Permanent electromagnetic holder

Abstract

To provide a permanent electromagnetic holder that can determine the adhesion state of an object with a simple configuration.SOLUTION: A permanent electromagnetic holder 10 includes a magnetic force generating unit 12, a yoke unit 14, and a lead switch 16. The magnetic force generating unit 12 includes a coil 20, a first magnet 22 that is magnetized in a first direction X1 or a second direction X2 depending on the direction of current flow to the coil 20, and a second magnet 24 whose magnetization direction is fixed. The yoke unit 14 has an attraction surface 14a that attracts an object to be attracted 100. The lead switch 16 is provided on the yoke unit 14 and operates on the basis of the magnetic flux generated by the magnetic force generating unit 12. The attraction surface 14a is switched between a state in which the object to be attracted 100 is attracted and a state in which the object to be attracted 100 is not attracted depending on the magnetization direction of the first magnet 22. The lead switch 16 is in a closed state when the object to be attracted 100 is attracted to the attraction surface 14a, and is in an open state when the object to be attracted 100 is not attracted to the attraction surface 14a.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a permanent electromagnetic holder that can be switched between a state in which an object is attracted by the magnetic force of a permanent magnet and a state in which the object is not attracted. [Background technology]

[0002] 2. Description of the Related Art Conventionally, various types of attraction devices have been proposed that attract an object by using the magnetic force of a permanent magnet. Some of these attraction devices are provided with a mechanism for determining the attraction state of the object.

[0003] For example, Patent Document 1 discloses an attraction device including a permanent magnet, a yoke, and an attraction state determination device. The attraction state determination device includes a sensor that detects magnetic flux density at a predetermined position of the yoke, and a determination unit that determines whether the attraction state is good or bad based on the magnetic flux density detected by the sensor using a predefined relational expression. The sensor is composed of a hall sensor, a search coil, etc.

[0004] Patent Document 1 describes that with the above configuration, a sensor provided in the yoke detects the magnetic flux density leaking from the yoke, and the quality of the adsorption state is determined based on the detected magnetic flux density, thereby making it possible to appropriately determine whether the adsorption state is good or bad. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2022-89281 Summary of the Invention [Problem to be solved by the invention]

[0006] Incidentally, when determining the attraction state of the target object using a sensor constituted by a Hall sensor, a search coil, etc., as described above, it is necessary to properly measure the output voltage of the sensor and to properly determine the attraction state based on the measured output voltage, which makes the device configuration complicated.

[0007] SUMMARY OF THE PRESENT EMBODIMENTS The present invention has an object to provide a permanent electromagnetic holder capable of determining the attraction state of an object to be attracted with a simple configuration. [Means for solving the problem]

[0008] According to one aspect of the present invention, there is provided a permanent electromagnetic holder comprising: A magnetic force generating unit including a coil, a first magnet that is magnetized in a first direction along the axial direction of the coil or a second direction opposite to the first direction depending on a direction of current flow through the coil, and a second magnet whose magnetization direction is fixed; a yoke portion that houses the magnetic force generating portion and has an attraction surface that attracts an object to be attracted; a reed switch provided in the yoke portion and operated based on the magnetic flux generated by the magnetic force generating portion, the attraction surface is switched between a state in which it is attracted to the attraction target and a state in which it is not attracted to the attraction target depending on the magnetization direction of the first magnet, The reed switch is characterized in that it is in a closed state when the object to be attracted is attracted to the attraction surface, and is in an open state when the object to be attracted is not attracted to the attraction surface. Effect of the Invention

[0009] According to the present invention, a permanent electromagnetic holder capable of determining the attraction state of an object to be attracted with a simple configuration is obtained. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a front view showing a permanent electromagnetic holder according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a plan view showing the permanent electromagnetic holder. [Diagram 3] FIG. 3 is a schematic cross-sectional view showing a portion AA in FIG. [Figure 4] FIG. 4 is a diagram showing the permanent electromagnetic holder when the attraction surface is in a state where it is attracted to an object to be attracted. [Diagram 5] FIG. 5 is a diagram showing the permanent electromagnetic holder in a state where the attraction surface attracts the attraction target, but the attraction target is slightly separated from the attraction surface. [Figure 6] FIG. 6 is a diagram showing the permanent electromagnetic holder when the attraction surface is not attracted to the object to be attracted. [Figure 7] FIG. 7 is a diagram for explaining the flow of magnetic flux to the reed switch. [Figure 8] FIG. 8 is a diagram showing a modified example of the permanent electromagnetic holder. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a permanent electromagnetic holder according to an embodiment of the present invention will be described with reference to the drawings.

[0012] (Permanent electromagnetic holder configuration) FIG. 1 is a front view showing a permanent electromagnetic holder according to an embodiment of the present invention, and FIG. 2 is a plan view showing the permanent electromagnetic holder. FIG. 3 is a schematic cross-sectional view showing the AA portion of FIG. 2. Although details will be described later, the permanent electromagnetic holder 10 according to this embodiment is configured to be switchable between a state in which an object to be attracted 100 made of a magnetic material is attracted and a state in which the object to be attracted 100 is not attracted. The permanent electromagnetic holder 10 is used, for example, in industrial robots, unmanned transport devices, drones, etc. to attract and hold iron products, but the use of the permanent electromagnetic holder 10 is not limited to these uses, and can be used for various uses to attract objects to be attracted made of a magnetic material.

[0013] As shown in FIGS. 1 to 3, a permanent electromagnetic holder 10 according to this embodiment includes a magnetic force generating unit 12, a yoke unit 14 that houses the magnetic force generating unit 12, and a reed switch 16 provided on the yoke unit 14.

[0014] As shown in Fig. 3, the magnetic force generating unit 12 has a coil 20, a first magnet 22, and a second magnet 24. Note that in Fig. 1 and Fig. 3, the direction parallel to the axial direction of the coil 20 is indicated by an arrow X. Hereinafter, the direction parallel to the axial direction of the coil 20 will be simply referred to as the axial direction X.

[0015] The coil 20 is electrically connected to an external power supply (not shown). The coil 20 is a solenoid coil. A first magnet 22 is provided inside the coil 20. The coil 20 magnetizes the first magnet 22 when current is applied thereto.

[0016] In this embodiment, the first magnet 22 has a cylindrical shape and is provided coaxially with the coil 20. The first magnet 22 is magnetized in a first direction X1 along the axial direction X or in a second direction X2 opposite to the first direction X1, depending on the direction of current flow to the coil 20. That is, the magnetization direction of the first magnet 22 switches depending on the direction of current flow to the coil 20 when the first magnet 22 is magnetized by the coil 20. In this specification, the magnetization direction of the magnet means the direction from the S pole to the N pole. In the state shown in FIG. 3, the first magnet 22 is magnetized in the first direction X1.

[0017] As the first magnet 22, for example, an alnico magnet, an iron-chromium-cobalt magnet, or the like can be used. In this embodiment, the first magnet 22 has a shape in which the length in the axial direction X is smaller than the diameter (the length in the direction perpendicular to the axial direction X), but the length in the axial direction X may be larger than the diameter. In this embodiment, the length of the first magnet 22 in the axial direction X is smaller than the length of the coil 20, but the length of the first magnet 22 in the axial direction X may be larger than the length of the coil 20.

[0018] The second magnet 24 has a cylindrical shape and is provided coaxially with the coil 20 and the first magnet 22. In this embodiment, the second magnet 24 is provided outside the coil 20. The magnetization direction of the second magnet 24 is fixed. In this embodiment, the second magnet 24 is magnetized in a direction along the axial direction X. More specifically, the second magnet 24 is magnetized in a first direction X1. The coercive force of the second magnet 24 is greater than that of the first magnet 22. As the second magnet 24, for example, a neodymium magnet is used.

[0019] The magnetic force generating unit 12 is housed in a yoke portion 14. The yoke portion 14 is made of a magnetic material such as iron. In this embodiment, the yoke portion 14 has a substantially rectangular parallelepiped shape. The yoke portion 14 is provided with an attraction surface 14a that attracts the attraction target 100. The attraction surface 14a is provided on one side of the first magnet 22 and the second magnet 24 in the axial direction X.

[0020] In this embodiment, the yoke portion 14 has a first yoke component 40, a second yoke component 42, and a third yoke component 44. In this embodiment, the first yoke component 40 has a substantially cylindrical shape. The first yoke component 40 is provided on one side of the coil 20, the first magnet 22, and the second magnet 24 in the axial direction X. In this embodiment, the first yoke component 40 and the second magnet 24 have substantially the same outer diameter, and the outer circumferential surface of the first yoke component 40 and the outer circumferential surface of the second magnet 24 are substantially flush with each other.

[0021] A recess 41a is formed in the center of one end face 41 of the first yoke component 40 in the axial direction X. In this embodiment, an annular region 41b on the outer side of the recess 41a in the end face 41 functions as a first region of the adsorption surface 14a. Hereinafter, the region 41b of the end face 41 will be referred to as the first region 41b.

[0022] The second yoke component 42 is formed in a rectangular tube shape and is provided so as to surround the first yoke component 40 from the outside. In this embodiment, the second yoke component 42 has an outer circumferential surface with a rectangular cross section and an inner circumferential surface with a circular cross section. In this embodiment, an end face 43 on one side of the second yoke component 42 in the axial direction X functions as the second region of the adsorption surface 14a. Hereinafter, the end face 43 will be referred to as the second region 43.

[0023] The adsorption surface 14a (the first region 41b and the second region 43) is formed in a planar shape so as to extend in a direction intersecting the axial direction X. In this embodiment, the adsorption surface 14a is provided so as to extend in a direction substantially perpendicular to the axial direction X.

[0024] The second yoke member 42 has a cavity 45 that opens toward the other side in the axial direction X. The cavity 45 has a bottom surface 45a, a cylindrical wall surface 45b extending from the outer edge of the bottom surface 45a toward the other side in the axial direction X, an annular flange surface 45c extending from the wall surface 45b in a direction intersecting the axial direction X, and a cylindrical wall surface 45d extending from the outer edge of the flange surface 45c toward the other side in the axial direction X.

[0025] A gap is formed between the first yoke member 40 and the second yoke member 42 in the radial direction of the coil 20. A cylindrical spacer 50 made of a non-magnetic material such as resin is inserted into this gap. The spacer 50 is provided so as to surround the second magnet 24 and the first yoke member 40 and extend to the attraction surface 14a. In the radial direction of the coil 20, the first region 41b of the attraction surface 14a is located inside the spacer 50, and the second region 43 of the attraction surface 14a is located outside the spacer 50. In this embodiment, the spacer 50 functions as a non-magnetic part. It is not necessary to insert the spacer 50 between the first yoke member 40 and the second yoke member 42. In this case, the air in the gap functions as a non-magnetic part.

[0026] The third yoke component 44 is provided on the other side of the coil 20, the first magnet 22, and the second magnet 24 in the axial direction X. The third yoke component 44 has an outer circumferential surface of substantially the same shape as the outer circumferential surface of the second yoke component 42. In this embodiment, the second yoke component 42 and the third yoke component 44 are connected so that the outer circumferential surfaces of the second yoke component 42 and the third yoke component 44 are substantially flush with each other. An annular spacer 52 is provided between the third yoke component 44 and the second magnet 24. The spacer 52 is made of, for example, a magnetic material.

[0027] A cavity 47 that opens toward one side in the axial direction X is formed in the third yoke component 44. The cavity 47 is provided to face the cavity 45 in the axial direction X. The cavity 47 has a bottom surface 47a and a cylindrical wall surface 47b that extends from the outer edge of the bottom surface 47a toward one side in the axial direction X. In this embodiment, of an end surface 49 on one side of the third yoke component 44 in the axial direction X, an annular region 49a surrounding the cavity 47 is exposed in the cavity 45. Hereinafter, the region 49a of the end surface 49 exposed in the cavity 45 will be referred to as an exposed surface 49a.

[0028] The reed switch 16 is provided outside the spacer 50 in the radial direction of the coil 20. At least a portion of the reed switch 16 is located on one side (the attracting surface 14a side) of the first magnet 22 and the second magnet 24 in the axial direction X. In this embodiment, the reed switch 16 is provided in a space formed by the cavities 45, 47. More specifically, the reed switch 16 is held in the cavities 45, 47 by filling the cavities 45, 47 with an elastic adhesive (not shown). In this embodiment, the reed switch 16 is held in the cavities 45, 47 such that the length direction of the reed switch 16 is along the axial direction X.

[0029] The reed switch 16 has a pair of reeds 16a and a glass tube 16b that accommodates the tips (contacts) of the reeds 16a. The pair of reeds 16a are electrically connected to an external detector via a pair of lead wires 18 (see FIG. 2), and the detector detects whether the contacts of the reed switch 16 are open or closed. Although a detailed description is omitted, in this embodiment, the pair of reeds 16a and the pair of lead wires 18 are connected in the cavities 45 and 47. The pair of lead wires 18 pass through a guide hole (not shown) formed in the yoke portion 14 (the third yoke member 44 in this embodiment) and are drawn out of the yoke portion 14 from the cavities 45 and 47. As the reed switch 16, various known reed switches in which the contacts are opened and closed by the magnetic flux generated by a magnet can be used, and therefore a detailed description of the reed switch 16 is omitted.

[0030] In this embodiment, the reed switch 16 is held in the hollows 45 and 47 so that the portions of the pair of reed pieces 16a exposed from the glass tube 16b face the wall surfaces 45b and 47b, and the contact portions of the pair of reed pieces 16a (the center portions of the reed switch 16) face the wall surface 45d. In this embodiment, the wall surfaces 45b and 47b function as a pair of guide surfaces facing both ends of the reed switch 16 in the radial direction of the coil 20. In addition, the flange surface 45c, the wall surface 45d, and the exposed surface 49a of the end surface 49 function as a concave surface that is concave in a direction away from the reed switch in the radial direction from the pair of guide surfaces. The functions of the pair of guide surfaces (wall surfaces 45b and 47b) and the concave surface (flange surface 45c, wall surface 45d, and exposed surface 49a) will be described later.

[0031] (Permanent electromagnetic holder operation) In the permanent electromagnetic holder 10 according to this embodiment, the magnetization direction of the first magnet 22 is switched by changing the current flow direction of the coil 20, thereby switching the state of the attraction surface 14a between a state in which it is attracted to the attraction target 100 and a state in which it is not attracted to the attraction target 100. The time for which current is passed through the coil 20 when switching the state of the attraction surface 14a as described above is, for example, about 0.01 to 0.2 seconds. Note that the method of switching the magnetization direction of the first magnet 22 is the same as that of the conventional permanent electromagnetic holder 10, and therefore a detailed description thereof will be omitted.

[0032] FIG. 4 is a diagram showing the permanent electromagnetic holder 10 when the attraction surface 14a is in a state where it is attracted to the attraction target 100. In FIG. 4 and FIGS. 5 and 6 described later, the flow of magnetic flux is simplified and shown by thick lines. In the example shown in FIG. 4, the magnetization direction of the first magnet 22 is set to the first direction X1, similar to that of the second magnet 24. In this case, the magnetic flux generated by the first magnet 22 and the second magnet 24 flows from the first yoke member 40 to the attraction target 100 through the first region 41b of the attraction surface 14a, and then flows from the attraction target 100 to the second yoke member 42 through the second region 43 of the attraction surface 14a. As a result, the attraction target 100 is attracted to the attraction surface 14a. At this time, magnetic flux also flows through the reed switch 16, and the reed switch 16 is in a closed state.

[0033] 5, even when the object 100 to be attracted is separated from the attraction surface 14a, if the distance between the attraction surface 14a and the object 100 to be attracted is small, part of the magnetic flux generated by the first magnet 22 and the second magnet 24 flows through the object 100 to be attracted. However, the magnetic flux density of the magnetic flux flowing through the reed switch 16 is lower than when the object 100 to be attracted is attracted to the attraction surface 14a. In this embodiment, the sensitivity and position of the reed switch 16 are determined so that the reed switch 16 is in the closed state only when the object 100 to be attracted is attracted to the attraction surface 14a, and the reed switch 16 is in the open state when the object 100 to be attracted is separated even slightly from the attraction surface 14a.

[0034] FIG. 6 is a diagram showing the permanent electromagnetic holder 10 when the attraction surface 14a is not attracted to the attraction target 100. In the example shown in FIG. 6, the magnetization direction (second direction X2) of the first magnet 22 and the magnetization direction (first direction X1) of the second magnet 24 are opposite to each other. In this case, even if the attraction target 100 comes into contact with the attraction surface 14a, the magnetic flux generated by the first magnet 22 and the second magnet 24 does not flow, or hardly flows, through the attraction target 100 and the second yoke member 42. For this reason, the attraction target 100 is not attracted to the attraction surface 14a. Since no magnetic flux flows, or hardly flows, through the reed switch 16, the reed switch 16 is in an open state.

[0035] (Effects of this embodiment) As described above, in the permanent electromagnetic holder 10 according to this embodiment, it is possible to determine whether the attraction target 100 is attracted to the attraction surface 14a by detecting whether the reed switch 16 is in an open state or a closed state. In this case, it is possible to determine whether the attraction target 100 is attracted with a simpler configuration than in the case of detecting the magnetic flux density.

[0036] In this embodiment, the first magnet 22 is provided inside the coil 20 and the second magnet 24 in the radial direction of the coil 20, and the reed switch 16 is provided outside the coil 20 and the second magnet 24 in the radial direction of the coil 20. In this case, the reed switch 16, the coil 20 (or the second magnet 24), and the first magnet 22 can be arranged so as to overlap each other when viewed from the radial direction of the coil 20, so that the dimension of the permanent electromagnetic holder 10 in the axial direction X can be reduced. Note that in this embodiment, the reed switch 16, the coil 20, the first magnet 22, and the second magnet 24 are arranged so as to overlap each other when viewed from the radial direction of the coil 20. This allows the dimension of the permanent electromagnetic holder 10 in the axial direction X to be sufficiently reduced.

[0037] In this embodiment, the reed switch 16 is held in the cavities 45, 47 so that its length direction is along the axial direction X. In this embodiment, the magnetic flux generated by the first magnet 22 and the second magnet 24 flows mainly in the axial direction X through the second yoke member 42 outside the spacer 50. Therefore, by making the length direction of the reed switch 16 along the axial direction X, it is possible to ensure a sufficient magnetic flux density of the magnetic flux flowing through the reed switch 16. This allows the reed switch 16 to be easily operated.

[0038] Furthermore, as described above, the reed switch 16 can be protected by being held within the cavities 45, 47. This makes it possible to suppress deterioration of the reed switch 16. In this embodiment, the reed switch 16 is held by an elastic adhesive filled within the cavities 45, 47. This makes it possible to more reliably protect the reed switch 16.

[0039] In this embodiment, the cavities 45, 47 include a pair of guide surfaces (wall surfaces 45b, 47b) facing both ends of the reed switch 16 in the radial direction of the coil 20, and a concave surface (a surface formed by the flange surface 45c, the wall surface 45d, and the exposed surface 49a) recessed at least toward the coil 20 between the pair of guide surfaces (wall surfaces 45b, 47b). This allows a sufficient gap to be formed around the center of the reed switch 16. Here, as shown by the arrows in FIG. 7, the magnetic flux that flows from the attraction target 100 to a portion of the second yoke member 42 near the reed switch 16 is divided into a path that bypasses the cavities 45, 47 and a path that passes through the reed switch 16, and flows toward the third yoke member 44. At this time, the path through reed switch 16 is shorter than the path that bypasses cavities 45, 47, so the magnetic flux that has flowed to the portion of second yoke member 42 near reed switch 16 is more likely to flow to reed switch 16. In particular, in this embodiment, a sufficient gap can be formed around reed switch 16 as described above, so the distance of the path that bypasses cavities 45, 47 can be made sufficiently long. As a result, magnetic flux can be efficiently directed to reed switch 16, and reed switch 16 can be reliably operated.

[0040] In this embodiment, at least a portion of the reed switch 16 is located on one side in the axial direction X (the side of the attraction surface 14a) of the first magnet 22 and the second magnet 24. In this case, the magnetic flux that flows from the attraction target 100 into the second yoke member 42 via the attraction surface 14a can be efficiently passed to the reed switch 16.

[0041] (Modification) In the above embodiment, the case where the second magnet 24 is provided outside the coil 20 has been described. However, the coil 20 may be provided outside the second magnet 24.

[0042] In the above embodiment, the second magnet 24 is magnetized so that one side in the axial direction X is an N pole and the other side is an S pole, but the magnetization direction of the second magnet 24 may be opposite to that of the above embodiment. In this case as well, by matching the magnetization direction of the first magnet 22 with the magnetization direction of the second magnet 24, the attraction surface 14a is in a state in which it attracts the attraction target 100, and by making the magnetization direction of the first magnet 22 opposite to the magnetization direction of the second magnet 24, the attraction surface 14a is in a state in which it does not attract the attraction target 100.

[0043] In the above embodiment, the yoke portion 14 is configured from three yoke members 40, 42, and 44. However, the yoke portion 14 may be configured from two or four or more yoke members. For example, in the above-mentioned permanent electromagnetic holder 10, the second yoke member 42 and the third yoke member 44 may be integrally formed.

[0044] In the above embodiment, the first magnet 22 has a cylindrical shape, but the first magnet 22 may have a rectangular column shape. In the above embodiment, the second magnet 24 has a cylindrical shape, but the second magnet 24 may have a rectangular tube shape.

[0045] In the above embodiment, the permanent electromagnetic holder 10 is described as having one reed switch 16, but the permanent electromagnetic holder 10 may be provided with a plurality of reed switches 16. In this case, for example, a plurality of reed switches 16 with different sensitivity values ​​may be provided so as to be able to distinguish between the state shown in Fig. 5 (a state in which the adsorption surface 14a can adsorb the adsorption target 100, but the adsorption target 100 is separated from the adsorption surface 14a) and the state shown in Fig. 6 (a state in which the adsorption surface 14a cannot adsorb the adsorption target 100).

[0046] In the above embodiment, the permanent electromagnetic holder 10 is described as having one magnetic force generating unit 12, but as shown in Fig. 8, the permanent electromagnetic holder 10a may have a plurality of (three in Fig. 8) magnetic force generating units 12. In Fig. 8, (a) is a schematic front view showing the permanent electromagnetic holder 10a, and (b) is a schematic plan view showing the permanent electromagnetic holder 10a.

[0047] In the permanent electromagnetic holder 10a shown in FIG. 8, three magnetic force generating units 12 are accommodated in a yoke portion 140. The yoke portion 140 has three first yoke members (similar in configuration to the first yoke member 40 described above) provided on one side of each magnetic force generating unit 12 in the axial direction X, a second yoke member 42a provided so as to surround the outside of the three first yoke members, and a third yoke member 44a connected to the second yoke member 42a so as to cover the three magnetic force generating units 12 from the other side in the axial direction X. As in the permanent electromagnetic holder 10 described above, a spacer 50 (see FIG. 3) is provided between each magnetic force generating unit 12 and the second yoke member 42a. In this embodiment, an attraction surface 140a is formed by the three first yoke members and the second yoke member 42a.

[0048] In this embodiment, three magnetic force generating units 12 are arranged in a radial direction of the coil 20 (see FIG. 3). The reed switch 16 is provided between adjacent magnetic force generating units 12. In this embodiment, the second yoke member 42a and the third yoke member 44a also form a cavity similar to the cavities 45, 47 of the permanent electromagnetic holder 10 described above, and the reed switch 16 is held in the cavity. In the example shown in FIG. 8, the reed switch 16 is provided between the leftmost magnetic force generating unit 12 and the central magnetic force generating unit 12, but a further reed switch 16 may be provided between the rightmost magnetic force generating unit 12 and the central magnetic force generating unit 12.

[0049] In this embodiment, similarly to the above-described permanent electromagnetic holder 10, the sensitivity and position of the reed switch 16 are determined so that the reed switch 16 is closed only when the object to be attracted 100 (see FIG. 1) is attracted to the attraction surface 140a, and the reed switch 16 is open when the object to be attracted 100 is separated even slightly. Therefore, in the permanent electromagnetic holder 10a according to this embodiment, it is possible to determine whether the object to be attracted 100 is attracted to the attraction surface 140a by detecting whether the reed switch 16 is open or closed.

[0050] Although detailed description will be omitted, the configuration of the magnetic force generating unit is not limited to the above example. The magnetic force generating unit may include at least a coil, a first magnet that is magnetized in a first direction along the axial direction of the coil or a second direction opposite to the first direction depending on the direction of current flow through the coil, and a second magnet whose magnetization direction is fixed, and may be configured to operate the reed switch 16, and various known permanent electromagnetic holder configurations may be used. [Industrial Applicability]

[0051] According to the present invention, a permanent electromagnetic holder capable of determining the attraction state of an object to be attracted with a simple configuration is obtained. [Explanation of symbols]

[0052] 10,10a Permanent electromagnetic holder 12 Magnetic force generating unit 14,140 York 14a,140a Adsorption surface 16 Reed Switch 20 Coil 22 First magnet 24 Second Magnet 45,47 Cavity

Claims

1. a magnetic force generating unit including a coil, a first magnet that is magnetized in a first direction along an axial direction of the coil or a second direction opposite to the first direction depending on a direction of current flow through the coil, and a second magnet whose magnetization direction is fixed; a yoke portion that houses the magnetic force generating portion and has an attraction surface that attracts an object to be attracted; a reed switch provided in the yoke portion and operated based on the magnetic flux generated by the magnetic force generating portion, the attraction surface is switched between a state in which it is attracted to the attraction target and a state in which it is not attracted to the attraction target depending on a magnetization direction of the first magnet, The reed switch is in a closed state when the object to be attracted is attracted to the attraction surface, and is in an open state when the object to be attracted is not attracted to the attraction surface.

2. the second magnet has a cylindrical shape, is arranged coaxially with the coil, and is magnetized in a direction along the axial direction of the coil, The first magnet is provided inside the coil and the second magnet in a radial direction of the coil, the attraction surface is provided on one side of the first magnet and the second magnet in the axial direction of the coil, The permanent electromagnetic holder according to claim 1 , wherein the reed switch is provided outside the coil and the second magnet in the radial direction.

3. a cylindrical non-magnetic portion provided within the yoke portion so as to surround the second magnet; the non-magnetic portion is provided so as to extend to the attraction surface, the attraction surface includes a first region on an inner side of the non-magnetic portion in the radial direction and a second region on an outer side of the non-magnetic portion in the radial direction, The permanent electromagnetic holder according to claim 2 , wherein the reed switch is provided radially outwardly of the non-magnetic portion.

4. 4. The permanent electromagnetic holder according to claim 3, wherein the reed switch is held by the yoke portion such that the length direction of the reed switch is aligned with the axial direction of the coil.

5. 5. The permanent electromagnetic holder according to claim 4, wherein the reed switch is held in a cavity formed in the yoke portion.

6. 6. The permanent electromagnetic holder as described in claim 5, wherein the hollow portion includes a pair of guide surfaces facing both ends of the reed switch in the radial direction, and a concave surface provided between the pair of guide surfaces and recessed from the pair of guide surfaces in a direction away from the reed switch in the radial direction.

7. 4. The permanent electromagnetic holder according to claim 2, wherein at least a portion of the reed switch is located on the one side of the coil in the axial direction relative to the first magnet and the second magnet.

8. a plurality of the magnetic force generating units arranged to be aligned in a radial direction of the coil; The permanent electromagnetic holder according to claim 1 , wherein the yoke portion houses the plurality of magnetic force generating parts.

9. The permanent electromagnetic holder according to claim 8 , wherein the reed switch is provided between adjacent ones of the magnetic force generating parts.

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