Sealed contact device with contact gap adjustment capability

Abstract

A sealed switch has a vessel defining therein a hermetically sealed space which receives a pair of fixed contacts and a movable contact bridging the fixed contact. The movable contact is movable between an ON-position of closing with the fixed contact and an OFF-position of separating from the fixed contacts. Hydrogen gas or hydrogen rich gas is filled in the sealed space in order to suppress arc development between the movable and fixed contacts. The plunger carries at its axial one end the movable contact and carrying at the other axial end an actuator which moves the plunger axially for movement of the movable contact from the OFF-position to the ON-position. An over-travel spring is provided to give a bias for moving the movable contact relative to the plunger in order to develop a contacting pressure between the movable and fixed contacts. The over-travel spring is supported to a spring holder secured to the plunger. The plunger is formed with a threaded portion which extends through the actuator to allow the plunger to move axially relative to the actuator for adjustment of a contact gap between the movable and fixed contact, and the spring holder is formed with stopper protrusions which project in abuttable and slidable relation to the interior surface of the vessel such that the movable contact is prevented from rotating together with the plunger. Accordingly, the spring holder is best utilized to restrict the movable contact from rotating together with the actuator to enable an easy adjustment of the contact gap simply by rotating the actuator.