Gas injector with reduced temperature at seal seat

Abstract

The present invention relates to a gas injector for injecting a gaseous medium, in particular hydrogen, comprising a closure element (2) for opening and closing a through-opening (3) in a sealing seat (4) of a valve body (6), the closure element (2) comprising a valve needle (20) and a valve disc (21), an actuator (5) for operating the closure element (2), and a number of cooling ribs (7; 71; 72) arranged downstream of the sealing seat (4) in the flow direction of the gas injector.

Description

[Technical Field]

[0001] Background technology The present invention relates to a gas injector for injecting a gaseous fuel, such as hydrogen or methane, directly into the combustion chamber of an internal combustion engine, the gas injector comprising means for reducing the temperature at the sealing seat of the gas injector.

[0002] Gas injectors are known in various configurations from the prior art. The technical requirements for gas injectors are significantly different compared to fuel injectors for liquid fuels. In particular, the lack of lubrication by the liquid fuel and the significantly larger volume of the gaseous medium present problems. This can lead to problems with accurate metering for the injection process. Furthermore, high temperatures occur during operation, particularly in the region of the sealing area between the closing element and the valve seat of the gas injector. Combustion gases reaching the sealing area between the closing element and the valve seat during operation can cause elevated temperatures in the sealing area, which can lead to increased wear and possibly distortion of components. This can lead to leaks, particularly in the seat area.

[0003] Disclosure of the Invention In contrast, the gas injector according to the present invention for injecting a gaseous medium, particularly gaseous hydrogen, with the features of claim 1 has the advantage that the heat introduced into the components by the combustion gases can be reduced by utilizing the temperature reduction of the combustion gases themselves during the injection process. The cooling effect of expansion, which is particularly prevalent when the gas injector is supersonic, allows for a significant temperature reduction. This reduces seat wear at the sealing seat, thereby enabling the gas injector to meet the necessary sealing requirements over its service life, both during operation and at rest. In the latter case, for example, there may be a risk of explosion when combustion gases flow into the exhaust or intake tract of an internal combustion engine. Furthermore, wear due to high temperature loads, particularly on the valve disc, can be reduced, allowing the sealing seat to seal reliably over the service life of the gas injector. This is achieved according to the present invention by the gas injector having a closing element that opens and closes a through-opening in the sealing seat of the valve body. In this case, the closing element comprises the valve needle and the valve disc, which seals against the sealing seat. Furthermore, an actuator for operating the closing element is provided. Furthermore, the gas injector has a number of cooling ribs arranged downstream of the sealing seat in the flow direction of the gas injector. These cooling ribs make it possible to utilize the temperature drop of the combustion gases due to their expansion, since the flow cross section downstream of the sealing seat of the gas injector is significantly increased. This results in effective cooling of the area of ​​the gas injector facing the combustion chamber.

[0004] At a gas flow temperature of approximately 30°C, very low local gas temperatures of approximately -150°C can occur. This cooling capacity can be utilized convectively by using cooling ribs in the gas injector, which are preferably located in the coldest exit area of ​​the combustion gases. This reduces the temperature in the components of the gas injector, particularly the valve disc and valve body, which are oriented towards the combustion chamber and are directly exposed to the hot combustion chamber gases.

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

[0006] Preferably, the cooling ribs are formed on the valve disc. The cooling ribs are preferably arranged on the outer periphery of the valve disc and protrude radially. Therefore, when the gas injectors are open, the combustion gases flow through the intermediate regions between the cooling ribs and in particular cool the cooling ribs, which then cool the valve disc. Since part of the sealing seat of the gas injector is located on the valve disc, the sealing seat is also cooled accordingly.

[0007] Furthermore, cooling ribs are preferably arranged on the valve body of the gas injector, on which the second part of the gas injector sealing seat is located, thus also creating a cooling effect, which reduces wear on the components of the gas injector sealing seat.

[0008] Preferably, both the valve disc and the valve body are provided with cooling ribs, so that both components, between which the sealing seat is formed, can simultaneously be cooled in the region of the sealing seat.

[0009] Preferably, the cooling ribs are arranged on the additional component, which allows the components of the valve disc and the valve body that form the sealing seat to be geometrically designed optimally for a reliable seal and can be cooled by the additional component, which is preferably arranged on the valve disc and / or the valve body.

[0010] More preferably, the additional component comprises a core region, which may be hollow, have a vacuum, or be filled with nitrogen or a gas, or alternatively, the core region comprises an insert member.

[0011] According to a further preferred embodiment of the invention, the additional component is a component with a high porosity. The high porosity allows the surface area of ​​the additional component to be increased, which in combination with the cooling ribs provides a significantly larger area on which the valve disc and / or valve body can be cooled. The additional component is preferably a sintered component.

[0012] Furthermore, the valve disc and / or the valve body are preferably provided with an insulating layer, which is preferably formed on the valve disc over its entire side facing the combustion chamber, and which is preferably arranged in the areas of the gas injector where the cooling ribs are not formed.

[0013] Preferably, the insulating layer is also provided on the cooling ribs.

[0014] More preferably, an insulating layer is also provided on the valve body. The insulating layer is preferably applied by material connection, for example by welding or thermal spraying. Preferably, a phase change material is also used, which is capable of absorbing a relatively large amount of heat by phase change during the maximum temperature range in the combustion chamber of an internal combustion engine.

[0015] Instead of a material-tight connection, the additional component can also be attached to the valve disc and / or valve body by a friction-tight connection.

[0016] More preferably, the additional component includes a shielding element arranged on the side of the valve disc facing the combustion chamber. The shielding element protects the valve disc from heat from the combustion chamber. The shielding element is preferably connected to the valve disc by a material-tight connection, for example, by welding. The shielding element may also be provided with an insulating layer or hollow areas, as described above.

[0017] More preferably, the gas injector has a flow-shaping cap disposed on the valve disc for shaping and defining the flow of combustion gas into the combustion chamber. The flow-shaping cap can thus define a suitable flow shape in the combustion chamber to support optimal combustion therein. The flow-shaping cap also has the advantage that the flow can be individually adapted to different internal combustion engines, for example, internal combustion engines from different manufacturers. This allows the gas injector to be manufactured as a mass-produced product, and the flow can then be customized by the flow-shaping cap.

[0018] Preferably, the cooling ribs extend parallel to the central axis of the gas injector. Intermediate spaces between adjacent cooling ribs are preferably open towards the combustion chamber.

[0019] The gas injector is preferably an outward opening injector, where temperature issues are important due to the proximity of the combustion chamber in the case of direct injection.

[0020] Preferably, the gas injector further comprises first and second needle guides for the closing element. In this case, the first needle guide is axially farther from the sealing seat than the second needle guide. The second needle guide is thus arranged closer to the valve disc and is likewise protected from high combustion chamber temperatures by the present invention. This ensures excellent guiding behavior during the opening and closing strokes of the gas injector over its entire service life, which in particular ensures that the planned injection quantity is always achieved reliably.

[0021] In a preferred embodiment of the invention, the valve disk of the closure element and the valve needle are formed in one piece, which has the advantage that it is not necessary to connect the valve disk to the valve needle by welding or the like, which, if connected incorrectly by welding, could potentially lead to distortion of the valve disk and thus to an inconsistent sealing of the sealing seat.

[0022] Furthermore, the invention relates to an internal combustion engine, in particular a vehicle internal combustion engine, equipped with a gas injector according to the invention.

[0023] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings. [Brief explanation of the drawings]

[0024] [Figure 1] 1 is a schematic cross-sectional view showing a gas injector according to a first preferred embodiment of the present invention in a closed state; [Figure 2] 2 is a schematic cross-sectional view showing the seal seat of the gas injector of FIG. 1 in an open state. [Figure 3] 3 is a schematic cross-sectional view showing the combustion chamber side end of the gas injector of FIG. 2 taken along line III-III. FIG. [Figure 4] FIG. 6 is a schematic partial cross-sectional view showing the combustion chamber side end of a gas injector according to a second embodiment of the present invention. [Figure 5] FIG. 5 is a schematic cross-sectional view taken along line VV in FIG. 4. [Figure 6] FIG. 10 is a schematic partial cross-sectional view of a combustion chamber side of a gas injector according to a third embodiment of the present invention. [Figure 7] FIG. 7 is a schematic cross-sectional view taken along line VII-VII in FIG. 6. [Figure 8] FIG. 10 is a schematic partial cross-sectional view of a combustion chamber side of a gas injector according to a fourth embodiment of the present invention. [Figure 9] FIG. 10 is a schematic partial cross-sectional view of a combustion chamber side of a gas injector according to a fifth embodiment of the present invention. [Figure 10]FIG. 10 is a schematic partial cross-sectional view of a combustion chamber side of a gas injector according to a sixth embodiment of the present invention. [Figure 11] FIG. 10 is a schematic partial cross-sectional view of a combustion chamber side of a gas injector according to a seventh embodiment of the present invention. [Figure 12] FIG. 12 is a schematic cross-sectional view taken along line XII-XII in FIG. [Figure 13] FIG. 13 is a schematic partial cross-sectional view of a combustion chamber side of a gas injector according to an eighth embodiment of the present invention.

[0025] Preferred embodiments of the invention A gas injector 1 according to a first preferred embodiment of the present invention will now be described in detail with reference to FIGS.

[0026] As is apparent from FIG. 1, a gas injector 1 for injecting a gaseous medium, in particular gaseous hydrogen, comprises a closing element 2 and an actuator 5 .

[0027] The closing element 2 releases and closes the through-opening 3 in the sealing seat 4. A return element 8 returns the closing element 2 to the closed starting position, which in this case is shown in Figure 1, from which the opening process of the gas injector 1 takes place.

[0028] The closure element 2 comprises a valve needle 20 and a valve disc 21. In this case, the valve needle 20 extends through the gas injector 1 in an axial direction XX.

[0029] The sealing seat 4 is formed between the valve disc 21 and the valve body 6. In this case, the closure element 2 is an outward-opening closure element. The closure element 2 further comprises two needle guides 22 that guide the closure element in the valve body 6.

[0030] The actuator 5 is in this embodiment a magnetic actuator and includes a mover 50 movable in the axial direction XX of the gas injector to bring the closure element 2 from the closed position shown in FIG. 1 to the open position shown in FIG. 2.

[0031] A spring seat 23 is further arranged on the closing element 2, which supports a return element 8 for returning the closing element 2 to the closed position. The return element 8 is a cylindrical spring supported between the spring seat 23 and a step 80 on the valve body 6.

[0032] The gas injector 1 further has a number of cooling ribs 7 arranged downstream of the sealing seat 4 in the direction of flow through the gas injector. In this embodiment, the cooling ribs 7 are arranged only on the closing element 2. More specifically, the cooling ribs 7 are arranged on the valve disc 21 along its outer periphery. In this case, the cooling ribs are formed integrally with the valve disc 21 and open towards the combustion chamber 10. In this case, the gas flow can pass between the cooling ribs 7 in the open state of the gas injector, as shown in FIG. 2.

[0033] 3, it can be seen that the cooling ribs 7 are formed evenly around the circumference of the valve disc 21 at the end of the valve disc 21 facing the combustion chamber. In this case, the cooling ribs 7 extend from the conical portion of the valve disc 21 to the end of the valve disc 21 facing the combustion chamber.

[0034] The expansion of the volume caused by the intermediate regions 7a between the cooling ribs 7 therefore already leads to a considerable expansion of the combustion gases in the region of the valve disc 21. This expansion of the combustion gases results in a cooling effect which is transferred by convection to the surrounding components, in particular to the cooling ribs 7 and the intermediate regions 7a. This results in a decrease in the temperature of the valve disc 21, in particular in the region of the sealing seat 4, which makes it possible to avoid excessive wear on the sealing seat during operation of the gas injector.

[0035] Thus, during operation of the gas injector 1, a temperature drop can be achieved at the sealing seat 4, which significantly reduces the temperature load on the components at the sealing seat 4. This allows the gas injector to be positioned as close as possible to the combustion chamber 10 of the internal combustion engine, thereby enabling direct injection of gaseous fuel into the combustion chamber.

[0036] 1, the gas supply through the gas injector 1 is indicated by arrow A. Arrow B shows diagrammatically the combustion gases exiting the gas injector, resulting in a hollow cone-shaped spray that is injected into the combustion chamber 10 due to the shape of the valve disc 21.

[0037] 4 and 5 show a gas injector 1 according to a second preferred embodiment of the present invention, in which the same or functionally identical parts as those in the first embodiment are given the same reference numerals.

[0038] As can be seen from FIGS. 4 and 5, in the second embodiment, the cooling ribs 71 are arranged only on the valve body 6. The valve disc 21 does not have any cooling ribs. The cooling ribs 71 on the valve body 6 are arranged, in this case, at the end of the valve body 6 facing the combustion chamber, in such a way as to allow a flow of air from the inside to the outside of the valve body 6. Therefore, in the plan view of the valve body 6 (FIG. 5), a castellated (serrated) structure results, in which the cooling ribs 71 are relatively thin in order to provide the largest possible opening cross section through the intermediate space between the cooling ribs 71. This embodiment is particularly suitable for injecting large amounts of gas. In other respects, this embodiment corresponds to the first embodiment, and reference is made to the description given there.

[0039] 6 and 7 show a gas injector according to a third embodiment of the invention, in which elements that are the same or functionally the same as in the previous embodiments are again given the same reference numerals.

[0040] As can be seen from Fig. 6, in the third embodiment, the cooling ribs 72 are arranged on the additional component 11. The additional component 11 is fixed to the valve body 6 by a welded joint 12. The additional component 11 has a core region 11a and an outer periphery region 11b. The cooling ribs 72 are formed between the core region 11a and the outer periphery region 11b. In this case, the additional component 11 is preferably formed integrally.

[0041] The additional component 11 thus reduces the temperature of the gaseous fuel at the combustion chamber end of the gas injector when it exits. In this case, the valve body 6 is directly connected to the additional component 11, which improves cooling of the valve body 6 in particular. The additional component 11 in this embodiment is a disk. It should be noted, however, that the geometry of the additional component 11 can also be configured differently. In other respects, this embodiment corresponds to the previous embodiment, and reference is made to the description given there.

[0042] 8 shows a gas injector 1 according to a fifth embodiment of the present invention. Elements that are the same as or functionally the same as those in the previous embodiments are given the same reference numerals.

[0043] As can be seen in FIG. 8 , the fifth embodiment essentially corresponds to the third embodiment, except that the cooling ribs 71 are arranged on the valve body 6. Furthermore, the closure element 2 is provided with an additional component 11 on the valve disc 21. The additional component 11 includes a pot-shaped casing 13 welded to the combustion chamber-side end of the valve disc 21. A cavity 14 is provided between the pot-shaped casing 13 and the valve disc 21. The cavity 14 serves to provide insulation and can be formed, for example, as a vacuum or filled with a gas, such as nitrogen or air. Alternatively, the cavity 14 can be filled with a porous material or another material with good insulating properties. Thus, in the fifth embodiment, on the one hand, the cooling of the valve body 6 is achieved by the cooling ribs 71, and on the other hand, the introduction of excessive heat into the closure element 2 is prevented by the additional component 11 with the cavity 14. In other respects, this embodiment corresponds to the previous embodiment, and reference is made to the description therein.

[0044] 9 shows a gas injector 1 according to a fifth embodiment of the present invention. Elements that are the same as or functionally the same as those in the previous embodiments are given the same reference numerals.

[0045] As can be seen in FIG. 9 , the closing element 2 includes an additional component 15 arranged on the valve disc 21, which is made of a highly porous material. The additional component 15 is, for example, sintered metal. The additional component 15 covers the entire surface of the valve disc 21 facing the combustion chamber 10. This increases the heat transfer resistance on the side of the valve disc 21 facing the combustion chamber. This reduces the thermal load on the valve disc 21 in the area of ​​the sealing seat 4. The valve body 6 is provided with cooling ribs 71, similar to those in the embodiments of FIGS. 5 and 8 . The additional component 15, like the cooling ribs 71, is located in the expansion area of ​​the gaseous fuel to be injected, so that a cooling effect is also generated for the additional component 15 and the valve disc 21. In other respects, this embodiment corresponds to the previous embodiment, and reference is made to the description therein.

[0046] 10 shows a gas injector 1 according to a sixth embodiment of the present invention. Elements that are the same as or functionally the same as those in the previous embodiments are given the same reference numerals.

[0047] As can be seen in Figure 10, the gas injector of the sixth embodiment has, as an additional component, a shield element 16 fixed to the side of the valve disc 21 facing the combustion chamber. The shield element 16 is fixed to the valve disc 21 by a welded connection 17. The shield element 16 protects the valve disc 21 from the extremely high temperatures from the combustion chamber 10. The valve body 6 is formed with cooling ribs 71, as in the embodiments of Figures 5, 8, and 9. The shield element 16 is mushroom-shaped and includes a planar shielding body having a diameter corresponding to the maximum diameter of the valve disc 21 and legs for connecting to the valve disc 21. In other respects, this embodiment corresponds to the previous embodiments, and reference is made to the description therein.

[0048] 11 and 12 show a gas injector 1 according to a seventh embodiment of the present invention, in which elements that are the same or functionally the same as in the previous embodiments are again given the same reference numerals.

[0049] As can be seen in FIG. 11, the gas injector of the seventh embodiment has an additional component 18 with an open hollow area 18a. The hollow area 18a is open on four sides toward the combustion chamber 10 (see FIG. 12). Therefore, the hollow area 18a has a cross-shaped configuration. The additional component 18 with the hollow area again serves to shield the valve disc 21 in order to reduce its temperature during operation. In this case, the additional component 18 completely covers the side of the valve disc 21 facing the combustion chamber. Such measures for reducing the temperature of the valve disc 21 have the particular advantage that they can be implemented simply and inexpensively. In other respects, this embodiment corresponds to the previous embodiment, and reference is made to the description therein.

[0050] 13 shows a gas injector 1 according to an eighth embodiment of the present invention. Elements that are the same as or functionally the same as those in the previous embodiments are given the same reference numerals.

[0051] As can be seen in Fig. 13, the gas injector 1 of the eighth embodiment has cooling ribs 7 on the valve disc 21 and cooling ribs 71 on the valve body 6. Therefore, the expanding gaseous combustion gas can simultaneously reduce the temperature of both the valve disc 21 and the valve body 6. This achieves particularly good thermal protection of the sealing seat 4 between the valve disc 21 and the valve body 6. Additionally, an insulating layer 9 is provided on the side of the valve disc 21 facing the combustion chamber 10. The insulating layer 9 insulates the valve disc 21 from the hot combustion gases from the combustion chamber 10.

[0052] It should be noted that in all the above embodiments, such an insulating layer 9 can be provided on the valve disc 21 or on an additional component.

[0053] Therefore, in the eighth embodiment, the heat resistance of the components of the gas injector facing the combustion chamber can be significantly improved by arranging the cooling ribs twice on the valve disc 21 and the valve body 6. In other respects, this embodiment corresponds to the previous embodiments, and therefore reference can be made to the descriptions therein.

[0054] It should be noted that for all described embodiments, any combination of the features shown in the embodiments is possible. In particular, to enable insulation from the combustion chamber, an insulating layer may always be provided on the valve disc 21 and / or the valve body 6, or on the additional component, if present. Furthermore, in all embodiments, a shielding element may be arranged on the valve disc 21 or the additional component. In this case, the shielding element may be closed and have a hollow area that is filled with a vacuum or gas or with a solid material, in particular a sintered material. In all embodiments, cooling ribs may be provided only on the valve disc 21 or the valve body 6, or on both components.

Claims

1. 1. A gas injector for injecting a gaseous medium, in particular hydrogen, comprising: a closure element (2) for opening and closing the through-opening (3) at the sealing seat (4) of the valve body (6), the closure element (2) comprising a valve needle (20) and a valve disc (21); an actuator (5) for operating the closure element (2); a plurality of cooling ribs (7; 71; 72) arranged downstream of the sealing seat (4) in the flow direction of the gas injector; a gas injector having

2. 2. The gas injector according to claim 1, wherein the cooling ribs (7; 71; 72) are arranged on the valve disc (21) and / or on the valve body (6).

3. 3. The gas injector according to claim 1, wherein the cooling ribs are arranged on an additional component, and the additional component is arranged on the valve body and / or the valve disc.

4. 4. The gas injector according to claim 3, wherein the additional component has a core region (11a), the core region (11a) being hollow and being filled with a vacuum or a gas, or being filled with an insert member.

5. 5. A gas injector according to claim 3 or 4, wherein the additional component has a high porosity, in particular is a sintered component.

6. 6. The gas injector according to claim 1, wherein an insulating layer (9) is arranged on the valve disc (21) and / or on the valve body (6), the insulating layer facing the combustion chamber (10).

7. 7. The gas injector according to claim 3, wherein the additional component comprises a shield member (16) arranged on a side of the valve disc (21) facing the combustion chamber (10), the shield member (16) insulating the valve disc (21) from heat from the combustion chamber (10).

8. 8. The gas injector according to claim 1, further comprising a flow-shaping cap arranged on the valve disc for shaping the injection flow into the combustion chamber.

9. 9. The gas injector according to claim 1, wherein the closure element is an outwardly opening closure element.

10. 10. The gas injector according to claim 1, wherein the cooling ribs extend parallel to a central axis (XX) of the gas injector.

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