JP5397672B2 - Electric power steering device - Google Patents

Description

  The present invention relates to an electric power steering apparatus.

As a vehicle steering device provided in a vehicle such as an automobile, an electric power steering device that assists steering by an electric motor is known. Some electric power steering apparatuses include a transmission ratio variable mechanism that can change the ratio (transmission ratio) of the output rotation angle to the input rotation angle (see, for example, Patent Document 1). In the electric power steering apparatus according to Patent Document 1, the transmission ratio variable mechanism is arranged coaxially with the steering shaft.
JP 2006-82718 A

Since the vehicle steering device is disposed in a limited space of the vehicle, it is desired to reduce the size thereof. In particular, an electric power steering apparatus including a variable transmission ratio mechanism tends to have a long axial length (a length along the axial direction of the steering shaft), and therefore it is desired to reduce the axial length.
The present invention has been made based on such a background, and an object thereof is to provide an electric power steering apparatus capable of reducing the axial length.

In order to achieve the above object, the present invention is based on the first and second shafts (12, 13) connected coaxially and relatively rotatably, and based on the relative rotation amounts of the first and second shafts. A torque sensor (44) for detecting the magnitude of torque input to one shaft, a steering assist motor (25), a first gear (27) driven by the motor , and a first An annular second gear (28) engaged with the outer gear of the second shaft and connected to the outer periphery of the second shaft so as to be able to rotate together, and a transmission device (26) for transmitting the power of the motor to the second shaft; , Housings (52, 53) for accommodating the second gear, and bearings (82) held by the housing and rotatably supporting the second gear, the second gear being annular Main body (73) and a cylindrical projection projecting laterally from the side surface of the main body 71), and the torque sensor includes an inwardly arranged portion (94) disposed inwardly in the radial direction (R) of the cylindrical protrusion, and the inwardly disposed portion is arranged in the radial direction of the bearing. The inner ring (83) of the bearing is connected to the outer diameter part (71a) of the cylindrical protrusion so as to be able to rotate along with the inner ring (83). An electric power steering device (1) connected to an inner diameter portion (71b) of a cylindrical projection so as to be able to rotate together (Claim 1).

According to the present invention, a part of the torque sensor (inwardly disposed portion) is disposed radially inward of the second gear, so that the axial length of the electric power steering device (the first and second shafts) (Length along the axial direction) can be shortened.
In addition, since a part of the inwardly arranged portion is disposed radially inward of the bearing, the shaft length of the electric power steering device can be further shortened.

Furthermore, by connecting the inner arrangement portion to the inner diameter portion of the cylindrical protrusion so as to be able to rotate together, a part of the torque sensor (inner arrangement portion) can be arranged radially inward of the second gear. . Further, by connecting the inner ring of the bearing to the outer diameter portion of the cylindrical protrusion so as to be able to rotate together, a part of the inner arrangement portion can be arranged radially inward of the bearing. Thereby, the axial length of the electric power steering apparatus can be reliably shortened.

Further, the second shaft and the second gear may be interconnected rotatably together by spline fitting (claim 2). In this case, it is possible to reliably connect the second shaft and the second gear so as to be able to rotate together with a short fitting length. Therefore, the fitting length of the second shaft and the second gear can be shortened, and the shaft length of the electric power steering apparatus can be shortened.
In the above description, the alphanumeric characters in parentheses represent reference numerals of corresponding components in the embodiments described later, but the scope of the claims is not limited by these reference numerals.

Preferred embodiments of the present invention will be described with reference to the accompanying drawings.
FIG. 1 is a schematic diagram showing a schematic configuration of an electric power steering apparatus 1 according to an embodiment of the present invention.
Referring to FIG. 1, an electric power steering apparatus 1 applies a steering torque applied to a steering member 2 such as a steering wheel to each of left and right steered wheels 4L and 4R via a steering shaft 3 as a steering shaft. And has a VGR (Variable Gear Ratio) function capable of changing the transmission ratio θ2 / θ1 as the ratio of the steered wheel turning angle θ2 to the steering angle θ1 of the steering member 2. ing.

  The electric power steering apparatus 1 includes a steering member 2 and a steering shaft 3 connected to the steering member 2. The steering shaft 3 includes first to third shafts 11 to 13 arranged coaxially. The first axis A passing through the central axis of the first to third shafts 11 to 13 is also the rotational axis of the first to third shafts 11 to 13. In this embodiment, the second shaft 12 and the third shaft 13 function as a first axis and a second axis, respectively.

Hereinafter, the axial direction S of the steering shaft 3 is simply referred to as the axial direction S, the radial direction R of the steering shaft 3 is simply referred to as the radial direction R, and the circumferential direction C of the steering shaft 3 is simply referred to as the circumferential direction C.
A steering member 2 is connected to one end of the first shaft 11 so as to be able to rotate together. The other end portion of the first shaft 11 and the one end portion of the second shaft 12 are coupled so as to be differentially rotatable through a transmission ratio variable mechanism 5 as a differential mechanism. The other end of the second shaft 12 and one end of the third shaft 13 are connected via a torsion bar 14 so that they can be elastically rotated relative to each other and can transmit power.

The other end of the third shaft 14 is connected to the steered wheels 4L and 4R via the universal joint 7, the intermediate shaft 8, the universal joint 9, the steering mechanism 10, and the like.
The steered mechanism 10 includes a pinion shaft 15 connected to the universal joint 9, and a rack shaft 16 as a steered shaft that has a rack 16a that meshes with the pinion 15a at the tip of the pinion shaft 15 and extends in the left-right direction of the vehicle. Yes. A knuckle arm 18L is connected to one end of the rack shaft 16 via a tie rod 17L. A knuckle arm 18R is coupled to the other end of the rack shaft 16 via a tie rod 17R.

  With the above configuration, the rotation of the steering member 2 is transmitted to the steering mechanism 10 via the steering shaft 3 and the like. In the turning mechanism 10, the rotation of the pinion 15 a is converted into the axial movement of the rack shaft 16. The axial movement of the rack shaft 16 is transmitted to the corresponding knuckle arms 18L and 18R via the tie rods 17L and 17R, and the knuckle arms 18L and 18R rotate. Thereby, the steered wheels 4L and 4R respectively connected to the knuckle arms 18L and 18R are steered.

  The transmission ratio variable mechanism 5 is for changing the rotational transmission ratio (transmission ratio θ2 / θ1) between the first and second shafts 11 and 12 of the steering shaft 3. The transmission ratio variable mechanism 5 includes an input member 20 provided at the other end of the first shaft 11, an output member 22 provided at one end of the second shaft 12, and the input member 20 and the output member 22. And a bearing ring unit 39 interposed therebetween.

  The input member 20 is connected to the first shaft 11 so as to be coaxial and rotatable, and the output member 22 is connected to the second shaft 12 so as to be coaxial and rotatable. The output member 22 is connected to the steered wheels 4L and 4R via the second shaft 12, the steered mechanism 10, and the like. The first axis A is also the center axis and the rotation axis of the input member 20 and the output member 22.

The bearing ring unit 39 has a second axis B as a central axis inclined with respect to the first axis A, and an inner ring 391 as a first bearing ring and an outer ring as a second bearing ring. 392 and rolling elements 393 such as balls interposed between the inner ring 391 and the outer ring 392.
The inner ring 391 connects the input member 20 and the output member 22 so as to be differentially rotatable, and is engaged with each of the input member 20 and the output member 22 so as to be able to transmit rotation. The inner ring 391 is rotatably supported by the outer ring 392 via the rolling elements 393, so that the inner ring 391 can rotate around the second axis B, and an electric motor as an actuator for driving the outer ring 392 As the transmission ratio variable mechanism motor 23 is driven, it can rotate around the first axis A. The inner ring 391 and the outer ring 392 can perform Coriolis motion (swing motion) around the first axis A.

  The transmission ratio variable mechanism motor 23 constitutes a transmission ratio variable motor, and is arranged coaxially with the first and second shafts 11 and 12 in order to drive the transmission ratio variable mechanism 5. The first axis A is also the central axis of the transmission ratio variable mechanism motor 23. The transmission ratio variable mechanism motor 23 changes the transmission ratio θ2 / θ1 by changing the number of rotations of the outer ring 392 around the first axis A.

The transmission ratio variable mechanism motor 23 is a brushless motor arranged coaxially with the steering shaft 3, and surrounds the cylindrical rotor 231 that holds the raceway ring unit 39, the rotor 231, and is fixed to the housing 24. And a stator 232.
The electric power steering apparatus 1 also includes a steering assist force applying mechanism 19 for applying a steering assist force to the steering shaft 3. The steering assist force applying mechanism 19 includes the second shaft 12 as an input shaft continuous with the output member 22 of the transmission ratio variable mechanism 5, the third shaft 13 as an output shaft continuous with the steering mechanism 10, A torque sensor 44 for detecting the torque transmitted to the second shaft 12, a steering assist motor 25, and a speed reduction mechanism 26 interposed between the motor 25 and the third shaft 13.

The motor 25 is an electric motor such as a brushless motor. The output of the motor 25 is transmitted to the third shaft 13 via the speed reduction mechanism 26.
The speed reduction mechanism 26 includes, for example, a worm gear mechanism, and a worm shaft 27 as a drive gear connected to the output shaft 25a of the motor 25, and a driven gear that meshes with the worm shaft 27 and is connected to the third shaft 13 so as to be able to rotate together. And a worm wheel 28 as a gear. In this embodiment, the worm shaft 27 and the worm wheel 28 function as a first gear and a second gear, respectively.

The driving of the transmission ratio variable mechanism motor 23 and the motor 25 is controlled by a control unit 29 including a CPU, a RAM, and a ROM, respectively. The control unit 29 is connected to the transmission ratio variable mechanism motor 23 via the drive circuit 40 and is connected to the motor 25 via the drive circuit 41.
The control unit 29 includes a steering angle sensor 42, a motor resolver 43 as a rotation angle detection sensor that detects the rotation angle of the rotor 231 of the transmission ratio variable mechanism motor 23, a torque sensor 44, a turning angle sensor 45, and a vehicle speed sensor 46. And a yaw rate sensor 47 are connected to each other.

A signal about the rotation angle of the first shaft 11 is input from the steering angle sensor 42 to the control unit 29 as a value corresponding to the steering angle θ1 that is the operation amount from the straight traveling position of the steering member 2.
A signal about the rotation angle θr of the rotor 231 of the transmission ratio variable mechanism motor 23 is input from the motor resolver 43 to the control unit 29.
A signal about the torque acting on the second shaft 12 is input from the torque sensor 44 to the control unit 29 as a value corresponding to the steering torque T acting on the steering member 2.

A signal about the rotation angle of the third shaft 13 is input from the turning angle sensor 45 to the control unit 29 as a value corresponding to the turning angle θ2.
A signal regarding the vehicle speed V is input from the vehicle speed sensor 46 to the control unit 29.
A signal regarding the yaw rate γ of the vehicle is input from the yaw rate sensor 47 to the control unit 29.

The control unit 29 controls driving of the transmission ratio variable mechanism motor 23 and the motor 25 based on the signals of the sensors 42 to 47 and the like.
With the above configuration, the torque from the steering member 2 and the torque from the transmission ratio variable mechanism 5 are transmitted to the steering mechanism 10 via the steering assist force applying mechanism 19. Specifically, the steering torque input to the steering member 2 is input to the input member 20 of the transmission ratio variable mechanism 5 via the first shaft 11 and input from the input member 20 to the inner ring 391. In addition to torque from the steering member 2, torque from the transmission ratio variable mechanism motor 5 transmitted to the inner ring 391 via the outer ring 392 and the rolling element 393 is transmitted to the inner ring 391, and these torques are output to the output member 22. Is transmitted to. The torque transmitted to the output member 22 is transmitted to the second shaft 12. The torque transmitted to the second shaft 12 is transmitted to the torsion bar 14 and the third shaft 13, and is combined with the output from the motor 25 to rotate through the universal joint 7, the intermediate shaft 8, and the universal joint 9. It is transmitted to the rudder mechanism 10.

Thus, the power transmission path D which transmits the torque of the steering member 2 to the steering mechanism 10 is configured. The power transmission path D includes the first shaft 11, the input member 20, the inner ring 391, the output member 22, the second shaft 12, the torsion bar 14 and the third shaft 13, the universal joint 7, the intermediate shaft 8, and the universal joint. 9 is a route through 9.
FIG. 2 is a partial cross-sectional view showing a more specific configuration of the main part of FIG.

Referring to FIG. 2, the housing 24 is formed in a cylindrical shape as a whole using, for example, a metal such as an aluminum alloy, and includes first to third housings 51 to 53.
The first housing 51 has a cylindrical shape, and includes a differential mechanism housing that houses the transmission ratio variable mechanism 5 as a differential mechanism, a motor housing that houses the transmission ratio variable mechanism motor 23, and a motor resolver 43. The resolver housing to accommodate is comprised. Although not shown, the first housing 51 includes a bus bar for supplying electric power to the transmission ratio variable mechanism motor 23 and a lock mechanism for locking the rotor 231 of the transmission ratio variable mechanism motor 23. Contained.

  One end of the first housing 51 is covered with an end wall member 54. One end of the first housing 51 and the end wall member 54 are fixed to each other using a fastening member 55 such as a bolt. An annular convex portion 57 at one end of the second housing 52 is fitted to the inner peripheral surface 56 at the other end of the first housing 51. The first and second housings 51 and 52 are fixed to each other using a fastening member 58 such as a bolt.

The second housing 52 has a cylindrical shape and constitutes a sensor housing that houses the torque sensor 44. The inner peripheral surface 60 at one end of the third housing 53 is fitted to the outer peripheral surface 59 at the other end of the second housing 52.
The third housing 53 has a cylindrical shape and constitutes a speed reduction mechanism housing that houses the speed reduction mechanism 26. An end wall portion 61 is provided at the other end of the third housing 53. The end wall portion 61 has an annular shape and covers the other end of the third housing 53.

FIG. 3 is an enlarged view of a part of FIG. 2, and shows the speed reduction mechanism 26, the torque sensor 44, and the vicinity thereof. Hereinafter, the worm wheel 28 as the second gear and the torque sensor 44 will be described in detail with reference to FIG.
The worm wheel 28 includes an annular synthetic resin member 72 having a plurality of teeth 72a formed on the outer periphery, a core metal 73 constituting the main body of the worm wheel 28, and a side surface 73a of the core metal 73 (right side surface in FIG. 3). And a cylindrical tubular protrusion 71 extending laterally from the side. The worm wheel 28 is coaxially connected to the third shaft 13, and the radial direction and the axial direction of the worm wheel 28 coincide with the radial direction R and the axial direction S, respectively. In this embodiment, the cored bar 73 and the cylindrical protrusion 71 are integrally formed of, for example, a single material.

  The synthetic resin member 72 is provided along the outer periphery of the core metal 73 and surrounds the periphery of the core metal 73. At least a part of the core metal 73 is embedded in the synthetic resin member 72 using, for example, insert molding, and the synthetic resin member 72 and the core metal 73 are coupled so as to be able to rotate together. The worm shaft 27 is meshed with the outer periphery of the synthetic resin member 72, and the rotation of the motor 25 (see FIG. 1) is transmitted to the worm wheel 28 via the worm shaft 27. The rotation speed is reduced by transmitting the rotation from the worm shaft 27 to the worm wheel 28. In addition, torque is amplified by transmitting rotation from the worm shaft 27 to the worm wheel 28.

  The core metal 73 is connected to the third shaft 13 so as to be able to rotate together, for example, by spline fitting. That is, on the inner periphery of the core metal 73, a female spline portion 74 and a fitted surface 75 a made of a cylindrical surface disposed adjacent to the female spline portion 74 are provided. The metal core 73 is coupled to the third shaft 13 so as to be able to rotate together with the male spline portion 76 formed on the third shaft 13 being engaged with the female spline portion 74. Further, the end of the third shaft 13 is provided with a fitting surface 75b that is lightly press-fitted into the fitting surface 75a, for example, and the third press-fitting of the fitting surface 75a and the fitting surface 75b causes the third to be inserted. The movement of the worm wheel 28 relative to the shaft 13 in the axial direction S and the radial direction R is restricted. Further, the coaxiality between the third shaft 13 and the worm wheel 28 is secured by light press-fitting of the fitted surface 75a and the fitting surface 75b. That is, if the fitted surface 75a and the fitted surface 75b are not provided, the positioning of the third shaft 13 and the worm wheel 28 is the press-fitting of the female spline portion 74 and the male spline 76, and the third shaft 13 There is a possibility that the coaxiality with the worm wheel 28 cannot be secured. In this case, the third shaft 13 is swung around, and as a result, the rotational torque of the steering column may be poor. Therefore, by ensuring the coaxiality of the third shaft 13 and the worm wheel 28 by light press-fitting of the mating surface 75a and the mating surface 75b, the third shaft 13 can be prevented from swinging, and consequently the rotational torque. Can be prevented.

  The outer diameter of the cylindrical surface formed by the fitting surface 75 b provided at the end of the third shaft 13 is smaller than the diameter of the inscribed circle of the female spline portion 74 of the worm wheel 28. When the worm wheel 28 is attached to the third shaft 13, the fitting surface 75 b of the third shaft 13 is fitted to the fitted surface 75 a of the worm wheel 28 prior to the fitting of the spline portions 74 and 76. Match. Thereby, since the 3rd shaft 13 and the worm wheel 28 are centered, both the spline parts 74 and 76 can be fitted smoothly. That is, the fitting surface 75 b functions as a guide surface that guides the fitting of both the spline portions 74 and 76.

  The cored bar 73 is formed as a thick member having an annular shape. The cylindrical protrusion 71 protrudes laterally from the central portion of the side surface 73 a of the core metal 73. The cylindrical protrusion 71 has a cylindrical shape with a constant outer diameter and inner diameter. The outer diameter portion 71a and the inner diameter portion 71b of the cylindrical protrusion 71 are concentric. The center axis of the inner peripheral surface of the core metal 73 coincides with the center axis of the cylindrical protrusion 71. In addition, an annular step portion 81 that coaxially surrounds the cylindrical protrusion 71 is formed at the central portion of the side surface 73 a of the core metal 73.

  A bearing 82 is coaxially fitted on the cylindrical projection 71. More specifically, the bearing 82 is coaxially fitted on a part of the outer diameter portion 71a of the cylindrical protrusion 71 excluding the tip portion. The worm wheel 28 is rotatably supported by the bearing 82. The bearing 82 is, for example, a radial ball bearing, and includes an inner ring 83 and an outer ring 84, and a plurality of rolling elements 85. The inner ring 83 is, for example, press-fitted into the outer diameter portion 71a of the cylindrical protrusion 71 and is coupled so as to be able to rotate together. One end surface (left end surface in FIG. 3) of the inner ring 83 is engaged with the annular step portion 81, and the inner ring 83 is positioned on one side (left side in FIG. 3) in the axial direction S by the annular step portion 81. Yes. The outer ring 84 is held in a bearing holding hole 86 formed in the second housing 52 and is connected to the second housing 52 so as to be able to rotate together. The worm wheel 28 is held by the second housing 52 via a bearing 82.

On the other hand, the torque sensor 44 includes a multi-pole magnet 87, a pair of magnetic yokes 88 and 89 serving as a soft magnetic body that is arranged in a magnetic field generated by the multi-pole magnet 87, and forms a magnetic circuit, and the magnetic yokes 88 and 89. And a Hall IC 92 as a magnetic sensor for detecting the magnetic flux density induced in these magnetism collecting rings 90 and 91.
The multipolar magnet 87 is a cylindrical permanent magnet, and is magnetized so that the N pole and the S pole are alternately switched a plurality of times at equal intervals in the circumferential direction. The multipolar magnet 87 is coupled to the middle portion of the second shaft 12 so as to be able to rotate together. Therefore, when the second shaft 12 and the third shaft 13 rotate relative to each other, the multipolar magnet 87 and the third shaft 13 rotate relative to each other.

  Each of the magnetic yokes 88 and 89 has an annular shape and surrounds the multipolar magnet 87 with a predetermined gap in the radial direction R. Each of the magnetic yokes 88 and 89 faces the outer peripheral surface of the multipolar magnet 87 with a predetermined gap in the radial direction R. Each of the magnetic yokes 88 and 89 is molded in a common synthetic resin member 93 that is an insulator. A part of each of the magnetic yokes 88 and 89 is exposed from the inner peripheral surface of the synthetic resin member 93.

  The synthetic resin member 93 is formed in a cylindrical shape having a constant inner diameter and outer diameter, and its axial length (length along the axial direction S) is longer than that of the multipolar magnet 87. The position of one end (right end in FIG. 3) of the synthetic resin member 93 in the axial direction S is aligned with the multipolar magnet 87, and the other end protrudes to the worm wheel 28 side from the multipolar magnet 87. The other end of the synthetic resin member 93 reaches the inside of the cylindrical protrusion 71 and is predetermined in the axial direction S at a position close to a part of the side surface 73a of the cored bar 73 positioned inside the cylindrical protrusion 71. Is opposed to a part of the side surface 73a. A part of the synthetic resin member 93 disposed inward in the radial direction R of the cylindrical protrusion 71 is an inwardly disposed portion 94. The inwardly arranged portion 94 is an axially extending portion that extends toward the worm wheel 28 along the axial direction S from a portion where the magnetic yokes 88 and 89 are molded in the synthetic resin member 93. A part 95 of the inner arrangement portion 94 is arranged inward in the radial direction R of the bearing 82.

  In addition, a collar 96 made of a metal (for example, carbon steel such as S45C) having a cylindrical shape is connected to the outer diameter portion of the other end portion of the synthetic resin member 93 so as to be able to rotate together. The collar 96 is, for example, press-fitted into the inner diameter portion 71 b of the cylindrical protrusion 71 and is connected to the inner diameter portion 71 b of the cylindrical protrusion 71 so as to be able to rotate together. The inwardly arranged portion 94 is connected to the inner diameter portion 71 b of the cylindrical protrusion 71 via a collar 96 so as to be able to rotate along with the inner protrusion portion 94. In other words, in this embodiment, the entire outer diameter portion 94 a of the inner arrangement portion 94 is a connection portion that is connected to the inner diameter portion 71 b of the cylindrical protrusion 71 so as to be able to rotate together.

  When the worm wheel 28 rotates about its central axis, the collar 96 and the synthetic resin member 93 rotate about the central axis of the worm wheel 28. Therefore, when the second shaft 12 and the third shaft 13 are rotated relative to each other, the worm wheel 28 and the second shaft 12 are rotated relative to each other, and a pair of magnetic yokes 88 and 89 molded on the synthetic resin member 93, The third shaft 13 rotates relative to the third shaft 13. Therefore, when the second shaft 12 and the third shaft 13 are relatively rotated, the multipolar magnet 87 and the magnetic yokes 88 and 89 are relatively rotated.

  The pair of magnetism collecting rings 90 and 91 are annular members formed using a soft magnetic material, and surround the magnetic yokes 88 and 89, respectively. The pair of magnetism collecting rings 90 and 91 are arranged in the axial direction S at a predetermined interval. The pair of magnetism collecting rings 90 and 91 are magnetically coupled to the magnetic yokes 88 and 89, respectively. The pair of magnetism collecting rings 90 and 91 can collect the magnetic flux from the magnetic yokes 88 and 89, respectively, by induction. The pair of magnetism collecting rings 90 and 91 are molded in a cylindrical synthetic resin member 97 together with the Hall IC 92. The Hall IC 92 is disposed between the pair of magnetism collecting rings 90 and 91, and can detect the magnetic flux density generated between the pair of magnetism collecting rings 90 and 91. The torque input to the second shaft 12 is obtained based on the magnetic flux density detected by the Hall IC 92.

  As described above, in the present embodiment, the inwardly arranged portion 94 that is a part of the torque sensor 44 is disposed inward in the radial direction R of the cylindrical protrusion 71 that is a part of the worm wheel 28 as the second gear. Has been. Therefore, the axial length (length along the axial direction S) of the electric power steering apparatus 1 can be shortened. Further, since a part 95 of the inwardly arranged portion 94 is disposed inward in the radial direction R of the bearing 82, the axial length of the electric power steering apparatus 1 can be further shortened.

  Moreover, in this embodiment, the 3rd shaft 13 and the worm wheel 28 are connected so that accompanying rotation is possible by spline fitting. Therefore, compared with the case where the third shaft 13 and the worm wheel 28 are connected so as to be able to rotate together by press-fitting, for example, both can be reliably connected so as to be able to rotate together. Therefore, compared with the case where the 3rd shaft 13 and the worm wheel 28 are connected by press fitting, both fitting length can be shortened. Thereby, the axial length of the electric power steering apparatus 1 can be shortened.

Although the embodiments of the present invention have been described above, the present invention is not limited to the contents of the above-described embodiments, and various modifications can be made within the scope of the claims. For example, in the above-described embodiment, the case where the entire outer diameter portion 94a of the inner arrangement portion 94 is a connection portion has been described. However, a part of the outer diameter portion 94a may be a connection portion.
In the above-described embodiment, the case where the inner arrangement portion 94 is connected to the inner diameter portion 71 b of the cylindrical protrusion 71 via the collar 96 so as to be able to rotate together is described. The side arrangement portion 94 may be directly coupled to the inner diameter portion 71b of the cylindrical protrusion 71 so as to be able to rotate together.

In the above-described embodiment, the case where the speed reduction mechanism 26 is a worm gear mechanism has been described. However, the speed reduction mechanism 26 is not limited to a worm gear mechanism, but may be a parallel shaft gear mechanism using a spur gear or a helical gear. The gear mechanism may be used.

  In addition, various design changes can be made within the scope of matters described in the claims.

It is a mimetic diagram showing a schematic structure of an electric power steering device concerning one embodiment of the present invention. FIG. 2 is a partial cross-sectional view illustrating a more specific configuration of a main part of FIG. 1. It is the figure which expanded a part of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Electric power steering apparatus, 12 ... 2nd shaft (1st axis), 13 ... 3rd shaft (2nd axis), 25 ... Motor, 26 ... Deceleration Mechanism (transmission device), 27 ... Worm shaft (first gear), 28 ... Worm wheel (second gear), 44 ... Torque sensor, 52 ... Second housing (housing) 53 ... Third housing (housing), 71 ... Cylindrical projection, 71a ... Outer diameter part (outer diameter part of cylindrical projection), 71b ... Inner diameter part (inner diameter of cylindrical projection) Part), 73 ... core metal (main body), 82 ... bearing, 83 ... inner ring, 94 ... inner arrangement part, 94a ... outer diameter part (connection part), 95 ... Part of the inwardly arranged portion (portion arranged inwardly in the radial direction of the bearing), R ... radial direction (radial direction of the second gear, radial direction of the bearing) )

Claims (2)

First and second shafts connected to be coaxially rotatable relative to each other;
A torque sensor for detecting the magnitude of torque input to the first shaft based on the relative rotation amounts of the first and second shafts;
A steering assist motor;
A first gear driven by the motor; and an annular second gear meshed with the first gear and connected to the outer periphery of the second shaft so as to be able to rotate along with the second gear . a transmission device for transmitting to the shaft,
A housing that houses the second gear;
A bearing held by the housing and rotatably supporting the second gear,
The second gear includes an annular main body and a cylindrical protrusion protruding laterally from a side surface of the main body,
The torque sensor includes an inwardly arranged portion disposed radially inward of the cylindrical protrusion, and the inwardly disposed portion includes a portion disposed radially inward of the bearing,
The inner ring of the bearing is connected to the outer diameter portion of the cylindrical protrusion so as to be able to rotate together.
The electric power steering apparatus , wherein the inwardly arranged portion is coupled to an inner diameter portion of the cylindrical protrusion so as to be able to rotate together . 2. The electric power steering apparatus according to claim 1, wherein the second shaft and the second gear are connected so as to be able to rotate together by spline fitting.

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