JPH03264717A - Coupling device of exhaust pipe for engine - Google Patents

Abstract

PURPOSE:To insure coupling and simplify the working by outward fitting a coupling cylinder fixedly secured on the taper end part of an exhaust pipe to the cylindrical part of a connecting cylinder, and forming a series of inner circumferential taper faces with the inner circumferential taper face of the exhaust pipe and the inner circumferential taper face of the connecting cylinder. CONSTITUTION:The coupling device 15 of an exhaust pipe 5 is provided with a connecting cylinder 16 fitting to the exhaust port 2 of a cylinder head 1 through a gasket 3. On the inner circumferential face of the connecting cylinder 16, a taper hole 17 continuing to the inner circumferential taper face 5a of the exhaust pipe 5 is drilled. Further, the outer circumferential face of the projecting part of the connecting cylinder 16 from the cylinder head 1 is formed into a straight cylindrical part 18 having a uniform diameter. Meanwhile, a coupling cylinder 20 having a connecting hole 19 closely fitting to the cylindrical part 18 is fixedly secured on the taper end part of the exhaust pipe 5 by welding 21 and the like. By outward fitting the coupling cylinder 20 to the cylindrical part 18, the inner circumferential face of the taper hole 17 is continued to the taper inner circumferential face 5a to form a continuous taper inner circumferential face.

Description

[Detailed description of the invention] [Purpose of the invention] (Industrial application field) The present invention relates to an engine exhaust pipe connection device.

(Prior Art) The exhaust pipe of a motorcycle equipped with a 4-cycle engine has conventionally been a straight pipe with a uniform diameter, and the connection to the exhaust port of the engine is through the exhaust port 2 of the cylinder head 1 as shown in FIG.
The end of the exhaust pipe 5 is inserted into the outer periphery of the protruding portion of the connecting pipe 4 fitted with the gasket 3 interposed therebetween until it abuts against the flange 6 of the connecting pipe 4, and is fitted to the flange 7 of the exhaust pipe 5. A bolt 8 to be passed through is tightened to the cylinder head 1, and a spring 11 is tensioned between the head 9 of the bolt 8 and a hook IO provided on the outer periphery of the exhaust pipe 5, so that the exhaust pipe 5 is held. ing.

In addition, by attaching a double inner and outer connecting tube to the exhaust port 2, and making the outer circumferential surface of this inner tube tapered and inserting the end of the exhaust pipe 5 between the inner and outer tubes, the exhaust pipe 5 is connected by being pressed into contact with the taper. There is a method (Japanese Utility Model Application Publication No. 125314/1983) in which this is done.

Motorcycles with these structures have the advantage of being resistant to vibration, easy to dismantle, and therefore easy to maintain, and are often used in motorcycles with four-stroke engines, especially racing machines.

However, in recent years, in this type of four-stroke engine, there has been a trend to make the connecting end of the exhaust pipe 5 tapered to improve the muffler effect in order to improve engine output. When the exhaust pipe is tapered in this way, the structure of the connecting part also needs to be adapted to the connecting structure. Therefore, as shown in FIG. The exhaust pipe 5 has a tapered hole 12, and a tapered outer circumferential surface 13 of the exhaust pipe 5 is press-fitted onto the inner circumferential surface of the tapered hole 12 for connection.

(Problem to be Solved by the Invention) However, in the connection structure shown in FIG. It is not easy to form the end of the exhaust pipe 5 into a tapered shape with high precision, and there is a problem in that it is very difficult to appropriately manage this fitting.

In view of the above-mentioned points, the present invention provides an engine exhaust pipe connecting device in which the fitting of the fitting portion with the connecting tube can be easily managed even if the exhaust pipe is tapered.

[Structure of the invention]

(Means for Solving the Problems) As a means for solving the problems of the prior art described above, the present invention provides an engine exhaust pipe connection device having a structure in which a tapered exhaust pipe is inserted into and connected to an engine exhaust port. , the inner circumferential surface of the connecting tube fixed to the exhaust port is formed into a tapered hole having a taper that is continuous with the tapered inner circumferential surface of the tapered end of the exhaust pipe, and the outer circumference of the connecting tube is formed into a straight cylindrical part. and fixing to the tapered end of the exhaust pipe a connecting cylinder having a cylindrical connecting hole with an inner diameter that fits externally into the cylindrical part of the connecting cylinder, and fitting the connecting cylinder externally into the cylindrical part of the connecting cylinder. Accordingly, the tapered inner circumferential surface of the connecting cylinder and the inner circumferential surface of the exhaust pipe form a continuous tapered inner circumferential surface.

(Function) When connecting exhaust pipes, if the connecting cylinder fixed to the tapered end is inserted so as to fit into the cylindrical part of the connecting cylinder, the inner peripheral surface of the tapered hole of the connecting cylinder and the taper of the exhaust pipe will be connected. The inner curved surface forms a series of tapered inner circumferential surfaces. The connection between the connecting tube and the exhaust pipe is not a tapered fit but a straight cylindrical fit, which provides excellent vibration resistance and facilitates maintenance and dimensional control.

(Example) Embodiments of the present invention will be described below with reference to the accompanying drawings.

In explaining the engine exhaust pipe coupling device of the present invention, the same reference numerals are given to the same members as in the conventional exhaust pipe coupling device.

FIG. 2 shows an example in which the exhaust pipe 5 is equipped with an exhaust pipe connecting device 15 of the present invention. Specifically, as shown in FIG. The connecting tube 16 has a connecting tube 16 that is fitted through the connecting tube 16, and the connecting tube 16 has a tapered hole 17 whose inner circumferential surface is continuous with the tapered inner circumferential surface 5a of the tapered end of the exhaust pipe 15. The outer peripheral surface of the protruding portion protruding from the cylinder head 1 is a straight cylindrical portion 18 having a uniform diameter.

On the other hand, to the tapered end of the exhaust pipe 5, a connecting tube 20 having a connecting hole 19 having an inner diameter that fits tightly onto the cylindrical portion 18 of the connecting tube 16 is fixed by welding 21 or the like.

Therefore, when the connecting tube 20 of the exhaust pipe 5 is inserted into the cylindrical portion 18 of the connecting tube 16 so as to fit externally, the inner circumferential surface of the tapered hole 17 of the connecting tube 16 and the tapered inner circumferential surface 5a of the exhaust pipe 5 are aligned. A continuous tapered inner circumferential surface is formed.

Since the other configurations are the same as the conventional example shown in FIG. 4, the same reference numerals as in FIG. 4 are given, and the explanation thereof will be omitted.

Since the present invention has the above-described configuration, the connection of the exhaust pipe 5 is to connect the connecting hole 19 having a straight inner circumference of the connecting cylinder 2o fixed to the exhaust pipe 5 to the cylindrical part 18 having a straight outer surface of the connecting cylinder 16. Since it is only necessary to insert and fit, the fitting connection can be ensured in the same way as in the case of a conventional straight exhaust pipe, and the cylindrical portion 18 and the connection hole 91 that make up the connecting part are both cylindrical. Therefore, high precision can be achieved through machining, making management easier. In addition to being able to maintain a proper fit even when subjected to severe vibrations, such as those found on racing machines, the structure maintains the same ease of maintenance even when disassembled as with conventional straight exhaust pipes.

〔Effect of the invention〕

In the engine exhaust pipe connection device according to the present invention,
Even when connecting exhaust pipes that have a tapered shape, the connection to the cylinder head side is a simple fitting of cylindrical shapes, so the fitting part is easy to manufacture, can be processed with high precision, and can be properly processed. It is possible to obtain a well-fitted state. In addition, since the inner circumferential surface of the connecting tube also constitutes a part of the tapered inner circumferential surface of the exhaust pipe, the effect of making the exhaust pipe into a tapered shape is not impaired, and the tapered hole of the connecting tube can be machined. It has the advantage of being able to freely adapt to the taper angle of the exhaust pipe.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of an engine exhaust pipe connecting device according to the present invention, FIG. 2 is a perspective view showing an exhaust pipe equipped with the engine exhaust pipe connecting device according to the present invention, and FIG. Sectional view showing the conventional straight exhaust pipe connection structure, No. 4
The figure is a sectional view showing a conventional tapered exhaust pipe connection structure. 1... Cylinder head, 2... Exhaust port, 4.14.
...Connecting tube, 5...Exhaust pipe, 5a...Tapered inner peripheral surface, 15...Exhaust pipe coupling device, 16...Connecting tube, 1
7...Tapered hole, 18...Cylindrical part, 19...Connection hole, 20...Connecting cylinder. Figure 11Figure 3Figure 2rlli 4JXI

Claims (1)

[Claims] In an engine exhaust pipe connection device having a structure in which a tapered exhaust pipe is inserted and connected to an engine exhaust port,
The inner circumferential surface of the connecting tube fixed to the exhaust port is formed into a tapered hole that is continuous with the tapered inner circumferential surface of the tapered end of the exhaust pipe, and the outer circumference of the connecting tube is formed into a straight cylindrical part. By fixing to the tapered end of the exhaust pipe a connecting tube having a cylindrical connecting hole with an inner diameter that fits externally into the cylindrical portion of the connecting tube, and fitting the connecting tube externally into the cylindrical portion of the connecting tube. An exhaust pipe coupling device for an engine, characterized in that the tapered hole of the connecting tube and the inner circumferential surface of the exhaust pipe form a continuous tapered inner circumferential surface.