A direct-acting electromagnet for vacuum circuit breaker

Abstract

The present invention discloses a vacuum circuit breaker direct-acting electromagnet, which relates to the technical field of electromagnets, and comprises a static iron core and a moving iron core, wherein the moving iron core is opposite to the static iron core and can slide along the axial direction of the static iron core, and one end of the moving iron core close to the static iron core forms a first platform and the middle part of the first platform protrudes toward the static iron core to form a truncated cone or a polyhedral prism, and one end of the static iron core forms a second platform opposite to the first platform and the middle part of the second platform is concave to form a concave part adapted to the truncated cone or polyhedral prism on the moving iron core. The vacuum circuit breaker direct-acting electromagnet provided by the present invention increases the electromagnetic suction force without increasing the number of coil turns and current by adding a truncated cone or a polyhedral prism to the moving iron core; when the suction force is constant, the structure of the truncated cone or the polyhedral prism is added, and the required current value and the number of coil turns are less, thereby saving the use of copper materials and lowering energy consumption.

Description

Technical Field

[0001] The invention relates to the technical field of electromagnets, and in particular to a direct-acting electromagnet for a vacuum circuit breaker. Background Art

[0002] The electromagnet core in the prior art is as follows Figure 1 As shown, it is composed of a static iron core 1', a moving iron core 2', a push rod 3', a guide sleeve 4', etc. The push rod 3' is fixed to the moving iron core 2' by a nut 5'. In the initial position (separated), there is an air gap between the moving and static iron cores (Core action stroke), under the action of the magnetic field generated by the coil outside the core, the moving core 2' moves toward the static core 1' and is finally attracted together with the static core 1'. The suction force is calculated as follows:

[0003]

[0004] F-electromagnetic force, I-current, μ0-air magnetic permeability, N-number of coil turns,

[0005] A-core cross-sectional area, σ-air gap

[0006] From the above formula, it can be seen that if the air gap σ (core action stroke) is constant, if you want to increase the suction force, you need to increase the current value, or the number of coil turns, or the core area, which increases the amount of material used and the core diameter. Summary of the invention

[0007] In order to solve the above problems, the present invention provides a vacuum circuit breaker direct-acting electromagnet, which increases the electromagnetic attraction without increasing the number of coil turns and current under the same space conditions.

[0008] In order to achieve the above object, the present invention adopts the following technical solutions:

[0009] A vacuum circuit breaker direct-acting electromagnet comprises a stationary iron core and a moving iron core, wherein the moving iron core is opposite to the stationary iron core and can slide axially along the stationary iron core, a first platform is formed at one end of the moving iron core close to the stationary iron core, and a truncated cone or a polyhedral prism is formed by protruding from the middle of the first platform toward the stationary iron core, and a second platform opposite to the first platform is formed at one end of the stationary iron core, and a concave portion matching the truncated cone or the polyhedral prism on the moving iron core is formed by concave in the middle of the second platform.

[0010] Furthermore, the truncated cone or polyhedral pyramid is configured so that, when the first platform contacts the second platform, there is a gap between the conical surface of the truncated cone or the side surface of the polyhedral pyramid and the inner side wall of the corresponding recess on the static iron core, and there is a gap between the top surface of the truncated cone or the polyhedral pyramid and the top surface of the corresponding recess on the static iron core.

[0011] Furthermore, the vacuum circuit breaker direct-acting electromagnet also includes a yoke assembly, which includes an intermediate yoke in the shape of a hollow ring column and an upper yoke and a lower yoke respectively arranged at the upper and lower ends of the intermediate yoke, a coil frame is provided in the coil cavity surrounded by the upper yoke, the lower yoke and the intermediate yoke, and an inner and outer layers of coils are wound on the coil frame, the static iron core is located in the inner hole of the inner coil, and the moving iron core is arranged to be spaced opposite to the static iron core under normal conditions.

[0012] As a preferred embodiment, the intermediate magnetic yoke is composed of a first intermediate magnetic yoke and a second intermediate magnetic yoke which are coaxially arranged in the upper and lower parts in the shape of a hollow ring column, the first intermediate magnetic yoke is connected to the upper magnetic yoke, the second intermediate magnetic yoke is connected to the lower magnetic yoke, the static iron core and the moving iron core are both located in the inner hole of the coil frame, the static iron core is connected to the upper magnetic yoke, the moving iron core is connected to the lower magnetic yoke, and the spacing between the first intermediate magnetic yoke and the second intermediate magnetic yoke is the same as the spacing between the moving iron core and the static iron core.

[0013] Furthermore, the vacuum circuit breaker direct-acting electromagnet also includes a push rod, which sequentially passes through the lower magnetic yoke, the moving iron core, the static iron core and the upper magnetic yoke, the lower end of the push rod is fixedly connected to the lower magnetic yoke, and the upper end of the push rod passes through the upper magnetic yoke.

[0014] As another preferred embodiment, the upper and lower ends of the intermediate magnetic yoke are respectively connected to the upper magnetic yoke and the lower magnetic yoke, the static iron core is located in the inner hole of the coil frame and connected to the upper magnetic yoke, and the moving iron core is configured to be inserted into the lower magnetic yoke, and the upper end of the moving iron core extends into the inner hole of the coil frame opposite to the static iron core.

[0015] Furthermore, the vacuum circuit breaker direct-acting electromagnet also includes a push rod, which passes through the moving iron core, the static iron core and the upper magnetic yoke, the lower end of the push rod is fixedly connected to the moving iron core, and the upper end of the push rod passes through the upper magnetic yoke.

[0016] Furthermore, the inner and outer coils are a pull-in coil distributed in the inner layer and a holding coil distributed in the outer layer.

[0017] Furthermore, a micro switch is provided on the outer side of the upper end of the upper magnetic yoke, and the pins of the inner and outer coils both pass through the upper magnetic yoke upward and are connected with the micro switch.

[0018] Furthermore, the distance between the conical surface of the truncated cone or the side surface of the polyhedral pyramid and the inner side wall of the recess of the static iron core is smaller than the distance between the first platform and the second platform.

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] 1. The moving iron core is provided with a first platform, a truncated cone or a polyhedral prism is protruding in the middle of the first platform, and the static iron core is provided with a second platform, the middle of the second platform is concave to form a concave portion, and the truncated cone or the polyhedral prism cooperates with the concave portion, so that the actual air gap between the moving and static iron cores is reduced without changing the stroke of the moving iron core, and the electromagnetic suction force is increased without increasing the number of coil turns and the current; under the condition of a certain suction force, the structure of the truncated cone or the polyhedral prism is increased, and the required current value and the number of coil turns are less, thereby saving the use of copper materials and lowering energy consumption.

[0021] 2. The first platform and the second platform increase the suction holding force. There is no air gap between the platforms when they are suctioned, and the holding force generated is large under the same magnetic field strength.

[0022] 3. The truncated cone or polyhedral pyramid is configured so that when the first platform contacts the second platform, there is a gap between the conical surface of the truncated cone or the side surface of the polyhedral pyramid and the inner side wall of the corresponding recess on the static iron core, and there is a gap between the top surface of the truncated cone or the polyhedral pyramid and the top surface of the corresponding recess on the static iron core. In this way, when the gate is opened, the residual magnetism of the electromagnet is less (less electromagnetic attraction), which is conducive to increasing the opening speed.

[0023] 4. The present invention adopts a cylindrical surrounding yoke assembly, which has a large area and generates a large electromagnetic attraction.

[0024] 5. A double coil structure of a pull-in coil and a holding coil is adopted. In the initial position, due to the large air gap between the moving and static iron cores, in order to obtain sufficient suction, the ampere-turns (IN) value generated by the pull-in coil needs to be larger; when the moving iron core moves in the later stage and the distance between the moving and static iron cores is very close, the micro switch controls the holding coil to be energized, thereby reducing the ampere-turns (IN) value, which can meet the suction requirements and reduce the power consumption of the electromagnetic coil.

[0025] 6. The pull-in coil and the holding coil are coaxially wound into an inner and outer double-layer structure. Since the pull-in coil wire diameter is relatively thick, it is preferred to wind the pull-in coil in the inner layer and the holding coil in the outer layer. Under the same number of turns, the amount of copper can be saved; on the other hand, the holding coil is in a working state for a long time, and winding it in the outer layer is conducive to heat dissipation, preventing the holding coil from burning due to excessive temperature rise.

[0026] 7. When the micro switch controls the holding coil to be energized, the moving iron core slows down when approaching the static iron core and then closes. This prevents the moving iron core from hitting the static iron core at high speed when closing, thereby reducing the wear caused by the collision between the moving and static iron cores and increasing the service life of the moving and static iron cores. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 A half-section view of an iron core of a conventional electromagnet is shown;

[0028] Figure 2 It is a front view of the direct-acting electromagnet of the vacuum circuit breaker according to the first embodiment of the present invention;

[0029] Figure 3 is along Figure 2 Half section view along line AA;

[0030] Figure 4 is a cross-sectional view of the direct-acting electromagnet of the vacuum circuit breaker in the first embodiment of the present invention in the attracted state;

[0031] Figure 5 yes Figure 4 Enlarged view of point C in the middle;

[0032] Figure 6 1 is an exploded schematic diagram of a direct-acting electromagnet of a vacuum circuit breaker according to a first embodiment of the present invention;

[0033] Figure 7 is a schematic diagram of the coordination of the moving iron core and the stationary iron core of the first embodiment of the present invention;

[0034] Figure 8 is along Figure 7 Half section view along the midline BB;

[0035] Fig. 9 is a relationship diagram between the force value on the moving iron core and the air gap of the electromagnet in the first embodiment of the present invention;

[0036] Fig.10 It is a front view of the moving and static iron cores of the direct-acting electromagnet of the vacuum circuit breaker in the second embodiment of the present invention in the open state;

[0037] Fig.11 is along Fig.10 Sectional view along the mid-DD line;

[0038] Fig.12 is a cross-sectional view of the moving and static iron cores of the direct-acting electromagnet of the vacuum circuit breaker in the second embodiment of the present invention in the attracted state;

[0039] Fig.13 It is a schematic diagram of an exploded view of a direct-acting electromagnet of a vacuum circuit breaker according to a second embodiment of the present invention. DETAILED DESCRIPTION

[0040] The present invention will now be further described with reference to the accompanying drawings and specific implementation methods.

[0041] To further illustrate the various embodiments, the present invention provides drawings. These drawings are part of the disclosure of the present invention, which are mainly used to illustrate the embodiments and can be used in conjunction with the relevant descriptions in the specification to explain the operating principles of the embodiments. With reference to these contents, a person of ordinary skill in the art should be able to understand other possible implementations and advantages of the present invention. The components in the figures are not drawn to scale, and similar component symbols are generally used to represent similar components.

[0042] Example 1, please refer to Figures 2 to 9 The present embodiment provides a vacuum circuit breaker direct-acting electromagnet, including a moving iron core 8 and a stationary iron core 7. The moving iron core 8 is opposite to the stationary iron core 7 and can slide axially along the stationary iron core 7. One end of the moving iron core 8 close to the stationary iron core 7 forms a first platform 81, and the middle of the first platform 81 protrudes toward the stationary iron core 7 to form a truncated cone 12 or a polyhedral prism. One end of the stationary iron core 7 forms a second platform 71 opposite to the first platform 81, and the middle of the second platform 71 is concave to form a recessed portion that matches the truncated cone 12 or the polyhedral prism on the moving iron core 8.

[0043] The vacuum circuit breaker direct-acting electromagnet provided in this embodiment reduces the actual air gap between the moving and static iron cores without changing the stroke of the electromagnet by adding a truncated cone 12 or a polyhedral prism to the moving iron core 8, and increases the electromagnetic suction force without increasing the number of coil turns and current; when the suction force is constant, the structure of the truncated cone 12 or the polyhedral prism is added, and the required current value and number of coil turns are less, thereby saving the use of copper materials and lowering energy consumption. The first platform 81 and the second platform 71 increase the suction holding force. There is no air gap on the table when it is attracted, and the holding force generated under the same magnetic field strength is large.

[0044] Specifically, Figure 7 and Figure 8 As shown, the middle of the upper end surface of the moving iron core 8 is convex to form a truncated cone 12 or a polyhedral prism, and the middle of the lower end surface of the static iron core 7 is concave to form a concave portion that matches the truncated cone 12 or the polyhedral prism at the upper end of the moving iron core 8. The truncated cone 12 or the polyhedral prism is configured so that when the first platform 81 contacts the second platform 71, there is a gap between the side surface of the concave cone or the polyhedral prism and the inner side wall of the corresponding concave portion on the static iron core, and there is a gap between the top surface of the truncated cone or the polyhedral prism and the top surface of the corresponding concave portion on the static iron core, so that when the gate is opened, the residual magnetism of the electromagnet is less (less electromagnetic attraction), which is conducive to increasing the opening speed.

[0045] Preferably, the gap between the conical surface of the truncated cone or the side surface of the polyhedral pyramid and the inner wall of the corresponding recess on the static iron core is not less than 0.1 mm, and the gap between the top surface of the truncated cone or the polyhedral pyramid and the top surface of the corresponding recess on the static iron core is not less than 0.1 mm.

[0046] The distance between the conical surface of the truncated cone or the side surface of the polyhedral prism and the inner side wall of the concave portion of the static iron core is less than the distance between the first platform and the second platform. The angle between the conical surface of the truncated cone 12 or the side surface of the polyhedral prism and the horizontal plane is θ, preferably, θ is 30° to 75°, and in particular, when θ=45°, the electromagnetic attraction between the dynamic and static iron cores is maximum.

[0047] In the existing vacuum circuit breaker direct-acting electromagnet, the opposite end faces of the moving and static iron cores are both planes. The cross-sectional area of ​​the moving iron core 8 and the static iron core 7 in this embodiment is both A. If the opposite end faces of the moving and static iron cores are both planes with an area of ​​A, the air gap (i.e., the stroke) between the moving and static iron cores is σ. By providing a truncated cone 12 or a polyhedral prism on the moving iron core and a concave portion on the static iron core 7, in the initial position, as shown in FIG. Figure 6 As shown, the air gap (i.e., stroke) between the moving and static iron cores is reduced to σ1 = σcosθ, and at the same time, the relative effective area of ​​the moving iron core 8 and the static iron core 7 increases from area A to area A1 including the cone area of ​​the truncated cone 12 or the side area of ​​the polyhedral prism.

[0048] Suction formula:

[0049]

[0050] F-electromagnetic force, I-current, μ0-air magnetic permeability, N-number of coil turns,

[0051] A1-the end area of ​​the moving iron core close to the static iron core, σ1-the air gap

[0052] It can be seen from the suction formula that by arranging the truncated cone 12 or the polyhedral prism on the moving iron core 8, the current increases the electromagnetic suction force without increasing the number of coil turns. When the suction force is constant, adding the structure of the truncated cone 12 or the polyhedral prism requires fewer coil turns to achieve the required current value, reducing the power consumption of the coil and saving the use of copper materials.

[0053] The vacuum circuit breaker direct-acting electromagnet provided in this embodiment also includes a yoke assembly, which includes an intermediate yoke 3 in the shape of a hollow ring column and an upper yoke 2 and a lower yoke 4 respectively arranged at the upper and lower ends of the intermediate yoke 3. The coil cavity surrounded by the upper yoke 2, the lower yoke 4 and the intermediate yoke 3 is provided with inner and outer layers of coils, the static iron core 7 is located in the inner hole of the inner coil, and the moving iron core 8 is arranged to be spaced and opposite to the static iron core 7 in a normal state. The cylindrical surrounding yoke assembly formed by the upper yoke 2, the lower yoke 4 and the intermediate yoke 3 has a large area, so that the electromagnetic attraction generated by the electromagnet is large.

[0054] In a specific structure, such as Figure 3As shown, the inner and outer coils are the pull-in coil 10 and the holding coil 9, respectively, and the pull-in coil 10 and the holding coil 9 are coaxial. Since the pull-in coil 10 has a thicker wire diameter, preferably, the pull-in coil 10 is wound on the inner layer, and the holding coil 9 is wound on the outer layer, which can save the copper content of the coil under the same number of turns. On the other hand, the holding coil 9 is in a working state for a long time, and winding it on the outer layer is conducive to heat dissipation, preventing the holding coil 9 from burning due to excessive temperature rise.

[0055] More specifically, a coil frame 11 is provided in the coil cavity, and the pull-in coil 10 and the holding coil 9 are wound on the coil frame 11. The coil frame 11 has an inner hole, and the static iron core 7 is located in the inner hole of the coil frame 11. The moving iron core 8 is configured to penetrate the lower magnetic yoke 4, and the upper end of the moving iron core 8 extends into the inner hole of the coil frame 11 and is opposite to the static iron core 7. This structure enables the moving iron core 8 to reduce magnetic leakage.

[0056] The direct-acting electromagnet of the vacuum circuit breaker also includes a push rod 5, which passes through the moving iron core 8, the static iron core 7 and the upper magnetic yoke 2. The lower end of the push rod 5 is fixedly connected to the moving iron core 8 through a nut 6, and the upper end of the push rod 5 passes through the upper magnetic yoke 2.

[0057] In this embodiment, a micro switch 1 is provided on the outer side of the upper end of the upper magnetic yoke 2, and a through hole is provided on the upper magnetic yoke 2. The pins of the inner and outer coils are both passed upward through the through hole of the upper magnetic yoke 2 and then connected with the micro switch 1.

[0058] The relationship between the force on the moving iron core and the air gap is as follows: Fig. 9 As shown. A double coil structure of a pull-in coil 10 and a holding coil 9 is adopted. In the initial position, the micro switch 1 controls the pull-in coil 10 to be energized. Since the air gap between the moving and static iron cores is large, in order to obtain sufficient suction force, the ampere-turn (IN) value generated by the pull-in coil 10 needs to be large; when the moving iron core 8 moves in the later stage, when the moving and static iron cores are very close, the micro switch 1 controls the holding coil 9 to be energized and the pull-in coil is de-energized, thereby reducing the ampere-turn (IN), which can meet the suction force requirements and reduce the power consumption of the electromagnetic coil.

[0059] The micro switch 1 is used to set the coil switching point. The relationship between the force value on the moving iron core and the air gap of the electromagnet is as follows: Figure 7 As shown, the moving iron core 8 is slowed down when approaching the static iron core and then attracted, so as to avoid the moving iron core 8 hitting the static iron core 7 at high speed when attracted, thereby reducing the wear caused by the collision between the moving and static iron cores and increasing the service life of the iron core.

[0060] Example 2, Reference Figures 10 to 13The difference between the vacuum circuit breaker direct-acting electromagnet provided in this embodiment and the vacuum circuit breaker direct-acting electromagnet provided in the first embodiment is that: the intermediate magnetic yoke 3 is composed of a first intermediate magnetic yoke 31 and a second intermediate magnetic yoke 32 which are coaxially arranged in a hollow ring column shape, the first intermediate magnetic yoke 31 is fixedly connected to the upper magnetic yoke 2, the second intermediate magnetic yoke 32 is fixedly connected to the lower magnetic yoke 4, the static iron core 7 and the moving iron core 8 are both located in the inner hole of the coil frame, the static iron core 7 is fixedly connected to the upper magnetic yoke 2, the moving iron core 8 is fixedly connected to the lower magnetic yoke 4, the spacing between the first intermediate magnetic yoke 31 and the second intermediate magnetic yoke 32 is the same as the spacing between the moving iron core 8 and the static iron core 7, the push rod 5 passes through the lower magnetic yoke 4, the moving iron core 8, the static iron core 7 and the upper magnetic yoke 2 in sequence, the lower end of the push rod 5 is fixedly connected to the lower magnetic yoke 4, and the upper end of the push rod 5 passes through the upper magnetic yoke 2.

[0061] The second intermediate yoke is fixedly connected to the moving iron core, which is equivalent to becoming a part of the moving iron core. In this way, after the electromagnet is attracted, the contact area between the moving and static iron cores is equivalent to increasing the cross-sectional area of ​​the intermediate yoke, making the holding force of the electromagnet stronger, which is suitable for large-size circuit breakers.

[0062] The vacuum circuit breaker direct-acting electromagnet provided in the first and second embodiments of the present invention can be applied to a vacuum circuit breaker.

[0063] Although the present invention has been specifically shown and described in conjunction with the preferred embodiments, it should be understood by those skilled in the art that various changes may be made to the present invention in form and details without departing from the spirit and scope of the present invention as defined by the appended claims, all of which are within the scope of protection of the present invention.

Claims

1. A vacuum circuit breaker direct-acting electromagnet, characterized in that: It includes a static iron core and a dynamic iron core, the dynamic iron core is opposite to the static iron core and can slide axially along the static iron core, one end of the dynamic iron core close to the static iron core forms a first platform and protrudes from the middle of the first platform toward the static iron core to form a truncated cone or a polyhedral prism, one end of the static iron core forms a second platform opposite to the first platform and the middle of the second platform is concave to form a recess matched with the truncated cone or the polyhedral prism on the dynamic iron core; the truncated cone or the polyhedral prism is configured so that when the first platform contacts the second platform, there is a gap between the conical surface of the truncated cone or the side surface of the polyhedral prism and the inner side wall of the corresponding recess on the static iron core, and there is a gap between the top surface of the truncated cone or the polyhedral prism and the top surface of the corresponding recess on the static iron core.

2. The vacuum circuit breaker direct-acting electromagnet according to claim 1, characterized in that: The vacuum circuit breaker direct-acting electromagnet also includes a yoke assembly, which includes an intermediate yoke and an upper yoke and a lower yoke respectively arranged at the upper and lower ends of the intermediate yoke. A coil frame is provided in a coil cavity surrounded by the upper yoke, the lower yoke and the intermediate yoke, and an inner and outer layer of coils are wound on the coil frame. The static iron core is located in the inner hole of the inner layer of coil, and the moving iron core is arranged to be spaced opposite to the static iron core in a normal state.

3. The vacuum circuit breaker direct-acting electromagnet according to claim 2, characterized in that: The intermediate magnetic yoke is composed of a first intermediate magnetic yoke and a second intermediate magnetic yoke which are coaxially arranged in an upper and lower manner and are in the shape of a hollow ring column. The first intermediate magnetic yoke is connected to an upper magnetic yoke, and the second intermediate magnetic yoke is connected to a lower magnetic yoke. Both the static iron core and the moving iron core are located in the inner hole of the coil frame, the static iron core is connected to the upper magnetic yoke, and the moving iron core is connected to the lower magnetic yoke. The spacing between the first intermediate magnetic yoke and the second intermediate magnetic yoke is the same as the spacing between the moving iron core and the static iron core.

4. The vacuum circuit breaker direct-acting electromagnet according to claim 3, characterized in that: The vacuum circuit breaker direct-acting electromagnet also includes a push rod, which sequentially passes through the lower magnetic yoke, the moving iron core, the static iron core and the upper magnetic yoke. The lower end of the push rod is fixedly connected to the lower magnetic yoke, and the upper end of the push rod passes through the upper magnetic yoke.

5. The vacuum circuit breaker direct-acting electromagnet according to claim 2, characterized in that: The upper and lower ends of the middle magnetic yoke are respectively connected to the upper magnetic yoke and the lower magnetic yoke. The static iron core is located in the inner hole of the coil frame and connected to the upper magnetic yoke. The moving iron core is configured to penetrate the lower magnetic yoke. The upper end of the moving iron core extends into the inner hole of the coil frame and is opposite to the static iron core.

6. The vacuum circuit breaker direct-acting electromagnet according to claim 5, characterized in that: The vacuum circuit breaker direct-acting electromagnet also includes a push rod, which penetrates the moving iron core, the static iron core and the upper magnetic yoke. The lower end of the push rod is fixedly connected to the moving iron core, and the upper end of the push rod passes through the upper magnetic yoke.

7. The vacuum circuit breaker direct-acting electromagnet according to claim 3, characterized in that: The inner and outer coils are a pull-in coil distributed in the inner layer and a holding coil distributed in the outer layer.

8. The vacuum circuit breaker direct-acting electromagnet according to claim 3, characterized in that: A micro switch is arranged on the outer side of the upper end of the upper magnetic yoke, and the pins of the inner and outer coils both pass through the upper magnetic yoke upwards and are connected with the micro switch.

9. The vacuum circuit breaker direct-acting electromagnet according to any one of claims 1 to 8, characterized in that: The distance between the conical surface of the truncated cone or the side surface of the polyhedral pyramid and the inner side wall of the recess of the static iron core is smaller than the distance between the first platform and the second platform.

Images