JP2010052508A - Vehicular steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vehicular steering device capable of transmitting the sufficient torque between a steering shaft and a member to be connected to the steering shaft out of a transmission ratio variable mechanism, preventing any play between the two components, reliably regulating detachment of the two components in the axial direction, and reducing its size. <P>SOLUTION: A transmission ratio variable mechanism 5 includes an input member 20 with a first shaft 11 being fitted thereto, an output member 22 with a second shaft 22 being fitted thereto, and an inner ring 391 for connecting these members 20, 22 in a differentially rotatable manner. The first shaft 11 and the input member 20 are connected to each other by a spline fitting part 138 as a first connection element, and connected by a tight-fitting part 137 as a second connection element. Further, detachment of the input member 20 from the first shaft 11 is prevented by a push nut 121 as a third connection element. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a vehicle steering apparatus.

As a transmission ratio variable mechanism capable of changing a transmission ratio as a ratio of an output rotation angle to an input rotation angle, a mechanism using a rocking gear mechanism is known (for example, see Patent Document 1).
The oscillating gear mechanism includes first and fourth gears facing each other, and an oscillating gear disposed between the first and fourth gears and inclined with respect to the first and fourth gears. The swing gear includes a second gear that meshes with the first gear and a third gear that meshes with the fourth gear. The fourth gear is fitted to the output shaft.
JP 2008-133861 A

  When the oscillating gear mechanism is applied to a vehicle steering apparatus, the output shaft functions as a steering shaft connected to the steering mechanism. The coupling structure between the fourth gear and the output shaft is preferably such that no rattling occurs between them. There is also a demand for shortening the overall length of the vehicle steering system. Further, it is preferable that the fourth gear is reliably restricted from coming off in the axial direction with respect to the output shaft.

  Therefore, the present invention can transmit sufficient torque between the steering shaft and a member connected to the steering shaft of the transmission ratio variable mechanism, and can prevent rattling from occurring between them. It is an object of the present invention to provide a vehicle steering apparatus that can reliably restrict both of them from coming off in the axial direction and can achieve downsizing.

  In order to achieve the above object, the present invention changes the transmission ratio (θ2 / θ1), which is the ratio of the turning angle (θ2) of the steered wheels (4L, 4R) to the steering angle (θ1) of the steering member (2). The transmission ratio variable mechanism (5) is provided. The transmission ratio variable mechanism has a central axis on the first axis (A), one of which constitutes the input shaft (11) and the other one of which is the output shaft (12). A pair of shafts that are configured to rotate together with each of the pair of shafts, one of which forms an input member (20) and the other of which forms an output member (22), A pair of cylindrical members connected to each other so as to be differentially rotatable, and an intermediate member (391) rotatable around a second axis (B) inclined with respect to the first axis, First (138, 158) and second (137, 157) connecting at least one of the shafts and the corresponding cylindrical member And a third connecting element (121, 141), wherein the first connecting element includes a spline fitting portion or a serration fitting portion, and the second connecting element includes a loose fit portion or a tight fit portion, The third coupling element is provided on the vehicle steering apparatus (1), and includes a push nut that is locked to at least one of the pair of shafts and prevents the corresponding cylindrical member from being detached. (Claim 1).

  According to the present invention, by providing a loose fit part or a tight fit part as the second connecting element, it is possible to close a gap between at least one of the pair of shafts and the corresponding cylindrical member, It is possible to prevent rattling between the two. Moreover, the spline fitting part or the serration fitting part is provided as a 1st connection element. Thus, even when a large torque is input between at least one of the pair of shafts and the corresponding cylindrical member, the large torque is transmitted by the first coupling element in cooperation with the second coupling element. And a sufficient torque transmission capacity can be secured. Further, by providing the push nut as the third connecting element, it is possible to prevent the corresponding cylindrical member from being detached from at least one of the pair of shafts. Moreover, since the second connecting element does not need to transmit a large torque, the overall length can be shortened, and the push nut is usually thin. As a result, it is possible to reduce the size and weight of the device and reduce the component cost through shortening the overall length of the device.

Moreover, in this invention, it arrange | positions in order of a 1st connection element, a 2nd connection element, and a 3rd connection element regarding the direction (D1, D2) with which the axis | shaft corresponding to the said corresponding cylindrical member is mounted | worn. (Claim 2).
In this case, the spline fitting portion or the serration fitting portion as the first connecting element is arranged on the upstream side in the direction in which the shaft corresponding to the corresponding cylindrical member is mounted. Thereby, when attaching a corresponding cylindrical member to a corresponding axis | shaft, it can make it easy to visually recognize a spline fitting part or a serration fitting part. Thereby, it is possible to easily perform phase alignment in the circumferential direction of the corresponding cylindrical member and the corresponding shaft.

  In the present invention, at least one of the pair of shafts includes a small diameter portion (131, 151) provided at the shaft end (11b, 12a) and a large diameter portion (132, 152) adjacent to the small diameter portion. And an annular positioning step (124, 144) formed between the large diameter portion and the small diameter portion, the push nut is fitted to the small diameter portion, and the corresponding cylindrical member is A cylindrical portion (202, 222) that is spline-fitted or serrated-fitted to the large-diameter portion, and extends radially inward from the cylindrical portion, and is fitted loosely or tightly to the outer periphery of the small-diameter portion. In some cases, the extending portion includes an annular extending portion (203, 223), and the extending portion is sandwiched between the push nut and the positioning step portion.

In this case, the extending part of the corresponding cylindrical member is sandwiched between the push nut and the positioning step part. Thereby, it can restrict | limit reliably that a corresponding cylindrical member moves to an axial direction with respect to the corresponding axis | shaft.
In the above description, numbers 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 a vehicle steering apparatus 1 including a transmission ratio variable mechanism according to an embodiment of the present invention. Referring to FIG. 1, a vehicle steering apparatus 1 applies a steering torque applied to a steering member 2 such as a steering wheel to 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 vehicle 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 as first to third shafts arranged coaxially with each other. The first axis A as 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.

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.
The steering member 2 is connected to one end 11a of the first shaft 11 so as to be able to rotate together. The other end 11b of the first shaft 11 and the one end 12a of the second shaft 12 are coupled so as to be differentially rotatable via a transmission ratio variable mechanism 5 as a differential mechanism. The other end 12b 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 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. Knuckle arms 18L and 18R are connected to the pair of ends of the rack shaft 16 via tie rods 17L and 17R, respectively.

  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. Accordingly, the corresponding steered wheels 4L and 4R connected to the knuckle arms 18L and 18R are respectively steered.

  The transmission ratio variable mechanism 5 is for changing the rotation transmission ratio (transmission ratio θ2 / θ1) between the first and second shafts 11 and 12 of the steering shaft 3, and is a nutation gear mechanism. . The transmission ratio variable mechanism 5 includes the first and second shafts 11 and 12 as a pair of shafts, the input member 20 provided on the other end 11b of the first shaft 11, and the second shaft 12. The output member 22 provided in the one end 12a and the track ring unit 39 interposed between the input member 20 and the output member 22 are included.

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 first axis A is also the center axis and the rotation axis of the input member 20 and the output member 22.
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 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 constitutes an intermediate member. 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 rotatable about the second axis B by being rotatably supported by the outer ring 392 via the rolling elements 393. Further, the inner ring 391 can rotate around the first axis A as the transmission ratio variable mechanism motor 23, which is an electric motor as an actuator for driving the outer ring 392, is driven. 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 vehicle steering apparatus 1 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 torque transmitted between the second shaft 12 and the third shaft 13, a steering assist motor 25 as a steering assist actuator, the steering assist motor 25, and a third shaft. 13 and a speed reduction mechanism 26 interposed between them.

The steering assist motor 25 is an electric motor such as a brushless motor. The output of the steering assist motor 25 is transmitted to the third shaft 13 via the speed reduction mechanism 26.
The speed reduction mechanism 26 is composed of, for example, a worm gear mechanism, and is connected to a worm shaft 27 as a drive gear connected to the output shaft 25 a of the steering assist motor 25, meshed with the worm shaft 27 and connected to the third shaft 13 so as to be able to rotate together. And a worm wheel 28 as a driven gear.

The transmission ratio variable mechanism 5 and the steering assist force applying mechanism 19 are accommodated in a housing 24. The housing 24 is disposed in a passenger compartment (cabin) of the vehicle. The housing 24 may be disposed so as to surround the intermediate shaft 8 or may be disposed in the engine room of the vehicle.
The driving of the transmission ratio variable mechanism motor 23 and the steering assist 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 steering assist 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 amount of operation from the straight travel position of the steering member 2.

From the motor resolver 43, a signal regarding the rotation angle θr of the rotor 231 of the transmission ratio variable mechanism motor 23 is input.
From the torque sensor 44, a signal regarding the torque acting between the second and third shafts 12 and 13 is input as a value corresponding to the steering torque T acting on the steering member 2.
From the turning angle sensor 45, a signal regarding the rotation angle of the third shaft 13 is input as a value corresponding to the turning angle θ2.

A signal about the vehicle speed V is input from the vehicle speed sensor 46.
A signal regarding the yaw rate γ of the vehicle is input from the yaw rate sensor 47.
The control unit 29 controls the driving of the transmission ratio variable mechanism motor 23 and the steering assist motor 25 based on the signals of the sensors 42 to 47.
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 steering assist motor 25 via the universal joint 7, the intermediate shaft 8, and the universal joint 9. Is transmitted to the steering mechanism 10.

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, constitutes a differential mechanism housing that houses the transmission ratio variable mechanism 5 as a differential mechanism, and cooperates with the second housing 52 to change the transmission ratio. A motor housing that houses the mechanism motor 23 is configured. 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 (not shown) such as a bolt.

The second housing 52 has a cylindrical shape, and constitutes a sensor housing that houses the torque sensor 44, a resolver housing that houses the motor resolver 43, and a part of the motor housing of the transmission ratio variable mechanism motor 23. ing. 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 the vicinity of the opposed ends 11b and 12a of the first shaft 11 and the second shaft 12 of FIG. Referring to FIG. 3, the input member 20, the output member 22, and the bearing ring unit 39 of the transmission ratio variable mechanism 5 each have an annular shape. The input member 20 and the output member 22 constitute a pair of cylindrical members.
The input member 20 is integrally formed as a whole using a single member, and includes an input member main body 201 and an input member cylindrical portion 202 disposed radially inward of the input member main body 201. Yes.

The input member 20 is rotatably supported by an annular convex portion 92 described later of the first housing 51 via the first bearing 31.
The first shaft 11 which is an input shaft as one of a pair of shafts is inserted into the input member cylindrical portion 202, and the input member cylindrical portion 202 and the first shaft 11 can rotate together. It is connected to.

  Specifically, the other end portion 11 b of the first shaft 11 includes a locked portion 122 to which the push nut 121 is locked, a press-fit portion 123 that is press-fitted into the input member tubular portion 202, and a press-fit portion 123. On the other hand, an annular positioning step 124 that is disposed on one side S1 in the axial direction S and extends radially outward with respect to the press-fit portion 123, and is disposed on one S1 side in the axial direction S with respect to the positioning step 124. And a male spline portion 125.

  Further, the inner peripheral surface of the input member cylindrical portion 202 has an annular first step portion 126 that is orthogonal to the axial direction S and faces the second axial direction S2, and an inner diameter portion of the first step portion 126. A cylindrical press-fit portion 127 extending from the first to the one side S1 in the axial direction S, an annular second step portion 128 disposed on the one S1 side in the axial direction S with respect to the press-fit portion 127, and the press-fit portion A female spline portion 129 disposed on one S1 side in the axial direction S with respect to 127, and a play that is disposed on the one S1 side in the axial direction S with respect to the female spline portion 129 and in which the first shaft 11 is loosely fitted. The fitting part 130 is included.

  The locked portion 122 and the press-fit portion 123 of the first shaft 11 are formed on the outer peripheral surface of the columnar small diameter portion 131. With respect to the axial direction S, the length of the small diameter portion 131 is shorter than the length of the female spline portion 129 of the input member 20. Thereby, when inserting the 1st shaft 11 in the input member 20, the male spline part 125 of the 1st shaft 11 can be engaged with the input member 20 ahead of the small diameter part 131. FIG.

The male spline portion 125 of the first shaft 11 is formed in the large diameter portion 132 of the first shaft 11. The large diameter portion 132 is adjacent to the small diameter portion 131 and has a larger diameter than the small diameter portion 131. A positioning step 124 is formed between the small diameter portion 131 and the large diameter portion 132.
The male spline part 125 of the first shaft 11 is arranged on the guide part 133 connected to the positioning step part 124 and on the one side S1 in the axial direction S with respect to the guide part 133, and the male spline part main body 134 having a constant outer diameter. Including.

The guide part 133 of the first shaft 11 serves as a guide when the male spline part main body 134 is inserted into the female spline part 129. The outer diameter of the guide part 133 becomes larger as it proceeds toward the one side S1 in the axial direction S.
Regarding the axial direction S, the male spline part 125 of the input member 20 is formed relatively long, and the press-fitting part 123 of the first shaft 11 is formed relatively short.

  A push nut 121 as a third connecting element is disposed so as to engage with both the first step portion 126 of the input member 20 and the locked portion 122 of the first shaft 11. As shown in FIG. 4, the push nut 121 is a thin sheet metal member, and includes an annular main body 135 and a plurality of tongue pieces 136 extended from the inner diameter portion of the main body 135. A plurality of (for example, four) tongue pieces 136 are arranged at equal intervals in the circumferential direction of the main body part 135, and are inclined with respect to the main body part 135.

  Referring to FIG. 3 again, the push nut 121 is externally fitted to the small diameter portion 131 of the first shaft 11. One side surface of the main body portion 135 of the push nut 121 is in contact with the first step portion 126 of the input member 20. Moreover, the front-end | tip as a free end of each tongue piece 136 of the push nut 121 is latched by the to-be-latched part 122 of the 1st shaft 11, and has faced the 2nd axial direction S2 side. This prevents the input member 20 from being detached from the first shaft 11 toward the other side S2 in the axial direction S.

The press-fit portion 122 of the input member 20 is formed on the inner peripheral surface of an annular extending portion 203 that extends radially inward from the input member tubular portion 202. In the extended portion 203, the first step portion 126 and the second step portion 128 are formed.
The press-fit portion 127 is lightly press-fitted and fixed to the press-fit portion 123 of the first shaft 11 by tight fitting. The press-fit portion 127 and the press-fit portion 123 form a tight fit portion 137 as a second connecting element that connects the first shaft 11 and the input member 20. Thereby, the 1st shaft 11 and the input member 20 are connected so that the accompanying rotation is possible.

  The female spline portion 129 of the input member 20 is formed on the inner peripheral surface of the intermediate portion of the cylindrical portion 202 of the input member 20. The female spline portion 129 is fitted to the male spline portion 125 of the first shaft 11 so as to be able to rotate together. The female spline portion 129 and the male spline portion 125 are fitted with no gap in the circumferential direction C. These spline portions 125 and 129 form a spline fitting portion 138 as a first connecting element for connecting the first shaft 11 and the input member 20.

Further, the extending portion 203 of the input member 20 is sandwiched between the push nut 121 and the positioning step portion 124 of the first shaft 11, and the input member 20 is axial with respect to the first shaft 11. It is made not to move to S.
With respect to the mounting direction D1 in which the first shaft 11 is mounted on the input member 20, the spline fitting portion 138, the tight fit portion 137, and the push nut 121 are arranged in this order. The mounting direction D1 is along the second axial direction S2.

The output member 22 is integrally formed using a single member as a whole, and includes an output member main body 221 and an output member cylindrical portion 222 disposed radially inward of the output member main body 221. Yes.
The output member 22 is rotatably supported by a distal end portion of an inner cylinder 93 (described later) of the second housing 52 via a third bearing 33.

The second shaft 12 that is the output shaft as the other of the pair of shafts is inserted into the output member cylindrical portion 222, so that the output member cylindrical portion 222 and the second shaft 12 can rotate together. It is connected.
Specifically, one end 12 a of the second shaft 12 is engaged with a locked portion 142 to which the push nut 141 is locked, a press-fit portion 143 that is press-fitted into the output member cylindrical portion 222, and the press-fit portion 143. An annular positioning step 144 arranged on the other side S2 in the axial direction S and extending radially outward with respect to the press-fit portion 143, and a male spline arranged on the other S2 side in the axial direction S with respect to the positioning step 144 Part 145.

  In addition, the inner peripheral surface of the output member cylindrical portion 222 has an annular first step portion 146 that is orthogonal to the axial direction S and faces the first axial direction S1, and an axial direction from the first step portion 146. A cylindrical press-fit portion 147 extending to the other S2 side of S, an annular second step portion 148 disposed on the other S2 side in the axial direction S with respect to the press-fit portion 147, and a press-fit portion 147 A female spline portion 149 disposed on the other S2 side in the axial direction S, and a loose fitting portion 150 disposed on the other S2 side in the axial direction S with respect to the female spline portion 149 and loosely fitted to the second shaft 12. Is included.

  The locked portion 142 and the press-fit portion 143 of the second shaft 12 are formed on the outer peripheral surface of the small diameter portion 151. The male spline portion 145 of the second shaft 12 is formed in the large diameter portion 152 of the second shaft 12. The large diameter portion 152 is adjacent to the small diameter portion 151 and has a larger diameter than the small diameter portion 151. A positioning step 144 is formed between the small diameter portion 151 and the large diameter portion 152.

The male spline portion 145 of the second shaft 12 is disposed on the other side S2 in the axial direction S with respect to the guide portion 153 that is continuous with the positioning step portion 144 of the second shaft 12, and has an outer diameter. A certain male spline body 154.
The guide portion 153 of the second shaft 12 serves as a guide when the male spline portion main body 154 is inserted into the female spline portion 149. The outer diameter of the guide portion 153 of the second shaft 12 increases as it advances toward the other side S2 in the axial direction S.

With respect to the axial direction S, the male spline part 145 is formed relatively long, and the press-fit part 143 is formed relatively short.
A push nut 141 as a third connecting element is disposed so as to engage with both the first step portion 146 of the output member 22 and the locked portion 142 of the second shaft 12. The push nut 141 has the same configuration as the push nut 121.

  The push nut 141 is fitted on the small diameter portion 151 of the second shaft 12. One side surface 135 a of the main body portion 135 of the push nut 141 is in contact with the first step portion 146 of the output member 22. Moreover, the front-end | tip 136a as a free end of each tongue piece 136 of the push nut 141 is latched by the to-be-latched part 142 of the 2nd shaft 12, and has faced the 1st axial direction S1 side. This prevents the output member 22 from being detached from the second shaft 12 toward the one side S1 in the axial direction S.

The press-fit portion 143 of the output member 20 is formed on the inner peripheral surface of an annular extending portion 223 that extends radially inward from the output member cylindrical portion 222. The extended portion 223 is formed with the first step portion 146 and the second step portion 148.
The press-fit portion 147 is lightly press-fitted and fixed to the press-fit portion 143 of the second shaft 12 by tight fitting. The press-fit portion 147 and the press-fit portion 143 form a tight fit portion 157 as a second connecting element that connects the second shaft 12 and the output member 22. Thereby, the 2nd shaft 12 and the output member 22 are connected so that the accompanying rotation is possible.

  The female spline part 149 of the output member 22 is formed on the inner peripheral surface of the output member cylindrical part 222 of the output member 22. The female spline part 149 is fitted to the male spline part 145 of the second shaft 12 so as to be able to rotate together. The female spline portion 149 and the male spline portion 15 are fitted with no gap in the circumferential direction C. These spline portions 145 and 149 form a spline fitting portion 158 as a first connecting element for connecting the second shaft 12 and the output member 22.

Further, the extending portion 223 of the output member 22 is sandwiched between the push nut 141 and the positioning step portion 144 of the second shaft 12, and the output member 22 is axial with respect to the second shaft 12. It does not move to S.
With respect to the mounting direction D2 in which the second shaft 12 is mounted on the output member 22, the spline fitting portion 158, the tight fit portion 157, and the push nut 141 are arranged in this order. The mounting direction D2 is along the first axial direction S1.

By providing the input member main body 201 and the inner ring 391 with the first concave and convex engaging portions 71, the input member 20 and the inner ring 391 can transmit power. In addition, since the second uneven engagement portion 72 is provided in each of the inner ring 391 and the output member 22, the inner ring 391 and the output member 22 can transmit power.
The first uneven engaging portion 71 is formed on the first convex portion 74 formed on the power transmission surface 73 as one end surface of the input member main body 201 and the first end surface 75 as one end surface of the inner ring 391. And a first recess 76 that engages with the first protrusion 74. The power transmission surface 73 and the first end surface 75 are opposed to each other in the axial direction S of the steering shaft 3.

The first convex portions 74 are formed at equal intervals over the entire circumference of the input member 20. The first recesses 76 are formed at equal intervals over the entire circumference of the inner ring 391.
Since the second axis B of the inner ring 391 is inclined with respect to the first axis A of the input member 20 and the output member 22, a part of the first protrusions 74 among the first protrusions 74. 74 and a part of the first recesses 76 of the first recesses 76 mesh with each other.

The number of first protrusions 74 is different from the number of first recesses 76. A differential rotation can be generated between the input member 20 and the inner ring 391 according to the difference between the number of the first protrusions 74 and the number of the first recesses 76.
The second concavo-convex engaging portion 72 is formed on the second convex portion 78 formed on the power transmission surface 77 as one end surface of the output member 22 and the second end surface 79 as the other end surface of the inner ring 391. And a second concave portion 80 that engages with the second convex portion 78. The power transmission surface 77 and the second end surface 79 are opposed to each other in the axial direction S of the steering shaft 3.

The second convex part 78 of the second concave / convex engaging part 72 has the same configuration as the first convex part 74, and the second concave part 80 has the same configuration as the first concave part 76. Have. Therefore, the detailed description of the second uneven engagement portion 72 is omitted.
The input member tubular portion 202 surrounds the opposing ends 11b and 12a of the first and second shafts 11 and 12, and can rotate the one end 12a of the second shaft 12 via the eighth bearing 38. I support it.

FIG. 5 is an enlarged view of the transmission ratio variable mechanism 5 of FIG. 2 and its surroundings. Referring to FIG. 5, the rotor 231 of the transmission ratio variable mechanism motor 23 includes a cylindrical rotor core 85 extending in the axial direction S, and a permanent magnet 86 fixed to the outer peripheral surface of the intermediate portion 85 c of the rotor core 85. It is out. The axial direction S is also the axial direction of the rotor 231.
On the inner peripheral surface of the rotor core 85, an inclined hole 91 is formed that has the second axis B as the central axis and is inclined with respect to the first axis A. The outer ring 392 of the raceway ring unit 39 is press-fitted and fixed in the inclined hole 91. As a result, the outer ring 392 and the rotor core 85 can be rotated together around the first axis A.

The rotor core 85 is supported at both ends by the second and fourth bearings 32 and 34. Specifically, the second bearing 32 is disposed between the inner peripheral surface of the one end portion 85 a of the rotor core 85 and the outer peripheral surface of the annular convex portion 92 formed on the inner diameter portion of one end of the first housing 51. Has been.
The fourth bearing 34 is disposed between the inner peripheral surface of the intermediate portion 85 c of the rotor core 85 and the outer peripheral surface of the distal end portion of the inner cylinder 93 of the second housing 52. A part of the inner cylinder 93 is disposed in the rotor core 85.

The stator 232 of the transmission ratio variable mechanism motor 23 is fixed to the inner peripheral surface of the outer diameter portion 87 of the first housing 51 by shrink fitting or the like.
The motor resolver 43 is disposed in the second housing 52. The motor resolver 43 includes a resolver rotor 107 and a resolver stator 108.
The resolver rotor 107 is fixed to the outer peripheral surface of the other end portion 85 b of the rotor core 85. The resolver stator 108 is press-fitted and fixed to the inner peripheral surface of the outer diameter portion 88 of the second housing 52.

6 is an enlarged view of the periphery of the torque sensor 44 of FIG. Referring to FIG. 6, torque sensor 44 detects torque acting between second and third shafts 12 and 13.
The torque sensor 44 is supported by one end of the third shaft 13 and the multipolar magnet 115 fixed to the intermediate portion of the second shaft 12, and is arranged in a magnetic field generated by the multipolar magnet 115 to be a magnetic circuit. And magnetic yokes 116 and 117, which are signal detection members as a pair of soft magnetic bodies.

Each of the magnetic yokes 116 and 117 is molded on a synthetic resin member 118. The synthetic resin member 118 is coupled to one end of the third shaft 13 so as to be able to rotate together.
The torque sensor 44 further includes an annular portion 112. The annular portion 112 has an annular shape as a whole, and a pair of magnetic flux collecting rings 119 and 120 as signal detecting members for inducing magnetic flux from the magnetic yokes 116 and 117, and between the magnetic flux collecting rings 119 and 120. It includes a Hall IC 160 as a signal detection member and a synthetic resin member 161 for molding the magnetism collecting rings 119 and 120 and the Hall IC 160.

The Hall IC 160 is for detecting the magnetic flux induced in the magnetism collecting rings 119 and 120.
The synthetic resin member 161 is held by the inner cylinder 93 of the second housing 52. The synthetic resin member 161 holds the outer peripheral surface of the outer ring of the fifth bearing 35 in cooperation with the connecting wall 94 that connects the outer diameter portion 88 of the second housing 52 and the inner cylinder 93.

A fifth bearing 35 is disposed on the other side S <b> 2 in the axial direction S with respect to the torque sensor 44. The fifth bearing 35 rotatably supports one end of the third shaft 13.
With the above configuration, magnetic flux is generated in the magnetic yokes 116 and 117 in accordance with the relative rotation amounts of the second and third shafts 12 and 13, and this magnetic flux is induced by the magnetic flux collecting rings 119 and 120. , Detected by the Hall IC 160. The torque detection signal of the Hall IC 160 is input to the control unit. In this way, the magnetic flux density corresponding to the torque applied to the second and third shafts 12 and 13 can be detected.

With reference to FIG. 2, the outer peripheral portion of the second shaft 12 and the inner peripheral portion of the third shaft 13 are supported by a sixth bearing 36 so as to be relatively rotatable. The end wall portion 61 of the third housing 53 supports the third shaft 13 via the seventh bearing 37 so as to be rotatable.
In the vehicle steering apparatus 1 having the above-described schematic configuration, the connection between the input member 20 and the first shaft 11 is performed as follows. That is, first, as shown in FIG. 7A, a single input member 20 and the first shaft 11 are prepared, and the small diameter portion 131 of the first shaft 11 faces the input member 20 side. Make both face each other.

  Next, as shown in FIG. 7B, the first shaft 11 is moved in the mounting direction D <b> 1 with respect to the input member 20, and the first shaft 11 is moved to the input member cylindrical portion 202 of the input member 20. Insert. As a result, the large-diameter portion 132 of the first shaft 11 is loosely fitted to the loose fitting portion 130 of the input member 20. Further, the guide portion 133 of the male spline portion 125 of the large diameter portion 132 of the first shaft 11 engages with the female spline portion 129. Thereby, both tooth parts are mutually arrange | positioned in the circumferential direction, and both phase is match | combined. Thereafter, the male spline part main body 134 of the male spline part 125 engages with the female spline part 129.

In a state where the male spline part 125 and the female spline part 129 are fitted, the first shaft 11 is further moved in the mounting direction D1. Thereby, as shown in FIG. 7C, the press-fit portion 123 of the first shaft 11 is press-fitted into the press-fit portion 127 of the input member 20.
As shown in FIG. 7D, the push nut 121 is inserted through the first shaft 11 in a state where the positioning step portion 124 of the first shaft 11 is in contact with the second step portion 128 of the input member 20. To do. Thereby, the front end of each tongue piece 136 of the push nut 121 is locked to the locked portion 122 of the first shaft 11, and one side surface of the main portion 135 of the push nut 121 is fixed to the first portion of the input member 20. It abuts on the stepped portion 126. Thereby, the connection between the first shaft 11 and the input member 20 is completed.

Further, the connection between the output member 22 and the second shaft 12 is performed as follows. That is, first, as shown in FIG. 8A, a single output member 22 and the second shaft 12 are prepared, and the small diameter portion 151 of the second shaft 12 faces the output member 22 side. Make both face each other.
Next, as shown in FIG. 8B, the second shaft 12 is moved in the mounting direction D <b> 2 with respect to the output member 22, and the second shaft 12 is moved to the output member cylindrical portion 222 of the output member 22. Insert. As a result, the small diameter portion 151 of the second shaft 12 is press-fitted into the press-fit portion 147 of the output member 22. When the second shaft 12 is further moved in the mounting direction D <b> 2, the large diameter portion 152 of the second shaft 12 is loosely fitted to the loose fitting portion 150 of the output member 22. Further, the guide portion 153 of the male spline portion 145 of the large diameter portion 152 of the second shaft 12 engages with the female spline portion 149. Thereby, both tooth parts are mutually arrange | positioned in the circumferential direction, and both phase is match | combined.

Thereafter, as shown in FIG. 8C, the male spline portion main body 154 engages with the female spline portion 149. In this state, the second shaft 12 is further moved in the mounting direction D2. As a result, the positioning step 144 of the second shaft 12 contacts the second step 148 of the output member 22 as shown in FIG.
In this state, the push nut 141 is inserted through the second shaft 12. As a result, the tip of each tongue piece 136 of the push nut 141 is locked to the locked portion 142 of the second shaft 12, and the one side surface 135 a of the main portion 135 of the push nut 141 is connected to the first side of the output member 22. It abuts on the step 146. Thereby, the connection between the second shaft 12 and the output member 22 is completed.

Referring to FIG. 1, the vehicle steering apparatus 1 having the above-described schematic configuration drives the transmission ratio variable mechanism motor 23 to drive the transmission ratio variable mechanism 5 when the vehicle is traveling at a relatively low speed. By changing the transmission ratio θ2 / θ1, the function of assisting the driver's steering by amplifying the steering angle θ1 with respect to the turning angle θ2 can be exhibited.
When the vehicle is traveling at a relatively high speed, the transmission ratio variable mechanism motor 23 is driven to change the transmission ratio θ2 / θ1 in the variable transmission ratio mechanism 5, thereby controlling the vehicle stability control ( Attitude stability control).

  As described above, according to the present embodiment, the tight fit portions 137 and 157 are respectively connected to the connection between the first shaft 11 and the input member 20 and the connection between the second shaft 12 and the output member 22. Provided. Thereby, the clearance of the circumferential direction C between the 1st shaft 11 and the input member 20 and the clearance of the circumferential direction C between the 2nd shaft 12 and the output member 22 can each be closed. Therefore, it is possible to prevent rattling between the first shaft 11 and the input member 20, and it is possible to prevent rattling between the second shaft 12 and the output member 22.

  Further, spline fitting portions 138 and 158 are provided for the connection between the first shaft 11 and the input member 20 and the connection between the second shaft 12 and the output member 22, respectively. Thus, even when a large torque is input between the first shaft 11 and the input member 20 and between the second shaft 12 and the output member 22, it cooperates with the tight fit portions 137 and 157. Therefore, a large torque can be transmitted by the corresponding spline fitting portions 138 and 158, and a sufficient torque transmission capacity can be secured.

Push nuts 121 and 141 are provided, and the input member 20 is sandwiched between the push nut 121 and the positioning step portion 124 of the first shaft 11, and the output member 22 is connected to the push nut 141 and the second shaft 12. It is sandwiched between the positioning step portion 144.
Thereby, it is possible to reliably prevent the input member 20 from detaching from the first shaft 11 and the output member 22 from detaching from the second shaft 12. In addition, since the tight fit portions 137 and 157 do not need to transmit a large torque, the overall length can be shortened, and the push nuts 121 and 141 are thin. As a result, the vehicle steering device 1 can be reduced in size, weight, and cost of parts through shortening the overall length of the vehicle steering device 1.

Further, with respect to the mounting direction D1, the spline fitting portion 138, the tight fit portion 137, and the push nut 121 are arranged in this order. Similarly, with respect to the mounting direction D2, the spline fitting portion 158, the tight fit portion 157, and the push nut 141 are arranged in this order.
Thereby, with respect to the mounting directions D1 and D2, the corresponding spline fitting portions 138 and 158 are arranged on the upstream side of the corresponding first and second shafts 11 and 12, respectively. Thereby, when attaching the input member 20 and the output member 22 to the corresponding 1st and 2nd shafts 11 and 12, it can make it easy to visually recognize the spline fitting part 138,158. Thereby, it is possible to easily perform phase alignment in the circumferential direction C of the first and second shafts 11 and 12 corresponding to the input member 20 and the output member 22.

  Further, the extending portion 203 of the input member 20 is sandwiched between the push nut 121 and the positioning step portion 124 of the first shaft 11. Thereby, it is possible to reliably restrict the input member 20 from moving in the axial direction S with respect to the first shaft 11. Similarly, the extending portion 223 of the output member 22 is sandwiched between the push nut 141 and the positioning step portion 144 of the second shaft 12. Thereby, it is possible to reliably restrict the output member 22 from moving in the axial direction S with respect to the second shaft 12.

  Further, by fixing the input member 20 and the first shaft 11 by light press-fitting by the tight fit portion 137, the shift of the coaxiality between the first shaft 11 and the input member 20 can be reduced. Positioning can be performed with high accuracy. Similarly, by fixing the output member 22 and the second shaft 12 by light press-fitting by the tight fit portion 157, the shift of the coaxiality between the second shaft 12 and the output member 22 can be reduced. Can be positioned with high accuracy.

  Further, by spline-fitting the input member 20 and the first shaft 11 with the spline fitting portion 138, even if a large torque acts, the input member 20 and the first shaft 11 can be reliably connected. It is possible to suppress the relative phase (position in the circumferential direction) from shifting. Thereby, in the steering neutral state, it can suppress that the phase of the 1st shaft 11 and the steering member 2 shifts | deviates, and it can prevent that an uncomfortable feeling is produced in steering.

  Similarly, by spline fitting the output member 22 and the second shaft 12 with the spline fitting portion 158, even if a large torque is applied, the output member 22 and the second shaft 12 can be reliably connected. It is possible to prevent the relative phase (position in the circumferential direction) from shifting. Thereby, it can suppress that the phase of the 2nd shaft 12 and the steering member 2 slip | deviates in a steering neutral state, and it can prevent that an uncomfortable feeling arises in steering.

The present invention is not limited to the contents of the above-described embodiment, and various modifications can be made within the scope of the claims.
For example, the spline fitting portion 138, the tight fit portion 137, and the push nut 121 between the first shaft 11 and the input member 20 may be eliminated. Alternatively, the spline fitting portion 158, the tight fit portion 157, and the push nut 141 between the second shaft 12 and the output member 22 may be eliminated.

Further, the first shaft 11 and the input member 20 may be serrated by providing a serration fitting portion instead of the spline fitting portion 138. Further, by providing a serration fitting portion instead of the spline fitting portion 158, the second shaft 12 and the output member 22 may be serrated.
Further, a loose fit portion may be provided instead of the tight fit portion 137. By such light press fitting, the coaxiality between the first shaft 11 and the input member 20 in the loose fit portion can be further improved between the first shaft 11 and the input member 20. Similarly, a loose fit portion may be provided instead of the tight fit portion 157. Such light press fitting can further improve the coaxiality between the second shaft 12 and the output member 22 in the loose fit portion between the second shaft 12 and the output member 22.

It is a mimetic diagram showing a schematic structure of a steering device for vehicles provided with a transmission ratio variable mechanism 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. FIG. 3 is an enlarged view of the vicinity of opposing ends of a first shaft and a second shaft in FIG. 2. It is a perspective view of a push nut. FIG. 3 is an enlarged view of a transmission ratio variable mechanism in FIG. 2 and its surroundings. It is an enlarged view of the periphery of the torque sensor of FIG. (A)-(D) are sectional drawings which show the process of a connection with a 1st shaft and an input member, respectively. (A)-(D) are sectional drawings which respectively show the process of a connection of a 2nd shaft and an output member.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Vehicle steering device, 2 ... Steering member, 4L, 4R ... Steering wheel, 5 ... Transmission ratio variable mechanism, 11 ... 1st shaft (input shaft), 11b ... The other end part (of 1st shaft) ( (Shaft end), 12 ... second shaft (output shaft), 12a ... (second shaft) one end (shaft end), 20 ... input member, 22 ... output member, 121,141 ... push nut (third) , 124, 144 ... positioning step part, 131, 151 ... small diameter part, 132, 152 ... large diameter part, 138, 158 ... spline fitting part (first connection element), 137, 157 ... tight fit Part (second connecting element), 202, 222 ... cylindrical part, 203, 223 ... extension part, 391 ... inner ring (intermediate member), A ... first axis, B ... second axis, D1, D2 ... Mounting direction (direction in which the shaft corresponding to the corresponding cylindrical member is mounted), 1 ... steering angle, .theta.2 ... turning angle, .theta.2 / .theta.1 ... transmission ratio.

Claims (3)

A transmission ratio variable mechanism capable of changing the transmission ratio, which is the ratio of the turning angle of the steered wheels to the steering angle of the steering member,
The transmission ratio variable mechanism is fitted with a pair of shafts having a central axis on a first axis, one of which constitutes an input shaft and the other of which constitutes an output shaft, so as to be able to rotate together with each of the pair of shafts. A pair of cylindrical members, one of which constitutes an input member and the other of which constitutes an output member, and the pair of cylindrical members which are coupled to each other so as to be differentially rotatable, and which are inclined with respect to the first axis. An intermediate member rotatable about an axis,
Comprising first, second and third connecting elements for connecting at least one of the pair of shafts and the corresponding cylindrical member;
The first connecting element includes a spline fitting portion or a serration fitting portion,
The second connecting element includes a loose fit portion or a tight fit portion,
The third connection element includes a push nut that is locked to at least one of the pair of shafts and prevents the corresponding cylindrical member from being detached.   The first connection element, the second connection element, and the third connection element are arranged in this order in the direction in which the shaft corresponding to the corresponding cylindrical member is mounted. Vehicle steering system. The at least one of the pair of shafts according to claim 2, wherein the at least one of the pair of shafts is a small diameter portion provided at a shaft end, a large diameter portion adjacent to the small diameter portion, and an annular shape formed between the large diameter portion and the small diameter portion. And the push nut is fitted to the small diameter portion,
The corresponding cylindrical member includes a cylindrical portion that is spline-fitted or serrated to the large-diameter portion, and extends radially inward from the cylindrical portion, and loosely or tight-fit to the outer periphery of the small-diameter portion. A ring-shaped extension part fitted,
The vehicle steering apparatus, wherein the extending portion is sandwiched between the push nut and the positioning step portion.

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