Rotation detector

Abstract

To provide a smaller rotation detector. [Solution] The rotation detector is a rotation detector mounted on a bearing having an inner ring and an outer ring, comprising a rotor mounted on the inner ring, a stator facing the rotor, an output coil provided on the rotor, and a detection coil provided on the stator and facing the output coil. The rotor is integrally formed from the same material as the inner ring and has a flange extending radially outward from the X1 side portion of the inner ring. The output coil is provided on the X1 side surface of the flange. The stator has a cover member located on the X1 side relative to the rotor. The detection coil is provided on the X2 side surface of the cover member.

Description

Technical Field

[0001] This disclosure relates to a rotation detector.

Background Art

[0002] A rotation detector for detecting the rotation angle of a detected object such as a motor is known (see, for example, Patent Document 1). The rotation detector of Patent Document 1 is a resolver. Specifically, the resolver device of Patent Document 1 includes a shaft, a bearing, a case, a rotor, and a stator. The shaft extends in the axial direction of the central axis. The bearing is attached to the outer periphery of the shaft. That is, the bearing has an inner ring fixed to the outer peripheral surface of the shaft, an outer ring provided on the outer peripheral side of the inner ring, and rolling elements. The case is attached to the outer periphery of the outer ring. The rotor is attached to the outer periphery of the shaft at a position axially spaced from the bearing. The stator is attached to the inner peripheral surface of the case. The stator is located on the outer peripheral side of the rotor and faces the rotor in the radial direction.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the rotation detector according to Patent Document 1, the rotor, the stator, and the bearing are separate bodies, and the rotor, the stator, and the bearing are arranged axially spaced apart. Therefore, the rotation detector of Patent Document 1 may be enlarged.

[0005] This disclosure has been made in view of the above, and an object thereof is to provide a more compact rotation detector.

Means for Solving the Problems

[0006] To achieve the above objective, a rotation detector according to one aspect of the present disclosure is a rotation detector mounted on a bearing having an inner ring and an outer ring, comprising: a rotor mounted on the inner ring; a stator facing the rotor; an output coil provided on the rotor; and a detection coil provided on the stator and facing the output coil.

[0007] As mentioned above, in the rotation detector described in Patent Document 1, the rotor, stator, and bearings are separate components. Furthermore, the rotor and stator and the bearings are spaced apart in the axial direction. Therefore, the rotation detector described in Patent Document 1 may be large in size.

[0008] In contrast, the rotation detector according to this disclosure is integrated with the bearing. More specifically, in the rotation detector, the rotor is attached to the inner ring, and the stator faces the rotor. Therefore, this disclosure can provide a rotation detector that is smaller than the rotation detector of Patent Document 1.

[0009] In another embodiment of the rotation detector described above, the rotor is integrally formed from the same material as the inner ring and has a flange extending radially outward from one axial side of the inner ring, with the output coil provided on one axial side of the flange, and the stator has a cover member located on one axial side with respect to the rotor, with the detection coil provided on the other axial side of the cover member.

[0010] The flange of the rotor is integrally formed from the same material as the inner ring, and the stator is mounted on a cover member. An output coil is provided on the flange, and a detection coil is provided on the cover member. By integrating the rotor and stator with the bearing in this way, a smaller rotation sensor can be provided. In particular, since the flange is integrally formed from the same material as the inner ring, the mounting rigidity of the flange to the inner ring is increased, and the vibration of the flange when the rotor rotates is suppressed, so that the air gap between the flange and the cover member can be set to a smaller size.

[0011] In another embodiment of the rotation detector described above, the rotor has a base fixed to one axial side of the inner ring and extending radially outward, with the output coil provided on one axial side of the base, and the stator has a cover member located on one axial side with respect to the rotor, with the detection coil provided on the other axial side of the cover member.

[0012] In this design, the base of the rotor is formed separately from the inner ring, and the base is fixed to the inner ring. Therefore, compared to a design where the flange is integrally formed from the same material as the inner ring, this design offers the advantage of simpler rotor manufacturing. Furthermore, it becomes easier to change the shape and thickness of the base.

[0013] In another embodiment of the rotation detector described above, the rotor has a first extension extending from one axial side of the inner ring to the other axial side, and the output coil is provided on the radially outer surface of the first extension; the stator has a second extension extending from one axial side of the outer ring to the other axial side, and a first fixing member extending radially inward from the second extension, and the detection coil is provided on the radially inner surface of the first fixing member.

[0014] Since the first and second extensions extend in the axial direction, the first fixing member can be attached to the second extension by inserting it axially into the gap between the first and second extensions. This has the advantage of simplifying the manufacturing of the stator.

[0015] In another embodiment of the rotation detector described above, the rotor comprises a second fixing member fixed to the inner ring, the second fixing member having a first portion attached to the inner circumference of the inner ring and a second portion located on one side in the axial direction with respect to the inner ring and extending radially outward from the first portion on the one side in the axial direction, the output coil being provided on the axial side of the second portion, and the stator having a cover member located on one side in the axial direction with respect to the rotor, the detection coil being provided on the other side in the axial direction of the cover member.

[0016] In this disclosure, a second fixing member having a first portion and a second portion is fixed to the inner ring. Since the second portion extends radially outward from one axial side of the first portion, the rigidity of the second fixing member is increased. Therefore, the wobble of the second portion when the rotor rotates is suppressed, and the air gap between the second portion and the cover member can be set to a smaller size. Furthermore, the second fixing member is formed separately from the inner ring, and by moving the second fixing member in the axial direction, the first portion is attached to the inner circumference side of the inner ring. Thus, there is an advantage in that the manufacturing of the rotor is simplified.

[0017] In another embodiment of the rotation detector described above, the bearing is housed in a case, the rotor has a third extension extending from one axial side of the inner ring to the other axial side, the output coil is provided on the radially outer surface of the third extension, and the stator is provided in the case, with the detection coil provided on the surface facing the output coil.

[0018] In this disclosure, a third extension extending axially is formed on the inner ring of the rotor, an output coil is provided on the outer circumferential surface of the third extension, and a detection coil is provided on the inner circumferential surface of the case lid. In this way, even in an embodiment in which the bearing is housed in a case, a more compact rotation detector can be provided by integrating the rotor and stator with the bearing. [Effects of the Invention]

[0019] According to the present disclosure, a more miniaturized rotation detector can be provided.

Brief Description of the Drawings

[0020] [Figure 1] FIG. 1 is a perspective view of the rotation detector according to the first embodiment. [Figure 2] FIG. 2 is a side view of FIG. 1. [Figure 3] FIG. 3 is a front view of FIG. 1. [Figure 4] FIG. 4 is a perspective view of the rotation detector according to the first embodiment. [Figure 5] FIG. 5 is a cross-sectional view taken along line V-V of FIG. 3. [Figure 6] FIG. 6 is a perspective view of the rotation detector according to the second embodiment. [Figure 7] FIG. 7 is a side view of FIG. 6. [Figure 8] FIG. 8 is a front view of FIG. 6. [Figure 9] FIG. 9 is a perspective view of the rotation detector according to the second embodiment. [Figure 10] FIG. 10 is a cross-sectional view taken along line X-X of FIG. 8. [Figure 11] FIG. 11 is a perspective view of the rotation detector according to the third embodiment. [Figure 12] FIG. 12 is a side view of FIG. 11. [Figure 13] FIG. 13 is a rear view of FIG. 11. [Figure 14] FIG. 14 is a perspective view of the rotation detector according to the third embodiment. [Figure 15] FIG. 1 (should be FIG. 15) is a cross-sectional view taken along line XV-XV of FIG. 13. [Figure 16] FIG. 16 is a perspective view of the rotation detector according to the fourth embodiment. [Figure 17] FIG. 17 is a side view of FIG. 16. [Figure 18] FIG. 18 is a front view of FIG. 16. [Figure 19] FIG. 19 is a perspective view of the rotation detector according to the fourth embodiment. [Figure 20] Note: There seems to be a mistake in the original text where it says "FIG. 1" in the description of FIG. 15's cross-sectional view reference. It should probably be "FIG. 15". This has been corrected in the translation.Figure 20 is a cross-sectional view taken along the line XX-XX in Figure 18. [Figure 21] Figure 21 is a perspective view of the rotation detector according to the fifth embodiment. [Figure 22] Figure 22 is a side view of Figure 21. [Figure 23] Figure 23 is a cross-sectional view of Figure 22. [Figure 24] Figure 24 is a perspective view of the support shown in Figure 22. [Figure 25] Figure 25 is a cross-sectional view taken along the line XXV-XXV in Figure 24. [Modes for carrying out the invention]

[0021] Embodiments for carrying out the invention will be described in detail with reference to the drawings. The present invention is not limited to the contents described in the following embodiments. Furthermore, the components described below include those that can be easily imagined by those skilled in the art and those that are substantially the same. Moreover, the components described below can be combined as appropriate. In the drawings, the X direction is the axial direction of the central axis AX, the X1 side is one side in the axial direction and the X2 side is the other side in the axial direction. Furthermore, the rotation detector according to the present invention is, for example, a resolver, and the following embodiments will describe a rotation detector relating to a resolver.

[0022] [First Embodiment] First, the first embodiment will be described. Figure 1 is a perspective view of the rotation detector of the first embodiment. Figure 2 is a side view of Figure 1. Figure 3 is a front view of Figure 1. Figure 4 is a perspective view of the rotation detector of the first embodiment. Figure 5 is a cross-sectional view of Figure 3 along the VV line. This will be described in detail below.

[0023] As shown in Figures 1 to 4, the rotation detector 100 of the first embodiment includes a bearing 4, a cover member 62, and a signal output line 110.

[0024] As shown in Figures 1 to 4, the bearing 4 is provided in an annular shape along the axial direction of the central axis AX. The axial direction of the central axis AX is the X direction. A cover member 62 is attached to the X1 side of the bearing 4. The cover member 62 is rectangular when viewed from the X direction. As shown in Figure 3, the cover member 62 is larger than the bearing 4 when viewed from the X direction. Through holes 621 are provided at the four corners of the cover member 62. The rotation detector 100 can be attached to the housing (not shown) by inserting bolts (not shown) into the through holes 621 of the cover member 62 and fastening them to the housing. A rotation angle signal is output from the detection coil 52 to the signal output line 110. Note that the number of through holes 621 in the cover member 62 may be other than four (two, three, five, six or more). Also, the cover member 62 may not be rectangular when viewed from the axial direction.

[0025] As shown in Figure 5, the rotation detector 100 of the first embodiment comprises a rotor 2, a stator 3, an output coil 51, and a detection coil 52. The rotation detector according to the present invention is integrated with a bearing having an inner ring and an outer ring. The configuration of the rotation detector 100 will be described below.

[0026] The rotor 2 has a flange 61. In other words, in this embodiment, the flange 61 is the rotor 2.

[0027] The bearing 4 has an inner ring 41, rolling elements 42, and an outer ring 43. The inner ring 41 and the outer ring 43 extend in an annular shape around the axis of the central axis AX. The outer ring 43 is prevented from rotating, while the inner ring 41 rotates around the axis of the central axis AX. The flange 61 extends radially outward from a portion 411 on the X1 side (one side in the axial direction) of the inner ring 41. The flange 61 is formed integrally with the inner ring 41 from the same material as the inner ring 41. In a cross-section including the central axis AX, the inner ring 41 and the flange 61 are L-shaped. An output coil 51 and a receiving transformer 54 are provided on the X1 side surface of the flange 61. The output coil 51 is located radially outward from the receiving transformer 54.

[0028] The stator 3 has a cover member 62. In other words, in this embodiment, the cover member 62 is the stator 3. The cover member 62 is located on the X1 side relative to the bearing 4. As shown in Figures 1 and 5, the cover member 62 has a flange 622 that protrudes toward the X2 side. The flange 622 is an annular shape that extends in the direction of the axis of the central axis AX. Here, the configuration of the housing to which the rotation detector 100 is mounted (not shown) will be briefly described. The housing has a mounting surface on the X2 side, and the flat portion 620 of the cover member 62 shown in Figure 1 abuts against this mounting surface. The mounting surface is provided with four screw holes (female threads) corresponding to the through holes 621. The housing also has an inner diameter portion that is recessed toward the X2 side. This inner diameter portion of the housing fits with the outer circumferential surface of the outer ring 43 of the bearing 4. A projection is formed in the inner diameter portion of the housing that protrudes radially inward, and this projection abuts against the X2 side end face of the outer ring 43 of the bearing 4. Therefore, when a bolt is inserted into the through hole 621 shown in Figure 1 and fastened to the threaded hole (female thread) on the mounting surface, the outer ring 43 of the bearing 4 is pressed in the X direction by the X2-side end face of the flange 622 of the cover member 62 shown in Figure 5 and the protruding part of the housing. In other words, the outer ring 43 of the bearing 4 is clamped between the X2-side end face of the flange 622 and the protruding part of the housing. As a result, the outer ring 43 of the bearing 4 is fixed to the housing. Thus, in this embodiment, the cover member 62 is a retaining member for the outer ring 43, and the stator 3 is attached to this retaining member. Therefore, the outer ring 43 of the bearing 4 and the flange 622 of the cover member 62 and the inner diameter of the housing form a spigot structure, ensuring coaxiality between the outer ring 43 and the flange 622 with respect to the inner diameter of the housing. Furthermore, since the X2-side end face of the flange 622 of the cover member 62 and the X1-side end face of the outer ring 43 of the bearing 4 are in contact with each other on a flat plane, parallelism between the cover member 62 and the outer ring 43 of the bearing 4 can also be ensured. In addition, a detection coil 52 and a transmitting transformer 53 are provided on the X2-side surface of the cover member 62. The detection coil 52 is located radially outward from the transmitting transformer 53. The detection coil 52 faces the output coil 51 in the X direction (axial direction). The transmitting transformer 53 faces the receiving transformer 54 in the X direction (axial direction).As described above, the rotation detector 100 includes an output coil 51 provided on the rotor 2 and a detection coil 52 provided on the stator 3 and facing the output coil 51 in the axial direction. In this invention, the output coil 51 may be located radially inward from the receiving transformer 54, and the detection coil 52 may be located radially inward from the transmitting transformer 53. That is, the detection coil 52 may face the output coil 51, and the transmitting transformer 53 may face the receiving transformer 54. The same configuration may also be adopted for the second to fourth embodiments.

[0029] Furthermore, as shown in Figure 5, if the object to be detected is, for example, a motor, the output shaft 120 of the motor is fitted onto the inner circumferential surface 412 of the inner ring 41 of the bearing 4. As a result, the output shaft 120, the inner ring 41, and the flange 61 rotate together as a single unit. The output coil 51 and the detection coil 52 are arranged at equal intervals in the circumferential direction around the central axis AX. However, the present invention is not limited to this, and the output coil 51 and the detection coil 52 may be arranged at unequal intervals in the circumferential direction around the central axis AX.

[0030] Let's briefly explain the operation of this configuration. First, as shown in Figure 5, when an AC voltage is applied to the transmitting transformer 53, the receiving transformer 54 is energized with an AC voltage, and then the output coil 51 is energized with an AC voltage. Then, a signal corresponding to the rotation angle of the detection coil 52 is output from the detection coil 52 via the signal output line 110.

[0031] As described above, the rotation detector 100 according to the first embodiment includes a rotor 2 attached to the inner ring 41, a stator 3 facing the rotor 2, an output coil 51 provided on the rotor 2, and a detection coil 52 provided on the stator 3 and facing the output coil 51.

[0032] As mentioned above, in the rotation detector described in Patent Document 1, the rotor, stator, and bearings are separate components. Furthermore, the rotor and stator and the bearings are spaced apart in the axial direction. Therefore, the rotation detector described in Patent Document 1 may be large in size.

[0033] In contrast, the rotation detector 100 according to the first embodiment is integrated with the bearing 4. More specifically, in the rotation detector 100, the rotor 2 is attached to the inner ring 41, and the stator 3 faces the rotor 2. Therefore, the first embodiment provides a rotation detector 100 that is smaller than the rotation detector of Patent Document 1.

[0034] The rotor 2 is integrally formed from the same material as the inner ring 41 and has a flange 61 extending radially outward from a portion 411 on the X1 side (one side in the axial direction) of the inner ring 41. An output coil 51 is provided on the X1 side surface of the flange 61. The stator 3 has a cover member 62 located on the X1 side relative to the rotor 2. A detection coil 52 is provided on the X2 side surface of the cover member 62.

[0035] The flange 61 on the rotor 2 is integrally formed from the same material as the inner ring 41, and the stator 3 faces the rotor 2. An output coil 51 is provided on the flange 61, and a detection coil 52 is provided on the cover member 62. By integrating the rotor 2 and stator 3 with the bearing 4 in this way, a more compact rotation detector 100 can be provided. In particular, since the flange 61 is integrally formed from the same material as the inner ring 41, the mounting rigidity of the flange 61 to the inner ring 41 is increased, and the wobble of the flange 61 when the rotor 2 rotates is suppressed, so that the air gap between the flange 61 and the cover member 62 can be set to a smaller size.

[0036] [Second Embodiment] Next, a second embodiment will be described. Figure 6 is a perspective view of the rotation detector of the second embodiment. Figure 7 is a side view of Figure 6. Figure 8 is a front view of Figure 6. Figure 9 is a perspective view of the rotation detector of the second embodiment. Figure 10 is a cross-sectional view taken along line XX of Figure 8.

[0037] As shown in Figures 6 to 9, the rotation detector 100A of the second embodiment includes a bearing 4A, a cover member 62A, and a signal output line 110.

[0038] As shown in Figures 6 to 9, the bearing 4A is provided in an annular shape along the direction of the central axis AX. A cover member 62A is attached to the X2 side of the bearing 4A. The cover member 62A is annular when viewed from the X direction. A rotation angle signal is output from the detection coil 52 to the signal output line 110.

[0039] As shown in Figure 10, the rotation detector 100A of the second embodiment comprises a rotor 2A, a stator 3A, an output coil 51, and a detection coil 52. The rotation detector according to the present invention is integrated with a bearing having an inner ring and an outer ring. The configuration of the rotation detector 100A will be described below.

[0040] The rotor 2A has a base 63. In other words, in this embodiment, the base 63 is the rotor 2A.

[0041] The bearing 4A has an inner ring 41A, rolling elements 42, and an outer ring 43A. The inner ring 41A and the outer ring 43A extend in an annular shape around the axis of the central shaft AX. The outer ring 43A is prevented from rotating, while the inner ring 41A rotates around the axis of the central shaft AX. The base 63 is fixed to the X1 side portion (one side in the axial direction) 411 of the inner ring 41A and extends radially outward. The fixing method is preferably press-fit, spline, adhesive, etc., but is not limited to these. More specifically, the X1 side portion 411 has a stepped portion 411a on its outer circumference. The stepped portion 411a has an outer circumference portion 411b and a bottom portion 411c. The bottom portion 411c extends radially outward from the X2 side end of the outer circumference portion 411b. The inner circumference end portion 63a of the base 63 has a protruding shape that faces X2 and is fitted into the stepped portion 411a. In a cross-section including the central axis AX, the inner ring 41A and the base 63 are L-shaped. An output coil 51 and a receiving transformer 54 are provided on the X1 side surface of the base 63. The output coil 51 is located radially outward from the receiving transformer 54.

[0042] The stator 3A has a cover member 62A. In other words, in this embodiment, the cover member 62A is the stator 3A. The outer ring 43A has a protrusion 43A1 that projects toward the X1 side. The cover member 62A is located toward the X1 side relative to the bearing 4A. As shown in Figures 6 and 10, the cover member 62A has a flange 622A that projects toward the X2 side. The flange 622A is annular in shape and extends in the direction of the axis of the central axis AX. The flange 622A is fitted to the outer circumference of the protrusion 43A1 of the outer ring 43A and fixed to the outer ring 43A. A detection coil 52 and a transmitting transformer 53 are provided on the X2 side surface of the cover member 62A. The detection coil 52 is located radially outward relative to the transmitting transformer 53. The detection coil 52 faces the output coil 51 in the X direction (axial direction). The transmitting transformer 53 faces the receiving transformer 54 in the X direction (axial direction). As described above, the rotation detector 100A includes an output coil 51 provided on the rotor 2A and a detection coil 52 provided on the stator 3A and facing the output coil 51 in the axial direction.

[0043] Furthermore, as shown in Figure 10, if the object to be detected is, for example, a motor, the output shaft 120 of the motor is fitted onto the inner circumferential surface 412 of the inner ring 41A of the bearing 4A. As a result, the output shaft 120, the inner ring 41A, and the cover member 62A rotate together as a single unit.

[0044] As described above, in the rotation detector 100A according to the second embodiment, the rotor 2A has a base 63 fixed to the X1 side portion of the inner ring 41A and extending radially outward. An output coil 51 is provided on the X1 side surface of the base 63. The stator 3A has a cover member 62A located on the X1 side relative to the rotor 2A. A detection coil 52 is provided on the X2 side surface of the cover member 62A.

[0045] In the rotor 2A, the base 63 is formed separately from the inner ring 41A, and the base 63 is fixed to the inner ring 41A. Therefore, compared to the embodiment in which the flange 61 is integrally formed from the same material as the inner ring 41, this has the advantage of simplifying the manufacturing of the rotor 2A. In addition, it becomes easier to change the shape and thickness of the base 63. For example, since the height of the inner circumference end 63a of the base 63 is constant, the thickness of the base 63 can be reduced while maintaining the mounting rigidity of the base 63 to the inner ring 41A. In this way, in the second embodiment as well, a more compact rotation detector 100A can be provided by integrating the rotor 2A and stator 3A with the bearing 4A.

[0046] [Third Embodiment] Next, a third embodiment will be described. Figure 11 is a perspective view of the rotation detector of the third embodiment. Figure 12 is a side view of Figure 11. Figure 13 is a rear view of Figure 11. Figure 14 is a perspective view of the rotation detector of the third embodiment. Figure 15 is a cross-sectional view of Figure 13 taken along the line XV-XV.

[0047] As shown in Figures 11 to 14, the rotation detector 100B of the third embodiment includes a bearing 4B, a first fixing member 66, and a signal output line 110.

[0048] As shown in Figures 11 to 14, the bearing 4B is provided in an annular shape along the axial direction of the central axis AX. The signal output line 110 outputs a rotation angle signal from the detection coil 52. As shown in Figure 14, the signal output line 110 is drawn out from the first fixing member 66 towards X2, then bent and extends radially outward. In this invention, the signal output line 110 does not have to be bent, and may extend in a straight line after being drawn out from the first fixing member 66 towards X2.

[0049] As shown in Figure 15, the rotation detector 100B of the third embodiment comprises a rotor 2B, a stator 3B, an output coil 51, and a detection coil 52. The rotation detector according to the present invention is integrated with a bearing having an inner ring and an outer ring. The configuration of the rotation detector 100B will be described below.

[0050] The rotor 2B has a first extension 64. In other words, in this embodiment, the first extension 64 is the rotor 2B.

[0051] The bearing 4B has an inner ring 41B, rolling elements 42, and an outer ring 43B. The inner ring 41B and the outer ring 43B extend in an annular shape around the axis of the central axis AX. The outer ring 43B is prevented from rotating, while the inner ring 41B rotates around the axis of the central axis AX. The first extension 64 extends from a portion 411 on the X1 side (one side in the axial direction) of the inner ring 41B toward the X1 side. The first extension 64 extends in an annular shape around the axis of the central axis AX. In this embodiment, the first extension 64 is integrally formed from the same material as the inner ring 41B, but the present invention is not limited to this, and the first extension 64 may be formed separately from the inner ring 41B and fixed to the inner ring 41B by, for example, welding. In a cross-section including the central axis AX, the inner ring 41B and the first extension 64 are I-shaped. An output coil 51 and a receiving transformer 54 are provided on the outer circumferential surface (radially outward surface) of the first extension 64. The output coil 51 is located on the X1 side relative to the receiving transformer 54.

[0052] The stator 3B has a second extension 65 and a first fixing member 66. A stepped portion 65a is provided at the boundary between the outer ring 43B and the second extension 65. Specifically, since the inner circumferential surface of the second extension 65 is located radially outward from the inner circumferential surface of the outer ring 43B, a stepped portion 65a is formed at the boundary between the outer ring 43B and the second extension 65. The first fixing member 66 is fitted in contact with the inner circumferential surface of the second extension 65 and the bottom of the stepped portion 65a. In this way, the first fixing member 66 is fixed to the outer ring 43B. A detection coil 52 and a transmitting transformer 53 are provided on the inner circumferential surface of the first fixing member 66. The detection coil 52 is located on the X1 side relative to the transmitting transformer 53. The detection coil 52 faces the output coil 51 radially. The transmitting transformer 53 faces the receiving transformer 54 radially. As described above, the rotation detector 100B includes an output coil 51 provided on the rotor 2B and a detection coil 52 provided on the stator 3B and facing the output coil 51 in the radial direction.

[0053] Furthermore, as shown in Figure 15, if the object to be detected is, for example, a motor, the output shaft 120 of the motor is fitted to the inner surface 412 of the inner ring 41B of the bearing 4B and the inner surface of the first extension 64. As a result, the output shaft 120, the inner ring 41B, and the first extension 64 rotate together as a single unit.

[0054] As described above, in the rotation detector 100B according to the third embodiment, the rotor 2B has a first extension 64 extending from the X1 side portion of the inner ring 41B toward the X1 side. An output coil 51 is provided on the radially outer surface of the first extension 64. The stator 3B has a second extension 65 extending from the X1 side portion of the outer ring 43B toward the X1 side, and a first fixing member 66 extending radially inward from the second extension 65. A detection coil 52 is provided on the radially inner surface of the first fixing member 66.

[0055] Since the first extension 64 and the second extension 65 extend in the X direction, the first fixing member 66 can be assembled to the second extension 65 by inserting the first fixing member 66 along the X direction into the gap between the first extension 64 and the second extension 65. This has the advantage of simplifying the manufacturing of the stator 3B. In this way, even in the third embodiment, a smaller rotation detector 100B can be provided by integrating the rotor 2B and the stator 3B with the bearing 4B.

[0056] [Fourth Embodiment] Next, a fourth embodiment will be described. Figure 16 is a perspective view of the rotation detector of the fourth embodiment. Figure 17 is a side view of Figure 16. Figure 18 is a front view of Figure 16. Figure 19 is a perspective view of the rotation detector of the fourth embodiment. Figure 20 is a cross-sectional view taken along the line XX-XX in Figure 18. This will be described in detail below.

[0057] As shown in Figures 16 to 19, the rotation detector 100C of the fourth embodiment includes a bearing 4C, a cover member 62, and a signal output line 110.

[0058] As shown in Figures 16 to 19, the bearing 4C is provided in an annular shape along the axial direction of the central axis AX. A cover member 62 is attached to the X2 side of the bearing 4C. A rotation angle signal is output from the detection coil 52 to the signal output line 110.

[0059] As shown in Figure 20, the rotation detector 100C of the fourth embodiment comprises a rotor 2C, a stator 3C, an output coil 51, and a detection coil 52. The rotation detector according to the present invention is integrated with a bearing having an inner ring and an outer ring. The configuration of the rotation detector 100C will be described below.

[0060] The rotor 2C has a second fixing member 67. In other words, in this embodiment, the second fixing member 67 is the rotor 2C.

[0061] The bearing 4C has an inner ring 41C, rolling elements 42, and an outer ring 43. The inner ring 41C and the outer ring 43 extend in an annular shape around the axis of the central axis AX. The outer ring 43 is prevented from rotating, while the inner ring 41C rotates around the axis of the central axis AX. The second fixing member 67 has a first portion 671 and a second portion 672. In a cross-section including the central axis AX, the first portion 671 and the second portion 672 are L-shaped. The first portion 671 and the second portion 672 may be integrally molded from the same material, or they may be formed separately and then fixed by welding or the like. The second fixing member 67 extends in an annular shape around the axis of the central axis AX. The first portion 671 is fitted to the inner circumferential surface of the inner ring 41C. The second portion 672 is located on the X1 side relative to the inner ring 41C. The second portion 672 extends radially outward from the X1-side end of the first portion 671. The second portion 672 may abut the X1-side surface of the inner ring 41C. The X1-side surface of the second portion 672 is provided with an output coil 51 and a receiving transformer 54. The output coil 51 is located radially outward from the receiving transformer 54.

[0062] The stator 3C has a cover member 62. In other words, in this embodiment, the cover member 62 is the stator 3C. The cover member 62 is located on the X1 side relative to the bearing 4C. The flange 622 is an annular shape extending in the direction of the axis of the central axis AX. The flange 622 is fixed to the outer ring 43 via bolts (not shown). Here, the configuration of the housing (not shown) to which the rotation detector 100C is mounted will be briefly described. The housing has a mounting surface on the X2 side, and the cover member 62 shown in Figure 19 is attached to this mounting surface in contact with it. The mounting surface has four screw holes (female threads) corresponding to the through holes 621. The housing also has an inner diameter portion that is recessed toward the X2 side. This inner diameter portion of the housing fits with the outer circumferential surface of the outer ring 43 of the bearing 4. A projection is formed in the inner diameter portion of the housing that protrudes radially inward, and this projection contacts the X2 side end face of the outer ring 43 of the bearing 4. Therefore, when a bolt is inserted into the through hole 621 shown in Figure 19 and fastened to the threaded hole (female thread) on the mounting surface, the outer ring 43 of the bearing 4 is pressed in the X direction by the X2-side end face of the flange 622 of the cover member 62 shown in Figure 20 and the protruding part of the housing. In other words, the outer ring 43 of the bearing 4 is clamped between the X2-side end face of the flange 622 and the protruding part of the housing. As a result, the outer ring 43 of the bearing 4 is fixed to the housing. Thus, in this embodiment, the cover member 62 is a retaining member for the outer ring 43, and the stator 3 is attached to this retaining member. Therefore, the outer ring 43 of the bearing 4 and the flange 622 of the cover member 62 and the inner diameter of the housing form a spigot structure, ensuring coaxiality of the outer ring 43 and flange 622 with respect to the inner diameter of the housing. Furthermore, since the X2-side end face of the flange 622 of the cover member 62 and the X1-side end face of the outer ring 43 of the bearing 4 are in contact with each other on a flat plane, parallelism between the cover member 62 and the outer ring 43 of the bearing 4 can also be ensured. In addition, a detection coil 52 and a transmitting transformer 53 are provided on the X2-side surface of the cover member 62. The detection coil 52 is located radially outward from the transmitting transformer 53. The detection coil 52 faces the output coil 51 in the X direction (axial direction). The transmitting transformer 53 faces the receiving transformer 54 in the X direction (axial direction).As described above, the rotation detector 100C comprises an output coil 51 provided on the rotor 2 and a detection coil 52 provided on the stator 3 and facing the output coil 51 in the axial direction.

[0063] As described above, in the rotation detector 100C according to the fourth embodiment, the rotor 2C includes a second fixing member 67 fixed to the inner ring 41C. The second fixing member 67 has a first portion 671 attached to the inner circumference side of the inner ring 41C, and a second portion 672 located on the X1 side relative to the inner ring 41C and extending radially outward from the X1 side portion of the first portion 671. An output coil 51 is provided on the X1 side surface of the second portion 672. The stator 3C includes a cover member 62 located on the X1 side relative to the rotor 2C. A detection coil 52 is provided on the X2 side surface of the cover member 62.

[0064] In the fourth embodiment, a second fixing member 67 having a first portion 671 and a second portion 672 is fixed to the inner ring 41C. Since the second portion 672 extends radially outward from the X1 side portion of the first portion 671, the rigidity of the second fixing member 67 is increased. Therefore, the wobble of the second portion 672 when the rotor 2C rotates is suppressed, and the air gap between the second portion 672 and the cover member 62 can be set to a smaller size. In addition, the second fixing member 67 is formed separately from the inner ring 41C, and by moving the second fixing member 67 in the X direction, the first portion 671 is attached to the inner circumference side of the inner ring 41C. Thus, there is an advantage in that the manufacturing of the rotor 2C is made simpler. In this way, even in the fourth embodiment, a smaller rotation detector 100C can be provided by integrating the rotor 2C and stator 3C with the bearing 4C.

[0065] [Fifth Embodiment] Next, a fifth embodiment will be described. Figure 21 is a perspective view of the rotation detector of the fifth embodiment. Figure 22 is a side view of Figure 21. Figure 23 is a cross-sectional view of Figure 22. Figure 24 is a perspective view of the support of Figure 22. Figure 25 is a cross-sectional view of Figure 24 taken along the line XXV-XXV. Figures 22 and 23 are views of Figure 21 taken from direction P.

[0066] In the fifth embodiment, an example in which a rotation detector is applied to the ball screw device 8 is described, as shown in Figures 21 to 23. The ball screw device 8 comprises a screw shaft 81, a nut 82, a support 83, and a support 84.

[0067] As shown in Figures 21 to 23, a male thread is formed on the outer circumference of the screw shaft body 810 of the screw shaft 81, and a female thread is formed on the inner circumference of the nut 82, with the male thread of the screw shaft body 810 of the screw shaft 81 engaging with the female thread of the nut 82. A motor (not shown) is connected to the screw shaft 81, and the rotation of the screw shaft 81 causes the nut 82 to move linearly in the X direction. As shown in Figure 23, one end 811 of the screw shaft 81 is rotatably supported by a support 83, and the other end 812 of the screw shaft 81 is rotatably supported by a support 84. A large diameter portion 813, a medium diameter portion 816, and a small diameter portion 814 are formed on one end 811 of the screw shaft 81. The large diameter portion 813 has a larger diameter than the medium diameter portion 816, and the medium diameter portion 816 has a larger diameter than the small diameter portion 814. A medium-diameter portion 816 is positioned adjacent to the large-diameter portion 813 on the X1 side, and a small-diameter portion 814 is positioned adjacent to the medium-diameter portion 816 on the X1 side. A male thread is formed on the outer circumference of the X1-side end 816a of the medium-diameter portion 816, and a female thread is formed on the inner circumference of the nut 815, with the nut 815 engaging with the end 816a.

[0068] As shown in Figures 24 and 25, the bearings 4D and 4E are housed in the case 7. A detailed description follows. The case 7 has a cylindrical portion 71 and a cover portion 72. The cylindrical portion 71 has a main body portion 711 and a flange 712. The cylindrical portion 71 extends in the direction of the central axis AX. The X2-side end of the main body portion 711 is formed as a bent portion 713 that bends radially inward. The flange 712 extends radially outward from the X1-side end of the main body portion 711. The flange 712 is substantially rectangular when viewed from the X direction. The cover portion 72 is located on the X1 side relative to the cylindrical portion 71. The cover portion 72 has a convex portion 72a on the inner circumference side of the X2-side surface. The convex portion 72a has a shape that protrudes toward the X2 side. As shown in Figure 24, the cover portion 72 is fastened to the flange 712 via a plurality of bolts 72b.

[0069] The cylindrical portion 71 of case 7 houses two bearings 4D and 4E. Bearing 4D is positioned adjacent to bearing 4E on the X1 side. Bearing 4D has an inner ring 41D, rolling elements 42, and an outer ring 43D. A third extension 68 is provided extending from the X1 side portion of the inner ring 41D toward the X1 side. The third extension 68 extends in the direction of the axis of the central axis AX. The rotor 2D has the third extension 68. The inner ring 41D and the third extension 68 may be integrally molded from the same material, or they may be formed separately and then fixed by welding or the like. In a cross-section including the central axis AX, the inner ring 41D and the third extension 68 are I-shaped. An output coil 51 and a receiving transformer 54 are provided on the outer circumferential surface (radially outer surface) of the third extension 68. The output coil 51 is located on the X1 side relative to the receiving transformer 54. A detection coil 52 and a transmitting transformer 53 are provided on the inner circumferential surface of the lid portion 72. The detection coil 52 is located on the X1 side relative to the transmitting transformer 53. The detection coil 52 faces the output coil 51 in the radial direction. The transmitting transformer 53 faces the receiving transformer 54 in the radial direction. In this invention, the output coil 51 may be located on the X2 side relative to the receiving transformer 54, and the detection coil 52 may be located on the X2 side relative to the transmitting transformer 53. That is, the detection coil 52 may face the output coil 51, and the transmitting transformer 53 may face the receiving transformer 54.

[0070] Furthermore, when the cover portion 72 is fastened to the flange 712 via bolts 72b, the outer rings of bearing 4D and bearing 4E are pressed in the X direction by the protrusion 72a of the cover portion 72 and the bent portion 713 of the case 7. In other words, the outer rings of bearing 4D and bearing 4E are clamped in the X direction by the protrusion 72a of the cover portion 72 and the bent portion 713 of the case 7. Also, when a nut 815 is fastened to the end portion 816a of the medium diameter portion 816 of the screw shaft 81 shown in Figure 23, the third extension portion 68, the inner ring 41D of bearing 4D, and the inner ring of bearing 4E are pressed in the X direction by the large diameter portion 813 and the nut 815, as shown in Figures 23 and 25. As a result, the screw shaft 81, the third extension portion 68, the inner ring 41D of bearing 4D, and the inner ring of bearing 4E rotate together as a single unit.

[0071] Next, the support body 84 will be described. As shown in Figure 23, the other end 812 of the screw shaft 81 has a smaller diameter than the screw shaft body 810. The other end 812 is rotatably supported by the support body 84 via the bearing 4F. That is, the support body 84 is provided on the outer circumference side of the bearing 4F, and the other end 812 is provided on the inner circumference side of the bearing 4F. A protrusion 841 is provided at the X1 side end of the inner circumference of the support body 84, projecting radially inward. The protrusion 841 is located on the X1 side relative to the outer ring of the bearing 4F and is in contact with the outer ring of the bearing 4F. A cover body 842 is located on the X2 side relative to the outer ring of the bearing 4F. When the bolt 843 is fastened, the outer ring of the bearing 4F is pressed in the X direction by the cover body 842 and the protrusion 841, and the cover body 842, the protrusion 841 and the outer ring of the bearing 4F become one unit. Furthermore, the X2 end face of the screw shaft body 810 abuts against the inner ring of the bearing 4F on the X1 side. A ring member 844 is located on the X2 side relative to the inner ring of the bearing 4F, and a bolt 845 is located on the X2 side relative to the ring member 844. A male thread is formed on the outer circumference of the X2 end of the other end 812, which engages with the female thread on the inner circumference of the bolt 845. Therefore, when the bolt 845 is tightened, the inner ring of the bearing 4F is pressed in the X direction by the ring member 844 and the X2 end face of the screw shaft body 810. As a result, the bolt 845, ring member 844, screw shaft body 810, and inner ring of the bearing 4F rotate as a single unit.

[0072] Thus, in the rotation detector according to the fifth embodiment, the rotor 2D has a third extension 68. The stator 3D has a case 7. In other words, in this embodiment, the rotor 2D is the third extension 68, and the stator 3D is the cover 72 of the case 7. Although the fifth embodiment shows an example with two bearings, the number of bearings is not particularly limited and may be one or three or more.

[0073] As described above, in the fifth embodiment, the bearing 4D is housed in the case 7. The rotor 2D has a third extension 68 extending from the X1 side portion of the inner ring 41D toward the X1 side. An output coil 51 is provided on the radially outer surface of the third extension 68. The stator 3D is provided in the case 7, and a detection coil 52 is provided on the surface facing the output coil 51.

[0074] In the fifth embodiment, a third extension 68 (rotor 2D) extending in the X direction is formed on the inner ring 41D, an output coil 51 is provided on the outer circumferential surface of the third extension 68, and a detection coil 52 is provided on the inner circumferential surface of the lid 72 (stator 3D) of the case 7. In this embodiment, even when the bearing 4D is housed in the case 7, a more compact rotation detector can be provided by integrating the rotor 2D and stator 3D with the bearing 4D. [Explanation of Symbols]

[0075] 2, 2A, 2B, 2C, 2D rotors 3, 3A, 3B, 3C, 3D stator 4, 4A, 4B, 4C, 4D, 4E bearings 41, 41A, 41B, 41D inner ring 411 One side 411a Stepped section 411b Outer periphery 411c bottom 412 Inner surface 42 Rolling element 43, 43A, 43B, 43D outer ring 43A1 protrusion 51 Output coil 52 detection coils 53 Transmitting Transformer 54 Receiving Transformer 61 Flange 62, 62A Cover members 620 Plane section 621 Through hole 622 Flange 622A Flange 63 Pedestal 63a Inner circumference end 64 1st extension 65 Second extension 65a Stepped section 66 First fixing member 67 Second fixing member 671 Part 1 672 Part 2 68 Third extension 7 cases 71 Cylinder part 711 Main body 712 Flange 713 Bending section 72 Lid 72a Convex part 72b Bolt 8. Ball screw device 81 Screw shaft 811 One end 812 Other end 813 Large diameter section 814 Small diameter section 815 Nut 816 Medium diameter section 82 nuts 83 Support 84 Support 100, 100A, 100B, 100C Rotation Detector 110 Signal output line 120 Output shaft AX center axis

Claims

1. A rotational detector that is mounted on a bearing having an inner ring and an outer ring, A rotor attached to the inner ring, A stator facing the rotor, The output coil provided on the rotor, The stator is provided with a detection coil that is facing the output coil, Rotation detector.

2. The rotor is integrally formed from the same material as the inner ring and has a flange extending radially outward from one axial side of the inner ring, and the output coil is provided on one axial side of the flange. The stator has a cover member located on one side in the axial direction relative to the rotor, and the detection coil is provided on the other side in the axial direction of the cover member. The rotation detector according to claim 1.

3. The rotor has a base fixed to one axial side of the inner ring and extending radially outward, and the output coil is provided on one axial side of the base. The stator has a cover member located on one side in the axial direction relative to the rotor, and the detection coil is provided on the other side in the axial direction of the cover member. The rotation detector according to claim 1.

4. The rotor has a first extension that extends from one axial side of the inner ring to the other axial side, and the output coil is provided on the radially outer surface of the first extension. The stator has a second extension extending from one axial side of the outer ring to the other axial side, and a first fixing member extending radially inward from the second extension, with the detection coil provided on the radially inward surface of the first fixing member. The rotation detector according to claim 1.

5. The rotor comprises a second fixing member fixed to the inner ring, the second fixing member having a first portion attached to the inner circumference of the inner ring, and a second portion located on one side in the axial direction with respect to the inner ring and extending radially outward from the first portion on the one side in the axial direction, the output coil being provided on the one side in the axial direction of the second portion. The stator has a cover member located on one side in the axial direction relative to the rotor, and the detection coil is provided on the other side in the axial direction of the cover member. The rotation detector according to claim 1.

6. The bearing is housed in a case. The rotor has a third extension that extends from one axial side of the inner ring to the other axial side, and the output coil is provided on the radially outer surface of the third extension. The stator is provided in the case, and the detection coil is provided on the surface facing the output coil. The rotation detector according to claim 1.

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