In a conventional electromagnetic relay described in JP-A-2008-226547, two fixed contact supports having two fixed contacts respectively are positioned, and two movable contacts are contacted by and separated from the two fixed contacts by moving one movable body, to which the two movable contacts are fixed, so that an electrical circuit is opened and closed. More specifically, the electromagnetic relay includes a movable member driven by electromagnetic force of a coil, a pressure spring for urging the movable body such that the movable contacts contact the fixed contacts, a return spring for urging the movable body via the movable member such that the movable contacts are separated from the fixed contacts, and the like. Further, a contact surface between the movable contacts and the fixed contacts is a spherical surface.
When the coil is energized, the movable member is driven toward a side away from the movable body by the electromagnetic force, and the movable body is urged by the pressure spring to be moved. As a result, the movable contacts contact the fixed contacts, and the movable member is separated from the movable body.
In a conventional electromagnetic relay described in JP-A-62-51126, two fixed contact supports having two fixed contacts respectively are positioned, and two movable contacts are contacted by and separated from the two fixed contacts by moving one movable body, to which the two movable contacts are fixed, so that an electrical circuit is opened and closed. More specifically, the movable body is integrated with a movable member that is driven by electromagnetic force of a coil such that the movable body can be relatively moved, the movable body is held at a predetermined position of the movable member by a pressure spring, and the movable member and the movable body are urged by a return spring such that the movable contacts are separated from the fixed contacts. Further, a contact surface between the movable contacts and the fixed contacts is a spherical surface.
When the coil is energized, the movable member and the movable body are driven by the electromagnetic force and the movable contacts contact the fixed contacts. At this time, the pressure spring is bent by a stroke of the movement of the movable member after the movable contacts contact the fixed contacts, thereby the movable member and the movable body are relatively moved.
However, in the electromagnetic relay described in JP-A-2008-226547, because the contact surface is a spherical surface, the movable contacts contact the fixed contacts by point contact. When the coil is energized, the movable contacts contact the fixed contacts by two-points contact, that is, at a first contact portion between one fixed contact and one movable contact, and a second contact portion between the other fixed contact and the other movable contact. In this manner, because the movable contacts contact the fixed contacts by the point contact, i.e., the two-points contact, the movable body may vibrate around a line passing through the first and second contact portions when the movable contacts collide with the fixed contacts. In particular, in the electromagnetic relay described in JP-A-2008-226547, because the movable member is separated from the movable body when the movable contacts contact the fixed contacts, the vibration suppression effect by the movable member cannot be obtained, and thereby it becomes difficult to suppress the vibration of the movable body. Thus, the vibration of the movable body may be resonated in a casing to generate abnormal noise.
In the electromagnetic relay described in JP-A-62-51126, because the movable body is integrated with the movable member, it is easy to suppress vibration of the movable body when the movable contacts collide with the fixed contacts. However, a position of a contact portion is changed in accordance with the vibration of the movable body until the vibration of the movable body is suppressed. Thus, a resistance value between the contacts is changed, and thereby it becomes easy for the contact portion to generate heat and the wear-and-tear of the contacts may occur.