WO2020021804A1

WO2020021804A1 - Exhaust gas sensor arrangement structure for saddle-type vehicle

Info

Publication number: WO2020021804A1
Application number: PCT/JP2019/017737
Authority: WO
Inventors: 勝己三浦; 健祐森; 千春河合; 正裕寺西
Original assignee: 本田技研工業株式会社
Priority date: 2018-07-27
Filing date: 2019-04-25
Publication date: 2020-01-30
Also published as: JPWO2020021804A1; DE112019003794T5; JP6928180B2

Abstract

The present invention improves the detection precision of an exhaust gas sensor in a saddle-type vehicle in which a power unit that includes an internal combustion engine is secured to a vehicle body frame, the exhaust gas sensor being disposed at a merging section of a plurality of exhaust pipes connected to the upstream side of a catalyst-containing pipe. This exhaust gas sensor arrangement structure for a saddle-type vehicle, the saddle-type vehicle 1 having a vehicle body frame 2a to which a power unit 3 is secured, includes exhaust pipes 7 comprising: a plurality of upstream-side exhaust pipes 71, upper ends of which are connected to an internal combustion engine 4 and guide out exhaust gas; an exhaust gas pipe merging section 72 where the upstream-side exhaust pipes merge; a catalyst-containing pipe 73 that is continuous with the exhaust gas merging section; and a downstream-side exhaust pipe 74, an upstream end 74a thereof being connected to the downstream end of the catalyst-containing pipe. The exhaust gas sensor arrangement structure for a saddle-type vehicle is configured so that an exhaust gas muffler 70 is connected to downstream ends 75b, 76b of the downstream-side exhaust pipe, wherein the exhaust gas pipe merging section has a curved section 72c, and an exhaust gas sensor 81 is disposed on an outer peripheral side 72ca of the curved section.

Description

Exhaust gas sensor arrangement structure for saddle type vehicle

The present invention relates to an arrangement structure of an exhaust gas sensor in a straddle-type vehicle.

A saddle-ride type vehicle in which an exhaust gas sensor is disposed inside a bent portion of a junction of a plurality of exhaust pipes connected to an upstream side of a catalyst-provided pipe is described in, for example, Patent Document 1 below. In the case of Patent Document 1 described below, since the exhaust gas flows outside the bent portion due to centrifugal force, the detection accuracy may be reduced.

Japanese Patent Application Laid-Open No. 2017-120026 (FIGS. 1 to 5)

SUMMARY OF THE INVENTION The present invention has been made in view of the related art, and in a saddle-ride type vehicle in which a power unit including an internal combustion engine is fixed to a body frame, a junction of a plurality of exhaust pipes connected to an upstream side of a catalyst internal pipe is provided. An object of the present invention is to provide an arrangement structure of an exhaust gas sensor capable of improving the detection accuracy of an exhaust gas sensor provided in a vehicle.

In order to solve the above problems, according to the present invention,
A power unit including an internal combustion engine is fixed to a body frame of a saddle type vehicle,
A plurality of upstream exhaust pipes each having an upstream end connected to the internal combustion engine to discharge exhaust gas; an exhaust pipe assembly that joins the upstream exhaust pipe; and a catalyst installed continuously with the exhaust pipe assembly. Exhaust of a straddle-type vehicle having an exhaust pipe having a pipe and a downstream exhaust pipe connected to an upstream end at a downstream end of the catalyst internal pipe, and an exhaust muffler connected to a downstream end of the downstream exhaust pipe. In the gas sensor arrangement structure,
The exhaust pipe assembly has a bent portion, and an exhaust gas sensor is disposed on an outer peripheral side of the bent portion.

According to the exhaust gas sensor arrangement structure of the straddle-type vehicle of the present invention,
At the bent portion of the exhaust pipe assembly, the flow rate of the exhaust gas is increased by the centrifugal force on the outer peripheral side, and the mixing of the exhaust gas is improved as the exhaust pipe assembly, thereby improving the detection accuracy of the exhaust gas sensor.

According to a preferred embodiment of the present invention,
The bending portion bends in the vehicle horizontal direction.
Therefore, when the bent portion is bent up and down, the exhaust gas sensor provided on the outer peripheral side of the bent portion projects upward and downward, causing a problem of vertical clearance, but the bent portion is bent in the vehicle horizontal direction. Therefore, the exhaust gas sensor attached to the outer peripheral side is located on the side, and upward and downward projection can be avoided.

According to a preferred embodiment of the present invention,
The downstream end side of the upstream side exhaust pipe is constituted by a plurality of unit exhaust pipes, and the downstream ends of the plurality of unit exhaust pipes are assembled and inserted into the exhaust pipe collecting part, and the downstream end side of the exhaust gas sensor is closer to the exhaust gas sensor. The insertion length of the unit exhaust pipe is shorter than the insertion length of the remote unit exhaust pipe.
Therefore, the flow of the exhaust gas introduced from the unit exhaust pipe farther from the exhaust gas sensor to the exhaust pipe assembly is not obstructed by the unit exhaust pipe closer to the exhaust gas sensor, so that the introduction of the exhaust gas from each unit exhaust pipe is not hindered. .

According to a preferred embodiment of the present invention,
A catalyst is provided in the catalyst internal pipe connected to the downstream side of the exhaust pipe assembly, and an upstream end face of the catalyst faces obliquely from a direction perpendicular to the insertion direction of the unit exhaust pipe. , Characterized by being inclined toward the outer peripheral side of the bent portion.
Therefore, the exhaust gas reflected on the upstream end face of the catalyst flows toward the outer peripheral side of the bent portion, and the mixing of the exhaust gas is promoted, and the detection accuracy of the exhaust gas sensor is improved.

According to a preferred embodiment of the present invention,
The bent portion is disposed on a side portion of the oil pan.
Therefore, the exhaust gas sensor is protected by the oil pan.

According to a preferred embodiment of the present invention,
In the exhaust pipe assembly, an outer peripheral side of the bent portion is arranged on a side opposite to the oil pan in a vehicle width direction.
Therefore, removal and maintenance of the exhaust gas sensor attached to the outer peripheral side of the bent portion are facilitated.

According to a preferred embodiment of the present invention,
An output sprocket is provided on an output shaft protruding from the crankcase of the power unit, and a harness support sprocket cover that covers the output sprocket is provided.The harness support sprocket cover includes a coupler provided in the harness of the exhaust gas sensor. The coupler stay to be fixed is integrally formed.
By using the existing sprocket cover as a harness support sprocket cover integrally provided with a coupler stay, it is possible to reduce the number of components for fixing the coupler of the harness.

FIG. 2 is a left side view of the motorcycle according to the embodiment. FIG. 2 is a left side view showing a lower left side of a power unit of the motorcycle in FIG. 1 and an exhaust pipe. FIG. 3 is a bottom view of the motorcycle according to the embodiment with an oil pan removed from a crankcase to a rear wheel, as viewed from arrows III-III in FIG. 2. FIG. 4 is an enlarged plan view of the exhaust pipe assembly and the front and rear thereof, as viewed from arrows IV-IV in FIG. 2. FIG. 5 is a left side view showing a lower left side and an exhaust pipe of a lower portion of a power unit of a motorcycle according to a modification of the present embodiment, similarly to FIG. 2. FIG. 6 is a left side view showing the harness supporting sprocket cover shown in FIG. 5. FIG. 6 is a left side view showing a lower left side and an exhaust pipe of a power unit of a motorcycle provided with another form of exhaust pipe using the harness support sprocket cover of FIG. 5. FIG. 8 is a top view of the exhaust pipe of the motorcycle of FIG. 7, as viewed in the direction of arrows XIII-VIII in FIG. 7 is a perspective view of a harness support sprocket cover and the like similar to FIG. 6 attached to a crankcase in the motorcycle having the exhaust pipe of another form of FIG. is there.

An exhaust gas sensor arrangement structure of a straddle-type vehicle according to an embodiment of the present invention and a modification thereof will be described with reference to FIGS.
The directions such as front, rear, left, right, up, and down in the description and the claims of the present specification are in accordance with the directions of the saddle-ride type vehicle equipped with the exhaust pipe of the saddle-ride type vehicle according to the present embodiment. In this embodiment, the straddle-type vehicle is the motorcycle 1.
In the drawings, the arrow FR indicates the front of the vehicle, LH indicates the left side of the vehicle, RH indicates the right side of the vehicle, and UP indicates the upper side of the vehicle.
7 to 9, a description will be given of a motorcycle 1 'having a different form of exhaust pipe 7' provided with a harness support sprocket cover 60 similar to the modification of the above embodiment.
FIG. 9 is also referred to in a modification of the present embodiment.

FIG. 1 is a left side view of the motorcycle 1 of the present embodiment.
As shown in FIG. 1, the body frame 2 of the motorcycle 1 is divided into right and left parts from a head pipe 20 so that

main frames

21, 21 extend rearward, and rear

center frame parts

21a, 21a are bent downward. ing.

Down frames

22, 22 extend obliquely downward and rearward from the head pipe 20.
A seat rail 23 extends obliquely upward and rearward from a position closer to the front than the upper bent portion of the center frame portions 21a of the

main frames

21, 21.

The front wheel 12 is pivotally supported at the lower end of a front fork 11 slidably supported by a head pipe 20, and a handle 13 is connected to the front fork 11 via a steering shaft (not shown) extending upward.

A rear fork 14 whose front end is pivotally supported by a pivot shaft 24 extends rearward, and a rear wheel 15 that is pivotally supported at its rear end is provided on the center frame portion 21a so as to be vertically swingable.
A rear suspension link 19 is provided between a lower edge of the rear fork 14 and a lower end of the center frame portion 21a, and a rear suspension 16 is provided between a part of the rear suspension link 19 and an upper portion of the center frame portion 21a. It is interposed.

The motorcycle 1 has a power unit 3 including an internal combustion engine 4 fixedly mounted on a vehicle body frame 2. The power unit 3 is configured such that the transmission 5 is integrally accommodated in a rear portion inside a crankcase 40 of the internal combustion engine 4, and is suspended by a down frame 22 on the front side of the main frame 21 and the main frame 21. The internal combustion engine 4 is a water-cooled in-line four-cylinder four-stroke cycle internal combustion engine in which four cylinders are arranged in the vehicle width direction, and its crankshaft 41 is directed in the vehicle width direction (left-right direction).

A counter shaft 52 of the transmission 5, which is an output shaft 52 of the power unit 3, protrudes leftward through a left bearing wall of the crankcase 40, and is provided with an output sprocket 53 fitted to a left end thereof. I have.
A drive chain 55 is wound around the output sprocket 53 and a driven sprocket 54 fitted on the rear axle 15a of the rear wheel 15, and the output of the power unit 3 is transmitted to the rear wheel 15 via the drive chain 55 and automatically transmitted. The motorcycle 1 runs.
The output sprocket 53 is covered with a sprocket cover 56 to improve aesthetics and safety.
Above the power unit 3, a fuel tank 17 is mounted on the main frame 21, and a seat 18 is provided behind the fuel tank 17 and supported by a seat rail 23.

The cylinder block 42 and the cylinder head 43 are fastened on a crankcase 40 that rotatably supports the crankshaft 41 with the cylinder axis C slightly inclined forward, so that the cylinder block 42 and the cylinder head 43 are sequentially overlapped. A cylinder head cover 44 is put on the cylinder head 43.
An intake pipe 47 extends upward from a rear portion of the cylinder head 43 that is inclined forward of the internal combustion engine 4 and is connected to an air cleaner 49 via a throttle body (not shown).
The exhaust pipe 7 extends downward from the front of the cylinder head 43, passes under the crankcase, and extends diagonally upward on the right side of the rear wheel 15 to be connected to the exhaust muffler 70.
An ECU (engine control unit) 100 that controls the internal combustion engine 4 and the like is installed near the air cleaner 49.
An oil pan 46 is attached to a lower portion of the crankcase 40.

FIG. 2 shows the left side surface of the lower part of the power unit 3 of the motorcycle 1 and the exhaust pipe 7.
Note that FIG. 2 shows the output sprocket 53 exposed with the sprocket cover 56 shown in FIG. 1 removed.
The exhaust pipe 7 according to the present embodiment includes four primary exhaust pipes 71a that are connected to the four exhaust ports on the front side surface of the cylinder head 43 at their upstream ends to lead the exhaust gas, and the four primary exhaust pipes. An upstream exhaust pipe 71 composed of a unit exhaust pipe 71b that is joined by two at the downstream side of the exhaust pipe 71a, one exhaust pipe collecting section 72 commonly connected to the two unit exhaust pipes 71b, and an exhaust pipe collecting section A catalyst-incorporated pipe 73, which is provided in the direction of extension of the downstream end 72b of the internal combustion engine 72 and is arranged rearward below the internal combustion engine 4, has an upstream end connected to the catalyst-incorporated pipe 73, and A downstream exhaust pipe 74 extending obliquely upward and having a downstream end connected to the exhaust muffler 70 is provided.
Note that, unlike the present embodiment, there are various forms such as an internal combustion engine having two cylinders, two primary exhaust pipes 71a being directly used as two unit exhaust pipes 71b to constitute the upstream exhaust pipe 71, and the like. Included in the present invention.

FIG. 3 is a bottom view of the motorcycle 1 of the present embodiment, with the oil pan 46 extending from the crankcase 40 to the rear wheel 15 removed, as viewed from arrows III-III in FIG.
As shown in FIG. 3, the upstream exhaust pipe 71 is configured such that four primary exhaust pipes 71 a are provided on the downstream side thereof in a plurality, and in the embodiment, two unit exhaust pipes 71 b, and the downstream end 71 ba, 71bb are assembled and inserted into one exhaust pipe collecting section 72.

The exhaust pipe collecting section 72 is located substantially near the center in the vehicle width direction of the vehicle, that is, near the vehicle left / right center line X in order to join the upstream exhaust pipe 71, but distributes exhaust gas to the right side of the rear wheel 15. In order to guide the exhaust muffler 70 provided, the catalyst internal pipe 73 and the downstream exhaust pipe 74 connected to the downstream side of the exhaust pipe collecting section 72 are arranged obliquely from the vehicle center side to the vehicle right side.
Therefore, the exhaust pipe assembly 72 has a bent portion 72c that is bent rightward from front to rear in the vehicle horizontal direction.

The downstream side exhaust pipe 74 has a main pipe part 75 and a branch pipe part 76 on the downstream side of the upstream end 74a, and has a branch part 77 from which the branch pipe part 76 branches off from the main pipe part 75.
In the branch part 77, the branch pipe part 76 overlaps the vehicle center side of the main pipe part 75 in a side view as shown in FIG. 2, and as shown in FIG. 4, both the main pipe part 75 and the branch pipe part 76 are located downstream of the main pipe part 75. The ends 75b and 76b are connected to the upstream end 70a of the exhaust muffler 70 disposed on the right side of the rear wheel 15.

In the motorcycle 1 of the present embodiment, the exhaust gas sensor 81 that detects the oxygen concentration and the like in the exhaust gas before passing through the catalyst 73 a in the catalyst internal pipe 73 is used for exhaust gas purification. It is provided on the bent portion 72c.
The exhaust gas sensor 81 is a LAF sensor or an O ₂ sensor. In the present embodiment, a downstream exhaust gas sensor 85 for detecting exhaust gas after passing through the catalyst 73 a is also provided downstream of the catalyst internal pipe 73. I have.

As shown in FIG. 2, the harness 82 of the signal line connected to the exhaust gas sensor 81 is directed toward the ECU 100 (see FIG. 1) between the generator cover 30 on the left end side of the crankshaft 41 and the output sprocket 53. , And are fixed in some places by support members 90.
Also, the harness 26 from the stand switch 25a for detecting the state of the side stand 25 being put in and out is similarly arranged upward alongside the harness 82 of the exhaust gas sensor 81, and is fixed by the support member 90 in some places.

The exhaust gas sensor 81 is disposed on the outer peripheral side 72ca of the bent portion 72c of the exhaust pipe collecting portion 72. At the outer peripheral side 72ca of the bent portion 72c, the flow rate of the exhaust gas increases due to centrifugal force. Since the mixing of the exhaust gas is improved, the detection accuracy of the exhaust gas by the exhaust gas sensor 81 is improved.

Further, the bent portion 72 is bent in the vehicle horizontal direction, and when the bent portion is bent in the vertical direction as in the above-described conventional technology, the exhaust gas sensor provided on the outer peripheral side of the bent portion projects upward and downward. Thus, the problem of upper and lower clearance occurs, but in the present embodiment, since the bent portion 72c is bent in the vehicle horizontal direction, the exhaust gas sensor 81 attached to the outer peripheral side 72ca is positioned so as to protrude laterally, An upward and downward protrusion is avoided.

FIG. 4 is an enlarged plan view of the exhaust pipe collecting portion 72 and its front and rear portions as viewed from arrows IV-IV in FIG.
As shown in FIG. 4, the downstream end of the upstream exhaust pipe 71 is constituted by a plurality of unit exhaust pipes 71 b, and the exhaust pipe collecting section 72 includes a plurality of unit exhaust pipes 71 b, and in this embodiment, two unit exhaust pipes 71 b The downstream ends 71ba, 71bb of the exhaust pipe 71b are assembled and inserted.
An exhaust gas sensor 81 is attached to the outer peripheral side 72ca of the bent portion 72c of the exhaust pipe collecting section 72. The insertion length La of the unit exhaust pipe 71b near the exhaust gas sensor 81 is the same as the unit exhaust pipe 71b on the far side. Is set shorter than the insertion length Lb.
Therefore, the flow of the exhaust gas introduced from the downstream end 71bb of the unit exhaust pipe 71b far from the exhaust gas sensor 81 to the exhaust pipe collecting section 72 is not obstructed by the downstream end 71ba of the close unit exhaust pipe 71b. The introduction of exhaust gas from the unit exhaust pipe 71b is not hindered.

As shown in FIG. 4, a catalyst 73a is provided in a catalyst internal pipe 73 connected to the downstream side of the exhaust pipe collecting section 72, and an upstream end face 73aa of the catalyst 73a is a unit. The exhaust pipe 71b faces obliquely perpendicular to the insertion direction A of the exhaust pipe 71b, and inclines toward the outer peripheral side 72ca of the bent portion 72c.
Therefore, the exhaust gas reflected on the upstream end face 73aa of the catalyst 73a flows toward the outer peripheral side 72ca of the bent portion 72c, and the mixing of the exhaust gas is promoted, and the detection accuracy of the exhaust gas sensor 81 is improved.

As shown in FIGS. 1 and 2, in the present embodiment, the exhaust pipe collecting section 72 and the catalyst internal pipe 73 on the downstream side of the upstream exhaust pipe 71 are disposed rearward around the lower part of the crankcase 40. However, the bent portion 72c of the exhaust pipe collecting portion 72 is disposed on the side of the oil pan 46.
Therefore, the exhaust gas sensor 81 is protected by the oil pan 46.

Further, in the exhaust pipe collecting section 72, the outer peripheral side 72ca of the bent portion 72c is disposed on the opposite side to the oil pan 46 in the vehicle width direction, so that the removal of the exhaust gas sensor 81 attached to the outer peripheral side 72ca, Maintenance is easy.

FIG. 5 is a left side view showing the lower left side of the power unit 3 of the motorcycle 1 and the exhaust pipe 7 in a modification of the present embodiment, similarly to FIG.
In this modification, a harness support sprocket cover 60 that supports a harness 82 connected to an exhaust gas sensor 81 is provided so as to cover an output sprocket 53 provided on an output shaft 52 protruding from a crankcase (40). .
The harness support sprocket cover 60 covers the drive chain 55 wound around the output sprocket 53 to the front of the center frame portion 21a behind the generator cover 30 (right side in the figure) located in front, to provide aesthetics and safety. However, a structure for supporting the harness 82 and the like is further provided.

FIG. 6 is a left side view showing the harness support sprocket cover 60 shown in FIG.
The harness support sprocket cover 60 of the present modified example is formed of a resin-based member, and as shown, a circular central portion 61 covering the left side of the output sprocket 53, and a left side of the drive chain 55. An upper portion 62, a lower portion 63, and an intermediate portion 64 connecting the upper portion 62 and the lower portion 63 are formed, and further provided with a coupler stay 65 extending downward integrally from the lower portion 63. In the present modification, an upper plate-like portion 65a and a lower plate-like portion 65b are formed on the coupler stay 65 so as to extend obliquely forward and upward.
In the front half of the central portion 61, a rising portion 66a extending in the vertical direction and protruding toward the left (front side in the drawing), and a front portion (left side in the drawing) from the left top (the front end in the drawing) of the rising portion 66a. ) Is integrally formed with a harness guide 66 having a hook 66b that bends toward the upper side.
The material of the harness support sprocket cover 60 is appropriately selected, and is not limited to a resin-based member.

FIG. 9 is a perspective view of a similar harness support sprocket cover 60 and the like attached to a crankcase 40 of a motorcycle 1 ′ having a different form of exhaust pipe 7 ′, which will be described later. The harness support sprocket cover 60 of the modified example also has a rising part in which a harness guide part 66 formed in the front half of the central part 61 extends in the vertical direction and protrudes leftward, as shown in FIG. It is attached to the crankcase 40 with a hook 66b which is bent forward from the left top of the rising portion 66a.
The same rising shape of the harness guide portion 66 of the harness support sprocket cover 60 of this modification is referred to in FIG.

In the coupler stay 65, the coupler 82a of the harness 82 connected to the exhaust gas sensor 81 is attached to the upper plate-shaped portion 65a to support the harness 82, and the lower plate-shaped portion 65b is connected to the stand switch 25a of the side stand 25. The coupler 26a of the harness 26 is mounted, and the harness 26 is supported.

Although the harness 82 and the harness 26 extending from the coupler 82a and the coupler 26a are arranged side by side (see FIG. 5), the rising portion 66a and the generator cover are formed by the harness guide 66 of the harness support sprocket cover 60. In the gap portion 45 between the harness guide portion 66 and the other wires and tubes, the hook portion 66b of the harness guide portion 66 prevents the harness 82, the harness 26, and the like from deviating to the left (front side in the figure). ing.
In this modification, the existing sprocket cover 56 is made a harness support sprocket cover 60 provided by integrally forming the coupler stay 65 so that the

couplers

82a and 26a of the

harnesses

82 and 26 are fixed. It is possible to reduce the number of parts.

FIG. 7 shows another form of exhaust pipe 7 'using the harness support sprocket cover 60 shown in FIG.
FIG. 5 is a left side view showing a lower left side of a power unit 3 and an exhaust pipe 7 ′ of a motorcycle 1 ′ having the same.
The motorcycle 1 'of another embodiment differs from the motorcycle 1 of the embodiment and its modifications in the arrangement of the exhaust gas sensor of the exhaust pipe 7'.
Also, in the motorcycle 1 'having the exhaust pipe 7' of another form, the output sprocket 53 provided on the output shaft 52 protruding from the crankcase 40 is covered similarly to the modification of the above-described embodiment. A harness support sprocket cover 60 is provided.

FIG. 8 is a top view of the exhaust pipe 7 ′ taken substantially along the line VIII-VIII in FIG.
The exhaust pipe 7 'of the motorcycle 1' of another embodiment is for a four-cylinder engine as in the embodiment, and the upstream end is connected to four exhaust ports on the front side surface of the cylinder head 43 (see FIG. 1), four upstream exhaust pipes 71a for deriving exhaust gas, and two unit exhaust pipes 71b downstream of the four primary exhaust pipes 71a, and two upstream exhaust pipes 71b. One exhaust pipe collecting part 72 commonly connected to the unit exhaust pipe 71b and a downstream end 72b of the exhaust pipe collecting part 72 are connected to each other in an extending direction and disposed rearward below the internal combustion engine 4. And a downstream exhaust pipe 74 whose upstream end is connected to the catalyst internal pipe 73, extends obliquely upward on the right side of the vehicle body, and whose downstream end is connected to the exhaust muffler 70. (See FIG. 1).
As shown in FIG. 8, the upstream exhaust pipe 71 has a plurality of unit exhaust pipes 71b on the downstream side of the four primary exhaust pipes 71a, and two unit exhaust pipes 71b in the embodiment, and has downstream ends 71ba, 71bb are assembled and inserted into one exhaust pipe collecting section 72.

The exhaust gas sensor does not include the downstream exhaust gas sensor 85 in the above-described embodiment on the downstream side of the catalyst internal pipe 73.
On the other hand, on the upstream side of the catalyst internal pipe 73, an exhaust gas sensor 81 is provided at one place on the outer peripheral side 72ca (see FIG. 2) of the bent portion 72c of the exhaust pipe collecting section 72 as in the above-described embodiment. Instead, as shown in FIG. 8,

exhaust gas sensors

86 and 88 are provided for each of the unit exhaust pipes 71b where the downstream side of the primary exhaust pipe 71a merges two by two.
That is, as shown in FIGS. 7 and 8, the first exhaust gas sensor mounting hole 86a is provided at the junction 71ab from the primary exhaust pipe 71a to the outer unit exhaust pipe 71b, and the first exhaust gas sensor 86 is mounted. ing.
At a junction 71ab from the primary exhaust pipe 71a to the inner unit exhaust pipe 71b, a second exhaust gas sensor mounting hole 88a is provided, and the second exhaust gas sensor 88 is mounted.

FIG. 9 is a perspective view of a harness supporting sprocket cover 60 and the like similar to that of the modified example of the embodiment, which is attached to the crankcase 40 of the motorcycle 1 'having the exhaust pipe 7' of another form, from the lower left rear side. It is a perspective view.
The harness support sprocket cover 60 covers an output sprocket 53 provided on an output shaft 52 protruding from the crankcase 40, similarly to the modification of the above-described embodiment.

As shown in FIG. 9, the harness 89 of the signal line from the inner second exhaust gas sensor 88 is connected to the rising portion 66a of the harness guide 66 of the harness support sprocket cover 60 and the generator cover via a coupler 89a. It is routed upward to the ECU 100 (see FIG. 1) with a gap 45 between itself and 30.
The harness 87 of the signal line from the outer first exhaust gas sensor 86 is connected to and supported by the coupler 87a mounted on the upper plate-like portion 65a of the coupler stay 65 of the harness support sprocket cover 60, and has exited the coupler 87a. The harness 87 is routed toward the ECU 100 (see FIG. 1) with the gap 45 upward while turning over.

The coupler 26a of the harness 26 from the stand switch 25a of the side stand 25 is attached to the lower plate-like portion 65b of the coupler stay 65, and the harness 26 is supported.
The harness 26 exiting the coupler 26a is routed together with the harness 87 to the ECU 100 (see FIG. 1) with the gap 45 upward.

In the gap 45, a harness 89 from the second exhaust gas sensor 88, a harness 87 from the first exhaust gas sensor 86, and a harness 26 from the stand switch 25a, together with other wiring and tubes, are connected to the harness guide portion of the harness support sprocket cover 60. 66, it is held between the rising portion 66a and the generator cover 30, and the hook portion 66b of the harness guide portion 66 prevents the harness 87, the harness 26, and the like from deviating to the left (front side in the figure). I have.
Also in the motorcycle 1 'of the above-described another embodiment, the existing sprocket cover 56 is formed as the harness support sprocket cover 60 provided integrally with the coupler stay 65, so that the couplers of the

harnesses

87 and 26 are provided. The number of parts for fixing the

parts

87a and 26a can be reduced.

Further, in the exhaust pipe 7 'of the motorcycle 1' of the above-described another embodiment, instead of providing the downstream exhaust gas sensor 85 in the above-described embodiment, a unit exhaust pipe 71b is provided upstream of the catalyst internal pipe 73. Each time, the

exhaust gas sensors

86 and 87 are provided at the junction 71ab from the primary exhaust pipe 71a to the unit exhaust pipe 71b. Therefore, even when it is difficult to install the exhaust gas sensor 81 at the position specified in the above embodiment, high-precision exhaust It is possible to obtain gas detection accuracy.

As mentioned above, although one Embodiment of this invention and its modification, and another form were described, this invention is not limited to the above-mentioned embodiment and its modification, and various other things are carried out in the range of the summary of this invention. Changes are possible. For example, the power unit and the internal combustion engine of the present invention are not limited to motorcycles but may be widely applied to other types of straddle-type vehicles.
For convenience of explanation, the left and right arrangement of the apparatus has been described in accordance with the illustrated embodiment, but is not limited thereto, and the left and right arrangement may be reversed.

1, 1 'motorcycle, 2 body frame, 3 power unit, 4 internal combustion engine, 7, 7' exhaust pipe, 14 rear fork, 15 rear wheel, 21 main frame, 21a center frame , 25 ... side stand, 25a ... side stand switch, 26 ... harness, 26a ... coupler, 30 ... generator cover, 40 ... crankcase, 41 ... crankshaft, 42 ... cylinder block, 43 ... cylinder head, 45 ... gap, 46 ... oil pan, 52 ... output shaft (counter shaft), 53 ... output sprocket, 54 ... driven sprocket, 55 ... drive chain, 56 ... sprocket cover, 60 ... harness support sprocket cover, 65 ... coupler stay, 65a ... upper plate Shape, 65b: lower plate-shaped portion, 66: harness guide portion, 66a: rising portion, 66b: hook portion, 70: exhaust muffler, 70a: upstream end, 71: upstream exhaust pipe, 71a ... Primary exhaust pipe, 71b: Unit exhaust pipe, 72: Exhaust pipe assembly, 72b: Downstream end, 72c: Bend, 72ca: Outer side, 73: Internal catalyst pipe, 73a: Catalyst, 73aa: Upstream end face, 74 ... downstream exhaust pipe, 74a ... upstream end, 75 ... main pipe section, 75b ... downstream end, 76 ... branch pipe section, 76b ... downstream end, 77 ... branch section, 81 ... exhaust gas sensor, 82 ... harness, 82a ... coupler, 86 ... first exhaust gas sensor, 86a ... first exhaust gas sensor mounting hole, 87 ... harness, 87a ... coupler, 88 ... second exhaust gas sensor, 88a ... second exhaust gas sensor mounting hole, 89 ... harness, 89a ... coupler, 100 ... ECU (engine control unit), C: cylinder axis, X: left-right center line of vehicle, A: insertion direction of unit exhaust pipe 71b

Claims

A power unit (3) including an internal combustion engine (4) is fixed to a body frame (2) of a saddle-ride type vehicle (1),
A plurality of upstream exhaust pipes (71) each having an upstream end connected to the internal combustion engine (4) and leading out exhaust gas; an exhaust pipe assembly (72) joining the upstream exhaust pipe (71); An internal catalyst pipe (73) connected to the exhaust pipe assembly (72), and a downstream exhaust pipe (74) connected to the downstream end of the internal catalyst pipe (73) at the upstream end (74a). An exhaust gas sensor arrangement of a straddle-type vehicle having an exhaust pipe (7) having a downstream exhaust pipe (74) and an exhaust muffler (70) connected to a downstream end (75b, 76b) of the downstream exhaust pipe (74).
The exhaust pipe assembly (72) has a bent portion (72c), and an exhaust gas sensor (81) is arranged on an outer peripheral side (72ca) of the bent portion (72c). Exhaust gas sensor arrangement structure.
The exhaust gas sensor arrangement structure for a straddle-type vehicle according to claim 1, wherein the bent portion (72c) is bent in a vehicle horizontal direction.
The downstream end side of the upstream side exhaust pipe (71) is constituted by a plurality of unit exhaust pipes (71b), and the exhaust pipe assembly (72) has downstream ends (71ba, 71b) of the plurality of unit exhaust pipes (71b). 71bb) are assembled and inserted, and the insertion length (La) of the unit exhaust pipe (71b) on the side closer to the exhaust gas sensor (81) is the insertion length (La) of the unit exhaust pipe (71b) on the far side. The exhaust gas sensor arrangement structure for a saddle-ride type vehicle according to claim 1, wherein the length is shorter than Lb).
A catalyst (73a) is provided in the catalyst internal pipe (73) connected to the downstream side of the exhaust pipe assembly (72), and the upstream end face (73aa) of the catalyst (73a) is The saddle according to claim 3, characterized in that the unit exhaust pipe (71b) faces obliquely with respect to the insertion direction of the unit exhaust pipe (71b) and inclines toward an outer peripheral side (72ca) of the bent portion (72c). Exhaust gas sensor arrangement structure for ride-on vehicles.
The arrangement according to claim 1, wherein the bent portion (72c) is disposed on a side portion of the oil pan (46).
6. The exhaust pipe assembly (72), wherein an outer peripheral side (72ca) of the bent portion (72c) is arranged on a side opposite to the oil pan (46) in a vehicle width direction. The arrangement structure of the exhaust gas sensor of the saddle-ride type vehicle according to the above.
An output sprocket (53) is provided on an output shaft (52) protruding from a crankcase (40) of the power unit (3), and a harness support sprocket cover (60) for covering the output sprocket (53) is provided,
The harness support sprocket cover (60) is characterized in that a coupler stay (65) for fixing a coupler (82a) provided in a harness (82) of the exhaust gas sensor (81) is integrally formed. An exhaust gas sensor arrangement structure for a saddle-ride type vehicle according to any one of claims 1 to 6.