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U. Schmid, D. Schmitt-Landsiedel, G. Krötz:
"Evaluation of Electron Beam Welding Technique for the Integration of Robust Sensor Elements into High-Pressure Automotive Systems";
Microsystem Technologies - Micro- and Nanosystems - Information Storage and Processing Systems, Vol. 14 (2008), 8; 1193 - 1203.

For ``on board´´ diagnosis purposes of the
injected fuel quantity flow sensitive elements based on the
thermo-resistive measurement principle were integrated
into finished Common Rail injection nozzles of valvecovered
orifice (VCO) or mini-sac hole (MSH) class.
Electron-discharge machining as well as electron beam
welding technique are key technologies for a reliable integration
procedure. To demonstrate negligible influence on
the hydraulic performance of the nozzle after modification
an optical measurement set-up is used to record temporally
resolved the propagation of the spray patterns ejected from
the six injection holes simultaneously. From these investigations
the impact on the structural distortion of the valve
caused by the welding seam is proved as its position can be
directly linked to any chances in spray performance of each
individual injection hole. Reducing the energy input during
the electron beam welding lowers substantially the asymmetry
in spray patterns from hole to hole as the needle
uncovers the six injection holes more symmetrically.
Besides this important finding, the numerical calculations
indicate that the implementation of the sensor chip slightly
amplifies the asymmetry induced by the welding process
due to an additional weakening of the nozzle body which
is confirmed experimentally. Despite these challenges,
however, it is demonstrated that appropriate parameters for
the integration procedure can be found affecting the
hydraulic performance negligible compared to the original
state.

http://dx.doi.org/10.1007/s00542-008-0645-9