Gas injector with a damper

Abstract

The invention relates to a gas injector for injecting a gaseous fuel, comprising: a solenoid actuator (2) with an armature (20), an inner pole (21), and a coil (22); a closing element (3) which releases and closes a gas path (14) on a seal seat (11), said armature (20) being operatively connected to the closing element (3); a closed lubricant chamber (4) which is filled with a lubricant and which is arranged in the armature (20) in order to ensure a lubrication of the armature; and a damping device (6) which is arranged in the lubricant chamber (4), said damping device (6) being designed to damp a closing movement of the closing element (3). The damping device (6) has a damping piston (61), a damping housing (60), a throttle (62), and a damping chamber (63) formed in the damping housing (60), wherein the throttle (62) connects the damping chamber (63) to a compensation chamber (54), the throttle is arranged in the damping housing (60), and a guide region (66) with a guide clearance is formed between the damping piston (61) and the damping housing (60).

Description

[0001] Description

[0002] title

[0003] State of the art

[0004] The present invention relates to a gas injector for injecting a gaseous fuel, in particular hydrogen or natural gas or the like, with improved damping properties. The gas injector is designed in particular for direct injection into a combustion chamber of an internal combustion engine.

[0005] Gas injectors are known in various designs from the state of the art. One of the problems with gas injectors is their relatively difficult damping, especially during the closing process of the gas injector.

[0006] Disclosure of the invention

[0007] The gas injector according to the invention for injecting a gaseous fuel with the features of claim 1 has the advantage that precise damping properties can be achieved, particularly during a closing process of the gas injector. In particular, the damping properties can be precisely adjusted. This makes it possible to realize different damping characteristics for gas injectors from different manufacturers of internal combustion engines. Furthermore, the gas injector according to the invention enables a stable damping function over the entire service life of the gas injector. Damping by the gas injector according to the invention is also possible without the negative influence of any gas bubbles that may be present in the area of ​​the damper. In this way, damage to the components of the gas injector, in particular to a damper device, due to cavitation, can also be prevented.

[0008] This is achieved according to the invention in that the gas injector comprises a magnetic actuator with an armature, an inner pole and a coil. A closing element, which can be actuated by the magnetic actuator, is arranged such that a gas path through the gas injector is opened and closed at a sealing seat. The closing element is operatively connected to the armature of the magnetic actuator. Furthermore, a sealed lubricant chamber is provided which is filled with a lubricant and in which the armature of the magnetic actuator is arranged. The lubricant chamber thus ensures lubrication of the armature during operation, thereby increasing its service life. The lubricant is preferably an oil or another liquid. The gas injector further comprises a damping device which is arranged in the lubricant chamber. The damping device is designed to dampen the closing movement of the closing element.The damping device comprises a damping piston, a damping housing, a throttle, and a damping chamber formed in the damping housing. The throttle connects the damping chamber to the lubricant chamber, in particular to a compensation chamber for the lubricant. A guide area is formed between the damping piston and the damping housing. This guides the damping piston in the damping housing. The guide preferably extends over the entire axial length of the damping piston. The guide clearance between the damping piston and the damping housing is very tight.

[0009] The damping device is thus designed to enable braking of the closing element during a closing movement of the closing element from the open state towards the closed state of the closing element, in particular shortly before the closing element impacts a sealing seat. In this way, wear on a sealing seat of the gas injector, which could be caused by excessive impact of the closing element on the sealing seat, can be reduced or completely prevented. The gas injector nevertheless has a relatively simple and cost-effective design and is therefore suitable for mass production. The throttle in the damping housing thus enables the guide area between the damping piston and the damping housing to be as narrow as possible, so that no throttling occurs in the area of ​​the guide area.The guide area can thus be designed exclusively for the axial guidance of the damping piston. The tight guide clearance between the damping piston and the damping housing ensures that the lubricant to be displaced is guided through the throttle and does not escape through a guide gap between the damping piston and the damping housing. This enables the damping device to achieve very precise damping properties.

[0010] The subclaims show preferred developments of the invention.

[0011] The throttle of the damping device is preferably designed such that a throttle length of the throttle in the axial direction of the gas injector is less than or equal to a throttle diameter. The throttle preferably has a constant diameter. Thus, the throttle is designed as an orifice plate, whereby the throttle properties can be easily selected by selecting the throttle length and / or the throttle diameter. This also allows for particularly simple adaptation of the damping device to different requirements of the gas injector, for example, requirements of different internal combustion engine manufacturers.

[0012] Particularly preferably, the damping chamber is pot-shaped, and the throttle of the damping device is arranged at the bottom of the pot-shaped damping chamber. This allows for a particularly compact and simple design.

[0013] The bottom of the damping chamber, in which the throttle is arranged, is preferably a conical bottom with a tip. The throttle is arranged at the tip of the conical bottom.

[0014] The damping chamber, in which the damping piston moves back and forth, is preferably designed without undercuts. This eliminates areas where, for example, cavitation bubbles could form, which could cause damage to the components if they collapse. The damping piston is preferably cylindrical.

[0015] Further preferably, a conical outflow is provided, extending from the damping chamber and facing away from the combustion chamber, downstream of the throttle, for the lubricant flowing through the throttle during the closing process. A diffuser is thus located downstream of the throttle. The diffuser thus enables a pressure increase in a compensation chamber downstream of the throttle, which can prevent cavitation bubbles during operation.

[0016] Alternatively, a throttle outlet into the downstream compensation chamber is preferably formed by means of sharp edges.

[0017] Preferably, the damping housing has an outwardly projecting area at the bottom, in which the throttle is formed. This allows the damping chamber to be easily formed with a conical bottom. If the damping piston is cylindrical, a certain volume of lubricant always remains in the damping chamber, particularly in its conical end region.

[0018] The damping piston is further preferably preloaded by means of a spring element. The spring element preferably engages a radially outwardly directed flange of the damping piston and is arranged between the flange and the damping housing.

[0019] To enable a rapid opening of the gas injector, the damping piston preferably has a through-opening in the axial direction. The through-opening connects the bottom area of ​​the damping chamber with the end of the damping piston facing the closing element.

[0020] The gas injector is preferably an outward-opening gas injector. The closing element is preferably a one-piece or multi-piece valve needle, preferably with a seat plate for contact with the sealing seat in the closed state.

[0021] Brief Description of the Drawings Preferred embodiments of the invention are described in detail below with reference to the accompanying drawings. In the drawing:

[0022] Figure 1 A schematic sectional view of a gas injector according to a first preferred embodiment of the invention,

[0023] Figure 2 is an enlarged partial sectional view of the damping device of Figure 1, and

[0024] Figures 3 to 6 show various alternatives of throttles of damping devices according to further embodiments of the invention.

[0025] Preferred embodiments of the invention

[0026] A gas injector 1 according to a first preferred embodiment of the invention will be described in detail below with reference to Figures 1 and 2.

[0027] Figure 1 shows the closed state of the gas injector 1.

[0028] 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 brings a closing element 3, which in this embodiment is an outwardly opening valve needle, from a closed state to an open state.

[0029] The magnetic actuator 2 comprises an armature 20, which rests against the locking element 3 by means of an armature bolt 24. Furthermore, the magnetic actuator 2 comprises an inner pole 21, a coil 22, and a magnet housing 23, which ensures a magnetic return path of the magnetic actuator.

[0030] The gas injector 1 further comprises a main body 7 with a connection area 70, through which the gaseous fuel is supplied to an interior area 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.

[0031] The closing element 3 opens or closes a passage for the injection of the gaseous fuel.

[0032] Figure 1 schematically shows an electrical connection 13 which is guided through the main body 7 to the magnetic actuator 2.

[0033] 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.

[0034] The gas injector 1 further comprises a sealed lubricant chamber 4, which is completely or partially filled with a liquid lubricant, preferably oil. 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 flexible component 53, which defines a compensation chamber 54. The flexible component 53 is preferably another bellows with a closed end.

[0035] The lubricant chamber 4 is preferably completely filled with a lubricant. This ensures, in particular, lubrication of the armature 20 during operation. The return element 10 is also arranged in the lubricant chamber.

[0036] 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 after the armature 20, starting from the sealing seat.

[0037] The damping device 6 can be seen in detail in Figure 2. 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 the initial position shown in Figure 2.

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

[0041] 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 firmly connected to the armature bolt 24, toward the inner pole 21. Since the armature bolt 24 is in direct contact with the closing element 3, the closing element 3 is lifted from the sealing seat 11, allowing gas to be injected into the combustion chamber 30.

[0042] In the damping device 6, the spring force of the return element 65 moves the damping piston 61 in the direction of the guide component 25, which is indicated in Figure 2 by the arrow A. As a result, the gap 26 is overcome and the volume of the damping chamber 63 increases. Lubricant can flow into the damping chamber 63 via the throttle 62 and also via the through-opening 64. When the gas injector closes, the current supply to the magnetic actuator 2 is stopped, so that the return element 10 returns the closing element 3 and the armature bolt 24 back towards their closed position. The armature bolt 24 comes into contact with the end face 61b of the damping piston 61 and moves it opposite to the opening direction A.

[0043] Since only a very narrow guide gap 6a exists between the damping piston 61 and the damping housing 60 at a guide area 66, fluid must be displaced from the damping chamber 63 in order to retract the damping piston 60. 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 54.

[0044] Since the dimensions of the throttle can be manufactured very precisely, precise damping of the closing element 3 is possible via the anchor bolt and the damping piston 60. In particular, throttling is independent of the axial length of the guide area 66 between the damping piston 61 and the damping housing 60.

[0045] The throttle 62 is designed such that its axial length is equal to its diameter. Thus, in this exemplary embodiment, the throttle 62 corresponds to an orifice plate. Sharp inlet and outlet edges are provided on both sides of the throttle. Due to the inventive design of the damping device 6, the throttle function is thus independent of the viscosity of the lubricant and thus also independent of the temperature. During operation, the lubricant can heat up, which previously led to problems due to differentially expanding components in the lubricant chamber.

[0046] Furthermore, any gas bubbles that may have formed in the damping chamber 63 can be discharged into the compensation chamber 54 via the throttle 62. Cavitation damage can also be prevented by the inventive design of the damping device 6. Since the damper volume in the damping chamber 6 is thus always free of gas bubbles, stable damping functions of the damping device can be ensured. Thus, by displacing the lubricant from the damping chamber 63, the damping piston 61 and thus also the closing element 3 can be decelerated, preventing the closing element 3 from striking the sealing seat 11 hard. This significantly reduces wear on the gas injector at the sealing seat, significantly improving the service life of the gas injector.

[0047] Figures 3 to 6 show alternative designs of the throttle of the damping device 6.

[0048] Figure 3 shows a configuration according to one exemplary embodiment, wherein the bottom of the damping chamber 63 is conical. This results in a conical inflow to the throttle 62 at a tip of the damping chamber 63.

[0049] Figure 4 shows a third embodiment of the invention, wherein a diffuser 67 is arranged downstream of the throttle 62. This results in a pressure increase immediately downstream of the throttle 62 when the damping piston 61 is returned to its initial position during the closing process.

[0050] Figure 5 shows a fourth embodiment of the invention, wherein the outflow from the throttle 62 toward the compensation chamber 54 occurs via a sharp edge 68. No pre-bore or diffuser or the like is provided.

[0051] Figure 6 shows a fifth embodiment of the invention, in which the damping housing 60 has a protruding portion 69. The throttle 62 is arranged in the protruding portion 69. The damping chamber 63 is enlarged by a conical portion at the bottom of the damping chamber, similar to the second embodiment.

[0052] For all of the illustrated embodiments, it should be noted that any combination of the individual features is possible.

Claims

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) which opens and closes a gas path (14) at a sealing seat (11), wherein the armature (20) is operatively connected to the closing element (3), a closed lubricant chamber (4) which is filled with a lubricant and in which the armature (20) is arranged to ensure lubrication of the armature, and a damping device (6) which is arranged in the lubricant chamber (4), wherein the damping device (6) is designed to dampen a closing movement of the closing element (3), wherein the damping device (6) has a damping piston (61), a damping housing (60), a throttle (62) and a damping chamber (63) formed in the damping housing (60), wherein the throttle (62) connects the damping chamber (63) with a compensation chamber (54),wherein the throttle is arranged in the damping housing (60), and wherein a guide area (66) with guide play is formed between the damping piston (61) and the damping housing (60).

2. Gas injector according to claim 1, wherein an axial length of the throttle (62) is less than or equal to a diameter of the throttle.

3. Gas injector according to one of the preceding claims, wherein the damping chamber (63) is pot-shaped and the throttle is arranged at the bottom of the damping chamber (63).

4. Gas injector according to claim 3, wherein the bottom of the damping chamber (63) is conical with a tip, wherein the throttle (62) is arranged in the tip.

5. Gas injector according to one of the preceding claims, wherein the damping chamber (63) is designed without undercuts.

6. Gas injector according to one of the preceding claims, wherein a conical outflow region is formed between the throttle (62) and the compensation chamber (64).

7. Gas injector according to one of claims 1 to 5, wherein the throttle has a sharp edge (68) at an end directed towards the compensation chamber (54).

8. Gas injector according to one of the preceding claims, wherein the damping chamber (63) has at the bottom a region projecting in the direction of the compensation chamber (54), in which the throttle (62) is formed.

9. Gas injector according to one of the preceding claims, wherein the damping piston (61) is prestressed by means of a spring element (65) in the direction of the sealing seat (11) and, in the closed state, rests against an anchor bolt (24) connected to the closing element (3).

10. Gas injector according to one of the preceding claims, wherein the damping piston (61) has a through opening (64) to enable rapid opening of the gas injector.

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