JP2010122096A - Torque detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a torque detector capable of improving the accuracy of sensor. <P>SOLUTION: In the torque detector including a connection shaft for connecting a first shaft and a second shaft, a permanent magnet fixed to the first shaft and multi-pole magnetized along the circumferential direction, a plurality of magnetic materials and a plurality auxiliary magnetic materials fixed to the second shaft, arranged in a magnetic field of the permanent magnet, and forming a magnetic circuit of the permanent magnet, and a magnetic flux detector detecting a magnetic flux by the induction of the magnetic materials and the auxiliary magnetic materials, the torque detector includes: a first holder integrally holding the plurality of auxiliary magnetic materials; a second holder integrally holding the first holder and a bearing of the second shaft while being arranged side-by-side in the axial direction of the second shaft; and a fixing cover covering the first holder and fixing the first holder to the second holder. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a torque detector, which is suitable for application to, for example, an electric power steering system (EPS).

  2. Description of the Related Art Conventionally, various configurations of torque detectors (torque sensors) for electric power steering devices mounted on automobiles and the like have been proposed.

As one of such torque detectors, a pair of sensor yokes (a multipole yoke and a magnetic yoke) are opposed to the outer peripheral surface of an annular permanent magnet magnetized in the circumferential direction through a gap. And a pair of magnetic flux collecting yokes (magnetic flux collecting rings) so as to face the sensor yokes with a gap between them, and based on the amount of magnetic flux detected by the magnetic flux sensor disposed between the magnetic flux collecting rings. Thus, a torque detector that detects torque generated on the permanent magnet side or the sensor member side has been proposed (see Patent Documents 1 to 4).
Japanese Patent Laid-Open No. 2005-300026 JP 2003-329523 A Japanese Patent Laid-Open No. 2005-265587 Japanese Patent No. 3970852

  By the way, in the above-mentioned Patent Document 1, as a method for fixing the member for fixing the magnetic flux collecting yoke to the gear box, there is a method for inserting the magnetic flux collecting yoke mold body from a direction perpendicular to the shaft axis and fixing with a screw in the same direction. It is disclosed. However, according to the method of fixing on the side as described above, an error occurs in the direction in which the concentricity with the sensor yoke is deviated from the magnetism collecting yoke mold body due to the influence of the assembly error or the expansion due to the temperature change. It is necessary to set an air gap with the yoke. However, when the air gap between the sensor yoke and the magnetism collecting yoke is increased, the amount of leakage magnetic flux is increased, resulting in a problem that the sensor accuracy is lowered.

  The present invention has been made in consideration of the above points, and intends to propose a torque detector capable of improving the sensor accuracy.

  In order to solve such a problem, in the present invention, a connecting shaft that connects the first shaft body and the second shaft body, and the first shaft body are fixed to the first shaft body, and are multipolarly magnetized along the circumferential direction. A permanent magnet, a plurality of magnetic bodies and a plurality of auxiliary magnetic bodies which are fixed to the second shaft body and are arranged in the magnetic field of the permanent magnet, and form a magnetic circuit of the permanent magnet; the magnetic body and the A torque detector having a magnetic flux detector for detecting a magnetic flux induced by the auxiliary magnetic body, the first holder holding the plurality of auxiliary magnetic bodies together, the first holder, and the second holder A second holder for integrally holding a bearing of the shaft body in a state of being aligned in the axial direction of the second shaft body; and the first holder is covered with the second holder. And a fixing cover for fixing.

  As a result, this torque detector can tolerate the effects of axial assembly errors and thermal expansion, minimizing the misalignment of the magnetic material and the air gap between the magnetic material and the auxiliary magnetic material. Can do.

  According to the present invention, a torque detector that can improve sensor accuracy can be realized.

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

(1) Configuration of Electric Power Steering Device FIG. 1 shows an electric power steering device according to this embodiment. As shown in FIG. 1, the electric power steering apparatus according to the present embodiment detects a steering torque generated in the steering shaft 2 in response to the operation of the steering wheel 1 with a torque detector 3, and based on the detection result, The control unit 13 controls the electric motor 12 to generate necessary auxiliary steering torque in the electric motor 12 to assist the steering force of the steering wheel 1.

  A steering shaft 2 connected to the steering wheel 1 includes an input shaft 2A and an output shaft 2B to which a driver's steering force is applied, and a torque detector 3 and a reduction gear are provided between the input shaft 2A and the output shaft 2B. A box 11 is provided. The steering force transmitted to the output shaft 2B of the steering shaft 2 is transmitted to the steering mechanism. Specifically, the steering force is transmitted to the lower shaft 5 through the universal joint 4 and further transmitted to the pinion shaft 7 through the universal joint 6. Further, the steering force transmitted to the pinion shaft 7 is transmitted to the tie rod 9 via the steering gear 8 to steer a steered wheel (not shown). The steering gear 8 is configured as a rack-and-pinion type having a pinion 8A connected to the pinion shaft 7 and a rack 8B meshing with the pinion 8A, and the rotational motion transmitted to the pinion 8A is converted into a linear motion by the rack 8B. Is done.

  An auxiliary steering mechanism 10 that transmits auxiliary steering torque to the output shaft 2B is connected to the output shaft 2B of the steering shaft 2. The auxiliary steering mechanism 10 includes a reduction gear box 11 connected to the output shaft 2B, and an electric motor 12 connected to the reduction gear box 11 and generating auxiliary steering torque. The steering shaft 2, the torque detector 3, and the reduction gear box 11 constitute a column, and the electric motor 12 applies auxiliary steering torque to the output shaft 2B of the column. That is, the electric power steering apparatus in this embodiment is a column assist type.

  The torque detector 3 detects the steering force transmitted to the input shaft 2A via the steering wheel 1 as a steering torque. Details of the torque detector 3 will be described later. The control unit 13 that controls the driving of the electric motor 12 is supplied with electric power from the battery 15 with the ignition switch 14 turned on. The control unit 13 calculates an assist steering command value of the assist command based on the steering torque T detected by the torque detector 3 and the traveling speed V detected by the vehicle speed sensor 16, and the calculated assist steering command value is calculated. Based on this, the supply current value to the electric motor 12 is controlled.

(2) Configuration of Torque Detector According to this Embodiment Next, the configuration of the torque detector 3 mounted on the electric power steering apparatus will be described with reference to FIGS.

  As shown in FIG. 2, the torque detector 3 forms a magnetic circuit with a torsion bar 2C that connects the input shaft 2A and the output shaft 2B, and a permanent magnet assembly 31 that includes a permanent magnet 31A (see FIG. 4). The sensor yoke assembly 32 and the magnetic flux collecting yoke assembly 33, and the detector assembly 34 for detecting the magnetic flux amount of the magnetic flux from the permanent magnet assembly 31 induced by the sensor yoke assembly 32 and the magnetic flux collecting yoke assembly 33 are configured. .

  The torsion bar 2C is a connecting shaft that connects one axial end of the input shaft 2A and one axial end of the output shaft 2B. As shown in FIGS. 2 and 3, the input shaft 2A is covered with a hollow shaft 2D. The gear cover 2E connected to the hollow shaft 2D is attached to the reduction gear box 11, so that the structure (the reduction gear and the torque detector 3) in the reduction gear box 11 is protected. The output shaft 2B is rotatably supported in the reduction gear box 11 by a bearing 30. A steered wheel (not shown) is connected to the other axial end of the output shaft 2B via a universal joint 4 (FIG. 1). It is attached.

  As shown in FIGS. 3 and 4A, the permanent magnet assembly 31 includes a permanent magnet 31A formed as a flat annular body surrounding the output shaft 2C, and a metal back yoke that houses the permanent magnet 31A. 31B. The permanent magnet 31A is configured by alternately magnetizing different magnetic poles (N pole and S pole) in the circumferential direction, and is fixed to the back yoke 31B by bonding.

  The back yoke 31B has an inner peripheral side wall surface 31C as shown in FIG. 4B, and as shown in FIG. 3, the back yoke 31B is press-fitted and fixed to the output shaft 2B so that the inner peripheral side wall surface 31C contacts. ing. It is preferable to employ a ferromagnetic material as the material of the back yoke 31B because the magnetic force of the permanent magnet 31A can be used efficiently.

  In addition, as a magnet material which comprises 31 A of permanent magnets, a ferrite magnet, rare earth magnets (Nd-Fe-B system magnet, Sm-Co system magnet, etc.), a metal magnet, a sintered magnet, etc. are employable. Moreover, you may employ | adopt as a permanent magnet the bond magnet (rubber magnet or plastic magnet) integrally molded with the back yoke 31B.

  The sensor yoke assembly 32 is an annular magnetic body including the first and second sensor yokes 32A and 32B shown in FIG. 5A. The sensor yoke assembly 32 is disposed in the magnetic field of the permanent magnet 31A and forms a magnetic circuit together with the permanent magnet 31A. Form. As shown in FIG. 5 (A), the first sensor yoke 32A includes a plurality of flat plate-like claw portions 32AA and side walls formed by bending the outer periphery of the first sensor yoke 32A perpendicularly to the steering wheel side. Part 32AB. The second sensor yoke 32B includes a plurality of flat plate trapezoidal claw portions 32BA and a side wall portion 32BB formed by bending the outer peripheral portion of the second sensor yoke 32B perpendicularly to the steered wheel side.

  As shown in FIGS. 3, 5B and 7, the first and second sensor yokes 32A and 32B are configured so that the claw portions 32AA and 32BA face each other on one side in the axial direction of the permanent magnet 31A. The molding resin 32C is positioned so that the claw portions 32AA of the first sensor yoke 32A and the claw portions 32AA of the second sensor yoke 32B are alternately positioned in the circumferential direction. 3).

  The side wall portion 32BB of the second sensor yoke 32B is disposed on the radially outer side of the permanent magnet assembly 31. In other words, the permanent magnet assembly 31 is housed in a cylindrical space composed of the side wall portion 32BB and the claw portion 32BA of the second sensor yoke 32B. For this reason, the axial dimension of the structure which consists of the permanent magnet assembly 31 and the sensor yoke assembly 32 can be shortened, and by extension, the axial dimension of the torque detector 3 can be shortened.

  As shown in FIGS. 3, 7, and 8, the magnetic flux collecting yoke assembly 33 is a cylindrical magnetic flux collecting yoke holder that holds the first and second magnetic flux collecting yokes 33BA and 33BB on one surface side of an annular bearing holder 33A. 33C is fixed coaxially, and a fixing cover 33E is fixed to the bearing holder 33A so as to cover the magnetic flux collecting yoke holder 33B via an O-ring 33D.

  In the bearing holder 33A, one end side of the magnetism collecting yoke holder 33C is fitted into the fitting hole 33AX formed in the center portion from the steering wheel side in the axial direction (hereinafter referred to as the upper side in the axial direction), and the bearing 30 (FIG. 3). ) Is fitted from the axial steered wheel side (hereinafter referred to as the axial lower side), and the magnetism collecting yoke holder 33C and the bearing 30 are mounted. As a result, the magnetic flux collecting yoke holder 33B and the bearing 30 can be integrally held in a state of being aligned in the axial direction of the output shaft 2B, and thus the positional relationship between the input shaft 2A and the magnetic flux collecting yoke holder 33C can be accurately maintained. It has been made possible.

  For this reason, a plurality of retaining projections 33AY are provided on the inner peripheral surface of the fitting hole 33AX of the bearing holder 33A at a predetermined interval on the same plane, and the magnetism collecting yoke holder 33C is used as a bearing by the retaining projections 33AY. The holder 33A can be prevented from falling off from the fitting hole 33AX in the axial direction.

  The first and second magnetism collecting yokes 33BA and 33BB are annular auxiliary magnetic bodies provided in correspondence with the first and second sensor yokes 32A and 32B, respectively, and correspond to each other as shown in FIG. The first and second sensor yokes 32A and 32B are held by the magnetic flux collecting yoke holder 33C so as to face the outer peripheral surfaces of the side wall portions 32AB and 32BB.

  As shown in FIG. 9, the first and second magnetic flux collecting yokes 33BA and 33BB are provided with L-shaped fixing protrusions 33BAX and 33BBX at intervals of 120 degrees in the circumferential direction so as to protrude in the radial direction. The fixing projections 33BAX and 33BBX are used to temporarily fix the first and second magnetism collecting yokes 33BA and 33BB to the magnetism collecting yoke holder 33C as will be described later (the main fixing is the bearing holder 33A or the fixing cover 33E). It is made to be able to.

  The first and second magnetic flux collecting yokes 33BA and 33BB are provided with convex portions 33BAY and 33BBY that protrude outward in the radial direction in a state of being opposed to each other and function as magnetic flux concentrating portions. Since the distance between the convex portions 33BAY and 33BBY in the axial direction is narrower than the distance between the first magnetic flux collecting yoke 33BA and the second magnetic flux collecting yoke 33BB in the axial direction, the magnetic flux generated from the permanent magnet 31A is reduced. It can be collected intensively.

  In the present embodiment, it is assumed that the fixing projections 33BAX, 33BBX and the convex portions 33BAY, 33BBY of the first and second magnetic flux collecting yokes 33BA, 33BB are formed by bending by press molding. For example, each of the fixing protrusions 33BAX and 33BBX is bent after extending in the axial direction by at least the curvature radius (r). When the fixing projections 33BAX, 33BBX are formed by a sintering method, a metal powder injection molding method (MIM: Metal Injection Molding) or the like, the degree of freedom in molding the fixing projections 33BAX, 33BBX is increased. The fixing protrusions 33BAX and 33BBX can be formed directly from the outer peripheral surface of the main body of the first and second magnetic flux collecting yokes 33BA and 33BB.

  As shown in FIGS. 7, 10, and 11, the magnetic flux collecting yoke holder 33 </ b> C is formed in a substantially cylindrical shape using a nonmagnetic material such as a resin material. The magnetic flux collecting yoke holder 33C is provided with notches 33CA for exposing the convex portions 33BAY, 33BBY of the first and second magnetic flux collecting yokes 33BA, 33BB, and on the upper end side and the lower end side of the inner peripheral surface. Groove portions 33CB and 33CC are formed, respectively, whereby the first and second magnetic flux collecting yokes 33BA and 33BB are collected so as to fit into the groove portions 33CB and 33CC from the axially upper side or axially lower side of the magnetic flux collecting yoke holder 33C, respectively. The magnetic yoke holder 33C can be mounted.

  Further, concave portions 33CD are provided on the axially upper and lower axial end surfaces of the magnetic flux collecting yoke holder 33C in correspondence with the fixing protrusions 33BAA and 33BBA of the first or second magnetic flux collecting yokes 33BA and 33BB, respectively. When the first and second magnetic flux collecting yokes 33BA and 33BB are fitted into the corresponding grooves 33CB and 33CC of the magnetic flux collecting yoke holder 33C from the upper side in the axial direction or the lower side in the axial direction, respectively, as shown in FIG. The fixing protrusions 33BAX and 33BBX of the first and second magnetic flux collecting yokes 33BA and 33BB are fitted into the corresponding concave portions 33CD of the magnetic flux collecting yoke holder 33C, respectively.

  As shown in FIG. 10B, a claw portion 33CDX having a predetermined shape is provided at the back of each concave portion 33CD, and the first or second magnetic collecting yokes 33BA, 33BB fitted into the concave portion 33CDX. The locking projections 33BAX and 33BBX are locked by the claw portions 33CDX so as not to come out of the concave portion 33CD, whereby the first and second magnetic flux collecting yokes 33BA and 33BB can be fixed to the magnetic flux collecting yoke holder 33C. It is made like that.

  Further, the magnetism collecting yoke holder 33C is formed with first and second detector engaging portions 33CEA and 33CEB protruding in parallel so as to surround the notch portion 33CA, and these first and second detector engaging portions are formed. The detector assembly 34 can be fixed to the magnetic flux collecting yoke holder 33C by fitting a magnetic flux detector 34A described later between the portions 33CEA and 33CEB. For this reason, the first and second detector engaging portions 33CEA and 33CEB have guide projections 34CEAA serving as guides when the detector assembly 34 is fitted, respectively, on the other second or first detector engaging portion 33CEB. , 33CEA, and the guide projection 34CEAA can guide the detector assembly 34 fitted between the first and second detector engaging portions 33CEA, 33CEB to a predetermined position with high accuracy. Has been made.

  The O-ring 33D is made of, for example, an elastic body such as a rubber material, and is disposed so as to be fitted into a groove 33CF formed on the end face on the steering wheel side in the magnetism collecting yoke holder 33C. The O-ring 33D functions as a seal that closes gaps caused by assembly errors of the magnetic flux collecting yoke holder 33C and thermal expansion.

  As is clear from FIG. 7, the fixing cover 33E has an inverted cup shape with an opening formed in the center of the upper surface, and claw portions 33EA are formed at the lower end portion at intervals of 90 degrees along the circumferential direction. Yes. The fixing cover 33E is fixed to the bearing holder 33A by caulking each claw portion 33EA so as to be fitted into a corresponding engagement hole 33AZ formed in the bearing holder 33A.

  As shown in FIGS. 3, 7, 8, and 11, the detector assembly 34 includes a magnetic flux detector 34A composed of a Hall element, MR element, MI element or the like mounted on one surface thereof, and the magnetic flux detector. A harness 34B electrically connected to 34A and the like are provided. A protrusion 34AC is provided on the other surface side of the detector assembly 34, and the protrusion 34AC is formed on the first and second detector engaging portions 33CEA and 33CEB of the magnetism collecting yoke holder 33C. The detector assembly 34 is pushed into the first and second detector engaging portions 33CEA, 33CEB until the detector assembly 34 is inserted into the retaining portion formed between the guide protrusions 33CEAA, 33CEBA (FIG. 7). It is possible to prevent inadvertent detachment from the first and second detector engaging portions 33CEA and 33CEB.

  Further, the magnetic flux detector 34A is closely fixed (adhered) to the convex portions 33BAY and 33BBY of the first and second magnetic flux collecting yokes 33BA and 33BB of the magnetic flux collecting yoke assembly 33 by an adhesive or the like, and thereby the magnetic flux collecting yoke. The distance between the convex portions 33BAY and 33BBY in the first and second magnetic flux collecting yokes 33BA and 33BB of the assembly 33 can be kept constant.

  The detector assembly 34 is integrally molded with the first and second detector engaging portions 33CEA and 33CEB of the magnetic flux collecting yoke holder 33C including a part of the magnetic flux detector 34A and the harness 34B with a molding resin. The mold body 34C made of this molding resin is provided with a gear box fixing portion 34CX having a groove, and the end of the gear box 11 (FIG. 2) is fitted into the gear box fixing portion 34CX during assembly. Thus, the magnetism collecting yoke holder 33B can be fixed to the gear box 11.

  The magnetic characteristics (output hysteresis) are improved by adopting an alloy containing nickel as the material of the first and second sensor yokes 32A and 32B and the first and second magnetic flux collecting yokes 33BA and 33BB. As a result, it is possible to obtain good performance as the torque detector 3. If hysteresis is not a problem, the first and second sensor yokes 32A, other magnetic metals (for example, a rolled steel plate such as a silicon steel plate or SPCC generally used as a material for a motor or the like) are used. 32B and the first and second magnetic flux collecting yokes 33BA and 33BB can be configured. Further, any one of the first and second sensor yokes 32A and 32B and the first and second magnetic flux collecting yokes 33BA and 33BB may be configured using an alloy containing nickel.

  The magnetic collecting yoke assembly 33 and the detector assembly 34 having the above configuration are coupled in the following procedure. First, the detector assembly 34 is attached to the magnetic flux collecting yoke holder 33C so as to be inserted into the first and second detector engaging portions 33CEA and 33CEB of the magnetic flux collecting yoke holder 33C. After that, the molded body 34C is formed by molding the magnetic flux detector 34A and the like of the detector assembly 34 integrally with the first and second detector engaging portions 33CEA and 33CEB of the magnetic flux collecting yoke holder 33C by molding resin. To do.

  Next, the first and second magnetic flux collecting yokes 33BA and 33BB are attached to the magnetic flux collecting yoke holder 33C. At this time, the convex portions 33BAY and 33BBY of the first and second magnetic flux collecting yokes 33BA and 33BB are firmly fixed to the magnetic flux detector 34A of the detector assembly 34 by an adhesive. Thereafter, the magnetism collecting yoke holder 33C is attached to the bearing holder 33A, and the O-ring 33D is fitted into the groove 33CF on the upper side in the axial direction of the magnetism collecting yoke holder 33C from the upper side in the axial direction of the magnetism collecting yoke holder 33C and fixed.

  Next, the principle of torque detection of the torque detector 3 according to this embodiment will be described with reference to FIG. FIG. 12 shows the positional relationship between the permanent magnet 31 </ b> A constituting the torque detector 3 and the first sensor yoke 32 </ b> A. In FIG. 12, the second sensor yoke 32B and the like are omitted in order to clarify the positional relationship between the claw portion 32AA of the first sensor yoke 32A and the permanent magnet 31A. As described above, the claw portion 32BA of the second sensor yoke 32B is disposed between the claw portions 32AA of the sensor yoke 32A.

  When no torque is input to the torque detector 3, each of the claw portions 32AA of the first sensor yoke 32A is positioned on the boundary between the magnetic poles (N pole and S pole) constituting the permanent magnet 31A. Since the permeance (reciprocal of the magnetic resistance) with respect to the N pole and S pole of the permanent magnet 31A viewed from the claw portion 32AA is equal, the magnetic flux flows as shown in FIG. Specifically, the magnetic flux generated from the N pole of the permanent magnet 31A enters the claw portion 32AA of the first sensor yoke 32A and enters the S pole of the permanent magnet 31A as it is. Therefore, the magnetic flux does not flow through the magnetic flux detector 34A.

  When the driver rotates the steering wheel 1 from this state and torque is applied to the input shaft 2A, the input side of the torsion bar 2C rotates in the same manner as the steering wheel 1 and the torsion bar 2C itself responds to the input torque. Twist occurs. This twist causes relative angular displacement between the input side and the output side of the torsion bar 2C. The relative angular displacement generated between the input side and the output side of the torsion bar 2C appears as a relative angular displacement between the permanent magnet 31A of the torque detector 3 and the first sensor yoke 32A.

  When a relative angular displacement occurs between the permanent magnet 31A and the first sensor yoke 32A, the balance of permeance as shown in FIG. 12 is lost, and a magnetic circuit including the magnetic flux detector 34A (ie, from the N pole of the permanent magnet 31A). The generated magnetic flux flows into the claw portion 32AA of the first sensor yoke 32A, and from the first sensor yoke 32A to the convex portion 33BAY of the first magnetic flux collecting yoke 33BA, the magnetic flux detector 34A, and the second magnetic flux collecting yoke 33BB. Magnetic flux flows through the convex portion 33BBY and the second sensor yoke 32B to the magnetic circuit returning from the claw portion 32BA of the second sensor yoke 32B to the S pole of the permanent magnet 31A. By detecting the magnetic flux generated in the magnetic circuit including the magnetic flux detector 34A by the magnetic flux detector 34A, the relative angular displacement can be measured, and the torque applied to the torsion bar 2C can be detected.

(3) Effects of this Embodiment As described above, in the torque detector 3 according to this embodiment, the fixing cover 33E for fixing the magnetism collecting yoke holder 33C of the magnetism collecting yoke assembly 33 to the bearing holder 33A from the axial direction is provided. By providing the magnetic flux collecting yoke assembly 33, it is possible to allow the effects of assembly and thermal expansion of the magnetic flux collecting yoke holder 33C or the like in the axial direction, and to prevent misalignment with the first and second sensor yokes 32A and 32B. The air gap between the first and second sensor yokes 32A, 32B and the first and second magnetism collecting yokes 33BA, 33BB can be minimized, and the sensor accuracy can be improved.

  In the torque detector 3 according to the present embodiment, the magnetic flux detector 34A is sandwiched between the convex portions 33BAY and 33BBY of the first and second magnetic collecting yokes 33BA and 33BB after the magnetic flux detector 34A is fixed at a predetermined position. Therefore, there is no need to provide a gap during assembly between the convex portions 33BAY and 33BBY of the first and second magnetic flux collecting yokes 33BA and 33BB, and the convex portions of the first and second magnetic flux collecting yokes 33BA and 33BB. The air gap between 33BAY and 33BBY can be minimized. As a result, the magnetic flux collecting yoke assembly 33 and thus the torque detector 3 can be made thin as a whole.

(4) Other Embodiments In the above-described embodiment, the case where the detector assembly 34 is fixed to the magnetic flux collecting yoke holder 33C of the magnetic flux collecting yoke assembly 33 has been described. However, the present invention is not limited to this. Alternatively, the detector assembly 34 may be fixed to the bearing holder 33 </ b> A of the magnetic flux collecting yoke assembly 33 after the magnetic flux collecting yoke assembly 33 is assembled. Further, the magnetic flux detector 34A of the detector assembly 34 and one of the first or second magnetic flux collecting yokes 33BA and 33BB are integrally molded with a molding resin, and the other second or first magnetic flux collector is formed on the molded product. The magnetic flux detector 34A may be sandwiched between the first and second magnetic flux collecting yokes 33BA, 33BB by assembling the magnetic yokes 33BB, 33BA.

  In the above-described embodiment, the case where the fixing cover 33E of the magnetism collecting yoke assembly 33 is fixed to the bearing holder 3A by caulking has been described. However, the present invention is not limited thereto, for example, as shown in FIG. The fixing cover 50 may be fixed to the bearing holder 3 </ b> A with a bolt 51.

  The present invention can be widely applied to torque detectors for various uses in addition to torque detectors used in electric power steering devices.

It is a basic diagram which shows the whole structure of the electric power steering device to which the torque detector by this Embodiment is applied. It is a disassembled perspective view which shows the structure of the torque detector by this Embodiment. It is sectional drawing which shows the structure of the torque detector by this Embodiment. (A) is a perspective view which shows the structure of a permanent magnet assembly, (B) is an exploded perspective view which shows the structure of a permanent magnet assembly. (A) And (B) is a perspective view which shows the structure of the 1st and 2nd sensor yoke. It is a basic diagram with which it uses for description of the positional relationship of the 1st and 2nd sensor yoke and the 1st and 2nd magnetism collection yoke. (A) is an exploded perspective view showing a configuration of the magnetic flux collecting yoke assembly, and (B) is a perspective view showing a configuration of the magnetic flux collecting yoke assembly. It is sectional drawing which shows the structure of a magnetism collection yoke assembly. It is a perspective view which shows the structure of the 1st and 2nd magnetism collection yoke. (A) is a top view showing the configuration of the magnetic flux collecting yoke holder, and (B) is a cross-sectional view showing the configuration of the magnetic flux collecting yoke holder. (A) is a top view showing the configuration of the magnetic flux collecting yoke assembly, and (B) is a cross-sectional view showing the configuration of the magnetic flux collecting yoke assembly. It is a conceptual diagram with which it uses for operation | movement description of the torque detector by this Embodiment. It is a perspective view with which it uses for description of other embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Electric power steering device, 2 ... Steering shaft, 2A ... Input shaft, 2B ... Output shaft, 2C ... Torsion bar, 3 ... Torque detector, 12 ... Electric motor, 31 ... Permanent magnet Assembly, 31A ... Permanent magnet, 31B ... Back yoke, 32 ... Sensor yoke assembly, 32A, 32B ... Sensor yoke, 32AA, 32BA ... Claw part, 32AB, 32BB ... Side wall part, 32C ... Molding resin , 33... Magnetic collecting yoke assembly, 33 A... Bearing holder, 33 AX... Fitting hole, 33 AY... Protrusion for retaining, 33 AZ ... Engaging hole, 33 BA, 33 BB ... Magnetic collecting yoke, 33 BAX, 33 BBX ... Protrusion for fixing, 33BAY, 33BBY ... Convex part, 33C ... Magnetic flux collecting yoke holder, 33CB, 33CC ... Groove part, 33CF ... Groove, 33CD ...... Recess, 33CDX, 33EA ... Claw, 33CEA, 33CEB ... Detector engaging part, 34 ... O-ring, 35 ... Fixing cover 34 ... Detector assembly, 34A ... Magnetic flux Detector, 34C: Mold body, 34CX: Gearbox fixing part.

Claims (19)

A connecting shaft that connects the first shaft body and the second shaft body, a permanent magnet fixed to the first shaft body and multipolarly magnetized along a circumferential direction, and the second shaft body A plurality of magnetic bodies and a plurality of auxiliary magnetic bodies that are fixed and arranged in the magnetic field of the permanent magnet and form a magnetic circuit of the permanent magnets, and a magnetic flux that detects a magnetic flux induced by the magnetic bodies and the auxiliary magnetic bodies A torque detector having a detector,
A first holder for integrally holding the plurality of auxiliary magnetic bodies;
A second holder that integrally holds the bearings of the first holder and the second shaft body in a state of being aligned in the axial direction of the second shaft body;
A torque detector, comprising: a fixing cover that covers the first holder and fixes the first holder to the second holder. The torque detector according to claim 1, further comprising an elastic body interposed between the fixing cover and the first holder. The torque detector according to claim 2, wherein a groove for fitting the elastic body is provided on a contact surface of the first holder with the elastic body. The torque detector according to claim 1, wherein the fixing cover is fixed to the second holder. The torque detector according to claim 4, wherein the fixing cover is fixed to the second holder by caulking. The torque detector according to claim 4, wherein the fixing cover is fixed to the second holder with a bolt. The torque detector according to claim 1, wherein the first holder is provided with a groove for fitting the auxiliary magnetic body in the axial direction of the first shaft body. The auxiliary magnetic body is provided with one or more fixing protrusions,
The first holder is provided with one or a plurality of recesses into which the fixing protrusions of the auxiliary magnetic body are fitted when the auxiliary magnetic body is fitted from the axial direction of the first shaft body. The torque detector according to claim 7. The torque detector according to claim 8, wherein the concave portion is provided with a claw portion for fixing the fixing protrusion of the auxiliary magnetic body fitted in the concave portion. The torque detector according to claim 1, wherein the first holder is provided with a concave portion and / or a convex portion for positioning when the first holder is fixed to the second holder. The first holder is held by the second holder so as to be fitted into a fitting hole provided in a central portion of the second holder,
The torque detector according to claim 1, wherein a projection for preventing the first holder from falling off is provided in the fitting hole of the second holder. The torque detector according to claim 1, wherein the auxiliary magnetic body and the magnetic flux detector are closely fixed. The torque detector according to claim 1, further comprising a detector assembly in which the magnetic flux detector and a harness electrically connected to the magnetic flux detector are integrated. The torque detector according to claim 13, wherein the detector assembly is integrally fixed to the first holder. The torque detector according to claim 14, wherein the detector assembly is fixed by being molded integrally with the first holder. The torque detection according to claim 15, wherein the mold body that integrally molds the detector assembly and the first holder is provided with a fitting portion with a box that houses the torque detector. vessel. The torque detector according to claim 14, wherein the first holder is provided with an engagement portion for fixing the detector assembly. The torque detector according to claim 17, wherein a guide for positioning the detector assembly at a predetermined position is provided in the engagement portion. The torque detector according to claim 18, wherein the guide is provided with a retaining portion for preventing the detector assembly from coming off.

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