JPH0223778Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to an exhaust pipe structure used in motorcycles and the like.

(Prior art) The exhaust port of the engine of a motorcycle often faces toward the front of the vehicle body due to its structure. In this case, the exhaust pipe has a bent pipe section that is bent into a substantially U-shape near the exhaust port of the engine, and a connecting pipe section that is connected to a muffler that is provided continuously to the bent pipe section. .

By the way, when trying to form a curved pipe section of an exhaust pipe by bending a straight pipe, the radius of curvature of the curved pipe section is 2.5% of the diameter of the straight pipe, due to the finish condition, strength, etc. required for the curved pipe section. It needs to be more than double.
Therefore, when forming an exhaust pipe by bending a straight pipe, the radius of curvature of the bent pipe becomes large, and the connecting pipe has to be located quite far away from the engine, which means it cannot be placed below or on the side of the vehicle body. As the exhaust pipe protrudes toward the side, the space occupied by the exhaust pipe becomes larger, and it also poses a problem for the rider when driving. For this purpose, a pair of gutter-like members are formed that are divided along the plane along the central axis of the exhaust pipe, and a joint flange that protrudes outward over the entire length in the axial direction is formed on both side edges of both gutter-like members. In some cases, the joint flanges are welded together to form an exhaust pipe. A collar that contacts the exhaust port of the engine is welded to one end of the curved pipe part of the exhaust pipe, and a fixing member for attaching the exhaust pipe cover is attached to the connecting pipe part in the longitudinal direction of the circumferential surface. A plurality of them are provided at intervals and protrude outward. This exhaust pipe is connected to the engine in the following manner. That is, a collar welded to one end of the bent pipe section is brought into contact with the cylinder head of the engine via a gasket, and then a holder is inserted from the rear end of the connecting pipe section and engaged with the shoulder of the collar. The holder is bolted to the cylinder head and connected to the engine. In this case, the holder must not only be larger than the outer diameter of the exhaust pipe, but also have an inner diameter that can simultaneously exceed the two joint flanges on the left and right sides and the fixing member provided on the connecting pipe section. For this reason, if the inside diameter of the holder is set to a value that allows it to pass over the two joint flanges on the left and right sides of the exhaust pipe, the height of the fixing member will be limited to less than the overhang width of one joint flange, and the exhaust pipe cover will There was a problem that sufficient mounting strength could not be ensured. Additionally, if the height of the fixing member is made higher than the overhanging width of one joint flange, the inner diameter of the holder must be increased accordingly. Requires a lot of space. On the other hand, if the holder is attached to the bent pipe section in advance and then the connecting pipe section is connected, the painting workability is poor, and the holder must be manufactured before connecting the bent pipe section and the connecting pipe section. There is a problem that division of labor becomes difficult because the work process is restricted.

(Purpose of the invention) The present invention was made in view of the above circumstances, and it is possible to reduce the inner diameter of the holder, and
The purpose is to provide an exhaust pipe that is easy to manufacture and can be supplied at low cost.

(Structure of the invention) The structure of the invention consists of a bent pipe section with one end connected to the exhaust port of the engine and the other end directed toward the rear of the vehicle body, and both ends connected to the other end of the bent pipe section and the muffler at the rear of the vehicle body. A ring-shaped holder inserted from the rear end of the connecting pipe part is engaged with a collar fixed to one end of the bent pipe part, and the holder is attached to the engine by fastening to the cylinder head. The curved pipe section is a pipe body having a pair of seam flanges that protrude outward on the diameter line of the pipe and are joined together, and the connecting pipe section is composed of a seamless pipe and has a circumferential surface. is provided with a plurality of fixing members projecting outward at intervals in the longitudinal direction, and the holder is eccentric to the tube axis of the connecting pipe portion at the fixing member attachment position to hold the fixing members. This relates to an exhaust pipe structure of a motorcycle in which the exhaust pipe cover passes through the curved pipe side and is attached to this fixing member.

(Example) The present invention will be described below with reference to the drawings.

FIG. 1 shows an overall view of a motorcycle, in which 1 is an exhaust pipe according to the present invention, 2 is an engine, 3 is a muffler, and 4 is an exhaust pipe according to the present invention.
is a handle, 5 is a front wheel, and 6 is a rear wheel. The exhaust pipe 1 has one end connected to an engine 2 and a rear end connected to a muffler 3.

FIG. 2 shows the exhaust pipe 1 and the muffler 3. The exhaust pipe 1 includes a curved pipe section 10 formed in a substantially U-shape, and a connecting pipe section 11 whose both ends are connected to the other end 10b of the curved pipe section 10 and the muffler 3. A collar 14 is fixed to one end 10a of the bent pipe section 10, and a nut is attached to the circumferential surface of the connecting pipe section 11 as a fixing member for attaching the exhaust pipe cover 9 (Figs. 1, 3, 4, and 5). Members 15a and 15b are provided at at least two locations spaced apart in the longitudinal direction of the exhaust pipe. In FIG. 2, reference numerals 8a, 8b, and 8c are brackets for attaching the exhaust pipe 1 and the muffler 3 to the vehicle body frame.

3 and 4 show the exhaust pipe 1. FIG.

The bent pipe section 10 is made of stainless steel, has an outer diameter D of 35 mm, and a radius of curvature R (Fig. 5) of 50 mm.
mm. The bent pipe portion 10 includes a pair of gutter-like members 12,1
Consists of 3. The pair of gutter-like members 12 and 13 have a shape in which the curved pipe section 10 is divided into two parts passing along the diameter line thereof. In this example, it is divided into two by a symmetry plane passing on the diameter line. On both side edges of each gutter-like member 12, 13, a joint flange 12a,
12b, 13a, and 13b are formed. Then, the joint flange 12a and the joint flange 13a of both the gutter-like members 12 and 13 are welded, and the joint flange 12b and the joint flange 13b are welded to form the bent pipe portion 10. However, the bent pipe part 10
may be divided into three or more parts along a plane passing along the radial line of the tube.

The connecting pipe portion 11 is made of ordinary steel and is formed of a seamless pipe. The other end portion 10b of the curved tube portion 10 is fitted into the distal end portion 11a of the connecting tube portion 11, and the periphery of this fitting portion is welded and connected. The rear end portion 11b of the connecting pipe portion 11 is connected to the muffler 3.
is connected to. Also, the height h of each nut member 15a, 15b provided on the peripheral surface of the connecting pipe portion 11 is
(FIG. 6) shows joint flanges 12a, 12b, 13a, 13b projecting on both sides of the bent pipe section 10.
The value is slightly lower than the value 2S (FIG. 7) of the sum of both overhang widths.

FIG. 5 shows a state in which the exhaust pipe 1 having the above structure is attached to the engine 2.

The collar 14 fixed to one end of the bent pipe section 10 is attached to the gasket 1 to the cylinder head section 2a of the engine 2.
6, so that the exhaust pipe 1 and the exhaust port 2b of the engine 2 face each other. Next, the holder 7 is engaged with the shoulder portion of the collar 14, and the holder 7 is attached to the cylinder head portion 2a with bolts 18.

Note that the holder 7 is assembled after welding each part of the exhaust pipe.
It is fitted from the rear end portion 11b of the connecting pipe portion 11. In addition, the inner diameter of the holder 7 is the same as that of the joint flange 12.
Bent pipe section 10 including a, 12b, 13a, and 13b
The width is large enough to pass through. and,
When the holder 7 passes through the nut member 15a of the connecting pipe section 11, this connecting pipe section 11 has no joint flange, and the height h of the nut members 15a, 15b is equal to the sum of the overhanging widths of the joint flanges, 2S. Since the holder 7 is formed slightly lower, the holder 7 is eccentrically moved toward the nut member 15a and passed toward the bent pipe portion 10, as shown in FIG. Further, when the holder 7 passes through the bent tube section 10, the holder 7 is passed through the bent tube section 10 with the holder 7 concentrically formed as shown in FIG. In this way, the inner diameter of the holder 7 is
Even if the height h of the nut members 15a, 15b is large enough to pass through the width of the bent pipe section 10 including the width of the joint flange 12a, 12b, 13
It is possible to increase the overhang width of both a and 13b to nearly 2S. After attaching the holder 7 to the cylinder head 2a in this way, the exhaust pipe cover 9
are applied to the connecting pipe part 11, and the bolts 19, 19 (fourth
It is attached as shown in the figure). This nut member 15a, 1
5b may be replaced with a bolt, and other fixing means may be used, such as screwing a nut onto the bolt.

(Effects of the invention) As explained above, according to the invention, the curved pipe part is a pipe body having a pair of seam flanges that protrude outward on the diameter line of the pipe and are joined together, and the connecting pipe part is a Since the exhaust pipe is made of a seamless pipe with a plurality of fixing members provided at intervals in the longitudinal direction, the inner diameter of the holder inserted into the exhaust pipe is
When passing through the connecting pipe section, it is possible to cross over the fixing member protruding from the circumferential surface of the connecting pipe section, and when passing through the bent pipe section, it is possible to cross over the joint flanges that protrude on both sides of the bent pipe section. I wish I could. Therefore, the height of the fixing member provided near the bent pipe portion can be increased to approximately the sum of the overhang widths on both sides of the joint flange, ensuring sufficient mounting strength for the exhaust pipe cover. be able to. Further, unlike conventional exhaust pipes, it is not necessary to go over the fixing member and the joint flange at the same time, so the inner diameter of the holder can be made considerably small, and the holder itself can be small. As a result, the space required for the holder mounting part is small, and the holder can be kept separate during painting work, and the bent pipe part and the connecting pipe part can be manufactured in advance and connected directly. Since the holder can be attached later, there are fewer restrictions on the manufacturing process, such as a separate process for just the holder.

In addition, since the gutter-like member is only the bent pipe part, the mold can be small, and since the connecting pipe part continuous to the bent pipe part is a seamless pipe, manufacturing costs such as mold costs and material costs can be reduced. can.

[Brief explanation of the drawing]

Figure 1 is a side view of the motorcycle, Figure 2 is a perspective view of an exhaust pipe and muffler illustrating an embodiment of the present invention, Figure 3 is a perspective view of the exhaust pipe shown in Figure 2, and Figure 4 is a perspective view of the exhaust pipe shown in Figure 2.
The figure is a front view of the exhaust pipe shown in Figure 3, Figure 5 is an enlarged plan view with main parts cut away with the exhaust pipe attached to the engine, and Figure 6 is a diagram showing the holder inserted into the connecting pipe part of the exhaust pipe. FIG. 7 is a cross-sectional view taken in a direction perpendicular to the central axis of the connecting pipe portion to explain the state, and FIG. 1...Exhaust pipe, 2...Engine, 3...Muffler, 9...Exhaust pipe cover, 10...Bent pipe section, 11
... Connecting pipe section, 14 ... Collar, 15a, 15b
...Natsuto parts.

Claims (1)

[Scope of utility model registration request] A bent pipe part with one end connected to the exhaust port of the engine and the other end directed toward the rear of the vehicle body, and a connecting pipe part with both ends connected to the other end of the bent pipe part and the muffler at the rear of the vehicle body. An annular holder inserted from the rear end of the tube is engaged with a collar fixed to one end of the bent tube,
The exhaust pipe is attached to the engine by fastening this holder to the cylinder head, and the curved pipe part is a pipe body having a pair of joint flanges that protrude outward on the diameter line of the pipe and are joined together, and the connecting pipe part is composed of a seamless pipe, and a plurality of fixing members protruding outward at intervals in the longitudinal direction are provided on the circumferential surface, and the holder is attached to the connecting pipe section at the fixing member attachment position. An exhaust pipe structure for a motorcycle, characterized in that the fixing member passes eccentrically with respect to the pipe axis toward the curved pipe portion, and an exhaust pipe cover is attached to the fixing member.