Patent ID: 7832707
Filing Date: 2010-11-16
Classification: B60T,F16K,H01F

Abstract:
1. A normally open electromagnetic valve comprising: a fixed core, a movable core disposed so as to advance and retreat relative to the fixed core; a coil which produces a magnetic field passing through the fixed core and the movable core; a valve body disposed so as to move together with the movable core; a valve seat member comprising a funnel-shaped valve seat surface which is adapted to be brought into abutment with the valve body so as to close a flow path; a return spring for biasing the valve body so as to move apart from the valve seat surface; a raised portion formed at one of the fixed core and the movable core so as to project towards the other of the fixed core and the movable core; and a recessed portion formed at the other of the fixed core and the movable core so as to face the raised portion, wherein a relationship between the raised portion and the recessed portion is set such that while a distance therebetween is within a predetermined range, an attraction force acting between the fixed core and the movable core by virtue of an excitation force of the coil decreases as the raised portion approaches or moves into the recessed portion, and when the valve body and the valve seat surface are brought into abutment with each other by exiting the coil, the distance between the raised portion and the recessed portion stays within the predetermined range, and the funnel-shaped valve seat surface wears to a spherically shaped surface of the seal portion such that when the seal portion is brought into contact with the funnel-shaped valve seat surface, the seal portion contacts the funnel-shaped valve seat surface in a surface fashion at a smaller seal diameter D