Developing modern vehicles means developing a high-integrated mechatronic system with requirements from different domains. One aspect is the optimization of the NVH behaviour. NVH describes vibrations and noises which appear in the vehicle and which are often deranging and thus influencing negatively the comfort impression. In times where topics like energy efficiency and environment protection dominate, Noise Vibration Harshness (NVH) in the vehicle development becomes more and more a challenge. The NVH behaviour must always be considered in the context of parameters such as abrasion/durability, energy efficiency, costs, driving pleasure and the CO2 reduction. Adjustment and optimization of the mechatronic system 'vehicle' is therefore domain-spanning and requires appropriate development tools and methods. Frontloading and the integration of the different domains in early stages of the product development process are necessary. Nowadays it is possible to do NVH analysis in these early stages using the Finite Element Simulation or Multibody Simulation Tools. In order to realize NVH capable models and to validate those, real measurements are required. For a model creation as realistic as necessary there is the need for reactionless and reproducible measurement methods. Present reactionless measurements are realized well through laser technology. Especially in the automotive sector a good reproducibility is a great challenge. The reproducibility can be improved through the classical approach 'from road to rig'. Using test benches allows analysing specific phenomena without unmeant influences which exists e.g. in tests on the road. Through the great variety of the drivetrain concepts and driving modes in present vehicle concepts there is the possibility to adjust and vary an infinite number, for the most part, parameters which influence the comfort. This starts with simple parameters such as engine temperature or vehicle velocity. For measurements for example, at a specific velocity the engine temperature is situated in a specific temperature range. When acoustic measurements are in the foreground it is possible that the measurements on the test bench need to be carried out without ventilation or cooling. In order for the engine not to overheat while performing extensive measurements, the temperature needs to be monitored. If the temperature exceeds the limit the measurement is aborted automatically and a cooling phase is initiated. After cooling the driving point is to be started-up and the measurement is to be continued. The number of requirements for a good reproducibility rises with increasing complexity of the drivetrain concept. Especially in the field of hybrid drives, the coupling of the drive units combustion engine and electric engine involve a lot more parameters and operation modes than the sole combustion-engined or electric driving. In this case, the operating mode plays an important role. In a fully automated measurement process the measurement at low state of charge is aborted and recuperated through the combustion engine. After reaching a sufficient state of charge, the operating state is started-up and the measurement continues. In this paper a measurement process which offers the possibility to do automated data acquisition of operation mode depending NVH phenomena on a roller test bench is presented. Especially for NVH development in the context of energy efficiency and CO2 reduction it is a very important approach. Hybrid electric vehicle are very complex systems with a large number of different operation modes. Special test and validation methods are necessary and one is here. A further step for the automation is the resonance recognition. For this analysis the velocity resp. the engine speed where the analyzed component oscillates are chosen. For this purpose a ramp from idle-running until maximum speed is ran and the surface oscillations are measured at one point or more. On the basis of these selective measurements the resonance is to be recognized and the corresponding velocity deduced. These velocities are the basis for fully automated test programs. Using real driving cycles in a virtual city with virtual traffic can be used too instead of the ramp from idle-running to identify critical states in a customer relevant driving cycle. With the use of automated test cycles and a semi-automated NVH data acquisition a step forward to the automated acquisition of operating dependent NVH relevant phenomena is achieved. In order to measure a vehicle completely with a 3D PSV there is the necessity to reposition a few times the scan heads because only the visible area can be covered. All the single measurements are then assembled into an overall figure. If the repositioning of the scan heads is performed by an industrial robot this enables nearly full automation. A process named RoboVib developed by Polytec has already implemented this approach for an experimental modal analysis.
Automated acquisition of operation mode depending NVH phenomena on a roller test bench
Automatische Erfassung betriebszustabdsabhängiger schwingungskomfortrelevanter Phänomene am Rollprüfstand
2009
16 Seiten, 13 Bilder, 11 Quellen
Aufsatz (Konferenz)
Englisch
Rollprüfstand , Anwendung im Fahrzeugbau , Schwingungsverhalten , Komfort (Eigenschaft) , Fahrzeuggeräusch , Messdatenerfassung , Betriebszustand , Fahrzeugschwingung , mechatronisches System , Produktentwurf , Finite-Elemente-Methode , Mehrkörpersimulation , Pkw-Motor , Fahrgeschwindigkeit , Motortemperaturwarngerät , Energieeffizienz , CO2-Minderung , Hybridfahrzeug , automatisches Prüfsystem
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