Flushing device, gas injector, internal combustion engine and method for operating an internal combustion engine

Abstract

The disclosure relates to a technology for purging a gas injector (100) with a purge fluid (SF6). The gas injector (100) is designed for injecting combustible gas, in particular hydrogen, into a combustion chamber (410) of an internal combustion engine (1) and includes an inwardly opening injector switching valve (110). The gas injector (100) has an intermediate volume (120) downstream of the switching valve and upstream of the nozzle, which is always open towards the combustion chamber (410) of the internal combustion engine (1). The gas injector (100) has an inlet opening (130) for supplying a purge fluid (SF6) into the intermediate volume (120). Purging lowers the temperature prevailing in the intermediate volume (120). In addition, purging can reduce the reactivity of the gas mixture present in the intermediate volume (120) and prevent flame propagation into the intermediate volume. The figure intended for publication with the summary is Figure 3.

Description

[0001] The invention relates to a purging device for a gas injector, a gas injector for injecting a flammable gas, in particular hydrogen, into a combustion chamber of an internal combustion engine, an internal combustion engine comprising such a gas injector and a method for operating such an internal combustion engine.

[0002] The present disclosure describes, by way of example, the injection of hydrogen. All statements concerning hydrogen are applicable to any flammable gas. A flammable gas may contain a single component or be a flammable gas mixture with several components. The subject matter of the disclosure may relate to the injection of any flammable gases, for example, including hydrogen and / or methane.

[0003] A gas injector for injecting hydrogen into a combustion chamber of an internal combustion engine is known from the prior art, comprising an inwardly opening switching valve for controlling the hydrogen flow through the gas injector into the combustion chamber and a nozzle for releasing the hydrogen into the combustion chamber, wherein the nozzle is arranged downstream of the switching valve.

[0004] An inward-opening switching valve is preferred because it offers greater design freedom regarding the injection orifices in the nozzle compared to an outward-opening switching valve. For example, multiple nozzle orifices can be provided. Furthermore, the arrangement and shape of the nozzle orifices can be adapted. This design freedom allows for targeted control of the hydrogen injection behavior into the combustion chamber. For instance, a more uniform distribution of hydrogen and oxygen-containing gas in the combustion chamber can be achieved, thereby reducing nitrogen oxide emissions. Additionally, an inward-opening switching valve enables greater hydrogen penetration into the combustion chamber.

[0005] A gas injector with an inwardly opening switching valve, according to the prior art, has an intermediate volume within the gas injector downstream of the switching valve and upstream of the nozzle. This intermediate volume is always open towards the combustion chamber of the internal combustion engine. In particular, the intermediate volume is always open towards the combustion chamber via the nozzle openings, regardless of the position of the switching valve. While the gas mixture contained in the combustion chamber expands explosively, there is a risk that the explosive flame formation or the temperature increase will propagate from the combustion chamber into the intermediate volume of the gas injector. Explosive flame formation in the intermediate volume can damage the gas injector. Furthermore, an increased temperature load within the intermediate volume can damage the gas injector. An elevated temperature in the intermediate volume can also cause uncontrolled explosive flame formation within the gas injector.

[0006] Furthermore, a method for operating an internal combustion engine is known from the prior art, comprising the following steps: - Injection, whereby hydrogen is supplied to the combustion chamber, - Intake, whereby oxygen-containing gas is supplied to the combustion chamber, - Compression, whereby the gas mixture contained in the combustion chamber is compressed, - Expansion, whereby the gas mixture contained in the combustion chamber expands explosively, - Ejection, whereby the gas mixture contained in the combustion chamber is removed from the combustion chamber.

[0007] Active gas exchange occurs in the intermediate volume of the gas injector only during injection, due to the hydrogen flow into the combustion chamber. During phases without injection, no gas exchange takes place in the intermediate volume of the gas injector. The gas mixture heated by the combustion chamber remains in the intermediate volume of the gas injector for most of the process time. The gas mixture heated during expansion remains in the intermediate volume of the gas injector, particularly during exhaust and intake phases.

[0008] DE102014224341A1 discloses a gas injector for injecting a gaseous fuel into a combustion chamber via an intermediate space, wherein the gas injector comprises a valve closing element and an associated actuator, wherein a combustion chamber-side end of a valve closing element is shielded by a provided shielding element, which provides passive heat protection for the intermediate space. The document further discloses an associated internal combustion engine.

[0009] The object of the present invention is to provide a gas injector for injecting flammable gas, in particular hydrogen, into a combustion chamber of an internal combustion engine, an internal combustion engine comprising such a gas injector, a purging device and a method for operating an internal combustion engine, which minimize the temperature stress and the risk of explosion in the gas injector.

[0010] The invention solves this problem with the features of the rinsing device according to claim 1, the gas injector according to claim 4, the internal combustion engine according to claim 11 and the method according to claim 15.

[0011] The subject of this disclosure is a gas injector for injecting flammable gas, in particular hydrogen, into a combustion chamber of an internal combustion engine.

[0012] The gas injector includes an inwardly opening injector switching valve. The term switching valve encompasses any valve that can be actively actuated. In particular, the switching valve can be actuated independently of the pressure applied at the valve inlet and outlet. The injector switching valve controls the flow of combustible gas, especially hydrogen, through the gas injector. This allows combustible gas, especially hydrogen, to be injected into the combustion chamber of an internal combustion engine within a defined time interval.

[0013] The gas injector comprises a nozzle for delivering the combustible gas, in particular hydrogen, into the combustion chamber. The nozzle is arranged downstream of the injector switching valve. The term "downstream" refers to the flow direction of the combustible gas through the gas injector. The nozzle includes a nozzle opening. The nozzle may have one or more nozzle openings. The combustible gas can be delivered into the combustion chamber through the nozzle opening.

[0014] The gas injector includes an intermediate volume. This intermediate volume is located downstream of the injector switching valve and upstream of the nozzle. The terms "downstream" and "upstream" refer to the flow direction of the combustible gas through the gas injector. The intermediate volume is always open to the outside via the nozzle opening, regardless of the position of the injector switching valve.

[0015] The gas injector includes an inlet opening for supplying a purge fluid to the intermediate volume. The purge fluid can, for example, consist of air, preferably intake air. The supplied purge fluid can alter the gas composition in the intermediate volume of the gas injector. For example, the concentration of the combustible gas, in particular the hydrogen concentration, in the intermediate volume of the gas injector can be reduced. Furthermore, the purge fluid can be largely chemically inert. The chemical reactivity of the gas mixture in the intermediate volume can be reduced by the purge fluid. The risk of the explosive flame propagation from the combustion chamber of the internal combustion engine into the intermediate volume of the gas injector can be minimized. Flame propagation into the intermediate volume can be prevented. By supplying the purge fluid, the temperature in the intermediate volume can be lowered.This reduces the temperature stress and thus the risk of damage to the gas injector. Furthermore, it reduces the risk of uncontrolled, explosive flame formation within the gas injector. In particular, hot spots within the gas injector, in combination with a chemically reactive gas mixture in the intermediate volume of the gas injector, can lead to explosive flame formation. The cooling and displacement effect of the purge fluid reduces this risk.

[0016] The disclosure relates to an internal combustion engine comprising such a gas injector. The internal combustion engine is suitable for burning a combustible gas mixture, in particular a hydrogen gas mixture. Examples of suitable internal combustion engines include those based on the Otto, diesel, or diesel-ignition processes.

[0017] The internal combustion engine comprises an engine block, which includes a combustion chamber. Inside the combustion chamber, a piston moves up and down. An explosive expansion of a reactive gas mixture in the combustion chamber drives the piston, thus converting chemical energy into kinetic energy.

[0018] The nozzle of the gas injector is connected to the combustion chamber of the engine block. Consequently, combustible gas, especially hydrogen, can be injected into the combustion chamber through the nozzle opening.

[0019] A reactive gas mixture is generated in the combustion chamber. This reactive gas mixture preferably comprises the combustible gas, in particular hydrogen, and oxygen-containing gas, preferably air, oxygen-enriched air, or pure oxygen. The reactive gas mixture can be generated by injecting combustible gas, in particular hydrogen, via the gas injector and separately supplying the other components of the reactive gas mixture to the combustion chamber. For example, intake air can be drawn into the combustion chamber via an air intake device with an air intake valve. Alternatively, exhaust gas can also be drawn into the combustion chamber via exhaust gas recirculation. The exhaust gas has a lower oxygen concentration than air. Alternatively, the combustible gas, in particular hydrogen, and the oxygen-containing gas can be supplied to the combustion chamber via the gas injector.

[0020] The internal combustion engine comprises the gas injector described above. The internal combustion engine solves the problem according to the invention by means of the same features as the gas injector.

[0021] The disclosure further relates to a purging device for purging a gas injector for injecting flammable gas, in particular hydrogen, into a combustion chamber of an internal combustion engine with a purging fluid, in particular for purging an intermediate volume of the gas injector. Preferably, the disclosure relates to a purging device for purging a gas injector according to the claim with a purging fluid, in particular for purging the intermediate volume of the gas injector according to the claim.

[0022] The gas injector can be connected to the purging device. Alternatively, the gas injector can include the purging device. In a further alternative embodiment, the intermediate volume of the gas injector can be purged without the presence of the purging device.

[0023] The flushing device includes a flushing fluid passage for supplying the flushing fluid to the intermediate volume of the gas injector and a flushing valve for controlling the flushing fluid flow.

[0024] The disclosure relates to a method for operating such an internal combustion engine, comprising the steps: - Injection, whereby flammable gas, in particular hydrogen, is supplied to the combustion chamber; - Intake, whereby oxygen-containing gas is supplied to the combustion chamber; - Compression, whereby the gas mixture contained in the combustion chamber is compressed; - Expansion, whereby the gas mixture contained in the combustion chamber expands explosively; - Ejection, whereby the gas mixture contained in the combustion chamber is removed from the combustion chamber; - Purging, whereby the intermediate volume in the gas injector is essentially purged with the purging fluid during the intake and / or compression phases.

[0025] The individual process steps take place within specific time intervals, which can overlap. The piston moves up and down within the combustion chamber between bottom dead center (BDC) and top dead center (TDC). TDC is located closer to the gas injector nozzle than BDC.

[0026] During exhaust, the piston moves from bottom dead center (BDC) to top dead center (TDC). During intake, the piston moves from TDC to BDC. During compression, the piston moves from BDC to TDC. During expansion, the piston moves from TDC to BDC.

[0027] In a state-of-the-art operating procedure, the intermediate volume of the gas injector, particularly during discharge and intake, essentially represents a dead volume, i.e., the gas heated by the preceding expansion remains in the intermediate volume of the gas injector.

[0028] In the disclosed process, the intermediate volume in the gas injector is purged with the purge fluid essentially during the intake and / or compression phases. "Essentially" in this context means that the purging takes place during the intake and / or compression phases. The purging can also extend into the exhaust phase. Purging preferably occurs during the intake phase because, during this phase, the downward movement of the piston from top dead center (TDC) to bottom dead center (BDC) creates a vacuum in the combustion chamber. This vacuum promotes a flow of the purge fluid from the inlet opening of the gas injector to the nozzle opening of the gas injector in the direction of the combustion chamber. Consequently, gas exchange takes place in the intermediate volume. Preferably, the purging time interval extends over the entire intake time interval.

[0029] The injection time interval preferably lies within the intake and / or compression time interval. The purging time interval preferably begins before the injection time interval. Consequently, gas exchange takes place in the intermediate volume over a longer period compared to the prior art method. The temperature in the intermediate volume can be reduced further. The purging time interval preferably ends after the injection time interval. This ensures that the flammable gas, particularly hydrogen, in the intermediate volume of the gas injector is displaced by the purging fluid before the next expansion time interval begins. Consequently, the gas mixture in the intermediate volume of the gas injector is less reactive during the expansion time interval. Furthermore, the gas mixture in the gas injector is cooled further.

[0030] The aforementioned aspects can each be used individually or in combination to solve the problem. Further advantageous embodiments of the fuel injector according to the disclosure are disclosed in the dependent claims.

[0031] The invention is illustrated in the drawings in an exemplary and schematic manner. List of characters: Fig. 1: Gas injector according to the state of the art Fig. 2: Gas injector according to a first embodiment of the disclosure, comprising an injector switching valve, an inlet opening for supplying a purge fluid and a nozzle Fig. 3: Internal combustion engine according to a first embodiment of the disclosure, comprising a gas injector as shown in Fig. 2 shown Fig. 4: Method according to a first embodiment for operating an internal combustion engine, as in Fig. 3. The process steps are shown in detail below: a) Suction, flushing b) Compaction c) Expansion d) Expulsion Fig. 5: Valve lift dependent on piston position in a method as disclosed, Fig. 6: Temperature profile in the intermediate volume during a process according to the disclosure Fig. 7: Gas injector according to a second embodiment of the disclosure, comprising an injector switching valve, an inlet opening for supplying a purge fluid, an injector check valve and a nozzle Fig. 8: Internal combustion engine according to a second embodiment of the disclosure, comprising a gas injector as shown in Fig. 7 shown

[0032] A gas injector for injecting hydrogen into a combustion chamber of an internal combustion engine, according to the state of the art, is exemplified in Fig. Figure 1 shows the gas injector (100) comprising an inwardly opening injector switching valve (110) for controlling the hydrogen flow through the gas injector into the combustion chamber and a nozzle (140) for delivering the hydrogen into the combustion chamber, the nozzle (140) being arranged downstream of the injector switching valve (110). The gas injector further comprises an intermediate volume (120), the intermediate volume (120) being arranged downstream of the injector switching valve (110) and upstream of the nozzle (140).

[0033] In Fig. Figure 2 shows an exemplary gas injector (100) according to the disclosure for injecting flammable gas, in particular hydrogen, into a combustion chamber of an internal combustion engine according to a first embodiment.

[0034] The in Fig. The gas injector (100) shown comprises an inwardly opening injector switching valve (110) for controlling the flow of combustible gas through the gas injector into the combustion chamber and a nozzle (140) for delivering the combustible gas into the combustion chamber, the nozzle (140) comprising a nozzle opening (141), wherein the nozzle (140) is arranged downstream of the injector switching valve (110). The gas injector further comprises an intermediate volume (120), wherein the intermediate volume (120) is arranged downstream of the injector switching valve (110) and upstream of the nozzle (140). The gas injector (100) further comprises an inlet opening (130) for supplying a purge fluid (SF) into the intermediate volume (120).

[0035] The in Fig. The injector switching valve (110) shown in Figure 2 can comprise an actuator (111), a return element (113), and a valve body (115). The valve body (115) includes a valve seat element (116) for closing and opening a valve seat opening (118). The injector switching valve (110) opens inwards; that is, to open the valve and thus release the flow of the flammable gas through the gas injector (100), the valve body (115) is moved against the flow direction of the flammable gas. The flow direction of the flammable gas is from a gas supply passage (160) upstream of the injector switching valve (110), to the injector switching valve (110), to the intermediate volume (120), and to the nozzle (140). Preferably, the supply pressure at which the flammable gas, in particular hydrogen, is supplied to the gas injector (100) is approximately 30 bar.For example, when actuated, the actuator (111) can generate a magnetic force that lifts the valve body (115), and thus the valve seat element (116), away from the valve seat opening (118) against the flow direction of the flammable gas. The valve seat opening (118) opens. The valve body (115) is in the open position. Flammable gas, in particular hydrogen, can flow through the valve seat opening (118). If the actuator (111) is not actuated and no magnetic force acts on the valve body (115), the return element (113), for example, can move the valve body (115) into the closed position. The return element (113) can, for example, comprise a spring or alternative elastic elements that generate a return force. The valve seat element (116) closes the valve seat opening (118). The flammable gas, in particular hydrogen, cannot flow through the valve seat opening (118).The described embodiment represents an exemplary way of controlling the flow of the flammable gas through the gas injector (100). The gas injector (100) according to the disclosure is compatible with alternative switching valves. For example, hydraulically coupled switching valves can be used. With these, the movement of the valve body (115) can be controlled by a pressure differential between a pressure in a control chamber at the dorsal end of the valve body and a pressure in an injection chamber at the distal end.

[0036] As in Fig. As shown in Figure 2 by way of example, the gas injector can additionally include an injector check valve (150). The injector check valve (150) is preferably arranged upstream of the nozzle (140), in particular upstream of the intermediate volume (120), and downstream of the injector switching valve (110). In particular, the injector check valve (150) is arranged downstream of the valve seat opening (118). The injector check valve (150) can be arranged within the intermediate volume (120). The injector check valve (150) comprises a valve body (151) and a return element (155). The valve body (151) is configured to close and open the valve seat opening (118).When the injector switching valve (110) is in the open position, the released flow of flammable gas in the valve seat opening (118) creates an overpressure that lifts the valve body (151) of the injector check valve (150) away from the valve seat opening (118) in the direction of the flammable gas flow. The valve seat opening (118) opens. The valve body (151) is in the open position. Flammable gas can flow through the valve seat opening (118) towards the intermediate volume (120) and nozzle (140). When the injector switching valve (110) is closed, there is no overpressure in the valve seat opening (118). The return element (155) can move the valve body (151) to the closed position. The return element (155) can, for example, comprise a spring or alternative elastic elements that generate a return force. The valve body (151) closes the valve seat opening (118).Flammable gas can flow through the valve seat opening (118). In particular, no gas from the intermediate volume can flow back through the valve seat opening (118) to the gas supply passage (160) against the flow direction of the flammable gas. This danger exists with a gas injector without a check valve (150), especially if overpressure develops in the combustion chamber (410). This is the case, for example, during compression (see ). Fig. 4b).

[0037] As in Fig. As shown in Figure 2, the nozzle (140) can comprise several nozzle openings (141). The multiple nozzle openings (141) can be arranged such that an ideal flushing fluid flow is ensured within the intermediate volume (120). For example, this ensures that the intermediate volume (120) is completely flushed with the flushing fluid (SF). Furthermore, it ensures that the flushing fluid (SF) flows as close as possible to the walls of the gas injector (100) that define the intermediate volume (120). This allows for the most effective cooling effect possible. For this purpose, the nozzle openings (141) can be evenly distributed across the nozzle (140).

[0038] As in Fig. As shown in Figure 2, the intermediate volume (120) is located downstream of the injector switching valve (110) and upstream of the nozzle (140). The inlet opening (130) for supplying the purge fluid (SF) into the intermediate volume (120) can open into the intermediate volume (120). Alternatively, the inlet opening (130) can open into a region upstream of the intermediate volume (120). In particular, the inlet opening can open into a region downstream of the injector switching valve (110) and upstream of the injector check valve (150) (see Figure 2). Fig. 7 and Fig. 8).

[0039] The intermediate volume (120) can be primarily limited by the nozzle (140). Furthermore, the intermediate volume can be connected to the gas supply passage (160) via the valve seat opening (118).

[0040] In Fig. Figure 3 shows an example of an internal combustion engine (1) according to a first embodiment as disclosed. The illustrated internal combustion engine (1) comprises an engine body (400) including a combustion chamber (410) and a gas injector (1), as shown in Figure 3. Fig. 2 shown, wherein the nozzle (140) of the gas injector (100) is connected to the combustion chamber (410) of the engine body (400).

[0041] As in Fig. As shown in Figure 3, the internal combustion engine (1) can include a purging device (200) for purging the intermediate volume (120) of the gas injector (100) according to a first embodiment. Furthermore, the internal combustion engine (1) can include an air intake device (300) for drawing intake air (AL) into the combustion chamber (410). The air intake device (300) can include an air intake valve (310) for controlling the intake air flow into the combustion chamber (410). In addition, the internal combustion engine (1) can include an air outlet device (500) for releasing the gas mixture from the combustion chamber (410). The air outlet device (500) can include an air outlet valve (510) for controlling the gas mixture flow from the combustion chamber (410).

[0042] As in Fig. As shown in Figure 3, the purging device (200) comprises a purging fluid passage (210) for supplying the purging fluid (SF) to the intermediate volume (120) of the gas injector (100) and a purging valve (220) for controlling the purging fluid flow. The gas injector (100) can be connected to the purging device (200). The purging device (200) can be retrofittable or interchangeable. Furthermore, the gas injector (100) can include the purging device (200) (see, for example, Figure 3). Fig. 8).

[0043] In the Fig. In the embodiment shown in Figure 3, the air inlet device (300) is connected to the purge device (200) so that intake air (AL) from the air inlet device (300) can be supplied to the purge device (200) and / or the gas injector (100). The purge valve (220) is located in the Fig. In the embodiment shown in Figure 3, a check valve (222) is preferably provided, which can be passively actuated by a pressure differential. If a negative pressure prevails in the combustion chamber (410) during intake, the check valve (222) can be passively actuated during intake. The check valve (222) opens. Intake air (AL) can flow from the air inlet device (300) via the purge device (200) into the intermediate volume (120) of the gas injector (100) (see Figure 3). Fig. 4a). As shown in the enlarged illustration of the flushing valve (220) in Fig. As shown in Figure 3, the flushing check valve (222) can include a return element (223). Furthermore, the flushing check valve (222) can include a valve body (223). The operating principle of the flushing check valve (222) is preferably analogous to the operating principle of the injector check valve (150). The Fig. The disclosed embodiment 3 is advantageous because no control unit is required for the flushing device (200). In particular, the flushing check valve (222) does not require a control unit. Alternatively, a switching valve (221) that is actively actuated can be used as the flushing valve (220). The operation of the switching valve (221) can be analogous to the operation of the injector switching valve (110). Preferably, the flushing device (200) comprises a flushing control device (230) for controlling the flushing device (200), in particular for controlling the flushing valve (220) or the switching valve (221). The flushing control device (230) is particularly suitable for carrying out a method according to the claim. For example, the flushing control device (230) can control the flushing device (200) via the camshaft position or the piston position.The purge control device (230) can be connected to a control device of the internal combustion engine (1) and / or the gas injector (100) and / or the air intake device (300) and / or the air outlet device (500). Preferably, the purge valve (220) is opened substantially during the intake stroke.

[0044] In the Fig. In the embodiment shown in Figure 3, the flushing fluid passage (210) of the flushing device (200) opens into the inlet opening (130).

[0045] In Fig. Figure 4 shows an exemplary method for operating an internal combustion engine (1) according to a first embodiment, comprising the following process steps:

[0046] Fig. 4a: - Intake, wherein oxygen-containing gas is supplied to the combustion chamber (410); - Purging, wherein the intermediate volume (120) in the gas injector (100) is essentially purged with the purging fluid (SF) during the intake.

[0047] Fig. 4b: - Compression, whereby the gas mixture contained in the combustion chamber (410) is compressed

[0048] Fig. 4c: - Expansion, wherein the gas mixture contained in the combustion chamber (410) expands explosively

[0049] Fig. 4d: - Ejection, whereby the gas mixture contained in the combustion chamber (410) is discharged from the combustion chamber;

[0050] In Fig. The four process steps are 5 examples. - Expulsion, - Intake; - Compaction; and - Expansion dependent on piston position. The piston (420) moves back and forth in the combustion chamber (410) between top dead center (TDC) and bottom dead center (BDC). Depending on the piston position, in Fig. 5. The position of the valves (valve lift): - Air outlet valve (510), - Air inlet valve (310), - Flush valve (220), and - Injector switching valve (110) shown.

[0051] As in Fig. As shown in Figure 5, the purge valve (220) is essentially open during the intake stroke. Particularly at the beginning of the intake stroke, when the air inlet valve (310) begins to open, the vacuum generated in the combustion chamber (410) by the movement of the piston (420) from top dead center (TDC) to bottom dead center (BDC) can increase rapidly. Because the air inlet valve (310) is not fully open at the beginning of the intake stroke, insufficient intake air from the air inlet device (500) can flow into the combustion chamber (410) to equalize the vacuum. Due to the rapidly increasing vacuum in the combustion chamber (410) during this initial phase of the intake stroke, the purge valve (220) opens. This effect can be intensified if the opening of the air inlet valve (420) only begins after the piston (420) has started moving from TDC to BDC. In addition, an overpressure may prevail in the area of ​​the air inlet device, which promotes the opening of the purge valve (220).Intake air then flows through the purging device (200) into the intermediate volume (120) of the gas injector.

[0052] The air inlet valve (310) opens or closes an air inlet opening (320) to the combustion chamber (410). The diameter of the inlet opening (130) and / or the scavenging fluid passage (210) is preferably 5 to 15% of the diameter of the air inlet opening (320), more preferably 7.5 to 12.5%, and preferably 10%. With a diameter of 5 mm for the inlet opening (130) and / or the scavenging fluid passage (210), the diameter of the air inlet opening (320) is preferably 50 mm. When the air inlet valve (310) is fully open, the effectively open area of ​​the air inlet opening (320) is therefore much larger than the area of ​​the inlet opening (130) or the scavenging fluid passage (210). At the beginning of the intake, while the air inlet valve (310) begins to open, the effectively opened area of ​​the air inlet opening (320) is initially smaller than the area of ​​the inlet opening (130) or the purge fluid passage (210).Particularly during this initial phase of the intake, the intake air flows mainly through the purge fluid passage (210) and / or the inlet opening (130).

[0053] The air intake device (300) can comprise an intake, a compressor, a turbocharger and / or a common rail. While the boost pressure in a diesel-powered internal combustion engine is approximately 4 bar, the boost pressure in an internal combustion engine powered by the combustible gas, in particular hydrogen, is preferably around 6 bar.

[0054] As in Fig. As shown in Figure 5, the injection time interval of the flammable gas can lie within the intake time interval. The start of the purging time interval can be before the start of the injection time interval. The end of the purging time interval can be after the end of the injection time interval. Furthermore, the injection can extend into the compression time interval. Preferably, the injection begins at the end of the intake. Alternatively, the injection time interval can lie exclusively within the compression time interval.

[0055] In Fig. Figure 4a) shows an example of a point in time at which the intake and purging process steps overlap. At this point, purging fluid (preferably intake air) flows through the inlet opening (130) into the intermediate volume. The purging fluid can serve to cool the gas injector (100), in particular the intermediate volume (120) and the nozzle (140), which are exposed to high temperatures from the combustion chamber (410).

[0056] The injection time interval can lie within the intake and / or compression time interval. If the injection time interval lies within the purge time interval, the flammable gas, particularly hydrogen, which is subjected to a higher pressure during injection, can cause the purge to be interrupted because the purge fluid is subjected to a lower pressure and therefore the purge valve (220) closes. After the injection is complete, the pressure drop in the gas injector can cause purge fluid to flow back into the intermediate volume because the purge valve (220) reopens. This can be advantageous for displacing the flammable gas, particularly hydrogen, in the intermediate volume before the start of expansion by purge fluid.

[0057] As in Fig. As illustrated in Figure 5, the beginning of the purging time interval can precede the beginning of the injection time interval. Preferably, the purging process step begins before the injection process step. More preferably, the purging extends over a large portion of the intake process step. Even before the injection begins, the hot gas mixture in the intermediate volume is displaced by the cooler purging fluid. Effective cooling of the intermediate volume is ensured. As shown in Figure 5, the purging process step can be performed before the injection process step begins. Fig. As shown in Figure 6, the temperature prevailing in the intermediate volume (120) can be reduced, particularly during intake and compression. Consequently, the temperature load in the gas injector (100) is lowered over a wide range of the process. This reduces the temperature load and the resulting wear in the gas injector (100). Furthermore, the temperature reduction reduces the risk of spontaneous, explosive flame formation in the gas injector (100) due to hot spots. Additionally, the displacement of the gas mixture in the intermediate volume (120) by the purge fluid reduces its reactivity, which also counteracts spontaneous, explosive flame formation.

[0058] As in Fig. As further illustrated in Figure 5, the end of the purging interval can be after the end of the injection interval. The combustible gas, particularly hydrogen, located in the intermediate volume (120) is displaced by the purging fluid. The reactivity and temperature of the gas mixture in the intermediate volume (120) are reduced. Particularly during the subsequent expansion, the explosive flame formation and temperature increase cannot propagate from the combustion chamber (410) into the intermediate volume (120). The explosive flame formation in the combustion chamber during expansion can be triggered, for example, by a spark plug. Alternatively, the explosive flame formation in the combustion chamber can also be triggered by compression of the gas in the combustion chamber.

[0059] In Fig. Figure 7 shows an exemplary gas injector (100) according to the disclosure for injecting flammable gas, in particular hydrogen, into a combustion chamber of an internal combustion engine according to a further embodiment. The Fig. The gas injector shown in Figure 7 (100) differs from the one shown in Figure 7. Fig. In the embodiment shown in Figure 2, the inlet opening (130) does not open into the intermediate volume (120). Preferably, in this embodiment, the inlet opening (130) opens into a region between the injector switching valve (110) and the injector check valve (150), in particular into the valve seat opening (118). The injector check valve (150) can be configured such that, during intake, the check valve (150) opens due to the negative pressure prevailing in the combustion chamber (410). A purge fluid (SF) can thus be drawn into the intermediate volume (120) essentially during intake via the inlet opening (130). Furthermore, the gas injector (100) can include a purge valve (220), preferably a purge check valve (222). The purge valve (220) can be designed in such a way as to prevent a gas flow from the gas injector (100) through the inlet opening (130).In particular, the escape of flammable gas, especially hydrogen, from the inlet opening (130) during injection can be prevented. For example, the purge valve (220) can be designed to close when there is overpressure in the valve seat opening (118). Consequently, ambient air, for example, can be used as the purge fluid.

[0060] In Fig. Figure 8 shows an example of an internal combustion engine (1) according to a further embodiment as disclosed. The one in Fig. The internal combustion engine (1) shown in Figure 8 differs from the one shown in Figure 8. Fig. In the embodiment shown in Figure 3, the inlet opening (130) does not open into the intermediate volume (120). Preferably, in this further embodiment, the inlet opening (130) opens into a region between the injector switching valve (110) and the injector check valve (150), in particular into the valve seat opening (118). The gas injector (1) can be operated according to the instructions in Figure 3. Fig. The internal combustion engine (1) is designed as shown in the embodiment shown in Figure 7. The internal combustion engine (1) is compatible with any gas injectors (100) designed according to the claim.

[0061] As in Fig. As shown in Figure 8 by way of example, the gas injector (100) can include a purging device (200). The purging device (200) comprises a purging fluid passage (210) for supplying the purging fluid (SF) to the intermediate volume (120) of the gas injector (100) and a purging valve (220) for controlling the purging fluid flow. Preferably, the purging valve (220) is an actively actuated switching valve (221). The switching valve (221) can be designed analogously to the injector switching valve (110). The purging device (200) can include a purging fluid tank (240). Purging fluid can be stored in the purging fluid tank (240), preferably at an overpressure. When the purging valve (220) is opened, the purging fluid (SF) pressurized can flow into the gas injector (100) through the inlet opening (130).In particular, the overpressure can cause the injector check valve (150) to open, allowing the purge fluid (SF) to flow through the inlet port (130) and the valve seat port (118) into the intermediate volume (120). Consequently, the gas injector (100) can be purged at a time when there is no negative pressure or overpressure in the combustion chamber. In particular, the purging process step can extend into the exhaust and / or compression process steps. This also applies to an internal combustion engine (1) according to the first embodiment as shown in [reference]. Fig.As shown in Figure 3, or in alternative embodiments, the purge fluid (SF) can be pressurized. By releasing the purge fluid flow by means of a switching valve (221), the gas injector (1) can be purged at a time when there is no negative pressure or when there is positive pressure in the combustion chamber. Alternatively, purge fluid can be supplied directly from an area between an intercooler and an intake manifold of the engine. This can be advantageous because, in such an embodiment, a purge fluid tank (240) is not necessary. For example, the purge fluid supplied from this area can also be pressurized.

[0062] Variations of the invention are possible in various ways. In particular, the features shown, described, or claimed for the respective embodiments can be combined, replaced, supplemented, or omitted in any way. Reference sign 1 Internal combustion engine 100 gas injectors 110 Injector switching valve 111 Actuator 113 Reset element 115 Valve bodies 116 Valve seat element 118 Valve seat opening 120 intermediate volumes 130 Inlet opening 140 nozzle 141 Nozzle opening 150 Injector check valve 160 Gas supply passage 200 flushing device 210 Flushing fluid passage 220 flush valve 221 (flushing) switching valve 222 (flushing) check valve 223 Reset element 224 Valve bodies 230 flushing control device 240 flushing fluid tank 300 air intake device 310 Air intake valve 320 Air intake opening 400 engine bodies 410 Combustion chamber 420 pistons 500 air outlet device 510 Air outlet valve SF flushing fluid AL intake air H2 hydrogen OT Top Dead Center UT Bottom dead center (bottom dead center)

Claims

[1] Purging device (200) for purging an intermediate volume (120) of a gas injector (100) for injecting a flammable gas into a combustion chamber (410) of an internal combustion engine (1) with a purging fluid (SF), comprising: - a flushing fluid passage (210) for supplying the flushing fluid (SF) into the intermediate volume (120) of the gas injector (100); and - a flushing valve (220) for controlling the flow of flushing fluid. [2] Rinsing device (200) according to claim 1, wherein the flammable gas is hydrogen. [3] Flushing device according to claim 1 or 2, wherein the flushing valve (220): - an actively actuated switching valve (221); or - includes a non-return valve (222) that can be passively actuated by a pressure difference. [4] Flushing device (200) according to claim 1, 2 or 3, comprising a flushing control device (230) for controlling the flushing device (200), in particular for controlling the flushing valve (220). [5] Gas injector (100) for injecting a flammable gas into a combustion chamber (410) of an internal combustion engine (1), comprising: - an inwardly opening injector switching valve (110) for controlling the gas flow of the combustible gas through the gas injector (100); - a nozzle (140) for delivering the combustible gas into the combustion chamber (410) comprising a nozzle opening (141), wherein the nozzle (140) is arranged downstream of the injector switching valve (110); - an intermediate volume (120), wherein the intermediate volume (120) is arranged downstream of the injector switching valve (110) and upstream of the nozzle (140); and - an inlet opening (130) for supplying a flushing fluid (SF) into the intermediate volume (120). [6] Gas injector (100) according to claim 5, wherein the flammable gas is hydrogen. [7] Gas injector (100) according to claim 5 or 6, wherein the inlet opening (130) opens into the intermediate volume (120). [8] Gas injector (100) according to claim 5, 6 or 7, comprising an injector check valve (150), wherein the injector check valve (150) is arranged downstream of the injector switching valve (110) and upstream of the nozzle (140). [9] Gas injector (100) according to claim 8, wherein the injector switching valve (110) is arranged upstream of the intermediate volume (120). [10] Gas injector (100) according to claim 8 or 9, wherein the inlet opening (130) opens into a region downstream to the injector switching valve (110) and upstream to the injector check valve (150). [11] Gas injector (100) according to one of the preceding claims, wherein the gas injector (100) is connectable to a rinsing device (200) according to one of the preceding claims. [12] Gas injector (100) according to any one of the preceding claims, comprising a rinsing device (200) according to any one of the preceding claims. [13] Gas injector (100) according to one of the preceding claims, wherein the flushing fluid passage (210) of the flushing device (200) opens into the inlet opening (130). [14] Internal combustion engine (1) comprising: - an engine body (400) comprising a combustion chamber (410); - a gas injector (100) according to one of the preceding claims, wherein the nozzle (140) of the gas injector (100) is connected to the combustion chamber (410) of the engine body (400). [15] Internal combustion engine (1) according to claim 14, comprising: - a flushing device (200) according to one of the preceding claims. [16] Internal combustion engine (1) according to claim 14 or 15, comprising: - an air inlet device (300) for drawing intake air (AL) into the combustion chamber (410), comprising an air inlet valve (310) for controlling the intake air flow into the combustion chamber (410). [17] Internal combustion engine (1) according to claim 16, wherein the air inlet device (300) can be connected to the scavenging device (200) so that intake air (AL) from the air inlet device (300) can be supplied to the scavenging device (200) and / or the gas injector (100). [18] Method for operating an internal combustion engine (1) according to any one of the preceding claims, comprising the steps: - Injection, wherein flammable gas is supplied to the combustion chamber (410); - Intake, wherein oxygen-containing gas is supplied to the combustion chamber (410); - Compression, whereby the gas mixture contained in the combustion chamber (410) is compressed; - Expansion, wherein the gas mixture contained in the combustion chamber (410) expands explosively; - Ejection, whereby the gas mixture contained in the combustion chamber (410) is discharged from the combustion chamber; - Purging, wherein the intermediate volume (120) in the gas injector (100) is essentially purged with the purging fluid (SF) during the intake and / or compression phases. [19] Method according to claim 18, wherein the flammable gas is hydrogen. [20] Method according to claim 18 or 19, wherein the injection time interval is within the intake and / or compression time interval. [21] Method according to any of the preceding claims, wherein the beginning of the rinsing time interval is before the beginning of the injection time interval. [22] Method according to any of the preceding claims, wherein the end of the rinsing time interval is after the end of the injection time interval.

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