocarbon (FKM) elastomers that have traditionally been used in engine oil applications. They have minimal impact on Type 3 (low temperature) FKM materials such as Parker’s VG292-75 and V1289-75 compounds, but these materials are more expensive than the incumbent materials. Will lower viscosity oils push car manufacturers to upgrade the seals used in engine oil applications?
Another engine improvement is the increasingly widespread use of Gasoline Direct Injection (GDI) and Turbodiesel Direct Injection (TDI). In these engine designs, fuel is precisely measured and injected directly into the combustion chamber rather than into the intake air. Pressures in the injection system must be higher than the pressure inside the combustion chamber, which currently means fuel system pressures up to 50 MPa (7,000 psi). The GLT and GFLT-type fluorocarbon compounds that have been used for the last several decades are simply not capable of meeting the high pressure and low temperature demands coupled with the need for improved resistance to methanol and biodiesel. Enter Parker compounds VG286-80 and VG109-90. Both materials offer improved low temperature performance over GLT-type FKMs and resistance to methanol and biodiesel that’s almost as good as the GFLT-type materials, plus pressure resistance that reaches to 70 MPa (10,000 psi) or higher.
A third engine improvement is the expansion of turbocharging. Popular among high performance sports cars and race cars, turbocharging offers the higher horsepower and torque of a larger engine in a smaller, lighter, more efficient engine block. Power is available when needed, but not wasted during light duty cruising.
However, turbochargers get hot. Hotter than elastomers can typically withstand for any length of time. So, standard designs run engine coolant to the turbocharger, but that presents another challenge: the elastomers that work best in high temperature applications aren’t very resistant to hot water and glycol coolants. There are, however, notable exceptions. Parker’s VG292-75 and VG310-75 fluorocarbon compounds offer outstanding coolant resistance and thermal stability up to 200 °C. For even more aggressive applications, Parker’s FF400-80 perfluoroelastomer can cover the range of -40 to +250 °C with good coolant resistance, but that level of high performance comes with a high performance price tag, as well.
Vehicle designs are pushing the limits on fuel economy, and these advances are placing increasing demands on rubber seals. Fortunately, Parker already has solutions for many of these challenging applications available and in production today. For additional information on the best material to solve your sealing challenges, please contact our engineers via online chat at Parker O-Ring & Engineered Seals Division.
This article contributed by Dan Ewing, senior chemical engineer, Parker Hannifin O-Ring & Engineered Seals Division.