Switchable magnetic device

Abstract

The present invention relates to a switchable magnetic device. Additional aspects of the present invention further relate to various devices including a switchable magnetic device. In one aspect there is described a switchable magnetic device of the kind including a housing, a first permanent magnet, a second permanent magnet, the first and second permanent magnets being mounted within the housing such that the first and second magnets are rotatable relative to each other, between a “fully off” position in which the north and south poles of the first magnet are in substantial alignment with the south and north poles respectively of the second magnet such that the device presents a relatively weak external magnetic field, and a “fully on” position in which the north and south poles of the first magnet are positioned substantially in alignment with the north and south poles respectively of the second magnet such that the device presents a relatively strong external magnetic field, characterised in that biasing means are operatively associated with one or both of the first and second magnets to bias the relative rotation of said magnets toward the fully on position, and wherein placing said device on or in close proximity to a ferromagnetic material causes the first and second magnets to rotate to a relative orientation such that the device presents a relatively strong external magnetic field. The device of the first aspect of the present invention provides a switchable magnetic device that can automatically switch to an “on” position in which the device presents a relative strong external magnetic field when the device is positioned on or in close proximity to a ferromagnetic material.

1 . A switchable magnetic device of the kind including a housing, a first permanent magnet, a second permanent magnet, the first and second permanent magnets being mounted within the housing such that the first and second magnets are rotatable relative to each other, between a “fully off” position in which the north and south poles of the first magnet are in substantial alignment with the south and north poles respectively of the second magnet such that the device presents a relatively weak external magnetic field, and a “fully on” position in which the north and south poles of the first magnet are positioned substantially in alignment with the north and south poles respectively of the second magnet such that the device presents a relatively strong external magnetic field, characterised in that biasing means are operatively associated with one or both of the first and second magnets to bias the relative rotation of said magnets toward the fully on position, and wherein placing said device on or in close proximity to a ferromagnetic material causes the first and second magnets to rotate to a relative orientation such that the device presents a relatively strong external magnetic field.  
     
     
         2 . A switchable magnetic device as claimed in  claim 1  wherein in use, when said device is on or in close proximity to a ferromagnetic material the force required to cause relative rotation of the first and second magnets towards the fully on position is within a first predetermined force range, and when said device is not in contact with or in close proximity to a ferromagnetic material the force required to cause relative rotation of the first and second magnets toward the fully on position is within a second predetermined force range, said second predetermined force range having a higher peak force than said first predetermined force range, and wherein said bias means applies a rotational force to bias the relative rotation of said magnets towards the fully on position with a force exceeding the peak force of the first predetermined force range, but less than the peak force of the second predetermined force range, thereby causing the magnets to automatically rotate toward the fully on position when the device is on or in close proximity to a ferromagnetic material.  
     
     
         3 . A device as claimed in  claim 1  or  claim 2  wherein the biasing means is a spring.  
     
     
         4 . A switchable magnetic device of the kind including a housing, a first permanent magnet, a second permanent magnet, the first and second permanent magnets being mounted within the housing such that the first and second magnets are rotatable relative to each other, between a “fully off” position in which the north and south poles of the fist magnet are in substantial alignment with the south and north poles respectively of the second magnet such that the device presents a relatively weak external magnetic field, and a “fully on” position in which the north and south poles of the first magnet are positioned substantially in alignment with the north and south poles respectively of the second magnet such that the device presents a relatively strong external magnetic field, characterised in that said device further includes rotation limiting means to limit the extent of the relative rotation of the magnets.  
     
     
         5 . A switchable magnetic device of the kind including a housing, a first permanent magnet, a second peremanent magnet, the first and second permanent magnets being mounted within the housing such that the first and second magnets are rotatable relative to each other, between a “fully off” position in which the north and south poles of the first magnet are in substantial alignment with the south and north poles respectively of the second magnet such that the device presents a relatively weak external magnetic field, and a “fully on” position in which the north and south poles of the first magnet are positioned substantially in alignment with the north and south poles respectively of the second magnet such that the device presents a relatively strong external magnetic field, characterised in that relative rotation of the first and second magnets is limited such that said magnets are prevented from reaching the fully on position but said first and second magnets can be rotated to a predetermined relative orientation such that the north and south poles of the first magnet are closely but not completely aligned with respective north and south poles of the second magnet such that said device still presents a relatively strong external magnetic field and said device automatically switches to a state where the external magnetic field is relatively weak when said device is removed from contact or removed from close proximity to an external ferromagnetic material.  
     
     
         6 . A switchable magnetic device of the kind including a housing a first permanent magnet, a second permanent magnet, the first and second permanent magnets being mounted within the housing such that the first and second magnets are rotatable relative to each other between a “fully off” position in which the north and south poles of the first magnet are in substantial alignment with the south and north poles respectively of the second magnet such that the device presents a relatively weak external magnetic field, and a “fully on” position in which the north and south poles of the first magnet, are positioned substantially in alignment with the north and south poles respectively of the second magnet such that the device presents a relatively strong external magnetic field, and actuation means configured to cause relative motion of the first and second magnets, characterised in that said actuation means includes a flexible portion that deforms if the actuation means is actuated in the absence of an external magnetic circuit to thereby limit relative rotation of said magnets, said flexible portion having sufficient yield strength to substantially avoid deformation during actuation of said actuation means in the presence of an external magnetic circuit.  
     
     
         7 . A device as claimed in  claim 6  wherein said flexible portion is a spring link.  
     
     
         8 . A device as claimed in either  claim 6  or  7  wherein said flexible portion can be deformed to a maximum extent, after which continued actuation of the actuation means causes relative rotation of the magnets  
     
     
         9 . A system for controlling the orientation of a satellite in orbit around a planet having a planetary magnetic field, said system including at least one switchable magnetic device mounted to the satellite such that the orientation of the at least one switchable magnetic device can be varied relative to the satellite, wherein in use the orientation of the satellite can be changed by deflecting the magnetic axis of the switchable magnetic device relative to the direction of the planetary magnetic field when the magnets are in the second position, thereby causing the satellite to change orientation to at least partially re-align the magnetic axis of the at least one switchable magnetic device to the direction of the planetary magnetic field.  
     
     
         10 . A device for collecting ferromagnetic items, said device including a ferromagnetic collection portion configured to collect and retain ferromagnetic items by magnetic attraction therewith, and a surface engaging portion which is configured in use to engage a ferromagnetic support surface against which the device is held, said device further including at least one switchable magnetic device switchable between an “off” position in which the ferromagnetic collection portion is substantially demagnetised, and an “on” position in which the external magnetic field of the switchable magnetic device, magnetises the collection portion to collect and retain ferromagnetic articles in contact with or in close proximity to the collection portion, and holds the device against the ferromagnetic support surface by magnetic attraction.  
     
     
         11 . Clamping means adapted to clamp at least one article, said clamping means including: 
 a first clamping members;    a second clamping member slideable towards and away from the first clamping member, and spaced apart from the first member to define a gap into which an article to be clamped can be inserted; and    a switchable magnetic device mounted to or in close proximity to one of the first or second clamping member, said switchable magnetic device including actuation means for switching the switchable magnetic device off or on, whereby when the switchable magnetic device is on the first and second clamping members move towards each other thereby clamping an article inserted in the gap between the clamping members.    
     
     
         12 . A switchable magnetic device configured to operably engage one or more functional modules adapted to provide or limit functionality of the switchable magnetic device.  
     
     
         13 . A gripping device configured to grip a surface, said gripping device including at least one gripping means of the type having an evacuatable void adapted to sealably engage a surface, wherein said gripping means grips the surface by forming a suction force between the surface and the gripping means by partially evacuating the void, wherein said gripping device further includes at least one switchable magnetic device configured to produce an additional magnetic engagement with a surface when the surface is ferromagnetic.  
     
     
         14 . A coupling comprising a first magnetic device and a second magnetic device, the first magnetic device being a switchable magnetic device, said first magnetic device and said second magnetic device being arranged relative to each other such that said second magnetic device attracts the first magnetic device when the first magnetic device is off, and said second magnetic device repels said first magnetic device when said first magnetic device is on.  
     
     
         15 . A coupling means including a switchable magnetic device, and at least one second magnetic means, said switchable magnetic device and said second magnetic means being arranged relative to each other such that when the switchable magnetic device is on and the second magnetic means is in contact with or in close proximity to the switchable magnetic device, the second magnetic means is relatively strongly attracted to the switchable magnetic device to thereby couple said the second magnetic means to the switchable magnetic device, and when said switchable magnetic device is off the second magnetic means is relatively weakly attracted to the switchable magnetic device such that the second magnetic means and switchable magnetic device can be decoupled.  
     
     
         16 . A latching means including, 
 a latching member, movable between an extended position in which it can be received into a latching recess to cause latching of the latching means, and a retracted position,    a first magnetic means and a switchable magnetic device, movable relative to each other and mounted such that one of said, first magnetic means or switchable magnetic device is coupled to said latching member, such that actuation of the switchable magnetic device causes relative movement of the latching member.    
     
     
         17 . A switchable magnetic device of the kind including a housing, a first permanent magnet, a second permanent magnet, the first and second permanent magnets being mounted within the housing such that the first and second magnets are rotatable relative to each other, between an off position in which the device presents a relatively weak external magnetic field, and an on position in which the device presents a relatively strong external magnetic field, characterised in that the device further includes a low reluctance shunt mounted to at least a first portion of the housing configured to be at least partially magnetised when the device is in the off position such that the external magnetic field presented by the device adjacent to the first portion of the housing is negligible, and that the device further includes a high reluctance region between the magnets and a portion of an external surface of the device, wherein the high reluctance region has sufficient reluctance that the magnetic flux presented at said portion of the external surface of the device is substantially constant.  
     
     
         18 . A switchable magnetic device of the kind including a housing, a first permanent magnet, a second permanent magnet, the first and second permanent magnets being mounted within the housing such that the first and second magnets are rotatable relative to each other, between an off position in which the device presents a relatively weak external magnetic field, and an on position in which the device presents a relatively strong external magnetic field, characterised in that the device flier includes a low reluctance shunt configured to be at least partially magnetised when the device is in the off position such that the external magnetic field presented by the device adjacent to the shunt is negligible.  
     
     
         19 . A switchable magnetic device of the kind including a housing, a first permanent magnet a second permanent magnet, the first and second permanent magnets being mounted within the housing such that the first and second magnets are rotatable relative to each other, between an off position in which the device presents a relatively weak external magnetic field, and an on position in which the device presents a relatively strong external magnetic field, characterised in that the device further includes a high reluctance region between the magnets and a portion of an external surface of the device, wherein the high reluctance region has sufficient reluctance that the magnetic flux presented at said portion of the external surface of the device is substantially constant.  
     
     
         20 . An electrical coupling configured to make an electrical connection with an external conductor, said coupling including at least one contact portion configured to make the electrical connection, and a switchable magnetic device configured to retain the contact portion in conductive contact with the external conductor when the switchable magnetic device is in the on position.  
     
     
         21 . A switchable magnetic device of the kind including a housing, a first permanent magnet, a second permanent magnet, the first and second permanent magnets being mounted within the housing such that the first and second magnets are rotatable relative to each other, between an off position in which the device presents a relatively weak external magnetic field, and an on position in which the device presents a relatively strong external magnetic field, characterised in that the relative orientation of the first and second magnets can be varied between the on and off positions to produce an external magnetic field of varying strength.  
     
     
         22 . A particle deflection means adapted to deflect charged particles moving past the deflection means, said deflection means including a switchable magnetic device configured to generate an external magnetic field to deflect said particles.  
     
     
         23 . A fluid coupling configured to make an fluid connection between a first fluid port and second fluid port, characterised in that said fluid coupling further includes at least one switchable magnetic device configured to retain the fluid ports in fluid communication with each other when the switchable magnetic device is in the on position.  
     
     
         24 . A suspension device having a first member suspended relative to a second member of the type including a first magnetic means associated with the first member and second magnetic means associated with the second member, characterised in that either said first or second magnetic means includes a switchable magnetic device.  
     
     
         25 . A magnetic bring means of the kind in which the motion of a conductive member relative to a magnetic means can be decreased by application of a magnetic force to the conductive member, characterised in that the magnetic means includes a switchable magnetic device.