Comprehensive Measurement Solution

Application Area of Pressure Based Injection Technology

In the past, different measurement methods were used to examine the mixture formation and combustion in combustion engines. One of the technologies developed for these examinations, the pressure based indicating measurement, has become the standard and today is an integral part of the engine development process.

Robust and precise high pressure and high temperature resistant piezoelectric sensors provide reliable and precise results to analyse the combustion, indicated mean effective pressure, peak pressure, combustion noise and knocking as well as other phenomena. Today, all these values play a critical role when using an existing engine in specific power trains and vehicles, as the steadily increasing performance and the simultaneously stricter exhaust gas and quality standards forces the optimal utilisation of the combustion in all operating points.

Variable valve drive systems, variable intake port geometry, flexible injection systems and advanced combustion concepts provide a large amount of flexibility, but simultaneously result in more complex combustion systems. Can this complexity be solved with the classic indicating?

Optical Analysis Using AVL Visiolution

In addition to classical indicating measurements optical analysis processes are growing more and more important. AVL Visiolution is used for the development of new combustion processes and also increasingly for the optimization of the calibration process and to solve problems quickly and efficiently. AVL offers the system itself and the measuring service as well.

Gas Exchange and Combustion Optimization Using AVL GCA

AVL GCA is based on the same calculation kernel as the extended AVL software for one-dimensional simulation "AVL-BOOST" and provides a simulation model whose system limits or boundary conditions are the measured low pressure indicating curves intake and exhaust. Gas-dynamic effects in the pipe system are taken into account. This approach reduces the calculation time while at the same time considerably increasing the accuracy of the description of in-cylinder processes. With the online implementation at the test bed AVL-GCA enables the user to bring simulation and measurement closer to each other. AVL-GCA can also be used as CONCERTO option in order to be able to conduct supplementary extended analyses.

Analyze Component Stress and Vibration Using IndiCom

Component stress, deformation and vibration in combustion engines are caused or directly related to the combustion cycles. The measurement of these phenomena based on the crank angle offers the big advantage that cause and effect can be clearly correlated to each other.

AVL IndiCom™ and the Advanced indicating systems are perfectly suited for this, as they are able to provide signal acquisition as well as comprehensive evaluation.

The rotational vibration of the crankshaft can be analyzed without any additional costs, using the built-in delta-T function of the Advanced indicating systems to record the duration of the CA pulses. Using CalcGraf, measures such as instantaneous speed and rotational vibration can be derived and analyzed from these values.

Thus, resonance frequencies can be detected and analyzed and in idling conditions misfires as well as bad combustion can be identified for each cylinder even without pressure transducer. Additional comprehensive evaluations are possible by using the extended signal analysis which provides 3D representations and a complex FFT function as well as macros which enable the user to automatically evaluate a load or speed ramp.

Since it is possible to connect several angle encoders, vibrations can also be recorded and analyzed in relation to each other.

Figure 1: Vibration Analysis Using IndiCom Extended Signal Analysis

For the analysis of component stress and deformation, DMS sensors are attached to the engine components and the signals are recorded with high resolution on crank angle base. For the vibration analysis of the component, acceleration sensors are installed and the signals are also recorded on the basis of the crank angles. The high resolution of 0.025 KW also enables the analysis of high frequencies which are crucial for the acoustics of an engine; the integration of MATLAB™ runtime calculations enables the use of the same algorithms that are used for airborne sound measurement.

Synchronous Time- and Crank Angle-Based Measurement

For the optimization of dynamic and high dynamic processes of engine and power train, it is often not sufficient to record measurement values with the acquisition rate of 10 Hz to 100 Hz at the test bed.

AVL indicating systems are perfectly suited for fast / medium speed data acquisition. Especially the combination of fast time-based signals (such as for example gas pedal position, CAN bus signals, fast exhaust gas measurement etc.) with the measurement of combustion signals, provides a clear insight on how driver commands, reaction of the control systems and the resulting combustion processes are interconnected.

A broad range of time-based signals acquisition is available in AVL indicating systems:

These possibilities provide ideal solutions for measurements at the test bed as well as in the vehicle. By using the same acquisition systems data formats and evaluations, the highest possible degree of comparability is guaranteed. This greatly simplifies the parallel development and calibration of a drive train in the controlled conditions of a test bed and the real conditions in the vehicle.

The strength of IndiCom and CONCERTO™ lies in its ability of evaluating the different data by using automatic synchronization and transformation, to directly see the correlation between slower signals in the drive train, and the fast signals of the combustion analysis. The unique options for graphical evaluation, for example allow the combined display of cyclical combustion characteristics and time-based control signals, clearly making the correlation visible.

Figure 2: Concurrent Analysis of Time and Crank Angle Data

Thus, IndiCom™ provides a powerful basis for the analysis of dynamic powertrain behaviour whose optimization is growing more and more important, especially with regard to strict emission regulations and increasing driveability demands.

Your questions, comments, wishes?