Coil unit

Abstract

To provide a coil unit that can suppress magnetic loss caused by short circuits of magnetic flux.SOLUTION: A coil unit 2 is used to attract an object to be attracted 6 by magnetic force, and includes a yoke 3 made of a magnetic material, a coil 4 formed by directly winding a conducting wire around the yoke 3, and a coil support portion 5 attached to the end of the yoke 3 on the side of the object to be attracted 6, which is made of a non-magnetic and insulating material and supports the coil 4 by contact.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a coil unit used to attract an object to be attracted by magnetic force. [Background technology]

[0002] Conventionally, there has been a demand for compact electromagnetic brakes with coil units for use in industrial and medical robots, with diameters of less than 30 mm, for example.Such compact electromagnetic brakes are achieved by directly winding the coil around the yoke.

[0003] For example, as shown in FIG. 7 , the electromagnetic brake of Patent Document 1 has an annular recess 50A formed in an inner pole member 50 serving as an inner yoke, and a coil 54 formed by direct winding of a conductor around the annular recess 50A. When current is applied to the coil 54, an armature 55 is attracted against the biasing force of a braking spring 57 serving as a biasing means, thereby allowing rotation of a motor shaft 56. Conversely, when current is cut off to the coil 54, the braking spring 57 presses the armature 55 against a brake disc 58, thereby stopping rotation of the motor shaft 56. Note that FIG. 7 shows a state in which current is applied to the coil 54 after current is cut off, i.e., a state in which the braking spring 57 presses the armature 55 against the brake disc 58, and then the coil 54 is energized. When current is applied to the coil 54, a magnetic path is formed, causing the armature 55 to move toward the inner pole member 50 against the biasing force of the braking spring 57.

[0004] The inner electrode member 50 includes a cylindrical portion 51, a first flange portion 52 protruding radially outward from one axial end side of the cylindrical portion 51, and a second flange portion 53 protruding radially outward from the other axial end side (the armature 55 side) of the cylindrical portion 51. The inner electrode member 50 is made of a magnetic material, and a small gap is formed between an outer end 53A of the second flange portion 53 of the inner electrode member 50 and an inner surface 59A of an outer electrode member 59 serving as an outer yoke.

[0005] As a result, the magnetic force generated by energizing the coil 54 flows from one axial end of the outer pole member 59 located outside the first flange portion 52 of the inner pole member 50 to the other axial end, resulting in a short circuit of magnetic flux. The magnetic force is dispersed into a first magnetic path G1 passing through the armature 55, through which the magnetic force should flow, and a second magnetic path G2 passing through the second flange portion 53 of the inner pole member 50. As a result, the magnetic force passing through the second flange portion 53 of the inner pole member 50 becomes magnetic loss, resulting in a decrease in the attractive force that attracts the armature 55. While the second flange portion 53 of the inner pole member 50 is formed so that its radial thickness becomes thinner toward the radial outside to reduce the magnetic loss, the formation of a magnetic path through the second flange portion 53 through which the magnetic force passes has not been completely resolved, leaving room for improvement. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2018-182250 A (see Figure 4) Summary of the Invention [Problem to be solved by the invention]

[0007] Therefore, an object of the present invention is to provide a coil unit that can suppress magnetic loss due to short-circuiting of magnetic flux. [Means for solving the problem]

[0008] The coil unit of the present invention is a coil unit used to attract an object to be attracted by magnetic force, and comprises a yoke formed from a magnetic material, a coil formed by winding a conducting wire directly around the yoke, and a coil support part attached to the end of the yoke facing the object to be attracted, which is made of a non-magnetic and insulating material and supports the coil by abutting against the end.

[0009] According to the present invention, the coil support portion, which is made of a non-magnetic and insulating material, is attached to the end of the yoke facing the object to be attracted, thereby preventing short circuits of magnetic flux from occurring at the end of the yoke.

[0010] In the coil unit of the present invention, the coil support portion may be made of resin.

[0011] As described above, the coil support portion can be formed from a general material (resin).

[0012] In the coil unit of the present invention, the coil support portion may have a recessed groove into which a lead wire connected to the coil is fitted.

[0013] As described above, by providing the recessed grooves into which the lead wires are fitted, the lead wires can be bundled together in the coil unit.

[0014] In addition, in the coil unit of the present invention, the coil support portion may be annular, have an inner dimension smaller than the outer dimension of the end of the yoke facing the object to be attracted, and be attached to the yoke by press-fitting.

[0015] According to the above configuration, the coil support portion can be firmly attached to the yoke by press-fitting the coil support portion into the yoke. [Effects of the Invention]

[0016] According to the present invention, a coil unit can be provided that is formed from a non-magnetic and insulating material and has a coil support part that supports a series-wound coil by abutment, thereby suppressing magnetic loss due to short-circuiting of magnetic flux. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a cross-sectional view of a non-excitation actuation type electromagnetic brake including a coil unit according to an embodiment of the present invention. [Figure 2] FIG. 2 is a perspective view of a coil support portion provided in the coil unit. [Figure 3] FIG. 4 is a cross-sectional view of the non-excitation actuation type electromagnetic brake, showing a state in which the armature is pressed against the braking portion by the biasing force of the biasing portion when not energized. [Figure 4] 10A and 10B show another form of the coil support part provided in the coil unit, where (a) is a front view and (b) is a plan view. [Figure 5] 10A and 10B show another form of the coil support part provided in the coil unit, where (a) is a front view and (b) is a plan view. [Figure 6] 10A and 10B show another form of the coil support part provided in the coil unit, where (a) is a front view and (b) is a plan view. [Figure 7] FIG. 1 is a cross-sectional view of a conventional non-excitation actuation type electromagnetic brake. DETAILED DESCRIPTION OF THE INVENTION

[0018] An embodiment of a non-excitation actuation type electromagnetic brake (hereinafter simply referred to as an electromagnetic brake) 1 equipped with a coil unit 2 according to the present invention will be described with reference to the drawings.

[0019] As shown in FIG. 1, the electromagnetic brake 1 includes a coil unit 2 having a yoke 3, a coil 4, and a coil support portion 5, an armature 6 which is an object to be attracted, a biasing portion 7, a braking portion 8, and a fixed portion 9.

[0020] The yoke 3 includes an outer yoke 31 located on the outside and an inner yoke 32 arranged inside the outer yoke 31. The outer yoke 31 and the inner yoke 32 are made of a ferromagnetic material such as iron.

[0021] The outer yoke 31 includes a cylindrical peripheral wall portion 31A that accommodates the inner yoke 32, and a plurality (four in this embodiment) of plate-shaped locking pieces 31B that extend from multiple circumferential locations (four in this embodiment) on the other axial end (the right end in FIG. 1 ) of the peripheral wall portion 31A toward a side spaced apart in the axial direction (the right side in FIG. 1 ). These locking pieces 31B are engaged with recesses 6A (described below) formed at multiple circumferential locations (four in this embodiment) on the armature 6 and grooves 9A (described below) formed at multiple circumferential locations (four in this embodiment) on the fixed portion 9. This configuration allows the outer diameters of the armature 6 and the fixed portion 9 to be the same or approximately the same as the outer dimensions of the outer yoke 31. This allows the electromagnetic brake 1 to be made smaller without degrading braking performance.

[0022] The inner yoke 32 includes a cylindrical main body 32A around which a conductor (not shown) is wound in series, and a flange 32B that protrudes radially outward from one axial end of the main body 32A and supports one axial end of the wound conductor. Surfaces 32a and 32b of the inner yoke 32 with which the wound conductor comes into contact are insulated with insulating tape, insulating paint, or the like. A bearing 11 is provided inside the flange 32B of the inner yoke 32 to rotatably support one end of the braked rotating shaft 10 (the left end in FIG. 1). The outer end of the flange 32B contacts the inner surface of the peripheral wall 31A of the outer yoke 31.

[0023] The coil 4 is formed by directly winding a conductor around the insulated inner yoke 32 as described above. Direct winding refers to winding a conductor around the yoke, rather than attaching a separately formed coil to the yoke.

[0024] The coil support portion 5 is attached to the end of the main body portion 32A of the inner yoke 32 on the armature 6 side, and is made of resin (a common material), which is an example of a non-magnetic and insulating material, but may also be made of synthetic rubber, etc. As shown in Figures 1 and 2, the coil support portion 5 is configured as an annular, so-called bobbin-shaped portion that opens radially outward and includes a cylindrical portion 5A extending in the axial direction and a pair of disk portions 5B, 5C extending radially outward from both axial ends of the cylindrical portion 5A.

[0025] The other axial end 4A of the coil 4 abuts against the first circular plate 5B of the pair of circular plates 5B, 5C, which is closer to the coil, thereby supporting the other axial end of the coil 4. The first circular plate 5B also functions as a positioning member when the conductor is directly wound around the yoke. The cylindrical portion 5A and the pair of circular plates 5B, 5C form a groove 5M into which the lead wire 12 connected to the coil 4 is fitted. The groove 5M allows the lead wire 12 to be bundled together in the groove 5M. After fitting the lead wire 12 into the groove 5M, the gap may be filled with a resin such as silicone. This stabilizes the retention of the lead wire 12. The first circular plate 5B of the pair of circular plates 5B, 5C, which is closer to the coil 4, has two notches 5K, 5K formed therein for inserting the lead wire 12 into the groove 5M. The lead wire 12 accommodated in the groove 5M is extracted to the outside through a through-hole 31K formed in the peripheral wall 31A of the outer yoke 31.

[0026] A protruding portion 5T protruding radially inward is formed between the axially intermediate portion of the cylindrical portion 5A of the coil support portion 5 and the end on the armature 6 side. The inner dimension of this protruding portion 5T is smaller than the outer dimension of the end of the main body portion 32A of the inner yoke 32 on the armature 6 side. Therefore, by press-fitting the coil support portion 5 into the main body portion 32A of the inner yoke 32, the coil support portion 5 can be firmly attached to the main body portion 32A of the inner yoke 32. Reducing the inner dimension of only a portion of the cylindrical portion 5A of the coil support portion 5 in the axial direction (the protruding portion 5T) of the cylindrical portion 5A of the coil support portion 5 as described above, rather than reducing the inner dimension over the entire axial length of the cylindrical portion 5A of the coil support portion 5, reduces press-fit resistance during press-fitting, thereby improving workability. In addition, chamfering the corners of the cylindrical portion 5A on the coil side makes it easier to press-fit the coil support portion 5. In addition, chamfering the corners of the cylindrical portion 5A on the coil side also has the following effects. That is, as described above, after insulating surfaces 32a and 32b of inner yoke 32 with insulating tape, when coil support portion 5 is subsequently assembled, coil support portion 5 catches on the coil support portion-side end of the insulating tape, and the coil support portion-side end of the insulating tape can fit between surface 32a and the chamfered portion of cylindrical portion 5A so as to prevent the insulating tape from being pushed up and causing wrinkles. Note that protrusion 5T of cylindrical portion 5A and the chamfered portion of cylindrical portion 5A may be provided on the main body portion 32A side.

[0027] The armature 6 is made of a ferromagnetic material such as iron, and has recesses 6A formed at four circumferential positions for engaging with the four locking pieces 31B of the outer yoke 31 described above. By engaging the recesses 6A of the armature 6 with the locking pieces 31B of the outer yoke 31, the armature 6 is supported so as to be unrotatable relative to the outer yoke 31 and to be movable in the axial direction. A through hole 6K is formed in the radial center of the armature 6, through which the braked rotating shaft 10 is rotatably inserted. In addition, an annular protrusion 6T that abuts against the braking portion 8 is formed on the surface of the armature 6 facing the braking portion 8.

[0028] The biasing portion 7 is composed of a compression coil spring housed in a plurality of recesses 32C (eight in this embodiment, but one may be sufficient) formed at circumferentially spaced locations on the other axial end of the main body portion 32A of the inner yoke 32. When the current to the coil 4 is cut off, the biasing force of the biasing portion (compression coil spring) 7 moves the armature 6 toward the braking portion 8, pressing the braking portion 8 against the fixed portion 9 and stopping the rotation of the braking portion 8. This also stops the rotation of the braked rotating shaft 10.

[0029] The braking portion 8 has a rectangular hole 8A that fits into the rectangular shaft portion 10A of the braked rotating shaft 10, and is composed of a circular disk that rotates integrally with the braked rotating shaft 10 and is movable in the axial direction.

[0030] The fixed portion 9 is made of a cylindrical member, and has four grooves 9A formed at predetermined intervals on its outer circumferential surface. Four locking pieces 31B of the outer yoke 31 engage with these four grooves 9A, thereby fixing the fixed portion 9 to the outer yoke 31 so as to be unrotatable and unmovable in the axial direction. A bearing 13 is provided inside the fixed portion 9 to rotatably support the other axial end of the braked rotating shaft 10. In addition, an annular protrusion 9T is formed on the surface of the fixed portion 9 facing the braking portion 8, protruding toward the braking portion 8. This protrusion 9T is provided so as to come into contact with the braking portion 8 near its outer circumferential edge, and is configured to be at approximately the same radial position and have approximately the same area as the protrusion 6T formed on the armature 6.

[0031] In the electromagnetic brake 1 of this embodiment configured as described above, when the current to the coil 4 is cut off, the biasing force of the biasing portion 7 moves the armature 6 away from the inner yoke 32 (the side indicated by the arrow), as shown in FIG. 3 . This pinches the braking portion 8 between the armature 6 and the fixed portion 9, thereby stopping the rotation of the braked rotating shaft 10. On the other hand, when the current is applied to the coil 4, the magnetic force of the coil 4 moves the armature 6 toward the inner yoke 32 against the biasing force of the biasing portion 7, as shown in FIG. 1 . This causes the braking portion 8 to move away from the fixed portion 9 and the armature 6. This allows the braked rotating shaft 10 to rotate. At this time, by forming the coil support portion 5 from a nonmagnetic and insulating material, it is possible to prevent a short circuit of the magnetic flux from occurring at the end of the inner yoke 32 on the side of the object to be attracted (armature 6). As a result, as shown by the arrows in Figure 1, the magnetic force generated in the coil 4 moves from the flange portion 32B of the inner yoke 32 to the outer yoke 31, and the magnetic force that moves from one axial end (left end in Figure 1) of the outer yoke 31 to the other axial end (right end in Figure 1) passes through the object to be attracted (armature 6) and moves to the main body portion 32A of the inner yoke 32, forming one circulating magnetic path.

[0032] The present invention is not limited to the above-described embodiment, and various modifications are possible without departing from the spirit of the present invention.

[0033] For example, the coil support portion 5 may be formed from a single member, as shown in FIGS. 4(a) and (b), 5(a) and (b), and 6(a) and (b). In FIGS. 4(a) and (b), the coil support portion 5 is formed from a ring-shaped, plate-like resin member, and spring portions 5D having elastic restoring force are integrally formed at multiple circumferential locations (four locations in the figure) and protruding toward the armature 6. Therefore, when not energized, the spring portions 5D protrude toward the armature 6 due to their elastic restoring force, moving the armature 6 away from the inner yoke 32. When energized, the magnetic force of the coil 4 moves the armature 6 toward the inner yoke 32 against the elastic restoring force of the spring portions 5D. Also, in FIGS. 5(a) and (b), the coil support portion 5 is formed from a ring-shaped, plate-like resin member, and is provided with a protruding piece 5E protruding radially outward at one circumferential location. This protruding piece 5E can be used as a fixing portion for bundling and fixing lead wires (not shown) connected to the coil using a cable tie or the like. Also, in Figures 6(a) and (b), a ring-shaped, plate-shaped resin member is provided with a protruding piece 5F that protrudes radially outward from one location in the circumferential direction. Two notches 5G, 5G are formed in this protruding piece 5F for locking and fixing lead wires (not shown) connected to the coil.

[0034] In the above embodiment, the coil support portion 5 is fixed to the inner yoke 32 by press-fitting, but it may also be fixed by adhesive.

[0035] In addition, in the above embodiment, the coil unit 2 is used in a non-excitation actuation type electromagnetic brake 1, but the coil unit 2 may also be used in an excitation actuation type electromagnetic brake, or the coil unit 2 may be used in various electromagnetic clutches. [Explanation of symbols]

[0036] 1... Non-excitation operated electromagnetic brake, 2... coil unit, 3... yoke, 4... coil, 4A... other axial end, 5... coil support portion, 5A... cylindrical portion, 5B, 5C... disk portion, 5D... spring portion, 5E, 5F... protrusion, 5G... notch, 5K... notch, 5M... groove, 5T... protrusion, 6... armature (object to be attracted), 6A... recess, 6K... through hole, 6T... protrusion, 7... energizing portion (compression coil spring), 8... braking portion, 8A... hole, 9... fixed portion, 9A... groove portion, 9T... protrusion, 10... braked rotating shaft, 10A... shaft portion, 11, 13... base Ring, 12...lead wire, 31...outer yoke, 31A...circumferential wall portion, 31B...locking piece, 31K...through hole, 32...inner yoke, 32A...main body portion, 32B...flange portion, 32C...recess, 32a, 32b...surface, 50...inner pole member, 50A...annular recess, 51...cylindrical portion, 52...first flange portion, 53...second flange portion, 53A...outer end, 54...coil, 55...armature, 56...motor shaft, 57...brake spring, 58...brake disc, 59...outer pole member, 59A...inner surface, G1...first magnetic path, G2...second magnetic path

Claims

1. A coil unit used to attract an object to be attracted by magnetic force, a yoke formed from a magnetic material; a coil formed by winding a conducting wire around the yoke; a coil support portion attached to the end of the yoke on the side of the object to be attracted, the coil support portion being made of a non-magnetic and insulating material and supporting the coil by contact.

2. The coil unit according to claim 1 , wherein the coil support portion is made of resin.

3. The coil unit according to claim 1 or 2, wherein the coil support portion has a recessed groove into which a lead wire connected to the coil is fitted.

4. 3. The coil unit according to claim 1, wherein the coil support portion is annular, has an inner dimension smaller than an outer dimension of the end of the yoke facing the object to be attracted, and is attached to the yoke by press-fitting.

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