Electro-magnetically operable device

• US 20030168112A1
• Filed: 04/01/2003
• Published: 09/11/2003
• Est. Priority Date: 07/06/2000
• Status: Active Grant

• Current Assignee: Camcon Limited
• Original Assignee: Camcon Limited
• Inventors: Wygnanski, Wladyslaw
• Granted Patent: US 6,935,373 B2
• Time in Patent Office: Days
• US Class Current: 137/625.44
• CPC Class Codes: F16K 31/0682 with an articulated or pivot armature
• CPC Class Codes: F16K 31/082 using a electromagnet and a permanent magnet
• CPC Class Codes: H01F 2007/1669 Armatures actuated by current pulse, e.g. bistable actuators
• CPC Class Codes: H01H 51/2254 Contact forms part of armature
• CPC Class Codes: Y10T 137/86847 Pivoted valve unit

Abstract

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.

Claims

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

2. A device as claimed in claim 1, 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 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 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

3. A device as claimed in claim 2, wherein a pulse of current in one direction will cause the armature assembly to move to, and remain, at one end of its travel, and a pulse of current of similar magnitude but opposite direction, will cause it to move to, and remain at, the other end of its travel.

4. A device as claimed in any of claims 1 to 3, 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.

11. A device as claimed in any of claims 1 to 10, wherein the faces of the poles are inclined so as to be parallel to the inclination of the armature portion which extends beyond the hinge point to its free end, and which by virtue of the hinging action, becomes angled relative to the fixed part of the armature.

12. A device as claimed in any of claims 1 to 11, 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 attracted to the other pole, whereby movement of the armature controls the flow of a fluid (liquid or gas) through the opening.

13. A device as claimed in claim 12, 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.

14. A device as claimed in claim 12 or 13, wherein a seal is provided around the edge of the or each opening, to be covered by the armature.

15. A device as claimed in claim 12, 13 or 14, wherein a sealing material is provided on the or each face of the armature which is to cover an opening.

16. A device as claimed in any of claims 1 to 15, 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.

17. A device as claimed in any of claims 1 to 16, 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.

18. A device as claimed in claim 17, wherein the adjustment is 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.

19. A device as claimed in any of claims 1 to 18, 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.

20. A device as claimed in any of claims 1 to 3, 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.

21. A device as claimed in claim 20, 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.

22. A device as claimed in any of claims 1 to 4, 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 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 a S pole so that it is attracted to one and repelled from the other of the two faces defining the gap.

23. A device as claimed in claim 22, 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.

24. A device as claimed in claim 22, 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

25. A device as claimed in claim 24, 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.

26. A device as claimed in claim 25, wherein at least a part of each armature is visible in a window to reveal the position it has adopted.

27. A device as claimed in claim 25 or 26, wherein each armature is marked and the marking is visible through a window.

28. A device as claimed in claim 25 or 26, wherein each armature is coloured and the colouring is visible in a window.

29. A device as claimed in claim 25, wherein at least a part of only one of the armatures is visible through a window and the position it has adopted reveals the position adopted by the other.

30. A device as claimed in claim 29, wherein the visible armature or part thereof is marked and the marking is visible through the window.

31. A device as claimed in claim 30, wherein the marking is in the form of two colours, one of which is visible when it is in one position and the other of which is visible when it occupies the other position.

32. A device as claimed in any of claims 20 to 31, 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.

33. A fluid flow control valve having at least one inlet and at least one outlet comprising an electromagnetically operated device as claimed in any of the preceding claims, 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.

34. A valve as claimed in claim 33, having one inlet and two outlets.

35. A valve as claimed in claim 33 having two inlets and one outlet.

5. A electromagnetically operated device comprising a naturally resilient magnetisable elongate armature sandwiched over part of its length between two parts of a magnetic circuit which contains an air gap into which the armature extends, and an electromagnet is provided to magnetically polarize the armature along its length to cause the end of the armature in the air gap to be attracted to one or the other of the two poles of the magnetic circuit defining the gap.

6. A device as claimed in claim 5, wherein the armature is adapted to occupy the air gap with an equal distance between it and each of the two poles when relaxed, so that if all the magnetic flux is reduced to zero the armature is equally spaced from both poles.

7. A device as claimed in claim 5 or 6, wherein closure of the gap by the movement of the armature towards one of the poles increases the flux linking the armature and that one pole, and the resilience of the armature material is selected so that the tendency of the armature to resume a mid position between the poles is less than the magnetic force acting between it and the said one pole to which it has. moved so that the armature will remain in position near or in contact with the said one pole.

8. A device as claimed in claim 7, wherein the pole to which the armature is attracted is selected by causing a direct current to flow through the electromagnet coil in one direction or the other.

9. A device as claimed in any of claims 5 to 8, wherein the armature is a straight elongate strip of steel.

10. A device as claimed in any of claims 5 to 9 in which the elongate armature hinges about a point along its length from where it protrudes from the two parts between which it is secured.

36. Electromagnetically operable devices (actuators) constructed, arranged and adapted to operate substantially as herein described and/or with reference to the accompanying drawings.

37. Electromagnetically operable fluid flow control valves constructed, arranged and adapted to operate substantially as herein described and/or with reference to the accompanying drawings.