Electromagnetic pump

Abstract

The present invention provides an electromagnetic pump capable of highly precisely detecting operating positions of a moving member without enlarging the pump. An air-core detecting coil ( 53 ) for detecting reciprocating motion of the moving member ( 10 ) is fitted around a cylinder so as to be coaxial with electromagnetic coils ( 50 a, 50 b ).

1 . An electromagnetic pump comprising: a cylinder; a moving member being movably accommodated in said cylinder, said moving member having a permanent magnet; an air-core electromagnetic coil being fitted around said cylinder, said electromagnetic coil reciprocally moving said moving member in the axial direction when electricity is supplied to said coil; and pump chambers for sending a fluid, said pump chambers being formed in said cylinder, characterized in, 
 that an air-core detecting coil for detecting reciprocating motion of said moving member is fitted around said cylinder so as to be coaxial with said electromagnetic coils.    
   
   
       2 . The electromagnetic pump according to  claim 1 , wherein a plurality of said electromagnetic coils are fitted around the periphery of said cylinder, and said detecting coils are respectively provided close to axial end faces of said electromagnetic coils.  
   
   
       3 . The electromagnetic pump according to  claim 1 , wherein yokes made of a magnetic material are provided to axial end faces of said detecting coil or the axial end faces and an outer circumferential face thereof.  
   
   
       4 . The electromagnetic pump according to  claim 1 , wherein frequency of induced voltage of said detecting coil is twice as high as frequency of the reciprocating motion of said moving member.  
   
   
       5 . The electromagnetic pump according to  claim 1 , wherein flow volume of said pump is detected on the basis of the induced voltage detected by said detecting coil.  
   
   
       6 . The electromagnetic pump according to  claim 1 , wherein flow volume of said pump greater than a prescribed value or not is detected on the basis of a threshold value of the induced voltage detected by said detecting coil.  
   
   
       7 . The electromagnetic pump according to  claim 1 , wherein a normal or abnormal reciprocating motion of said moving member is detected on the basis of a threshold value of the induced voltage detected by said detecting coil.  
   
   
       8 . The electromagnetic pump according to  claim 1 , wherein motion of said moving member is controlled on the basis of a threshold value of the induced voltage detected by said detecting coil.  
   
   
       9 . The electromagnetic pump according to  claim 1 , wherein the induced voltage detected of said detecting coil is detected in a detection range, in which variation of the induced voltage caused by magnetization of said electromagnetic coil is small.