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As the issue of global warming has become more serious, needs for downsizing or weight saving of an engine has been getting stronger, and forces exerted on engine parts, especially force on a crankshaft, have been getting larger and larger. In addition, since a crankshaft is a heavy engine part, needs for saving weight have been getting stronger and stronger. Therefore, determining the mechanism of high stress generation in a crankshaft system is urgently needed. This paper describes the characteristics and mechanism of a severe bending stress caused by the whirl of crankshaft rear end of an inline 6-cylinder medium-duty diesel engine. The authors measured bending stress on the fillets of the crankshaft, and found severe levels of sharp peaks in the stress curves for the crankshaft rear. To figure out why the severe levels of sharp peaks appear, they analyzed and studied the measured data.

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.

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.

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.

Supercharging system is obviously a necessary technology for heavy duty vehicular diesel to meet future stringent emission regulation as well as to improve fuel consumption characteristics. Although the conventional exhaust turbocharger system improves fuel consumption, there are some problems such as having a difficulty in improving starting acceleration and smoke emission characteristic because the response of an exhaust supercharger is not enough. On the other hand, the conventional mechanical supercharging system seems to be a quite effective aid for acceleration ability. However, it does not satisfy demand for low fuel consumption characteristic.

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.

This paper describe the metal-to-ceramic joining method which is important for building ceramic adiabatic engine and deals with the potential of pistons for use for adiabatic ceramic engine. Although various ceramic-to-metal joining methods have been developed, the chemical bonding method such as brazing and diffusion bonding is not only inferior in complex joining process and heat resistance, but also incapable of attaining the bonding strength of 196Mpa required of engineering ceramics. The ceramic-to-metal bonding attained generally by mechanical method such as staking results in the failure of ceramic bonding face due to a strong shearing force accompanied by the plastic deformation of metal. Therefore, the reduction of the shearing force between the ceramic and metal materials and the improvement of plasticity of the metal are necessary.

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.

There are many methods for case hardening such as conventional induction hardening and newly developed electron beam hardening. Electron beam hardening has been adopted in Isuzu and the reliability of engines has been improved. The beam power of the electron beam hardening equipment used was 6 kW. Various conditions of electron beam were scanned across specimens (SCM435H) in order to investigate the influence on hardening properties. As a result, relation between case depth and beam current and relation between case depth and beam scanning time were confirmed. And when the depth exceeded 1 mm, there were cracks in surface melted area. Electron beam hardening was applied to tappets according to the above fundamental experiments, and uniformly hardened layers were obtained. Durability of engines with electron beam hardened tappets was improved twice as much as those with non-hardened tappets.

There is ever an increasing need for weight reduction and high performance of engine (clean smoke and improving fuel economy) To achieve this, recently aluminum castings are used for engine parts such as cylinder heads that construct combustion chamber and are required thermal resistance. This paper describes thermal fatigue tests of aluminum castings that are made under various conditions of cooling rate during solidification, heat treatment, and chemical compositions. It further investigates the influence of material (such as cooling rate, chemical conmposition and heat treatment) and mechanical properties (such as σB, δ, E ) on thermal fatigue life of aluminum castings.

Countour Induction Hardening (CIH) method is in the limelight as a new possible surface refining method for gears as it reduces quenching distortion considerably and increases compressive residual stress. Also, Double Shot Peening (DSP) method, especially its advanced technique of using extensively small shots (less than 100 m) at the secondary peening, enables increased compressive residual stress under the surface of the gears. Therefore, the new Compound Surface Refining Method of using CIH + DSP is expected to give much higher compressive residual stress than the conventional methods. On studying the application of this new method, the authors evaluated their surface-refining characteristics and the fatigue limits.

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.

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.

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.

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.

Engine vibration is a great disadvantage of a V-type six-cylinder engine because ignition does not occur at regular intervals. The engine achieves ignition at regular intervals by having a crank pin offset crankshaft. The shape of the crank pin offset crankshaft is so complex that the location of the crank pin on which bending stress concentrates cannot be obtained easily. This paper reports on the mechanism that generates bending stresses on the crank pin, and discusses the location at which the maximum bending stress is generated with crank pin offset crankshaft.

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.

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.

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.

This paper describes the characteristics and mechanism of crankshaft impact noise that radiates from the cylinder body at full load medium engine speeds, based on the mechanism for axial vibration of crankshaft coupled with torsional vibration of crankshaft.