Internal combustion engine
The internal combustion engine design addresses foreign matter-induced damage and jamming by using a smaller combustion chamber opening and a decreasing passage area to ensure smooth fuel flow and reduce foreign matter entry, enhancing engine reliability.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- TOYOTA JIDOSHA KK
- Filing Date
- 2023-07-13
- Publication Date
- 2026-05-18
AI Technical Summary
Foreign matter entering the combustion chamber in internal combustion engines can cause damage and jamming of the fuel injection valve due to backward flow through the communication passage.
The internal combustion engine design includes a housing hole for the fuel injection valve with a connecting passage where the opening on the combustion chamber side has a smaller area than the opening on the housing hole side, and the passage cross-sectional area decreases continuously, ensuring a smooth flow path for gaseous fuel and minimizing foreign matter entry.
This configuration reduces the likelihood of damage to the fuel injection valve and prevents jamming by minimizing foreign matter entry and maintaining efficient fuel flow to the combustion chamber.
Smart Images
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Abstract
Description
Technical Field
[0001] The present invention relates to an internal combustion engine.
Background Art
[0002] The internal combustion engine of Patent Document 1 includes a combustion chamber and a fuel injection valve. The combustion chamber is a space for the mixture of intake air and fuel to burn. The fuel injection valve directly injects fuel into the combustion chamber. Further, the internal combustion engine of Patent Document 1 includes a communication passage through which the fuel injected from the fuel injection valve flows. The communication passage opens toward the combustion chamber. Therefore, the fuel injected from the fuel injection valve reaches the combustion chamber through the communication passage.
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, foreign matter may enter the combustion chamber from the outside, or deposits on the inner surface of the combustion chamber may peel off and become foreign matter. When such foreign matter flows backward through the communication passage and reaches the fuel injection valve, it may cause damage and jamming of the fuel injection valve.
Means for Solving the Problems
[0005] To solve the above problems, the present invention provides an internal combustion engine comprising: an engine body having a combustion chamber in which a mixture of intake air and gaseous fuel is burned; and a fuel injection valve for injecting the gaseous fuel into the combustion chamber, 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, and when the opening on the housing hole side of the connecting passage is designated as the first opening and the opening on the combustion chamber side of the connecting passage is designated as the second opening, the opening area of the second opening is smaller than the opening area of the first opening. [Effects of the Invention]
[0006] With the above configuration, foreign matter is less likely to enter the communication passage from the combustion chamber side, thus reducing the likelihood of damage to or jamming of the fuel injection valve due to foreign matter. [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 will be described below with reference to the drawings. Note that the drawings may show components enlarged for ease of understanding. The dimensional ratios of the components may differ from those in the actual components or those shown 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 in the end face on the cylinder block 11 side. 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 central axis C1 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 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 opening of the injection port 21A is located on the 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 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. 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 central axis C1 of the cylindrical body 21 coincides with the central axis of the housing hole 30. In other words, the central axis C1 is inclined so that it is located towards the bottom dead center direction DW as it approaches the direction of gaseous fuel injection from the fuel injector 20. The tip of the cylindrical body 21 on the nozzle 21A side is slightly 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 frustum-shaped space. Hereinafter, the opening on the accommodation hole 30 side in the communication passage 35 is referred to as the first opening 35A. Also, the opening on the combustion chamber R side in the communication passage 35 is referred to as the second opening 35B.
[0021] The central axis of the communication passage 35 coincides with the central axis C1 of the fuel injection valve 20. Therefore, the entire portion from the first opening 35A to the second opening 35B in the communication passage 35 is located on the central axis C1. More specifically, the opening center of the first opening 35A, the opening center of the second opening 35B, and the opening center of the injection port 21A in the fuel injection valve 20 are all located on the central axis C1.
[0022] The opening area of the second opening 35B is smaller than the opening area of the first opening 35A. Specifically, both the second opening 35B and the first opening 35A are circular. And the diameter of the second opening 35B is half of the diameter of the first opening 35A. Therefore, the opening area of the second opening 35B is one-fourth of the opening area of the first opening 35A. Note that the "opening area" is the largest area among the apparent areas of the regions surrounded by the opening edges when the first opening 35A or the second opening 35B is viewed from various directions. In this embodiment, the areas when viewed in a direction parallel to the central axis C1 are the opening area of the first opening 35A and the opening area of the second opening 35B.
[0023] Also, since the communication passage 35 is frustum-shaped, the flow path cross-sectional area of the communication passage 35 continuously decreases from the first opening 35A toward the second opening 35B. That is, when the communication passage 35 is viewed in cross-section with a cross-section including its central axis, the inner surface of the communication passage 35 is linear or curved and inclined with respect to the central axis of the communication passage 35. In this embodiment, the flow path cross-sectional area of the communication passage 35 decreases by a certain area from the first opening 35A toward the second opening 35B. Note that the "flow path cross-sectional area" is the area inside the communication passage 35 in a cross-section orthogonal to the central axis of the communication passage 35.
[0024] <Operation of the embodiment> When the needle valve 22 of the fuel injection valve 20 opens, gaseous fuel in the cylinder 21 is injected from the injection port 21A. As described above, the opening centers of the first opening 35A, the second opening 35B, and the injection port 21A of the fuel injection valve 20 are all located on the central axis C1. Therefore, the injected gaseous fuel quickly reaches the combustion chamber R via the communication passage 35, according to the negative pressure in the cylinder 11A generated when the piston 13 moves towards the bottom dead center DW.
[0025] Furthermore, since the cross-sectional area of the communication passage 35 decreases continuously as it approaches the second opening 35B, some of the injected gaseous fuel collides with the inner surface of the communication passage 35. However, since the gaseous fuel is in a vaporized state, even if it collides with the inner surface of the communication passage 35, it is unlikely that the gaseous fuel will condense on the inner surface of the communication passage 35.
[0026] <Effects of the Embodiment> (1) According to the above embodiment, the opening area of the second opening 35B is smaller than the opening area of the first opening 35A. Therefore, even if foreign matter enters the combustion chamber R, it is less likely for the foreign matter to enter the communication passage 35 compared to the case where the opening area of the second opening 35B is greater than or equal to the opening area of the first opening 35A. Therefore, the possibility that foreign matter that enters the housing hole 30 through the communication passage 35 will cause damage to the fuel injection valve 20 and jamming can be reduced.
[0027] (2) According to the above embodiment, the flow area of the communication passage 35 decreases continuously from the first opening 35A to the second opening 35B. In other words, since there is no clear step on the inner surface of the communication passage 35, the inner surface has a smooth shape. Therefore, it is possible to prevent the inner surface of the communication passage 35 from obstructing the flow of gaseous fuel injected from the injection port 21A of the fuel injection valve 20. Furthermore, even if foreign matter enters the containment hole 30, it is easy to guide the foreign matter into the combustion chamber R in accordance with the flow of gaseous fuel.
[0028] (3) According to the above embodiment, the injection port 21A of the fuel injection valve 20 is located on the central axis C1. Furthermore, the entire section of the communication passage 35 from the first opening 35A to the second opening 35B is located on the central axis C1. That is, a straight flow path is secured from the injection port 21A through the communication passage 35 to the combustion chamber R. Therefore, even though the opening area of the second opening 35B is relatively small, excessive obstruction of the flow of gaseous fuel to the combustion chamber R can be prevented.
[0029] (4) According to the above embodiment, the opening area of the second opening 35B is less than half, specifically one-quarter, of the opening area of the first opening 35A. By making the opening area of the second opening 35B considerably smaller in this way, it is possible to suppress the intrusion of large foreign objects into the containment hole 30 that could lead to damage to the fuel injection valve 20.
[0030] <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.
[0031] 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.
[0032] 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.
[0033] The fuel injection valve 20 may have multiple injection ports 21A. Furthermore, the injection ports 21A may be oriented in a direction inclined with respect to the central axis C1. - There does not need to be a gap S between the fuel injector 20 and the bottom surface 30A of the housing hole 30. The presence or absence of a gap S is irrelevant as long as the injection port 21A of the fuel injector 20 and the communication passage 35 are connected.
[0034] The shape of the connecting passage 35 is not limited to a frustoconical shape. For example, the shape of the connecting passage 35 may be an elliptical frustoconical shape or a polygonal frustoconical shape. Furthermore, the shape of the connecting passage 35 may be bent or curved in the middle.
[0035] The flow area of the connecting passage 35 is not limited to continuously decreasing toward the second opening 35B. For example, the flow area of the connecting passage 35 may decrease in stages from the first opening 35A toward the second opening 35B. Even in this case, the opening area of the second opening 35B will be smaller than the opening area of the first opening 35A.
[0036] Furthermore, if the opening area of the second opening 35B is smaller than the opening area of the first opening 35A, the flow area in the middle of the connecting passage 35 is irrelevant. For example, at a point in the middle of the connecting passage 35, the flow area may be larger than both the opening area of the second opening 35B and the opening area of the first opening 35A.
[0037] The opening centers of the first opening 35A and the second opening 35B do not necessarily have to be located on the central axis C1. Furthermore, the entirety of the first opening 35A and the entirety of the second opening 35B do not necessarily have to be located on the central axis C1.
[0038] The opening area of the second opening 35B does not need to be larger than the opening area of the first opening 35A. However, from the standpoint of preventing large foreign objects that could lead to damage to the fuel injection valve 20 from entering the containment hole 30, it is preferable that the opening area of the second opening 35B be less than or equal to half the opening area of the first opening 35A.
[0039] The cylinder head 12 may have other communication passages in addition to the communication passage 35 of the above embodiment. In this case, the relative sizes of the opening areas at both ends of the other communication passages do not matter.
[0040] 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.
[0041] <Note> The technical concepts that can be derived from the above embodiments and modifications are described below. <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, 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. When the opening on the receiving hole side of the communication passage is designated as the first opening, and the opening on the combustion chamber side of the communication passage is designated as the second opening, The opening area of the second opening is smaller than the opening area of the first opening. Internal combustion engine.
[0042] <Note 2> The flow path area of the aforementioned passage decreases continuously from the first opening to the second opening. The internal combustion engine described in Appendix 1.
[0043] <Note 3> The fuel injection valve has an injection port for the gaseous fuel, The injection port is located on the central axis of the fuel injection valve, and the entire communication passage from the first opening to the second opening is located on the central axis of the fuel injection valve. An internal combustion engine as described in Appendix 1 or 2.
[0044] <Note 4> The opening area of the second opening is less than or equal to half the opening area of the first opening. An internal combustion engine as described in any one of the appendices 1 to 3. [Explanation of symbols]
[0045] E...Internal combustion engine 10…Engine body 12…Cylinder head 20…Fuel injector 30…Containment port 35…Communication path 35A…1st opening 35B…Second opening R...combustion chamber
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, It is equipped with, The engine body comprises a cylinder block having cylinders, and a cylinder head facing the cylinders and having recesses that together with the cylinders constitute the combustion chamber. The cylinder head has a housing hole for housing the fuel injection valve and a connecting passage between the housing hole and the combustion chamber. When the opening on the receiving hole side of the communication passage is designated as the first opening, and the opening on the combustion chamber side of the communication passage is designated as the second opening, The opening area of the second opening is smaller than the opening area of the first opening. The flow path area of the aforementioned passage decreases continuously from the first opening to the second opening. Internal combustion engine.
2. The fuel injection valve has an injection port for the gaseous fuel, The injection port is located on the central axis of the fuel injection valve, and the entire communication passage from the first opening to the second opening is located on the central axis of the fuel injection valve. The internal combustion engine according to claim 1.
3. The opening area of the second opening is less than or equal to half the opening area of the first opening. The internal combustion engine according to claim 1.