TECHNICAL FIELD
[0001] The utility model belongs to the field of low-voltage apparatuses, in particular
to a miniature circuit breaker.
BACKGROUND
[0002] An arc extinguishing system of a miniature circuit breaker generally comprises an
arc extinguishing chamber and an arc runner which are composed of arc extinguishing
grid-plates, and an arc blowing device configured to guide an electric arc to the
arc extinguishing chamber. In particular for a conventionally used miniature circuit
breaker with an alternating current of 50Hz, a rated current up to 63A and a rated
voltage not exceeding 400V, an arc extinguishing capability of the arc extinguishing
system is associated with a breaking capability of the circuit breaker, and the arc
extinguishing capability also involves many factors. According to the existing miniature
circuit breaker, a plurality of arc extinguishing grid-plates are manufactured into
an arc extinguishing chamber of an integrated structure firstly, and then the arc
extinguishing chamber is mounted into the circuit breaker. In this way, there are
many problems arising: firstly, the arc extinguishing chamber of the integrated structure
is inconvenient to process and high in manufacturing cost; secondly, the structure
of the arc extinguishing chamber is single, and the same type of arc extinguishing
chamber may be used only regardless of the current specification, which cannot meet
different arc extinguishing requirements of different types of circuit breaker products,
thereby affecting the performances of the circuit breaker product; for example, the
use of a large arc extinguishing chamber for a small-sized product will affect the
miniaturization requirement, and the use of a small arc extinguishing chamber for
a large-sized product will affect the breaking capability; thirdly, a high-temperature
airflow in the arc extinguishing chamber cannot be discharged smoothly, this is because
the structure of the arc extinguishing chamber causes that air discharge openings
behind the arc extinguishing chamber cannot be made to be large, thereby affecting
an arc extinguishing effect.
[0003] At the same time, the design of an arc extinguishing system of the existing circuit
breaker focuses on an arc extinguishing chamber and front structures in front thereof,
such as an arc striking structure and an arc blowing structure, but the discharge
of high temperature airflow in the arc extinguishing chamber is generally ignored.
However, it has been found through experiments that the discharge of the high-temperature
airflow is essential for the arc extinguishing effect, in which the rear structures,
such as an air discharge opening behind the arc extinguishing chamber, an air outlet
in a housing, and an air flow passage between the air discharge opening of the arc
extinguishing chamber and the air outlet of the housing are involved. The rear structures
have the adverse effect mainly in that: since the hot air flows ejected by the electric
arc after passing through the arc extinguishing chamber form mutual interference at
the air discharge opening, the discharge of the hot air flows is not smooth, thereby
affecting the arc extinguishing effect of the circuit breaker. Therefore, people use
the existing miniature circuit breaker equipped with a large-sized arc extinguishing
chamber. However, since the arc extinguishing chamber is composed of a plurality of
arc extinguishing grid-plates, the volume of the arc extinguishing chamber is increased
to make the structure of the arc extinguishing chamber complicated, thereby increasing
the processing cost and not conforming to the miniaturization design trend of the
miniature circuit breaker. Moreover, the optimal arc extinguishing effect and the
optimal breaking capability of the circuit breaker cannot be obtained owing to the
pressure of the hot air flow in case where air cannot be discharged smoothly, such
that the impact damage to the arc extinguishing system including the arc extinguishing
chamber is aggravated. In order to strengthen the impact resistance of the arc extinguishing
system, the complexity of the arc extinguishing structure and the increase of the
manufacturing cost are also caused.
SUMMARY
[0004] The technical problem to be solved by the utility model is to provide a miniature
circuit breaker with respect to the defects that arc striking and air discharging
effects of the hot air flow at the air discharge opening of the above-mentioned arc
extinguishing chamber are poor and can be remedied only by increasing the volume of
the air extinguishing chamber in the prior art. By adopting a plurality of air flow
passages disposed between an air outlet and the arc extinguishing chamber, an optimal
arc extinguishing effect and an optimal breaking capability can be obtained, and the
volume of the arc extinguishing chamber can be appropriately reduced.
[0005] A miniature circuit breaker comprises a housing having an air outlet, wherein a plurality
of arc extinguishing grid-plates is mounted in an arc extinguishing chamber 10; the
arc extinguishing chamber 10 is fixedly connected to the housing; an air discharge
opening 101 is formed in a rear plate of the arc extinguishing chamber 10; a rear
arc extinguishing structure is disposed between the air discharge opening 101 of the
arc extinguishing chamber 10 and the air outlet of the housing; the rear arc extinguishing
structure comprises a plurality of air flow passages disposed between the air discharge
opening 101 of the arc extinguishing chamber 10 and the air outlet of the housing,
such that high-temperature air flows in the arc extinguishing chamber 10 pass through
the air discharge opening 101 and the plurality of air flow passages and are then
discharged from the air outlet.
[0006] Preferably, the air flow passages of the rear arc extinguishing structure comprises
a exhaust passage 132 and a plurality of guide passages 131; each guide passage 131
is communicated with at least one air discharge opening 101 and at least one exhaust
passage 132; the exhaust passage 132 is communicated with the air outlet.
[0007] Preferably, the rear arc extinguishing structure comprises a plurality of guide passages
131, wherein the plurality of guide passages 131 are in one-to-one correspondence
with the plurality of air discharge openings 101 behind the arc extinguishing chamber
10.
[0008] Preferably, the rear arc extinguishing structure comprises a plurality of guide passages
131 and a plurality of exhaust passages 132, where the number of the exhaust passages
132 is less than that of the guide passages 131; the plurality of guide passages 131
are in one-to-one correspondence with the plurality of air discharge openings 101
behind the arc extinguishing chamber 10; each exhaust passage 132 is communicated
with at least one guide passage 131 and at least one air outlet.
[0009] Preferably, the plurality of guide passages 131 is formed by partitioning with a
plurality of horizontal partitioning ribs 134; the plurality of horizontal partitioning
ribs 134 are disposed in parallel with the arc extinguishing grid-plates to form a
grid-type heat dissipation structure.
[0010] Preferably, the air flow passages of the rear arc extinguishing structure are a plurality
of guide passages 131 which are disposed between the air discharging openings 101
of the arc extinguishing chamber 10 and the air outlets of the housing and partitioned
by arc-shaped partitioning ribs 133.
[0011] Preferably, a ratio of a length of each guide passage 131 of the rear arc extinguishing
structure to a length of the arc extinguishing chamber 10 is 0.2 to 0.5.
[0012] Preferably, a plurality of arc extinguishing grid-plates is disposed in the arc extinguishing
chamber 10; an arc extinguishing gap is formed between every two adjacent arc extinguishing
grid-plates; a plurality of air discharge openings 101 is formed in the rear plate
of the arc extinguishing chamber 10; each air discharge opening is in one-to-one correspondence
with one arc extinguishing gap; the plurality of air discharge openings 101 in the
rear plate of the arc extinguishing chamber 10 are disposed on two sides of the rear
plate in two columns; the two columns of air discharge openings 101 are alternately
disposed in staggered layers.
[0013] Preferably, four air outlets are formed in one side of the housing, i.e., a first
air outlet 141 close to the top of a wiring base of a wiring terminal at one side
of the housing, a second air outlet 142 close to the bottom of the wiring base, as
well as a third air outlet 143 and a fourth air outlet 144 which are positioned on
the sidewall and the bottom edge of the bottom of one side of the housing respectively;
a space between the exhaust passages 132 and the four air outlets is partitioned by
three arc-shaped partitioning ribs 133 to form four guide passages 131 which are in
one-to-one correspondence with the four air outlets, wherein a ventilation space is
preserved at the end part of the arc-shaped partitioning rib 133 that isolates the
third air outlet 143 from the fourth air outlet 144, such that the third air outlet
143 is communicated with the fourth air outlet 144.
[0014] Preferably, the miniature circuit breaker further comprises a front arc extinguishing
structure disposed in the housing; the front arc extinguishing structure comprises
a plurality of arc striking grooves which is disposed between an opening in the front
side of the arc extinguishing chamber and a static contact.
[0015] When the miniature circuit breaker is implemented, the air flows flowing out from
the grid-plates of the arc extinguishing chamber can be prevented from interfering
with each other by disposing a plurality of air flow passages in front of the air
outlets of the circuit breaker and behind the arc extinguishing chamber, hot air flows
can be prevented from interfering with each other at the air discharge openings, and
heat energy can be quickly dissipated, thereby quickly extinguishing electric arcs,
enhancing an arc extinguishing effect of an arc extinguishing system and a breaking
capability of the circuit breaker, and reducing the volume of the arc extinguishing
chamber.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] The present utility model will be further described below with reference to the accompanying
drawings and embodiments, and the advantages and features of the present utility model
can be seen clearly from the description of the embodiments shown in the accompanying
drawings. In the drawings,
Fig. 1 is a perspective view showing an internal overall structure of a miniature
circuit breaker of the utility model, in which a fixed structure of arc extinguishing
grid-plates 2 and a base 1 is shown.
Fig. 1 is a perspective view of a grid-plate fixing structure A, a rear arc extinguishing
structure B and a front arc striking structure C in the embodiment shown in Fig. 1.
Fig. 3 is a plan view of Fig. 1.
Fig. 4 is a plan view of Fig. 2.
Fig. 5 is a perspective view of the arc extinguishing grid-plates 2 in the embodiment
shown in Fig. 1.
Fig. 6 is a perspective view of a housing cover 6.
Fig. 7 is an enlarged view of a part E in Fig. 2.
Fig. 8 is an enlarged view of a part F in Fig. 6.
Figs. 9-10 illustrate another embodiment of the utility model.
Fig. 11 is a perspective view of an arc extinguishing chamber in Fig. 9.
DETAILED DESCRIPTION
[0017] As can be seen from the perspective view of the overall internal structure of the
miniature circuit breaker shown in Fig. 1 and the perspective view of the housing
cover 6 shown in Fig. 6, the miniature circuit breaker provided with multi-positioned
arc extinguishing grid-plates of the utility model comprises a housing composed of
a base 1 and the housing cover 6. The base 1 and the housing cover 6 can be statically
connected by any known means (such as screws, snaps, etc.).A static contact 3 and
a movable contact 4 are disposed in a cavity formed between the base 1 and the housing
cover 6. A handle drives the movable contact 4 to swing by an operating mechanism
7 to be in contact with and to be separated from the static contact 3to realize the
on/off of a circuit.
[0018] The circuit breakers belong to products with different sizes and different current
specifications according to users' demands, wherein the demands for arc extinguishing
systems are different. The miniature circuit breaker provided with multi-positioned
arc extinguishing grid-plates of the utility model has a beneficial effect: the housing
is provided with a grid-plate fixing structure A for fixing the arc extinguishing
grid-plates 2, and the arc-extinguishing grid-plates 2 are directly and statically
connected to the housing through the grid-plate fixing structure A, such that a gap
2a which is communicated with an air outlet in the housing is formed between every
two adjacent arc extinguishing grid-plates 2.By disposing the grid-plate fixing structure
A, it is possible to dispose different numbers of arc extinguishing grid-plates according
to different current specifications, without the need of making the arc extinguishing
chamber integral, thereby facilitating processing and optimizing the structures of
the products. The arc-extinguishing grid-plates 2 are directly and statically connected
to the base 1 and the housing cover 6respectively through the grid-plate fixing structure
A, such that a plurality of gaps 2a is formed between every two adjacent arc extinguishing
grid-plates 2 by means of the static connection. The term "multi-positioned" as described
herein means that the number of arc extinguishing grid-plates 2 may be determined
according to different arc extinguishing requirements of different types of circuit
breaker products. In addition, by directly and statically connecting the arc extinguishing
grid-plates to the base 1 and the housing cover 6 respectively, the arc extinguishing
grid-plates 2 may be directly fixed on the base 1 and the housing cover 6, without
using an existing arc extinguishing structure in which a plurality of arc extinguishing
grid-plates are fixedly connected together by plate-wall-type elements constituting
an arc extinguishing chamber and without adjusting the housing. It is apparent that,
to realize the diversification of the number of the arc extinguishing grid-plates
2, the key is to use the multi-positioned arc extinguishing grid-plates 2 and the
grid-plate fixing structure A, thereby achieving the beneficial effects including:
the problem that the arc extinguishing chamber is too large or too small can be effectively
overcome, and the excellent arc extinguishing effect is ensured while the miniaturization
requirement is satisfied.
[0019] In order to improve the arc extinguishing effect of the utility model, the miniature
circuit breaker of the utility model further comprises a rear arc extinguishing structure
B and a front arc extinguishing structure C which are disposed inside the housing.
The rear arc extinguishing structure B comprises a plurality of air flow passages
13a, 13b, 13c disposed between the gap 2a between every two of the arc extinguishing
grid-plates 2 on the grid-plate fixing structure A and the air outlet, such that high-temperature
air flows in the gaps 2a are guided through the plurality of air flow passages 13a,
13b, 13c and then discharged from the air outlet. The front arc striking structure
C comprises a plurality of arc striking grooves 16 disposed between the arc extinguishing
grid-plates 2 on the grid-plate fixing structure A and the static contact. As shown
in Figs. 1-4, an instantaneous tripper including an electromagnetic trip device 8
and an overload tripper including a bimetal sheet 9 are also disposed in the housing
of the miniature circuit breaker of this embodiment. A striker of the electromagnetic
trip device 8 corresponds to a lock catch of the operating mechanism. The bimetal
sheet 9 corresponds to a driving rod (not shown in drawings) extending out from the
lock catch. When the electric leakage occurs, the striker of the electromagnetic trip
device 8 pops up and hits the lock catch of the operating mechanism to trip the circuit
breaker; when the circuit is overloaded, the bimetal sheet is bent to pull the lock
catch through the driving rod to trip the circuit breaker. The grid-plate fixing structure
A for fixing the arc extinguishing grid-plates 2 is disposed below the electromagnetic
trip device 8, and the rear arc extinguishing structure B and the front arc striking
structure C are respectively disposed on both sides of the grid-plate fixing structure
A. The static contact 3 having an arc striking structure and an arc striking plate
5 having a V-shaped arc striking angle are respectively disposed above and below the
side, close to the front arc striking structure C, of the grid-plate fixing structure
A. The movable contact 3 is connected to a coil of the electromagnetic trip device
8. The arc striking plate 5 is connected to the bimetal sheet 9. By means of the arc
striking structures, an electric arc can be guided to the arc extinguishing grid-plates
2 rapidly, then a high temperature gas can be discharged rapidly by means of the rear
arc extinguishing structure B and the air outlet, and therefore the arc extinguishing
effect and the breaking capability can be effectively improved.
[0020] The miniature circuit breaker of the utility model has another beneficial effect:
there are a plurality of manners for the grid-plate fixing structure, wherein one
preferred manner is as shown in Figs. 2 and 4: the grid-plate fixing structure A comprises
a plurality of lower fixing grooves 15 formed in the base 1 and a plurality of upper
fixing grooves 65 formed in the housing cover 6 (refer to Figs. 6 and 8), wherein
a lower edge 21 (refer to Fig. 5) of each arc extinguishing grid-plate 2 is fixedly
embedded in each lower fixing groove 15, an upper edge (refer to Fig. 5) of each arc
extinguishing grid-plate 2 is fixedly embedded in each upper fixing groove 65, such
that each arc extinguishing grid-plate 2 is directly and statically connected to the
base 1 and the housing cover 6 by means of the fixed embedding. There are a plurality
of manners for the lower fixing grooves 15 and the upper fixing grooves 65, wherein
one preferred manner is as shown in Figs. 2 to 8: the base 1 is provided with a plurality
of lower fixing ribs 11 (refer to Fig. 7), each lower fixing groove 15 of the grid-plate
fixing structure A as shown in Figs. 2 and 4 is formed by a space between every two
adjacent lower fixing ribs 11, and a height of each lower fixing rib 11 is far less
than a height H of each arc extinguishing grid-plate 2 (refer to Fig. 5); refer to
Fig. 6, a plurality of upper fixing ribs 61 is disposed on the housing cover 6, each
upper fixing groove 65 of the grid-plate fixing structure A is formed by a space between
every two adjacent fixing ribs 61, and a height of each upper fixing rib 61 is far
less than the height H of each arc extinguishing grid-plate 2 (refer to Fig. 5). In
order to ensure that the static connection for fixed embedding between the arc extinguishing
grid-plates 2 and the lower fixing grooves 15 as well as between the arc extinguishing
grid-plates 2 and the upper fixing grooves 65 is not loose under the impact of the
high temperature airflow and also ensure that the gap 2a has a sufficiently large
remaining height (this height is equal to the height H of each arc extinguishing grid-plate
2 minus the height of the lower edge 21 and the height of the upper edge 22), it is
necessary to optimize a dimensional fit between the arc extinguishing grid-plates
2 and the lower fixing grooves 15 as well as between the arc extinguishing grid-plates
2 and the upper fixing grooves 65. There is a plurality of specific manners for optimization,
wherein one preferred manner is as follows: a width D1 (refer to Fig. 7) of each lower
fixing groove 15 of the grid-plate fixing structure A is equal to a thickness d (refer
to Fig. 5) of each arc extinguishing grid-plate 2, and a depth h1 (refer to Fig. 7)
of the lower fixing groove
[0021] 15 is far less than the height H of the arc extinguishing grid-plate 2.A width D6
(refer to Fig. 8) of each upper fixing groove 65 of the grid-plate fixing structure
A is equal to the thickness d of the arc extinguishing grid-plate 2, a length of the
upper fixing groove 65 is equal to the length b of the arc extinguishing grid-plate
2, and a depth h6 (refer to Fig. 8) of each lower fixing groove 65 is far less than
the height H of the arc extinguishing grid-plate 2. As can be seen from the embodiment
shown in Figs. 2 and 7, a height of each lower fixing rib 11 is equal to a depth h1
(refer to Fig. 7) of each lower fixing groove. As can be seen from the embodiment
shown in Figs. 6 and 8, the height of each upper fixing rib 61 is equal to the depth
h6 (refer to Fig. 8) of each upper fixing groove 65. However, in the actually used
grid-plate fixing structure A, the height of each upper fixing rib 61 may be incompletely
equal to the depth h6 of each upper fixing groove 65, but as long as the height of
each upper fixing rib 61 is far less than the depth h6 of each upper fixing groove
65, the gap 2a can be made to have the largest possible remaining height while ensuring
that the static connection is not loose, because the arc extinguishing effect of the
arc extinguishing grid-plates 2 is better as the remaining height increases, and meanwhile,
high temperature airflow in the gap 2a flows to the rear arc extinguishing structure
B more smoothly. The "far less" refers that: the depth h6 of each lower fixing groove
65 may be less than one sixth of the height H of each arc extinguishing grid-plate
2; the depth h6 of each upper fixing groove 15 may be less than one sixth of the height
H of each arc extinguishing grid-plate 2; the height of each upper fixing rib 61 may
be less than one sixth of the height H of each arc extinguishing grid-plate 2; the
height of each lower fixing rib 11 may be less than one sixth of the height H of each
arc extinguishing grid-plate 2.
[0022] The present invention has yet another beneficial effect: the miniature circuit breaker
provided with the multi-positioned arc extinguishing grid-plates further comprises
a rear arc extinguishing structure B disposed in the housing. The rear arc extinguishing
structure B comprises a plurality of air flow passages 13a, 13b, 13c disposed between
the gap 2a between every two of the arc extinguishing grid-plates 2 on the grid-plate
fixing structure A and the air outlet, such that high-temperature air flows in the
gaps 2a are guided through the plurality of air flow passages 13a, 13b, 13c and then
discharged from the air outlet. There is a plurality of manners for the specific structure
of the rear arc extinguishing structure B, wherein a preferred manner is as shown
in Figs. 2 and 4: a plurality of lower partitioning ribs 12 is disposed on the base,
and a plurality of upper partitioning ribs 62 is disposed on the housing cover 6 (refer
to Fig. 6), wherein the upper partitioning ribs 12 are docked with the upper partitioning
ribs 62, such that a space between the base 1 and the housing cover 6 is partitioned
into a plurality of air flow passages 13a, 13b and 13c of the rear arc extinguishing
structure B, and each of the air flow passages 13a, 13b and 13c is communicated with
at least one gap 2a between the arc extinguishing ribs 2 and at least one air outlet
respectively. The rear arc extinguishing structure B has the following beneficial
effects. Firstly, an electric arc is partitioned into arc sections by the plurality
of arc extinguishing grid-plates 2 and the gaps 2a there between. Each arc section
is quickly extinguished in each gap 2a, and a high temperature and high pressure airflow
is formed in the gap 2a.Since the gaps 2a of the arc extinguishing grid-plates 2 are
directly communicated with the plurality of airflow passages 13a, 13b and 13c of the
rear arc extinguishing structure B, and the airflow passages can increase a large
negative pressure space, the high temperature and high pressure airflows in the gaps
2a can be guided into the airflow passages 13a, 13b and 13c in time and quickly, which
can effectively improve the arc extinguishing capability of the arc extinguishing
grid-plates 2.Secondly, since the high-temperature air flows flowing out from the
gaps 2a flow from the plurality of airflow passages 13a, 13b, and 13c to the plurality
of air outlets 14 and 64, respectively, and are then discharged out of the base 1
of the circuit breaker, the high temperature air flows do not interfere with each
other during the flowing discharge process, and can be smoothly and quickly discharged
from the air outlets regardless of the air pressure of the high temperature air flows.
Thirdly, since the plurality of air flow passages 13a, 13b, and 13c are formed by
docking the plurality of lower partitioning ribs 12 with the plurality of upper partitioning
ribs 62, and the partitioning ribs also have the effect of dissipating heat, the cooling
of the high temperature air flows can be effectively accelerated by increasing the
partitioning ribs. Fourthly, since the rear arc extinguishing structure B has the
characteristics of smooth and rapid air discharging and can effectively alleviate
the impact of the airflows, the structure including the arc extinguishing grid-plates
2 is protected from impact damage. Therefore, the utility model can effectively overcome
the following defects of the existing arc extinguishing chamber structure: due to
the narrow air discharge openings behind the arc extinguishing chamber, the high temperature
and high pressure airflows in the arc extinguishing chamber are not easily discharged
from the air discharge openings and also cause the mutual interference of air discharge
at the air discharge openings, resulting in that high temperature and high pressure
air flows remaining in the arc extinguishing chamber, which are difficult to discharge,
pose a serious threat to the arc extinguishing effect, such as causing the electric
arc to repeatedly reignite.
[0023] In order to further improve an effect of draining high temperature and high pressure
air flows of the rear arc extinguishing structure B, a preferred structural solution
is as shown in Figs. 3 and 4. The housing is internally provided with a plurality
of air outlets and a plurality of air flow passages 13a, 13b and 13c. Each of the
air flow passages 13a, 13b and 13c is communicated with at least one gap 2a between
the arc extinguishing grid-plates 2 and at least one air outlet. Specifically, four
air outlets are formed in one side of the housing, i.e., a first air outlet 141 close
to the top of a wiring base of a wiring terminal at one side of the housing, a second
air outlet 142 close to the bottom of the wiring base, as well as a third air outlet
143 and a fourth air outlet 144 which are positioned on the sidewall and the bottom
edge of the bottom of one side of the housing respectively. The first air outlet 141
and the second air outlet 142 are completely isolated from the third air outlet 143
and the fourth air outlet 144 by means of the first partitioning rib 121 to form the
upper air flow passage 13c and the lower air flow passage. The first air outlet 141
and the second air outlet 142 are communicated with the gaps 2a between more than
half of the arc extinguishing grid-plates 2. The second partitioning rib 122 partially
isolates the third air outlet 143 from the fourth air outlet 144 to guide the high
temperature airflows, and separates the lower airflow passage to form the first lower
airflow passage 13a and the second lower airflow passage 13b.One end of the second
partitioning rib 122 is connected to the gap 2a between the arc extinguishing grid-plates
2, the other end thereof extends towards a space between the third air outlet 143
and the fourth air outlet 144, and a ventilation space is left to make the third air
outlet 143 and the fourth air outlet 144 communicated. It is apparent that such structure
enables the high temperature and high pressure airflows to be discharged from the
four air outlets through the first lower air flow passage 13a, the second lower air
flow passage 13b, and the upper air flow passage 13c to further improve smooth and
rapid discharge and prevent the interference.
[0024] The utility model has a further beneficial effect: the miniature circuit breaker
further comprises a front arc striking structure C disposed in the housing. As shown
in Fig. 3, the front arc striking structure C comprises a plurality of arc-shaped
arc striking grooves 16 which is disposed between the arc extinguishing grid-plates
2 on the grid-plate fixing structure A and the movable contact. The plurality of arc-shaped
arc striking grooves 16 is in one-to-one correspondence with the gaps 2a between the
plurality of arc extinguishing grid-plates 2. Specifically, the base 1 is provided
with a plurality of upper arc striking ribs, and the housing cover 6 is correspondingly
provided with a plurality of lower arc striking ribs. After the base 1 and the housing
cover 6 are connected correspondingly, a space where the movable contact 3 is in contact
with the movable contact 4 is formed between the upper arc striking ribs and the lower
arc striking ribs. The movable contact 3 is disposed between the upper arc striking
ribs and the lower arc striking ribs, and the movable contact 4 swings between the
upper arc striking ribs and the lower arc striking ribs in a direction close to the
arc extinguishing grid-plates 2. By means of the plurality of arc-shaped arc striking
grooves 16, electric arcs generated by the movable contact and the static contact
are rapidly guided to the gaps 2a between the plurality of arc extinguishing grid-plates
2 respectively, thereby improving the air flow passages of the electric arcs, improving
the arc extinguishing capability of the circuit breaker and avoiding the assembly
of elements, such as a magnetic conduction sheet.
[0025] The utility model has a yet further beneficial effect: the movable contact 3 having
the arc striking structure and the arc striking plate 5 are disposed in such a manner:
two ends of a coil of the electromagnetic trip device 8 are directly connected to
the wiring plate and the static contact 3 respectively, and no support is disposed.
The static contact 3 comprises a contact portion 31 provided with a movable contact
point, an arc striking portion 32 and a yoke portion 33 which are sequentially connected.
The yoke portion 33 is parallel to an axial direction of the coil of the electromagnetic
trip device 8 and parallel to the arc extinguishing grid-plates 2. A V-shaped arc
striking angle is formed between the contact portion 31 and the arc striking portion
32. The contact portion 31 and the arc striking portion 32 are located between the
upper arc striking ribs of the base 1 and the lower arc striking ribs of the housing
cover 6.The arc striking plate 5 comprises a straight section 51, a V-shaped arc striking
section 52 and a limiting section 53 connected to the bimetal sheet 9, which are sequentially
connected. The straight section 51 is parallel to the arc extinguishing grid-plates
2. V-shaped fixing ribs for mounting the arc striking plate 5 are arranged in the
housing. The V-shaped arc-extinguishing section 52 is correspondingly fitted with
the V-shaped fixing ribs. The arc striking plate 5 is connected to the bimetal sheet
9 through the limiting section 53.A supporting protrusion 54 is provided on one side,
corresponding to the limiting section 53, of the V-shaped fixing ribs, so that the
arc striking plate 5 has elastic support, which ensures that the bimetal sheet 9 can
be accurately restored to the original position after being overloaded and bent.
[0026] The utility model further has a beneficial effect in terms of the design of the base
1 and the housing cover 6, as well as the grid-plate 2 and the rear arc extinguishing
structure B mounted thereon. There may be a plurality of manners, where a preferred
manner is as shown in Figs. 4 and 6: the base 1 comprises a plurality of lower fixing
ribs 11, a plurality of lower partitioning ribs 12, a plurality of lower air outlets
14, a plurality of lower arc striking ribs and a plurality of lower fixing grooves
15; the housing cover 6 comprises a plurality of upper fixing ribs 61, a plurality
of upper partitioning ribs 62, a plurality of upper air outlets 64, a plurality of
upper arc striking ribs and a plurality of upper fixing grooves 65. The static connection
of the base 1 and the housing cover 6 should make the lower fixing ribs 11 aligned
to the upper fixing ribs 61 one by one, the lower partitioning ribs 12 docked to the
upper partitioning ribs 62 one by one, the lower air outlets 14docked to the upper
air outlets 64 one by one, and the lower arc striking ribs aligned to the upper arc
striking ribs one by one. A distance between a bottom surface 15d (refer to Fig. 7)
of each lower fixing groove 15 and a bottom surface 65d (refer to Fig. 8) of the corresponding
upper fixing groove 65 is equal to the height H of the arc extinguishing grid-plate
2. It is apparent that the structure of the utility model makes it possible to select
the number of the arc extinguishing grid-plates 2 when assembling the miniature circuit
breaker and it is not necessary to change the structures on the base 1, the housing
cover 6 and the arc extinguishing grid-plates 2 to meet the "multi-positioned" requirements.
The lower partitioning ribs 12 are docked with the upper partitioning ribs 62 one
by one, that is, each lower partitioning rib 12 is docked with the corresponding upper
partitioning rib 62, i.e., each upper partitioning rib 12 is docked with the corresponding
lower partitioning rib 12. The "docked" described herein refers to mutual butting
by which, after the base 1 is statically connected to the housing cover 6, no convection
of high temperature air flows occurs among the air flow passages partitioned by the
docking of the lower partitioning ribs 12 and the upper partitioning ribs 62, thereby
avoiding airflow interference between the two air flow passages. Moreover, the air
outlets of the utility model may include combined air outlets and/or independent air
outlets. As shown in Figs. 1 and 6, a lower air outlet 14 and an upper air outlet
64 of each combined air outlet are a half opening respectively, and the two half openings
are butted to form a complete air outlet. The independent air outlets (not shown in
drawings) are respectively a complete lower air outlet formed in the base 1, and/or
a complete upper air outlet formed in the housing cover 6.Regardless of whether it
is the combined air outlet or the independent air outlet, each air outlet is communicated
with the corresponding air flow passage 13, and the position of each air outlet may
be designed according to the permission of the actual structure.
[0027] Of course, the rear arc extinguishing structure B and the front arc striking structure
C of the miniature circuit breaker of the utility model are not only suitable for
a miniature circuit breaker with multi-positioned arc extinguishing grid-plates, but
also for a miniature circuit breaker adopting an arc extinguishing chamber structure.
According to a second embodiment in Figs. 9-11, no grid-plate fixing structure A is
disposed in the housing of the circuit breaker, but a plurality of arc extinguishing
grid-plates is mounted inside the arc extinguishing chamber 10, and the air extinguishing
chamber 10 is fixedly connected to the housing of the circuit breaker. Air discharge
openings 101 are formed in the rear plate of the arc extinguishing chamber 10. A rear
arc extinguishing structure B is disposed between the air discharge openings 101 of
the arc extinguishing chamber 10 and the air outlets of the housing. The rear arc
extinguishing structure B comprises a plurality of air flow passages disposed between
the air discharge openings 101 of the arc extinguishing chamber 10 and the air outlets
of the housing, such that high temperature air flow in the arc extinguishing chamber
10 passes through the air discharge openings 101 and the plurality of air flow channels,
and is then discharged from the air outlets. Other structures in the circuit breaker
of the embodiment, including the front arc striking structure C, the static contact,
the moving contact, the arc striking plate, etc. are the same as those in the first
embodiment. For example, the front arc extinguishing structure comprises a plurality
of arc striking grooves disposed between an opening in the front side of the arc extinguishing
chamber and the movable contact, which will not be repeated here again. The air flows
flowing out from the grid-plates of the arc extinguishing chamber can be prevented
from interfering with each other by disposing a plurality of air flow passages in
front of the air outlet of the circuit breaker and behind the arc extinguishing chamber,
hot air flows can be prevented from interfering with each other at the air discharge
openings 101, and heat energy can be quickly dissipated, thereby quickly extinguishing
electric arcs, enhancing an arc extinguishing effect of an arc extinguishing system
and a breaking capability of the circuit breaker, and reducing the volume of the arc
extinguishing chamber.
[0028] As shown in Fig. 11, a plurality of arc extinguishing grid-plates is disposed inside
the arc extinguishing chamber 10. An arc extinguishing gap is formed between every
two adjacent arc extinguishing grid-plates. The rear plate of the arc extinguishing
chamber 10 is provided with a plurality of air discharge openings 101. Preferably,
each air discharge opening is in one-to-one correspondence with one arc extinguishing
gap. The plurality of air discharge openings 101 in the rear plate of the arc extinguishing
chamber 10 are disposed on two sides of the rear plate in two columns; the two columns
of air discharge openings 101 are alternately disposed in staggered layers to prevent
hot air flows from interfering with each other at the air discharge openings 101.
[0029] As shown in Figs. 9-10, the housing of the circuit breaker is provided with a plurality
of air outlets each communicated with at least one air flow passage, and each air
flow passage is communicated with the corresponding air discharge opening of the air
extinguishing chamber 10. In particular, the air flow passages of the rear arc extinguishing
structure B include guide passages 131 and exhaust passages 132. Each guide passage
131 is communicated with at least one air discharge opening 101 and at least one exhaust
passage 132. Each exhaust passage 132 is communicated with the corresponding air outlet.
Preferably, the rear arc extinguishing structure B comprises a plurality of guide
passages 131 and a plurality of exhaust passages 132. The number of the exhaust passages
132 is less than the number of the guide passages 131. The plurality of guide passages
131 are in one-to-one correspondence with the plurality of air discharge openings
101 behind the arc extinguishing chamber 10r, to prevent hot air flows from interfering
with each other at the air discharge openings 101. Each exhaust passage 132 is communicated
with at least one guide passage 131 and at least one air outlet. The guide passages
131 are disposed in parallel with the arc extinguishing grid-plates to form a grid-type
heat dissipation structure, and the exhaust passages 132 are disposed in an arc shape.
The plurality of guide passages 131 is formed by partitioning with a plurality of
horizontal partitioning ribs 134. The plurality of horizontal partitioning ribs 134
is disposed in parallel with the arc extinguishing grid-plates to form a grid-type
heat dissipation structure. By means of the guide passages 131, hot gas expanded from
the arc extinguishing chamber 10 flows towards the air outlets, and is then converged
by the guide passages 131, and guided and discharged towards the air outlets, thereby
effectively preventing hot air flows from interfering with each other at the air discharge
openings 101, dissipating heat rapidly, extinguishing the electric arc rapidly and
effectively reducing the volume of the arc extinguishing chamber 10.Of course, this
is a preferred embodiment of the utility model, and the case where only the guide
passages 131 or the exhaust passages 132 are provided may not be excluded. The case
where only the guide passages 131 are provided is as in the first embodiment: i.e.,
the air flow passages of the rear arc extinguishing structure B are a plurality of
guide passages 131 which are disposed between the air discharge openings 101 of the
arc extinguishing chamber 10 and the air outlets of the housing and partitioned by
the arc-shaped partitioning ribs 133. When only the exhaust passages 132 are provided,
that is, the exhaust passages 132 and the air outlets are not partitioned by the arc-shaped
partitioning rib, that is, there is only one large guide passage 131.
[0030] In order to further improve the effects of extinguishing arc, cooling and discharging
high temperature and high pressure air flows of the rear arc extinguishing structure
B, a ratio of a length of each guide passage 131 of the rear arc extinguishing structure
B to a length of the arc extinguishing chamber 10 is 0.2 to 0.5. Due to the size limitation
from the housing of the circuit breaker, the length a of each flow passage 131 and
the length b of the arc extinguishing chamber 10 have a complementary relationship.
Therefore, the length of each guide passage 131 is lengthened by shortening the length
b of the arc extinguishing chamber 10. Since the flow guiding channel 131 also has
the effect of cooling the high-temperature airflow, in particular, due to the structure
of the plurality of guide passages 131 formed by partitioning with the plurality of
horizontal partitioning ribs 134, the horizontal partitioning ribs 134 form a grid-like
heat dissipation structure. Moreover, the heat dissipation structure can obtain better
cooling conditions such as heat dissipation area and heat capacity than the arc extinguishing
grid-plates by optimizing the design, and therefore the cooling effect is particularly
good. Even if the length b of the arc extinguishing chamber 10 is shortened, the cooling
effect may be better. Therefore, the important factors in the optimized design of
the utility model includes the ratio of the length a of each guide passage 131 to
the length b of the arc extinguishing chamber 10.
[0031] In the embodiment as shown in Figs. 9-10, the rear arc extinguishing structure B
comprises a plurality of guide passages 131 and a plurality of exhaust passages 132,
where the number of the exhaust passages 132 is less than that of the guide passages
131. The plurality of guide passages 131 is in one-to-one correspondence with the
plurality of air discharge openings 101 behind the arc extinguishing chamber 10. Four
air outlets are formed in one side of the housing, i.e., a first air outlet 141 close
to the top of a wiring base of a wiring terminal at one side of the housing, a second
air outlet 142 close to the bottom of the wiring base, as well as a third air outlet
143 and a fourth air outlet 144 which are positioned on the sidewall and the bottom
edge of the bottom of one side of the housing respectively. A space between the exhaust
passages 132 and the four air outlets is partitioned by three arc-shaped partitioning
ribs 133 to form four guide passages 131 which are in one-to-one correspondence with
the four air outlets, wherein a ventilation space is preserved at the end part of
the arc-shaped partitioning rib 133 that isolates the third air outlet 143 from the
fourth air outlet 144, such that the third air outlet 143 is communicated with the
fourth air outlet 144.
[0032] The above content is a further detailed description of the utility model made in
conjunction with the specific preferred embodiments, and it is not intended that the
specific embodiments of the utility model are limited to these descriptions. For an
ordinary person skilled in the art to which the present utility model belongs, a number
of simple deductions or substitutions may be made without departing from the spirit
of the utility model should be considered to fall within the protection scope of the
utility model.
1. A miniature circuit breaker, comprising a housing having an air outlet, wherein a
plurality of arc extinguishing grid-plates is mounted in an arc extinguishing chamber
(10); the arc extinguishing chamber(10) is fixedly connected to the housing; an air
discharge opening (101) is formed in a rear plate of the arc extinguishing chamber
(10); a rear arc extinguishing structure is disposed between the air discharge opening
(101)of the arc extinguishing chamber(10) and the air outlet of the housing; the rear
arc extinguishing structure comprises a plurality of air flow passages disposed between
the air discharge opening (101) of the arc extinguishing chamber(10) and the air outlet
of the housing, such that high-temperature air flows in the arc extinguishing chamber
(10) pass through the air discharge opening (101) and the plurality of air flow passages
and are then discharged from the air outlet.
2. The miniature circuit breaker according to claim 1, wherein the air flow passages
of the rear arc extinguishing structure include exhaust passage (132) and a plurality
of guide passages (131); each guide passage (131) is communicated with at least one
air discharge opening (101) and at least one exhaust passage (132); the exhaust passage
(132) is communicated with the air outlet.
3. The miniature circuit breaker according to claim 2, wherein the rear arc extinguishing
structure comprises a plurality of guide passages (131), and the plurality of guide
passages (131) are in one-to-one correspondence with the plurality of air discharge
openings (101) behind the arc extinguishing chamber (10).
4. The miniature circuit breaker according to claim 2, wherein the rear arc extinguishing
structure comprises a plurality of guide passages (131) and a plurality of exhaust
passages (132), where the number of the exhaust passages (132) is less than that of
the guide passages (131); the plurality of guide passages (131) are in one-to-one
correspondence with the plurality of air discharge openings (101) behind the arc extinguishing
chamber (10); each exhaust passage (132) is communicated with at least one guide passage
(131) and at least one air outlet.
5. The miniature circuit breaker according to claim 2, wherein the plurality of guide
passages (131) is formed by partitioning with a plurality of horizontal partitioning
ribs (134); the plurality of horizontal partitioning ribs (134) are disposed in parallel
with the arc extinguishing grid-plates to form a grid-type heat dissipation structure.
6. The miniature circuit breaker according to claim 1, wherein the air flow passages
of the rear arc extinguishing structure are a plurality of guide passages (131) which
are disposed between the air discharging openings (101) of the arc extinguishing chamber
(10) and the air outlets of the housing and partitioned by arc-shaped partitioning
ribs (133).
7. The miniature circuit breaker according to any one of claims 2 to 5, wherein a ratio
of a length of each guide passage (131) of the rear arc extinguishing structure to
a length of the arc extinguishing chamber (10) is 0.2 to 0.5.
8. The miniature circuit breaker according to claim 1, wherein a plurality of arc extinguishing
grid-plates is disposed in the arc extinguishing chamber (10); an arc extinguishing
gap is formed between every two adjacent arc extinguishing grid-plates; a plurality
of air discharge openings (101) is formed in the rear plate of the arc extinguishing
chamber (10); each air discharge opening is in one-to-one correspondence with one
arc extinguishing gap; the plurality of air discharge openings (101) in the rear plate
of the arc extinguishing chamber (10) are disposed on two sides of the rear plate
in two columns; the two columns of air discharge openings (101) are alternately disposed
in staggered levels.
9. The miniature circuit breaker according to claim 4, wherein four air outlets are formed
in one side of the housing, i.e., a first air outlet (141) close to the top of a wiring
base of a wiring terminal at one side of the housing, a second air outlet (142) close
to the bottom of the wiring base, as well as a third air outlet (143) and a fourth
air outlet (144) which are positioned on the sidewall and the bottom edge of the bottom
of one side of the housing respectively; a space between the exhaust passages (132)
and the four air outlets is partitioned by three arc-shaped partitioning ribs (133)
to form four guide passages (131) which are in one-to-one correspondence with the
four air outlets, wherein a ventilation space is preserved at the end part of the
arc-shaped partitioning rib (133) that isolates the third air outlet (143) from the
fourth air outlet (144), such that the third air outlet (143) is communicated with
the fourth air outlet (144).
10. The miniature circuit breaker according to claim 1, further comprising a front arc
extinguishing structure disposed in the housing; the front arc extinguishing structure
comprises a plurality of arc striking grooves which is disposed between an opening
in the front side of the arc extinguishing chamber and a static contact.