Electromagnetic fuel pump

Abstract

The invention can secure an improved pump operation while minimizing a loss of a magnetomotive force generated by an electromagnetic coil and making it possible to achieve a compact structure and a weight saving of an apparatus, in a plunger type electromagnetic fuel pump. In an electromagnetic fuel pump ( 1 ) which pressure-feeds a fuel by controlling a current application to an electromagnetic coil ( 5 ) and repeating generation and elimination of a magnetic force so as to slidably reciprocate a plunger ( 3 ) arranged in a cylinder ( 4 ) and having a proximal end side urged by a return spring ( 41 ), an insertion hole ( 35 ) for inserting the return spring ( 41 ) is provided from the proximal end surface of the plunger ( 3 ) at a predetermined depth along the center axis of the plunger ( 3 ), and the inner peripheral surface of the insertion hole ( 3 ) is formed as a spring guide retaining the outer peripheral leading end side of the return spring ( 41 ).

1 . An electromagnetic fuel pump comprising:
 a cylinder having a discharge port provided with a check valve on a leading end side and an intake port on a proximal end side thereof;   a plunger slidably fitted in the cylinder, the plunger having a fuel passage formed along an axis thereof and provided with a check valve therein;   a return spring arranged on the proximal end side between the plunger and the cylinder for urging the plunder in a leading end side direction; and   an electromagnetic coil arranged on the outside of the cylinder, a current application to the electromagnetic coil being controlled so as to repeat generation and elimination of a magnetic force to cause the plunger to slidably reciprocate for delivering a fuel under pressure;   wherein an insertion hole for inserting the return spring is provided in a proximal end surface of the plunger at a predetermined depth along a center axis of the plunger, and an inner peripheral surface of the insertion hole is formed as a spring guide retaining an outer peripheral leading end side of the return spring.   
   
   
       2 . The electromagnetic fuel pump as claimed in  claim 1 , wherein a second insertion hole for inserting the return spring is provided in a proximal end surface of the cylinder at a predetermined depth along the center axis of the cylinder, and an inner peripheral surface of the second insertion hole is formed as a spring guide retaining an outer peripheral proximal end side of the return spring.