Abstract: A fuel pump improved in pump efficiency is provided. An impeller rotating in a pump casing has an approximately disk-shaped configuration with a group of recesses formed in a region extending along the outer peripheries of the obverse and reverse sides of the impeller. The recesses are repeatedly arranged in the circumferential direction at a distance between each pair of adjacent recesses. The radially outer end face of each recess slantingly extends radially outward from a middle plane in the direction of thickness toward the obverse and reverse sides. With this fuel pump, the incidence of separation or vortex formation in the flow of fuel is minimized, and a high pump efficiency can be obtained.

Abstract: A fuel pump capable of using the pump efficiency most efficiently without reducing the useful service life is provided. A relatively large clearance allowing for the expected amount of wear is ensured in a region where the flow passage groove pressure is low. In a region where the flow passage groove pressure is high, it is unnecessary to allow for the wear. Therefore, the clearance is set relatively small.

Abstract: A fuel pump in which a terminal plate can be liquid-tightly mounted to a body upper and prevented from being dislodged from the body upper without the need of other component parts is provided. The terminal plate is formed with a cut and raised portion for preventing dislodging. When the terminal plate is inserted into a terminal plate through-hole having a step portion, a projection and a press-fit portion, the cut and raised portion is closed by being pressed with the projection and allowed to reach the step portion without contacting the press-fit portion. Then, the cut and raised portion returns to its natural configuration. Thus, the terminal plate is prevented from being dislodged to fall into the fuel pump. Because the press-fit portion is not damaged when the terminal plate is inserted, the terminal plate can be placed in liquid-tight contact with the body upper block.

Abstract: A fuel pump improved in pump efficiency is provided. An impeller rotating in a pump casing has an approximately disk-shaped configuration with a group of recesses formed in a region extending along the outer peripheries of the obverse and reverse sides of the impeller. The recesses are repeatedly arranged in the circumferential direction at a distance between each pair of adjacent recesses. The radially outer end face of each recess slantingly extends radially outward from a middle plane in the direction of thickness toward the obverse and reverse sides. With this fuel pump, the incidence of separation or vortex formation in the flow of fuel is minimized, and a high pump efficiency can be obtained.

Abstract: A fuel pump capable of using the pump efficiency most efficiently without reducing the useful service life is provided. A relatively large clearance allowing for the expected amount of wear is ensured in a region where the flow passage groove pressure is low. In a region where the flow passage groove pressure is high, it is unnecessary to allow for the wear. Therefore, the clearance is set relatively small.

Abstract: A fuel pump improved in pump efficiency is provided. An impeller rotating in a pump casing has an approximately disk-shaped configuration with a group of recesses formed in a region extending along the outer peripheries of the obverse and reverse sides of the impeller. The recesses are repeatedly arranged at a distance between each other in the circumferential direction with a partition provided between each pair of adjacent recesses. The radially inner and outer end portions of the partition are positioned on the same radius, and the radially middle portion of the partition is curved rearward in the direction of rotation of the impeller. With this fuel pump, the incidence of separation or vortex formation in the flow of fuel is minimized, and a high pump efficiency can be obtained. It is preferable that the maximum amount of curvature of the partition should be from 0.1 to 1.

Abstract: A fuel pump in which a terminal plate can be liquid-tightly mounted to a body upper and prevented from being dislodged from the body upper without the need of other component parts is provided. The terminal plate is formed with a cut and raised portion for preventing dislodging. When the terminal plate is inserted into a terminal plate through-hole having a step portion, a projection and a press-fit portion, the cut and raised portion is closed by being pressed with the projection and allowed to reach the step portion without contacting the press-fit portion. Then, the cut and raised portion returns to its natural configuration. Thus, the terminal plate is prevented from being dislodged to fall into the fuel pump. Because the press-fit portion is not damaged when the terminal plate is inserted, the terminal plate can be placed in liquid-tight contact with the body upper block.

Abstract: A jet opening 13a for injecting fuel can be opened and closed by a ball valve 23 of a movable element 20. An orifice plate 14 is disposed on a downstream side of the jet opening and has between about eight to eighteen circular jet holes formed for further atomizing fuel particles exhausted by the jet opening 13a. Upstream side openings of the jet holes can be dispersed on a plurality of circles. A thickness t of the orifice plate and a diameter &phgr;d of the jet holes can be set to be 0.53≦t/&phgr;d≦0.82. A shortest distance L between said upstream side openings of the jet holes and a diameter &phgr;d of the jet holes can be set to be L>&phgr;d.

Abstract: A fuel injector (20) may have an approximately cylindrical body (30) and a valve (40) adapted to reciprocate within a body (30). A valve seat (50) may have an opening (56) and may be positioned downstream of valve (40) such that opening (56) becomes closed when valve (40) moves downstream and opening (56) becomes open when valve (40) moves upstream. An orifice plate (60) may be coupled to the downstream side of valve seat (50). Valve seat (50) may press fit into the interior of body (30) and at least a portion of the outer surface of valve seat (50) preferably frictionally contacts the interior surface of body (30). One or more protrusions (32) may be formed on the interior surface of body (30). At least one protrusion (32) may optionally contact orifice plate (60). Further, the portion of the outer surface of valve seat (50) that is closest to valve seat opening (56) preferably does not frictionally contact the interior surface of body (30).