EP1346146A2

EP1346146A2 - Injector for an internal combustion engine

Info

Publication number: EP1346146A2
Application number: EP01985803A
Authority: EP
Inventors: Uwe Lingener; Marion Braun; Jürgen Rink
Original assignee: Siemens AG
Current assignee: Siemens AG
Priority date: 2000-12-27
Filing date: 2001-12-20
Publication date: 2003-09-24
Anticipated expiration: 2021-12-20
Also published as: DE50103161D1; WO2002052147A3; EP1346146B1; DE10065437A1; WO2002052147A2

Abstract

An injector for an internal combustion engine comprises a cylindrical injector body and a nozzle body (4) which is mounted on the injector body. A sealing ring (2) is located on a section (2) of the nozzle body. An essentially ring-shaped projection (30) is located in the area of this section (2) of the nozzle body (2), said projection encompassing at least sections of an outer peripheral surface (31) of the sealing ring (28).

Description

description

Injector for an internal combustion engine

The present invention relates to an injector for an internal combustion engine according to the preamble of claim 1.

For the fuel supply of internal combustion engines, feeder injection systems are increasingly being used, in which a very high injection pressure is used. Such injection systems are known as common rail systems (for diesel engines) and HPDI injection systems (for gasoline engines). In these injection systems, the fuel is pumped with a high-pressure pump into a pressure accumulator common to all cylinders of the engine, from which the injectors on the individual cylinders are supplied with fuel. Here, an injector is usually inserted into a receiving bore in a cylinder head of the internal combustion engine to be supplied with fuel. The receiving bore opens into the combustion chamber of the internal combustion engine, so that the fuel can be injected directly into the combustion chamber via the injector. To seal the bore area of the receiving bore on the combustion chamber side, it is known to place a sealing ring on a nozzle body of the injector, the sealing ring being located between an annular shoulder on the outer circumference of the

Injector and the cylinder head is clamped.

Such an injector, which is used as a fuel injection valve, is known, for example, from EP 0 418 271 B1 and has a cylindrical valve body, the outer diameter of which decreases with the formation of a ring shoulder in the direction of an injection opening of the fuel injection valve. Here, the valve body is clamped axially against a holding body by means of a clamping nut acting on the ring shoulder and inserted into a stepped receiving bore in the housing of the internal combustion engine, the section of which is smaller in diameter and into the combustion chamber of the internal combustion engine. engine opens. The combustion chamber-side bore area of the receiving bore in the housing of the internal combustion engine is sealed by means of a sealing ring clamped between the ring end face of the clamping nut and the housing shoulder of the receiving bore. When dismantling the fuel injection valve from the housing of the internal combustion engine, however, the problem arises that the sealing ring remains in the receiving bore in the housing, ie the cylinder head, of the internal combustion engine and can only be removed from it again with great effort.

To facilitate disassembly it is known from DE 196 05 956 AI to arrange the sealing ring axially secured on the stem of the valve body, so that the sealing ring can be removed from the receiving bore together with the valve body of the injection valve. For this purpose, the sealing ring is fastened to the valve body stem by means of a frictional engagement, the frictional engagement preferably being built up only in partial regions which are distributed symmetrically over the circumference. These subareas are provided by three radially inward projections on the inner wall surface of the sealing ring, which are pressed onto the valve body stem. However, only a small clamping force can be achieved between the sealing ring and the stem by means of the integrations, so that the sealing ring can automatically detach from the stem of the valve body.

For secure fastening, it is known from DE 198 34 475 AI to provide a sealing ring with a central opening which, after being pushed over the shaft part of the valve body, can be deformed in a defined manner. After being pushed over the shaft part, the sealing ring is deformed with a pressing tool in such a way that a material flow to the shaft part is created. In this way an unintentional loosening of the sealing ring from the shaft part is avoided. However, after being attached to the shaft part, the sealing ring is deformed in such a way that it can no longer be removed from the injection valve undamaged. Furthermore, an exchange of the fixed with the Shaft part of the injector connected to the sealing ring without damage to the injector of the injector is difficult to reach.

In view of these disadvantages of the injectors for internal combustion engines known in the prior art, the object of the invention is to provide an injector in which the sealing ring is securely attached to the injector on the one hand and can be replaced quickly and easily on the other hand.

This object is achieved by an injector with the features of claim 1.

Accordingly, an essentially ring-shaped projection is arranged in the area of a nozzle body section of the injector according to the invention for an internal combustion engine, and surrounds a section of an outer circumferential surface of the sealing ring. Here, an inner circumferential surface of the annular projection forms a holding contour for the essentially disk-shaped sealing ring. The holding contour is adapted to the outer circumferential surface of the sealing ring in such a way that the sealing ring is fitted in the region of the nozzle body section via a fit of the holding contour. Due to the attachment by means of the essentially annular projection, the sealing ring is secured in a simple manner and, on the one hand, can be removed from the cylinder head together with the injector during disassembly. On the other hand, the sealing ring cannot be lost when it is installed in the cylinder head, since it is fastened in the region of the nozzle body section by the projection. Thus, the injector and the sealing ring can be mounted together in a housing of the internal combustion engine and can be removed therefrom, so that the assembly or disassembly is considerably simplified.

The projection serving as a holder for the sealing ring only encloses a portion of the outer peripheral surface of the sealing ring. This ensures that the sealing ring protrudes over the projection in the direction of the longitudinal extent of the injector. For this purpose, a thickness dimension of the sealing ring is designed to be greater than a height of the projection, so that the sealing ring projects beyond the projection and a sealing surface is thus provided to the combustion chamber. In addition, the sealing ring is easily accessible from the outside on its section projecting beyond the projection and can therefore be removed quickly and easily from the holding contour during disassembly. This ensures a quick and easy exchange of the sealing ring on the injector.

Preferred embodiments of the invention are described in the further claims.

According to an advantageous embodiment of the invention, the nozzle body section is provided on a nozzle clamping nut or a nozzle body collar of the nozzle body. For a cheap fastening of the sealing ring, there are advantages if the projection is arranged on an end section of the nozzle clamping nut or the nozzle body collar, in particular a nozzle body shoulder of the nozzle body collar. The projection is formed, for example, in that a circular recess is formed along an end face of the nozzle clamping nut or the nozzle body shoulder facing the combustion chamber. The sealing ring can simply be pressed into this recess. In addition, the projection on the nozzle body section can be configured such that a sleeve is fastened on the nozzle clamping nut, for example shrunk onto the end section of the nozzle clamping nut, which protrudes beyond the end section and thereby forms the retaining contour for the sealing ring.

For a quick exchange of the sealing ring, it has proven to be advantageous to make at least one groove or an incision in the projection. A tool can be used to disassemble or change the sealing ring through the groove. The tool can be bar can be brought up to the outer circumferential surface of the sealing ring, so that the sealing ring can be easily removed from the holding contour with the tool and then replaced.

For a secure attachment of the sealing ring to the injector, it has proven to be advantageous in certain applications if the sealing ring is attached to the nozzle body section by means of at least one fastening element. Securing the sealing ring by means of the additional fastening element is particularly advantageous if there is play between the annular projection and the sealing ring inserted into the retaining contour. If there is play between the projection and the sealing ring, the fastening element ensures a secure connection of the sealing ring to the nozzle body section of the injector. A pin or notch pin, for example, can be used as the fastening element, by means of which the sealing ring is attached to the end face of the nozzle body section. Furthermore, the sealing ring can be connected to the front end section of the nozzle body section, for example by means of a bayonet catch.

In this context, it is advantageous to arrange at least one tab-shaped holding element on the outer circumferential surface of the sealing ring. For a connection between the sealing ring and the nozzle body section, the tab-shaped holding element is bent over and connected to the outer peripheral surface of the nozzle body section. This ensures that the sealing ring is securely attached to the outer peripheral surface of the nozzle body section.

In order to ensure that the sealing ring is easily and evenly pushed onto a nozzle body of the injector, it has proven to be advantageous if the sealing ring has at least one inner chamfer. Here, by upsetting the inner chamfer, which preferably has an axial securing of the sealing ring on the nozzle body achievable. Furthermore, it is preferred for fastening the sealing ring to the inner surface of the projection if the sealing ring has at least one outer ridge. Due to an excess of the external dimension, the sealing ring can be securely attached in the holding contour formed by the projection.

The invention is explained in more detail below on the basis of exemplary embodiments illustrated in the drawings. Show it:

Figure 1 is a partial sectional view of a first embodiment of the injector according to the invention. 2 shows a partial sectional view of a nozzle clamping nut of a second embodiment of the injector according to the invention; Fig. 3 is a partial sectional view of a third embodiment of the injector according to the invention.

1 shows a cross-sectional view of the injector according to the invention in the region of its nozzle body 4. The injector consists of an upper, cylindrical injector body, which is not shown in FIG. 1, and the lower nozzle body 4 arranged thereon.

As can be seen in FIG. 1, an outer diameter of the nozzle body 4 gradually decreases in the direction of a nozzle opening 6 which is arranged at one end of a nozzle body shaft 8 of the nozzle body 4. In the areas in which the outer diameter of the nozzle body 4 is reduced, an upper 10 and a lower 12 annular shoulder are formed on the outer circumference of a nozzle body section 2. Here, the nozzle body 4 is axially clamped against the injector body by means of a nozzle clamping nut 14 engaging the upper annular shoulder 10, so that the nozzle body 4 is held on the injector body via the nozzle clamping nut 14.

Furthermore, a nozzle needle 16 is provided, which is guided tightly with a nozzle needle guide 18 in the nozzle body 4.

The nozzle needle 16, which is guided axially in the nozzle body 4, can open or close the nozzle opening 6 in the injector by means of a lifting movement.

As further shown in FIG. 1, the injector is inserted into a stepped receiving bore 20 in a schematically illustrated cylinder head 22 of the internal combustion engine to be supplied with fuel. In this case, the area of the receiving bore 20 which has a reduced outer diameter opens into the combustion chamber of the internal combustion engine, so that it flows into the

A receiving bore 20 introduced nozzle body 8 and the nozzle opening 6 arranged at its free end fuel can be injected into the combustion chamber, not shown, of the internal combustion engine.

To seal the combustion chamber-side bore area of the receiving bore 20, a sealing ring 28 is arranged between an end portion 24 of the nozzle clamping nut 14 and a housing shoulder 26 formed on the cross-sectional transition of the receiving bore 20, which is guided on the nozzle body shaft 8 of the injector. The nozzle clamping nut 14 has, on its end section 24 facing the combustion chamber of the internal combustion engine, an integrally formed annular projection 30, which surrounds the sealing ring 28 on its outer circumferential surface 31 in regions and lies against a section of the outer circumferential surface 31. Here, the projection 30 is designed as a thin-walled, cylindrical extension of the nozzle clamping nut 14, which extends in the direction of the longitudinal extent of the injector. The projection 30 is sleeve-shaped and integrally formed on the nozzle clamping nut 14. Here, the nozzle clamping nut 14 comprises the nozzle body section 2, so that the projection in the region of the nozzle body section 2 OJ OJ t to H ¹ H ¹

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Contact surface for the sealing ring 28 is used. During assembly, the sealing ring 28 is inserted into the recess 36 such that the sealing ring 28 bears on a portion of its surface against the annular shoulder 40 and along a portion of its outer peripheral surface against the annular inner peripheral surface of the projection 30. Here, part of the sealing ring 28 projects beyond the projection 30, so that a sealing surface 42 is provided on the end section 24 of the nozzle clamping nut 14. The sealing ring 28 thus extends beyond the lower free end of the nozzle clamping nut 14.

3 shows a schematic cross-sectional view of a partial area of the injector according to the invention according to a third embodiment. This embodiment variant essentially corresponds to that according to FIG. 1, but has the difference that the annular projection 30 is arranged on a nozzle body collar 44 of the nozzle body section 2. In this case, the projection 30 is formed on an annular nozzle body shoulder 46 of the nozzle body collar 44. The sealing ring 28 is inserted into the holding contour formed by the projection 30 and pressed into the recess 36 formed on the nozzle body collar 44 by the nozzle body shoulder 46 and the inner circumferential surface of the projection 30. The sealing ring 28 is thus clamped onto the nozzle body collar 44 by means of a press fit and is held firmly and securely on the injector body 4 by the holding contour of the projection 30. The nozzle body 4 is connected to the injector body (not shown in FIG. 3).

As can be seen in FIGS. 1 and 2, the sealing ring 28 can be mounted in the region of the nozzle body section 2 of the injector both on the nozzle clamping nut 14 and directly on the nozzle body collar 44. The sealing ring 28 can be easily and securely preassembled on the injector by means of the projection 30 and can be replaced quickly and easily, for example in the event of wear. Here, the preassembled sealing ring 28 can be inserted into the receptacle simultaneously with the injector. bore 20 of the cylinder head 22 are used, which considerably simplifies the assembly.

Claims

claims

1. Injector for an internal combustion engine with a cylindrical injector body, a nozzle body (4) attached to the injector body and a sealing ring (28) which is arranged on a nozzle body section (2), characterized in that in a region of the nozzle body section (2 ) an essentially annular projection (30) is provided, which partially encloses an outer peripheral surface (31) of the sealing ring (28).

2. Injector according to claim 1, characterized in that the projection (30) on a nozzle clamping nut (14) or on a nozzle body collar (44) of the nozzle body section (2) is arranged.

3. Injector according to claim 1 or 2, characterized in that at least one groove (32) is provided in the projection (30).

4. Injector according to at least one of the preceding claims, characterized in that the sealing ring (28) is connected to the nozzle body section (2) by means of at least one fastening element.

5. Injector according to claim 4, characterized in that at least one tab-shaped holding element is provided on the outer peripheral surface of the sealing ring (28).

6. Injector according to at least one of the preceding claims, characterized in that the sealing ring (28) has at least one inner chamfer, one outer chamfer, one inner ridge and / or one outer ridge.