Axially compact small fan

Abstract

A flat portable fan with an impeller on a motor shaft and a commutatorless direct current motor is provided having a printed circuit board in the stator and an axially magnetized permanent magnet in the rotor. The circuit board comprises a printed circuit having electronic components of the fan drive and is made from an iron base material with an insulating layer, which carries the stator windings and an axial starting bearing for the rotor. The impeller is mounted in a cylindrical rotor mounting support and is driven by the axially magnetized permanent magnet. The iron base material and the permanent magnet substantially define a planar air gap.

We claim:  
     
       1. Flat portable fan with an impeller on a motor shaft and a commutatorless direct current motor including a stator, a rotor, and a fan drive having electronic control components, said motor having a printed circuit board in the stator and having an axially magnetized permanent magnet in the rotor, the circuit board being made of an iron base material with an insulating layer thereon and comprising a printed circuit having conductors which contact the electronic components of the fan drive, made from an iron base material with an insulating layer,  the circuit board carrying stator windings and an axial starting bearing for the rotor, the impeller being mounted in a cylindrical rotor mounting support and being driven by the axially magnetized permanent magnet, and the iron base material and the permanent magnet substantially defining a planar air gap. 
     
     
       2. Flat portable fan comprising: 
       a commutatorless direct current drive motor having a motor shaft, a stator, and electronic control components;  
       an air impeller rotor structure mounted directly on the motor shaft, the structure providing the dual function of both the rotor of the motor and the impeller of the fan;  
       an axially magnetized permanent magnet mounted internally of the impeller rotor structure, the impeller rotor being mounted in a cylindrical rotor mounting support and being driven by interaction between the stator and the axially magnetized permanent magnet;  
       a printed circuit board mounted on the stator, the printed circuit board being constructed of iron as a base material with an insulating layer thereon, the iron base material providing the dual function of both a component of strength for a mounting base and a magnetic yoke for the motor;  
       a printed circuit on the insulating layer of the circuit board having thereon the electronic control components of the motor;  
       stator windings mounted on the insulating layer of the circuit board;  
       an axial starting bearing for the rotor carried by the printed circuit board; and  
       the iron base material and the permanent magnet defining substantially a planar air gap.  
     
     
       3. Portable fan according to claim  1  or  2 , wherein the stator windings are formed by an oval coil, the motor shaft is located approximately in the center of the coil, and further comprising magnetically acting means provided for a specific starting position of the rotor. 
     
     
       4. Portable fan according to claim  1  or  2 , wherein the starting bearing for the rotor is formed by a plastic bearing supporting the motor shaft with a track cap. 
     
     
       5. Portable fan according to claim  4 , wherein openings are provided in the circuit board, and motor casing parts are provided with projections which can snap into the openings in the circuit board. 
     
     
       6. Portable fan according to claim  4 , wherein openings are provided in the circuit board, and motor bearing parts are provided with projections which can snap into the openings provided in the circuit board. 
     
     
       7. Portable fan according to claim  1  or  2 , wherein the rotor mounting support has a bearing tube and a support member for the bearing tube. 
     
     
       8. Portable fan according to claim  7 , wherein the bearing tube is formed by a sintered part and is inserted in non-rotary manner in an opening of the printed circuit board and is additionally retained and centered by the supporting member constructed as a plastic moulding. 
     
     
       9. Portable fan according to claim  8 , wherein the supporting member for the bearing tube at the same time centers and orients the coil. 
     
     
       10. Portable fan according to claim  7 , wherein openings are provided in the circuit board, and motor casing parts are provided with projections which can snap into the openings in the circuit board. 
     
     
       11. Portable fan according to claim  5 , wherein openings are provided in the circuit board, and motor bearing parts are provided with projections which can snap into the openings provided in the circuit board. 
     
     
       12. Portable fan according to claim  5 , wherein the bearing tube is formed by a plastic moulding and is inserted in non-rotary manner in an opening of the printed circuit board and is additionally retained and centered by the supporting member also constructed as a plastic moulding. 
     
     
       13. Portable fan according to claim  1  or  2 , wherein openings are provided in the circuit board and motor casing parts are provided with projections which can snap into the openings in the circuit board. 
     
     
       14. Portable fan according to claim  1  or  2 , wherein the electronic components are combined in an integrated circuit. 
     
     
       15. Portable fan according to claim  1  or  2 , wherein the coil comprises a bifilar winding. 
     
     
       16. Portable fan according to claim  1  or  2 , wherein axially the overall height of the portable fan is less than 30 mm. 
     
     
       17. Portable fan according to claim  1  or  2 , wherein the impeller can start in both rotation directions and has radially oriented blades, the air being sucked in axially and blown out radially. 
     
     
       18. Portable fan according to claim  1  or  2 , wherein thefurther comprising a casing having an outer circumference of the casingwhich is profiled by depressions for fastening therein thean apparatus to be ventilated. 
     
     
       19. Portable fan according to claim  1  or  2 , wherein openings are provided in the circuit board, and motor bearing parts are provided with projections which can snap into the openings provided in the circuit board.