HU177228B - Method for direct fuel-injection - Google Patents

Abstract

In air-compressing, direct-injection piston internal combustion engines the action of partially applying the fuel in the form of a film to the combustion chamber wall and partially mixing it directly with the combustion air is already known, it being intended that the former should predominate in the upper speed and load range and the latter in the lower speed and load range. In known engines the distribution between wall application and direct air mixing is performed, for example, as a function of the temperature by adjusting the position of the injection jets and/or the fineness of their atomisation. By contrast, according to the invention a device is provided on the injection nozzle which keeps the fuel injection pressure on the nozzle bore constant or virtually constant over the entire engine operating range. The optimum jet characteristic is thereby maintained in all speed ranges. Wall application is largely avoided in the lower speed and load range because here the penetration capacity of the fuel jet is reduced owing to the shortening of the injection process.

Description

M. A. N. Maschinenfabrik

Augsburg-Nuremberg Aktiengesellschaft, Nuremberg, Federal Republic of Germany

Procedure for Direct Fuel Injection

FIELD OF THE INVENTION The present invention relates to a process for direct injection of fuel into internal combustion engines having a rotary body formed by a piston or cylinder head, in which the inflow air is rotated by known means about the longitudinal axis there it is evaporated, from there it is slowly and gradually separated with the rotating air, stirred and finally burned, while at idle and at the lower engine speed and load range, the fuel is blended as directly as possible with the combustion air.

It has long been known in the case of internal combustion engines working on the application of fuel to the combustion chamber that part of the fuel 1 already injected into the combustion chamber must be directly mixed with the combustion air to start the ignition. Such a solution is described, for example, in U.S. Patent No. 865,683. It is also known that at least 2% of the fuel to be blended directly with air at full engine load, but the total amount injected 2 must be high enough to prevent at least any detectable ignition noise. This is described, for example, in Dutch Patent No. 860.

In recent years, due to increasingly stringent exhaust 2 specifications, and to improve engine starting behavior, it has been found advisable to mix the smaller amounts of injection fuel required at idle and low speed and load range directly with the combustion air 3. In these ranges, for the film-like fuel to evaporate sufficiently quickly, the combustion chamber wall is not hot enough, resulting in imperfect combustion. In contrast, the application of fuel to the combustion chamber in the upper engine speed range and ter5 range is very successful.

If due to the effects of air circulation in the combustion chamber on the distribution of air. ignore eg. (French Patent No. 1276938), the position and shape of the fuel jet are crucial for such a 0-direction change. Thus, it has been suggested, among other things, that the injected fuel should be divided into two variable parts depending on the temperature of the combustion chamber wall or other values, one of which is applied filmically to the combustion chamber wall 5. the other part is mixed directly with air. Alternatively, it is proposed to change the position of the injection jet and / or its atomization fineness in U.S. Patent No. 1,526,324. S German Patent Specification No. 1,252,968, the so-called rotary atomizer. and other suggestions in this regard. Accordingly, for a given ratio of fuel application to the combustion chamber relative to direct air distribution, at each of the operating ranges of the engine, at a given su5 length, besides the cross-sectional effect of the nozzle, the specified fuel jet velocity and injection pressure are determined.

It is an object of the present invention to provide, in the light of the above findings, an internal combustion engine described above with a view to improving the exhaust gas quality and engine data primarily in the lower characteristic curve without impairing this data in the upper characteristic curve.

In accordance with the present invention, the object of the present invention is to maintain the fuel injection pressure at the nozzle bore at a constant or near constant value throughout the engine operating range.

With this action, good blending is achieved throughout the engine operating range and consequently good combustion, which results in good exhaust quality. This maintains the optimum radius characteristic for each speed range. Forced reduction of injection at reduced load or RPM reduces fuel jet penetration. This results in complete avoidance of application to the combustion chamber at idle & low speed and load range - where the amount injected is correspondingly low.

By simply adjusting the injection device to the constant injection rate of the injection dosing element (mm '/ crank angle), which is essentially given by the piston pump diameter and cam track in the delivery range, and by the constant injection nozzle cross-section, the above requirements are not met. Thus, optimum radiation characteristics are always achieved only in a narrow, middle operating range.

In order to control the constant fuel injection pressure in the process of the present invention, it is desirable to supply more fuel than necessary in the nozzle bore and the fuel surplus to maintain a constant fuel injection pressure at the nozzle bore. is returned to the injection pump element.

Another option is to keep the fuel injection pressure constant by injecting the nozzle bore! using a pin nozzle whose nozzle bore cross-section is varied with the variable gauge, the shape of the spigot, and the bore so as to allow direct mixing of the fuel with the combustion air at low fuel injection rates.

Both methods of keeping the injection pressure constant can be achieved by means known in the art and are therefore not described in further detail herein. Otherwise they can be used individually or together.

Finally, for the sake of completeness, it is mentioned that in the last mode of control, the control of the nozzle stroke is directly dependent on the fuel injection pressure and indirectly on the variable stroke limiter, which, in turn, depends on the injection pressure or

Claims (2)

15 and / or motor load. Patent claims: 20 1- Method for Direct Fuel Injection for Internal Combustion Engines with Air-Piston, Cylinder or Cylinder Head Rotary Body Combustion, wherein the inlet combustion air is rotated about the longitudinal axis of the combustion chamber, the fuel in the upper revolution numerical range and the load range; evaporating there, then slowly separating it with the rotating air, mixing it and finally burning it, while at idle and at the lower engine speed and load range, the fuel is directly mixed with the combustion air, with the fuel injection pressure directly at the nozzle bore is kept constant or close to constant. 2. The method of claim 1, wherein at the nozzle bore, more fuel than necessary is delivered from the injection pump element to the injection nozzle to maintain a constant fuel injection pressure, and the excess fuel is provided in the nozzle bore, it is led back to the injection pump element through a sealable outlet.