Electro-mechanical latch relay

A mechanical latch relay activated by a latch current pulse, comprising:

• a casing (60), connectable to a current source, the casing including a bottom, a plurality of side walls and a cover (65) forming a generally closed cavity;
• at least two metal plates (61) extending from the bottom for connecting to an external circuit, each metal plate including a contact element (62) extending into the casing cavity;
• a generally cylindrical housing forming a cavity (70), the housing cavity open to the casing cavity, the housing cavity including side grooves about the interior wall thereof;
• a electromagnetic generating unit for generating an electromagnetic field positioned within said casing cavity, said electromagnetic generating unit including a coil (100) with a central bore (12) co-axial with the housing cavity;
• a connecting means movable axially to and from a position in which it contacts the said contact elements (62);
• a locking means within said casing, said locking means comprising a locking component (40) and a clamping part (30) including clamping tabs (32);
• said locking component (40) being a cylinder provided with teeth (41) at one end thereof for engaging with said clamping tabs (32) and a gear (42) on the periphery of the cylinder positioned within side grooves (71, 72) of said cavity (70);
• said clamping tabs (32) so engaging said teeth (41) and the side grooves (71, 72) of the cavity (70) that axial reciprocation of the locking component (40) causes indexed rotation of the clamping part (30) between positions in which the connecting means (20) contacts and does not contact the contact elements (62);
• and a coil spring (90) pressing the clamping part (30) into the side grooves (71, 72) of the cavity (70);
• characterised in that
• the generally cylindrical housing extends from a center of the said bottom of the casing (60);
• the connecting means includes a connecting plate (20) disposed between the electromagnetic generating unit and the housing and having a bolt (25) on a first side of said connecting plate and a columnar shaft (22) on the second side of said connecting plate (20), the columnar shaft (22) positioned within the central bore (12) of the coil (100);
• the coil spring (90) is positioned within the central bore (12) of the coil (100) and around the columnar shaft (22) and a second spring (50), weaker than the coil spring (90), is positioned in the housing cavity (70) and presses the locking component (40) against the clamping part (30);
• and
• the connecting means (20) is pressed by the said coil spring (90) towards the position in which the connecting plate (20) contacts the said contact elements (62), and is moved away from that position by magnetic force attraction when the electromagnetic generating unit is activated.