Abstract:
Device for levitation of an item over an optimized base by means of permanent magnets. The equilibrium is stable along one or two axes by means of these permanent magnets, and along the one or two others by means of a combination of electromagnets of near zero consumption at equilibrium.

Description:
FIELD OF THE INVENTION 
       [0001]    The invention relates to the principle and the realization of a magnetic levitation device for various items, without overturn of said device. 
         [0002]    This device is applicable to items of decoration, advertising communication, or with industrial applications that require the levitation of an item. 
       BACKGROUND INFORMATION 
       [0003]    The state of the art for levitation devices comprises items in magnetic lift such as to globes. These devices comprise a magnet at their top (at the North Pole for a globe) and are suspended under a magnet; wherein an electromagnet controls the levitating objects attraction in order to maintain a constant distance between item and the holder. These conventional systems control the electromagnet through the measurement of the magnetic field produced by the item at the level of the holder. The field at the level of the holder is measured by means of a Hall Effect sensor that delivers a tension proportional to the measured magnetic field. 
         [0004]    The PCT IB 2006004040 from the same inventor describes a way to realised levitation according to this specification:
   the levitating item is not suspended under a magnetic device but levitates over a base that comprises sources for the magnetic field.   the levitating item can be heavy. The levitation process is also completely quiet. The surface above which the item levitates is flat or at least regular. The space between the surface and the item is free and empty of any device. The arrangement implemented for the levitation is discreet or even not perceivable. The levitating item is also stable concerning turn-over.   the levitating item is in rotation around the vertical or tilted axis, free or maintained. The levitation consumes little energy, or is permanent or at least autonomous (i.e. power supply independent) over a long time duration.   
 
         [0008]    The industrial application of this patent present defects and over cost that:
       Forbid to operate this invention in the mass market for decoration and toy.   Forbid to operate it for large dimensions for art; industry and advertisement.       
 
         [0011]    The main defects are:
       the weight of the base, the weight of the levitated magnet and the thickness of the base.   the power requested to set up the levitated item and the average power requested for permanent rotation of the levitating item.       
 
         [0014]    And as a consequence of all this, the cost of this solution is affected by the cost of the base magnet; of the levitated magnet; and of the power supply. 
         [0015]    The operation of the invention PCT IB 2006004040 of the same inventor demonstrates the following characteristics for some example of dimensions: 
         [0000]    
       
         
               
               
               
               
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
               
               
               
             
           
               
                   
               
               
                   
                   
                   
                   
                   
                   
                   
                   
                   
                   
                 for 
                 for 
               
               
                   
                   
                   
                   
                   
                 base 
                 globe 
                 Levitated 
                 set up 
                 set up 
                 turning 
                 turning 
               
               
                 D 
                   
                   
                   
                   
                 weight 
                 size 
                 weight 
                 one axe 
                 2 axes  
                 one axe 
                 2 axes 
               
               
                 mm 
                 d 
                 E 
                 E′  
                 h 
                 g 
                 mm 
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                 W 
                 W 
                 W 
                 W 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 90 
                 45 
                 20 
                 40 
                 25 
                 800 
                 100 
                 60 
                 12 
                 18 
                 4 
                 5 
               
               
                 120 
                 60 
                 25 
                 40 
                 30 
                 1600 
                 140 
                 120 
                 18 
                 27 
                 4 
                 6 
               
               
                 180 
                 90 
                 25 
                 50 
                 45 
                 3600 
                 200 
                 400 
                 18 
                 27 
                 4 
                 6 
               
               
                   
               
             
          
         
       
     
         [0016]      FIG. 1  describes this. It is based on a ring ferrite magnet  11  with external diameter D; internal diameter d; thickness E, with 2 flat rings iron  14 , almost 2 iron cores  12  and copper coil  13 , 2 levitated neodymium iron bore magnets  17  and  18 , and 2 hall effect sensors  15  and  16 . E′ represents the overall thickness of the levitator&#39;s base. 
         [0017]    According to the invention, and due to its central position; the sensor  15  detects the position of the levitating magnets  17  and  18  but not the field of the coils  12 ,  13 . Then sensor  15  drives an electronic slave system that&#39;s compensates the horizontal instability. 
         [0018]    According to another version of the invention, 2 coils  12 ,  13  may be replaced with 2 magnets  19 , this stabilises one of the 2 instable horizontal axes. 
         [0019]    According to the invention the sensors  15  detects the horizontal contribution of the magnetic field emitted by the levitating magnet. This contribution is proportional to the drift of the levitating magnet over the base. The electronic slave system drives a current in the coils  13  in order to pull back the magnet  17 ,  18  over the centre; where the horizontal contribution of the magnetic field is null. 
         [0020]    The experience demonstrates that the levitation distance and the control of the levitation is optimised in respect with a few relations:
       d=D/2; E=D/10 e=E/2   then the levitation distance and control reaches h=D/4       
 
         [0023]    In fact if E increases; then the levitation distance h is reduced. If e is increased, then the levitation distance h is reduced. 
         [0024]    For this distance of levitation, the experience demonstrates that the requested power for setting up the levitating magnets over the base is almost the same what ever is the size of the base. Only the choice of 2 coils and 2 magnets or 4 coils has an influence. The magnetism and electromagnetism compared to weight is independent of the scale. Magnetic forces divided by weight is a number with no specific unit, means this ration is not dependant of the scale. 
         [0025]    By the same, the power requested to set up the levitation is not dependant of the scale. 
         [0026]    The consequence of this is: 
         [0027]    The price of the solution is almost proportional to D 3  for big devices. Means the quantity of material used for the magnets and the coils.
   And for small device the price depends also from D 3  but also from the price of the power supply and the price of the electronic board.   
 
         [0029]    The best price of Neodymium Iron Bore magnet is 0.2 Usd per cm 3 . The best price of the ferrite magnet is around 0.5 cent USD per cm 3  .
   The best price of copper for the copper is 9 USD per kg;   
 
         [0031]    For example, the cost for D=180 mm and 4 coils is 3.5 Usd for ferrite magnet, 3 Usd for copper; 12 Usd for neodymium iron bore magnet, and 3 Usd for switching power supply able to deliver 27 W during a short time; 1.4 USD for electronic board. 
         [0032]    This means almost 23.5 USD for basic bill of material not including structure and wires and all accessories. 
         [0033]    For a small one axe stabilised D=90 mm; the ring ferrite magnet is 0.3 Usd; the 2 copper coils are 0.52 Usd; 2.2 Usd for neodymium iron bore magnets and 3 Usd for switching power supply able to deliver 27 W during a short time; 0.7 USD for electronic board. 
         [0034]    This means around 6.5 USD for the basic bill of material. 
         [0035]    For a small 2 axe stabilised D=90 mm; the ring ferrite magnet is 0.3 Usd; the 2 copper coils are 1 Usd; 1.6 Usd for neodymium iron bore magnets and 3 Usd for switching power supply able to deliver 27 W during a short time; 1.4 USD for electronic board. 
         [0036]    This means around 7.3 USD for the basic bill of material. 
         [0037]    Of course these costs are given as a comparison but not as a reference. 
     
    
     DESCRIPTION OF THE INVENTION 
       [0038]    According to the invention  FIG. 2  the price of the levitating item is optimised thanks to the use of a combination of a magnet  21  and a pure Iron or magnetic Iron alloy like an iron silicon disk  22 . 
         [0039]    According to the invention the optimised thickness of the iron is near e/2. 
         [0040]    The cost or iron is near a tens of the cost of the magnet; in consequence the combination of the magnet and the iron has a cost that represent 0.6 of the cost of a magnet only solution. 
         [0041]    For example, for a levitating device with D=180 mm; the cost is immediately and significantly reduced of 5 USD. 
         [0042]    The iron represents a shortcut for the magnetic field, or a mirror.
   Two magnets  17  and  18  stick together emit the same magnetic field as one only stick under a bigger iron disk.   
 
         [0044]    According to the invention;  FIG. 3 , an iron plate  37  realises a magnetic mirror for the magnet  31 ; the and the coil and core  31  and  32 . 
         [0045]    The optimised iron plate thickness is around E/10; and it is made in pure iron, or special magnetic iron alloy like iron silicon. 
         [0046]    According to the invention; the iron plate  37  does not realise a mirror for the magnetic lines that reach the sensor  35  and  36 . In fact the magnetic fields direction is fixed perpendicular to the surface of the mirror.
   This means the tangential magnetic field is cancelled at the surface of a magnetic mirror.   
 
         [0048]    According to the invention the levitating magnet position is detected thanks to the horizontal contribution of the magnetic field by the sensor  15  or  35 . 
         [0049]    According to the invention there is no magnetic minor around the sensor  35 ; in order that the horizontal contribution of the magnetic field of the levitating magnet is not cancelled and varies according to the position of the levitating magnet. 
         [0050]    According to the invention; the sensor  15  is in the centre of a hole of the magnetic to mirror; where no field emitted by the coils  32   33  can reach it. 
         [0051]    According to the invention; the magnetic minor used to optimise the magnetic efficiency of the ring magnet  31  and the coils and cores  32   33 ; has a hole in the centre where the sensor detect the position of the levitated magnet and iron  21   22 . 
         [0052]    Another way to summary this is that the iron or iron silicon plate is a minor for the ring magnet and the coil but not for the sensor and the levitated magnet. According to the invention, the optimised iron plate thickness is around E/10. 
         [0053]    The magnetic field of the coil  32  and  33  avoids the hole and over pass it. 
         [0054]    The consequence of this; are that this combination of magnet electromagnet and iron or iron silicon has exactly the same behaviour as the one described figure one, but.
       Thickness and weight and of
           the ring magnet  31     the coil and core  32     
               are divided by 2   
 
         [0059]    By the same the power requested to setup the levitation is also divided by 2 because for the same current generating the same field inside the half coil; the voltage of the half coil is divided by 2. This means the efficiency of the coils is doubled. 
         [0060]    Then as the consequence; it become possible to use a linear power supply that deliver power up to 10 W despite of switching power supply that become economically more attractive over 10 W. 
         [0061]    In fact a linear power supply using a voltage transformer and diode bridge and capacitor and regulator; can deliver during a short time over power, but average must respect some limit imposed by the size of the transformer. 
         [0062]    Means for average power under 4 W short time peak power 15 W may easily be to reached with no danger with a linear power supply of cost under 1 USD.
   Then the thermal protection must be a combination of short term over power; over 20 W for example, and long term; under 10 W.   Then as a consequence; an average power supply of 4 W may become very cheap to dissipate; in the main electronic board. Over 5 W average power it is necessary to dissipate the electronic over heating in aluminium.   
 
         [0065]    Under 5 W; it becomes possible to dissipate the heat thanks to the iron plate; with no additional cost. By the same the heat of the copper coil and the iron core is also easily dissipated in the iron plate. 
         [0066]    For example, the cost for D=180 mm and 4 coils is 2 Usd for ferrite magnet, 1.5 Usd for copper; 6 Usd for neodymium iron bore magnet, and 1 Usd for linear power supply able to deliver 15 W during a short time; 1.4 USD for electronic board; and 1 USD for iron plate. 
         [0067]    This means almost 13 USD for basic bill of material not including structure and wires and all accessories. 
         [0068]    For a small one axe stabilised D=90 mm; the ring ferrite magnet is 0.2 usd; the 2 copper coils are 0.25 Usd; 0.6 Usd for neodymium iron bore magnets and 1 Usd for linear power supply able to deliver 15 W during a short time; 0.7 USD for electronic board. 0.5 USD for the iron. 
         [0069]    This means around 3.15 USD for the basic bill of material. 
         [0070]    For a small 2 axe stabilised D=90 mm; the ring ferrite magnet is 0.2 Usd; the 2 copper coils are 0.5 Usd; 0.6 Usd for neodymium iron bore magnets and 1 Usd for linear power supply able to deliver 15 W during a short time; 1.4 USD for the electronic board. 0.5 USD for the iron plate. 
         [0071]    This means around 4.2 USD for the basic bill of material. 
       CONCLUSION 
       [0072]    The use of a magnetic mirror made of pure iron or of magnetic alloy like silicon alloy allow a reduction of the cost from
       23.5 USD to 13 USD   for D=180 mm levitator 2 axis stabilised means 45% reduction cost.   6.5 USD to 3.15 USD   for D=90 mm levitator one axis stabilised means 50% reduction cost   7.3 USD to 4.2 USD   for D=90 mm levitator 2 axis stabilised means 42% reduction cost and around 40% reduction of the weight, of the heat; of the power requested, of the magnet thickness       and a dramatic reduction of the whole base thickness.   
 
         [0000]    
       
         
               
               
               
               
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
               
               
               
             
           
               
                   
               
               
                   
                   
                   
                   
                   
                 base 
                 globe 
                 Levitated 
                 set up 
                 set up 
                 for turning 
                 for turning 
               
               
                 D 
                   
                   
                   
                   
                 weight 
                 size 
                 weight 
                 one axe 
                 2 axes 
                 one axe 
                 2 axes 
               
               
                 mm 
                 d 
                 E 
                 E′ 
                 h 
                 g 
                 mm 
                 g 
                 W 
                 W 
                 W 
                 W 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 90 
                 45 
                 15 
                 15 
                 25 
                 400 
                 100 
                 60 
                 6 
                 9 
                 1.5 
                 3 
               
               
                 120 
                 60 
                 15 
                 15 
                 30 
                 800 
                 140 
                 120 
                 9 
                 14 
                 1.5 
                 3 
               
               
                 180 
                 90 
                 20 
                 20 
                 45 
                 1800 
                 200 
                 400 
                 9 
                 14 
                 1.5 
                 3 
               
               
                   
               
             
          
         
       
     
         [0080]    As a consequence of the invention; the base is not affecting any more the environment and may be used near a computer or a television, thanks to the trap of the magnetic field of the base&#39;s magnet. 
         [0081]    The environment is not affecting the behaviour of the base, because the magnetic lines of the magnet and electromagnet are trapped inside iron alloy. 
         [0082]      FIG. 4  describes the most efficient realisation of the invention. 
         [0083]    For a question of clear understanding of the drawing  FIG. 4 ; the ring magnet and the copper coils are not represented. Only the iron parts are represented. 
         [0084]    The iron mirror  41  reflects the ring magnet field and the field are also guided inside the iron cores  43 . By this way almost no field from the magnet cross the mirror  41  level. 
         [0085]    The iron cores  42  and the iron part  45  traps the magnetic field and reduces the air gap to the minimum. By this way; the magnetic field of coil does not cross the mirror level and because of the very short air gap it is increase by a factor 2. 
         [0086]    The horizontal field contribution of the levitating magnet is also trapped into the cores  42  and iron parts  45 ; and because the air gap is reduced this field is also increased around the sensors. 
         [0087]    Then also; the sensors  44  best position is over the part  45 ; at a place where the magnetic field of the coil is cancelled. 
         [0088]    The adjustment of the position of the part  45  allows cancelling completely the magnetic field of the coils on the sensors  44 .