Angle sensor

Abstract

[Problem] To provide an angle sensor capable of suppressing the influence of movement in an axial direction of a rotary shaft. [Solution] An angle sensor 1 comprises a rotor 2, a stator 3, and a frame 4. The rotor 2 has a cylinder 10 and a plurality of metal bodies 5 fixed to the cylinder 10. The frame 4 is fixed to the stator 3. The stator 3 comprises: a cylinder 30 having an inner peripheral surface 31 as an inner surface on the rotor 2 side, and an outer peripheral surface 32 as an outer surface on the frame 4 side; and a plurality of coils 20 attached to the outer peripheral surface 32 of the cylinder 30.

Description

Angle Sensor

[0001] The present invention relates to an angle sensor, and more particularly to an inductive angle sensor.

[0002] Conventionally, various sensors have been used to detect the rotation angle of a motor, etc. An inductive sensor is one of such angle sensors for detecting the rotation angle (see, for example, Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2019-200106

[0004] Conventional inductive sensors have room for improvement in terms of detection accuracy.

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide an angle sensor that can improve detection accuracy.

[0006] An angle sensor according to one aspect of the present invention comprises a tube, a rotor having a plurality of metal bodies fixed to the tube, a stator, and a frame fixed to the stator, wherein the stator comprises a tube having an inner surface on the rotor side and an outer surface on the frame side, and a plurality of coils attached to the outer surface of the tube.

[0007] 1 is a diagram schematically showing the configuration of an angle sensor according to an embodiment of the present invention, and is a transparent perspective view schematically showing the internal configuration by transmitting through some members of the angle sensor. FIG. 1 is a perspective view schematically showing the configuration of the angle sensor. FIG. 2 is a front view schematically showing the configuration of the angle sensor. FIG. 3 is a side view schematically showing the configuration of the angle sensor. FIG. 4 is a transparent perspective view showing a specific example of a rotor. FIG. 5 is a perspective view schematically showing the configuration of the stator. FIG. 6 is a side view schematically showing the configuration of the stator. FIG. 7 is a sectional view schematically showing a cross section taken along a plane including the axis of the stator. FIG. 8 is a perspective view of a coil structure. FIG. 9 is a perspective view schematically showing the configuration of the frame. FIG. 10 is a rear view schematically showing the configuration of the frame. FIG. 11 is a sectional view schematically showing a cross section taken along a plane including the axis x of the stator and frame in an attached state. FIG. 12 is a perspective view showing a modified example of the stator and frame. FIG. 13 is a perspective view showing a modified example of the stator.

[0008] An embodiment of the present invention will be described below with reference to the accompanying drawings. Note that in the drawings, not all of the components are designated by reference numerals, and some of the reference numerals of the components may be omitted. FIG. 1 is a diagram schematically illustrating the configuration of an angle sensor 1 according to an embodiment of the present invention, and is a transparent perspective view schematically illustrating the internal configuration by seeing through some of the components of the angle sensor 1. FIG. 2 is a perspective view schematically illustrating the configuration of the angle sensor 1, FIG. 3 is a front view schematically illustrating the configuration of the angle sensor 1, and FIG. 4 is a side view schematically illustrating the configuration of the angle sensor 1. As shown in FIGS. 1 to 4, the angle sensor 1 includes a rotor 2, a stator 3, and a frame 4. The rotor 2 includes a cylinder 10 and multiple metal bodies 5 fixed to the cylinder 10. The frame 4 is fixed to the stator 3. The stator 3 includes a cylinder 30 having an inner circumferential surface 31 serving as an inner surface facing the rotor 2 and an outer circumferential surface 32 serving as an outer surface facing the frame 4, and multiple coils 20 attached to the outer circumferential surface 32 of the cylinder 30. The configuration of the angle sensor 1 will be described in detail below. 2 to 4, the rotor 2 and the stator 3 are shown in a predetermined positional relationship. This predetermined positional relationship is an example of the positional relationship between the rotor 2 and the stator 3 when the angle sensor 1 is attached to an application object and in use. In the angle sensor 1, the rotor 2 is disposed inside the stator 3.

[0009] The metal body 5 as a conductor is made of a conductive metal material. The multiple metal bodies 5 are, for example, arranged in a circumferential direction around the axis x, which is the rotation axis of the angle sensor 1. As shown schematically in FIG. 1 , the multiple metal bodies 5 form a cylindrical shape (hereinafter referred to as a metal body structure 6) extending annularly around the axis x. The metal body structure 6 is a shape formed by the arrangement of the multiple metal bodies 5. The conductor may be a metal body or a component having a conductive material (a component capable of generating so-called eddy currents or induced currents (currents) within one surface), and the following description will use a metal body as an example. The metal body structure 6 may be embedded inside the cylinder 10 or provided on the surface of the cylinder 10. The metal body 5 has a portion extending along the axis x. The multiple metal bodies 5 may also be connected to each other. The multiple metal bodies 5 are connected by one or more connecting parts, and the one or more connecting parts may be formed from a non-conductive material (e.g., resin) or a conductive material (e.g., metal), and the multiple metal bodies 5 may be electrically connected.

[0010] As shown in FIGS. 2 to 4 , the cylinder 10 of the rotor 2 is a cylindrical member extending along the axis x. The cylinder 10 of the rotor 2 is attached to a rotating member of an external device to which the angle sensor 1 is applied, so that the axis x coincides or substantially coincides with the rotation axis of the rotating member of the external device. For example, as shown in FIGS. 2 to 4 , the cylinder 10 of the rotor 2 has an inner circumferential surface 11, which is a cylindrical surface extending along a cylindrical surface with the axis x as its central axis, and an outer circumferential surface 12, which is a cylindrical surface facing away from the inner circumferential surface 11 on the radially outer side (hereinafter also referred to as the "outer peripheral side"). The radial direction is a direction perpendicular to the axis x. The cylinder 10 also has end faces 13 and 14, which are surfaces facing in the respective directions in which the axis x extends. The inner circumferential surface 11 and the outer circumferential surface 12 extend between the end face 13 (at one end) and the end face 14 (at the other end). The angle sensor 1 is applied to, for example, a motor, the shaft of which passes through the inner circumferential surface 11 of the cylinder 10 of the rotor 2, and the rotor 2 is fixed to the shaft.

[0011] The cylinder 10 of the rotor 2 is made of, for example, a resin material, a non-magnetic material, or a non-conductive material. The resin material of the cylinder 10 is, for example, an epoxy-based resin (thermosetting resin). However, the material of the cylinder 10 may be other resins. For example, the material of the cylinder 10 may be a recyclable resin. Furthermore, the non-magnetic material may be non-conductive.

[0012] FIG. 5 is a see-through perspective view showing a specific example of the rotor 2. In FIG. 5, the interior of the cylinder 10 is shown in a see-through manner. As shown in FIG. 5, multiple metal bodies 5 are arranged in an annular shape, forming a metal body structure 6. Each metal body 5 extends in the axial direction x along the cylinder 10 and also in the circumferential direction along the cylinder 10, forming a plate-like shape facing radially and forming a surface facing the outer periphery. As shown in FIG. 5, the metal body 5 is, for example, a plate-like metal body whose cross section perpendicular to the axis x has a curved shape, specifically a circular arc or arc-like shape, and whose cross section perpendicular to the axis x is uniform or approximately uniform along the axis x. Specifically, for example, the metal body 5 has a curved shape (the shape of a cylinder or a part of an approximately cylinder) with the axis x as its central axis or approximately central axis, and has a constant or approximately constant width in the circumferential direction around the axis x. Also, as shown in FIG. 5, the multiple metal bodies 5 are arranged at predetermined distances in the circumferential direction of the cylinder 10. That is, two adjacent metal bodies 5 are spaced a predetermined distance apart around the axis x. The multiple metal bodies 5 are, for example, arranged at equal or approximately equal angular intervals in the circumferential direction along the surface of a cylinder whose central axis is the axis x. The shape of the metal bodies 5 is not limited to the above-described shape. As described above, the metal bodies 5 may be embedded in the tube 10 or provided on the surface of the tube 10. For example, the multiple metal bodies 5 may be arranged as shown in FIG. 5 and fixed to the outer peripheral surface 12 of the tube 10.

[0013] Furthermore, the metal bodies 5 each have, for example, two end portions and a portion (middle portion) between the two end portions in the circumferential direction. In the radial direction, the distance between the end portion of the metal body 5 and the outer peripheral surface 12 of the cylinder 10 of the rotor 2 is greater than the distance between the middle portion of the metal body 5 and the outer peripheral surface 12 of the cylinder 10 of the rotor 2, and the end portion of the metal body 5 is farther away from the outer peripheral surface 12 of the cylinder 10 of the rotor 10 than the middle portion.

[0014] FIG. 6 is a perspective view showing a schematic configuration of the stator 3, FIG. 7 is a side view showing a schematic configuration of the stator 3, and FIG. 8 is a cross-sectional view showing a schematic cross section of the stator 3 taken along a plane including the axis x. As shown in FIGS. 6 to 8 , the tube 30 of the stator 3 is a cylindrical member extending along the axis x and includes a portion of the tube (hereinafter referred to as the base) 33 and multiple protrusions 34. The base 33 includes an inner circumferential surface 31 and an outer circumferential surface 33a of the tube 30, which will be described later. The protrusions 34 protrude from the base 33 toward the outer periphery (outward in the radial direction r). The base 33 is provided with the protrusions 34 at equal or approximately equal angular intervals around the axis x, for example. The protrusions 34 protrude from the base 33 in the radial direction r, and the cross section perpendicular to the radial direction r is, for example, elliptical or approximately elliptical. Note that the cross-sectional shape of the protrusions 34 is not limited to an elliptical shape and may be other shapes.

[0015] The inner circumferential surface 31 of the cylinder 30 of the stator 3 is formed on a base 33. As shown in FIGS. 6 to 8 , the base 33 has the inner circumferential surface 31, which is a cylindrical surface extending along the axis x, and an outer circumferential surface 33a. The inner circumferential surface 31 and the outer circumferential surface 33a are opposite each other in the radial direction. The inner circumferential surface 31 of the base 33 forms a space capable of accommodating the rotor 2 therein, and faces the outer circumferential surface 12 of the cylinder 10 of the rotor 2 across an annular gap (magnetic gap). The inner circumferential surface 31 of the base 33 is, for example, a cylindrical surface extending along a cylindrical surface whose central axis is the axis x.

[0016] The outer peripheral surface 33a of the base 33 is, for example, a cylindrical surface extending along a cylindrical surface with the axis x as its central axis. The base 33 also has flange portions 35, 36, which are annular portions protruding outward from the outer peripheral surface 33a, as shown in FIGS. 6 to 8 . The flange portions 35 and 36 face each other in the direction of the axis x via the outer peripheral surface 33a. The protruding portion 34 is provided on the outer peripheral surface 33a and protrudes outward from the outer peripheral surface 33a. As shown in FIGS. 7 and 8 , a gap is formed between the protruding portion 34 and the flange portions 35, 36 in the direction of the axis x. The outer peripheral portion of the cylinder 30 of the stator 3 has an outer peripheral surface 32, which includes the outer peripheral surface 33a of the base 33 and the flanges 35, 36.

[0017] As shown in Figures 6 to 8, the flange portion 35 has an end face 35a, which is an annular surface facing the outer periphery. The end face 35a is, for example, a cylindrical surface extending along a cylindrical surface whose central axis is the axis x. The flange portion 36 also has an end face 36a, which is an annular surface facing the outer periphery. The end face 36a is, for example, a cylindrical surface extending along a cylindrical surface whose central axis is the axis x. The outer size (diameter) of the end face 35a of the flange portion 35 and the outer size (diameter) of the end face 36a of the flange portion 36 are the same or approximately the same. Note that the outer size (diameter) of the end face 35a of the flange portion 35 and the outer size (diameter) of the end face 36a of the flange portion 36 may be different. Hereinafter, the outer size will be referred to as the diameter.

[0018] 7 and 8, the tube 30 has an annular step 37 around the axis x. The step 37 is adjacent to the base 33 in the axis x direction and is formed on the side surface 33b of the base 33 on the flange 35 side, as shown in FIGS. 7 and 8. The side surface 33b of the base 33 is an annular surface facing the opposite side from the flange 36 in the axis x direction. The step 37 is an annular portion protruding from the side surface 33b in the axis x direction and forms a step surface 37a, which is an annular surface facing the outer periphery. The diameter of the step surface 37a is smaller than the diameter of the flange 35, for example. The step surface 37a is a cylindrical surface extending along a cylindrical surface with the axis x as its central axis. An annular recess 37b recessed toward the inner periphery is formed in the step surface 37a.

[0019] As described above, multiple coils 20 are attached to the outer peripheral surface 32 of the tube 30 of the stator 3. The coils 20 are formed of a conductor (conductive member) such as magnet wire, and the conductive member is made of a conductive material. Specifically, as shown in FIGS. 6 to 8 , multiple coils 20 are wound around multiple protrusions 34 on the base 33 of the tube 30, and the tube 30 is formed with a cylindrical shape extending annularly around the axis x (hereinafter referred to as a coil structure 7). The coil structure 7 is a shape formed by the arrangement of multiple coils 20. The coils 20 are, for example, coils formed by winding magnet wire. The coils 20 are formed by winding magnet wire around multiple protrusions 34. The coils 20 have an annular shape wound around the radial direction r of the tube 30 and surround a planar space facing the radial direction. The multiple coils 20 are arranged side by side around the axis x on the tube 30 of the stator 3, forming the coil structure 7.

[0020] FIG. 9 is a perspective view showing the coil structure 7. As shown in FIG. 9, the coil structure 7 has two pieces (hereinafter referred to as coil structure pieces) 7a and 7b. The coil structure piece 7a is formed by a plurality of coils 20a, which are coils 20, connected in series in an annular shape. Similarly, the coil structure piece 7b is formed by a plurality of coils 20b, which are coils 20, connected in series in an annular shape. That is, a plurality of annular coils 20a or 20b are arranged in the circumferential direction. The coil structure piece 7a and the coil structure piece 7b are formed of conductive materials. The coil structure piece 7a and the coil structure piece 7b are coated with, for example, an insulating material (an insulating film or coating) and are electrically insulated from each other. As shown in FIG. 9, the coil structure piece 7a and the coil structure piece 7b overlap each other in the radial direction to form the coil structure 7. In the coil structure pieces 7a and 7b, a portion of the space surrounded by the coil 20a is offset from a portion of the space surrounded by the coil 20b in the circumferential direction, and another portion of the space surrounded by the coil 20a is overlapped in the circumferential direction with another portion of the space surrounded by the coil 20b. Specifically, the space surrounded by the coil 20a is offset from the space surrounded by the coil 20b in the circumferential direction by half the width of the space surrounded by the coil 20a. The number of coils 20a and 20b in each of the coil structure pieces 7a and 7b corresponds to the axial multiplier angle set for the angle sensor 1. The number of coil structure pieces 7a and 7b also corresponds to the number of detection signals output by the coil structure 7.

[0021] As shown in Figures 6 to 9, a magnet wire is wound around each of the protruding portions 34 of the tube 30 of the stator 3 in the radial direction r, and a plurality of annular coils 20 are formed around the plurality of protruding portions 30 in the radial direction r, thereby forming a coil structure 7 in the stator 3. For example, each of the coil structure pieces 7a, 7b is formed by winding one magnet wire around the plurality of protruding portions 34 of the tube 30. Specifically, for example, for each of two adjacent protruding portions 34 toward one side in the circumferential direction, the magnet wire is wound around the protruding portions 34 alternately from one side in the axial x direction and the other side in the axial x direction, and after going around the tube 30 once, the magnet wire is turned back and wound around the protruding portions 34 once again toward the other side in the circumferential direction, thereby forming the coil structure pieces 7a, 7b. In this case, each of the coils 20a, 20b is formed around two protruding portions 34. Furthermore, the coil structure pieces 7a and 7b are offset from each other in the circumferential direction by one protrusion 34. Note that each of the coils 20a, 20b is not limited to being formed around two protrusions 34, but may be formed around other numbers of protrusions 34. While the magnet wire has been described as being wound around one circumference, the winding pattern of the magnet wire is not limited to this, and the magnet wire may be wound around two or more circumferences. In other words, the coil formed by winding the magnet wire may have multiple layers, such as one layer in the radial or axial direction, two layers, three layers, four layers, or five layers. In this case, the output signal or the signal to be detected (e.g., the amplitude of the signal waveform) can be amplified compared to the case of one circumference or one layer.

[0022] As shown in FIGS. 7 and 8, an excitation circuit 38 is housed in a recess 37b of the step portion 37 of the cylinder 30 of the stator 3.

[0023] The cylinder 30 of the stator 3 is made of an insulating material, for example, a resin material, and is integrally formed. The cylinder 30 of the stator 3 may also be made of, for example, a resin material, a non-magnetic material, or a non-conductive material. The non-magnetic material may be non-conductive. The resin material forming the cylinder 30 of the stator 3 is, for example, an epoxy resin (thermosetting resin). The material forming the cylinder 30 of the stator 3 may also be another resin.

[0024] Fig. 10 is a perspective view schematically showing the configuration of the frame 4, Fig. 11 is a rear view schematically showing the configuration of the frame 4, and Fig. 12 is a cross-sectional view schematically showing a cross section taken along a plane including the axis x of the frame 4. As described above, in the angle sensor 1, the frame 4 is fixed to the stator 3 and is capable of being fixed to the stator 3.

[0025] As shown in FIGS. 10 to 12 , the frame 4 has a cover 40 that covers the multiple coils 20 formed on the stator 3. The cover 40 is, for example, a cylindrical portion corresponding to the tube 30 of the stator 3. The cover 40 forms a space therein that can accommodate the tube 30 of the stator 3 and has an inner circumferential surface 41 that defines this space. The cover 40 also has an outer circumferential surface 42 that faces away from the inner circumferential surface 41 on the outer circumferential side. The inner circumferential surface 41 is a cylindrical surface that extends along the axis x, for example, a cylindrical surface that extends along a cylindrical surface with the axis x as its central axis. Specifically, the inner circumferential surface 41 of the cover 40 is formed to be able to accommodate the flange portions 35 and 36 of the tube 30 of the stator 3. When the tube 30 is accommodated in the space formed by the inner circumferential surface 41, the inner circumferential surface 41 faces radially the end faces 35 a and 36 a of the flange portions 35 and 36, respectively. The inner circumferential surface 41 of the cover 40 has an inner diameter such that, for example, when the tube 30 is accommodated in the space formed by the inner circumferential surface 41, it comes into contact with the end faces 35 a, 36 a of the flange portions 35, 36, respectively, and the tube 30 is press-fit into the space formed by the inner circumferential surface 41. Furthermore, the inner circumferential surface 41 of the cover 40 has a size (inner diameter) such that, for example, when the tube 30 is accommodated in the space formed by the inner circumferential surface 41, it does not come into contact with the end faces 35 a, 36 a of the flange portions 35, 36, respectively, and an annular gap is formed between the inner circumferential surface 41 and the end faces 35 a, 36 a.

[0026] 10 to 12, the cover 40 of the frame 4 is formed with a flange portion 43, which is an annular portion that protrudes inward from the inner circumferential surface 41. The flange portion 43 is formed, for example, at one end of the inner circumferential surface 41 in the direction of the axis x. When the tube 30 is housed in the space formed by the inner circumferential surface 41 of the cover 40, the flange portion 43 engages (contacts) with the tube 30 in the direction of the axis x, and serves as a stopper for the tube 30.

[0027] When the tube 30 is housed in the space formed by the inner circumferential surface 41 of the cover 40, the inner circumferential surface 41 of the cover 40 is configured to cover the entire tube 30. In other words, the width of the inner circumferential surface 41 of the cover 40 in the axial x direction is the same as or larger than the width of the tube 30 in the axial x direction. Note that when the tube 30 is housed in the space formed by the inner circumferential surface 41 of the cover 40, the inner circumferential surface 41 of the cover 40 does not have to cover the entire tube 30. In other words, the width of the inner circumferential surface 41 of the cover 40 in the axial x direction may be smaller than the width of the tube 30 in the axial x direction. For example, when the tube 30 is housed in the space formed by the inner circumferential surface 41 of the cover 40, the width of the inner circumferential surface 41 of the cover 40 in the axial x direction may be such that it covers the outer circumferential surface 33 a of the tube 30.

[0028] As shown in FIGS. 10 to 12 , the frame 4 has a mounting portion 44 that is attached to an external device as an application target. As shown in FIGS. 10 to 12 , the mounting portion 44 is provided, for example, on the outer peripheral surface 42 of the cover 40 and protrudes outward from the cover 40. The mounting portion 44 also has a hole 44a (hereinafter referred to as a through-hole) through which a fastening member such as a bolt is passed, allowing the mounting portion 44 to be attached to an external device via the fastening member. The frame 4 has, for example, three mounting portions 44. The number of mounting portions 44 on the frame 4 is not limited to this. As shown in FIGS. 10 to 12 , the cover 40 also has a holding portion 45 that is a portion that holds, for example, the substrate 8, a circuit such as an IC provided on the substrate 8, or an electric circuit having a calculation function. As shown in FIGS. 10 to 12 , the holding portion 45 extends from the outer peripheral surface 42 of the cover 40 along the axis x toward the other side of the axis x. 1, 2, and 4, in the angle sensor 1, the substrate 8 is attached to the holder 45 of the frame 4. For example, one or more electronic components and one or more wirings are provided on the substrate 8. These multiple electronic components may form a control unit that performs calculations or processing.

[0029] The frame 4 is formed, for example, from an insulating material, such as resin. The frame 4 is, for example, integrally molded. That is, each component of the frame 4, such as the cover 40, the mounting portion 44, and the holding portion 45, is integrally molded from the same material. Note that the frame 4 does not have to be integrally molded.

[0030] FIG. 13 is a cross-sectional view showing an assembled state in which the stator 3 and the frame 4 are assembled, with the frame 4 fixed to the stator 3. FIG. 13 shows a cross section taken along a plane including the axis x of the stator 3 and the frame 4 in the assembled state. As shown in FIG. 13 , the cylinder 30 of the stator 3 is housed in a space formed by the inner circumferential surface 41 of the cover 40 of the frame 4, and the frame 4 is fixed to the stator 3. The frame 4 is fixed to the stator 3 by, for example, engagement, fitting, or bonding. The frame 4 is fixed to the stator 3 by, for example, adhesive bonding. Note that the fixing configuration of the frame 4 to the stator 3 is not limited to these configurations. As shown in FIG. 13 , in the attached state, the entire cylinder 30 is covered by the cover 40 in the direction of the axis x. Note that, as described above, in the attached state, the entire cylinder 30 does not have to be covered by the cover 40 in the direction of the axis x. 13, in the attached state, the side surface 33b of the tube 30 is in contact with the flange portion 43 of the cover 40. Note that in the attached state, the side surface 33b of the tube 30 does not have to be in contact with the flange portion 43 of the cover 40.

[0031] In this manner, in the mounted state, the outer peripheral surface 32 of the tube 30 of the stator 3 is covered by the cover 40 of the frame 4. Therefore, in the mounted state, the coil structure 7 formed on the outer peripheral surface 32 of the tube 30 of the stator 3 is covered by the cover 40 of the frame 4. This makes it possible to protect the coil structure 7 without protecting it with potting or the like, and to prevent external objects from coming into contact with the coil structure 7. Furthermore, when the recess 37b of the step portion 37 of the tube 30 is covered by the cover 40, the excitation circuit 38 in the recess 37b can also be protected from external contact without protecting it with potting or the like.

[0032] As described above, FIGS. 2 to 4 show the angle sensor 1 in use. The multiple metal bodies 5 and the multiple coils 20 face each other in the radial direction with an annular gap between them. As shown in FIG. 4 , the width W1 of the metal body 5 is, for example, wider than the width W2 of the coil 20. Note that the width W1 is the distance of the metal body 20 in the axial x direction, and the width W2 is the distance of the coil 20 in the axial x direction. This allows the entire width of the coil 20 in the axial x direction to face the metal body 5 in the radial direction (see FIG. 4 ). The metal body 5 also protrudes beyond the coil 20 in both directions along the axial x direction (see FIGS. 2 and 4 ).

[0033] The rotor 2 and the stator 3 form an inductive angle sensor, and the multiple coils 20 form detection coils. A magnetic space or magnetic gap is formed between the rotor 2 and the stator 3. For example, in the angle sensor 1, a radially directed magnetic flux whose magnitude periodically changes acts on the multiple coils 20. Specifically, the excitation circuit 38 provided in the stator 3 is a magnetic circuit that generates a periodically changing magnetic flux acting on each of the multiple coils 20. Meanwhile, as described above, the multiple metal bodies 5 are arranged in the circumferential direction around the axis x, and cross the magnetic flux generated by the excitation circuit 38 as the rotor 2 rotates. Furthermore, the projection of the metal body 5, which has a portion extending along the axis x, onto the coils 20 in the radial direction moves as the rotor 2 rotates. Therefore, the magnetic flux from the excitation circuit 38 acting on each of the multiple coils 20 is affected by eddy currents generated in the metal bodies 5 and cancels out, periodically changing as the rotor 2 rotates. As a result, in the plurality of coils 20, an electromotive force is generated by electromagnetic induction which varies with the rotation of the rotor 2, and signals which vary with the rotation of the rotor 2 are detected from the plurality of coils 20. Based on the detection signals from the plurality of coils 20, the rotation angle of the rotor 2 is detected in a device having an electric circuit.

[0034] In the stator 3 of this angle sensor 1, the protrusions 34 protrude outward from the outer peripheral surface 33a of the base 33, and the magnet wire forming the coil structure pieces 7a, 7b can be wound around the multiple protrusions 34 from the outer peripheral side along the outer peripheral surface 33a. Therefore, the coil structure pieces 7a, 7b can have a smaller radial gap between the wound magnet wire and the tube 30 than the coil structure pieces 7a, 7b in which the magnet wire is wound from the inner peripheral side along the inner peripheral surface of the stator 3. In other words, the radial gap between the magnet wire and the outer peripheral surface 33a can be reduced. This allows the coil structure pieces 7a, 7b of the stator 3 to be shaped to fit more closely to the outer peripheral surface 33a, i.e., to fit more closely to a cylindrical surface. Therefore, the coil structure pieces 7a, 7b of the stator 3 can be shaped more closely to a desired shape, thereby improving the detection accuracy of the angle sensor 1.

[0035] The angle sensor 1 has the above-described configuration, and each metal body 5 faces in the radial direction. Therefore, the metal bodies 5 can suppress the influence of movement of the rotor 2 in the axial x direction. For example, the rigidity of the metal bodies 5 against vibrations of the rotor 2 in the axial x direction is increased, which increases the accuracy of the angle sensor 1 and also increases the strength of the metal bodies 5 against vibrations of the rotor 2 in the axial x direction. Furthermore, when the metal bodies 5 are embedded in the cylinder 10 of the rotor 2 and are located inside the cylinder 10, the strength of the metal bodies 5 against vibrations of the rotor 2 in the axial x direction is also increased in this respect.

[0036] Furthermore, the cylinder 10 of the rotor 2 is cylindrical and extends along the axis x, and even if the radial thickness is reduced, the strength of the cylinder 10 against vibration in the direction of the axis x of the rotor 2 can be maintained at a high level. This allows the radial thickness of the cylinder 10 to be reduced, making the rotor 2 lighter and reducing the installation space for the rotor 2. Furthermore, for example, the cylinder 10 of the rotor 2 can be insert-molded together with the metal body 5, making it easier to install multiple metal bodies 5 on the rotor 2.

[0037] As described above, the coil structure 7 has a cylindrical shape extending along the axis x, and each coil 20 is aligned along the axis x and faces in the radial direction. This allows the coils 20 to suppress the effects of movement of the stator 3 in the direction of the axis x. For example, the stiffness of the coils 20 against vibration of the stator 3 in the direction of the axis x is increased, thereby improving the detection accuracy of the angle sensor 1 and increasing the strength of the coils 20 against vibration of the stator 3 in the direction of the axis x. Furthermore, the coils 20 can be formed of magnet wire, eliminating the need for connections between the coils 20.

[0038] Furthermore, by making the width W1 of the metal body 5 in the axial x direction larger than the width W2 of the coil 20 in the axial x direction, the metal body 5 can be extended beyond the coil 20 in both directions along the axial x. As a result, even if relative movement occurs between the rotor 2 and the stator 3 in the axial x direction and the positional relationship between the rotor 2 and the stator 3 in the axial x direction deviates from the desired positional relationship, the entire width W2 of the coil 20 can face the metal body 5. Therefore, even if the positional relationship between the rotor 2 and the stator 3 in the axial x direction deviates from the desired positional relationship, the accuracy of the detected angle is not affected or the effect on the accuracy of the detected angle can be reduced. Furthermore, even if eccentricity occurs between the rotor 2 and the stator 3, the widening and narrowing of the radial spacing between the multiple metal bodies 5 and the coil structure 7 balance each other, so that in this case too, the accuracy of the detected angle is not affected or the effect on the accuracy of the detected angle can be reduced.

[0039] Furthermore, by embedding the metal body 5 in a resin member, the durability of the metal body 5 against oil and heat can be improved, and the metal body 5 can be prevented from scattering.

[0040] As described above, the coil structure 7 is formed by winding magnet wire around the multiple protrusions 34 that protrude outward from the outer circumferential surface 33a of the base 33 of the tube 30 of the stator 3, and the magnet wire is wound from the outer circumferential side so as to follow the outer circumferential surface 33a of the base 33. This makes it possible to reduce the radial gap between the coil structure 7 and the outer circumferential surface 33a of the base 33. This allows the coil structure 7 to be shaped to conform more closely to the outer circumferential surface 33a, that is, to conform to a cylindrical surface. This allows the coil structure 7 of the stator 3 to have a shape that is closer to the desired shape, thereby improving the detection accuracy of the angle sensor 1.

[0041] 8, in the case of the shape of the stator 3, the excitation circuit 38 and the stator coil structure pieces 7a, 7b can be arranged so as to overlap partially in the direction of the axis x, thereby improving the detection accuracy of the angle sensor 1. Also, since the excitation circuit 38 can be arranged closer to the rotor 2, the air gap between the excitation circuit 38 and the rotor 2 can be reduced. This allows the angle sensor 1 to be made smaller.

[0042] Furthermore, as described above, the coil structure 7 and the excitation circuit 38 can be protected without adding any member such as potting.

[0043] Furthermore, the frame 4, which is an attachment member for attaching the angle sensor 1 to an application object, is detachable from the stator 3 as described above. Therefore, by selecting a frame 4 that corresponds to the application object, the angle sensor 1 can be attached to various types of application objects. Furthermore, various electronic components (e.g., a communication device, a power generation device, a battery, etc.) other than the device used for detection may be provided on the frame 4 side. In this case, the frame 4 and the stator 3 may be electrically connected. Note that the various electronic components described above may be provided on the stator 3.

[0044] Furthermore, the cylinder 30 of the stator 3 is interposed between the coil structure 7 and the rotor 2 in the radial direction, which prevents the rotor 2 from coming into contact with the coil 20 .

[0045] Furthermore, since the frame 4 is located on the outer periphery of the stator 3, the width of the stator 3 and the frame 4 in the direction of the axis x in the assembled state is small. In this way, the width of the angle sensor 1 in the direction of the axis x can be reduced.

[0046] In the above-described embodiment, the stator 3 includes the cylinder 30, which is a cylindrical member, the frame 4 includes the cover 40, which is a cylindrical portion, and the member by which the stator 3 and the frame 4 are fixed to each other has a circumferentially continuous annular shape. However, the configuration of the stator 3 and the frame 4 is not limited to this. FIG. 14 is a perspective view showing a modified example of the stator 3 and the frame 4, and FIG. 15 is a perspective view showing a modified example of the stator 3. For example, as shown in FIG. 15 , the stator 3 may be arc-shaped and may extend only along a portion of the entire circumference of the stator 3 described above. The stator 3 according to the modified example is formed from the same material as the stator 3 described above. The stator 3 according to the modified example is formed, for example, from an insulating resin member. Similarly, the frame 4 according to the modified example may be arc-shaped and may extend only along a portion of the entire circumference of the frame 4 described above, as shown in FIG. 14 . The frame 4 according to the modified example is formed from the same material as the frame 4 described above. The frame 4 according to the modified example is formed, for example, from an insulating resin member. The following describes in detail the stator 3 and the frame 4 according to the modified example. Note that, with regard to the components of the stator 3 and the frame 4 according to the modified example, the same reference numerals are used for components that have the same configuration or similar functions as the stator 3 and the frame 4 described above, and descriptions thereof will be omitted.

[0047] As shown in FIG. 15 , the stator 3 according to the modified example specifically includes, for example, an arc-shaped or approximately arc-shaped portion (hereinafter referred to as an arc portion) 30A corresponding to a circumferential section of the tube 30, instead of the cylindrical tube 30. As shown in FIG. 15 , a plurality of protrusions 34 are formed in a row on the outer peripheral surface 33a of the arc portion 30A, similar to the stator 3 described above. The arc portion 30A has a plurality of protrusions 34 formed in a portion of the tube 30 corresponding to the arc portion 30A. The stator 3 according to the modified example is provided with a detection coil and an excitation circuit. The detection coil is formed by a plurality of coils 20, similar to the detection coil (coil structure 7) provided in the stator 3 described above. Specifically, the plurality of coils 20 are arranged so as to form the coil structure pieces 7a, 7b located in the portion of the tube 30 corresponding to the arc portion 30A. In the stator 3 according to the modified example, like the plurality of coils 20 in the above-described stator 3, the plurality of coils 20 are formed by winding a conductive member such as a magnet wire around the protruding portion 34. Like the above-described excitation circuit 38, the excitation circuit is a magnetic circuit that generates a periodically changing magnetic flux that acts on each of the plurality of coils 20 formed in the arc portion 30A.

[0048] 14, the frame 4 according to the modified example specifically has, for example, instead of the cylindrical cover 40, a portion (hereinafter referred to as an arc portion) 40A extending in an arc or approximately arc shape corresponding to a portion of the circumferential section of the cover 40. The arc portion 40A of the frame 4 according to the modified example extends in an arc or approximately arc shape corresponding to the arc portion 30A of the stator 3 according to the modified example.

[0049] Similarly to the frame 4 described above, the frame 4 according to the modified example also has mounting portions 44, which are portions that are attached to an external device as an application target. In the frame 4 according to the modified example, the mounting portions 44 are provided, for example, at two circumferential ends of the arc portion 40A. Furthermore, an electric circuit device having a circuit unit (not shown), such as a substrate 8 or an IC, and a calculation unit, is mounted or fixed to the frame 4 according to the modified example. Specifically, for example, the frame 4 according to the modified example has a holding portion 45 that accommodates the substrate 8 or the electric circuit device, similar to the frame 4 described above. The substrate 8 or the electric circuit device may be provided on one of the circumferential ends of the frame 4. In this case, a large area can be secured for providing the excitation circuit and the detection coil in the stator 3 according to the modified example, thereby contributing to improved detection accuracy. Furthermore, the substrate 8 or the electric circuit device may be adjacent to the excitation circuit or the detection coil in the circumferential direction. In other words, the substrate 8 or the electric circuit device is disposed circumferentially between the detection coil or the excitation circuit and the mounting portion 44. In this case, the limited space of the stator 3 and the frame 4 can be effectively utilized, which contributes to miniaturization of the angle sensor 1 .

[0050] Furthermore, in the above-described stator 3 and frame 4, as well as in the stator 3 according to the modified example and the frame 4 according to the modified example, the stator 3, frame 4, substrate 8, and electric circuit device may be sealed with an insulating resin member or the like. In this case, the resin can protect the stator 3, frame 4, substrate 8, and electric circuit device from foreign matter and the like.

[0051] Furthermore, the stator 3 or frame 4 described above, as well as the stator 3 according to the modified example or the frame 4 according to the modified example, may be provided with a connector that can be electrically connected to an external device. The connector may be provided adjacent to the substrate 8 or the electric circuit device. In this case, the substrate 8 or the electric circuit device and the connector can be connected via the shortest path, which contributes to miniaturization of the angle sensor 1.

[0052] Although the present invention has been described above through the above embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments. It will be apparent to those skilled in the art that various modifications and improvements can be made to the above embodiments. It is clear from the claims that such modifications and improvements can also be included within the technical scope of the present invention.

[0053] The above-described embodiments are intended to facilitate understanding of the present invention and are not intended to limit the scope of the present invention. Furthermore, the above-described embodiments do not limit the scope of the present invention, and the present invention may include any and all applications. The components of the above-described embodiments, as well as their arrangement, materials, conditions, shape, size, etc., are not limited to those illustrated and may be modified as appropriate. For example, the present invention includes differences that arise during implementation due to manufacturing tolerances, etc. Furthermore, components illustrated in different embodiments may be partially substituted or combined within the scope of technical inconsistency. Furthermore, the various configurations may be selectively combined as appropriate to achieve at least some of the above-described problems and effects.

[0054] 1 Angle sensor, 2 Rotor, 3 Stator, 4 Frame, 5 Metal body, 6 Metal body structure, 7 Coil structure, 7a, 7b Coil structure piece, 8 Substrate, 10 Cylinder, 11 Inner peripheral surface, 12 Outer peripheral surface, 13, 14 End surface, 20, 20a, 20b Coil, 30 Cylinder, 30A Arc portion, 31 Inner peripheral surface, 32 Outer peripheral surface, 33 Base portion, 33a Outer peripheral surface, 33b Side surface, 34 Protrusion portion, 35, 36 Flange portion, 35a, 36a End surface, 37 Step portion, 37a Step surface, 37b Recess, 38 Excitation circuit, 40 Cover, 40A Arc portion, 41 Inner peripheral surface, 42 Outer peripheral surface, 43 Flange portion, 44 Mounting portion, 44a Through hole, 45 Holding portion

Claims

1. An angle sensor comprising: a cylinder, a rotor having a number of metal bodies fixed to the cylinder, a stator, and a frame fixed to the stator, wherein the stator comprises a cylinder having an inner surface facing the rotor and an outer surface facing the frame, and a number of coils attached to the outer surface of the cylinder.

2. The angle sensor according to claim 1, wherein the outer surface of the cylinder is provided with a plurality of protrusions extending in the radial direction, and the plurality of coils are wound around the plurality of protrusions.

3. The angle sensor according to claim 1 or 2, wherein the conducting wire forming the coil extends along the outer surface of the cylinder.

4. The angle sensor according to claim 1, wherein the frame is provided with a cover that covers the plurality of coils.

5. The angle sensor according to any one of claims 1 to 4, wherein the frame has a mounting portion.

6. The angle sensor according to any one of claims 1 to 5, wherein the cylinder of the stator is made of resin.

7. The angle sensor according to any one of claims 1 to 6, wherein a substrate is attached to the frame, and one or more electronic components and one or more wirings are provided on the substrate.

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