Electrical generator or motor structure – Dynamoelectric – Rotary
Reexamination Certificate
2002-08-12
2004-01-06
Ponomarenko, Nicholas (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Rotary
C310S06800R, C310S066000, C310S06700R, C310S069000
Reexamination Certificate
active
06674192
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a dynamoelectric machine in which a contacted part such as a slip ring, a commutator, etc., and a brush slide in contact, and particularly relates to a dynamoelectric machine such as an automotive alternator, an automotive electric motor, an automotive generator-motor, etc., provided with a rotation detecting apparatus for detecting a rotational position of a rotor.
2. Description of the Related Art
A conventional automotive generator-motor
100
, as shown in
FIG. 17
, is provided with: a housing
101
composed of a generally cup-shaped front bracket
102
and rear bracket
103
; a shaft
104
rotatably supported in the housing
101
by means of front-end and rear-end bearings
105
and
106
; a rotor
107
fixed to the shaft
104
and rotatably disposed inside the housing
101
; a stator
108
held by an inner wall surface of the housing
101
so as to surround the rotor
107
; a pair of slip rings
109
disposed on an outer circumference of an end portion of the shaft
104
projecting beyond the rear-end bearing
106
; a brush apparatus
110
disposed on an outer circumference of the slip rings
109
; a rotor position detecting apparatus
111
for detecting a relative position of the rotor
107
relative to the stator
108
; a rear cover
112
securely fastened to the rear bracket
103
so as to cover the brush apparatus
110
and the rotor position detecting apparatus
111
; and a pulley
113
fixed to a front-end end portion of the shaft
104
.
The rotor
107
is provided with: Lundell-type pole cores
115
fixed to the shaft
104
; and rotor coils
116
installed in the pole cores
115
.
The stator
108
is provided with: a stator core
117
disposed so as to be held between the front bracket
102
and the rear bracket
103
and surround the rotor
107
; and a three-phase stator coil
118
installed in the stator core
117
.
The brush apparatus
110
is provided with: a pair of brushes
119
sliding in contact with outer circumferential surfaces of the pair of slip rings
109
; and a brush holder
120
for housing the brushes
119
.
The rotor position detecting apparatus
111
, as shown in
FIGS. 18A
,
18
B, and
19
, is provided with a magnetic pole holding plate
121
, magnetic sensor poles
122
, and a position sensor
123
. The magnetic pole holding plate
121
is prepared into a disk shape using a ferromagnetic material, is securely fastened to a rear-end end surface of the shaft
104
, and rotates with the shaft
104
. The magnetic sensor poles
122
are constituted by an annular permanent magnet, being magnetized with South-seeking (S) poles and North-seeking (N) poles alternately at a uniform pitch in a circumferential direction. The magnetic sensor poles
122
are fixed to the magnetic pole holding plate
121
by means of an adhesive, etc., being disposed so as to cover a rear-end end portion of the shaft
104
in an annular shape. The position sensor
123
is constituted by a generally fan-shaped printed circuit board
125
, etc., on which an electronic circuit including three Hall elements
124
is formed. The position sensor
123
is securely fastened to an end surface of the rear bracket
103
such that the Hall elements
124
face the magnetic sensor poles
122
in close proximity thereto.
Operation of the automotive generator-motor
100
constructed in this manner when used as an electric motor will now be explained.
During starting of an engine, an alternating current is supplied sequentially to each phase of the three-phase stator coil
118
by a three-phase drive circuit (not shown), and a direct current is supplied to the rotor coil
116
by means of the brushes
119
and the slip rings
109
. Thus, the stator coil
118
and the rotor coil
116
become electromagnets, and the rotor
107
rotates inside the stator
108
together with the shaft
104
. Torque from the shaft
104
is transmitted to an output shaft of the engine by means of the pulley
113
, starting the engine.
At this time, the magnetic sensor poles
122
rotate together with the rotation of the shaft
104
. Changes in magnetic flux due to rotation of the magnetic sensor poles
122
are detected by the position sensor
123
and output to an external control apparatus (not shown) as rotor position signals. The control apparatus into which the rotor position signals are input controls the alternating current supplied sequentially to each of the phases of the three-phase stator coil
118
such that the direction of rotation of the rotor
107
is constant and a predetermined rotational frequency is achieved.
Next, operation of the automotive generator-motor
100
when used as a generator will be explained.
When an engine is started, torque from the engine is transmitted to the shaft
104
by means of the pulley
113
, rotating the shaft
104
. Thus, when a direct current is supplied to the rotor coil
116
by means of the brushes
119
and the slip rings
109
, the rotor coil
116
is excited and becomes an electromagnet. By rotating the rotor
107
inside the stator
108
in this state, an alternating current is induced sequentially in the stator coil
118
installed in the stator core
117
and a generated voltage rises rapidly. This three-phase alternating current is input into a three-phase rectifying circuit (not shown) and is rectified into a direct current. The direct-current voltage rectified by the three-phase rectifying circuit charges a battery and is supplied to an electric load.
In a conventional automotive generator-motor, because the brush apparatus
110
and the rotor position detecting apparatus
111
are disposed adjacent to an end portion of the shaft
104
projecting beyond the rear-end bearing
106
as explained above, one problem has been that abraded brush dust arising due to the sliding of the brushes
119
on the slip rings
109
may penetrate the gaps between the Hall elements
124
and the magnetic sensor poles
122
which are disposed in close proximity, preventing the rotor position detecting apparatus
111
from stably detecting the changes in the magnetic flux.
SUMMARY OF THE INVENTION
The present invention aims to solve the above problems and an object of the present invention is to provide a dynamoelectric machine enabling an angular position of a rotor to be detected with high precision by disposing contacts and a rotation detecting apparatus with a bearing interposed to prevent abrasion dust arising due to sliding motion between a contact and a contacted part from penetrating into the rotation detecting apparatus.
With the object in view, the dynamoelectric machine of the present invention includes a housing, a first bearing disposed in a first axial end portion of the housing, a second bearing disposed in a second axial end portion of the housing and a shaft rotatably supported in the housing by means of the first and second bearings. Further, the dynamoelectric machine includes a rotor composed of a rotor core fixed to the shaft and rotatably disposed inside the housing and a rotor coil installed in the rotor core, a stator composed of a stator core supported in the housing so as to surround an outer circumference of the rotor and a stator coil installed in the stator core, a contacted part fixed to an outer circumference of the shaft axially inside the first bearing and electrically connected to the rotor coil, and a contact disposed so as to contact an outer circumferential surface of the contacted part. Still further, the dynamoelectric machine includes a rotation detecting apparatus composed of a sensor rotor fixed to an end portion of the shaft projecting axially outside the first bearing, a sensor unit disposed in close proximity to the sensor rotor, and a connector unit for delivering input and output signals to and from the sensor unit.
Therefore, abrasion dust arising due to sliding motion between the contact and the contacted part does not penetrate into the rotation detecting apparatus, thereby providing a dynamoelectric machine enabling an angular position
Kusumoto Katsuhiko
Morikaku Hideki
Oohashi Atsushi
Utsumi Yoshinobu
Mohandesi Iraj A.
Ponomarenko Nicholas
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