Fuel injector for direct injection of gaseous fuel
By using a high thermal conductivity heat dissipation ring in the fuel injector combined with a shroud design, the problem of the sealing ring losing its sealing function in high temperature environments is solved, achieving higher sealing ring temperature control and engine performance improvement.
Patent Information
- Application Number
- CN202380045869.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2022-06-09
- Filing Date
- 2023-05-17
- Publication Date
- 2025-01-21
AI Technical Summary
The sealing rings of existing fuel injectors are prone to lose their sealing function in high temperature environments, resulting in gas fuel leakage and engine performance degradation.
A fuel injection is designed, which is combined with a combination of heat dissipation ring and a diversion cover. The heat dissipation ring is made of a second metal with a high heating rate. It is located on the far side of the sealing ring. The temperature of the seal ring.
Effectively protect the sealing ring, avoid losing the sealing function caused by overheating, and improve the reliability of the fuel injection and the combustion quality of the engine.
Smart Images
Figure CN119343512A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a fuel injector for direct injection of gaseous fuel. The present invention also relates to an engine assembly. Background Art
[0002] For automotive applications, hydrogen engines are considered a promising alternative to gasoline or diesel engines because their emissions consist primarily of water. However, using hydrogen as a fuel in an internal combustion engine presents several challenges, some of which stem from the combustion characteristics of hydrogen. Compared to other fuel types, hydrogen has a higher laminar flame speed, a lower flameout distance, a larger flammable range, and a higher flame temperature. These characteristics increase the heat input to the fuel injectors mounted to the cylinder head of the engine.
[0003] For example, an outwardly opening fuel injector may be used, i.e. a fuel injector having a pivot that opens toward the combustion chamber of the cylinder. In order to improve the combustion quality of the engine, it is beneficial to introduce the airflow into the combustion chamber in a controlled manner. To this end, the fuel injector may be equipped with a deflector facing the combustion chamber at its end. Due to its position, the deflector is directly exposed to the heat inside the combustion chamber, which increases the heat flow into the injector. Although most components of the fuel injector may be made of materials like stainless steel (which are resistant to high temperatures), this is not the case for every component. For example, it is known to use a sealing ring on a fuel injector, which is inserted between the injector body and the cylinder head and provides an airtight seal between the combustion chamber and the surrounding environment of the engine. Such a sealing ring is usually made of a PTFE polymer filled with carbon to improve thermal conductivity. The recommended maximum operating temperature of such a ring is 260°C. Exceeding this limit, it may begin to lose its sealing function.
[0004] Technical issues
[0005] It is therefore an object of the present invention to provide a device for protecting a sealing ring of a fuel injector from overheating.
[0006] This problem is solved by a fuel injector according to claim 1 and an engine assembly according to claim 14 . Summary of the invention
[0007] The present invention provides a fuel injector for directly injecting a gaseous fuel. In other words, the fuel injector is designed for an engine suitable for gaseous fuel. "Gaseous fuel" generally refers to a fuel that is gaseous under standard conditions (i.e., 15°C and 101325Pa). Specifically, the gaseous fuel may be hydrogen (H2). The fuel injector is suitable for injecting the gaseous fuel directly into a combustion chamber of a cylinder of a corresponding engine. However, this does not exclude the possibility that the fuel injector can be used for indirect injection.
[0008] The fuel injector extends from a proximal side to a distal side along an axial direction. The axial direction may correspond to an injector axis, which may be an axis of symmetry of at least some components of the fuel injector. When the fuel injector is mounted to the engine, the proximal side is the side facing away from the engine, and the distal side faces the engine. The general flow direction of the fuel is from the proximal side to the distal side.
[0009] The fuel injector comprises an injector body, which defines a fuel passage and has an end portion arranged at the distal side, which end portion is made of a first metal and defines a valve seat extending around an outlet opening, at least the end portion being adapted to be inserted into an axial through hole of a cylinder head. The fuel passage extends through the injector body and is communicated with the outlet opening arranged at the distal side of the injector body. The end portion of the injector body at the distal side defines a valve seat extending around the outlet opening. The end portion is made of a first metal, which is usually stainless steel. Other parts of the injector body or the entire injector body may be made of the first metal. The term "first metal" explicitly includes alloys, which may also include at least one semi-metal, semiconductor and / or non-metal. Typically, the valve seat and the outlet opening are symmetrical relative to the above-mentioned symmetry axis of the fuel injector. In addition, the fuel passage may be symmetrical relative to the axis. At least the end portion of the injector body is adapted to be inserted into a through hole of a cylinder head. The outlet opening of the fuel injector is arranged near the interior of the cylinder head, i.e. near the combustion chamber. The through hole axially passes through the wall of the cylinder head. The end portion is adapted to the size of the through hole so that it can be inserted from the outside of the cylinder head. Strictly speaking, in a state in which the fuel injector is mounted on the engine, the through hole is axially aligned with at least the end portion inserted into the through hole.
[0010] The fuel injector further comprises an outwardly opening pivot which is accommodated in the injector body so as to be axially movable between a proximal closed position in which it engages with the valve seat to close the outlet opening and a distal open position in which it opens the outlet opening. The pivot is usually accommodated in the injector body so that it can slide along the axial direction. It can be biased towards the closed position by a spring element while it can be moved towards the open position by an electromagnetic actuator. Various operating principles for moving the pivot of a fuel injector are known in the art, all of which are possible in the context of the present invention. The term "outwardly opening" means that when the fuel passage is open, the pivot moves outwardly relative to the fuel passage, i.e. towards the cylinder. In the closed position, the pivot engages with the above-mentioned valve seat (in an airtight manner) to prevent fuel from leaving the fuel passage. In the open position, it disengages from the valve seat, thereby opening the fuel passage via the outlet opening. Typically, the pivot is also made of stainless steel.
[0011] The fuel injector also includes a sealing ring, which surrounds the end portion in the first axial region and is suitable for sealingly engaging the inner surface of the through hole. The sealing ring is arranged circumferentially around the end portion. The function of the sealing ring is to prevent any gas exchange between the inside and the outside of the engine (cylinder) via the through hole. Therefore, it should provide an airtight seal between the end portion and the inner surface of the through hole. The sealing ring has an annular shape and surrounds the end portion in the tangential direction. It is usually made of polymer material. In particular, it can be made of PTFE filled with carbon, which is intended to enhance the thermal conductivity of the sealing ring. When the end portion is inserted into the through hole, the sealing ring engages with the inner surface of the through hole and the end portion, thereby providing a seal between the injector body and the cylinder head. Relative to the axial direction, the sealing ring is arranged in the first axial region. The first axial region can also be referred to as the first gap along the axial direction.
[0012] In addition, the fuel injector comprises a shroud connected to the end portion and extending distally beyond the end portion and defining at least one outlet hole in communication with the outlet opening. The term "shroud" should not be interpreted in any way to limit the shape of the shroud. Typically, at least the portion of the shroud connected to the end portion has an annular shape. The shroud extends further to the distal side than the end portion, or it can be said that it protrudes distally relative to the end portion. Therefore, it is closer to the cylinder than the end portion, or may even be arranged inside the cylinder. It comprises at least one outlet hole in communication with the outlet opening. Therefore, gaseous fuel leaving the outlet opening can leave the fuel injector through the outlet hole. Due to its position, the shroud is usually the part of the fuel injector exposed to the highest temperature. Typically, it is also made of stainless steel. When the fuel injector is mounted to the engine, the shroud can be in contact with the inner surface of the through hole, thereby facilitating heat transfer from the shroud to the cylinder head. This heat transfer can protect the end portion and possible other components of the fuel injector from excessive temperatures. The deflector can be accommodated above the recessed portion of the end portion. The recessed portion is radially recessed, i.e. it is radially set back relative to the adjacent protruding portion. Therefore, the deflector is partially arranged outside the end portion relative to the radial direction. The radially outer surface of the deflector can be provided with the same cross-sectional profile as the adjacent protruding portion.
[0013] Furthermore, the fuel injector comprises a heat sink ring which is arranged in a second axial region which is offset distally from the first axial region and which at least mostly tangentially surrounds the end portion, the heat sink ring being adapted to be in thermal contact with the end portion and the inner surface when the end portion is inserted into the through hole. The function of the heat sink ring is to provide a heat flow from the end portion to the cylinder head which bypasses the sealing ring. Typically, the sealing ring is sensitive to high temperatures. For example, a sealing ring made of PTFE can typically only withstand temperatures up to 260° C. Since the heat sink ring is arranged in a second axial region which is offset distally from the first axial region, any heat flow from the shroud at the distal side reaches the heat sink ring before it reaches the sealing ring. Since the heat sink ring is in thermal contact with the end portion and the inner surface, at least a large part of the heat flow can be transferred to the cylinder head before it reaches the sealing ring. The second axial region is offset distally from the first axial region, which includes the possibility of these regions overlapping with respect to the axial direction. However, even in this case, a portion of the sealing ring is arranged on the proximal side of the entire heat dissipation ring, and a portion of the heat dissipation ring is arranged on the distal side of the entire sealing ring. The heat dissipation ring completely (i.e. 360°) or mostly (usually more than 300° or 330°) tangentially surrounds the end portion. In the latter case, it is not a ring in the strict sense, but for simplicity, the term "ring" is used here and below. In addition to its heat dissipation function, the heat dissipation ring can also provide a seal between the end portion and the inner surface, thereby supplementing the function of the sealing ring. However, at least in some embodiments, the sealing function of the heat dissipation ring is incomplete and / or inferior to that of the sealing ring.
[0014] The heat sink ring is made of a second metal having a thermal conductivity that is at least 50% higher than the thermal conductivity of the first metal. This generally excludes the possibility that the heat sink ring can be made of stainless steel or any iron-based alloy. Preferably, the thermal conductivity of the second metal is at least two times, at least three times or at least four times higher than the thermal conductivity of the first metal. It is understood that the increased thermal conductivity greatly supports the function of the heat sink ring. As a result, the heat flow through the heat sink ring towards the cylinder head is significantly increased. The term "second metal" explicitly includes alloys, which may also include at least one semi-metal, semiconductor and / or non-metal.
[0015] Preferably, the second metal comprises copper. That is, it can be copper or a copper alloy. Such copper-containing metals have high thermal conductivity and are relatively cheap compared to metals like silver or gold. Preferably, the second metal comprising copper has a thermal conductivity of at least 100 W / mK. At the same time, at least some of copper and its alloys are relatively soft in the annealed state, so that the heat sink ring is unlikely to damage the inner surface of the through hole. Soft copper (annealed) or soft copper alloys are considered particularly practical. The cylinder head is typically made of cast aluminum alloys (e.g., AlSi8Cu3 or AlSi6Cu4) or cast iron. Generally, the second metal as used in the heat sink ring preferably has a hardness lower than the hardness of the cylinder head to avoid damage. This is typically the case with soft copper / copper alloys.
[0016] Preferably, the heat sink ring is designed to be press-fitted into the through hole under deformation so that it presses against the inner surface. On the one hand, the heat sink ring is sized so that it contacts the inner surface, but on the other hand, it also allows for a certain degree of elastic and / or plastic deformation so that it can be installed in the through hole. In this embodiment, it is useful if the second metal has a much lower hardness than the material of the cylinder head. For example, as mentioned above, the cylinder head can be made of steel and the second material can include copper.
[0017] Preferably, the sealing ring and the heat dissipation ring are arranged on at least one recessed portion of the end portion, wherein the heat dissipation ring is at least partially arranged to the distal side of the sealing ring. The at least one recessed portion is radially inwardly retreated relative to at least one adjacent protruding portion. The two parts may define a step between them. Since the corresponding ring is arranged in the recessed portion, it is prevented from axially moving to the adjacent protruding portion by forming a lock. The protruding portion may exist on either side of the recessed portion, in which case the groove defined by the recessed portion may also be referred to as a "groove portion". Regardless of the configuration of at least one recessed portion and the ring, the heat dissipation ring is at least partially arranged on the distal side of the sealing ring. This includes the possibility that there may be some overlap between the two rings. However, the heat flow from the deflector on the distal side of the fuel injector reaches the heat dissipation ring before it reaches the sealing ring. Therefore, at least a large part of the heat flow can be transferred to the cylinder head through the heat dissipation ring.
[0018] One embodiment provides that the sealing ring and the heat dissipation ring are arranged in the same recess. They can be in contact with each other, but it is also conceivable that they are axially spaced apart from each other. In the latter case, the recess can have a structure that provides a forced locking / form-fit locking in the axial direction, thereby preventing the sealing ring and the heat dissipation ring from moving axially. Since the recess of this embodiment usually defines a groove, during assembly, each of the rings must be expanded to move into the recess. For the sealing ring, this is usually not a problem, because it is usually made of an easily deformable material and can therefore be easily expanded and compressed. On the other hand, the heat dissipation ring usually requires a special configuration to facilitate radial expansion and / or compression. In this regard, some options will be discussed below.
[0019] Alternatively, the sealing ring may be arranged on a first recessed portion, and the heat sink ring is arranged on a second recessed portion axially spaced from the first recessed portion by a ridge portion radially protruding relative to the recessed portion. The second recessed portion may also define a groove, in which case the second recessed portion has radial protrusions on each side. However, the second recessed portion may also extend to the distal end of the end portion. This greatly facilitates the assembly of the heat sink ring to the end portion, because it can be moved into place from the distal side of the end portion without any significant radial expansion. In addition, the deflector can be accommodated around the second recessed portion. The presence of the ridge portion separating the first recessed portion and the second recessed portion also helps to protect the sealing ring from high temperatures, because there is no direct thermal contact between the heat sink ring and the sealing ring. Ideally, at least most of the heat is dissipated into the cylinder head through the heat sink ring before it reaches the sealing ring. Optionally, heat can also flow from the ridge portion to the heat sink ring, thereby protecting the ridge portion from reaching a temperature that may be harmful to the sealing ring arranged in the adjacent first recessed portion.
[0020] According to one embodiment, the heat dissipation ring is circumferentially closed along the tangential direction. Alternatively, the heat dissipation ring may include a narrow slot extending axially and radially. The narrow slot may be straight and may be aligned along the axial direction. However, it may be aligned at a certain angle to the axial direction. It may also have a non-linear shape, such as a wavy or meandering shape. In short, the narrow slot facilitates the deformation of the heat dissipation ring, which helps to press fit it into the through hole. In addition, it can be used to mount the heat dissipation ring on the end portion, for example, when it must be arranged on the recessed portion and needs to expand to move past the adjacent protruding portion.
[0021] Alternatively or additionally, the heat dissipation ring may have a corrugated profile along the tangential direction in an undeformed state. In other words, as shown in the radial tangential plane, the profile of the heat dissipation ring is not a simple circular ring, which can be described by a single inner diameter and outer diameter. Instead, the profile undulates along the tangential direction, i.e. it alternately protrudes and recedes. Typically, alternatively or additionally, the corrugations are located in the radial direction, but may also be located in the axial direction. It will be understood that the corrugated structure allows the heat dissipation ring to deform, thereby achieving expansion and compression, respectively.
[0022] According to one embodiment, the heat dissipation ring is a laminated ring that forms a labyrinth seal relative to the axial direction. This laminated ring is referred to in the art as a sealing element. The laminated ring is not closed in the tangential direction, but includes at least one element that is spirally wound around the axial direction and overlaps with itself. Typically, each element is made of a metal strip with an oblate cross-section that is larger in the radial direction than in the axial direction. Several such elements can be arranged adjacent to each other or axially spaced apart from each other along the axial direction. Each element can be regarded as a heat dissipation ring, or the entire group of elements can be regarded as a single heat dissipation ring. The open structure of each element facilitates radial deformation, which is beneficial during the assembly of the heat dissipation ring to the end portion and / or during the insertion of the end portion and the heat dissipation ring into the through hole.
[0023] One embodiment provides that the heat sink ring is wound helically around the tangential direction. In other words, the general shape of the heat sink ring is a spiral, wherein the axis of the spiral is not straight but annular and extends along the tangential direction. This spiral shape allows for deformation in the axial direction and in the radial direction, thereby facilitating press-fitting the heat sink ring into the through hole.
[0024] To facilitate assembly, the air deflector and the end portion can be releasably connected, for example by forced locking / form-fit locking or by friction locking. Such a connection can allow for the air deflector to be deformed independently of the end portion, for example, when the fuel injector is press-fitted into the through hole. Another preferred embodiment provides that the air deflector is materially bonded to the end portion. In particular, it can be welded to the end portion. The end portion and the air deflector are usually made of stainless steel, so that a connection by welding can be easily established. The material bonding between the air deflector and the end portion provides a safe connection without any risk of misalignment, for example when the fuel injector is inserted into the through hole. Although this connection promotes heat transfer from the air deflector to the end portion, this effect is mitigated or eliminated by the presence of the heat dissipation ring, which dissipates heat from the end portion towards the cylinder head.
[0025] In the assembled state, the deflector can, for example, extend to the distal end of the through hole so that it is flush with the inner surface of the combustion chamber. Even so, the deflector will still be exposed to extremely high temperatures. However, the deflector is usually designed to extend distally beyond the through hole and into the combustion chamber. In this case, the degree of exposure to high temperatures is even higher. However, this configuration can allow for improved fuel injection, because the at least one outlet hole can be arranged inside the combustion chamber. For example, it can be pointed at a certain angle relative to the axial direction, so that "tilted" injection can be achieved.
[0026] It is usually desirable that the air guide cover is in contact with the heat sink ring. However, in practice, the overpressure in the combustion chamber may push the heat sink ring toward the proximal side, thereby away from the air guide cover. Therefore, the heat sink ring is usually spaced apart from the air guide cover so that it is in indirect thermal contact with the air guide cover only via the end portion.
[0027] In some embodiments, the shroud may be formed as a tubular or sleeve-shaped structure extending from the end portion toward the distal side. In such an embodiment, the outer diameter and inner diameter of the shroud may remain constant along the axial direction, or they may only show slight variations. Depending on the inner diameter of the shroud, the shroud defines a single relatively large outlet hole at its distal end. This configuration provides only limited protection for the end portion and the pivot, as they may be significantly exposed to the temperature of the combustion chamber. According to another embodiment, the shroud includes an annular connecting portion connected to the end portion and a shield portion spaced apart from the end portion and extending radially inward from the connecting portion. The shield portion may extend radially inward to form a shield or dome, which is closed except for the at least one outlet hole typically arranged in the shield portion. These outlet holes may be configured to guide the exiting fuel (or fuel-air mixture), which may be different from that achieved by the outlet opening alone. The shield portion may be provided with a plurality of outlet holes, and the positions of these outlet holes may be selected to achieve a predetermined injection form. The shield portion forms a shield extending perpendicularly to the axial direction, thereby preventing direct impact of hot gases and infrared radiation on the end portion and the distal end of the pivot. A cavity or chamber may be formed between the shield portion and the end portion and / or the pivot. Such a chamber may promote mixing of air and fuel.
[0028] The present invention also relates to an engine assembly. The engine assembly is a part of an engine, or includes the entire engine. Specifically, it is an engine assembly for an engine for gaseous fuel. In some embodiments, the engine assembly may also be referred to as an injector assembly or a cylinder head assembly. It includes a cylinder head with an axial through hole and a fuel injector for directly injecting gaseous fuel. The fuel injector extends from a proximal side to a distal side along an axial direction, and includes:
[0029] an injector body defining a fuel passage and having a distally arranged end portion made of a first metal and defining a valve seat extending around the outlet opening, the end portion being at least adapted to be inserted into the through hole;
[0030] an outwardly opening pivot, the pivot being received in the injector body so as to be axially movable between a proximal closed position in which the pivot engages the valve seat to close the outlet opening and a distal open position in which the pivot opens the outlet opening;
[0031] - a sealing ring surrounding the end portion in a first axial region and sealingly engaging an inner surface of the through hole;
[0032] a flow deflector connected to the end portion and extending distally beyond the end portion and defining at least one outlet aperture communicating with the outlet opening,
[0033] a heat sink ring arranged in a second axial region distally deviating from the first axial region and at least mostly tangentially surrounding the end portion, the heat sink ring being in thermal contact with the end portion and the inner surface, wherein the heat sink ring is made of a second metal having a thermal conductivity at least 50% higher than the thermal conductivity of the first metal.
[0034] All these terms have been explained above with respect to the fuel injector of the present invention, and thus will not be explained again.Preferred embodiments of the engine assembly of the present invention correspond to the embodiments of the fuel injector of the present invention.
[0035] Generally, the fuel injector may be part of a fuel delivery system, which includes: a pressurized gas tank containing pressurized gaseous fuel (e.g., hydrogen); and a fuel rail connected to the gas tank via a supply line, to which the fuel injector is also connected. The fuel delivery system may also include at least one of a pressure regulator, a shutoff valve, a purge valve, and a pressure relief valve; and the latter may be arranged in the same or different housings. BRIEF DESCRIPTION OF THE DRAWINGS
[0036] Preferred embodiments of the present invention will now be described by way of example with reference to the accompanying drawings, in which:
[0037] Figure 1 is a cross-sectional view of an engine assembly having a first embodiment of a fuel injector of the present invention in a closed position;
[0038] Figure 2 Has fuel injectors Figure 1 A cross-sectional view of an engine assembly in an open position;
[0039] Figure 3 is a cross-sectional view of an engine assembly having a second embodiment of a fuel injector of the present invention; and
[0040] Figures 4 to 8 An embodiment of a heat sink ring for a fuel injector of the present invention is shown. DETAILED DESCRIPTION
[0041] Figure 1 and Figure 2An engine assembly 1 according to the invention is shown. The engine assembly 1 comprises a cylinder head 2 covering a combustion chamber 5 of an engine cylinder. The engine is adapted for use with a gaseous fuel F, in this case hydrogen. A through hole 3 (or a bore) passes through the wall of the cylinder head 2 in an axial direction A, which implicitly defines a radial direction and a tangential direction. The cylindrical through hole 3 is delimited by an inner surface 4 of the cylinder head 3. The engine assembly 1 further comprises a fuel injector 10, of which only its distal end closest to the combustion chamber 5 is shown. The fuel injector 10 comprises an injector body 11 made of stainless steel. At least an end portion 12 of the injector body 11 is inserted into the through hole 3. The injector body 11 defines a fuel channel 13, which extends axially and is connected to an outlet opening 14. A pivot 15 is movably accommodated inside the injector body 11. At Figure 1 1 , the outlet opening 14 is closed by a pivot head 15.2 protruding radially from the pivot rod 15.1. Specifically, the pivot head 15.2 rests on a valve seat 12.1 formed by the end portion 12 around the outlet opening 14. The pivot 15 is also made of stainless steel. The pivot 15 is biased into the closed position by a spring element (not shown). It is moved to the open position by an electromagnetic actuator, for example, a solenoid type actuator (also not shown).
[0042] Although not shown in the drawings, the injector body 11 comprises an upper portion having an inlet for gaseous fuel from which gas F can flow through the body internally towards the opposite end portion 12 and the valve seat 12.1. Typically, the injector gaseous fuel inlet is connected to a fuel rail which in turn is connected by a supply line to a fuel tank containing pressurized fuel gas (e.g. hydrogen).
[0043] The outer dimensions of the end portion 12 are not constant along the axial direction A. Instead, it comprises a first protruding portion 12.2, a first recessed portion 12.3, a second protruding portion or ridge portion 12.4 and a second recessed portion 12.5 extending up to the distal end of the end portion 12. The first recessed portion 12.3 forms a groove between adjacent protruding portions 12.2, 12.4 in which a sealing ring 16 is accommodated. The sealing ring 16 is made of a PTFE polymer filled with carbon and extends over a first axial region A1 relative to the axial direction A. It sealingly engages the end portion 12 and the inner surface 4, thereby providing a gas-tight seal between the combustion chamber 5 and the exterior of the cylinder head 2.
[0044] The air deflector 17 is accommodated around the second recessed portion 12.5 and is connected to the end portion 12 by a weld 21. Specifically, the connecting portion 17.1 of the air deflector 17 is welded to the end portion 12. While the connecting portion 17.1 is generally cylindrical and extends generally parallel to the axial direction A, the shield portion 17.2 extends radially inwardly from the connecting portion 17.1 and forms a generally dome-shaped shape. A plurality of outlet holes 18 are arranged in the shield portion 17.2 and communicate with the outlet opening 14 via a cavity 19 formed in the air deflector 17.
[0045] When the pivot 15 moves to Figure 2 In the open position shown in , the deflector 17 with its outlet hole 18 helps to shape and guide the flow of gaseous fuel F. In addition, the cavity 19 may be beneficial for mixing the gaseous fuel F with air, and it may protect the end portion 12 and the pivot 15 from excessive heat exposure. However, since the deflector 17 with the shield portion 17.2 extends distally beyond the through hole 3 and into the combustion chamber 5, it is subject to high temperatures (which are particularly high due to the combustion of hydrogen). Since the deflector 17 is in thermal contact with the inner surface 4, some of the heat may be dissipated into the cylinder head 2 before it flows into the end portion 12. However, a considerable heat flow from the deflector 17 to the end portion 12 cannot be prevented. This will pose a potential risk of damage to the sealing ring 16, which can only withstand a temperature of 260°C before it begins to deteriorate.
[0046] To alleviate this problem, the fuel injector 10 also includes a heat dissipation ring 20, which is arranged on the second recessed portion 12.5 and close to the air shroud 17. Specifically, the heat dissipation ring 20 is arranged in the second axial region A2 spaced apart from the first axial region A1 distally. When the fuel injector 10 is assembled to the cylinder head 2, the heat dissipation ring 20 is press-fit into the through hole 3 so that it is in thermal contact with the end portion 12 and the inner surface 4 of the cylinder head 2. It should be understood that during the assembly process of the fuel injector 10, the heat dissipation ring 20 can pass through the second recessed portion 12.5 before the air shroud 17 is placed on the second recessed portion 12.5 and welded to the second recessed portion. The shape of the heat dissipation ring 20 can be as follows: Figure 4 , i.e., a closed annular shape. As described above, although the end portion 12 is made of stainless steel, the single heat dissipation ring 20 is made of copper or a copper alloy. Therefore, its thermal conductivity is at least four times that of the end portion 12. Therefore, a considerable portion of the heat flow is transferred to the cylinder head 2 through the heat dissipation ring 20 before it reaches the sealing ring 16. The hardness of the heat dissipation ring 20 is significantly lower than that of the cylinder head 2, so when the heat dissipation ring 20 is press-fitted into the through hole 3, the cylinder head 2 is not damaged.
[0047] Figure 3A second embodiment of the engine assembly 1 of the present invention is shown, which is substantially the same as the first embodiment and will not be discussed further. However, in this case, the first recessed portion 12.3 also extends to the distal side and accommodates a sealing ring 16 as well as a heat dissipation ring 20. The two rings 16, 20 are arranged adjacent to each other. Therefore, the second axial area A2 is adjacent to the first axial area A1 on the distal side. Although in the first embodiment, the heat dissipation ring 20 can be pushed through the end portion 12 in the axial direction, in the second embodiment, this is not possible due to the presence of the second protrusion or ridge portion 12.4. Therefore, the heat dissipation ring 20 needs to be radially expanded so that it can move past the ridge portion 12.4. To this end, as shown Figure 5 As shown in FIG, the heat dissipation ring 20 may include a slot 20.1.
[0048] Although Figure 4 and Figure 5 The ring 20 shown in FIG. 1 has a circular cross section perpendicular to the axial direction A, but Figure 6 An embodiment is shown in which the heat dissipation ring 20 has a corrugated profile along the tangential direction. This shape also allows the heat dissipation ring 20 to expand radially. Figure 7 An embodiment is shown in which the heat dissipation ring 20 is a laminated ring which acts as a labyrinth seal with respect to the axial direction A. Figure 8 This is an embodiment in which the heat dissipation ring 20 has a spiral structure (indicated by a dotted line) wound around a tangential direction.
[0049] Legend to the accompanying drawings:
[0050] 1 Engine components
[0051] 2 Cylinder head
[0052] 3 Through holes
[0053] 4 Inner surface
[0054] 5 Combustion Chamber
[0055] 10 Fuel Injectors
[0056] 11 Fuel injector body
[0057] 12 End section
[0058] 12.1 Valve seat
[0059] 12.2, 12.4 Protruding parts
[0060] 12.3, 12.5 Recessed part
[0061] 13 Fuel Channel
[0062] 14 Exit opening
[0063] 15 Pivot
[0064] 15.1 Pivot rod
[0065] 15.2 Pivot head
[0066] 16 Sealing ring
[0067] 17. Air deflector
[0068] 17.1 Connection
[0069] 17.2 Protective cover
[0070] 18 Exit hole
[0071] 19 Cavity
[0072] 20 Heat sink
[0073] 20.1 Slots
[0074] 21 Weld
[0075] A Axial direction
[0076] A1, A2 axial area
[0077] F Fuel
Claims
1. A fuel injector (10) for directly injecting a gaseous fuel (F), the fuel injector extending from a proximal side to a distal side along an axial direction (A) and comprising: - an injector body (11) defining a fuel passage (13) and having a distally arranged end portion (12), the end portion being made of a first metal and defining a valve seat (12.1) extending around an outlet opening (14), at least the end portion (12) being adapted to be inserted into an axial through hole (3) of a cylinder head (2); - an outwardly opening pivot (15) housed in the injector body (11) so as to be axially movable between a proximal closed position, in which the pivot engages with the valve seat (12.1) to close the outlet opening (14), and a distal open position, in which the pivot opens the outlet opening (14); - a sealing ring (16) surrounding the end portion (12) in a first axial region (A1) and adapted to sealingly engage the inner surface (4) of the through hole (3); a flow deflector (17) connected to the end portion (12) and extending distally beyond the end portion (12) and defining at least one outlet hole (18) communicating with the outlet opening (14), a heat dissipation ring (20), which is arranged in a second axial region (A2) distally deviated from the first axial region (A1) and at least mostly tangentially surrounds the end portion (12), and when the end portion (12) is inserted into the through hole (3), the heat dissipation ring (20) is suitable for thermal contact with the end portion (12) and the inner surface (4), Wherein, the heat dissipation ring (20) is made of a second metal, and the second metal has a thermal conductivity at least 50% higher than that of the first metal.
2. The fuel injector according to claim 1, wherein: The second metal includes copper.
3. A fuel injector according to any one of the preceding claims, wherein: The heat dissipation ring (20) is designed to be press-fitted into the through hole (3) in a deformed state, so that the heat dissipation ring is pressed against the inner surface (4).
4. A fuel injector according to any one of the preceding claims, wherein: The sealing ring (16) and the heat dissipation ring (20) are arranged on at least one recessed portion (12.3, 12.5) of the end portion (12), wherein the heat dissipation ring (20) is at least partially arranged on the distal side of the sealing ring (16).
5. A fuel injector according to any one of the preceding claims, wherein: The sealing ring (16) and the heat dissipation ring (20) are arranged on the same recessed portion (12.3, 12.5).
6. A fuel injector according to any one of the preceding claims, wherein: The sealing ring (16) is arranged on the first recessed portion (12.3), and the heat dissipation ring (20) is arranged on the second recessed portion (12.5), which is axially spaced apart from the first recessed portion (12.3) by a ridge portion (12.4) protruding radially relative to the recessed portions (12.3, 12.5).
7. A fuel injector according to any one of the preceding claims, wherein: The heat dissipation ring (20) comprises slits (20.1) extending axially and radially.
8. A fuel injector according to any one of the preceding claims, wherein: The heat dissipation ring (20) has a corrugated profile along the tangent direction in an undeformed state.
9. A fuel injector according to any one of the preceding claims, wherein: The heat dissipation ring (20) is a laminated ring that forms a labyrinth seal with respect to the axial direction (A).
10. A fuel injector according to any one of the preceding claims, wherein: The heat dissipation ring (20) is spirally wound around the tangential direction.
11. A fuel injector according to any one of the preceding claims, wherein: The deflector (17) is materially bonded to the end portion (12).
12. A fuel injector according to any one of the preceding claims, wherein: The deflector (17) is designed to extend distally beyond the through hole (3) and into the combustion chamber (5).
13. A fuel injector according to any one of the preceding claims, wherein: The deflector (17) comprises an annular connecting portion (17.1) connected to the end portion (12) and a shield portion (17.2), the annular connecting portion being connected to the end portion (12), the shield portion being spaced apart from the end portion (12) and extending radially inward from the connecting portion (17.1).
14. An engine assembly (1) having a cylinder head (2), the engine assembly comprising an axial through hole (3) and a fuel injector (10) for directly injecting a gaseous fuel (F), the fuel injector (10) extending from a proximal side to a distal side along an axial direction (A) and comprising: - an injector body (11) defining a fuel channel (13) and having a distally arranged end portion (12), the end portion being made of a first metal and defining a valve seat (12.1) extending around an outlet opening (14), at least the end portion (12) being adapted to be inserted into the through hole (3); - an outwardly opening pivot (15) housed in the injector body (11) so as to be axially movable between a proximal closed position, in which the pivot engages with the valve seat (12.1) to close the outlet opening (14), and a distal open position, in which the pivot opens the outlet opening (14); a sealing ring (16) surrounding the end portion (12) in a first axial region (A1) and sealingly engaging an inner surface (4) of the through hole (3); a flow deflector (17) connected to the end portion (12) and extending distally beyond the end portion (12) and defining at least one outlet hole (18) communicating with the outlet opening (14), a heat dissipation ring (20), which is arranged in a second axial region (A2) distally deviated from the first axial region (A1) and at least mostly tangentially surrounds the end portion (12), the heat dissipation ring (20) being in thermal contact with the end portion (12) and the inner surface (4), Wherein, the heat dissipation ring (20) is made of a second metal, and the second metal has a thermal conductivity at least 50% higher than that of the first metal.