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First of all, we would like to introduce the basic engine mounting layout analysis by the equation of motion and the FEM simulation. For the heavy-duty vehicle, the 4 supporting points engine mounting is basic, but the other types, such as 3 and 5 points also exist. So, we researched what is the best layout to isolate the vibration and support the engine dynamic torque among 11 layout systems by the analyses of eigen value, the frequency response, and the transient response. According to these above studies, when considering all the various criteria, the best engine mounting is the sloping layout. It is the 3rd best for the reduction of engine idling vibration and is the 2nd best against the shock torque.

This paper reports on the analysis of mechanisms concerning the engine exciting force and the rotational couple of forces. Because the new V10 engine has the biggest power and displacement which is 441kw and 30 litters respectively, its exciting force of 2.5th and 5th orders are very large. On the other hand, as the V-bank angular is 80 degrees, the additional 1st order yawing vibration is also occurred by the generation of the rotational couple of forces. So, the optimum design is needed to reduce these vibrations by the frequency response analysis when these forces are added to the engine crank shaft. Finally, the vibration level could be reduced much lower than the lower-powered engine by the optimum design of engine mounting by using the FEM and the adoption of the new mechanism for the cancellation of a rotational couple of force.

This paper shows one example of cooling system, optimized by utilizing computer simulation in the early development stage. First, a numerical simulation is conducted to obtain the air flow rate through engine compartment room by the software “STREAM”. Second, ΔTw are calculated by the software “KULI”, developed by Steyr-Daimler-Puch AG, to evaluate the original cooling system. Third, the optimization of this system is conducted by the design of experiment for cost saving and weight reduction. The test value was well matched with the calculated one and CAE was confirmed to be very helpful for saving the proto-build cost and time period.

This paper describes a method for effectively reducing a level of idling vibration in heavy-duty trucks, which has been the point at issue lately. In this method, the vibration level is significantly reduced by using a full vehicle model, which is made by finite elements, and varying parameters to study effects. In order to achieve high accuracy, engine excitation forces calculated from the measured fluctuation in the flywheel angular velocity are input to the model. An effective use of this method in an early development stage has enabled us to reduce development cost and the lead-time.

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.

Basically, it is recommended that non-linear analysis shoud be used with consideration for friction and etc., when engineers calculate to design the trunnion suspension system for heavy duty trucks. But non-linear analysis was very difficult. so linear analysis per piece parts was conducted under assumed conditions. According to this method, it is difficult to obtain the calculated values matching with experimental values, thus “trial and error” must be repeated consuming much man hours. Recently, accuracy of non-linear analysis has been improved by the progress of the super computer in conjunction with the development of soft-wear such as pre-post or solver. Now, non-linear analysis of the total suspension system was conducted by taking contact and friction between each part into consideration. while at the same time divergence of the solution was prevented by optimum modeling.

In this study, the air suspension is newly applied to the engine mounting layout for getting the significant vibration isolation effect. In this case, the genetic algorithm so called GA is also applied for the optimization of many parameters, calculations of stiffness matrix and inverse stiffness matrix to prevent the coupled vibration of lateral and rolling modes and to obtain the displacement of each mounting point. As a result, inexperienced engineers can easily obtain the optimum engine mounting layout in a minute. By the confirmation test of FEM, the engine lateral vibration level at 25Hz dropped below 1/10 and its effect was significant.

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.