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Described here is the tuning of the combustion systems of a precombustion chamber diesel engine for lower level of exhaust gas emission. The key points of the tuning are the decrease of the prechamber volume, the selection of the combustion chamber configuration, the injection nozzle characteristics and the optimum injection timing. It was made clear, in the results of investigation, that the degradation of lubricating oil and the cavitation pitting on the outer wall of cylinder liner were directly concerned with the combustion characteristics of low emission systems. And both problems have been solved. The result of combustion tuning of the engine shows less than 5 g/hp-h of NOx + HC with CARB 13 mode test cycle without deterioration of performance nor durability.

Described herein is the tuning of the combustion system of a direct injection type diesel engine to obtain low emission level and better fuel economy. Though the most important method of emission control for a direct injection system is considered to be timing retardation, it brings a higher level of smoke density and fuel consumption. In order to remove these faults, the authors developed a new combustion system based on a newly designed intake port which provides a favorable local mixing of fuel droplets and air in the combustion chamber for ignition by means of air turbulence. This new combustion system was analyzed with high speed photographs which were taken from the underside of the piston to enable observing the whole combustion chamber. Favorable characteristics of ignition and burning pattern of the new system were recognized by this analysis.

1 Many environmental problems, such as global warming, drain of fuel and so on, are apprehended in all over the world today, and down-sizing is one of the wise ways to deal with these problems. It is significant that a decrease of the engine power must not be produced by using a small displacement engine, so more efficient engine system should be designed to increase the torque with a little fuel. This study achieves an improvement of efficiency for mounting the super charging system on the small displacement engine. As a result, comparing a super charged engine and a naturally aspirated one to drive the same course and laps, fuel consumptions are 2547 [cc] and 3880 [cc], respectively, and an improvement of fuel consumption is 52%. Designing points to mount super charging system is introduced below. 1 It can be forecasted that intake air blow-by gas at the combustion chamber is increased in low engine speed because engine for motor cycle is used.

Fuel economy measurement test is one of important engine tests to establish fuel economy engine oil performance standard to support CO2 emission reduction efforts in the automotive industry. On the other hand, it is difficult to develop an engine test without appropriate engine hardware that is designed to utilize low viscosity engine oils. A new firing fuel economy test was developed based on 2ZR-FXE engine designed for hybrid powertrain. The new test procedure aimed to provide the tool to evaluate new low viscosity grades such as 0W-8 and 0W-12 that were adapted in SAE J300 in 2015.

A historical review of Japanese turbocharged diesel engines for heavy duty vehicles is described, and newly developed turbocharged diesel engines of HINO are introduced. The design features of these engines include new turbocharging technologies such as highly backward curved impeller for compressor blade, variable controlled inertia charging and waste gate. Laboratory and field test results demonstrated better fuel economy and improved low speed and transient torque characteristics than the predecessors. Several operational experiences, technical analysis and reliability problems are discussed.

We report in this paper our newly developed technology applied to ILSAC GF-5 0W-20 engine oil that offers great fuel economy improvement over GF-4 counterpart, which is a key performance requirement of modern engine oil to reduce CO2 emissions from a vehicle. Our development strategy of the oil consisted of two elements: (1) further friction reduction under mixed and hydrodynamic lubrication conditions considering use of roller rocker arm type valve train system and (2) lowering viscosity at low temperature conditions to improve fuel economy under cold cycles. Use of roller rocker arm type valve train system has been spreading, because of its advantage of reducing mechanical friction. Unlike engine with conventional direct-acting type valve train system, lubrication condition of engine with the roller rocker arm type valve train system has higher contribution of mixed or hydrodynamic lubrication conditions rather than boundary lubrication condition.

This paper presents technical solutions and a development process to accomplish not only superior fuel economy but also excellent driveability with a turbocharged diesel engine for heavy duty trucks. For better fuel economy, one of the basic considerations is how to decrease the friction losses of the engine itself while keeping the required horsepower and torque characteristics. A high boost turbocharged small engine offers this possibility, but it has serious disadvantages such as inferior low speed torque, poorer accelerating response, insufficient engine braking performance, and finally not always so good fuel consumption in the engine operating range away from the matching point between engine and turbocharger. These are not acceptable in complicated traffic conditions like those in Japan - a mixture of mountainous and hilly roads, city road with numerous traffic signals, and freeways.

Gasoline engine downsizing combined with a turbocharger is one of the more effective approaches to improve fuel efficiency without sacrificing power performance. The benefit comes from lower pumping loss, lower mechanical friction due to ‘downsizing’ of the engine displacement and ‘down-speeding’ of the engine by using higher transmission gear ratios which is allowed by the higher engine torque at lower engine speeds. However abnormal combustion referred to as Low-Speed Pre-ignition (LSPI) is known to be able to occur in low-speed and high-torque conditions. It is a potential restriction to maximize the engine performance and its benefit, therefore prevention of LSPI is strongly desired for long-term durability of engine performance. According to recent technical reports, auto-ignition of an engine oil droplet in a combustion chamber is believed to be one of major contributing factors of LSPI and its formulations have a significant effect on LSPI frequency.

Diesel engines need to optimize the fuel injection timing and quantity of each cycle in the transient operation to increase the thermal efficiency and reduce the exhaust gas emissions through the precise combustion control. The heat transfer from the working gas in the combustion chamber to the chamber wall is a crucial factor to predict the gas temperature in the combustion chamber to optimize the timing and quantity of fuel injection. Therefore, the authors developed both the heat loss and the polytropic index prediction models with the low calculation load and high accuracy. In addition, for the calculation of the heat loss and the polytropic index, the wall heat transfer model was also developed, which was derived from the continuity equation and the energy equation. The present study used a single cylinder diesel engine under the condition of engine speed of 1200 and 1500 rpm, and measured the local wall temperature and the local heat flux of the combustion chamber.

This investigation was concerned with the rate of heat transfer from the working gases to the combustion chamber walls of the internal combustion engines. The numerical formula for estimating the heat transfer to the combustion chamber wall was derived from the theoretical analysis and the experiment, which were used the constant volume combustion chamber and the actual gasoline engine. As a result, mean heat transfer in the internal combustion engine becomes possible to estimate with measuring the cylinder pressure. In addition, the derived numerical formula forms with quite simple variables. Therefore it is very useful for engine design.

The paper reviews the experimental development of fuel economy of engine powering the 2012 Formula SAE single seat race car of the University of Sophia. The balance of high power and low fuel consumption is biggest challenge of racing engine. It was found that improving the efficiency of engine by supercharging as a way to achieve that. In order to adapt the supercharger for the engine, the important design points are below: It was found that intake air blow-by gas at combustion chamber is increased in low engine speed. To improve that, the valve overlap angle was changed to adopt supercharged engine and improve effective compression ratio. Typically the racing engine demands maximum torque for performance but that does not imply that the air fuel ratio should be rich than theoretical. The point is the maximum torque of the engine is proportional to the amount of air intake. Therefore, supercharged engine is possible to increase the supercharging pressure for bigger torque.

Fuel economy improvement has been one of the most important challenges for the automotive industry, and the oil and additive industries. The automotive, oil, and additive industries including related organizations such as SAE, ASTM, and testing laboratories have made significant efforts to develop not only engine oil technologies but also engine oil standards over decades. The API S category and ILSAC engine oil standard are well known and widely used engine oil specifications [1] [2]. The development of an engine oil standard has important roles to ensure the quality of engine oils in the market and encourage industries to improve the engine oil performance periodically. However, the progress of technology advancement can go faster than the revision of engine oil standard. An introduction of new viscosity grades, SAE 0W-16 and 5W-16 is one good example. The 16 grade was added into the SAE J300 standard that defines viscosity grades for engine oils in April 2013 [3].

Contribution to carbon neutrality is one of the most important challenges for the automotive industry. Though CO2 emission has been reduced through electrification, internal combustion engines equipped in vehicles such as Hybrid Electric Vehicle (HEV) and Plug-in Hybrid Electric Vehicle (PHEV) are still necessary for the foreseeable future, and continuous efforts to improve fuel economy are demanded. To improve powertrain thermal efficiency, direct-injection turbocharged gasoline engines have been widely utilized in recent years. Super lean-burn combustion engine has been being researched as the next generation of turbocharged gasoline engines. It is known that an increase of the boost pressure causes deposit formation, which decrease the turbocharger efficiency, in the turbocharger compressor housing. To avoid the efficiency loss due to deposit, air temperature at compressor outlet has to be limited low.

Abnormal combustion referred to as Low Speed Pre-Ignition (LSPI) may restrict low speed torque improvements in turbocharged Direct Injection (DI) - Spark Ignition (SI) Engines. Recent investigations have reported that the auto-ignition of an engine oil droplet from the piston crevice in the combustion chamber may cause unexpected and random LSPI. This study shows that engine oil formulations have significant effects on LSPI. We found that the spontaneous ignition temperature of engine oil, as determined using High-Pressure Differential Scanning Calorimetry (HP-DSC) correlates with LSPI frequency in a prototype turbocharged DI-SI engine. Based on these findings, we believe that the oxidation reaction of the oil is very important factor to the LSPI. Our test data, using a prototype engine, shows both preventative and contributory effects of base oil and metal-based engine oil additives.

As one of spark ignition (SI) engine solutions to improve fuel economy while maintaining drivability, concept of combing turbocharging and direct injection (DI) fuel injection system with engine down-sizing has increased its application in the market. Abnormal combustion phenomena referred to as Low Speed Pre-Ignition (LSPI) has been recognized as potential restriction to improve low speed engine torque that contributes fuel economy improvement. As reported in the part 1 [1], the study showed that engine oil composition had significant influence on the frequency of LSPI in both preventive and contributory effects. Further investigation was conducted to evaluate engine oil formulation variables and other factors that may have influences on the LSPI, such as engine oil degradation. Engine test that consisted of 2 phases was designed in order to confirm the correlation between LSPI frequency and engine oil degradation.

Temperature distribution as the flame propagated and contacted to the wall of the combustion chamber was measured by real-time holographic interference method, which mainly consisted of an argon-ion laser and a high-speed video camera. The experiment was done with a constant volume chamber and propane-air mixture with several kinds of equivalence ratios. From the experimental results, it can be found that the temperature distribution outside the zone from the surface of the combustion chamber to 0.1mm distance could be measured by counting the number of the interference fringes, but couldn't within this zone because of lacking in the resolution of the used optical system. The experimental results show that the temperature distribution when the heat flux on the wall increases rapidly and when the heat flux shows the maximum value are quite different by the equivalence ratio.

Turbocharged downsized gasoline engines have been widely used in the market as one of the measures to improve fuel economy. Coking phenomena in the lubricating circuit of the turbocharger unit is a well-known issue that may affect turbocharger efficiency and durability. Laboratory rig test such as ASTM D6335 (TEOST 33C) has been used to predict this phenomenon as a part of engine oil performance requirements. On the other hand, laboratory tests sometimes have difficulty reproducing the actual mechanism of coking caused by engine oil degradation. Accumulation of insoluble material is one of the important gasoline engine oil degradation modes. The influence of temperature and insoluble concentration were investigated based on actual used engine oils collected in the field.

A fired fuel economy engine test procedure developed by Toyota was proposed to be a new JASO test procedure. Under the JASO Task Force, the fired fuel economy engine test working group was formed. Four test laboratories from oil and additive industries in Japan participated in the JASO Round Robin matrix to evaluate the repeatability and the reproducibility with four candidate reference oils. These candidate reference oils include two viscosity grades and two additive technologies that represent fuel economy engine oil technologies in the Japanese market. The project was successfully completed and the procedure was proposed to be a part of the new JASO GLV-1 engine oil standard.

This paper focuses on the fuel contribution to crankcase engine oil degradation in gasoline fueled engines in view of insoluble formation. The polymerization of degraded fuel is responsible for the formation of insoluble which is considered as a possible cause of low temperature sludge in severe vehicle operating conditions. The main objective of the study is to understand the mechanism of formation of partially oxidized compounds from fuel during the combustion process, before their accumulation in the crankcase oil. A numerical method has been established to calculate the formation of partially oxidized compounds in spark ignition engines directly, by using 3D CFD. To further enable the possibility of running a large number of simulations with a realistic turn-around time, a coupled approach of 3D CFD (with simplified chemical mechanism) and 0D Kinetics (with full chemical mechanism) is proposed here.

The ASTM Sequence VIB is the new fuel economy standard for ILSAC GF-3. The new test pushes the bounds of current engine oil technology. With concerns over Corporate Average Fuel Economy (CAFE) targets, the auto manufacturers have been strong advocates of the Sequence VIB. This paper describes findings of some of fuel economy studies for GF-3. The Sequence VIB is a significant step relative to the past Sequence VIA test in requirements for friction control. Stage-by-stage analysis indicates a shift to a higher degree of “mixed” lubrication response in the Sequence VIB relative to the Sequence VIA, 35 % versus 11 %, making both optimized friction modification and viscosity control necessary for obtaining high levels of fuel economy for GF-3. Viscometric contributions are controlled by both the (high temperature - high temperature) HTHS and basestock viscosity of the oil. Minimizing these viscometric measurements leads to improved fuel economy.