JP2018178731A - Exhaust device of saddle type vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance sound insulation performance of a chamber, even with configuration configured to store a plurality of catalyst devices in the chamber, and to early activate catalyst without making a structure complicated.SOLUTION: An exhaust device includes an exhaust pipe attached to an engine of a motorcycle, a chamber 41 connected to a downstream side of the exhaust pipe, a muffler connected to the chamber 41, and two columnar catalyst devices 46, 47 provided in the chamber 41 and configured to purify exhaust air. The catalyst devices 46, 47 are arranged side by side at a gap G1 in a horizontal direction of the motorcycle, and inflow side end parts 46A, 47A of the catalyst devices 46, 47 face to the forward side of the motorcycle, and are aligned in a front-back direction of the motorcycle.SELECTED DRAWING: Figure 6

Description

  The present invention relates to an exhaust system of a straddle-type vehicle provided with a catalyst device.

  In an exhaust system of a straddle-type vehicle equipped with a four-stroke engine, one having a chamber provided between an exhaust pipe and a muffler is known. According to this configuration, the chamber can have a muffling performance by increasing the volume of the chamber. Therefore, the muffler can be miniaturized.

  Further, with recent tightening of exhaust gas regulations, improvement of exhaust gas purification performance of the exhaust system is required. Some straddle-type vehicles have a configuration in which a plurality of catalyst devices are accommodated in a chamber. By using a plurality of catalyst devices, the exhaust gas purification performance of the exhaust system can be improved. Further, the degree of freedom of piping of the exhaust pipe can be increased by accommodating each catalyst device in the chamber.

  Patent Document 1 below describes an exhaust system in which a plurality of catalyst devices are accommodated in a chamber.

JP, 2010-270702, A

  However, by accommodating a plurality of catalyst devices in the chamber, the space for reducing the exhaust noise in the chamber is reduced. As a result, the muffling performance of the chamber is reduced. For this reason, in order to heighten the reduction effect of the exhaust noise by a muffler, it becomes necessary to enlarge a muffler. As the muffler becomes larger, it becomes difficult to secure the bank angle and weight balance of the saddle-ride type vehicle, or it becomes difficult to improve the appearance.

  In the exhaust system described in Patent Document 1, as shown in FIG. 8 of the document, the remaining space in the chamber accommodating portion after accommodating the first catalyst and the second catalyst in the chamber accommodating portion is small, And the remaining space is divided by the second catalyst. Therefore, the reduction effect of the exhaust noise obtained by the remaining space is considered to be low.

  On the other hand, in order to improve the exhaust gas purification performance of the exhaust system, it is required to achieve early activation of the catalyst at the time of engine start. Most exhaust systems in straddle-type vehicles employ a method of rapidly raising the temperature of the catalyst by applying high temperature exhaust gas to the catalyst to activate the catalyst early. When such a method is employed in a configuration provided with a plurality of catalyst devices, exhaust gas needs to be applied efficiently and evenly to each of the plurality of catalysts. However, it is not easy to realize a configuration in which exhaust is efficiently and evenly applied to each of a plurality of catalysts without complicating the structure of the exhaust system.

  In the exhaust system described in Patent Document 1, as shown in FIG. 5 of the document, a path for causing the exhaust gas to directly reach the first catalyst is formed by the exhaust pipe, and the exhaust gas directly reaches the second catalyst. The path to be made is formed by the bypass passage connected in the middle of the exhaust pipe. Thus, the exhaust system described in Patent Document 1 has a complicated exhaust pipe structure in order to apply exhaust to each of the plurality of catalysts.

  The present invention has been made in view of, for example, the problems as described above, and an object of the present invention is to enhance the muffling performance of the chamber while having a configuration for accommodating a plurality of catalyst devices in the chamber, and It is an object of the present invention to provide an exhaust system for a straddle-type vehicle which can achieve early activation of a catalyst without complication.

  In order to solve the above problems, an exhaust system of a straddle-type vehicle according to the present invention includes an exhaust pipe attached to an engine provided in a straddle-type vehicle, and a chamber connected downstream of the exhaust pipe. A muffler connected to the chamber, and a plurality of cylindrical catalyst devices provided in the chamber for purifying exhaust gas, the plurality of catalyst devices having a gap in the left-right direction of the saddle-ride type vehicle Each of the inflow side end portions is directed in front of the straddle-type vehicle, and the respective inflow side end portions are aligned in the front-rear direction of the straddle-type vehicle.

  According to the present invention, it is possible to enhance the muffling performance of the chamber and achieve early activation of the catalyst without complicating the structure, while having a configuration in which a plurality of catalyst devices are accommodated in the chamber.

FIG. 1 is an explanatory view showing a part of a motorcycle provided with an exhaust system according to an embodiment of the present invention. FIG. 2 is an explanatory view of a part of the motorcycle in FIG. 1 as viewed from below. It is a perspective view showing the exhaust system of the example of the present invention. It is an external view which shows the chamber in the exhaust system of the Example of this invention. It is sectional drawing which shows the chamber seen from the arrow VV direction in FIG. FIG. 6 is a cross-sectional view showing the chamber generally viewed in the direction of arrows VI-VI in FIG. 5; It is a perspective view which shows the catalyst apparatus, partition part, and support member which were provided in the chamber in the exhaust system of the Example of this invention. It is explanatory drawing which shows the modification of the exhaust apparatus of the Example of this invention. It is explanatory drawing which shows the other modification of the exhaust apparatus of the Example of this invention.

  An exhaust system of a straddle-type vehicle according to an embodiment of the present invention includes an exhaust pipe attached to an engine provided in a straddle-type vehicle, a chamber connected to the downstream side of the exhaust pipe, and a muffler connected to the chamber. And a plurality of catalytic devices for purifying the exhaust gas.

  The plurality of catalyst devices are each formed in a cylindrical shape. In addition, a plurality of catalyst devices are provided in the chamber, respectively. In the chamber, the plurality of catalyst devices are arranged side by side with a gap in the left-right direction of the saddle-ride type vehicle, and the respective inflow side ends face the front of the saddle-ride type vehicle and the respective inflow side ends Are aligned in the longitudinal direction of the straddle-type vehicle.

  According to the exhaust system of the straddle-type vehicle of the embodiment of the present invention, the plurality of catalyst devices are arranged side by side with a gap in the left-right direction of the straddle-type vehicle. The gap can be passed through the exhaust after passing through the inside of each catalyst device, which can enhance the exhaust noise reduction effect of the chamber.

  In addition, since a plurality of catalyst devices are arranged side by side with gaps in the left-right direction of the saddle-ride type vehicle, the outer circumferential surface of each catalyst device is utilized inside each catalyst device utilizing the gaps between the catalyst devices. The exhaust after passing through can be applied efficiently and evenly. Thereby, early activation of each catalyst device can be achieved by the heat of the exhaust gas. In addition, it is possible to prevent the activation of a part of the plurality of catalyst devices from being delayed. In addition, it is not necessary to construct a complicated route for leading the exhaust gas to the respective catalyst devices, such as adding a bypass passage to the exhaust pipe in order to evenly apply the exhaust gas to the respective catalyst devices.

  Further, since the inflow side end portions of the plurality of catalyst devices are aligned in the front-rear direction of the saddle-ride type vehicle, the exhaust gas flowing out from the exhaust pipe in front of the respective catalyst devices in the chamber is A space (inflow chamber) for inflow can be easily secured.

  Further, since the inflow side end portions of the plurality of catalyst devices are aligned in the longitudinal direction of the saddle-ride type vehicle, a large space can be easily secured behind the catalyst devices in the chamber, respectively. The muffling performance can be enhanced.

  In addition, cylindrical catalyst devices are available in the market for products of various sizes, and catalyst devices matching the size of the chamber can be easily selected. This increases the freedom of the catalyst device layout. Therefore, it becomes possible to easily set the layout of the catalyst device so as to ensure a large space in the chamber which exhibits a high exhaust noise reduction effect. In addition, the cost of the exhaust system can be reduced by selecting an inexpensive catalyst system provided in the market.

  FIG. 1 shows a part of a motorcycle 1 provided with an exhaust system according to an embodiment of the present invention. FIG. 2 is a view of a part of the motorcycle 1 in FIG. 1 as viewed from below. FIG. 3 shows an exhaust system 31 according to an embodiment of the present invention. The arrows drawn at the lower right of each of FIGS. 1 to 7 are front (F), rear (B), left (L), right (R), and top as viewed from the driver of the motorcycle 1. The directions of (U) and lower (D) are indicated. When the directions are described in the following embodiments, the directions indicated by these arrows are followed.

  In FIGS. 1 and 2, a vehicle body frame 2 of the motorcycle 1 includes a head pipe 3, a pair of main frames 4 and a pair of seat rails 5. The head pipe 3 is disposed on the front upper side of the motorcycle 1 as shown in FIG. 1 and is disposed at a lateral middle portion of the motorcycle 1 as shown in FIG. The pair of main frames 4 is, for example, a twin spar frame formed of aluminum alloy, and extends backward while respectively opening left and right from the head pipe 3 and then bends downward near the middle portion in the longitudinal direction of the motorcycle 1 The lower part of the motorcycle 1 is reached. The pair of seat rails 5 extend from the rear upper side of the left and right main frames 4 to the rear, respectively.

  Further, a swing arm 6 is vertically swingably supported at the lower rear side of the left and right main frames 4, and a rear wheel 7 is rotatably supported at the rear end side of the swing arm 6. Further, a rear suspension 8 is provided between the swing arm 6 and the rear upper side of the left and right main frames 4. The upper end portion of the rear suspension 8 is connected to the bracket portion 9 provided on the left and right main frames 4 respectively, and the lower end portion of the rear suspension 8 is connected to the swing arm 6 via the rear suspension link 10 . A side stand 11 is attached to the lower rear of the left main frame 4. In the motorcycle 1 shown in FIG. 1 or 2, the steering shaft, the front fork, the front wheel, the steering wheel, the fuel tank, the seat, the cowl and the like are not shown.

  In addition, for example, a parallel 4-cylinder four-stroke engine 21 is provided between the left and right main frames 4. The engine 21 includes a crankcase 22, a cylinder 23 provided on the crankcase 22, a cylinder head 24 provided on the cylinder 23, and an oil pan 25 provided on the lower part of the crankcase 22.

  In addition, the exhaust system 31 of the embodiment of the present invention is provided in the motorcycle 1. The exhaust device 31 is a device that discharges the exhaust from the engine 21 to the atmosphere, and has a function of purifying the exhaust and a function of reducing exhaust noise. As shown in FIG. 3, the exhaust device 31 has four exhaust pipes 33, 34, 35, 36 corresponding to the number of cylinders of the engine 21, a pair of collecting pipes 37, 38, a chamber 41, a pair of joint pipes 42, 43, a pair of mufflers 44, 45, two catalyst devices 46, 47, an exhaust gas sensor 48 and an exhaust valve 49 are provided.

  The inflow side ends of the four exhaust pipes 33, 34, 35, 36 are respectively connected to four exhaust ports disposed on the front surface of the cylinder head 24, as shown in FIG. The four exhaust pipes 33, 34, 35, 36 respectively curve from the exhaust port downward through the front of the cylinder 23 and the front of the crankcase 22 and then curve rearward. The outlet ends (downstream sides) of the four exhaust pipes 33, 34, 35, 36 are divided into two groups as shown in FIG. Connected to 38. That is, the outflow side ends of the two left exhaust pipes 33 and 34 are connected to each other and connected to the single left collective pipe 37. Further, the outflow side ends of the two right exhaust pipes 35, 36 are connected to each other and connected to one right collective pipe 38. In addition, the oil pan 25 has a shape in which the left and right direction middle portion at the lower part thereof protrudes downward. The outflow end sides of the exhaust pipes 33, 34, 35, 36 divided into two groups and the two collecting pipes 37, 38 sandwich the downwardly projecting portion (convex portion) 25A of the oil pan 25. It is plumbed. The outflow side ends of the two collecting pipes 37 and 38 are connected to the chamber 41, respectively.

  The chamber 41 is disposed at the lower portion of the middle portion of the motorcycle 1 in the front-rear direction. Specifically, the front of the chamber 41 is located below the crankcase 22 and behind the oil pan 25. The longitudinal middle portion of the chamber 41 is located below the pivot 12. The rear of the chamber 41 is located below the front of the swing arm 6, and the rear end of the chamber 41 reaches the position of the rear of the rear suspension link 10. Further, the chamber 41 is disposed at a lateral middle portion of the motorcycle 1.

  The joint pipes 42 and 43 are connected to the chamber 41 at their inflow end. The left joint pipe 42 extends from the chamber 41 to the left rear. The right joint pipe 43 extends rearward from the chamber 41 to the right. Further, the outflow side ends of the joint pipes 42 and 43 are connected to the mufflers 44 and 45, respectively. The mufflers 44 and 45 are respectively disposed on the left and right sides of the rear portion of the motorcycle 1.

  The two catalyst devices 46, 47 are respectively provided in the chamber 41 as shown in FIG. An exhaust gas sensor 48 is attached to the front of the chamber 41. The exhaust valve 49 is a valve for switching the exhaust flow rate, and is attached to the right joint pipe 43.

  FIG. 4 shows the chamber 41 in the exhaust system 31. FIG. 5 shows a cross section of the chamber 41 as viewed in the direction of arrows V-V in FIG. 6 shows a cross section of the chamber 41 generally viewed from the direction of arrows VI-VI in FIG. FIG. 7 shows the catalyst devices 46 and 47, the partition 61 and the support member 63.

  As shown in FIG. 4, the chamber 41 is formed in a box shape by four wall plates 51, 52, 53, 54 formed of metal plates. That is, the chamber 41 includes a front lower wall plate 51 forming the lower front wall, a front upper wall plate 52 forming the upper front wall, a lower wall, a lower left wall, a lower lower wall and a lower lower wall. A plate 53 and a rear upper wall plate 54 forming an upper wall, a left side wall upper portion, a right side wall upper portion and a rear wall upper portion are provided. These wall plates 51, 52, 53, 54 are respectively joined by welding.

  Further, a pair of mounting brackets 55 is provided on the left and right portions on the upper surface side of the rear upper wall plate 54 (see FIG. 3). The chamber 41 is supported by the mounting brackets 55 at lower portions of the left and right main frames 4 and at bridge portions 13 bridged between the main frames 4.

  Further, as shown in FIG. 6, a pair of collecting pipes is provided on the front left side and the front right side of the front wall of the chamber 41 formed by joining the front lower wall plate 51 and the front upper wall plate 52. A pair of inflow side connection holes 56 for connecting 37 and 38 are formed respectively. In addition, a left joint pipe connection hole 57 for connecting the left joint pipe 42 is provided at the rear of the left wall of the chamber 41 formed by joining the rear lower wall plate 53 and the rear upper wall plate 54. It is formed. In the rear of the right wall of the chamber 41 formed by joining the rear lower wall plate 53 and the rear upper wall plate 54, a right joint pipe connection hole 58 for connecting the right joint pipe 43 is provided. It is formed.

  Moreover, the chamber 41 is provided with the partition part 61 which divides the inside of the said chamber 41 in the front-back direction. The partition portion 61 is formed of metal in a plate shape. Further, the partitioning portion 61 is bent so that the edge thereof extends rearward along the entire circumference, for example, by press processing. The edge of the dividing portion 61 is between the rear end of the front lower wall plate 51 and the front end of the rear lower wall plate 53, and the rear end of the front upper wall plate 52 and the rear end of the rear upper wall plate 54. Between the front lower wall plate 51, the rear lower wall plate 53, the front upper wall plate 52, and the rear upper wall plate 54 by welding. The inflow chamber R1 is formed between the front wall of the chamber 41 and the partition portion 61 in the chamber 41 by the partition portion 61, and the outflow chamber R2 is formed between the partition portion 61 and the rear wall of the chamber 41. ing. Further, as shown in FIG. 7, a pair of insertion holes 62 for inserting the inflow side end portions 46A, 47A of the two catalyst devices 46, 47 are respectively formed in the left portion and the right portion of the partition portion 61. ing.

  As shown in FIG. 6, two catalytic devices 46, 47 are provided at the front of the outflow chamber R2. Each catalyst device 46, 47 is a three-way catalyst that purifies the exhaust gas. Each catalyst device 46, 47 is formed in a cylindrical shape, and one axial end side is the inflow side end 46A, 47A, and the other axial side is the outflow side end 46B, 47B. Also, the two catalyst devices 46, 47 are respectively the same product and have the same size.

  In the outflow chamber R2, the catalyst devices 46, 47 are respectively disposed on the front side of the middle position in the front-rear direction of the chamber 41. The catalyst devices 46 and 47 are arranged side by side with a gap G1 in the left-right direction. The catalyst devices 46 and 47 are arranged such that their axes are parallel to each other. In the catalyst devices 46 and 47, the inflow side end portions 46A and 47A face forward, and the respective inflow side end portions 46A and 47A are aligned in the front-rear direction. In addition, the catalyst devices 46 and 47 are disposed such that a gap G2 is formed between the outer peripheral surface of each and the wall surface in the chamber 41.

  The catalyst devices 46 and 47 are supported in the outflow chamber R2 by the insertion holes 62 and the support members 63 formed in the partition portion 61. That is, as shown in FIG. 7, the inflow side end portions 46A, 47A of the catalyst devices 46, 47 are respectively inserted into the insertion holes 62 of the partition 61 and fixed to the edge portions of the insertion holes 62 by welding or the like. Further, the outflow side end portions 46B and 47B of the catalyst devices 46 and 47 are inserted into the inner peripheral side of the ring-shaped support member 63 and fixed to the edge of the inner peripheral side of the support member 63 by welding or the like. . And the outer peripheral side of the supporting member 63 is being fixed to the wall surface in the chamber 41 by welding etc., as shown in FIG. The support member 63 is formed in a ring shape long in the left-right direction, and the outflow side end portions 46B and 47B of the two catalyst devices 46 and 47 are a left portion of one continuous space on the inner peripheral side of the support member 63 And are inserted in the right part respectively. The outer peripheral surface of the left half of the outflow side end 46B of the outflow side end 46B of the left catalytic device 46 is fixed to the inner peripheral face of the left side of the support member 63, and the outflow side end of the right catalytic device 47 In the case of 47B, the outer peripheral surface of the right half of the outflow side end portion 47B is fixed to the inner peripheral surface of the right portion of the support member 63. A gap is open between the middle portion on the inner peripheral side of the support member 63, that is, between the outflow side end portions 46B and 47B of the two catalyst devices 46 and 47. Thus, the gap G1 between the catalyst devices 46 and 47 is in communication with the space S in the rear of the outflow chamber R2.

  Further, the insertion holes 62 are formed at positions separated from each other in the partition portion 61 and apart from the wall surface in the chamber 41. Further, the inner circumferential surface of the support member 63 is separated from the wall surface in the chamber 41. Therefore, as the two catalyst devices 46 and 47 are supported by the insertion holes 62 of the partition 61 and the support member 63 as described above, the gap G1 is open between the two catalyst devices 46 and 47, and A gap G2 is also formed between the outer peripheral surface of the catalyst devices 46 and 47 and the wall surface in the chamber 41.

  A space S is formed at the rear of the outflow chamber R2 from the end face of the outflow side end portions 46B and 47B of the catalyst devices 46 and 47 to the vicinity of the rear wall surface in the chamber 41. There are no objects arranged to interrupt or divide the space S. A left joint pipe 42 is connected to the left joint pipe connection hole 57 formed on the left rear side of the outflow chamber R2, whereby the inside of the outflow chamber R2 communicates with the inside of the left joint pipe 42. . The right joint pipe 43 is connected to the right joint pipe connection hole 58 formed on the rear right side of the outflow chamber R2, whereby the inside of the outflow chamber R2 communicates with the inside of the right joint pipe 43.

  On the other hand, in the inflow chamber R1, a pair of collecting pipes 37, 38 are respectively connected to the inflow side connecting holes 56 respectively formed on the left and right portions of the front wall of the chamber 41. The reference numeral 38 opens into the inflow chamber R1. Further, in the inflow chamber R <b> 1, the end faces of the inflow side end portions 46 </ b> A and 47 </ b> A of the catalyst devices 46 and 47 face through the insertion holes 62 of the partition portion 61. Further, the end faces of the inflow side end portions 46A, 47A of the catalyst devices 46, 47 and the front face of the partition portion 61 are located in the same plane. Further, the ends (outflow side ends 37A, 38A) of the collecting pipes 37, 38 that are opened into the inflow chamber R1 are the inflow side end 46A of the catalyst device 46 facing in the inflow chamber R1. One of the end face and the end face of the inflow side end 47A of the catalyst device 47 is directed in the direction in which the end face is located. That is, as shown in FIG. 6, the outflow side end 37A of the left collective pipe 37 is gently bent to the right so that the end face of the inflow side end 46A of the left catalyst device 46 is located. . Further, the outflow end 38A of the right collective pipe 38 is gently bent to the left so as to face the end face of the inflow end 47A of the right catalyst device 47. In this embodiment, since the axis of the left collecting pipe 37 and the axis of the left catalyst device 46 are not largely deviated, the bending angle of the outflow side end 37A of the left collecting pipe 37 is small. Similarly, since the axis of the right collecting pipe 38 and the axis of the right catalyst device 47 are not largely deviated, the bending angle of the outflow end 38A of the right collecting pipe 38 is small.

Further, a hole for attaching the exhaust gas sensor 48 is formed in the right portion of the front upper wall plate 51 of the chamber 41, and the exhaust gas sensor 48 is attached to the hole. The exhaust gas sensor 48 detects the oxygen concentration of the exhaust gas that has flowed out of the two collecting pipes 37 and 38, respectively. The exhaust gas sensor 48 may be an O ₂ (oxygen) sensor or an A / F (air-fuel ratio) sensor. The detection result by the exhaust gas sensor 48 is used for fuel injection amount control and the like for causing fuel combustion in the engine 21 to be performed near the theoretical air fuel ratio and effectively exerting the purification effect of the exhaust by the catalyst devices 46 and 47.

  In the exhaust system 31 having such a configuration, the exhaust gases discharged from the respective exhaust ports of the engine 21 flow in the four exhaust pipes 33, 34, 35, 36, and then the two exhaust gases on the left side The exhaust gases flowing in the pipes 33, 34 merge with each other and flow in the left collecting pipe 37. Further, the exhaust gases flowing in the two right exhaust pipes 35, 36 merge with each other, and circulate in the right collecting pipe 38. Then, the exhaust flowing in the two collecting pipes 37, 38 flows into the inflow chamber R1 of the chamber 41, as shown in FIG. The exhaust gas flowing into the inflow chamber R1 subsequently flows into the catalytic devices 46, 47 from the respective inflow end portions 46A, 47A of the catalytic devices 46, 47, and is purified in the catalytic devices 46, 47. 47 from the outflow end 46B, 47B to the space S in the rear of the outflow chamber R2. Exhaust gas that has flowed out to the space S at the rear in the outflow chamber R2 is not only the space S at the rear in the outflow chamber R2, but also the gap G1 between the catalytic devices 46 and 47, and the respective catalytic devices 46 and 47 and the chamber 41. The gap G2 between the wall and the wall is circulated. Exhaust noise is reduced by the exhaust gas having flowed out of the catalyst devices 46 and 47 flowing through the space S, the gap G1 and the gap G2 in the rear of the outflow chamber R2. Further, the exhaust gas having flowed out of the catalyst devices 46 and 47 flows through the gap G1 and the gap G2, so that the exhaust gases hit the outer peripheral surface of the catalyst devices 46 and 47, and the heat of the exhaust gases causes the temperature of the catalysts 46 and 47 to rise. Do. Then, the exhaust gas in the outflow chamber R2 flows into the joint pipes 42, 43, sequentially circulates in the joint pipes 42, 43 and in the mufflers 44, 45, and is released to the atmosphere. Exhaust noise is further reduced by the exhaust gas flowing through the mufflers 44, 45.

  As described above, according to the exhaust device 31 of the embodiment of the present invention, the two catalyst devices 46 and 47 are arranged side by side with a gap G1 in the left-right direction. The exhaust gas after passing through can be circulated in the gap G1. Thereby, the reduction effect of the exhaust noise by the chamber 41 can be heightened. Further, since the gap G2 is formed between the outer peripheral surface of each of the catalyst devices 46 and 47 and the wall surface in the chamber 41, the exhaust after passing through the catalyst devices 46 and 47 is circulated in the gap G2. This can also enhance the effect of reducing the exhaust noise of the chamber 41.

  Further, the exhaust gas can be applied to the outer peripheral surface of the catalyst devices 46 and 47 by circulating the exhaust gas after passing through the respective catalyst devices 46 and 47 in the gap G1 and the gap G2. As a result, the heat of the exhaust can be used to achieve early activation of the catalyst devices 46, 47. Further, since the catalyst devices 46 and 47 are disposed in the common continuous outflow chamber R2, approximately the same amount of exhaust after passing through the catalyst devices 46 and 47 is applied to the outer peripheral surface of the catalyst devices 46 and 47. It can be applied simultaneously and the catalyst devices 46, 47 can be warmed evenly. This can prevent the activation of one of the catalyst devices 46 and 47 from being delayed. In addition, two catalyst devices 46 and 47 are disposed in the chamber 41, a gap G1 is formed between the two, and a gap G2 is formed around both of them. Can be

  Moreover, according to the exhaust system 31 of the embodiment of the present invention, by arranging the catalyst devices 46 and 47 on the front side of the middle position of the chamber 41, a large space S can be secured at the rear in the chamber 41. The space S can be used to enhance the exhaust noise reduction effect. In addition, since the catalyst devices 46 and 47 are disposed so that the inflow side end portions 46A and 47A are aligned in the front-rear direction, the space S can be enlarged, and the muffling performance of exhaust noise can be enhanced.

  Further, according to the exhaust system 31 of the embodiment of the present invention, the chamber 41 is divided by the partition portion 61 to form the inflow chamber R1 in the chamber 41, and the collecting pipes 37 and 38 are opened in the inflow chamber R1. And the end faces of the inflow side end portions 46A, 47A of the catalyst devices 46, 47 are made to face. Thereby, the exhaust gas sent to the chamber 41 through the collecting pipes 37, 38 can be uniformly flowed into the respective catalyst devices 46, 47.

  Further, according to the exhaust device 31 of the embodiment of the present invention, the end faces of the inflow side end portions 46A, 47A of the catalyst devices 46, 47 and the front surface of the partition portion 61 are positioned in the same plane. Thus, the exhaust can be smoothly introduced into the respective catalytic devices 46, 47, and the flow of the exhaust in the respective catalytic devices 46, 47 can be improved. Further, the exhaust gas can be uniformly flowed into the respective catalyst devices 46, 47, and the purification efficiency of the exhaust gas by the two catalyst devices 46, 47 can be enhanced. For example, it is possible to prevent the exhaust gas purification effect of the catalyst device from being sufficiently exhibited because the amount of exhaust gas flowing into one of the two catalyst devices 46 and 47 is small.

  Further, according to the exhaust system 31 of the embodiment of the present invention, the exhaust pipes sent through the collecting pipes 37, 38 are introduced into the inflow chamber R1 by opening the collecting pipes 37, 38 into the inflow chamber R1. It can be collected. Then, by detecting the oxygen concentration of the exhaust collected in the inflow chamber R1 with the exhaust gas sensor 48, the average oxygen concentration of the exhaust flowing into the respective catalyst devices 46, 47 can be detected. Therefore, the accuracy of oxygen concentration detection for performing fuel injection amount control (air-fuel ratio control) can be enhanced, and the accuracy of fuel injection amount control can be improved. Therefore, the exhaust gas purification effect of each of the catalyst devices 46 and 47 can be reliably exhibited. In addition, it is sufficient to provide a single exhaust gas sensor 48, ie, it is not necessary to provide a plurality of exhaust gas sensors for each of the exhaust pipes 33, 34, 35, 36 or for each of the collective pipes 37, 38. Cost can be reduced.

  Further, according to the exhaust system 31 of the embodiment of the present invention, the outflow side ends 37A, 38A of the collecting pipes 37, 38 are directed in the direction in which the inflow side ends 46A, 47A of the catalytic devices 46, 47 are located. Thus, the exhaust gas flowing into the inflow chamber R1 through the collecting pipes 37 and 38 can smoothly flow into the catalytic devices 46 and 47.

  Further, according to the exhaust system 31 of the embodiment of the present invention, the chamber 41 is disposed behind the oil pan 25, and the outflow end sides of the exhaust pipes 33, 34, 35, 36 and the collecting pipes 37, 38 are the oil pan 25. Since the piping is performed so as to sandwich the convex portion 25A of the above, it is possible to easily extend the lengths of the exhaust pipes 33, 34, 35, 36 and the respective collecting pipes 37, 38 in order to realize desired engine characteristics. it can.

  In the exhaust device 31 of the embodiment of the present invention, cylindrical catalyst devices 46 and 47 are employed. Cylindrical catalytic devices 46, 47 are available in the market for products of various sizes, and catalytic devices 46, 47 can be easily selected to match the size of the chamber 41. This increases the degree of freedom in the layout of the catalytic devices 46, 47. Therefore, the gap G1, the gap G2, and the space S can be easily secured in the chamber 41. Further, the cost of the exhaust system 31 can be reduced by selecting an inexpensive catalyst system provided in the market as the catalyst system 46, 47. In addition, since the catalyst devices 46 and 47 are the same product and equal in size to one another, the layout of the catalyst devices 46 and 47 is further facilitated, and the cost of the exhaust device 31 can be further reduced.

  In the embodiment described above, the two catalyst devices 46, 47 are arranged side by side with a gap in the left-right direction of the motorcycle 1, and the inflow side end portions 46A, 47A of the two catalyst devices 46, 47 face the front of the motorcycle 1. And in the front-rear direction of the motorcycle 1. As described above, the arrangement of the catalyst devices 46 and 47 is determined on the basis of the front-rear direction of the motorcycle 1 and the left-right direction of the motorcycle 1. However, the arrangement of the catalyst devices 46 and 47 The front-rear direction is not limited to the strict front-rear direction passing through the middle position of the motorcycle 1 in the vehicle width direction. The longitudinal direction of the motorcycle 1 serving as the reference of the arrangement of the catalyst devices 46, 47 is a direction inclined within a range of less than about -22.5 to less than about +22.5 degrees in the horizontal plane with respect to the above-mentioned strict longitudinal direction. including. Further, the lateral direction of the motorcycle 1 serving as the reference of the arrangement of the catalyst devices 46 and 47 is a direction orthogonal to the longitudinal direction of the motorcycle 1 serving as the reference of the arrangement of the catalyst devices 46 and 47 in the horizontal plane. For example, as shown in FIG. 8, the fore-and-aft direction B of the chamber 41 is inclined within a range of less than about -22.5 to less than about +22.5 degrees in a horizontal plane with respect to the rigid fore-aft direction A of the motorcycle 1. In this case, the arrangement of the catalyst devices 46 and 47 may be determined on the basis of the front-rear direction B.

  In the above-described embodiment, the catalyst devices 46 and 47 are arranged so that their axes are parallel to each other. However, the present invention is not limited thereto. For example, as shown in FIG. The inflow end of each of the devices 46 and 47 is directed to the front of the saddle-ride type vehicle, and the inflow end of each of the devices 46 and 47 is aligned in the front-rear direction of the saddle-ride type vehicle. It may be inclined at different angles in the horizontal plane.

  Further, in the above-described embodiment, cylindrical catalyst devices are used as the catalyst devices 46 and 47, but “cylindrical” as used herein also includes elliptic cylinders.

  In the embodiment described above, the case where the chamber 41 is disposed at the middle portion in the left-right direction of the motorcycle 1 is taken as an example, but the chamber 41 is arranged on the right or left side of the middle portion in the left-right direction of the motorcycle 1 It is also good.

  Further, the number of cylinders of the engine and the number of exhaust pipes may be two or more, and the number of collecting pipes may be three or more. Also, the number of joint pipes and the number of mufflers may be one. In addition, the collecting pipe may not be provided, and the exhaust pipe may be directly connected to the chamber. Further, the number of catalyst devices may be three or more.

  Furthermore, the present invention is applicable not only to motorcycles but also to other types of straddle-type vehicles such as motorcycles, buggies and the like.

  Further, the present invention can be suitably modified without departing from the scope of the invention or the spirit of the invention which can be read from the claims and the specification as a whole, and the exhaust system of a straddle-type vehicle with such modifications is also disclosed. It is included in the technical idea of the invention.

DESCRIPTION OF SYMBOLS 1 motorcycle 21 engine 25 oil pan 25A convex part 31 exhaust system 33, 34, 35, 36 exhaust pipe 37, 38 collective pipe 37A, 38A outflow side end 41 chamber 42, 43 joint pipe 44, 45 muffler 46, 47 catalyst Device 46A, 47A Inflow side end 46B, 47B Outflow side end 48 Exhaust gas sensor 61 Partitioning portion 62 Insertion hole 63 Support member R1 Inflow chamber R2 Outflow chamber G1, G2 Clearance S Space

Claims (9)

An exhaust pipe attached to an engine provided in a straddle-type vehicle,
A chamber connected downstream of the exhaust pipe;
A muffler connected to the chamber,
And a plurality of cylindrical catalyst devices provided in the chamber for purifying exhaust gas, respectively.
The plurality of catalyst devices are arranged side by side with a gap in the left-right direction of the straddle-type vehicle, and the respective inflow side ends face the front of the straddle-type vehicle, and the respective inflow side ends are An exhaust system for a straddle-type vehicle, wherein the exhaust system is aligned in the front-rear direction of the straddle-type vehicle.   The straddle-type vehicle according to claim 1, wherein the plurality of catalyst devices are supported in the chamber such that a gap is formed between an outer peripheral surface of each of the catalyst devices and a wall surface of the chamber. Exhaust system. The chamber includes a plate-like partition portion which divides the inside of the chamber in the front-rear direction of the straddle-type vehicle and forms an inflow chamber between the chamber and the front wall of the chamber.
The partition portion has a plurality of insertion holes into which the inflow side end portions of the plurality of catalyst devices are inserted,
3. The method according to claim 1, wherein the exhaust pipe is opened in the inflow chamber, and the inflow end sides of the plurality of catalyst devices face each other through the plurality of insertion holes. -Type vehicle exhaust system.   4. The exhaust system for a saddle-ride type vehicle according to claim 3, wherein the end face of the inflow side end of each of the plurality of catalyst devices and the front face of the partition are located in the same plane. And a plurality of exhaust pipes,
In the inflow chamber, the plurality of exhaust pipes or the plurality of exhaust pipes divided into a plurality of groups are combined into one for each of the plurality of groups, and a plurality of collecting pipes respectively connected are opened ,
5. The apparatus according to claim 3, wherein the inflow chamber is provided with a single exhaust gas sensor for detecting the oxygen concentration of the exhaust gas respectively flowing out from the plurality of exhaust pipes or the plurality of collecting pipes. Exhaust system for straddle-type vehicles. And a plurality of exhaust pipes,
In the inflow chamber, the plurality of exhaust pipes or the plurality of exhaust pipes divided into a plurality of groups are combined into one for each of the plurality of groups, and a plurality of collecting pipes respectively connected are opened ,
The end of the plurality of exhaust pipes or the plurality of collecting pipes open to the inflow chamber is directed to the direction in which the inflow side end of any one of the plurality of catalyst devices is located The exhaust system for a straddle-type vehicle according to claim 3 or 4, characterized in that: And a plurality of exhaust pipes,
In the inflow chamber, the plurality of exhaust pipes or the plurality of exhaust pipes divided into a plurality of groups are combined into one for each of the plurality of groups, and a plurality of collecting pipes respectively connected are opened ,
The chamber is located behind the oil pan,
The exhaust system for a straddle-type vehicle according to claim 3 or 4, wherein the plurality of exhaust pipes or the plurality of collective pipes are connected to sandwich a portion of the oil pan.   The straddle-type vehicle according to any one of claims 1 to 7, wherein the plurality of catalyst devices are disposed forward of an intermediate position of the chamber in the front-rear direction of the straddle-type vehicle. Exhaust system.   The exhaust system for a straddle-type vehicle according to any one of claims 1 to 8, wherein the plurality of catalyst devices have the same size.

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