JP4523147B2 - Rotation angle detector - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a rotation angle detector that detects a rotation angle of a rotor that rotates relative to a stator.
[0002]
[Prior art]
[Conventional example 1]
Conventionally, as a rotation angle detector, there is a potentiometer using an annular resistor and a rotating contact. FIG. 18 is a view showing the main part of the potentiometer, 101 is an annular resistor, and 102 is a contact. The contact 102 rotates with its tip in contact with the annular resistor 101. In this potentiometer, the rotation angle of the contact 102 can be detected by measuring the resistance value between the terminals P1 and P2.
[0003]
[Conventional example 2]
FIG. 19 is a perspective view showing a main part of the rotation angle detector disclosed in Japanese Patent Application Laid-Open No. 8-327311 (Document 1). The rotation angle detector includes a solenoid coil (outer coil) 104 fixed to the base 103 and a solenoid coil (inner coil) 105 disposed inside the outer coil 104. A rotation shaft 106 extends from the base 103 and penetrates the hollow portion 104 a of the outer coil 104 in the vertical direction (a direction orthogonal to the axial direction of the coil 104), and the tip thereof is the upper surface 104 b of the outer coil 104. Stick out more. The inner coil 105 is fixed to a rotating shaft 106 that passes through the hollow portion 105a in the vertical direction (a direction orthogonal to the axial direction of the coil 105).
[0004]
In the rotation angle detector shown in this document 1, the outer coil 104 is AC-excited via a conducting wire 107 to generate an AC magnetic field. This AC magnetic field generates an induced electromotive force in the inner coil 105. The induced electromotive force generated in the inner coil 105 is proportional to the magnetic flux traversing the hollow portion 105a. This magnetic flux changes due to the angle difference between the direction of the magnetic field and the central axis of the inner coil 105, and the induced electromotive force also changes due to this angle difference. Therefore, by measuring the induced electromotive force induced in the inner coil 105, the rotation angle of the inner coil 105 relative to the outer coil 104, that is, the rotation angle of the rotation shaft 106 can be detected.
[0005]
[Problems to be solved by the invention]
In the conventional example 1 described above, since the tip of the contact 102 is rotated in contact with the annular resistor 101, there is a problem that the annular resistor 101 and the contact 102 are worn.
On the other hand, the conventional example 2 is an electromagnetic induction type (non-contact type), has no mechanical sliding portion, and does not have a problem of wear. However, in addition to the outer coil (primary coil) 104 and the rotating inner coil (secondary coil) 105, there is a flexible conductive wire 108 for taking out an output signal, and there is a problem that the configuration becomes complicated. Further, in order to generate an induced electromotive force in the inner coil 105, there is a problem that corresponding power is required and power consumption is large.
[0006]
The present invention has been made to solve such a problem, and an object of the present invention is to provide a rotation angle detector that is contactless, has a simple configuration, and has low power consumption and excellent durability. is there.
[0007]
[Means for Solving the Problems]
  In order to achieve such an object, the present invention provides a stator made of a ferromagnetic material having first to Nth (N ≧ 2) salient poles, an outer shape asymmetric with respect to the center of rotation, A rotor made of a ferromagnetic material that is positioned at a portion and rotates relatively with its outer peripheral surface facing the first to Nth salient poles of the stator, and the first to Nth salient poles of the statorEach ofAre connected to both ends of a series connection circuit of the first to Nth coils, and all the coils in the series connection circuit are AC-excited. Excitation means is provided, and the rotation angle of the rotor is detected based on the inductances of the first to Nth coils that change depending on the relative positions of the first to Nth salient poles of the stator and the rotor. .
  According to the present invention, when the rotor rotates relative to the stator, the rotor has an asymmetric outer shape with respect to the rotation center, so that the first to Nth salient poles of the stator and the rotor The reluctance of the magnetic path changes according to the rotation angle of the rotor, and the first to Nth salient poles according to the change of the reluctanceEach ofThe inductance of the first to Nth coils wound around the coil changes, and the rotation angle of the rotor can be detected without contact from the change in the inductance of the first to Nth coils. Note that the change in inductance of the first to Nth coils can be detected from the voltage across the coils..
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail based on embodiments.
[Embodiment 1]
FIG. 1 is a plan view showing a main part of a rotation angle detector showing an embodiment of the present invention. In the figure, 1 is a stator made of a ferromagnetic material, and 2 is a rotor made of a ferromagnetic material. The rotor 2 is disposed at the center of the stator 1.
[0009]
A plan view of the stator 1 is shown in FIG. 2A, and a cross-sectional view taken along line II-II in FIG. 2A is shown in FIG. The stator 1 is a ring-shaped flat plate having a thickness t1, and salient poles 1-1, 1-2, 1-3 are formed on the inner peripheral surface thereof at 120 ° intervals toward the center O1. The salient poles 1-1, 1-2 and 1-3 have the same shape, and their tips are curved surfaces having a radius R0.
[0010]
A plan view of the rotor 2 is shown in FIG. 3B is a view of FIG. 3A viewed from the A direction, and FIG. 3C is a view of FIG. 3A viewed from the B direction. The rotor 2 is a disk having a thickness t2 and a radius R1, and the left half of FIG. 3A has a radius R2 (R2 <R2 <R2) in which the central portion of the thickness t2 is formed by a width d3 and a depth d1. The outer peripheral surface of R1) is formed. In FIG. 3A, the outer peripheral surface 2-1 with the right half radius R1 is defined as the first outer peripheral surface, and the outer peripheral surface 2-2 with the left half radius R2 is defined as the second outer peripheral surface. A through hole 2-3 is formed at the center of the rotor 2.
[0011]
In the plan view shown in FIG. 1, the rotor 2 shows only the outer shape of the section taken along the line III-III in FIG. 3B in order to make the explanation of the rotation angle detection operation described later easier to understand. Although not shown in FIG. 1, yokes 4 and 4 are provided above and below the stator 1, as shown in FIG. The rotor 2 has a rotating shaft 3 inserted and fixed in the through hole 2-3. The center O1 of the stator 1 coincides with the center O2 of the rotor 2 (O = O1 = O2), and the radius R0 of the curved surface at the tip of the salient poles 1-1, 1-2, 1-3 of the stator 1 is the rotor. 2 is slightly larger than the radius R1 of the first outer peripheral surface 2-1. FIG. 4 shows a C-O-D cross section in FIG. FIG. 5A shows a plan view of the yoke 4, and FIG. 5B shows a cross-sectional view taken along line VV in FIG. 5A.
[0012]
The yoke 4 has the same planar shape as that of the stator 1. That is, projections 4-1, 4-2, 4-3 corresponding to the salient poles 1-1, 1-2, 1-3 of the stator 1 are formed on the yoke 4, and this projection 4-1. , 4-2, 4-3 are fixed to the upper and lower surfaces of the stator 1 with the yokes 4, 4 so that the salient poles 1-1, 1-2, 1-3 of the stator 1 overlap with the gap h1. Yes.
[0013]
Coils 5-1, 5-2 and 5-3 are wound around the salient poles 1-1, 1-2 and 1-3 of the stator 1. The coils 5-1, 5-2, and 5-3 are formed by sequentially winding one conductive wire around the salient poles 1-1, 1-2, and 1-3. That is, the coils 5-1, 5-2, and 5-3 are connected in series, and a fixed frequency constant voltage AC power supply 13 is connected to both ends of the series connection circuit as shown in FIG. 6. Further, the voltage V1 at both ends of the coil 5-1 is detected by the detector 6-1, the voltage V2 at both ends of the coil 5-2 is detected by the detector 6-2, and the voltage V3 at both ends of the coil 5-3 is detected. It is detected by the detector 6-3 and given to the data processing unit 7.
[0014]
In this rotation angle detector, since the rotor 2 has an asymmetric outer shape with respect to the rotation center O, when the rotor 2 rotates, the salient poles 1-1, 1-2, 1-3 of the stator 1 and the rotor 2 , Ie, the salient poles 1-1, 1-2, 1-3 of the stator 1 and the projecting parts 4-1, 4-2, 4-3 of the rotor 2 and the yokes 4, 4. The reluctance of the magnetic path changes according to the rotation angle of the rotor 2, and the coils 5-1, 5-2, 5 wound around the salient poles 1-1, 1-2, 1-3 according to the change of the reluctance. −3 changes, and the voltages V1, V2, and V3 at both ends of the coils 5-1, 5-2, and 5-3 have a constant total value, but each value changes relatively.
[0015]
FIGS. 7A to 7F show the state of rotation of the rotor 2 in the counterclockwise direction. In FIG. 7A, the first outer peripheral surface 2-1 of the rotor 2 faces the salient poles 1-1 and 1-2 of the stator 1, and the second outer peripheral surface 2-2 of the rotor 2 is the stator 1. It faces the salient pole 1-3. In this state, the voltages V1 and V2 across the coils 5-1 and 5-2 are high and the voltage V3 across the coil 5-3 is low. At this time, the rotation angle of the rotor 2 is set to 0 °. FIG. 8 shows the relationship between the rotation angle of the rotor 2 and the voltages V1, V2 and V3 across the coils 5-1, 5-2 and 5-3. When the rotation angle of the rotor 2 is 0 °, the voltages V1 and V2 across the coils 5-1 and 5-2 become VM, and the voltage V3 across the coil 5-3 becomes VL (VH> VL).
[0016]
When the rotor 2 rotates counterclockwise from the state of FIG. 7A, the second outer peripheral surface 2-2 of the rotor 2 starts to face the salient pole 1-2. As a result, the reluctance of the magnetic path formed by the salient pole 1-2, the rotor 2 and the protrusion 4-2 of the yokes 4 and 4 is changed, and the reluctance is wound around the salient pole 1-2 according to the change of the reluctance. The inductance of the coil 5-2 changes, and the voltage V2 across the coil 5-2 begins to decrease.
[0017]
FIG. 7B shows a state in which the rotor 2 is rotated 60 ° counterclockwise from the state of FIG. In this state, that is, at a rotation angle of 60 °, the first outer peripheral surface 2-1 of the rotor 2 faces the salient pole 1-1, and the second outer peripheral surface 2-2 of the rotor 2 is salient poles 1-2, 1. -3. Therefore, the voltage V1 across the coil 5-1 is VH, and the voltages V2 and V3 across the coils 5-2 and 5-3 are VL (point t1 shown in FIG. 8).
[0018]
When the rotor 2 rotates counterclockwise from the state of FIG. 7B, the first outer peripheral surface 2-1 of the rotor 2 starts to face the salient pole 1-3. As a result, the reluctance of the magnetic path formed by the salient poles 1-3 and the protrusions 4-3 of the rotor 2 and the yokes 4 and 4 is changed, and the reluctance is wound around the salient poles 1-3 according to the change of the reluctance. The inductance of the coil 5-3 changes, and the voltage V3 across the coil 5-3 starts to rise.
[0019]
FIG. 7C shows a state in which the rotor 2 has rotated 60 ° counterclockwise from the state of FIG. 7B. In this state, that is, at a rotation angle of 120 °, the first outer peripheral surface 2-1 of the rotor 2 faces the salient poles 1-1 and 1-3, and the second outer peripheral surface 2-2 of the rotor 2 is the salient pole 1. -2. Therefore, the voltages V1 and V3 at both ends of the coils 5-1 and 5-3 are VM, and the voltage V2 at both ends of the coil 5-2 is VL (point t2 shown in FIG. 8).
[0020]
When the rotor 2 rotates counterclockwise from the state of FIG. 7C, the rotor 2 starts to face the second outer peripheral surface 2-2 of the rotor 2 with respect to the salient pole 1-1. As a result, the reluctance of the magnetic path formed by the salient pole 1-1, the rotor 2 and the protrusion 4-1 of the yokes 4 and 4 is changed, and the reluctance is wound around the salient pole 1-1 according to the change of the reluctance. The inductance of the coil 5-1 changes, and the voltage V1 across the coil 5-1 begins to decrease.
[0021]
FIG. 7D shows a state in which the rotor 1 is rotated 60 ° counterclockwise from the state of FIG. In this state, that is, at a rotation angle of 180 °, the first outer peripheral surface 2-1 of the rotor 2 faces the salient pole 1-3, and the second outer peripheral surface 2-2 of the rotor 2 is salient poles 1-1, 1. -2. Therefore, the voltages V1 and V2 at both ends of the coils 5-1 and 5-2 are VL, and the voltage V3 at both ends of the coil 5-3 is VH (point t3 shown in FIG. 8).
[0022]
Similarly, at a rotation angle of 240 ° (FIG. 7E), the voltage V1 across the coil 5-1 is VL, and the voltages V2 and V3 across the coils 5-2 and 5-3 are VM ( At point t4 shown in FIG. 8), at a rotation angle of 300 ° (FIG. 7 (f)), voltages V1 and V3 at both ends of coils 5-1 and 5-3 are VL, and voltage V2 at both ends of coil 5-2 is VH. (Point t5 shown in FIG. 8), at a rotation angle of 360 ° (FIG. 7A), voltages V1 and V2 at both ends of coils 5-1 and 5-2 are VM, and voltage V3 at both ends of coil 5-3. Becomes VL (point t6 shown in FIG. 8).
[0023]
As can be seen from FIG. 8, the voltages V <b> 1, V <b> 2 and V <b> 3 generated at both ends of the coils 5-1, 5-2 and 5-3 have different combinations of values depending on the rotation angle of the rotor 2. Therefore, if the voltages V1, V2, and V3 generated at both ends of the coils 5-1, 5-2, and 5-3 are measured and processed, the rotation angle of the rotor 2 can be known.
The data processor 7 receives the voltages V1, V2 and V3 from the detectors 6-1, 6-2 and 6-3, and the rotor 2 according to the characteristics shown in FIG. 8 from the values of the voltages V1, V2 and V3. Find the rotation angle of.
[0024]
The calculation of the rotation angle in the data processing unit 7 may be performed by a hardware circuit. However, if the calculation is performed by a software operation using a microprocessor or the like, the circuit configuration is simplified. FIG. 9 shows a schematic configuration of the data processing unit 7 when a microprocessor is used. In the figure, 7-1 is a CPU, 7-2 is a ROM, 7-3 is a RAM, 7-4 and 7-5 are interfaces, and the CPU 7-1 is voltages V1, V2 and V3 via the interface 7-4. The rotation angle is calculated while accessing the RAM 7-3 according to the program stored in the ROM 7-2. In this case, the RAM 7-3 stores in advance the relationship between the voltages V1, V2, V3 and the rotation angle shown in FIG.
[0025]
In this embodiment, the yoke 4 is provided above and below the stator 1, but the yoke 4 may be provided only on the upper side or the lower side. Further, the yoke 4 does not have to be ring-shaped with the protrusions 4-1, 4-2 and 4-3, that is, 1 with respect to the salient poles 1-1, 1-2 and 1-3 of the stator 1. Two connected yokes may not be provided, and an independent yoke may be provided for each of the salient poles 1-1, 1-2, and 1-3. Further, the stator 1 and the yoke 4 may be integrated without being separated.
[0026]
Further, the outer shape of the rotor 2 does not necessarily have to be the shape shown in the drawing. That is, it is only necessary to have an asymmetric outer shape with respect to the center of rotation. For example, the outer shape of the rotor 2 may be a perfect circle, and the perfect circle may be eccentric and rotated. Further, although the rotor 2 is rotated, the stator 1 may be rotated. However, in this case, since the coils 5-1 5-2, and 5-3 need to be supplied with power via a slip ring, for example, the structure is slightly complicated.
[0027]
[Embodiment 2]
In the first embodiment, the number of salient poles is three. However, the number of salient poles may be two if the measurement target angle is 180 ° or less. FIG. 10 shows a main part of a rotation angle detector having two salient poles. In this example, salient poles 8-1 and 8-2 are formed on the inner peripheral surface of the stator 8 at intervals of 180 °. Coils 10-1 and 10-2 are wound around the salient poles 8-1 and 8-2. The rotor 9 has a small diameter of 1/4 of its outer peripheral surface. In other words, the rotor 9 has 3/4 of the outer peripheral surface as the first outer peripheral surface 9-1 having the radius R1, and the remaining 1/4 as the second outer peripheral surface 9-2 having the radius R2. In this case, the outer shape of the second outer peripheral surface 9-2 is asymmetric with respect to the rotation center O. Although not shown in the drawing, yokes having the same planar shape are provided above and below the stator 8.
[0028]
The coils 10-1 and 10-2 are connected in series, and a fixed frequency constant voltage AC power source 13 is connected to both ends of the series connection circuit as shown in FIG. Further, the voltage V1 at both ends of the coil 10-1 is detected by the detector 11-1, the voltage V2 at both ends of the coil 10-2 is detected by the detector 10-2, and is supplied to the data processing unit 12. .
[0029]
In this rotation angle detector, since the rotor 9 has an asymmetrical outer shape with respect to the rotation center O, when the rotor 9 rotates, there is a gap between the salient poles 8-1 and 8-2 of the stator 8 and the rotor 9. The reluctance of the magnetic path changes according to the rotation angle of the rotor 9, and the inductances of the coils 10-1 and 10-2 wound around the salient poles 8-1 and 8-2 change according to the change of the reluctance, The total values of the voltages V1 and V2 across the coils 10-1 and 10-2 are constant, but each value changes relatively.
[0030]
FIGS. 12A to 12D show the state of rotation of the rotor 9 in the counterclockwise direction. In FIG. 12A, the first outer peripheral surface 9-1 of the rotor 9 faces the salient pole 8-1 of the stator 8, and the second outer peripheral surface 9-2 of the rotor 9 is the salient pole 8 of the stator 8. -2. In this state, the voltage V1 across the coil 10-1 is high and the voltage V2 across the coil 10-2 is low. At this time, the rotation angle of the rotor 9 is set to 0 °. FIG. 13 shows the relationship between the rotation angle of the rotor 9 and the voltages V1 and V2 across the coils 10-1 and 10-2. The voltage V1 across the coil 10-1 at a rotation angle 0 ° of the rotor 9 is VH, and the voltage V2 across the coil 10-2 is VL (VH> VL).
[0031]
When the rotor 9 rotates counterclockwise from the state of FIG. 12A, the first outer peripheral surface 9-1 of the rotor 9 starts to face the salient pole 8-2. As a result, the reluctance of the magnetic path between the salient pole 8-2 and the rotor 9 changes, and the inductance of the coil 10-2 wound around the salient pole 8-2 changes according to the change in reluctance. The voltage V2 across 10-2 begins to rise.
[0032]
FIG. 12B shows a state in which the rotor 2 is rotated 90 ° counterclockwise from the state of FIG. In this state, that is, at a rotation angle of 90 °, the first outer peripheral surface 9-1 of the rotor 9 faces both the salient poles 8-1, 8-2. For this reason, the voltages V1 and V2 across the coils 10-1 and 10-2 are both VM (point t1 shown in FIG. 13).
[0033]
When the rotor 9 rotates counterclockwise from the state of FIG. 12B, the second outer peripheral surface 9-2 of the rotor 9 starts to face the salient pole 8-1. As a result, the reluctance of the magnetic path between the salient pole 8-1 and the rotor 9 changes, and the inductance of the coil 10-1 wound around the salient pole 8-1 changes according to the change of the reluctance. The voltage V1 across 10-1 begins to drop.
[0034]
FIG. 12C shows a state where the rotor 2 is rotated 90 ° counterclockwise from the state shown in FIG. In this state, that is, at a rotation angle of 180 °, the first outer peripheral surface 9-1 of the rotor 9 faces the salient pole 8-2, and the second outer peripheral surface 9-2 faces the salient pole 8-1.
Therefore, the voltage V1 at both ends of the coil 10-1 is VL, and the voltage V2 at both ends of the coil 10-2 is VH (point t2 shown in FIG. 13).
[0035]
Similarly, at a rotation angle of 270 ° (FIG. 12 (d)), the voltages V1 and V2 across the coils 10-1 and 10-2 are both VM (point t3 shown in FIG. 13), and the rotation angle is 360. In FIG. 12A (FIG. 12A), the voltage V1 across the coil 10-1 is VH, and the voltage V2 across the coil 10-2 is VL (point t4 shown in FIG. 13).
[0036]
As can be seen from FIG. 13, the voltages V1 and V2 generated at both ends of the coils 10-1 and 10-2 have the same combination value when exceeding 180 °. Value. Therefore, if the voltages V1 and V2 generated at both ends of the coils 5-1 and 5-2 are measured and processed, the rotation angle of the rotor 2 can be known in the range of 0 to 180 °. The data processing unit 12 receives the voltages V1 and V2 from the detectors 11-1 and 11-2, and follows the characteristics shown in FIG. 13 (characteristics in the range of 0 to 180 °) from the values of the voltages V1 and V2. The rotation angle of the rotor 9 is obtained.
[0037]
Also in the second embodiment, a yoke may be provided only on the upper side or the lower side of the stator 9. An independent yoke may be provided for each of the salient poles 9-1 and 9-2 of the stator 9. It goes without saying that the yoke may be integrated, the outer shape of the rotor 9 may be a perfect circle, the perfect circle may be eccentric and rotated, or the stator 9 side may be rotated.
[0038]
[Reference example]
  In the first embodiment, the number of salient poles is three, and in the second embodiment, the number of salient poles is two. However, the number of salient poles may be further increased.. As a reference example in FIG.The main part of the rotation detector with one salient pole is shown. In this example, one salient pole 14-1 is formed on the inner peripheral surface of the annular stator 14, and a coil 16 is wound around the salient pole 14-1.
[0039]
The radius of the outer peripheral surface of the rotor 15 is gradually increased from the P1 position counterclockwise. Thereby, the outer shape of the rotor 15 is asymmetric with respect to the rotation center O in the entire region. Although not shown in the drawing, yokes having the same planar shape are provided above and below the stator 14.
[0040]
As shown in FIG. 15, a constant voltage AC power source 13 having a fixed frequency is connected to the coil 16, and a current I <b> 1 flowing through the coil 16 is detected by a detector 20 and supplied to a data processing unit 21.
[0041]
In this rotation angle detector, since the rotor 15 has an asymmetric outer shape with respect to the rotation center O, the reluctance of the magnetic path between the salient poles 14-1 of the stator 14 and the rotor 15 when the rotor 15 rotates. Changes according to the rotation angle of the rotor 15, the inductance of the coil 16 wound around the salient pole 14-1 changes according to the change in reluctance, and the current I1 flowing through the coil 16 changes.
[0042]
In this case, the radius of the outer peripheral surface of the rotor 5 is gradually increased counterclockwise from the P1 position, so that the salient pole 14-1 and the outer peripheral surface of the rotor 15 are rotated as the rotor 15 rotates clockwise. The facing gap is narrowed, and the current I1 flowing through the coil 16 gradually increases linearly (see FIG. 16). The data processing unit 21 receives the current I1 from the detector 20, and obtains the rotation angle of the rotor 15 from the value of the current I1 according to the characteristics shown in FIG.
[0043]
  thisReference exampleHowever, the yoke may be provided only on the upper side or the lower side of the stator 14, an independent yoke is provided for the salient pole 14-1 of the stator 14, the stator 14 and the yoke are integrated, or the rotor Needless to say, the outer shape of 15 may be a perfect circle, and the perfect circle may be eccentric and rotated, or the stator 14 side may be rotated. Further, the stator 14 does not necessarily have an annular shape.
[0044]
  In addition, the above-described embodiment1, 2 and reference examplesThen, although the constant voltage alternating current power supply 13 was used as a power supply, you may make it use a constant current alternating current power supply.
  For example, as shown in FIG.Reference exampleA constant current AC power source 13 ′ having a fixed frequency may be connected to the coil 16, and the constant current i may be supplied from the constant current AC power source 13 ′ to the coil 16. In this case, since the voltage V1 across the coil 16 changes due to the change in the inductance of the coil 16, the rotation angle of the rotor 15 can be detected from the value of the voltage V1.
[0045]
As shown in FIG. 17 (b), a constant frequency constant current AC power supply 13 'is connected to the series-connected coils 5-1, 5-2 and 5-3 of the first embodiment, and this constant current is connected. A constant current i may be supplied from the AC power supply 13 'to the coils 5-1, 5-2, and 5-3. In this case, the voltages V1, V2, and V3 at both ends of the coils 5-1, 5-2, and 5-3 change due to changes in the inductance of the coils 5-1, 5-2, and 5-3. The rotation angle of the rotor 2 can be detected from the values of V2 and V3.
[0047]
  In the above description, the “constant voltage value” of the constant voltage AC power supply 13 and the “constant current value” of the constant current AC power supply 13 ′ do not necessarily have to be “a constant value”. In other words, as long as you know the value of the applied voltage or the value of the same current,Ratio of each coil voltageIt is also possible to know the rotation angle from this ratio by measuring.
[0048]
【The invention's effect】
As is apparent from the above description, according to the present invention, when the rotor rotates relative to the stator, the rotor has an asymmetric outer shape with respect to the rotation center. The reluctance of the magnetic path between them changes according to the rotation angle of the rotor, the inductance of the coil wound around the salient pole changes according to the change of the reluctance, and the rotation angle of the rotor does not contact from this change in inductance Will be detected. For this reason, the problem of friction does not occur and the durability is excellent. Further, the secondary coil as in Conventional Example 2 is not required, there is no need for a flexible conductor, and power consumption is reduced.
[Brief description of the drawings]
FIG. 1 is a plan view showing a main part of an embodiment (Embodiment 1) of a rotation angle detector according to the present invention.
FIG. 2 is a plan view and a side sectional view of a stator used in this rotation angle detector.
FIG. 3 is a plan view and a side view of a rotor used in the rotation angle detector.
FIG. 4 is a cross-sectional view (C-O-D cross-sectional view in FIG. 1) showing an assembled state of the rotation angle detector.
FIG. 5 is a plan view and a side sectional view of a yoke used in the rotation angle detector.
FIG. 6 is a diagram showing an electric circuit of the rotation angle detector.
FIG. 7 is a diagram showing a state of rotation of the rotor of the rotation angle detector in the counterclockwise direction.
FIG. 8 is a diagram showing the relationship between the rotation angle of the rotor of this rotation angle detector and the voltages V1, V2, and V3 at both ends of each coil.
FIG. 9 is a diagram showing a schematic configuration of a data processing unit when a microprocessor is used.
FIG. 10 is a plan view showing a main part of another embodiment (Embodiment 2) of the rotation angle detector according to the present invention.
FIG. 11 is a diagram showing an electric circuit of the rotation angle detector.
FIG. 12 is a diagram showing a state of rotation of the rotor of the rotation angle detector in the counterclockwise direction.
FIG. 13 is a diagram showing the relationship between the rotation angle of the rotor of this rotation angle detector and the voltages V1 and V2 at both ends of each coil.
FIG. 14 is a plan view showing a main part of another embodiment (Embodiment 3) of a rotation angle detector according to the present invention.
FIG. 15 is a diagram showing an electric circuit when a rotation angle is detected from a current flowing through a coil in the third embodiment.
FIG. 16 is a diagram showing the relationship between the rotation angle of the rotor of this rotation angle detector and the current I1 flowing through the coil.
17 is a diagram showing a main part of an electric circuit when a constant current AC power supply is used in the third embodiment or the first embodiment. FIG.
FIG. 18 is a view showing a main part of a conventional rotation angle detector (potentiometer).
FIG. 19 is a perspective view showing a main part of a rotation angle detector disclosed in Japanese Patent Application Laid-Open No. 8-327311 (Document 1).
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Stator, 1-1, 1-2, 1-3 ... Salient pole, 2 ... Rotor, 2-1 ... 1st outer peripheral surface, 2-2 ... 2nd outer peripheral surface, 3 ... Rotating shaft, 4 ... Yoke, 5-1, 5-2, 5-3 ... Coil, 6-1, 6-2, 6-3 ... Detector, 7 ... Data processing unit, 8 ... Stator, 8-1, 8-2 ... Projection Pole, 9 ... Rotor, 9-1 ... First outer peripheral surface, 9-2 ... Second outer peripheral surface, 10-1, 10-2 ... Coil, 11-1, 11-2 ... Detector, 12 ... Data Processing part, 13 ... Constant voltage AC power supply, 13 '... Constant current AC power supply, 14 ... Stator, 14-1 ... Salient pole, 15 ... Rotor, 16 ... Coil, 17 ... Series resistance, 18 ... Detector, 19 ... Data Processing unit, 20 ... detector, 21 ... data processing unit.

Claims (1)

A stator made of a ferromagnetic material having first to Nth (N ≧ 2) salient poles;
A rotor having a non-symmetrical outer shape with respect to the center of rotation, which is located at the center portion of the stator and which rotates relatively with its outer peripheral surface facing the first to Nth salient poles of the stator. When,
First to Nth coils wound around each of the first to Nth salient poles of the stator and all connected in series;
Excitation means connected to both ends of the series connection circuit of the first to Nth coils, and AC exciting the coil in the series connection circuit;
And means for detecting a rotation angle of the rotor based on inductances of the first to Nth coils, which vary depending on a relative position between the first to Nth salient poles of the stator and the rotor. Rotation angle detector.

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