Research Of Processing Valve Train Dynamic Data And Parameter Identification Method

Valve train is an important component of internal combustion engine, whether reasonable or not of its design is directly affect the performance of the whole machine. So the valve train dynamic characteristics and fatigue reliability is currently one of the main directions of research of internal combustion engine. On the basis of the extensive study referring the domestic and foreign literature about valve train, and combining with the actual situation of the enterprise cooperation projects, this paper makes a in-depth study about valve train of a certain type of domestic diesel engine, using the research method of collecting experimental data, processing dynamic data, analysis the dynamic characteristic parameter and finite element model simulation analysis. The main research work can be summarized as follows;1. Introduce the Valve train dynamic test system sketch and the acquisition principle and method of acceleration signal, strain signal, angle signal, and the TDC signal data. Use the whole cycle sampling principle to sample the four kinds of signal, obtain a complete cycle dynamic test data through multi cycle average method, and get the valve velocity signals with using the valve acceleration signal integral method.2. Use the least square method and the multi cycle average method effectively to removes the trend component and drift in acceleration signal, Eliminate low frequency interference of the acceleration signal. In view that it is difficult to determine the frequency range of interfering signal, and can’t totally eliminate the distinguish signal on the condition of not affecting real signal at present, According that every cycle of dynamic data has different frequency response characteristics; this paper proposes a method using both FFT analysis and wavelet packet analysis together, it makes use of FFT analysis to determine the frequency range of the interfering signal, and takes advantage of the superiority of reconstructing signal of wavelet packet to process the valve train dynamical data, The research shows a good result.3. Make the analysis of valve train dynamic characteristic parameters at different valve clearance and rotational speed, analysis the valve velocity and tappet stress to study its aspects to fly off and valve bounce back of valve train.4. Dynamic damping affects effacingly the valve stability when the valve train is draping or running. Valve draping dynamic damping reflect the energy consume characteristic of the valve draping course. There are many factors affect the energy consume during the course. It is difficult to analysis the energy consume course with accurate theory. It is analysis the dynamic damping trend with the changing of other parameters in this paper, and calculated the variation of the dynamic damping according to other parameters with using the measuring dynamic data.5. Valve spring is the key component to the performance of the whole valve train. From the calculation, it is seen that when the speed is in a certain range, the data of the dynamic stiffness will fluctuate at the vicinity of the static stiffness. Therefore, Valve spring of the valve train stiffness is close to linearity, so the dynamic stiffness doesn’t fluctuate significantly, and its nonlinearity is small.6. Use finite element analysis software HYPERMESH, ABAQUS to simulate the valve seating process. There is a stress concentration obviously in the valve and valve seat contact parts, and increase along with the seating velocity increasing. But a circumferential stress distribute uniformly on valve seat. under the valve spring preload and seating impact force, the deformation at the site of contact accumulated more and more big, eventually leading to the valve seat fatigue failure.