Exhaust purifying structure

Abstract

It suppresses the deterioration of exhaust gas purification performance. [Solution] The exhaust gas purification structure is installed in the vehicle's internal combustion engine and comprises a purification device and a cooling unit. The purification device is configured to purify the exhaust gas generated in the combustion chamber of the internal combustion engine. The cooling unit cools the purification device. The purification device is located in the exhaust gas flow path inside the internal combustion engine. The cooling unit is located near the purification device in the internal combustion engine.

Description

Technical Field

[0001] The present disclosure relates to an exhaust purification structure provided in an internal combustion engine of a vehicle.

Background Art

[0002] A technique is known in which exhaust gas from an internal combustion engine of a vehicle is purified by a purification device having a catalyst. If such a purification device is located at a position distant from the internal combustion engine, the time required for the catalyst to reach the activation temperature when the internal combustion engine is started becomes longer. For this reason, immediately after the internal combustion engine is started, the exhaust gas purification performance of such a purification device may not be sufficiently exhibited, which may make it difficult to cope with the recent tightening of exhaust gas regulations. In contrast, as described in Patent Document 1, a technique is known in which a catalyst portion is disposed in an exhaust port of a combustion chamber of an internal combustion engine.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of Invention

Problems to be Solved by the Invention

[0004] However, in the technique disclosed in Patent Document 1, since the catalyst portion is located in the vicinity of the combustion chamber of the internal combustion engine, it is continuously exposed to high-temperature exhaust gas during operation of the internal combustion engine. While this improves the purification performance of the catalyst portion, the catalytic metal supported on the catalyst may aggregate, which may reduce the purification performance of the catalyst portion.

[0005] In one aspect of the present disclosure, it is desirable to suppress a decrease in exhaust gas purification performance.

Means for Solving the Problems

[0006] One aspect of the present disclosure is an exhaust gas purification structure provided in an internal combustion engine of a vehicle, comprising a purification device and a cooling unit. The purification device is configured to purify the exhaust gas generated in the combustion chamber of the internal combustion engine. The cooling unit cools the purification device. The purification device is located in the exhaust gas flow path inside the internal combustion engine. The cooling unit is located near the purification device in the internal combustion engine.

[0007] According to the above configuration, although the purification device is located in the exhaust gas flow path inside the internal combustion engine, it is cooled by the cooling unit. Therefore, a decrease in the purification performance of the purification device can be suppressed.

[0008] One aspect of the present disclosure further comprises a case portion, which is a cylindrical portion constituting at least a part of the exhaust gas flow path inside an internal combustion engine, and in which a purification device is arranged. The cooling portion may have a recess provided on the inner circumferential surface of a housing portion that houses the case portion in the internal combustion engine. The case portion is arranged in the housing portion, and a cooling portion may be formed as a flow path for a refrigerant to cool the purification device by the space formed between the case portion and the recess.

[0009] With the above configuration, the purification device can be cooled effectively. One aspect of the present disclosure may further include an exhaust pipe having a first end located in an internal combustion engine and a second end located outside the internal combustion engine. The internal section, which is the portion of the exhaust pipe located inside the internal combustion engine, may constitute at least a portion of the exhaust flow path inside the internal combustion engine. A purification device may be located in the internal section.

[0010] One aspect of the present disclosure further comprises a case portion which is a cylindrical portion constituting at least a part of the exhaust flow path inside an internal combustion engine, and in which a purification device is arranged. The outlet portion of the case portion, which includes the exhaust outlet, may protrude from the internal combustion engine. The outer circumferential surface of the outlet portion may be provided with a projection that encircles the outlet portion.

[0011] With the above configuration, the outlet portion of the case protruding from the internal combustion engine and the exhaust pipe can be fastened together using a clamp or the like. One aspect of the present disclosure further comprises a case portion, which is a cylindrical portion constituting at least a part of the exhaust gas flow path inside an internal combustion engine, and in which a purification device is arranged. Threads may be formed on the outer circumferential surface of the case portion. Threads may be formed on the inner circumferential surface of a housing portion that accommodates the case portion in the internal combustion engine. The case portion may be screwed into the housing portion.

[0012] With the above configuration, the case section can be securely joined to the housing section. In one aspect of this disclosure, threads may be formed on the outer circumferential surface of the case portion. Threads may be formed on the inner circumferential surface of the housing portion that accommodates the case portion in an internal combustion engine. The case portion may be screwed into the housing portion. The top of the protruding portion may be provided with a plurality of flat portions arranged to surround the outlet portion.

[0013] The above configuration makes it easier to screw the case into the housing using a tool. [Brief explanation of the drawing]

[0014] [Figure 1] This is an explanatory diagram showing the internal combustion engine of the first embodiment as viewed from above the vehicle. [Figure 2] This is an explanatory diagram of the exhaust purification structure of the internal combustion engine of the first embodiment, as viewed from the side of the vehicle. [Figure 3] This is an explanatory diagram of the exhaust purification structure of the internal combustion engine of the second embodiment, as viewed from the side of the vehicle. [Figure 4] This is an explanatory diagram of the exhaust purification structure of the internal combustion engine of the third embodiment, as viewed from the side of the vehicle. [Modes for carrying out the invention]

[0015] Embodiments to which this disclosure applies will be described below with reference to the drawings. [1. First Embodiment] [(1) Configuration of an internal combustion engine] The internal combustion engine 1 according to the first embodiment is mounted on a vehicle and used as a power source for propelling the vehicle (see FIG. 1 and FIG. 2). The vehicle includes various automobiles including motorcycles or four-wheeled vehicles. In addition, the internal combustion engine 1 may have various configurations such as a gasoline engine, a diesel engine, a two-cycle engine, a four-cycle engine, and a rotary engine, for example. The internal combustion engine 1 is configured as a reciprocating engine as an example, and includes a main body portion 10, a plurality of cylinders 13, a plurality of intake ports 14, a plurality of exhaust ports 15, and a collecting portion 16. The number of cylinders 13 is three as an example, but may be determined as appropriate.

[0016] The main body portion 10 has a cylinder head 11 and a cylinder block 12. The cylinder block 12 has the cylinders 13 formed therein and accommodates a crankshaft and the like inside. The cylinder head 11 is disposed on the upper portion of the cylinder block 12 and forms the top of each cylinder 13.

[0017] Each cylinder 13 has a cylindrical space in which a piston 13A is disposed, and a combustion chamber 13B is formed between the upper end of the piston 13A and the cylinder head 11. In addition, the combustion chamber 13B of each cylinder 13 is provided with two exhaust valves 13C as an example, and is also provided with two intake valves. Needless to say, the number of exhaust valves 13C and intake valves provided in each combustion chamber 13B is not limited to this, and may be determined as appropriate.

[0018] The intake port 14 is provided inside the cylinder head 11 corresponding to each cylinder 13, and allows air supplied from an unillustrated intake manifold to flow into the combustion chamber 13B of the cylinder 13.

[0019] The exhaust port 15 is an exhaust flow path provided inside the cylinder head 11 corresponding to each cylinder 13, and is connected to the combustion chamber 13B via two exhaust valves 13C provided in the cylinder 13. The exhaust port 15 is configured to cause exhaust gas flowing out from each combustion chamber 13B via the exhaust valves 13C to flow downward.

[0020] The collecting portion 16 is an exhaust flow path formed by a plurality of exhaust ports 15 merging together, and is provided inside the cylinder head 11. The end of the collecting portion 16 on the upstream side in the exhaust flow direction is connected to each of the exhaust ports 15, and the end on the downstream side forms an opening in the side surface of the cylinder head 11. The portion of the collecting portion 16 adjacent to the opening constitutes an accommodating portion 17 (details of which will be described later) that forms a columnar accommodating space 17A extending along the axis A as an example, and the exhaust pipe 4 is connected to the opening. That is, exhaust gas from each exhaust port 15 flows into the collecting portion 16, passes through the accommodating portion 17, and flows into the exhaust pipe 4.

[0021] [(2) Exhaust gas purification structure] The internal combustion engine 1 is provided with an exhaust gas purification structure 2 for purifying exhaust gas generated in each combustion chamber 13B (see Figures 1 and 2). The exhaust gas purification structure 2 includes a purification device 20, a cooling portion 21, and a case portion 3.

[0022] <Purification Device> The purification device 20 is a member for purifying exhaust gas, and as an example, may be a columnar catalyst (see Figures 1 and 2). More specifically, the purification device 20 may have a configuration in which a catalytic substance such as platinum is supported on a carrier such as porous ceramics, for example. Besides this, the purification device 20 may be, for example, a metal catalyst. The purification device 20 is disposed in the exhaust gas flow path inside the internal combustion engine 1.

[0023] <Cooling Portion> The cooling section 21 is a part for cooling the purification device 20 and is located near the purification device 20 inside the internal combustion engine 1 (see Figures 1 and 2). The cooling section 21 is configured, for example, as a refrigerant flow path. The refrigerant may be, for example, the coolant of the internal combustion engine 1. That is, the refrigerant may be circulated through a flow path provided in the vehicle by a water pump (not shown) provided in the internal combustion engine 1 and cooled by a radiator (not shown). In addition, for example, the refrigerant may be a refrigerant used to cool other on-board equipment (e.g., an air conditioner), or a dedicated refrigerant provided for cooling the purification device 20 may be used.

[0024] <Case section> The case portion 3 is a cylindrical (for example, cylindrical) part extending along axis A, and is positioned in the housing portion 17 (see Figures 1 and 2). Axis A passes through, for example, the center of a cross-section (hereinafter simply referred to as the cross-section) perpendicular to axis A in the case portion 3. The case portion 3 has an insertion portion 30 and an outlet portion 31.

[0025] The insertion portion 30 is inserted into the housing portion 17 inside the cylinder head 11. For example, the insertion portion 30 may be welded to the housing portion 17. The outlet portion 31 is the part that protrudes from the opening of the housing portion 17 to the outside of the cylinder head 11 when the case portion 3 is positioned in the housing portion 17. The exhaust gas that flows into the manifold portion 16 passes through the inside of the case portion 3 and flows out to the outside of the internal combustion engine 1 from the outlet portion 31.

[0026] Furthermore, the inner circumferential surface of the housing section 17 is provided with a recess that constitutes at least a part of the cooling section 21. The outer circumferential surface of the insertion section 30 of the case section 3, which is placed in the housing section 17, covers the opening of the cooling section 21, and a space is formed between the insertion section 30 and the cooling section 21, which becomes a flow path for the refrigerant.

[0027] Furthermore, gaskets 22A and 22B are provided near the upstream end and downstream end of the insertion portion 30, respectively, so as to encircle the outer surface of the case portion 3. Gasket 22A is sandwiched between the case portion 3 and the cylinder head 11, sealing the gap between these parts. Gasket 22B is sandwiched between the case portion 3, the cylinder head 11, and the flange 40, sealing the gap between these parts.

[0028] For example, the cooling section 21 is provided so as to encircle the insertion section 30, and the refrigerant flowing down the cooling section 21 comes into contact with the outer circumferential surface of the insertion section 30. However, the cooling section 21 is not limited to this configuration, and may, for example, be provided without encircling the insertion section 30.

[0029] Furthermore, the exhaust pipe 4 is connected to the opening of the housing portion 17 in the cylinder head 11, and the flange 40 surrounding the opening of the exhaust pipe 4 is joined to the cylinder head 11 by bolts, for example. The outlet portion 31 protruding from the opening of the housing portion 17 is inserted into the exhaust pipe 4.

[0030] Furthermore, a purification device 20 is arranged inside the insertion section 30. The purification device 20 is located inside the cylinder head 11, and at least a portion of the purification device 20 faces the cooling section 21. As an example, the purification device 20 is arranged inside the insertion section 30 with a retaining member 20A wrapped around its outer circumference. The retaining member 20A may be made of, for example, glass wool.

[0031] [2. Second Embodiment] [(1) Overview] The exhaust gas purification structure 2 of the second embodiment differs from the first embodiment in the configuration of the cooling section 21 and in having an exhaust pipe 4 instead of a case section 3 (see Figure 3). The differences between the second embodiment and the first embodiment will be explained below.

[0032] [(2) Exhaust pipe] In the second embodiment, an exhaust pipe 4 is inserted into the housing 17 of the internal combustion engine 1, instead of the case 3 (see Figure 3). The exhaust pipe 4 is a component for discharging exhaust gas from the internal combustion engine 1 to the outside of the vehicle, and the downstream end of the exhaust pipe 4 is located outside the internal combustion engine 1 and is connected to an exhaust component. The exhaust component may be, for example, a device for purifying exhaust gas, and one example may be a catalytic converter.

[0033] In other words, the internal section 4A of the exhaust pipe 4, including the upstream end, is inserted into the housing section 17, forming an exhaust flow path inside the internal combustion engine 1. Furthermore, the exhaust pipe 4 is welded to the housing section 17, for example.

[0034] Furthermore, a flange 40 is provided near the downstream end of the internal section 4A on the outer circumferential surface of the exhaust pipe 4. The flange 40 is joined, for example, by bolts around the opening of the housing portion 17 in the cylinder head 11. A gasket 22 is also provided along the edge of the opening. The gasket 22 surrounds the exhaust pipe 4 and is sandwiched between the exhaust pipe 4, the cylinder head 11, and the flange 40, sealing the gap between these parts.

[0035] [(3) Cooling section] In the second embodiment, the cooling section 21 is configured as a refrigerant flow path located away from the inner circumferential surface of the housing section 17 (see Figure 3). In other words, in the second embodiment, the refrigerant flowing down the cooling section 21 does not come into contact with the exhaust pipe 4 inserted into the housing section 17.

[0036] Furthermore, the cooling unit 21 is provided, for example, to encircle the housing unit 17. However, it is not limited to this configuration, and the cooling unit 21 may be provided without encircling the housing unit 17, for example.

[0037] [(4) Purification device] A purification device 20, with a retaining member 20A wrapped around its outer surface, is positioned in the internal section 4A of the exhaust pipe 4 (see Figure 3). Similar to the first embodiment, the purification device 20 is located inside the cylinder head 11, and at least a portion of the purification device 20 faces the cooling unit 21.

[0038] [3. Third Embodiment] [(1) Overview] The third embodiment differs from the first embodiment in the configuration of the housing section 17, cooling section 21, and case section 3 of the exhaust purification structure 2, and in the configuration of the exhaust pipe 4 (see Figure 4). The differences between the third embodiment and the first embodiment will be described below.

[0039] [(2) Cooling section] In the third embodiment, similar to the second embodiment, the cooling section 21 is configured as a refrigerant flow path located away from the inner circumferential surface of the housing section 17 (see Figure 4). Furthermore, the cooling section 21 is provided to circumfer the housing section 17, for example. However, it is not limited to this configuration, and the cooling section 21 may be provided without circumferencing the housing section 17, for example.

[0040] [(3) Case section and storage section] The housing section 17 of the third embodiment differs from that of the first embodiment in the shape of the housing space 17A (see Figure 4). Specifically, the housing space 17A is cylindrical and tapered, with the diameter of the cross-section decreasing towards the upstream side. Furthermore, the housing section 17 of the third embodiment differs from that of the first embodiment in that threads are formed on the inner circumferential surface.

[0041] Furthermore, the insertion portion 30 of the case portion 3 in the third embodiment differs from the first embodiment in that it is tapered, with the diameter of the cross-section decreasing towards the upstream opening, and that threads are formed on the outer surface of the insertion portion 30. In the third embodiment, the insertion portion 30 is screwed into the housing portion 17.

[0042] For example, the threads of the insertion portion 30 and the housing portion 17 constitute pipe tapered threads as defined in JIS standards. Furthermore, the housing space 17A of the insertion portion 30 and the housing portion 17 may not be tapered, but may have a constant cross-sectional diameter. Also, the insertion portion 30 and the housing portion 17 may not have threads formed on them.

[0043] Furthermore, the outlet portion 31 of the case portion 3 in the third embodiment differs from that of the first embodiment in that a protruding portion 32 is provided. The protruding portion 32 is a protruding part on the outer circumferential surface of the outlet portion 31, located near the downstream opening of the outlet portion 31, and surrounding the outlet portion 31.

[0044] Furthermore, multiple planar sections 33 are provided at the top of the protruding section 32. Each planar section 33 is arranged substantially parallel to any other planar section 33, with axis A in between. In this embodiment, as an example, the exit section 31 is provided with six planar sections 33, which are arranged in the circumferential direction around axis A at substantially constant intervals. In other words, when viewed in the direction of axis A, the six planar sections 33 are each arranged along the sides of a regular hexagon.

[0045] [(4) Exhaust pipe] In the third embodiment, a flared connecting portion 41 is provided on the edge surrounding the upstream opening of the exhaust pipe 4, and the upstream opening of the exhaust pipe 4 and the downstream opening of the case portion 3 are fastened together by a clamp 5 (see Figure 4).

[0046] In other words, the connection portion 41 of the exhaust pipe 4 is in contact with the protruding portion 32 of the outlet portion 31 of the case portion 3, and the clamp 5 is positioned to cover the connection portion 41 and the protruding portion 32 from the outside. At this time, the portion near the opening of the outlet portion 31 is inserted into the inside of the exhaust pipe 4. Then, the exhaust pipe 4 and the case portion 3 are connected by fastening the clamp 5 with a bolt.

[0047] Furthermore, a gasket 22 is provided along the edge of the opening of the housing portion 17 in the cylinder head 11. The gasket 22 surrounds the case portion 3 and is sandwiched between the case portion 3 and the cylinder head 11, sealing the gap between these parts.

[0048] [4. Effects] (1) According to the exhaust gas purification structure 2 of the first to third embodiments, the purification device 20 is located in the exhaust gas flow path inside the internal combustion engine 1, but is cooled by the cooling unit 21. Therefore, a decrease in the purification performance of the purification device 20 can be suppressed.

[0049] (2) Furthermore, according to the exhaust gas purification structure 2 of the first embodiment, the cooling unit 21 has a recess formed on the inner circumferential surface of the housing unit 17 in the internal combustion engine 1, and the purification device 20 is cooled by the refrigerant flowing through the passage between the recess and the housing unit 17. Therefore, the purification device 20 can be cooled effectively.

[0050] (3) Furthermore, according to the exhaust gas purification structure 2 of the second embodiment, an exhaust pipe 4 is inserted into the housing 17 of the internal combustion engine 1, and the purification device 20 is arranged in the internal section 4A of the exhaust pipe 4 located inside the internal combustion engine 1. Therefore, the purification device 20 can be arranged well while reducing the number of parts.

[0051] (4) Furthermore, according to the exhaust purification structure 2 of the third embodiment, a protruding portion 32 is formed near the opening of the outlet portion 31 that protrudes from the internal combustion engine 1. Therefore, the outlet portion 31 and the exhaust pipe 4 can be fastened together with a clamp 5.

[0052] (5) In addition, in the exhaust purification structure 2 of the third embodiment, threads are formed on the outer circumferential surface of the insertion portion 30 of the case portion 3 and on the inner circumferential surface of the housing portion 17, and the insertion portion 30 is screwed into the housing portion 17. Therefore, the insertion portion 30 can be joined to the housing portion 17 well.

[0053] (6) In addition, in the exhaust purification structure 2 of the third embodiment, a plurality of flat surfaces 33 are formed on the top of the protruding portion 32 of the outlet portion 31 in the case portion 3. This makes it easier to screw the case portion 3 into the housing portion 17 using a tool such as a pipe wrench.

[0054] [5. Other Embodiments] (1) In the first embodiment, the cooling section 21 of the exhaust purification structure 2 has a recess on the inner circumferential surface of the housing section 17 that forms a refrigerant flow path. However, the cooling section 21 may be configured as a refrigerant flow path located away from the inner circumferential surface of the housing section 17, as in the second and third embodiments. Conversely, the cooling section 21 of the second and third embodiments is configured as a refrigerant flow path located away from the inner circumferential surface of the housing section 17. However, the cooling section 21 may be configured as a refrigerant flow path located away from the inner circumferential surface of the housing section 17, as in the first embodiment.

[0055] (2) In the first embodiment, as in the third embodiment, threads may be formed on the outer circumferential surface of the insertion portion 30 of the case portion 3 and on the inner circumferential surface of the housing portion 17, and the housing space 17A of the insertion portion 30 and the housing portion 17 may be tapered. Also in the second embodiment, as in the third embodiment, threads may be formed on the outer circumferential surface of the internal section 4A of the exhaust pipe 4 and on the inner circumferential surface of the housing portion 17, and the internal section 4A and the housing space 17A may be tapered.

[0056] (3) The internal combustion engine 1 of the first to third embodiments is provided with a manifold 16 into which the exhaust ports 15 extending from each combustion chamber 13B converge, and a housing 17 is provided in the manifold 16. However, the invention is not limited to this, and the internal combustion engine 1 may not have a manifold 16, and the exhaust ports 15 extending from each combustion chamber 13B may be open to the outside of the internal combustion engine 1. Alternatively, an exhaust manifold provided outside the internal combustion engine 1 may be used to merge the exhaust flow paths from the exhaust ports 15. Furthermore, an exhaust purification structure may be provided in each exhaust port 15 inside the internal combustion engine 1, in the same manner as in the first to third embodiments.

[0057] (4) Multiple functions of one component in the above embodiment may be realized by multiple components, or one function of one component may be realized by multiple components. Also, multiple functions of multiple components may be realized by one component, or one function realized by multiple components may be realized by one component. Furthermore, some of the configurations of the above embodiment may be omitted. Also, at least some of the configurations of the above embodiment may be added to or replaced with the configurations of other above embodiments. [Explanation of Symbols]

[0058] 1...Internal combustion engine, 10...Main body, 11...Cylinder head, 12...Cylinder block, 13...Cylinder, 13A...Piston, 13B...Combustion chamber, 13C...Exhaust valve, 14...Intake port, 15...Exhaust port, 16...Collection section, 17...Housing section, 2...Exhaust purification structure, 20...Purification device, 20A...Retaining member, 21...Cooling section, 22...Gasket, 3...Case section, 30...Insertion section, 31...Outlet section, 32...Protruding section, 33...Flat section, 4...Exhaust pipe, 4A...Internal section, 40...Flange, 41...Connection section, 5...Clamp.

Claims

1. An exhaust purification structure installed in the internal combustion engine of a vehicle, A purification device configured to purify exhaust gas generated in the combustion chamber of the internal combustion engine, The purification device comprises a cooling unit for cooling the device, The purification device is located in the exhaust gas flow path inside the internal combustion engine. The cooling unit is located near the purification device in the internal combustion engine. Exhaust gas purification structure.

2. The exhaust gas purification structure according to claim 1, A cylindrical portion that constitutes at least a part of the exhaust gas flow path inside the internal combustion engine, further comprising a case portion which is the portion in which the purification device is arranged, The cooling section has a recess provided on the inner circumferential surface of the housing section that houses the case section of the internal combustion engine, The case portion is positioned in the housing portion, and the cooling portion, which serves as a flow path for refrigerant to cool the purification device, is formed by the space formed between the case portion and the recess. Exhaust gas purification structure.

3. The exhaust gas purification structure according to claim 1, The system further comprises an exhaust pipe, the first end of which is located on the internal combustion engine and the second end of which is located outside the internal combustion engine. The internal section of the exhaust pipe, which is the portion located inside the internal combustion engine, constitutes at least a part of the exhaust flow path inside the internal combustion engine. The purification device is located in the internal section. Exhaust gas purification structure.

4. The exhaust gas purification structure according to claim 1, A cylindrical portion that constitutes at least a part of the exhaust gas flow path inside the internal combustion engine, further comprising a case portion which is the portion in which the purification device is arranged, The outlet portion, which includes the exhaust outlet in the case portion, protrudes from the internal combustion engine. The outer circumferential surface of the outlet portion is provided with a projection that encircles the outlet portion. Exhaust gas purification structure.

5. An exhaust gas purification structure according to claim 1 or claim 4, A cylindrical portion that constitutes at least a part of the exhaust gas flow path inside the internal combustion engine, further comprising a case portion which is the portion in which the purification device is arranged, If a screw is formed on the outer surface of the case portion, A screw is formed on the inner circumferential surface of the housing portion that houses the case portion of the internal combustion engine. The case portion is screwed into the housing portion. Exhaust gas purification structure.

6. The exhaust gas purification structure according to claim 4, If a screw is formed on the outer surface of the case portion, A screw is formed on the inner circumferential surface of the housing portion that houses the case portion of the internal combustion engine. The case portion is screwed into the housing portion, Multiple flat surfaces are provided at the top of the protruding portion, arranged to surround the exit portion. Exhaust gas purification structure.

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