Gas injector

Abstract

The present invention relates to a gas injector for injecting a gaseous fuel, comprising a magnetic actuator (2) with an armature (20), an inner pole (21) and a coil (22), a closing element (3) with a valve needle (31) and an armature pin (24), wherein the valve needle (31) opens and closes a gas path (14) at a sealing seat (11) arranged at a first end of the gas injector, wherein the armature (20) is connected to the armature pin (24) and the armature pin (24) is in operative communication with the valve needle (31), a sealed lubricant chamber (4) filled with a liquid (40) as a lubricant and a gas (41), in which the armature (20) and the armature pin (24) are arranged, wherein the lubricant provides a lubricating effect in the lubricant chamber (4), a return element (10) which returns the closing element (3) to the closed initial position, a Damping device (6),which is arranged in the lubricant chamber (4), wherein the damping device (6) is configured to dampen a closing movement of the closing element (3), a compensation chamber (5), which is part of the lubricant chamber (4) and in which liquid (40) and gas (41) are arranged, and an anti-mixing device (100), which is arranged in the compensation chamber (5) and is configured to prevent a mixing of liquid (40) and gas (41) in order to prevent foaming in the compensation chamber (5).

Description

State of the art

[0001] The present invention relates to a gas injector for injecting a gaseous medium, such as hydrogen, natural gas, methane, LPG, ammonia or the like, into a combustion chamber of an internal combustion engine with improved damping properties by means of a damper with very safe operating behavior.

[0002] Gas injectors are known in various designs from the prior art. Due to the relatively high gas pressures, a hard impact of a closing element, especially a valve needle, against a sealing seat occurs, particularly during the closing process. To avoid unnecessarily shortening the service life of the gas injector, damping devices should be provided. To avoid unnecessarily increasing manufacturing and maintenance costs, simple solutions are preferable. Disclosure of the invention

[0003] In contrast, the gas injector according to the invention for injecting a gaseous fuel, with the features of claim 1, has the advantage that simple and reliable damping of a closing element during the closing process of the gas injector is possible. This damping is ensured throughout the entire service life of the gas injector. The damping is also particularly robust and cost-effective, and thus suitable for mass production of gas injectors. Furthermore, the damping according to the invention requires only a very small installation space. The damping also prevents vibration excitation of other components of the gas injector during the closing process, so that the loads on these other components during operation can be significantly reduced. Furthermore, the measures according to the invention prevent foaming processes inside a lubricant chamber containing a liquid and a gas.This ensures a very stable function of the gas injector. Furthermore, it is also possible to arrange the gas injector not only vertically, i.e., with a central axis of the gas injector arranged vertically, but also in any inclined installation position. Thus, the gas injector according to the invention is suitable for use in internal combustion engines from various manufacturers, where the installation position may deviate slightly, particularly from a vertical axis.

[0004] According to the invention, this is achieved by the gas injector comprising a magnetic actuator with an armature, an inner pole, and a coil. Furthermore, the gas injector includes a closing element with a valve needle, wherein the closing element opens and closes a gas path at a first end of the gas injector at a sealing seat. This allows gas to be injected, for example, into a combustion chamber or terminates the injection. The closing element also includes an armature pin, which is connected to the armature and is operatively connected to the valve needle. The valve needle and the armature pin are preferably rod-like components that rest loosely against opposing end faces and are movable independently of each other. The gas injector further includes a lubricant chamber sealed by a lubricant housing, which is filled with a liquid lubricant and a gas.The anchor and anchor bolt are arranged in the lubricant chamber, with the lubricant providing lubrication for the components located therein. A return element returns the closing element to a closed initial position. The lubricant chamber is preferably designed as a sealed chamber by means of a flexible sealing element, in particular a bellows, the flexible sealing element being arranged on the closing element. The flexible sealing element seals the lubricant chamber against the injected gas via a gas path. Furthermore, the gas injector includes a damping device for dampening the closing action of the closing element, which is arranged in the lubricant chamber. The gas injector also includes a compensation chamber in which the liquid and the gas are arranged.The partially gas-filled lubricant chamber thus allows for simple volume expansion, particularly in the event of temperature-related volume changes in components and / or the fluid during operation. The compensation chamber is a sub-chamber of the lubricant chamber. During operation, the gas contained in the lubricant chamber is located in the compensation chamber of the gas injector. Furthermore, the gas injector includes an anti-mixing device, which is arranged in the compensation chamber and is designed to prevent the mixing of liquid and gas in the lubricant chamber. This prevents foaming, which could negatively affect the function of the gas injector.

[0005] The compensation chamber is preferably located at the end of the gas injector furthest from the sealing seat. If the gas injector is installed vertically or substantially vertically, the gas in the lubricant chamber collects in the compensation chamber at the end furthest from the lubricant chamber. The anti-mixing device located in the compensation chamber thus prevents foaming. Foaming must be avoided, in particular, to prevent gas droplets from entering the damping device and reducing the damping properties of the gas injector. This would lead to a shortened service life of the gas injector.

[0006] According to the invention, a separation between liquid and gas in the lubricant chamber can be achieved, even during operation. This makes the gas injector particularly suitable for installation at angles deviating from the vertical. Depending on the internal combustion engine from a particular manufacturer, the gas injector cannot always be installed in a perfectly vertical position. The gas injector according to the invention thus offers increased flexibility regarding installation positions and provides very robust and stable operation throughout its entire service life.

[0007] The dependent claims describe preferred embodiments of the invention.

[0008] The lubricant chamber is enclosed by the lubricant housing, which preferably comprises a plurality of components. The ratio of liquid, i.e., liquid lubricant, to gas in the lubricant chamber is preferably in the range of 70 / 30 vol.% to 95 / 5 vol.%. Particularly preferably, the liquid-to-gas ratio is in the range of 80 / 20 vol.% to 90 / 10 vol.%. Further preferably, the liquid-to-gas ratio in the lubricant chamber is approximately 85 to 15 vol.%.

[0009] The damping device preferably comprises a damping piston, a damping housing, a throttle, and a damping chamber formed within the damping housing. The throttle connects the damping chamber to the compensation chamber. A guide section is formed between the damping piston and the damping housing. This guides the damping piston within the damping housing. The guidance preferably extends over the entire axial length of the damping piston. The clearance between the damping piston and the damping housing is very small. The throttle is preferably located along the central axis of the gas injector. Due to the throttle, very high local flow velocities of the fluid in the lubricant chamber can occur during operation. These velocities are slowed down by the anti-mixing device according to the invention to prevent foaming.

[0010] Preferably, the throttle of the damping device is designed such that the throttle length in the axial direction of the gas injector is less than or equal to the throttle diameter. By selecting the throttle length and / or diameter, the throttle characteristics can thus be easily adjusted. In particular, this allows the flow rates of the liquid through the throttle to be adjusted, thereby setting the damping characteristics.

[0011] The damping chamber is preferably pot-shaped, and the choke is located at the bottom of the pot-shaped damping chamber. This allows for a particularly compact and simple design.

[0012] For a cost-effective design, the anti-mixing device preferably enables direct fluid communication between the liquid and the gas in the lubricant chamber. This allows the anti-mixing device to be designed very simply and cost-effectively, without the need for expensive specialized components such as membranes or similar. Thus, there is no rigid separation between the liquid and the gas in the lubricant chamber.

[0013] The anti-mixing device preferably comprises an intermediate component arranged in the compensation chamber. This intermediate component is thus positioned axially between the damping device and the end of the lubricant chamber furthest from the sealing seat. The intermediate component divides the compensation chamber into a first and a second sub-chamber, and has at least one connecting opening that links the first and second sub-chambers. In its installed position, the intermediate component is surrounded by fluid on both its inner and outer surfaces. In other words, the intermediate component is completely surrounded by fluid in its installed position. The connecting opening, which is preferably designed as a small-diameter bore, reduces any potentially high fluid flow velocity to prevent foaming of the fluid in the lubricant chamber during operation.

[0014] Alternatively, the anti-mixing device includes an intermediate component in the compensation chamber, which divides the compensation chamber into a first and a second sub-chamber. This intermediate component has a multitude of capillary connecting bores and is covered with liquid on both sides. The capillary connecting bores also provide only small cross-sectional areas between the first and second sub-chambers in the compensation chamber, thereby reducing flow velocities and thus the risk of foaming in the compensation chamber.

[0015] According to a further preferred alternative, the anti-mixing device comprises an intermediate component in the compensation chamber, which divides the compensation chamber into a first and a second sub-chamber, wherein the intermediate component has continuous connecting paths for connecting the first and second sub-chambers. The connecting paths are preferably undefined and can be provided, for example, by porous sections and / or mesh screens and / or steel wool inserts or the like. The continuous connecting paths have a very small maximum diameter, preferably less than 1 mm and particularly less than 0.5 mm.

[0016] According to a further alternative embodiment of the invention, the anti-mixing device comprises an intermediate component arranged in the compensation chamber, which has a chimney-like calming chamber for smoothing the flow of the liquid during operation. The chimney-like calming chamber of the intermediate component is directly connected to the damping device, so that during operation a liquid supplied at high velocity can be slowed down and calmed in the chimney-like calming chamber. The calming chamber is either open or closed to the compensation chamber. The chimney-like calming chamber is preferably located in the central axis of the gas injector. If the chimney-like calming chamber is closed to the compensation chamber, the intermediate component preferably has an annular base with at least one connecting bore to connect the damping device to the rest of the compensation chamber.If the chimney-like calming chamber is open to the equalization chamber, it may, for example, have porous areas, areas lined with steel mesh, areas filled with steel wool, or similar materials. Thus, the chimney-like calming chamber has fluid-permeable walls, thereby establishing a connection between the interior of the chimney-like calming chamber and the rest of the equalization chamber.

[0017] According to a further alternative of the present invention, the anti-mixing device in the compensation chamber comprises a first and a second inner diameter, which are different. The first inner diameter is directed towards the sealing seat and is smaller than the second inner diameter, which is formed in the region of the compensation chamber facing away from the sealing seat. The gas in the lubricant chamber is arranged in the region of the larger second inner diameter of the compensation chamber. The second inner diameter is preferably at least 1.5 times larger than the first inner diameter.

[0018] According to a further alternative embodiment of the invention, the anti-mixing device comprises a tube-like device which projects into the compensation chamber. The compensation chamber and the damping device are in fluid communication via the tube-like device. The tube-like device is preferably a hollow cylinder, in particular arranged in a central axis of the gas injector, or a curved tube or the like with a lateral intake opening.

[0019] According to a further preferred embodiment of the present invention, the anti-mixing device comprises a pressure-controlled valve. The pressure-controlled valve is configured to close a fluid connection between the compensation chamber and the damping device during the opening process of the gas injector and to open it during the closing process of the gas injector. The pressure-controlled valve is preferably a ball valve with a freely movable ball and two sealing seats.

[0020] Preferably, the anti-mixing device is designed such that direct fluid communication between the liquid and the gas is prevented. This ensures a clear separation between the gas and liquid, preventing foaming in the liquid during operation. The separating anti-mixing device is preferably a flexible element, in particular a flexible membrane, arranged in the compensation chamber, which separates the liquid from the gas in the compensation chamber. Alternatively, the flexible element is a gas-filled elastomer element containing a plurality of enclosed gas bubbles. The flexible element can also be pre-tensioned by means of spring elements. According to a further alternative for a separating anti-mixing device, it is preferably provided that the anti-mixing device comprises a piston arrangement with a movable piston that separates the gas and the liquid.The piston is preferably spring-loaded and is moved by pressure differences in the lubricant chamber.

[0021] The gas injector is preferably configured for the direct injection of a gas into the combustion chamber of an internal combustion engine. The gas injector is preferably an outwardly opening gas injector. Brief description of the drawings

[0022] Preferred embodiments of the invention are described in detail below with reference to the accompanying drawing. The drawing shows: Fig. 1 a schematic sectional view of a gas injector according to a first preferred embodiment of the invention, Fig. 2 an enlarged partial sectional view of a damping device and a compensation chamber of the gas injector of Fig. 1, Fig. 3 a partial sectional view of a gas injector according to a second embodiment of the invention, Fig. 4 a partial sectional view of a gas injector according to a third embodiment of the invention, Fig. 5 a partial sectional view of a gas injector according to a fourth embodiment of the invention, Fig. 6 a partial sectional view of a gas injector according to a fifth embodiment of the invention, Fig. 7 a partial sectional view of a gas injector according to a sixth embodiment of the invention, Fig. 8 a partial sectional view of a gas injector according to a seventh embodiment of the invention, Fig. 9 a partial sectional view of a gas injector according to an eighth embodiment in a vertical installation position, Fig. 10 a partial sectional view of the gas injector of Fig. 9 in an angled installation position, Fig. 11 a partial sectional view of a gas injector according to a ninth embodiment in a vertical installation position, Fig. 12 a partial sectional view of the gas injector of Fig. 11 in an angled installation position, Fig. 13 a partial sectional view of a gas injector according to a tenth embodiment of the invention, Fig. 14 a partial sectional view of a gas injector according to an eleventh embodiment of the invention, Fig. 15 a partial sectional view of a gas injector according to a twelfth embodiment of the invention, and Fig. 16 a partial sectional view of a gas injector according to a thirteenth embodiment of the invention. Preferred embodiments of the invention

[0023] The following refers to the Fig. 1 and Fig. 2 a gas injector 1 according to a first preferred embodiment of the invention is described in detail.

[0024] Fig. Figure 1 shows the closed state of gas injector 1.

[0025] As from Fig. As can be seen in Figure 1, the gas injector 1 for injecting a gaseous fuel into a combustion chamber 30 comprises a magnetic actuator 2. The magnetic actuator 2 moves a closing element 3, which in this embodiment is an outwardly opening valve needle, from a closed state to an open state.

[0026] The magnetic actuator 2 comprises an armature 20, which rests against the closing element 3 by means of an armature bolt 24. Furthermore, the magnetic actuator 2 comprises an inner pole 21, a coil 22, and a magnetic housing 23, which ensures a magnetic return of the magnetic actuator.

[0027] The gas injector 1 further comprises a main body 7 with a connection area 70, through which the gaseous fuel is supplied into an inner region of the gas injector. A valve housing 8 is fixed to the main body 7, to which a housing sleeve 19 and a valve tube 90 are connected in the axial direction XX of the gas injector. A sealing seat 11 is provided at the free end of the valve tube 90.

[0028] The closing element 3 either opens or closes a passage for the injection of the gaseous fuel.

[0029] In Fig. Figure 1 schematically shows an electrical connection 13, which is led through the main body 7 to the magnetic actuator 2.

[0030] The locking element 3 is inserted into the Fig. 1. The closed position shown is a return from the open position. Fig. Figure 1 schematically indicates a gas path 14 by the arrows in the gas injector. The gas path is essentially routed around the internal components of the gas injector. Accordingly, openings are arranged in the components of the gas injector.

[0031] The gas injector 1 further comprises a sealed lubricant chamber 4, which is filled with a liquid 40 as a lubricant, preferably oil, and a gas 41, preferably air. As shown from Fig. As can be seen in Figure 1, the lubricant chamber 4 is defined by a bellows 51, which is fixed to the closing element 3, a sleeve 52, the inner pole 21, a damping housing 60, and a compensation chamber 5. The compensation chamber 5 is located at the end of the lubricant chamber 4 furthest from the sealing seat 11.

[0032] The gas injector 1 is shown in a vertical installation position. The axial direction XX is vertically aligned. This ensures that the gas 41 collects in the compensation chamber 5. Fig. 1 and Fig. 2 is a schematic representation of a dividing line 43 between gas 41 and liquid 40.

[0033] Most of the lubricant chamber 4 is filled with the liquid lubricant.

[0034] This ensures, in particular, lubrication of the armature 20 during operation. The return element 10 is also located in the lubricant chamber.

[0035] Furthermore, the gas injector 1 comprises a damping device 6, which is arranged in the lubricant chamber 4. The damping device 6 is arranged axially from the sealing seat towards the armature 20.

[0036] The damping device 6 is described in detail on Fig. 2 is evident.

[0037] The damping device 6 comprises a damping piston 61, the damping housing 60, a throttle 62 and a damping chamber 63 arranged in the damping housing 60. The damping chamber 63 is pot-shaped, with the damping piston 61 being partially arranged in the damping chamber.

[0038] The damping piston 61 is cylindrical and has a through-opening 64 which runs in a central axis of the gas injector.

[0039] The damping device 6 further comprises a return element 65 for returning the damping piston 61 to its position. Fig. 2 Starting positions shown.

[0040] As from Fig. As can be seen in Figure 2, the end face 24a of the anchor bolt 24, facing away from the sealing seat, is in direct contact with an end face 61b of the damping piston 61. The anchor bolt 24 is guided in a stationary guide component 25. In the closed state of the gas injector, a gap 26 exists between the end face of the damping piston 61 facing the sealing seat and the guide component 25. The return element 65 is pre-tensioned and is supported between a flange 61a of the damping piston 60 and the damping housing 60.

[0041] The gas injector 1 further comprises an anti-mixing device 100. The anti-mixing device 100 is arranged in the compensation chamber 5. This divides the compensation chamber into a first subchamber 5a and a second subchamber 5b. The first subchamber 5a is completely filled with liquid, and the second subchamber 5b is partially filled with liquid and partially with gas.

[0042] The anti-mixing device 100 comprises an intermediate component 101 with several connecting openings 102. The connecting openings 102 serve for fluid connection between the first sub-chamber 5a and the second sub-chamber 5b. The connecting openings 102 are preferably small bores.

[0043] As especially from Fig. As can be seen in Figure 2, the intermediate component 101 is thus covered with liquid on both an inner surface 101a and an outer surface 101b. In other words, the intermediate component 101 is completely immersed in the liquid in the lubricant chamber 4.

[0044] The anti-mixing device 100 is designed to prevent the mixing of gas and liquid in the compensation chamber 5 as far as possible, in particular to prevent foam formation during operation. Foam formation during operation poses a significant risk to the function of the gas injector and especially to the function of the damping device 6. Should gas bubbles enter the area of ​​the damping device 6, there is a risk that the damping device 6 will no longer provide adequate damping for the opening and closing process of the closing element. In particular, this can lead to time delays and inconsistent damping functions, so that during operation the closing element may be damaged by a strong impact on the sealing seat 11.

[0045] The function of the gas injector according to the invention is as follows. When the gas injector is to be opened, the magnetic actuator 2 is energized, thereby pulling the armature 20, which is rigidly connected to the armature bolt 24, towards the inner pole 21. Since the armature bolt 24 is in direct contact with the closing element 3, this lifts the closing element 3 from the sealing seat 11, allowing gas to be injected into the combustion chamber 30.

[0046] In the damping device 6, the spring force of the return element 65 moves the damping piston 61 towards the guide component 25, which in Fig. 2 is indicated by arrow A. This overcomes the gap 26 and increases the volume of the damping chamber 63. Lubricant can flow into the damping chamber 63 either through the throttle 62 or through the through-opening 64.

[0047] When the gas injector closes, the current to the magnetic actuator 2 is terminated, causing the reset element 10 to return the closing element 3 and the armature bolt 24 to their closed positions. In doing so, the armature bolt 24 comes into contact with the end face 61b of the damping piston 61 and moves it in the opposite direction to the opening direction A.

[0048] Since there is only a very narrow guide gap 6a between the damping piston 61 and the damping housing 60 at a guide area 66, the damping piston 60 must be reset by displacing this fluid from the damping chamber 63. Because the guide gap 6a is very narrow in the guide area 66, this displacement occurs essentially exclusively via the throttle 62 into the compensation chamber 5.

[0049] Thus, fluid exits the throttle 62 at high speed into the first sub-chamber 5a of the compensation chamber 5, which in Fig. 2 is represented by the arrows B. Without the anti-mixing device, a very strong flow would therefore be generated at the liquid surface in the compensation chamber 5 due to liquid entering at high speed, which could lead to foaming.

[0050] The anti-mixing device 100 according to the invention, with the intermediate component 101 in the compensation chamber 5, prevents a direct flow of the accelerated liquid. The accelerated liquid strikes the inner surface 101a of the intermediate component 100 and is significantly slowed down. Since the connecting openings 102 have very small diameters, it is prevented that rapidly flowing liquid enters the second sub-chamber 5b of the compensation chamber 5. This prevents the formation of foam during operation. Consequently, there is also no risk of gas bubbles entering the area of ​​the damping device 6 and, in particular, the area of ​​the throttle or the damping chamber 63.

[0051] Since the dimensions of the throttle 62 can be manufactured very precisely, in addition to precise damping of the closing element 3 via the anchor bolt and the damping piston 61, it is also possible to adjust the velocity of the fluid exiting the throttle. In particular, throttling is independent of the axial length of the guide section 66 between the damping piston 61 and the damping housing 60.

[0052] Further embodiments of the invention are described in detail below, wherein identical components are designated with the same reference numerals as in the first embodiment.

[0053] Fig. Figure 3 shows a gas injector 1 according to a second embodiment of the invention. The anti-mixing device 100 of the second embodiment comprises an intermediate component 101 with a plurality of capillary connecting bores 103. As shown in Fig. As shown in Figure 3, a multitude of capillaries are provided to connect the first subspace 5a with the second subspace 5b. The capillary connecting bores 103 effectively prevent gas bubbles from reaching the damping device 6.

[0054] Fig. Figure 4 shows a third embodiment, wherein the anti-mixing device 100 has an intermediate component 101 with integrated, continuous connecting paths. This is shown in the embodiment of Fig. 4. The continuous connection paths with a very small maximum cross-section, in particular less than 1 mm, preferably less than 0.5 mm, can also be provided by porous component areas and / or mesh screens or the like.

[0055] The in Fig. Figure 5, the fourth embodiment, shows an intermediate component 101 with a chimney-like settling chamber 105. The chimney-like settling chamber 105 is provided within a hollow cylinder 106. The hollow cylinder 106 lies on the central axis, in which the throttle 62 is also located. A high-velocity liquid exiting the throttle 62 (arrow B) enters the chimney-like settling chamber 105 and is thereby decelerated. The hollow cylinder 106 has an end 106a facing away from the sealing seat, which is rigidly connected to the bottom of the equalization chamber 5. A connection between the first sub-chamber 5a and the second sub-chamber 5b is established via through-openings 108, which are provided in a base 107 that is flange-like around the hollow cylinder 106. Thus, the hollow cylinder 106 provides radial separation between the gas and liquid in the equalization chamber 5.

[0056] Fig. Figure 6 shows a gas injector 1 according to a fifth embodiment of the invention. In the fifth embodiment, the anti-mixing device 100 has an intermediate component 101, which is designed as a hollow cylinder 106. A free end 106a of the hollow cylinder 106 extends into the area of ​​the compensation chamber 5, in which the gas 41 is located. A liquid exiting the hollow cylinder 106 at high acceleration is deflected and slowed down at the bottom of the compensation chamber 5. The liquid then drips from the bottom of the compensation chamber 5 into the liquid-filled area of ​​the compensation chamber 5 without excessive foaming.

[0057] Fig. Figure 7 shows a gas injector according to a sixth embodiment of the invention. This sixth embodiment has a hollow cylinder 109 with radial wall openings 109a. The hollow cylinder 109 extends from the damping device 6 to the bottom of the compensation chamber 5. The hollow cylinder 109 again has a chimney-like calming chamber in which the velocity of the liquid is reduced, and a further reduction in velocity can occur when the liquid passes through the wall openings of the hollow cylinder 109. Preferably, additional obstacles, for example steel wool 104 or the like, are provided in the chimney-like calming chamber of the hollow cylinder 109, or the hollow cylinder is made of a porous material.

[0058] At the in Fig. In the seventh embodiment shown in Figure 8, the gas injector 1 has an anti-mixing device 100 which has two different inner diameters at the compensation chamber 5. A first inner diameter D1 defines the area in the compensation chamber 5 where the liquid 40 is located. A second inner diameter D2 in the compensation chamber 5 is the area where the gas 41 is located. The second diameter D2 is larger than the first diameter D1, preferably by a factor of 1.5 or more. Thus, the gas bubble is located in an area with a large radial space. The gas bubble is sufficiently far from the throttle of the damping device 6 so that liquid supplied at high velocity can be slowed down by the liquid located in the compensation chamber 5.

[0059] The Fig. 9 and Fig. Figure 10 shows a gas injector according to an eighth embodiment of the invention, wherein the Fig. 9 represents a vertical installation position and the Fig. Figure 10 shows an angled installation position at an angle of approximately 45°. The anti-mixing device 100 comprises a tubular device 110. The tubular device 110 is designed as a hollow cylinder and is arranged in a central axis of the gas injector. One end of the tubular device 110 is slightly conical. The tubular device 110 terminates as shown in Figure 10. Fig. Figure 9 shows the vertical arrangement within the liquid region in the compensation chamber 5. The inner diameter of the tubular device 110 is significantly larger than the inner diameter of the throttle. This results in initial settling of high-velocity liquid within the tubular device 110. The axial length of the tubular device 110 is selected such that, in every installation position, a free end of the tubular device 110 lies within the liquid region. This is shown schematically in Figure 9. Fig. Figure 10 shows an angled installation position at approximately 45°. A free end of the tubular device 110 is still located below the dividing line 43 (liquid surface) between gas 41 and liquid 40.

[0060] The Fig. 11 and Fig. Figure 12 shows a ninth embodiment of the invention, which is similar to the eighth embodiment. Fig. Figure 11 shows a vertical installation position of the gas injector and Fig. Figure 12 shows an angled installation position at approximately 45°. In contrast to the eighth embodiment, in the ninth embodiment the tubular device 110 is designed such that an outlet area 110a is provided laterally on the tubular device 110. This causes the tubular device 110 to have a deflection, in particular a deflection of 90° onto an inner shell region of the compensation chamber 5, thus enabling further flow stabilization within the tubular device 110. This further reduces the risk of foam formation during operation.

[0061] Fig. Figure 13 shows a gas injector with an anti-mixing device 100 according to a tenth embodiment of the invention. The anti-mixing device 100 comprises a valve 111. The valve 111 includes a ball 112 which seals against a sealing seat 113. The ball 112 is arranged with clearance 114 in a housing 115 of the valve 111. The valve 111 is pressure-controlled and opens during the closing process of the gas injector. Lateral openings are provided in the housing 115 so that the liquid can flow from the valve 111 into the compensation chamber 5.

[0062] Fig. Figure 14 shows a gas injector according to an eleventh embodiment of the invention. The gas injector of the eleventh embodiment has an anti-mixing device 100 with a diaphragm 116. The diaphragm 116 ensures a fluid-tight seal between the liquid-filled area and the gas-filled area in the compensation chamber 5. Thus, the anti-mixing device 100 of the eleventh embodiment is designed to prevent direct fluid communication between the gas 41 and the liquid 40. This reliably prevents foam formation.

[0063] Fig. Figure 15 shows a gas injector with an anti-mixing device 100 according to a twelfth embodiment of the invention. The anti-mixing device 100 comprises an elastomer 120 with enclosed gas bubbles 41. This makes it possible for temperature-related volume changes of the liquid 40 to be easily compensated for by deformation of the elastomer 120. The anti-mixing device 10 of the twelfth embodiment thus again ensures complete fluid separation between gas and liquid in the lubricant chamber. It should be noted that instead of enclosed gas bubbles, a type of porous, flexible sponge or the like can also be provided in the elastomer material, so that a connection between gas and liquid is theoretically possible. When the liquid expands, liquid can then also penetrate the sponge-like elastomer 120.

[0064] Fig.Figure 16 shows a gas injector 1 according to a thirteenth embodiment of the invention. The gas injector 1 comprises an anti-mixing device 100, which includes a piston assembly 130. The piston assembly 130 comprises a piston 131 axially pre-tensioned by a spring 132. The piston 131 provides complete separation between the liquid 40 and the gas 41. When the liquid 40 expands due to temperature, the piston 131 is moved in the axial direction XX. Return to its original position upon cooling is effected by the spring 132. Thus, the thirteenth embodiment also shows an anti-mixing device that provides complete fluid separation between the gas and the liquid.

[0065] It should be noted that for all embodiments, it is also possible that any combination of the illustrated embodiments is obvious to a person skilled in the art.

Claims

[1] Gas injector for injecting a gaseous fuel, comprising: - a magnetic actuator (2) with an armature (20), an inner pole (21) and a coil (22), - a closing element (3) with a valve needle (31) and an armature bolt (24), wherein the valve needle (31) opens and closes a gas path (14) at a sealing seat (11) arranged at a first end of the gas injector, wherein the armature (20) is connected to the armature bolt (24) and the armature bolt (24) is operatively connected to the valve needle (31), - a closed lubricant chamber (4) which is filled with a liquid (40) as lubricant and a gas (41), and in which the armature (20) and the armature bolt (24) are arranged, wherein the lubricant provides a lubricating effect in the lubricant chamber (4), - a return element (10) which returns the closing element (3) to the closed initial position, - a damping device (6) arranged in the lubricant chamber (4), wherein the damping device (6) is designed to dampen a closing movement of the closing element (3), - a compensation chamber (5), which is part of the lubricant chamber (4) and in which liquid (40) and gas (41) are arranged, and - an anti-mixing device (100) which is arranged in the compensation chamber (5) and is designed to prevent mixing of liquid (40) and gas (41) in order to prevent foam formation in the compensation chamber (5). [2] Gas injector according to claim 1, wherein the anti-mixing device (100) enables direct fluid communication between the liquid (40) and the gas (41) in the compensation chamber (5). [3] Gas injector according to claim 2, wherein the anti-mixing device (100) comprises an intermediate component (101) which is arranged in the compensation chamber (5), wherein the intermediate component (101) has at least one connection opening and divides the compensation chamber (5) into a first sub-chamber (5a) and a second sub-chamber (5b), wherein the intermediate component (101) is completely covered with liquid (40). [4] Gas injector according to claim 2, wherein the anti-mixing device (100) comprises an intermediate component (101) which is arranged in the compensation chamber (5), wherein the intermediate component (101) divides the compensation chamber (5) into a first sub-chamber (5a) and a second sub-chamber (5b), wherein the intermediate component (101) comprises a plurality of capillary connecting bores (103) which connect the first sub-chamber (5a) to the second sub-chamber (5b). [5] Gas injector according to claim 2, wherein the anti-mixing device (100) comprises an intermediate component (101) which is arranged in the compensation chamber (5), wherein the intermediate component (101) divides the compensation chamber (5) into a first sub-chamber (5a) and a second sub-chamber (5b), wherein the intermediate component (101) has continuous connecting paths and is designed in particular as a porous component and / or as a sieve mesh and / or as a region comprising steel wool. [6] Gas injector according to claim 2, wherein the anti-mixing device (100) comprises an intermediate component (101) arranged in the compensation chamber (5), wherein the intermediate component (101) has a component with a chimney-like calming chamber (105) for calming the flow of the liquid supplied from the damping device (6), wherein a fluid connection is present between the calming chamber (105) and the compensation chamber (5) or there is no fluid connection between the calming chamber (105) and the compensation chamber (5). [7] Gas injector according to claim 6, wherein the chimney-like calming chamber (105) is formed in a hollow cylindrical component. [8] Gas injector according to claim 2, wherein the anti-mixing device (100) is integrated into the compensation chamber (5), wherein the compensation chamber (5) has a region filled with gas (41) and a region filled with liquid (40), wherein a first inner diameter (D1) in the region filled with liquid (40) is smaller than a second inner diameter (D2) in the region filled with gas (41). [9] Gas injector according to claim 2, wherein the anti-mixing device (100) comprises a tubular device (110), in particular a hollow cylinder arranged in the central axis of the gas injector or a bent tube with a lateral opening, wherein the tubular device (110) projects into the compensation chamber (5) and a free end of the tubular device (110) is covered with liquid. [10] Gas injector according to claim 2, wherein the anti-mixing device (100) comprises an intermediate component (110) which is arranged in the compensation chamber (5), wherein the intermediate component (110) comprises a pressure-controlled valve (111) which is designed to close a fluid connection between the compensation chamber (5) and the damping device (6) during an opening process of the gas injector and to open it during a closing process of the gas injector. [11] Gas injector according to claim 10, wherein the pressure-controlled valve is a ball valve with a limited freely movable ball, wherein the ball closes the valve at a sealing seat during the opening process of the gas injector. [12] A gas injector according to claim 1, wherein the anti-mixing device (100) prevents direct fluid communication between the gas (41) and the liquid (40). [13] Gas injector according to claim 12, wherein the anti-mixing device (100) is a flexible element arranged in the compensation chamber (5), in particular a flexible membrane or an elastomer element filled with gas (41). [14] Gas injector according to claim 12, wherein the anti-mixing device (100) comprises a piston assembly (130) with a movable piston (131), the movable piston (131) separating the liquid (40) and the gas (41) in a fluid-tight manner.

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