Patent ID: 8228149

Claim:
An electromagnetic control mechanism ( 1 ) comprising: first and second coils ( 3 , 4 ) each being supported by a respective first and second yokes ( 5 , 6 ) at axially opposite ends of and within a cylindrical tube ( 2 ), each of the first and the second yokes ( 5 , 6 ) having an opening ( 5 a , 6 a ) which is coaxially aligned with and supports an axially slidable actuating element ( 15 ), a single permanent magnet ( 8 ) being fixed to the actuating element ( 15 ) between two flux-conducting plates ( 9 , 10 ) and two plunger armatures ( 13 , 14 ), each of the two flux-conducting plates ( 9 , 10 ) being coupled to and radially extending from a respective one of the two plunger armatures ( 13 , 14 ) with the permanent magnet ( 8 ) being sandwiched therebetween, a holding pole ( 16 ) being fixed to and located within the tube ( 2 ) between the axially opposite ends thereof, the first and the second yokes ( 5 , 6 ), the holding pole ( 16 ) and the permanent magnet ( 8 ) being axially located between and axially separating and spacing the first coil ( 3 ) from the second coil ( 4 ), the actuating element ( 15 ) being axially slidable between a first stable end position, in which the permanent magnet ( 8 ) is axially fixed adjacent the first yoke ( 5 ), and a second stable end position, in which the permanent magnet ( 8 ) is axially fixed adjacent the second yoke ( 6 ), depending on variable interaction between a magnetic flux of the permanent magnet ( 8 ) and magnetic fields ( 3 a , 3 b , 4 a , 4 b ) of the first and the second coils ( 3 , 4 ), and the actuating element ( 15 ) being fixable in a third axially centrally located stable position, between the first and the second end positions, by a closed magnetic circuit formed by the permanent magnet ( 8 ), the flux-conducting plates ( 9 , 10 ) and the holding pole ( 16 ).