JPS637252B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in the exhaust pipe of a motorcycle equipped with a side V-type engine.

For motorcycles equipped with a 2-cylinder or 4-cylinder engine with a V-shaped side, the exhaust pipe connected to the front cylinder and the exhaust pipe connected to the rear cylinder are connected to a collective chamber located behind the engine. However, in order to make the length of the exhaust pipe connected to the rear cylinder substantially the same as that of the exhaust pipe connected to the front cylinder, it is necessary to connect the end of the rear exhaust pipe to an extension pipe provided in the collecting chamber.

By doing so, the engine characteristics of the rear cylinder can be matched to the engine characteristics of the front cylinder.

By the way, it is generally known that high-speed engines lack torque in the medium speed range. Therefore, it is desirable to increase the torque in the medium speed range as well as the low speed range, and it is also necessary to ensure torque in the high speed range. It is preferable to make it possible to accomplish the following.

The present invention has been made in response to such a demand, and its purpose is to provide a chamber in the collecting chamber of a motorcycle equipped with a V-shaped side engine, and to connect to an exhaust port on the back of the rear cylinder. By simply modifying the extension pipe that communicates with the exhaust pipe, you can increase the torque in the low speed range of the engine, and
To provide an exhaust pipe for a motorcycle that guarantees torque in a high speed range and also increases torque in a medium speed range.

In order to achieve the above object, the present invention has an exhaust pipe connected to a rear cylinder of a side V-type engine extending into the collecting chamber, and an outlet end of an extension pipe formed to extend into the collecting chamber is narrowed, and the collecting chamber of the extension pipe is The gist is that a small diameter hole is formed inside the chamber.

A preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 is a side view of the motorcycle, FIG. 2 is a side view of the engine and exhaust pipe portion, and FIG. 3 is an exploded perspective view of the exhaust pipe, the inside of the collecting chamber, and the muffler.

A head tube 3 is provided at the front end of a body frame 2 of a motorcycle 1, a front fork 5 supporting a front wheel 4 is supported on the head tube 3 in a freely steerable manner, and a handle 7 is provided on a top bridge 6.

The vehicle body frame 2 forms a pair on the left and right sides, and includes a main pipe 21 extending from the rear upper part of the head tube 3 to the rear of the side, and a down tube 2 hanging down from the rear lower part of the head tube 3 to the rear and lower side of the head tube 3.
2. A down tube blower 23 that extends rearward from the lower end of the down tube blower 22; A center tube 2 that extends forward and upward from the rear end of the down tube blower 23 and continues to the rear end of the main pipe 21;
4. It consists of a seat rail 25 that extends rearward of the main pipe 21, and a rear stay 26 that connects the substantially central part of the seat rail 25 and the lower part of the center tube 24 and is installed tilting backwards. These left and right frame members are square pipes with a vertically elongated rectangular cross section obtained by press-forming steel plates, and are connected to each other by a cross member.

A fuel tank 8 is installed across the main pipes 21, 21 that constitute the vehicle body frame 2, and a seat 9 is placed on the seat rails 25, 25, and when viewed from the side, the main pipe 21, down tube 22, The engine 10 is mounted in the space surrounded by the down tube blower 23 and the center tube 24, and the engine 10 has two cylinders 10 in the front and rear.
It is a 4-cylinder engine with V-shaped sides with 1,101 and 102,102 sides. The firing order of this engine 10 is first the right front cylinder, second the right rear cylinder, and third the left front cylinder.
Last is the left rear cylinder, and the direction of rotation of the crankshaft is forward rotation as indicated by the arrow in FIG.

On the other hand, the rear fork 12 that supports the rear wheel 11 is pivotally supported 13 on a mid-shaped gusset 27 fixed to the front surface of the center tube 24, and there is a space (not shown) between the rear fork 12 and the cross member of the seat rails 25, 25. A reaction unit is provided.

Note that the front cylinders 101, 101 of the engine 10
A carburetor 14 is arranged in the V-shaped bank formed by the rear cylinders 102 and 102, and the carburetor 14 is connected to each cylinder 101 and 102 by a connecting tube 15.
... are connected to each other. Matadown tube 2
An upper radiator 16 and a lower radiator 17 are installed in front of 2 and 22.

and the front cylinder 101,1 of the engine 10
01, exhaust pipes 30, 40 are connected to the down tube 22 through gaskets 31, 41 at joints 42, 42, respectively.
Exhaust pipes 30 and 40 extend to the rear and lower part of the engine 10 along the front lower part of the engine 10 and the lower part of the down tube blower 23. It is connected.

This collective chamber 50 is supported at the lower rear of the engine 10 by bolts 51, 51, and the left and right mufflers 50
The mufflers 52, 52 are connected to the left and right sides of the rear surface via gaskets 53, 53 and bands 54, 54 and bolts 55, 55, respectively, and the mufflers 52, 52 are connected to the rear stay with bolts and nuts 56, 56, respectively. 2
6, 26 are supported by pillion step brackets 18, 18 fixed to the lower part thereof.

By the way, the rear cylinder 102 of the engine 10,
Exhaust pipes 60 and 80 having the same inner diameter as the front exhaust pipe are also connected to the rear surface of the exhaust pipe 102 at joints 62 and 82 via gaskets 61 and 81, respectively, and the exhaust pipes 60 and 80 are bent downward and suspended, respectively. Bands 64, 84 and bolts 65, 85 are connected to upper ends of extension pipes 70, 90 having the same inner diameter as the exhaust pipes, which are protruded from the left and right sides of the rear upper surfaces of the collecting chambers 50, 50, respectively, through gaskets 63, 83. It is connected. As a result, the extension pipes 70, 90 are connected to the exhaust pipe 60,
80, respectively.

The extension pipe 7 forming the downstream side of the exhaust pipes 60, 80 connected to the rear cylinders 102, 102 in this way
0 and 90 are respectively assembled chambers 50 as follows.
It is formed to extend inward. This will be explained in detail with reference to FIGS. 4 to 10.

First, an extension pipe 90 constituting the downstream side of the exhaust pipe 80 connected to the right rear cylinder 102 is formed to extend forward in the collection chamber 50, and further to the left, with the outlet end 93 facing slightly rearward and upward. The above portions are continuously curved to form an upstream curved extension portion 91 and an exit curved extension portion 92, respectively. The outlet end 93 of this extension pipe 90 is formed with a constriction 94, and this constriction is set to have a cross-sectional area of 60% to 80% of the diameter of the extension pipe.

Next, an extension pipe 70 constituting the downstream side of the exhaust pipe 60 connected to the left rear cylinder 102 is formed to extend toward the right side inside the collecting chamber 50, and is further directed forward so that the outlet end 73 is slightly upwardly leftward. Similarly to the above, these portions are continuously curved to form an upstream curved extension portion 71 and an exit curved extension portion 72, respectively. The outlet end 73 of this extension pipe 70 is also 60% of the extension pipe diameter.
Aperture formation 74 is performed with a cross-sectional area of ~80%.

The left and right extension tubes 70, 90 are curved as described above so that their exhaust resistances are the same.

Therefore, while the engine 10 is running, the exhaust pipes 60, 8 connected to the rear cylinders 102, 102
Since the open ends of the extension pipes 70 and 90 in the collecting chamber 50, that is, the respective exhaust outlet ends 73 and 93 are constricted 74 and 94, the rear cylinder 10
The pulsation of the exhaust gas from the No. 2,102 improves engine scavenging in the mid-to-low engine speed range, making it possible to increase torque in the mid-to-low engine speed range.

However, according to this, the torque in the engine high speed range is not sufficiently guaranteed, so in the present invention, the extension pipes 70 and 90 are further modified as follows.

First, as shown in FIGS. 6 and 7, small-diameter holes 95 are formed in the curved extension 92 near the outlet end 93 of the right extension tube 90. Two small diameter holes 95 are arranged concentrically in the vertical direction of the curved extension part 92.
A total of 4 pieces 9 are spaced appropriately in the length direction of the extension tube.
5,95 and 96,96 are formed. The total cross-sectional area of the small-diameter holes 95, 96, . . . is set to 40% to 20% of the cross-sectional area of the inner pipe. In other words, an opening is provided on the side surface corresponding to the narrowed outlet, which is approximately the same as when no throttle is provided.

Next, as shown in FIGS. 8 and 9, small diameter holes 75, 75 are formed in the curved extension 72 near the outlet end 73 of the left extension tube 70. Two small diameter holes 75, 75 are formed concentrically in the left and right direction of the curved extension portion 72. Furthermore, as shown in FIG. 10, two similar small-diameter holes 76, 76 are formed concentrically from the upper front to the lower rear in the middle of the upstream curved extension 71 of the extension tube 70. These small diameter holes 75, 76
The total cross-sectional area of ...... is similarly set to 40% to 20% of the cross-sectional area of the extension pipe.

While the engine 10 is running, the left and right extension pipes 70, 90 are connected to the small diameter holes 75, 76, respectively.
Since the exhaust gas from the rear cylinders 102, 102 flows out into the collecting chamber 50 through the exhaust gases 95, 96, .

The formation of the aperture at the outlet end of the extension pipe and the formation of the small-diameter hole work together to achieve an increase in torque in the medium speed range of the engine.

Therefore, with the above configuration, it was possible to realize a smooth increase in torque from the engine speed range to the middle speed range, and to ensure torque in the engine high speed range.

In the embodiments, the present invention has been described as a four-cylinder engine with a V-shaped side surface, but it goes without saying that the present invention can also be applied to a two-cylinder engine or the like as long as the engine has a V-shaped side surface. Further, in the illustrated example, the extension pipe is shown as connecting a plurality of pipes, but it may be configured with one extension pipe.

As is clear from the above description, according to the present invention, in a motorcycle equipped with a lateral V-type engine,
The exhaust pipe connected to the rear cylinder is formed to extend into the collecting chamber, the end of the exhaust pipe inside the collecting chamber is narrowed, and a small diameter hole is formed in the part of the exhaust pipe facing into the collecting chamber. ,
While ensuring the compactness of the collection chamber, it is possible to achieve torque increase in the low engine speed range, guarantee torque in the high speed range, and furthermore achieve torque increase in the medium speed range.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention; Fig. 1 is a side view of a motorcycle, Fig. 2 is a side view of the engine and exhaust pipe portion, and Fig. 3 is an exploded perspective view of the exhaust pipe, collecting chamber, and muffler. Figure 4 is a plan view showing the inside of the collection chamber, Figure 5 is a longitudinal side view of the same,
Figure 6 is a sectional view taken along the line 6-6 in Figure 5, and Figure 7 is a cross-sectional view taken along line 6-6 in Figure 5.
Figure 8 is a cross-sectional view taken along line 7-7 in Figure 5, Figure 9 is a cross-sectional view taken along line 9-9 in Figure 8,
FIG. 0 is a sectional view taken along the line 10-10 in FIG. In the drawing, 1 is a motorcycle, 10 is a horizontal V-type engine, 101, 101 are front cylinders, 30, 40
is its exhaust pipe, 102, 102 is the rear cylinder,
60, 80 are exhaust pipes, 70, 90 are extension pipes, 50
71, 72 and 91, 92 are curved extension portions of the exhaust pipe, 74, 94 are the constricted portions, 7
5, 76 and 95, 96 are the same small diameter holes.

Claims (1)

[Claims] 1 Equipped with a side V-shaped engine, the exhaust pipe connected to the front exhaust port of the front cylinder and the exhaust pipe connected to the rear exhaust port of the rear cylinder are connected to a collective chamber located at the bottom rear of the engine. In a motorcycle, an exhaust pipe connected to an exhaust port on the back surface of the rear cylinder is connected to an extension pipe provided in the collecting chamber, and an outlet end of the extension pipe is formed into a narrow diameter, and a small diameter pipe is formed to communicate between the inside and outside of the pipe. An exhaust pipe for a motorcycle characterized by having a hole formed therein.