JP2008281384A - Torque detection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a torque detection device capable of discriminating ordinary steering from an influence of an external magnetic field. <P>SOLUTION: This torque detection device is equipped with a pair of a first main magnetism collector 71 and a first sub-magnetism collector 72 provided circularly, a pair of a second main magnetism collector 73 and a second sub-magnetism collector 74 provided circularly, a main Hall IC 75 interposed between a magnetism collection end 71a of the first main magnetism collector 71 and a magnetism collection end 73a of the second main magnetism collector 73 facing thereto, and a sub-Hall IC 76 interposed between a magnetism collection end 72a of the first sub-magnetism collector 72 and a magnetism collection end 74a of the second sub-magnetism collector 74 facing thereto. The device is provided with a shield member 77 only on the 'main' side for differentiating mutually each sensitivity to the external magnetic field of a magnetic circuit part from the main magnetism collectors 71, 73 to the main Hall IC 75 and a magnetic circuit part from the sub-magnetism collectors 72, 74 to the sub-Hall IC 76. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a torque detection device used for detection of steering torque of an electric power steering device.

  An electric power steering device such as an automobile is provided with a torque detection device for detecting a steering torque of a driver and generating an appropriate steering assist force. The torque detection device includes a magnetic device (permanent magnet / yoke) that generates a magnetic flux corresponding to a torsion angle (that is, steering torque) of a torsion bar connected to the steering wheel. The steering torque is detected by a magnetism collecting ring and a Hall IC (see, for example, Patent Documents 1 to 3).

  In such a torque detection device using a Hall IC, there is a possibility that the steering of the Hall IC may be raised and steering assistance may be performed even though the steering is not being performed, under the influence of an external magnetic field. Thus, a configuration has been proposed in which a shield member that shields magnetism from the outside is attached so as to cover the outer surface of the torque detection device (see, for example, Patent Document 2). As an external magnetic field that affects the torque detection device, for example, a magnetic field generated around a high-voltage transmission line laid on a large-scale bridge, or a road-embedded heater used for melting snow in a cold region, for example. There is a magnetic field.

Japanese Patent Laying-Open No. 2005-265593 (FIG. 1) JP 2006-71326 A (FIGS. 1 and 3) Japanese Patent Laying-Open No. 2004-125717 (FIG. 1)

However, for an external magnetic field exceeding the shielding ability of the shield member, the torque detection device itself cannot be distinguished from normal steering, and it produces an output as if it was normal steering, and steering assistance is performed against the will of the driver. there is a possibility. Also, when a user installs an audio speaker in the vicinity of the torque detection device, a strong external magnetic field that cannot be shielded by the shield member may be generated, and the torque detection device outputs the same output as in normal steering. May occur.
In view of this problem, an object of the present invention is to provide a torque detection device that can distinguish between normal steering and the influence of an external magnetic field.

  A torque detector according to the present invention includes a cylindrical magnetic device that generates a magnetic flux corresponding to a torsion angle between an input shaft and an output shaft connected to each other via a torsion bar, and a circular shape along an outer peripheral surface of the magnetic device. A pair of arcuately provided first and second submagnets that capture the magnetic fluxes generated by the magnetic device with equal sensitivity, and arcuate along the outer peripheral surface of the magnetic device A pair of second main magnetic collectors and second sub-magnetic collectors that capture the magnetic fluxes generated by the magnetic device with equal sensitivity; and a magnetic collector end portion of the first main magnetic collector; A main Hall IC interposed between the magnetic flux collecting end portions of the second main magnetic collector facing the magnetic flux collector, the magnetic flux collecting end portions of the first auxiliary magnetic flux collector, and the second auxiliary magnetic flux collector facing the main Hall IC. Sub-Hall IC interposed between the magnetic flux collecting end portions of each of the main magnetic flux collectors, The magnetic circuit section up to the Hall IC and the magnetic circuit section from each of the sub magnetic collectors to the sub Hall IC are provided with means or arrangements for making the sensitivity to an external magnetic field unrelated to the magnetic device different from each other. is there.

  In the torque detection device configured as described above, the magnetic flux generated by the magnetic device by steering is captured equally by the first and second main magnetic current collectors and the first and second sub magnetic current collectors. The sub Hall IC produces an equal output. On the other hand, for an external magnetic field, a sensitivity difference occurs between the magnetic circuit section from each of the main current collectors to the main Hall IC and the magnetic circuit section from each of the sub-magnetic current collectors to the sub Hall IC, and the output is not good. It will be equal.

Further, the means may be a shield member that shields only one of each of the main magnetic collector and each of the sub-magnetic collector from the external magnetic field.
In this case, the output of the main / sub Hall IC can be easily varied with respect to the external magnetic field.

The arrangement may be that the directions of the main Hall IC and the sub Hall IC are made different from each other.
In this case, the output of the main / sub Hall IC can be made different with respect to the external magnetic field without depending on the shield member.

The shield member may be formed with a shield portion that shields the Hall IC on the side of the magnetic collector to be shielded from the external magnetic field.
In this case, the output of the main / sub Hall IC can be made different from the external magnetic field more reliably.

  According to the torque detection device of the present invention, the influence of the external magnetic field can be distinguished from normal steering as a result of non-uniformity of the outputs of the main and sub Hall ICs. Therefore, if the steering assist is not performed if the output is not uniform, steering contrary to the will of the driver can be prevented.

  FIG. 6 is a diagram showing a schematic configuration of an electric power steering apparatus for an automobile. In the figure, the steering wheel 101 is connected to the input shaft 1. The input shaft 1 is connected to the output shaft 2 via a torsion bar 3. The output shaft 2 steers the steering wheel 105 via the rack and pinion 104. The torque detection device 100 detects the steering torque based on the twist angle of the torsion bar 3, and the output signal is sent to the ECU 102. The ECU 102 drives the motor 103 based on the output of the torque detection device 100 and applies a steering assist force to the output shaft 2.

  FIG. 1 is an exploded perspective view showing the configuration of the torque detection device 100 according to the first embodiment of the present invention. In the figure, an input shaft 1 and an output shaft 2 are connected to each other via a thin torsion bar 3. For the convenience of illustration, the torsion bar 3 is a single bar connected from the input shaft 1 to the output shaft 2 although not shown in the middle. A cylindrical permanent magnet 4 having 24 poles (N, S poles × 12) magnetized in the circumferential direction is attached to the input shaft 1.

  On the other hand, a cylindrical yoke 5 including magnetic yokes 51 and 52 made of a soft magnetic material is attached to the output shaft 2. The permanent magnets 4 are inserted inside the yoke 5 and face each other with a slight radial gap between the permanent magnet 4 and the inner peripheral surface of the yoke 5. The permanent magnet 4 and the yoke 5 constitute a cylindrical magnetic device 6 that generates a magnetic flux corresponding to the torsion angle between the input shaft 1 and the output shaft 2 connected to each other via the torsion bar 3. Moreover, the yoke 5 is inserted inside the detection device 7, and both face each other with a slight gap in the radial direction. The detection device 7 has a pair of magnetic current collectors 71 to 74 (details will be described later) in an arc shape. The output (voltage) of the detection device 7 is taken out by the harness 8. In addition, each said member is arrange | positioned coaxially mutually. The detection device 7 can be attached to a predetermined location using a hole 7b formed in the attachment portion 7a.

  FIG. 2 is a front view showing only the detection device 7. In addition to the mounting portion 7a, the detection device 7 is formed so as to rise in the center of the magnetic flux collector holding portion 7c containing the magnetic current collectors 71 to 74 and the Hall ICs 75 and 76, and to the center of the mounting portion 7a. A circuit housing portion 7d in which a circuit portion (not shown) including a capacitor is built, and a portion that is further raised on the back side of the circuit housing portion 7d, and that includes a portion for connecting the circuit portion and the harness 8 by heat caulking. And a connecting portion 7e. Each part is integrally formed by a resin mold, and only the inner peripheral surfaces of the magnetic current collectors 71 to 74 are exposed.

  1 and 2, a shield member 77 made of a magnetic material (iron) is attached to one half (on the front side in FIG. 1) of the outer peripheral surface of the magnet collector holding portion 7c. 1 and 2, a shield member 78 made of a magnetic material (iron) is also attached to the circuit housing portion 7d so as to cover it. The shield member 77 serves to shield the magnetic collectors 71 and 73 from an external magnetic field unrelated to the magnetic device 6. The shield member 78 mainly serves to shield the Hall ICs 75 and 76 from an external magnetic field.

  FIG. 3 is an exploded perspective view of the magnetic current collectors 71 to 74 and the Hall ICs 75 and 76 in the detection device 7. In the figure, a first main magnetic current collector 71 and a first sub magnetic current collector 72 are provided in a pair of arcs (substantially semicircle) along the outer peripheral surface of the magnetic device 6 (FIG. 1). The magnetic fluxes generated by 6 are captured with equal sensitivity to each other. Similarly, the second main magnetic collector 73 and the second sub magnetic collector 74 are displaced along the outer peripheral surface of the magnetic device 6 and in the axial direction from the first main magnetic collector 71 and the first sub magnetic collector 72. A pair of circular arcs are provided at positions, and magnetic fluxes generated by the magnetic device 6 are captured with equal sensitivity.

  A magnetism collecting end portion 71a projecting from the end of the first main magnetism collecting body 71 and a magnetism collecting end portion 73a projecting from the end of the second main magnetism collecting body 73 are opposed to each other in the axial direction. The main hall IC 75 is interposed between the two. Similarly, the magnetism collecting end portion 72a projecting from the end portion of the first sub magnetism collecting body 72 and the magnetism collecting end portion 74a projecting from the end portion of the second sub magnetism collecting body 74 are opposed to each other in the axial direction. A sub Hall IC 76 is interposed between them.

  FIG. 4 is a perspective view showing an arrangement after assembly in which a shield member 77 is added to each of the magnetic current collectors 71 to 74 and the Hall ICs 75 and 76. Due to the presence of the shield member 77, the first and second main magnetic current collectors 71 and 73 are shielded against an external magnetic field unrelated to the magnetic device 6. Therefore, the magnetic circuit section from the first and second main magnetic collectors 71 and 73 to the main Hall IC 75 is more resistant to external magnetic fields than the magnetic circuit section from the first and second sub magnetic collectors 72 and 74 to the sub Hall IC 76. Sensitivity deteriorates. That is, the output of the Hall IC 75 with respect to the external magnetic field is smaller than the output of the Hall IC 76. On the other hand, for the internal magnetic field, that is, the magnetic flux generated from the magnetic device 6, the magnetic circuit section from the first and second main magnetic collectors 71 and 73 to the main Hall IC 75 and the first and second sub magnetic collectors 72 and 74. To the sub Hall IC 76 have the same sensitivity, and the outputs of the Hall ICs 75 and 76 for the magnetic flux generated from the magnetic device 6 are the same.

  In the torque detection device 100 configured as described above, when the driver does not operate the steering wheel 101 (FIG. 6), the output of the Hall ICs 75 and 76 is determined from the positional relationship between the permanent magnet 4 and the magnetic yokes 51 and 52. Is adjusted to 0. FIG. 5A is a graph showing the relationship of the sensor signal (the output of the Hall IC) with respect to the steering torque when there is no influence of the external magnetic field. The sensor signal V1 (solid line) from the main hall IC 75 increases in the positive direction in proportion to the steering torque. The sensor signal V2 (broken line) from the sub hall IC 76 increases in the negative direction in proportion to the steering torque. The gradient of increase is the same, and the absolute values of the sensor signals V1 and V2 are the same.

  When a steering torque is applied to the input shaft 1 by operating the steering wheel 101 by the driver, the torsion bar 3 is twisted, and a relative twist angle is generated between the input shaft 1 and the output shaft 2. This twist angle changes according to the steering torque. The magnetic device 6 generates a magnetic flux corresponding to the twist angle. The magnetic flux is captured with equal sensitivity by the first and second main magnetic collectors 71 and 73 and the first and second sub magnetic collectors 72 and 74, and the sensor signals V1 and V2 from the Hall ICs 75 and 76 are shown in FIG. Appears as shown in

On the other hand, when affected by an external magnetic field, as shown in FIG. 5B, the main Hall IC 75 on the first and second main magnetic current collectors 71 and 73 side shielded by the shield member 77, and the first The sensor signals V1 and V2 are different from those of the sub Hall IC 76 on the second sub magnet collectors 72 and 74 side, and the absolute value of the sensor signal V1 from the main Hall IC 75 is smaller. This is the same whether the steering torque is 0 or the steering torque is applied.
In this way, based on a simple configuration in which the shield member 77 is provided only on one side, whether the output of the two Hall ICs 75 and 76 is equal or non-uniform is affected by normal steering or an external magnetic field. Can be identified.

  Accordingly, in the ECU 102 (FIG. 6), when the absolute values of the sensor signals V1 and V2 from the two Hall ICs 75 and 76 are equal, the steering assist force is determined based on that and the motor 103 (FIG. 6) is driven. . On the other hand, when the absolute values of the sensor signals V1 and V2 from the two Hall ICs 75 and 76 are unequal, it is determined that they are affected by an external magnetic field, and steering assistance is not performed from the viewpoint of fail-safe. In this way, erroneous steering assistance due to the influence of the external magnetic field can be prevented.

FIG. 7 is a front view of the detection device 7 in the torque detection device 100 according to the second embodiment of the present invention. FIG. 8 is a perspective view of the main part. Other configurations are the same as those in the first embodiment.
As apparent from comparison with FIG. 2, in FIG. 7, the main Hall IC 75 is not located symmetrically with the sub Hall IC 76 and is slightly shifted to the right. In addition, the shield member 77 includes a shield portion 77a that protrudes not only on the side surface but also on the front surface side of the current collector holding portion 7c. Yes.

  Therefore, the magnetic circuit portion from the first and second main magnetic collectors 71 and 73 to the main Hall IC 75 is externally compared with the magnetic circuit portion from the first and second sub magnetic collectors 72 and 74 to the sub Hall IC 76. The sensitivity difference with respect to the magnetic field becomes larger than that in the first embodiment. As a result, the sensor signal of the main Hall IC 75 when affected by the external magnetic field can be more reliably made smaller in absolute value than the sensor signal of the sub Hall IC 76.

  FIG. 9 is an exploded perspective view of the magnetic current collectors 71 to 74 and the Hall ICs 75 and 76 in the torque detection device 100 according to the third embodiment of the present invention. FIG. 10 is a perspective view showing an arrangement after assembly in which the shield members 79 are added to the magnetic current collectors 71 to 74 and the Hall ICs 75 and 76. The first and second sub magnetic current collectors 72 and 74 and the sub hall IC 76 are the same as those in the first embodiment. On the other hand, regarding the first and second main magnetic collectors 71 and 73, the way of providing the magnetic flux collecting end portions 71a and 73a is different from that of the first embodiment.

  That is, the magnetism collecting end portion 71 a is provided so as to protrude in the axial direction toward the second main magnetism collecting body 73. Similarly, the magnetism collecting end portion 73a is provided so as to protrude in the axial direction toward the first main magnetism collecting body 71, and is offset in the circumferential direction from the magnetism collecting end portion 71a. It can be sandwiched between. Further, the main Hall IC 75 has a sensor surface (mainly a surface through which magnetic flux passes) that is 90 degrees away from the sub Hall IC 76. In FIG. 10, a U-shaped shield member 79 shields all of the main and sub magnetic collectors 71 to 74 from an external magnetic field. Other configurations are the same as those in the first embodiment.

  In FIG. 10, the outputs of the two Hall ICs 75 and 76 are equal to the magnetic flux of the magnetic device 6 (FIG. 1), as in the first embodiment. On the other hand, when an external magnetic field exceeding the shielding capability of the shield member 79 is present, the sensor output is different because the orientation of the main Hall IC 75 is different from that of the sub Hall IC 76. For example, the sensor output of the main Hall IC 75 is It becomes smaller than the sensor output of Hall IC. That is, by making the directions of the main Hall IC 75 and the sub Hall IC 76 different from each other, the sensitivity to the external magnetic field is different, and the output non-uniformity is intentionally generated.

  Thus, regardless of the shield member, whether the output from the two Hall ICs 75 and 76 is equal or non-uniform is affected by normal steering or an external magnetic field, as in the first embodiment. Can be identified. Note that the difference in orientation between the main Hall IC 75 and the sub Hall IC 76 is not limited to 90 degrees, but the difference in sensor output is most likely to occur when the angle is 90 degrees.

In each of the above embodiments, the “main” and “sub” relationships of the magnetic current collectors 71 to 74 and the Hall ICs 75 and 76 may be reversed. The shield member 77 only needs to be on one side, and may be on either the “main” or “sub” side.
Further, the shield member 79 (FIG. 10) of the third embodiment that provides a shielding effect for both “main” and “sub” is added to only one (“main” side) shield member 77 in the first and second embodiments. You may use together.

  In addition, the magnetic current collectors 71 to 74 in each of the above embodiments have a semicircular arc shape, but it is also possible to arrange them so that the “main” and “sub” overlap each other as an arc exceeding a semicircle (180 degrees). is there. However, it is necessary that the “main” and “sub” have the same size as each other so that they can receive the magnetic flux equally.

It is a disassembled perspective view which shows the structure of the torque detection apparatus by 1st Embodiment of this invention. It is a front view which shows only the detection apparatus in the torque detection apparatus of FIG. It is a disassembled perspective view of the magnetic collector and Hall IC in a detection apparatus. It is a perspective view which shows the arrangement | positioning after the assembly which added the shield member to the magnetic collector and Hall IC. It is a graph which shows the relationship of the sensor signal (output of Hall IC) with respect to steering torque in the case where there is no influence of an external magnetic field. It is a figure which shows schematic structure of the electric power steering apparatus of a motor vehicle. It is a front view of the detection apparatus in the torque detection apparatus by 2nd Embodiment of this invention. It is a perspective view of the principal part in the torque detector by 2nd Embodiment. It is a disassembled perspective view of the magnetic collector and Hall IC in the torque detector by 3rd Embodiment of this invention. FIG. 10 is a perspective view showing an arrangement after assembly in which a shield member is added to the magnetic current collector and Hall IC shown in FIG. 9.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Input shaft 2 Output shaft 3 Torsion bar 6 Magnetic apparatus 71 1st main magnetism collector 72 1st submagnetism collector 73 2nd main magnetism collector 74 2nd submagnetism collector 75 Main Hall IC
76 Deputy Hall IC
77,79 Shield member 77a Shield part

Claims (4)

A cylindrical magnetic device that generates a magnetic flux corresponding to a torsion angle between an input shaft and an output shaft connected to each other via a torsion bar;
A pair of first magnetic current collectors and first secondary magnetic current collectors that are provided in a circular arc shape along the outer peripheral surface of the magnetic device and that capture magnetic fluxes generated by the magnetic device with equal sensitivity to each other;
A second main magnetic current collector and a second sub magnetic current collector, which are provided in a pair of arcs along the outer peripheral surface of the magnetic device, and capture magnetic fluxes generated by the magnetic device with equal sensitivity to each other;
A main Hall IC interposed between the current collecting end of the first main current collector and the current collecting end of the second main current collector facing the first main current collector;
A sub Hall IC interposed between the magnetic flux collecting end portion of the first sub magnetic flux collector and the magnetic flux collecting end portion of the second sub magnetic flux collector facing the first magnetic flux collector;
The magnetic circuit section from each of the main magnetic collectors to the main Hall IC and the magnetic circuit section from each of the sub magnetic collectors to the sub Hall IC have different sensitivities to external magnetic fields that are independent of the magnetic device. Torque detection device characterized by having means or arrangement for applying the torque.   The torque detection device according to claim 1, wherein the means is a shield member that shields only one of each of the main magnetic collector and each of the sub-magnetic collector from the external magnetic field.   The torque detection device according to claim 1, wherein the arrangement is to make the directions of the main Hall IC and the sub Hall IC different from each other.   The torque detection device according to claim 2, wherein the shield member is formed with a shield portion that shields the Hall IC on the side of the magnetic collector to be shielded from the external magnetic field.

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