Patent Description:
In an exhaust system of a straddle-type vehicle, a chamber for muffling is provided at a downstream side of an exhaust pipe extending from an engine. When the exhaust gas flows into the chamber from the exhaust pipe, the exhaust gas expands in the chamber and the energy of the exhaust noise is attenuated. In the exhaust system of the straddle-type vehicle, although the exhaust gas is purified by a catalyst, a sufficient purification performance of the exhaust gas cannot be obtained until the catalyst reaches the activation temperature. Therefore, there is known a structure in which a catalyst is installed in a chamber to be warmed up to an activation temperature at an early stage using heat of high-temperature exhaust gas in the chamber (for example, see Patent Literature <NUM>).

Patent Literature <NUM>: <CIT>; <CIT> relates to exhaust system for a motorcycle; <CIT> relates to an exhaust structure of a vehicle; <CIT> relates to a catalyst arrangement structure for a motorcycle.

With stricter regulations on the exhaust gas in recent years, there is a demand for further improvement of the exhaust gas purification performance. In the exhaust device described in Patent Literature <NUM>, however, since the catalyst is installed in the chamber, a distance from an exhaust port of an engine to the catalyst is long and the activation of the catalyst may be delayed.

The present invention is made in view of the above circumstance, and an object of the present invention is to provide an exhaust device that can implement early activation of a catalyst.

To solve the above problem, an exhaust device according to an aspect of the present invention purifies exhaust gas discharged from an engine through an exhaust pipe. The exhaust device includes: a chamber that forms an expansion chamber of the exhaust gas at a downstream side of the exhaust pipe; a partition wall that partitions the expansion chamber into a first expansion chamber and a second expansion chamber; an introduction pipe that enters the second expansion chamber from a downstream end of the exhaust pipe; and a catalyst interposed at an intermediate portion of the introduction pipe in the second expansion chamber. The partition wall is formed with a first opening connecting an outlet of the introduction pipe to the first expansion chamber and a second opening connecting the first expansion chamber to the second expansion chamber. The second opening overlaps with the catalyst when viewed from a side of the first expansion chamber such that the exhaust gas is blown from the second opening to a side surface of the catalyst to warm up the catalyst. In a plan view, a center line of the catalyst is parallel to the partition wall.

According to the exhaust device of the aspect of the present invention, the exhaust gas flows from the exhaust pipe to the introduction pipe in the chamber, passes through the catalyst, and flows into the first expansion chamber from the first opening. The exhaust gas in the first expansion chamber flows from the first opening toward the second opening, and is intensively blown to an outer surface of the catalyst in the second expansion chamber from the second opening. The catalyst is warmed up in a short time by the heat of the high-temperature exhaust gas, and the purification performance of the exhaust gas can be improved by early activation of the catalyst.

An exhaust device according to an aspect of the present invention purifies the exhaust gas discharged from an engine through an exhaust pipe. A chamber forming an expansion chamber of the exhaust gas is provided at a downstream side of the exhaust pipe. The expansion chamber of the chamber is partitioned into a first expansion chamber and a second expansion chamber by a partition wall. An introduction pipe enters the second expansion chamber from a downstream end of the exhaust pipe, and a catalyst is interposed in the second expansion chamber at an intermediate portion of the introduction pipe. An outlet of the introduction pipe is connected to the first expansion chamber through a first opening of the partition wall, the exhaust gas flows from the exhaust pipe to the introduction pipe in the chamber, passes through the catalyst, and flows into the first expansion chamber through the first opening. The first expansion chamber is connected to the second expansion chamber through a second opening of the partition wall, and the exhaust gas in the first expansion chamber flows into the second expansion chamber through the second opening. At this time, the second opening overlaps with the catalyst when viewed from the first expansion chamber side, and the exhaust gas is intensively blown from the second opening to an outer surface of the catalyst in the second expansion chamber. The catalyst is warmed up in a short time by the heat of the high-temperature exhaust gas, and the purification performance of the exhaust gas can be improved by early activation of the catalyst.

Hereinafter, a present embodiment will be described in detail with reference to the accompanying drawings. <FIG> is a left view of a periphery of an engine according to the present embodiment. <FIG> is a right view of the periphery of the engine according to the present embodiment. In the following drawings, an arrow FR indicates a vehicle front side, an arrow RE indicates a vehicle rear side, an arrow L indicates a vehicle left side, and an arrow R indicates a vehicle right side. Upstream side and downstream side indicate upstream side and downstream side in the flow direction of the exhaust gas.

As shown in <FIG> and <FIG>, an engine <NUM> is a parallel two-cylinder engine. A cylinder block <NUM> is disposed at an upper portion of a crankcase <NUM>. A cylinder head <NUM> is attached to an upper portion of the cylinder block <NUM>. Ahead cover (not shown) is attached to an upper portion of the cylinder head <NUM>. An oil pan <NUM> that stores oil for lubrication and cooling is attached to a lower portion of the crankcase <NUM>. A magneto cover <NUM> that covers a magneto chamber in the crankcase is attached to a left side surface of the crankcase <NUM>. A clutch cover <NUM> that covers a clutch chamber in the crankcase is attached to a right side surface of the crankcase <NUM>.

The engine <NUM> is supported by a pair of left and right main frames <NUM> of a straddle-type vehicle. Swing arms <NUM> that support a rear wheel (not shown) are swingably supported by the pair of main frames <NUM>. The swing arms <NUM> are coupled to a rear suspension <NUM> for absorbing shock to the rear wheel. An upper end of the rear suspension <NUM> is coupled to the main frames <NUM>. A lower end of the rear suspension <NUM> is coupled to the swing arms <NUM> via a link arm <NUM> and a link bracket <NUM>. A chamber <NUM> of an exhaust device <NUM> is supported at lower portions of the pair of main frames <NUM> via left and right brackets 49a and 49b.

The exhaust gas flows into the chamber <NUM> through a pair of exhaust pipes 31a and 31b and is discharged from the chamber <NUM> to the outside through a muffler <NUM>. At this time, although the exhaust gas is purified by a catalyst in the exhaust path, a sufficient purification performance cannot be obtained until the catalyst reaches the activation temperature. Therefore, in the exhaust device <NUM> according to the present embodiment, a pipe extending from rear ends of the pair of exhaust pipes 31a and 31b enters the chamber <NUM>, and the catalyst is installed at an intermediate portion of the pipe in the chamber <NUM>. The exhaust gas that has passed through the catalyst forms a flow in the chamber <NUM> toward the outer surface of the catalyst, and the catalyst in the chamber <NUM> is activated at an early stage by the heat of the exhaust gas.

Hereinafter, a detailed configuration of the exhaust device will be described with reference to <FIG> and <FIG>. <FIG> is a perspective view of an exhaust device according to the present embodiment. <FIG> is a top view of a chamber according to the present embodiment. <FIG> is a side view of the chamber according to the present embodiment. <FIG> is a perspective view of the chamber according to the present embodiment when an upper half body is removed. <FIG> is a top view of the chamber according to the present embodiment when the upper half body is removed. <FIG> is a cross-sectional view of the chamber of <FIG> taken along a line A-A.

As shown in <FIG>, the exhaust device <NUM> reduces the exhaust noise of the exhaust gas discharged from the engine <NUM> (see <FIG>) through the exhaust pipes 31a and 31b and purifies the exhaust gas. The exhaust pipes 31a and 31b extend downward from a front surface of the engine <NUM> and are integrated into one by an introduction pipe <NUM>. The integrated one exhaust pipe is connected to the chamber <NUM>. An upstream side of the introduction pipe <NUM> is exposed to the outside of the chamber <NUM>. A first catalyst <NUM> is interposed on the upstream side of the introduction pipe <NUM>. A downstream side of the introduction pipe <NUM> enters the chamber <NUM>. A second catalyst <NUM> (see <FIG>) is interposed on the downstream side of the introduction pipe <NUM>.

When the exhaust gas flows from the exhaust pipes 31a and 31b into the introduction pipe <NUM>, air pollutants such as carbon monoxide (CO), hydrocarbons (HC), and nitrogen oxides (NOx) contained in the exhaust gas are purified by the first and second catalysts <NUM> and <NUM>. When the exhaust gas flows from the introduction pipe <NUM> into the chamber <NUM>, the exhaust gas is expanded by an expansion chamber <NUM> (see <FIG>) in the chamber <NUM> and the exhaust noise is reduced. The muffler <NUM> is connected to a downstream side of the chamber <NUM> via a lead-out pipe <NUM>, and the exhaust gas that has passed through the chamber <NUM> is discharged to the outside from the muffler <NUM>. Since the exhaust noise is reduced by the chamber <NUM>, an expansion chamber of the muffler <NUM> is reduced in size and the muffler <NUM> is reduced in size.

As shown in <FIG>, <FIG>, and <FIG>, the chamber <NUM> has a substantially rectangular box shape in a top view and includes an upper half body <NUM> and a lower half body <NUM>. The expansion chamber <NUM> of the exhaust gas (see <FIG>) is formed at a downstream side of the exhaust pipes 31a and 31b. As described above, the chamber <NUM> is attached to the lower portions of the main frames <NUM> and is located below the engine <NUM> and rearward of the oil pan <NUM>. The overall height of the chamber <NUM> is reduced so that the chamber <NUM> would not interfere with the link arm <NUM> or the like of the rear suspension <NUM>. Although the height of the chamber <NUM> decreases from a front side toward a rear side, an attachment portion <NUM> for the lead-out pipe <NUM> on a rear right side of the chamber <NUM> bulges upward.

A concave surface <NUM> for avoiding a center stand (not shown) is provided on a left side surface of the chamber <NUM>. The bracket 49a for attaching the chamber <NUM> is installed on the concave surface <NUM>. Aright side surface of the chamber <NUM> is substantially flat, the bracket 49b for attaching the chamber <NUM> is installed on a front side of the right side surface, and the exhaust gas lead-out pipe <NUM> is connected to a rear side of the right side surface. A concave surface <NUM> for avoiding the rear wheel (not shown) is provided on a rear surface of the chamber <NUM>. A bulging portion <NUM>, which will be described later, is formed on a left side of a front surface of the chamber <NUM>. The exhaust gas introduction pipe <NUM> is inserted into a right side of the front surface of the chamber <NUM>.

As shown in <FIG>, the expansion chamber <NUM> of the chamber <NUM> is partitioned into a first expansion chamber <NUM> and a second expansion chamber <NUM> adjacent in the vehicle width direction by a partition wall <NUM> extending in the vehicle front-rear direction. In the present embodiment, the first expansion chamber <NUM> is formed on a vehicle left side of the chamber <NUM>, and the second expansion chamber <NUM> is formed on a vehicle right side of the chamber <NUM>. No member is installed in the first expansion chamber <NUM>, and the introduction pipe <NUM> enters the second expansion chamber <NUM> from a right opening <NUM> of a front wall <NUM> of the chamber <NUM>. The introduction pipe <NUM> enters from a front side to the center of the second expansion chamber <NUM>, and no member is installed on a rear side of the second expansion chamber <NUM>.

The introduction pipe <NUM> includes an upstream pipe <NUM> disposed upstream of the first catalyst <NUM>, a midstream pipe <NUM> between the first and second catalysts <NUM> and <NUM>, and a downstream pipe <NUM> disposed downstream of the second catalyst <NUM>. The upstream pipe <NUM> connects the exhaust pipes 31a and 31b and the first catalyst <NUM>, outside the chamber <NUM>. The midstream pipe <NUM> is inserted into the right opening <NUM> of the front wall <NUM> of the chamber <NUM>, and connects the first catalyst <NUM> outside the chamber <NUM> and the second catalyst <NUM> inside the chamber <NUM>. The downstream pipe <NUM> is curved in a substantially arc shape in a plan view in the second expansion chamber <NUM> and connects the second catalyst <NUM> and the partition wall <NUM>. In this way, the second catalyst <NUM> interposed at an intermediate portion of the introduction pipe <NUM> is installed in the second expansion chamber <NUM>.

The partition wall <NUM> is formed with a first opening <NUM> connecting an outlet of the introduction pipe <NUM> (downstream pipe <NUM>) to the first expansion chamber <NUM>, and the exhaust gas is introduced from the introduction pipe <NUM> into the first expansion chamber <NUM> through the first opening <NUM>. The first opening <NUM> is formed in an elliptical shape having an inclined major axis, and the downstream pipe <NUM> is connected to an opening edge of the first opening <NUM>. An upstream end of the downstream pipe <NUM> is formed in a perfect circular shape fitting with the cylindrical second catalyst <NUM>. A downstream end of the downstream pipe <NUM> is formed in an elliptical shape fitting with the first opening <NUM>. The height of the downstream pipe <NUM> decreases from the upstream end toward the downstream end, and thus the height of the chamber <NUM> is reduced.

The partition wall <NUM> is further formed with a second opening <NUM> forward of the first opening <NUM>. The second opening <NUM> connects the first expansion chamber <NUM> to the second expansion chamber <NUM>. The exhaust gas flows from the first expansion chamber <NUM> into the second expansion chamber <NUM> through the second opening <NUM>. The second opening <NUM> is formed in a rectangular shape elongated in the front-rear direction, and overlaps with the second catalyst <NUM> when viewed from the first expansion chamber <NUM> side. In a plan view, the center line of the second catalyst <NUM> is parallel to the partition wall <NUM>, and an outer circumferential surface of the second catalyst <NUM> is exposed to the first expansion chamber <NUM> from the second opening <NUM>. The exhaust gas in the first expansion chamber <NUM> is blown to the outer circumferential surface of the second catalyst <NUM> through the second opening <NUM>, and the second catalyst <NUM> is activated at an early stage.

The partition wall <NUM> is further formed with a third opening <NUM> rearward of the first opening <NUM>. The third opening <NUM> connects the first expansion chamber <NUM> to the second expansion chamber <NUM>. The exhaust gas flows from the first expansion chamber <NUM> into the second expansion chamber <NUM> through the third opening <NUM>. The third opening <NUM> is formed in a rectangular shape elongated in the height direction, and overlaps with a part of the inlet <NUM> of the lead-out pipe <NUM> when viewed from the first expansion chamber <NUM> side. The exhaust gas in the first expansion chamber <NUM> easily flows directly into the inlet <NUM> of the lead-out pipe <NUM> through the third opening <NUM>. In this way, the first and second expansion chambers <NUM> and <NUM> are connected in two front and rear positions through the first and third openings <NUM> and <NUM>.

The second opening <NUM> has a largest area, followed by the first opening <NUM> and then the third opening <NUM>. Since the area of the second opening <NUM> is larger than the area of the first opening <NUM>, the exhaust gas smoothly flows from the first opening <NUM> toward the outer surface of the second catalyst <NUM> through the second opening <NUM>. Since the area of the third opening <NUM> is smaller than the area of the second opening <NUM>, the flow of the exhaust gas from the first opening <NUM> toward the second opening <NUM> would not be excessively hindered by the third opening <NUM>. The area of the second opening <NUM> is larger than a vertical projection area of the second catalyst <NUM> when the second catalyst <NUM> is viewed from the first expansion chamber <NUM>, and the exhaust gas is effectively blown to the second catalyst <NUM> from the second opening <NUM>.

The front wall <NUM> of the chamber <NUM> is formed with the bulging portion <NUM> that expands the first expansion chamber <NUM> forward from the first opening <NUM> toward the second opening <NUM>. The bulging portion <NUM> bulges to a position overlapping with the first catalyst <NUM> in a side view. The expansion of the first expansion chamber <NUM> facilitates the flow of the exhaust gas from the first opening <NUM> to the second opening <NUM>. A left side wall <NUM> of the chamber <NUM> is formed with an inclined surface <NUM> that guides the exhaust gas entering the first expansion chamber <NUM> from the first opening <NUM> to the second opening <NUM>. Since the exhaust gas flows along the inclined surface <NUM>, the exhaust gas easily flows from the first expansion chamber <NUM> into the second opening <NUM>.

The lead-out pipe <NUM> is connected to a right side wall <NUM> of the chamber <NUM>. The exhaust gas is discharged to the outside from the second expansion chamber <NUM> by the lead-out pipe <NUM>. The inlet <NUM> of the lead-out pipe <NUM> is located rearward (downstream) of the installation location of the second catalyst <NUM> in the second expansion chamber <NUM>. For this reason, the flow of the exhaust gas from the second opening <NUM> toward the inlet <NUM> of the lead-out pipe <NUM> through the installation location of the second catalyst <NUM> is formed in the chamber <NUM>. When the exhaust gas passes through the installation location of the second catalyst <NUM>, the second catalyst <NUM> is effectively warmed up by the heat of the exhaust gas. In the present embodiment, the muffler <NUM> (see <FIG>) is connected at a downstream side of the lead-out pipe <NUM>. Alternatively, the lead-out pipe <NUM> may function as a tail pipe in an engine without the muffler <NUM>.

The flow of the exhaust gas in the chamber will be described with reference to <FIG> is a view which shows a flow of the exhaust gas in the chamber according to the present embodiment.

As shown in <FIG>, the exhaust gas is sent from the exhaust pipes 31a and 31b (see <FIG>) to the chamber <NUM> through the introduction pipe <NUM>, and flows from the introduction pipe <NUM> into the first expansion chamber <NUM> through the first opening <NUM>. As described above, since the first expansion chamber <NUM> is expanded forward by the bulging portion <NUM>, the volume of the first expansion chamber <NUM> forward of the first opening <NUM> is larger than that rearward of the first opening <NUM>. The area of the second opening <NUM> is larger than the area of the third opening <NUM>. For this reason, the exhaust gas in the first expansion chamber <NUM> easily flows forward from the first opening <NUM>, and the flow rate of the exhaust gas flowing from the first opening <NUM> toward the second opening <NUM> is large.

The inclined surface <NUM> of the left side wall <NUM> of the chamber <NUM> is inclined such that an interval between the inclined surface <NUM> and the partition wall <NUM> decreases toward the front. The exhaust gas in the first expansion chamber <NUM> is guided to the second opening <NUM> by the inclined surface <NUM>, and flows into the second expansion chamber <NUM> from the second opening <NUM>. Since the second opening <NUM> overlaps with the second catalyst <NUM> in a side view (see <FIG>), the high-temperature exhaust gas is blown from the second opening <NUM> to a side surface of the second catalyst <NUM> to warm up the second catalyst <NUM>. As indicated by an arrow D1, the flow of the exhaust gas from the first opening <NUM> toward the lead-out pipe <NUM> through the second catalyst <NUM> is formed inside the chamber <NUM>.

A part of the exhaust gas in the first expansion chamber <NUM> flows rearward from the first opening <NUM>, and flows into the second expansion chamber <NUM> from the third opening <NUM>. The third opening <NUM> faces the inlet <NUM> of the lead-out pipe <NUM>, and the exhaust gas flows from the third opening <NUM> toward the lead-out pipe <NUM>. As indicated by an arrow D2, the flow of the exhaust gas from the first opening <NUM> toward the lead-out pipe <NUM> at a shortest distance is formed inside the chamber <NUM>. When the exhaust gas flows as indicated by the arrows D1 and D2 and flows from the second expansion chamber <NUM> into the lead-out pipe <NUM>, the exhaust gas in the lead-out pipe <NUM> is discharged to the outside through the muffler <NUM> (see <FIG>).

According to the present embodiment described above, the exhaust gas flows from the exhaust pipes 31a and 31b to the introduction pipe <NUM> in the chamber <NUM>, and passes through the inside of the second catalyst <NUM> and flows into the first expansion chamber <NUM> from the first opening <NUM>. The exhaust gas in the first expansion chamber <NUM> flows from the first opening <NUM> toward the second opening <NUM>, and is intensively blown to the outer surface of the second catalyst <NUM> in the second expansion chamber <NUM> from the second opening <NUM>. The second catalyst <NUM> is warmed up in a short time by the heat of the high-temperature exhaust gas, and the purification performance of the exhaust gas can be improved by the early activation of the second catalyst <NUM>.

In the present embodiment, the expansion chamber of the chamber is partitioned into the first and second expansion chambers adjacent in the vehicle width direction (left-right direction) by the partition wall. However, the method for partitioning the expansion chamber by the partition wall is not particularly limited. For example, the expansion chamber of the chamber may be partitioned by a partition wall into first and second expansion chambers adjacent in the front-rear direction.

In the present embodiment, the first expansion chamber is formed on a left side of the chamber and the second expansion chamber is formed on a right side of the chamber. Alternatively, the second expansion chamber may be formed on the left side of the chamber and the first expansion chamber may be formed on the right side of the chamber. In this case, the introduction pipe enters the left side of the chamber, and the catalyst is installed in the second expansion chamber on the left side of the chamber.

In the present embodiment, the first catalyst is interposed in the introduction pipe outside the chamber and the second catalyst is interposed in the introduction pipe inside the chamber. Alternatively, at least one catalyst may be interposed in the introduction pipe inside the chamber. For example, catalyst may be interposed only in the introduction pipe in the chamber, or a plurality of catalysts may be interposed in the introduction pipe in the chamber.

In the present embodiment, the introduction pipe enters the second expansion chamber from the front wall of the chamber. However, the introduction pipe may be formed as long as the introduction pipe enters the second expansion chamber. For example, the introduction pipe may enter the second expansion chamber from the right side wall, an upper wall, or a bottom wall of the chamber.

In the present embodiment, the bulging portion is formed in the chamber. Alternatively, the bulging portion may not be formed in the chamber as long as a sufficient volume of the first expansion chamber can be ensured.

In addition, the exhaust device according to the present embodiment can be appropriately applied to other straddle-type vehicles such as a buggy-type automatic three-wheel vehicle. Here, the straddle-type vehicle is not limited to a general vehicle on which a rider rides at a posture of straddling a seat, and further includes a scooter-type vehicle on which a rider rides without straddling a seat.

As described above, an exhaust device (<NUM>) according to the present embodiment purifies exhaust gas discharged from an engine (<NUM>) through an exhaust pipe (31a, 31b). The exhaust device includes: a chamber (<NUM>) that forms an exhaust chamber (<NUM>) of the exhaust gas at a downstream side of the exhaust pipe; a partition wall (<NUM>) that partitions the expansion chamber into a first expansion chamber (<NUM>) and a second expansion chamber (<NUM>); an introduction pipe (<NUM>) that enters the second expansion chamber from a downstream end of the exhaust pipe; and a catalyst (second catalyst <NUM>) interposed at an intermediate portion of the introduction pipe in the second expansion chamber. The partition wall is formed with a first opening (<NUM>) connecting an outlet of the introduction pipe to the first expansion chamber and a second opening (<NUM>) connecting the first expansion chamber to the second expansion chamber. The second opening overlaps with the catalyst when viewed from a side of the first expansion chamber. According to this configuration, the exhaust gas flows from the exhaust pipe to the introduction pipe in the chamber, passes through the catalyst, and flows into the first expansion chamber from the first opening. The exhaust gas in the first expansion chamber flows from the first opening toward the second opening, and is intensively blown to an outer surface of the catalyst in the second expansion chamber from the second opening. The catalyst is warmed up in a short time by the heat of the high-temperature exhaust gas, and the purification performance of the exhaust gas can be improved by early activation of the catalyst.

In the exhaust device according to the present embodiment, the partition wall partitions the expansion chamber into the first expansion chamber and the second expansion chamber adjacent in the vehicle width direction. The second opening is located forward of the first opening, and an area of the second opening is larger than an area of the first opening. According to this configuration, the partition wall extends in a front-rear direction to partition the first expansion chamber and the second expansion chamber, and thus the second opening can be formed longer in the front-rear direction in the partition wall and the overlap between the second opening and the catalyst can be made large. Since the area of the second opening is larger than the area of the first opening, the exhaust gas can smoothly flow from the first opening toward the outer surface of the catalyst through the second opening.

In the exhaust device according to the present embodiment, the partition wall is further formed with a third opening (<NUM>) on a side opposite to the second opening with the first opening therebetween. The third opening connects the first expansion chamber and the second expansion chamber. An area of the third opening is smaller than the area of the second opening. According to this configuration, even when the third opening is formed in the partition wall, the flow of the exhaust gas from the first opening toward the second opening would not be excessively hindered.

The exhaust device according to the present embodiment further includes a lead-out pipe (<NUM>) that is configured to discharge the exhaust gas from the second expansion chamber to the outside, and an inlet (<NUM>) of the lead-out pipe is located at a downstream side of an installation position of the catalyst in the second expansion chamber. According to this configuration, the flow of the exhaust gas from the second opening toward the inlet of the lead-out pipe through the installation location of the catalyst is formed in the chamber, and the catalyst is effectively warmed up by the heat of the exhaust gas when the exhaust gas passes through the installation location of the catalyst.

In the exhaust device according to the present embodiment, an outer wall of the chamber is formed with a bulging portion (<NUM>) that is configured to expand the first expansion chamber in a direction from the first opening toward the second opening. According to this configuration, the exhaust gas can easily flow from the first opening toward the second opening by the expansion of the first expansion chamber.

Claim 1:
An exhaust device (<NUM>) that purifies exhaust gas discharged from an engine (<NUM>) through an exhaust pipe (31a, 31b), the exhaust device (<NUM>) comprising:
a chamber (<NUM>) that forms an expansion chamber (<NUM>) of the exhaust gas at a downstream side of the exhaust pipe (31a, 31b);
a partition wall (<NUM>) that partitions the expansion chamber (<NUM>) into a first expansion chamber (<NUM>) and a second expansion chamber (<NUM>);
an introduction pipe (<NUM>) that enters the second expansion chamber (<NUM>) from a downstream end of the exhaust pipe (31a, <NUM> lb); and
a catalyst (<NUM>) interposed at an intermediate portion of the introduction pipe (<NUM>) in the second expansion chamber (<NUM>),
characterized in that
the partition wall (<NUM>) is formed with a first opening (<NUM>) connecting an outlet of the introduction pipe (<NUM>) to the first expansion chamber (<NUM>) and a second opening (<NUM>) connecting the first expansion chamber (<NUM>) to the second expansion chamber (<NUM>), and the second opening (<NUM>) overlaps with the catalyst (<NUM>) when viewed from a side of the first expansion chamber (<NUM>) such that the exhaust gas is blown from the second opening (<NUM>) to a side surface of the catalyst (<NUM>) to warm up the catalyst (<NUM>), and
in a plan view, a center line of the catalyst (<NUM>) is parallel to the partition wall (<NUM>).