Four cycle outboard motor

An outboard motor having a high-performance V-type twin overhead cam four-cycle internal combustion engine. The oil reservoir for the engine is disposed in a driveshaft housing below the engine and an oil pump is driven off the lower end of the engine crankshaft for circulating the oil from the oil tank to the engine. The oil supply system for the engine includes a vertically extending main gallery and a drain passage which extend in parallel side-by-side relationship and which are disposed over the oil tank for ease of oil return. The exhaust and cooling system for the engine is configured so as to minimize heat transfer between the exhaust system and the lubricating system and to maintain a compact assembly.

We claim:

1. An outboard motor comprised of a powerhead consisting of a four-cycle internal combustion engine and a surrounding protective cowling, said engine including a crankshaft journaled for rotation about a vertically extending axis, a driveshaft housing and lower unit depending from said powerhead and journaling a driveshaft for rotation about a vertically extending axis, a propulsion device driven by said driveshaft for propelling an associated watercraft, means for coupling said crankshaft for rotation with said driveshaft for driving said driveshaft from said crankshaft, an oil reservoir for containing lubricant for said engine disposed beneath said engine, a flywheel fixed for rotation with said crankshaft at the lower end of said engine and above the coupling of said driveshaft to said crankshaft, and an oil pump driven by said crankshaft at a point below said flywheel for circulating lubricant between said oil reservoir and said engine.

2. An outboard motor as set forth in claim 1, wherein the flywheel is contained at least in part in a housing.

3. An outboard motor as set forth in claim 2, wherein the flywheel housing forms at least in part a flow path for the oil pumped by the oil pump.

4. An outboard motor as set forth in claim 3, wherein the flywheel housing forms at least in part a flow path from the oil reservoir to the oil pump.

5. An outboard motor as set forth in claim 3, wherein the flywheel housing forms at least in part a flow path from the oil pump to the engine.

6. An outboard motor as set forth in claim 5, wherein the flywheel housing also forms at least in part a flow path from the oil reservoir to the oil pump.

7. An outboard motor as set forth in claim 2, further including means for ventilating the interior of the housing.

8. An outboard motor as set forth in claim 2, wherein the oil pump is positioned in the lower portion of the housing.

9. An outboard motor as set forth in claim 2, wherein the engine is comprised of a cylinder block having a crankcase chamber formed at one end thereof in which the crankshaft rotates and at least one cylinder bore extending horizontally from said crankcase chamber, a main oil gallery formed in said cylinder block in proximity to said crankcase chamber for delivering oil to at least main bearings of said crankshaft for their lubrication, a drain path formed in said cylinder block in parallel relationship to said main oil gallery for returning oil to the oil reservoir by gravity flow.

10. An outboard motor as set forth in claim 9, wherein the flywheel housing forms at least in part a flow path for the oil pumped by the oil pump.

11. An outboard motor as set forth in claim 10, wherein the flywheel housing forms at least in part a flow path from the oil reservoir to the oil pump.

12. An outboard motor as set forth in claim 10, wherein the flywheel housing forms at least in part a flow path from the oil pump to the engine.

13. An outboard motor as set forth in claim 12, wherein the flywheel housing also forms at least in part a flow path from the oil reservoir to the oil pump.

14. An outboard motor as set forth in claim 9, wherein the cylinder block has a pair of angularly disposed cylinder banks each of which is formed with at least one cylinder bore with a valley formed between said cylinder banks.

15. An outboard motor as set forth in claim 14, wherein the main oil gallery is formed at the base of the valley.

16. An outboard motor as set forth in claim 14, wherein the drain path is formed at the base of the valley.

17. An outboard motor as set forth in claim 16, wherein the main oil gallery is also formed at the base of the valley.

18. An outboard motor as set forth in claim 16, wherein the flywheel housing forms at least in part a flow path for the oil pumped by the oil pump.

19. An outboard motor as set forth in claim 18, wherein the flywheel housing forms at least in part a flow path from the oil reservoir to the oil pump.

20. An outboard motor as set forth in claim 18, wherein the flywheel housing forms at least in part a flow path from the oil pump to the engine.

21. An outboard motor as set forth in claim 20, wherein the flywheel housing also forms at least in part a flow path from the oil reservoir to the oil pump.

22. An outboard motor as set forth in claim 9, wherein the cylinder block is formed with webs that provide journals for the crankshaft.

23. An outboard motor as set forth in claim 22, wherein the cylinder block webs are formed with lubricating passages intersecting the main gallery for lubricating the crankshaft journals.

24. An outboard motor as set forth in claim 23, wherein the web lubricating passages are higher at their connection to the main oil gallery than at the crankshaft journals.

25. An outboard motor as set forth in claim 24, wherein the cylinder block has a pair of angularly disposed cylinder banks each of which is formed with at least one cylinder bore with a valley formed between said cylinder banks.

26. An outboard motor as set forth in claim 25, wherein the drain passage is closer to the valley than the main oil gallery.

27. An outboard motor as set forth in claim 25, wherein the cylinder block has a wall separating the crankcase chamber from the drain path and further including drain openings in said wall adjacent and above the webs.

28. An outboard motor as set forth in claim 9, further including an exhaust guide interposed between the lower end of the engine and the upper end of the driveshaft housing and lower unit, an exhaust discharge system in said drive shaft housing and lower unit for discharging exhaust gases to the atmosphere, said exhaust gas discharge system including at least one expansion chamber, said engine having at least one exhaust port opening at an outer face of said engine in a transverse direction within said powerhead, said exhaust guide being formed with an exhaust passage disposed beneath said engine and overlaid by said engine, and an exhaust manifold assembly for conveying exhaust gases transversely outwardly from said exhaust port, then vertically downwardly and at its lower end transversely inwardly beneath said engine and communicating with said exhaust guide exhaust passage.

29. An outboard motor as set forth in claim 28, wherein the cylinder block has a pair of angularly disposed cylinder banks each of which is formed with at least one cylinder bore with a valley formed between said cylinder banks, each of said cylinder banks having at least one exhaust port served by an exhaust manifold as described.

30. An outboard motor as set forth in claim 29, wherein the exhaust guide is formed with two exhaust passages each served by a respective one of the exhaust manifolds.

31. An outboard motor as set forth in claim 28, wherein the engine has a cooling jacket, and further including a water pump positioned in the driveshaft housing and lower unit, and driven by the driveshaft for circulating cooling water from the body of water in which the associated watercraft is operating to said engine cooling jacket, said coolant supply passing, at least in part, across the lower face of said oil reservoir for cooling said oil reservoir.

32. An outboard motor as set forth in claim 31, wherein the exhaust manifold has a cooling jacket through which the cooling water from the water pump passes.

33. An outboard motor as set forth in claim 32, wherein the cooling water passes first across the oil reservoir, then through the exhaust manifold cooling jacket and then to the engine cooling jacket.

34. An outboard motor comprised of a powerhead consisting of a four-cycle internal combustion engine and a surrounding protective cowling, said engine including a crankshaft journaled for rotation about a vertically extending axis, a driveshaft housing and lower unit depending from said powerhead and journaling a driveshaft for rotation about a vertically extending axis and including a propulsion device driven by said driveshaft for propelling an associated watercraft, means for coupling said crankshaft for rotation with said driveshaft for driving said driveshaft from said crankshaft, an oil reservoir for containing lubricant for said engine disposed beneath said engine, said engine being comprised of a cylinder block having a crankcase chamber formed at one end thereof by a separate crankcase member detachably affixed to said cylinder block at said one end, said crankshaft being journaled in said crankcase chamber, said cylinder block having at least one cylinder bore extending horizontally from said crankcase chamber, a main oil gallery formed in said cylinder block in proximity to said crankcase chamber for delivering oil to at least main bearings of said crankshaft for their lubrication, a drain path formed in said cylinder block in parallel relationship to said main oil gallery for returning oil to said oil reservoir by gravity flow, and an oil pump driven by said engine for pumping oil from said oil reservoir to said main oil gallery.

35. An outboard motor as set forth in claim 34, wherein the cylinder block is formed with webs that provide journals for the crankshaft.

36. An outboard motor as set forth in claim 35, wherein the cylinder block webs are formed with lubricating passages intersection the main gallery for lubricating the crankshaft journals.

37. An outboard motor comprised of a powerhead consisting of a four-cycle internal combustion engine and a surrounding protective cowling, said engine including a crankshaft journaled for rotation about a vertically extending axis, a driveshaft housing and lower unit depending from said powerhead and journaling a driveshaft for rotation about a vertically extending axis and including a propulsion device driven by said driveshaft for propelling an associated watercraft, means for coupling said crankshaft for rotation with said driveshaft for driving said driveshaft from said crankshaft, an oil reservoir for containing lubricant for said engine disposed beneath said engine, said engine being comprised of a cylinder block having a crankcase chamber formed at one end thereof in which said crankshaft rotates and a pair of angularly disposed cylinder banks each of which is formed with at least one cylinder bore with a valley formed between said cylinder banks, said cylinder bores extending horizontally from said crankcase chamber, a main oil gallery formed in said cylinder block in proximity to said crankcase chamber for delivering oil to at least main bearings of said crankshaft for their lubrication, a drain path formed in said cylinder block in parallel relationship to said main oil gallery for returning oil to said oil reservoir by gravity flow, and an oil pump driven by said engine for pumping oil from said oil reservoir to said main oil gallery.

38. An outboard motor as set forth in claim 37, wherein the main oil gallery is formed at the base of the valley.

39. An outboard motor as set forth in claim 37, wherein the drain path is formed at the base of the valley.

40. An outboard motor as set forth in claim 39, wherein the main oil gallery is also formed at the base of the valley.

41. An outboard motor comprised of a powerhead consisting of a four-cycle internal combustion engine and a surrounding protective cowling, said engine including a crankshaft journaled for rotation about a vertically extending axis, a driveshaft housing and lower unit depending from said powerhead and journaling a driveshaft for rotation about a vertically extending axis and including a propulsion device driven by said driveshaft for propelling an associated watercraft, means for coupling said crankshaft for rotation with said driveshaft for driving said driveshaft from said crankshaft, an oil reservoir for containing lubricant for said engine disposed beneath said engine, said engine being comprised of a cylinder block having a crankcase chamber formed at one end thereof in which said crankshaft rotates and at least one cylinder bore extending horizontally from said crankcase chamber, a main oil gallery formed in said cylinder block in proximity to said crankcase chamber for delivering oil to at least main bearings of said crankshaft for their lubrication, a drain path formed in said cylinder block in parallel relationship to said main oil gallery for returning oil to said oil reservoir by gravity flow, and an oil pump driven by said engine for pumping oil from said oil reservoir to said main oil gallery, said cylinder block being formed with webs that provide journals for said crankshaft, said cylinder block webs being formed with lubricating passages intersecting said main gallery for lubricating said crankshaft journals, said web lubricating passages being higher at their connection to said main oil gallery than at said crankshaft journals.

42. An outboard motor as set forth in claim 41, wherein the cylinder block has a pair of angularly disposed cylinder banks each of which is formed with at least one cylinder bore with a valley formed between said cylinder banks.

43. An outboard motor as set forth in claim 42, wherein the drain passage is closer to the valley than the main oil gallery.

44. An outboard motor as set forth in claim 43, wherein the cylinder block has a wall separating the crankcase chamber from the drain path and further including drain openings in said wall adjacent and above the webs.

45. An outboard motor comprised of a powerhead consisting of a four-cycle internal combustion engine and a surrounding protective cowling, said engine including a crankshaft journaled for rotation about a vertically extending axis, a driveshaft housing and lower unit depending from said powerhead and journaling a driveshaft for rotation about a vertically extending axis and including a propulsion device driven by said driveshaft for propelling an associated watercraft, means for coupling said crankshaft for rotation with said driveshaft for driving said driveshaft from said crankshaft, an exhaust guide interposed between the lower end of said engine and the upper end of said driveshaft housing and lower unit, an exhaust discharge system in said drive shaft housing and lower unit for discharging exhaust gases to the atmosphere, said exhaust gas discharge system including at least one expansion chamber, said engine having at least one exhaust port opening at an outer face of said engine in a transverse direction within said powerhead, said exhaust guide being formed with an exhaust passage disposed beneath said engine and overlied by said engine, and an exhaust manifold assembly for conveying exhaust gases transversely outwardly from said exhaust port, then vertically downwardly and at its lower end transversely inwardly beneath said engine and communicating with said exhaust guide exhaust passage.

46. An outboard motor as set forth in claim 45, wherein the cylinder block has a pair of angularly disposed cylinder banks each of which is formed with at least one cylinder bore with a valley formed between said cylinder banks, each of said cylinder banks having at least one exhaust port served by an exhaust manifold as described.

47. An outboard motor as set forth in claim 46, wherein the exhaust guide is formed with two exhaust passages each served by a respective one of the exhaust manifolds.

48. An outboard motor as set forth in claim 45, wherein the engine has a cooling jacket, and further including a water pump positioned in the driveshaft housing and lower unit, and driven by the driveshaft for circulating cooling water from the body of water in which the associated watercraft is operating to said engine cooling jacket, said coolant supply passing, at least in part, across the lower face of said oil reservoir for cooling said oil reservoir.

49. An outboard motor as set forth in claim 48, wherein the exhaust manifold has a cooling jacket through which the cooling water from the water pump passes.

50. An outboard motor as set forth in claim 49, wherein the cooling water passes first across the oil reservoir, then through the exhaust manifold cooling jacket and then to the engine cooling jacket.

51. An outboard motor comprised of a powerhead consisting of a four-cycle internal combustion engine and a surrounding protective cowling, said engine including a crankshaft journaled for rotation about a vertically extending axis, a driveshaft housing and lower unit depending from said powerhead and journaling a driveshaft for rotation about a vertically extending axis and including a propulsion device driven by said driveshaft for propelling an associated watercraft, means for coupling said crankshaft for rotation with said driveshaft for driving said driveshaft from said crankshaft, an oil reservoir for containing lubricant for said engine disposed beneath said engine, said engine having a cooling jacket, a water pump positioned in said driveshaft housing and lower unit, and driven by said driveshaft for circulating cooling water from the body of water in which said watercraft is operating to said engine cooling jacket, said coolant supply passing, at least in part, across the lower face of said oil reservoir for cooling said oil reservoir, an exhaust guide interposed between the lower end of said engine and the upper end of said driveshaft housing and lower unit, an exhaust discharge system in said drive shaft housing and lower unit for discharging exhaust gases to the atmosphere, said exhaust gas discharge system including at least one expansion chamber, said engine having at least one exhaust port opening at an outer face of said engine in a transverse direction within said powerhead, said exhaust guide being formed with an exhaust passage disposed beneath said engine and overlaid by said engine, and an exhaust manifold assembly for conveying exhaust gases transversely outwardly from said exhaust port, then vertically downwardly and at its lower end transversely inwardly beneath said engine and communicating with said exhaust guide exhaust passage.

52. An outboard motor as set forth in claim 51, wherein the exhaust manifold has a cooling jacket through which the cooling water from the water pump passes.

53. An outboard motor as set forth in claim 52, wherein the cooling water passes first across the oil reservoir, then through the exhaust manifold cooling jacket and then to the engine cooling jacket.

54. An outboard motor as set forth in claim 53, wherein the cylinder block has a pair of angularly disposed cylinder banks each of which is formed with at least one cylinder bore with a valley formed between said cylinder banks, each of said cylinder banks having at least one exhaust port served by an exhaust manifold as described.

55. An outboard motor as set forth in claim 54, wherein each exhaust manifold has a cooling jacket through which the cooling water from the water pump passes.

56. An outboard motor as set forth in claim 55, wherein the cooling water passes first across the oil reservoir, then through the exhaust manifold cooling jackets and then to the engine cooling jacket.