Injection system having at least one valve for metering a fluid

Abstract

The present invention relates to an injection system having at least one valve (2) for metering a fluid, in particular a fuel injection valve for injecting a gaseous fuel into a combustion chamber (3) of an internal combustion engine. The valve (2) comprises a connection piece (9) which forms the inflow-side inlet for the fluid. Furthermore, a first retaining element (7) and a second retaining element (8) are provided, wherein the first retaining element (7) has a through-opening (15) and the second retaining element (8) has a slotted opening (20), and wherein the through-opening (15) and the opening (20) are configured such that, together with at least one ball portion (22) of the connection piece (9), spherical mounting of the connection piece (9) in the retaining elements (7, 8) is ensured. According to the invention, the connection piece (9) passes all the way through the through-opening (15) in the first retaining element (7) and the opening (20) in the second retaining element (8) in an axial direction, in order for it to be possible to connect a supply line.

Description

[0001] Description

[0002] title

[0003] Injection or blowing system with at least one valve for metering a fluid

[0004] State of the art

[0005] The present invention relates to an injection or injection system with at least one valve for metering a fluid, in particular a fuel injection valve for injecting a gaseous fuel into a combustion chamber of an internal combustion engine. Specifically, the invention relates to an injection system with which hydrogen can be injected directly into the combustion chamber of a mixture-compressing, spark-ignition internal combustion engine.

[0006] A holder for a fuel injection system is known from DE 10 2014 200 597 A1. This holder serves to hold a fuel injector at a connection point of a fuel-carrying component. A connecting piece of the fuel injector has a partially spherical sealing surface that bears against a conical sealing surface of the component. The connecting piece is subjected to a preload force against the conical sealing surface. The preload force is applied by a clamping screw and transmitted via guide parts.

[0007] Furthermore, DE 10 2015 205 980 A1 discloses a hydraulic connection via which a fuel injector can be connected to a fuel-carrying component. This arrangement has a retaining bridge, which in turn has a support surface. A connecting piece of a fuel injector is provided, which can be supported on the support surface of the retaining bridge. Furthermore, a connecting body is provided, wherein a hydraulic connection is formed between the connecting piece of the fuel injector and the connecting body. For this purpose, a spherically convexly curved support surface is provided on the connecting body, and a conically extending support surface is formed on the connecting piece of the fuel injector. To form the hydraulic connection, contact is established between the connecting piece of the fuel injector and the connecting body at the convexly curved support surface and the support surface.The support surface of the connecting piece is axially symmetrical with respect to a longitudinal axis. In this respect, the mating area is a familiar metallic ball / cone seal.

[0008] Fuel injectors are known in various designs according to the state of the art. In high-pressure injection systems for liquid fuels, as the aforementioned prior art documents demonstrate, a metal-to-metal connection is increasingly being implemented between a fuel rail and an injector in the connection area. However, these metal-to-metal connections require relatively high forces, with which the sealing components must be pressed together with their surfaces to ensure sufficient sealing.

[0009] In the course of the search for alternative fuels to reduce or avoid harmful emissions, the aim is in particular to provide an optimized solution for connecting or suspending a fuel injection valve for directly injecting a gaseous fuel, in particular hydrogen, into a combustion chamber of an internal combustion engine.

[0010] Tests on engine test benches have shown that a simple transfer of the known connections or suspensions of direct-injection fuel injectors for liquid fuels to a connection or suspension of direct-injection fuel injectors for gaseous fuels is not possible. The higher the transverse force introduced by the hold-down device, the more the service life of the fuel injector, during which full functionality is guaranteed, is reduced due to the high stress. The present invention seeks to eliminate this disadvantage for a "suspended" fuel injector.

[0011] Disclosure of the invention

[0012] The injection or blow-in system according to the invention with at least one valve for metering a fluid, having the features of claim 1, has the advantage that optimal mounting of the valve is achieved and, in addition, an optimized connection of the thus mounted valve to a supply line is enabled. In the upper suspension area of ​​the valve, the design as a spherical bearing between a connection piece of the valve and two holding elements enables a metal-to-metal seal that prevents leaks even at high pressures. Furthermore, any angular misalignment that may exist between the supply line and the valve can also be compensated for with the system according to the invention. According to the invention, the connection piece is shaped such that it completely extends in the axial direction through a through opening in the first holding element and an ideally slotted opening in the second holding element.In addition, the design of the system according to the invention allows for simple and safe installation.

[0013] The subclaims describe preferred developments of the invention.

[0014] The metal-to-metal seal or bearing is preferably a metallic ball / cone seal, wherein the ball section is preferably provided on the connecting piece and the conical surfaces are provided on the holding elements.

[0015] Particularly preferably, the spherical section of the connecting piece is a spherically convex section whose radius is either constant or whose radii vary across the entire spherical section. For example, the spherical radii above and below an imaginary spherical equator can differ from each other. For consecutive spherical sections with different radii across the spherical section, the centers or pivot points of the spherical sections should ideally lie on the central axis of the connecting piece.

[0016] While the first retaining element, the second retaining element, and the connecting piece with the integrated spherical bearing form an upper suspension area for the valve, a second bearing point for the valve is formed at a lower valve end facing the combustion chamber in the area of ​​a sealing ring, which is preferably a PTFE sealing ring. The two bearing points are separated by a maximum distance in the axial direction. The valve is mounted via the sealing ring on the wall of the longitudinal bore of the cylinder head.

[0017] To prevent a large volume of damage in the longitudinal bore, an annular gap is advantageously formed between the wall of the longitudinal bore and the blow-off-side valve end. The radial dimension of the gap is only approximately 50 to 100 pm. Therefore, the outer diameter of the valve end and the inner diameter of the longitudinal bore in the cylinder head differ only very slightly.

[0018] The valve is aligned via the bearing point on the sealing ring at the valve end relative to the wall of the longitudinal bore. The ball joint in the upper suspension area provides the necessary degree of freedom. The valve must not be pressed axially onto the cylinder head; rather, it must "hang" freely, which can be described as a "suspended design" so that the bearing is provided exclusively by the lower sealing ring and the upper ball joint. Once the first retaining element is firmly connected to the cylinder head or a corresponding attachment body by means of a screw, the screws connecting the two retaining elements can be tightened alternately. This finally connects the valve firmly and securely to the hold-down device of the retaining element, largely free of lateral forces.

[0019] The present invention is preferably used in injection systems that inject hydrogen directly into a combustion chamber. In particular, the system is suitable for directly injecting hydrogen into the combustion chamber of an internal combustion engine.

[0020] drawing

[0021] Preferred embodiments of the invention will now be described in detail with reference to the accompanying drawings. Figure 1 is a schematic sectional view of an injection system in the upper suspension area according to an embodiment of the present invention.

[0022] Figure 2 is a schematic sectional and perspective view of the injection system in the upper suspension area according to Figure 1,

[0023] Figure 3 is a schematic sectional view of an injection system with two bearing points of the injector in the upper suspension area and a lower bearing area in the cylinder head,

[0024] Figure 4 shows the first holding element of the upper suspension area in a sectional view along the line IV-IV in Figure 5 as a single component,

[0025] Figure 5 shows the first holding element of the upper suspension area in a plan view as a single component,

[0026] Figure 6 shows the second holding element of the upper suspension area in a plan view as a single component,

[0027] Figure 7 shows the second holding element of the upper suspension area in a sectional view along the line VII-VII in Figure 6 as a single component and

[0028] Figure 8 shows the connecting piece of the fuel injection valve for the upper suspension area in a sectional view as a single component.

[0029] Preferred embodiments of the invention An injection system 1 according to a preferred embodiment of the invention is described in detail below with reference to Figures 1 to 8. This is preferably an injection system 1 for injecting a gaseous fuel, in particular hydrogen, into a combustion chamber 3 of an internal combustion engine (Figure 3). In principle, the system designed according to the invention can alternatively be used as an injection system 1 for injecting a liquid fuel into a combustion chamber 3 of an internal combustion engine, whereby from now on only reference will be made to an injection system 1. Alternative embodiments not shown in the figures are also mentioned below.

[0030] The injection system 1 comprises at least one valve 2 for metering a fluid, in particular a gaseous fuel such as hydrogen, but also CNG, methane, ammonia, etc. The valve 2 is designed as an injection valve 2 that injects directly into the combustion chamber 3. The gas to be injected flows through the valve 2. The gas enters the valve 2, which can also be referred to as an injector, via an inflow-side valve end 5, while the metering, jet shaping, and processing of the gaseous medium takes place at a downstream valve end 6 facing the combustion chamber 3 (Figure 3).

[0031] The injection system 1 has two bearing points for the valve 2, with Figures 1 and 2 each showing the upper suspension area of ​​the valve 2. Figure 1 shows a schematic sectional view of the injection system 1 in the upper suspension area, while Figure 2 shows a schematic sectional and perspective view of the injection system 1 in the upper suspension area according to Figure 1.

[0032] As can be seen from Figure 1, the injection system 1 further comprises a first holding element 7 and a second holding element 8, which together with a connecting piece 9 form the upper bearing point in the suspension area of ​​the valve 2. The first holding element 7 is, for example, L-shaped in section, wherein the holding element 7 is characterized above all in that a through-bore 12 is provided in a flange area 11, through which a connecting means, such as a screw 13, can be guided, with which the valve 2 can be clamped to an attachment part, in this case a cylinder head 10 (Figure 3). In addition to the longitudinally extending flange area 11, the first holding element 7 has a holding area 14 which runs largely at a right angle to it and which has a through-opening 15 through which the connecting piece 9 projects.The through-opening 15 is formed in a partial area in such a way that an inner conical conical surface 16 is present.

[0033] The second lower holding element 8 is disc-shaped and slotted. The connecting piece 9 also passes through the second holding element 8, and its slot allows it to be pushed sideways onto the connecting piece 9. The second holding element 8 has, for example, three threaded holes 18, each evenly distributed over 120°, into which screws 19 can be screwed. The screws can be guided through corresponding through-holes 17 in the first holding element 7. In this way, the two first and second holding elements 7, 8 can be clamped together using the screws 19. Ideally, the three fastening points with the screws 19 represent the best statically determined solution; however, more or fewer fastening points are also conceivable.A slotted opening 20 of the second retaining element 8, like the through-opening 15 of the first retaining element 7, is shaped in a partial region such that an inner conical conical surface 21 is present, with the two conicities running in opposite directions, expanding conically in the first retaining element 7 and tapering conically in the second retaining element 8, as seen in the direction of flow. Both conical surfaces 16 and 21, together with a spherically shaped portion of the connecting piece 9 having a spherical section 22, form the upper bearing point.

[0034] A spherical bearing is understood to be a bearing that is either a ball / cone bearing or is designed similarly to a rod end or a ball joint with two spherically curved corresponding bearing surfaces.

[0035] As an alternative to the described embodiment of the second lower holding element 8 with a slotted opening 20, the holding element 8 can also be provided with an opening 20 without a slot, so that the holding element 8 can be plugged onto the connecting piece 9.

[0036] In the illustrated embodiment, the connecting piece 9 is designed as a separate tubular individual component. The connecting piece 9 has an inner longitudinal opening 25 through which flow can take place. In addition to the central spherical section 22, the connecting piece 9 also has an inlet-side connecting section 26 and an outlet-side connecting section 27. The inlet-side connecting section 26 is designed, for example, in such a way that a line connection is present, i.e. that a supply line (not shown), which in turn branches off from a distribution line or a rail to the valve 2, for example, can be plugged or pushed onto it and is secured, for example, by means of a union nut on the connecting section 26. Accordingly, the connecting section 26 is provided on the inlet side with chamfers or an overlap area with an enlarged diameter.

[0037] The outlet-side connecting section 27 is designed, for example, to enable a connection to the valve 2. For this purpose, the connecting section 27 has an internal thread 28 at the end of its longitudinal opening 25, with which the connecting piece 9 can be screwed onto the inlet-side end of the valve 2. A sleeve body 29 can optionally be inserted inside the connecting piece 9. This sleeve body 29 is supported on a conical valve inlet 30 and serves to improve the centering and sealing of the connecting piece 9 on the valve 2 and can be pressed into a type of sliding fit on the valve inlet 30. In addition to the screw connection shown, other joining methods for securing the connecting piece 9, such as welding, are also conceivable.

[0038] It should be explicitly emphasized that the connecting piece 9 can alternatively also be a direct part of the valve 2, which then has an adequate shape as part of the valve housing, but without a connecting section 27 being necessary, as Figure 3 shows schematically.

[0039] According to the invention, the connecting piece 9, with its axial extension, completely penetrates the through-opening 15 of the first holding element and the opening 20 of the second holding element 8 in the axial direction, also in order to be able to realize the line connection for the supply line (not shown).

[0040] The upper suspension area of ​​the valve 2 is characterized by a bearing with a metallic bearing, which is implemented as a ball / cone connection between the spherical section 22 of the connecting piece 9 and the two conical surfaces 16 and 21 of the first and second holding elements 7 and 8. The spherical section 22 should expressly be understood in general as a spherically convex section, the radius of which does not necessarily have to be constant over the entire spherical section 22. Rather, it is even conceivable that different radii are provided for the individual spherical areas above and below an imaginary spherical equator, so that these spherical areas can interact with the conical surfaces 16 and 21, ideally matched to the inclination or conicity of the conical surfaces 16 and 21, for optimized, lateral force-reduced bearing. For example,The spherical area of ​​the spherical section 22 toward the upper conical surface 16 should have a smaller radius than the radius of the spherical area of ​​the spherical section 22 toward the lower conical surface 21. The centers (pivot points) of the spherical areas should ideally lie on the central axis of the connecting piece 9.

[0041] The upper end of the valve 2 can be provided with a plastic overmold 31 which protects an electrical connection 32 for an actuator of the valve 2, not shown.

[0042] Figure 3 shows a schematic sectional view of an injection system 1 with two bearing points for the valve 2 in the upper suspension area, which was described in detail with reference to Figures 1 and 2, and a lower bearing area in the cylinder head 10. The valve 2 has, on its valve end 6 facing the combustion chamber 3, a circumferential sealing ring 33 on the outer circumference, which represents the second bearing point for the valve 2. Ideally, this is a PTFE sealing ring that is dimensioned or inserted into an annular groove on the valve 2 in such a way that a spherical bearing is also produced, since the sealing ring 33 bulges slightly radially outwards when the valve 2 is installed, so that under compression pressure there is only an approximately linear bearing of the sealing ring 33 on the wall of a longitudinal bore 35 in the cylinder head 10 for receiving the valve 2.Advantageously, the diameter of the valve 2 at its valve end 6 and the diameter of the longitudinal bore 35 differ only slightly. Thus, for optimal support, the annular gap formed between the wall of the longitudinal bore 35 and the valve end 6 can be only approximately 50 to 100 pm in its radial extent. Particularly advantageously, the damage volume is kept very small in the longitudinal bore 35 of the cylinder head 10 close to the combustion chamber 3. With the above-described fastening of the valve 2, the two bearing points are located as far apart from each other as possible. Depending on the construction, the valve 2 can even have a certain "arch shape" without this introducing a transverse force into the valve 2 due to the described hold-down.

[0043] Assembly is carried out by inserting the valve 2 together with the connecting piece 9 from the downstream side through the through-opening 15 in the first upper holding element 7. The spherical section 22 of the connecting piece 9 or on the valve 2 touches the conical surface 16 in the first holding element 7. A line contact is established between the two components. In the next step, the second lower holding element 8 is inserted over the connecting piece 9 or the valve 2 in a sideways movement and fastened to the first holding element 7 using the three screws 19. The screws 19 should initially only be tightened very lightly. Screwing the parts together creates a ball joint which enables the valve 2 to be held in a defined position even when tilted.Following the assembly of this hold-down unit, the device consisting of valve 2 and the two holding elements 7 and 8 can be installed in the cylinder head 10 of the internal combustion engine, but also on a spray test bench, etc. or another type of attachment.

[0044] The valve 2 now aligns itself via the bearing point on the sealing ring 33 at the valve end 6 of the valve 2 relative to the wall of the longitudinal bore 35. The ball joint in the upper suspension area provides the necessary degree of freedom. The valve 2 must not be pressed axially onto the cylinder head 10; rather, it must "hang" freely, which can be described as a "suspended design" so that the bearing is achieved exclusively by the lower sealing ring 33 and the upper ball joint. Once the first holding element 7 is firmly connected to the cylinder head 10 or a corresponding body by means of the screw 13, the screws 19 connecting the two holding elements 7 and 8 can be alternately tightened. This finally firmly and securely connects the valve 2 to the hold-down device of the holding element 7.

[0045] Figure 4 shows the first holding element 7 of the upper suspension region in a sectional view along the line IV-IV in Figure 5 as an individual component, while Figure 5 shows the first holding element 7 of the upper suspension region in a plan view as an individual component. The two figures illustrate the specific inventive design of the first holding element 7. The L-shaped contour of the first holding element 7 in cross-section is clearly visible, with the two legs of the holding element 7 running largely at right angles to one another and forming, on the one hand, the flange region 11 with at least one through-bore 12 for a screw 13 and, on the other hand, the holding region 1. The holding region 14 has the through-opening 15 required for the ball joint or the cardanic bearing, which opening can be penetrated by the connecting piece 9 of the valve 2.The through-opening 15 is shaped in a partial area such that the inner conical surface 16 is present. The angle a enclosed by the conical surface 16 can be individually adjusted depending on the size of the radius of the interacting spherical section 22 of the connecting piece 9. The angle a will be in the range of 30° to 60°, in particular between 40° and 55°, preferably between 45° and 50°. However, angles a greater than 90° and even up to approximately 150° are also conceivable.

[0046] Viewed from above in a plan view, the contour of the

[0047] Holding element 7 of a boat, wherein the holding area 14 can taper to a point on its "bow side" to save material, without the strength of the holding area 1 of the holding element 7 being impaired. In the holding area 1 of the holding element 7, for example, three through-holes 17 are provided, which serve to pass through three screws 19 in order to enable the two holding elements 7 and 8 to be clamped together with corresponding threaded holes 18 in the second holding element 8. The three through-holes 17 are, for example, arranged largely evenly distributed over 120° in the holding area 1 around the through-hole 15. Ideally, the three fastening points with the screws 19 represent the best statically determined solution; however, more or fewer fastening points are also conceivable.

[0048] Figure 6 shows the second retaining element 8 of the upper suspension area in a plan view as a single component, while Figure 7 shows the second retaining element 8 of the upper suspension area in a sectional view along the line VI I-VI I in Figure 6 as a single component. The basic contour of the retaining element 8 is modeled on the retaining area 1 of the retaining element 7, since these two parts are connected to one another in a largely congruent manner via the screws 19.

[0049] In addition to the threaded holes 18, the second holding element 8 is characterized by the slotted opening 20, which, like the through-opening 15 of the first holding element 7, is shaped in a partial area such that an inner conical conical surface 21 is present. The conical design of the conical surface 21 can extend over the entire thickness of the holding element 8, at least in the closed end area of ​​the opening 20, as shown in particular in Figure 7. The inner conical conical surface 21 extends over at least 180° in the closed end area of ​​the opening 20. Alternatively, only individual arc segments, each with a corresponding conical surface 21, can be provided. The angle ß enclosed inside by the conical surface 21 can be individually adjusted depending on the size of the radius of the spherical section 22 of the connecting piece 9 that interacts with it.The angle ß will be in the order of 30° to 60°, in particular between 40° and 55°, preferably between 45° and 50°.

[0050] Towards the open end region of the opening 20, this has, for example, one or more chamfers 36 which run from the conical surface 21 to the open end, do not necessarily extend over the entire thickness of the holding element 8 and have a different angle of inclination than the angle ß of the conical surface 21 and serve to improve and simplify the insertion and attachment of the second holding element 8.

[0051] Both conical surfaces 16 and 21, together with the spherically shaped portion of the connecting piece 9, which includes the spherical section 22, form the upper spherical bearing point. The alignment of the conical surfaces 16 and 21 to the spherical section 22 should be such that, ideally, line contact occurs largely in the contact area of ​​the bearing point, with the line contact occurring approximately centrally on the respective conical surfaces 16 and 21.

[0052] Figure 8 shows a sectional view of the connecting piece 9 of the fuel injection valve 2 for the upper suspension area as a single component. As already explained, the connecting piece 9 is designed as a tubular single component. The inner longitudinal opening 25 serves as a flow path for the fuel, in particular a gaseous fuel, into the valve 2. The inlet-side connecting section 26 has an external thread 37 or several sections of external threads 37 on its outer circumference. The inlet-side connecting section 26 is designed such that a line connection is provided for a supply line (not shown), which can be plugged, pushed on, or screwed on. The supply line can be secured, for example, by means of a union nut on the connecting section 26. Accordingly, the connecting section 26 is provided with chamfers on the inlet side to create an optimized connection.

Claims

Claims 1. Injection or blow-in system with at least one valve (2) for metering a fluid, in particular a fuel injection valve for injecting a gaseous fuel into a combustion chamber (3) of an internal combustion engine, wherein the valve (2) comprises a connecting piece (9) which forms the inlet for the fluid on the inlet side, and with a first holding element (7) and a second holding element (8), wherein the first holding element (7) has a through-opening (15) and the second holding element (8) has an opening (20), wherein the through-opening (15) and the opening (20) are designed such that, together with at least one spherical section (22) of the connecting piece (9), a spherical mounting of the connecting piece (9) in the holding elements (7, 8) is ensured, characterized in that the connecting piece (9) completely covers the through-opening (15) of the first holding element (7) and the opening (20) of the second holding element (8) in the axial direction protrudes.

2. System according to claim 1, characterized in that the connecting piece (9) is a single component firmly connected to the valve (2) or a part directly emerging from the valve housing of the valve (2).

3. System according to claim 1 or 2, characterized in that the connecting piece (9) is a tubular component having an inner longitudinal opening (25) as a flow path for the fluid.

4. System according to one of the preceding claims, characterized in that the through-opening (15) of the first holding element (7) is shaped in a partial area such that an inner conical conical surface (16) is present and the opening (20) of the second holding element (8) is shaped in a partial area such that an inner conical conical surface (21) is present, wherein the two conicities run in opposite directions, widening conically in the first holding element (7) and tapering conically in the second holding element (8) as seen in the direction of flow.

5. System according to claim 4, characterized in that the spherical portion (22) of the connecting piece (9) ensures a spherical mounting of the connecting piece (9) by interacting with the conical surfaces (16, 17) in the holding elements (7, 8).

6. Installation according to claim 4 or 5, characterized in that the angle (α, β) enclosed in each case by the inside of the conical surface (16, 17) is in the order of magnitude of 30° to 60°, in particular between 40° and 55°, preferably between 45° and 50°.

7. System according to one of the preceding claims, characterized in that the spherical section (22) of the connecting piece (9) is a spherically convexly curved section, the radius of which is either constant or the radii of which vary over the entire spherical section (22).

8. System according to claim 7, characterized in that in the case of successive spherical regions with different radii over the spherical section (22), the centers or pivot points of the spherical regions lie on the central axis of the connecting piece (9).

9. System according to one of the preceding claims, characterized in that the opening (20) of the second holding element (8) is slotted.

10. System according to one of the preceding claims, characterized in that the first holding element (7) and the second holding element (8) can be clamped against one another, in particular by means of screws (19), preferably three screws (19), which are arranged evenly distributed around the circumference. 11 . System according to one of the preceding claims, characterized in that the first holding element (7), the second holding element (8) and the connecting piece (9) with the spherical bearing integrated therein form an upper suspension region for the valve (2), while a second bearing point of the valve (2) is formed at a lower valve end (6) in the region of a sealing ring (33), in particular a sealing ring (33) made of PTFE.

12. System according to claim 11, characterized in that the valve (2) can be introduced into a longitudinal bore (35) of a cylinder head (10), wherein the bearing of the sealing ring (33) takes place on the wall of the longitudinal bore (35) and wherein the annular gap formed between the wall of the longitudinal bore (35) and the valve end (6) is only approximately 50 to 100 pm in its radial extent.

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