Linear push plunger electrical switch with tubular shroud arc prevention means

Claim 1

In a compact electrical switch comprising a tubular housing of insulating material and defining an internal cavity having a longitudinal axis, two fixed contacts at opposite sides of said axis respectively and facing one end of said cavity, a moving contact bridge between said contacts and said end and movable in an axial direction in said cavity, said bridge having contacts thereon aligned with and bearing against the respective fixed contacts, and switch actuator means operatively associated with said bridge for moving said bridge in an axial direction to move the bridge contacts away from the fixed contacts, the improvement wherein said actuator means comprises: a coil spring coaxial with said axis and, when compressed, urging said bridge in the direction of said one end of the cavity; and a pressure member coaxial with said axis and having an axial chamber within which at least a part of the spring is received with the pressure member forming a skirt about said chamber, said pressure member being an insulating material, said skirt being positioned between said fixed contacts and about the portion of the spring between the fixed contacts when the bridge contacts are against the fixed contacts whereby as said bridge moves toward said one end and the bridge contacts are separating from the fixed contacts, that part of the spring that is diametrically between the contacts is shrouded by said pressure member thereby reducing the possibility that an arc will occur between the fixed contacts; said pressure member contacting said bridge, said chamber facing said one end of the cavity, said housing closing said one end of said cavity with the spring being between said one end and the pressure member, means defining an axial stud at the other side of the bridge, a plunger at the other end of the housing and movable axially in the housing, the portion of the plunger adjacent said other side of the bridge beiNg an insulator and defining a second chamber facing the bridge, a second coil spring in said second chamber and in compression between the plunger and the bridge, said second spring having a portion encircling said stud, said second spring being weaker than the spring contacting said pressure member, and a second pair of fixed contacts between the bridge and the other end of the cavity and on opposite sides of the axis respectively, said bridge having contacts thereon facing said second pair of fixed contacts.