Electricity: magnetically operated switches – magnets – and electr – Electromagnetically actuated switches – Polarity-responsive
Reexamination Certificate
1999-12-06
2002-11-26
Donovan, Lincoln (Department: 2832)
Electricity: magnetically operated switches, magnets, and electr
Electromagnetically actuated switches
Polarity-responsive
C335S080000, C335S129000
Reexamination Certificate
active
06486760
ABSTRACT:
BACKGROUND OF INVENTION
1. Field of Invention
The present invention relates to an electromagnetic relay in a type of “slim type relay”.
2. Related Art
FIG. 1
is a perspective view showing an electromagnet used in a conventional electromagnetic relay. In the electromagnet fixing structure shown in this figure, a yoke
1011
, shaped like L, includes a bent surface portion
111
. A rectangular through hole
112
is formed in the bent surface portion
111
. A rod-like iron core
1082
is configured such hat one end of the iron core is somewhat smaller in cross section than the rectangular through hole
1112
, and the other end is provided with a flange
1122
. One end of the iron core
1082
is inserted into the through hole
1112
, thereby fixing the yoke
1011
and the iron core
1082
. The yoke
1011
and the iron core
1082
in the an electromagnet fixing structure are used together with a coil block
1013
which includes a cylindrical bobbin
1131
on which a coil
1132
is wound and a pair of coil terminals
1133
electrically connected to the coil
1132
, whereby an electromagnet is formed.
FIG. 2
is an exploded perspective view showing another conventional electromagnet, and
FIG. 3
is a perspective view showing the electromagnet shown in FIG.
2
. In the electromagnet fixing structure shown in
FIG. 2
, a piece
1091
, shaped like L, includes a bent surface portion
1111
. A rectangular through hole
1912
is formed in the bent surface portion
1911
. An iron core
1092
is shaped like L: one end of the iron core is somewhat larger in cross section than the through hole
1912
and the other end is bent. One end of the iron core
1092
is inserted into the through hole
1912
, thereby fixing the yoke
1091
and the iron core
1092
. The yoke
1091
and the iron core
1092
in the an electromagnet fixing structure, as shown in
FIGS. 2 and 3
, are used together with a coil block
1023
which includes a cylindrical bobbin
1231
on which a coil
1232
is wound and a pair of coil terminals
1233
electrically connected to the coil
1232
, whereby an electromagnet is formed.
A metal member fixing method which can fix a metal member without generating metallic powder by plastically deforming a metal member with a press-fitting punch having a spherical end is disclosed JP-A-9-314255.
In a thin-type electromagnetic relay which is high in electrical insulation and small in mounting area, an armature is generally separated from a contact block in order to secure a high electrical insulation. As a result, a card to drive a contact spring by the armature is long, and a weight of a movable portion is increased. Since its structure is designed to be thin, the coil block is also thin, so that a magnetic efficiency of the resultant electromagnetic relay is lower than that of the electromagnetic relay using a circular electromagnet.
To solve such a problem, it is necessary to improve a contact opening/closing ability as possible by increasing a contact pressure since a contact chamber is designed with an intention of space saving. To this end, it is necessary to increase an attraction force by the electromagnet. To increase the attraction force, it is desirable to reduce a magnetic resistance in a coupling portion of the iron core with the yoke where the largest magnetic loss occurs. For this reason, a called spin press-fitting is conventionally employed.
In the an electromagnet fixing structure for the yoke and the iron core shown in
FIGS. 1
to
3
, as seen from a cross sectional view shown in
FIG. 4
, it is difficult to manage the protruded portions (portion A in
FIG. 4A
) of the iron core protruded from the surface of the yoke. That is, the protruded portions of the iron cores from the yoke surfaces are not uniform in dimension. If the protruded portions of the iron cores vary in dimension, as shown in
FIG. 1
, the portions on both sides of the through hole in the bent surface (both sides in
FIG. 1
) are expanded to be deformed when the spin press-fitting is carried out. As a result, sometimes a gap is created (left) between the yoke and the iron core.
Further, in this structure, sometimes the iron core is tilted at the time of spin press-fitting, so that the exact positioning is not exact. In this case, the magnetic coupling is weakened, so that the attraction force by the electromagnet is reduced in magnitude.
FIGS. 5 through 7
show another example of a conventional electromagnetic relay. The electromagnetic relay is made up of 1) an electromagnetic block which includes an electromagnet
1201
formed such that a coil
1204
is wound on a coil bobbin
1203
with an iron core
1202
inserted into the central part of the coil bobbin, a yoke
1205
′, shaped like U, integrally formed with an upright portion
1205
a
′ magnetically coupled to a first magnetic pole
1201
a
of the electromagnet
1201
and a lateral portion
1205
b
+ extending from an end of the upright portion
1205
a
′ to a position near a second magnetic pole
1201
b
of the electromagnet
1201
, 2) an armature
1206
which is disposed facing the second magnetic pole
1201
b
of the electromagnet
1201
and rotatable about the end of the yoke
1205
′, and 3) a hinge spring
1208
for rotatably supporting the armature
1206
which the hinge spring is fixed at one end to the lateral portion
1205
b
′, of the yoke
1205
′ and at the other end to the armature
1206
, a card
1207
which is fixed to the free end of the armature
1206
and translates with the turning of the armature
1206
, 4) a pair of fixed contact plates
1209
and
1210
which are fastened at first ends to fixed contacts
1209
a
and
1210
a
which are oppositely disposed, 5) a movable contact plate
1211
with movable contacts
1211
a
fastened on both sides of one end thereof, which the movable contact plate is turned with the translation of the card
1207
, the movable contacts
11
a
being brought into contact with and separated from the fixed contacts
1209
a
and
1210
a,
6
) a base
1215
, made of insulating synthetic resin, including fixed contact plates
1209
and
1210
and the movable contact plate
211
being provided at a first end of the base
1215
, and the electromagnetic block being provided on the other end, 7) external terminals
1212
which are electrically connected to the fixed contact plates
1209
and
1210
and the movable contact plate
1211
, while protruding from the underside of the base
1215
, 8) a terminal support
1213
, made of synthetic resin, for supporting coil terminals
1214
connected to the coil
1204
located under the armature
1206
, and 9) a case
1216
, shaped like a box, which is attached to the electromagnetic block and the base
1215
in a state that the external terminal
1212
and the coil terminals
1214
are projected to exterior.
An operation of the thus constructed electromagnetic relay will be described. In a stationary sate in which no voltage is applied to between the coil terminals
1214
, no attraction force by the electromagnet
1201
is present. In this state, the armature
1206
is held at a position (referred to as “stationary position”) located apart from the second magnetic pole
1201
b
of the electromagnet
1201
. The movable contact plate
1211
is disposed on the base
1215
so as to press the movable contacts
1211
a
against the fixed contact
1209
a
, which is located close to the electromagnetic block (the normally closed side). Accordingly, when the armature
1206
is at the stationary position, the card
1207
has been moved to the left in FIG.
5
. And the movable contact plate
1211
is not pressed by the end of the card
1207
. Therefore, the movable contacts
1211
a
is held in a state that the movable contacts
1211
a
is in contact with the fixed contact
1209
a
on the normally closed side (this state will be (referred to as “stationary state”). Incidentally, a contact pressure between the movable contacts
1211
a
and the fixed contact
1209
a
is produced by a spring force of the movable contact plate
1211
made of elasti
Makino Masakatsu
Miyazaki Katsuji
Nishikawa Toyotaka
Shimomura Tsutomu
Tsuji Masaru
Donovan Lincoln
Greenblum & Bernstein P.L.C.
Matsushita Electric & Works Ltd.
Nguyen Tuyen T.
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