JP5514603B2 - Torque index sensor - Google Patents

Description

  The present invention relates to a 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 field provided on an output shaft and disposed 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 a reduction in the number of parts and a reduction in size.

In order to achieve the above object, according to the present invention, an input shaft and an output shaft are connected via a connecting shaft that is torsionally deformed, and a first magnet is connected to one of the input shaft and the output shaft. A yoke is attached, and two magnetic detection elements are provided in a region sandwiched between the pair of yokes so that the detection surface and the detection direction are different from each other, and the magnetic field is placed at a predetermined position in the circumferential direction of the output shaft. A second magnet that provides another magnetic field that is superimposed on the two magnetic detection elements is detected, and the torque received by the connecting shaft is detected from the difference between the two magnetic field strengths detected by the two magnetic detection elements, and the two magnetic detection elements detect It is detected from the sum of the two magnetic field intensities that the output shaft is at the rotation reference position.

  The first magnet 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, and is attached coaxially to the input shaft or the output shaft. A plurality of claws are formed in a ring surrounding the first magnet in a non-contact manner at the same pitch as the arrangement pitch of the same magnetic pole in the first magnet, and each yoke is in the axial direction of the first magnet. The yokes may be arranged at different positions, and may be attached coaxially to the output shaft or the input shaft by shifting the claws from each other by a half pitch in the circumferential direction.

  Two outer yokes may be provided to surround each of the yokes at a distance from the yokes.

  Proximity yokes for narrowing the gap between the two outer yokes are respectively attached to predetermined positions in the circumferential direction of the two outer yokes, and the two magnetic detection elements are disposed between the two proximity yokes. Good.

  The second magnet may be disposed at an axial position corresponding to the middle of the detection surfaces of the two magnetic detection elements.

  The second magnet may be arranged at an axial position corresponding to the outside between the detection surfaces of the two magnetic detection elements.

  An auxiliary yoke for guiding the magnetic flux from the second magnet to the two magnetic detection elements may be provided.

  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, it is possible to provide a torque index sensor that can contribute to reduction in the number of parts and downsizing.

It is a sectional side view of the torque index sensor which shows one Embodiment of this invention. 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 a magnetic field changes according to the rotation position shift of a 1st magnet and a yoke in this invention. It is a principal part sectional side view for demonstrating the magnetic field which concerns on a torque detection in this invention. FIG. 6 is a torque vs. magnetic detection output characteristic diagram showing the relationship between the torque received by the connecting shaft in the present invention and the output of the magnetic detection element due to the magnetic field for torque detection. It is a principal part sectional side view for demonstrating the magnetic field which concerns on rotation reference position detection in this invention. It is a rotation angle versus magnetism detection output characteristic figure showing the relation between the rotation angle of an output shaft and the output of a magnetism detection element by the magnetic field concerning rotation reference position detection in the present invention. It is a sectional side view of the torque index sensor which shows other embodiment of this invention. It is a figure for demonstrating the magnetic field in the torque index sensor of FIG. It is principal part side sectional drawing for demonstrating the magnetic field which concerns on the torque detection in other embodiment of this invention. It is principal part sectional drawing for demonstrating the magnetic field which concerns on rotation reference position detection in other embodiment of this invention.

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

  As shown in FIG. 1, the torque index sensor 1 according to the present invention is connected to an input shaft 2 and an output shaft 3 via a connecting shaft 4 that is torsionally deformed. A pair of yokes 6 and 7 with one magnet 5 facing each other is attached, and in the region sandwiched between the pair of yokes 6 and 7, the two magnetic detection elements 8a and 8b are positioned on the detection surface and in the detection direction. The second magnet 9 is provided at a predetermined position in the circumferential direction of the output shaft 3 to give another magnetic field superimposed on the magnetic field.

  The torque index sensor 1 of the present invention has a torque detector that detects the torque received by the connecting shaft 4 based on the strength of the magnetic field detected by the magnetic detection elements 8a and 8b. That is, as shown in FIG. 2, the torque detector mainly includes a first magnet 5, a pair of yokes 6 and 7, and magnetic detection elements 8 a and 8 b.

  The torque index sensor 1 according to the present invention applies a different magnetic field to the torque detector, and determines that the output shaft 3 is at the rotation reference position based on the strength of the different magnetic fields detected by the magnetic detection elements 8a and 8b. A rotation reference position detection unit for detection is configured. However, since two superimposed magnetic fields are applied to the two magnetic detection elements 8a and 8b, the details will be described later, but in the torque index sensor 1 of the present invention, the two magnetic detection elements 8a and 8b have detected. The torque received by the connecting shaft 4 is detected from the difference between the two magnetic field strengths, and it is detected from the sum of the two magnetic field strengths detected by the two magnetic detection elements 8a and 8b that the output shaft 3 is at the rotation reference position. It has become. The torque is obtained by comparing the value of a storage unit (not shown) that stores the relationship between the difference in magnetic field strength and the torque and the detected difference in magnetic field strength.

  As shown in FIG. 1, the input shaft 2 has a coaxial cavity 2a into which the connecting shaft 4 is inserted, and is connected to a proximal end (an end close to a steering wheel not shown; an upper end in the figure) in the coaxial cavity 2a. The base end of the shaft 4 is connected by a connecting pin 10. The output shaft 3 has an outer coaxial cavity 3 a having an inner diameter larger than the outer diameter of any member attached to the outer wall 2 b of the coaxial cavity 2 a of the input shaft 2. Thereby, the outer wall 3b of the outer coaxial cavity 3a is formed in a substantially U-shape when viewed in cross section. Further, the output shaft 3 has an inner coaxial cavity 3c into which the connecting shaft 4 is inserted at the tip (end far from the steering wheel; lower end in the figure) in the outer coaxial cavity 3a, and the tip of the inner coaxial cavity 3c. The tip of the connecting shaft 4 is connected to the connecting pin 11. With this configuration, the torsional deformation of the entire length of the connecting shaft 4 is reflected in the rotational position shift between the outer wall 2 b of the coaxial cavity portion 2 a of the input shaft 2 and the outer wall 3 b of the outer coaxial cavity portion 3 a of the output shaft 3.

  In the present embodiment, the first magnet 5 is attached to the input shaft 2 and the pair of yokes 6 and 7 are attached to the output shaft 3. That is, the first magnet 5 is attached to the outer wall 2b of the coaxial cavity 2a, and the yokes 6 and 7 are attached to the outer wall 3b of the outer coaxial cavity 3a.

  The first magnet 5 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 first magnet 5 is composed of a permanent magnet in which a hard magnetic material is magnetized. The first magnet 5 is coaxial with the input shaft 2 and rotates integrally with the input shaft 2.

  As shown in FIG. 2, the yoke 6 has a ring 6 (a flat perforated disk) 6 a surrounding the first magnet 5 in a non-contact manner with a suitable narrow gap from the first magnet 5. A plurality of claws 6b are formed at the same pitch as the arrangement pitch of the same magnetic pole in one magnet 5 (for example, the arrangement pitch of N poles). The claw 6b is raised from the inner peripheral portion of the ring 6a along the first magnet 5 and extends in the axial direction (vertical direction in FIG. 2). Like the yoke 6, the yoke 7 has a plurality of claws 7b formed on the inner periphery of the ring 7a.

  The yokes 6 and 7 are arranged at different positions in the axial direction. Here, the yoke 7 is disposed at the same axial position as the end portion on the distal end side of the first magnet 5, and the yoke 6 is disposed at the same axial position as the end portion on the proximal end side of the first magnet 5. . More specifically, the yoke 7 is overlaid on the outer wall 3b surrounding the outer coaxial cavity 3a of the output shaft 3, the cylindrical spacer 3d is overlaid on the annular ring 7a of the yoke 7, and the yoke 6 is overlaid on the spacer 3d. It is done. The yokes 6 and 7 are combined so that the claws 6b and 7b face each other alternately. The yokes 6 and 7 and the outer wall 3b of the outer coaxial cavity 3a may be collectively molded with resin, and the spacer 3d may be formed by the resin molding. The yokes 6 and 7 are coaxial with the output shaft 3 and rotate integrally with the output shaft 3.

  As shown in detail in FIG. 3 (a), the yokes 6 and 7 have isosceles triangles when viewed from the side, and the claws 6b and 7b are staggered by shifting each other by a half pitch in the circumferential direction. It is attached coaxially to the output shaft 3 so as to face each other. The yokes 6 and 7 are for guiding the magnetic flux from the first magnet 5 with different distributions according to the torsional deformation of the connecting shaft 4. The yokes 6 and 7 are made of a soft magnetic material.

  As shown in FIG. 1, two outer yokes 12, 13 are provided that surround the circles 6 a, 7 a of the yokes 6, 7 in a non-contact manner with an appropriate narrow gap from the yokes 6, 7. The outer yokes 12 and 13 are attached to a fixed system (not shown) so as to be coaxial with the input shaft 2 and the output shaft 3. Proximity yokes 14 and 15 protruding from the outer yokes 12 and 13 are attached to predetermined positions in the circumferential direction of the two outer yokes 12 and 13 in order to narrow the gap between the two outer yokes 12 and 13, respectively. The outer yokes 12 and 13 are used to guide the magnetic flux from the yokes 6 and 7 and collect them in the proximity yokes 14 and 15, and the proximity yokes 14 and 15 collect magnetic flux between the proximity yokes 14 and 15. belongs to. The outer yokes 12 and 13 and the proximity yokes 14 and 15 are made of a soft magnetic material.

  The proximity yokes 14 and 15 have a rectangular parallelepiped shape or a curved shape along the outer periphery of the outer yokes 12 and 13. The two proximity yokes 14 and 15 have surfaces facing each other, and a gap narrower than that between the outer yokes 12 and 13 is formed between the two facing surfaces, and two magnetic detection elements are formed in the narrow gap. 8a and 8b are arranged. The two magnetic detection elements 8 a and 8 b are located in a region sandwiched between the yokes 6 and 7. The magnetic detection elements 8 a and 8 b are attached to the fixed system in the same manner as the outer yokes 12 and 13.

  As shown in the enlarged view in a circle of FIG. 2, one of the magnetic detection elements 8a is arranged with the detection surface F facing the base end direction (on the drawing), and the other magnetic detection element 8b F is arranged facing the front end direction (lower side in the figure). The two magnetic detection elements 8a and 8b 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. As shown in FIG. 10 described later, the two magnetic detection elements 8a and 8b may be arranged side by side in the axial direction.

  The detection direction of one magnetic detection element 8a is directed to the base end, and the detection direction of the other magnetic detection element 8b is directed to the distal end. Thus, the two magnetic detection elements 8a and 8b are provided with different detection directions.

  In FIG. 2, the lead wires 16 of the magnetic detection elements 8a and 8b are drawn by one for convenience, but may be plural. The lead wire 16 is connected to a calculation unit (not shown) and transmits the output from the magnetic detection elements 8a and 8b to the calculation unit.

  As shown in FIG. 1, the second magnet 9 is attached to the spacer 3 d of the output shaft 3. The spacer 3 d is a part of the output shaft 3, and the second magnet 9 is provided at a predetermined position in the circumferential direction of the output shaft 3 and rotates integrally with the output shaft 3. The second magnet 9 is disposed at substantially the same axial position as the two magnetic detection elements 8a and 8b. Specifically, the second magnet 9 is positioned at the axial position between the two magnetic detection elements 8a and 8b so that the magnetic pole 9a of the second magnet 9 faces the detection surface F of the two magnetic detection elements 8a and 8b. The center of 9 is arranged. The second magnet 9 is directed to either the north pole or the south pole of the magnetic pole 9a outward in the radial direction of the output shaft 3, and when the output shaft 3 is at the rotation reference position, the magnetic pole 9a has two magnetic detections. The position in the circumferential direction is determined so as to be closest to the elements 8a and 8b. The second magnet 9 is composed of a permanent magnet in which a hard magnetic material is magnetized. The rotation reference position may be set at any angle around the output shaft 3. For example, the rotation reference position is detected when the steering angle = 0 °, that is, when the steering wheel faces directly in front. On the other hand, the rotation angle of the output shaft 3 is detected by a rotation sensor (not shown) that can detect the rotation angle of the output shaft 3 in the range of 0 to 360 °. The number of times the rotation reference position is detected is increased or decreased according to the rotation direction, and the output angle of rotation of the rotation sensor is added to this number multiplied by 360 ° to obtain the steering angle.

  Next, an operation for detecting the torque received by the connecting shaft 4 will be described.

  As shown in FIG. 3A, in the neutral state in which the steering wheel is not steered and the connecting shaft 4 is not receiving torque, the yokes 6 and 7 have the tips of the claws 6b and 7b at the first ends. Indicates the boundary between the N pole and S pole of the magnet 5. As a result, in both the yoke 6 and the yoke 7, the areas where the claws 6b, 7b are opposed to the north pole of the first magnet 5 are equal to the areas where the claws 6 are opposed to the south pole. Since the magnetic flux entering from the N pole via the magnetic pole and the magnetic flux exiting to the S pole are equal, no magnetic flux is generated between the yokes 6 and 7.

  As shown in FIG. 3B, when the steering wheel is steered and the connecting shaft 4 receives torque, the connecting shaft 4 is attached to the input shaft 2 due to torsional deformation. The circumferential relative positions of the first magnet 5 and the yokes 6 and 7 attached to the output shaft 3 change. In the yoke 6, the area where the claw 6b faces the N pole is larger than the area facing the S pole. Therefore, the magnetic flux entering from the N pole through the claw 6b is larger than the magnetic flux exiting from the S pole through the claw 6b. In the yoke 7, the area where the claw 7 b faces the N pole is smaller than the area facing the S pole. Therefore, the magnetic flux entering from the N pole via the claw 7b is smaller than the magnetic flux exiting to the S pole via the claw 7b. As a result, a magnetic polarity difference occurs between the yokes 6 and 7, and a magnetic flux is generated between the yokes 6 and 7. This magnetic flux is guided by the outer yokes 12 and 13 (FIGS. 1 and 2) and collected in the proximity yokes 14 and 15.

  As a result, as shown in FIG. 4, a magnetic flux is generated between the two proximity yokes 14 and 15. As described in the enlarged view of the circle in FIG. 2, the two magnetic detection elements 8a and 8b 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. Therefore, as shown in FIG. 4, the detection surface F of the magnetic detection element 8a is close to the proximity yoke 14 on the proximal end side, and the detection surface F of the magnetic detection element 8b is close to the proximity yoke 15 on the distal end side. . The magnetic flux is detected by the two magnetic detection elements 8a and 8b, respectively. At this time, the magnitude of the magnetic field between the two proximity yokes 14 and 15 during the change from the state of FIG. 3A to the state of FIG. Is proportional to the circumferential displacement, that is, the torsional deformation of the connecting shaft 4. That is, the outputs of the magnetic detection elements 8a and 8b are proportional to the torque received by the connecting shaft 4.

5, each of the magnetic sensor 8a for the torque connection shaft 4 is subjected, it shows a change in the output V _t of 8b. However, it is assumed that the second magnet 9 is sufficiently separated from the magnetic detection elements 8a and 8b, and there is no influence of the magnetic field by the second magnet 9. Since the magnetic detection elements 8a and 8b output the detected magnetic field strength as a voltage, an output V _t proportional to the torque is obtained. The value of the output V _t when the connecting shaft 4 is in a neutral state not receiving torque is set to V _off . Since the detection directions of the two magnetic detection elements 8a and 8b 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.

  Next, an operation for detecting that the output shaft is at the rotation reference position will be described.

  In FIG. 1, the rotation reference position detection unit includes a second magnet 9 provided at a predetermined position in the circumferential direction of the output shaft 3 and magnetic detection elements 8 a and 8 b of the torque detection unit. When the second magnet 9 rotates as the output shaft 3 rotates, the circumferential position of the second magnet 9 relative to the magnetic detection elements 8a and 8b attached to the fixed system changes. As a result, the magnetic detection elements 8a and 8b detect a change in magnetic flux caused by the second magnet 9.

  That is, as shown in FIG. 6, the center of the second magnet 9 in a side sectional view is substantially in the same axial position as the centers of the magnetic detection elements 8a and 8b, and the magnetic pole 9a is radially outward ( (Left direction in the figure) The magnetic detection elements 8 a and 8 b are sandwiched between the proximity yokes 14 and 15. At this time, when the second magnet 9 is close to the magnetic detection elements 8a and 8b, the magnetic flux from the magnetic pole 9a of the second magnet 9 is almost in the radial direction, and the proximity yokes 14 and 15 are between the proximity yokes 14 and 15. The magnetic flux is induced by 15 and bent so as to be distributed to the magnetic detection elements 8a and 8b. The magnetic flux passing through the magnetic detection element 8a and the magnetic flux passing through the magnetic detection element 8b are in opposite directions. However, since the detection directions of the magnetic detection elements 8a and 8b are opposite to each other, the outputs of the magnetic detection elements 8a and 8b are equal to each other. .

FIG. 7 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 8a and 8b with the maximum output V _{Max over the} entire rotation angle. However, the torque index sensor 1 is in a neutral state in which the connecting shaft 4 is not receiving torque, and is not affected by the magnetic field from the first magnet 5. The value of the output V _i when the output shaft 3 is far from the rotation reference position, that is, when the second magnet 9 is sufficiently away from the magnetic detection elements 8a and 8b, is V _off . When the second magnet 9 is closest to the magnetic detection elements 8a and 8b, the output shaft 3 is at the rotation reference position, and the rotation angle at this time is expressed as 0 degree.

As shown in FIG. 7, the output V _i is maximum when the rotation angle of the output shaft 3 is 0 degree, and decreases rapidly 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.

When the magnetic field generated by the first magnet 5 described with reference to FIG. 4 and the magnetic field generated by the second magnet 9 described with reference to FIG. 6 are superimposed, the two magnetic detection elements 8a and 8b detect torque versus magnetic detection illustrated in FIG. The output characteristic and the rotation angle versus the magnetic detection output characteristic shown in FIG. 7 overlap. 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 obtained by performing the calculations of the expressions (1) and (2) using the outputs of the two magnetic detection elements 8a and 8b. Can be obtained.

However, V ₁ and V ₂ are outputs of the magnetic detection elements 8a and 8b. The values of the outputs V ₁ and V ₂ when the connecting shaft 4 is in a neutral state receiving no torque and the output shaft 3 is far from the rotation reference position are set as the offset value V _off .

Thus, the magnetic field by the first magnet 5 is applied in the opposite direction to the detection direction of the detection surface F of the two magnetic detection elements 8a and 8b, and the magnetic field by the second magnet 9 is applied to the two magnetic detection elements. Since the detection direction of the detection surface F of 8a and 8b is applied in the same direction, the difference between the outputs V ₁ and V ₂ of the two magnetic detection elements 8a and 8b is taken, and the offset value V _off is calculated from 1/2 of the difference. by subtracting, the output V _t of the torque is obtained. On the other hand, the two magnetic detection elements 8a, by subtracting the offset value V _off from half the sum of the outputs V _1, V ₂ of 8b, the output V _i of the rotation reference position is obtained.

Output V _i of the rotation reference position, because it corresponds to the magnetic field change caused by the rotation of the second magnet 9, by an appropriate value to the threshold, determining that the output shaft 3 is in the rotation reference position can do. 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.

  Next, equation (3) is derived from equation (2).

Theoretically V _d is always 0. Therefore, when the output V _i and the offset value V _off are appropriate known values, the actually detected outputs V ₁ and V ₂ of the magnetic detection elements 8a and 8b are substituted into the expression (3) to obtain V _{When d} is calculated, it is possible to determine whether the magnetic detection elements 8a and 8b are normally detecting or not detecting magnetic flux depending on whether or not V _d falls within the 0 ± threshold value.

As described above, according to the torque index sensor 1 of the present invention, the magnetic field of the first magnet 5 and the magnetic field of the second magnet 9 are superimposed and applied to the magnetic detection elements 8a and 8b. Since the detection directions of the magnetic detection elements 8a and 8b 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 8a and 8b. The rotation reference position can be detected. In other words, since one torque index sensor 1 includes a torque detection unit and a rotation reference position detection unit that use a common magnetic detection element 8a, 8b, it contributes to reduction in the number of parts and downsizing. A possible torque index sensor 1 is obtained.

  According to the torque index sensor 1 of the present invention, the rotational position shift between the first magnet 5 and the pair of yokes 6 and 7 is caused by the torsional deformation of the connecting shaft 4 so that the magnetic field changes. There are no mechanical elements such as gears that come into contact with each other, and it is highly reliable.

  According to the torque index sensor 1 of the present invention, the magnetic detection elements 8a and 8b can be attached to a fixed system instead of the rotation system such as the connecting shaft 4, the input shaft 2 and the output shaft 3, so the magnetic detection element 8a. , 8b power supply and signal extraction wiring are simple, reliable, and easy to maintain.

  According to the torque index sensor 1 of the present invention, the first magnet 5 is composed of a cylindrical magnet in which a plurality of N poles and S poles are alternately arranged at a predetermined pitch in the circumferential direction, Since the plurality of claws 6b and 7b are provided at a pitch that matches the magnetic pole arrangement pitch of the first magnet 5, the tips of the claws 6b and 7b are in the neutral state where the connecting shaft 4 is not receiving torque. By pointing to the boundary between the N pole and the S pole, a magnetic flux is generated between the yokes 6 and 7 in a neutral state regardless of changes in the magnetic field strength of the first magnet 5 due to temperature changes or the like. You can avoid it.

  According to the torque index sensor 1 of the present invention, since the proximity yokes 14 and 15 for collecting the magnetic flux are provided, the magnetic resistance in the magnetic circuit is reduced, and the magnetic detection element 8a is placed in the gap between the proximity yokes 14 and 15. , 8b can efficiently collect the magnetic flux generated by the first magnet 5 on the magnetic detection elements 8a, 8b.

  Next, another embodiment of the present invention will be described.

  As shown in FIG. 8, in the torque index sensor 80, the second magnet 9 is disposed at an axial position corresponding to the outside between the detection surfaces F of the two magnetic detection elements 8a and 8b. The second magnet 9 is arranged such that the N pole faces the radially inner side. Further, an auxiliary yoke 17 that guides the magnetic flux from the second magnet 9 to the magnetic detection element 8b is provided between the second magnet 9 and the magnetic detection element 8b. Other configurations are the same as those in FIG.

  As shown in FIG. 9, in the torque index sensor 80, the magnetic flux emitted from the N pole of the second magnet 9 enters the yoke 7 and the yoke 6 separately via the output shaft 3. The magnetic flux that has entered the yoke 7 enters the detection surface F of the magnetic detection element 8b from below in the figure via the outer yoke 13 and the proximity yoke 15. The magnetic flux that has entered the yoke 6 enters the detection surface F of the magnetic detection element 8a from above in the figure via the outer yoke 12 and the proximity yoke 14. A part of the magnetic flux emitted from the second magnet 9 enters the detection surface F of the magnetic detection element 8b from the lower side of the drawing via the auxiliary yoke 17 and the proximity yoke 15.

  The output of the magnetic detection element 8a has characteristics similar to FIG. 7 with respect to the rotation angle of the output shaft 3, and the output of the magnetic detection element 8b also has characteristics similar to FIG. 7 with respect to the rotation angle of the output shaft 3 ( However, in the configuration of FIG. 9, the direction of the magnetic flux is opposite to that of the configuration of FIG. Further, it is necessary to make the peak positions of the outputs of the magnetic detection elements 8a and 8b the same, but in this embodiment, by arranging the auxiliary yoke 17 at an appropriate position, the peak positions of both can be set. It is the same. Therefore, the output of the rotation reference position is obtained by taking the sum of the output of the magnetic detection element 8a and the output of the magnetic detection element 8b and subtracting the offset value from ½ thereof.

  As shown in FIG. 10, the two magnetic detection elements 8a and 8b may be arranged side by side in the axial direction. Also in this case, one of the magnetic detection elements 8a is arranged with the detection surface F facing the base end direction (illustrated above), and the other magnetic detection element 8b has the detection surface F facing the distal end direction (illustrated below). Arranged to face.

  The torque index sensor 100 shown in FIG. 11 arranges the second magnet 9 so that the center of the second magnet 9 is positioned at the axial position between the two magnetic detection elements 8a and 8b. An auxiliary yoke that guides the magnetic flux from the second magnet 9 to the two magnetic detection elements 8a and 8b on a straight line passing through the center of the magnet 9 and the middle of the two magnetic detection elements 8a and 8b (for example, radially outward). 17 is arranged. As a result, the magnetic flux from the second magnet 9 is more easily guided to the two magnetic detection elements 8a and 8b. This increases the difference between the output at the rotation reference position and the output at other positions. Therefore, the rotation reference position can be detected more accurately.

  In the embodiment described so far, the shape of the proximity yokes 14 and 15 is a rectangular parallelepiped or a curved shape. However, the proximity yokes 14 and 15 are not limited to this, and the shape of the side cross-section is L-shaped, etc. Various shapes can be used.

  In the embodiment described so far, the first magnet 5 is attached to the input shaft 2 and the yoke 6 is attached to the output shaft 3. However, the first magnet 5 is attached to the output shaft 3 and the yoke 6 may be attached to the input shaft 2.

  In the embodiments described so far, the first magnet 5 is a cylindrical magnet. However, the first magnet 5 does not have to be strictly cylindrical, and may be substantially cylindrical like a polygonal column. That's fine.

  In the embodiment described so far, the second magnet 9 is attached to the output shaft 3 and it is detected that the output shaft 3 is at the rotation reference position. However, if the second magnet 9 is attached to the input shaft 2, the input is performed. It can be detected that the shaft 2 is at the rotation reference position (reference of the steering wheel operation angle).

DESCRIPTION OF SYMBOLS 1 Torque index sensor 2 Input shaft 3 Output shaft 4 Connection shaft 5 First magnet 6, 7 Yoke 6b, 7b Claw 8a, 8b Magnetic detection element 9 Second magnet 10, 11 Connection pin 12, 13 Outer yoke 14, 15 Proximity yoke 16 Lead wire 17 Auxiliary yoke

Claims (7)

The input shaft and the output shaft are connected via a connecting shaft that is torsionally deformed, a first magnet is attached to one of the input shaft and the output shaft, and a pair of yokes facing each other is attached to the other,
In the region sandwiched between the pair of yokes, two magnetic detection elements are provided with different detection surface positions and detection directions,
A second magnet that provides another magnetic field superimposed on the magnetic field is provided at a predetermined position in a circumferential direction of the output shaft;
The torque received by the connecting shaft is detected from the difference between the two magnetic field strengths detected by the two magnetic detection elements,
A torque index sensor, wherein the output shaft is detected at a rotation reference position from the sum of two magnetic field intensities detected by the two magnetic detection elements . The first magnet 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, and is attached coaxially to the input shaft or the output shaft.
The yoke has a plurality of claws formed in a ring surrounding the first magnet in a non-contact manner at the same pitch as the arrangement pitch of the same magnetic pole in the first magnet. 2. The torque index sensor according to claim 1, wherein the yoke is arranged at different positions in the axial direction, and the yokes are mounted coaxially with respect to the output shaft or the input shaft with their claws shifted from each other by a half pitch in the circumferential direction. . 3. The torque index sensor according to claim 2, wherein two outer yokes are provided to surround each of the yokes with a distance from each of the yokes . Proximity yokes for narrowing the gap between the two outer yokes are respectively attached to predetermined positions in the circumferential direction of the two outer yokes, and the two magnetic detection elements are arranged between the two proximity yokes. The torque index sensor according to claim 3 . 5. The torque index sensor according to claim 1, wherein the second magnet is disposed at an axial position corresponding to an intermediate position between detection surfaces of the two magnetic detection elements . 5. The torque index sensor according to claim 1, wherein the second magnet is disposed at an axial position corresponding to an outer side between detection surfaces of the two magnetic detection elements . The torque index sensor according to any one of claims 1 to 6, further comprising an auxiliary yoke for guiding magnetic flux from the second magnet to the two magnetic detection elements .

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