Injection nozzle for internal combustion engines

Details Injection nozzle for internal combustion engines Injection nozzle for internal combustion engines

1994-12-12

1996-01-09

Moulis, Thomas N.

Internal-combustion engines

Combustion chamber means having fuel injection only

Having a particular relationship between injection and...

239584, 2395332, 23953312, F02M 6108

Patent

active

054820189

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

The invention relates to a fuel injection nozzle for internal combustion engines, in particular those with direct injection, as generically defined hereinafter. In an injection nozzle of this type, known from European Patent Disclosure EP-A-209 244, the sealing seat, formed by the valve seat and the valve cone and having a circular linear form, is formed on the radially outer circumference of the valve seat or valve cone in that the cone angle of the valve seat on the nozzle body is smaller than the cone angle of the valve cone at the closing head of the valve needle. Moreover, the control edge at the transition from the valve seat to the guide portion of the nozzle body is rounded. This embodiment forms an annular gap of wedge-shaped cross section between the face of the valve seat and the valve cone and the circumference of the guide portion of the valve needle; in this annular gap, fuel collects aligned with the opening cross section of the injection ports of the valve needle when the valve is closed; especially at the injection onset, this collected fuel hinders stream preparation. Moreover, the fuel streams emerging from the injection ports sometimes strike the rounded portion and the faces tapering outward of the valve seat and valve cone, leading to an energy loss for fuel preparation.
A similar fuel injection nozzle is disclosed by U.S. Pat. No. 2,035,203; in it, the valve needle has a shaft with the closing head and sleeve surrounding the shaft that covers the longitudinal grooves in the shaft and that has slits in its face end oriented toward the valve that form injection ports of a defined cross section. In this known injection nozzle, although good stream preparation is attained, the tightness of its valve leaves something to be desired, because of the flat seat between the valve cone and the valve seat. This disadvantage is made even worse by the fact that the valve needle with the valve cone and the sleeve mounted is guided in the nozzle body, and so the tight seat fit is displaced by an offset of the axes of these components.


ADVANTAGES OF THE INVENTION

The injection nozzle according to the invention has an advantage that the injection streams are prepared with very low energy loss, and that because of the sharp control edge on the nozzle body, the instant that the nozzle cross section opens at the onset of the needle stroke is unequivocally defined. Moreover, because of the sealing seat diameter immediately radially adjoining the control edge, the diameter of the sealing seat is virtually identical to the hydraulically effective diameter of the piston slide of the valve needle in the nozzle body. As a result, it is possible to minimize the influence of counterpressure. Since the counterpressure on the side toward the combustion chamber acts upon the entire surface area resulting from the sealing seat diameter, but the hydraulic opening force acts only on the annular face between the upper needle guide and the diameter of the guide portion or of the piston slide of the valve needle, it is also advantageous, for satisfactory opening of the valve needle even at maximum combustion chamber pressure, that the hydraulically effective slide diameter is as great as possible, or in other words is as close as possible to the valve seat diameter.
Advantageous further features of and improvements to the fuel injection nozzle are possible with the provisions set forth herein. Embodying the valve needle of the injection nozzle so that the valve cone (17) is formed on an annular body (60) and secured to the closing head (16) of the valve needle (15) makes for a valve in which it is structurally simple to disposed the linear sealing seat in the immediate vicinity of the control edge of the valve body.
Exemplary embodiments of the invention are shown in the drawing and described in further detail below. FIG. 1 is a longitudinal section of a fuel injection nozzle; FIGS. 2-5 show different exemplary embodiments of the end toward the combustion chamber of the injection nozzle of

REFERENCES:
patent: 3249308 (1966-05-01), Cadiou
patent: 3801021 (1974-04-01), Jakob
patent: 4181144 (1980-01-01), Landen
patent: 5127584 (1992-07-01), Sczomak
patent: 5282577 (1994-02-01), Neitz

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