U.S. patent number 3,774,129 [Application Number 05/305,078] was granted by the patent office on 1973-11-20 for no-fuse circuit breaker.
This patent grant is currently assigned to Tokyo Shibaura Electric Company. Invention is credited to Sigeru Sugiyama.
United States Patent |
3,774,129 |
Sugiyama |
November 20, 1973 |
NO-FUSE CIRCUIT BREAKER
Abstract
A no-fuse circuit breaker comprising at least one movable
contact arm, one end portion of which is rotatably supported on a
mechanism frame and the other end of which is provided with a
contact point engagable with a stationary contact in the mechanism.
An intermediate portion of the movable contact arm is operatively
connected to one end of a pair of links operatively connected in
series, the other end of the links being operatively connected to
an operating handle rotatably mounted on the mechanism frame. A
latching member is rotatably mounted on the mechanism frame, being
engageable with one end of a releasable member, the other end of
the releasable member being operatively connected to a knee
connection between the pair of links, whereby the movement of the
knee connection is restricted by the releasable member when latched
by the latching member. Thus, the movable contact arm is actuated
by the operating handle when the releasable member is latched by
the latching member, and the movable contact arm can be tripped
when the restriction in the movement of the knee connection of the
links is released due to disengagement of the releasable member
with the latching member as may be caused by the rotation
thereof.
Inventors: |
Sugiyama; Sigeru (Machida-shi,
Tokyo, JA) |
Assignee: |
Tokyo Shibaura Electric Company
(Kawasaki-shi, JA)
|
Family
ID: |
14581296 |
Appl.
No.: |
05/305,078 |
Filed: |
November 9, 1972 |
Foreign Application Priority Data
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|
|
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Dec 1, 1971 [JA] |
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46/112222 |
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Current U.S.
Class: |
335/167; 335/175;
335/172; 335/191 |
Current CPC
Class: |
H01H
71/528 (20130101) |
Current International
Class: |
H01H
71/52 (20060101); H01H 71/10 (20060101); H01h
009/20 () |
Field of
Search: |
;335/174,175,35,38,221,167,168,169,170,191,21,172 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Broome; Harold
Claims
What is claimed as new and desired to be secured by Letters Patent
of the United States is:
1. A no-fuse circuit breaker comprising:
an insulative casing;
a mechanism frame mounted in said casing at one side thereof and
having a pair of side plates arranged in parallel relation, each of
said side plates having an elongated slot therein;
a stationary contact member mounted on the other side of said
casing at the bottom thereof;
a movable contact arm supported at one end thereof by and between
said side plates, having a contact portion at the other end thereof
engageable with said stationary contact member and being spring
biased to normally separate said contact portion thereof from said
stationary contact member;
an operating handle rotatably supported by and between said side
plates and having one portion extending outwardly from said
casing;
an upper link rotatably connected at one end portion thereof to
said operating handle at another portion;
a lower link operatively connected at one end portion thereof to
the other end portion of said upper link, the other end portion of
said lower link being rotatably connected to an intermediate
portion of said movable contact arm;
a releasable member operatively connected at one end portion
thereof to the connection between said upper and lower links, and
being slidably guided at its other end portion by said slots in
said side plates;
a latching member rotatably mounted on and between said side
plates, being capable of latching said other end portion of said
releasable member, and being spring biased to be resiliently kept
in position engageable with said other end portion of said
releasable member; and
means for actuating said latching member to disengage from said
releasable member in response to a flow of current larger than a
predetermined value;
whereby said movable contact arm may be actuated to open and close
said movable contact portion thereof and said stationary contact by
said operating handle when said releasable member is latched by
said latching member, and said movable contact arm can be tripped
when the engagement of said releasable member with said latching
member is released by the operation of said actuating means.
2. A no-fuse circuit breaker as claimed in claim 1, where
said releasable member is a substantially U-shaped rod, one leg
portion thereof being adapted to function as a connecting pin for
said upper and lower links and the other leg portion thereof being
inserted through said slots in said side plates.
3. A no-fuse circuit breaker as claimed in claim 1, wherein
said means for actuating said latching member is an electromagnetic
trip arrangement.
Description
BACKGROUND OF THE INVENTION
1. Field of The Invention
This invention relates generally to a no-fuse circuit breaker of a
relatively small rated overload current.
2. Description Of The Prior Art
Many kinds of mechanisms for use as relatively small no-fuse
circuit breakers have heretofore been developed, but these
mechanisms that are adapted for use in combination with an
electromagnetic trip arrangement, while being generally successful,
have had such disadvantages that they have not been found to be
entirely satisfactory. For example, these mechanisms have been
relatively complicated and therefore difficult to adjust, and in
addition, a high degree of manufacturing accuracy has thus been
required.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a
no-fuse circuit breaker of relatively small size and of simple
construction.
Another object of this invention is to provide a no-fuse circuit
breaker which is capable of being tripped by a relatively small
force.
Still another object of this invention is to provide an improved
no-fuse circuit breaker, which is adapted for use in combination
with an electro-magnetic trip arrangement.
Briefly stated, the foregoing objects and others are achieved
according to one aspect of this invention through the provision of
a circuit breaker having a movable contact arm rotatably supported
about one end in a mechanism frame and having a contact member on
its other end engage-able with a stationary contact member mounted
in the mechanism frame, an operating handle rotatably supported in
said mechanism frame and operatively connected through a pair of
serially connected links to an intermediate portion of the movable
contact arm, a releasable member formed in a U-shaped configuration
having one leg rotatively conneted through the axis of the knee
connection of the links and the other slidably guided in arcuate
slots in the mechanism frame, and a latching member rotatably
mounted in the frame capable of latching the other end of the
releasable member and resiliently biased to be kept in engagement
therewith. An electromagnetic trip arrangement is provided for
actuating the latching member to disengage it from the releasable
member responsive to a current larger than a predetermined value in
the circuit.
BRIEF DESCRIPTION OF THE DRAWINGS
Various other objects, features and attendant advantages of the
present invention will be more fully appreciated as the same
becomes better understood from the following detailed description
when considered in conjunction with the accompanying drawings
wherein like reference numerals designate like or corresponding
parts throughout the several views, and in which:
FIG. 1 is a schematical side view, shown partially in
cross-section, of a preferred embodiment of the present invention,
the mechanism being shown in the circuit open state;
FIG. 2 is a schematical side view, with parts omitted, of the
necessary portion of the embodiment shown in FIG. 1 for
illustrating the operation thereof, the mechanism being shown in
the circuit closed state;
FIG. 3 is a view similar to that shown in FIG. 2 wherein the
mechanism is shown in the open state just after having been
tripped;
FIG. 4 is a perspective view of important portions in the
embodiment shown in FIG. 1; and
FIG. 5 is a perspective view, partially broken away and with some
parts omitted of a "three-pole" no-fuse circuit breaker according
to the mechanism of the embodiment shown in FIG. 1.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT
Referring now to the drawings, and particularly to FIG. 1 thereof,
a no-fuse circuit breaker is shown having a casing which comprises
a base 11 and a cover 12 of insulating material.
A line terminal 13 is provided in the base 11 at one end thereof
having an extension 14 carrying a stationary contact 15. On the
other end of the base 11 there is provided a load terminal 16
electrically connected to a coil 17, to be described, which in turn
is electrically connected to a movable contact arm 18 through a
flexible conductor 19.
There is provided a mechanism frame 20 comprising a pair of side
plate members 21 and 22 and L-shaped yoke member 23, all of these
members being made of metal. The side plates 21 and 22 are
symmetrical in construction and disposed in parallel planes, as
shown in FIG. 4, and are secured to the yoke member 23 by suitable
means, such as by a force fit. (In FIG. 1 the side plate 22 is not
seen, and in FIGS. 2 and 3 the side plate 21 is omitted.) Arcuate
slots 211 and 221 are provided in the side plates 21 and 22,
respectively, as shown in FIG. 4.
Rotatably mounted on the top of the frame 20 by a pin 24 is an
operating handle 25, of conventional design being made of
insulating material, which is operatively connected to a link 26 by
a pin 27. The handle 25 is spring biased in the counter clockwise
direction, as viewed in the drawings, by a pair of spring 28
provided around the pin 24 and outside the lower extension of the
handle 25 between the side plates 21 and 22, as shown in FIG. 1,
only the one spring of the side viewed in the drawing being
shown.
The movable contact arm 18 has an integral projected portion 181 at
one end for functioning as a stop and an egg-shaped hole 182 having
a pin 29 inserted therein for supporting the arm 18 on the frame
20. The movable contact arm 18 is provided also with a contact 30
at its other end, being engageable with the stationary contact 15.
The idle clearance between the hole 182 and the pin 29, by
incorporating a spring 31, permits contact pressure to be provided
between the movable and stationary contacts 30 and 15. The spring
31 gives a biasing force in the counter-clockwise direction, as
viewed in the drawings, and is of the shape shown in FIG. 4. The
intermediate portion of the movable contact arm 18 is operatively
connected by an insulated pin 32 to a lower link 33 which is
rotatably connected, at the top end portion thereof, to the bottom
end portion of the upper link 26 to form a knee connection.
A releasable member 34 is provided, a lower end thereof being
connected to the knee connection between the upper and lower links
26 and 33. An upper end of the member 34 is slidable in the slots
211 and 221, and is adapted to be latched. Thus, the movement of
the knee connecting axis is restricted by the releasable member
when the same is latched. In detail, the releasable member 34 is a
U-shaped rod as shown in FIG. 4, one leg portion 341 thereof acting
as a connecting pin for links 26 and 33, and the other leg portion
342 being inserted through the slots 211 and 221 of the side plates
21 and 22 so as to be slidably guided by the slots 211 and 221.
Latching of the releasable member 34 is provided by a latching
member 35 rotatably mounted on the mechanism frame 20 by a pin 36.
The member 35 has tooth portions 351 and 352 capable of latching
the upper leg portion 342 of the releasable member 34, and has arms
353 and 354 to support an actuating rod 37 of insulating material,
as clearly shown in FIG. 4. The latching member 35 is also spring
biased in the clockwise direction, as viewed in the drawings, by a
spring 38 provided around the pin 36 between the arms 353 and 354.
An operation to move the rod 37 righward, as seen in FIG. 4, will
cause the releasable member 34 to be released from its engagement
with the latching member 35.
In order to actuate the rod 37 in the rightward direction when a
current larger than a predetermined value flows from the line
terminal 13 to the load terminal 16, the coil 17, already
mentioned, is arranged in series with the current path between the
line and load terminals 13 and 16. Mounted in the axial bore of the
coil 17 is a core member 39 of soft ferro-magnetic material, such
as soft iron, which is fixed to the yoke member 23 and has a pole
portion 391 at the top end thereof. Facing the pole portion is an
armature member 40, also of soft ferro-magnetic material, such as
soft iron, which is rotatably mounted on the mechanism frame 20 by
the pin 36 together with the latching member 35, but independently
therefrom. As clearly shown in FIG. 4, the armature 40 has a pair
of extensions 401 and 402, each having a lower portion bent in a
substantially U-shaped configuration the base of which can abut on
the rod 37 to move the same to the right when the armature 40
rotates about the pin 36 in the counter-clockwise direction. The
armature 40 is also spring biased in the clockwise direction by a
compression spring 411 provided between a tab 403 of the armature
40 and a tab 231 of the yoke member 23.
A suitable arc extinguishing structure 41 of conventional design is
provided in the base 11. The reference numeral 42 designates a
projection of elongated cube-like shape integrally provided on the
inner wall of the cover 12 for limiting the upward movement of the
mechanism frame 20.
In operation, in order to close the circuit breaker from the open
state shown in FIG. 1, the operating handle 25 must be moved from
the "OFF" position to the "ON" position. In the "OFF" position,
which also means the "RESET" position, the latched leg portion 342
of the releasable member 34 is engaged with the tooth portions 351
and 352 of the latching member 35, so that the releasable member 34
is latched by the latching member 35, whereby the knee connection
of the links 26 and 33 can be moved only along the circular locus
as indicated by the reference character A in FIG. 1. Accordingly,
the operating handle 25 is operated to rotate in the clockwise
direction, against the biasing force of the springs 28 and 31,
whereupon the movable contact arm 18 rotates substantially around
the pin 29 in the clockwise direction to contact the movable
contact 30 with the stationary contact 15. In accordance with that
movement, the intermediate portion of the contact arm 18 is then
moved further downward by the link 33, and the contact arm 18 is
rotated in the counter-clockwise direction substantially around the
contact point of the contacts 15 and 30 because of the presence of
the clearance 182 about the pin 29. Thus, the biasing force of the
spring 31 functions to provide suitable contact pressure between
the movable and stationary contacts 30 and 15. When the pin 27
passes substantially over an imaginary line defined by connecting
the pin 24 and the knee connection axis of the links 26 and 33, the
upward force in the link 33 caused by the spring 31 urges the
handle 25 to rotate in the clockwise direction against the biasing
force of the springs 28, but such clockwise rotation of the handle
25 is now limited by the collision of the pin 27 with side plates
21 and 22, as shown in FIG. 2. Hence the mechanism holds the closed
state of the circuit. In this connection, the latched leg 342 of
the releasable member 34 will move to the right because it is
slidably guided by the slots 211 and 221 as well as being pulled by
the links 26 and 33, but the leg 342 still remains latched by the
latching member 35.
Manual opening of the circuit is performed by rotating the handle
25 in the counter-clockwise direction. The movements of each of the
parts are similar, but in reverse relation, so that the detailed
explanation thereof may be omitted.
Next the trip operation which occurs when a current above a
predetermined value flows in the circuit will be described.
In the closed state of the circuit, as shown in FIG. 2, the
armature 40 is pulled down to contact the pole 391 of the core 39
when the flow of current in the coil 17 becomes larger than a
predetermined value. The movement of the extensions 401 and 402 of
the armature 40 pushes the insulator rod 37 supported by the arms
353 and 354 of the latching member 35 to the right so that the
latching member 35 rotates in the counter-clockwise direction to
release the latched leg 342 of the releasable member 34.
Accordingly, the upper leg 342 of the releasable member 34, which
was latched until this time, as shown in FIG. 2, becomes movable
rightwardly and moves rightward along the slots 211 and 221 of the
side plates 21 and 22, because the member 34 is pulled by the links
26 and 33. In other words, restriction in the movement of the knee
connection axis of the links 26 and 33 is now removed, and the
movable contact 30 becomes separated from the stationary contact
15, as shown in FIG. 3.
Slightly after this, or substantially at the same time, the
operating handle 25 is caused to rotate in the counter-clockwise
direction by the springs 28. In response to this, the link 26,
first moves downwardly and clockwisely, and then moves upwardly and
clockwisely, with result that the upper leg 342 of the releasable
member 34 moves leftwardly along the slots 211 and 221 to be
re-engaged by the latching member 35. Thus, when an overlaod
current flows, the mechanism is automatically tripped and reset, as
shown in FIG. 1.
As understood from the above description, by a relatively small
force, the latching member can be actuated to release the upper
latched leg 342 of the releasable member 34, because the upper
latched leg 342 is slidably guided by means of the slots 211 and
221 in the side plates 21 and 22, and the mechanism can be composed
of a relatively small number of parts which, in addition, have
relatively simple shape. This in turn means that a mechanism of
stabilized characteristics and of good performance can be provided
which is low in cost and takes little space.
It is noted that this invention is also applicable to a polyphase
circuit breaker such as a "three-pole" circuit breaker, although
the description hereinabove refers to only a "single-pole" circuit
breaker.
In FIG. 5 which shows a perspective view of the three-pole no-fuse
circuit breaker according to this invention, the central pole has
substantially the same construction except that the rod 37 mounted
on the latching member 35 and the rod 32 for actuating the movable
contact arm 18 extend axially beyond both ends from that shown in
FIGS. 1-4. Each of the two outside mechanisms has no handle 25 of
their own, nor the upper and lower links 26 and 33, the releasable
member 34, and the latching member 35. The respective movable
contact arms 18 in the two outside mechanisms are connected to the
actuating rod 32 of the central mechanism, whereby all of the
movable contact arms 18 are operated simultaneously, and the
latching member 35 provided only in the central mechanism can be
moved by operation of at least one of the armatures 40 provided on
the respective poles. Thus, all of the movable contact arms 18 can
be operated manually by the handle 25, and all of the circuits can
be tripped when an overload current flows in any one of the
poles.
Obviously many modifications and variations of the present
invention are possible in light of these teachings. It is therefore
to be understood that within the scope of the appended claims, the
invention may be practiced otherwise than as specifically described
herein.
* * * * *