| 摘要 |
An improved polarized electromagnetic relay comprises a base of magnetic material mounting thereon a contact assembly and an electromagnet with an armature which is pivotally supported at its end to the base and operatively connected to said contact assembly for opening and closing a relay contact. Included in the electromagnet is a pair of first and second pole members which are magnetized to opposite polarity by a permanent magnet coupled thereto and which define therebetween a magnetic gap into which the other end of the armature extends. The first pole member and the armature are magnetically coupled to the base so as to cause a magnet flux of the permanent magnet to circulate through the second pole member, the armature, the base, and the first pole member for attracting the armature to the second pole member. Upon energization of the coil, a resulting coil flux circulates through the armature, the base, and the first pole member in opposing direction to the magnet flux for attracting the armature to the first pole member. A cover of magnetic material is included to fit over the base and be magnetically coupled thereto. The second pole member is disposed adjacent to the inner wall of the cover so as to define therebetween an air gap which is cooperative with the second pole member, the armature, base, and the cover in order to circulate an additional coil flux in the opposing direction to the magnet flux across the second pole member and the armature upon energization of the coil, weakening the magnetic flux and therefore expediting the armature movement by the coil flux to thereby improve response sensitivity. |
