Title: Circuit breaker
Abstract: A circuit breaker includes a fixed contact; a movable contact disposed in a rotary-type contact holder; a switching device; an operation handle; and an over-current tripping device. The operation handle is operated to open and close main-circuit contact points through the switching device. The switching device includes a handle lever connected to the operation handle; a toggle linkage having an upper toggle link and a lower toggle link; a switching spring placed between the handle lever and an arm connecting point of the toggle linkage; and a side plate for holding the components. The circuit breaker further includes a device for preventing the operation handle from moving to an off position when the contact points are stuck together. The device includes first stoppers formed on a cross bar of the contact holder and the handle lever facing the cross bar, and a second stopper formed on the side plate.
Patent Number: 6,911,614 Issued on 06/28/2005 to Asano, et al.
| Inventors:
|
Asano; Hisanobu (Saitama, JP);
Mitsushige; Mitsuhiro (Saitama, JP);
Yamagata; Hideto (Saitama, JP);
Takahashi; Yasuhiro (Saitama, JP)
|
| Assignee:
|
Fuji Electric FA Components & Systems Co., Ltd. (Tokyo, JP)
|
| Appl. No.:
|
691673 |
| Filed:
|
October 24, 2003 |
Foreign Application Priority Data
| Oct 28, 2002[JP] | 2002-312629 |
| Current U.S. Class: |
200/401; 200/DIG.42; 335/191; 337/70 |
| Intern'l Class: |
H01H 023/00; H01H003/00; H01H071/10 |
| Field of Search: |
200/400,401,402-472,318-327,DIG.42
335/185,189,191
337/6,7,57-59,70,72
|
References Cited [Referenced By]
U.S. Patent Documents
| 3605051 | Sep., 1971 | Casey et al.
| |
| 3849751 | Nov., 1974 | Link et al.
| |
| 4679016 | Jul., 1987 | Ciarcia et al.
| |
| 5296664 | Mar., 1994 | Crookston et al.
| |
| Foreign Patent Documents |
| 5-182577 | Jul., 1993 | JP.
| |
Primary Examiner: Scott; James R.
Attorney, Agent or Firm: Kanesaka; Manabu
Claims
1. A circuit breaker comprising:
a fixed contact,
a rotatable contact,
a contact holder supporting the rotatable contact,
an operation handle moving between an ON position and an OFF position for opening
and closing the rotatable contact,
an over-current tripping device for performing a tripping operation in response
to an over-current and having a latch,
a switching device including a handle lever connected to the operation handle
and having a support point at an end thereof; a toggle linkage interposed between
the contact holder and the latch and having a connecting pin, and upper and lower
links connected by the connecting pin; a spring disposed between the handle lever
and the connecting pin; and a side plate for supporting the handle lever, the toggle
linkage and the spring, and
means for preventing the operation handle from moving to the OFF position when
the movable contact is stuck to the fixed contact, said means including first stoppers
formed on a cross bar of the contact holder and the handle lever facing the cross
bar, respectively, and a second stopper formed on the side plate of the switching
device for preventing a movement of the operation handle to the OFF position.
2. A circuit breaker according to claim 1, wherein said second stopper is a protrusion
provided on the side plate of the switching device so as to face a rear edge of
the handle lever of the switching device relative to a center of swinging of the
handle lever.
3. A circuit breaker according to claim 1, further comprising a dog formed on
the handle lever and extending toward the toggle linkage and a dog-receiving member
extending from the lower link of the toggle linkage so that when the movable contact
is stuck to the fixed contact and the handle lever is moved from the ON position
to the OFF position, the dog pushes the dog-receiving member to move the connecting
pin of the switching device to a position closer to the ON position of the operation handle.
Description
BACKGROUND OF THE INVENTION AND RELATED ART STATEMENT
The present invention relates to a circuit breaker used for a circuit breaker
of a low-voltage circuit, a ground leakage interrupter, and the like. More specifically,
the present invention relates to a switching device provided in a circuit breaker
and having an isolation function for preventing an operation handle from moving
to an off position when main-circuit contact points are stuck together due to an
abnormal current.
A basic configuration of a circuit breaker to which the present invention is
applied
is shown in FIG.
6. In FIG. 6, reference numeral
1 denotes a case
(resin case) of a circuit breaker; reference numeral
2 denotes a main-circuit
terminal on a power-source side; reference numeral
3 denotes a main-circuit
terminal on a load side; reference numeral
4 denotes a fixed contact; reference
numeral
5 denotes a movable contact; reference numeral
6 denotes
a circuit interrupter; reference numeral
7 denotes a contact holder of the
movable contact
5; reference numeral
8 denotes a switching device;
reference numeral
9 denotes an operation handle; and reference numeral
10
denotes a bimetal-type over-current tripping device.
The switching device
8 has a side plate (assembly frame of the switching
device)
17. The side plate
17 supports a swing-type handle lever
11 connected to the operation handle
9; a toggle linkage
12
having an upper toggle link
12a and a lower toggle link
12b
connected with a connecting pin
12c and bridging the contact
holder
7 of the movable contact
5 and a latch (trip lever)
13
through pin connection; a latch receipt
15 combined with a trip cross bar
14 for locking the latch
13 in a normal state and for releasing the
latch
13 in response to a movement of the over-current tripping device
10;
and a switching spring (tension coil spring)
16 placed between a base (upper
side) of the handle lever
11 and the connecting pin
12c of
the toggle linkage
12.
An operation of switching the circuit breaker is commonly known. When the handle
9 is moved from an "on" position to an "off" position, the switching spring
16 passes over a dead point and is reversed. Accordingly, the upper toggle
link
12a and the lower toggle link
12b of the toggle
linkage
12 are folded into a shape of the symbol "<" with a spring force
of the switching spring
16 to open the movable contact
5.
When an over-current flows during electrification and the over-current tripping
device
10 is activated, the latch
13 is released via the trip cross
bar
14 from a state that the latch
13 engages the latch receipt
15.
As a result, the movable contact
5 is opened by the spring force of the
switching spring
16 to shut down the current (tripping). When the tripping
occurs, the operation handle
9 moves to an intermediate position between
the "on" position and the "off" position together with the handle lever
11
to indicate the tripping. When the circuit breaker is turned on again after the
tripping, the handle
9 is moved to the "off" position, i.e. a reset position,
to engage the latch
13 with the latch receipt
15. Then, the handle
9 is moved back to the "on" position to close the movable contact
5.
In the circuit breaker described above, the fixed contact and the movable contact
may be stuck together when an abnormal current flows through the main circuit in
an electrification state in which the main-circuit contact points are closed. In
this case, even through the over-current tripping device
10 is operated
normally, the movable contact
5 is not opened, and the operation handle
9 remains at the "on" position.
In the switching device described above, it is possible to move the handle
9
from the "on" position to the "off" position by applying a large force thereto,
even when the main-circuit contact points are stuck together. Therefore, when the
contact points are stuck together, an operator can move the handle to the "off"
position and lock the handle with a padlock or the like without knowing the occurrence
of the abnormal event. In this case, the operator may touch a hot line and suffer
an electric shock, if the operator mistakenly confirms that the breaker is turned
off and performs a check and maintenance of the circuit on the load side.
Moreover, the operation handle
9 of the circuit breaker may be provided
with an external operation handle device driven by a motor, so that the operation
handle
9 can be switched through remote control. In this case, when the
operation handle
9 is moved to the "off" position, the external operation
handle device sends a breaker-off signal and locks the operation handle
9
in the "off" position. For this reason, if an abnormal current flows and the contact
points are stuck, the operator mistakenly confirms that the breaker is turned off,
thereby causing a safety issue.
As a countermeasure against such a problem, a configuration is known in which
the circuit breaker is provided with an isolation function for preventing the handle
from moving to the "off" position when the contact points are stuck together during
the electrification. In a specific configuration, the contact holder
7 of
the movable contact
5 and the handle lever
11 are provided with abutting
stoppers having protrusion shapes, respectively. With this configuration, when
the operator intends to move the operation handle
9 to the "off" position
in a state that the contact points are stuck together, the abutting stoppers abut
against each other to prevent the handle from moving to the "off" position (refer
to Japanese Patent Publication (Kokai) No. 05-182577).
A conventional switching device having such a mechanism is shown in FIG.
7.
In FIG. 7, the operation handle
9 is moved to a dead-point position (described
later) from the "on" position, in a state that a contact point
4a of
the fixed contact
4 and a contact point
5a of the movable
contact
5 are stuck together. In the switching device shown in FIG. 7, an
abutting stopper
11a protruding toward the contact holder
7
is formed at an end of the handle lever
11, i.e. a position shifted to the
right side from a rotational center
0 (on the "off" position side of the
operation handle
9). An abutting stopper
7b facing the abutting
stopper
11a is formed on a peripheral surface of the cross bar
7a
of the contact holder
7 (a rotary shaft of the holder).
The handle lever
11 is formed in a branched shape having an upper base
connected to the operation handle
9. A concave groove is formed at an end
of the handle lever for receiving a bearing part
17a having an L-shape
protrusion and formed in an outer surface of the side plate
17, so that
the handle lever
11 is rotatably supported. The switching spring (tension
spring)
16 holds the handle lever
11 at an assembled position. In
general, the handle lever
11 adopts such a support structure in consideration
of ease of assembly of the switching device.
"ON" and "OFF" shown in FIG. 7 denote an "on" position and "off" position of
the operation handle
9 relative to a reference line (an projected line on
the swing fulcrum of the handle lever
11), respectively. Further, "DP" denotes
a dead point at which the operation handle
9 transits from the "on" position
to the "off" position (a state in which the switching spring
16 is in a
neutral position relative to the toggle linkage
12). Furthermore, "SL" denotes
an action line of the spring
16 placed between the connecting pin
12c
of the toggle linkage
12 and an upper side of the handle lever
11.
As shown in FIG. 7, the action line "SL" is on the dead point of the toggle linkage
12 (on a line between the connecting pin
12c of the toggle
linkage
12 and a connecting pin
12d of the latch
13
of the upper toggle link
12a).
In the structure described above, in the state that the contact points are stuck,
when the operator attempts to move the operation handle
9 from the "on"
position to the "off" position, the abutting stopper
11a of the handle
lever
11 abuts against the abutting stopper
7b of the contact
holder
7 situated at the closed position of the contacts at a point that
the operation handle
9 is slightly beyond the dead point DP of the handle,
so that the operation handle
9 is prevented from moving to the "off" position.
In the conventional structure shown in FIG. 7, there are the following problems
concerning an operation of the isolation function.
As shown in FIG. 7, the concave groove formed at the end of the handle lever
11
receives the bearing part
17a formed on the outer surface of the
side plate
17 to rotatably support the handle lever
11. In this structure,
the abutting stopper
11a of the handle lever
11 abuts against
the abutting stopper
7b of the contact holder
7, thereby preventing
the operation handle
9 from moving to the "off" position. In this state,
when the operator intends to further move the operation handle
9 by applying
a large force thereon, the concave groove at the end of the handle lever
11
moves upwardly out of the bearing part
17a. Accordingly, the operation
handle
9 moves to the "off" position around the abutting point of the abutting
stoppers
11a and
7b.
In the configuration described above, when the operation handle
9 moves
to the "off" position, the abutting stoppers
7b,
11a abut
against each other after the action line of the switching spring
16 passes
the dead point DP shown in FIG. 7, so that the abutting stoppers
7b,
11a do not interfere with each other in the normal "on" and "off"
operations. Further, in the state that the contact points are stuck, when the operator
releases the operation handle
9 at a position in which the abutting stoppers
7b,
11a abut against each other to prevent the operation
handle
9 from moving, the operation handle
9 returns to the "on" position.
There may be a case that the "off" position of the operation handle
9
is situated close to the DP position depending on an assembly structure of the
switching device or due to a play between components. In such a case, when the
operation handle
9 is moved toward the "off" position in the state that
the contact points are stuck, the handle
9 may easily return to the "off"
position from the DP position before the handle
9 is securely prevented
from moving.
The operation handle
9 may be locked at the "off" position with a padlock,
or the operation handle
9 may be provided with an external operation handle
device. In such a case, when the operation handle
9 is moved toward the
"off" position in the state that the contact points are stuck, the handle
9
is locked at the "off" position even though the main circuit points are closed,
so that the operator mistakenly confirms that the contact points are opened.
In view of the problems described above, the present invention has been made,
and an object of the invention is to provide a circuit breaker having an improved
configuration relative to the conventional device. In the circuit breaker of the
invention, it is possible to securely prevent the operation handle from moving
to the "off" position even though the contact points are stuck. Also, it is possible
to stabilize the isolation function of the circuit breaker.
Further objects and advantages of the invention will be apparent from the
following description of the invention.
SUMMARY OF THE INVENTION
In order to achieve the objects described above, according to the present invention,
a circuit breaker includes a fixed contact; a movable contact disposed in a rotary-type
contact holder; a switching device; an operation handle; and an over-current tripping
device. The operation handle is operated to open and close main-circuit contact
points through the switching device. The switching device includes a handle lever
connected to the operation handle and having an end portion as a rotational center
thereof; a toggle linkage having an upper toggle link and a lower toggle link and
disposed between the contact holder and a latch of a tripping mechanism; a switching
spring placed between the handle lever and a connecting pin of the toggle linkage;
and a side plate for holding the components. The circuit breaker further includes
means for preventing the operation handle from moving from an "on" position to
an "off" position when the main-circuit contact points are stuck. The means includes
abutting stoppers or first stoppers formed on a cross bar of the contact holder
and the handle lever facing the cross bar, respectively; and a second stopper for
preventing the handle lever from moving around an abutting point of the abutting
stoppers to the "off" position.
According to the present invention, the second stopper is a protrusion
formed on the side plate, and faces an edge surface of a circular arc member formed
on a rear edge of the handle lever around the rotational center of the handle lever.
In the present invention, during a process of moving the operation handle from
the "on" position to the "off" position in a state that the contact points are
stuck, when the handle lever is forced to move to the "off" position with an additional
force from a position where the abutting stoppers abut against each other, the
handle lever abuts against the second stopper and engages the same. Accordingly,
the handle lever does not come out from a bearing part of the side plate around
the abutting point of the abutting stoppers, thereby securely preventing the operation
handle from moving to the "off" position.
According to the present invention, the circuit breaker further includes
a dog extending from a front edge of a base of the handle lever toward the toggle
linkage and a dog-receiving member facing the dog and extending upwardly from the
lower toggle link of the toggle linkage. When the handle lever is moved from the
"on" position to the "off" position, the dog pushes the dog-receiving member of
the lower toggle link so that the dead point of the switching device is shifted
to a position closer to the "on" position of the operation handle. Accordingly,
even in a case in which the "off" position of the operation handle is positioned
close to the DP position of the handle, the circuit breaker can perform the isolation
function stably.
In the present invention, when the operation handle is moved from the "on" position
to the "off" position, the dog of the handle lever abuts against the dog-receiving
member of the lower toggle link of the toggle linkage, and pushes the dog-receiving
member to move a connecting point between the lower toggle link and the upper toggle
link. Accordingly, the toggle linkage is folded into a shape of the symbol "<",
so that the DP position of the toggle linkage relative to an action line of the
switching spring is forcibly moved to a position closer to the "on" position of
the operation handle. When the contact points are stuck, the action line of the
switching spring moves beyond the dead-point position before the operation handle
is moved to a position close to the "off" position, and the abutting stoppers abut
against each other afterward. Therefore, it is possible to securely prevent the
operation handle from moving to the "off" position.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of a switching device of a circuit breaker according
to an embodiment of the invention;
FIG. 2 is a side view showing a portion of the switching device shown in FIG.
1 corresponding to one phase in an "on" state;
FIG. 3 is a side view showing the switching device in an "off" state in a state
that contact points are not stuck;
FIG. 4 is a side view showing the switching device in a state that an operation
handle is moved to the dead-point position during a process of moving from the
"on" position to the "off" position while the contact points are stuck;
FIG. 5 is a side view of the switching device in a state that the operation
handle passes a dead-point position shown in FIG. 4, and abutting stoppers abut
against each other to prevent the operation handle from moving;
FIG. 6 is a sectional view of a basic structure of the circuit breaker; and
FIG. 7 is a side view showing a conventional switching device having an isolation
function in a state that a handle is prevented from moving corresponding to FIG. 4.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
Hereunder, embodiments of the invention will be described with reference
to the accompanying drawings. Note that components in FIGS. 1 to
5 corresponding
to those shown in FIG. 7 are designated with the same reference numerals, respectively,
and descriptions thereof are omitted.
A circuit breaker has a switching device
8 having a basic structure similar
to a conventional circuit breaker shown in FIG.
7. The circuit breaker includes
abutting stoppers or first stoppers
7b,
11a formed
on a contact holder
7 and a handle lever
11, respectively, as means
for preventing an operation handle
9 from moving to an "off" position when
contact points are stuck. In addition to a configuration of the conventional circuit
breaker, the circuit breaker of the invention further includes side plates
17
having second stoppers
17b facing rear edges of the handle lever
11 (toward the "off" position of the operation handle). The second stopper
17b is a protrusion formed on an outer surface of the side plate
17, and faces an edge surface of a circular arc member formed on a rear
edge of the handle lever. The circular arc member has a radius of curvature of
the handle lever
11 relative to a rotational center O.
A dog
11b extends from a front edge of a base of the handle lever
11 toward the toggle linkage, and a dog-receiving member
12b-
1
extends upward from a lower toggle link
12b of a toggle linkage
12
to face the dog
11b.
In the configuration described above, when the contact points are open ("on"
state)
as shown in FIG. 2, an upper toggle link
12a and the lower toggle
link
12b of the toggle linkage
12 are aligned linearly. The
dog-receiving member
12b-
1 extending upward from the lower
toggle link
12b is separated from the dog
11b formed
on the upper base of the handle lever
11. An action line of a switching
spring
16 is located on the left side ("on" position side) relative to a
dead point DP of the toggle linkage
12 (on a line between connecting pins
12c,
12d).
FIG. 3 shows a state in which the operation handle
9 is moved to the
"off" position, and the contact points are opened ("off" state) . In this state,
the toggle linkage
12 is folded into a shape of the symbol "<" , and the
action line of the switching spring
16 is located on the right side ("off"-position
side) relative to the dead point DP. Incidentally, in a normal state in which the
contact points are not stuck together, when the operator moves the operation handle
9 to the "on" or "off" position, the handle lever
11 and the contact
holder
7 are both rotated in the same direction. Accordingly, the abutting
stopper
11a of the handle lever
11 does not abut against the
abutting stopper
7b of the contact holder
7. Further, the
second stopper
17b faces an end face
11c of the circular
arc member of the handle lever
11 around the rotational center O, so that
the stopper
17b does not block the operation handle
9.
An operation of the operation handle
9 from the "on" position to the "off"
position in a state that the contact points are stuck together will be described
next with reference to FIG.
4 and FIG.
5. When the operation handle
9 moves from the "on" position, in a course of the movement, the dog
11b
of the handle lever
11 abuts against the dog-receiving member
12b-
1
extending upward from the lower toggle link
12b of the toggle linkage
12, and pushes the dog-receiving member
12b-
1 to the
right side. As a result, as shown in FIG. 4, the connecting pin
12c between
the lower toggle link
12b and the upper toggle link
12a
moves to the right side. Also, the upper toggle link
12a turns
to a vertical position, and the dead-point position DP of the operation handle
9 moves to a position closer to the "on"-position side (left side of a reference
line of the switching device).
Note that in the conventional structure shown in FIG. 7, the dead-point position
DP of the operation handle is located on the right side of the reference line closer
to the "off"-position side. When the operation handle
9 moves to the position
shown in FIG. 5 beyond the dead point shown in FIG. 4, the abutting stopper
11a
of the handle lever
11 abuts against the abutting stopper
7b
of the contact holder
7, thereby preventing the operation handle
9
from moving.
As described above, in the embodiment of the invention, the dog
11b
and the dog-receiving member
12b-
1 are provided on the
handle lever
11 and the lower toggle link
12b, respectively.
Accordingly, when the operation handle
9 moves from the "on" position to
the "off" position, the connecting pin
12c of the toggle linkage
12 is moved to the right side, and the dead-point position DP is forcibly
changed to a position closer to the "on" position. Therefore, it is possible to
securely obtain an isolation function without an influence of a structure of the
switching device or an assembly variation.
In the conventional structure shown in FIG. 7, when the operator tries to move
the operation handle
9 from the locked state to the "off" position with
a large force, the handle lever
11 rotates clockwise around an abutting
point between the abutting stoppers
11a,
7b (the handle
lever
11 comes out from the bearing part
17a of the side plate
17), and the operation handle
9 moves to the "off" position.
In contrast, in the embodiment of the invention, when the operator tries to move
the handle lever
11 clockwise around the abutting point of the abutting
stoppers, the second stopper
17b abuts against the side edge of the
handle lever
11, thereby preventing the handle lever
11 from moving.
Accordingly, it is possible to securely prevent the operation handle
9 from
moving to the "off" position.
In the embodiment of the invention, the abutting stoppers
11a,
7b
and the second stopper
17b are provided as the means for preventing
the operation handle
9 from moving to the "off" position when the contact
points are stuck together. Further, the dog
11b formed on the handle
lever
11 and the dog-receiving member
12b-
1 extending
from the lower toggle link
12b are provided as the means for shifting
the dead-point position DP to a position closer to the "on" position when the operation
handle
9 is moved from the "on" position to the "off" position. When the
switching device
8 has a structure in which the "off" position of the operation
handle
9 is separated sufficiently from the dead-point position DP, the
dog
11b and the dog-receiving member
12b-
1 can
be omitted.
As described above, the switching device of the invention includes the handle
lever connected to the operation handle and having the end portion as the rotational
center thereof; the toggle linkage having the upper toggle link and the lower toggle
link and disposed between the contact holder and the latch of the tripping mechanism;
the switching spring placed between the handle lever and the arm connecting point
of the toggle linkage; and the side plates for holding the components. The circuit
breaker further includes; first stoppers formed on a cross bar of the contact holder
and the handle lever facing the cross bar; and the second stopper for preventing
the handle lever from moving around the abutting point of the stoppers to the "off"
position as the means for preventing the operation handle from moving to the "off"
position when the main-circuit contact points are stuck.
In the present invention, when the operation handle is moved to the "off" position
while the contact points are stuck, the second stopper prevents the operation handle
from moving to the "off" position around the abutting point of the first stoppers,
thereby increasing the reliability of the isolation function.
Further, in the present invention, when the operation handle is moved from
the "on" position to the "off" position, the dead-point position is forcibly moved
to the position closer to the "on" position, so that the circuit breaker can stably
perform the isolation function without an influence of a structure of the switching
device or an assembly variation.
While the invention has been explained with reference to the specific embodiments
of the invention, the explanation is illustrative and the invention is limited
only by the appended claims.
*
