Gas injector

Abstract

The present invention relates to a gas injector for injecting a gaseous fuel, comprising: a magnetic actuator having an armature, an inner pole, and a coil; a closing element having a valve needle and an armature bolt, the valve needle opening and closing a gas path at a sealing seat arranged at a first end of the gas injector, the armature being connected to the armature bolt and the armature bolt being operatively connected to the valve needle; a sealed lubricant chamber which is filled with a liquid acting as a lubricant and in which the armature and the armature bolt are arranged, the lubricant providing a lubricating effect in the lubricant chamber; a return element which returns the closing element to the closed initial position; a damping device which is arranged in the lubricant chamber, the damping device being designed to damp a closing movement of the closing element; and a compensation chamber which forms part of the lubricant chamber and in which liquid is present, wherein at least one component of the lubricant chamber is an additively manufactured component which is manufactured by means of an additive manufacturing process.

Description

[0001] R.414681

[0002] - 1 -

[0003] Description

[0004] title

[0005] State of the art

[0006] 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.

[0007] 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 a 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.

[0008] Disclosure of the invention

[0009] 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 is possible during the closing process of the gas injector. This damping is ensured over 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 R.414681 during the closing process.

[0010] - 2 -

[0011] The gas injector is designed so that the stress on 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 very stable operation of the gas injector. 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.

[0012] 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 each other at opposite 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.The anchor and anchor bolt are arranged in the lubricant chamber, with the lubricant providing lubrication for the components located in the lubricant chamber. 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, wherein the flexible sealing element is arranged on the closing element. The flexible sealing element seals the lubricant chamber against the injected gas at a passing gas path. Furthermore, the gas injector includes a damping device for damping 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 is arranged. The liquid-filled R.414681.

[0013] - 3 -

[0014] The lubrication chamber thus enables, in particular, a simple

[0015] The expansion chamber provides a buffer against temperature-related volume changes in components and / or the fluid during operation. It is a sub-chamber of the lubricant chamber. One component of the lubricant chamber is an additive component manufactured using an additive process. Preferably, the additive component is made of metal or a metal-containing composite material.

[0016] The additive component preferably has at least one undercut or other complex contours. This opens up new design possibilities for layout and manufacturing, thus enabling the optimization of components in the lubricant chamber.

[0017] The components of the lubricant chamber are preferably housing components and / or components arranged within the lubricant chamber itself. Furthermore, the use of additive components eliminates certain joining points, such as welds and / or press fits, as well as deburring and drilling operations during manufacturing. This also simplifies assembly.

[0018] Furthermore, the use of additive components enables optimal use of installation space and, in particular, a reduction in injector length. This allows customer-specific requirements for a gas injector to be met in a simple manner.

[0019] The dependent claims describe preferred embodiments of the invention.

[0020] Preferably, the lubrication chamber is filled with a liquid lubricant and a gas. The fact that the lubrication chamber is only partially filled with liquid allows for simple volume expansion, particularly if temperature-related volume changes of components and / or the liquid occur during operation of the gas injector.

[0021] The additive component is particularly preferably a separator arranged in the compensation chamber. Especially when the compensation chamber is filled with liquid and gas, the separator serves to prevent gas from entering the R.414681

[0022] - 4 -

[0023] The separator prevents the passage of fluid, especially hydraulic oil. In a lubrication chamber filled only with liquid, the separator also serves to reduce the flow velocity of the fluid within the lubrication chamber during opening and / or closing operations.

[0024] Preferably, the separator, manufactured as an additive component, comprises a porous area with continuous pores. These continuous pores connect a side facing the damping device with an opposite side of the separator. Such pores can be produced particularly easily and cost-effectively using additive manufacturing processes. The porous area of ​​the separator serves, in particular, to disperse a liquid jet while simultaneously reducing the liquid's kinetic energy. Especially during the closing of the gas injector, the liquid can reach a high velocity after flowing through a throttle of the damping device. This can lead to foaming and the introduction of gas bubbles into the liquid, especially if gas is present in the compensation chamber. The separator with the porous area can significantly reduce and prevent this.

[0025] Preferably, the separator includes a section with undercut channels. These undercut channels also serve to reduce the kinetic energy of the fluid in the lubricant chamber. Additive manufacturing allows for a variety of channel geometries to be incorporated to calm the fluid within the separator. Particularly preferably, the separator includes a spiral section with a helical channel that connects a side of the separator facing the damping device to an opposite side. When the fluid flows back from the damping device, it must pass through the helical channel, effectively reducing its kinetic energy.

[0026] The pores of the porous area of ​​the separator preferably have a diameter in the range of 20 pm to 60 pm, more preferably 30 pm to 50 pm and particularly 40 pm.

[0027] Preferably, the separator is formed as a single unit with a housing component of the lubricant chamber. This reduces the number of parts of the gas injector R.414681.

[0028] - 5 - can be reduced. Assembly of the lubricant compartment can also be simplified.

[0029] Particularly preferred are the separator, a housing of the compensation chamber and a damping housing of the damping device, a one-piece additive component.

[0030] Furthermore, the gas injector is 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 with regard to installation positions and provides very robust and stable operation throughout its entire service life.

[0031] 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.%.

[0032] 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. During operation, the throttle allows for very high local flow velocities of the fluid in the lubricant chamber, which are slowed down by the separator to prevent foaming. R.414681

[0033] - 6 -

[0034] 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.

[0035] 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.

[0036] The separator preferably divides the compensation chamber into a first and a second sub-chamber, wherein the separator is preferably covered with liquid on both sides. This reduces flow velocities and thus the risk of foaming in the compensation chamber.

[0037] The gas injector is preferably configured for the direct injection of gas into the combustion chamber of an internal combustion engine or for intake manifold injection. The gas injector is preferably an outwardly opening gas injector.

[0038] Brief description of the drawings

[0039] Preferred embodiments of the invention are described in detail below with reference to the accompanying drawing. The drawing shows:

[0040] Figure 1 shows a schematic sectional view of a gas injector according to a first preferred embodiment of the invention.

[0041] Figure 2 shows an enlarged partial sectional view of a damping device and a compensation chamber of the gas injector of Figure 1.

[0042] Figure 3 shows a partial sectional view of a gas injector according to a second embodiment of the invention, R.414681

[0043] - 7 -

[0044] Figure 4 shows a partial sectional view of a gas injector according to a third

[0045] Exemplary embodiment of the invention,

[0046] Figure 5 shows a partial sectional view of a gas injector according to a fourth

[0047] Exemplary embodiment of the invention, and

[0048] Figures 6 to 8 show further embodiments of the invention.

[0049] Preferred embodiments of the invention

[0050] A gas injector 1 according to a first preferred embodiment of the invention is described in detail below with reference to Figures 1 and 2.

[0051] Figure 1 shows the closed state of gas injector 1.

[0052] As can be seen from 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.

[0053] 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.

[0054] 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.

[0055] The closing element 3 opens or closes a passage at the sealing seat 11 for the injection of the gaseous fuel. R.414681

[0056] - 8 -

[0057] Figure 1 schematically shows an electrical connection 13, which is led through the main body 7 to the magnetic actuator 2.

[0058] The closing element 3 is returned from the open position to the closed position shown in Figure 1 by means of a return element 10. In Figure 1, a gas path 14 is schematically indicated 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.

[0059] 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 can be seen from Figure 1, the lubricant chamber 4 is formed 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 arranged at the end of the lubricant chamber 4 facing away from the sealing seat 11.

[0060] The gas injector 1 is shown in a vertical installation position. The axial direction XX is vertically oriented. This ensures that the gas 41 collects in the compensation chamber 5. In Figures 1 and 2, a dividing line 43 between gas 41 and liquid 40 is shown schematically.

[0061] Most of the lubricant chamber 4 is filled with the liquid lubricant.

[0062] This ensures, in particular, lubrication of the armature 20 during operation. The return element 10 is also located in the lubricant chamber.

[0063] 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.

[0064] The damping device 6 is shown in detail in Figure 2. R.414681

[0065] - 9 -

[0066] 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.

[0067] The damping piston 61 is cylindrical and has a through-opening 64 which runs in a central axis of the gas injector.

[0068] The damping device 6 further comprises a return element 65 for returning the damping piston 61 to the initial position shown in Figure 2.

[0069] As can be seen in Figure 2, an 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 61 and the damping housing 60.

[0070] The gas injector 1 further comprises a separator 100. The separator 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.

[0071] The separator 100 is an additive component and is designed to prevent the mixing of liquid 40 and gas 41 in the compensation chamber 5.

[0072] The separator 100 has a porous area 101, which is formed with a multitude of through pores. The porous area can be produced particularly easily by an additive manufacturing process. As can be seen from Figure 2, the separator 100 is formed in one piece with a housing 50 of the compensation chamber 5. The housing 50 is without pores. R.414681

[0073] - 10 - designed to prevent gas and liquid from escaping from the compensation chamber 5.

[0074] Figure 2 schematically shows pores 102.

[0075] As can be seen particularly from Figure 2, the separator 100 is thus covered with liquid on both an inner surface 101a and an outer surface 101b. In other words, the separator 100 is completely immersed in the liquid in the lubricant chamber 4.

[0076] The separator 100 is designed to prevent the mixing of gas and liquid in the compensation chamber 5 as much 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.

[0077] 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.

[0078] In the damping device 6, the spring force of the return element 65 moves the damping piston 61 towards the guide component 25, as indicated by arrow A in Figure 2. This overcomes the gap 26 and increases the volume of the damping chamber 63. Lubricant can flow into the damping chamber 63 via the throttle 62 and also via the through-opening 64. R.414681

[0079] - 11 -

[0080] When the gas injector closes, the current to the magnetic actuator 2 is terminated, so that the reset element 10 returns the closing element 3 and the armature bolt 24 to their closed position. In doing so, the armature bolt 24 comes into contact with the end face 61 b ​​of the damping piston 61 and moves it in the opposite direction to the opening direction A.

[0081] 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 61 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.

[0082] Thus, liquid exits the throttle 62 at high velocity into the first subchamber 5a of the equalization chamber 5, as indicated by arrows B in Figure 2. Since the separator 100 has the porous region 101, the high-velocity liquid exiting the throttle encounters the porous region 101 and penetrates the pores 102. The kinetic energy of the liquid is dissipated in the pores, so that when the liquid exits through the continuous pores 102 in the separator 100, it has only a low velocity on the outer surface 101b. This prevents a very strong flow at the liquid surface in the equalization chamber 5, thus significantly reducing the risk of foaming and the absorption of gas bubbles into the liquid.

[0083] The one-piece design of the separator 100 with the housing 50 of the compensation chamber 5 significantly reduces the number of parts and the number of necessary assembly operations. Depending on the design of the expected velocities on the underside 101a of the separator 100, the thickness of the separator 100 in the axial direction can be increased, thus providing a means of slowing down the flowing fluid. Furthermore, joining and deburring operations on the components are eliminated. The axial length of the gas injector can also be reduced, and the installation space of the lubricant reservoir inside the gas injector can be optimized. R.414681

[0084] - 12 -

[0085] Therefore, there is 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.

[0086] 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.

[0087] 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.

[0088] Figure 3 shows a gas injector 1 according to a second embodiment of the invention. The separator 100 of the second embodiment is designed as an additive component and has a spiral channel 103. As can be seen in Figure 3, a liquid exiting the damping device 6 enters the spiral channel 103 and must overcome several spiral turns to reach the second sub-chamber 5b. This slows down the kinetic energy of the liquid during the closing process of the gas injector, thus preventing foam formation in the compensation chamber 5.

[0089] Figure 4 shows a third embodiment of the invention, wherein separator 100 is formed integrally with a housing component 51 of the damping device 6. The separator 100 and the housing component 51 are designed as a single additive component. The separator 100 has a settling chamber 104 for the liquid flowing in from the throttle and further bores, as well as several undercuts 105 and several through-openings 106. As indicated by arrows B, this results in a labyrinthine flow through the separator 100, allowing the kinetic energy of the liquid to be dissipated.

[0090] Figure 5 shows a fourth embodiment of the invention, in which the separator 100, the housing 50 of the compensation chamber 5 and the damping housing 60 R.414681

[0091] - 13 - of the damping device 6 are manufactured as a single, additively manufactured component; the throttle 26 is also additively manufactured. Furthermore, a closable filling opening 107 for filling the lubricant chamber with fluid is provided in the housing 50. Thus, the additively manufactured component of the fourth embodiment comprises several individual functional components of the lubricant chamber, which significantly reduces assembly costs. Additive manufacturing also makes it possible to design the porous area 101 of the separator 100 with continuous pores and to make the housing components fluid-tight.

[0092] It should be noted that it is of course also possible that the separator has a porous area and undercuts with through-openings and / or a spiral channel.

[0093] Figures 6 to 8 show further embodiments of the invention.

[0094] Figure 6 shows a fifth embodiment in which the separator 100 has a cylindrical hat-shaped design in cross-section. The liquid flowing out of the throttle 62 is deflected multiple times. These flow deflections reduce the kinetic energy of the outgoing liquid, thus reducing the risk of gas and liquid mixing in the compensation chamber 5.

[0095] Figure 7 shows a sixth embodiment in which a settling chamber 108 is provided immediately after the throttle 62. The fluid flowing out of the throttle 62 must also undergo several deflections before reaching the equalization chamber 5 in order to reduce the kinetic energy of the fluid.

[0096] Figure 8 shows a seventh embodiment of the invention. As can be seen in Figure 8, a cylindrical guide section 109 is provided in the equalization chamber 5 immediately after exiting the throttle 62. This guide section directs the liquid exiting the throttle essentially parallel to the axial direction XX of the gas injector. As a result, at least a portion of the liquid flowing from the throttle 62 directly impacts the separator 100 and is deflected. This creates turbulence in the settling chamber 108, which leads to the dissipation of kinetic energy. (See R.414681)

[0097] - 14 - The liquid must then pass through several channels to reach the actual equalization chamber 5. The equalization chambers and separators shown in Figures 6 to 8 are manufactured using additive manufacturing.

[0098] For all embodiments, it should be noted that the compensation spaces 5 are preferably manufactured by additive manufacturing with a metal material. Alternatively, in all embodiments, it would also be conceivable that

[0099] Parts or complete compensation chambers 5 are additively manufactured from a plastic material. It is also possible to incorporate metallic inserts, such as separators 100. Alternatively, the separators can be manufactured as porous components.

Claims

R.414681 - 15 - 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 anchor bolt (24), wherein the valve needle (31) releases and closes a gas path (14) at a sealing seat (11) arranged at a first end of the gas injector, wherein the anchor (20) is connected to the anchor bolt (24) and the anchor bolt (24) is in operative communication with the valve needle (31), - a closed lubricant chamber (4) which is filled with a liquid (40) as a lubricant, and in which the anchor (20) and the anchor bolt (24) are arranged, wherein the lubricant provides a lubricating effect in the lubricant chamber (4), - a reset element (10) which returns the closing element (3) to the closed starting 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), and - a compensation chamber (5) which is part of the lubricant chamber (4) and in which fluid (40) is arranged, - wherein at least one component of the lubricant chamber (4) is an additive component which is produced by an additive process.

2. Gas injector according to claim 1, wherein a gas (41) is arranged in the lubricant chamber (4) in addition to the liquid (40), wherein the gas is arranged in the compensation chamber (5).

3. Gas injector according to one of the preceding claims, wherein the additive component is a separator (100) which is located in the compensation chamber (5) R.414681 - 16 - is arranged and divides the compensation space into a first subspace (5a) and a second subspace (5b).

4. Gas injector according to claim 3, wherein the separator (100) designed as an additive component has a porous area (101) with through pores (102).

5. Gas injector according to one of the preceding claims, wherein the additive component has an undercut (105).

6. Gas injector according to one of the preceding claims, wherein the additive component has an undercut channel, in particular a spiral channel (103), which connects a side of the separator (100) directed towards the damping device (6) with an opposite side of the separator.

7. Gas injector according to one of claims 3 to 6, wherein the separator (100) is formed in one piece with a housing component (50) of the compensation chamber (5).

8. Gas injector according to one of claims 3 to 7, wherein the separator (100) is formed in one piece with a damping housing (60) of the damping device (6).

9. Gas injector according to one of claims 3 to 8, wherein the separator (100) is formed in one piece with a component of the damping device (6) in which a throttle (26) is arranged.

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