Abstract: A drive controller that controls a drive of a motor. The drive controller performs a collision force moderation control during a motor start time, during which a collision force in a collision between a shaft outwall with an impeller hole inwall for a positioning is moderated, by changing a power supply at a stage transition time of transiting from a position detection to a position determination. The maximum value of a first output value during a position detection time is set to be greater than a first threshold that at least causes a rotation number of the motor to yield a detectable induction voltage. A second output value during a position determination time is set to be lower than a second threshold that causes a wear or a breakage of an impeller by the collision force.

Abstract: A microcomputer operates as a positioning part positions a rotor at a control start position, which is a position of the rotor relative to a stator to be able to start controlling driving of a brushless motor, by supplying a current to a winding set a number of times “n” (n is an integer equal to two or more) before starting to control driving of the brushless motor. The microcomputer, operating as the positioning part, controls electric power supplied to the winding set so that the rotor rotates in the same direction at each of “n” times of power supply to the winding set, that is, at each of “n?1” times of switchovers of power supply to the winding set.

Abstract: A fuel pump includes a cylindrical stator having a plurality of windings, a rotor rotatably disposed radially inward of the stator, a shaft integrally rotatable with the rotor, an impeller including a fitting hole to which an end portion of the shaft is fitted, and a balance weight disposed in the impeller. The balance weight is formed so as to be symmetrical about a point of symmetry lying on an axial center of the impeller.

Abstract: A fuel pump includes a shaft integrally rotatable with a rotor, and an impeller including a fitting hole to which the shaft is fitted. The shaft includes shaft contact surfaces which contact flat surfaces that form the fitting hole when the shaft rotates. The shaft contact surfaces include grooves formed to extend in a center axis direction of the shaft.

Abstract: A microcomputer of a drive control device for controlling the driving of a brushless motor has a positioning part and a torque acceleration control unit. The positioning unit controls the power to be supplied to the windings, to thereby position the rotor at a drive start position which is a position of the rotor relative to the stator at which the drive control of the brushless motor can start, before starting the drive control of the brushless motor. The torque acceleration control unit controls the power to be supplied to the windings so that a torque acceleration falls within a predetermined range that the collision stress generated when the outer wall of the end of the shaft collides with the inner wall of the hole of an impeller (rotating member) is equal to or smaller than a predetermined value, when the rotor is positioned.

Abstract: An engaging hole-of an impeller, which receives a shaft, is formed by an impeller first planar surface, which is contactable with a shaft first planar surface, an impeller second planar surface, which is contactable with a shaft second planar surface, and an impeller first curves surface-and an impeller second curved surface, which connect between the shaft first planar surface-and the shaft second planar surface. A first groove and a second groove, which are communicated with the engaging hole, are formed in the impeller first curved surface and the impeller second curved surface, respectively. When the shaft first planar surface contacts the impeller first planar surface upon rotation of the shaft in one direction, the first groove is deformed by an applied force. Thereby, the shaft second planar surface and the impeller second planar surface contact with each other.

Abstract: An ECU of a fuel pump executes a feedback control to drive a motor part and sets a rotation speed of an impeller to become a rotation speed corresponding to the target fuel pressure. The ECU detects whether a vapor is generated in a fuel of a pump chamber of the fuel pump, based on a fuel pressure detected by a pressure sensor. When a generation of the vapor is detected, the ECU sets a rotation speed of the impeller to be higher than the rotation speed under a normal control for a predetermined time with a result that the vapor in the pump chamber and a fuel flow channel is discharged into a vapor discharge hole. Thus, the vapor of the pump chamber is discharged from the vapor discharge hole to an outside of the fuel pump.

Abstract: A permanent magnet of a rotor core of a rotor includes a first recess and a second recess, which are formed in an outer wall to correct a dynamic balance of the rotor. The permanent magnet is a bonded magnet that is formed by molding a mixture material, which is a mixture of resin and magnetic powder. The first recess and the second recess are formed at the time of molding the permanent magnet. Furthermore, the first recess and the second recess are formed at two axial ends, respectively, of the permanent magnet.

Abstract: A drive controller that controls a drive of a motor. The drive controller performs a collision force moderation control during a motor start time, during which a collision force in a collision between a shaft outwall with an impeller hole inwall for a positioning is moderated, by changing a power supply at a stage transition time of transiting from a position detection to a position determination. The maximum value of a first output value during a position detection time is set to be greater than a first threshold that at least causes a rotation number of the motor to yield a detectable induction voltage. A second output value during a position determination time is set to be lower than a second threshold that causes a wear or a breakage of an impeller by the collision force.

Abstract: A microcomputer operates as a positioning part positions a rotor at a control start position, which is a position of the rotor relative to a stator to be able to start controlling driving of a brushless motor, by supplying a current to a winding set a number of times “n” (n is an integer equal to two or more) before starting to control driving of the brushless motor. The microcomputer, operating as the positioning part, controls electric power supplied to the winding set so that the rotor rotates in the same direction at each of “n” times of power supply to the winding set, that is, at each of “n?1” times of switchovers of power supply to the winding set.

Abstract: A rotor of a brushless motor used in a fuel pump includes a permanent magnet having first and second ends that are configured to have a thickness ratio so that a degree of margin of those ends, which is a difference between an allowable stress and a temperature stress due to expansion and contraction of a rotor core caused by a temperature change is equal to or greater than a preset value. As a result, a cracking of the permanent magnet on the both ends that is caused by repeated expansions and contractions of the rotor core is prevented.