Alternator

Details Alternator Alternator

2001-01-26

2002-10-22

Mullins, Burton S. (Department: 2834)

Electrical generator or motor structure

Dynamoelectric

Rotary

C310S071000, C310S180000, C310S201000, C310S207000

Reexamination Certificate

active

06469413

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to alternators driven by internal combustion engines. In particular, the present invention relates to a connection structure of a stator winding of an alternator to be mounted on an automotive vehicle, such as an automobile or a truck.
The entire content of the basic Japanese Patent Application from which the priority under the Convention is claimed in this application is hereby incorporated by reference into this application.
2. Description of the Related Art
In recent years, reduced sizes, increased outputs, and improved quality have been increasingly required of alternators. In order to obtain an increased output from an alternator reduced in size, it is important to distribute magnetic loading and electrical loading in a most appropriate manner and at a highest possible concentration within a limited volume.
The outputs of automotive alternators must be increased because of increasing vehicle loads while engine compartments become smaller, thereby reducing spaces for mounting the alternators. There are requirements to reduce the noise of the automotive alternators which operate all the time for supplying electricity, the noise becoming relatively large with respect to the engine noise which has been reduced in response to the requirements to reduce the noise generated toward the outside and the inside of the vehicle compartments. The automotive alternators, which operate all the time, are required to have a very high heat resistance because of their severe operating thermal condition in which the alternators are heated by a high Joule heat generated by the output current.
In order to reduce the size and increase the output of an alternator, the resistance of a stator winding must be reduced, the space factor of electrical conductors in magnetic circuits of the stator must be increased, and the bridge portions (bridge portions outside a stator core are called coil ends) of the stator winding must be set in order and be concentrated. Furthermore, the requirements for reduced noise and heat resistance, and the like must be complied with.
A structure for reducing the resistance of windings (heat loss), improving the space factor of electrical conductors, and lining up and concentrating coil ends was proposed disclosed in, for example, Japanese Patent No. 2927288, in which conductor segments formed substantially in a U-shape with short conductive wires having large cross-sections are used as strands of wire of the stator winding.
In an alternator of this type, the number of slots per pole and per phase tends to increase, that is, the alternator tends to have a plurality of sets of a three-phase alternating winding in order to comply with the requirements for reduced electrical and magnetic noise and high quality electricity supply, whereby the number of lead wires for the three-phase alternating winding is increased. When forming the three-phase alternating winding, a wiring process is necessary in which lead wires extending from the windings are drawn and are folded, and are connected. The laborious work in the wiring process is required to be alleviated. However, in the above Japanese Patent No. 2927288, the reduction of the load in the wiring process was not considered.
Therefore, the applicant of the present invention proposed a connection structure of lead wires of a stator winding in Japanese Patent Application No. 2000-011704 (a privately known but unpublished), for reducing load in a wiring process by alleviating the work for drawing and folding lead wires during a connection process of the stator winding.
FIG. 11
is a sectional view of a known automotive alternator proposed in Japanese Patent Application No. 2000-011704.
FIG. 12
is a perspective view of a stator used in the known automotive alternator.
FIG. 13
is a rear-end view explaining connections in one phase of a stator winding of the known automotive alternator.
FIG. 14
is a perspective view of a terminal assembly for three-phase alternating connections in the stator of the known automotive.
FIG. 15
is an illustration explaining a method of connection between a rectifier and the stator winding of the known automotive alternator.
FIG. 16
is a block diagram of a circuit used in the known automotive alternator.
The automotive alternator shown in
FIG. 11
includes a Lundell-type rotor
7
rotatably supported by a shaft
6
in a case
3
formed with aluminum front bracket
1
and rear bracket
2
. A stator
8
is fixed to the inner wall of the case
3
so as to cover the rotor
7
at the periphery of the rotor
7
.
The shaft
6
is rotatably supported by the front bracket
1
and the rear bracket
2
. A pulley
4
is fixed to the shaft
6
at one end thereof, for transmitting the rotational torque of an engine to the shaft
6
via a belt (not shown).
Slip rings
9
for feeding current are fixed to the other end of the shaft
6
. A pair of brushes
10
are received in a brush holder
11
disposed in the case
3
. The pair of brushes
10
are held in contact with the slip rings
9
so as to slide thereon. A regulator
18
for regulating alternating voltage generated at the stator
8
is connected to a heat sink
17
coupled with the brush holder
11
. Rectifiers
12
for rectifying alternating current generated at the stator
8
into direct current are mounted in the case
3
, the rectifiers
12
being electrically connected to the stator
8
.
The rotor
7
includes a rotor coil
13
for generating magnetic flux on passage of electric current, and a pair of pole cores
20
and
21
so as to cover the rotor coil
13
, magnetic poles being formed in the pole cores
20
and
21
by the magnetic flux generated in the rotor coil
13
. The pair of iron pole cores
20
and
21
include eight claw-shaped magnetic poles
22
and eight claw-shaped magnetic poles
23
around the peripheries of the pole cores
20
and
21
, respectively, protruding therefrom and disposed at the same angular distance from each other in the circumferential directions of the respective pole cores
20
and
21
. The pair of pole cores
20
and
21
are fastened to the shaft
6
facing each other such that the claw-shaped magnetic poles
22
and
23
intermesh. A fan unit
5
is fixed to the rotor
7
at each axial end thereof.
Intake openings
1
a
and
2
a
are formed in the front bracket
1
and the rear bracket
2
, respectively, at each axial end face. Discharge openings
1
b
and two outlets
2
b
are formed in two outer circumferential shoulder portions of the front bracket
1
and the rear bracket
2
, opposite the radial outside of the front-end and rear-end coil-end groups
16
f
and
16
r
of the stator winding
16
.
In
FIG. 12
, the stator
8
includes a cylindrical stator core
15
, made of laminated iron, provided with a plurality of slots
15
a
formed extending in the axial direction at a predetermined pitch in the circumferential direction, the stator winding
16
wound onto the stator core
15
, and insulators
19
disposed in the slots
15
a
for electrically insulating the stator winding
16
from the stator core
15
. The stator winding
16
includes twenty-four winding sub-portions in each of which one strand of wire
30
is bent back outside the slots
15
a
at both end surfaces of the stator core
15
and wound in a wave-shape so as to alternately occupy an inner layer and an outer layer in a slot depth direction within slots
15
a
at every sixth slot (equals a pitch of the magnetic poles). The stator core
15
is provided with ninety-six slots
15
a
at the same distance from each other so as to receive two sets of the three-phase alternating winding corresponding to the number of the magnetic poles which is
16
. A long copper wire having a rectangular cross-section and coated with an insulating film, for example, is used as the strand of wire.
The winding configuration of a winding phase group
161
for a phase a is described below with reference to FIG.
13
.
The winding phase group
161
for the phase a includes first to fourt

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