Fluid sprinkling – spraying – and diffusing – Fluid pressure responsive discharge modifier* or flow... – Fuel injector or burner
Reexamination Certificate
2000-07-07
2001-09-04
Scherbel, David A. (Department: 3752)
Fluid sprinkling, spraying, and diffusing
Fluid pressure responsive discharge modifier* or flow...
Fuel injector or burner
C239S533200, C239S533300, C239S584000
Reexamination Certificate
active
06283389
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a fuel injection improved fuel injection valve for internal combustion engines.
2. Description of the Prior Art
In a fuel injection valves of this type, a piston-shaped valve member is guided so that it can move axially in a bore of a valve body, wherein the end of the valve member oriented toward the combustion chamber has a valve sealing face, which it uses to cooperate with a stationary valve seat provided on the end of the bore oriented toward the combustion chamber in order to control the through flow of fuel to an injection opening that feeds into the combustion chamber of the internal combustion engine. The opening stroke motion of the valve member occurs in opposition to a restoring force, usually the force of a valve spring, by means of a high injection pressure of the incoming fuel that acts on the valve member in the opening direction.
In order to introduce the force of this opening pressure onto the valve member, the valve member has a pressure shoulder that is constituted by an annular step, which protrudes into a pressure chamber formed by means of a cross sectional widening of the bore. With its cross sectionally enlarged shaft part remote from the combustion chamber, the valve member is guided so that it can slide in a sealed fashion in a part of the bore in the valve body which acts as a guide section. This guide section of the valve member thus constitutes a guide surface at the end of the valve member remote from the combustion chamber, which is subjected to a high degree of wear due to its very snug guidance in the bore. Therefore the known fuel injection valves, particularly at very high injection pressures, have the disadvantage that fuel pressure fields build up inside the valve member guide, which transmit one-sided lateral forces onto the valve member and thus, through a one-sided contact of the valve member, cause a one-sided surface pressure between the valve member and the bore guide surface, which leads to a more intense wear that can result in undesired leakage and the destruction of the injection valve.
The German utility model DE 295 04 608 discloses a fuel injection valve for internal combustion engines in which the guide surface between the valve member and the guide bore in the valve body is divided into two separate guide regions. This should prevent a one-sided contact of the valve member against the wall of the guide bore and consequently a one-sided wear. However, the known fuel injection valve has the disadvantage that as a result of the large clearance between the surfaces of the valve member and the guide bore wall between the separate guide regions, a tearing of a lubrication film between the moving components can occur, which once more encourages wear.
SUMMARY OF THE INVENTION
The fuel injection valve for internal combustion engines according to the present invention, has the advantage over the prior art that a tilting of the valve member and consequently a one-sided wear on the guide surfaces can be reliably prevented. This is achieved in an advantageous manner through the provision of one more recesses producing a hydraulic wedge between the valve member and the guide bore in the valve body, and this hydraulic wedge extends over the essential part of the guide surface between the valve member and the bore and therefore hydraulically centers the valve member in the bore. These recesses in the guide surface of the valve member are preferably disposed in substantially even distribution over its circumference so that a uniform pressure compensation on the valve member is produced, which prevents local pressure peaks between the valve member and the guide bore and therefore reliably prevents the one-sided introduction of lateral forces.
These recesses in the guide surface of the valve member can be embodied as grooves, preferably lateral grooves, point indentations, or also as oblique grooves, wherein other forms of recesses are also alternatively possible here. In order to be able to reliably prevent a tearing of the hydraulic oil lubrication film between the moving valve member and the bore wall guiding it, the recesses are provided only in a micrometer range of approx. 1 mm maximally.
With the use of lubrication grooves extending lateral to the axis of the valve member, these are embodied as arched, with a radius, wherein this radius is preferably about 0.1 mm. The lateral grooves in this connection preferably should have a width of approx. 0.16 mm, a maximal depth of approx. 0.03 mm, and a spacing from one another of up to about 1 mm and preferably approx. 0.6 to 0.8 mm, with a valve member diameter of approx. 4 mm in the vicinity of the guide surface.
With the use of a multitude of individual recesses, which thus constitute so-called lubrication pockets, these preferably have a diameter between 0.2 and 0.5 mm and are incorporated into the valve member to a depth of approx. 0.02 to 0.05 mm. The production of these lubrication pockets preferably takes place by means of a laser burning process or by means of rolling them into the circumference surface of the valve member.
Another advantage can be achieved if the recesses in the guide surface of the valve member, which contribute to a hydraulic pressure compensation, are embodied as oblique grooves that encompass approx. 180° of the valve member circumference. These oblique grooves can be embodied in a particularly advantageous manner as helically curved, which has the advantage that with a one-sided contact of the valve member against the guide bore, the higher hydraulic pressure is introduced at the beginning of the helical groove and then conveyed to the contacting side of the valve member. In this connection, the width of the helical groove produces an intensified restoring force which encourages a centering of the valve member in the guide bore.
In the exemplary embodiments described, the hydraulic pressure compensation recesses are incorporated into the circumference surface of the valve member, however it is alternatively also possible to provide these pressure compensation recesses in the wall of the guide bore in the vicinity of the guide surface of the valve member and to produce the same hydraulic centering effective in this manner. Even in this case, the pressure compensation recesses should be disposed in the range of micrometer dimensions in order to reliably prevent a tearing of the lubrication film between the valve member and the bore.
REFERENCES:
patent: 1737985 (1929-12-01), Tursky
patent: 1964218 (1934-06-01), Schargorodsky
patent: 1990875 (1935-02-01), Mock
patent: 3398936 (1968-08-01), Deland
patent: 3425635 (1969-02-01), Guertler
patent: 3581728 (1971-06-01), Abraham
Ganey Steven J.
Greigg Edwin E.
Greigg Ronald E.
Robert & Bosch GmbH
Scherbel David A.
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