Electromagnetic relay

Details Electromagnetic relay Electromagnetic relay

2001-09-24

2003-07-08

Enad, Elvin (Department: 2832)

Electricity: magnetically operated switches, magnets, and electr

Electromagnetically actuated switches

Polarity-responsive

C335S080000, C335S083000, C335S202000

Reexamination Certificate

active

06590480

ABSTRACT:

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS
Japan Priority Application 2000-291890, filed Sep. 26, 2000 including the specification, drawings, claims and abstract, is incorporated herein by reference in its entirety.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an electromagnetic relay comprising a case with an opening at one end thereof, which covers the whole relay, a spool with a coil as an electromagnet wound therearound, a fixed contact, and a movable contact, wherein a first flange of the spool is located on the opening of the case, a second flange of the spool is located on an inner side of the case, the fixed contact and the movable contact are oppositely disposed at positions closer to the inner part than the second flange of the spool, and a fixed terminal with the fixed contact provided thereon is mounted on the spool.
2. Description of the Related Art
Generally, an electromagnetic relay is constructed such that a movable contact and a fixed contact are located on an opposite side (case inner side) of a terminal side from which connection terminal ends of terminals are derived. The movable contact is moved in an axial direction of the coil to cause a switchover of a conduction state (contact state) to the fixed contact. In such an electromagnetic relay, as described also in Japanese Patent Unexamined Publication No. Sho. 56-93234, it is a common practice that the fixed terminal with the fixed contact secured at one end thereof is secured, by press-fitting or the like, to a thick part of the case-inner-side flange of the resin spool on which a coil is to be wound. Another type of electromagnetic relay is also known. In the electromagnetic relay, the other end (connection terminal end) of the fixed terminal is press fit to a base located outside the terminal-side flange of the spool, whereby the fixed terminal is firmly supported (see FIG. 2 of Japanese Utility Model Unexamined Publication No. Hei. 3-12198).
Size and cost reduction is a strong demand in the small electromagnetic relay (height: 20 mm or less), which is mounted on a printed circuit board used in a motor vehicle. To meet the demand, further reduction of the number of required component parts and further increase of parts assembling density are essential.
An electromagnetic relay presenting a solution to such a problem is disclosed in Japanese Patent Unexamined Publication No. Hei. 10-162712. In the publication, a member called a base, which is conventionally used as the base in assembling the relay parts, is omitted. One of the flanges of the spool, on which a coil for the electromagnet is to be wound, is located inside the opening of the case, and this flange is used for the base.
In this type of small electromagnetic relay, a sealed electromagnetic relay (i.e., sealing type relay) is dominantly used in order to endure the washing process carried out after it is mounted on the printed circuit board, and to secure given water- and dust-proof performance. The washing process is carried out after the soldering for mounting the relay on the printed circuit board. Accordingly, the relay being heated is rapidly cooled by the washing liquid. This gives rise to a pressure difference between the inside and the outside of the relay. In this condition, washing liquid is easily pulled into the relay assembly through gap or gaps even if gap or gaps are small. To avoid this, a high degree of hermeticity is required for the relay assembly.
FIG. 8A
shows a diagram of a conventional electromagnetic relay of such a type for the purpose of comparison.
In this relay designated by reference numeral
1
, a flange
2
a
located on the case opened side of a spool
2
is used as a base in assembling the electromagnetic relay. The relay
1
is constructed with the spool
2
, an iron core (not shown) of the electromagnet mounted while being inserted into the spool
2
, an L-shaped yoke
4
, a movable iron member
5
, an L-shaped movable contact spring (movable contact terminal)
6
, a movable contact
7
, a first fixed contact (NC contact)
8
, a first fixed terminal
9
, a second fixed contact (NO contact)
10
, a second fixed terminal
11
, first and second coil terminals
12
and
13
, and a case
14
. A coil
1
a
forming an electromagnet is wound around the spool
2
. The yoke
4
is coupled to the iron core, and provides a magnetic path allowing lines of magnetic force to pass therethrough. The movable iron member
5
is joined at the base end to the top end (=the upper end in
FIGS. 8A and 8B
) of the yoke
4
, and the top end of the movable iron member
5
may be swung under attraction by the iron core when current is fed to the coil. The movable contact spring
6
consists of a plate spring the top end of which may be swung, and mounted on the movable iron member
5
at the top end thereof. The movable contact
7
is mounted to the top end of the movable contact spring
6
. The movable contact
7
is in pressing contact with the first fixed contact
8
when no current is fed to the coil. The first fixed contact
8
is mounted on the upper end of the first fixed terminal
9
. The movable contact
7
is in pressing contact with the second fixed contact
10
when current is fed to the coil. The second fixed contact
10
is mounted on the upper end of the second fixed terminal
11
. The first and second coil terminals
12
and
13
are connected to lead wires of the coil, respectively. An assembling side (=lower side in
FIGS. 8A and 8B
) of the case
14
is opened.
The strip-like parts of the movable contact spring
6
, first fixed terminal
9
and second fixed terminal
11
, which are extended to the opened side (=lower end side in
FIGS. 8A and 8B
) of the case
14
, are protruded to positions outside the flange
2
a
(base) to form connection terminals
21
to
23
used for connecting the individual contacts to given circuit conductors, respectively, like the first and second coil terminals
12
and
13
. In
FIGS. 8A and 8B
, the second coil terminal
13
is located on the opposite side of the first coil terminal
12
. The lower end of the first fixed terminal
9
(=connection terminal
22
) is also located on the opposite side of the lower end of the second fixed terminal
11
(=connection terminal
23
).
In assembling the relay
1
, components parts other than the case
14
are assembled, while using the flange
2
a
as the base member, into a sub-assembly. The case
14
is applied to the sub-assembly to cover the latter. Thereafter, the opening side of the case
14
is sealed with a sealing material
20
, e.g., thermosetting resin, to complete an electromagnetic relay.
The first fixed terminal
9
and the second fixed terminal
11
are press-fit to the flange
2
a
(case-opened-side flange) of the spool
2
at positions indicated as A in FIG.
8
A. Those fixed terminals are also press-fit to a flange
2
b
(case-inner-side flange) of the spool
2
at positions denoted as B in FIG.
8
A.
In the relay of the above-mentioned type, there are the following problems.
(1) As described above, the fixed terminals with the fixed contacts secured thereto are secured to the case-inner-side flange, or to both the case-inner-side flange and the case-opening-side flange as shown in FIG.
8
A. Therefore, there is a chance that in an abnormal state of overcurrent feeding, the second fixed contact (NO contact)
10
is left in contact with the movable contact
7
(their conduction state is retained).
The reason for this is that in a state where overcurrent is fed to the coil, the coil
1
a
is heated to high temperature, and hence it is thermally expanded in the axial direction of the coil. As a result, the spool
2
is deformed such that the flanges
2
a
and
2
b
are spaced apart from each other as indicated by arrows in FIG.
8
A. With the deformation, a part of the second fixed terminal
11
near its position at which the fixed terminal is secured to the flange
2
b
located at the inner side of the case (i.e., part to which the second fixed contact

Affiliated with

Also associated with

Rating

Electromagnetic relay does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Electromagnetic relay, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Electromagnetic relay will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3038523