Exhaust system for outboard motor

• US 6,783,413 B2
• Filed: 05/17/2001
• Issued: 08/31/2004
• Est. Priority Date: 05/18/2000
• Status: Expired due to Fees

• Current Assignee: Yamaha Marine Kabushiki Kaisha
• Original Assignee: Yamaha Marine Kabushiki Kaisha
• Inventors: Nakata, Jun, Shibata, Yasuhiko
• Primary Examiner(s): Wright, Andrew
• Application Number:
  US09/860,989
• Publication Number:
  US 20010044245A1
• Time in Patent Office: 1,202 Days
• Field of Search: 440/88, 440/89, 440/89.R, 440/89.G
• US Class Current: 440/89.00R
• CPC Class Codes: B63H 20/245 Exhaust gas outlets B63H20/26 takes precedence
• CPC Class Codes: B63H 20/285 Cooling-water intakes
• CPC Class Codes: F01N 13/004 specially adapted for marine propulsion, i.e. for receiving simultaneously engine exhaust gases and engine cooling water for submerged exhausting F01N13/12; treating exhaust by using liquids F01N3/04
• CPC Class Codes: F01N 13/12 specially adapted for submerged exhausting
• CPC Class Codes: F01N 2590/021 for outboard engines
• CPC Class Codes: F01P 3/202 for outboard marine engines
• CPC Class Codes: F02B 2075/027 four
• CPC Class Codes: F02B 2075/1816 four
• CPC Class Codes: F02B 61/045 for outboard marine engines
• CPC Class Codes: F02B 75/20 with cylinders all in one line

Abstract

An exhaust system for an outboard motor includes an internal combustion engine. An intermediate member supports the engine. A housing unit depends from the intermediate member. An exhaust system guides exhaust gases from the engine. The exhaust system includes a main exhaust passage and an idle exhaust passage. The main exhaust passage discharges the exhaust gases that are produced above idle to the body of water through the housing unit. The idle exhaust passage discharges the exhaust gases that are produced during idle to the atmosphere. The intermediate member defines a portion of the main exhaust passage and a portion of the idle exhaust passage. The intermediate member forms a recessed area in the main exhaust passage portion. The idle exhaust passage communicates with the main exhaust passage portion at the recessed area.

Claims

1. An outboard motor comprising an internal combustion engine, an intermediate member supporting the engine, a housing unit supporting the intermediate member, and an exhaust system configured to guide exhaust gases from the engine, the exhaust system including a main exhaust passage and an idle exhaust passage, the main exhaust passage configured to discharge exhaust gases produced at engine speeds above idle to the body of water through the housing unit, the idle exhaust passage configured to discharge exhaust gases produced at idle engine speeds to the atmosphere, the intermediate member defining at least a portion of the main exhaust passage and a portion of the idle exhaust passage, the intermediate member forming a recessed area in the main exhaust passage portion, the idle exhaust passage having a port that opens at the recessed area, the recessed area being larger than the port and being formed such that a step, which is defined between a portion of the main exhaust passage and a portion of the recessed area, includes an edge that extends in an upward direction.

2. The outboard motor as set forth in claim 1, wherein the recessed area is formed at generally downstream part of the main exhaust passage portion defined in the intermediate member.

3. The outboard motor as set forth in claim 2, wherein the port is positioned closer to the housing unit than to the engine.

4. The outboard motor as set forth in claim 1, wherein the main exhaust passage portion defined in the intermediate member has a configuration that is a combination of a right trapezoidal pillar or column and an inverted trapezoidal pillar or column.

5. The outboard motor as set forth in claim 4, wherein the port is positioned on a side of either one of the right or inverted trapezoidal pillars or columns that is located at downstream part of the main exhaust passage portion.

6. The outboard motor as set forth in claim 5, wherein the port is positioned closer to the housing unit than to the engine.

7. The outboard motor as set forth in claim 1, wherein the exhaust system includes an exhaust conduit depending from the intermediate member, the exhaust conduit communicates with the main exhaust passage portion of the intermediate member to define a further portion of the main exhaust passage.

8. An outboard motor comprising an internal combustion engine, an intermediate member supporting the engine, a housing unit supporting the intermediate member, and an exhaust system configured to guide exhaust gases from the engine, the exhaust system including a main exhaust passage and an idle exhaust passage, the main exhaust passage configured to discharge exhaust gases produced at engine speeds above idle to the body of water through the housing unit, the idle exhaust passage configured to discharge exhaust gases produced at idle engine speeds to the atmosphere, the intermediate member defining at least a portion of the main exhaust passage and a portion of the idle exhaust passage, the intermediate member forming a recessed area in the main exhaust passage portion, the idle exhaust passage having a port that opens at the recessed area, the recessed area being larger than the port, the idle exhaust passage portion extending from the main exhaust passage portion at an acute angle relative to a direction of exhaust gas flow in the main exhaust passage portion.

9. An outboard motor comprising an internal combustion engine, an intermediate member supporting the engine, a housing unit supporting the intermediate member, and an exhaust system configured to guide exhaust gases from the engine, the exhaust system including a main exhaust passage and an idle exhaust passage, the main exhaust passage configured to discharge exhaust gases produced at engine speeds above idle to the body of water through the housing unit, the idle exhaust passage configured to discharge exhaust gases produced at idle engine speeds to the atmosphere, the intermediate member defining at least a portion of the main exhaust passage and a portion of the idle exhaust passage, the intermediate member forming a recessed area in the main exhaust passage portion, the idle exhaust passage communicating with the main exhaust passage portion at the recessed area, the idle exhaust passage portion extending from the main exhaust passage portion at an acute angle relative to a direction of exhaust gas flow in the main exhaust passage portion.

10. An outboard motor comprising an internal combustion engine, an intermediate member supporting the engine, a housing unit supporting the intermediate member, an exhaust system configured to guide exhaust gases from the engine, the exhaust system including a main exhaust passage and an idle exhaust passage, the main exhaust passage configured to discharge exhaust gases produced at engine speeds above idle to the body of water through the housing unit, the idle exhaust passage configured to discharge exhaust gases produced at idle engine speeds to the atmosphere, the intermediate member defining at least a portion of the main exhaust passage and a portion of the idle exhaust passage, the intermediate member forming a recessed area in the main exhaust passage portion, the idle exhaust passage communicating with the main exhaust passage portion at the recessed area, a cooling system arranged to cool at least part of the exhaust system extending within the housing unit, and a gasket interposed between the intermediate member and the housing unit, the intermediate member defining a second portion of the idle exhaust passage with the housing unit, the second idle exhaust passage portion being located above a portion of the cooling system, the gasket isolating the second idle exhaust passage portion from the cooling system portion.

11. The outboard motor as set forth in claim 10 additionally comprising a lubrication system arranged to lubricate the engine, the housing unit including a portion defining a lubricant tank of the lubrication system, the gasket including a portion that is interposed between the intermediate member and the lubricant tank.

12. The outboard motor as set forth in claim 10, wherein the intermediate member further defines an idle expansion chamber disposed downstream the second idle exhaust passage portion with the housing unit.

13. An outboard motor comprising an internal combustion engine, an intermediate member supporting the engine, a housing unit supporting the intermediate member, an exhaust system configured to guide exhaust gases from the engine, the exhaust system including a main exhaust passage and an idle exhaust passage, the main exhaust passage configured to discharge exhaust gases produced at engine speeds above idle to the body of water through the housing unit, the idle exhaust passage configured to discharge exhaust gases produced at idle engine speeds to the atmosphere, the intermediate member defining at least a portion of the main exhaust passage and a portion of the idle exhaust passage, the intermediate member forming a recessed area in the main exhaust passage portion, the idle exhaust passage communicating with the main exhaust passage portion at the recessed area, a cooling system arranged to cool at least the engine, the intermediate member defining a coolant jacket of the cooling system disposed adjacent to the main exhaust passage portion, the intermediate member defining two apertures that open to an exterior of the intermediate member and extend parallel to each other, and closure members closing respective openings of the apertures, one of the apertures forming the portion of the idle exhaust passage, and the other one of the apertures forming a portion of the coolant jacket.

14. The outboard motor as set forth in claim 13, wherein at least the idle exhaust passage portion and a portion of the coolant jacket extend generally parallel to each other.

15. The outboard motor as set forth in claim 13, wherein the closure member closing the coolant jacket portion is detachably affixed to the intermediate member and carries an anode extending through the coolant jacket portion.

16. An outboard motor comprising an internal combustion engine, a housing unit disposed below the engine, an exhaust system configured to guide exhaust gases from the engine, the exhaust system including a main exhaust passage and an idle exhaust passage, the main exhaust passage being configured to discharge exhaust gases produced at engine speeds above idle to the body of water through the housing unit, the idle exhaust passage being configured to discharge exhaust gases produced at idle engine speeds to the atmosphere, an exhaust guide member defining a portion of the main exhaust passage, the exhaust guide member forming a recessed area in the main exhaust passage portion, and an exhaust conduit communicating with the main exhaust passage portion to form a further portion of the main exhaust passage downstream from the main exhaust portion defined by the exhaust guide member, the idle exhaust passage being branched from the main exhaust passage portion at the recessed area and proximate to the exhaust conduit, the idle exhaust passage extending from the main exhaust passage at an acute angle relative to a direction of exhaust gas flow in the main exhaust passage.

17. An outboard motor comprising an internal combustion engine, a housing unit disposed below the engine, an exhaust system configured to guide exhaust gases from the engine, the exhaust system including a main exhaust passage and an idle exhaust passage, the main exhaust passage configured to discharge exhaust gases produced at engine speeds above idle to the body of water through the housing unit, the idle exhaust passage configured to discharge exhaust gases produced at idle engine speeds to the atmosphere, and an exhaust guide member disposed between the engine and the housing unit, the exhaust guide member defining a portion of the main exhaust passage, the exhaust passage portion forming a dugout area recessed relative to exhaust gas flow in the main exhaust passage, the idle exhaust passage being branched from the main exhaust passage portion at the dugout area, the idle exhaust passage extending at an acute angle relative to a direction of the exhaust gas flow in the main exhaust passage.

18. An outboard motor comprising an internal combustion engine, a housing unit disposed below the engine, an exhaust system configured to guide exhaust gases from the engine, the exhaust system including a first exhaust passage and a second exhaust passage, the first exhaust passage configured to discharge exhaust gases to the body of water through the housing unit at relatively high engine speeds, the second exhaust passage configured to discharge exhaust gases to the atmosphere at relatively low engine speeds, and a support member arranged to support the engine, the support member defining a portion of the first exhaust passage, the support member forming a recessed area in the first exhaust passage portion, the second exhaust passage being branched from the first exhaust passage portion at a port formed in the recessed area, the recessed area being formed such that a step, which is defined between the first exhaust passage portion and a portion of the recessed area, includes an edge that extends upward.

19. A method for forming an exhaust guide member of an outboard motor, the exhaust guide member defining a main exhaust passage and a secondary exhaust passage branched from the main exhaust passage within the exhaust guide member, the method comprising placing a first mold in a cast frame of the exhaust guide member, placing a second mold in the cast frame, casting the exhaust guide member, removing the first mold from the cast frame, removing the second mold from the cast frame in a direction opposed to a direction in which the first mold is removed, the first mold being larger than the second mold in a direction generally normal to the respective removing directions of the first and second molds, and the first and second molds being substantially equal in size in a direction generally parallel to the respective removal directions of the first and second molds, and boring an aperture in a recessed area formed by the first mold.

20. An outboard motor comprising an internal combustion engine, an intermediate member supporting the engine, a housing unit supporting the intermediate member, an exhaust system configured to guide exhaust gases from the engine, the exhaust system including a main exhaust passage and an idle exhaust passage, the main exhaust passage configured to discharge exhaust gases produced at engine speeds above idle to the body of water through the housing unit, the idle exhaust passage configured to discharge exhaust gases produced at idle engine speeds to the atmosphere, a cooling system arranged to cool at least part of the exhaust system extending within the housing unit, and a gasket interposed between the intermediate member and the housing unit, the intermediate member defining a portion of the idle exhaust passage with the housing unit, the idle exhaust passage portion being located above a portion of the cooling system, the gasket isolating the idle exhaust passage portion from the cooling system portion.

21. The outboard motor as set forth in claim 20, wherein the intermediate member further defines an idle expansion chamber disposed downstream the idle exhaust passage portion with the housing unit.

22. An outboard motor comprising an internal combustion engine, a housing unit disposed below the engine, an intermediate member disposed between the engine and the housing unit, an exhaust system arranged to discharge exhaust gases from the engine, the exhaust system including a first exhaust passage and a second exhaust passage branched from the first exhaust passage, the first exhaust passage including a portion extending within the housing unit, a cooling system arranged to cool at least the portion of the first exhaust passage, the second exhaust passage including a portion extending within the intermediate member and facing a portion of the cooling system, and a gasket interposed between the intermediate member and the housing unit to isolate the portion of the second exhaust passage from the portion of the cooling system.

23. The outboard motor as set forth in claim 22, wherein the intermediate member further defines at least a portion of a voluminous chamber communicating with the second exhaust passage.

24. The outboard motor as set forth in claim 22, wherein the second exhaust passage communicates with the atmosphere.

25. The outboard motor as set forth in claim 22, wherein the portion of the cooling system includes a coolant pool.