Electricity: magnetically operated switches – magnets – and electr – Electromagnetically actuated switches – Automatic circuit-interrupting devices
Reexamination Certificate
2002-08-01
2003-11-04
Enad, Elvin (Department: 2832)
Electricity: magnetically operated switches, magnets, and electr
Electromagnetically actuated switches
Automatic circuit-interrupting devices
C335S132000, C340S638000
Reexamination Certificate
active
06642820
ABSTRACT:
BACKGROUND OF THE INVENTION AND RELATED ART STATEMENT
The invention relates to a protective switch for use as a breaker or a switch to protect a low-voltage indoor electric line or a device from over-current. More particularly, the invention relates to a tripping device of the protective switch.
Generally, a protective switch of this kind has an over-current tripping device incorporated therein, which acts on a locking member of a switching mechanism upon detection of over-current and releases the locked switching mechanism to cause a breaking action (tripping). Usually, the over-current tripping device carries out time-delay tripping in which an overload current is tripped with lapse of a delay time corresponding to a current value, and carries out instantaneous tripping in which large current such as short-circuit current is tripped instantaneously. An alarm switch may be attached to the protective switch as an auxiliary device. If the protective switch is instantaneously tripped due to a large accidental current, the alarm switch sends an electric signal to warn an external device, and further indicates mechanically on a front surface of the switch.
Examples of a tripping control device for the protective switch include a voltage tripping device and an under-voltage tripping device. The voltage tripping device is used to control the protective switch from a distance, and trips the protective switch when a predetermined voltage is applied thereto. On the other hand, the under-voltage tripping device constantly monitors a circuit voltage, and if the circuit voltage becomes lower than a specified value, the under-voltage tripping device trips the protective switch. An alarm switch and tripping control device are ordinarily mounted on a side of a body of the protective switch.
FIG. 5
is a longitudinal sectional view showing a conventional triple pole protective switch that includes an electromagnetic over-current tripping mechanism with an instantaneous tripping characteristic (hereinafter referred to as “instantaneous tripping mechanism”) and a thermally-actuated over-current tripping mechanism with a time-delay tripping characteristic (hereinafter referred to as “time-delay tripping mechanism”) as over-current tripping devices. In
FIG. 5
, each of phase circuits housed in a switch body housing
1
is comprised of a pair of fixed contacts
2
,
3
and a movable contact
4
that bridges the pair of fixed contacts
2
,
3
. The movable contact
4
is pressed against the fixed contacts
2
,
3
by a contact spring
5
comprised of a compression coil spring inserted between the movable contact
4
and a housing bottom
1
a
to close the circuit. The movable contact
4
is held by a three-phase integrated movable contact holder
6
formed of an insulating material, and the movable contact holder
6
is movably guided by the housing
1
in a vertical direction with respect to the housing bottom in a vertical direction in FIG.
5
.
A power supply-side terminal
7
is integrated with the fixed contact
2
, and the fixed contact
3
is connected to a lower end of a bimetal
8
a
of a time-delay tripping mechanism
8
. An upper end of the bimetal
8
a
is connected to one end of a heater
8
b
. The heater
8
b
is wound on the bimetal
8
a
through an insulating material (not shown) and the other end of the heater
8
b
is connected to one end of an electromagnetic coil
9
a
of an instantaneous tripping mechanism
9
. The other end of the electromagnetic coil
9
a
is connected to a load-side terminal
10
. The instantaneous tripping mechanism
9
is constructed such that the electromagnetic coil
9
a
wound around a cylindrical bobbin
9
c
is positioned vertically with respect to the housing bottom
1
a
in a U-shaped yoke
9
b
, and a cylindrical plunger
9
d
is slidably inserted into the bobbin
9
c
. An operating member
9
e
is joined to a head of the plunger
9
d
, and the plunger
9
d
forced upward in
FIG. 5
by a return spring
9
f
is fixed with the operating member
9
e
being in contact with an upper end of the yoke
9
b.
A switching mechanism
11
has a pair of right and left opening and closing levers
13
that rotate around a switching shaft
12
. Ends of the levers
13
stay at both sides of the instantaneous tripping mechanism
9
at a central pole and above the movable contact holder
6
in the circuit-closed state as shown in FIG.
5
. The switching mechanism
11
is operated by a butterfly-shaped operating handle
14
projecting from the housing
1
, and a latch
17
is locked at a latch receiver
26
while the pair of breaking springs
25
formed of a torsion spring is wound.
FIG. 6
is a front view showing a reset state of the switching mechanism
11
, taken along line (
6
)—(
6
) in
FIG. 5
, and
FIG. 7
is a front view showing a tripping state of the switching mechanism in FIG.
6
. The switching mechanism
11
is constructed as an integral unit such that mechanical parts are supported on a frame
15
having front and rear side plates (the front side plate is omitted from FIGS.
6
and
7
). The operating handle
14
is supported on the frame
15
such that it is capable of pivoting around a handle shaft
16
, and the latch
17
is rotatably supported on the handle shaft
16
. An upper end of an upper link
18
is connected to the operating handle
14
via a shaft
19
, and an upper end of a lower link
20
is connected to a lower end of the upper link
18
via one end
21
a
of a U-shaped pin
21
. The U-shaped pin
21
has the other end
21
b
rested on the latch
17
so that the latch
17
locks the upper link
18
and the lower link
20
. The upper link
18
and the lower link
20
constitute a toggle link.
A transmission pin
22
is connected to a lower end of the lower link
20
, and both ends of the transmission pin
22
are slidably inserted into a slot
23
formed in the side plates of the frame. Another transmission pin
24
is connected to the switching levers
13
such that the pin
24
crosses a transmission pin
16
. The pair of switching levers
13
is connected to the switching shaft
12
, which has both ends supported on the housing
1
, with an interval formed therebetween, and the transmission pin
24
is bridged between the right and left switching levers
13
. The switching shaft
12
is rotatably supported on the housing
1
, and the pair of breaking springs
25
is fitted into the switching shaft
12
with one end of the breaking spring
25
being engaged with the transmission pin
24
and the other end thereof being engaged with the frame
15
. The breaking spring
25
is twisted in an ON state in
FIG. 6
, and applies a push-up force P from the transmission pin
24
to the transmission pin
22
so as to rotate the switching levers
13
clockwise in FIG.
5
.
The push-up force P causes the transmission pin
22
of the lower link
20
to move upward along the slot
23
. As a result, the entire lower link
20
tries to rotate counterclockwise in
FIG. 6
, but is kept in a position shown in
FIG. 6
since the U-shaped pin
21
locks the upper end thereof. The lower link applies a tensile force Q to the latch
17
via the U-shaped pin
21
. As a result, the latch
17
tries to rotate clockwise in
FIG. 6
around the handle shaft
16
, but is kept in a position shown in
FIG. 6
since it is locked by the latch receiver
26
serving as a locking member.
The latch receiver
26
is a vertically extended plate having a pair of right and left bent arms
26
a
at a substantially intermediate position thereof, and has a quadrate window hole formed in the plate near the arms
26
a
. The latch receiver
26
is rotatably supported on the frame
15
via a shaft
27
extending through the arms
26
a
, and has an engagement portion
26
b
, positioned at the lower edge of the window hole to engage an L-shaped portion
17
a
of the latch
17
to lock the latch
17
. In response to pressure applied by the latch
17
, the latch receiver
26
tries to rotate clockwise in
FIG. 6
, but is inhibited from rotating and kept in an upright position shown in
Asakawa Koji
Emura Takeshi
Kawata Hisao
Kuboyama Katsunori
Enad Elvin
Fuji Electric & Co., Ltd.
Kanesaka & Takeuchi
Rojas Bernard
LandOfFree
Protective switch does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Protective switch, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Protective switch will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3149129