Internal combustion engine

Abstract

To suppress a crack on a heat protector caused by a thermal deformation of an exhaust manifold.SOLUTION: An internal combustion engine 1 includes: a cylinder block 12 in which a plurality of cylinders is formed in a line in x direction; a cylinder head 14 provided above the cylinder block; an exhaust manifold 20 fixed to a side face 14a facing a vertical direction and a second direction orthogonal with the x direction of the cylinder head 14; and a heat protector 30 covering a top face of the exhaust manifold and fixed to the exhaust manifold by a first fixing part 32 and a second fixing part 34 which are apart from each other in the x direction. The heat protector includes a body facing the vertical direction. An intermediate end part 36 between the first fixing part 32 and the second fixing part at an end part on an opposite side of the cylinder head in a direction orthogonal with the x direction of the body is curved in the x direction several times.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Patent Document 1 listed below discloses a configuration in which a heat protector is fixed to an exhaust manifold to prevent heat generated in the exhaust manifold through which exhaust gas flows from being transferred to a cylinder head cover. The heat protector is divided into two parts to prevent cracks from occurring when the exhaust manifold is thermally deformed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-123950 Summary of the Invention [Problem to be solved by the invention]

[0004] It is known that cracks in heat protectors are caused by thermal deformation of the exhaust manifold. For example, when multiple cylinders are arranged in a row, the exhaust manifold is installed across the multiple cylinders. When such a heat protector is thermally deformed, it expands or contracts in the direction in which the multiple cylinders are arranged, causing cracks in the heat protector. However, the heat protector configuration divided into two parts as described above is insufficient to prevent cracks from occurring in the heat protector.

[0005] The present invention has been made in view of these points, and has an object to suppress cracks that occur in a heat protector due to thermal deformation of an exhaust manifold. [Means for solving the problem]

[0006] One aspect of the present invention provides an internal combustion engine comprising: a cylinder block in which a plurality of cylinders are formed in a row in a first direction; a cylinder head provided on top of the cylinder block; an exhaust manifold fixed to a side of the cylinder head facing a vertical direction and a second direction perpendicular to the first direction; and a heat protector covering an upper surface of the exhaust manifold and fixed to the exhaust manifold by a first fixing portion and a second fixing portion that are spaced apart in the first direction, wherein the heat protector has a main body portion facing the vertical direction, and an intermediate end portion of the main body portion at an end opposite the cylinder head in the second direction, which is between the first fixing portion and the second fixing portion, is bent multiple times in the first direction.

[0007] The intermediate end portion may have a plurality of bent portions, and the plurality of bent portions may be continuously connected in the first direction.

[0008] The bent portion may have a shape having projections and depressions in the up-down direction, and may have a wavy shape when viewed from the second direction.

[0009] The intermediate end portion may be curved in the vertical direction.

[0010] The first fixing portion and the second fixing portion may be fastened together with the exhaust manifold to the side surface of the cylinder head by a fastening member.

[0011] The intermediate end portion may be spaced apart from the exhaust manifold. The intermediate end portion may extend along the first direction when the exhaust manifold thermally expands.

[0012] The first fixing portion may be provided at one end of the heat protector in the first direction, and the second fixing portion may be provided at the other end of the heat protector in the first direction. [Effects of the Invention]

[0013] According to the present invention, it is possible to suppress cracks that occur in the heat protector due to thermal deformation of the exhaust manifold. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a schematic diagram showing a schematic configuration of an internal combustion engine 1 according to one embodiment. [Figure 2] FIG. 2 is a perspective view showing a heat protector 30. [Figure 3] 10 is a schematic diagram for explaining the direction in which the exhaust manifold 20 and the intermediate end portion 36 extend during thermal expansion. [Figure 4] FIG. 2 is a plan view of the heat protector 30 as viewed from above. DETAILED DESCRIPTION OF THE INVENTION

[0015] <Configuration of an internal combustion engine> Fig. 1 is a schematic diagram showing the general configuration of an internal combustion engine 1 according to one embodiment. For ease of explanation, Fig. 1 shows the configuration of the upper part of the internal combustion engine 1 as seen from the side. Furthermore, Fig. 1 does not show an exhaust passage connected to an exhaust manifold 20.

[0016] The internal combustion engine 1 is, for example, a diesel engine. The internal combustion engine 1 burns and expands a mixture of intake air and fuel in a combustion chamber to generate power. Here, the internal combustion engine 1 is mounted on a vehicle such as a truck, but is not limited to this and may also be mounted on a ship, for example.

[0017] 1, the internal combustion engine 1 has a cylinder block 12, a cylinder head 14, a head cover 16, an exhaust manifold 20, and heat protectors 30 and 40. The internal combustion engine 10 also has an intake manifold fixed to the cylinder head 14, but a description thereof will be omitted here.

[0018] The cylinder block 12 is a container that houses the pistons and crankshaft of the internal combustion engine 1. A plurality of cylinders are formed inside the cylinder block 12 so that a plurality of pistons can reciprocate. In the cylinder block 12, the plurality of cylinders are formed in a row in the x direction.

[0019] The cylinder head 14 is provided on top of the cylinder block 12. The cylinder head 14, together with the pistons inside the cylinder block 12, forms the combustion chambers of each cylinder. The cylinder head 14 is provided with an intake port that introduces intake air from the intake manifold into the combustion chamber, and an exhaust port that guides exhaust air from the combustion chamber to the exhaust manifold 20. Although not shown in FIG. 1 , the intake port, combustion chamber, and exhaust port are arranged in this order along the vertical direction and the y direction (second direction) perpendicular to the x direction (first direction). An intake valve is provided between the intake port and the combustion chamber, and opens and closes as needed in accordance with the engine's combustion cycle. Similarly, an exhaust valve is provided between the combustion chamber and the exhaust port, and opens and closes as needed in accordance with the engine's combustion cycle. The cylinder head 14 has a side surface 14a facing the y direction.

[0020] The head cover 16 covers the upper surface of the cylinder head 14. Specifically, the head cover 16 covers the valve mechanism (the mechanism that opens and closes the intake valves and exhaust valves) inside the cylinder head 14. The head cover 16 has the function of reducing the operating noise of the pistons and the combustion noise in the combustion chamber. Unlike the cylinder head 14, which is made of metal, the head cover 16 is made of resin.

[0021] A rubber packing is provided between the head cover 16 and the cylinder head 14. By providing the packing, the joining surfaces of the head cover 16 and the cylinder head 14 can be kept airtight.

[0022] The exhaust manifold 20 is a collecting pipe that collects exhaust gases discharged from the combustion chambers of each cylinder of the internal combustion engine 1. One end of the exhaust manifold 20 in the y direction is connected to an exhaust port of the cylinder head 14, and the other end in the y direction is connected to an exhaust passage. Exhaust gas discharged from the combustion chamber of each cylinder passes through the exhaust port and the exhaust manifold 20, flows into the exhaust passage, and is released into the atmosphere. The exhaust manifold 20 is fixed to a side surface 14a of the cylinder head 14 facing the y direction. Specifically, the exhaust manifold 20 is fixed to the side surface 14a of the cylinder head 14 by fastening members (bolts and nuts) 25. The exhaust manifold 20 is also connected to the exhaust passage by a connecting portion 21.

[0023] The exhaust passage is provided with a DPD (Diesel Particulate Diffuser) 26. The DPD 26 purifies the exhaust gas by capturing and burning PM (Particulate Matter) in the exhaust gas. The DPD 26 is disposed adjacent to the exhaust manifold 20 and the heat protector 30 in the y direction.

[0024] The heat protectors 30, 40 are provided to cover the exhaust manifold 20. Specifically, the heat protectors 30, 40 cover the upper surface of the exhaust manifold 20. The heat protector 30 covers the upper surface of the exhaust manifold 20 from one end of the exhaust manifold 20 in the x direction to the connecting portion 21. The heat protector 40 covers the upper surface of the exhaust manifold 20 from the other end of the exhaust manifold 20 in the x direction to the connecting portion 21. The heat protector 30 is fixed to the side surface 14a of the cylinder head 14 together with the exhaust manifold 20 by two fastening members 27. Similarly, the heat protector 40 is fixed to the side surface 14a of the cylinder head 14 together with the exhaust manifold 20 by two fastening members 27.

[0025] The heat protectors 30, 40 have the function of suppressing the transfer of heat from the exhaust gas flowing through the exhaust manifold 20 to the head cover 16. In particular, a rubber packing is provided between the head cover 16 and the cylinder head 14, and the heat protectors 30, 40 suppress the transfer of heat to the packing, which would cause the packing to deform.

[0026] Furthermore, the heat protector 30 has a function of suppressing the transfer of heat generated in the DPD 26 to the head cover 16. In the internal combustion engine 1, the DPD 26, which combusts PM in the exhaust gas, is provided adjacent to the exhaust manifold 20 and the head cover 16. The heat protector 30 is positioned between the DPD 26 and the head cover 16. As a result, the heat protector 30 suppresses the transfer of heat generated in the DPD 26 to the head cover 16.

[0027] The exhaust manifold 20 deforms, i.e., expands or contracts, depending on the temperature of the exhaust gas flowing inside. For example, when the temperature of the exhaust gas increases, the exhaust manifold 20 thermally expands. If the heat protectors 30, 40 are fixed to the exhaust manifold 20 at multiple fixing points and are unable to deform appropriately between the fixing points, cracks may occur in the heat protectors 30, 40 as the exhaust manifold 20 thermally expands. In contrast, the heat protectors 30, 40 of this embodiment, as will be described in detail later, employ a structure that makes it easier to tolerate deformation when the exhaust manifold 20 is thermally deformed, thereby making it possible to suppress cracks from occurring in the heat protectors 30, 40.

[0028] <Detailed configuration of heat protector> The detailed configuration of the heat protector 30 will be described below with reference to FIGS.

[0029] FIG. 2 is a perspective view showing the heat protector 30. As shown in FIG. The heat protector 30 has an L-shape as shown in Fig. 2. That is, the heat protector 30 has a shape that extends long in the x direction, and the portion corresponding to the end of the exhaust manifold 20 in the x direction has a shape that extends in the vertical direction so as to cover the exhaust manifold 20. The heat protector 30 is fixed to the exhaust manifold 20 at both end portions in the x direction. As shown in Fig. 2, the heat protector 30 has a first fixing portion 32, a second fixing portion 34, an intermediate end portion 36, and an upright portion 50.

[0030] As shown in FIG. 1 , the first fixing portion 32 is a fixing portion that fixes the heat protector 30 to the exhaust manifold 20. In other words, the heat protector 30 is fixed to the exhaust manifold 20 at the first fixing portion 32. Specifically, the heat protector 30 is fixed together with the exhaust manifold 20 to the side surface 14a of the cylinder head 14 at the first fixing portion 32 by a fastening member 27. More specifically, the first fixing portion 32 has a hole 32a through which a bolt of the fastening member 27 is inserted, and an insertion hole formed in the exhaust manifold 20 and the hole 32a in the heat protector 30 communicate with each other and are fastened by the single fastening member 27. In other words, at the first fixing portion 32, the heat protector 30 is fastened together with the fastening member 27. This eliminates the need for a dedicated fastening member for fixing the first fixing portion 32 to the cylinder head 14, thereby reducing the number of parts.

[0031] 2, the first fixing portion 32 is provided at one end portion in the x direction of the main body portion 31 of the heat protector 30. Here, the main body portion 31 is a portion of the heat protector 30 facing in the up and down direction. Note that the first fixing portion 32 may be located closer to the center of the heat protector 30 than the one end portion.

[0032] The second fixing portion 34 is a fixing portion that fixes the heat protector 30 to the exhaust manifold 20, as shown in FIG. 1 . In other words, the heat protector 30 is fixed to the exhaust manifold 20 by the first fixing portion 32 and the second fixing portion 34. Specifically, the heat protector 30 is fixed together with the exhaust manifold 20 to the side surface 14a of the cylinder head 14 at the second fixing portion 34 by a fastening member 27. More specifically, the second fixing portion 34 has a hole 34a through which a bolt of the fastening member 27 is inserted, and an insertion hole formed in the exhaust manifold 20 and the hole 34a in the heat protector 30 communicate with each other and are fastened together by the single fastening member 27. In other words, the second fixing portion 34 is fastened together by the fastening member 27.

[0033] The first fixing portion 32 and the second fixing portion 34 are provided at positions spaced apart in the x direction. Specifically, as shown in Fig. 2, the second fixing portion 34 is provided at the other end in the x direction of the main body portion 31 of the heat protector 30. Note that the second fixing portion 34 may be located closer to the center of the heat protector 30 than the other end.

[0034] As shown in FIG. 2 , the intermediate end 36 is a portion between the first fixing portion 32 and the second fixing portion 34 at the end of the main body 31 of the heat protector 30 opposite the cylinder head 14 in the y direction. The intermediate end 36 is not straight in the x direction, but is bent multiple times in the x direction. Specifically, the intermediate end 36 is bent in the up-down direction. By bending the intermediate end 36 in this way, when the heat protector 30 deforms in the x direction together with the exhaust manifold 20, the intermediate end 36 is more likely to tolerate deformation. As a result, when the exhaust manifold 20 thermally deforms, the intermediate end 36 also deforms accordingly, which makes it possible to prevent cracks from occurring in the intermediate end 36.

[0035] FIG. 3 is a schematic diagram illustrating the direction in which the exhaust manifold 20 and the intermediate end portion 36 extend during thermal expansion. When the temperature of the exhaust gas flowing through the exhaust manifold 20 increases, the exhaust manifold 20 thermally expands. Specifically, the exhaust manifold 20 extends in the x direction (the direction of arrow A1 shown in FIG. 3 ). The intermediate end portion 36 of the heat protector 30, which is fixed to the exhaust manifold 20 by the first fixing portion 32 and the second fixing portion 34, also extends in the x direction (the direction of arrow A2). Because the intermediate end portion 36 has a shape that is bent multiple times, the intermediate end portion 36 extends along the x direction when the exhaust manifold 20 thermally expands. In other words, when the exhaust manifold 20 thermally deforms, the intermediate end portion 36 also deforms accordingly. In this way, the intermediate end portion 36 can tolerate deformation in the x direction when the exhaust manifold 20 thermally deforms. Therefore, cracks are less likely to occur in the intermediate end portion 36 when the exhaust manifold 20 thermally deforms. On the other hand, unlike the present embodiment, if the intermediate end 36 is straight instead of being bent multiple times, the intermediate end 36 will not easily stretch in the x direction, and will therefore not be able to tolerate deformation in the x direction, resulting in breakage when stretched (in other words, cracks will occur in the intermediate end 36).

[0036] As shown in FIG. 2, the intermediate end 36 has a plurality of bent portions 37. The bent portions 37 are formed so as to be uneven in the vertical direction. The bent portions 37 are also continuously connected in the x direction. In other words, the shape of the intermediate end 36 when viewed from the y direction is undulating. As a result, when the exhaust manifold 20 is thermally deformed, the bent portions 37 deform so as to extend in the x direction, effectively suppressing the occurrence of cracks. Furthermore, stress generated inside the intermediate end 36 is more easily dispersed, more effectively suppressing the occurrence of cracks.

[0037] 1, the intermediate end portion 36 is spaced apart from the exhaust manifold 20. This makes it possible to prevent external force from being applied to the intermediate end portion 36 from the exhaust manifold 20 when the exhaust manifold 20 thermally expands.

[0038] The standing plate portion 50 is provided on the main body portion 31 as shown in FIG. 2. The standing plate portion 50 is located between the head cover 16 and the DPD 26. The standing plate portion 50 prevents heat generated in the DPD 26 from being transferred to the head cover 16. FIG. 4 shows a plan view of the heat protector 30 as viewed from above. The standing plate portion 50 is fixed to the main body portion 31 at a joint portion 51 shown in FIG. 4. The standing plate portion 50 is joined to the main body portion 31 at the joint portion 51 with, for example, a rivet.

[0039] 1 has a first fixing portion 42, a second fixing portion 44, and an intermediate end portion 46, which have the same configuration as the first fixing portion 32, the second fixing portion 34, and the intermediate end portion 36 of the heat protector 30. Therefore, the intermediate end portion 46 of the heat protector 40 also deforms in the x direction when the exhaust manifold 20 thermally expands, thereby suppressing the occurrence of cracks in the intermediate end portion 46.

[0040] In this case, the heat protector 40 does not have the standing plate portion 50 because the DPD 26 is not adjacent to it. However, the present invention is not limited to this, and if the DPD 26 is adjacent to the heat protector 40, the heat protector 40 may also have the standing plate portion 50. In this case, it is possible to suppress the heat generated by the DPD 26 from being transferred to the head cover 16.

[0041] <Effects of this embodiment> The internal combustion engine 1 of the above-described embodiment has a heat protector 30 that covers the exhaust manifold 20 and is fixed to the exhaust manifold 20 at a first fixing portion 32 and a second fixing portion 34 in the x direction. An intermediate end portion 36 of the heat protector 30 between the first fixing portion 32 and the second fixing portion 34 is bent multiple times in the x direction. The bending of the intermediate end portion 36 in this manner makes it easier to tolerate deformation in the x direction of the heat protector 30. As a result, even if the exhaust manifold 20 is thermally deformed in the x direction, the intermediate end portion 36 deforms in the x direction accordingly, thereby preventing cracks from occurring in the intermediate end portion 36.

[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] 1. Internal combustion engine 14 Cylinder head 16 Headcover 20 Exhaust manifold 30 Heat protector 32 1st fixed part 34 Second fixed part 36 Middle end 37 Bending section

Claims

1. a cylinder block in which a plurality of cylinders are formed in a row in a first direction; a cylinder head provided on an upper portion of the cylinder block; an exhaust manifold fixed to a side surface of the cylinder head facing a second direction perpendicular to the up-down direction and the first direction; a heat protector that covers an upper surface of the exhaust manifold and is fixed to the exhaust manifold by a first fixing portion and a second fixing portion that are spaced apart in the first direction; Equipped with the heat protector has a main body portion facing in the vertical direction, an intermediate end portion of the main body portion, which is a portion between the first fixing portion and the second fixing portion at an end portion opposite the cylinder head in the second direction, is bent a plurality of times in the first direction; Internal combustion engine.

2. the intermediate end portion has a plurality of bends; the plurality of bent portions are continuously connected in the first direction; 2. The internal combustion engine according to claim 1.

3. The bent portion has a shape having projections and depressions in the up-down direction, and a shape thereof when viewed from the second direction is a wavy shape.

3. The internal combustion engine according to claim 2.

4. The intermediate end portion is bent in the vertical direction.

2. The internal combustion engine according to claim 1.

5. the first fixing portion and the second fixing portion are fastened together with the exhaust manifold to the side surface of the cylinder head by fastening members; 2. The internal combustion engine according to claim 1.

6. The intermediate end is spaced from the exhaust manifold.

2. The internal combustion engine according to claim 1.

7. The intermediate end portion extends along the first direction when the exhaust manifold thermally expands.

2. The internal combustion engine according to claim 1.

8. the first fixing portion is provided at one end of the heat protector in the first direction, the second fixing portion is provided at the other end of the heat protector in the first direction; 2. The internal combustion engine according to claim 1.

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