Gas injector

Abstract

The present invention relates to a gas injector for injecting a gaseous medium, comprising: an actuator (9) with an armature (90), a coil (91) and an inner pole (92), a closing element (2) which is operatively connected to the armature (90) and which opens and closes a passage into a combustion chamber (10) at a sealing seat (4), a gas path (14) which leads from a gas inlet (7) to the sealing seat (4) through the gas injector, at least one first guide region (11) for guiding a component of the gas injector, and a lubricant reservoir (5) in which a lubricant is arranged, wherein the lubricant reservoir (5) has a connection opening (6) to the gas path (14) such that when the gaseous medium flows past, the gaseous medium takes up lubricant from the lubricant reservoir (5) via the connection opening (6) and supplies the first guide region (11) with lubricant.

Description

Prior ArtThe present invention relates to a gas injector for blowing a gaseous medium, such as hydrogen, natural gas, methane, LPG, ammonia or the like, into a combustion chamber of an internal combustion engine.Gas injectors are known from the prior art in different configurations. Compared with injectors for liquid fuels, gas injectors require significantly larger flow cross sections, since a volume of the gaseous medium is significantly larger at the same energy content than in the case of liquid fuels. Furthermore, in the case of gas injectors, there is the problem that, owing to the lack of lubricating properties of the gas to be injected, no lubrication of moving parts of the gas injector takes place. This can result in a wear problem at the seat of the gas injector and the guide regions of the gas injector of moving components. Furthermore, it has been found that the large gas flows frequently also carry very small particles which can lead to problems as far as jamming of the closing element at guide regions, in particular at guide regions for a closing element of the gas injector.Disclosure of the InventionThe gas injector according to the invention for blowing in a gaseous medium having the features of claim 1 has the advantage over the related art that wear on movable components of the gas injector can be significantly reduced. In particular, the present invention enables lubrication of movable components of the gas injector. Thus, a disadvantage of the dry gaseous medium to be injected can be compensated for. The gas injector according to the invention enables a reduction of coefficients of friction on guide surfaces of movable components. This is achieved according to the invention in that the gas injector has an actuator with an armature, a coil and an inner pole. The armature is operatively connected to a closing element which opens and closes a passage at a sealing seat of the gas injector. A gas path which leads from a gas inlet to the sealing seat through the gas injector determines a flow path of the gaseous medium through the gas injector. The gas injector further comprises at least one first guide region for guiding a component of the gas injector and a lubricant reservoir in which a lubricant is arranged. The lubricant reservoir has a connecting opening for a connection to the gas path in such a way that when the gaseous medium flows past, the gaseous medium receives lubricant from the lubricant reservoir via the connecting opening. In other words, during operation of the gas injector, the gaseous medium flows past the connecting opening of the lubricant reservoir and absorbs lubricant. The gaseous medium thus loaded then flows to the first guide region, so that the first guide region can be supplied with the lubricant. As a result, a coefficient of friction at the first guide region can be lowered and friction between the components can thus be reduced. Thus, due to the connection, which is open at all times, via the connecting opening between the lubricant reservoir and the gas path, lubricant can be removed from the lubricant reservoir when the gaseous medium flows past and brought to the corresponding locations in the gas injector, at which a reduction in friction is helpful. The first guide region is located in particular downstream of the connection opening of the lubricant reservoir in the direction of flow through the gas injector.The dependent claims show preferred developments of the invention.Particularly preferably, the connecting opening is designed as a capillary opening. The capillary opening preferably has a diameter of 5 μm to 10 μm. This makes it possible for very small amounts of lubricant to be able to be continuously discharged into the gas path over the service life of the gas injector. By selecting the diameter of the capillary opening, a metering quantity of lubricant which is entrained by the gas stream flowing past can be set very accurately.In order to ensure reliable lubrication of all movable parts of the gas injector, the lubricant reservoir is preferably arranged in a first third of the gas injector, in particular a first fifth, starting from a gas inlet into the gas injector. In this case, further preferably no movable components are arranged in the first third or first fifth of the gas injector.The lubricant of the lubricant reservoir is preferably liquid, in particular oil.Further preferably, an amount of the lubricant in the lubricant reservoir is selected such that a delivery of lubricant reaches up to a predetermined threshold value of a use of the gas injector. For example, the lubricant reservoir is designed such that the dispensing of lubricant is sufficient for at least one operation of the gas injector in an internal combustion engine of a vehicle for the first 1000 km driven. The lubricant reservoir thus provides lubrication for initial operation of the gas injector. Since in applications in the vehicle sector, in particular a compressor, for example at a gas filling station, is used, in which oil lubrication is present, certain oil components are frequently also obtained in the gaseous medium when filling with the gaseous medium, which oil components can then assume a lubrication task according to the threshold value.The first guide region of the gas injector is preferably designed for guiding the closing element at the sealing seat. Thus, in particular during the closing process of the gas injector, a coefficient of friction on the guide surface of the sealing seat can be reduced. This reduces wear of the closing element on the sealing seat and wear of the sealing seat itself. Further preferably, the gas injector comprises a second guide region which is configured for guiding the closing element.Further preferably, the gas injector comprises a second guide region for guiding the closing element. The second guide region is preferably a guide plate between the closing element and a housing component, for example a valve body, of the gas injector. Particularly preferably, the second guide region comprises two guide plates or three guide plates.The closing element is preferably formed in two parts with a valve needle and an armature pin which is firmly connected to the armature. The guide plates are preferably provided on the valve needle and have apertures in order to feed the gaseous medium through the apertures as far as the open aperture at the sealing seat.Further preferably, the gas injector further comprises a third guide region for guiding the armature. The armature has, in particular on its outer circumferential surfaces, guide regions which can be lubricated by the medium-laden gaseous medium.Further preferably, the gas injector has a fourth guide region for guiding a restoring element, in particular a spring element. The spring element is preferably a cylinder spring which is arranged in a hollow cylindrical space. By means of the gaseous medium loaded with lubricant, a coefficient of friction on the outer circumference of the spring element can be adapted to the respectively desired branch of use.Further preferably, the guide region or regions are all arranged downstream of the connection opening of the lubricant reservoir in the flow direction through the gas injector.Further preferably, the gaseous medium is set in turbulence in the region of the connecting opening, in particular by deflecting it at a deflecting region, in order to facilitate the absorption of lubricant from the connecting opening to the lubricant reservoir.Brief Description of the DrawingsA preferred embodiment of the invention is described in detail below with reference to the accompanying drawings. In the drawing, the following is: FIG. 1 shows a schematic sectional view of a gas injector according to a preferred exemplary embodiment of the invention.Preferred Embodiments of the InventionIn the following, a gas injector 1 according to a first preferred exemplary embodiment of the invention is described in detail with reference to FIG. 1.FIG. 1 shows a gas injector 1 in cross section in the closed state. The gas injector 1 comprises a magnetic actuator 9 for moving a closing element 2 from the closed position shown in FIG. 1 into an open position. In this exemplary embodiment, the gas injector 1 is an outwardly opening injector in which the closing element 2 opens in the direction of a combustion chamber 10.The closing element 2 of this exemplary embodiment is formed in two parts with a valve needle 20 and an armature pin 21.The armature pin 21 bears loosely against the valve needle 20. The armature pin 21 is thereby firmly connected to an armature 90 of the magnetic actuator. In addition to the armature 90, the magnetic actuator 9 further comprises a coil 91 and an inner pole 92; the reference symbol 93 denotes an armature gap which is overcome when the gas injector is opened. The armature 90 then abuts a stop surface of the inner pole 92 in the completely open state of the gas injector. A so-called full stroke in the axial direction X-X of the gas injector 1 is then carried out and the gas injector with the largest outlet cross section is opened at a sealing seat 4.The closing element 2 closes the gas injector 1 at the sealing seat 4 in the closed state.A gas path 14 is schematically illustrated in FIG. 1 by the arrows. The gas path 14 begins at an inlet 7, which is located at an opposite end of the sealing seat 4. As can be seen from FIG. 1, the gas path 14 extends past the magnetic actuator 9 on its outer periphery and through correspondingly formed apertures in various components of the gas injector as far as in front of the sealing seat 4.A first valve disk 22 and a second valve disk 23 are provided on valve needle 20 for guiding valve needle 20. The two valve disks 22, 23 are guided on an inner side 32 of a valve body 3, which is part of the housing of the gas injector. In the two valve disks 22, 23, apertures for the gas path 14 are correspondingly formed. Fixed to a further valve disk 24 of the valve needle 20 is a bellows 15, which is firmly connected at an end directed toward the inlet 7 to a hollow cylindrical component 16. A restoring element 17 for restoring the closing element 2 is arranged in the hollow cylinder component 16.Thus, the gas injector 1 has a first guide region 11 at the sealing seat 4. In particular during the closing process of the closing element 2, contact and a sliding process occur between the guide surfaces of the closing element and the sealing seat 4 until the closing element finally bears against the sealing seat 4 in the end position and seals the gas injector.The gas injector 1 further has a lubricant reservoir 5, which is filled with a lubricant, in particular oil. The lubricant reservoir 5 is connected to the gas path 14 via a capillary connecting opening 6.It is thus possible for the gaseous medium to be blown in, which flows past the connecting opening 6, to take up lubricant from the lubricant reservoir 5 via the connecting opening 6. This gaseous medium thus loaded with lubricant is then supplied up to the first guide region 11 and reduces friction at the sealing seat 4 during a closing process.The gas injector 1 further comprises a second guide region 12 which is formed between the first and second valve disks 22, 23 and the valve body 3. Here too, the gaseous medium loaded with lubricant is used to reduce friction between the two components.Furthermore, the gas injector 1 has a third guide region 13 which is formed between the armature 90 and a housing component 94. Here too, owing to turbulence which is generated at a 90° deflection 7 aof the gas path 14, lubricant can be released to the gaseous medium and reduce friction at the guide region of the armature 90.The connecting opening 6 has an opening which is arranged adjacent to the deflection region 7 aof the gas path from a gas path direction directed in the axial direction X-X into a gas path direction deflected by 90°.Thus, in particular wear on the sealing seat 4 and on the closing element 2 both on a sealing seat plate 20 aof the closing element 2 and on the two valve plates 22, 23 for guiding the closing element can be significantly reduced. The size of the lubricant reservoir 5 is selected such that lubricant can be discharged through the connecting opening 6 in particular as long as a first operation or a running-in of an internal combustion engine in which the gas injector is used is concluded. Thus, in particular, the relatively large lifting movements during the opening and closing process of the closing element 2 cannot lead to large permanent damage to the sealing seat. Thus, the problem of the dry, gaseous medium can be solved by the skillful arrangement of the lubricant reservoir 5 on the gas path 14 of the gas injector.It is noted that the invention is applicable to all different types of sealing seats and valve needles, in particular to outwardly opening valve needles or inwardly opening valve needles. The sealing seat can be designed as a flat seat or as a conical seat, in each case in particular also as metallic seats.Further preferably, an opening of the connection region to the lubricant reservoir is arranged at a deflection region of the gas path 14.

Claims

Gas injector for blowing in a gaseous medium, comprising: - an actuator (9) having an armature (90), a coil (91) and an inner pole (92), - a closing element (2) which is operatively connected to the armature (90) and opens and closes a passage into a combustion chamber (10) at a sealing seat (4), - a gas path (14) which leads from a gas inlet (7) to the sealing seat (4) through the gas injector, - at least one first guide region (11) for guiding a component of the gas injector, and - a lubricant reservoir (5) in which a lubricant is arranged, - wherein the lubricant reservoir (5) has a connection opening (6) to the gas path (14) in such a way that, that, when the gaseous medium flows past, the gaseous medium receives lubricant from the lubricant reservoir (5) via the connecting opening (6) and supplies the first guide region (11) with lubricant.Gas injector according to Claim 1, wherein the connecting opening (6) is a capillary opening, in particular having a diameter of 5 μm to 10 μm.Gas injector according to one of the preceding claims, wherein the lubricant reservoir (5) is arranged in a first third, in particular first fifth, of the gas injector starting from the gas inlet (7) of the gas injector.Gas injector according to one of the preceding claims, wherein the lubricant in the lubricant reservoir (5) is liquid and is in particular oil.Gas injector according to one of the preceding claims, wherein the first guide region (11) between the sealing seat (4) and the closing element (2) is configured to guide the closing element (2) into the sealing seat (4).Gas injector according to one of the preceding claims, further comprising a second guide region (12) for guiding the closing element on a valve body (3).Gas injector according to Claim 6, wherein the second guide region (12) is formed between a valve disk (22, 23) connected to the closing element and the valve seat (3).Gas injector according to one of the preceding claims, further comprising a third guide region (17) on the armature (90), configured to guide the armature (90).Gas injector according to one of the preceding claims, wherein an orifice of the connecting opening (6) is arranged at a deflection region (7a) of the gas path (4).

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