Magnetic attraction type electromagnetic switch and armature piece for improving breaking speed

Abstract

To provide a magnetic attraction type electromagnetic switch and an armature piece for improving a breaking speed.SOLUTION: A coil assembly including an induction coil and an iron core, a support frame assembly including a fixed piece and an elastic member, a magnetic pole assembly including an armature piece and a contact conduction member fixedly disposed on one side of the armature piece, and a fixed contact assembly including a base and at least one fixed contact disposed on the base; At least one surface of the fixed plate is disposed on the coil assembly to form an extension end, the elastic member is disposed on the fixed plate, the upper end edge of the armature plate is pivotally connected to the extension end and is fixedly connected to one end of the elastic member, the armature plate is provided with at least one demagnetizing opening, and the demagnetizing opening is located on the other end side opposite to the pivotal connection end edge of the armature plate and the fixed plate.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to the field of electromagnetic switches, and more particularly to a magnetically attracted electromagnetic switch and armature that can effectively improve the interruption speed, thereby being suitable for application to electrical equipment that meets the limiting standards that require rapid disconnection, such as energy storage equipment, and is used to maintain the stability of running operation. [Background technology]

[0002] Conventionally, the operating principle of a typical electromagnetic switch is that its induction coil controls electrical continuity by utilizing the magnetic attraction force generated before and after power is supplied to activate the movable and fixed contacts on the switch, thereby activating or closing the contacts. Although power supply activates the electromagnetic switch, the momentary operation is perceived as only momentary, but in actual equipment operation, excessive "operation time" or "interruption time" can still adversely affect the equipment's operation. The so-called "operation time" is defined as the time it takes for the movable contacts on the switch to make electrical contact with the fixed contacts after power is supplied, while the "interruption time" refers to the time it takes for the movable and fixed contacts on the switch to return to their interrupted state and become electrically non-conductive after power is removed. Logically, equipment operation can only be initiated when the switch is in an electrically conductive state. Therefore, as is often the case, consideration is given to quickly driving the operation of equipment to meet the demands of urgent situations or work efficiency, and in practice, the topic of improvement, research and development, and exploratory discussion is usually on how to make the contacts of the switch make contact and quickly establish an electrical conduction state after the current is turned on, that is, how to reduce the "work time".

[0003] However, for specialized applications such as energy storage and charging equipment, reducing the "breaking time" is just as important as the "operation time." For example, high safety standards are required to reduce the "breaking time" of electromagnetic switches to less than 5 milliseconds, even down to 2 milliseconds. Theoretically, the process of moving the moving contact of an electromagnetic switch to the fixed contact typically requires overcoming two repulsive forces. These two repulsive forces refer to the "elastic member repulsive force" that maintains the moving contact in a normally open state using an elastic member, and the "contact repulsive force" that occurs when the moving contact first makes contact with the fixed contact. Therefore, intuitively, increasing the breaking speed between contacts requires increasing the two acting forces, the "elastic member repulsive force" and the "contact repulsive force." However, this is simply a breakthrough point, and after power is supplied to one side, the attractive force of magnetic conduction must be increased synchronously, and only after overcoming the two repulsive forces can the normal operation of the switch be maintained. After that, the power supply alone can be naturally increased again to increase the output power of the coil. Therefore, this method will result in additional and unnecessary power loss, and is not necessarily an appropriate means of implementation. Summary of the Invention [Problem to be solved by the invention]

[0004] In light of this, the team of the present invention has carefully considered the logic and suitable solutions for reducing the "breaking time" that are not found in existing technology, and has finally provided an electromagnetic switch structure that can significantly reduce the "breaking time" while still maintaining the level of the "operating time" of the original electromagnetic switch without relying on a method of increasing the power supply.

[0005] The main object of the present invention is to provide an electromagnetic switch that can maintain normal driving operation by breaking and closing its movable contact and fixed contact before and after power supply, while at the same time obtaining technical means for significantly reducing the "breaking time." [Means for solving the problem]

[0006] In order to achieve the above object, the present invention discloses a magnetic attraction type electromagnetic switch that improves the breaking speed. The magnetic attraction type electromagnetic switch comprises a coil assembly having an induction coil and an iron core located on the axial direction of the induction coil, a support assembly having a fixed piece and an elastic member, a magnetic pole assembly having an armature piece and a contact conducting member, and a fixed contact assembly having a base and at least one fixed contact provided on the base, wherein at least one surface of the fixed piece is installed on the coil assembly and one portion is extended to form an extended end, the elastic member is installed on the fixed piece and one end of the elastic member is fixed to the fixed piece, the contact conducting member is fixed to one side of the armature piece and operates synchronously, the contact conducting member also has at least one movable contact, the upper end edge of the armature piece is pivotally connected to the extended end of the fixed piece and fixed to the other end of the elastic member, and the armature piece is connected to the unpassivated part of the coil assembly. When the coil assembly is energized, a tensile force of the elastic member causes the armature piece to be positioned at an open position; when the coil assembly is energized, a magnetic force is generated, causing the armature piece to pivot toward the iron core and be positioned at a closed position; there is an air gap between the armature piece and the iron core, and the air gap in the open position gradually increases from the upper edge where the armature piece and the fixed piece are pivotally attached to each other toward the lower edge of the other end of the armature piece; the base supports and places the coil assembly; the fixed contacts are disposed corresponding to the movable contacts; when the armature piece is positioned at the closed position, the movable contacts come into contact with the fixed contacts to establish electrical continuity; and the armature piece has at least one demagnetization aperture disposed on the other end of the pivotally attached end of the armature piece and the fixed piece, the demagnetization aperture being located at the opposite end of the pivotally attached end of the armature piece.

[0007] More preferably, the demagnetization aperture has a hole shape that is symmetrical with respect to a virtual mirror-imaged reference line defined by the midpoint between the left and right ends of the armature piece. For example, the demagnetization aperture has a stripe-like hole shape extending from the virtual mirror-imaged reference line toward the left and right of the armature piece, or the demagnetization aperture has a hat-shaped hole shape formed after being mirror-imaged left and right about the virtual mirror-imaged reference line, and includes a hat edge groove and a hat top groove, the hat top groove being expressed as protruding toward the upper edge of the armature piece. More preferably, the hat top groove protrudes in an arc shape, giving the demagnetization aperture an Ω-shaped hole shape. Alternatively, and more preferably, the demagnetization openings are composed of a number of parallel strip-shaped holes, and the distance between the strip holes superimposed on the virtual mirror reference line and the lower edge of the armature piece is relatively larger than the distance between the other strip holes and the lower edge of the armature piece. [Effects of the Invention]

[0008] In summary, the magnetically attracted electromagnetic switch with improved interruption speed provided by the present invention, thanks to the special structural design of the armature, can maintain the strength of the original electromagnetic switch's opening and closing attractive force at the same power supply level, allowing it to operate normally. In other words, by installing the demagnetization opening and the corresponding opening at a specific position on the armature, the magnetic conduction path on the armature can be broken, thereby increasing the demagnetization speed and shortening the "interruption time," while not substantially affecting the magnetic switch's attractive force. It can be used for various electrical devices that meet strict standards requiring rapid disconnection, such as energy storage equipment, and can effectively maintain operational stability. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is an exploded view of an electromagnetic switch according to a preferred embodiment of the present invention; [Figure 2]FIG. 2 is a combination diagram of an electromagnetic switch according to a preferred embodiment of the present invention. [Figure 3] 10A and 10B are diagrams showing demagnetization openings of an armature piece according to an experimental example of the present invention. [Figure 4] 1 is a diagram showing a first embodiment of a demagnetization opening of an armature piece according to a preferred embodiment of the present invention; [Figure 5] FIG. 10 is a view showing a second embodiment of the demagnetization aperture of the armature piece according to the preferred embodiment of the present invention. [Figure 6] FIG. 10 is a diagram showing a third embodiment of the demagnetization openings of the armature pieces of the preferred embodiment of the present invention. [Figure 7] FIG. 10 is a view showing a fourth embodiment of the demagnetization openings of the armature pieces according to the preferred embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] Please refer to Figures 1 and 2, which are an exploded view and an assembled view, respectively, of an electromagnetic switch according to a preferred embodiment of the present invention. As shown in the figures, the magnetically attractive electromagnetic switch providing improved interruption speed according to the present invention comprises a coil assembly 1, a support frame assembly 2, a magnetic pole assembly 3, and a fixed contact assembly 4. The coil assembly 1 is used as an electromagnetic switch to generate magnetic attraction after power is supplied. It mainly includes an induction coil 10, which is formed by a winding method and has an iron core 12 wound around and wrapped around the induction coil 10 and positioned axially. Simply put, the magnetic circuit generated by the induction coil 10 after power is supplied forms a continuous magnetic field path with another metal conductor close to the iron core 12, and thus the iron core 12 can be attracted to the metal conductor.

[0011] The frame assembly 2 further comprises a fixed piece 20 and an elastic member 22, such as a spring or spring plate, of which at least one surface is mounted on the coil assembly 1 and a portion extends to form an extended end 201. Simply put, the fixed piece 20 and the coil assembly 1 are incompletely overlapped with each other, and the elastic member 22 is mounted on the fixed piece 20, with one end of the elastic member 22 fastened to the fixed piece 20. The fastening method can be, for example, a hook, ring, or other similar structure extending from the fixed piece 20 to fasten one end of the elastic member 22. The fixed piece 20 of the frame assembly 2 can also be bent, and the end portion is secured by inserting the iron core 12 through it.

[0012] Next, the magnetic pole assembly 3 is installed corresponding to the support frame assembly 2, and the magnetic pole assembly 3 has an armature piece 30 and a contact conducting member 32. After the coil assembly 1 is powered, the armature piece 30 is attracted by magnetic force and moves toward the iron core 12, while the contact conducting member 32 is fixed to one side of the armature piece 30, so that when the armature piece 30 is attracted by magnetic force, the contact conducting member 32 is synchronously operated. At least one movable contact 321 is provided on the contact conducting member 32, and the upper end 301 of the armature piece 30 is pivotally connected to the extended end 201 of the fixed piece 20 and fixed to the other end of the elastic member 22. Specifically, for example, grooves formed at the left and right ends of the armature piece 30 can be used to partially insert the extended end 201 and then pivotally connected to each other, thereby fixing the elastic member 22 at the middle position of the upper end 301 of the armature piece 30. Accordingly, when the coil assembly 1 is not energized, the armature piece 30 is positioned at the open position only by the tensile force of the elastic member 22. When the coil assembly 1 is energized, a magnetic attractive force is generated, which overcomes the tensile force of the elastic member 22 and causes the armature piece 30 to pivot toward the iron core 12 and be positioned at the closed position. Furthermore, there is a gap distance 90 between the armature piece 30 and the iron core 12, and when in the open position, the gap distance 90 gradually increases from the side of the upper end edge 301 where the armature piece 30 and the fixed piece 20 are pivotally connected to each other toward the side of the lower end edge 302 at the other end of the armature piece 30.

[0013] Furthermore, the fixed contact assembly 4 includes a base 40 and at least one fixed contact 421 provided on the base 40, and the base 40 serves to support and mount the coil assembly 1. The fixed contact 421 is disposed corresponding to the movable contact 321, and when the armature piece 30 is in the closed position, the movable contact 321 contacts the fixed contact 421 to establish electrical continuity. Of course, the base 40 may be modified and adjusted to have various grooves, holes, etc., depending on the shape, size, rigidity, and other specifications of the coil assembly 1 and the correspondingly connected support frame assembly 2 and magnetic pole assembly 3. Furthermore, since such modifications and adjustments do not particularly limit or affect the realization of the objectives of the present application, a repeated description thereof will be omitted here.

[0014] Furthermore, considering that the magnitude of the magnetic attraction force between the coil assembly 1 and the armature piece 30 is directly proportional to the cross-sectional area of ​​the armature piece 30, i.e., the larger the cross-sectional area of ​​the armature piece 30, the larger the coverage area of ​​its magnetic path, and the corresponding magnetic attraction force will be relatively greater. In light of this, the present application attempts to disrupt the integrity of the magnetic path on the armature piece 30, causing a disruption in the distribution of magnetic lines of force, thereby affecting the strength of the magnetic attraction force and achieving the goal of increasing the demagnetization rate and reducing the "disconnection time." Also referring to Figure 3, a diagram showing the demagnetization openings of an armature piece in an "experimental example" of the present invention is shown. In the "Experimental Example," at least one demagnetization aperture 303 is provided in the armature piece 30. However, even in the experimental example of the present application, when the position of the demagnetization aperture 303 is deflected toward one side of the pivot end edge between the armature piece 30 and the fixed piece 20, the armature piece 30 is pivoted relative to the fixed piece 20 and swung circumferentially. Therefore, it was found that the gap distance 90 exhibited in the open position gradually increases from the upper end edge 301 where the armature piece 30 is pivotally attached to the fixed piece 20 toward the lower end edge 302 at the other end of the armature piece 30. Furthermore, the size of the gap distance 90 is still inversely proportional to the square of the magnetic attraction force produced. In other words, when the gap distance 90 is at the end where the armature piece 30 and the iron core 12 are at their maximum distance, the magnetic attraction force is relatively small, but the influence is relatively large. Therefore, when the demagnetization opening 303 is opened as shown in Figure 3, the accompanying magnetic attraction force is significantly weakened, which affects the normal opening and closing operation of the armature piece 30 and the iron core 12. To maintain normal operation thereafter, it is necessary to increase the external power supply again to improve the magnetic attraction force, but this method is not intended by the present application.Therefore, as can be seen from the above experimental example, the normal operation of the armature pieces 30 and the iron core 12 is not affected, but the demagnetization time is shortened in order to destroy the integrity of the magnetic conduction path through the demagnetization openings 303. In this case, the armature pieces 30 of the present application are still provided with the demagnetization openings 303, but the demagnetization openings 303 are located on the opposing other ends of the pivotal mounting edges of the armature pieces 30 and the fixed pieces 20, as shown in Figure 4. Accordingly, by utilizing the above-mentioned conditions for providing the demagnetization openings 303, the effect of rapid demagnetization can be effectively achieved. Furthermore, the demagnetization opening 303 can still be prevented from being too close to the pivot end edge between the armature piece 30 and the fixed piece 20, thereby avoiding an influence on the magnetic attraction force. Furthermore, in the present invention, the demagnetization opening 303 can be limited to correspond to the clamping area 304 between the mapping positions of the armature piece 30 when the opposing other ends of the pivot end edges between the armature piece 30 and the fixed piece 20 are in the closed position, and the demagnetization opening 303 can be installed in the shape of a strip hole or a hat hole.

[0015] In addition, since the entire armature bar 30 swings and pivots relative to the iron core 12, its movement must be balanced. The placement of the demagnetization apertures 303 must also take into consideration symmetry, which disrupts the magnetic path, and avoids uneven magnetic attraction between the left and right sides of the armature bar 30, which could result in wear on the switch mechanism due to swinging over long periods of use. Therefore, the demagnetization apertures 303 are shaped symmetrically along a virtual mirror reference line 80 defined by the midpoint between the left and right ends of the armature bar 30, thereby preventing the above-mentioned problem from occurring. At the same time, the placement effect of the demagnetization apertures 303 should be such that it only affects the demagnetization effect, and the width of the bottom edge 302 of the armature bar 30 can be set smaller than the width of the top edge 301 of the armature bar 30. Accordingly, the magnetic attraction force between the armature piece 30 and the iron core 12 can be maintained at a relatively large value, regardless of whether the power supply is modulated, and the normal opening and closing operation of the electromagnetic switch can be maintained.

[0016] Next, reference is made to FIGS. 4 to 7, which show the installation position and embodiment of the demagnetization opening 303 of the armature piece 30 in a preferred embodiment of the present application. To strengthen confirmation of the position of the attraction point after the armature piece 30 is nearly close to the iron core 12, the armature piece 30 is further provided with a protruding point 60 on the same side as the demagnetization opening 303, and the protruding point 60 is located on the virtual mirror reference line 80. Accordingly, the installation of the protruding point 60 can further confirm the attraction position, preventing lateral displacement and vibration. Furthermore, once the attraction point position is confirmed using the protruding point 60, it is of course necessary to simultaneously consider the influence of the position of the protruding point 60 on any subsequent disruption of the magnetic path integrity. Accordingly, that is, by using the protrusion 60 to confirm the approximate attraction range, the shortest distance from the protrusion 60 to the bottom edge 302 of the armature piece 30 during installation is made smaller than or equal to the shortest distance from the demagnetization opening 303 to the bottom edge 302 of the armature piece 30. In this way, the demagnetization speed is substantially increased and the "breaking time" is reduced only after the magnetic conduction path provided by the demagnetization opening 303 is broken due to the above-mentioned installation condition restrictions.

[0017] Furthermore, as shown in FIG. 4, the demagnetization opening 303 has a strip-like hole shape extending from the imaginary mirrored reference line 80 toward the left and right of the armature piece 30. This destroys the consistency of the magnetic path, thereby increasing the demagnetization speed rate and shortening the "breaking time," without affecting the mutual attraction between the armature piece 30 and the iron core 12. Next, as shown in FIG. 5, the demagnetization opening 303 has a hat-shaped hole shape formed after being mirrored left and right about the imaginary mirrored reference line 80, and includes a hat edge groove 70 and a hat top groove 71, of which the hat top groove 71 is expressed as protruding toward the top edge 301 of the armature piece 30. Furthermore, as shown in FIG. 6, the hat top groove 71 protrudes in an arc shape, giving the demagnetization opening 303 an Ω-shaped hole shape. 7, the demagnetization apertures 303 are each composed of a plurality of parallel strip-shaped holes, and the distance between the strip-shaped hole that is aligned with the imaginary mirrored reference line 80 and the bottom edge 302 of the armature piece 30 is greater than the distance between the other strip-shaped holes and the bottom edge 302 of the armature piece 30. Therefore, the placement of the various demagnetization apertures 303 described above must all be located near the bottom edge 302 of the armature piece 30, and must be symmetrical based on the imaginary mirrored reference line 80. Furthermore, when the protrusion 60 is located, the distance between the protrusion 60 and the bottom edge 302 of the armature piece 30 must also comply with the conditional restriction on the distance. In practice, in order to meet the requirements of various different electrical equipment, it is sufficient that the demagnetization opening 303 can be opened in a manner that corresponds to the ``breaking time'' that the magnetic conduction path that should be naturally broken is intended to achieve, based on factors such as the area size of the armature piece 30.

[0018] In summary, in many magnetic attraction type electromagnetic switches, the armature piece 30 has one end pivotally mounted and swings under the action of magnetic force before and after energization to reach a suitable breaking speed; to achieve this purpose, one or more demagnetization apertures 303 may be provided at the non-pivot end of the armature piece 30, and the demagnetization apertures 303 may be, for example, stripe-shaped or hat-shaped. Of course, the demagnetization apertures 303 can be provided simply by being centrally or symmetrically mounted on the armature piece 30 to improve the balance of swing and further increase the product life. Therefore, even if the demagnetization apertures 303 are asymmetrically or eccentrically mounted, they can still achieve the effect of rapid breaking, which will be described here.

[0019] In summary, the magnetically attracted electromagnetic switch with improved interruption speed provided by the present invention, through the special structural design of the armature, can still maintain the strength of the opening and closing attractive force of the original electromagnetic switch at the same power supply level, and promote its normal operation. In other words, the present application provides an embodiment in which the demagnetization aperture and the corresponding aperture are installed at a specific position on the armature, or the relative installation conditions of the demagnetization aperture when the protrusion is installed, or the installation conditions of the width of the armature, etc., without substantially affecting the attractive holding force of the electromagnetic switch, can destroy the magnetic path area on the armature, thereby increasing the demagnetization speed and shortening the "interruption time," and can be used for various electrical devices that meet limit standards requiring rapid disconnection, such as those considered similar to energy storage equipment, and can effectively maintain the stability of their running operations. [Explanation of symbols]

[0020] 1 Coil assembly material 10 induction coil 12 Iron Core 2 Frame assembly members 20 Fixed piece 201 Stretched end 22 Elastic member 3 Magnetic pole assembly 30 armature piece 301 top edge 302 bottom edge 303 Demagnetization hole opening 304 Clamping area 32 Contact conducting member 321 Movable contact 4 Fixed contact assembly 40 pedestal 421 Fixed contact 60 convex point 70 Hat edge groove 71 Hat Top Open Groove 80 Virtual Mirror Reference Line 90 Gap distance

Claims

1. A magnetic attraction type electromagnetic switch having improved breaking speed, comprising: a coil assembly having an induction coil and an iron core located axially of the induction coil; a support frame assembly having a fixed piece and an elastic member; a magnetic pole assembly having an armature piece and a contact conducting member fixed to one side of the armature piece and operating synchronously; and a fixed contact assembly having a base for supporting and placing the coil assembly and at least one fixed contact provided on the base, the fixed piece has at least one surface mounted on the coil assembly member and a portion extending therefrom to form an extended end, the elastic member is mounted on the fixed piece, and one end of the elastic member is firmly connected to the fixed piece, the contact conducting member further has at least one movable contact, an upper end edge of the armature piece pivotally connected to the extended end of the fixed piece and fixedly connected to the other end of the elastic member, the armature piece being positioned at an open position by the action of a tensile force of the elastic member when the coil assembly member is in a non-energized state, and when the coil assembly member is in a powered state, a magnetic force is generated to pivot the armature piece toward the iron core and position the armature piece at a closed position, there is an air gap between the armature piece and the iron core, and the air gap when in the open position gradually increases from the side of the upper end edge where the armature piece is pivotally connected to the fixed piece toward the side of the lower end edge of the other end of the armature piece, the fixed contact is disposed corresponding to the movable contact, and when the armature piece is located at the closed position, the movable contact comes into contact with the fixed contact to establish a conductive state; A magnetically attracted electromagnetic switch having improved breaking speed, characterized in that at least one demagnetization aperture is provided in the armature piece, and the demagnetization aperture is located on the other end side of the pivot end side between the armature piece and the fixed piece, which faces each other.

2. 2. The magnetically attracting electromagnetic switch having improved breaking speed according to claim 1, wherein the demagnetization opening corresponds to a clamping area between mapping positions of the armature pieces when the opposing other ends of the pivot ends of the armature pieces and the fixed piece are located at the closed position.

3. 2. The magnetic attraction type electromagnetic switch for improving breaking speed according to claim 1, wherein the demagnetization opening is a stripe-shaped hole.

4. 2. The magnetic attraction type electromagnetic switch for improving breaking speed according to claim 1, wherein the demagnetization opening is hat-shaped.

5. 2. The magnetically attractive electromagnetic switch according to claim 1, wherein the demagnetization opening has a hole shape that is symmetrical with respect to a virtual mirror reference line defined by a midpoint between the left and right ends of the armature piece.

6. 6. The magnetic attraction type electromagnetic switch according to claim 5, wherein the demagnetization opening has a stripe-shaped hole shape extending from the virtual mirror reference line toward the left and right directions of the armature piece.

7. 6. The magnetically adsorbed electromagnetic switch having improved breaking speed according to claim 5, wherein the demagnetization opening has a hat-shaped hole shape formed after being mirrored laterally with respect to the virtual mirror reference line, and has a hat edge groove and a hat top groove, and the hat top groove is expressed so as to protrude toward the upper end edge of the armature piece.

8. 8. The magnetic attraction type electromagnetic switch having improved breaking speed according to claim 7, wherein the hat top groove protrudes in an arc shape, making the demagnetization opening an Ω-shaped hole.

9. 6. The magnetically attracting electromagnetic switch having improved breaking speed according to claim 5, wherein the demagnetization apertures are formed of a plurality of parallel strip-shaped holes, and the distance between the strip-shaped holes superimposed on the virtual mirror reference line and the lower edge of the armature piece is relatively large compared to the distance between the other strip-shaped holes and the lower edge of the armature piece.

10. 2. The magnetically adsorbed electromagnetic switch having improved breaking speed according to claim 1, wherein the armature piece further has a protruding point on the same side as the demagnetization opening, the protruding point being located on a virtual mirror reference line, and the shortest distance from the protruding point to the bottom edge of the armature piece is smaller than or equal to the shortest distance from the demagnetization opening to the bottom edge of the armature piece.

11. 11. The magnetically attracting electromagnetic switch for improving breaking speed according to claim 10, wherein the width of the lower end edge of the armature piece is smaller than the width of the upper end edge of the armature piece.

12. An armature piece for improving the interruption speed of a magnetically attracted electromagnetic switch, one end of which is pivotally mounted and which oscillates under the action of magnetic force before and after energization, characterized in that the non-pivot end of the armature piece has at least one demagnetization opening.

13. 13. The armature piece according to claim 12, wherein the demagnetization opening is in the form of a stripe hole.

14. 13. The armature piece according to claim 12, wherein the demagnetization opening is hat-shaped.

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