Fast-acting toggling armature uses centring spring
A translating actuator acting between two extreme positions defined by mechanical stops comprises: an armature mass movable relative to the armature body, a stiff armature spring set such that the natural resting position of the armature mass is close to the centre of travel between the two extreme positions and pair of latches with sufficient holding force that the armature mass can be held at either extreme position against the restoring force of the spring and can be released quickly relative to the natural period of vibration determined by the armature mass on the armature spring.
1 . A translating actuator acting with mechanical stops, said actuator comprising:
a valve mass movable in relation with said mechanical stops, wherein the valve mass comprises a poppet head, a valve stem, stem-to-spring interfaces and a target disc, said target disc comprising ferromagnetic material and configured to allow rapid changes in flux through axial faces of the target disc;
a valve spring acting on the valve mass, said valve spring having a resting position in relation with said mechanical stops, wherein the valve spring comprises four parallel planar springs;
a lower magnetic latch for magnetically holding the valve mass at a lower end of travel using magnetic flux driven by permanent magnet material in the lower magnetic latch;
an upper magnetic latch for magnetically holding the valve mass at an upper end of the travel using magnetic flux driven by permanent magnet material in the lower magnetic latch; and
a valve body, said valve body comprising a valve seat, a bush for maintaining alignment of the valve stem with the valve seat, and a retaining plate for the bush and body pieces, each body piece for securing said four parallel planar springs or said upper and said lower magnetic latches;
wherein each of said upper and said lower magnetic latch comprises ferromagnetic material, permanent magnet material, and a coil, said coil configured to be energised by a current to provide a magneto-motive force, wherein the magneto-motive force of the permanent magnet material opposes the magnetic force of said upper and said lower magnetic latch such that the latch is configured to release the valve mass in a time shorter than a natural period of vibration determined by the valve mass connected to the valve spring, wherein a profile of each of said upper and said lower magnetic latch comprises:
a first plateau extending away from a central axis of the actuator;
a ramp portion extending from the first plateau; and
a second plateau extending from the ramp portion, wherein thickness of the pair of latches is greater along a length of the first plateau than along a length of the second plateau.
2 . The translating actuator according to claim 1 , wherein the lower magnetic latch comprises a plurality of pole pieces and corresponding pieces of permanent magnet material.
3 . The translating actuator according to claim 2 , wherein the plurality of pole pieces of permanent magnet material are aligned with an energising coil for operating the lower magnetic latch.
4 . The translating actuator according to claim 1 , wherein the upper and lower magnetic latches are formed from a material with a high electrical resistivity.