DE10351460A1 - Fuel injection device, and method for its production - Google Patents

Abstract

A fuel injection device comprises a housing (22) and a valve element (30) arranged in the housing (22). This may separate or connect a fuel exit port (28) from a high pressure port. It has a sealing area (44) which is formed between two wall surfaces (38, 42) which enclose an angle of <180 °. The sealing region (44) cooperates with a housing-side and opposite valve seat surface (26). It is proposed that the sealing area (44) is rounded.

Description

The Invention relates first a fuel injection device, especially for an internal combustion engine with direct fuel injection, with a Casing, and at least one valve element arranged in the housing, which at least one fuel outlet opening from a high pressure port can disconnect or connect to this and which a sealing area having formed between two wall surfaces which enclose an angle <180 ° is and with a housing-side and the sealing area in approximately opposite valve seat surface cooperates.

The The invention further relates to a method for producing such Fuel injector.

A fuel injection device of the type mentioned is from the DE 101 22 256 A1 known. It is used there in a common rail fuel system for the direct injection of fuel into a combustion chamber of an internal combustion engine. For this purpose, a longitudinally movable valve element is accommodated in a housing. Depending on the position of the valve element, fuel outlet openings, which face the combustion chamber, are connected to or disconnected from a high-pressure connection. For this purpose, the combustion chamber facing the end of the valve element is conical. The conical end region has two sections with different conicity. There is a sharp discontinuity between the two areas, so that a sharp sealing edge is formed there. With this sealing edge, the valve element is in the closed state at a sealing surface opposite the flat valve seat surface of the housing.

The The present invention has the object of a fuel injection device and to develop a method of the type mentioned at the outset, that the fuel injector a longer one Life with even better sealing effect. Furthermore Their production should be simplified as a whole.

These Task is in a fuel injection device of the aforementioned Sort of solved by that the sealing area is rounded.

at a method of the type mentioned, the task is characterized solved, that the sealing area is made so that it is rounded.

Advantages of invention

The Fuel injection device according to the invention points opposite usual Fuel injectors on a longer life, as the Wear in the Area of the valve seat is reduced. The reason is in that the opposite Valve seat with the valve element closed tangentially to the rounded sealing area is applied, resulting in a better sliding of the valve element during closing or opening. This "slips" especially when Shut down the valve element easier in the corresponding valve seat on the housing. Already This reduces the wear.

immediate after the manufacture of the fuel injection device is the rounded sealing area line on the opposite valve seat surface. After a short period of operation results from the inevitable deformation on the one hand on the sealing area and on the other hand on the opposite side Valve seat due to the existing rounding an at least partially planar contact between the valve member and the opposite valve seat surface, which leads to a "flat" wear, the overall opposite usual Fuel injectors is reduced.

by virtue of the rapidly adjusting and with closed valve element at least partially flat Contacting between the valve element and the valve seat surface is it possible, the so-called seat angle difference, ie the angle between the enclosed with both adjacent to the sealing area upper wall surfaces becomes very big do. This simplifies the production and allows the realization greater Diameter in the region of the injection ends of the valve element and of the housing, without thereby a greater wear or a to fear reduced sealing effect would.

advantageous Further developments of the invention are specified in subclaims.

at a fuel injection device according to the invention It is proposed that the sealing area is rounded in such a way that the wall surfaces on both sides of the sealing area without edge to the sealing area connect. So there are any edges in this area of the valve element avoided. this leads to For a particularly low wear and a long life the fuel injector.

It is particularly preferred if the Dichtbereicht with a radius of about 0.1 to 0.4 mm, more preferably with a radius of 0.15 to 0.3 mm is rounded. Such curves are easily produced by conventional grinding machines or grinding devices, and they lead to the full extent to the advantages described above.

The Valve element can easily have multiple sealing areas, without this leading to significant additional costs during production. Here makes the fact according to the invention, that during it of the initial one Operation of the fuel injection device according to the invention a uniform flattening comes at the sealing area, particularly noticeable, since this already After a short time all sealing areas show a uniform good sealing behavior.

A particularly advantageous embodiment of the method according to the invention is characterized in that the at least one sealing area and the adjacent to the sealing area wall surfaces in one operation a single, appropriately profiled grinding tool can be edited. As a result, a particularly inexpensive production of the fuel injection device according to the invention allows.

Compared to conventional Fuel injection devices, which are to the sealing area adjacent wall surfaces in separate grinding operations be processed, the inventive measure allows a considerable rationalization and also a time saving in production. Such an integral Production of the sealing area and the adjacent wall surfaces was so far not possible, since the previously required sharp sealing edges are not realized could become. Only due to the fact that a rounded sealing area Consciously admitted, this can be particularly cost-effective integral Manufacturing process selected become.

Just even with complex geometries, where a particularly high manufacturing accuracy (in the micrometer range) is required, this high accuracy be realized because it is no longer necessary, the grinding tool repeatedly approach the blank or again from this move away. A one-time bringing the tool is sufficient. Of Furthermore, it has a positive effect in the method according to the invention that Tolerances or inaccuracies of a dressing machine, with which The grinding tool is always brought to measure, only a little on the accuracy of the measurements affect the valve element. The reason for this is that at least the smaller errors of such a dressing machine on all manufactured surfaces transferred the valve element in the same way. This results again from the fact that the dressing machine to the grinding tool only once and then move it to the contour of the grinding tool. or leaves. hereby is due to the inaccuracy of the dressing system ultimately on the valve element caused error in all machined areas of the valve element, So on all wall surfaces and sealing areas, the same size and at least theoretically rises relative to a region of the valve element others completely on.

This is particularly advantageous for very small seat angle difference or if the provided gap between the valve element and the housing are very low. Thereby, that the axial position of the sealing area is given by the profile of the grinding tool is also the axial position of the valve element in the housing in the closed state set with high accuracy and varies from one copy a fuel injection device on the other hand, only a little. Thanks to the method according to the invention is therefore the Extent of Specimen discrepancies diminished.

drawing

following become particularly preferred embodiments the present invention with reference to the accompanying Drawing closer explained.

In show the drawing:

1 a schematic representation of an internal combustion engine with a plurality of fuel injection devices;

2 a partial section through an area of one of the fuel injectors of 2 ;

3 a detail III of 2 ;

4 an enlarged side view of a valve element of the fuel injection device of 2 with a profiled grinding tool for its production;

5 a representation similar 4 a second embodiment of a valve element and the corresponding grinding tool;

6 a detail VI of 5 ;

7 a representation similar 4 a third embodiment of a valve element and the corresponding grinding tool;

8th a partial section through a fourth embodiment of a valve element; and

9 a detail IX of 8th ,

description the embodiments

An internal combustion engine carries in 1 Overall, the reference number 10 , It includes a fuel storage tank 12 from which a conveyor 14 the fuel to a fuel rail 16 ("Rail") promotes. The latter are several fuel injectors 18 connected to each of the fuel in a directly assigned combustion chamber 20 inject.

How out 2 in detail, includes a fuel injector 18 a housing 22 in which a recess with a cylindrical section 24 and a tapered section 26 is available. The conicity of the conical section 26 is consistent. In the area of the conical section 26 becomes the case 22 from a series of fuel exit channels 28 interspersed.

In the recess 24 . 26 in the case 22 is an elongated valve element 30 used. This comprises a cylindrical main section 32 and a generally conically tapered end portion 34 , The cylindrical main section 32 has a diameter that is slightly smaller than the inside diameter of the cylindrical section 24 the recess in the housing 22 , In this way, between the valve element 30 and the housing 22 an annulus 36 formed on in 2 not shown manner is connected to a high pressure port, in turn to the fuel rail 16 connected.

The conical end section 34 of the valve element 30 has two wall surfaces with different conicity (compare also 3 ). An in 2 upper wall surface 38 closes with a longitudinal axis 40 of the valve element 30 a smaller angle than the conical section 26 the recess in the housing 22 , An in 2 lower conical wall surface 42 on the other hand closes with the longitudinal axis 40 a larger angle than the conical section 26 the recess in the housing 22 ,

How very good 3 is apparent, is between the two conical areas or wall surfaces 38 and 42 of the valve element 30 a rounded sealing area 44 available. Like also out 3 it can be seen, it is the rounded sealing area 44 in a side sectional view around a circumferential segment of a circle 46 with the radius R. The position of a center 48 of the circle 46 is chosen so that in the wall surface of the conical end portion 34 of the valve element 30 at least immediately after its production with respect to the slope no discontinuity (ie no edge) is present. The transitions between the circle 46 and the adjacent wall surfaces 38 and 42 are in the 2 and 3 dotted drawn. They bear the reference numbers 50 and 52 ,

In operation prevails in the annulus 36 that high fuel pressure, which is also present in the fuel rail 16 prevails. When the valve element is closed, the rounded sealing area lies 44 at the opposite area 26 the recess in the housing 22 at. This thus forms a valve seat surface. This is the connection between the annulus 36 and the fuel exit channels 28 interrupted. When fuel in the combustion chamber 20 is to be injected, the valve element 30 in a manner not shown here moves upwards. This has the consequence that the rounded sealing area 44 from the opposite valve seat surface 26 takes off. Thus, fuel can be under high pressure from the annulus 36 to the fuel exit channels 28 stream and into the combustion chamber 20 reach.

Immediately after the production of the fuel injection device 18 is the contact between the rounded sealing area 44 and the opposite valve seat surface 26 still linear. In the course of the initial operation of the fuel injector 18 However, it comes in this area to unavoidable wear and deformation, which over time to an at least partially flat contact between the rounded sealing area 44 and the valve seat surface 26 leads.

How out 4 is apparent, is used to manufacture the valve element 30 a profiled grinding tool 52 used. This has two substantially straight areas 54 and 56 on, each exactly parallel to the desired final shape of the wall surfaces 42 and 38 are. Between the two straight surfaces 54 and 56 there is a rounded transition area 38 whose radius of curvature is exactly the desired radius of curvature of the rounded sealing area 44 equivalent. With this grinding tool 52 becomes the conical end section 34 of the valve element 30 processed. In this way, the wall surfaces 38 and 42 and the intermediate rounded sealing area 44 in one operation with a single grinding tool 52 getting produced.

An alternative embodiment of a valve element 30 is in the 5 and 6 shown. Here and in the following figures applies that such elements and areas, which have equivalent functions to previously described elements and areas, the same reference numerals. They are not explained again in detail.

The conical end section 34 in the 5 and 6 shown valve element 30 has a much more complex geometry than the conical end section 34 in the 2 to 4 shown valve element 30 , So is below the rounded sealing area 44 to the conical wall surface 42 towards a circumferential groove 60 available. This serves primarily to optimize the flow behavior when the valve element is open 30 , Also, the transition of the groove 60 to the conical wall surface 42 is rounded. The corresponding transitional area contributes to the 5 and 6 the reference number 62 , Also the conical end section 34 of the valve element 30 comes with a single grinding tool 52 edited in one operation. For this purpose, the grinding tool 52 between the two straight surfaces 54 and 56 one of the groove 60 corresponding bulge 64 and one corresponding to the transition area 62 trained rounding 66 on.

A further modified embodiment shows 7 , This one is also above the conical wall surface 38 arranged cylindrical shoulder 68 from the grinding tool 52 processed. For this purpose, the grinding tool 52 a corresponding straight surface 70 and a transitional round 72 on. The latter becomes a rounded transition 74 between the cylindrical approach 68 and the conical wall surface 38 created.

The 8th and 9 relate to a fuel injection device, which two mutually coaxial valve elements 30a and 30b has, each associated with their own fuel outlet channels. The inner valve element 30b is in the outer valve element 30a slidably guided and fluid-tight. Such a fuel injection device allows the release of different injection cross sections, depending on the amount of fuel to be injected. It may be desirable on the outer valve element 30a to realize a so-called "double seat". This is understood to mean that the outer valve element 30a the valve seat surface 26 (see 9 ) with two axially spaced sealing areas 44a and 44b touched. To realize this, the end section is 34 of the outer valve element 30a executed as follows:
To the upper conical wall area 38 closes the first rounded sealing area 44a on, with the valve element closed 30a on the housing-side valve seat surface 26 is applied. Below the first sealing area 44a is an axially comparatively short straight conical wall surface 42a present, which has a greater taper than the wall surface 38 and has a rounded transition area 62 in the groove 60 passes. This again goes by means of the second rounded sealing area 44b in the lower conical wall surface 42 above. Also the processing of the end section 34 in the 8th and 9 shown valve element 30b takes place in a single operation with a single grinding tool, which in the 8th and 9 however not shown.

Claims (7)

Fuel injection device ( 18 ), in particular for an internal combustion engine ( 10 ) with direct fuel injection, with a housing ( 22 ), and at least one in the housing ( 22 ) arranged valve element ( 30 ), which has at least one fuel outlet ( 28 ) can be separated from or connected to a high-pressure connection and which at least one sealing area ( 44 ), which between two wall surfaces ( 38 . 42 ), which enclose an angle <180 °, is formed and with a housing-side and the sealing area ( 44 ) in approximately opposite valve seat surface ( 26 ) cooperates, characterized in that the sealing area ( 44 ) is rounded. Fuel injection device ( 18 ) according to claim 1, characterized in that the sealing area ( 44 ) is rounded so that the wall surfaces ( 38 . 42 ) on both sides of the sealing area ( 44 ) without edge to the sealing area ( 44 ) connect. Fuel injection device ( 18 ) according to one of claims 1 or 2, characterized in that the sealing area ( 44 ) is rounded with a radius of about 0.1 to 0.4 mm, more preferably with a radius of 0.15 to 0.3 mm. Fuel injection device ( 18 ) according to one of the preceding claims, characterized in that the valve element ( 30a ) several sealing areas ( 44a . 44b ) having. Method for producing a fuel injection device ( 18 ), in particular for an internal combustion engine ( 10 ) with direct fuel injection, with a housing ( 22 ), and at least one in the housing ( 22 ) arranged elongated valve element ( 18 ), which has at least one fuel outlet ( 28 ) can be separated from or connected to a high-pressure connection and which at least one sealing area ( 44 ), which between two wall surfaces ( 38 . 42 ), which enclose an angle <180 °, is formed and with a housing-side and the sealing area ( 44 ) in approximately opposite valve seat surface ( 26 ) cooperates, characterized in that the sealing area ( 44 ) is made so that it is rounded. Method according to claim 5, characterized in that the at least one sealing region ( 44 ) and to the sealing area ( 44 ) adjacent Wall surfaces ( 38 . 42 ) in a single operation with a single, correspondingly profiled grinding tool ( 52 ) to be edited. Method according to claim 6, characterized in that a plurality of sealing areas ( 44a . 44b ) on the valve element ( 30a ) and the corresponding adjacent wall areas ( 38 . 42 ) in a single operation with a single, correspondingly profiled grinding tool ( 52 ) to be edited.