Gas injector with a structural method having a short axial direction

Abstract

The invention comprises a magnetic actuator (2) having an armature (20), an inner magnetic pole (21) and a coil (22), a closure element (3) with a valve needle (30) for opening and closing a gas path (14) at a sealing seat (11), the closure element (3) being connected to the closure element (3), a sealed lubricant chamber (4) filled with a lubricant and in which the armature (20) is arranged, the lubricant chamber (4) ensuring lubrication of the armature (20), and a flexible seal sealing the lubricant chamber (4) against the gas path (14). The present invention relates to a gas injector for injecting a gas fuel, comprising a flexible sealing element (51), a restoring element (10) for returning a closing element (3) to an initial closed position, and a first needle guide (31) formed between a guide sleeve (9) and a valve needle (30), wherein the first needle guide (31) is arranged radially inside the flexible sealing element (51) in the lubricant chamber (4), and the restoring element (10) is arranged at least partially, in particular entirely, inside the flexible sealing element (51) in the lubricant chamber (4).

Description

Technical Field

[0001] The present invention relates to a gas injector for injecting gaseous fuels, particularly hydrogen or natural gas, etc., having an axially short and compact structural system. This gas injector is designed particularly for direct injection into the combustion chamber of an internal combustion engine.

Background Art

[0002] From the prior art, gas injectors are known in various configurations. The problem in gas injectors is essentially that, since the medium to be injected is a gas, lubrication by the medium, which is possible in fuel injectors for injecting, for example, gasoline or diesel fuel, is not possible. As a result, excessive wear occurs during operation compared to fuel injectors for liquid fuels. Furthermore, it is often necessary due to the increasing miniaturization of internal combustion engines that the injector be mounted laterally, as opposed to being mounted centrally on or near the main axis of the cylinder of the internal combustion engine.

Summary of the Invention

[0003] In contrast, the gas injector for injecting gaseous fuel according to the invention and having the features of claim 1 has the advantage that the axial structural length of this gas injector is short. Thereby, this gas injector can be arranged, in particular, laterally of the combustion chamber of an internal combustion engine. Nevertheless, this gas injector is very slim and can be provided, in particular, with a small outer diameter. This is achieved according to the invention in that the gas injector comprises a magnetic actuator with an armature, an inner pole, and a coil. The gas injector further comprises a closing element with a valve needle, which closing element releases and closes a gas path for the gaseous fuel at a valve seat. Here, the armature is connected to the closing element. Furthermore, a sealed lubricant chamber filled with lubricant and having a movable armature arranged therein is provided. Here, the lubricant ensures lubrication of the armature, so that wear does not occur on the armature during operation. The lubricant chamber includes at least one flexible sealing element, in particular a bellows, which seals the lubricant chamber against the gas path and thus ensures the axial mobility of the closing element. The gas injector further comprises a restoring element, in particular a closing spring in the form of a cylindrical spring, which restoring element returns the closing element to its initial closed position. Furthermore, a first needle guide is formed between a guide sleeve and the valve needle of the closing element. Here, the first needle guide is arranged within the lubricant chamber and inside the flexible sealing element, and the restoring element is also arranged at least partially within the flexible sealing element within the lubricant chamber. Preferably, the restoring element is entirely arranged within the flexible sealing element. Thus, the flexible sealing element, the first needle guide, and the restoring element are arranged concentrically. Thereby, the axial structural space can be saved and the overall axial length of the gas injector can be reduced. This lubricant chamber further results in a long service life of the magnetic actuator, since, in particular, wear on the needle guide, the armature, and components that can come into contact with the armature hardly occurs.

[0004] The dependent claims indicate preferred developments of the invention. The flexible sealing element is preferably a metal bellows. On the one hand, the metal bellows provides very good mobility in order to enable the axial movement of the closing element. On the other hand, the metal bellows can thereby be arranged as close as possible to the hot combustion chamber of the internal combustion engine. This can further reduce the axial length of the gas injector. Alternatively, the flexible sealing element is a plastic bellows or a membrane or a rubber element.

[0005] Particularly preferably here, the flexible sealing element is directly fixed to the valve needle and directly to the guide sleeve. In order to fix the flexible sealing element to the valve needle particularly easily, the valve needle preferably includes a fixing disk. The fixing disk can be integrally formed with the valve needle or, alternatively, can be provided as a ring disk joined to the valve needle, for example, by a welded joint.

[0006] According to a further preferred configuration of the present invention, a second needle guide part is formed between the valve needle and the guide sleeve. The second needle guide part is further away from the sealing seat of the closing element than the first needle guide part. Preferably, the second needle guide part is also arranged inside the flexible sealing element.

[0007] In order to achieve a more compact structure, the restoring element is preferably arranged entirely inside the guide sleeve. Particularly preferably, the restoring element is a cylindrical spring that abuts closely against the valve needle. Particularly preferably, the guide sleeve has a step at which one end of the restoring element is supported. Even more preferably, the other end is supported by a spring holder.

[0008] Preferably, the guide sleeve has an inner step at which one end of the restoring element is supported. According to a further preferred configuration of the present invention, the gas injector includes a gas inlet disposed on the side surface of the gas injector. Preferably, the gas inlet is disposed on the side surface of the main body of the gas injector. Thereby, the axial structural length of the gas injector can be further reduced, and the gas injector can be formed more compactly. The side gas inlet is preferably provided at an angle of 90° with respect to the longitudinal axis of the gas injector.

[0009] More preferably, the gas injector has a planar sealing seat portion. Preferably, the closing element includes a sealing disk at the end facing the combustion chamber, and this sealing disk releases one or more through holes at the valve seat. Here, the gas injector is preferably formed as an injector that opens outward. Thereby, a sealing seat portion in a plane perpendicular to the longitudinal direction of the gas injector can be provided.

[0010] Preferably, the gas injector further includes a braking mechanism disposed in the lubricant chamber, and this braking mechanism is configured to decelerate the closing element during the restoration process of the gas injector from the open state to the closed state. The braking mechanism includes a braking bolt, a damping chamber in fluid connection with the lubricant chamber, and an elastic braking element, particularly a spring. During the restoration process, the braking bolt and the elastic braking element are operatively connected to the closing element and / or the armature, and the braking bolt is further configured to displace the lubricant from the damping chamber to attenuate the restoration of the braking bolt during the restoration process. Since a part of the deceleration process is provided by the hydraulic adhesion between the braking bolt and the stopper component with which the braking bolt abuts in the open state of the gas injector, by providing the damping chamber, the vapor lock phenomenon of the liquid lubricant when the hydraulic adhesion is overcome can be prevented, and thereby wear due to cavitation in particular can be prevented.

[0011] The braking process is further supported by the acceleration of the additional mass provided by the braking mechanism. Furthermore, due to the displacement of the lubricant between the armature and the brake bolt, further deceleration is achieved. The restoration speed of the closing element can be further reduced by the friction between the guiding element and the brake bolt. All of these can reduce the impact force of the armature on the stopper and further extend the life of the armature.

[0012] More preferably, the brake bolt includes a body having a contact surface, which is disposed on the side of the body of the brake bolt facing the closing element and can be operatively connected to the closing element to act as a stopper surface. The body is preferably cylindrical. More preferably, a ring flange is disposed on the side of the body facing the closing element. This ring flange preferably acts as a stopper surface.

[0013] According to a further preferred configuration of the present invention, the elastic braking element of the braking mechanism is disposed in the damping chamber. Thereby, a particularly compact structure can be realized. The elastic braking element is preferably a compression spring, particularly a cylindrical spring.

[0014] More preferably, the damping chamber is in fluid connection with the lubricant chamber via the guiding play of the brake bolt. Preferably, the gas injector further includes a throttle portion connecting the damping chamber and the lubricant chamber. Since the lubricant moves from the damping chamber through the throttle portion and then to the lubricant chamber, this throttle portion ensures that the damping process can proceed as prescribed. The throttle portion is preferably a small connecting hole between the damping chamber and the lubricant chamber. By selecting the geometric dimensions of the connecting hole, such as the diameter and / or length of the hole, the damping behavior of the braking mechanism can be adjusted.

[0015] The gas injector more preferably further includes an armature bolt in contact with the closing element, and the armature bolt is connected to the armature. The end of the armature bolt that does not face the sealing seat portion of the gas injector is configured to contact the brake bolt in the closed state of the gas injector.

[0016] The gas injector preferably further includes an armature bolt guide portion for guiding the armature bolt. The armature bolt guide portion serves as a stopper for the brake bolt in the open state of the gas injector. In the closed state, there is a first gap between the armature bolt guide portion and the brake bolt. When opened, this first gap is overcome by the pressure of the spring of the braking mechanism acting on the brake bolt.

[0017] According to a further preferred configuration of the present invention, the gas injector includes a guide body having a guide region for guiding the brake bolt, which is disposed in the lubricant chamber. The guide body preferably has a recess, particularly at an end facing the sealing seat portion among the guide bodies for guiding the brake bolt.

[0018] Preferably, in the closed state of the gas injector, the first gap between the brake bolt and the armature bolt guide portion has a first width B, and the first width B is smaller than a second gap having a second width C between the armature and the inner pole. Here, the axial gap B between the armature bolt guide portion and the brake bolt is preferably within the range of 1% to 90% of the axial gap C between the armature and the inner pole. Particularly preferably, the axial gap B between the armature bolt guide portion and the brake bolt is smaller than 25% of the axial gap C, and more preferably within the range of 3% to 20% of the axial gap C. The axial gap C preferably has a size of 0.05 mm to 3 mm, particularly 0.8 mm.

[0019] Preferably, the flexible sealing element of the lubricant chamber includes a first and a second flexible sealing element. Thus, the lubricant chamber is sealed by two flexible sealing elements, thereby preventing the generation of an inconvenient positive or negative pressure during displacement of the lubricant in the lubricant chamber, which inconvenient positive or negative pressure can, for example, exert an unintended force on the closing element of the gas injector via the components of the lubricant reservoir. By providing two flexible sealing elements, even if an inconvenient force is applied to one of the sealing elements, which can increase the pressure in the sealed lubricant chamber, an equilibrium can be provided by the second flexible sealing element. Thereby, an unwanted pressure change inside the sealed lubricant chamber can be successfully prevented.

[0020] More preferably, the reservoir spring applies a predetermined force from the outside to the lubricant in the sealed lubricant chamber. Here, a positive pressure between preferably 0.5 to 10×10 5 Pa, particularly preferably between 1 to 5×10 5 Pa is applied. Thereby, a predetermined pre-stress can be applied to the lubricant in the lubricant chamber, thereby reliably preventing unwanted deformations that may have an impact on the stroke of the closing element.

[0021] Particularly preferably, the first flexible sealing element is a first bellows and the second flexible sealing element is a second bellows. More preferably, the first and second bellows are identically formed, i.e., have the same average bellows diameter and the same bellows wave number. Thereby, in particular, the manufacturing cost of the gas injector can be reduced.

[0022] More preferably, the second bellows is connected to the reservoir spring via a spring receiver. Thereby, a simple and inexpensive structure can be realized. Furthermore, this allows a specific pre-stress to be directly applied to the second bellows by the reservoir spring, whereby the rigidity of the second bellows is slightly higher than that of the first bellows.

[0023] Alternatively, the first and second flexible sealing elements are a membrane and a rubber element respectively. The membrane may be single-layer or multi-layer, and may be fixed to the respective components by laser welding, for example, to seal the lubricant chamber.

[0024] Preferably, oil, especially mineral oil, is used as the lubricant. Alternatively, liquid fuel, especially diesel fuel or gasoline, is used. As a further alternative, grease is used as the lubricant.

[0025] Hereinafter, one exemplary embodiment of the present invention will be described in detail with reference to the accompanying drawings.

Brief Description of the Drawings

[0026]

Figure 1

Modes for Carrying Out the Invention

[0027] Hereinafter, with reference to FIG. 1, the gas injector 1 according to the first preferred exemplary embodiment of the present invention will be described in detail. As can be seen from FIG. 1, the gas injector 1 for introducing gaseous fuel includes a magnetic actuator 2 that moves a closing element 3 that opens to the outside from a closed state to an open state. Here, FIG. 1 shows the closed state of the gas injector.

[0028] The magnetic actuator 2 includes an armature 20 connected to the closing element 3 by an armature bolt 24. The magnetic actuator 2 further includes an inner pole 21, a coil 22, and a magnetic housing 23 that ensures magnetic feedback of the magnetic actuator.

[0029] Furthermore, the gas injector 1 includes a body 7 having a gas inlet 70 on its side surface, and gaseous fuel is supplied through the gas inlet 70 on the side surface. Here, a valve housing 8 is fixed to the body 7, and a magnetic actuator 2 is disposed within the valve housing 8. The valve housing 8 is connected to a housing sleeve 19 and a valve tube 90. At the free end of the valve tube 90, a sealing seat portion 11 is provided in a valve seat component 93. In this sealing seat portion 11, a closing element 3 releases and closes a passage for gaseous fuel.

[0030] FIG. 1 schematically shows an electrical connection portion 13 that is guided through the body 7 and the valve housing 8 to the magnetic actuator 2. Reference numeral 10 indicates a restoring element for returning the closing element 3 to the closed state shown in FIG. 1 after the opening process.

[0031] FIG. 1 further shows a gas flow as a gas path 14 through the gas injector 1. Here, the gas flow starts at the gas inlet 70, then is deflected and enters an annular space 80 between the valve housing 8 and the body 7. Here, the gas flow 14 passes through the outer region of the magnetic actuator 2, through a filter 15, and further proceeds to in front of the sealing seat portion 11. Here, corresponding openings are provided in each component, but not all of them are shown in FIG. 1.

[0032] When the gas injector 1 is opened, gaseous fuel flows through the outer circumference of the magnetic actuator 2 and the open sealing seat portion 11, as indicated by arrow A in FIG. 1, and into a nozzle attachment 94 and a combustion chamber 100 of an internal combustion engine.

[0033] The closing element 3 includes a valve needle 30 having a valve seat receiver 30a disposed at an end of the closing element facing the combustion chamber. Here, the sealing seat portion 11 is formed between the valve seat receiver 30a and a valve seat component 93 having a plurality of axial openings 92.

[0034] The closing element 3 is further provided with a fixed disk 30b which is arranged at a small distance from the valve seat receiver 30a in the direction of the magnetic actuator 2. Therefore, the closing element 3 releases and closes the gas passage 14 at the sealing seat portion 11. As can be seen in detail from FIG. 1, for guiding the closing element, a first needle guide portion 31 and a second needle guide portion 32 are provided between the closing element 3 and the guide sleeve 9. The first needle guide portion 31 is formed directly between the closing element 3 and the guide sleeve 9. The second needle guide portion 32 is formed between the spring receiver 16 and the guide sleeve 9. The spring receiver 16 is fixedly connected to the closing element 3, and the restoring element 10 is supported between the inner step portion 90a of the guide sleeve 9 and the spring receiver 16.

[0035] The gas injector 1 further includes a sealed lubricant chamber 4. The sealed lubricant chamber 4 is completely or partially filled with a liquid lubricant, such as oil. As can be seen from FIG. 1, the lubricant chamber 4 is defined by a first flexible sealing element 51, an inner magnetic pole 21, a magnetic housing 23, a guide body 18, and a second flexible sealing element 52. The first and second flexible sealing elements 51, 52 are each formed as bellows. Here, the first and second flexible sealing elements 51, 52 are formed in the same manner.

[0036] It should be noted that the flexible sealing elements 51, 52 may be, for example, a film or a tube instead of bellows. As can be further seen from FIG. 1, the second flexible sealing element 52 is fixed to the storage part spring receiver 41, for example, by a welded joint. The gas injector 1 further includes a storage part compression spring 40, which is supported by the main body 7 and applies a pre-stress to the second flexible sealing element 52 via the storage part spring receiver 41. The guide body 18 is provided with a connection hole 18a, whereby the lubricant in the lubricant chamber 4 also exists in the region inside the second flexible sealing element 52.

[0037] The first flexible sealing element 51 is directly fixed to the fixed disk 30b of the closing element 3 and is connected to the guide sleeve 9 at the other end. Here, the guide sleeve 9 is provided with a lateral hole 91, whereby there is a fluid connection between the internal space of the first flexible sealing element 51 and the internal space of the guide sleeve 9.

[0038] Accordingly, the lubricant chamber 4 has two flexible sealing elements 51, 52 and a storage compression spring 40. The storage compression spring 40 applies a specific pre-stress, for example 1×10 5 Pa, to the lubricant within the lubricant chamber 4. Thus, in the event of displacement of the lubricant due to the stroke of the closing element 3 during the opening process or further due to thermal expansion or cooling of the lubricant, the positive / negative pressure that may occur inside the lubricant chamber 4 can be balanced by the deflection of the second flexible sealing element 52 associated with the contraction of the storage compression spring 40. Thereby, there is no possibility that the flexible sealing element 51 applies an unintended force acting via the bellows working surface to the closing element 3.

[0039] Within the sealed lubricant chamber 4, there is also arranged an armature bolt 24 to which the armature 20 is fixed. Since the lubricant chamber 4 is filled with a lubricant, for example a liquid fuel such as gasoline or diesel fuel, or grease, the armature 20 is continuously lubricated. Thereby, the problems occurring in the prior art with gaseous fuels, namely that the moving parts are not lubricated, can be compensated for.

[0040] As can be seen from FIG. 1, a filling channel 17a is provided for filling the sealed lubricant chamber 4. The filling channel 17a is liquid-tightly closed by a closing ball 17.

[0041] As can be further understood from FIG. 1, here, a first needle guide portion 31 formed between the guide sleeve 9 and the valve needle 30 is disposed inside the first flexible sealing element 51. Further, a part of the restoring element 10 is also disposed inside the first flexible sealing element 51. A part of the guide sleeve 9 is also disposed inside the first flexible sealing element 51. That is, according to the present invention, the restoring element 10, the guide sleeve 9, and the first flexible sealing element 51 are disposed in a nested manner. Thereby, the axial structural length of the gas injector 1 can be significantly reduced.

[0042] Despite the valve needle 30, the restoring element 10, the guide sleeve 9, and the first flexible sealing element 51 being incorporated in a nested manner, the outer diameter is not increased, particularly in the region of the valve tube 90.

[0043] Furthermore, the storage part compression spring 40 and the storage part spring seat 41 are also disposed at least partially inside the second flexible sealing element 52. A region of the guide body 18 is also disposed inside the second flexible sealing element 52. Thereby, the axial structural length of the gas injector 1 is further reduced.

[0044] It should be noted that if the structural space ratio requires it, the nozzle attachment 94 may be eliminated. Further, the gaseous fuel is supplied laterally through the side gas inlet 70 and is not in the axial direction as was normal with gas injectors heretofore. This further reduces the structural length of the gas injector, particularly in the region of the gas injector that does not face the combustion chamber.

[0045] A braking mechanism 6 is further disposed in the sealed lubricant chamber 4. The braking mechanism 6 includes a brake bolt 60, a brake spring 61, and a damping chamber 62. The damping chamber 62 is in fluid connection with the lubricant chamber 4.

[0046] The brake bolt 60 and the elastic braking element 61 are operatively connected to the closing element 3 during the restoration process of the gas injector to the closed initial position. Here, during the restoration process, the lubricant is displaced from the damping chamber 62 to the lubricant chamber 4, so that additional damping is achieved when the brake bolt 60 is restored to the closed state of the gas injector (Figure 1). The brake bolt 60 is guided within the guide body 18.

[0047] As can be further seen from Figure 1, the damping chamber 62 is formed directly on the brake bolt 60 on the side that does not face the valve seat 11 of the brake bolt 60. The damping chamber 62 is connected to the connection hole 18a, and thus to the main region of the lubricant chamber 4, via a throttle portion 63 which is a small hole. The brake spring 61 is arranged in the spring chamber 67.

[0048] The brake bolt 60 has a contact surface 60a, and the contact surface 60a is in contact with the armature bolt 24. Here, in the closed state shown in Figure 1, there is a first gap 101 between the brake bolt 60 and the stationary armature bolt guide portion 25. The armature bolt guide portion 25 guides the armature bolt 24 during the opening process and the closing process.

[0049] As can be further seen from Figure 1, the brake spring 61 is arranged between the brake bolt 60 and the guide body 18. Here, the brake bolt 60 has a flange, and the flange is provided with play with respect to the guide body 18. Further, the guide body 18 is provided with a passage 65 which can be formed, for example, as a slit at the end of the guide body 18 facing the armature bolt guide portion 25. Thereby, a fluid connection for the lubricant can be provided from the spring chamber 67 through the guide play and the passage 65 to the lubricant chamber 4.

[0050] In the closed state, furthermore, a first gap 101 is formed between the contact surface 60a of the brake bolt 60 and the armature bolt guide part 25. Here, the gap 101 has a first width B, and the first width B is smaller than the second width C between the armature 20 and the inner pole 21 in the second gap 102 (see FIG. 1). Thereby, it is ensured that the stroke of the brake bolt 60, which is axially pre-stressed by the compression spring 61, is smaller than the stroke of the armature 20. Therefore, during the injection process, sufficient fluid can flow from the lubricant chamber 4 through the throttle part 63 into the damping chamber 62.

[0051] During the closing process, the armature bolt 24 hits the contact surface 60a of the brake bolt 60. Thereby, the brake bolt 60 is pushed toward the fluid in the damping chamber 62. The throttle part 63 enables the fluid to be slowly pushed out from the damping chamber 62 rather than immediately, thereby enabling a damping effect during the closing process. Thereby, the closing process is damped through the restoration of the brake bolt 60, preventing excessive wear of the sealing seat part 11 and the armature 20.

[0052] The damping process is further supported by the brake spring 61 and by the hydraulic adhesion of the brake bolt 60 in the armature bolt guide part 25. Here, in this region between the armature bolt guide part 25 and the contact surface 60a of the brake bolt 60, cavitation during the closing process can be prevented by the damping chamber 62. The friction of the brake bolt 60 in the guide body 18 also delays the restoration process. Furthermore, throughout the lubricant chamber 4, the mass that can accelerate the movable components displaces the lubricant in the sealed lubricant chamber 4, thereby causing further deceleration during the closing process.

[0053] By selecting the diameter and / or length of the throttle part 63, the damping behavior can be individually adjusted for each gas injector. It should be noted that preferably, the stopper surface between the damping bolt 60 and the armature bolt guide 25 can be formed in a wedge shape, that is, not perpendicular to the central axis X-X of the gas injector. Alternatively or in addition thereto, a radial slit can be provided on the contact surface 60a or on the end face of the armature bolt guide 25 facing the braking bolt 60, thereby further reducing and preventing the cavitation effect.

[0054] Here, the gas injector 1 shown in FIG. 1 is pressure-balanced. That is, the closing element 3 is connected to the guide sleeve 9 via the first flexible sealing element 51, and the first flexible sealing element 51 formed as a metal bellows has an average diameter equal to the diameter at the sealing seat 11, specifically the diameter at which the closing element 3 seals. Thereby, no compressive force is generated on the closing element 3, and thus the magnetic force required to open the closing element 3 can be kept very small, especially independent of the pressure of the gaseous fuel.

[0055] Therefore, according to the present invention, when the closing element 3 is opened by the operation of the magnetic actuator 2 (the leftward movement of the closing element 3 in FIG. 1) and gas injection is performed, reliable damping can be performed immediately before the closing element is pressed against the valve seat 11 when the closing element is restored. Here, the braking bolt 60 is pushed in the direction of the damping chamber 62 by the armature bolt 24 and moves only slowly, that is, as slowly as the lubricant is extruded from the damping chamber 62 through the throttle portion 63 into the lubricant chamber 4. Thereby, before the closing element hits the valve seat 11, the closing speed of the closing element 3 is effectively decelerated significantly. Thereby, the wear of the valve seat 11 and the closing element 3 can be effectively reduced, and here the braking mechanism 6 further enables a quieter operation of the gas injector. So-called closing impacts where the element hits the valve seat violently and rebounds can also be effectively prevented.

[0056] Since the sealing seat 11 is formed as a flat sealing seat, the sealing surfaces in the valve seat receiver 30a and the valve seat component 93 can be easily produced by flat machining such as polishing, for example.

[0057] Therefore, the gas injector 1 can provide reduced wear of moving parts, in particular the valve seat 11, the armature 20, and the armature bolts 24. Furthermore, heat dissipation from the magnetic actuator 2 can be significantly improved by the sealed lubricant chamber 4 containing a liquid lubricant. Additionally, both flexible sealing elements 51, 52 can prevent unintentional forces from acting on the closing element 3.

[0058] Furthermore, the gas injector 1 can have a significantly reduced axial length, and thus can be mounted laterally, in particular, to the combustion chamber 100 of an internal combustion engine. Since the components of the gas injector are nested and at the same time a lateral gas inlet 70 is provided, the axial structural length of the gas injector 1 is significantly reduced.

Claims

1. A magnetic actuator (2) having an armature (20), an inner pole (21), and a coil (22), A closing element (3) provided with a valve needle (30) for opening and closing a gas passage (14) at a sealing seat portion (11), wherein the armature (20) is connected to the closing element (3), the closing element (3), A sealed lubricant chamber (4) filled with a lubricant and having the armature (20) disposed therein, the lubricant chamber (4) for ensuring lubrication of the armature (20), A flexible sealing element (51) for sealing the lubricant chamber (4) against the gas passage (14), A restoring element (10) for returning the closing element (3) to its initial closed position, A gas injector for injecting gaseous fuel, including a first needle guide portion (31) formed between a guide sleeve (9) and the valve needle (30), The first needle guide portion (31) is disposed radially inside the flexible sealing element (51) within the lubricant chamber (4), The restoring element (10) is disposed at least partially inside the flexible sealing element (51) within the lubricant chamber (4), the gas injector.

2. The gas injector according to claim 1, wherein the flexible sealing element (51) is a bellows, or a membrane or a rubber element.

3. The gas injector according to claim 1 or 2, wherein the flexible sealing element (51) is directly fixed to the valve needle (30) and directly fixed to the guide sleeve (9).

4. The gas injector according to claim 3, wherein the valve needle (30) further has a fixing disk (30b), and the flexible sealing element (51) is fixed to the fixing disk (30b).

5. The gas injector according to any one of claims 1 to 4, further comprising a second needle guide part (32) formed between the valve needle (30) and the guide sleeve (9) within the lubricant chamber (4).

6. The gas injector according to any one of claims 1 to 5, wherein the restoring element (10) is entirely disposed within the guide sleeve (9).

7. The gas injector according to any one of claims 1 to 6, wherein the guide sleeve (9) has an inward-facing step portion (90a) for supporting the restoring element (10).

8. The gas injector according to any one of claims 1 to 7, further comprising a gas inlet (70) disposed on a side surface of the gas injector at an angle of 90° with respect to the longitudinal axis (X-X) of the gas injector.

9. The gas injector according to any one of claims 1 to 8, wherein the sealing seat portion (11) is a planar sealing seat portion.

10. A braking mechanism (6) is disposed within the lubricant chamber (4), and the braking mechanism (6) is configured to decelerate the closing element (3) during the restoring process of the gas injector from an open state to a closed state. The braking mechanism (6) has a braking bolt (60), a damping chamber (62) filled with lubricant and fluid-connected to the lubricant chamber (4), and an elastic braking element (61). The braking bolt (60) and the elastic braking element (61) can be operatively connected to the closing element (3) during the restoring process of the gas injector. The braking bolt (60) is configured to displace lubricant from the damping chamber (62) to the lubricant chamber (4) in order to damp the restoring of the braking bolt (60) to a closed state during the restoring process of the gas injector. The gas injector according to any one of claims 1 to 9.

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