Electricity: electrical systems and devices – Housing or mounting assemblies with diverse electrical...
Reexamination Certificate
2002-11-25
2003-08-12
Tso, Edward H. (Department: 2838)
Electricity: electrical systems and devices
Housing or mounting assemblies with diverse electrical...
Reexamination Certificate
active
06606239
ABSTRACT:
BACKGROUND OF THE INVENTION AND RELATED ART STATEMENT
The present invention relates to a circuit breaker directed for a wiring circuit breaker or motor breaker for starting and stopping a motor or providing protection from overcurrent and, in particular, to an assembly structure of a main body case of a circuit breaker.
First, a circuit breaker for a three-phase circuit including main circuit contact shoes based on two-contacts bridging type is taken as an example, and the assembly structure of a conventional example thereof is shown in FIG.
5
. In this figure, reference numeral
1
denotes a main-body case formed of a resin molding that is divided into three parts including a lower case
1
a
, an upper cover
1
b
, and an intermediate case
1
c
; reference numeral
2
denotes a power supply side main circuit terminal corresponding to each phase; reference numeral
3
denotes a load side main circuit terminal; reference numeral
4
denotes one of the fixed contact shoes connected to a conductor of the main circuit terminal
2
; reference numeral
5
denotes the other fixed contact shoe; reference numeral
6
denotes a movable contact shoe for bridging the fixed contact shoes
4
and
5
; reference numeral
7
denotes a movable contact shoe holder; reference numeral
7
a
denotes a contact spring; reference numeral
8
denotes a cage for guiding and supporting the movable contact shoe holder
7
in the opening and closing directions; reference numeral
9
denotes an arc-extinguishing plate; reference numeral
10
denotes an opening and closing lever for driving the movable contact shoe
6
; reference numeral
11
denotes a toggle type contact shoe opening and closing mechanism including an opening and closing lever
10
; reference numeral
12
denotes a manual operation handle; reference numeral
13
denotes an overcurrent trip device comprising a combination of a solenoid trip device
13
a
that operates instantaneously in response to a short circuit current or the like and a bimetal type thermal trip device
13
b
that performs a time limit operation in response to an overload current, the overcurrent trip device
13
being interposed and connected in series between the fixed contact shoe
5
and the load side main circuit terminal
3
. An activation piece
13
c
of the overcurrent trip device
13
links with the contact-shoe opening and closing mechanism
11
via a trip cross bar and a latch receiver.
The lower case
1
a
of the main-body case
1
has contact shoe mechanisms and arc extinguishing plates for each phase in the lateral direction, and interphase partition walls or barriers molded integrally with the case so as to insulate and isolate the phases. The upper cover
1
b
also has interphase partition walls formed integrally at the front and rear ends thereof so as to insulate and isolate the main circuit terminals
2
for each phase. Furthermore, the main body case is assembled by mounting the opening and closing mechanisms
11
and the overcurrent trip devices
13
in the intermediate case
1
c
, and fitting the intermediate case
1
c
onto the lower case
1
a.
The operation of this circuit breaker is well known. When the operation handle
12
is placed in the ON position, the opening and closing lever
10
recedes, and the movable contact shoe
6
is urged by the contact spring
7
a
so as to elevate with the holder
7
. The movable contact shoe
6
then comes in contact with the fixed contact shoes
4
,
5
to close the circuit. In this closed circuit state, a main circuit current flows from the power supply side main circuit terminal
2
through the fixed contact shoe
4
, the movable contact shoe
6
, the fixed contact shoe
5
, and the overcurrent trip device
13
, in that order, to the load side main circuit terminal
3
. Alternatively, when the operation handle
12
is moved in the opposite direction to be placed in the OFF position, the contact shoe opening and closing mechanism
11
drives the opening and closing lever
10
clockwise to push the movable contact shoe holder
7
downward. This causes the movable contact shoe
6
to be separated from the fixed contact shoes
4
,
5
so as to open the main circuit contacts. On the other hand, when an overload current or a short circuit current flows through the main circuit, the overcurrent trip device
13
operates to release the latch of the contact shoe opening and closing mechanism
10
, whereby the opening and closing lever
10
drives the movable contact shoe
6
in the opening direction so as to cut off the main-circuit current.
The main body case
1
of the circuit breaker, which is constructed by assembling the lower case
1
a
, the upper cover
1
b
, and the intermediate case
1
c
as described above, must be assembled easily, must be sufficiently rigid to accommodate a robot-based automatic assembly method, and must also have an assembly structure that can maintain an interphase insulation proof, specified in the regulations, between the main-circuit terminals for each phase.
The above-described conventional body case
1
, however, has an assembly structure obtained by assembling the above-described parts in each of the lower case
1
a
, the upper cover
1
b
, and the intermediate case
1
c
; placing the parts at the upper cover
1
b
and the intermediate case
1
c
on the lower case
1
a
; and fastening them together using screws. In addition, each divided case includes no positioning or holding means for assembling with other divided case in a predetermined assembled position. Thus, a positioning operation for sequentially placing the intermediate case
1
c
and the upper cover
1
b
on the lower case
1
a
in the assembly process is cumbersome, and before being fastened together by using the screws, the divided cases, which overlap one another, may shift during transfer between the assembly steps. Alternatively, if there is a dimensional error or assembly error in the divided cases, a gap is created between the end surface of the interphase partition wall and the corresponding part that overlaps the end surface when the main body case is assembled. Thus, the required creepage distance of the insulation is not obtained between the main-circuit terminals for each phase.
The present invention has been made in view of the above points, and it is an object thereof to solve these problems in order to provide a rigid circuit breaker that can be assembled easily and that has an improved main body case assembly structure so as to allow the main circuit terminals for the respective phases to be sufficiently insulated.
SUMMARY OF THE INVENTION
To attain the above-described objects, the present invention provides a circuit breaker comprising main circuit terminals, fixed and movable contact shoes, arc extinguishing sections, contact shoe opening and closing mechanisms, and overcurrent trip devices for the respective phases integrated into a main-body case that constitutes a resin molding. The main body case comprises a lower case containing the contact shoes and the arc extinguishing sections for the respective phases, an intermediate case fitted on the lower case and containing power supply and load side main circuit terminal lead-out sections at the front and rear ends of the case, the contact shoe opening and closing mechanisms and the overcurrent trip devices for the respective phases, and an upper cover covering the intermediate case. The lower case and the upper cover have interphase partition walls formed integrally therewith so as to separate the phases. The intermediate case has pocket shaped sockets formed on a top-surface side thereof, in which the tips of the interphase partition walls of the upper cover are fitted when the main-body case is assembled, and the intermediate case also has recessed groove sections formed on a bottom-surface side thereof that fit over the upper edges of the interphase partition walls provided in the lower case. The embodiments are formed as follows.
(1) The main body case is assembled by assembling the upper cover and the lower case so that they surround the inter
Kuboyama Katsunori
Takahashi Tatsunori
Uchida Naoshi
Fuji Electric & Co., Ltd.
Kanesaka & Takeuchi
Tibbits Pia
Tso Edward H.
LandOfFree
Circuit breaker does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Circuit breaker, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Circuit breaker will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3090251