초록 ▼

An electro-magnetically operated device is described in which a magnetisable armature, typically a length of thin naturally resilient mild steel, is sandwiched between, and extends from, two parts of a magentic circuit which contains an air gap into which the armature extends. An electromagnet polar

An electro-magnetically operated device is described in which a magnetisable armature, typically a length of thin naturally resilient mild steel, is sandwiched between, and extends from, two parts of a magentic circuit which contains an air gap into which the armature extends. An electromagnet polarizes the armature along its length so as to cause the end thereof in the air gap to be attached to one or the other of the two poles of the magnetic circuit defining the gap. The armature is designed so as to be capable of adopting a mid-position between the poles of the air gap if the curent flowing in the electromagnet is reduced to zero. Equalising the air gaps and adjusting the size of the gap relative to the resilience of the armature will produce a bistable characteristic in which the armature will not remain in the mid-position, but will always remain in contact with one pole or the other, and is shifted from one to the other by a pulse of current of appropriate polarity. Adjustment of the size of the air gap on one side or the other of the armature introduces an out of balance in the magnetic circuit enabling the device to adopt a monostable characteristic instead of a bistable characteristic.

대표청구항 ▼

1. An electromagnetically operable device comprising:(a) a magnetic circuit having permanent N and S poles defining an air gap; (b) an armature assembly which extends into the air gap and at least a portion of which is magnetisable and is movable between two end positions adjacent the two permanent

1. An electromagnetically operable device comprising:(a) a magnetic circuit having permanent N and S poles defining an air gap; (b) an armature assembly which extends into the air gap and at least a portion of which is magnetisable and is movable between two end positions adjacent the two permanent poles through an intermediate position towards which it is resiliently biased; (and) (c) an electromagnet which when energised by an electric current polarises the magnetisable portion of the armature assembly so that the part thereof in the air gap becomes a S or N pole and will thereby be attracted towards, one of the permanent poles, and (d) two springs each of which extends between the armature and one of the two permanent poles, which in the absence of other forces would position the armature in its said intermediate position; wherein the residual permanent flux linking the magnetic part of the armature assembly and the relevant adjacent permanent pole after a current of a given magnitude and direction has flowed in the electromagnet and displaced the armature, is sufficient to generate a force of attraction which is greater than the resilient spring force acting to return the armature to its intermediate position so as to retain the armature in its displaced position, but which is less than the sum of the resilient spring force and the force of attraction created by the magnetic flux linking the magnetic part of the armature assembly and the other permanent pole, when a similar current, but flowing in the opposite direction, flows in the electromagnet, so as to impart a bistable characteristic to the device. 2. A device as claimed in claim 1, wherein the armature assembly is formed in part from a length of resilient material and the resilient force is generated by deflecting the resilient material from an undeflected condition, to one side or the other.3. A device as claimed in claim 1, wherein an opening is provided in at least one of the poles which is covered by the armature when the latter is attracted to it, and opened when the armature either occupies its intermediate position or is attached to the other pole, whereby movement of the armature controls the flow of a fluid (liquid or gas) through the opening.4. A device as claimed in claim 3, wherein there is also an opening in the other pole, and this other opening is covered by the armature when it is attracted to this said other pole.5. A device as claimed in claim 1, further comprising a device for increasing the air gap between the armature and one of the pole faces, so that when a current flows through the electromagnet which would have attracted the armature to that pole, the residual flux linking the armature and that pole is insufficient to overcome the resilient biasing of the armature so that the armature is only attracted to that pole while the current flows.6. A device as claimed in claim 1, wherein the size of the air gap between the armature and each of the poles is adjustable to enable the balance of the magnetic circuit to be adjusted, as by way of a movable insert which may be magnetisable and which can be adjusted so as to protrude to a greater or lesser extent from a pole face.7. A device as claimed in claim 1, adapted to be linked to a parameter sensing device, which is adapted to adjust the position of one pole or a part thereof relative to the mid position of the armature, so as to increase the distance between the armature and that pole if the parameter sensed by the sensing device exceeds a predetermined value.8. A device as claimed in claim 1, wherein the armature assembly is slidable in a guide between the two end positions it can adopt depending on the direction in which the current last flowed in the electromagnet, and the latter has a core which is magnetically coupled to the magnetisable part of the armature assembly.9. A device as claimed in claim 8, wherein the core extends into the air gap between the permanent N and S poles and at least in part surrounds a movable and magnetisable part of the armature assembly.10. A device as claimed in claim 8, wherein movement of the or each armature assembly (or part thereof) covers or uncovers openings, so as to permit or impede a fluid flow, to thereby form a fluid flow control valve.11. A fluid flow control valve having at least one inlet and at least one outlet comprising an electromagnetically operated device as claimed in claim 1, wherein the movable armature acts on or comprises at least part of a movable device for controlling the flow of fluid from the inlet to the outlet.12. A valve is claimed in claim 11, having one inlet and two outlets, or two inlets and one outlet.13. An electromagnetically operable device comprising:(a) a magnetic circuit having permanent N and S poles defining an air gap; (b) an armature assembly which extends into the air gap and at least a portion of which is magnetisable and is movable between two end positions adjacent the two permanent poles through an intermediate position towards which it is resiliently biased; and (c) an electromagnet which when energised by an electric current polarises the magnetisable portion of the armature assembly so that the part thereof in the air gap becomes a S or N pole and will thereby be attracted towards one of the permanent poles, wherein the armature assembly comprises a wedge of magnetisable material which is located in a V-shaped gap between two faces of magnetisable material which are permanently magnetised as N and S poles, the included angle of the armature wedge being less than the angle between the two faces of the V-shaped gap, so that the armature can rock in the gap between two end positions, one in which it engages a face at one end of the gap and the other in which it engages a face at the other end of the gap, (a) spring means acts on the wedge to bias it into a mid-position between the two faces, and the electromagnet is coupled to the armature to cause the armature to become a N or S pole so that it is attracted to one and repelled from the other of the two faces defining the gap. 14. A device as claimed in claim 13, wherein two permanent magnets are arranged in series with a block of magnetisable material sandwiched between the inboard N pole of one and the inboard S pole of the other, and pole pieces extend from the outboard S pole of the one, and the outboard N pole of the other magnet, to define the S and N poles of the gap, and the electromagnet generates a flux which links the block of magnetisable material between the two magnets and the wedge shaped armature.15. A device is claimed in claim 13, wherein a single permanent magnet is employed, arranged transversely and symmetrically relative to the mid-position of the armature wedge, with pole pieces extending therefrom to define the V-shaped air gap, and the electromagnet is arranged with its magnetic axis transverse to that of the permanent magnet.16. A device as claimed in claim 15, wherein pole pieces are arranged to extend symmetrically in opposite directions from the ends of the single permanent magnet, to define two V-shaped air gaps, back to back, on opposite sides of the permanent magnet, and two wedge shaped armatures are provided, one in each gap and each pivotable in the gap as described above, and the electromagnet has pole pieces which influence the two armatures so that if one is a N pole the other will comprise a S pole.