Electrical switch of the normally closed type

1. An electric switch ( 10 ) of the normally closed type comprising:

a casing ( 12 ) which carries a pair of fixed contact elements ( 42 ) each of which comprises a contact head ( 48 ) which delimits a front transverse fixed contact surface ( 58 ) and which is arranged inside ( 34 ) the casing ( 12 ) in such a way that the two fixed contact surfaces ( 58 ) are longitudinally aligned;

a contact bar ( 96 ), forming a movable contact, which runs transversely opposite the two fixed contact surfaces ( 58 ) and which is mounted movably, according to a horizontal longitudinal direction, between;

at least one rear closure position in which a rear contact surface ( 100 ) of the contact bar ( 96 ) is in contact bearing on the said fixed contact surfaces ( 58 ) so as to establish an electrical link between the two fixed contact elements ( 42 ) of the switch ( 10 );

and a front opening position in which the said rear contact surface ( 100 ) is offset longitudinally towards the front in such a way as to interrupt the said electrical link;

and a member ( 60 ) for actuation of the movable contact bar ( 96 ) which is mounted so as to slide longitudinally in the casing ( 12 ) between;

at least one rear rest position in which it is in abutment against a portion ( 70 ) of the casing ( 12 ) and in which the movable contact bar ( 96 ) is in its rear closure position;

and a front triggering position in which the movable contact bar ( 96 ) is in its front opening position;

the moveable contact bar ( 96 ) and the actuation member ( 60 ) constituting a movable assembly, and the switch ( 10 ) comprising a return spring ( 108 ) which co-operates with the movable contact bar ( 96 ) so as to urge it towards its rear closure position;

characterized in that the movable contact bar ( 96 ) is mounted rocking on the actuation member ( 60 , 66 , 92 ) about an upper transverse axis (A), in that the actuation member ( 60 , 72 ) comprises a front face ( 74 ) for driving the movable contact bar ( 96 ) towards which the bar is returned by the spring ( 108 ), and in that the said front drive face ( 74 ) is offset longitudinally towards the rear with respect to the contact bar ( 96 ) when the bar is in its rear closure position and when the actuation member ( 60 ) is in its rear rest position.

2. Switch according to claim 1 , characterized in that the said front drive face ( 74 ) is able to co-operate with a portion of the rear contact surface ( 100 ) of the movable contact bar ( 96 ).

3. Switch according to claim 2 , characterized in that the said portion of the rear contact surface ( 100 ) of the movable contact bar ( 96 ) is situated between two transverse end portions each of which bears on an associated fixed contact surface ( 58 ) when the bar ( 96 ) is in its rear closure position.

4. Switch according to claim 1 , characterized in that the said rear contact surface ( 100 ) is a surface in the form of an arc of a convex cylinder of transverse axis, and in that the said front fixed contact surfaces ( 58 ) are vertical plane surfaces.

5. Switch according to claim 1 , characterized in that the actuation member ( 60 ) comprises a horizontal central finger ( 76 ) for guiding the return spring ( 108 ) which runs towards the front through a corresponding notch ( 102 ) of the movable contact bar ( 96 ), and in that the return spring ( 108 ) is a spiral compression spring through which the guiding finger passes, the front longitudinal end ( 112 ) of which bears on a wall ( 16 , 17 ) of the casing, and the rear longitudinal end ( 114 ) of which bears on a front face portion ( 96 ) of the movable bar.

6. Switch according to claim 1 , characterized in that the actuation member ( 60 ) is able to occupy a so-called overtravel position which is offset longitudinally towards the front with respect to its front triggering position.

7. Switch according to claim 1 , characterized in that it exhibits a general symmetry of design with respect to a vertical and longitudinal mid plane (PVM).