Injection nozzle for internal combustion engines

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

1994-12-12

1996-06-04

Weldon, Kevin

Fluid sprinkling, spraying, and diffusing

Fluid pressure responsive discharge modifier* or flow...

Fuel injector or burner

23953312, F02M 6108

Patent

active

055225500

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

The invention is based on a fuel injection nozzle for internal combustion engines as generically defined hereinafter. In an injection nozzle of this type, known from German Offenlegungsschrift DE-OS 40 06 488, the valve needle has a plurality of axially parallel longitudinal grooves in the circumference of the piston embodied as a collar, which extend downstream from the face end of the piston that defines the pressure chamber to the valve cone of the piston. When the valve needle opens, the region of the longitudinal grooves near the valve cone is uncovered progressively as an injection cross section; the resultant flow vector is always defined by the shortest path from the inlet of the longitudinal groove to the injection cross section. Since the longitudinal grooves extend axially parallel as far as the injection cross section, a strongly axial directional component is imparted to the injection stream; orientation at a predetermined cone angle adapted to the engine combustion chamber is not possible.
A precise alignment of the injection streams at a predetermined cone angle is present in a fuel injection nozzle according to European Patent Disclosure EP-A-209 244, in which the injection direction is determined by injection ports that pierce the shaft of the hollow-drilled valve needle at an obtuse cone angle near the valve cone. Flaring open or breathing of the hollow valve needle at high pressures can cause problems with respect to reliable function in this embodiment of the valve needle. Moreover, the axial bore in the shaft of the valve needle is a hindrance to miniaturizing the injection nozzle.


ADVANTAGES OF THE INVENTION

The fuel injection nozzle according to the invention has an advantage that injection streams with a tightly focused stream profile and a constant flow angle are formed, as is needed for a direct injection internal combustion engine. Moreover, the offset disposition of the openings relative to the sealing face of the closing head assures that tightly focused injection streams are not formed until after an idle valve needle stroke is traversed at low fuel feed pressure, or low engine speed; such streams assure good fuel preparation. Moreover, an unthrottled inflow to the beginning of the openings is assured by the relatively large cross section that is feasible for the recess on the face end of the piston of the closing head toward the pressure chamber.
By the provisions recited herein advantageous further features of and improvements to the fuel injection nozzle disclosed are possible. The piston of the valve needles in are provided with a particularly low-throttling flow of the fuel to the openings and through them to the injection ports. As a result, very high efficiency in the conversion of pressure into speed is attained. By the alignment of the openings an injection profile of the kind with multi-port nozzles is attained. The injection characteristic is favorably affected by means set forth herein. An embodiment set forth herein assures a defined contact of the sealing face of the closing head with the valve seat of the nozzle body which is especially advantageous. A satisfactory, defined contact of the valve cone with the nozzle body valve seat in the form of the linear seat is attained by the construction set forth.


DRAWING

Two exemplary embodiments of the invention are shown in the drawing and will be described in detail below. FIG. 1 is longitudinal section of an injection nozzle; FIGS. 2 and 3 show the end portion A toward the combustion chamber in the first exemplary embodiment of the injection nozzle of FIG. 1 in cross section and on a larger scale, in the closed and open position, respectively; FIG. 4 shows the end portion A toward the combustion chamber of the second exemplary embodiment, on a larger scale and in cross section; and FIGS. 5a-5d shows shapes of grooves of the second exemplary embodiment of FIG. 4 in a simplified side view.


DESCRIPTION OF THE EXEMPLARY EMBODIMENT

The injection nozzle has a nozzle body 10, which is fi

REFERENCES:
patent: 2183284 (1939-12-01), Weibicke
patent: 2263197 (1941-11-01), Tabb et al.
patent: 4982708 (1991-01-01), Stutzenberger
patent: 5127584 (1992-07-01), Sczomak

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