Patent ID: 7886703

Claim:
A variable valve mechanism of an internal combustion engine, comprising: a valve lift varying mechanism that varies a valve lift degree of an engine valve in accordance with a turning of a control shaft; an actuation mechanism that controls the turning of the control shaft in accordance with an operation condition of the engine; a first stopper structure that stops the turning of the control shaft when the control shaft turns to a first maximum stop position in a first direction to increase the valve lift degree; a second stopper structure that stops the turning of the control shaft when the control shaft turns to a second maximum stop position in a second direction to reduce the valve lift degree; and a first biasing member that constantly biases the control shaft in the first direction, wherein, when the actuation mechanism fails to operate and thus fails to control the turning of the control shaft, the control shaft is turned to and held at an intermediate angular position between the first and second maximum stop positions by a biasing force that is produced by combining a biasing force of the first biasing member and a load that is applied to the control shaft in the second direction to reduce the valve lift degree, and wherein a curve representing a characteristic of load applied to the control shaft with respect to a controlled angular position of the control shaft and a line representing a characteristic of the biasing force of the first biasing member applied to the control shaft with respect to the controlled angular position of the control shaft are set to intersect each other at only one point.