JP2009128181A - Torque detector, electric power steering apparatus, and claw pole manufacturing method - Google Patents

Abstract

Provided is a torque detector that can be reduced in size, has a good manufacturing yield, and can be reduced in cost.
In a torque detector, a sensor yoke is disposed so as to be opposed to the axial direction of a permanent magnet. The sensor yoke 30 includes a first sensor yoke portion 30a on the inner side in the radial direction and a second sensor yoke portion 30b on the outer side in the radial direction, each having a plurality of claw poles arranged annularly in the circumferential direction. The claw poles 50 of the yoke part 30a and the claw poles 51 of the second sensor yoke part 30b are alternately arranged on the same circumference or substantially the same circumference, and the radially inner ends of the claw poles 50 are adjacent to each other. The claw pole 51 extends in the circumferential direction to the inner periphery of the radially inner end, and the radially outer end of the claw pole 51 extends in the circumferential direction to the outer periphery of the radially outer end of the adjacent claw poles 50. Yes.
[Selection] Figure 3

Description

  The present invention relates to a torque detector (torque sensor), an electric power steering device (EPS), and a claw pole manufacturing method included in the torque detector.

  For example, an electric power steering device is equipped with a torque detector that detects the steering torque of the steering wheel in order to add an appropriate auxiliary steering torque. Conventionally, the torque detectors described in Patent Documents 1 and 2 are known. The torque detector described in Patent Document 1 is provided with a pair of ring-shaped sensor members so as to face the outer peripheral side of a ring-shaped permanent magnet that is multipolarly magnetized along the circumferential direction. Torque generated on the permanent magnet side or on the sensor member side is detected based on the magnetic flux detected by a magnetic flux detector (magnetic sensor) disposed therebetween. The torque detector disclosed in Patent Document 2 is a pair of ferromagnetic fluxes having a plurality of teeth so as to face a ring-shaped magnetic pole wheel (permanent magnet) magnetized in the circumferential direction. A ring is provided, and the torque generated on the permanent magnet side or the flux ring side is detected based on the magnetic flux detected by the magnetic sensor arranged between these flux rings.

Japanese Patent No. 3874642 International Publication No. 2007/003468 Pamphlet

  However, in the torque detector described in Patent Document 1, in order to detect torque based on the output of the magnetic flux detector, the sensor member needs to receive a certain amount of magnetic flux generated by the permanent magnet. And the area where the permanent magnets face each other had to be increased.

  For this reason, in the torque detector described in Patent Document 1, the axial dimensions of the sensor member and the permanent magnet must be lengthened. As a result, the torque detector itself and the electric power provided with the torque detector are included. It is difficult to miniaturize the steering device.

  Further, in the torque detector described in Patent Document 2, since the permanent magnet and the flux ring face each other in the axial direction, there is no problem as in the technique of Patent Document 1 described above, but the flux having a complicated structure. In manufacturing the ring, the yield is poor and it is difficult to reduce the cost.

  The present invention has been made in view of the above points, and can provide a torque detector and an electric power steering device that can be reduced in size by reducing the size in the axial direction, can be manufactured at a good yield, and can be reduced in cost. Another object of the present invention is to provide a method of manufacturing a claw pole of the torque detector.

  In order to achieve the above object, the present invention provides a first shaft and a second shaft that are coaxially connected via a connecting shaft, and is fixed to one end of the first shaft or the connecting shaft in the circumferential direction. An annular permanent magnet magnetized along multiple poles, a sensor yoke fixed to the other end of the second shaft or the connecting shaft and forming a magnetic circuit with the permanent magnet, and disposed opposite to the sensor yoke A magnetic flux collecting yoke that induces magnetic flux from the sensor yoke and forms the magnetic circuit together with the permanent magnet and the sensor yoke, and a magnetic flux detector that detects the magnetic flux induced by the magnetic flux collecting yoke, A torque detector that detects torque applied to one of the first axis and the second axis based on an output of the magnetic flux detector, wherein the sensor yoke is in an axial direction of the permanent magnet Arranged opposite the The yoke has a first sensor yoke portion on the radially inner side and a second sensor yoke portion on the radially outer side having a plurality of claw poles arranged annularly in the circumferential direction. The claw poles and the claw poles of the second sensor yoke part are alternately arranged on the same circumference or substantially the same circumference, and the radially inner ends of the claw poles of the first sensor yoke part are adjacent to each other. The second sensor yoke portion is extended in the circumferential direction to the inner periphery of the radially inner end portion of the claw pole, and the radially outer end portion of the claw pole of the second sensor yoke portion is adjacent to the first sensor on both sides. The yoke portion is characterized by extending in the circumferential direction to the outer periphery of the radially outer end portion of the claw pole of the yoke portion.

  According to the present invention, since the sensor yoke is disposed opposite to the axial direction of the permanent magnet, the axial length of the permanent magnet or the sensor yoke can be shortened even if the opposing area of the sensor yoke and the permanent magnet is increased. As a result, the axial dimension of the entire torque detector can be shortened, and the sensor detector can be miniaturized. In addition, since the sensor yoke is configured using a claw pole, it is easy to manufacture, and as a result, the yield at the time of manufacturing is improved and the cost is reduced. Further, since the claw pole of the first sensor yoke portion and the claw pole of the second sensor yoke portion extend in the circumferential direction, even when the claw pole is used, for example, the facing area between the magnetism collecting yoke and the sensor yoke As a result, high permeance is secured between the magnetism collecting yoke and the sensor yoke, and the torque can be detected with high accuracy.

  The extending portions of the adjacent claw poles of the first sensor yoke portion extend to the vicinity of the center of the radially inner end of the claw pole of the second sensor yoke portion therebetween, and are close to each other. The extending portions of the adjacent claw poles of the yoke portion may extend to the vicinity of the center of the radially outer end portion of the claw pole of the first sensor yoke portion therebetween, and may be close to each other. In such a case, for example, the opposing area between the magnetism collecting yoke and the sensor yoke is further increased, the permeance between the magnetism collecting yoke and the sensor yoke can be improved, and the torque detection accuracy can be improved.

  The claw pole has a rectangular and flat main body part, and an extending part extending in the circumferential direction from a radial end of the main body part, and an internal angle of a connection part between the main body part and the extending part R processing may be given to. When the connecting portion between the claw pole body and the extending portion has an acute angle, the magnetic flux tends to concentrate on that portion, and magnetic saturation is likely to occur. According to the present invention, the inner corner of the connecting portion between the claw pole body and the extending portion is subjected to R processing, so that magnetic flux is concentrated on the connecting portion to prevent magnetic saturation, resulting in torque. The linearity between the rotation angle and the magnetic flux density in the detector is improved, and the torque detection accuracy is improved.

  The magnetism collecting yoke may be disposed opposite to the axial side of the sensor yoke.

  The magnetism collecting yoke may be arranged to face the radial side of the sensor yoke. In this case, since the axial dimension of the entire torque detector can be shortened by the amount of the magnetic collecting yoke, the sensor detector can be further reduced in size.

  The magnetism collecting yokes may be arranged on the inner side and the outer side in the radial direction of the sensor yoke, and each may be formed in a cylindrical shape having a width in the axial direction.

  According to another aspect of the present invention, the electric power that generates auxiliary steering torque from the electric motor in response to the steering torque applied to the steering wheel, decelerates by the speed reducer, and transmits it to the output shaft of the steering mechanism. In the steering apparatus, an electric power steering apparatus including any one of the above torque detectors is provided. Thereby, size reduction and performance improvement of an electric power steering device can be achieved.

  According to another aspect of the present invention, there is provided a method of manufacturing a claw pole included in the torque detector, wherein a plurality of claw poles are formed in a row so as to be alternately switched by punching. According to this manufacturing method, the material efficiency can be dramatically improved.

  According to the present invention, the torque detector and the electric power steering using the torque detector can be reduced in size, and the manufacturing yield can be increased to reduce the cost.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. FIG. 1 is an explanatory view of a longitudinal section showing an outline of the configuration of the torque detector 1 according to the present embodiment. FIG. 2 is a perspective view showing an outline of a main configuration of the torque detector 1. The torque detector 1 is used in an electric power steering device that generates auxiliary steering torque by an electric motor, for example, corresponding to the steering torque applied to the steering wheel, decelerates by a speed reducer, and transmits it to the output shaft of the steering mechanism. It is what

  As shown in FIG. 1, the torque detector 1 includes a first shaft 11 and a second shaft 12 connected by a torsion bar (connection shaft) 10 that is a torsion element. The 1st axis | shaft 11 and the 2nd axis | shaft 12 are comprised by the column shape, These center axis | shafts and the center axis | shaft of the torsion bar 10 are extended on the straight line.

  An annular permanent magnet 20 that is multipolarly magnetized in the circumferential direction is fixed to the first shaft 11 via a back yoke 21. As shown in FIG. 3, the permanent magnet 20 is alternately magnetized with N and S poles at predetermined angular intervals along the circumferential direction. In the present embodiment, for example, the N pole and the S pole are magnetized on the permanent magnet 20 at intervals of 22.5 [°]. Therefore, the permanent magnet 20 has a total of 16 poles. In addition, as a magnet material which comprises the permanent magnet 20, a ferrite magnet, a rare earth magnet, a metal magnet, a sintered magnet, a plastic magnet, a rubber magnet, etc. can be used.

  As shown in FIG. 1, an annular sensor yoke 30 that receives a magnetic flux from the permanent magnet 20 as shown in FIG. 1 is attached to the second shaft 12 in a state of being molded with a resin 31 that is a molding material. The sensor yoke 30 is attached so as to face one side of the permanent magnet 20 in the axial direction. The sensor yoke 30 and the resin 31 are fixed to the second shaft 12 via a fixing member 32.

  For example, as shown in FIGS. 3 and 4, the sensor yoke 30 includes a first sensor yoke portion 30 a on the radially inner side and a second sensor yoke portion 30 b on the radially outer side. Both the first sensor yoke portion 30a and the second sensor yoke portion 30b are constituted by a plurality of claw poles 50 and 51 that are annularly arranged in the circumferential direction. The claw poles 50 of the first sensor yoke portion 30a and the claw poles 51 of the second sensor yoke portion 30b are alternately arranged on substantially the same circumference in the circumferential direction. The claw pole 50 is disposed slightly inside the claw pole 51.

  The claw pole 50 of the first sensor yoke portion 30a has, for example, a substantially trapezoidal flat plate-like main body portion 50a and an extending portion 50b extending in a circular arc shape in the circumferential direction from the main body portion 50a as shown in FIG. ing. The main body 50a is arranged such that one narrow end is radially inward and the other wide end is radially outward. The extending portion 50b extends from the radially inner end of the main body 50a to the inside of the radially inner end of the adjacent claw poles 51. The extending portions 50b extend, for example, to the vicinity of the center inside the radially inner end of the adjacent claw poles 51, and the extending portions 50b of the adjacent claw poles 50 are near the center inside the claw pole 51 between them. Are close by. In addition, an R process 50c is applied to an inner angle formed at a connection portion between the main body portion 50a and the extending portion 50b. Thereby, it can prevent that magnetic flux concentrates on the connection part of the main-body part 50a and the extending | stretching part 50b, and it becomes magnetic saturation.

  Similar to the claw pole 50, the claw pole 51 of the second sensor yoke portion 30b has a substantially trapezoidal main body portion 51a and an extending portion 51b extending in an arc shape in the circumferential direction from the main body portion 51a. . The main body 51a is arranged so that one end with a narrow width is on the inside in the radial direction and the other end with a wide width is on the outside in the radial direction. The extending portion 51b extends from the radially outer end of the main body 51a to the outside of the radially outer end of the adjacent claw poles 50. The extending portions 51b extend, for example, to the vicinity of the center of the outer end portions of the adjacent claw poles 50, and the extending portions 51b of the adjacent claw poles 51 are close to each other near the outer center of the claw pole 50 therebetween. Yes. In addition, an R process 51c is applied to an inner angle formed at a connection portion between the main body 51a and the extending portion 51b. Thereby, it can prevent that magnetic flux concentrates on the connection part of the main-body part 51a and the extending | stretching part 51b, and it becomes magnetic saturation.

  For example, eight claw poles 50 and 51 claw poles 51 are arranged, and the total is the same as the number of poles of the permanent magnet 20.

  The positional relationship between the sensor yoke 30 and the permanent magnet 20 when viewed from the axial direction is as shown in FIGS. 5 and 6, for example. That is, the outer end 50 d of the claw pole 50 and the inner end 51 d of the claw pole 51 shown in FIG. 6 are slightly inside the position of the radial end of the permanent magnet 20. By doing so, leakage of magnetic flux from the gap between the claw poles 50 and 51 can be reduced, and the magnetic flux detection range by the torque detector 1 can be increased. As a result, the linearity of the rotation angle and the magnetic flux density in the torque detector 1 can be improved.

  As shown in FIGS. 1 and 2, magnetic collecting yokes 60 for guiding magnetic flux from the sensor yoke 30 are arranged on the inner side and the outer side in the radial direction of the sensor yoke 30. As shown in FIGS. 2 and 3, the magnetism collecting yoke 60 includes a cylindrical first magnetism collecting yoke portion 60 a located inside the sensor yoke 30 and a cylindrical second magnet located outside the sensor yoke 30. It has a magnetism collecting yoke part 60b. The first magnetism collecting yoke part 60 a and the second magnetism collecting yoke part 60 b are arranged concentrically with the sensor yoke 30. The first magnetic flux collecting yoke portion 60a faces the inner peripheral surface of the first sensor yoke portion 30a, that is, the inner peripheral surface of the claw pole 50, and the second magnetic flux collecting yoke portion 60b is the second sensor yoke portion. It faces the outer peripheral surface of 30b, that is, the outer peripheral surface of the claw pole 51. In the present embodiment, since the extending portions 50b and 51b are formed on the inner peripheral surface of the claw pole 50 and the outer peripheral surface of the claw pole 51, respectively, the first magnetism collecting yoke portion 60a and the first sensor yoke portion. The area facing 30a and the area facing the second magnetism collecting yoke portion 60b and the second sensor yoke portion 30b are larger than those where the extending portions 50b and 51b are not formed. As shown in FIG. 1, the magnetism collecting yoke 60 is molded with a resin 61 as a molding material, and is attached to a stationary member (not shown) via the resin 61 as a molding material.

  As described above, the sensor yoke 30 is radially opposed to the magnet collecting yoke 60 and is opposed to the permanent magnet 20 in the axial direction. The sensor yoke 30 and the magnet collecting yoke 60 are molded as shown in FIG. 1, but the opposing surfaces of the sensor yoke 30 and the magnet collecting yoke 60 and the opposing surfaces of the sensor yoke 30 and the permanent magnet 20 are They are exposed to each other.

  The magnetic flux collecting yoke 60 is formed with a magnetic flux concentrating portion 70 for collecting the magnetic flux of the magnetic flux collecting yoke 60 as shown in FIGS. The magnetic flux concentrating portion 70 includes a magnetic flux concentrating portion constituting portion 70a extending in a radial direction from the upper end portion of the first magnetic collecting yoke portion 60a to the outside of the second magnetic collecting yoke portion 60b, and the second magnetic collecting yoke portion 60b. It has a magnetic flux concentrating portion constituting portion 70b extending from the upper end portion to the outside in the radial direction. The magnetic flux concentrating portion constituting portions 70a and 70b are arranged to face each other on the same diameter, and a gap is formed between the magnetic flux concentrating portion constituting portions 70a and 70b. A magnetic flux detector 80 that detects the magnetic flux of the magnetic flux concentrating portion 70 is disposed in the gap.

  As the magnetic flux detector 80, one that can detect the strength of magnetic flux, such as a Hall element, an MR element, or an MI element, is used. In particular, when a Hall IC incorporating a circuit for correcting an output signal is used as the Hall element, thermal demagnetization, offset, gain correction, etc. of the magnet can be performed. In the case of this embodiment, two magnetic flux detectors 80 are used. By using two magnetic flux detectors 80, the sensitivity can be doubled by taking the difference in output, and the zero point drift can be canceled. Further, by using two magnetic flux detectors 80, the sensor signal can be duplicated, and the reliability of magnetic flux detection can be improved.

  Note that three or more magnetic flux detectors 80 may be used. In this case, even if one magnetic flux detector 80 fails, the remaining two or more normal magnetic flux detectors 80 are reliable. High data can be obtained.

  Next, the operation of the torque detector 1 will be described. A schematic diagram of a magnetic circuit in the torque detector 1 is shown in FIG.

  In the torque detector 1, as shown in FIG. 7A, when the relative angle between the sensor yoke 30 and the permanent magnet 20 is "0", the first sensor yoke portion 30a and the second sensor yoke The first and second sensor yoke portions 30a and 30b are connected to the first and second shafts 11 and 12 so that the center line of the portion 30b coincides with the boundary between the north and south poles of the permanent magnet 20 in the axial direction. Fixed. Therefore, when the relative angle between the sensor yoke 30 and the permanent magnet 20 is “0”, the area of the portion of the first and second sensor yoke portions 30a and 30b facing the N pole of the permanent magnet 20 The areas of the first and second sensor yoke portions 30a and 30b facing the south pole of the permanent magnet 20 are the same.

  In this state, the magnetic flux emitted from the N pole of the permanent magnet 20 enters the S pole of the permanent magnet 20 through the first and second sensor yoke portions 30a and 30b. That is, when the relative angle between the sensor yoke 30 and the permanent magnet 20 is “0”, the number of magnetic fluxes entering the first and second sensor yoke portions 30a and 30b is the same as the number of outgoing magnetic fluxes. The magnetic flux emitted from the permanent magnet 20 does not pass through the magnetic collecting yoke 60 and the magnetic flux detector 80.

  On the other hand, in the torque detector 1, as shown in FIG. 7 (B), the sensor yoke 30 is relative to the permanent magnet 20 from the state shown in FIG. The first sensor yoke portion 30a is opposed to only the N pole portion or the S pole portion of the permanent magnet 20, and the second sensor yoke portion 30b is rotated to the S pole portion or N of the permanent magnet 20. The relative angle between the sensor yoke 30 and the permanent magnet 20 is maximized when facing only the pole portion.

  In this state, the number of magnetic fluxes entering and exiting the first and second sensor yoke portions 30a and 30b loses balance, and when the sensor yoke 30 rotates to the right relative to the permanent magnet 20, The magnetic flux emitted from the N pole of the magnet 20 is changed from the first sensor yoke portion 30a to the first magnetic flux collecting yoke portion 60a, the magnetic flux concentration portion constituting portion 70a, the magnetic flux detector 80, the magnetic flux concentration portion constituting portion 70b, and the second concentration. The magnet enters the south pole of the permanent magnet 20 via the magnetic yoke portion 60b and the second sensor yoke portion 30b sequentially. When the sensor yoke 30 rotates in the left direction relative to the permanent magnet 20, the magnetic flux emitted from the N pole of the permanent magnet 20 is changed from the second sensor yoke portion 30b to the second magnetic flux collecting yoke portion 60b. The magnetic flux enters the south pole of the permanent magnet 20 via the concentrating portion constituting portion 70b, the magnetic flux detector 80, the magnetic flux concentrating portion constituting portion 70a, the first magnetic flux collecting yoke portion 60a, and the first sensor yoke portion 30a in this order.

  When the sensor yoke 30 rotates to the right relative to the permanent magnet 20 and the relative angle between the sensor yoke 30 and the permanent magnet 20 is between “0” and the maximum angle, The magnetic flux having the number of magnetic fluxes corresponding to the relative angle between the yoke 30 and the permanent magnet 20 is changed from the first sensor yoke portion 30a to the first magnetic flux collecting yoke portion 60a, the magnetic flux concentration portion constituting portion 70a, the magnetic flux detector 80, The magnetic flux concentrating portion constituting portion 70b, the second magnetism collecting yoke portion 60b, and the second sensor yoke portion 30b are sequentially passed into the S pole of the permanent magnet 20. Further, when the sensor yoke 30 rotates leftward relative to the permanent magnet 20 and the relative angle between the sensor yoke 30 and the permanent magnet 20 is between “0” and the maximum angle, the sensor yoke The magnetic flux having the number of magnetic fluxes corresponding to the relative angle between the magnet 30 and the permanent magnet 20 is changed from the second sensor yoke portion 30b to the second magnetic flux collecting yoke portion 60b, the magnetic flux concentration portion constituting portion 70b, the magnetic flux detector 80, the magnetic flux. The magnetic flux enters the south pole of the permanent magnet 20 via the concentrating portion constituting portion 70a, the first magnetic flux collecting yoke portion 60a, and the first sensor yoke portion 30a sequentially.

  In this case, in the torque detector 1, the sensor yoke 30 and the permanent magnet 20 are fixed to the first or second shafts 11 and 12, respectively, and the first shaft 11 and the second shaft 12 are connected to the torsion bar. 10, when a torsional torque is applied between the first shaft 11 and the second shaft 12, the magnitude (torsional torque amount) and direction of the torsional torque are different from those of the sensor yoke 30. It appears as a relative angle (including direction) to the permanent magnet 20. Therefore, the magnitude and direction of the torsion torque acting between the first shaft 11 and the second shaft 12 can be detected based on the magnetic flux density detected by the magnetic flux detector 80 and the direction thereof. it can.

  According to the above embodiment, since the sensor yoke 30 is disposed to face the permanent magnet 20 in the axial direction, even if the facing area of the sensor yoke 30 and the permanent magnet 20 is widened, the permanent magnet 20 and the sensor yoke 30 are not provided. The axial length can be shortened. As a result, the axial dimension of the entire torque detector 1 can be shortened, and the sensor detector 1 can be miniaturized. In addition, since the sensor yoke 30 is configured using the claw poles 50 and 51, it is easy to manufacture, and as a result, the yield at the time of manufacturing is improved and the cost is reduced. Further, since the inner end portion of the claw pole 50 of the first sensor yoke portion 30a and the outer end portion of the claw pole 51 of the second sensor yoke portion 30b extend in the circumferential direction, the sensor yoke 30 is connected to the claw pole. For example, the facing area between the magnetism collecting yoke 60 and the sensor yoke 30 is not greatly reduced. As a result, high permeance between the magnetism collecting yoke 60 and the sensor yoke 30 is ensured, and the torque can be detected with high accuracy.

  Further, the extending portions 50b of the adjacent claw poles 50 of the first sensor yoke portion 30a extend to the vicinity of the center of the radially inner end of the claw pole 51 of the second sensor yoke portion 30b therebetween, and are close to each other. ing. Further, the extending portions 51b of the adjacent claw poles 51 of the second sensor yoke portion 30b extend to the vicinity of the center of the radially outer end portion of the claw pole 50 of the first sensor yoke portion 30a therebetween, and are close to each other. ing. As a result, the facing area between the magnetism collecting yoke 60 and the sensor yoke 30 is further increased, the permeance between the magnetism collecting yoke 60 and the sensor yoke 30 is improved, and the torque detection accuracy can be improved.

  R processing 50c and 51c are given to the inner corners of the connecting portions between the main body portions 50a and 51a of the claw poles 50 and 51 and the extending portions 50b and 51b. As a result, magnetic flux is prevented from gathering at the connecting portion between the main body portions 50a, 51a and the extending portions 50b, 51b, and magnetic saturation is prevented. As a result, the linearity between the rotation angle and the magnetic flux density in the torque detector 1 is improved. Torque detection accuracy can be improved.

  Further, since the magnetism collecting yoke 60 is disposed opposite to the radial side of the sensor yoke 30, the axial dimension of the entire torque detector 1 can be shortened accordingly, and the sensor detector 1 can be downsized. .

  Further, since the magnetism collecting yoke 60 is disposed inside and outside the sensor yoke 30 in the radial direction and is formed in a cylindrical shape having a width in the axial direction, the opposing area of the magnetism collecting yoke 60 and the sensor yoke 30 is Can be secured sufficiently.

  By the way, the first and second sensor yoke portions 30a and 30b according to the present embodiment are constituted by a plurality of claw poles 50 and 51 having substantially the same shape. For example, as shown in FIG. , 51 may be formed in a row so that the upper and lower sides are alternately switched from the flat plate material 90 by punching. By doing so, the material efficiency can be dramatically improved as compared with the case of making a sensor yoke integrated in an annular shape. In particular, when an expensive metal containing a large amount of nickel is used as a material, the effect of low cost is great.

  In the above embodiment, the first magnetism collecting yoke portion 60a and the second magnetism collecting yoke portion 60b of the magnetism collecting yoke 60 are arranged to face each other in the radial direction of the sensor yoke 30, but are arranged to face each other in the axial direction. It may be. An example of such a case will be described with reference to FIG. In addition, in this example, the same code | symbol is attached | subjected about the structure similar to the said embodiment, and the description is abbreviate | omitted.

  The first magnetism collecting yoke portion 60 a and the second magnetism collecting yoke portion 60 b of the magnetism collecting yoke 60 are arranged on the opposite side of the permanent magnet 20 with respect to the sensor yoke 30. That is, the permanent magnet 20, the sensor yoke 30, and the magnetic collecting yoke 60 are arranged in this order along the axial direction. The first magnetism collecting yoke portion 60a is disposed on the inner end portion of the claw pole 50 of the first sensor yoke portion 30a having the extending portion 50b. The second magnetism collecting yoke portion 60b is disposed on the outer end portion of the second sensor yoke portion 30b having the extending portion 51b. For this reason, when viewed from the axial direction, the magnetic flux collecting yoke portions 60a and 60b are overlapped with the extending portions 50b and 51b of the claw poles 50 and 51, respectively.

  Also in this example, since the facing area between the magnetism collecting yoke 60 and the sensor yoke 30 can be sufficiently secured, high permeance between the magnetism collecting yoke 60 and the sensor yoke 30 is ensured, and the torque can be detected with high accuracy.

  In addition, in the above embodiment, although the main-body parts 50a and 51a of the claw poles 50 and 51 were trapezoidal, this invention is not limited to this, and other shapes may be sufficient.

  Further, the number of poles of the permanent magnet 20 and the number of claw poles 50 and 51 described in the above embodiment are not limited to this and can be arbitrarily selected.

  Further, in the above embodiment, the permanent magnet 20 is attached to the first shaft 11 via the back yoke 21 in order to effectively use the magnetic flux. However, the present invention is not limited to this, and the permanent magnet 20 is attached to the first shaft 11. It may be attached directly to the shaft 11.

  By the way, in the torque detector, it is required to reduce the hysteresis. In order to realize this, conventionally, a sensor yoke or the like is expensive, such as a soft magnetic material containing Ni (for example, permalloy), but magnetic. In general, magnetic annealing is performed after plastic working using a material having excellent characteristics. On the other hand, in the torque detector 1 according to the present invention, since the claw poles 50 and 51 constituting the sensor yoke 30 are flat and do not include bending, the magnetic characteristics are not deteriorated even if processed. For this reason, it is not necessary to perform magnetic annealing at least after processing, and the cost can be reduced.

  Further, in the torque detector 1 according to the present embodiment, when the sensor yoke 30 and the magnetism collecting yoke 60 are compared, the sensor yoke 30 is located closer to the permanent magnet 20, so that the sensor yoke than the magnetism collecting yoke 60 is. 30 is exposed to a stronger magnetic field. Therefore, by using a material having a higher saturation magnetic flux density in the sensor yoke 30 than in the magnetism collecting yoke 60 (for example, permalloy C in the magnetism collecting yoke 60 and permalloy B or silicon steel plate in the sensor yoke 30), torque can be applied with higher accuracy. Can be detected. If Permalloy B or a silicon steel plate having a coercive force that is not so small as compared to Permalloy C is used for both the sensor yoke 30 and the magnetism collecting yoke 60, the hysteresis becomes relatively large. By using permalloy C having a high content and using the permalloy B having a low Ni content for the sensor yoke 30 or using a silicon steel plate, the hysteresis does not become so large and can be practically used. Thus, by using Permalloy C for the magnetic flux collecting yoke 60 and using Permalloy B or a silicon steel plate for the sensor yoke 30, it is possible to reduce the overall cost without significantly degrading the performance.

  Next, an example in which the torque detector 1 is mounted on an electric power steering device will be described. FIG. 10 is an explanatory view showing a cross-sectional view of the periphery of the torque detector 1 in the electric power steering apparatus 100.

  For example, a sensor yoke assembly 102 is fixed to the input shaft 101 as the second shaft on the steering wheel side of the electric power steering apparatus 100 by press fitting or the like. Further, a magnet assembly 104 is fixed to the output shaft 103 as the first shaft on the intermission side by press-fitting or the like. A shaft assembly 105 including an input shaft 101 and an output shaft 103 is inserted inside a magnetic flux collecting yoke assembly 107 fixed to the housing 106.

  For example, as shown in FIG. 11, the sensor yoke assembly 102 includes the above-described sensor yoke 30 and a collar 108 (32 in FIG. 1) for press-fitting and fixing to the input shaft 101. These are synthetic resins 109 (in FIG. 1). 31) and is integrally fixed.

  At this time, the entire sensor yoke 30 is not molded, but the facing surfaces of the magnetic flux collecting yoke assembly 107 facing in the radial direction and the magnet assembly 104 facing in the axial direction are exposed.

  As shown in FIG. 12, the magnetic flux collecting yoke assembly 107 is formed by molding the magnetic flux collecting yoke 60 with a synthetic resin 110 (61 in FIG. 1). However, the synthetic resin 110 (61 in FIG. 1) has a hole 111 for inserting the magnetic detection element so that the magnetic detection element of the magnetic flux detector 80 can be inserted between the magnetic flux concentrating portions 70.

  As shown in FIG. 13, the magnet assembly 104 includes the above-described permanent magnet 20 and a magnet housing 112 (corresponding to 21 in FIG. 1) for fixing the permanent magnet 20. The permanent magnet 20 may be a normal sintered magnet, but may be integrally formed with the magnet housing 112 using a bond magnet or a plastic magnet. Further, the magnet housing 112 (corresponding to 21 in FIG. 1) may be made of a magnetic material to be used as a magnet back yoke.

  Thus, by applying the above-described torque detector 1 to the electric power steering apparatus 100, the electric power steering apparatus 100 can be reduced in size. That is, advantages such as a sufficient amount of EA stroke for absorbing shock at the time of collision can be obtained, and the performance of EPS can be improved.

  The preferred embodiments of the present invention have been described above with reference to the accompanying drawings, but the present invention is not limited to such examples. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the ideas described in the claims, and these are naturally within the technical scope of the present invention. It is understood that it belongs.

It is a longitudinal section showing an outline of composition of a torque detector concerning this embodiment typically. It is a perspective view of the principal part of a torque detector. It is a disassembled perspective view of a torque detector. It is a top view of a sensor yoke. It is explanatory drawing which shows the positional relationship of a sensor yoke and a permanent magnet. It is the elements on larger scale of FIG. It is the schematic of a magnetic circuit for demonstrating operation | movement of a torque detector. It is explanatory drawing which shows the manufacturing method of the claw pole of a torque detector. It is a perspective view of the principal part of a torque detector when a magnetism collecting yoke is arranged opposite to the axial direction of a sensor yoke. It is sectional drawing which shows the torque detector periphery in an electric power steering device. It is a perspective view of a sensor yoke assembly. It is a perspective view of a magnetism collection yoke assembly. It is a perspective view of a magnet assembly.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Torque detector 10 Torsion bar 11 1st axis | shaft 12 2nd axis | shaft 20 Permanent magnet 30 Sensor yoke 30a 1st sensor yoke part 30b 2nd sensor yoke part 50, 51 Claw pole 60 Magnetic collecting yoke 80 Magnetic flux detector

Claims (8)

A first shaft and a second shaft connected coaxially via a connecting shaft;
An annular permanent magnet fixed to one end of the first shaft or the connecting shaft and magnetized in multiple poles along the circumferential direction;
A sensor yoke fixed to the other end of the second shaft or the connecting shaft and forming a magnetic circuit with the permanent magnet;
A magnetism collecting yoke disposed opposite to the sensor yoke, for inducing a magnetic flux from the sensor yoke, and forming the magnetic circuit together with the permanent magnet and the sensor yoke;
A magnetic flux detector for detecting the magnetic flux induced by the magnetic flux collecting yoke,
A torque detector for detecting a torque applied to any one of the first axis and the second axis based on an output of the magnetic flux detector;
The sensor yoke is disposed opposite to the axial direction of the permanent magnet,
The sensor yoke has a first sensor yoke portion on the radially inner side and a second sensor yoke portion on the radially outer side having a plurality of claw poles arranged annularly in the circumferential direction,
The claw poles of the first sensor yoke part and the claw poles of the second sensor yoke part are alternately arranged on the same circumference or substantially the same circumference,
The radially inner end portion of the claw pole of the first sensor yoke portion is extended in the circumferential direction to the inner periphery of the radially inner end portion of the claw pole of the adjacent second sensor yoke portion,
The claw pole radially outer end of the second sensor yoke portion extends in the circumferential direction to the outer periphery of the claw pole radially outer end of the adjacent first sensor yoke portion. , Torque detector. The extension portions of the adjacent claw poles of the first sensor yoke portion extend to the vicinity of the center of the radially inner end portion of the claw pole of the second sensor yoke portion therebetween, and are close to each other.
The extending portions of the adjacent claw poles of the second sensor yoke portion extend to the vicinity of the center of the radially outer end of the claw pole of the first sensor yoke portion therebetween, and are close to each other. The torque detector according to claim 1. The claw pole has a rectangular and flat body part, and an extending part extending in the circumferential direction from a radial end of the body part,
The torque detector according to claim 1 or 2, wherein an R angle is applied to an inner angle of a connection portion between the main body portion and the extending portion.   The torque detector according to any one of claims 1 to 3, wherein the magnetism collecting yoke is disposed opposite to the axial side of the sensor yoke.   The torque detector according to any one of claims 1 to 3, wherein the magnetism collecting yoke is disposed opposite to a radial side of the sensor yoke.   6. The torque detector according to claim 5, wherein the magnetism collecting yoke is disposed inside and outside in a radial direction of the sensor yoke, and each is formed in a cylindrical shape having a width in the axial direction. . In the electric power steering device that generates auxiliary steering torque from the electric motor in response to the steering torque applied to the steering wheel, decelerates by the reducer, and transmits it to the output shaft of the steering mechanism.
An electric power steering apparatus comprising the torque detector according to claim 1. A method of manufacturing a claw pole included in the torque detector according to claim 1,
A method of manufacturing a claw pole, wherein a plurality of claw poles are formed in a row so that the top and bottom are alternately switched by punching.

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