Electromagnetic contactor

An electromagnetic contactor comprising:

• an electromagnetic block including an armature having a plunger part and a pole-contacting member mounted on only one end of said plunger part, a bobbin carrying a coil wound thereon and having an axial through-hole in which said plunger part of said armature is inserted for axial displacement, an inner yoke extending around a peripheral portion of said coil and having a first end portion opposing said pole-contacting member of sid armature, an outer yoke having a second end portion opposing said first end portion of said inner yoke for restricting said displacement of said pole-contacting member of said armature and a second end portion extending toward said plunger part of the armature, and a permanent magnet interposed between said inner and outer yoke,
• a coupling means coupled to said armature of said electromagnetic block for being displaceable therewith,
• a contact block including a group of stationary contacts, and a group of movable contacts coupled to said coupling means for making and breaking contact with said stationary contacts in response to said axial displacement of said armature,
• the contacts of one of said groups being spring loaded,
• the contacts of one of said groups having curved contact surfaces,
• the contacts of one of said groups being disposed in an inclined position prior to engagement with the contacts of the other group and arranged such that the contact surfaces of said inclined contacts perform a rolling motion along the contact surfaces of the other contacts following initial engagement between said groups of contacts, and
• depressing means engageable with said inclined contacts for inducing said rolling motion.

An electromagnetic contact comprising:

• an electromagnetic block including an armature having a plunger part and a pole-contacting member on only one end of said plunger part, a bobbin carrying a coil wound thereon and having an axial through-hole in which said plunger part of said armature is inserted for axial displacement, an inner yoke extending around a peripheral portion of said coil and including a first end portion opposing said pole-contacting member of said armature, an outer yoke having a second end portion opposing said first end portion of said inner yoke for restricting said displacement of said pole-contacting member of said armature and a third end portion extending toward said plunger part of the armature, and a permanent magnet interposed between said inner and outer yokes,
• a coupling means coupled to said armature of said electromagnetic block for being displaceable therewith,
• a contact block including a group of stationary contacts and a group of movable contacts, said group of movable contacts being coupled to said coupling means for making and breaking contact with said stationary contacts in response to said displacement of said armature, the contacts of one of said groups being spring loaded, and
• adjusting means for adjusting the position of said electromagnetic block relative to said contact block in order to delay or advance the timing when the movable contacts are displaced in response to displacement of said armature.