Measuring Valve Train Dynamics Using The HSV-2002 High Speed Laser Vibrometer

The optimization of the dynamics of mechanically or electromagnetically controlled valve gears is an important factor in optimizing engine performance. Because of their direct influence on motor dynamics, power, pollutant emission, durability and noise level, any small deviation from the predicted valve response can affect the engine performance adversely. The numerical modeling of valve gears is complex and requires very accurate experimental measurements for verification of the calculated values.

At the request of several leading automobile and engine manufacturers who needed high velocity capability for their motor sports divisions, Polytec developed the HSV-2002 high-speed differential vibrometer system. The HSV-2002 system is ideally suited for the task of fast and accurate measurement of the most important parameters, such as valve lift and speed.

When compared to Polytec's differential fiber vibrometers, the HSV-2002 measures to higher velocities (± 30 m/s at 50 kHz bandwidth), features easier setup and operation, is more rugged and has much better optical sensitivity. For these reasons the HSV-2002 is also popular for valve train dynamics testing on lower speed engines (<10 m/s) built for consumers.

The HSV system was designed for optimal signal quality, even under the toughest environmental conditions. For this reason, Polytec chose a configuration with two independent interferometer systems and separate RF signal conditioning for the measurement and reference channel. This configuration maximizes optical sensitivity and significantly reduces signal drop-outs, resulting in excellent data quality.