JP2019045477A - Torque detection device and magnetic sensor module - Google Patents

Abstract

To provide a torque detection device improving an SN ratio of a magnetic flux to be detected by magnetic sensors.SOLUTION: A torsion bar 13 of a torque detection device 10 converts torque applied between an input shaft 11 and an output shaft 12 into torsional deformation. A pair of yokes 31 and 32 is formed of a soft magnetic material, fixed to the output shaft 12, faces each other in an axial direction, and forms a magnetic circuit within a magnetic field of a multipolar magnet 14 fixed to the input shaft 11. A pair of magnetic flux guide members 511 and 521 is formed of a soft magnetic material, where the pair of yokes 31 and 32 and bodies 60 face each other and guide a magnetic flux of the magnetic circuit. Magnetic sensors 71 and 72 are disposed at extension parts 61 and 62 and detect the magnetic flux guided by the magnetic flux guide members 511 and 521. The magnetic flux guide members 511 and 521 are so configured that, at branch parts of the bodies 60 to the extension parts 71 and 72, a magnetic permeance between the magnetic flux guide members 511 and 521 and the yokes 31 and 32 per unit of area is greater than that at the peripheral end parts thereof.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a torque detection device and a magnetic sensor module used in the torque detection device.

  2. Description of the Related Art Conventionally, a torque detection device that detects a change in magnetic flux caused by relative rotation between a multipolar magnet and a yoke by a magnetic sensor and detects torque applied to a torsion bar based on an output signal of the magnetic sensor is known. In addition, in this type of torque detection device, a configuration using a magnetic flux guiding member that collects magnetic flux of a yoke and guides it to a magnetic sensor is known.

  For example, in the configuration disclosed in Patent Document 1, the magnetism collecting ring corresponding to the magnetic flux guiding member has a distance from the central axis of the multipolar magnet (or yoke) to the inner edge of the magnetism collecting ring. ) In the direction connecting the central axis and the magnetic sensor. This suppresses periodic fluctuations in the magnetic flux generated in the magnetic circuit when the multipolar magnet and the yoke rotate synchronously with a constant torque. Hereinafter, in this specification, the noise due to the periodic fluctuation of the magnetic flux is referred to as “swinging noise”.

JP 2012-237727 A

  In this type of torque detection device, since the output voltage of the magnetic sensor is amplified by an amplifier and transmitted to the control device, it is important to improve the SN ratio by increasing the signal and reducing the noise. However, in the configuration of Patent Document 1, the axially facing area between the magnetic flux guiding member and the yoke is relatively small in the vicinity of the magnetic sensor, and depending on the embodiment, the facing area between the magnetic flux guiding member and the yoke is small. 0. For this reason, when the magnetic flux guide member and the yoke are opposed to each other at a portion away from the magnetic sensor and the magnetic flux is collected, the magnetic resistance is higher than when the magnetic flux is collected near the magnetic sensor, and the amount of magnetic flux collected by the sensor is reduced. Therefore, since the whirling noise is reduced and the signal is also reduced, there is a problem that improvement of the SN ratio cannot be expected.

  The present invention has been made in view of the above problems, and an object thereof is to provide a torque detection device that improves the SN ratio of magnetic flux detected by a magnetic sensor, and a magnetic sensor module used in the torque detection device. There is to do.

  The torque detection device of the present invention includes a torsion bar (13), a multipolar magnet (14), a pair of yokes (31, 32), one or more magnetic flux induction members (51, 52), and one The above magnetic sensors (71, 72). The torsion bar connects the first shaft (11) and the second shaft (12) on the same axis, and converts the torque applied between the first shaft and the second shaft into a torsional displacement. The multipolar magnet is fixed to one end of the first shaft or the torsion bar, and N poles and S poles are alternately arranged in the circumferential direction. A pair of yokes is formed of a soft magnetic material, is fixed to the second shaft or the other end of the torsion bar on the outer side of the multipolar magnet, and is opposed to each other in the axial direction. Form.

  The magnetic flux guiding member is formed of a soft magnetic material, and at least one yoke and the main body (60) face each other to induce magnetic flux of the magnetic circuit. A magnetic sensor is installed in the main body of the said magnetic flux induction member, or the extended contact part (61, 62) branched from the said main body, and detects the magnetic flux induced | guided | derived by the magnetic flux induction member. Here, in the projection in the axial direction of the yoke, when there is one magnetic sensor, the magnetic sensor and the central axis of the yoke are connected, and when there are a plurality of magnetic sensors, the intermediate position of the plurality of magnetic sensors and the central axis of the yoke are connected. The connecting virtual line is defined as a reference line (X). Further, the portions corresponding to both ends in the circumferential direction of the yoke in the opposing range between the main body of the magnetic flux guiding member and the yoke with the reference line interposed therebetween are defined as the peripheral end portions (63, 64) of the main body of the magnetic flux guiding member.

  In the first aspect of the present invention, the magnetic flux guiding member is a branching portion to the magnetic sensor installation site or the extending contact portion in the main body, and “per unit area between the magnetic flux guiding member and the yoke compared to the peripheral end portion”. The "magnetic permeance" is increased. The reference numerals corresponding to the magnetic flux guide members of the first aspect correspond to those obtained by excluding “560, 570” of the second aspect from the general reference numerals “51, 52”. Thereby, since the signal which a magnetic sensor detects becomes large, SN ratio can be improved.

  Preferably, the distance from the branch part to the magnetic sensor installation part or extension part in the main body of the magnetic flux guide member to the central axis of the yoke is shorter than the distance from the peripheral end part to the central axis of the yoke. For example, the magnetic flux guiding member is preferably a straight line in which the side on the central axis side of the yoke is orthogonal to the reference line. In particular, since the main body of the magnetic flux guiding member is formed in a rectangular belt shape, the magnetic flux guiding member can be made small. For example, when a magnetic flux induction member is manufactured by punching a sheet metal material with a press, the yield can be improved by designing the shape of the magnetic flux induction member.

  In addition, in the configuration in which the torque detection device includes two magnetic sensors arranged symmetrically with respect to the reference line, the magnetic flux branches from the reference line side of the magnetic flux guiding member toward the two magnetic sensors, so that the magnetic sensor It is considered that the noise to be transmitted is reduced. As a result, the SN ratio of the magnetic flux detected by the magnetic sensor can be further improved.

  The present invention is also used in the torque detection device described above, and is provided as a magnetic sensor module in which a magnetic flux guiding member and a magnetic sensor are integrally configured. For example, the magnetic sensor module is configured by resin molding integrally. This magnetic sensor module can be manufactured and sold independently as a component constituting the torque detection device, and has an effect of improving the SN ratio when used in the torque detection device.

  In the second aspect of the present invention, the torque detection device includes two magnetic sensors. The magnetic flux guiding members (560, 570) are straight lines whose sides on the central axis side of the yoke are orthogonal to the reference line, and the two magnetic sensors are arranged symmetrically with respect to the reference line. The magnetic flux guide member is a part where the magnetic sensor is installed in the main body or a branch part to the extension part, and the magnetic permeance per unit area between the magnetic flux guide member and the yoke is smaller than the part on the reference line. Has been. In the second aspect, the signal detected by the magnetic sensor is smaller than that in the first aspect. However, when the noise reduction effect due to the magnetic flux branching from the reference line side of the magnetic flux guiding member toward the two magnetic sensors is greater, the SN ratio is improved. In particular, since the main body of the magnetic flux guiding member is formed in a rectangular belt shape, the magnetic flux guiding member can be made small.

The disassembled perspective view of the torque detection apparatus by each embodiment (a magnetic sensor module is 1st Embodiment). 1 is a schematic configuration diagram of an electric power steering device to which a torque detection device of each embodiment is applied. The (a) top view and (b) side view of the magnetic sensor module of a 1st embodiment. FIG. 3 is an axial sectional view of the magnetic sensor module according to the first embodiment. (A) Correlation diagram between distance from reference line and magnetic permeance in first embodiment, (b) A diagram for explaining reduction of run-out fluctuation according to the first embodiment. The figure explaining the manufacturing yield improvement by the magnetic flux guide member of 1st Embodiment. The top view of the magnetic sensor module of 2nd Embodiment. The magnetic sensor module of 3rd Embodiment (a) Top view, (b) Side view. (A) Top view of magnetic sensor module of 4th Embodiment, (b) Side view. An axial direction sectional view of a magnetic sensor module of a 4th embodiment. An axial direction sectional view of a magnetic sensor module of a 5th embodiment. An axial direction sectional view of a magnetic sensor module of a 6th embodiment. (A) Top view of magnetic sensor module and yoke of 7th Embodiment, (b) Side view. An axial direction sectional view of a magnetic sensor module and a yoke of a 7th embodiment. (A) Top view of magnetic sensor module of 8th Embodiment, (b) Side view. The top view of the magnetic sensor module of 9th Embodiment. (A) Top view of magnetic sensor module of 10th Embodiment, (b) Side view. The correlation figure of the distance from the reference line and magnetic permeance in 10th Embodiment. The top view of the magnetic sensor module of 11th Embodiment. The top view of the magnetic sensor module of 12th Embodiment. (A) Top view of magnetic sensor module of 13th Embodiment, (b) Axial direction sectional drawing. (A) Top view of magnetic sensor module of 14th Embodiment, (b) Axial direction sectional drawing. The figure which shows the length of the preferable main body of the linear magnetic flux guide member of 1st Embodiment. The figure which shows the relationship between the number of radiation | emission range magnetic poles in a linear magnetic flux guidance member, and a whirling noise. The figure which shows the length of the preferable main body of the circular-arc-shaped magnetic flux guide member of 3rd Embodiment. The figure which shows the relationship between the number of radiation | emission range magnetic poles in a circular-arc-shaped magnetic flux guide member, and a whirling noise. The figure which shows the relationship between the number of radiation | emission range magnetic poles, and a whirling noise in case the number of magnetic poles of a multipolar magnet is (a) 12 poles, (b) 20 poles. The figure (1) which shows the form of the magnetic flux guide member of other embodiment. The figure (2) which shows the form of the magnetic flux guide member of other embodiment. The figure (3) which shows the form of the magnetic flux guide member of other embodiment. The figure (4) which shows the form of the magnetic flux guide member of other embodiment. (A) Top view of the yoke of other embodiment, (b) Partial perspective view. The reference figure which shows the flow of the magnetic flux from the nail | claw of a yoke to a ring.

Hereinafter, a plurality of embodiments of a torque detection device will be described with reference to the drawings. In a plurality of embodiments, substantially the same configuration is denoted by the same reference numeral and description thereof is omitted.
Further, the following first to fourteenth embodiments are collectively referred to as “this embodiment”. The torque detection device of this embodiment is applied to an electric power steering device for assisting a steering operation of a vehicle.

  First, a schematic configuration of an electric power steering apparatus to which the torque detection device of each embodiment is applied will be described with reference to FIG. The electric power steering device 90 shown in FIG. 2 is a column assist type, but can be similarly applied to a rack assist type electric power steering device. A steering shaft 94 connected to the handle 93 is provided with a torque detection device 10 for detecting steering torque. A pinion gear 96 is provided at the tip of the steering shaft 94, and the pinion gear 96 meshes with the rack shaft 97. A pair of wheels 98 are rotatably connected to both ends of the rack shaft 97 via tie rods or the like. The rotational motion of the steering shaft 94 is converted into a linear motion of the rack shaft 97 by the pinion gear 96, and the pair of wheels 98 are steered.

  The torque detection device 10 is provided between the input shaft 11 and the output shaft 12 constituting the steering shaft 94, detects the steering torque applied to the steering shaft 94, and outputs it to the ECU 91. The ECU 91 controls the output of the motor 92 according to the detected steering torque. The steering assist torque generated by the motor 92 is decelerated via the reduction gear 95 and transmitted to the steering shaft 94.

  Here, the form in which the torque detection device 10 includes two magnetic sensors 71 and 72 and outputs two values trq1 and trq2 as steering torque corresponds to the first to tenth embodiments and the like. By adopting a configuration in which the torque information used for control of the ECU 91 is redundantly output, even if one of the torque information becomes unusable due to a failure of the magnetic sensor or the arithmetic circuit, the ECU 91 uses the torque information of the other motor 92. Can be continued. Therefore, such a redundant configuration is particularly effective in the electric power steering apparatus 90 that requires high reliability. However, as in the eleventh and twelfth embodiments, the torque detection device 10 may include a single magnetic sensor 71.

  Next, the overall configuration of the torque detection device 10 will be described with reference to FIGS. 1 and 2. As shown in FIG. 2, the torque detection device 10 includes a torsion bar 13, a multipole magnet 14, a pair of yokes 31 and 32, one or more magnetic flux guiding members 51 and 52, and one or more magnetic sensors 71. 72, etc. A unit including one or more magnetic flux guide members 51 and 52 and one or more magnetic sensors 71 and 72 is referred to as a magnetic sensor module 50.

  Here, in FIG. 2 schematically showing the shapes of the constituent members, “50” is used as a code including the magnetic sensor module of each embodiment, and “51, 52” is used as a code including the magnetic flux guide member of each embodiment. Is used. On the other hand, in FIG. 1 specifically showing the shape of the magnetic flux guiding member of the first embodiment, the reference numeral “501” of the magnetic sensor module of the first embodiment and the reference numeral “511” of the magnetic flux guiding member of the first embodiment. 521 ". Thus, each embodiment differs in the specific shape of the magnetic flux induction members 51 and 52 and the number of the magnetic sensors 71 and 72. However, in the description of this part, the detailed shape of the magnetic flux guide members 511 and 521 in FIG. 1 is not mentioned, and only the entire configuration of the torque detection device 10 is referred to.

  As shown in FIGS. 1 and 2, the torsion bar 13 is fixed to the input shaft 11 as the “first axis” at one end side and to the output shaft 12 as the “second axis” at the other end with the fixing pins 15. The input shaft 11 and the output shaft 12 are connected coaxially with the central axis O. The torsion bar 13 is a rod-like elastic member, and converts the steering torque applied to the steering shaft 94 into a torsional displacement. The multipolar magnet 14 is fixed to the input shaft 11, and N poles and S poles are alternately arranged in the circumferential direction. In this embodiment, N poles and S poles are arranged in 8 poles each, and a total of 16 poles are arranged at intervals of 22.5 °.

  The pair of yokes 31 and 32 are formed of a soft magnetic material in an annular shape, are fixed to the output shaft 12 outside the diameter of the multipolar magnet 14, and face each other with a gap in the axial direction. In each set of yokes 31 and 32, the same number of claws 33 and 34 as the N poles and S poles of the multipolar magnet 14 are provided at equal intervals along the inner edge of the ring. The claws 33 of one yoke 31 and the claws 34 of the other yoke 32 are alternately arranged with a shift in the circumferential direction. Thus, the pair of yokes 31 and 32 forms a magnetic circuit in the magnetic field generated by the multipolar magnet 14.

  When torsional displacement is applied to the torsion bar 13, the magnetic flux passing through the magnetic circuit changes with the relative rotation of the multipolar magnet 14 and the pair of yokes 31, 32, and information on the rotation angle is obtained by detecting the magnetic flux. can get. The detection principle is described in FIGS. 5 and 6 of Patent Document 1 (Japanese Patent Laid-Open No. 2012-237727).

  Since the torsion bar 13, the multipolar magnet 14, and the pair of yokes 31, 32 are configured coaxially, the central axis O may be defined based on any of them. In this specification, the yoke 31, 32 whose attention is paid to the opposing relationship with the magnetic flux guiding members 51, 52 is basically described as “the central axis O of the yokes 31, 32”.

  In the description of the embodiments, the axial direction and the radial direction of the torsion bar 13, the multipolar magnet 14, the pair of yokes 31, 32, and the like are simply referred to as “axial direction” and “radial direction”. Moreover, the plan view in the description of the drawings means a view seen from the first axis 11 side in the axial direction, and the side view means a view seen from the radial direction. “In plan view” is synonymous with “in axial projection”.

  The magnetic flux guiding members 51 and 52 are made of a soft magnetic material, and the main body 60 is opposed to at least one of the pair of yokes 31 and 32 in the axial direction or the radial direction. To 72. In many embodiments except the fourteenth embodiment, a set of magnetic flux guide members 51 and 52 are provided.

  Hereinafter, for convenience of explanation, the yoke 31 and the magnetic flux guiding member 51 arranged on the first shaft 11 side in FIGS. 1 and 2 are referred to as “upper yoke 31” and “upper magnetic flux guiding member 51”. The yoke 32 and the magnetic flux guiding member 52 arranged on the second shaft 12 side are referred to as “lower yoke 32” and “lower magnetic flux guiding member 52”. The upper magnetic flux guide member 51 faces the upper yoke 31, and the lower magnetic flux guide member 52 faces the lower yoke 32. In many embodiments except the thirteenth embodiment, the pair of yokes 31 and 32 are arranged symmetrically in the axial direction and face each other in the axial direction.

  As shown in FIG. 1, the set of magnetic flux guide members 511 and 521 of the first embodiment has two sets of extending contact portions 61 and 62 branched from the main body 60. Specifically, the extending contact portions 61 and 62 extend from the main body 60 to the outside in the radial direction of the yokes 31 and 32. The two magnetic sensors 71 and 72 are disposed between the extending contact portions 61 and 62, respectively. The extending contact portions 61 and 62 have a step in the axial direction so that the gap is minimized at the portion where the magnetic sensors 71 and 72 are disposed. For example, when the magnetic flux guide members 51 and 52 are press-molded, the steps of the extending contact portions 61 and 62 can be formed by bending a sheet metal or the like.

  The magnetic sensors 71 and 72 detect the magnetic flux induced by the magnetic flux guiding members 51 and 52 from the pair of yokes 31 and 32, convert it into a voltage signal, and output it to the external ECU 91 via the lead wires 73 and 74. To do. For example, the magnetic sensors 71 and 72 are configured by a substantially rectangular parallelepiped IC package in which a Hall element, a magnetoresistive element or the like is resin-molded.

  In the torque detection device having the above-described configuration, when the multipolar magnet 14 and the yokes 31 and 32 rotate in synchronization with the torque applied to the torsion bar 13 being constant, the magnetic flux passing through the magnetic circuit periodically varies. . The periodic fluctuation of the magnetic flux can become “swinging noise” with respect to the output signal from the magnetic sensors 71 and 72 to the ECU 91.

  Here, the whirling noise will be described with reference to FIG. 33 which is a reference diagram showing the flow of magnetic flux from the yoke claw to the ring. Depending on the distance from the claws 33 and 34 of the yokes 31 and 32 facing the multipolar magnet 14 that serves as a magnetic flux source, a difference in magnetic flux density occurs in the ring portions of the yokes 31 and 32. That is, the magnetic flux density is high in the portion close to the claws 33 and 34, and the magnetic flux density is small in the portion away from the claws 33 and 34.

  Therefore, when the multipolar magnet 14 and the yokes 31 and 32 rotate in synchronization, the magnetic sensor arranged at a specific position between the rings of the yokes 31 and 32 detects a change in magnetic flux accompanying the rotation. . Further, along with the rotation, leakage magnetic flux leaking from between the claws 33 and 34 is added, and the fluctuation of the magnetic flux increases. This is detected by the magnetic sensor as a whirling noise. As described above, when the whirling noise is relatively larger than the signal detected by the magnetic sensor, the S / N ratio is lowered.

  With respect to this noise, in the prior art of Patent Document 1, in the direction connecting the central axis O and the magnetic sensor, from the central axis O to the inner edge of the magnetism collecting ring (that is, the magnetic flux guiding member of the present embodiment). The shape of the magnetism collecting ring is determined so as to maximize the distance. For example, the magnetism collecting ring is formed in an elliptical arc shape having a major axis in the direction connecting the central axis O and the magnetic sensor. In this way, the magnetic sensor is kept away from the multipolar magnet to suppress the influence on the magnetic sensor due to the magnetic flux fluctuation.

  However, in the configuration of Patent Document 1, the axially facing area between the magnetic flux guiding member and the yoke is relatively small in the vicinity of the magnetic sensor, and depending on the embodiment, the facing area between the magnetic flux guiding member and the yoke is small. 0. For this reason, when the magnetic flux guide member and the yoke are opposed to each other at a portion away from the magnetic sensor and the magnetic flux is collected, the magnetic resistance is higher than when the magnetic flux is collected near the magnetic sensor, and the amount of magnetic flux collected by the sensor is reduced. Therefore, since the whirling noise is reduced and the signal is also reduced, there is a problem that improvement of the SN ratio cannot be expected.

  Therefore, this embodiment basically aims to improve the SN ratio of the magnetic flux detected by the magnetic sensor by suppressing the whirling noise while increasing the signal in the vicinity of the magnetic sensor. However, exceptionally, in the tenth embodiment, the S / N ratio is improved only by the noise suppressing effect without increasing the signal.

  In some embodiments, as a further object, the magnetic sensor module 50 is reduced in size and improved in assembly. For example, the semi-annular magnetism collecting ring disclosed in Patent Document 1 is easy to assemble in that it can be assembled from the radial direction as compared to an annular magnetism collecting ring that requires the torsion bar 13 and the multipolar magnet 14 to pass therethrough. Excellent. In some embodiments, not only can the assembly be performed from the radial direction, but also the magnetic sensor module 50 can be downsized to improve the manufacturing yield, reduce the space for component management, and further improve the assembly.

  Next, with reference to FIG. 3A to FIG. 22B, a detailed configuration of the magnetic sensor module 50 will be described for each embodiment. About the following 1st-9th embodiment, the code | symbol of a magnetic sensor module attaches the number of embodiment to the 3rd digit following "50", and the code | symbol of a set of magnetic flux induction members is "51", " The number of the embodiment is attached to the third digit following "52". In the tenth to fourteenth embodiments, the reference numerals of the magnetic sensor modules are “1” to “4” in the third digit following “55”. In addition, in the tenth to thirteenth embodiments, “0” to “3” are sequentially added to the third digit following “56” and “57” as a set of magnetic flux guiding members. About 14th Embodiment, the code | symbol of the magnetic flux induction member of only one side is set to "564."

  The configuration of the magnetic sensor module of each embodiment is shown in principle by three views: a plan view, a side view, and an axial sectional view. However, in the case where any of the figures is substantially the same as the above-described embodiment, the above-mentioned figure is used as appropriate. Further, in the specification, for example, “in a plan view” means “when a plan view is seen”. In the first embodiment, FIG. 3A is a plan view, FIG. 3B is a side view, and FIG. 4 is an axial sectional view. Strictly speaking, the “plan view” is a radial sectional view in which the multipole magnet 14 and the claws 33 and 34 of the yokes 31 and 32 are cut at the upper part of the upper magnetic flux guide member 51, but from the viewpoint of the magnetic flux guide member 51. Marked as “plan view”. Further, only the lower yoke 32 can actually see the ring in the radial sectional view, but for convenience of explanation, the reference numerals including the upper yoke 31 are denoted by “31, 32”.

  In each plan view, a “reference line X” extending in the left-right direction through the central axis O is described. 3A and the like, the reference line X is defined as an imaginary straight line connecting the intermediate position between the two magnetic sensors 71 and 72 and the central axis O. In other words, the two magnetic sensors 71 and 72 are arranged symmetrically with respect to the reference line X. In the diagram of the configuration including one magnetic sensor 71 such as FIG. 19, the reference line X is defined as an imaginary straight line connecting one magnetic sensor 71 and the central axis O. Each plan view is a neutral state in which no torsional displacement is applied to the torsion bar 13. In the neutral state, the center line of the magnetic pole (S pole in the example of FIG. 3A) coincides with the reference line X.

  The side view is a view of the magnetic sensor module 50 viewed from the outside in the radial direction along the reference line X. A two-dot chain line indicates the outer shape of the claws 33 and 34. In the side view, the torsion bar 13 and the multipolar magnet 14 are not shown. The axial sectional view is a sectional view in a plane including the central axis O and the reference line X. In the axial sectional view, the torsion bar 13 is not shown, and the multipolar magnet 14 shows only the outline.

(First embodiment)
The first embodiment will be described with reference to FIGS. 3A, 3B, and 4. FIG. In the magnetic sensor module 501 of the first embodiment, the main bodies of the magnetic flux guide members 511 and 521 are formed in a rectangular belt shape symmetrical with respect to the reference line X in plan view. The sides on the central axis O side of the magnetic flux guiding members 511 and 521 are straight lines orthogonal to the reference line X inside the yokes 31 and 32.

  The magnetic flux guiding members 511 and 521 have extending portions 61 and 62 extending radially outward from the main body 60, and “the branching portion of the main body 60 to the extending portions 61 and 62” is referred to as an S portion. The “branching portion to the extending contact portions 61 and 62” substantially means the vicinity of the magnetic sensors 71 and 72. The “S part” is the same symbol as the S pole of the multipolar magnet 14, but the distinction between them is obvious and there is no possibility of confusion.

  Further, with the reference line X in between, the portions corresponding to both ends in the circumferential direction of the yokes 31 and 32 in the range where the main body 60 and the yokes 31 and 32 of the magnetic flux guiding members 511 and 521 face each other are referred to as “the peripheral end portions 63 and 64 of the main body 60. And is indicated by broken line hatching in the figure. The circumferential end portions 63 and 64 are portions “corresponding” to “both ends in the circumferential direction in the facing range of the main body 60 and the yokes 31 and 32”, and the circumferential end portions 63 and 64 themselves face the yokes 31 and 32. It does not have to be included directly in the range. For example, the peripheral end portions 63 and 64 only need to correspond to “both ends in the circumferential direction in the direct facing range” outside the direct facing range, that is, on the side away from the reference line X. The distance ds from the S portion to the central axis O is shorter than the distance de from the peripheral end portions 63 and 64 to the central axis O.

  The magnetic flux guide members 511 and 521 face the annular surfaces of the yokes 31 and 32 with a constant gap on the inner side in the axial direction in a side view and an axial sectional view, and the facing areas are close to the magnetic sensors 71 and 72. It is relatively large at the intermediate portion 65 and decreases toward the peripheral end portions 63 and 64. In the S portion that is a branching portion to the extending portions 61 and 62, the facing area is larger than that of the peripheral end portions 63 and 64, and therefore, the magnetism per unit area between the magnetic flux guiding members 511 and 521 and the yokes 31 and 32. Permeance increases.

  Here, the meaning of “per unit area” is to clearly indicate that the area of the range in which magnetic permeance is compared is the same for each part. In the following description of the embodiment, the description of “per unit area” is omitted, and “magnetic permeance” is interpreted as meaning “magnetic permeance per unit area”.

  The two magnetic sensors 71 and 72 are disposed between the extending contact portions 61 and 62, respectively. The extended contact portions 61 and 62 are bent in the axial direction so that the gap is minimized at the portion where the magnetic sensors 71 and 72 are disposed, and have stepped portions. Such a configuration of the extending contact portions 61 and 62 is common to the following second to seventh and ninth to eleventh embodiments.

Next, with reference to FIG. 5A, FIG. 5B, and FIG. 6, the effect of the magnetic sensor module 50 of each embodiment except the tenth embodiment will be described. First, the reason why the signal becomes large will be described. FIG. 5A shows a correlation diagram between the distance from the reference line X or the rotation angle and the magnetic permeance with respect to the magnetic permeance between the magnetic flux guiding members 51 and 52 and the yokes 31 and 32. The magnetic permeance P is expressed by Equation (1) using the material permeability μ, the facing area A, and the gap length L.
P = μ (A / L) (1)

  Here, assuming that the magnetic flux guiding members 51 and 52 are formed of a single soft magnetic material, the larger the facing area A between the magnetic flux guiding members 51 and 52 and the yokes 31 and 32, or the gap length. The shorter L is, the larger the magnetic permeance P is.

  In the first embodiment and the like, the gap between the magnetic flux guiding members 51 and 52 and the yokes 31 and 32 is constant, but the facing area decreases as it goes from the intermediate portion 65 toward the peripheral end portions 63 and 64. On the other hand, in the third embodiment, which will be described later, the facing area between the magnetic flux guiding members 51 and 52 and the yokes 31 and 32 is constant, but the gap becomes larger from the intermediate portion 65 toward the peripheral end portions 63 and 64. Accordingly, in any of the embodiments, the magnetic permeance of the intermediate portion 65 is larger than the magnetic permeance of the peripheral end portions 63 and 64. In FIG. 5 (a), the correlation characteristic is any characteristic such as a straight line such as P1, a simple curve having no inflection point such as P2, an S-shaped curve such as P3, or a stepped broken line. There may be.

  Incidentally, Japanese Patent No. 5090162 and US Pat. No. 7,644,635 have a configuration in which “the magnetic permeance between the magnetic flux guiding member and the yoke is determined independently of the relative radius and angular position”. It is disclosed. This means that the magnetic permeance is constant regardless of the distance from the reference line X. This characteristic is shown by a broken line in FIG. 5A as a comparative example. The characteristic of this embodiment is clearly different from the characteristic of the comparative example in that the magnetic permeance changes according to the distance from the reference line X or the rotation angle.

  And in each embodiment except 10th Embodiment, the magnetic sensors 71 and 72 are installed in the extension part 61 and 62 branched from the main body 60 near the intermediate part 65 or the main body 60. FIG. Here, “installed” includes a form in which the magnetic sensors 71, 72 are arranged in a non-contact manner at positions close to the extended contact portions 61, 62, and the magnetic sensors 71, 72 are not necessarily connected to the extended portions 61, 72. Does not mean contacting 62. The installation site of the magnetic sensors 71 and 72 in the main body 60 of the magnetic flux guide members 51 and 52 or the branch site to the extending contact portions 61 and 62 substantially means “in the vicinity of the magnetic sensors 71 and 72”. The magnetic flux induction members 51 and 52 are installation portions of the magnetic sensors 71 and 72 in the main body 60 or branch portions to the extending contact portions 61 and 62, compared with the peripheral end portions 63 and 64. The magnetic permeance per unit area between the yoke 31 and the yoke 32 is increased. Thereby, the signal of the magnetic sensors 71 and 72 can be enlarged.

  Next, the reason why the whirling noise is reduced will be described. In the conventional torque detection device such as Patent Document 1, the shape of the magnetism collecting ring is formed in an annular shape, a semicircular shape, a semielliptical shape, or the like along the ring of the yoke. With these shapes, magnetic flux is collected from a wide area of the magnetic flux collecting ring to the magnetic sensor portion, so that the signal increases to some extent, and at the same time, magnetic flux fluctuations at each part are also collected. Variations occur. On the other hand, in each of the embodiments except for the tenth embodiment, the magnetic permeance between the yokes 31 and 32 and the magnetic flux guiding members 51 and 52 decreases at the peripheral ends 63 and 64 away from the magnetic sensors 71 and 72. It is configured.

  In FIG. 3A of the first embodiment, the magnetic flux flows between the yokes 31 and 32 and the magnetic flux guiding members 511 and 521, particularly at the S portion where the magnetic permeance is large. Then, the magnetic flux that has flowed into the magnetic flux guiding members 511 and 521 flows so as to leak and spread toward the peripheral end portions 63 and 64 as indicated by the broken line arrow B. This is because the magnetic flux density is low and the magnetic resistance is low at the peripheral end portions 63 and 64 of the magnetic flux guiding members 511 and 521, unlike the magnetic flux collecting ring of the conventional torque detecting device. Thereby, the fluctuation | variation of the magnetic flux which flows into the magnetic sensors 71 and 72 side through the extension parts 61 and 62 is suppressed, ie, the effect by which a magnetic flux is smoothed is produced.

  For example, in the neutral state in which the magnetic pole of the multipolar magnet 14 is between the claws 33 and 34 of the two yokes 31 and 32, that is, in the state where no torque is applied, the conventional magnetism collecting ring only collects the magnetic flux. , Large whirling noise occurs. On the other hand, since the magnetic flux guide members 511 and 521 of the first embodiment have a structure that suppresses fluctuations in the collected magnetic flux, fluctuations in the whirling noise are reduced as shown in FIG. In addition, in the configuration including the two magnetic sensors 71 and 72, the magnetic flux induced from the yokes 31 and 32 branches from the reference line X side toward the two magnetic sensors 71 and 72, and reaches the peripheral ends 63 and 64. It spreads toward you. This action can reduce the propagated whirling noise.

  It should be noted that the magnetic permeance between the magnetic flux guiding members 511 and 521 and the yokes 31 and 32 is also in the vicinity of the magnetic sensors 71 and 72 having the highest contribution to the amount of collected magnetic flux. Is increased and the magnetic flux is collected, so that the influence on the signal drop is small. From the above, in each of the embodiments except for the tenth embodiment, it is possible to suppress the whirling noise (N) while obtaining a large signal (S) as compared with the prior art. Therefore, the SN ratio of the magnetic flux detected by the magnetic sensors 71 and 72 can be improved.

  Next, with reference to FIG. 6, the production yield improvement by using the magnetic flux guide members 511 and 512 of the first embodiment will be described. For example, when punching out a sheet metal material with a press and taking two magnetic flux guide members 511 and 512, the main body 60 is arranged so that the extending portions 61 and 62 face each other, and laid out so that the unevenness is fitted to each other. Since the side opposite to the extending portions 61 and 62 is a straight line, the width of the material used to take the two magnetic flux guiding members 511 and 512 is W1.

  For comparison, arc-shaped magnetic flux guide members 513 and 523 in the third embodiment are indicated by two-dot chain lines. In this embodiment, it is necessary to use a material having a width W3 in order to take the two magnetic flux guide members 511 and 512, and the waste is large. On the other hand, in the first embodiment, material waste can be minimized and the manufacturing yield is improved. Further, since the magnetic flux guiding members 511 and 521 have a small width in the reference line X direction, they can be slid and assembled to the torque detection device 10 in the space of the width Win shown in FIG. . Therefore, for example, the assembling property can be further improved as compared with the case where a semi-annular magnetic flux guiding member is assembled.

(Second Embodiment)
About the magnetic sensor module 502 of 2nd Embodiment, the side view and axial direction sectional drawing use FIG.3 (b) and FIG.4 of 1st Embodiment. In the plan view of FIG. 7, the code | symbol of a magnetic flux guide member including a lower magnetic flux guide member is described as "512,522."

  As shown in FIG. 7, in the magnetic sensor module 502 of the second embodiment, the main bodies of the magnetic flux guiding members 512 and 522 are formed in a band shape having concentric arcs symmetrical with respect to the reference line X as opposite sides in plan view. Has been. This concentric arc is centered on a point Q located on the opposite side of the center axis O from the magnetic sensors 71 and 72 on the reference line X, and has a smaller curvature than the arc centered on the center axis O. Similarly to the first embodiment, the distance ds from the S portion that is a branching portion to the extending portions 61 and 62 in the main body 60 and the central axis O is greater than the distance de from the peripheral end portions 63 and 64 to the central axis O. Also short.

  The magnetic flux guiding members 512 and 522 are opposed to the yokes 31 and 32 with a certain gap on the inner side in the axial direction. The facing area is relatively large at the intermediate portion 65 close to the magnetic sensors 71 and 72 and decreases toward the peripheral end portions 63 and 64. Since the facing area at the branching portion to the extending portions 61 and 62 is larger than the peripheral end portions 63 and 64, the magnetic permeance between the magnetic flux guiding members 512 and 522 and the yokes 31 and 32 is increased. Therefore, 2nd Embodiment has an SN ratio improvement effect similarly to 1st Embodiment. The first embodiment in which the side on the central axis O side of the magnetic flux guiding member is a straight line is interpreted as a special form in which the point Q of the second embodiment exists at infinity and the curvature of the arc becomes infinitely small. The

(Third embodiment)
About the magnetic sensor module 503 of 3rd Embodiment, FIG. 4 of 1st Embodiment is used for axial direction sectional drawing. As shown in FIGS. 8A and 8B, in the magnetic sensor module 503 of the third embodiment, the main body of the magnetic flux guiding member 513 has a concentric arc centered on the central axis O in plan view. It is formed in the shape of a belt with the opposite side. The magnetic flux guiding members 513 and 523 face the yokes 31 and 32 on the inner side in the axial direction, and the facing areas are constant in the circumferential direction of the yokes 31 and 32.

  In the side view, the axial gap between the magnetic flux guiding members 513 and 523 and the yokes 31 and 32 ranges from the gap gc at the intermediate portion 65 close to the magnetic sensors 71 and 72 to the gap ge at the peripheral end portions 63 and 64. , It becomes larger toward the peripheral ends 63 and 64. Since the gap at the branching portion to the extending portions 61 and 62 is smaller than that of the peripheral end portions 63 and 64, the magnetic permeance between the magnetic flux guiding members 513 and 523 and the yokes 31 and 32 is increased. Therefore, 3rd Embodiment has an SN ratio improvement effect similarly to 1st Embodiment.

(Fourth embodiment)
As shown in FIGS. 9A, 9B, and 10, in the magnetic sensor module 504 of the fourth embodiment, the main body of the magnetic flux guiding members 514 and 524 is the outer shape of the yokes 31 and 32 in plan view. It is located in the outer side in the radial direction and is formed in a rectangular band shape symmetrical with respect to the reference line X. The sides on the central axis O side of the magnetic flux guiding members 514 and 524 are straight lines orthogonal to the reference line X. Therefore, the fourth embodiment has the effect of reducing the size and improving the yield, similar to the first embodiment.

  The magnetic flux guide members 514 and 524 face the side surfaces of the yokes 31 and 32 in the radial direction in a side view and an axial sectional view. The axial height of the facing portion is constant. The radial gap between the magnetic flux guiding members 514 and 524 and the yokes 31 and 32 increases from the intermediate portion 65 close to the magnetic sensors 71 and 72 toward the peripheral end portions 63 and 64. Since the gap at the branching portion to the extending portions 61 and 62 is smaller than the peripheral end portions 63 and 64, the magnetic permeance between the magnetic flux guiding members 514 and 524 and the yokes 31 and 32 is increased. Therefore, 4th Embodiment has an SN ratio improvement effect similarly to 1st Embodiment.

(Fifth and sixth embodiments)
11 and 12 are axial sectional views of the magnetic sensor modules 505 and 506 of the fifth and sixth embodiments. The fifth and sixth embodiments are other variations relating to the opposing configuration of the magnetic flux guiding member and the yoke. The main body of the magnetic flux guiding members 515, 525, 516, and 526 of the fifth and sixth embodiments has a rectangular band shape as in the first and fourth embodiments, or an arc as in the second embodiment. Any of the strips on opposite sides may be used.

  The magnetic flux guide members 511, 521 and the like of the first embodiment face the annular surfaces of the yokes 31, 32 on the inner side in the axial direction, whereas the magnetic flux guide members 515, 525 of the fifth embodiment are shown in FIG. Is arranged outside in the axial direction and faces the annular surface of the yokes 31, 32 on the outside in the axial direction. As shown in FIG. 12, the magnetic flux guide members 516 and 526 of the sixth embodiment face the annular surfaces and side surfaces of the yokes 31 and 32 in the axially outer side and the radial direction. As described above, the magnetic flux guide member of each embodiment may be disposed so as to face the yokes 31 and 32 in an axial direction, a radial direction, or a combination of both directions as appropriate.

(Seventh embodiment)
As shown in FIG. 13A, FIG. 13B, and FIG. 14, in the magnetic sensor module 507 of the seventh embodiment, the main bodies of the magnetic flux guiding members 517 and 527 are the yokes 31 and 32 in plan view. It is located in the outer side in the radial direction from the outer shape, and is formed in a belt shape having a concentric arc centered on the central axis O and opposite sides.

  A wall portion 35 that secures the height in the axial direction is formed at the periphery of the yokes 31 and 32 in a side view and a cross-sectional view in the axial direction. Instead of forming the wall portion 35, the thickness of the yokes 31 and 32 may be simply increased. The magnetic flux guiding members 517 and 527 are opposed to the side surfaces of the yokes 31 and 32 in the radial direction, and the radial gap is constant. Further, the axial heights of the main bodies of the magnetic flux guiding members 517 and 527 become smaller from the intermediate portion 65 near the magnetic sensors 71 and 72 toward the peripheral end portions 63 and 64. Therefore, the facing area between the magnetic flux guiding members 517 and 527 and the yokes 31 and 32 becomes smaller from the intermediate portion 65 toward the peripheral end portions 63 and 64. In the branch part (S part) to the extending parts 61 and 62, since the facing area is larger than the peripheral end parts 63 and 64, the magnetic permeance between the magnetic flux guiding members 517 and 527 and the yokes 31 and 32 is increased. . Therefore, 7th Embodiment has an SN ratio improvement effect similarly to 1st Embodiment.

(Eighth embodiment)
An axial sectional view of the magnetic sensor module 508 of the eighth embodiment is omitted. As shown in FIGS. 15A and 15B, in the magnetic sensor module 506 of the eighth embodiment, the magnetic flux guiding members 518 and 528 are configured only by a rectangular belt-shaped body, and the extending portions 61 and 62 are provided. I don't have it. In the magnetic flux guiding members 518 and 528, the magnetic sensors 71 and 72 are disposed between the sensor holding portions 66 and 67 bent so as to be close to each other in the axial direction. In this embodiment, the installation site of the magnetic sensors 71 and 72 in the main body 60 substantially corresponds to “the vicinity of the magnetic sensors 71 and 72”. The eighth embodiment has the effect of improving the SN ratio as in the first embodiment, and can further reduce the size of the magnetic sensor module 506.

(Ninth embodiment)
About the magnetic sensor module 509 of 9th Embodiment, a side view and axial direction sectional drawing are abbreviate | omitted. In the plan view of FIG. 16, the code | symbol of a magnetic flux guidance member is described as "519,529" including a lower magnetic flux guidance member. As shown in FIG. 16, in the magnetic sensor module 509 of the ninth embodiment, the magnetic flux guiding members 519 and 529 are formed separately on one side and the other side of the reference line X, respectively. In other respects, the ninth embodiment is the same as the first embodiment. In the ninth embodiment, in addition to the effects of the first embodiment, the manufacturing yield of the magnetic flux guiding member can be further improved by omitting the intermediate portion 65. In the ninth embodiment, it is assumed that two magnetic sensors 71 and 72 or an even number of four or more magnetic sensors are arranged symmetrically with respect to the reference line X.

(10th Embodiment)
About the magnetic sensor module 510 of 10th Embodiment, FIG. 4 of 1st Embodiment is used for axial sectional drawing. As shown in FIGS. 17A and 17B, in the magnetic sensor module 550 of the tenth embodiment, the magnetic flux guiding members 560 and 570 are extended with respect to the magnetic flux guiding members 511 and 521 of the first embodiment. The difference is that the installation portions 61 and 62 are provided near the peripheral end portions 63 and 64. That is, in the tenth embodiment, the facing area between the magnetic flux guide members 560 and 570 and the yokes 31 and 32 at the S portion that is a branching portion to the extending contact portions 61 and 62 is smaller than that of the intermediate portion 65. . Note that the extended contact portion may not be provided as in the eighth embodiment, and the magnetic sensors 71 and 72 may be directly installed on the main body 60.

  As shown in FIG. 18 corresponding to FIG. 5A, in the tenth embodiment, in the correlation diagram between the distance from the reference line X or the rotation angle and the magnetic permeance, the magnetic sensors 71 and 72 have the peripheral end 63. , 64. Therefore, the magnetic flux guiding members 560 and 570 of the tenth embodiment are S portions that are branched portions to the extending contact portions 61 and 62 in the main body 60, and compared with the portions on the reference line X, the magnetic flux guiding members 560 and 570 Magnetic permeance between the yokes 31 and 32 is configured to be small. Further, “the magnetic permeance between the magnetic flux guiding member and the yoke is determined independently of the relative radius and the angular position”, that is, in the comparative example in which the magnetic permeance is constant regardless of the distance from the reference line X. The tenth embodiment is common to the first embodiment in that it is different from the characteristics.

  From the viewpoint of improving the S / N ratio, the tenth embodiment does not have the effect of increasing the signal as in the first embodiment. However, the magnetic flux induced from the yokes 31 and 32 branches from the reference line X side toward the two magnetic sensors 71 and 72 as indicated by the broken line arrow M. Thereby, the propagating noise can be reduced. Therefore, also in the tenth embodiment, the SN ratio of the magnetic flux detected by the magnetic sensors 71 and 72 is improved. Due to such characteristics, the tenth embodiment is premised on a configuration in which two or more even number of magnetic sensors are arranged symmetrically with respect to the reference line X, similarly to the ninth embodiment.

(11th and 12th embodiments)
In contrast to the first to tenth embodiments provided with two magnetic sensors 71 and 72, the magnetic sensor module may be configured such that one magnetic sensor is disposed on the reference line X. Here, embodiments in which the number of magnetic sensors is changed to one in the first and eighth embodiments will be described as eleventh and twelfth embodiments.

  About the magnetic sensor module 551 of 11th Embodiment, a side view and axial direction sectional drawing are abbreviate | omitted. In the plan view of FIG. 19, the reference numerals of the magnetic flux guiding members including the lower magnetic flux guiding member are denoted as “561, 571”. As shown in FIG. 19, the magnetic flux guiding members 561 and 571 are different from the magnetic flux guiding members 511 and 521 of the first embodiment in that one extending portion 61 corresponding to one magnetic sensor 71 is formed. .

  A side view and an axial cross-sectional view of the magnetic sensor module 552 of the twelfth embodiment are omitted. In the plan view of FIG. 20, the reference numerals of the magnetic flux guiding members including the lower magnetic flux guiding member are indicated as “562, 572”. As shown in FIG. 20, the magnetic flux guiding members 562 and 572 are different from the magnetic flux guiding members 518 and 528 of the eighth embodiment in that one sensor holding portion 66 corresponding to one magnetic sensor 71 is formed. .

  As described above, the number of magnetic sensors applied to the magnetic sensor module of each embodiment is one or two except for the ninth and tenth embodiments based on the assumption that the two magnetic sensors 71 and 72 are provided. Or three or more. Specifically, the number of extending portions of the magnetic flux guiding member or the number of sensor holding portions may be adjusted according to the number of applied magnetic sensors.

(13th Embodiment)
In any of the above-described embodiments, the magnetic sensors 71 and 72 are arranged so that the wide surface of the substantially rectangular parallelepiped IC package is orthogonal to the axis (so-called lateral orientation). On the other hand, the magnetic sensor module 553 of the thirteenth embodiment shown in FIGS. 21A and 21B is arranged so that the wide surface of the substantially rectangular parallelepiped IC package is parallel to the axis (so-called vertical orientation). Is done. In FIG. 21A, the symbols of the peripheral end portions 63 and 64 and the description of hatching are omitted.

  For example, the main bodies of the magnetic flux guiding members 563 and 573 are positioned in the radial direction outside the outer shape of the yokes 31 and 32 in a plan view, and are symmetrical with respect to the reference line X, as in the fourth embodiment. The yokes 31 and 32 are opposed to each other in the radial direction. An extending portion 611 that bends downward from the upper magnetic flux guide member 563 holds the radially outer side of the magnetic sensor 71. An extending portion 612 that bends upward from the lower magnetic flux guiding member 573 holds the radially inner side of the magnetic sensor 71. The thirteenth embodiment is effective, for example, when the lead wire 73 is to be taken out in the axial direction. Note that the thirteenth embodiment can also be applied to a configuration with one magnetic sensor.

(14th Embodiment)
In any of the above-described embodiments, a set of magnetic flux guide members facing each of the set of yokes is provided. On the other hand, in the magnetic sensor module 554 of the fourteenth embodiment shown in FIGS. 22A and 22B, the magnetic flux guiding member is provided only on one yoke side and not on the other yoke side. . For example, the magnetic flux guiding member 564 is disposed between the pair of yokes 31 and 32 in the axial direction, and the upper end portion faces the upper yoke 31. The magnetic sensor 71 is disposed between the lower end portion of the magnetic flux guiding member 564 and the lower yoke 32. That is, magnetic flux is directly transmitted from the lower yoke 32 to the lower surface of the magnetic sensor 71 without passing through the magnetic flux guiding member. Thus, a set of magnetic flux guide members may not necessarily be provided so as to face each of the set of yokes. The fourteenth embodiment can also be applied to a configuration with one magnetic sensor.

[Relationship between main body length of magnetic flux induction member and whirling noise]
In the description with reference to FIG. 5B described above, the magnetic flux that has flowed into the magnetic flux guiding members 511 and 521 flows so as to spread from the intermediate portion 65 toward the peripheral end portions 63 and 64, thereby causing vibration noise. Explained the reduction. Next, the condition of the main body length of the magnetic flux guiding member that optimizes the reduction of the whirling noise will be described with reference to FIGS. First, the number of magnetic poles of the multipolar magnet 14 is assumed to be 16 poles. Here, the number of magnetic poles of the multipolar magnet 14 is such that the two magnetic sensors 71 and 72 are provided and the extending portions 61 and 62 are provided near the intermediate portion 65 of the main body 60 of the magnetic flux guiding members 51 and 52. The optimum condition for the length of the main body 60 is examined.

  As the shape of the main body 60 of the magnetic flux guiding members 51 and 52, “the rectangular belt-shaped magnetic flux guiding members 511 and 521 whose longitudinal sides are orthogonal to the reference line X” of the first embodiment, and “ A strip-shaped magnetic flux guide member 513, 523 "having a concentric arc as an opposite side is assumed. In any case, the main body 60 is arranged symmetrically with respect to the reference line X. Hereinafter, the shape of the magnetic flux guiding members 511 and 521 of the first embodiment is simply expressed as “linear”, and the shape of the magnetic flux guiding members 513 and 523 of the third embodiment is simply expressed as “arc”.

  FIG. 23 is a plan view corresponding to FIG. 3A of the first embodiment. Here, in the axial projection of the yokes 31 and 32, the section is defined by two straight lines OM1 and OM2 that connect the central axis O of the multipolar magnet 14 and the arbitrary points M1 and M2 of the peripheral ends 63 and 64. The range in the circumferential direction is defined as “magnetic flux radiation range”. In FIG. 23, the S pole on the reference line X on the magnetic flux guiding members 511 and 521 side is called “reference magnetic pole”, and the two N poles adjacent to both sides of the reference magnetic pole are called “reference adjacent magnetic poles”. In the example shown in FIG. 23, the straight lines OM1 and OM2 pass through the center of the reference adjacent magnetic pole. Therefore, the number of magnetic poles of the multipolar magnet 14 included in the magnetic flux radiation range is two. In the figure, the straight lines OM1 and OM2 are represented by horizontal bars on “OM1” and “OM2”.

  Thus, the length of the linear magnetic flux guiding members 511 and 521 in the direction perpendicular to the reference line X of the main body 60 is defined as “the number of magnetic poles of a multipolar magnet included in the magnetic flux radiation range” (hereinafter referred to as “the number of magnetic poles in the radiation range”). ]). FIG. 24 shows the relationship between the number of radiating range magnetic poles and swing noise obtained by simulation. The whirling noise decreases as the number of radiating range poles increases from one pole, decreases to about 2.0 poles, and increases as the number increases from 2 poles to 3 poles.

  When the allowable threshold value for the whirling noise is set to Th1, the whirling noise falls below the allowable threshold value Th1 when the number of radiation range magnetic poles is in the range of 1.2 poles to 2.8 poles. Therefore, the length of the main body 60 of the magnetic flux guiding members 511 and 521 is preferably set so that the number of radiation range magnetic poles is included in the range of 1.2 poles to 2.8 poles.

  Further, when the allowable threshold value for the whirling noise is set to Th2 lower than Th1, the whirling noise falls below the allowable threshold value Th2 when the number of radiation range magnetic poles is in the range of 1.5 poles to 2.5 poles. Therefore, in the range where the number of radiation range magnetic poles is 1.5 poles to 2.5 poles, the effect of reducing the whirling noise becomes larger. In particular, when the number of radiation range magnetic poles is 2.0, the effect of reducing whirling noise is maximized.

  FIG. 25 is a plan view corresponding to FIG. 8A of the third embodiment. The terminology and the notation shown in FIG. In the example shown in FIG. 25, as in FIG. 23, the straight lines OM1 and OM2 pass through the center of the reference adjacent magnetic pole, and the number of magnetic poles of the multipolar magnet 14 included in the magnetic flux radiation range is two. In addition, the circumferential length of the main body 60 of the arc-shaped magnetic flux guide members 513 and 523 is expressed by the number of radial range magnetic poles, and the relationship between the number of radial range magnetic poles and the run-out noise obtained by simulation is shown in FIG. .

  The whirling noise becomes maximum when the number of radiation range magnetic poles is 2.5 or more, and monotonously decreases as the number of radiation range magnetic poles decreases when the number of radiation range magnetic poles is less than 2.5. Therefore, it is preferable that the circumferential length of the main body 60 of the magnetic flux guiding members 513 and 523 is set so that the number of radiation range magnetic poles is less than 2.5.

  Next, FIGS. 27A and 27B show the simulation results of the linear magnetic flux guiding members 511 and 521 when the number of magnetic poles of the multipolar magnet is other than 16. As shown in FIG. 27 (a), when the number of magnetic poles of a multipolar magnet is 12, the whirling noise is reduced when the number of radiation range magnetic poles indicated by a broken line is about 2.0 or more. However, this is because the distance between the magnetic flux guiding members 511 and 521 and the yokes 31 and 32 is increased and the magnetic flux is not affected. On the other hand, when the number of radiation range magnetic poles is in the range of 1.5 poles to 2.0 poles, the tendency that the whirling noise rapidly decreases as the number of radiation range magnetic poles increases is consistent with the case of 16 poles.

  In addition, as shown in FIG. 27B, when the number of magnetic poles of the multipolar magnet is 20, the range in which the number of radiation range magnetic poles is 2.5 poles or less on the assumption that the magnetic sensors 71 and 72 of the same size are used. Thus, the shapes of the magnetic flux guiding members 511 and 521 are not established. However, assuming that a magnetic sensor having a smaller size is used, as shown by the broken line, in the range where the number of magnetic poles in the radiation range is 2.0 to 2.5, the radiation is the same as in the case of 16 magnetic poles. It is considered that the whirling noise decreases as the number of range magnetic poles approaches 2.0.

  Therefore, the number of magnetic poles of the multipolar magnet is not limited to 16, but the length of the main body 60 of the linear magnetic flux guiding members 511 and 521 is 1.5 in the radiation range even when the number is 12 or 20 poles. It is preferable to be included in the range of ˜2.5 poles.

(Other embodiments)
(A) In the first embodiment, the main body 60 of the magnetic flux guiding members 511 and 521 is formed in a rectangular strip shape symmetrical with respect to the reference line X in plan view. In addition, in FIG. 3 and the like, the “rectangular band” is ideally illustrated as a shape having four straight lines. However, the rectangular strip shape may be any shape as long as the overall appearance is substantially rectangular.

  For example, a magnetic flux guiding member 565A of the magnetic sensor module 555A shown in FIG. 28A has a V-shaped cut recessed toward the reference line X on the short sides constituting the peripheral ends 63 and 64 of the main body 60. A magnetic flux guiding member 565B of the magnetic sensor module 555B shown in FIG. 28B is formed in a trapezoidal shape in which the long sides on the extending contact portions 61 and 62 side of the main body 60 are shorter than the long sides on the central axis O side of the yokes 31 and 32. Has been.

  On the other hand, the magnetic flux guiding member 565C of the magnetic sensor module 555C shown in FIG. 29 (a) has a longer side on the extending contact portions 61 and 62 side of the main body 60 than the long side on the central axis O side of the yokes 31 and 32. It is formed into a shape. The magnetic flux guiding member 565D of the magnetic sensor module 555D shown in FIG. 29B is arranged along the reference line X toward the extending portions 61 and 62 on the long side of the yokes 31 and 32 of the main body 60 on the central axis O side. A concave V-shaped cut is formed.

  In addition, a shape in which a substantially rectangular long side of the main body 60 is formed in a wave shape like the magnetic flux guide member 566 of the magnetic sensor module 556 shown in FIG. 30 is interpreted as being included in the “rectangular band shape”. The number of waves and the size of the unevenness are not limited to the illustrated example, and the shape of the waves may be triangular or sawtooth. In the first place, in reality, the surface that looks straight with the naked eye is considered to be a wavy surface microscopically. Similarly, in the arc-shaped main body as in the third embodiment, the opposite sides of the arc may be formed in a wave shape.

  (B) The magnetic flux guiding members 512 and 513 of the second and third embodiments have the main body 60 formed in an arc shape, whereas the magnetic flux guiding member 567 of the magnetic sensor module 557 shown in FIG. In addition, the main body 60 may be formed in a shape that forms a part of a polygon. In the example shown in FIG. 31, the main body 60 is constituted by three linear portions in which both ends of the main linear portion are bent inward in the radial direction, but in other examples, two V-shaped linear portions or four You may make it the main body 60 be comprised from the above linear part.

  (C) In FIG. 1 and the like of the above-described embodiment, the pair of yokes 31 and 32 are annular with a constant width, and the claws 33 and 34 are formed so as to be bent in the axial direction from the inner periphery of the yokes 31 and 32. Yes. On the other hand, in the pair of yokes 36 and 37 shown in FIGS. 32A and 32B, the inside of the ring is cut out at the portion between the adjacent claws 38 and 39, and the width of the ring is narrow. It has become. In other words, the claws 38 and 39 are formed so as to bend in the axial direction after projecting radially inward from the ring. Thereby, the area of the magnetic circuit of the claws 38 and 39 can be enlarged, and the magnetic flux collected in the yokes 36 and 37 can be increased.

  (D) On the premise that the magnetic flux guide members 51 and 52 of the above embodiment are formed of a single soft magnetic material, the magnetic permeance depending on the part is changed depending on the facing area or gap difference from the yokes 31 and 32. ing. In addition, according to the formula (1), it is theoretically possible to change the magnetic permeance depending on the portion by bonding the two or more kinds of materials having different magnetic permeability μ to form the magnetic flux guiding member.

  (E) In the above embodiment, the multipolar magnet 14 is fixed to the input shaft 11 and the pair of yokes 31 and 32 is fixed to the output shaft 12. The yokes 31 and 32 may be fixed to the input shaft 11. Further, the multipolar magnet 14 may be fixed to one end side of the torsion bar 13 and the pair of yokes 31 and 32 may be fixed to the other end side of the torsion bar 13.

  (F) The torque detection device of the present invention can be applied not only to an electric power steering device but also to various devices that detect shaft torque.

  As mentioned above, this invention is not limited to such embodiment, In the range which does not deviate from the meaning, it can implement with a various form.

10: Torque detection device,
11 ... Input shaft (first axis), 12 ... Output shaft (second axis),
13 ... Torsion bar, 14 ... Multipole magnet,
31, 32 ... a set of yokes,
50 (501-509, 550-557) ... magnetic sensor module,
51 (511-519, 560-567), 52 (521-529, 570-573)
... Magnetic flux induction members,
60 ... main body 61, 62 ... extension part, 63, 64 ... peripheral edge part,
71, 72: Magnetic sensor, X: Reference line.

Claims (14)

A torsion bar (13) for connecting a first shaft (11) and a second shaft (12) coaxially, and converting a torque applied between the first shaft and the second shaft into a torsional displacement;
A multipolar magnet (14) fixed to one end side of the first shaft or the torsion bar and having N and S poles alternately arranged in the circumferential direction;
Formed with soft magnetic material, fixed to the second shaft or the other end of the torsion bar outside the diameter of the multipole magnet, facing each other in the axial direction, and forming a magnetic circuit in the magnetic field of the multipole magnet A set of yokes (31, 32)
One or more magnetic flux induction members (51, 52) that are formed of a soft magnetic material, and at least one of the yoke and the main body (60) face each other and induce magnetic flux of the magnetic circuit;
One or more magnetic sensors (71, 72) that are installed in the main body of the magnetic flux guide member or the extended contact portions (61, 62) branched from the main body and detect the magnetic flux induced by the magnetic flux guide member; ,
With
In the axial projection of the yoke,
When there is a single magnetic sensor, the magnetic sensor and the central axis of the yoke are connected. When there are a plurality of magnetic sensors, a virtual straight line connecting the intermediate position of the magnetic sensors and the central axis of the yoke is used as a reference. Line (X)
When the portions corresponding to both ends in the circumferential direction of the yoke in the facing range between the main body of the magnetic flux guiding member and the yoke are defined as the peripheral end portions (63, 64) of the main body of the magnetic flux guiding member, with the reference line interposed therebetween,
The magnetic flux guide member is a part of the main body where the magnetic sensor is installed or branched to the extension part, and has a magnetic permeance per unit area between the magnetic flux guide member and the yoke as compared with the peripheral end. A torque detector configured to be large.   The distance from the installation site of the magnetic sensor in the main body of the magnetic flux guide member or the branch site to the extension part to the central axis of the yoke is shorter than the distance from the peripheral end to the central axis of the yoke. Item 2. The torque detection device according to Item 1. In the axial projection of the yoke,
The torque detecting device according to claim 2, wherein the magnetic flux guiding member has a straight side on the central axis side of the yoke. In the axial projection of the yoke,
The torque detection device according to claim 3, wherein the magnetic flux guiding member is a straight line whose side on the central axis side of the yoke is orthogonal to the reference line.   The torque detection device according to claim 1, further comprising two magnetic sensors arranged symmetrically with respect to the reference line.   The torque detection device according to any one of claims 1 to 5, wherein the magnetic flux guiding member is opposed to the yoke at least in an axial direction of the yoke.   The torque detection device according to any one of claims 1 to 6, wherein the magnetic flux guiding member faces the yoke at least in a radial direction of the yoke.   The torque detection device according to any one of claims 1 to 7, further comprising a set of the magnetic flux guide members facing each of the set of yokes. Each of the magnetic flux guiding members has the extending contact portion extending from the main body to the radially outer side of the yoke,
The torque detection device according to claim 8, wherein the magnetic sensor is disposed between the extended contact portions of the pair of magnetic flux guide members.   The extended contact portion of the set of magnetic flux guide members has a step in the axial direction of the yoke so that a gap is minimized at a portion where the magnetic sensor is disposed. Torque detection device. In the axial projection of the yoke,
The main body of the magnetic flux guiding member is disposed symmetrically with respect to the reference line, and has a rectangular band shape whose longitudinal sides are orthogonal to the reference line,
When the circumferential range defined by two straight lines connecting the central axis of the multipolar magnet and the peripheral end portions on both sides of the main body of the magnetic flux guiding member is defined as a magnetic flux radiation range, it is included in the magnetic flux radiation range. The torque detection device according to claim 9 or 10, wherein the number of magnetic poles of the multipolar magnet is included in a range of 1.2 to 2.8 poles. In the axial projection of the yoke,
The main body of the magnetic flux guide member is arranged in a symmetric manner with respect to the reference line, and has a strip shape with concentric arcs extending in the circumferential direction along the yoke as opposite sides,
When the circumferential range defined by two straight lines connecting the central axis of the multipolar magnet and the peripheral end portions on both sides of the main body of the magnetic flux guiding member is defined as a magnetic flux radiation range, it is included in the magnetic flux radiation range. The torque detection device according to claim 9 or 10, wherein the number of magnetic poles of the multipolar magnet is less than 2.5 poles. It is used for the torque detection device according to any one of claims 1 to 12,
A magnetic sensor module in which the magnetic flux guiding member and the magnetic sensor are integrally formed. A torsion bar (13) for connecting a first shaft (11) and a second shaft (12) coaxially, and converting a torque applied between the first shaft and the second shaft into a torsional displacement;
A multipolar magnet (14) fixed to one end side of the first shaft or the torsion bar and having N and S poles alternately arranged in the circumferential direction;
Formed with soft magnetic material, fixed to the second shaft or the other end of the torsion bar outside the diameter of the multipole magnet, facing each other in the axial direction, and forming a magnetic circuit in the magnetic field of the multipole magnet A set of yokes (31, 32)
One or more magnetic flux induction members (560, 570) formed of a soft magnetic material, wherein at least one of the yoke and the main body (60) is opposed to induce magnetic flux of the magnetic circuit;
Two magnetic sensors (71, 72) that are installed in the main body of the magnetic flux guiding member or the extending contact portions (61, 62) branched from the main body and detect the magnetic flux induced by the magnetic flux guiding member;
With
In the axial projection of the yoke,
When there is a single magnetic sensor, the magnetic sensor and the central axis of the yoke are connected. When there are a plurality of magnetic sensors, a virtual straight line connecting the intermediate position of the magnetic sensors and the central axis of the yoke is used as a reference. Assuming line (X)
The magnetic flux guide member is a straight line in which the side on the central axis side of the yoke is orthogonal to the reference line,
The two magnetic sensors are arranged symmetrically with respect to the reference line,
The magnetic flux guiding member is a magnetic permeance per unit area between the magnetic flux guiding member and the yoke, compared with a portion on the reference line, at a portion where the magnetic sensor is installed in the main body or a branching portion to the extending contact portion. Torque detection device configured to be small.

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