JP2014163816A - Magnetic encoder, robot, and mobile object - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a precise encoder at low cost.SOLUTION: A magnetic encoder includes: a revolving shaft; a disc-shaped magnet that is disposed about the revolving shaft and rotates therewith; a magnetic sensor provided so as to oppose one surface of the disc-shaped magnet; a disc-shaped first yoke formed on the opposite surface to the side having the magnetic sensor of the magnet; and a cylindrical second yoke that is formed on the outer peripheral surface of the disc-shaped magnet.

Description

  The present invention relates to a magnetic encoder, a robot, and a moving body.

  As an encoder, an optical encoder (for example, Patent Document 1) and a magnetic resolver encoder (Patent Document 2) are known.

Japanese Patent Laid-Open No. 06-269147 JP 58-162813 A

  In the optical encoder, in order to increase the resolution, it is necessary to open a slit in the disk finely, and there is a problem that the cost increases. Although the magnetic resolver encoder is low in cost, there is a problem that when the waveform of the magnetic flux is saturated, a correct phase cannot be calculated and accuracy is deteriorated. In addition, in a magnetic resolver encoder that uses a high frequency carrier signal, the carrier signal is continuously generated even when the object to be measured is stopped without rotating, so that power is wasted. was there.

  The present invention has been made to solve at least a part of the above-described conventional problems, and an object thereof is to provide an encoder with low power consumption, low cost, and high accuracy.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

(1) According to one aspect of the present invention, a magnetic encoder is provided. The magnetic encoder is provided around a rotating shaft, a disk-shaped magnet that is arranged around the rotating shaft, and rotates with the rotating shaft, and is opposed to one surface of the disk-shaped magnet. A magnetic sensor for detecting the strength of the magnetic field accompanying rotation, a disk-shaped first yoke formed on the surface of the magnet opposite to the side where the magnetic sensor is located, and a disk-shaped outer peripheral surface of the magnet A cylindrical second yoke. According to the magnetic encoder of this embodiment, the magnetic flux penetrating the magnetic sensor is only the magnetic flux generated from the surface where the first yoke and the second yoke of the magnet are not formed, so that the magnetic flux waveform is hardly saturated. . As a result, it is easy to calculate the correct phase and the accuracy can be increased. Moreover, since the magnetic flux of the magnet is detected by the magnetic sensor, a carrier signal is not required, the power consumption is low, and the cost can be facilitated.

(2) In the magnetic encoder according to the above aspect, the magnet includes two semi-disc-shaped magnets, and the two semi-disc-shaped magnets are arranged around the rotation axis, It may be magnetized in the normal direction of the joining surface of the two semi-disc shaped magnets. Since the strength of the magnetic flux of this magnet is proportional to the distance between the joint surfaces of the other magnets and the second yoke, the strength of the magnetic flux is stronger toward the center in the direction perpendicular to the magnetization direction. The edge is weaker. According to this form of magnetic encoder, the magnet magnetization strength is stronger at the center of the magnet and weaker at the end, so the magnetic flux detected by the magnetic sensor can be made a waveform close to a sine wave, and the phase can be calculated. Cheap.

(3) In the magnetic encoder according to the above aspect, the magnet includes an even number of sector-shaped magnets, and the sector-shaped magnet is magnetized in a central direction from the second yoke toward the rotation axis. The first fan-shaped magnet and the second fan-shaped magnet magnetized in the radial direction from the rotating shaft toward the second yoke may be alternately arranged around the rotating shaft.

(4) In the magnetic encoder according to the above aspect, the magnetization strength of the first sector-shaped magnet is the weakest at two boundary surfaces in contact with the second sector-shaped magnet. Strongest on a line passing through the center of the sector shape of the shape magnet, the magnetization strength of the second sector shape magnet is the weakest at the two boundary surfaces in contact with the first sector shape magnet, and the second It may be strongest on a line passing through the center of the sector shape of the sector magnet. According to this type of magnetic encoder, the magnet magnetization strength is stronger at the center of the magnet and weaker at the end, so the magnetic flux detected by the magnetic sensor can be made a waveform close to a sine wave, and the phase can be calculated. Cheap.

(5) In the magnetic encoder according to the above aspect, a nonmagnetic member may be provided between the magnet and the second yoke. According to the magnetic encoder of this form, it is possible to obtain a desired magnetic flux density foam by adjusting the magnetic flux with respect to the sensitivity characteristic of the magnetic sensor.

(6) In the magnetic encoder according to the above aspect, the magnetic sensor may have a temperature compensation function. According to the magnetic encoder of this embodiment, it is possible to suppress the influence of heat generation due to eddy current loss caused by a change in magnetic flux accompanying the rotation of the magnet.

(7) In the magnetic encoder according to the above aspect, the magnetic sensor does not saturate the output from the magnetic sensor, and the maximum value of the output from the magnetic sensor is the saturation value of the output from the magnetic sensor. It may be arranged at a position that is 90% or more. According to the magnetic encoder of this embodiment, the output from the magnetic sensor is not saturated, and the maximum value of the output from the magnetic sensor is 90% or more of the saturation value of the output from the magnetic sensor. It is possible to calculate the phase well.

(8) The magnetic encoder according to the above aspect, further comprising a third yoke on the magnetic sensor side of the disk-shaped magnet, and the thickness of the third yoke is such that the output of the magnetic encoder is saturated In addition, the maximum value of the output from the magnetic sensor may be set to such a thickness that the output from the magnetic sensor is 90% or more of the saturation value. According to the magnetic encoder of this embodiment, the thickness of the third yoke is such that the output of the magnetic encoder does not saturate, and the maximum value of the output from the magnetic sensor is the saturation value of the output from the magnetic sensor. Since the thickness is set to be 90% or more, the phase can be calculated with high accuracy.

(9) According to one aspect of the present invention, a robot is provided. This robot may include the magnetic encoder according to the above aspect, an electromechanical device having a drive shaft to which a rotation shaft of the magnetic encoder is connected, and an arm driven by the electromechanical device.

(10) According to one aspect of the present invention, a mobile object is provided. The moving body includes the magnetic encoder of the above form, an electric machine device having a drive shaft connected to a rotation shaft of the magnetic encoder, and a vehicle body that is driven by the electric machine device to move. Good.

  The present invention can be realized in various forms. For example, in addition to a magnetic encoder, an electromechanical device including a magnetic encoder, a moving body using an electromechanical device including a magnetic encoder, a robot, and the like. Can be realized in various forms.

It is explanatory drawing which shows typically the structure of the motor system which concerns on 1st Embodiment. It is explanatory drawing which shows the structure of the encoder of this embodiment. It is explanatory drawing which shows the magnetic flux by a magnet. It is explanatory drawing which expands and shows the magnetic sensor vicinity. It is explanatory drawing which shows the waveform of the output signal of the magnetic sensor in each position of the magnetic sensor of FIG. It is explanatory drawing which shows a circuit board and a magnetic sensor. It is an example of the graph which shows the output of a magnetic sensor, and the output of an encoder. It is another example of the graph which shows the output of a magnetic sensor, and the output of an encoder. It is another example of the graph which shows the output of a magnetic sensor, and the output of an encoder. It is another example of the graph which shows the output of a magnetic sensor, and the output of an encoder. It is another example of the graph which shows the output of a magnetic sensor, and the output of an encoder. It is explanatory drawing which shows a 2nd Example. It is explanatory drawing which shows the example of the output signal of the magnetic sensor in a 2nd Example. It is explanatory drawing which shows the magnet of the magnetic sensor of 3rd Embodiment. It is explanatory drawing which shows the magnet of the magnetic sensor of 4th Embodiment. It is explanatory drawing which shows the magnet of the magnetic sensor of 5th Embodiment. It is an example of the graph which shows the output of a magnetic sensor, and the output of an encoder. It is explanatory drawing which shows 6th Embodiment. It is explanatory drawing which shows the modification of 6th Embodiment. It is explanatory drawing which shows the example of how to connect an encoder and a motor. It is explanatory drawing which shows the example of how to connect an encoder and a motor. It is explanatory drawing which shows the electric bicycle (electrically assisted bicycle) which is an example of the moving body using an electromechanical device. It is explanatory drawing which shows an example of the robot using the encoder of this embodiment. It is explanatory drawing which shows an example of the double-arm 7-axis robot using the encoder of this embodiment. It is explanatory drawing which shows an example of the vertical articulated robot using the encoder of this embodiment. It is explanatory drawing which shows an example of the robot with a double arm caster using the encoder of this embodiment. It is explanatory drawing which shows the rail vehicle using the encoder of this embodiment.

First embodiment:
FIG. 1 is an explanatory diagram schematically showing the configuration of the motor system according to the first embodiment. The motor system includes a motor 100, a coupling 200, an encoder 300, a load 400, a motor drive circuit 500, and an encoder signal conversion circuit 510. The drive shaft 110 of the motor 100 is connected to the encoder 300 via the coupling 200. The encoder signal conversion circuit 510 generates encoder signals SencA and SencB using the sensor signals VA and VB of the encoder 300. The motor drive circuit 500 generates a drive signal for the motor 100 using the encoder signals SencA and SencB. The encoder signal conversion circuit 510 is a circuit independent of the encoder 300 and the motor drive circuit 500, but may be included in the encoder 300 or may be included in the motor drive circuit 500.

  FIG. 2 is an explanatory diagram illustrating a configuration of the encoder 300 according to the present embodiment. Here, a schematic diagram of a dipole magnet in which a mechanical angle (2π / rotation) and an electrical angle (2π / control angle) are paired will be described. However, an M pole magnet (M = 2 × N, where N is an integer of 1 or more. The encoder 300 includes a rotating shaft 310, a magnet 320, a side yoke 330, a back yoke 340, a circuit board 350, a magnetic sensor 360, a bearing 370, and a casing 380. The magnet 320 has a disk shape that penetrates the rotating shaft 310 at the center. A side yoke 330 is attached to one of the two circular surfaces of the magnet 320. A back yoke 340 is formed along the entire outer periphery of the magnet 320. The side yoke 330 and the back yoke 340 are formed of a soft magnetic material that allows easy passage of magnetic flux. A non-magnetic material 345 having a thickness of 0.3 to 1.0 mm may be disposed between the outer periphery of the magnet 320 and the back yoke 340. As the nonmagnetic material 345, for example, resin or aluminum can be used. By disposing the non-magnetic material 345, it is possible to adjust the lines of magnetic force from the magnet 320 with respect to the sensitivity characteristics of the magnetic sensor 360 and obtain a desired (substantially sinusoidal) magnetic flux density foam. Note that the nonmagnetic material 345 may not be disposed.

  Of the inner surface of the casing 380, a circuit board 350 is disposed on a surface opposite to the side yoke 330 with the magnet 320 interposed therebetween so as to face the magnet 320. A magnetic sensor 360 for detecting the magnetic flux of the magnet 320 is disposed on the circuit board 350. As the magnetic sensor 360, for example, an analog output Hall sensor can be used. The magnetic sensor 360 preferably includes two magnetic sensors 360A and 360B shifted by π / 2 in electrical angle in order to detect the rotation direction and phase of the magnet 320. Hereinafter, when the two magnetic sensors 360 </ b> A and 360 </ b> B are not distinguished, they are also simply referred to as a magnetic sensor 360. The magnetic sensor 360 preferably has a temperature compensation function. The rotating shaft 310 is attached to the casing 380 via a bearing 370. EM conversion circuit including at least EM conversion and communication control for receiving an electrical angle of two signals (VA (sin θ), VB (cos θ)) from magnetic sensors 360A and 360B and forming a mechanical angle signal from the electrical angle signal 365 may be provided so that the output from the EM conversion circuit 365 can be taken out by the communication line 367 and the number of poles, the number of mechanical angles, etc. can be set and read in addition to the mechanical angle in communication control.

  FIG. 3 is an explanatory diagram showing the magnetic flux generated by the magnet 320. FIG. 3A is an explanatory view showing a state in which the magnet 320 is viewed from the circuit board 350 side. FIG. 3B is an explanatory view showing a BB cut surface of the magnet 320 of FIG. The magnet 320 includes two semicircular magnets 320A and 320B. When the two magnets 320A and 320B are not distinguished from each other, they are also simply referred to as magnets 320. As shown in FIG. 3A, the two magnets 320A and 320B are magnetized in parallel in a direction perpendicular to the joint surfaces of the two magnets 320A and 320B, as indicated by the magnetic flux φ1 indicated by a broken line. In FIG. 3A, a magnetic flux φ1 indicated by a broken line indicates a magnetic flux inside the magnets 320A and 320B. In the back yoke 340 on the outer periphery of the magnet 320, as can be seen from FIGS. 3A and 3B, on the magnet 320A side, the magnetic flux φ2 passing through the back yoke 340 is the side from the circuit board 350 (FIG. 2) side. It faces the direction toward the yoke 330. On the other hand, on the magnet 320B side, the magnetic flux φ3 passing through the back yoke 340 is directed in the direction from the side yoke 330 side toward the circuit board 350 (FIG. 2).

  In FIG. 3 (B), the magnetic flux φ4 emitted to the side yoke 330 side of the magnet 320 (320A, 320B) is directed along the back yoke 340 in the direction opposite to the direction of the magnetic flux φ1. Magnetic flux φ5 emitted from the N pole of the magnet 320A to the circuit board 350 side enters the S pole of the magnet 320B. Further, the magnetic flux φ6 emitted from the N pole of the magnet 320B enters the S pole of the magnet 320A. The magnetic fluxes φ1, φ5, φ1, and φ6 constitute one closed curve from the characteristics of the magnetic flux.

  The strength of the magnetic flux φ1 inside the magnets 320A and 320B is stronger at the center and weaker at the end in the direction perpendicular to the magnetization direction. Therefore, the strength of the magnetic flux φ5 outside the magnets 320A and 320B is also stronger at the center and weaker at the end in the direction perpendicular to the magnetization direction of the magnets 320A and 320B (the left-right direction in FIG. 3A).

  According to the present embodiment, the magnetic flux from the back yoke 340 side of the magnet 320 passes through the back yoke 340 and further passes through the side yoke 330. Therefore, the magnetic flux that passes through the magnetic sensor 360 is only the magnetic flux φ5 that is emitted from the surface of the magnet 320 opposite to the side yoke 330. The strength of the magnetic flux φ5 is stronger at the center and weaker at the end in the direction perpendicular to the magnetization direction of the magnets 320A and 320B. Therefore, the strength of the magnetic field detected by the magnetic sensor 360 shows a wavy change that changes according to the rotational positions of the magnets 320A and 320B.

  FIG. 4 is an explanatory view showing the vicinity of the magnetic sensor 360 in an enlarged manner. FIG. 4A shows an example in which the magnetic sensor 360A is arranged at the outermost position among the positions where the magnetic sensor 360A can be arranged on the circuit board 350. FIG. 4C shows an example in which the magnetic sensor 360A is arranged at the innermost position among the positions where the magnetic sensor 360A of the circuit board 350 can be arranged. FIG. 4B shows an example in which the magnetic sensor 360A is arranged between the arrangement position in FIG. 4A and the arrangement position in FIG. 4C.

  FIG. 5 is an explanatory diagram showing the waveform of the output signal VA of the magnetic sensor 360A at each position of the magnetic sensor 360A of FIG. 5A, 5B, and 5C correspond to FIGS.4A, 4B, and 4C, respectively, and the output signal VA of the magnetic sensor 360A is from 0. Transition is made between VDD (the operating voltage of the magnetic sensor 360A), but in FIGS. 5A, 5B, and 5C, it is normalized between −1 and 1.

  The waveform of the output signal VA of the magnetic sensor 360A varies depending on the relative positional relationship between the magnets 320A and 320B and the magnetic sensor 360A. That is, in the present embodiment, when arranged at the position shown in FIG. 4B, the waveform of the output signal VA of the magnetic sensor 360A is a waveform that is almost similar to a sine wave. On the other hand, when arranged at the position shown in FIG. 4A, the waveform of the output signal VA of the magnetic sensor 360A is saturated, and the top and bottom vertices are flattened. In addition, when the magnetic sensor 360A is arranged at the position shown in FIG. 4C, the output signal VA of the magnetic sensor 360A has a waveform almost similar to a sine wave, but the magnitude of the output signal VA peak of the magnetic sensor 360 is large. This is smaller than the peak size of the output signal VA of the magnetic sensor 360A when the magnetic sensor 360A is arranged at the position shown in FIG. The magnetic sensor 360A is preferably arranged at a position where the output signal VA of the magnetic sensor 360A does not saturate and can output the output signal VA having the largest peak. That is, in this embodiment, it is preferable to arrange the magnetic sensor 360B at the position shown in FIG. However, since the waveform of the output signal VA of the magnetic sensor 360A changes depending on the relative positional relationship between the magnet 320 and the magnetic sensor 360 in this way, for example, the position shown in FIG. There may be a case where the output signal VA of the magnetic sensor 360A is not saturated at the position shown in FIG. Therefore, it is preferable to adopt a configuration in which the magnetic sensor 360A can be moved from the center to the radial direction on the circuit board 350, and to adjust the installation position of the magnetic sensor based on the output signal VA of the actual magnetic sensor 360A. . For example, the magnetic sensor 360A may be arranged so that the magnitude of the output signal VA from the magnetic sensor 360A is 90% or more of the saturation value. The same applies to the magnetic sensor 360B.

  FIG. 6 is an explanatory diagram showing the circuit board 350 and the magnetic sensor 360A. In this embodiment, a surface mount type magnetic sensor 360A is used as the magnetic sensor 360A. The magnetic sensor 360A has three mounting terminals 361 (a power supply terminal, a ground terminal, and an output signal terminal). As the surface mount type magnetic sensor 360A, a SOP (Small Outline Package) type in which the mounting terminal 361 is flat or a SOJ (mall Outline J-leaded) type magnetic sensor 360A in which the mounting terminal 361 is bent into a J-shape is adopted. can do. The circuit board 350 includes a conductor pattern 351 for mounting mounting terminals of the magnetic sensor 360A.

  The magnetic sensor 360A can be mounted on the circuit board 350 as follows. First, the solder 353 is arranged on the conductor pattern 351 of the circuit board 350 by printing. Next, the magnetic sensor 360 </ b> A is disposed on the circuit board 350 so that the mounting terminals 361 of the magnetic sensor 360 </ b> A are in contact with the conductor pattern 351. At this stage, the circuit board 350 and the magnetic sensor 360A are not mounted by solder. The mounting terminals 361 of the magnetic sensor 360A are preferably pre-soldered. Next, the circuit board 350 on which the magnetic sensor 360A is mounted is heated by passing through a reflow furnace. As a result, the solder 353 is melted, and the conductor pattern 351 and the mounting terminals 361 of the magnetic sensor 360 </ b> A are mounted by the solder 353. Note that the magnetic sensitivity characteristics of the magnetic sensor 360A can be changed by moving the magnetic sensor 360A up and down with respect to the conductor pattern 351 to set the position. The same applies to the magnetic sensor 360B.

FIG. 7 is an example of a graph showing the output of the magnetic sensor and the output of the encoder. The outputs of the magnetic sensors 360A and 360B are analog signals of 0 to VDD. The encoder signal conversion circuit 510 uses the output VA of the magnetic sensor 360A and the output VB of the magnetic sensor 360B to set n when the electrical angle is 0 and 256 when the electrical angle is 2π (n is 2 or more). Encoder output SencA. The value S1 represents the electrical angle of the magnet 320A using a resolution of 1/2 ⁿ (for example, 1/256). It is possible to calculate the mechanical angle θm1 (0 to 2π) from the value S1. Further, the rotation direction of the rotation shaft 310 is calculated from the output VA of the magnetic sensor 360A and the output VB of the magnetic sensor 360B. For example, when the output VB of the magnetic sensor 360B is a negative value, when the output VA of the magnetic sensor 360A increases, it is determined as normal rotation, and when the output VB of the magnetic sensor 360B is a positive value, the magnetic sensor 360A When the output VA increases, it is determined that the rotation is reverse.

  FIG. 8 is another example of a graph showing the output of the magnetic sensor and the output of the encoder. The encoder signal conversion circuit 510 outputs an encoder output signal SencA that is a digital signal from the output VA of the magnetic sensor 360A. The encoder output signal SencA is an n-bit (for example, 8 bits) digital signal that simulates the output VA of the magnetic sensor 360A into a triangular wave. The encoder signal conversion circuit 510 outputs an encoder output signal SencB that is a digital signal from the output VB of the magnetic sensor 360B. The encoder output signal SencB is obtained by making the output VB of the magnetic sensor 360B a binary rectangular wave of 0 and 1 with VDD / 2 as a determination value. In this example, the mechanical angle at which the value of the encoder output signal SencA is S2 can be considered as two types of θm2 and θm2 ′, but one of them is determined depending on whether the value of the encoder output signal SencB is 0 or 1. Is possible.

  FIG. 9 is another example of a graph showing the output of the magnetic sensor and the output of the encoder. In FIG. 8, the encoder output signal SencA is a triangular wave n-bit (for example, 8 bits) digital signal in FIG. 8, but in FIG. 9, the encoder output signal SencA is an approximately sine wave of n bits (for example, 8 bits). The difference is that it is a digital signal. In this example, there are two possible mechanical angles, θm3 and θm3 ′, at which the value of the encoder output signal SencA is S3, but one of them is determined depending on whether the value of the encoder output signal SencB is 0 or 1. Is possible.

  FIG. 10 is another example of a graph showing the output of the magnetic sensor and the output of the encoder. In FIG. 9, the encoder output signal SencB is a binary rectangular wave of 0 and 1, but in FIG. 10, the encoder output signal SencB is made up of n bits (e.g., 8 bits) of a substantially sine wave like the encoder output signal SencA. ) Is different from the digital signal. In this example, there are two possible mechanical angles, θm4 and θm4 ′, where the value of the encoder output signal SencA is S4A. In this example, the mechanical angle where the value of the encoder output signal SencB is S4B is θm4. There are two possible ways of θm4 ″. The mechanical angle that satisfies both. It can be determined as θm4.

  FIG. 11 is another example of a graph showing the output of the magnetic sensor and the output of the encoder. The encoder output signals SencA and SencB are pulses having a width obtained by dividing the electrical angle 2π by the resolution. The encoder output signals SencA and SencB are out of phase by π / 2, similar to the outputs VA and VB of the magnetic sensors 360A and 360B. Since this encoder output is the same as the output of the optical encoder, when the motor drive circuit 500 is of a type in which the output of the optical encoder is input, the output of the encoder signal conversion circuit 510 can be input as it is. .

  As described above, according to the first embodiment, the magnetic flux passing through the magnetic sensor 360 is only the magnetic flux φ5 emitted from the surface of the magnet 320 opposite to the side yoke 330, and the output signal VA of the magnetic sensor 360A is obtained. It becomes difficult to saturate, it is possible to obtain a smooth waveform that can determine the rotational position with high resolution, and it becomes possible to measure an electrical angle with high accuracy.

Second embodiment:
FIG. 12 is an explanatory diagram showing the second embodiment. FIG. 13 is an explanatory diagram showing an example of the output signal VA of the magnetic sensor 360A in the second embodiment. Compared with the first embodiment, the second example is a second side yoke 390 formed of a soft magnetic material on the surface of the magnets 320A and 320B between the magnets 320A and 320B and the magnetic sensor 360A. Is different. 12A, 12B, and 12C, the number of second side yokes 390 is different. That is, in the example shown in FIG. 12A, the number of second side yokes 390 is one, the example shown in FIG. 12B is two, and the example shown in FIG. It is a sheet. 13A, 13B, and 13C correspond to FIGS. 12A, 12B, and 12C, respectively. Similar to the side yoke 330, the second side yoke 390 can easily pass a magnetic flux. Therefore, the larger the number of second side yokes 390, the easier the magnetic flux passes through the second side yoke 390. That is, as the number of the second side yokes 390 increases, the magnetic flux emitted from the second side yoke 390 to the magnetic sensor 360 side decreases. As a result, when the number of the second side yokes 390 increases in the order of (B) and (C) from FIG. 12 (A), as shown in the order of (B) and (C) of FIG. The waveform of the output signal VA of the magnetic sensor 360A is almost a sine wave, but the peak height gradually decreases. In this embodiment, when the number of second side yokes 390 is one, adjustment is made so that the waveform of the output signal VA of the magnetic sensor 360A is not saturated. Therefore, when the second side yoke 390 shown in FIG. 12 (A) is made into one sheet or a magnetic member thinner than the second side yoke 390 shown in FIG. 12 (A) is used, the magnetic sensor The waveform of the output signal VA of 360A is saturated as shown in FIG. 5A.

  In this embodiment, the waveform of the output signal VA of the magnetic sensor 360 is further increased by making the second side yoke 390 as thick as possible, selecting the high sensitivity type of the magnetic sensor 360A, and adjusting the solder mounting position. It is preferable that fine adjustment is possible. Further, the thickness of the second side yoke 390 may be changed instead of the number of the second side yokes 390. Further, all the second side yokes 390 need not have the same thickness, and the thickness is changed for each second side yoke 390, such as 0.1 mm, 0.2 mm, and 0.4 mm. You may combine the magnetic body member from which thickness differs.

  As described above, according to the second embodiment, by changing the number (thickness) of the second side yokes 390, the output signal VA of the magnetic sensor 360A is less likely to be saturated and can have a clean waveform. It becomes possible to measure the electrical angle with high accuracy.

Third embodiment:
FIG. 14 is an explanatory diagram illustrating a magnet of the magnetic sensor according to the third embodiment. The magnets 320A and 320B of the third embodiment have different magnetization directions from the magnets 320A and 320 of the first embodiment. In the first embodiment, the magnets 320A and 320B are magnetized in parallel, whereas in the third embodiment, the magnet 320A is magnetized from the rotating shaft 310 toward the back yoke 340. The magnet 320B is magnetized from the back yoke 340 toward the rotating shaft 310. Such magnetization is called radial magnetization.

  In the magnetic sensor of the third embodiment, the output signal VA of the magnetic sensor 360A and the output signal VB of the magnetic sensor 360B are not necessarily sine waves, but the output signals VA and VB are out of phase by π / 2. If the relationship between the electrical angle θ and the output signals VA and VB is measured in advance, the electrical angle θ can be uniquely determined from the output signals VA and VB.

  As described above, even when the magnets 320 </ b> A and 320 </ b> B are magnetized as in the magnetic sensor of the third embodiment, the magnetic flux passing through the magnetic sensor 360 is only the magnetic flux φ <b> 5 emitted from the surface opposite to the side yoke 330 of the magnet 320. Therefore, it is difficult to saturate the output signal VA of the magnetic sensor 360A, and the electrical angle can be measured with high accuracy.

Fourth embodiment:
FIG. 15 is an explanatory diagram illustrating a magnet of the magnetic sensor according to the fourth embodiment. The magnets 320A and 320B of the magnetic sensor of the fourth embodiment have the same magnetization direction as the magnets 320A and 320B of the magnetic sensor of the third embodiment, but are different in magnitude of magnetization. In the magnetic sensor of the third embodiment, the magnets 320A and 320B are magnetized at the same size everywhere, but in the magnetic sensor of the fourth embodiment, the closer to the joining surface of the two magnets, Weakly magnetized. The magnetization intensity of the magnet 320A is the weakest at the interface in contact with the magnet 320B and the strongest on the line passing through the center P of the magnet 320A. In addition, it may be said to be on a line passing through the midpoint Q of the arc. The same applies to the magnet 320B.

  In the magnetic sensor of the fourth embodiment, the output signal VA of the magnetic sensor 360A and the output signal VB of the magnetic sensor 360B are close to a sine wave as compared to the third embodiment. Further, by adjusting the strength of magnetization, the output signal VA of the magnetic sensor 360A and the output signal VB of the magnetic sensor 360B can be made closer to a sine wave. The output signals VA and VB are not sine waves, but are signals that are out of phase by π / 2. If the relationship between the electrical angle θ and the output signals VA and VB is measured in advance, the output signals It is possible to uniquely determine the electrical angle θ from VA and VB.

  As described above, even when the magnets 320 </ b> A and 320 </ b> B are magnetized as in the magnetic sensor of the fourth embodiment, the magnetic flux passing through the magnetic sensor 360 is only the magnetic flux φ <b> 5 emitted from the surface of the magnet 320 opposite to the side yoke 330. Therefore, it is difficult to saturate the output signal VA of the magnetic sensor 360A, and the electrical angle can be measured with high accuracy.

Fifth embodiment:
FIG. 16 is an explanatory diagram illustrating a magnet of the magnetic sensor according to the fifth embodiment. In the magnetic sensors of the first to fourth embodiments, the case where the magnet 320 is configured by two magnets 320A and 320B has been described as an example. However, the number of magnets constituting the magnet 320 is four or eight. Or an even number of 2 or more. In the example shown in FIG. 16A, the magnet 320 is composed of four magnets, and in the example shown in FIG. 16B, the magnet 320 is composed of eight magnets. Magnetization of the magnet 320 may be parallel magnetization as in the first embodiment or radial magnetization as in the third embodiment.

  FIG. 17 is an example of a graph showing the output of the magnetic sensor and the output of the encoder. The outputs of the magnetic sensors 360A and 360B are analog signals of 0 to VDD. The encoder signal conversion circuit 510 uses the output VA of the magnetic sensor 360A and the output VB of the magnetic sensor 360B to set the 10-bit encoder output SencA to 0 when the electrical angle is 0 and 1024 when the electrical angle is 8π. Output. The upper 2 bits are a value counted every 2π of the output VA of the magnetic sensor 360A. The value S6 represents the electrical angle (0 to 8π) of the magnet 320A using a resolution (for example, 1024). The mechanical angle θm6 can be calculated from the value S6. Further, the rotation direction of the rotation shaft 310 is calculated from the output VA of the magnetic sensor 360A and the output VB of the magnetic sensor 360B. For example, when the output VB of the magnetic sensor 360B is a negative value, when the output VA of the magnetic sensor 360A increases, it is determined as normal rotation, and when the output VB of the magnetic sensor 360B is a positive value, the magnetic sensor 360A When the output VA increases, it is determined that the rotation is reverse.

  As described above, according to the fifth embodiment, the mechanical angle of the encoder 300 can be easily calculated even if the number is an even number of 2 or more. Instead of FIG. 17, the same correspondence relationship as in FIGS. 8 to 11 may be used.

Sixth embodiment:
FIG. 18 is an explanatory diagram showing the sixth embodiment. In the first to fifth embodiments, the magnetization direction of the magnet 320 is a direction perpendicular to the rotation shaft 310 or a torsion direction. In the sixth embodiment, the magnetization direction of the magnet is Is different in that the direction is parallel to the rotation axis 310. Also in the sixth embodiment, the magnetic flux passing through the magnetic sensor 360 is only the magnetic flux φ5 coming out from the surface of the magnet 320 on the side opposite to the side yoke 330, which makes it difficult to saturate the output signal VA of the magnetic sensor 360A. Can be made a smooth waveform that can be determined with high resolution, and an accurate electrical angle can be measured. The magnetic flux φ5 is normal to the plane including the boundary surface between the two magnets 320.

  FIG. 19 is an explanatory diagram showing a modification of the sixth embodiment. FIG. 19A shows a case where the number of magnets 320 is four, and FIG. 19B shows a case where the number of magnets 320 is eight. Note that the letters N and S attached to the magnet 320 indicate the magnetic poles on the magnetic sensor 360 side. According to these modified examples, the mechanical angle of the encoder 300 can be calculated as in the fifth embodiment.

  FIG. 20 is an explanatory diagram showing an example of how to connect the encoder 300 and the motor 100. The rotating shaft 311 of the encoder 300 has a chuck in which one end 312 is divided into three. The end 312 has a male screw 313. A nut 315 having a female screw 314 is disposed around the rotation shaft 311. By inserting the drive shaft 110 of the motor 100 into the end 312 and turning the nut 315, the chuck can be tightened to fix the rotary shaft 311 of the encoder 300 and the drive shaft 110 of the motor 100.

  FIG. 21 is an explanatory diagram showing an example of how to connect the encoder 300 and the motor 100. In this connection, the rotary shaft 316 of the encoder 300 and the drive shaft 110 of the motor 100 are connected by a screw 317. The direction of the screw 317 is preferably selected as a normal screw or a reverse screw so that the screw 317 is tightened more when the rotary shaft 316 is rotated. A heat insulating material 600 is inserted between the motor 100 and the encoder 300, and an air layer 610 is formed between the drive shaft 110 of the motor 100 and the casing 380 of the encoder 300. Thereby, it is possible to prevent heat from being transmitted to the circuit board 350.

  The encoder described in the above embodiment can be applied as an encoder connected to an electric mobile body, an electric mobile robot, or a drive device of a medical device, as shown below.

  FIG. 22 is an explanatory diagram showing an electric bicycle (electric assist bicycle) that is an example of a moving body using an electromechanical device. This bicycle 3300 is provided with a motor 3310 with an encoder as a driving unit on a front wheel, and a control circuit 3320 and a rechargeable battery 3330 are provided on a frame below the saddle. The motor with encoder 3310 assists traveling by driving the front wheels using the power from the rechargeable battery 3330. In addition, the electric power regenerated by the motor of the encoder-equipped motor 3310 is charged in the rechargeable battery 3330 during braking. The control circuit 3320 is a circuit that controls driving and regeneration of the motor portion of the motor 3310 with encoder and shifting of the transmission device portion.

  FIG. 23 is an explanatory diagram showing an example of a robot using the encoder of the present embodiment. The robot 3400 includes first and second arms 3410 and 3420 and a motor 3430 with an encoder. The motor with encoder 3430 is used when the second arm 3420 as a driven member is rotated horizontally. As the motor with encoder 3430, the motor 100 to which the encoder described in this embodiment is connected may be used.

  FIG. 24 is an explanatory diagram showing an example of a double-armed 7-axis robot using the encoder of the present embodiment. The double-arm 7-axis robot 3450 includes a joint motor 3460, a gripper motor 3470, an arm 3480, and a gripper 3490. The joint motor 3460 is disposed at a position corresponding to a joint portion such as a shoulder joint, an elbow joint, or a wrist joint. The joint motor 3460 includes two motors for each joint in order to move the arm 3480 and the grip portion 3490 in a three-dimensional manner. In addition, the gripper motor 3470 opens and closes the gripper 3490 and causes the gripper 3490 to grip an object. In the double-arm 7-axis robot 3450, the motor 100 to which the encoder 300 described in the present embodiment is connected may be used as the joint motor 3460 or the gripping motor 3470.

  FIG. 25 is an explanatory diagram showing an example of a vertical articulated robot using the encoder of the present embodiment. As shown in FIG. 25, the vertical articulated robot 3640 includes a main body portion 3641, an arm portion 3642, a robot hand 3645, and the like. The main body 3641 is fixed on, for example, a floor, a wall, a ceiling, or a movable carriage. The arm portion 3642 is provided movably with respect to the main body portion 3641. The main body portion 3641 has a drive unit (not shown) that generates power for rotating the arm unit 3642, and a control unit that controls the drive unit. Etc. are built-in. As the drive unit, the motor 100 including the encoder 300 described in the present embodiment may be used.

  The arm portion 3642 includes a first frame 3642a, a second frame 3642b, a third frame 3642c, a fourth frame 3642d, and a fifth frame 3642e. The first frame 3642a is connected to the main body 3641 so as to be rotatable or refractable via a rotational refraction axis. The second frame 3642b is connected to the first frame 3642a and the third frame 3642c via a rotational refraction axis. The third frame 3642c is connected to the second frame 3642b and the fourth frame 3642d via a rotational refraction axis. The fourth frame 3642d is connected to the third frame 3642c and the fifth frame 3642e via the rotational refraction axis. The fifth frame 3642e is connected to the fourth frame 3642d via the rotational refraction axis. The arm portion 3642 is configured such that each frame 3642a, 3642b, 3642c, 3642d, 3642e moves while being rotated or refracted around each rotational refraction axis under the control of a control portion (not shown).

  A hand connection portion 3634 is connected to the side of the arm portion 3642 opposite to the side on which the fourth frame 3642d is provided in the fifth frame 3642e, and a robot hand 3645 is attached to the hand connection portion 3634.

  The robot hand 3645 includes a base 3645a and a finger 3645b connected to the base 3645a. The motor 100 including the encoder 300 described in the present embodiment is incorporated in a connection portion between the base portion 3645a and the finger portion 3645b and each joint portion of the finger portion 3645b. When these motors 100 are driven, the finger portion 3645b is bent and an object can be gripped. These motors 100 are ultra-small motors, and can realize a robot hand 3645 that reliably holds an object while being small. Accordingly, it is possible to provide a highly versatile robot that can perform a complex operation using the small and lightweight robot hand 3645.

  FIG. 26 is an explanatory diagram showing an example of a robot with a double-arm caster using the encoder 300 described in the present embodiment. As shown in FIG. 26, the robot 3762 with a two-arm caster includes a vehicle body portion 3763. The vehicle body portion 3763 includes a vehicle body main body 3763a, and four wheels 3763b are installed on the ground side of the vehicle body main body 3763a. The vehicle body 3763a has a built-in rotation mechanism that drives the wheels 3763b. Further, a control unit 3764 for controlling the posture and operation of the robot 3762 with a double-arm caster is built in the vehicle body 3763a.

  A main body rotating portion 3765 and a main body portion 3766 are stacked on the vehicle body main body 3766a in this order. The main body rotation unit 3765 is provided with a rotation mechanism that rotates the main body unit 3766. The main body 3766 rotates about the vertical direction as the center of rotation. A pair of imaging devices 3767 is installed on the main body 3766, and the imaging device 3767 images the periphery of the robot 3762 with a double-arm caster. Then, the distance between the photographed object and the imaging device 3767 can be detected.

  A left arm portion 3768 and a right arm portion 3769 are installed on two opposing surfaces of the side surface of the main body portion 3766. Each of the left arm portion 3768 and the right arm portion 3769 includes an upper arm portion 3770, a lower arm portion 3771, and a hand portion 3772 as movable portions. The upper arm portion 3770, the lower arm portion 3771, and the hand portion 3772 are connected so as to be rotatable or bendable. The main body 3766 includes a rotation mechanism 3773 that rotates the upper arm 3770 with respect to the main body 3766. The upper arm portion 3770 includes a rotation mechanism 3773 that rotates the lower arm portion 3771 with respect to the upper arm portion 3770. The lower arm portion 3771 includes a rotation mechanism 3773 that rotates the hand portion 3772 with respect to the lower arm portion 3771. Further, the lower arm portion 3771 incorporates a rotation mechanism 3773 that twists with the longitudinal direction of the lower arm portion 3771 as the rotation axis.

  The hand portion 3772 includes a hand main body 3772a and a gripping portion 3772b as a pair of plate-like movable portions located at the tip of the hand main body 3772a. The hand main body 3772a incorporates a linear motion mechanism 3774 that moves the gripping portion 3772b to change the interval between the gripping portions 3772b. The hand portion 3772 can grip an object to be gripped by opening and closing the grip portion 3772b.

  The rotation mechanism 3773 and the linear motion mechanism 3774 are provided with the motor 100 including the encoder 300 described in the present embodiment. Therefore, the rotation mechanism 3773 can smoothly change the rotation direction without rattling even when the rotation direction is reversed. The linear motion mechanism 3774 can smoothly change the movement direction without rattling even when the movement direction is reversed. Therefore, the robot 3762 with a double arm caster can move the left arm portion 3768 and the right arm portion 3769 with high positional accuracy.

  Further, the rotating mechanism that rotates the wheel 3763b and the rotating mechanism that rotates the main body 3766 incorporate the motor 100 including the encoder 300 described in the present embodiment. Therefore, the robot 3762 with a two-arm caster can be rotated without rattling even when the traveling direction is changed. And the robot 3762 with a double-arm caster can be rotated without rattling even when the rotation direction of the main body 3766 is changed.

  FIG. 27 is an explanatory diagram showing a railway vehicle using the encoder 300 of the present embodiment. The railway vehicle 3500 includes a motor 3510 with an encoder and wheels 3520. The encoder-equipped motor 3510 drives the wheel 3520. Furthermore, the motor with encoder 3510 is used as a generator when the railway vehicle 3500 is braked to regenerate electric power. As the motor with encoder 3510, the motor 100 including the encoder 300 described in this embodiment may be used.

  The embodiments of the present invention have been described above based on some embodiments. However, the embodiments of the present invention described above are for facilitating the understanding of the present invention and limit the present invention. It is not a thing. The present invention can be changed and improved without departing from the spirit and scope of the claims, and it is needless to say that the present invention includes equivalents thereof.

    DESCRIPTION OF SYMBOLS 100 ... Motor 110 ... Drive shaft 200 ... Coupling 300 ... Encoder 310 ... Rotating shaft 311 ... Rotating shaft 312 ... End part 313 ... Male screw 314 ... Female screw 315 ... Nut 316 ... Rotating shaft 317 ... Screw 320, 320A, 320B ... Magnet 330 ... Side yoke 340 ... Back yoke 350 ... Circuit board 351 ... Conductor pattern 353 ... Solder 360, 360A, 360B ... Magnetic sensor 361 ... Mounting terminal 370 ... Bearing 380 ... Casing 390 ... Second side yoke 400 ... Load 500 ... Motor drive circuit 510 ... Encoder signal conversion circuit 600 ... Heat insulating material 610 ... Air layer 3300 ... Bicycle 3310 ... Motor with encoder 3320 ... Control circuit 3330 ... rechargeable battery 3400 ... robot 3410 ... second arm 3420 ... second arm 3430 ... motor with encoder 3450 ... double-arm 7-axis robot 3460 ... joint motor 3470 ... gripping motor 3480 ... arm 3490 ... gripping part 3500 ... railcar 3510 ... Motor with encoder 3520 ... Wheel 3640 ... Vertical articulated robot 3641 ... Main body part 3642 ... Arm part 3642a ... First frame 3642b ... Second frame 3642c ... Third frame 3642d ... Fourth frame 3642e ... Fifth frame 3643 ... Hand Connection part 3645 ... Robot hand 3645a ... Base part 3645b ... Finger part 3762 ... Robot with double-arm casters 3763 ... Car body part 3763a ... Car Main body 3763b ... wheel 3764 ... control unit 3765 ... main body rotation unit 3766 ... main body unit 3767 ... imaging device 3768 ... left arm unit 3769 ... right arm unit 3770 ... upper arm unit 3771 ... lower arm unit 3772 ... hand unit 3772b interval ... grip unit 3772a ... hand Main body 3772b ... gripping portion 3773 ... rotating mechanism 3774 ... linear motion mechanism

Claims (10)

A magnetic encoder,
A rotation axis;
A disc-shaped magnet disposed around the rotation axis and rotating together with the rotation axis;
A magnetic sensor that is provided opposite to one surface of the disk shape of the magnet and detects the strength of the magnetic field accompanying the rotation of the magnet;
A disk-shaped first yoke formed on a surface of the magnet opposite to the side on which the magnetic sensor is located;
A cylindrical second yoke formed on the disk-shaped outer peripheral surface of the magnet;
A magnetic encoder. The magnetic encoder according to claim 1, wherein
The magnet includes two semi-disc shaped magnets,
The magnetic encoder, wherein the two semi-disc shaped magnets are magnetized in a normal direction of a joint surface of the two semi-disc shaped magnets when arranged around the rotation axis. The magnetic encoder according to claim 1, wherein
The magnet includes an even number of fan-shaped magnets,
The sector-shaped magnet includes a first sector-shaped magnet magnetized in a central direction from the second yoke toward the rotation axis, and a first magnet magnetized in a radial direction from the rotation axis toward the second yoke. A magnetic encoder in which two fan-shaped magnets are alternately arranged around the rotation axis. The magnetic encoder according to claim 3,
The strength of magnetization of the first sector magnet is the weakest at the two boundary surfaces in contact with the second sector magnet, and is the strongest on a line passing through the center of the sector of the first sector magnet. ,
The strength of magnetization of the second sector-shaped magnet is the weakest at the two boundary surfaces in contact with the first sector-shaped magnet and the strongest on the line passing through the center of the sector shape of the second sector-shaped magnet. , Magnetic encoder. In the magnetic encoder according to any one of claims 1 to 4,
A magnetic encoder comprising a non-magnetic member between the magnet and the second yoke. In the magnetic encoder according to any one of claims 1 to 5,
The magnetic sensor is a magnetic encoder having a temperature compensation function. The magnetic encoder according to any one of claims 1 to 6,
The magnetic sensor is disposed at a position where the output from the magnetic sensor does not saturate and the maximum value of the output from the magnetic sensor is 90% or more of the saturation value of the output from the magnetic sensor, Magnetic encoder. In the magnetic encoder according to any one of claims 1 to 7,
Furthermore, a third yoke is provided on the magnetic sensor side of the disk-shaped magnet,
The thickness of the third yoke is such that the output of the magnetic encoder is not saturated and the maximum value of the output from the magnetic sensor is 90% or more of the saturation value of the output from the magnetic sensor. This is a magnetic encoder. A magnetic encoder according to any one of claims 1 to 8,
An electromechanical device having a drive shaft connected to the rotary shaft of the magnetic encoder;
An arm driven by the electromechanical device;
Robot equipped with. A magnetic encoder according to any one of claims 1 to 8,
An electromechanical device having a drive shaft connected to the rotary shaft of the magnetic encoder;
A vehicle body driven and moved by the electromechanical device;
A moving object comprising:

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