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Mo-free 1.6-GPa bolt was developed for a Variable Compression Turbo (VC-Turbo) engine, which is environment friendly and improves fuel efficiency and output. Mo contributes to the improvement of delayed fracture resistance; therefore, the main objective is to achieve both high strength and delayed fracture resistance. Therefore, Si is added to the developed steel to achieve high strength and delayed fracture resistance. The delayed fracture tests were performed employing the Hc/He method. Hc is the limit of the diffusible hydrogen content without causing a delayed fracture under tightening, and He is the diffusible hydrogen content entering under a hydrogen-charging condition equivalent to the actual environment. The delayed fracture resistance is compared between the developed steel and the SCM440 utilized for 1.2-GPa class bolt as a representative of the current high-strength bolts.

To improve the fuel economy, we developed a turbo-charged spark ignition engine combined with a low pressure loop EGR system. A negative pressure control valve has been applied to achieve high EGR ratio in wide engine operation condition. In this paper, a new developed model-based control system for low pressure loop EGR with a negative pressure control valve will be described.

A gasoline particulate filter (GPF) is installed in a passenger vehicle for new exhaust regulation. However, ash in gasoline engine oil has a risk of clogging as well as performance decrease in the GPF. Therefore, new gasoline engine oil whose ash contents decrease to 0.8 mass% was developed in order to avoid the GPF clogging. In addition to this, our developed oil improves fuel efficiency (+0.2% from our SN 0W-16 fuel eco type oil) as well as anti-wear performance for gasoline engine, which resulted in meeting API SP/ILSAC GF-6 0W-16 official certification.

Knock in gasoline engines at higher loads is a significant constraint on torque and efficiency. The anti-knock property of a fuel is closely related to its research octane number (RON). Ethanol has superior RON compared to gasoline and thus has been commonly used to blend with gasoline in commercial gasolines. However, as the RON of a fuel is constant, it has not been used as needed in a vehicle. To wisely use the RON, an On-Board Separation (OBS) unit that separates commercial gasoline with ethanol content into high-octane fuel with high ethanol fraction and a lower octane remainder has been developed. Then an onboard Octane-on-demand (OOD) concept uses both fuels in varying proportion to provide to the engine a fuel blend with just enough RON to meet the ever changing octane requirement that depends on driving pattern.

Three-piece oil control rings (TPOCR) are widely used in the majority of modern gasoline engines and they are critical for lubricant regulation and friction reduction. Despite their omnipresence, the TPOCRs’ motion and sealing mechanisms are not well studied. With stricter emission standards, gasoline engines are required to maintain lower oil consumption limits, since particulate emissions are strongly correlated with lubricant oil emissions. This piqued our interest in building a numerical model coupling TPOCR dynamics and oil transport to explain the physical mechanisms. In this work, a 2D dynamics model of all three pieces of the ring is built as the main frame. Oil transport in different zones are coupled into the dynamics model. Specifically, two mass-conserved fluid sub-models predict the oil movement between rail liner interface and rail groove clearance to capture the potential oil leakage through TPOCR. The model is applied on a 2D laser induced fluorescence (2D-LIF) engine.

Nissan’s variable compression turbo (VC-Turbo) engine has a multilink mechanism that continuously adjusts the top and bottom dead centers of the piston to change the compression ratio and achieve both fuel economy and high power performance. Increasing the exhaust gas recirculation (EGR) rate is an effective way to further reduce the fuel consumption, although this increases the exhaust gas condensation in the cylinder bores, causing a more corrosive environment. When the EGR rate is increased in a VC-Turbo engine, the combined effect of piston sliding and exhaust gas condensation at the top dead center accelerates the corrosive wear of the thermal spray coating. Stainless steel coating is used to improve the corrosion resistance, but the adhesion strength between the coating and the cylinder bores is reduced.

Engine oil with viscosity lower than 0W-16 has been needed for improving fuel efficiency in the Japanese market. However, lower viscosity oil generally has negative aspects with regard to oil consumption and anti-wear performance. The technical challenges are to reduce viscosity while keeping anti-wear performance and volatility level the same as 0W-20 oil. They have been solved in developing a new engine oil by focusing on the molybdenum dithiocarbamate friction modifier and base oil properties. This paper describes the new oil that supports good fuel efficiency while reliably maintaining other necessary performance attributes.

It is well understood that using lower viscosity engine oils can greatly improve fuel economy [1, 2, 3, 4]. However, it has been impossible to evaluate ultra-low viscosity engine oils (SAE 0W-12 and below) utilizing existing fuel economy test methods. As such, there is no specification for ultra-low viscosity gasoline engine oils [5]. We therefore developed firing and motored fuel economy test methods for ultra-low viscosity oils using engines from Japanese automakers [6, 7, 8]. This was done under the auspices of the JASO Next Generation Engine Oil Task Force (“TF” below), which consists mainly of Japanese automakers and entities working in the petroleum industry. Moreover, the TF used these test methods to develop the JASO GLV-1 specification for next-generation ultra-low viscosity automotive gasoline engine oils such as SAE 0W-8 and 0W-12. In developing the JASO GLV-1 specification, Japanese fuel economy tests and the ILSAC engine tests for evaluating engine reliability were used.

During this decade, the constant increase and globalization of passenger car sales has led countries to adopt a common language for the treatment of CO2 and other pollutant emissions. In this regard, the WLTC - World-wide harmonized Light duty Test Cycle - stands as the new global reference cycle for fuel consumption, CO2 and pollutant emissions across the globe. Regulations keep a constant pressure on CO2 emission reduction leading vehicle manufacturers and component suppliers to modify hardware to ensure compliance. Within this balance, lubricants remain worthwhile contributors to lowering CO2 emission and fuel consumption. Yet with WTLC, new additional lubricant designs are likely to be required to ensure optimized friction due to its new cycle operating conditions, associated powertrain hardware and worldwide product use.

The mechanism causing in-cylinder injector tip soot formation, which is the main source of particle number (PN) emissions under operating conditions after engine warm-up, was analyzed in this study. The results made clear a key parameter for reducing injector tip soot PN emissions. An evaluation of PN emissions for different amounts of injector tip wetting revealed that an injector with larger tip wetting forms higher PN emissions. The results also clarified that the amount of deposits does not have much impact on PN emissions. The key parameter for reducing injector tip soot is injector tip wetting that has a linear relationship with injector tip soot PN emissions.

A new variable compression turbo (VC-Turbo) engine, which has a multi-link system for controlling the compression ratio from 8:1 to 14:1, requires high axial force for fastening the multi-links because of high input loads and the downsizing requirement. Therefore, it was necessary to develop a 1.6-GPa tensile strength bolt with plastic region tightening. One of the biggest technical concerns is delayed fracture. In this study, quenched and tempered alloy steels were chosen for the 1.6-GPa tensile strength bolt.

Accumulation of lubricant and fuel derived ash in the diesel particulate filter (DPF) during vehicle operation results in a significant increase of pressure drop across the after-treatment system leading to loss of fuel economy and reduced soot storage capacity over time. Under certain operating conditions, the accumulated ash and/or soot cake layer can collapse resulting in ash deposits upstream from the typical ash plug section, henceforth termed mid-channel ash deposits. In addition, ash particles can bond (either physically or chemically) with neighboring particles resulting in formation of bridges across the channels that effectively block access to the remainder of the channel for the incoming exhaust gas stream. This phenomenon creates serious long-term durability issues for the DPF, which often must be replaced. Mid-channel deposits and ash bridges are extremely difficult to remove from the channels as they often sinter to the substrate.

Internal combustion engines for plug-in hybrid heavy duty trucks, especially long haul trucks, could play an important role in facilitating use of battery power. Power from a low carbon electricity source could thereby be employed without an unattractive vehicle cost increase or range limitation. The ideal engine should be powered by a widely available affordable liquid fuel, should minimize air pollutant emissions, and should provide lower greenhouse gas emissions. Diesel engines could fall short in meeting these objectives, especially because of high emissions. In this paper we analyze the potential for a flex fuel gasoline-alcohol engine approach for a series hybrid powertrain. In this approach the engine would provide comparable (or possibly greater) efficiency than a diesel engine while also providing 90 around lower NOx emissions than present cleanest diesel engine vehicles. Ethanol or methanol would be employed to increase knock resistance.

In recent years, boosted and downsized engines have gained much attention as a promising technology to improve fuel economy; however, knocking is a common issue of such engines that requires attention. To understand the knocking phenomenon under downsized and boosted engine conditions deeply, fuels with different Research Octane Number (RON) and Motor Octane Number (MON) were prepared, and the knocking performances of these fuels were evaluated using a single cylinder engine, operated under a variety of conditions. Experimental results showed that the knocking performance at boosted conditions depend on both RON and MON. While higher RON showed better anti-knocking performance, lower MON showed better anti-knocking performance. Furthermore, the tendency for a reduced MON to be beneficial became stronger at lower engine speeds and higher boost pressures, in agreement with previously published modelling work.

This article reports on the potential of negative valve overlap (NVO) for improving the net indicated thermal efficiency (η NIMEP) of gasoline engines during part load. Three fixed fuel flow rates, resulting in indicated mean effective pressures of up to 6 bar, were investigated. At low load, NVO significantly reduces the pumping loses during the gas exchange loop, achieving up to 7% improvement in indicated efficiency compared to the baseline. Similar efficiency improvements are achieved by positive valve overlap (PVO), with the disadvantage of worse combustion stability from a higher residual gas fraction (xr). As the load increases, achieving the wide-open throttle limit, the benefits of NVO for reducing the pumping losses diminish, while the blowdown losses from early exhaust valve opening (EVO) increase.

Higher compression ratio and turbocharging, with engine downsizing can enable significant gains in fuel economy but require engine operating conditions that cause engine knock under high load. Engine knock can be avoided by supplying higher-octane fuel under such high load conditions. This study builds on previous MIT papers investigating Octane-On-Demand (OOD) to enable a higher efficiency, higher-boost higher compression-ratio engine. The high-octane fuel for OOD can be obtained through On-Board-Separation (OBS) of alcohol blended gasoline. Fuel from the primary fuel tank filled with commercially available gasoline that contains 10% by volume ethanol (E10) is separated by an organic membrane pervaporation process that produces a 30 to 90% ethanol fuel blend for use when high octane is needed. In addition to previous work, this paper combines modeling of the OBS system with passenger car and medium-duty truck fuel consumption and octane requirements for various driving cycles.

The performance of an extended stroke spark ignition engine has been assessed by cycle simulation. The base engine is a modern turbo-charged 4-stroke passenger car spark-ignition engine with 10:1 compression ratio. A complex crank mechanism is used so that the intake stroke remains the same while the expansion-to-intake stroke ratio (SR) is varied by changing the crank geometry. The study is limited to the thermodynamic aspect of the extended stroke; the changes in friction, combustion characteristic, and other factors are not included. When the combustion is not knock limited, an efficiency gain of more than 10 percent is obtained for SR = 1.5. At low load, however, there is an efficiency lost due to over-expansion. At the same NIMEP, the extended stroke renders the engine more resistant to knock. At SR of 1.8, the engine is free from knock up to 14 bar NIMEP at 2000 rpm. Under knocking condition, the required spark retard to prevent knocking is less with the extended stroke.

Long-haul and other heavy-duty trucks, presently almost entirely powered by diesel fuel, face challenges meeting worldwide needs for greatly reducing nitrogen oxide (NOx) emissions. Dual-fuel gasoline-alcohol engines could potentially provide a means to cost-effectively meet this need at large scale in the relatively near term. They could also provide reductions in greenhouse gas emissions. These spark ignition (SI) flexible fuel engines can provide operation over a wide fuel range from mainly gasoline use to 100% alcohol use. The alcohol can be ethanol or methanol. Use of stoichiometric operation and a three-way catalytic converter can reduce NOx by around 90% relative to emissions from diesel engines with state of the art exhaust treatment.

During the last decade, fuel economy mandates (CAFE regulations) have driven engine downsizing and down-speeding trends. More recently, downsized turbos are percolating down to heavier SUVs and trucks. Larger/heavier vehicles require high torque engines to provide attractive dynamic performance. While higher torque requirements can be satisfied with new innovations like the variable compression engine, larger and more upscale vehicles also need to deliver higher quietness requirements. For this, the vibration control system for combustion induced forces with high torque engines become very important. To address both dynamic performance and quietness requirements, active engine mounts have been previously adopted, however challenges for light-weighting, downsizing, and costs have still persisted.

In internal combustion engines, a portion of liquid fuel spray may directly land on the liner and mix with oil (lubricant), forming a fuel-oil film (~10μm) that is much thicker than the original oil film (~0.1μm). When the piston retracts in the compression stroke, the fuel-oil mixture may have not been fully vaporized and can be scraped by the top ring into the 1st land crevice and eventually enter the combustion chamber in the format of droplets. Studies have shown that this mechanism is possibly a leading cause for low-speed pre-ignition (LSPI) as the droplets contain oil that has a much lower self-ignition temperature than pure fuel. In this interest, this work aims to study the oil-fuel interactions on the liner during an engine cycle, addressing molecular diffusion (in the liquid film) and vaporization (at the liquid-gas interface) to quantify the amount of fuel and oil that are subject to scraping by the top ring, thereby exploring their implications on LSPI and friction.