Circuit breaker

Details Circuit breaker Circuit breaker

2003-04-15

2004-11-16

Donovan, Lincoln (Department: 2832)

Electricity: magnetically operated switches, magnets, and electr

Electromagnetically actuated switches

Automatic circuit-interrupting devices

C335S132000

Reexamination Certificate

active

06819206

ABSTRACT:

BACKGROUND OF THE INVENTION AND RELATED ART STATEMENT
The present invention relates to a circuit breaker such as an auto-breaker, and more particularly to a trip indicating means thereof.
A circuit breaker has an over current tripping device for protecting a circuit and a device from an over current through tripping a switching mechanism to open a contact when an over current caused by overloading or short circuit in a main circuit is detected. The over-current tripping device has a time delay tripping device (bimetal type) that trips the switching mechanism with a delay corresponding to a magnitude of an overload current, and an instantaneous tripping device (electromagnetic type) that trips the switching mechanism instantaneously in response to a large current such as a short circuit current.
As an option, an alarm switch may be attached to the circuit breaker for indicating that the switching mechanism trips instantaneously when the short circuit current flows. When the circuit breaker trips in response to the short circuit current, the alarm switch attached to the circuit breaker sends a signal to the outside indicating the tripping.
With reference to FIGS.
6
(
a
),
6
(
b
),
7
and
8
, a construction, and operation of the circuit breaker and the alarm switch attached to a main body of the circuit breaker will be explained. In FIGS.
6
(
a
) and
6
(
b
), a reference numeral
1
denotes a circuit breaker; a reference numeral
2
denotes a housing of the main body of the circuit breaker
1
; a reference numeral
3
denotes a manual operating handle attached to a housing cover of the housing
2
; a reference numeral
4
denotes an alarm switch attached to a side of the circuit breaker
1
; and a reference numeral
5
denotes a trip indicating rod incorporated in the alarm switch
4
. The trip indicating rod
5
is normally disposed inside a housing of the alarm switch
4
. When the circuit breaker
1
trips instantaneously in response to the short circuit current, the trip indicating rod
5
is protruded from an upper side of the housing of the alarm switch
4
to indicate that the circuit breaker
1
instantaneously trips.
FIG. 7
is an assembly showing structures of a switching mechanism and an over-current tripping device incorporated in the circuit breaker
1
. In
FIG. 7
, a reference numeral
6
denotes a switching mechanism for contacts: a reference numeral
6
a
denotes a swing type latch receiver incorporated in the switching mechanism
6
; a reference numeral
6
b
denotes a transmission gear connected to the operating handle
3
; a reference numeral
7
denotes a bimetal type time delay tripping device; a reference numeral
8
denotes an electromagnetic instantaneous tripping device; a reference numeral
8
a
denotes an electromagnetic coil; a reference numeral
8
b
denotes a plunger; a reference numeral
8
c
denotes a trip actuator attached to the plunger
8
b
; and a reference numeral
9
denotes a trip member for connecting the trip actuator
8
c
of the instantaneous tripping device
8
to the latch receiver
6
a
of the switching mechanism
6
. The trip member
9
slides up and down to drive the latch receiver
6
a
to a release position in response to the operation of the instantaneous tripping device
8
. The bimetal type time delay tripping device
7
is constructed such that an operating end of a bimetal thereof is connected to the latch receiver
6
a
via a temperature compensating bimetal, which is also used as an actuator lever, without going through the trip member
9
.
FIG. 8
is a view showing a structure of the trip member
9
and a connection structure between the trip member
9
and the alarm switch
4
. The trip member
9
formed of a resin plate is guided and supported to slide up and down in the breaker housing
2
, and is urged upward by a return spring
10
inserted between the trip member
9
and a bottom of the breaker housing
2
. The trip actuator
8
c
of the instantaneous tripping device
8
faces a shoulder part of the trip member
9
. An end of the latch receiver
6
a
is inserted into a window hole with a cam surface formed on a surface of the trip member
9
. The alarm switch
4
is comprised of the trip indicating rod
5
and an actuator lever
4
a
connected to an alarm contact point (not shown). An end of the actuator lever
4
a
is protruded into the housing
2
of the circuit breaker
1
and inserted into a concaved groove formed in a side of the trip member
9
.
With the above arrangement, when a large current such as the short circuit current flows through a main circuit of the circuit breaker
1
, the instantaneous tripping device
8
in
FIG. 7
is operated to cause the trip actuator
8
c
thereof to push down the trip member
9
against the force of the return spring
10
. Then, the latch receiver
6
a
tilts leftward to unlock a latch of the switching mechanism
6
(refer to
FIG. 7
) to cause the circuit breaker
1
to trip instantaneously. When the trip member
9
moves downward during the tripping, the actuator lever
4
a
of the alarm switch
4
turns counterclockwise. In response to the movement of the actuator lever
4
a
, the alarm contact point is turned on to transmit a trip signal to the outside, and the trip indicating rod
5
is pressed by a spring (not shown) to protrude from the housing
2
to indicate that the circuit breaker
1
instantaneously trips. The structure and operation of the switching mechanism
6
have been disclosed in detail in Japanese Patent Publication (KOKAI) No. 2001-23499 filed by the applicant of the present invention.
Further, the operating handle
3
of the circuit breaker
1
shown in FIGS.
6
(
a
) and
6
(
b
) is turned to a TRIP position located between an ON position and an OFF position in response to the tripping of the circuit breaker
1
. Thus, it is possible to visually confirm that the circuit breaker
1
is tripped according to the position of the operating handle
3
. In this case, it is difficult to determine whether the circuit breaker is tripped due to the overload current or the short circuit current.
As described above, the main body of the conventional circuit breaker can not indicate that the circuit breaker trips instantaneously. It is therefore necessary to provide the alarm switch in the main body of the circuit breaker as an attachment (option) so as to indicate whether the circuit breaker trips instantaneously. Therefore, even if a user does not need a function of transmitting an electric signal indicating that the circuit breaker trips instantaneously, and just needs to visually confirm that the circuit breaker trips instantaneously, the user has to obtain a space for installing the alarm switch.
It is therefore an object of the present invention to provide a circuit breaker that makes it possible to visually confirm that, the circuit breaker instantaneously trips due to a short circuit current only by adding a simple part to a tripping mechanism of the circuit breaker, thereby improving safety by holding the tripping mechanism at a trip position until the breaker is reset.
Further objects and advantages of the invention will be apparent from the following description of the invention.
SUMMARY OF THE INVENTION
To attain the above object, according to the present invention, a circuit breaker includes a switching mechanism for switching contacts, a manual operating handle connected to the switching mechanism, and an instantaneous tripping device for detecting a short circuit current and opening the contacts of a main circuit. In the circuit breaker, the instantaneous tripping device and a latch receiver of the switching mechanism are connected with each other via a trip member capable of sliding up and down. The trip member slides in response to a movement of the instantaneous tripping device, and drives the latch receiver to a release position to trip the switching mechanism. Further, the circuit breaker includes a trip indicating member attached to the trip member, and a trip indicating window formed in a breaker housing and facing the trip indicating

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