Patent ID: 8312853

Claim:
A valve spring device which urges a valve incorporated in a port of an engine in a closing direction, the valve spring device comprising: a first coil spring located on a side of a retainer of the valve; and a second coil spring located on a side of a cylinder head and connected in series with the first coil spring, wherein: an inside diameter of the second coil spring is greater than an outside diameter of the first coil spring, a part of the first coil spring including an end portion along an axis is inserted into the second coil spring, the end portion of the first coil spring and an end portion of the second coil spring are connected to each other by a connecting member, a shaft of the valve passes within the first coil spring and the second coil spring, the first coil spring and the second coil spring are mounted between the retainer and the cylinder head and compressed to a first length and a second length, respectively, the second coil spring is compressed to be pre-loaded by being arrested by a stopper so as not to be stretched beyond the second length, only the first coil spring is compressed, to be shorter than the first length, when a lift of the valve is not higher than a predetermined value, and the second coil spring is compressed to be shorter than the second length in a state in which at least some turns of a wire of the first coil spring come into close contact with one another when the lift of the valve exceeds the predetermined value.