Electromagnetic Brake Device

Abstract

To provide an electromagnetic brake device which saves electric power while stably exerting strong braking force.SOLUTION: An electromagnetic brake device 1 comprises a brake disc 400, a fixed disc 500, an armature 300, a biasing member 200 that biases the armature, and a stator 100 that attracts the armature. A stator magnetic path member 105 has a U shape including a first yoke 110, a permanent magnet 130, and a second yoke 120, which are arranged in this order from one end to the other end of the U shape. In a rotatable state and a rotationally braked state, coil energization is turned off to maintain the rotatable state and the rotationally braked state. The electromagnetic brake device is configured to shift to the rotationally braked state when a current of a predetermined magnitude in a first direction is caused to flow to a coil 150 in the rotatable state and to shift to the rotatable state when a current of a predetermined magnitude in a second direction is caused to flow to the coil 150 in the rotationally braked state.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a self-holding electromagnetic brake device. [Background technology]

[0002] Electromagnetic brake devices are known as devices that brake the movement of a rotating shaft (such as a motor shaft or a wheel axle) of an object to be braked (such as a motor or a vehicle). A conventional electromagnetic brake device (non-excitation type), as described in Patent Documents 1 to 3, for example, comprises a brake disc that is rotatable integrally with a rotating shaft and slidable along the central axis of the rotating shaft, a fixed disc arranged coaxially opposite one side of the brake disc, an armature arranged coaxially opposite the other side of the brake disc and slidable along the central axis, a coil spring that presses the armature in the direction in which the brake disc is arranged, and an electromagnet consisting of a coil and a yoke that is arranged on the side of the armature opposite the side on which the brake disc is arranged and is capable of generating a magnetic force that attracts the armature in a direction away from the brake disc.

[0003] In a conventional electromagnetic brake device (non-excitation type), when the electromagnet is not excited, the armature is urged by the urging force of the coil spring, and as a result, the brake disc is sandwiched between the armature and the fixed disc while in contact with each other, thereby braking the rotation of the rotating shaft. On the other hand, when the electromagnet is excited, a magnetic force is generated from the electromagnet, attracting the armature, which moves toward the stator against the urging force of the coil spring, releasing the brake disc from contact with the armature and the fixed disc, allowing the rotating shaft to rotate freely.

[0004] However, with conventional electromagnetic brake devices (non-excitation type), it is necessary to keep current flowing through the coil of the electromagnet at all times when the device is in a freely rotatable state, which means that the device cannot be said to be energy-efficient.

[0005] To solve these problems, a so-called "self-holding" electromagnetic brake device has been proposed, which does not use a coil spring and consumes power only when transitioning between the brake's activated state and its inactivated state (freely rotatable state) (see, for example, Patent Document 4). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Utility Model Application Publication No. 57-122836 [Patent Document 2] JP 2010-144852 A [Patent Document 3] JP 2019-199957 A [Patent Document 4] Japanese Patent Application Publication No. 9-229105 Summary of the Invention [Problem to be solved by the invention]

[0007] Fig. 6 is a diagram showing the configuration of an electromagnetic brake device 900 described in Patent Document 4. Although a detailed explanation will be omitted for the electromagnetic brake device described in Patent Document 4, the armature is of the Robin type, and therefore has the following problems.

[0008] (a) The second flange portion 932 near one end 961 and the other end 962 of the stator magnetic path member 960, which is the location on the magnetic circuit that contributes to switching between the operating and non-operating states of the brake (also called the point of force), and the brake abutment surface 931a of the first flange portion 931, which is the location that contributes to braking the rotating part by pressing against the hub 916 (also called the point of application), are physically separated. Therefore, it is not necessarily possible to obtain a strong braking force like that of the non-excitation operating type electromagnetic brake device described above. (b) Since the armature 930 is of the Robin type, the first flange portion 931 and the second flange portion 932 are destined to restrict the movement of each other. Therefore, when the brake contact surface 931a on the first flange portion 931 side is brought into contact with the friction material 913 to activate the brake, the second flange portion 932 side must have an air gap 9b between the other side surface 932b of the second flange portion 932 and the other end 962 of the stator magnetic path member 960. In addition, an air gap 9a is also present on the opposite side of the second flange portion 932. Therefore, the air gaps 9a and 9b increase the magnetic resistance on the magnetic circuit, and the magnetic flux passing through the air gaps 9a and 9b decreases, and as a result, a sufficient attraction force cannot be obtained. Therefore, a strong braking force cannot be obtained. (c) When the friction material 913 wears, the air gap 9b decreases and may eventually become 0 (zero). When this happens, the pressing force against the hub 916 weakens, and the braking force cannot be stably exerted. (d) Since the armature 930 needs to move in a direction parallel to the central axis AX, it is necessary to ensure a clearance 9c between the permanent magnet 933 and the end of the second flange portion 932 (not shown). Note that reference numerals 934 shown on both sides of the permanent magnet 933 are spacers and do not function as yokes. It is the stator magnetic path member 960 and the second flange portion 932 that function as yokes when viewed from the permanent magnet 933. Since the clearance 9c is required in this way, the magnetic resistance in the magnetic circuit increases, and the magnetic flux passing through decreases accordingly, and as a result, a sufficient attractive force cannot necessarily be obtained. Therefore, a strong braking force cannot necessarily be obtained.

[0009] The present invention has been made in consideration of the above circumstances, and has an object to provide an electromagnetic brake device that is energy-efficient while stably exerting a strong braking force. [Means for solving the problem]

[0010] According to one aspect of the present invention, there is provided an electromagnetic brake device for braking the movement of a rotating shaft of an object to be braked, comprising: a brake disc that can rotate integrally with a rotating shaft and can slide along the central axis of the rotating shaft; a fixed disc that is arranged coaxially opposite to one side of the brake disc; an armature that is arranged coaxially opposite to the other side of the brake disc and can slide along the central axis; a biasing member that presses the armature in the direction in which the brake disc is arranged; and a stator that is arranged on the side of the armature opposite to the side on which the brake disc is arranged and is capable of generating a magnetic force that attracts the armature in a direction away from the brake disc. Here, the stator has a coil and a stator magnetic path member including a first yoke, a permanent magnet, and a second yoke. The stator magnetic path member has a substantially U-shape surrounding the coil when viewed in cross section along a plane including the central axis, and is disposed so that one end face at one end of the U-shape and the other end face at the other end face face the armature. The elements of the stator magnetic path member are disposed in this order from one end to the other end of the U-shape: the first yoke, the permanent magnet, and the second yoke. The electromagnetic brake device is configured such that (i) in a freely rotatable state in which the rotating shaft is free to rotate, even though current to the coil is turned off, the armature maintains a state in which it abuts against one end face and the other end face of the stator magnetic path member; (ii) in the freely rotatable state, when a current of a predetermined magnitude in a first direction is passed through the coil, the armature moves toward the brake disc and abuts against the brake disc, transitioning to a rotational braking state in which the rotation of the rotating shaft is braked; (iii) in the rotational braking state, even though current to the coil is turned off, the brake disc maintains a state in which it is abutting and sandwiched between the armature and the fixed disc; and (iv) in the rotational braking state, when a current of a predetermined magnitude is passed through the coil in a second direction opposite to the first direction, the armature moves toward the stator, and the brake disc is released from abutment between the armature and the fixed disc, transitioning to the freely rotatable state.

[0011] According to another aspect of the present invention, the electromagnetic brake device is configured so that (a) in a freely rotatable state in which the rotating shaft is free to rotate, the magnitude of the force that attracts the armature by the magnetic circuit having a permanent magnet as a magnetomotive force source exceeds the magnitude of the force (biasing force) that biases the armature by the biasing member, (b) when transitioning from the freely rotatable state to a rotational braking state in which rotation of the rotating shaft is braked, the magnitude of the force that attracts the armature by the magnetic circuit having a permanent magnet and a coil as a magnetomotive force source falls below the magnitude of the biasing force, (c) in the rotational braking state, the magnitude of the force that attracts the armature by the magnetic circuit having a permanent magnet as a magnetomotive force source falls below the magnitude of the biasing force, and (d) when transitioning from the rotational braking state to the freely rotatable state, the magnitude of the force that attracts the armature by the magnetic circuit having a permanent magnet and a coil as a magnetomotive force source exceeds the magnitude of the biasing force. Effect of the Invention

[0012] According to the present invention, it is possible to provide an electromagnetic brake device that is energy-saving while stably exerting a strong braking force. [Brief description of the drawings]

[0013] [Figure 1] 1 is a perspective view of an electromagnetic brake device 1 according to an embodiment. [Diagram 2] 2 is a cross-sectional view of the electromagnetic brake device 1 according to the embodiment taken along the line AA in FIG. 1(a) when two imaginary planes indicated by PL1 and PL2 in FIG. [Diagram 3] 2 is a diagram for explaining the function of the electromagnetic brake device 1 according to the embodiment. FIG. [Figure 4] 1 is a graph showing the force (attraction force fsc) with which the stator 100 attracts the armature 300 and the force (spring force fsp) with which the biasing member 200 biases the armature 300 in relation to the position of the armature 300. [Diagram 5] 4 is an enlarged cross-sectional view of a main portion of an electromagnetic brake device 2 according to a modified example. FIG. [Figure 6]FIG. 1 is a diagram showing the configuration of an electromagnetic brake device 900 described in Patent Document 4. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, an embodiment of an electromagnetic brake device according to the present invention will be described with reference to the drawings. Each drawing is a schematic diagram showing an example, and does not necessarily strictly reflect the actual dimensions, ratios, etc.

[0015] 1. Configuration of the electromagnetic brake device 1 according to the embodiment (1) Overview of Electromagnetic Brake Device 1 The electromagnetic brake device 1 according to the embodiment is an electromagnetic brake device that brakes the movement of a rotating shaft (such as a motor shaft or a wheel axle) of an object to be braked (such as a motor or various vehicles) not shown.

[0016] FIG. 1 is a perspective view of an electromagnetic brake device 1 according to an embodiment. FIG. 1(a) is a diagram showing the external appearance of the electromagnetic brake device 1, and FIG. 1(b) is a diagram showing the electromagnetic brake device 1 disassembled along the central axis line AX of a rotating shaft (shaft 700). Lead wires are omitted from FIG. 1. FIG. 2 is a cross-sectional view of the electromagnetic brake device 1 according to the embodiment, taken along the arrow A, with two imaginary planes (imaginary planes including the bolt screw 630, the central axis line AX, and the coil spring 200) shown by PL1 and PL2 in FIG. 1(a) unfolded. FIG. 2 shows the electromagnetic brake device 1 in a rotation braking state. Ribs, shafts, bearings, etc. are omitted from the illustration.

[0017] 1 and 2, the electromagnetic brake device 1 includes a stator 100, an armature 300, a brake disc 400, and a fixed disc 500, which are arranged in this order from left to right in the drawing along a central axis AX of a rotating shaft (shaft 700). A coil spring 200 serving as a biasing member is disposed in a spring hole 125 of the stator 100 (see Figs. 1(b) and 2). Incidentally, the rotating shaft (shaft 700) is not necessarily an essential component of the electromagnetic brake device 1, but is shown together with other components in Fig. 1 for ease of understanding. Below, the shaft will sometimes be referred to as the rotating shaft 700, and the rotating shaft will sometimes be referred to as the shaft 700. Similarly, the coil spring will sometimes be referred to as the biasing member 200, and the biasing member will sometimes be referred to as the coil spring 200. These terms are interchangeable.

[0018] When using the electromagnetic brake device 1, for example, the stator 100 may be fixed to an appropriate fixed portion (such as a fixed portion of an object to be braked), the shaft 700 of the object to be controlled may be inserted into an opening 612 of a hub 610 (described later), and the shaft 700 may be fixed to the hub 610 by a bolt screw through a screw hole (not shown). Also, when the shaft 700 is inserted in advance into the hub 610 of the electromagnetic brake device 1 as shown in Fig. 1, the shaft 700 may be connected to the rotating portion of the object to be braked using a coupling or the like. The electromagnetic brake device 1 is fixed and connected to an object to be braked as described above, and when a current of a predetermined magnitude in an intended direction is applied to a coil 150 (described later) from the outside through lead wires (not shown), the armature 300 moves (details will be described later). Note that "fixed and connected" here may be a direct fixed and connected, or an indirect fixed and connected via another part.

[0019] The brake disc 400 rotates together with the hub 610 and the rotating shaft 700 around the central axis AX. When the armature 300 moves toward the fixed disc 500 and pinches the brake disc 400 together with the fixed disc 500 while abutting against it, the movement of the brake disc 400 is braked by the frictional forces between the armature 300 and the fixed disc 500. This indirectly brakes the movement of the rotating shaft 700 (the rotation is decelerated, the rotation is stopped, and the movement in the rotational direction is restricted). On the other hand, when the armature 300 moves toward the stator 100, the brake disc 400 is released from the abutment by the armature 300 and the fixed disc 500 and becomes free to rotate. Accordingly, the rotating shaft 700 also becomes free to rotate indirectly.

[0020] Below, the details of each component of the electromagnetic brake device 1 will be described, focusing on the structure. (2) Brake disc 400 The brake disc 400 is rotatable integrally with the rotating shaft 700 and is slidable along the central axis AX of the rotating shaft 700. The brake disc 400 is generally ring-shaped and has a friction surface that contacts the fixed disc 500 on one side and a friction surface that contacts the armature 300 on the other side. The brake disc 400 includes a spacer disc 410 and brake pads 420 arranged on both sides of the spacer disc 410 so as to sandwich the spacer disc 410 therebetween. The brake pad 420 is in the shape of a ring of a certain width, one surface of which is closely fixed to the spacer disk 410, and the other surface (surface) of which forms the above-mentioned friction surface. The brake pad 420 is desirably made of a material having a relatively high friction coefficient and high durability. The width of the brake pad 420 is much narrower than that of the spacer disk 410. The spacer disk 410 is in the shape of a ring, and has a substantially rectangular opening 412 in the center that conforms to the contour shape of the hub 610 (described later) (see FIG. 1(b)). The spacer disk 410 may be made of either a non-magnetic material or a soft magnetic material. In addition, the brake pads 420 may be omitted from the brake disc 400, and the brake disc 400 may be formed only by the spacer disc 410.

[0021] (3) Hub 610 Hub 610 has a central through hole, and shaft 700 can be inserted through opening 612 of the central through hole. The inserted shaft 700 can be fixed to hub 610 with a fixing screw (not shown). The outer shape of the hub 610 is a substantially square prism, but the four corners are formed into a contour shape that is substantially the same as a circular arc centered on the central axis AX, which is the center of the central through-hole (strictly speaking, it does not have to be a perfect circular arc, but may be a shape that is simply chamfered with straight lines), so as to match with the opening of the opening 412 of the spacer disk 410 described above. The outer dimensions of the hub 610 having this substantially square contour shape are set slightly smaller than the dimensions of the opening 412 of the spacer disk 410 described above, so that the hub 610 can be fitted into the opening 412 of the spacer disk 410 described above. Because the spacer disc 410 (and thus the brake disc 400) and the hub 610 have this kind of relationship, the brake disc 400 is constrained by the hub 610 in the rotational direction and rotates integrally with the hub 610 (and thus the rotating shaft 700). On the other hand, in the thrust direction, the brake disc 400 is able to slide along the central axis AX.

[0022] (4) Fixed disk 500 Fixed disc 500 is disposed coaxially opposite one side of brake disc 400. Fixed disc 500 is generally ring-shaped with an opening in the center, and has an opening 512 that allows shaft 700, hub 610, etc. to escape and not interfere with them. The side of the fixed disc 500 on which the brake disc 400 is arranged has a friction surface (not shown) that comes into contact with the brake disc 400. The fixed disc 500 has three countersunk holes 510 spaced at 120° intervals, and bolt screws 630 can be inserted into the countersunk holes 510 from the side opposite to the side on which the friction surface of the fixed disc 500 is provided. The bolt screw 630 passes through the inner hole 642 of the cylindrical collar 640 and screws into the screw hole 124 provided in the stator 100 (the second yoke 120 on the outer periphery), thereby fixing the fixed disk 500 to the stator 100 while maintaining a separation distance determined by the height of the collar 640.

[0023] (5) Armature 300 The armature 300 is disposed coaxially opposite to the other side of the brake disc 400. The armature 300 is made of a soft magnetic material. The armature 300 is generally ring-shaped with an opening in the center, and has an opening 312 that allows the shaft 700, hub 610, etc. to escape and not interfere with them. The side of the armature 300 where the brake disc 400 is disposed has a friction surface (not shown) that comes into contact with the brake disc 400. The surface opposite to the surface on which the friction surface is provided has a contact surface that comes into contact with a yoke (110, 120) of the stator 100, which will be described later, a surface that receives the urging force of the coil spring 200, which will be described later, and the like. Further, a notch 320 is provided on the outer circumferential edge of the armature 300 at a position corresponding to the above-mentioned collar 640. Collar 640 is loosely engaged with the notch 320, so that when the armature 300 moves due to the biasing force of the coil spring 200 or the attractive force of the stator 100 (details will be described later), the armature 300 is guided by the collar 640 via the notch 320 and can slide in the thrust direction along the central axis AX.

[0024] (6) Coil spring 200 (biasing member) The coil spring 200 as a biasing member is dropped into a circular concave spring hole 125 provided in the second yoke 120 of the stator 100 described later, with one end thereof abutting and being restricted by a spring wall 125a which forms the bottom of the spring hole 125, and the other end protruding from the spring hole 125 along the central axis AX in the direction of the armature 300 and abutting against the armature 300 (see FIG. 2). As the armature 300 moves, the other end of the coil spring 200 can also expand and contract along the central axis AX toward the side where the armature 300 is disposed. The coil spring 200 as a biasing member presses the armature 300 in the direction in which the brake disc 400 is disposed. In this specification, the term "biasing" refers to pressing the armature 300 in the direction in which the brake disc 400 is disposed, and this pressing force is referred to as the "biasing force f sp or spring force f sp " In the embodiment, the coil spring 200 is taken as the biasing member, but the biasing member is not limited to this. For example, the biasing member may be realized by a leaf spring, an appropriate actuator, or the like.

[0025] (7) Stator 100 The stator 100 is disposed on the opposite side of the armature 300 from the side on which the brake disc 400 is disposed, and is capable of generating a magnetic force that attracts the armature 300 in a direction away from the brake disc. In this specification, the force that attracts the armature 300 is referred to as an "attraction force f sc 2, the stator 100 generally includes a coil 150, and a stator magnetic path member 105 including a first yoke 110, a permanent magnet 130, and a second yoke 120.

[0026] (7-1) The coil 150 excites members constituting a magnetic circuit (described in detail later), such as the stator magnetic path member 105 and the armature 300, by supplying current of a predetermined magnitude in an intended direction from the outside via lead wires (not shown). The coil 150 may be obtained by using a bobbin 140 and winding an electric wire around the central axis line AX along the rail of the bobbin 140. The bobbin 140 is made of an insulating material.

[0027] (7-2) When viewed in cross section along a plane including the central axis AX (as in FIG. 2), the stator magnetic path member 105 has a substantial U-shape surrounding the coil 150, and is disposed such that one end face 112 at one end of the U-shape and the other end face 122 at the other end face face the armature 300. The elements of the stator magnetic path member 105 are disposed in the following order from one end (the side closer to the rotation axis) to the other end (the side farther from the rotation axis) of the U-shape described above: the first yoke 110 (inner yoke), the permanent magnet 130, and the second yoke 120 (outer yoke).

[0028] It is preferable that the permanent magnet 130 is disposed on one end side of the U-shape close to the central axis AX of the rotating shaft 700 and in a position close to one end face.

[0029] Here, the cross-sectional shape of the stator magnetic path member 105 is "generally U-shaped" in the sense that one end face 112 on one end side and the other end face 122 on the other end side face the armature 300, and the member connecting the one end face 112 and the other end face 122 is closed and continuous without any particular air gap, and to this extent, the "generally U-shaped" here also includes shapes close to the letter C or the letter V. Here, the "stator magnetic path member 105" refers to a general member constituting a magnetic circuit (described in detail later), and is a concept that includes permanent magnets as well as yokes. The first yoke 110 and the second yoke 120 are made of a soft magnetic material.

[0030] (7-3) The cross-sectional shape of the stator magnetic path member 105 is as described above, but the stator magnetic path member 105 as a whole has a generally ring-like or generally cylindrical shape with an opening in the center (see Fig. 2 and Fig. 1(b)). A ball bearing (not shown) is embedded in the opening 102 of the stator magnetic path member 105, and the outer ring of the ball bearing is fixed to the stator magnetic path member side, while the inner ring of the ball bearing is fixed to the shaft 700.

[0031] (7-4) The second yoke 120 also has a generally ring-shaped or cylindrical shape with an opening at the center, and is formed with an annular groove 121 that opens toward the armature 300. The wall of the second yoke 120 near the outer periphery (closer to the RD direction) that forms the annular groove 121 constitutes the "other end" of the stator magnetic path member 105, and the surface of this other end that faces the armature 300 is the "other end surface 122" of the stator magnetic path member 105. The other end surface 122 is the surface that abuts against the armature 300. The width of the other end surface 122 is set smaller (narrower) than the width of the second yoke 120 other than the other end surface 122 (the width of the wall near the outer periphery). The annular groove 121 accommodates a coil 150 together with a bobbin 140 . The wall closer to the center (closer to the -RD direction) that forms the annular groove 121 is one step lower than the wall closer to the outer periphery (closer to the RD direction), and a ring-shaped permanent magnet 130 is stacked on this lower step closer to the center, and a ring-shaped first yoke 110 is stacked on top of that, sandwiching the permanent magnet 130 between the second yoke 120 and the first yoke 110. A circular concave spring hole 125 is formed in the second yoke 120. Also, a screw hole 124 that can be combined with a bolt screw 630 and screwed into is formed in the second yoke 120.

[0032] (7-5) The permanent magnet 130 has a slightly flattened ring shape, and can be magnetized, for example, so that one surface is a north pole and the other surface is a south pole. The permanent magnet 130 is arranged such that the magnetic axis connecting the positive magnetic pole (N pole) and the negative magnetic pole (S pole) of the permanent magnet 130 coincides with the stacking direction of the first yoke 110, the permanent magnet 130, and the second yoke 120 (the left - right direction in FIG. 2). In an example of the embodiment, the positive magnetic pole (N pole) appears on the side where the fixed disk 500 is arranged (the side where the first yoke 110 on the right side of FIG. 2 is stacked), and the permanent magnet 130 is arranged such that the negative magnetic pole (S pole) appears on the opposite side (the side where the second yoke 120 on the left side of FIG. 2 is stacked). Note that the arrangement of the positive magnetic pole and the negative magnetic pole may be reversed as long as it is consistent with the control of the energization of the coil 150 described later.

[0033] (7 - 6) The first yoke 110 has a substantially ring - shaped overall configuration with a central opening. On the side facing the armature 300, the central part is one step lower than the edge closer to the outer periphery, forming a substantially cup - shaped configuration. The edge part closer to the outer periphery constitutes the "one end" of the stator magnetic path member 105, and its end face is the "one - end face 112" of the stator magnetic path member 105. The one - end face 112 is the face that abuts against the armature 300.

[0034] (7 - 7) The width W2 of the one - end face 112 is set to be smaller (narrower) than the overall width of the first yoke 110 including the one - end face 112 (substantially the same as the width W1 of the permanent magnet 130 in this example). Also, when viewing the cross - section of the electromagnetic brake device 1 in a plane including the central axis AX, when the width of the permanent magnet 130 in the direction perpendicular to the central axis AX is W1, and the width of the one - end face 112 of the first yoke 110 or the other - end face 122 of the second yoke 120 in the direction perpendicular to the central axis AX is W2, it is configured such that W2 < W1. Further, it is more preferable to configure it such that W2 < (W1 / 2).

[0035] 2. Functions of the Electromagnetic Brake Device 1 According to the Embodiment Next, the function of the electromagnetic brake device 1 will be sequentially described with reference to FIGS. 3 - 4. Fig. 3 is a diagram for explaining the function of the electromagnetic brake device 1 according to the embodiment. Fig. 3(a), Fig. 3(c), Fig. 3(e) and Fig. 3(g) are enlarged cross-sectional views of main parts corresponding to the first to fourth phases, respectively. Note that each component in this figure is shown diagrammatically and therefore has different dimensions, ratios, etc. from each component in Fig. 1 and Fig. 2. Fig. 3(b), Fig. 3(d), Fig. 3(f) and Fig. 3(h) show diagrams of magnetic circuits equivalent to the electromagnetic brake device 1 corresponding to the first to fourth phases, respectively.

[0036] (1) Magnetic circuit equivalent to electromagnetic brake device 1 First, before explaining the function of the electromagnetic brake device 1, a magnetic circuit equivalent to the electromagnetic brake device 1 will be explained. Since the electromagnetic brake device 1 has the structure described above, it forms one closed "magnetic circuit." The "magnetic circuit" refers to a circuit formed by the path of the N pole of the permanent magnet 130, the first yoke 110, the air gap AG between the one end face 112 and the armature 300, the armature 300, the air gap AG between the armature 300 and the other end face 122, the second yoke 120, and the S pole of the permanent magnet 130, with the permanent magnet 130 and the coil 150 as magnetomotive force sources. However, the orientation of the magnetic poles is assumed to be in the case of the magnetic pole arrangement of the permanent magnet 130 exemplified above. Here, the magnetomotive force of the permanent magnet 130 is F mg Let the magnetomotive force of the coil be F c The magnetic resistance of the first yoke 110, the armature 300, and the second yoke 120 among the magnetic resistances of the paths constituting the magnetic circuit (i.e., the same as the total resistance in the state where the armature 300 is in contact with the one end surface 112 and the other end surface 122 of the stator magnetic path member 105) is R CON When the armature 300 is separated from the stator 100 and an air gap AG is generated even slightly, the magnetic resistance of the air gap AG is R. AG and the magnetic flux passing through the magnetic circuit is Φ (see FIG. 2 and FIG. 3 described later). In this embodiment, F mg is constant, and F cchanges depending on the direction and magnitude of the current flowing through the coil, and R CON is assumed to be constant, and R AG is assumed to vary depending on the size of the air gap AG, and Φ (subscripts are added according to the phase numbers) is assumed to vary depending on the state.

[0037] (1-1) Magnetic circuit of the first phase As shown in FIG. 3(a), when the armature 300 is completely attracted to the stator 100, the rotating shaft is free to rotate. This state is called the "freely rotatable state." In the free-rotatable state, if no current flows through the coil 150, the equivalent magnetic circuit is as shown in FIG. 3(b), and the magnetomotive force is F mg (magnetic circuit with permanent magnet as magnetomotive force source). Since the air gap AG is 0 (zero), R AG becomes 0 (zero), and the total magnetic resistance is R CON At this time, the magnetic flux is Φ1.

[0038] (1-2) Magnetic circuit of the second phase As shown in FIG. 3(c), when a current of a predetermined magnitude flows through the coil 150 in a first direction (here, from the front surface of the paper to the back surface of the paper) in the first phase of free rotation, the armature 300 starts to move toward the brake disc 400 (arrow B). The magnetic circuit equivalent to this state is as shown in FIG. 3(d). The magnetomotive force in this circuit is F by the permanent magnet 130. mg and the magnetomotive force F of the permanent magnet mg The magnetomotive force F by coil 150 in the direction of decreasing c The total magnetomotive force is F mg -F c (A magnetic circuit with a permanent magnet and coil as magnetomotive force sources.) Since an air gap AG is created, R AG The total magnetic resistance changes from 0 to a value, R CON +R AG The magnetic flux at this time is Φ2. The value of the magnetic flux Φ2 at this time is smaller than the value of the magnetic flux Φ1. Therefore, the attractive force fsc It is generally known that the larger the air gap in a magnetic circuit, the smaller the attractive force acting on the armature. This is because when the air gap is large, the magnetic resistance of the entire magnetic circuit increases, which reduces the magnetic flux passing through the air gap AG and reduces the attractive force.

[0039] (1-3) Third phase magnetic circuit As shown in Fig. 3(e), when the armature 300 presses against the brake disc 400 and the brake disc 400 is completely sandwiched between the armature 300 and the fixed disc 500 while being in contact with each other, the rotation of the rotating shaft is braked. This state is referred to as the "rotation braking state." In the rotation braking state, when no current is applied to the coil 150, the equivalent magnetic circuit is as shown in Fig. 3(f), and the magnetomotive force is F mg (magnetic circuit with permanent magnet as magnetomotive force source). The magnetic resistance corresponding to the air gap AG is R AG is the maximum air gap AG max The total magnetic resistance is R CON +R AG(AG=AGmax) The magnetic flux at this time is Φ3. Generally, Φ3≦Φ2≦Φ1.

[0040] (1-4) Magnetic circuit of the fourth phase As shown in FIG. 3(g), when a current of a predetermined magnitude flows through the coil 150 in a second direction (here, from the rear surface of the paper to the front surface of the paper) opposite to the first direction in the third phase rotation braking state, the armature 300 starts to move toward the stator 100 (arrow C). The magnetic circuit equivalent to this state is as shown in FIG. 3(h). The magnetomotive force in this circuit is F by the permanent magnet 130. mg and the magnetomotive force F of the permanent magnet mg The magnetomotive force F by the coil 150 in the direction of c The total magnetomotive force is F mg +F c(A magnetic circuit with a permanent magnet and coil as the magnetomotive force source.) The air gap AG is decreasing but still remains, so R AG The total magnetic resistance is R CON +R AG The magnetic flux at this time is Φ4. The value of the magnetic flux Φ4 at this time is greater than the value of the magnetic flux Φ3. Therefore, the attractive force f sc This is the opposite of the second phase, because when the air gap becomes smaller, the magnetic resistance of the entire magnetic circuit becomes smaller, and as a result, the magnetic flux passing near the air gap AG increases, strengthening the attractive force.

[0041] (2) Specifications of Electromagnetic Brake Device 1 As can be seen from the structure around the armature 300 (see Figs. 2 and 3), the behavior and state of the armature 300 are determined by the "spring force f sp " and "attraction force f" due to magnetic flux Φ generated by the magnetic circuit (strictly speaking, magnetic flux Φ passing between the armature 300 and the one end surface 112 and / or the other end surface 122 of the stator magnetic path member 105). sc " It can be understood that this is determined by the combination of " and ". Here, the spring strength (spring constant, spring position (spring compression amount), magnetomotive force of the permanent magnet, magnetomotive force of the coil, magnetic permeability of the yoke, and maximum air gap AG max The "parameters" such as the above can be appropriately set as long as the functions and effects of the present invention are achieved. In this embodiment, for example, the spring force f sp , suction force f sc These "parameters" are set to configure the electromagnetic brake device 1 so as to generate the above-mentioned torque (details will be explained next).

[0042] (3) Spring force f sp , suction force f sc Relationship between the Armature 300 and the Movement FIG. 4 shows the force with which the stator 100 attracts the armature 300 (attraction force f sc ) and the force exerted by the biasing member 200 on the armature 300 (spring force fsp ) on the vertical axis and the position of the armature 300 on the horizontal axis, the two-dot chain line indicated by the symbol D in the positive region of the vertical axis represents the spring force f sp Size and attractive force f sc The absolute value of the spring force |f is shown in order to compare the magnitude of the force in the unsigned state. sp The curve in the graph indicates the phase transition direction. The position of the armature 300, which is the horizontal axis in the graph, can be said to be the distance between the yoke (first yoke 110, second yoke 120) and the armature 300, and specifically corresponds to the air gap AG between the surface of the armature 300 on the stator 100 side and one end face 112 and / or the other end face 122 of the stator magnetic path member 105. Hereinafter, the spring force f in the electromagnetic brake device 1 will be referred to as sp , suction force f sc The relationship between the above and the movement of the armature 300 will be further described with reference to FIG. 4 (also with reference to FIG. 3).

[0043] (3-1) First phase (self-maintaining free rotation state) The first phase is a phase in which the freely rotatable state is maintained. In the graph, when the electromagnetic brake device 1 is in the first phase (AG=0), the coordinate (0,f sc1 ) is located above the coordinate of the absolute value of the spring force shown by curve D by Δf1. In other words, in a rotatable state in which the rotating shaft 700 is free to rotate, the force (attraction force) f sc1 The magnitude of the force (spring force or biasing force) f applied to the armature 300 by the biasing member 200 is sp1 It exceeds the size of In the first phase, the current to the coil 150 is turned off. In the magnetic circuit in the first phase, the only magnetomotive force source is the permanent magnet 130. sc However, the magnetic attraction force generally changes depending on the position of the armature (generally, the smaller the air gap AG, the smaller the magnetic resistance RAG By making good use of this, and optimizing the specifications, the attractive force f by the permanent magnet 130 alone can be achieved. sc Only the spring force f sp It can be configured to exceed

[0044] In this way, in the first phase, even though the current to the coil 150 is turned off, the magnetic attraction force fsc is equal to the spring force f sp 10, the armature 300 is always attracted to the side of the stator 100, and the armature 300 is maintained in contact with one end surface 112 and the other end surface 122 of the stator magnetic path member 105.

[0045] (3-2) Second phase (transition from free rotation state to rotation braking state) The second phase is a phase in the process of transition from the first phase (free rotation state) to the third phase (rotation braking state). In the first phase state, when a current of a predetermined magnitude flows through the coil 150 in a first direction (see FIG. 3(c)), the magnetomotive force F of the permanent magnet is generated as described above. mg The magnetomotive force F by coil 150 in the direction of decreasing c The total magnetomotive force after synthesis is F mg -F c As a result, the attractive force f sc is being weakened. When moving from the first phase to the second phase, the attraction force weakens due to the above principle, and the coordinates taken by the attraction force in the first phase become (0,f sc1 ) was temporarily changed to (0,f sc2 ) At this time, the absolute value of the spring force |f sp1 | is the suction force f sc2 As a result, the armature 300 is moved away from the stator 100 (the air gap AG also increases accordingly). As described above, the attractive force varies depending on the position of the armature, so the attractive force f scchanges along the curve E of the graph as the armature 300 moves (as AG changes). On the other hand, the spring force f sp Since the spring force f changes depending on the amount of compression of the spring, sp The force f also changes along the line H of the graph as the armature 300 moves. When the rotational braking state is reached and the air gap widens to the point where the armature 300 cannot move any further, the attractive force f sc The coordinates taken by (AG max ,f sc3 During this time, the attractive force f sc (Curve E) is always lower than the absolute value of the spring force (Curve D).

[0046] In other words, when the rotation of the rotating shaft 700 is transited from the freely rotatable state to the rotation braking state in which the rotation of the rotating shaft 700 is braked (second phase), the magnitude of the force attracting the armature 300 by the magnetic circuit having the permanent magnet 130 and the coil 150 as the magnetomotive force source (attraction force f sc ) is the biasing force (spring force f sp ) is smaller than the size of the

[0047] In other words, the electromagnetic brake device 1 is configured such that, when a current of a predetermined magnitude in a first direction is passed through the coil 150 in a freely rotatable state, the armature 300 moves toward the brake disc 400 and abuts against the brake disc 400, transitioning to a "rotational braking state" in which the rotation of the rotating shaft 700 is braked.

[0048] (3-3) Third phase (self-maintaining the rotational braking state) The third phase is a phase in which the rotational braking state is maintained. In the graph, when the electromagnetic brake device 1 is in the third phase (AG=AG max When the attraction force is max ,f sc4 ) is located below the coordinate of the absolute value of the spring force shown by curve D by Δf2. In other words, in the rotation braking state, the force (attraction force) f sc4The magnitude of the biasing force (spring force) f sp2 is below the size of

[0049] In this way, in the third phase, the electromagnetic brake device 1 maintains the spring force f even though the current to the coil 150 is turned off (see FIG. 3(e) and FIG. 3(f)). sp is the suction force f sc 4. The brake disc 400 is configured to always exceed the armature 300 and the fixed disc 500 so as to maintain a state in which the brake disc 400 is sandwiched between the armature 300 and the fixed disc 500 while being in contact with each other.

[0050] (3-4) Fourth phase (transition from rotation braking state to free rotation state) The fourth phase is a phase in the process of transition from the third phase (rotation braking state) to the first phase (free rotation state). In the third phase state, when a current of a predetermined magnitude is passed through the coil 150 in a second direction (see FIG. 3(c)) opposite to the first direction, the magnetomotive force F of the permanent magnet is generated as described above. mg The magnetomotive force F by the coil 150 in the direction of c The total magnetomotive force after synthesis is F mg +F c As a result, the attractive force f sc is being strengthened. When moving from the third phase to the fourth phase, the attraction force becomes stronger due to the above principle, and the coordinate taken by the attraction force in the first phase becomes (AG max ,f sc4 ) was once (AG max ,f sc5 ) At this time, the attractive force f sc5 Absolute value of spring force |f sp2 |, the armature 300 approaches the stator 100 (and the air gap AG decreases accordingly). As described above, the attractive force changes depending on the position of the armature, so the attractive force f sc changes along the curve G of the graph as the armature 300 moves (as AG changes). On the other hand, the spring force f spSince the spring force f changes depending on the amount of compression of the spring, sp The magnetic force f also changes along the line H of the graph as the armature 300 moves. When the armature 300 comes into complete contact with the stator 100 and cannot move any further, the air gap disappears and the magnetic force f sc The coordinates taken by are (0,f sc6 During this time, the attractive force f sc (Curve G) always exceeds the absolute value of the spring force (Curve D).

[0051] In other words, when the rotation of the rotating shaft 700 is transited from the rotation braking state to the free rotation state in which the rotation of the rotating shaft 700 is braked (fourth phase), the magnitude of the force attracting the armature 300 by the magnetic circuit having the permanent magnet 130 and the coil 150 as the magnetomotive force source (attraction force f sc ) is the biasing force (spring force f sp ) in size.

[0052] In other words, the electromagnetic brake device 1 is configured such that, when a current of a predetermined magnitude is passed through the coil 150 in a second direction opposite to the first direction in a rotational braking state, the armature 300 moves toward the stator 100, and the brake disc 400 is released from contact between the armature 300 and the fixed disc 500, transitioning to a "freely rotatable state."

[0053] (3-5) In addition, in the electromagnetic brake device 1, the magnetomotive force of the permanent magnet 130, the spring constant of the biasing member 200, and the displacement of the biasing member 200 are set so that Δf2>Δf1. Here, "the displacement of the biasing member 200 is set" can be said to mean, for example, that the magnitude of contraction of the coil spring 200 is set. Specifically, the depth of the spring hole 125, the AG max This means that the dimensions of the

[0054] However, in the freely rotatable state (first phase), the magnitude of the force that attracts the armature 300 by the magnetic circuit using the permanent magnet 130 as a magnetomotive force source is |f sc1| and the magnitude of the force |f applied to the armature 300 by the biasing member 200 sp1 The magnitude of the force that attracts the armature 300 by the magnetic circuit using the permanent magnet 130 as a magnetomotive force source in the rotation braking state (third phase) is |f sc4 | and the magnitude of the force |f applied to the armature 300 by the biasing member 200 sp2 | is taken as Δf2 (see Figure 4).

[0055] (3-6) Also, as can be seen from Figure 4, the spring force f sp The curve H(0,f sp1 )~(A.G. max ,f sp2 ) than the slope of the attractive force f sc The curve E(0, f sc2 )~(A.G. max ,f sc3 ) or curve G(AG max ,f sc5 )~(0,f sc6 That is, in the electromagnetic brake device 1, the inclination of the biasing force f by the biasing member 200 relative to the displacement (horizontal axis) of the armature 200 is larger. sp The parameters are set so that the rate of change of the attractive force fsc by the stator 100 is higher than the rate of change of the magnetic flux density Fs.

[0056] As can be understood from the above description, in the electromagnetic brake device 1 according to the embodiment, the force applied to the armature 300 can be roughly divided into the biasing force (spring force f sp ) and the attractive force (f sc ) and the attractive force (f sc ) is capable of generating an attractive force with the permanent magnet 130 as a magnetomotive force source and an attractive force with the coil 150 as a magnetomotive force source. On the other hand, the magnetomotive force F mg is generated as a fixed bias (the attractive force from the permanent magnet 130 is always generated to some extent). On the other hand, the magnetomotive force F from coil 150c Regarding the magnetomotive force F, by appropriately controlling the current supply to the coil (controlling the current supply / non-current supply (OFF) to the coil 150, controlling the direction of the current flow such as the first direction / second direction when the current is supplied, and controlling the magnitude of the current, etc.), the magnetomotive force F mg It is now possible to control how the sound occurs according to intention.

[0057] For this reason, in the electromagnetic brake device 1 according to the embodiment, the magnetic resistance R varies depending on the position of the armature 300 (depending on the size of the air gap AG). AG By making good use of the fact that the force f changes, the spring force f sp In order to achieve self-holding, the magnetic pole is configured to have a magnetic pole larger than the magnetic pole f and to have a magnetic pole f that is larger than the magnetic pole f. sc By strengthening (superimposing) or weakening the biasing force f sp It is possible to make it exceed or fall below the limit.

[0058] 3. Effects of the electromagnetic brake device 1 according to the embodiment (1) The electromagnetic brake device 1 according to the embodiment includes the biasing member 200 that presses the armature 300 in the direction in which the brake disc 400 is disposed, and is configured as described above, so that in the rotation braking state, the biasing force of the biasing member 200 mainly contributes to braking. For this reason, compared to a conventional self-holding type electromagnetic brake device that relies solely on the magnetomotive force of a permanent magnet to move the armature for braking (see Patent Document 4), it is possible to stably exert a stronger braking force.

[0059] In the electromagnetic brake device 1, the stator magnetic path member 105 further includes a permanent magnet 130 in addition to the yokes (first yoke 110, second yoke 120). A magnetic circuit using this permanent magnet 130 as a magnetomotive force source is configured to be able to maintain the armature 300 in contact with one end surface 112 and the other end surface 122 of the stator magnetic path member 105 in a freely rotatable state even when the current supply to the coil 150 is turned off. As a result, the electromagnetic brake device of the present invention does not require current to constantly flow through the coil in a freely rotatable state, as in conventional non-excitation operated electromagnetic brake devices (see Patent Documents 1 to 3), making it an electromagnetic brake device that consumes less power than conventional devices.

[0060] As described above, the electromagnetic brake device 1 according to this embodiment is energy-efficient while stably exerting a strong braking force.

[0061] (2) The electromagnetic brake device 1 according to the embodiment includes the above-described biasing member 200, and the stator 100 includes, in addition to the coil 150, the permanent magnet 130 as a component of the stator magnetic path member 105. At this time, the electromagnetic brake device 1 is configured such that "in the freely rotatable state, the magnitude of the force that attracts the armature 300 by the magnetic circuit using the permanent magnet 130 as a magnetomotive force source exceeds the magnitude of the force that biases the armature 300 by the biasing member 200," and "in the rotation braking state, the magnitude of the force that attracts the armature 300 by the magnetic circuit using the permanent magnet 130 as a magnetomotive force source is less than the magnitude of the biasing force." Therefore, it is possible to maintain the freely rotatable state and the rotationally braked state without passing a current through the coil 150, resulting in a power-saving electromagnetic brake device.

[0062] In addition, in the rotation braking state, the biasing force of the biasing member 200 mainly contributes to braking. Therefore, compared to a conventional self-holding type electromagnetic brake device that relies only on the magnetomotive force of a permanent magnet to move the armature for braking (see Patent Document 4), a stronger braking force can be stably exerted.

[0063] In addition, the electromagnetic brake device 1 of the embodiment is also configured so that "when transitioning from the freely rotatable state to the rotational braking state, the magnitude of the force attracting the armature 300 by the magnetic circuit using the permanent magnet 130 and the coil 150 as magnetomotive force sources becomes smaller than the magnitude of the biasing force," and "when transitioning from the rotational braking state to the freely rotatable state, the magnitude of the force attracting the armature 300 by the magnetic circuit using the permanent magnet 130 and the coil 150 as magnetomotive force sources exceeds the magnitude of the biasing force." This makes it possible to use the magnetomotive force of the coil as a lever, so to speak, to move the armature toward the brake disc or toward the stator, allowing the armature to move freely between a freely rotatable state and a rotationally braking state.

[0064] As described above, the electromagnetic brake device 1 according to this embodiment is energy-efficient while stably exerting a strong braking force.

[0065] (3) The permanent magnet 130 is disposed on one end side of the U-shape close to the central axis AX of the rotating shaft 700 (the side of the first yoke 110 ), and at a position close to the one end face 112 . In this way, by arranging the permanent magnet 130, which is the magnetic force source, in a position close to the central axis AX, it is expected that a strong attractive force will be generated in a position closer to the rotating shaft 700, and more stable braking will be obtained. Also, by arranging the permanent magnet 130 in a position closer to the one end face 112, it is expected that a relatively large magnetic flux will be generated from a position close to the surface that abuts against the armature 300 (one end face 112), and the armature can be attracted efficiently.

[0066] (4) When the width of the permanent magnet 130 in the direction perpendicular to the central axis AX is W1 and the width of one end face 112 of the first yoke 110 or the other end face 122 of the second yoke 120 in the direction perpendicular to the central axis AX is W2, it is configured such that W2 < W1. For this reason, since the width W2 of the one end face 112 or the other end face 122, which is the surface through which the magnetic flux is passed to the armature 300 side, is made narrower than the width W1 of the permanent magnet 130 serving as the magnetomotive force source, the magnetic flux Φ can be induced with a narrow width to increase the magnetic flux density, and the armature can be attracted efficiently. Furthermore, this effect can be further enhanced by setting W2 < (W1 / 2).

[0067] (5)|f sc1 | and |f sp1 | and the difference therebetween is defined as Δf1, and when the difference between |f sc4 | and |f sp2 | is defined as Δf2, the magnetomotive force of the permanent magnet 130, the spring constant of the biasing member 200, and the displacement of the biasing member 200 are set such that Δf2 > Δf1. In other words, the force Δf2 with which the armature contacts the brake disk in the rotation braking state is set to be greater than the force Δf1 with which the armature contacts the first yoke and / or the second yoke in the rotatable state. For this reason, the electromagnetic brake device 1 according to the embodiment can stably exhibit a stronger braking force.

[0068] (6) The brake disk 400 includes a spacer disk 410 and brake pads 420 disposed on both surfaces of the spacer disk 410 so as to sandwich the spacer disk 410.

[0069] The brake disc 400 may be formed only by the spacer disc 410 without disposing the brake pads 420. In this case, the contact between the brake disc 400 and the armature 300 and between the brake disc 400 and the fixed disc 500 are metal-to-metal contacts. Therefore, when the armature 300 hits the brake disc 400 to brake the rotation, the friction surface may be irregularly scraped, and the friction state may easily fluctuate, making it difficult to obtain stable friction. On the other hand, if the brake pads 420 are disposed on both sides of the spacer disc 410 as in the embodiment, the above-mentioned problems do not occur and stable friction can be obtained.

[0070] Although the present invention has been described based on the above embodiment, the present invention is not limited to the above embodiment. It can be embodied in various forms without departing from the spirit of the present invention, and for example, the following modifications are also possible.

[0071] (1) The numbers, materials, shapes, positions, sizes, and other elements of the components described in the above embodiments are merely examples and may be changed without impairing the effects of the present invention.

[0072] (2) In the example described in the embodiment, the permanent magnet 130 is disposed on one end side of the U-shape close to the central axis AX of the rotating shaft 700 and close to the one end face 112. However, the present invention is not limited to this. For example, as shown in FIG. 5, the permanent magnet 130' may be disposed on the other end side of the U-shape farther from the central axis AX of the rotating shaft (not shown) and close to the other end face. Note that FIG. 5 is an enlarged cross-sectional view of a main part of the electromagnetic brake device 2 according to a modified example, and corresponds to FIG. 3(a). [Explanation of symbols]

[0073] 1,2,900...electromagnetic brake device, 100...stator, 102...(stator) opening, 105,960...stator magnetic path member, 110...first yoke (inner peripheral yoke), 112...(one end surface of one end of the U-shape), 120...second yoke (outer peripheral yoke), 121...groove, 122...(other end surface of the U-shape), 124...screw hole, 125...spring hole, 125a...spring wall, 130,130',933...permanent magnet, 140...bobbin, 150...coil, 200...biasing member (coil spring), 300,930...armature, 312...(armature) opening, 320...cutting Notch, 400...Brake disc, 410...Spacer disc, 412...Opening (of brake disc), 420...Brake pad, 500...Fixed disc, 510...Countersink, 512...Opening (of fixed disc), 610, 916...Hub, 612...Opening (of hub), 630...Bolt screw, 640...Collar, 642...Inner hole, 700...Rotating shaft (shaft), 913...Friction material, 931...First flange portion, 931a...Brake contact surface, 932...Second flange portion, 932b...Surface (on the other side), 961...One end (of stator magnetic path member), 962...The other end (of stator magnetic path member)

Claims

1. An electromagnetic brake device that brakes the movement of a rotating shaft of a braking object, a brake disc that is rotatable integrally with the rotating shaft and is slidable along a central axis of the rotating shaft; A fixed disc disposed coaxially opposite one side of the brake disc; an armature disposed coaxially opposite the other side of the brake disc and slidable along the central axis; a biasing member that biases the armature toward the brake disc; a stator that is disposed on a side of the armature opposite to a side on which the brake disc is disposed, and that is capable of generating a magnetic force that attracts the armature in a direction away from the brake disc, the stator includes a coil, a first yoke, a permanent magnet, and a second yoke. the stator magnetic path member has a substantially U-shape surrounding the coil when viewed in cross section along a plane including the central axis, and is disposed such that one end face on one end side and the other end face on the other end side of the U-shape face the armature, The elements of the stator magnetic path member are arranged in the order of the first yoke, the permanent magnet, and the second yoke from one end to the other end of the U-shape, in the U-shaped stator magnetic path member, a portion for narrowing a width of the first yoke or the second yoke from a first width to a second width smaller than the first width is provided at a position closer to the armature than a center position of the coil when viewed along the central axis, The electromagnetic brake device is In a rotatable state in which the rotating shaft is freely rotatable, the armature maintains a state in which it is in contact with the one end surface and the other end surface of the stator magnetic path member even though the current to the coil is turned off, When a current of a predetermined magnitude in a first direction is applied to the coil in the freely rotatable state, the armature moves toward the brake disc and comes into contact with the brake disc, transitioning to a rotation braking state in which the rotation of the rotating shaft is braked, In the rotation braking state, the brake disc is held in a state of being sandwiched between the armature and the fixed disc while the current to the coil is turned off, When a current of a predetermined magnitude flows through the coil in a second direction opposite to the first direction in the rotation braking state, the armature moves toward the stator, and the brake disc is released from contact between the armature and the fixed disc, and transitions to the freely rotatable state. Electromagnetic brake device.

2. An electromagnetic brake device that brakes the movement of a rotating shaft of a braking object, a brake disc that is rotatable integrally with the rotating shaft and is slidable along a central axis of the rotating shaft; A fixed disc disposed coaxially opposite one side of the brake disc; an armature disposed coaxially opposite the other side of the brake disc and slidable along the central axis; a biasing member that biases the armature toward the brake disc; a stator that is disposed on a side of the armature opposite to a side on which the brake disc is disposed, and that is capable of generating a magnetic force that attracts the armature in a direction away from the brake disc, the stator includes a coil, a first yoke, a permanent magnet, and a second yoke. the stator magnetic path member has a substantially U-shape surrounding the coil when viewed in cross section along a plane including the central axis, and is disposed such that one end face on one end side and the other end face on the other end side of the U-shape face the armature, The elements of the stator magnetic path member are arranged in the order of the first yoke, the permanent magnet, and the second yoke from one end to the other end of the U-shape, in the U-shaped stator magnetic path member, a portion for narrowing a width of the first yoke or the second yoke from a first width to a second width smaller than the first width is provided at a position closer to the armature than a center position of the coil when viewed along the central axis, The electromagnetic brake device is In a rotatable state in which the rotating shaft is free to rotate, a force that attracts the armature by a magnetic circuit using the permanent magnet as a magnetomotive force source exceeds a force that biases the armature by the biasing member, When the rotating shaft transitions from the freely rotatable state to a rotation braking state in which the rotation of the rotating shaft is braked, the magnitude of the force attracting the armature by a magnetic circuit having the permanent magnet and the coil as a magnetomotive force source becomes smaller than the magnitude of the biasing force, In the rotation braking state, the magnitude of the force attracting the armature by the magnetic circuit using the permanent magnet as a magnetomotive force source is less than the magnitude of the biasing force, When the rotation braking state transitions to the freely rotatable state, a force that attracts the armature by a magnetic circuit having the permanent magnet and the coil as a magnetomotive force source exceeds a force of the biasing force. Electromagnetic brake device.

3. 3. The electromagnetic brake device according to claim 1, a difference between a force that attracts the armature by a magnetic circuit using the permanent magnet as a magnetomotive force source in the rotatable state and a force that biases the armature by the biasing member is defined as Δf1; When the difference between the force with which the armature is attracted by the magnetic circuit using the permanent magnet as a magnetomotive force source and the force with which the armature is biased by the biasing member in the rotation braking state is Δf2, The magnetomotive force of the permanent magnet, the spring constant of the biasing member, and the displacement of the biasing member are set so that Δf2>Δf1. Electromagnetic brake device.

4. In the electromagnetic brake device according to claim 1 or 2, the permanent magnet is disposed on the side of the one end of the U-shape close to the central axis of the rotating shaft and in a position close to the one end face, Electromagnetic brake device.

5. In the electromagnetic brake device according to claim 1 or 2, When the electromagnetic brake device is cut in a cross section along a plane including the central axis, the width of the permanent magnet in a direction perpendicular to the central axis is defined as W. １ and the width of the one end surface of the first yoke or the other end surface of the second yoke in a direction perpendicular to the central axis is W ２ When W ２ <W １ It is configured to be Electromagnetic brake device.

6. 6. The electromagnetic brake device according to claim 5, ２ <(W １ / 2).

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