FUEL / AIR INJECTION SYSTEM FOR COMBUSTION ENGINES, TURBINE ENGINES AND OTHER ATOMIZATION SYSTEMS

Description

[0001] The invention relates to an injection system which usefully supplements and expands the features of the application DE 10 2015 015 518 A1.

[0002] DE 10 2017 201 275 A1 discloses an internal combustion engine having a pressure accumulator from which an additional medium promoting combustion in the cylinder can be supplied to the cylinder in a controlled manner, and having an injection nozzle via which fuel can be injected into the cylinder, wherein the pressure accumulator is connected to the injection nozzle having a nozzle needle, and the additional medium can be introduced into the cylinder in a controlled manner by means of the injection nozzle. The nozzle needle can be controlled in its stroke movement such that, when a defined fuel pressure is reached, fuel and / or the additional medium can be introduced into the cylinder. It can furthermore have a medium channel in its interior via which the additional medium can be introduced into the cylinder, and it can have a radially arranged transverse bore for supplying the medium, which can be opened or closed by the stroke of the nozzle needle.The injection nozzle can be a multi-hole nozzle with a blind hole.

[0003] DE 39 36 986 A1 discloses a fuel injection valve with a nozzle body in which a nozzle needle is guided, which, against the force of a spring and against the direction of fuel flow, lifts off from a valve seat formed as a seat cone in the nozzle body with its conical seating surface. When the nozzle needle is in the closed position, the needle tip of the nozzle needle dips into a blind hole from which at least one injection hole branches off. A compressed air supply line opens into the blind hole and is designed to be closable when the nozzle needle is opened. The supply line can consist of a stepped line section running centrally in the nozzle needle and opening into the blind hole, as well as line sections branching off from the blind hole in a forked manner and opening on the spring side.

[0004] Injector development has recently witnessed a trend toward miniaturization, with components becoming significantly smaller. The diameters of the nozzle needles are now in the range of only 4 mm, and the sealing cones at the nozzle needle tip have also become correspondingly smaller.

[0005] As a result, for example, the arrangement of an air / gas groove (reference number 4 in DE 10 2015 015 518 A1) at the conical tip of the nozzle needle has become difficult and must be redesigned. The control of the compressed air supply through the stroke of the nozzle needle, a crucial feature, also requires further refinement.

[0006] Furthermore, a fuel nozzle is known from DATABASE WPI, Week 200846, Thomson Scientific, London, GB; AN 2008-H24500, XP002808846 & JP 2008 138609 A which is capable of suppressing deposits in the nozzle formed in the nozzle body and around the nozzle.

[0007] To achieve this object, a fuel / air injection system for internal combustion engines, turbine engines and other atomization systems according to claims 1 or 4 is proposed, which comprises an injection injector and an injection nozzle with a nozzle body and at least one nozzle hole, a nozzle needle which can be moved in a controlled manner by the injection injector, as well as at least one fuel channel and at least one air channel, wherein the nozzle needle has a sealing surface at its tip which, in a closed position of the nozzle needle, cooperates in a sealing manner with a sealing seat of the injection nozzle, and wherein a blind hole for premixing fuel and compressed air is arranged between the tip of the nozzle needle and the at least one nozzle hole in the nozzle body, and both media from the at least one fuel channel in the nozzle body and the at least one air channel in the nozzle needle or the nozzle body flow to this blind hole with the interposition of a check valve.

[0008] The blind hole located in front of the tip of the nozzle needle has at least one nozzle hole at its lower end, through which the fuel-air mixture ultimately enters the engine's combustion chamber. Strictly speaking, this is not a blind hole in the general, colloquial sense of the word. However, the term "blind hole" has become established as a technical term in engine technology for such a cavity located between the tip of the nozzle needle and the at least one nozzle hole. Therefore, it will be used as such below and should be understood in this sense.

[0009] A very important aspect of the invention can be seen in the fact that the blind hole is used as a premixing chamber to premix the fuel supplied to the blind hole from the fuel channel with the compressed air supplied to the blind hole from the air channel before this premixture is injected into the combustion chamber of the engine.

[0010] According to one embodiment, the fuel channel can comprise a cavity surrounding the nozzle needle, which only opens into the blind hole when the nozzle needle is in the open position. In other words, the fuel flows around the nozzle needle and is retained in front of the blind hole by the sealing seat of the nozzle needle tip in its closed position. In its open position, it is introduced into the blind hole via the then-open sealing seat, where the fuel meets the compressed air.

[0011] The air duct through which the compressed air is supplied to the blind hole can, for example, run in the nozzle body of the injection nozzle and open directly into the blind hole, whereby a check valve can be arranged directly at the blind hole or at another point in the air duct. Alternatively, the air duct can be designed so that at least part of the air duct is guided through the nozzle needle and opens into the blind hole at the tip of the nozzle needle. The air duct is formed in the nozzle needle by an annular groove, a transverse bore and a longitudinal bore. In this case, the compressed air is fed into the annular groove in an upper region of the nozzle needle, from where it passes through the transverse bore into the longitudinal bore and is guided through the longitudinal bore to the tip of the nozzle needle where it enters the blind hole.

[0012] The annular groove can advantageously be switched back and forth between an open position and a closed position as part of a mechanical valve circuit by the alternating upward and downward movement of the nozzle needle. For example, in the open position, the annular groove can be fluidly connected to a supply section of the air duct located in the nozzle body, whereby compressed air is fed into the annular groove. In the closed position, however, there is no fluid connection between the annular groove and the supply section of the air duct located in the nozzle body, so that no compressed air is fed into the annular groove.

[0013] The nozzle needle is seated, at least with its upper end (i.e., the end opposite the tip), in a sleeve fitted into the nozzle body of the injection nozzle. The sleeve has at least one control bore and / or at least one control groove belonging to the air channel. Compressed air is introduced into the annular groove in the upper area of ​​the nozzle needle through the control bore and / or the control groove when the needle is in its open position. The air is then guided to the blind hole as described above.

[0014] The size of the air volume flow through at least one air channel can be adjusted by changing the relative positions of the annular groove of the nozzle needle on the one hand and the control bore and / or the control groove of the sleeve on the other. This adjustment allows the overlap between the annular groove of the nozzle needle and the control bore and / or the control groove of the sleeve to be adjusted from "none" to "partial" to "complete."

[0015] The adjustability of the relative positions of the annular groove of the nozzle needle, on the one hand, and the control bore and / or the control groove of the sleeve, on the other, is achieved by adjusting the position of the sleeve in the axial direction of the nozzle needle. For this purpose, it can further be provided that the position of the sleeve can be moved in a controlled manner by the injection injector.

[0016] It can be particularly advantageous that the position of the sleeve is determined by a spring element on the one hand and by a hydraulic pressure in a control chamber on the other hand, this pressure being derived from the control system of the injection injector.

[0017] According to another embodiment, it can further be provided that, when the nozzle needle is closed, a continuous, controlled stream of compressed air flows into the blind hole and through the nozzle holes. This can actively counteract clogging of the very fine nozzle holes by combustion residues.

[0018] In the following, various aspects of the invention are explained in more detail with reference to exemplary embodiments and the accompanying drawings. Fig. 1 a plan view of an injection nozzle with indication of the cutting plane for the longitudinal section views of the following figures, Fig. 2 a first embodiment with an air duct partially guided through the nozzle needle, Fig. 3 a second embodiment with a fixed sleeve, Fig. 4 an embodiment according to the invention with a displaceable sleeve, Fig. 4a a variant of the embodiment according to the invention with a sleeve with control bore and control groove, and Fig. 5 a further embodiment according to the invention with an air duct leading through the nozzle body to the blind hole.

[0019] Fig. 1shows the top view of an injection nozzle with a nozzle body 1. It contains a nozzle needle 2 in the middle as well as two holes 3 for locking pins of the nozzle body 1 opposite an injection injector 4 not visible in this illustration. The line I - I shows the sectional plane through the nozzle body 1 as it is shown in the Fig. 2 to 5 is shown.

[0020] Fig. 2 shows a longitudinal section through a first embodiment with an air duct 10 partially routed through the nozzle needle 2. The nozzle body 1 of the injection nozzle is firmly screwed to the injection injector 4. When the injection nozzle is closed, the nozzle needle 2 is flush with its upper edge. From the fuel duct 5, the fuel flows via the groove / pressure shoulder 6 to the cone tip 7. From here, with the nozzle needle 2 raised, it enters the blind hole 8 under high pressure to pass through the nozzle holes 9 and trigger spray formation.

[0021] The air duct 10 leads via the annular groove 11 and the transverse bore 12 into the nozzle needle 2. Here it is connected to the longitudinal bore 13, which is arranged centrally in the nozzle needle 2 and leads directly into the blind hole 8.

[0022] When the nozzle needle 2 is lifted, the premixing of fuel and compressed air takes place in the blind hole 8.

[0023] Blind hole 8 thus replaces the air / gas groove 4 in DE 10 2015 015 518 A1. Depending on the respective conditions, blind hole 8 should be designed as a maxi-blind hole rather than a mini-blind hole. As the location of the premixing effect, it takes on a new function in injection nozzle 1.

[0024] The entire injection process therefore proceeds as follows: During the intake and compression strokes of the engine, the injection nozzle is closed, and the nozzle needle 2, as prompted by the injector control, rests firmly against its seat in the cone tip 7. Even in this state, compressed air is continuously blown through the path of air duct 10, annular groove 11, transverse bore 12, longitudinal bore 13, blind hole 8, and nozzle holes 9.

[0025] When injection begins, i.e. when the nozzle needle 2 is lifted, the premixing of fuel and compressed air and, if necessary, other substances in gaseous or liquid phase takes place in the blind hole 8.

[0026] This novel mixing process consists of the compressed air flow entering centrally into the blind hole 8 and the concentrically flowing fuel cone of a few tenths of a millimeter thickness (corresponding to the nozzle needle stroke).

[0027] As the nozzle needle 2 is raised, the air channel 10 is increasingly throttled / blocked. This prevents fuel from backflowing into the compressed air side at high fuel pressure and low compressed air levels.

[0028] At the end of injection, i.e., the closing of the nozzle needle 2, the air channel 10 is simultaneously reopened, meaning that compressed air is again blown in. This leads to a clean, air-rich combustion conclusion and keeps the nozzle holes 9 clean.

[0029] For this purpose, the compressed air supply already mentioned in DE 10 2015 015 518 A1, which can be controlled by the stroke of the nozzle needle 2, is characterized by the following new features, as described in Fig. 3 is shown.

[0030] The nozzle needle 2 is surrounded by a sleeve 14 fitted into the nozzle body 1 with minimal play, which is continuously connected to the air channel 10 on the one hand and to the annular groove 11 via a control bore 15 on the other. This allows control of when the compressed air system is temporarily shut off.

[0031] In Fig. 3 It is shown that the nozzle needle 2 has completed its full stroke and has just closed the control bore 15. A lower position of the sleeve 14 results in the compressed air system being closed earlier. To accommodate this displacement of the sleeve 14, discs 16 are arranged on both sides above and below the sleeve 14. By exchanging these discs, the height of this sleeve 14 can be adjusted.

[0032] For diesel engines with predominantly constant speed, a fixed setting of the overlap positions of air duct 10 and annular groove 11 may be possible through appropriate calculations / simulations and practical testing, thus eliminating the sleeve 14.

[0033] For variable speeds, in a further embodiment of the invention, the movement of the sleeve 14 can be integrated into the control of the injection injector 4, as shown in Fig. 4 is shown.

[0034] A spring element 17, preferably a disc spring, is inserted in place of the upper discs 16, and a control chamber 18 is located below, which is acted upon by a pressure branched off from the hydraulic system of the injection injector 4. This allows the movement of the sleeve 14 and thus the control / shut-off of the compressed air system to be adapted to the time / speed / pressure conditions of the entire system.

[0035] The control of the compressed air system must be carried out within a very short time. To ensure that this process is carried out precisely, the control bore 15 in the variant according to Fig. 4a supplemented by a control groove 15a, so that the process takes place via control edges of this control groove 15a and the annular groove 11.

[0036] The examples of the Fig. 2 to 4 also show the intervention of the injector control on the nozzle needle 2, represented here by the control pin 19.

[0037] Fig. 5 shows an embodiment in which the air duct 10 is located exclusively in the nozzle body 1 of the injection nozzle and does not run partially within the nozzle needle 2. In large diesel engines, there is sufficient space in the cylinder head even for stronger nozzle bodies 1.

[0038] In this embodiment, the air duct 10 is routed directly to the blind hole 8. A check valve 20 arranged at the blind hole 8 prevents fuel from flowing back into the compressed air system; this can also be installed at any other point along the air path 10, 11, 12, 13. Fuel / air injection system for internal combustion engines, turbine engines and other atomization systems List of reference symbols

[0039] 1Nozzle body 2Nozzle needle 3Hole locking pin 4Injector 5Fuel channel 6Groove / pressure shoulder 7Cone tip 8Blind hole 9Nozzle hole 10Air channel 11Annular groove 12Cross hole 13Longitudinal hole 14Sleeve 15Control hole 15aControl groove 16Disk 17Spring element 18Control chamber 19Control pin 20Check valve

Claims

1. Fuel / air injection system for internal combustion engines, turbine engines, and other atomisation systems, comprising an injection injector (4) and an injection nozzle with a nozzle body (1) and at least one nozzle hole (9), a nozzle needle (2) which can be moved in a controlled manner by the injection injector (4) and at least one fuel channel (5) and at least one air channel (10), the nozzle needle (2) having a sealing surface (7) at its tip, which, in a closed position of the nozzle needle (2), interacts in a sealing manner with a sealing seat of the injection nozzle (1), a blind hole (8) for premixing fuel and compressed air being arranged between the tip of the nozzle needle (2) and the at least one nozzle hole (9) in the nozzle body (1), and both media flowing from the at least one fuel channel (5) in the nozzle body (1) and the at least one air channel (10) in the nozzle needle (2) to this blind hole (8), wherein the at least one air duct (10) in the nozzle needle (2) is formed by an annular groove (11), a transverse bore (12) and a longitudinal bore (13), wherein the nozzle needle (2) is seated at least with its end opposite the tip in a sleeve (14) which is fitted in the nozzle body (1) of the injection nozzle and which has at least one control bore (15) belonging to the air duct (10) and / or at least one control groove (15a), wherein the size of an air volume flow rate flowing through the at least one air duct (10) is adjustable by changing the relative positions of the annular groove (11) of the nozzle needle (2) and the control bore (15) or / and the control groove (15a) of the sleeve (14) and wherein the position of the sleeve (14) is adjustable in the axial direction of the nozzle needle (2).

2. Fuel / air injection system according to claim 1, wherein the position of the sleeve (14) can be moved in a controlled manner by the injection injector (4).

3. Fuel / air injection system according to claim 2, wherein the position of the sleeve (14) is determined by a spring element (17) on the one hand and by a hydraulic pressure in a control chamber (18) on the other hand, this pressure being derived from the control system of the injection injector (4).

4. Fuel / air injection system for internal combustion engines, turbine engines, and other atomisation systems, comprising an injection injector (4) and an injection nozzle with a nozzle body (1) and at least one nozzle hole (9), a nozzle needle (2) which can be moved in a controlled manner by the injection injector (4) and at least one fuel channel (5) and at least one air channel (10), which are arranged in the nozzle body (1), the nozzle needle (2) having a sealing surface (7) at its tip, which, in a closed position of the nozzle needle (2), interacts in a sealing manner with a sealing seat of the injection nozzle (1), a blind hole (8) for premixing fuel and compressed air being arranged between the tip of the nozzle needle (2) and the at least one nozzle hole (9) in the nozzle body (1), and both media flow from the at least one fuel channel (5) in the nozzle body (1) and the at least one air channel (10) in the nozzle body (1) to this blind hole (8) with the interposition of a non-return valve (20).

5. Fuel / air injection system according to one of claims 1 to 4, wherein the at least one fuel channel (5) comprises a cavity which surrounds the nozzle needle (2), and which opens into the blind hole (8) only in an opening position of the nozzle needle (2).

6. Fuel / air injection system according to any one of claims 1 to 5, wherein a continuous controlled flow of pressurised air flows into the blind hole (8) and through the nozzle holes (9) when the nozzle needle (2) is closed.