JP5620728B2 - Rotation angle detector - Google Patents

Description

  The present invention relates to a rotation angle detection device that detects a rotation angle of a rotating body.

  In recent years, for example, in a power steering device or an air conditioner mounted on an automobile, a so-called brushless motor is often used as a motor serving as a driving source. This brushless motor generally has a rotor formed of permanent magnets and a stator made of a coil that can be energized, and an electromagnetic force corresponding to the electric power supplied to the stator is applied to the rotor to cause the motor to move. The rotating shaft is rotated. The brushless motor is usually provided with a rotation angle detection device that detects the rotation angle of the rotor, and controls power feeding to the stator based on the rotation angle of the rotor detected through the rotation angle detection device. Thus, the rotation mode of the rotation shaft of the motor is controlled.

  As such a rotation angle detection device for detecting the rotation angle of a rotor or a rotation body such as a rotation shaft, for example, the one described in Patent Document 1 is known. This rotation angle detection device has a pulse ring that rotates integrally with a rotating body, an excitation coil that is disposed to face the outer peripheral surface of the pulse ring, and a detection coil that is disposed inside the excitation coil. doing. Here, the pulse ring is a member made of a magnetic material, and grooves are formed at predetermined intervals in the rotation direction. In the rotation angle detection device configured as described above, an eddy current is generated in the pulse ring by the excitation coil, and the magnetic flux generated by the eddy current is detected by the detection coil. Since the pulse ring is formed with grooves at predetermined intervals, when the pulse ring rotates, the eddy current changes depending on the presence or absence of the groove. As the eddy current changes, the magnetic flux detected by the detection coil also changes. In this rotation angle detection device, the rotation angle of the rotating body is calculated based on the voltage induced in the detection coil that changes in accordance with the change in magnetic flux.

JP 2006-10366 A

  In the rotation angle detection device of Patent Document 1, when the pulse ring rotates, the rotation angle is detected by detecting a magnetic field that changes depending on the presence or absence of a groove formed in the pulse ring. In patent document 1, since this rotation angle detection apparatus is utilized for a bearing, the axis deviation of a rotary body is not assumed. However, when the rotational angle detection device of this configuration is applied to a device that may cause an axis deviation, for example, a motor, the distance between the excitation coil and the pulse ring or the distance between the detection coil and the pulse ring is assumed to change. Is done. The voltage induced in the detection coil also changes when the distance between the excitation coil and the pulse ring or the distance between the detection coil and the pulse ring changes. In such a situation, it may be unclear whether the change in the voltage induced in the detection coil is due to axial misalignment or due to detection of the presence or absence of a groove accompanying the rotation of the pulse ring. Therefore, in order to solve this, it is necessary to provide another sensor for detecting the axis deviation of the rotating body. However, providing other sensors leads to an increase in the number of parts. Therefore, it has been desired to develop a rotation angle detection device that can detect the axial deviation of the rotating body.

  The present invention has been made in view of such a situation, and an object of the present invention is to provide a rotation angle detection device capable of detecting an axial deviation of a rotating body using a configuration used for detection of the rotation angle. is there.

In order to solve the above-mentioned problem, the invention of claim 1 is a rotation angle detection device that detects a rotation angle of a disk-like rotating body that rotates integrally with a detection object as a rotation angle of the detection object. Is provided with a plurality of grooves extending in the radial direction of the disk surface at an angular interval in the rotation direction, and according to the magnetic field generated from the rotating body that changes depending on the presence or absence of the grooves when the rotating body rotates. A plurality of sensors for generating a signal that is opposed to the disk surface, obtaining a rotation angle of the rotating body based on a signal generated by the sensor, and detecting the presence or absence of an axis deviation of the rotating body. The gist.

According to this configuration, by providing a plurality of sensors facing the disk surface, the sensors can detect the axial deviation of the rotating body. Further, a groove extending in the radial direction is formed on the disk surface. The sensor detects the rotation angle of the rotating body by detecting the presence or absence of the groove . Further, the sensor can detect the axial deviation by changing the positional relationship between the sensor and the groove when the rotating body is misaligned. That is, according to this configuration, it is possible to detect the axial deviation of the rotating body with the configuration necessary for detecting the rotation angle of the rotating body.

According to a second aspect of the present invention, in the rotational angle detection device according to the first aspect, a plurality of grooves are provided at first angular intervals on the first disk surface of the rotating body, and the first circular surface is provided. The second disk surface opposite to the disk surface is provided with a plurality of grooves at a second angle interval different from the first angle interval, and a plurality of sensors are provided on each of the first and second disk surfaces. The gist is that they are provided opposite to each other.

According to this configuration, the rotation angle detection device can detect the rotation angle from both sides because the angular intervals of the plurality of grooves provided on the first and second disk surfaces of the rotating body are different. For this reason, in this rotation angle detection device, it is possible to calculate an absolute angle in one rotation (360 °) of the rotating body.

  According to a third aspect of the present invention, in the rotation angle detecting device according to the second aspect, the sensors facing the first and second disk surfaces are opposite to each other across the rotation axis of the rotating body. The gist is that two are provided.

  According to the same configuration, when the rotational axis of the rotating body is tilted, when the one sensor and the rotating body are close to each other, the other sensor and the rotating body are separated from each other. Therefore, a strong magnetic field is applied to one sensor, and a weak magnetic field is applied to the other sensor. That is, the strengths of the magnetic fields applied to the two sensors facing the same disk surface are different. As described above, the two sensors facing the same disk surface are provided on the opposite sides of the rotating shaft of the rotating body, so that an axial deviation when the rotating shaft of the rotating body is tilted can be easily detected. .

The invention according to claim 4 is the rotational angle detection device according to claim 3, wherein the angular interval between the two sensors provided across the rotational axis of the rotating body is different from the angular interval of the groove. And

  When the signals output from the two sensors coincide with each other, one of the sensors is a sensor that detects only the axis deviation of the rotating body. According to the configuration, the signals output from the two sensors are displaced. In other words, the rotation angle of the rotating body can be detected from the grooves formed on the same surface by two methods, and therefore the angle of the rotating body can be detected with high accuracy.

The invention described in claim 5, in the rotation angle detection apparatus according to claim 1, wherein the rotary member is electrically conductive materials or Rannahli, the sensor disc face of the rotating body An excitation coil that generates an eddy current on the disk surface by applying an alternating magnetic field to the disk, and a detection coil that detects a change in the magnetic field caused by the eddy current generated on the disk surface of the rotating body, The gist of the present invention is an eddy current flaw detection sensor that detects the proximity of the groove based on a change in magnetic field detected through a detection coil.

  According to this configuration, it is possible to easily configure a rotating body suitable for detection of a rotation angle only by forming a groove in a cylindrical conductive material.

  In the present invention, it is possible to provide a rotation angle detection device that can detect the axial deviation of the rotating body by using the configuration used for detecting the rotation angle.

The schematic diagram showing one embodiment of the rotation angle detection device in the present invention. (A) is a top view which shows the mounting position of the eddy current flaw detection sensor with respect to the disk surface of the left side of the rotary body in the embodiment, (b) is an eddy current flaw detection sensor with respect to the disk surface of the right side of the rotator in the same embodiment. The top view which shows the mounting position. (A) is a perspective view schematically showing the structure of the eddy current flaw detection sensor and the flow mode of the eddy current, and (b) schematically shows the flow mode of the eddy current when there is a groove in the vicinity of the eddy current flaw detection sensor. FIG. (A) is a perspective view showing a state in which the rotating body is off-axis and the distance between the rotating body and the eddy current flaw detection sensor is larger than the reference distance, and (b) is the same rotation with the rotating body off-axis. The perspective view which shows the state where the distance of a body and an eddy current flaw detection sensor is nearer than a reference distance. (A) shows a case where the distance between the eddy current flaw detection sensor and the rotating body is standard, and (b) shows a case where the distance between the eddy current flaw detection sensor and the rotation body is long, or a groove in the vicinity of the eddy current flaw detection sensor. (C) is a figure which shows the waveform of the alternating voltage induced by the detection coil when the distance of an eddy current flaw detection sensor and a rotary body approaches. (A) is a figure which shows the waveform of the alternating voltage output to an exciting coil, (b)-(e) is a figure which shows the waveform of the alternating voltage induced by a detection coil. The figure which shows the angle response | compatibility used for calculation of the absolute angle of a rotary body stored in a control apparatus. The perspective view which shows the axial deviation aspect of the rotary body in the embodiment. (A)-(f) is a figure which shows the waveform of the alternating voltage induced by each detection coil when a rotary body carries out an axial shift in each direction of AF in FIG. (A) is a plan view of the right disk surface of the rotating body when the rotating body is off-axis in the E direction in FIG. 8, and (b) is the same view when the rotating body is off-axis in the F direction in FIG. The top view of the right disk surface of a rotary body.

Hereinafter, an embodiment of a rotation angle detection device according to the present invention will be described with reference to the drawings.
As shown in FIG. 1, the motor shaft 11 of the brushless motor 10 is provided with a rotating body 20 that rotates integrally with the motor shaft 11. The rotating body 20 is made of a conductive material and has a disk shape. As shown in FIG. 2A and FIG. 2B, the left surface (first disk surface) of the rotating body 20 has five grooves D (one for every 72 °) extending in the radial direction. Similarly, six grooves D (one for every 60 °) extending in the radial direction are formed on the right surface (second disk surface), respectively. The grooves D are provided on the left surface and the right surface of the rotating body 20 at regular intervals in the rotation direction.

  As shown in FIG. 1, a total of four eddy current flaw detection sensors 30 (30A, 30B, 30C, 30D) are provided on the left and right sides of the rotating body 20. The eddy current flaw detection sensors 30A and 30B are opposed to the left surface of the rotator 20, and the eddy current flaw sensors 30C and 30D are opposed to the right surface of the rotator 20, respectively. The eddy current flaw detection sensors 30 </ b> A and 30 </ b> B and the eddy current flaw detection sensors 30 </ b> C and 30 </ b> D are provided on opposite sides of the motor shaft 11.

  The eddy current flaw detection sensor 30 includes an excitation coil 31 and a detection coil 32 provided inside thereof, and the axial direction thereof is perpendicular to the disk surface (left surface and right surface) of the rotating body 20 (motor shaft). 11 in the same axial direction). The exciting coil 31 (31A, 31B, 31C, 31D) applies an alternating magnetic field to the disk surface of the rotating body 20 based on the supply of the AC voltage, and applies to the surface of the rotating body 20 (here, the disk surface). Generate eddy currents. On the other hand, the detection coil 32 (32A, 32B, 32C, 32D) is induced by a magnetic field (alternating magnetic field) generated by an eddy current and outputs an alternating voltage. The alternating voltage that induces the detection coil 32 varies depending on the presence or absence of the groove D accompanying the rotation of the rotating body 20.

  Each eddy current flaw detection sensor 30 is electrically connected to the control device 12. The control device 12 detects the rotation angle of the rotating body 20, that is, the motor shaft 11 based on the supply control of the AC voltage to each excitation coil 31 and the AC voltage induced in each detection coil 32. Further, the control device 12 also detects the axial deviation of the rotating body 20 based on the detection result of each detection coil 32.

  As shown in FIG. 2A, the excitation coil 31 and the detection coil 32 are provided concentrically. Now, if the position of the eddy current flaw detection sensor 30A provided on the upper side of the motor shaft 11 is 0 ° with respect to the shaft center (motor shaft 11) of the rotating body 20, the eddy current flaw detection sensor 30B on the lower side of the motor shaft 11 is , 162 ° (72 ° + 72 ° + 18 ° (= 72 ° / 4)). In other words, the eddy current flaw detection sensor 30B is arranged at a position (18 °) shifted in the clockwise direction by a quarter period from the groove interval (72 ° here) with respect to the eddy current flaw detection sensor 30A.

  On the other hand, as shown in FIG. 2B, when the position of the eddy current flaw detection sensor 30C provided on the upper side of the motor shaft 11 is set to 0 ° with respect to the axis of the rotating body 20, the vortex on the lower side of the motor shaft 11 is obtained. The current flaw detection sensor 30D is provided at a position of 195 ° (60 ° + 60 ° + 60 ° + 15 ° (= 60 ° / 4)). That is, the eddy current flaw detection sensor 30D is arranged at a position (15 °) shifted clockwise by a quarter period from the groove interval (60 ° here) with respect to the eddy current flaw detection sensor 30C.

In the following, the eddy current sensor 30A, 30B, 30C, the detection principle of the distance 30D and the rotary member 20, and the detection principle of a groove D which is provided on the rotating body 20 will be described. Here, the eddy current flaw detection sensor 30A will be described representatively.

  As shown in FIG. 3A, in this eddy current flaw detection sensor 30A, the excitation coil 31A applies an alternating magnetic field to the detection object (here, the rotating body 20) through the supply of an AC voltage having a constant frequency. As a result, an eddy current Iw is generated on the outer peripheral surface of the rotating body 20. In the detection coil 32A, an alternating voltage is induced by a combined magnetic field of an alternating magnetic field induced by the eddy current Iw and an alternating magnetic field induced by the alternating voltage supplied to the exciting coil 31A.

  As shown in FIG. 3A, when the groove D does not exist immediately below or in the vicinity of the eddy current flaw detection sensor 30A, even if the rotator 20 rotates, the eddy current flaw detection sensor 30A and the rotator The distance from the outer peripheral surface 20 is constant (reference distance). When an AC voltage is applied to the exciting coil 31A, an eddy current Iw is generated on the surface of the rotating body 20. At this time, an AC voltage shown in FIG. 5A is induced in the detection coil 32A by the eddy current Iw. That is, the AC voltage (amplitude) induced in the detection coil 32A is kept at a constant value according to the distance between the eddy current flaw detection sensor 30A and the disk surface of the rotating body 20.

  As shown in FIG. 4A, when the rotating body 20 is misaligned and the distance between the outer peripheral surface of the rotating body 20 and the eddy current flaw detection sensor 30A becomes larger than the reference distance, FIG. ), The AC voltage (amplitude) induced in the detection coil 32A becomes small. On the other hand, as shown in FIG. 4B, when the distance between the outer peripheral surface of the rotating body 20 and the eddy current flaw detection sensor 30A is smaller than the reference distance, the detection is performed as shown in FIG. The AC voltage (amplitude) induced in the coil 32A increases.

  The control device 12 can detect the axial deviation of the rotating body 20 by detecting the distance between the outer peripheral surface of the rotating body 20 and the detecting coil 32A based on the magnitude of the AC voltage induced by the detecting coil 32A.

  Further, the magnitude of the AC voltage induced in the detection coil 32A also changes depending on the presence or absence of the groove D. As shown in FIG. 4B, when the rotating body 20 rotates in the direction of the arrow and there is a groove D or the like directly below or in the vicinity of the eddy current flaw detection sensor 30A, the flow of the eddy current Iw. Changes. For example, as compared with the state shown in FIG. 3A, a part of the eddy current Iw is blocked by the groove D in the state shown in FIG. That is, the area where the eddy current Iw flows favorably decreases. The strength of the magnetic field generated by the eddy current Iw is proportional to the size of the area through which the eddy current Iw flows. Therefore, in the situation shown in FIG. 3B, the AC voltage (amplitude) induced in the detection coil 32A becomes small as shown in FIG.

  Thus, in the eddy current flaw detection sensor 30A, the presence or absence of the groove D can be detected by a change in the alternating voltage induced in the detection coil 32A. In addition, the detection of the axial deviation of the rotating body 20 and the presence or absence of the groove D can be performed in any of the eddy current flaw detection sensors 30A, 30B, 30C, and 30D.

Next, a detection mode of the rotation angle when the rotating body 20 rotates on the premise that the rotating body 20 is not misaligned will be described.
Each excitation coil 31A, 31B, 31C, 31D to which the alternating voltage having the waveform shown in FIG. 6A is applied from the control device 12 generates eddy currents on the surface (disk surface) of the rotating body 20 that faces each other. generate. In this case, the waveform of the alternating voltage induced in the detection coils 32A, 32B, 32C, and 32D is shown in FIGS. 6B, 6C, 6D, and 6E, respectively. .

  Since the groove D is formed on the left surface of the rotating body 20 every 72 °, the waveform of the AC voltage induced in the detection coils 32A and 32B is as shown in FIGS. 6 (b) and 6 (c). In addition, the amplitude is remarkably reduced every 72 °. In addition, since the detection coil 32B is shifted from the detection coil 32A by a quarter of the interval of the groove D, the waveform of the AC voltage induced in the detection coil 32B is induced in the detection coil 32A. The phase is shifted by a quarter period (18 °) with respect to the waveform of the alternating voltage.

  Since the groove D is formed on the right surface of the rotating body 20 every 60 °, the waveform of the AC voltage induced in the detection coils 32C and 32D is as shown in FIGS. 6 (d) and 6 (e). In addition, the amplitude is remarkably reduced every 60 °. Further, since the detection coil 32D is arranged with a shift of one-quarter of the interval of the groove D with respect to the detection coil 32C, the waveform of the AC voltage induced in the detection coil 32D is induced in the detection coil 32C. The phase is shifted by a quarter period (15 °) with respect to the waveform of the alternating voltage.

  The control device 12 calculates the rotation angle of the rotating body 20 based on the waveform of the alternating voltage induced in the detection coils 32A and 32B and the detection coils 32C and 32D. The control device 12 first calculates the rotation angles θ1 and θ2 of the rotating body 20 in the angle range (72 °, 60 °) between the two adjacent grooves D on the left and right surfaces of the rotating body 20.

  In this example, the detection coils 32A and 32B output an alternating voltage (sine wave, cosine wave) shifted by a quarter cycle. The control device 12 applies the voltage value V obtained from these to the equation (1), thereby setting the rotation angle θ1 of the rotating body 20 in the angle range (72 °) between the two grooves D adjacent in the rotation direction. Identify.

θ = arctanV (1)
Since the waveform of the voltage induced in the detection coils 32A and 32B is shifted by a quarter period, the angle θ1 can be accurately specified from the shift of the period. Similarly, from the voltages induced in the detection coils 32C and 32D, the rotation angle θ2 of the rotating body 20 in the angle range (60 °) of two adjacent grooves D on the right surface of the rotating body 20 is obtained.

  The storage device of the control device 12 stores an angle correspondence table as shown in FIG. The controller 12 determines the rotation angles θ1 and θ2 on the left and right surfaces of the rotating body 20 specified from the waveform of the alternating voltage induced in the detection coils 32A, 32B, 32C, and 32D, and the angle correspondence table shown in FIG. The rotation angle θ during one rotation (360 °) of the rotating body 20, that is, the motor shaft 11, is detected as an absolute value. For example, when the rotation angle θ1 on the left surface of the rotating body 20 is 24 ° and the rotation angle θ2 on the right surface of the rotating body 20 is 36 °, the rotation angle of the motor shaft 11 is 96 °. As described above, the rotation angle (absolute angle) of the motor shaft 11 can be accurately calculated by adopting the rotator 20 having different groove intervals on the left surface and the right surface.

  Next, the case where the shaft deviation of the motor shaft 11 (positional deviation of the rotating body 20) occurs will be described. 9A to 9F, the horizontal axis indicates the rotation angle, and the vertical axis indicates the detected voltage.

  As shown in FIG. 8, when the rotator 20 is displaced in the direction of arrow A, the distance between the rotator 20 and the eddy current flaw sensors 30A and 30B becomes closer, and the rotator 20 and the eddy current flaw sensor 30C are reduced. , 30D is increased. In this case, the eddy current Iw induced by the magnetic field applied from the exciting coils 31A and 31B flows on the left surface of the rotating body 20 more than usual. Therefore, as shown in the left two columns of FIG. 9A, the voltage value of the AC voltage induced in the detection coils 32A and 32B by the eddy current Iw becomes high. On the other hand, the eddy current Iw induced by the magnetic field applied from the exciting coils 31C and 31D flows on the right surface of the rotating body 20 less than usual. Therefore, as shown in the right two columns of FIG. 9A, the voltage value of the AC voltage induced in the detection coils 32A and 32B by the eddy current Iw becomes low. That is, the control device 12 causes the rotating body 20 to be displaced in the direction of arrow A when the waveform of the AC voltage induced in each of the detection coils 32A, 32B, 32C, 32D becomes the waveform shown in FIG. It is possible to detect that the axis has been shifted.

  On the other hand, when the rotating body 20 is displaced in the arrow B direction opposite to the arrow A direction, the distance between the rotating body 20 and the eddy current flaw detection sensors 30A and 30B is increased, and the rotator 20 and the eddy current flaw detection sensor are increased. The distance from 30C and 30D becomes closer. That is, as shown in FIG. 9B, the voltage value of the AC voltage induced in the detection coils 32A and 32B decreases, and the voltage value of the AC voltage induced in the detection coils 32C and 32D increases. Therefore, when the AC voltage waveform induced in each of the detection coils 32A, 32B, 32C, and 32D becomes the waveform shown in FIG. 9B, the control device 12 displaces the rotating body 20 in the arrow B direction. Can be detected.

  As shown in FIG. 8, when the rotating body 20 is misaligned (inclined) in the direction of arrow C, the distance between the rotating body 20 and the eddy current flaw detection sensors 30B and 30C is reduced. The distance from the current flaw detection sensors 30A and 30D increases. That is, as shown in FIG. 9 (c), the voltage value of the AC voltage induced in the detection coils 32B and 32C decreases, and the voltage value of the AC voltage induced in the detection coils 32A and 32D increases. Therefore, when the AC voltage waveform induced in each of the detection coils 32A, 32B, 32C, and 32D becomes the waveform shown in FIG. Can be detected.

  On the other hand, when the rotating body 20 is misaligned in the direction of arrow D opposite to the direction of arrow C, the distance between the rotating body 20 and the eddy current flaw detection sensors 30B and 30C is increased, and the rotator 20 and the eddy current flaw detection are detected. The distance to the sensors 30A and 30D is reduced. That is, as shown in FIG. 9 (d), the voltage value of the AC voltage induced in the detection coils 32B and 32C decreases, and the voltage value of the AC voltage induced in the detection coils 32A and 32D increases. Therefore, when the AC voltage waveform induced in each of the detection coils 32A, 32B, 32C, and 32D becomes the waveform shown in FIG. Can be detected.

  As shown in FIG. 8, when the rotating body 20 is displaced (displaced) in the direction of arrow E (upward) and in the direction of arrow F (downward), an eddy current Iw induced by the exciting coil 31 can flow. The area changes. For example, when the rotator 20 is displaced in the direction of arrow E on the right surface of the rotator 20, as shown in FIG. 10A, the distance between the eddy current flaw detection sensor 30C and the axis of the rotator 20 (motor shaft 11). On the other hand, the distance between the eddy current flaw detection sensor 30D and the shaft of the rotating body 20 (motor shaft 11) is increased. When the rotating body 20 is displaced in the direction of arrow F, as shown in FIG. 10B, the distance between the eddy current flaw detection sensor 30C and the axis of the rotating body 20 (motor shaft 11) is increased, while the eddy current is increased. The distance between the flaw detection sensor 30D and the shaft of the rotating body 20 (motor shaft 11) is reduced.

  Since the groove D of the rotator 20 is formed so as to extend radially from the center of the disk in a radial direction, the eddy current flaw detection sensors 30C and 30D become closer to the axis of the rotator 20 (motor shaft 11). The range in which the eddy current Iw flows becomes wider as the range in which the current Iw flows becomes narrower and is separated from the axis of the rotator 20 (closer to the edge of the rotator 20). That is, the closer the eddy current flaw detection sensors 30C and 30D are to the axis of the rotator 20, the lower the voltage value of the AC voltage induced in the detection coils 32C and 32D, and the further away from the axis of the rotator 20 is the detection coil 32C. , 32D, the voltage value of the AC voltage induced is increased. The same applies to the left surface of the rotating body 20.

  Therefore, when the rotating body 20 is misaligned in the direction of arrow E, as shown in FIG. 9E, the voltage value of the alternating voltage induced in the detection coils 32A and 32C becomes low, and the detection coils 32B and 32B, The voltage value of the alternating voltage induced in 32D becomes high. Therefore, when the AC voltage waveform induced in each of the detection coils 32A, 32B, 32C, and 32D becomes the waveform shown in FIG. Can be detected.

  On the other hand, when the rotating body 20 is misaligned in the direction of arrow F opposite to the E direction, the increasing / decreasing tendency of the AC voltage induced in each of the detection coils 32A, 32B, 32C, 32D is misaligned in the direction of arrow E. The opposite is the case. That is, as shown in FIG. 9 (f), the voltage value of the alternating voltage induced in the detection coils 32B and 32D becomes low, and the voltage value of the alternating voltage induced in the detection coils 32A and 32C becomes high. Therefore, when the AC voltage waveform induced in each of the detection coils 32A, 32B, 32C, and 32D becomes the waveform shown in FIG. Can be detected.

As described above in detail, according to the present embodiment, the following effects can be obtained.
(1) A plurality of grooves D formed on the disk surfaces on both the left and right sides of the rotator 20 with different angular intervals and extending in the radial direction, and two sets of eddy current flaw sensors 30A facing the disk surfaces, respectively. , 30B and eddy current flaw sensors 30C, 30D. Based on the AC voltage induced in each of the detection coils 32A, 32B, 32C, and 32D constituting each of the eddy current flaw detection sensors 30A, 30B, 30C, and 30D, the rotation angle of the rotating body 20 is detected, and Axis deviation can also be detected.

  (2) Since the angular interval of the groove D provided on the disk surface of the rotating body 20 is different between the left disk surface and the right disk surface, the detection coil 32A provided to face the left disk surface of the rotating body 20; It is possible to detect the rotation angle of the rotating body 20 between the adjacent grooves D from the AC voltage induced in both 32B and the detection coils 32C and 32D provided facing the disk surface on the right side of the rotating body 20. it can. For this reason, in this rotation angle detection apparatus, the absolute angle in one round (360 °) of the rotating body can be calculated.

  (3) The detection coils 32 </ b> A and 32 </ b> B are provided with the rotating shaft of the rotating body 20 interposed therebetween. Further, the detection coils 32C and 32D are also provided with the rotation axis of the rotating body 20 interposed therebetween. For this reason, if the magnitude of the voltage value (amplitude) of the alternating voltage induced in one detection coil 32A (32C) increases when the rotation axis of the rotating body 20 is inclined, the other detection coil 32B (32D). The magnitude of the voltage value of the alternating voltage induced by the voltage decreases. Thereby, the inclination of the rotating shaft of the rotating body 20 can be easily detected.

  (4) The eddy current flaw detection sensor 30B is at a position shifted by 162 ° from the position where the eddy current flaw detection sensor 30A is provided, and the eddy current flaw detection sensor 30D is at a position shifted by 195 ° from the position where the eddy current flaw detection sensor 30C is provided. Each is provided. The eddy current flaw detection sensor 30B is arranged so as to be shifted from the eddy current flaw detection sensor 30A by a quarter period of an angular interval of 72 ° of the groove D formed on the left disk surface of the rotating body 20. The eddy current flaw detection sensor 30D is arranged so as to be shifted from the eddy current flaw detection sensor 30C by a quarter cycle of the angular interval 60 ° of the groove D formed on the right disk surface of the rotating body 20. For this reason, the waveform of the alternating voltage induced in the detection coils 32A and 32B is shifted by a quarter period. Moreover, the waveform of the alternating voltage induced in the detection coils 32C and 32D is shifted by a quarter period. Therefore, the control device 12 performs two rotations of the rotating body 20 between the adjacent grooves D on the left and right surfaces of the rotating body 20 from the two sets of eddy current testing sensors 30A and 30B and the eddy current testing sensors 30C and 30D. Calculate the angle. And the control apparatus 12 can calculate the absolute angle in 1 round (360 degrees) of the rotary body 20 combining these two rotation angles.

In addition, you may change the said embodiment as follows .

In the above embodiment, the interval between the grooves D formed on the disk surfaces on both sides of the rotator 20 is a constant interval, but it is not necessarily constant.

  In the above embodiment, five grooves D are formed on the left disk surface of the rotating body 20 and six grooves D are formed on the right disk surface, but the number of grooves D is not limited to this. For example, as the number of the grooves D is increased, the resolution at which the rotation angle can be detected increases, so that the rotation angle of the rotating body 20 can be detected more finely.

  In the above embodiment, the rotation angle detection device is not limited to that provided on the motor shaft 11. For example, the present invention can be applied as long as it rotates such as a bearing or other rotating shaft.

  In the above embodiment, the disk surface on one side of the rotating body 20 may be formed flush with each other. That is, the groove D may be omitted. In this case, the eddy current flaw detection sensor facing the disk surface formed on the same plane may be omitted. Even in the case of such a configuration, the control device 12 can detect the rotation angle and the axial deviation between the adjacent grooves D of the rotating body 20.

  In the above embodiment, the eddy current flaw detection sensor 30B is arranged at a position shifted by 162 ° with respect to the eddy current flaw detection sensor 30A, and the eddy current flaw detection sensor 30C is arranged at a position shifted by 195 ° with respect to the eddy current flaw detection sensor 30A. The position where the eddy current flaw detection sensors 30B and 30C are arranged is not limited to this. What is necessary is just to arrange | position so that a phase difference may appear in the waveform which detection coil 32A and detection coil 32B, 32C output. As described in the above embodiment, in order to shift the waveform of the alternating voltage induced in the detection coils 32B and 32C and the waveform of the alternating voltage induced in the detection coil 32A by a quarter cycle, detection is performed. The coil 32B may be disposed at a position of 18 ° ± 72 ° × X (X is an integer) from the detection coil 32A, and the detection coil 32D may be disposed at a position of 15 ° ± 60 ° × X (X is an integer) from the detection coil 32C.

θ: rotation angle (absolute angle), θ1, θ2: rotation angle, D: groove, V: voltage value, Iw ... eddy current, 10 ... brushless motor, 11 ... motor shaft, 12 ... control device, 20 ... rotating body, 30, 30A, 30B, 30C, 30D ... Eddy current flaw detection sensor, 31, 31A, 31B, 31C, 31D ... Excitation coil, 32, 32A, 32B, 32C, 32D ... Detection coil.

Claims (5)

In a rotation angle detection device that detects a rotation angle of a disk-shaped rotating body that rotates integrally with a detection object as a rotation angle of the detection object,
The disk surface of the rotating body is provided with a plurality of grooves extending in the radial direction of the disk surface at angular intervals in the rotation direction,
When the rotating body rotates, a plurality of sensors that generate a signal corresponding to a magnetic field emitted from the rotating body that changes depending on the presence or absence of the groove are provided facing the disk surface,
A rotation angle detection device that obtains the rotation angle of the rotating body based on a signal generated by the sensor and detects the presence or absence of an axis deviation of the rotating body. The rotation angle detection device according to claim 1,
The first disk surface of the rotating body is provided with a plurality of grooves at first angular intervals,
A second disk surface opposite to the first disk surface is provided with a plurality of grooves at a second angular interval different from the first angular interval,
The rotation angle detection device according to claim 1, wherein a plurality of the sensors are provided to face each of the first and second disk surfaces. In the rotation angle detection device according to claim 2,
The rotation angle detection device according to claim 1, wherein the two sensors facing the first and second disk surfaces are provided on opposite sides of the rotation axis of the rotating body. In the rotation angle detection device according to claim 3,
The rotation angle detection device characterized in that an angle interval between two sensors provided across a rotation axis of the rotating body is different from an angle interval between the grooves . In the rotation angle detection apparatus as described in any one of Claims 1-4,
The rotating body is electrically conductive materials or Rannahli,
The sensor includes an exciting coil that generates an eddy current on the disk surface by applying an alternating magnetic field to the disk surface of the rotating body, and a magnetic field change caused by the eddy current generated on the disk surface of the rotating body. And a detection coil for detecting
A rotation angle detection device, wherein the rotation angle detection device is an eddy current flaw detection sensor that detects proximity of the groove based on a change in a magnetic field detected through the detection coil.

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