WO2005113977A1

WO2005113977A1 - Injection valve for internal combustion engines

Info

Publication number: WO2005113977A1
Application number: PCT/EP2005/052144
Authority: WO
Inventors: Günter LEWENTZ; Johann Massinger
Original assignee: Siemens Aktiengesellschaft
Priority date: 2004-05-17
Filing date: 2005-05-11
Publication date: 2005-12-01
Also published as: DE102004024389A1

Abstract

The invention relates to an injection valve, comprising a body with an end surface (20) to the body and at least one passage (21) of the body, opening in the end surface (20) of the body and a second body with a second end surface, facing the end surface (20) of the body and at least one second passage, opening in the second end surface of the second body, communicating with the passage (21) of the body. A sealing disc (6), arranged in a sealing manner on the end surface (20) of the body and the second end surface of the second body, has a thickness of less than one millimetre and has at least one passage (22) in the sealing disc (6), through which the passage (21) of the body and the second passage of the second body can communicate. A clamping device presses the body, the sealing disc (6) and the second body together.

Description

description

Injection valve for internal combustion engines

The combustion processes in internal combustion engines, particularly in motor vehicles, are dependent on the mixture preparation of the air / fuel mixture. Improving the mixture preparation is necessary in order to be able to meet the requirements for high performance, low fuel consumption, low exhaust gas emissions and smooth running of the internal combustion engine. There is only a very short period of a few milliseconds available for the mixture preparation, especially at high speeds, in which the fuel must be metered in and mixed with the air before the ignition takes place. In order to be able to ensure a good mixture preparation of the air / fuel mixture under these conditions, the fuel, for example diesel fuel, is injected during direct injection into the combustion chambers of the internal combustion engine under very high pressure, for example more than 1500 bar.

Injection valves are usually composed of several bodies, which usually adjoin one another in the axial direction. Bores and / or recesses are made in the bodies which, depending on their task, can extend through more than one body. Bores for receiving a nozzle needle and bores for supplying fuel are provided. So that the fuel under high pressure cannot escape from the bores and / or recesses between the bodies of the injection valve, the contact surfaces of the bodies must be made very precisely on the one hand and the bodies must be pressed onto one another with a high contact pressure. The processing of the contact surfaces of the body is complex and expensive.

The object of the invention is to provide an injection valve that is simple and inexpensive to manufacture. The object is achieved by the features of the independent claims. Advantageous developments of the invention are characterized in the subclaims.

The invention is characterized by an injection valve which comprises a first body with a first end face and at least one first recess opening into the first end face of the first body and a second body with a second end face which faces the first end face of the first body, and at least one second recess opening into the second end face of the second body and communicating with the first recess of the first body. A sealing washer has a first surface, which is arranged sealingly to the first end face of the first body, and a second surface, which is arranged sealingly to the second end face of the second body, in which the ^{distance of} the second surface from the first surface is smaller is than a millimeter. The sealing disk has at least one recess through which the first recess in the first body and the second recess in the second body can communicate. The wall of the at least one recess in the sealing disk sealingly surrounds the first recess in the first body and the second recess in the second body. A clamping device presses the first body, the sealing washer and the second body together.

By using the sealing washer, complex machining of the first end face of the first body and / or the second end face of the second body can be dispensed with. Nevertheless, it is possible to achieve a very good sealing effect in a simple manner. The sealing washer is simple and inexpensive to manufacture and can be replaced if necessary.

In an advantageous embodiment of the injection valve, the sealing disk is designed such that the first surface and the second surface is small from the first end surface of the first body and the second end surface of the second body. The first surface and the second surface of the sealing disk are essentially formed only where the sealing effect is to be achieved, that is to say essentially around the recesses and / or bores, for example, which carry fuel under high pressure. If necessary, the sealing washer is also formed in the outer edge region of the body. This can prevent, for example, dirt or moisture from penetrating, which can promote corrosion and reduce the durability of the injection valve. Furthermore, the stability can be improved.

Forming the sealing washer essentially only where the sealing effect is required has the advantage that the contact areas between the first end face of the first body and the first surface of the sealing washer and between the second surface of the sealing washer and the second end face of the second body are very small can be formed so that a larger contact pressure, and thus a better high pressure tightness, can be achieved.

In a further advantageous embodiment of the injection valve, the sealing disk is a sheet metal. This has the advantage that the sealing washer can be manufactured so easily and cheaply.

In a further advantageous embodiment of the injection valve, the sealing disk is a film. A film can be produced easily and cheaply and also has a very low overall height.

In a further advantageous embodiment of the injection valve, the sealing washer is formed at least in two layers. This has the advantage that it is possible to combine layers with different properties and to coordinate them accordingly can. Different materials can be used, for example with different hardness.

In this context, it is advantageous if the sealing disc comprises a carrier layer and at least one compensation layer and the at least one compensation layer comprises the first and / or the second surface of the sealing disc. The carrier layer consists of a harder material than the at least one compensation layer. The advantage is that the properties of high strength, for high-pressure security, and compensation of unevenness in the sealing disk can be combined, which can reduce the requirements on the first end face of the first body and the second end face of the second body and improve the sealing effect can. The hard carrier layer can be designed to withstand the high pressure. In contrast, the soft compensation layer is easier to deform, so that bumps and fine dirt particles can be embedded in the compensation layer, which can no longer impair the high-pressure tightness.

In a further advantageous embodiment of the injection valve, elevations and / or depressions are formed in the first surface and / or the second surface of the sealing disk, so that only a part of the first surface seals against the first end surface of the first body and / or the second surface to the second end surface of the second body. This enables the sealing surface to be further reduced and thus improves the high-pressure tightness. Unevenness can also be better compensated for.

In a further advantageous embodiment, the distance between the first surface and the second surface of the sealing washer is less than 0.1 millimeter. This has the advantage that the sealing washer is well supported between the first body and the second body, so that the sealing washer is not deformed by the high pressures and thus the high pressure tightness can be ensured. Furthermore, a very even distribution of the contact pressure is possible due to very small deviations in the thickness of the sealing washer, since the sealing washer can be manufactured very precisely. The low overall height of the sealing washer is also advantageous.

In a further advantageous embodiment of the injection valve, the sealing disk consists of a softer material than the first and / or the second body. This has the advantage that the easier deformability of the softer material makes it possible to compensate for unevenness and to embed fine dirt particles in it, so that these cannot impair the high-pressure tightness. The surface finish requirements of the first end surface of the first body and the second end surface of the second body can be reduced. As a result, the injection valve can be manufactured more easily and more cheaply.

Embodiments of the invention are explained below with reference to the schematic drawings. Show it:

1 shows a longitudinal section through an injection valve, FIG. 2 shows a top view of a first embodiment of the sealing disk, FIG. 3a shows a top view of a second embodiment of the sealing disk, FIG. 3b shows a section through the second embodiment of the sealing disk, FIG. 4a shows a top view of a third embodiment shape of the sealing washer, and Figure 4b shows a section through the third embodiment of the sealing washer.

Elements with the same function are provided with the same reference symbols in all figures. FIG. 1 shows a part of an injection valve which comprises a valve body 1, an injector body 2, a stop disc 3, a nozzle body 4, a nozzle clamping nut 5 and sealing discs 6. The sealing disks 6 are arranged between the valve body 1 and the injector body 2, the injector body 2 and the stop disk 3 and between the stop disk 3 and the nozzle body 4. The nozzle clamping nut 5 encloses and fixes the bodies and disks and presses them together.

The injection valve further comprises a high-pressure bore 7, a high-pressure chamber 8, a throttle 9 and a control chamber 10, which are communicatively connected to one another. The high-pressure bore 7 conducts fuel under high pressure both into the high-pressure chamber 8 and through the throttle 9 into the control chamber 10.

Furthermore, the injection valve comprises a piezo actuator 11, a valve piston 12, a valve mushroom 13 and a valve spring 14, which adjoin one another axially. The piezo actuator 11 acts on the valve piston 12 in the axial direction. The valve piston 12 acts on the valve mushroom 13, which lifts it from a valve seat when the piezo actuator 11 is actuated in such a way that it extends axially. The fuel can then flow out of the control chamber 10 into a low-pressure circuit.

If the piezo actuator 11 is controlled such that it shortens axially, the valve spring 14 presses the valve mushroom 13 against the valve seat and thus blocks the outflow of fuel from the control chamber 10, so that the high-pressure bore 7 and the throttle 9 in the control chamber 10 build up a high fuel pressure.

The injection valve further comprises a control piston 15, a nozzle needle 16 and an injection nozzle 17. The control piston 15 is connected to the nozzle needle 16. The fuel pressure in the control chamber 10 acts on the end face of the control piston 15, so that the nozzle needle 16 is pressed in the axial direction against a valve seat in the nozzle body 4 and closes the injection nozzle 17.

If the piezo actuator 11 is controlled in such a way that it lengthens axially, then the pressure in the control chamber 10 drops due to the outflow of fuel into the low-pressure circuit, and the nozzle needle 16 becomes pressurized due to the high fuel pressure on the edges of the nozzle needle 16 in the high-pressure chamber 8 and acts on the tip of the nozzle needle 16, lifted off the valve seat. The fuel then flows through the injection nozzle 17 into the combustion chamber of a cylinder of an internal combustion engine.

If the piezo actuator 11 is controlled so that it shortens axially, then a high fuel pressure can build up again in the control chamber 10, so that the control piston 15 moves the nozzle needle 16 back into the position in which the injection nozzle 17 is closed. A nozzle spring 18 prevents fuel metering when there is insufficient fuel pressure, for example during breaks in operation of the internal combustion engine. A drain hole 19 leads fuel penetrating into the area of the nozzle spring 18 into the low-pressure circuit.

Figure 2 shows the sealing washer 6, which is applied to an end face 20 of a body. The body is, for example, the valve body 1, the injector body 2, the stop disk 3 or the nozzle body 4 and the end surface 20 of the body is the surface of the body which in each case adjoins one of the other bodies, for example between the valve body 1 and the injector body 2, between Injector body 2 and stop disc 3 or between stop disc 3 and nozzle body 4. The injection valve can also include more or fewer bodies and discs than the valve body 1, the injector body 2, the stop disc 3 and the nozzle body 4. A plurality of bores and / or recesses 21 of the body open into the end face 20 of the body, which, for example, can hold centering pins for aligning and fixing the position of two bodies of the injection valve relative to one another, the nozzle needle 16 or other elements of the injection valve, or fuel under high pressure direct the body of the injector.

The sealing disk 6 has a plurality of recesses 22. The recesses 22 of the sealing disk 6 are introduced into the sealing disk 6 in accordance with the bores and / or recesses 21 of the body. Further recesses 22 are preferably made in the sealing disk 6, which reduce a contact area between the sealing disk 6 and the end face 20 of the body and between the sealing disk 6 and a second end face of a second body, which is not shown in FIG. 2.

The sealing disk 6 essentially surrounds only the high-pressure-carrying recesses 21 of the body in order to seal them in the radial direction. Crosspieces 23 can be formed in the sealing disk 6, which connect the various sealing regions of the sealing disk 6 which are formed around the recesses 21 of the body. If necessary, webs 23 can also be formed in the outer region of the sealing disk 6 along the outer edge, as shown in FIG. 2. This can increase stability and in particular can prevent the ingress of dirt, moisture or corrosive substances, which can reduce the durability and reliability of the injection valve. Furthermore, the handling of the sealing disk 6 can be improved without significantly increasing the contact area.

The sealing disk 6 can be designed as a thin sheet or a thin film, the thickness of which is less than 1 millimeter, for example 0.2 millimeters, and preferably small. is less than 0.1 millimeters. The sealing disk 6 can be produced, for example, by fine stamping, by laser or water jet cutting or similar processes. Electrochemical processes are also suitable, for example electrochemical machining, which is also referred to as the ECM process. In particular, the bipolar ECM method is suitable for forming very fine structures in the sealing disk 6.

Figure 3a shows the sealing washer 6 with two recesses 22 of the sealing washer 6 and the web 23. Figure 3b shows a section through the sealing washer 6, which comprises three layers. A compensation layer 25 is applied in each case to a carrier layer 24 on the top and the bottom of the sealing disk 6. The compensation layers 25 comprise a first surface 26 of the sealing washer 6 and a second surface 27 of the sealing washer 6, which are intended to form the sealing contact surfaces.

The carrier layer 24 is preferably made of a solid material, for example of hard, high-strength steel, which gives the sealing disk 6 the required strength. The compensation layers 25 are preferably made of a softer material such as nickel, which due to its high deformability can compensate for unevenness and embed fine dirt particles. The compensation layers 25 can be applied to the carrier layer 24, for example by galvanic deposition, a few micrometers thick. Due to the small thickness of the compensation layers 25, when the bodies and the sealing washer 6 are pressed together, they are well supported by the bodies, which are preferably made of a harder material, and the carrier layer 24, so that the high-pressure tightness is not impaired. Due to the soft compensation layer 25, the demands on the surface quality of the end face 20 of the body or the second end face of the second body can be reduced, since unevenness and greater roughness of the surface can be compensated for by deformation of the compensation layer 25.

The sealing disk 6 can also comprise fewer or more than three layers. The number and the properties of the layers can be selected depending on the respective requirements. For example, a single layer can be sufficient, especially if it fulfills the requirements regarding strength and deformability. A two-layer structure of the sealing disk 6 can be advantageous if, for example, the adjoining and to be sealed bodies are made of different materials or the surface properties of the end faces of the bodies are different.

A hardness range for the sealing disk 6 between 30 and 50 according to the Rockwell hardness scale C has proven to be advantageous. In this hardness range there is both high strength and sufficient ductility. The selection of the material for the sealing disk 6 and its hardness must be selected depending on the respective application. Furthermore, the materials of the body adjoining the sealing disk 6 and their hardness must be taken into account. In general, it is advantageous to manufacture the sealing disk 6 from a softer material than the body. However, the sealing disk 6 must have a sufficiently high strength so that it is not pressed out between the bodies by the high pressures. Due to the small thickness of the sealing washer 6, the deformation of the sealing washer 6 can be counteracted due to the supporting action by the adjacent body made of harder materials.

In Figure 4a, the sealing washer 6 is shown with two recesses 22 of the sealing washer 6 and the web 23. FIG. 4b shows a section through the sealing disk 6 shown in FIG. 4a. In the first surface 26 of the sealing disk 6 and the second surface 27 of the sealing disk 6 are elevations and Recesses are formed, which are arranged so that they each surround the recesses 22. In Figure 4a, this is shown by the self-contained lines in the sealing disk 6, which enclose the recesses 22 of the sealing disk 6. Only a part of the first surface 26 of the sealing disk 6 or the second surface 27 of the sealing disk 6 are in contact with the end face 20 of the body or the second end face of the second body. This reduces the effective contact area between the sealing washer 6 and the end face 20 of the body and / or between the sealing washer 6 and the second end face of the second body. The elevations and / or depressions can, for example, be embossed into the sealing disk 6. The elevations are preferably only a few micrometers high and the depressions are only a few micrometers deep.

The injection valve has the advantage that a smaller contact pressure and thus an improved high-pressure tightness can be achieved by reducing the effective sealing surfaces with the same clamping force. The sealing surfaces can be worked out very finely in the sealing disk 6, even under the conditions of mass production. The sealing effect can be produced locally where it is needed, in particular where fuel is to be conducted under high pressure. Furthermore, the requirements for the smoothness of the end face 20 of the body and the second end face of the second body can be reduced, since the sealing disk 6 is able to compensate for unevenness by its structure and / or by the appropriate choice of a suitable material. The sealing discs 6 can be easily and cheaply produced in large quantities.

Claims

claims

1. Injector that includes

a first body with a first end face and at least one first recess opening into the first end face of the first body,

a second body with a second end surface facing the first end surface of the first body and at least one second recess opening into the second end surface of the second body and communicating with the first recess of the first body,

- A sealing washer (6) with a first surface, which is arranged sealingly to the first end face of the first body, and a second surface, which is arranged sealingly to the second end face of the second body, in which the distance of the second surface from the first Surface is less than one millimeter and has at least one recess through which the first recess m can communicate with the first body and the second recess in the second body and the wall of the at least one recess has the first recess in the first body and the second Sealingly encloses recess in the second body, and

- A tensioning device that presses the first body, the sealing washer (6) and the second body together.

2. Injector according to claim 1, wherein the sealing washer (6) is formed such that the first surface and the second surface are small compared to the first end surface of the first body and the second end surface of the second body.

3. Injector according to claim 1 or 2, wherein the sealing washer (6) is a sheet.

4. Injector according to claim 1 or 2, wherein the sealing disc (6) is a film.

5. Injector according to claim 1 or 2, wherein the sealing disc (6) is at least two layers.

6. Injection valve according to claim 5, wherein the sealing disc (6) comprises a carrier layer (24) and at least one compensation layer (25) and the carrier layer (24) consists of a harder material than the compensation layer (25) and the compensation layer (25) comprises the first and / or the second surface of the sealing washer (6).

7. Injection valve according to one of the preceding claims, in which elevations and / or depressions are formed in the first surface and / or the second surface of the sealing disk (6) and only a part of the first surface sealing to the first end surface of the first body and / or the second surface is arranged sealingly to the second end surface of the second body.

8. Injection valve according to one of the preceding claims, wherein the distance between the first surface and the second surface of the sealing washer (6) is less than 0.1 millimeter.

9. Injection valve according to one of the preceding claims, wherein the sealing disc (6) consists of a softer material than the first and / or the second body.