Patent ID: 7895980

Claim:
A valve timing adjusting device for an internal combustion engine, wherein the valve timing adjusting device is provided in a driving force transmission system of the engine, which transmits a driving force from a drive shaft to a driven shaft for opening and closing at least one of an intake valve and an exhaust valve, wherein the valve timing adjusting device adjusts timing of opening and closing the at least one of the intake valve and the exhaust valve, the valve timing adjusting device comprising: a housing that is rotatable together with one of the drive shaft and the driven shaft, wherein the housing defines a plurality of receiving chambers therein, each of which is circumferentially defined within a given angular range; a first vane rotor that is rotatable together with the other one of the drive shaft and the driven shaft, wherein: the first vane rotor partitions a first one of the plurality of receiving chambers into a first retard chamber and a first advance chamber; and the first vane rotor is rotatable relatively to the housing in a retard direction and an advance direction, which is opposite to the retard direction, by pressure of working fluid supplied to the first retard chamber and the first advance chamber; a second vane rotor that is positioned coaxially with the first vane rotor, wherein: the second vane rotor is rotatable relatively to the drive shaft and the driven shaft; the second vane rotor partitions a second one of the plurality of receiving chambers into a second retard chamber and a second advance chamber; and the second vane rotor is rotatable relatively to the housing in the retard direction and the advance direction by pressure of working fluid supplied to the second retard chamber and the second advance chamber; a biasing device that has a first end engaged with the first vane rotor and a second end engaged with the second vane rotor, wherein: the biasing device biases one of the first vane rotor and the second vane rotor in the advance direction; and the biasing device biases the other one of the first vane rotor and the second vane rotor in the retard direction; and a limiting device that allows the first vane rotor to rotate relative to the second vane rotor when pressure of working fluid supplied from an external fluid supplier is lower than a preset level, wherein the limiting device limits the first vane rotor from rotating relative to the second vane rotor when the pressure of working fluid supplied from the fluid supplier is equal to or higher than the preset level.