The invention relates to a fuel injection valve for internal combustion engines.
A fuel injection valve of this type is known from DE 10 2008 001 330 A1 by the applicant. Said fuel injection valve comprises essentially, on the side facing the combustion chamber of the internal combustion engine, a nozzle body which is accommodated in a housing and in which a nozzle needle is guided in such a way that it can move up and down. The nozzle needle is at least indirectly axially clamped, together with the nozzle body by means of a clamping nut, against a holding body arranged in the housing. The clamping nut has an inner thread as part of a threaded connection, which inner thread interacts with a corresponding external thread on the holding body and also forms, in particular, a seal of the housing for fuel which is arranged in the region of the nozzle body and which is under relatively high pressure; a pressure of more than 1500 bar is meant here; during operation of the fuel injection valve.
The trend in fuel injection technology is for increasingly high fuel injection pressures in order to achieve better efficiency levels and/or a lower consumption. As a result, increasingly stringent requirements are made for the seal of the housing, in the present case in particular in the region of the threaded connection.
Taking the illustrated prior art as a starting point, the invention is based on the object of developing a fuel injection valve for internal combustion engines in such a way that the threaded connection thereof connects the clamping nut to the holding nut and forms a seal of the housing toward the outside, in such a way that said seal is particularly tight, in particular in the case of relatively high fuel pressures.
This object is achieved in a fuel injection valve for internal combustion engines wherein the threaded connection (20) comprises at least two toothing regions (21, 22) which have different threaded dimensions and are arranged axially one behind the other in the longitudinal direction of the housing. The invention is based here on the idea of developing the threaded connection in such a way that there are at least two toothing regions which have different threaded dimensions and adjoin one another axially one behind the other in the longitudinal direction of the housing. This makes it possible to optimize the respective toothing regions with respect to their specific properties and/or functions. In particular this permits, for example, a first toothing region to be embodied in an optimum way in terms of its seal, while a second toothing region is optimized in terms of the relatively simple mounting of the clamping nut.
In a structurally preferred embodiment it is proposed that a thread-free intermediate section is formed between the two toothing regions. This thread-free intermediate section permits, in particular, the two toothing regions on the clamping nut and respectively on the holding body to be implemented relatively easily in terms of fabrication technology.
An embodiment in which the threaded dimensions of the two toothing regions differ in the thread diameters and the number of teeth, and in that the lead of the toothing regions are equal, is particularly preferred. Embodying the threaded dimensions in such a different way both provides the desired seal while at the same time permitting easy mounting of the clamping nut on the holding body.
In a particularly preferred structural embodiment it is proposed that the axial length of the thread-free intermediate region corresponds to the axial length of a first toothing region on the clamping nut, which toothing region is arranged on the side of the clamping nut facing the holding body. Such an embodiment always permits the clamping nut to be guided and/or to engage on the holding body in the axial direction when the clamping nut is screwed onto the holding body.
In order to achieve the desired improved seal of the threaded connection, it is proposed that the second toothing region has, on the side of the clamping nut facing the nozzle body, the smaller thread diameter and twice the number of teeth compared to the first toothing region. As a result, according to a further refinement of the invention, it is made particularly easily possible for the wall thickness of the clamping nut to be larger in the second toothing region than in the first toothing region. In this context, the increased wall thickness of the clamping nut can particularly well absorb the pressure stresses which occur, and widening of the clamping nut compared to the prior art owing to the hydraulic pressure is reduced, which improves the seal of the second toothing region.
Further advantages, features and details of the invention emerge from the following description of preferred exemplary embodiments and on the basis of the drawing, in which:
The fuel injection valve 100 has a housing 10, of which only certain areas are illustrated and in which, inter alia, an injection valve element (not illustrated), in particular in the form of a nozzle needle, is arranged in such a way that it can move up and down. Arranged within the housing 10 is a nozzle body 11 which simultaneously forms the end of the fuel injection valve 100 facing the combustion chamber of the internal combustion engine. The nozzle body 11 has, on its outer circumference, a step 12. In the illustration in
With respect to the rest of the design of a fuel injection valve 100 and the method of functioning thereof, reference is made to DE 10 2008 001 330 A1 by the applicant, which document is to be considered in this respect to be a component of this application.
In the region of the detail X in
While the first toothing region 21 in the region of the clamping nut 18 is arranged at the end of the clamping nut 18 facing away from the nozzle body 11, the second toothing region 22 is located in the region of the holding body 15, on the side facing the valve plate 14 near to the lower end face 26 of the holding body 15.
The first toothing region 21, which is embodied as an external thread on the holding body 15, has a thread with the dimensions M17×0.75 mm, while the second toothing region 22 on the holding body 15 is embodied as an external thread with the dimensions of M16×0.75 mm. Furthermore, the first toothing region 21, which is embodied as an internal thread, on the clamping nut 18 has half the number of teeth of the second toothing region 22 on the clamping nut 18.
As is apparent, in particular, from
The combination of
The threaded connection 20 which is described in this fashion on the fuel injection valve 100 can be modified in a variety of ways without departing from the inventive idea.
Number | Date | Country | Kind |
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10 2011 076 957 | Jun 2011 | DE | national |
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Jayendran, A., “Englisch für Maschinenbauer: Lehr- und Arbeitsbuch,” Springer DE, 2007, pp. 72-73. |
Number | Date | Country | |
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20120305823 A1 | Dec 2012 | US |