Crank Vibration
Our
Crank Synchronous Acquisition (CSA) device not only provides cylinder
pressure analysis but can also be used for complex vibration monitoring,
without the need for cylinder pressure sensors.
With
just the normal crankshaft and camshaft sensors it is possible to
analyse crankshaft torsional vibration with respect to the natural
resonances of a compression/expansion combustion engine.
These
vibrations, and their minimisation, are the key reason many OE vehicles
are fitted with Torsional Vibration Dampers (TVD), or harmonic
balancers as standard.
The CSA tool
measures every tooth interval in the 720 degree four-stroke cycle and
derives crankshaft acceleration and deceleration from this data, with
respect to the average engine speed.
Along
with a real time display of these resonances, Fourier Analysis of the
signal provides the orders of vibration (or multiples of the basic
engine cyclical resonance) in real time.
From
this data it is possible to analyse and improve torsional dampers for a
given engine installation. A complete dyno pull can reveal the orders
of torsional vibration at all engine speeds and their magnitude.
Crank Twist
If
a second 60 tooth sensor wheel is installed at the other end of the
crankshaft the CSA device can measure crankshaft angular twist as well
as vibration. Normal tools cannot derive this data as the twist varies
continuously as the engine rotates. The CSA device can do so because all
tooth intervals are passed to the PC application and logged for later
analysis.