INVESTIGATIONS ON THE VALVE TRAIN / MEASUREMENTS OF THE VALVE TRAIN DYNAMICS
The analysis of the valve train is carried out on the basis of the measured, analog variables valve lift or valve speed in relation to the camshaft position. Due to the increasing complexity of valve actuation, it is a crucial element in the optimization of thermodynamics and thus in the development of economical and powerful internal combustion engines. In particular, the dynamic opening and closing behavior of the valve (e.g. touchdown speed) as a function of the engine speed is the focus here. By means of the ROTEC software module Valve Train Analysis, these parameters can be evaluated automatically.
MEASUREMENTS ON THE MOTORED CYLINDER HEAD
In order to be able to reliably assess the opening and closing behavior, the measurements and calculations of the three measured variables valve lift, speed and acceleration are necessary. You can use two different measurement methods for this: measurement on motored cylinder head using a laser vibrometer and in fired operation using magnetoresistive sensors. The valve lift can be measured both on motored cylinder head and in fired operation using magnetoresistive sensors. For this purpose, the speed signals and angular positions at the camshaft drive system are recorded. In the first step, the torsional vibration behavior of the camshafts can be derived from this. Afterwards, you can fed the measurement data from speeds and valve lift to a special software tool for valve trains. This allows variables such as valve speed, acceleration, opening and closing behavior, lift loss, resonance and stress behavior to be automatically evaluated and graphically displayed.
VALVE TRAIN INVESTIGATIONS ON FIRED ENGINE
Measurements on fired engines have advantages over those on motored cylinder heads. For example, you can study the effects of gas forces under real torsional vibration and thermal expansion behavior of the camshafts or cylinder head can on the fired engine. These effects are becoming more and more important with increasing charging and exhaust gas backpressures (particulate filters).
Another advantage is that the cost of setting up a sometimes very complex test part carrier can be saved, although the fired operation of a test engine and the application of the relatively complex MR measurement technology is certainly also a cost-intensive matter.
SOFTWARE MODULE FOR AUTOMATED EVALUATION OF DYNAMIC PARAMETERS
The manual evaluation of dynamic parameters, such as the valve touchdown speed or the time of dynamic opening and closing, is very laborious with a large number of different operating points and takes up a lot of your working time.
The “Valve train” software module was developed with the aim of automating these evaluations. This not only reduces the evaluation time, but also the size of the test matrix and, accordingly, the utilization time of the test bench. Instead of measurements at constant, discrete speeds, you can now run speed ramps.
The software module can be used to evaluate the following parameters, among others: Angular position of dynamic opening and closing, touchdown speed, stroke loss, lift-off, valve bounce, mechanical load on components (surface pressure during cup drive), stroke area, valve overlap, etc.).
The software evaluates curves of several signals (stroke, velocity and acceleration) and presents them automatically for each cycle in a comparable way with the corresponding result parameters. For some analyses, additional evaluation methods have been predefined for the specialized user (e.g. touchdown speed).
In addition to the multitude of analysis options, cycles with signal errors can be automatically recorded and removed from the evaluations.
The application of the measurement technology as well as on-site measurements, analysis and evaluation can be completely provided and carried out by ROTEC ENGINEERING.
In order to record the interactions between valve actuation and timing, or to explicitly analyze the functional behavior of the camshaft phasing unit, ROTEC ENGINEERING carries out tests on both electric and hydraulic camshaft phasing units.
MEASUREMENTS ON MOTORED CYLINDER HEAD
- Valve lift and valve speed measurement with laser vibrometer
- Camshaft position measurement with rotary encoder
- Classic measurement method with high-precision measurement signals
MEASUREMENTS ON FIRED ENGINE
- Valve stroke measurement with prepared valve stem and MR sensor technology
- Deviation from laser vibrometer < 20 µm
- Special software solution for calculation of stroke signals from sensor signals (SIN, COS)