Mechanical distortion and performance associated with cylindrical components in diesel injector systems.
As European and US vehicle emissions regulations tighten, more effective
methods of reducing diesel engines pollutants must be devised. Increasing the injection
pressure results in smaller fuel droplets and consequently more efficient combustion with
a reduction in emissions output. However, to gain acceptable levels of NO. and
particulates, required pressures must be of the order of 1800 to 2400 bar. At this level the
components within the diesel injector and pump experience an appreciable level of
distortion, that can, in severe cases, lead to leakage and a loss in pumping efficiency. It is
therefore critical that an accurate means of determining the distortion and associated
leakage is established.
An efficient analytical method of solution for the problem of mechanical
distortion of a diesel pump is presented. Both the EUI (Electronic Unit Injector) and CR
(Common Rail) injection systems use essentially in-line pumps for which this technique
allows the individual components (principally the plunger and barrel) to be analysed.
Also, combined fluid-elastic systems are considered in both CR and EUI cases. An elastic
integral equation formulation is optimised for a cylindrical geometry and this is used to
evaluate key features of the system such as pressure distributions and variations in film
thickness during the pumping stroke. It is then straightforward to evaluate other
parameters such as leakage and both magnitude and direction of fluid flow within the
Simplification of elastic models is not required and as such this thesis also
considers the effect of ports on the fluid flow and pressure distribution and also the
relative orientation and axial position of the plunger within the barrel. This allows a
detailed description and explanation to be made of the behaviour of the diesel pump. A
key advantage of the method is that the fluid and elastic solvers may be decoupled and
developed separately. This provides a means of extending the scope of the method
beyond that presented here.