Patent ID: 7240893

Claim:
A normally closed solenoid valve, comprising: a fixed core; a valve portion for opening and closing a flow path of a hydraulic fluid, the valve portion including a valve seat and a valve body disposed opposed to the valve seat to be seated therein; a movable core disposed between the fixed core and the valve seat; which is capable of advancing and retreating along with the valve body with respect to the valve seat; a resilient biasing member for biasing the movable core in a valve-closing direction along which the valve body is seated in the valve seat for closing the valve; and a coil for generating an attracting force between the movable core and the fixed core when energized to cause the movable core to retreat in a valve-opening direction from an initial position thereof where the valve portion is in a closed state, the attracting force acted against a biasing force exerted by the resilient biasing member; wherein, a characteristic graph line of spacing distance/attracting force that defines the attracting force in relation with a spacing distance between the fixed core and the movable core provides a slope A(N/mm) in an assembly allowance range, and the compression resiliency coefficient of the resilient biasing member is substantially the slope A(N/mm), such that the biasing force of the resilient biasing member has an oppositely directed and substantially equal force to the attracting force over the assembling allowance range, wherein the resilient biasing member is a spring member, wherein the compression resiliency coefficient is a spring constant of the spring member, and wherein the spacing distance between the fixed core and the movable core is measured in a direction of movement of the movable core.