Coupling device

Abstract

Coupling device comprising a first coupling part with a first magnetic body and a first engagement section and a second coupling part with a second magnetic body and a second engagement section, wherein at least one of the first magnetic body and the second magnetic body comprises a permanent magnet, wherein the first engagement section and the second engagement section are configured such that they engage with each other, wherein the first coupling part and the second coupling part are configured such that, by means of a magnetic force in the direction of the magnetic adhesion generated between the first magnetic body and the second magnetic body when the first engagement section and the second engagement section are engaged with each other, a first magnetic adhesion surface of the first coupling part is in surface contact with a second magnetic adhesion surface of the second coupling part.wherein at least one section of the first engagement section of the first coupling part has a circular arc shape, wherein at least one section of the second engagement section of the second coupling part has a circular arc shape, wherein the first coupling part is rotatable with respect to the second coupling part when the first engagement section and the second engagement section are engaged with each other, and wherein the second engagement section of the second coupling part has a second inclined engagement surface which is inclined with respect to the direction of magnetic adhesion.

Description

BACKGROUND 1. TECHNICAL AREA The present disclosure relates to a coupling device. 2. STATE OF THE ART Mechanisms for coupling two items are commonly used in various applications, for example in the clothing, footwear, and industrial materials sectors. Among these, a coupling device that utilizes magnetic force—the force acting between magnets or between a magnet and a metal magnet body—can couple two items together through magnetic adhesion without requiring any manual intervention. In this respect, such a coupling device is extremely practical. US Patent 4,700,436 (Patent Document 1) is a prior art document disclosing such a coupling device utilizing magnetic force. The technology described in Patent Document 1 is already widely used as a magnetic coupling mechanism applied to the closure section of a bag or garment. The magnetic coupling mechanism from Patent Document 1 has an embodiment in which a first engagement element engages with a circular ferromagnetic body and a second engagement element engages with an annular magnet. A projection is provided at the center of the first engagement element. This projection is designed to be inserted into a hole at the center of the second engagement element.According to the magnetic coupling mechanism described in patent document 1, opening and closing is only possible by operation in the up-down direction (direction of magnetic release). Therefore, the coupling mechanism is advantageous in that it can be operated with a feel similar to that of a snap button. On the other hand, the engagement between the first and second engagement elements in the left-right direction (direction of the magnetic force surface), which is orthogonal to the up-down direction, depends solely on the mutual locking between the projection and the hole. Therefore, the disadvantage is that the engagement force in the left-right direction is not large and that in the up-down direction only the magnetic adhesion force, but no mechanical engagement force, is present. Another magnetic coupling mechanism is known, as described in US 2011 / 0265289 (Patent Document 2). The magnetic coupling mechanism from Patent Document 2 has an embodiment in which one engagement element with a circular arc-shaped outer edge and another engagement element with a circular arc-shaped groove in its inner surface are coupled to one another by a magnet. The coupling mechanism from Patent Document 2 is described in detail with reference to Figures 26A and B, as well as Figures 27A and B. The coupling mechanism of Patent Document 2 has an embodiment in which a first engagement element 511 and a second engagement element 512 are coupled to one another by the magnetic force of magnets 521 and 522. The first engagement element 511 comprises a convex engagement section 513, which is a flat plate section with a circular arc-shaped outer edge.The second engagement element 512 comprises a concave engagement section 514 with a circular arc-shaped groove bounded on its inner surface. In this coupling mechanism, the circular arc-shaped flat plate section of the convex engagement section 513 engages in the circular arc-shaped groove of the concave engagement section 514. This causes the convex engagement section 513 and the concave engagement section 514 to engage with each other. Therefore, the coupling mechanism possesses a high mechanical engagement force in both the up-down and left-right directions. Furthermore, the coupling mechanism is designed such that the first engagement element 511 and the second engagement element 512 can be rotated relative to each other. In this respect, this coupling mechanism is advantageous. SUMMARY A coupling device according to the present embodiment comprises a first coupling part with a first magnetic body and a first engagement section, and a second coupling part with a second magnetic body and a second engagement section, wherein at least one of the first magnetic body and the second magnetic body comprises a permanent magnet, wherein the first engagement section and the second engagement section are configured such that they engage with each other, and wherein the first coupling part and the second coupling part are configured such that a magnetic force in the direction of the magnetic adhesion, which is generated between the first magnetic body and the second magnetic body when the first engagement section and the second engagement section are engaged with each other,a first magnetic adhesion surface of the first coupling part is in surface contact with a second magnetic adhesion surface of the second coupling part, wherein at least one section of the first engagement section of the first coupling part has a circular arc shape, wherein at least one section of the second engagement section of the second coupling part has a circular arc shape, wherein the first coupling part is rotatable with respect to the second coupling part when the first engagement section and the second engagement section are in engagement with each other, and wherein the second engagement section of the second coupling part has a second inclined engagement surface which is inclined with respect to the direction of the magnetic adhesion. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a perspective view of a coupling device 10 according to the present embodiment (first embodiment) in a release state. Fig. 2 is a perspective view of the coupling device 10 according to the present embodiment in a coupled state. Fig. 3 is a top view of the coupling device 10 according to the present embodiment in the coupled state. Fig. 4 is a bottom view of the coupling device 10 according to the present embodiment in the coupled state. Fig. 5 is a left side view of the coupling device 10 according to the present embodiment in the coupled state. Fig. 6 is a front view of the coupling device 10 according to the present embodiment in the coupled state. Fig. 7 is a sectional view at AA-AA from Fig. 5. Fig. 8 is a perspective view of a first coupling part (plug) 11 used in the present embodiment.Figure 9 is a side view of the first coupling part (plug) 11 used in the present embodiment. Figure 10 is a perspective view of a second coupling part (socket) 31 used in the present embodiment, viewed from below. Figure 11 is a perspective view of the second coupling part (socket) 31 used in the present embodiment, viewed from above. Figure 12 is a top view of the second coupling part (socket) 31 used in the present embodiment. Figure 13 is a left side view of the second coupling part (socket) 31 used in the present embodiment. Figure 14 is a rear view of the second coupling part (socket) 31 used in the present embodiment. Figure 15 is a sectional view of BA-BA from Figure 14. Fig. 16 is a sectional view of CA-CA from Fig. 6.Figure 17 is an illustrative view of a state in which the first coupling part (plug) 11 has been operated in the release direction from the state of Figure 16. Figure 18 is an illustrative view of a state in which the first coupling part (plug) 11 has been operated further in the release direction from the state of Figure 17. Figure 19 is an illustrative view of the operation of a coupling mechanism applied to the present embodiment (plug and socket meeting in an up-down direction). Figure 20 is an illustrative view of the operation of a coupling mechanism applied to the present embodiment (plug and socket after a reset slide operation). Figure 21 is a top view of a second coupling part (socket) 31B used in a further embodiment (second embodiment), serving to illustrate a further embodiment.Figure 22 is a top view of a second coupling part (socket) 31C used in a further embodiment (third embodiment), serving to illustrate a further embodiment (third embodiment). Figure 23 is a left side view of the second coupling part (socket) 31C used in the third embodiment. Figure 24 is a perspective view of the second coupling part (socket) 31C used in the third embodiment, viewed from below. Figure 25 is a left side view of a second coupling part (socket) 31D used in a further embodiment (fourth embodiment), serving to illustrate a further embodiment (fourth embodiment). Figures 26A and 26B are views to illustrate the operation of a prior art coupling mechanism. Figure 26A shows the state of two engagement elements at the beginning of the coupling operation. Figure 26B shows the two engagement elements in the coupled state. Fig.Figures 27A and 27B are views illustrating the operation of a prior art coupling mechanism. Figure 27A shows two engagement elements meeting in an up-down direction. Figure 27B shows the two engagement elements after a return slide operation. DETAILED DESCRIPTION The coupling mechanism of patent document 2 has the advantage described above. However, unlike the coupling mechanism of patent document 1 described above, this coupling mechanism has the disadvantage that operation with a feel similar to that of a snap button is difficult. With the magnetic coupling mechanism from patent document 2, the first engagement element 511 is first brought into the position shown in Fig. 26A. Then, the first engagement element 511 is moved in the left-right direction by magnetic force or operating force. This achieves the engagement state shown in Fig. 26B. If an attempt is now made to engage the two engagement elements solely by operating them in the up-down direction, as with a snap button, then, as shown in Fig.Figure 27A shows the lower surface 515 of the first engagement element 511 against the upper surface of a flange 516, which defines the arcuate groove of the second engagement element. Even if further attempts are made to press the first engagement element 511 in an up-down direction, it does not overcome the flange 516. Therefore, the first engagement element 511 is temporarily moved back to one side in a left-right direction to the position shown in Figure 27B. Subsequently, the first engagement element 511 is moved in the opposite direction. Thus, such a "return sliding action" is required.A corner section 517 of the circular arc-shaped flat plate section of the first engagement element 511 and a corner section 518 of the flange both have an essentially right-angled cross-sectional shape (meaning that, despite a chamfering process on both corner sections necessitated by the mechanical design, an orthogonal corner section is defined by one surface and the other). Therefore, the coupling mechanism of patent document 2 has a structure in which the first engagement element 511 can only move downwards once, during this "return sliding operation," the corner section 517 of the first engagement element has completely overcome the corner section 518 of the flange. Furthermore, the first engagement element 511 is typically covered, for example, by a top surface material 523 of the closure section of a bag.Therefore, an operator cannot discern the positional relationship between the convex engagement section 513 and the concave engagement section 514. In this state, the "reset slide operation" must be performed manually. In this respect, the user-friendliness of the coupling mechanism of patent document 2 leaves much to be desired. The present disclosure addresses the circumstances described above. The objective of this disclosure is to provide a coupling device with a magnetic coupling mechanism that is highly user-friendly in both engagement and disengagement. Furthermore, the objective of this disclosure is to provide a coupling device suitable for high mass production, comprising a coupling element with a mold that can be injection molded using only an upper and a lower mold half. A coupling device 10 according to the present embodiment therefore comprises a first coupling part 11 with a first magnetic body 21 and a first engagement section 14 and a second coupling part 31 with a second magnetic body 41 and a second engagement section 34, wherein at least one of the first magnetic body 21 and the second magnetic body 41 comprises a permanent magnet, wherein the first engagement section 14 and the second engagement section 34 are configured such that they engage with each other, wherein the first coupling part 11 and the second coupling part 31 are configured such that a magnetic force in the direction of the magnetic adhesion, which is generated between the first magnetic body 21 and the second magnetic body 41 when the first engagement section 14 and the second engagement section 34 are engaged with each other,a first magnetic adhesion surface 16 of the first coupling part 11 is in surface contact with a second magnetic adhesion surface 36 of the second coupling part 31, wherein at least one section of the first engagement section 14 of the first coupling part 11 has a circular arc shape, wherein at least one section of the second engagement section 34 of the second coupling part 31 has a circular arc shape, wherein the first coupling part 11 is rotatable with respect to the second coupling part 31 when the first engagement section 14 and the second engagement section 34 are engaged with each other, and wherein the second engagement section 34 of the second coupling part 31 has a second inclined engagement surface 43 which is inclined with respect to the direction of the magnetic adhesion. In the coupling device 10 of the present embodiment, a projection section 51 can be provided on the second coupling part 31 on the side opposite the second engagement section 34, wherein a circular arc center of at least one section of the circular arc-shaped second engagement section 34 lies between them, and at least one section of the projection section 51 can have a circular arc shape. In the coupling device 10 of the present embodiment, the first coupling part 11 can also include a first foot section 12 in the form of a flat plate, wherein, when, during operation to release the first coupling part 11 from the second coupling part 31, a first magnetic force adhesion surface 16 of the first coupling part 11 rests on the projecting section 51 of the second coupling part 31, the first foot section 12 is not in contact with the second engagement section 34 of the second coupling part 31. In the coupling device 10 of the present embodiment, a linear guide section 55 can be provided on the second coupling part 31 between the second engagement section 34 and the projection section 51. In the coupling device 10 of the present embodiment, at least one section of the first engagement section 14 having a circular arc shape can have a first inclined engagement surface 23, wherein the first inclined engagement surface is inclined with respect to the direction of the magnetic adhesion. In the coupling device 10 of the present embodiment, the second coupling part 31 can have a second upper engagement surface 45 on the upper surface of the second engagement section 34, the first coupling part 11 can include a first foot section 12 in the form of a flat plate, the first foot section 12 can be provided extending further downwards in relation to the first engagement section 14, and a first gap d1 between the first foot section 12 of the first coupling part 11 and the second engagement section 34, when the first coupling part 11 and the second coupling part 31 are engaged with each other, can be greater than 5% of a total thickness D in the top-bottom direction of the coupling device 10. In the coupling device 10 of the present embodiment, an opening hole 61 can be provided on the second engagement section 34, which extends in the direction of the magnetic adhesion. In the coupling device of the present embodiment, the second coupling part 31 can have a second upper engagement surface 45 on an upper surface of the second engagement section 34, a projecting section end surface 57A can be provided on the two end sections of the second engagement section 34, the projecting section end surface 57A can have an inclined surface that slopes down from the second upper engagement surface 45, and a curved projecting section displacement surface 57B can be provided between the projecting section end surface 57A and the second inclined engagement surface 43. In the coupling device 10 of the present embodiment, when viewed in the direction of magnetic adhesion, the distance from a center point C of a radius of curvature at a left-right central position of the second engagement section 34 to a defined edge section of the curved projection section displacement surface 57B on the second coupling part 31 can be greater than the radius of curvature. In the coupling device 10 of the present embodiment, a protrusion section radius change surface 71 can be provided between the curved protrusion section displacement surface 57B and the second inclined engagement surface 43, and on the second coupling part 31, when viewed in the direction of magnetic adhesion, a distance from the center point C to a defined edge section of the protrusion section radius change surface 71 can be greater than the radius of curvature. In the coupling device 10 of the present embodiment, an interruption section 75 can be provided between the second engagement section 34 and the projection section 51, and the projection section 51 can be reduced in thickness at the interruption section 75 in the direction of magnetic adhesion. In the coupling device 10 of the present embodiment, the second coupling part 31 can have the second upper engagement surface 45 on the upper surface of the second engagement section 34, and the second upper engagement surface 45 can have an inclined surface that lowers in the release direction of the coupling device 10. According to the coupling device of the present embodiment, the coupled coupling parts can be rotated relative to each other. Furthermore, a magnetic coupling device is provided, which is highly user-friendly in both engagement and disengagement. Another advantage of the coupling device according to the present embodiment is that the coupling parts contained in the coupling device can be injection molded using only an upper and a lower mold half. Therefore, a coupling device with high mass production capability can be provided. Design of the present embodiment: The present embodiment is described in detail below with reference to the figures. The present embodiment is not limited by the embodiments described below. For the following description, the operating directions of the coupling device 10, a first coupling part (plug) 11 and a second coupling part (socket) 31 are defined, for the sake of simplicity, as a coupling release direction (X-axis direction), a left-right direction (Y-axis direction) and an up-down direction (Z-axis direction) as follows. In a top view of the coupling device 10 shown in Fig. 3, as indicated by the arrows in Fig. 3, the direction in which the first coupling part 11 and the second coupling part 31 are coupled or released is defined as the "coupling release direction (X-axis direction)." The direction in which the first coupling part 11 and the second coupling part 31 are coupled is defined as the "coupling direction (positive direction of the X-axis)." The direction in which the coupling between the first coupling part 11 and the second coupling part 31 is released is defined as the "release direction (negative direction of the X-axis)." In a top view of the coupling device 10 shown in Fig. 3, as indicated by the arrows in Fig. 3, a direction orthogonal to the "coupling release direction (X-axis direction)" is defined as the "left-right direction (Y-axis direction)." For simplicity, the upward direction in the plane of the paper in Fig. 3 is defined as the "left direction (positive direction of the Y-axis direction)." The downward direction in the plane of the paper in Fig. 3 is defined as the "right direction (negative direction of the Y-axis direction)." The XY plane can also be understood as the plane in which a first magnetic force adhesion surface 16, described below, is in surface contact with a second magnetic force adhesion surface 36 when the coupling device 10 is in the coupled state. In the side view of the coupling device 10 shown in Fig. 5, as indicated by the arrows in Fig. 5, a direction orthogonal to the "coupling release direction (X-axis direction)" is defined as the "up-down direction (Z-axis direction)." For simplicity, the upward direction in the plane of the paper in Fig. 5 is defined as the "upward direction (positive direction of the Z-axis direction)." The downward direction in the plane of the paper in Fig. 5 is defined as the "downward direction (negative direction of the Z-axis direction)." The "up-down direction (Z-axis direction)" can also be understood here as the direction orthogonal to the XY plane. In the following description, the "up-down direction (Z-axis direction)" is also referred to as the "direction of the release of the magnetic adhesion." In this case, the “negative direction of the Z-axis direction (downward direction)” is the “direction of magnetic adhesion”.The “positive direction of the Z-axis direction (upward direction)” is the “direction of separation of the magnetic force”. Fig. 1 is a perspective view of the coupling device 10 of the present embodiment (first embodiment) in the released state. Figs. 2, 3, 4, 5, 6 to 7 are views showing the coupling device 10 of the present embodiment in the coupled state. Fig. 2 is a perspective view of the coupling device 10 in the coupled state. Fig. 3 is a top view. Fig. 4 is a bottom view. Fig. 5 is a left side view. The right side view is symmetrical to the left side view. Fig. 6 is a front view. Fig. 7 is a sectional view at AA-AA from Fig. 5. The coupling device 10 comprises a first coupling part 11 and a second coupling part 31. The first coupling part 11 can also be referred to here as a "plug." The second coupling part 31 can also be referred to as a "socket." In the following description, the present embodiment is described using the terms "plug" and "socket" simultaneously for better understanding. First, the design elements that fulfill the basic function of coupling are described in broad outline. The first coupling part 11 includes a first engagement section 14, which generates a mechanical engagement force. The second coupling part 31, in turn, includes a second engagement section 34, which is mechanically brought into engagement with the first engagement section 14.Furthermore, the first coupling element 11, as a design element that generates a magnetic attraction force in addition to the mechanical engagement force, comprises a first magnetic body 21. The second coupling element 31 further comprises a second magnetic body 41. At least one of the first magnetic body 21 and the second magnetic body 41 is a permanent magnet. The other can be a ferromagnetic body that is not a permanent magnet. In the embodiment described below, the example is given in which both are permanent magnets. Next, the coupling operation is described in broad terms. When the first coupling element 11, in a state in which it can be coupled to the second coupling element 31, is brought close to the second coupling element 31, an attraction force arises between the first magnetic body 21 and the second magnetic body 41 due to magnetic force.The first engagement section 14 and the second engagement section 34 are guided by this attractive force and mechanically engaged with each other. This mechanical engagement prevents the first coupling part 11 and the second coupling part 31 from simply being moved in any of the directions: "Coupling direction (in the positive direction of the X-axis)," "Left-right direction (Y-axis)," and "Up-down direction (Z-axis)." The first coupling part 11 and the second coupling part 31 are both made of plastic and are manufactured by injection molding. Examples of the plastic materials used include thermoplastics such as polyamide, polyacetal, polypropylene, polyethylene terephthalate, polyethylene, ABS, and polybutylene terephthalate (PBT). The range of usable plastic materials is not limited to these examples. The fine structure of the first coupling part 11 and the second coupling part 31 will now be described in more detail. Design of the first coupling part (plug) 11 Fig. 8 is a perspective view of the first coupling part (connector) 11 used in the present embodiment. Fig. 9 is a side view of the first coupling part (connector) 11. The detailed structure of the first coupling part 11 will now be described in more detail, with reference to Figs. 1, 2, 3, 4, 5, 6 to 7, as well as to Figs. 8 and 9. As shown in Fig. 8, the first coupling part 11 comprises a first foot section 12, a first engagement receiving section 13, and a first engagement section 14. In the present embodiment, the first foot section 12 is a circular plate with a circular outer circumference. The circular plate has a flat plate section 28 on its outer circumferential side. At the first coupling part 11, the thickness is smallest at the flat plate section 28 in the top-bottom direction.Inwardly, a stepped section 27 is provided within the flat plate section 28. The stepped section 27 has a circular outer circumference. The stepped section 27 has a suitable thickness in the "top-bottom direction". The back side of the flat plate section 28 (top side in the Z-axis direction) forms a first mounting surface 18. The first coupling element 11 is attached to the first mounting surface 18, for example, to the fabric of a bag or garment. In the present embodiment, the flat plate section 28 is sufficiently thin and flexible. Therefore, the first coupling element (connector) 11 is designed such that by bringing the first mounting surface 18 into contact with the fabric of a bag or garment, the flat plate section 28 and the fabric of the bag or garment can be sewn together by a sewing machine.The first coupling part (plug) 11 can also be attached to the fabric of a bag or garment by means of an adhesive or bonding agent that is attached to the first attachment surface 18. In the present embodiment, the stepped section 27 is also provided. If both the stepped section 27 and the flat plate section 28 are provided, a more advantageous design can be achieved with regard to ease of attachment to fabric and user-friendliness. However, the stepped section 27 is not mandatory. The first foot section 12 can be formed solely by the flat plate section 28. Furthermore, the shape of the first foot section 12 need not be circular. The first foot section 12 can have a desired shape, such as essentially a rectangle. The first engagement section 13 is provided inside the step section 27 of the first foot section 12. The first engagement section 13 has an axis extending approximately in the top-bottom direction and the shape of a thin round cylinder. The first engagement section 14 is provided on the underside of the first engagement section 13 (underside in the Z-axis direction). In Figures 8 and 9, the first coupling part 11 is shown such that the orientation of the "Z-axis direction (top-bottom direction)" is reversed compared to Figure 5. At least part of the first engagement section 14 has a circular arc shape. This allows the first coupling part 11 to be rotated relative to the second coupling part 31 when the first engagement section 14 and the second engagement section 34 are engaged with each other. The first intervention section 14 comprises a first inclined intervention surface 23 and a first intervention surface 24.A first magnetic force adhesion surface 16 is provided on the underside of the first engagement section 14 (underside in the Z-axis direction). This first magnetic force adhesion surface 16 is a surface that is substantially orthogonal to the "top-bottom direction" (Z-axis direction or "direction of magnetic release"). A "substantially orthogonal" surface does not necessarily mean only a surface that is exactly 90 degrees orthogonal. "Substantially orthogonal" means that it includes both the case where a certain inclination is provided, i.e., a certain inclination in the "coupling release direction (X-axis direction)" on the first magnetic force adhesion surface 16, and the case where a design flaw is present. This also applies when the term "substantially orthogonal" is used in the following text. The first engagement surface 24 extends from an end section of the outer circumferential edge of the first engagement receiving section 13 (end section on the underside in the Z-axis direction) further towards the outer circumferential side and parallel to the XY plane. The first engagement surface 24, the first engagement receiving section 13, and the first foot section 12 define a space (a concave section extending circumferentially) into which a second engagement section 34 of the second coupling part (socket) 31 described below is inserted. The first inclined engagement surface 23 extends from the outer circumferential side of the first engagement surface 24 towards the inner circumferential side. The shape of the first inclined engagement surface 23 is, for example, a section of the side face of a cone whose axis is the central axis of the first coupling part 11. As shown in Fig. 9, when viewed from the side, the first inclined engagement surface 23 is inclined at a defined angle (40 degrees to 80 degrees, preferably 45 degrees) with respect to the "top-bottom direction" (Z-axis direction or "direction of magnetic release") of the first coupling part 11. As another way of describing the first inclined engagement surface 23, the first inclined engagement surface 23 extends upwards (positive direction of the Z-axis) from the center of the circular arc, increasing in a radial direction. The first inclined engagement surface 23 can be a flat surface or a curved surface. The first inclined engagement surface 23 is not a machining section, as described in patent document 2, formed by chamfering a corner section, which is a common feature necessitated by the mechanical design. The first inclined engagement surface 23 is a surface that exists separately from a chamfering machining section located between the chamfering machining section of one corner section and the chamfering machining section of another corner section.The first magnetic force adhesion surface 16 is arranged further towards the inner circumference with respect to the edge section on the inner circumferential side of the first inclined engagement surface 23. The first magnetic force adhesion surface 16 is a surface which, in the coupling state of the coupling device 10, is in surface contact with a second magnetic force adhesion surface 36 of the second coupling part (socket) 31 described below. As shown in Fig. 8, the first magnetic force adhesion surface 16 is a circular, flat surface. A first concave gate section 29 is provided in its central section. A sprue is located on the first concave gate section 29, through which the molten plastic is injected into the mold during the production of the first coupling part 11 by injection molding. The sprue distributor of the sprue is separated at the first concave gate section 29.By providing the first concave sprue section 29 as in the present embodiment, even if part of the sprue distributor breaks off and remains, the surface contact between the first magnetic force adhesion surface 16 and the second magnetic force adhesion surface 36 is not impaired by the broken-off and remaining sprue distributor. In a boundary section between the first inclined engagement surface 23 and the first engagement surface 24 and in a boundary section between the first inclined engagement surface 23 and the first magnetic force adhesion surface 16, a known surface chamfering process (without reference numeral) is carried out in the present embodiment, which is dictated by the mechanical design. On the reverse side of the first coupling part 11 (top side in the Z-axis direction), a first hole section 19 is provided, as shown in Figs. 1, 2 to 3. The first magnetic body (first magnet) 21 is fixed inside the first hole section 19. The first hole section 19 is positioned further on the inner circumference than the first base section 12. The first hole section 19 is a hole with a circular base. The first magnetic force adhesion surface 16 is arranged on the reverse side of the base of the hole (bottom side in the Z-axis direction). In the present embodiment, the first base section 12 includes the step section 27. Therefore, a recessed area for the step section 27 is arranged around the first hole section 19. The first magnetic body (first magnet) 21 is attached inside the first hole section 19 by any suitable means, such as crimping or gluing.In the present embodiment, for the sake of simplicity, the description is such that the first magnetic body (first magnet) 21 is visible at the first hole section 19. However, the first magnetic body (first magnet) 21 can also be arranged in the first hole section 19 by means of a cover element provided at the first hole section 19 or by resin poured into the first hole section 19 in such a way that it is not visible (does not readily detach from the first hole section 19). Design of the second coupling part (socket) 31. Figures 10, 11, 12, 13, 14 to 15 are illustrative views of the design of the second coupling part (socket) 31. Figure 10 is a perspective view of the second coupling part (socket) 31 used in the present embodiment, viewed from below. Figure 11 is a perspective view of the second coupling part 31, viewed from above. Figure 12 is a top view of the second coupling part 31. Figure 13 is a left side view of the second coupling part 31. Figure 14 is a rear view of the second coupling part 31. Fig. 15 is a sectional view of BA-BA from Fig. 14 (where Fig. 15 can also be described as a section of a symmetry mid-surface in the left-right direction of the second coupling part 31). The fine structure of the second coupling part 31 is now described in more detail, with reference to Figs. 1, 2, 3, 4, 5, 6 to 7, and also to Figs. 10, 11, 12, 13, 14 to 15. In the embodiment shown in Fig. 10, the second coupling part 31 comprises a second foot section 32, which is an element that essentially has the form of a flat plate. Above the second foot section 32, a functional part is also arranged, which includes the second engagement section 34 and a projecting section 51. In the present embodiment, the second foot section 32 is essentially square. As shown in Fig. 11, a second mounting surface 38 is formed on the rear side of the second foot section 32 (underside in the Z-axis direction). The second coupling part 31 is attached to the second mounting surface 38, for example, to the fabric of a bag or garment. In the present embodiment, the second foot section 32 is sufficiently thin and flexible. Therefore, the second coupling part (socket) 31 is designed such that by bringing the second mounting surface 38 into contact with the fabric of a bag or garment, the second foot section 32 and the fabric of the bag or garment can be sewn together by a sewing machine. In particular, in the present embodiment, part of the second foot section 32 forms a thin-walled section 47.The thickness of the thin-walled section 47 in the "top-bottom direction" is less than that of the other parts. In this way, the second foot section 32 is designed such that a sewing thread can be more easily sewn to the thin-walled section 47. The second coupling part (socket) 31 can also be attached to the fabric of a bag or garment by means of an adhesive or glue that is attached to the second attachment surface 38. Furthermore, the thin-walled section 47 does not necessarily have to be provided. In addition, the outer circumference of the second foot section 32 is not limited to a square shape. The outer circumference can be a desired shape, such as essentially a circle. On one side of the second coupling part 31 (the side in the "positive direction of the X-axis"), the outer circumferential engagement surface 35 is arranged such that it projects upwards from the second foot section 32. On the other side of the second coupling part 31 (the side in the "negative direction of the X-axis"), the projection section (the section opposing the movement) 51 is arranged such that it projects upwards from the second foot section 32. In the present embodiment, the second coupling part 31 is designed such that the outer circumferential engagement surface 35 and the projection section 51 form a substantially circular projecting portion. However, in the present embodiment, the outer circumferential engagement surface 35 and the projection section 51 are not continuously connected to each other. A linear guide section 55 is provided between them.In this way, the outer circumferential engagement surface 35, the projecting section 51, and the linear guide section 55 preferably form a substantially circular projecting part with a total circumference continuous through 360 degrees. However, these design elements do not necessarily have to be continuously connected to each other over the entire circumference of the projecting part. An outer circumferential engagement surface 35 and the projecting section 51 can each form a circular arc-shaped part with an inner circumferential angle of less than 90 degrees. The linear guide section 55 is also not necessarily required. Next, the design of the side of the second coupling part 31, on which the outer circumferential engagement surface 35 is provided (side in the “positive direction of the X-axis direction”), will be described in detail. As clearly shown in the sectional view of Fig. 15, the second engagement section 33 and the second engagement section 34 are provided on the inner circumferential side of the outer circumferential engagement surface 35. At least a portion of the second engagement section 34 has a circular arc shape. At least a portion of the second engagement section 33 also has a circular arc shape. By having at least a portion circular arc-shaped, the first coupling part 11 can be rotated relative to the second coupling part 31 when the first engagement section 14 and the second engagement section 34 are engaged. The second engagement section 34 further comprises three surfaces: a second inclined engagement surface 43, a second lower engagement surface 44, and a second upper engagement surface 45. The second upper engagement surface 45 extends from the upper end section of the outer circumferential engagement surface 35 towards the inner circumferential side.The second upper engagement surface 45 is essentially orthogonal to the "top-bottom direction (Z-axis direction)". The second inclined engagement surface 43 extends continuously from the inner circumferential edge of the second upper engagement surface 45. The shape of the second inclined engagement surface 43 is, for example, a section of the side face of a cone whose axis is the central axis of the second coupling part 31. Since the second inclined engagement surface 43 has the cross-sectional surface illustrated in Fig. 15 (cross-sectional surface containing the symmetry center surface in the left-right direction of the second coupling part 31), it is a surface inclined at a defined angle (40 degrees to 80 degrees, preferably 45 degrees) with respect to the "top-bottom direction" (Z-axis direction or "direction of magnetic release"). As another way of describing the second inclined engagement surface 43, the second inclined engagement surface 43 extends upwards (positive direction of the Z-axis) from the center of the circular arc increasingly in the radial direction. The second inclined engagement surface 43 can be a flat surface or a curved surface. The second inclined engagement surface 43 is not a machining section, as described in patent document 2, which is formed by chamfering a corner section, a common feature necessitated by the mechanical design. The second inclined engagement surface 43 is a surface that exists separately from a chamfering machining section located between the chamfering machining section of one corner section and the chamfering machining section of another corner section.The second lower engagement surface 44 extends from the inner circumferential edge (lower end edge) of the second inclined engagement surface 43 such that it forms an acute angle with the second inclined engagement surface 43 (an angle at which the second lower engagement surface 44 projects towards the inner circumferential side). The second lower engagement surface 44 extends from the inner circumferential edge (lower end edge) of the second inclined engagement surface 43 in the direction of the outer circumference and is essentially orthogonal to the "top-bottom direction (Z-axis direction)." The second engagement receiving section 33 is provided on the underside of the second engagement section 34. As shown in Fig. 15, the inner circumferential surface of the second engagement receiving section 33 extends downwards from the outer circumferential edge of the second lower engagement surface 44.The second lower engagement surface 44 and the inner circumferential surface of the second engagement receiving section 33 define a space (a concave section extending circumferentially) into which the first engagement section 14 of the first coupling part (plug) 11 is inserted. As illustrated in Fig. 12, the shape of the second engagement section 34, when viewed from the downward direction of the second coupling part 31, is a semicircular arc. Here, the arc has an inner circumferential angle of 170 degrees or more, 190 degrees or less, and preferably 180 degrees. At both end sections of the second engagement section 34, a projecting section end surface 57A is provided to guide the movement of the first coupling part 11, so that the first coupling part 11 easily engages during coupling. As shown in Figs. 12 and 13, the projecting section end surface 57A forms a slope that descends from the second upper engagement surface 45 in a downward direction. A curved projecting section displacement surface 57B is also provided between the projecting section end surface 57A and the second sloped engagement surface 43.This curved projection section displacement surface 57B is a curved surface provided for a smooth, continuous connection between the projection section end surface 57A and the second inclined engagement surface 43. When the coupling device 10 is coupled, the first engagement section 14 of the first coupling part 11 is guided along the projection section end surface 57A and the curved projection section displacement surface 57B in accordance with the second engagement section 34. Therefore, the coupling operation of the coupling device 10 is simple. For descriptive purposes, the projection section end surface 57A and the curved projection section displacement surface 57B are shown as separate design elements from the second inclined engagement surface 43.However, the projecting section end surface 57A and the curved projecting section displacement surface 57B also include parts that can engage with the first engagement section. In this sense, the projecting section end surface 57A and the curved projecting section displacement surface 57B can also be understood as parts of the second inclined engagement surface 43. In the following description, the projecting section end surface 57A and the curved projecting section displacement surface 57B are described as separate design elements from the second inclined engagement surface 43. Next, the design of the side of the second coupling part 31 on which the projecting section (the section opposing the movement) 51 is provided (side in the "negative direction of the X-axis") is described in detail. As shown in Figs. 10 and 12, the projecting section 51 is provided on the side of the second coupling part 31 opposite the second engagement section 34, with the center of the circular arc of the previously described circular arc of the second engagement section 34 lying between them. At least one portion of this projecting section 51 has a circular arc shape. As clearly shown in the sectional view of Fig. 15, the projecting section 51 comprises an inclined projecting surface 52, an upper projecting surface 53, and a projecting section outer circumferential surface 58. The projecting section outer circumferential surface 58 is arranged such that it extends upwards from the second foot section 32.The upper projection surface 53 extends from the edge section on the side of the upper end of the projection section's outer circumferential surface 58 towards the inner circumferential side. The upper projection surface 53 is essentially orthogonal to the "top-bottom direction (Z-axis direction)." The inclined projection surface 52 extends continuously from the inner circumferential edge of the upper projection surface 53. The shape of the inclined projection surface 52 is, for example, a section of the side face of a cone whose axis is the central axis of the second coupling part 31. Since the inclined projection surface 52 has the cross-sectional surface illustrated in Fig. 15 (cross-sectional surface containing the left-right symmetry center surface of the second coupling part 31), it is inclined at a defined angle with respect to the "top-bottom direction" (Z-axis direction or direction of magnetic release). This fixed angle can be set to 90 degrees or less.A preferred angle is 45 degrees. When the first coupling part 11 is released from the second coupling part 31, the projecting section 51 contacts the first coupling part 11. The projecting section 51 serves to generate a resistance force caused by this contact. By adjusting the height of the projecting section 51, the operating feel when releasing the first coupling part 11 from the second coupling part 31 can be adjusted. The second magnetic contact surface 36 is provided between the projecting section 51 and the second engagement section 34. The second magnetic contact surface 36 is a surface that, in the coupled state of the coupling device 10, is in surface contact with the first magnetic contact surface 16 of the first coupling part (plug) 11. As shown in Fig. 12, the second magnetic contact surface 36 is a substantially circular, flat surface. A second concave gate section 49 is provided in its circular central section. The sprue distributor is separated from the second concave gate section 49 during the production of the second coupling part 31 by injection molding, just as it is from the first concave gate section 29 already described.Therefore, even if part of the sprue distributor breaks off and remains, the surface contact between the first magnetic force adhesion surface 16 and the second magnetic force adhesion surface 36 is not impaired by the broken-off and remaining sprue distributor. On the reverse side of the second coupling part 31 (underside in the Z-axis direction), a second hole section 39 is provided, as shown in Figs. 4 and 11. The second magnetic body (second magnet) 41 is fixed inside the second hole section 39. The second hole section 39 is arranged on the inner circumferential side of the second base section 32 and has a circular base. The second magnetic force attachment surface 36 is arranged on the reverse side of the base surface of the second hole section 39 (top side in the Z-axis direction). The second magnetic body (second magnet) 41 is attached inside the second hole section 39 by any suitable means, such as crimping or gluing. In the present embodiment, for the sake of simplicity, the description is given such that the second magnetic body (second magnet) 41 is shown at the second hole section 39.However, the second magnetic body (second magnet) 41 can also be arranged in the second hole section 39 by means of a cover element provided at the second hole section 39 or a resin poured into the second hole section 39 in such a way that it is not visible (does not easily detach from the second hole section 39). As shown in Figs. 4 and 11, an opening 61 and a recessed section 62 are provided on the rear side of the second coupling part 31. The second lower engagement surface 44 is also arranged on the underside of the arc-shaped second engagement section 34. The opening 61 extends downwards from the second lower engagement surface 44 (in the direction of magnetic adhesion). The opening 61 opens into the lower surface of the second base section 32. During plastic injection molding of the second coupling part 31, the second coupling part 31 can be manufactured through this opening 61 by joining a pair of mold halves that can be separated from each other in the top-bottom direction (Z-axis direction).The recessed section 62 on the back surface is provided for the purpose of achieving a weight reduction by lowering the plastic volume and preventing deformations (sink marks) due to volume shrinkage during cooling of the plastic. Design of the first coupling part (plug) 11 and the second coupling part (socket) 31 in the coupled state With reference to Figs. 2, 5, 6, 7 and 16, the design of the first coupling part (plug) 11 and the second coupling part (socket) 31 in the coupled state is described. Fig. 16 is a sectional view of CA-CA from Fig. 6. As clearly shown in the sectional views of Figs. 7 and 16, the first engagement section 14, in the coupled state of the coupling device 10, engages with the second engagement section 34 in the top-bottom direction. More precisely, the first engagement surface 24 of the first engagement section 14 is in surface contact with the second lower engagement surface 44 of the second engagement section 34, thus bringing the first engagement section 14 into engagement with the second engagement section 34. The first engagement section 14 is received in the concave space bounded by the second engagement receiving section 33. The second engagement section 34 is received in the concave space bounded by the first engagement receiving section 13.Simultaneously with the mechanical engagement, due to the magnetic attraction between the first magnet body (first magnet) 21 and the second magnet body (second magnet) 41, the first magnetic force attachment surface 16 and the second magnetic force attachment surface 36 are in surface contact with each other. In this coupling state, the first coupling part 11 is coupled to the second coupling part 31 in the up-down direction. The first coupling part 11 therefore cannot move in the up-down direction. At the same time, the first coupling part 11 is also coupled to the second coupling part in the "coupling direction" (positive direction of the X-axis). The first coupling part 11 therefore cannot move in the coupling direction either. Furthermore, the first coupling part 11 cannot slide in the left-right direction (Y-axis direction). However, the mechanically engaged engagement sections are formed in a circular arc shape.Therefore, the first coupling part 11 and the second coupling part 31 can rotate relative to each other along the circular arc shape of the engagement sections. In the present embodiment, the first coupling part 11 and the second coupling part 31 can thus rotate 360 ​​degrees relative to each other. As shown in Fig. 6, in the coupled state of the coupling device 10, a first gap d1 is formed between the lowest surface of the first foot section 12 of the first coupling part 11 and the uppermost surface of the second engagement section 34 of the second coupling part 31. More precisely, the first gap d1 is formed between the lowest surface of the step section 27 of the first foot section 12 and the highest surface of the second upper engagement surface 45 of the second engagement section 34. The length of the first gap d1 is greater than 5% of the total thickness D in the top-bottom direction of the coupling device 10 in the coupled state. In the coupled state of the coupling device 10, a second gap d2 is formed between the lowest surface of the flat plate section 28 of the first foot section 12 of the first coupling part 11 and the uppermost surface of the second engagement section 34 of the second coupling part 31. More precisely, the second gap d2 is formed between the lowest surface of the flat plate section 28 of the first foot section 12 and the highest surface of the second upper engagement surface 45 of the second engagement section 34. The length of the second gap d2 is greater than 10% of the total thickness D in the top-bottom direction of the coupling device 10 in the coupled state. The first gap d1 and the second gap d2 are provided so that the two elements can be easily separated from each other during the release operation of the first coupling part 11 and the second coupling part 31. Details of this function are described below. Release operation of the first coupling part (plug) 11 and the second coupling part (socket) 31 The operation for disengaging the first coupling part 11 and the second coupling part 31 is described in detail with reference to Figures 16, 17 to 18. To disengage the coupling in the coupling state of the coupling device 10 shown in Figure 16, the first coupling part 11 is moved in a sliding motion relative to the second coupling part 31 in the "release direction" (negative direction of the X-axis). During this sliding operation, the magnetic force between the first magnet body 21 and the second magnet body 41 acts strongly in the "direction of magnetic attraction". Therefore, the first coupling part 11 is typically moved in a sliding motion while maintaining surface contact between the first magnetic force attachment surface 16 and the second magnetic force attachment surface 36. Fig. 17 shows the first coupling part 11, which has been moved from the position shown in Fig. 16 in the release direction. To release the coupling, it is sufficient to move the first coupling part 11 a short distance relative to the second coupling part 31, so that the first engagement section 14 and the second engagement section 34 no longer overlap in the top-bottom direction. In actual operation, the degree of engagement between the first engagement section 14 and the second engagement section 34 is concealed by the fabric of a bag or garment and is therefore not visible. Therefore, the release operation is performed using tactile sensation. Even in this case, operation of the coupling device 10 of the present embodiment is simple due to the projecting section 51 provided on the second coupling part (socket) 31.The first engagement section 14 of the first coupling part 11 engages the projecting section 51 of the second coupling part 31 as soon as the first coupling part 11 has been moved into the position shown in Fig. 17. More precisely, the arc-shaped first inclined engagement surface 23 of the first coupling part 11 engages the arc-shaped inclined projecting surface 52 of the second coupling part 31. The sensation created when the first engagement section 14 meets the projecting section 51 is transmitted to the operator. This allows the operator to recognize that the first engagement section 14 and the second engagement section 34 do not overlap in the top-bottom direction. Furthermore, the first coupling part 11 is not moved too far relative to the second coupling part 31. This user experience can be adjusted by changing the height or shape of the protruding section.Therefore, it is easily possible to adapt the user interface to the respective purpose. When the first coupling part 11 is moved further from the impact state shown in Fig. 17 relative to the second coupling part 31, the first coupling part 11 rests on the projecting section 51, as shown in Fig. 18. The first engagement section 14 of the first coupling part 11 is thus gradually pressed upwards along the inclined projecting surface 52 of the second coupling part 31. Finally, the first magnetic contact surface 16 of the first coupling part 11 rests on the upper projecting surface 53 of the second coupling part 31. In this state, the surface contact between the first magnetic contact surface 16 and the second magnetic contact surface 36 is also broken. Furthermore, the magnetic attraction is weakened in this state. In addition, the mechanical engagement is terminated. Therefore, the operator can easily detach the first coupling part 11 from the second coupling part 31 in the desired direction. Another feature of the present embodiment that should be explicitly mentioned is that, when the first coupling part 11 rests on the projecting section 51 as shown in Fig. 18, the design is such that the first foot section 12 of the first coupling part 11 does not abut the second engagement section 34 of the second coupling part 31. This effect occurs when the second gap d2, described with reference to Fig. 6, is set rather large. In general, the second gap d2 should preferably be made small in order to make the coupling device 10 smaller or thinner (for example, by making the stepped section 27 of the first foot section thinner or by omitting the stepped section 27). However, a small second gap d2 has the disadvantage of reduced operability. Thus, in the state shown in Fig.18 the first coupling part 11 (first foot section 12) against the second coupling part 31 (second engagement section 34), since the second gap d2 is small. Therefore, in the present embodiment, the length of the second gap d2 is set such that, during operation to release the coupling, when the first magnetic force adhesion surface 16 of the first coupling part 11 comes into contact with the projecting section 51 of the second coupling part 31 and rests on the upper projecting surface 53, the first foot section 12 of the first coupling part 11 does not come into contact with the second engagement section 34 of the second coupling part 31. A suitable length for the second gap d2 to achieve this effect is therefore a value greater than 10% of the total thickness D in the top-bottom direction of the coupling device 10 in the coupled state. A preferred length of the second gap d2 lies in a range of 10% to 20% of the total thickness D in the top-bottom direction of the coupling device 10 in the coupling state. Another feature of the present embodiment that should be explicitly mentioned is that the release operation of the coupling device 10 can be performed by a different operation than the conventional sliding operation of the release operation of the coupling device 10 described with reference to Figures 16, 17 to 18. This is made possible by setting the first gap d1, described with reference to Figure 6, to a larger size and is an additional feature. In the present embodiment, the first gap d1 is provided between the lowest surface of the first foot section 12 of the first coupling part 11 and the uppermost surface of the second engagement section 34 of the second coupling part 31.Therefore, it is possible to rotate the first coupling part 11 about an engagement section front end P of the second engagement section 34 (a corner section bounded by the second inclined engagement surface 43 and the second lower engagement surface 44) without displacing the first coupling part 11 from the engagement position shown in Fig. 16 in the X-axis direction. The engagement section front end P of the second engagement section 34 bounds a line segment contained in the curved surface. Strictly speaking, the engagement section front end P shown in Fig. 16 does not rotate about a point center of rotation. However, it is possible to rotate the first coupling part 11 about a line connecting the two end segments (in the Y-axis direction) of a line segment of the circular arc bounded by the engagement section front end P, thus releasing it.A release operation of the coupling device 10, in which the first coupling part 11 described above is immediately rotated into the engagement position shown in Fig. 16, can be difficult for design reasons due to the shape of the engagement section. However, even if the first coupling part 11 is only moved to the extent that there is still some overlap in the top-bottom direction between the first engagement section 14 and the second engagement section 34, the release operation described above, which rotates the first coupling part 11, can still be applied. In this way, a design is also possible with which the release operation of the coupling device 10 can be implemented. If the coupling device 10 is to be made smaller or thinner, it would generally be preferable to reduce the first gap d1 or to omit the first gap d1 altogether. However, by setting the first gap d1 rather large in the present embodiment, some other release operations are enabled. A guideline length for the first gap d1 is that it is greater than 5% of the total thickness D in the top-bottom direction of the coupling device 10 in the engaged state. A preferred length of the first gap d1 lies in the range of 5% to 10% of the total thickness D in the top-bottom direction of the coupling device 10 in the engaged state. Coupling operation of the first coupling part (plug) 11 and the second coupling part (socket) 31 The operation for coupling the first coupling part 11 and the second coupling part 31 is essentially the reverse of the release operation shown in Figs. 16, 17 to 18. Thus, the first coupling part 11, in the release state, is moved towards the second coupling part 31 in the "coupling direction (positive direction of the X-axis)" and the "downward direction (negative direction of the Z-axis)" as shown in Fig. 18. This causes the magnetic attraction to act on the first magnet body 21 and the second magnet body 41. Simultaneously, the first magnetic contact surface 16 and the second magnetic contact surface 36 come into contact as shown in Fig. 17. Furthermore, the first coupling part 11 moves towards the second coupling part 31 in the "coupling direction (positive direction of the X-axis upwards)". Finally, the first intervention section 14 is reached, as shown in Fig.16 shown, with the second engagement section 34 in engagement, thus completing the coupling state. However, in practice, the coupling operation is performed in a state where the first coupling part 11 and the second coupling part 31 are attached to the fabric of a bag or garment. Therefore, the operator must perform the operation by feel, in a state where the positional relationship between the first coupling part 11 and the second coupling part 31 is not visible. Thus, the first coupling part 11 cannot necessarily be brought close to the second coupling part 31 in the state shown in Fig. 18. For example, the first coupling part 11, as shown in Fig. 19, may rest on the second upper engagement surface 45 of the second engagement section 34 of the second coupling part 31. If the first coupling part 11 is pressed downwards in the state shown in Fig. 19, it will not overcome the second upper engagement surface 45 of the second coupling part 31. Therefore, the operator must attempt to move the first coupling part 11 by feel relative to the second coupling part 31 in the X-axis or Y-axis direction. Furthermore, once the first coupling part 11 has been returned in the "release direction," a "return slide operation" is required to move it in the opposite direction. This allows the first coupling part 11 to overcome the second upper engagement surface 45 of the second coupling part 31, as in the state of Fig. 18.The return stroke of this "return slide control" should be as small as possible. In the present embodiment, a measure is applied that reduces the return stroke. Specifically, in the coupling device 10 of the present embodiment, the second engagement section 34 of the second coupling part 31 has the second inclined engagement surface 43. Compared to a coupling device that does not have the second inclined engagement surface 43 (as in the case of patent document 2), the return travel during the "return slide operation" is therefore small. Furthermore, in the coupling device 10 of the present embodiment, compared to a coupling device that does not have the first inclined engagement surface 23 (as in the case of patent document 2), the return dimension during the “return slide operation” is even smaller. Furthermore, in the coupling device 10 of the present embodiment, the projecting section end surface 57A and the curved projecting section displacement surface 57B are provided at the two end sections of the second engagement section 34 of the second coupling part 31. Compared to a coupling device that does not have these projecting section surfaces (as in the case of patent document 2), the "return sliding operation" is therefore smoother. With reference to Fig. 19, the details of the "reset slide control" of the coupling device 10 of the present embodiment are described. First, the first coupling part 11 is moved from the position shown in Fig. 19 so that it returns in the "release direction." The second engagement section 34 of the second coupling part 31 now has the second inclined engagement surface 43 as the slope lowered in the "release direction." Compared to a coupling device that does not have the second inclined engagement surface 43, the first coupling part 11 can begin its downward movement correspondingly earlier. Preferably, the first inclined engagement surface 23 is also provided as a slope descending in the "release direction" on the first engagement section 14 of the first coupling part 11.In comparison to a coupling device that does not have this sloping ramp, the first coupling part 11 can begin its downward movement earlier due to the sloping ramp. Fig. 20 shows the first engagement section 14 of the first coupling part 11, which, due to the return slide mechanism, has moved downward and in the release direction along the second inclined engagement surface 43 of the second coupling part 31. In the state shown in Fig. 20, the lowest part of the first coupling part 11 is in contact with the second coupling part 31. More precisely, a portion in the region of the edge section of the first magnetic force adhesion surface 16 of the first coupling part 11 is in contact with the second magnetic force adhesion surface 36. The relationship between the radius of curvature of the circular arc part of the first engagement section 14 and the radius of curvature of the circular arc part of the second engagement section 34 changes the value shown in Fig.The contact state shown in Fig. 20. In the embodiment discussed above, the radius of curvature of the circular arc portion of the first engagement section 14 and the radius of curvature of the circular arc portion of the second engagement section 34 are approximately the same size. The contact state shown in Fig. 20 also changes due to the relationship between the width in the left-right direction of the circular arc portion of the first engagement section 14 and the width in the left-right direction of the circular arc portion of the second engagement section 34. In the embodiment discussed above, the width in the left-right direction of the circular arc portion of the first engagement section 14 and the width in the left-right direction of the circular arc portion of the second engagement section 34 are approximately the same size. From the state shown in Fig. 20, the first coupling part 11 moves further in the "release direction." This results in the state shown in Fig. 18. Therefore, the first coupling part 11 then moves, as shown in Fig. 17, sliding in the engagement direction. This ultimately results in the coupling state shown in Fig. 16. In the coupling state shown in Fig. 20, the first coupling part 11 can easily move downwards along the second inclined engagement surface 43. Therefore, the operator can push the first coupling part 11 downwards without necessarily having to move it in the release direction. The state shown in Fig. 18 can also be achieved in this way. The feel of this operation is similar to that of a snap button. In the present embodiment, the coupling part can be coupled with an operation similar to that of a snap button. Furthermore, the projecting section end surface 57A and the curved projecting section displacement surface 57B are provided at the two end sections of the second engagement section 34 of the second coupling part 31. During the return slide operation, the first engagement section 14 of the first coupling part 11 can therefore also be moved along the projecting section end surface 57A and the curved projecting section displacement surface 57B. Thus, even if, for example, due to a slight deviation between the position of the first coupling part 11 in the left-right direction and the position of the second coupling part 31 in the left-right direction, good surface contact between the first inclined engagement surface 23 and the second inclined engagement surface 43 is not achieved, the first engagement section 14 can easily be guided "downwards" along the projecting section end surface 57A and the curved projecting section displacement surface 57B.Therefore, a sensation that arises when the second coupling part 31 gets stuck on the two end sections of the second engagement section 34 is prevented. In the present embodiment, the return slide operation can be performed in this state. As described above, the coupling device 10 of the present embodiment exhibits excellent ease of use in both engagement and disengagement. Second embodiment: Improvement of the introduction characteristics Fig. 21 is an illustrative view of the coupling device 10 according to a further embodiment (second embodiment). In the coupling device 10 of the second embodiment, the thickness of the plastic at the end section of the second engagement section 34 of the second coupling part (socket) 31 is slightly reduced. This facilitates engagement during coupling operation. More precisely, a portion of the curved projection section displacement surface 57B, which is arranged at the end section in the left-right direction of the second engagement section 34, is reduced in thickness. The second embodiment is described in more detail with reference to the symbols R1, L2, and C shown in Fig. 21. Fig. 21 shows the second coupling part 31 viewed "downward" (direction of magnetic adhesion or "negative direction of the Z-axis"). A radius of curvature of a left-right centered position of the second engagement section 34 of the second coupling part 31 is defined as a first radius R1. A distance from the center point C of the first radius R1 to a defined edge section of the curved projection section displacement surface 57B is defined as a second length L2. Here, the "defined edge section of the curved projection section displacement surface 57B" denotes any part of the edge section of the inner circumferential surface of the curved projection section displacement surface 57B having an engagement function. In this case, the second length L2 is set greater than the first radius R1.By using such a shape, in which part of the edge section of the curved projection section displacement surface 57B is omitted, less injection molding plastic is consumed than in the edge section of the second engagement section 34. Thus, the second engagement section 34 is designed such that the second length L2 is greater than the first radius R1. According to this design, when the coupling parts are coupled, the first engagement section 14 of the first coupling part 11 does not readily collide with the edge section of the curved projection section displacement surface 57B. Therefore, the first engagement section 14 of the first coupling part 11 can be more easily guided into the position of alignment with the second engagement section 34. Furthermore, in the second embodiment, a projection section curvature radius change surface 71 is preferably provided between the curved projection section displacement surface 57B of the second coupling part 31 and the second inclined engagement surface 43. When the second coupling part 31 is viewed "downward" (direction of magnetic adhesion or "negative direction of the Z-axis"), a distance from the center point C of the first radius R1 to a defined edge segment of the projection section curvature radius change surface 71 is defined as the third length L3. The third length L3 is set to be greater than the first radius R1. By using this shape, in which a portion of the edge section is omitted extending beyond the projection section curvature radius change surface 71, which has an even larger area than the curved projection section displacement surface 57B, less injection-molded plastic is consumed than in the edge section of the second engagement section 34. Thus, the second engagement section 34 is designed such that the third length L3 is greater than the first radius R1 over a wider area. Therefore, when the coupling parts are connected over a large area from the curved projection section displacement surface 57B to the projection section curvature radius change surface 71, the first engagement section 14 of the first coupling part 11 does not readily abut the edge sections of the curved surface and the change surface.Therefore, the first engagement section 14 of the first coupling part 11 can more easily be guided into the position of alignment with the second engagement section 34. The coupling device 10 of the second embodiment described above can achieve this effect even more clearly with the "reset slide operation," which was also described in the first embodiment. Thus, less injection-molded plastic is consumed at the edge section of the projecting section end surface 57A and at the edge section of the curved projecting section displacement surface 57B than at the edge section of the second engagement section 34. Therefore, the first engagement section 14 of the first coupling part 11 can be easily moved "downwards" ("negative direction of the Z-axis direction") during the "reset slide operation." Third embodiment Figures 22, 23 to 24 are illustrative views of the coupling device 10 according to a further embodiment (third embodiment). Figure 22 is a top view of the coupling device 10 of the third embodiment. Figure 23 is a left side view of it. Figure 24 is a perspective view of it. In the coupling device 10 of the third embodiment, an interruption section 75 is provided between the second engagement section 34 of the second coupling part (socket) 31 and the projecting section 51. This interruption section is formed by reducing the thickness of the plastic "in the upward direction" ("direction of separation of the magnetic force"). As can be seen from the side view of Figure 22, Figure 23 is a view of the coupling device 10 of the third embodiment.As can be clearly seen in Figure 23, the upper surface of the interruption section 75 is arranged at a lower position than the second upper engagement surface 45 of the second engagement section 34 and at a lower position than the upper projection surface 53 of the projection section 51. By providing the interruption section 75 in this way, the mold used in manufacturing the second coupling part 31 can be simplified. A weight reduction of the second coupling part 31 can also be achieved. Furthermore, the design variability of the second coupling part 31 is increased. Fourth embodiment Fig. 25 is an illustrative view of the coupling device 10 according to a further embodiment (fourth embodiment). In the coupling device 10 of the fourth embodiment, the second upper engagement surface 45 on the upper surface of the second engagement section 34 of the second coupling part 31 has an inclined surface that slopes downwards towards the "release direction" (negative direction of the "X-axis direction") of the coupling device 10. This sloping inclined surface of the second upper engagement surface 45 can be a flat surface or a curved surface. In this way, the second upper engagement surface 45 has a sloping surface that drops away towards the "release direction" (negative direction of the "X-axis direction"). This ensures that, when the coupling parts are coupled, the first engagement section 14 and the first magnetic force adhesion surface 16 of the first coupling part 11 are smoothly guided along the sloping surface of the second upper engagement surface 45 towards the projection section 51. This improves ease of use during coupling. According to the coupling device 10 discussed above, the coupled coupling parts can be rotated relative to each other. Furthermore, a coupling device can be achieved that features a magnetic force-utilizing coupling mechanism with excellent ease of use for both engagement and disengagement. The second coupling part 31 also has a shape that allows it to be formed by injection molding using mold halves that can be separated from each other in the top-bottom direction. Therefore, the mass production capability of the coupling device according to the present embodiment is also excellent. The present embodiment is not limited by the embodiments discussed above. Technical elements that are essentially the same as the technical elements described in the embodiments discussed above, or technical elements that are obvious to a person skilled in the art to achieve the same effects as those technical elements, may be applied to the embodiments discussed above as substitute or supplementary techniques in a suitable manner. The elements illustrated in the figures and identified by reference numbers in the descriptions of the embodiments discussed above are specified as the minimum required design elements in the present embodiment. Such a specification does not mean that the coupling device of the present embodiment is formed exclusively from the design elements described and identified by reference numbers in the figures. QUOTES INCLUDED IN THE DESCRIPTION This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature US 4700436

[0003] US 2011 / 0265289

[0004]

Claims

Coupling device comprising a first coupling part with a first magnetic body and a first engagement section and a second coupling part with a second magnetic body and a second engagement section, wherein at least one of the first magnetic body and the second magnetic body comprises a permanent magnet, wherein the first engagement section and the second engagement section are configured such that they engage with each other, wherein the first coupling part and the second coupling part are configured such that, by means of a magnetic force in the direction of the magnetic adhesion generated between the first magnetic body and the second magnetic body when the first engagement section and the second engagement section are engaged with each other, a first magnetic adhesion surface of the first coupling part is in surface contact with a second magnetic adhesion surface of the second coupling part.wherein at least one section of the first engagement section of the first coupling part has a circular arc shape, wherein at least one section of the second engagement section of the second coupling part has a circular arc shape, wherein the first coupling part is rotatable with respect to the second coupling part when the first engagement section and the second engagement section are engaged with each other, and wherein the second engagement section of the second coupling part has a second inclined engagement surface which is inclined with respect to the direction of magnetic adhesion. Coupling device according to claim 1, wherein a projection section is provided on the second coupling part on the side opposite the second engagement section, wherein a circular arc center of at least one section of the circular arc-shaped second engagement section lies between them, and at least one section of the projection section has a circular arc shape. Coupling device according to claim 2, wherein the first coupling part includes a first foot section in the form of a flat plate, wherein, when, during operation to release the first coupling part from the second coupling part, a first magnetic force adhesion surface of the first coupling part rests on the projection section of the second coupling part, the first foot section is not in contact with the second engagement section of the second coupling part. Coupling device according to claim 2 or 3, wherein a linear guide section is provided on the second coupling part between the second engagement section and the projection section. Coupling device according to claim 1 or 2, wherein at least one section of the first engagement section having a circular arc shape has a first inclined engagement surface, wherein the first inclined engagement surface is inclined with respect to the direction of magnetic adhesion. Coupling device according to claim 1 or 2, wherein the second coupling part has a second upper engagement surface on the upper surface of the second engagement section, the first coupling part includes a first foot section in the form of a flat plate, the first foot section is provided such that it extends further upwards in relation to the first engagement section, and a first gap between the first foot section of the first coupling part and the second engagement section, when the first coupling part and the second coupling part are engaged with each other, is greater than 5% of a total thickness in the top-bottom direction of the coupling device. Coupling device according to claim 1 or 2, wherein an opening hole is provided on the second engagement section, which extends in the direction of the magnetic attachment. Coupling device according to claim 1 or 2, wherein the second coupling part has a second upper engagement surface on the upper surface of the second engagement section, a projecting section end surface is provided on the two end sections of the second engagement section, the projecting section end surface has an inclined surface that slopes down from the second upper engagement surface, and a curved projecting section displacement surface is provided between the projecting section end surface and the second inclined engagement surface. Coupling device according to claim 8, wherein, on the second coupling part, when viewed in the direction of magnetic adhesion, a distance from a center point of a radius of curvature at a left-right central position of the second engagement section to a defined edge section of the curved projection section displacement surface is greater than the radius of curvature. Coupling device according to claim 9, wherein a protrusion section radius of curvature change surface is provided between the curved protrusion section displacement surface and the second inclined engagement surface, and on the second coupling part, when viewed in the direction of magnetic adhesion, a distance from the center point to a defined edge section of the protrusion section radius of curvature change surface is greater than the radius of curvature. Coupling device according to claim 2 or 3, wherein an interruption section is provided between the second engagement section and the projection section and the projection section is thickness-reduced at the interruption section in the direction of magnetic adhesion. Coupling device according to claim 1 or 2, wherein the second coupling part has a second upper engagement surface on the upper surface of the second engagement section, wherein the second upper engagement surface has an inclined surface which lowers in the release direction of the coupling device.

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