Injection valve for gaseous fuel

Abstract

In a gas fuel injection valve (10), a partition (33) divides the fuel passage into an upstream first fuel passage (P1) and a downstream second fuel passage (P2), and a communication hole (34) is provided in the partition to allow fluid communication between these passages. Inside the main body are a first valve (13) that opens and closes the communication hole from the side of the first fuel passage, a second valve (14) that opens and closes the communication hole from the side of the second fuel passage, and a sealing element (27) that seals around the opening of the communication hole between the first valve and the partition.The first valve is actuated to open by a drive unit (25), while the second valve opens when the pressure inside the communication hole exceeds the preload force of a preload element (45), which pushes the second valve towards the closed position. When the second valve opens, the gaseous fuel discharged from the communication hole undergoes adiabatic expansion and impinges on an extended section (35, 38) that extends downstream of the separation, thereby cooling the extended section.

Description

Cross-reference to related registration

[0001] This application is based on Japanese patent application JP 2023-127077 A, filed on August 3, 2023, the disclosure of which is incorporated herein by reference. Technical field

[0002] The disclosure in this specification relates to an injection valve for gaseous fuel. General state of the art

[0003] A gas metering valve, as disclosed, for example, in patent literature 1, is known as an injection valve for gaseous fuel used in direct-injection gas engines. In this gas metering valve, an elastomeric sealing element is provided on a valve element actuated by a control element to suppress the escape of gaseous fuel. Simultaneously, the sealing position of the valve element is arranged significantly away from a fuel outlet opening to prevent damage to the sealing element from the heat and pressure generated during combustion in a gas engine. Additionally, a check valve (passive type valve) is provided in the gas metering valve between the valve element actuated by a control element and the outlet opening, which opens in response to the pressure difference between the upstream and downstream sides.This configuration serves to suppress the propagation of flames or combustion pressure from the combustion chamber to the sealing element. This effectively protects the elastomeric sealing element. Literature on the state of the art, patent literature

[0004] Patent literature 1: JP 2023 - 513 065 A Summary of the invention

[0005] The technology described in patent literature 1, however, increases the distance between the valve element with the sealing element and the downstream check valve, resulting in a larger volume between these valve elements and the check valve. Therefore, it is conceivable that the closing response of the check valve when the upstream valve element closes is reduced due to the increased volume, and that, as a result of this reduced responsiveness, gas leaks may occur at the fuel injection valve, which in turn raises concerns about combustion anomalies in the gas engine. Conversely, if the upstream valve element with its sealing function is positioned closer to the check valve, there is a risk that the sealing element of the valve element will be damaged by heat.

[0006] The present invention was made taking into account the aforementioned circumstances, and one object of it is to provide an injection valve for gaseous fuel which can ensure the injection performance of the gaseous fuel and at the same time protect the sealing element.

[0007] According to the present disclosure, a gaseous fuel injector injects gaseous fuel directly into a combustion chamber of an internal combustion engine. The gaseous fuel injector comprises a main body in a cylindrical shape. The main body includes a fuel passage and an injection orifice. The fuel passage is located inside the main body, and the injection orifice is located at a pointed end of the main body. The main body has a partition or separating element that divides the fuel passage into a first fuel passage and a second fuel passage. The first fuel passage is an upstream section of the fuel passage. The second fuel passage is a downstream section of the fuel passage.The partition has a communication port through which the first fuel passage is connected to the second fuel passage. The main body includes a first valve, a second valve, and a sealing element within the main body. The first valve opens and closes the communication port from one side of the first fuel passage, and the second valve opens and closes the communication port from one side of the second fuel passage. A sealing element is located between the first valve and the partition and seals an area around one opening of the communication port. The first valve is opened by an actuator, and the second valve opens in response to a pressure within the communication port exceeding a preload force of a preload element, which pushes the second valve toward a closed position.The main body further comprises an extended section that stretches from the separation point towards the downstream section. The main body includes a structure that cools the extended section by causing the gaseous fuel, which has flowed out of the communication hole and undergone adiabatic expansion upon opening the second valve, to impinge upon the extended section.

[0008] In the fuel injector with the configuration described above, the upstream side of the divider in the cylindrical body section serves as the first fuel passage, and the downstream side of the divider serves as the second fuel passage, with the first and second fuel passages connected by the communication orifice. When the first valve is opened by the actuator and the communication orifice opens from the side of the first fuel passage, the pressure within the communication orifice increases due to the opening of the first valve, thereby opening the passive second valve and also opening the communication orifice on the side of the second fuel passage. When the communication orifice is open on both the upstream and downstream sides, gaseous fuel is injected from the fuel injector.In this case, a sealing element is provided between the first valve and the partition, which seals around the opening of the communication hole, thereby improving the gas sealing performance compared to a configuration where the first valve and the partition are in direct contact when the first valve is closed.

[0009] When gaseous fuel flows out of the communication hole upon opening of the second valve, it undergoes adiabatic expansion, and the separator is cooled by the gaseous fuel, whose temperature has decreased due to this expansion. That is, when the second valve opens, the gaseous fuel exiting the communication hole and undergoing adiabatic expansion encounters an extended section extending downwards from the separator, thus cooling this extended section. As the extended section cools, the separator is further cooled. Additionally, as the separator is cooled, the sealing element, which is located across the separator on the opposite side of the second valve (the side of the first valve), is also cooled.Although the sealing element is positioned relatively close to the second valve, separated only by the partition, excessive temperature rise of the sealing element is suppressed. Furthermore, because the upstream and downstream valves are located relatively close to the partition, with the partition situated between them, any decrease in the responsiveness of the passive second valve is prevented. This protects the sealing element while ensuring the injection performance of the gaseous fuel. Brief description of the illustrations

[0010] The foregoing and further tasks, features, and advantages of the present disclosure will become more apparent from the following detailed description with reference to the accompanying illustrations. The illustrations show: Fig. 1. A longitudinal section view of a fuel injector; Fig. 2 a perspective view of a second cylindrical section; Fig. 3 an enlarged longitudinal section view showing a nozzle body and a lower valve; Fig. 4 a sectional view along a line 4-4 in Fig. 3; Fig. 5 a perspective view of the lower valve; Fig. 6 a longitudinal section view showing the fuel injector in an open state; Fig. 7 an enlarged longitudinal sectional view showing the nozzle body and the lower valve in another embodiment; and Fig. Figure 8 shows a longitudinal section view showing the configuration of the fuel injector in another embodiment. Detailed description of embodiments

[0011] The following describes an embodiment that specifies a gaseous fuel injection valve according to the present disclosure with reference to the figures. The gaseous fuel injection valve according to the present embodiment is used in a direct-injection gas engine (internal combustion engine) that uses either hydrogen, CNG (compressed natural gas), or LNG (liquefied natural gas) as a gaseous fuel. The gaseous fuel is injected directly into a combustion chamber of the gas engine by the gaseous fuel injection valve. The gas engine is, for example, an in-vehicle engine.The fuel injection system according to the present embodiment is a so-called low-pressure direct injection system in which a gaseous fuel compressed to several MPa is injected from the fuel injection valve into the combustion chamber.

[0012] The structure of a fuel injector 10 is described using the following: Fig. 1 explained. In the following description, the direction along the axis extending longitudinally and passing through the center of the cross-section of the fuel injector 10 is referred to as the axial direction. The direction extending radially from the axis is referred to as the radial direction, and the direction extending circumferentially around the axis is referred to as the circumferential direction. Fig. 1 is the right side referred to as the base end side (upstream side) of the fuel injector 10, and the left side is referred to as the tip end side (downstream side).

[0013] The fuel injector 10 essentially comprises a housing 11, a nozzle body 12 located at the tip end of the housing 11, an upper valve 13, which is movably mounted within the housing 11, and a lower valve 14, which is movably mounted within the nozzle body 12. The upper valve 13 is an active upstream valve that opens by electromagnetic actuation, while the lower valve 14 is a passive downstream valve that opens in response to the pressure differential between the upstream and downstream sides. In the fuel injector 10, the opening of the upper valve 13 causes the lower valve 14 to open, and when both valves 13 and 14 are open, the gaseous fuel is injected from the injection orifice 15.It should be noted that the housing 11 and the nozzle body 12 correspond to the “main body”, the upper valve 13 corresponds to the “first valve”, and the lower valve 14 corresponds to the “second valve”.

[0014] Although not shown, as it is a known structure, the fuel injector 10 is mounted on the gas engine such that its tip (the nozzle body 12) is exposed within the combustion chamber. The fuel injector 10 injects gaseous fuel directly into the combustion chamber. The construction of the individual parts of the fuel injector 10 is explained in detail below.

[0015] The housing 11 is cylindrical, and a fixed core 21 is secured within a hollow section thereof. Additionally, the upper valve 13 is mounted in a position aligned axially with the fixed core 21, allowing it to move back and forth. The upper valve 13 includes a movable core. The fixed core 21 is cylindrical, and a first spring 22, a compression coil spring, is located within the fixed core 21. The first spring 22 is positioned between a spring seat section 21a of the fixed core 21 and the axial end surface of the upper valve 13. By means of the first spring 22, the upper valve 13 is biased toward the tip end face of the fuel injector 10 (i.e., in a direction to close the communication hole 34 from the base end face, as will be described later).

[0016] The fixed core 21 has a hollow section 21b, and the upper valve 13 has a hollow section 13a. These hollow sections 21b and 13a extend axially and are interconnected. When gaseous fuel is supplied from the fuel line provided at the base end face with respect to the fixed core 21, the gaseous fuel is introduced to the tip end face of the upper valve 13 via an upstream fuel passage P1 formed by the hollow sections 21b and 13a of the fixed core 21 and the upper valve 13, respectively. In the present embodiment, for example, hydrogen gas is used as the gaseous fuel, and gaseous fuel compressed to approximately 3 MPa is introduced into the fuel passage P1.

[0017] Furthermore, a coil 25 is provided in the housing 11 as a drive unit for the fuel injection valve 10. A line signal is supplied to the coil 25 from a power supply device (not shown) via a wiring harness 26. When the coil 25 is energized, magnetic energy is generated, and this magnetic energy causes the upper valve 13 to be moved towards the open position against the preload force of the first spring 22.

[0018] The nozzle body 12 is provided on the downstream side of the upper valve 13. The nozzle body 12 has a first cylinder 31 at the tip end and a second cylinder 32 at the base end, the inner circumferential sides of these cylinders 31 and 32 forming a downstream fuel passage P2. An injection hole 15 is formed at one end in the axial direction of the first cylinder 31. The second cylinder 32 has an end plate 33, which is provided at the base end of the second cylinder 32. The end plate 33 is provided with communication holes 34, which extend in the axial direction. The end plate 33 serves as a separator or separating element which separates the upstream fuel passage P1, formed by the fixed core 21 and the upper valve 13, from the downstream fuel passage P2, formed by the nozzle body 12, in the fuel injector 10.The communication port 34 is a connecting passage that links the upstream and downstream fuel passages P1 and P2. The end plate 33 acts as a pressure barrier to prevent the pressure generated by combustion in the combustion chamber of the machine from propagating to the upstream fuel passage P1.

[0019] Fig. Figure 2 is a perspective view of the second cylinder, 32. As in Fig. As shown in Figure 2, the second cylinder 32 is provided with a circumferential wall 35 that extends downwards (to the left in the figure) from the outer circumferential section of the end plate 33. Additionally, communication holes 34 are provided on the end plate 33 in a circumferential arrangement along the circumferential wall 35. Each communication hole 34 is formed in an arc extending in the circumferential direction. However, the opening shape of each communication hole 34 can be arbitrary and, for example, have a circular opening shape.

[0020] Returning to the description of Fig. 1 is an annular, plate-shaped sealing element 27 fixed to the axial end surface of the upper valve 13 at a position facing the opening of each communication hole 34. In the state in which the upper valve 13 is closed by the preload force of the first spring 22 (which is shown in Fig. (as shown in Figure 1), the sealing element 27 comes into contact with the seat surface 33a, which corresponds to the axial end surface of the end plate 33, and the first opening, which corresponds to the upstream opening of the communication hole 34, is closed by the sealing element 27. When the upper valve 13 is then moved into the open position, the sealing element 27 disengages from the seat surface 33a of the end plate 33, and the first opening is opened. The sealing element 27 is made of any elastic material that exhibits elasticity, such as a rubber material, a resin material, or an elastomer material, and in particular, fluororubber or EPDM (ethylene propylene diene monomer rubber) is preferably used as the sealing material.

[0021] Within the nozzle body 12, the lower valve 14 is provided for opening and closing the communication port 34 from the fuel passage P2 side. The lower valve 14 comprises a cylindrical section 41 and a flange-shaped opening / closing section 42, which extends radially and is provided at an axial end of the cylindrical section 41. The cylindrical section 41 is a sliding section that can slide axially along the inner circumferential surface of the first cylinder 31, and the opening / closing section 42 is a sealing plate that closes the second opening, corresponding to the downstream opening of the communication port 34. The opening / closing section 42 can be raised between a closed position, in which it blocks the second (downstream) opening of the communication port 34, and an open position, in which the second opening is open.In the present embodiment, the opening / closing section 42 has an annular plate shape and is provided such that it extends radially outwards from the cylindrical section 41.

[0022] A second spring 45, a compression coil spring, is arranged between the opening / closing section 42 and the axial end surface of the first cylinder 31. The second spring 45 biases the lower valve 14 towards the base end of the fuel injector 10 (i.e., in a direction that closes the communication hole 34 from the tip end). The lower valve 14 opens when the pressure inside the communication hole 34 exceeds the bias force of the second spring 45. The second spring 45 acts as a "biasing element".

[0023] The lower valve 14 can be made of a metal, a non-metal, or another non-elastomeric material with excellent heat resistance. Pressing the opening / closing section 42 against the downstream opening of the communication hole 34 suppresses the escape of gaseous fuel from the communication hole 34 and simultaneously also suppresses the entry of flames or combustion pressure from the combustion chamber.

[0024] In the end plate 33, the communication hole 34 is closed by the upper valve 13 from the side of the fuel passage P1, corresponding to one side in the axial direction, and also by the lower valve 14 from the side of the fuel passage P2, corresponding to the other side in the axial direction. The upper valve 13 is an inwardly opening valve that opens towards the base end of the fuel injector 10, while the lower valve 14 is an outwardly opening valve that opens towards the tip end of the fuel injector 10.

[0025] When the upper valve 13 in the fuel injector 10 is moved to the open position by energizing the coil 25, the gaseous fuel flows in the upstream fuel passage P1 into the communication port 34, causing a pressure increase within the communication port 34. When the pressure in the communication port 34 then exceeds the preload force of the second spring 45, the lower valve 14 is moved to the open position. If, in this case, both the upper and lower valves 13 and 14 on both sides of the communication port 34 are in the open position, gaseous fuel flows from the upstream fuel passage P1 to the downstream fuel passage P2, and gaseous fuel is also injected from the injection port 15 at the tip of the fuel passage P2.

[0026] In the fuel injection valve 10 according to the present embodiment, gaseous fuel remains in the communication hole 34 provided on the end plate 33 during a period between the closing and subsequent opening of the upper valve 13. In this case, the total volume of the communication holes 34 provided in the end plate 33 corresponds to the residual gas volume that remains on the downstream side of the upper valve 13 during the period between the closing and subsequent opening of the upper valve 13.

[0027] The following describes in detail the configuration in connection with the outflow of gaseous fuel from the communication hole 34 when the lower valve 14 is opened. Fig. Figure 3 is an enlarged longitudinal section view showing the nozzle body 12 and the lower valve 14, and Fig. Figure 4 is a sectional view along line 4-4 in Fig. 3. In Fig. 4 is the communication hole 34 of the end plate 33, represented by a dashed line. Fig. Figure 5 is a perspective view of the lower valve 14.

[0028] As in Fig. As shown in Figure 3, a sliding surface 36 is formed in the nozzle body 12 to allow the cylindrical section 41 of the lower valve 14 to slide on the inner circumferential section of the first cylinder 31. Additionally, an enlarged inner circumferential surface 37 is formed on the inner circumferential sections of the first cylinder 31 and the second cylinder 32, which has a larger diameter than the sliding surface 36. Consequently, the inner circumferential side of the circumferential wall 35 forms an enlarged space S1, which is radially extended outwards in the most upstream section (i.e., in a predetermined area on the most upstream side) of the fuel passage P2.This means that in the nozzle body 12, the passage diameter of the fuel passage P2 differs between the upstream section and the downstream side thereof, and by increasing the passage diameter at the upstream section, an annular enlarged space S1 is formed. With respect to the lower valve 14, the enlarged space S1 is formed on the radially outer side of the cylindrical section 41.

[0029] The second spring 45 is accommodated within the enlarged space S1. It should be noted that the enlarged inner circumferential surface 37 and the enlarged space S1 formed by the enlarged inner circumferential surface 37 can be formed by either the first cylinder 31 or the second cylinder 32, or exclusively by the second cylinder 32, as long as these are located downstream of the end plate 33 in the nozzle body 12.

[0030] Furthermore, a downstream projecting projection 38 is provided at a central position on the downstream end surface of the end plate 33. The projection 38 is provided on the radially inner side of the circumferential wall 35, and in particular, the projection 38 is provided on the radially inner side of the cylindrical section 41 of the lower valve 14, which is located on the radially inner side of the circumferential wall 35. The projection 38 is conical in shape. However, the shape of the projection 38 is not limited to this and can be cylindrical, prismatic, pyramidal, or any other shape, and several projections 38 may also be provided. It should be noted that the circumferential wall 35 and the projection 38 correspond to the "extended section".

[0031] Here, as in Fig. Figure 4 shows that if the outer diameter of the cylindrical section 41 of the lower valve 14 (in other words, the inner diameter of the sliding surface 36 of the first cylinder 31) is defined as D1, the inner diameter of the enlarged inner circumferential surface 37 is defined as D2, and the outer diameter of the opening / closing section 42 of the lower valve 14 is defined as D3, these dimensions then exhibit the relationship D1 < D3 and D2 > D3. That is, the enlarged space S1 is formed by increasing the inner diameter D2 of the enlarged inner circumferential surface 37 with respect to the outer diameter D1 of the cylindrical section 41 (the inner diameter of the sliding surface 36). Furthermore, it is possible to form a radial gap between the enlarged inner circumferential surface 37 and the outer circumference of the opening / closing section 42, since the inner diameter D2 of the enlarged inner circumferential surface 37 is larger than the outer diameter D3 of the opening / closing section 42.

[0032] When the lower valve 14 is moved into the open position, the gaseous fuel exiting downstream from the communication hole 34 flows along both the radially outer and radially inner sides of the gap between the downstream end face of the end plate 33 and the opening / closing section 42. That is, the opening / closing section 42 has a section projecting radially outward from the opening of the communication hole 34 and a section projecting radially inward, and these projecting sections guide the gaseous fuel exiting the communication hole 34 in both the radially outward and radially inward directions. The opening / closing section 42 corresponds to a "guide section".At this time, the gaseous fuel, flowing radially outward, collides with the enlarged inner circumferential surface 37 (the inner circumferential surface of the circumferential wall 35) and is introduced into the enlarged space S1 through the gap between the enlarged inner circumferential surface 37 and the outer circumferential section of the opening / closing section 42. Additionally, the gaseous fuel, flowing radially inward, collides with the projection 38 of the end plate 33.

[0033] In addition, several openings 43 are provided at predetermined intervals in the circumferential direction on the cylindrical section 41 of the lower valve 14 (see Fig. 5) Therefore, the interior and exterior of the cylindrical section 41, i.e., the expanded space S1 and the inner space located radially inside it, are configured such that they are connected to each other via the opening 43.

[0034] Fig. Figure 6 is an illustration to explain the flow of gaseous fuel when the fuel injector 10 is in an open state. Fig. 6 both the upper valve 13 and the lower valve 14 of the fuel injector 10 are in the open state, and the flow of gaseous fuel is shown by arrows.

[0035] When the opening / closing section 42 moves away from the downstream end surface (downstream seat surface) of the end plate 33 upon opening of the lower valve 14, the gaseous fuel flows out of the communication hole 34, and at this time the temperature of the gaseous fuel decreases due to adiabatic expansion. Specifically, in a gas engine, gaseous fuel is injected from the fuel injector 10 during the intake stroke and / or the compression stroke. At the time of fuel injection, the pressure of the gaseous fuel is reduced from several MPa to approximately atmospheric pressure as the lower valve 14 opens and the gaseous fuel flows out of the communication hole 34. For example, the gas temperature is considered to decrease by 100 °C or more due to adiabatic expansion when the gas supply pressure is 2 MPa or higher.

[0036] The gaseous fuel exiting the communication hole 34 encounters the flange-shaped opening / closing section 42 and then flows downwards, splitting into a radially outer and a radially inner side. That is, the gaseous fuel exiting the communication hole 34 is guided by the opening / closing section 42 of the lower valve 14 to both the radially outer and the radially inner sides. The gaseous fuel directed to the radially outer side encounters the inner circumferential surface of the circumferential wall 35 and then flows downwards through the expanded space S1 and the opening 43 of the lower valve 14 into the fuel passage P2.Since the gaseous fuel, which has undergone a temperature decrease upon exiting the communication hole 34 due to adiabatic expansion, is introduced into the expanded space S1 at this time, heat exchange within the expanded space S1 is enhanced. Consequently, cooling of the end plate 33 is promoted and the temperature rise of the sealing element 27 is suppressed. In particular, immediately after exiting the communication hole 34, the gaseous fuel is initially directed towards the radially outer side, and then its flow direction changes towards the radially inner side, causing its path to meander or snake in the radial direction. This improves heat exchange with the second cylinder 32.

[0037] Furthermore, a second spring 45 is provided in the expanded space S1, and this second spring 45 is cooled by the gaseous fuel, the temperature of which has decreased due to adiabatic expansion. This makes it possible to reduce the thermal stress on the second spring 45, which is exposed to the flame in the engine's combustion chamber.

[0038] Furthermore, after the lower valve 14 opens, the gaseous fuel directed towards the radially inner side strikes the projection 38 in the center of the end plate 33. This cools the end plate 33 through the gaseous fuel, which has undergone adiabatic expansion, thereby suppressing the temperature rise of the sealing element 27.

[0039] According to the embodiment described in detail above, the following advantageous effects can be obtained.

[0040] In the fuel injector 10, a sealing element 27 is provided between the upper valve 13 and the end plate 33, so that a seal is provided around the opening of the communication hole 34. Consequently, compared to a configuration in which the upper valve 13 and the end plate 33 are in direct contact with each other when the upper valve 13 is closed, the gas sealing performance can be improved.

[0041] When the gaseous fuel exits the communication hole 34 upon opening of the lower valve 14, an adiabatic expansion of the gaseous fuel occurs, and the end plate 33 is cooled by the gaseous fuel, the temperature of which has decreased due to this adiabatic expansion. As the end plate 33 is cooled, the sealing element 27, which is located on the side of the end plate 33 opposite the lower valve 14 (i.e., on the side of the upper valve 13), is also cooled. Although in this case the sealing element 27 is located in a relatively close position to the lower valve 14, with only the end plate 33 between them, an excessive temperature rise of the sealing element 27 is suppressed.Furthermore, since the upper and lower valves 13 and 14 are positioned relatively close to each other, and the end plate 33 is located between them, a decrease in the response of the passive lower valve 14 is suppressed. This protects the sealing element 27 while simultaneously ensuring the injection performance of the gaseous fuel.

[0042] The communication hole 34 is located between the circumferential wall 35 and the projection 38 in the end plate 33 of the second cylinder 32. The opening / closing section 42 of the lower valve 14 directs the gaseous fuel, which has exited the communication hole 34 and undergone adiabatic expansion, to both the radially outer and radially inner sides, causing it to impact the circumferential wall 35 and the projection 38, respectively. In this case, the second cylinder section 32 is cooled when the gaseous fuel, whose temperature has decreased due to adiabatic expansion, impacts the circumferential wall 35 and the projection 38. This promotes the cooling of the end plate 33 and suppresses the temperature rise of the sealing element 27.

[0043] According to the configuration of the present embodiment, the desired cooling effect can be achieved by optimizing the flow direction of the cooling gas (the gaseous fuel after adiabatic expansion) using the lower valve 14. Thus, the sealing element 27 can be adequately cooled even with a simple structure.

[0044] In the fuel passage P2, the annular expanded space S1 is formed upstream within the nozzle body 12 by enlarging the passage dimensions, and the opening / closing section 42 of the lower valve 14 is configured such that it directs the gaseous fuel exiting the communication hole 34 towards the expanded space S1. Since, in this case, the gaseous fuel, which has been cooled by adiabatic expansion during the opening of the lower valve 14, is introduced into the expanded space S1, heat exchange within the expanded space S1 is improved. This promotes the cooling of the end plate 33 and suppresses the temperature rise of the sealing element 27.

[0045] The cylindrical section 41 of the lower valve 14 is provided with the opening 43, which connects the expanded space S1 with the inner space located radially inside it. In this case, the gaseous fuel, which has been cooled by adiabatic expansion during the opening of the lower valve 14, flows along a path where it is first introduced into the expanded space S1 and then passes through the opening 43 of the cylindrical section 41 into the inner space. Consequently, the gaseous fuel can be caused to meander or snake radially within the fuel passage P2, thereby improving heat exchange with the second cylinder 32.

[0046] The enlarged chamber S1 is equipped with a second spring 45, which biases the lower valve 14 towards the closed position. In this case, the second spring 45 is cooled by the gaseous fuel, the temperature of which has decreased due to adiabatic expansion. Consequently, the thermal stress on the second spring 45, which is exposed to the flame in the engine's combustion chamber, can be reduced.

[0047] The total volume of the multiple communication holes 34 provided in the end plate 33 of the second cylinder 32 is configured to represent the residual gas volume remaining on the downstream side of the upper valve 13 during the period between its closing and subsequent opening. That is, the end plate 33 only needs to separate the upstream and downstream fuel passages P1 and P2 and must have a plate thickness sufficient to withstand pressure waves from the engine's combustion chamber. The volume of the communication hole 34 corresponding to this plate thickness is the residual gas volume on the downstream side of the upper valve 13.In this case, unlike conventional structures where a spring or the like is arranged between the upper valve 13 and the lower valve 14, it is possible to reduce the residual gas volume and thereby improve the response performance or response behavior of the fuel injector 10. (Other embodiments)

[0048] The above embodiment can be modified, for example, as follows.

[0049] In the foregoing embodiment, the circumferential wall 35 and the projection 38 of the nozzle body 12 serve as the target (extended section) with which the gaseous fuel collides after adiabatic expansion. However, this configuration can be modified. For example, only the circumferential wall 35 can serve as the target (extended section) against which the gaseous fuel collides after adiabatic expansion. In particular, as shown in Fig. As shown in Figure 7, the opening / closing section 42 of the lower valve 14 has a disc shape without a central opening, and the projection 38 of the end plate 33 is omitted. In this case, the opening / closing section 42 of the lower valve 14 guides the gaseous fuel, which has exited the communication hole 34 and undergone adiabatic expansion, radially outwards, causing a collision of the gaseous fuel with the circumferential wall 35. Consequently, the end plate 33 is cooled along with the circumferential wall 35, thus suppressing the temperature rise of the sealing element 27.

[0050] The fuel injector 10 can also be used as in Fig. 8 shown, configured. Note that in Fig. 8 the main body section is designed as a cylindrical body and the end plate 33 (separation) is fixed at an intermediate position of the main body section. Fig. Figure 8 shows a state in which both the upper valve 13 and the lower valve 14 are in the open position.

[0051] In Fig.In the center of the disc-shaped end plate 33, a communication hole 34 is provided, and this communication hole 34 is opened and closed from the upstream side by the upper valve 13 and from the downstream side by the lower valve 14. The lower valve 14 is biased in one direction by the second spring 45 to close the downstream opening of the communication hole 34. In this configuration as well, the lower valve 14, as above, guides the gaseous fuel that has exited the communication hole 34 and undergone adiabatic expansion radially outward, so that the end plate 33, together with the circumferential wall 35, is cooled by the collision of the gaseous fuel with the circumferential wall 35, thereby suppressing the temperature rise of the sealing element 27. It should be noted that in the lower valve 14, the surface facing the end plate 33 corresponds to the "guide section".

[0052] In the foregoing embodiment, the sealing element 27 is provided between the upper valve 13 and the end plate 33, and the sealing element 27 is fixed to the axial end face of the upper valve 13; however, this arrangement can be modified. For example, the sealing element 27 can be fixed to the side of the end plate 33.

[0053] A configuration can be used as the drive unit for driving the upper valve 13 in which a motor is used instead of the coil 25.

[0054] The technical concept extracted from the foregoing embodiment is described below. (Initial configuration)

[0055] A gaseous fuel injector (10) injects gaseous fuel directly into a combustion chamber of an internal combustion engine. The gaseous fuel injector comprises a main body (11, 12) which is cylindrical in shape. The main body includes a fuel passage and an injection orifice (15). The fuel passage is located inside the main body, and the injection orifice is located at a pointed end of the main body. The main body has a partition (33) that divides the fuel passage into a first fuel passage (P1) and a second fuel passage (P2). The first fuel passage corresponds to an upstream section of the fuel passage. The second fuel passage corresponds to a downstream section of the fuel passage.The partition has a communication hole (34) through which the first fuel passage is connected to the second fuel passage. The main body includes a first valve (13), a second valve (14), and a sealing element (27) inside the main body. The first valve opens and closes the communication hole from one side of the first fuel passage, and the second valve opens and closes the communication hole from one side of the second fuel passage. A sealing element is located between the first valve and the partition and seals an area around one opening of the communication hole. The first valve is opened by an actuating unit (25), and the second valve opens in response to a pressure within the communication hole exceeding a preload force of a preload element (45), which pushes the second valve toward a closed position.The main body further comprises an extended section (35, 38) which extends from the separation point towards the downstream section. The main body includes a structure that cools the extended section by causing the gaseous fuel, which has exited the communication hole and undergone adiabatic expansion upon opening the second valve, to impinge upon the extended section. (Second configuration)

[0056] In the gaseous fuel injector of the first configuration, the extended section of the main body comprises a circumferential wall (35) and a projection (38). The circumferential wall extends from an outer circumference of the partition toward the downstream section and forms the second fuel passage. The projection extends from a position at a downstream end face of the partition toward the downstream section, and this position is radially inside the circumferential wall, with the downstream end face facing the downstream section. The partition includes the communication hole, which is located between the circumferential wall and the projection.The second valve comprises a guide section (42) which is configured to guide the gaseous fuel that has escaped from the communication hole and undergone adiabatic expansion to a radially inner side and a radially outer side of the guide section to impinge on the circumferential wall and the projection. (Third configuration)

[0057] In the gaseous fuel injection valve according to the first configuration, the extended section of the main body corresponds to a circumferential wall (35) extending from an outer periphery of the separation towards the downstream section, forming the second fuel passage. The second valve comprises a guide section (42) configured to direct the gaseous fuel, which has exited the communication hole and undergone adiabatic expansion, towards a radially outer side of the guide section to impinge upon the circumferential wall. (Fourth configuration)

[0058] In the gaseous fuel injector of the first or second configuration, the second fuel passage has a first section at an upstream end and a second section positioned downstream of the first section. The passage diameter of the first section differs from the passage diameter of the second section. The first section has an annular expanded space (S1) with a larger passage diameter than the second section. The guide section of the second valve is configured to direct the gaseous fuel, which has exited the communication hole and undergone adiabatic expansion, toward a radially outer side of the guide section and introduce the gaseous fuel into the expanded space. (Fifth configuration)

[0059] In the gaseous fuel injection valve according to the fourth configuration, the second valve has a cylindrical section (41) which is displaceable or slideable with respect to an inner circumferential surface of the main body; the expanded space is located on a radially outer side of the cylindrical section; and the cylindrical section has an opening (43) through which the expanded space is connected to an inner space located on a radially inner side of the cylindrical section. (Sixth configuration)

[0060] The gaseous fuel injector according to the fourth configuration includes the preload element (45), which pushes the second valve towards the closed position. The preload element is located in the expanded space. (Seventh configuration)

[0061] In the gaseous fuel injection valve according to one of the first to sixth configurations, the communication hole is one of several communication holes. These multiple communication holes accommodate residual gas that remains downstream of the first valve during the period between the first valve closing and the first valve subsequently opening, such that the total volume of the multiple communication holes corresponds to the volume of the residual gas.

[0062] This disclosure has been described according to exemplary embodiments; however, it is understood that the present disclosure is not limited to these embodiments or structures. The present disclosure also includes various modifications and equivalents within the scope of protection of the invention. Furthermore, various combinations and configurations, as well as other combinations or configurations comprising only one element, more than one element, or fewer than one element of the described elements, also fall within the basic concept and scope of the present disclosure. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] JP 2023-127077 A

[0001] JP 2023 - 513 065 A

[0004]

Claims

[1] Gaseous fuel injector (10) configured to inject gaseous fuel directly into a combustion chamber of an internal combustion engine, the gaseous fuel injector comprising: a main body (11, 12) which is designed in a cylindrical shape, wherein the main body comprises a fuel passage and an injection hole (15), wherein the fuel passage is located inside the main body and the injection hole is located at a pointed end of the main body, wherein the main body comprises a partition (33) which divides the fuel passage into a first fuel passage (P1) and a second fuel passage (P2), wherein the first fuel passage is an upstream section of the fuel passage and the second fuel passage is a downstream section of the fuel passage, wherein the partition has a communication hole (34) through which the first fuel passage is connected to the second fuel passage, the main body comprises a first valve (13), a second valve (14) and a sealing element (27) inside the main body, wherein the first valve is configured to open and close the communication hole from one side of the first fuel passage, the second valve is configured to open and close the communication hole from one side of the second fuel passage, and a sealing element is located between the first valve and the partition, wherein the sealing element is configured to seal an area around an opening of the communication hole. wherein the first valve is configured to be opened by a drive unit (25), and the second valve is configured to be opened in response to a pressure within the communication hole exceeding a preload force of a preload element (45) which is configured to push the second valve towards a closed position, wherein the main body comprises an extended section (35, 38) which extends from the separation towards the downstream section, and the main body includes a structure configured to cool the extended section by causing the gaseous fuel, which has escaped from the communication hole when the second valve was opened and has undergone adiabatic expansion, to impinge upon the extended section. [2] Gaseous fuel injection valve according to claim 1, wherein the extended section of the main body comprises: a circumferential wall (35) which extends from an outer periphery of the partition towards the downstream section and forms the second fuel passage; and a projection (38) which extends from a position on a downstream end face of the separation in the direction of the downstream section, wherein the position is radially inside the circumferential wall and the downstream end face is facing the downstream section, the partition has the communication hole, which is located between the perimeter wall and the projection, and the second valve comprises a guide section (42) which is configured such that it directs the gaseous fuel which has escaped from the communication hole and has undergone adiabatic expansion towards a radially inner side and a radially outer side of the guide section, so that it impinges on the circumferential wall and the projection. [3] Injection valve for gaseous fuel according to claim 1, wherein the extended section of the main body is a circumferential wall (35) which extends from an outer periphery of the separation towards the downstream section and forms the second fuel passage, and the second valve comprises a guide section (42) which is configured such that it directs the gaseous fuel which has escaped from the communication hole and has undergone adiabatic expansion towards a radially outer side of the guide section, so that it impinges on the circumferential wall. [4] Injection valve for gaseous fuel according to claim 2 or 3, wherein the second fuel passage has a first section at an upstream end and a second section which is positioned downstream of the first section, the throughput diameter of the first section differs from the throughput diameter of the second section, the first section has an annular expanded space (S1) with a larger passage diameter than the second section, and The guide section of the second valve is configured such that it guides the gaseous fuel, which has escaped from the communication hole and undergone adiabatic expansion, towards a radially outer side of the guide section and introduces the gaseous fuel into the annular expanded space. [5] Injection valve for gaseous fuel according to claim 4, wherein the second valve has a cylindrical section (41) which is displaceable with respect to an inner circumferential surface of the main body, the annular expanded space is arranged on a radially outer side of the cylindrical section, and the cylindrical section has an opening (43) through which the annularly expanded space is connected to an inner space located on a radially inner side of the cylindrical section. [6] Injection valve for gaseous fuel according to claim 4, further comprising: the preloading element (45) which is configured such that it pushes the second valve towards the closed position, the preloading element being located at the annular enlarged space. [7] Injection valve for gaseous fuel according to claim 1, wherein The communication gap is one of several communication gaps, and The communication holes are configured to absorb residual gas that remains downstream of the first valve during a period between closing the first valve and subsequently opening the first valve, such that the total volume of the communication holes corresponds to the volume of the residual gas.

Images