JP2004150445A - Outboard motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To define an air discharge channel extended from an engine to a lower part, a cooling water supply channel and a water discharge channel without increasing the number of components and the man-hour for assembling, and to reduce a weight and to miniaturize an outboard motor without impairing the rigidity of the entire outboard motor. <P>SOLUTION: The air discharge channel 41 vertically penetrated through an oil pan 14 is molded integrally with the oil pan 14, an joint seating surface 86 adhered to an upper face of a drive shaft housing 15 is formed on a bottom part of the oil pan 14, and the drive shaft housing 15 is fixed to a lower part of the oil pan 14. <P>COPYRIGHT: (C)2004,JPO

Description

  The present invention relates to an outboard motor in which an oil pan is installed on a lower surface of an engine.

  An outboard motor equipped with a four-cycle type engine has an oil pan installed on the lower surface of the engine, and the oil stored in the oil pan lubricates the inside of the engine.

  As shown in Patent Literatures 1 to 3, in a conventional outboard motor, the oil pan is provided separately inside a casing (drive shaft housing) provided below the engine.

Further, in the conventional outboard motor, an exhaust passage extending downward from the engine, a coolant supply passage and a drain passage are provided near the oil pan, and these passages are each provided with a dedicated pipe member on the lower surface of the engine. Or, it was assembled in the vicinity of the oil pan by bolting it to a part that would be the base of the engine.
JP-A-4-3301212 JP-A-5-278686 JP-A-8-26188

  However, as described above, the oil pan was separately provided inside the casing, which led to an increase in the size, weight, and rigidity of the outboard motor.

  In addition, as described above, in the conventional outboard motor, the exhaust passage, the water supply passage, and the drain passage are assembled using a dedicated pipe member, so that the airtightness of the fixing bolt of each pipe member and the connection portion of the pipe member is maintained. A large number of parts such as gaskets are required, and these parts increase the number of parts, increase the number of assembly steps due to the complicated structure, increase the manufacturing cost, and this also leads to an increase in the weight of the outboard motor.

  Further, there is a serious problem that oil stored in the oil pan is heated by heat of exhaust gas flowing in an exhaust passage provided in the vicinity of the oil pan, and the service life and lubrication performance of the oil are likely to deteriorate. Was. Not only that, the bolts that fix the pipe members that make up the exhaust passage to the lower surface of the engine and the parts that serve as the base are damaged due to the heat of the exhaust gas, and the materials are degraded or adhered to breakage. was there.

  The outboard motor according to the present invention has been invented in order to solve these problems, and its object is to reduce the number of parts and the number of assembling steps without increasing the number of parts and the exhaust structure extending downward from the engine by a lightweight structure. An object of the present invention is to make it possible to install a passage, a cooling water supply passage and a drain passage, and to reduce the weight and reduce the size of the outboard motor without impairing the rigidity of the entire outboard motor.

  A further object of the outboard motor according to the present invention is to prevent the oil stored in the oil pan from being affected by exhaust heat, thereby extending the life of the oil, preventing deterioration of lubrication performance, and keeping the oil warm. The purpose is to improve lubrication performance by improving lubricity.

  To achieve the above object, an outboard motor according to the present invention, as described in claim 1, is characterized in that a water-cooled four-stroke engine covered with an engine cover that can be divided into upper and lower parts is vertically oriented with its crankshaft directed vertically. The exhaust gas from the engine passes through the vicinity of the oil pan installed on the lower surface of the engine, passes through the internal space of the drive shaft housing, passes through the exhaust passage inside the gear housing installed under the drive shaft housing, and the center of the propeller In the outboard motor configured to be discharged into the water from the part, the exhaust passage penetrating the inside of the oil pan in the vertical direction is integrally formed with the oil pan, and the bottom of the oil pan is joined to the upper surface of the drive shaft housing. And the drive shaft housing is fixed to the lower part of the oil pan. That.

  Further, as described in claim 2, a water supply passage and a drainage passage are formed integrally with the oil pan, and a water supply passage and a drainage passage are formed so as to surround the exhaust passage.

  Further, as set forth in claim 3, a vertical wall is formed inside the drive shaft housing along a shape of a joint seat surface with the oil pan, and the exhaust chamber communicates with a lower end of an exhaust passage formed in the oil pan. Is provided.

  According to a fourth aspect of the present invention, an insertion opening of the drive shaft connected to the lower end of the crankshaft is formed at the front end of the oil pan.

  As described in claim 5, the periphery of the oil pan is covered with a lower cover of an engine cover.

  According to the configuration of the first aspect, it is not necessary to install the exhaust passage using a dedicated pipe member as in the related art, and there is no need for any components such as the pipe member, fixing bolts for fastening the pipe member, and gaskets for maintaining airtightness. Therefore, the exhaust passage can be installed with a very simple and lightweight structure without increasing the number of parts and the number of assembly steps. Moreover, since the oil pan itself is a strength structural member of the outboard motor, it does not impair the rigidity of the entire outboard motor as compared with a conventional case in which the oil pan is separately provided inside the drive shaft housing. Weight reduction and compactness can be achieved.

  According to the configuration of claim 2, the water supply passage and the drainage passage can be installed with a very simple and lightweight structure without increasing the number of parts and the number of assembly steps, and the exhaust water is exhausted by the cooling water flowing through the water supply passage and the drainage passage. Since the heat of the exhaust gas flowing in the passage is shielded from the oil stored in the oil pan, the oil is not affected by the exhaust heat, and the oil life and the lubrication performance can be prevented from deteriorating. In addition, the vertical and horizontal wall structures of the water supply passage and the drain passage formed integrally with the oil pan together with the exhaust passage can increase the strength of the oil pan and thus the rigidity of the entire outboard motor.

  According to the configuration of the third aspect, the drive shaft housing can be strengthened to increase the rigidity of the outboard motor.

  According to the configuration of the fourth aspect, the oil pan can be further strengthened and the rigidity of the outboard motor can be increased.

  According to the configuration of the fifth aspect, the lubricating performance can be improved by improving the heat retaining property of the oil.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a left side view showing an example of an outboard motor according to the present invention.

  The outboard motor 1 is mounted on a transom 3 of a hull 2 via a clamp bracket 4, and is rotatable left and right around a swivel shaft 5 provided vertically at a rear portion of the clamp bracket 4.

  The engine 6 mounted on the uppermost part of the outboard motor 1 is, for example, an in-line four-cylinder water-cooled four-stroke gasoline engine, and is mounted vertically so that its crankshaft 7 is oriented vertically. The engine 6 is assembled such that components such as a crankcase 9, a cylinder block 10, a cylinder head 11, and a head cover 12 are connected in the front-rear direction.

  An oil pan 14 is fixed to a lower portion of the engine 6 via a thick plate-shaped engine holder 13. A drive shaft housing 15 is fixed to a lower portion of the oil pan 14, and a gear housing 16 is further fixed to a lower portion of the oil pan 14. I have.

  The parts of the engine 6, the engine holder 13 and the oil pan 14 are covered with an engine cover 18 which can be divided into upper and lower parts. The engine cover 18 includes a lower cover 18a fixed so as to straddle the engine holder 13 and the oil pan 14, and an upper cover 18b detachably mounted thereon. Work and the like are performed by removing the upper cover 18b.

  A lower drive shaft 19 is connected to the lower end of the crankshaft 7 of the engine 6 so as to rotate integrally therewith. The drive shaft 19 penetrates through the engine holder 13, the oil pan 14, and the drive shaft housing 15 to form a gear housing. Has reached within 16.

  On the other hand, a propeller shaft 20 extending forward and backward is supported in the gear housing 16, and a propeller 21 is provided at the rear end thereof so as to rotate integrally therewith. The rotation of the drive shaft 19 is transmitted to the propeller shaft 20 by a bevel gear mechanism 22 provided at the intersection of the drive shaft 19 and the propeller shaft 20, and the propeller 21 is driven to rotate.

  At the front edges of the engine holder 13 and the drive shaft housing 15, a pair of left and right mounts 23 and 24 are provided, respectively, and the upper and lower mounts 23 and 24 are supported on the upper and lower ends of the swivel shaft 5, respectively. Is done.

  An intake device 26 is mounted on the left side of the engine 6, and a starter motor 27 for starting is installed on the front side. The upper end of the crankshaft 7 protrudes above the upper surface of the engine 6, and a flywheel 28 is provided integrally with this portion, and a drive pulley 29 is provided below the flywheel 28.

  On the other hand, a camshaft 30 parallel to the crankshaft 7 is rotatably supported inside the cylinder head 11, and an upper end portion thereof protrudes from the upper surface of the engine 6, and a driven pulley 31 is integrally provided on this protruding portion. I have.

  A timing belt 32 is wound between a drive pulley 29 of the crankshaft 7 and a driven pulley 31 of the camshaft 30. The rotation of the crankshaft 7 is transmitted to the camshaft 30 via the timing belt 32, and It is configured such that a valve operating device (not shown) accommodated in the inside of the valve 11 operates.

  A ring gear 28a is provided in a flange shape around the flywheel 28. When the starter motor 27 is turned on, the pinion gear 27a of the starter motor 27 projects upward and meshes with the ring gear 28a, and the crankshaft 7 is driven to rotate. The engine 6 is started.

  The starter motor 27, the flywheel 28, the drive pulley 29, the driven pulley 31, the timing belt 32, and other members are covered from above by a cover member 33 made of a synthetic resin or the like, and water droplets and the like that fall from above are covered. Each part is shielded by the member 33 to ensure waterproofness.

  By the way, a water pump 35 is installed on the upper surface of the gear housing 16, and the drive shaft of the water pump 35 also serves as the drive shaft 19. A water intake 36 is provided on a side surface of the gear housing 16, and a water intake passage 37 formed to extend upward from the water intake 36 is connected to the water pump 35. The upper end of a water supply pipe 38 extending upward from the water pump 35 is connected to the lower surface of the oil pan 14.

  2 is a left side view of the oil pan 14, and FIGS. 3 and 4 are a top view and a bottom view of the oil pan 14, respectively. FIG. 5 is a longitudinal sectional view of the oil pan 14 taken along the line VV in FIG. FIG. 6 is a bottom view of the engine holder 13.

  Most of the internal space of the oil pan 14 is occupied by the oil storage tank 40. For example, an exhaust passage 41, a water supply passage 42, and a drain passage 43 are formed in a portion on the right side inside the oil pan 14. These passages 41, 42, 43 extend downward from the engine 6 and penetrate the oil pan 14 in the vertical direction. The oil pan 14 is formed by forming vertical walls 14 a, 14 b, 14 c inside the oil pan 14. It is integrally molded with 14.

  As shown in FIGS. 3 to 5, the water supply passage 42 and the drain passage 43 are formed so as to surround the exhaust passage 41. For example, the water supply passage 42 is formed in a substantially L-shape in plan view, and the exhaust passage 41 is arranged inside the L-shaped corner portion, and the drain passage 43 is arranged in front of the exhaust passage 41.

  A water supply joint 44 is provided at the bottom of the water supply passage 42, to which the upper end of the water supply pipe 38 extending from the water pump 35 is connected. An oil drain port 45 for discharging the oil in the oil storage tank 40 is provided at a lower portion on the left side of the oil pan 14.

  Further, as shown in FIG. 6, an exhaust hole 46, a water supply hole 47, and a drain hole 48 are formed in the engine holder 13 so as to match the exhaust passage 41, the water supply passage 42, and the drain passage 43 of the oil pan 14. . Drive shaft insertion ports 49, 50 through which the drive shaft 19 is inserted are formed at the front ends of the engine holder 13 and the oil pan 14. Further, a pair of left and right mount pedestals 51, 51 is provided at a front portion of the engine holder 13, and the mount portion 23 is attached thereto.

  FIGS. 7 and 8 are longitudinal sectional views of the engine 6 and the like along the lines VII-VII and VIII-VIII in FIG. 1, respectively. As shown in FIG. 7, four intake ports 53 are open on the left side of the cylinder head 11 of the engine 6, and four exhaust ports 54 are open on the right side. Each of the intake ports 53 is connected to the four intake branches 26a of the intake device 26 described above, and the exhaust port 54 is fixed with an exhaust manifold 55.

  An exhaust collecting passage 56 is formed inside the exhaust manifold 55, and the exhaust ports 54 are gathered in the exhaust collecting passage 56. The lower end of the exhaust manifold 55 overlaps the right side surface of the engine holder 13, and the lowermost end of the exhaust collecting passage 56 is curved toward the engine holder 13 and connects to the above-described exhaust hole 46 opened on the left side surface of the engine holder 13. Therefore, an exhaust path is configured in the order of the exhaust port 54, the exhaust collecting passage 56, the exhaust hole 46, and the exhaust passage 41.

  An exhaust water jacket 58 through which cooling water flows is formed around the exhaust collecting passage 56. An inlet 59 is provided at the lowermost portion of the exhaust water jacket 58, and an outlet 60 is provided at the uppermost portion. A pressure valve 61 is provided inside the outlet 60. A water detection hole 62 is provided at the lowermost part of the exhaust water jacket 58.

  On the other hand, as shown in FIG. 8, four cylinders 64 are formed inside the cylinder block 10, and a block water jacket 65 through which cooling water flows is formed so as to surround the periphery thereof. An inlet 66 is provided at the lowermost part of the block water jacket 65, and an outlet 67 is provided at the uppermost part. A thermostat 68 is installed inside the outlet 67.

  The respective inlets 59 and 66 of the exhaust water jacket 58 and the block water jacket 65 are connected to the water supply passage 42 of the oil pan 14 via the water supply holes 47 of the engine holder 13, respectively. Drain hoses 70 and 71 are connected to the outlets 60 and 67, respectively. The other ends of the drain hoses 70 and 71 are joined to a drain hose 73 by a T-shaped joint 72, and the drain hose 73 is connected to an L-shaped joint. The oil pan 14 is connected to the drain hole 48 of the engine holder 13 via 74, and is connected to the drain passage 43 of the oil pan 14 from here.

  Therefore, a cooling water path as shown in FIG. 9 is configured. As shown in this figure, the block water jacket 65 communicates with a head water jacket 75 formed in the cylinder head 11, so that cooling water flows through each other. A cylinder wall temperature sensor is provided between the block water jacket 65 and the thermostat 68.

  When the engine 6 operates, the water pump 35 is driven by the rotation of the drive shaft 19, and external water is taken in as cooling water from the intake port 36 of the gear housing 16 and flows along the cooling water path in FIG. The jacket 58, the block water jacket 65, and the head water jacket 75 are cooled.

  The thermostat 68 is closed when the engine 6 is cold. When the temperature of the cooling water inside the block water jacket 65 and the head water jacket 75 reaches a predetermined value after the engine 6 starts, the thermostat 68 opens to open the cooling water. Is distributed. For this reason, the warm-up time of the engine 6 is reduced, and the cylinder 64 is prevented from being excessively cooled during operation.

  When the thermostat 68 is closed, the pressure downstream of the water pump 35 increases more than necessary, so that the pressure valve 76 shown in the cooling water path of FIG. Water) escapes to protect the cooling water path.

  As shown in FIGS. 2 to 5, a flush passage 77 extending horizontally from the left side surface of the oil pan 14 to the right and communicating with the bottom of the water supply passage 42 is formed at the bottom of the oil pan 14. A short valve passage 78 extending downward is formed in the middle of the passage 77, and a pressure valve 76 is fixed to a valve pedestal 79 formed at an outer end of the valve passage 78 with a bolt 80 or the like (see FIG. 5).

  By the way, the entrance portion of the flash passage 77 is enlarged to form a flash port 81. The flash port 81 is plugged with a plug 82 (see FIGS. 1 and 5) detachably screwed in and closed. If the plug 82 is removed and a water hose is inserted into the flush port 81, the entire cooling water path can be easily washed with fresh water.

  The periphery of the oil pan 14 is covered with a lower cover 18a of the engine cover 18. As shown in FIG. 5, a flash hole 84 is formed at a position corresponding to the flash port 81 of the lower cover 18a. The plug 82 closing the flash port 81 by the hole 84 is exposed to the outside.

  As shown in FIG. 4, a flat joint seat surface 86 is formed on the bottom of the oil pan 14 to be joined to the upper surface of the drive shaft housing 15, and as shown in FIG. A joining seat surface 87 joined to the joining seat surface 86 of the oil pan 14 is formed. Vertical walls 15a, 15b, 15c are formed inside the drive shaft housing 15 along the shapes of the joint seat surfaces 86, 87.

  The internal space of the drive shaft housing 15 is partitioned into a main exhaust chamber 88, an exhaust release chamber 89, and a pressure valve chamber 90 by these vertical walls 15a, 15b, 15c. The lower end of an exhaust passage 41 formed in the oil pan 14 communicates with the main exhaust chamber 88. The lower portion of the main exhaust chamber 88 is connected to the inside of the gear housing 16 and communicates with the inside of the gear housing 16 and an exhaust outlet passage 91 (see FIG. 1) formed at the center of the propeller 21.

  On the other hand, a small notch 92 is formed at the upper end of the vertical wall 15a that defines the exhaust release chamber 89, and the exhaust release chamber 89 communicates with the main exhaust chamber 88 by this notch 92. Further, the exhaust release chamber 89 communicates with the outside through an exhaust release passage 93 formed on the lower surface of the oil pan 14. At the bottom of the exhaust release chamber 89 and the pressure valve chamber 90, openings 94 and 95 communicating with the main exhaust chamber 88 are formed.

  Further, a drive shaft insertion opening 96 through which the drive shaft 19 is inserted is formed at the front end of the drive shaft housing 15, and mount pedestals 97, 97 are provided on the lower left and right side surfaces of the drive shaft housing 15, and the drive seats 97 are provided here. The mounting unit 24 is attached.

  The exhaust gas of the engine 6 flows from the exhaust passage 41 of the oil pan 14 to the main exhaust chamber 88 of the drive shaft housing 15. During idling operation and low-speed operation of the engine 6, the exhaust gas enters the exhaust release chamber 89 through the notch 92 from the main exhaust chamber 88 because water is contained in the main exhaust chamber 88 and the amount of exhaust gas is small. From there, it is discharged outside through an exhaust release passage 93.

  In addition, when the engine 6 is operated at medium to high speeds, the rotation of the propeller 21 causes the water in the main exhaust chamber 88 to be sucked out and the water level to drop, so that the exhaust gas discharge resistance is reduced and the amount of exhaust gas is increased. Therefore, most of the exhaust gas is discharged into the water from the center of the propeller 21 through the exhaust outlet passage 91 of the gear housing 16 after being expanded in the main exhaust chamber 88.

  The pressure valve chamber 90 surrounds the pressure valve 76 provided on the lower surface of the bottom of the oil pan 14. Therefore, the drainage from the pressure valve 76 flows downward in the pressure valve chamber 90, exits the opening 95, and is discharged to the outside via the exhaust outlet passage 91.

  The outboard motor 1 is configured as described above.

  In the outboard motor 1, the exhaust passage 41 extending downward from the engine 6, the cooling water supply passage 42 and the drain passage 43 are integrally formed with the oil pan 14. It is not necessary to install the passage, the water supply passage, and the drain passage using a dedicated pipe member. Therefore, parts such as pipe members, fixing bolts for fastening the pipe members, and gaskets for maintaining airtightness are not required at all, and the exhaust passage 41 and the exhaust passage 41 are formed with a very simple and lightweight structure without increasing the number of parts and the number of assembly steps. A water supply passage 42 and a drain passage 43 can be provided. In addition, since the oil pan 14 is formed by a die casting method, it is not necessary to provide a core for forming the passages 41, 42, and 43 in a mold for molding the oil pan 14, thereby increasing the cost of the mold. No worries.

  In this outboard motor 1, the drive shaft housing 15 is fixed below the oil pan 14, so that the oil pan 14 itself is a strength structural member of the outboard motor 1. For this reason, as compared with the case where the oil pan 14 is separately provided inside the drive shaft housing 15 as in the conventional case, the weight of the outboard motor 1 can be reduced and the size of the outboard motor 1 can be reduced without reducing the rigidity of the entire outboard motor 1. Can be planned.

  The rigidity of the oil pan 14 is greatly improved by vertical and horizontal wall structures such as an exhaust passage 41, a water supply passage 42, a drain passage 43, and a drive shaft insertion port 50 integrally formed therein. The overall rigidity can be effectively increased.

  Further, since the water supply passage 42 and the drain passage 43 are formed so as to surround the exhaust passage 41, the heat of the high-temperature exhaust gas flowing in the exhaust passage 41 by the cooling water flowing through the water supply passage 42 and the drain passage 43 reduces the oil. The oil stored in the pan 14 is completely shielded from the oil. For this reason, the influence of the exhaust heat does not affect the oil, and deterioration of the oil life and lubrication performance can be prevented.

  In addition, since the periphery of the oil pan 14 is covered with the lower cover 18a of the engine cover 18, it is possible to improve the lubricating performance and the starting performance by improving the heat retaining property of the oil in cold weather or the like.

  On the other hand, since the vertical walls 15a, 15b, 15c are formed inside the drive shaft housing 15 along the shape of the joint seat surfaces 86, 87 with the oil pan 14, the drive shaft housing 15 is strengthened and the outboard motor 1 is strengthened. Can be further increased in rigidity.

  Further, in this outboard motor 1, since the pressure valve 76 for adjusting the water pressure of the cooling water path is provided at the bottom of the oil pan 14, the pressure valve 76 is located immediately downstream of the water pump 35 in the cooling water path. It is located in. Therefore, even if the water pressure from the water pump 35 rises more than necessary, excess water pressure is released from the pressure valve, and the water pressure in the entire cooling water path does not rise more than necessary, reducing the burden on the gaskets provided in each part. Thus, leakage of the cooling water can be prevented. In addition, when the engine 6 is cold started, excess cooling water is not supplied to the cooling water path, so that warm-up performance is improved.

  Moreover, the pressure valve 76 is provided on the lower surface side of the bottom of the oil pan 14, and the drive shaft housing 15 fixed to the lower surface of the oil pan 14 surrounds the pressure valve 76, and the drainage from the pressure valve 76 flows downward. Since the valve chamber 90 is provided, exhaust gas flowing through the main exhaust chamber 88 inside the drive shaft housing 15 does not directly hit the pressure valve 76. Therefore, the pressure valve 76 itself and the sealing rubber parts and gaskets used in the pressure valve 76 can be protected from the exhaust gas, and the flow of the water discharged from the pressure valve 76 is hindered by the exhaust gas. Since the pressure valve disappears, the performance of the pressure valve 76 can be sufficiently exhibited.

  Further, in this outboard motor 1, a flush port 81 for washing the cooling water path is provided on the outer surface of the oil pan 14, and a plug 82 closing the flush port 81 is exposed to the outside. There is no need to provide piping or the like connected to the flash port 81, and the structure around the flash port 81 can be simplified. Moreover, since the cleaning operation of the cooling water path can be started immediately by removing the plug 82 exposed to the outside, the workability at the time of cleaning is greatly improved.

The left view which shows an example of the outboard motor which concerns on this invention. The left view of an oil pan. The top view of the oil pan which shows one Embodiment of this invention. The bottom view of an oil pan. FIG. 5 is a vertical sectional view of the oil pan along the line V-V in FIG. 3. The bottom view of an engine holder. FIG. 2 is a longitudinal sectional view of the engine and the like along the line VII-VII in FIG. 1. FIG. 8 is a longitudinal sectional view of the engine and the like along the line VIII-VIII in FIG. 1. FIG. 3 is a block diagram showing a cooling water path. FIG. 4 is a perspective view of the drive shaft housing as viewed from diagonally upper left.

Explanation of reference numerals

1 Outboard motor 6 Engine 7 Crankshaft
14 Oil pan
15 Drive shaft housing
15a, 15b, 15c Vertical wall
16 Gear housing
18 Engine cover
18a Lower cover
21 propeller
41 Exhaust passage
42 Water supply passage
43 Drainage passage
50 Drive shaft insertion port
86, 87 Joint bearing surface
88 Main exhaust chamber
91 Exhaust outlet passage

Claims (5)

A water-cooled 4-stroke engine covered with an engine cover that can be split up and down is mounted vertically with the crankshaft facing vertically, and exhaust gas from the engine passes through the vicinity of an oil pan installed on the underside of the engine and the drive shaft In an outboard motor configured to be discharged into the water from the center of the propeller through the exhaust passage inside the gear housing installed at the lower part of the drive shaft housing through the housing internal space, the outboard motor penetrates vertically inside the oil pan A ship having an exhaust passage formed integrally with an oil pan, a joining seat surface joined to an upper surface of a drive shaft housing formed at a bottom portion of the oil pan, and the drive shaft housing fixed to a lower portion of the oil pan. Outside machine. 2. The outboard motor according to claim 1, wherein a water supply passage and a drain passage are formed integrally with the oil pan, and a water supply passage and a drain passage are formed so as to surround the exhaust passage. 2. The outboard boat according to claim 1, wherein a vertical wall is formed in the drive shaft housing so as to be partitioned along a shape of a joint seat surface with the oil pan, and an exhaust chamber communicating with a lower end of an exhaust passage formed in the oil pan is provided. Machine. The outboard motor according to claim 1, wherein an insertion port of a drive shaft connected to a lower end of the crankshaft is formed at a front end of the oil pan. The outboard motor according to claim 1, wherein a periphery of the oil pan is covered with a lower cover of an engine cover.

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