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In the pursuit of a sustainable transportation systems, Toyota is considering a comprehensive approach pursuing multiple advanced technologies to address three primary issues: GHG, Petroleum Use, and Air Quality. Vehicles must be ready for and affordable to the mass market to provide the customer choices to meet their transportation needs whether it is EV's, Hybrids, Plug-In Hybrids or Fuel Cell Hydrogen Hybrids. Our studies have shown that EVs have the potential to provide significant improvements in energy utilization especially combined with other advanced technologies. Toyota believes that a combination of these technolgies will provide complementary solution that enables a sustainable transportation system. Presenter Takehito Yokoo, Toyota Motor Corporation

Currently, two consolidated aftertreatment technologies are available for the reduction of NOx emissions from diesel engines: Urea SCR (Selective Catalytic Reduction) systems and LNT (Lean NOx Trap) systems. Urea SCR technology, which has been widely used for many years at stationary sources, is becoming nowadays an attractive alternative also for light-duty diesel applications. However, SCR systems are much more effective in NOx reduction efficiency at high load operating conditions than light load condition, characterized by lower exhaust gas temperatures.

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.

A dual piston Variable Compression Ratio (VCR) engine has been newly developed. This compact VCR system uses the inertia force and hydraulic pressure accompanying the reciprocating motion of the piston to raise and lower the outer piston and switches the compression ratio in two stages. For the torque characteristic enhancement and the knocking prevention when the compression ratio is being switched, it is necessary to carry out engine controls based on accurate compression ratio judgment. In order to accurately judge compression ratio switching timing, a control system employing the Hidden Markov Model (HMM) was used to analyze vibration generated during the compression ratio switching. Also, in order to realize smooth torque characteristics, an ignition timing control system that separately controls each cylinder and simultaneously performs knocking control was constructed.

A new index U* for evaluating load path dispersion is proposed, using a structural load path analysis method based on the concept of U*, which expresses the connection strength between a load point and an arbitrary point within the structure. U* enables the evaluation of the load path dispersion within the structure by statistical means such as histograms and standard deviations. Different loading conditions are applied to a body structure, and the similarity of the U* distributions is evaluated using the direction cosine and U* 2-dimensional correlation diagrams. It is shown as a result that body structures can be macroscopically grasped by using the U* distribution rather than using the stress distribution. In addition, as an example, the U* distribution of torsion loading condition is shown to comprehensively include characteristics of the U* distribution of other loading conditions.

With the objective of establishing the ultimate steering operation system for drivers, we developed, based on bioengineering considerations, the Twin Lever Steering (TLS) system which mimicks the bi-articular muscles, as shown in Fig. 1 . The bioengineering advantages are as follows: (1) force can be exerted more easily, (2) the steering can be accomplished quickly, (3) the positioning can be done accurately, and (4) the burden on the driver can be reduced (less fatigue). The advantages of the vehicle in terms of its motion are as follows: (1) the line-traceability is improved, (2) the drift control is improved, (3) the lane-change capability is improved, and (4) the lap time and stability are improved. We would like to report on these advantages of the TLS system from a bioengineering standpoint, and also describe the results of some verification test results obtained from vehicles equipped with this new steering system.

Honda has developed a new next-generation 3.5 L V6 gasoline engine using our latest Earth Dreams Technology. The overall design objective for the engine was to reduce CO₂ emissions and provide driving exhilaration. The Earth Dreams Technology concept is to increase fuel economy while reducing emissions. To achieve this and provide an exhilarating driving experience, 3-stage Variable Valve Timing and Lift Electronic Control (VTEC) was combined with the Variable Cylinder Management (VCM) system. This valve train technology in conjunction with Direct Injection (DI), resulted in dramatic improvements in output (a 3.3% increase) and combined mode fuel economy (20% reduction). Helping to achieve Midsize Luxury Sedan level NV, a new mount system was developed to reduce engine vibrations during three-cylinder-mode operation. In this paper, we will explain the 3-stage VTEC with VCM + DI system, friction reducing technology, and the structure and benefit of the new engine mount system.

Using a 109.2 cm3, four-stroke, single-cylinder, two-valve gasoline engine, improvement of fuel economy by extension of lean burn range has been attempted with invented way to intensify tumble flow from a simple mechanical arrangement. With a part of the intake valve was jutted out beyond the perimeter of the cylinder bore, the masking effects from the valve recess on top of the cylinder sleeve created a strong tumble flow, which enabled lean burn at an air fuel ratio leaner than the conventional design by two points. The motorcycle equipped with this engine attained better fuel economy by 5.7% to the base model when measured in Indian Driving Cycle (IDC). The outward-laid intake valve also increased the clearance from the exhaust valve, which enabled use of a large-diameter intake valve to minimize the reduction of maximum power.

Research has been conducted on Controlled Auto-Ignition (CAI) engine with natural gas. CAI engine has the potential to be highly efficient and to produce low emissions. CAI engine is potentially applicable to automobile engine. However due to narrow operating range, CAI engine for automobile engine which require various speed and load in real world operation is still remaining at research level. In comparison some natural gas engines for electricity generation only require continuous operation at constant load. There is possibility of efficiency enhancement by CAI combustion which is running same speed at constant load. Since natural gas is primary consisting of methane (CH4), high auto-ignition temperature is required to occur stable auto-ignition. Usually additional intake heat required to keep stable auto-ignition. To keep high compression temperature, single cylinder natural gas engine with high compression ratio (CR=26) was constructed.

In the automobile industries, weight reduction has been investigated to improve fuel efficiency together with reduction of CO2 emission. In such circumstance, it becomes necessity to make an electric power steering (EPS) more compact and lightweight. In this study, we aimed to have a smaller and lighter EPS gear size by focusing on an impact load caused at steering end. In order to increase the shock absorption energy without increase of stopper bush size, we propose new theory of impact energy absorption by not only spring function but also friction, and a new stopper bush was designed on the basis of the theory. The profile of the new stopper bush is cylinder form with wedge-shaped grooves, and when the new stopper bush is compressed by the end of rack and the gear housing at steering end, it enables to expand the external diameter and produce friction. In this study, we considered the durability in the proposed profile.

This paper will discuss the stress reduction of the worm wheel for an electric power steering (EPS) system. The research discussed in this paper focused on the worm wheel, the EPS component that determines the maximum diameter of the system. If the stress of the worm wheel could be reduced without increasing in size, it would be possible to reduce the size of the worm wheel and EPS system. In order to reduce the stress of the worm wheel, the conventional design method has extended the line-of-action toward outside of the worm wheel to increase the contact ratio of the gears and these method lead to an increase in the outer diameter. In order to address this issue, past research proposes the basic concept to extend line-of-action toward the inside of the worm wheel. And this new meshing theory was named MUB (Meshing Under Base-circle) theory. In this paper, characteristics of meshing of the gear formed by MUB theory are determined in more detail.

With demands for enhanced environmental performance such as fuel economy, the tendency has been to reduce the amount of wind introduced to the engine room to reduce drag. Meanwhile, exhaust gas temperatures are increasing in order to reduce emissions concentrations. As a result, the temperature environments for parts inside the engine room and underfloor parts are becoming harsher, and accurately understanding the temperature environments of parts is crucial in determining Engine room component layout during vehicle development and applying effective thermal countermeasures. Computational fluid dynamics (CFD) are effective for understanding complex phenomena such as heat generation and cooling. However, this paper reports the development of a method for accurately calculating the vehicle temperature distribution through identification from test results.

Designing a lightweight and durable engine is universally important from the standpoints of fuel economy, vehicle dynamics and cost. However, it is challenging to theoretically find an optimal solution which meets both requirements in products such as the cylinder head, to which various thermal loads and mechanical loads are simultaneously applied. In our research, we focused on “non-parametric optimization” and attempted to establish a new design approach derived from the weight reduction of a cylinder head. Our optimization process consists of topology optimization and shape optimization. In the topology optimization process, we explored an optimal structure with the theoretically-highest stiffness in the given design space. This is to provide an efficient structure for pursuing both lightweight and durable characteristics in the subsequent shape optimization process.

In this research, a new wire material made using surface-reforming heat treatment was developed in order to enhance the corrosion fatigue resistance of suspension springs. The aim of surface reforming is to improve hydrogen embrittlement characteristics through grain refinement and to improve crack propagation resistance by partial softening of hardness. The grain refinement method used an α'→γ reversed transformation by rapid short-term heating in repeated induction heating and quenching (R-IHQ) to refine the crystal grain size of SAE 9254 steel spring wire to 4 μm or less. In order to simultaneously improve the fatigue crack propagation characteristics, the possibility of reducing the hardness immediately below the spring surface layer was also examined. By applying contour hardening in the second IHQ cycle, a heat affected zone (HAZ) is obtained immediately below the surface.

The process for setting the marketability targets and achievement methods for automotive interior quietness (as related to air borne noise above 400Hz, considered the high frequency range) was established. With conventional methods it is difficult to disseminate the relationship between the performance of individual parts and the overall vehicle performance. Without new methods, it is difficult to propose detailed specifications for the optimal sound proof packages. In order to make it possible to resolve the individual components performance targets, the interior cavity was divided into a number of sections and the acoustic performance of each section is evaluated separately. This is accomplished by evaluating the acoustical energy level of each separate interior panel with the unit power of the exterior speaker excitation. The applicability of the method was verified by evaluating result against predicted value, using the new method, during actual vehicle operation.

Bio-ethanol is used in many areas of the world as ethanol blended gasoline at low concentrations such as “E10 gasoline”. In this study, a method was examined to effectively use this small amount of ethanol within ethanol blended gasoline to improve thermal efficiency and high-load performance in a high-compression-ratio engine. Ethanol blended gasoline was separated into high-concentration ethanol fuel and gasoline using a fuel separation system employing a membrane. High-ethanol-concentration fuel was selectively used at high-load conditions to suppress knocking. In this system, a method to decrease ethanol consumption is necessary to cover the wide range of engine operation. Lower ethanol consumption could be achieved by Miller-cycle operation because decrease of the effective compression ratio suppresses knocking. However, high-load operation was limited due to the decrease in intake air volume with Miller-cycle operation.

In this study, we developed a simulation method for rough road running condition to reproduce the behaviors of a vehicle body and to precisely estimate the input loads to the frame. We designed the simulation method focusing on a front fork model and a rider model optimized for this type of analysis. In the suspension model development, we conducted detailed measurement of the suspension characteristics on a test bench. Based on the yielded results, the friction force, as well as the spring reaction force and the damping force, was reproduced in the suspension model. The friction of the suspension varies depending on the magnitude of the reaction force associated with bending and this effect was also implemented in the model. Regarding the rider model, the actual behavior of a rider was investigated through the recorded motion video data and used to define the necessary degrees of freedom.

In brake squeal analyses using FE models, minimizing the discrepancies in vibration characteristics between the measurement and the simulation is a key issue for improving its reproducibility. The discrepancies are generally adjusted by the shape parameters and/or material properties applied to the model. However, the discrepancy cannot be easily adjusted, especially, for the vibration characteristic of the disc model of a motorcycle. One of the factors that give a large impact on this discrepancy is a thermal history of the disc. That thermal history includes the one experienced in manufacturing process. In this paper, we examine the effects of residual stress on the natural frequency of motorcycle discs. The residual stress on the disc surface was measured by X-ray stress measurement method. It was followed by an eigenvalue analysis. In this analysis, we developed a unique method in which the residual stress was substituted by thermal stress.

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).

In many cars, ride is less comfortable on smooth roads. This is because when the hysteresis in the suspension components rises steeply, the increase of the equivalent spring constant at small amplitude deteriorates the vibration isolation of the suspension. Therefore suspension components should be designed to prevent a steep rises in hysteresis. Investigating the influence of hysteresis, component models, which can reproduce such hysteresis characteristics, should be installed with model parameters in the vehicle model. Using conventional methods, these parameters can be accurately identified if measurement data is provided; however, it is difficult at the earlier phase of vehicle development. Then, if conflicting performances, such as ride and handling, are to be improved, both should be considered concurrently as early in a phase of vehicle development as possible and the design specifications for suspension components should be determined to satisfy both performances.