Fuel valve for the metered dispensing of fuel

Abstract

The invention relates to a fuel valve for the metered dispensing of fuel, having a housing (1) which can be filled with a fluid fuel and which has an outlet opening (7). In the housing (1), a valve needle (15) is arranged that can be moved in its longitudinal direction and interacts with a valve seat (17) to open and close the outlet opening (7), wherein the valve needle (15) is surrounded over part of its length by a bellows (30) that seals off an interior space (32). The bellows (30) is connected, at the end facing the outlet opening (7), in a fluid-tight manner to a connection ring (40) that is braced against a sealing seat (41) on the valve needle (15) by a clamping nut (23) surrounding the valve needle (15).

Description

[0001] title

[0002] Fuel valve for metered release of fuel

[0003] The invention relates to a fuel valve as used for the metered release of fuel, in particular gaseous fuel.

[0004] State of the art

[0005] Valves for the metered release of gaseous or liquid fuel are used, for example, to meter fuel into a combustion chamber or the intake tract of an internal combustion engine. It is essential that the correct amount of fuel is introduced at the right time to ensure optimal combustion of the fuel in the combustion chamber. Such a fuel valve is known, for example, from DE 10 2021 200 689 A1 and has a piston-shaped valve element that is moved by an electromagnet, thereby opening and closing a metering opening. The fuel, which in this case is gaseous, flows around the valve element and thus reaches the metering opening. The valve element itself is guided in one or more sections within the housing. To ensure proper functioning, a lubricant is present that wets the guide surfaces of the valve element and thus ensures its mobility.

[0006] To prevent the lubricant from mixing with the fuel, the valve element is located in a lubricant area that is sealed, among other things, by a corrugated bellows that prevents mixing of fuel and lubricant while still allowing longitudinal movement of the valve element. The corrugated bellows is connected to the valve element at both ends via fluid-tight welds, so that the lubricant chamber is hermetically sealed from the fuel. Manufacturing these welds is complex and requires special equipment for series production. Furthermore, assembling the valve element is difficult because it is usually made up of multiple parts, and the corrugated bellows must not be subjected to torsional loads. This makes manufacturing the valve element with welded-on corrugated bellows complex and expensive.

[0007] Disclosure of the invention

[0008] Advantages of the invention

[0009] The fuel valve according to the invention has the advantage that a lubricant chamber or an interior space surrounding the valve element can be sealed off from an exterior space in which the fuel to be metered is guided in a simple and therefore flexible manner. For this purpose, the fuel valve for the metered release of fuel has a housing that can be filled with a fluid fuel and that has an outlet opening. A valve needle is arranged in the housing, which is movable in its longitudinal direction and which interacts with a valve seat to open and close the outlet opening, wherein the valve needle is surrounded over part of its length by a corrugated bellows that seals off an interior space. At the end facing the outlet opening, the corrugated bellows is connected in a fluid-tight manner to a connecting ring, which is clamped against a sealing seat on the nozzle needle by a clamping nut surrounding the valve needle.

[0010] The connecting ring is connected to the bellows in a fluid-tight manner via a welded joint, so that no fluid can escape from the interior of the bellows to the outside at this point. The fluid-tight sealing of the interior is finally achieved by clamping this connecting ring against a sealing seat on the valve needle. Fixing it in place using the connecting ring also allows the valve needle to be dismantled and the bellows to be replaced if necessary, thus providing greater flexibility in the design, maintenance, and repair of such a fuel valve. In the context of this patent application, a fluid is understood to be a gas or a liquid. In a first advantageous embodiment, the clamping nut engages in a thread formed on the outside of the valve needle. This thread is easy to manufacture and can be applied at various points on the valve needle, depending on the installation situation.

[0011] In a further advantageous embodiment, a clamping sleeve is arranged between the connecting ring and the clamping nut. This clamping sleeve also surrounds the valve needle and transfers the pressing force from the clamping nut to the connecting ring. This allows the clamping nut to be positioned at a significant distance from the sealing surface, allowing additional flexibility in design modifications.

[0012] In a further advantageous embodiment, the valve needle forms an outer contour in the area of ​​the clamping sleeve, into which the clamping sleeve engages positively, thus securing it against rotation on the valve needle. This way, the torque of the clamping nut is not transferred to the connecting ring, and no further precautions are required to prevent rotation of the connecting ring and thus possible torsion of the bellows.

[0013] In a further advantageous embodiment, the sealing seat is conical. This enables a good seal and ensures self-centering of the connecting ring on the valve needle. Advantageously, the contact surface on the connecting ring, with which the clamping nut rests on the sealing seat, is also conical.

[0014] In a further advantageous embodiment, the sealing seat is designed as a flat annular surface, and a corresponding flat contact surface is formed on the connecting ring, which also forms an annular surface and with which the connecting ring rests on the sealing seat. Such an annular surface is cost-effective to manufacture and can absorb high pressing forces.

[0015] In a further advantageous embodiment, a sealing ring is arranged between the connecting ring and the nozzle needle. This sealing ring provides additional sealing, thus increasing operational reliability. It can also be provided that the sealing ring fulfills the primary sealing function, while only a partial seal is provided between the connecting ring and the sealing seat. In this case, the sealing seat can be of any shape, i.e., a flat or conical seat with any opening angle.

[0016] In a further advantageous embodiment, the end of the bellows facing away from the outlet opening is sealingly connected to a second connecting ring. The second connecting ring advantageously rests against a shoulder in the housing facing the outlet opening. This creates a seal between the valve needle and the housing to reliably seal the interior, which contains the lubricant or other fuel, from the fuel.

[0017] In a further advantageous embodiment, the interior is filled with a lubricant. This lubricant can wet various areas where the valve needle is guided in the housing, ensuring low-friction movement and thus a long service life.

[0018] drawing

[0019] The drawing shows various embodiments of the fuel valve according to the invention. Figure 1 shows a longitudinal section through a fuel valve according to the invention, with only the essential parts being shown.

[0020] Figure 2 is an enlarged view of the section marked II in Figure 1,

[0021] Figure 3 shows another embodiment in the same representation as Figure 2,

[0022] Figure 4 shows another embodiment of the corrugated bellows seal,

[0023] Figure 5, also a further embodiment of the bellows seal, Figure 5A a cross section through a valve needle according to the invention in the region of the cross-sectional plane designated by A in Figure 5,

[0024] Figure 6 shows another embodiment in the same representation as Figure 2 and

[0025] Figure 7 shows another such embodiment. Description of the embodiments

[0026] Figure 1 shows a fuel valve according to the invention in longitudinal section, with only the essential parts being shown. The fuel valve has a housing 1 comprising a valve body 2 and a jacket tube s, which are connected to one another in a fluid-tight manner by a clamping device not shown in detail in the drawing. Formed inside the valve body 2 is a thread 6, into which a nozzle body 4 is screwed, which protrudes from the valve body 2 at the outlet-side end thereof. The outlet-side end of the nozzle body 4 is surrounded by a valve tube 5, which is fixed between the valve body 2 and the nozzle body 4 by the screw connection on the thread 6. The valve tube 5 serves to shape and direct the ejected fuel, which exits from an outlet opening 7 in the nozzle body 4 into the valve tube 5, wherein preferably gaseous fuel is metered.

[0027] Within the housing 1, a pressure chamber 8 is formed, which can be filled with the liquid or gaseous fuel to be metered under an injection pressure. The pressure chamber 8 is connected to an intermediate space 10 formed between the nozzle body 4 and the valve body 2, and to a nozzle chamber 14 formed in the nozzle body 4. The connections are established via inclined bores 9 in the valve body 2 and via further inclined bores 13 in the nozzle body 4. The fuel in the pressure chamber 8 flows to an outlet opening 7 formed at the outlet-side end of the nozzle body 4.

[0028] A piston-shaped valve needle 15 is arranged inside the nozzle body 4 so that it can be moved longitudinally. At its end facing the outlet end of the housing 1, the valve needle 15 has a valve plate 16 which interacts with a valve seat 17 surrounding the outlet opening 7 to open and close the outlet opening 7. If the valve needle 15 moves in the direction of the outlet opening 7, i.e. downwards in Figure 1, an annular gap between the valve plate 16 and the valve seat 17 is opened and fuel can flow out of the nozzle chamber 14, with the fuel being directed through the valve tube 5. If the valve needle 15 moves into contact with the valve seat 17, the outlet opening 7 is closed again. The nozzle needle 15 extends over the entire length of the nozzle body 4 and is guided in a guide section 20 in the nozzle body 4. An annular space 31 is formed between the nozzle needle 15 and the inner wall of the nozzle body 4.The annular space 31 is connected to the intermediate space 10 via connecting bores 33, so that it is filled with the fuel to be metered during operation of the fuel valve. Alternatively, the fuel can also flow directly around the bellows 30, for example, by the inclined bores 9 opening directly into the annular space 31, eliminating the intermediate space 10 between the nozzle body 4 and the valve body 2.

[0029] The valve needle 15 is surrounded by a corrugated bellows 30, which is arranged inside the nozzle body 4 and, with its end facing the outlet opening 7, is fluid-tightly connected via a first welded joint 35 to a connecting ring 40, which is formed integrally with a clamping sleeve 21 surrounding the valve needle 15. The connecting ring 40 is supported with its outlet-side end on a sealing seat 41 of the valve needle 15, while the opposite end of the clamping sleeve 21 bears against a spring sleeve 22. A thread 19 is formed at the end of the valve needle 15, into which a clamping nut 23 engages, clamping the spring sleeve 22 against the clamping sleeve 21 and thus the connecting ring 40 against the sealing seat 41.

[0030] At its end opposite the first welded joint 35, the corrugated bellows 30 is fluid-tightly connected by a second welded joint 36 to a second connecting ring 50, which is braced against a shoulder 39 in the nozzle body 4 via a support element 26. To set the correct distances, a first adjusting disk 28 is arranged between the second connecting ring 50 and the shoulder 39 formed in the nozzle body 4, and a second adjusting disk 29 is arranged between the support element 26 and the second connecting ring 50. The bracing of the support element 26 is achieved via a clamping screw 37, which engages in a thread inside the nozzle body 4. A valve spring 25 under compressive preload is arranged between the support element 26 and the spring sleeve 22, by means of which the valve needle 15 is pressed against the valve seat 17.If a sufficiently large longitudinal force is exerted on the valve needle 15 by an electrical actuator not shown in the drawing, for example an electromagnet, the latter moves in the longitudinal direction against the force of the valve spring 25 to open the outlet opening 7.

[0031] The corrugated bellows 30 surrounds an interior space 32 that can be filled with a lubricant. The lubricant wets the guide section 24 between the spring sleeve 22 and the support element 26, enabling largely friction-free movement of the valve needle 15. A gap remains between the second connecting ring 50 and the clamping sleeve 21, through which the lubricant can flow. In the area of ​​the support element 26, the flow of lubricant is ensured via through holes 27. The corrugated bellows 30 is flexible in the longitudinal direction, so that movement of the valve needle 15 within the housing 1 is not impeded, but nevertheless the interior space 32 is sealed against the annular space 31 and thus the lubricant is sealed against the fuel.

[0032] Figure 2 shows the section designated II in Figure 1 of a further exemplary embodiment according to the invention, wherein only one half of the fuel valve along the central axis 11 is shown. The end of the corrugated bellows 30 facing the outlet opening 7 is connected to a separate connecting ring 40. The connecting ring 40 surrounds the valve needle 15 and rests with a conical contact surface 44 on a likewise conical sealing seat 41 on the valve needle 15. A fluid-tight welded connection is formed between the corrugated bellows 30 and the connecting ring 40. The clamping nut 23 is arranged here within the corrugated bellows 30 and surrounds the valve needle 15. The clamping nut 23 clamps the connecting ring 40 against the sealing seat 41, engaging in the thread 19 on the valve needle 15, which is also arranged here within the corrugated bellows 30.Since the clamping nut 23 rests directly on the connecting ring 40 here, the clamping sleeve 21 is omitted in this exemplary embodiment. The valve spring 25, not shown here, also acts on the valve needle 15 here, but in a structurally different manner, so that the spring sleeve 22 is also omitted. The contact of the connecting ring 40 on the sealing seat 41 likewise creates a fluid-tight connection, so that the interior space 32 delimited by the bellows 30 is sealed and the lubricant contained therein does not mix with the fuel in the annular space 31. To prevent the valve needle 15 from rotating when the clamping nut 23 is tightened and thus potentially damaging the bellows 30, holding contours 45, 46 can be provided at the ends of the valve needle 15 to hold the valve needle 15 during the screwing process. The holding contours 45, 46 can, for example, be in the form of wrench flats.

[0033] Figure 3 shows a further embodiment of the invention in the same representation as Figure 2. Here, the connecting ring 40 is not preloaded directly against the sealing seat 41 via the clamping nut 23, but rather, as in the embodiment of Figure 1, using a clamping sleeve 21. The clamping sleeve 21 surrounds the valve needle 15 and transfers the force of the clamping nut 23 to the connecting ring 40. This allows the clamping nut 23 to be positioned further away from the connecting ring 40, which improves accessibility to the clamping nut 23 and facilitates assembly. The clamping nut 23 can thus also be arranged outside the corrugated bellows 30.

[0034] Figure 4 shows a further exemplary embodiment of the inventive arrangement of the connecting ring 40'. The connecting ring 40' here has a flat contact surface 44', which rests on an equally flat sealing seat 41'. This design of the connecting ring 41 and the contact surface 44' is simple to manufacture and allows horizontal displacement of the connecting ring 40'. For secure sealing, a sealing ring 48 is additionally provided between the connecting ring 40 and the valve needle 15. It can also be provided that the actual fluid-tight seal is ensured by the sealing ring 48, while the sealing seat 41' serves only as an abutment for the first connecting ring 40'. This results in more freedom in the design of the sealing seat 41' and the contact surface 44'.

[0035] Figure 5 shows a further exemplary embodiment in the same representation as Figure 3. Here, too, the end of the corrugated bellows 30 facing the outlet opening 7 is fluid-tightly connected to the connecting ring 40 via a welded joint 35. A second connecting ring 50 is also provided here to seal the opposite end of the corrugated bellows 30. The second connecting ring 50 is also connected to the corrugated bellows 30 via a welded joint 36 and rests on a shoulder 55 in the nozzle body 4. In addition, a sealing ring 47 is arranged between the second connecting ring 50 and the nozzle body 4 in order to achieve additional sealing of the interior space 32 - similar to the representation in Figure 4. The shoulder 55 is flat, so that the sealing ring 47 optimizes the seal. The clamping force on the connecting ring 40 is also generated here via a clamping sleeve 21 and a clamping nut 23.To prevent the clamping sleeve 21 from rotating when the clamping nut 23 is screwed on, the valve needle 15 has an outer contour 49, into which the clamping sleeve 21 engages with a corresponding inner contour. Figure 5A shows a cross-section through the exemplary embodiment shown in Figure 5 along line A. Since the clamping sleeve 21 and the valve needle 15 interlock, rotation of the clamping sleeve 21 is prevented when the clamping nut 23 is screwed on, in order to prevent a torsional moment from being exerted on the first connecting ring 40. In addition, retaining contours 45, 46 can also be formed on the valve needle 15 to fix it when the clamping nut 23 is screwed on. An interlocking outer and inner contour can also be provided between the connecting ring 40 and the valve needle 15 or between the spring sleeve 22 and the valve needle 15.

[0036] Figure 6 shows a further exemplary embodiment in the same representation as Figure 5. Here, too, the second connecting ring 50 is preloaded against the shoulder 55 by the clamping screw 37, with two adjusting disks 52, 53 being used: A first adjusting disk 52 is arranged between the clamping screw 37 and the second connecting ring 50, and a second adjusting disk 53 is arranged between the second connecting ring 50 and the shoulder 55. This allows the position of the second connecting ring 50 within the nozzle body 4 to be precisely adjusted so that a different preload of the bellows 30 does not reduce or increase the spring force of the valve spring 25. The first adjusting disk 52 and the second adjusting disk 53 do not have to be of the same thickness, as shown in the exemplary embodiment in Figure 7.Without changing the position of the clamping screw 37, the first adjusting disk 52 is thicker than the second adjusting disk 53, the total thickness of the two adjusting disks 52, 53 corresponding to that in Figure 6. Through this configuration of the adjusting disks 52, 53, the second connecting ring 50 is positioned further in the direction of the first connecting ring 40, if necessary. The movement of the valve needle 15 is preferably effected by means of an electromagnet, which is not shown in Figure 1. The valve needle 15 can also be moved by means of another electrical actuator, for example a piezo actuator or a magnetostrictive actuator. A servo-hydraulic movement of the valve needle 15 is also possible.

Claims

Claims 1. Fuel valve for metered dispensing of fuel, comprising a housing (1) which can be filled with a fluid fuel and which has an outlet opening (7), and a valve needle (15) arranged in the housing (1) which is movable in its longitudinal direction and which interacts with a valve seat (17) to open and close the outlet opening (7), wherein the valve needle (15) is surrounded over part of its length by a corrugated bellows (30) which seals an interior space (32), characterized in that the corrugated bellows (30) is fluid-tightly connected at the end facing the outlet opening (7) to a connecting ring (40) which is clamped against a sealing seat (41) on the valve needle (15) by a clamping nut (23) surrounding the valve needle (15).

2. Fuel valve according to claim 1, characterized in that the clamping nut (23) engages in a thread (19) formed on the outside of the valve needle (15).

3. Fuel valve according to claim 1 or 2, characterized in that a clamping sleeve (21) surrounding the valve needle (15) is arranged between the clamping nut (23) and the connecting ring (40), which transmits the pressing force of the clamping nut (23) to the connecting ring (40).

4. Fuel valve according to claim 3, characterized in that the valve needle (15) forms an outer contour (49) in the area of ​​the clamping sleeve (21) into which the clamping sleeve (21) engages in a form-fitting manner, so that the clamping sleeve (21) is secured against rotation about its longitudinal axis.

5. Fuel valve according to one of claims 1 to 4, characterized in that the sealing seat (41) is conical.

6. Fuel valve according to claim 5, characterized in that a conical contact surface (44) is formed on the connecting ring (40) with which the connecting ring (40) rests on the sealing seat (41).

7. Fuel valve according to one of claims 1 to 4, characterized in that the sealing seat (41) is designed as a flat annular surface and a flat contact surface (44)' is formed on the connecting ring (40)', which also forms an annular surface and with which the connecting ring (40)' rests on the sealing seat (41).

8. Fuel valve according to one of claims 1 to 7, characterized in that a sealing ring (48) is arranged between the connecting ring (40) and the nozzle needle (15).

9. Fuel valve according to one of claims 1 to 8, characterized in that the end of the bellows (30) facing away from the outlet opening (7) is sealedly connected to a second connecting ring (50).

10. Fuel valve according to claim 9, characterized in that the second connecting ring (50) rests against a shoulder (55) in the housing (1) facing the outlet opening (7).

11. Fuel valve according to claim 10, characterized in that the second connecting ring (50) is pre-tensioned against the shoulder (55) by a clamping screw (37).

12. Fuel valve according to claim 11, characterized in that a first adjusting disc (51) or a second adjusting disc (52) is arranged between the second connecting ring (50) and the clamping screw (37) and / or between the second connecting ring (50) and the shoulder (55).

13. Fuel valve according to one of claims 1 to 12, characterized in that the interior (32) is filled with a lubricant.

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