JP5317027B2 - Torque sensor - Google Patents

Description

  The present invention relates to a torque sensor and a manufacturing method thereof, and relates to, for example, an improvement in a torque sensor used in an electric power steering device of an automobile and the manufacturing method thereof.

As a conventional torque sensor, a torque sensor as disclosed in Patent Document 1 is known. In the torque sensor disclosed in Patent Document 1, magnetic rings having different diameters are formed on the outer periphery of a set of magnetic yoke portions (sensor yokes), and these are integrally molded by resin molding.
JP 2007-292549 A

  However, in such a torque sensor, there is a problem that a set of sensor yokes includes ring shapes having different diameters, resulting in poor material removal during manufacturing. Further, it is necessary to take a material for each of the pair of sensor yokes separately and to align them with each other, which causes a problem in that the manufacturing workability is lowered and alignment errors are caused.

  Accordingly, the present invention has been made in view of the above-described problems of the prior art, and an object thereof is to improve the manufacturing yield of torque sensors.

  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 a magnet fixed to the first shaft or one end of the connecting shaft. The first and second sensor yokes are fixed to the other end of the second shaft or the connecting shaft, and are composed of first and second sensor yoke pieces, respectively, the magnet, and the first and second A torque sensor manufacturing method comprising: first and second magnetic flux collecting yokes that form a magnetic circuit together with the sensor yoke; and a magnetic flux detector that detects magnetic flux induced by the first and second magnetic flux collecting yokes A torque sensor that forms the first and second sensor yokes using a flat sensor yoke forming member in which the first and second sensor yoke pieces are alternately connected by a connecting portion. This manufacturing method is configured.

  According to this configuration, since the first and second sensor yoke pieces can be taken out from the flat plate member at a time, the remaining material is reduced and the manufacturing yield is improved. Further, the material can be taken in a state in which the first and second sensor yoke pieces are alternately arranged, that is, in a state in which they are aligned from the beginning.

  In the above configuration, after the sensor yoke forming member is covered with a non-magnetic material and the adjacent first and second sensor yoke pieces are fixed to each other, the first and second sensor yoke pieces between the first and second sensor yoke pieces are fixed. You may make it remove a connection part.

  According to the above configuration, the first and second sensor yokes can be formed while maintaining the positional relationship between the first sensor yoke piece and the second sensor yoke piece defined at the stage of material removal.

  Further, in the above configuration, the sensor yoke forming member is taken out from the flat plate member in a state where the first and second sensor yoke pieces are alternately connected in a strip shape, and the strip-shaped sensor yoke forming member is further curved in an annular shape. You may do it.

  According to the above configuration, since the belt-shaped sensor yoke forming member is taken out and then curved in an annular shape, the material can be removed in a rectangular shape from the flat plate member, so that the remaining material can be further reduced.

  In the above-described configuration, the first and second sensor yoke pieces of the belt-shaped sensor yoke forming member have a wide width portion in which the width in the longitudinal direction of the sensor yoke forming member is larger and a longer width in the longitudinal direction than the wide portion. The strip-shaped sensor yoke forming member having a narrow narrow portion at the top and bottom in the short direction of the sensor yoke forming member is annularly curved with the narrow portion on the inside and the wide portion on the outside. You may make it do.

  According to the above configuration, since the band-shaped sensor yoke forming member is curved with the narrow portion inside, the adjacent first and second sensor yoke pieces come into contact with each other when the belt-shaped sensor yoke forming member is curved in an annular shape. Can be prevented.

  In the above configuration, after the wide portion of the first sensor yoke piece is bent in one of the axial directions and the wide portion of the second sensor yoke piece is bent in the other of the axial directions, the first, The second sensor yoke pieces may be covered with the nonmagnetic material and fixed.

  With the above configuration, the wide portions of the first and second sensor yoke pieces are surfaces facing the first and second magnet yokes, and the narrow portions of the first and second sensor yoke pieces are opposed to the permanent magnet. A torque sensor can be configured as a surface to be used.

  In the above configuration, the sensor yoke forming member may be taken out from the flat plate member in a state where the first and second sensor yoke pieces are alternately connected in an annular shape.

  According to the above configuration, since the annular sensor yoke forming member is taken out from the beginning, the annular sensor yoke can be formed without bending the sensor yoke forming member.

  Further, in the above configuration, one of the first and second sensor yoke pieces of the annular sensor yoke forming member has a protruding portion protruding radially inward from the other, and the other has a radial direction from the other. The first and second sensor yoke pieces may be covered with the non-magnetic material and fixed after the protruding portions are protruded outward, and the respective protruding portions are bent in the axial direction. .

  According to the above configuration, the inner portion can be used effectively and the remaining material can be reduced even if the material is removed in an annular shape.

  As another aspect of the present invention, a first shaft and a second shaft that are coaxially connected via a connecting shaft, a magnet fixed to one end of the first shaft or the connecting shaft, First and second sensor yokes that are fixed to the other end of the second shaft or the connecting shaft and are respectively composed of first and second sensor yoke pieces, the magnet, and the first and second sensors A torque sensor comprising: first and second magnetic flux collecting yokes that form a magnetic circuit together with the yoke; and a magnetic flux detector that detects magnetic flux induced by the first and second magnetic flux collecting yokes, In the first and second sensor yokes, a plurality of the first and second sensor yoke pieces covered with a non-magnetic material are alternately arranged around the axis, and adjacent to the first sensor yoke pieces. Between the sensor yoke piece of 1 and the second sensor yoke piece, the non-magnetic material The gap portion therefore not covered by is formed may constitute a torque sensor according to claim.

  According to the above configuration, the first and second sensor yokes can be formed using the flat sensor yoke forming member in which the first and second sensor yoke pieces are alternately connected by the connecting portion. it can. As a result, it is possible to configure a torque sensor that does not require alignment between the sensor yokes and has good material handling, that is, suitable for manufacturing.

  In the above configuration, the plurality of first sensor yoke pieces and / or the second sensor yoke pieces may be arranged separately from each other.

  According to the above configuration, since the member for connecting the first sensor yoke pieces and / or the second sensor yoke pieces is not necessary, material collection can be improved.

  According to the present invention, the manufacturing yield of the torque sensor can be improved.

Sectional drawing which shows the structure of the torque sensor which concerns on the 1st Embodiment of this invention. The perspective view which shows the sensor yoke of the torque sensor sensor. The perspective view which shows the manufacturing step of the sensor yoke of the torque sensor sensor. The perspective view which shows the manufacturing step of the sensor yoke of the torque sensor sensor. The perspective view which shows the manufacturing step of the sensor yoke of the torque sensor sensor. The perspective view which shows the manufacturing step of the sensor yoke of the torque sensor sensor. (A), (b) is a perspective view which shows the manufacturing step of the sensor yoke of the torque sensor sensor. The principal part perspective view of the torque sensor which concerns on the 2nd Embodiment of this invention. The perspective view which shows the manufacturing step of the sensor yoke of the torque sensor sensor. The perspective view which shows the manufacturing step of the sensor yoke of the torque sensor sensor. The principal part perspective view of the torque sensor which concerns on the 3rd Embodiment of this invention. The perspective view which shows the manufacturing step of the sensor yoke of the torque sensor sensor. The perspective view which shows the manufacturing step of the sensor yoke of the torque sensor sensor.

Hereinafter, first to third embodiments of the present invention will be described in order based on the drawings. In addition, in each drawing, the same code | symbol is attached | subjected to the component which has the same effect | action.
(First embodiment)
A: Overall Configuration First, the overall configuration of the torque sensor according to the first embodiment will be described with reference to FIGS. 1 and 2. Here, FIG. 1 is a sectional view showing a configuration of the torque sensor according to the first embodiment of the present invention, and FIG. 2 is a perspective view showing a sensor yoke of the torque sensor.

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

  A ring-shaped permanent magnet 13 disposed on the outer side in the radial direction is fixed to the first shaft 11. The permanent magnet 13 is multipolarly magnetized in the circumferential direction. A sensor yoke 14 is fixed to the second shaft 12 while being molded with resin. The permanent magnet 13 and the sensor yoke 14 are face-to-face (axially opposed) on one side in the axial direction.

  The permanent magnet 13 is configured by magnetizing an annular hard magnetic material alternately to the north or south pole at a predetermined angular interval in the circumferential direction. In the case of the present embodiment, the permanent magnet 13 is magnetized to the N pole and the S pole at intervals of 22.5 [°]. Therefore, the permanent magnet 13 has a total of 16 poles. In addition, as a magnet material which comprises the permanent magnet 13, 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. 2, the sensor yoke 14 includes a first sensor yoke 15 composed of a first sensor yoke piece 150 and a second sensor yoke 16 composed of a second sensor yoke piece 160. . The first sensor yoke pieces 150 and the second sensor yoke pieces 160 are alternately arranged in a ring shape. The number of the first sensor yoke pieces 150 and the second sensor yoke pieces 160 is selected to be the same as the half of the number of poles of the permanent magnet 13, and here, eight pieces are arranged.

  The first sensor yoke piece 150 has a narrow portion 150A having a flat surface perpendicular to the axial direction, and a flat surface perpendicular to the radial direction that is bent upward in the axial direction from the radially outer end surface of the narrow portion 150A. And a wide portion 150B. The first sensor yoke pieces 150 are spatially separated from each other.

  The second sensor yoke piece 160 has a narrow portion 160A having a flat surface perpendicular to the axial direction, and a flat surface perpendicular to the radial direction that is bent downward in the axial direction from the radially outer end surface of the narrow portion 160A. And a wide portion 160B. The second sensor yoke pieces 160 are spatially separated from each other.

  The narrow portions 150A and 160A are arranged on substantially the same plane with substantially the same thickness, and the width of the flat surface becomes narrower inward in the radial direction. The wide portions 150B and 160B are arranged with substantially the same thickness opposite to each other in the axial direction, and both have flat surfaces that are wider than the narrowest portions of the narrow portions 150A and 160A. Yes. The manufacturing method of the sensor yoke 14 is a characteristic part of the present invention and will be described in detail later.

  A magnetism collecting yoke 17 is disposed so as to face the sensor yoke 14 in the radial direction. More specifically, the magnetism collecting yoke 17 is composed of a cylindrical first magnetism collecting yoke 17A and a second magnetism collecting yoke 17B, and the inner surface in the radial direction of the first magnetism collecting yoke 17A. The radial inner surface of the second magnetism collecting yoke 17B faces the radial outer surface of the wide portion 150A of the first sensor yoke 15 and the radial direction of the wide portion 160A of the second sensor yoke 16 Facing the outer surface. By arranging the magnetism collecting yoke 17 over the entire circumference of the sensor yoke 14 in this way, it is possible to prevent the occurrence of measurement errors due to the relative angle fluctuation between the sensor yoke 14 and the magnetism collecting yoke 17.

  The magnetic flux collecting yoke 17 is provided with a magnetic flux concentrating portion 18. More specifically, the first magnetic flux concentrating portion 18A is formed radially outward from a part of the first magnetic collecting yoke 17A, and the second magnetic flux collecting portion 18A is opposed to the first magnetic flux concentrating portion 18A via a gap. A second magnetic flux concentrating portion 18B is formed outward from the magnetic yoke 17B in the radial direction. By providing the magnetic flux concentrating portion 18 in the magnetic collecting yoke 17 in this way, the magnetic flux passing through the magnetic collecting yoke 17 can be concentrated on the magnetic flux concentrating portion 18.

  A magnetic flux detector (not shown) is disposed between the first and second magnetic flux concentrating portions 18A and 18B. As the magnetic flux detector, a device capable of detecting a magnetic flux, such as a Hall element, an MR element, or an MI element, is used. In particular, it is preferable to use a Hall IC with a built-in circuit for correcting an output signal because the Hall element can perform thermal demagnetization, offset, gain correction, and the like of the magnet.

  By configuring the torque sensor 1 as described above, when torsional torque acts between the first shaft 11 and the second shaft 12, the magnitude (torsional torque amount) and direction of the torsional torque are permanent magnets. 13 and the sensor yoke 14 as a relative angle (including direction). At this time, based on the number of magnetic fluxes detected by the magnetic flux detector and the direction thereof, the distance between the first shaft 11 and the second shaft 12 is determined. The magnitude and direction of the applied torsional torque can be detected. Such a torque sensor 1 can be suitably used for, for example, an electric power steering device of a vehicle.

B: Manufacturing Method of Sensor Yoke Next, a manufacturing method of the sensor yoke 14 of the torque sensor 1 will be described with reference to FIGS. Here, FIGS. 3 to 7 are diagrams for explaining the manufacturing steps of the sensor yoke 14.

First, as shown in FIG. 3, a strip-shaped sensor yoke forming member 20 is prepared. The sensor yoke forming member 20 is taken out, for example, by punching a processed plate with a press. As the plate to be processed, a flat soft magnetic material member having a constant thickness, for example, a Fe-Ni soft magnetic material such as permalloy is used. Since the soft magnetic material has a small coercive force and a high magnetic permeability, the hysteresis of the sensor yoke 14 can be reduced. Incidentally, Sen Sayoku material, hysteresis characteristics required for the sensor, magnetic flux density, the requirements of cost, for example, an electromagnetic soft iron (pure iron), greater high permeability material coercivity than permalloy such as silicon steel, super It is possible to select a high permeability material having a smaller coercive force than permalloy such as malloy and hard palm.

  In the sensor yoke forming member 20, the first sensor yoke pieces 150 and the second sensor yoke pieces 160 are alternately connected in a band shape at the connecting portions 22 (this connecting direction is referred to as a longitudinal direction and a longitudinal direction in the following description). The direction perpendicular to the direction is the short direction). The first and second sensor yoke pieces 150 and 160 have narrow portions 150A and 160A at one end in the short direction, and wide portions 150B and 160B at the other end in the short direction, respectively. The narrow portions 150A and 160A have a rectangular shape whose width in the longitudinal direction becomes narrower toward the end portion. The wide portions 150B and 160B are rectangular, and the width in the longitudinal direction is wider than the width of the narrowest portion of the narrow portions 150A and 160A. With this configuration, the gap between adjacent narrow portions 150A and 160A is larger than the gap between wide portions 150B and 160B.

  Next, as shown in FIG. 4, the belt-shaped sensor yoke forming member 20 is curved in an annular shape. More specifically, the narrow portions 150A and 160A of the first and second sensor yoke pieces 150 and 160 are curved in an annular shape with the radially wide insides and the wide portions 150B and 160B radially outward. Due to the gap between the adjacent narrow portions 150A and 160A, the adjacent first and second sensor yoke pieces 150 and 160 do not come into contact with each other when bent. Further, the deformation force (stress) acting upon bending is concentrated on the connecting portion 22 and is removed as described later, so that the magnetic properties of the sensor yoke 14 are not deteriorated by the bending.

  Next, as shown in FIG. 5, the wide portions 150B and 160B of the first and second sensor yoke pieces 150 and 160 are bent in the opposite directions in the vertical direction with respect to the narrow portions 150A and 160A, respectively. Thereby, the 1st, 2nd sensor yokes 15 and 16 are connected by the connection part 22, and are shape | molded in the state. The step of bending the strip-shaped sensor yoke forming member 20 shown in FIG. 4 and the step of bending the wide portions 150B and 160B shown in FIG. 5 may be reversed.

  Next, as shown in FIG. 6, the first and second sensor yokes 15 and 16 connected by the connecting portion 22 as described above are covered and fixed with a resin 24. At this time, the connecting portion 22 is exposed without being covered with 24. Thereby, it becomes easy to remove the connecting portion 22 in a later process. At this time, a sleeve or the like for stopping the first and second sensor yokes 15 and 16 on the second shaft may be integrally formed at the same time.

  The connecting portion 22 may be covered with the resin 24. In that case, when removing the connecting portion 22 later, the resin 24 may be drilled together. Further, as a member for fixing the first and second sensor yokes 15 and 16, other than the resin 24, for example, an aluminum die-cast holder may be used as long as it is a non-magnetic material.

  Next, as shown in FIG. 7A, the connecting portion 22 that connects the first and second sensor yokes 15 and 16 is removed. Since the connecting portion 22 is not covered with the resin 24, it can be easily removed. As a result, as shown in FIG. 7B, the sensor yoke 14 covered with the resin 24 has a gap 26 formed between the first sensor yoke piece (not shown) and the second sensor yoke piece (not shown). (Not shown).

  Thus, the sensor yoke 14 is formed. Here, since the sensor yoke 14 is formed by the belt-shaped sensor yoke forming member 20 described above, the positional relationship between the first sensor yoke piece 150 and the second sensor yoke piece 160 defined at the stage of material removal. The first and second sensor yokes 15 and 16 can be formed while maintaining the above. That is, alignment is not necessary. Further, since the belt-shaped sensor yoke forming member 20 is taken out and then curved in an annular shape, the remaining material is reduced, and the manufacturing yield is remarkably improved. In particular, when an Fe—Ni-based soft magnetic material such as permalloy is used as the sensor yoke forming member 20, for example, such a soft magnetic material is generally expensive, so that there is a cost advantage due to the suppression of the remaining. large.

(Second Embodiment)
Next, a torque sensor according to the second embodiment will be described focusing on differences from the first embodiment. The difference from the first embodiment is the shape of the sensor yoke, and due to this, the positional relationship with the magnetic flux collecting yoke and the method of manufacturing the sensor yoke are different. This will be described in detail below with reference to FIGS. Here, FIG. 8 is a perspective view of an essential part of the torque sensor according to the second embodiment of the present invention, and FIGS. 9 and 10 are diagrams showing manufacturing steps of the torque sensor.

  As shown in FIG. 8, the sensor yoke 34 and the permanent magnet 13 according to the second embodiment are face-to-face (axially opposed) on one side in the axial direction. The sensor yoke 34 includes a first sensor yoke 35 composed of a first sensor yoke piece 350 and a second sensor yoke 36 composed of a second sensor yoke piece 360. The first sensor yoke pieces 350 and the second sensor yoke pieces 360 are arranged alternately in a ring shape. The numbers of the first sensor yoke pieces 350 and the second sensor yoke pieces 360 are selected to be the same as the half of the number of poles of the permanent magnet 13, and here, eight are arranged.

  Here, the shapes of the first sensor yoke piece 350 and the second sensor yoke piece 360 are different from those of the first embodiment. Specifically, the first sensor yoke piece 350 has a narrow portion 350A having a flat surface perpendicular to the axial direction, and is bent upward in the axial direction from the radially outer end surface of the narrow portion 350A, and is perpendicular to the radial direction. And a wide portion 350B having a flat surface. The second sensor yoke piece 360 has a wide portion 360A having a flat surface perpendicular to the axial direction, and a narrow portion having a flat surface perpendicular to the radial direction, which is bent axially upward from the radially inner side of the wide portion 360A. 360B.

  Unlike the first embodiment, a magnetism collecting yoke 37 is arranged so as to face the sensor yoke 34 in the axial direction. More specifically, the magnetism collecting yoke 37 is composed of a large-diameter ring-shaped first magnetism collecting yoke 37A and a small-diameter ring-shaped second magnetism collecting yoke 37B. The lower surface in the axial direction of the first magnetic flux collecting yoke 37A faces the tip surface (the surface perpendicular to the axial direction) of the wide portion 350B of the first sensor yoke 35, and the second magnetic flux collecting yoke 37B. The lower surface in the axial direction faces the front end surface (a surface perpendicular to the axial direction) of the narrow portion 360B of the second sensor yoke 36. Other configurations of the torque sensor, that is, the magnetic flux concentrating portion, the magnetic flux detector, and the like are the same as those in the first embodiment, and a description thereof is omitted.

  Next, the manufacturing method of the sensor yoke 34 will be described focusing on the differences from the first embodiment. As shown in FIG. 9, in the second embodiment, the sensor yoke forming member 30 in which the first sensor yoke pieces 350 and the second sensor yoke pieces 360 are connected in an annular manner alternately at the connecting portions 32. Prepare. The sensor yoke forming member 30 is taken out, for example, by punching a flat plate using a Fe—Ni soft magnetic material with a press. The first sensor yoke piece 350 has a narrow portion 350A on the radially inner side and a wide portion 350B (protruding portion) on the radially outer side with the connecting portion 32 as a base point. The second sensor yoke piece 360 has a wide portion 360A and a narrow portion 360B (protruding portion) extending further in the radial direction from the wide portion 360A on the radially inner side with the connecting portion 32 as a base point. The radial length of the wide portion 360A is substantially the same as that of the narrow portion 350A.

  Next, as shown in FIG. 10, the wide portions 350B and the narrow portions 360B of the first and second sensor yoke pieces 350 and 360 are oriented in the same direction perpendicular to the narrow portions 350A and the wide portions 360A. Bend it. Thus, the first and second sensor yokes 35 and 36 are molded in a state where they are connected by the connecting portion 32. Since the first and second sensor yokes 35 and 36 in this state are covered and fixed with a resin except for the connecting portion 32, the connecting portion 32 is removed, which is the same as in the first embodiment. Is omitted.

  In the second embodiment, the first and second sensors are maintained while maintaining the positional relationship between the first sensor yoke piece 350 and the second sensor yoke piece 360 defined in an annular shape at the stage of material removal. The yokes 35 and 36 can be formed. Since the sensor yoke 34 is formed by the sensor yoke forming member 30 that is annular from the beginning, the manufacturing efficiency is further increased as compared with the first embodiment because it is not necessary to bend the sensor yoke 34 annularly. Further, since the sensor yoke forming member 30 has a portion (particularly, the narrow portion 360B) protruding radially inward from the connecting portion 32, the inner portion can be used effectively even if the material is removed in an annular shape. The material is reduced, and the production yield is greatly improved.

  The torque sensor according to the second embodiment has a configuration in which the first sensor yoke pieces 350 and the second sensor yoke pieces 360 are spatially separated from each other. In other words, there is no ring portion that connects the first sensor yoke pieces 350 and the second sensor yoke pieces 360 together. Accordingly, the torque sensor according to the second embodiment can be stripped of material like the first embodiment and then bent into an annular shape.

(Third embodiment)
Next, a torque sensor according to a third embodiment will be described focusing on differences from the first and second embodiments. The difference from the first and second embodiments is the shape of the sensor yoke, and due to this, the positional relationship with the permanent magnet and the magnetic collecting yoke and the manufacturing method of the sensor yoke are different. Hereinafter, a detailed description will be given with reference to FIGS. 11 to 13. Here, FIG. 11 is a perspective view of an essential part of a torque sensor according to a third embodiment of the present invention, and FIGS. 11 and 12 are diagrams showing manufacturing steps of the torque sensor.

  As shown in FIG. 11, the sensor yoke 54 according to the third embodiment includes a first sensor yoke 55 composed of a first sensor yoke piece 550 and a second sensor composed of a second sensor yoke piece 560. The yoke 56 is configured. The first sensor yoke pieces 550 and the second sensor yoke pieces 560 are alternately arranged in a ring shape. The number of the first sensor yoke pieces 550 and the second sensor yoke pieces 560 is selected to be the same as the half of the number of poles of the permanent magnet 13, and here, eight pieces are arranged.

  Here, the shapes of the first sensor yoke piece 550 and the second sensor yoke piece 560 are different from those of the first and second embodiments. Specifically, the first sensor yoke piece 550 forms the outer periphery of the sensor yoke 55 and forms an annular shape as a whole, and an extending portion 550A extending radially inward from the ring constituting portion 550B. It consists of and. The second sensor yoke piece 560 is disposed radially inward of the ring component 550B, has a wide portion 560B having a flat surface perpendicular to the radial direction, and radially inward from one axial end of the wide portion 560B. 560A and a narrow portion 560A. The narrow portion 560A is disposed in substantially the same plane as the first sensor yoke piece 550. In the third embodiment, the first sensor yoke pieces 550 are connected to each other by the ring component 550B, and only the second sensor yoke pieces 560 are spatially separated from each other.

  Unlike the first and second embodiments, the magnetism collecting yoke 57 is composed of a large diameter cylindrical first magnetism collecting yoke 57A and a small diameter cylindrical second magnetism collecting yoke 57B. The lower surface in the axial direction of the first magnetism collecting yoke 57A faces the ring component 550B of the first sensor yoke 55, and the radially inner side surface of the second magnetism collecting yoke 57B is in the second direction. It faces the flat surface of the wide portion 560B of the sensor yoke 56.

  In addition, the sensor yoke 54 and the permanent magnet 13 are opposed to each other in the axial direction on one side (axially opposed), but here, unlike the first and second embodiments, the permanent magnet 13 has the above-described collection. It is arranged radially inside the magnetic yoke 57. Thereby, the axial direction length of a torque sensor can be made small. Note that the other configurations of the torque sensor, that is, the magnetic flux concentrator, the magnetic flux detector, and the like are the same as those in the first embodiment, and the description thereof is omitted.

  Next, a method for manufacturing the sensor yoke 54 will be described focusing on the differences from the first and second embodiments. As shown in FIG. 12, in the third embodiment, the sensor yoke forming member 50 in which the first sensor yoke pieces 550 and the second sensor yoke pieces 560 are connected in an annular manner alternately at the connecting portions 52. Prepare. The sensor yoke forming member 50 is taken out, for example, by punching a flat plate using a Fe—Ni soft magnetic material with a press. The connecting portion 52 is disposed radially inside the ring constituting portion 550B of the first sensor yoke piece, and connects the extending portion 550A of the first sensor yoke piece 550 and the second sensor yoke piece 560. . The second sensor yoke piece 560 has a narrow portion 560A on the radially inner side and a wide portion 560B on the radially outer side with the connecting portion 52 as a base point.

  Next, as shown in FIG. 13, the wide portion 560B of the second sensor yoke piece 560 is bent in a direction perpendicular to the narrow portion 560A. Thus, the first and second sensor yokes 55 and 56 are molded in a state where they are connected by the connecting portion 52. The first and second sensor yokes 55 and 56 in this state are covered and fixed with resin except for the connecting portion 52, and then the connecting portion 52 is removed, as in the first embodiment. Therefore, explanation is omitted.

  In the third embodiment, the first and second sensor yokes 55 are maintained while maintaining the positional relationship between the first sensor yoke piece 550 and the second sensor yoke piece 560 defined in the material removal stage. , 56 can be formed. Since the sensor yoke 54 is formed from the sensor yoke forming member 50 that is annular from the beginning, the manufacturing efficiency is further increased as compared with the first embodiment because it is not necessary to bend the sensor yoke 54 into an annular shape. Further, since the sensor yoke forming member 50 has the extending portion 550A, the narrow portion 560A, and the wide portion 560B on the inner side in the radial direction of the ring constituting portion 550B, the inner portion is effective even if the material is removed in an annular shape. Therefore, the remaining material is reduced and the production yield is remarkably improved.

  Although the embodiment of the present invention has been described above, the present invention is not limited to this embodiment and can be implemented in various modes without departing from the scope of the present invention. For example, in each of the embodiments described above, all the first and second sensor yoke pieces (eight pieces each) are collectively extracted from the plate material, but the present invention is not limited to this. For example, the first and second sensor yoke pieces may be taken out from the plate material by half (four pieces each). The number of pairs of the first and second sensor yoke pieces taken out at one time is different from that of the other steps. The balance can be selected as appropriate.

DESCRIPTION OF SYMBOLS 1 ... Torque sensor, 2 ... Connection axis, 11 ... 1st axis, 12 ... 2nd axis, 13 ... Permanent magnet, 14, 34, 54 ... Sensor yoke, 15, 35, 55 ... ... 1st sensor yoke, 150, 350, 550 ... 1st sensor yoke piece, 16, 36, 56 ... 2nd sensor yoke, 160, 360, 560 ... 2nd sensor yoke piece, 17, 37, 57... Magnetic collecting yoke, 17A, 37A, 37B... First magnetic collecting yoke, 17B, 37B, 57B... Second magnetic collecting yoke, 18. Magnetic flux concentrating part, 18B... Second magnetic flux concentrating part, 20, 30, 50... Sensor yoke forming member, 22, 32, 52.

Claims (1)

A first shaft and a second shaft connected coaxially via a connecting shaft;
A magnet fixed to one end of the first shaft or the connecting shaft;
First and second sensor yokes fixed to the other end of the second shaft or the connecting shaft and configured by first and second sensor yoke pieces, respectively.
First and second magnetic flux collecting yokes forming a magnetic circuit together with the magnet and the first and second sensor yokes;
A magnetic flux detector for detecting a magnetic flux induced by the first and second magnetic flux collecting yokes,
In the first and second sensor yokes, a plurality of the first and second sensor yoke pieces covered with a non-magnetic material are alternately arranged around the axis,
Between the adjacent first sensor yoke piece and the second sensor yoke piece, a gap is formed that is not covered by the nonmagnetic material ,
The torque sensor, wherein the plurality of first sensor yoke pieces and / or the second sensor yoke pieces are arranged spatially separated from each other .

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