Internal-combustion engines – Two-cycle – Whirl through piston-controlled ports
Reexamination Certificate
2000-03-31
2001-07-03
Kamen, Noah P. (Department: 3747)
Internal-combustion engines
Two-cycle
Whirl through piston-controlled ports
C123S323000
Reexamination Certificate
active
06253718
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an exhaust control valve assembly for an engine, such as a two-cycle engine.
2. Description of the Relevant Art
In accordance with the background art, an exhaust control valve for a two-cycle engine includes a pair of valve elements. The valve elements are formed symmetrically. The valve elements sandwich a reinforcing wall, which laterally bisects a central section of an opening to a cylinder bore of an exhaust port. Such as arrangement in disclosed, for example, in Japanese Patent Laid-Open Publication No. Sho. 63-306227.
The background art's exhaust control valve suffers drawbacks. When the exhaust control valve is heated up by exhaust gases, while the engine is running, the valve element nearest to a pouch-shaped bearing hole-side tends to overheat. Overheating the valve element on this side reduces that valve element's resistance to heat, which further inclines the valve element to fail.
SUMMARY OF THE INVENTION
The present inventors have discovered the source of the drawback and invented a solution to the drawback. Exhaust heat, received by each valve element, is transmitted to that valve element's boss. The boss, in turn, transmits the heat to the valve stem. Heat in the valve stem propagates along the valve stem and to the ends of the valve stem. One end of the valve stem passes through a bearing through hole and is connected to the drive system for imparting rotation to the valve stem. The one end of the valve stem has relatively good heat dissipation. Another end of the valve stem is captured within the pouch-shaped bearing hole. The another end of the valve stem tends to trap heat.
It is therefore the object of the present invention to provide an exhaust control valve assembly with good attributes for dissipating heat.
It is another object of the present invention to provide an exhaust control valve assembly which dissipates heat in a relatively even manner.
These and other objects of the invention are accomplished by an engine comprising: a cylinder block having a cylinder bore; an exhaust opening at an inner wall of said cylinder bore; an exhaust port connected to said exhaust opening, said exhaust port having a first wall and a second wall; a dividing wall connecting said first wall and said second wall, so as to divide said exhaust port generally along a dividing plane; an exhaust control valve including a first valve element and a second valve element, said first valve element including a first face facing said cylinder bore and a first boss distal to said first face, said second valve element including a second face facing said cylinder bore and a second boss distal to said second face, said first face residing on one side of said dividing wall and said second face residing on another side of said dividing wall; and a valve stem connected to said first boss and said second boss to impart movement to said first boss and said second boss, a first end of said valve stem extending beyond said first boss and being supported for movement at a first location, a second end of said valve stem extending beyond said second boss and being supported for movement at a second location, wherein said first boss is connected to a first length of said valve stem, which passes through said dividing plane of said exhaust port.
Further, these and other objects of the invention are accomplished by an engine comprising: a cylinder block having a cylinder bore; an exhaust opening at an inner wall of said cylinder bore; an exhaust port connected to said exhaust opening, said exhaust port having a first wall and a second wall; a dividing wall connecting said first wall and said second wall, so as to divide said exhaust port generally along a dividing plane; an exhaust control valve including a first valve element and a second valve element, said first valve element including a first face facing said cylinder bore and a first boss distal to said first face, said second valve element including a second face facing said cylinder bore and a second boss distal to said second face, said first face residing on one side of said dividing wall and said second face residing on another side of said dividing wall; and a valve stem connected to said first boss and said second boss to impart movement to said first boss and said second boss, a first end of said valve stem extending beyond said first boss and being supported for movement at a first location, a second end of said valve stem extending beyond said second boss and being supported for movement at a second location, wherein said first boss extends along a first length of said valve stem and said second boss extends along a second length of said valve stem, and a total of said first length and said second length of said valve stem resides closer to said second location, as opposed to closer to said first location.
Moreover, these and other objects of the invention are accomplished by an engine comprising: a cylinder block having a cylinder bore; an exhaust opening at an inner wall of said cylinder bore; an exhaust port connected to said exhaust opening, said exhaust port having a first wall and a second wall; a dividing wall connecting said first wall and said second wall, so as to divide said exhaust port generally along a dividing plane; an exhaust control valve including a first valve element and a second valve element, said first valve element including a first face facing said cylinder bore and a first boss distal to said first face, said second valve element including a second face facing said cylinder bore and a second boss distal to said second face, said first face residing on one side of said dividing wall and said second face residing on another side of said dividing wall; and a valve stem connected to said first boss and said second boss to impart movement to said first boss and said second boss, a first end of said valve stem extending beyond said first boss and being supported for movement at a first location, a second end of said valve stem extending beyond said second boss and being supported for movement at a second location, wherein said dividing wall is located in a central section of said exhaust port and bisects said exhaust port into a first section and a second section which are substantially equal in cross section, said first section being located nearest said first location and said second section being located nearest said second location, said first boss extends along a first length of said valve stem and said second boss extends along a second length of said valve stem, and a total of said first length and said second length of said valve stem resides more in said second section, as opposed to residing more in said first section.
Other objects and further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.
REFERENCES:
patent: 63-306227 (1988-12-01), None
Fukusho Tsutomu
Hara Shigeyuki
Uchida Hiroyuki
Birch & Stewart Kolasch & Birch, LLP
Honda Giken Kogyo Kabushiki Kaisha
Kamen Noah P.
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