JP2717287B2 - Engine exhaust system - Google Patents

Description

Description: Object of the Invention (Field of Industrial Application) The present invention relates to an exhaust system for an engine, and in particular, to an exhaust system for an engine mounted on, for example, a small watercraft that needs to cool a muffler. Related to the device.

(Prior Art) In general, as shown in FIG. 3, in a small personal watercraft, exhaust gas from an engine 2 mounted on a hull 1 is guided to a muffler 4 and a muffler 5 through an exhaust pipe 3 and discharged. It is supposed to. The muffler 4 and the muffler 5 reduce exhaust noise.

As shown in FIG. 3, a part of the engine cooling water passes through the water jacket 6 of the exhaust pipe 3 and is injected into the muffler 4 from the small hole 7. This allows
The exhaust pipe 3 and the muffler 4 can be cooled, and the water stored in the muffler 4 further reduces exhaust noise.

In addition, a device described in Japanese Utility Model Publication No. 57-7769 (hereinafter referred to as the second
4, the muffler 8 is divided into two in the longitudinal direction, and these muffler elements 8A and 8B are connected by an elastic body 9, as shown in FIG. Symbol 10 is
A band for fixing the elastic body 9. Muffler element 8B
Is further elastically supported by the engine 12 by the mount rubber 11.

In the second conventional example, similarly to the conventional examples shown in FIGS. 2 and 3 (hereinafter, referred to as a first conventional example), a part of the engine cooling water is guided into the muffler 8 through an exhaust pipe. The muffler 8 is stored in the muffler 8 so that the muffler 8 is cooled and exhaust noise is reduced. Further, in the second conventional example, it is considered that the vibration transmitted from the engine is absorbed by the elastic body 9 and the mount rubber 11, and the muffler 8 is not damaged by the vibration.

(Problems to be Solved by the Invention) However, in the first and second conventional examples, since a part of the cooling water of the engine 2 is stored in the mufflers 4 and 8, the internal volume of the muffler also serving as the expansion chamber is reduced. The engine output may decrease.

Further, since the engine cooling water is stored in the mufflers 4, 8, when the hull 1 is tilted or inverted, the engine cooling water stored in the mufflers 4, 8 flows back into the cylinders of the engines 2, 12. Sometimes. A similar phenomenon may be caused by a change in exhaust pressure.

Further, particularly in the first conventional example, the vibration of the engine 2 is transmitted to the muffler 4 via the exhaust pipe 3, and the muffler 4 may be damaged by the vibration.

The present invention has been made in consideration of the above circumstances, and can appropriately cool the muffler, prevent the cooling water in the muffler from flowing back into the cylinder, and prevent a decrease in engine output. It is another object of the present invention to provide an engine exhaust device that can prevent damage due to vibration of a muffler.

[Configuration of the invention]

(Means for Solving the Problems) According to the present invention, in an exhaust system for an engine in which a muffler is connected to an exhaust pipe of the engine, the muffler is connected to the exhaust pipe via a joint member, and the muffler is connected to the inside of the muffler. A muffler water jacket is formed which has a pipe and a muffler outer pipe, and which is surrounded by these muffler inner and outer pipes and communicates with a water jacket of the exhaust pipe. The muffler outer tube is elastically supported via an elastic member while being supported.

(Operation) Therefore, according to the engine exhaust device of the present invention, the muffler water jacket is formed on the muffler,
Since a part of the engine cooling water is guided into the muffler water jacket via the water jacket of the exhaust pipe, the muffler can be suitably cooled.

Further, since the muffler water jacket is not communicated with the cylinder of the engine, the engine cooling water stored in the muffler water jacket does not flow back to the cylinder. Moreover, the inside of the muffler inner tube is communicated with the cylinder through the exhaust pipe, and the engine cooling water is not stored in the muffler inner tube, so that the volume in the muffler inner tube does not substantially decrease, and as a result, the engine output does not decrease. .

Furthermore, since the muffler inner tube is supported by a spherical pair via a joint member and the muffler outer tube is elastically supported via a joint member and an elastic member, the vibration of the exhaust pipe is absorbed by the joint between the muffler and the joint member. And muffler vibration can be reduced. As a result, damage due to vibration of the muffler can be prevented.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view showing a main part of a muffler to which an embodiment of an engine exhaust device according to the present invention is applied.

An exhaust pipe 21 is connected to an engine (not shown) mounted on the small watercraft. A muffler 23 and a muffler (not shown) are sequentially connected to the exhaust pipe 21 via a joint member 22 to configure an exhaust device of the engine.

A water jacket 24 is formed on the exhaust pipe 21. A part of the engine cooling water is guided into the water jacket 24, and the exhaust pipe 21 is cooled well.

The muffler 23 has a muffler inner tube 25 and a muffler outer tube 26.
Is a double-pipe structure. These muffler inner and outer tubes 2
A muffler water jacket 27 is formed surrounded by 5,26. In addition, a curved spherical joint 28 formed of a part of a spherical surface is formed at the distal end of the muffler inner tube 25.

Now, the joint member 22 is the joint flange 2
9. It has a joint inner tube 30 and a joint outer tube 31, each of which is made of, for example, stainless steel.

The joint flange 29 is formed in a ring shape. The joint flange 29 is connected to the exhaust pipe 21 via a gasket 32 by a bolt 33. Further, a plurality of passages 34 are formed in the joint flange 29 in the circumferential direction of the joint flange 29. The passage 34 communicates the water jacket 24 of the exhaust pipe 21 and the muffler water jacket 27 via the small hole 35 of the gasket 32. A plurality of small holes 35 are also formed corresponding to the passages 34.

Therefore, the engine cooling water in the water jacket 24 of the exhaust pipe 21 is guided into the muffler water jacket 27 via the passage 34 and the small hole 35. The engine cooling water in the muffler water jacket 27 is then guided to the muffler together with the exhaust gas, and is discharged out of the boat.

The joint inner pipe 30 is fixed to the inner peripheral part of the joint flange 29 in an upright state, and a spherical joint part is attached to a tip end thereof.
36 is formed. The spherical joint portion 36 is formed on a curved surface composed of a part of a spherical surface, similarly to the spherical joint portion 28 of the muffler inner tube 25, and the spherical joint portion 28 is supported in the spherical joint portion 36 in a spherical pair. . Therefore,
The exhaust pipe 21 is connected to the muffler inner pipe 25 by the spherical joints 28 and 36, and the exhaust gas in the exhaust pipe 21 is guided to the muffler inner pipe 25.

Meanwhile, an upper bracket 37 is fastened to the exhaust pipe 21 together with a bolt 33, and a lower bracket 38 is fixed to the muffler outer pipe 26. A spring 39 is interposed between the upper and lower brackets 37 and 38. The muffler 23 is supported by the exhaust pipe 21 and the joint member 22 by the tensile force of the spring 39, and the seal between the spherical joints 28 and 36 is sufficiently provided. Therefore, the exhaust gas flowing through the joint inner pipe 30 and the muffler inner pipe 25 does not leak into the muffler water jacket 27 via the spherical joints 28 and 36, and the engine cooling water in the muffler water jacket 27 does not leak. It does not flow into the joint inner tube 30 and the muffler inner tube 25. The number of the springs 39 is, for example, two or three in the circumferential direction of the muffler 23.

The joint outer tube 31 is fixed to the outer peripheral portion of the joint flange 29 in an upright state. This joint outer tube 31
A heat-resistant rubber hose 40 as an elastic member is mounted between the distal end of the muffler outer tube 26 and the muffler outer tube 26. This heat resistant rubber hose 40
Is fixed to the joint outer tube 31 and the muffler outer tube 26 by a band 41.

Therefore, according to the above embodiment, even if the exhaust pipe 21 vibrates due to the vibration of the engine, even if the exhaust pipe 21 vibrates,
25 moves spherically with respect to the joint inner tube 36 by the spherical joints 28 and 36, and since the muffler outer tube 26 is connected to the muffler outer tube 26 via a heat-resistant rubber hose 40, the muffler 23 is connected to the exhaust pipe 21. Vibration is not transmitted. Since the vibration of the exhaust pipe 21 is absorbed by the spherical joints 28 and 36 and the heat-resistant rubber hose 40, the vibration of the exhaust pipe 21 causes the muffler.
23 can be prevented from being damaged.

In addition, part of the engine cooling water is exhaust pipe
Since the muffler 23 is guided into the muffler water jacket 27 through the water jacket 24 and the passage 34 of the joint member 22, the muffler 23 can be cooled appropriately.

Further, the muffler water jacket 27 is connected to the passage 34.
Exhaust pipe 21 through water jacket 24
And the engine cooling water stored in the muffler water jacket 27 flows back to the cylinder even if the boat tilts, reverses, or changes in exhaust pressure because it is not connected to the engine cylinder. Can be prevented.

Further, the cylinder of the engine is communicated with the muffler inner tube 25, and since the engine cooling water is not stored in the muffler inner tube 25, the muffler 23 also serves as an expansion chamber.
The internal capacity of the muffler inner tube 25 does not change, and it is possible to prevent the output performance of the engine from lowering.

In the above-described embodiment, the description has been given of the case where the exhaust device of the engine is applied to the engine mounted on the small watercraft. However, the present invention can be similarly applied to an engine that needs to cool the muffler.

〔The invention's effect〕

As described above, according to the engine exhaust device of the present invention, the muffler is connected to the exhaust pipe through the joint member, and the muffler has the muffler inner tube and the muffler outer tube. A muffler water jacket that is surrounded by inner and outer pipes and communicates with a water jacket of the exhaust pipe is formed. Resiliently supported, part of the engine cooling water is guided into the muffler water jacket to cool the muffler satisfactorily. Can be prevented, and the above-mentioned spherical pair support and elastic support prevent damage due to muffler vibration. That.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a main part of a muffler to which an embodiment of an engine exhaust device according to the present invention is applied, FIG. 2 is a side view showing a small watercraft with a part cut away, FIG. FIG. 4 is a side view showing a main part of an engine exhaust system of a first conventional example with a part cut away, and FIG. It is. 21 ... exhaust pipe, 22 ... joint member, 23 ... muffler, 24 ... water jacket, 25 ... muffler inner tube, 26 ...
Muffler outer tube, 27… Muffler water jacket, 28,36…
Spherical joint, 29 joint flange, 30 joint inner tube, 31 joint outer tube, 34 passage, 40 heat resistant rubber hose.

Claims (1)

(57) [Claims] 1. An exhaust system for an engine in which a muffler is connected to an exhaust pipe of the engine, wherein the muffler is connected to the exhaust pipe via a joint member, and the muffler has an inner pipe for the muffler and an outer pipe for the muffler. A muffler water jacket is formed which is surrounded by the muffler inner and outer pipes and communicates with a water jacket of the exhaust pipe.The joint member supports the muffler inner pipe with a spherical pair, and the muffler outer pipe An exhaust device for an engine, wherein the device is elastically supported via an elastic member.