Naslov
Brtvljenje konusnog rastavljivog spoja visokotlačne cijevi i pumpe za izravno ubrizgavanje benzina
(Sealing of conical separable joint between high pressure pipe and gasoline direct injection fuel pump)

Autori
Malacko, Matija

Vrsta, podvrsta i kategorija rada
Ocjenski radovi, diplomski rad, diplomski

Fakultet
Fakultet strojarstva i brodogradnje

Mjesto
Zagreb

Datum
28.03

Godina
2014

Stranica
98

Mentor
Vučković, Krešimir

Ključne riječi
high pressure screw joint ; leakage tightness ; high pressure pump ; gasoline direct injection

Sažetak
The tightness of fuel-flow components is an important aspect in the development of gasoline engines. In addition to the safety-related fuel leakage there is also the reduction of evaporative emissions (SULEV) in the focus of development activities. Critical in this regard is the screw joint of the high pressure pipe connecting the common rail to the high pressure pump for engines with gasoline direct injection. Named screw joint consists of: fitting, high pressure pipe ending (pipe head) and union nut which holds all components together. Task was to investigate influence of changing two different materials for same type of geometry of fitting, as well as influence of two types of pipe head. One head is produced by cold forging in a die, thus having higher strength than prior to the forging, and second one is produced by fine turning, and then it is hard soldered to the pipe. That means, that turned head pipe has lower strength than prior to the soldering, because material went through recrystallization. With investigation, main influencing factors that influence leakage tightness of the screw joint were determined: axial force, sealing seat geometry, surface quality and material properties of the sealing partners. To properly conduct leakage measurements, Design of Experiments method was used to make test plan which will give how parts need to be sorted so that one varies main influencing parameters, to later get correlation for which combination of them leakage tightness of the joint changes. Main influencing parameters to vary for leakage measurements are: fitting material, pipe head, fitting Rpk, pipe Rpk, cone angle and axial force values. Measurement of the residual clamping force was conducted. Method used was loosening torque, loosening angle with estimation of elastic origin previously done on model joints. Aim was to calculate maximum axial force applied through indent width measurement, i. e. width of plastic deformation of the contact zone. Generally, forged head pipes were mostly leak tight, while turned ones were quite the opposite. Regression of data provided that helium as test medium is better than n-heptane because of higher adjusted R2 value (goodness of fit), better distribution of residuals, as well as correlation of influences and Pareto plot with the experiment results. Most influences on the leakage rate for helium had terms (in ascending order): type of pipe head, cone angle, pipe Rpk, pressure and axial force. Fitting material does not have any influence on leakage rate. Leakage rate can be quantified as a polynomial of parameter coefficients from the regression table.

Izvorni jezik
Engleski

POVEZANOST RADA