JP2011080783A - Relative angle detector, rotation angle detector, and power steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technique for detecting a relative rotation angle between two rotary shafts with high accuracy since the rotation angle of a rotary shaft can be detected with high accuracy even if relative displacement arises between a magnet and a magnetic sensor. <P>SOLUTION: This relative angle detector includes a first magnet 10 provided on a first rotary shaft 120 and magnetized circumferentially of the rotary shaft 120, a second magnet 20 provided on a second rotary shaft 130 and magnetized circumferentially of the rotary shaft 130, a plurality of first magnetic sensors 46 disposed at even intervals circumferentially of the rotary shaft 120 so as to confront an outer circumferential surface of the first magnet 10, a plurality of second magnetic sensors 47 disposed at even intervals circumferentially of the rotary shaft 130 so as to confront an outer circumferential surface of the second magnet 20, and a relative angle calculator for calculating a relative angle between the rotary shafts 120 and 130 based on the outputs of the magnetic sensors 46 and 47. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a relative angle detection device, a rotation angle detection device, and a power steering device.

In recent years, as an example of a rotation angle detection device, a relative angle detection device that detects rotational torque applied to a steering wheel to assist steering rotation has been proposed.
For example, Patent Document 1 describes a torque detection device (relative angle detection device) configured as follows. That is, two magnetic rotating bodies that are attached to a rotating shaft connecting the driving side and the load side and separated by a predetermined distance and are provided with a plurality of magnetic bodies having N and S poles on the surface, and magnetic bodies of the two magnetic rotating bodies Provided with a pair of magnetoresistive elements arranged facing each surface, the internal resistance changes in response to the magnetic field of the magnetic material, and separated by half the magnetic pole pitch of the magnetic material, and corresponding magnetic rotation And two magnetic sensors each outputting a two-phase sinusoidal signal that is approximately 90 degrees out of phase with respect to the relative angular displacement with the body. Further, two magnetic rotations are obtained from means for detecting the magnitude of the sinusoidal signals output from the two magnetic sensors, and the two-phase sinusoidal signals having a phase difference of approximately 90 degrees obtained from the respective magnetic sensors. Means for detecting whether the displacement between the body and the corresponding magnetic sensor is in one of four different modes every 90 degrees between 0 and 360 degrees, and the magnitude of the sinusoidal signal and The phase difference between the rotation angles of the two magnetic rotating bodies is obtained from the detected mode, and the load torque acting on the rotating shaft is detected from the phase difference between the rotation angles.

Japanese Patent Publication No. 8-14515

  Even in a device that detects the rotation angle of a rotation shaft using a magnet attached to the rotation shaft and magnetized so that the magnetization direction changes alternately and a magnetic sensor having a magnetoresistive element, the magnet and the magnet It is desirable that the rotation angle of the rotary shaft can be detected with high accuracy even if a relative positional deviation occurs between the sensor and the sensor. Also in an apparatus that detects the relative rotation angle of two rotation shafts, it is desirable to detect the rotation angle of each rotation shaft with high accuracy in order to detect the relative rotation angle with high accuracy.

For this purpose, the present invention is a relative angle detection device for detecting a relative angle between a first rotating shaft and a second rotating shaft, and is provided on the first rotating shaft. A first magnet magnetized in the circumferential direction of the rotating shaft; a second magnet magnetized in the circumferential direction of the second rotating shaft; and the first magnet The plurality of first magnetic sensors arranged at equal intervals in the circumferential direction of the first rotating shaft so as to face the outer peripheral surface of the magnet, and the outer surface of the second magnet A plurality of second magnetic sensors arranged at equal intervals in the circumferential direction of the second rotating shaft;
Relative angle calculation means for calculating a relative angle between the first rotation shaft and the second rotation shaft based on outputs of the plurality of first magnetic sensors and the plurality of second magnetic sensors. This is a relative angle detection device.

Here, the arrangement interval of the plurality of first magnetic sensors is the number obtained by dividing the number of magnetic pole pairs of the first magnet and the number of arrangement of the first magnetic sensor, and the first magnet. It is preferable that the angle interval is obtained by multiplying by the magnetic pole pitch.
The first magnet is magnetized so that the magnetization direction is alternately changed in the circumferential direction, and the first magnetic sensor is formed to extend in the axial direction of the first rotation shaft. It is preferable to have a pair of magnetoresistive elements arranged at intervals of half the magnetic pole pitch of the first magnet.

  In addition, one magnetoresistive effect element group in which one of the pair of magnetoresistive effect elements of the plurality of first magnetic sensors is connected in series and the other magnetoresistive effect element are connected in series. The other magnetoresistive effect element group connected to the one magnetoresistive effect element group and the other magnetoresistive effect element group and the other magnetoresistive effect element group connected to each other. It is preferable that the apparatus further includes a rotation angle detection unit that detects a rotation angle of the first rotation shaft based on an output voltage from a connection portion between the magnetoresistive element group and the other magnetoresistive element group.

  In the first magnetic sensor, a pair of magnetoresistive elements in the first magnetic sensor are connected in series, and a voltage is applied to both ends of the pair of magnetoresistive elements connected in series. In this case, a voltage from the connection portion between the pair of magnetoresistive elements is output, and a rotation angle of the first rotating shaft is detected based on an average value of output voltages from the plurality of first magnetic sensors. It is preferable to further include a rotation angle detection means.

From another point of view, the present invention is a relative angle detection device that detects a relative angle between a first rotation shaft and a second rotation shaft, and is provided on the first rotation shaft. A magnet magnetized in the circumferential direction of the first rotating shaft and an equal interval in the circumferential direction of the first rotating shaft so as to face the outer peripheral surface of the magnet while being provided on the second rotating shaft. A plurality of magnetic sensors arranged in
A relative angle detecting device comprising: a relative angle calculating means for calculating a relative angle between the first rotating shaft and the second rotating shaft based on outputs of the plurality of magnetic sensors.
Here, the arrangement interval of the plurality of magnetic sensors is an angle obtained by multiplying the number obtained by dividing the number of magnetic pole pairs of the magnet and the number of arranged magnetic sensors by the magnetic pole pitch of the magnet. An interval is preferred.

From another point of view, the present invention is a rotation angle detection device for detecting a rotation angle of a rotation shaft, the magnet provided on the rotation shaft and magnetized in the circumferential direction of the rotation shaft, It has a pair of magnetoresistive effect elements formed so as to extend in the axial direction of the rotating shaft and arranged at a half interval of the magnetic pole pitch of the magnet, and so as to face the outer peripheral surface of the magnet. And a plurality of magnetic sensors arranged at equal intervals in the circumferential direction.
Here, the arrangement interval of the plurality of first magnetic sensors is the number obtained by dividing the number of magnetic pole pairs of the first magnet and the number of arrangement of the first magnetic sensor, and the first magnet. It is preferable that the angle interval is obtained by multiplying by the magnetic pole pitch.

  From another point of view, the present invention provides a first rotating shaft connected to a steering wheel, a second rotating shaft connected to the first rotating shaft via a torsion bar, and the first rotating shaft. A first magnet provided on one rotating shaft and magnetized in the circumferential direction of the first rotating shaft; and provided on the second rotating shaft and magnetized in the circumferential direction of the second rotating shaft. A plurality of first magnetic sensors arranged at equal intervals in the circumferential direction of the first rotating shaft so as to face the outer peripheral surface of the first magnet, and the second magnet A plurality of second magnetic sensors arranged at equal intervals in the circumferential direction of the second rotation shaft, the plurality of first magnetic sensors, and the plurality of second Relative angle for calculating the relative angle between the first rotating shaft and the second rotating shaft based on the output of the magnetic sensor A calculation unit, a power steering device, characterized in that it comprises a.

  According to the present invention, it is possible to detect the rotation angle of the rotating shaft with higher accuracy than when the present invention is not employed. Therefore, the relative rotation angle between the two rotation shafts can be detected with high accuracy.

It is sectional drawing of the electric power steering apparatus to which the relative angle detection apparatus which concerns on 1st Embodiment is applied. It is a schematic block diagram of the main components of the relative angle detection apparatus which concerns on 1st Embodiment. It is a schematic block diagram of the relative angle detection apparatus which concerns on 1st Embodiment. It is the figure which simplified and described the circuit structure of the 1st rotation angle detection apparatus and 2nd rotation angle detection apparatus which concern on 1st Embodiment. It is a figure which shows the waveform of the output voltage output from a 1st rotation angle detection apparatus, and the output voltage output from a 2nd rotation angle detection apparatus. It is a schematic block diagram of the relative angle detection apparatus which concerns on 2nd Embodiment. It is sectional drawing of the electric power steering apparatus to which the relative angle detection apparatus which concerns on 3rd Embodiment is applied.

<First Embodiment>
Hereinafter, the first embodiment will be described in detail with reference to the accompanying drawings.
FIG. 1 is a cross-sectional view of an electric power steering apparatus 100 to which a relative angle detection apparatus 1 according to the first embodiment is applied.
The relative angle detection device 1 is a device that detects a relative angle between a first rotation shaft 120 that is rotatably supported by the housing 110 and a second rotation shaft 130 that is also rotatably supported by the housing 110. .

The housing 110 is a member that is fixed to a body frame (hereinafter also referred to as “vehicle body”) of a vehicle such as an automobile, and the first housing 111 and the second housing 112 are coupled by, for example, a bolt or the like. Configured.
The first rotating shaft 120 is a rotating shaft to which, for example, a steering wheel is connected, and is rotatably supported by the first housing 111 via a bearing 113.

The second rotating shaft 130 is coaxially coupled to the first rotating shaft 120 via a torsion bar 140 and is rotatably supported by the second housing 112 via a bearing 114. A pinion 131 formed on the second rotating shaft 130 meshes with a rack (not shown) of a rack shaft (not shown) connected to the wheel. Then, the rotary motion of the second rotary shaft 130 is converted into a linear motion of the rack shaft through the pinion 131 and the rack, and the wheels are steered.
A worm wheel 150 is fixed to the second rotating shaft 130 by, for example, press fitting. The worm wheel 150 meshes with a worm gear 161 connected to the output shaft of the electric motor 160 fixed to the second housing 112.

  The electric power steering apparatus 100 configured as described above detects the relative angle between the first rotating shaft 120 and the second rotating shaft 130 by the relative angle detecting device 1, and steers based on the detected relative angle. Recognizes the steering torque applied to the wheel. Then, the electric motor 160 is driven based on the recognized steering torque, and the torque generated by the electric motor 160 is transmitted to the second rotating shaft 130 via the worm gear 161 and the worm wheel 150. Thereby, the torque generated by the electric motor 160 assists the driver's steering force applied to the steering wheel.

Hereinafter, the relative angle detection device 1 will be described in detail.
The relative angle detection device 1 includes a cylindrical first magnet 10 attached to a first rotating shaft 120 and a magnetic field generated by the first magnet 10 that is disposed to face the outer peripheral surface of the first magnet 10. And a first rotation angle detection device 41 that detects the rotation angle of the first rotation shaft 120 based on the first rotation angle detection device 41. Further, the relative angle detection / detection device 1 is arranged so as to be opposed to the cylindrical second magnet 20 attached to the second rotating shaft 130 and the outer peripheral surface of the second magnet 20, and the second magnet 20 is generated. And a second rotation angle detector 42 that detects the rotation angle of the second rotation shaft 130 based on the magnetic field to be generated. Further, the relative angle detection device 1 is based on the output values from the first rotation angle detection device 41 and the second rotation angle detection device 42, and the relative angle between the first rotation shaft 120 and the second rotation shaft 130. The relative angle calculation unit 50 is calculated.

FIG. 2 is a schematic configuration diagram of main components of the relative angle detection device 1 according to the first embodiment.
The first magnet 10 and the second magnet 20 are cylindrical, and as shown in FIG. 2, the magnetization direction is a magnetic pole pitch λ in the circumferential direction of the first rotating shaft 120 and the second rotating shaft 130. It is magnetized so as to change alternately. The first magnet 10 is attached to the first rotating shaft 120 and rotates together with the first rotating shaft 120. The second magnet 20 is attached to the second rotating shaft 130 and rotates together with the second rotating shaft 130.

The first rotation angle detection device 41 includes a plurality of first magnetic sensors 46 having a pair of magnetoresistive elements that are arranged at intervals of 1/2 (half) of the magnetic pole pitch λ and whose electric resistance varies with an external magnetic field. (In FIG. 2, four cases are illustrated). Each of the plurality of first magnetic sensors 46 has a first housing so as to face the outer peripheral surface of the first magnet 10 through a predetermined gap in the rotational radius direction of the first rotating shaft 120. 111 is fixed. Further, the plurality of first magnetic sensors 46 are arranged at equal intervals in the circumferential direction of the first rotation shaft 120. And the arrangement | positioning space | interval is set to the angle which satisfy | fills Formula (1).
Pθ1 = n × λ / N (1)
Here, Pθ1 is the arrangement pitch angle of the first magnetic sensor 46, N is the number of arrangement of the first magnetic sensor 46, and n is the number of magnetic pole pairs. However, N is an integer of 2 or more, and a value that satisfies n / N = integer is selected.

  For example, when the number of first magnetic sensors 46 to be arranged is four (N = 4) and the number of magnetic pole pairs is 100 (n = 100), the magnetic pole pitch λ = 360/100 = 3.6 (degrees). From Equation (1), Pθ1 = 3.6 × 100/4 = 90 (degrees). Therefore, in such a case, four first magnetic sensors 46 are arranged at intervals of 90 degrees.

Then, a circuit for detecting the rotation angle of the first rotating shaft 120 is formed using the plurality of first magnetic sensors 46.
FIG. 3 is a schematic configuration diagram of the relative angle detection device 1 according to the first embodiment. In order to make the configuration easy to understand, the circular shape has been developed in a plane. FIG. 4 is a diagram illustrating a simplified circuit configuration of the first rotation angle detection device 41 and the second rotation angle detection device 42 according to the first embodiment.
The Nth first magnetic sensor 46N has a pair of magnetoresistive elements 46N-a and 46N-b arranged at intervals of ½ of the magnetic pole pitch λ. The magnetoresistive elements 46N-a and 46N-b are formed on the control substrate by a known method such as vapor deposition or etching so as to extend in a direction perpendicular to the moving direction of the first magnet 10. A pair of magnetoresistive elements of the N first magnetic sensors 46 are connected by wiring as shown in FIG. That is, one of the N magnetoresistive elements of the first magnetic sensor 46 is connected in series (461-a to 46N-a are connected in series), and the other one is connected. Magnetoresistive elements are connected in series (461-b to 46N-b are connected in series). Hereinafter, the magnetoresistive effect elements 461-a to 46N-a connected in series are referred to as “one magnetoresistive effect element group 46a”, and the magnetoresistive effect elements 461-b to 46N-b are referred to as “the other magnetoresistive effect elements 46a”. This is referred to as a magnetoresistive effect element group 46b ". Then, one terminal of one magnetoresistive effect element group 46a and one terminal of the other magnetoresistive effect element group 46b are connected and this connecting portion is connected to an output terminal, and two magnetoresistive effect element groups 46a, A voltage V is applied between the other terminals of 46b. That is, when described in a simplified manner, a pair of magnetoresistive effect elements of the N first magnetic sensors 46 are connected as shown in FIG. In this circuit, an output voltage obtained when the voltage V is applied is EA1.

  The second rotation angle detection device 42 includes a plurality of second magnetic sensors 47 having a pair of magnetoresistive elements that are arranged at an interval of (half) 1/2 of the magnetic pole pitch λ and whose electric resistance varies with an external magnetic field. (In FIG. 2, four cases are illustrated). Each of the plurality of second magnetic sensors 47 is disposed in the rotational radius direction of the second rotating shaft 130 so as to face the outer peripheral surface of the second magnet 20 via a predetermined gap. . Further, the plurality of second magnetic sensors 47 are arranged at equal intervals in the circumferential direction of the second rotation shaft 130. And the arrangement | positioning space | interval is set to the angle which satisfy | fills Formula (1) mentioned above.

  Then, a circuit for detecting the rotation angle of the second rotating shaft 130 is formed using the plurality of second magnetic sensors 47. The configuration of this circuit is the same as that of the first rotation angle detection device 41. That is, one of the pair of magnetoresistive elements of the N second magnetic sensors 47 is connected in series (471-a to 47N-a are connected in series), and the other one is connected. Magnetoresistive elements are connected in series (471-b to 47N-b are connected in series). Hereinafter, the magnetoresistive effect elements 471-a to 47N-a connected in series are referred to as “one magnetoresistive effect element group 47a”, and the magnetoresistive effect elements 471-b to 47N-b are referred to as “the other magnetoresistive effect elements 47a”. This is referred to as a magnetoresistive effect element group 47b ". Then, one terminal of one magnetoresistive effect element group 47a and one terminal of the other magnetoresistive effect element group 47b are connected and this connecting portion is connected to an output terminal, and two magnetoresistive effect element groups 47a, A voltage V is applied between the other terminals of 47b. That is, in a simplified manner, a pair of magnetoresistive effect elements of N second magnetic sensors 47 are connected as shown in FIG. In this circuit, the output voltage obtained when the voltage V is applied is EA2.

  The relative angle calculation unit 50 receives the output voltage EA1 output from the first rotation angle detection device 41 and the output voltage EA2 output from the second rotation angle detection device 42. Then, the relative angle calculation unit 50 determines the relative rotation angle Δθ that is the difference between the rotation angle of the first rotation shaft 120 and the rotation angle of the second rotation shaft 130 based on the difference between the output voltage EA1 and the output voltage EA2. Is calculated. More specifically, as described below.

FIG. 5 is a diagram illustrating waveforms of the output voltage EA1 output from the first rotation angle detection device 41 and the output voltage EA2 output from the second rotation angle detection device 42.
As described above, the plurality of first magnetic sensors 46 and the plurality of second magnetic sensors 47 are arranged at intervals of an integral multiple of the magnetic pole pitch λ, as derived from the above-described equation (1). Therefore, one of the magnetoresistive elements (461-a to 46N-a) connected in series among the pair of magnetoresistive elements of the N first magnetic sensors 46 is an integer of the magnetic pole pitch λ. When the first rotating shaft 120 rotates with the double spacing, the magnetoresistance effect elements 461-a to 46N-a change in electrical resistance at the same timing. Similarly, the other magnetoresistive effect elements (461-b to 46N-b) of the N first magnetic sensors 46 connected in series are arranged at intervals of an integral multiple of the magnetic pole pitch λ. Therefore, when the 1st rotating shaft 120 rotates, these magnetoresistive effect elements 461-b-46N-b change an electrical resistance at the same timing. One magnetoresistive effect element (461-a to 46N-a) and the other magnetoresistive effect element (461-b to 46N-b) are shifted from each other by a half of the magnetic pole pitch λ. Therefore, the output voltage EA1 output from the first rotation angle detection device 41 has a waveform as shown in FIG.

That is, when the resistance value of the magnetoresistive effect element included in one magnetoresistive effect element group 46a increases, the resistance value of the magnetoresistive effect element included in the other magnetoresistive effect element group 46b decreases, When the resistance value of the magnetoresistive effect element included in the effect element group 46a decreases, the resistance value of the magnetoresistive effect element included in the other magnetoresistive effect element group 46b increases. Therefore, the resistance value of one magnetoresistive element group 46a and the resistance value of the other magnetoresistive element group 46b change according to the rotation angle of the first rotating shaft 120, and the first rotation angle detecting device. The output voltage EA1 output from 41 has a waveform as shown in FIG.
Similarly, the output voltage EA2 output from the second rotation angle detection device 42 has a sine waveform as shown in FIG.
The relative rotation angle Δθ between the first rotating shaft 120 and the second rotating shaft 130 can be detected by detecting the difference between the output voltage EA1 and the output voltage EA2 at the zero cross.

  Here, since the resistance value of the magnetoresistive element of the first magnetic sensor 46 (second magnetic sensor 47) changes according to the magnitude of the magnetic field, the first magnetic sensor 46 (second magnetic sensor). 47) and the first magnet 10 (second magnet 20) deviate from a predetermined target distance, the pair of magnetoresistive effects of the first magnetic sensor 46 (second magnetic sensor 47). The change in the resistance value of the element varies with respect to the case where the relative distance is the target distance. For example, the first magnet 10 or the second magnet 20 is eccentrically attached to the first magnetic sensor 46 (second magnetic sensor 47) fixed to the housing 110. When the relative distance between the sensor 46 (second magnetic sensor 47) and the first magnet 10 (second magnet 20) becomes larger than the target distance, the resistance value of the pair of magnetoresistive elements changes. However, it becomes smaller compared with the case where the relative distance is the target distance. As a result, it becomes difficult to detect the change in the output voltage according to the change in the resistance value of the pair of magnetoresistive elements with high accuracy. Therefore, for example, if the rotation angle of the first rotating shaft 120 (second rotating shaft 130) is detected using one first magnetic sensor 46 (second magnetic sensor 47), the rotation is performed with high accuracy. There is a possibility that the angle cannot be detected.

On the other hand, in the relative angle detection device 1 configured as described above, a plurality of first magnetic sensors 46 (first magnets 46) are arranged so as to face the outer peripheral surface of the first magnet 10 (second magnet 20). Two magnetic sensors 47) are arranged at equal intervals, and a plurality of magnetoresistive elements arranged at equal intervals are connected in series. Therefore, for example, the first magnet 10 (second magnet 20) is eccentrically attached to the housing 110, and one first of the plurality of first magnetic sensors 46 (second magnetic sensors 47) is attached. Even if the resistance value of the magnetoresistive effect element of the magnetic sensor 46 (second magnetic sensor 47) decreases, the resistance value of the magnetoresistive effect element of the other first magnetic sensor 46 (second magnetic sensor 47) remains. growing. Therefore, the resistance value of the entire magnetoresistive element group 46a (one magnetoresistive element group 47a) and the other magnetoresistive element group 46b (the other magnetoresistive element group 47b), and the first The deviation from the resistance value when the magnet 10 (second magnet 20) is attached according to the target is smaller than in the case where one first magnetic sensor 46 (second magnetic sensor 47) is used. As the number of first magnetic sensors 46 (second magnetic sensors 47) increases, the resistance value approaches that when the first magnets 10 (second magnets 20) are attached as intended.
Therefore, by using the relative angle detection device 1 according to the present embodiment, the rotation angle of the first rotation shaft 120 and the rotation angle of the second rotation shaft 130 can be detected with high accuracy, and the first The rotation angle of the rotation shaft 120 and the relative rotation angle between the second rotation shaft 130 can be detected with high accuracy.

  Since the first rotating shaft 120 and the second rotating shaft 130 are twisted in proportion to the steering torque, the electric power is based on the relative rotation angle between the first rotating shaft 120 and the second rotating shaft 130. It becomes possible to detect the steering torque of the vehicle to which the steering device 100 is applied. For example, the relative rotation angle detected by the relative angle detection device 1 is substituted into a map indicating the correspondence between the relative rotation angle and the steering torque, which is created based on an empirical rule and stored in a storage area such as a ROM. Thus, the steering torque may be calculated.

<Second Embodiment>
The relative angle detection device 1 according to the second embodiment is different from the relative angle detection device 1 according to the first embodiment by using a plurality of first magnetic sensors 46 and second magnetic sensors 47. The method for detecting the rotation angle of the rotation shaft 120 and the rotation angle of the second rotation shaft 130 is different. Hereinafter, different points will be described, and the same points as in the first embodiment will be omitted.

FIG. 6 is a schematic configuration diagram of the relative angle detection device 1 according to the second embodiment. In order to make the configuration easy to understand, the circular shape has been developed in a plane.
In the first rotation angle detection device 41 according to the second embodiment, one terminal of a pair of magnetoresistive effect elements of each first magnetic sensor 46 (second magnetic sensor 47) is connected to each other. The connecting portion is connected to the output terminal, and a voltage V is applied between the other terminals of the pair of magnetoresistive elements. For example, in the N-th first magnetic sensor 46N, as shown in FIG. 6, one terminal of a pair of magnetoresistive effect elements 46N-a and 46N-b is connected to each other and this connection portion is used as an output terminal. By connecting and applying a voltage V between the other terminals of the pair of magnetoresistive elements 46N-a and 46N-b, an output voltage EA1-N is output from the Nth first magnetic sensor 46N.
Then, the relative angle calculation unit 50 acquires the output voltages EA1-1 to EA1-N from the N first magnetic sensors 46, and divides the sum of these by N to obtain the N first voltages. The average voltage EA1 (= (EA1-1 + EA1-2 +... + EA1-N) / N) of the output voltage from the magnetic sensor 46 is calculated.

Similarly, for example, in the N-th second magnetic sensor 47N, one terminal of the pair of magnetoresistive effect elements 47N-a and 47N-b is connected to each other, and this connection portion is connected to the output terminal. The voltage V is applied between the other terminals of the magnetoresistive effect elements 47N-a and 47N-b, thereby outputting the output voltage EA2-N from the Nth second magnetic sensor 47N.
Then, the relative angle calculation unit 50 acquires the output voltages EA2-1 to EA2-N from the N second magnetic sensors 47, and divides the sum of these by N to obtain N second voltages. An average voltage EA2 (= (EA2-1 + EA2-2 +... + EA2-N) / N) of the output voltage from the magnetic sensor 47 is calculated.

Then, the relative angle calculation unit 50 detects the relative rotation angle between the first rotation shaft 120 and the second rotation shaft 130 by detecting the difference between the average voltage EA1 and the average voltage EA2.
In the relative angle detection device 1 according to the second embodiment configured as described above, for example, the first magnet 10 (the first magnet 10 is attached to the housing 110) as in the relative angle detection device 1 according to the first embodiment. The second magnet 20) is eccentrically mounted, and the output voltage from one first magnetic sensor 46 (second magnetic sensor 47) of the plurality of first magnetic sensors 46 (second magnetic sensor 47). Even if becomes smaller, the output voltage from the other first magnetic sensor 46 (second magnetic sensor 47) becomes larger. Therefore, the average voltages EA1 and EA2 as a whole of the plurality of first magnetic sensors 46 and the second magnetic sensors 47, and the average voltage when the first magnet 10 or the second magnet 20 is attached as intended. The deviation from EA1 and EA2 is smaller than in the case where one first magnetic sensor 46 (second magnetic sensor 47) is used. As the number of the first magnetic sensors 46 (second magnetic sensors 47) increases, the average voltage EA1 (EA2) when the first magnet 10 (second magnet 20) is attached according to the target is obtained. Approaching.

Therefore, by using the relative angle detection device 1 according to the second embodiment, the rotation angle of the first rotation shaft 120 and the rotation angle of the second rotation shaft 130 can be detected with high accuracy, and the first The relative rotation angle between the rotation shaft 120 and the second rotation shaft 130 can be detected with high accuracy.
Further, by detecting the steering torque based on the relative rotation angle detected by the relative angle detection device 1 according to the second embodiment, it becomes possible to detect the steering torque with high accuracy.

<Third Embodiment>
In the relative angle detection device 1 according to the first embodiment and the second embodiment, the rotation angle of the first rotation shaft 120 is detected by the first rotation angle detection device 41 and the second rotation shaft is detected. The rotation angle 130 is detected by the second rotation angle detection device 42, and the first rotation shaft 120 and the second rotation angle are detected based on the detection values of the first rotation angle detection device 41 and the second rotation angle detection device 42. The relative rotation angle with respect to the rotation shaft 130 was detected. In contrast, in the third embodiment, the first rotating shaft 120 with respect to the second rotating shaft 130 includes a magnet attached to the first rotating shaft 120 and a magnetic sensor attached to the second rotating shaft 130. By detecting the rotation angle, the relative rotation angle between the first rotation shaft 120 and the second rotation shaft 130 is detected. Below, the same code | symbol is shown about the thing of the same function among the components of the relative angle detection apparatus 1 which concerns on 1st Embodiment or 2nd Embodiment, and the detailed description is abbreviate | omitted.

FIG. 7 is a cross-sectional view of an electric power steering device 100 to which the relative angle detection device 1 according to the third embodiment is applied.
As shown in FIG. 7, in the relative angle detection device 1 according to the third embodiment, a plurality of first magnetic sensors 46 are connected to each other via a bracket 49 fixed to the second rotation shaft 130. The rotary shaft 120 is arranged so as to face the outer peripheral surface of the first magnet 10 through a predetermined gap in the rotational radius direction. Each of the plurality of first magnetic sensors 46 is arranged at equal intervals in the circumferential direction of the first rotating shaft 120 at an angle that satisfies the above formula (1). That is, the plurality of first magnetic sensors 46 are attached to the bracket 49 fixed to the second rotating shaft 130.

  When a plurality of first magnetic sensors 46 are connected in the same manner as the first rotation angle detection device 41 according to the first embodiment, and the voltage V is applied in the circuit shown in FIG. The obtained output voltage EA1 is output to the relative angle calculation unit 50. Then, the relative angle calculation unit 50 determines the relative rotation angle between the first rotation shaft 120 and the second rotation shaft 130 based on the difference between the output voltage EA1 and the output voltage in the reference state where no steering torque is generated. Is detected.

  Alternatively, the plurality of first magnetic sensors 46 are configured like the first rotation angle detection device 41 according to the second embodiment, and output from each of the plurality of first magnetic sensors 46 to the relative angle calculation unit 50. Output voltage. Then, the relative angle calculation unit 50 calculates the average voltage EA1 of the output voltages (EA1-1, EA1-2,... EA1-N) from the N first magnetic sensors 46, and the average voltage EA1. And the relative rotation angle between the first rotating shaft 120 and the second rotating shaft 130 is detected based on the difference between the output voltage in the reference state in which no steering torque is generated.

  Even in such a configuration, it is possible to detect the rotation angle of the first rotation shaft 120 and the relative rotation angle between the second rotation shaft 130 with high accuracy. Further, by detecting the steering torque based on the relative rotation angle detected by the relative angle detection device 1 according to the third embodiment, it becomes possible to detect the steering torque with high accuracy.

  In the above configuration, the first magnet 10 attached to the first rotating shaft 120 and the plurality of first magnetic sensors 46 attached to the second rotating shaft 130 are connected to the second rotating shaft 130. The rotation angle of one rotation shaft 120 is detected, but the second magnet 20 attached to the second rotation shaft 130 and the plurality of second magnetic sensors 47 attached to the first rotation shaft 120 By detecting the rotation angle of the second rotation shaft 130 with respect to the first rotation shaft 120, the relative rotation angle between the first rotation shaft 120 and the second rotation shaft 130 may be detected.

DESCRIPTION OF SYMBOLS 1 ... Relative angle detection apparatus, 10 ... 1st magnet, 20 ... 2nd magnet, 41 ... 1st rotation angle detection apparatus, 42 ... 2nd rotation angle detection apparatus, 46 ... 1st magnetic sensor, 47 DESCRIPTION OF SYMBOLS ... 2nd magnetic sensor, 49 ... Bracket, 50 ... Relative angle calculating part, 100 ... Electric power steering apparatus, 110 ... Housing, 120 ... 1st rotating shaft, 130 ... 2nd rotating shaft, 140 ... Torsion bar, 150 ... Worm wheel, 160 ... Electric motor

Claims (10)

A relative angle detection device for detecting a relative angle between a first rotation axis and a second rotation axis,
A first magnet provided on the first rotating shaft and magnetized in a circumferential direction of the first rotating shaft;
A second magnet provided on the second rotating shaft and magnetized in a circumferential direction of the second rotating shaft;
A plurality of first magnetic sensors arranged at equal intervals in the circumferential direction of the first rotating shaft so as to face the outer peripheral surface of the first magnet;
A plurality of second magnetic sensors arranged at equal intervals in the circumferential direction of the second rotating shaft so as to face the outer peripheral surface of the second magnet;
A relative angle calculating means for calculating a relative angle between the first rotating shaft and the second rotating shaft based on outputs of the plurality of first magnetic sensors and the plurality of second magnetic sensors;
A relative angle detection device comprising:   The arrangement intervals of the plurality of first magnetic sensors are the number obtained by dividing the number of magnetic pole pairs of the first magnet and the number of arrangements of the first magnetic sensor, and the magnetic pole pitch of the first magnet. The relative angle detection device according to claim 1, wherein the angle interval is obtained by multiplying. The first magnet is magnetized so that the magnetization direction is alternately changed in the circumferential direction,
The first magnetic sensor has a pair of magnetoresistive elements formed so as to extend in the axial direction of the first rotating shaft and arranged at half the magnetic pole pitch of the first magnet. The relative angle detection device according to claim 1 or 2, characterized in that   One magnetoresistive effect element group in which one magnetoresistive effect element of the pair of magnetoresistive effect elements of the plurality of first magnetic sensors is connected in series, and the other magnetoresistive effect element are connected in series. The other magnetoresistive element group, the one magnetoresistive element group when the one magnetoresistive element group and the other magnetoresistive element group are connected and a voltage is applied to both ends thereof. 4. A rotation angle detecting means for detecting a rotation angle of the first rotation shaft based on an output voltage from a connection portion between the effect element group and the other magnetoresistive effect element group. The relative angle detection device described in 1. The first magnetic sensor is configured such that a pair of magnetoresistive elements in the first magnetic sensor are connected in series, and a voltage is applied to both ends of the pair of magnetoresistive elements connected in series. Output the voltage from the connection between the pair of magnetoresistive elements,
4. The relative angle according to claim 3, further comprising a rotation angle detection unit that detects a rotation angle of the first rotation shaft based on an average value of output voltages from the plurality of first magnetic sensors. 5. Detection device. A relative angle detection device for detecting a relative angle between a first rotation axis and a second rotation axis,
A magnet provided on the first rotating shaft and magnetized in a circumferential direction of the first rotating shaft;
A plurality of magnetic sensors provided on the second rotating shaft and arranged at equal intervals in the circumferential direction of the first rotating shaft so as to face the outer peripheral surface of the magnet;
A relative angle calculating means for calculating a relative angle between the first rotating shaft and the second rotating shaft based on outputs of the plurality of magnetic sensors;
A relative angle detection device comprising:   The arrangement interval of the plurality of magnetic sensors is an angular interval obtained by multiplying the number obtained by dividing the number of magnetic pole pairs of the magnet and the arrangement number of the magnetic sensor by the magnetic pole pitch of the magnet. The relative angle detection device according to claim 6. A rotation angle detection device for detecting a rotation angle of a rotation shaft,
A magnet provided on the rotating shaft and magnetized in the circumferential direction of the rotating shaft;
The rotating shaft has a pair of magnetoresistive effect elements formed so as to extend in the axial direction of the rotating shaft and arranged at a half interval of the magnetic pole pitch of the magnet, and facing the outer peripheral surface of the magnet. A plurality of magnetic sensors arranged at equal intervals in the circumferential direction of
A rotation angle detection device comprising:   The arrangement intervals of the plurality of first magnetic sensors are the number obtained by dividing the number of magnetic pole pairs of the first magnet and the number of arrangements of the first magnetic sensor, and the magnetic pole pitch of the first magnet. The relative angle detection device according to claim 1, wherein the angle interval is obtained by multiplying. A first rotating shaft coupled to the steering wheel;
A second rotating shaft coupled to the first rotating shaft via a torsion bar;
A first magnet provided on the first rotating shaft and magnetized in a circumferential direction of the first rotating shaft;
A second magnet provided on the second rotating shaft and magnetized in a circumferential direction of the second rotating shaft;
A plurality of first magnetic sensors arranged at equal intervals in the circumferential direction of the first rotating shaft so as to face the outer peripheral surface of the first magnet;
A plurality of second magnetic sensors arranged at equal intervals in the circumferential direction of the second rotating shaft so as to face the outer peripheral surface of the second magnet;
A relative angle calculating means for calculating a relative angle between the first rotating shaft and the second rotating shaft based on outputs of the plurality of first magnetic sensors and the plurality of second magnetic sensors;
A power steering apparatus comprising:

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