Fuel pump

A fuel pump comprising:

• an outer gear having a plurality of inner teeth;
• an inner gear having a plurality of outer teeth and eccentrically meshing with the outer gear;
• a rotation shaft that is driven to rotate;
• a joint component that connects the rotation shaft to the inner gear to transmit a driving force of the rotation shaft to the inner gear;
• a thrust bearing that supports the rotation shaft in an axial direction;
• and
• a pump housing that defines a cylindrical gear housing chamber housing the outer gear and the inner gear from both sides in the axial direction such that the outer and inner gears are rotatable, wherein the pump housing has a pair of sliding surface parts against which the outer gear and the inner gear slide,
• wherein the outer gear and the inner gear rotate, while expanding and contracting volumes of a plurality of pump chambers formed between the outer gear and the inner gear, to sequentially draw fuel into each of the pump chambers through an intake passage and discharge through a discharge passage, and
• the pump housing has an annular groove formed in an annular shape opposing the outer gear and recessed in the axial direction from at least one of the pair of sliding surface parts to make an area on a radially outer side of the intake passage and an area on a radially outer side of the discharge passage communicate with each other, wherein
• the annular shape of the annular groove is formed uninterruptedly,
• the joint component rotates the outer gear and the inner gear;
• the joint component is in contact with the thrust bearing;
• the joint component has:
• a main body fitted with the rotation shaft in a joint housing chamber, and
• an insertion part having a plurality of extended members respectively arranged at a plurality of locations positioned circumferentially around the rotation shaft, each of the plurality of extended members extending from the main body in the axial direction and being respectively inserted in insertion holes of the inner gear defined at a plurality of positions through a clearance;
• and
• the insertion holes pass through the inner gear in the axial direction and the insertion part of the joint component extends in the insertion holes in the axial direction.