Understanding the Acoustic Oscillations Observed in the Injection Rate of a Common-Rail DI Diesel Injector

Author(s):  
Julien Manin ◽  
Alan Kastengren ◽  
Raul Payri

Measuring the rate of injection of a common-rail injector is one of the first steps for diesel engine development. At the same time, this information is of prime interest for engine research and modeling as it drives spray development and mixing. On the other hand, the widely used long-tube method provides results that are neither straightforward, nor fully understood. This study performed on a 0.09 mm axially drilled single-hole nozzle is part of the Engine Combustion Network (ECN) and aims at analyzing these features from an acoustic point of view to separate their impact on the real injection process and on the results recorded by the experimental devices. Several tests have been carried out for this study including rate of injection and momentum, X-ray phase-contrast of the injector and needle motion or injector displacement. The acoustic analysis revealed that these fluctuations found their origin in the sac of the injector and that they were the results of an interaction between the fluid in the chamber (generally gases) and the liquid fuel to be injected. It has been observed that the relatively high oscillations recorded by the long-tube method were mainly caused by a displacement of the injector itself while injecting. In addition, the results showed that these acoustic features also appear on the momentum flux of the spray which means that the real rate of injection should present such behavior.

Author(s):  
Julien Manin ◽  
Alan Kastengren ◽  
Raul Payri

Measuring the rate of injection of a common-rail injector is one of the first steps for diesel engine development. The injected quantity as a function of time is of prime interest for engine research and modeling activities, as it drives spray development and mixing, which, in current diesel engines, control combustion. On the other hand, the widely used long-tube method provides results that are neither straightforward nor fully understood. This study, performed on a 0.09-mm axially drilled single-hole nozzle, is part of the Engine Combustion Network (ECN) and aims at analyzing the acoustic oscillations observed in the rate of injection signal and measuring their impact on the real injection process and on the results recorded by the experimental devices. Several tests have been carried out for this study, including rate of injection and momentum, X-ray phase-contrast of the injector, and needle motion or injector displacement. The acoustic analysis revealed that these fluctuations found their origin in the sac of the injector and that they were the results of an interaction between the fluid in the chamber (generally gases) or in the nozzle sac and the liquid fuel to be injected. It has been observed that the relatively high oscillations recorded by the long-tube method were mainly caused by a displacement of the injector itself while injecting. In addition, the results showed that these acoustic features are also present in the spray, which means that the oscillations make it out of the injector, and that this temporal variation must be reflected in the actual rate of injection.


Author(s):  
Paolo Carlucci ◽  
Antonio Ficarella ◽  
Antonio Giuffrida ◽  
Rosario Lanzafame

The present work deals with the first researches into the real capabilities of an electronically controlled injector for common rail systems in realizing a proper shaping of the fuel rate with particular reference to its rising profile. Injectors equipped with standard and geometrically modified control valves have been investigated in detail by means of computer modeling and simulation. Experiments have been carried out in order to validate the feasibility of such a shaping and the injection rate meter based on the method proposed by Bosch was used. The main result of this work is a noteworthy dependence of the fuel rate on geometrical modifications in the piloting stage of the injector, since a certain difference in the slope of the first part of the fuel rate has been attained. The injector model has been finally used to investigate further geometrical modifications to be realized in order to achieve the desired fuel rate shaping.


Author(s):  
A.Y. Dunin ◽  
M.G. Shatrov ◽  
L.N. Golubkov ◽  
A.L. Yakovenko

For effective reduction of noise level and nitrogen oxide content in exhaust fumes of diesel engines, multistage fuel injection is used in combination with control of the front edge shape of the main injection. At the Moscow Automobile and Road Construction State Technical University (MADI), a method of control of the injection rate shape using an electric impulse was proposed, which was applied to the electromagnet of the control valve of the injector of the common rail fuel system. A computational and experimental analysis of the possibility of boot-type injection rate shape was carried out. The studies involved three most used designs of the common rail injector (CRI): CRI 1 featuring a control valve with shut-off cone and piston; CRI 2 consisting of a flat-lock control valve and a needle, which does not overlap the drain when the needle is in the highest position; CRI 3 with an injector that partially overlaps the drain. It was established that friction in the control valve piston and the guide surface pair of CRI 1 complicated the implementation of the boot-type injection rate due to its smoothing. CRI 2 and CRI 3 provide boot-type injection rate at different pressures in the fuel accumulator. The CRI 3 example shows that the instability of fuel supply during boot-type injection rate is comparable with that of fuel pre-injection, which is widely used in the organization of the common rail diesel engines working process.


Author(s):  
Mikhail G. Shatrov ◽  
Andrey U. Dunin ◽  
Pavel V. Dushkin ◽  
Andrey L. Yakovenko ◽  
Leonid N. Golubkov ◽  
...  

Fuel injection causes considerable oscillations of fuel pressure at the injector inlet. One of the reasons is hydraulic impact when the needle valve closes. For multiple injections, the previous injections affect the following. As both the fuel pressure in rail pac and the injection rate grow, the oscillations increase. The pressure oscillation range at the common rail injector inlet at pac=1500 bar is up to 350 bar, and at the rail pressure pac=500 bar, the amplitude decreases to 80 bar. Physical properties of the fuel are also important. As the viscosity of the fuel increases, its hydraulic friction grows which results in a rapid damping of pressure oscillations. The data for an injector operating on sunflower oil is presented. As compared with diesel fuel, the oscillations range decreases from 400 to 250 bar at the same operating mode. The influence of the interval between the impulses of a double injection on the injection rate of the second fuel portion was investigated. Superposition of two waves during multiple injections may result in amplification and damping of the oscillations. Simulation was performed to estimate the influence of fuel type and time interval Δτ between control impulses of a double injection on the injection quantity of the second portion at pressures of 2000-3000 bar. When the rail pressure pac grows, the oscillations and their impact on the injection process increase. For diesel fuel at pressure of pac=2000 bar, the variation in injection rates of the second portion is 2.36-4.62 mg, and at pac=3000 bar – 1.58-6.63 mg.


2016 ◽  
pp. 304-304
Author(s):  
Mikhail Shatrov ◽  
Leonid Golubkov ◽  
Andrey Dunin ◽  
Pavel Dushkin ◽  
Andrey Yakovenko

2019 ◽  
Vol 1 (04) ◽  
pp. 64-74
Author(s):  
Denur Denur

System bahan bakar dikelompokan menjadi dua bagian. Bahagian tekanan tinggi dan bahagian tekan rendah. Tekanan tinggi diawali dari komponen supply pump, common rail, injector. Tekanan rendah diawali dari tangki bahan bakar, supply pump dan pipa kelebihan baban bakar. Ada dua buah filter yang digunakan,yaitu filter utama, filter water separator yang difungsikan pada system bahan bakar, untuk mengatasi kebocoran bahan bakar dan berbagai permasalahan yang ada maka sebuah flow damper dan limiter valve di pasang pada bahagian common rail, juga sebuah overflow valve di pasang pada bahagian supply pump.  Common rail system yang menggunakan sebuah type accumulator chamber yang disebut common rail yang berfungsi untuk menyimpan tekanan bahan bakar yang tinggi, dan injectors yang terdapat electronically controlled solenoid valves akan menyemprotkan tekanan bahan bakar yang tinggi  kedalam ruang bakar, Injection system (injection pressure, injection rate, dan injection timing) dikontrol oleh ECM, dan selanjutnya common rail system dapat mengontrol injection system secara tersendiri, bebas dari pengaruh kecepatan putaran mesin dan beban mesin. Pada kerja mesin yang mengalami kegagalan kerja maka akan terjadi penurunan tekanan, penurunan volume injeksi yang berakibat kurang tenaga mesin. Penanganan dari kerusakan yang ada dapat dilakukan perawatan secara pengambilan data secara menggunakan alat dan percobaan yang dilakukan.


2018 ◽  
Vol 141 (2) ◽  
Author(s):  
Ling Wang ◽  
Guo-Xiu Li ◽  
Chun-Long Xu ◽  
Xing Xi ◽  
Xiao-Jun Wu ◽  
...  

According the actual structure and working principle of a fuel injector to build a model of the common-rail injector, including the control valve, the solenoid valve, and the needle valve of the injector. The model includes the leakage model for the control piston and needle valve that takes into account increasing leakage at high pressure. The performance of the fuel injector is investigated using a one-dimensional numerical model. Analyzing the effect of the system and structure parameters including common-rail pressure, injection pulse width, inlet and outlet hole diameter, and the injection nozzle on the injection characteristics of the fuel injector. Results show that the geometric parameter is the main property affecting the flow characteristic of the injector, which includes the flow rate of inlet and outlet hole, pressure waves in the control chamber and injection rate. The common-rail pressure, injection pulse width and the geometric parameters mainly affect the injection performance, such as the injection rate and injected volume. The investigation result can provide some useful information to improve the injection characteristic in follow-up studies.


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