EP2757247A1 - Injection nozzle for a combustion engine - Google Patents

Abstract

The injection nozzle has an inner contour with a pre-chamber (14) that opens at an end into a spray chamber with an inlet opening (13). A cylindrical guide channel (17) that is connected to another end of the pre-chamber communicates with outside of a body through an outlet opening (18). The diameter or cross-section of the inlet opening of the pre-chamber is 50 percent larger than the guide channel. The pre-chamber comprises a constriction (16) with a narrowing section (15). The ratio of length of the guide channel to length of the pre-chamber lies in a range of 1 is to 0.2 to 1 is to 0.8.

Description

The invention relates to an injection nozzle, in particular hole nozzle, for an internal combustion engine. The invention also relates, in particular, to the injection-hole shape of such an injection nozzle.

Injectors are liquid, gas or powdered (powdered) substances, especially fuels, under (high) pressure from an injection pump or a pressure line system (common rail system) so in the combustion chamber of an internal combustion engine, e.g. air-compressing, self-igniting internal combustion engines such as diesel engines, inject that the combustion engine in each operating state as possible the best efficiency (ecological and economical) achieved. The mixture formation of the fuel in the combustion chamber and thus also the combustion process are decisively influenced by the internal shape of the injection holes of the injection nozzle.

There are different types of injectors, of which the so-called hole nozzle should be considered here. The perforated nozzle is used in internal combustion engines with direct injection, since with it a particularly fine distribution of the fuel is achieved. Hole nozzles are designed as a single-hole and multi-hole nozzles. One-hole nozzles have a spray hole, which is arranged in the direction of the nozzle axis or laterally thereof. Multi-hole nozzles can, for example, have up to 14 injection holes, which are usually arranged symmetrically to each other. One-hole and multi-hole nozzles are formed on one or more levels (spray hole geometry of the nozzle). Hole diameter or hole cross-section and hole length affect the shape and penetration depth of the spray jet and its spray pattern. The hole diameters are based on the design of the combustion chamber.

Over the last two decades, new injection systems for gas, diesel, heavy oil and biomass combustion engines have been developed through systematic research into environmental friendly (EURO, Tier, IMO) standards and optimal combustion of fuels. The result is common rail systems with their associated electronic total monitoring units. With regard to ecology and economy, an increase in efficiency can be observed with good coordination of all components.

An embodiment of the inner contours of one or more injection ports of a fuel valve (nozzle) can significantly influence the injection process in the combustion chamber of compression-ignition internal combustion engines. As an example for illustration DE 39 34 587 C2 called, which describes a method for producing by means of laser beams, high-precision through-holes in workpieces, in particular in injection nozzles, with bottle neck-like spray holes.

The document EP 2 365 207 A1 describes an injection nozzle for an internal combustion engine. The injection nozzle comprises at least one injection hole with a substantially bottle neck-like inner contour.

The object of the present invention is to provide an improved injection nozzle.

The object is achieved by an injection nozzle having the features of claim 1.

The object is also achieved by a spray-hole mold with the features of claim 15.

Accordingly, an injection nozzle, in particular a hole nozzle for an internal combustion engine, comprises a body in which a nozzle needle is displaceable is guided; a pressure chamber communicating with an inlet bore and a passage with a spray chamber, the passage having a needle seat for cooperation with a needle tip of the nozzle needle; and at least one spray hole through which the spray chamber communicates with the outside of the body. The at least one injection hole comprises a substantially bottle-like inner contour with at least one pre-chamber, which opens into the injection chamber with one end with an inlet opening; and a guide channel, which is connected to the other end of the at least one antechamber and communicates via an outlet opening with the outside (tip) of the body. The at least one antechamber has at least in the inlet opening a diameter or cross section which is at least 50% larger than the diameter or cross section of the guide channel, wherein the at least one prechamber has at least one constriction with at least one constriction section. A ratio of a length of the guide channel to a length of the pre-chamber is in a range of 1: 0.2 to 1: 0.8.

Comparative studies, calculations and simulations have shown that a special geometry of the inner contour of spray holes brings particular advantages. The injection hole of the injection nozzle is provided with a substantially bottle-like inner contour. Such a spray hole is also referred to as a bottleneck injection hole or "bottleneck spray hole".

In this case, the coaxial and sequential arrangement of functional areas of the spray hole allows optimal adaptation to the requirements of an associated combustion chamber of an internal combustion engine, e.g. in the fuel-air mixture formation. Favor is that the ratio of the length of the guide channel to the length of the prechamber in a range of 1: 0.2 to 1: 0.8.

This results in the advantage that compared to today's injection systems, such as common rail systems, the injection pressure can be significantly reduced with better ecological and economic effect, resulting in a lower power consumption of the injection system and a longer life of all affected components.

Another advantage is that over the prior art, a longer life of high-pressure pumps, pump elements, injectors, Nozzles and the entire injection system due to lower pressure stress results.

• zumindest eine Vorkammer, die mit einem Ende mit einer Einlassöffnung in die Spritzkammer mündet; und einen Führungskanal, der mit dem anderen Ende der zumindest einen Vorkammer verbunden ist und über eine Austrittsöffnung mit der Außenseite des Körpers kommuniziert.

It is advantageous that the substantially bottle-like inner contour comprises:

• at least one pre-chamber, which opens at one end with an inlet opening into the injection chamber; and a guide channel, which is connected to the other end of the at least one antechamber and communicates via an outlet opening with the outside of the body.

• Einlass eines Spritzmediums in die Vorkammer
• Aufnahme des Spritzmediums in der Vorkammer
• Verengungsfunktion im Trichterbereich
• Führungsfunktion im Führungskanal
• Austritt des Mediums an der Außenseite des Düsenkörpers (Einmündung in den Verbrennungsraum)

The essentially bottle-like inner contour of the bottleneck spray hole or Bottleneck Spray Hole has the following functions:

• Inlet of a spray medium in the antechamber
• Recording of the spray medium in the prechamber
• Narrowing function in the funnel area
• Guide function in the guide channel
• Outlet of the medium on the outside of the nozzle body (opening into the combustion chamber)

Furthermore, it is advantageous that the inlet opening of the at least one pre-chamber is formed with rounded inlet edges, whereby less flow losses occur and the long-term behavior of the injection nozzle is improved. In this case, the rounded inlet edges of the inlet opening can be formed with the same rounding radii, which can offer a manufacturing advantage.

The guide channel may be cylindrical, frusto-conical or formed in a combination of these forms, whereby the flow is further influenced. In this case, a diameter or cross section of the at least one antechamber, at least in the region of the inlet opening, is at least 50% greater than a diameter or cross section of the guide channel. This can be in the antechamber form a constriction, which has at least one constriction section. With the help of this constriction section and the associated influenceable gradual and / or abrupt change in diameter or change in cross section, the type of flow of the medium flowing through can be influenced. Thus, a laminar or turbulent or transitional flow type can be adjusted.

In one embodiment, the at least one pre-chamber extends in a circular cylindrical configuration up to the at least one constriction with the at least one constriction section. Alternatively or in combination, e.g. in sections, the at least one pre-chamber may be frusto-conical in the direction of the guide channel.

The outlet opening of the guide channel can be formed sharp-edged, whereby the spray pattern of the exiting injection jet can be adjusted. It is advantageous if a formed by an outer surface of the body and an inner wall or the central axis of the guide channel exit angle of the outlet opening of the guide channel is preferably less than 90 °. In this case, the outlet angle of the outlet opening of the guide channel may be frusto-conical.

The at least one spray hole may comprise in its overall length a plurality of functional regions (A - E), which are arranged sequentially one behind the other and rotationally symmetrical on the same axis. Due to their division, these functional areas can each be configured individually individually so that the injection jet is optimally provided for the internal combustion engine to be assigned. This mechanical-hydraulic optimization of the functional areas can be superimposed with the aid of an electronic engine control unit (EECU) additional, optimal boundary conditions and parameter settings or states.

Of the functional areas, a first functional area (A) may comprise the inlet opening, a second functional area (B) the at least one antechamber, a third functional area (C) the at least one constriction, a fourth functional area (D) the guide channel and a fifth functional area (E) include the outlet opening.

It is also possible that the same functional areas are arranged several times in succession, such as two second functional areas with two prechambers and two constrictions. This can be done a graduated pressure build-up in the antechambers. It is also conceivable that, instead of a pressure build-up, an intermediate stage with pressure reduction, e.g. can be provided with an extension.

The bottleneck-shaped function package (AE) can be introduced in modulated drilling operations from outside to inside the injection hole of the injection nozzle become. Different processing methods are possible, such as lasers.

Alternatively, the bottle-neck-shaped function package (A-E) can also be combined in a structural unit and be pressed into a cylindrical injection hole. This can facilitate manufacturing processes, especially since the processing of the injection hole for creating the inner contour can be made at a different location.

The substantially bottle-like inner contour of the injection hole is furthermore dependent on at least the inner shape, the volume, the air circulation and the combustion pressure of an associated combustion chamber of the internal combustion engine.

A spray-hole mold, which has a substantially bottle-shaped inner contour, of a spray hole of an injection nozzle can be realized according to the embodiments described above.

The injection nozzle according to the invention can be used both for use for the injection of fuels in powdered, liquid or gaseous form in the combustion chamber of combustion units, such as internal combustion engines, as well as for use for the atomization of powdery, liquid or gaseous media.

In addition, advantageous adaptations to the most diverse requirements of internal combustion engines in the combustion chamber with regard to the injection jet can also be made by the fact that the bore length ratios of the individual functional areas can be adapted changed.

Thus, it is possible with the embodiments described above, to align the injection hole with its inner contour or the injection hole inner mold or injection hole shape specifically on the design of a respective associated combustion chamber. This results in a large number of variants of ratios of the functional areas, eg lengths, widths, diameters, cross sections as a function of injection pressures. With the help of appropriate simulation methods, the respective geometric conditions for the respective application can be adapted and optimized, so that in each case Optimal conditions regarding combustion, fuel consumption and life of the components result.

Fig. 1

eine schematische Teilschnittdarstellung einer erfindungsgemäßen Einspritzdüse als Lochdüse in geschlossener Stellung;

Fig. 2

eine schematische Teilschnittdarstellung der Einspritzdüse nach Fig. 1 in geöffneter Stellung;

Fig. 3

eine schematische Schnittdarstellung eines Spritzlochs der erfindungsgemäßen Einspritzdüse;

Fig. 4

eine vergrößerte Darstellung einer Einlassöffnung der erfindungsgemäßen Einspritzdüse nach Fig. 3; und

Fig. 5

eine vergrößerte Darstellung einer Vorkammer mit Verengung der erfindungsgemäßen Einspritzdüse nach Fig. 3.

The invention will now be explained in more detail by means of embodiments with reference to the accompanying drawings. Hereby show:

Fig. 1

a schematic partial sectional view of an injection nozzle according to the invention as a hole nozzle in the closed position;

Fig. 2

a schematic partial sectional view of the injection nozzle according to Fig. 1 in open position;

Fig. 3

a schematic sectional view of a spray hole of the injection nozzle according to the invention;

Fig. 4

an enlarged view of an inlet opening of the injection nozzle according to the invention Fig. 3 ; and

Fig. 5

an enlarged view of an antechamber with constriction of the injection nozzle according to the invention Fig. 3 ,

Identical components or functional units with the same function have the same reference numerals in the figures.

Fig. 1 shows a schematic partial sectional view of an injection nozzle 1 according to the invention as a hole nozzle in the closed position. Fig. 2 shows this injector 1 in the open position.

In the Figures 1 and 2 only the lower region of a body 2 of the injection nozzle 1 is shown with a nozzle tip 3 (highlighted by a circle). The body 2 has in the upper part of the injection nozzle 1 has a circular cross section in which in the longitudinal direction of the body 2, a nozzle needle 7 is longitudinally movable in a bore 7 '. The bore 7 'merges into a pressure chamber 5 formed in the body 2. Laterally parallel to the bore 7 ', an inlet bore 4 in the body 2 is arranged. The inlet bore 4 opens at its lower end into the pressure chamber 5, which narrows down to a passage 9. The passage 9 has a conical needle seat 9 'and finally opens into a spray chamber 6, which is arranged in the nozzle tip 3 of the injection nozzle 1 with a rounded bottom. The body 2 of the injection nozzle 1 is formed here as a nozzle tip 3 hemispherical and has a smaller wall thickness 3 'than above. Through this wall thickness 3 'of the nozzle tip 3 extend in this example, two injection holes 10, which open through an inner injection chamber wall 11 through an inlet opening 13 in the rounded bottom of the injection chamber 6 and through an outlet opening 18 in an outer surface 20 of the nozzle tip 3 ,

The nozzle needle 7 extends from the bore 7 'through the pressure chamber 5 into the passage 9 into the injection chamber 6. In this case, the nozzle needle 7 tapers to a conical needle tip 8, which cooperates with the conical needle seat 9 'of the passage 9 as a tight valve seat.

The nozzle needle 7 is longitudinally adjustable by means of a drive, not shown, for example, mechanically, electromagnetically or by increasing pressure of fuel in the pressure chamber 5. To open the needle seat 9 ', the nozzle needle 7 is moved by this drive upwards. This open position of the injection nozzle 1 is in Fig. 2 illustrated. The conical needle tip 8 has the needle seat 9 'released. Fuel, which is under pressure in the pressure chamber 5 and also replenished under pressure through the inlet bore 4, now flows from the pressure chamber 5 through the passage 9 into the injection chamber 6 and from there through the injection holes 10 each as an injection jet 21 to the outside the combustion chamber of an internal combustion engine, not shown.

The respective injection jet 21 is influenced, inter alia, by the geometry of the respective injection hole 10 with regard to its spray pattern. Its speed, type of flow, pressure and pressure propagation continue to play a decisive role.

Fig. 3 FIG. 2 shows a schematic sectional view of a spray hole of the injection nozzle 1 according to the invention. FIG.

The injection hole 10 in Fig. 3 Due to its shape it is also called a bottleneck injection hole or bottleneck spray hole. Such injection holes 10 are formed in a variety of bodies 2 of injectors 1 in the nozzle tip 3 made of hardened special steels (eg DUALOY). The nozzle needle 7 is made of a special steel or ceramic materials.

Starting from the inlet opening 13, which is introduced into the injection chamber wall 11 of the injection chamber 6, the injection hole 10 initially extends in an antechamber 14, for example in a circular cylindrical design, and then enters a constriction 15 with a constriction portion 16 as a bottle in a Bottom neck, a guide channel 17 via. A diameter or cross section of the pre-chamber 14 is at least 50% larger than a diameter or cross section of the guide channel 17. The end of the guide channel 17 opens into the outlet opening 18 in the outer surface 20 of the nozzle tip 3. The injection hole 10 has substantially over the entire longitudinal section a rotationally symmetrical bottle shape.

The injection hole 10 has functional areas A to E, which are indicated in part by circles, reference numerals and horizontal lines and have different functions.

The circle at the inlet opening 13 denotes the first functional area A with fuel inlet. Fig. 4 shows an enlarged view of the inlet opening 13 of the injection nozzle 1 according to the invention Fig. 3 , Here an inlet edge 12 of the inlet opening 13 is rounded. The hatched areas indicate contours of the injection chamber wall 11 in the injection chamber 6 in the region of the inlet opening 13. This is just one of several possible variants indicated.

In the following functional area B with the dashed circle the prechamber 14 is indicated. This will be in Fig. 5 illustrates which an enlarged view of the antechamber 14 with constriction 15 of the injection nozzle 1 according to the invention Fig. 3 shows. In this case, a diameter or cross section of the pre-chamber 14 is at least in the region of the inlet opening 13 by at least 50% greater than a diameter or cross section of the guide channel 17th

Between the horizontal lines is the functional area C of the constriction 15, to which the functional area D of the guide channel 17 adjoins.

Finally, a last functional area E with the outlet opening 18 is present.

In the functional area B of the prechamber 14, when the needle seat 9 'is opened (see FIG Fig. 2 ) Built on the constriction 15 with the funnel-shaped constriction section 16 to the subsequent guide channel 17, a pressure in the flowing from the inlet port 13 to the outlet port 18 fuel, wherein a predosing takes place. This flow rate of the fuel is subject to only a slight contraction in the pressure propagation in the pre-chamber 14 and leads to a timely injection over all injection holes 10 of the injection nozzle 1 (see Fig. 1 and 2 ). Compared to current common rail systems, the injection pressure can be significantly reduced with better environmental and economic effect, resulting in lower power consumption of the system and lower pressure stress of the components involved to a longer life of high pressure pumps, pump elements, injectors, nozzles and the entire injection system leads.

The functional area C of the constriction 15 with the funnel-shaped constriction section 16 is formed as a kind of control cam, which in Fig. 5 is indicated by contour variants with hatched areas. Two such possible contour variants are here indicated by a frustoconical design and a circular cylindrical design (without hatched area) of the antechamber 14. Depending on the design, this control curve influences the flow type of the fuel flowing through such that the flow type varies, for example, is laminar or turbulent. In this phase, the flow rate of the fuel or an injection medium increases significantly. The negative effect of lower system pressures is compensated by the design and operation of the funnel-shaped constriction section 16.

In the following phase of this compression process phase or in the subsequent functional area D of the guide channel 17 of the fuel flowing through is fuel jet and bundled so that it in a coordinated form (eg bushy, stretched, etc.) designed by the designer of the internal combustion engine combustion chamber for Can be made available.

In the last functional area E with the outlet opening 18, the bore of the guide channel 17 is provided at the outlet opening 18 with a sharp-edged jet tear-off edge 19, wherein an exit angle 22, by the Outside surface 20 and the outer wall of the nozzle tip 3 and the inner wall or the central axis of the guide channel 17 is formed, if possible, is less than 90 °.

The dimensioning of such injection holes 10 as bottleneck injection holes or bottleneck spray holes with respect to different diameters or cross sections, length of the individual functional areas, configuration of the funnel shape in the constriction section 16 and dimensional ratios of the individual functional areas to each other can be optimized, for example via a simulation model. In this simulation model, the flow conditions of different injection media can also be simulated. The basis of calculation is the combustion chamber (in form and volume) provided by the designer of the internal combustion engine, the fuel (in composition, viscosity, density) and the weighting of the objective (more economy or more ecology). A form optimization takes place in each case by iteration experiments.

In one embodiment, so is the ratio of a length of the guide channel 17 (here between the throat portion 16 and the outlet opening 18 - see Fig. 3 ) and a length of the pre-chamber 14 (here between the inlet opening 13 and the narrowing section 16 - see also Fig. 3 ) in a range of 1: 0.2 to 1: 0.8.

In the embodiments described above, the injection hole shape or inner contour of the injection hole 10 is aligned in each case correspondingly to the configuration of an associated combustion chamber. For this purpose, the factors internal shape of the combustion chamber, volumes, air circulation and combustion pressure also play a decisive role for the design of the injection hole 10

The embodiment described above does not limit the invention. It is modifiable within the scope of the appended claims.

Thus, the injection hole 10 may have more than one pre-chamber 14, wherein a plurality of second functional areas B are present. It is also possible for a plurality of narrowing sections 16 and thus a plurality of functional areas C to be possible.

LIST OF REFERENCE NUMBERS

1

injection

2

body

3

injector cap

3 '

Wall thickness nozzle tip

4

inlet bore

5

pressure chamber

6

injection chamber

7

nozzle needle

7 '

drilling

8th

pinpoint

9

passage

9 '

needle seat

10

spiracle

11

Spray chamber wall

12

inlet edge

13

inlet port

14

antechamber

15

narrowing

16

throat portion

17

guide channel

18

outlet opening

19

Beam separation edge

20

outer surface

21

Injection jet

22

exit angle

A ... E

functional area

Claims (15)

Injection nozzle (1), in particular hole nozzle for an internal combustion engine, with: a. a body (2) in which a nozzle needle (7) is slidably guided; b. a pressure chamber (5) which communicates with an inlet bore (4) and via a passage (9) with a spray chamber (6), wherein the passage (9) has a needle seat (9 ') for cooperation with a needle tip (8) of the nozzle needle (7); and c. at least one injection hole (10), via which the injection chamber (6) communicates with the outside of the body (2), d. wherein the at least one injection hole (10) has a substantially bottle-like inner contour
at least one pre-chamber (14) which opens at one end with an inlet opening (13) in the injection chamber (6); and
a cylindrical guide channel (17) which is connected to the other end of the at least one pre-chamber (14) and communicates via an outlet opening (18) with the outside (tip) of the body (2), e. the at least one prechamber (14) has a diameter or cross section at least in the inlet opening (13) that is at least 50% larger than the diameter or cross section of the guide channel (17), f. wherein the at least one prechamber (14) has at least one constriction (15) with at least one constriction section (16),
characterized in that G. a ratio of a length of the guide channel (17) to a length of the prechamber (14) is in a range of 1: 0.2 to 1: 0.8. Injection nozzle (1) according to claim 1, characterized in that the inlet opening (13) of the at least one pre-chamber (14) is formed with rounded inlet edges (12). Injection nozzle (1) according to claim 2, characterized in that the rounded inlet edges (12) of the inlet opening (13) of the at least one antechamber (14) are formed with the same rounding radii (12). Injection nozzle (1) according to one of claims 1 to 3, characterized in that the at least one pre-chamber (14) extends in a circular cylindrical configuration up to the at least one constriction (15) with the at least one constriction section (16). Injection nozzle (1) according to one of claims 1 to 3, characterized in that the at least one antechamber (14) is frusto-conical in the direction of the guide channel (17). Injection nozzle (1) according to one of claims 1 to 5, characterized in that the outlet opening (18) of the guide channel (17) is formed sharp-edged. Injection nozzle (1) according to one of claims 1 to 6, characterized in that an outlet angle (22) formed by an outer surface (20) of the body (2) and an inner wall or the central axis of the guide channel (17) of the outlet opening (18) of Guide channel (17) is less than 90 °. Injection nozzle (1) according to claim 7, characterized in that the outlet angle (22) of the outlet opening (18) of the guide channel (17) is frusto-conical. Injection nozzle (1) according to one of claims 1 to 8, characterized in that the at least one injection hole (10) in its overall length comprises a plurality of functional areas (A - E) which are arranged on the same axis sequentially and rotationally symmetrical. Injection nozzle (1) according to claim 9, characterized in that a first functional region (A) has the inlet opening (13), a second functional region (B) which comprises at least one pre-chamber (14), a third functional region (C) the at least one constriction (15), a fourth functional area (D) has the guide channel (17) and a fifth functional area (E) comprises the outlet opening (18). Injection nozzle (1) according to claim 10, characterized in that at least one functional area (AE) is provided several times. Injection nozzle (1) according to claim 10 or 11, characterized in that the bottle-neck-shaped function package (AE) is introduced in modulated drilling operations from the outside (20) inwards (13, 14, 16). Injection nozzle (1) according to claim 10 or 11, characterized in that the bottle-neck-shaped function package (AE) is combined in a structural unit and is pressed into a cylindrical injection hole. Injection nozzle (1) according to one of the preceding claims, characterized in that the substantially bottle-like inner contour of the injection hole (10) is further dependent at least on the internal shape, the volume, the air circulation and the combustion pressure of an associated combustion chamber of the internal combustion engine. Spray-hole mold, which has a substantially bottle-shaped inner contour, of a spray hole (10) of an injection nozzle (1) according to one of the preceding claims.

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