Gas injector for an internal combustion engine

Abstract

The invention relates to a gas injector for an internal combustion engine, the gas injector comprising: a housing (1); an injector valve needle (3), which is arranged in said housing so as to be movable along the longitudinal axis (2) thereof, for introducing and metering a gas stream into the combustion chamber of the internal combustion engine; and an electromagnet which has a movably arranged magnet armature (5) and which is electrically energizable for the purpose of adjusting the injector valve needle (3); characterized in that the magnet armature (5), proceeding from an activated position in which it is in actuating contact with the injector valve needle (3), when electrically deenergized, can be decoupled from the injector valve needle and returned to a deactivated position, and the gas stream can be gas-tightly shut off by the magnet armature (5) in sealing contact with at least one sealing element (22) at a sealing point (21), wherein the magnet armature (5) is connected to a hollow body (30) which is arranged in the housing (8) coaxially in the gas stream and fixedly with respect to the housing and which is gas-tight and is axially elastic under tension.

Description

[0001] Gas injector for an internal combustion engine

[0002] The invention relates to a gas injector for an internal combustion engine according to the type defined in the preamble of claim 1.

[0003] DE 10 2019 205 301 A1 discloses a valve for metering a fluid, in particular a fuel injection valve for internal combustion engines. It comprises a housing and an armature of an actuator arranged in an armature chamber of the housing, as well as a valve needle actuatable by the armature along a longitudinal axis against a return spring.

[0004] Further injectors are known from DE 10 2021 206 186 A1 and DE 10 2021 213 023 A1.

[0005] The invention is therefore based on the object of proposing a gas injector of the aforementioned type in which gas leakage when the internal combustion engine is switched off is avoided or reduced to a permissible level in a structurally simple manner.

[0006] The problem is solved by the features of claim 1. Further advantageous and claimed embodiments emerge from the respective subclaims, the description, and the drawings.

[0007] Thus, a gas injector for an internal combustion engine is proposed, which has a housing and an injector valve needle arranged so as to be displaceable along its longitudinal axis for introducing and metering the gas flow into the combustion chamber of the internal combustion engine. An electrically energizable electromagnet with a displaceably arranged magnet armature is provided in the housing to adjust the injector valve needle. In order to avoid gas leaks when the internal combustion engine is switched off or to reduce them to a permissible level in a structurally simple manner, it is provided that the magnet armature can be displaced from an activated position in actuating contact with the injector valve needle in the de-energized state to a deactivated position relative to the injector valve needle, and that the gas flow can be shut off in a gas-tight manner at a sealing point by the magnet armature in sealing contact with at least one sealing element.The magnet armature is connected to a hollow body which is arranged coaxially and fixed to the housing in the gas flow and which is gas-tight and axially elastic.

[0008] Optionally, the hollow body has an opening to a valve chamber enclosed by the housing.

[0009] As a result, the gas flow at the sealing point away from the combustion chamber in the low operating temperature range can be easily and reliably sealed with at least one high-density sealing element, preferably made of plastic. This avoids the need for a seal with metal-to-metal contact, which is complex and costly to produce in the high-temperature range.

[0010] Since the magnet armature can be decoupled from the injector valve needle in the de-energized state and reset to the deactivated position with a small axial distance to the injector valve needle, axial component tolerances between the injector valve needle and the magnet armature, in particular at the needle seat and at the sealing point, can be easily compensated.

[0011] This allows the injector valve needle, in particular, to be manufactured with lower precision and also with a lower mass. The lower mass reduces the inertia of the injector valve needle and the forces generated by impacts on the needle seat, allowing the use of lower-strength materials. Alternatively, it is also possible to increase the permissible impact velocity of the injector valve needle.

[0012] In addition, the magnet armature can be accelerated from the deactivated position before the control contact with the injector valve needle, thereby reducing the adjustment time of the injector valve needle.

[0013] The connection of the magnet armature to the hollow body allows a static force resulting from the gas pressure prevailing in the gas flow to act on the magnet armature, moving it to the deactivated position, thus closing and shutting off the gas flow. Since this force increases with the gas pressure in the gas inlet area, the sealing effect at the sealing seat is enhanced with increasing gas pressure. In this way, tightness at the sealing point can be ensured even at very high gas pressure, especially in the event of a malfunction.

[0014] In a preferred embodiment of the invention, the magnet armature for the actuating contact with the injector valve needle can be directly coupled to the latter. This eliminates the need for additional components that transmit the actuating movement. Furthermore, the axial installation space can be reduced.

[0015] In a further preferred embodiment of the invention, the hydraulically effective diameter of the hollow body is equal to or larger than the contact diameter of the sealing contact between the sealing element and the contact surface formed on the sealing partner of the magnet armature. This ensures in a simple manner that the prevailing gas pressure always exerts a closing force on the magnet armature to shut off the gas flow. The closing force can be increased by increasing the outer diameter of the hollow body.

[0016] In addition, the return of the magnet armature to the deactivated position is facilitated, in particular the return spring means can be designed with reduced spring force.

[0017] The hydraulically effective diameter is understood to be, in particular, the diameter of the hollow body that is fluidically effective with regard to pressure loss and gas flow rate. For a circular flow cross-section, i.e., a circular cross-sectional shape of the hollow body, the outer diameter of the hollow body can be used as the hydraulically effective diameter. For a flow cross-section that deviates from a circular shape, the fluidically effective fictitious diameter of the hollow body, determined as an approximate value, can be determined as the hydraulically effective diameter. A particularly simple, particularly preferred design of the hollow body is achieved by a metal bellows that is designed to be elastic in the axial direction.

[0018] The sealing element is preferably made of plastic, which allows for particularly high sealing performance with low manufacturing precision. It is also advantageous to use an elastic material for the sealing element, so that manufacturing inaccuracies in the connected components can be compensated for. Sealing elements made of elastomers are particularly suitable for this purpose, although other suitable materials can also be used.

[0019] In a further preferred embodiment of the invention, the magnet armature and the housing each form a sealing seat at the sealing point for annular sealing contact with at least one sealing element. The annular sealing contact enables a high sealing effect.

[0020] A further development of the invention provides that the sealing element is designed as a seal that is easy to assemble and inexpensive to produce and ensures a high level of sealing.

[0021] Preferably, the magnet armature forms a concave sealing surface at the sealing point, which is adapted to the shape of the sealing ring and serves as a sealing seat. The sealing element, designed as a sealing ring, is accommodated in this concave sealing surface with a radially inner sealing contact. Preferably, the sealing ring is firmly mounted to the sealing surface.

[0022] In a further development of the invention, the housing forms an annular sealing surface at the sealing point, which runs diagonally radially outwards in the direction of flow of the gas flow and acts as a sealing seat, against which the sealing element can be placed in a gas-tight manner in the deactivated position. In this way, a sealing contact with a high sealing effect is achieved. In addition, in the activated position of the magnet armature and thus with the gas injector open, the sealing surface on the housing can have a flow-guiding effect to guide the gas flowing through the sealing seat between the sealing element and the housing. Alternatively, the sealing element can also be injection-molded onto the magnet armature or onto the housing at the sealing seat. It is also conceivable for the sealing element to be permanently mounted on the sealing seat on the housing as a sealing ring.

[0023] In a further preferred embodiment of the invention, the magnet armature cooperates with return spring means for returning to the deactivated position in actuating contact, and in this position, it is in annular sealing contact with a sealing element arranged in the gas flow at the sealing point. By arranging the magnet armature in direct actuating and sealing contact, additional components, particularly for force transmission or sealing, are avoided. Furthermore, a particularly compact design with a high sealing effect can be achieved with a single sealing element.

[0024] It is also advantageous if the return spring means are preferably arranged as a helical compression spring in the pole tube of the electromagnet coaxially on the outer diameter of the injector valve needle guided through the pole tube between the pole tube and the magnet armature.

[0025] Preferably, the housing in the gas inlet area is designed in several parts, comprising an intermediate housing with the sealing point formed therein and a connecting housing connected to the intermediate housing with the hollow body arranged fixedly within the housing. This can simplify, in particular, the assembly of the sealing element at the sealing point and of the hollow body at the magnet armature.

[0026] Further features of the invention will become apparent from the following description and the drawings, which further explain the present invention. They show:

[0027] Figure 1 shows a gas injector according to the invention for an internal combustion engine in deactivated operating state,

[0028] Figure 2 shows an enlarged section of Figure 1, Figure 3 shows the gas injector in activated operating state,

[0029] Figure 4 shows an enlarged section of Figure 3 with the difference that a central flow channel is not designed as a blind hole but as a through-hole.

[0030] The figures show an example of a gas injector according to the invention for an internal combustion engine. The gas injector comprises a multi-part housing 1 and an injector valve needle 3 arranged therein so as to be displaceable along its longitudinal axis 2 for introducing and metering the gas flow into the combustion chamber of the internal combustion engine (not shown). The gas injector is preferably intended for injecting hydrogen as fuel into the combustion chamber of the internal combustion engine.

[0031] To adjust the injector valve needle 3, an electrically energizable electromagnet with a magnetic coil 4 and a displaceably arranged magnetic armature 5 is provided in the housing 1. The latter and the injector valve needle 3 are arranged coaxially one behind the other in the housing 1, displaceably along the longitudinal axis 2, which also forms the displacement axis. When the magnetic coil 4 is deenergized, the magnetic armature 5 can be decoupled from the injector valve needle 3 and reset relative to it into a closed position shown in Figures 1 and 2.

[0032] At the gas inlet area 6 of the gas injector, the housing 1 is constructed in several parts, comprising an intermediate housing 7 and a connection housing 8 axially connected to the intermediate housing. The latter forms a gas connection 9 at its free end for connection to a gas supply system (not shown) of the internal combustion engine with a gas reservoir, in particular a gas tank. The gas supply system supplies the gas injector at the gas connection 9 with a gas stream, in this case hydrogen, under high pressure, preferably 40 bar.

[0033] The intermediate housing 7 is connected to a pole tube 10 of the electromagnet in the axial direction downstream of the gas flow. For this purpose, it is axially inserted, for example, pressed or welded, into the inner diameter of the pole tube 10 with the outer diameter of a fastening section. The pole tube 10 serves, on the one hand, to support and guide the magnet armature 5. On the other hand, the magnetic flux generated by the electromagnet or the magnet coil 4 is conducted through the pole tube 10. The magnet coil 4 is arranged on the outer diameter of the pole tube 10, coaxially enclosing the latter, in a magnet housing 11 fastened to the outer diameter of the pole tube 10.

[0034] A needle guide housing 13 is connected to the pole tube 10 in the axial direction toward the gas outlet 12 of the gas injector and the combustion chamber. The needle guide housing 13 is axially inserted, for example, pressed or welded, into the inner diameter of the free end of the pole tube 10 with the outer diameter of a fastening section.

[0035] The injector valve needle 3 is arranged in the pole tube 10 in a central axial first bore 14 and in the needle guide housing 13 in a central axial through-bore 15 coaxially adjoining the first bore 14. It is designed as a hollow needle with an axially continuous central axial bore 41 for the passage of the gas, in this case hydrogen. For injecting and metering the gas flow into the combustion chamber, it forms a valve body 16 at the gas outlet 12 of the gas injector, which is arranged in a valve seat 17 formed at the outlet-side end of the through-bore 15 on the needle guide housing 13. The valve body 16 and the valve seat 17 form a needle valve with a plate-shaped valve body 16, at which the gas flow entering the combustion chamber can be metered. The needle guide housing 13 is offset radially inwards on the outer diameter relative to the pole tube 10 towards the end facing the combustion chamber.

[0036] In the pole tube 10, the magnet armature 5 is arranged axially displaceably relative to the injector valve needle 3 in a second bore 18 axially adjoining the first bore 14 toward the gas inlet area 6. The second bore 18 is widened by a step 39 on its inner diameter compared to the first bore 14. The aforementioned bores 14, 18 thus form a stepped bore in the pole tube 10.

[0037] In the activated position of the magnet armature 5 according to Figures 3 and 4, the gas injector is switched to the open position and gas is fed into the combustion chamber via the needle valve formed on the valve body 16 and the valve seat 17. The magnet armature 5 can be decoupled from the injector valve needle 3 from the activated position in direct actuating contact with the injector valve needle 3, as shown in Figures 3 and 4, when the magnet coil 4 is de-energized and can be returned to the deactivated position shown in Figures 1 and 2 with a small axial distance 35 from the injector valve needle 3. In the deactivated position, the gas injector is in the closed position, in which the gas supply to the combustion chamber of the internal combustion engine is interrupted.

[0038] To return to the deactivated position according to Figures 1 and 2, the magnet armature 5 cooperates with return spring means 19 arranged in the pole tube 10. These are arranged as helical compression springs coaxially on the outer diameter of the injector valve needle 3 in a widened portion on the inner diameter of the first bore 14 on the pole tube 10 by a step radially outwardly offset, and are supported with one spring end on the step of the bore 14 and with the other spring end on the axial end face 20 of the magnet armature 5 facing the injector valve needle 3.

[0039] In the gas inlet area 6, the magnet armature 5 and the intermediate housing 7 each form a sealing surface 23, 26 as a sealing seat with a sealing element 22 (Figures 1 to 4) arranged in the gas flow, which is preferably designed as a sealing ring. For this purpose, a sealing surface 23 is formed on the axial side of the magnet armature 5 facing the intermediate housing 7, into which the sealing element 22 is received.

[0040] The sealing element 22 is preferably made of plastic, which allows for particularly high sealing performance with low manufacturing precision. An elastic material allows the sealing element 22 to compensate for manufacturing inaccuracies in the connected components. Elastomers are particularly suitable for this purpose, although other suitable materials may also be used.

[0041] The magnet armature 5 is drawn in radially inwards at the outer diameter with a step 24 and forms a central axially projecting connecting pin 25. In the area of ​​the shoulder of the connecting pin 25, the sealing surface 23 is designed as an annular circumferential recess corresponding to the shape of the sealing ring 2, in which the sealing element 22 is firmly arranged radially inwards with circumferential sealing contact.

[0042] Corresponding to the sealing surface 23 on the magnet armature 5, a cylindrical sealing surface 26 extending annularly from the inner diameter of the intermediate housing 7 is provided, extending obliquely radially outward. In this way, the sealing surface 26 is aligned radially inwardly, obliquely to the longitudinal axis 2, toward the sealing surface 23 on the magnet armature 5 and the sealing element 22 arranged thereon.

[0043] In addition, in the activated position of the magnet armature 5 according to Figures 3 and 4, thus in the open state of the gas injector, the sealing surface 26 can act in a flow-guiding manner to guide the gas flowing through the annular gap 42 between the sealing element 22 and the sealing surface 26 on the intermediate housing 8 through the sealing seat opened.

[0044] The sealing surface 26 is arranged with its radially outer end in the region of several gas inlet openings 27 arranged in a ring on the step 24 of the magnet armature 5, which gas inlet openings 27 communicate with a flow channel 28 running centrally in the magnet armature 5. Accordingly, when the sealing seat on the sealing surface 26 is open, the gas entering through the annular gap 42 is guided at the sealing surface 26 directly to the gas inlet openings 27 on the magnet armature 5. The central flow channel 28 in the magnet armature 5 can, as shown, be designed as a blind hole (Figures 1 to 3) extending from the axial end face 20 of the magnet armature 5 facing the needle. Alternatively, the flow channel 28 can also be designed as a through-hole (Figure 4).

[0045] The advantage of a through-hole design is that, during injector operation, the same pressure is applied on both sides of the connection pin 25, thus eliminating any pressure difference that would have to be overcome to open the valve. In the gas inlet area 6, the intermediate housing 7 forms a radial annular gap 29 radially inward to the outer diameter of the connection pin 25. At the annular gap 29, the gas can flow axially toward the sealing point 21.

[0046] By returning the magnet armature 5 to the deactivated position shown in Figures 1 and 2, the sealing element 22 is pressed radially outward against the sealing surface 26 on the intermediate housing 7 to form an annular sealing contact, and the gas flow entering at the sealing point 21 is blocked. The gas injector is thus in the deactivated operating state.

[0047] Due to the oblique alignment of the sealing surface 26 on the intermediate housing 7, the sealing element 22 is pressed against the sealing surface 23 on the magnet armature 5 at an angle to the longitudinal axis 2 against the step 24. This ensures a particularly secure arrangement of the sealing element 22 in the sealing seat on the sealing surfaces 23, 26, while simultaneously achieving a high sealing effect. Consequently, when the engine is switched off, gas leakage from the gas inlet area 6 into the combustion chamber of the internal combustion engine can be avoided or at least reduced to a harmless level.

[0048] The magnet armature 5 is axially connected, via the connecting pin 25 projecting axially into the connection housing 8, to a hollow body 30 arranged coaxially within the connection housing 8 in the gas flow, fixed to the housing. The hollow body 30 is inherently gas-tight and designed to be elastic in the axial direction or in the direction of movement of the magnet armature 5. It is preferably rotationally symmetrical to the longitudinal axis 2, here as a closed hollow cylinder. The hollow body 30 is preferably designed particularly easily as a metal bellows, as shown.

[0049] The arrangement of the hollow body 30 ensures that a surface on which the pressure acts opposite to the opening direction of the injector valve needle 1 is loaded with the same pressure as the sealing seat 23, 26 on the intermediate housing 7. If the diameter of the hollow body 30 is the same size as or larger than the diameter of the sealing seat, the pressure prevailing in the gas inlet area 6, particularly in the connection housing 8 in front of the sealing point 21, has a closing effect. The connection of the magnet armature 5 to the hollow body 30 enables the gas pressure prevailing in the gas inlet area 6, particularly in the connection housing 8, to act via the hollow body 30 on the magnet armature 5 and thus on the sealing seat 23, 26, a resulting static force in the direction of the movement of the magnet armature 5 into the deactivated position, thus closing the sealing position at the sealing seat of the sealing surfaces 23, 26 and shutting off the gas flow.Since this force is greater the higher the gas pressure in the gas inlet area 6, the sealing effect at the sealing seat 23, 26 is enhanced with increasing gas pressure. In this way, the tightness at the sealing seat 26 can be ensured even at very high gas pressure, especially in the event of a malfunction.

[0050] This also facilitates the return of the magnet armature 5 to the deactivated position, in particular the return spring means 19 can be designed with a correspondingly reduced spring force.

[0051] The design of the hollow body 30 can be optimized with respect to the sealing seat 21 if, preferably, the hydraulic diameter 31 of the metal bellows 30, i.e., the hydraulically effective diameter, particularly with respect to pressure loss and gas flow, is at least equal to and preferably greater than the contact diameter 32 of the annular sealing contact of the sealing element 22 with the sealing surface 26 of the intermediate housing 7. By increasing the hydraulic diameter 31 of the hollow body 30 beyond the size of the contact diameter 32 of the sealing contact, the resulting closing force can be increased.

[0052] The magnet armature 5 is axially inserted into a cup-shaped first connecting piece 33 on the hollow body 30 with the outer diameter of the free end of the connecting pin 25 and is secured, for example, by pressing or welding. On the other hand, the hollow body 30 is secured to the inner diameter of the connecting housing 8 with a second connecting piece 34, preferably by welding.

[0053] To switch to the activated position according to Figures 3 and 4, the magnetic coil

[0054] 4 is energized and the magnet armature 5 is axially attracted by the pole tube 10. As a result, the magnet armature 5 with the sealing element 22 moves from the deactivated position according to Figures 1 and 2 away from the intermediate housing 7. Consequently, the sealing seat on the sealing surfaces 23, 26 is opened with the annular gap 42 to allow gas to pass through. After the small axial displacement path 35, the magnet armature 5, with its axial end face 20 facing the injector valve needle 3, comes into direct actuating contact with the opposite end face 37 of the injector valve needle 3 and accelerates it.

[0055] After the further axial displacement 40, the magnet armature 5 reaches the activated position at the end stop 38 at the step 39 in the offset second bore 18 on the pole tube 10. The valve body 16 is moved out of the valve seat 17, and an annular gap 43 between the valve body 16 and the valve seat 17, and thus the needle valve, opens, allowing the gas, in this case hydrogen, to flow into the combustion chamber of the internal combustion engine. The gas injector is thus in the activated operating state.

[0056] In the activated operating state, the gas flows at the gas connection 9 into the connection housing 8 to the sealing seat 21 and via the gas inlet openings 27 on the magnet armature 5 into the central flow channel 28 and enters at the open end of the same into the axially opposite central bore 41 of the injector valve needle 3. The gas flows in the region of the valve body 16 from gas outlet openings 44 directed obliquely outwards towards it into the through-bore 15 on the needle guide housing 13 and through the annular gap 43 formed between the valve body 16 and the valve seat 17 into the combustion chamber.

[0057] If the current supply to the solenoid coil 4 is stopped again, the injector valve needle 3 is moved by the return spring means 45 interacting with it, and the magnet armature 5 is moved by the return spring means 19 towards the deactivated position, thus in the closing direction. The valve body 16 then reaches the valve seat 17 again and the injector valve needle 3 is stopped. The needle valve is thus closed again to the combustion chamber. At the same time, the magnet armature 5 moves further by the displacement path 35 relative to the injector valve needle 3 until, in the deactivated position (Figures 1 and 2), it presses the sealing element 22 into the sealing seat on the sealing surfaces 23, 26 at the sealing point 21 in a gas-tight manner. In the deactivated state of the gas injector, the gas supply is again shut off at the sealing point 21.The return spring means 45, which interact with the injector valve needle 3, are preferably arranged in the region of the end of the through-bore 15 in the needle guide housing 13 facing the pole tube 10. They are arranged in a recess 46, which is offset radially outward on the inner diameter of the through-bore 15, coaxial with the injector valve needle 3 on the outer diameter of the latter. The return spring means 45 are supported with one spring end in the recess 46 on the needle guide housing 13 and with the other spring end on a spring support 47 which is connected to the injector valve needle 3 in a displacement-proof manner.

[0058] List of reference symbols

[0059] Housing

[0060] Longitudinal axis

[0061] Injector valve needle

[0062] magnetic coil, electromagnet

[0063] Magnet armature, electromagnet

[0064] Gas inlet area

[0065] Intermediate housing

[0066] Junction box

[0067] Gas connection

[0068] Pole tube, electromagnet

[0069] Magnet housing, electromagnet

[0070] Gas leak

[0071] Needle guide housing first bore

[0072] Through hole

[0073] valve body

[0074] Valve seat second bore

[0075] Return spring means, helical compression spring axial face of the magnet armature

[0076] Sealing point, sealing seat

[0077] Sealing element, seal

[0078] Sealing surface on the magnet armature, sealing seat

[0079] Step on the magnet armature

[0080] connecting pin

[0081] Contact surface, sealing surface on the intermediate housing, sealing seat

[0082] Gas inlet opening on the magnet armature

[0083] Flow channel radial annular gap

[0084] Hollow body, metal bellows

[0085] Outer diameter of the hollow body, hydraulic diameter

[0086] Contact diameter of the sealing contact first connection piece second connection piece axial displacement, distance axial face of the injector valve needle

[0087] End stop

[0088] Stage axial displacement central bore in the injector valve needle

[0089] Annular gap

[0090] Annular gap

[0091] Gas outlet opening

[0092] recess

[0093] Return spring means

[0094] Spring support

Claims

Patent claims 1. Gas injector for an internal combustion engine, with a housing (1) and an injector valve needle (3) arranged displaceably therein along its longitudinal axis (2) for introducing and metering a gas flow into the combustion chamber of the internal combustion engine and an electromagnet which can be electrically energized for adjusting the injector valve needle (3) and has a displaceably arranged magnet armature (5), characterized in that the magnet armature (5) can be decoupled from an activated position in actuating contact with the injector valve needle (3) in the de-energized state and can be reset to a deactivated position and, at a sealing point (21), the gas flow can be blocked off in a gas-tight manner by the magnet armature (5) in sealing contact with at least one sealing element (22), wherein the magnet armature (5) is connected to a hollow body (30) which is arranged coaxially and fixedly with respect to the housing in the gas flow in the housing (1), which hollow body is designed to be gas-tight and axially elastic.

2. Gas injector according to claim 1, characterized in that the magnet armature (5) can be directly coupled to the injector valve needle (3) to form the actuating contact.

3. Gas injector according to one of claims 1 or 2, characterized in that the hydraulically effective diameter (31) of the hollow body (30) is equal to or greater than the contact diameter (32) of the sealing contact of the sealing element (22) with the contact surface (26) formed on the sealing partner of the magnet armature (5).

4. Gas injector according to one of claims 1 to 3, characterized in that the hollow body (30) is designed as a metal bellows.

5. Gas injector according to one of claims 1 to 4, characterized in that plastic is provided as the material for the sealing element (22).

6. Gas injector according to one of claims 1 to 5, characterized in that the magnet armature (5) and the housing (1) at the sealing point (21) each form a sealing seat (23, 26) for annular sealing contact with at least one sealing element (22).

7. Gas injector according to one of claims 1 to 6, characterized in that at the sealing point (21) the magnet armature (5) forms an annular circumferential concave sealing surface (23) as a sealing seat for the sealing element (22), in which the sealing element (22) designed as a seal is received with a radially inwardly circumferential sealing contact.

8. Gas injector according to one of claims 1 to 7, characterized in that the housing (1) forms at the sealing point (21) an annular sealing surface (26) extending obliquely radially outwards in the flow direction of the gas flow as a sealing seat, against which the sealing element (22) can be applied in a gas-tight manner in the deactivated position.

9. Gas injector according to one of claims 1 or 8, characterized in that the magnet armature (5) on the one hand cooperates with return spring means (19) for returning to the deactivated position in actuating contact and on the other hand is in annular sealing contact at the sealing point (21) with a sealing element (22) arranged in the gas flow.

10. Gas injector according to one of claims 1 to 9, characterized in that the housing (1) in the gas inlet region (6) is designed in several parts with an intermediate housing (7) with the sealing point (21) formed therein and a connection housing (8) connected to the intermediate housing with the hollow body (27) arranged therein in a housing-fixed manner.

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