Claims
- 1. An operator-carried, lightweight power tool comprising a frame with an implement mounted thereon, a four-stroke internal combustion engine with a crankshaft drivably connected to said implement, said engine being supported by said frame;said engine comprising a crankcase with a lubrication oil chamber, a cylinder block secured to said crankcase and having a cylinder bore and a cam chamber; a cylinder head secured to said cylinder block; overhead intake and exhaust valve ports in said cylinder head; a valve cover defining a valve chamber, said valve chamber enclosing intake and exhaust valves which register with said intake and exhaust valve ports; a cam and cam drive mechanism in said cam chamber, said cam drive mechanism including valve operating push rods; a rocker arm assembly in said valve chamber drivably connecting said push rods and said intake and exhaust valves; at least one push rod opening and at least one of said push rods extending through said push rod opening; said crankcase lubrication oil chamber being in communication with said valve chamber through said push rod opening; an oil mist generator drivably connected to said crankshaft, liquid oil in said lubrication oil chamber being agitated by said oil mist generator into an oil mist; an open passageway between said lubrication oil chamber and said cam chamber whereby said lubrication oil chamber, said cam chamber and said valve chamber define a closed oil mist containment permitting lubrication oil mist distribution throughout the engine; a crankshaft passage formed in said crankshaft including a crankcase gas flow entrance portion extending in a radially outward direction from said crankshaft; said engine having an air/fuel induction system communicating with said intake valve port; and oil mist flow passage structure extending from said crankshaft passage to said induction system whereby crankcase gases are scavenged.
- 2. The power tool set forth in claim 1 wherein said crankshaft passage rotates with said crankshaft and develops centrifugal force on liquid oil and liquid oil droplets to effect lean crankcase gas distribution to said induction system.
- 3. An operator-carried, lightweight power tool comprising a frame with an implement mounted thereon, a four-stroke internal combustion engine with a crankshaft drivably connected to said implement, said engine being supported by said frame;said engine comprising a crankcase with a is lubrication oil chamber, a cylinder block secured to said crankcase having a cylinder bore and a cam chamber; an oil mist generator drivably connected to said crankshaft, said generator acting on and agitating liquid oil in said crankcase chamber to develop an oil mist; a cylinder head secured to said cylinder block; overhead intake and exhaust valve ports in said cylinder head; a valve cover defining a valve chamber, said valve chamber enclosing intake and exhaust valves that register with said intake and exhaust ports; a crankshaft passage formed in said crankshaft including an oil mist flow entrance portion extending in a radially outward direction from said crankshaft; said engine having an air/fuel induction system communicating with said intake valve port; and oil mist flow passage structure extending from said crankshaft passage to said induction system whereby crankcase gases are scavenged.
- 4. The power tool set forth in claim 3 wherein said crankshaft passage rotates with said crankshaft and develops centrifugal force on liquid oil and liquid oil droplets to effect lean crankcase gas distribution to said induction system.
- 5. An internal combustion engine comprising a crankcase with a lubrication oil chamber, a cylinder block secured to said crankcase and having a cylinder bore and a cam chamber;a cylinder head secured to said cylinder block; overhead intake and exhaust valve ports in said cylinder head; a valve cover defining a valve chamber, said valve chamber enclosing intake and exhaust valves which register with said intake and exhaust valve ports; a cam and cam drive mechanism in said cam chamber, said cam drive mechanism including valve operating push rods; a rocker arm assembly in said valve chamber drivably connecting said push rods and said intake and exhaust valves; at least one push rod opening and at least one of said push rods extending through said push rod opening; said crankcase lubrication oil chamber being in communication with said valve chamber through said push rod opening; an oil mist generator drivably connected to said crankshaft, liquid oil in said lubrication oil chamber being agitated by said oil mist generator into an oil mist; an open passageway between said lubrication oil chamber and said cam chamber whereby said lubrication oil chamber, said cam chamber and said valve chamber define a closed oil mist containment permitting lubrication oil mist distribution throughout the engine; a crankshaft passage formed in said crankshaft including a crankcase gas flow entrance portion extending in a radially outward direction from said crankshaft; said engine having an air/fuel induction system communicating with said intake valve port; and oil mist flow passage structure extending from said crankshaft passage to said induction system whereby crankcase gases are scavenged.
- 6. A four-stroke internal combustion engine comprising a crankcase with a lubrication oil chamber, a cylinder block secured to said crankcase and having a cylinder bore and a cam chamber;a cylinder head secured to said cylinder block; intake and exhaust valve ports in said cylinder head; a valve cover defining a valve chamber, said valve chamber enclosing intake and exhaust valves which register with said intake and exhaust valve ports; lubrication oil distribution means for distributing oil from said crankcase lubrication oil chamber throughout said engine including said valve cover; a crankshaft passage formed in said crankshaft including a crankcase gas flow entrance portion extending in a radially outward direction from said crankshaft; said engine having an air/fuel induction system communication with said intake valve port; and crankcase gas flow passage structure extending from said crankshaft passage to said induction system whereby crankcase gases are scavenged.
Parent Case Info
This application is a continuation of application Ser. No. 09/035,552, filed Mar. 5, 1998, now U.S. Pat. No. 6,039,020.
US Referenced Citations (25)
Non-Patent Literature Citations (1)
Entry |
Katsumi Kurihara, Shiro Kawamoto and James Grayson, Multi-Position Operable Four-Cycle Engine; Mar. 8, 1996; Ser. No. 08/614,835. |
Continuations (1)
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Number |
Date |
Country |
Parent |
09/035552 |
Mar 1998 |
US |
Child |
09/488218 |
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US |