A self-reducing bellows assembly for circuit breaking and a vacuum interrupter.

Abstract

This invention relates to the field of power switchgear technology, and discloses a self-decelerating bellows assembly for circuit breaking and a vacuum interrupter. The bellows assembly includes a first bellows, a second bellows, and a connector. The connector is sleeved outside the moving contact rod of the vacuum interrupter. The first and second bellows are sleeved between the connector and the moving contact rod. A gas chamber is formed within the space enclosed by the connector, the second bellows, and a second movable member at the first end of the second bellows. In this invention, when the vacuum interrupter begins to open, the moving contact drives the first movable member to move away from the stationary contact. When the first movable member reaches a certain distance, it contacts and pushes the second movable member, compressing the second bellows. During this process, the gas in the gas chamber is compressed, the gas pressure increases, and a circuit breaking resistance is formed, thereby reducing the movement speed of the moving contact, mitigating the impact of contact opening distance changes on the longitudinal magnetic field strength, and reducing the failure rate of the vacuum interrupter.

Description

Technical Field

[0001] This invention relates to the field of power switchgear technology, and in particular to a self-reducing bellows assembly for tripping and a vacuum interrupter. Background Technology

[0002] In various current interruption scenarios involving power switchgear, ranging from low to high voltage, especially for long-arc interruption conditions simulated by the T100a test, the contacts inside the vacuum interrupter of the power switchgear need to have a certain longitudinal magnetic field strength B. AMF This is to ensure that the arc remains in a diffused state and to avoid the formation of harmful anode spots due to current accumulation. In the T100a test, due to the lack of a current zero point, as the contact gap increases beyond the short arc extinguishing distance d1, B... AMF The effect will gradually weaken as the opening distance increases; once B AMF Below the critical value, the original diffused arc will transform into a dotted arc or even an anode-shaped arc. At this time, the large amount of high-temperature plasma generated in the contact gap will cause the contact to fail to break at the zero current point. Summary of the Invention

[0003] This invention provides a self-decelerating bellows assembly for circuit breaking and a vacuum interrupter, which solves the technical problem that the longitudinal magnetic field strength of the vacuum interrupter contacts gradually weakens as the contact opening distance increases, which can easily lead to interruption failure.

[0004] The first aspect of the present invention provides a self-reducing bellows assembly for tripping circuits, which is applied to a vacuum interrupter. The self-reducing bellows assembly includes: a first bellows, a second bellows, and a connector.

[0005] The connector is used to be sleeved on the moving contact rod of the vacuum interrupter, and the first bellows and the second bellows are used to be sleeved between the connector and the moving contact rod.

[0006] The first end of the connector is used to be fixedly connected to the first end of the first bellows, and the second end of the connector is used to be fixedly connected to the outer shell of the vacuum interrupter and the second end of the second bellows.

[0007] The second end of the first bellows is provided with a first movable member, which is used to be fixedly connected to the moving contact rod.

[0008] The first end of the second bellows is provided with a second movable member;

[0009] An air chamber is formed within the space enclosed by the second movable member, the second bellows, and the connector.

[0010] Optionally, the second movable member is slidably and sealingly connected to the inner side of the connector.

[0011] Optionally, an exhaust channel is formed between the second movable member and the inner side of the connector.

[0012] Optionally, the difference between the outer diameter of the second movable member and the inner diameter of the connector is 0.05 to 0.5 times the inner diameter of the connector.

[0013] Optionally, when the moving contact is in the closed position, the distance between the first end of the bellows and the second movable member is less than the distance between the first end of the bellows and the first movable member when the moving contact moves from the closed position to the position of maximum arc extinguishing distance.

[0014] When the moving contact is in the closed position, the distance between the first end of the bellows and the second movable member is greater than the distance between the first end of the bellows and the first movable member when the moving contact moves from the closed position to the short arc extinguishing distance position.

[0015] Optionally, when the moving contact moves from the closed position to the short arc extinguishing distance position, the distance between the first moving part and the second moving part is 0.2 to 0.25 times the difference between the maximum arc extinguishing distance of the vacuum interrupter and the short arc extinguishing distance.

[0016] Optionally, when the vacuum interrupter is in the closed state, the distance between the first movable member and the second end of the second bellows is greater than the maximum value of the arc-extinguishing opening distance of the vacuum interrupter.

[0017] Optionally, a first fixing member is provided at the first end of the first corrugated pipe;

[0018] The first fixing member is sealed to the connecting member.

[0019] Optionally, a second fixing member is provided at the second end of the second corrugated pipe;

[0020] The second fastener is sealed to the connector.

[0021] A second aspect of the present invention provides a vacuum interrupter, comprising a housing, a stationary contact, a moving contact, and a self-reducing bellows assembly for opening circuits as described in any of the preceding claims;

[0022] The self-decelerating bellows assembly for tripping is sleeved on the moving contact rod. The first movable part of the self-decelerating bellows assembly for tripping is fixedly connected to the moving contact rod. The second end of the connecting part of the self-decelerating bellows assembly for tripping is fixedly connected to the outer shell.

[0023] As can be seen from the above technical solutions, the present invention has the following advantages:

[0024] This invention provides a self-reducing bellows assembly for circuit breaking and a vacuum interrupter. The self-reducing bellows assembly includes a first bellows, a second bellows, and a connector. The connector is sleeved outside the moving contact rod of the vacuum interrupter. The first and second bellows are sleeved between the connector and the moving contact rod. The first end of the connector is fixedly connected to the first end of the first bellows, and the second end of the connector is fixedly connected to the outer shell of the vacuum interrupter and the second end of the second bellows. The second end of the first bellows is provided with a first movable member, which is fixedly connected to the moving contact rod. The first end of the second bellows is provided with a second movable member. An air chamber is formed within the space enclosed by the second movable member, the second bellows, and the connector. In this invention, when the vacuum interrupter begins to open, the moving contact drives the first movable member to move away from the stationary contact, stretching the first bellows. When the moving contact moves to a certain distance, the first movable member contacts and pushes the second movable member, causing it to move away from the stationary contact and compressing the second bellows. During this process, the gas in the air chamber formed by the second movable member, the second bellows, and the connecting member is compressed, increasing the gas pressure and forming opening resistance, thereby reducing the movement speed of the moving contact, mitigating the influence of the contact opening distance change on the longitudinal magnetic field strength, and reducing the failure rate of the vacuum interrupter opening. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a schematic diagram of the structure of a self-reducing bellows assembly for tripping circuit breakers provided in an embodiment of the present invention;

[0027] Figure 2 This is a partially enlarged structural diagram of a self-decelerating bellows assembly for tripping circuits provided in an embodiment of the present invention.

[0028] Reference numerals: 1-stationary contact, 2-moving contact, 3-first fixed component, 4-first bellows, 5-first movable component, 6-second movable component, 7-second bellows, 8-second fixed component, 9-connector, 10-outer shell, 11-air chamber, 12-exhaust passage. Detailed Implementation

[0029] To enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0031] Unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0032] To address the technical problem of the longitudinal magnetic field strength of the vacuum interrupter contacts gradually weakening with increasing contact distance, which can easily lead to interruption failure, and to ensure the reliability of interrupting large currents during long arcing, it is necessary to guarantee the maximum longitudinal magnetic field B when the contacts move to each position within the arcing zone. max All must be greater than the critical magnetic field B that prevents anode spots from appearing. 临界 There are currently two main solutions:

[0033] 1. Using a traditional bellows structure, the longitudinal magnetic field strength B of the contacts is increased by extending the current path of the contacts. AMF Even if the longitudinal magnetic field strength B AMF The strength decreases as the contact gap increases, but it still satisfies the requirement of being greater than the critical magnetic field strength B. 临界 However, this method will make the current path of the contacts too long, increase the contact resistance, and hinder the effective flow of current. In addition, the contact structure needs to be adjusted to meet the current path requirements. The higher the voltage level of the arc-extinguishing chamber, the larger the corresponding contact volume, which is not conducive to the miniaturization of the vacuum arc-extinguishing chamber.

[0034] 2. During the interruption of a long arc, there exists a maximum arc-extinguishing distance d2. Due to the circuit breaker's tripping characteristics, the long and short arcs overlap in segment d1. Therefore, controlling the moving contact speed in the d1-d2 interval—that is, reducing the tripping speed in this segment and minimizing the travel distance—can mitigate the impact of the distance variation on the longitudinal magnetic field B. AMF The influence of this, thereby ensuring the magnetic field strength B of the contacts during the current interruption process. AMF Always higher than the required longitudinal magnetic field strength B 临界 To maintain the arc's diffusion pattern, an additional deceleration device is used to slow down the moving contact while using a conventional bellows structure. Deceleration methods include, but are not limited to, spring mechanism with oil buffer, electromagnetic mechanism with reversed magnetic poles, and reversed current, to achieve deceleration in the middle section of the moving contact opening process, thereby reducing the impact of opening distance changes on the longitudinal magnetic field B. AMF However, this method requires the addition of an extra deceleration device. The matching deceleration device is not only difficult to control the deceleration range accurately and has a limited deceleration effect, but also makes the entire switchgear structure more complex and costly.

[0035] Since both of the above-mentioned solutions have certain drawbacks, this invention proposes a self-decelerating bellows assembly for circuit breaking and a vacuum interrupter. The bellows assembly structure of the vacuum interrupter itself decelerates the moving contact, solving the technical problem that the longitudinal magnetic field strength of the vacuum interrupter contacts gradually weakens as the contact opening distance increases, easily leading to interruption failure. Furthermore, the bellows assembly structure is simple and has low production costs. The following provides a detailed description of an embodiment of the self-decelerating bellows assembly and vacuum interrupter of this invention.

[0036] Please see Figure 1 Embodiment 1 of the present invention provides a self-decelerating bellows assembly for opening a vacuum interrupter, comprising: a first bellows 4, a second bellows 7, and a connector 9;

[0037] The connector 9 is used to be sleeved on the moving contact 2 rod of the vacuum interrupter, and the first bellows 4 and the second bellows 7 are used to be sleeved between the connector 9 and the moving contact 2 rod.

[0038] The first end of the connector 9 is used to be fixedly connected to the first end of the first bellows 4, and the second end of the connector 9 is used to be fixedly connected to the outer shell 10 of the vacuum interrupter and the second end of the second bellows 7.

[0039] The second end of the first bellows 4 is provided with a first movable member 5, which is used to be fixedly connected to the rod of the moving contact 2.

[0040] The first end of the second bellows 7 is provided with a second movable part 6;

[0041] An air chamber 11 is formed within the space enclosed by the second movable component 6, the second bellows 7, and the connector 9.

[0042] It should be noted that the first movable part 5 and the second movable part 6 are respectively located at the ends of the first bellows 4 and the second bellows 7, and preferably use standardized ring-shaped fittings such as flanges; the rod of the moving contact 2 and the first movable part 5 can slide within the connecting part 9, which provides a stable support platform for the moving contact 2, ensuring that the moving contact 2 can move accurately and reliably during the opening and closing operation.

[0043] Specifically, the first end of the first bellows 4 may be provided with a first fixing member 3, which is sealed to the connector 9, preferably by airtight welding; the second end of the second bellows 7 may be provided with a second fixing member 8, which is sealed to the connector 9, preferably by airtight welding; the first fixing member 3 and the second fixing member 8 can effectively distribute the force borne by the bellows (such as the push-pull force when the contacts open and close) to the connector 9, reducing the stress concentration of the bellows body. The first fixing member 3 and the second fixing member 8 are preferably ring-shaped structural parts such as flanges that facilitate sealing connection; in the bellows assembly and vacuum interrupter provided by the present invention, the fixed connection between each component is a sealed connection, preferably by airtight welding. The joint formed by airtight welding has mechanical strength equivalent to or close to that of the base material, can withstand large tensile, shear, bending and torsional stresses, and the joint surface is continuous and seamless, with almost no micro gaps or channels, and can achieve an extremely high sealing level.

[0044] It is understandable that when the vacuum interrupter is in the closed state, the internal space enclosed by the first bellows 4, the first moving part 5, the outer shell 10, and the connecting part 9 is a vacuum environment, while the gas chamber 11 is in an uncompressed state, and its internal gas pressure is equal to the external gas pressure. When the vacuum interrupter begins to open, the moving contact 2 drives the first moving part 5 to move away from the stationary contact 1, stretching the first bellows 4. When the moving contact moves to a certain distance, the first moving part 5 contacts and pushes the second moving part 6, driving it to move away from the stationary contact 1, compressing the second bellows 7. During this process, the gas in the gas chamber 11 enclosed by the second moving part 6, the second bellows 7, and the connecting part 9 is compressed. According to the ideal gas equation PV=nRT, the gas pressure in the gas chamber 11 increases, which in turn forms a resistance to the moving contact through the first moving part 5 and the second moving part 6, reducing the movement speed of the moving contact, mitigating the influence of the contact opening distance change on the longitudinal magnetic field strength, and reducing the failure rate of the vacuum interrupter. Compared to arc-extinguishing chambers using conventional bellows and the same contact structure, arc-extinguishing chambers using the bellows assembly provided by this invention can increase the longitudinal magnetic field strength during contact breaking, significantly improving breaking capacity. Furthermore, the bellows assembly provided by this invention has only a few more parts than conventional bellows. Compared to existing solutions that add additional deceleration devices, using this bellows assembly simplifies the design of the vacuum arc-extinguishing chamber and the corresponding circuit breaker, avoiding excessive system complexity, greatly reducing the production cost of the vacuum arc-extinguishing chamber, and allowing for smaller size and more controllable overall characteristics. Compared to existing solutions that extend the current path by adjusting the contact structure, using this bellows assembly not only does not affect current flow but also does not require increasing the contact volume, which is beneficial for arc-extinguishing chamber miniaturization. Moreover, this bellows assembly can be applied to vacuum arc-extinguishers of different voltage levels, with a more significant effect at higher voltage levels, especially when applied to medium-voltage vacuum arc-extinguishers (above 72.5kV, below 126kV) and high-voltage vacuum arc-extinguishers (126kV and above).

[0045] Since the second bellows 7 still has a certain length after being fully compressed, when the vacuum interrupter is in the closed state, the distance between the first moving part 5 and the second end of the second bellows 7 must be greater than the maximum value of the arc-extinguishing opening distance of the vacuum interrupter.

[0046] In one specific embodiment, when the moving contact 2 is in the closed position, the distance between the first end of the first bellows 4 and the second movable member 6 is less than the distance between the first end of the first bellows 4 and the first movable member 5 when the moving contact 2 moves from the closed position to the position of maximum arc extinguishing distance. The outer diameter of the first movable member 5 is greater than the inner diameter of the second movable member 6, so that during the movement of the moving contact 2, the first movable member 5 can contact the second movable member 6 and push the second movable member 6.

[0047] Furthermore, when the moving contact 2 is in the closed position, the distance between the first end of the first bellows 4 and the second movable member 6 is greater than the distance between the first end of the first bellows 4 and the first movable member 5 when the moving contact 2 moves from the closed position to the short arc extinguishing distance position. This ensures that the first movable member 5 will only contact the second movable member 6 after the moving contact 2 moves to the short arc extinguishing distance position.

[0048] Furthermore, when designing the dimensions of each component of the bellows assembly, technicians can appropriately reduce the length of the second bellows 7 to make the pressure difference change in the air chamber 11 more obvious, thereby enhancing the deceleration effect of the bellows assembly on the moving contact.

[0049] In a preferred embodiment, the second movable member 6 is slidably sealed to the inner side of the connecting member 9, so that after the second movable member 6 is pushed by the first movable member 5, the air chamber 11 is compressed, the internal air pressure rises, and the opening resistance is generated; the sliding sealing connection can be achieved by means of packing seal, mechanical seal, labyrinth seal, etc.

[0050] Because the structure for implementing a sliding seal connection is complex and costly, in another preferred embodiment, please refer to... Figure 2 An exhaust channel 12 is formed between the outer side of the second movable member 6 and the inner side of the connecting member 9. This means that the outer side of the second movable member 6 and the inner side of the connecting member 9 are either not sealed or have no connection at all, leaving a gap for the exhaust channel 12. After the second movable member 6 is pushed by the first movable member 5, although the second movable member 6 and the connecting member 9 are not sealed and gas can escape, the small area of ​​the exhaust channel 12 prevents the gas from being discharged in time, leading to an increase in the gas pressure inside the gas chamber 11, thus creating resistance to the tripping action.

[0051] The smaller the difference between the outer diameter of the second movable part 6 and the inner diameter of the connecting part 9, the smaller the area of ​​the exhaust channel 12, and the more significant the deceleration effect. In accordance with the tolerance zones of the second movable part 6 and the connecting part 9, the difference between the outer diameter of the second movable part 6 and the inner diameter of the connecting part 9 is preferably 0.05 to 0.5 times the inner diameter of the connecting part 9. For example, the inner diameter of the connecting part 9 is φ100 (0.05, 0), and the outer diameter of the second movable part 6 is φ100 (-0.05, -0.45).

[0052] In a preferred embodiment, please refer to Figure 2 When the moving contact 2 moves from the closed position to the short arc extinguishing distance position, the distance ΔX between the first moving part 5 and the second moving part 6 is 0.2 to 0.25 times the difference between the maximum arc extinguishing distance d2 of the vacuum interrupter and the short arc extinguishing distance d1.

[0053] It should be noted that when the moving contact 2 moves from the closed position to the short arc extinguishing distance position, the first moving part 5 also moves from its initial position to... Figure 2The distance ΔX between the d1 position of the first movable member 5 and the initial position of the second movable member 6 can be adjusted by changing the length of the first bellows 4 or the second bellows 7. Since the deceleration of the moving contact 2 takes time, it needs to start decelerating before the moving contact 2 reaches the maximum value of the arc extinguishing distance. Usually, d2 is twice d1. For example, if d1 is 20mm and d2 is 40mm, then ΔX can be set to 4mm to 5mm, which means that the moving contact 2 starts to decelerate when it moves to the position of short arc extinguishing distance + ΔX, and the speed has already decreased when it moves to the position of the maximum value of the arc extinguishing distance.

[0054] When the structure of the second movable member 6 and the inner side of the connecting member 9 are in a sliding seal connection, there is a linear relationship between the opening resistance generated by the bellows assembly and ΔX. However, when the structure of the second movable member 6 and the inner side of the connecting member 9 are adapted but not connected, the relationship between the opening resistance generated by the bellows assembly and ΔX is not linear because the gas in the gas chamber 11 will be partially leaked through the exhaust channel 12. Technicians can adjust the distance between the first movable member 5 and the second movable member 6 when the moving contact 2 moves from the closed position to the short arc extinguishing distance position by measuring the speed change of the moving contact 2 in the d1 to d2 section. This can prevent the speed and deceleration of the moving contact 2 from being too slow or too fast. For example, if the speed value of the moving contact 2 in the d1 to d2 section is greater than the speed value required to avoid the appearance of anode spots, ΔX can be appropriately reduced.

[0055] Embodiment 2 of the present invention provides a vacuum interrupter, including a shell 10, a stationary contact 1, a moving contact 2, and a self-reducing bellows assembly for opening the circuit as described in any of the above embodiments;

[0056] The self-decelerating bellows assembly for tripping is sleeved on the moving contact 2 rod. The first movable part 5 of the self-decelerating bellows assembly for tripping is fixedly connected to the moving contact 2 rod. The second end of the connecting part 9 of the self-decelerating bellows assembly for tripping is fixedly connected to the outer shell 10.

[0057] Specifically, the housing 10 can be made of ceramic. Ceramic materials such as alumina ceramics and electrical porcelain have high insulation resistance and withstand voltage strength, and can provide excellent electrical insulation performance in high-voltage environments.

[0058] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working process and principle of the vacuum interrupter described above can be referred to the corresponding description in the aforementioned embodiment of the self-decelerating bellows assembly for circuit breaking, and will not be repeated here.

[0059] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A self-reducing bellows assembly for tripping circuits, used in a vacuum interrupter, characterized in that, include: First corrugated pipe, second corrugated pipe, and connectors; The connector is used to be sleeved on the moving contact rod of the vacuum interrupter, and the first bellows and the second bellows are used to be sleeved between the connector and the moving contact rod. The first end of the connector is used to be fixedly connected to the first end of the first bellows, and the second end of the connector is used to be fixedly connected to the outer shell of the vacuum interrupter and the second end of the second bellows. The second end of the first bellows is provided with a first movable member, which is used to be fixedly connected to the moving contact rod. The second bellows has a second movable component at its first end; An air chamber is formed within the space enclosed by the second movable member, the second bellows, and the connector, and an exhaust channel is formed between the inner sides of the second movable member and the connector.

2. The self-reducing bellows assembly for tripping according to claim 1, characterized in that, The difference between the outer diameter of the second movable component and the inner diameter of the connecting component is 0.05 to 0.5 times the inner diameter of the connecting component.

3. The self-reducing bellows assembly for tripping according to claim 1, characterized in that, When the moving contact is in the closed position, the distance between the first end of the first bellows and the second movable member is less than the distance between the first end of the first bellows and the first movable member when the moving contact moves from the closed position to the position of the maximum arc extinguishing distance. When the moving contact is in the closed position, the distance between the first end of the first bellows and the second movable member is greater than the distance between the first end of the first bellows and the first movable member when the moving contact moves from the closed position to the short arc extinguishing distance position.

4. The self-reducing bellows assembly for tripping according to claim 1, characterized in that, When the moving contact moves from the closed position to the short arc extinguishing distance position, the distance between the first moving part and the second moving part is 0.2 to 0.25 times the difference between the maximum arc extinguishing distance of the vacuum interrupter and the short arc extinguishing distance.

5. The self-reducing bellows assembly for tripping according to claim 1, characterized in that, When the vacuum interrupter is in the closed state, the distance between the first movable member and the second end of the second bellows is greater than the maximum value of the arc-extinguishing opening distance of the vacuum interrupter.

6. The self-reducing bellows assembly for tripping according to claim 1, characterized in that, The first end of the first corrugated pipe is provided with a first fixing member; The first fixing member is sealed to the connecting member.

7. The self-reducing bellows assembly for tripping according to claim 1, characterized in that, The second end of the second corrugated pipe is provided with a second fixing member; The second fastener is sealed to the connector.

8. A vacuum interrupter, characterized in that, Includes a housing, a stationary contact, a moving contact, and a self-reducing bellows assembly for tripping as described in any one of claims 1 to 7; The self-decelerating bellows assembly for tripping is sleeved on the moving contact rod. The first movable part of the self-decelerating bellows assembly for tripping is fixedly connected to the moving contact rod. The second end of the connecting part of the self-decelerating bellows assembly for tripping is fixedly connected to the outer shell.

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