U.S. patent application number 17/040955 was filed with the patent office on 2021-01-28 for electromagnetic relay.
The applicant listed for this patent is Panasonic Intellectual Property Management Co., Ltd.. Invention is credited to Akira KATO, Kazuyuki SAKIYAMA, Takehiko YAMAKAWA.
Application Number | 20210027964 17/040955 |
Document ID | / |
Family ID | 1000005193018 |
Filed Date | 2021-01-28 |
![](/patent/app/20210027964/US20210027964A1-20210128-D00000.png)
![](/patent/app/20210027964/US20210027964A1-20210128-D00001.png)
![](/patent/app/20210027964/US20210027964A1-20210128-D00002.png)
![](/patent/app/20210027964/US20210027964A1-20210128-D00003.png)
![](/patent/app/20210027964/US20210027964A1-20210128-D00004.png)
![](/patent/app/20210027964/US20210027964A1-20210128-D00005.png)
![](/patent/app/20210027964/US20210027964A1-20210128-D00006.png)
![](/patent/app/20210027964/US20210027964A1-20210128-D00007.png)
![](/patent/app/20210027964/US20210027964A1-20210128-D00008.png)
![](/patent/app/20210027964/US20210027964A1-20210128-D00009.png)
![](/patent/app/20210027964/US20210027964A1-20210128-D00010.png)
View All Diagrams
United States Patent
Application |
20210027964 |
Kind Code |
A1 |
YAMAKAWA; Takehiko ; et
al. |
January 28, 2021 |
ELECTROMAGNETIC RELAY
Abstract
An electromagnetic relay includes a fixed contact, a moving
contact, an electromagnet device, and a second coil. The moving
contact moves from a closed position where the moving contact is in
contact with the fixed contact to an open position where the moving
contact is out of contact with the fixed contact, and vice versa.
The electromagnet device includes a first coil and a mover. The
mover is actuated on receiving a magnetic flux generated when a
current flows through the first coil to move the moving contact
from one of the closed position or the open position to the other
position. The second coil gives, when a current flows through the
second coil, at least a magnetic flux, of which a direction is
opposite from a direction of the magnetic flux generated by the
first coil, to the mover.
Inventors: |
YAMAKAWA; Takehiko; (Osaka,
JP) ; SAKIYAMA; Kazuyuki; (Osaka, JP) ; KATO;
Akira; (Osaka, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Panasonic Intellectual Property Management Co., Ltd. |
Osaka |
|
JP |
|
|
Family ID: |
1000005193018 |
Appl. No.: |
17/040955 |
Filed: |
February 22, 2019 |
PCT Filed: |
February 22, 2019 |
PCT NO: |
PCT/JP2019/006686 |
371 Date: |
September 23, 2020 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01H 50/18 20130101;
H01H 50/546 20130101; H01H 47/22 20130101; H01H 50/44 20130101;
H01H 50/36 20130101 |
International
Class: |
H01H 50/54 20060101
H01H050/54; H01H 47/22 20060101 H01H047/22; H01H 50/44 20060101
H01H050/44; H01H 50/18 20060101 H01H050/18; H01H 50/36 20060101
H01H050/36 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 23, 2018 |
JP |
2018-057212 |
Claims
1. An electromagnetic relay comprising: a fixed contact; a moving
contact configured to move from a closed position where the moving
contact is in contact with the fixed contact to an open position
where the moving contact is out of contact with the fixed contact,
and vice versa; an electromagnet device including a first coil and
a mover configured to be actuated on receiving a magnetic flux
generated when a current flows through the first coil to move the
moving contact from one of the closed position or the open position
to the other position; and a second coil configured to give, when a
current flows through the second coil, at least a magnetic flux, of
which a direction is opposite from a direction of the magnetic flux
generated by the first coil, to the mover.
2. The electromagnetic relay of claim 1, further comprising a
demagnetization circuit configured to supply an alternating current
to the second coil.
3. The electromagnetic relay of claim 2, wherein the
demagnetization circuit includes a capacitor that forms a resonant
circuit with the second coil.
4. The electromagnetic relay of claim 2, wherein the
demagnetization circuit includes: a switch configured to open and
close an electrical path connecting the second coil to an AC power
supply; and a control circuit configured to control ON/OFF states
of the switch.
5. The electromagnetic relay of claim 4, wherein the control
circuit is configured to turn the switch ON when supply of a
current to the first coil is suspended.
6. The electromagnetic relay of claim 1, further comprising a yoke
configured to allow a magnetic flux generated by the first coil to
pass therethrough, wherein the second coil is separated from the
first coil by the yoke.
7. The electromagnetic relay of claim 1, wherein the second coil is
provided separately from the first coil.
Description
TECHNICAL FIELD
[0001] The present disclosure generally relates to an
electromagnetic relay, and more particularly relates to an
electromagnetic relay with the ability to turn ON and OFF a pair of
contacts.
BACKGROUND ART
[0002] Patent Literature 1 discloses an electromagnetic relay for
switching the ON/OFF states of a current using a pair of contacts.
Specifically, the electromagnetic relay of Patent Literature 1
causes a moving iron core (mover) to move with electromagnetic
force generated by energizing an excitation coil (first coil) of an
electromagnet device, thereby moving a moving contactor that a
contact device includes. This brings a moving contact of the moving
contactor into contact with a fixed contact of a fixed terminal
that the contact device includes to connect the fixed terminal and
the moving contactor together.
[0003] In the electromagnetic relay of Patent Literature 1, the
mover is placed in a magnetic field generated by energizing the
first coil. Thus, even when the first coil is no longer energized
(i.e., no longer has magnetic field), the mover may still remain
magnetized (i.e., may have remanent magnetization).
CITATION LIST
Patent Literature
[0004] Patent Literature 1: JP 2014-232668 A
SUMMARY OF INVENTION
[0005] It is therefore an object of the present disclosure to
provide an electromagnetic relay with the ability to reduce the
remanent magnetization of the mover.
[0006] An electromagnetic relay according to an aspect of the
present disclosure includes a fixed contact, a moving contact, an
electromagnet device, and a second coil. The moving contact moves
from a closed position where the moving contact is in contact with
the fixed contact to an open position where the moving contact is
out of contact with the fixed contact, and vice versa. The
electromagnet device includes a first coil and a mover. The mover
is actuated on receiving a magnetic flux generated when a current
flows through the first coil to move the moving contact from one of
the closed position or the open position to the other position. The
second coil gives, when a current flows through the second coil, at
least a magnetic flux, of which a direction is opposite from a
direction of the magnetic flux generated by the first coil, to the
mover.
BRIEF DESCRIPTION OF DRAWINGS
[0007] FIG. 1 illustrates a schematic configuration for an
electromagnetic relay according to an exemplary embodiment of the
present disclosure;
[0008] FIG. 2 is a cross-sectional view illustrating an OFF state
of the electromagnetic relay;
[0009] FIG. 3 is a cross-sectional view illustrating an ON state of
the electromagnetic relay;
[0010] FIG. 4 illustrates how the electromagnetic relay
operates;
[0011] FIG. 5 shows the magnetic properties of a mover in an
electromagnetic relay according to a comparative example;
[0012] FIG. 6 shows the magnetic properties of a mover in an
electromagnetic relay according to the exemplary embodiment of the
present disclosure;
[0013] FIG. 7 is a cross-sectional view illustrating an OFF state
of an electromagnetic relay according to a first variation of the
exemplary embodiment of the present disclosure;
[0014] FIG. 8 is a cross-sectional view illustrating an ON state of
the electromagnetic relay;
[0015] FIG. 9 illustrates how the electromagnetic relay
operates;
[0016] FIG. 10 is a cross-sectional view illustrating an OFF state
of an electromagnetic relay according to a second variation of the
exemplary embodiment of the present disclosure; and
[0017] FIG. 11 is a cross-sectional view illustrating an OFF state
of an electromagnetic relay according to a third variation of the
exemplary embodiment of the present disclosure.
DESCRIPTION OF EMBODIMENTS
[0018] Note that embodiments and their variations to be described
below are only examples of the present disclosure and should not be
construed as limiting. Rather, those embodiments and variations may
be readily modified in various manners depending on a design choice
or any other factor without departing from a true spirit and scope
of the present disclosure. It should also be noted that the
drawings to be referred to in the following description of
embodiments and their variations are all schematic representations.
That is to say, the ratio of the dimensions (including thicknesses)
of respective constituent elements illustrated on the drawings does
not always reflect their actual dimensional ratio.
[0019] (1) Configuration
[0020] (1.1) Electromagnetic Relay
[0021] An electromagnetic relay 100 according to an exemplary
embodiment includes a contact device 1 and an electromagnet device
10 as shown in FIGS. 1 and 2. The contact device 1 includes a pair
of fixed terminals 11, 12 and a moving contactor 2. The fixed
terminals 11, 12 respectively hold fixed contacts 111, 121 thereon.
The moving contactor 2 holds a pair of moving contacts 21, 22
thereon.
[0022] The electromagnet device 10 includes a first coil 101 and a
mover 15. The electromagnet device 10 is configured to have the
mover 15 attracted by a magnetic field generated by the first coil
101 when the first coil 101 is energized. Attracting the mover 15
causes the moving contacts 21, 22 held by the moving contactor 2 to
move from an open position to a closed position. As used herein,
the "open position" refers to the position of the moving contacts
21, 22 when the moving contacts 21, 22 go out of contact with the
fixed contacts 111, 121, respectively. Also, as used herein, the
"closed position" refers to the position of the moving contacts 21,
22 when the moving contacts 21, 22 come into contact with the fixed
contacts 111, 121, respectively. That is to say, the moving
contacts 21, 22 move from the closed position to the open position,
and vice versa.
[0023] In the embodiment to be described below, the electromagnetic
relay 100 is supposed to be used as a part of onboard equipment for
an electric vehicle. In that case, the contact device 1 (fixed
terminals 11, 12) is electrically connected on a path along which
DC power is supplied from a traveling battery 61 to a load (such as
an inverter) 62.
[0024] (1.2) Contact Device
[0025] Next, a configuration for the contact device 1 will be
described.
[0026] As shown in FIGS. 1 and 2, the contact device 1 includes the
pair of fixed terminals 11, 12, the moving contactor 2, and a
container 3. The fixed terminal 11 holds the fixed contact 111
thereon, and the fixed terminal 12 holds the fixed contact 121
thereon. The moving contactor 2 is a plate member made of a
metallic material with electrical conductivity. The moving
contactor 2 holds a pair of moving contacts 21, 22, which are
arranged to face the pair of fixed contacts 111, 121,
respectively.
[0027] In the following description, the direction in which the
fixed contacts 111, 121 and the moving contacts 21, 22 face each
other is defined herein to be an upward/downward direction, and the
fixed contacts 111, 121 are located on an upper side when viewed
from the moving contacts 21, 22, just for the sake of convenience.
In addition, the direction in which the pair of fixed terminals 11,
12 (i.e., the pair of fixed contact 111, 121) are arranged side by
side is defined herein to be a rightward/leftward direction, and
the fixed terminal 12 is supposed to be located on the right when
viewed from the fixed terminal 11. That is to say, in the following
description, the upward, downward, rightward, and leftward
directions are supposed to be defined on the basis of the
directions shown in FIG. 2. Furthermore, in the following
description, the direction perpendicular to both the
upward/downward direction and the rightward/leftward direction
(i.e., the direction coming out of the paper on which FIG. 2 is
depicted) is defined herein to be a forward/backward direction.
Note that these directions should not be construed as limiting a
mode of using the electromagnetic relay 100.
[0028] One (first) fixed contact 111 is held at the bottom of one
(first) fixed terminal 11, while the other (second) fixed contact
121 is held at the bottom of the other (second) fixed terminal
12.
[0029] The pair of fixed terminals 11, 12 are arranged side by side
in the rightward/leftward direction. Each of the pair of fixed
terminals 11, 12 is made of an electrically conductive metallic
material. The pair of fixed terminals 11, 12 serves as terminals
for connecting an external circuit (including the battery 61 and
the load 62) to the pair of fixed contacts 111, 121. In this
embodiment, the fixed terminals 11, 12 are supposed to be made of
copper (Cu), for example. However, this is only an example and
should not be construed as limiting. Alternatively, the fixed
terminals 11, 12 may also be made of any electrically conductive
material other than copper.
[0030] Each of the pair of fixed terminals 11, 12 is formed in the
shape of a cylinder, of which a cross section, taken along a plane
intersecting with the upward/downward direction at right angles, is
circular. The pair of fixed terminals 11, 12 are each held by the
container 3 such that part of the fixed terminal 11, 12 protrudes
from the upper surface of the container 3. Specifically, each of
the pair of fixed terminals 11, 12 is fixed onto the container 3 so
as to run through an opening cut through the upper wall of the
container 3.
[0031] The moving contactor 2 is formed in the shape of a plate
having thickness in the upward/downward direction and having a
greater dimension in the rightward/leftward direction than in the
forward/backward direction. The moving contactor 2 is arranged
under the pair of fixed terminals 11, 12 such that both
longitudinal ends thereof (i.e., both ends thereof in the
rightward/leftward direction) face the pair of fixed contacts 111,
121, respectively. Portions, respectively facing the pair of fixed
contacts 111, 121, of the moving contactor 2 are provided with the
pair of moving contacts 21, 22, respectively.
[0032] The moving contactor 2 is housed in the container 3. The
moving contactor 2 is moved up and down (i.e., in the
upward/downward direction) by the electromagnet device 10 arranged
under the container 3, thus allowing the moving contacts 21, 22
held by the moving contactor 2 to move from the closed position to
the open position, and vice versa. FIG. 2 illustrates a state where
the moving contacts 21, 22 are currently located at the open
position. In this state, the pair of moving contacts 21, 22 held by
the moving contactor 2 are out of contact with their associated
fixed contacts 111, 121, respectively. FIG. 3 illustrates a state
where the moving contacts 21, 22 are currently located at the
closed position. In this state, the pair of moving contacts 21, 22
held by the moving contactor 2 are in contact with their associated
fixed contacts 111, 121, respectively.
[0033] Therefore, when the moving contacts 21, 22 are currently
located at the closed position, the pair of fixed terminals 11, 12
are short-circuited together via the moving contactor 2. That is to
say, when the moving contacts 21, 22 are currently located at the
closed position, the moving contacts 21, 22 come into contact with
the fixed contacts 111, 121, respectively, and therefore, the fixed
terminal 11 is electrically connected to the fixed terminal 12 via
the fixed contact 111, the moving contact 21, the moving contactor
2, the moving contact 22, and the fixed contact 121. Thus, if the
fixed terminal 11 is electrically connected to one member selected
from the group consisting of the battery 61 and the load 62 and the
fixed terminal 12 is electrically connected to the other member,
the contact device 1 forms a path along which DC power is supplied
from the battery 61 to the load 62 while the moving contacts 21, 22
are located at the closed position. On the other hand, while the
moving contacts 21, 22 are located at the open position, the pair
of fixed terminals 11, 12 are opened.
[0034] In this embodiment, the moving contacts 21, 22 only need to
be held by the moving contactor 2. Therefore, the moving contacts
21, 22 may be formed by hammering out portions of the moving
contactor 2, for example, so as to form integral parts of the
moving contactor 2. Alternatively, the moving contacts 21, 22 may
be members provided separately from the moving contactor 2 and may
be secured, by welding, for example, onto the moving contactor 2.
Likewise, the fixed contacts 111, 121 only need to be held by the
fixed terminals 11, 12, respectively. Therefore, the fixed contacts
111, 121 may form integral parts of the fixed terminals 11, 12,
respectively. Alternatively, the fixed contacts 111, 121 may be
members provided separately from the fixed terminals 11, 12 and may
be secured, by welding, for example, onto the fixed terminals 11,
12, respectively.
[0035] The container 3 houses the pair of fixed contacts 111, 121
and the moving contactor 2. The container 3 only needs to be formed
in the shape of a box that houses the pair of fixed contacts 111,
121 and the moving contactor 2. Thus, the container 3 does not have
to be formed in the shape of a hollow rectangular parallelepiped as
in this embodiment but may also be formed in the shape of a hollow
elliptic cylinder or a hollow polygonal column, for example. That
is to say, as used herein, the "box shape" refers to any shape in
general which has a space to house the pair of fixed contacts 111,
121 and the moving contactor 2 inside, and therefore, does not have
to be a rectangular parallelepiped shape. The container 3 is formed
by joining together a housing, a flange, and an upper plate of a
yoke 13 of the electromagnet device 10 to be described later. In
FIG. 2, the structure of the electromagnet device 100 is
illustrated in a simplified form and illustration of the housing,
the flange, and the upper plate of the yoke 13 is omitted. The same
statement applies to FIGS. 3, 7, 8, 10, and 11 as well.
[0036] The housing may be made of a ceramic material such as
aluminum oxide (alumina). The housing is formed in the shape of a
hollow rectangular parallelepiped, of which the dimension is
greater in the rightward/leftward direction than in the
forward/backward direction. The lower surface of the housing is
open. The upper surface of the housing has a pair of openings to
pass the pair of fixed terminals 11, 12 therethrough. The pair of
openings may be formed in a circular shape, for example, and runs
through the upper wall of the housing along the thickness thereof
(i.e., in the upward/downward direction). The fixed terminal 11 is
passed through one opening and the fixed terminal 12 is passed
through the other opening. The pair of fixed terminals 11, 12 and
the housing are joined together by brazing, for example.
Furthermore, the housing does not have to be made of a ceramic
material but may also be made of an electrical insulating material
such as glass or resin or may even be made of a metallic material.
In any case, the housing is suitably made of a non-magnetic
material so as not to be magnetized with magnetism and turn into a
magnetic body.
[0037] The flange is made of a non-magnetic metallic material,
which may be an austenitic stainless steel such as SUS304. The
flange may be formed in the shape of a hollow rectangular
parallelepiped elongated in the rightward/leftward direction. The
upper and lower surfaces of the flange are open. The flange is
arranged between the housing and the electromagnet device 10. The
flange is hermetically bonded to the housing and the upper plate of
the yoke 13. This turns the internal space, surrounded with the
housing, the flange, and the upper plate of the yoke 13, of the
contact device 1 into a hermetically sealed space. The flange does
not have to be made of a non-magnetic material but may also be made
of an alloy, such as 42 alloy, including iron as a main
component.
[0038] (1.3) Electromagnet Device
[0039] Next, a configuration for the electromagnet device 10 will
be described.
[0040] The electromagnet device 10 is arranged under the moving
contactor 2 as shown in FIGS. 1 and 2. The electromagnet device 10
includes a first coil 101, a second coil 102, a stator 14, and a
mover 15. That is to say, in this embodiment, the second coil 102
is provided separately from the first coil 101. When the first coil
101 is energized, the electromagnet device 10 has the mover 15
attracted toward the stator 14 by a magnetic field generated by the
first coil 101, thereby moving the mover 15 upward.
[0041] In this embodiment, the electromagnet device 10 includes not
only the first coil 101, the second coil 102, the stator 14, and
the mover 15 but also a yoke 13, a shaft 16, a holder 17, a contact
pressure spring 18, and a return spring 19 as well. The
electromagnet device 10 further includes a cylindrical body and a
coil bobbin. Note that the structure of the electromagnet device 10
is illustrated in a simplified form in FIG. 2 and illustration of
the cylindrical body and the coil bobbin is omitted from FIG. 2.
The same statement applies to FIGS. 3, 7, 8, 10, and 11 as
well.
[0042] The stator 14 is a fixed iron core formed in the shape of a
cylinder protruding downward from a central region of the lower
surface of the upper plate of the yoke 13 (from the bottom wall of
the container 3 on the drawings). The upper end portion of the
stator 14 is secured to the upper plate of the yoke 13.
[0043] The mover 15 is a moving iron core also formed in the shape
of a cylinder. The mover 15 is arranged under the stator 14 such
that the upper end face of the mover 15 faces the lower end face of
the stator 14. The mover 15 is configured to be movable in the
upward/downward direction. Specifically, the mover 15 moves back
and forth between a first position where the upper end face thereof
is out of contact with the lower end face of the stator 14 (see
FIG. 2) and a second position where the upper end face thereof is
in contact with the lower end face of the stator 14 (see FIG.
3).
[0044] The first coil 101 is arranged under the container 3 such
that its center axis is aligned with the upward/downward direction.
The stator 14 and the mover 15 are arranged inside the first coil
101. One end of the first coil 101 is electrically connected to a
first switch 41 and the other end of the first coil 101 is
electrically connected to a DC power supply 71. The first coil 101
is formed by winding an electrically conductive wire around a coil
bobbin made of a synthetic resin. The DC power supply 71 may have
any configuration for supplying a DC current to the first coil 101
and may include a DC/DC converter circuit or an AC/DC converter
circuit, for example.
[0045] In this embodiment, the first switch 41 forms part of a
driver circuit 4 for driving the first coil 101. The first switch
41 is controlled by an external circuit to have its ON/OFF states
switched, thereby opening and closing an electrical path connecting
the first coil 101 to the DC power supply 71. Specifically, when
the first switch 41 is in ON state, a direct current flows from the
DC power supply 71 into the first coil 101, thereby energizing the
first coil 101 (i.e., driving the first coil 101). On the other
hand, when the first switch 41 is in OFF state, the supply of the
direct current from the DC power supply 71 to the first coil 101 is
suspended, thereby canceling the energized state of the first coil
101.
[0046] The second coil 102 is arranged inside the first coil 101
such that its center axis is aligned with the upward/downward
direction. The mover 15 is arranged inside the second coil 102. A
demagnetization circuit 5 is electrically connected to both ends of
the second coil 102. The second coil 102 is formed by winding an
electrically conductive wire around a coil bobbin made of a
synthetic resin. Note that the coil bobbin for the first coil 101
and the coil bobbin for the second coil 102 are different from each
other.
[0047] The demagnetization circuit 5 is implemented as a series
circuit of a capacitor 51 and a resistor 52. The capacitor 51 and
the resistor 52 form, along with the second coil 102, a series
resonant circuit. In other words, the demagnetization circuit 5
includes the capacitor 51 that forms, along with the second coil
102, a resonant circuit. In this embodiment, an alternating current
is allowed to flow through the second coil 102 by utilizing the
resonance between the second coil 102 and the demagnetization
circuit 5 (including the capacitor 51 and the resistor 52). That is
to say, the demagnetization circuit 5 supplies the alternating
current to the second coil 102. The operation of the
demagnetization circuit 5 will be described in detail later in the
"(2.2) Demagnetization operation" section.
[0048] The yoke 13 is arranged to surround the first coil 101. The
yoke 13 forms, along with the stator 14 and the mover 15, a
magnetic circuit, through which a magnetic flux .phi.1 (see FIG.
3), produced when the first coil 101 is energized, passes. In other
words, the magnetic flux .phi.1 generated by the first coil 101
passes through the yoke 13. Thus, the yoke 13, the stator 14, and
the mover 15 are all made of a magnetic material (such as a
ferromagnetic body). As described above, the upper plate of the
yoke 13 forms part of the bottom wall of the container 3.
[0049] The shaft 16 is made of a non-magnetic material. The shaft
16 is formed in the shape of a round rod extending in the
upward/downward direction. The shaft 16 transmits the driving
force, generated by the electromagnet device 10, to the contact
device 1 provided over the electromagnet device 10. The shaft 16
passes through the inside of the contact pressure spring 18, a
through hole provided through a central region of the upper plate
of the yoke 13, the inside of the stator 14, and the inside of the
return spring 19 to have the lower end thereof fixed onto the mover
15. The holder 17 is fixed at the upper end of the shaft 16.
[0050] The holder 17 has the shape of a rectangular cylinder, of
which the right and left surfaces are both open. The holder 17 is
combined with the moving contactor 2 such that the moving contactor
2 runs through the holder 17 in the rightward/leftward direction.
The contact pressure spring 18 is arranged between the bottom wall
of the holder 17 and the moving contactor 2. That is to say, a
middle portion in the rightward/leftward direction of the moving
contactor 2 is held by the holder 17. An upper end portion of the
shaft 16 is fixed onto the holder 17. When the first coil 101 is
energized, the shaft 16 is pushed upward as the mover 15 moves
upward. Thus, the holder 17 also moves upward. As a result of this
movement, the moving contactor 2 moves upward to bring the pair of
moving contacts 21, 22 to the closed position where the pair of
moving contacts 21, 22 are in contact with the pair of fixed
contacts 111, 121, respectively.
[0051] The contact pressure spring 18 is arranged between the lower
surface of the moving contactor 2 and the upper surface of the
bottom wall of the holder 17. The contact pressure spring 18 is a
coil spring that biases the moving contactor 2 upward. One end of
the contact pressure spring 18 is connected to the lower surface of
the moving contactor 2, while the other end of the contact pressure
spring 18 is connected to the upper surface of the bottom wall of
the holder 17.
[0052] At least part of the return spring 19 is arranged inside the
stator 14. The return spring 19 is a coil spring that biases the
mover 15 downward (toward the first position). One end of the
return spring 19 is connected to the upper end face of the mover 15
and the other end of the return spring 19 is connected to the upper
plate of the yoke 13.
[0053] The cylindrical body is formed in the shape of a bottomed
cylinder with an open upper surface. The upper end portion of the
cylindrical body is bonded onto the lower surface of the upper
plate of the yoke 13. This allows the cylindrical body to restrict
the direction of movement of the mover 15 to the upward/downward
direction and also define the first position of the mover 15. The
cylindrical body is hermetically bonded onto the lower surface of
the upper plate of the yoke 13. This allows, even when a through
hole is provided through the upper plate of the yoke 13, the
internal space, surrounded with the housing, the flange, and the
upper plate of the yoke 13, of the contact device 1 to be kept
sealed hermetically.
[0054] (2) Operation
[0055] Next, it will be described briefly how the electromagnetic
relay 100 according to this embodiment operates.
[0056] (2.1) Basic Operation
[0057] First, a basic operation of the electromagnetic relay 100
will be described. While the first switch 14 is in OFF state and
the first coil 101 is supplied with no electric current (i.e., not
energized), no magnetic attractive force is generated between the
mover 15 and the stator 14. Thus, in such a situation, the mover 15
is located at the first position under the spring force applied by
the return spring 19. At this time, the shaft 16 and the holder 17
have been pulled down to restrict the upward movement of the moving
contactor 2. This causes the pair of moving contacts 21, 22 held by
the moving contactor 2 to be located at the open position, which is
the lower end position of their movable range. This brings the pair
of moving contacts 21, 22 out of contact with the pair of fixed
contacts 111, 121, respectively, thus turning the contact device 1
open. In this state, the pair of fixed terminals 11, 12 are
electrically nonconductive with each other.
[0058] On the other hand, when the first switch 41 is turned ON by
an external circuit, a direct current is supplied from the DC power
supply 71 to the first coil 101. Thus, when the first coil 101 is
energized (i.e., supplied with an electric current), magnetic
attractive force is generated between the mover 15 and the stator
14, thus causing the mover 15 to be pulled upward by overcoming the
spring force applied by the return spring 19 to reach the second
position. At this time, the shaft 16 and the holder 17 are pushed
upward, thus lifting the restriction imposed by the shaft 16 and
the holder 17 against the upward movement of the moving contactor
2. Then, the contact pressure spring 18 biases the moving contactor
2 upward, thus causing the moving contacts 21, 22 held by the
moving contactor 2 to move toward the closed position at the upper
end of their movable range. This brings the pair of moving contacts
21, 22 into contact with the pair of fixed contacts 111, 121,
respectively, thus turning the contact device 1 closed. In this
state, the contact device 1 is closed, and therefore, the pair of
fixed terminals 11, 12 are electrically conductive with each other.
In this state, power is supplied from the battery 61 to the load
62.
[0059] Next, when power stops being supplied from the battery 61 to
the load 62 due to an excessive amount of current flowing through
the load 62 and its surrounding parts, for example, the external
circuit turns the first switch 41 OFF. Then, the supply of a direct
current from the DC power supply 71 to the first coil 101 is
suspended, thus making the first coil 101 electrically
nonconductive. In that case, the pair of moving contacts 21, 22
goes out of contact with the pair of fixed contacts 111, 121,
respectively, as described above, thus turning the contact device 1
open. In this state, the pair of fixed terminals 11, 12 becomes
electrically nonconductive with each other, thus suspending the
supply of power from the battery 61 to the load 62.
[0060] This allows the electromagnet device 10 to control the
magnetic attractive force to be applied onto the mover 15 by
selectively energizing the first coil 101 and to generate driving
force for switching the state of the contact device 1 from the open
state to the closed state, and vice versa, by moving the mover 15
up and down in the upward/downward direction. In other words, the
mover 15 is actuated on receiving the magnetic flux .phi.1 (see
FIG. 3) generated when a current flows through the first coil 101,
thus moving the moving contacts 21, 22 from one of the closed
position or the open position (e.g., the open position in this
example) to the other position (e.g., the closed position in this
example).
[0061] (2.2) Demagnetization Operation
[0062] Next, a demagnetization operation using the second coil 102
will be described with reference to FIG. 4. In FIG. 4, the "coil
current" indicates the amounts of currents flowing through the
first coil 101 and the second coil 102. Specifically, the dotted
line shown in FIG. 4 indicates the amount of current I1 flowing
through the first coil 101 (hereinafter referred to as a "first
current"), while the solid line shown in FIG. 4 indicates the
amount of current I2 flowing through the second coil 102
(hereinafter referred to as a "second current"). The same statement
also applies to FIG. 9 to be referred to later. Also, in FIG. 4,
"displacement" indicates the displacement of the mover 15.
Specifically, in FIG. 4, P1 indicates that the mover 15 is located
at the first position and P2 indicates that the mover 15 is located
at the second position.
[0063] First, at a time t1, when the first switch 41 turns ON to
energize the first coil 101, the first current I1 flows through the
first coil 101. Thus, the magnetic flux .phi.1 generated by the
first coil 101 produces magnetic attractive force between the mover
15 and the stator 14 to cause the mover 15 to move from the first
position to the second position. At this time, the magnetic flux
.phi.1 generated by the first coil 101 is interlinked with the
second coil 102 provided inside the yoke 13, thus causing an
induced current (second current) I2 to flow through the second coil
102. In this case, the second current I2 is so much smaller than
the first current I1 that the magnetic repulsion produced by the
second current I2 hardly affects the upward movement of the mover
15.
[0064] Next, at a time t2, the first switch 41 turns OFF to cancel
the energized state of the first coil 101. Then, the supply of the
first current I1 to the first coil 101 is suspended. This causes
the first coil 101 to stop generating the magnetic flux .phi.1.
Thus, the magnetic attractive force between the mover 15 and the
stator 14 is lost. As a result, the mover 15 moves from the second
position to the first position under the spring force applied by
the return spring 19.
[0065] With this regard, the mover 15 is magnetized by receiving
the magnetic flux .phi.1 generated by the first coil 101. However,
even when the energized state of the first coil 101 is canceled
after that, the mover 15 may still be magnetized in some cases. In
the following description, the mover 15 is supposed to be have
remanent magnetization when the energize state of the first coil
101 is canceled.
[0066] When the first coil 101 stops generating the magnetic flux
.phi.1 at the time t2, the magnetic flux .phi.1 interlinked with
the second coil 102 changes, thus causing the induced current
(second current) I2 to flow through the second coil 102. Also, as
the mover 15 starts returning from the second position toward the
first position at the time t2, the mover 15 with the remanent
magnetization moves inside the second coil 102, thus causing the
induced current (second current) I2 to flow through the second coil
102. Then, resonance is produced between the second coil 102 and
the demagnetization circuit 5 (including the capacitor 51 and the
resistor 52) to cause an alternating current to flow through the
second coil 102. The alternating current flowing through the second
coil 102 induces the second coil 102 to alternately generate a
magnetic flux having the same direction as the magnetic flux .phi.1
generated by the first coil 101 and a magnetic flux having the
opposite direction from the magnetic flux .phi.1. In other words,
when the current flows through the second coil 102, the second coil
102 gives at least a magnetic flux, of which the direction is
opposite from that of the magnetic flux .phi.1 generated by the
first coil 101, to the mover 15.
[0067] As can be seen, the mover 15 is placed in a magnetic field
generated by the alternating current flowing through the second
coil 102 which has a direction that changes cyclically. Therefore,
the remanent magnetization of the mover 15 decreases with the
passage of time. The strength of the magnetic field generated by
the second coil 102 also decreases with time, as the electrical
energy is consumed by the resistor 52.
[0068] Next, the advantages of the electromagnetic relay 100
according to this embodiment over an electromagnetic relay as a
comparative example will be described. The electromagnetic relay
according to the comparative example includes no second coil 102 or
demagnetization circuit 5, which is a major difference from the
electromagnetic relay 100 according to this embodiment.
[0069] In the electromagnetic relay according to the comparative
example, the mover may exhibit the magnetic properties shown in
FIG. 5, for example. In FIG. 5, the ordinate indicates the flux
density of the magnetic flux passing through the mover, while the
abscissa indicates the strength of the magnetic field in which the
mover is placed. In the electromagnetic relay according to the
comparative example, when placed in a magnetic field generated when
the first coil is energized, the mover is magnetized (see the state
A1 shown in FIG. 5). Thereafter, when the energized state of the
first coil is canceled, the magnetic field strength goes zero again
but magnetization remains in the mover (see the state A2 shown in
FIG. 5). While the mover has such remanent magnetization, the mover
tends to be attracted toward the stator easily, thus taking a long
time to perform the operation of opening and closing the contact
device (e.g., the operation of moving the pair of moving contacts
from the closed position to the open position in this case). That
is to say, in the electromagnetic relay according to the
comparative example, the remanent magnetization of the mover
increases the chances of causing a decline in the responsivity of
the opening/closing operation of the contact device.
[0070] In contrast, in the electromagnetic relay 100 according to
this embodiment, the mover 15 may exhibit the magnetic properties
shown in FIG. 6, for example. In FIG. 6, the ordinate indicates the
flux density of the magnetic flux passing through the mover 15,
while the abscissa indicates the strength of the magnetic field in
which the mover 15 is placed. Also, in the first and fourth
quadrants shown in FIG. 6, the direction of the magnetic field
where the mover 15 is placed is the same as the direction of the
magnetic flux .phi.1 generated by the first coil 101 which passes
through the mover 15 (hereinafter referred to as a "first
direction"). In the second and third quadrants, the direction of
the magnetic field where the mover 15 is placed is opposite from
the first direction (and will be hereinafter referred to as a
"second direction").
[0071] As in the electromagnetic relay according to the comparative
example, when placed in the magnetic field generated by energizing
the first coil 101, the mover 15 of the electromagnetic relay 100
according to this embodiment is also magnetized (see the state B1
shown in FIG. 6). Thereafter, when the energized state of the first
coil 101 is canceled, the magnetic field strength goes zero again
but magnetization remains in the mover 15 (see the state B2 shown
in FIG. 6). In the electromagnetic relay 100 according to this
embodiment, however, an alternating current flows through the
second coil 102 after the state B2, thus alternately placing the
mover 15 in a magnetic field with the first direction and a
magnetic field with the second direction. This causes the mover 15
to make a state transition from the state B2 to the state B3, the
state B4, . . . and then the state B13 in this order with the
passage of time as shown in FIG. 6. Thus, the remanent
magnetization of the mover 15 decreases with the passage of
time.
[0072] As can be seen from the foregoing description, the
electromagnetic relay 100 according to this embodiment achieves the
advantage of reducing the remanent magnetization of the mover 15 by
placing the mover 15 in the magnetic field generated by the second
coil 102. This allows the electromagnetic relay 100 according to
this embodiment to achieve the advantage of reducing the chances of
the mover 15 having remanent magnetization that would cause a
decline in the responsivity in the opening and closing operations
of the contact device 1, compared to the electromagnetic relay
according to the comparative example.
[0073] (3) Variations
[0074] Next, first to third variations of the exemplary embodiment
described above will be enumerated one after another. Note that any
of the variations to be described below may be adopted in
combination with the exemplary embodiment as appropriate.
[0075] (3.1) First Variation
[0076] In the electromagnetic relay 100a according to a first
variation, the second coil 102 is separated from the first coil 101
by a yoke 103 as shown in FIGS. 7 and 8, which is a major
difference from the electromagnetic relay 100 according to the
exemplary embodiment described above. Specifically, according to
this variation, the yoke 103 has a recess 131, which forms a space
surrounding the mover 15 at the first position and in which the
second coil 102 is arranged. Thus, in this variation, the first
coil 101 is arranged inside the space surrounded with the yoke 13,
while the second coil 102 is arranged outside that space.
[0077] In this variation, when the first coil 101 is energized, the
magnetic flux .phi.1 generated by the first coil 101 tends to pass
as shown in FIG. 8 through the yoke 13 with smaller magnetic
resistance than the space where the second coil 102 is arranged.
That is to say, this variation reduces the chances of the magnetic
flux .phi.1 generated by the first coil 101 being interlinked with
the second coil 102, compared with the exemplary embodiment
described above.
[0078] Next, it will be described briefly with reference to FIG. 9
how the electromagnetic relay 100a according to this variation
performs a demagnetization operation. First, when energized at a
time t1, the first coil 101 generates a magnetic flux .phi.1.
According to this variation, the magnetic flux .phi.1 generated by
the first coil 101 is less likely to be interlinked with the second
coil 102, and therefore, no or almost no induced current (second
current) I2 flows through the second coil 102. Likewise, when the
energized state of the first coil 101 is canceled at a time t2, the
magnetic flux does not change, or hardly changes, at the second
coil 102, and therefore, no or almost no induced current (second
current) I2 flows through the second coil 102. Meanwhile, as the
mover 15 with the remanent magnetization moves inside the second
coil 102 at the time t2, an induced current (second current) I2
flows through the second coil 102. In this manner, a
demagnetization operation is performed.
[0079] As can be seen, according to this variation, as the mover 15
with the remanent magnetization moves inside the second coil 102,
an induced current (second current) I2 flows through the second
coil 102. Thus, the second coil 102 is driven to reduce the
remanent magnetization of the mover 15. Therefore, according to
this variation, the magnetic attractive force hardly affects the
movement of the mover 15. In addition, when the mover 15 has no
remanent magnetization, the second coil 102 is less likely driven.
Consequently, the electromagnetic relay 100a according to this
variation achieves the advantage of reducing the remanent
magnetization of the mover 15 more efficiently than the
electromagnetic relay 100 according to the exemplary embodiment
described above does.
[0080] (3.2) Second Variation
[0081] In an electromagnetic relay 100b according to a second
variation, the demagnetization circuit 5 is made up of a second
switch 53 and a control circuit 54 as shown in FIG. 10, instead of
the series circuit of the capacitor 51 and the resistor 52, which
is a major difference from the electromagnetic relay 100 according
to the exemplary embodiment described above. The second switch 53
is provided on an electrical path connecting an AC power supply 72
to the second coil 102 to open and close the electrical path. The
control circuit 54 controls the ON/OFF states of the second switch
53. The AC power supply 72 only needs to be configured to supply an
alternating current to the second coil 102 and may include a DC
power supply and an inverter circuit for receiving DC power from
the DC power supply and outputting AC power. The alternating
current output from the AC power supply 72 may have a sinusoidal
wave or a rectangular wave, whichever is appropriate.
[0082] According to this variation, when the supply of a current to
the first coil 101 is suspended, the control circuit 54 turns the
second switch 53 ON. That is to say, according to this variation, a
demagnetization operation is performed by supplying an alternating
current to the second coil 102 while the first coil 101 is
nonconductive. This implementation is realizable by having the
control circuit 54 control the ON/OFF states of the second switch
53 in association with the ON/OFF states of the first switch 41 of
the driver circuit 4. That is to say, the control circuit 54 may
turn the second switch 53 ON while the first switch 41 is OFF and
turn the second switch 53 OFF while the first switch 41 is ON.
[0083] As can be seen, according to this variation, turning the
second switch 53 ON or OFF at an arbitrary timing using the control
circuit 54 allows an alternating current to be supplied to the
second coil 102 at the arbitrary timing. Thus, the electromagnetic
relay 100b according to this variation achieves the advantage of
reducing the remanent magnetization of the mover 15 at any timing.
In addition, this variation also achieves the advantage of reducing
the effect of the magnetic attractive force on the movement of the
mover 15, compared to turning the second switch 53 ON while the
first coil 101 is energized.
[0084] (3.3) Third Variation
[0085] In an electromagnetic relay 100c according to a third
variation, the first coil 101 also serves as the second coil 102 as
shown in FIG. 11, which is a major difference from the
electromagnetic relay 100 according to the exemplary embodiment
described above. That is to say, the electromagnetic relay 100c
according to this variation does not include the second coil 102
provided separately from the first coil 101. In this variation, the
first coil 101 also serves as the second coil 102.
[0086] In this variation, the first switch 41 is replaced with a
c-contact third switch 8. A common terminal 81 of the third switch
8 is electrically connected to one end of the first coil 101. A
normally open terminal 82 of the third switch 8 is electrically
connected to the cathode of the DC power supply 71 and a normally
closed terminal 83 thereof is electrically connected to one
terminal of the demagnetization circuit 5 (including the capacitor
51 and the resistor 52). The other terminal of the demagnetization
circuit 5 and the anode of the DC power supply 71 are electrically
connected to the other end of the first coil 101.
[0087] In this variation, while the first coil 101 is electrically
nonconductive, the demagnetization circuit 5 is connected to the
first coil 101. Connecting the first coil 101 to the DC power
supply 71 by controlling the third switch 8 allows the first coil
101 to be switched from the electrically nonconductive state to an
electrically conductive state. Thereafter, connecting the first
coil 101 to the demagnetization circuit 5 again by controlling the
third switch 8 allows the first coil 101 to be switched from the
electrically conductive state to the electrically nonconductive
state. At this time, if the mover 15 has remanent magnetization,
the movement of the mover 15 with remanent magnetization inside the
second coil 102 causes an induced current (second current) I2 to
flow through the second coil 102, thus having a demagnetization
operation performed.
[0088] As can be seen, the electromagnetic relay 100c according to
this variation achieves the advantage of allowing a single coil to
perform both the function of the first coil 101 and the function of
the second coil 102.
[0089] (3.4) Other Variations
[0090] Next, other variations of the exemplary embodiment described
above will be enumerated one after another. Note that the
variations to be described below may be adopted in combination with
the exemplary embodiment described above (including the first to
third variations thereof) as appropriate.
[0091] In the exemplary embodiment described above, the
demagnetization circuit 5 includes not only the capacitor 51 but
also the resistor 52 as well. However, this is only an example of
the present disclosure and should not be construed as limiting.
That is to say, the demagnetization circuit 5 including only the
capacitor 51 may still form a resonant circuit with the second coil
102, and therefore, may include no resistors 52.
[0092] In the exemplary embodiment described above, the
demagnetization circuit 5 may be either built in, or provided as an
external circuit for, the electromagnetic relay 100, whichever is
appropriate.
[0093] In the first variation described above, the second coil 102
is separated by the yoke 13 from the first coil 101 and is
magnetically independent of the first coil 101. However, this is
only an example of the present disclosure and should not be
construed as limiting. That is to say, the electromagnetic relay
100a may be configured to make the first coil 101 and the second
coil 102 magnetically independent of each other by using a member
other than the yoke 13.
[0094] In the second variation described above, the demagnetization
circuit 5 is configured to supply an alternating current to the
second coil 102 by being connected to the AC power supply 72.
However, this is only an example of the present disclosure and
should not be construed as limiting. Alternatively, the
demagnetization circuit 5 may also be configured to supply a direct
current to the second coil 102 by being connected to a DC power
supply, for example.
[0095] According to the third variation described above, the
demagnetization circuit 5 is implemented as a so-called "passive
circuit" for reducing the remanent magnetization of the mover 15 by
using an induced current generated by the movement of the mover 15
magnetized. However, this is only an example of the present
disclosure and should not be construed as limiting. Alternatively,
the demagnetization circuit 5 may also be implemented as a
so-called "active circuit" for reducing the remanent magnetization
of the mover 15 by using an alternating current actively supplied
from the AC power supply 72 as in the second variation described
above. This implementation is realizable by replacing the series
circuit of the capacitor 51 and the resistor 52 with an AC power
supply 72. In addition, according to this implementation, the
demagnetization circuit 5 is made up of the third switch 8 and a
control circuit for the third switch 8.
[0096] In the exemplary embodiment described above, the container 3
is configured to hold the fixed terminals 11, 12 with the fixed
terminals 11, 12 partially exposed. However, this configuration is
only an example and should not be construed as limiting.
Alternatively, the container 3 may house the fixed terminals 11, 12
entirely inside itself. That is to say, the container 3 only needs
to be configured to house the fixed contacts 111, 121 and the
moving contactor 2 to say the least.
[0097] Furthermore, in the exemplary embodiment described above,
the electromagnetic relay 100 is supposed to be a so-called
"normally OFF" electromagnetic relay, of which the pair of moving
contacts 21, 22 are located at the open position while the first
coil 101 is not energized. However, this is only an example and
should not be construed as limiting. Alternatively, the
electromagnetic relay 100 may also be a normally ON electromagnetic
relay.
[0098] Furthermore, in the exemplary embodiment described above,
the number of moving contacts held by the moving contactor 2 is
two. However, this is only an example and should not be construed
as limiting. The number of the moving contacts held by the moving
contactor 2 may also be one or even three or more. Likewise, the
number of the fixed terminals (and fixed contacts) does not have to
be two but may also be one or even three or more.
[0099] The electromagnetic relay 100 according to the exemplary
embodiment described above includes the holder 17. However, this is
only an example of the present disclosure and should not be
construed as limiting. Alternatively, the electromagnetic relay 100
may have no holders. In that case, the moving contactor 2 is fixed
at the upper end portion of the shaft 16. Also, the contact
pressure spring 18 is arranged between the lower surface of the
moving contactor 2 and the upper surface of the bottom wall of the
container 3.
[0100] Furthermore, in the exemplary embodiment described above,
the contact device 1 is implemented as a plunger type contact
device. Alternatively, the contact device 1 may also be implemented
as a hinged contact device.
[0101] (Resume)
[0102] As can be seen from the foregoing description, an
electromagnetic relay (100, 100a, 100b, 100c) according to a first
aspect includes a fixed contact (111, 121), a moving contact (21,
22), an electromagnet device (10), and a second coil (102). The
moving contact (21, 22) moves from a closed position where the
moving contact (21, 22) is in contact with the fixed contact (111,
121) to an open position where the moving contact (21, 22) is out
of contact with the fixed contact (111, 121), and vice versa. The
electromagnet device (10) includes a first coil (101) and a mover
(15). The mover (15) is actuated on receiving a magnetic flux
(.phi.1) generated when a current flows through the first coil
(101) to move the moving contact (21, 22) from one of the closed
position or the open position to the other position. The second
coil (102) gives, when a current flows through the second coil
(102), at least a magnetic flux, of which a direction is opposite
from a direction of the magnetic flux (.phi.1) generated by the
first coil (101), to the mover (15).
[0103] This aspect achieves the advantage of reducing the remanent
magnetization of the mover (15).
[0104] An electromagnetic relay (100, 100a, 100b, 100c) according
to a second aspect, which may be implemented in conjunction with
the first aspect, further includes a demagnetization circuit (5) to
supply an alternating current to the second coil (102).
[0105] This aspect allows the mover (15) to be placed in a magnetic
field, of which the direction changes cyclically, thus achieving
the advantage of facilitating reduction in the remanent
magnetization of the mover (15).
[0106] In an electromagnetic relay (100, 100a, 100c) according to a
third aspect, which may be implemented in conjunction with the
second aspect, the demagnetization circuit (5) includes a capacitor
(51) that forms a resonant circuit with the second coil (102).
[0107] This aspect achieves the advantage of reducing the remanent
magnetization of the mover (15) without providing any power supply
for supplying an alternating current.
[0108] In an electromagnetic relay (100b) according to a fourth
aspect, which may be implemented in conjunction with the second
aspect, the demagnetization circuit (5) includes a switch (second
switch) (53) and a control circuit (54). The switch (53) opens and
closes an electrical path connecting the second coil (102) to an AC
power supply (72). The control circuit (54) controls ON/OFF states
of the switch (53).
[0109] This aspect allows an alternating current to be supplied to
the second coil (102) at an arbitrary timing, thus achieving the
advantage of reducing the remanent magnetization of the mover (15)
at an arbitrary timing.
[0110] In an electromagnetic relay (100b) according to a fifth
aspect, which may be implemented in conjunction with the fourth
aspect, the control circuit (54) turns the switch (53) ON when
supply of a current to the first coil (101) is suspended.
[0111] This aspect achieves the advantage of reducing, compared to
the case of turning the switch (53) ON when the first coil (101) is
energized, the effect of magnetic attractive force on the movement
of the mover (15).
[0112] An electromagnetic relay (100a, 100b) according to a sixth
aspect, which may be implemented in conjunction with any one of the
first to fifth aspects, further includes a yoke (13) to allow a
magnetic flux (.phi.1) generated by the first coil (101) to pass
therethrough. The second coil (102) is separated from the first
coil (101) by the yoke (13).
[0113] This aspect reduces the chances of the magnetic flux
(.phi.1) generated by the first coil (101) being interlinked with
the second coil (102), thus achieving the advantage of reducing the
effect of the magnetic attractive force on the movement of the
mover (15).
[0114] In an electromagnetic relay (100, 100a, 100b) according to a
seventh aspect, which may be implemented in conjunction with any
one of the first to sixth aspects, the second coil (102) is
provided separately from the first coil (101).
[0115] This aspect achieves the advantage of reducing the remanent
magnetization of the mover (15) using a simpler configuration
compared to using the first coil (101) as the second coil (102) as
well.
[0116] Note that the constituent elements according to the second
to seventh aspects are not essential constituent elements for the
electromagnetic relay (100) but may be omitted as appropriate.
REFERENCE SIGNS LIST
[0117] 111, 121 Fixed Contact [0118] 21, 22 Moving Contact [0119]
10 Electromagnet Device [0120] 101 First Coil [0121] 102 Second
Coil [0122] 13 Yoke [0123] 15 Mover [0124] 5 Demagnetization
Circuit [0125] 51 Capacitor [0126] 53 Second Switch (Switch) [0127]
54 Control Circuit [0128] AC Power Supply [0129] 100, 100a, 100b,
100c Electromagnetic Relay [0130] .phi.1 Magnetic Flux
* * * * *