CN107293458B

CN107293458B - Small-sized circuit breaker

Info

Publication number: CN107293458B
Application number: CN201610192404.4A
Authority: CN
Inventors: 杨文勇; 杨宇; 司莺歌
Original assignee: Zhejiang Chint Electrics Co Ltd
Current assignee: Zhejiang Chint Electrics Co Ltd
Priority date: 2016-03-30
Filing date: 2016-03-30
Publication date: 2020-08-25
Anticipated expiration: 2036-03-30
Also published as: CN107293458A

Abstract

The miniature circuit breaker comprises a shell provided with an air outlet, a plurality of arc extinguishing grid pieces are arranged in an arc extinguishing chamber, and the arc extinguishing chamber is fixedly connected with the shell; be equipped with the gas vent on the posterior lateral plate of explosion chamber, be equipped with rearmounted arc extinguishing structure between the venthole of the gas vent of explosion chamber and casing, rearmounted arc extinguishing structure including setting up a plurality of airflow channel between the venthole of the gas vent of explosion chamber and casing to discharge from the gas outlet again behind gas vent and a plurality of airflow channel for the high temperature air current in the messenger's explosion chamber. Make the air current between the explosion chamber bars piece each other noninterference after flowing, can prevent effectively that the hot gas flow from the mutual interference of gas vent department, quick bringing the heat out to extinguish electric arc fast, can not only effectively improve the arc extinguishing effect of arc extinguishing system and the breaking capacity of circuit breaker, but also can reduce the volume of explosion chamber.

Description

Small-sized circuit breaker

Technical Field

The invention belongs to the field of low-voltage electric appliances, and particularly relates to a miniature circuit breaker.

Background

The arc extinguishing system of the miniature circuit breaker generally comprises an arc extinguishing chamber consisting of arc extinguishing grids, an arc runner and an arc blowing device for guiding an arc to the arc extinguishing chamber, in particular to a conventionally used miniature circuit breaker with the alternating current of 50Hz, the rated current of 63A and the rated voltage of not more than 400V, wherein the arc extinguishing capability of the arc extinguishing system is related to the breaking capability of the circuit breaker, and the arc extinguishing capability also relates to a plurality of factors. The arc extinguish chamber of a body structure is made earlier with a plurality of arc extinguishing bars to current miniature circuit breaker, adorns the arc extinguish chamber to the circuit breaker again, and some problems exist in this kind of mode: firstly, the arc extinguish chamber with an integrated structure is inconvenient to process and high in manufacturing cost; secondly, the arc extinguishing chamber has a single structure, and the same arc extinguishing chamber is used regardless of the size of the current specification, so that different arc extinguishing requirements of circuit breaker products of different models cannot be met, and the performance of the circuit breaker products is influenced; thirdly, high-temperature air flow in the arc extinguish chamber cannot be exhausted smoothly, and the structure of the arc extinguish chamber causes that an exhaust port behind the arc extinguish chamber cannot be large, so that the arc extinguish effect is influenced.

Meanwhile, the design of the existing circuit breaker arc extinguishing system focuses on the arc extinguishing chamber and the front structures in front of the arc extinguishing chamber, such as arc striking and arc blowing, and the discharge of high-temperature airflow in the arc extinguishing chamber is generally ignored, but experimental research shows that the discharge of the high-temperature airflow is important for the arc extinguishing effect, and the design of the existing circuit breaker arc extinguishing system relates to rear structures such as an exhaust port behind the arc extinguishing chamber, an air outlet on a shell, and an airflow channel between the exhaust port of the arc extinguishing chamber and the air outlet of the shell. The adverse effect of the rear structure is mainly: the mutual interference of the hot air flow sprayed out after the arc passes through the arc extinguish chamber is formed at the air outlet, so that the unsmooth air exhaust of the hot air flow is caused, and the arc extinguish effect of the circuit breaker is influenced. Therefore, people use the existing miniature circuit breaker with an arc extinguish chamber with a large volume, but the arc extinguish chamber is composed of a plurality of arc extinguish grid sheets, so that the structure of the arc extinguish chamber is complicated due to the increase of the volume of the arc extinguish chamber, the processing cost is increased, and the design trend of the miniature circuit breaker is not met. Moreover, the pressure of the hot gas flow is not able to obtain the best arc extinguishing effect and the breaking capacity of the circuit breaker under the condition of the unsmooth exhaust, and the impact damage to the arc extinguishing system including the arc extinguishing chamber is also aggravated, and the strengthening of the impact resistance of the arc extinguishing system also leads to the complication of the arc extinguishing structure and the increase of the manufacturing cost.

Disclosure of Invention

The invention aims to solve the technical problem that the defects that the arc striking and exhausting effects of hot air flow of an exhaust port of an arc extinguish chamber in the prior art are poor and can only be compensated by increasing the volume of the arc extinguish chamber are overcome, and the small circuit breaker is provided.

A miniature circuit breaker comprises a shell provided with an air outlet, a plurality of arc extinguishing grid pieces are arranged in an arc extinguishing chamber 10, and the arc extinguishing chamber 10 is fixedly connected with the shell; be equipped with gas vent 101 on the posterior lateral plate of explosion chamber 10, be equipped with rearmounted arc extinguishing structure between the venthole of gas vent 101 of explosion chamber 10 and casing, rearmounted arc extinguishing structure including setting up a plurality of airflow channel between the venthole of gas vent 101 of explosion chamber 10 and casing to make the high temperature air current in the explosion chamber 10 discharge from the gas outlet again behind gas vent 101 and a plurality of airflow channel.

Preferably, the airflow channel of the rear arc extinguishing structure includes a discharge channel 132 and a plurality of flow guide channels 131, each flow guide channel 131 is communicated with at least one exhaust port 101 and at least one discharge channel 132, and the discharge channel 132 is communicated with an air outlet.

Preferably, the rear arc extinguishing structure includes a plurality of flow guiding channels 131, and the plurality of flow guiding channels 131 are communicated with the plurality of exhaust ports 101 behind the arc extinguishing chamber 10 in a one-to-one correspondence manner.

Preferably, the post-arc extinguishing structure comprises a plurality of flow guide channels 131 and a plurality of discharge channels 132, and the number of the discharge channels 132 is less than that of the flow guide channels 131; the plurality of flow guiding channels 131 are communicated with the plurality of exhaust ports 101 behind the arc extinguish chamber 10 in a one-to-one correspondence manner, and each exhaust channel 132 is communicated with at least one flow guiding channel 131 and at least one air outlet.

Preferably, the plurality of flow guide channels 131 are formed by dividing a plurality of horizontal dividing ribs 134, and the plurality of horizontal dividing ribs 134 and the arc extinguishing grid plate are arranged in parallel to form a grid-shaped heat dissipation structure.

Preferably, the airflow channel of the post-arc extinguishing structure is a plurality of flow guide channels 131 which are arranged between the exhaust port 101 of the arc extinguishing chamber 10 and the air outlet hole of the housing and are separated by arc-shaped dividing ribs 133.

Preferably, the ratio of the length of the flow guide channel 131 of the post-arc extinguishing structure to the length of the arc extinguishing chamber 10 ranges from 0.2 to 0.5.

Preferably, the arc extinguishing chamber 10 in be equipped with a plurality of arc extinguishing bars piece, form the arc extinguishing clearance between the adjacent arc extinguishing bars piece, be equipped with a plurality of gas vents 101 on the posterior lateral plate of arc extinguishing chamber 10, every gas vent respectively with an arc extinguishing clearance one-to-one, a plurality of gas vents 101 on the posterior lateral plate of arc extinguishing chamber 10 divide into two and lay the both sides at the posterior lateral plate, two gas vents 101 are in turn laid by mistake.

Preferably, four air outlets are arranged on one side of the shell, namely a first air outlet 141 close to the top of the wire holder of the wire connecting terminal on one side of the shell, a second air outlet 142 close to the bottom of the wire holder, and a third air outlet 143 and a fourth air outlet 144 which are respectively positioned on the side wall and the bottom edge of the bottom on one side of the shell; four flow guide channels 131 which are in one-to-one correspondence with the four air outlets are formed by three arc-shaped dividing ribs 133 between the drainage channel 132 and the four air outlets, wherein air spaces are reserved at the end parts of the arc-shaped dividing ribs 133 which separate the third air outlet 143 from the fourth air outlet 144 so as to enable the third air outlet 143 to be communicated with the fourth air outlet 144.

Preferably, the arc extinguishing chamber further comprises a front arc ignition structure arranged in the shell, and the front arc ignition structure comprises a plurality of arc ignition grooves arranged between the front opening of the arc extinguishing chamber and the fixed contact.

According to the small circuit breaker, the plurality of airflow channels are additionally arranged in front of the air outlet of the circuit breaker and behind the arc extinguish chamber, so that airflow between the grid pieces of the arc extinguish chamber is not interfered with each other after flowing out, the mutual interference of hot airflow at the air outlet can be effectively prevented, heat is taken out quickly, electric arcs are extinguished quickly, the arc extinguishing effect of an arc extinguishing system and the breaking capacity of the circuit breaker can be effectively improved, and the size of the arc extinguish chamber can be reduced.

Drawings

The invention will be further described with reference to the accompanying drawings and embodiments, the advantages and features of which will become more apparent from the description of the embodiments shown in the drawings, in which:

fig. 1 is a perspective view showing an internal overall structure of a small circuit breaker of the present invention showing a fixing structure of arc chute pieces 2 to a base 1.

Fig. 2 is a schematic perspective view of a grid 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 schematic plan view of fig. 1.

Fig. 4 is a schematic plan view of fig. 2.

Fig. 5 is a perspective view of the arc chute 2 in the embodiment shown in fig. 1.

Fig. 6 is a perspective view of the cover 6.

Fig. 7 is a partially enlarged view E of fig. 2.

Fig. 8 is a partial enlarged view F of fig. 6.

Fig. 9-10 illustrate another embodiment of the present invention.

Fig. 11 is a perspective view of the arc chute of fig. 9.

Detailed Description

As can be seen from the perspective view of the whole internal structure of the miniature circuit breaker shown in fig. 1 and the perspective view of the case cover 6 shown in fig. 6, the miniature circuit breaker with the multiple placement type arc chute plates of the present invention includes a case body formed by the base 1 and the case cover 6, the base 1 and the case cover 6 can be statically connected by any known method (such as screws, clamping, etc.), a fixed contact 3 and a movable contact 4 are disposed in a cavity formed between the base 1 and the case cover 6, and the handle drives the movable contact 4 to swing to contact with and separate from the fixed contact 3 through the operating mechanism 7 to realize the on-off of the circuit.

The circuit breaker belongs to products with different current specifications according to the requirements of users, and the requirements on arc extinguishing systems are different, and the miniature circuit breaker with the multiple arc extinguishing grid pieces is characterized in that a grid piece fixing structure A for fixing the arc extinguishing grid pieces 2 is arranged on a shell, and the arc extinguishing grid pieces 2 are directly and statically connected with the shell through the grid piece fixing structure A, so that gaps 2a communicated with air outlets on the shell are formed between every two adjacent arc extinguishing grid pieces 2. The arc extinguishing grid plates with different numbers can be placed in different current specifications by arranging the grid plate fixing structure A, the arc extinguishing chamber does not need to be made into an integral type, the processing is convenient, and the structure of a product is optimized. The arc-extinguishing grids 2 are directly and statically connected with the base 1 and the shell cover 6 through grid fixing structures A respectively, and the static connection enables a plurality of gaps 2a to be formed between every two adjacent arc-extinguishing grids 2. The 'multiple placing type' mentioned here means that the number of the arc-extinguishing bars 2 can be determined according to different arc-extinguishing requirements of different types of circuit breaker products, and the arc-extinguishing bars 2 can be directly fixed on the base 1 and the cover 6 by respectively being directly and statically connected with the base 1 and the cover 6, without adopting the existing arc-extinguishing chamber structure that a plurality of arc-extinguishing bars are fixedly connected together through the plate-wall element constituting the arc-extinguishing chamber, and without adjusting the shell. Obviously, realize the pluralism of the quantity of arc extinguishing bars piece 2, its key lies in adopting the arc extinguishing bars piece 2 and the bars piece fixed knot structure A of many units formula of placing, and its beneficial effect includes: the problem that the arc extinguishing chamber is too large or too small can be effectively overcome, so that the requirement of miniaturization is met, and meanwhile, the excellent arc extinguishing effect is ensured.

In order to further improve the arc extinguishing effect of the invention, the miniature circuit breaker further comprises a rear arc extinguishing structure B and a front arc striking structure C which are arranged in the shell, wherein the rear arc extinguishing structure B comprises a plurality of air flow channels 13a, 13B and 13C which are arranged between the gap 2a between the arc extinguishing grid plates 2 on the grid plate fixing structure A and the air outlet, so that high-temperature air flow in the gap 2a is guided by the air flow channels 13a, 13B and 13C and then is discharged from the air outlet. The front arc striking structure C comprises a plurality of arc striking grooves 16 arranged between the arc extinguishing grid plates 2 on the grid plate fixing structure A and the fixed contact. As shown in fig. 1 to 4, the miniature circuit breaker of the present embodiment is further provided with an instantaneous trip including an electromagnetic trip device 8 and an overload trip including a bimetal 9 in a housing; the striker of the electromagnetic trip device 8 is arranged corresponding to the latch of the operating mechanism, and the bimetallic strip 9 is arranged corresponding to a transmission rod (not shown in the figure) extending from the latch. When electricity leaks, a firing pin of the electromagnetic tripping device 8 is popped out to impact a lock catch of the operating mechanism to trip the circuit breaker; when the circuit is overloaded, the bimetallic strip bends to pull the lock catch through the transmission rod so as to release the circuit breaker. A grid fixing structure A for fixing the arc extinguishing grid 2 is arranged below the electromagnetic tripping device 8, and a rear arc extinguishing structure B and a front arc striking structure C are respectively arranged on two sides of the grid fixing structure A; a static contact 3 with an arc striking structure and an arc striking plate 5 with a V-shaped arc striking angle are respectively arranged above and below one side of the grid fixing structure A close to the front arc striking structure C; the static contact 3 is connected with a coil of the electromagnetic tripping device 8, and the arc striking plate 5 is connected with the bimetallic strip 9. Through the setting of each striking structure, can be with the quick arc to arc extinguishing bars piece 2 of leading to through rearmounted arc extinguishing structure B and gas outlet with high-temperature gas quick discharge, can effectively improve arc extinguishing effect and breaking capacity.

Another advantageous feature of the miniature circuit breaker of the present invention is related to the grid fixing structure a, which can be provided in various ways, one preferred way is shown in fig. 2 and 4: the grid fixing structure a comprises a plurality of lower fixing grooves 15 arranged on the base 1 and a plurality of upper fixing grooves 65 (see fig. 6 and 8) arranged on the shell cover 6, wherein the lower edges 21 (see fig. 5) of the arc-extinguishing grids 2 are respectively embedded and fixed in the lower fixing grooves 15, the upper edges 22 (see fig. 5) of the arc-extinguishing grids 2 are respectively embedded and fixed in the upper fixing grooves 65, and the arc-extinguishing grids 2 are respectively directly and statically connected with the base 1 and the shell cover 6 through the embedded and fixed structure. The lower fixing groove 15 and the upper fixing groove 65 may be constructed in various ways, and a preferred way is as shown in fig. 2 to 8: a plurality of lower fixing ribs 11 (see fig. 7) are arranged on the base 1, each lower fixing groove 15 of the grid fixing structure a shown in fig. 2 and 4 is formed by an interval between two adjacent lower fixing ribs 11, and the height of each lower fixing rib 11 is far less than the height H of each arc-extinguishing grid 2 (see fig. 5); referring to fig. 6, the housing cover 6 is provided with a plurality of upper fixing ribs 61, each upper fixing groove 65 of the grid fixing structure a is formed by the interval between two adjacent upper fixing ribs 61, and the height of the upper fixing rib 61 is far less than the height H of the arc extinguishing grid 2 (see fig. 5). In order to ensure that the static connection between the arc chute 2 and the lower and

upper fixing grooves

15, 65 does not loosen under the impact of the high-temperature gas flow, and at the same time ensure that the gap 2a has a sufficient residual height (which is equal to the height H of the arc chute 2 minus the height of the lower and upper edges 21, 22), the dimensional fit between the arc chute 2 and the lower and

upper fixing grooves

15, 65 has to be optimized in a number of specific ways, one preferred way being: the width D1 (see fig. 7) of the lower fixing groove 15 of the grid fixing structure a is equal to the thickness D (see fig. 5) of the arc chute 2, the length of the lower fixing groove 15 is equal to the length b (see fig. 5) of the arc chute 2, and the depth H1 (see fig. 7) of the lower fixing groove 15 is far less than the height H of the arc chute 2. The width D6 (see fig. 8) of the upper fixing groove 65 of the grid fixing structure a is equal to the thickness D of the arc-extinguishing grid 2, the length of the upper fixing groove 65 is equal to the length b of the arc-extinguishing grid 2, and the depth H6 (see fig. 8) of the lower fixing groove 65 is far less than the height H of the arc-extinguishing grid 2. As can be seen from the embodiment shown in fig. 2 and 7, the height of the lower fixing rib 11 is equal to the depth h1 (see fig. 7) of the lower fixing groove 15. As can be seen from the embodiment shown in fig. 6 and 8, the height of the upper fixing rib 61 is equal to the depth h6 of the upper fixing groove 65 (see fig. 8); however, in the case of the grid fixing structures a that can be used in practice, they may not be exactly equal, but if the above-mentioned far smaller values are satisfied, the largest possible residual height of the gap 2a can be obtained while ensuring that the static coupling does not loosen, since the larger the residual height is, the better the arc extinguishing effect of the arc extinguishing grid 2 is, and the faster the high-temperature air flow in the gap 2a flows to the rear arc extinguishing structure B. For example, the depth H6 of the lower fixing groove 65 may be less than one sixth of the height H of the arc chute 2, the depth H6 of the upper fixing groove 15 may be less than one sixth of the height H of the arc chute 2, the height of the upper fixing rib 61 may be less than one sixth of the height H of the arc chute 2, and the height of the lower fixing rib 11 may be less than one sixth of the height H of the arc chute 2.

The miniature circuit breaker with the multiple arc-extinguishing bars has the beneficial characteristics that the miniature circuit breaker with the multiple arc-extinguishing bars further comprises a rear arc-extinguishing structure B arranged in the shell, and the rear arc-extinguishing structure B comprises a plurality of

air flow channels

13a, 13B and 13c arranged between the gap 2a between the arc-extinguishing bars 2 on the bar fixing structure A and the air outlet, so that high-temperature air flow in the gap 2a is guided by the

air flow channels

13a, 13B and 13c and then is exhausted from the air outlet. The post-arc extinguishing structure B can be structured in various ways, and a preferred way is shown in fig. 2 and 4: the base 1 on be provided with many and cut apart muscle 12 down, the cap 6 on be provided with many and cut apart muscle 62 (refer to fig. 6) on, cut apart muscle 12 down and cut apart muscle 62 butt joint on with, separate into a plurality of air

current channels

13a, 13B and 13c of rearmounted arc extinguishing structure B with the space between base 1 and the cap 6, every air

current channel

13a, 13B or 13c link up with clearance 2a and at least one gas outlet of at least one arc extinguishing bars piece 2 respectively. The beneficial effects of the rear arc extinguishing structure B are as follows: firstly, the arc is cut into arc sections by the gaps 2a between the arc-extinguishing grid pieces 2, each arc section is rapidly extinguished in each gap 2a, and high-temperature and high-pressure airflow is formed in the gap 2a, and because each gap 2a of the arc-extinguishing grid piece 2 is directly communicated with the

airflow channels

13a, 13B and 13c of the rear arc-extinguishing structure B, and the airflow channels can improve a larger negative pressure space, the high-temperature and high-pressure airflow in the gap 2a can be timely and rapidly guided into the

airflow channels

13a, 13B and 13c, and the arc-extinguishing capacity of the arc-extinguishing grid piece 2 can be effectively improved. Second, since the high-temperature air flows flowing out of the gap 2a flow to the plurality of

air outlets

14 and 64 from the plurality of

air flow passages

13a, 13b, and 13c, respectively, and then are discharged out of the base 1 of the circuit breaker, the high-temperature air flows do not interfere with each other during the flow and discharge process, and can be smoothly and rapidly 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 butting and separating the plurality of lower dividing ribs 12 and the plurality of upper dividing ribs 62, and the dividing ribs also have the heat dissipation effect, the cooling of the high-temperature air flow can be effectively accelerated by increasing the dividing ribs. Fourthly, as the rear arc extinguishing structure B has the characteristics of smooth and quick exhaust, the impact of airflow can be effectively relieved, and the structure including the arc extinguishing grid pieces 2 is prevented from being damaged by impact. Therefore, the invention can effectively overcome the following defects of the existing arc extinguish chamber structure: because the gas vent at explosion chamber rear is narrow, the high temperature high pressure air current in the explosion chamber is difficult for following the gas vent and discharging, and still influencing excretory mutual interference at the gas vent, lead to difficult excretory high temperature high pressure air current who remains in the explosion chamber to have serious threat to the arc extinguishing effect, if lead to electric arc to restrike etc. repeatedly.

In order to further improve the effect of discharging high-temperature and high-pressure air flow of the post-arc extinguishing structure B, a preferred structure scheme is as shown in fig. 3 and 4, a plurality of air outlets and a plurality of

air flow channels

13a, 13B and 13c are arranged in the housing; each

air flow channel

13a, 13b, 13c is connected to the gap 2a of at least one arc chute 2 and to at least one air outlet. Specifically, four air outlets are arranged on one side of the shell, namely a first air outlet 141 close to the top of the wire holder of the wiring terminal on one side of the shell, a second air outlet 142 close to the bottom of the wire holder, and a third air outlet 143 and a fourth air outlet 144 which are respectively positioned on the side wall and the bottom edge of the bottom on one side of the shell; the first separating rib 121 completely separates the first air outlet 141 and the second air outlet 142 from the third air outlet 143 and the fourth air outlet 144 to form an upper air flow channel 13c and a lower air flow channel, and the first air outlet 141 and the second air outlet 142 are communicated with more than half of gaps 2a between the arc-extinguishing grid pieces 2; the second separating rib 122 separates the third air outlet 143 from the fourth air outlet 144 to guide high-temperature air flow, and separates the lower air flow channel to form a first lower air flow channel 13a and a second lower air flow channel 13b, one end of the second separating rib 122 is connected with the gap 2a between the arc-extinguishing grid plates 2, the other end extends to the space between the third air outlet 143 and the fourth air outlet 144, and an air-passing space is reserved to enable the third air outlet 143 and the fourth air outlet 144 to be communicated. It is apparent that this structure enables the high-temperature and high-pressure air flow to be discharged from the four air outlets through the first lower air flow path 13a, the second lower air flow path 13b, and the upper air flow path 13c, to further improve the effect of smooth, quick, and disturbance prevention of discharge.

Still another beneficial feature of the present invention is that the arc extinguishing device further comprises a front arc striking structure C disposed in the housing, as shown in fig. 3, the front arc striking structure C includes a plurality of arc striking grooves 16 disposed between the arc extinguishing grid 2 and the stationary contact on the grid fixing structure a. The arc striking grooves 16 correspond to the gaps 2a between the arc extinguishing grid pieces 2 one by one. Specifically, a plurality of upper arc striking ribs are arranged on the base 1, a plurality of lower arc striking ribs are correspondingly arranged on the shell cover 6, and a space for contacting the static contact 3 with the moving contact 4 is formed between the upper arc striking ribs and the lower arc striking ribs after the base 1 and the shell cover 6 are oppositely connected; the static contact 3 is arranged between the upper arc striking rib and the lower arc striking rib, and the moving contact 4 swings between the upper arc striking rib and the lower arc striking rib to the direction close to the arc extinguishing grid piece 2 and is contacted with the static contact 3. Through the arc striking grooves 16, the electric arcs generated by the moving contact and the static contact are respectively and quickly led to the gaps 2a among the arc extinguishing grid pieces 2, so that an airflow channel of the electric arcs is improved, the arc extinguishing capability of the circuit breaker is improved, and elements such as magnetic conductive pieces can be assembled sparingly.

The invention has the following beneficial characteristics that the static contact 3 and the arc striking plate 5 with the arc striking structure are arranged: the two ends of the coil of the electromagnetic tripping device 8 are respectively and directly connected with the wiring board and the static contact 3, a bracket is not required to be arranged, the static contact 3 comprises a contact part 31, an arc striking part 32 and a yoke part 33 which are sequentially connected, the contact part 31, the arc striking part 32 and the yoke part 33 are provided with static contacts, the yoke part 33 is parallel to the axial direction of the coil of the electromagnetic tripping device 8 and is parallel to the arc extinguishing grid plate 2, and a V-shaped arc striking angle is formed between the contact part 31 and the arc striking part 32; the contact part 31 and the arc striking part 32 are located between the upper arc striking rib of the base 1 and the lower arc striking rib of the 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 with the bimetallic strip 9, which are connected in sequence; the straight section 51 is parallel to the arc extinguishing grid piece 2, a V-shaped fixing rib for installing the arc striking plate 5 is arranged in the shell, the V-shaped arc striking section 52 is correspondingly clamped with the V-shaped fixing rib, the arc striking plate 5 is connected with the bimetallic strip 9 through the limiting section 53, and a supporting bulge 54 is arranged on one side of the V-shaped fixing rib corresponding to the limiting section 53, so that the arc striking plate 5 has elastic support, and the bimetallic strip 9 can be accurately restored to the original position after being bent in an overload mode.

The invention also has an advantageous feature in relation to the design of the base 1 and the cover 6 and the grid fixing structure a and the post arc extinguishing structure B thereon, which can be implemented in various ways, one preferred way being shown in fig. 1-4 and 6: the base 1 comprises a plurality of lower fixing ribs 11, a plurality of lower dividing ribs 12, a plurality of lower air outlets 14, a plurality of lower arc-leading ribs and a plurality of lower fixing grooves 15, and the shell cover 6 comprises a plurality of upper fixing ribs 61, a plurality of upper dividing ribs 62, a plurality of upper air outlets 64, a plurality of upper arc-leading ribs and a plurality of upper fixing grooves 65; the static connection between the base 1 and the cover 6 is such that each lower fixing rib 11 is opposite to each upper fixing rib 61, each lower dividing rib 12 is opposite to each upper dividing rib 62, each lower air outlet 14 is opposite to each upper air outlet 64, each lower arc striking rib is opposite to each upper arc striking rib, and the distance between the bottom surface 15d (see fig. 7) of the lower fixing groove 15 and the bottom surface 65d (see fig. 8) of the upper fixing groove 65 is equal to the height H of the arc extinguishing grid piece 2. Obviously, the structure of the invention enables the number of arc-extinguishing bars 2 to be selected and determined when the miniature circuit breaker is assembled, and the structures on the base 1, the shell cover 6 and the arc-extinguishing bars 2 do not need to be changed so as to meet the requirement of multiple placement. Each lower division rib 12 is in one-to-one butt joint with each upper division rib 62, that is, each lower division rib 12 is in butt joint with the corresponding upper division rib 62, that is, each upper division rib 62 is in butt joint with the corresponding lower division rib 12. The "butt joint" described here means a mutual abutting joint, by which, after the base 1 and the cover 6 are statically coupled, the lower split rib 12 and the upper split rib 62 are abutted together to realize separation, so that high-temperature air flow is not convected between the air flow passages, thereby avoiding air flow interference between the two air flow passages. Moreover, the air outlets of the present invention may include a combined air outlet and/or an independent air outlet; as shown in fig. 1 and 6, the lower air outlet 14 and the upper air outlet 64 of the combined air outlet are respectively half-ports, and the two half-ports are combined into a complete air outlet in a butt joint manner. The independent air outlets (not shown in the figure) are respectively a complete lower air outlet arranged on the base 1 and/or a complete upper air outlet arranged on the shell cover 6. Regardless of the combination air outlet or the independent air outlet, each air outlet is communicated with the air flow channel 13, and the positions of the air outlets can be designed according to the permission of the actual structure.

Of course, the rear arc extinguishing structure B and the front arc striking structure C of the miniature circuit breaker are not only suitable for the miniature circuit breaker with a multi-unit placing type arc extinguishing grid piece, but also suitable for the miniature circuit breaker adopting an arc extinguishing chamber structure. As in the second embodiment of fig. 9-11, the grid fixing structure a is not provided in the housing of the circuit breaker, the arc extinguishing grids 10 are installed in the arc extinguishing chamber 10, and the arc extinguishing chamber 10 is fixedly connected with the housing of the circuit breaker; be equipped with gas vent 101 on the posterior lateral plate of explosion chamber 10, be equipped with rearmounted arc extinguishing structure B between the venthole of gas vent 101 of explosion chamber 10 and casing, rearmounted arc extinguishing structure B including setting up a plurality of airflow channel between the venthole of gas vent 101 of explosion chamber 10 and casing to discharge from the gas outlet again behind gas vent 101 and a plurality of airflow channel of high temperature air current in the messenger explosion chamber 10. Other structures in the circuit breaker of this embodiment, including leading striking structure C, the static contact, the moving contact, striking plate etc. are the same as in the first embodiment, for example leading striking structure include setting up a plurality of arc ignition grooves between explosion chamber front side opening and static contact, and again do not describe in detail. Set up a plurality of airflow channels through increasing in circuit breaker gas outlet the place ahead and explosion chamber rear for each other noninterference after the air current between the explosion chamber bars piece flows, can prevent effectively that the hot gas flow from at the mutual interference of gas vent 101 department, quick bringing the heat out, thereby extinguish electric arc fast, can not only effectively improve the arc extinguishing effect of arc extinguishing system and the breaking capacity of circuit breaker, but also can reduce the volume of explosion chamber.

As shown in fig. 11, a plurality of arc-extinguishing bars are disposed in the arc-extinguishing chamber 10, arc-extinguishing gaps are formed between adjacent arc-extinguishing bars, and a plurality of exhaust ports 101 are disposed on a rear side plate of the arc-extinguishing chamber 10. Preferably, each exhaust port corresponds to one arc extinguishing gap, the exhaust ports 101 on the rear side plate of the arc extinguishing chamber 10 are divided into two rows and arranged on two sides of the rear side plate, and the two rows of exhaust ports 101 are alternately arranged in a staggered manner, so that mutual interference of hot air flow at the exhaust ports 101 is avoided.

As shown in fig. 9 to 10, a plurality of air outlets are provided on the housing of the circuit breaker, each air outlet communicating with at least one air flow channel, each air flow channel communicating with an exhaust port of the arc chute 10. Specifically, the airflow channel of the post-arc extinguishing structure B of the present embodiment includes a flow guiding channel 131 and a discharge channel 132, each flow guiding channel 131 is communicated with at least one exhaust port 101 and at least one discharge channel 132, and the discharge channel 132 is communicated with an air outlet. Preferably, the post-arc extinguishing structure B includes a plurality of flow guiding channels 131 and a plurality of drainage channels 132, and the number of the drainage channels 132 is less than the number of the flow guiding channels 131; the plurality of flow guide channels 131 are communicated with the plurality of exhaust ports 101 behind the arc extinguish chamber 10 in a one-to-one correspondence manner, so that the mutual interference of hot air flow at the exhaust ports 101 is avoided; each drainage channel 132 is connected to at least one flow guide channel 131 and to at least one air outlet. The flow guiding channels 131 and the arc extinguishing grids are arranged in parallel to form a grid-shaped heat dissipation structure, and the drainage channels 132 are arranged in an arc shape. The plurality of flow guide channels 131 are formed by dividing a plurality of horizontal dividing ribs 134, and the plurality of horizontal dividing ribs 134 and the arc extinguishing grid plate are arranged in parallel to form a grid-shaped heat dissipation structure. Through the setting of water conservancy diversion passageway 131, the hot gas that expands out in from explosion chamber 10 flows to the gas outlet direction respectively, and rethread water conservancy diversion passageway 131 converges and gets rid of to the gas outlet direction water conservancy diversion, can effectively prevent the mutual interference of hot gas flow in gas vent 101 department, and the heat is taken out fast to extinguish electric arc fast, effectively reduce the volume of explosion chamber 10 moreover. Of course, this is a preferred embodiment of the present invention, and it is not excluded that only the flow guide passage 131 or the drainage passage 132 is provided. The case of only providing the flow guiding channel 131 is the first embodiment, that is, the gas flow channel of the post-arc extinguishing structure B is a plurality of flow guiding channels 131 which are arranged between the exhaust port 101 of the arc extinguishing chamber 10 and the air outlet hole of the housing and are separated by the arc-shaped dividing rib 133. In the case where only the drainage channel 132 is provided, i.e., the drainage channel 132 and the air outlet are not separated by the arc-shaped dividing rib, there are only 1 large flow guide channel 131.

In order to further improve the effects of arc extinguishing, temperature reduction and high-temperature and high-pressure air flow discharge of the post-arc extinguishing structure B, the ratio of the length a of the flow guide channel 131 of the post-arc extinguishing structure B to the length B of the arc extinguishing chamber 10 ranges from 0.2 to 0.5. As defined by the dimensions of the housing of the circuit breaker, the length a of the current guiding channel 131 and the length b of the arc chute 10 have a complementary relationship, the lengthening of the length a of the flow guiding channel 131 is obtained by shortening the length b of the arc chute 10, because the diversion channel 131 also has the effect of cooling the high-temperature air flow, especially because the structure of the diversion channel 131 formed by the division of the horizontal division ribs 134 is adopted, each horizontal division rib 134 forms a grid-shaped heat dissipation structure, and the heat dissipation structure can obtain better cooling conditions (such as heat dissipation area and heat capacity) than the arc extinguishing grid plate through optimized design, so the cooling effect is particularly good, even if the length b of the arc chute 10 is shortened, the cooling effect may be better, and therefore, the important factor of the optimized design of the present invention includes the ratio of the length a of the flow guide channel 131 to the length b of the arc chute 10.

In the embodiment shown in fig. 9 to 10, the post-arc extinguishing structure B includes a plurality of flow guiding channels 131 and a plurality of discharge channels 132, and the number of the discharge channels 132 is less than that of the flow guiding channels 131; the plurality of flow guide channels 131 are communicated with the plurality of exhaust ports 101 behind the arc extinguish chamber 10 in a one-to-one correspondence manner; four air outlets are arranged on one side of the shell, namely a first air outlet 141 close to the top of the wire holder of the wire connecting terminal on one side of the shell, a second air outlet 142 close to the bottom of the wire holder, and a third air outlet 143 and a fourth air outlet 144 which are respectively positioned on the side wall and the bottom edge of the bottom on one side of the shell. Four flow guide channels 131 which are in one-to-one correspondence with the four air outlets are formed by three arc-shaped dividing ribs 133 between the drainage channel 132 and the four air outlets, wherein air spaces are reserved at the end parts of the arc-shaped dividing ribs 133 which separate the third air outlet 143 from the fourth air outlet 144 so as to enable the third air outlet 143 to be communicated with the fourth air outlet 144.

The foregoing is a more detailed description of the invention in connection with specific preferred embodiments and it is not intended that the invention be limited to these specific details. For those skilled in the art to which the invention pertains, several simple deductions or substitutions can be made without departing from the spirit of the invention, and all shall be considered as belonging to the protection scope of the invention.

Claims

1. A miniature circuit breaker, includes the casing that is equipped with the gas outlet, its characterized in that: the arc extinguishing grid pieces are arranged in the arc extinguishing chamber (10), and the arc extinguishing chamber (10) is fixedly connected with the shell; the rear side plate of the arc extinguish chamber (10) is provided with an exhaust port (101), a rear arc extinguish structure is arranged between the exhaust port (101) of the arc extinguish chamber (10) and an air outlet of the shell, and the rear arc extinguish structure comprises a plurality of airflow channels arranged between the exhaust port (101) of the arc extinguish chamber (10) and the air outlet of the shell, so that high-temperature airflow in the arc extinguish chamber (10) is exhausted from the air outlet after passing through the exhaust port (101) and the airflow channels;

the airflow channel of the rear arc extinguishing structure comprises a plurality of drainage channels (132) and a plurality of flow guide channels (131), the flow guide channels (131) are communicated with a plurality of exhaust ports (101) behind the arc extinguishing chamber (10) in a one-to-one correspondence manner, the flow guide channels (131) are formed by dividing a plurality of horizontal dividing ribs (134), the horizontal dividing ribs (134) and the arc extinguishing grid sheet are arranged in parallel to form a grid-shaped heat dissipation structure, and the ratio range of the length of the flow guide channels (131) to the length of the arc extinguishing chamber (10) is 0.2-0.5; the number of the drainage channels (132) is less than that of the flow guide channels (131), and each drainage channel (132) is communicated with at least one flow guide channel (131) and at least one air outlet.

2. A miniature circuit breaker according to claim 1, wherein: arc extinguishing chamber (10) in be equipped with a plurality of arc extinguishing bars piece, form the arc extinguishing clearance between adjacent arc extinguishing bars piece, be equipped with a plurality of gas vents (101) on the posterior lateral plate of arc extinguishing chamber (10), every gas vent respectively with an arc extinguishing clearance one-to-one, a plurality of gas vents (101) on the posterior lateral plate of arc extinguishing chamber (10) divide into two and lay the both sides at the posterior lateral plate, two gas vents (101) are in turn laid in staggered floor.

3. A miniature circuit breaker according to claim 1, wherein: four air outlets are arranged on one side of the shell, namely a first air outlet (141) close to the top of the wire holder of the wiring terminal on one side of the shell, a second air outlet (142) close to the bottom of the wire holder, and a third air outlet (143) and a fourth air outlet (144) which are respectively positioned on the side wall and the bottom edge of the bottom on one side of the shell; four flow guide channels (131) which are in one-to-one correspondence with the four air outlets are formed between the drainage channel (132) and the four air outlets through three arc-shaped dividing ribs (133), wherein air communicating spaces are reserved at the end parts of the arc-shaped dividing ribs (133) which separate the third air outlet (143) from the fourth air outlet (144) to enable the third air outlet (143) to be communicated with the fourth air outlet (144).

4. A miniature circuit breaker according to claim 1, wherein: the arc extinguishing chamber is characterized by further comprising a front arc ignition structure arranged in the shell, and the front arc ignition structure comprises a plurality of arc ignition grooves arranged between the front opening of the arc extinguishing chamber and the fixed contact.