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Toyota Motor Corporation has developed the new compact-class hybrid vehicle (HV). This vehicle incorporates Toyota Hybrid System II (THS-II) to improve fuel efficiency. For this system we have developed a new power control unit (PCU) that features size reduction, light weight, and high efficiency. We have also improved the ability to mass produce these units with the expectation of rapid popularization of HV. The PCU, which plays an important role in THS-II, is our main focus in this paper. Its development is described.

Automotive engines are regularly utilized in the material handling market where LPG is often the primary fuel used. When compared to gasoline, the use of gaseous fuels (LPG and CNG) as well as alcohol based fuels, often result in significant increases in valve seat insert (VSI) and valve face wear. This phenomenon is widely recognized and the engine manufacturer is tasked to identify and incorporate appropriate valvetrain material and design features that can meet the ever increasing life expectations of the end-user. Alternate materials are often developed based on laboratory testing – testing that may not represent real world usage. The ultimate goal of the product engineer is to utilize accelerated lab test procedures that can be correlated to field life and field failure mechanisms, and then select appropriate materials/design features that meet the targeted life requirements.

Engine-out HC emissions from a PFI spark ignition engine were measured using a gas chromatograph and a flame ionization detector (FID). Two port fuel injectors were used respectively for ethanol and gasoline so that the delivered fuel was comprised of 0, 25, 50, 75 and 100% (by volume) of ethanol. Tests were run at 1.5, 3.8 and 7.5 bar NIMEP and two speeds (1500 and 2500 rpm). The main species identified with pure gasoline were partial reaction products (e.g. methane and ethyne) and aromatics, whereas with ethanol/gasoline mixtures, substantial amounts of ethanol and acetaldehyde were detected. Indeed, using pure ethanol, 74% of total HC moles were oxygenates. In addition, the molar ratio of ethanol to acetaldehyde was determined to be 5.5 to 1. The amount (as mole fraction of total HC moles) of exhaust aromatics decreased linearly with increasing ethanol in the fuel, while oxygenate species correspondingly increased.

Ash, primarily derived from diesel engine lubricants, accumulates in diesel particulate filters directly affecting the filter's pressure drop sensitivity to soot accumulation, thus impacting regeneration frequency and fuel economy. After approximately 33,000 miles of equivalent on-road aging, ash comprises more than half of the material accumulated in a typical cordierite filter. Ash accumulation reduces the effective filtration area, resulting in higher local soot loads toward the front of the filter. At a typical ash cleaning interval of 150,000 miles, ash more than doubles the filter's pressure drop sensitivity to soot, in addition to raising the pressure drop level itself. In order to evaluate the effects of lubricant-derived ash on DPF pressure drop performance, a novel accelerated ash loading system was employed to generate the ash and load the DPFs under carefully-controlled exhaust conditions.

Mechanisms of NH₃ generation using LNT-like catalysts have been studied in a bench reactor over a wide range of temperatures, flow rates, reformer catalyst types and synthetic exhaust-gas compositions. The experiments showed that the on board production of sufficient quantities of ammonia on board for SCR operation appeared feasible, and the results identified the range of conditions for the efficient generation of ammonia. In addition, the effects of reformer catalysts using the water-gas-shift reaction as an in-situ source of the required hydrogen for the reactions are also illustrated. Computations of the NH₃ and NOx kinetics have also been carried out and are presented. Design and impregnation of the SCR catalyst in proximity to the ammonia source is the next logical step. A heated synthetic-exhaust gas flow bench was used for the experiments under carefully controlled simulated exhaust compositions.

Ash accumulation in diesel particulate filters, mostly from essential lubricant additives, decreases the filter's soot storage capacity, adversely affects fuel economy, and negatively impacts the filter's service life. While the adverse effects of ash accumulation on DPF performance are well known, the underlying mechanisms controlling these effects are not. To address these issues, results of detailed measurements with specially formulated lubricants, correlating ash properties to individual lubricant additives and their effects on DPF pressure drop, are presented. Investigations using the specially-formulated lubricants showed ash consisting primarily of calcium sulfates to exhibit significantly increased flow resistance as opposed to ash primarily composed of zinc phosphates. Furthermore, ash accumulated along the filer walls was found to be packed approximately 25% denser than ash accumulated in the channel end-plugs.

The field of automotive engineering has devoted much research to reduce fuel consumption to attain sustainable energy usage. Friction reductions in powertrain components can improve engine fuel economy. Quantitative accounting of friction is complex because it is affected by many physical aspects such as oil viscosity, temperature, surface roughness and component rotation speed. The purpose of this paper is two-fold: first, to develop a useful tool for evaluating the friction in engine and accessories based on test data; second, to exercise the tool to evaluate the fuel economy gain in a drive cycle for several friction reduction technologies.

Further fuel economy improvement of the internal combustion engine is indispensable for CO2 reduction in order to cope with serious global environmental problems. Although lowering the viscosity of engine oil is an effective way to improve fuel economy, it may reduce the wear resistance. Therefore, it is important to achieve both improved fuel economy and reliability. We have developed new 0W- 8 engine oil of ultra-low viscosity and achieved an improvement in fuel economy by 0.8% compared to the commercial 0W-16 engine oil. For this new oil, we reduced the friction coefficient under boundary lubrication regime by applying an oil film former and calcium borate detergent. The film former increased the oil film thickness without increasing the oil viscosity. The calcium borate detergent enhanced the friction reduction effect of molybdenum dithiocarbamate (MoDTC).

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.

It has been required recently that diesel engines for passenger cars meet various requirements, such as low noise, low fuel consumption, low emissions and high power. The key to improve the noise is to reduce a combustion noise known as “Diesel knock noise”. Conventional approaches to reduce the diesel knock are decreasing combustion excitation force due to pilot/pre fuel injection, adding ribs to engine blocks or improving noise transfer characteristics by using insulation covers. However, these approaches have negative effects, such as deterioration in fuel economy and increase in cost/weight. Therefore, modification of engine structures is required to reduce it. We analyzed noise transfer paths from a piston, a connecting rod, a crank shaft to an engine block and vibration behavior during engine operation experimentally, and identified that piston resonance was a noise source.

There is increasing demand for highly functional diesel engine turbochargers capable of meeting Euro 6 emissions regulations while improving dynamic performance and fuel economy. However, since these requirements cannot be easily satisfied through refinements of existing technology, Toyota Motor Corporation has developed the new D-series turbocharger for initial installation in its GD diesel engine. The higher efficiency and wider operation range of the new turbocharger enabled the amount of the turbine flow capacity to be reduced by 30%, while helping to improve dynamic response and fuel economy. The mechanism causing the generation of fuel deposits in the fuel injection system upstream of the turbocharger, which was adopted for compliance with emissions regulations, was analyzed and fundamental countermeasures were applied. The result is a new highly functional turbocharger with greatly enhanced reliability.

Plugin hybrid electric vehicles (PHEVs) have several attractive features in terms of reduction of greenhouse gas (GHG) emissions. Compared to conventional vehicles (CVs) that only have an internal combustion engine (ICE), PHEVs have better energy efficiency like regular hybrids (HEVs), allow for electrifying an appreciable portion of traveled miles, and have no range anxiety issues like battery-only electric vehicles (BEVs). However, in terms of criteria emissions (e.g., NOx, NMOG, HC), it is unclear if PHEVs are any better than HEVs or CVs. Unlike GHG emissions, criteria emissions are not continuously emitted in proportional quantities to fossil fuel consumption. Rather, the amount and type of criteria emissions is a rather complex function of many factors, including type of fuel, ICE temperature, speed and torque, catalyst temperature, as well as the ICE controls (e.g., fuel-to-air ratio, valve and ignition timing).

An experimental study on reducing aerodynamic drag and improving fuel economy through vehicle platooning was conducted to develop an Intelligent Transport System (ITS) with good fuel economy of the entire vehicle-based transportation society. The objectives of the present study are to achieve a simple and quick approach to estimating the aerodynamic drag reduction rates of vehicle platooning. This paper reports the prediction formula, including the conditions of various types of vehicles in multiple-vehicle platooning, based on the power law of a free turbulent axisymmetric wake and on-road experimental results. Note, the prediction formula in this study does not fully include the effect of various type of wake deficit patterns due to rear shape of vehicle and atmospheric wind. Therefore, continuous study is needed to examine the applicable limit.

The use of hybrid, fuel cell electric, and pure electric vehicles is on the increase as part of measures to help reduce exhaust gas emissions and to help resolve energy issues. These vehicles use regenerative-friction brake coordination technology, which requires a braking system that can accurately control the hydraulic brakes in response to small changes in regenerative braking. At the same time, the spread of collision avoidance support technology is progressing at a rapid pace along with a growing awareness of vehicle safety. This technology requires braking systems that can apply a large braking force in a short time. Although brake systems that have both accurate hydraulic control and large braking force have been developed in the past, simplification is required to promote further adoption.

Improving vehicle fuel economy is a central part of efforts toward achieving a sustainable society, and an effective way of 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 vehicles and conventional vehicles in recent years. Cooled EGR has the potential to achieve further lower fuel consumption if the EGR ratio can be increased. Fast combustion is an important and effective way for expanding the EGR ratio. The engine combustion enhancement can be categorized into measures to improve ignition characteristics and methods to promote flame propagation.

The increasing use of gasoline direct injection (GDI) engines coupled with the implementation of new particulate matter (PM) and particle number (PN) emissions regulations requires new emissions control strategies. Gasoline particulate filters (GPFs) present one approach to reduce particle emissions. Although primarily composed of combustible material which may be removed through oxidation, particle also contains incombustible components or ash. Over the service life of the filter the accumulation of ash causes an increase in exhaust backpressure, and limits the useful life of the GPF. This study utilized an accelerated aging system to generate elevated ash levels by injecting lubricant oil with the gasoline fuel into a burner system. GPFs were aged to a series of levels representing filter life up to 150,000 miles (240,000 km). The impact of ash on the filter pressure drop and on its sensitivity to soot accumulation was investigated at specific ash levels.

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].

Fuel consumption and CO2 emission regulations for vehicles, such as the Zero Emission Vehicle (ZEV) Regulation, motivate renewable energy technologies in the automotive industry. Therefore, the automotive industry is focused on adopting solar charging systems. Some vehicles have adopted solar energy to power the ventilation system, but these vehicles do not use solar energy to power the drivetrain. One important issue facing the design of solar charging systems is the low power generated by solar panels. Compared to solar panels for residential use, solar panels for vehicles can’t generate as much power because of size and weight limitations. Also, the power generated by solar panels can be extremely affected depending on differences in solar radiation among the cells. Therefore, Toyota has developed a solar charging system that can use solar energy for driving the Prius PHV. This system can efficiently charge the hybrid battery with the low power generated by the solar panel.

The gasoline direct injection (GDI) engine particulate emission sources are assessed under cold start conditions: the fast idle and speed/load combinations representative of the 1st acceleration in the US FTP. The focus is on the accumulation mode particle number (PN) emission. The sources are non-fuel, combustion of the premixed charge, and liquid fuel film. The non-fuel emissions are measured by operating the engine with premixed methane/air or hydrogen/air. Then the PN level is substantially lower than what is obtained with normal GDI operation; thus non-fuel contribution to PN is small. When operating with stoichiometric premixed gasoline/air, the PN level is comparable to the non-fuel level; thus premixed-stoichiometric mixture combustion does not significantly generate particulates. For fuel rich premixed gasoline/air, PN increases dramatically when lambda is less than 0.7 to 0.8.

To meet future particle mass and particle number standards, gasoline vehicles may require particle control, either by way of an exhaust gas filter and/or engine modifications. Soot levels for gasoline engines are much lower than diesel engines; however, non-combustible material (ash) will be collected that can potentially cause increased backpressure, reduced power, and lower fuel economy. The purpose of this work was to examine the ash loading of gasoline particle filters (GPFs) during rapid aging cycles and at real time low mileages, and compare the filter performances to both fresh and very high mileage filters. Current rapid aging cycles for gasoline exhaust systems are designed to degrade the three-way catalyst washcoat both hydrothermally and chemically to represent full useful life catalysts. The ash generated during rapid aging was low in quantity although similar in quality to real time ash. Filters were also examined after a low mileage break-in of approximately 3000 km.