Gas injector with reduced temperatures in the sealing seat

Abstract

The invention relates to a gas injector for injecting a gaseous medium, in particular hydrogen, comprising a closure element (2) which opens and closes a through-opening (3) in a sealing seat (4) of a valve body (6), wherein the closure element (2) comprises a valve needle (20) and a valve disc (21), an actuator (5) for actuating the closure element (2), and a plurality of cooling ribs (7; 71; 72) which are arranged after the sealing seat (4) in the through-flow direction of the gas injector.

Description

[0001] Description

[0002] title

[0003] Gas injector with reduced temperatures at the sealing seat

[0004] State of the art

[0005] The present invention relates to a gas injector for injecting a gaseous fuel, e.g. hydrogen or methane or the like, directly into a combustion chamber of an internal combustion engine with temperature-reducing measures at the sealing seat of the gas injector.

[0006] Gas injectors are known from the prior art in various designs. Compared to fuel injectors for liquid fuels, the technical requirements for gas injectors are significantly different. In addition to the lack of lubrication from a liquid fuel, a significantly larger volume of the gaseous medium is particularly problematic. This can result in problems with the precise metering for an injection process. Furthermore, high temperatures arise during operation, particularly in the sealing area between a closing element and a valve seat of the gas injector. The combustion gases during operation, which reach the sealing area between the closing element and the valve seat, can result in increased temperatures in the sealing area, which leads to increased wear and possibly increased distortion of the components. This can cause leaks in the seat area in particular.

[0007] Disclosure of the invention

[0008] The gas injector according to the invention for injecting a gaseous medium, in particular for injecting gaseous hydrogen, with the features of claim 1, has the advantage that heat input to the components by combustion gases can be reduced by utilizing a temperature reduction of the fuel gas itself during the injection process. Due to the cooling effect through expansion, which is particularly present to a large extent in the case of supersonic outflow from the gas injector, there is a large temperature reduction potential, which can be utilized according to the invention. This results in reduced seat wear on the sealing seat, so that the necessary sealing requirements can be met over the service life of the gas injector both during operation and when stationary. When stationary, for example, there may be a risk of explosion if fuel gas enters the exhaust tract or the intake tract of the internal combustion engine.Furthermore, wear due to high temperature loads, in particular on a valve plate, can be reduced, whereby the sealing seat seals reliably over the service life of the gas injector. This is achieved according to the invention in that the gas injector comprises a closing element which opens and closes a through-opening on a sealing seat of a valve body. The closing element comprises a valve needle and a valve plate, wherein the valve plate seals at the sealing seat. Furthermore, an actuator is provided for actuating the closing element. Furthermore, the gas injector comprises a plurality of cooling fins which are arranged downstream of the sealing seat in the flow direction of the gas injector. The cooling fins enable the temperature reduction of the fuel gas due to the expansion of the fuel gas to be utilized, since the flow cross-section downstream of the sealing seat of the gas injector increases significantly.This ensures effective cooling of the areas of the gas injector facing the combustion chamber.

[0009] At a gas inlet temperature of approximately 30°C, very low gas temperatures of up to approximately -150°C can occur locally. This cooling potential can be utilized convectively by using the cooling fins on the gas injector, which are preferably located in the coolest outflow areas of the fuel gas. This reduces the temperatures on the gas injector components facing the combustion chamber and directly exposed to the hot combustion chamber gases, particularly the valve plate and valve body.

[0010] The subclaims disclose preferred developments of the invention. The cooling fins are preferably formed on the valve plate. The cooling fins are preferably arranged on an outer circumference of the valve plate and protrude radially. Thus, when the gas injector is open, the fuel gas flows through the intermediate regions between the cooling fins and, in particular, cools the cooling fins, which in turn cool the valve plate. Since part of the sealing seat of the gas injector is located on the valve plate, the sealing seat is also cooled accordingly.

[0011] Cooling fins are also preferably arranged on the valve body of the gas injector. Since a second part of the gas injector's sealing seat is located on the valve body, a cooling effect is also created here, which reduces wear on the components of the gas injector's sealing seat.

[0012] Preferably, cooling fins are formed on both the valve plate and the valve body so that both components, between which the sealing seat is formed, can be cooled in the region of the sealing seat at the same time.

[0013] The cooling fins are preferably arranged on an additional component. This allows the components of the valve plate and valve body that form the sealing seat to be optimally designed for a secure seal, and cooling can be achieved via the additional component. The additional component is preferably arranged on the valve plate and / or the valve body.

[0014] More preferably, the additional component comprises a core region. The core region can be hollow and have a vacuum or be filled with nitrogen or a gas, or alternatively, the core region has an insert.

[0015] According to a further preferred embodiment of the invention, the additional component is a component with high porosity. Due to the high porosity, the surface area of ​​the additional component can be increased, so that, in conjunction with the cooling fins, a very large area is available that can cool the valve disk and / or the valve body. The additional component is preferably a sintered component.

[0016] Further preferably, an insulating layer is provided on the valve plate and / or the valve body. The layer is preferably completely formed on the valve plate on the side of the valve plate facing the combustion chamber. The insulating layer is preferably arranged in the areas of the gas injector where no cooling fins are formed.

[0017] Preferably, the insulation layer is also provided on the cooling fins.

[0018] More preferably, the insulation layer is also provided on the valve body. The insulation layer is preferably applied by means of a material bond, for example, by welding or flame spraying or the like. Preferably, a phase-change material is also used, which, through phase transition, can absorb a relatively large amount of heat during the highest temperature ranges in the combustion chamber of the internal combustion engine.

[0019] Instead of a material connection, the additional component can also be attached to the valve plate and / or the valve body by means of a force-locking connection.

[0020] The additional component further preferably comprises a shielding element arranged on the side of the valve plate facing the combustion chamber. The shielding element protects the valve plate from heat from the combustion chamber. The shielding element is preferably connected to the valve plate by means of a material connection, for example, a weld. Insulating layers or hollow areas or the like, as described above, can also be provided on the shielding element.

[0021] The gas injector further preferably comprises a jet-shaping cap arranged on the valve plate to shape and define an injection jet of the combustion gas into the combustion chamber. The jet-shaping cap can thus predetermine a preferred jet shape in the combustion chamber to support optimal ignition in the combustion chamber. The jet-shaping cap further has the advantage that the injection jet can be individually adapted for different internal combustion engines, for example internal combustion engines from different manufacturers. This results in the advantage that the gas injector can be manufactured as a mass-produced component and the injection jet can then be customized using the jet-shaping cap. The cooling fins preferably run parallel to a central axis of the gas injector. The spaces between adjacent cooling fins are preferably open towards the combustion chamber.

[0022] The gas injector is preferably an outward-opening injector, where the temperature problem is of great importance in direct injection due to the proximity to the combustion chamber.

[0023] Preferably, the gas injector further comprises a first and a second needle guide for the closing element. The first needle guide is further away from the sealing seat in the axial direction than the second needle guide. The second needle guide is thus arranged close to the valve disk and can also be protected from high combustion chamber temperatures by the invention. As a result, the guidance behavior of the gas injector during the opening and closing process is very good throughout its service life, so that, in particular, the planned injection quantities are always reliably achieved.

[0024] According to a preferred embodiment of the invention, the valve disk and the valve needle of the closing element are formed as a single piece. This has the particular advantage that the valve disk does not need to be connected to the valve needle by a weld or similar joint, which, if the weld is incorrectly placed, could potentially lead to distortion of the valve disk and thus to leakage at the sealing seat.

[0025] Furthermore, the present invention relates to an internal combustion engine, in particular an internal combustion engine of a vehicle, with a gas injector according to the invention.

[0026] drawing

[0027] Preferred embodiments of the invention are described in detail below with reference to the accompanying drawings. In the drawing:

[0028] Figure 1 is a schematic sectional view of a gas injector according to a first preferred embodiment of the invention in the closed state, Figure 2 is a schematic sectional view of a sealing seat of the

[0029] Gas injector of Figure 1 in the open state,

[0030] Figure 3 is a schematic sectional view of the combustion chamber side

[0031] End of the gas injector of Figure 2 along the line lll-lll,

[0032] Figure 4 is a schematic partial sectional view of a combustion chamber side

[0033] End of a gas injector according to a second embodiment of the invention,

[0034] Figure 5 is a schematic sectional view along the line VV of

[0035] Figure 4,

[0036] Figure 6 is a schematic, combustion chamber side partial sectional view of a

[0037] Gas injector according to a third embodiment of the invention,

[0038] Figure 7 is a schematic sectional view along the line VII-VII of

[0039] Figure 6,

[0040] Figure 8 is a schematic, combustion chamber side partial sectional view of a

[0041] Gas injector according to a fourth embodiment of the invention,

[0042] Figure 9 is a schematic, combustion chamber side partial sectional view of a

[0043] Gas injector according to a fifth embodiment of the invention,

[0044] Figure 10 is a schematic, combustion chamber-side partial sectional view of a gas injector according to a sixth embodiment of the invention,

[0045] Figure 11 is a schematic, combustion chamber-side partial sectional view of a gas injector according to a seventh embodiment of the invention, Figure 12 is a schematic sectional view along the line Xll-Xll of Figure 11, and

[0046] Figure 13 is a schematic, combustion chamber-side partial sectional view of a gas injector according to an eighth embodiment of the invention.

[0047] Preferred embodiments of the invention

[0048] 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.

[0049] As can be seen from Figure 1, the gas injector 1 for injecting a gaseous medium, in particular gaseous hydrogen, comprises a closing element 2 and an actuator 5.

[0050] The closing element 2 releases a through-opening 3 at a sealing seat 4 and closes it. A return element 8 returns the closing element 2 to a closed initial position. Figure 1 shows the closed initial position, from which the gas injector 1 opens.

[0051] The closing element 2 comprises a valve needle 20 and a valve plate 21. The valve needle 20 runs in the axial direction XX through the gas injector 1.

[0052] The sealing seat 4 is formed between the valve plate 21 and a valve body 6. The closing element 2 is an outward-opening closing element. The closing element 2 further comprises two needle guides 22, which guide the closing element in the valve body 6.

[0053] In this embodiment, the actuator 5 is a magnetic actuator and comprises an armature 50 which is movable in the axial direction XX of the gas injector in order to move the closing element 2 from the closed position shown in Figure 1 into the open position shown in Figure 2.

[0054] Furthermore, a spring plate 23 is arranged on the closing element 2, against which a return element 8 is supported for returning the closing element 2 to the closed position. The return element 8 is a cylindrical spring, which is supported between the spring plate 23 and a shoulder 80 on the valve body 6.

[0055] The gas injector 1 further comprises a plurality of cooling fins 7, which are arranged downstream of the sealing seat 4 in the flow direction through the gas injector. In this exemplary embodiment, the cooling fins 7 are arranged only on the closing element 2. More precisely, the cooling fins 7 are arranged on the valve plate 21 along the outer circumference of the valve plate 21. The cooling fins are formed integrally with the valve plate 21 and are open toward the combustion chamber 10. A gas flow can flow between the cooling fins 7 when the gas injector is open, as indicated in Figure 2.

[0056] From the sectional view of Figure 3, it can be seen that the cooling fins 7 are formed uniformly along the outer circumference of the valve plate 21 at the combustion chamber-side end of the valve plate 21. The cooling fins 7 extend from a conical part of the valve plate 21 to the combustion chamber-side end of the valve plate 21.

[0057] The resulting volume increase due to the intermediate regions 7a between the cooling fins 7 thus results in a significant expansion of the fuel gas already in the area of ​​the valve plate 21. The expansion of the fuel gas results in a cooling effect of the fuel gas, which is transferred by convection to the surrounding components, in particular to the cooling fins 7 and intermediate regions 7a. This results in a reduction in the temperature of the valve plate 21, particularly in the area of ​​the sealing seat 4, which can prevent excessive wear on the sealing seat during operation of the gas injector.

[0058] Thus, during operation of the gas injector 1, a temperature reduction at the sealing seat 4 can be achieved, which significantly reduces the temperature load on the components at the sealing seat 4. This makes it possible for the gas injector to be arranged as close as possible to the combustion chamber 10 of the internal combustion engine, enabling direct injection of the gaseous fuel into the combustion chamber. In Figure 1, the gas supply through the gas injector 1 is indicated by the arrows A. The arrows B schematically show the outflow of the fuel gas from the gas injector, whereby the shape of the valve plate 21 creates a hollow cone-shaped spray that is injected into the combustion chamber 10.

[0059] Figures 4 and 5 show a gas injector 1 according to a second preferred embodiment of the invention. Identical or functionally identical parts are designated by the same reference numerals as in the first embodiment.

[0060] As can be seen from Figures 4 and 5, in the second embodiment, cooling fins 71 are only arranged on the valve body 6. The valve plate 21 does not have any cooling fins. The cooling fins 71 on the valve body 6 are arranged in such a way that they allow a passage from the inside to the outside of the valve body 6 at the combustion chamber end of the valve body 6. Thus, a plan view (Figure 5) of the valve body 6 results in a crenellated structure, with the cooling fins 71 being relatively thin in order to provide the largest possible opening cross-section through the spaces between the cooling fins 71. This embodiment is particularly suitable for injecting large quantities of gas. Otherwise, this embodiment corresponds to the first embodiment, so that reference can be made to the description given there.

[0061] Figures 6 and 7 show a gas injector according to a third embodiment of the invention. Identical or functionally identical parts are again designated by the same reference numerals as in the previous embodiments.

[0062] As can be seen from Figure 6, in the third exemplary embodiment, cooling fins 72 are arranged on an additional component 11. The additional component 11 is fixed to the valve body 6 by means of a welded connection 12. The additional component 11 has a core region 11a and a peripheral region 11b. The cooling fins 72 are formed between the core region 11a and the peripheral region 11b. The additional component 11 is preferably formed in one piece. The additional component 11 thus reduces the temperature when the gaseous fuel emerges at the combustion chamber end of the gas injector. In particular, the valve body 6 is cooled more effectively because it is directly connected to the additional component 11. The additional component 11 of this exemplary embodiment is a disk. It should be noted, however, that the geometric shape of the additional component 11 can also be designed differently.Otherwise, this embodiment corresponds to the previous embodiments, so that reference can be made to the description given there.

[0063] Figure 8 shows a gas injector 1 according to a fifth embodiment of the invention. Identical or functionally identical parts are designated by the same reference numerals as in the previous embodiments.

[0064] As can be seen from Figure 8, the fifth embodiment essentially corresponds to the third embodiment, with cooling fins 71 being arranged on the valve body 6. Furthermore, an additional component 11 is provided on the closing element 2 on the valve plate 21. The additional component 11 comprises a cup-shaped housing 13, which is welded to the combustion chamber-side end of the valve plate 21. A cavity 14 is provided between the cup-shaped housing 13 and the valve plate 21. The cavity 14 serves for insulation and can, for example, be designed as a vacuum or filled with a gas, for example nitrogen or air. Alternatively, it is also possible for the cavity 14 to be filled with a porous material or another material with good insulating properties.Thus, in the fifth embodiment, cooling of the valve body 6 is achieved by the cooling fins 71, while excessive heat input into the closing element 2 is prevented by the additional component 11 with the cavity 14. Otherwise, this embodiment corresponds to the previous embodiments, so reference can be made to the description given there.

[0065] Figure 9 shows a gas injector 1 according to a fifth exemplary embodiment of the invention. Identical or functionally identical parts are designated by the same reference numerals as in the previous exemplary embodiments. As can be seen from Figure 9, an additional component 15 made of a material with high porosity is arranged on the closing element 2 on the valve plate 21. The additional component 15 is, for example, a sintered metal. The additional component 15 covers the entire surface of the valve plate 21 that is directed towards the combustion chamber 10. This increases the thermal conductivity on the side of the valve plate 21 facing the combustion chamber. This reduces the thermal load on the valve plate 21 in the region of the sealing seat 4. Cooling fins 71 are provided on the valve body 6, similar to the exemplary embodiments of Figures 5 and 8.Since the additional component 15, like the cooling fins 71, is also located in the expansion region of the gaseous fuel to be injected, a cooling effect also results on the additional component 15 and the valve plate 21. Otherwise, this embodiment corresponds to the previous embodiments, so that reference can be made to the description given there.

[0066] Figure 10 shows a gas injector 1 according to a sixth embodiment of the invention. Identical or functionally identical parts are designated by the same reference numerals as in the previous embodiments.

[0067] As can be seen from Figure 10, the gas injector of the sixth embodiment has a shielding element 16 as an additional component, which is fixed to the side of the valve plate 21 facing the combustion chamber. The shielding element 16 is fixed to the valve plate 21 by means of a welded connection 17. The shielding element 16 protects the valve plate 21 from very high temperatures from the combustion chamber 10. Cooling fins 71 are formed on the valve body 6, as in the embodiments of Figures 5, 8, and 9. The shielding element 16 is mushroom-shaped with a flat shield whose diameter corresponds to the maximum diameter of the valve plate 21, and a base for connection to the valve plate 21. Otherwise, this embodiment corresponds to the previous embodiments, so that reference can be made to the description given there.

[0068] Figures 11 and 12 show a gas injector 1 according to a seventh exemplary embodiment of the invention. Identical or functionally identical parts are again designated by the same reference numerals as in the previous exemplary embodiments. As can be seen from Figure 11, the gas injector of the seventh exemplary embodiment has an additional component 18 with an open hollow region 18a. The hollow region 18a is open to the combustion chamber 10 on four sides (cf. Figure 12). The hollow region 18a thus has the shape of a cross. The additional component 18 with the hollow region also serves to shield the valve plate 21 in order to reduce the temperature of the valve plate 21 during operation. The additional component 18 completely covers the surface of the valve plate 21 facing the combustion chamber. This measure for reducing the temperature on the valve plate 21 has the particular advantage of being simple and cost-effective to implement.Otherwise, this embodiment corresponds to the previous embodiments, so that reference can be made to the description given there.

[0069] Figure 13 shows a gas injector 1 according to an eighth embodiment of the invention. Identical or functionally identical parts are designated by the same reference numerals as in the previous embodiments.

[0070] As can be seen from Figure 13, the gas injector 1 of the eighth embodiment has cooling fins 7 on the valve plate 21 and cooling fins 71 on the valve body 6. Thus, a temperature reduction can occur simultaneously on both the valve plate 21 and the valve body 6 due to the expanding gaseous fuel gas. This achieves particularly good temperature protection of the sealing seat 4 between the valve plate 21 and the valve body 6. Additionally, an insulating layer 9 is provided on the side of the valve plate 21 facing the combustion chamber 10. The insulating layer 9 insulates the valve plate 21 from the hot fuel gases from the combustion chamber 10.

[0071] It should be noted that in all the embodiments described above, such an insulating layer 9 can also be provided on the valve plate 21 or the additional component.

[0072] Thus, in the eighth embodiment, the dual arrangement of cooling fins on the valve plate 21 and the valve body 6 allows for significantly improved temperature resistance of the gas injector components facing the combustion chamber. Otherwise, this embodiment corresponds to the previous embodiment, so reference can be made to the description given there.

[0073] With regard to all of the exemplary embodiments described, it should be noted that any desired combination of the features presented in the exemplary embodiments is possible. In particular, an insulating layer can always be provided on the valve plate 21 and / or on the valve body 6 or, if present, on an additional component in order to enable insulation from the combustion chamber. Furthermore, a shielding element can also be arranged on the valve plate 21 or an additional component in all exemplary embodiments. The shielding element can also have a hollow region that is closed off and filled with a vacuum or a gas or is filled with a solid material, in particular a sintered material. In all exemplary embodiments, cooling fins can be provided either only on the valve plate 21 or on the valve body 6 or on both components.

Claims

Claims 1. Gas injector for injecting a gaseous medium, in particular hydrogen, comprising: a closing element (2) which opens and closes a through-hole (3) at a sealing seat (4) of a valve body (6), wherein the closing element (2) comprises a valve needle (20) and a valve disc (21), an actuator (5) for actuating the closing element (2), and a plurality of cooling fins (7; 71; 72) which are arranged in the direction of flow through the gas injector downstream of the sealing seat (4).

2. Gas injector according to claim 1, wherein the cooling fins (7; 71; 72) are arranged on the valve plate (21) and / or on the valve body (6).

3. Gas injector according to one of the preceding claims, wherein the cooling fins (72) are arranged on an additional component (11), wherein the additional component (11) is arranged on the valve body (6) and / or on the valve plate (21).

4. Gas injector according to claim 3, wherein the additional component has a core area (11a) which is hollow and filled with a vacuum or a gas or which is filled with an insert.

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

6. Gas injector according to one of the preceding claims, wherein an insulating layer (9) is arranged on the valve plate (21) and / or on the valve body (6), which is directed towards the combustion chamber (10).

7. Gas injector according to one of claims 3 to 6, wherein the additional component comprises a shielding element (16) which is arranged on a side of the valve plate (21) facing the combustion chamber (10) and shields the valve plate from heat from the combustion chamber (10).

8. Gas injector according to any one of the preceding claims, further comprising a jet-shaping cap arranged on the valve plate (21) to shape an injection jet (B) into the combustion chamber (10).

9. Gas injector according to any one of the preceding claims, wherein the The locking element is an outward-opening locking element.

10. Gas injector according to one of the preceding claims, wherein the cooling fins run parallel to a central axis (XX) of the gas injector.

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