JP6216271B2 - Exhaust pipe with catalyst for saddle-ride type vehicles - Google Patents

Description

  The present invention relates to an exhaust pipe extending from an internal combustion engine mounted on a saddle-ride type vehicle, and more particularly to an exhaust pipe with a catalyst in which a catalyst is interposed.

  Of the exhaust pipes extending from the exhaust port of the internal combustion engine, a catalyst is provided in the upstream exhaust pipe close to the exhaust port, and the catalyst is activated quickly by the action of the high-temperature exhaust gas to increase the purification efficiency. There is an example (refer patent document 1).

JP 2008-190505 A

  In Patent Document 1, an exhaust pipe extending forward from a cylinder head of an internal combustion engine is bent downward immediately and extends along a down frame, bent at a lower end thereof, and extended rearward. A structure in which a metal honeycomb catalyst is interposed in a portion near the exhaust port along the frame is disclosed.

Since the volume of the metal honeycomb catalyst is large, tapered portions that gradually increase in diameter toward the metal honeycomb catalyst are formed before and after the metal honeycomb catalyst of the exhaust pipe.
The high-temperature exhaust gas acts on the catalyst front surface of the metal honeycomb catalyst while expanding at the taper portion on the upstream side, and contracts and flows on the taper portion on the downstream side from the rear surface of the metal honeycomb catalyst.

  As described above, the exhaust pipe structure of Patent Document 1 can be expected to improve exhaust purification efficiency and exhaust efficiency to some extent, but the exhaust gas expands at the taper portion on the upstream side of the metal honeycomb catalyst and is dispersed on the catalyst front surface. However, there is a difference in the flow velocity between the vicinity of the periphery of the metal honeycomb catalyst and the inside thereof, and the flow velocity is disturbed. Similarly, the flow velocity is changed by the taper portion on the downstream side of the metal honeycomb catalyst and exhaust resistance is generated.

  Therefore, it is difficult to increase the exhaust purification efficiency by the metal honeycomb catalyst, and it is difficult to further improve the exhaust efficiency.

  The present invention has been made in view of the above points, and an object of the present invention is exhaust with a catalyst for a saddle-ride type vehicle excellent in assembling ability capable of further improving exhaust gas purification efficiency and exhaust efficiency. The point is to provide a tube.

In order to achieve the above object, the invention according to claim 1
A catalyst that extends from the exhaust port (27) of the internal combustion engine (20) mounted on the saddle-ride type vehicle (1), extends backward through the catalyst (54), and reaches the muffler (60) at the rear of the vehicle body In the attached exhaust pipe,
The upstream exhaust pipe (50U) of the exhaust pipe (50) is connected via a catalyst outer cylinder (53) in which the divided upstream pipe part (51) and downstream pipe part (52) surround the catalyst (54). Is configured,
The upstream exhaust pipe (50U) bends downward at the upper bent pipe portion (51b) as soon as it extends forward from the exhaust port (27) of the internal combustion engine (20) to the front of the internal combustion engine (20). Extending downward along a straight line, bent backward at the lower bent pipe portion (52b) and extended rearward along the bottom surface of the internal combustion engine (20),
The catalyst outer cylinder (53) is interposed in a straight part between the upper bent pipe part (51b) and the lower bent pipe part (52b) in the upstream exhaust pipe (50U),
The outer periphery of the catalyst outer cylinder (53) is covered by a cylindrical cover member (55) supported by the upstream exhaust pipe (50U),
The catalyst outer cylinder (53) has one upstream end (53a) welded and fixed to the upstream pipe (51), and the other downstream end (53b) slid to the downstream pipe (52). Movably mated,
The cylindrical cover member (55) has one upstream end (55a) welded to the upstream pipe (51) and the other downstream end (55b) welded to the downstream pipe (52). a catalyst-exhaust pipe for a saddle type vehicle, characterized in that it is.

The invention according to claim 2
The exhaust pipe with a catalyst of the saddle-ride type vehicle according to claim 1,
The upstream pipe portion (51) passes through the enlarged diameter portion (51aa) formed in the vicinity of the connection portion (51a) from the connection portion (51a) to the exhaust port (27), and the catalyst outer cylinder (53). And extending to the connecting portion (51c) with the catalyst outer cylinder (53).
The invention described in claim 3
In the exhaust pipe with a catalyst of the saddle-ride type vehicle according to claim 1 or 2 ,
The catalyst outer cylinder (53) has one upstream end (53a) fitted to the upstream pipe (51) and the other downstream end (53b) fitted to the downstream pipe (52). In addition, the upstream pipe part (51) and the downstream pipe part (52) are connected.

The invention according to claim 4
In the exhaust pipe with a catalyst of the saddle riding type vehicle according to any one of claims 1 to 3 ,
The upstream exhaust pipe (50U) along the down frame (5) extending slightly obliquely rearwardly downward from the head pipe (3) of the vehicle body frame (2) supporting the internal combustion engine (20). The straight portion where the catalyst outer cylinder (53) is provided is inclined,
One of the engine guards of the left and right engine guard frames (31, 32) projecting from the down frame (5) by being bent in a substantially U shape at the upper horizontal portion, the vertical portion, and the lower horizontal portion on the left and right sides. The catalyst outer cylinder (53) is disposed between the vertical part (32b) substantially parallel to the down frame (5) of the frame (32) and the down frame (5).

The invention according to claim 5
In the exhaust pipe with a catalyst of the saddle riding type vehicle according to claim 4 ,
The lower horizontal portion (32c) of one of the engine guard frames (32) disposed between the catalyst outer cylinder (53) and the down frame (5) wraps around the front of the catalyst outer cylinder (53). It is characterized by surrounding.

According to the exhaust pipe with catalyst of the saddle-ride type vehicle according to claim 2, the upstream exhaust pipe (50U) of the exhaust pipe (50) is divided into a divided upstream pipe portion (51) and downstream pipe portion (52). Are connected via a catalyst outer cylinder (53) surrounding the catalyst (54), and the upstream pipe portion (51) is connected to the exhaust port (27) from the connection portion (51a) to the same connection portion (51a). Through the enlarged diameter portion (51aa) formed in the vicinity of the catalyst outer cylinder (53) and the outer diameter of the catalyst outer cylinder (53) to reach the connection portion (51c) to the catalyst outer cylinder (53), the exhaust port ( 27) The upstream side exhaust pipe (50U) extending from the connection part (51a) to the connection part (51a) has an enlarged diameter part (51aa) in the vicinity of the connection part (51a), and the outer diameter is substantially the same as the catalyst outer cylinder (53). After the diameter is expanded, the exhaust pipe (51), the catalyst outer cylinder (53), and the downstream pipe part (52) continue to have substantially the same inner diameter, and the exhaust gas passes through the catalyst in the catalyst outer cylinder (53) ( 54) Acts evenly throughout, greatly improving the purification efficiency, and exhaust gas on the upstream and downstream sides of the catalyst (54). It can be a flow rate as small as possible the exhaust resistance by eliminating the turbulence of further raising the exhaust efficiency improved engine output.
Further, it is possible to easily connect the upstream pipe portion (51) and the downstream pipe portion (52) via the catalyst outer cylinder (53) having substantially the same inner diameter with a simple connection structure, and the assembling property can be improved. .

According to the exhaust pipe with catalyst of the saddle-ride type vehicle according to claim 3 , one upstream end (53a) of the catalyst outer cylinder (53) is fitted to the upstream pipe (51) and the other downstream side Since the end (53b) is fitted to the downstream pipe (52) and connects the upstream pipe (51) and the downstream pipe (52), the upstream pipe (51) and the downstream pipe (52) In addition, a simple connection structure in which both ends of the catalyst outer cylinder (53) having substantially the same outer diameter can be fitted, and the assemblability can be further improved.

According to the exhaust pipe with catalyst of the saddle-ride type vehicle according to claim 1, the straight portion between the upper bent pipe portion (51b) and the lower bent pipe portion (52b) of the upstream exhaust pipe (50U) Since the catalyst outer cylinder (53) having no taper at both ends is interposed, the proportion of the straight part in the upstream exhaust pipe (50U) is reduced, and the upper bent pipe part (51b) and the lower part are reduced accordingly. The bent pipe portion (52b) can be enlarged to reduce the exhaust resistance, smooth the flow of exhaust gas, and increase the engine output more and more.

According to the exhaust pipe with catalyst of the saddle-ride type vehicle according to claim 1, the outer periphery of the catalyst outer cylinder (53) is covered by the cylindrical cover member (55) supported by the upstream exhaust pipe (50U). The catalyst (54) is double protected by the cylindrical cover member (55) together with the catalyst outer cylinder (53).
The cylindrical cover member (55) covering the catalyst outer cylinder interposed in the straight portion of the upstream side exhaust pipe (50U) is supported by the upstream side exhaust pipe (50U) with its end portion being a linearly extending cylindrical body. It can be formed with a simple configuration, the mounting structure can be simplified, and the production cost can be reduced.

According to the exhaust pipe with catalyst of the saddle-ride type vehicle according to claim 1 , one upstream end (53a) of the catalyst outer cylinder (53) is welded and fixed to the upstream pipe (51), and the other downstream Since the side end portion (53b) is slidably fitted to the downstream pipe portion (52), even if the catalyst outer cylinder (53) is thermally expanded due to heat generation of the catalyst (54), the downstream end portion (53b) And the downstream pipe part (52) is absorbed by the slidable fitting part, and the relative positional relationship between the upstream pipe part (51) and the downstream pipe part (52) is substantially maintained without causing thermal stress, and One upstream end (55a) of the cylindrical cover member (55) accommodating the catalyst outer cylinder (53) is welded to the upstream pipe (51), and the other downstream end (55b) is downstream. A simple structure in which the upstream pipe part (51) and the downstream pipe part (52), which are welded to the pipe part (52) and have little change in positional relationship with each other, are integrated via the cylindrical cover member (55), and the catalyst Maintain the outer shape of the exhaust pipe as a whole against deformation due to temperature changes in (54). It can be.
With a simple exhaust pipe structure, the cost can be reduced.

According to the exhaust pipe with a catalyst of the saddle-ride type vehicle according to claim 4, the vertical part (32b) of the engine guard frame (32) projecting from the down frame (5) by being bent in a substantially U shape laterally. ) And the down frame (5) substantially parallel to each other, the catalyst outer cylinder (53) is disposed, so that the catalyst (54) in the catalyst outer cylinder (53) It is effectively protected by the vertical part (32b) of the guard frame (32) and the down frame (5).

According to the exhaust pipe with catalyst of the saddle-ride type vehicle according to claim 5, the lower horizontal part (32c) of the engine guard frame (32) in which the vertical part (32b) protects the outside of the catalyst outer cylinder (53) is Since it surrounds the catalyst outer cylinder (53) so as to wrap around the front, the catalyst (54) in the catalyst outer cylinder (53) is also protected by the lower horizontal portion (32c) of the engine guard frame (32).

1 is an overall front view of a saddle-ride type motorcycle according to an embodiment of the present invention. 1 is an overall side view of a saddle riding type motorcycle. FIG. Fig. 2 is a partial side view of the saddle riding type motorcycle. It is the IV-IV sectional view taken on the line of FIG. It is the side view made into the partial cross section of the upstream exhaust pipe. It is a longitudinal cross-sectional view of the catalyst part of the upstream exhaust pipe.

Hereinafter, an embodiment according to the present invention will be described with reference to FIGS.
A front view of a saddle-ride type motorcycle 1 according to an embodiment to which the present invention is applied is shown in FIG. 1, an overall side view is shown in FIG. 2, and a partial side view in which a main part is enlarged is shown in FIG.
In the description and claims of the present specification, the front-rear and left-right directions are based on a normal standard in which the straight traveling direction of the saddle-ride type motorcycle 1 according to the present embodiment is the forward direction.

  The body frame 2 of the saddle riding type motorcycle 1 has a main frame 4 extending from the head pipe 3 in the vehicle width direction rearward with a slight inclination and then bent downward to form a main steeply inclined portion 4a. In addition, one down frame 5 extends from the head pipe 3 with the center in the vehicle width direction obliquely rearward and downward.

  The front portion of the crankcase 21 in the internal combustion engine 20 is attached to the lower support bracket 5 b of the down frame 5, and the rear portion of the crankcase 21 is attached to the lower support bracket 4 b of the main steeply inclined portion 4 a of the main frame 4. Thus, the internal combustion engine 20 is supported by the vehicle body frame 2.

  A pair of left and right seat rails 6 extends rearward from the bent portion of the main frame 4 while forming a bent portion in the middle, and the back connecting the bent portion of the seat rail 6 and the central portion of the main steeply inclined portion 4a. A stay 7 supports the seat rail 6.

In the body frame 2 as described above, the front fork 10 is pivotally supported on the head pipe 3, the front wheel 11 is pivotally supported at the lower end thereof, the steering handle 12 is provided at the upper end of the pivot of the front fork 10, and the main frame 4 A rear fork 14 pivotally supported at the front end of a pivot shaft 13 provided at the lower part of the rear shaft extends rearwardly, and a rear wheel 15 is pivotally supported at the rear end thereof, between the center portion of the rear fork 14 and the backstay 7. A rear cushion 16 is interposed.
A fuel tank 17 is installed on the main frame 4 so as to straddle the left and right sides, and a seat 18 is supported by the seat rail 6 behind the fuel tank 17.

  The internal combustion engine 20 mounted on the vehicle body frame 2 is an SOHC type single-cylinder four-stroke internal combustion engine, and is suspended in a standing posture with the crankshaft directed in the vehicle body width direction with respect to the vehicle body and the cylinder slightly tilted forward. Is done.

  The internal combustion engine main body of the internal combustion engine 20 has a cylinder block 22 and a cylinder head 23 that are sequentially stacked on a diagonally upper side of a crankcase 21 that rotatably supports a crankshaft (not shown) oriented in the left-right direction. , 72 are integrally fastened, and a cylinder head cover 24 is covered on the cylinder head 23. The cylinder block 22, the cylinder head 23, and the cylinder head cover 24 protrude slightly forward from the crankcase 21. Has been established.

  A down frame 5 extends downwardly and obliquely rearwardly from the head pipe 3 along the front surface of the forwardly inclined internal combustion engine main body, and left and right engine guard frames 31, 32 from the down frame 5 to the left and right sides. Are projected.

  Referring to FIG. 1, left and right engine guard frames 31, 32 are bent in a substantially U-shape at upper horizontal portions 31a, 32a, vertical portions 31b, 32b, and lower horizontal portions 31c, 32c. End portions of the upper horizontal portions 31a and 32a are fixed to the upper support bracket 30a provided on the upper portion of the lower frame, and end portions of the lower horizontal portions 31c and 32c are attached to the lower support bracket 30b provided on the lower portion of the down frame 5. Is fixed, and the left and right vertical portions 31b and 32b are provided so as to protrude greatly to the left and right sides.

The vertical parts 31b and 32b of the left and right engine guard frames 31 and 32 are substantially parallel to the down frame 5 extending slightly obliquely rearwardly downward from the head pipe 3 in a side view (FIG. 2) and slightly obliquely rearwardly from the upper part to the lower part. Inclined.
The front of the internal combustion engine 20 is protected by left and right engine guard frames 31 and 32 projecting from the down frame 5 to the left and right sides.

Referring to FIG. 2, an intake pipe 40 is connected to an intake port 26 extending rearward from the combustion chamber of the cylinder head 23 and extends rearward from the rear surface of the cylinder head 23. The intake pipe 40 is connected via a carburetor 41. The air cleaner 42 is connected (see FIG. 1).
On the other hand, from the front surface of the cylinder head 23 connected to the exhaust port 27 extending forward from the combustion chamber 25, an exhaust pipe 50 extends diagonally forward to the right.

  The exhaust pipe 50 extending from the front surface of the cylinder head 23 obliquely forward to the right is bent downward and extends the right side of the down frame 5 obliquely backward to the rear, and then bent rearward along the lower surface of the internal combustion engine body. And is connected to a muffler 60 that is inclined slightly to the right side of the rear wheel 15 and oriented in the front-rear direction.

Here, the exhaust pipe 50 is connected to the upstream exhaust pipe 50U from the connection portion with the exhaust port 27 to the lower bent portion, and from the lower bent portion to the diffuser pipe 59 at the downstream end inserted into the muffler 60. The downstream exhaust pipe 50L.
The upstream side exhaust pipe 50U is configured by connecting a divided upstream pipe portion 51 and downstream pipe portion 52 via a catalyst outer cylinder 53 surrounding a metal honeycomb catalyst 54.

The upstream pipe portion 51 of the upstream side exhaust pipe 50U is bent downward by the upper bent pipe portion 51b from the upstream connection pipe portion 51a connected to the exhaust port 27 to the downstream fitting pipe portion 51c fitted to the catalyst outer cylinder 53.
The downstream pipe portion 52 of the upstream exhaust pipe 50U bends backward from the upstream fitting pipe portion 52a fitted to the catalyst outer cylinder 53 at the lower bent pipe portion 52b and continues to the downstream exhaust pipe 50L.

  Between the upper bent pipe portion 51b of the upstream pipe portion 51 and the lower bent pipe portion 52b of the downstream pipe portion 52, the right side of the down frame 5 extends linearly downward and obliquely rearward substantially parallel to the down frame 5. A catalyst outer cylinder 53 surrounding the metal honeycomb catalyst 54 is interposed in the straight part (see FIG. 3).

  The exhaust pipe 50 is configured with almost the same predetermined outer diameter (and inner diameter), and the upstream pipe section 51 and the downstream pipe section 52 of the upstream exhaust pipe 50U have the same predetermined outer diameter, The inner diameter of the catalyst outer cylinder 53 interposed therebetween is substantially equal to the predetermined outer diameter of the upstream exhaust pipe 50U, and the upstream end 53a of the catalyst outer cylinder 53 is connected to the upstream pipe section 51 as shown in FIG. And the downstream end portion 53b of the catalyst outer cylinder 53 is fitted to the upstream fitting tube portion 52a of the downstream tube portion 52.

  The upstream end portion 53 a of the catalyst outer cylinder 53 is welded and integrated with the downstream fitting pipe portion 51 c of the upstream pipe portion 51, but the downstream end portion 53 b of the catalyst outer cylinder 53 is integrated with the downstream pipe portion 52. The catalyst outer cylinder 53 and the downstream pipe part 52 are slidably fitted to each other without being welded to the upstream fitting pipe part 52a.

Since the upstream pipe 51, the downstream pipe 52, and the catalyst outer cylinder 53 are all thin, the inner diameter (flow diameter) from the upstream pipe 51 through the catalyst outer cylinder 53 to the downstream pipe 52 is the outside of the catalyst. The tube 53 is extremely slightly thicker than the wall thickness, and communicates with substantially the same diameter as the ventilation diameter.
The metal honeycomb catalyst 54 is fitted into the central portion of the catalyst outer cylinder 53 excluding the upstream end 53a and the downstream end 53b.

The outer periphery of the catalyst outer cylinder 53 is covered with a cylindrical cover member 55.
Referring to FIGS. 5 and 6, the cylindrical cover member 55 has the same central axis as the catalyst outer cylinder 53 and is disposed outside the catalyst outer cylinder 53 with a large annular gap, with both ends tapered. An upstream taper end 55a and a downstream taper end 55b extending in a taper are formed.

As shown in FIG. 6, the upstream taper end portion 55a is located on the upstream side of the upstream end portion 53a of the catalyst outer cylinder 53, and the upstream pipe portion is located on the upstream opening end of the upstream taper end portion 55a. 51 is inserted.
Similarly, the downstream taper end portion 55b is positioned downstream of the downstream end portion 53b of the catalyst outer cylinder 53, and the downstream pipe portion 52 is fitted into the downstream opening end of the downstream taper end portion 55b. ing.

Then, the fitting portion between the upstream opening end of the upstream taper end portion 55a and the upstream pipe portion 51 is welded, and the fitting portion between the downstream taper end portion 55b and the downstream opening end is welded.
The upstream opening end of one upstream taper end portion 55 a of the cylindrical cover member 55 is welded to the downstream portion of the upstream pipe portion 51, and the downstream opening end of the other downstream taper end portion 55 b is the downstream pipe portion 52. By welding to the upstream portion, the upstream pipe portion 51 and the downstream pipe portion 52 are integrated via the cylindrical cover member 55.

  The upstream pipe portion 51 of the upstream side exhaust pipe 50U is connected to the catalyst outer cylinder 53 through an enlarged diameter portion 51aa formed in the vicinity of the upstream connection pipe portion 51a from the upstream connection pipe portion 51a which is a connection portion with the exhaust port 27. It has a shape that reaches substantially the same outer diameter and extends to the downstream fitting tube portion 51c that is a connecting portion with the catalyst outer cylinder 53 (see FIG. 5).

Referring to FIG. 5, the joint member 57 is formed by superimposing a cylindrical mouth collar 56 having an inner diameter equal to the outer diameter of the upstream connecting pipe portion 51a and a joint member 57, which is an annular plate member having a larger inner diameter. The upstream connecting pipe part 51 a reduced in diameter from the side is inserted, fitted into the mouse collar 56, and fixed to the inner peripheral surface of the mouse collar 56 by welding.
The upstream pipe portion 51 extends to the outside from the upstream connection pipe portion 51 a welded to the mouse collar 56 through a diameter-enlarged portion 51 aa that is enlarged inside the joint member 57 having an inner diameter larger than that of the mouse collar 56.

  Bolt bosses that are formed on both sides of the opening end face of the exhaust port 27 of the cylinder head 23 (the end face of the mouse collar 56 overlaps the opening end face of the exhaust port 27 that opens to the front face of the cylinder head 23 via a gasket). (Not shown), the fastening portion 57b of the joint member 57 is brought into contact, the fastening bolt 58 is inserted into the bolt hole of the fastening portion 57b, and is screwed into the female screw hole of the bolt boss portion to be tightened. The upstream end of the exhaust pipe 50 is fixed to the open end (see FIG. 3).

Referring to FIGS. 3 and 4, the upstream side exhaust pipe 50U of the exhaust pipe 50 extends from the exhaust port 27 of the cylinder head 23 obliquely forward and to the right and bends obliquely downward at the upper curved pipe portion 51b. A cylindrical cover member 55 is disposed in a straight line portion extending obliquely rearward and downward on the left side of the vertical portion 32b of the right engine guard frame 32 on the right side.
Then, the front side of the cylindrical cover member 55 is enclosed so that the lower horizontal portion 32c of the right engine guard frame 32 turns around (see FIG. 4).

  That is, the cylindrical cover member 55 and the catalyst outer cylinder 53 in the cylindrical cover member 55 are sandwiched between the down frame 5 and the vertical portion 32b of the right engine guard frame 32, and the lower horizontal portion 32c of the right engine guard frame 32. The front is enclosed and protected.

  Since the exhaust pipe 50 extending from the exhaust port 27 of the internal combustion engine 20 is provided with the metal honeycomb catalyst 54 in the upstream exhaust pipe 50U close to the exhaust port 27, the metal honeycomb catalyst is subjected to the action of high-temperature exhaust gas. It can be activated quickly to increase purification efficiency.

The upstream exhaust pipe 50U of the exhaust pipe 50 is configured by connecting the divided upstream pipe portion 51 and the downstream pipe portion 52 via a catalyst outer cylinder 53 surrounding the metal honeycomb catalyst 54, and the upstream pipe portion 51 extends from the upstream connecting pipe portion 51a to the exhaust port 27 through the enlarged diameter portion 51aa formed in the vicinity of the upstream connecting pipe portion 51a, and has an outer diameter substantially the same as that of the catalyst outer cylinder 53. Therefore, the upstream side exhaust pipe (50U) extending from the upstream connection pipe part 51a which is the connection part to the exhaust port 27 is connected to the upstream connection pipe part 51a. Thus, after the outer diameter is expanded to substantially the same inner diameter as that of the catalyst outer cylinder 53, the upstream pipe portion 51, the catalyst outer cylinder 53, and the downstream pipe portion 52 continue to have substantially the same inner diameter. It acts on the entire metal honeycomb catalyst 54 in the inside to greatly improve the purification efficiency, and at the upstream and downstream of the metal honeycomb catalyst 54 As small as possible to exhaust efficiency flow rate disturbance exhaust resistance by eliminating the exhaust gas at it is possible to further improve the engine output by increasing the.
Further, it is possible to easily connect the upstream pipe portion 51 and the downstream pipe portion 52 via the catalyst outer cylinder 53 having substantially the same inner diameter with a simple connection structure, and the assemblability can be improved.

  In the catalyst outer cylinder 53, one upstream end 53a is fitted to the upstream pipe 51, and the other downstream end 53b is fitted to the downstream pipe 52, so that the upstream pipe 51 and the downstream pipe 52 are fitted. Therefore, it is possible to provide a simple connection structure in which both ends of the catalyst outer cylinder 53 having substantially the same outer diameter are fitted to the upstream pipe portion 51 and the downstream pipe portion 52, and the assemblability can be further improved. it can.

Since the catalyst outer cylinder 53 having no taper portions at both ends is interposed in a straight portion between the upper bent pipe portion 51b and the lower bent pipe portion 52b of the upstream exhaust pipe 50U, the upstream exhaust pipe 50U By reducing the proportion of the straight portion, the upper bent pipe portion 51b and the lower bent pipe portion 52b can be enlarged correspondingly to reduce the exhaust resistance, thereby smoothing the flow of exhaust gas and increasing the engine output.

Since the outer periphery of the catalyst outer cylinder 53 is covered with the cylindrical cover member 55 supported by the upstream side exhaust pipe 50U, the metal honeycomb catalyst 54 is double-protected by the cylindrical cover member 55 together with the catalyst outer cylinder 53.
The cylindrical cover member 55 covering the catalyst outer cylinder 53 interposed in the straight portion of the upstream side exhaust pipe 50U is formed with a simple configuration in which the end portion is supported by the upstream side exhaust pipe 50U with a linearly extending cylindrical body. The mounting structure can be simplified and the production cost can be reduced.

  The catalyst outer cylinder 53 has one upstream end 53a welded and fixed to the upstream pipe portion 51 and the other downstream end 53b slidably fitted to the downstream pipe portion 52, so that the metal honeycomb catalyst 54 Even if the catalyst outer cylinder 53 is thermally expanded due to the heat generation of the upstream pipe portion 51 and the downstream pipe portion, the downstream end portion 53b and the downstream pipe portion 52 are absorbed by the slidable fitting portion without causing thermal stress. The relative positional relationship of 52 hardly changes.

Then, one upstream end 55a of the cylindrical cover member 55 that accommodates the catalyst outer cylinder 53 is welded to the upstream pipe part 51, and the other downstream end 55b is welded to the downstream pipe part 52. The temperature change of the metal honeycomb catalyst 54 is a simple structure in which the upstream pipe part 51 and the downstream pipe part 52 are integrated with each other via the cylindrical cover member 55 so that the positional relationship hardly changes with respect to the thermal expansion of the outer cylinder 53. On the other hand, the outer shape of the exhaust pipe as a whole can be substantially maintained without being deformed.
Cost reduction can be achieved by a simple exhaust pipe structure.

  A cylindrical cover member 55 is disposed between the vertical part 32b of the right engine guard frame 32 projecting from the down frame 5 to the side in a substantially U-shape and the down frame 5 substantially parallel to each other. Since the catalyst outer cylinder 53 in the cylindrical cover member 55 is disposed, the metal honeycomb catalyst 54 in the catalyst outer cylinder 53 has a vertical portion 32b of the right engine guard frame 32 and the down frame 5 which are substantially parallel to each other on the left and right sides. Is effectively protected.

  The lower horizontal portion 32c of the right engine guard frame 32 that protects the outside of the cylindrical cover member 55 by the vertical portion 32b surrounds the cylindrical cover member 55, that is, the front of the catalyst outer cylinder 53 in the cylindrical cover member 55. Therefore, the catalyst 54 in the catalyst outer cylinder 53 is also protected from the front by the lower horizontal portion 32c of the right engine guard frame 32.

1 ... saddle riding type motorcycle, 2 ... body frame, 3 ... head pipe, 4 ... main frame, 5 ... down frame,
20 ... Internal combustion engine, 21 ... Crankcase, 22 ... Cylinder block, 23 ... Cylinder head, 25 ... Combustion chamber, 26 ... Intake port, 27 ... Exhaust port,
30a ... Upper support bracket, 30b ... Lower support bracket, 31 ... Left engine guard frame, 32 ... Right engine guard frame, 32b ... Vertical part, 32c ... Lower horizontal part,
50 ... exhaust pipe, 50U ... upstream exhaust pipe, 50L ... downstream exhaust pipe, 51 ... upstream pipe section, 51a ... upstream connection pipe section, 51aa ... expanded diameter section, 51b ... upper curved pipe section, 51c ... downstream fitting Pipe part, 52 ... downstream pipe part, 52a ... upstream fitting pipe part, 52b ... lower bent pipe part, 53 ... catalyst outer cylinder, 54 ... metal honeycomb catalyst, 55 ... cylindrical cover member, 56 ... mouse collar, 57 ... Joint members, 58 ... fastening bolts, 59 ... diffuser pipes, 60 ... mufflers.

Claims (5)

A catalyst that extends from the exhaust port (27) of the internal combustion engine (20) mounted on the saddle-ride type vehicle (1), extends backward through the catalyst (54), and reaches the muffler (60) at the rear of the vehicle body In the attached exhaust pipe,
The upstream exhaust pipe (50U) of the exhaust pipe (50) is connected via a catalyst outer cylinder (53) in which the divided upstream pipe part (51) and downstream pipe part (52) surround the catalyst (54). Is configured,
The upstream exhaust pipe (50U) bends downward at the upper bent pipe portion (51b) as soon as it extends forward from the exhaust port (27) of the internal combustion engine (20) to the front of the internal combustion engine (20). Extending downward along a straight line, bent backward at the lower bent pipe portion (52b) and extended rearward along the bottom surface of the internal combustion engine (20),
The catalyst outer cylinder (53) is interposed in a straight part between the upper bent pipe part (51b) and the lower bent pipe part (52b) in the upstream exhaust pipe (50U),
The outer periphery of the catalyst outer cylinder (53) is covered by a cylindrical cover member (55) supported by the upstream exhaust pipe (50U),
The catalyst outer cylinder (53) has one upstream end (53a) welded and fixed to the upstream pipe (51), and the other downstream end (53b) slid to the downstream pipe (52). Movably mated,
The cylindrical cover member (55) has one upstream end (55a) welded to the upstream pipe (51) and the other downstream end (55b) welded to the downstream pipe (52). An exhaust pipe with a catalyst for a saddle-ride type vehicle. The upstream pipe portion (51) passes through the enlarged diameter portion (51aa) formed in the vicinity of the connection portion (51a) from the connection portion (51a) to the exhaust port (27), and the catalyst outer cylinder (53). The exhaust pipe with catalyst for a saddle-ride type vehicle according to claim 1, wherein the exhaust pipe has a substantially same outer diameter and extends to a connecting portion (51c) with the catalyst outer cylinder (53). The catalyst outer cylinder (53) has one upstream end (53a) fitted to the upstream pipe (51) and the other downstream end (53b) fitted to the downstream pipe (52). The exhaust pipe with a catalyst for a saddle-ride type vehicle according to claim 1 or 2 , wherein the upstream pipe section (51) and the downstream pipe section (52) are connected together. The upstream exhaust pipe (50U) along the down frame (5) extending slightly obliquely rearwardly downward from the head pipe (3) of the vehicle body frame (2) supporting the internal combustion engine (20). The straight portion where the catalyst outer cylinder (53) is provided is inclined,
One of the engine guards of the left and right engine guard frames (31, 32) projecting from the down frame (5) by being bent in a substantially U shape at the upper horizontal portion, the vertical portion, and the lower horizontal portion on the left and right sides. between the frame (32) the down frame (5) substantially parallel to said vertical sites (32 b) and the down frame (5), wherein, wherein the catalyst outer cylinder (53) is arranged The exhaust pipe with a catalyst for a saddle-ride type vehicle according to any one of claims 1 to 3 . The lower horizontal portion (32c) of one of the engine guard frames (32) disposed between the catalyst outer cylinder (53) and the down frame (5) wraps around the front of the catalyst outer cylinder (53). The exhaust pipe with a catalyst for a saddle-ride type vehicle according to claim 4, wherein the exhaust pipe is enclosed in the manner described above.

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