GB2536765A

GB2536765A - Circuit breaker

Info

Publication number: GB2536765A
Application number: GB1600132.3A
Authority: GB
Inventors: Zhang Ye; Jiang Zhu Chun
Original assignee: Siemens AG
Current assignee: Siemens AG
Priority date: 2015-03-26
Filing date: 2016-01-05
Publication date: 2016-09-28
Anticipated expiration: 2036-01-05
Also published as: CN106158546B; CN106158546A; GB2536765B; GB201600132D0

Abstract

A circuit breaker comprises a moving contact 10, a static contact 20, an arc extinction chamber 30 and an electrically conducting plate or arc-striking runway 40 divided into first and second sections by a protruding part 40a directed towards an end of the fixed contact 20. The first section 41 has a free end close to an end of the moving contact and the second section 42 has a free end that extends into the arc extinction chamber. The protruding part is positioned closer to the static contact than any other part of the arc-striking runway. The distance between the static contact and runway may be no greater than the maximum separation of the contacts in a disconnected state. The breaker may comprise a current path 50, which may have an opening located on a side remote from the arc extinction chamber, a gas blowout plate 60, and a removable magnetism-enhancing plate 70, which may be disposed below the runway to form an arc gathering region A between the fixed contact and runway. The runway may further comprise a third section 43 that is connected to the free end of the second section 42 and extends into the arc extinction chamber in parallel.

Description

Circuit breaker

Technical field

The present invention relates to a circuit breaker, in particular to a residual current action circuit breaker or a miniature circuit breaker.

Background art

As is well known, a circuit breaker is a switch apparatus capable of switching on, carrying and switching off current under normal or abnormal circuit conditions. It is widely used in various kinds of production and various aspects of people's lives, due to the fact that it has a variety of protective functions such as overload, short circuit and undervoltage protection.

Typically, for example in the case of a residual current action circuit breaker having an overcurrent protection function (RCBO) or a miniature circuit breaker (MCB) product, when a short circuit current is broken, once the contacts have opened to form an arc, the question of whether the arc can jump quickly to the arc-striking runway, and enter the arc extinction chamber along the arc-striking runway, is of crucial importance to whether the product can safely and reliably extinguish the arc. If the arc cannot jump quickly to the arc-striking runway, and continues to burn in the region of the contacts, the moving and static contact will suffer serious effects, and even be destroyed by burning, so that the product functionality is lost completely. Meanwhile, the distance between the position of the base of the moving contact and the arc-striking runway once the moving contact has opened influences the speed at which the arc jumps. A smaller distance can ensure faster jumping, but may cause the arc to reignite -2 -behind the region of the contacts, so the phenomenon of arc return occurs, affecting the product's breaking performance.

To solve the above problem, there is an urgent need for those skilled in the art to develop a novel circuit breaker, so as to be able to ensure that it has better breaking performance.

Content of the invention An object of the present invention is to provide a circuit breaker which enables an arc to leave the region of contacts quickly after forming, and jump to an arc-striking runway, to reduce erosion by burning of the contacts by the arc.

Another object of the present invention is to provide a circuit breaker which enables an arc to be pushed quickly towards an arc extinction chamber, avoiding backwards movement of the arc or restrike in the region of the contacts.

The present invention provides a circuit breaker, comprising a pair of a moving contact and a static contact which cooperate with each other; an arc extinction chamber; and an arc-striking runway, having a protruding part directed towards an end of the static contact, the protruding part dividing the arc-striking runway into a first section and a second section, wherein a free end of the first section is close to an end of the moving contact, a free end of the second section extends into the arc extinction chamber, and the distance from the protruding part to the end of the static contact is less than the distance from any other point on the arc-striking runway to the end of the static contact. Since the arc-striking runway employs the design concept of being close to a contact tip of the moving contact, this helps the arc to leave the region of the contacts quickly after being formed, and jump onto the arc-striking runway, reducing erosion by burning of the contacts by the arc; moreover, a more ideal arc gathering region can also be formed between the static contact and a protruding point.

In another schematic embodiment of the circuit breaker, the distance from the protruding part to the end of the static contact is no greater than the distance between the static contact and the moving contact in a disconnected state. Since the distance between the arc and the static contact gradually decreases, and the resistance of air after ionization gradually decreases, the arc can reach the arc gathering region A between the static contact and the protruding point very easily when a short circuit current is broken.

In another schematic embodiment of the circuit breaker, also included is a current path having an opening, the opening being located on a side remote from the arc extinction chamber. Since the current path forms a non-closed annular structure, an auxiliary magnetic field formed by the current path can better drive the movement of the arc towards the arc extinction chamber, thereby making the breaking performance of the circuit breaker more stable.

In another schematic embodiment of the circuit breaker, the current path is formed by a current strip, the width of the current strip being smaller than the radius of a circumscribed circle of the current path, helping the current path to form a better auxiliary magnetic field, to better drive movement of the arc towards the arc extinction chamber.

In another schematic embodiment of the circuit breaker, the current path also comprises: a first soldering face and a second soldering face connected to two ends of the current strip, respectively, wherein the first soldering face is for connecting to the first section of the arc-striking runway, and the second soldering face is for flexibly connecting to an external conductor. -4 -

In another schematic embodiment of the circuit breaker, an angle of inclination of the first soldering face is the same as an angle of inclination of the free end of the first section.

In another schematic embodiment of the circuit breaker, also included is: a gas blow plate, disposed above the current path, but below the arc-striking runway. Since the arc-striking runway has the feature of a bend, a relatively closed space can be formed, and using a pressure difference of a gas flow field, fast-flowing gas can be formed at the position of the bend, helping to reduce lingering and backwards movement of the arc in that region.

In another schematic embodiment of the circuit breaker, also included is: a removable magnetism-enhancing plate, disposed below the arc-striking runway, and used for producing an auxiliary magnetic field; during circuit breaker disconnection, a horse-hoof-shaped arc gathering region is formed between the static contact and the arc-striking runway. The use of the non-closed current path and the magnetism-enhancing plate enable the magnetic field force produced during passage of current thereof to be utilized and enhanced as required, to drive the arc to leave the position of the bend and enter the arc extinction chamber, further avoiding lingering and backwards movement of the arc in that region.

In another schematic embodiment of the circuit breaker, the magnetism-enhancing plate is accommodated inside the current path at a predetermined separation, and remains electrically isolated from the current path.

In another schematic embodiment of the circuit breaker, an outer contour of the magnetism-enhancing plate is adapted to an inner contour of the current path. -5 -

In another schematic embodiment of the circuit breaker, the gas blow plate is provided with multiple locating ribs for fixing the magnetism-enhancing plate.

In another schematic embodiment of the circuit breaker, the gas blow plate is also provided with at least one mounting post respectively inserted in a corresponding mounting hole in the magnetism-enhancing plate.

In another schematic embodiment of the circuit breaker, once conducting, the arc of the arc gathering region forms a current loop, and the arc passes in sequence through the static contact, the arc gathering region, the first section of the arc-striking runway and the current path.

In another schematic embodiment of the circuit breaker, a third section which extends into the arc extinction chamber in parallel is also connected to the free end of the second section, to promote rapid extinction of the arc.

Description of the accompanying drawings

The accompanying drawings below merely illustrate and explain the present invention schematically, without defining the scope thereof. Drawings: Fig. 1 is a partial structural schematic diagram of the circuit breaker of the present invention; Fig. 2 is a partial structural schematic exploded view of the circuit breaker in Fig. 1; Fig. 3 is a schematic diagram of the current loop in the circuit breaker in Fig. 1.

Key to labels moving contact static contact arc extinction chamber arc-striking runway 40a protruding part 41 first section 42 second section 43 third section current path 51 current strip 52 first soldering face 53 second soldering face gas blow plate 61 locating rib 62 mounting post magnetism-enhancing plate 71 mounting hole A arc gathering region Particular ethbodiments To furnish a clearer understanding of the technical features, objects and effects of the present invention, particular embodiments of the present invention are now illustrated with reference to the accompanying drawings, in which identical labels indicate identical parts. In the drawings showing various embodiments, identical digits in the final two places indicate components with the same structure or components with similar structures but the same function.

To make the drawings appear uncluttered, only those parts relevant to the present invention are shown schematically in the drawings; they do not represent the actual structure thereof as a product. Furthermore, to make the drawings appear uncluttered for ease of understanding, in the case of components having the same structure or function in certain drawings, only one of these is drawn schematically, or only one is marked. -7 -

Referring to Fig. 1, this shows a partial structural schematic diagram of a schematic embodiment of the circuit breaker of the present invention. The circuit breaker comprises: a pair of a moving contact 10 and a static contact 20 which cooperate with each other, an arc extinction chamber 30, and an arc-striking runway 40. It is worth pointing out that, compared with a linear arc-striking runway generally used in the prior art, the arc-striking runway 40 in the circuit breaker of the present invention has the characteristic of a bend.

Specifically, in order to ensure that when a short circuit current is broken, the arc leaves the region of the contacts quickly after forming and jumps to a bend in the arc-striking runway, to reduce erosion by burning of the contacts by the arc, the arc-striking runway 40 is preferably arranged to bend towards a position close to the static contact 20. Combining Fig. 1 with Fig. 2, which shows a particular embodiment of the present invention, the arc-striking runway 40 has a protruding part 40a directed towards an end of the static contact 20. The protruding part 40a divides the arc-striking runway 40 into a first section 41 and a second section 42. More particularly, the first section 41 also has two ends, one of these ends of the first section 41 being connected to the protruding part 40a, the other end of the first section 41 being a free end; to facilitate fast jumping of the arc from the moving contact 10 to the arc-striking runway 40, the free end of the first section 41 is arranged to be close to an end of the moving contact 10. Moreover, the second section 42 also has two ends, one of these ends of the second section 42 being connected to the protruding part 40a, the other end of the second section 42 being a free end for extending into the arc extinction chamber 30. As Fig. 1 shows, more preferably, to facilitate entry of the arc into the arc extinction chamber 30 and fast extinction thereof, a further bend may be also provided in the second section 42; specifically, a third section 43 may also be connected to the free end of the second section 42, the third -8 --section 43 being able to extend into the arc extinction chamber 30 in parallel.

In order to form a more ideal arc gathering region, in particular, the distance from the protruding part 40a to the end of the static contact 20 is less than the distance from any other point on the arc-striking runway 40 to the end of the static contact 20. It should be understood that the structure and form of the protruding part 40a in the present invention are not restricted, for example the protruding part 40a between the first section 41 and second section 42 of the present invention may be a protruding arc forming a smooth transition, the protruding arc comprising a protruding tip at the shortest distance from the end of the static contact.

It is worth pointing out that, in order to enable the arc to reach the arc gathering region formed between the static contact 20 and the protruding point 40a very easily, according to a preferred embodiment of the present invention, the distance of the protruding part 40a to the end of the static contact 20 is no greater than the distance between the static contact 20 and the moving contact 10 in a disconnected state. Since the distance between the arc and the static contact 20 gradually decreases, and the resistance of air after ionization also gradually decreases, the arc will easily enter the arc gathering region A when a short circuit current is broken.

Furthermore, to enable the arc to jump to the arc-striking runway more quickly, and finally be channeled into the arc extinction chamber, to prevent restrike of the arc behind the region of the contacts and the phenomenon of arc return, referring to Figs. 2-3 the circuit breaker of the present invention also comprises: a current path 50 having an opening, the opening being located on a side remote from the arc extinction chamber 30. Since the current path 50 forms a non-closed annular structure, an auxiliary magnetic field formed by the current path 50 can better drive the movement of the arc -9 -towards the arc extinction chamber 30, thereby making the breaking performance of the circuit breaker more stable. According to a schematic embodiment of the present invention, the current path 50 is formed by a current strip 51; in order to enable the current path to better form an auxiliary magnetic field, the width of the current strip 51 is far smaller than the radius of the circumscribed circle of the current path 50.

To realize a connection between the current path and the arc-striking runway and an external conductor, the current path 50 also comprises: a first soldering face 52 and a second soldering face 53 connected to two ends of the current strip 51, respectively. Correspondingly, the first soldering face 52 on the current strip 51 is connected to the first section 41 of the arc-striking runway 40. According to an optional embodiment of the present invention, a soldering slot is also provided on the free end of the first section 41, with the first soldering face 52 on the current strip 51 being soldered to the soldering slot at the free end of the first section 41. The second soldering face 53 on the current strip 51 is connected flexibly to the external conductor. In order to better realize the connection between the current path 50 and the arc-striking runway 40, to form a smoothly connected current loop, according to a preferred embodiment of the present invention, an angle of inclination of the first soldering face 52 is kept the same as an angle of inclination of the free end of the first section 91.

In view of the fact that the provision of a gas flow field can further assist in channeling the arc quickly into the arc extinction chamber, the circuit breaker of the present invention is also provided with a gas blow plate 60. The gas blow plate 60 is provided above the current path 50, but below the arc-striking runway 40. According to an optional embodiment of the present invention, the gas blow plate 60 is made of nylon material, and can produce gas under the action of the high temperature of the arc, helping to form high gas pressure -10 -in a relatively closed space (such as a space formed by the arc-striking runway, moving contact, static contact, and certain housing components disposed nearby between the moving and static contacts); by making full use of the gas flow field in the region of the contacts, this helps to drive movement of the arc towards the arc extinction chamber. Meanwhile, since the arc-striking runway has a locally bent shape, a fast-flowing gas can be formed at the positions of the bends in the arc-striking runway, making use of the relatively closed space and a pressure difference of the gas flow field, helping to reduce lingering and backwards movement of the arc in this region.

Meanwhile, the circuit breaker of the present invention also comprises: a removable magnetism-enhancing plate 70, disposed below the arc-striking runway 40, for producing an auxiliary magnetic field. Optionally, the magnetism-enhancing plate 70 is an iron material with a relatively low magnetic resistance. Referring to Fig. 3 it can be seen that the dimensions of an outer contour of the magnetism-enhancing plate 70 are smaller than the dimensions of an inner contour of the current path 50, so that the magnetism-enhancing plate 70 is accommodated inside the current path 50 at a predetermined separation, and remains electrically isolated from the current path 50. Preferably, the outer contour of the magnetism-enhancing plate 70 is adapted to the inner contour of the current path 50.

To realize a connection between the gas blow plate 60 and the magnetism-enhancing plate 70, multiple locating ribs 61 are also provided on the gas blow plate 60, the locating ribs 61 being used for fixing the magnetism-enhancing plate 70. To further realize a fastening action, at least one mounting post 62 is also provided on the gas blow plate 60, while at least one mounting hole 71 is also provided in the magnetism-enhancing plate 70; the mounting post 62 is respectively inserted in the corresponding mounting hole 71 in the magnetism-enhancing plate 70. It should be pointed out that the structural form and number of the locating ribs 61 and mounting post 62 are not unique; those skilled in the art may make rational changes according to actual conditions. However, the magnetism-enhancing plate 70 in the present invention may or may not be fitted depending on product performance and cost requirements, or take over the action of the current path in a product with low breaking requirements.

Preferably, a horse-hoof-shaped arc gathering region A will form between the static contact 20 and the arc-striking runway 40 in the circuit breaker of the present invention during disconnection. Once conducting, the arc of the arc gathering region A will form a current loop, the specific current flow direction being as shown by the broken line in Fig. 3, i.e. the arc passes in sequence through the static contact 20, the arc gathering region A, the first section 41 of the arc-striking runway 40 and the current path 50, and finally flows out. When a closed circuit is formed in the current path 50, it is equivalent to a non-closed single-turn coil, and an electromagnetic field is produced in a middle region thereof, the magnetic field being gathered by the magnetism-enhancing plate 70 and thereby further enhanced; the arc current is subjected to an electromagnetic force under the action of the magnetic field, helping the arc to move quickly in the direction of the arc extinction chamber 30. Meanwhile, the arc-striking runway 40, moving contact 10, static contact 20, and certain housing components disposed nearby between the moving and static contacts form a relatively closed space; under the action of the energy of the arc, the amount of gas produced in that region by a casing and the gas blow plate 60 increases sharply, a gas pressure difference forms in the arc gathering region A, and is released to the outside through the direction of the arc extinction chamber 30, so the gas flow can help the arc to enter the arc extinction chamber quickly.

To enable those skilled in the art to understand the present invention more clearly, the principles of operation of the -12 -circuit breaker of the present invention will be described in detail in conjunction with Figs. 1 -3: When a short circuit current is broken, once the moving contact 10 and static contact 20 have opened under the action of the short circuit current, an arc forms in the region of the contacts, and with the assistance of a gas flow field and a magnetic field force, the arc moves quickly towards the region of a contact base of the moving contact 10, and after being stretched further, jumps onto the arc-striking runway 40; the arc enters the arc-striking runway 40 and moves towards the arc gathering region A, and once the arc has reached the arc gathering region A, the current loop formed by conduction through the arc can be seen in Fig. 3.

Analysis from the perspective of magnetic field force shows that: since the arc gathering region A is in a middle position of the current path, the magnetic field is relatively strong, helping the arc to enter the arc extinction chamber quickly under the action of the magnetic field force. Analysis from the perspective of gas flow field shows that: the arc gathering region A is at an opening of a relatively closed space, and when a gas flow produced in that region by the casing and the gas blow plate is released to the outside through the arc gathering region A, this can help the arc to enter the arc extinction chamber quickly. The above two effects can also effectively prevent backward movement of the arc to the region of the contacts; and even if restrike of the arc occurs behind due to the existence of a hot gas flow, the restrike position can be made to occur in the arc gathering region A as far as possible, reducing or avoiding secondary damage to the contacts by burning.

In summary, the arc-striking runway with a current path of the present invention has better arc-guiding performance than a conventional arc-striking runway. First of all, the arc jumps quickly in the present invention, and can leave the region of -13 -the moving contact quickly to enter the arc-striking runway, avoiding secondary restrike in the region of the contacts, and reducing erosion by burning of the contacts. Secondly, the present invention can make full use of the gas flow field in the region of the contacts, to drive movement of the arc towards the arc extinction chamber. Meanwhile, the auxiliary magnetic field formed by the current path can also better drive movement of the arc towards the arc extinction chamber, avoiding lingering and backwards movement of the arc in that region. The present invention can improve the breaking performance of a residual current action circuit breaker or a miniature circuit breaker product.

In this text, "schematic" means "serving as a real instance, an example or an illustration". No drawing or embodiment described as "schematic" herein should be interpreted as a more preferred or more advantageous technical solution.

It should be understood that although the description herein is based on various embodiments, it is by no means the case that each embodiment contains just one independent technical solution. Such a method of presentation is adopted herein purely for the sake of clarity. Those skilled in the art should consider the description in its entirety. The technical solutions in the various embodiments could also be suitably combined to form other embodiments capable of being understood by those skilled in the art.

The series of detailed explanations set out above are merely particular explanations of feasible embodiments of the present invention, which are not intended to limit the scope of protection thereof. All equivalent embodiments or changes made without departing from the artistic spirit of the present invention shall be included in the scope of protection thereof.

Claims

-14 -Claims 1. A circuit breaker, comprising: a pair of a moving contact (10) and a static contact (20) which cooperate with each other; an arc extinction chamber (30); and an arc-striking runway (40), having a protruding part (40a) directed towards an end of the static contact (20), the protruding part (40a) dividing the arc-striking runway into a first section (41) and a second section (42), wherein a free end of the first section (41) is close to an end of the moving contact (20), a free end of the second section (42) extends into the arc extinction chamber (30), and the distance from the protruding part (40a) to the end of the static contact (20) is less than the distance from any other point on the arc-striking runway (40) to the end of the static contact (20).
2. The circuit breaker as claimed in claim 1, wherein the distance from the protruding part (40a) to the end of the static contact (20) is no greater than the distance between the static contact (20) and the moving contact (10) in a disconnected state.
3. The circuit breaker as claimed in claim 1 or 2, also comprising: a current path (50) having an opening, the opening being located on a side remote from the arc extinction chamber (30).
4. The circuit breaker as claimed in claim 3, wherein the current path (50) is formed by a current strip (51), the width of the current strip (51) being smaller than the radius of a circumscribed circle of the current path (50).
5. The circuit breaker as claimed in claim 4, wherein the current path (50) also comprises: a first soldering face (52) and a second soldering face (53) connected to two ends of the current strip (51), respectively, wherein the first soldering -15 -face (52) is for connecting to the first section (41), and the second soldering face (53) is for flexibly connecting to an external conductor.
6. The circuit breaker as claimed in claim 5, wherein an angle of inclination of the first soldering face (52) is the same as an angle of inclination of the free end of the first section (41).
7. The circuit breaker as claimed in claim 3, also comprising: a gas blow plate (60), disposed above the current path (50), but below the arc-striking runway (40).
8. The circuit breaker as claimed in claim 7, also comprising: a removable magnetism-enhancing plate (70), disposed below the arc-striking runway (40), to form a horse-hoof-shaped arc gathering region (A) between the static contact (20) and the arc-striking runway (40) during circuit breaker disconnection.
9. The circuit breaker as claimed in claim 8, wherein the magnetism-enhancing plate (70) is accommodated inside the current path (50) at a predetermined separation, and remains electrically isolated from the current path (50).
10. The circuit breaker as claimed in claim 9, wherein an outer contour of the magnetism-enhancing plate (70) is adapted to an inner contour of the current path (50).
11. The circuit breaker as claimed in claim 8, wherein the gas blow plate (60) is provided with multiple locating ribs (61) for fixing the magnetism-enhancing plate (70).
12. The circuit breaker as claimed in claim 8, wherein the gas blow plate (60) is also provided with at least one mounting post (62) respectively inserted in a corresponding mounting hole (71) in the magnetism-enhancing plate (70).

-16 -
13. The circuit breaker as claimed in claim 12, wherein once conducting, the arc of the arc gathering region (A) forms a current loop, and the arc passes in sequence through the static contact (20), the arc gathering region (A), the first section (41) of the arc-striking runway (40) and the current path (50).
14. The circuit breaker as claimed in claim 1, wherein a third section (43) which extends into the arc extinction chamber (30) in parallel is also connected to the free end of the second section (42).