Gas injector with improved operating behavior

Abstract

The present invention relates to a gas injector for injecting a gaseous medium, comprising a magnetic actuator (2) with an armature (20), an inner pole (21), and a coil (22); a closing element (3) which opens and closes a gas path (14) at a sealing seat (5), wherein the closing element (3) comprises a valve needle (30) and an armature bolt (31) firmly connected to the armature (20); a sealed lubricant chamber (4) filled with lubricant, in which the armature (20) and the armature bolt (31) are arranged; a return element (6) which returns the closing element (3) to a closed initial position; a sleeve (8) which only partially encloses the valve needle (30) and the armature bolt (31), wherein a joint is formed between the valve needle (30) and the armature bolt (31);wherein the joint lies in particular in a plane E perpendicular to a central axis XX of the gas injector and is surrounded by the sleeve (8), and wherein the sleeve (8) comprises a damping device (7) to dampen an impact between the valve needle (30) and the anchor bolt (31).

Description

State of the art

[0001] The present invention relates to a gas injector for injecting a gaseous medium, in particular hydrogen or natural gas or the like, with improved operating behavior, in particular with regard to impact on components.

[0002] Gas injectors are known in various designs from the prior art. Due to the non-lubricating properties of the injected gas compared to fuel injectors for liquid fuels, it has been proposed to provide a so-called lubricant chamber in which moving parts of the gas injector can be arranged and lubricated. This significantly extends the service life of the gas injector. A closing element of the gas injector can be designed in two parts with a valve needle and an armature bolt. When the gas injector opens, the armature bolt moves the valve needle, with the armature bolt and the valve needle abutting against one another at a joint. As soon as the armature, which is firmly connected to the armature bolt, reaches a stop, the valve needle moves on its own. This separates the components, creating a gap between the armature bolt and the valve needle.When the valve needle is reset, which occurs via a preload element such as a spring, the gap between the armature pin and the valve needle is closed again. This can result in sudden contact between the armature pin and the valve needle. This can lead to additional wear on the components and cause transverse forces, which promote wear at other parts of the gas injector. This wear can become even more pronounced as the gas injector's service life increases. Disclosure of the invention

[0003] The gas injector according to the invention for injecting a gaseous medium with the features of claim 1 has the advantage that improved protection of a valve needle and an armature bolt, which form a closing element, is possible. At a joint at which, when the gas injector is closed, the armature bolt and the valve needle abut one another at mutually facing contact surfaces, the armature bolt and the valve needle are located in a sealed lubricant chamber. The lubricant chamber is filled with a liquid, e.g., oil or the like. The joint between the valve needle and the armature bolt is preferably located in a plane E, which is in particular perpendicular to a central axis XX of the gas injector. Due to the arrangement of the joint between the valve needle and the armature bolt, the joint is fundamentally protected against corrosion and wear, with the oil present there, in particular, protecting against corrosion.However, during a closing process of the gas injector, wear can occur at the joint between the valve needle and the armature bolt due to impact loads. The extent of wear depends in particular on the needle mass, the restoring force for the valve needle, the temperature, or other external factors. If, during an opening process, the valve needle separates from the armature bolt, which, due to an armature stop, for example, is no longer moved together with the valve needle in the opening direction, and the valve needle and armature bolt separate, liquid lubricant flows into the gap between the contact surfaces of these components. According to the invention, this lubricant located in the gap can now be removed in a defined and controlled manner during a closing process of the gas injector, thereby dampening the contact between the valve needle and the armature bolt during the closing process.This can significantly reduce wear on the contact surfaces between the valve needle and the armature pin. This also has a positive impact on other potential wear points on the gas injector during operation. This can further improve the overall service life of the gas injector.

[0004] This is achieved according to the invention in that the gas injector comprises a magnetic actuator with an armature, an inner pole, and a coil. Furthermore, the gas injector comprises the two-part closing element, which comprises the valve needle and the armature bolt firmly connected to the armature. The closing element thereby releases and closes a sealing seat of a gas path. Furthermore, the enclosed lubricant chamber is provided, which contains a liquid lubricant, in particular oil or the like, and in which the armature and the armature bolt are arranged. Furthermore, a return element is provided, which returns the closing element to a closed starting position of the gas injector after an opening process. The gas injector further comprises, in particular, a bellows, which is part of a housing of the lubricant chamber, wherein a first end of the bellows is connected to the valve needle.The gas injector further comprises a sleeve that partially encloses both the valve needle and the armature pin. The sleeve is preferably cylindrical. The joint, which lies in a plane E perpendicular to the central axis XX, is surrounded by the sleeve. The sleeve has a damping device that dampens impact between the valve needle and the armature pin. Thus, the sleeve, which is a very cost-effective and simply constructed component, can provide an additional damping effect during the closing process, so that the valve needle no longer strikes the armature pin unhindered, but is decelerated by the sleeve.

[0005] The sleeve preferably acts as a hydraulic braking device, which, after the valve needle has been lifted off the armature pin during the opening process, drains lubricant in a defined manner through the sleeve during the closing process. This leads to a reduction in the movement speed of the valve needle, so that the valve needle strikes the armature pin at a lower impact speed, which can significantly reduce wear on both components.

[0006] The subclaims show preferred developments of the invention.

[0007] The damping device is preferably designed as a fluid damper, which provides damping by means of the lubricant. Thus, no additional components are required to provide the desired damping effect when the valve needle impacts the armature pin. The damping device is preferably implemented by a geometric design of the sleeve, particularly on an inner circumference of the sleeve.

[0008] The damping device preferably comprises at least one through-opening. Preferably, a plurality of through-openings are provided. Preferably, the through-openings all have the same cross-section. Alternatively, through-openings with different cross-sections are provided.

[0009] Preferably, a plurality of through-openings are arranged at different positions along an inner circumference of the sleeve. Preferably, the through-openings are all arranged in one or more planes E or inclined bores. Plane E is preferably located in the region of the gap between the valve needle and the armature pin. Preferably, the diameters of the through-openings are equal to or smaller than a maximum gap height during the opening process between the valve needle and the armature pin. Alternatively or additionally, the through-openings are arranged in a plane parallel to plane E.

[0010] Further preferably, the damping device comprises at least one groove on the inner circumference of the sleeve. The groove preferably runs parallel to a central axis.

[0011] Preferably, a plurality of grooves is provided on the inner circumference of the sleeve. More preferably, the plurality of grooves begin in plane E in the region of the gap between the valve needle and the armature bolt during the opening process. The groove preferably extends to one edge of the sleeve and is thus in fluid communication with the remaining lubricant chamber of the gas injector. The groove preferably intersects plane E.

[0012] Preferably, a groove extends from a first edge of the sleeve to a second, opposite edge of the sleeve. The groove is thus a through groove formed on an inner circumference of the sleeve from a beginning to an end and extending over the entire length of the sleeve.

[0013] Preferably, the sleeve is firmly connected to the valve needle. Alternatively, the sleeve is firmly connected to the anchor bolt or another stationary component.

[0014] Grooves on the inner circumference of the sleeve can be manufactured very easily and cost-effectively. Preferably, a plurality of grooves are formed parallel to one another. Alternatively, one groove can be designed as a spiral groove.

[0015] Further preferably, the sleeve of the gas injector also serves as a guide element for guiding the valve needle and / or the anchor bolt.

[0016] Further preferably, a liquid, in particular oil, and a gas, in particular air, are present in the lubricant chamber, wherein the sleeve is completely disposed in the liquid when the gas injector is mounted. The gas enables compensation for temperature-related volume changes of components and / or the liquid in the lubricant chamber.

[0017] Preferably, the valve needle and / or the armature pin are flat at the joint. This means that the contact surfaces of the valve needle and / or the armature pin are flat, without geometric shapes, but rather are designed as planar surfaces. Alternatively, the contact area is designed as a ball-to-plane contact or ball-to-ball contact. Short description of the drawings

[0018] A preferred embodiment of the invention will be described in detail below with reference to the accompanying drawings. In the drawing: Fig. 1 is a schematic sectional view of a gas injector according to a first embodiment of the invention in the closed state, and Fig. 2 a schematic, enlarged sectional view of the gas injector of Fig. 1. Preferred embodiment of the invention

[0019] The following is based on the Fig. 1 and Fig. 2 a gas injector 1 according to a first preferred embodiment of the invention is described in detail.

[0020] Fig. 1 shows the closed state of the gas injector 1. The gas injector 1 is designed to inject a gaseous medium, for example hydrogen, into a combustion chamber 13.

[0021] The gas injector 1 comprises a magnetic actuator 2, which moves an outwardly opening closing element 3 from the closed state to an open state.

[0022] The magnetic actuator 2 comprises an armature 20, an inner pole 21 and a coil 22.

[0023] The closing element 3 is constructed in two parts and comprises a valve needle 30, which seals against a sealing seat 5 in the closed state, and an armature pin 31. The armature pin 31 is rigidly connected to the armature 20. The valve needle 30 and the armature pin 31 are arranged in series and can be moved independently of one another. In the closed state, a first contact area 30a of the valve needle 30 rests against a second contact area 31a of the armature pin 31.

[0024] Thus, there is a joint between the first contact area 30a of the valve needle 30 and the second contact area 31a of the armature bolt 31. The joint is located in a plane E, which is perpendicular to a central axis XX of the gas injector.

[0025] The gas injector 1 further comprises a return element 6, which is operatively connected to the valve needle 30 in order to return this element from the open to the closed state.

[0026] Furthermore, the gas injector 1 comprises a main body 10 with a gas inlet 11, through which pressurized gas is supplied into the interior of the gas injector. A gas path 14 is indicated by the arrows in Fig. 1. The gas path 14 runs from the gas inlet 11 along the inner circumference of a housing sleeve 12 to the sealing seat 5 of the gas injector. Corresponding passages and openings are provided in the components of the gas injector for supplying the gas from the gas inlet 11 to the valve plate of the valve needle 30.

[0027] The gas injector 1 further comprises a lubricant chamber 4, which is filled with a liquid 40 and a gas 41. The gas injector 1 is arranged in a substantially vertical arrangement, so that the gas 41, as in Fig. 1 shown schematically, is located in an upper area of ​​the lubricant chamber 4 when assembled.

[0028] The lubricant chamber 4 is a closed hydraulic chamber which is filled with a lubricating fluid (lubricant) to lubricate moving parts of the gas injector 1. As can be seen from Fig. As can be seen in Figure 1, the armature 20 and the armature bolt 31 are arranged in the lubricant chamber 4. The return element 6 is also arranged in the lubricant chamber 4.

[0029] The lubricant chamber 4 is closed off from the gas path 14. Components present in the gas injector form a housing for the lubricant chamber 4. Furthermore, a bellows 42 is arranged at an end of the lubricant chamber 4 directed toward the combustion chamber, which bellows provides axial mobility for the closing element 3. As can be seen from Fig. 1, the bellows 42 is connected to the valve needle 30 with one end directed towards the combustion chamber 13, for example by means of a welded connection, and a second end of the bellows 42 facing away from the combustion chamber is connected to a housing component 15 of the lubricant chamber 4.

[0030] The gas injector 1 further comprises a sleeve 8, which is cylindrical in this embodiment. The sleeve 8 is arranged in the region of the joint between the valve needle 30 and the armature bolt 31 (see FIG. Fig. 2).

[0031] The sleeve 8 is firmly connected to the valve needle 30. As can be seen from Fig. As can be seen in Figure 2, the plane E intersects the sleeve 8.

[0032] The sleeve 8 further comprises a damping device 7. The damping device 7 comprises a plurality of through openings 71, in particular transverse bores in the sleeve 8, and a plurality of grooves 72 on the inner circumference of the sleeve 8.

[0033] The through openings 71 are formed in the plane E.

[0034] Fig. 2 shows an open state of the gas injector, whereby a reset of the valve needle 30 takes place. This is indicated by the arrow C in Fig. 2. In this state, a gap is present at the joint between the valve needle 30 and the armature bolt 31. Due to the return of the valve needle 30, the fluid located in this gap is displaced radially outwards. This is shown in Fig. 2 indicated by the arrows D.

[0035] The fluid displaced from the gap in the radial direction is, as in Fig. 2, on the one hand, into the through-holes 71 (arrows A) and the grooves 72 (arrows B). Depending on the geometry of the through-holes 71 and the grooves 72, a damping effect can be individually adjusted for the gas injector.

[0036] The through-openings 71 of this exemplary embodiment run perpendicular to the central axis XX of the gas injector. The grooves 72 of this exemplary embodiment run parallel to the central axis XX of the gas injector. The grooves 72 extend to an edge of the sleeve 8 facing away from the combustion chamber.

[0037] The through-openings 71 have a constant diameter. In this exemplary embodiment, all through-openings 71 have the same diameter. Further preferably, the geometry of all grooves 72 in this exemplary embodiment is also identical.

[0038] The fluid displaced from the gap thus passes through the through-holes 71 and the grooves 72 into the lubricant chamber 4 filled with fluid 40 and through the component 9 provided with through-holes in the direction of a compensation chamber 43 of the lubricant chamber. Fig. 1, gas 41 is present in the compensation chamber 43 in order to compensate for temperature-related volume changes of the components during operation of the gas injector by compressing the gas 41.

[0039] Furthermore, a braking device 16 is arranged in the lubricant chamber 4, which is designed to slow down an opening process of the closing element 3 and a closing process of the closing element 3. The braking device 16 enables, in particular, a reduced impact speed of the valve needle 30 against the sealing seat 5 and of the armature 20 against an armature stop. The braking device 16 acts independently of the damping device 7 between the valve needle 30 and the armature bolt 31.

[0040] Thus, the damping device 7, which is formed in the sleeve 8, allows for a defined control of the flow velocity of the fluid from the gap during the closing process. This defines the damping properties for the impact of the valve needle 30 against the armature pin 31. The controlled flow of the fluid from the gap results in a damper that is practically wear-resistant during operation.

[0041] The sleeve 8 can be provided as a separate component with integrated damper geometry, thus enabling adjustment-free installation of the damping device 7 into the gas injector. This protects the joint between the valve needle 30 and the armature bolt 31, preventing wear on these two components. This also has a positive effect on other components and their wear, which could occur due to tilting and / or hard impact of the valve needle 30 on the armature bolt 31.

Claims

[1] Gas injector for injecting a gaseous medium, comprising - a magnetic actuator (2) with an armature (20), an inner pole (21) and a coil (22), - a closing element (3) which opens and closes a gas path (14) at a sealing seat (5), wherein the closing element (3) comprises a valve needle (30) and an anchor bolt (31) firmly connected to the armature (20), - a closed lubricant chamber (4) filled with lubricant, in which the armature (20) and the anchor bolt (31) are arranged, - a return element (6) which returns the closing element (3) to a closed initial position, - a sleeve (8) which only partially encloses the valve needle (30) and the anchor bolt (31), - wherein a joint is formed between the valve needle (30) and the anchor bolt (31), - wherein the joint lies in particular in a plane E perpendicular to a central axis XX of the gas injector and is surrounded by the sleeve (8), and - wherein the sleeve (8) comprises a damping device (7) to dampen an impact between the valve needle (30) and the anchor bolt (31). [2] Gas injector according to claim 1, wherein the damping device is a fluid damper which provides damping by means of the lubricant of the lubricant chamber. [3] Gas injector according to one of the preceding claims, wherein the damping device comprises at least one through-opening (71) in the sleeve (8). [4] Gas injector according to claim 3, wherein the damping device (7) comprises a plurality of through openings (71) in the sleeve (8) which are arranged at different positions along an inner circumference of the sleeve (8). [5] Gas injector according to claim 4, wherein the plurality of through holes (71) are arranged in the plane E, or in a plane parallel to the plane E. [6] Gas injector according to one of the preceding claims, wherein the damping device (7) further comprises at least one groove (72) on the inner circumference of the sleeve (8). [7] Gas injector according to claim 6, wherein the groove (72) runs parallel to the central axis XX, or wherein the groove (72) is designed as a spiral groove. [8] Gas injector according to one of claims 6 or 7, wherein the groove (72) begins at the plane E and leads to an edge of the sleeve (8), or wherein the groove (72) intersects the plane E. [9] Gas injector according to claim 8, wherein the groove (72) leads from a first edge of the sleeve (8) to a second edge of the sleeve (8). [10] Gas injector according to one of the preceding claims, wherein the sleeve (8) is attached to the valve needle (30). [11] Gas injector according to one of the preceding claims, wherein the valve needle (30) and the anchor bolt (31) are flat at the joint.

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