JP4735607B2 - Outboard motor - Google Patents

Description

  The present invention relates to an outboard motor, and more particularly to an outboard motor having a structure in which air is introduced into an exhaust passage communicating with an exhaust port of an engine to eliminate negative pressure in the exhaust passage.

  In the outboard motor, the exhaust of the engine is discharged into the water. Therefore, when the pressure in the exhaust passage becomes negative, water may enter the exhaust passage.

  In order to prevent this water from entering, the outboard motor described in Patent Document 1 includes an air supply passage and a check valve that communicate with the exhaust passage, and exhausts the air in the engine cover when negative pressure is present in the exhaust passage. The air is guided into the passage and the negative pressure in the exhaust passage is eliminated to prevent water from entering the exhaust passage.

Further, in the outboard motors described in Patent Documents 2 and 3, one end of the air introduction path is connected to the exhaust passage of the engine and the other end is connected to the upstream side of the intake passage so The air flowing through the passage is guided to the exhaust passage to eliminate the negative pressure in the exhaust passage. One end of the air introduction path is connected to the exhaust passage at a position lower than the central axis of the lowermost cylinder in the multi-cylinder engine.
Japanese Utility Model Publication No. 56-44638 JP-A-7-215294 JP 2002-349257 A

  In the invention described in Patent Document 1, in the unlikely event that the check valve breaks down, high-temperature exhaust in the exhaust passage is directly discharged into the engine cover, which causes a safety problem.

  Moreover, in the outboard motors described in Patent Documents 2 and 3, one end of the air introduction path is connected to the exhaust passage at a position lower than the central axis of the lowermost cylinder. Due to the intrusion of water, there is a possibility that the water may invade to a position above one end of the air introduction path. In this case, the introduction of air through the air introduction path is insufficient, and there is a possibility that the negative pressure in the exhaust passage cannot be sufficiently eliminated.

  In addition, since one end of the air introduction path is connected to the exhaust passage at a low position as described above, water that has entered the exhaust passage when the exhaust introduction valve such as a check valve breaks down reaches the air introduction valve. The durability of this valve may be reduced.

  Furthermore, since the other end of the air introduction path is connected to the upstream side of the intake passage, even when the air introduction valve is closed, the heat of the exhaust is transferred to the intake passage and the intake air is warmed. Not preferable.

  The object of the present invention has been made in consideration of the above-mentioned circumstances, and can eliminate negative pressure in the exhaust passage and prevent water from entering the exhaust passage, and can improve safety and engine performance. It is to provide an outboard motor that can be secured.

  The present invention relates to an outboard motor in which an engine is mounted vertically and the periphery of the engine is covered with an engine cover, and an exhaust portion having an exhaust passage communicating with an exhaust port of a cylinder head of the engine is provided in the engine. An exhaust hole for discharging air warmed in the engine cover is formed in the upper part of the engine cover, and one end of the exhaust part is in the vicinity of the exhaust hole. The other ends are connected to each other, and an air introduction path for introducing air into the exhaust passage at the time of negative pressure in the exhaust passage in the exhaust section is provided.

  According to the present invention, the negative pressure in the exhaust passage is eliminated and water can be prevented from entering the exhaust passage. Further, even if the exhaust gas in the exhaust passage flows back to the air introduction path, the exhaust gas is discharged out of the engine cover through the exhaust air holes, so that safety can be suitably ensured. Furthermore, since the heat of the exhaust is exhausted outside the engine cover through the air introduction path and the exhaust hole, the intake air is not warmed by the heat of the exhaust, and the engine performance can be suitably secured.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

[A] First embodiment (FIGS. 1 to 5)
FIG. 1 is a left-side cross-sectional view showing a first embodiment of an outboard motor according to the present invention, with a part thereof broken away. FIG. 3 is a perspective view showing the engine and the engine holder of FIG.

  An outboard motor 10 shown in FIG. 1 includes an engine holder 12, and the engine 11 is mounted on the engine holder 12. An oil pan block 13, a drive shift housing 14, and a gear case 15 are sequentially assembled to the lower part of the engine holder 12. A portion from the engine 11 to the middle of the drive shift housing 14 is covered with a synthetic resin cover 16, and the engine cover 17 covers the engine 11.

  The upper and lower ends of a pilot shaft 18 are fixed to the engine holder 12 and the drive shaft housing 14, and the pilot shaft 18 is supported by the swivel bracket 19 so as to be rotatable in the left and right (horizontal) direction. The swivel bracket 19 is supported by a clamp bracket 21 via a swivel shaft 20 so as to be rotatable in the vertical (vertical) direction, and the clamp bracket 21 is fixed to a stern portion 22 of the hull. Thereby, the outboard motor 10 is attached to the stern portion 22 so as to be turnable in the horizontal direction and the vertical direction.

  The engine 11 is a four-cycle multi-cylinder engine, for example, a four-cycle in-line four-cylinder engine, with its crankshaft (not shown) oriented vertically and the cylinders 23A, 23B, 23C, 23D (FIG. 4) serving as cylinders oriented horizontally. It is arranged vertically for Further, the engine 11 is configured by assembling a crankcase 24, a cylinder block 25, a cylinder head 26, and a head cover 27 sequentially from the front side to the rear side of the outboard motor 10.

  The rotation of the crankshaft in the engine 11 is transmitted to the drive shaft 28 via a drive gear and a driven gear (not shown). The drive shaft 28 is provided so as to extend vertically in the engine holder 12, the oil pan block 13, the drive shaft housing 14, and the gear case 15, and meshes with a bevel gear mechanism 29 in the gear case 15. Therefore, the rotational force of the crankshaft is transmitted through the drive shaft 28 and the bevel gear mechanism 29 to the propeller shaft 30 that is integrally coupled to the bevel gear mechanism 29 to rotate the propeller 31. The rotation of the propeller 31 is rotated forward or reverse by switching the rotation of the drive shaft 28, which always rotates in one direction, to forward or reverse by the forward / reverse switching mechanism 32, thereby moving the hull forward or backward.

  As shown in FIG. 4, cylinders 23 </ b> A, 23 </ b> B, 23 </ b> C, and 23 </ b> D are provided in the cylinder block 25 of the engine 11. These cylinders 23 </ b> A to 23 </ b> D are arranged in the vertical direction of the outboard motor 10 with the respective central axes Oa, Ob, Oc, Od as the front-rear (horizontal) direction of the outboard motor 10, and each accommodates a piston (not shown). . A combustion chamber (not shown) is formed in the cylinder head 26 of the engine 11 in alignment with the cylinders 23A, 23B, 23C, and 23D, and an intake port (not shown) that communicates with each combustion chamber. Exhaust ports 36A, 36B, 36C, 36D are formed.

  A fuel injector (not shown) for injecting fuel to each intake port is attached to the cylinder head 26, and intake bubbles and exhaust valves (both not shown) for opening and closing each intake port and each exhaust port 36A, 36B, 36C, 36D. Is provided. Further, the cylinder head 26 is provided with a valve operating mechanism (not shown) for operating these intake valves and exhaust valves. The valve mechanism and the like are covered with a head cover 27.

  The crankshaft is disposed in a crank chamber formed by a crankcase 24 and a cylinder block 25, and is connected to each piston in the cylinders 23A, 23B, 23C, and 23D via a connecting rod (not shown). . The piston reciprocates due to the combustion of fuel in each combustion chamber, and this motion is converted into rotational motion by the crankshaft and transmitted to the drive shaft 28 (FIG. 1).

  As shown in FIG. 3, around the engine 11, an intake device 33 and the like are arranged on the right side, and an exhaust device 34 and a starter device 35 and the like are arranged on the left side.

  The intake device 33 includes an intake introduction path 37, a surge tank, an intake manifold (both not shown), and the like. Although the intake air introduction path 37 will be described in detail later, outside air taken in from the intake air inlet 38 (FIG. 1) of the engine cover 17 is introduced through the inlet 39 and is connected to the downstream side of the intake hole 40 (the throttle body ( (Not shown) to the surge tank. The intake manifold communicates the surge tank with each intake port of the cylinder head 26 and guides intake air to each intake port.

  Further, as shown in FIG. 4, the exhaust device 34 is configured such that an exhaust manifold 41 as an exhaust collecting portion extends in a vertical direction on a side portion of the cylinder block 25 in the engine 11. 36A, 36B. An exhaust passage 42 communicating with 36C and 36D is provided. The exhaust passage 42 of the exhaust manifold 41 also communicates with an exhaust discharge port 43 formed in the engine holder 12 to collect exhaust from the exhaust ports 36A, 36B, 36C, and 36D of the engine 11 and collect the exhaust discharge port 43. Lead to.

  Exhaust gas is guided from an exhaust outlet 43 of the exhaust manifold 41 to an exhaust expansion chamber (not shown) of the drive shaft housing 14 via an exhaust passage (not shown) of the oil pan block 13 shown in FIG. Thereafter, the exhaust gas is mainly discharged into the water through the exhaust passage 44 formed around the propeller shaft 30 in the gear case 15.

  The engine 11 is water-cooled, and uses, for example, seawater as cooling water. That is, as shown in FIG. 1, the cooling water is taken in from the water intake port 46 provided in the gear case 15 by the water pump 45 driven by the drive shaft 28. This cooling water is guided to a cooling water passage (not shown) formed in the engine holder 12 through the water tube 47, and a water jacket (not shown) around each cylinder 23A, 23B, 23C, 23D in the cylinder block 25, and Guided to a water jacket (not shown) around each combustion chamber in the cylinder head 26, the cylinders 23A to 23D and the combustion chamber are cooled.

  Further, as shown in FIG. 4, the cooling water guided to the cooling water passage of the engine holder 12 is respectively supplied to the water jacket 48 formed around the exhaust passage 42 of the exhaust manifold 41 in the cylinder block 25 and the cylinder head 26. Guided to a water jacket 49 formed around the exhaust ports 36A, 36B, 36C, and 36D, the exhaust passage 42 and the exhaust ports 36A to 36D are cooled. Incidentally, reference numeral 50 in FIG. 3 denotes a water jacket lid for forming the water jackets 48 and 49.

  The cooling water that has cooled the cylinders 23A to 23D, the combustion chamber, the exhaust passage 42 of the exhaust manifold 41, and the exhaust ports 36A to 36D passes through the other cooling water passages of the engine holder 12 and is exhausted from the drive shaft housing 14 shown in FIG. It flows down to the expansion chamber and drains into the water from the exhaust passage 44 around the propeller shaft 30 of the gear case 15. Here, a thermostat (not shown) is interposed in the above-described cooling water passage, and the flow of the cooling water is controlled by the water temperature.

  As shown in FIG. 4, in the engine 11, a flywheel magnet 51 is attached to an upper end portion of a crankshaft (not shown) to generate electric power, and the flywheel magnet 51 is covered with a magnet cover 52. In order to exhaust the heat of the air heated in the engine cover 17, particularly in the magnet cover 52, a ventilation fan 53 is integrally formed with the flywheel magnet 51, and an air exhaust path 54 is formed in the magnet cover 52. It will be installed continuously. The air heated in the engine cover 17, particularly in the magnet cover 52 by the rotation of the ventilation fan 53, flows in the exhaust passage 54 as shown by the arrow A, and the first exhaust port 55 of the exhaust passage 54 and the engine cover Through the 17 second discharge ports 56, the air is discharged into the atmosphere from the air discharge holes 58 of the tilt-up handle 57 shown in FIG.

  Here, the exhaust passage 54 is provided integrally with the intake air introduction passage 37 as shown in FIG. That is, the intake introduction path 37 is formed on the right side of the flow path case 59 whose upper opening is closed by the lid 60, and the exhaust path 54 is formed on the left side. The inlet 39 and the intake hole 40 of the intake introduction path 37 are provided on the rear side and the front side of the flow path case 59, respectively. Further, the first discharge port 55 of the air exhaust path 54 is opened to the rear side of the lid 60 of the flow path case 59.

  As shown in FIGS. 1 and 2, the engine cover 17 has a recessed portion 61 for attaching the tilt-up handle 57 on the upper rear side, and a second discharge port 56 is opened in the bottom surface 62 of the recessed portion 61. Is done. The second discharge port 56 is formed corresponding to the first discharge port 55 of the exhaust path 54 and is positioned in the vicinity of the exhaust hole 58 of the tilt-up handle 57 attached to the recess 61. Therefore, the air exhaust path 54 is a flow path from the ventilation fan 53 to the air exhaust hole 58.

  By the way, in the outboard motor 10 as described above, the inside of the exhaust passage 42 of the exhaust manifold 41 becomes negative pressure when the rotational speed of the engine 11 shown in FIG. However, there is a risk of entering the exhaust passage 42 through the exhaust passage 44 (FIG. 1) of the gear case 15 and the exhaust expansion chamber of the drive shaft housing 14. In order to prevent this, the engine 11 is provided with an air introduction path 63 that introduces air into the exhaust passage 42 when the exhaust passage 42 has a negative pressure to eliminate the negative pressure.

  One end 67 of the air introduction path 63 is connected to a position higher than the central axis Oa of the uppermost cylinder 23A in the exhaust passage 42 of the exhaust manifold 41 in a side view. The other end 68 of the air introduction path 63 is connected to the middle of the air exhaust path 54 in a flow path case 59 that forms the air exhaust path 54. The other end 68 of the air introduction path 63 is preferably connected to the air exhaust path 54 at a position close to the air exhaust hole 58 of the tilt-up handle 57.

  In the air introduction path 63, a check valve 64 is arranged as an air introduction valve that keeps a valve closed state when the exhaust passage 42 is positive pressure and opens when the exhaust passage 42 is negative pressure shown in FIG. ing. By opening the check valve 64, the air flowing through the exhaust passage 54 is introduced into the exhaust passage 42 as shown by an arrow B in FIG. 5, and the negative pressure in the exhaust passage 42 is eliminated. A water jacket 65 is formed around the air introduction path 63. As the cooling water flows through the water jacket 65, the inside of the air introduction path 63, in particular, the check valve 64 is cooled. Here, a portion of the air introduction path 63 that accommodates the check valve 64 is a valve assembly 69, and a water jacket 65 may be provided in the valve assembly 69.

A catalyst 66 is disposed in the exhaust passage 42 of the exhaust manifold 41 near the exhaust outlet 43 of the engine holder 12. The catalyst 66 is made of, for example, platinum, rhodium or palladium, and oxidizes harmful substances in the exhaust gas flowing in the exhaust passage 42, such as carbon monoxide (CO), hydrocarbons (CH), and nitrogen oxides (NOx). Reduction is promoted, and these are made harmless by changing to carbon dioxide (CO ₂ ), water (H ₂ O), nitrogen (N ₂ ), or the like.

  With the configuration as described above, the following effects (1) to (9) are achieved according to the present embodiment.

  (1) When negative pressure is present in the exhaust passage 42 of the exhaust manifold 41 communicating with the exhaust ports 36A to 36D of the cylinder head 26, the check valve 64 of the air introduction path 63 is opened, and the air introduction path is introduced into the exhaust passage 42. Since the air in the exhaust passage 54 is introduced from 63, the negative pressure in the exhaust passage 42 is eliminated, and water can be prevented from entering the exhaust passage 42.

  (2) Since the other end 68 of the air introduction path 63 is connected in the middle of the air exhaust path 54 from the ventilation fan 53 to the air exhaust hole 58 of the tilt-up handle 57 attached to the engine cover 17. In the unlikely event of a failure of the check valve 64 disposed in the air introduction path 63, even if the exhaust from the exhaust passage 42 flows back into the air introduction path 63, this exhaust passes through the exhaust path 54 and the tilt up handle 57. Since the exhaust air is forcibly discharged from the exhaust path 58 to the atmosphere outside the engine cover 17, safety can be ensured.

  (3) Since the other end 68 of the air introduction path 63 is connected to the exhaust path 54 leading to the exhaust hole 58, the heat of the exhaust is exhausted from the exhaust hole 58 to the outside of the engine cover 17 via the exhaust path 54. Be heated. For this reason, the intake air of the intake device 33 is not warmed by the heat of the exhaust, and the performance of the engine 11 can be suitably secured.

  (4) Since the other end 68 of the air introduction path 63 is connected in the middle of the exhaust path 54 extending from the ventilation fan 53 to the exhaust path 58, the rotational speed of the engine 11 decreases and the ventilation fan 53 Even if the ventilation function due to the air pressure decreases, a negative pressure is generated in the exhaust passage 42 at this time, and air is introduced from the exhaust air passage 54 through the air introduction passage 63 into the exhaust passage 42. A decrease in ventilation function due to the fan 53 can be compensated.

  (5) Since the one end 67 of the air introduction path 63 is connected to the exhaust passage 42 of the exhaust manifold 41 at a position higher than the central axis Oa of the uppermost cylinder 23A, this exhaust passage is at the negative pressure of the exhaust passage 42. Even if water intrudes into 42, this water does not reach the one end 67 of the air introduction path 63 reliably, so that the air introduction function by the air introduction path 63 can be maintained well.

  (6) Since the one end 67 of the air introduction path 63 is connected to the exhaust passage 42 of the exhaust manifold 41 at a position higher than the central axis Oa of the uppermost cylinder 23A, the exhaust passage in the event of a failure of the check valve 64 Even when water enters the inside 42, the water does not reliably reach the check valve 64 in the air introduction path 63, and the durability of the check valve 64 can be improved.

  (7) One end 67 of the air introduction path 63 is connected to the exhaust passage 42 of the exhaust manifold 41 at a position higher than the central axis Oa of the uppermost cylinder 23A, so that the air introduction connected to the exhaust air path 54 is achieved. Approach the other end 68 of the path 63. For this reason, the entire length of the air introduction path 63 is shortened, and a compact design can be realized.

  (8) Since one end 67 of the air introduction path 63 is connected to the exhaust passage 42 of the exhaust manifold 41 at a position higher than the central axis Oa of the uppermost cylinder 23A, the one end 67 of the air introduction path 63 is exhausted. The resistance of the exhaust flowing downward in the passage 42 toward the exhaust discharge port 43 is not obtained, and therefore the performance of the engine 11 can be ensured satisfactorily.

  (9) When the exhaust passage 42 of the exhaust manifold 41 has a negative pressure, the air in the exhaust passage 54 is introduced from the air introduction passage 63 into the exhaust passage 42, and the negative pressure in the exhaust passage 42 is eliminated. Since entry of water into the passage 42 is prevented, adhesion of water to the high temperature catalyst 66 disposed in the exhaust passage 42 can be avoided. As a result, damage to the catalyst 66 can be prevented.

  As a modification of the present embodiment, the one end 67 of the air introduction path 63 may be connected at a higher position in the exhaust passage 42 of the exhaust manifold 41 than the central axis Od of the lowermost cylinder 23D in a side view. Good. In this case, one end 67 of the air introduction path 63 is connected at a position close to the catalyst 66, and the air flowing through the exhaust air path 54 is introduced into the exhaust passage 42 in the vicinity of the catalyst 66. Therefore, in this modified embodiment, the following effects (10) to (12) are obtained.

  (10) Since one end 67 of the air introduction path 63 is connected to the exhaust passage 42 of the exhaust manifold 41 at a position higher than the central axis Od of the lowermost cylinder 23D, the inside of the exhaust passage 42 should be watered from below. Even in this case, even in this case, the water does not reach the one end 67 of the air introduction path 63, and the air introduction function by the air introduction path 63 can be ensured satisfactorily.

  (11) Even when water enters the exhaust passage 42 of the exhaust manifold 41 in the event of a failure of the check valve 64 provided in the air introduction passage 63, one end 67 of the air introduction passage 63 is at the bottom cylinder 23D. By connecting to the exhaust passage 42 at a position higher than the central axis Od, the water does not reach the check valve 64 even in this case, so that the durability of the check valve 64 can be improved. it can.

  (12) Since one end 67 of the air introduction path 63 is connected to the exhaust passage 42 of the exhaust manifold 61 at a position close to the catalyst 66, air is introduced into the catalyst 66 from the air introduction path 63 so that the catalyst The function of 66 can be improved and the exhaust purification performance can be improved.

[B] Second embodiment (FIG. 6)
FIG. 6 is a side view of the engine and the engine holder in the second embodiment of the outboard motor according to the present invention, partly broken and showing a check valve open state. In the second embodiment, the same parts as those in the first embodiment are denoted by the same reference numerals, and the description will be simplified or omitted.

  The outboard motor 70 of the present embodiment is different from the outboard motor 10 of the above embodiment in that the connection position of the one end 72 of the air introduction path 71 and the structure of the exhaust passage of the exhaust manifold 73 serving as an exhaust assembly portion. The arrangement position of the catalyst 66 and the like.

  That is, the exhaust manifold 73 includes a first exhaust passage 74 connected to the exhaust ports 36A, 36B, 36C, and 36D, a second exhaust passage 75 connected to the exhaust outlet 43 of the engine holder 12, and the first of these. The exhaust passage 74 and the second exhaust passage 75 are connected to each other, and a catalyst 66 is disposed in the connection passage 76. The first exhaust passage 74, the second exhaust passage 75 and the connection passage 76 are formed in the cylinder block 25, and a water jacket 77 is provided around the first exhaust passage 74 and the second exhaust passage 75 in the cylinder block 25. It is formed. The inside of the first exhaust passage 74 and the second exhaust passage 75 is cooled by the cooling water flowing in the water jacket 77.

  The connection path 76 also functions as a catalyst holding part by accommodating and arranging the catalyst 66. The connecting path 76 further arranges the catalyst 66 in the cylinder block 25 between the central axis Oa of the uppermost cylinder 23A and the central axis Od of the lowermost cylinder 23D. One end 72 of the air introduction path 71 is connected to the connection path 76 and is positioned in the vicinity of the catalyst 66. Thereby, the air in the exhaust air passage 54 introduced through the other end 68 of the air introduction passage 71 when the check valve 64 of the air introduction passage 71 is opened is directed to the catalyst 66 in the connection passage 76 as indicated by an arrow C. After being guided, the air is introduced into the first exhaust passage 74 and the second exhaust passage 75, and the negative pressure in the first exhaust passage 74, the second exhaust passage 75 and the connecting passage 76 is eliminated.

  In the present embodiment, the valve assembly 78 that houses the check valve 64 in the air introduction path 71 may be integrally formed with the connection path 76 of the air manifold 73. The valve assembly 78 includes a water jacket 79, and the check valve 64 is particularly cooled by cooling water flowing through the water jacket 79.

  Therefore, according to this embodiment, in addition to the effects (1) to (4), (10) and (11) of the first embodiment, the following effects (13) and (14) are obtained. .

  (13) One end 72 of the air introduction path 71 is connected to the connection path 76 of the exhaust manifold 73 that accommodates the catalyst 66, and air is introduced into the vicinity of the catalyst 76, whereby the function of the catalyst 66 is enhanced and the exhaust purification performance. Can be improved.

  (14) The negative pressure in the first exhaust passage 74, the second exhaust passage 75 and the connection passage 76 of the exhaust manifold 73 is eliminated by the introduction of air from the air introduction passage 71, and these exhaust passages 74 and 75 and the connection are connected. Intrusion of water into the passage 76 is prevented, and the catalyst 66 is disposed at a high position between the central axis Oa of the uppermost cylinder 23A and the central axis Od of the lowermost cylinder 23D. For these reasons, water adhesion to the catalyst 66 is reliably prevented, and the reliability of the catalyst 66 can be suitably ensured.

  As mentioned above, although this invention was demonstrated based on the said embodiment, this invention is not limited to this.

  For example, in the above-described embodiments, the other ends 68 of the air introduction paths 63 and 71 are described as being connected in the middle of the air exhaust path 54 from the ventilation fan 53 to the air exhaust hole 58 of the tilt-up handle 57. However, it may be disposed directly in the vicinity of the air exhaust hole 58 without using the air exhaust path 54. As described above, the other end 68 of the air introduction paths 63 and 71 is disposed directly in the vicinity of the air exhaust hole 58, and in particular, the check valve 64 of the air introduction paths 63 and 71 should break down and the exhaust passage 42. Even when the exhaust in the connecting passage 76 flows back into the air introduction passages 63 and 71, the exhaust can be discharged into the atmosphere from the exhaust hole 58, so that safety can be improved.

  In the first embodiment, the valve assembly that accommodates the check valve 64 in the air introduction path 63 may be configured integrally with the cylinder block 25 or the cylinder head 26. In this case, similarly to the valve assembly 78 of the second embodiment, the structure of the air introduction path 63 can be simplified, and the check valve 64 can be easily assembled. Can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a left cross-sectional view illustrating a first embodiment of an outboard motor according to the present invention, with a part thereof broken. The top view which shows the engine cover of FIG. 1 except a tilt up handle. The perspective view which shows the engine and engine holder of FIG. FIG. 4 is a side view showing the check valve closed state of the engine of FIG. FIG. 4 is a side view of the engine and the like shown in FIG. The engine and engine holder in 2nd Embodiment of the outboard motor which concern on this invention, it is a partially broken side view, and shows the open side state of a check valve.

Explanation of symbols

10 Outboard motor 11 Engine 17 Engine cover 34 Exhaust device 41 Exhaust manifold (exhaust assembly)
42 Exhaust passage 51 Flywheel magnet 53 Ventilation fan 54 Exhaust passage 57 Tilt-up handle 58 Exhaust hole 63 Air introduction passage 64 Check valve 66 Catalyst 67 One end 68 Other end 70 Outboard motor 71 Air introduction passage 72 One end 73 Exhaust manifold (Exhaust assembly)
74 1st exhaust passage 75 2nd exhaust passage 76 Connection way

Claims (6)

In outboard motors where the engine is mounted vertically and the engine is covered with an engine cover,
An exhaust part having an exhaust passage communicating with the exhaust port of the cylinder head of the engine is provided in a side part of the engine, and an exhaust hole for exhausting air warmed in the engine cover is provided in the engine cover. Formed at the top,
One end is connected to the exhaust part and the other end is connected to the vicinity of the exhaust hole, and an air introduction path for introducing air into the exhaust path when negative pressure in the exhaust path in the exhaust part is provided. Outboard motor characterized by The engine is a multi-cylinder engine, and the exhaust part is an exhaust collecting part having an exhaust passage for collecting exhaust from each exhaust port in a cylinder head of the multi-cylinder engine, and one end of the air introduction path is a side surface. The outboard motor according to claim 1, wherein the outboard motor is connected to the exhaust collecting portion at a position higher than that of the lowermost cylinder in view. 3. The outboard motor according to claim 2, wherein one end of the air introduction path is connected to the exhaust collecting portion at a position higher than the uppermost cylinder in a side view. A ventilation fan is provided on the upper part of the engine, and the other end of the air introduction path is connected to the exhaust path from the ventilation fan to the exhaust hole of the engine cover. Outboard motor as described in 2. The outboard motor according to claim 1, wherein a catalyst is disposed in the exhaust passage, and one end of an air introduction path is connected to the vicinity of the catalyst. A catalyst is disposed between the uppermost cylinder and the lowermost cylinder in a side view in the exhaust passage of the exhaust collecting portion, and one end of an air introduction path is connected to the vicinity of the catalyst. The outboard motor according to claim 2.

Images