Sealed contact device with contact gap adjustment capability

A sealed contact device, comprising:

• a vessel defining therein a hermetically sealed space having a length, a width and a depth, said vessel including a bottom-open case of an electrically insulative material, a metal-made barrel, and a closure plate, said barrel having one axial end sealed to said case around a bottom opening thereof and having the other axial end sealed to said closure plate;
• a pair of fixed contacts accommodated within said sealed space in a spaced relation along said length of said sealed space, said fixed contacts being electrically connected respectively to a pair of terminals provided on the exterior of said vessel;
• a movable contact accommodated within said sealed space and extending along said length thereof to bridge said fixed contacts, said movable contact being movable between an ON-position where said movable contact comes into contact simultaneously with said fixed contacts at opposite ends of said movable contact and an OFF-position where said movable contact is kept away from said fixed contacts;
• one of a hydrogen gas and a hydrogen-rich gas filled in said sealed space;
• a sleeve fixed to said closure plate and having a bore;
• a plunger extending through the bore of said sleeve so as to be slidable along its axis relative to said sleeve, said plunger carrying at its axial one end said movable contact and carrying at the other axial end an actuator, said actuator being held together with a portion of said sleeve within a top-open and bottom-closed cylinder with said sleeve disposed adjacent to a top opening of said cylinder and with said actuator disposed adjacent to a bottom of said cylinder;
• drive means which acts on said actuator to drive said plunger axially for movement of said movable contact from said OFF-position to said ON-position;
• a return spring which biases said plunger in a direction of moving said movable contact towards said OFF-position;
• and
• an over-travel spring which biases said movable contact to move relative to said plunger so as to develop a contacting pressure between said movable contact and said fixed contacts, said over-travel spring being supported to a spring holder carried on said plunger,
• wherein said plunger is formed with a threaded portion which extends through said actuator in threaded engagement therewith to allow said plunger to move axially relative to said actuator for adjustment of a contact gap between said movable contact in said OFF-position and said fixed contacts, and
• wherein said spring holder is formed with stopper protrusions which project in the width direction of said sealed space in abuttable and slidable relation to the interior surface of said vessel such that said movable contact is prevented from rotating together with said plunger relative to the actuator.