internal combustion engine

Abstract

To promote taking of intake air into fuel spray.SOLUTION: An internal combustion engine 10 includes: a cylinder head 14 covering a combustion chamber 11; and a jetting part 18 projecting from an undersurface 14a of the cylinder head 14 to jet fuel. The cylinder head 14 includes a recess 50 that is provided in a periphery of the jetting part 18 at the undersurface 14a along a circumferential direction.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] In the internal combustion engine of Patent Document 1 listed below, a cross-shaped groove is provided on the lower surface of the cylinder head in order to promote mixing of the fuel spray injected from the injection portion with the intake air. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Utility Model Application Publication No. 62-95130 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the above technology, since the grooves are arranged in a cross shape, if the fuel is injected in many directions from the injection part, there is a risk that the intake air will not be sufficiently taken in by the fuel spray, resulting in insufficient mixing of the fuel spray and the intake air.

[0005] The present invention has been made in consideration of these points, and has an object to make it possible to promote the intake of intake air into fuel spray. [Means for solving the problem]

[0006] One aspect of the present invention provides an internal combustion engine comprising: a cylinder head covering a combustion chamber; and an injection portion protruding from a lower surface of the cylinder head and injecting fuel, the cylinder head having a recess provided in the lower surface along a circumferential direction around the injection portion.

[0007] The recess may be provided on the lower surface over one circumference in the circumferential direction.

[0008] The width of the recess may be greater than the depth of the recess. The engine may further include an intake valve for supplying intake air to the combustion chamber, and the width of the recess may be greater than half the distance between the injection portion and the intake valve.

[0009] The depth of the recess may be greater than the distance from the lower surface to the tip of the ejection portion.

[0010] The width of the recess may be greater than the diameter of the ejection portion. Furthermore, a width of a portion of the recess facing a region through which the fuel injected from the injection portion passes may be larger than a width of a portion of the recess other than the facing portion.

[0011] The facing portions may be provided at predetermined intervals in the circumferential direction of the recess. [Effects of the Invention]

[0012] The present invention has the effect of promoting the intake of intake air into the fuel spray. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a schematic diagram showing the configuration of an internal combustion engine 10 according to one embodiment. [Figure 2] FIG. 2 is a schematic diagram showing the configuration of an injector 17 and its surroundings. [Figure 3] FIG. 10 is a schematic diagram showing a comparative example. [Figure 4] 2 is a schematic diagram showing the configuration of a lower surface 14a of a cylinder head 14. FIG. [Figure 5] FIG. 10 is a schematic diagram showing a recess 60 according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0014] <Configuration of an internal combustion engine> FIG. 1 is a schematic diagram showing the configuration of an internal combustion engine 10 according to one embodiment. Here, the internal combustion engine 10 is mounted on a vehicle 1, but is not limited to this and may be mounted on a ship, for example. The vehicle 1 is, for example, a truck. As shown in FIG. 1, the vehicle 1 has the internal combustion engine 10, an intake passage 30, and an exhaust passage 40.

[0015] The internal combustion engine 10 is, for example, a diesel engine. The internal combustion engine 10 generates power by burning and expanding a fuel mixture in a combustion chamber 11. The internal combustion engine 10 has a cylinder block 12, a cylinder head 14, an intake manifold 20, and an exhaust manifold 25.

[0016] A cylinder 12a is formed in the cylinder block 12, and the cylinder 12a accommodates a reciprocating piston 13. Specifically, the cylinder 12a is a cylindrical cylinder liner. Although only one cylinder 12a is shown in FIG. 1, a plurality of cylinders 12a are arranged in the depth direction of the paper surface of FIG. 1.

[0017] The cylinder head 14 covers the upper part of the cylinder 12a (specifically, the combustion chamber 11). An intake port 15a, an exhaust port 15b, an intake valve 16a, an exhaust valve 16b, and an injector 17 are provided in the cylinder head 14.

[0018] The intake port 15a introduces intake air into the combustion chamber 11. The exhaust port 15b discharges exhaust gas from the combustion chamber 11. The intake valve 16a adjusts the supply of intake air to the combustion chamber 11 by opening and closing the intake port 15a. The exhaust valve 16b adjusts the outflow of exhaust gas from the combustion chamber 11 by opening and closing the exhaust port 15b. The injector 17 injects fuel so that the compressed air in the combustion chamber 11 mixes with the fuel when the piston 13 is at top dead center. The injector 17 has an injection part 18 at its tip that injects fuel.

[0019] The intake manifold 20 is a manifold for distributing intake air to the combustion chambers 11 of the cylinders 12a of the internal combustion engine 10. The intake manifold 20 is connected to the intake ports 15a of the cylinder head .

[0020] The exhaust manifold 25 is a collecting pipe that collects exhaust gases discharged from the combustion chambers 11 of the cylinders 12a of the internal combustion engine 10. The exhaust manifold 25 is connected to the exhaust ports 15b of the cylinder head 14.

[0021] The intake passage 30 is a flow path through which intake air (air) flows to be introduced into the internal combustion engine 10. The intake passage 30 is connected to the intake manifold 20. The air flowing through the intake passage 30 is introduced into each cylinder 12a of the internal combustion engine 10 via the intake manifold 20.

[0022] The exhaust passage 40 is a flow path that guides exhaust gas from the internal combustion engine 10 to the atmosphere. The exhaust passage 40 is connected to the exhaust manifold 25. The exhaust gas discharged from the combustion chamber 11 of each cylinder 12a of the internal combustion engine 10 flows into the exhaust passage 40 via the exhaust manifold 25.

[0023] <Configuration of the Surrounding Area of the Injection Portion 18> FIG. 2 is a schematic diagram showing the configuration of the ejection unit 18 and its surrounding area.

[0024] The injection section 18 protrudes downward from the lower surface 14a of the cylinder head 14. The injection section 18 is provided with a plurality of nozzles 18a so as to inject fuel in a plurality of injection directions as shown in Fig. 2. The injection section 18 injects fuel radially so that the angle between each injection direction is, for example, 60 degrees in the circumferential direction.

[0025] The fuel injected by the injection unit 18 spreads as a fuel spray as it moves away from the injection unit 18. The area R enclosed by a triangle in FIG. 2 indicates the area of the fuel spray. The injection unit 18 injects fuel so that the fuel spray spreads along the underside 14a of the cylinder head 14. The surrounding intake air is drawn into the fuel spray, and the intake air and fuel spray are mixed. The intake air is drawn into the fuel spray as indicated by the dashed arrow in FIG. 2.

[0026] In this embodiment, in order to facilitate the intake of air between the lower surface 14a of the cylinder head 14 and the fuel spray into the fuel spray, a recess 50 is provided on the lower surface 14a around the injection portion 18. By providing the recess 50, the space above the fuel spray (the space between the lower surface 14a and the fuel spray) becomes wider, so that when the injection portion 18 injects fuel, the intake of air is more easily taken into the fuel spray through that space.

[0027] Here, further explanation will be given in comparison with a comparative example shown in FIG. FIG. 3 is a schematic diagram showing a comparative example. The lower surface 114a of the cylinder head 114 according to the comparative example does not have the recess 50, and the lower surface 114a is flat. In this case, as shown in FIG. 3, the space above the fuel spray is narrowed. As a result, a large amount of intake air is taken in from the space below the fuel spray, while a small amount of intake air is taken in from the space above the fuel spray. This may result in insufficient mixing of the fuel spray and the intake air. Furthermore, since it takes time for the intake air to be taken in by the fuel spray, the combustion of the mixture is prolonged.

[0028] In contrast, in this embodiment, by providing recesses 50 around the injection portion 18 on the underside 14a, the space above the fuel spray is widened, making it easier for intake air to flow through this space. As a result, as shown in FIG. 2, when the injection portion 18 injects fuel, the amount of intake air taken into the fuel spray from this space increases. As a result, mixing of the fuel spray and intake air is promoted. By promoting mixing of the fuel spray and intake air, combustion of the mixture becomes more active in a short period of time, and the work of pushing down the piston 13 by the combustion of the mixture becomes greater (i.e., torque increases), thereby improving fuel efficiency.

[0029] (Detailed configuration of recess 50) The specific configuration of the recess 50 will be described with reference to FIGS. Fig. 4 is a schematic diagram showing the configuration of the lower surface 14a of the cylinder head 14. In Fig. 4, the recessed portion 50 is hatched to make the position of the recessed portion 50 easier to understand. Note that Fig. 2 is a view taken along the arrow AA in Fig. 4.

[0030] The recesses 50 are provided on the lower surface 14a along the circumferential direction around the injection portion 18. When the recesses 50 are provided along the circumferential direction in this way, the intake air tends to flow along the recesses 50, and therefore the intake air tends to be taken in for each of the fuel sprays injected radially from the injection portion 18 (specifically, at 60-degree intervals in the circumferential direction).

[0031] The cross-sectional shape of the recess 50 is trapezoidal here as shown in Fig. 2. However, the cross-sectional shape of the recess 50 is not limited to this, and may be rectangular or semicircular, for example. By providing the recess 50 with the above cross-sectional shape, the space above the fuel spray is widened and intake air flows more easily within the recess 50.

[0032] As shown in Fig. 4, the recess 50 is a groove provided around the entire circumference of the lower surface 14a. In other words, the recess 50 is a groove provided in an annular shape so as to surround the injection part 18. This allows the intake air to flow easily along the recess 50, making it easier for the intake air to be taken into each of the fuel sprays radially injected from the injection part 18. As a result, mixing of the radially injected fuel sprays with the intake air is promoted. However, without being limited to the above, the recesses 50 may be provided at predetermined intervals in the circumferential direction. In this case, it is desirable that the recesses 50 be provided above the fuel spray injected from the injection portion 18.

[0033] 2, the width L1 of the recess 50 is greater than the depth L2 of the recess 50. In this case, a wide recess 50 is provided in the radial direction (fuel injection direction) of the injection part 18, and the area where intake air is taken in for the fuel spray injected from the injection part 18 is widened. As a result, the fuel spray and intake air are more likely to mix over a wide area, and mixing is promoted.

[0034] The width L1 of the recess 50 is larger than the diameter of the injection portion 18. Furthermore, the width L1 of the recess 50 is larger than half the distance between the injection portion 18 and the intake valve 16a (or the exhaust valve 16b). Specifically, as shown in FIG. 2, the recess 50 is provided in most of the area between the injection portion 18 and the intake valve 16a (or the exhaust valve 16b) on the lower surface 14a. In this case, the recess 50 is formed over a wide area above the fuel spray injected from the injection portion 18, so that a large amount of intake air is taken in relative to the fuel spray. The fuel spray spreads more the farther it is from the injection part 18, and therefore intake air is more likely to be taken into the fuel spray at locations that are far from the injection part 18. In this embodiment, the recessed parts 50 are formed up to positions adjacent to the intake valve 16a and the exhaust valve 16b in the radial direction (the injection direction of the fuel spray), and therefore intake air near the intake valve 16a and the exhaust valve 16b is more likely to be taken into the fuel spray.

[0035] Depth L2 of recess 50 is greater than the distance from lower surface 14a to the tip of injection portion 18. Specifically, depth L2 of recess 50 is greater than the distance from lower surface 14a to the nozzle 18a of injection portion 18. Even if the amount of protrusion of the injection portion from lower surface 14a is small, by making depth L2 of recess 50 greater than this amount of protrusion, it becomes easier to ensure a space through which intake air flows, and the intake air becomes more easily taken into the fuel spray. However, the depth L2 of the recess 50 is not limited to the above, and may be smaller than the distance from the lower surface 14a to the tip of the ejection portion 18, and may be larger than half of this distance.

[0036] (Variation) 5 is a schematic diagram showing a recess 60 according to a modified example. Similar to the recess 50 described above, the recess 60 according to the modified example is provided around the injection portion 18 on the underside 14a of the cylinder head 14. The recess 60 also functions to facilitate intake air into the fuel spray injected from the injection portion 18. The recess 60 has a wide portion 62 and a communicating portion 64.

[0037] The wide portion 62 is a portion that is wide in the radial direction of the recess 60. The wide portion 62 is a portion that faces the area through which the fuel spray injected from the injection portion 18 passes. In other words, the wide portion 62 is formed in the space above the fuel spray, and intake air within the wide portion 62 is taken into the fuel spray. Because the radial direction of the recess 60 is the injection direction of the fuel spray, providing the wide portion 62 that is wide in the radial direction increases the amount of intake air taken into the fuel spray.

[0038] A plurality of wide portions 62 are provided. The width of each wide portion 62 is the same as the width of the recess 50 described above. The depth of each wide portion 62 is the same as the depth of the recess 50. However, this is not limited to the above, and the width and depth of each wide portion 62 may be greater than the width and depth of the recess 60.

[0039] The communicating portion 64 is a portion that connects the wide portions 62 together in the circumferential direction. The communicating portion 64 serves as a flow path through which intake air flows toward the wide portions 62. Providing the communicating portion 64 makes it easier for intake air to flow between the multiple wide portions 62. The radial width of the communicating portion 64 is smaller than the radial width of the wide portions 62. Meanwhile, the depth of the communicating portion 64 is the same as the depth of the wide portions 62. However, this is not limited to this, and the depth of the communicating portion 64 may be greater than the depth of the wide portions 62.

[0040] A plurality of wide portions 62 are provided at predetermined intervals in the circumferential direction of the recess 60. As an example, six wide portions 62 are provided at 60-degree intervals. The wide portions 62 are provided above each of the fuel sprays radially injected from the injection port 18, as indicated by the dashed arrows in FIG. 5 .

[0041] <Effects of this embodiment> The internal combustion engine 10 of the above-described embodiment has a cylinder head 14 that covers the combustion chamber 11, and an injection portion 18 that protrudes from the lower surface of the cylinder head 14 and injects fuel. The cylinder head 14 also has a recess 50 that is provided in the lower surface 14a around the injection portion 18 in the circumferential direction. By providing the recesses 50, the space above the fuel spray injected from the injection portion 18 (the space between the lower surface 14a and the fuel spray) becomes wider, so that when the injection portion 18 injects fuel, intake air is more easily taken into the fuel spray through this space. Furthermore, when the recesses 50 are provided along the circumferential direction, the intake air is more easily able to flow along the recesses 50, so that the intake air is more easily taken into each of the fuel sprays injected radially from the injection portion 18. As a result, mixing of the fuel spray and the intake air is promoted.

[0042] The present invention has been described above using embodiments, but the technical scope of the present invention is not limited to the scope described in the above embodiments, and various modifications and changes are possible within the scope of the gist of the present invention. For example, all or part of the device can be configured by functionally or physically distributing or integrating any unit. Furthermore, new embodiments resulting from any combination of multiple embodiments are also included in the embodiments of the present invention. The effects of the new embodiments resulting from the combination also have the effects of the original embodiments. [Explanation of symbols]

[0043] 10 Internal combustion engine 11 Combustion chamber 14 Cylinder head 14a Bottom side 16a Intake valve 18 Injection part 50 recess 60 recess 62 Wide section 64 Communication part

Claims

1. A cylinder head covering the combustion chamber; an injection portion that protrudes from a lower surface of the cylinder head and injects fuel; an intake valve for supplying intake air to the combustion chamber; Equipped with the cylinder head has a recess provided in the lower surface along a circumferential direction around the injection portion, the recess is located on the lower surface between the injection portion and the intake valve, The recess is provided on the lower surface over the entire circumference in the circumferential direction.

2. The radial length of the recess is greater than the depth of the recess.

2. The internal combustion engine according to claim 1.

3. The depth of the recess is greater than the distance from the lower surface to the tip of the ejection portion.

2. The internal combustion engine according to claim 1.

4. The radial length of the recess is greater than the diameter of the injection portion.

2. The internal combustion engine according to claim 1.

5. A cylinder head covering the combustion chamber; an injection portion that protrudes from a lower surface of the cylinder head and injects fuel; Equipped with the cylinder head has a recess provided in the lower surface along a circumferential direction around the injection portion, a radial length of a facing portion of the recess facing a region through which the fuel injected from the injection portion passes is greater than a radial length of a portion of the recess other than the facing portion; Internal combustion engine.

6. The facing portions are provided at predetermined intervals in the circumferential direction of the recess.

6. An internal combustion engine according to claim 5.

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