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US 7,503,297 B2Granted
Valve drive mechanism for engine
AssigneeYamaha Hatsudoki Kaisha
InventorsHideo Fujita, Atsushi Suzuki
Life of this patent
Estimating the term…
Abstract
A valve drive mechanism for an engine can include a drive shaft that is configured for rotation about an axis. A valve member is configured to be driven by the rotation of the drive shaft to open and close a valve. A variable valve timing mechanism is positioned at least partially between the valve member and the drive shaft. The variable valve timing mechanism is configured to vary a valve open period of the valve. The valve drive mechanism is configured such that, during a specific operation range, the valve open period includes a main valve open period during which the valve is open in a suction or exhaust stroke, and a sub valve open period during which the valve is open in an expansion or compression stroke.
Claims28
A valve drive mechanism for an engine, the valve drive mechanism comprising:
- a drive shaft that is configured for rotation about an axis;
- a valve member that is configured to be driven by the rotation of the drive shaft to open and close a valve;
- and
- a variable valve mechanism positioned at least partially between the valve member and the drive shaft, the variable valve mechanism configured to vary a valve open period of the valve;
- wherein the variable valve mechanism is configured such that, during a specific operation range, the valve open period includes a main valve open period during which the valve is open in a suction or exhaust stroke, and a sub valve open period during which the valve is open in an expansion or compression stroke;
- wherein the variable valve mechanism comprises a rocker cam having a main lift portion on one end and a sub lift portion on an opposite end, the main lift portion configured to engage the valve member during the main valve open period, and the sub lift portion configured to engage the valve member during the sub valve open period.
3 more elements
A valve drive mechanism for an engine, the valve drive mechanism comprising:
- a drive shaft that is configured for rotation about an axis;
- a valve member that is configured to be driven by the rotation of the drive shaft to open and close a valve;
- and
- a variable valve mechanism positioned at least partially between the valve member and the drive shaft, the variable valve mechanism configured to vary a valve open period of the valve;
- wherein the variable valve mechanism is configured such that, during a specific operation range, the valve open period includes a main valve open period during which the valve is open in a suction or exhaust stroke, and a sub valve open period during which the valve is open in an expansion or compression stroke;
- wherein the drive shaft is an intake camshaft, the valve member comprises a rocker arm supported for rocking motion on a shaft, the variable valve mechanism comprises a rocker cam that is supported for rocking motion and is configured to be driven by the intake camshaft, and an intermediate rocker rockably interposed between a cam face of the rocker cam and the rocker arm;
- the intermediate rocker configured to be pressed with the cam face as the rocker cam rocks to rock the rocker arm, and the open period and the lift amount of the intake valve is made continuously controllable by changing relative positional relationship between the intermediate rocker and the cam face.
4 more elements
A valve drive mechanism for an engine, the valve drive mechanism comprising:
- a drive shaft that is configured for rotation about an axis;
- a valve member that is configured to be driven by the rotation of the drive shaft to open and close a valve;
- a variable valve mechanism positioned at least partially between the valve member and the drive shaft, the variable valve mechanism configured to continuously vary a valve open period of the valve;
- and
- means for opening the valve in a suction or exhaust stroke for a first period of time and opening the valve in an expansion or compression stroke for a second period of time that is smaller than the first period of time
- wherein the variable valve mechanism comprises a rocker cam having a main lift portion on one end and a sub lift portion on an opposite end, the main lift portion configured to engage the valve member during the main valve open period, and the sub lift portion configured to engage the valve member during the sub valve open period.
3 more elements
A method of operating a four-cycle internal combustion engine comprising:
- during a first operating condition, operating the internal combustion engine through a combustion cycle comprising a suction stroke, a compression stroke, an expansion stroke, and an exhaust stroke;
- during the combustion cycle, opening a valve during the suction or the exhaust stroke for a first period of time and then substantially closing the valve;
- and
- during the same combustion cycle, opening the same valve during an expansion or compression stroke for a second period of time and then substantially closing the valve;
- wherein the valve is opened and closed using a variable valve mechanism, the variable valve mechanism comprising a rocker cam having a main lift portion on one end and a sub lift portion on an opposite end, the main lift portion configured to engage the valve member during the first period of time, and the sub lift portion configured to engage the valve member during the second period of time.
2 more elements
A method of operating a four-cycle internal combustion engine comprising:
- during a first operating condition, operating the internal combustion engine through a combustion cycle comprising a suction stroke, a compression stroke, an expansion stroke, and an exhaust stroke;
- during the combustion cycle, opening a valve during the suction or the exhaust stroke for a first period of time and then substantially closing the valve;
- during the same combustion cycle, opening the same valve during an expansion or compression stroke for a second period of time and then substantially closing the valve;
- and
- further comprising, during a second operating condition, operating the internal combustion engine through a second combustion cycle comprising a suction stroke, a compression stroke, an expansion stroke, and an exhaust stroke, opening the valve during the suction or exhaust stroke for the third period of time and not opening the same valve during an expansion or compression stroke.
2 more elements
A method of operating a four-cycle internal combustion engine comprising:
- during a first operating condition, operating the internal combustion engine through a combustion cycle comprising a suction stroke, a compression stroke, an expansion stroke, and an exhaust stroke;
- during the combustion cycle, opening a valve during the suction or the exhaust stroke for a first period of time and then substantially closing the valve;
- during the same combustion cycle, opening the same valve during an expansion or compression stroke for a second period of time and then substantially closing the valve;
- and
- wherein operating the first operating conditions corresponds to a condition in which the internal combustion engine is idling.
2 more elements
Dependencies are inferred from the claim text.