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 with a gas 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 a 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; a compensation chamber which forms part of the lubricant chamber and in which liquid and gas are present; and a movable separating element which is arranged in the compensation chamber and which fluid-tightly separates the liquid from the gas.

Description

[0001] R.414721

[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.414721 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, 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 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 gas path passing by. 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 and the gas are arranged. The partially filled with gas R.414721.

[0013] - 3 - The filled lubricant chamber thus allows for simple volume expansion, particularly if temperature-related volume changes of components and / or the fluid occur 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.

[0014] The gas injector also includes a movable separating element, which is arranged in the compensation chamber and tightly separates the liquid from the gas. This reliably prevents the liquid and gas from mixing in the compensation chamber. Because the separating element is both sealing and movable, temperature-related expansion processes of the liquid and / or the gas and / or components can be compensated for by the corresponding movement of the separating element.

[0015] 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.

[0016] The dependent claims describe preferred embodiments of the invention.

[0017] The separating element preferably divides the compensation chamber into a gas-filled first subchamber, which is filled exclusively with gas, and a liquid-filled second subchamber, which is filled exclusively with liquid. The gas-filled first subchamber is preferably arranged at an end of the lubricant chamber facing away from the sealing seat.

[0018] Preferably, the movable separating element is a movable membrane. The membrane is fluid-tight and can change its position in the compensation chamber during temperature-induced expansion processes, thus enabling compensation. The membrane is preferably a rolling membrane and, in particular, has a movable fold for volume adjustment in the compensation chamber. The membrane can also be made of a stretchable material and perform compensation through expansion processes. R.414721

[0019] - 4 -

[0020] Preferably, the movable diaphragm is formed with a bead on the outer circumference of the diaphragm to enable the diaphragm to be fixed to components of the gas injector, in particular components which define the enclosed lubricant chamber.

[0021] The movable membrane is preferably circular in shape.

[0022] The separating element preferably comprises a piston which is arranged in abutting the diaphragm. The piston serves in particular to stabilize the diaphragm. The piston is preferably arranged in the gas-filled first sub-chamber of the compensation chamber.

[0023] Particularly preferably, the piston is designed in a pot shape and the movable diaphragm is located on the outer circumference of the piston and on an end face of the piston.

[0024] The membrane is preferably made of a flexible material. It is further preferably fabric-reinforced, particularly in the areas that are in contact with the piston.

[0025] Particularly preferred is the movable fold of the diaphragm arranged between the outer circumference of the piston and an inner wall of the compensation chamber. This allows for stabilization of the diaphragm fold and guidance of the diaphragm during movement.

[0026] Alternatively, the movable separating element is a movable piston with a piston seal on its outer circumference that seals against an inner wall of the equalization chamber. The movable piston can be provided particularly easily and cost-effectively. The piston seal ensures the reliable separation of gas and liquid. During operation, the movable piston thus assumes a position in which a pressure equilibrium exists between the gas-filled first sub-chamber and the liquid-filled second sub-chamber.

[0027] The piston seal preferably comprises one or more elastic sealing rings arranged around the circumference of the piston. R.414721

[0028] - 5 -

[0029] A particularly preferred configuration of the piston seal is such that piston movement is achieved solely through elastic deformation of the piston seal itself. In this configuration, the piston seal is not displaced axially; rather, the position of the piston changes due to this elastic deformation. The piston seal can, for example, be designed as an O-ring with a very large cross-section to facilitate this elastic deformation and the resulting change in the piston's position.

[0030] The gas injector preferably comprises a preload element that axially biases the movable piston or the stabilizing piston of the diaphragm. The preload element is preferably arranged in the gas-filled first sub-chamber. The preload element is, for example, a helical spring.

[0031] Alternatively, a preload can be applied to the movable piston or the piston on the diaphragm by selecting a pressure in the gas-filled first subchamber. A combination of increased pressure in the gas-filled first subchamber and a preloading element is also conceivable.

[0032] 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.%.

[0033] 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 a central axis of the R.414721.

[0034] - 6 -

[0035] Gas injector. Due to the throttle, very high flow velocities of the liquid can occur locally in the lubricant chamber during operation, which are slowed down by the separating element according to the invention.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] Brief description of the drawings

[0040] Preferred embodiments of the invention are described in detail below with reference to the accompanying drawing. The drawing shows:

[0041] Figure 1 shows a schematic sectional view of a gas injector according to a first preferred embodiment of the invention.

[0042] Figure 2 shows an enlarged partial sectional view of a damping device and a compensation chamber of the gas injector of Figure 1.

[0043] Figures 3 to 5 Partial sectional views of the equalization chamber at different temperatures, R.414721

[0044] - 7 -

[0045] Figure 6 shows a partial sectional view of a gas injector according to a second embodiment of the invention, and

[0046] Figures 7 to 9 show partial sectional views of the compensation chamber of the gas injector from Figure 6 at different temperatures.

[0047] Preferred embodiments of the invention

[0048] A gas injector 1 according to a first preferred embodiment of the invention is described in detail below with reference to Figures 1 to 5.

[0049] Figure 1 shows the closed state of gas injector 1.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] The closing element 3 either opens or closes a passage for the injection of the gaseous fuel.

[0054] Figure 1 schematically shows an electrical connection 13, which is routed through the main body 7 to the magnetic actuator 2. R.414721

[0055] - 8 -

[0056] 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.

[0057] 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 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 housing 50 of 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.

[0058] The gas injector 1 is shown in a vertical installation position. The axial direction XX is vertically oriented. The gas 41 is separated from the liquid 40 in the compensation chamber 5 by a movable separating element 9.

[0059] The movable separating element 9 is thus arranged in the compensation chamber 5 and provides a fluid-tight separation of gas and liquid. This prevents the gas and liquid from mixing.

[0060] The movable separating element 9 is, as can be seen in particular from Figure 2, a movable, flexible membrane 92 which has a fold 92a, a bead 92b and a thickened area 92c.

[0061] The fold 92a of the membrane 92 allows the membrane to move in the axial direction XX without being subjected to stretching. The fold 92a thus makes the membrane a rolling membrane.

[0062] The separating element 9 divides the equalization chamber 5 into a gas-filled first subchamber 5a and a liquid-filled second subchamber 5b. The first subchamber 5a is completely filled with gas and the second subchamber 5b is completely filled with liquid. R.414721

[0063] - 9 -

[0064] The separating element 9 further comprises a preloading element 93, which preloads the separating element 9 in the axial direction XX. The preloading element 93 is arranged in the gas-filled first subspace 5a and is designed as a helical spring.

[0065] As can be seen further in Figure 2, the diaphragm 92 rests with a first side of the fold 92a against an outer circumference 91a of the piston 91 and with the thickened area 92c against the end face of the piston 91. This ensures excellent stability of the movable diaphragm 92.

[0066] In particular, since a second side of the fold 92a rests against an inner wall 5c of the compensation space 5, rolling movements of the fold 92a can be safely enabled during temperature-related expansion processes.

[0067] Most of the lubricant chamber 4 is filled with the liquid lubricant.

[0068] This ensures, in particular, lubrication of the armature 20 during operation. The return element 10 is also located in the lubricant chamber.

[0069] Furthermore, the gas injector 1 includes 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.

[0070] The damping device 6 is shown in detail in Figure 2.

[0071] 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.

[0072] The damping piston 61 is cylindrical and has a through-hole 64 which runs along a central axis of the gas injector. R.414721

[0073] - 10 -

[0074] The damping device 6 further comprises a return element 65 for returning the damping piston 61 to the initial position shown in Figure 2.

[0075] 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.

[0076] 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.

[0077] 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.

[0078] 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. During this process, 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.

[0079] 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, this fluid from R.414721 must be used to reset the damping piston 61.

[0080] - 11 - displace the damping chamber 63. Since the guide gap 6a in the guide area 66 is very narrow, this displacement occurs essentially exclusively via the throttle 62 into the compensation chamber 5.

[0081] Thus, liquid from the throttle 62 enters the second sub-chamber 5b of the compensation chamber 5 at high speed, as shown by arrows B in Figure 2. Without the separating element 9, a very strong flow would therefore be generated at the liquid surface in the compensation chamber 5 due to the high-speed inflow of liquid, which could lead to foaming.

[0082] Furthermore, the movable separating element 9 can perform axial movements XX during operation, in particular to maintain a constant pressure in the liquid-filled second sub-chamber 5b. Figures 3 to 5 schematically illustrate the axial position of the separating element 9 at different temperatures. Figure 3 shows the position of the separating element 9 at a temperature of approximately -40°C. Figure 4 shows the axial position of the separating element 9 at a temperature of approximately +20°C. Figure 5 shows the axial position of the separating element 9 at a temperature of approximately +120°C. A comparison of the diaphragm 92 in Figures 3 to 5 shows the change in the fold 92a when the diaphragm 92 rolls, in particular, against the inner wall 5c of the compensation chamber 5 and the outer circumference 91a of the piston 91.When the temperature drops again from the state shown in Figure 5, the separating element 9 is reset by the prestressed prestressing element 93 and the pressure built up in the gas-filled first sub-chamber 5a.

[0083] The movement of the separating element 9 in the axial direction XX is schematically indicated by the arrow C in Fig. 4.

[0084] The diaphragm 92 is circular and fixed to the bead 92b between the housing 50 of the compensation chamber 5 and the damping housing 60. The thickened area 92c of the diaphragm 92 rests against the end face 91b of the piston 91.

[0085] The length of the fold 92a of the membrane is chosen such that, at all extreme positions of the movable separating element 9, the thickened area 92c R.414721

[0086] - 12 - always rests against the front face 91 b of the piston 91. A part of the fold 92a of the diaphragm 92 also always rests against the outer circumference 91 a of the piston 91 and against the inner wall 5c of the housing 50 of the compensation chamber 5 (see Figures 3 to 5).

[0087] Thus, the movable separating element 9 enables a strict separation between the liquid and the gas in the lubricant chamber 4. The rolling movement of the fold 92a of the membrane 92 during a movement of the separating element 9 ensures that the membrane 92 is not damaged.

[0088] If necessary, the membrane 92 can be reinforced with fibers, especially at the contact areas with the housing 50 and the piston 91.

[0089] Figures 6 to 9 show a gas injector according to a second embodiment of the invention, wherein identical or functionally identical parts are designated with the same reference numerals as in the first embodiment.

[0090] As can be seen from Figure 6, the movable separating element 9 of the second embodiment is a piston 109. The piston 109 is arranged in the compensation chamber 5 and separates the gas in the first subchamber 5a from the liquid in the second subchamber 5b in a fluid-tight manner.

[0091] The piston 109 has a piston seal 110 on its outer circumference. As can be seen from Figure 6, the piston seal 110 comprises three sealing elements, namely a first sealing element 111, a second sealing element

[0092] 112 and a third sealing element 113. The three sealing elements 111, 112, 113 are arranged on the outer circumference of the piston 109 and seal against an inner wall 5c of the housing 50 of the compensation chamber 5.

[0093] Figures 7 to 9 again show, as in the first embodiment, different positions of the separating element 9 of the second embodiment as a function of temperature. The piston seal 110 is designed to allow large axial strokes, as shown with the temperature changes in Figures 7 to 9, without leakage and without a stick-slip effect of the piston 109. The first sealing element 111 has a larger cross-section than the second and third sealing elements 112.

[0094] 113. The first sealing element 111 is arranged such that small axial R.414721

[0095] - 13 -

[0096] Strokes that may occur, for example, due to movement of the closing element during opening and / or closing processes, are to be achieved via an elastic self-deformation of the first sealing element 111. In this process, the first sealing element 111 is not axially displaced, but only the piston 109. These small axial strokes are preferably less than 2 mm, and in particular less than 1 mm.

Claims

R.414721 - 14 - 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 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 - a movable separating element (9) which is arranged in the compensation chamber (5) and separates the liquid (40) from the gas (41) in a fluid-tight manner.

2. Gas injector according to claim 1, wherein the movable separating element (9) divides the compensation space (5) into a gas-filled first subspace (5a) which is filled exclusively with gas and a liquid-filled second subspace (5b) which is filled exclusively with liquid.

3. Gas injector according to one of the preceding claims, wherein the movable separating element (9) is a movable membrane (92), in particular a R.414721 - 15 - Rolling membrane, which in particular has a movable fold (92a) for volume adjustment in the compensation space (5).

4. Gas injector according to claim 3, wherein the movable membrane (92) has a bead (92b) on its outer circumference for fixing the membrane (92).

5. Gas injector according to claim 3 or 4, wherein the separating element (9) further comprises a piston (91) which rests against the diaphragm (92).

6. Gas injector according to claim 5, wherein the piston (91) is pot-shaped and the movable diaphragm (92) is located on the outer circumference (91 a) of the piston (91) and on an end face (91 b) of the piston (91) for stabilization.

7. Gas injector according to one of claims 5 or 6, wherein the movable fold (92a) rests against an inner wall (5c) of the compensation chamber (5) and against the outer circumference (91a) of the piston (91) for stabilization.

8. Gas injector according to claim 1 or 2, wherein the movable separating element (9) is a movable piston (109) which has a piston seal (110) on its outer circumference, sealing against an inner wall (5c) of the compensation chamber (5).

9. Gas injector according to claim 8, wherein the piston seal (110) has several sealing elements (111 , 112, 113).

10. Gas injector according to claim 8 or 9, wherein the piston seal (110) has a sealing element (111) which is designed as an elastic sealing ring.

11. Gas injector according to claim 10, wherein the elastic sealing ring is arranged to perform a movement of the piston (109) only by elastic self-deformation, wherein the elastic sealing ring itself is not axially displaced.

12. Gas injector according to one of claims 5 to 11, further comprising a preloading element (93) which is configured to preload the movable separating element (9). R.414721 - 16 - 13. Gas injector according to claim 12, wherein the preloading element (93) is arranged in the gas-filled first subspace (5a).

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