Nippondenso Co., Ltd.

Minoru Yasuda

Motoya Ito

Takahiko Kato

Takeshi Matsuda

Atsushige Kobayashi

A liquid pump has a DC motor and a pump in a cylindrical casing. A pair of brushes are slidably contacted with a commutator of an armature while being biased by springs. The specific resistance of the positive brush is lower than the specific resistance of the negative brush to enable the voltage drop at the brushes to be decreased and motor efficiency to be increased without increasing commutator wearing speed. The biasing force provided by the spring biasing the positive brush is lower than the biasing force provided by the spring biasing the negative brush.

DC motor with improved brushes and liquid pump using the same

In order to reduce noise generated in a westco pump when fluid hits a finishing end of a pump channel, finishing ends of grooves formed in a side wall of a casing body and a casing cover to form a pump channel are shifted by an amount equal to 1/2 of the pitch of blade elements in relation to the rotating direction of an impeller. As a result, the timings the fluid under high pressure hits the finishing ends of the grooves are staggered, thus decreasing the collision sound.

Westco pump and noise suppression structure

A regenerative pump includes a casing which a recessed fluid flow passage interconnecting a suction port and a discharge port is formed in an arcuate shape. An impeller is provided rotatably with respect to the casing and formed with a plurality of vane members which face the recessed fluid flow passage. A recessed damping portion is formed in a terminal end portion of the recessed fluid flow passage on a discharge port side thereof to begin at a position corresponding to the discharge port and extend along a rotating direction of the impeller. The recessed damping portion has a depth which is smaller than that of a main depth of the recessed fluid flow passage and substantially constant.

Regenerative pump and casing thereof

There is disclosed a trochoid pump in which a friction between a rotor and its support portion is reduced, thereby reducing a drive torque and wear of these parts. An inner rotor of the trochoid-type fuel pump is rotatably supported by a bushing through a bearing. An outer rotor is rotatably received in an inner periphery of a spacer. A first groove is formed in a portion of the outer periphery of the bushing disposed close to a discharge port, and a discharge fuel is introduced into this groove. A second groove is formed in a portion of the inner periphery of the spacer disposed close to the discharge port, and the discharge fuel is introduced into this groove. Although the inner rotor is urged toward the bushing by the fuel pressure of the discharge port, the urging force to urge the inner rotor toward the bushing is weakened by the discharge fuel introduced into the first groove, thereby reducing a friction. Although the outer rotor is urged against the spacer, the urging force to urge the outer rotor against the spacer is weakened by the discharge fuel introduced into the second groove, thereby reducing a friction.

Gear-type pump having pressure balanced support

A pump comprises an outer rotor and an inner rotor. A plurality of pressure chambers are defined between the outer rotor and the inner rotor to cause fluid to be sucked from a suction port and discharged to a discharge port by the movement of these pressure chambers with changing their volumes. A pressure relief passage is opened between the discharge port and the suction port and communicated directly with a fuel tank provided outside the pump. This causes the pressure in the pressure chamber to be reduced before the pressure chamber is communicated with the suction port. In consequence, it is possible to prevent the fuel of discharge pressure in the pressure chamber from being brought in the suction port, thereby preventing the generation of vapor caused due to vacuum boiling and the reduction of discharge rate.

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Chiryu, Japan

Minoru Yasuda