Patent Description:
The prior art document <CIT> or the prior art document <CIT> discloses an outboard motor with an engine, a drive shaft extending in a first direction from the engine, a propeller shaft extending in a direction intersecting with the drive shaft, a housing configured to accommodate the engine, the drive shaft, and the propeller shaft and includes at least one discharge portion. The discharge portion discharging exhaust gas. A discharge passage is configured to guide the exhaust gas from the engine to the discharge portion inside the housing. A non-metal cover member is detachably attached to the housing so as to cover the discharge portion and includes an exhaust hollow. Prior art document <CIT> discloses an outboard motor that includes an engine support member, an engine, an upper casing, a lower casing, a propeller, and an engine cover. On the engine support member, the engine is mounted. The engine cover covers the engine. A crankshaft of the engine is arranged so as to penetrate through the engine in the up-down direction. A drive shaft extends along the up-down direction from the lower end of the engine. The lower end of the drive shaft is coupled to a propeller shaft via a forward-reverse switching mechanism. The propeller rotates integrally with the propeller shaft. Portions in which an exhaust pipe and a pilot water pipe of the engine are exposed of the rear surface of the engine cover are exposed to exhaust gas exhausted from the exhaust pipe and stained with, for example, carbon. In addition, the exposed portions are stained with seawater flowing out from the pilot water pipe and whitened by salt. The exhaust pipe and the pilot water pipe are provided close to each other, such that the area to be stained on the engine cover is small. Moreover, as a prior art, an outboard motor, which includes a discharge passage for guiding exhaust gas and cooling water from an engine, is disclosed (see <CIT>). In this type of outboard motor, generally, an exhaust hollow for discharging the above exhaust gas from the discharge passage to the outside is provided directly on a housing. For example, the exhaust hollow is a hole which penetrates the housing from the inside of the housing to the outside of the housing.

In the conventional outboard motor, the hole penetrating the housing is used as the exhaust hollow for discharging the exhaust gas which is discharged from the engine. In this case, fuel, which is contained in the exhaust gas discharged from the exhaust hollow, may adhere to an outer surface around the exhaust hollow of the housing and discolor the outer surface of the housing. In particular, if the housing is made of metal and the exhaust gas includes nitrogen oxide, the nitrogen oxide may oxidize the outer surface around the exhaust hollow of the housing and discolor the outer surface of the housing.

An object of the present invention is to provide an outboard motor which is capable of suppressing discoloration around an exhaust hollow. According to the present invention said object is solved by an outboard motor having the features of independent claim <NUM>. Preferred embodiments are laid down in the dependent claims.

The outboard motor according to one aspect includes an engine, a drive shaft, a propeller shaft, a housing, a discharge passage, and a pair of non-metal cover members. The drive shaft extends in a first direction from the engine. The propeller shaft extends in a direction intersecting with the drive shaft. The housing is configured to accommodate the engine, the drive shaft, and the propeller shaft. The housing includes at least a pair of discharge portions. The discharge portions discharges exhaust gas and cooling water of the engine. The discharge passage is configured to guide the exhaust gas and the cooling water from the engine to the discharge portions inside the housing. At least a pair of non-metal cover members is detachably attached to the housing so as to cover the discharge portion. The non-metal cover members include at least one exhaust hollow.

In the present invention, an outboard motor is capable of suppressing discoloration around an exhaust hollow.

The following embodiments will be described with reference to the drawings. As shown in <FIG>, the watercraft <NUM> includes a hull <NUM> and an outboard motor <NUM>. In this embodiment, an example, in which the number of the outboard motor <NUM> is one, is described. The number of the outboard motor <NUM> may be plural.

In the following description, direction of each of front, rear, left, right, up, and down means direction of each of front, rear, left, right, up, and down of the hull <NUM>. For example, as shown in <FIG>, the center line C1 extending in a front-rear direction of the hull <NUM> passes through a center of gravity G of the hull <NUM>.

The front-back direction is a direction along the center line C1. The front is an upward direction toward an upper side along the center line C1 of <FIG>. The rear is a downward direction along the center line C1 of <FIG>. In this embodiment, the front-rear direction of the outboard motor <NUM> is defined by an attitude of the hull <NUM> (an attitude of <FIG>) when the outboard motor <NUM> moves the hull <NUM> in the front-rear direction. The left-right direction of <FIG> corresponds to the front-rear direction of the outboard motor <NUM>.

The left-right direction (a width direction) is a direction perpendicular to the center line C1 in FIG. A left side is a direction perpendicular to the center line C1 of <FIG> and the direction toward a left side. A right side is a direction perpendicular to the center line C1 of <FIG> and the direction toward the right side. A vertical direction is a direction perpendicular to the front-back direction and the left-right direction.

As shown in <FIG>, the outboard motor <NUM> generates a propulsive force for propelling the hull <NUM>. The outboard motor <NUM> is attached to a stern of the hull <NUM>. The outboard motor <NUM> includes an engine <NUM>, a drive shaft <NUM>, a propeller shaft <NUM>, a housing <NUM>, a discharge passage P (see <FIG>), and a pair of cover members <NUM>, <NUM>. The outboard motor <NUM> further includes a seal member <NUM> (see <FIG>). The outboard motor <NUM> further includes a shift mechanism <NUM> and a bracket <NUM>.

The pair of cover members <NUM>, <NUM> are provided on both side surfaces of the housing <NUM> respectively. <FIG> shows the cover member <NUM> which is disposed on a side surface of the housing <NUM>. The cover member <NUM> is disposed on the opposite side of the cover member <NUM>. A reference numeral of the cover member <NUM> are shown in parentheses in <FIG>. In the following, when the reference numeral of one member of a pair of members is shown, the reference numeral of the other member of the pair of members is shown in the parentheses.

The engine <NUM> is a power source that produces the propulsive force of the hull <NUM>. The engine <NUM> is disposed in the engine cover <NUM>. The engine <NUM> includes a crankshaft <NUM>. The crankshaft <NUM> extends in the vertical direction.

The engine <NUM> is connected to the drive shaft <NUM>. The drive shaft <NUM> extends in the vertical direction. For example, the drive shaft <NUM> extends downward (an example of "in a first direction") from the engine <NUM>. The propeller shaft <NUM> extends in a direction intersecting the drive shaft <NUM>. In this embodiment, the propeller shaft <NUM> extends in the front-rear direction. The propeller shaft <NUM> is connected to the drive shaft <NUM> via the shift mechanism <NUM>. A propeller <NUM> is connected to the propeller shaft <NUM>.

The shift mechanism <NUM> is driven by a shift actuator <NUM> via the shift member <NUM>. The shift mechanism <NUM> switches a rotation direction of the power which is transmitted from the drive shaft <NUM> to the propeller shaft <NUM>. Thereby, the rotation direction of the propeller <NUM> is switched to a forward direction in which the hull <NUM> moves forward or a reverse direction in which the hull <NUM> moves backward.

The bracket <NUM> is used for attaching the outboard motor <NUM> to the hull <NUM>. The outboard motor <NUM> is detachably fixed to the stern of the watercraft <NUM> via the bracket <NUM>. The bracket <NUM> includes a steering shaft <NUM>. The outboard motor <NUM> is rotatably supported by the bracket <NUM> about the steering shaft <NUM>.

As shown in <FIG>, the housing <NUM> accommodates the engine <NUM>, the drive shaft <NUM>, and the propeller shaft <NUM>. Specifically, the housing <NUM> houses the engine <NUM>, the drive shaft <NUM>, the propeller shaft <NUM>, and the shift mechanism <NUM>. The housing <NUM> includes a discharge portion <NUM> (see <FIG>) which discharges an exhaust gas of the engine <NUM> and a cooling water of the engine <NUM>. Specifically, the housing <NUM> includes the engine cover <NUM>, a housing body <NUM>, the discharge portion <NUM> (see <FIG>), and a cover arrangement portion <NUM> (see <FIG>).

The engine cover <NUM> covers the engine <NUM>. The engine <NUM> is disposed inside the engine cover <NUM>. The engine cover <NUM> is a metal member. The engine cover <NUM> may be a resin member.

The housing body <NUM> is disposed below the engine cover <NUM>. The drive shaft <NUM>, the propeller shaft <NUM>, and the shift mechanism <NUM> are disposed inside the housing body <NUM>. The housing body <NUM> is a metal member. The housing body <NUM> may be a resin member.

A cavitation plate <NUM> is provided on the housing body <NUM>. For example, the cavitation plate <NUM> is provided on the housing body <NUM> above the propeller <NUM>. Specifically, the cavitation plate <NUM> is provided on the housing body <NUM> in the vertical direction between the propeller <NUM> and the engine <NUM>.

As shown in <FIG>, the housing body <NUM> includes a wall portion <NUM> which is used for forming the discharge passage P. For example, the wall portion <NUM> of the passage is integrally formed on the inner surface of the housing body <NUM>. The housing body <NUM> further includes both side portions 31a, 31b which form a discharge chamber R (see <FIG>) described later.

As shown in <FIG>, the discharge portion <NUM> includes a pair of discharge portions <NUM>, <NUM>. The pair of discharge portions <NUM>, <NUM> discharge the exhaust gas and the cooling water discharged from the engine <NUM>. The pair of discharge portions <NUM>, <NUM> are provided in the housing <NUM>. For example, the pair of discharge portions <NUM>, <NUM> are provided in the housing body <NUM> between the engine <NUM> and the cavitation plate <NUM>.

The pair of discharge portions <NUM>, <NUM> are respectively provided on the both side portions 31a, 31b of the housing body <NUM>. For example, the pair of discharge portions <NUM>, <NUM> are respectively provided on the both side portions 31a, 31b of the housing body <NUM> so as to face each other in the width direction (left-right direction).

As shown in <FIG>, each of the pair of discharge portions <NUM>, <NUM> is a hollow portion. For example, each of the pair of discharge portions <NUM>, <NUM> is a rectangular hollow portion. Each of the pair of discharge portions <NUM>, <NUM> penetrates the housing body <NUM> from an inside of the housing body <NUM> toward an outside of the housing body <NUM>. For example, each of the pair of discharge portions <NUM>, <NUM> penetrates each of the side portions 31a, 31b which forms the discharge chamber R (see <FIG>).

As shown in <FIG>, the cover arrangement portion <NUM> includes a pair of cover arrangement portions <NUM>, <NUM>. The pair of cover members <NUM>, <NUM> are respectively disposed on the pair of cover arrangement portions <NUM>, <NUM>. The pair of cover arrangement portions <NUM>, <NUM> are provided on the housing body <NUM>.

Each of the pair of cover arrangement portions <NUM>, <NUM> is formed in a concave shape. The pair of discharge portions <NUM>, <NUM> are respectively provided on the pair of cover arrangement portions <NUM>, <NUM>. For example, as shown in <FIG>, the pair of discharge portions <NUM>, <NUM> are respectively provided on bottom portions 38a, 39a of the pair of cover arrangement portions <NUM>, <NUM>.

A positioning recess 38b (an example of a second recess portion) is provided on one of the pair of cover arrangement portions <NUM>, <NUM>. In this embodiment, an example in which the positioning recess 38b is provided on the bottom portion 38a of the cover arrangement portion <NUM> is described. A second positioning protruded portion <NUM> (described later) of the cover member <NUM> is disposed in the positioning recess 38b.

As shown in <FIG>, the discharge passage P guides the exhaust gas and the cooling water from the engine <NUM> toward the pair of discharge portions <NUM>, <NUM> in the housing <NUM>. The discharge passage P is formed by the housing <NUM>. For example, the discharge passage P is formed by the wall portion <NUM> of the passage.

The discharge passage P includes the discharge chamber R, an exhaust passage P1 (an example of a first passage), and a cooling water passage P2 (an example of a second passage).

The discharge chamber R guides the exhaust gas and the cooling water toward the pair of discharge portions <NUM>, <NUM>. The discharge chamber R is a space which is provided in the housing body <NUM> to discharge the exhaust gas and the cooling water from the pair of discharge portions <NUM>, <NUM>. Specifically, the discharge chamber R is a space which is provided in the housing body <NUM> to discharge the exhaust gas and cooling water from the discharge portions <NUM>, <NUM> and exhaust hollows 16b, 17b (described later) of the cover members <NUM>, <NUM>.

The discharge chamber R is provided inside the housing body <NUM> between the engine <NUM> and the cavitation plate <NUM>. The discharge chamber R is formed by the housing body <NUM>. For example, the discharge chamber R is formed by the both side portions 31a, 31b of the housing body <NUM> and wall portions 31c of the discharge chamber R.

The wall portions 31c of the discharge chamber R are provided on the inner surfaces of the both side portions 31a, 31b. The both side portions 31a, 31b of the housing body <NUM> include side walls of the discharge chamber R. The wall portions 31c of the discharge chamber R include a front wall of the discharge chamber R, an upper wall of the discharge chamber R, a lower wall of the discharge chamber R, and a rear wall of the discharge chamber R.

The exhaust passage P1 guides the exhaust gas, which is discharged from the engine <NUM>, from the engine <NUM> toward the discharge chamber R. The exhaust passage P1 is connected to the discharge chamber R. For example, the exhaust passage P1 is formed by wall portions 37a for the exhaust gas which are provided on the inner surface of the housing <NUM> (the housing body <NUM>). The exhaust passage P1 extends downward from the engine <NUM> and is connected to the discharge chamber R. The exhaust gas is discharged from the discharge chamber R to the outside of the housing <NUM> (the housing body <NUM>) through the discharge portions <NUM>, <NUM> and the exhaust hollow 16b, 17b of the cover members <NUM>, <NUM>.

Further, the exhaust passage P1 guides the exhaust gas to the rear portion of the propeller <NUM>. The exhaust passage P1 is connected to a space which is formed in a supporting portion of the housing <NUM> (housing body <NUM>) which supports the propeller <NUM>.

The cooling water passage P2 guides the cooling water, which is used for cooling the engine <NUM>, from the engine <NUM> toward the discharge chamber R. The cooling water passage P2 is connected to the discharge chamber R. For example, the cooling water passage P2 is formed by wall portions 37b for the cooling water which are provided on the inner surface of the housing <NUM> (the housing body <NUM>). The cooling water passage P2 extends downward from the engine <NUM> and is connected to the discharge chamber R. The cooling water is discharged from the discharge chamber R to the outside of the housing <NUM> (the housing body <NUM>) through the discharge portions <NUM>, <NUM> and the exhaust hollow 16b, 17b of the cover members <NUM>, <NUM>.

As shown in <FIG>, the seal member <NUM> includes a plurality of seal members 18a, 18b, for example, two seal members 18a, 18b. The seal members 18a, 18b are respectively disposed between the housing <NUM> and the cover members <NUM>, <NUM>. For example, the seal members 18a, 18b are respectively disposed between the cover arrangement portions <NUM>, <NUM> and the cover members <NUM>, <NUM>.

Specifically, as shown in <FIG>, <FIG>, and <FIG>, the seal members 18a, 18b are respectively disposed between the bottom portions 38a, 39a of the cover arrangement portions <NUM>, <NUM> and facing surfaces 16a1, 17a1 of the cover members <NUM>, <NUM>. More specifically, the seal members 18a, 18b are respectively disposed between the bottom portions 38a, 39a of the cover arrangement portions <NUM>, <NUM> and seal grooves 16e, 17e of the cover members <NUM>, <NUM>.

The seal members 18a, 18b respectively abut on the cover members <NUM>, <NUM> and the cover arrangement portions <NUM>, <NUM>. Specifically, the seal members 18a, 18b are respectively disposed in the seal grooves 16e, 17e of the cover members <NUM>, <NUM>. In this state, when the cover members <NUM>, <NUM> are disposed on the cover arrangement portions <NUM>, <NUM> of the housing body <NUM>, the seal members 18a, 18b respectively abut on the bottom portions 38a, 39a of the cover arrangement portions <NUM>, <NUM>. The seal members 18a, 18b are preferably resin members such as resin O-rings.

Each of the pair of cover members <NUM>, <NUM> is a non-metal member. For example, each of the pair of cover members <NUM>, <NUM> is a resin member. As shown in <FIG>, the pair of cover members <NUM>, <NUM> respectively covers the pair of discharge portions <NUM>, <NUM>. The pair of cover members <NUM>, <NUM> are detachably attached to the housing <NUM>.

Specifically, the pair of cover members <NUM>, <NUM> are respectively disposed on the pair of cover arrangement portions <NUM>, <NUM>. As shown in <FIG>, the pair of cover members <NUM>, <NUM> are connected to each other by a bolt <NUM> and a nut <NUM> (an example of a connecting member).

For example, as shown in <FIG>, <FIG>, the cover members <NUM>, <NUM> include cover bodies 16a, 17a and at least one exhaust hollow 16b, 17b. The cover members <NUM>, <NUM> further include boss portions 16c, 17c, at least one first positioning protruded portion 16d, 17d (an example of a first protruded portion), and the seal grooves 16e, 17e (an example of a first recess portion). The cover members <NUM>, <NUM> further include holes 16f, 17f for tools.

The cover bodies 16a, 17a are respectively disposed on the cover arrangement portions <NUM>, <NUM> (see <FIG>). As shown in <FIG> and <FIG>, the cover bodies 16a, 17a respectively include the facing surfaces 16a1, 17a1 which faces the bottom portions 38a, 39a (see <FIG>) of the cover arrangement portions <NUM>, <NUM>.

As shown in <FIG> and <FIG>, rib portions <NUM>, <NUM> are respectively provided on the cover bodies 16a, 17a. For example, the pair of rib portions <NUM>, <NUM> are disposed so as to face each other and are integrally formed with the cover bodies 16a, 17a. Thereby, the rigidity of the cover bodies 16a, 17a can be improved.

As shown in <FIG>, <FIG>, at least one exhaust hollow 16b, 17b is provided on the cover bodies 16a, 17a. In this embodiment, an example in which at least one exhaust hollow 16b, 17b is a plurality of exhaust hollow, for example, three exhaust hollow is described. In <FIG>, <FIG>, the exhaust hollow 16b, 17b are indicated by hatching.

For example, the two exhaust hollow 16b, 17b are provided on the cover bodies 16a, 17a between the pair of rib portions <NUM>, <NUM>. The exhaust hollow 16b, 17b are provided on the cover bodies 16a, 17a on an outside of the rib portions <NUM>, <NUM>. In this embodiment, the exhaust hollow 16b, 17b are provided on the cover bodies 16a, 17a above the rib portions <NUM>, <NUM>.

The boss portions 16c, 17c shown in <FIG> and <FIG> are inserted into the pair of discharge portions <NUM>, <NUM> (see <FIG>) of the housing <NUM>. The bolt <NUM> or the nut <NUM> are disposed on the boss portions 16c, 17c. For example, the boss portions 16c, 17c include boss bodies 16ca, 17ca and slit portions 16cb, 17cb. The boss bodies 16ca, 17ca project respectively from the cover bodies 16a, 17a. The boss bodies 16ca, 17ca are formed in a columnar shape.

The Bolt <NUM> and/or the nut <NUM> (see <FIG>) are disposed in the slit portions 16cb, 17cb. As shown in <FIG> and <FIG>, the slit portion 16cb includes a small slit 16cb1 and a large slit 16cb2. The small slit 16cb1 is provided on the boss body 16ca. For example, the small slit 16cb1 is provided on the tip end side of the boss body 16ca. A shaft portion of the bolt <NUM> is disposed in the small slit 16cb1.

The large slit 16cb2 is provided on the boss body 17ca so as to be adjacent to the small slit 16cb1. For example, the large slit 16cb2 is provided on the base end side of the boss body 17ca. A slit width of the large slit 16cb2 is larger than a slit width of the small slit 16cb1. The head of the bolt <NUM> is disposed in the large slit 16cb2 (see <FIG>).

As shown in <FIG> and <FIG>, the slit portion 17cb includes a bolt hole 17cb1 and a slit 17cb2. The bolt hole 17cb1 is provided on the boss body 17ca. For example, the bolt hole 17cb1 is provided on the tip end side of the boss body 17ca. The shaft portion of the bolt <NUM> is inserted into the bolt hole 17cb1 (see <FIG>).

The slit 17cb2 is provided on the boss body 17ca so as to be adjacent to the bolt hole 17cb1. For example, the slit 17ccb2 is provided on the base end side of the boss body 17ca. A slit width of the slit 17cb2 is larger than a diameter of the bolt hole 17cb1. The nut <NUM> is disposed in the slit 17cb2. The slit width is defined in the direction perpendicular to a bolt axis center B1. For example, the slit width is defined in the front-rear direction along the facing surfaces 16a1, 17a1 of the cover bodies 16a, 17a.

As shown in <FIG>, <FIG>, <FIG>, and <FIG>, at least one first positioning protruded portion 16d, 17d is used for positioning the cover members <NUM>, <NUM> on the housing body <NUM>. At least one first positioning protruded portion 16d, 17d respectively protrudes from the cover body 16a, 17a. At least one first positioning protruded portion 16d, 17d is disposed along an inner peripheral surface of the pair of discharge portions <NUM>, <NUM> (see <FIG>).

In this embodiment, an example is described in which at least one first positioning protruded portion 16d, 17d is a plurality of first positioning protruded portions 16d, 17d, for example, the five first positioning protruded portions 16d, 17d.

As shown in <FIG>, <FIG>, <FIG>, and <FIG>, the seal members 18a, 18b (see <FIG>) are disposed in the seal grooves 16e, 17e. The seal grooves 16e, 17e are formed in a groove shape on the cover bodies 16a, 17a. The seal grooves 16e, 17e are formed in the groove shape so as to surround the boss portions 16c, 17c. The seal grooves 16e, 17e are formed in the groove shape on the facing surfaces 16a1, 17a1 of the cover bodies 16a, 17a, which faces the bottom portions 38a, 39a of the cover arrangement portions <NUM>, <NUM>, so as to surround the boss portions 16c, 17c.

As shown in <FIG>, <FIG>, <FIG>, and <FIG>, the holes 16f, 17f for the tool are used when the bolt <NUM> is screwed into the nut <NUM>. The holes 16f, 17f for the tool are provided on the cover bodies 16a, 17a and the boss portions 16c, 17c. The holes 16f, 17f for the tool are connected to the slit portions 16cb, 17cb of the boss portions 16c, 17c. For example, the holes 16f, 17f for the tool are respectively connected to the large slit 16cb2 and the slit 17cb2 of the boss portions 16c, 17c.

One of the cover members <NUM>, <NUM> further includes a second positioning protruded portion <NUM> (an example of a second protruded portion). In this embodiment, an example in which the cover member <NUM> further includes the second positioning protruded portion <NUM> is described. The second positioning protruded portion <NUM> projects from the cover body 16a. The second positioning protruded portion <NUM> is disposed in the positioning recess 38b (see <FIG>) of the cover arrangement portion <NUM> of the housing <NUM>.

The second positioning protruded portion <NUM> is provided on the cover body 16a in order to distinguish the cover member <NUM> from the cover member <NUM>. The positioning recess 38b is provided only on the cover arrangement portions <NUM>. In other words, the positioning recess 38b is not provided on the cover arrangement portion <NUM>.

It is possible to prevent erroneous assembly of the cover member <NUM> with respect to the cover arrangement portion <NUM> and erroneous assembly of the cover member <NUM> with respect to the cover arrangement portion <NUM>, by disposing the second positioning protruded portion <NUM> of the cover member <NUM> in the positioning recess 38b of the cover arrangement portion <NUM>.

The second positioning protruded portion <NUM> may be provided on the cover member <NUM>. In this case, the positioning recess 38b is provided on the cover arrangement portion <NUM>.

The pair of cover members <NUM>, <NUM> including the above configuration are attached to the housing <NUM> as follows. First, the seal members 18a, 18b are respectively disposed in the seal grooves 16e, 17e of the cover members <NUM>, <NUM>. Next, the bolt <NUM> is disposed in the boss portion 16c of the cover member <NUM> and the nut <NUM> is disposed on the boss portion 17c of the cover member <NUM>.

For example, the bolt <NUM> is disposed in the slit portion 16cb (the large slit 16cb2 and the small slit 16cb1) of the boss portion 16c, and the nut <NUM> is disposed in the slit portion 17cb (the slit 17cb2) of the boss portion 17c.

Subsequently, the boss portions 16c, 17c of the cover members <NUM>, <NUM> are respectively disposed inside the discharge portions <NUM>, <NUM> of the cover arrangement portions <NUM>, <NUM>. Thereby, the shaft portion of the bolt <NUM> is disposed as to be adjacent to the nut <NUM> in a state where the shaft portion of the bolt <NUM> is disposed in the slit portions 16cb, 17cb (the small slit 16cb1, the bolt hole 17cb1) of the boss portions 16c, 17c. In this state, the plurality of first positioning protruded portions 16d, 17d are disposed so as to respectively face the discharge portions <NUM>, <NUM>.

Subsequently, the tool is inserted into the hole 16f for the tool. The tool includes a hexagon wrench, a Phillips screwdriver, a flat head screwdriver, and the like. In this state, the bolt <NUM> is screwed into the nut <NUM> by rotating the tool.

The plurality of first positioning protruded portions 16d, 17d of the cover members <NUM>, <NUM> are respectively disposed inside the discharge portions <NUM>, <NUM> along the inner peripheral surfaces of the discharge portions <NUM>, <NUM> of the cover arrangement portions <NUM>, <NUM>. Further, the cover members <NUM>, <NUM> and the seal members 18a, 18b contact with the bottom portions 38a, 39a of the cover arrangement portions <NUM>, <NUM>. Thereby, the cover members <NUM>, <NUM> are respectively disposed on the cover arrangement portions <NUM>, <NUM> via the seal members 18a, 18b.

In a state where the cover members <NUM>, <NUM> and the seal member <NUM> are disposed on the cover arrangement portions <NUM>, <NUM>, a gap is provided between the tips of the pair of boss portions 16c, 17c. Thereby, the cover members <NUM>, <NUM> are connected to each other in a state where the cover members <NUM>, <NUM> and the seal members 18a, 18b press the bottom portions 38a, 39a of the cover arrangement portions <NUM>, <NUM>.

The configuration of the above embodiment may be configured as follows.

(A1) In the above embodiment, an example is described in which the seal members 18a, 18b are respectively disposed between the bottom portions 38a, 39a of the cover arrangement portions <NUM>, <NUM> and the facing surfaces 16a1, 17a1 of the cover bodies 16a, 17a. Instead of this, as shown in <FIG>, seal members 19a, 19b may be respectively disposed between an inner peripheral surfaces of the discharge portions <NUM>, <NUM> and the first positioning protruded portions 16d, 17d. Both of the seal members 18a, 18b of the above embodiment and the seal members 19a, 19b of this variation may be used.

(A2) In the above embodiment, as shown in <FIG> and <FIG>, an example is described in which the three exhaust hollow 16b, 17b are formed on the portions indicated by hatching. Instead of this, as shown in <FIG>, four exhaust hollow 16b, 17b may be formed on the cover members <NUM>, <NUM>.

(A3) In the above embodiment, an example is described in which the seal grooves 16e, 17e are provided on the cover members <NUM>, <NUM>. The seal grooves 16e, 17e may be provided on the housing <NUM>, for example, the bottom portions 38a, 39a of the cover arrangement portions <NUM>, <NUM>.

With the outboard motor <NUM> including the above-described configuration, the non-metal cover members <NUM>, <NUM> are attached to the housing <NUM> so as to cover the discharge portions <NUM>, <NUM>. In this state, the exhaust gas, which is discharged from the engine <NUM>, is discharged to the outside of the housing <NUM> through the exhaust hollow 16b, 17b of the non-metal cover members <NUM>, <NUM>.

In this configuration, the exhaust gas, which is discharged from the exhaust hollow 16b, 17b of the cover members <NUM>, <NUM>, adheres to the outer surface around the exhaust hollow 16b, 17b. In this case, discoloration around the exhaust hollow 16b, 17b of the cover members <NUM>, <NUM> can be suppressed, because the cover members <NUM>, <NUM> are made of non-metal.

With the outboard motor <NUM>, the discoloration around the exhaust hollow 16b, 17b of the cover members <NUM>, <NUM> can be suppressed, because the cover members <NUM>, <NUM> are made of resin.

With the outboard motor <NUM>, the discoloration around the exhaust hollow 16b, 17b of the cover members <NUM>, <NUM> can be suppressed in a state where the discharge portions <NUM>, <NUM> are provided between the engine <NUM> and the cavitation plate <NUM>.

With the outboard motor <NUM>, the discoloration around the exhaust hollow 16b, 17b of the cover members <NUM>, <NUM> can be suppressed in a state where the discharge portions <NUM>, <NUM> are disposed on the cover arrangement portions <NUM>, <NUM> of the housing <NUM>.

With the outboard motor <NUM>, the cover members <NUM>, <NUM> are suitably positioned on the housing <NUM> by disposing the first positioning protruded portions 16d, 17d of the cover members <NUM>, <NUM> on the discharge portions <NUM>, <NUM> of the cover arrangement portions <NUM>, <NUM>.

With the outboard motor <NUM>, the exhaust gas can be suitably discharged from the exhaust hollow 16b, 17b of the cover members <NUM>, <NUM>, because the seal members 18a, 18b, 19a, 19b are disposed between the housing <NUM> and the cover members <NUM>, <NUM>.

With the outboard motor <NUM>, the seal member <NUM> can be suitably abut on the housing <NUM> and the cover members <NUM>, <NUM>, because the seal members 18a, 18b are disposed in the seal grooves 16e, 17e.

With the outboard motor <NUM>, the cover members <NUM>, <NUM> can be easily and surely attached to the housing <NUM>, because the pair of cover members <NUM>, <NUM> are connected to each other by the bolt <NUM> and the nut <NUM>.

With the outboard motor <NUM>, the second positioning protruded portion <NUM> is formed only on the cover member <NUM> and is disposed in the positioning recess 38b provided on one side surface of the housing <NUM>. Thereby, it is possible to prevent erroneous assembly of the pair of cover members <NUM>, <NUM>.

With the outboard motor <NUM>, the cooling water and the exhaust gas can be suitably discharged from the discharge chamber R to the outside of the housing <NUM> through the exhaust hollow 16b, 17b of the cover members <NUM>, <NUM> and the discharge portions <NUM>, <NUM>, because the exhaust passage P1 and the cooling water passage P2 are connected to the discharge chamber R.

(B1) In the above embodiment, an example is described in which the exhaust passage P1 and the cooling water passage P2 are connected to the discharge chamber R. Instead of this, one of the exhaust passage P1 and the cooling water passage P2 may be connected to the other of the exhaust passage P1 and the cooling water passage P2, and the other of the exhaust passage P1 and the cooling water passage P2 may be connected to the discharge chamber R.

In this case, the wall portions 37a for the exhaust gas of <FIG> is connected to the wall portions 37b for the cooling water passage P2 which is provided between the engine <NUM> and the discharge chamber R. The same effect as the above effect can be obtained with this configuration.

(B2) In the above embodiment, an example is described in which the cover members <NUM>, <NUM> include three or four exhaust hollow 16b, 17b. The number of the exhaust hollow 16b, 17b of the cover members <NUM>, <NUM> may be set to any number, as long as the number of the exhaust hollow 16b, 17b is more than one.

Claim 1:
An outboard motor (<NUM>) comprising:
an engine (<NUM>);
a drive shaft (<NUM>) extending in a first direction from the engine (<NUM>);
a propeller shaft (<NUM>) extending in a direction intersecting with the drive shaft (<NUM>);
a housing (<NUM>) configured to accommodate the engine (<NUM>), the drive shaft (<NUM>), and the propeller shaft (<NUM>) and includes a pair of discharge portions (<NUM>, <NUM>), the discharge portions (<NUM>, <NUM>) discharging exhaust gas and cooling water of the engine (<NUM>);
a discharge passage (P) configured to guide the exhaust gas and the cooling water from the engine (<NUM>) to the discharge portion (<NUM>, <NUM>) inside the housing (<NUM>); and
a pair of non-metal cover members (<NUM>, <NUM>) detachably attached to the housing (<NUM>) so as to cover the pair of discharge portions (<NUM>, <NUM>) respectively and are connected to each other by a connecting member (<NUM>, <NUM>), the cover members (<NUM>, <NUM>) include an exhaust hollow (16b, 17b) respectively.