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For reduction of fuel consumption, a new device “Water Jacket Spacer” which improves temperature distribution of a cylinder block bore wall was developed. In the case of a conventional cylinder block, coolant flow concentrates at the bottom and middle region of the water jacket. While temperature of the upper bore wall is high (due to high-temperature combustion gas) the temperature of the lower bore wall is low, since its only function is to support the piston. When the developed spacer is inserted into a water jacket, the coolant flow concentrates at the upper part of the jacket. As a result, cooling ability to the upper bore wall was improved and temperature of lower bore wall was increased, thereby reducing fuel consumption.

It was important for predicting wall heat flux to apply wall heat transfer model by taking into account of the behavior of turbulent kinetic energy and density change in wall boundary layer. Although energy equation base wall heat transfer model satisfied above requirements, local physical amounts such as turbulent kinetic energy in near wall region should be applied. In this study, in order to predict wall heat transfer by zero dimensional analysis, how to express wall heat transfer by using mean physical amounts in engine combustion chamber was considered by experimental and numerical approaches.

Phosphor thermometry was used during fuel injection in an optical engine with the glass piston of reentrant type. SiO2 coated phosphor particle was used for the gas-phase temperature measurements, which gave much less background signal. The measurements were performed in motored mode, in combustion mode with injection of n-heptane and in non-combustion mode with injection of iso-octane. In the beginning of injection period, the mean temperature of each injection cases was lower than that of the motored case, and temperature of iso-octane injection cases was even lower than that of n-heptane injection cases. This indicates, even if vaporization effect seemed to be the same at both injection cases, the effect of temperature decrease changed due to the chemical reaction effect for the n-heptane cases. Chemical reaction seems to be initiated outside of the fuel liquid spray and the position was moving towards the fuel rich area as the time proceeds.

The renewed platform of the upcoming flagship front-engine, rear-wheel drive (FR) vehicles demands high levels of driving performance, fuel efficiency and noise-vibration performance. The newly developed driveline system must balance these conflicting performance attributes by adopting new technologies. This article focuses on several technologies that were needed in order to meet the demand for noise-vibration performance and fuel efficiency. For noise-vibration performance, this article will focus on propeller shaft low frequency noise (booming noise). This noise level is determined by the propeller shaft’s excitation force and the sensitivity of differential mounting system. In regards to the propeller shaft’s excitation force, the contribution of the axial excitation force was clarified. This excitation force was decreased by adopting a double offset joint (DOJ) as the propeller shaft’s second joint and low stiffness rubber couplings as the first and third joints.

New engine controls have been developed for the turbocharged Lexus NX200t to improve driving power by reducing engine torque output lag. Drive power management functions have been centralized in an integrated drive power control system. The newly developed controls minimize the potential reduction in drivability associated with the adoption of a turbocharged engine while improving fuel efficiency. General driveability issues commonly associated with a turbocharged engine include sudden increases in drive power due to the response lag of the turbocharger, and higher shifting frequencies if this response lag triggers a disturbed accelerator operation pattern by the driver. The developed technologies detect and control sudden increases in drive power to create the optimum drive power map, and reduce unnecessary shifts even if the driver's accelerator operation is disturbed.

Newly developed 2VZ-FE engine for CAMRY is a 2.5-liter water cooled and V-type 6-cylinder engine exported from TOYOTA for the first time. This engine has the TOYOTA original 4-valve DOHC system. That is, exhaust camshafts driven by intake camshafts using scissors gears. By its compact configuration with the gear driven camshafts, this V-type 6-cylinder engine is mounted on a front-wheel-drive vehicle which originally had an in-line 4-cylinder engine. By increasing IVZ-FE engine displacement (for domestic), compact pentroof-type combustion chambers, optimum air-fuel ratio and ignition timing by TCCS (TOYOTA Computer Controlled System) and other technologies, a high performance 153HP/5600rpm and a large torque 155ft·lbs/4400rpm have been achieved with a low fuel consumption.

1 Recently, demand for small-bore compact vehicle engines has been increasing from the standpoint of further reducing CO2 emissions. The generalization and formulation of combustion processes, including those related to emissions formation, based on a certain similarity of physical phenomena regardless of engine size, would be extremely beneficial for the unification of development processes for various sizes of engines. The objective of this study is to clarify what constraints are necessary for engine/nozzle specifications and injection conditions to achieve the same combustion characteristics (such as heat release rate and emissions) in diesel engines with different bore sizes.

To comply with increasingly strict emission regulations, diesel vehicles are equipped with Diesel Particulate Filters (DPF) to capture fine particulate matter (PM) from exhaust gas. However, due to the limited capacity of DPF to capture soot, periodic regeneration processing is required to burn it off. The ash created by metal-based additives in engine oil accumulates in DPF, leading to issues such as increased regeneration frequency and decreased fuel efficiency. To solve this problem, researchers have developed diesel engine oil with reduced ash content. However, the authors are taking it a step further and developing a diesel engine oil without metal-based detergents and anti-wear additives, for even more significant environmental impact reduction. This paper describes the development of an ashless engine oil with DH-2 performance, the effects of the developed engine oil on DPF, and the results of engine and actual field tests.

The engine in the new fourth generation Prius carries over the same basic structure as the 2ZR-FXE used in the third generation and incorporates various refinements to enhance fuel efficiency. Called the ESTEC 2ZR-FXE, the new engine incorporates various fuel efficient technologies to improve combustion characteristics, knocking, and heat management, while also reducing friction. As a result of this meticulous approach to enhancing fuel efficiency, the new engine is the first gasoline engine in the world to achieve a maximum thermal efficiency of 40%. This paper describes the fuel efficient technologies incorporated into this engine.

Methylcyclopentadienyl manganese tricarbonyl (MMT) is used as an octane-enhancing metallic additive for unleaded gasoline which can prevent engine knock by proactive reaction with the hydrocarbon free radicals before starting the auto-ignition of hydrocarbons. However it has been pointed out that MMT causes automotive catalysts clogging and spark plug severely fouling. Therefore, many countries have fuel standards that prohibit or limit the usage of MMT. Nevertheless, some countries still use MMT as there are no restrictions imposed by fuel standards. As mentioned in several papers, metallic additives of engine oil such as calcium cause an abnormal combustion phenomenon called low-speed pre-ignition (LSPI) in turbocharged spark ignition engines. In contrast, the effect of metallic additives of gasoline such as MMT on LSPI has not been studied.

Recently, deposition of ash derived from engine oil on the surface of a diesel particle filter (DPF) has been reported to worsen the performance of the DPF. It is generally known that phosphorus in engine oil is adsorbed on the surface of an automotive exhaust catalyst and reduces the performance of the catalyst. Thus, the amounts of ash and phosphorus in engine oil have been decreased. We have developed a non-phosphorus and non-ash engine oil (NPNA) that does not contain metal-based detergents and zinc dialkyldithiophosphate (ZnDTP). We performed a performance test for NPNA using an actual engine and reported that the piston detergency and anti-wear performance of NPNA were sufficiently high. However, the piston detergency of NPNA required further improvement when engine running conditions were more severe.

In order to clarify the relationship between the chemical structure of PAG (polyalkylene glycol) and the performance characteristics as the refrigeration lubricants used for HFC134a, performance tests were conducted using PAGs with different end groups and alkylene oxide chains in the presence of HFC134a. Newly developed dimethyl ether capped PAGs having more than 70 mol.% PO (propylene oxide) to less than 30 mol.% EO (ethylene oxide) as a monomer ratio were the most preferable of all PAGs tested. The refrigeration lubricants using these PAGs have been successfully introduced into the market for mobile air conditioning systems with refrigerant HFC134a.

In order to achieve the highest power output and lowest fuel consumption for the rotary engine in endurance race such as Le Mans, two types of lubricating oils were developed by conducting a single - rotor engine test at the rotational speed of 7500 rpm under full load. One was the engine oil for the lubrication of the combustion chamber. The other was a so - called system oil for lubrication of the engine system outside the combustion chamber. The conclusions obtained from the development are as follows: 1) Engine oil for the combustion chamber The engine oil greatly influences spitback phenomenon1) which can cause rotary engine trouble in an endurance race. The spitback phenomenon is decreased by the decrease of carbonaceous deposit and ash in the apex seal grooves.

An investigation was conducted into pressure pulsation in the exhaust port, which greatly affects volumetric efficiency and engine performance. From experiments using a single blow-down generator, it was established that the amplitude of the pressure pulsation increases as the manifold branch is lengthened and that large negative pressure synchronized with the timing of valve overlap can be obtained if a proper branch length is used. The performance of a 2ℓ test engine was optimized by varying the length of both the manifold branches and front pipe forks. It was found that whereas front pipe fork length affects engine performance over only a narrow range of engine speed, optimizing manifold branch length results in a considerable improvement over a wide engine speed range. In the course of optimizing the exhaust pipe manifold length of this two-degree-of-freedom exhaust system, abnormal exhaust noises were emitted at specific engine speeds during deceleration.

In order to determine the main factors causing the mileage-related increase in formaldehyde emission from methanol-fueled vehicles, mileage was accumulated on three types of vehicle, each of which had a different air-fuel calibration system. From exhaust emission data obtained during and after the mileage accumulation, it was found that lean burn operation resulted in by far the highest formaldehyde emission increase. An investigation into the reason for the rise in engine-out formaldehyde emission revealed that deposits in the combustion chamber emanating from the lubricating oil promotes formaldehyde formation. Furthermore it was learnt that an increase in engine-out NOx emissions promotes partial oxidation of unburned methanol in the catalyst, leading to a significant increase in catalyst-out formaldehyde emission.

1 Fuel savings by engine oil have been requested for two-wheeled vehicles from the viewpoint of environmental issues. In four-wheeled vehicles, reduction of oil viscosity and addition of friction modifiers have been effective in improving fuel efficiency. However, direct application of engine oil for four-wheeled vehicles to two-wheeled vehicles is difficult. In a four-cycle two-wheeled vehicle, the transmission, gears, and a wet clutch system are imbedded within the engine1). Engine oil must display a remarkable performance as it is required to function as transmission oil and to improve anti-metal fatigue life and clutch performance2), 3). If fuel efficiency is improved by reducing the viscosity of engine oil used in two-wheeled vehicles, the fatigue life tends to worsen. Therefore, reduction in oil viscosity is difficult to achieve.

Modern formulation in a wide variety of lubricants including engine oils and transmission fluids is designed to control friction through film-forming tribochemical reactions induced by the functional additives mixtures. Although many cases on the synergistic or antagonistic effects of additives on friction have been reported, their mechanisms are poorly understood. This study focused on the influences of metallic detergents on tribochemical reactions. We examined the mechanical properties of detergent-containing lubricants confined at a single-asperity contact and their contributions to tribochemical phenomena. We found that detergents enlarged the confinement space required for generating repulsive force and shear resistance. This means that these detergents provide steric effects under nanoconfinement at interfacial contacts.

Small bore diesel engines often adopt a two-valve cylinder head and a non-central injector layout to expand the port flow passage area. This non-central injector layout causes asymmetrical gas flow and fuel distribution, resulting in worse heat losses and a less homogenous fuel-air mixture than an equivalent four-valve cylinder head layout with a central injector. This paper describes the improvement of piston bowl geometry to achieve a more homogeneous gas flow and fuel-air mixture. This concept reduced fuel consumption by 2.5% compared to the original piston bowl geometry, while also reducing NOx emissions by 10%.

Improving vehicle fuel economy is a central part of efforts toward achieving a sustainable society. An effective way for accomplishing this aim is to enhance the engine thermal efficiency. Measures to mitigate knocking and reduce engine cooling heat loss are important aspects of enhancing the engine thermal efficiency. Cooled exhaust gas recirculation (EGR) is regarded as a key technology because it is capable of achieving both of these objectives. For this reason, it has been adopted in a wide range of both hybrid and conventional vehicles in recent years. Toyota has been introducing these technologies as ESTEC (Economy with Superior Thermal Efficient Combustion). Improving cycle-to-cycle variations in combustion, in addition to fast combustion is essential for achieving high engine thermal efficiency.

The reduction of CO2 emissions is one of the most important challenges for the automotive industry to contribute to address global warming. Reducing friction of internal combustion engines (ICEs) is one effective countermeasure to realize this objective. The improvement of engine oil can contribute to reduce fuel consumption by reducing friction between engine parts. Electrification of ICE powertrains increases the overall efficiency of powertrains and reduces the average engine oil temperature during vehicle operation, due to intermittent engine operation. An effective way of reducing engine friction is to lower the viscosity of the engine oil in the low to medium temperature range. This can be accomplished while maintaining viscosity at high temperatures by reducing the base oil viscosity and increasing the viscosity modifier (VM) content to raise the viscosity index (so-called “flat viscosity” concept).