U.S. patent number 3,800,250 [Application Number 05/284,136] was granted by the patent office on 1974-03-26 for electromagnetic relay.
This patent grant is currently assigned to Matsushita Electric Works, Ltd.. Invention is credited to Tetsuo Mori, Keiji Okahashi, Takeshi Yuda.
United States Patent |
3,800,250 |
Mori , et al. |
March 26, 1974 |
ELECTROMAGNETIC RELAY
Abstract
Electromagnetic relay having a balancing spring for the armature
and engaged between an end of the armature and a stationary part of
the electromagnetic device so that as the armature is attracted
toward the core of electromagnetic device the force of said
balancing spring will be reduced and entire spring load
characteristic will be kept small. This invention relates to
electromagnetic relays. As a balancing spring for a conventional
electromagnetic relay has been used to have a gradient in the
direction of increasing the elasticity of the balancing spring as
the armature is attracted, it has been necessary to increase the
electromagnetic attraction that much and to necessarily enlarge the
electromagnetic device. Therefore, it has been difficult to make
the electromagnetic relay small. According to the present
invention, a balancing spring is used to have a gradient reverse to
that of a conventional one so that the electromagnet may be small
and therefore the problem of making the entire structure of the
electromagnetic relay small may be solved. A main object of the
present invention is to make a magnetic relay small by using a
balancing spring so as to have a gradient reverse to that of a
conventional one. Another object of the present invention is to
simply and cheaply provide an electromagnetic relay wherein the
balancing spring characteristic can be regulated. A further object
of the present invention is to provide an electromagnetic relay
wherein the chattering of contacts is reduced by reducing the
energy of the total spring loads. Another object of the present
invention is to provide an electromagnetic relay which having a
high sensitivity. A further object of the present invention is to
provide a small electromagnetic relay by contriving the shape and
incorporating structure of a balancing spring.
Inventors: |
Mori; Tetsuo (Hirakata,
JA), Yuda; Takeshi (Neyagawa, JA),
Okahashi; Keiji (Neyagawa, JA) |
Assignee: |
Matsushita Electric Works, Ltd.
(Osaka, JA)
|
Family
ID: |
13352566 |
Appl.
No.: |
05/284,136 |
Filed: |
August 28, 1972 |
Foreign Application Priority Data
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|
|
|
|
Sep 1, 1971 [JA] |
|
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46-67703 |
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Current U.S.
Class: |
335/128; 335/192;
335/135; 335/274 |
Current CPC
Class: |
H01H
50/645 (20130101); H01H 50/34 (20130101); H01H
50/641 (20130101); H01H 50/26 (20130101); H01H
50/042 (20130101) |
Current International
Class: |
H01H
50/00 (20060101); H01H 50/64 (20060101); H01H
50/02 (20060101); H01H 50/04 (20060101); H01H
50/26 (20060101); H01H 50/34 (20060101); H01H
50/16 (20060101); H01h 050/00 () |
Field of
Search: |
;335/128,135,192,203,274 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Broome; Harold
Attorney, Agent or Firm: Wolfe, Hubbard, Leydig, Voit &
Osann, Ltd.
Claims
What is claimed is:
1. An electromagnetic relay comprising the combination of:
a. an electromagnetic device including a coil, a core member, and a
pivotally mounted armature,
b. at least one fixed spring contact,
c. a movable contact mounted for making and breaking contact with
said fixed contact in response to pivoting movement of said
armature,
d. and spring means biasing said armature away from said core, said
spring means being responsive to pivotal movement of said armature
for reducing said biasing force on said armature as the armature
moves toward said core, and for increasing said biasing force as
the armature moves away from said core.
2. An electromagnetic relay as set forth in claim 1 wherein said
electromagnetic device comprises an L-shaped yoke to which a core
having an exciting coil is fixed, and an L-shaped armature
rotatably engaged in the end part of said yoke, a part of said
armature being arranged rotatably in a space provided in the side
part of the yoke.
3. An electromagnetic relay according to claim 1 wherein said
spring means is supported on a member of an easily plastically
deformable material and shape.
4. An electromagnetic relay according to claim 3 wherein a part of
said spring supporting member is formed of a metallic frame fixed
to a yoke and has a bridging part in one end part of it and a
projection provided substantially in the center of said bridging
part is made said spring supporting member.
5. An electromagnetic relay according to claim 1 wherein said
spring means is ring-shaped.
6. An electromagnetic relay according to claim 1 wherein said
spring means is of a ring-shape having open ends, engaged at said
open end with a projection provided on said armature and rotatably
engaged on the side opposite the open ends with the receiving part
provided to project on the upper part of the supporting frame.
7. An electromagnetic relay according to claim 1 wherein said
spring means is of a ring-shape having open ends and engaged in
both open end parts with two projections provided on the armature
and also on the side opposite the open ends with a spring
supporting member.
8. An electromagnetic relay as set forth in claim 1 wherein the
combined spring characteristics of said spring contact and said
spring means provide a spring load on said armature which varies in
proportion to the electromagnetic force on said armature as the
armature moves toward said core.
9. An electromagnetic relay as set forth in claim 1 which includes
a pair of fixed spring contacts disposed on opposite sides of said
movable contact.
Description
The present invention shall be explained in the following with
reference to the drawings, in which:
FIG. 1 is a sectional view of an electromagnetic relay of the
present invention;
FIG. 2 is a disassembled perspective view;
FIG. 3 is a perspective view with the case, contact spring
assembly, base and card removed;
FIG. 4 is an explanatory view showing a balancing spring as
engaged;
FIG. 5 is a characteristic view of the spring system;
FIG. 6 is a perspective view showing the shape of a balancing
spring;
FIG. 7 is an explanatory view of the balancing spring as the
engaging position is varied.
In FIG. 1 showing a sectioned view of a relay of the present
invention, 1 is a yoke, 2 is an iron core fixed to the above
mentioned yoke, 3 is a coil bobbin arranged around the core 2, 4,
is a coil wound on the above mentioned coil bobbin, 5 is a base
made of an insulator, 6 is a coil terminal inserted into the above
mentioned base 5,7 is a lead wire and 8 is an L-shaped balancing
spring supporting frame fixed to the base 5 with a fitting
screw.
9 IS AN L-shaped armature engaged in the extention 10 rotatably
with the lower end of the yoke 1 (See FIG. 2). 11 is a balancing
spring engaged between a projection 12 provided on the armature 9
and a spring receiving part 13 provided on the upper part of the
supporting frame 8. Said spring receiving part 13 on the supporting
frame 8 is provided on the bridging part at the free of the
supporting frame 8 so that the biasing force of the above mentioned
balancing spring 11 may be adjusted by plastically deforming the
bridging part. 14 is a stationary contact. 15 is a stationary
contact spring. 16 is a stationary contact spring block molded
integrally with the lower part of the stationary contact spring. 17
is a first moving contact. 18 is a first moving contact spring. 19
is a terminal. 20 is a first moving spring block made of an
insulator. 21 is a second moving contact. 22 is a second moving
contact spring. 23 is a terminal. 24 is a second moving spring
block. 25 is a terminal of the stationary contact. 26 is a contact
spring assembly frame made of an insulator. The first and second
moving spring blocks 20 and 24 and stationary contact spring block
16 are pressed into a space in the center of said assembly frame 26
and are fixed to the base 5 with the supporting frame 8. 27 is a
card fixed to the upper part of the armature 9 so that the moving
springs 18 and 22 may be moved on both sides of a spacer part 28
provided on a driving piece. 29 is a case.
In FIG. 2 showing a disassembled perspective view, the fitting
relations are indicated with the arrows. What must be particularly
explained here is the fitting state of the armature 9. A notch
provided in the extension 10 of the armature 9 is loosely fitted
with a projection 30 provided on the lower part of the yoke 1 so
that the armature 9 may be rotated by the excitation of the coil 4
at this pivoting point. Further, a projection 31 of the yoke 1 is
fitted in a hole 32 made on the side wall of the balancing spring
supporting frame 8 and a projection 33 of the yoke 1 is fitted in a
hole 34 made on each side wall of the supporting frame 8 and is
secured to the frame 8 which is fixed to the base 5 with a screw.
The balancing spring 11 is ring-shaped and is rotatably engaged at
the open end with a projection 12 provided on the armature 9 and
also rotatably engaged on the side opposite the open ends with a
receiving part 13 on the supporting frame 8.
FIG. 3 is a perspective view showing the balancing spring 11 as
engaged. The tail part 36 of the armature 9 is rotatably arranged
in a space 35 provided in the side part of the yoke 1. The spring
11 is, further, arranged in parallel to side surface of the yoke
1.
The operation of the electromagnetic relay of the present invention
shall be explained in the following.
FIG. 4A shows a view in which the resiliency of the balancing
spring is decomposed into a component F.sub.3 vertical to the yoke
and a component parallel with the yoke.
FIG. 4B shows a spring force of the balancing spring in the initial
state in which the coil is not excited. In the drawing, a is a
rotating center of the armature, b is a rotating center of the
balancing spring and c.sub.1 is a point of rotation with a radius
of i.sub.2 with the point a as a center. l.sub.1 is a distance from
the point a to the center of the core and L is a distance between
the armature and core in the center position of the core. Further,
the angle formed by a line connecting a and c.sub.1 and a line
connecting b and c.sub.1 is .theta..sub.1.
If the spring force given to the point c of the balancing spring is
F.sub.1 ', the direction of the force line of F.sub.1 ' will be on
the line bc.
If the component in the tangential direction at the point C of
F.sub.1 ' is T.sub.1 ' and the component in the normal direction is
P.sub.1 ',
T.sub.1 '= f.sub.1 'sin.theta..sub.1 and
P.sub.1 '=f.sub.1 ' cos.theta..sub.1 .
Here, T.sub.1 ' will be a torque tending to separate the armature
from the core and P.sub.1 ' will be a force pressing the armature
to the yoke hinge part.
If the force in the core position of T.sub.1 ' is T.sub.1,
T.sub.1 l.sub.1 = T.sub.1 'l.sub.2
That is, T.sub.1 = (l.sub.2 /l.sub.1)T.sub.1 ' = (l.sub.2
/l.sub.1)F.sub.1 'sin.theta..sub.1 .
FIG. 4C shows a spring force of the balancing spring in the final
state in which the coil is excited and the attraction of the
armature is finished. In this case,
T.sub.2 = (l.sub.2 /l.sub.1)F.sub.2 'sin.theta..sub.2 .
Therefore, the smaller the distance of the armature from the core,
the smaller the angle .theta..
If various amounts are set so that F.sub.2 ' - F.sub.1 ' <
sin.theta..sub.1 - sin.theta..sub.2, there will be obtained a
negative characteristic that, the smaller the distance between the
core and armature, the smaller the force tending to separate the
armature from the core.
In FIG. 5, the abscissa represents the clearance between the
armature and core, L represents the case that the armature and core
separate from each other most and L = O represents the case that
the armature has attracted the core. As the excited core attracts
the armature, L will reduce gradually and the card 28 will move in
the direction indicated by the arrow X (in FIG. 4). The load
characteristic F.sub.2 of the second contact spring 22 shows that,
at L = a, the right end of the card 28 contacts the second contact
spring 22 and that, at L = b, the fixed contact 14 and second
moving contact 21 tend to separate from each other. The load
characteristic F.sub.2 of the first contact spring 18 shows that,
at L = c, the fixed contact 14 and first moving contact 17 contact
each other and that, at L = d, the left end of the card 28 tends to
separate from the first contact spring 18.
In the drawing, F.sub.2 is a spring load characteristic by the
first contact spring 18, F.sub.1 is a spring load characteristic by
the second contact spring 22, F is a sum of the first contact
spring load characteristic F.sub.2, and second contact spring load
characteristic F.sub.1, that is,
F = f.sub.1 + f.sub.2 ,
f.sub.3 .sup.- is a characteristic of the balancing spring having a
negative characteristic (that, the smaller the clearance between
the core surface and armature, the smaller the force) (the case of
the conventional example), F.sup.- is a combined spring
characteristic, that is, F.sup.- = F.sub.1 + F.sub.2 + F.sub.3
.sup.- (the case of the present invention), F.sub.3 .sup.+ is a
characteristic of the balancing spring having a positive
characteristic (that, the smaller the clearance between the core
surface and armature, the larger the force) (the case of the
conventional example) and F.sup.+ is a combined spring
characteristic, that is,
F.sup.+ = f.sub.1 + f.sub.2 + f.sub.3.sup.+
(the case of the conventional example).
As evident from the drawing, F.sup.- < F.sup.+. Therefore, for
the electromagnetic attraction, there are required f.sup.+ for
F.sup.+ and f.sup.- for F.sup.-. Therefore, f.sup.-< f.sup.+.
According to the present invention, the electromagnetic attraction
is so small that it is possible to make the electromagnetic relay
small and to increase the sensitivity.
FIG. 6 shows the shape of the balancing spring. By the way, though
this balancing spring has open ends, such open ends are not always
necessary and the spring may be ring-shaped.
In this balancing spring, by applying a plastic deformation to the
bridging part of the supporting frame receiving part, the balancing
spring supporting state can be varied and the direction and
magnitude of the spring force can be easily varied.
This example is shown in FIGS. 7A to 7F. In the drawings, c.sub.1
is an engaging point of the balancing spring with the supporting
part 12 before the armature is attracted, c.sub.2 is an engaging
point of the balancing spring with the supporting part 12 after the
armature is attracted, a is a pivoting point of the armature with
the yoke and b is a engaging point of the balancing spring with the
spring receiving part 13 on the supporting frame.
FIGS. 7A to 7D show examples in which the balancing spring
supporting point b is varied.
FIG. 7E shows the results.
FIG. 7A shows an initial position before the supporting point is
adjusted.
FIG. 7B shows the case that the point b is moved toward the point
a.
FIG. 7C shows the case that the point b is moved onto ac.sub.2.
FIG. 7D shows the case that the point b is moved leftward from
ac.sub.2.
FIG. 7F shows a combined spring load characteristic in case the
balancing spring is supported in the state of FIG. 7D.
Depending on the manner of taking the position of the balancing
spring supporting point b, during the travel of the armature, the
direction of the spring force may change. This manner is shown as
F.sub.3 '.sup.- in the drawing. The spring load characteristic will
be F'.sup.- , which will be a force generally smaller than F.sup.-
shown in FIG. 5 and will never be a bar to the charactistic.
However, as the position in which the direction of the force
changes, that is, the point L' is positioned at a point closer to
the point L, the points a, b and c will become smaller forces and,
in the extreme case, the forces of the points b and c will become
negative (the forces of the points a, b and c must be positive),
therefore the force of the point l will have to be made large and
the force of the point d will happen to be large. As explained also
in FIG. 9, this is very disadvantageous to the characteristic of
the electromagnetic attraction.
Further, when the force of the point a is smaller than is required,
the returning operation of the electromagnetic relay will be hard
to make and, in the extreme case, the electromagnetic relay will
not return well.
From the above, it is found that the point L' may be present
between O and L (that is, the direction of the force may change)
but must in a position close to the point O.
As described above, the present invention has the following
effects:
a. As the armature is attracted by the core, the balancing spring
will be engaged so that the spring force may reduce. Therefore, the
combined spring characteristic can be reduced so much that the
attraction for the armature can be small, the electromagnetic relay
can be made small, the spring load can be kept low and therefore a
high sensitivity electromagnetic relay can be realized. Further, as
additional effects, the energy of the spring load will reduce and
therefore the chattering of the contacts will decrease.
b. By making the balancing spring ring-shaped, the direction of the
spring displacement can be made effective and the relay can be made
small.
c. By plastically deforming the balancing spring receiving part,
the balancing spring supporting point can be varied and the spring
characteristic can be freely regulated.
* * * * *