Electric control oil atomizer

Abstract

The present invention discloses an electric control oil atomizer which includes a high speed electric control valve, an oil atomizer body and an oil injection nozzle. The high speed electric control valve is mounted on the top of the oil atomizer body; the oil injection nozzle is fixed at the lower end of the oil atomizer body. The lower end of the oil injection nozzle is a back taper type circular cone body which is corresponding to a back taper type circular cone cavity to form a variable nozzle. When injecting oil, the nozzle will change with the requirement of indication; the fuel oil will not be limited by the cutoff of injection hole. The control for the oil injection rate is realized. The electric control oil atomizer can be broadly applied to electric control common rail fuel systems of various internal combustion machines.

Description

Technical field [0001] The invention relates to an internal combustion engine oil supply technology, in particular to an electronically controlled fuel injector for an internal combustion engine. Background technique [0002] Due to the world's energy shortage and increasingly stringent emission regulations, the development of internal combustion engines is getting faster and faster, especially the electronically controlled fuel injection technology. Now the electronically controlled common rail fuel system is the fastest growing. Typical representatives are: Bosch, Germany The company's UNIJET, CRS electric control common rail system, Japan's Denso Corporation's ECD-U2, ECD-U2 (P) electric control common rail system, and other LDCR electro-hydraulic injection systems produced by DETPHI in the United States and LUCASVARITY in the United Kingdom Fuel injector, the piezoelectric crystal electronically controlled common rail system of German FEV company and Siemens has also bee...

AI Technical Summary

Problems solved by technology

At present, the fuel injectors (nozzles) used in various electronically controlled fuel systems are all inward-opening fuel injectors. The biggest disadvantage of the inward-opening fuel injectors is that the liquid flow area of ​​the fuel injection hole cannot be adjusted.

[0003] Because the fuel injection hole is the final outlet of fuel, the uncontrollability of the fuel injection hole limits the fuel injection characteristics and spray characteristics, making the fuel injector unable to achieve the ideal fuel injection effect under various engine operating conditions. From the formula m = pihj . L d . t It can be seen from the figure that when the unit time t and the single injection quantity L are constant, the fuel injection atomization mass m is equal to the ratio m of the fuel injection pressure pinj to the cross-sectional area d of the fuel injection hole, and this ratio m is proportional to pinj, It is inversely proportional to d. When pinj is constant, if the set value of d is large (heavy load condition), under light load condition, especially idle condition, since L is small, m will be small, causing engine idle speed instability or excessive idle speed. High, which is an important reason for the high idle emission of the engine. It also makes the engine idle fuel consumption too high. When the set value of d is small (under medium and small loads), the fuel supply per unit time is insufficient when the engine is working under heavy load conditions. The fuel injection duration can only be extended to meet the fuel injection volume requirements of the engine under heavy load conditions, which is equivalent to prolonging the time of diffusion combustion, deteriorating the thermal efficiency of the engine, reducing power, increasing fuel consumption, and increasing soot particles in the exhaust , after the pinj is increased, the duration of the same fuel injection is shortened, but at high speed and heavy load, the penetration distance of the oil beam increases, the amount of oil mist hitting the wall increases, and the atomization is not good, and there are still problems in the existing technology to increase the pinj a series of technical problems

[0004] Another disadvantage of the inner-opening injector is: the throttling effect between the needle valve sealing cone surface and the seat surface makes the fuel pressure in the pressure chamber and the real injection pressure lower and the injection hole is fixed, resulting in the engine running in small and medium The throttling effect is more obvious at load, especially at idle speed, the fuel atomization mass m is small, and the atomization is poor

[0005] The third disadvantage of the inner open injector is: the existence of the pressure chamber volume

[0007] When the oil outlet hole is equal to the oil inlet hole, the needle valve lifting pattern is a sinusoidal waveform with equal sides, that is, the fuel injection rate graph is also in a sine wave shape. The hole must be smaller than the oil inlet hole, and the oil inlet hole must be large enough relative to the diameter of the control piston to ensure oil cut-off, but the oil outlet hole must also be large enough relative to the diameter of the control piston, if it is too small, the needle valve will rise If the speed is too slow, the response characteristics of the injector will be affected. The diameter of the oil outlet hole is limited by the maximum pressure that the solenoid valve can withstand. If the diameter of the oil outlet hole is too large, the negative cut-off pressure of the solenoid valve will be large, and the electromagnetic coil will heat up. even burn out

[0008] The technical difficulty of the above-mentioned electronically controlled fuel injection system represented by Denso ECD-U2 is the determination of the parameters between the diameter of the oil outlet hole, the diameter of the oil inlet hole and the diameter of the control piston. This problem (the diameter of the oil inlet and outlet holes should reach a liquid flow difference of ±1% as much as possible), limits the response characteristics of the electronically controlled fuel injection system represented by ECD-U2, that is, the diameter of the oil outlet hole, the diameter of the oil inlet hole and the The design flexibility of controlling the diameter of the piston is relatively narrow, but the determination also determines the inclination of the shape of the fuel injection rate. When the fuel injection pressure is constant, the fuel injection quantity can only be controlled by the width of the command pulse (duty cycle)

[0009] In general, the existing electronically controlled fuel injectors have not yet achieved real fuel injection rate control, so that the electronically controlled fuel injectors cannot adapt well to the needs of the engine, especially when the load changes greatly (that is, the fuel supply changes Large) high-speed high-power internal combustion engine fuel injection needs

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