Gas injector

Abstract

The present invention relates to a gas injector for injecting a gaseous fuel, comprising a magnetic actuator with an armature, an inner pole and a coil, a closing element with a valve needle and an armature pin, wherein the valve needle opens and closes a gas path at a sealing seat arranged at a first end of the gas injector, wherein the armature is connected to the armature pin and the armature pin is in operative communication with the valve needle, a sealed lubricant chamber filled with a liquid as a lubricant and a gas, in which the armature and the armature pin are arranged, wherein the lubricant provides a lubricating effect in the lubricant chamber, a reset element which returns the closing element to the closed initial position, a compensation chamber which is part of the lubricant chamber and in which liquid and gas are arranged, a damping device,which is arranged in the lubricant chamber, wherein the damping device is configured to dampen a closing movement of the closing element, wherein the damping device has a throttle which provides a fluid connection from the damping device to the compensation chamber, and wherein the throttle has a cylindrical first section and a tapered second section, the tapered second section being directed towards the compensation chamber.

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] The gas injector according to the invention for injecting a gaseous fuel, comprising 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. Moreover, the damping performance can be improved, particularly with regard to refilling the damper with a damping fluid. This results in the significant advantage that the gas injector can be operated with shorter actuation times, in particular less than or equal to 2 ms, preferably 1.5 ms.In particular, this enables multiple injections, whereby damping of the moving parts of the gas injector is possible during each individual injection, despite the short actuation times. A further major advantage of the damping possible according to the invention during all movements of the moving parts of the gas injector is that the damping, which can be performed at any time, prevents vibration excitation of other components of the gas injector. This results in significantly reduced stress on the components of the gas injector.

[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 each other at opposite end faces and are movable independently of each other. The gas injector further includes a lubricant chamber, enclosed 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. The damping device includes a throttle that provides a fluid connection to the compensation chamber. The throttle has a cylindrical first section and a tapered second section. The tapered second section faces the compensation chamber and widens towards it.This makes it possible to quickly refill the damping device with liquid for damping after damping has been achieved, thus ensuring a damping option even with short control times, both when opening and closing the gas injector.

[0005] The dependent claims describe preferred embodiments of the invention.

[0006] The tapered second section of the throttle is particularly preferred as having a conical shape. This allows the second section to be manufactured easily and with minimal tolerances.

[0007] Preferably, the angle α of the conical second sub-section lies in a range of 30° ≤ α ≤ 60°. Particularly preferably, the angle lies in a range of 40° ≤ α ≤ 50°.

[0008] The throttle preferably has a first edge at a first free end of the first sub-section, directed towards the damping device, a second edge at the transition between the first and second sub-sections, and a third edge at the second free end of the second sub-section, directed towards the compensation chamber. At least one of the three edges has a chamfer. Particularly preferably, the second and third edges, i.e., the edges at the tapered second sub-section, each have a chamfer. The chamfer ensures a defined transition between the respective sections. Surprisingly, it has been shown that chamfered edges on the throttle enable significantly faster refilling of the damping device with liquid.The defined edge fractures facilitate the flow of liquid after damping, during which liquid is forced out of the damping device. This allows for the shortest possible response times for a gas injector that also enables damping of the moving components.

[0009] Preferably, only the two edges on the cylindrical first section are provided with an edge break.

[0010] Preferably, all three edges of the throttle are provided with a defined edge break.

[0011] The defined edge break preferably has a chamfer with a length F in a range between 0.04 mm ≤ F ≤ 0.1 mm, particularly in the range between 0.06 mm ≤ F ≤ 0.08 mm.

[0012] Preferably, the edge chamfer is executed with the same dimension on all edges. This ensures that the edge chamfers are identical on all edges, which can, in particular, prevent the influence of manufacturing tolerances on the damping function.

[0013] 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.

[0014] The damping chamber of the damping device is preferably pot-shaped, and the throttle is arranged at the bottom of the pot-shaped damping chamber. This allows for a particularly compact and simple design.

[0015] 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. Brief description of the drawings

[0016] A preferred embodiment of the invention is 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 the damping device of Fig. 2, and Fig. 4 An enlarged partial sectional view of a throttle of the damping device of Fig. 2. Preferred embodiment of the invention

[0017] The following refers to the Fig. 1 to 4 a gas injector 1 according to a first preferred embodiment of the invention is described in detail.

[0018] Fig. Figure 1 shows the closed state of gas injector 1.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] The closing element 3 opens or closes a passage for the injection of gaseous fuel at the sealing seat 11.

[0023] In Fig. Figure 1 schematically shows an electrical connection 13, which is led through the main body 7 to the magnetic actuator 2.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] Most of the lubricant chamber 4 is filled with the liquid lubricant.

[0028] This ensures, in particular, lubrication of the armature 20 during operation. The return element 10 is also located in the lubricant chamber.

[0029] 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.

[0030] The damping device 6 is in detail made of Fig. 2 is evident.

[0031] 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.

[0032] The damping piston 61 is cylindrical and has a through-opening 64 which runs in a central axis of the gas injector.

[0033] The damping device 6 further comprises a return element 65 for returning the damping piston 61 to its position. Fig. 2 Starting positions shown.

[0034] 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 61 and the damping housing 60.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] The throttle 62 of the damping device 6 is detailed from the Fig. 3 and Fig. 4. The throttle 62 provides a fluid connection from the damping device 6 to the compensation chamber 5, wherein the throttle 62 has a cylindrical first section 62a and a tapered second section 62b. The tapered second section 62b is conical and directed towards the compensation chamber 5 (compare Fig. 3).

[0040] An angle a of the conical second sub-section 62b is preferably in a range of 30° ≤ a ≤ 60° and is approximately 50° in this embodiment.

[0041] The throttle 62 has a total length L in the axial direction XX. The first length L1 of the cylindrical first section 62a is greater than the second length L2 of the conical second section 62b. The first length L1 is therefore greater than half the total length L of the throttle 62.

[0042] The throttle 62 further comprises three edges. A first edge 621 is located at a first free end of the first sub-section 62a. A second edge 622 is formed at the transition between the first sub-section 62a and the second sub-section 62b. A third edge 623 is formed at the second free end of the throttle 62 at the second sub-section 62b (compare Fig. 3).

[0043] In this embodiment, all three edges 621, 622, and 623 have a chamfer. That is, the three edges 621, 622, and 623 are not sharp edges, but have a chamfer 69 (compare Fig. 4).

[0044] The chamfer 69 has a length F of approximately 0.07 mm at the third edge 623. Preferably, the second edge 622 and the first edge 621 have the same chamfer length F or, alternatively, different chamfer lengths F.

[0045] The edge chamfering of the three edges 621, 622, 623 surprisingly improves performance both when refilling the damping device 6 and during the actual damping process.

[0046] As explained above, when the damping piston 61 opens, it moves in the direction of arrow A, so that fluid from the compensation chamber 5 flows into Fig. 3, schematically indicated by arrows B, must flow into the damping chamber 63. During the closing process, fluid must flow from the damping chamber 63 back into the compensation chamber 5 under damping effect through the throttle 62, whereby the damping function is performed during the return process, which is shown in Fig. 2 is indicated by the arrows C.

[0047] The combination of the tapered second section 62b together with the chamfered edges 621, 622, 623 enables a surprisingly significant improvement in the performance of the damping device 6 with regard to the flow of liquid through the throttle 62. This makes it surprisingly possible to implement a gas injector with significantly shorter actuation times, which allows a damping function for the moving components to be provided during all switching operations of the gas injector.

[0048] In addition, the now defined edges in the form of the defined chamfers 69 significantly reduce the tolerance sensitivity of the damping function of the gas injector. This means that the damping function of the gas injector remains consistently good throughout its service life. The defined chamfers, preferably on all three edges, prevent manufacturing tolerances during the production of the throttle from influencing the damping function, which could lead to different damping behaviors between different gas injectors.

[0049] The invention can thus provide an operating behavior of the gas injector with significantly reduced control times through a relatively simple measure of optimizing the throttle.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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.

[0054] 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 C. 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.

[0055] The anti-mixing device 100 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 101 and is significantly slowed down. Since the connecting openings 102 have very small diameters, this prevents rapidly flowing liquid from entering the second sub-chamber 5b of the compensation chamber 5. This prevents foam formation 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 62 or the damping chamber 63. The optimized geometry of the throttle 62, especially through edge chamfering and the provision of a conical section, also reduces the risk of foam formation in the compensation chamber 5.

[0056] 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.

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 a gas (41), 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 compensation chamber (5) which is part of the lubricant chamber (4) and in which liquid (40) and gas (41) are arranged, - 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), - wherein the damping device (6) has a throttle (62) which provides a fluid connection from the damping device (6) to the compensation chamber (5), and - wherein the throttle (62) has a cylindrical first section (62a) and a tapered second section (62b), wherein the tapered second section (62b) is directed towards the compensation chamber (5). [2] Gas injector according to claim 1, wherein the tapered second part (62b) is conical. [3] Gas injector according to claim 2, wherein the conical second part section (62b) has a cone angle in a range of 30° to 60°. [4] Gas injector according to one of the preceding claims, wherein the throttle (62) has a first edge (621) at a first free end of the first sub-region (62a), a second edge (622) at the transition between the first and second sub-region of the throttle (62) and a third edge (623) at the second free end of the second sub-region (62b) and wherein at least one of the edges (621, 622, 623) has an edge break. [5] Gas injector according to claim 4, wherein the throttle (62) has an edge break at the first edge (621) and the second edge (622). [6] Gas injector according to claim 4, wherein the throttle (62) has an edge break on the second edge and on the third edge. [7] Gas injector according to claim 4, wherein the throttle (62) has an edge break at the first edge, the second edge and the third edge. [8] Gas injector according to any one of claims 4 to 7, wherein the edge (621, 622, 623) has an edge break with a chamfer (69) over a length (F) in a range of 0.04 mm to 0.1 mm. [9] Gas injector according to one of the preceding claims, wherein the throttle (62) on the first sub-section (62a) has a first axial length (XX) which is greater than a second length (L2) of the second sub-section (62b). [10] Gas injector according to one of the preceding claims, further comprising an anti-mixing device (100) which is arranged in the compensation chamber (5) and is configured to prevent mixing of liquid (40) and gas (41) in order to prevent foam formation in the compensation chamber (5).

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