Aleš Prokop

Experimental Validation Of The Gearbox NVH Parameters

Abstract The noise, vibration and harshness (NVH) plays an important role in the transmission area of automotive industry. To understand all the impacts on the gearbox’s global dynamic behavior it is necessary to gain information from a simplified model, create methods and get an appropriate and well correlated results with the experiment. The method itself can be afterwards reused for more complex transmission, which could be supported by other measurements. This paper deals with creation of a gearbox’s simplified model, including essential mechanisms as gear mesh stiffness, backlash, bearing stiffness and modal properties of the main components. Except for the presented model, more models with different difficulty levels are used. Numerical results are compared with data from experiment with good correlation.

Gear Drive System Simulation of Input Parameters Effect on Rattle

The understanding of gear dynamics is essential to design the power transmission with low vibration and noise radiation level. The virtual prototype is proposed for transmission dynamic investigation. This article deals with investigation of input parameters effect on gear rattle. The rattle noise is caused by hitting the tooth by each other, which can be noticed by vibrations evaluation on the gearbox housing. The evaluation is done by surface normal velocity comparison, which is connected to the emitted noise. The simulation results show that the torque and backlash has influence on the tooth contact loosening at the starting of rotation.

Gear Drive System Simulation with Different Model of Input Speed

Presented paper deals with investigation of the basic gearbox parameter effect on the surface normal velocity of the gearbox top cover. First the single stage gearbox was designed and manufactured for the inputs and results validation. Afterwards a dynamic model was built and each part of it was validated by an appropriate technical experiment. The presented part of investigation focuses on comparison of different kind of input speed—ideal smooth increasing input speed and variable input speed. The evaluation is done by amplitude of gearbox surface normal velocity. The main goal is to describe dynamic behaviour of whole gearbox by numerical simulation and find the numerical model recognisability. The simulation results show that the variable input speed has strong influence on dynamic behaviour.

Simulation Approaches for the Solution of Cranktrain Vibrations

Shrnutí Vývoj moderních pohonných jednotek vyžaduje využívání pokročilých výpočtových metod, nutných k požadovanému zkrácení času tohoto vývoje společně s minimalizací nákladů na něj. Moderní výpočtové modely jsou stále složitější a umožnují řešit mnoho různých fyzikálních problémů. V případě dynamiky pohonných jednotek a životnosti jejich komponent lze využít několik různých přístupů. Prvním z nich je přístup zahrnující samostatné řešení každého subsystému pohonné jednotky. Druhý přístup využívá model pohonné jednotky obsahující všechny hlavní subsystémy, jako klikový mechanismus, ventilový rozvod, pohon rozvodů nebo vstřikovací čerpadlo, a řeší všechny tyto subsystémy současně i s jejich vzájemným ovlivněním. Cílem článku je pomocí vybraných výsledků prezentovat silné a slabé stránky obou přístupů. Výpočty a experimenty jsou prováděny na traktorovém vznětovém šestiválcovém motoru. Abstract The development of modern powertrains requires the use of advanced CAE tools enabling a reduction in engine development times and costs. Modern computational models are becoming ever more complicated and enable integration of many physical problems. Concentrating on powertrain dynamics and component fatigue, a few basic approaches can be used to arrive at a solution. The first approach incorporates a separate dynamics solution of the powertrain parts. The second one solves a complete powertrain model including all significant parts, such as cranktrain, valvetrain, gear timing drive and injection pump. The paper deals with dynamics and fatigue analyses solved using different approaches. Computed and measured results relate to a tractor compression-ignition in-line six-cylinder engine.