JP6905637B2 - Exhaust muffler - Google Patents

Description

The present invention forms an exhaust gas flow path and has an exhaust pipe having a communication hole penetrating the pipe wall, a gas sensor attached to the exhaust pipe to detect gas in the exhaust pipe, and an exhaust pipe attached to the exhaust pipe. The present invention relates to an exhaust muffler provided with an outer cylinder that forms a space communicating with a communication hole around the exhaust pipe.

Patent Document 1 discloses an exhaust muffler provided with a resonator at the rear of the silencer. An opening for draining water is formed in the resonator chamber downward in the direction of gravity. For example, condensed water generated in the resonator chamber is discharged to the outside of the resonator chamber through a drainage opening.

Japanese Patent Application Laid-Open No. 2016-156326

A catalyst for purifying exhaust gas is placed upstream of the silencer. An O2 sensor that detects the action of the catalyst is arranged downstream of the catalyst. If a resonator is provided at the front of the silencer, outside air may enter the exhaust pipe through the drain hole of the resonator, which may affect the detection accuracy of the O2 sensor.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an exhaust muffler capable of ensuring the detection accuracy of a gas sensor even if a resonator is provided in front of the silencer.

According to the first aspect of the present invention, an exhaust pipe that forms a flow path for exhaust gas and has a communication hole that penetrates the pipe wall, and a gas sensor that is attached to the exhaust pipe and detects gas in the exhaust pipe. , Attached to the exhaust pipe to form a space around the exhaust pipe that communicates with the communication hole, at a position that does not overlap the communication hole in a bottom view, and on the upstream side of the communication hole in the exhaust gas flow direction. It is provided with an outer cylinder for arranging drain holes, and a plurality of the communication holes are provided in the longitudinal direction of the exhaust pipe. Apart from the communication holes, the outer cylinder has a front body formed in a conical shape that increases in diameter from the front end toward the downstream along the exhaust pipe, and the plurality of communication holes and the front body. Provides an exhaust muffler with a resonator.

According to the second side surface, in addition to the configuration of the first side surface, the gas sensor is arranged on the upstream side of the plurality of communication holes, and the distance between the gas sensor and the drain hole is the distance between the gas sensor and the drain hole. It is smaller than the distance to multiple communication holes.

According to the third side surface, in addition to the configuration of the second side surface, the gas sensor is arranged along the exhaust pipe on the upstream side of the outer cylinder.

According to the fourth side surface, in addition to any of the configurations of the first to third side surfaces, the front body is arranged behind the step on which the occupant's foot is placed when mounted on the saddle-riding vehicle. Will be done.

According to the fifth side surface, in addition to the configuration of the fourth side surface, the gas sensor is arranged in front of the step when mounted on a saddle-riding vehicle.

According to the sixth side surface, in addition to any of the configurations of the first to fifth side surfaces, a plurality of spaces are partitioned in the outer cylinder by one or more separators, and one of the spaces is a resonator chamber. be.

According to the seventh aspect, in addition to the configurations of the first to sixth aspects, the exhaust muffler further comprises a catalyst arranged in the exhaust pipe upstream of the gas sensor.

According to the eighth side surface, in addition to the configuration of the first to seventh side surfaces, the drain holes are provided at positions where the communication holes are plural and do not overlap the straight line connecting the center positions of the communication holes in the bottom view. Placed.

According to the first aspect, it is difficult for the outside air entering through the drain hole to flow into the exhaust pipe, and it is easy to secure the detection accuracy of the gas sensor. In addition, it is possible to reduce the number of members that prevent the inflow of outside air. In addition, the resonator room can be arranged without inviting an increase in the size of the outer cylinder. Moreover, since the communication hole is formed in the pipe wall of the exhaust pipe and the air in the resonator chamber is further taken in from the communication hole, it is possible to prevent backflow while exerting a sound deadening effect. In addition, since the drain hole 46 is arranged on the upstream side of the communication hole in the flow direction of the exhaust gas, the inflow of outside air is effective based on the labyrinth effect as compared with the case where the drain hole is arranged on the downstream side. Can be prevented.

According to the second aspect, since the drain hole is arranged on the upstream side of the communication hole in the flow direction of the exhaust gas, the inflow of outside air is based on the labyrinth effect as compared with the case where the drain hole is arranged on the downstream side. Can be effectively prevented.

According to the third aspect, the distance between the gas sensor and the communication hole can be secured, and the inflow of outside air can be effectively prevented.

According to the fourth aspect, the space for the passenger's feet can be easily secured without interfering with the outer cylinder that gradually expands in diameter.

According to the fifth aspect, the space of the gas sensor can be easily secured.

According to the sixth aspect, muffling can be effectively realized based on the arrangement of the resonator chamber.

According to the seventh aspect, since the gas sensor detects the exhaust gas downstream of the catalyst, the gas sensor can detect the deterioration of the catalyst.

According to the eighth side surface, since the drain hole is offset from the communication hole not only in the front-rear direction but also in the left-right direction, the inflow of outside air into the exhaust pipe can be more reliably prevented.

FIG. 1 is a side view schematically showing an overall configuration of a motorcycle, which is a specific example of a saddle-riding vehicle. FIG. 2 is an enlarged side view schematically showing the overall configuration of the exhaust muffler. FIG. 3 is an enlarged bottom view of an outer cylinder that schematically shows the configuration of the resonator chamber. FIG. 4 is an enlarged side view of an outer cylinder that schematically shows the configuration of the resonator chamber according to another embodiment. FIG. 5 is an enlarged side view of an outer cylinder corresponding to FIG. 3 and schematically showing the configuration of the resonator chamber according to another embodiment. FIG. 6 is an enlarged side view which corresponds to FIG. 2 and schematically shows the overall configuration of the exhaust muffler according to another embodiment.

11 ... Saddle-riding vehicle (motorcycle)
31 ... Exhaust pipe 32 ... Catalyst 33 ... Gas sensor (O2 sensor)
34 ... Outer cylinder 34a ... Front body 36 ... Step 37 ... First separator 38 ... Resonator chamber 39 ... Second separator 42 ... Third separator 45 ... Communication hole 46 ... Drain hole L1 ... (Sensor and drain hole) Distance L2 ... Distance (between the sensor and the communication hole)

Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. Here, the top, bottom, front, back, left, and right of the vehicle body are defined based on the line of sight of the occupant riding the motorcycle.

FIG. 1 schematically shows an overall configuration of a motorcycle according to an embodiment of the present invention. The motorcycle 11 includes a body frame 12. A front fork 14 is steerably supported by the head pipe 13 at the front end of the vehicle body frame 12. The front wheel WF is rotatably supported on the front fork 14 around the axle 15. A handlebar 16 is connected to the front fork 14 on the upper side of the head pipe 13. A swing arm 18 is swingably supported on the pivot frame 17 on the rear side of the vehicle body frame 12 around a support shaft 19 extending horizontally in the vehicle width direction. The rear wheel WR is rotatably supported around the axle 21 at the rear end of the swing arm 18.

The internal combustion engine 23 is mounted on the vehicle body frame 12 between the front wheel WF and the rear wheel WR. The internal combustion engine 23 produces power around the rotation axis Rx. The power of the internal combustion engine 23 is transmitted to the rear wheel WR via the power transmission device. In this description, the description of the same configuration as that of a known internal combustion engine may be omitted.

An exhaust muffler 24 is connected to the internal combustion engine 23 to discharge the exhaust gas of the internal combustion engine 23 to the rear of the vehicle body while performing a purification function and a muffling function. The exhaust muffler 24 is connected to the exhaust passage of the internal combustion engine 23 at the upstream end, passes under the internal combustion engine 23 and extends rearward, and exhausts in front of the rear wheel WR and below the swing arm 18. It is provided with a silencer unit 26 which is connected to the downstream end of the pipe unit 25 and has an exhaust port arranged at a position higher than the axle 21 on the side of the rear wheel WR. The silencer unit 26 functions to muffle the internal combustion engine 23. The exhaust gas from the internal combustion engine 23 is discharged rearward from the exhaust port of the silencer unit 26.

A fuel tank 27 for storing fuel is mounted on the vehicle body frame 12 above the internal combustion engine 23. A passenger seat 28 is mounted on the vehicle body frame 12 behind the fuel tank 27. Fuel is supplied from the fuel tank 27 to the fuel injection device (not shown) of the internal combustion engine 23. When driving the motorcycle 11, the occupant straddles the occupant seat 28.

As shown in FIG. 2, the exhaust pipe unit 25 includes an exhaust pipe 31 forming an exhaust gas flow path, a catalyst 32 incorporated in the exhaust pipe 31 in a descending region descending from the internal combustion engine 23, and a catalyst 32 for purifying the exhaust gas. It is provided with an O2 sensor 33 attached to the exhaust pipe 31 at the front end of the horizontal region extending in the horizontal direction continuously downstream from the descending region and detecting the oxygen concentration in the exhaust pipe 31. Deterioration of the catalyst 32 can be determined based on the oxygen concentration detected by the O2 sensor 33.

The exhaust pipe 31 is connected to an outer cylinder 34 that forms a space around the exhaust pipe 31 in the rear rising region that continuously extends downstream from the horizontal region. The outer cylinder 34 is connected to the front end 34a formed in a conical shape that expands in diameter from the front end toward the downstream along the exhaust pipe 31 and the rear end of the front body 34a, and is continuous from the space inside the front body 34a. It has a tubular body 34b that forms a space to be formed. Brackets 35a and 35b for connecting the outer cylinder 34 to the vehicle body frame 12 are fixed to the front body 34a and the cylinder 34b, respectively. For fixing, for example, welding is used. Since the front body 34a is formed of a single tube, the bracket 35a can be easily welded. As shown in FIG. 1, the front body 34a of the outer cylinder 34 is arranged behind the step 36 on which the occupant's foot is placed, and the O2 sensor 33 is arranged in front of the step 36. The O2 sensor 33 is arranged along the exhaust pipe 31 on the upstream side of the outer cylinder 34.

The front body 34a is fixed around the exhaust pipe 31 at the front end, and the first separator 37 is arranged in the front body 34a at a position away from the front end downstream. The first separator 37 partitions the resonator chamber 38 in the front body 34a. The exhaust pipe 31 penetrates the resonator chamber 38. A second separator 39 is arranged in the tubular body 34b at a position away from the front end of the tubular body 34b. The second separator 39 partitions the expansion chamber 41 from the first separator 37. The exhaust pipe 31 penetrates the first separator 37 and opens in the expansion chamber 41. Since the expansion chamber 41 is formed based on the double pipe, the number of component parts of the exhaust muffler 24 is reduced.

A third separator 42 located at the rear end of the cylinder 34b is incorporated in the cylinder 34b. The third separator 42 partitions the auxiliary expansion chamber 43 leading to the expansion chamber 41 from the second separator 39. A gap is formed between the second separator 39 and the cylinder body 34b of the outer cylinder 34 to communicate the auxiliary expansion chamber 43 with the expansion chamber 41. A discharge pipe 44 that connects the outside air to the expansion chamber 41 is supported in the second separator 39 and the third separator 42.

In the resonator chamber 38, a plurality of communication holes 45 penetrating the pipe wall are formed in the exhaust pipe 31. Here, three pairs of communication holes 45 are arranged, one pair at the top and one at the bottom. The communication hole 45 communicates with each other between the flow passage in the exhaust pipe 31 and the resonator chamber 38. Exhaust gas flows back and forth inside and outside the exhaust pipe 31 through the communication hole 45, so that resonance is generated and muffling is realized. The O2 sensor 33 is arranged on the upstream side of the communication hole 45.

In the front body 34a of the outer cylinder 34, a drain hole 46 is arranged at a position that does not overlap the communication hole 45 in the bottom view observed from a viewpoint located below infinity in the direction of gravity. The distance L1 between the O2 sensor 33 and the drain hole 46 is smaller than the distance L2 between the O2 sensor 33 and the communication hole 45. As shown in FIG. 3, the communication holes 45 are arranged at equal intervals along the straight line 47 connecting the center positions of the communication holes 45, and the drain holes 46 have an interval Dw equal to or greater than the interval Dc of the communication holes 45 in the bottom view. Separate from the most upstream communication hole 45.

Next, the operation of this embodiment will be described. In the exhaust muffler 24 according to the present embodiment, the outer cylinder 34 forms a resonator chamber 38 that communicates with the communication hole 45 of the exhaust pipe 31 around the exhaust pipe, and the drain hole 46 is located at a position that does not overlap the communication hole 45 in the bottom view. Be placed. Therefore, it is difficult for the outside air entering through the drain hole 46 to flow into the exhaust pipe 31, and it is easy to secure the detection accuracy of the O2 sensor 33. In addition, it is possible to reduce the number of members that prevent the inflow of outside air.

In the present embodiment, the O2 sensor 33 is arranged on the upstream side of the communication hole 45, and the distance L1 between the O2 sensor 33 and the drain hole 46 is smaller than the distance L2 between the O2 sensor 33 and the communication hole 45. In this way, since the drain hole 46 is arranged on the upstream side of the communication hole 45 in the flow direction of the exhaust gas, the inflow of outside air is effective based on the labyrinth effect as compared with the case where the drain hole 46 is arranged on the downstream side. Can be prevented.

The O2 sensor 33 is arranged along the exhaust pipe 31 on the upstream side of the outer cylinder 34. The distance L2 between the O2 sensor 33 and the communication hole 45 can be secured, and the inflow of outside air can be effectively prevented.

The outer cylinder 34 has a front body 34a formed in a conical shape whose diameter increases from the front end toward the downstream along the exhaust pipe 31, and the front body 34a has an exhaust muffler 24 mounted on the motorcycle 11. At this time, it is arranged behind step 36 on which the passenger's foot is placed. Since the outer cylinder 34 gradually expands in diameter, the space for the passenger's feet can be easily secured without interfering with the outer cylinder 34.

The O2 sensor 33 is arranged in front of step 36 when the exhaust muffler 24 is mounted on the motorcycle 11. The space for the O2 sensor 33 is easily secured.

A plurality of spaces are partitioned in the outer cylinder 34 by one or more separators 37, 39, 42, and one of the spaces is a resonator chamber 38. Mute is effectively realized based on the arrangement of the resonator chamber 38.

In the exhaust muffler 24 according to the present embodiment, the resonator chamber 38 is arranged in the front body 34a. According to such an arrangement, the resonator chamber 38 is arranged without inviting an increase in size of the outer cylinder 34.

The exhaust pipe 31 penetrates the resonator chamber 38, and the communication hole 45 opens into the resonator chamber 38. Since the communication hole 45 is formed in the pipe wall of the exhaust pipe 31 and the air in the resonator chamber 38 is further taken in from the communication hole 45, it is possible to prevent backflow while exhibiting a sound deadening effect.

The exhaust muffler 24 according to the present embodiment includes a catalyst 32 arranged in the exhaust pipe 31 upstream of the O2 sensor 33. Since the O2 sensor 33 detects the oxygen concentration downstream of the catalyst 32, the O2 sensor 33 can detect the deterioration of the catalyst 32.

As shown in FIG. 4, the lower communication hole 45 may be omitted from the above-described embodiment. The drain hole 46 is arranged at a position that does not overlap the straight line 47 connecting the center positions of the communication hole 45 in the bottom view, and the distance between the drain hole 46 and the communication hole 45 is further increased. The inflow is more reliably prevented. Further, as shown in FIG. 5, the communication hole 45 may be opened in the left-right direction orthogonal to the gravity direction and may be arranged at a position deviated from the drain hole 46 around the axis of the exhaust pipe 31. Since the drain hole 46 is arranged so as to be largely deviated from the virtual plane including the central position of the communication hole 45 in the circumferential direction of the exhaust pipe 31, the inflow of outside air into the exhaust pipe 31 is satisfactorily prevented. In addition, as shown in FIG. 6, the O2 sensor 33 may be attached to the exhaust pipe 31 immediately before the outer cylinder 34.

Claims (8)

An exhaust pipe (31) that forms a flow path for exhaust gas and has a communication hole (45) that penetrates the pipe wall.
A gas sensor (33) attached to the exhaust pipe (31) and detecting gas in the exhaust pipe (31),
Attached to the exhaust pipe (31), a space is formed around the exhaust pipe (31) to communicate with the communication hole (45), and the exhaust gas is located at a position not overlapping the communication hole (45) in a bottom view. An outer cylinder (34) in which a drain hole (46) is arranged on the upstream side of the communication hole (45) in the distribution direction, and
With
A plurality of the communication holes (45) are provided in the longitudinal direction of the exhaust pipe (31), and the drain holes (46) are at intervals (Dc) or more of the intervals (Dc) or more of the plurality of communication holes (45) in a bottom view. Dw) away from the most upstream communication hole (45),
The outer cylinder (34) has a front body (34a) formed in a conical shape that increases in diameter from the front end toward the downstream along the exhaust pipe (31), and has the plurality of communication holes (45). An exhaust muffler characterized in that a resonator is formed by the front body (34a). In the exhaust muffler according to claim 1, the gas sensor (33) is arranged on the upstream side of the plurality of communication holes (45), and the distance between the gas sensor (33) and the drain hole (46). (L1) is an exhaust muffler characterized in that it is smaller than the distance (L2) between the gas sensor (33) and the plurality of communication holes (45). The exhaust muffler according to claim 2, wherein the gas sensor (33) is arranged on the upstream side of the outer cylinder (34) along the exhaust pipe (31). In the exhaust muffler according to any one of claims 1 to 3, the front body (34a) is mounted on the saddle-riding vehicle (11) from the step (36) on which the passenger's foot is placed. Exhaust muffler characterized by being placed behind. The exhaust muffler according to claim 4, wherein the gas sensor (33) is arranged in front of the step (36) when mounted on the saddle-riding vehicle (11). .. In the exhaust muffler according to any one of claims 1 to 5, a plurality of spaces are partitioned in the outer cylinder (34) by one or more separators (37, 39, 42), and the space 1 One is an exhaust muffler characterized by being a resonator room (38). The exhaust muffler according to any one of claims 1 to 6, further comprising a catalyst (32) arranged in the exhaust pipe (31) upstream of the gas sensor (33). .. In the exhaust muffler according to any one of claims 1 to 6 and 9, the drain hole (46) does not overlap the straight line (47) connecting the center positions of the plurality of communication holes (45) in a bottom view. ) Is placed in the exhaust muffler.

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