JP4673757B2 - Rotation angle detector - Google Patents

Description

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

  In recent years, various systems for improving running stability, such as a vehicle stability control system and an electronically controlled suspension system, are being mounted on the vehicle as the functions of the vehicle become higher. These systems acquire the steering angle of steering as one piece of vehicle posture information, and control the vehicle posture to be in a stable state based on the posture information. Therefore, for example, a rotation angle detecting device for detecting the steering angle of the steering is incorporated in the steering column of the vehicle. As this type of rotation angle detection device, there are an absolute angle detection method for detecting a steering angle with an absolute value and a relative angle detection method for detecting a steering angle with a relative value. Further, the absolute angle detection type rotation angle detection device is classified into an optical type and a magnetic type. Which of the relative angle detection method, the absolute angle detection method, and the optical method and the magnetic method in the absolute angle detection method is determined according to the product specifications and the like.

  As an optical rotation angle detection device, for example, a configuration as shown in Patent Document 1 is known. This rotation angle detecting device includes a rotating plate mounted in a penetrating manner on the steering shaft, and slit patterns having different patterns are provided on a plurality of circumferences of different radii on the rotating plate. Further, the same number of optical sensors (photo interrupters) as the slit rows are arranged on the rotating plate so as to correspond to the plurality of slit rows. Each optical sensor outputs a code of 3 bits in total based on the presence or absence of slits in the slit row. The slit row is provided so that the code does not overlap during one rotation of the rotating plate. For this reason, the rotation angle detection device can detect the rotation angle of the rotating plate during one rotation (within 360 °) as an absolute value based on the code.

  Further, the rotation angle detection device includes a gear body that rotates in the opposite direction to the rotation plate in conjunction with the rotation of the rotation plate (more precisely, the steering shaft). A magnet is fixed to the gear body, and a magnetic sensor is disposed so as to face the magnet. The magnetic sensor detects the intensity of the magnetic field emitted from the magnet, and the rotation angle detection device detects the number of rotations of the rotating plate based on the detection signal. Then, the rotation angle detection device is performing multiple rotations (for example, ± 3 rotations) of the rotating plate, that is, the steering shaft, based on the combination data of the codes output from the respective optical sensors and the detection signals output from the magnetic sensors. The rotation angle of is detected as an absolute value.

On the other hand, as a magnetic rotation angle detection device, for example, a configuration as shown in Patent Document 2 is known. This rotation angle detection device includes a main drive gear that rotates integrally with the steering shaft, and two driven gears that mesh with the gear. The number of teeth of the two driven gears is different, so that the rotation angles of both driven gears accompanying the rotation of the main driven gear are made different. A magnet is fixed to both driven gears, and a magnetic sensor is disposed to face the magnet. The magnetic sensor detects the intensity of the magnetic field emitted from the magnet and also detects a change in the direction of the magnetic flux of the magnet accompanying the rotation of both driven gears. Then, the rotation angle detection device detects the rotation angle of both driven gears based on the detection signals from both magnetic sensors, and determines the rotation angle of the steering shaft based on the detected rotation angle.
JP 2002-98522 A Japanese National Patent Publication No. 11-500828

  However, the rotation angle detection device of Patent Document 1 has the following problems. That is, in the rotation angle detecting device, it is necessary to provide a plurality of slit rows having different patterns on the rotating plate on a concentric circle, and thus it is necessary to secure the outer diameter of the rotating plate to some extent. For this reason, there has been a limit to the reduction in the diameter of the rotating plate and the downsizing of the rotation angle detector. Incidentally, in order to increase the resolution of the absolute angle of the rotating plate to be detected, the number of slit rows of the rotating plate may be increased. However, in this case, it is necessary to increase the outer diameter of the rotating plate by an amount corresponding to the increased number of slit rows, and accordingly, the physique of the rotation angle detecting device increases. Further, in the rotation angle detection device of Patent Document 1, since it is necessary to provide the same number of optical sensors as the slit rows, it is difficult to reduce the optical sensors, and one of the obstacles to the reduction in the number of parts. It was.

  On the other hand, in the magnetic rotation angle detection device of Patent Document 2, unlike the optical type, a rotating plate is not required, but two driven gears meshed with the main driving gear are required. And since it is necessary to ensure a certain size also about the housing which accommodates these main driving gears, both driven gears, etc., there was a limit in miniaturization of a rotation angle detecting device. Further, in the rotation angle detection device, two driven gears are essential, and there is a limit to reducing the number of parts.

  Recently, there is still a high demand for cost reduction for vehicles, and further cost reduction is required for various devices and parts mounted on such vehicles. From this point of view, there is a demand for simplification of the configuration and further reduction in product cost in the rotation angle detection device. Further, in the vicinity of the steering shaft, it is often difficult to ensure a sufficient space for the rotation angle detection device due to the arrangement relationship with other mechanisms arranged around the steering shaft. For this reason, there is still a demand for downsizing of the apparatus from the viewpoint of mounting the rotation angle detection apparatus on a vehicle.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a rotation angle detection device that can be simplified in configuration and thus reduced in size.

According to the first aspect of the present invention, in the rotation angle detecting device for detecting the rotation angle of the rotating body, the rotating body is provided so as to be integrally rotatable, and the N pole and the S pole are alternately provided in the rotating direction. A plurality of magnetic sensors for detecting a change in the direction of magnetic flux emitted from the magnet or a change in the strength of the magnetic flux accompanying the rotation of the magnet, and outputting a plurality of detection signals having different phases; Calculating means for obtaining a rotation angle of the rotating body based on a plurality of detection signals output from the magnetic sensor, wherein the plurality of magnetic sensors are disposed with their positions relative to the magnet being shifted from each other. the combination of the values of the detection signals from the magnetic sensor is different, the magnetization pattern of the magnets, is gradually increased or decreased in the direction of rotation of the wearing磁角said rotary member of each pole That it has to be set to so that the gist thereof.

  According to the present invention, since the positions of the plurality of magnetic sensors with respect to the magnets are shifted from each other, the phases of the output signals from the plurality of magnetic sensors are shifted from each other. For this reason, combinations of values of output signals from a plurality of magnetic sensors are different. Here, depending on the magnetization pattern of each magnetic pole of the magnet, there is a concern that the same combination appears in the combination of detection signal values from each magnetic sensor. On the other hand, in the present invention, since the magnetization pattern of the magnet is set so that all combinations of the values of the output signals from the plurality of magnetic sensors are different, the values of the detection signals from the plurality of magnetic sensors are set. In combination, the same combination does not appear. For this reason, the calculation means can obtain the rotation angle during one rotation of the rotating body as an absolute value based on the combination of the values of the detection signals from the plurality of magnetic sensors.

  Conventionally, two driven gears having different numbers of teeth are meshed with the main driving gear that rotates integrally with the rotating body, and the rotation angle of the rotating body is based on the rotation angles of the two driven gears accompanying the rotation of the main driving gear. There is known a rotation angle detection device that calculates the above. In this conventional rotation angle detection device, the two driven gears are one of the obstacles to simplifying the configuration and reducing the size. On the other hand, according to the present invention, the two driven gears are not necessary. For this reason, the number of parts can be reduced, and the configuration can be simplified. Further, since the two driven gears are not required, the rotation angle detection device can be reduced in size.

The magnetization pattern of the magnets, For example, it is contemplated that wear磁角of each magnetic pole is gradually increased or decreased in the direction of rotation of the rotating body. In this way, all combinations of output signals from the magnetic sensors can be easily varied.

Further, as shown in claim 2 , if the magnetization pattern of the magnet is set so that the magnetization angle of each magnetic pole is increased or decreased in an arithmetic progression in the rotation direction of the rotating body, Setting the magnetized pattern of the magnet becomes even easier.

Furthermore, the magnetization pattern of the magnet, as described in 請 Motomeko 3, wearing磁角adjacent magnetic poles may be all different. Even with such a magnetized pattern, the combination of output signals from the magnetic sensors can be varied.

Here, in the magnetization pattern of each magnetic pole of the magnet described in claim 3, depending on the setting of the magnetization angle of each magnetic pole, the same combination may appear in the combination of detection signals from each magnetic sensor. Concerned.

Therefore, as described in claim 4, by setting the magnet magnetization pattern in consideration of the detection resolution of the rotation angle of the arithmetic means, all combinations of detection signals from the respective magnetic sensors are made different. If it does so, the reliability with respect to the detection of the rotation angle (absolute angle) of a rotary body can be ensured. That is, in the combination of detection signals from each magnetic sensor, the magnetization angle of each magnetic pole of the magnet is such that the angle at which the same combination appears is not an integer multiple of the detection resolution (angle) of the rotation angle of the computing means. Set. In this way, in the actual combination of detection signals of the magnetic sensor, even if the same combination appears, the same combination does not appear as a combination of detection signals recognized by the calculation means. Note that by adjusting the detection resolution of the calculation means, all combinations of detection signals of the magnetic sensors recognized by the calculation means may be different.

  According to the present invention, it is possible to simplify the configuration of the rotation angle detection device and to reduce the size thereof.

<First Embodiment>
DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment in which the present invention is embodied in, for example, a rotation angle detection device that detects the steering angle of a steering wheel in a vehicle as an absolute value will be described with reference to FIGS.

<Overall configuration of rotation angle detection device>
As shown in FIG. 1, the rotation angle detection device 11 is mounted on a steering shaft 12 that is disposed in a steering column of a vehicle (not shown) and is connected to a steering (not shown) so as to be integrally rotatable. The rotation angle detection device 11 includes a housing 13 fixed to a structure (not shown) around the steering shaft 12. The housing 13 includes a covered cylindrical upper housing 14 with a lower opening and a bottomed cylindrical lower housing 15 with an upper opening, and the upper housing 14 and the lower housing 15 abut each other's opening. Are combined in this way. An insertion hole 14a through which the steering shaft 12 can be inserted is formed in the top wall of the upper housing 14, and an insertion hole 15a through which the steering shaft 12 can be inserted is formed in the bottom wall of the lower housing 15. Yes. When the upper housing 14 and the lower housing 15 are combined, the two insertion holes 14a and 15a coincide with each other, and the steering shaft 12 rotates through a bearing (not shown) in the both insertion holes 14a and 15a. It is inserted as possible.

  In the housing 13, an annular magnet (permanent magnet) 21 is fitted on the steering shaft 12 so as to be integrally rotatable. A substrate 22 is fixed to the inner bottom surface of the housing 13 (more precisely, the lower housing 15), and first and second magnetic sensors 23 and 24 are provided on the substrate 22. The first and second magnetic sensors 23 and 24 are arranged on the side of the magnet 21 and slightly below.

<First and second magnetic sensors>
The first and second magnetic sensors 23 and 24 are each formed by integrating a magnetoresistive element circuit (not shown) and its signal processing circuit as a single IC chip. The magnetoresistive element circuit is a circuit in which four anisotropic magnetoresistive elements (so-called AMR elements) are connected in a bridge shape. This anisotropic magnetoresistive element is made of a ferromagnetic material such as Ni—Co having an anisotropic magnetoresistive effect, and its resistance value changes according to the applied magnetic field (more precisely, the direction of the magnetic flux). The first and second magnetic sensors 23 and 24 output the midpoint potential of the bridge-like circuit as a magnetic flux detection signal in accordance with the change in the magnetic field applied to them. In the magnetoresistive element circuit, the directions of the four anisotropic magnetoresistive elements are set so that the phase of the signal waveform of the detection signal output from the circuit is shifted by 90 °. Accordingly, the first and second magnetic sensors 23 and 24 each output two signals: a detection signal that conforms to a sine function (sine signal) and a detection signal that conforms to a cosine function (cosine signal).

  Since the direction of the magnetic flux passing through the first and second magnetic sensors 23 and 24 varies depending on the rotational position of the magnet 21, that is, the operation position (steering angle) of the steering shaft 12, the midpoint potential is also determined by the steering shaft. It changes according to 12 operation positions. For this reason, the first and second magnetic sensors 23 and 24 receive the magnetic flux generated from the magnet 21 in the direction corresponding to the operation position of the steering shaft 12, and at a potential corresponding to the operation position of the steering shaft 12. A detection signal is output.

<Magnet>
The magnet 21 is formed by magnetizing the surface of an annular base material formed of a ferromagnetic material such as neodymium or samarium so as to have a predetermined magnetization pattern using a magnetizing device (not shown). Has been. In the present embodiment, for example, as shown in FIG. 2A, in the circumferential direction of the annular magnet 21, a 10-pole sector shape is formed so that different polarities, that is, N and S poles are alternately arranged. The magnetic poles P1, P2, P3, P4, P5, P6, P7, P8, P9, and P10 are magnetized. As shown in the list of FIG. 2B, the correspondence between each of the magnetic poles P1 to P10 and the polarity (N pole and S pole) is N pole, and P2 is P2, P9, and P9. , P4, P6, P8, and P10 are S poles.

  The 10 poles P1 to P10 have a magnetization angle (center angle) that is an angle formed by connecting both ends of their outer peripheral surfaces (arcs) and the center of the magnet 21 (that is, the rotation center of the steering shaft 12) O. .theta.1, .theta.2, .theta.3, .theta.4, .theta.5, .theta.6, .theta.7, .theta.8, .theta.9, .theta.10 are provided so as to gradually increase clockwise from the reference position S shown in FIG. In addition, the magnetization angles θ1 to θ10 of the magnetic poles P1 to P10 are set so that the sum thereof is 360 °.

  In the present embodiment, the magnetization angles θ1 to θ10 of the magnetic poles P1 to P10 are set so as to increase clockwise from the reference position S in an arithmetic progression. Specifically, the magnetization angles θ1 to θ10 are an equidistant sequence with the magnetization angle θ1 as the first term (reference) and a tolerance of 4 °, for example. 2B, in this embodiment, for example, θ1 = 18 °, θ2 = 22 °, θ3 = 26 °, θ4 = 30 °, θ5 = 34 °, θ6 = 38 °. , Θ7 = 42 °, θ8 = 46 °, θ9 = 50 °, and θ10 = 54 °. The magnet 21 is strong enough to position the first and second magnetic sensors 23 and 24 in the magnetic field (magnetic flux) emitted from the magnet 21.

<First and second magnetic sensors and arrangement of magnets>
As shown in FIG. 2A, the first and second magnetic sensors 23 and 24 are arranged at different positions with respect to the magnet 21. That is, the first and second magnetic sensors 23 are such that the extension line of the radius of the magnet 21 intersects the midpoint M of the line segment connecting the centers C1 and C2 of the first and second magnetic sensors 23 and 24. , 24 are arranged. In the present embodiment, an angle θs that can connect the centers C1, C2 of the first and second magnetic sensors 23, 24 and the center O of the magnet 21 is 50 °, for example. Accordingly, with the rotation of the magnet 21, a magnetic field whose phase is shifted by 50 ° is applied to the first and second magnetic sensors 23 and 24. As a result, the phases of the detection signals (sine signal and cosine signal) output from the first and second magnetic sensors 23 and 24 are also shifted by 50 °.

<Electrical configuration>
Next, the electrical configuration of the rotation angle detection device will be described.
As shown in FIG. 3, the rotation angle detection device 11 includes a power circuit 31 and a microcomputer 32 in addition to the first and second magnetic sensors 23 and 24. The power supply circuit 31 converts a voltage input from a vehicle battery (not shown) into a voltage of a predetermined level corresponding to each part of the rotation angle detector 11 such as the first and second magnetic sensors 23 and 24 and the microcomputer 32. Then, these voltages are supplied to each part of the rotation angle detector 11. The first and second magnetic sensors 23 and 24, the microcomputer 32, and the like operate using a predetermined level of voltage supplied from the power supply circuit 31 as an operation power supply.

  The first and second magnetic sensors 23 and 24 detect a change in the direction of the magnetic flux accompanying the rotation of the magnet 21, and are analog signals that continuously change according to the rotation angle φ of the magnet 21, that is, a sine function. A sine signal according to the above and a cosine signal according to the cosine function are respectively output. The analog signals from the first and second magnetic sensors 23 and 24 are subjected to processing such as amplification by the signal processing circuit, and the processed analog signals are sent to the microcomputer 32.

<Microcomputer>
The microcomputer 32 includes a CPU (central processing unit) (not shown), an A / D converter that converts analog signals into digital signals, ROM (read only memory), RAM (write / read memory), and digital signals. It consists of a D / A converter that converts it into an analog signal. In the ROM, various control programs and data for overall control of the entire rotation angle detection device 11 are stored in advance. The control program includes a rotation angle calculation program. This program is based on analog signals (sine signal and cosine signal) from the first and second magnetic sensors 23 and 24 digitally converted by the A / D converter. 21 is a program for calculating (the rotation angle of 21). The RAM is a data storage area, that is, a work area for the CPU to execute various processes by developing the ROM control program. Then, the CPU obtains the rotation angle φ of the steering shaft 12 according to the rotation angle calculation program stored in the ROM.

<Rotation angle calculation method>
Next, a method for calculating the rotation angle of the steering shaft by the rotation angle detection device configured as described above will be described.

  When the steering shaft 12 is rotated by a steering operation by the driver, the magnet 21 fixed to the steering shaft 12 is also integrally rotated. When the magnet 21 rotates, the change in the direction of the magnetic flux emitted from the magnet 21 is detected by the first and second magnetic sensors 23 and 24. The first and second magnetic sensors 23 and 24 output analog signals (sine signal and cosine signal) that change continuously according to the rotation angle φ of the magnet 21 to the microcomputer 32. Since the first and second magnetic sensors 23 and 24 are arranged at different positions with respect to the magnet 21, the phases of the analog signals output from the first and second magnetic sensors 23 and 24 are mutually different. Sneak away. In the present embodiment, the phases of the analog signals from the first and second magnetic sensors 23 and 24 are shifted by 50 °.

  Here, of the analog signals output from the first and second magnetic sensors 23 and 24, the sine signal is expressed by the following equation (A), and the cosine signal is expressed by the following equation (A). In both equations (a) and (b), Y1 is a sine value, Y2 is a cosine value, A1 is the amplitude (voltage value) of the sine signal, and A2 is the amplitude (voltage value) of the cosine signal. In both formulas (a) and (b), φ is the rotation angle of the magnet 21.

Y1 = A1sinφ (A)
Y2 = A2cosφ ... (A)
The microcomputer 32 first converts the analog signals (sine signal and cosine signal) output from the first and second magnetic sensors 23 and 24, respectively, into a digital signal by the A / D converter.

  Next, the microcomputer 32 calculates the tangent value according to the tangent function based on the analog signals (sine signal and cosine signal) from the first and second magnetic sensors 23 and 24 that have been digitally converted into the following equation (c). And the arc tangent values Vh1 and Vh2 of the calculated two tangent values are obtained based on the following equation (D). Since the arc tangent values Vh1 and Vh2 correspond to the rotation angle φ of the magnet 21, the microcomputer 32 calculates the rotation angle φ by obtaining the arc tangent values Vh1 and Vh2.

Tangent value = Y1 / Y2 = tan φ (e)
Vh1, Vh2 = arctan (Y1 / Y2) = arctan (tan φ) = φ (D)
Here, the relationship between the rotation angle φ of the magnet 21, that is, the rotation angle φ of the steering shaft 12, and the inverse tangent values Vh1 and Vh2 of the first and second magnetic sensors 23 and 24 will be described. That is, as shown in FIG. 4, the rotation angle φ (electrical angle) of the magnet 21 is set on the horizontal axis, and the arctangent values Vh1, Vh2 (voltage values) of the first and second magnetic sensors 23, 24 are set on the vertical axis. When plotted on the axis, the two arc tangent values Vh1 and Vh2 are the first and second arc tangent signals Sc1 and Sc2 whose output values (voltage values) linearly change according to the rotation angle φ of the magnet 21. As required. The first and second arctangent signals Sc1 and Sc2 repeat rising and falling corresponding to the magnetization angles θ1 to θ10 of the magnetic poles P1 to P10.

  Further, since the amplitudes (voltage values) of the first and second arc tangent signals Sc1 and Sc2 are constant (5 V), the slopes of the first and second arc tangent signals Sc1 and Sc2 are the respective magnetic poles P1 to P1. It is determined by the magnetization angles θ1 to θ10 of P10. That is, as the magnetization angle increases, the slopes of the first and second arc tangent signals Sc1, Sc2 become smaller, and as the magnetization angle becomes smaller, the inclinations of the first and second arc tangent signals Sc1, Sc2 become larger. In the present embodiment, since the magnetization angles θ1 to θ10 of the ten magnetic poles P1 to P10 are all different, the first and second arctangent signals are generated while the magnet 21 rotates once (360 °). The rising slopes of Sc1 and Sc2 are all different.

  In the present embodiment, the phases of the analog signals output from the first and second magnetic sensors 23, 24 are shifted by 50 °, so that the first and second arctangent signals Sc1, Sc2 The phase difference is also 50 °. For this reason, the two detection signals output from the first and second magnetic sensors 23 and 24 do not overlap during one rotation of the magnet 21. That is, the two arctangent values Vh1 and Vh2 obtained based on the detection signals output from the first and second magnetic sensors 23 and 24 do not coincide with each other, and the combination of the two arctangent values Vh1 and Vh2 is not the case. Are all different. Therefore, the combination of the two arc tangent values Vh1 and Vh2 becomes a specific value with respect to the rotation angle φ of the magnet 21 while the magnet 21 makes one rotation. Therefore, if the arc tangent values Vh1 and Vh2 are known based on the detection signals from the first and second magnetic sensors 23 and 24, the rotation angle φ of the magnet 21 in the range of 360 °, that is, the rotation angle φ of the steering shaft 12 is obtained. (Absolute angle) can be detected immediately.

  When the microcomputer 32 calculates the rotation angle φ of the magnet 21, that is, the steering shaft 12, based on the two arc tangent values Vh1 and Vh2, a digital signal corresponding to the rotation angle φ is output by a D / A converter (not shown). Convert to analog. The microcomputer 32 converts the analog signal (continuous time signal) into various systems (more precisely, their control devices) for improving running stability such as a vehicle stability control system and an electronically controlled suspension system. Send to.

  If a rotational speed sensor (for example, a magnetic sensor such as an MRE sensor or a Hall sensor) for detecting the rotational speed of the magnet 21 is separately provided, the detection signal from the rotational speed sensor and the first and second magnetic fields are detected. Based on the detection signals from the sensors 23 and 24, it is also possible to detect multiple rotations of the magnet 21 (rotations of 360 ° or more).

<Effect of Embodiment>
Therefore, according to the present embodiment, the following effects can be obtained.
(1) Since the positions of the first and second magnetic sensors 23 and 24 with respect to the magnet 21 are shifted from each other, the phases of the output signals from the first and second magnetic sensors 23 and 24 are Deviation from each other. For this reason, combinations of output signals from the first and second magnetic sensors 23 and 24 are different. However, depending on the magnetization pattern of each of the magnetic poles P1 to P10 of the magnet 21, there is a concern that the same combination appears in the combination of detection signals (voltage values) from the first and second magnetic sensors 23 and 24. . On the other hand, in this embodiment, the magnetization pattern of the magnet 21 is set so that all combinations of output signals (voltage values) from the first and second magnetic sensors 23 and 24 are different. For this reason, in the combination of the detection signals from the first and second magnetic sensors 23 and 24, the same combination does not appear. Therefore, the microcomputer 32 can obtain the rotation angle φ during one rotation of the magnet 21, that is, the steering shaft 12 as an absolute value based on the combination of detection signals from the first and second magnetic sensors 23 and 24. It becomes possible.

  (2) Conventionally, a main driving gear that rotates integrally with the steering shaft and two driven gears with different numbers of teeth meshing with the gear are provided, and based on the rotation angle of both driven gears accompanying the rotation of the main driving gear. Thus, a rotation angle detection device that obtains the rotation angle φ of the steering shaft 12 is known. According to the present embodiment, unlike the conventional rotation angle detection device, the two driven gears are not required. For this reason, the number of parts can be reduced and the configuration can be simplified. Further, since the two driven gears are not required, the rotation angle detection device can be reduced in size.

  (3) As the magnetization pattern of the magnet 21, the magnetization angles θ <b> 1 to θ <b> 10 of the magnetic poles P <b> 1 to P <b> 10 are gradually increased in the rotation direction of the magnet 21. Specifically, the magnetization pattern of the magnet 21 is set so that the magnetization angles θ1 to θ10 of the magnetic poles P1 to P10 increase in an arithmetic progression in the rotation direction of the magnet 21. In this way, the rising slopes of the first and second arctangent signals Sc1 and Sc2 gradually decrease during one rotation of the magnet 21 (from 0 ° to 360 °) (see FIG. 4). ). That is, the rising slopes of the first and second arc tangent signals Sc1 and Sc2 are all different during one rotation of the magnet 21. Therefore, all combinations of output signals from the first and second magnetic sensors 23 and 24 can be easily changed.

<Second Embodiment>
Next, a second embodiment of the present invention will be described. This embodiment is different from the first embodiment in terms of the magnetized pattern of the magnet.

  As shown in FIG. 5A, the annular magnet 41 has four polar fan-shaped magnetic poles P1, P2, and so on in the circumferential direction so that different polarities, that is, N and S poles are alternately arranged. P3 and P4 are magnetized. As shown in the list of FIG. 5B, the correspondence between each of the magnetic poles P1 to P4 and the polarity (N pole and S pole) is that the magnetic poles P1 and P3 are N poles and the magnetic poles P2 and P4 are S poles. Has been. The magnet 41 is provided so that the magnetization angles of the magnetic poles having the same polarity among the plurality of magnetic poles P1 to P4 are all different. That is, each of the magnetic poles P1 to P1 of the magnet 41 so that the magnetization angle θ1 of the magnetic pole P1 and the magnetization angle θ3 of the magnetic pole P3 are different, and the magnetization angle θ2 of the magnetic pole P2 and the magnetization angle θ4 of the magnetic pole P4 are different. P4 is magnetized. Further, the magnetization angles θ1 to θ4 of the magnetic poles P1 to P4 of the magnet 41 are set so that the total of the magnetization angles θ1 to θ4 is 360 °. However, when the magnetization pattern of the magnet 41 is set in this way, depending on the setting of the magnetization angles θ1 to θ4 of the magnetic poles P1 to P4, the first and second magnetic sensors 23 and 24 It is feared that the same combination is expressed in the combination of detection signals.

  Specifically, as shown in the list of FIG. 5B, in this embodiment, θ1 = 85 °, θ2 = 85 °, θ3 = 95 °, and θ4 = 95 °. In this case, as shown in FIG. 6, the same combination appears twice for the three combinations of arctangent values Vh1 and Vh2 between 0 ° and 360 ° in electrical angle. The first is a combination of arctangent values Vh1 and Vh2 at an angle φ1 (40 ° <φ1 <60 °) and an arctangent value Vh1 and Vh2 at an angle φ6 (320 ° <φ6 <340 °). The second is a combination of arctangent values Vh1 and Vh2 at an angle φ2 (80 ° <φ2 <100 °) and an arctangent value Vh1 and Vh2 at an angle φ5 (260 ° <φ5 <280 °). The third is a combination of arctangent values Vh1 and Vh2 at an angle φ3 (120 ° φ3 <140 °) and arctangent values Vh1 and Vh2 at an angle φ4 (φ4 = 220 °).

  In this case, even if it is attempted to detect the rotation angle φ of the magnet 41, that is, the steering shaft 12 in the range of 0 ° to 360 °, in the combination of the arc tangent values Vh1 and Vh2 of the first and second arc tangent signals Sc1 and Sc2. The same combination is expressed twice. For this reason, the rotation angle φ of the magnet 41 may not be uniquely determined in the combination of the first and second arctangent signals Sc1 and Sc2. Therefore, there is a concern about the reliability of the detection of the rotation angle φ (absolute angle) of the magnet 41, that is, the steering shaft 12.

  Therefore, in this embodiment, by setting the magnetization pattern of the magnet 41 in consideration of the detection resolution of the rotation angle φ of the microcomputer 32 (more precisely, the A / D converter or the D / A converter). The combinations of the detection signals from the first and second magnetic sensors 23 and 24, and the combinations of the first and second arctangent signals Sc1 and Sc2, are all made different. That is, in the combination of detection signals from the first and second magnetic sensors 23, 24, at least one of the two angles constituting each set among the three sets of angles at which the same combination appears is a microcomputer. The magnetization angles θ1 to θ4 of the magnetic poles P1 to P4 of the magnet 41 are set so as to deviate from an integer multiple of the detection resolution (angle) of the rotation angle φ of 32. Specifically, among the angles φ1, φ6, φ2, φ5, and φ3, φ4, at least the angles φ1, φ2, φ3 or the angles φ6, φ5, φ4 are the detection resolution (angle) of the rotation angle φ of the microcomputer 32. ) Deviate from an integer multiple of). Note that the detection resolution of the rotation angle φ of the microcomputer 32 may be set so as to avoid at least one of the angles φ1, φ2, φ3 and the angles φ6, φ5, and φ4.

  In the present embodiment, as shown in FIG. 6, the detection resolution of the rotation angle φ of the magnet 41 of the microcomputer 32 is, for example, 20 °. Here, in the combination of the arc tangent values of the first and second arc tangent signals Sc1 and Sc2, the angle φ4 (= 220 °) at the angles φ1, φ6, the angles φ2, φ5, and the angles φ3, φ4 at which the same combination appears. The angle other than () is not an integer multiple of 20 °, which is the detection resolution of the rotation angle φ of the magnet 41 of the microcomputer 32. Therefore, in the actual combination of the detection signals of the first and second magnetic sensors 23 and 24, that is, the first and second arctangent signals Sc1 and Sc2, even if the same combination appears, the microcomputer 32 As a combination of detection signals recognized by, the same combination does not appear. For this reason, the reliability with respect to the detection of rotation angle (phi) (absolute angle) of the magnet 41, ie, the steering shaft 12, is securable.

Therefore, according to the present embodiment, the following effects can be obtained.
(1) The magnet 41 is provided so that the magnetization angles of the magnetic poles having the same polarity among the magnetic poles P1 to P4 are all different. That is, the magnetization angle θ1 of the magnetic pole P1 and the magnetization angle θ3 of the magnetic pole P3 are made different, and the magnetization angle θ2 of the magnetic pole P2 and the magnetization angle θ4 of the magnetic pole P4 are made different. The combination of output signals from the first and second magnetic sensors 23 and 24 can also be varied by such a magnetized pattern.

  (2) The detection signal from the first and second magnetic sensors 23 and 24 is set by setting the magnetization pattern of the magnet 41 in consideration of the detection resolution of the microcomputer 32 with respect to the rotation angle φ of the magnet 41. All combinations of were made different. Specifically, in the combination of detection signals from the first and second magnetic sensors 23 and 24, the angle at which the same combination appears is an angle that is an integral multiple of the detection resolution (angle) with respect to the rotation angle φ of the microcomputer 32. The magnetization angles θ1 to θ4 of the magnetic poles P1 to P4 of the magnet 41 are set so as to deviate from the above. For this reason, in the actual combination of the detection signals of the first and second magnetic sensors 23 and 24, even if the same combination is expressed, the same combination is expressed as the combination of the detection signals recognized by the microcomputer 32. Never do. Therefore, it is possible to ensure the reliability for detecting the rotation angle φ (absolute angle) of the magnet 41.

<Third Embodiment>
Next, a third embodiment of the present invention will be described. This embodiment is different from the second embodiment in the point of the magnetized pattern.

  As shown in FIG. 7 (a), the annular magnet 51 has four polar fan-shaped magnetic poles P1, P2, and so on in the circumferential direction so that different polarities, that is, N and S poles are alternately arranged. P3 and P4 are magnetized. As shown in the list of FIG. 7B, the correspondence between each of the magnetic poles P1 to P4 and the polarity (N pole and S pole) is as follows: the magnetic poles P1 and P3 are S poles; Has been. The magnets 51 are provided so that the magnetization angles of adjacent magnetic poles are all different. That is, the magnetization angle θ2 of the magnetic pole P2 is different from the magnetization angles θ2 and θ4 of the adjacent magnetic poles P2 and P4 so that the magnetization angle θ2 of the magnetic pole P1 is different from that of the adjacent magnetic poles P1 and P3. It is set differently from θ1 and θ3. The magnetization angle θ4 of the magnetic pole P4 is different from the magnetization angles θ2 and θ4 of the adjacent magnetic poles P2 and P4 so that the magnetization angle θ4 of the magnetic pole P3 is different from the magnetization angles θ2 and θ4 of the adjacent magnetic poles P2 and P4. It is set differently from θ1 and θ3. Specifically, as shown in the list of FIG. 7B, θ1 = 90 °, θ2 = 80 °, θ3 = 110 °, and θ4 = 80 °.

  In this case, as shown in FIG. 8, the same combination appears twice for the two combinations of arctangent values Vh1 and Vh2 between 0 ° and 360 ° in electrical angle. First, as shown in FIG. 8, a combination of arctangent values Vh1 and Vh2 at an electrical angle of 40 ° (= φ1) and an arctangent value Vh1 at an angle φ4 (300 ° <φ4 <320 °). This is a combination of Vh2. The second is a combination of arctangent values Vh1 and Vh2 at an angle φ2 (120 ° <φ2 <140 °) and an arctangent value Vh1 and Vh2 at an angle φ3 (220 ° <φ3 <240 °).

  Therefore, also in the present embodiment, the magnetization pattern of the magnet 51 is set in consideration of the detection resolution of the rotation angle φ of the microcomputer 32 (more precisely, the A / D converter or the D / A converter). I have to. That is, as shown in FIG. 8, the detection resolution of the rotation angle φ of the magnet 51 of the microcomputer 32 is set to 20 °, for example. Here, in the combination of the arc tangent values of the first and second arc tangent signals Sc1 and Sc2, the angle φ1, φ4, and the angles φ2 and φ3 at which the same combination appears other than the angle φ1 (φ = 40 °). The angle deviates from an integer multiple of 20 °, which is the detection resolution of the rotation angle φ of the magnet 41 of the microcomputer 32. Therefore, in the actual combination of the detection signals of the first and second magnetic sensors 23 and 24, that is, the first and second arctangent signals Sc1 and Sc2, even if the same combination appears, the microcomputer 32 As a combination of detection signals recognized by, the same combination does not appear.

  Therefore, even when the magnetized pattern of the magnet 51 is set as in the present embodiment, it is possible to ensure the reliability of detecting the rotation angle φ (absolute angle) of the magnet 51, that is, the steering shaft 12.

<Fourth embodiment>
Next, a fourth embodiment of the present invention will be described. This embodiment is different from the third embodiment in the point of the magnet magnetization pattern.

  As shown in FIG. 9A, the annular magnet 61 has two polar fan-shaped magnetic poles P1 and P2 in the circumferential direction so that different polarities, that is, N and S poles are alternately arranged. Magnetized. As shown in the list of FIG. 9B, the correspondence relationship between the magnetic poles P1 and P2 and the polarity (N pole and S pole) is such that the magnetic pole P1 is the N pole and the magnetic pole P2 is the S pole. The magnet 61 is provided so that the magnetization angles θ1 and θ2 of the adjacent magnetic poles P1 and P2 are different. Specifically, as shown in the list of FIG. 9B, θ1 = 190 ° and θ2 = 170 °.

  In this case, as shown in FIG. 10, the same combination appears once for two combinations of arctangent values Vh1 and Vh2 between 0 ° and 360 ° in electrical angle. That is, as shown in FIG. 10, the combination of arctangent values Vh1 and Vh2 at an angle φ1 (φ1 = 100 °) and the combination of arctangent values Vh1 and Vh2 at an angle φ2 (φ2 = 280 °) coincide.

  Therefore, also in the present embodiment, the magnetization pattern of the magnet 51 is set in consideration of the detection resolution of the rotation angle φ of the microcomputer 32 (more precisely, the A / D converter or the D / A converter). I have to. That is, as shown in FIG. 10, the detection resolution of the rotation angle φ of the magnet 61 of the microcomputer 32 is, for example, 15 °. In this case, in the combination of arc tangent values of the first and second arc tangent signals Sc1 and Sc2, the angle φ1 (= 100 °) and the angle φ2 (= 280 °) at which the same combination appears are the magnets of the microcomputer 32. This is a value that is an integral multiple of 15 °, which is the detection resolution of the rotation angle φ of 41. Therefore, in the actual combination of the detection signals of the first and second magnetic sensors 23 and 24, that is, the first and second arctangent signals Sc1 and Sc2, even if the same combination appears, the microcomputer 32 As a combination of detection signals recognized by, the same combination does not appear.

Therefore, the reliability for detecting the rotation angle φ (absolute angle) of the magnet 61, that is, the steering shaft 12, can be ensured also by the magnetized pattern as in the present embodiment.
<Other embodiments>
Each of the above embodiments may be modified as follows.

  In the first embodiment, the ten magnetic poles P1 to P10 are provided so that their magnetization angles θ1 to θ10 gradually increase clockwise from the reference position S shown in FIG. The magnetization angles θ1 to θ10 may be provided so as to gradually decrease clockwise from the reference position S shown in FIG.

  In the first embodiment, the magnetization angles θ1 to θ10 of the 10 magnetic poles P1 to P10 are set in an arithmetic progression of the initial term θ1 = 18 ° and a tolerance of 4 °. It may not be constant. That is, it is only necessary that the magnetization angles θ1 to θ10 of the magnetic poles P1 to P10 gradually increase or decrease clockwise from the reference position S shown in FIG. For example, the magnetization angles θ1 to θ10 of the magnetic poles P1 to P10 may be set in a geometric sequence. Even in this case, since all the magnetization angles θ1 to θ10 of the magnetic poles P1 to P10 are different, the rotation angle φ (absolute angle) of the magnet 21 and consequently the steering shaft 12 can be easily detected.

In the first embodiment, the 10-pole magnet 21 having the magnetic poles P1 to P10 is adopted, but the number of the magnetic poles of the magnet 21 may be arbitrarily changed as long as it is 2 poles or more.
In the first to fourth embodiments, a magnetic sensor (MRE sensor) using a magnetoresistive element is employed as the first and second magnetic sensors 23 and 24. For example, a Hall element (Hall IC) is used. A Hall sensor or a magnetic sensor (GMR sensor) using a giant magnetoresistive element may be employed. Further, an MRE sensor and a Hall sensor or GMR sensor may be mixed. For example, one of the first and second magnetic sensors 23 and 24 is an MRE sensor, and the other is a Hall sensor or a GMR sensor. Note that. The Hall sensor is preferably arranged so that the magnetic flux is perpendicular to the magnetic sensitive surface.

  In the first to fourth embodiments, the first and second magnetic sensors 23 and 24 are used. However, three, four, or more magnetic sensors may be provided. Even in this case, the magnetic sensors are arranged at different positions with respect to the magnets 21, 41, 51, 61. That is, the magnetic sensors may be arranged so as to be displaced from each other. In this way, even if only the first and second magnetic sensors 23 and 24 have the same combination in the combination of the arc tangent values of the first and second arc tangent signals Sc1 and Sc2. The expression of the same combination can be avoided. In addition, the magnetization pattern of the magnets 21, 41, 51, 61 can be simplified.

  In the first to fourth embodiments, a so-called full-bridge type MRE sensor including a single magnetoresistive element circuit in which four magnetoresistive elements are connected in a bridge shape, etc. Although the first and second magnetic sensors 23 and 24 are used, the following magnetic sensors may be used. That is, a so-called two-bridge full-bridge type MRE sensor including two sets of magnetoresistive elements and the like is used. In this case, two sets of magnetoresistive element circuits are provided at an angle of 45 ° on the substrate 22. In this way, two sets of analog signals (two sine signals and two cosine signals) consisting of a sine signal and a cosine signal are output from a single magnetic sensor. Since only a single magnetic sensor needs to be provided in the vicinity of the magnets 21, 41, 51, 61, the number of parts of the rotation angle detection device 11 can be further reduced. As a result, the rotation angle detector 11 can be further downsized.

  In the first to fourth embodiments, the present invention is embodied in, for example, a rotation angle detection device that detects the steering angle of a steering in a vehicle as an absolute value, but the gear stage is changed in the automatic transmission of the vehicle. In some cases, the present invention may be embodied in a rotation angle detection device that detects the operation position of the shift lever operated by the driver. Further, the rotation angle detection device 11 may be used as a means for detecting the operation amount of the brake pedal, the operation amount of the accelerator pedal, and the throttle opening.

  In recent years, a by-wire type steering device (steer-by-wire system) in which a steering wheel and wheels are mechanically separated is known. In this steering device, a rotation angle (steering angle) of a steering shaft that rotates integrally with a steering wheel is detected by a rotation angle detection device, and a steering angle of a wheel is electrically controlled based on the detection result. As such a rotation angle detection device of the by-wire type steering device, the rotation angle detection device 11 of the first to fourth embodiments may be applied.

  In the first to fourth embodiments, the magnets 21, 41, 51, 61 are formed in an annular shape, but may be formed in an irregular shape such as an ellipse. In this way, even if the magnetization angles of the magnetic poles of the magnets 21, 41, 51, 61 are all the same, the detection signals output from the first and second magnetic sensors 23, 24, and thus based on them. The combination of the values of the first and second arctangent signals Sc1, Sc2 can be made different.

  -Moreover, you may make it insert the steering shaft 12 in the position shifted | deviated from the center of the magnet 21,41,51,61. In this way, the magnets 21, 41, 51, 61 rotate eccentrically as the steering shaft 12 rotates. For this reason, even if the magnetization angles of the magnetic poles of the magnets 21, 41, 51, 61 are all the same, the detection signals output from the first and second magnetic sensors 23, 24, and thus the first and The combination of the values of the second arc tangent signals Sc1, Sc2 can be made different.

<Other technical ideas>
(A) In the rotation angle detection device for detecting the rotation angle of the rotating body, the magnet is provided so as to be rotatable integrally with the rotating body, and the N pole and the S pole are alternately provided in the rotating direction, and the magnet A single magnetic sensor that detects a change in the direction of magnetic flux emitted from the magnet or a change in the strength of the magnetic flux generated by the rotation of the magnetic field, and outputs a plurality of detection signals having different phases, and is output from the plurality of magnetic sensors. Calculating means for determining a rotation angle of the rotating body based on a plurality of detection signals, and setting the magnetization pattern of the magnets so that all combinations of detection signal values from the plurality of magnetic sensors are different. The rotation angle detection device designed to do this. Even with this configuration, the same combination does not appear in the combination of the values of the plurality of detection signals output from the magnetic sensor.

  (B) In the rotation angle detection device according to (a) above, the single magnetic sensor includes two sets of magnetoresistive element circuits in which four magnetoresistive elements are connected in a bridge shape, thereby providing a sine signal and Rotation using an MRE sensor that outputs two sets of analog signals (two sine signals and two cosine signals) composed of cosine signals, and the two sets of magnetoresistive element circuits are inclined at 45 ° from each other. Angle detection device. In this way, two sets of analog signals consisting of a sine signal and a cosine signal are output from a single magnetic sensor. Since only a single magnetic sensor needs to be provided in the vicinity of the magnet, the number of components of the rotation angle detection device can be reduced.

FIG. 3 is a front sectional view of the rotation angle detection device according to the first embodiment. (A) is a schematic top view which similarly shows the arrangement | positioning relationship between a magnet and two magnetic sensors, (b) is a list figure of the magnetization angle and polarity of each magnetic pole similarly. The block diagram which similarly shows the electric constitution of a rotation angle detection apparatus. The waveform figure of the arc tangent signal calculated | required based on the detection signal of two magnetic sensors similarly. (A) is a schematic plan view which shows the arrangement | positioning relationship between the magnet and two magnetic sensor in 2nd Embodiment, (b) is a list figure of the magnetization angle and polarity of each magnetic pole similarly. The waveform figure of the arc tangent signal calculated | required based on the detection signal of two magnetic sensors similarly. (A) is a schematic plan view which shows the arrangement | positioning relationship between the magnet and two magnetic sensor in 3rd Embodiment, (b) is a list figure of the magnetization angle and polarity of each magnetic pole similarly. The waveform figure of the arc tangent signal calculated | required based on the detection signal of two magnetic sensors similarly. (A) is a schematic plan view which shows the arrangement | positioning relationship between the magnet and 2 magnetic sensor in 4th Embodiment, (b) is a list figure of the magnetization angle and polarity of each magnetic pole similarly. The waveform figure of the arc tangent signal calculated | required based on the detection signal of two magnetic sensors similarly.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... Rotation angle detection apparatus, 12 ... Steering shaft (rotary body),
21, 41, 51, 61 ... magnets, 23 ... first magnetic sensor, 24 ... second magnetic sensor,
32: Microcomputer (calculation means), P1 to P10: Magnetic poles,
θ1 to θ10: magnetization angle, φ: rotation angle.

Claims (4)

In the rotation angle detection device for detecting the rotation angle of the rotating body,
A magnet that is provided so as to be integrally rotatable with the rotating body, and in which the N pole and the S pole are alternately provided in the rotation direction;
A plurality of magnetic sensors for detecting a change in the direction of magnetic flux emitted from the magnet accompanying the rotation of the magnet or a change in the intensity of the magnetic flux, and outputting a plurality of detection signals having different phases;
Calculating means for obtaining a rotation angle of the rotating body based on a plurality of detection signals output from the plurality of magnetic sensors;
The plurality of magnetic sensors are arranged with their positions relative to the magnets shifted from each other, and the magnetized patterns of the magnets are attached to the magnetic poles so that combinations of detection signal values from the plurality of magnetic sensors are different. A rotation angle detection device in which the magnetic angle is set to gradually increase or decrease in the rotation direction of the rotating body . The rotation angle detection device according to claim 1 ,
The magnet magnetization pattern is a rotation angle detection device in which the magnetization angle of each magnetic pole is increased or decreased in an arithmetic progression in the rotation direction of the rotating body. In the rotation angle detection device for detecting the rotation angle of the rotating body,
A magnet that is provided so as to be integrally rotatable with the rotating body, and in which the N pole and the S pole are alternately provided in the rotation direction;
A plurality of magnetic sensors for detecting a change in the direction of magnetic flux emitted from the magnet accompanying the rotation of the magnet or a change in the intensity of the magnetic flux, and outputting a plurality of detection signals having different phases;
Calculating means for obtaining a rotation angle of the rotating body based on a plurality of detection signals output from the plurality of magnetic sensors;
The plurality of magnetic sensors are arranged so that their positions relative to the magnets are shifted from each other, and the magnetized patterns of the magnets are arranged between adjacent magnetic poles so that combinations of detection signal values from the plurality of magnetic sensors are different . A rotation angle detection device in which the magnetization angles are all set differently . In the rotation angle detection device according to claim 3 ,
In the combination of detection signals from the plurality of magnetic sensors, the magnetization angle of each magnetic pole is set so that the angle at which the same combination appears is not an integer multiple of the detection resolution of the rotation angle of the arithmetic means. Thus, the rotation angle detection device is configured to make all combinations of detection signals from the magnetic sensors different.

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