Electrical generator or motor structure – Dynamoelectric – Rotary
Reexamination Certificate
1999-12-13
2002-02-12
Ramirez, Nestor (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Rotary
C310S124000, C310S092000
Reexamination Certificate
active
06346752
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an electromagnetic retarder with a built-in exciter, and more specifically to an electromagnetic retarder with a built-in exciter having such a construction that an eddy-current cylinder for generating braking torque by eddy current is formed by laminating a magnetic material, and an exciter core divided into a plurality of segments is used as the exciter.
2. Description of the Prior Art
FIG. 19
is a longitudinal sectional diagram illustrating the essential part of an electromagnetic retarder with a built-in exciter of a conventional type, viewed in the direction of arrows AOB of FIG.
20
.
FIG. 20
is a right-hand side view of FIG.
19
.
In
FIGS. 19 and 20
, a support disc
1
that is of a dish- or cup-shape on both sides thereof is rotatably provided between a flange
2
-
1
on the side of the output-shaft of a transmission
2
and a flange
3
-
1
on the side of a propeller-shaft
3
, as shown in FIG.
19
. The support disc
1
is formed into a shape of an open-ended dish or cup by flange members on both sides of the rim thereof, and coaxially fitted between the flange
2
-
1
on the side of the output shaft and the flange
3
-
1
on the side of the propeller shaft
3
with bolts
4
and nuts
5
.
An eddy-current cylinder
7
is disposed coaxially with the support disc
1
via a mounting disc
6
outside the support disc
1
. The eddy-current cylinder
7
is made of an iron material. In some cases, the mounting disc
6
may be formed integrally with the eddy-current cylinder
7
.
A cylindrical support member
8
made of a magnetic material is disposed in a space formed by the outside of the support disc
1
having on both side thereof members formed into an open-end disc or cup shape, and the eddy-current cylinder
7
. One end of the cylindrical support member
8
is fixedly fitted to a support plate
9
having a recess at the center thereof. The support plate
9
is fixedly fitted to an end of the transmission
2
with bolts
10
. In this case, too, the support plate
9
may be formed integrally with the support member
8
.
A pole core
11
made of a magnetic material is fitted with bolts
12
to the outer circumferential surface of the cylindrical support member
8
disposed in a space formed by the outside of the support disc
1
having on both side thereof members formed into an open-end disc or cup shape, and the eddy-current cylinder
7
. An air gap is formed between the pole core
11
and the inner circumferential surface of the eddy-current cylinder
7
. A field coil
13
is wound on the pole core
11
. An exciter core
14
is fixedly fitted to the inner circumferential surface of the support member
8
, and an exciter coil
15
is wound on a slot provided on the exciter core
14
.
On the outer circumferential surface of the support disc
1
having on both sides thereof members formed into an open-end dish- or cup-shape, provided at equal intervals are permanent magnets
16
formed into an arc-segment shape, for example, arranged in alternately different polarities. An air gap is formed between the permanent magnet
16
and the exciter core
14
. The exciter coil
15
wound on the exciter cores
14
and the permanent magnets
16
constitute an exciter.
The a-c voltage generated in the exciter coil
15
is rectified by rectifying means, and a field current flows in the field coil
13
by turning on a retarder main switch.
Numeral
17
refers to a heat shield plate for shielding the radiant heat from the eddy-current cylinder
7
caused by the heat as an eddy-current loss to inhibit temperature rise in the field coil
13
. Numeral
18
refers to a radiating fin for dissipating the heat generated in the eddy-current cylinder
7
as an eddy-current loss into the atmosphere.
The operation of the conventional type of the retarder with a built-in exciter having the aforementioned construction will be described in the following.
As the output shaft, that is, the flange
2
-
1
on the side of the output shaft of the transmission
2
is rotated, the support disc
1
, the permanent magnet
16
, the mounting disc
6
and the eddy-current cylinder
7
are also rotated en bloc. At this time, the rotation is also transmitted to the flange
3
-
1
on the side of the propeller shaft
3
.
By turning on the retarder main switch to activate the retarder, a d-c voltage obtained by rectifying the a-c voltage generated in the exciter coil
15
is applied to the field coil
13
to cause a field current to flow. As a result, the pole core
11
is magnetized to N and S poles alternately, and an eddy current is produced in the eddy-current cylinder
7
. A braking torque is generated in the direction opposite to the rotation of the eddy-current cylinder
7
between the eddy current and the field formed by the pole core
11
, applying a braking action to the rotation of the flange
2
-
1
on the side of the output shaft.
FIG. 21
is a front view of the eddy-current cylinder of the conventional type in which the mounting disc and the eddy-current cylinder are formed integrally,
FIG. 22
is a partial cross-sectional view of the side part of FIG.
21
. In the figures, the eddy-current cylinder
39
is made of a magnetic material, such as iron, has inclined radiating fins
40
on the outer circumferential surface thereof, and is equivalent to the mounting disc
6
and the eddy-current cylinder
7
described in
FIGS. 19 and 20
. The outside and inside diameters of the eddy-current cylinder
39
are Lo and Lr, respectively, and the thickness of the core (equal to the thickness of the eddy-current cylinder
7
in
FIG. 19
) is t
2
, as shown in FIG.
22
.
However, the fins of the eddy-current cylinder
7
and the eddy-current cylinder
39
, the radiating fin
18
, and the inclined radiating fin
40
shown in
FIGS. 21 and 22
as used in the electromagnetic retarder with a built-in exciter of the conventional type shown in
FIGS. 19 and 20
have been machined with a gear hobbing machine after machined with a lathe.
The conventional manufacturing method for manufacturing the eddy-current cylinders
7
and
39
having the radiating fins
18
and the inclined radiating fins
40
has had low manufacturing yield, and involved long hours for machining the radiating fins
18
and the inclined radiating fins
40
, leading to increased manufacturing cost.
Furthermore, the conventional type of the electromagnetic retarder with a built-in exciter requires splash-proof specifications to prevent water splashes during the travel of a truck from falling on the retarder, lowering the insulation of the exciter. Although there can be a method of covering the exciter coil and other parts with resin, etc. after assembly with the conventional type of the electromagnetic retarder with a built-in exciter, this method could lead to lowered productivity. To cope with this, a method of dividing the exciter core into sections, providing water-proofing measures to each section and assembling the water-proofed sections into one piece has been proposed. This method also has the risk of increasing magnetic resistance, adversely affecting the performance.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an eddy-current cylinder for electromagnetic retarders having such a construction that braking torque characteristics are improved and the manufacture of eddy-current cylinders is made easy, thereby manufacturing cost is reduced, by producing a core by laminating a magnetic material, and providing short-circuiting means allowing eddy current to flow therein in the axial direction of the eddy-current cylinder.
It is another object of the present invention to provide an exciter for electromagnetic retarders having such a construction that water proofness is imparted to the exciter coil of the retarder, and an exciter core is divided into a plurality of pieces to facilitate the assembling of the retarder with a built-in exciter while preventing the exciter performance from deteriorating due to the division of the excit
Furuse Eiichi
Osada Masahiro
Rouyama Ryuji
McGlew and Tuttle , P.C.
Perez Guillermo
Ramirez Nestor
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