Electricity: circuit makers and breakers – Contact moved by sudden release of stored energy
Reexamination Certificate
2000-10-26
2002-10-29
Friedhofer, Michael (Department: 2832)
Electricity: circuit makers and breakers
Contact moved by sudden release of stored energy,
C218S154000
Reexamination Certificate
active
06472627
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a vacuum circuit breaker, in particular to a switching mechanism of a vacuum circuit breaker. In more particular, the present invention relates to a switching mechanism of a vacuum circuit breaker which is capable of guaranteeing the credibility of its operation by restraining distortion of each component and installing additional components easily in order to perform multifunction.
2. Description of the Prior Art
Generally, a circuit breaker is for switching an electric circuit in order to protect a load unit or a load line from abnormal current caused by abnormal situations such as a short circuit occurrence on electric circuits from a power plant or a substation to an electric facility of a consumer, the circuit breaker is divided into an AC circuit breaker and a DC circuit breaker according to an applied line, and it is divided into a vacuum circuit breaker and a gas circuit breaker according to an arc shielding medium when the contact is switching.
Generally, inside of the circuit breaker is vacuum or is filled with an insulating material, and an arc-extinguishing unit for shielding arc generated in the switching operation of a fixed contactor and a movable contactor installed in the vacuum area or insulating material filled area is disposed in the circuit breaker. A switching mechanism for providing driving force is connected to an extended end of the movable contactor exposed-installed from the sealed area in order to contact or separate the movable contactor to/from the fixed contactor.
The conventional switching mechanism for the vacuum circuit breaker will now be described with reference to accompanying FIG.
1
. The construction and operation of the conventional switching mechanism for the vacuum circuit breaker is referable in the U.S. Pat. No. 5,140,117.
In the conventional switching mechanism for the vacuum circuit breaker, the end portion of a switch lever
111
having a long plate shape is connected to a movable contact portion
105
, the switch lever
111
is installed centering around a first rotating shaft
113
so as to be movable to a turn-ON position or turn-OFF position where the movable contactor
105
and fixed contactor
103
are mutually contacted or separated in order to contact or separate the movable contactor
105
to/from the fixed contactor
103
. A lever driving unit
121
comprises a cut-off spring
117
coupled to the switch lever
111
in order to drive the switch lever
111
. One end portion of an arm
115
is coupled to the other end portion of the switch lever
111
, the other end portion of the arm
115
is contacted to the lever driving unit
121
. A slave roller
116
is coupled to a free end portion as the other end portion of the arm
115
so as to be rotatable in order to be transferred by contacting a cam. The cut-off spring
117
is combined to the first rotation shaft
113
with a certain distance in order to press the switch lever
111
elastically to the turn-OFF position.
Hereinafter, the structure of the lever driving unit
121
will now be described in detail.
Conventionally, the lever driving unit
121
of the switching mechanism for the circuit breaker comprises a second rotating shaft
124
fixed on a base plate
121
a
. An end portion of a turn-on spring
135
is combined to the second rotating shaft
124
. The cam
129
is coupled to the rotating shaft
131
coupled to the other end portion of the turn-on spring
135
so as to be rotatable, and performs a relative motion by contacting mutually to the slave roller
116
. A supporting unit
123
is coupled to the rotating shaft
131
so as to be rotatable in order to rotate centering around the turn-on spring
135
. A turn-on latch
137
is coupled to the side of the cam
129
so as to be rotational in order to make the turn-on spring
135
maintain an extension state by restraining the rotation of the cam
129
. A trip latch
139
is installed on the free end portion of the supporting unit
123
in order to prevent the supporting unit
123
from rotating by being pressed by the cut-off spring
117
. A stopper
127
is installed on the side of the trip latch
139
in order to restrain the rotation of the supporting unit
123
by contacting mutually with the supporting unit
123
.
The cam
129
is installed so as to rotate centering around the rotating shaft
131
projected from the plate surface of the supporting unit
123
, and the other end portion of the turn-on spring
135
is combined to the side of the cam
129
in order to rotate the cam
129
.
And, a stopper pin
133
is protrusively disposed on the side surface of the cam
129
, a roller
134
is installed on the stopper pin
133
so as to be rotational in order to contact the free end portion of the turn-on latch
137
.
Hereinafter, the operation of the conventional switching mechanism for the vacuum circuit breaker will now be described.
First, in order to make the movable contactor contact to the fixed contactor
103
, the turn-on
137
rotates in order to separate from the roller
134
of the stopper pin
133
of the cam
129
.
By the above said operation, the turn-on latch
137
is separated from the roller
134
, as depicted in
FIG. 2
, at the same time the cam
129
rotates to the clockwise direction by the tensile force of the turn-on spring
135
.
According to the rotation of the cam
129
, the slave roller
116
is pressed so as to separate from the rotating shaft
131
of the cam
129
, accordingly the switch lever
111
rotates toward the turn-ON position centering around the first rotating shaft
113
.
According to the rotation of the switch lever
111
, the fixed contactor
103
and movable contactor
105
are contacted each other, the cut-off spring
117
is elastically energized by being extended according with the rotation of the switch lever
111
.
On the contrary, in order to make the movable contactor
105
separate from the fixed contactor
103
, the trip latch
139
rotates in order to separate from the end portion of the supporting unit
123
.
According to the rotation, when the trip latch
139
is separated from the supporting unit
123
, as depicted in
FIG.2
, the switch lever
111
rotates to the counter clock-wise direction centering around the first rotating shaft
113
by the tensile force of the cut-off spring
117
. According to this, the supporting member
123
rotates temporarily centering around the second rotating shaft
124
, but the rotation of the supporting unit
123
is stopped by contacting to the stopper
127
.
Accordingly, according to the rotation of the switch lever
111
, the movable contactor
105
is separated from the fixed contactor
103
.
However, in the conventional vacuum circuit breaker, the supporting unit rotates centering around the second rotating shaft by the tensile force of the cut-off spring, and the rotation is stopped by contacting with the stopper
127
with an impact on the both supporting unit
123
and stopper
127
. When the operation is performed repeatedly, the distortion and separation of the construction parts including the cam can occur due to the impact force caused by the contact between the supporting unit
123
and stopper
127
. And, it may causes below problems.
First, the credibility of the apparatus can be lower because the turn-on or
Turn-off operation may not be performed smoothly due to the distortion of the construction parts caused by the impact force.
Second, in the conventional vacuum circuit breaker, the eccentric-installed switch lever and arm supported by the cut-off spring and the cam supported by the turn-on spring are suspended on the lower portion of the each spring, and the fixed supporting position for each spring is same as upper position.
Moreover, the switch lever is made with a steel plate having long length and the cam is made with the steel plate having long width, the gravity of the switch lever and cam have a bad effect on the compression/extension operation of the springs for contacting or separating the movable contac
Birch & Stewart Kolasch & Birch, LLP
Friedhofer Michael
LG Industrial Systems Co. Ltd.
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