Experiment investigation of injection parameters effects on injection stability of a high pressure common rail system

Abstract

High pressure common rail system can precisely control the injection time and injection pressure to improve the thermal efficiency of the engine. The injection characteristics of the system can affect the combustion and emission process of the engine. Injection stability is defined as variation characteristics of injection. This could have an unignored influence on combustion and engine output, while few study has been published. The primary objective is to establish evaluation systems and methods for injection stability. Then to study injection stability of the high pressure common rail system. Firstly, several parameters that have an important influence on the emission and combustion are identified. Based on the characteristics data obtained, it is verified that the stability parameters are in accordance with the normal distribution. Then, the five characteristic stability parameters of close speed of injection, cycle injection mass, injection delay, maximum injection rate and open speed of injection were quantitatively analyzed by using range, relative range, kurtosis and variance. It is found that the close speed of injection is greatly depend on injection pressure, the range of close speed varies from 1.8 to 5.1 mg/ms when rail pressure varies from 60 MPa to 160 MPa at 0.6 ms energizing time. The stability of injection mass depends on energizing time, the relative range in short energizing time can be four times than long energizing time. The maximum injection rate has similar characteristics with injection mass, it is also depends on energizing time. The range of maximum injection rate is reduced from the average of 0.6–0.7 mg/ms to 0.3 or even 0.2 mg/ms with the increase of energizing time. The injection delay and open speed of injection seems to be greatly affected by pressure fluctuation, since the observed data present complex rules. Pressure fluctuation in common rail can affect injection stability a lot.

Study of the Optimization of Rail Pressure Characteristics in the High-Pressure Common Rail Injection System for Diesel Engines Based on the Response Surface Methodology

“…In contrast to the traditional diesel engine fuel injection system, high-pressure common rail injection systems are widely used in various diesel engines because of their capacity for the flexible adjustment of injection pressure, independent and flexible control of injection timing and quantity, and high control accuracy, and they can effectively improve the economic aspects, power, and emissions of diesel engines [6][7][8][9][10]. In high-pressure common rail systems for diesel engines, the common rail pipe [11,12], as an important energy storage element in the common rail system, has an important impact on the control of the rail pressure fluctuations, common rail pressure and fuel injection quantity.…”

Study of the influence laws of the flow and cavitation characteristics in an injector control valve

“…For a long time in the future, they will still be an important source of power for construction machinery, ships, military equipment, and other fields 1 . As the “brain” and “heart” of a high‐speed and high‐power diesel engine, the high‐pressure common rail injection system enables a precise adjustment of the fuel injection to increase the output power of a diesel engine, improve fuel economy, and reduce the emission of nitrogen oxides and particulate matter significantly 2–4 . As the core component of a high‐pressure common rail injection system, a fuel injector represents the highest technology level and development difficulty for the common rail system, and it exerts an important impact on the power performance, fuel economy, and emission control of diesel engines 5,6 .…”

“…1 As the "brain" and "heart" of a high-speed and high-power diesel engine, the high-pressure common rail injection system enables a precise adjustment of the fuel injection to increase the output power of a diesel engine, improve fuel economy, and reduce the emission of nitrogen oxides and particulate matter significantly. [2][3][4] As the core component of a high-pressure common rail injection system, a fuel injector represents the highest technology level and development difficulty for the common rail system, and it exerts an important impact on the power performance, fuel economy, and emission control of diesel engines. 5,6 The strong flow recirculation and local depression inside a fuel injector provide favorable conditions for the occurrence of cavitation.…”

Effect of injection system parameters on overall performance of a small diesel engine

“…Park et al 27 observed IP and IT's effect with split injection technology on all measurable characteristics of a CRDI single-cylinder diesel engine. Gao et al 28 observed the impact on the injection stability parameters of the CRDI system like injection speed, mass of injection, delay, and injection rate.…”