Engine and Overall Vehicle Adjustment Taking the Drivability into Account

The adjustment of current engine and vehicle respectively power train concepts requires the evaluation respectively the assessment of the drivability at a very early development stage. The conventional application basically can be divided according to the individual development topics:

Looking at the sequence of the individual topics according to the processing sequence, it can be seen that knowing the drivability to be expected at an early stage means having a substantial advantage during the development as a whole.
As these development tasks cannot be processed separately respectively without repercussions, often there are time consuming and cost-intensive iteration loops. The indicating measurement in the application process has proved to be another tool regarding the optimisation of the customer-relevant development topics vs. the legal provisions in the vehicle. Thus it is obvious to combine measurement values of a drivability assessment system (such as AVL DRIVE™) and IndiCom™ (plus related measurement chain). A common analysis of the measurement variables with the resulting targeted development method with a safe deduction of the following development steps allows for reducing the development effort while simultaneously increasing the quality.

Diversification Through Optimized Dynamical Torque Build-Up in Real Vehicle Operation

AVL DRIVE™ distinguishes between several classes of vehicles and also takes the expectations of the corresponding buyer group with regard to the power train into account. The software enables the user to determine brand-specific, objective properties (Branding) within a class of vehicles.

One example for this is the dynamical torque build-up which is allocated different priorities with regard to the customers’ expectations according to the different classes of vehicles. Using the combination of AVL DRIVE™ and AVL IndiCom™ the torque build-up can be completely optimized within each class while meeting statutory regulations or the demand for vehicles with low fuel consumption. Figure 1 shows the calibration example of a typical application in the test vehicle.

Figure 1: System Overview

One example: The original situation shows anunacceptable tip-in behavior, figure 2. The torque build-up causes the entire power train to vibrate in a way which can be clearly felt by the driver by a strongly modified longitudinal acceleration (“Bonanza effect”). The software AVL DRIVE™ determines the driving performance during tip-in according to pre-set trigger conditions and then evaluates this subjectively negative situation using objective criteria. First, using an additional indicating measurement in the vehicle the combustion processes during the tip-in phase are recorded. Thanks to the joint evaluation of the measuring data using AVL DRIVE™ and IndiCom™ combined the combustion-relevant causes for this unacceptable effect can then be quickly detected.

This evaluation provides the basis for the optimization of the combination of torque build-up (IndiCom™) and power train resonance. This allows the detailed analysis of the individual system reactions and reduces development times and automatically ensures qualitatively better results.

Figure 2: Tip-In with „Bonanza“ Effect

Figure 3: Improved Application Tip-In

Figure 3 shows the improvement. The vehicle's reaction to a tip-in after emission-neutral optimization of torque build-up can clearly be seen, a constant harmonic longitudinal acceleration process with improved vehicle dynamics is obtained.

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