Patent ID: 8517708
Filing Date: 2013-08-27
Classification: F02M,F04D

Abstract:
1. A fuel pump that draws fuel and discharges the drawn fuel after pressurizing the drawn fuel, the fuel pump comprising: a rotatable member that is configured into a generally circular disk form and includes a plurality of blades, which are arranged one after another in a circumferential direction, and a ring portion, which is annular and is placed radially outward of the plurality of blades; and a flow passage member that includes: an enlarged space is formed in a slide surface, which is provided in the inner wall surface of the receiving portion and along which an axial end surface of the ring portion slides upon the rotation of the rotatable member; the enlarged space is placed in a predetermined circumferential range of the slide surface that circumferentially extends from one circumferential point to another circumferential point on the slide surface; the one circumferential point on the slide surface is located radially outward of a front side end part of the suction port along a first imaginary radial line, which radially extends from a rotational axis of the rotatable member through the front side end part of the suction port, and the front side end part of the suction port is located at a front side end of the suction port in the rotational direction of the rotatable member; the another circumferential point on the slide surface is located radially outward of a predetermined location of the pump flow passage along a second imaginary radial line, which radially extends from the rotational axis of the rotatable member through the predetermined location of the pump flow passage, and a fuel pressure at the predetermined location of the pump flow passage is generally equal to a fuel pressure in a corresponding location of a radial gap, which is located radially outward of the predetermined location of the pump flow passage along the second imaginary radial line and is formed between an outer peripheral wall surface of the ring portion and an inner peripheral wall surface of the receiving portion, upon the rotation of the rotatable member; the enlarged space is communicated with the pump flow passage and has an axial gap size, which is axially measured between an axial bottom surface of the enlarged space and the axial end surface of the ring portion and is larger than that of an axial slide gap between the slide surface and the axial end surface of the ring portion; and a radially outer of the flow passage groove, which forms the pump flow passage, is radially outwardly recessed on a downstream side of the suction port to form the enlarged space.