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) with a valve needle (30) and an armature pin (23), wherein the valve needle (30) releases and closes a gas path (14) on a seal seat (11) arranged on a first end of the gas injector, the armature (20) is connected to the armature pin (23), and the armature pin (23) is operatively connected to the valve needle (30); a closed lubricant chamber (4) which is filled with a lubricant and in which the armature (20) and the armature pin (23) are arranged, said lubricant providing a lubricating effect in the lubricant chamber (4); and a restoring element (10) which restores the closing element (3) to a closed starting position. The lubricant chamber (4) is filled with a gas and a liquid lubricant for damping purposes during movements of the closing element (3), and the ratio of liquid to gas ranges from 70 vol.% / 30 vol.% to 95 vol.% / 5 vol.-%.

Description

[0001] Description

[0002] title

[0003] State of the art

[0004] 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 hydraulic damper.

[0005] Gas injectors are known in various designs from the prior art. Due to the relatively high gas pressures, a closing element, especially a valve needle, makes a hard impact against a sealing seat, 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 costs and maintenance, simple solutions are preferable.

[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 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 particularly robust and cost-effective, making it suitable for mass production of gas injectors. Furthermore, the damping according to the invention requires only a very small installation space. The damping also prevents vibration excitation of other components of the gas injector during the closing process, thus significantly reducing the loads on the other components during operation.

[0008] This is achieved according to the invention in that the gas injector has a magnetic actuator with an armature, an inner pole and a coil. Furthermore, the gas injector comprises 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. As a result, gas is blown into a combustion chamber, for example, or the blowing in is stopped. The closing element further comprises an armature bolt which is connected to the armature and is operatively connected to the valve needle. The valve needle and the armature bolt are preferably rod-like components which rest loosely against one another on opposite end faces and are movable independently of one another. The gas injector further comprises a lubricant chamber which is closed off by means of a lubricant housing and is filled with a lubricant.The armature and the armature bolt are arranged in the lubricant chamber, wherein the lubricant provides a lubricating effect 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 partially provided as a closed 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 gas on a passing gas path. Furthermore, the gas injector comprises a damping device for dampening a closing process of the closing element, which damping device is arranged in the lubricant chamber. The damping device comprises a gas which is arranged in the lubricant chamber, in particular for volume compensation.Thus, a fluid is provided in the lubricant chamber for damping, especially during a closing process.

[0009] The lubricant chamber is enclosed by the lubricant housing, which preferably comprises a plurality of components. The ratio of the liquid, i.e., the liquid lubricant to the gas in the lubricant chamber, is in a range of 70 / 30 vol.% to 95 / 5 vol.%. Particularly preferably, the ratio of liquid to gas is in a range of 80 / 20 vol.% to 90 / 10 vol.%. Further preferably, the ratio of liquid to gas in the lubricant chamber is approximately 85 to 15 vol.%. This ensures that volume equalization is also possible due to the gas in the lubricant chamber.

[0010] A further advantage of the partially gas-filled lubricant chamber is that, in the event of temperature changes that could cause the volume of the liquid lubricant to expand, this expansion can be compensated for by the gas in the lubricant chamber. When the liquid lubricant expands due to temperature changes, the gas in the lubricant chamber is slightly compressed, compensating for the temperature-related volume change of the liquid lubricant.

[0011] By using liquid and gas in the lubricant chamber, it is possible to dispense with complex damping, for example by means of an additional metallic bellows on the lubricant housing intended exclusively for damping.

[0012] Since the lubricant chamber is filled with a gas in addition to the liquid lubricant, a damping device is integrated into the lubricant chamber. This damping device ensures damping of the moving parts located in the lubricant chamber, particularly during a closing process. Furthermore, the damping device enables compensation for temperature-related changes in the length of components in the lubricant chamber or of the housing components of the lubricant housing.

[0013] In particular, thermally induced changes in the length of the closing element can be compensated for. It is also possible, for example, to compensate for thermal volume changes of the liquid lubricant by additional compression of the gas in the lubricant chamber.

[0014] The inventive combined compensation and damping device in the lubricant chamber is a very cost-effective, compact and very robust solution, which is effective over the entire service life of the gas injector.

[0015] The subclaims disclose preferred developments of the invention. The lubricant housing preferably comprises several housing components that define the lubricant chamber. In this case, exactly one housing component of the lubricant housing is a metal bellows. The metal bellows is connected to the closing element. The metal bellows ensures the axial mobility of the closing element during the opening and closing processes. The metal bellows results in a very robust gas injector.

[0016] Particularly preferably, all housing components of the lubricant housing are made of metal. Steel is preferably used as the metal.

[0017] For a particularly robust design, welded joints are provided to connect the metal housing components of the lubricant housing. These welded joints provide a particularly good connection between the housing components of the lubricant chamber and enable a secure seal against the injected gas. Only when hydrogen is used as the gas is it possible for the hydrogen to diffuse through the metal housing components.

[0018] According to a further preferred embodiment of the invention, at least one housing component of the lubricant housing is made of an elastomer material. The elastomer material thus forms part of the shell of the lubricant chamber. The elastomer material in the lubricant housing enables easier diffusion of gases into and out of the lubricant chamber, particularly hydrogen. In particular, hydrogen can diffuse much more easily from the lubricant chamber into the gas path of the gas injector.

[0019] Particularly preferably, the elastomer housing component of the lubricant housing is a sealing plug or a flat gasket. The sealing plug can, for example, be easily provided in an opening in a metallic housing component of the lubricant housing. The elastomer flat gasket is preferably annular and arranged between two flat regions of metallic housing components of the lubricant housing. Further preferably, at least one of the welded joints provided for connecting two metallic housing components of the lubricant housing is circumferentially interrupted at at least one location. An elastomer seal, for example an O-ring, is arranged between the metallic housing components to be connected for sealing purposes.The interrupted welded joint and the elastomer seal then enable a diffusion process into and out of the lubricant chamber. This design of the gas injector is particularly preferred because the seal, made of elastomer material, is arranged between two metal housing components of the lubricant housing and is essentially covered by the welded joint. Direct contact between the elastomer seal and the injected gas only occurs in the area of ​​the interrupted welded joint.

[0020] For example, if the elastomer housing component is the plug, this opening in the lubricant housing can also be used to fill the lubricant chamber with liquid lubricant and gas.

[0021] Preferably, the gas pressure of the gas in the lubricant chamber is between atmospheric pressure and a pressure of 4 x 10 5 Pa.

[0022] The liquid lubricant is preferably a mineral oil, a synthetic oil, a silicone oil, or a perfluoropolyether, especially Fonbilin, or any mixture of the above. More preferably, the liquid lubricant contains an antifoam additive that prevents foaming.

[0023] The gas in the lubricant chamber is preferably ambient air or nitrogen or an inert gas, such as helium, neon or argon.

[0024] The gas injector preferably has a vertical or substantially vertical installation position in an internal combustion engine. The installation position of the gas injector is preferably within a range of ± 20° to the vertical, in particular ± 10° to the vertical. The selection of the liquid lubricant depends in particular on the type of lubricant housing, in particular its materials, the specific solubility of the selected gas in the lubricant chamber, the cavitation resistance and / or shear strength of the liquid lubricant, the lubricity, the viscosity, the viscosity index, and / or the thermal expansion coefficient of the liquid lubricant.

[0025] The gas selection is preferably matched to a type of design of the lubricant housing as well as the design of the lubricant housing and the selected liquid lubricant.

[0026] The gas injector is further preferably configured to inject a gas into a combustion chamber of an internal combustion engine.

[0027] Short description of the drawings

[0028] An embodiment of the invention will be described in detail below with reference to the accompanying drawings. In the drawing:

[0029] Figure 1 is a schematic sectional view of a gas injector according to a first embodiment of the invention, and

[0030] Figure 2 is a schematic, enlarged partial sectional view of the

[0031] Gas injector from Figure 1.

[0032] 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.

[0033] As can be seen from Figure 1, the gas injector 1 for injecting a gaseous fuel into a combustion chamber 12 comprises a magnetic actuator 2. The magnetic actuator 2 is configured to move an outwardly opening closure element 3 from a closed state to an open state. Figures 1 and 2 show the closed state of the gas injector 1.

[0034] The magnetic actuator 2 comprises an armature 20, an inner pole 21 and a coil 22. The closing element 3 comprises a valve needle 30 and an armature bolt 23.

[0035] The anchor 20 is attached to the anchor bolt 23.

[0036] The valve needle 30 and the armature pin 23 are loosely in contact with each other at adjacent end faces, so that the armature pin 23 and the valve needle 30 can move independently of each other. The valve needle 30 comprises a plate-shaped sealing element 300, which closes the gas injector 1 at a sealing seat 11.

[0037] The gas injector 1 further comprises a main body 7 with a gas inlet 70 through which the gaseous fuel is supplied to the gas injector. The gas inlet 70 is introduced into the main body in an axial direction XX of the gas injector. The main body 7 is connected to a valve housing 8 in which the magnetic actuator 2 is arranged. The valve housing 8 also serves as a magnetic return element for the magnetic actuator 2.

[0038] A housing sleeve 19 adjoins the valve housing 8 in the axial direction XX. The sealing seat 11 is formed at the end of the housing sleeve 19 facing the combustion chamber.

[0039] Reference numeral 13 denotes an electrical connection, which is only shown schematically in Figure 1 and is routed through the main body to the magnetic actuator 2. The electrical connection 13 serves to supply power to the magnetic actuator.

[0040] To reset an opened closing element, the gas injector 1 further comprises a reset element 10. In this embodiment, the reset element 10 is a cylinder spring which returns the closing element 3 to the closed position shown in Figure 1 after the opening process.

[0041] A gas flow passing through the gas injector 1 is schematically illustrated as gas path 14 in Figure 1. The gas path 14 runs from the gas inlet 70 inside the housing components of the gas injector to the sealing seat 11. The gas path 14 runs outside the magnetic actuator 2. The gas injector 1 further comprises a lubricant chamber 4. The lubricant chamber 4 is a sealed chamber partially filled with a liquid lubricant 47, e.g., oil or the like, and a gas 46 of a damping device 6.

[0042] As can be seen from Figure 1, a lubricant housing 400 of the lubricant chamber 4 is defined by a first flexible sealing element 40 in the form of a bellows, a first sleeve 41, the inner pole 21 and a second sleeve 42. The second sleeve 42 is cup-shaped.

[0043] The flexible sealing element 40 is firmly connected to the valve needle 30 and is preferably a metal bellows. The flexible sealing element 40 ensures axial mobility of the valve needle 30.

[0044] In the components of the lubricant chamber or in components which are arranged in the lubricant chamber, through openings not shown in Figure 1 are provided so that a fluid distribution within the lubricant chamber from an end on the combustion chamber side to an end lying in the direction of the gas inlet 70 is possible.

[0045] The lubricant housing 400, as shown in Figure 2, comprises a plurality of metallic housing components 401, 402, 403, which are connected to one another by weld seams 44. An opening is provided in the metallic housing component 401, which is closed by a sealing plug 48 made of an elastomer. Since the sealing plug 48 is made of an elastomer material, the diffusion of hydrogen into and, in particular, out of the lubricant chamber 4 is significantly simplified. Although hydrogen can also diffuse through metallic components, the diffusion of hydrogen through metallic components is significantly lower than through elastomer components.

[0046] The weld seam 44 between the metallic housing component 402 and the metallic housing component 403 has an interruption 44a. This is shown schematically in Figure 2. The two metallic housing components 402 and 403 overlap in the axial direction XX, with an elastomer O-ring 49 provided radially between the metallic components 402 and 403 for sealing. The interruption 44a in the weld seam 44 ensures improved strength of the welded connection. Due to the interruption, the O-ring 49 then enables sealing between the two housing components 402 and 403.

[0047] It should be noted that instead of the closure plug 48 at the end of the lubricant chamber 4 facing away from the combustion chamber, a flat seal can also be provided between two overlapping flat areas of housing components of the lubricant housing 400.

[0048] As can be seen in detail from Figure 2, a vertical or substantially vertical arrangement of the gas injector 1 can ensure that the gas collects in the region of the lubricant chamber 4 which is remote from the sealing seat 11 and on which the closure plug 41 is arranged.

[0049] The function of the gas injector 1 according to the invention is as follows:

[0050] When the gas injector is opened, the armature 20 is pulled in the direction of the inner pole 21 and in doing so overcomes an armature gap 24. Since the armature 20 is firmly connected to the armature bolt 23, the armature bolt also moves in the direction of the sealing seat 11. Since the armature bolt, in the closed state, rests directly against the valve needle 30 on the side facing the combustion chamber, the valve needle 30 is also moved in the axial direction XX and opens at the sealing seat 11. The gas injector of the first embodiment is thus an outward-opening gas injector.

[0051] Thus, gas injection begins.

[0052] During the opening and closing process, the valve needle 30 is guided on two needle guides 31, 32 on the housing sleeve 19.

[0053] When the gas injection is terminated, the current supply to the magnetic actuator 2 is discontinued, so that the closing element 3 is returned to its closed position shown in Figure 1 by the restoring force of the restoring element 10. To prevent the valve disk from striking the sealing seat 11 too hard, the damping device 6 is provided. The damping device 6 comprises the gas 46, which is arranged in the lubricant chamber 4 in addition to the liquid lubricant 47. During the closing process, the lubricant 47 is set in motion, and the movement of the closing element is dampened by fluid resistance.

[0054] Thus, no additional bellows need to be provided at the end of the lubricant chamber 4 facing away from the sealing seat 11, which significantly reduces the costs of the gas injector 1. The gas injector 1 thus comprises only one metallic bellows 40, which is directly connected to the closing element 3, in particular the valve needle 30.

[0055] By only partially filling the lubricant chamber 4 with liquid lubricant 47, thermally induced changes in the length of components of the gas injector, in particular of the closing element, as well as thermal expansion of the lubricant 47 can be compensated.

[0056] A ratio of liquid to gas is preferably in the range of 70 vol% / 30 vol% to 95 vol% / 5 vol%.

[0057] This simplification of the gas injector allows for the realization of a very cost-effective and robust gas injector with a lubrication option for moving parts.

Claims

Claims 1. A gas injector for injecting a gaseous fuel, comprising: a magnetic actuator (2) with an armature (20), an inner pole (21), and a coil (22); a closing element (3) with a valve needle (30) and an armature pin (23), wherein the valve needle (30) opens and closes a gas path (14) at a sealing seat (11) arranged at a first end of the gas injector; wherein the armature (20) is connected to the armature pin (23), and the armature pin (23) is operatively connected to the valve needle (30); a sealed lubricant chamber (4) filled with a lubricant and in which the armature (20) and the armature pin (23) are arranged; wherein the lubricant provides a lubricating effect in the lubricant chamber (4); a return element (10) which returns the closing element (3) to a closed initial position;wherein the lubricant chamber (4) is filled with a gas and a liquid lubricant for damping movements of the closing element (3), and wherein a ratio of the liquid to the gas is in a range from 70 Vol% / 30 Vol% to 95 Vol% / 5 Vol%., 2. Gas injector according to claim 1, wherein the lubricant chamber (4) has a lubricant housing (400) which comprises a plurality of housing components, wherein exactly one housing component is a metallic bellows which is in operative connection with the closing element (3).

3. Gas injector according to claim 2, wherein several housing components of the lubricant housing (400) are made of metal, in particular steel.

4. Gas injector according to claim 3, wherein the metallic housing components are connected to one another by means of welded joints (44).

5. Gas injector according to claim 4, wherein at least one welded connection has an interruption (44a), wherein a seal between the two housing components is effected by means of a seal, in particular an O-ring (42).

6. Gas injector according to one of the preceding claims, wherein at least one housing component of the lubricant housing (400) is made of an elastomer material.

7. Gas injector according to claim 6, wherein the housing component made of elastomer material is a closure plug (41) or a flat seal.

8. Gas injector according to one of claims 1 to 5, wherein all housing components of the lubricant housing (400) are made of metal.

9. Gas injector according to one of the preceding claims, wherein a pressure of the gas in the lubricant chamber (4) is in a range from ambient pressure to 4 x 10 5 Pa is lying.

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