JP2010248915A - Exhaust device for outboard engine and outboard engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust device in a high riser structure, materializing a small form in spite applicable a large capacity catalyst. <P>SOLUTION: This device includes a guide exhaust 2 having a passage hole 31 in which exhaust gas from the engine 3 is discharged formed thereon, and a cylindrical catalyst housing 43 formed on an oil pan 11 so as to communicate to the passage hole 31 and extending vertically. The device includes many independent channels extending vertically and catalyst 42 filled in the catalyst housing 43. The device includes a first passage 81 leading exhaust gas from the passage hole 31 to a lower part of the catalyst 42 through a half part 42a of the catalyst 42, a second passage 82 leading the exhaust gas led to a lower end of the first passage 81 to an upper part of the catalyst 42 through at least part of a half part 42b of the catalyst 42, and a third passage 83 leading the exhaust gas led to the upped end of the second passage 82 to a lower part. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an exhaust device for an outboard motor having a portion higher than the catalyst on the downstream side of the catalyst in the exhaust passage, and an outboard motor equipped with the exhaust device.

  A conventional exhaust device for an outboard motor has a configuration in which exhaust gas is mainly discharged into water. On the other hand, in a ship equipped with an outboard motor, for example, when stopping the hull, the propeller may be reversed by switching the forward / reverse switching mechanism of the outboard motor from the forward state to the reverse state. In this case, when the engine output suddenly decreases or misfires due to the sudden closing of the throttle valve, and the engine speed decreases, the propeller is forcibly rotated forward by water pressure, and the engine may reverse. .

When the engine rotates in the reverse direction, the pressure in the exhaust passage becomes negative and water rises in the exhaust passage. In this case, if a catalyst or an air-fuel ratio sensor is provided in the exhaust passage, water that has risen in the exhaust passage may come into contact with these catalyst or air-fuel ratio sensor.
In order to prevent the water rising in the exhaust passage from coming into contact with the catalyst, for example, it is conceivable to adopt the configuration described in Patent Document 1.

  The exhaust system for an outboard motor disclosed in Patent Document 1 has a structure in which exhaust gas discharged downward from an engine is reversed and raised on the downstream side of the catalyst, and is reversed and lowered again at a position higher than the catalyst (hereinafter, referred to as “exhaust device”). This structure is simply called a riser structure). The high riser structure includes a first passage portion for guiding exhaust gas discharged from the engine downward, a second passage portion extending upward from a lower end portion of the first passage portion, and the second passage portion. It is comprised by the 3rd channel | path part extended below from the upper end part of a channel | path part.

  In the exhaust device shown in Patent Document 1, the catalyst is provided in the first passage portion. Moreover, the connection part of the 2nd channel | path part and the 3rd channel | path part is located in the substantially same height as the upper end part of a catalyst. According to this exhaust device, the water does not contact the catalyst until the water rises up to substantially the same height as the upper end of the catalyst and flows into the second passage from the third passage. Can keep you.

  In the exhaust device disclosed in Patent Document 1, the catalyst and the passage member that realizes the riser structure are formed as one assembly. This assembly is disposed at a position adjacent to an oil tank (oil pan) provided below the engine. The oil tank is formed in a shape in which an oil storage portion is located on the rear side and one side of the assembly.

Japanese Patent No. 4073535

  The exhaust device with the above-described high riser structure has an exhaust passage (second passage portion and third passage) for raising and lowering exhaust gas in addition to an exhaust passage (first passage portion) for guiding exhaust gas downward and passing it through the catalyst. There is a problem that a large space is required below the engine.

  In an outboard motor, the space for mounting components below the engine is limited. Therefore, if a large exhaust device with a high riser structure is provided in this space, the space for installing the oil pan is reduced. For this reason, the outboard motor equipped with the exhaust device shown in Patent Document 1 cannot use an oil pan having a large volume. In this outboard motor, in order to use a large-capacity oil pan, a small catalyst must be used to make the exhaust device small. Thus, when the capacity of the catalyst is reduced, the exhaust gas cannot be sufficiently purified.

  The present invention has been made to solve such problems, and a first object of the present invention is to provide an exhaust device having a high riser structure that can be formed in a small size even though a large-capacity catalyst can be used. . It is a second object of the present invention to provide an outboard motor capable of sufficiently purifying exhaust gas and mounting a large-capacity oil pan in spite of being equipped with the exhaust device having the high riser structure.

  In order to achieve this object, an exhaust system for an outboard motor according to the present invention includes an engine support member that supports an engine in which a passage hole for discharging exhaust gas from the engine is formed, and a lower portion of the engine support member. A cylindrical catalyst housing formed to communicate with the passage hole in a disposed oil pan and extending in the vertical direction; and a number of independent flow paths extending in the vertical direction; The loaded catalyst, the first passage portion for guiding the exhaust gas discharged from the engine from the passage hole to the lower part of the catalyst through a part of the catalyst, and the exhaust gas led to the lower end portion of the first passage portion. A second passage portion that leads upward of the catalyst through at least a part of the remaining portion of the catalyst, and a third passage portion that guides the exhaust gas led to the upper end portion of the second passage portion downward. is there.

  According to a second aspect of the present invention, in the exhaust apparatus for an outboard motor according to the first aspect, the catalyst housing is opened at a lower surface of the oil pan, and the lower end of the oil pan is disposed below the catalyst housing. A lid member that forms a lower end portion of the first passage portion and a lower end portion of the second passage portion is attached.

  According to a third aspect of the present invention, in the exhaust system for an outboard motor according to the first or second aspect, the connection portion between the first passage portion and the second passage portion is the lowest portion. A drainage valve that is opened and closed by a ceramic floating body is provided.

  According to a fourth aspect of the present invention, there is provided an outboard motor according to any one of the first to third aspects.

According to the present invention, the first passage portion and the second passage portion can be formed in one catalyst. For this reason, the occupation space of the exhaust device according to the present invention is only a space for installing the catalyst and a space for forming the third passage portion.
Therefore, the exhaust system for the outboard motor according to the present invention does not require the installation space for the second passage portion if the size of the catalyst is the same as that of the conventional exhaust system described in Patent Document 1. It can be made compact by as much.

Further, in this exhaust device, the catalyst housing is formed in the oil pan, and the catalyst portion and the oil storage portion of the oil pan can be brought closer to each other compared to the case where the catalyst housing and the oil pan are formed separately. It becomes possible.
As a result, according to the present invention, it is possible to provide an exhaust device having a high riser structure which is formed in a small size, despite being equipped with a catalyst having a size capable of sufficiently purifying exhaust gas.

  Furthermore, the outboard motor equipped with this exhaust system can sufficiently purify exhaust gas and has a large-capacity oil pan in spite of adopting a configuration in which the water rising in the exhaust passage is difficult to contact the catalyst. Can be installed.

1 is a side view of an outboard motor according to the present invention. It is sectional drawing seen from the side of the principal part. It is sectional drawing seen from the back of the principal part, In the same figure, it has drawn in the state which mounted the cylinder body in the guide exhaust. It is the IV-IV sectional view taken on the line in FIG. It is the VV sectional view taken on the line in FIG. It is a bottom view of a guide exhaust and an oil pan. It is sectional drawing which expands and shows a catalyst support part. FIG. 4A is a cross-sectional view showing a drain valve, in which FIG. 1A shows a state where water is not stored, and FIG. 1B shows a state where water is drained.

  Hereinafter, an embodiment of an exhaust device according to the present invention and an outboard motor equipped with the exhaust device will be described in detail with reference to FIGS. 1, 2, 5, and 6, the front of the outboard motor is indicated by an arrow F.

  An outboard motor 1 shown in FIG. 1 includes a guide exhaust 2 attached to a hull (not shown), an engine 3 mounted on the guide exhaust 2, and an upper casing 4 attached below the guide exhaust 2. The lower casing 5 attached to the lower end portion of the upper casing 4, the propeller 6 rotatably supported by the lower casing 5, and the exhaust device that discharges exhaust gas of the engine 3 from the shaft center portion of the propeller 6 into the water. 7 etc. The propeller 6 is connected to the drive shaft 9 via a forward / reverse switching mechanism 8 provided in the lower casing 5. The drive shaft 9 extends in the vertical direction inside the front portion of the outboard motor 1 and is rotated by the crankshaft 10 of the engine 3.

  The exhaust device 7 according to this embodiment includes the guide exhaust 2, an oil pan 11 attached to the lower end portion of the guide exhaust 2, an upper muffler 12 attached to the lower end portion of the oil pan 11, and the upper muffler 12 has an exhaust passage 14 (see FIG. 2) that vertically penetrates the lower muffler 13 attached to the lower end portion of the engine 12. The exhaust passage 14 discharges exhaust gas from the engine 3 to the exhaust passage 15 in the lower casing 5. The structure to do is taken. A downstream end portion of the exhaust passage 15 in the lower casing 5 is open to a boss portion of the propeller 7. For this reason, when the engine 3 is stopped, water enters the exhaust passages 14 and 15.

  The engine 3 is a four-cycle four-cylinder engine, and a cylinder body 21 and a crankcase 22 that support the crankshaft 10, a cylinder head 23 attached to a rear end portion of the cylinder body 21, and a rear end of the cylinder head 23. The head cover 24 attached to the part is provided. The lubricating oil for the engine 3 is stored in an oil pan 11 (see FIGS. 2 and 3) described later.

  As shown in FIG. 3, the cylinder body 21 of the engine 3 has four cylinder holes 25, passage holes 26 for each cylinder connected to an exhaust port (not shown) of the cylinder head 23, and these passage holes. A main passage hole 27 is formed to collect the exhaust gas flowing through 26 and guide it downward. The lower end portion of the main passage hole 27 is open to the lower end surface of the cylinder body 21 and is connected to the passage hole 31 of the guide exhaust 2. The upper end of the exhaust passage 14 is formed by the passage hole 31.

The passage hole 31 of the guide exhaust 2 is formed so as to penetrate the guide exhaust 2 in the vertical direction. As shown in FIGS. 2 and 3, the lower end portion of the passage hole 31 is connected to a first passage hole 32 of the oil pan 11 described later.
Although not shown, the guide exhaust 2 has a steering shaft connected to the front end portion thereof, and is supported on the hull side bracket via the steering shaft so as to be steerable and tiltable. The guide exhaust 2 constitutes an engine support member in the present invention.

  As shown in FIG. 3, the passage hole 31 of the guide exhaust 2 is formed so as to be gradually inclined so as to be located at the center in the width direction of the guide exhaust 2. Further, as shown in FIG. 2, a recess 33 is formed behind the passage hole 31 so that the lower end portion of the guide exhaust 2 is partially recessed.

  As shown in FIGS. 2 and 3, the oil pan 11 is accommodated in the upper casing 4 and is attached to the lower end portion of the guide exhaust 2 by fixing bolts 34 and 35. A water chamber 37 is formed between the oil pan 11 and the upper casing 4 for temporarily storing the cooling water 36 after cooling the engine 3.

  The oil pan 11 has an oil storage part 41 in which oil (not shown) is stored, a catalyst housing 43 for accommodating a catalytic converter 42 (hereinafter simply referred to as catalyst), and an upper end part of the catalyst housing 43. The first and second passage holes 32 and 44 extending upward from the first and second passage holes 45 extending in the vertical direction behind the catalyst housing 43 (rightward in FIG. 2) are formed. Yes. As shown in FIG. 5, the oil storage part 41 is formed in a shape surrounding the catalyst housing 43 from the front and both sides. An oil strainer pipe 46 for sucking up oil is provided in the front part of the oil storage part 41.

  Although not shown in detail, the catalyst 42 is called a so-called metal catalyst, and is a spiral plate-shaped carrier 47 (see FIGS. 2, 3 and 5) 47 and this plate. The cylinder 48 includes a cylindrical carrier 47 and fixing flanges 49 and 50 welded to both ends of the cylinder 48. The outer shape of the plate-like carrier 47 is formed to be a perfect circle (see FIG. 5) when viewed from the direction in which the exhaust gas flows, so that the spiral winding operation can be simplified and easily manufactured. In FIG. 5, the plate-like carrier 47 wound in a spiral shape is simplified and drawn simply in a mesh shape.

  The plate-like carrier 47 is provided with a partition member (not shown) extending in parallel with the center line of the cylinder 48 so that a large number of independent flow paths are formed in a spiral state. ing. The independent flow path has a structure in which the exhaust gas flowing through the independent flow path does not leak into other flow paths. The catalyst 42 may be made of a ceramic catalyst as a support in addition to the metal catalyst.

  The catalyst housing 43 is formed in a cylindrical shape into which the catalyst 42 can be inserted, and opens downward at the lower end of the oil pan 11. The catalyst housing 43 is integrally formed with the oil storage portion 41 and the third passage hole 45 by casting. Further, as shown in FIG. 5, the catalyst housing 43 is positioned at the center portion in the front-rear direction of the oil pan 11 and at the center portion in the width direction. As shown in FIGS. 2, 3, and 5, the catalyst housing 43 according to this embodiment is formed with a cooling water passage 51 that surrounds the catalyst 42 over the entire circumference.

  As shown in FIG. 2, the catalyst 42 is fixed in the catalyst housing 43 by attaching a fixing plate 52 to the lower surface of the oil pan 11 with the catalyst 42 inserted into the catalyst housing 43 from the opening at the lower end. This is done by sandwiching the catalyst 42 between the fixing plate 52 and the upper end of the catalyst housing 43. As shown in FIG. 7, the fixing flanges 49 and 50 of the catalyst 42 are fitted to the outer peripheral portion of the cylinder 48 and the cylindrical base portions 49a and 50a to be fitted to the inner peripheral portion of the catalyst housing 43. It is comprised from the flange main bodies 49b and 50b extended in the radial inside from the base parts 49a and 50a.

  In a state where the catalyst 42 is attached to the catalyst housing 43, the upper surface of the fixing flange 49 provided at the upper end portion of the catalyst 42 abuts on the upper end portion of the catalyst housing 43 (see FIGS. 2 and 3). The lower surface of the fixing flange 50 provided at the lower end of the catalyst 42 abuts on the fixing plate 52 (see FIG. 7). As shown in FIG. 4, the fixing plate 52 is fixed to the oil pan 11 together with an upper muffler 12 described later by fixing bolts 53.

  The flange main body 49b of the fixing flange 49 provided at the upper end of the catalyst 42 is formed in a shape that follows the opening shape of the first and second passage holes 32 and 44 formed in the upper portion of the catalyst housing 43. ing. As shown in FIG. 6, the opening shapes of the first and second passage holes 32 and 44 according to this embodiment are each formed in a semicircular shape when viewed from below. Specifically, the lower end portion of the first passage hole 32 located on the front side of the outboard motor among the first and second passage holes 32 and 44 is directed forward (leftward in FIG. 6) when viewed from below. It is formed in a semicircular shape that becomes convex.

  On the other hand, the lower end portion of the second passage hole 44 is formed in a semicircular shape that protrudes rearward when viewed from below. As shown in FIG. 6, a flat mating surface 54 is formed around the openings of the passage holes 32 and 44 in order to bring the flange main body 49b into contact therewith. The mating surface 54 includes an annular portion 54 a formed in a circular shape and a straight portion 54 b formed from an end surface of the partition wall 55 that partitions both the passage holes 32 and 44. The flange main body 49b of the fixing flange 49 is formed in a shape that is in close contact with the annular portion 54a and the straight portion 54b.

As shown in FIGS. 2 and 3, the first passage hole 32 is formed to extend in the vertical direction from the upper end surface of the oil pan 11 to the catalyst housing 43. The upper end portion of the first passage hole 32 is connected to the passage hole 31 of the guide exhaust 2.
The second passage hole 44 is curved so as to be gradually directed rearward from the upper end portion of the catalyst housing 43 upward. As shown in FIG. 2, the upper end portion of the second passage hole 44 is the upper end of the oil pan 11 and opens at a position facing the concave portion 33 of the guide exhaust 2. The concave portion 33 covers the upper end portion of the second passage hole 44 and the upper end portion of the third passage hole 45 from above.

  As shown in FIG. 2, the third passage hole 45 extends in the vertical direction along the rear end portion of the catalyst housing 43, and penetrates the rear end portion of the oil pan 11 in the vertical direction. That is, as shown in FIGS. 5 and 6, the third passage hole 45 is formed with the rear wall 43 a of the catalyst housing 43 as a part of the hole wall. The upper end of the rear wall 43a is formed at a position lower than the upper end of the oil pan 11, as shown in FIG. Therefore, the second passage hole 44 and the third passage hole 45 communicate with each other via a space S (see FIGS. 2 and 4) between the upper end of the rear wall 43a and the inner wall surface of the recess 33. Will be.

  As shown in FIG. 2, an idle exhaust passage 61 for discharging exhaust gas during idle operation is connected to a connection portion between the rear end portion of the recess 33 and the third passage hole 45. As shown in FIG. 4, the idle exhaust passage 61 communicates the exhaust passage 14 and the upper space of the water chamber 37. The upper space of the water chamber 37 is communicated with the atmosphere via an idle muffler 62 provided at the rear end portion of the upper casing 4. That is, the exhaust gas during idling flows into the water chamber 37 from the upper end portion of the third passage hole 45 through the idle exhaust passage 61 as shown by an arrow in FIG. As indicated by solid arrows, the air is discharged into the atmosphere through the idle muffler 62.

Air-fuel ratio sensors 63 and 64 comprising O ₂ sensors are attached to the upper end of the recess 33 and the passage wall on the rear side of the outboard motor in the passage hole of the guide exhaust 2. In the outboard motor 1 according to this embodiment, the fuel injection amount and the ignition timing are controlled based on the detection result of one of the air-fuel ratio sensors 63 and 64, and both the air-fuel ratio sensors 63, 64 is used to detect an abnormality of the catalyst 42. As is well known in the art, this abnormality is detected by comparing the amount of oxygen upstream of the catalyst 42 with the amount of oxygen downstream.

  As shown in FIG. 2, the lower end portion of the third passage hole 45 is connected to the passage hole 66 of the upper muffler 12 through a through hole 65 formed in the fixing plate 52. The passage hole 66 is formed to be curved so as to be gradually located on the front side of the outboard motor as it goes downward at the rear end portion of the upper muffler 12.

  In addition to the passage hole 66, the upper muffler 12 has a passage wall 67 for closing the lower end portion of the catalyst housing 43 and an exhaust gas discharged from the passage hole 66 to the lower muffler 13 below. An exhaust gas chamber 68 and a cooling water passage 70 for supplying the cooling water discharged from the cooling water pump 69 (see FIG. 1) to the cooling water passage 51 of the catalyst housing 43 are formed.

  The passage wall 67 is formed in a hemispherical shape that protrudes downward. The upper end portion of the passage wall 67 is in close contact with the lower surface of the fixing plate 52. Further, the space inside the passage wall 67 is communicated with the inside of the catalyst 42 through a through hole 71 formed in the fixing plate 52. In this embodiment, the passage wall 67 and the fixing plate 52 constitute a lid member referred to in the invention according to claim 2.

  A drain valve 72 is provided at the lowest position of the passage wall 67 in order to prevent water from collecting on the upper side of the passage wall 67. Examples of the water accumulated on the passage wall 67 include exhaust condensed water and condensed water. Exhaust condensed water is water that is contained in the exhaust gas that is cooled and condensed in the exhaust passage. Further, the dew condensation water is a dew condensation of moisture in the exhaust passage on the wall surface of the exhaust passage that has cooled after the engine is stopped.

  As shown in FIG. 8, the drain valve 72 according to this embodiment includes a valve housing 73 fixed to the passage wall 67 and a hollow ball-shaped valve body 74 provided inside the valve housing 73. Has been. A space 75 in which the valve body 74 can move in the vertical direction is formed inside the valve housing 73. The upper end portion of the space 75 is communicated with the inner space of the passage wall 67 by the upper water passage 76. A lower end portion of the space 75 is communicated with the exhaust gas chamber 68 by a lower water passage 77.

  The valve body 74 is made of ceramic and is formed of a floating body that floats on water. As shown in FIG. 8A, the valve body 74 closes the lower water passage 77 in a state where it is placed on the upper end opening of the lower water passage 77. Further, the valve body 74 floats when exhaust condensate or condensed water accumulates in the inner space of the passage wall 67 including the inside of the valve housing 73. By moving the valve body 74 upward in this way, the water in the valve housing 73 is discharged into the exhaust gas chamber 68 through the lower water passage 77 as shown in FIG. In this embodiment, the drain valve 72 constitutes a drain valve as referred to in the invention of claim 3.

  The cooling water passage 70 of the upper muffler 12 is formed in a shape surrounding the passage wall 67 from below. Further, a cooling water supply pipe 78 to which cooling water is supplied from a cooling water pump 69 is connected to the cooling water passage 70, and the inside of the catalyst housing 43 is cooled through the through hole 79 of the fixing plate 52. A water passage 51 is connected. Although not shown, the cooling water passage 51 of the catalyst housing 43 is connected to the cooling water inlet of the engine 3 through the cooling water passage of the guide exhaust 2.

  According to the exhaust device 7 of the outboard motor 1 configured as described above, the exhaust gas discharged from the engine 3 is transmitted from the passage hole 31 of the guide exhaust 2 to the oil pan as shown by the black arrows in FIG. 11 into the first passage hole 32 and from here into the upper end of the catalyst 42. At this time, since the first passage hole 32 opens above the half 42a on the front side of the outboard motor of the catalyst 42, the exhaust gas flows into the half 42a from above. Since the catalyst 42 has a structure having a large number of independent flow paths, the exhaust gas flowing into the flow path in the half part 42a from the first passage hole 32 leaks to the half part 42b on the rear side of the outboard motor. Without being discharged into the lower upper muffler 12.

  The exhaust gas discharged into the upper muffler 12 is reversed in the flow direction in the upper muffler 12 and flows into the half portion 42b of the catalyst 42 on the rear side of the outboard motor from below. The exhaust gas is discharged from the catalyst 42 to the second passage hole 44 without leaking to the half portion 42a side on the front side of the outboard motor. The exhaust gas discharged to the second passage hole 44 flows into the third passage hole 45 through the space S and descends in the third passage hole 45. Thereafter, the exhaust gas flows into the lower muffler 13 from the third passage hole 45 through the passage hole 66 of the upper muffler 12 and the exhaust gas chamber 68, and further discharged into the water through the exhaust passage 15 in the lower casing 5. Is done.

  In this embodiment, the passageway 31 of the guide exhaust 2, the half part 42a on the front side of the outboard motor of the catalyst 42, and the front part of the upper muffler 12 are used in the first passage part 81 (FIG. 2). Further, the second passage portion referred to in the present invention includes the rear portion of the upper muffler 12, the half portion 42 b on the rear side of the outboard motor of the catalyst 42, the second passage hole 44, and the front portion of the concave portion 33. 82 is configured.

Furthermore, the rear portion of the recess 33, the third passage hole 45, the passage hole 66 and the exhaust gas chamber 68 of the upper muffler 12, the lower muffler 13, and the exhaust passage 15 in the lower casing 5 are referred to in the present invention. A third passage portion 83 is configured.
For this reason, the 1st channel | path part 81 and the 2nd channel | path part 82 penetrate the catalyst housing 43 of the oil pan 11 to an up-down direction.

Therefore, according to this embodiment, the first passage portion 81 and the second passage portion 82 can be formed in one catalyst 42. For this reason, the space occupied by the exhaust device 7 shown in this embodiment can be limited to a space for installing the catalyst 42 and a space for forming the third passage portion 83.
As a result, the exhaust device 7 of the outboard motor 1 according to this embodiment has an installation space for the second passage portion as compared with the conventional exhaust device described in Patent Document 1, if the size of the catalyst is the same. Miniaturization can be achieved as much as it becomes unnecessary.

  Further, in the exhaust device 7 of this embodiment, the catalyst housing 43 is formed integrally with the oil pan 11. For this reason, according to the exhaust device 7, it is possible to bring the catalyst part and the oil storage part 41 of the oil pan 11 closer to each other as compared with the case where the catalyst housing 43 and the oil pan 11 are formed separately. Further downsizing can be achieved.

  The catalyst housing 43 shown in this embodiment opens on the lower surface of the oil pan 11. Further, a fixing plate 52 and an upper muffler are formed at the lower end of the oil pan 11 to form the lower end of the first passage 81 and the lower end of the second passage 82 below the catalyst housing 43. 12 are attached.

  Therefore, according to this embodiment, the catalyst 42 can be attached to and detached from the catalyst housing 43 with the fixing plate 52 and the upper muffler 12 removed from the catalyst housing 43 from below. Accordingly, the catalyst 42 can be easily replaced.

  Further, in this embodiment, a drain valve 72 is provided at the lowest part of the passage wall 67 (the lowest connection portion between the first passage portion 81 and the second passage portion 82). . Therefore, according to this embodiment, it is possible to prevent the water stored in the exhaust passage 14 from being blown off by the pressure of the exhaust gas and coming into contact with the catalyst 42 and the air-fuel ratio sensors 63 and 64.

  As described above, as a result of achieving the downsizing of the exhaust device 7 having a so-called high riser structure, the outboard motor 1 equipped with the exhaust device 7 has a configuration in which the water rising in the exhaust passage 14 is difficult to contact the catalyst 42. However, the exhaust gas can be sufficiently purified and a large-capacity oil pan 11 can be mounted.

  DESCRIPTION OF SYMBOLS 1 ... Outboard motor, 3 ... Engine, 2 ... Guide exhaust, 5 ... Lower casing, 7 ... Exhaust device, 11 ... Oil pan, 12 ... Upper muffler, 13 ... Lower muffler, 14, 15 ... Exhaust passage, 31 ... Passage Hole 32, first passage hole 42, catalyst, 43 catalyst housing, 44 second passage hole, 45 third passage hole, 52 fixing plate, 67 passage wall, 72 drain valve , 81 ... 1st passage part, 82 ... 2nd passage part, 83 ... 3rd passage part.

Claims (4)

An engine support member that supports the engine in which a passage hole through which exhaust gas from the engine is discharged is formed;
A cylindrical catalyst housing formed in an oil pan disposed below the engine support member so as to communicate with the passage hole and extending in the vertical direction;
A number of independent flow paths extending in the vertical direction, and a catalyst loaded in the catalyst housing;
A first passage portion that guides exhaust gas discharged from the engine from the passage hole to a lower portion of the catalyst through a part of the catalyst;
A second passage portion for guiding the exhaust gas guided to the lower end portion of the first passage portion to above the catalyst through at least a part of the remaining portion of the catalyst;
An outboard motor exhaust system comprising: a third passage portion that guides the exhaust gas led to the upper end portion of the second passage portion downward. The exhaust device for an outboard motor according to claim 1,
The catalyst housing opens to the lower surface of the oil pan,
An exhaust device for an outboard motor, wherein a lid member that forms a lower end portion of the first passage portion and a lower end portion of the second passage portion is attached to a lower end portion of the oil pan below the catalyst housing. The exhaust system for an outboard motor according to claim 1 or 2,
An exhaust system for an outboard motor, wherein a drainage valve that is opened and closed by a ceramic floating body is provided at the lowest portion of the connecting portion between the first passage portion and the second passage portion.   An outboard motor comprising the exhaust device according to any one of claims 1 to 3.

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