Patent ID: 7707982

Claim:
A valve rotating mechanism for an exhaust valve, the mechanism comprising: a first helical gear disposed on a rotary cylinder, the rotary cylinder being linked to a valve stem via a freewheel device, the freewheel device transmitting rotation of the valve stem during a closing movement of the valve stem; a second helical gear disposed on a support cylinder, the support cylinder being fixed to a housing of the exhaust valve; wherein the first and second helical gears engage to rotate the valve stem relative to the support cylinder; wherein the first helical gear comprises a first gear length along a longitudinal axis of the valve stem, the first gear length comprising the minimum engagement length of the rotary and support cylinders; and wherein the second helical gear comprises a second gear length along the longitudinal axis of the valve stem, the second gear length comprising a stroke length of the valve stem during an opening movement and the minimum engagement length of the rotary and support cylinders.