CN208722819U - Breaker of plastic casing - Google Patents

Abstract

A kind of breaker of plastic casing, including shell, the arc-chutes of the big shaft that is pivotally mounted to enclosure interior, the contact system for being installed on enclosure interior and the electric arc for absorbing contact system generation, the contact system includes the movable touch knife being pivotally mounted in big shaft and is installed on enclosure interior and quiescent contacting knife that movable touch knife is oppositely arranged, and the pivotal connection of movable touch knife and big shaft is located at one end of the contact of separate quiescent contacting knife in big shaft.The utility model breaker of plastic casing, movable touch knife and the pivotal connection of big shaft are no longer set to the spindle central position of big shaft, and it is provided at one end of the contact in big shaft far from quiescent contacting knife, the center of rotation of movable touch knife is more posteriorly, it is longer to rotate the arm of force, when short circuit current flows through contact knife, the reprimand that contact knife can be reached when smaller electric current flows through opens effect, and denounce opening away from bigger after opening, it can quick pull-up electric arc, product current limiting capacity and disjunction effect are improved, to improve the breaking capacity of breaker.

Description

Breaker of plastic casing

Technical field

The utility model relates to Low Voltage Electrical Apparatus, in particular to a kind of breaker of plastic casing.

Background technique

With the continuous development of breaker of plastic casing, miniaturization, breaking capacity height, current specification have become present market comprehensively Upper main product also becomes the target that all big enterprises competitively chase simultaneously.Low-voltage circuit breaker is main first device of low voltage electrical equipment Part.As market competition is aggravated, client is more professional to Selection of Circuit Breakers, high breaking, high target is not being pursued, instead to product Cost-effectiveness requirement it is higher, force and need to develop the product that small in size, at low cost, performance parameters meet normal use.

Since the dynamic and static contact (i.e. upper and lower contact) of breaker can generate electric arc when separated, dynamic/static contact separates one As all be by buckle releaser promotion promote the mechanism action of breaker to cut-off circuit to reach separately dynamic and static contact.But mechanism The band continuous mechanical movement of movable touch knife one needs certain time, when breaker passes through short circuit current, does not allow completely also in mechanism When dynamic and static contact separates, breaker tolerance does not live high current and damages.It is unable to reach expected high breaking capacity index.

Summary of the invention

The purpose of the utility model is to overcome the defect of the prior art, a kind of breaker of plastic casing is provided, movable touch knife and big The pivotal connection of shaft is not provided in the spindle central position of big shaft, and is provided at the contact in big shaft far from quiescent contacting knife One end, the center of rotation of movable touch knife rearward, rotation the arm of force it is longer, the reprimand that contact knife can be reached when smaller electric current flows through is opened Effect, and reprimand open after open away from bigger, can quick pull-up electric arc, improve product current limiting capacity and disjunction effect.

To achieve the above object, the utility model adopts the technical scheme that

A kind of breaker of plastic casing including shell, the big shaft 1 that is pivotally mounted to enclosure interior, is installed on enclosure interior The arc-chutes 3 of contact system and the electric arc for absorbing contact system generation, the contact system include being pivotally mounted to turn greatly Movable touch knife 2 on axis 1 and it is installed on enclosure interior and quiescent contacting knife 4 that movable touch knife 2 is oppositely arranged, the pivot of movable touch knife 2 and big shaft 1 Turn the one end for the contact that junction is located in big shaft 1 far from quiescent contacting knife 4.

It further, further include phase insulation box 5 for completely cutting off each pole conducting system, installation in each phase insulation box 5 There are the arc-chutes 3 and contact system of a pole conducting system, arc-chutes 3 are installed on the top of phase insulation box 5, and the one of quiescent contacting knife 4 It holds and passes through the bottom that the lower section for stretching to arc-chutes 3 is installed on phase insulation box 5 from the side of phase insulation box 5, big shaft 1 is located at The other side of phase insulation box 5, the movable touch knife 2 in big shaft 1 is passed through from the other side of phase insulation box 5 stretches to arc-chutes 3 Enter the top in nock c positioned at contact knife 4 to be oppositely arranged with quiescent contacting knife 4；One end that contact is arranged in the quiescent contacting knife 4 is equipped with U-shaped section Towards the side of phase insulation box 5, the contact of quiescent contacting knife 4 is set to U-shaped section 41 and is located at upside the U-shaped opening of 41, U type sections 41 The upper surface of flat segments 411.

Further, the movable touch knife 2 is located at the top of big shaft 1 with the pivotal connection of big shaft 1, is located remotely from stationary contact The side of the contact of knife 4.

Further, the movable touch knife 2 passes through reset spring 6 and is pivotally connected axis 9 and is installed in big shaft 1；Movable touch knife 2 One end be equipped with be pivotally connected axis 9 installation cooperation mounting hole 201, big 1 top of shaft be equipped with be pivotally connected axis 9 both ends pacify What assembly was closed is pivotally connected slot 101, is pivotally connected axis 9 across both ends after reset spring 6 and mounting hole 201 and is pivotally connected slot 101 installations are fixed.

Further, the big shaft 1 is cylindrical type shaft, and the top of big shaft 1 is offered for installing movable touch knife 2, answering Position spring 6 and the construction opening 11 for being pivotally connected axis 9, construction opening 11 include 111 He of the first mounting groove for accommodating reset spring 6 The movable touch knife that the bottom notch of first mounting groove 111 is equipped with the other end for installing movable touch knife 2 stretches out slot 112, is pivotally connected Slot 101 is set to the two sides side wall of the first mounting groove 111.

Further, the slot 101 that is pivotally connected is tip-angled shape gap slot, and the open at one end for being pivotally connected slot 101 extends to The sidewall edge of construction opening 11, the tip one end for being pivotally connected slot 101 extend to big contact of the shaft 1 far from quiescent contacting knife 4 Side.

Further, round axis body 15 of the big shaft 1 including middle part is used to pacify with what distribution on round axis body 15 was arranged The columned mounting post 16 of movable touch knife 2 is filled, construction opening 11 is set in mounting post 16, and the lateral wall of round axis body 15 is adjacent Protrusion, which is equipped with, between two mounting posts 16 is used for annular projection 151.

Further, the reset spring 6 is torsion spring, is connected between two torsional springs by linkage section 61, two torsional springs point Not Wei Yu movable touch knife 2 two sides, each torsional spring include middle part torsional spring ontology 62 and torsional spring ontology 62 extend to two sides first Spring arm 621 and the second spring arm 622, the second spring arm 622, which bends extension outward and is equipped with, extends spring arm 623, the extension of two torsional springs The end of spring arm 623 is linked together by linkage section 61, and the middle part of torsional spring ontology 62, which is formed, is pivotally connected the torsional spring that axis 9 passes through Mounting hole 601.

Further, the inner sidewall protrusion of the phase insulation box 5 is equipped with demarcation plate 51 inside of phase insulation box 5 is empty Between be divided into first accommodating cavity 511 of the top for installing arc-chutes 3 and the second accommodating cavity for installing quiescent contacting knife 4 512；The other side of the phase insulation box 5 is equipped with the semicircle shape shaft mounting groove 503 for evading big shaft 1；It is described alternate Insulation booth 5 is equipped with the gas vent 505 for exhaust close to the side wall that arc-chutes 3 go out arc side.

Further, the arc-chutes 3 include two blocks of arc extinguishing screens 31 and the muti-piece being installed between two blocks of arc extinguishing screens 31 Arc extinguishing grid pieces 32, the lower section of muti-piece arc extinguishing grid pieces 32 are equipped with the run-on tab 33 for striking；The muti-piece arc extinguishing grid pieces 32 and draw Arc plate 33 is arranged in parallel, and the middle part of run-on tab 33 is equipped with striking slot 332, and the middle part protrusion of striking slot 332 is equipped with striking protrusive board 331；Muti-piece arc extinguishing grid pieces 32 and run-on tab 33 are arranged diagonally downward towards big shaft 1, and the contact of quiescent contacting knife 4 extends to striking protrusive board 331 top.

The pivotal connection of the utility model breaker of plastic casing, movable touch knife and big shaft is not provided in the shaft of big shaft Heart position, and it is provided at one end of the contact in big shaft far from quiescent contacting knife, the center of rotation of movable touch knife more posteriorly, rotates the arm of force It is longer, when short circuit current flows through contact knife, after the reprimand that contact knife can be reached when smaller electric current flows through opens effect, and reprimand is opened Open away from bigger, can quick pull-up electric arc, product current limiting capacity and disjunction effect are improved, to improve the disjunction energy of breaker Power, it is especially especially pronounced compared with implementation result effective in small cavity in space.It illustrates, the pivot of above-mentioned movable touch knife and big shaft Junction is located at one end of the contact in big shaft far from quiescent contacting knife, i.e. pivotal connection is not the spindle central for being set to big shaft Place, and be provided at and deviate spindle central and one end far from stationary contact cutter-contact point, movable touch knife described in the utility model and big shaft Pivotal connection is located at the top of big shaft, is located remotely from the side of the contact of quiescent contacting knife.The utility model breaker of plastic casing is big The pivot structure that construction opening forms semi open model is arranged in shaft, and compared with existing enclosed big pivot structure, movable touch knife is answered Position spring is pivotally connected the easier for installation quick of axis 9.It is pivotally connected slot and is set as tip-angled shape gap slot, movable touch knife, reset Spring is pivotally connected after axis 9 is first completed, and can be mounted in big shaft from the side of big shaft along being pivotally connected slot and inwardly push away On, it is quickly and expediently installed, stable structure is reliable.

Detailed description of the invention

Schematic diagram when Fig. 1 is prior art movable touch knife center installation contact system closure；

Fig. 2 is the schematic diagram after installation contact system reprimand in prior art movable touch knife center is opened；

Fig. 3 is schematic diagram when the utility model movable touch knife installs contact system closure rearward；

Fig. 4 is that the utility model movable touch knife installs the schematic diagram after contact system reprimand is opened rearward；

Fig. 5 is the structural schematic diagram of main element inside the utility model breaker of plastic casing；

Fig. 6 is the structural schematic diagram of the big shaft of the utility model and movable touch knife installation；

Fig. 7 is the structural schematic diagram of the utility model movable touch knife；

Fig. 8 is the structural schematic diagram of the utility model reset spring；

Fig. 9 is the structural schematic diagram of the utility model arc-chutes.

Specific embodiment

Below in conjunction with the embodiment that attached drawing 3 to 9 provides, the specific reality of the breaker of plastic casing of the utility model is further illustrated Apply mode.The breaker of plastic casing of the utility model is not limited to the following description.

As shown in figs. 3-9, the utility model breaker of plastic casing including shell, is pivotally mounted to the big shaft of enclosure interior 1, the contact system of enclosure interior and the arc-chutes 3 of the electric arc for absorbing contact system generation, the contact system are installed on It including the movable touch knife 2 being pivotally mounted in big shaft 1 and is installed on enclosure interior and quiescent contacting knife 4 that movable touch knife 2 is oppositely arranged, moves Contact knife 2 and the pivotal connection of big shaft 1 are located at one end of the contact in big shaft 1 far from quiescent contacting knife 4.This reality of the utility model With novel plastic shell circuit breaker, the pivotal connection of movable touch knife and big shaft is not provided in the spindle central position of big shaft, but One end of contact in big shaft far from quiescent contacting knife, more posteriorly, the rotation arm of force is longer for the center of rotation of movable touch knife, works as short circuit When electric current flows through contact knife, the reprimand that contact knife can be reached when smaller electric current flows through opens effect, and reprimand open after open away from bigger, can With quick pull-up electric arc, product current limiting capacity and disjunction effect are improved, so that the breaking capacity of breaker is improved, especially in space It is especially pronounced compared with implementation result effective in small cavity.

It is monopole, bipolar or more as shown in figure 5, the utility model provides a kind of embodiment of three pole breaker of plastic casing Pole breaker of plastic casing is also suitable.It is additionally provided with inside the utility model breaker of plastic casing for completely cutting off the alternate exhausted of each pole conducting system Edge box 5, phase insulation box 5 are successively arranged side by side inside housings, and a pole conducting system is equipped in each phase insulation box 5 Arc-chutes 3 and contact system.Specifically, arc-chutes 3 are installed on the top of phase insulation box 5, and one end of quiescent contacting knife 4 is from alternate The side of insulation booth 5 is installed on the bottom of phase insulation box 5 across the lower section for stretching to arc-chutes 3, and big shaft 1 is located at phase insulation The other side of box 5, the movable touch knife 2 in big shaft 1 is passed through from the other side of phase insulation box 5 stretches to the entering in nock c of arc-chutes 3 Top positioned at contact knife 4 is oppositely arranged with quiescent contacting knife 4；One end that contact is arranged in the quiescent contacting knife 4 is equipped with U-shaped section 41, U-shaped section 41 U-shaped opening towards the side of phase insulation box 5, the contact of quiescent contacting knife 4 is set to the flat segments 411 that U-shaped section 41 is located at upside Upper surface, the U-shaped design of quiescent contacting knife 4 provides reverse current and obtains the reverse current with movable touch knife, to obtain reversed repulsion.This Utility model setting phase insulation box 5 is used to completely cut off each pole conducting system of breaker, and each pole conducting system can effectively insulate, Electrical Safety performance is improved, and is provided for each pole contact system and arc-chutes and box structure is individually installed, stable structure is reliable.

It illustrates, the pivotal connection of above-mentioned movable touch knife 2 and big shaft 1 is located at the touching in big shaft 1 far from quiescent contacting knife 4 One end of point, i.e. pivotal connection are not set at the spindle central of big shaft, and are provided at and are deviateed spindle central and far from quiet One end of contact knife contact, movable touch knife 2 described in the utility model are located at the top of big shaft 1 with the pivotal connection of big shaft 1, It is located remotely from the side of the contact of quiescent contacting knife 4.

As shown in figs 6-8, the movable touch knife 2 passes through reset spring 6 and is pivotally connected axis 9 and is installed in big shaft 1；Dynamic touching One end of knife 2 be equipped with be pivotally connected axis 9 installation cooperation mounting hole 201, big 1 top of shaft be equipped with and be pivotally connected axis 9 Both ends installation cooperation is pivotally connected slot 101, is pivotally connected axis 9 both ends and pivot after reset spring 6 and mounting hole 201 The installation of link slot 101 is fixed.Movable touch knife 2, which passes through reset spring 6 and is pivotally connected axis 9, to be installed in big shaft 1, and axis is pivotally connected 9 both ends cooperate with the installation of slot 101 is pivotally connected, and movable touch knife 2 can rotate in certain amplitude along movable touch knife 2, and stable structure can It leans on.

As shown in fig. 6, the specific structure of big shaft 1.The big shaft 1 includes the round axis body 15 and circular shaft at middle part The columned mounting post 16 for being used to install movable touch knife 2 of distribution setting on body 15, the lateral wall of round axis body 15 is adjacent two Protrusion, which is equipped with, between a mounting post 16 is used for annular projection 151.The big shaft 1 is cylindrical type shaft, and the top of big shaft 1 is opened Equipped with for installing movable touch knife 2, reset spring 6 and the construction opening 11 for being pivotally connected axis 9, construction opening 11 is set to mounting post On 16, construction opening 11 includes that the bottom notch of the first mounting groove 111 and the first mounting groove 111 that accommodate reset spring 6 is equipped with Movable touch knife for installing the other end of movable touch knife 2 stretches out slot 112, is pivotally connected the two sides that slot 101 is set to the first mounting groove 111 Side wall.The pivot structure that construction opening 11 forms semi open model is arranged in the big shaft 1 of the utility model breaker of plastic casing, with existing envelope The big pivot structure of enclosed is compared, and movable touch knife, is pivotally connected the easier for installation quick of axis 9 at reset spring.

Specifically, the slot 101 that is pivotally connected is tip-angled shape gap slot, and the open at one end for being pivotally connected slot 101 extends to The sidewall edge of construction opening 11, the tip one end for being pivotally connected slot 101 extend to big contact of the shaft 1 far from quiescent contacting knife 4 Side.It being pivotally connected slot 101 and is set as tip-angled shape gap slot, movable touch knife, reset spring are pivotally connected after axis 9 is first completed, It can be quickly and expediently installed, structure is steady in big shaft 1 from the side of big shaft 1 along inside push away of slot 101 is pivotally connected It is fixed reliable.Obviously, it is pivotally connected slot 101 or is set as and is pivotally connected the mounting hole of the installation cooperation of axis 9, such mode It needs to be pivotally connected by the way of axis 9 is packed into after.

As shown in figure 8, the torsion spring structure of reset spring 6.The reset spring 6 is torsion spring, is led between two torsional springs The connection of linkage section 61 is crossed, two torsional springs are located at the two sides of movable touch knife 2, and each torsional spring includes the torsional spring ontology 62 at middle part and turns round The the first spring arm 621 and the second spring arm 622 that spring ontology 62 extends to two sides, the second spring arm 622, which bends extension outward and is equipped with, to be prolonged Spring arm 623 is stretched, the end of the extension spring arm 623 of two torsional springs is linked together by linkage section 61, the middle part of torsional spring ontology 62 Formation is pivotally connected the torsional spring mounting hole 601 that axis 9 passes through.The utility model breaker of plastic casing reset spring uses torsion spring knot Structure, two torsional springs are located at positioned at the two sides of movable touch knife, and the reset of movable touch knife is more reliable and more stable.Extend setting for spring arm 623 The reseting elasticity for increasing reset spring 6 is set, so that the reset of movable touch knife is more fast and reliable.

As shown in figure 5, the inner sidewall protrusion of the phase insulation box 5 is equipped with demarcation plate 51 for the inside of phase insulation box 5 Space is divided into top for installing the first accommodating cavity 511 of arc-chutes 3 and the second accommodating cavity for installing quiescent contacting knife 4 512；The other side of the phase insulation box 5 is equipped with the semicircle shape shaft mounting groove 503 for evading big shaft 1；It is described alternate Insulation booth 5 is equipped with the gas vent 505 for exhaust close to the side wall that arc-chutes 3 go out arc side.Use is respectively set in phase insulation box 5 In the first accommodating cavity 511 and the second accommodating cavity 512, arc-chutes 3 and quiescent contacting knife 4 of installation arc-chutes 3 and installation quiescent contacting knife 4 Mounting structure it is reliable and stable, on phase insulation box 5 be arranged gas vent 505 be used for be discharged arc-chutes 3 generation hot gas, take Obtain preferable arc quenching effect.

As shown in figure 9, the specific structure of arc-chutes 3.The arc-chutes 3 include two blocks of arc extinguishing screens 31 and are installed on two Muti-piece arc extinguishing grid pieces 32 between block arc extinguishing screen 31, the lower section of muti-piece arc extinguishing grid pieces 32 are equipped with the run-on tab 33 for striking； The muti-piece arc extinguishing grid pieces 32 and run-on tab 33 are arranged in parallel, and the middle part of run-on tab 33 is equipped with striking slot 332, striking slot 332 Middle part protrusion is equipped with striking protrusive board 331；Muti-piece arc extinguishing grid pieces 32 and run-on tab 33 are arranged diagonally downward towards big shaft 1, stationary contact The contact of knife 4 extends to the top of striking protrusive board 331.The utility model breaker of plastic casing contact system is provided close to run-on tab 33 The electric arc that contact system generates quickly is introduced arc-chutes 3 and carries out arc extinguishing by lower section.The two of arc extinguishing grid pieces 32 and run-on tab 33 Side protrusion is equipped with the installation protrusion fixed with the installation of arc extinguishing screen, and arc extinguishing screen is equipped with mounting hole corresponding with installation protrusion, When installation, arc extinguishing grid pieces and run-on tab are sequentially inserted on arc extinguishing screen, are quickly and expediently installed.

3-4 illustrates the action process of the utility model breaker of plastic casing with reference to the accompanying drawing:

In closing of power circuit breaker "on" position, when the center of rotation of movable touch knife 2 moves back, and the rotation arm of force lengthens, axis 9 is touching The rotation center of knife 2, touch spring guarantee that movable touch knife 2 is reliably connected with quiescent contacting knife 4；When passing through short circuit current, 4 He of quiescent contacting knife Reversed electrodynamic repulsion force between movable touch knife 2, when movable touch knife 2 is moved to position shown in Fig. 4, reaches so that 2 stress of movable touch knife reprimand is opened Apart from farthest, reprimand opening force square is bigger, the short circuit current denounceed out is smaller, is more advantageous to arc extinction for movable touch knife 2 and quiescent contacting knife 4.? During this, the mechanism of breaker not full action, so that dynamic and static contact knife 4 quickly separates and pulls out the function of electric arc It is achieved.

It, cannot the above content is specific preferred embodiment further detailed description of the utility model is combined Assert that the specific implementation of the utility model is only limited to these instructions.For the ordinary skill of the utility model technical field For personnel, without departing from the concept of the premise utility, a number of simple deductions or replacements can also be made, should all regard To belong to the protection scope of the utility model.

Claims (10)

1. a kind of breaker of plastic casing, including shell, the big shaft (1) that is pivotally mounted to enclosure interior, it is installed on enclosure interior The arc-chutes (3) of contact system and the electric arc for absorbing contact system generation, it is characterised in that: the contact system includes pivot Turn the movable touch knife (2) being installed on big shaft (1) and be installed on the quiescent contacting knife (4) that enclosure interior is oppositely arranged with movable touch knife (2), Movable touch knife (2) and the pivotal connection of big shaft (1) are located at one end of the contact in big shaft (1) far from quiescent contacting knife (4).

2. breaker of plastic casing according to claim 1, it is characterised in that: further include the phase for completely cutting off each pole conducting system Between insulation booth (5), the arc-chutes (3) and contact system of a pole conducting system, arc-chutes are installed in each phase insulation box (5) (3) it is installed on the top of phase insulation box (5), one end of quiescent contacting knife (4) is passed through from the side of phase insulation box (5) stretches to arc extinguishing The bottom of phase insulation box (5) is installed below room (3), big shaft (1) is located at the other side of phase insulation box (5), big to turn Movable touch knife (2) on axis (1) is located at touching across entering for arc-chutes (3) is stretched to from the other side of phase insulation box (5) in nock (c) The top of knife (4) is oppositely arranged with quiescent contacting knife (4)；One end of quiescent contacting knife (4) setting contact is equipped with U-shaped section (41), U-shaped section (41) towards the side of phase insulation box (5), the contact of quiescent contacting knife (4) is set to U-shaped section (41) and is located at the flat of upside U-shaped opening The upper surface of straight section (411).

3. breaker of plastic casing according to claim 1 or 2, it is characterised in that: the movable touch knife (2) and big shaft (1) Pivotal connection is located at the top of big shaft (1), is located remotely from the side of the contact of quiescent contacting knife (4).

4. breaker of plastic casing according to claim 1 or 2, it is characterised in that: the movable touch knife (2) passes through reset spring (6) it and is pivotally connected axis (9) and is installed on big shaft (1)；One end of movable touch knife (2) be equipped with be pivotally connected axis (9) installation match The mounting hole (201) of conjunction, big shaft (1) top be equipped with be pivotally connected axis (9) both ends install cooperation be pivotally connected slot (101), axis (9) are pivotally connected and both ends and is pivotally connected slot (101) installation afterwards across reset spring (6) and mounting hole (201) and consolidates It is fixed.

5. breaker of plastic casing according to claim 4, it is characterised in that: the big shaft (1) is cylindrical type shaft, big to turn The top of axis (1) is offered for installing movable touch knife (2), reset spring (6) and the construction opening (11) for being pivotally connected axis (9), Construction opening (11) includes the bottom notch for accommodating first mounting groove (111) and the first mounting groove (111) of reset spring (6) Movable touch knife equipped with the other end for installing movable touch knife (2) stretches out slot (112), is pivotally connected slot (101) set on the first installation The two sides side wall of slot (111).

6. breaker of plastic casing according to claim 5, it is characterised in that: the slot (101) that is pivotally connected lacks for tip-angled shape Mouth slot, the open at one end for being pivotally connected slot (101) extend to the sidewall edge of construction opening (11), are pivotally connected slot (101) Tip one end extends to the side of the contact of big shaft (1) far from quiescent contacting knife (4).

7. breaker of plastic casing according to claim 5, it is characterised in that: the big shaft (1) includes the circular shaft at middle part The columned mounting post (16) for being used to install movable touch knife (2) of distribution setting on body (15) and round axis body (15), installation is opened Mouth (11) is set on mounting post (16), and the lateral wall of round axis body (15), which protrudes to be equipped between two neighboring mounting post (16), to be used In annular projection (151).

8. breaker of plastic casing according to claim 4, it is characterised in that: the reset spring (6) is torsion spring, two torsions It is connected between spring by linkage section (61), two torsional springs are located at the two sides of movable touch knife (2), and each torsional spring includes the torsion at middle part The the first spring arm (621) and the second spring arm (622) that spring ontology (62) and torsional spring ontology (62) extend to two sides, the second spring arm (622) bending outward, which extends to be equipped with, extends spring arm (623), and the end of the extension spring arm (623) of two torsional springs passes through linkage section (61) it links together, the middle part of torsional spring ontology (62), which is formed, is pivotally connected the torsional spring mounting hole (601) that axis (9) passes through.

9. breaker of plastic casing according to claim 2, it is characterised in that: the inner sidewall of the phase insulation box (5) protrudes The inner space of phase insulation box (5) is divided into top equipped with demarcation plate (51) and accommodates sky for installing the first of arc-chutes (3) Chamber (511) and the second accommodating cavity (512) for installing quiescent contacting knife (4)；The other side of the phase insulation box (5), which is equipped with, to be used In the semicircle shape shaft mounting groove (503) for evading big shaft (1)；The phase insulation box (5) goes out arc side close to arc-chutes (3) Side wall be equipped with for exhaust gas vent (505).

10. breaker of plastic casing according to claim 2, it is characterised in that: the arc-chutes (3) include two blocks of arc extinguishing screens (31) and the muti-piece arc extinguishing grid pieces (32) that are installed between two pieces of arc extinguishing screens (31), the lower section of muti-piece arc extinguishing grid pieces (32) is equipped with Run-on tab (33) for striking；The muti-piece arc extinguishing grid pieces (32) and run-on tab (33) are arranged in parallel, in run-on tab (33) Portion is equipped with striking slot (332), and the middle part protrusion of striking slot (332) is equipped with striking protrusive board (331)；Muti-piece arc extinguishing grid pieces (32) and draw Arc plate (33) is arranged diagonally downward towards big shaft (1), and the contact of quiescent contacting knife (4) extends to the top of striking protrusive board (331).