JP3996607B2 - Power transmission device and method of assembling the same - Google Patents

Description

  The present invention relates to a power transmission device that transmits power by electromagnetic induction and an assembly method thereof.

  Patent Document 1 discloses a rotary joint for power transmission as a power transmission device that transmits power by electromagnetic induction. The power transmission rotary joint includes a rotating side core unit fixed to a rotating body including a rotating shaft, and a stationary side core unit fixed to a stationary body stationary with respect to the rotating body.

  Both core units each have a core part and an electromagnetic coil. The core part of both core units comprises a core body. The core portions of both core units are arranged to face each other so as to form an annular vacancy between these core portions. The annular vacant chamber is accommodated so that the electromagnetic coils of both core units are opposed to each other. The electromagnetic coils of both core units can transmit electric power to each other by electromagnetic induction. The core portions of both core units enhance the magnetic flux concentration effect and increase the power transmission efficiency.

JP 2002-25837 A

  When a core part having a cylindrical peripheral wall part and an inward flange part projecting radially inward from both axial ends of the peripheral wall part is used as the core part, an annular electromagnetic coil is attached to the core part. It is difficult to provide. Patent Document 1 does not disclose a technique for providing an electromagnetic coil in the core portion as described above.

  The objective of this invention is providing the electric power transmission apparatus which can improve the workability | operativity in an assembly, and its assembly method.

The present invention includes a first and a second electromagnetic coil that are provided in an annular shape so as to surround the shaft member, and that are capable of transmitting electric power to each other by electromagnetic induction, and are provided in an annular shape so as to surround the shaft member. A power transmission device including a core body that forms a passage for magnetic flux generated by current flowing through the first and second electromagnetic coils,
The core body is
A first peripheral core portion having a cylindrical peripheral wall portion and an outward flange portion projecting radially outward from both axial end portions of the peripheral wall portion;
A second electromagnetic coil is provided on the first core portion so as to face the outer side in the radial direction, and has a cylindrical peripheral wall portion and an inward flange portion projecting radially inward from both axial ends of the peripheral wall portion. Including a second core portion into which
The first and second core portions are constituted by substantially C-shaped core pieces arranged side by side in a circumferential direction,
The second core part is provided so as to be divided into a plurality of core parts composed of a plurality of core pieces in the circumferential direction, and is held by the holding means in a state where each core part is arranged in an annular shape,
The holding means is a power transmission device having a holder that can be divided into a plurality of holder portions in the circumferential direction, and each core portion is fixed to each holder portion .

  According to the present invention, the first and second electromagnetic coils are respectively provided in an annular shape so as to surround the shaft member. The first and second electromagnetic coils transmit power to each other by electromagnetic induction. The core body is provided in an annular shape so as to surround the shaft member, and forms a passage for magnetic flux generated by the current flowing through the first and second electromagnetic coils. This prevents magnetic flux leakage and improves power transmission efficiency.

  The core body has first and second core portions. The first core portion has a peripheral wall portion and an outward flange portion. The second core part has a peripheral wall part and an inward flange part. The second core portion is provided to face the first core portion from the outside in the radial direction. The first electromagnetic coil is fitted into the first core part, and the second electromagnetic coil is fitted into the second core part.

Therefore, the first and second core portions can cover the first and second electromagnetic coils in common, and the air gap between the first core portion and the second core portion can be made as small as possible. it can. As a result, the leakage magnetic flux generated by the current flowing through the first and second electromagnetic coils can be suppressed as much as possible.
The first and second core portions are configured by arranging substantially C-shaped core pieces in a circumferential direction with their side faces butted. Therefore, the first and second core portions having a large inner diameter can be realized by using a small core piece.

A 2nd core part is provided so that it can divide | segment into the several core part which consists of a several core piece regarding the circumferential direction. Such a 2nd core part is hold | maintained by a holding means in the state by which each core part was arrange | positioned at annular | circular shape. The holding means has a holder. The holder is provided so as to be divided into a plurality of holder portions in the circumferential direction. Each core part is fixed to each holder part. Therefore, the second electromagnetic coil is prepared in advance, first, each core portion composed of a plurality of core pieces is fixed to each holder portion, and then the second electromagnetic coil is covered from the outside in the radial direction . By assembling each core portion , the second electromagnetic coil can be fitted into the second core portion. In this way, workability in assembly can be improved.

The present invention is also a method of assembling the power transmission device for assembling the power transmission device,
While forming the 1st electromagnetic coil which encloses the surrounding wall part of this 1st core part in the 1st core part,
Each core portion comprising a plurality of core pieces respectively fixed to the holders portion, so as to cover the second electromagnetic coil from radially outward, by the assembly Rukoto each core portion, the second electromagnetic coil second core part Fit into
Fit the first core part into which the first electromagnetic coil fits into the second core part into which the second electromagnetic coil fits so that the second core part faces the first core part from the outside in the radial direction. A method for assembling the power transmission device.

According to the present invention, the first electromagnetic coil is formed in the first core portion . The respective secure each core portion comprising a plurality of core pieces each holder part, so as to cover the second electromagnetic coil from radially outward, by the assembly Rukoto each core portion, the second electromagnetic coil second core Fit into the part. Then, the first core part into which the first electromagnetic coil is fitted into the second core part into which the second electromagnetic coil is fitted is fitted so that the second core part faces the first core part from the outside in the radial direction. Include.

In the present invention, the second electromagnetic coil is prepared in advance, each core part composed of a plurality of core pieces is fixed to each holder part, and the second electromagnetic coil is covered from the outside in the radial direction , By assembling each core portion , the second electromagnetic coil can be fitted into the second core portion. In this way, workability in assembly can be improved.

According to this invention, the 2nd core part is provided so that it can divide | segment into the several core part which consists of a several core piece regarding the circumferential direction. Such a 2nd core part is hold | maintained by a holding means in the state by which each core part was arrange | positioned at annular | circular shape. The holding means has a holder. The holder is provided so as to be divided into a plurality of holder portions in the circumferential direction. Each core part is fixed to each holder part. Therefore, the second electromagnetic coil is prepared in advance, first, each core portion composed of a plurality of core pieces is fixed to each holder portion, and then the second electromagnetic coil is covered from the outside in the radial direction . By assembling each core portion , the second electromagnetic coil can be fitted into the second core portion. In this way, workability in assembly can be improved.

Further, according to the present invention, each core portion composed of a plurality of core pieces is fixed to each holder portion, and each core portion is assembled so as to cover the second electromagnetic coil from outside in the radial direction. The coil is fitted into the second core part. Therefore , workability in assembly can be improved.

  FIG. 1 is a cross-sectional view showing a power transmission device 2 according to an embodiment of the present invention with a part cut away. The power transmission device 2 is used as a wrist part of an articulated robot, for example. A tip tool is attached to the power transmission device 2. Electric power is supplied to the tip tool via the power transmission device 2.

  The power transmission device 2 includes a first structure 4 having a shaft member 3 and a second structure 5 provided so as to be angularly displaceable about the axis L1 of the shaft member 3 with respect to the first structure 4. Hereinafter, the “axis of the shaft member 3” may be simply referred to as “axis”. The shaft member 3 is cylindrical and has an outer diameter of, for example, about 120 mm. The first structural body 4 includes a first electromagnetic coil 6 and a first core portion 7. The second structural body 5 has a second electromagnetic coil 8 and a second core portion 9.

  The first and second electromagnetic coils 6 and 8 are provided in an annular shape so as to surround the shaft member 3. The inner diameter of the second electromagnetic coil 8 is larger than the outer diameter of the first electromagnetic coil 6. The first and second electromagnetic coils 6 and 8 are coaxial with the shaft member 3. The first and second electromagnetic coils 6 and 8 have the same position in the axial direction A. In other words, the second electromagnetic coil 8 is provided to face the first electromagnetic coil 6 from the outside in the radial direction. The first and second electromagnetic coils 6 and 8 can transmit electric power to each other by electromagnetic induction.

  FIG. 2 is a perspective view showing the core body 1. The core body 1 is configured by the first core portion 7 of the first configuration body 4 and the second core portion 9 of the second configuration body 5. The core body 1 is made of an electromagnetic steel plate. The core body 1 surrounds the shaft member 3 and is provided in an annular shape. The core body 1 forms a passage for magnetic flux generated by the current flowing through the first and second electromagnetic coils 6 and 8.

  The first and second core portions 7 and 9 are provided in an annular shape so as to surround the shaft member 3. The inner diameter of the second core part 9 is larger than the outer diameter of the first core part 7. The first and second core portions 7 and 9 are coaxial with the shaft member 3. The first and second core portions 7 and 9 have the same position in the axial direction A. In other words, the second core portion 9 is provided to face the first core portion 7 from the outside in the radial direction.

  FIG. 3 is a perspective view showing the first core portion 7. The first core portion 7 includes a cylindrical peripheral wall portion 11 and a pair of outward flange portions 12 a and 12 b that protrude radially outward from both end portions 11 a and 11 b in the axial direction A of the peripheral wall portion 11. The peripheral wall portion 11 and the pair of outward flange portions 12a and 12b form a recess 13 that retracts radially inward. The first electromagnetic coil 6 is fitted into the recess 13. The outer peripheral surfaces 14a and 14b of the pair of outward flange portions 12a and 12b are processed along a cylindrical surface coaxial with the shaft member 3.

  In the peripheral wall portion 11, a wire extraction hole 15 of the first electromagnetic coil 6 is formed. The extraction hole 15 penetrates the vicinity of the axial direction A one end portion 11a of the peripheral wall portion 11 in the radial direction. The electric wire of the first electromagnetic coil 6 is taken out to the radially inner side of the first core portion 7 through the take-out hole 15.

  The extraction hole may be formed in any one of the pair of outward flange portions 12a and 12b. In this case, the extraction hole penetrates one of the pair of outward flange portions 12a and 12b in the axial direction A. The electric wire of the 1st electromagnetic coil 6 is taken out to any one of the axial direction A one side and the other side of the 1st core part 7 via this extraction hole.

  In addition, an extraction groove may be formed in any one of the pair of outward flange portions 12a and 12b instead of the extraction hole. In this case, the extraction groove is formed along the axial direction A on one of the outer peripheral surfaces 14a and 14b of the pair of outward flange portions 12a and 12b. The electric wire of the 1st electromagnetic coil 6 is taken out to either one of the axial direction A one side and the other side of the 1st core part 7 via this extraction groove | channel.

  FIG. 4 is a perspective view showing the core piece 16 of the first core portion 7. The first core portion 7 is configured by arranging substantially C-shaped core pieces 16 in the circumferential direction B around the axis L1. In the present embodiment, the first core portion 7 is configured by arranging 18 core pieces 16 in the circumferential direction B. The core piece 16 includes a base portion 17 and a pair of projecting portions 18a and 18b.

  The base 17 is plate-shaped. The base 17 is a quadrangle when viewed from one side in the thickness direction C1, for example, a rectangle or a square. In other words, when viewed from one side in the thickness direction C1, the edge of the base portion 17 has two pairs of opposite sides parallel to each other, and the first pair of opposite directions C2 that is the direction in which the opposite side of one set extends and the other set. The second opposite side direction C3, which is the direction in which the opposite side extends, is perpendicular to each other. The first and second opposite side directions C2 and C3 are perpendicular to the thickness direction C1.

  One of the pair of protruding portions 18a and 18b protrudes from the first opposite side direction C2 one end portion 17a of the base portion 17 in the thickness direction C1, and the other protrudes from the first opposite side direction C2 other end portion 17b of the base portion 17 in the thickness direction. C1 protrudes to one side.

  In the present embodiment, the base portion 17 is rectangular when viewed from one side in the thickness direction C1. One of the pair of protrusions 18a and 18b protrudes from one end in the longitudinal direction, which is the first opposite side direction C2 one end 17a of the base 17, to one thickness direction C1, and the other is the first opposite side C2 of the base 17, etc. It protrudes in the thickness direction C1 from the other end in the longitudinal direction, which is the end 17b.

  FIG. 5 is a plan view showing the core piece 16 of the first core portion 7. FIG. 5 shows the core piece 16 viewed from one side in the first opposite side direction C2. The shape of the core piece 16 when viewed from one side in the first opposite direction C2 is the same as the shape when viewed from the other side of the first opposite direction C2. The description about is omitted. The core piece 16 is formed according to the shaft member 3.

  When viewed from one side in the first opposite side direction C2, the core piece 16 has a substantially trapezoidal shape. In the trapezoid, the shorter side of the opposite sides parallel to each other is referred to as the short side 19a, and the longer side is referred to as the long side 19b. The two sides inclined with respect to the opposite side are referred to as a pair of oblique sides 20a and 20b. When viewed from one side in the first opposite side direction C2, the edge of the core piece 16 is constituted by a short side 19a, a pair of oblique sides 20a and 20b, and an arc 19c.

  As the pair of hypotenuses 20a and 20b proceeds in one thickness direction C1, the distance in the second opposite side direction C3 increases. An angle θ11 formed by one hypotenuse 20a and the thickness direction C1 and an angle θ12 formed by the other hypotenuse 20b and the thickness direction C1 are the same. Each of these angles θ11 and θ12 is selected according to the number of core pieces 16 constituting the first core portion 7, and is selected to be 10 ° in the present embodiment.

  The arc 19c is an arc inscribed in the long side 19b. An angle θ13 formed by the tangent 111 of the arc 19c at the intersection P11 between the one hypotenuse 20a and the arc 19c and the one hypotenuse 20a is 90 °. The angle θ14 formed by the tangent 112 of the arc 19c at the intersection P12 between the other hypotenuse 20b and the arc 19c and the other hypotenuse 20b is 90 °.

  Such core pieces 16 are arranged in the circumferential direction B in a state in which the oblique sides 20a and 20b of each other are abutted. At this time, the first opposite direction C2 is the same as the axial direction A, and the second opposite direction C3 is the same as the circumferential direction B. The base portion 17 of each core piece 16 constitutes the peripheral wall portion 11 of the first core portion 7. A pair of outward flange portions 12 a and 12 b of the first core portion 7 is configured by the pair of projecting portions 18 a and 18 b of each core piece 16.

  FIG. 6 is a perspective view showing the second core portion 9. The second core portion 9 includes a cylindrical peripheral wall portion 21 and a pair of inward flange portions 22 a and 22 b that protrude radially inward from both end portions 21 a and 21 b in the axial direction A of the peripheral wall portion 21. The peripheral wall portion 21 and the pair of inward flange portions 22a and 22b form a recess 23 that retreats radially outward. The second electromagnetic coil 8 is fitted into the recess 23. The inner peripheral surfaces 24 a and 24 b of the pair of inward flange portions 22 a and 22 b are processed so as to follow a cylindrical surface coaxial with the shaft member 3.

  In the peripheral wall portion 21, a wire extraction hole 25 of the second electromagnetic coil 8 is formed. The take-out hole 25 penetrates the vicinity of the other end portion 21b in the axial direction A of the peripheral wall portion 21 in the radial direction. The electric wire of the second electromagnetic coil 8 is taken out to the radially outer side of the second core portion 9 through the take-out hole 25.

  The extraction hole may be formed in any one of the pair of inward flange portions 22a and 22b. In this case, the extraction hole penetrates one of the pair of inward flange portions 22a and 22b in the axial direction A. The electric wire of the 2nd electromagnetic coil 8 is taken out to either one of the axial direction A one side and the other side of the 2nd core part 9 via this extraction hole.

  Further, an extraction groove may be formed in any one of the pair of inward flange portions 22a and 22b in place of the extraction hole. In this case, the take-out groove is formed along the axial direction A on each inner peripheral surface 24a, 24b of the pair of inward flange portions 22a, 22b. The electric wire of the 2nd electromagnetic coil 8 is taken out to either one of the axial direction A one side and the other side of the 2nd core part 9 via this extraction groove | channel.

  FIG. 7 is a perspective view showing the core piece 26 of the second core portion 9. The second core portion 9 is configured by arranging substantially C-shaped core pieces 26 in the circumferential direction B around the axis L1. In the present embodiment, the second core portion 9 is configured by arranging 18 core pieces 26 in the circumferential direction B. The core piece 26 includes a base portion 27 and a pair of projecting portions 28a and 28b.

  The base 27 is plate-shaped. The base 27 is a quadrangle when viewed from one side in the thickness direction D1, for example, a rectangle or a square. In other words, when viewed from one side in the thickness direction D1, the edge of the base 27 has two pairs of opposite sides parallel to each other, and the first side direction D2 that is the direction in which one side of the pair extends and the other side The second opposite side direction D3, which is the direction in which the opposite side extends, is perpendicular to each other. The first and second opposite side directions D2 and D3 are perpendicular to the thickness direction D1.

  One of the pair of protrusions 28a and 28b protrudes from the first opposite side direction D2 one end 27a of the base 27 in the thickness direction D1, and the other protrudes from the first opposite side D2 other end 27b of the base 27 in the thickness direction. D1 protrudes to one side.

  In the present embodiment, the base 27 is rectangular when viewed from one side in the thickness direction D1. One of the pair of protrusions 28a and 28b protrudes from one end in the longitudinal direction which is the first opposite side direction D2 one end 27a of the base 27 in the thickness direction D1, and the other is the first opposite side direction D2 of the base 27 and the like. It protrudes in the thickness direction D1 from the other end in the longitudinal direction, which is the end 27b.

  FIG. 8 is a plan view showing the core piece 26 of the second core portion 9. FIG. 8 shows the core piece 26 viewed from one side in the first opposite side direction D2. The shape of the core piece 26 when viewed from one side in the first opposite direction D2 is the same as the shape when viewed from the other side of the first opposite direction D2, and therefore the shape when viewed from the other side of the first opposite direction D2. The description about is omitted. The core piece 26 is formed according to the shaft member 3.

  When viewed from one side of the first opposite side direction D2, the core piece 26 has a substantially trapezoidal shape. In the trapezoidal shape, of the opposite sides parallel to each other, the shorter side is called the short side 29a, and the longer side is called the long side 29b. The two sides inclined with respect to the opposite side are referred to as a pair of oblique sides 30a and 30b. When viewed from one side in the first opposite side direction D2, the edge of the core piece 26 is constituted by an arc 29c, a pair of oblique sides 30a and 30b, and a long side 29b.

  As the pair of hypotenuses 30a and 30b proceeds in one thickness direction D1, the distance in the second opposite side direction D3 decreases. The angle θ21 formed by one hypotenuse 30a and the thickness direction D1 is the same as the angle θ22 formed by the other hypotenuse 30b and the thickness direction D1. These angles θ21 and θ22 are selected according to the number of core pieces 26 constituting the second core portion 9, and are selected to be 10 ° in the present embodiment.

  The arc 29c is an arc passing through the intersection P21 between one oblique side 30a and the short side 29a and the intersection P22 between the other oblique side 30b and the short side 29a. An angle θ23 formed by the tangent 121 of the arc 29c at the intersection P21 between the one hypotenuse 30a and the short side 29a and the one hypotenuse 30a is 90 °. The angle θ24 formed by the tangent 122 of the arc 29c at the intersection P22 between the other hypotenuse 30b and the short side 29a and the other hypotenuse 30b is 90 °.

  Such core pieces 26 are arranged in the circumferential direction B in a state where the oblique sides 30a and 30b of each other are abutted. At this time, the first opposite direction D2 is the same as the axial direction A, and the second opposite direction D3 is the same as the circumferential direction B. The base portion 27 of each core piece 26 constitutes the peripheral wall portion 21 of the second core portion 9. A pair of inward flange portions 22 a and 22 b of the second core portion 9 is configured by the pair of projecting portions 28 a and 28 b of each core piece 26.

  In the core piece 16 of the first core portion 7, the distance between the intersection P11 between the one oblique side 20a and the arc 19c and the intersection P12 between the other oblique side 20b and the arc 19c is defined as a first intersection distance W101. Further, in the core piece 26 of the second core portion 9, the distance between the intersection point P21 between the one oblique side 30a and the short side 29a and the intersection point P22 between the other oblique side 30b and the short side 29a is defined as a second intersection distance W102. . At this time, the distance W102 between the second intersections is larger than the distance W101 between the first intersections.

  FIG. 9 is a cross-sectional view of the core body 1 as seen by cutting along a plane including the axis L1. The outward flange portions 12a, 12b of the first core portion 7 and the inward flange portions 22a, 22b of the second core portion 9 are at the same position in the axial direction A. An annular space 31 is formed by the first core portion 7 and the second core portion 9. The first and second electromagnetic coils 6 and 8 are accommodated in the space 31. The first electromagnetic coil 6 is accommodated in the recess 13 of the first core portion 7 in the space 31. The second electromagnetic coil 8 is accommodated in the recess 23 of the second core portion 9 in the space 31.

  A gap W <b> 1 is formed between the outward flange portions 12 a and 12 b of the first core portion 7 and the inward flange portions 22 a and 22 b of the second core portion 9. As the gap W1 is smaller, the leakage magnetic flux can be suppressed. In the present embodiment, the gap W1 between the outward flange portions 12a, 12b of the first core portion 7 and the inward flange portions 22a, 22b of the second core portion 9 is about 0.1 to 0.2 mm. is there. The width W2a in the axial direction A of the outward flange portions 12a and 12b of the first core portion 7 and the width W2b in the axial direction A of the inward flange portions 22a and 22b of the second core portion 9 are the same.

  FIG. 10 is a perspective view showing the wound iron core 36. The wound iron core 36 is formed by winding a magnetic steel sheet into a cylindrical shape. The wound iron core 36 is formed as a magnetic steel plate, for example, by winding a silicon steel plate whose surface is electrically insulated into a cylindrical shape.

  The wound iron core 36 is formed by winding a magnetic steel sheet into, for example, a rectangular tube shape. The cross section perpendicular to the axis of the wound core 36 is rectangular or square. The wound core 36 is constituted by plate-like first to fourth plate-like portions 36a to 36d. The first and second plate-like portions 36a and 36b face each other in a parallel state. The third and fourth plate-like portions 36c and 36d face each other in a parallel state.

  In the present embodiment, the cross section perpendicular to the axis of the wound iron core 36 is rectangular. The interval W11 between the first and second plate-like portions 36a and 36b is larger than the interval W12 between the third and fourth plate-like portions 36c and 36d. Such a wound core 36 is cut to form the core piece 16 of the first core portion 7 and the core piece 26 of the second core portion 9.

  FIG. 11 is a plan view showing a part of the wound iron core 36 in order to explain an example of the manufacturing method of the first and second core portions 7 and 9. FIG. 11 shows the wound iron core 36 viewed from a direction perpendicular to the first plate-like portion 36a. The first and second core portions 7 and 9 are formed by cutting the wound core 36 along a plane that intersects the axis L2 of the wound core 36 and cutting along a plane parallel to the axis L2 of the wound core 36. .

  In an example of the manufacturing method of the first and second core portions 7 and 9, first, the wound iron core 36 is cut at a pair of cross axis cut surfaces 37 a and 37 b that are planes intersecting the axis L <b> 2 of the wound iron core 36. It cut | disconnects by the axis parallel cut surface 38 which is a plane parallel to the axis line L2 of the iron core 36. FIG. The pair of axis crossing cut surfaces 37a and 37b and the axis parallel cut surface 38 are perpendicular to the first plate-like portion 36a.

  The axis parallel cut surface 38 is disposed between the third and fourth plate-like portions 36c and 36d. In the present embodiment, the axial parallel cut surface 38 is disposed at the center between the third and fourth plate-like portions 36c and 36d. In other words, the axis parallel cut surface 38 includes the axis L <b> 2 of the wound core 36.

  The pair of cross-axis planes 37a and 37b are inclined with respect to the axis L2 of the wound iron core 36 so as to approach each other in the direction E from the third plate portion 36c toward the fourth plate portion 36d. An angle θ31 formed by one axis cross-cut surface 37a and the axis L2 of the wound core 36 is the same as an angle θ32 formed by the other axis cross-cut surface 37b and the axis L2 of the wound core 36. Each of these angles θ31 and θ32 is selected according to the number of core pieces 16 constituting the first core portion 7, and is selected to be 10 ° in the present embodiment.

  Between the pair of cross-axis planes 37a and 37b, the first core piece precursor 41 which is the precursor of the core piece 16 of the first core portion 7 and the precursor of the core piece 26 of the second core portion 9 are used. A second core piece precursor 42 is formed. The first core piece precursor 41 is a portion closer to the fourth plate-like portion 36d with respect to the axis parallel cut surface 38. The second core piece precursor 42 is a portion closer to the third plate-like portion 36 c with respect to the axial parallel cut surface 38.

  Next, a plurality of, in the present embodiment, 18 first core piece precursors 41 are arranged side by side in the circumferential direction and arranged in an annular shape to constitute the precursor of the first core portion 7. . The outer peripheral surface of the precursor of the first core portion 7 is processed into a cylindrical surface inscribed in the outer peripheral surface. Thus, the 1st core part 7 is manufactured.

  Also, in the present embodiment, a plurality of 18 second core piece precursors 42 are arranged in an annular shape by abutting the side surfaces and arranged in a ring shape to constitute the precursor of the second core portion 9. The inner peripheral surface of the precursor of the second core portion 9 is processed into a cylindrical surface that circumscribes the inner peripheral surface. In this way, the second core portion 9 is manufactured.

  FIG. 12 is a plan view showing a part of a wound iron core 36 for explaining another example of the manufacturing method of the first and second core portions 7 and 9. FIG. 12 shows the wound iron core 36 viewed from a direction perpendicular to the first plate-like portion 36a. In the first and second core portions 7 and 9, the wound core 36 is cut along a plane that intersects the axis L2 of the wound core 36 and is parallel to the axis L2 of the wound core 36, as in the above example. Formed by cutting.

  In another example of the manufacturing method of the first and second core portions 7 and 9, the wound iron core 36 is first cut at an axis parallel cut surface 71 that is a plane parallel to the axis L <b> 2 of the wound iron core 36. The axis parallel cut surface 71 is perpendicular to the first plate-like portion 36a. The axis parallel cut surface 71 is disposed between the third and fourth plate-like portions 36c and 36d. In the present embodiment, the axis parallel cut surface 71 is disposed at the center between the third and fourth plate-like portions 36c and 36d. In other words, the axis parallel cut surface 71 includes the axis L <b> 2 of the wound core 36.

  Next, a portion 72 near the fourth plate-like portion 36d with respect to the axis parallel cut surface 71 is cut by a pair of first axis cross cut surfaces 73a and 73b which are planes intersecting the axis L2 of the wound core 36. A first core piece precursor 74 that is a precursor of the core piece 16 of the first core portion 7 is formed between the pair of first axis crossing cut surfaces 73a and 73b.

  The pair of first axis crossing cut planes 73 a and 73 b is perpendicular to the first plate-like portion 36 a and intersects the axis L <b> 2 of the wound core 36. The pair of first axis crossing cut planes 73a and 73b are inclined with respect to the axis L2 of the wound iron core 36 so as to approach each other in the direction E from the third plate-like portion 36c toward the fourth plate-like portion 36d. .

  An angle θ41 formed by one first axis cross-cut surface 73a and the axis L2 of the wound core 36 is the same as an angle θ42 formed by the other first axis cross-cut surface 73b and the axis L2 of the wound core 36. . Each of these angles θ41, θ42 is selected according to the number of core pieces 16 constituting the first core portion 7, and is selected to be 10 ° in the present embodiment.

  Further, a portion 75 near the third plate-like portion 36c with respect to the axis parallel cut surface 71 is cut by a pair of second axis cross cut surfaces 76a and 76b which are planes intersecting the axis L2 of the wound core 36. A second core piece precursor 77 which is a precursor of the core piece 26 of the second core portion 9 is formed between the pair of second axis crossing cut planes 76a and 76b.

  The pair of second axis crossing cutting planes 76 a and 76 b is perpendicular to the first plate-like portion 36 a and intersects the axis L <b> 2 of the wound core 36. The pair of second axis crossing cut planes 76a and 76b are inclined with respect to the axis L2 of the wound iron core 36 so as to approach each other in the direction E from the third plate-like portion 36c toward the fourth plate-like portion 36d. .

  The angle θ51 formed by one second axis cross-cut surface 76a and the axis L2 of the wound core 36 is the same as the angle θ52 formed by the other second axis cross-cut surface 76b and the axis L2 of the wound core 36. . Each of these angles θ51 and θ52 is selected according to the number of core pieces 26 constituting the second core portion 9, and is selected to be 10 ° in the present embodiment.

  The distance between the straight line intersecting the axis parallel cut surface 71 and one first axis cross cut surface 73a and the straight line intersecting the axis parallel cut surface 71 and the other first axis cross cut surface 73b is defined as the distance between the first straight lines. The distance is W31. The distance between the straight line where the axis parallel cut surface 71 and one second axis cross cut surface 76a intersect and the distance between the straight line where the axis parallel cut surface 71 and the other second axis cross cut surface 76b intersect is defined as the second straight line. The distance is W32. At this time, the second straight line distance W32 is smaller than the first straight line distance W31.

  Next, a plurality of, in the present embodiment, 18 first core piece precursors 74 are arranged side by side in the circumferential direction and arranged in an annular shape to constitute the precursor of the first core portion 7. . The outer peripheral surface of the precursor of the first core portion 7 is processed into a cylindrical surface inscribed in the outer peripheral surface. Thus, the 1st core part 7 is manufactured.

  Further, in the present embodiment, a plurality of 18 second core piece precursors 77 are arranged in an annular shape with their side surfaces butted in the circumferential direction to constitute the precursor of the second core portion 9. The inner peripheral surface of the precursor of the second core portion 9 is processed into a cylindrical surface that circumscribes the inner peripheral surface. In this way, the second core portion 9 is manufactured.

  FIG. 13 is a projection view in which the first and second core piece precursors 74 and 77 shown in FIG. 12 are projected onto a plane parallel to the first plate-like portion 36 a of the wound core 36. When the first and second core piece precursors 74 and 77 shown in FIG. 12 are projected onto a plane parallel to the first plate-like portion 36a of the wound core 36, the first and second core pieces are projected on the parallel plane. The precursors 74 and 77 are each trapezoidal.

  The trapezoidal edges of the first core piece precursor 74 are constituted by opposite sides 81 and 82 that are parallel to each other and a pair of oblique sides 83 and 84 that are inclined with respect to the opposite sides 81 and 82. Of the opposite sides 81, 82, the shorter side is referred to as the short side 81, and the longer side is referred to as the long side 82.

  The trapezoidal edges of the second core piece precursor 77 are constituted by opposite sides 91 and 92 that are parallel to each other and a pair of oblique sides 93 and 94 that are inclined with respect to the opposite sides 91 and 92. Of the opposite sides 91 and 92, the shorter side is referred to as a short side 91, and the longer side is referred to as a long side 92.

  As described above, when the outer peripheral surface of the precursor of the first core portion 7 is processed into a cylindrical surface inscribed in the outer peripheral surface, the first core piece precursor 74 is formed with an arc 85 indicated by a virtual line. The arc 85 is an arc inscribed in the long side 82. The tangent line of the arc 85 at the intersection P 31 between the one oblique side 83 and the arc 85 is perpendicular to the one oblique side 83. The tangent line of the arc 85 at the intersection P 32 between the other hypotenuse 84 and the arc 85 is perpendicular to the other hypotenuse 84.

  Further, as described above, when the inner peripheral surface of the precursor of the second core portion 9 is processed into a cylindrical surface circumscribing the inner peripheral surface, an arc 95 indicated by an imaginary line is formed in the second core piece precursor 77. Is done. The arc 95 is an arc passing through the intersection P33 between one oblique side 93 and the short side 91 and the intersection P34 between the other oblique side 94 and the short side 91. The tangent line of the arc 95 at the intersection P33 between the one oblique side 93 and the arc 95 is perpendicular to the one oblique side 93. The tangent line of the arc 95 at the intersection P 34 between the other hypotenuse 94 and the arc 95 is perpendicular to the other hypotenuse 94.

  In another example of the manufacturing method of the first and second core portions 7 and 9, the length W42 of the short side 91 of the second core piece precursor 77 is the length of the long side 82 of the first core piece precursor 74. It is smaller than W41. Moreover, the length W42 of the short side 91 of the second core piece precursor 77 is greater than the length W43 of the string connecting the intersections P31 and P32 between the pair of oblique sides 83 and 84 and the arc 85 in the first core piece precursor 74. Is also big.

  FIG. 14 is a projection view in which the core piece 16 of the first core portion 7 and the core piece 26 of the second core portion 9 are projected onto a plane perpendicular to the axis L1. In another example of the manufacturing method of the first and second core portions 7 and 9, the length W42 of the short side 91 of the second core piece precursor 77 is the length of the first core piece precursor 74 as described above. The length of the side 82 is smaller than W41. Therefore, when the core pieces 16 and 26 are arranged so that the centers of the arcs 85 and 95 are the same, the interval W51 between the core pieces 16 and 26 is such that the core piece 26 of the second core portion 9 is the first. This is even smaller than in the case of the above example arranged at the position indicated by the virtual line 98 with respect to the core piece 16 of the core portion 7.

  In another example of the manufacturing method of the first and second core portions 7 and 9, the length W42 of the short side 91 of the second core piece precursor 77 is the same as that of the first core piece precursor 74 as described above. It is longer than the length W43 of the string connecting the intersections P31 and P32 between the pair of oblique sides 83 and 84 and the arc 85. Therefore, when each core piece 16 and 26 is arrange | positioned so that the center of each circular arc 85 and 95 may become the same, the malfunction that each core piece 16 and 26 contacts can be prevented.

  FIG. 15 is a plan view showing a part of the wound core 36 in order to explain still another example of the manufacturing method of the first and second core portions 7 and 9. FIG. 16 is a perspective view showing the precursor 43 of the core body 1. FIG. 15 shows the wound iron core 36 viewed from a direction perpendicular to the first plate-like portion 36a.

  In still another example of the manufacturing method of the first and second core portions 7 and 9, the wound core 36 is first cut at a pair of cross-axis cross-cut surfaces 131 a and 131 b that are planes that intersect the axis L <b> 2 of the wound core 36. . The pair of axis crossing cut surfaces 131 a and 131 b is perpendicular to the first plate-like portion 36 a and intersects the axis L <b> 2 of the wound core 36. The pair of cross-axis cross-cut surfaces 131a and 131b are inclined with respect to the axis L2 of the wound iron core 36 so as to approach each other in the direction E from the third plate-like portion 36c toward the fourth plate-like portion 36d.

  The angle θ61 formed by one axis cross-cut surface 131a and the axis L2 of the wound core 36 is the same as the angle θ62 formed by the other axis cross-cut surface 131b and the axis L2 of the wound core 36. Each of these angles θ61 and θ62 is selected according to the number of core pieces 16 constituting the first core portion 7, and is selected to be 10 ° in the present embodiment.

  Next, a plurality of portions 132 sandwiched between the pair of cross-axis planes 37a and 37b, 18 in the present embodiment, the oblique sides are butted and arranged in the circumferential direction, arranged in an annular shape, and the precursor of the core body 1 The body 43 is configured. The precursor 43 of the core body 1 is cut along a circle 44 shown in FIG. Thus, the 1st and 2nd core parts 7 and 9 are manufactured.

  FIG. 17 is a cross-sectional view showing the power transmission device 2. As described above, the power transmission device 2 includes the first structural body 4 including the shaft member 3 and the second structural body 5 provided to be angularly displaceable around the axis L1 of the shaft member 3 with respect to the first structural body 4. Including.

  The first structural body 4 includes a pair of protective members 51 a and 51 b in addition to the shaft member 3, the first electromagnetic coil 6 and the first core portion 7. The pair of protection members 51 a and 51 b are provided in an annular shape so as to surround the shaft member 3. The pair of protection members 51 a and 51 b are coaxial with the shaft member 3. One protective member 51 a contacts the first core portion 7 from one side in the axial direction A and is fixed to the first core portion 7. The other protection member 51 b comes into contact with the first core portion 7 from the other side in the axial direction A and is fixed to the first core portion 7. The pair of protective members 51a and 51b prevent friction between the first core portion 7 and a pair of locking members 52a and 52b in the second structural body 5 described later. Protected. The first core portion 7 and the pair of protective members 51 a and 51 b are fixed to the shaft member 3. An annular flange member 53 is fixed to the one end 3a in the axial direction A of the shaft member 3 by a bolt member.

  In addition to the 2nd electromagnetic coil 8, the 2nd core part 9, the 2nd structure 5 has the holder 54 holding the 2nd core part 9, and a pair of locking member 52a, 52b. The holder 54 includes a cylindrical peripheral wall portion 55 and an inward flange portion 56 that protrudes inward in the radial direction from the axial direction A one end portion 55 a of the peripheral wall portion 55. The peripheral wall portion 55 surrounds the second core portion 9. The inward flange portion 56 comes into contact with the second core portion 9 from the other side in the axial direction A of the second core portion 9 and is fixed to the second core portion 9.

  The pair of locking members 52 a and 52 b are provided in an annular shape so as to surround the shaft member 3. The pair of locking members 52 a and 52 b are coaxial with the shaft member 3. One locking member 52a comes into contact with the holder 54 from one side in the axial direction A and is fixed to the holder 54 with a bolt member. The one locking member 52a abuts against the one protective member 51a from one side in the axial direction A. The other locking member 52b contacts the holder 54 from the other side in the axial direction A, and is fixed to the holder 54 by a bolt member. The other locking member 52b comes into contact with the other protective member 51b from the other in the axial direction A.

  FIG. 18 is a perspective view showing a separated state of the second core portion 9. The 2nd core part 9 is provided in a several core part so that isolation | separation is possible regarding the circumferential direction. In the present embodiment, the second core portion 9 is provided so as to be separable into the two core portions 9a and 9b on both sides with respect to the plane including the axis L1. The holder 54 is provided so as to be separable into a plurality of holder portions 54a and 54b in the circumferential direction. In the present embodiment, the holder 54 is provided so as to be separable into two holder portions 54a and 54b on both sides with respect to a plane including the axis L1. The core portions 9a and 9b are fixed to the holder portions 54a and 54b, respectively.

  Each core part 9a, 9b and each holder part 54a, 54b are fixed by a pair of locking members 52a, 52b and a bolt member in a state of being arranged in an annular shape. The holder portions 54a and 54b and the pair of locking members 52a and 52b serve as holding means 59 for holding the core portions 9a and 9b of the second core portion 9 in an annularly arranged state.

  FIG. 19 is a flowchart for explaining an assembling method of the power transmission device 2. FIG. 20 is an exploded cross-sectional view of the power transmission device 2. In assembling the power transmission device 2, first, in step s 1, the first electromagnetic coil 6 is formed in the first core portion 7, and in step s 2, the second core portion 9 is divided into second electromagnetic coils. The second electromagnetic coil 8 is fitted into the second core portion 9 by assembling so as to cover 8 from the outside in the radial direction. Thereafter, in step s3, the first core portion 7 into which the first electromagnetic coil 6 is fitted into the second core portion 9 into which the second electromagnetic coil 8 is fitted, and the second core portion 9 into the first core portion 7 are fitted. Fit so that it faces from the outside in the radial direction.

  More specifically, when forming the first electromagnetic coil 6 in the first core portion 7, first, the shaft member 3 is provided with a pair of protective members 51 a and 51 b and the first core portion 7. Then, the first electromagnetic coil 6 is formed on the first core portion 7. In this way, the first structure 4 is configured.

  In fitting the second electromagnetic coil 8 into the second core portion 9, an annular second electromagnetic coil 8 is prepared in advance. And in the state which decomposed | disassembled each holder part 54a, 54b of the holder 54, each core part 9a, 9b of the 2nd core part 9 is provided in these each holder part 54a, 54b. Then, the second core portion 9 is divided and provided so as to cover the second electromagnetic coil 8 from the outside in the radial direction, and the second electromagnetic coil 8 is fitted into the second core portion 9. Then, each holder part 54a, 54b and the other locking member 52b are fixed with a bolt member. In this way, a part 60 of the second structure 5 is configured.

  In fitting the first core portion 7 into the second core portion 9, the first structural body 4 is moved in the axial direction A from the one axial direction A side of the part 60 of the second structural body 5. The first core portion 7 into which the first electromagnetic coil 6 is fitted into the second core portion 9 into which the second electromagnetic coil 8 is fitted, and the second core portion 9 from the radially outer side to the first core portion 7. Fit so that they face each other.

  After fitting the first core portion 7 into the second core portion 9 in this way, one locking member 52 a is fixed to the holder 54 with a bolt member, and the flange member 53 is further fixed to the shaft member 3. In this way, the power transmission device 2 can be assembled.

  According to the present embodiment as described above, since the core body 1 is made of an electromagnetic steel plate, it has higher toughness than a ferrite core obtained by sintering a magnetic material powder, and breakage such as chipping and cracking can be prevented. . Such a core body 1 can be suitably used regardless of the outer diameter of the shaft member.

  Moreover, since the core body 1 consists of an electromagnetic steel plate, a saturation magnetic flux density is high compared with a ferrite core. In such a core body 1, in order to prevent saturation of magnetic flux, it is not necessary to convert the power to be transmitted into high-frequency power as in the case of a ferrite core. For example, in the case of a ferrite core, power of several tens of kHz is used, but in the present embodiment, power of about 1 kHz is used. Therefore, it is possible to prevent the generation of high frequency noise due to power conversion. Thereby, for example, when a signal is transmitted together with electric power, a noise prevention measure becomes unnecessary, and the manufacturing cost can be reduced.

  Moreover, according to this Embodiment, the several core pieces 16 and 26 which consist of electromagnetic steel plates are assembled, and the core body 1 is comprised by this. Therefore, even the core body 1 having a shape that is difficult to be integrally molded can be realized by combining a plurality of core pieces 16 and 26.

  Moreover, according to this Embodiment, the 1st and 2nd core parts 7 and 9 can cover the 1st and 2nd electromagnetic coils 6 and 8 in common, and also the 1st core part 7 and the 2nd core part 9 can be made as small as possible. Thereby, the leakage magnetic flux can be suppressed as much as possible.

  Such first and second core portions 7 and 9 are configured by arranging substantially C-shaped core pieces 16 and 26 in the circumferential direction. Accordingly, the first and second core portions 7 and 9 having a large inner diameter can be realized using the small core pieces 16 and 17.

  Moreover, since the 1st and 2nd core parts 7 and 9 are comprised by arranging the substantially C-shaped core pieces 16 and 26 in the circumferential direction, the internal peripheral surface of the 1st core part 7 is a polygonal cylinder shape. The outer peripheral surface of the second core portion 9 has a polygonal cylindrical shape. Therefore, the slip between the 1st core part 7 and the shaft member 3 can be prevented, and the slip between the 2nd core part 9 and the holder 54 can be prevented.

  According to the present embodiment, the wound iron core formed by winding the electromagnetic steel sheet into a cylindrical shape is cut along a plane intersecting the axis L2, and is cut along a plane parallel to the axis L2. Substantially C-shaped core pieces 16 and 26 are formed. Since the C-shaped core pieces 16 and 26 are arranged in the circumferential direction B to form the first and second core portions 7 and 9, they are generated by the current flowing through the first and second electromagnetic coils 6 and 8. The passage path of the magnetic flux can be formed along the winding direction of the electromagnetic steel sheet, thereby suppressing the leakage magnetic flux. Further, it is possible to prevent a problem that eddy current flows through the core pieces 16 and 26.

  The first electromagnetic coil 6 is fitted into the first core part 7, and the second electromagnetic coil 8 is fitted into the second core part 9. Therefore, the first and second core coils 7 and 9 can cover the first and second electromagnetic coils 6 and 8 in common, and the air gap between the first core module 7 and the second core module 9 can be reduced. It can be made as small as possible. As a result, the leakage magnetic flux generated by the current flowing through the first and second electromagnetic coils 6 and 8 can be suppressed as much as possible.

  The second core portion 9 is provided so as to be divided into two core portions 9a and 9b in the circumferential direction B. Accordingly, the second electromagnetic coil 8 is prepared in advance, and the second core coil 9 is divided and the second electromagnetic coil 8 is assembled by covering the second electromagnetic coil 8 from outside in the radial direction. Can be fitted into the second core portion 9. In this way, workability in assembly can be improved.

  Further, according to the present embodiment, the holding means 59 can hold the core portions 9a and 9b of the second core portion 9 and maintain the core portions 9a and 9b in an annular shape. .

  The above-described embodiment is merely an example of the present invention, and the configuration can be changed within the scope of the present invention. For example, the outer peripheral surfaces 14a and 14b of the pair of outward flange portions 12a and 12b of the first core portion 7 are not necessarily processed into a cylindrical surface, and may be polygonal cylindrical surfaces. Further, the inner peripheral surfaces 24a and 24b of the pair of inward flange portions 22a and 22b of the second core portion 9 are not necessarily processed into a cylindrical surface, and may be polygonal cylindrical surfaces. In the present invention, the outer peripheral surfaces 14a and 14b of the pair of outward flange portions 12a and 12b of the first core portion 7 and the inner peripheral surfaces 24a and 24b of the pair of inward flange portions 22a and 22b of the second core portion 9 are provided. If it does not contact with.

  The number of substantially C-shaped core pieces 16 constituting the first core portion 7 is not limited to 18 and may be three or more. Further, the number of C-shaped core pieces 26 constituting the second core portion 9 is not limited to 18 and may be 3 or more. The number of core pieces 16 constituting the first core portion 7 and the number of core pieces 26 constituting the second core portion 9 are not necessarily the same and may be different.

  The core body 1 may be configured by assembling core pieces of other shapes instead of the substantially C-shaped core pieces 16 and 26. For example, the first core portion 7 is configured by assembling a cylindrical first core piece that surrounds the shaft member 3 and a pair of annular second core pieces that surround the shaft member 3. Also good. In this case, the first core piece becomes the peripheral wall portion 11 of the first core portion 7, and the pair of second core pieces becomes the pair of outward flange portions 12 a and 12 b of the first core portion 7. The first core piece is formed by winding a magnetic steel sheet in a cylindrical shape. The second core piece is formed by laminating annular electromagnetic steel plates in the axial direction.

  The present invention is not limited to the configuration in which the second structural body 5 can be angularly displaced about the axis L1 with respect to the first structural body 4 having the shaft member 3, but the second structural body with respect to the first structural body 4. The present invention can also be applied to a configuration in which 5 is removable.

It is sectional drawing which notches one part and shows the electric power transmission apparatus 2 which is one Embodiment of this invention. 1 is a perspective view showing a core body 1. FIG. FIG. 5 is a perspective view showing a first core part 7. 4 is a perspective view showing a core piece 16 of the first core portion 7. FIG. 3 is a plan view showing a core piece 16 of the first core portion 7. FIG. FIG. 6 is a perspective view showing a second core part 9. FIG. 6 is a perspective view showing a core piece 26 of a second core portion 9. FIG. 6 is a plan view showing a core piece 26 of a second core portion 9. It is sectional drawing which cut | disconnected and saw the core body 1 by the plane containing the axis line L1. 3 is a perspective view showing a wound iron core 36. FIG. FIG. 4 is a plan view showing a part of a wound core 36 for explaining an example of a method for manufacturing the first and second core portions 7 and 9. FIG. 6 is a plan view showing a part of a wound core 36 for explaining another example of the method for manufacturing the first and second core portions 7 and 9. FIG. 13 is a projection view in which the first and second core piece precursors 74 and 77 shown in FIG. 12 are projected onto a plane parallel to the first plate portion 36 a of the wound core 36. FIG. 6 is a projection view in which the core piece 16 of the first core portion 7 and the core piece 26 of the second core portion 9 are projected onto a plane perpendicular to the axis L1. FIG. 6 is a plan view showing a part of a wound iron core 36 for explaining still another example of the method for manufacturing the first and second core portions 7 and 9. 3 is a perspective view showing a precursor 43 of a core body 1. FIG. 3 is a cross-sectional view showing a power transmission device 2. FIG. FIG. 6 is a perspective view showing a separated state of the second core portion 9. 6 is a flowchart for explaining an assembly method of the power transmission device 2; It is sectional drawing which decomposes | disassembles and shows the electric power transmission apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Core body 2 Electric power transmission apparatus 3 Shaft member 4 1st structure 5 2nd structure 6 1st electromagnetic coil 7 1st core part 8 2nd electromagnetic coil 9 2nd core part 11 Peripheral wall part 12a of 1st core part 7 12b A pair of outward flange portions of the first core portion 16 A core piece of the first core portion 21 A peripheral wall portion 22a of the second core portion 7 A 22b A pair of inward flange portions of the second core portion 26 Second The core piece of the core portion 9 36 The wound core 37a, 37b A pair of cross-axis cut surfaces 38 Axis parallel cut surfaces 59 Holding means

Claims (2)

The first and second electromagnetic coils are provided in an annular shape so as to surround the shaft member and can transmit electric power to each other by electromagnetic induction, and are provided in an annular shape so as to surround the shaft member. A power transmission device including a core body that forms a passage path of magnetic flux generated by a current flowing through an electromagnetic coil,
The core body is
A first peripheral core portion having a cylindrical peripheral wall portion and an outward flange portion projecting radially outward from both axial end portions of the peripheral wall portion;
A second electromagnetic coil is provided on the first core portion so as to face the outer side in the radial direction, and has a cylindrical peripheral wall portion and an inward flange portion projecting radially inward from both axial ends of the peripheral wall portion. Including a second core portion into which
The first and second core portions are constituted by substantially C-shaped core pieces arranged side by side in a circumferential direction,
The second core part is provided so as to be divided into a plurality of core parts composed of a plurality of core pieces in the circumferential direction, and is held by the holding means in a state where each core part is arranged in an annular shape,
The holding means includes a holder that can be divided into a plurality of holder portions in the circumferential direction, and each core portion is fixed to each holder portion . A method of assembling a power transmission device for assembling the power transmission device according to claim 1,
While forming the 1st electromagnetic coil which encloses the surrounding wall part of this 1st core part in the 1st core part,
Each core part composed of a plurality of core pieces is fixed to each holder part, and the second electromagnetic coil is attached to the second core part by assembling each core part so as to cover the second electromagnetic coil from outside in the radial direction. Fitting,
Fit the first core part into which the first electromagnetic coil fits into the second core part into which the second electromagnetic coil fits so that the second core part faces the first core part from the outside in the radial direction. assembling method you wherein power transmitting device.

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