Internal combustion engine

Abstract

To promote the vaporization of fuel mixed in oil using a simple configuration. [Solution] The internal combustion engine 10 comprises a combustion chamber 20 in which fuel is burned, a cylinder block 11 having cylinders that partition the combustion chamber 20, a cylinder head 12 fixed to the cylinder block 11 and having an exhaust port 22, an exhaust manifold 28 forming an exhaust passage 31 connected to the exhaust port 22, a manifold internal passage 34 formed around the exhaust passage 31 in the exhaust manifold 28, an oil pan 15 that communicates with the cylinder 16 and stores oil, an oil supply passage 32 that supplies oil stored in the oil pan 15 to the inside of the cylinder head 12, and an oil return passage 35 that returns the oil inside the cylinder head 12 to the oil pan 15. A part of the manifold internal passage 34 is isolated as part of the oil return passage 35.

Description

Technical Field

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

Background Art

[0002] For example, as disclosed in Patent Document 1, an internal combustion engine includes a combustion chamber, a cylinder block, a cylinder head, an exhaust manifold, an oil pan, an oil supply passage, and an oil return passage. In the combustion chamber, fuel burns. The cylinder block has cylinders. The cylinders partition the combustion chamber. The cylinder head is fixed to the cylinder block. The cylinder head has an exhaust port. The exhaust manifold forms an exhaust passage. The exhaust passage is connected to the exhaust port. The oil pan communicates with the cylinders. The oil pan stores oil. The oil supply passage supplies the oil stored in the oil pan to the inside of the cylinder head. Thereby, the sliding parts existing inside the cylinder head are lubricated by the oil. The oil return passage returns the oil inside the cylinder head to the oil pan.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in an internal combustion engine, if the fuel adhering to the inside of the cylinder mixes into the oil stored in the oil pan, the oil will be diluted. When the oil is diluted, the viscosity of the oil decreases, resulting in a decrease in the lubricity of the sliding parts. Therefore, it is necessary to promote the volatilization of the fuel mixed into the oil by heating the oil mixed with the fuel.

Means for Solving the Problems

[0005] An internal combustion engine that solves the above problems comprises a combustion chamber in which fuel is burned, a cylinder block having cylinders that partition the combustion chamber, a cylinder head fixed to the cylinder block and having an exhaust port, an exhaust manifold forming an exhaust passage connected to the exhaust port, a manifold internal passage formed around the exhaust passage in the exhaust manifold, an oil pan that communicates with the cylinders and stores oil, an oil supply passage that supplies oil stored in the oil pan into the inside of the cylinder head, and an oil return passage that returns the oil inside the cylinder head to the oil pan, wherein a part of the manifold internal passage is isolated as part of the oil return passage.

[0006] According to the above configuration, the oil supply passage supplies oil stored in the oil pan to the inside of the cylinder head. This lubricates the sliding parts inside the cylinder head with oil. The oil return passage then returns the oil from inside the cylinder head to the oil pan. In addition, the flow of cooling fluid through the manifold passage cools the area around the exhaust passage in the exhaust manifold. Therefore, the heat of the exhaust flowing through the exhaust passage is dissipated to the area around the exhaust passage in the exhaust manifold. As a result, the exhaust flowing through the exhaust passage is cooled. This configuration, in which the manifold passage functions as a cooling fluid passage through which cooling fluid flows to cool the exhaust, is an existing configuration. Therefore, the configuration in which a manifold passage is formed in the exhaust manifold is an existing configuration. So, a part of the existing manifold passage was isolated as part of the oil return passage. With this, the oil flowing through the oil return passage can be warmed by the heat of the exhaust flowing through the exhaust passage. Therefore, even if fuel adhering to the cylinder mixes with the oil stored in the oil pan, the oil containing the fuel can be heated with a simple configuration. Thus, the vaporization of the fuel mixed in the oil can be promoted with a simple configuration. [Effects of the Invention]

[0007] According to this invention, the vaporization of fuel mixed in oil can be promoted with a simple configuration. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a cross-sectional view illustrating an internal combustion engine. [Modes for carrying out the invention]

[0009] Below, one embodiment of the internal combustion engine will be described with reference to Figure 1. As shown in Figure 1, the internal combustion engine 10 comprises a cylinder block 11, a cylinder head 12, a cylinder head cover 13, a crankcase 14, and an oil pan 15. The cylinder head 12 is fixed to the upper part of the cylinder block 11. The cylinder head cover 13 is attached to the upper part of the cylinder head 12. The crankcase 14 is located at the lower part of the cylinder block 11. The oil pan 15 is attached to the lower part of the crankcase 14.

[0010] The cylinder block 11 has cylinders 16. The internal combustion engine 10 includes pistons 17. The pistons 17 are reciprocally housed within the cylinders 16. The internal combustion engine 10 includes a crankshaft 18. The crankshaft 18 is supported by the crankcase 14. The crankshaft 18 is connected to the pistons 17 via connecting rods 19.

[0011] The internal combustion engine 10 is equipped with a combustion chamber 20. The combustion chamber 20 is a space enclosed by the top surface of the piston 17, the wall surface of the cylinder head 12, and the wall surface of the cylinder 16. Thus, the cylinder 16 partitions the combustion chamber 20. Fuel burns in the combustion chamber 20.

[0012] The cylinder head 12 has an intake port 21 and an exhaust port 22. The internal combustion engine 10 is equipped with an intake valve 23 and an exhaust valve 24. The intake valve 23 and the exhaust valve 24 are provided in the cylinder head 12. The intake valve 23 can open and close the intake port 21. The exhaust valve 24 can open and close the exhaust port 22. The internal combustion engine 10 is equipped with a first camshaft 25 and a second camshaft 26. The first camshaft 25 and the second camshaft 26 are rotatably mounted relative to the cylinder head 12. The first camshaft 25 drives the intake valve 23. The second camshaft 26 drives the exhaust valve 24.

[0013] The internal combustion engine 10 includes an intake manifold 27 and an exhaust manifold 28. The intake manifold 27 and the exhaust manifold 28 are integrally formed with the cylinder head 12. Thus, the intake manifold 27 and the exhaust manifold 28 are integrated with the cylinder head 12. The intake manifold 27 forms an intake passage 29 connected to an intake port 21. A throttle valve 30 is provided in the intake passage 29. The throttle valve 30 adjusts the amount of intake air flowing through the intake passage 29. The exhaust manifold 28 forms an exhaust passage 31 connected to an exhaust port 22.

[0014] The oil pan 15 is in communication with the cylinder 16. The oil pan 15 stores oil. The internal combustion engine 10 is equipped with an oil supply passage 32. The oil supply passage 32 penetrates the cylinder block 11 and the cylinder head 12. The first end of the oil supply passage 32 opens to the lower part of the cylinder block 11. The second end of the oil supply passage 32 opens to the upper part of the cylinder head 12. The internal combustion engine 10 is equipped with an oil pump 33. The oil pump 33 pumps the oil stored in the oil pan 15 into the oil supply passage 32. The oil supply passage 32 supplies the oil pumped from the oil pump 33 into the interior of the cylinder head 12. In this way, the oil supply passage 32 supplies the oil stored in the oil pan 15 into the interior of the cylinder head 12. The oil that has flowed through the oil supply passage 32 flows out into the space inside the cylinder head cover 13.

[0015] The internal combustion engine 10 is equipped with a manifold passage 34. The manifold passage 34 is formed around the exhaust passage 31 in the exhaust manifold 28. Cooling water, which is a cooling fluid, flows through a portion of the manifold passage 34. Therefore, a portion of the manifold passage 34 functions as a cooling fluid passage.

[0016] The internal combustion engine 10 is equipped with an oil return passage 35. The oil return passage 35 has a first passage 36, a second passage 37, a third passage 38, and a fourth passage 39. The first passage 36 is formed in the cylinder head 12. The first end of the first passage 36 opens to the top of the cylinder head 12. The second end of the first passage 36 is located inside the cylinder head 12. The second passage 37 is formed in the cylinder head 12 and the exhaust manifold 28. The first end of the second passage 37 is connected to the second end of the first passage 36. The second end of the second passage 37 is connected to a part of the manifold internal passage 34. The third passage 38 is formed in the exhaust manifold 28, the cylinder head 12, and the cylinder block 11. The first end of the third passage 38 is connected to a part of the manifold internal passage 34. The second end of the third passage 38 is located inside the cylinder block 11. The fourth passage 39 is formed in the cylinder block 11. The first end of the fourth channel 39 is connected to the second end of the third channel 38. The second end of the fourth channel 39 opens into the lower part of the cylinder block 11.

[0017] The oil in the cylinder head cover 13 is then returned to the oil pan 15 via the first passage 36, the second passage 37, a portion of the manifold passage 34, the third passage 38, and the fourth passage 39. In this way, the oil return passage 35 returns the oil from inside the cylinder head 12 to the oil pan 15. Therefore, a portion of the manifold passage 34 is isolated as part of the oil return passage 35. The manifold passage 34 that is part of the oil return passage 35 is isolated from the manifold passage 34 that functions as a cooling fluid passage.

[0018] The oil supply passage 32 supplies oil stored in the oil pan 15 to the inside of the cylinder head 12. This lubricates the sliding parts inside the cylinder head 12, such as the first camshaft 25 and the second camshaft 26. The oil return passage 35 then returns the oil from inside the cylinder head 12 to the oil pan 15.

[0019] When cooling water flows through the manifold internal flow path 34, the periphery of the exhaust passage 31 in the exhaust manifold 28 is cooled by the cooling water. Therefore, the heat of the exhaust flowing through the exhaust passage 31 is radiated to the periphery of the exhaust passage 31 in the exhaust manifold 28. As a result, the exhaust flowing through the exhaust passage 31 is cooled.

[0020] By the way, in the internal combustion engine 10, the fuel adhering to the inside of the cylinder 16 may be mixed into the oil stored in the oil pan 15. Here, the oil flowing through the second flow path 37 of the oil return flow path 35 is guided to a part of the manifold internal flow path 34. The oil guided to a part of the manifold internal flow path 34 is warmed by the heat of the exhaust flowing through the exhaust passage 31. Therefore, even if the fuel adhering to the inside of the cylinder 16 is mixed into the oil stored in the oil pan 15, the oil mixed with the fuel is heated. Thereby, the volatilization of the fuel mixed into the oil is promoted.

[0021] <Effects of the present embodiment> In the present embodiment, the following effects can be obtained. (1) The configuration that makes the manifold internal flow path 34 function as a cooling fluid flow path through which cooling water for cooling the exhaust flows is an existing configuration. Therefore, the configuration in which the manifold internal flow path 34 is formed in the exhaust manifold 28 is an existing configuration. Then, a part of the manifold internal flow path 34, which is an existing configuration, is isolated as a part of the oil return flow path 35. According to this, the oil flowing through the oil return flow path 35 can be warmed by the heat of the exhaust flowing through the exhaust passage 31. Therefore, even if the fuel adhering to the inside of the cylinder 16 is mixed into the oil stored in the oil pan 15, the oil mixed with the fuel can be heated with a simple configuration. Thus, the volatilization of the fuel mixed into the oil can be promoted with a simple configuration.

Explanation of reference numerals

[0022] 10...Internal combustion engine, 11...Cylinder block, 12...Cylinder head, 15...Oil pan, 16...Cylinder, 20...Combustion chamber, 22...Exhaust port, 28...Exhaust manifold, 31...Exhaust passage, 32...Oil supply passage, 34...Manifold internal passage, 35...Oil return passage.

Claims

[Claim 1] The combustion chamber where the fuel burns, A cylinder block having cylinders that partition the combustion chamber, A cylinder head fixed to the cylinder block and having an exhaust port, An exhaust manifold forming an exhaust passage connected to the exhaust port, A manifold internal flow path formed around the exhaust passage in the exhaust manifold, An oil pan that communicates with the aforementioned cylinder and stores oil, An oil supply passage for supplying oil stored in the oil pan to the inside of the cylinder head, An internal combustion engine comprising an oil return passage for returning oil inside the cylinder head to the oil pan, An internal combustion engine characterized in that a portion of the flow path within the manifold is isolated as part of the oil return flow path.

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