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Since the sizes of the flywheel and clutch have been enlarged due to downsizing of diesel engines, the mass and moment of inertia at the crankshaft rear end have increased. Consequently, the serious bending stresses have appeared in the crankshaft rear. This paper describes the characteristics of those serious bending stresses, based on the mechanism for whirl resonance. The whirl resonance is largely impacted by the mass of the flywheel and clutch and by the distance from the crank-journal center of the rear end to the center of gravity of the flywheel and clutch.

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.

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.

To check sharply increasing traffic accident casualties, activities have been underway to analyze accidents and develop safety equipment Automobile makers have placed a great emphasis on improving safety in collision. In this situation, a new side impact standard was introduced in FMVSS 214 in October 1990 and will be applied to passenger cars in 1993 model year. The standard requires an additional full scale dynamic test in which an aluminum honeycomb moving deformable barrier (MDB) simulating the front end of a car is crashed at 33.5 mph into the side of a standstill car at an angle of 27 degrees. The Side impact Dummy's (SID) Thoracic Trauma index (TTI(d)), which is the average of the maximum rib acceleration and the maximum lower spine acceleration, is limited to 90 g's for a 2-door passenger car and 85 g's for a 4-door car. The dummy's pelvic maximum acceleration must remain no greater than 130 g's for both types of cars.

A numerical analysis method is developed for predicting the pressure fluctuations on the front side window surface, aiming at the elucidation of the external aerodynamic flow structure about the front pillar of a road vehicle. The simulated results are assessed by comparison with the acoustic theory and reveal fairly well the dependence of the predicted surface pressure fluctuations upon the vehicle cruising speed with the sixth power law. The features of three dimensional vortical flow are clarified from the analysis of the simulated results, indicating the strong relationship between the vortical formation and the external pressure fluctuations on the front side window surface. The external pressure fluctuations seem to be strongly related to the vortex breakdown during its interaction with the front side window and the roof-side window junction.

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.

Vibration behavior of a crankshaft in operation is complicated and difficult to simulate because of oil effects on journals, coupled vibration of crankshaft system parts, combustion and inertia acting on the crankshaft. Particularly, the stiffness and damping of oil film vary with crank angles and thus the numerical analysis must deal with nonlinear vibration. This oil film effects also diversify the vibration modes of the crankshat; the vibration modes in an actual operation differs from that in statically experiment modal analysis. This paper describes a new method developed by the author to analyses, predict, and reduce noise and vibration using several techniques including numerical simulation, finite element method, Sommerfeld concept on oil film effects, and modal frequency response.

Equations of motion with six degrees of freedom are composed of detailed dimensions of vehicle, suspension, steering and tire, which must be determined at the designing stage. Particularly, in the dyamics of suspension system, the hypothesis of fixed roll axis are excluded. And, instead, the effect of side force which affects rolling and vertical motion of the vehicle is introduced on the basis of geometrical variation of the tire's contact points. In addition, a number of equations including the cornering force of tire are treated in nonlinear method, with the effect of driving and braking forces being taken into account at the same time. This analysis has enabled strict interpretation of cornering characteristics. However this article is devoted mainly to the analysis of various phenomena which take place in critical situations responsible for accidents in cornering, resultant from spin-out, drift-out, wheel-lift (jack-up) and roll-over.

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.