Shaft for magnetic torque angle sensor

Abstract

The purpose of the present invention is to obtain a shaft for a magnetic torque angle sensor in which the axial dimension of the shaft can be reduced. This shaft for a magnetic torque angle sensor comprises an angle detection rotor and a torque detection rotor that is provided adjacent to the angle detection rotor in the axial direction, the angle detection rotor having an angle detection non-magnetic body part that is formed with a cylindrical outer peripheral surface and composed of a non-magnetic body, and an angle detection magnetic body part provided on the outer peripheral surface of the angle detection non-magnetic body part and composed of a magnetic body, the torque detection rotor having a torque detection magnetic body part formed integrally with the angle detection magnetic body part and composed of a magnetic body, and the axial size of the angle detection magnetic body part changing periodically in accordance with a change in circumferential position.

Description

Magnetic torque angle sensor shaft

[0001] The present invention relates to a shaft of a magnetic torque angle sensor.

[0002] Conventionally, a torque angle sensor including an angle sensor and a torque sensor has been known. The angle sensor and the torque sensor are arranged axially spaced apart from each other. The angle sensor is composed of an optical rotary encoder. The angle sensor has a light-emitting diode, a photodiode, and a rotating plate with slits. The light-emitting diode, the photodiode, and the rotating plate with slits are arranged axially spaced apart from each other. The rotating plate with slits is attached to a shaft. The torque sensor is composed of a non-contact magnetostrictive torque sensor. The torque sensor has a magnetic body and a magnetic sensor (see, for example, Patent Document 1).

[0003] JP 2008-76066 A

[0004] However, in the configuration of the torque angle sensor described in Patent Document 1, the angle sensor and the torque sensor are arranged at intervals in the axial direction. Also, in the configuration of the torque angle sensor described in Patent Document 1, the light-emitting diode, the photodiode, and the rotating plate with slits are arranged at intervals in the axial direction. This causes a problem in that the axial dimension of the torque angle sensor becomes large.

[0005] The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a shaft of a magnetic torque angle sensor that can reduce the axial dimension.

[0006] The magnetic torque angle sensor according to the present invention includes a shaft including an angle-detecting rotor and a torque-detecting rotor axially adjacent to the angle-detecting rotor. The angle-detecting rotor has a cylindrical outer peripheral surface and a non-magnetic portion, and an angle-detecting magnetic portion formed on the outer peripheral surface of the non-magnetic portion and made of a magnetic material. The torque-detecting rotor has a magnetic portion integral with the angle-detecting magnetic portion and made of a magnetic material, the axial size of the magnetic portion changing periodically with change in circumferential position. The angle-detecting rotor has a cylindrical angle-detecting central portion, and the non-magnetic portion is ring-shaped and attached to the outer peripheral surface of the angle-detecting central portion. The angle-detecting non-magnetic portion is also cylindrical. In the shaft of the magnetic torque angle sensor according to the present invention, the torque detecting rotor has a torque detecting non-magnetic portion made of a non-magnetic material and having a cylindrical outer circumferential surface, and the torque detecting magnetic portion is provided on the outer circumferential surface of the torque detecting non-magnetic portion. In the shaft of the magnetic torque angle sensor according to the present invention, the torque detecting non-magnetic portion is formed in a cylindrical shape. In the shaft of the magnetic torque angle sensor according to the present invention, the torque detecting rotor has a torque detecting core portion formed in a cylindrical shape, and the torque detecting non-magnetic portion is formed in a ring shape and is provided on the outer circumferential surface of the torque detecting core portion.

[0007] The shaft of the magnetic torque angle sensor according to the present invention can reduce the axial dimension.

[0008] FIG. 1 is a front view of a magnetic torque angle sensor including a shaft of the magnetic torque angle sensor according to a first embodiment. FIG. 2 is a cross-sectional view showing a main part of the magnetic torque angle sensor of FIG. 1. FIG. 3 is a front view of the shaft of the magnetic torque angle sensor of FIG. 1. FIG. 4 is a front view of a main part of the shaft of the magnetic torque angle sensor of FIG. 3. FIG. 5 is a cross-sectional view taken along line V-V of FIG. 3. FIG. 6 is a cross-sectional view taken along line VI-VI of FIG. 3. FIG. 7 is a perspective view of the fixed body of FIG. 1. FIG. 8 is a cross-sectional view of the fixed body of FIG. 7. FIG. 9 is a cross-sectional view of an angle-detecting rotor in a shaft of a magnetic torque angle sensor according to a second embodiment. FIG. 10 is a cross-sectional view of a torque-detecting rotor in a shaft of a magnetic torque angle sensor according to a third embodiment.

[0009] Embodiment 1 Fig. 1 is a front view showing a magnetic torque angle sensor having a shaft of the magnetic torque angle sensor according to embodiment 1. Fig. 2 is a cross-sectional view showing a main part of the magnetic torque angle sensor of Fig. 1.

[0010] The magnetic torque angle sensor includes a shaft 1 and a magnetic pole portion 2 .

[0011] The direction along the axis of shaft 1 is defined as the axial direction. The direction along the radius of a circle centered on the axis of shaft 1 in a plane perpendicular to the axis of shaft 1 is defined as the radial direction. The direction along the circumference of a circle centered on the axis of shaft 1 in a plane perpendicular to the axis of shaft 1 is defined as the circumferential direction.

[0012] The magnetic pole portion 2 is formed in an annular shape. The shaft 1 is disposed so as to face the magnetic pole portion 2 in the radial direction. The shaft 1 is rotatable in the circumferential direction around the axis of the shaft 1 at the center of the magnetic pole portion 2. A bearing (not shown) is provided between the shaft 1 and the magnetic pole portion 2.

[0013] Fig. 3 is a front view showing the shaft 1 of the magnetic torque angle sensor of Fig. 1. Fig. 4 is a front view showing a main part of the shaft 1 of the magnetic torque angle sensor of Fig. 3. Fig. 5 is a cross-sectional view taken along line V-V in Fig. 3. Fig. 6 is a cross-sectional view taken along line VI-VI in Fig. 3.

[0014] The shaft 1 of the magnetic torque angle sensor according to the first embodiment includes a first shaft member 3 , an angle-detecting rotor 4 , a torque-detecting rotor 5 , and a second shaft member 6 .

[0015] The first shaft member 3, the angle detection rotor 4, the torque detection rotor 5 and the second shaft member 6 are arranged in the axial direction in the order of the first shaft member 3, the angle detection rotor 4, the torque detection rotor 5, and the second shaft member 6.

[0016] The first shaft member 3 is formed in a cylindrical shape and is disposed so as to extend in the axial direction.

[0017] The angle detection rotor 4 has an angle detection central portion 401 , an angle detection non-magnetic portion 402 , and an angle detection magnetic portion 403 .

[0018] The angle detecting central portion 401 is formed in a cylindrical shape. The angle detecting central portion 401 is disposed so as to extend in the axial direction. The angle detecting central portion 401 is connected to the first shaft member 3.

[0019] The angle detection non-magnetic material portion 402 is formed in a ring shape. The angle detection non-magnetic material portion 402 is provided on the outer peripheral surface 404 of the angle detection central portion 401. The angle detection non-magnetic material portion 402 has a cylindrical outer peripheral surface 405. The angle detection non-magnetic material portion 402 is made of a non-magnetic material. Methods for providing the angle detection non-magnetic material portion 402 on the outer peripheral surface 404 of the angle detection central portion 401 include coating, thermal spraying, and press fitting, for example.

[0020] The angle detection magnetic material portion 403 is provided on the outer peripheral surface 405 of the angle detection non-magnetic material portion 402. The angle detection magnetic material portion 403 is made of a magnetic material. Methods for providing the angle detection magnetic material portion 403 on the outer peripheral surface 405 of the angle detection non-magnetic material portion 402 include coating, thermal spraying, and press-fitting, for example.

[0021] The size of the angle detection magnetic material portion 403 in the axial direction changes periodically in accordance with the change in the circumferential position.

[0022] The torque detecting rotor 5 has a torque detecting central portion 501 and a torque detecting magnetic portion 502 .

[0023] The torque detection central portion 501 is formed in a cylindrical shape. The torque detection central portion 501 is disposed so as to extend in the axial direction. The torque detection central portion 501 is connected to the angle detection central portion 401.

[0024] The torque detection magnetic material portion 502 is provided on the outer peripheral surface 503 of the torque detection central portion 501. The torque detection magnetic material portion 502 is made of a magnetic material. Methods for providing the torque detection magnetic material portion 502 on the outer peripheral surface 503 of the torque detection central portion 501 include, for example, coating, spray forming, and press fitting.

[0025] The torque-detecting magnetic body portion 502 is formed integrally with the angle-detecting magnetic body portion 403. In other words, the angle-detecting magnetic body portion 403 and the torque-detecting magnetic body portion 502 are made of the same material and are formed integrally as a single member that cannot be disassembled. The angle-detecting magnetic body portion 403 and the torque-detecting magnetic body portion 502 are omitted from FIG. 4 .

[0026] The axial size of the torque detection magnetic material portion 502 does not change with changes in circumferential position, i.e., the axial size of the torque detection magnetic material portion 502 is constant regardless of changes in circumferential position.

[0027] The second shaft member 6 is formed in a cylindrical shape. The second shaft member 6 is disposed so as to extend in the axial direction. The second shaft member 6 is connected to the torque detection central portion 501.

[0028] The first shaft member 3, the angle detecting central portion 401, the torque detecting central portion 501, and the second shaft member 6 are integrally formed with one another. In other words, the first shaft member 3, the angle detecting central portion 401, the torque detecting central portion 501, and the second shaft member 6 are made of the same material and are a single, integrally formed member that cannot be disassembled. The first shaft member 3, the angle detecting central portion 401, the torque detecting central portion 501, and the second shaft member 6 are made of a material that is, for example, an alloy suited to the application of the shaft 1. An example of an alloy suited to the application of the shaft 1 is a structural alloy steel.

[0029] One of the first shaft member 3 and the second shaft member 6 is connected to a transmitted shaft (not shown), and the other is connected to a transmitting shaft (not shown) that is connected to a driving device (not shown).

[0030] Fig. 7 is a perspective view showing the magnetic pole portion 2 of Fig. 1. Fig. 8 is a cross-sectional view showing the magnetic pole portion 2 of Fig. 7. The magnetic pole portion 2 includes an angle-detecting stator 7 and a torque-detecting stator 8.

[0031] The angle-detecting stator 7 has an angle-detecting stator core 701 and a plurality of angle-detecting coils 702. The angle-detecting stator core 701 has an annular yoke portion 703 and a plurality of teeth portions 704.

[0032] The plurality of teeth 704 are arranged in a line in the circumferential direction, and each tooth 704 is arranged to extend radially inward from the yoke portion 703. Each of the plurality of teeth 704 is provided with one of the plurality of angle detection coils 702.

[0033] The torque detecting stator 8 has a torque detecting stator core 801 and a plurality of torque detecting coils 802. The torque detecting stator core 801 has an annular yoke portion 803 and a plurality of teeth portions 804.

[0034] The plurality of teeth 804 are arranged in a line in the circumferential direction, and each tooth 804 is arranged to extend radially inward from the yoke portion 803. Each of the plurality of teeth 804 is provided with a plurality of torque detection coils 802.

[0035] Next, a method of angle detection using the magnetic torque angle sensor will be described. The angle detection rotor 4 and the angle detection stator 7 are disposed radially opposite each other.

[0036] Each of the plurality of angle detection coils 702 includes an excitation coil and an angle detection coil. The excitation coil magnetizes the angle detection magnetic material portion 403 of the angle detection rotor 4. The gap permeance between the angle detection magnetic material portion 403 and the angle detection coil changes in accordance with the angle of the angle detection rotor 4.

[0037] The magnetic torque angle sensor detects the angle of the angle detecting rotor 4 by using a change in gap permeance between the angle detecting magnetic part 403 and the angle detecting coil.

[0038] Next, a method of torque detection using the magnetic torque angle sensor will be described. The torque detection rotor 5 and the torque detection stator 8 are disposed radially opposite each other.

[0039] The impedance of each of the plurality of torque detection coils 802 changes in response to the torque acting on the torque detection rotor 5 .

[0040] The magnetic torque angle sensor detects the torque acting on the torque detecting rotor 5 by using the change in impedance of each of the multiple torque detecting coils 802 .

[0041] As described above, the shaft 1 of the magnetic torque angle sensor according to the first embodiment includes the angle-detecting rotor 4 and the torque-detecting rotor 5, which is axially adjacent to the angle-detecting rotor 4. The angle-detecting rotor 4 has a cylindrical outer peripheral surface 405 and includes an angle-detecting non-magnetic material portion 402 made of a non-magnetic material, and an angle-detecting magnetic material portion 403 made of a magnetic material and disposed on the outer peripheral surface 405 of the angle-detecting non-magnetic material portion 402. The torque-detecting rotor 5 includes a torque-detecting magnetic material portion 502 made of a magnetic material and integrally formed with the angle-detecting magnetic material portion 403. The axial size of the angle-detecting magnetic material portion 403 periodically changes in response to changes in its circumferential position. With this configuration, the torque-detecting rotor 5 is axially adjacent to the angle-detecting rotor 4, and the torque-detecting magnetic material portion 502 is integrally formed with the angle-detecting magnetic material portion 403. This configuration allows the axial dimension of the shaft 1 of the magnetic torque angle sensor to be reduced.

[0042] In addition, in the shaft 1 of the magnetic torque angle sensor according to the first embodiment, the angle detecting rotor 4 has a cylindrical angle detecting central portion 401. The angle detecting non-magnetic portion 402 is ring-shaped and is provided on the outer circumferential surface 404 of the angle detecting central portion 401. With this configuration, the angle detecting central portion 401 is made of an alloy suited to the intended use of the shaft 1, thereby improving the strength of the angle detecting rotor 4.

[0043] Embodiment 2. Fig. 9 is a cross-sectional view showing the angle-detecting rotor 4 on the shaft 1 of a magnetic torque angle sensor according to embodiment 2. Fig. 10 is a cross-sectional view showing the torque-detecting rotor 5 on the shaft 1 of the magnetic torque angle sensor according to embodiment 2.

[0044] In the shaft 1 of the magnetic torque angle sensor according to the second embodiment, the angle detecting rotor 4 has an angle detecting non-magnetic portion 402 and an angle detecting magnetic portion 403. In the shaft 1 of the magnetic torque angle sensor according to the second embodiment, the angle detecting rotor 4 does not have an angle detecting central portion 401.

[0045] The angle detection non-magnetic material portion 402 is formed in a cylindrical shape. The angle detection magnetic material portion 403 is provided on an outer peripheral surface 405 of the angle detection non-magnetic material portion 402. Methods for providing the angle detection magnetic material portion 403 on the outer peripheral surface 405 of the angle detection non-magnetic material portion 402 include, for example, coating, thermal spraying, and press-fitting.

[0046] In the shaft 1 of the magnetic torque angle sensor according to the second embodiment, the torque detecting rotor 5 has a torque detecting non-magnetic portion 504 and a torque detecting magnetic portion 502. In the shaft 1 of the magnetic torque angle sensor according to the second embodiment, the torque detecting rotor 5 does not have a torque detecting central portion 501.

[0047] The torque detection non-magnetic material portion 504 is formed in a cylindrical shape. The torque detection magnetic material portion 502 is provided on an outer peripheral surface 505 of the torque detection non-magnetic material portion 504. Methods for providing the torque detection magnetic material portion 502 on the outer peripheral surface 505 of the torque detection non-magnetic material portion 504 include, for example, coating, thermal spraying, and press-fitting.

[0048] The first shaft member 3, the angle detection non-magnetic material portion 402, the torque detection non-magnetic material portion 504, and the second shaft member 6 are integrally formed with one another. In other words, the first shaft member 3, the angle detection non-magnetic material portion 402, the torque detection non-magnetic material portion 504, and the second shaft member 6 are made of the same material and are integrally formed as a single member that cannot be disassembled. The first shaft member 3, the angle detection non-magnetic material portion 402, the torque detection non-magnetic material portion 504, and the second shaft member 6 are made of non-magnetic material.

[0049] Other configurations of the shaft 1 of the magnetic torque angle sensor according to the second embodiment are the same as those of the shaft 1 of the magnetic torque angle sensor according to the first embodiment.

[0050] As described above, in the shaft 1 of the magnetic torque angle sensor according to embodiment 2, the angle-detecting non-magnetic material portion 402 is formed in a cylindrical shape. This configuration eliminates the need to form the angle-detecting non-magnetic material portion 402 in a ring shape and provide it on the outer circumferential surface 404 of the angle-detecting central portion 401. This makes it easier to manufacture the angle-detecting non-magnetic material portion 402.

[0051] In the shaft 1 of the magnetic torque angle sensor according to the second embodiment, the torque detecting rotor 5 has a torque detecting non-magnetic part 504 made of a non-magnetic material and having a cylindrical outer circumferential surface 505. The torque detecting magnetic part 502 is provided on the outer circumferential surface 505 of the torque detecting non-magnetic part 504. This configuration allows the magnetic torque angle sensor to efficiently detect changes in magnetic resistance of the torque detecting magnetic part 502. This improves the torque detection accuracy of the magnetic torque angle sensor.

[0052] In addition, in the shaft 1 of the magnetic torque angle sensor according to the second embodiment, the torque detection non-magnetic material portion 504 is formed in a cylindrical shape. This configuration makes it easy to manufacture the torque detection non-magnetic material portion 504.

[0053] In the shaft 1 of the magnetic torque angle sensor according to the second embodiment, the first shaft member 3 and the second shaft member 6 are each configured from a non-magnetic material. However, this is not limiting. At least one of the first shaft member 3 and the second shaft member 6 may be configured from a magnetic material, for example. When the first shaft member 3 is configured from a magnetic material, the angle detection non-magnetic portion 402 can be connected to the first shaft member 3 by, for example, friction welding. When the second shaft member 6 is configured from a magnetic material, the torque detection central portion 501 can be connected to the second shaft member 6 by, for example, friction welding.

[0054] 11 is a cross-sectional view showing a torque-detecting rotor on a shaft of a magnetic torque angle sensor according to embodiment 3. In the shaft 1 of the magnetic torque angle sensor according to embodiment 3, the torque-detecting rotor 5 has a torque-detecting central portion 501, a torque-detecting non-magnetic portion 504, and a torque-detecting magnetic portion 502.

[0055] The torque detection non-magnetic portion 504 is formed in a ring shape and is provided on the outer peripheral surface 503 of the torque detection central portion 501. Methods for providing the torque detection non-magnetic portion 504 on the outer peripheral surface 503 of the torque detection central portion 501 include coating, thermal spraying, and press fitting, for example.

[0056] The torque detection non-magnetic material portion 504 has a cylindrical outer peripheral surface 505. The torque detection magnetic material portion 502 is provided on the outer peripheral surface 505 of the torque detection non-magnetic material portion 504. Methods for providing the torque detection magnetic material portion 502 on the outer peripheral surface 505 of the torque detection non-magnetic material portion 504 include, for example, coating, thermal spraying, and press fitting.

[0057] Other configurations of the shaft 1 of the magnetic torque angle sensor according to embodiment 3 are the same as those of the shaft 1 of the magnetic torque angle sensor according to embodiment 1. Note that, like the shaft 1 of the magnetic torque angle sensor according to embodiment 2, the angle-detecting non-magnetic material portion 402 may be formed in a cylindrical shape.

[0058] As described above, in the shaft 1 of the magnetic torque angle sensor according to the third embodiment, the torque detecting rotor 5 has a cylindrical torque detecting central portion 501. The torque detecting non-magnetic portion 504 is formed in a ring shape and is provided on the outer circumferential surface 503 of the torque detecting central portion 501. With this configuration, the torque detecting central portion 501 is made of an alloy suited to the intended use of the shaft 1, thereby improving the strength of the torque detecting rotor 5.

[0059] In the magnetic torque angle sensor shaft 1 according to each embodiment, the axial size of the angle-detecting magnetic material portion 403 is described as varying periodically in a sinusoidal manner in response to changes in circumferential position. However, this is not limiting. The axial size of the angle-detecting magnetic material portion 403 may also vary periodically in a triangular, rectangular, or multi-step wave manner in response to changes in circumferential position.

[0060] Although the shaft 1 of the magnetic torque angle sensor according to each preferred embodiment has been described above, the present invention is not limited to the shaft 1 of the magnetic torque angle sensor according to each of the above-described embodiments. Various modifications and alterations can be made to the shaft 1 of the magnetic torque angle sensor according to each of the above-described embodiments without departing from the scope of the claims.

[0061] REFERENCE SIGNS LIST 1 shaft, 2 magnetic pole portion, 3 first shaft member, 4 angle detection rotor, 5 torque detection rotor, 6 second shaft member, 7 angle detection stator, 8 torque detection stator, 401 angle detection center portion, 402 angle detection non-magnetic portion, 403 angle detection magnetic portion, 404 outer peripheral surface, 405 outer peripheral surface, 501 torque detection center portion, 502 torque detection magnetic portion, 503 outer peripheral surface, 504 torque detection non-magnetic portion, 505 outer peripheral surface, 701 angle detection stator core, 702 angle detection coil, 703 yoke portion, 704 teeth portion, 801 torque detection stator core, 802 torque detection coil, 803 yoke portion, 804 teeth portion.

Claims

1. A shaft of a magnetic torque angle sensor comprising: an angle detection rotor (4); and a torque detection rotor (5) arranged adjacent to the angle detection rotor (4) in the axial direction, wherein the angle detection rotor (4) has an angle detection non-magnetic material portion (402) formed with a cylindrical outer circumferential surface (405) and made of a non-magnetic material, and an angle detection magnetic material portion (403) arranged on the outer circumferential surface (405) of the angle detection non-magnetic material portion (402) and made of a magnetic material, wherein the torque detection rotor (5) has a torque detection magnetic material portion (502) made of a magnetic material and formed integrally with the angle detection magnetic material portion (403), and wherein the axial size of the angle detection magnetic material portion (403) changes periodically in accordance with a change in circumferential position.

2. The shaft of the magnetic torque angle sensor according to claim 1, wherein the angle detection rotor (4) has an angle detection center portion (401) formed in a cylindrical shape, and the angle detection non-magnetic portion (402) is formed in a ring shape and is provided on the outer circumferential surface (404) of the angle detection center portion (401).

3. A shaft of a magnetic torque angle sensor according to claim 1, wherein the angle detection non-magnetic portion (402) is formed in a cylindrical shape.

4. A shaft of a magnetic torque angle sensor as described in any one of claims 1 to 3, wherein the torque detection rotor (5) has a torque detection non-magnetic part (504) made of a non-magnetic material and having a cylindrical outer circumferential surface (505), and the torque detection magnetic part (502) is provided on the outer circumferential surface (505) of the torque detection non-magnetic part (504).

5. A shaft of a magnetic torque angle sensor according to claim 4, wherein the torque detecting non-magnetic portion (504) is formed in a cylindrical shape.

6. A shaft of a magnetic torque angle sensor as described in claim 4, wherein the torque detection rotor (5) has a torque detection center portion (501) formed in a cylindrical shape, and the torque detection non-magnetic portion (504) is formed in a ring shape and is provided on the outer circumferential surface (503) of the torque detection center portion (501).

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