JPH0117609Y2 - - Google Patents

Description

[Detailed Description of the Invention] a. Industrial Application Field The present invention relates to an exhaust system for a multi-cylinder engine.

b. Conventional technology In motorcycles etc. equipped with multi-cylinder engines,
An exhaust system is used that collects exhaust gas discharged from each cylinder into one exhaust pipe and exhausts the exhaust gas.

FIG. 1 shows a conventional exhaust system for a motorcycle equipped with a multi-cylinder engine. This exhaust system is for multi-cylinder engine 1
Exhaust pipes 2 led out from each cylinder are individually connected to an exhaust manifold 3 as shown in FIG. However, in such an exhaust system, the rear end portions of the exhaust pipes 2 are individually connected to the exhaust manifold 3 by welding, so the exhaust manifolds 3 must be provided with separate connection holes. Furthermore, since each exhaust pipe 2 must be welded all around, work efficiency is reduced.

Therefore, as shown in Fig. 3, the rear ends of each exhaust pipe 2 are formed so that the cross section is fan-shaped so that the rear ends of the exhaust pipes 2 are assembled to form one cylinder. However, a method is conceivable in which these rear end portions are assembled into one cylinder and connected to the exhaust manifold 3. In this way, if the exhaust pipe 2 is made into a single cylindrical shape,
The number of holes 3a formed in the exhaust manifold 3 is 1
It is better to have only one piece, which improves work efficiency. (Related prior art includes Japanese Utility Model Publication No. 46-31288.) c. Problems to be solved by the invention However, by forming the rear end of the exhaust pipe 2 into a fan shape, the flow of exhaust gas changes. This was a malfunction that caused a drop in output.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide an exhaust system for a multi-cylinder engine that can improve the workability of assembly work without causing a decrease in output.

d. Means for Solving the Problems In order to solve the above problems, the present invention provides a multi-cylinder engine in which exhaust pipes led out from each cylinder of a multi-cylinder engine are assembled into a single cylinder and connected to an exhaust manifold. In the exhaust system, the connection part of the exhaust pipe is internally arranged in a fan-shaped cylinder body having a shape in which a cylinder is divided into four parts in the radial direction,
These fan-shaped cylinders are combined into one cylinder and connected to the exhaust manifold.

e Function The exhaust pipe combines fan-shaped cylinders provided on the outer peripheral surface into one pipe and connects it to the exhaust manifold.

Exhaust gas exhausted from the exhaust pipe passes through the cylindrical pipe without being hindered in its flow and is introduced into the exhaust manifold.

f Embodiments Hereinafter, the present invention will be described in detail with reference to illustrated embodiments.

In FIGS. 4 to 6, 10 is a cylindrical exhaust pipe led out from each cylinder of a multi-cylinder engine (not shown).

The exhaust pipe 10 has a cylindrical body 12 having a fan-shaped cross section attached to the outer peripheral surface of the rear end 11, and the fan-shaped cylindrical bodies 12 are combined with each other and the contact end surfaces are welded to form a single cylindrical body. .

These assembled fan-shaped cylinders 12 are fitted as a single cylinder into a connection hole 14 formed in the exhaust manifold 13, and are connected to the exhaust manifold 13 by welding along the periphery of the connection hole 14. The exhaust malfold 13 is connected to a muffler 16 via an exhaust pipe 15.

According to the exhaust system for the multi-cylinder engine described above, an exhaust pipe 10 and an exhaust manifold 1
3, the assembled fan-shaped cylinders 12 are used to weld to the peripheral edge of the connection hole 14 of the exhaust manifold 13. The fan-shaped cylindrical body 12 of the exhaust pipe 10 and the exhaust manifold 13 can be connected only by welding along the periphery of the connection hole 14 of the exhaust manifold 13.

On the other hand, since the exhaust pipe 10 remains a cylindrical pipe, exhaust gas passes through the cylindrical pipe from the engine to the exhaust manifold 13. Therefore, it is possible to prevent a decrease in output due to mutual interference between exhaust gases discharged from different cylinders.

g. Effects of the invention According to the exhaust system for a multi-cylinder engine according to the invention, the exhaust pipes of a multi-cylinder engine are assembled into one cylinder and connected to an exhaust manifold. In the device, the connecting portion of the exhaust pipe is internally arranged in a fan-shaped cylinder having a shape in which a cylinder is divided into four parts in the radial direction, and these fan-shaped cylinders are combined into one cylinder to form the exhaust manifold. Since the exhaust pipe has a perfectly circular cross section all the way to the rear end, the negative effect on output performance can be further reduced. Furthermore, since the sector-shaped cylinders can be combined into one cylinder, connection with the exhaust manifold is easy.

[Brief explanation of the drawing]

1 to 3 show exhaust systems for conventional multi-cylinder engines, FIG. 1 is a conceptual diagram showing the exhaust system for multi-cylinder engines mounted on motorcycles, and FIG. - A sectional view and FIG. 3 are perspective views showing an exhaust pipe whose rear end portion is formed into a sector-shaped cross section. FIG. 4 is a conceptual diagram showing an exhaust system for a multi-cylinder engine according to an embodiment of the present invention;
The figure is a perspective view showing the connecting part between the exhaust pipe and the exhaust manifold in Fig. 4, Fig. 6 a and b show the exhaust pipe in Fig. 5, Fig. 6 a is a longitudinal sectional view, and Fig. 6 b is FIG. 6 is a sectional view taken along line A-A in FIG. 6a; DESCRIPTION OF SYMBOLS 10... Exhaust pipe, 11... Rear end part, 12... Fan-shaped cylinder, 13... Exhaust manifold.

Claims (1)

[Scope of utility model registration request] In an exhaust system for a multi-cylinder engine in which exhaust pipes led out from each cylinder of a multi-cylinder engine are assembled into one cylinder and connected to an exhaust manifold, the connecting part of the exhaust pipe is divided into four parts in the radial direction of the cylinder. What is claimed is: 1. An exhaust system for a multi-cylinder engine, characterized in that the fan-shaped cylinders are installed inside fan-shaped cylinders, and these fan-shaped cylinders are combined into one cylinder and connected to the exhaust manifold.