Title of Invention	INJECTION NOZZLE FOR INTERNAL COMBUSTION ENGINES
Abstract	An injection nozzle for internal combustion, engines with a blind hole having at least one spray hole and with a nozzle needle seat adjoining the blind hole, wherein the transition between nozzle needle seat and blind hole is rounded, characterized in that a nozzle needle in the region 'of the nozzle needle seat and the adjoining part of the blind hole is of truncated cone shape.

Full Text

Prior Art The invention is based on an injection nozzle for internal combustion engines with a blind hole having at least one spray hole and with a nozzle needle seat adjoining the blind hole. Blind hole fuel injection nozzles of the generic type have a large variation in the flow resistance, particularly in the partial lift range of the nozzle needle, and hence also in the injected fuel quantity. As a result the performance in terms of emissions and fuel consumption of many internal combustion engines fitted with these blind hole injection nozzles is less than optimal. The object of the invention is to provide a blind hole injection nozzle, in which the variation in the injected fuel quantity in the partial lift range of the nozzle needle in different examples of a blind hole injection nozzle of the same type is reduced, thereby improving the fuel consumption and emissions performance of internal combustion engines fitted with blind hole injection nozzles according to the invention. This object is achieved by an injection nozzle for internal combustion engines with a blind hole having at least one spray hole and with a nozzle needle seat adjoining the blind hole, in which the transition between nozzle needle seat and blind hole is rounded. Because, according to the invention, the transition between nozzle needle seat and blind hole is rounded and therefore has a defined geometry, the restrictive effect of the ecansition between nozzle needle seat and blind hole, which is of decisive importance in the partial lift range of the nozzle needle, is also defined and therefore varies only very slightly between different examples of an injection nozzle of the same type. This means that by measuring the operating performance of one blind hole injection nozzle according to the invention the operating performance of all other blind hole injection nozsles of the same type can be predicted with substantially greater accuracy and the variation in the injection sequence correspondingly optimised. In one embodiment of the invention the transition between valve nozzle seat and blind hole is rounded with a radius of between 0.01 mm and 0.1 mm, preferably between 0.04 mm and 0.06 mm, so that on the one hand the rounding already significantly reduces the variation in the partial load performance of the injection nozzles, and on the other the rounding can be produced at low cost. In a further embodiment of the invention the blind hole is tapered, so that the partial load performance of tapered blind hole injection nozzles is improved. Further to the invention, it is proposed that the blind hole be of cylindrical design, so that the partial load performance of cylindrical blind hole injection nozzles is also improved. In a variant of the injection nozzle according to the invention it is proposed that the nozzle needle seat be of truncated cone shape, thereby producing a good sealing effect and good centring of the nozzle needle in the nozzle needle seat. In another embodiment of the invention the taper angle of the nozzle needle seat is 60°, so that a good sealing effect is obtained between nozzle needle and nozzle needle seat. Further to the invention, the taper angle of the nozzle needle is up to one degree, preferably 15 - 30 angular minutes, larger than the taper angle of the nozzie neeaie seac, so cnat cne sealing surface is reduced and is shifted into the area of the greatest diameter of the"nozzle needle. In another embodiment the blind hole is a mini-blind hole or a micro-blind hole, so that the advantages according to the invention can also be utilised in these injection nozzles. In another embodiment the transition between spray hole and blind hole is rounded, so that the restrictive effect of the spray hole is reduced and varies within a narrower tolerance range. The object stated in the introductory part is also achieved by an injection nozzle for internal combustion engines with a blind hole having at least one spray hole, characterized in that the transition between spray hole and blind hole is rounded. This measure reduces the variation in the operating performance of injection nozzles. Further advantages and advantageous developments of the invention may be inferred from the following description, from the drawing and the claims. An example of an embodiment of the subject matter of the invention is represented in the drawing and is described in more detail below. In the drawing: Figure 1 shows a cross-section through a blind hole injection nozzle and Figure 2 shows a characteristic curve for the hydraulic diameter of the injection nozzle plotted over the valve needle lift. Figure 1 shows an injection nozzle 1 with a tapered blind hole 2. The blind hole 2 may also be cylindrical or it may be a mini-blind hole or a micro-blind hole 2. In the latter cases the volume of the blind hole 2 is reduced compared to the type represented in Figure 1. As a result less fuel evaporates into the combustion chamber when the internal combustion engine is switched off. The fuel (not shown) passes out of the blind hole 2 by way of a spray hole 3 into the combustion chamber (likewise not "shown) . A nozzle needle seat 4 of truncated cone shape adjoins the tapered blind hole 2. The nozzle needle seat 4 may have a taper angle of 60°. The blind hole 2 need not be tapered, it may also be cylindrical. A nozzle needle 5 lies on the nozzle needle seat 4. In Figure 1 it can clearly be seen that the taper angle of the nozzle needle 5 is larger than the taper angle of the nozzle needle seat 4. As a result the contact zone 6 between nozzle needle 5 and nozzle needle seat 4 lies in the area of the greatest diameter of the nozzle needle 5 and the surface pressure between the nozzle needle 5 and the nozzle needle seat 4 is increased. The difference in the cone angles of nozzle needle 5 and nozzle needle seat 4 is exaggerated in Figure 1. As a rule, the above-mentioned difference is less than 1 degree and varies with a range of a few angular minutes. A transition between blind hole 2 and nozzle needle seat 4 according to the prior art is represented as edge 7 on the left-hand side of Figure 1. The said edge 7 is produced when the nozzle needle seat 4 is being ground. The edge 7 may be a sharp burr or a smooth edge, depending on the method of machining. The flow resistance of the edge 7 is essentially influenced by its condition. A rounded transition 8 according to the invention between blind hole 2 and nozzle needle seat 4 is shown on the right-hand side of Figure 1. The rounding of the transition 8 may be circular in cross-section, for example, the radius being in the range from 0.01 mm to 0.1 mm, preferably 0.04 mm to 0.06 mm. The rounding according to the invention at any rate means that the geometry of the transition 8 between nozzle needle seat 4 and blind hole 2 in injection nozzles 1 of the same type only varies within a very narrow tolerance range; i.e. the geometry of the transition 8 is defined, and therefore the flow resistance of the transition 8 is also clearly defined, when the nozzle needle 5 is lifted from the* nozzle needle seat 4 in the direction of the nozzle needle lift 9. Consequently there is a large decrease in the variation in flow resistance of different examples of injection nozzles according to the invention in the area of the transition 8 between nozzle needle seat 4 and blind hole 2. The results of the variation in the flow resistance of injection nozzles 1 in the area of the transition 7 or 8 will be illustrated with reference to the diagram shown in Figure 2. In figure 2 the hydraulic diameter 10 of a blind hole injection nozzle 1 is qualitatively plotted over the nozzle needle lift 9. The hydraulic diameter 10 is a quantity by means of which any flow cross-sections can be compared with regard to their flow resistance. The flow resistance of a tube of circular cross-section serves as reference quantity. A cross-section with large hydraulic diameter has a low flow resistance and vice-versa. In figure 2 the nozzle needle lift 9 has been divided into two ranges. The first range extends from zero to "a", the second range, hereinafter referred to as the partial lift range, extends from "a" to "b". The full nozzle needle lift is reached at "c". When a closed injection nozzle 1, in which the nozzle needle 5 is resting on the nozzle needle seat 4, is opened, a very small nozzle needle lift 9 in the area of the contact zone 6 produces a very narrow gap, through which the fuel under pressure can flow into the blind hole 2. This very narrow gap decisively determines the flow resistance of the injection nozzle 1 and thereby also defines the hydraulic diameter 10. Since the flow resistance of this very narrow gap is large, the hydraulic diameter 10 of the injection nozzle 1 is very small for a very small nozzle needle lift 9. In the partial lift range between "a" and "b" the flow resistance of the injection nozzle 1 is decisively determined by t"he edge 7 or the transition 8 between nozzle needle seat 4 and blind hole 2. In the partial lift range, therefore, the edge 7 or the transition 8 is also of great significance for the hydraulic diameter of the injection nozzle 1. This means that changes in the geometry of the edge 7 or the transition 8 between nozzle needle seat 4 and blind hole 2 will result in changes in the hydraulic diameter 10. In the full nozzle needle lift range "c" the spray hole 3 of the injection nozzle 1 is decisive in determining the hydraulic diameter of the injection nozzle 1. Accordingly with this, variations in the geometry of the edge 7 or the transition 8 therefore lead to a change in the characteristic curve 11 for the injection nozzle 1, primarily in the partial lift range between "a" and "b". Figure 1 does not show the possibility of also rounding the transition between blind hole 2 and spray hole 3. This serves to reduce the flow resistance of the injection nozzle and prevents a burr being left, for example, when drilling the spray hole 3, which is as a rule done from the outside inwards. Such a burr can lead to an increase in the flow resistance of an injection nozzle 1, particularly at full nozzle needle lift. The resulting disadvantages correspond to those disadvantages, already stated and further described below, that are present in injection nozzles 1, in which the flow resistance of the edge 7 or the transition 8 varies markedly. The effects of various geometries of the transition 7 or 8 on the hydraulic diameter in the partial lift range are suggested by the characteristic curves 11, 12 and 13 in Figure 2. The dashed characteristic curve 12 represents a geometry of an edge 7 or a transition 8, which has a larger hydraulic diameter compared to the characteristic curve 11 and consequently has lower restriction losses. The dashed characteristic curve 13 shows the effects of a geometry of a transition 7 or 8, which has a greater restrictive action compared to the characteristic curve 11 in Figure 2. In the case of series-production internal combustion engines the characteristics map of the internal combustion engine and the associated fuel injection system is determined by measurements on the basis of one or more selected test specimens. The characteristics maps determined by such a method form the basis of all fuel injection systems of the same type. In the following, it is assumed that the characteristic curve 11 is a measured characteristic curve and that this characteristic curve 11 is stored in the control unit of the fuel injection system. It is furthermore assumed that two injection nozzles taken from series production have the characteristic curves 12 and 13. If the injection nozzles 1 having the characteristic curves 12 and 13 now interact with a control unit, in which the characteristic curve 11 is stored, the actual fuel injection quantity in the partial lift range will not correspond to the optimum fuel injection quantity according to the characteristic curve 11, measured on the test specimens, so that the power output and/or the emission performance of the internal combustion is impaired. Conversely it may be concluded that by rounding the transition 8 between valve needle seat 4 and blind hole 2, the variation in the characteristic curves 11, 12 and 13 is reduced. The conformity between the characteristic curve 11 stored in the control unit and the characteristic curves 11 and 12 of two injection nozzles taken from series production is thereby significantly improved. The conformity may be improved by a factor of 2 to 3, for example. As a result the actual injected fuel quantity corresponds exactly to the fuel injection quantity preset by the control unit and the fuel consumption and^emissions performance of the internal combustion engine is optimal. All features represented in the description, in the following claims and in the drawing may exist both separately and in any combination with one another essential for the invention. WE CLAIM: 1. An injection nozzle (1) for internal combustion engines with a blind hole (2) having at least one spray hole (3) and with a nozzle needle seat (4) adjoining the blind hole (2), wherein the transition (8) between nozzle needle seat (4) and blind hole (2) is rounded, characterized in that a nozzle needle (5) in the region of the nozzle needle seat (4) and the adjoining part of the blind hole (2) is of truncated cone shape. 2. The injection nozzle (1) according to Claim 1, wherein the transition (8) between nozzle needle seat (4) blind hole (2) is rounded with a radius between 0.01 mm and 0.1 mm, preferably between 0.04 mm and 0.06 mm. 3. The injection nozzle (1) according to Claim 1 or 2, wherein the blind hole (2) is tapered. 4. The injection nozzle (I) according to Claim 1 or 2, wherein the blind hole (2) is cylindrical. 5. The injection nozzle (1) according to any of the preceding Claims, wherein the nozzle needle seat (4) is of truncated cone shape. 6. The injection nozzle (1) according to Claim 5, wherein the taper angle of the nozzle needle seat (4) Is 60°. 7. The injection nozzle (1) according to either of Claims 5 or 6, wherein the taper angle of the nozzle needle (5) is up to one degree, preferably 15 to 30 angular minutes larger than the taper angle of the nozzle needle seat (4). 8. The injection nozzle (1) according to any of the precedmg Claims, wherein the blind hole (2) is a mini-blind hole or a micro-blind hole. 9. The injection nozzle (1) according to any of the preceding Claims, wherein the transition between spray hole (3) and blind hole (2) is rounded. 10. The injection nozzle (1) for internal combustion engines with a blind hole (2} having at least on spray hole (3), wherein the transition between spray hole (3) and blind hole (2) is rounded.

Documents:

in-pct-2001-0483-che abstract-duplicate.pdf

in-pct-2001-0483-che abstract.pdf

in-pct-2001-0483-che claims-duplicate.pdf

in-pct-2001-0483-che claims.pdf

in-pct-2001-0483-che correspondence-others.pdf

in-pct-2001-0483-che correspondence-po.pdf

in-pct-2001-0483-che description(complete)-duplicate.pdf

in-pct-2001-0483-che description(complete).pdf

in-pct-2001-0483-che drawings.pdf

in-pct-2001-0483-che form-1.pdf

in-pct-2001-0483-che form-19.pdf

in-pct-2001-0483-che form-26.pdf

in-pct-2001-0483-che form-3.pdf

in-pct-2001-0483-che form-5.pdf

in-pct-2001-0483-che others.pdf

in-pct-2001-0483-che petition.pdf