JP5001309B2 - Detection device and power steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technology achieving a compact and easy-to-incorporate structure and increasing detection accuracy. <P>SOLUTION: This system includes a first magnet 10 disposed in a first rotation axis, a first gear 20 to be fixed to a housing, a second gear 30 that revolves about the axial center of a second rotation axis as the rotation center and rotates by torque applied by the first gear 20 as the second rotation axis connected to the first rotation axis rotates, a third gear 40 that has the number of teeth different from that of the second gear 30, and revolves about the axial center of the second rotation axis as the rotation center and rotates by torque applied by the first gear 20 as the second rotation axis rotates, a relative angle detecting means that is fixed to the second rotation axis and detects the relative angle of the first rotation axis to the second rotation axis based on a magnetic field generated from the first magnet 10, and a rotation angle detecting means for detecting the rotation angle of the second rotation axis based on the angle of the rotation of the second gear 30 and the angle of the rotation of the third gear 40. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a detection device and a power steering device that detect a rotation angle of a rotation shaft and a relative angle between two rotation shafts.

For example, a device has been proposed that detects rotational torque applied to a steering wheel to assist steering rotation, and detects the rotational angle of the steering wheel.
For example, a rotation angle / torque detection device described in Patent Document 1 includes a first rotation shaft that rotates in conjunction with steering, first and second detection bodies that rotate in conjunction with the rotation shaft, and detection of these. First and second detection means for detecting the rotation of the body as a detection signal. Also, a second rotating shaft connected to the first rotating shaft via a torsion bar, and third and fourth detecting means for detecting the rotation of these rotating shafts as detection signals are provided.

JP 2005-257364 A

  The rotation angle / torque detection device described in Patent Literature 1 includes first and second detection bodies that rotate in conjunction with a first rotation shaft, and detects the rotation of the first and second detection bodies. The rotation angle detection device is configured using the first and second detection means for detecting as follows. Further, the torque detector is configured by arranging two means for detecting the rotation of the first rotating shaft and the second rotating shaft as detection signals in the axial direction. Therefore, since many components must be arranged in the radial direction and axial direction of the rotating shaft, it is structurally difficult to form a unit as a device for detecting the rotation angle and torque, and it is difficult to incorporate it into a vehicle body or the like. It becomes difficult. In addition, the overall size of the apparatus becomes large.

Further, when two detection means are used to detect torque, there is a possibility that torque detection cannot be performed with high accuracy unless both detection means are capable of detection with very high accuracy.
Therefore, the present invention is to provide a detection device that is compact and easy to incorporate and has high detection accuracy.

  For this purpose, the present invention detects the relative angle between the first rotation shaft rotatably supported by the housing and the second rotation shaft rotatably supported by the housing, and the second rotation shaft. A detection device for detecting a rotation angle of a rotation shaft, wherein a first magnet provided on the first rotation shaft, a first gear fixed to the housing, and a rotation of the second rotation shaft. Along with the rotation of the second rotation shaft, the second gear rotates while being revolved around the axis of the second rotation shaft and the rotational force is applied by the first gear. A third gear having a number of teeth different from the number of teeth of the second gear, revolving around the axis of the second rotating shaft while being revolved while being rotated by the first gear. The magnetic field generated from the first magnet is fixed to the second rotating shaft. Therefore, based on the relative angle detecting means for detecting the relative angle between the first rotating shaft and the second rotating shaft, the rotation angle of the second gear and the rotation angle of the third gear. And a rotation angle detection means for detecting the rotation angle of the second rotation shaft.

Here, the first magnet has N poles and S poles alternately arranged on the outer peripheral surface, and the relative angle detection means is arranged outside the outer peripheral surface of the first magnet, It is preferable to include a first magnetoresistive element having a magnetic body extending perpendicularly to the axis of the first rotating shaft.
And a second magnet that rotates together with the second gear, and a third magnet that rotates together with the third gear, and the rotation angle detecting means is generated from the second magnet. A second magnetoresistive element that detects the rotation angle of the second gear based on the magnetic field, and a second magnetoresistive element that detects the rotation angle of the third gear based on the magnetic field generated from the third magnet. It is preferable that the rotation angle of the second rotating shaft is detected based on the value detected by the second magnetoresistive element and the third magnetoresistive element. .

In addition, it is preferable that the first magnetoresistive element, the second magnetoresistive element, and the third magnetoresistive element are mounted on the same printed circuit board.
It is preferable that the apparatus further includes a support member that supports at least one of the second gear and the third gear so as to be capable of rotating, and is fixed to the second rotation shaft.
In addition, it further includes a support member that rotatably supports at least one of the second gear and the third gear and is fixed to the second rotating shaft, and the printed circuit board is attached to the support member. It is preferred that it is fixed.
Further, it is preferable that the second gear rotates in mesh with the first gear, and the third gear rotates in mesh with the first gear or the second gear.

  From another point of view, the present invention detects the relative angle between the first rotation shaft that is rotatably supported by the housing and the second rotation shaft that is rotatably supported by the housing, and the second rotation shaft. A rotation angle of the rotation axis of the second rotation shaft with the rotation of the first gear fixed to the housing and the rotation of the second rotation shaft. As the second gear rotates and revolves with the rotation of the first gear, the second gear rotates with the axis of the second rotation shaft as the center of rotation. The first gear rotates while being rotated by the first gear and is fixed to the second rotating shaft, the third gear having a number of teeth different from the number of teeth of the second gear, and the first gear. Based on a magnetic field generated from a first magnet provided on the rotation shaft of the first magnet. Relative angle detection means for detecting a relative angle between the rotation axis of the second gear and the second rotation axis, and the second rotation axis based on the rotation angle of the second gear and the rotation angle of the third gear. And a rotation angle detecting means for detecting a rotation angle of the rotation shaft.

  From another point of view, the present invention provides a first rotating shaft that is rotatably supported by a housing and coupled to a steering wheel, and is rotatably supported by the housing and is connected to the first via a torsion bar. A second rotating shaft coupled to the first rotating shaft, a first magnet provided on the first rotating shaft, a first gear fixed to the housing, and rotation of the second rotating shaft. Along with the rotation of the second rotation shaft, the second gear rotating around the axis of the second rotation shaft while rotating around the second rotation shaft and rotating by the first gear. A third gear having a number of teeth different from the number of teeth of the second gear, revolving around the axis of the second rotation shaft while being revolved while being rotated by the first gear. And fixed to the second rotating shaft, from the first magnet A relative angle detecting means for detecting a relative angle between the first rotating shaft and the second rotating shaft based on a generated magnetic field; a rotation angle of the second gear; and a rotation of the third gear. And a rotation angle detecting means for detecting a rotation angle of the second rotation shaft based on the angle of the power steering device.

  According to the present invention, a compact and easy-to-assemble structure can be achieved. Moreover, detection accuracy can be increased.

The best mode (embodiment) for carrying out the present invention will be described below in detail with reference to the accompanying drawings.
FIG. 1 is a cross-sectional view of an electric power steering device 100 to which a detection device 1 according to an embodiment is applied. FIG. 2 is a perspective view of the detection apparatus 1 according to the embodiment.
The detection device 1 detects the relative angle between the first rotating shaft 120 rotatably supported by the housing 110 and the second rotating shaft 130 also rotatably supported by the housing 110 and performs the second rotation. It is a device that detects the rotation angle of the shaft 130.

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 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 device 100 configured as described above detects the steering torque applied to the steering wheel by the detection device 1, drives the electric motor 160 based on the detected torque, and generates 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.

Below, the detection apparatus 1 is explained in full detail.
The detection device 1 includes a first magnet 10 attached to the first rotating shaft 120 and a first gear 20 fixed to the housing 110. In addition, the detecting device 1 rotates the second gear 30 that rotates around the first gear 20 while rotating around the axis of the second rotating shaft 130 as the second rotating shaft 130 rotates. Have. Further, as the second rotation shaft 130 rotates, the detection device 1 rotates while meshing with the first gear 20 while revolving around the axis of the second rotation shaft 130 as the rotation center, and the second gear 30. The third gear 40 has a number of teeth different from the number of teeth.

The first magnet 10 has a donut shape, and the first rotating shaft 120 is fitted inside the first magnet 10. N poles and S poles are alternately arranged at least on the outer peripheral surface.
The first gear 20 is a gear provided on the entire inner peripheral surface of the upper portion of the flat cable cover 50. The flat gear cover 50 is fixed to the second housing 112 of the housing 110, so that the first gear 20 is fixed to the housing 110.

  As an aspect for fixing the flat cable cover 50 to the housing 110, the following aspects can be exemplified. That is, on the outer peripheral surface of the flat cable cover 50, a plurality of convex portions 50a (four in this embodiment at intervals of 90 degrees) are formed to extend outward at equal intervals in the circumferential direction. On the other hand, the same number of concave portions 112a as the convex portions 50a are formed in the second housing 112 of the housing 110 in which the convex portions 50a are fitted. Then, the convex portion 50 a of the flat cable cover 50 is fitted into the concave portion 112 a formed in the second housing 112, thereby positioning the second rotary shaft 130 in the rotational direction. Then, the second rotating shaft 130 is positioned in the axial direction by pressing the upper surface of the flat cable cover 50 with the first housing 111.

The detection device 1 has a base 60 that is fixed to the second rotating shaft 130 and rotates together with the second rotating shaft 130. The second gear 30 and the third gear 40 are rotatably supported by the base 60. In other words, the second gear 30 and the third gear 40 are provided to be rotatable about the axis of the second rotating shaft 130 with respect to the flat cable cover 50 fixed to the housing 110. .
A cylindrical second magnet 30a having a semi-cylindrical N pole and a semi-cylindrical S pole is mounted inside the second gear 30 by insert molding, for example. A third cylindrical magnet 40a having a semi-cylindrical N-pole and a semi-cylindrical S-pole is mounted inside the third gear 40 by insert molding, for example.

  Examples of the aspect in which the second gear 30 is rotatably supported on the base 60 include the following aspects. As shown in FIG. 1, a cylindrical recess 60a is provided in the base 60, and a bearing 61 is mounted in the recess 60a. On the other hand, a cylindrical protrusion 30 b is provided on the lower surface of the second gear 30. Then, the convex portion 30 b of the second gear 30 is fitted to the inner peripheral surface of the bearing 61. Alternatively, a non-magnetic rotating shaft is provided at the center of rotation of the second gear 30, that is, at the center of the second magnet 30 a, and this rotating shaft is fitted to a bearing (for example, a bearing) provided on the base 60. May be. The third gear 40 is also rotatably supported on the base 60 in the manner described above.

A printed circuit board 70 on which a wiring pattern (not shown) is formed is attached to the base 60 by, for example, screwing so as to form a predetermined gap between the second gear 30 and the third gear 40. Has been. In other words, the printed circuit board 70 is provided so as to be rotatable about the axis of the second rotating shaft 130 with respect to the flat cable cover 50 fixed to the housing 110.
As shown in FIGS. 1 and 2, the printed circuit board 70 is on the outer side of the outer peripheral surface of the first magnet 10 in the radial direction of the first rotating shaft 120 and in the axial direction of the first rotating shaft 120. The first magnetic detection element 71 is mounted so as to be within the region where the first magnet 10 is provided. The first magnetic detection element 71 according to the present embodiment can be exemplified as an MR sensor (magnetoresistive element) that is a magnetic sensor utilizing a change in resistance value due to a magnetic field. The first magnetic detection element 71 includes a relative angle detection unit that detects a relative angle between the first rotary shaft 120 and the second rotary shaft 130 based on the magnetic field generated from the first magnet 10. Constitute. The first magnetic detection element 71 and the relative angle detection method will be described in detail later.

  In addition, a second magnetic detection element 72 is mounted on the printed circuit board 70 so as to form a predetermined gap with the second magnet 30a at a position facing the central portion of the second magnet 30a. Yes. Further, a third magnetic detection element 73 is mounted on the printed circuit board 70 so as to form a predetermined gap with the third magnet 40a at a position facing the central portion of the third magnet 40a. Yes. It can be exemplified that the second and third magnetic detection elements 72 and 73 according to the present embodiment are also MR sensors (magnetoresistive elements). The second and third magnetic detection elements 72 and 73 detect the rotation angle of the second rotating shaft 130 based on the rotation angle of the second gear 30 and the rotation angle of the third gear 40. The rotation angle detecting means is configured. The detection method will be described in detail later.

  In addition, a connector 74 electrically connected to the wiring pattern is attached to the printed circuit board 70, and a connector (not shown) provided at one end of the flat cable 80 is connected to the connector 74. Has been. As shown in FIG. 2, the flat cable 80 is wound in a spiral shape below the base 60 and inside the flat cable cover 50. One end of the flat cable 80 is connected to a connector 74 above the base 60 through a hole formed in the base 60. Further, the other end portion of the flat cable 80 is led out from the inside of the flat cable cover 50 through a hole formed in the flat cable cover 50, and outside the flat cable cover 50, for example, the electric power steering device 100. Is connected to a connector (not shown) provided on a printed circuit board (control board) of a control device (not shown) that performs the above control.

  In addition, the detection device 1 includes a relative angle calculation unit (not shown) that calculates a relative angle between the first rotation shaft 120 and the second rotation shaft 130 based on the detection value of the first magnetic detection element 71. Rotation angle calculation means (not shown) that calculates the rotation angle of the second rotation shaft 130 based on the detection values of the second and third magnetic detection elements 72 and 73 is provided. The relative angle calculation means constitutes the above-mentioned relative angle detection means, and the rotation angle calculation means constitutes the above-mentioned rotation angle detection means. These calculation means may be mounted on a printed circuit board provided outside the flat cable cover 50 separately from the printed circuit board 70 (for example, a circuit board provided in the control device described above), or mounted on the printed circuit board 70. May be.

  When the calculation means is mounted on a printed circuit board different from the printed circuit board 70, the detection values of the first to third magnetic detection elements 71 to 73 are output to the calculation means via the flat cable 80. To. Further, when the calculation means is mounted on the printed circuit board 70, the calculation means calculates the relative angle or the rotation angle based on the detection values of the first to third magnetic detection elements 71 to 73, and then calculates the calculation. The result is output to the control device via the flat cable 80.

Below, the 1st-3rd magnetic detection elements 71-73 which concern on this Embodiment are demonstrated.
The first to third magnetic detection elements 71 to 73 according to the present embodiment are MR sensors (magnetoresistive elements) using the fact that the resistance value changes due to a magnetic field.

First, the operation principle of the MR sensor will be described.
The MR sensor is composed of an Si or glass substrate and a thin film of an alloy mainly composed of a ferromagnetic metal such as Ni-Fe formed thereon, and the resistance value of the thin film ferromagnetic metal is in a specific direction. The resistance value changes according to the strength of the magnetic field.

FIG. 3 is a diagram showing the direction of the current flowing through the thin film ferromagnetic metal and the direction of the applied magnetic field. FIG. 4 is a diagram showing the relationship between the magnetic field strength and the resistance value of the thin film ferromagnetic metal when the magnetic field strength is changed in the state of FIG.
As shown in FIG. 3, a current is passed through the thin film ferromagnetic metal formed in a rectangular shape on the substrate in the longitudinal direction of the rectangle, that is, in the Y direction in the figure. On the other hand, the magnetic field H is applied in a direction perpendicular to the current direction (Y direction) (X direction in the figure), and in this state, the strength of the magnetic field is changed. FIG. 4 shows how the resistance value of the thin film ferromagnetic metal changes at this time.

As shown in FIG. 4, even if the strength of the magnetic field is changed, the resistance value change from the time of no magnetic field (magnetic field strength zero) is about 3% at the maximum.
Hereinafter, a region outside which the resistance value change amount (ΔR) can be approximately expressed by the equation “ΔR∝H ² ” is referred to as a “saturation sensitivity region”. In the saturation sensitivity region, the resistance value change of 3% does not change when the magnetic field intensity is higher than a certain magnetic field intensity (hereinafter referred to as “specified magnetic field intensity”).

FIG. 5 is a diagram showing the direction of the current flowing through the thin film ferromagnetic metal and the direction of the applied magnetic field. FIG. 6 is a diagram showing the relationship between the direction of the magnetic field and the resistance value of the thin film ferromagnetic metal.
As shown in FIG. 5, a current is passed in the rectangular longitudinal direction of the thin film ferromagnetic metal formed in a rectangular shape, that is, the Y direction in the figure, and an angle change θ is given to the current direction as the direction of the magnetic field. At this time, in order to know the change in the resistance value of the thin film ferromagnetic metal due to the direction of the magnetic field, the applied magnetic field strength is set to be equal to or higher than the above-mentioned prescribed magnetic field strength at which the resistance value does not change due to the magnetic field strength.

As shown in FIG. 6A, the amount of resistance change becomes maximum when the current direction and the magnetic field direction are perpendicular (θ = 90 °, 270 °), and the current direction and the magnetic field direction are parallel (θ = 0 °). , 180 degrees). When the maximum amount of change in the resistance value in this case is ΔR, the resistance value R of the thin film ferromagnetic metal changes as an angular component in the current direction and the magnetic field direction, and is expressed by the equation (1), and is shown in FIG. As shown in b).
R = R0−ΔRsin ² θ (1)
Here, R0 is a resistance value when a magnetic field having a specified magnetic field strength or more is applied parallel to the current direction (θ = 0 degree or 180 degrees).
From equation (1), the direction of the magnetic field greater than the prescribed magnetic field strength can be detected by grasping the resistance value of the thin film ferromagnetic metal.

Next, the detection principle of the MR sensor will be described.
FIG. 7 is a diagram illustrating an example of an MR sensor that uses the principle of detecting the direction of a magnetic field with a magnetic field strength equal to or greater than a specified magnetic field strength.
In the thin film ferromagnetic metal of the MR sensor shown in FIG. 7, a first element E1 formed so as to be elongated in the vertical direction and a second element E2 formed so as to be elongated in the horizontal direction are arranged in series. ing.

In the thin-film ferromagnetic metal having such a shape, the vertical magnetic field that causes the largest resistance value change with respect to the first element E1 is the magnetic field direction with the smallest resistance value change with respect to the second element E2. The resistance value R1 of the first element E1 is given by the formula (2), and the resistance value R2 of the second element E2 is given by the formula (3).
R1 = R0−ΔRsin ² θ (2)
R2 = R0−ΔRcos ² θ (3)

FIG. 8 is a diagram showing an equivalent circuit of the configuration of the MR sensor shown in FIG.
An equivalent circuit of the MR sensor having the element configuration as shown in FIG. 7 is as shown in FIG.
As shown in FIGS. 7 and 8, the end of the first element E1 that is not connected to the second element E2 is the ground (Gnd), and the first element E1 of the second element E2 When the output voltage at the end that is not connected is Vcc, the output voltage Vout at the connection between the first element E1 and the second element E2 is given by equation (4).
Vout = (R1 / (R1 + R2)) × Vcc (4)

When formulas (2) and (3) are substituted into formula (4) and rearranged, formula (5) is obtained.
Vout = Vcc / 2 + α × cos 2θ (5)
Here, α is α = (ΔR / (2 (2 × R0−ΔR))) × Vcc.
From equation (5), the direction of the magnetic field can be grasped by detecting Vout.

The change of the magnetic field direction when the magnet moves and the output of the MR sensor will be described.
FIG. 9 is a diagram showing the relationship between the change in the magnetic field direction and the output of the MR sensor when the magnet rotates.
As shown in FIG. 9 (a), the MR sensor shown in FIG. 7 is opposed to one surface in the direction of the central axis of a cylindrical magnet composed of a semi-cylindrical N pole and a semi-cylindrical S pole. To place. At this time, the gap L between the magnet and the MR sensor shown in FIG. 9B is a distance at which a magnetic field strength equal to or higher than the prescribed magnetic field strength is applied to the MR sensor.

Then, as shown in FIG. 9C, the magnet is rotated in the order of (i) → (ii) → (iii) → (iv) → (i) around the central axis. In such a case, a magnetic flux line is emitted from the N pole to the S pole in the magnet, and this magnetic flux line is in the direction of the magnetic field. Therefore, the MR sensor is shown in FIG. 9C according to the direction of the magnet. A magnetic field in the direction of the arrow is applied. That is, when the magnet rotates once, the direction of the magnetic field rotates once on the sensor surface.
In this case, the waveform of the output voltage Vout at the connection portion between the first element E1 and the second element E2 is “Vout = Vcc / 2 + α × cos 2θ” shown in the equation (5), which is shown in FIG. As shown, it has a two-cycle waveform.

FIG. 10 is a diagram showing the relationship between the change in the magnetic field direction and the output of the MR sensor when the magnet moves linearly.
As shown in FIG. 10 (a), the MR sensor shown in FIG. 7 is applied to a magnet in which N poles and S poles are alternately arranged. It is arranged so that the change in the direction of the magnetic field contributes to the sensor surface of the MR sensor.

  Then, the magnet is moved in the left direction as shown in FIG. Then, as shown in FIG. 10C, the magnet is moved λ from the center of the N pole to the center of the S pole (hereinafter also referred to as “magnetization pitch”) λ. In such a case, a magnetic field in the direction of the arrow shown in FIG. 10C is applied to the MR sensor according to the position of the magnet. When the magnet moves through the magnetization pitch λ, the magnetic field of the sensor surface is reduced. The direction rotates 1/2. Therefore, the waveform of the output voltage Vout at the connection portion between the first element E1 and the second element E2 is shown in FIG. 10D from “Vout = Vcc / 2 + α × cos 2θ” shown in the equation (5). Thus, a waveform of one cycle is obtained.

FIG. 11 is a diagram illustrating another example of the MR sensor.
If the element configuration shown in FIG. 11A is used instead of the element configuration shown in FIG. 7, as shown in FIG. 11B, a generally known Wheatstone bridge (full bridge) can be used. Can be configured. Therefore, detection accuracy can be increased by using the MR sensor having the element configuration shown in FIG.

A method for detecting the direction of movement of the magnet will be described.
From the relationship between the direction of the magnetic field shown in FIG. 6 and the resistance value of the thin film ferromagnetic metal, and from the equation (1) “R = R0−ΔRsin ² θ”, the direction of the magnetic field can be expressed as the current when viewed in FIG. The resistance value of the thin-film ferromagnetic metal is the same whether it is rotated clockwise or counterclockwise with respect to the direction. Therefore, even if the resistance value of the thin film ferromagnetic metal can be grasped, the direction of movement of the magnet cannot be grasped.

  FIG. 12 is a diagram illustrating an example of combinations of outputs used to detect the moving direction of the magnet. As shown in FIG. 12, the direction of movement of the magnet can be detected by combining two outputs having a phase difference of ¼ period. In order to obtain these outputs, two MR sensors may be arranged at the positions (i) and (ii) or (i) and (iv) shown in FIG.

FIG. 13 is a diagram illustrating an example of the arrangement of MR sensors. As shown in FIG. 13, it is also preferable that two MR sensors are overlapped and one sensor is disposed with an inclination of 45 degrees with respect to the other sensor.
FIG. 14 is a diagram illustrating another example of the MR sensor. As shown in FIG. 14 (a), two sets of full-bridge elements are inclined on each other by 45 degrees and formed on a single substrate to form an element structure that becomes an equivalent circuit as shown in FIG. 14 (b). Is also suitable. Thereby, as shown in FIG.14 (c), the output of an exact sine wave and a cosine wave is attained with one MR sensor. Therefore, the movement direction and the amount of movement of the magnet with respect to the MR sensor can be grasped from the output value of the MR sensor having the element configuration shown in FIG.

In view of the characteristics of the MR sensor described above, in the detection apparatus 1 according to the present embodiment, the MR sensors described below are used as the first to third magnetic detection elements 71 to 73.
First, an MR sensor having an element configuration shown in FIG. 14 is used as the first magnetic detection element 71. As described above, the first magnetic detection element 71 is disposed perpendicular to the outer peripheral surface of the first magnet 10, and the axial position of the second rotating shaft 130 is the region of the first magnet 10. Is within. Therefore, in such a case, depending on the position of the first magnet 10 due to the magnetic field generated from the first magnet 10 rotating with the first rotating shaft 120, The magnetic field direction changes as shown in FIG.

As a result, when the first magnet 10 moves (rotates) the magnetization pitch λ, the direction of the magnetic field is rotated by 1/2 on the sensor surface, and the quarter period as shown in FIG. The output results are a sine wave and a cosine wave that are phase differences.
Therefore, based on the above matters, a table of the relationship between the detection value of the first magnetic detection element 71, the relative angle between the first rotating shaft 120 and the second rotating shaft 130, and the twist direction of both is prepared in advance. It is created as a torque table and stored in, for example, a storage area of the calculation means. Then, the calculation means calculates the relative angle between the first rotating shaft 120 and the second rotating shaft 130 and the twist direction of both based on the value detected by the first magnetic detection element 71 and the torque table. Keep it available.

  Further, as the second magnetic detection element 72 and the third magnetic detection element 73, MR sensors having the element configuration shown in FIG. Then, the second magnetic detection element 72 is arranged so that the element and the upper surface of the columnar second magnet 30a face each other. The third magnetic detection element 73 is arranged so that the element and the upper surface of the columnar third magnet 40a face each other.

In such a case, the magnetic field directions with respect to the second and third magnetic detection elements 72 and 73 as shown in FIG. 9C are obtained, and the relationship between the output waveform of VoutA and the magnetic field direction is as shown in FIG. Waveform. Therefore, the rotation angles of the second and third gears 30 and 40 can be grasped from the detection values of the second and third magnetic detection elements 72 and 73.
Further, in consideration of the relationship between the number of teeth of the first gear 20 and the number of teeth of the second gear 30, the relationship between the number of teeth of the first gear 20 and the number of teeth of the third gear 40, the second In consideration of the difference between the number of teeth of the third gear 30 and the number of teeth of the third gear 40, the rotation angle of the second rotating shaft 130 and the second and third gears 30, 40 as shown in FIG. The figure which shows the relationship with the rotation angle of can be obtained.

  Therefore, based on the above matters, a table of the relationship between the detection values of the second and third magnetic detection elements 72 and 73 and the rotation angle of the second rotation shaft 130 is created in advance as a rotation angle table. For example, it is stored in a storage area of the calculation means. Then, based on the values detected by the second and third magnetic detection elements 72 and 73 and the rotation angle table, the calculation means can calculate the rotation angle of the second rotation shaft 130.

The detection apparatus 1 configured as described above functions as follows.
That is, when the user rotates the steering wheel, the first rotating shaft 120 rotates with the rotation of the steering wheel, and the torsion bar 140 is twisted. Then, the second rotating shaft 130 rotates with a slight delay from the first rotating shaft 120. This delay appears as a difference in rotation angle between the first rotating shaft 120 and the second rotating shaft 130 connected to the torsion bar 140.
When the calculation means calculates the difference in rotation angle based on the output signal of the first magnetic detection element 71 and the torque table, the detection apparatus 1 has the first rotation shaft 120 and the second rotation shaft. The relative angle with respect to 130 and the twist direction, that is, the magnitude and direction of the torque applied to the steering wheel can be detected.

Further, when the second rotating shaft 130 rotates as the steering wheel rotates, the second gear 30 and the third gear 40 that mesh with the first gear 20 become the axis of the second rotating shaft 130. Rotating around the center of rotation. In conjunction with these rotations, the second magnet 30a and the third magnet 40a also rotate. The second and third magnetism detection elements 72 and 73 detect the rotation of the second and third magnets 30a and 40a.
Then, the calculation means calculates based on the output signals of the second and third magnetic detection elements 72 and 73 and the rotation angle table, so that the detection apparatus 1 can rotate the rotation angle of the second rotation shaft 130, that is, Can detect the rotation angle (steering angle) of the steering wheel.

Further, when the detection apparatus 1 configured as described above is assembled, the flat cable cover 50, the base 60 to which the printed circuit board 70 is attached, and the flat cable 80 accommodated between the flat cable cover 50 and the base 60. Are previously unitized. Then, the unit is attached to the second housing 112 in which the second rotating shaft 130 is assembled so that the convex portion 50 a of the flat cable cover 50 fits into the concave portion 112 a of the second housing 112. At that time, the base 60 is connected to the second rotating shaft 130.
As described above, the assembling property can be improved by making the detection apparatus 1 a structure that can be unitized in advance.

In addition, the first gear 20 is provided inside the flat cable cover 50, and the second and third gears 30 and 40 that rotate and revolve while meshing with the first gear 20 are provided inside the flat cable cover 50. ing. Then, the rotation angle of the second rotation shaft 130 is detected by detecting the rotation angle of the second and third gears 30 and 40. Further, the relative angle between the first rotating shaft 120 and the second rotating shaft 130 is detected based on the output value of the first magnetic detection element 71 disposed inside the flat cable cover 50. Thereby, downsizing of the detection apparatus 1 is realized.
Further, since the relative angle between the first rotating shaft 120 and the second rotating shaft 130 is detected based on the output value of only the first magnetic detection element 71, the detection is based on the output values of a plurality of sensors. Increases the detection accuracy.

  FIG. 15 shows the rotation angles of the second and third gears 30 and 40 corresponding to the rotation angle of the second rotation shaft 130 of 1440 degrees (= 360 degrees × 4). In such a case, when the rotation angle of the second rotation shaft 130 is 720 degrees, the steering wheel is set to 0 degrees as a reference, so that the rotation of the second rotation axis is 2 rotations (720 degrees) clockwise and 2 rotations (720 degrees). The steering angle can be detected.

  Further, the number of teeth of the second and third gears 30 and 40 according to the present embodiment is made different, and the relationship between the number of teeth is shown in FIG. The number of teeth is such that the rotational position of both gears does not return to 0 degrees even when rotated. Thus, it is possible to uniquely grasp the rotation angle of the second rotation shaft 130 by grasping the rotation angles of the second gear 30 and the third gear 40.

  Then, as the number of teeth of the second and third gears 30 and 40, the number of teeth that does not return to 0 degrees even if the second rotating shaft 130 rotates N degrees is selected. It is possible to grasp the steering angle for (N / 360) rotations.

  In the above-described embodiment, the first magnetic detection element 71 is an MR sensor in which two pairs of full-bridge elements shown in FIG. 14 are inclined on each other by 45 degrees and formed on one substrate. Based on the value, the direction in which the relative angle and the angle difference between the first rotating shaft 120 and the second rotating shaft 130 are generated, in other words, the twisting direction of the torsion bar 140 is also detected.

  However, the twist direction of the first rotating shaft 120 and the second rotating shaft 130 may be detected based on the output values of the second and third magnetic detection elements 72 and 73. In such a case, the first magnetic detection element 71 only needs to detect the relative angle between the first rotation shaft 120 and the second rotation shaft 130. As the first magnetic detection element 71, FIG. An MR sensor having the element configuration shown may be used.

  In the detection device 1 described above, for example, the first magnet 10 is fixed to the first rotating shaft 120 to which the steering wheel is connected, and the base 60 is fixed to the second rotating shaft 130 on which the pinion 131 is formed. However, it is not particularly limited to such an embodiment. The first magnet 10 may be fixed to the second rotating shaft 130 on which the pinion 131 is formed, and the base 60 may be fixed to the first rotating shaft 120 to which the steering wheel is connected. Even in such a configuration, the relative angle between the first rotating shaft 120 and the second rotating shaft 130 can be detected, and the rotating angle of the first rotating shaft 120 can be detected.

The first magnet 10 is only required to be magnetized on the outer peripheral surface so that N poles and S poles are alternately arranged in the circumferential direction, and a magnet support member fixed to the first rotating shaft 120. It may be fixed to the first rotating shaft 120 via
Moreover, the 1st magnet 10 does not need to be a donut shape, and does not need to extend over the perimeter in the circumferential direction of an outer peripheral surface. The first magnet 10 only needs to be provided over a range in which the first magnetic detection element 71 can detect a change in the magnetic field at least in a range where the torsion bar 140 is twisted.

  In the above-described embodiment, the rotation angle of the second rotation shaft 130 is detected by detecting the rotation angles of the second gear 30 and the third gear 40 that are both meshed with the first gear 20. However, the second and third gears 30 and 40 are rotated by the first gear 20 while revolving around the axis of the second rotating shaft 130 as the second rotating shaft 130 rotates. If a rotational force is applied and the motor rotates, the first gear 20 may not be engaged.

FIG. 16 is a diagram illustrating another example of meshing of the first, second, and third gears 20, 30, and 40.
In the above-described embodiment, the second gear 30 and the third gear 40 are engaged with the first gear 20 and are given a rotational force by the first gear 20. For example, FIG. As shown in a), the third gear 40 is indirectly rotated by the first gear 20 via the second gear 30 by meshing with the second gear 30 that meshes with the first gear 20. May be given. Further, as shown in FIG. 16B, the second gear 30 and the third gear 40 are both engaged with the fourth gear 400 that is engaged with the first gear 20, whereby the second gear 30 and the second gear 30 are engaged. The third gear 40 may be indirectly given a rotational force by the first gear 20 via the fourth gear 400. 16C, the second gear 30 meshes with the fourth gear 400 that meshes with the first gear 20, and the third gear 40 meshes with the second gear 30. The second gear 30 and the third gear 40 may be indirectly applied with a rotational force by the first gear 20 via the fourth gear 400. Although not shown, the second gear 30 meshes with the first gear 20, the fourth gear 400 meshes with the second gear 30, and the third gear 40 meshes with the fourth gear 400. Thus, the second gear 30 is directly given rotational force by the first gear 20, and the third gear 40 is indirectly given rotational force by the first gear 20 via the fourth gear 400. May be.

Even in these cases, the rotation angles of the second and third gears 30 and 40 using the second and third magnetic detection elements 72 and 73 facing the second and third gears 30 and 40, respectively. By detecting the rotation angle, the rotation angle of the second rotation shaft 130 can be detected, and the number of teeth of the second and third gears 30 and 40 and the degree of freedom in layout selection can be increased.
In addition to the second and third gears 30 and 40, the fourth magnetic detection element for detecting the rotation angle of the fourth gear 400 shown in FIGS. It is preferable to detect the rotation angle of the second rotation shaft 130 in consideration of the rotation angle of the gear 400. By detecting the rotation angle of the second rotation shaft 130 based on the rotation angles of a large number of gears, the rotation angle of the second rotation shaft 130 that is uniquely determined by the combination of the rotation angles of the plurality of gears is more extensive. It reaches. Therefore, by detecting the rotation angle of the second rotation shaft 130 in consideration of the rotation angle of the fourth gear 400, the rotation angle of the second rotation shaft 130 can be detected in a wider range. It becomes.

In the embodiment described above, the printed circuit board 70 is rotatably arranged with respect to the housing 110 fixed to the vehicle body frame, and the first to third magnets are provided from the printed circuit board 70 via the flat cable 80. The detection values of the detection elements 71 to 73 or the results calculated based on these detection values are transmitted to the control device fixed to the main body frame.
On the other hand, a horn, an airbag, an audio control switch, and the like are disposed on the steering wheel to which the first rotating shaft 120 is coupled. The components disposed on these steering wheels need to maintain an electrical connection with the vehicle body that does not rotate even when the steering wheel is rotated.

  Therefore, the printed circuit board 70 is provided with a second connector in addition to the connector 74, and the components disposed on the steering wheel and the printed circuit board 70 are electrically connected via the second connector, a flat cable, or the like. . In addition, the components arranged on the steering wheel and the vehicle body side (control device) are electrically connected via the flat cable 80. By doing in this way, the number of parts can be reduced and the periphery of the steering wheel can be made compact, compared with the case where the parts arranged on the detection device 1 and the steering wheel are separately electrically connected to the vehicle body side.

  In the detection apparatus 1 according to the present embodiment, the rotation angle of the second rotation shaft 130 can be detected, and the relative angle between the first rotation shaft 120 and the second rotation shaft 130 can be detected. Therefore, the rotation angle of the first rotation shaft 120 is also obtained by adding the relative angle between the first rotation shaft 120 and the second rotation shaft 130 to the detected rotation angle of the second rotation shaft 130. Can be detected.

It is sectional drawing of the electric power steering device to which the detection apparatus which concerns on embodiment is applied. It is a perspective view of the detection apparatus which concerns on embodiment. It is a figure which shows the direction of the electric current sent through a thin film ferromagnetic metal, and the direction of the magnetic field to apply. It is a figure which shows the relationship between a magnetic field strength and the resistance value of a thin film ferromagnetic metal at the time of changing a magnetic field strength in the state of FIG. It is a figure which shows the direction of the electric current sent through a thin film ferromagnetic metal, and the direction of the magnetic field to apply. It is a figure which shows the relationship between the direction of a magnetic field, and the resistance value of a thin film ferromagnetic metal. It is a figure which shows an example of MR sensor using the principle which detects the direction of a magnetic field with the magnetic field intensity more than a regular magnetic field intensity. It is the figure which showed the structure of MR sensor shown in FIG. 7 with the equivalent circuit. It is a figure which shows the relationship between the change of the magnetic field direction when a magnet rotates, and the output of MR sensor. It is a figure which shows the relationship between the change of the magnetic field direction when a magnet carries out a linear motion, and the output of MR sensor. It is a figure which shows the other example of MR sensor. It is a figure which shows an example of the combination of the output used in detecting the moving direction of a magnet. It is a figure which shows the example of arrangement | positioning of MR sensor. It is a figure which shows the other example of MR sensor. It is a figure which shows the relationship between the rotation angle of a 2nd rotating shaft, and the rotation angle of the 2nd, 3rd gearwheel. It is a figure which shows the other example of meshing of a 1st, 2nd, 3rd gearwheel.

DESCRIPTION OF SYMBOLS 1 ... Detection apparatus, 10 ... 1st magnet, 20 ... 1st gearwheel, 30 ... 2nd gearwheel, 40 ... 3rd gearwheel, 50 ... Flat cable cover, 60 ... Base, 70 ... Printed circuit board, 71 ... 1st magnetic detection element, 72 ... 2nd magnetic detection element, 73 ... 3rd magnetic detection element, 80 ... Flat cable, 100 ... Electric power steering device, 110 ... Housing, 120 ... 1st rotating shaft, 130 ... Second rotating shaft, 140 ... Torsion bar, 150 ... Worm wheel, 160 ... Electric motor

Claims (9)

A detection device that detects a relative angle between a first rotation shaft that is rotatably supported by the housing and a second rotation shaft that is rotatably supported by the housing, and detects a rotation angle of the second rotation shaft. Because
A first magnet provided on the first rotating shaft;
A first gear fixed to the housing;
A second gear that rotates with the rotational force applied by the first gear while revolving around the axis of the second rotation shaft as the rotation center of the second rotation shaft;
Along with the rotation of the second rotation shaft, a rotation force is applied by the first gear while revolving around the axis of the second rotation shaft, and the number of teeth of the second gear is rotated. A third gear having a different number of teeth than
A relative angle detector that is fixed to the second rotating shaft and detects a relative angle between the first rotating shaft and the second rotating shaft based on a magnetic field generated from the first magnet;
A rotation angle detecting means for detecting a rotation angle of the second rotation shaft based on the rotation angle of the second gear and the rotation angle of the third gear;
A detection apparatus comprising: The first magnet has N poles and S poles alternately arranged on the outer peripheral surface,
The relative angle detecting means includes a first magnetoresistive element that is disposed outside the outer peripheral surface of the first magnet and has a magnetic body that extends perpendicularly to the axis of the first rotating shaft. The detection device according to claim 1, wherein A second magnet that rotates with the second gear; and a third magnet that rotates with the third gear;
The rotation angle detecting means is configured to detect a rotation angle of the second gear based on a magnetic field generated from the second magnet, and a magnetic field generated from the third magnet. A third magnetoresistive element that detects the rotation angle of the third gear based on the second magnetoresistive element, and the second magnetoresistive element and the value detected by the third magnetoresistive element The detection device according to claim 2, wherein the rotation angle of the second rotation shaft is detected.   The detection apparatus according to claim 3, wherein the first magnetoresistive element, the second magnetoresistive element, and the third magnetoresistive element are mounted on the same printed circuit board. .   5. The apparatus according to claim 1, further comprising a support member that rotatably supports at least one of the second gear and the third gear and is fixed to the second rotating shaft. The detection apparatus according to item 1. A support member that rotatably supports at least one of the second gear and the third gear and that is fixed to the second rotation shaft;
The detection device according to claim 4, wherein the printed circuit board is fixed to the support member. The second gear meshes with the first gear and rotates,
The detection device according to claim 1, wherein the third gear meshes with the first gear or the second gear and rotates. A detection device that detects a relative angle between a first rotation shaft that is rotatably supported by the housing and a second rotation shaft that is rotatably supported by the housing, and detects a rotation angle of the second rotation shaft. Because
A first gear fixed to the housing;
A second gear that rotates with the rotational force applied by the first gear while revolving around the axis of the second rotation shaft as the rotation center of the second rotation shaft;
Along with the rotation of the second rotation shaft, a rotation force is applied by the first gear while revolving around the axis of the second rotation shaft, and the number of teeth of the second gear is rotated. A third gear having a different number of teeth than
A relative angle between the first rotating shaft and the second rotating shaft is detected based on a magnetic field generated by a first magnet fixed to the second rotating shaft and provided on the first rotating shaft. Relative angle detection means for
A rotation angle detecting means for detecting a rotation angle of the second rotation shaft based on the rotation angle of the second gear and the rotation angle of the third gear;
A detection apparatus comprising: A first rotating shaft rotatably supported by the housing and coupled to the steering wheel;
A second rotating shaft supported rotatably on the housing and connected to the first rotating shaft via a torsion bar;
A first magnet provided on the first rotating shaft;
A first gear fixed to the housing;
A second gear that rotates with the rotational force applied by the first gear while revolving around the axis of the second rotation shaft as the rotation center of the second rotation shaft;
Along with the rotation of the second rotation shaft, a rotation force is applied by the first gear while revolving around the axis of the second rotation shaft, and the number of teeth of the second gear is rotated. A third gear having a different number of teeth than
A relative angle detector that is fixed to the second rotating shaft and detects a relative angle between the first rotating shaft and the second rotating shaft based on a magnetic field generated from the first magnet;
A rotation angle detecting means for detecting a rotation angle of the second rotation shaft based on the rotation angle of the second gear and the rotation angle of the third gear;
A power steering apparatus comprising:

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