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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 Dual Piston Variable Compression Ratio (VCR) engine has been newly developed. In order to ensure the strength of the Dual Piston, the design guidelines were established. There are two advantages of this design. One is the compactness and the compatibility with a mass production engine block. Another is less power consumption required during compression ratio switching. However, the durability is a challenge for this design because of the impact load during the switching driven by the inertial force of a reciprocating piston. In order to achieve a durable configuration, it was necessary to consider the dynamics of the stress after impact, from analysis of the impacting process during the switching. The analysis of stress and deformation mode was improved in accuracy by using Computer Aided Engineering (CAE) in the designing process.

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.

HCCI combustion can realize low NOx and particulate emissions and high thermal efficiency. Therefore, HCCI combustion has a possibility of many kinds of applications, such as an automotive powertrain, general-purpose engine, motorcycle engine and electric generator. However, the operational range using HCCI combustion in terms of speed and load is restricted because the onset of ignition and the heat release rate cannot be controlled directly. For the extension of the operational range using either an external supercharger or a turbocharger is promising. The objective of this research is to investigate the effect of the intake pressure on the HCCI high load limit and HCCI combustion characteristics with blowdown supercharging (BDSC) system. The intake pressure (Pin) and temperature (Tin) were varied as experimental parameters. The intake pressure was swept from 100 kPa (naturally aspirated) to 200 kPa using an external mechanical supercharger.

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.

The regulations for mobile applications will become stricter in Euro 6 and further emission levels and require the use of active aftertreatment methods for NOX and particulate matter. SCR and LNT have been both used commercially for mobile NOX removal. An alternative system is based on the combination of these two technologies. Developments of catalysts and whole systems as well as final vehicle demonstrations are discussed in this study. The small and full-size catalyst development experiments resulted in PtRh/LNT with optimized noble metal loadings and Cu-SCR catalyst having a high durability and ammonia adsorption capacity. For this study, an aftertreatment system consisting of LNT plus exhaust bypass, passive SCR and engine independent reductant supply by on-board exhaust fuel reforming was developed and investigated. The concept definition considers NOX conversion, CO2 drawback and system complexity.

Multiple-injection strategies are widely used in DI diesel engines. However, the interaction of the injection pulses is not yet fully understood. In this work, a split injection into a combustion vessel is studied by multiple optical imaging diagnostics. The vessel provides quiescent high-temperature, high-pressure ambient conditions. A common-rail injector which is equipped with a three-hole nozzle is used. The spray is visualized by Mie scattering. First and second stage of ignition are probed by formaldehyde laser-induced fluorescence (LIF) and OH* chemiluminescence imaging, respectively. In addition formation of soot is characterized by both laser-induced incandescence (LII) and natural luminosity imaging, showing that low-sooting conditions are established. These qualitative diagnostics yield ensemble-averaged, two-dimensional, time-resolved distributions of the corresponding quantities.

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.

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.

The technology to estimate engine load using the amplitude of crankshaft angular velocity variation during a cycle, which is referred to as “Δω (delta omega)”, in a four-stroke single-cylinder gasoline engine has been established in our former studies. This study was aimed to apply this technology to the spark advance control system for small motorcycles. The cyclic variation of the Δω signal, which affects engine load detection accuracy, was a crucial issue when developing the system. To solve this issue, filtering functions that can cope with various running conditions were incorporated into the computation process that estimates engine loads from Δω signals. In addition, the system made it possible to classify engine load into two levels without a throttle sensor currently used. We have thus successfully developed the new spark advance system that is controlled in accordance with the engine speed and load.

The most challenging part of the engine combustion development is the reduction of pollutants (e.g. CO, THC, NOx, soot, etc.) and CO2 emissions. In order to achieve this goal, new combustion techniques are required, which enable a clean and efficient combustion. For compression ignition engines, combustion rate shaping, which manipulates the injected fuel mass to control the in-cylinder pressure trace and the combustion rate itself, turned out to be a promising opportunity. One possibility to enable this technology is the usage of specially developed rate shaping injectors, which can control the injection rate continuously. A feasible solution with series injectors is the usage of multiple injections to control the injection rate and, therefore, the combustion rate. For the control of the combustion profile, a detailed injector model is required for predicting the amount of injected fuel. Simplified 0D models can easily predict single injection rates with low deviation.

New combustion processes require an understanding of the highly three-dimensional flow field to effectively decrease fuel consumption and pollutant emission. Due to the complex spatial character of the flow the knowledge of the development of the flow in an extended volume is necessary. Previous investigations were able to visualize the discrete three-dimensional flow field through multi-plane stereoscopic PIV. In this study, cycle resolved tomographic particle-image velocimetry measurement have been performed to obtain a fully resolved representation of the three-dimensional flow structures at each instant. The analysis is based on the measurements at 80°, 160°, and 240° after top dead center(atdc) such that the velocity distributions at the intake, the end of the intake, and the compression stroke at an engine speed of 1,500 rpm are discussed in detail.

As a result of the excavation of unconventional sources of natural gas, which has rich reserves, has attracted attention as a fuel for use in natural gas engines for power generation. From the viewpoints of efficient resource utilization and environmental protection, lean burn is an attractive technique for realizing a higher thermal efficiency with lower NOx emissions. However, ignition systems have to be improved for lean-burn operations. Laser ignition, which is expected to serve as an alternative to spark plug ignition, can decrease the heat loss and has no restriction on the ignition location because of the absence of an electrode. Consequently, an extension of the lean-burn limit by laser ignition has been demonstrated. In this study, we investigated the effects of the location and number of laser ignition points on engine performance and exhaust emissions. Laser ignition was also compared with conventional spark plug ignition.

In this article, the development challenges of a fuel cell system are explained using the example of the BREEZE! fuel cell range extender (FC-REX) applied in an FEV Liiona. The FEV Liiona is a battery electric vehicle based on a Fiat 500 developed by FEV. The BREEZE! system is the first applied 30 kW low temperature polymer electrolyte membrane (LT PEM) fuel cell system in the subcompact vehicle class. Due to the highly integrated system approach and dry cathode operation, a compact design of the range extender module with a system power density of 0.45 kW/l can be achieved so that the vehicle interior including trunk remains completely usable. System development for fuel cells significantly influences performance, efficiency, package, durability, and required maintenance effort of a fuel cell electric powertrain. In order to ensure safe and reliable operation, the fuel cell system has to be supplied with sufficient amounts of air, hydrogen, and coolant flows.

The interaction of biofuel sprays from an outward opening hollow cone injector and the flow field inside an internal combustion engine is analyzed by Mie-Scattering Imaging (MSI) and high-speed stereoscopic particle-image velocimetry (stereo-PIV). Two fuels (ethanol and methyl ethyl ketone (MEK)), four injection pressures (50, 100, 150, and 200 bar), three starting points of injection (60°, 277°, and 297° atdc), and two engine speeds (1,500 rpm and 2,000 rpm) define the parameter space of the experiments. The MSI measurements determine the vertical penetration length and the spray cone angle of the ethanol and MEK spray. Stereo-PIV is used to investigate the interaction of the flow field and the ethanol spray after the injection process for a start of injection at 60° atdc. These measurements are compared to stereo-PIV measurements without fuel injection performed in the same engine [19].

A simple method is frequently used to calculate a reciprocating engine’s bearing load from the measured cylinder pressure. However, it has become apparent that engine downsizing and weight reduction cannot be achieved easily if an engine is designed based on the simple method. Because of this, an actual load on a bearing was measured, and the measured load values were compared with a bearing load distribution calculated from cylinder pressure. As a result, it was found that some of actual loads were about half of the calculated ones at certain crank angles. The connecting rod’s elastic deformation was focused on as a factor behind such differences, and the rod’s deformation due to the engine’s explosion load was studied. As a result, it was found that the rod part of the engine’s connecting rod was bent by 0.2 mm and became doglegged. Additional investigation regarding these findings would allow further engine downsizing.

The influence of two oxygenated tailor-made fuels on soot formation and oxidation in an optical single cylinder research diesel engine has been studied. For the investigation a planar laser-induced incandescence (PLII) measurement technique was applied to the engine in order to detect and evaluate the planar soot distribution for the two bio fuels within a laser light sheet. Furthermore the OH* chemiluminescence and broad band soot luminosity was visualized by high speed imaging to compare the ignition and combustion behavior of tested fuels: Two C8 oxygenates, di-n-butylether (DNBE) and 1-octanol. Both fuels have the same molecular formula but differ in their molecular structure. DNBE ignites fast and burns mostly diffusive while 1-octanol has a low cetane number and therefore it has a longer ignition delay but a more homogeneous mixture at time of ignition. The two bio fuels were finally compared to conventional diesel fuel.

According to some papers, the label fuel economy and the actual fuel economy experienced by the customers may exhibit a gap. One of the reasons may stem from the aerodynamic drag variations due to the natural wind. The fuel consumption is measured through bench test under several driving modes by using the road load as input condition. The road load is measured through the coast down test under less wind ambient conditions as determined by each regulation. The present paper aims to analyze the natural wind conditions encountered by the vehicle on public roads and to operate a comparison between the fuel consumptions and the driving energy. In this paper, the driving energy is calculated by the aerodynamic drag from the natural wind specifications and driving conditions. This driving energy and the fuel consumptions show good correlation. The fuel consumption is obtained from the vehicle Engine control unit(ECU) data.