Internal combustion engine having a variable valve control system, and method of using same

An internal combustion engine comprising a cylinder head and a variable valve control system in which a rocker arm is disposed between an engine valve and first and second cams for the engine valve, wherein the rocker arm is pivotally supported by a rocker arm shaft and is slidably movable thereon in an axial direction of the rocker arm shaft, in response to a movement of the rocker arm shaft, to selectively engage with one of said cams, whereby control of the engine valve is switchable between said cams, said internal combustion engine comprising:

• a support shaft supported on said cylinder head so as to be parallel with the rocker arm shaft;
• a stopper pivotally supported on said support shaft, wherein the stopper includes a pair of substantially plate-shaped engagement nails which are spaced apart in the axial direction of the support shaft, and which extend outwardly from a support-shaft side thereof towards the rocker arm;
• wherein the rocker arm has three engagement grooves formed therein for selectively engaging the corresponding engagement nails;
• and two deck-like portions, each of which is located between two of the engagement grooves which are adjacent to one another,
• wherein the engagement nails are formed in such different shapes and the engagement grooves are formed in such different shapes as to disengage only a first one of the engagement nails from a corresponding one of the engagement grooves in response to a swinging state of the stopper, and
• wherein the rocker arm is configured and arranged such that while out of engagement with the corresponding one of the engagement grooves, said first one of the engagement nails is put on the deck-like portion so as to disengage a second one of the engagement nails from the corresponding one of the engagement grooves in association with a swing state of the rocker arm,
• and wherein the system is operable in a manner such that:
• when the stopper swings towards the rocker arm, the engagement nails selectively engage respectively with two of the three engagement grooves to temporarily prevent the rocker arm from sliding,
• when the stopper swings away from the rocker arm, the engagement nails disengage from their respective engagement grooves to allow the rocker arm to slide,
• the shapes of the engagement nails differ from each other when viewed in the axial direction of the support shaft, and the shapes of the deck-like portions differ from each other when viewed in the axial direction of the rocker arm shaft, and thereby the disengaging timings for the engagement nails from their respective engagement grooves differ from each other,
• when the stopper swings away from the rocker arm by a predetermined amount, the first one of the engagement nails in engagement with a corresponding one of the engagement grooves disengages from the corresponding first one of the engagement grooves, but the second one of the engagement nails still engages with a corresponding second one of the engagement grooves, and the disengaged first engagement nail is placed on top of one of the deck-like portions,
• and when an action of the rocker arm subsequently makes the stopper swing further away from the rocker arm, the second engagement nail disengages from the corresponding second one of the engagement grooves.

A method of operating a variable valve control system of an internal combustion engine equipped with a cylinder head in which a rocker arm is disposed between an engine valve and first and second cams for the engine valve, wherein the rocker arm is pivotally supported by a rocker arm shaft and is slidably movable in an axial direction of the rocker arm shaft, in response to a movement of the rocker arm shaft, to selectively engage with one of said cams, whereby control of the engine valve is switchable between said cams, said method comprising the steps of:

• a) pivotally moving a stopper on a support shaft attached to the cylinder head of the internal combustion engine to place a first engagement nail of said stopper on a first deck-like portion of the rocker arm, where said support shaft is parallel with the rocker arm shaft, and wherein the stopper comprises a pair of substantially plate-shaped engagement nails which are spaced apart in the axial direction of the support shaft, and which extend outwardly from a support-shaft side thereof towards the rocker arm;
• wherein the rocker arm has at least three engagement grooves formed therein for selectively engaging the corresponding engagement nails;
• and two deck-like portions, each of which is located between two of the engagement grooves which are adjacent to one another,
• wherein the engagement nails are formed in such different shapes and the engagement grooves are formed in such different shapes as to disengage only a first one of the engagement nails from a corresponding one of the engagement grooves in response to the pivotal movement of the stopper, and
• b) disengaging a second one of the engagement nails from a corresponding one of the engagement grooves in association with a swing state of the rocker arm.