DE102022114238A1 - Purging device, gas injector, internal combustion engine and method for operating an internal combustion engine - Google Patents

Abstract

The disclosure relates to a technology for flushing a gas injector (100) with a flushing fluid (SF). The gas injector (100) is designed to inject combustible gas, in particular hydrogen, into a combustion chamber (410) of an internal combustion engine (1) and comprises an injector switching valve (110) that opens inwards. 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 inflow opening (130) for supplying a flushing fluid (SF) into the intermediate volume (120). By flushing, the temperature prevailing in the intermediate volume (120) can be reduced. In addition, flushing can reduce the reactivity of the gas mixture present in the intermediate volume (120) and prevent the flame from spreading into the intermediate volume.

Description

The invention relates to a flushing device for a gas injector, a gas injector for injecting a combustible 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.

The present disclosure describes the injection of hydrogen as an example. All statements regarding hydrogen can be applied to any combustible gases. A combustible gas can contain one component or be a combustible gas mixture with several components. The subject matter of the disclosure may relate to the injection of any combustible gases, for example comprising hydrogen and/or methane.

From the prior art, a gas injector for injecting hydrogen into a combustion chamber of an internal combustion engine is known with an inwardly opening switching valve for controlling the flow of hydrogen through the gas injector into the combustion chamber and with a nozzle for dispensing the hydrogen into the combustion chamber, the nozzle being downstream is arranged to the switching valve

An inwardly opening switching valve is preferably used because it has greater design freedom with regard to the injection openings in the nozzle compared to an outwardly opening switching valve. For example, several nozzle openings can be provided. In addition, the arrangement of the nozzle openings and their shape can be adjusted. This design freedom makes it possible to specifically influence the injection behavior of the hydrogen into the combustion chamber. For example, this can result in a more even distribution of hydrogen and oxygen-containing gas in the combustion chamber and thus a reduction in nitrogen oxide emissions. Furthermore, an inwardly opening switching valve enables greater hydrogen penetration into the combustion chamber.

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. The 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 continue from the combustion chamber into the intermediate volume of the gas injector. An explosive flame formation in the intermediate volume can damage the gas injector. In addition, an increased temperature load within the intermediate volume can damage the gas injector. In addition, an increased temperature in the intermediate volume can cause uncontrolled, explosive flame formation in the gas injector.

• - Injektion, wobei der Brennkammer Wasserstoff zugeführt wird,
• - Ansaugung, wobei der Brennkammer sauerstoffhaltiges Gas zugeführt wird,
• - Verdichtung, wobei das in der Brennkammer enthaltene Gasgemisch komprimiert wird,
• - Expansion, wobei das in der Brennkammer enthaltene Gasgemisch explosionsartig expandiert,
• - Ausstoßung, wobei das in der Brennkammer enthaltene Gasgemisch aus der Brennkammer abgeführt wird.

A method for operating an internal combustion engine is also known from the prior art, which includes 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.

Only during the injection does an active gas exchange take place in the intermediate volume of the gas injector due to the hydrogen flow into the combustion chamber. During the phases in which no injection is carried out, 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 the majority of the process time. The gas mixture heated during expansion remains in the intermediate volume of the gas injector, particularly during ejection and suction.

It is the object of the present invention to provide a gas injector for injecting combustible gas, in particular hydrogen, into a combustion chamber of an internal combustion engine, an internal combustion engine comprising such a gas injector, a flushing device and a method for operating an internal combustion engine, which reduce the temperature load and the risk of explosion in the gas injector minimize.

The invention solves this problem with the features of the flushing 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.

The subject of this disclosure is a gas injector for injecting combustible gas, ins especially of hydrogen, into a combustion chamber of an internal combustion engine.

The gas injector includes an injector switching valve that opens inwards. The term switching valve includes any valves that can be actively operated. In particular, the switching valve can be operated independently of the pressure present at the valve inlet and outlet. The injector switching valve is used to control the gas flow of the combustible gas, in particular the hydrogen flow, through the gas injector. Combustible gas, in particular hydrogen, can be injected into the combustion chamber of an internal combustion engine within a defined time interval.

The gas injector includes a nozzle for delivering the combustible gas, in particular hydrogen, into the combustion chamber. The nozzle is located downstream of the injector switching valve. The term “downstream” refers to the direction of flow of the combustible gas through the gas injector. The nozzle includes a nozzle opening. The nozzle may include one or more nozzle openings. The combustible gas can be released into the combustion chamber through the nozzle opening.

The gas injector includes an intermediate volume. The intermediate volume is arranged downstream of the injector switching valve and upstream of the nozzle. The terms “downstream” and “upstream” refer to the direction of flow 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.

The gas injector includes an inflow opening for supplying a flushing fluid into the intermediate volume. The flushing fluid can include, for example, air, preferably intake air. The flushing fluid supplied can change 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 flushing fluid can be largely chemically internalized. The chemical reactivity of the gas mixture in the intermediate volume can be reduced by the flushing fluid. The risk of explosive flame formation continuing from the combustion chamber of the internal combustion engine into the intermediate volume of the gas injector can be minimized. Flame spread into the intermediate volume can be prevented. By supplying the flushing fluid, the temperature in the intermediate volume can be reduced. This can reduce the temperature stress and thus the risk of damage to the gas injector. In addition, the risk of uncontrolled, explosive flame formation in the gas injector can be reduced. In particular, hot spots in the gas injector can lead to explosive flame formation in combination with a chemically reactive gas mixture in the intermediate volume of the gas injector. This risk can be reduced by the cooling and displacement effects of the flushing fluid.

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. For example, combustion engines that operate according to the gasoline, diesel or diesel ignition jet processes can be considered.

The internal combustion engine includes an engine body including a combustion chamber. A piston moves up and down within the combustion chamber. An explosive expansion of a reactive gas mixture in the combustion chamber drives the piston, converting chemical energy into kinetic energy.

The nozzle of the gas injector is connected to the combustion chamber of the engine body. Consequently, combustible gas, in particular hydrogen, can be injected into the combustion chamber through the nozzle opening.

A reactive gas mixture is generated in the combustion chamber. The 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 an injection of combustible gas, in particular hydrogen, via the gas injector and a separate supply of the other components of the reactive gas mixture in the combustion chamber. For example, intake air can be sucked into the combustion chamber via an air inlet device with an air inlet valve. In addition, exhaust gas can also be sucked into the combustion chamber via exhaust gas recirculation. The exhaust gas has a lower oxygen concentration than air. Alternatively, the combustible gas, in particular the hydrogen, and the oxygen-containing gas can be supplied into the combustion chamber via the gas injector.

The internal combustion engine includes the gas injector described above. The internal combustion engine solves the problem according to the invention using the same features as the gas injector.

The disclosure further relates to a flushing device for flushing a gas injector injecting combustible gas, in particular hydrogen, into a combustion chamber of an internal combustion engine with a flushing fluid, in particular for flushing an intermediate volume of the gas injector. The disclosure preferably relates to a flushing device for flushing a gas injector according to the claim with a flushing fluid, in particular for flushing the intermediate volume of the gas injector according to the claim.

The gas injector can be connectable to the flushing device. Alternatively, the gas injector may include the flushing device. In a further alternative embodiment, the intermediate volume of the gas injector can be flushed without the presence of the flushing device.

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

• - Injektion, wobei der Brennkammer brennbares Gas, insbesondere Wasserstoff, zugeführt wird;
• - Ansaugung, wobei der Brennkammer sauerstoffhaltiges Gas zugeführt wird;
• - Verdichtung, wobei das in der Brennkammer enthaltene Gasgemisch komprimiert wird;
• - Expansion, wobei das in der Brennkammer enthaltene Gasgemisch explosionsartig expandiert;
• - Ausstoßung, wobei das in der Brennkammer enthaltene Gasgemisch aus der Brennkammer abgeführt wird;
• - Spülung, wobei das Zwischenvolumen im Gasinjektor im Wesentlichen während der Ansaugung und/oder während der Verdichtung mit dem Spülfluid gespült wird.

The disclosure relates to a method for operating such an internal combustion engine, comprising the steps:

• - Injection, whereby combustible gas, in particular hydrogen, is supplied to the combustion chamber;
• - Intake, where 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;
• - Flushing, whereby the intermediate volume in the gas injector is essentially flushed with the flushing fluid during suction and/or during compression.

The individual process steps take place within certain time intervals, which can overlap. The piston moves up and down within the combustion chamber between a piston bottom dead center (BDC) and a piston top dead center (TDC). The TDC is spaced a smaller distance from the nozzle of the gas injector than the TDC.

During ejection, the piston moves from BDC to TDC. During suction, 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.

In an operating method according to the prior art, the intermediate volume of the gas injector essentially represents a dead volume, particularly during ejection and suction, i.e. the gas heated by the previous expansion remains in the intermediate volume of the gas injector.

In the method according to the disclosure, the intermediate volume in the gas injector is essentially flushed with the flushing fluid during suction and/or during compression. In this context, this essentially means that the flushing takes place during suction and/or during compression. The flushing can also extend into the ejection process step. Purging is preferably carried out during intake, as in this phase a negative pressure is created in the combustion chamber due to the downward movement of the piston from TDC to BDC. This negative pressure promotes a fluid flow of the flushing fluid from the inflow 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. The flushing time interval preferably extends over the entire suction time interval.

The time interval for injection is preferably within the time interval for suction and/or compression. The start of the flushing time interval is preferably before the start of the injection time interval. Consequently, gas exchange takes place in the intermediate volume over a longer period of time compared to the method according to the prior art. The temperature in the intermediate volume can be further reduced. The end of the flushing time interval is preferably after the end of the injection time interval. This can ensure that the combustible gas, in particular hydrogen, located in the intermediate volume of the gas injector is displaced by the flushing fluid before the next expansion time interval begins. Consequently, the gas mixture located in the intermediate volume of the gas injector is less reactive during the expansion time interval. In addition, the gas mixture in the gas injector is further cooled.

The aforementioned aspects can be used alone or in combination to solve the task. Additional advantageous embodiments of the fuel injector according to the disclosure are disclosed in the further subclaims.

The invention is shown by way of example and schematically in the drawings.

• 1: Gasinjektor gemäß Stand der Technik
• 2: Gasinjektor gemäß einer ersten Ausführungsform der Offenbarung, umfassend ein Injektorschaltventil, eine Einströmöffnung zum Zuführen eines Spülfluids und eine Düse
• 3: Verbrennungsmotor gemäß einer ersten Ausführungsform der Offenbarung, umfassend einen Gasinjektor, wie in 2 dargestellt
• 4: Verfahren gemäß einer ersten Ausführungsform zum Betreiben eines Verbrennungsmotors, wie in 3 dargestellt, umfassend die Verfahrensschritte:
  1. a) Ansaugung, Spülung
  2. b) Verdichtung
  3. c) Expansion
  4. d) Ausstoßung
• 5: Ventilhub abhängig von der Kolbenposition bei einem offenbarungsgemäßen Verfahren,
• 6: Temperaturverlauf im Zwischenvolumen bei einem offenbarungsgemäßen Verfahren
• 7: Gasinjektor gemäß einer zweiten Ausführungsform der Offenbarung, umfassend ein Injektorschaltventil, eine Einströmöffnung zum Zuführen eines Spülfluids, ein Injektorrückschlagventil und eine Düse
• 8: Verbrennungsmotor gemäß einer zweiten Ausführungsform der Offenbarung, umfassend einen Gasinjektor, wie in 7 dargestellt

List of characters:

• 1 : State-of-the-art gas injector
• 2 : Gas injector according to a first embodiment of the disclosure, comprising an injector switching valve, an inflow opening for supplying a flushing fluid and a nozzle
• 3 : Internal combustion engine according to a first embodiment of the disclosure, comprising a gas injector, as in 2 shown
• 4 : Method according to a first embodiment for operating an internal combustion engine, as in 3 shown, comprising the process steps:
  1. a) Suction, flushing
  2. b) Compaction
  3. c) expansion
  4. d) expulsion
• 5 : Valve lift depending on the piston position in a method according to the disclosure,
• 6 : Temperature profile in the intermediate volume in a method according to the disclosure
• 7 : Gas injector according to a second embodiment of the disclosure, comprising an injector switching valve, an inflow opening for supplying a flushing fluid, an injector check valve and a nozzle
• 8th : Internal combustion engine according to a second embodiment of the disclosure, comprising a gas injector as in 7 shown

A gas injector for injecting hydrogen into a combustion chamber of an internal combustion engine according to the prior art is exemplified in 1 shown. The gas injector (100) comprises an inwardly opening injector switching valve (110) for controlling the flow of hydrogen through the gas injector into the combustion chamber and a nozzle (140) for dispensing the hydrogen into the combustion chamber, the nozzle (140) being downstream of the injector switching valve (110). is arranged. 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).

In 2 A gas injector (100) according to the disclosure is shown as an example for injecting combustible gas, in particular hydrogen, into a combustion chamber of an internal combustion engine according to a first embodiment.

The in 2 Gas injector (100) shown comprises an inwardly opening injector switching valve (110) for controlling the gas flow of the combustible gas through the gas injector into the combustion chamber and a nozzle (140) for discharging the combustible gas into the combustion chamber 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), the intermediate volume (120) being arranged downstream of the injector switching valve (110) and upstream of the nozzle (140). The gas injector (100) further comprises an inflow opening (130) for supplying a flushing fluid (SF) into the intermediate volume (120).

This in 2 Injector switching valve (110) shown can comprise an actuator (111), a restoring element (113) and a valve body (115). The valve body (115) comprises a valve seat element (116) for closing and opening a valve seat opening (118). The injector switching valve (110) opens inwards, ie to open the valve and thus to enable the flow of the combustible gas through the gas injector (100), the valve body (115) is moved counter to the flow direction of the combustible gas. The flow direction of the combustible gas runs from a gas supply passage (160) upstream of the injector switching valve (110), to the injector switching valve (110), to the intermediate volume (120), to the nozzle (140). The feed pressure with which the combustible gas, in particular hydrogen, is supplied to the gas injector (100) is preferably approximately 30 bar. The actuator (111), for example, can generate a magnetic force when actuated, which affects the valve body (115) and thus the valve seat element ( 116) lifts from the valve seat opening (118) against the flow direction of the combustible gas. The valve seat opening (118) is opened. The valve body (115) is in the open position. Combustible gas, especially 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 restoring element (113), for example, can move the valve body (115) into the closed position. The restoring element (113) can, for example, comprise a spring or alternative elastic elements that generate a restoring force. The valve seat element (116) closes the valve seat opening (118). The combustible gas, especially hydrogen, cannot flow through the valve seat opening (118). The embodiment described represents an exemplary possibility of controlling the flow of the combustible 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. In these, the movement behavior of the valve body (115) can be determined via a pressure difference 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.

As in 2 shown as an example, the gas injector can additionally comprise 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 restoring element (155). The valve body (151) is designed to close and open the valve seat opening (118). If the injector switching valve (110) is in the open position, the released flow of combustible gas creates an overpressure in the valve seat opening (118), which moves the valve body (151) of the injector check valve (150) away from the valve seat opening (118) in the direction of the flow of the combustible gas. The valve seat opening (118) is opened. The valve body (151) is in the open position. Combustible gas can flow through the valve seat opening (118) towards the intermediate volume (120) and nozzle (140). If the injector switching valve (110) is closed, there is no excess pressure in the valve seat opening (118). The restoring element (155) can move the valve body (151) into the closed position. The restoring element (155) can, for example, comprise a spring or alternative elastic elements that generate a restoring force. The valve body (151) closes the valve seat opening (118). Combustible gas can flow through the valve seat opening (118). In particular, no gas can flow from the intermediate volume counter to the flow direction of the combustible gas through the valve seat opening (118) back to the gas supply passage (160). This danger exists with a gas injector without a check valve (150), especially if excess pressure arises in the combustion chamber (410). This is the case, for example, during compaction (see 4b) .

As in 2 shown, the nozzle (140) can comprise several nozzle openings (141). The plurality of nozzle openings (141) can be arranged in such a way that an ideal flushing fluid flow is ensured within the intermediate volume (120). For example, it can be ensured that the intermediate volume (120) is completely flushed with the flushing fluid (SF). Furthermore, it can be ensured that the flushing fluid (SF) flows as far as possible along the walls of the gas injector (100), which delimit the intermediate volume (120). In this way, the most effective cooling effect possible can be generated. For this purpose, the nozzle openings (141) can be evenly distributed over the nozzle (140).

As in 2 shown, the intermediate volume (120) is arranged downstream of the injector switching valve (110) and upstream of the nozzle (140). The inflow opening (130) for supplying the flushing fluid (SF) into the intermediate volume (120) can open into the intermediate volume (120). Alternatively, the inflow opening (130) can open into an area upstream of the intermediate volume (120). In particular, the inflow opening can open into an area downstream of the injector switching valve (110) and upstream of the injector check valve (150) (see 7 and 8th ).

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

In 3 An internal combustion engine (1) according to the disclosure is shown as an example according to a first embodiment. The internal combustion engine (1) shown comprises an engine body (400) comprising a combustion chamber (410) and a gas injector (1), as in 2 shown, wherein the nozzle (140) of the gas injector (100) is connected to the combustion chamber (410) of the engine body (400).

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

As in 3 shown, the flushing device (200) comprises 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 flushing fluid flow. The gas injector (100) can be connectable to the flushing device (200). The flushing device (200) can be retrofitted or exchanged. Furthermore, the gas injector (100) can include the flushing device (200) (see for example 8th ).

In the in 3 In the embodiment shown, the air inlet device (300) is connected to the flushing device (200), so that intake air (AL) from the air inlet device (300) can be supplied to the flushing device (200) and/or the gas injector (100). The flush valve (220) is in the in 3 illustrated embodiment preferably a check valve (222), which can be passively actuated by a pressure difference. If there is a negative pressure in the combustion chamber (410) during intake, the check valve (222) can be passively actuated during intake. The check valve (222) opens. Intake run (AL) can flow from the air inlet device (300) via the flushing device (200) into the intermediate volume (120) of the gas injector (100) (see 4a) . As in the enlarged view of the flush valve (220) in 3 shown, the flushing check valve (222) can include a reset element (223). Furthermore, the flushing check valve (222) can comprise a valve body (223). The operation of the flushing check valve (222) is preferably analogous to the operation of the injector check valve (150). In the 3 The embodiment disclosed is advantageous because no control for the flushing device (200) is required. In particular, the flushing check valve (222) does not require any control. Alternatively, a switching valve (221), which is actively operated, can be used as the flushing valve (220). The functioning of the switching valve (221) can be analogous to the functioning of the injector switching valve (110). The flushing device (200) preferably 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 claims. For example, the purge control device (230) can control the purge device (200) via the camshaft position or via 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 inlet device (300) and/or the air outlet device (500). Preferably, the purge valve (220) is opened substantially during suction.

In the in 3 In the embodiment shown, the flushing fluid passage (210) of the flushing device (200) opens into the inflow opening (130).

• 4a:
  • - Ansaugung, wobei der Brennkammer (410) sauerstoffhaltiges Gas zugeführt wird;
  • - Spülung, wobei das Zwischenvolumen (120) im Gasinjektor (100) im Wesentlichen während der Ansaugung mit dem Spülfluid (SF) gespült wird
• 4b:
  • - Verdichtung, wobei das in der Brennkammer (410) enthaltene Gasgemisch komprimiert wird
• 4c:
  • - Expansion, wobei das in der Brennkammer (410) enthaltene Gasgemisch explosionsartig expandiert
• 4d:
  • - Ausstoßung, wobei das in der Brennkammer (410) enthaltene Gasgemisch aus der Brennkammer abgeführt wird;

In 4 A method for operating an internal combustion engine (1) according to a first embodiment is shown as an example, comprising the method steps:

• 4a :
  • - Suction, whereby oxygen-containing gas is supplied to the combustion chamber (410);
  • - Flushing, wherein the intermediate volume (120) in the gas injector (100) is essentially flushed with the flushing fluid (SF) during suction
• 4b :
  • - Compression, whereby the gas mixture contained in the combustion chamber (410) is compressed
• 4c :
  • - Expansion, whereby the gas mixture contained in the combustion chamber (410) expands explosively
• 4d :
  • - Ejection, whereby the gas mixture contained in the combustion chamber (410) is removed from the combustion chamber;

• - Ausstoßung,
• - Ansaugung;
• - Verdichtung; und
• - Expansion

abhängig von der Kolbenposition dargestellt. Der Kolben (420) bewegt sich in der Brennkammer (410) zwischen dem Oberen (Kolben-)Totpunkt (OT) und dem Unteren (Kolben-)Totpunkt (UT) hin und her. Abhängig von der Kolbenposition ist in 5 die Stellung der Ventile (Ventilhub):

• - Luftauslassventil (510),
• - Lufteinlassventil (310),
• - Spülventil (220), und
• - Injektorschaltventil (110)

dargestellt.In 5 are examples of the four process steps

• - expulsion,
• - suction;
• - compaction; and
• - Expansion

shown depending on the piston position. The piston (420) moves back and forth in the combustion chamber (410) between the top (piston) dead center (TDC) and the bottom (piston) dead center (UT). Depending on the piston position is in 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.

As in 5 shown, the flushing valve (220) is essentially open during suction. Particularly at the beginning of the intake, when the air inlet valve (310) begins to open, it may be that the negative pressure created by the movement of the piston (420) from TDC to BDC in the combustion chamber (410) increases quickly. Because the air inlet valve (310) is not fully open at the start of intake, sufficient intake air cannot flow from the air inlet device (500) into the combustion chamber (410) to compensate for the negative pressure. Due to the rapidly increasing negative pressure in the combustion chamber (410) during this initial phase of intake, the flushing valve (220) opens. This effect can be increased by opening the air inlet valve (420) only after the movement has begun of the piston (420) from TDC to BDC begins. In addition, there may be excess pressure in the area of the air inlet device, which promotes the opening of the flushing valve (220). Intake air then flows through the purging device (200) into the intermediate volume (120) of the gas injector.

The air inlet valve (310) opens or closes an air inlet opening (320) to the combustion chamber (410). The diameter of the inflow opening (130) and/or the flushing fluid passage (210) is preferably 5 to 15% of the diameter of the air inlet opening (320), more preferably 7.5 to 12.5%, preferably 10%. If the diameter of the inflow opening (130) and/or the flushing fluid passage (210) is 5mm, the diameter of the air inlet opening (320) is preferably 50mm. When the air inlet valve (310) is fully open, the effectively opened area of the air inlet opening (320) is therefore much larger than the area of the inflow opening (130) or the flushing fluid passage (210). At the beginning of the suction, 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 inflow opening (130) or the flushing fluid passage (210). In particular, during this initial phase of intake, the intake air flows mainly through the flushing fluid passage (210) and/or the inflow opening (130).

The air inlet device (300) may include an intake, a compressor, a turbocharger and/or a common rail. While the boost pressure in an internal combustion engine powered by diesel is around 4 bar, the boost pressure in an internal combustion engine powered by combustible gas, in particular hydrogen, is preferably around 6 bar.

As in 5 shown, the time interval of the (injection of the combustible gas can be within the time interval of the suction. The beginning of the time interval of the purging can be before the beginning of the time interval of the injection. The end of the time interval of the purging can be after the end of the time interval of the injection. Furthermore, the injection can extend into the time interval of the compression. The injection preferably begins at the end of the suction. In addition, the time interval of the injection can lie exclusively within the time interval of the compression.

In 4a) A point in time is shown as an example in which the suction and rinsing process steps overlap. At this point in time, flushing fluid (preferably intake air) flows through the inflow opening (130) into the intermediate volume. The flushing 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).

The injection time interval may be within the suction and/or compression time interval. If the time interval of the injection is within the time interval of the flushing, the flammable gas, in particular the hydrogen, which is pressurized at a higher pressure, can cause the flushing to be interrupted during the injection, since the flushing fluid is pressurized at a lower pressure and therefore the flushing valve (220) closes. After the injection has ended, the pressure drop in the gas injector can cause flushing fluid to flow into the intermediate volume again as the flushing valve (220) opens again. This can be advantageous in order to displace the combustible gas in the intermediate volume, in particular the hydrogen, with flushing fluid before the expansion begins.

As in 5 shown as an example, the beginning of the flushing time interval can be before the beginning of the injection time interval. Preferably, the rinsing process step begins before the injection process step. More preferably, the flushing extends over large areas of the suction process step. Even before the start of the injection, the hot gas mixture in the intermediate volume is displaced by the cooler flushing fluid. Effective cooling of the intermediate volume is guaranteed. As in 6 shown, the temperature prevailing in the intermediate volume (120) can be reduced, particularly during suction and during compression. Consequently, the temperature load in the gas injector (100) is reduced over a wide range of the process. The temperature load and the resulting signs of wear in the gas injector (100) are reduced. The reduction in temperature further reduces the risk of spontaneous explosive flame formation in the gas injector (100) due to hot spots in the gas injector (100). In addition, the reactivity is reduced by the displacement of the gas mixture in the intermediate volume (120) by the flushing fluid, which also counteracts spontaneous explosive flame formation.

As in 5 Also shown as an example, the end of the rinsing time interval can be after the end of the injection time interval. The combustible gas, in particular the hydrogen, located in the intermediate volume (120) is displaced by the flushing fluid. The reactivity and the temperature of the gas mixture in the intermediate volume (120) are reduced. Especially during the subsequent expansion, the explosive flame formation and the temperature increase cannot escape 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 a compression of the gas in the combustion chamber.

In 7 A gas injector (100) according to the disclosure is shown as an example for injecting combustible gas, in particular hydrogen, into a combustion chamber of an internal combustion engine according to a further embodiment. The in 7 Gas injector (100) shown differs from that in 2 shown embodiment in that the inflow opening (130) does not open into the intermediate volume (120). In this embodiment, the inflow opening (130) preferably opens into an area 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 designed in such a way that the check valve (150) opens during intake due to the negative pressure prevailing in the combustion chamber (410). A flushing fluid (SF) can thus essentially be sucked into the intermediate volume (120) via the inflow opening (130) during suction. Furthermore, the gas injector (100) can comprise a purge valve (220), preferably a purge check valve (222). The flushing valve (220) can be designed such that it prevents gas flow from the gas injector (100) via the inflow opening (130). In particular, an escape of flammable gas, in particular hydrogen, from the inflow opening (130) can be prevented during the injection. For example, the flushing valve (220) can be designed such that it closes when there is excess pressure in the valve seat opening (118). Consequently, ambient air, for example, can be used as a flushing fluid.

In 8th an internal combustion engine (1) according to the disclosure is shown as an example according to a further embodiment. The in 8th The combustion engine (1) shown differs from that in 3 shown embodiment in that the inflow opening (130) does not open into the intermediate volume (120). In this further embodiment, the inflow opening (130) preferably opens into an area 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 installed according to the in 7 embodiment shown. The internal combustion engine (1) is compatible with any gas injectors (100) designed as claimed.

As in 8th shown as an example, the gas injector (100) can comprise a flushing device (200). The flushing device (200) comprises 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 flushing fluid flow. Preferably, the flushing valve (220) is an actively operable switching valve (221). The switching valve (221) can be designed analogously to the injector switching valve (110). The flushing device (200) may include a flushing fluid tank (240). Rinsing fluid can be stored in the rinsing fluid tank (240), preferably at an overpressure. If the flushing valve (220) is opened, the flushing fluid (SF) subjected to excess pressure can flow into the gas injector (100) through the inflow opening (130). In particular, the excess pressure can cause the injector check valve (150) to open and the flushing fluid (SF) to flow into the intermediate volume (120) through the inflow opening (130) and the valve seat opening (118). Consequently, the gas injector (100) can be flushed at a time when there is no negative pressure or there is an excess pressure in the combustion chamber. In particular, the flushing process step can extend into the ejection and/or compression process steps. Also in an internal combustion engine (1) according to the first embodiment as in 3 shown or in alternative embodiments the flushing fluid (SF) can be pressurized. By releasing the flushing fluid flow by means of a switching valve (221), the gas injector (1) can be flushed at a time when there is no negative pressure or there is an overpressure in the combustion chamber. Alternatively, purge fluid may be supplied directly from an area between an intercooler and an intake manifold of the engine. This can be advantageous since no flushing fluid tank (240) is necessary in such an embodiment. For example, the flushing fluid supplied from this area can also be pressurized.

Modifications of the invention are possible in various ways. In particular, the features shown, described or claimed for the respective exemplary embodiments can be combined with one another in any way, replaced with one another, supplemented or omitted.

Reference symbols

1

Internal combustion engine

100

gas injector

110

Injector switching valve

111

actuator

113

Restoring element

115

Valve body

116

Valve seat element

118

Valve seat opening

120

Intermediate volume

130

Inlet opening

140

jet

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

Restoring element

224

Valve body

230

Purge control device

240

Flushing fluid tank

300

Air intake device

310

Air inlet valve

320

Air intake opening

400

engine body

410

combustion chamber

420

Pistons

500

Air outlet device

510

Air outlet valve

SF

flushing fluid

AL

Intake air

H2

hydrogen

OT

Top (piston) dead center

UT

Bottom (piston) dead center

Claims (18)

Flushing device (200) for flushing an intermediate volume (120) of a gas injector (100) for injecting a combustible gas, in particular hydrogen, into a combustion chamber (410) of an internal combustion engine (1) with a flushing 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 flushing fluid flow. Flushing device after Claim 1 , wherein the flushing valve (220): - an actively operable switching valve (221); or - a check valve (222) that can be passively actuated by a pressure difference. Flushing device (200). Claim 1 or 2 , comprising a flushing control device (230) for controlling the flushing device (200), in particular for controlling the flushing valve (220). Gas injector (100) for injecting a combustible gas, in particular hydrogen, 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 discharging the combustible gas into the combustion chamber (410) comprising a nozzle opening (141), the nozzle (140) being arranged downstream of the injector switching valve (110); - an intermediate volume (120), the intermediate volume (120) being arranged downstream of the injector switching valve (110) and upstream of the nozzle (140); and - an inflow opening (130) for supplying a flushing fluid (SF) into the intermediate volume (120). Gas injector (100). Claim 4 , whereby the inflow opening (130) opens into the intermediate volume (120). Gas injector (100). Claim 4 or 5 , 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), in particular upstream of the intermediate volume (120). Gas injector (100). Claim 6 , wherein the inflow opening (130) opens into an area downstream to the injector switching valve (110) and upstream to the injector check valve (150). Gas injector (100) according to one of the preceding claims, wherein the gas injector (100) is connectable to a flushing device (200) according to one of the preceding claims. Gas injector (100) according to one of the preceding claims, comprising a flushing device (200) according to one of the preceding claims. Gas injector (100) according to one of the preceding claims, wherein the flushing fluid passage (210) of the flushing device (200) opens into the inflow opening (130). 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). Internal combustion engine (1). Claim 11 , comprising: - a flushing device (200) according to one of the preceding claims. Internal combustion engine (1). Claim 11 or 12 , comprising: - an air inlet device (300) for sucking intake air (AL) into the combustion chamber (410), comprising an air inlet valve (310) for controlling the flow of intake air into the combustion chamber (410). Internal combustion engine (1). Claim 13 , wherein the air inlet device (300) can be connected to the flushing device (200), so that intake air (AL) from the air inlet device (300) can be supplied to the flushing device (200) and / or the gas injector (100). Method for operating an internal combustion engine (1) according to one of the preceding claims, comprising the steps: - Injection, whereby combustible gas, in particular hydrogen, is supplied to the combustion chamber (410); - Suction, whereby oxygen-containing gas is supplied to the combustion chamber (410); - Compression, whereby the gas mixture contained in the combustion chamber (410) is compressed; - Expansion, whereby the gas mixture contained in the combustion chamber (410) expands explosively; - Ejection, whereby the gas mixture contained in the combustion chamber (410) is removed from the combustion chamber; - Flushing, wherein the intermediate volume (120) in the gas injector (100) is essentially flushed with the flushing fluid (SF) during suction and/or during compression. Procedure according to Claim 15 , where the time interval of injection is within the time interval of suction and / or compression. A method according to any one of the preceding claims, wherein the start of the flushing time interval is before the start of the injection time interval. A method according to any one 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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