Measurements of Time-Resolved Mass Injection Rates for a Multi-Hole and an Outward Opening Piezo GDI Injector
Paper i proceeding, 2015

Time-resolved mass injection rates of an outward opening piezoactuated and a solenoid actuated multi-hole GDI injector were measured to investigate (1) the influence of both hardware and software settings and (2) the influence on the injection rates from a wide range of operational parameters and (3) discuss limitations and issues with this measurement technique. The varied operating parameters were fuel pressure, back-pressure, electrical pulse width, single/double injection and injection frequency. The varied hardware/software parameters were injector protrusion, upstream fuel pressure condition and the cut-off frequency of the software's low-pass filter. Signal quality was found to be dependent on both hardware and software settings, especially the cut-off frequency of the low-pass filter. Measurements with high signal quality were not possible for back-pressures lower than 0.5 MPa. For the smallest possible injections, the piezo-actuated injector was found to be superior since it can inject very small amounts of fuel very accurately with little fuel pressure dependency. For engine realistic back-pressures, the multi-hole injector was found to be back-pressure independent. The piezo injector however was found to be strongly influenced by the back-pressure. The dynamic range was found to be much higher for the piezo injector, and the non-linear flow area was much larger for the multi-hole injector. Both injectors were capable of double injections but the piezo can use shorter dwell times. Effects of upstream fuel pressure fluctuations, especially on the second injection of a double injection, must be carefully taken into account.

Direct Injection

Zeuch method



injection rates


lean burn



Petter Dahlander

Chalmers, Tillämpad mekanik, Förbränning

Daniele Iemmolo

Politecnico di Torino

Yifei Tong

Politecnico di Torino

SAE Technical Papers: SAE 2015 World Congress and Exhibition; Cobo CenterDetroit; United States; 21 April 2015 through 23 April 2015




Strömningsmekanik och akustik