JP4810931B2 - Electromagnetic clutch - Google Patents

Description

  The present invention relates to an electromagnetic clutch that selectively transmits a driving force of an input rotating body by controlling a current flowing in a coil.

  An example of an electromagnetic clutch that selectively transmits the driving force of an input rotating body that is rotationally driven is disclosed in Patent Document 1. FIG. 11 is a cross-sectional view showing the configuration of the electromagnetic clutch 200 disclosed in Patent Document 1. As shown in FIG. As shown in FIG. 11, the electromagnetic clutch 200 includes a non-rotating field portion 220, a rotatable input portion 240, and an output portion that can selectively take a state of rotating integrally with the input portion and a state of not rotating. 260.

  The output unit 260 includes a shaft 262 and a rotor 268 that is a substantially annular member and is fitted and fixed to the shaft 262. The field portion 220 includes a coil bobbin 222 that is a cylindrical member having a flange formed at the edge, a coil 224 formed by winding an electric wire around the coil bobbin 222, and an outer peripheral surface of the coil bobbin 222 and one flange of the coil bobbin 222. And a shell 226 that is loosely fitted to the shaft 262 and covers the inner peripheral surface of the annular projecting portion 222a projecting in a direction perpendicular to the surface of the flange formed on the shaft 262. is doing. The input unit 240 is a gear 242 that is loosely fitted to the rotor 268 of the shaft 262 on the opposite side of the shell 226, and a disk-shaped member having an opening at the center, and the gear 242 faces the rotor 268. And has an armature 246 secured to 242.

  At least the above-described shell 226, the portion of the shaft 262 in which the shell 226 is loosely fitted (magnetic body portion 262a), the rotor 268, and the armature 246 are made of a magnetic material such as an iron-based metal. Therefore, in the electromagnetic clutch 200, when the coil 224 is energized, a magnetic circuit is formed in the shell 226, the magnetic part 262 a of the shaft 262, the rotor 268, and the armature 246. For this reason, the armature 246 moves to the rotor 268 side and is attracted to the rotor 268. Therefore, the rotational force input to the gear 242 is transmitted to the shaft 262 via the armature 246 and the rotor 268.

Here, when the members made of the same kind of material are in contact with each other, extremely large friction is generated as compared with the case where the members made of different materials are in contact with each other. In the electromagnetic clutch 200 of Patent Document 1, a cylindrical member integrally formed with the coil bobbin 222 is formed between a portion of the shell 226 that covers the inner peripheral surface of the protruding portion 222a of the coil bobbin 222 and the magnetic body portion 262a of the shaft 262. A bearing 222b is disposed. Thereby, the shell 226 and the magnetic part 262a which are made of an iron-based metal are not in direct contact with each other. Therefore, it is possible to prevent the sliding surfaces from being abnormally worn due to contact between members made of the same kind of material and reducing the life of the clutch.
Japanese Patent Laid-Open No. 2002-48151 (FIG. 1)

  However, the bearing 222b has a large magnetic resistance on the magnetic circuit, leading to a decrease in performance of the electromagnetic clutch 200. Therefore, if the bearing 222b is thin in order to reduce the magnetic resistance, the bearing 222b is easily broken during assembly, and the yield is reduced. It is also possible to form a protective film by coating the shaft 262 with a fluororesin or the like to prevent contact with the shell 226, but it is very difficult to perform coating so that the film thickness is constant. , Manufacturing costs are high.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an electromagnetic clutch capable of preventing a decrease in life due to wear and preventing a decrease in yield and performance while suppressing manufacturing costs.

Means and effects for solving the problems

The electromagnetic clutch of the present invention includes an input rotator to which a rotational driving force is input, a shaft that is loosely fitted to the input rotator, and at least a part of which is a magnetic body made of a magnetic material, and the shaft. An output rotator having a rotor to be fitted and fixed , and a cylindrical shape extending in the axial direction in which annular flanges are formed on both edges, and a flange on the opposite side of the input rotator A coil bobbin having an annular projecting portion projecting in a direction perpendicular to the surface, a coil formed by winding an electric wire around the coil bobbin, and the rotor of the shaft opposite to the input rotating body are loosely fitted to the side, and a shell enveloping the coil bobbin in which the coil is formed, the shell and the outer cylindrical body for covering the outer peripheral surface of the coil bobbin, the Koirubo An inner cylinder covering the inner peripheral surface of the projecting portion of the coil, a bottom plate covering the side surface of the projecting portion of the coil bobbin and connecting one end surface of the outer cylindrical body and one end surface of the inner cylindrical body. and the inner peripheral surface with projections projecting toward the shaft is formed, prior Symbol the magnetic portion opposite to the of form notches in the inner cylindrical body of the shell of the shaft of the projecting portion of the coil bobbin The protrusion protrudes from the notch, and the rotor has a disc-shaped bottom plate and a cylindrical tube connected to the outer periphery of the bottom plate, and the rotor cylinder is The outer periphery of the coil bobbin is positioned so as to face the outer cylinder of the shell in the radial direction.

  According to this configuration, since the protrusion protruding from the notch formed in the shell becomes the bearing, the contact between the shell made of the magnetic material and the shaft can be prevented. Therefore, it is possible to prevent the sliding surfaces from being abnormally worn due to contact between members made of the same kind of material and reducing the life of the clutch. Moreover, compared with the case where a thin member is arrange | positioned between a shell and a shaft, the fall of the yield by a member being damaged at the time of an assembly can be prevented. Furthermore, the manufacturing cost can be reduced as compared with the case where a protective film is formed on the shaft. In addition, the portion where the notch of the shell is not formed is opposed to the magnetic body portion of the shaft without passing through a foreign substance that becomes magnetic resistance, and therefore a member that becomes magnetic resistance is disposed between the shell and the shaft. Compared to the case, it is possible to prevent a decrease in performance.

  In the electromagnetic clutch of the present invention, it is preferable that a plurality of the protrusions and the notches are formed at equal intervals along the circumferential direction of the shaft. According to this configuration, the contact between the shaft and the shell can be prevented more reliably.

In the electromagnetic clutch according to the aspect of the invention, the notch is formed on the total length of the plurality of protrusions formed on the coil bobbin along the circumferential direction of the shaft and the surface of the shell facing the magnetic body portion. It is preferable that the ratio with the total length along the circumferential direction of the shaft of the portion not formed is 1: 1 to 2. According to this configuration, it is possible to suppress a decrease in performance due to a decrease in the facing area between the shell and the magnetic part of the shaft.

  A preferred embodiment of the present invention will be described below with reference to the drawings. The electromagnetic clutch according to the present embodiment selectively transmits the driving force of the gear that is rotationally driven to the output shaft. FIG. 1 is a cross-sectional view of an electromagnetic clutch 100 according to the present embodiment. More specifically, FIG. 1 is a cross-sectional view in a plane passing through the rotation center of a shaft 69 through which the output shaft is inserted as will be described later. In the following description, the extending direction of the shaft 69 (the direction indicated by the arrow A in FIG. 1) is simply referred to as “axial direction”.

  As shown in FIG. 1, the electromagnetic clutch 100 according to the present embodiment is integrated with a field portion 20 that does not rotate, an input portion 40 that can be rotated by a driving force input from the outside, and the input portion 40. An output unit 60 that can selectively take a rotating state and a non-rotating state is provided.

  The field unit 20 includes a coil bobbin 21, a coil 27 formed by winding an electric wire such as a copper wire around the coil bobbin 21, and a shell 31 that encloses the coil bobbin on which the coil 27 is formed. Here, the field unit 20 will be described in more detail with reference to FIGS. FIG. 2 is a plan view of the coil bobbin 21 viewed from the axial direction. FIG. 3 is a cross-sectional view taken along line III-III in FIG. FIG. 4 is a perspective view of the shell 31. FIG. 5 is a perspective view of the field unit 20. However, FIG. 5 is a diagram in which a part of the field portion 20 is cut out in order to show a cross section of the field portion 20.

  As shown in FIGS. 1, 2, 3, and 5, the coil bobbin 21 is a cylindrical member having annular flanges 21a and 21b formed at both edges and extending in the axial direction, and is made of a resin material. ing. And an electric wire is wound between the flange 21a and the flange 21b, and the coil 27 is formed. More specifically, an annular projecting portion 23 is formed on one flange 21a of the coil bobbin 21 so as to project in a direction (axial direction) perpendicular to the surface of the flange 21a. The inner diameter of the protrusion 23 is larger than the inner diameter of the flange 21a, and the outer diameter is substantially equal to the outer diameter of the flange 21a. Further, a groove 23a is formed on the outer peripheral surface of the protrusion 23, and lead lines at both ends of the coil 27 are fixed in the groove 23a.

  2, 3, and 5, a cross-sectional view for fixing the coil bobbin 21 and the shell 31 to a surface (hereinafter, referred to as “side surface”) perpendicular to the axial direction of the protruding portion 23 is omitted. Two locking portions 24 that are U-shaped and protrude in the axial direction are formed. More specifically, a claw 24 a that protrudes outward from the U-shape is formed at the distal end portion of the U-shape of the locking portion 24. Further, as shown in FIGS. 1, 2, and 5, the protrusion 23 is formed with a substantially U-shaped detent 25 extending outward from the outer peripheral surface thereof. The anti-rotation portion 25 is fixed to a fixing member inside the device on which the electromagnetic clutch 100 is mounted, and prevents the field portion 20 from rotating. In addition, an opening 26 is formed on the side surface of the portion of the projecting portion 23 where the anti-rotation portion 25 is formed to draw out the lead wire fixed in the groove 23a. In addition, six rectangular protrusions 28 protruding in the direction perpendicular to the axial direction are formed on the inner peripheral surface of the protrusion 23 at equal intervals.

  As shown in FIGS. 1, 4, and 5, the shell 31 includes an outer cylindrical body 33 that covers the outer peripheral surface of the coil bobbin 21, an inner cylindrical body 35 that covers the inner peripheral surface of the protruding portion 23 of the coil bobbin 21, and an outer cylindrical body 33. Is a bottomed double cylindrical member having a bottom body 37 that covers the side surface of the protruding portion 23 of the coil bobbin 21, and is connected to one end surface of the inner cylindrical body 35. Made of magnetic material.

  As shown in FIGS. 4 and 5, the bottom body 37 is formed with two openings 38 into which the locking portions 24 formed on the coil bobbin 21 are inserted. The width of the opening 38 is wider than the U-shaped width of the portion excluding the vicinity of the distal end of the locking portion 24 and narrower than the width of the distal end portion where the claw 24a is formed. Therefore, the coil bobbin 21 and the shell 31 are completely fixed by inserting the engaging portion 24 into the opening 38 while elastically deforming the locking portion 24 in the direction of narrowing the U-shape and hooking the claw 24a on the edge portion of the opening 38. can do.

  Further, a notch 39 through which the anti-rotation portion 25 formed in the coil bobbin 21 passes is formed across the outer cylindrical body 33 and the bottom body 37. Then, as shown in FIG. 5, the leader line drawn from the opening 26 formed on the side surface of the portion where the rotation preventing portion 25 of the protruding portion 23 is formed is drawn from the shell 31 through the notch 39. .

  Further, notches 36 are formed in portions corresponding to the six protrusions 28 formed on the coil bobbin 21 of the inner cylinder 35. As shown in FIGS. 1 and 5, when the coil bobbin 21 and the shell 31 are assembled together, the projections 28 of the coil bobbin 21 are slightly formed from the surface of the inner cylinder 35 of the shell 31 through the notches 36. Protruding. As shown in FIG. 5, the total length of the projection 28 formed on the coil bobbin 21 along the circumferential direction of the shaft 69 and the circumference of the shaft 69 where the notch 36 of the inner cylinder 35 is not formed. The ratio to the total length along the direction is 1: 1.5.

  Next, the output unit 60 will be described with reference to FIG. 1 and FIGS. The output unit 60 includes a central shaft body 61 (see FIG. 6) of a cylindrical member through which an output shaft (not shown) is inserted, and an external fitting shaft body 65 (see FIG. 7) of the cylindrical member that is externally fitted to the central shaft body 61. ) And a rotor 71 (see FIG. 8) fitted and fixed to the shaft 69.

  The center shaft body 61 is made of a resin material, and has a large-diameter cylindrical portion 62 and a smaller diameter than the large-diameter cylindrical portion 62 as shown in FIG. The small-diameter cylindrical portion 63 is provided continuously to the large-diameter cylindrical portion 62 so as to be adjacent to the cylindrical portion 62. A fitting portion 63a in which a plurality of protrusions are formed in a sawtooth shape is provided at an end portion of the outer peripheral surface of the small diameter cylindrical portion 63 on the large diameter cylindrical portion 62 side. A groove 64 extending in the axial direction is formed on the inner peripheral surface of the central shaft body 61. Therefore, by inserting the output shaft formed with the projection extending in the axial direction into the central shaft body 61 so that the projection and the groove 64 formed in the central shaft body 61 are engaged, the output shaft is It can be fixed to the central shaft body 61 with respect to the rotation direction. That is, the output shaft can be rotated integrally with the central shaft body 61.

  The outer fitting shaft body 65 is made of a magnetic material such as an iron-based metal and has a small diameter cylindrical portion 66 and a larger diameter than the small diameter cylindrical portion 66 as shown in FIG. The large-diameter cylindrical portion 67 is provided continuously with the small-diameter cylindrical portion 66 so as to be adjacent to the small-diameter cylindrical portion 66. As shown in FIG. 1, the external fitting shaft body 65 has a small diameter cylindrical portion 63 of the central shaft body 61 such that the small diameter cylindrical portion 66 is adjacent to the large diameter cylindrical portion 62 of the central shaft body 61 in the axial direction. Is externally fitted. The externally fitted shaft body 65 is fixed to the central shaft body 61 so as to prevent rotation, and rotates together with the central shaft body 61.

  The rotor 71 is made of a magnetic material such as an iron-based metal. As shown in FIG. 8, the rotor 71 has a disk-like bottom body 73 and a cylindrical cylinder 75 connected to the edge of the bottom body 73. It consists of. At the center of the bottom body 73, a convex portion 77 bulging on the opposite side of the cylindrical body 75 with respect to the bottom body 73 is formed. A circular opening 77 a having a size substantially equal to the diameter of the small diameter cylindrical portion 63 is formed on the upper surface of the convex portion 77 so as to pass through the small diameter cylindrical portion 63 of the central shaft body 61. The edge portion of the opening 77 a is formed in a sawtooth shape and is fitted with a fitting portion 63 a formed in the small diameter cylindrical portion 63 of the central shaft body 61. Thereby, the center shaft body 61 and the rotor 71 are fitted and fixed.

  As shown in FIG. 1, the field portion 20 is loosely fitted to the outer fitting shaft body 65 of the output portion 60. More specifically, in the outer fitting shaft body 65, the coil 27 formed on the coil bobbin 21 is positioned in the small diameter cylindrical portion 66 of the outer fitting shaft body 65, and the inner cylinder body 35 of the shell 31 is disposed in the outer fitting shaft body 65. The field portion 20 is fitted so that the cylindrical body 75 of the rotor 71 is positioned between the outer cylindrical body 33 of the shell 31 and the outer peripheral surface of the coil bobbin 21 while facing the large-diameter cylindrical portion 67. Here, as described above, the protrusion 28 of the coil bobbin 21 protrudes from the notch 36 provided in the inner cylinder 35 of the shell 31, and this protrusion 28 serves as a bearing. The body 35 and the large-diameter cylindrical portion 67 of the outer fitting shaft body 65 are not in direct contact.

  Next, the input unit 40 will be described with reference to FIGS. The input unit 40 includes a gear 41 (see FIG. 9) to which driving force is input from the outside, and an armature 45 (see FIG. 10) fixed to the gear 41.

  The gear 41 is made of a resin material and, as shown in FIG. 9, is a substantially disk-shaped member having an opening 42 formed in the center, and a plurality of teeth 41a are formed at equal intervals on the outer peripheral surface thereof. Yes. An annular flange 41 b is formed on the edge portion of one surface of the gear 41. In addition, a cylindrical projecting portion 41c projecting in the axial direction is formed at the edge portion of the flange 41b. Further, a recess 43 is formed around the opening 42 on the surface of the gear 41 where the flange 41b is formed. Then, at the bottom of the recess 43, four arc-shaped projections 43a that protrude along the axial direction and are equal to each other are provided at equal intervals on the circumference of a circle having a diameter equal to the diameter of the four protrusions 43a. ing.

  The armature 45 is made of a magnetic material such as an iron-based metal, and is a substantially disk-shaped member having an opening 46 formed in the center as shown in FIG. Further, when viewed from a direction perpendicular to the axial direction, four locking portions 47 that are substantially U-shaped and project along the axial direction are provided continuously at the edge portion of the opening 46. These four locking portions 47 are respectively engaged with four gaps formed between the four protrusions 43 a formed on the gear 41. As a result, the gear 41 and the armature 45 are integrally assembled as the input unit 40.

  The above-described input unit 40 is loosely fitted to the shaft 69 of the output unit 60 as shown in FIG. More specifically, in the input unit 40, the armature 45 is opposed to the bottom body 73 of the rotor 71 of the output unit 60, the gear 41 is positioned at the large-diameter cylindrical portion 62 of the center shaft body 61, and the armature 45 is It is fitted to the shaft 69 so as to be positioned on the side surface of the convex portion 77 formed on the bottom body 73 of the base member 73.

  Next, the operation of the electromagnetic clutch 100 according to the embodiment configured as described above will be described. When the coil 27 is not energized, a magnetic circuit is not formed, and the armature 45 and the rotor 71 are separated from each other. Therefore, even if a driving force is input to the gear 41 from the outside, only the gear 41 and the armature 45 rotate, and the rotational force is not transmitted to the shaft 69.

  On the other hand, when the coil 27 is energized, a magnetic circuit passing through the shell 31 made of a magnetic material, the outer fitting shaft body 65 of the shaft 69, the rotor 71, and the armature 45 is formed. To be adsorbed. Thereby, the input part 40 and the output part 60 rotate integrally, and the rotational driving force input into the gear 41 from the outside is transmitted to the output shaft inserted in the central shaft body 61 of the shaft 69.

  As described above, in the electromagnetic clutch 100 according to the present embodiment, the coil bobbin 21 formed with the protrusion 28 protruding in the direction perpendicular to the axial direction, and the coil 27 formed by winding the electric wire around the coil bobbin 21. And a shell 31 made of a magnetic material, enclosing the coil bobbin 21 on which the coil 27 is formed, and having a notch 36 formed in a portion corresponding to the protrusion 28 formed on the coil bobbin 21. The non-rotating field portion 20 includes a central shaft body 61 and an outer fitting shaft body 65 made of a magnetic material and fitted on the central shaft body 61. It is loosely fitted. A projection 28 formed on the coil bobbin 21 protrudes from a surface of the shell 31 facing the outer fitting shaft body 65 through a notch 36. Therefore, since the protrusion 28 serves as a bearing, the contact between the shell 31 made of a magnetic material and the outer fitting shaft body 65 can be prevented. As a result, it is possible to prevent the sliding surfaces from being abnormally worn due to contact between members made of the same kind of material and reducing the life of the clutch. Moreover, compared with the case where a thin member is arrange | positioned between the shell 31 and the external fitting shaft body 65, the fall of the yield by a member being damaged at the time of an assembly can be prevented. Furthermore, the manufacturing cost can be reduced as compared with the case where a protective film is formed on the outer fitting shaft body 65. In addition, the portion of the shell 31 where the notch 36 is not formed is opposed to the outer fitting shaft body 65 without a foreign substance serving as a magnetic resistance, so that a magnetic force is generated between the shell 31 and the outer fitting shaft body 65. Compared with the case where a member serving as a resistor is disposed, it is possible to prevent a decrease in performance.

  In the electromagnetic clutch 100 of the present embodiment, the protrusion 28 that protrudes in the direction perpendicular to the axial direction provided on the coil bobbin 21 and the notch 36 that protrudes the protrusion 28 of the coil bobbin 21 provided on the shell 31 are Also, six are formed at equal intervals along the circumferential direction of the shaft 69. Therefore, contact between the shell 31 and the outer fitting shaft body 65 of the shaft 69 can be prevented more reliably.

  Furthermore, in the electromagnetic clutch 100 according to the present embodiment, the total length of the projection 28 formed on the coil bobbin 21 along the circumferential direction of the shaft 69 and the portion where the notch 36 of the inner cylinder 35 of the shell 31 is not formed. The ratio of the total length along the circumferential direction of the shaft 69 is 1: 1.5. Accordingly, it is possible to suppress a decrease in performance due to a decrease in the facing area between the shell 31 and the outer fitting shaft body 65 of the shaft 69.

  The preferred embodiment of the present invention has been described above. However, the present invention is not limited to the above-described embodiment, and various design changes can be made as long as they are described in the claims. Is something. For example, in the above-described embodiment, the projections 28 provided on the coil bobbin 21 and the notches 36 that project the projections 28 of the coil bobbin 21 provided on the shell 31 are all equidistant along the circumferential direction of the shaft 69. However, the number of the protrusions 28 and the notches 36 is not limited to six. Further, the protrusions 28 and the notches 36 need not be formed at equal intervals.

  Further, in the above-described embodiment, the total length of the projections 28 formed on the coil bobbin 21 along the circumferential direction of the shaft 69 and the portion of the shaft 69 where the notch 36 of the inner cylinder 35 of the shell 31 is not formed. Although the case where the ratio to the total length along the circumferential direction is 1: 1.5 has been described, the present invention is not limited to this. The ratio of the total length of the protrusions 28 to the total length of the portions of the inner cylinder 35 where the notches 36 are not formed is preferably 1: 1 to 2, but these ratios are not limited. Can be determined arbitrarily.

It is sectional drawing of the electromagnetic clutch which concerns on embodiment of this invention. It is the top view which looked at the coil bobbin shown in FIG. 1 from the extension direction of an output shaft. It is sectional drawing which follows the III-III line of FIG. It is a perspective view of the shell shown in FIG. It is a perspective view of the field part shown in FIG. It is a perspective view of the center axis | shaft body shown in FIG. It is a perspective view of the external fitting shaft body shown in FIG. It is a perspective view of the rotor shown in FIG. It is a perspective view of the gear shown in FIG. It is a perspective view of the armature shown in FIG. It is sectional drawing of the conventional electromagnetic clutch.

Explanation of symbols

21 Coil bobbin 27 Coil 28 Projection 31 Shell 36 Notch 40 Input section (input rotating body)
60 Output unit (output rotating body)
65 External fitting shaft (magnetic part)
69 Shaft 71 Rotor 100 Electromagnetic clutch

Claims (3)

An input rotating body to which rotational driving force is input;
An output rotator having a shaft on which the input rotator is loosely fitted and at least a part of which is a magnetic body made of a magnetic material, and a rotor fitted and fixed to the shaft;
It has a cylindrical shape extending in the axial direction with annular flanges formed on both edges, and an annular projecting portion projecting in a direction perpendicular to the surface of the flange is formed on the flange opposite to the input rotating body. A formed coil bobbin ;
A coil formed by winding an electric wire around the coil bobbin;
A shell that is loosely fitted to the rotor of the shaft on the opposite side of the input rotator, and encloses the coil bobbin on which the coil is formed;
The shell connects the outer cylinder covering the outer peripheral surface of the coil bobbin, the inner cylinder covering the inner peripheral surface of the protruding portion of the coil bobbin, the one end surface of the outer cylinder and the one end surface of the inner cylinder. And having a bottom plate covering a side surface of the protruding portion of the coil bobbin,
With protrusions protruding toward the shaft to the inner circumferential surface of the projecting portion of the coil bobbin is formed, notches in the inner cylindrical body of the shell opposite to the magnetic portion before Symbol shaft is formed, The protrusion protrudes from the notch ,
The rotor has a disk-shaped bottom plate, and a cylindrical tube continuously provided on the outer peripheral edge of the bottom plate,
An electromagnetic clutch characterized in that the cylindrical body of the rotor is positioned on the outer peripheral side of the coil bobbin so as to face the outer cylindrical body of the shell in the radial direction .   The electromagnetic clutch according to claim 1, wherein a plurality of the protrusions and the notches are formed at equal intervals along a circumferential direction of the shaft. The total length of the protrusions formed on the coil bobbin along the circumferential direction of the shaft, and the circle of the shaft in a portion where the notch is not formed on the surface of the shell facing the magnetic body portion The ratio of the total length along the circumferential direction is 1: 1 to 2, and the electromagnetic clutch according to claim 1 or 2.

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