Towards Improving Fuel Economy through Tribology Testing
Dr Richard Baker (PCS Instruments)
London, United Kingdom email@example.com
Dr Clive Hamer (PCS Instruments), London, United Kingdom
Global passenger car sales rose by 7.2% to 66.6 million vehicles in 2012, exceeding the previous record achieved in 2011. All regions contributed to this success, with the exception of Western Europe. In particular, double-digit growth rates in the markets of North America and in the Asia-Pacific region bolstered this development. Demand in South America reached an all-time high. Global passenger car production rose by 6.0% to 70.5 million units in the reporting period.
Only about 14%–26% of the energy from the fuel you put in your tank gets used to move your car down the road, depending on the drive cycle. The rest of the energy is lost to engine and driveline inefficiencies or used to power accessories. Therefore, the potential to improve fuel efficiency with advanced technologies is enormous.
The energy losses can be separated into Engine Losses (65-75%), Parasitic Loses (3-7%) and Drivetrain Losses (4-7%).
This presentation will look at the history of fuel economy progression and review each of these energy losses in more detail. It will explain how lubricant manufacturers, through testing with now standard tribology test equipment, are looking to improve each of these areas and highlight the progress that has been made over the past 50 years.
History of Fuel Economy
In the United States, in response to the oil price shocks of the early 1970s (due to the Arab oil embargo), the US Congress passed the nation’s first Corporate Average Fuel Economy (CAFE) standards in 1975, designed to improve the average fuel economy of cars and light trucks (trucks, vans and SUV’s) sold in the US. The law called for a doubling of passenger-vehicle efficiency—to 27.5 miles per gallon (mpg)—within 10 years. Previous to 1975, there was no regulation for a fuel economy target.
From 1975 to 1985, vehicle fuel economy doubled from about 13.5 mpg to 27.5, while fuel economy for light trucks increased from 11.6 mpg to 19.5. In the mid 1980’s, however, Ford and General Motors successfully lobbied the US government to lower the passenger car standard to 26 mpg, where it stayed until 1989.
In 1990, 2 senators Richard Bryan and Slade Gorton sponsored legislation that would raise fuel-economy standards for cars and light trucks by 40 percent over a decade. It was passed by the commerce committee but lost out in the Senate. Had it passed, the United States would now be saving more than a million barrels of oil per day.
2000 – Present and Future
In December 2007, Congress passed the first changes to U.S. fuel-economy standards in nearly 20 years. In April 2009, President Obama accelerated the increase in the previous administration’s CAFE standards. The joint Environmental protection Agency/NHTSA rule applies to model years 2012 to 2016, requiring a fleet-wide average of 35.5 mpg by 2016. Increasing at an average of 5 percent annually, most passenger cars must achieve 39 mpg, and light trucks 30 mpg, by 2016.
In October 2010, the administration proposed a CAFE standard for medium and heavy-duty trucks. The program is projected to save 500 million barrels of oil and 250 million metric tons of carbon dioxide emissions in the first five years. Covered vehicles would be separated by type and fuel, with fuel-economy improvements of 20 percent for combination tractors, 10 percent for gasoline trucks and vans, and 10 percent for diesel trucks and vans and all vocational vehicles (such as dump trucks and cement mixers) by model year 2018.
Future Fuel economy
Current European original equipment manufacturers (OEM’s) in the automotive industry requirements for today’s passenger car motor oils are 20,000 to 30,000 kilometer (approximately 12,500 to 18,750 miles) drain intervals, excellent wear protection, engine cleanliness, compatibility with exhaust aftertreatment devices and fuel economy. While these needs are being met by SAE 5W-30 viscosity grades, in the future OEMs will place far more severe constraints on passenger car engine oils.
Future engine oils will have to deliver a better fuel economy, while still maintaining the long drain intervals and compatibility with exhaust aftertreatment devices. For this reason, the future requirements will be towards SAE 5W-20 or SAE 0W-20 viscosity grade oils, formulated with additives that have minimal amounts of sulphated ash, phosphorous and sulphur (SAPS).
Lubrizol have recently presented work to show how a typical ACEA C3 5W-30 oil will on average improve fuel economy by 2 percent compared to a conventional oil, while a typical ACEA C2 5W-30 yields a 2.7 percent improvement. Based on current work that Lubrizol has performed with 0W-20 oils, there is potential to improve the average fuel economy rating of around 4 percent.
The best passenger car engine lubricants are currently about 4-5% more efficient than their early 1990s counterparts as a result of lubricant development. This increase in efficiency corresponds to an annual reduction of nearly 4´10 kg (about 0.1%) of global man-made CO emissions. A large proportion of this research work has been performed using commercially available desktop tribology equipment produced by PCS Instruments. In the period 2008-2012, PCS Instruments Mini-Traction machine (MTM) and the PCS Instruments High Frequency Reciprocating Rig (HFRR) were cited in 380 US patent applications and in 113 granted US patents. PCS test rigs have also been sold to over 40 University research groups world-wide, making them one of the most widely-used categories of equipment in tribology research laboratories.
Results will be presented to show the effectiveness of engine oil formulations in decreasing friction, and hence improving the fuel economy on passenger cars on the PCS MTM instrument.
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7 Beercheck, R More Challenges Loom for Engine Oils, Lubes’N’Greases, June 2013