Miniature circuit breaker is disclosed with a latch for continuously opening and closing a contact point with a contact lever on which the moving contact member is molded. A toggle lever gear with a link connected to a switching handle and a coupling element are provided, the coupling element connecting the link with the contact lever, which toggle lever gear can be brought from a first stable position (switched-on position) into a second stable position via a dead-center position by a tripping mechanism. The contact lever can be rotated and the contact point can be permanently opened. A compression spring is provided which acts on the link, the force of which acts approximately in a direction of the longitudinal extent of the link in the switched-off position, and thus at the beginning of the switching-on process, and transversely thereto in the switched-on position.

Miniature circuit breaker with a latch is known per se. The latch comprises a toggle lever gear which has a link which is in each case connected in an articulated manner with a switching handle and a coupling element; the coupling elementconnects the link with the contact lever also in an articulated manner. In the switched-on state, the gear is in a first stable position from which the gear can be brought into a second stable position via a dead-center position by means of a trippingmechanism; in this second position, the contact lever is rotated in the switched-off direction and the contact point is permanently opened. The tripping mechanism used could be an electromagnetic or thermal trip, the latter in the form of a thermalbimetallic strip or a strip of a shape-memory alloy.

So that the toggle lever gear can be moved from its first stable position to its second stable position, a specific force is applied which essentially depends on the force with which the coupling element acts on the contact lever.

In an exemplary embodiment, a compression spring is provided which acts on a link and the force of which acts approximately in a direction of the longitudinal extent of the link in the switched-off position, and thus at the beginning of theswitching-on process, and transversely thereto in the switched-on position.

In a particularly advantageous embodiment, the compression spring can be a helical spring supported on the switching handle, with a molded-on, radially protruding arm which rests elastically against the link.

At the end at the switching toggle, an approximately circular-arc-shaped cam interacting with the elastic arm can be arranged in an exemplary embodiment, with this cam face being molded on at a head in accordance with a further embodiment; in theswitched-off position, the arm is located outside the cam face and during the switching-on process, it slides into the area of the cam face.

According to a further advantageous embodiment, the head can have an approximately triangular shape, the center axis or center line of the head extending transversely to the link, in such a manner that the elastic arm exerts a first force on thelink in the switched-off state and a second force in the switched-on state, the first force extending at a distance from the pivot axis of the link at the switching handle and the second force extending transversely to the longitudinal extent of the linkthrough the pivot point.