Patent ID: 12253056

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS

FIG.1shows a cross-section through a fuel injector10for an internal combustion engine according to the invention. The fuel injector10can be both a fuel injector for liquid fuel and also a fuel injector for gaseous fuel.

The fuel injector10is designed to supply fuel to a cylinder of the internal combustion engine, namely either directly into a combustion chamber of the cylinder or into a pre-chamber of the cylinder interacting with the combustion chamber or into a pipe of the internal combustion engine leading into the combustion chamber of the cylinder, which also carries combustion air to the cylinder.

The fuel injector10comprises a casing11. By way of the casing11, the fuel injector10can be mounted to the internal combustion engine, for example in the region of a cylinder head or a cylinder head cover.

Furthermore, the fuel injector10comprises a valve stem12, which carries a valve body13. The valve stem12can be directly actuated magnetically. The valve body13interacts with a valve seat14. In particular when the valve body13lies against the valve seat14, the fuel injector10does not allow any fuel flow. By contrast, when the valve body13is lifted off from the valve seat14, the fuel injector opens a fuel flow.

Furthermore, the fuel injector10comprises a guide and seat body15with a guide portion15afor the valve stem12and a seat portion15bproviding the valve seat14. Relative to the casing11, this guide and seat body15is embodied as separate, one-piece or monolithic assembly and mounted to the casing11.

As already explained, the guide portion15aof the guide and seat body15guides the valve stem12, wherein for this purpose the valve stem12penetrates a recess16in the guide portion15a. The seat portion15bof the guide and seat body15provides the valve seat14for the valve body13.

The guide portion15aof the guide and seat body15can be flowed about by fuel. The seat portion15bof the guide and seat body15by contrast can be flowed through by the fuel. Accordingly, when the valve body13is lifted off from the valve seat14and the fuel injector10opens a fuel flow, the fuel flows about the guide portion15aand flows through the seat portion15bof the guide and seat body15.

Between the guide portion15aand the seat portion15b, an intermediate portion15cof the guide and seat body is formed. In this intermediate portion15c, at least one recess17is introduced, which can be flowed through by fuel, so that the fuel, with opened fuel injector10, originating from the flowed-about guide portion15b, can overflow into the flowed-through seat portion15b.

The recesses17in the intermediate portion15cof the guide and seat body15accordingly serve for conducting the fuel, originating from the guide portion15a, in the direction of the seat portion15bwith opened fuel injector10.

The guide and seat body15projects with its guide portion15ainto the casing11. Between the casing11and the guide portion15aan annular space18is formed, which with opened fuel injector10is flowed through by fuel, wherein this fuel flowing through the annular space18flows about the guide portion15aon the outside.

Further, the intermediate portion15cof the guide and seat body15also projects in the casing11in the shown exemplary embodiment, at least partially. By contrast, the seat portion15bprojects out of the casing11of the fuel injector10, namely inFIG.1in such a manner that the valve seat14is positioned outside the casing11.

The valve stem12does not only penetrate the guide portion15a, but also the seat portion15bof the guide and seat body15, wherein between the valve stem12and the seat portion15ban annular space19is formed, which with opened fuel injector10is flowed through by fuel. The fuel flowing through the annular space19likewise flows through the seat portion15band, partially, flows about the valve stem12, namely that portion of the valve stem12which extends within the seat portion15bof the guide and seat body15.

The annular spaces18and19are coupled via the recesses17.

It is provided, in particular, that the flow cross-sections for the fuel gradually decrease in the direction of the valve seat14. Accordingly, the flow cross-section for the fuel is defined in the region of the guide portion15aby an outer diameter of the guide portion15aand an inner diameter of the casing11. The flow cross-section in the region of the recesses17of the intermediate portion15cof the guide and seat body15is defined by the diameter and the number of the recesses17. The flow cross-section in the region of the seat portion15is defined by the inner diameter of the seat portion15and an outer diameter of the valve stem12. In particular when the flow cross-sections in the flow direction of the fuel gradually decrease, pressure losses can be reduced.

InFIG.1, the fuel injector10, furthermore, comprises a union nut20. The union nut20comprises an internal thread21which interacts with an external thread22of the casing11. For fastening the guide and seat body15to the casing11, the union nut20clamps a projection15dof the guide and seat body15directed radially to the outside, which is formed between the intermediate portion15cand the seat portion15b, between the casing11and the union nut20. By way of this clamping, a sealing function between the guide and seat body15and the casing11can be provided.

Casing11and guide and seat body15are preferentially produced from a metallic material, wherein inFIG.1the guide and seat body15is then clamped relative to the casing11in a metallically sealing manner.

The circumferential projection15dof the guide and seat body15furthermore limits the introduction depth of the guide and seat body15into the casing11.

FIG.2shows the fuel injector10that additionally comprises a jet-cap23. The jet-cap23surrounds the seat portion15bof the guide and seat body15radially on the outside at least partially and projects over the valve seat14. By way of such a jet-cap23, the fuel jet flowing via the valve seat14can be shaped and specifically influenced.

According toFIG.2, a circumferential collar23aof the jet-cap23, just as the guide and seat body15, is likewise clamped with the help of the union nut20between the union nut20and casing11. The circumferential collar23aof the jet-cap23is positioned between the circumferential projection15dof the guide and seat body15and the union nut20, namely seen in the movement direction of the valve stem12.

Here it is pointed out that the valve body13and the valve stem12, during the opening of the fuel injector10, i.e. during the lifting-off of the valve body13from the valve seat14, opens towards the outside, i.e. is moved away from the casing11. Accordingly, the fuel injector10is a fuel injector with a valve body13opening towards the outside.

FIG.3shows the fuel injector10, in which the guide and seat body15is screwed to the casing11. Accordingly, the guide and seat body15comprises an external thread24, which interacts with an internal thread25of the casing11. By way of the screw-in depth of the guide and seat body15into the casing11, a stroke of the valve stem12can be adjusted.

InFIG.3, the sealing of the guide and seat body15relative to the casing11is effected via sealing element26formed as O-ring. The same is arranged in a groove of the guide and seat body15.

The fuel injector10according to one aspect of the invention allows, with little installation space requirement, in particular with small outer diameter in particular in a region below or, seen in the flow direction of the fuel, downstream of the guide portion15a, providing a large flow cross-section for the fuel. Central assembly of the fuel injector10is the guide and seat body15, which comprises the guide portion15aflowed about by fuel and the seat portion15bflowed through by the fuel. By way of the recesses17in the intermediate portion15c, the fuel, originating from the guide portion15a, can overflow into the region of the seat portion15b. The sealing of the guide and seat body15relative to the casing11, can take place by a clamping and/or a sealing element26configured as O-ring.

InFIG.3, a stroke adjustment for the stroke of the valve stem12is possible. While inFIGS.1and2the guide and seat body15is clamped to the casing11, the guide and seat body15inFIG.3is screwed to the casing11. Further, it is alternatively possible to connect the guide and seat body15to the casing11by welding.

The fuel injector10according to one aspect of the invention has a simple structure and can be cost-effectively produced. With little installation space requirement, it provides a large flow cross-section for the fuel. Preferentially, the fuel injector10is a fuel injector for gaseous fuel.

Thus, while there have shown and described and pointed out fundamental novel features of the invention as applied to a preferred embodiment thereof, it will be understood that various omissions and substitutions and changes in the form and details of the devices illustrated, and in their operation, may be made by those skilled in the art without departing from the spirit of the invention. For example, it is expressly intended that all combinations of those elements and/or method steps which perform substantially the same function in substantially the same way to achieve the same results are within the scope of the invention. Moreover, it should be recognized that structures and/or elements and/or method steps shown and/or described in connection with any disclosed form or embodiment of the invention may be incorporated in any other disclosed or described or suggested form or embodiment as a general matter of design choice. It is the intention, therefore, to be limited only as indicated by the scope of the claims appended hereto.