Fuel valve for dispensing fuel in metered manner

Abstract

The invention relates to a fuel valve for dispensing fuel in a metered manner, comprising a housing (1) which can be filled with fluid fuel and which has an outlet opening (7). According to the invention, a valve needle (15) is arranged in the housing (1), which valve needle can be moved in the longitudinal direction thereof and interacts with a valve seat (17) for opening and closing the outlet opening (7), the valve needle (15) being surrounded over a part of the length thereof by a bellows (30) which seals the interior (32). The bellows (30) is connected in a fluid-tight manner on the end facing the outlet opening (7) with an attachment 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).

Description

Technical Field

[0001] The invention relates to a fuel valve which is used for metering fuel, in particular gaseous fuel. Background Art

[0002] For example, valves for metering gaseous or liquid fuels are used to meter fuel into a combustion chamber or intake duct of an internal combustion engine. It is important to introduce the correct amount of fuel 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 20 21 200 689 A1 and has a piston-shaped valve element, which is moved by an electromagnet and thereby opens and closes a metering opening. In this case, the gaseous fuel flows through the valve element and thus reaches the metering opening. The valve element itself is guided in one or more sections within the housing, wherein, for normal operation, a lubricant is present, which wets the guide surface of the valve element, thereby ensuring the mobility of the valve element.

[0003] In order to prevent the lubricant from mixing with the fuel, the valve element is located in the lubricant area, which is sealed by a bellows, which prevents the fuel from mixing with the lubricant, but still allows a longitudinal movement of the valve element. The bellows is connected to the valve element at both ends by a fluid-tight welded connection, thereby sealing the lubricant chamber from the fuel.

[0004] The production of these welded connections is complex and requires special equipment for serial production. In addition, the assembly of the valve element is difficult because it usually consists of multiple parts and the bellows must not be subjected to torque loads. As a result, the production of valve elements with welded bellows is complex and expensive. Summary of the invention

[0005] The fuel valve according to the invention has the following advantages: the sealing of the lubricant chamber or the inner space surrounding the valve element relative to the outer space, in which the fuel to be metered is guided, can be realized simply and flexibly. To this end, the fuel valve for outputting fuel in a metered manner has a housing, which can be filled with a fluid fuel and has an outlet opening. A valve needle is arranged in the housing, which can move in its longitudinal direction and cooperate with a valve seat for opening and closing the outlet opening, wherein the valve needle is surrounded by a bellows over a part of its length, which seals the inner space. The bellows is connected to an attachment ring in a fluid-tight manner at the end facing the outlet opening, and the attachment ring is clamped against a sealing seat on the nozzle needle by a clamping nut surrounding the valve needle.

[0006] The attachment ring is connected to the bellows in a fluid-tight manner via a welded connection, so that no fluid can escape from the interior of the bellows to the outside at this location. By clamping the attachment ring against the sealing seat on the valve needle, a fluid-tight sealing of the interior space is ultimately achieved. The fixing by means of the attachment ring also allows the valve needle to be disassembled again and the bellows to be replaced if necessary, thereby achieving greater flexibility in the design of such a fuel valve and in terms of maintenance and repair. In the context of the present patent application, a fluid is understood to be a gas or a liquid.

[0007] In a first advantageous configuration, the clamping nut engages in a thread formed on the outside of the valve needle. Such a thread is easy to manufacture and can be attached to different locations of the valve needle depending on the installation conditions.

[0008] In another advantageous configuration, a clamping sleeve is arranged between the attachment ring and the clamping nut, which also surrounds the valve needle and transmits the extrusion force of the clamping nut to the attachment ring. As a result, the clamping nut can be arranged at a significant distance from the sealing surface, which can achieve additional freedom in design modifications.

[0009] In a further advantageous embodiment, the valve needle forms an outer contour in the region of the clamping sleeve, into which the clamping sleeve engages in a form-fitting manner, thereby preventing the clamping sleeve from rotating on the valve needle. The torque of the clamping nut is therefore not transmitted to the attachment ring, and no further measures have to be taken to prevent a rotation of the attachment ring and thus a possible twisting of the bellows.

[0010] In another advantageous configuration, the sealing seat is conically designed. This enables good sealing and ensures self-centering of the attachment ring on the valve needle. Here, in an advantageous manner, the contact surface on the attachment ring, with which the clamping nut rests on the sealing seat, is also conically designed.

[0011] In another advantageous configuration, the sealing seat is designed as a flat annular surface, and a corresponding flat contact surface is configured on the attachment ring, which also forms an annular surface and with which the attachment ring rests on the sealing seat. Such an annular surface can be manufactured cost-effectively and can withstand high extrusion forces.

[0012] In a further advantageous embodiment, a sealing ring is arranged between the attachment ring and the nozzle needle. The sealing ring ensures an additional seal and thus increases the operational reliability. It can also be provided that the sealing ring fulfills the main sealing function and that only a partial seal exists between the attachment ring and the sealing seat. In this case, the shape of the sealing seat can have any shape, i.e. can be embodied as a flat seat or a conical seat with any opening angle.

[0013] In a further advantageous embodiment, the end of the bellows facing away from the outlet opening is connected in a sealing manner to a second attachment ring. Here, the second attachment ring advantageously rests on a shoulder in the housing facing the outlet opening. Thus, a seal is established between the valve needle and the housing, so that the interior space, which contains lubricant or other fuel, is reliably sealed off from the fuel.

[0014] In a further advantageous embodiment, the interior space is filled with a lubricant which can wet the valve needle in the housing and guide it in different regions in order to ensure a low-friction movement and thus a long service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The accompanying drawings show different embodiments of the fuel valve according to the invention.

[0016] Figure 1 shows a longitudinal section through a fuel valve according to the invention, wherein only the essential components are shown,

[0017] Figure 2 Show Figure 1 An enlarged view of the local area marked with II,

[0018] Figure 3 Shown in Figure 2 Another embodiment in the same diagram,

[0019] Figure 4 Another embodiment of a bellows seal is shown.

[0020] Figure 5 A further embodiment of a bellows seal is shown.

[0021] Figure 5A The valve needle according to the present invention is shown in Figure 5 A cross section in the region of the cross-sectional plane marked with A,

[0022] Figure 6 Shown with Figure 2 Another embodiment of the same diagram, and

[0023] Figure 7 Such another embodiment is shown. DETAILED DESCRIPTION

[0024] Figure 1The fuel valve according to the invention is shown in longitudinal section, wherein only the essential components are shown. The fuel valve has a housing 1, which comprises a valve body 2 and a sleeve 3, which are connected to each other in a fluid-tight manner by a clamping device not shown in detail in the drawing. A thread 6 is formed inside the valve body 2, into which a nozzle body 4 is screwed, which protrudes from the valve body at the outlet-side end of the valve body 2. This 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 being screwed onto the thread 6. The valve tube 5 serves to shape and guide the discharged fuel, which flows out of an outlet opening 7 in the nozzle body 4 into the valve tube 5, wherein preferably gaseous fuel is metered.

[0025] A pressure chamber 8 is formed in the housing 1, which can be filled with liquid fuel or gaseous fuel to be metered at 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 a nozzle space 14 formed in the nozzle body 4, wherein the connection is established via an oblique bore 9 in the valve body 2 and a further oblique bore 13 in the nozzle body 4. The fuel in the pressure chamber 8 flows to the outlet opening 7 formed at the outlet-side end of the nozzle body 4.

[0026] The piston-shaped valve needle 15 is arranged longitudinally displaceably inside the nozzle body 4. The valve needle 15 has a valve disk 16 at its end facing the outlet side of the housing 1, which cooperates with a valve seat 17 surrounding the outlet opening 7 to open and close the outlet opening 7. Figure 1 If the valve needle 15 moves downward in the middle, the annular gap between the valve disk 16 and the valve seat 17 is controlled to open (aufgesteuert), and the fuel can flow out of the nozzle chamber 14, wherein the fuel is guided through the valve tube 5. If the valve needle 15 moves against the valve seat 17, the outlet opening 7 is closed again.

[0027] The nozzle needle 15 extends over the entire length of the nozzle body 4 and is guided in the 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 a connecting hole 33, so that when the fuel valve is in operation, the annular space is filled with the fuel to be metered. Alternatively, it can also be provided that the fuel flows directly through the bellows 30, for example, in that the oblique hole 9 leads directly into the annular space 31 and the intermediate space 10 between the nozzle body 4 and the valve body 2 is omitted.

[0028] The valve needle 15 is surrounded by a bellows 30 which is arranged in the interior of the nozzle body 4 and is connected in a fluid-tight manner with its end facing the outlet opening 7 via a first welded connection 35 to an attachment ring 40 which is formed integrally with a clamping sleeve 21 surrounding the valve needle 15. The attachment ring 40 is supported with its outlet opening-side end on a sealing seat 41 of the valve needle 15, while the opposite end of the clamping sleeve 21 bears against the spring sleeve 22. A thread 19 is formed on the end of the valve needle 15, into which a clamping nut 23 engages, which clamps the spring sleeve 22 against the clamping sleeve 21 and thus the attachment ring 40 against the sealing seat 41.

[0029] The bellows 30 is connected at its end opposite the first welded connection 35 via a second welded connection 36 to a second attachment ring 50 in a fluid-tight manner, which is clamped against a shoulder 39 in the nozzle body 4 via a support element 26. In this case, for adjustment to the correct distance, a first adjustment shim 28 is arranged between the second attachment ring 50 and the shoulder 39 formed in the nozzle body 4, and a second adjustment shim 29 is arranged between the support element 26 and the second attachment ring 50. The support element 26 is clamped by a clamping screw 37, which engages in a thread inside the nozzle body 4. A valve spring 25 is arranged between the support element 26 and the spring sleeve 22 under pressure preload, by which the valve needle 15 is pressed against the valve seat 17. If a sufficiently large longitudinal force is applied to the valve needle 15 by an electric actuator (not shown in this figure), for example an electromagnet, the valve needle moves in the longitudinal direction against the force of the valve spring 25 in order to open the outlet opening 7.

[0030] The bellows 30 surrounds an inner space 32 which can be filled with lubricant. The lubricant wets the guide section 24 between the spring sleeve 22 and the support element 26 so that the valve needle 15 can move largely frictionlessly. An intermediate space is left between the second attachment ring 50 and the clamping sleeve 21 through which the lubricant can flow. In the region of the support element 26, the lubricant flow via the through hole 27 is ensured. Here, the bellows 30 is flexible in the longitudinal direction so that the movement of the valve needle 15 in the housing 1 is not hindered, but the inner space 32 is sealed relative to the annular space 31, and thus the lubricant is sealed relative to the fuel.

[0031] Figure 2 According to another embodiment of the present invention, Figure 1The portion marked with II, in which only half of the fuel valve is shown along the central axis 11. The bellows 30 is connected to a separate attachment ring 40 with its end facing the outlet opening 7. The attachment ring 40 surrounds the valve needle 15 and is placed on the valve needle 15 with a conical abutment surface 44 on a sealing seat 41 that is also conical. A fluid-tight welded connection is constructed between the bellows 30 and the attachment ring 40. The clamping nut 23 is arranged in the bellows 30 and surrounds the valve needle 15. Here, the clamping nut 23 clamps the attachment ring 40 against the sealing seat 41, wherein it engages in the thread 19 on the valve needle 15, which is also arranged in the bellows 30. Since the clamping nut 23 is directly against the attachment ring 40 here, the clamping sleeve 21 is omitted in this embodiment. The valve spring 25, which is not shown here, also loads the valve needle 15 in a different design, thereby also eliminating the spring sleeve 22. A fluid-tight connection is also achieved by the attachment ring 40 resting on the sealing seat 41, so that the interior space 32 bounded by the bellows 30 is sealed and the lubricant located therein cannot mix with the fuel in the annular space 31. Since the valve needle 15 does not rotate when the clamping nut 23 is tightened and the bellows 30 could therefore be damaged, retaining contours 45, 46 can be provided on the end of the valve needle 15 in order to retain the valve needle 15 during the screwing process. The retaining contours 45, 46 can be formed, for example, with a wrench face. The form of construction.

[0032] Figure 3 With Figure 2 The same figure shows another embodiment of the invention. The attachment ring 40 is not preloaded directly against the sealing seat 41 by the clamping nut 23, but as in Figure 1 In the embodiment of the present invention, the clamping sleeve 21 is preloaded. The clamping sleeve 21 surrounds the valve needle 15 and transmits the force of the clamping nut 23 to the attachment ring 40. As a result, the clamping nut 23 can also be positioned further away from the attachment ring 40, which improves the accessibility of the clamping nut 23 and facilitates installation. The clamping nut 23 can also be arranged outside the bellows 30.

[0033] Figure 4 A further embodiment of the arrangement according to the invention of an attachment ring 40' is shown. The attachment ring 40' here has a flat abutment surface 44', which rests on a likewise flat sealing seat 41'. This construction of the attachment ring 41' and the abutment surface 44' is easy to manufacture and allows a horizontal displacement of the attachment ring 40'. In order to achieve a reliable seal, a ring sealing ring 48 is additionally provided between the attachment 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 a support for the first attachment ring 40'. As a result, more degrees of freedom are obtained in the configuration of the sealing seat 41' or the abutment surface 44'.

[0034] exist Figure 5 In Figure 3 The same illustration shows another embodiment. Here too, the bellows 30 is connected with its end facing the outlet opening 7 via a welded connection 35 to an attachment ring 40 in a fluid-tight manner. In order to seal the opposite end of the bellows 30, a second attachment ring 50 is also present here. The second attachment ring 50 is also connected to the bellows 30 via a welded connection 36 and rests on a shoulder 55 in the nozzle body 4. In addition, a sealing ring 47 is arranged between the second attachment ring 50 and the nozzle body 4, in order to seal the bellows 30 in a fluid-tight manner. Figure 4 , additional sealing of the interior space 32 is achieved as shown in the figure. The shoulder 55 is designed to be flat, so that the sealing ring 47 optimizes the sealing. The clamping force acting on the attachment ring 40 is also generated here by the clamping sleeve 21 and the clamping nut 23. In order 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. For this purpose, Figure 5A Shows Figure 5 , a cross section of the embodiment shown in FIG. 1 along line A. Since the clamping sleeve 21 and the valve needle 15 engage with each other, a twisting of the clamping sleeve 21 is prevented when the clamping nut 23 is screwed on, so that no torque is applied to the first attachment ring 40. In addition, retaining contours 45, 46 can also be formed on the valve needle 15 in order to fix the valve needle when the clamping nut 23 is screwed on. External and internal contours that engage with each other can also be provided between the attachment ring 40 and the valve needle 15 or between the spring sleeve 22 and the valve needle 15.

[0035] Figure 6 With Figure 5 The same figure shows another embodiment. The second attachment ring 50 is also preloaded against the shoulder 55 by the clamping screw 37, wherein two adjustment washers 52, 53 are used: the first adjustment washers 52 are arranged between the clamping screw 37 and the second attachment ring 50, and the second adjustment washers 53 are arranged between the second attachment ring 50 and the shoulder 55. As a result, the position of the second attachment ring 50 in the nozzle body 4 can be adjusted accurately, so that different degrees of preload of the bellows 30 do not reduce or increase the spring force of the valve spring 25. Here, the first adjustment washers 52 and the second adjustment washers 53 do not have to be constructed with the same thickness, as in Figure 7 Here, without changing the position of the clamping screw 37, the first adjusting shim 52 is constructed to be thicker than the second adjusting shim 53, wherein the total thickness of the two adjusting shims 52, 53 corresponds to Figure 6 By adjusting the configuration of the spacers 52, 53, the second attachment ring 50 is positioned further toward the direction of the first attachment ring 40 if necessary.

[0036] The movement of the valve needle 15 is preferably facilitated by Figure 1 The valve needle 15 can also be moved by means of another electric actuator, such as a piezoelectric actuator or a magnetostrictive actuator. Servo-hydraulic movement of the valve needle 15 is also possible.

Claims

1. A fuel valve for discharging fuel in a metered manner, the fuel valve comprising: a housing (1) which can be filled with a fluid fuel and has an outlet opening (7); and A valve needle (15) is arranged in the housing (1), the valve needle being movable in its longitudinal direction and cooperating with a valve seat (17) for opening and closing the outlet opening (7), wherein: The valve needle (15) is surrounded over a portion of its length by a bellows (30), which seals off an interior space (32). It is characterized in that the bellows (30) is fluid-tightly connected to an attachment ring (40) at the end facing the outlet opening (7), and the attachment ring is clamped against a sealing seat (41) on the valve needle (15) by a clamping nut (23) surrounding the valve needle (15).

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

3. The 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 attachment ring (40), and the clamping sleeve transmits the pressing force of the clamping nut (23) to the attachment ring (40).

4. The fuel valve according to claim 3, characterized in that The valve needle (15) forms an outer contour (49) in the region 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. The fuel valve according to any one of claims 1 to 4, characterized in that The sealing seat (41) is of conical design.

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

7. The fuel valve according to any 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 designed on the attachment ring (40)', which also forms an annular surface and with which the attachment ring (40)' rests on the sealing seat (41).

8. The fuel valve according to any one of claims 1 to 7, characterized in that A sealing ring (48) is arranged between the attachment ring (40) and the nozzle needle (15).

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

10. The fuel valve according to claim 9, characterized in that The second attachment ring (50) rests on a shoulder (55) in the housing (1) facing the outlet opening (7).

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

12. The fuel valve according to claim 11, characterized in that A first adjustment shim (51) is arranged between the second attachment ring (50) and the clamping screw (37) and / or a second adjustment shim (52) is arranged between the second attachment ring (50) and the shoulder (55).

13. The fuel valve according to any one of claims 1 to 12, characterized in that The inner space (32) is filled with lubricant.

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