Gas injector for injecting gas fuel

Abstract

The invention relates to a gas injector (10) for blowing in a gaseous fuel, comprising an electromagnetic actuator (68) for actuating an armature (66), the armature (66) being coupled at least indirectly to a closing element (34) which releases and closes a gas path (35) at a valve seat (29), the armature (66) being arranged in a closed lubricant chamber (60) filled with lubricant, the closing element (34) being arranged in the closed lubricant chamber (60), and the closing element (34) being arranged in the closed lubricant chamber (60). According to the invention, the closing element (34) is a lubricant which ensures lubrication of the armature (66), and wherein the closing element (34) is a valve needle (30; 30a), said valve needle (30; 30a; 30b; 30c) having a part of the valve needle (30; 30a) extending in the direction of the longitudinal axis (32) and attached to each other, at least two elements (36; 36a, 37; 37a) for a motor vehicle.

Description

Technical Field

[0001] The invention relates to a gas injector for injecting gaseous fuel, in particular hydrogen or natural gas or the like, into a combustion chamber, which, in addition to reduced wear, also allows an advantageous production of the valve needle. Background Art

[0002] Gas injectors are known from the prior art in various configurations. In principle, the problem with such gas injectors is that, due to the gaseous medium to be injected, lubrication cannot be achieved by means of this medium, as is possible, for example, in fuel injectors that inject gasoline or diesel. For this reason, the applicant's subsequent publication DE 10 2021 200 689 A1 discloses arranging the armature of the electromagnetic actuator in a lubricant chamber filled with lubricant.

[0003] Another problem with this gas injector is the manufacture of the valve needle, which releases the inlet for blowing gas into, for example, the combustion chamber of an internal combustion engine. Also in principle, this valve needle has a relatively large structural length. However, this valve needle with a relatively large structural length can only be manufactured with high expenditure, especially in terms of the desired coaxiality of the valve needle with the upper needle guide component and the lower needle guide component. The problem here is, for example, the deformation of the valve needle (Verzug) that occurs in this potential generation during heat treatment or grinding after heat treatment. For this reason, the valve needle known from the above-mentioned DE 10 2021 200689A1 has two elements joined in the axial direction, which form the valve needle, wherein the valve needle axially rests on the armature column connected to the electromagnetic armature. The two elements of the valve needle are connected to each other, for example, by a press fit. The disadvantage here is the high engagement, and the engagement force may cause the formation of debris during the extrusion process. In addition, the diameter of the elements of the valve needle must be relatively large in order to achieve a sufficiently high extrusion force. This in turn causes the valve needle to be relatively heavy. Summary of the invention

[0004] The gas injector according to the invention for injecting gaseous fuels having the features of claim 1 has the advantage that it allows a relatively simple production of the valve needle and at the same time a low weight of the valve needle.

[0005] The invention is based on the idea that the two elements of the valve needle are connected to one another via a threaded connection, whereby in particular high pressing forces are not required between the elements of the valve needle, and thus also large diameters of the elements of the valve needle are not required.

[0006] Therefore, against the background of the above explanations, the gas injector according to the invention for blowing in gaseous fuel comprises an electromagnetic actuator for actuating an armature, wherein the armature is at least indirectly coupled to a closing element which releases and closes a gas path at a valve seat, wherein the armature is arranged in a closed lubricant chamber filled with lubricant, wherein the lubricant ensures lubrication of the armature, wherein the closing element is part of a valve needle having at least two elements which extend in the direction of the longitudinal axis of the valve needle and are attached to one another, and wherein the at least two elements are connected to one another in the direction of the longitudinal axis by a threaded connection.

[0007] Advantageous embodiments of the gas injector according to the invention for injecting gaseous fuels are set forth in the dependent claims.

[0008] The threaded connection preferably has an internal thread on the closing element as the first element and an external thread on the second element of the valve needle connected to the closing element. This takes into account the following situation: the closing element usually has a larger diameter than the (second) element of the valve needle connected to the closing element, which element is used to transmit the force from the armature pin to the closing element.

[0009] Furthermore, it is particularly preferred that at least two elements of the valve needle cooperate with a preferably tubular clamping body which radially surrounds the second element, wherein the clamping body is designed to exert a compressive force on the threaded connection in the direction of the longitudinal axis which acts in the direction of the closing element. Such a configuration of the threaded connection or the valve needle allows a particularly rigid valve needle, since the clamping body coupled to the two elements of the valve needle radially surrounds the two elements and thus also increases the diameter of the valve needle. Furthermore, the clamping body ensures that the threaded connection between the two elements of the valve needle will not loosen during the service life of the gas injector.

[0010] In a preferred embodiment of such a clamping body, the clamping body is fixed at least indirectly by means of a threaded connection in the axial direction to the valve needle on the side facing away from the closing element.

[0011] In addition to the actual connection between the two elements of the valve needle, it is also important that the longitudinal axes of the two elements of the valve needle are oriented relative to each other or, viewed as a whole, form a common longitudinal axis. For this purpose, it is preferably provided that centering means are formed on the clamping body and the closing element, which serve to align the two elements of the valve needle in the direction of the longitudinal axis.

[0012] In a first structural embodiment of such a centering means, it is provided that the centering means has a first region in the form of a ball segment, which is formed on the clamping body or the closing element and which interacts with a second region of complementarily formed form on the closing element or the clamping body.

[0013] As an alternative thereto, it can also be provided that the centering means comprises an axial guide and a conical seat and a sealing edge cooperating with the conical seat between the clamping body and the closing element.

[0014] In order to construct a lubricant chamber in the gas injector that is sealed or closed relative to the gas path, it is also provided that the clamping body is connected to a bellows-shaped element, which radially surrounds the clamping body over a portion of its length and is connected to an element fixed relative to the housing, wherein the bellows-shaped element limits and seals the lubricant chamber.

[0015] In order to actuate the valve needle, it is provided that the armature has an armature stub or is connected to an armature stub, one end face of which rests against the facing end face of the valve needle.

[0016] In order to improve the damping properties during operation of the valve needle, it is also advantageous if the armature interacts with a damping device arranged on the side facing away from the valve needle.

[0017] Further advantages, features and details of the invention emerge from the following description of preferred exemplary embodiments of the invention and from the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A schematic longitudinal section showing a gas injector for blowing gaseous fuel into a combustion chamber, and

[0019] Figure 2 The longitudinal section also shows Figure 1 Part of a gas injector in case of a modified connection of two elements of a valve needle.

[0020] Identical elements or elements having the same function are provided with the same reference symbols in the figures. DETAILED DESCRIPTION

[0021] exist Figure 1 The gas injector 10 shown in the figure is used to inject gaseous fuel, in particular hydrogen or natural gas, etc., into a combustion chamber (not shown) of an internal combustion engine. The gas injector 10 has a housing 12 constructed in multiple parts, which has a valve body 14. The valve body 14 is connected to the upper end piece 20 of the housing 12 via a mounting sleeve 16 and a further sleeve 18. The connection between the mounting sleeve 16 and the sleeve 18 and the connection between the sleeve 18 and the end piece 20 is carried out in a known manner by a clamping nut connection (Spannmutterverbindung) not shown in detail.

[0022] The gaseous fuel is supplied via a supply bore 22 formed in the mounting sleeve 16, which opens into an annular chamber 23 between the valve body 14 and the mounting sleeve 16. The gaseous fuel enters a pressure chamber 25 in the valve body 14 via an obliquely extending bore 24. The pressure chamber 25 is connected via an axial bore 26 to a valve chamber 28, which forms a valve seat 29 on the end face of the gas injector 10 facing away from the end piece 20. The supply bore 22, the annular chamber 23, the bore 24 and the pressure chamber 25 together with the bore 26 and the valve chamber 30 form a gas path 35 for supplying the gaseous fuel from the supply bore 22 into the combustion chamber.

[0023] The valve seat 29 cooperates with a multi-part valve needle 30 which is arranged to be movable back and forth along a longitudinal axis 32. Figure 1 In the raised position shown in FIG, valve needle 30 closes valve seat 29 by means of closing element 34 of valve needle 30 .

[0024] The valve needle 30, which is formed by the closing element 34 as the first element 36, also has a second element 37, which is substantially pin-shaped and is arranged flush with the first element 36, i.e. flush with the longitudinal axis 32. The two elements 36, 37 of the valve needle 30 are connected via a threaded connection 40. The threaded connection 40 comprises an internal thread 42 formed on the first element 36 or the closing element 34, which cooperates with an external thread 43 formed on the second element 37.

[0025] The two elements 36, 37 of the valve needle 30 are radially surrounded by a tubular clamping body 44, which consists of two elements, namely an attachment part 45 and a guide part 46, which are attached to each other in the axial direction or in the direction of the longitudinal axis 32. The attachment part 45 has a spherical segment-shaped area 48 on the side facing the first element 36 or the closing element 34, which cooperates with a complementary area 49 on the closing element 34 or the first element 36. The two areas 48, 49 are components of a centering device 50, wherein the centering device 50 is used to ensure the coaxial arrangement or flush arrangement of the two elements 36, 37 of the valve needle 30. For this purpose, it is also provided that the attachment part 45 is exerted in the direction of the first element 36 or the closing element 34 with an axial force generated by the clamping body 44. For this purpose, the guide part 46 is connected or clamped to the second element 37 by means of a clamping nut 51 as part of a threaded connection and by means of an external thread 52 formed on the second element 37 of the valve needle 30. Furthermore, first element 36 of valve needle 30 has a section 54 of reduced diameter which acts in the manner of an expansion screw, ie, has a greater elasticity than other sections of first element 37 .

[0026] The attachment part 45 is surrounded radially by an attachment ring 56 fixed relative to the housing and used for radial guidance of the attachment part 45. In addition, the attachment part 45 has an annular edge 57 on the lower end face facing the first element 36, to which a metal bellows 58 is fastened, which surrounds the attachment part 45 in the radial direction. The bellows 58 is in turn connected to the upper attachment ring 56 on a section with reduced diameter. The bellows 58 delimits a lubricant chamber 60 and seals it toward the gas path 35, wherein a lubricant (not shown), for example lubricating oil, is arranged in the lubricant chamber 60.

[0027] The guide member 46 is radially surrounded by a sealing ring 62. A valve closing spring 64 is supported between the sealing ring 62 and the guide member 46. Figure 1 In the closed position shown in FIG. , a spring force is applied to the valve needle 30 .

[0028] Viewed in the direction of the longitudinal axis 32, the second element 37 of the valve needle 30 ends just above the clamping nut 51. There, the valve needle 32 rests with its upper end face against the lower end face of the armature pin 65. The armature pin 65 is connected to an armature 66, which is part of a magnetic circuit with an electromagnetic actuator 68.

[0029] In addition to the armature 66, the electromagnetic actuator 68 arranged in the region of the sleeve 18 comprises an inner pole 69 for guiding the armature pin 65, a solenoid coil 70 and an outer pole 72. The solenoid coil 70 can be powered via an attached cable 74. When the solenoid coil 70 is energized, an opening force acting in the direction of the valve needle 30 is exerted on the armature 66, which opens the valve needle 30 from the Figure 1 The closed position shown in FIG. 1 is moved into its open position for injecting gaseous fuel.

[0030] The armature 66 has a pin-shaped extension 75 on the side opposite to the armature pin 65, which cooperates with a travel stop 76, which is arranged in a fixed position in a blind hole in the attachment part 20. A return spring 77 is supported between the travel stop 76 or the attachment part 20 and the upper end face of the armature 66, and presses the armature 66 in the direction of the inner pole 69. The return spring 77 is a component of a damping device 80 for the armature 66. The area in which the armature 66 and the damping device 80 are arranged is arranged in the lubricant chamber 60, so that the lubricant arranged in the lubricant chamber 60 is used for armature guidance or for lubricating the armature 66, and thus also reduces or prevents wear of the armature 66. In order to ensure the supply of lubricant to the armature chamber 81, the armature 66, the inner pole 69, the sealing ring 62 and the attachment ring 56 have holes or through-holes 82 to 85 extending in the direction of the longitudinal axis 32.

[0031] exist Figure 2, a modified fastening or arrangement between the two elements 36a, 37a of the valve needle 30a is shown. Here, a conical seat 86 is formed on the clamping body 44 or the attachment part 45a, which cooperates with a sealing edge 88 on the first element 36a. In addition, the first element 36a extends with a tubular projection 90 into an inner bore 92 of the attachment part 45a, so that the centering means 50a forms an axial guide between the first element 36a and the attachment part 45a.

[0032] The gas injector 10 thus described may be modified or altered in various ways without departing from the inventive concept.

Claims

1. A gas injector (10) for injecting gaseous fuel, comprising an electromagnetic actuator (68) for operating an armature (66), wherein: The armature (66) is at least indirectly coupled to a closing element (34), which releases and closes a gas path (35) at a valve seat (29), wherein the armature (66) is arranged in a closed lubricant chamber (60) filled with lubricant, wherein the lubricant ensures lubrication of the armature (66), wherein the closing element (34) is part of a valve needle (30; 30a), which has at least two elements (36; 36a, 37; 37a) extending in the direction of a longitudinal axis (32) of the valve needle (30; 30a) and attached to each other, and wherein the at least two elements (36; 36a, 37; 37a) are connected to each other in the direction of the longitudinal axis (32) by a threaded connection (40).

2. The gas injector according to claim 1, characterized in that The threaded connection (40) has an internal thread (42) on the closing element (34) as a first element (36; 36a) and an external thread (43) on a second element (37; 37a) connected to the closing element (34).

3. The gas injector according to claim 1 or 2, characterized in that: The at least two elements (36; 36a, 37; 37a) of the valve needle (30; 30a) act together with a clamping body (44), preferably a tubular clamping body, which radially surrounds the second element (37; 37a), wherein the clamping body (44) is designed to apply a squeezing force to the threaded connection (40) in the direction of the longitudinal axis (32) so as to act in the direction of the closing element (34).

4. The gas injector according to claim 3, characterized in that The clamping body (44) is fixed to the valve needle (30; 30a) at least indirectly by means of a threaded connection in the axial direction on the side facing away from the closing element (34).

5. The gas injector according to claim 3 or 4, characterized in that: Centering means (50; 50a) are formed on the clamping body (44) and the closing element (34), which serve to coaxially align the closing element (34) and the second element (37; 37a) in the direction of the longitudinal axis (32).

6. The gas injector according to claim 5, characterized in that The centering means (50) has a first area (48) in the form of a ball segment, which is formed on the clamping body (44) or the closing element (34) and interacts with a complementary second area (49) on the closing element (34) or the clamping body (44).

7. The gas injector according to claim 5, characterized in that The centering means (50a) comprises an axial guide and a conical seat (86) between the clamping body (44) and the closing element (34) as well as a sealing edge (88) cooperating with the conical seat (86).

8. The gas injector according to any one of claims 3 to 7, characterized in that The clamping body (44) is connected to a bellows (58) which radially surrounds the clamping body (44) over a partial region of its length and is connected to an element (56) fixed relative to the housing, wherein the bellows (58) delimits and seals the lubricant chamber (60).

9. The gas injector according to any one of claims 1 to 8, characterized in that The armature (66) is connected to an armature column (65), one end face of which bears against a facing end face of the valve needle (30; 30a).

10. The gas injector according to any one of claims 1 to 9, characterized in that The armature (66) cooperates with a damping device (80).

Images