Electrical generator or motor structure – Dynamoelectric – Rotary
Reexamination Certificate
2001-04-20
2003-12-02
Lam, Thanh (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Rotary
C310S052000, C310S064000, C310S260000, C310S045000
Reexamination Certificate
active
06657331
ABSTRACT:
This application is based on Application No. 2000-316515, filed in Japan on Oct. 17, 2000, the contents of which are hereby incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an automotive alternator in which a heat-generating portion is cooled by a liquid coolant.
2. Description of the Related Art
Heat-generating parts such as a rotor winding, a stator winding, a rectifier, and a voltage regulator are mounted in automotive alternators, and to achieve high performance, it is important to suppress temperature increases in the stator winding by efficiently dissipating heat generated, particularly in the stator winding, which is the largest heat-generating part.
It has been proposed conventionally, in Japanese Patent Examined Publication No. HEI 5-16261, for example, that temperature increases in a stator winding in an automotive alternator be suppressed by constructing a distribution channel for a liquid coolant such as water, etc., inside a bracket, filling an electrically-insulating filler composed of a synthetic resin, etc., between a coil end group of the stator winding and the bracket, transferring heat generated in the stator winding to the bracket by means of the electrically-insulating filler, and allowing the heat to be absorbed by the liquid coolant flowing through the distribution channel inside the bracket.
It has also been proposed in Japanese Patent No. 2842500, for example, that temperature increases in a stator winding be suppressed by embedding a tube inside a bracket, the tube constituting a distribution channel for a liquid coolant such as water, etc., extending a portion of the tube out from the bracket, placing the tube in close contact with a coil end group of the stator winding, and allowing heat generated in the stator winding to be absorbed by the liquid coolant flowing through the inside of the tube.
Now the construction of a conventional stator will be explained with reference to FIG.
23
.
As shown in
FIG. 23
, a stator
100
is constituted by a cylindrical stator core
101
composed of a laminated core formed with slots
101
a
extending axially at a predetermined pitch in a circumferential direction, and a stator winding
102
installed in the stator core
101
.
The stator winding
102
is composed of three stator winding phase portions. Each of the stator winding phase portions is manufactured into a generally cylindrical winding assembly by winding one strand of slender copper wire a predetermined number of times into a wave winding at a pitch of three slots, the slender copper wire having a circular cross section coated with electrical insulation. These three winding assemblies are offset from each other at a pitch of one slot in a circumferential direction, and are stacked radially in three layers. Then, the stator
100
is manufactured by reducing the diameter of the three winding assemblies, inserting the three winding assemblies into the stator core
101
, and then pressing the three winding assemblies into the slots
101
a
from a slot opening side.
In the conventional stator
100
manufactured in this manner, because the winding assemblies constituting the stator winding
102
are reduced in diameter and inserted into the stator core
101
, and in addition are pressed into the slots
101
a
from the slot opening side, coil ends composed of bundles of the slender copper wires led out from first slots
110
a
and led into second slots
110
a
three slots away are deformed, and in addition the coil ends overlap radially at outlet portions where the coil ends are led out of the slots
110
a
(or inlet portions where the coil ends are led into the slots). As a result, outer circumferential surfaces of coil end groups of the stator winding
102
have large irregularities in a circumferential direction. Because the positions of the slender copper wires in the coil ends are not specified, large irregularities occur on surfaces of the coil ends. In addition, because the coil ends are formed into bundles of slender copper wires, the slender copper wires are not in close contact with each other in the coil ends, making thermal conductivity in the coil ends poor.
When the cooling construction proposed in Japanese Patent Examined Publication No. HEI 5-16261 is adopted in an automotive alternator mounted with the stator
100
constructed in this manner, the outer circumferential surfaces of the coil end groups and the electrically-insulating filler are in partial contact. Because the outer circumferential surfaces of the coil end groups have irregularities in a circumferential direction, and in addition, the surfaces of the coil ends have irregularities, heat generated in the stator winding
102
is mainly transferred to the electrically-insulating filler via two heat transfer pathways which are directly from the slender copper wires in the coil ends and by means of air in gaps between the slender copper wires and the electrically-insulating filler, and is additionally transferred to the bracket and absorbed by the liquid coolant, cooling the stator
100
.
When the cooling construction proposed in Japanese Patent No. 2842500 is adopted in an automotive alternator mounted with this stator
100
, the outer circumferential surfaces of the coil end groups and the tube are in partial contact. Because the outer circumferential surfaces of the coil end group have irregularities in a circumferential direction, and in addition the surfaces of the coil ends have irregularities, heat generated in the stator winding
102
is mainly transferred to the tube via two heat transfer pathways which are directly from the slender copper wires in the coil ends and by means of air in gaps between the slender copper wires and the tube, and is absorbed by the liquid coolant, cooling the stator
100
.
In conventional automotive alternators, because the outer circumferential surfaces of the coil end groups of the stator winding
102
have large irregularities, and in addition the surfaces of the coil ends have large irregularities, one problem has been that thermal contact between the slender copper wires which constitute the coil end groups and the electrically-insulating filler or the tube is insufficient when the cooling constructions proposed in Japanese Patent Examined Publication No. HEI 5-16261 or Japanese Patent No. 2842500 are adopted, and therefore sufficient cooling cannot be achieved. In addition, because the slender copper wires are not in close contact with each other in the coil ends, another problem has been that thermal conductivity in the coil ends is poor and a sufficient cooling effect cannot be achieved.
SUMMARY OF THE INVENTION
The present invention aims to solve the above problems and an object of the present invention is to provide an automotive alternator enabling temperature increases in a stator to be suppressed by constituting a predetermined region of outer surfaces of coil ends in a radial direction of a stator core facing radially outwards from the stator core and extending from a vicinity of the end surface of the stator core to apex portions into a circumferentially-smooth heat-conducting surface to raise thermal contact between the coil ends and a heat-conducting filler or between the coil ends and a tube and to achieve a superior cooling effect.
In order to achieve the above object, according to one aspect of the present invention, there is provided an automotive alternator including:
a stator having a stator core formed with slots extending axially at a predetermined pitch in a circumferential direction and a stator winding installed in the stator core;
a rotor rotatably disposed on an inner circumferential side of the stator; and
a bracket for supporting the stator and the rotor,
wherein a coil end group of the stator winding is constructed such that coil ends folded back outside the slots at an end surface of the stator core are arranged circumferentially,
wherein a predetermined region of outer surfaces of the coil ends in a radial direction of the stator core constitutes a circ
Adachi Katsumi
Asao Yoshihito
Lam Thanh
Mitsubishi Denki & Kabushiki Kaisha
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