JP2001004314A - Apparatus for detecting relative rotation angle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an apparatus for detecting a relative rotation angle which can be set to a shaft in a short time without a setting accuracy required and which has a superior detect characteristic. SOLUTION: An apparatus 10 for detecting a relative rotation angle has a first rotor 11 fixed in a predetermined position of a shaft axis direction, a second rotor 12 fixed to a shaft 5 to be adjacent to the first rotor, and a magnetic material core 13 with a resonant coil 13c arranged in the periphery of the first rotor for forming a magnetic circuit in cooperation with the first rotor. The first rotor is formed of a magnetic material of an insulator, and a non-uniform magnetic field is formed by the first rotor and the magnetic material core. The second rotor is provided with a conductor part which traverses an area of a different intensity of the non-uniform magnetic field in accordance with a relative rotation angle difference when the relative rotation angle difference is generated between a shaft position where the first rotor is fixed and a shaft position where the second rotor is fixed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a detecting device which is attached to a shaft which causes a relative rotation angle shift at different positions in the axial direction, and detects the relative rotation angle difference.

[0002]

2. Description of the Related Art For example, a relative rotation angle detecting device is sometimes used to detect a torque acting on a steering shaft of an automobile. This relative rotation angle detection device is a device that detects, as a rotation angle difference, a relative rotation of a shaft composed of a driving shaft, a passive shaft, and a torsion joint that connects the driven shaft and the passive shaft in accordance with torque.

More specifically, as shown in FIG. 13, a torque from a handle (not shown) is transmitted to a passive shaft 5c via a driving shaft 5a and a torsion joint 5b. Through the torsion joint 5b,
A relative rotation angle difference occurs between the driving shaft 5a and the passive shaft 5c in proportion to the magnitude of the torque. For example, a relative rotation angle difference between the two shafts, that is, a deviation amount of the rotation angle varies within a range of ± 8 degrees. If the deviation of the rotation angle between the two shafts can be accurately detected, it can be accurately converted to the torque acting on the shaft 5.

As an example of such a relative rotation angle detection device, a detection device 50 shown in FIG. 13 is known. This detection device 50 is located near the torsion joint 5b.
A fixed magnetic member 53 around which a resonance coil 53c is wound is provided, a cylindrical movable magnetic member 51 is fixed to the driving shaft 5a, and a cylindrical movable magnetic member 52 is fixed to the passive shaft 5c. I have. Also, the movable magnetic members 51, 5
Notch portions (not shown) are formed at equal intervals around the periphery of the two opposing end surfaces. With this configuration,
The area of the portions of the end surfaces of the movable magnetic members 51 and 52 that are close to each other is changed in proportion to the amount of rotation angle deviation generated between the two shafts, thereby changing the effective relative magnetic permeability of the magnetic circuit and changing the inductance of the coil. Is changed to detect the deviation of the rotation angle between the movable magnetic members 51 and 52, that is, between the two shafts.

[0005]

When an alternating current is applied to the resonance coil in the above-described device, a magnetic circuit is formed as shown by a dotted line in FIG. When the relative magnetic permeability of the magnetic material is considerably high, the magnetic resistance in this magnetic circuit is represented by G shown in FIG.
It is determined by the magnetic resistance of three gaps of 1, G2 and G3. Since the effective relative permeability of the magnetic circuit is inversely proportional to the total magnetic resistance of the magnetic circuit, and the inductance L of the coil is proportional to the effective relative permeability of the magnetic circuit, the gaps G1, G2, and G3 are not constant. Then, it is apparent that the effective relative permeability of the magnetic circuit changes, and the inductance L of the coil also does not become constant.

Here, the movable magnetic members 51 and 52 have a cylindrical shape, and the fixed magnetic member 53 also has a cylindrical shape having an inner diameter larger than the outer diameter of the movable magnetic members 51 and 52. An air gap is formed between 53 and the movable magnetic members 51 and 52. If the degree of concentricity between the fixed magnetic member 53 and the movable magnetic members 51 and 52 is high, the gap of the air gap between the fixed magnetic member and the movable magnetic member is always constant in the circumferential direction of each member. If the concentricity of the movable magnetic members 51 and 52 is low, the interval of the air gap will not be constant in the circumferential direction. However, since the air gap always becomes the maximum at the point where the gap of the air gap is the minimum and the point on the opposite side in the circumferential direction,
The air gap as a whole can be regarded as constant, so that the variation in the gaps G2 and G3 does not significantly affect the change in the effective relative magnetic permeability of the magnetic circuit.

On the other hand, if the distance between the movable magnetic members 51 and 52 is not constant, the gap G1 will not be constant, and the gap G1 will not be constant.
The variation of 1 significantly affects the change in the effective relative permeability of the magnetic circuit. Therefore, accurate management of the gap G1 is important in preventing unnecessary change in the effective relative magnetic permeability of the magnetic circuit. However, in general, the detection device 50
In the case of retrofitting to the shaft 5, it is difficult to assemble while accurately managing the gap G1 due to assembling accuracy and the like. Therefore, it is actually required to attach the detection device 50 to the object to be mounted together with the shaft in a state in which the detection device 50 is assembled in the shaft 5 in advance, and thus there is a problem that an assembly cost is increased and the assembly process is restricted. When the torsion joint 5b of the shaft 5 undergoes thermal expansion or thermal contraction, the gap G1 changes accordingly, and the effective relative magnetic permeability of the magnetic circuit unnecessarily changes regardless of the relative rotation of the rotor. There is also a problem.

On the other hand, Japanese Patent Publication No. 63-55528 discloses a cylindrical shape as shown in FIG.
A notch is formed at a predetermined position in the longitudinal direction of the two conductive members, and the shaft to which the conductive member is attached relatively rotates to change the area of the conductive member that crosses the magnetic field, thereby causing a vortex in the conductive member. A configuration is disclosed in which a current is generated, and the inductance of the coil is changed thereby to detect a shift amount of the shaft relative rotation angle.

According to this configuration, since the area of the conductive member that crosses the magnetic field is changed by the relative position change of the two conductive members, in order to accurately detect the deviation of the shaft rotation angle, It is necessary to make the amount of deviation between the rotation angles of both shafts and the magnitude of the eddy current generated in the conductive member proportional. In terms of structure, the area of the conductor member crossing the magnetic field is proportional to the amount of the deviation, but it is necessary to keep the strength of the magnetic field crossing both conductor members constant. However, the magnetic field generated from the coil is distributed almost uniformly in the circumferential direction, but the magnetic field distribution in the direction of the rotation axis or in the radial direction of the coil is not uniform. Therefore, in order to secure sensing rich in linear characteristics, it is necessary to assemble two conductive members so as to overlap each other without any gap.
There is still a problem that the assembling precision is strictly required to improve the detection characteristic of the shaft rotation angle.

An object of the present invention is to provide a relative rotation angle detecting device which can easily assemble a detecting device on a shaft without requiring assembling accuracy and has excellent detecting characteristics.

[0011]

To achieve the above object, a relative rotation angle detecting device according to the present invention comprises a first rotor fixed at a predetermined position in the axial direction of a shaft;
A second rotor fixed to a shaft adjacent to the first rotor, a magnetic material core disposed around the first rotor and having a resonance coil forming a magnetic circuit in cooperation with the first rotor; Wherein the first rotor is formed of a magnetic material made of an insulator, forms a non-uniform magnetic field between the first rotor and the magnetic material core, and the second rotor is fixed to the first rotor. When a relative rotation angle difference is generated between the shaft position to be fixed and the shaft position to which the second rotor is fixed, a conductor portion that crosses regions having different strengths of the non-uniform magnetic field according to the rotation angle difference It is characterized by having.

[0012] The area where the conductor of the second rotor crosses the region where the strength of the non-uniform magnetic field formed by the first rotor and the magnetic material core disposed around the first rotor is different is fixed to the first rotor. Since the relative rotation angle difference is detected based on a change in the relative rotation angle difference generated between the set shaft position and the fixed shaft position of the second rotor, the first rotation
The relative rotation angle of the shaft can be detected without strictly requiring the mounting position accuracy of the first rotor and the second rotor in the axial direction of the shaft.

Since the first rotor is made of a magnetic material made of an insulator, no eddy current is generated in the first rotor. Therefore, the magnitude of the eddy current generated when the relative rotation angle difference of the shaft and the conductor portion of the second rotor cross the region where the strength of the non-uniform magnetic field is different is proportional, and the linear characteristic of the detection output is excellent. Therefore, it is not necessary to strictly manage the radial gap between the first rotor and the second rotor, and the assemblability of the detector to the shaft is improved.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A description will now be given, with reference to the drawings, of a relative rotation angle detecting device according to a first embodiment of the present invention. As shown in FIGS. 1 and 2, a relative rotation angle detecting device 10 according to a first embodiment of the present invention includes a first rotor 11, a second rotor 12, and a magnetic material core 13 (only in FIG. 1). This is attached to a shaft 5 composed of a driving shaft 5a, a passive shaft 5c, and a torsion joint 5b which connects them and increases the torsion according to the torque.

The first rotor 11 has a bottomed cylindrical shape,
It is configured to be fixed to the passive shaft 5c with a fastener such as an adhesive or a screw. The second rotor 12 also has a bottomed cylindrical shape having an inner diameter larger than the outer diameter of the first rotor 11, and is fixed to the driving shaft 5a with a fastener such as an adhesive or a screw. Around the second rotor 12, a magnetic core 13 is fixed to a non-rotating structure via a non-magnetic bracket (not shown).

Therefore, the peripheral portion of the second rotor 12 is
Is located in a ring-shaped gap formed between the rotor 11 and the magnetic material core 13. First rotor 11
Is a soft magnetic member obtained by mixing, for example, Ni-Zn or Mn-Zn soft magnetic powder at a fixed ratio with an insulating molding material such as nylon, polypropylene (PP), polyphenylene sulfide (PPS), and ABS resin. And has thermoplasticity, low cost, and excellent vibration resistance.
FIG. 2 is a perspective view of an outer peripheral portion of the first rotor 11.
As is clear from FIG. 5, which is shown in an unfolded state, six notches 11a are formed at equal intervals in the circumferential direction, and six teeth 11b are formed at equal intervals between the notches. By adopting such a configuration, as shown in FIG. 3, a region A having a large magnetic flux density is formed between the magnetic material core 13 and the teeth 11b of the first rotor, and the magnetic material core 13 and the first rotor A region B having a small magnetic flux density is formed between the notch 11a of the rotor and the notch 11a. That is, a non-uniform magnetic field is formed between the first rotor 11 and the magnetic material core 13. When the passive shaft 5c to which the first rotor 11 is fixed rotates, the non-uniform magnetic field also rotates accordingly.

The magnetic material core 13 has a resonance coil 13c formed on the inner peripheral surface side of a cylindrical body made of the same soft magnetic member as the first rotor 11 to form a magnetic circuit in cooperation with the first rotor 11. Is wound. The second rotor 12 is made of a conductive member such as aluminum, for example, and forms a conductor as a whole. Further, as shown in FIG. 2 which is a perspective view and FIG. 5 which shows the outer peripheral part in an expanded state, six notches 12a similar to the first rotor 11 are formed at equal intervals in the outer peripheral part thereof. Six teeth 12b are formed at equal intervals between each notch.

Therefore, as shown in FIGS. 5A and 6A, when the teeth 11b of the first rotor and the teeth 12b of the second rotor completely face each other, the second rotor 12 The magnetic flux density in the magnetic field region traversing the magnetic circuit formed between the magnetic material core 13 and the teeth 11b of the first rotor is highest, and thus the eddy current generated in the second rotor 12 is also highest.

As shown in FIGS. 5 (b) and 6 (b), when the teeth 11b of the first rotor and the teeth 12b of the second rotor partially face each other, the second rotor 12 The magnetic flux density in the magnetic field region traversing the magnetic circuit is moderate, and
The eddy current generated in the rotor 12 becomes medium. Furthermore,
As shown in FIG. 5 (c) and FIG. 6 (c), the tooth 1 of the first rotor
When the teeth 1b and the teeth 12b of the second rotor do not face each other at all, the magnetic flux density in the magnetic field region where the second rotor 12 traverses the magnetic circuit is the weakest.
The eddy current generated at the time is also minimized.

The relative rotation of the driving shaft 5a and the passive shaft 5c causes the first rotor teeth 11b and the second rotor teeth 11b to rotate.
5 (a) (FIG. 6 (a)) through FIG. 5 (c).
(See FIG. 6 (c)). In response to this, the magnitude of the eddy current generated in the second rotor 12, which is a conductor, changes periodically as described above. The relative rotation angle difference between the first rotor 11 and the second rotor 12 is calculated using the change in coil impedance caused by the change in eddy current.
Consequently, the relative rotation angle difference between the passive shaft 5c and the driving shaft 5a can be easily detected.

Specifically, as shown in FIG. 7, the resonance coil 13c is electrically connected so as to be subjected to f / V conversion via an oscillation circuit, and the coil L and a capacitor (shown in FIG. 1). the resonance frequency f ₀ = 1 / (2π obtained from the C of not)
(LC) ^1/2 ). As described above, the magnitude of the eddy current generated in the second rotor 12 changes due to the relative rotation between the first rotor 11 and the second rotor 12, thereby changing the coil impedance of the coil 13c. The resonance frequency f _{0 of the} resonance circuit changes.
By detecting this f ₀ by the signal processing circuit, the first
Rotor 11 (passive shaft 5c) and second rotor 12
The relative rotation angle difference of the (drive shaft 5a) can be measured.

As described above, according to the structure of the relative rotation angle detecting device 10 according to the present invention, like the conventional relative rotation angle detecting device 50 shown in FIG. G1 does not have to be formed. Further, since the first rotor 11 is formed of a magnetic material made of an insulator, the first rotor 11 and the second rotor 1
2 does not strictly require the relative mounting position accuracy, the relative rotation angle difference between the first rotor 11 and the second rotor 12 and the conductor of the second rotor 12 The amount of change in the area crossing the regions having different intensities is always in a proportional relationship, and the linear characteristic of the detection output is excellent.

More specifically, in the relative rotation angle detecting device 10 according to the present invention, the soft magnetic member is the first rotor 11
And the magnetic material core 13 only, they are attached without strictly maintaining the concentricity of the two. Even if the gap between the outer peripheral surface of the first rotor 11 and the inner peripheral surface of the magnetic material core 13 becomes uneven, The difference in the magnetic resistance is canceled over the entire circumferential direction, and as a result, the magnetic resistance substantially matches the sum of the magnetic resistances when both are mounted with the concentricity strictly maintained. That is, since the gap is formed in a ring shape, the total magnetic resistance is constant without being affected by the fluctuation of the concentricity between the shaft and the coil, the deflection of the rotation center axis, and the like, and the detection error can be suppressed to a small value. .

Also, since the first rotor 11 is formed of a magnetic material made of an insulator, no eddy current is generated in the first rotor 11. Therefore, the relative rotation angle difference of the shaft 5 and the magnitude of the eddy current generated when the conductor of the second rotor 12 crosses the area where the strength of the non-uniform magnetic field is different are proportional, and the linear characteristic of the detection output is reduced. Excellent. That is, the coil 13
Since the eddy current affecting the impedance of c is generated only in the second rotor 12, the sensitivity and linearity of the detection device can be improved.

Therefore, in performing relative rotation angle detection with excellent linear characteristics, a gap between rotors can be allowed up to several mm order without requiring a gap between rotors up to several μ order. Therefore, for example, when assembling the relative rotation angle detection device according to the present invention to a steering device of an automobile required to be mass-produced, the assembly cost is reduced by allowing the gap between the rotors to several mm order as described above. Greatly contribute to. Further, the relative rotation angle detecting device can be assembled even in an automobile assembly line, so that there is no need to restrict the assembly process.

Further, since the first rotor 11 and the magnetic material core 13 are made of a magnetic material having an insulating property, the manufacturing cost can be reduced. Incidentally, in the embodiment described above, as shown in FIG. 4, the axial overall length L _A of the magnetic material core 13, the axial overall length L _B of the first rotor 11, the axial total length L _C of the second rotor 12 Between L _B > L _A , L _C
> Preferably has a dimensional relationship of L _A. This makes it possible to loosen the mounting accuracy of the first rotor 11, the second rotor 12, and the magnetic material core 13 in the axial direction, and to facilitate the assembling of the detection device.

In the case of the first embodiment, as the number of teeth on the circumference increases, the same detection output is obtained repeatedly. Therefore, the range of the relative rotation angle difference that can be detected is narrowed, but the detection sensitivity is increased. . Specifically, in the case of the first embodiment, the six teeth and the six notches have a uniform size and each occupy an angular range of 1/12 (30 degrees) of 360 degrees. Therefore, the maximum detectable relative rotation angle deviation amount is ± 15 degrees.
That is, the same detection output is repeatedly obtained every time the two rotors rotate by 30 degrees in the relative rotation.

Therefore, the relative rotation angle detecting device 10 of the first embodiment needs to detect the deviation of the relative rotation angle with high accuracy although the deviation of the relative rotation angle of the shaft 5 is as small as ± 8 degrees, for example. In this case, for example, it is suitably used for torque detection of the shaft 5 and the like. Note that, unlike the above-described embodiment, the second rotor 12 is made of only a conductor such as aluminum.
8, the second rotor 15 may be formed by attaching a conductor 15b such as aluminum to a part of a moldable resin material 15a, as shown in FIG. If the conductor portion 15b of the second rotor gradually crosses the magnetic field formed by the first rotor 11 and the magnetic material core 13 in accordance with the relative rotation of the shaft 5, the rotation of the above-described embodiment is achieved. As in the case of the angle detection device 10, the amount of deviation of the rotation angle of the shaft 5 can be accurately detected.

Next, a rotation angle detecting device according to a second embodiment of the present invention will be described. In addition, about the structure equivalent to the rotation angle detection apparatus 10 which concerns on 1st Embodiment, a corresponding code | symbol is attached | subjected and detailed description is abbreviate | omitted. As shown in FIG. 9, the rotation angle detection device 20 according to the second embodiment includes a driving shaft 5a, a passive shaft 5c, and a torsion joint 5b, like the rotation angle detection device 10 according to the first embodiment. The first rotor 21 made of the above-described insulating soft magnetic member is fixed to the passive shaft 5c, and is attached to the passive shaft 5c.
In a, the whole is made of a conductor such as aluminum,
A second rotor having an inner diameter larger than the outer diameter of the first rotor 21;
Are fixed. Also, the first rotor 21
A magnetic material core (not shown in FIG. 9) 23 is disposed around the periphery of the magnetic material.

The magnetic material core 23 has the same configuration as the magnetic material core 13 of the first embodiment, except that the first rotor 21 and the second rotor 22 have the same configuration as the first embodiment. Instead of having six teeth and notches respectively, semi-circular continuous notches 21a, 22a and teeth 21b, 22b
Are different from each other in that they have With such a configuration, as shown in FIG. 10, the space C between the semicircular teeth 21 b of the first rotor 21 in the end view and the magnetic material core 23 becomes a region where the magnetic flux density is large, and the first rotor 21 2
The space D between the notch 21a and the magnetic material core 23, which is a semi-circular notch 21 in end view, is a region where the magnetic flux density is small. As a result, a non-uniform magnetic field is formed in the circumferential direction.

Since the conductor of the second rotor 22 which crosses the regions having different intensities of the non-uniform magnetic field also has the teeth 22b having a semi-circular shape in end view as shown in FIG.
And the magnitude of the eddy current generated in the conductor of the second rotor 22 has a proportional relationship over a wide range. In the case of the second embodiment,
Since the relative rotation angles of the two rotors 21 and 22 can be continuously measured, the present invention is suitably used, for example, for detecting a steering angle of a steering wheel of an automobile.

Specifically, in order to detect a deviation of the relative rotation angle over a range of 360 degrees, two rotors 21 and
22 are formed in a semi-circular shape in end view as described above, and FIG.
As shown in FIG. 1 and FIG. 12, the first rotor 21 and the magnetic material core 2
3, the teeth 22b of the second rotor gradually cross the magnetic circuit, and an eddy current is generated in proportion to the amount of change in the area of the second rotor 22 which crosses the magnetic circuit. By changing the coil impedance, it is possible to detect the deviation of the rotation angle over a wide range with excellent linear characteristics, and it is possible to accurately detect the steering angle of the shaft 5.

When it is necessary to determine the rotation angle direction of the relative rotation of the shaft, an absolute position sensor may be additionally provided in the detection device. For example, a commercially available photosensor is attached to an appropriate position of the first rotor or the second rotor, the output of the photosensor is turned on when the relative rotation angle is 0 to 180 degrees, and the relative rotation angle is 180 to 360 degrees. If the output of the photo sensor is turned off in degrees, the relative rotation angle direction of the shaft can be determined at the same time.

[0034]

As described above, in the relative rotation angle detecting device according to the present invention, the magnetic circuit formed by the first rotor and the magnetic material core disposed around the first rotor is formed by the second rotor. The relative rotation angle difference is detected based on the fact that the area traversed by the conductor changes according to the relative rotation angle difference generated between the fixed shaft position of the first rotor and the fixed shaft position of the second rotor. Therefore, the relative rotation angle of the shaft can be detected without strictly requiring the mounting position accuracy of the first rotor and the second rotor in the axial direction of the shaft.

Further, since the first rotor is formed of a magnetic material made of an insulator, no eddy current is generated in the first rotor. Therefore, the magnitude of the eddy current generated when the relative rotation angle difference of the shaft and the conductor portion of the second rotor cross the region where the strength of the non-uniform magnetic field is different is proportional, and the linear characteristic of the detection output is excellent. Therefore, it is not necessary to strictly manage the radial gap between the first rotor and the second rotor, and the assemblability of the detector to the shaft is improved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view schematically showing a relative rotation angle detecting device 10 according to a first embodiment of the present invention mounted on a shaft 5. FIG.

FIG. 2 is a perspective view schematically showing the relative rotation angle detection device 10 of FIG. 1 except for a magnetic material core 13;

3 is a diagram showing the magnitude of the magnetic flux density in the relative rotation angle detection device 10 of FIG. 1 as viewed from an end face.

FIG. 4 is a partial cross-sectional view showing a magnetic circuit formed in the relative rotation angle detection device 10 of FIG.

FIG. 5 shows a first example of the relative rotation angle detecting device 10 of FIG.
FIG. 4 is a view showing outer peripheral portions of a rotor 11 and a second rotor 12 in a developed state.

FIG. 6 is a diagram showing a relation between a state where the first rotor 11 and the second rotor 12 are relatively rotated and a magnetic flux density in FIG.

FIG. 7 is a circuit block diagram illustrating a connection relationship between a coil 13c and a signal processing circuit in FIG. 1;

FIG. 8 is a partial sectional view showing a modification of the relative rotation angle detection device 10 of FIG.

FIG. 9 is a perspective view schematically showing a relative rotation angle detecting device 20 according to a second embodiment of the present invention, excluding a magnetic material core 23.

10 is a diagram showing the relative rotation angle detection device 20 of FIG. 9 in an end view.

FIG. 11 shows a first rotor 21 and a second rotor 22 shown in FIG. 9;
FIG. 7 is a diagram showing a relationship between a state in which the magnetic flux density is relatively rotated and a magnetic flux density in an end view.

FIG. 12 shows a first rotor 21 and a second rotor 22 shown in FIG. 9;
FIG. 12 is a view different from FIG. 11, showing a relationship between a state in which the magnetic flux density is relatively rotated and the magnetic flux density in an end view.

FIG. 13 is a schematic sectional view showing a conventional relative rotation angle detection device 50.

FIG. 14 is a partial cross-sectional view showing a magnetic circuit formed in a conventional relative rotation angle detection device 50.

[Explanation of symbols]

 5a Main shaft 5b Torsion joint 5c Passive shaft 11 First rotor 11a Notch 11b Tooth 12 Second rotor 12a Notch 12b Tooth 13 Magnetic core 13c Coil 21 First rotor 21a Notch 21b Tooth 22 Second rotor 22a Notch 22b Tooth 23 Magnetic core 23c Coil

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Kengo Tanaka 2-6-1 Marunouchi, Chiyoda-ku, Tokyo Furukawa Electric Co., Ltd. F-term (reference) 2F063 AA34 AA35 BA08 BC04 CB12 DA01 DD03 GA07 GA08 GA29 GA50 GA69 KA01 KA05 LA05 ZA01 2F077 AA47 AA49 FF02 FF13 FF31 NN04 NN21 TT02 VV21

Claims (1)

[Claims] A first rotor fixed to a predetermined position in an axial direction of a shaft; a second rotor fixed to the shaft adjacent to the first rotor; and a first rotor fixed to a periphery of the first rotor. And a magnetic material core having a resonance coil forming a magnetic circuit in cooperation with the first rotor, wherein the first rotor is made of an insulating material. And a non-uniform magnetic field is formed between the first rotor and the magnetic material core, and the second rotor is fixed to a shaft position where the first rotor is fixed and the second rotor. When a relative rotation angle difference is generated between a fixed shaft position and a fixed shaft position, a conductor portion crossing regions having different intensities of the non-uniform magnetic field according to the rotation angle difference is provided. Rotation angle detection device.