Internal combustion engine

Abstract

To provide an internal combustion engine that can suppress damage to the supercharger. [Solution] The internal combustion engine comprises an internal combustion engine body, a supercharger connected to the internal combustion engine body, and an intake device connected to the internal combustion engine body. The intake device has a first passage for introducing fresh air into the supercharger and a second passage through which blow-by gas flows from the internal combustion engine body. The second passage extends adjacent to the first passage and, at one end, merges with the first passage from diagonally behind in the direction of the fresh air flow. A space is provided inside the partition wall separating the adjacent first and second passages.

Description

Technical Field

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

Background Art

[0002] Regarding an internal combustion engine, for example, Patent Document 1 describes introducing blow-by gas into an intake passage connected to a supercharger via an introduction passage.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When blow-by gas flows from the introduction passage into the intake passage, it is rapidly cooled by the cold fresh air flowing in the intake passage, so moisture in the blow-by gas crystallizes to generate a large number of ice crystals. The ice crystals may flow into the downstream supercharger and damage the impeller or the like.

[0005] Therefore, the present invention has been made in view of the above problems, and an object thereof is to provide an internal combustion engine capable of suppressing damage to the supercharger.

Means for Solving the Problems

[0006] The internal combustion engine of the present invention includes an internal combustion engine body, a supercharger connected to the internal combustion engine body, and an intake device connected to the internal combustion engine body. The intake device has a first flow path for introducing fresh air into the supercharger and a second flow path through which blow-by gas flows from the internal combustion engine body. The second flow path extends adjacent to the first flow path and, at one end, merges with the first flow path obliquely rearward in the direction of flow of the fresh air. A space is provided inside a partition wall separating the adjacent first flow path and second flow path.

[0007] In the internal combustion engine described above, the partition wall may have a curved surface at one end that bulges out toward the second flow path and curves toward the first flow path.

[0008] In the internal combustion engine described above, the second passage has a connection portion that is connected to the blow-by gas vent provided in the head cover of the internal combustion engine, and the connection portion may have an orifice.

[0009] The above-described internal combustion engine may have an insulating material provided in the space.

[0010] The above-described internal combustion engine may have a heating means provided in the space for heating the second flow path. [Effects of the Invention]

[0011] According to the present invention, damage to the supercharger of an internal combustion engine can be suppressed. [Brief explanation of the drawing]

[0012] [Figure 1] Figure 1 is a diagram illustrating the schematic configuration of the engine. [Figure 2] Figure 2 is a perspective view illustrating an intake duct attached to the cylinder head cover. [Figure 3] Figure 3 illustrates a cross-section of the intake duct along line AA in Figure 2. [Figure 4] Figure 4 illustrates a cross-section of the intake duct along line BB in Figure 3. [Figure 5] Figure 5(A) illustrates a cross-section of an intake duct in which insulation material is provided in the space within the partition wall. Figure 5(B) illustrates a cross-section of an intake duct in which heating means are provided in the space within the partition wall. [Modes for carrying out the invention]

[0013] (Overall engine configuration) Figure 1 is a diagram illustrating the schematic configuration of engine 10. Engine 10 is a spark-ignition type 4-cylinder gasoline engine, which is an example of an internal combustion engine, but is not limited to this. It may also be a type of engine other than a 4-cylinder engine, such as a compression-ignition type diesel engine.

[0014] The engine 10 comprises an internal combustion engine body 11, a head cover 12, a crankcase 13, a piston 14, a combustion chamber 15, an intake passage 16, a supercharger 20, an intercooler 22, and a throttle valve 24. The internal combustion engine body 11 has a cylinder 11a, a head cover 12 located above the cylinder 11a, and a crankcase 13 located below the cylinder 11a. The piston 14 reciprocates within the combustion chamber 15 of the cylinder 11a. Each cylinder of the internal combustion engine body 11 is connected to an intake passage 16 via an intake manifold 16a.

[0015] The air cleaner 17 is mounted near the inlet of the intake passage 16. The compressor 20a of the supercharger 20 is located downstream of the air cleaner 17 in the intake passage 16 and compresses the intake air. The compressor 20a is integrally connected to the turbine 20b located in the exhaust passage via a connecting shaft.

[0016] The intercooler 22 is installed downstream of the compressor 20a in the intake passage 16 and cools the supercharged air. The electronically controlled throttle valve 24 is located downstream of the intercooler 22. Downstream of the throttle valve 24 is the intake manifold 16a.

[0017] Inside the cylinder 11a and the head cover 12, a blow-by gas guide passage 31 is provided. This blow-by gas guide passage 31 is formed to penetrate through the cylinder 11a and the head cover 12, communicates the inside of the crankcase 13 with the main separator 43, and guides the blow-by gas existing in the crankcase 13 to the main separator 43. Further, a communication port 431 is provided in the main separator 43, which communicates the head cover 12 with the main separator 43, and guides the blow-by gas existing in the internal space of the head cover 12 to the main separator 43.

[0018] The blow-by gas is guided to the main separator 43 through the blow-by gas guide passage 31, and the blow-by gas from which the oil mist has been separated by the main separator 43 is refluxed to the intake manifold 16a through a blow-by gas recirculation passage 36 that communicates the main separator 43 with the intake manifold 16a.

[0019] A PCV (Positive Crankcase Ventilation) valve 38 is installed at the end of the blow-by gas recirculation passage 36 on the main separator 43 side. The PCV valve 38 is configured as a differential pressure operated valve that operates according to the differential pressure between the internal space of the head cover 12 on its upstream side and the intake manifold 16a on its downstream side. With such a PCV valve 38, the flow rate of the blow-by gas refluxing to the intake manifold 16a is adjusted, and the backflow of the blow-by gas into the internal space of the head cover 12 is prevented.

[0020] A fresh air introduction passage 34 is provided to communicate the internal space of the head cover 12 with the intake passage 16 on the upstream side of the compressor 20a and on the downstream side of the air cleaner 17. More specifically, the fresh air introduction passage 34 communicates the intake passage 16 with the atmospheric side separator 44. The atmospheric side separator 44 is provided in the head cover 12 and includes a first communication port 441 and a second communication port 442. The first communication port 441 communicates with the inside of the head cover 12. The second communication port 442 communicates with the fresh air introduction passage 34. Further, a fresh air guide passage 33 communicates the inside of the head cover 12 with the inside of the crankcase 13. Therefore, the fresh air passing through the intake passage 16 is introduced into the internal space of the head cover 12 and the crankcase 13 by the fresh air introduction passage 34, the atmospheric side separator 44, and the fresh air guide passage 33.

[0021] When the engine 10 is operating in a naturally aspirated state, the combustion chamber 15 and the intake manifold 16a on the downstream side of the throttle valve 24 are in a negative pressure state, and the intake passage 16 on the upstream side of the compressor 20a is at atmospheric pressure. For this reason, fresh air flows through the fresh air introduction passage 34, the atmospheric side separator 44, the head cover 12, the fresh air guide passage 33, and the crankcase 13. Also, the blow-by gas is returned from the crankcase 13 and the head cover 12 to the intake manifold 16a through the main separator 43 and the blow-by gas recirculation passage 36. In the main separator 43, the oil component is separated from the blow-by gas. In this way, the blow-by gas is supplied from the intake manifold 16a into the combustion chamber 15, and the blow-by gas can be burned.

[0022] When the engine 10 is operating in a supercharged state, the combustion chamber 15 and intake manifold 16a downstream of the compressor 20a are under positive pressure, while the intake passage 16 upstream of the compressor 20a is under negative pressure. As a result, blow-by gas flows sequentially from the crankcase 13 through the blow-by gas guide passage 31, main separator 43, head cover 12, atmospheric separator 44, and fresh air introduction passage 34, and then flows back into the intake passage 16 upstream of the compressor 20a. At the atmospheric separator 44, the oil component is separated from the blow-by gas. In this way, the blow-by gas is supplied into the combustion chamber 15 and can be burned.

[0023] In the above configuration, the intake passage 16 between the supercharger 20 and the air cleaner 17, and the confluence of the fresh air introduction passage 34, are realized by the intake duct 5. The intake duct 5 is an example of an intake system for an internal combustion engine. The intake duct 5 and the supercharger 20 are connected to the internal combustion engine body 11. The intake duct 5 will be described below.

[0024] (Intake duct configuration)

[0025] Figure 2 is a perspective view illustrating an intake duct 5 attached to the head cover 12. Note that in Figures 2 and subsequent figures, the X, Y, and Z directions, which are orthogonal to each other, are shown.

[0026] The head cover 12 is made of, for example, resin or aluminum, and is positioned on top of the cylinder 11a. The shapes of the head cover 12 and cylinder 11a are schematically represented as rectangular parallelepipeds. A connector portion 120, which connects to the intake duct 5, is provided near the corner of the head cover 12. The connector portion 120 corresponds to the end of the fresh air introduction passage 34 on the head cover 12 side. The connector portion 120 is an example of a blow-by gas vent.

[0027] The intake duct 5 is made of, for example, steel and has a connecting portion 50, a first piping portion 51, and a second piping portion 52. The connecting portion 50 extends in a direction perpendicular to the direction in which the first piping portion 51 and the second piping portion 52 extend. The connecting portion 50 is connected to a part of the side surface of the first piping portion 51 and one end of the second piping portion 52. The connecting portion 50 is inserted into the opening of the connector portion 120 of the head cover 12. This connects the fresh air introduction passage 34 inside the head cover 12 to the flow path inside the intake duct 5. A sealing member, such as an O-ring, is provided inside the connector portion 120 between it and the connecting portion 50.

[0028] The upstream side of the first piping section 51 is connected to the air cleaner 17, and the downstream side of the first piping section 51 is connected to the compressor 20a of the supercharger 20. The second piping section 52 is narrower than the first piping section 51 and is connected to the connection section 50 and the first piping section 51. Intake air flows through the first piping section 51 from the air cleaner 17 towards the compressor 20a. When the engine 10 is operating in supercharged mode, blow-by gas from the crankcase 13 flows through the connection section 50 and the second piping section 52 towards the first piping section 51.

[0029] In this manner, the intake duct 5 connects the head cover 12, the air cleaner 17, and the compressor 20a. If the connection point 50 between the head cover 12 and the intake duct 5 were connected via a hose, it would be necessary to install, for example, a pressure sensor to detect if the hose connection becomes disconnected, in accordance with legal regulations and other requirements. However, in this example, the connection point 50 of the intake duct 5 is directly inserted into the connector part 120 of the head cover 12 without using a hose, thus eliminating the need for a means to detect disconnection, such as a pressure sensor.

[0030] Figure 3 illustrates a cross-section of the intake duct 5 along line AA in Figure 2. Figure 4 illustrates a cross-section of the intake duct 5 along line BB in Figure 3. A first flow path 61 is provided inside the first piping section 51, and a second flow path 62 is provided inside the second piping section 52 and the connecting section 50. The second piping section 52 has an extension section 521 that extends parallel to the first piping section 51, and an end section 522 that curves from the extension section 521 toward the first piping section 51. The end section 522 is an example of one end of the second flow path 62. The cross-sectional area of ​​the first flow path 61 is larger than the cross-sectional area of ​​the second flow path 62. As an example, the cross-section of the first flow path 61 is approximately circular, and the cross-section of the second flow path 62 is approximately rectangular, but it is not limited to this, and other cross-sectional shapes may be used.

[0031] The opposite end of the extension portion 521 is connected to the connecting portion 50. The connecting portion 50 is bent perpendicular to the extension portion 521 (in the Y direction) and inserted into the connector portion 120. An orifice 53 is provided inside the connecting portion 50 to increase the pressure loss of blow-by gas. The orifice 53 is integrally formed with the connecting portion 50. When the engine 10 is operating in a naturally aspirated state, the orifice 53 acts to create negative pressure inside the engine 10.

[0032] In this configuration, the orifice 53 is located in the intake duct 5, rather than in the connector portion 120 of the head cover 12. Therefore, maintenance of the orifice 53 is easily performed by removing the intake duct 5 from the head cover 12. Note that, unlike this example, the orifice 53 may also be located within the connector portion 120.

[0033] The first passage 61 extends linearly in the X direction, and fresh air from the air cleaner 17 flows through the first passage 61 as indicated by symbol D1 and is introduced to the supercharger 20. The second passage 62 bends at approximately a right angle between the connection part 50 and the second piping part 52, extends linearly in the X direction within the second piping part 52, and bends obliquely with respect to the first passage 61 at its end 522. Blow-by gas from the head cover 12 flows as indicated by symbol D2 and merges with the fresh air in the first passage 61. Thus, the second passage 62 extends adjacent to the first passage 61 and merges with the first passage 61 at its end 522 from obliquely behind the direction in which the fresh air flows in the first passage 61. The cross-sectional area of ​​the first passage 61 is substantially constant on the upstream and downstream sides of the merging point with the second passage 62.

[0034] Furthermore, the first channel 61 and the second channel 62 are adjacent to each other in the Y direction. Inside the partition wall 54 separating the first channel 61 and the extended portion 521 of the second channel 62, a space 60 extending in the X direction is provided. Therefore, the first channel 61 and the second channel 62 are thermally isolated from each other by the space 60. Consequently, compared to the case where the space 60 does not exist, the rapid cooling of the blow-by gas in the extended portion 521 by the fresh air in the first channel 61 is suppressed, making it difficult for moisture in the blow-by gas to crystallize. Therefore, the formation of ice crystals P in the second channel 62 due to the cooling of the fresh air in the first channel 61 is suppressed. Note that the longer the length of the space 60 in the X direction, the less the blow-by gas is cooled, which is preferable.

[0035] Furthermore, even if moisture in the blow-by gas crystallizes and ice crystals P are formed, the second channel 62 merges with the first channel 61 at its end 522 from an oblique direction to the direction of fresh air flow. Therefore, many of the ice crystals P that enter the first channel 61 are easily carried downstream along with the fresh air. In contrast, if the blow-by gas were to merge directly into the first channel 61 from the connection 50 in a direction perpendicular to the direction of fresh air flow, then in the first channel 61, many ice crystals P would easily accumulate and grow on the wall surface 51a opposite the opening of the second channel 62, thus generating large ice crystals Ps.

[0036] However, in this example, since the second channel 62 merges with the first channel 61 in a direction inclined with respect to the flow of fresh air in the first channel 61, even if small ice crystals P are generated along with the fresh air, they are easily carried towards the compressor 20a side in accordance with the flow of fresh air in the first channel 61. Therefore, unlike the above case, ice crystals P are less likely to accumulate on the wall surface 51a of the first channel 61. As a result, the growth of numerous ice crystals P into large ice crystals Ps is suppressed, and consequently, damage to the compressor 20a is suppressed.

[0037] The angle θ at which the second channel 62 merges with the first channel 61 is defined in the cross-section of Figure 3 as the angle between the tangent line L passing through a reference point S on the inner wall 522a of the downstream end 522 of the second channel 62 and the wall surface 51a in the first channel 61. Here, the reference point S is, for example, the center position of the width of the second channel 62 in the Y direction. The above effect can be obtained if the angle θ is less than 90 degrees, but a smaller angle θ is preferable because it makes it more difficult for ice crystals P to reach the wall surface 51a of the first channel 61, and thus less likely for large ice crystals Ps to be generated.

[0038] Furthermore, at end 522, the downstream end 54a of the partition wall 54 has a curved surface E that bulges towards the second flow path 62 and curves towards the first flow path 61. Therefore, compared to the case where the downstream end 54a is a corner-shaped wall that curves perpendicularly towards the first flow path 61, blow-by gas can flow smoothly into the first flow path 61 along the curved surface E, and resistance to the blow-by gas is reduced. Moreover, with respect to the curved surface E, compared to the case where the downstream end 54a is a corner-shaped wall as described above, more blow-by gas comes into contact with the partition wall 54, so the formation of ice crystals P is suppressed by the space 60. Note that the curved surface E may also be in the shape of a circular arc (for example, a sector-shaped circular arc with a central angle of 90 degrees).

[0039] Furthermore, the inner wall 522a of the end 522 of the second flow path 62 has a curved surface that curves from the extended portion 521 toward the first flow path 61. For example, the inner wall 522a of the second flow path 62 curves in an arc from the extended portion 521 toward the first flow path 61 in an S-shape, and smoothly connects to the inner wall of the first flow path 61. Therefore, the resistance when blow-by gas enters the first flow path 61 from the second flow path 62 is reduced.

[0040] In contrast, if the inner wall 522 is a flat surface that forms an obtuse angle with respect to the wall surface of the extension portion 521 and extends toward the first flow path 61, the blow-by gas will diffuse at the corner between the extension portion 521 and the end portion 522, resulting in greater resistance compared to a curved surface. Therefore, by providing the inner wall 522a of the end portion 522 with a curved surface that curves toward the first flow path 61, it is possible to suppress the resistance experienced by the blow-by gas and reduce pressure loss.

[0041] Thus, the intake duct 5 suppresses the formation of ice crystals P from moisture in the blow-by gas, thereby suppressing damage to the supercharger 2. The inner wall of the second passage 62 may be treated with a water-repellent coating to suppress the formation of ice crystals P. Examples of water-repellent coatings include, but are not limited to, Teflon® coating. In addition, as shown in the following example, heat insulating material or heating means may be provided in the space 60.

[0042] (Other examples) Figure 5(A) illustrates a cross-section of an intake duct 5 in which an insulating material 70 is provided in the space 60 within the partition wall 54. In Figure 5(A), components common to Figure 4 are denoted by the same reference numerals, and their explanations are omitted.

[0043] Examples of the insulating material 70 include PET (Polyethylene Terephthalate), foamed polyurethane, and glass fiber, but are not limited to these, and other materials may be used. In this example, the insulating material 70 more effectively blocks heat between the first channel 61 and the second channel 62, so that the formation of ice crystals P in the second channel 62 is more effectively suppressed compared to the case without the insulating material 70.

[0044] Figure 5(B) illustrates a cross-section of an intake duct 5 in which a heating means 71 is provided in the space 60 within the partition wall 54. In Figure 5(B), components common to Figure 4 are denoted by the same reference numerals, and their descriptions are omitted.

[0045] The heating means 71 may include, but is not limited to, a heater. The heating means 71 is provided in contact with the inner wall 54a on the second channel 62 side and heats the second channel 62. In this example, since the second channel 62 is heated by the heating means 71, the formation of ice crystals P in the second channel 62 is suppressed more effectively compared to the case where there is no heating means 71.

[0046] In this example, the intake duct 5 is given as the intake device for the internal combustion engine, but it is not limited to this. For example, instead of the intake duct 5, the above configuration may be provided in the air cleaner hose extending from the air cleaner 17.

[0047] The embodiments described above are preferred examples of the present invention. However, the invention is not limited thereto, and various modifications are possible without departing from the spirit of the invention. [Explanation of Symbols]

[0048] 10 Engine (internal combustion engine), 11 Internal combustion engine body, 5 Intake duct (intake device), 20 Supercharger, 50 Connection part, 53 Orifice, 54 Partition wall, 60 Space, 61 First flow path, 62 Second flow path, 70 Insulation material, 71 Heating means, 120 Connector part, 522 End (one end), 522a Inner wall, E Curved surface

Claims

1. The internal combustion engine body, A supercharger connected to the internal combustion engine body, The engine comprises an intake device connected to the internal combustion engine body, The intake device is, A first flow path for introducing fresh air into the supercharger, It has a second passage through which blow-by gas flows from the internal combustion engine body, The second flow path extends adjacent to the first flow path and, at one end, merges with the first flow path from diagonally behind in the direction of the flow of fresh air. A space is provided inside the partition wall separating the adjacent first channel and the second channel. Internal combustion engine.

2. The partition wall has a curved surface at one end that bulges out toward the second flow path and curves toward the first flow path. The internal combustion engine according to claim 1.

3. The second passage has a connection portion that is connected to the blow-by gas vent provided in the head cover of the internal combustion engine, The aforementioned connection portion has an orifice, The internal combustion engine according to claim 1.

4. The space has an insulating material provided in it. The internal combustion engine according to claim 1.

5. A heating means is provided in the aforementioned space and has heating means for heating the second flow path, The internal combustion engine according to claim 1.

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