Electric gear pump

Abstract

An electric gear pump comprising a gerotor that may rotate about an axis of rotation A, comprising an external spur rotor and an internal spur rotor arranged outside the external spur rotor; a stator having electrical windings arranged outside the internal spur rotor; at least one magnet at least partially housed in the internal spur rotor in such a way as to cause the gerotor to rotate when the electrical windings of the stator are supplied with current; in which the internal spur rotor comprises a cylindrical external surface centred on the axis of rotation A; the magnet comprises an external surface separated from the external surface of the internal spur rotor; the external surface of the magnet is shaped in such a way as to define a constant radial distance d between the magnet and the corresponding portion of the external surface of the internal spur rotor.

1 . An electric gear pump ( 4 ) comprising:
 a gerotor ( 9 ) configured to rotate about an axis of rotation (A), the gerotor comprising an external spur rotor ( 21 ) and an internal spur rotor ( 22 ) arranged outside the external spur rotor ( 21 );   a stator ( 25 ) having electrical windings ( 26 ) arranged outside the internal spur rotor ( 22 );   at least one magnet ( 23 ) at least partially housed in the internal spur rotor ( 22 ) in such a way as to cause the gerotor ( 9 ) to rotate when the electrical windings ( 26 ) of the stator ( 25 ) are supplied with current;   wherein:   the internal spur rotor ( 22 ) comprises a cylindrical external surface ( 29 ) centered on the axis of rotation (A);   the magnet ( 23 ) comprises an external surface ( 30 ) separated from the external surface of the internal spur rotor ( 22 ); and   the external surface ( 30 ) of the magnet ( 23 ) is shaped in such a way as to define a constant radial distance (d) between the magnet ( 23 ) and the corresponding portion of the external surface ( 29 ) of the internal spur rotor ( 22 ).   
     
     
         2 . A pump as claimed in  claim 1 , wherein the pump ( 4 ) comprises a support base ( 24 ) for the gerotor ( 9 ) and a closure cover ( 27 ); wherein the internal spur rotor ( 22 ) comprises a lower surface ( 31 ) for coupling with the base ( 24 ) and an upper surface ( 32 ) for coupling with the cover ( 27 ), and wherein the internal spur rotor ( 22 ) comprises at least one seat ( 33 ) for housing the magnet ( 23 ) on the lower surface ( 31 ) or on the upper surface ( 32 ). 
     
     
         3 . The pump as claimed in  claim 2 , wherein the seat ( 33 ) is a channel with a shape corresponding to the magnet ( 23 ). 
     
     
         4 . The pump as claimed in  claim 2 , wherein, when inserted in the seat ( 33 ), the magnet ( 23 ) is flush with the lower surface ( 31 ) or the upper surface ( 32 ) of the internal spur rotor ( 22 ). 
     
     
         5 . The pump as claimed in  claim 4 , wherein the pump comprises at least two magnets ( 23 ) and the internal spur rotor ( 22 ) comprises at least one lower seat ( 33 ) on the lower surface ( 31 ) and at least one upper seat ( 33 ) on the upper surface ( 32 ). 
     
     
         6 . The pump as claimed in  claim 5 , wherein the lower and upper seats ( 33 ) are aligned along an axis parallel to the axis of rotation A. 
     
     
         7 . The pump as claimed in  claim 5 , wherein a distance between the lower and upper seats ( 33 ) is less than a thickness of the magnet ( 23 ) measured along an axis parallel to the axis of rotation A. 
     
     
         8 . The pump as claimed in  claim 1 , wherein the magnet ( 23 ) is in the form of a ring. 
     
     
         9 . The pump as claimed in  claim 8 , in which wherein the magnet ( 23 ) in the form of a ring is made as a single piece. 
     
     
         10 . A pump assembly for supplying fuel from a tank ( 2 ) to an internal combustion engine ( 3 ); the pump assembly ( 1 ) comprising, in series, a low-pressure electric gear pump ( 4 ) and a high-pressure pump ( 5 ); wherein the low-pressure electric gear pump ( 4 ) is configured according to  claim 1 . 
     
     
         11 . The pump as claimed in  claim 8 , wherein the magnet ( 23 ) in the form of a ring is made as a plurality of adjacent parts.