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Improving idle sound quality as well as reducing idle noise level is increasingly demanded for diesel engines. Therefore, unusual noise occurrence at idle is a serious problem, and the noise must be removed. This paper describes the characteristics and mechanism of ticking noise that is unusual noise radiated from the journal bearing of the camshaft at low idle speeds, based on the mechanism of cavitation in oil film existing between the journal and bearing.

In order to clarify the characteristics of turbulence in diesel combustion, fluctuations of pressure and temperature were measured in a DI diesel engine, and the root mean square value, the auto-correlation coefficient and the power spectrum density of the measured fluctuations were analyzed comparing between the cases with and without pilot injection. The following concluding remarks are obtained. (1) The frequency power spectrum of in-cylinder pressure history is decreased by pilot injection in two frequency ranges from 0.2 to 2.0 kHz and from 2 to 5 kHz. (2) Fluctuation of combustion pressure is dependent on the maximum rate of pressure rise, which is dependent on ignition delay. (3) The maximum RMS of soot temperature fluctuation in the diffusion combustion is dependent on the maximum RMS of pressure fluctuation in the initial combustion. (4) Fluctuation of temperature during diffusion combustion period has the characteristics of isotropic turbulence.

The noise of diesel engines operating at low idle is an important noise evaluation criterion in both commercial vehicles and passenger cars. At low idle, a quiet, pleasant noise is required. Accordingly, unusual noise occurrence at low speed is a serious problem, and the noise must be prevented. In this paper, characteristics of the stick-slip noise, which is an unusual noise that radiates from the oil seal at low idle and the generating mechanism of the stick-slip noise in the six-cylinder-inline diesel engine are discussed. In addition, a method to prevent the stick-slip noise is presented.

This paper offers a brief explanation of Isuzu Transport Auto Control (I-TAC), a system used to accurately collect and control information in-transit. I-TAC was developed as a means to meet needs for transportation by truck.

A torsional damper is attached to a crankshaft to control the torsional vibration of the crankshaft system. However, the damper, which has a rubber part in between a damper mass and a damper hub, possesses a three-dimensional inertia moment and an inertia mass that could excite the crankshaft system. This paper discusses the generating mechanisms of the bending strain on the bolt to fasten the damper hub to the crankshaft, from the measured bolt strains and the measured behavior of the damper mass and the damper hub under the engine operating conditions.

Engine crankshafts have been designed to avoid low-harmonic-order resonant torsional vibration in a commonly-used engine speed range, but the authors have found that, in some engines, especially turbo-charged engines, a significant degree of a low-harmonic-order exciting torque acts on the crankshaft. In these engines, the amplitude of non-resonant low-harmonic-order torsional vibration is almost as large as that of the resonant one. The authors conclude that the 3rd-order non-resonant torsional amplitude is not only significant but also characteristic of the turbo-charged engine in comparison with the naturally-aspirated engine, and recommend that crankshafts on turbo-charged diesel engines should be made stiffer than those on naturally-aspirated engines.

The growing need for improved fuel economy is a global challenge due to continuously tightening environmental regulations targeting lower CO2 emission levels via reduced fuel consumption in vehicles. In order to reach these fuel efficiency targets, it necessitates improvements in vehicle transmission hardware components by applying advanced technologies in design, materials and surface treatments etc., as well as matching lubricant formulations with appropriate additive chemistry. Axle lubricants have a considerable impact on fuel economy. More importantly, they can be tailored to deliver maximum operational efficiency over specific or wide ranges of operating conditions. The proper lubricant technology with well-balanced chemistries can simultaneously realize both fuel economy and hardware protection, which are perceived to have a trade-off relationship.

Every year the trucking industry demands lighter weight and lower cost truck components. But it is very difficult to achieve both these targets. This paper describes the example of a suspension system design which was conducted by computer simulation, so called CAE. The computer simulation by FEM was used completely to decide the detailed shape of each part. This paper also introduces a casting method to strengthen the aluminum alloy cast using high pressure during casting. By using this method, products have a precise metallographic structure. As a result, both the development cost and period were reduced by over the half the time required of the current system and lighter and strong parts were created.

When a heavy duty truck with 2 rear axles is turning a curve at slow speed, a large side bending force to the chassis frame occurres as vehicle turning radius becomes smaller. In the past, the stress produced by side bending forces was little analyzed. By our research work of FEM, side bending stress of heavy duty truck could be analyzed accurately.

GVW 20 ton class cargo trucks were mainly powerd by L6 turbocharged engines ISUZU 6SD1TC and ISUZU 6RB1TC, and this time new 6WA1TC turbocharged engine with intercooler as a successor to 6RB1TC went into production in July 1992. In the recent cargo vehicle market in Japan, demand is increasing for higher out-put power, light weight, long service life, high reliability and low fuel consumption. Under such circumstances special engineering attention was paid to exhaust emissions and noise regulations which are expected to become even stricter in future. The basic engine structure consists of an OHC 4-valve type cylinder head and a ladder frame type cylinder block which satisfies the requirements for the high out-put power, low fuel consumption and light weight. Also, adopted are various variable structures such as a high pressure fuel injection pump with a variable injection timing and rate control device, variable swirl system and variable geometry turbocharger.

Torsional dampers have been attached to engine crankshafts only for the control of the crankshaft torsional vibrations. However, a torsional damper is a mass-spring system of three-dimensions, so the torsional damper could exert some influence on the three-dimensional vibrations of the crankshaft system. Since the inertia ring of the torsional damper has moments of inertia and it rotates with the crankshaft, gyroscopic vibrations of the inertia ring can also be generated. For a V-type ten-cylinder diesel engine (V- 10, ϕ119 × 150), the three-dimensional vibrations of the crankshaft system were calculated by the dynamic stiffness matrix method, taking account of the influence of the gyroscopic vibrations of the inertia ring of the torsional damper. The dynamic bending stresses were measured at the fillets of both the No.1 crank journal and the No.1 crank pin in the No.1 crank throw plane.

Application of alternate fuels to diesel engine is much desired. A new and unique dual-fuel injection system has been developed for high speed automotive diesel engines. This system has two features. One is that alternate fuels such as methanol, ethanol and biomass, are directly inducted into the fuel injection pipe through one-way check valve under pressure, and blended fuels are simultaneously injected into the combustion chamber. The other is that various kinds of fuel can be easily adapted to this system not dependent upon the fuel properties such as viscosity. Using a single cylinder direct injection diesel engine and ethanol as an alternate fuel, injection characteristics and exhaust gas emissions were investigated. The results showed that ethanol could replace up to 50% of diesel fuel while keeping the normal engine operating stability. A better fuel economy was also obtained by applying both higher compression ratio and advanced injection timing.

The P’UP has been on the markets worldwide since 1972, both in Japan and overseas, including for the U.S., in which case, with model designation as the Chevrolet LUV. In 1980, for the first time since its market introduction, it was fully remodelled with detail improvements reflected thereon in every aspect. This new model continues to be on the U.S. market as the Chevrolet LUV as it has been, but, beginning from spring of 1981, the similar model has been introduced to the market by the American Isuzu Motors Inc. (AIM) as the Isuzu P’UP. Taking this opportunity, a diesel version has been added to its model lineup. The diesel engine mounted on this version features its 20 to 30% better fuel efficiency over its gasoline counterpart. In the first half of this paper, the engineering concepts of its full remodelling and their onvehicle reflection will be introduced.

A pre-combustion chamber (hot plug) made of the silicon nitride ceramics has been developed. The hot plug constitutes a component of the combustion chamber of swirl chamber diesel engines. And it is subjected to the severest thermal load of all the diesel engine operating components. Unlike metal hot plugs, the ceramic hot plug application requires a unique design approach to meet the ability of the ceramic materials. That is, the soft engine mounting is necessary to avoid the concentraction of mechanical stress resulting from the high Young's Modulus of the ceramic and control of temperature distribution is also required to reduce thermal stress. Due to the heat insulating construction, the ceramic hot plug permits the combustion performance to be improved at a low speed and load, resulting in improved noise, startability, and HC emission. In additional the ceramic hot plugs are already being produced for diesel passenger car.

In order to meet the demands for reduced emissions and improved fuel consumption, a subport-type variable swirl system (Isuzu Variable Electronic Economy Swirl, or IVES) was developed by Isuzu for medium- and heavy-duty direct-injection-type diesel engines. The main characteristics of IVES are: (1) It is simple in structure and only minor changes to the cylinder head are required. (2) Modular design is possible for three different swept volume engines due to the use of a common actuator and sensor. (3) The problem of air flow coefficient drop when swirl is varied has been successfully eliminated.

In fleet uses, heavy-duty trucks with turbo, inter-cooled engines are popular in Japan. These trucks usually experience congested traffic and/or frequent road grade change in expressways. As a result, frequent vehicle speed and engine load fluctuations are observed. This paper describes the typical, on road driving data from the field and presents one sample of engine control optimization for better fuel economy in actual road conditions.

Experiment results were compared with computation analysis results for torsional vibration on a crankshaft system with/without a torsional viscous damper on a six-cylinder in-line type turbocharged diesel engine and a V type ten-cylinder naturally-aspirated diesel engine respectively. At first, the boundary conditions for boundary element method (BEM) model were determined to estimate the torsional stiffness of the crank-throws of the crankshafts. Then, the estimated stiffness was used to calculate the natural frequencies of the torsional vibration without the damper by dynamic stiffness matrix method. As a result, the calculated natural frequencies approximately agreed with the measured ones. Finally, the torsional vibration with the damper was analyzed by using the dynamic stiffness matrix method and complex viscous damping coefficients for the damper. The calculated torsional amplitudes and resonant engine speeds agreed with the experiment results.

This paper describes measurement and calculation method for determining pressure on an engine gasket under the static and dynamic condition. At first, the relationship between the strain of the cylinder liner and the pressure on the gasket was determined. Then the strain of the cylinder liner was measured under the static condition as well as under the dynamic condition. The gasket contact pressure was also calculated by computer using FEM model. The calculation results were compared with the measurement results. Finally, the effects of the combustion pressure and heat on the gasket contact pressure were discussed based on the strains.

A driven turbocharger offers many benefits for internal combustion engines over traditional turbochargers or superchargers. One type of driven turbocharger, a SuperTurbo, is an amalgamation of supercharger, turbocharger, and turbo-compounder all in one device. This is accomplished through the combination of a high-speed traction drive that transfers bi-directional torque between the turbo shaft and a CVT, which then allows for overall ratio control between the turbo and the crankshaft. High efficiency turbine designs become feasible through the removal of overspeed and turbo lag design restrictions. Isuzu recognized the benefits of a driven turbocharger and the two companies have worked to evaluate it against more conventional turbochargers. This paper documents years of simulation, development, and engine testing, with a focus on steady state optimization of a 7.8L diesel engine.

The filtration efficiency of a DPF drops when it suffers a failure such as melting and cracks during regeneration. And then, on-board diagnostics (OBD) device has become needed worldwide to detect a DPF failure. In the development of an OBD soot sensor, evaluation of the sensor demands a portable instrument which can measure the soot concentration for on-board and in-field use. Some of the emission regulations require the in-field emission measurements under normal in-use operation of a vehicle. This study is intended to develop a high sensitivity and high response portable smoke meter for on-board soot measurements and a reference to OBD soot sensors under development. The smoke meter accommodates a 650 nm laser diode, and its principle is based on light extinction in high soot concentration range and backward light scattering for low soot concentration measurement.