A vast majority of the medium and high speed diesel engines are equipped with multihole injection nozzles nowadays. Inaccuracies in
workmanship and changing hydraulic conditions in the nozzles result in differences in injection rates between individual injection nozzle
holes. The new deformational measuring method described in the paper allows injection rate measurement in each injection nozzle hole.
The differences in injection rates lead to uneven thermal loads of diesel engine combustion chambers.
The criterion of the injected fuel is expressed by the deformation of membrane occurring due to the rapid rise of the fuel in the measuring
space and the collision of the pressure wave against the membrane. The pressure wave is generated by the injection of the fuel into the
measuring space. The pressure wave is analysed by the theory of hydraulic impact in the high-pressure pipes. The membrane deformation is
measured using strain gauges, glued to the membrane and forming the Wheatstone bridge.We devoted special attention to the temperature
compensation of the Wheatstone bridge and the membrane, heated up during the measurements. All four strain gauges were arranged in a
full Wheatstone bridge configuration and glued to the membrane. The strain gauges are all exposed to identical temperature resulting in a
temperature compensated Wheatstone bridge.
Described in the paper are the measurements of a three-hole nozzle and the reasons analysed of injection rate differences in the injection
nozzle holes. We divided the causes of the inequality in the injection rate into structural and hydraulic groups