Marine low-speed diesel engine common-rail fuel injection system with external pressurization piston

Abstract

A marine low-speed diesel engine common-rail fuel injection system with an external pressurization piston comprises a servo oil supply portion, a hydraulic pressurization portion, a common-rail fuel injector and a fuel supply portion. The servo oil supply portion supplies servo oil to the hydraulic pressurization portion, and the fuel supply portion supplies fuel to the hydraulic pressurization portion. In the hydraulic pressurization portion, an upper pressurization piston cavity and a lower pressurization piston cavity are formed between the pressurization piston and a pressurization piston body, and a pressurization piston control valve controls connection or disconnection of the servo oil supply portion and the upper pressurization piston cavity to achieve pressurization or absorption of fuel. In the common-rail fuel injector, one path of high-pressure fuel which is pressurized enters a control cavity, the other path of the high-pressure fuel which is pressurized enters a fuel containing tank, and a fuel injection control electromagnetic valve conducts whole working condition accurate flexible control on fuel injection timing and the circulating fuel injection quantity of the common-rail fuel injector. The axial height of the fuel injector is reduced, installation is facilitated, complete independence of a fuel pressurization process and a fuel injection process and multiple injections are achieved, fuel economy of a diesel engine is improved, and emission performance is improved.

Description

technical field [0001] The invention relates to an engine fuel injector, in particular to a common-rail fuel injection system with an external supercharging piston for a high-power marine low-speed diesel engine, and belongs to the technical field of diesel engines. Background technique [0002] Mechanical fuel injectors cannot achieve precise and flexible control of fuel injection timing, fuel injection regularity and cycle fuel injection volume, and due to the existence of pulsating fuel supply, the fuel injection pressure is low and the fuel atomization quality is poor under low-speed and small-load conditions. Poor, which reduces the fuel economy of diesel engines and deteriorates the emissions of diesel engines, so mechanical injectors can no longer meet the requirements of increasingly stringent emission regulations. [0003] The common rail fuel injection system for diesel engines can realize precise and flexible control of fuel injection timing and cycle fuel injecti...

AI Technical Summary

Problems solved by technology

The disadvantage is that this patent uses a flat valve with poor sealing performance under high pressure conditions to seal the oil orifice on the control chamber, especially when the fuel pressure in the control chamber is relatively high or super high pressure , the sealing performance of the flat valve deteriorates sharply, and the fuel leakage increases rapidly, which seriously affects the working characteristics of the common rail injector

[0006] Chinese patent CN 102392771A uses a two-position three-way solenoid valve to replace the two-position two-way electromagnetic control flat valve on the Chinese patent CN 102022241A that controls the movement of the booster piston, which solves the problem of poor high-pressure sealing caused by the use of flat valves

But its shortcoming is that this patent is the same as patents CN 102022241A and CN 102705121A. It realizes the control of the movement of the booster piston through the control of fuel drain and oil filling in the control chamber under the small head of the booster piston, thereby Complete the fuel pressurization process and the oil suction process, however, this control method for the movement of the booster piston requires precise matching of the oil inlet orifice and the oil discharge orifice on the control chamber, which will inevitably lead to increased processing costs and difficulty in manufacturing increase, and because the upper part of the booster piston always has high-pressure fuel, when the booster piston resets upward, due to the downward force generated by the high-pressure fuel, the booster piston is difficult to reset quickly, which will significantly reduce the effective filling time , which limits the coverage of diesel engine power

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