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Technical Paper

The Effect of Friction Modifiers and DI Package on Friction Reduction Potential of Next Generation Engine Oils: Part II Aged Oils

Engine oil plays an important role in improving fuel economy of vehicles by reducing frictional losses in an engine. Our previous investigation explored the friction reduction potential of next generation engine oils by looking into the effects of friction modifiers and dispersant Inhibitor packages when engine oil was fresh. However, engine oil starts aging the moment engine start firing because of high temperature and interactions with combustion gases. Therefore, it is more relevant to investigate friction characteristics of aged oils. In this investigation, oils were aged for 5000 miles in taxi cab application.
Technical Paper

Effect of Ash on Gasoline Particulate Filter Using an Accelerated Ash Loading Method

Gasoline particulate filter (GPF) is considered a suitable solution to meet the increasingly stringent particle number (PN) regulations for both gasoline direct injection (GDI) and multi-port fuel injection (MPI) engines. Generally, GDI engines emit more particulate matter (PM) and PN. In recent years, GDI engines have gained significant market penetration in the automobile industry owing to better fuel economy and drivability. In this study, an accelerated ash loading method was tested by doping lubricating oil into the fuel for a GDI engine. Emission tests were performed at different ash loads with different driving cycles and GPF combinations. The results showed that the GPF could significantly reduce particle emissions to meet the China 6 regulation. With further ash loading, the filtration efficiency increased above 99% and the effects on fuel consumption and backpressure were found to be limited, even with an ash loading of up to 50 g/l.
Journal Article

Impact of Particle Characteristics and Engine Conditions on Deposit-Induced Pre-Ignition and Superknock in Turbocharged Gasoline Engines

Low Speed Pre-Ignition (LSPI), also referred to as superknock or mega-knock is an undesirable turbocharged engine combustion phenomenon limiting fuel economy, drivability, emissions and durability performance. Numerous researchers have previously reported that the frequency of Superknock is sensitive to engine oil and fuel composition as well as engine conditions in controlled laboratory and engine-based studies. Recent studies by Toyota and Tsinghua University have demonstrated that controlled induction of particles into the combustion chamber can induce pre-ignition and superknock. Afton and Tsinghua recently developed a multi-physics approach which was able to realistically model all of the elementary processes known to be involved in deposit induced pre-ignition. The approach was able to successfully simulate deposit induced pre-ignition at conditions where the phenomenon has been experimentally observed.
Journal Article

A General Method for Fouling Injectors in Gasoline Direct Injection Vehicles and the Effects of Deposits on Vehicle Performance

The ubiquity of gasoline direct injection (GDI) vehicles has been rapidly increasing across the globe due to the increasing demand for fuel efficient vehicles. GDI technology offers many advantages over conventional port fuel injection (PFI) engines, such as improvements in fuel economy and higher engine power density; however, GDI technology presents unique challenges as well. GDI engines can be more susceptible to fuel injector deposits and have higher particulate emissions relative to PFI engines due to the placement of the injector inside the combustion chamber. Thus, the need for reliable test protocols to develop next generation additives to improve GDI vehicle performance is paramount. This work discloses a general test method for consistently fouling injectors in GDI vehicles and engines that can accommodate multiple vehicle/engine types, injector designs, and drive cycles, which allows for development of effective GDI fuel additives.
Technical Paper

Continuously Variable Transmission (CVT) Fuel Economy

Due to its simplicity and fuel economy benefit, continuously variable transmission (CVT) technology has gained a lot of attention in recent years. Market penetration of CVT technology is increasing rapidly compared to step-type automatic transmission technology. OEMs, Tier 1 suppliers, and lubricant suppliers are working to further improve the fuel economy benefit of CVTs. As a lubricant supplier, we want to understand the effects of fluid properties on CVT fuel economy (FE). We have formulated fluids that had KV100 ranges from 2-4 cSt to 7-9 cSt with various types and viscosities of base oils. Wide ranges of viscosity indexes, steel-on-steel friction, and other properties were tested. Full vehicle fuel economy tests were performed in a temperature controlled environment with a robotic driver. The test revealed that there was more than 3% overall FE variation compared to a reference fluid.
Technical Paper

Fluid Effects on Shifting Clutch Friction

Good shift quality in automatic transmissions is important for fuel efficiency, driver comfort, and performance. Maintaining this performance over the life of the vehicle is also important. Typically lubricant development focuses on reducing viscosity and friction in order to reduce parasitic losses. In an automatic transmission other factors are also important for good performance, primarily due to the shifting clutches and the torque converter clutch. A high level of friction is desirable for torque capacity and a steady decrease in friction as sliding speed (rpm) decreases is necessary for both good shift feel and good friction system durability over the lifetime of the vehicle. Changes in the friction system over time that result in a lowering of the friction level, particularly at higher sliding speeds, compromise the performance of both types of clutches.
Technical Paper

Effect of Oil and Gasoline Properties on Pre-Ignition and Super-Knock in a Thermal Research Engine (TRE) and an Optical Rapid Compression Machine (RCM)

High boost and direct injection are effective ways for energy saving in gasoline engines. However, the occurrence of super-knock at high load has become a main obstacle for further improving power density and fuel economy. It has been known that super-knock can be induced by pre-ignition, and oil droplet auto-ignition is found to be one of the possible mechanisms. In this study, experiments were conducted in a single-cylinder thermal research engine (TRE), in which different types of oil and surrogates were directly injected into the cylinder and then led to pre-ignition and super-knock. The effect of oil injection timing, oil injection quantity, different gasoline and different oil were tested. All the oil in this work could induce pre-ignition, even though their combustion phasing was much later than that in the case of n-hexadecane.
Technical Paper

Correlation of the Sequence VID Laboratory Fuel Economy Test to Real World Fuel Economy Improvements

When gasoline-fueled vehicles are operated in consumer service, the oil used to lubricate the engine plays a key role in engine cooling, reducing friction, maintaining efficient operation, and optimizing fuel economy. The effects of normal vehicle operation on oil deterioration have a direct impact on fuel consumption. The authors have observed substantial differences between the deterioration of engine oil and resulting fuel economy under real-world driving conditions, and the deterioration of oils and resulting fuel economy in the standard laboratory test used to assess fuel economy in North America, the Sequence VID engine test (ASTM D7589). By analyzing the data from vehicles and comparing these data to the Sequence VID the authors have proposed and evaluated several changes to the Sequence VID test that improve the correlation with real-world operation and improve test discrimination.
Journal Article

Development of a Novel Vehicle-Based Method to Assess the Impact of Lubricant Quality on Passenger Car Energy Efficiency

The traditional vehicle-based approach to measuring the effect of oil-related fuel economy has relied on separate oil-aging and measurement processes where oil-aging takes place using an established driving protocol like the EPA Approved Mileage Accumulation (AMA) Driving Schedule for vehicle aging, then at set mileage intervals fuel economy is assessed using procedures such as the EPA FTP75 and Highway Fuel Economy emission test protocols described in 40 CFR, Parts 86 and 600. These test methods are useful for producing discrete snapshots of fuel economy at set mileage intervals but are unable to provide continuous information about oil-related changes in fuel economy. During the tests, the vehicle's fuel economy is indirectly calculated using a carbon-balance method of the bagged sample of dilute tailpipe emissions that effectively integrates the fuel economy of the vehicle during the sample interval which varies between eight and fifteen minutes.
Journal Article

Fuel Economy Beyond ILSAC GF-5: Correlation of Modern Engine Oil Tests to Real World Performance

A host of bench and engine tests have historically been used by formulators to assess fuel economy when developing engine oils for gasoline-powered passenger cars and light trucks. Some of these methods assess basic lubricant physical properties such as hydrodynamic, boundary and thin-film friction, and are useful for quickly screening experimental components and formulations. Some methods assess rotational drag of a motored engine and offer insights into the friction of various engine parts. Still other methods directly measure the energy consumption in a test engine running in a research laboratory and thus come the closest to simulating a consumer-operated vehicle. Each test method has inherent limitations and is based on underlying assumptions, producing artifacts that must first be understood and then analyzed for relevance to either industry lubricant specifications or real world fuel economy performance.