| 摘要 |
An electromagnetic actuator comprises an armature 21 and first and second coils 30, 31 formed around a common axis, which are spaced apart along the said axis. Each of the coils 30, 31 has respective pole pieces. The actuator is arranged such that on activation of the first and/or second coils 30, 31 the armature 21 will move between separate first and second axial positions. A permanent magnet 36 is arranged to latch the armature 21 in one of the first and/or second axial positions. The armature 21 may be a disc of ferromagnetic material and the coils 30,31 may be supported in respective coil holders 18, 19 which may be received in an outer housing. Each coil holder 18, 19 may be cylindrical in shape with an annular recess to receive a coil and a bore 37 within the coil recess which may support a permanent magnet 36 at a surface facing the armature 21. The coil holders 18, 19 may be made or ferromagnetic material. Threaded axial armature-position adjustment means and spring biasing means are also described. The actuator may be used to operate a valve 50. |
