Claims
- 1. In an exhaust system for an outboard motor having an engine with an exhaust outlet, an expansion chamber, means including an exhaust pipe for delivering exhaust gases from said exhaust outlet to said expansion chamber, an exhaust gas discharge normally disposed below the surface of the water when said motor is propelling a watercraft, and means for delivering exhaust gases from said expansion chamber to said exhaust gas discharge, the improvement comprising said exhaust pipe extending through a wall which divides said expansion chamber into two parts, said exhaust pipe extending though said first part and terminating in said second part, and an annular opening in said wall defined by an extending flange encircling said exhaust pipe and through which said exhaust pipe passes and which communicates said parts with each other and which forms a tuning neck.
- 2. In an exhaust system as set forth in claim 1 wherein the flange is an upstanding flange.
- 3. In an exhaust system as set forth in claim 1 wherein the first part has restricted communication with an above the water slow speed exhaust gas discharge for discharging exhaust gases directly to the atmosphere under slow speed running.
- 4. In an exhaust system as set forth in claim 3 wherein the restricted communication of the first part with the slow speed exhaust gas discharge is through a second expansion chamber.
- 5. In an exhaust system as set forth in claim 4 wherein there is a further third expansion chamber interposed between the second expansion chamber and the slow speed exhaust gas discharge.
- 6. In an exhaust system for an outboard motor having an engine with an exhaust outlet, a first expansion chamber, means for communicating exhaust gases from said exhaust outlet with said first expansion chamber, a high speed exhaust gas discharge normally disposed below the surface of the water when said motor is propelling a watercraft at speed, and means for delivering exhaust gases from said first expansion chamber to said high speed exhaust gas discharge, the improvement comprising a second expansion chamber communicating with said first expansion chamber through a tuned conduit and a slow speed exhaust gas discharge communicating said second expansion chamber with the atmosphere above the water level, the communication of said second expansion chamber with the atmosphere being substantially restricted relative to the communication between said first expansion chamber and said second expansion chamber for reducing the discharge of exhaust gases to the atmosphere through said slow speed exhaust gas discharge at high speeds and for causing said tuned conduit and said second expansion chamber to function as a Hemholtz resonator during high speed exhaust conditions by precluding any substantial exhaust gas discharge from said second expansion chamber to the atmosphere through said slow speed exhaust gas discharge.
- 7. In an exhaust system as set forth in claim 6 further including a third expansion chamber communicating with the second expansion chamber and through which the exhaust gases flow to the slow speed exhaust gas discharge.
- 8. In an exhaust system as set forth in claim 7 wherein the second and third expansion chambers have restricted communication with each other.
- 9. In an exhaust system as set forth in claim 6 wherein the first expansion chamber and the second expansion chamber are positioned in vertically spaced relationship and the means for delivering the exhaust gases to the first expansion chamber comprises an exhaust pipe extending through the second expansion chamber and terminating in the first expansion chamber.
- 10. In an exhaust system as set forth in claim 9 wherein a wall divides the first expansion chamber from the second expansion chamber and the wall has an opening through which the exhaust pipe passes, said opening being defined by an extending flange which forms the tuned conduit.
- 11. In an exhaust system as set forth in claim 10 further including a third expansion chamber communicating with the second expansion chamber and through which the exhaust gases flow to the slow speed exhaust gas discharge.
- 12. In an exhaust system as set forth in claim 11 wherein the second and third expansion chambers have restricted communication with each other.
- 13. An exhaust system for an outboard motor comprising a power head having an internal combustion engine with an exhaust outlet, a drive shaft housing depending from said power head and defining a cavity, a lower unit depending from said drive shaft housing and defining an exhaust discharge, a plurality of wall members extending transversely across said drive shaft housing cavity for dividing said cavity into at least three vertically spaced chambers at least one of which forms an expansion chamber and for reinforcing said drive shaft housing, means for communicating said chambers with each other, means for delivering exhaust gases from said exhaust outlet to one of said chambers comprising an exhaust pipe extending through one of said walls, said exhaust pipe extending through said expansion chamber and terminating in another of said chambers, an annular opening in said wall defining an extending flange encircling said exhaust pipe and through which said exhaust pipe passes to form a tuning neck and which communicates said other chamber with said expansion chamber, means for delivering exhaust gases from one of said chamber to said exhaust discharge and an above the water slow speed exhaust gas discharge extending through said drive shaft housing and in communication with one of the chambers.
- 14. In an exhaust system as set forth in claim 13 wherein the flange is an upstanding flange.
- 15. In an exhaust system as set forth in claim 13 wherein the first expansion chamber has restricted communication with the above the water slow speed exhaust gas discharge for discharging exhaust gases directly to the atmosphere under slow speed running.
- 16. In an exhaust system as set forth in claim 15 wherein the restricted communication of the first expansion chamber with the slow speed exhaust gas discharge is through a second expansion chamber.
Priority Claims (1)
Number |
Date |
Country |
Kind |
57-68908 |
Apr 1982 |
JPX |
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Parent Case Info
This application is a continuation of application Ser. No. 486,406, filed Apr. 19, 1983, now abandoned.
US Referenced Citations (5)
Foreign Referenced Citations (1)
Number |
Date |
Country |
119908 |
Sep 1980 |
JPX |
Continuations (1)
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Number |
Date |
Country |
Parent |
486406 |
Apr 1983 |
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