Supply assembly for a hydrogen internal combustion engine

Abstract

The invention relates to a supply assembly (1) for an internal combustion engine (50) powered with gaseous fuel such as hydrogen. In order to provide effective means for lubrication of a hydrogen internal combustion engine, the invention provides that the supply assembly (1) comprises a lubricating device (10) with - a gas duct (15) for conveying a gas stream (F) containing hydrogen gas from an inlet opening (16) to an outlet opening (17), - a lubricant cavity (27) that is adapted to contain liquid lubricant (L), and - a separator body (20) with a porous dispenser wall (21) comprising a plurality of dispenser apertures, the dispenser wall (21) partially defining the lubricant cavity (27) and being interposed between the lubricant cavity (27) and a lubricating portion (15.3) of the gas duct (15), wherein the gas duct (15) is adapted to convey the gas stream (F) at least partially through the lubricating portion (15.3) along the dispenser wall (21), and the dispenser wall (21) is adapted to release lubricant (L) through the dispenser apertures into the lubricating portion (15.3) in response to an underpressure in the lubricating portion (15.3) with respect to the lubricant cavity (27).

Description

SUPPLY ASSEMBLY FOR A HYDROGEN INTERNAL COMBUSTION ENGINETECHNICAL FIELD

[0001] The present invention relates to a supply assembly for a hydrogen internal combustion engine.BACKGROUND OF INVENTION

[0002] For automotive applications, hydrogen engines are considered as a promising alternative to gasoline or diesel engines since the emissions from a hydrogen engine consist mainly of water. However, the usage of “dry” hydrogen, i.e., without any additional lubricant, may create a wear risk on the components of the engine system. All moving components in the system, e.g., pressure regulators, injectors etc., are prone to wear. In a fuel-cell based system, hydrogen must be dry to be compatible with the fuel cell stack, but in this case the pressure of the system is lower, which induces less stress and wear. In an engine system with an internal combustion engine, lubrication is imperative, though. It would be desirable to create a mist consisting of fine droplets, which is carried by the hydrogen flow through the circuit, from the injection point toward the injector seat. Aggregation of lubricant droplets should be avoided, i.e., lubricant droplets should not collapse together to create larger drops. Such larger lubricant drops would be detrimental to various components of the system. Lubricant, if accumulated, may create a sticking force on components like a pressure regulator, a purge valve or moving parts of a fuel injector.TECHNICAL PROBLEM

[0003] It is thus an object of the present invention to provide effective means for lubrication of a hydrogen internal combustion engine.

[0004] This problem is solved by a supply assembly according to claim 1.GENERAL DESCRIPTION OF THE INVENTION

[0005] The invention provides a supply assembly for an internal combustion engine operating with gaseous fuel such as hydrogen. As will be explained below, the supply assembly comprises at least one component that serves to supply the engine, specificallyto supply the engine with gaseous fuel and lubricant. The supply assembly comprises a lubricating device, which includes the possibility that the lubricating device is the only component of the supply assembly. The function of the lubricating device is to add lubricant to the gaseous fuel that is conveyed towards the engine. It could also be referred to as a lubricant-adding device.

[0006] In the following, the term 'gas’ means gaseous fuel, in particular a dry gas such as e.g. hydrogen or CNG. The term “gaseous fuel” generally includes combustible fluids which are in their gaseous state when exposed to nominal operating conditions of the injector and the engine, e.g. pressure and temperature. Regarding more specifically hydrogen as gaseous fuel for an ICE, it typically consists of a gas with at least 90% hydrogen (H2), preferably pure hydrogen with no more than 2% impurities.

[0007] The lubricating device comprises a gas duct for conveying a gas stream, in particular containing hydrogen gas, from an inlet opening to an outlet opening. It is understood that in operational state, the gas duct is - normally indirectly - connected to the engine to supply it with gas. The gas stream contains hydrogen gas (H2), but may also contain other components, in particular other gases, but also possibly liquid and / or solid components that are present as droplets or aerosols, or particles, respectively. The gas duct may be straight and may be at least partially symmetrical with respect to an axis, but it may in general have other shapes, too. In operational state, the gas stream enters the gas duct through the inlet opening and exits the gas duct through the outlet opening. Insofar, the inlet opening is disposed upstream of the outlet opening. In operational state, both the inlet opening and the outlet opening can be connected to additional gas-guiding components, upstream or downstream of the gas duct, respectively. It is within the scope of the invention that the gas duct originates from a plurality of inlet openings and / or leads to a plurality of outlet openings. Such a “branched” configuration is not common, though.

[0008] The lubricating device also comprises a lubricant cavity that is adapted to contain liquid lubricant. Normally, the liquid lubricant can also be referred to as a lubricating oil or simply oil. Its function is to provide lubrication to at least one component of the engine and / or the supply system. Various lubricants can be used in the inventive supply system, which may comprise natural and / or artificial components. While the lubricant is referred to as “liquid”, it is not ruled out that it may comprise minor amounts of solid particles, either as additives or as (unwanted) impurities. The lubricant cavity is adapted to contain this lubricant. However, the lubricant cavity is not completely closed, as will be explained in the following.

[0009] Further, the lubricating device comprises a separator body with a porous dispenser wall comprising a plurality of dispenser apertures, the dispenser wall partially defining the lubricant cavity and being interposed between the lubricant cavity and a lubricating portion of the gas duct. The gas duct comprises a lubricating portion, which may also be referred to as a lubricant-adding portion. It is normally only a part of the gas duct. The separator body comprises the dispenser wall which explicitly includes the possibility that the dispenser wall constitutes the entire separator body. The dispenser wall is porous in that it comprises a plurality of dispenser apertures, which are through-openings that traverse the dispenser wall. While the number of dispenser apertures is not limited within the scope of the invention, the dispenser wall normally comprises at least 100, at least 1000 or at least 10,000 or at least 100,000 dispenser apertures. The dispenser wall is interposed between the lubricant cavity and the lubricating portion. In other words, the lubricating portion of the gas duct is separated from the lubricant cavity by the dispenser wall. Accordingly, lubricant cannot flow freely from the lubricant cavity into the lubricating portion, but due to the dispenser apertures, the lubricating portion is not completely separated from the lubricant cavity.

[0010] The gas duct is adapted to convey the gas stream at least partially through the lubricating portion along the dispenser wall, and the dispenser wall is adapted to release lubricant through the dispenser apertures into the lubricating portion in response to an underpressure in the lubricating portion with respect to the lubricant cavity. The gas duct is designed so that in operational state, when the gas stream flows from the inlet opening to the outlet opening, at least a part of the gas stream flows through the lubricating portion along the dispenser wall. One could also say that the gas stream (partially) passes over / through the dispenser wall. This, in turn, leads to a non-zero dynamic pressure and a reduction of the static pressure in the lubricating portion near the dispenser wall. The dispenser wall is adapted to release lubricant through the dispenser apertures into the lubricating portion in response to this underpressure. In other words, if no underpressure is present, no lubricant is released into the lubricating portion. The underlying principle is that if the size of the apertures is chosen properly, the surface tension between the lubricant in a dispenser aperture and the atmosphere in the lubricating portion prevents lubricant from entering the lubricating portion as long as there is no underpressure in the lubricating portion. If, however, there is a (significant) under pressure due to a nonzero velocity of the gas stream, the forces resulting from the pressure difference can overcome the forces resulting from surface tension so that lubricant is released from the respective dispenser aperture. Specifically, a droplet can be released with a diameter that is comparable to the size of the respective dispenser aperture. Accordingly, the lubricant can be dispensed into the lubricating portion as a plurality of droplets, i.e. , it can be atomised. This lubricant mistcan then be carried by the gas stream to any components downstream of the lubricating device, thus providing a desired lubricating effect.

[0011] The inventive lubricating device has several advantages. On the one hand, it allows at least some control over the size of the droplets through the size of the dispenser apertures, to provide a mist. Therefore, the risk of forming too large droplets is minimized. On the other hand, the droplets can be formed over the entire area of the dispenser wall. Thus, the amount of lubricant that is dispersed in the gas stream can be increased by increasing the size of the dispenser wall. Also, droplets originating from different regions of the dispenser wall are unlikely to collide and agglomerate after formation. It should further be noted that the skilled person will know how to adapt the aperture (mesh) density and size to control the quantity of lubricant passing through the dispenser wall into the gas stream.

[0012] For optimum function of the dispenser wall, a certain size range for the dispenser apertures has been found advantageous. Specifically, at least a majority of the dispenser apertures may have a size between 2 and 30 pm, preferably between 5 and 20 pm. In this context, the majority corresponds to more than 50%, preferably more than 80%, more preferably more than 95%. The size may correspond to a diameter of the respective dispenser aperture, if the dispenser aperture has a circular cross-section. More generally, the size corresponds to the maximum dimension of the aperture along the surface of the dispenser wall. If a significant number of dispenser apertures is below the specified range, this may impede the flow of the lubricant through the aperture. If a significant number of filter apertures is above the specified range, this may cause lubricant to unwantedly enter the lubricating portion, e.g., simply by force of gravity. In other words, the lubricant might simply drip into the gas duct in an uncontrolled way. It should be understood that the optimum size may generally depend on the properties of the lubricant, specifically on its surface tension.

[0013] In general, various components of the supply assembly and / or the engine can be detrimentally affected by foreign particles in the gas stream, wherein “particles” relates to solid particles, but also includes liquid particles, i.e., droplets. The supply assembly comprises a porous filter wall for removing contaminant particles from the gas stream, the filter wall comprising a plurality of filter apertures and being disposed in the gas duct upstream of the lubricating portion. While the number of filter apertures is not limited within the scope of the invention, the filter wall normally comprises at least 100, at least 1000 or at least 10,000 or at least 100,000 filter apertures. Every filter aperture traverses the filterwall, thus representing a through-opening. The filter wall is disposed in the gas duct, normally so that the entire gas stream passes through the filter wall. It is disposed upstream of the lubricating portion, so that no lubricant droplets can be removed by the filter wall or can contaminate the filter wall, respectively. As a rule, the lubricating device comprises the filter wall.

[0014] In order to remove any particles that could be harmful for the engine and / or the supply system itself, a certain size range for the filter apertures has been found advantageous. Specifically, at least a majority of the filter apertures may have a size between 1 and 15 pm, preferably between 2 and 10 pm. As explained above, the majority corresponds to more than 50%, preferably more than 80%, more preferably more than 95%. The size may correspond to a diameter of the respective filter aperture in case of a circular cross-section. More generally, the size corresponds to the maximum dimension of the aperture along the surface of the filter wall. If a significant number of filter apertures is below the specified range, this may lead to excessive flow resistance. If a significant number of filter apertures is above the specified range, this may detrimentally affect the filter properties, i.e., too many particles may pass through the filter wall unhindered.

[0015] The dispenser wall and the filter wall are connected as parts of the separator body. The separator body is a single, normally rigid element. It can be made from a single piece of material (e.g., metal) or it could be made of several elements that are rigidly coupled, e.g., by welding or bonding or sintering. Either way, the dispenser wall and the filter wall are parts or regions of the separator body. One could also refer to them as a dispenser portion and a filter portion, respectively. Preferably the dispenser wall and the filter wall form distinct regions of the separator that are axially spaced along the gas flow axis, the filter wall being preferably located upstream. It will be understood that this embodiment facilitates the assembly of the lubricating device, since the two walls do not have to be installed separately. Within the separator body, the dispenser wall could be directly adjacent to the filter wall, or the two walls could be spaced apart. In the latter case, there could e.g., be a solid portion, without apertures, in between.

[0016] According to one embodiment, the dispenser wall extends at least partially circumferentially around a flow axis that traverses the lubricating portion, and at least a portion of the lubricant cavity extends at least partially circumferentially around the dispenser wall. In general, the flow axis doesn’t have to be identical to a flow direction of the gas stream, but the gas duct normally extends along the flow axis and is adapted to convey the gas stream along the flow axis. The dispenser wall extends at least partiallycircumferentially around the flow axis, wherein “partially circumferentially” refers to less than 360°, but normally at least 180° or at least 270°. The dispenser wall can be at least partially parallel to the flow axis. It may be at least partially cylindrical, with the flow axis corresponding to a symmetry axis of the dispenser wall. The flow axis traverses the lubricating portion, i.e., the lubricating portion is disposed around the flow axis. With respect to the flow axis, the lubricating portion is at least partially surrounded by the dispenser wall. The dispenser wall, in turn, is at least partially surrounded by at least a portion of the lubricant cavity. Accordingly, the lubricating portion is closest to the flow axis, with the dispenser wall following radially outside of the lubricating portion, and the (portion of the) lubricant cavity following outside of the dispenser wall. If the separator body comprises a filter wall, this may also be at least partially parallel to the flow axis and may at least partially be cylindrical.

[0017] Another embodiment provides that the lubricant cavity comprises an inner portion that is disposed within a main body and is disposed adjacent to the dispenser wall, and an outer portion that is disposed between the main body and an annular ring body that surrounds the main body. The term “main body” is not to be construed in a limiting way, although this may be the largest component of the lubricating device. The main body can be made of a single piece, or it may comprise a plurality of elements that are rigidly connected. The inner portion may extend at least partially circumferentially around the dispenser wall. It is at least partially disposed between the dispenser wall and the main body. The outer portion is disposed between the main body and the ring body. Like the main body, the ring body can be made of a single piece or of several pieces. The ring body is annular in shape and surrounds the main body. The outer portion may extend at least partially circumferentially around the main body, in particular it may be annular so that it extends fully around the main body. The inner portion and the outer portion are connected, e.g., by at least one connecting channel. The overall structure with the main body and the ring body may be comparable to a banjo fitting.

[0018] Preferably, the lubricating device comprises a main cavity extending from the inlet opening to the outlet opening and being defined by a cavity wall, the separator body is disposed inside the main cavity, and a sealing wall extends from the separator body to the cavity wall, so that an unfiltered portion of the gas duct is at least partially defined by the cavity wall, the sealing wall and the filter wall, and the lubricant cavity is at least partially disposed inside the main cavity and is partially defined by the sealing wall. The sealing wall may serve as fixing and sealing member. It may be formed as an annular ring that can be fixed to the separator body by any appropriate technique, e.g. press fitting, sintering,welding or caulking. The main cavity may be fully or at least partially cylindrical. It extends from the inlet opening to the outlet opening. The cavity wall that defines the main cavity may in particular be part of the abovementioned main body. The separator body is disposed inside the main cavity and may at partially be in contact with the cavity wall and / or spaced therefrom. As a rule, it is at least indirectly in contact with the cavity wall. A sealing wall extends from the separator body to the cavity wall, i.e., it is interposed between the separator body and the cavity wall. More specifically, it may sealingly engage the separator body and the cavity wall. While the dispenser wall is somewhat permeable for the lubricant, the sealing wall is impermeable for the lubricant. Thus, it provides a seal that partially defines the lubricant cavity. Also, it protects a part of the main cavity from the lubricant, while another part of the main cavity is a part of the lubricant cavity. Specifically, an unfiltered portion of the gas duct is at least partially defined by the cavity wall, the sealing wall and the filter wall. In particular, the sealing wall may engage the separator body “between” the filter wall and the dispenser wall, i.e., it may engage the separator body in a transition portion between the two walls. The lubricant cavity is at least partially disposed inside the main cavity and is partially defined by the sealing wall. Of course, it is also partially defined by the dispenser wall.

[0019] Preferably, a filtered portion of the gas duct, which is disposed downstream of the filter wall and comprises the lubricating portion, is at least partially defined by the separator body and the cavity wall. The filtered portion is disposed downstream of the filter wall. Accordingly, the gas stream in this portion has undergone filtering. The filtered portion comprises the lubricating portion, but it may extend upstream and / or downstream beyond the lubricating portion. In this embodiment, the filtered portion can be partially defined by the filter wall and by the dispenser wall. In any case, it is also partially defined by the cavity wall. Particularly, it may be defined only by the separator body and the cavity wall.

[0020] The supply assembly may further comprise a lubricant doser at least indirectly connecting the lubricant cavity to a lubricant supply and adapted to control introduction of the lubricant into the lubricant cavity. The lubricant supply can be a reservoir like a tank or a pump that is connected to such a reservoir. The lubricant doser comprises a valve that can at least be opened or closed in order to allow or prevent lubricant flow. Preferably, the lubricant doser is controlled electrically. It is connected to each of the lubricant supply and lubricant cavity either directly or indirectly, e.g., via a lubricant pipe.

[0021] According to one embodiment, the lubricant doser is disposed adjacent to the lubricant cavity and is connected to the lubricant supply via at least one lubricant pipe. In case of a plurality of lubricating devices, one “dedicated” lubricant doser can be disposedadjacent to the lubricant cavity of each lubricating device, and all lubricant dosers can be connected via at least one lubricant pipe to a single lubricant supply. The respective lubricant pipe is adapted to contain and convey lubricant. It normally has a length that it considerably greater than the maximum dimension of its cross-section (e.g., its diameter). The lubricant pipe can be linear or branching. It can be straight, curved and / or angled. In this embodiment, it connects the lubricant supply to the lubricant doser, which is disposed remotely from the lubricant supply. The lubricant doser is disposed adjacent to the lubricant cavity and may even partially define the lubricant cavity. For instance, the lubricant doser can be rigidly connected to a body that at least partially defines the lubricant cavity, e.g., to the abovementioned main body.

[0022] The supply assembly may comprise at least one fuel injector adapted to receive at least a part of the gas stream and to inject the gasesous fuel into the engine. The gas duct may at least be a part of the fuel injector, or it may be disposed upstream of the injector, so that the fuel injector receives gas from the gas duct. Either way, the injector is adapted to inject the gas into the engine. This may in particular refer to a direct injection of the gas, so that the fuel injector is adapted for direct injection of the gas into a combustion chamber of a cylinder of the respective engine. However, the fuel injector could also be configured for indirect injection. Fuel injectors for hydrogen-containing fuel are known in the art and the details of the fuel injector are not important in the context of this embodiment. The fuel injector may extend along an injector axis from a proximal side to a distal side, which faces the engine. The general flow direction of the gas is from the proximal side to the distal side. It may comprise an injector body defining a gas passage, which gas passage extends through the injector body and communicates with an outlet opening, which is disposed on the distal side of the injector body. As a rule, the outlet opening can be closed by a pintle that cooperates with a valve seat. It will be understood that the supply assembly may comprise a plurality of injectors, corresponding to a plurality of injectors for a single cylinder of the engine and / or a plurality of cylinders.

[0023] Preferably, at least one fuel injector has an injector housing to which a lubricating device is at least partially mounted. In this embodiment, the lubricating device and the fuel injector can be regarded as a unit and the lubricating device may at least partially be integrated into the injector. The injector housing, which may comprise one or several elements, may form a part of the lubricating device, while other parts of the lubricating device are mounted to the injector housing. It is also possible that the lubricating device is mounted at the proximal side of the injector body. The gas duct may be directly connected to the gas passage of the injector. In other embodiments, the gas duct and the gas passagemay at least partially be identical. The lubricating device may be mounted so that it is at least partially symmetrical to the injector axis. As mentioned above, it may comprise the main body and the ring body that circumferentially surrounds the main body. In this case, the main body can be mounted to the injector housing. The ring body can be connected to a lubricant pipe or directly to a lubricant doser.

[0024] In particular, each of a plurality of fuel injectors can be connected to a fuel rail. In this case, one embodiment provides that each of a plurality of lubricating devices is disposed at least adjacent to one of the fuel injectors, and a lubricant doser is connected to the lubricant cavity of each lubricating device via at least one lubricant pipe. In other words, a single lubricant doser is used to supply lubricant to the lubricating devices of each fuel injector. Each lubricating device is associated with one fuel injector, and vice versa. The lubricating device is either disposed adjacent to the respective fuel injector, or it may be fully or partially be integrated into the fuel injector. One could say that this embodiment combines a “centralized” lubricant doser with a plurality of “decentralized” lubricating devices. The lubricant doser can be connected to all lubricating devices via a single lubricant pipe, wherein the lubricating devices are arranged in series. Alternatively, it may be connected by a plurality of lubricant pipes, wherein the lubricating devices are arranged in parallel. Of course, there are also a variety of mixed arrangements that combine parallel and serial connections. The at least one lubricant pipe can comprise a dedicated body that is separate from the fuel rail. Alternatively, the lubricant pipe may be formed by an additional bore in the fuel rail.

[0025] According to another embodiment, at least one fuel injector is disposed remotely from a lubricating device and is connected thereto via a gas line. In case of a plurality of fuel injectors, the gas line may at least partially be identical to a fuel rail. In other words, a plurality of injectors may be disposed remotely from a lubricating device and be connected thereto via a fuel rail. This concept corresponds to a centralized lubrication.BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Preferred embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings, in which:Fig.1 is a sectional view of a first embodiment of an inventive supply assembly;Fig.2 is a schematic view of the supply assembly from fig.1 and an engine;Fig.3 is a sectional view of a second embodiment of an inventive supply assembly;Fig.4 is a detail view of fig.2;Fig.5 is a sectional view of a third embodiment of an inventive supply assembly;Fig.6 is a sectional view of a fourth embodiment of an inventive supply assembly; andFig.7 is a perspective view of the separation body used in the embodiment of Figs. 3 and 4.DETAILED DESCRIPTION OF THE EMBODIMENTS

[0027] Fig. 1 shows a sectional view of a first embodiment of an inventive supply assembly 1 for a hydrogen internal combustion engine 50, while fig. 2 is a schematic diagram of the supply assembly 1 and the engine 50. A central element of the supply assembly 1 is a lubricating device 10, which can be seen in detail in fig. 1. The lubricating device 10 comprises a main body 11 , which can be made of a single piece of metal or several connected pieces. The main body 11 defines a main cavity 12 that extends along a flow axis A from an inlet opening 16, on an upstream side, to an outlet opening 17, on a downstream side. A separator body 20 is disposed inside the main cavity 12. The shape of the separator body 20 is overall cylindrical and symmetric to the flow axis A. The side surface of the cylinder, which is parallel to the flow axis A, consists of a dispenser wall 21 on a downstream side and a part of a filter wall 22. Another part of the filter wall 22 is formed by the upstream base 8 of the cylinder. The downstream base 9 of the cylinder is open. The dispenser wall 21 comprises several thousands of dispenser apertures. These are through- openings in the dispenser wall 21 , each of which has a maximum dimension between 5 and 20 pm measured parallel to the dispenser wall 21. The filter wall 22, on the other hand, comprises several thousands of filter apertures. These are through-openings having a maximum dimension between 2 and 10 pm measured parallel to the filter wall 22.

[0028] At its downstream side, the separator body 20 is in direct contact with a cavity wall 13 of the main cavity 12. In a region between the filter wall 22 and the dispenser wall 21 , a sealing wall 25 sealingly engages the separator body 20 and the cavity wall 13. Beside this, the separator body 20 is held in position via a spring element 19 that is prestressed by a fitting 18 that is screwed into the main cavity 12. Radially outside of the dispenser wall 21 , the lubricating device 10 defines a lubricant cavity 27. Specifically, the lubricant cavity is defined by the cavity wall 13, the dispenser wall 21 and the sealing wall 25. Those parts ofthe main cavity 12 that do not belong to the lubricant cavity 27 are part of a gas duct 15 which is adapted for guiding a gas stream F from the inlet opening 16 to the outlet opening 17. Those parts of the gas duct 15 that are upstream from the filter wall 22 form an unfiltered portion 15.1 , while those parts downstream of the filter wall 22 form a filtered portion 15.2. Within this filtered portion 15.2, a lubricating portion 15.3 can be identified radially inside of the dispenser wall 21.

[0029] In the embodiment of Fig.1 , but also in the other embodiments, the separator body 20 comprises straight tubular sections that form the (upstream) filter wall 22 and the (downstream) dispenser wall 21. The wall thickness of the tubular sections may be adapted in either section depending on the filtering, respectively dispensing effect, to be achieved. For example, the wall thickness of the tubular sections may between 0.25 and 1.0 mm. The upstream end of the separator body 20 is closed by the end wall 8. This end wall 8 may be a nonporous wall, although in these embodiments it has a similar porosity as the filter wall. Hence the hydrogen stream is forced to enter the separator body 20 through the lateral filter wall 22 and end wall 8 - since it cannot flow around the separator body 20 nor through the sealing wall 25. At the opposite end, the separator body 20 has an open end 9.

[0030] The sealing wall 25 may serve as sealing and fixing member. Sealing wall 25 may typically be an annular ring that can be fixed to the separator body by any appropriate technique, e.g. by press fitting, welding, sintering or caulking. Depending on the application, sealing wall 25 can be made from metal or plastic material.

[0031] The separator body 20 can be manufactured by any appropriate technology. It is preferably a metallic element (e.g. stainless steel) of tubular shape with walls having holes / pores that allows flow through the wall thickness of the separator body. The two sections (filter 22 and dispenser 21) of separator body 20 preferably have different porosities (although not required). For example, a separator body can be manufactured by winding a continuous porous metal ribbon onto a cylindrical mandrel. The winding process is carried out to control the winding angle and to make a seamless wound element. The wound element is then sintered to ensure total integration of metal to metal at the crossing points. Fig.7 illustrates a separation body 20 manufactured from wound porous ribbons exhibiting two sections with different porosity, the filter section and dispenser section. The wound structure is closed upstream of the filter section by crimping or sintering the end of the tube. This is the separation body 20 installed in the injector in Figs. 3-4.

[0032] A lubricant doser 30 is disposed adjacent to the lubricant cavity 27. It comprises a doser housing 31 that is connected to the main body 11 by means not depicted here (e.g., by screws). The lubricant doser 30 is connected to a lubricant pipe 4 via a lubricant channel14 defined within the main body 11. As can be seen in fig. 2, the lubricant pipe 4 is connected to a lubricant tank 2 via a pump 3. The lubricant doser 30 comprises a check valve 32 that faces the lubricant cavity 27. The check valve 32 can be actuated by a magnetic force generated by a solenoid. By opening the check valve 32, liquid lubricant L can be injected into the lubricant cavity 27. The lubricant doser 30 is configured to introduce small amounts / drops of oil, e.g. about 2 mm3per shot / injection.

[0033] As can be seen in fig. 2, the lubricating device 10, or rather the gas duct 15, is integrated into a gas line 6 which connects a gas tank 5 to a fuel injector 40 of the engine 50. When the injector 40 is open and injects gas into the engine 50, the gas stream F runs through the gas duct 15, which has two effects. On the one hand, as the gas stream F passes through the filter wall 22, contaminant particles are held back by the filter wall 22, while the gas components (and possibly smaller, less relevant particles) can pass through the filter apertures. Accordingly, a largely “clean” gas stream F enters the filtered portion 15.2. Also, as the gas stream F flows through the lubricating portion 15.3, it passes the dispenser wall 21 with a nonzero velocity, thereby creating a pressure difference. The size of the dispenser apertures is selected so that surface tension prevents the lubricant L from passing therethrough into the lubricating portion 15.3 as long as there is no gas stream F or no significant velocity of the gas stream. Although not willing to be bound by theory, it is believed that when the velocity of the gas stream F creates a significant reduction in static pressure within the lubricating portion 15.3, the pressure difference overcomes the forces of the surface tension and small droplets of lubricant L exit the dispenser apertures and enter into the gaseous gas stream F. Anyway, a sucking effect is created that causes oil to be sucked into the interior of the tubular dispenser section, and carried with the gaseous fuel. This effect is enhanced by the fact that the dispenser wall 21 is disposed circumferentially around the lubricating portion 15.3, wherein droplets basically from the entire area of the dispenser wall 21 and from multiple directions. Accordingly, a mist of lubricant droplets is carried away with the gas stream F and helps to lubricate any components downstream of the lubricating portion 15.3. This pertains in particular to the fuel injector 40 and the engine 50.

[0034] While in the embodiment shown in figs. 1 and 2, the lubricating device 10 is disposed remotely from the fuel injector 40, figs. 3 and 4 show a different embodiment in which the lubricating device 10 is directly connected to an injector housing 41 of the fuel injector 40. The fuel injector 40 is not depicted in detail here, since its general design and components will be in to those skilled in the art. It comprises a gas passage 42 that extends along aninjector axis B to an outlet opening 43. In this embodiment, the main body 11 of the lubricating device 10 is directly connected to the injector housing 41 by screwing.

[0035] The main cavity 12 defined by the main body 11 is symmetric to a flow axis A, which in this embodiment is identical to the injector axis B. Although the shape and relative dimensions of the separator body 20, the dispenser wall 21 , the filter wall 22, the sealing wall 25 and the gas duct 15 differ somewhat from the first embodiment, their functions and general arrangement is the same and therefore will not be explained again. In this embodiment, the lubricant cavity 27 comprises an inner portion 27.1 that is disposed between the main body 11 and the dispenser wall 21 , and an outer portion 27.2 that is defined between the main body 11 and an annular ring body 23 that is overall annular in shape and is disposed circumferentially around the main body 11. The ring body 23 is secured on the main body 11 by a nut 26, while two O-rings 24 provide a fluid-tight seal between the ring body 23 and the main body 11. The inner portion 20.1 and the outer portion 27.2 are connected by a plurality of connecting channels 27.3 which traverse the cavity wall 13 of the main body 11 . The outer portion 27.2 is connected to a lubricant pipe 4 via a check valve 28. The lubricant pipe 4, in turn, is connected to a lubricant doser 30 (similar to the one shown in fig. 1) that is disposed remotely from the lubricating device 10.

[0036] Figs. 5 and 6 show simplified views of supply assemblies 1 which may use the configuration shown in fig. 4. In case of fig. 5, a plurality of gas injectors 40, each with a lubricating device 10, are connected to a rail portion 6.1 of a gas line 6 via dedicated connecting portions 6.2 that branch off the rail portion 6.1. In a similar way, each lubricating device 10 is connected to a main portion 4.1 of a lubricant pipe 4 via branch portions 4.2. Again, the lubricant pipe 4 is connected to a remotely disposed lubricant doser 30 (not shown). In this embodiment, one could say that the lubricating devices 10 are connected “in parallel”. The main portion 4.1 of the lubricant pipe for is integrated into a rail body 7 of the rail portion 6.1 as an additional bore.

[0037] The embodiment shown in fig. 6 is similar to fig. 5. However, in this case, the lubricant devices 10 are connected “in series” by a linear, unbranched lubricant pipe 4. This lubricant pipe 4 is separate from the rail body 7.Legend of Reference Numbers:1 supply assembly2 lubricant tank3 tank4 lubricant pipe4.1 main portion4.2 branch portion5 gas tank6 gas pipe6.1 rail portion6.2 connecing portion7 rail body10 lubricating device11 main body12 main cavity13 cavity wall14 lubricant channel15 gas duct15.1 unfiltered portion15.2 filtered portion15.3 lubricating portion16 inlet opening17 outlet opening18 fitting19 spring element20 separator body21 dispenser wall22 filter wall23 ring body24 o-ring25 sealing wall26 nut27 lubricant cavity1 inner portion 2 outer portion 3 connecting channel8 check valve 0 lubricant doser 1 doser housing 2 check valve 0 fuel injector 1 injector housing2 gas passage 3 outlet opening 0 engineA flow axisB injector axisF gas streamL lubricant

Claims

CLAIMS1. A supply assembly (1) for an internal combustion engine (50) powered with gaseous fuel, the supply assembly (1) comprising a lubricating device (10) with a gas duct (15) for conveying a gas stream (F), preferably containing hydrogen gas, from an inlet opening (16) to an outlet opening (17), a lubricant cavity (27) that is adapted to contain liquid lubricant (L), and a separator body (20) with a porous dispenser wall (21) comprising a plurality of dispenser apertures, the dispenser wall (21) partially defining the lubricant cavity (27) and being interposed between the lubricant cavity (27) and a lubricating portion (15.3) of the gas duct (15), wherein the gas duct (15) is adapted to convey the gas stream (F) at least partially through the lubricating portion (15.3) along the dispenser wall (21), and the dispenser wall (21) is adapted to release lubricant (L) through the dispenser apertures into the lubricating portion (15.3) in response to an underpressure in the lubricating portion (15.3) with respect to the lubricant cavity (27); the supply assembly further comprising a porous filter wall (22) for removing contaminant particles from the gas stream (F), the filter wall (22) comprising a plurality of filter apertures and being disposed in the gas duct (15) upstream of the lubricating portion (15.3); the dispenser wall (21) and the filter wall (22) being connected as parts of the separator body (20).

2. The supply assembly according to claim 1 , wherein at least a majority of the dispenser apertures has a size between 2 and 30 pm, preferably between 5 and 20 pm.

3. The supply assembly according to any of the preceding claims, wherein at least a majority of the filter apertures has a size between 1 and 15 pm, preferably between 2 and 10 pm.

4. The supply assembly according to any of the preceding claims, wherein the dispenser wall (21) extends at least partially circumferentially around a flow axis (A) that traverses the lubricating portion (15.3), and at least a portion of the lubricant cavity (27) extends at least partially circumferentially around the dispenser wall (21).

5. The supply assembly according to any of the preceding claims, wherein the lubricant cavity (27) comprises an inner portion (27.1) that is disposed within a main body (11)and is disposed adjacent to the dispenser wall (21), and an outer portion (27.2) that is disposed between the main body (11) and an annular ring body (23) that surrounds the main body (11).

6. The supply assembly according to any of the preceding claims, wherein the lubricating device (10) comprises a main cavity (12) extending from the inlet opening (16) to the outlet opening (17) and being defined by a cavity wall (13), the separator body (20) is disposed inside the main cavity (12), and a sealing wall (25) extends from the separator body (20) to the cavity wall (13), so that an unfiltered portion (15.1) of the gas duct (15) is at least partially defined by the cavity wall (13), the sealing wall (25) and the filter wall (22), and the lubricant cavity (27) is at least partially disposed inside the main cavity (12) and is partially defined by the sealing wall (25).

7. The supply assembly according to any of the preceding claims, wherein a filtered portion (15.2) of the gas duct (15), which is disposed downstream of the filter wall (22) and comprises the lubricating portion (15.3), is at least partially defined by the separator body (20) and the cavity wall (13).

8. The supply assembly according to any of the preceding claims, further comprising a lubricant doser (30) at least indirectly connecting the lubricant cavity (27) to a lubricant supply (2) and adapted to control introduction of the lubricant (L) into the lubricant cavity (27).

9. The supply assembly according to claim 8, wherein the lubricant doser (30) is disposed adjacent to the lubricant cavity (27) and is connected to the lubricant supply (2) via at least one lubricant pipe (4).

10. The supply assembly according to any of the preceding claims, comprising at least one fuel injector (40) adapted to receive at least a part of the gas stream (F) and to inject gas into the engine (50).

11. The supply assembly according to any of the preceding claims, wherein at least one fuel injector (40) has an injector housing (41) to which a lubricating device (10) is at least partially mounted.

12. The supply assembly according to any of the preceding claims, wherein each of a plurality of fuel injectors (40) is connected to a fuel rail (6.1), each of a plurality oflubricating devices (10) is disposed at least adjacent to one of the fuel injectors (40), and a lubricant doser (30) is connected to the lubricant cavity (27) of each lubricating device (10) via at least one lubricant pipe (4).

13. The supply assembly according to any of the preceding claims, wherein at least one fuel injector (40) is disposed remotely from a lubricating device (10) and is connected thereto via a gas line (6).

14. The supply assembly according to any of the preceding claims, wherein the gaseous fuel is hydrogen.

15. A internal combustion engine powered with gaseous fuel, in particular hydrogen, comprising a supply assembly according to any one of the preceding claims.

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