Exhaust

Abstract

The present invention provides an exhaust device that ensures a silencer chamber below an engine and realizes a miniaturized silencer. The exhaust device (50) guides exhaust gas from an exhaust pipe (51L) in front of an engine (30) to a silencer at the rear of the engine. The exhaust device is provided with a catalytic shell (61) containing a catalyst (62) for purifying exhaust gas passing through the exhaust pipe, and a chamber (71) formed downstream of the catalytic shell with a silencer chamber for reducing exhaust noise. The catalytic shell is arranged in a range from the front space of the engine to the front side of the lower space, and the chamber is arranged to occupy at least the rear side of the lower space of the engine.

Description

Technical Field

[0001] The invention relates to an exhaust device. Background Art

[0002] In the past, as an exhaust device for a riding vehicle, there is a known device in which a catalytic housing is arranged below the engine (for example, refer to Patent Document 1). In the exhaust device described in Patent Document 1, four exhaust pipes extend downward from the front surface of the engine, and the four exhaust pipes converge into a single collecting pipe below the engine and are connected to the catalytic housing. An exhaust pipe is connected to the downstream of the catalytic housing, and the exhaust pipe extends to the side of the rear wheel and is connected to the muffler. When the exhaust gas enters the muffler from the catalytic housing, the exhaust sound is reduced by the expansion of the exhaust gas in the muffler chamber in the muffler.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2012-052514

[0006] Problems to be solved by the invention

[0007] In the exhaust device described in Patent Document 1, the lower part of the engine is occupied by the manifold and the catalyst housing, and it is difficult to ensure a muffler chamber of sufficient volume upstream of the muffler. Therefore, the volume of the muffler chamber in the muffler increases, resulting in an increase in the size of the muffler. Summary of the invention

[0008] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide an exhaust device capable of ensuring a muffler chamber below an engine and achieving miniaturization of a muffler.

[0009] Technical solutions to solve problems

[0010] An exhaust device according to one embodiment of the present invention is an exhaust device that guides exhaust gas from an exhaust pipe in front of an engine to a muffler in the rear of the engine, and comprises: a catalytic shell that accommodates a catalyst for purifying exhaust gas that has passed through the exhaust pipe; and a chamber that forms a silencer chamber for reducing exhaust sound downstream of the catalytic shell, the catalytic shell being arranged in a range from the front space of the engine to the front side of the lower space of the engine, and the chamber being arranged to occupy at least the rear side of the lower space of the engine, thereby solving the above-mentioned problem.

[0011] Effects of the Invention

[0012] According to an exhaust device of one embodiment of the present invention, the catalytic housing is arranged in the front space of the engine or the front side of the lower space, and the lower space of the engine is not occupied by the catalytic housing. A chamber is arranged in a large range of the lower space of the engine, and the exhaust sound is reduced by using the silencer chamber of the chamber. By ensuring the silencer chamber on the upstream side of the muffler, the muffler can be miniaturized. Therefore, while maintaining the silencing performance, the risk of thermal damage to the surface of the muffler is reduced by miniaturizing the muffler, and the degree of freedom of design of the appearance of the muffler can be increased. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a right side view of the riding type vehicle of this embodiment.

[0014] Figure 2 It is a front view of the engine of this embodiment.

[0015] Figure 3 It is a side view of the engine of this embodiment.

[0016] Figure 4 It is a bottom view of the engine of this embodiment.

[0017] Figure 5 Yes Figure 4 Section view along line AA.

[0018] Figure 6 Yes Figure 4 Sectional view along line BB.

[0019] Figure 7 It is a bottom view of the engine of the modified example.

[0020] Explanation of symbols

[0021] 30: Engine

[0022] 35: Crankshaft

[0023] 37: Oil pan

[0024] 41: Deep bottom of the oil pan

[0025] 42: Bottom of the oil pan

[0026] 43: Sloped part of the oil pan

[0027] 50: Exhaust

[0028] 51L, 51R: Exhaust pipe

[0029] 61: Secondary catalytic shell (catalytic shell)

[0030] 62: Secondary catalyst (catalyst)

[0031] 63: Upper surface of secondary catalytic shell

[0032] 64: Side of secondary catalytic shell

[0033] 71: Chamber

[0034] 72: Anechoic Chamber

[0035] 76: Upper surface of the chamber

[0036] 77: Side of the chamber

[0037] 81: Exhaust pipe

[0038] 82: Muffler DETAILED DESCRIPTION

[0039] An exhaust device according to one embodiment of the present invention guides exhaust gas from an exhaust pipe in front of an engine to a muffler in the rear of the engine. A catalytic housing is provided downstream of the exhaust pipe, and a catalyst for purifying exhaust gas passing through the exhaust pipe is accommodated in the catalytic housing. A chamber is provided downstream of the catalytic housing, and a muffler chamber for reducing exhaust noise is formed in the chamber. The catalytic housing is arranged in a range from the front space of the engine to the front side of the lower space, and the chamber is arranged to occupy at least the rear side of the lower space of the engine. The lower space of the engine is not occupied by the catalytic housing, and a chamber is arranged in a large range of the lower space of the engine, and the exhaust noise is reduced by the muffler chamber of the chamber. By ensuring the muffler chamber on the upstream side of the muffler, the muffler can be miniaturized. Therefore, while maintaining the muffler performance, the risk of thermal damage to the surface of the muffler is reduced by miniaturizing the muffler, and the degree of freedom in the design of the appearance of the muffler can be increased.

[0040] Example

[0041] Hereinafter, this embodiment will be described in detail with reference to the accompanying drawings. Figure 1 It is a right side view of the riding type vehicle of this embodiment. In the following figures, arrow FR indicates the front of the vehicle, arrow RE indicates the rear of the vehicle, arrow L indicates the left side of the vehicle, and arrow R indicates the right side of the vehicle.

[0042] like Figure 1 As shown, the riding type vehicle 1 is constituted by mounting an engine 30, an electric system and other various components on a cradle-type body frame 10. The body frame 10 includes a main pipe 12 extending rearward from a head pipe 11 and then bending downward, and a down pipe 13 extending downward from the head pipe 11 and then bending rearward. The rear side of the engine 30 is supported by the main pipe 12, and the front side and the lower side of the engine 30 are supported by the down pipe 13. A fuel tank 17 is supported on the main pipe 12, and a rider seat 18 and a pillion seat 19 are provided behind the fuel tank 17.

[0043] A pair of front forks 21 are supported on the head pipe 11 via a steering shaft (not shown) in a steerable manner, and a front wheel 22 is supported on the lower part of the front fork 21 in a rotatable manner. A swing arm (not shown) is supported on the rear half of the main pipe 12 in a swingable manner, and a rear wheel 23 is supported on the rear end of the swing arm in a rotatable manner. The engine 30 is connected to the rear wheel 23 via a speed change mechanism, and the power from the engine 30 is transmitted to the rear wheel 23 via the speed change mechanism. The exhaust device 50 is connected to the engine 30, and the exhaust gas from the engine 30 is discharged to the outside through the exhaust device 50.

[0044] In addition, in order to cope with the exhaust gas regulations in recent years, methods such as increasing the catalyst capacity of the catalyst housing arranged below the engine, and arranging a primary catalyst housing in front of the engine and arranging a secondary catalyst housing below the engine are used. In these methods, the lower part of the engine is used to increase the catalyst capacity, and it is difficult to ensure a sufficient volume of the silencer chamber at a position upstream of the muffler without changing the basic structure of the vehicle body frame and the engine. As a result, the muffler is enlarged, the degree of freedom of design of the muffler appearance is reduced, and the impact of heat damage to the rider or other parts is increased.

[0045] Therefore, in the exhaust device 50 of the present embodiment, the space in front of the engine 30 and the front side of the space below the engine 30 are effectively utilized, and the catalyst housing is compactly arranged in front of the engine 30 compared with a general exhaust device. A chamber 71 having only a muffler function and not having a catalyst arranged therein is arranged in the space below the engine 30 (see FIG. Figure 3 ), the chamber 71 is used to ensure a sufficient volume of the silencer chamber upstream of the muffler 82. As a result, the changes to the basic structure of the vehicle body frame 10 and the engine 30 can be suppressed to a minimum, and the silencer chamber in the muffler 82 can be reduced, thereby miniaturizing the muffler 82.

[0046] Below, refer to Figures 2 to 4 The engine and exhaust system are described. Figure 2 It is a front view of the engine of this embodiment. Figure 3 It is a side view of the engine of this embodiment. Figure 4 It is a bottom view of the engine of this embodiment.

[0047] like Figure 2 and Figure 3As shown, the engine 30 is a parallel two-cylinder engine, which is composed of a cylinder block 32, a cylinder head 33, and a cylinder head cover 34 assembled on a crankcase 31. The crankcase 31 accommodates driving components such as a crankshaft 35, and the cylinder block 32 is installed on the upper part of the crankcase 31. The cylinder block 32 is formed with a pair of cylinder bores (not shown) arranged in the left-right direction (engine width direction), and a piston (not shown) connected to the crankshaft 35 is arranged in each cylinder bore. The cylinder head 33 is installed on the upper part of the cylinder block 32.

[0048] A pair of intake ports (not shown) connected to a pair of cylinder bores are formed on the back side of the cylinder head 33, and a pair of exhaust ports 36L and 36R connected to a pair of cylinder bores are formed on the front side of the cylinder head 33. A cylinder head cover 34 is mounted on the upper part of the cylinder head 33, and a valve train and the like are accommodated in the cylinder head 33 and the cylinder head cover 34. An oil pan 37 for storing oil for lubrication and cooling is mounted on the lower part of the crankcase 31. An oil filter 38 for removing foreign matter from the oil is mounted on the lower part of the front surface of the crankcase 31.

[0049] The engine 30 is assembled inside the vehicle body frame 10. The down tube 13 of the vehicle body frame 10 has a head tube 11 (see Figure 1 ) An upper down tube 14 extending downward from the left-right center of the engine 30, and a pair of lower down tubes 15L and 15R branching to the left and right from the lower end of the upper down tube 14 and extending obliquely downward. The lower down tubes 15L and 15R are bent rearward below the engine 30, and are joined to the main tube 12 at the rear ends of the lower down tubes 15L and 15R. The above-mentioned oil filter 38 is positioned between the lower down tubes 15L and 15R.

[0050] An exhaust device 50 is provided, and a pair of exhaust pipes 51L and 51R of the exhaust device 50 extend from the front surface of the cylinder head 33 in a manner avoiding the upper down pipe 14 and the lower down pipes 15L and 15R, and guide the exhaust gas from the exhaust pipes 51L and 51R to the muffler 82 at the rear of the engine 30. A small primary catalyst 54 that functions as a starter catalyst and a large secondary catalyst 62 that functions as a main catalyst are provided in the exhaust device 50. Exhaust gas enters the exhaust device 50 from the exhaust ports 36L and 36R, and atmospheric pollutants such as carbon monoxide (CO), hydrocarbons (HC), and nitrogen compounds (NOx) in the exhaust gas are purified by the primary catalyst 54 and the secondary catalyst 62.

[0051] The exhaust device 50 uses exhaust pipes 51L, 51R, a collection pipe 52, a primary catalytic housing 53, a bent pipe 55, a secondary catalytic housing 61, a chamber 71, an exhaust pipe 81, and a muffler 82 to form an exhaust passage that goes from the front of the engine 30 to the bottom and extends to the rear. The exhaust pipe 51L extends forward from the exhaust port 36L and is connected to the collection pipe 52. The exhaust pipe 51R extends forward from the exhaust port 36R and then extends to the left and is connected to the collection pipe 52. In this way, the exhaust pipe 51L is formed shorter than the exhaust pipe 51R, and the pipe lengths of the exhaust pipes 51L and 51R are given a difference. In addition, the exhaust pipes 51L and 51R have circular cross-sections.

[0052] The upstream side of the manifold 52 is divided into two branches, and the downstream side of the manifold 52 is formed into a cylindrical shape. Exhaust pipes 51L and 51R are connected to the upstream side of the manifold 52, and a primary catalytic shell 53 is connected to the downstream end of the manifold 52. The exhaust gas passing through the exhaust pipes 51L and 51R is collected by the manifold 52 and transported to the primary catalytic shell 53. A first oxygen sensor 83 is arranged on the wall surface of the manifold 52 between the exhaust pipes 51L and 51R, and the first oxygen sensor 83 is used to detect the average oxygen concentration of the exhaust gas flowing in from the exhaust pipes 51L and 51R. The detection result of the first oxygen sensor 83 is used for feedback control of the fuel injection amount.

[0053] The primary catalytic shell 53 is formed in a cylindrical shape and is connected to the manifold 52 in a substantially longitudinal posture. Since the exhaust pipe 51L is shorter than the exhaust pipe 51R, the primary catalytic shell 53 and the manifold 52 are arranged at a position on the left side (one side in the engine width direction) of the center line C1 of the engine 30 extending in the vertical direction. The primary catalyst 54 for purifying the exhaust gas passing through the exhaust pipes 51L and 51R is accommodated in the primary catalytic shell 53. The primary catalyst 54 is a catalyst having a catalyst material attached to the surface of a honeycomb or lattice partition plate. When the exhaust gas flowing in from the manifold 52 passes through the primary catalyst 54, the atmospheric pollutants react with oxygen and are purified.

[0054] Since the exhaust pipe 51L is short, the high-temperature exhaust gas flows from the exhaust port 36L into the primary catalytic housing 53, and the primary catalyst 54 in the primary catalytic housing 53 is preheated in a short time, and the purification performance of the exhaust gas from the exhaust port 36L is improved. In this case, the exhaust pipe 51R is long, and the temperature of the exhaust gas is easy to drop, but the primary catalyst 54 is preheated in a short time by the high-temperature exhaust gas from the exhaust pipe 51L, and the purification performance of the exhaust gas from the exhaust port 36R is also improved. In this way, by intentionally giving the exhaust pipes 51L and 51R a difference in pipe length, the primary catalyst 54 is activated in advance.

[0055] The curved pipe 55 is formed into an L-shaped tube that connects the longitudinal cylinder portion 56 on the upstream side and the transverse cylinder portion 57 on the downstream side. The cross-sectional shape of the curved pipe 55 gradually changes from a circle to an oblong shape from the upstream end toward the downstream end. The primary catalytic shell 53 is connected to the upstream end of the longitudinal cylinder portion 56 with a circular cross section, and the secondary catalytic shell (catalytic shell) 61 is connected to the downstream end of the transverse cylinder portion 57 with an oblong cross section. The exhaust gas that has passed through the primary catalyst 54 is guided by the curved pipe 55 to the secondary catalyst 62 below the engine 30. A second oxygen sensor 84 is arranged on the wall surface of the transverse cylinder portion 57, and the second oxygen sensor 84 is used to detect the oxygen concentration of the exhaust gas that has passed through the primary catalytic shell 53. The detection result of the second oxygen sensor 84 is used for feedback control of the fuel injection amount and diagnosis of catalyst degradation.

[0056] like Figure 3 and Figure 4 As shown, the secondary catalytic housing 61 is formed in a long cylindrical shape and is connected to the bent pipe 55 in a substantially horizontal posture. At this time, the secondary catalytic housing 61 extends obliquely rearward from the left side to the right side (from one side to the other side in the engine width direction). The secondary catalytic housing 61 contains a secondary catalyst 62 for purifying the exhaust gas passing through the bent pipe 55. The secondary catalyst 62 is a catalyst having a catalyst material attached to the surface of a honeycomb or lattice partition plate. When the exhaust gas flowing in from the bent pipe 55 passes through the secondary catalyst 62, the atmospheric pollutants react with oxygen and are purified.

[0057] The chamber 71 is formed in a long cylindrical shape and is connected to the secondary catalyst housing 61 in a substantially horizontal posture. A muffler chamber 72 for reducing exhaust noise is formed in the chamber 71 (see Figure 6 The chamber 71 extends in the front-to-rear direction and is joined in such a way that the upstream end of the chamber 71 covers the outer wall surface of the secondary catalytic housing 61. The chamber 71 is arranged on the right side (the other side in the engine width direction) of the center line C2 of the engine 30 extending in the front-to-rear direction. A tapered pipe 73 connected to the downstream end of the secondary catalytic housing 61 and a punching pipe 74 connected to the downstream end of the tapered pipe 73 are provided inside the chamber 71.

[0058] The cross-sectional shape of the tapered tube 73 gradually changes from an oblong shape to a circular shape from the upstream end toward the downstream end. A plurality of small holes are formed on the peripheral surface of the perforated tube 74, and the inner side of the perforated tube 74 and the muffler chamber 72 are connected through the plurality of small holes. When the exhaust gas enters the muffler chamber 72 from the perforated tube 74, the exhaust gas expands in the muffler chamber 72, thereby reducing the exhaust sound. In addition, the outer wall of the chamber 71 is a double-tube structure, and the gap between the inner tube and the outer tube is filled with glass wool for sound absorption. The chamber 71 is supported on the vehicle body frame 10 via a bracket 75.

[0059] The exhaust pipe 81 is formed in a cylindrical shape and extends rearward from the downstream end of the chamber 71. Figure 1 ) is located on the right side of the rear wheel 23 and is connected to the downstream end of the exhaust pipe 81. A muffler chamber (not shown) for reducing exhaust noise is formed in the muffler 82, and the rear end of the muffler chamber is connected to the outside through the exhaust port. The structure of the muffler 82 is not particularly limited, and one muffler chamber or a plurality of muffler chambers may be formed inside the muffler 82. In this way, in the exhaust device 50, the exhaust noise is reduced in two stages by the chamber 71 and the muffler 82.

[0060] Reference Figures 2 to 6 , the configuration structure of the catalyst shell and chamber is explained. Figure 5 Yes Figure 4 Section view along line AA. Figure 6 Yes Figure 4 A cross-sectional view taken along line BB. Figure 5 The description in omits the primary catalyst.

[0061] like Figure 2 As shown in FIG. 1 , the lower down tubes 15L and 15R branch from the lower end of the upper down tube 14 and extend obliquely downward. The branching portion of the lower down tubes 15L and 15R is located below the exhaust ports 36L and 36R and above the height position O1 of the center of the crankshaft 35. An oil filter 38 is provided in a V-shaped space between the lower down tubes 15L and 15R on the front surface of the crankcase 31. The oil filter 38 is located on the center line C1 of the engine 30 extending in the vertical direction. Since the exhaust device 50 is provided in a manner avoiding the front of the oil filter 38, an entry path for the tool relative to the oil filter 38 is ensured.

[0062] An oil pan 37 is attached to the lower surface of the crankcase 31. The left side (one side in the engine width direction) of the bottom surface of the oil pan 37 is formed as a deep bottom, and the bottom surface of the oil pan 37 is inclined so as to become shallower from the deep bottom portion 41 toward the right side (the other side in the engine width direction) (see Figure 6 ). The right side of the bottom surface of the oil pan 37 is recessed in an arch shape, and the exhaust device 50 is arranged in a manner passing through the recess of the oil pan 37. In this way, a configuration space for the exhaust device 50 is formed below the engine 30 at a position to the right of the deep bottom portion 41 of the oil pan 37. In addition, the detailed situation of the positional relationship between the exhaust device 50 and the oil pan 37 will be described later.

[0063] like Figure 2 and Figure 3As shown, the primary catalytic housing 53 is arranged in front of the lower down tube 15L. The upstream end of the primary catalytic housing 53 is roughly consistent with the height position O1 of the center of the crankshaft 35. The bent pipe 55 is bent into an L shape in a manner from the downstream end of the primary catalytic housing 53 toward the right side, and the downstream end of the bent pipe 55 is located below the oil filter 38. By extending the bent pipe 55 obliquely to reduce the occupied area in the front and rear, the secondary catalytic housing 61 connected to the downstream end of the bent pipe 55 is compactly arranged in the front. The rearmost part of the downstream end of the secondary catalytic housing 61 is roughly consistent with the front and rear position O2 of the center of the crankshaft 35.

[0064] like Figure 4 As shown in FIG. 1 , a secondary catalyst housing 61 is arranged between the lower down tubes 15L and 15R in a manner overlapping with the oil pan 37. The secondary catalyst housing 61 extends obliquely rearward from the left side toward the right side, and the secondary catalyst housing 61 intersects with the center line C2 of the engine 30 extending in the front-rear direction. By arranging the secondary catalyst housing 61 obliquely, the occupied area of ​​the secondary catalyst housing 61 in the front-rear direction can be reduced, and a larger occupied area of ​​the chamber 71 can be ensured behind the secondary catalyst housing 61. The secondary catalyst 62 housed inside the secondary catalyst housing 61 is also arranged obliquely like the secondary catalyst housing 61.

[0065] The chamber 71 extends in the front-to-back direction and is arranged at a position to the right of the center line C2 of the engine 30 extending in the front-to-back direction. The upstream end of the chamber 71 is located at a position forward of the front-to-back position O2 of the center of the crankshaft 35, and the downstream end of the chamber 71 extends to the bridge portion 16 connecting the lower down tubes 15L and 15R. The full length of the chamber 71 is set to a size that does not interfere with the center bracket (not shown). No catalyst is contained in the muffler chamber 72 in the chamber 71, and the muffler chamber 72 becomes an expansion space for exhaust gas. The chamber 71 functions as a primary muffler that assists the muffler function of the muffler 82.

[0066] The upstream end of the chamber 71 is joined to the outer wall surface of the secondary catalytic shell 61, thereby ensuring a larger silencer chamber 72 in the chamber 71, thereby improving the silencer performance. In more detail, the chamber 71 is continuously connected to the secondary catalytic shell 61, and the space around the tapered pipe 73 (radially outward) disposed inside the chamber 71 is also used as the silencer chamber 72. There are no other components such as a connecting pipe between the secondary catalytic shell 61 and the chamber 71, and the secondary catalytic shell 61 is directly connected to the chamber 71, thereby allowing the exhaust gas to flow smoothly from the secondary catalytic shell 61 to the chamber 71.

[0067] Thus, the primary catalytic housing 53 is arranged in the front space of the engine 30, the secondary catalytic housing 61 is arranged in the front side of the lower space of the engine 30, and the chamber 71 is arranged in the rear side of the lower space of the engine 30. More specifically, most of the primary catalytic housing 53 is arranged in the front of the engine 30 at a position lower than the center of the crankshaft 35, and most of the secondary catalytic housing 61 is arranged in the front of the center of the crankshaft 35 (see FIG. Figure 3 ). Moreover, most of the chamber 71 is arranged below the engine 30 at a position behind the center of the crankshaft 35, and a muffler chamber 72 of sufficient volume is ensured behind the space below the engine 30 in the exhaust passage (see Figure 6 ).

[0068] In the exhaust device 50, the necessary volume of the silencer chamber is ensured by the chamber 71 and the muffler 82. The chamber 71 functions as a primary muffler, so that the volume of the muffler 82 downstream of the chamber 71 can be reduced. While maintaining the muffler performance of the exhaust device 50, the risk of thermal damage caused by the reduction in the surface area of ​​the muffler 82 is reduced, and the degree of freedom in the design of the muffler 82 is improved. In addition, the high-temperature catalyst is concentrated near the engine 30, thereby reducing the risk of thermal damage. Moreover, the center of gravity of the secondary catalyst 62 is located at a position forward of the center of the crankshaft 35, so that the weight balance is optimized.

[0069] like Figure 5 As shown, the secondary catalytic housing 61 is positioned inside the arch-shaped recess of the oil pan 37. The secondary catalytic housing 61 has an oblong cross-sectional shape in which the width is larger than the height. The long diameter of the secondary catalytic housing 61 is oriented in a substantially horizontal direction, and the short diameter of the secondary catalytic housing 61 is oriented in a substantially vertical direction. The upper surface 63 of the secondary catalytic housing 61 is opposed to the bottom surface 42 of the oil pan 37 over a large range, and heat dissipated from the upper surface 63 of the secondary catalytic housing 61 is transferred to the bottom surface 42 of the oil pan 37. In addition, the side surface 64 of the secondary catalytic housing 61 is opposed to the inclined portion 43 of the oil pan 37, and heat dissipated from the side surface 64 of the secondary catalytic housing 61 is transferred to the inclined portion 43 of the oil pan 37.

[0070] like Figure 6 As shown, the chamber 71 is positioned inside the arched recess of the oil pan 37. The chamber 71 has an oblong cross-sectional shape in which the width dimension is larger than the height dimension. The long diameter of the chamber 71 is oriented in a substantially horizontal direction, and the short diameter of the chamber 71 is oriented in a substantially vertical direction. The upper surface 76 of the chamber 71 is opposed to the bottom surface 42 of the oil pan 37 over a large range, and the heat dissipated from the upper surface 76 of the chamber 71 is transferred to the bottom surface 42 of the oil pan 37. In addition, the side surface 77 of the chamber 71 is opposed to the inclined portion 43 of the oil pan 37, and the heat dissipated from the side surface 77 of the chamber 71 is transferred to the inclined portion 43 of the oil pan 37.

[0071] When viewed from the front, the secondary catalyst housing 61 overlaps with the deep bottom portion 41 of the oil pan 37 (see Figure 2 ). More specifically, the secondary catalyst housing 61 crosses in front of the deep bottom portion 41 of the oil pan 37 (see Figure 4 ), the heat dissipated by the secondary catalyst housing 61 is transferred to the oil pan 37 by the running wind. The heat dissipated from the secondary catalyst housing 61 and the chamber 71 is transferred to the oil pan 37, so that the oil in the oil pan 37 is raised to an appropriate temperature in a short time. Since the minor diameter (height) of the secondary catalyst housing 61 and the chamber 71 is formed small, the engine 30 is arranged low to improve the vehicle body stability during running, and it is easy to ensure the capacity of the fuel tank and the air filter.

[0072] Next, refer to Figure 2 and Figure 3 , the configuration structure of the first and second oxygen sensors is described.

[0073] like Figure 2 and Figure 3 As shown, the first oxygen sensor 83 is arranged in the manifold 52 in front of the engine 30. The first oxygen sensor 83 is erected in the manifold 52 between the exhaust pipes 51L and 51R in a state facing rearward (toward the engine 30). Since the first oxygen sensor 83 is sandwiched between the exhaust pipes 51L and 51R, the first oxygen sensor 83 is close to the engine 30, and the first oxygen sensor 83 is activated in advance by heat dissipation from the exhaust pipes 51L, 51R and the engine 30. The exhaust gas from the exhaust pipes 51L and 51R contacts the detection end of the first oxygen sensor 83 approximately uniformly, and the detection accuracy of the oxygen concentration by the first oxygen sensor 83 is improved.

[0074] Since the first oxygen sensor 83 is arranged on the inner side of the manifold 52, the manifold 52 protects the first oxygen sensor 83 from flying objects from the front. Since there is a bent pipe 55 below the first oxygen sensor 83, the bent pipe 55 protects the first oxygen sensor 83 from flying objects from below. The upper down tube 14 is located on the right side of the first oxygen sensor 83, and when viewed from the side, the first oxygen sensor 83 overlaps with the upper down tube 14. Therefore, by laying the wiring along the upper down tube 14, the wiring can be easily connected to the first oxygen sensor 83.

[0075] The second oxygen sensor 84 is disposed in the horizontal cylinder portion 57 downstream of the curved portion of the curved pipe 55. The second oxygen sensor 84 is vertically disposed in the horizontal cylinder portion 57 in a state of facing upward (toward the engine 30). By bringing the second oxygen sensor 84 close to the engine 30, the second oxygen sensor 84 is activated in advance by heat dissipation from the engine 30. In addition, when viewed from the front, the second oxygen sensor 84 overlaps with the vertical cylinder portion 56 upstream of the curved portion of the curved pipe 55. The second oxygen sensor 84 is protected from flying objects from below by the horizontal cylinder portion 57, and is protected from flying objects from above by the vertical cylinder portion 56.

[0076] The second oxygen sensor 84 is located between the lower down tubes 15L and 15R, and overlaps with the lower down tubes 15L and 15R when viewed from the side. The lower down tubes 15L and 15R protect the second oxygen sensor 84 from flying objects from the left and right sides. By placing the second oxygen sensor 84 close to the left side, the wiring is laid along the lower down tube 15L, so that the wiring is easily connected to the second oxygen sensor 84. Since the first and second oxygen sensors 83 and 84 are arranged on the left side of the engine 30, the left-right deviation of the first and second oxygen sensors 83 and 84 is reduced, and the wiring is easily concentrated.

[0077] The oil filter 38 is located on the right side of the second oxygen sensor 84, and the second oxygen sensor 84 overlaps with the oil filter 38 when viewed from the side. The oil filter 38 protects the second oxygen sensor 84 from flying objects from the right direction. In addition, the oil filter 38 protrudes forward from the front surface of the crankcase 31, and the second oxygen sensor 84 is located rearward compared to the front end of the oil filter 38. As a result, the second oxygen sensor 84 protruding directly upward from the horizontal cylinder 57 does not cross the space in front of the oil filter 38, and the entry path of the tool relative to the oil filter 38 is ensured.

[0078] As described above, according to the present embodiment, the secondary catalytic housing 61 is arranged at the front side of the lower space of the engine 30, and the lower space of the engine 30 is not occupied by the secondary catalytic housing 61. The chamber 71 is arranged in a large area of ​​the lower space of the engine 30, and the muffler chamber 72 of the chamber 71 is used to reduce the exhaust sound. By ensuring the muffler chamber 72 on the upstream side of the muffler 82, the muffler 82 can be miniaturized. Therefore, while maintaining the muffler performance, the risk of thermal damage to the surface of the muffler is reduced by miniaturizing the muffler 82, and the degree of freedom of design of the appearance of the muffler can be increased.

[0079] In addition, in this embodiment, the chamber is located on the right side of the deep bottom portion of the oil pan, but the shape of the chamber is not particularly limited. For example, if the mounting portion of the central bracket can be moved, Figure 7As shown in the modified example, the rear portion of the chamber 90 may protrude to the left behind the oil pan 37, thereby ensuring a larger silencer chamber in the chamber 90. In this case, the muffler on the side of the rear wheel can be removed, achieving mass centralization, reducing the risk of heat damage to the muffler surface, and improving the degree of freedom in the design of the muffler appearance.

[0080] In addition, in the present embodiment, most of the secondary catalytic housing is arranged at a position closer to the front side than the center of the crankshaft, but it is sufficient as long as the secondary catalytic housing is arranged in the range from the front space of the engine to the front side of the lower space. For example, the secondary catalytic housing can also be arranged in the front space of the engine. Thus, by arranging the chamber in a large range in the lower space of the engine, the silencing performance can be further improved. In addition, the front side of the lower space of the engine refers to the space in the lower space of the engine that is closer to the front side than the middle position in the front-to-back direction.

[0081] In addition, in the present embodiment, most of the chamber is arranged at a position behind the center of the crankshaft, but it is sufficient as long as the chamber is arranged to occupy at least the rear side of the lower space of the engine. For example, the chamber may be arranged at the front side and the rear side of the lower space of the engine. In addition, the rear side of the lower space of the engine refers to the space behind the middle position in the front-rear direction in the lower space of the engine.

[0082] In addition, in this embodiment, a punched part can also be used for the pipe of the exhaust device, so that the number of parts and welding locations can be reduced.

[0083] In addition, in this embodiment, the left side of the bottom surface of the oil pan is formed as a deep bottom, but a part of the bottom surface of the oil pan can be formed as a deep bottom. For example, as long as the exhaust device does not interfere with the oil pan, the right side of the bottom surface of the oil pan can also be formed as a deep bottom.

[0084] In addition, in the present embodiment, the upstream end of the chamber is joined to the outer wall surface of the secondary catalyst housing, but the chamber and the secondary catalyst housing may be separated and connected via a connecting pipe.

[0085] In addition, in the present embodiment, the primary catalytic casing and the secondary catalytic casing are provided in the exhaust device, but at least one catalytic casing may be provided in the exhaust device.

[0086] In addition, in the present embodiment, the structure in which the engine is a parallel two-cylinder engine is exemplified, but the type of the engine is not particularly limited, and for example, the engine may be a single-cylinder engine.

[0087] In addition, in this embodiment, the cross-sectional shape of the secondary catalytic housing and the chamber is formed into an oblong shape, but the cross-sectional shape of the secondary catalytic housing and the chamber can be formed into a cross-sectional shape in which the width is larger than the height. In addition, the cross-sectional shape of the secondary catalytic housing and the chamber can also be formed into a circular shape according to the frame shape, the engine bottom shape and the minimum ground height.

[0088] In addition, in this embodiment, the secondary catalyst housing crosses in front of the deep bottom portion of the oil pan, but the positional relationship between the secondary catalyst housing and the deep bottom portion of the oil pan is not particularly limited. In addition, when the heat dissipated from the secondary catalyst housing is transferred to the oil pan by the running wind, the secondary catalyst housing can be arranged so as to overlap with the deep bottom portion of the oil pan when viewed from the front.

[0089] In addition, in the present embodiment, the secondary catalyst housing extends obliquely rearward from the left side toward the right side, but the secondary catalyst housing may also extend in the front-rear direction.

[0090] In the present embodiment, an oxygen sensor is exemplified as the gas sensor, but the gas sensor may be any gas sensor that can detect the average characteristics of the exhaust gas, and for example, may be an exhaust sound sensor that detects the exhaust sound of the exhaust gas.

[0091] In addition, the exhaust device of this embodiment is not limited to the engine of the riding vehicle described above, and can also be used for the engine of other types of riding vehicles. In addition, the riding vehicle is not limited to a two-wheeled motor vehicle, as long as it is a vehicle equipped with an engine. In addition, the riding vehicle is not limited to all vehicles in which the driver rides in a posture of sitting astride a seat, and also includes a pedal-type vehicle in which the driver does not sit astride a seat.

[0092] As described above, the exhaust device 50 of the present embodiment is an exhaust device that guides exhaust gas from the exhaust pipes 51L and 51R in front of the engine 30 to the muffler 82 in the rear of the engine. It is provided with a catalytic shell (secondary catalytic shell 61) that accommodates a catalyst (secondary catalyst 62) for purifying the exhaust gas that has passed through the exhaust pipe, and a chamber 71 formed with a muffler chamber 72 for reducing exhaust noise at the downstream of the catalytic shell. The catalytic shell is arranged in a range from the front space of the engine to the front side of the lower space, and the chamber is arranged to occupy at least the rear side of the lower space of the engine. According to this structure, the catalytic shell is arranged in the front side of the front space of the engine or the lower space, and the lower space of the engine is not occupied by the catalytic shell. The chamber is arranged in a large range of the lower space of the engine, and the exhaust noise is reduced by the muffler chamber of the chamber. By ensuring the muffler chamber on the upstream side of the muffler, the muffler can be miniaturized. Therefore, while maintaining the muffler performance, the risk of thermal damage to the surface of the muffler is reduced by miniaturization of the muffler, and the degree of freedom of design of the appearance can be improved.

[0093] In the exhaust device of this embodiment, the front space of the engine is located in front of the engine and below the center of the crankshaft 35, the front side of the lower space of the engine is located below the engine and in front of the center of the crankshaft, and the rear side of the lower space of the engine is located below the engine and in rear of the center of the crankshaft. According to this structure, the chamber can be arranged in a wide range of the lower space of the engine according to the amount of the catalyst housing arranged in the position in front of the center of the crankshaft.

[0094] In the exhaust device of this embodiment, the upstream end of the chamber is located in front of the center of the crankshaft. According to this structure, a large muffler room of the chamber can be ensured.

[0095] In the exhaust device of this embodiment, the upstream end of the chamber is joined to the outer wall surface of the catalyst housing. According to this structure, the upstream end of the chamber can be extended to the catalyst housing to ensure a larger muffler chamber. In addition, the exhaust gas from the catalyst can flow smoothly into the chamber.

[0096] In the exhaust device of this embodiment, the catalyst housing extends obliquely rearward from one side to the other side in the engine width direction. According to this structure, by arranging the catalyst housing obliquely, the area occupied by the catalyst housing in the front-rear direction can be reduced, and a larger area occupied by the chamber can be ensured behind the catalyst housing.

[0097] In the exhaust device of this embodiment, the catalyst housing and the chamber have a cross-sectional shape in which the width is larger than the height. According to this structure, the engine can be arranged at a low level to improve the vehicle body stability during driving.

[0098] In the exhaust device of this embodiment, an oil pan 37 for storing oil is provided at the lower part of the engine, and the upper surfaces 63 and 76 of the catalyst housing and the chamber face the bottom surface 42 of the oil pan. According to this structure, heat dissipated from the upper surfaces of the catalyst housing and the chamber is transferred to the bottom surface of the oil pan, and the oil in the oil pan can be raised to an appropriate temperature in a short time.

[0099] In the exhaust device of this embodiment, a part of the bottom surface of the oil pan is formed into a deep bottom, and when viewed from the front, the catalyst housing overlaps with the deep bottom portion 41 of the oil pan. According to this structure, the heat dissipated from the catalyst housing is transferred to the oil pan by the running wind, and the oil in the oil pan can be raised to an appropriate temperature in a short time.

[0100] In the exhaust device of this embodiment, the catalyst housing is arranged to cross in front of the deep bottom portion. According to this structure, the heat dissipated from the catalyst housing is largely transferred to the oil pan by the traveling wind, and the oil in the oil pan can be raised to an appropriate temperature in a short time.

[0101] In the exhaust device of this embodiment, a deep bottom portion is formed on one side of the bottom surface of the oil pan in the engine width direction, and the bottom surface of the oil pan is inclined so as to become shallower from the deep bottom portion toward the other side in the engine width direction, and the side surfaces 64 and 77 of the catalyst housing and the chamber face the inclined portion 43 of the bottom surface of the oil pan. According to this structure, heat dissipated from the side surfaces of the catalyst housing and the chamber is transferred to the inclined portion of the bottom surface of the oil pan, and the oil in the oil pan can be raised to an appropriate temperature in a short time.

[0102] Furthermore, although the present embodiment has been described, the above-described embodiment and modified examples may be combined in whole or in part as other embodiments.

[0103] In addition, the technology of the present invention is not limited to the above-mentioned embodiments, and various changes, substitutions, and deformations can be made within the scope of the main purpose of the technical idea. Furthermore, as long as the technical idea can be realized in other ways through technological progress or other derived technologies, the method can also be used for implementation. Therefore, the scope of the request for protection covers all implementation methods that can be included in the scope of the technical idea.

Claims

1. An exhaust device that guides exhaust gas from an exhaust pipe in front of an engine to a muffler in the rear of the engine, characterized in that: have: a catalyst housing that houses a catalyst for purifying exhaust gas that has passed through the exhaust pipe; and a chamber having a muffler chamber for reducing exhaust noise formed downstream of the catalyst housing, the chamber being arranged on one side of a center line of the engine extending in the front-rear direction, The catalytic housing includes a secondary catalytic housing, which extends obliquely rearward from one side toward the other side in the width direction of the engine and is arranged to intersect with the center line. The catalyst housing is arranged in a range from a space in front of the engine to a front side of a space below the engine. The chamber is configured to occupy at least a rear side of a space below the engine.

2. The exhaust device according to claim 1, characterized in that: The space in front of the engine is located below the center of the crankshaft in front of the engine. The front side of the space below the engine is located below the engine and is closer to the front side than the center of the crankshaft. The rear side of the space below the engine is located behind the center of the crankshaft below the engine.

3. The exhaust device according to claim 2, characterized in that: An upstream end of the chamber is located forward of a center of the crankshaft.

4. The exhaust device according to claim 1, characterized in that: The upstream end of the chamber is joined to the outer wall surface of the secondary catalyst housing.

5. The exhaust device according to claim 1, characterized in that: The secondary catalytic housing and the chamber have a cross-sectional shape having a width greater than a height.

6. The exhaust device according to any one of claims 1 to 5, characterized in that: An oil pan for storing oil is provided at the lower part of the engine. The upper surfaces of the secondary catalytic housing and the chamber are opposite to the bottom surface of the oil pan.

7. The exhaust device according to claim 6, characterized in that: A portion of the bottom surface of the oil pan is formed as a deep bottom. When viewed from the front, the secondary catalyst housing overlaps with a deep bottom portion of the oil pan.

8. The exhaust device according to claim 7, characterized in that: The secondary catalytic housing traverses in front of the deep bottom portion.

9. The exhaust device according to claim 7, characterized in that: The deep bottom portion is formed on one side of the bottom surface of the oil pan in the engine width direction, and the bottom surface of the oil pan is inclined so as to become shallower from the deep bottom portion toward the other side in the engine width direction. The secondary catalyst housing and the side surfaces of the chamber are opposed to the inclined portion of the bottom surface of the oil pan.

10. The exhaust device according to claim 8, characterized in that: The deep bottom portion is formed on one side of the bottom surface of the oil pan in the engine width direction, and the bottom surface of the oil pan is inclined so as to become shallower from the deep bottom portion toward the other side in the engine width direction. The secondary catalyst housing and the side surfaces of the chamber are opposed to the inclined portion of the bottom surface of the oil pan.

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