Patent ID: 8156906

Claim:
A valve timing controller for adjusting a valve timing of a valve by use of a hydraulic fluid supplied from a fluid supply source, the valve being opened/closed by a camshaft which is driven by a torque transmitted from a crankshaft of an internal combustion engine, the valve timing controller comprising: a housing rotating synchronously with the crankshaft and defining a hydraulic chamber therein; a vane rotor rotating synchronously with the camshaft, the vane rotor having a vane which divides the hydraulic chamber in its rotational direction, the vane rotor varying a rotational phase of the camshaft relative to the housing with the hydraulic fluid introduced into the hydraulic chamber; a lock means having a lock chamber for locking the vane rotor relative to the housing by discharging the hydraulic fluid from the lock chamber, and for unlocking the vane rotor relative to the housing by introducing the hydraulic fluid into the lock chamber; a valve body including an operation port which communicates with the hydraulic chamber, a supply port which receives the hydraulic fluid from the fluid supply source, and a discharge port from which the hydraulic fluid is discharged; a valve member linearly moving in either of a first direction and a second direction opposite to the first direction, the valve member moving to a lock range including a stroke end in the first direction in order to fluidly connect the operation port with the supply port and fluidly connect the lock port with the discharge port, the valve member moving to a stroke range deviating from the lock range in the second direction in order to connect both of the operation port and the lock port with the supply port; a biasing means for generating a biasing force biasing the valve member in the first direction; and a driving source for generating a driving force driving the valve member in the second direction, wherein the biasing means stepwise varies the biasing force when the valve member moves to be positioned at a limit position of the stroke range which confronts the lock range.