Exhaust passage of small watercraft, method of connecting exhaust pipe, and water muffler

1. An exhaust passage configured to discharge an exhaust gas from an engine for driving a propulsion device of a small watercraft, comprising at least:

a first exhaust pipe;

a second exhaust pipe connected to the first exhaust pipe; and

a connecting structure configured to connect the first exhaust pipe and the second exhaust pipe to each other, the connecting structure including:

a first tubular insertion end portion provided at a connecting end portion of the first exhaust pipe so as to protrude toward a connecting end portion of the second exhaust pipe;

a second tubular insertion end portion provided at the connecting end portion of the second exhaust pipe so as to accommodate the first tubular insertion end portion of the first exhaust pipe;

a ring groove formed on an outer peripheral face of the first insertion end portion so as to extend circumferentially over the entire first insertion end portion; and

a seal ring configured to engage in the ring groove such that the seal ring is biased to increase a diameter so as to allow sealing between an outer peripheral face of the seal ring and an inner peripheral face of the second insertion end portion of the second exhaust pipe.

2. The exhaust passage according to claim 1 , wherein the connecting structure further includes a durable sleeve member fitted to an inner peripheral face of the second insertion end portion of the second exhaust pipe so as to be in contact with the outer peripheral face of the seal ring to allow sealing between the sleeve member and the seal ring.

3. The exhaust passage according to claim 2 , wherein the sleeve member is tubular, an end portion of the sleeve member on a connecting end side of the second exhaust pipe has an inner diameter that gradually increases toward the connecting end.

4. The exhaust passage according to claim 1 , wherein at least one of the first exhaust pipe and the second exhaust pipe has a water passage provided in a wall thereof so as to communicate with the ring groove through an elongate hole to allow cooling water to be supplied into the ring groove.

5. The exhaust passage according to claim 1 , wherein the seal ring is made of shape-memory metal.

6. The exhaust passage according to claim 1 , wherein an outer peripheral portion continuous with the first insertion end portion of the first exhaust pipe and located on an opposite side of a connecting end of the first insertion end portion, and an outer peripheral portion of the second insertion end portion of the second exhaust pipe have a substantially equal diameter, and wherein the connecting structure further includes a cover sleeve attached to the first exhaust pipe and the second exhaust pipe so as to substantially cover a connecting portion between the first insertion end portion and the second insertion end portion and a portion adjacent to the connecting portion.

7. The exhaust passage according to claim 6 , wherein the cover sleeve is comprised of a flexible member, and the cover sleeve is fixed to the first and second exhaust pipes at both ends by using bands.

8. An exhaust passage configured to discharge an exhaust gas from an engine for driving a propulsion device of a small watercraft, comprising at least:

a first exhaust pipe;

a second exhaust pipe connected to the first exhaust pipe; and

a connecting structure configured to connect the first exhaust pipe and the second exhaust pipe to each other, the connecting structure including:

a first tubular insertion end portion provided at a connecting end portion of the first exhaust pipe so as to protrude toward a connecting end portion of the second exhaust pipe;

a second tubular insertion end portion provided at the connecting end portion of the second exhaust pipe so as to accommodate the first tubular insertion end portion of the first exhaust pipe;

a ring groove formed on an inner peripheral face of the second insertion end portion so as to extend circumferentially over the entire second insertion end portion; and

a seal ring configured to engage in the ring groove such that the seal ring is biased to reduce a diameter so as to allow sealing between an inner peripheral face of the seal ring and an outer peripheral face of the first insertion end portion of the first exhaust pipe.

9. The exhaust passage according to claim 8 , wherein the connecting structure further includes a durable sleeve member fitted to an outer peripheral face of the first insertion end portion so as to be in contact with the inner peripheral face of the seal ring to allow sealing between the sleeve member and the seal ring.

10. The exhaust passage according to claim 9 , wherein the sleeve member is tubular, and an end portion of the sleeve member on a connecting end side of the first exhaust pipe has an outer diameter that gradually reduces toward the connecting end.

11. The exhaust passage according to claim 8 , wherein at least one of the first exhaust pipe and the second exhaust pipe has a water passage provided in a wall thereof so as to communicate with the ring groove through an elongate hole to allow cooling water to be supplied into the ring groove.

12. The exhaust passage according to claim 8 , wherein the seal ring is made of shape-memory metal.

13. The exhaust passage according to claim 8 , wherein an outer peripheral portion continuous with the first insertion end portion of the first exhaust pipe and located on an opposite side of a connecting end of the first insertion end portion, and an outer peripheral portion of the second insertion end portion of the second exhaust pipe have a substantially equal diameter, and wherein the connecting structure further includes a cover sleeve attached to the first exhaust pipe and the second exhaust pipe so as to substantially cover a connecting portion between the first insertion end portion and the second insertion end portion and a portion adjacent to the connecting portion.

14. The exhaust passage according to claim 13 wherein the cover sleeve is comprised of a flexible member, and the cover sleeve is fixed to the first and second exhaust pipes at both ends by using bands.

15. A method of connecting a first exhaust pipe and a second exhaust pipe, the first exhaust pipe and the second exhaust pipe forming an exhaust passage configured to discharge an exhaust gas from an engine for driving a propulsion device of a small watercraft and having insertion end portions to be connected to each other, the insertion end portion of the first exhaust pipe being configured to be accommodated in the insertion end portion of the second exhaust pipe, and the insertion end portion of the first exhaust pipe and the insertion end portion of the second exhaust pipe being sealed by elastic deformation of a radially and elastically deformable seal ring provided between the insertion end portion of the first exhaust pipe and the insertion end portion of the second exhaust pipe in a radial direction, the method comprising:

forming a ring groove on an outer peripheral face of the insertion end portion of the first exhaust pipe to extend circumferentially over the insertion end portion;

engaging the seal ring in the ring groove and fixing the seal ring to the outer peripheral face of the insertion end portion by using combustible or heat-soluble fixing means so as to inhibit the seal ring from being elastically deformed to increase a diameter;

inserting the insertion end portion of the first exhaust pipe into the insertion end portion of the second exhaust pipe; and

heating the insertion end portions of the first and second exhaust pipes.

16. A method of connecting a first exhaust pipe and a second exhaust pipe, the first exhaust pipe and the second exhaust pipe forming an exhaust passage configured to discharge an exhaust gas from an engine for driving a propulsion device of a small watercraft and having insertion end portions to be connected to each other, the insertion end portion of the first exhaust pipe being configured to be accommodated in the insertion end portion of the second exhaust pipe, and the insertion end portion of the first exhaust pipe and the insertion end portion of the second exhaust pipe being sealed by elastic deformation of a radially and elastically deformable seal ring provided between the insertion end portion of the first exhaust pipe and the insertion end portion of the second exhaust pipe in a radial direction, the method comprising:

forming a ring groove on an inner peripheral face of the insertion end portion of the second exhaust pipe to extend circumferentially over the insertion end portion;

engaging the seal ring in the ring groove and fixing the seal ring to the inner peripheral face of the insertion end portion by using combustible or heat-soluble fixing means so as to inhibit the seal ring from being elastically deformed to reduce a diameter;

inserting the insertion end portion of the first exhaust pipe into the insertion end portion of the second exhaust pipe; and

heating the insertion end portions of the first and second exhaust pipes.

17. An exhaust passage configured to discharge an exhaust gas from an engine for driving a propulsion device of a small watercraft, comprising:

an exhaust pipe partially forming the exhaust passage; and

a water muffler connected to the exhaust pipe;

wherein a downstream end portion of the exhaust pipe is accommodated in the water muffler such that its downstream end is higher than an upstream portion of the exhaust pipe within the water muffler;

wherein the downstream end of the exhaust pipe is located in the vicinity of a center line in a vertical direction of the water muffler;

wherein the exhaust pipe is provided with a waterjacket on an outer peripheral portion of the exhaust pipe, and a water supply port is provided at the downstream end of the exhaust pipe to supply water from the water jacket into the exhaust gas discharged from the downstream end of the exhaust pipe; and

wherein the water jacket is provided so as to cover the exhaust pipe and to extend substantially to a downstream end of the exhaust pipe and has an end wall configured to extend radially outward from the exhaust pipe, and a water supply port is provided on the end wall and configured to supply water to the exhaust gas discharged from the downstream end of the exhaust pipe.

18. The exhaust passage according to claim 17 ,

wherein the water supply port is provided at an upper end portion of the downstream end of the exhaust pipe; and

wherein an end face at the downstream end of the exhaust pipe is inclined to face substantially upward, and the water supply port is formed at an upper end portion of the end wall.

19. The exhaust passage according to claim 17 ,

wherein the water supply port is provided at an upper end portion of the downstream end of the exhaust pipe; and

wherein an end face at the downstream end of the exhaust pipe faces downward and is configured to be vertical or inclined such that a lower end of the exhaust pipe is closer to an upstream side than an upper end of the exhaust pipe, and the water supply port is configured to protrude toward a downstream side more greatly than the lower end of the exhaust pipe.

20. An exhaust passage configured to discharge an exhaust gas from an engine for driving a propulsion device of a small watercraft, comprising:

an exhaust pipe partially forming the exhaust passage; and

a water muffler connected to the exhaust pipe, wherein

a downstream end portion of the exhaust pipe is accommodated in the water muffler such that its downstream end is higher than an upstream portion of the exhaust pipe within the water muffler;

wherein the downstream end of the exhaust pipe is located in the vicinity of a center line in a vertical direction of the water muffler;

wherein the exhaust pipe is provided with a water jacket on an outer peripheral portion of the exhaust pipe, and a water supply port is provided at the downstream end of the exhaust pipe to supply water from the water jacket into the exhaust gas discharged from the downstream end of the exhaust pipe; and

wherein the water jacket is internally provided with a separating wall that defines an upper water jacket and a lower water jacket.

21. The exhaust passage according to claim 20 , wherein a communicating port is provided on the separating wall at the downstream end of the exhaust pipe to allow the lower water jacket and the upper water jacket to communicate with each other.

22. The exhaust passage according to claim 21 , wherein the lower water jacket is provided with a cooling water supply port to supply cooling water into the water jacket, and the upper water jacket is provided with a discharge port to discharge the cooling water from the water jacket.

23. A water muffler in which a downstream end portion of an exhaust pipe partially forming an exhaust passage configured to discharge an exhaust gas from an engine for driving a propulsion device of a small watercraft is accommodated, the water muffler comprising:

an exhaust chamber configured to discharge the exhaust gas inflowing from the engine outside the water muffler, the exhaust chamber being provided with a downwardly recessed concave portion on a bottom face thereof; and

a discharge pipe extending upwardly from the concave portion of the exhaust chamber such that its upper end extends to an outside of the water muffler and its lower end opens into the downwardly recessed concave portion.

24. The water muffler according to claim 23 , wherein the water muffler is configured to have a first chamber, a second chamber, and a third chamber which are arranged in-line in this order from an upstream end side of the exhaust pipe, a downstream end of the exhaust pipe is located within the second chamber, and the exhaust chamber is the third chamber.

25. The water muffler of claim 23 , wherein a step-like cut portion is formed at the lower end of the discharge pipe, and located in the concave portion.

26. An exhaust passage configured to discharge an exhaust gas from an engine for driving a propulsion device of a small watercraft, comprising:

an exhaust pipe partially forming the exhaust passage; and

a water muffler connected to the exhaust pipe;

wherein a downstream end portion of the exhaust pipe is accommodated in the water muffler such that its downstream end is higher than an upstream portion of the exhaust pipe within the water muffler;

wherein the downstream end of the exhaust pipe is located in the vicinity of a center line in a vertical direction of the water muffler;

wherein the exhaust pipe is provided with a water jacket on an outer peripheral portion of the exhaust pipe, and a water supply port is provided at the downstream end of the exhaust pipe to supply water from the water jacket into the exhaust gas discharged from the downstream end of the exhaust pipe;

wherein the water supply port is provided at an upper end portion of the downstream end of the exhaust pipe; and

wherein an end face at the downstream end of the exhaust pipe is configured to be vertical or inclined such that a lower end of the exhaust pipe is closer to an upstream side than an upper end of the exhaust pipe, and the Water supply port is configured to protrude toward a downstream side more greatly than the lower end of the exhaust pipe.