Internal combustion engine

Abstract

To prevent gas fuel from accumulating in the area around the ignition plug.SOLUTION: An internal combustion engine comprises an engine body 10 provided with a combustion chamber R in which a mixed gas of intake air and gas fuel is burnt, a fuel injection valve 20 which injects the gas fuel into the combustion chamber R, and an ignition plug which ignites the mixed gas. The engine body 10 has a storage hole 30 storing the fuel injection valve 20 and a communication path 35 communicating the storage hole 30 with the combustion chamber R. The ignition plug is positioned on an upper dead center side UP relative to a first central axial line C1 of the fuel injection valve 20. The communication path 35 is positioned on a lower dead center side DW relative to the first central axial line C1. A second central axial line C2 of the communication path 35 is inclined relative to the first central axial line C1 in such a way that the same approaches the lower dead center side DW along the injection direction ID of the fuel injection valve 20.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to an internal combustion engine.

Background Art

[0002] The internal combustion engine described in Patent Document 1 includes a combustion chamber, an intake port, and an exhaust port. The combustion chamber is a space where a mixture of fuel and intake air burns. The intake port is a passage for guiding intake air into the fuel chamber. The exhaust port is a passage for guiding exhaust from the combustion chamber to the outside. Further, the internal combustion engine described in Patent Document 1 includes a fuel injection valve and a spark plug. The fuel injection valve directly injects fuel into the combustion chamber without passing through the intake port. The spark plug ignites the mixture of fuel and intake air.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In an internal combustion engine as described in Patent Document 1, the temperature around the spark plug becomes relatively high. Further, in an internal combustion engine as described in Patent Document 1, assume that gaseous fuel is adopted as the fuel injected from the fuel injection valve. And generally, the ignition point of gaseous fuel is lower than that of liquid fuel. Therefore, if the gaseous fuel injected from the fuel injection valve concentrates around the spark plug, there is a risk that the combustion of the gaseous fuel will start before the ignition timing by the spark plug.

Means for Solving the Problems

[0005] One embodiment for solving the above problem is an internal combustion engine comprising: an engine body having a combustion chamber in which a mixture of intake air and gaseous fuel is burned; a fuel injection valve for injecting the gaseous fuel into the combustion chamber; and a spark plug for igniting the mixture, wherein the engine body has a housing hole for housing the fuel injection valve and a connecting passage connecting the housing hole and the combustion chamber, the spark plug is located on the top dead center side with respect to the central axis of the fuel injection valve, the connecting passage is located on the bottom dead center side with respect to the central axis of the fuel injection valve, and the central axis of the connecting passage is inclined with respect to the central axis of the fuel injection valve such that it is located on the bottom dead center side as it approaches the injection direction of the fuel injection valve. [Effects of the Invention]

[0006] With the above configuration, the gaseous fuel injected from the fuel injector is less likely to concentrate around the spark plug, thus reducing the risk of combustion of the gaseous fuel starting before the ignition timing by the spark plug. [Brief explanation of the drawing]

[0007] [Figure 1] Figure 1 is a schematic diagram of an internal combustion engine. [Figure 2] Figure 2 is an end view of the fuel injection valve. [Figure 3] Figure 3 is an enlarged end view of the cylinder head near the communication passage. [Modes for carrying out the invention]

[0008] An embodiment of an inductor component will be described below with reference to the drawings. Note that the drawings may show enlarged versions of the components for easier understanding. The dimensional ratios of the components may differ from those shown in the actual components or in other drawings.

[0009] <Overall Configuration of an Internal Combustion Engine> As shown in Figure 1, the internal combustion engine E comprises an engine body 10. The engine body 10 consists of a cylinder block 11 and a cylinder head 12. The cylinder block 11 has cylinders 11A. Cylinders 11A are cylindrical spaces. Cylinders 11A are open at the end face of the cylinder block 11. Although only one set of cylinders 11A and their associated configurations is shown in Figure 1, the internal combustion engine E has multiple cylinders 11A and their associated configurations.

[0010] The cylinder head 12 is connected to the end face of the cylinder block 11. The cylinder head 12 has a recess 12A, an intake port 12B, and an exhaust port 12C. The recess 12A is recessed on the end face of the cylinder head 12. The recess 12A is a roughly hemispherical space. The opening diameter of the recess 12A is the same as the inner diameter of the cylinder 11A. The recess 12A faces the cylinder 11A. These recesses 12A and cylinder 11A constitute a single combustion chamber R. The combustion chamber R is the space in which the intake air and the mixture of gaseous fuel are burned.

[0011] The intake port 12B is a passage for intake air supplied to the combustion chamber R. The first end of the intake port 12B is connected to the recess 12A. The second end of the intake port 12B is connected to an intake pipe (not shown). The exhaust port 12C is a passage for exhaust air discharged from the combustion chamber R. The first end of the exhaust port 12C is connected to the recess 12A. The second end of the exhaust port 12C is connected to an exhaust pipe (not shown).

[0012] The internal combustion engine E comprises a piston 13, an intake valve 14, an exhaust valve 15, and a spark plug 16. The piston 13 is located within cylinder 11A. The piston 13 reciprocates within cylinder 11A in conjunction with the combustion of the fuel-air mixture in the combustion chamber R. Although not shown in the diagram, the piston 13 is connected to the crankshaft via a connecting rod. The connecting rod and crankshaft convert the reciprocating motion of the piston 13 into rotational motion. In the following description, the direction of motion of the piston 13 when the fuel-air mixture in the combustion chamber R is compressed is referred to as the top dead center direction (UP), and the opposite direction is referred to as the bottom dead center direction (DW).

[0013] The intake valve 14 is mounted on the cylinder head 12. The intake valve 14 opens and closes the first end of the intake port 12B. The intake valve 14 operates in synchronization with the reciprocating motion of the piston 13. The exhaust valve 15 is mounted on the cylinder head 12. The exhaust valve 15 opens and closes the first end of the exhaust port 12C. The exhaust valve 15 operates in synchronization with the reciprocating motion of the piston 13.

[0014] The spark plug 16 is mounted in the cylinder head 12. The spark plug 16 is located between the intake port 12B and the exhaust port 12C. The tip of the spark plug 16 is located in the recess 12A. The spark plug 16 ignites the fuel-air mixture in the combustion chamber R by spark discharge. The spark plug 16 ignites the fuel-air mixture in sync with the reciprocating motion of the piston 13.

[0015] The internal combustion engine E is equipped with a fuel injector 20. The fuel injector 20 is mounted on the cylinder head 12. The fuel injector 20 injects gaseous fuel directly into the combustion chamber R without passing through the intake port 12B. An example of gaseous fuel is hydrogen.

[0016] As shown in Figure 2, the fuel injector 20 has a cylindrical body 21 and a needle valve 22. The cylindrical body 21 is generally cylindrical in shape. The first central axis C1, which is the central axis of the cylindrical body 21, is the central axis of the fuel injector 20. The cylindrical body 21 has an injection port 21A at the end in the direction along the first central axis C1. The injection port 21A is an opening for injecting gaseous fuel from inside the cylindrical body 21 to the outside of the fuel injector 20. The injection port 21A is circular in shape. The center of the injection port 21A is located on the first central axis C1.

[0017] The needle valve 22 has a valve body 22A and a diamond-like carbon film 22B. The valve body 22A is roughly rod-shaped. The valve body 22A is located inside the cylindrical body 21. The valve body 22A is capable of reciprocating along the first central axis C1 by an electromagnetic solenoid (not shown). The reciprocating motion of the valve body 22A opens and closes the injection port 21A of the cylindrical body 21 on the inside of the cylindrical body 21. The diamond-like carbon film 22B covers the tip surface of the valve body 22A. In other words, the diamond-like carbon film 22B is located on the surface of the valve body 22A facing the injection port 21A. The diamond-like carbon film 22B is an amorphous film mainly composed of one or more elements selected from hydrocarbons and carbon. The diamond-like carbon film 22B is sometimes called a hard carbon film. In Figure 2, the diamond-like carbon film 22B is shown with a thick line.

[0018] <Structure around the fuel injector> As shown in Figure 3, the cylinder head 12 has a housing hole 30 for housing the fuel injector 20. The housing hole 30 is located on the bottom dead center DW side with respect to the intake port 12B. The housing hole 30 is a roughly cylindrical space. The housing hole 30 also has a bottom surface 30A. The bottom surface 30A is the inner surface of the housing hole 30 on the combustion chamber R side. The central axis of the housing hole 30 is inclined so that it is located on the bottom dead center DW side as it approaches the combustion chamber R.

[0019] The fuel injector 20 is located within the housing hole 30. The nozzle 21A of the cylindrical body 21 faces the bottom surface 30A of the housing hole 30. The first central axis C1 of the cylindrical body 21 coincides with the central axis of the housing hole 30. In other words, the first central axis C1 is inclined such that it is located towards the bottom dead center direction DW as it approaches the injection direction ID of the gaseous fuel from the fuel injector 20. As a result, the spark plug 16 described above is located towards the top dead center direction UP with respect to the first central axis C1. The tip of the cylindrical body 21 on the nozzle 21A side is separated from the bottom surface 30A of the housing hole 30. In other words, a gap S is created between the fuel injector 20 and the bottom surface 30A of the housing hole 30.

[0020] The cylinder head 12 has a communication passage 35 that connects the accommodation hole 30 and the combustion chamber R. The communication passage 35 is a cylindrical space. The opening 35A on the accommodation hole 30 side in the communication passage 35 is located on the bottom surface 30A of the accommodation hole 30. Also, the communication passage 35 is located on the bottom dead center direction DW side with respect to the first central axis C1. Further, the second central axis C2, which is the central axis of the communication passage 35, is inclined so as to be located on the bottom dead center direction DW side toward the injection direction ID of the fuel injection valve 20 with respect to the first central axis C1. Also, among the angles formed by the second central axis C2 of the communication passage 35 and the first central axis C1 of the fuel injection valve 20, the angle on the injection direction ID side and the bottom dead center direction DW side is defined as a specific angle θ. At this time, the specific angle θ is 45 degrees or less.

[0021] Also, let the projection range PR be the range obtained by projecting the opening 35A on the accommodation hole 30 side in the communication passage 35 onto the fuel injection valve 20 in the direction in which the opening 35A faces. At this time, the injection port 21A of the fuel injection valve 20 is located outside the projection range PR. That is, the region surrounded by the edge of the injection port 21A does not overlap with the projection range PR. Note that the "direction in which the opening 35A on the accommodation hole 30 side of the communication passage 35 faces" is the direction of the line of sight when the apparent area of the opening 35A of the communication passage 35 is the largest when viewed from the inside of the communication passage 35. In this embodiment, the "direction in which the opening 35A of the communication passage 35 faces" is the direction along the second central axis C2 and toward the fuel injection valve 20 side from the inside of the communication passage 35.

[0022] <Operation of the embodiment> When the needle valve 22 of the fuel injection valve 20 is in the open state, the gaseous fuel in the cylinder body 21 is injected into the gap S. A part of the gaseous fuel injected at this time collides with the bottom surface 30A of the accommodation hole 30. However, since the gaseous fuel is in a vaporized state, even if it collides with the bottom surface 30A, the possibility that the gaseous fuel condenses on the surface of the bottom surface 30A is low. The gaseous fuel injected into the gap S reaches the combustion chamber R through the communication passage 35 following the negative pressure in the cylinder 11A generated when the piston 13 moves toward the bottom dead center direction DW side.

[0023] <Effect of the embodiment> (1) In the above embodiment, the communication passage 35 is located on the bottom dead center DW side with respect to the first central axis C1. In other words, with respect to the first central axis C1, the gaseous fuel flows into the combustion chamber R relatively on the bottom dead center DW side. Therefore, it is possible to prevent the gaseous fuel from concentrating on the top dead center UP side within the combustion chamber R, i.e., around the spark plug 16.

[0024] (2) In the above embodiment, the second central axis C2, which is the central axis of the communication passage 35, is inclined with respect to the first central axis C1 such that it is located towards the bottom dead center direction DW as it approaches the injection direction ID of the fuel injector 20. Therefore, the gaseous fuel flowing into the combustion chamber R can be given a flow that is directed towards the bottom dead center direction DW as a whole. This prevents the gaseous fuel from concentrating in the combustion chamber R on the top dead center direction UP side, i.e., around the spark plug 16.

[0025] (3) In the above embodiment, the diamond-like carbon film 22B is located on the surface of the valve body 22A, on the portion facing the injection port 21A. Therefore, even if high-temperature combustion gas flows into the gap S from inside the combustion chamber R, the diamond-like carbon film 22B can protect the valve body 22A.

[0026] (4) In the above embodiment, the nozzle 21A of the fuel injector 20 is located outside the projection range PR. Therefore, when combustion gas flows into the gap S from the combustion chamber R side through the communication passage 35, the combustion gas first collides with the outer surface of the cylindrical body 21. In other words, the diamond-like carbon film 22B exposed from the nozzle 21A is highly likely to escape direct impact from the combustion gas. Therefore, it is possible to prevent the diamond-like carbon film 22B from deteriorating due to contact with the combustion gas.

[0027] (5) In the above embodiment, the specific angle θ formed by the second central axis C2 of the communication passage 35 and the first central axis C1 of the fuel injector 20 is 45 degrees or less. With this angle setting, the gaseous fuel can be guided to the communication passage 35 and the combustion chamber R without excessively obstructing the flow in the injection direction ID side from the fuel injector 20.

[0028] <Example of changes> This embodiment can be implemented with the following modifications. Furthermore, this embodiment and the following modifications can be combined with each other to the extent that they do not contradict each other technically.

[0029] The configuration of the internal combustion engine E can be modified as appropriate. For example, in addition to the fuel injector 20, the internal combustion engine E may be equipped with a port injector that injects fuel into the intake port 12B. Alternatively, the internal combustion engine E may be equipped with a water injector that injects cooling water into the intake port 12B.

[0030] The position of the fuel injector 20 can be adjusted as appropriate, provided that gaseous fuel can be injected into cylinder 11A. For example, the housing hole 30 that accommodates the fuel injector 20 may be located on the bottom dead center DW side with respect to the exhaust port 12C.

[0031] The fuel injection valve 20 may have multiple injection ports 21A. In this case, it is preferable that one or more of the multiple injection ports 21A are located outside the projection range PR. • Part or all of the injection port 21A of the fuel injection valve 20 may be located within the projection range PR. In this case as well, the effects of (1) and (2) described above can be obtained.

[0032] The shape of the connecting passage 35 is not limited to a cylindrical shape. For example, the shape of the connecting passage 35 may be bent or curved in the middle. The cylinder head 12 may have other communication passages in addition to the communication passage 35 of the above embodiment. In this case, the other communication passages may be located on the UP side in the top dead center direction with respect to the first central axis C1, and may not be inclined with respect to the first central axis C1.

[0033] The diamond-like carbon film 22B may be omitted in the needle valve 22. Alternatively, another protective film may be used in place of the diamond-like carbon film 22B in the needle valve 22.

[0034] The specified angle θ is not limited to 45 degrees or less. In other words, the specified angle θ may exceed 45 degrees. <Note> The technical concepts that can be derived from the above embodiments and modifications are described below.

[0035] [Note 1] An engine body having a combustion chamber in which an intake air and a mixture of gaseous fuel are burned, A fuel injection valve for injecting the gaseous fuel into the combustion chamber, A spark plug that ignites the aforementioned fuel mixture, It is equipped with, The engine body has a housing hole for housing the fuel injection valve and a connecting passage between the housing hole and the combustion chamber. The spark plug is located on the top dead center side with respect to the central axis of the fuel injection valve. The aforementioned communication passage is located on the bottom dead center side with respect to the central axis of the fuel injection valve, The central axis of the communication passage is inclined with respect to the central axis of the fuel injector such that it is located towards the bottom dead center direction as it moves in the injection direction of the fuel injector. Internal combustion engine.

[0036] [Note 2] The fuel injection valve has an injection port for the gaseous fuel, When the opening on the receiving hole side of the communication passage is projected onto the fuel injection valve in the direction the opening faces, the injection port is located outside the projection range of the opening. The internal combustion engine described in Appendix 1.

[0037] [Note 3] The fuel injection valve is equipped with a needle valve that opens and closes the injection port. The needle valve has a diamond-like carbon film on the portion facing the injection port. An internal combustion engine as described in Appendix 1 or 2.

[0038] [Note 4] The angle formed by the central axis of the communication passage and the central axis of the fuel injector, on the side of the gaseous fuel injection direction and the bottom dead center direction, is 45 degrees or less. An internal combustion engine as described in any of the appendices 1 to 3. [Explanation of Symbols]

[0039] E...Internal combustion engine 10…Engine body 12…Cylinder head 16... Spark plug 20…Fuel injector 30…Containment port 35…Communication path C1…First central axis line C2…Second central axis line

Claims

1. An engine body having a combustion chamber in which an intake air and a mixture of gaseous fuel are burned, A fuel injection valve for injecting the gaseous fuel into the combustion chamber, A spark plug that ignites the aforementioned fuel mixture, It is equipped with, The engine body has a housing hole for housing the fuel injection valve and a connecting passage between the housing hole and the combustion chamber. The spark plug is located on the top dead center side with respect to the central axis of the fuel injection valve. The aforementioned communication passage is located on the bottom dead center side with respect to the central axis of the fuel injection valve, The central axis of the communication passage is inclined with respect to the central axis of the fuel injector such that it is located towards the bottom dead center direction as it approaches the injection direction of the fuel injector. The fuel injection valve has an injection port for the gaseous fuel, When the opening on the receiving hole side of the communication passage is projected onto the fuel injection valve in the direction the opening faces, the injection port is located outside the projection range of the opening. Internal combustion engine.

2. The fuel injection valve is equipped with a needle valve that opens and closes the injection port. The needle valve has a diamond-like carbon film on the portion facing the injection port. The internal combustion engine according to claim 1.

3. The angle formed by the central axis of the communication passage and the central axis of the fuel injector, on the side of the gaseous fuel injection direction and the bottom dead center direction, is 45 degrees or less. The internal combustion engine according to claim 1.

Images