JP2010066141A - Rotation detector and bearing provided with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rotation detector having a simple structure and for detecting an absolute angle with high accuracy, and a bearing mounted with this rotation detector. <P>SOLUTION: The rotation detector 1 includes: a plurality of magnetic encoders 2A and 2B, which are provided on the surface of the same ring-shaped core metal 12 concentrically with this core metal 12, and have magnetic poles different in number from each other; a plurality of magnetic sensors 3A and 3B for respectively detecting magnetic fields of these individual magnetic encoders 2A and 2B; and an angle calculation means 19 for finding absolute angles of the magnetic encoders 2A and 2B based on magnetic-field signals detected by these individual magnetic sensors 3A and 3B. In the core metal 12, a ring-shaped bent part 12aa projecting into the shape of a folded-back piece to the surface side where these individual magnetic encoders 2A and 2B are provided, between the individual magnetic encoders 2A and 2B adjoining mutually. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a rotation detection device used for rotation angle detection in various devices, particularly rotation angle detection for rotation control of various motors, and a bearing with a rotation detection device equipped with the rotation detection device.

  As this type of rotation detection device, for example, a ring-shaped magnetic pulse generating means such as a magnetic encoder in which magnetic pole pairs are arranged in the circumferential direction for generating magnetic pulses, and a substantially linear shape in the circumferential direction with respect to the magnetic pulse generating means And a plurality of magnetic sensor elements that detect the magnetic pulse, and an absolute angle is detected by calculating an output signal of the magnetic sensor element (for example, Patent Documents 1 and 2). ).

As another rotation detection device, a magnetic drum having two magnetic encoders having different numbers of magnetic pole pairs per one rotation and two magnetic sensors for detecting the magnetic field of each magnetic encoder are provided, and the magnetic sensor detects 2 There has also been proposed an apparatus that detects an absolute angle based on a phase difference between magnetic field signals of two magnetic encoders (for example, Patent Document 3).
JP-T-2001-518608 Special Table 2002-541485 Japanese Patent Laid-Open No. 06-058766

However, with the above-described rotation detection device, it is difficult to detect an absolute angle with high resolution from the magnetic encoder.
Therefore, in the rotation detection device disclosed in Patent Document 3, a magnetic sensor having a function of detecting position information within the magnetic pole of the magnetic encoder as in the rotation detection devices disclosed in Patent Documents 1 and 2 is used. It is conceivable to detect an absolute angle with high resolution.

However, in the rotation detection device configured as described above, when a plurality of magnetic sensors and an arithmetic processing circuit are integrated on the same semiconductor chip, let's narrow the interval between the magnetic sensors by arranging two magnetic encoders adjacent to each other. Then, the magnetic patterns of both magnetic encoders interfere with each other, and the angle detection accuracy deteriorates. As a result, the phase difference for calculating the absolute angle cannot be obtained accurately, and the absolute angle calculation error increases.
The above problem can be solved by widening the arrangement interval of the magnetic sensors, but this increases the area of the semiconductor chip and causes an increase in cost. Moreover, when combining magnetic magnets magnetized separately, it takes time to assemble.

  An object of the present invention is to provide a rotation detection device having a simple structure and capable of accurately detecting an absolute angle with high resolution, and a bearing with a rotation detection device equipped with the rotation detection device.

The rotation detection device of the present invention includes a plurality of magnetic encoders concentrically provided on the surface of the same ring-shaped metal core and having different numbers of magnetic poles, and a plurality of magnetic encoders that respectively detect the magnetic fields of these magnetic encoders. A rotation detection device comprising a sensor and an angle calculation means for obtaining an absolute angle of the magnetic encoder based on a magnetic field signal detected by each of the magnetic sensors, the rotation detecting device being positioned between the adjacent magnetic encoders on the mandrel. Further, a ring-shaped bent shape portion that protrudes in the shape of a folded piece is formed concentrically with the metal core on the surface side where each of these magnetic encoders is provided.
According to the above configuration, since the number of magnetic poles of the plurality of magnetic encoders is different from each other, the absolute angle can be detected. For example, when a magnetic pole pair is rotated using a magnetic encoder having 12 magnetic poles and a magnetic encoder having 13 magnetic poles, a phase shift corresponding to one magnetic pole pair occurs in one rotation between the signals of two magnetic sensors that detect these magnetic fields. Therefore, the absolute angle in one rotation section can be calculated by the angle calculation means based on this phase difference.
In particular, the ring-shaped mandrel is formed between the adjacent magnetic encoders with a ring-shaped bent portion protruding in a folded piece shape, so that the adjacent magnetic encoders are separated by the bent-shaped portion of the core metal. Is done. This makes it possible to reduce the interference between the magnetic patterns of both magnetic encoders without increasing the distance between the corresponding magnetic sensors, and to reduce the absolute angle detection error caused by the magnetic field interference. Can be detected with high accuracy. Further, since the detection accuracy of the absolute angle can be increased without increasing the interval between the magnetic sensors, the manufacturing cost can be reduced even when the magnetic sensor is integrated on a semiconductor chip together with an arithmetic circuit or the like to constitute a sensor module. In addition, since a plurality of magnetic encoders are provided on one metal core, a simple structure can be achieved. As a result, the structure is simple, and the absolute angle can be accurately detected with high resolution.

In this invention, it is good also considering the front end height of the bending shape part of the said metal core more than the surface height of the said magnetic encoder.
If the tip height of the bent part of the core metal is equal to or higher than the surface height of the magnetic encoder, the interference of magnetic patterns generated between adjacent magnetic encoders separated by the bent part will be more effectively suppressed. Thus, the absolute angle detection accuracy can be further improved.

In this invention, the tip height of the bent shape portion of the metal core is made lower than the surface height of the magnetic encoder, and adjacent magnetic encoders sandwiching the bent shape portion are separated from each other at the tip of the bent shape portion. May be.
Also in this case, since the adjacent magnetic encoders are completely separated from each other at the tip position of the bent portion, a gap is generated, so that an effect of suppressing interference of magnetic patterns generated between these two magnetic encoders can be obtained. In addition, in this case, the distance between the cored bar and the magnetic sensor can be properly ensured.

In the present invention, the cored bar may be made of a magnetic material.
The material of the cored bar may be a non-magnetic material, but if the cored bar is made of a magnetic material, the interference of the magnetic pattern generated between adjacent magnetic encoders can be reduced, and the interval between the corresponding magnetic sensors is widened. The absolute angle can be accurately detected without any problem.

  In the present invention, each of the magnetic encoders is formed by vulcanizing and bonding an elastic member mixed with magnetic powder to a core made of magnetic material, and forming magnetic poles alternately in the circumferential direction on the rubber. A magnet may be used.

  In the present invention, each of the magnetic encoders is provided with a resin molded body obtained by molding a resin mixed with magnetic powder on a magnetic cored bar, and magnetic poles are alternately formed in the circumferential direction of the resin molded body. Thus, a resin magnet may be used.

  In the present invention, each magnetic encoder is a sintered magnet in which magnetic poles are alternately formed in the circumferential direction on a sintered body obtained by sintering a mixed powder of magnetic powder and non-magnetic powder. There may be.

In this invention, each said magnetic sensor may be comprised with the line sensor in which a sensor element is located in a line with the arrangement direction of the magnetic pole of a magnetic encoder.
If the magnetic sensor is such a line sensor, the magnetic field distribution of the magnetic encoder can be detected more finely as a sinusoidal signal based on an analog voltage rather than as an on / off signal, and a precise absolute angle diameter can be obtained.
In this case, the magnetic sensor composed of the line sensor may generate a sin and cos two-phase output signal by calculation to detect a position in the magnetic pole. Each of the magnetic sensors has a plurality of sensor elements arranged at positions shifted in the magnetic pole arrangement direction within the magnetic pole pitch, instead of being line sensors, and obtains two-phase output signals of sin and cos. It is also possible to detect by multiplying the position in the magnetic pole.

The bearing with a rotation detection device of the present invention is obtained by mounting the rotation detection device of any one of the above configurations of the present invention on a bearing.
According to this configuration, since the rotation detection device is integrated with the bearing, positioning of the magnetic encoder and the magnetic sensor is not necessary, which is easy to use. In addition, while having an absolute angle detection function, the number of parts and the number of assembling steps of the bearing-using device can be reduced and the size can be reduced.

The rotation detection device of the present invention includes a plurality of magnetic encoders concentrically provided on the surface of the same ring-shaped metal core and having different numbers of magnetic poles, and a plurality of magnetic encoders that respectively detect the magnetic fields of these magnetic encoders. In a rotation detection device comprising a sensor and angle calculation means for obtaining an absolute angle of a magnetic encoder based on a magnetic field signal detected by each of the magnetic sensors,
Since the ring-shaped bent portion that is located between the adjacent magnetic encoders and protrudes in a folded shape on the surface side where each of the magnetic encoders is provided is formed concentrically with the core metal, the structure is It is simple and can accurately detect the absolute angle with high resolution.
The bearing with a rotation detection device of the present invention is a device equipped with the rotation detection device having the above-described configuration according to the present invention. The number of assembly processes can be reduced and the size can be reduced.

  An embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows a schematic configuration of the rotation detection device of this embodiment. The rotation detection device 1 includes a plurality of (here, two) magnetic encoders 2A and 2B provided in a ring shape concentric with an axis O on the outer periphery of a rotating member 4 such as a rotating shaft of a motor, for example. A plurality of (here, two) magnetic sensors 3A and 3B that respectively detect the magnetic fields of the magnetic encoders 2A and 2B are provided.

  In the example of FIG. 1, the magnetic sensors 3A, 3B are fixed members 5 such as motor housings so as to face each of the magnetic encoders 2A, 2B in the radial direction (radial direction) through a minute gap. Is provided. Here, the magnetic sensor 3A faces the magnetic encoder 2A, and the magnetic sensor 3B faces the magnetic encoder 2B.

  FIG. 3 is a cross-sectional view taken along the line III-III in FIG. As shown in the figure, the magnetic encoders 2A and 2B are attached to the outer periphery of the rotating member 4 via the same cored bar 12. That is, the cored bar 12 is a ring-shaped member, and two magnetic encoders 2A and 2B are provided on the outer peripheral surface thereof side by side in the axial direction. A fitting cylinder portion 12b having a smaller diameter than the magnetic encoder installation portion 12a and extending in the axial direction is formed on one side portion of the magnetic encoder installation portion 12a of the core metal 12 via a step portion 12c. The cored bar 12 is fixed to the rotating member 4 by fitting the fitting cylinder portion 12 b to the outer peripheral surface of the rotating member 4. The magnetic encoder installation portion 12a of the cored bar 12 is located between the adjacent magnetic encoders 2A and 2B, and protrudes in a folded piece shape toward the outer peripheral surface where the magnetic encoders 2A and 2B are provided. A ring-shaped bent portion 12aa is formed concentrically with the cored bar 12. Adjacent magnetic encoders 2A and 2B are separated by the bent shape portion 12aa. The core metal 12 is made of a press-formed product of a metal plate such as a steel plate.

  The magnetic encoders 2A and 2B are ring-shaped magnetic members in which a plurality of magnetic pole pairs (one set of a magnetic pole S and a magnetic pole N) are magnetized at an equal pitch in the circumferential direction. In the example of FIG. A magnetic pole pair is magnetized on the outer peripheral surface. The number of magnetic pole pairs of these two magnetic encoders 2A and 2B is different from each other.

  As another example of the magnetic encoders 2A and 2B, as shown in FIG. 2, an axial type magnet in which a plurality of magnetic pole pairs are magnetized so as to be arranged at an equal pitch in the circumferential direction on the end surface in the axial direction of a ring-shaped magnetic member May be used. In this example, two magnetic encoders 2A and 2B are arranged so as to be adjacent to the inner and outer circumferences. In the case of the axial type magnetic encoders 2A and 2B, the magnetic sensors 3A and 3B are arranged in the axial direction facing the magnetized surface.

  FIG. 4 shows a sectional view taken along the line IV-IV in FIG. As shown in the figure, the axial type magnetic encoders 2 </ b> A and 2 </ b> B are also attached to the rotating member 4 through the same cored bar 12. The cored bar 12 in this case includes a ring-shaped flat magnetic encoder installation part 12a in which the magnetic encoders 2A and 2B are installed concentrically, and a fitting cylinder extending in the axial direction from the inner diameter side end of the magnetic encoder installation part 12a. Part 12d. The cored bar 12 is fixed to the rotating member 4 by fitting the fitting cylinder portion 12 d to the outer peripheral surface of the rotating member 4. Also in this case, the magnetic encoder installation portion 12a of the cored bar 12 is positioned between the adjacent magnetic encoders 2A and 2B and is folded back toward the surface on which the magnetic encoders 2A and 2B are provided. A ring-shaped bent portion 12aa protruding in the direction of the core metal 12 is formed concentrically. Adjacent magnetic encoders 2A and 2B are separated by the bent shape portion 12aa.

  The tip height of the bent shape portion 12aa in the cored bar 12 may be equal to or higher than the surface height of the magnetic encoders 2A and 2B as shown in FIG. 5A, or the magnetic encoders 2A and 2B as shown in FIG. The magnetic encoders 2A and 2B which are adjacent to each other with the bent shape portion 12aa interposed therebetween may be completely separated at the tip of the bent shape portion 12aa.

The magnetic encoders 2A and 2B are formed by, for example, vulcanizing and bonding an elastic member mixed with magnetic powder to a cored bar 12 made of a magnetic material, and forming magnetic poles alternately in the circumferential direction with rubber. Configured as a magnet.
As another configuration example of the magnetic encoders 2A and 2B, a resin molded body obtained by molding a resin mixed with magnetic powder is provided on a core 12 made of a magnetic body, and the resin molded bodies are alternately arranged in the circumferential direction. Magnetic poles may be formed on the resin magnets.
As still another configuration example of the magnetic encoders 2A and 2B, magnetic poles are alternately formed in a circumferential direction on a sintered body obtained by sintering a mixed powder of magnetic powder and non-magnetic powder, thereby forming a sintered magnet. Also good.

The magnetic sensors 3A and 3B have a function of detecting magnetic poles with a resolution higher than the number of magnetic pole pairs of the corresponding magnetic encoders 2A and 2B, that is, a function of detecting position information within the magnetic pole ranges of the magnetic encoders 2A and 2B. It is supposed to be. In order to satisfy this function, for example, as the magnetic sensor 3A, when the pitch λ of one magnetic pole pair of the corresponding magnetic encoder 2A is one cycle, the phase difference is 90 degrees (λ / 4) as shown in FIG. Two magnetic sensor elements 3A1 and 3A2 arranged apart from each other in the arrangement direction of the magnetic poles may be used. A Hall element or the like is used for each of the magnetic sensor elements 3A1 and 3A2. Calculation is performed by multiplying the phase in the magnetic pole (φ = tan ⁻¹ (sinφ / cos φ)) from the two-phase signals (sinφ, cosφ) obtained by these two magnetic sensor elements 3A1, 3A2. The same applies to the other magnetic sensors 3B. The waveform diagram of FIG. 6 shows the arrangement of the magnetic poles of the magnetic encoder 2A in terms of magnetic field strength.

  When the magnetic sensors 3A and 3B have such a configuration, the magnetic field distribution of the magnetic encoders 2A and 2B can be detected more finely as a sinusoidal signal based on an analog voltage rather than as an on / off signal, and accurate absolute angle detection can be performed. It becomes possible.

  As another example of the magnetic sensors 3A and 3B having a function of detecting position information in the magnetic poles of the magnetic encoders 2A and 2B, a line sensor as shown in FIG. 7B may be used. That is, for example, as the magnetic sensor 3A, line sensors 3AA and 3AB in which the magnetic sensor elements 3a are arranged along the arrangement direction of the magnetic poles of the corresponding magnetic encoder 2A are used. FIG. 7A shows a section of one magnetic pole in the magnetic encoder 2A converted into a magnetic field intensity and shown in a waveform diagram. In this case, the first line sensor 3AA of the magnetic sensor 3A is disposed in association with the 90-degree phase section of the 180-degree phase section in FIG. 7A, and the second line sensor 3AB is the remaining 90. It is arranged in correspondence with the phase interval of degrees. With such an arrangement, the signal S1 obtained by adding the detection signal of the first line sensor 3AA by the adder circuit 31 and the signal S2 obtained by adding the detection signal of the second line sensor 3AB by the adder circuit 32 are different addition circuits. By adding in 33, a sin signal corresponding to the magnetic field signal as shown in FIG. 7C is obtained. Further, the signal S1 and the signal S2 via the inverter 35 are added by another adding circuit 34 to obtain a cos signal corresponding to the magnetic field signal as shown in FIG. The position in the magnetic pole is detected from the two-phase output signal thus obtained.

When the magnetic sensors 3A and 3B are configured by line sensors in this way, the section of one magnetic pole pair of the magnetic encoders 2A and 2B can be accurately multiplied by a two-phase signal (sinφ, cosφ). In addition, since the calculation such as the phase in the magnetic pole (φ = tan ⁻¹ (sinφ / cosφ)) is not required, the detection process is simple and the speed can be increased. In addition, since a multiple signal can be obtained by calculating a large number of sensor outputs in the chip circuit, the influence of the distortion of the magnetic field pattern and noise is reduced, and the gap between the magnetic encoders 2A and 2B is set to other sensor configurations. The phase of the magnetic encoders 2A and 2B can be detected with higher accuracy.

  For example, in the configuration example of FIG. 1, the magnetic sensors 3 </ b> A and 3 </ b> B are connected to the angle calculation means 19. The angle calculation means 19 includes a phase difference detection means 6 that obtains a phase difference between magnetic field signals detected by the magnetic sensors 3A and 3B, and an angle calculation section 7 that is connected to the subsequent stage. The angle calculation unit 7 is a unit that calculates the absolute angle of the magnetic encoders 2A and 2B based on the phase difference detected by the phase difference detection unit 6.

  A schematic operation of absolute angle detection by the rotation detection device 1 having this configuration will be described below with reference to FIGS. In FIG. 1, if the number of magnetic pole pairs of the two magnetic encoders 2B and 2A is P and P + n, there is a phase difference of n magnetic pole pairs per rotation between the magnetic encoders 2A and 2B. The phases of the detection signals of the magnetic sensors 3A and 3B corresponding to the magnetic encoders 2A and 2B coincide with each other when rotated 360 / n degrees.

8A and 8B show examples of magnetic pole patterns of both magnetic encoders 2A and 2B, and FIGS. 8C and 8D show detection signals of magnetic sensors 3A and 3B corresponding to these magnetic encoders. The waveform is shown. In this case, the two magnetic pole pairs of the magnetic encoder 2B correspond to the three magnetic pole pairs of the magnetic encoder 2A, and the absolute position in this section can be detected. FIG. 8E shows a waveform diagram of the output signal of the phase difference obtained from the phase difference detecting means 6 of FIG. 1 based on the detection signals of FIGS. 8C and 8D.
FIG. 9 shows a waveform diagram of the detection phase and phase difference by the magnetic sensors 3A and 3B. 9A and 9B show examples of magnetic pole patterns of both magnetic encoders 2A and 2B, and FIGS. 9C and 9D show waveforms of detection phases of the corresponding magnetic sensors 3A and 3B. FIG. 9E shows a waveform diagram of the phase difference signal output from the phase difference detecting means 6.

  FIG. 10 shows a configuration example of an absolute angle detection circuit in the rotation detection device 1. Based on the detection signals of the magnetic sensors 3A and 3B as shown in FIGS. 8C and 8D, the corresponding phase detection circuits 13A and 13B are shown in FIGS. 9C and 9D, respectively. Output an accurate detection phase signal. The phase difference detection means 6 outputs a phase difference signal as shown in FIG. 9E based on these detected phase signals. The angle calculation unit 7 provided in the next stage performs a process of converting the phase difference obtained by the phase difference detection means 6 into an absolute angle according to a preset calculation parameter. Calculation parameters used in the angle calculation unit 7 are stored in a memory 8 such as a nonvolatile memory. In addition to the calculation parameters, the memory 8 stores information necessary for the operation of the apparatus, such as setting of the number of magnetic pole pairs of the magnetic encoders 2A and 2B, an absolute angle reference position, and a signal output method. Here, by providing the communication interface 9 at the next stage of the memory 8, the contents of the memory 8 can be updated through the communication interface 9. Thereby, the individual setting information can be variably set according to the use situation, and the usability is improved.

  The absolute angle information calculated by the angle calculation unit 7 is output from the angle information output circuit 10 or via the communication interface 9 as a modulation signal such as a parallel signal, serial data, analog voltage, or PWM. Further, the angle calculation unit 7 also outputs a rotation pulse signal. As the rotation pulse signal, any one of the detection signals of the two magnetic sensors 3A and 3B may be output. As described above, since each magnetic sensor 3A, 3B has a multiplication function, it can output a rotation signal with high resolution.

In the angle information output circuit 10 of FIG. 10, the absolute angle calculated by the angle calculation unit 7 is divided into two A-phase and B-phase pulse signals whose phases are 90 degrees different from each other, and a Z-phase pulse signal indicating the origin position. It may be output as an ABZ phase signal.
In this case, as shown in FIG. 11, when an absolute angle output request signal (request) is input from the receiving circuit 14 to the angle information output circuit 10, the absolute information in the angle information output circuit 10 is responded accordingly. The angle execution means 15 becomes operable, and the mode execution signal (ABS_mode = 1) indicating that the absolute angle output mode is in effect is generated from the mode execution signal generation means 16 in the angle information output circuit 10. The angle information output circuit 10 may be configured such that the A, B, and Z phase signals are output from the rotation pulse signal generation means 17. In the receiving side circuit 14, the position counter 18 indicating the absolute angle value is reset to 0 by receiving the Z-phase signal, and the A-phase signal and the B-phase signal output following the Z-phase signal are converted into the position counter 18. Counts. Once the pulse outputs of the A-phase signal and B-phase signal reach the current absolute angle value, the absolute angle output mode operation ends there (ABS_mode = 0). Thereafter, a rotation pulse signal (ABZ phase signal) corresponding to the change in the absolute angle detected with the rotation of the rotating member 4 (FIG. 1) is output from the angle calculation unit 7. As a result, the receiving-side circuit 14 that knows the absolute angle by counting the pulses is in a state in which the actual absolute angle information is always acquired after the absolute angle output mode operation ends (ABS_mode = 0). .

  In this way, when the rotation information such as the ABZ phase signal is output from the angle information output circuit 10 and the absolute angle information is output in the absolute angle output mode, there is no need to separately provide an interface for outputting the absolute angle. The circuit configuration of the rotation detection device 1 and the circuit configuration on the device side on which the rotation detection device 1 is mounted can be simplified.

In the rotation detection device 1, the magnetic sensors 3A and 3B and the signal processing circuit including the angle information output circuit 10 shown in FIG. 11 are integrated as a sensor module 11 as shown in the example of FIG. The sensor module 11 may be integrated on one semiconductor chip. When configured in this way, advantages such as a reduction in the number of parts, an improvement in the positional accuracy of the magnetic sensors 3A and 3B, a reduction in manufacturing costs, a reduction in assembly costs, and an improvement in detection accuracy due to signal noise reduction are obtained. Thus, a low-cost rotation detection device 1 can be obtained.
In this case, since one sensor module 11 is opposed to the two magnetic encoders 2A and 2B, the two magnetic encoders 2A and 2B are arranged close to each other.

As described above, the rotation detection device 1 includes a plurality of magnetic encoders 2A and 2B provided concentrically with the core metal 12 on the surface of the same ring-shaped metal core 12 and having different numbers of magnetic poles, and the magnetic encoders 2A and 2A. 2B includes a plurality of magnetic sensors 3A and 3B that respectively detect the magnetic field of 2B, and angle calculation means 19 that calculates the absolute angle of the magnetic encoders 2A and 2B based on the magnetic field signals detected by the magnetic sensors 3A and 3B. The absolute angles of the magnetic encoders 2A and 2B can be detected.
In particular, the ring-shaped cored bar 12 in which the magnetic encoders 2A and 2B are provided concentrically is folded between the adjacent magnetic encoders 2A and 2B on the surface side where the magnetic encoders 2A and 2B are provided. Since the ring-shaped bent shape portion 12aa protruding in a concentric manner is formed concentrically with the magnetic encoders 2A and 2B, the adjacent magnetic encoders 2A and 2B are separated by the bent shape portion 12aa of the core metal 12. Accordingly, interference between the magnetic patterns of both magnetic encoders 2A and 2B can be reduced without increasing the distance between the corresponding magnetic sensors 3A and 3B, and an absolute angle detection error caused by magnetic field interference. The absolute angle can be detected with high accuracy. In addition, since the detection accuracy of the absolute angle can be increased without increasing the distance between the magnetic sensors 3A and 3B, the sensor module 11 is configured by integrating the magnetic sensors 3A and 3B on the semiconductor chip together with an arithmetic circuit or the like. Manufacturing cost can be reduced. As a result, the structure becomes simple and the absolute angle can be detected with high resolution and high accuracy.

  The material of the core metal 12 may be a non-magnetic material or a magnetic material. Even if the metal core 12 is made of a non-magnetic material, the bent shape portion 12aa has the effect of separating the adjacent magnetic encoders 2A and 2B, thereby reducing the interference of magnetic patterns generated between the adjacent magnetic encoders 2A and 2B. Can do. If the mandrel 12 is made of a magnetic material, the interference of the magnetic pattern generated between the adjacent magnetic encoders 2A and 2B can be reduced, and the absolute angle can be accurately detected without increasing the interval between the corresponding magnetic sensors 3A and 3B. can do.

  When the tip height of the bent shape portion 12aa of the core metal 12 is equal to or higher than the surface height of the magnetic encoder 2A, 2B as shown in FIG. 5A, the adjacent magnetic encoder 2A, separated by the bent shape portion 12aa, The interference of the magnetic pattern generated during 2B can be more effectively suppressed, and the absolute angle detection accuracy can be further improved.

  The tip height of the bent portion 12aa of the core metal 12 may be lower than the surface height of the magnetic encoders 2A and 2B as shown in FIG. Also in this case, since the adjacent magnetic encoders 2A and 2B are completely separated from each other at the tip position of the bent shape portion 12aa, a gap is generated, so that interference of magnetic patterns generated between the two magnetic encoders 2A and 2B occurs. The effect which suppresses is acquired. In addition, in this case, the distance between the cored bar 12 and the magnetic sensors 3A and 3B can be properly secured.

  Further, by adjusting the thickness of the tip of the bent portion 12aa of the core metal 12, the interval between the adjacent magnetic encoders 2A and 2B can be set in accordance with the required absolute angle detection accuracy. For example, when the interval between the magnetic sensors 3A and 3B is set to 2 mm, the interval between the adjacent magnetic encoders 2A and 2B (the thickness at the tip of the bent shape portion 12aa) is preferably about 0.5 mm. However, even if the distance is only 0.1 mm, the effect of sufficiently reducing the interference of the magnetic pattern can be achieved.

  FIG. 12 shows the adjacent magnetic encoders 2A and 2B with the same configuration as the absolute angle error of the rotation detection device 1 of this embodiment in which the adjacent magnetic encoders 2A and 2B are separated by the bent shape portion 12aa of the core metal 12 described above. The result of having compared with the absolute angle error of the rotation detection apparatus at the time of adjoining without a clearance gap is shown with the graph. From this graph, even when the distance between the magnetic sensors 3A and 3B is the same, the rotation detecting device 1 of this embodiment provided with the bent shape portion 12aa is adjacent to the adjacent magnetic encoders 2A and 2B without a gap. It can be seen that the absolute angle error is reduced as compared with the rotation detection device.

  In this embodiment, an example using two magnetic encoders 2A and 2B is illustrated. However, the number of magnetic encoders is not limited to two, and a combination of three or more magnetic encoders having different numbers of magnetic pole pairs is wider. It may be configured to detect the absolute angle of the range. When this rotation detection device 1 is used to detect the rotation of the motor, if the combination of P and P + Pn is adjusted in accordance with the number of rotor poles Pn in the adjustment of the difference in the number of magnetic pole pairs, the rotation detection device 1 causes the motor to This is convenient for controlling the rotation of the motor.

  FIG. 13 is a cross-sectional view showing an embodiment of a bearing with a rotation detection device in which the rotation detection device 1 is mounted on a bearing. This bearing 20 with a rotation detection device is arranged at one end of a rolling bearing 21 in which a plurality of rolling elements 24 are interposed between an inner ring 22 that is a rotation-side raceway and an outer ring 23 that is a fixed-side raceway. Is provided. The rolling bearing 21 is a deep groove ball bearing, and rolling surfaces 22 a and 23 a of the rolling elements 24 are formed on the outer diameter surface of the inner ring 22 and the inner diameter surface of the outer ring 23, respectively. The bearing space between the inner ring 22 and the outer ring 23 is sealed with a seal 26 at the end opposite to the installation side of the rotation detection device 1.

  The two magnetic encoders 2 </ b> A and 2 </ b> B of the rotation detection device 1 are provided side by side in the axial direction on the outer diameter surface of the ring-shaped cored bar 12 that is press-fitted into the outer diameter surface of one end of the inner ring 22. The two magnetic encoders 2A and 2B are separated by the bent shape portion 12aa. As shown in FIG. 2, the two magnetic sensors 3A and 3B of the rotation detecting device 1 are integrated as a sensor module 11 together with other signal processing circuits, and are inserted inside a ring-shaped metal sensor housing 28. The resin mold 29 is attached to the inner diameter surface of one end of the outer ring 23 via the sensor housing 28. As a result, the magnetic encoders 2A and 2B and the corresponding magnetic sensors 3A and 3B are arranged to face each other in the radial direction. The lead wire 30 connected to the sensor module 11 passes through the sensor housing 28 and is drawn out to the outside, and exchange of signals and power supply are performed between the sensor module 11 and an external circuit via the lead wire 30.

  In this bearing 20 with a rotation detection device, since the rotation detection device 1 is mounted on the rolling bearing 21, positioning of the magnetic encoders 2A and 2B and the magnetic sensors 3A and 3B is not required, which is easy to use. In addition, while having an absolute angle detection function, it is possible to reduce the number of parts and the number of assembling steps of a bearing-using device, and to make it compact.

It is the schematic of the example of 1 structure of the rotation detection apparatus concerning one Embodiment of this invention. It is a principal part side view of the other structural example of the rotation detection apparatus. FIG. 3 is an enlarged sectional view taken along the line III-III in FIG. 1. It is an IV-IV arrow expanded sectional view in FIG. (A) is sectional drawing of an example of the bending shape part of a metal core, (B) is sectional drawing of the other example of the bending shape part of a metal core. It is explanatory drawing of the example of 1 structure of a magnetic sensor. It is explanatory drawing of the other structural example of a magnetic sensor. It is a wave form diagram of the detection signal of a magnetic sensor, and the detection signal of a phase difference detection means. It is a wave form diagram which shows the phase of the detection signal of each magnetic sensor, and the phase difference of both detection signals. It is a block diagram which shows one structural example of the absolute angle detection circuit of this rotation detection apparatus. It is a block diagram which shows the example of 1 structure of the angle information output circuit in this rotation detection apparatus. It is a graph which compares the absolute angle error of this rotation detection apparatus with the absolute angle error of another rotation detection apparatus. It is sectional drawing which shows one Embodiment of the bearing with a rotation detection apparatus which mounted this rotation detection apparatus in the bearing.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Rotation detection apparatus 2A, 2B ... Magnetic encoder 3A, 3B ... Magnetic sensor 3A1, 3A2 ... Magnetic sensor element 3AA, 3AB ... Line sensor 12 ... Core metal 12aa ... Bending shape part 19 ... Angle calculation means 20 ... With rotation detection apparatus Bearing 21 ... Rolling bearing

Claims (9)

A plurality of magnetic encoders that are concentrically provided on the surface of the same ring-shaped metal core and have different numbers of magnetic poles, a plurality of magnetic sensors that respectively detect the magnetic fields of these magnetic encoders, and a In a rotation detection device comprising angle calculation means for obtaining an absolute angle of a magnetic encoder based on a detected magnetic field signal,
The cored bar is formed concentrically with the cored bar so as to be positioned between adjacent magnetic encoders and to be bent in the shape of a folded piece on the surface side where the magnetic encoders are provided. A rotation detection device.   The rotation detection device according to claim 1, wherein the tip height of the bent portion of the core metal is equal to or higher than the surface height of the magnetic encoder.   2. The magnetic encoder according to claim 1, wherein the tip height of the bent shape portion of the metal core is lower than the surface height of the magnetic encoder, and the adjacent magnetic encoders sandwiching the bent shape portion are arranged at the tip of the bent shape portion. Rotation detectors separated from each other.   4. The rotation detection device according to claim 1, wherein the cored bar is made of a magnetic material.   5. The magnetic encoder according to claim 1, wherein each of the magnetic encoders is formed by vulcanizing and bonding an elastic member mixed with magnetic powder to a magnetic cored bar, and A rotation detection device in which magnetic poles are alternately formed in a direction to form a rubber magnet.   5. The magnetic encoder according to claim 1, wherein each magnetic encoder is provided with a resin molded body obtained by molding a resin mixed with magnetic powder on a magnetic core. A rotation detection device in which magnetic poles are alternately formed in the circumferential direction to form a resin magnet.   5. The magnetic encoder according to claim 1, wherein the magnetic encoder alternately forms magnetic poles in a circumferential direction on a sintered body obtained by sintering a mixed powder of magnetic powder and nonmagnetic powder. Rotation detector that is a sintered magnet.   8. The rotation detection device according to claim 1, wherein each of the magnetic sensors includes a line sensor in which sensor elements are arranged along an arrangement direction of magnetic poles of the magnetic encoder.   A bearing with a rotation detection device, wherein the rotation detection device according to any one of claims 1 to 8 is mounted on the bearing.

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