Patent ID: 6911884

Claim:
An electromagnetic switching device comprising: a sealed contact section including: a sealing vessel made of an insulating material; a fixed terminal provided with a fixed contact, said fixed terminal being air-tightly jointed to said sealing vessel; a movable contact piece provided with a movable contact which is rendered movable toward and away from said fixed contact; a cylindrical part with a closed bottom and made of a magnetic material for housing a movable iron core which moves said movable contact toward and away from said fixed contact; a first joint member made of a metallic material with an insertion hole formed substantially in a center thereof; a metal plate made of a non-magnetic material with a hole formed substantially in a center thereof, the hole having an inner diameter substantially the same as an inner diameter of said cylindrical part; a second joint member made of a metallic material, said second joint member being fixedly and air-tightly jointed to said sealing vessel and said first joint member; a movable shaft having one end thereof fixedly attached to said movable iron core, said movable shaft being axially movable in the insertion hole of said first joint member; a compression spring for urging said movable contact piece in such a direction as to urge said movable contact toward said fixed contact; a retainer for retaining said compression spring in a compressed and suspended state in such a manner that said movable contact piece is operatively linked to said movable shaft; and a return spring for urging said movable iron core in such a direct as to move said movable contact away from said fixed contact; and a driving section for driving said movable iron core, wherein said cylindrical part and said first joint member are air-tightly jointed each other with said metal plate provided therebetween, and said movable iron core is housed in said cylindrical part with a clearance defined by said movable iron core and said first joint member corresponding to a required stroke within which said movable contact is rendered movable toward and away from said fixed contact.