Fuel pump, fuel supply equipment using fuel pump and method for manufacturing fuel pump

Abstract

A fuel pump mounted in the fuel tank for the motor cycle comprises a motor and a pump driven by the motor for increasing a pressure of the sucked fuel. The motor is a brushless motor and has a stator core, coils and a rotor. An electrical energization for the coils wound around the stator core is controlled in response to a rotating position of the rotor, thereby the rotor is rotated. The rotor has a shaft, a rotating core and a permanent magnet, and the rotor is rotatably mounted at the inner circumference of the stator core. The permanent magnet is mounted at the outer circumference of the rotating core and magnetically energized so as to form magnetic poles different alternatively in a rotating direction at the outer circumferential surface facing the stator core.

Description

CROSS-REFERENCE TO RELATED APPLICATION [0001] This application is based on Japanese Patent Applications No. 2004-110164 filed on Apr. 2, 2004, No. 2004-266739 filed on Sep. 14, 2004, No. 2004-327367 filed on Nov. 11, 2004, and No. 2004-355575 filed on Dec. 8, 2004, the disclosure of which is incorporated herein by reference. FIELD OF THE INVENTION [0002] This invention relates to an in-tank type fuel pump for a motorcycle, fuel supply equipment using the fuel pump and a method for manufacturing the fuel pump. BACKGROUND OF THE INVENTION [0003] In general, it has been well known in the art to provide a motor in which a current fed to a rotor having a coil wound around it is controlled by a commutator and the rotor is rotated. Then, as a driving source for a fuel pump for absorbing the fuel in the fuel tank and feeding the fuel to an engine acting as a fuel consumption device, there has been used the motor controlled by the commutator as described above (refer to Patent Document 1, fo...

AI Technical Summary

Benefits of technology

[0023] The inventions described in claims are operated such that some magnetic poles formed in a circumferential direction of a stator core are changed over under controlling of an electrical energization for the coils wound around the stator core, the rotating members at the pump is rotated together with the rotor through the changing-over of the magnetic poles and a pressure of the fuel is increased. That is, the fuel pump using the brushless motor is installed in the fuel tank of the motorcycle. Both sliding resistance and fluid resistance can be reduced as compared with those of the commutator controlled motor because no commutator is used in the brushless motor. With such an arrangement as above, a motor size can be reduced and its low current can be attained under the same output because the aforesaid motor efficiency is improved with the result that the fuel pump efficiency is improved. Accordingly, it is possible to mount the fuel pump within the fuel tank of the motorcycle having a smaller size as compared with that of a four-wheeled vehicle.

Problems solved by technology

However, the motor controlled by the commutator has some disadvantages that a motor efficiency is decreased with the result that an efficiency of the motor is decreased because a sliding resistance between the commutator and a brush and a fluid resistance received at the grooves formed for dividing the commutator into each of the segments are generated.

In addition, the motor controlled by the commutator shows a problem that a motor lifetime becomes short due to a wearing at the sliding locations between the commutator and the brush.

As described above, when a height of the fuel pump installed in the fuel tank is increased, there occurs a problem that a structure for installing the fuel pump in the fuel tank becomes complex.

When it is tried to utilize the fuel pump having a commutator controlled motor of a four-wheeled vehicle as a driving source for a motorcycle where a battery capacity that can be mounted on the motorcycle is low due to a narrow installing space, an assurance of electrical power supplied to the fuel pump sometimes becomes difficult because an efficiency of the fuel pump is low.

In addition, when the fuel tank is small in size for the motorcycle, it is difficult to mount the fuel pump in the fuel tank.

Additionally, deteriorated fuel or low quality fuel containing alcohol, for example, may be used in a motorcycle and when the fuel pump having a commutator controlled motor is mounted on the motorcycle utilizing such a deteriorated fuel or low quality fuel as above, electric corrosion or corrosion may occur at the sliding contact portion between the commutator and the brush and an inferior electrical conduction state may occur.

There occurs a problem in the brushmotor that a motor efficiency is reduced with the result that a fuel pump efficiency is reduced by a sliding resistance between the commutator and the brush as well as a fluid resistance received at the grooves arranged for dividing the commutator into each of the segments.

In addition, the brushmotor has a problem that the motor life becomes short due to a wearing of the sliding portion between the commutator and the brush.

Additionally, when deteriorated fuel or low quality fuel is used as fuel, application of the brushmotor to the fuel pump causes the sliding portion between the commutator and the brush to generate an electrical corrosion or poor electrical contact and there occurs a possibility that an electrical non-conductive state is produced.

In addition, when the coil of the rotor in the aforesaid brushmotor is formed in a distributed winding type where the coil is wound over a plurality of teeth, the windings at the coil ends are crossed to each other and it becomes difficult to increase a rate of occupancy of the winding per magnetic pole.

However, it is hard to seal between the bearing slidingly contacted with the rotary shaft and the pump chamber, and the Patent Document 2 does not disclose a structure for sealing between the pump chamber and the bearing.

In addition, even if the pump chamber and the bearing can be sealed to each other, there remains a problem that a sliding resistance is increased and the sliding friction is increased because the sliding part between the rotary shaft and the bearing is not lubricated with fuel.

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