JP2011209196A - Torque index sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a compact torque index sensor having functions of both a torque sensor and an index sensor and composed of a reduced number of parts.SOLUTION: The torque index sensor includes: a torque detection section 4 for detecting torque received by a rotary shaft 2 rotated by steering operation by an even number of magnetic detection elements 3a and 3b; and a rotation reference position detection section 5 for detecting a rotation reference position of the rotary shaft 2 by the magnetic detection elements 3a and 3b of the torque detection section 4. The rotation reference position detection section 5 includes: a collar 7 which is rotated with the rotary shaft 2 and around which a guide groove 6 is formed; and a magnet for index 8 which approaches and separates from the magnetic detection elements 3a and 3b by guidance of the guide groove 6 with the rotation of the collar 7.

Description

  The present invention relates to a compact torque index sensor having both functions of a torque sensor and an index sensor.

  An electric power steering device for a vehicle includes a steering wheel for a driver to perform a steering operation, an input shaft rotated by the steering wheel, a connecting shaft (torsion torque) to which torque (steering torque) is applied by rotation of the input shaft, An output assisting motor rotated by torque applied to the connecting shaft and an operation assisting motor driven in accordance with the torque applied to the connecting shaft, the steering assisting mechanism connected to the output shaft being operated by the assisting motor. By transmitting this driving force, the driver's steering operation is assisted.

  In the electric power steering apparatus, in order to control the driving of the operation assisting motor, it is necessary to detect the torque applied to the connecting shaft.

  Conventionally, with respect to a torque sensor, as described in Patent Document 1, a substantially cylindrical cylindrical magnetic part made of a hard magnetic material provided on an input shaft and a magnetic sensor provided on an output shaft are arranged in a magnetic field of the cylindrical magnetic part. A pair of ring-shaped ring magnetic parts (magnetic yokes) made of a soft magnetic material forming a magnetic circuit, and a pair of ring-shaped magnets that magnetically couple with the ring magnetic part and induce magnetic flux from the ring magnetic part. A magnetism collecting ring, a magnetism detecting element for detecting a magnetic flux induced by the magnetism collecting ring, and a calculation unit, in which the output of the magnetism detecting element and the torsional elasticity (torque-torsion angle characteristics) of the connecting shaft are provided. Based on this, there is known one that calculates a torque applied to a connecting shaft.

  Further, in the electric power steering apparatus, it is necessary to detect the steering wheel direction (steering angle) that changes along with the steering operation together with the steering torque.

  Conventionally, with respect to the steering angle sensor, as described in Patent Document 2, a pair of gears having different numbers of teeth that rotate in conjunction with the rotation of the output shaft around two shafts positioned parallel to the output shaft, And a plurality of magnetic detection elements for detecting the rotation angle of each gear, and a steering angle sensor for detecting a steering angle based on a combination of the respective rotation angles detected by each magnetic detection element is known. Yes. A steering angle sensor like this Patent Document 2 is called a mechanical steering angle sensor.

  In addition to the mechanical steering angle sensor as in Patent Document 2, as a new method, the output position is determined by setting the reference position to the rotation position of the output shaft and detecting (indexing) that the output shaft is at the rotation reference position. There is an index type steering angle sensor that detects the number of rotations of a shaft and uses it to detect a steering angle. For example, the electric power steering apparatus is provided with an operation assisting motor, and the relative angle of the output shaft can be obtained based on the rotation angle of the operation assisting motor. Steering by obtaining the absolute angle of the output shaft based on the relative angle of the output shaft obtained from the auxiliary motor and the rotation speed of the output shaft detected by detecting that the output shaft is at the rotation reference position Corner detection can be performed.

JP 2003-149062 A JP 2007-269281 A

  The present inventors paid attention to the technology of the index-type steering angle sensor, and considered to add a torque sensor and an index sensor for the index-type steering angle sensor to the electric power steering apparatus.

  However, if the torque sensor and the index sensor are simply provided, only two sensors are provided, and there is a problem that not only the number of parts is increased, but also the size is not reduced.

  Accordingly, an object of the present invention is to provide a torque index sensor that solves the above-described problems and has both functions of a torque sensor and an index sensor and can contribute to reduction in the number of parts and downsizing.

  In order to achieve the above object, the present invention provides a torque detector that detects the torque received by a rotating shaft that is rotated by a steering operation by an even number of magnetic detecting elements, and the magnetic detecting element of the torque detecting unit. A rotation reference position detection unit that detects a rotation reference position, the rotation reference position detection unit being rotated along with the rotation shaft, and a collar having a guide groove formed around the rotation reference position. Accordingly, an indexing magnet guided by the guide groove and approaching / separating only once from the magnetic detection element is provided.

  The guide groove is made to approach a flat portion that holds the index magnet at a position far from the magnetic detection element, and an approach inclination portion that causes the index magnet to approach the magnetic detection element from the far position. The indexing magnet may further include a separation inclined portion that separates the index magnet from the magnetic detection element to the far position.

  The present invention exhibits the following excellent effects.

  (1) Since the functions of the torque sensor and the index sensor are combined using a common member, a compact torque index sensor can be proposed with a small number of parts.

It is a sectional side view in the rotation reference position of the torque index sensor which shows one Embodiment of this invention. FIG. 2 is an enlarged front view of the vicinity of a magnetic detection element as viewed from an arrow A in FIG. 1. (A) is a side view of the collar, (b) is a side view and top view of the movable piece, and (c) is a side view and top view of the thrust guide. It is a sectional side view in the position rotated 90 degrees from the rotation reference position of the torque index sensor of FIG. It is a sectional side view in the position rotated 180 degrees from the rotation reference position of the torque index sensor of FIG. It is the graph which showed the change of the output voltage (voltage ratio) of the magnetic detection element in 1 rotation of a rotating shaft. It is a decomposition explanatory view of the torque detection part of the torque index sensor of the present invention. (A), (b) is an image figure for demonstrating that magnetic flux changes according to the rotational position shift of the magnet for torque detection and a detection yoke in this invention. It is an enlarged side view of the vicinity of a magnetic detection element for explaining a magnetic flux related to torque detection in the present invention. FIG. 6 is a torque versus magnetism detection output characteristic diagram showing the relationship between the torque received by the connecting shaft and the output of the magnetism detection element in the present invention. It is a rotation angle versus magnetism detection output characteristic figure showing the relation between the rotation angle of a rotating shaft and the output of a magnetic detection element in the present invention.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

  As shown in FIG. 1, a torque index sensor 1 according to the present invention includes a torque detection unit 4 that detects torque received by a rotating shaft 2 that is rotated by a steering operation by an even number of magnetic detection elements 3a and 3b, and a torque detection unit. And a rotation reference position detection unit 5 that detects a rotation reference position of the rotation shaft 2 by the magnetic detection elements 3a and 3b. The rotation reference position detection unit 5 is rotated along with the rotation shaft 2 and has a guide groove around it. 6 and the magnetic detection element 3a. And an index magnet 8 that approaches / separates only once with respect to 3b.

  Here, the rotating shaft 2 may be any of an input shaft fixed to a steering wheel of a vehicle (not shown), an output shaft connected to a tire, and a connecting shaft that connects the input shaft and the output shaft.

  The torque detector 4 is conventionally known, but the present invention has a feature in combination with the rotation reference position detector 5 and will be described in detail later. Here, only the magnetic detection elements 3a and 3b and the periphery thereof in the torque detection unit 4 will be described. That is, as members of the torque detector 4, magnetism collecting rings 9 a and 9 b are provided at both ends in the axial direction, and proximity parts 10 a and 10 b are provided at one side of the magnetism collecting rings 9 a and 9 b, respectively. The magnetism collecting rings 9a and 9b and the proximity portions 10a and 10b are for guiding the magnetic flux in the torque detection unit 4 to the magnetic detection elements 3a and 3b.

  As shown in FIG. 2, one of the magnetic detection elements 3a is arranged with the detection surface F facing one of the proximity portions 10a, and the other magnetic detection element 3b of the other magnetic detection element 3b has the detection surface F of the other proximity portion 10b. Arranged to face. The two magnetic detection elements 3a and 3b are arranged in the circumferential direction at the same position in the axial direction, but the axial position of the detection surface F is different, and the magnetic detection element 3a has the detection surface F close to the proximity portion 10a. The magnetic detection element 3b is arranged with the detection surface F close to the proximity portion 10b.

  As shown in FIG. 1, the collar 7 of the rotation reference position detection unit 5 is a cylinder coaxial with the rotation shaft 2 attached to the rotation shaft 2, and rotates as the rotation shaft 2 rotates. The collar 7 has an appropriate thickness in the axial direction. The guide groove 6 is formed on the outer peripheral surface of the collar 7 so as to return to its original shape after making a round of the collar 7 while being partially bent.

  The guide groove 6 includes a flat portion 6a for holding the index magnet 8 at a position far from the magnetic detection elements 3a and 3b, and an approach inclination for causing the index magnet 8 to approach the magnetic detection elements 3a and 3b from the far position. It has the part 6b and the separation | decrease inclination part 6c (refer FIG. 4) which makes the magnet 6 for an index approached separate to the said far position. The flat portion 6a is provided at the end of the collar 7 opposite to the magnetic detection elements 3a and 3b without being inclined with respect to the axis. The approaching inclined portion 6b is provided to be inclined with respect to the axis from the boundary connected to the flat portion 6a to the end of the collar 7 on the side of the magnetic detection elements 3a and 3b. The separating inclined portion 6c is provided so as to be inclined from the boundary connected to the approaching inclined portion 6b to the flat portion 6a opposite to the approaching inclined portion 6b with respect to the axis. As a result, the guide groove 6 has the boundary between the approaching inclined portion 6b and the separating inclined portion 6c closest to the magnetic detection elements 3a and 3b. In the present embodiment, the position where the movable piece 11 comes to the boundary between the approaching inclined portion 6b and the separating inclined portion 6c is set as the rotation reference position.

  The rotation reference position detection unit 5 includes a movable piece 11 that can move while holding the index magnet 8 and a thrust guide 12 that restricts the movement of the movable piece 11 only in the axial direction. The movable piece 11 is provided outside the collar 7 in the radial direction so as to face the outer periphery of the collar 7. The movable piece 11 is protruded radially inward of the rotary shaft 2 and engaged with the guide groove 6, and the thrust groove formed in the thrust guide 12 is protruded radially outward of the rotary shaft 2. 13 and a second projection 11b engaged with the first projection 11b. The thrust guide 12 is provided outside the collar 7 in the radial direction and is fixed to a stationary system with a space for sandwiching the movable piece 11 from the collar 7. The thrust guide 12 is formed with a thrust guide groove 13 extending in parallel with the axis of the rotary shaft 2. The collar 7, the movable piece 11, and the thrust guide 12 are made of a nonmagnetic material.

  As shown in FIG. 3A, the guide groove 6 of the collar 7 has a flat portion 6 a, an approaching inclined portion 6 b, and a separating inclined portion 6 c, and a reference line C <b> 1 parallel to the axis of the rotating shaft 2. On the other hand, the approaching inclined portion 6b and the separating inclined portion 6c form an angle θ. Although the cross section of the guide groove 6 is not shown, the guide groove 6 has a semicircular cross section like the thrust guide groove 13.

  As shown in FIG. 3 (b), the movable piece 11 has a hemispherical first protrusion 11 a for engaging with the guide groove 6 and two hemispherical first protrusions for engaging with the thrust guide groove 13. 2 projections 11b.

  As shown in FIG. 3C, the thrust guide 12 has two thrust guide grooves 13 that are semicircular in cross section and extend parallel to the axis of the rotary shaft 2.

  As shown in FIG. 1, the movable piece 11 is sandwiched between the collar 7 and the thrust guide 12, the first protrusion 11 a is engaged with the guide groove 6, and the two second protrusions 11 b are respectively engaged with the thrust guide groove 13. By combining, three points are supported and movement in the axial direction is allowed.

  Next, the operation of the rotation reference position detection unit 5 will be described.

  As shown in FIG. 4, when the rotary shaft 2 is at a position rotated by 90 ° from the rotation reference position, the collar 7 is also rotated by 90 °, so that the flat portion 6a comes to the position of the arrow B. ing. Therefore, the movable piece 11 is guided to the flat portion 6a, and the index magnet 8 is held at a position far from the magnetic detection elements 3a and 3b.

  As shown in FIG. 5, even when the rotary shaft 2 is at a position rotated 180 ° from the rotation reference position, the collar 7 is also rotated 180 ° with the rotation, so that the flat portion 6a is located at the position of the arrow B. It is coming. Therefore, as in the case of FIG. 4, the movable piece 11 is guided to the flat portion 6a, and the index magnet 8 is held at a position far from the magnetic detection elements 3a and 3b.

  When the rotary shaft 2 rotates to near 360 ° from the state of FIG. 5, the collar 7 also rotates to near 360 °, and the approaching inclined portion 6b comes to the position of the arrow B. When the movable piece 11 is guided to the approaching inclined portion 6b, the index magnet 8 approaches the magnetic detection elements 3a and 3b. As shown in FIG. 1, when the rotary shaft 2 is rotated to the rotation reference position (360 ° = 0 °), the collar 7 is also rotated to 0 °, and the index magnet 8 is the most magnetic detecting element 3a, 3b. Get closer to. Further, when the rotary shaft 2 rotates, the collar 7 also rotates and exceeds 0 °, so that the movable piece 11 is guided to the separation inclined portion 6c, and the index magnet 8 moves away from the magnetic detection elements 3a and 3b. When the rotation direction of the rotating shaft 2 is opposite to the illustrated arrow, the separating inclination portion 6c described so far becomes the approaching inclination portion 6b, and the approaching inclination portion 6b described so far is the separation inclination portion. 6c. Therefore, in FIGS. 1 and 3 to 5, reference numerals at the time of reverse rotation are shown in parentheses.

  Thus, as the rotary shaft 2 rotates once, that is, the collar 7 rotates once, the index magnet 8 is guided to the guide groove 6 and the magnetic detection elements 3a. 3b approaches / separates only once.

  Here, when the magnetic path from the index magnet 8 to the magnetic detection elements 3a and 3b is shown in FIG. 1, the magnetic path is divided into the magnetic collecting ring 9a and the magnetic collecting ring 9b from the N pole, The magnetism collecting ring 9a reaches the magnetic detection element 3a via the proximity part 10a, and the magnetism collection ring 9b reaches the magnetic detection element 3b via the proximity part 10b. Such a magnetic path is formed in the same manner in the states of FIGS. 4 and 5, but the index magnet 8 is closest to the magnetic detection elements 3a and 3b in the state of FIG. The magnetic flux density applied to the magnetic detection elements 3a and 3b is large.

  When the change in the output voltage of the magnetic detection elements 3a and 3b with respect to the rotation angle is indicated by the voltage ratio to the output voltage at the rotation angle of 180 °, the output voltage of the magnetic detection elements 3a and 3b is rotated as shown in FIG. It becomes larger near the reference position. Here, for example, the angle θ is 30 °, and the stroke distance of the index magnet 8 (the movement distance of the index magnet 8 in the axial direction of the rotary shaft 2) is 6 mm. The steepness of the graph of FIG. 6 seems to depend on the angle θ.

  As described above, in the torque index sensor 1 of the present invention, the rotation reference position detection unit 5 is rotated along with the rotation shaft 2 and the collar 7 having the guide groove 6 formed in the periphery, and the collar 7 are provided. As it is rotated once, it is guided by the guide groove 6 and magnetic detection elements 3a. Since the index magnet 8 that approaches / separates only once with respect to 3b is provided, the rotation reference position can be detected from the output voltages of the magnetic detection elements 3a and 3b.

  The rotation reference position detection unit 5 is easy to process because the collar 7, the movable piece 11, and the thrust guide 12 are made of, for example, a nonmagnetic material such as resin. For this reason, the guide groove 6 that determines the relative position between the magnetic detection elements 3a and 3b and the index magnet 8 can be easily adjusted to a precise and arbitrary shape.

  The rotation reference position detection unit 5 includes a collar 7 provided with a guide groove 6 around the periphery and a thrust guide 12 provided with a thrust guide groove 13 parallel to the axis of the rotary shaft 2. The frame 11 moves only in the axial direction. For this reason, the index magnet 8 does not move in the direction in which the magnetic detection elements 3a and 3b are arranged (the circumferential direction of the rotating shaft 2). If the magnet moves in the direction in which the magnetic detection elements 3a and 3b are arranged, a plurality of peaks may occur in the sum of the output voltages of the magnetic detection elements 3a and 3b. There is no fear.

  Next, the torque detector 4 will be described in detail.

  As shown in FIG. 7, the torque detection unit 4 includes a pair of detections that are attached to an output shaft (not shown) and a torque detection magnet 71 that is attached to an output shaft (not shown) and surrounds the torque detection magnet 71 in a non-contact manner. The yokes 72a and 72b, the pair of magnetism collecting rings 9a and 9b surrounding each of the detection yokes 72a and 72b in a non-contact manner, and the pair of magnetism collecting rings 9a and 9b attached to the magnetism sensing elements 3a and 3b, respectively. Proximity parts 10a and 10b are provided. The input shaft and the output shaft are connected by a connecting shaft 73.

  The torque detection magnet 71 is a cylindrical magnet in which a plurality of N poles and S poles are alternately arranged at a predetermined pitch in the circumferential direction. The torque detection magnet 71 is coaxial with the input shaft and rotates integrally with the input shaft.

  The detection yokes 72a and 72b are arranged in an annular shape that surrounds the periphery of the torque detection magnet 71 in a non-contact manner with an appropriate narrow gap from the torque detection magnet 71, and the same pitch as the arrangement pitch of the same magnetic poles in the torque detection magnet 71 A plurality of claws are formed. The detection yokes 72a and 72b are disposed at different positions in the axial direction. The detection yokes 72a and 72b are coaxial with the output shaft and rotate integrally with the output shaft.

  As shown in detail in FIG. 8A, the detection yokes 72a and 72b are attached coaxially to the output shaft by shifting the isosceles triangular claws by a half pitch in the circumferential direction. The detection yokes 72a and 72b are for guiding the magnetic flux from the torque detection magnet 71 with different distributions according to the torsional deformation of the connecting shaft.

  As shown in the enlarged view in a circle of FIG. 7, one magnetic detection element 3 a is arranged with the detection surface F facing the base end direction (on the drawing), and the other magnetic detection element 3 b F is arranged facing the front end direction (lower side in the figure). The two magnetic detection elements 3a and 3b are arranged in the circumferential direction at the same position in the axial direction, but the axial positions of the detection surfaces F are different.

  Further, the detection direction of one magnetic detection element 3a is directed to the proximal end, and the detection direction of the other magnetic detection element 3b is directed to the distal end. Thus, the two magnetic detection elements 3a and 3b are provided with different detection directions (see FIG. 2).

  Next, the operation of the torque detector 4 in FIG. 7 will be described with reference to FIGS.

  As shown in FIG. 8A, in the neutral state in which the steering wheel is not steered and the connecting shaft 73 is not receiving torque, the detection yokes 72a and 72b have torque detection magnets at their tips. 71 refers to the boundary between the north and south poles. Thereby, in both the detection yoke 72a and the detection yoke 72b, the area where the claw faces the N pole of the torque detection magnet 71 is equal to the area where the claw faces the S pole, and both the detection yokes 72a and 72b are connected via the claw. Since the magnetic flux entering from the N pole and the magnetic flux exiting to the S pole are equal, no magnetic flux is generated between the detection yokes 72a and 72b.

  As shown in FIG. 8B, in a torque application state in which the steering wheel is steered and the connecting shaft 73 receives torque, the connecting shaft 73 is attached to the input shaft due to torsional deformation. The relative position in the circumferential direction of the torque detection magnet 71 and the detection yokes 72a and 72b attached to the output shaft changes. In the detection yoke 72a, the area where the claw faces the N pole is larger than the area where the claw faces the S pole. Therefore, the magnetic flux entering from the N pole through the claw is larger than the magnetic flux exiting from the S pole through the claw. In the detection yoke 72b, the area where the claw faces the N pole is smaller than the area where the claw faces the S pole. Therefore, the magnetic flux entering from the N pole through the claw is smaller than the magnetic flux exiting from the S pole through the claw. As a result, a magnetic polarity difference occurs between the detection yokes 72a and 72b, and a magnetic flux is generated between the detection yokes 72a and 72b. This magnetic flux is guided by the magnetic flux collecting rings 9a and 9b and collected in the proximity portions 10a and 10b.

  As a result, as shown in FIG. 9, a magnetic flux is generated between the two adjacent portions 10a and 10b. The magnetic flux is detected by the two magnetic detection elements 3a and 3b, respectively. At this time, the magnetic flux density between the two adjacent portions 10a and 10b during the change from the state of FIG. 8A to the state of FIG. 8B is the circumference of the torque detection magnet 71 and the detection yokes 72a and 72b. This is proportional to the displacement of the direction, that is, the torsional deformation of the connecting shaft 73. That is, the outputs of the magnetic detection elements 3 a and 3 b are proportional to the torque received by the connecting shaft 73.

10, each of the magnetic detection elements 3a for the torque connection shaft 73 is subjected, it shows a change in the output V _t of 3b. However, it is assumed that the index magnet 8 is sufficiently separated from the magnetic detection elements 3a and 3b, and there is no influence of the magnetic flux by the index magnet 8. Since the magnetic detection elements 3a and 3b output the detected magnetic flux density as a voltage, an output V _t proportional to the torque is obtained. The value of the output V _t when the connecting shaft 73 is in a neutral state not receiving torque is set to V _off . Since the detection directions of the two magnetic detection elements 3a and 3b are opposite to each other, the increase / decrease direction of the detected output is opposite. That is, assuming that the output graph of the magnetic detection element 8a whose detection direction is the proximal direction is rising to the right, the output graph of the magnetic detection element 8b whose detection direction is the distal direction is falling to the right.

  In this manner, the torque detector 4 can detect a signal representing torque.

  The torque index sensor 1 according to the present invention uses the magnetic detection elements 3a and 3b of the torque detector 4 to obtain a rotation reference position detection signal. As described above, the magnetic detection elements 3a and 3b are configured such that the direction of increase / decrease of the output is opposite to the torque. Therefore, the rotation reference position detection unit 5 makes the increase / decrease direction of the magnetic detection elements 3a and 3b the same as the rotation of the rotary shaft 2. Thereby, a signal representing torque is obtained from the difference between the outputs of the magnetic detection elements 3a and 3b, and a signal for detecting the rotation reference position is obtained from the sum of the outputs. The torque is obtained by comparing the value of a storage unit (not shown) that stores the relationship between the output difference between the magnetic detection elements 3a and 3b and the torque and the detected output difference.

  Hereinafter, the operation of the rotation reference position detection unit 5 combined with the torque detection unit 4 will be described.

  As already described, when the collar 7 rotates with the rotation of the rotary shaft 2, the index magnet 8 approaches / separates from the magnetic detection elements 3a and 3b. As a result, the magnetic detection elements 3a and 3b detect a change in magnetic flux caused by the index magnet 8.

FIG. 11 shows the relationship between the rotation angle of the output shaft 3 and the values obtained by normalizing the outputs V _i of the magnetic detection elements 3a and 3b with the maximum output V _iMax at the entire rotation angle. However, it is assumed that the torque index sensor 1 is in a neutral state in which the connecting shaft does not receive torque and is not affected by the magnetic flux from the torque detection magnet 71. In the present embodiment, when the rotary shaft 2 is far from the rotation reference position, that is, when the index magnet 8 is sufficiently separated from the magnetic detection elements 3a and 3b, in the present embodiment, the first protrusion 11a is a flat portion of the guide groove 6. The value of the output V _i when it is at 6a is V _off . When the index magnet 8 is closest to the magnetic detection elements 3a and 3b, in this embodiment, the position where the movable piece 11 comes to the boundary between the approaching inclined portion 6b and the separating inclined portion 6c is the rotation axis. When 2 is at the rotation reference position, the rotation angle at this time is expressed as 0 degree.

As shown in FIG. 11, the output V _i is maximum when the rotation angle of the rotary shaft 2 is 0 degree, rapidly decreases regardless of whether the rotation angle is positive or negative, and the rotation angle is about ± 10 degrees. V _off when V is exceeded. From this, when the output V _i reaches the maximum value or exceeds a predetermined threshold value, it can be determined that the output shaft 3 is at the rotation reference position.

  Next, an operation for simultaneously performing torque detection and rotation reference position detection will be described.

In the calculation unit (not shown), the outputs V _t related to the torque and the output V _i related to the rotation reference position are calculated by performing the calculations of the expressions (1) and (2) using the outputs of the two magnetic detection elements 3a and 3b. Can be obtained.

However, V ₁ and V ₂ are outputs of the magnetic detection elements 3a and 3b. The values of the outputs V ₁ and V ₂ when the connecting shaft is in a neutral state receiving no torque and the rotating shaft 2 is far from the rotation reference position are set as the offset value V _off .

As described above, the difference between the outputs V ₁ and V ₂ of the two magnetic detection elements 3a and 3b is taken, and the offset value V _off is subtracted from the difference, thereby obtaining the output V _t related to the torque. On the other hand, two magnetic detection elements 3a, by subtracting the offset value V _off from half the sum of the outputs V _1, V ₂ of 3b, the output V _i of the rotation reference position is obtained.

Output V _i of the rotation reference position, by the appropriate values to the threshold, it can be judged that the rotation shaft 2 is in rotation reference position. The offset value V _off does not impair information on the torque and the rotation reference position even if the value is changed as necessary.

As described above, according to the torque index sensor 1 of the present invention, the magnetic flux of the torque detecting magnet 71 and the magnetic flux of the index magnet 8 are superimposed on each other and applied to the magnetic detection elements 3a and 3b. Since the detection directions of the detection elements 3a and 3b are made different from each other, the output V _t related to the torque and the output V _i related to the rotation reference position are derived from the outputs V ₁ and V _{2 of} the magnetic detection elements 3a and 3b. A reference position can be detected. In other words, since the torque detection unit 4 and the rotation reference position detection unit 5 using the common magnetic detection elements 3a and 3b are included in one torque index sensor 1, the number of components can be reduced, and Thus, the torque index sensor 1 that can be made compact can be obtained.

DESCRIPTION OF SYMBOLS 1 Torque index sensor 2 Rotating shaft 3a, 3b Magnetic detection element 4 Torque detection part 5 Rotation reference position detection part 6 Guide groove 7 Collar 8 Index magnet 9a, 9b Magnetic collecting ring 10a, 10b Proximity part 11 Movable piece 12 Thrust guide

Claims (2)

A torque detector that detects the torque received by the rotating shaft rotated by the steering operation by an even number of magnetic detection elements;
A rotation reference position detection unit that detects a rotation reference position of the rotation shaft by the magnetic detection element of the torque detection unit;
The rotation reference position detector
A collar which is rotated along with the rotating shaft and has a guide groove formed around it;
An indexing magnet that is guided in the guide groove as the collar makes one rotation and approaches / separates only once from the magnetic detection element;
A torque index sensor comprising:   The guide groove is made to approach a flat portion that holds the index magnet at a position far from the magnetic detection element, and an approach inclination portion that causes the index magnet to approach the magnetic detection element from the far position. 2. The torque index sensor according to claim 1, further comprising a separation inclined portion that separates the index magnet from the magnetic detection element to the position far from the magnetic detection element.

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