JP2009179108A - Vehicular steering unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vehicular steering unit capable of improving durability by suppressing fretting wear in contact parts during linear traveling. <P>SOLUTION: A transfer ratio variable mechanism includes an inner wheel 391 as an middle member which intervenes between an input member 20 and an output member, and allows differential rotation of both members. First power transmission surfaces 70, 71 of the input member 20 and the inner wheel 391 include first regions P1, Q1 fitted to each other when the steering angle is within a predetermined angular range including a steering center, and second regions P2, Q2 outside the first regions P1, Q1. The rigidity of a first protrusion part 651 and a first recess part 661 in the first regions P1, Q1 is made relatively higher. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a vehicle steering apparatus.

In order to reduce the backlash between the gears that transmit the power of the steering assisting electric motor to be smaller than the remaining region in the vicinity of the steering neutral position, for example, it is possible to reduce noise by biasing a part of the teeth. It has been proposed (see, for example, Patent Document 1).
JP 2004-182013 A

On the other hand, when a so-called Coriolis movement mechanism is used as the transmission ratio variable mechanism installed in the vehicle, there is a problem that the meshing portions of the members meshing with each other quickly wear in the most straight running state in the traveling state of the vehicle. is there.
The present invention has been made under such a background, and an object of the present invention is to provide a vehicle steering apparatus capable of improving durability by suppressing fretting wear at locations in contact with each other during straight traveling. Is to provide.

  In order to achieve the above object, the present invention provides a variable transmission ratio mechanism capable of changing a transmission ratio that is a ratio of a turning angle (θ2) of a wheel (4L, 4R) to a steering angle (θ1) of a steering member (2). (5), the transmission ratio variable mechanism is connected to the steering member and rotatable about the first axis (A), and is connected to the wheel and rotated about the first axis. A possible output member (22) and an intermediate member (391) interposed between the input member and the output member to connect the two members so as to allow differential rotation of both members, The input member and the intermediate member are rotatable about a second axis (B) inclined with respect to one axis, and the input member and the intermediate member can be fitted to each other (651, 6510, 651A, 652, 661). 6610, 661A, 662) an annular first power transmission surface (7 0, 71), and the output member and the intermediate member each have an annular second power transmission surface (72, 73) having a fitting portion (681, 682, 691, 692) that can be fitted to each other. In addition, each of the first power transmission surface and the second power transmission surface includes a first region (P1, Q1; U1, which fits each other when the steering angle is within a predetermined angle range including the steering center). W1) and a second region (P2, Q2; U2, W2) that are fitted to each other when the steering angle is outside the predetermined angle range, and the fitable portion (651) in the first region , 6510, 651A, 661, 6610, 661A, 681, 691) are made harder than the fitting portions (652, 662, 682, 692) in the second region. .

According to the present invention, since the fitting portion of the first region that is fitted during straight running is relatively hard, the occurrence of fretting wear due to minute vibrations can be suppressed.
It is preferable that the material of the matable part in the first region and the material of the matable part in the second region are different from each other (Claim 2), specifically, the fitting of the first region. The matable part may contain ceramics (claim 3). Since ceramics have high hardness, fretting wear can be remarkably reduced. Examples of ceramics include silicon nitride, silicon carbide, zirconia, and alumina.

Moreover, the fitting force of the fitting part of the said 1st area | region may be made larger than the fitting force of the fitting part of a 2nd area | region (Claim 4). In this case, fretting wear can be further reduced by suppressing looseness of fitting.
Specifically, at least one of the first power transmission surface and the second power transmission surface that can be fitted includes a convex portion and a concave portion that are fitted to each other, and a convex portion (651, 651 in the first region). 651A, and the recesses (661, 661A) in the first region are stronger than the protrusions (652) in the second region and the recesses (662) in the second region. As described above, the convex portion (651A) of the first region is made larger than the convex portion (652) of the second region, or the concave portion (661A) of the first region is made concave portion (662) of the second region. There is a case where it is set to be at least one of smaller than (Claim 5).

Moreover, the said convex part is formed of the roller member (311A, 312), and the diameter (R1) of the roller member (311A) forming the convex part of the first region is different from the convex part (652) of the second region. The diameter (R2) of the roller member (312) to be formed may be larger (Claim 6). In this case, manufacture is easy.
Note that, in the above, reference numerals 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. Giving and turning. The vehicle steering apparatus 1 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.

  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.

  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 of the first shaft 11 and one end of the second shaft 12 are coupled via a transmission ratio variable mechanism 5 so as to be differentially rotatable. 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 13 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 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 an orbiting ring unit 39 interposed therebetween.

  The input member 20 is connected to the steering member 2 and the first shaft 11 so as to be coaxial and rotatable together, and the output member 22 is connected to the second shaft 12 and coaxially rotatable. Has been. 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 track ring unit 39 includes an inner ring 391 as a first track ring that provides an intermediate member, an outer ring 392 as a second track ring, and rolling elements 393 such as balls interposed between the inner ring 391 and the outer ring 392. The four-point contact bearing is configured. The rolling element 393 may be a cylindrical roller, a needle roller, or a tapered roller. Moreover, a single row or a double row may be sufficient. When double rows are used, the inner ring 391 can be prevented from falling. A double row angular bearing can be illustrated as a double row thing.

  The inner ring 391 functions as an intermediate member that connects the input member 20 and the output member 22 so as to be differentially rotatable. The inner ring 391 and the outer ring 392 have a second axis B as a central axis inclined with respect to the first axis A. The inner ring 391 is rotatably supported by an outer ring 392 as a second raceway ring via a rolling element 393, so that the inner ring 391 can rotate around the second axis B and drives the outer ring 392. As the transmission ratio variable mechanism motor 23, which is an electric motor as an actuator for driving, 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 is disposed radially outward with the first axis A of the bearing ring unit 39 as the center. 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, for example, a brushless motor that is coaxially disposed with the steering shaft 3, and includes a rotor 231 that holds the raceway ring unit 39, a housing 24 that surrounds the rotor 231 and that serves as a steering column. And a stator 232 fixed to the main body. The rotor 231 rotates around the first axis A.

  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 that detects torque transmitted between the second shaft 12 and the third shaft 13; a steering assist motor 25 as a steering assist actuator; a steering assist motor 25; A speed reduction mechanism 26 interposed between the shaft 13 and the shaft 13 is included.

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 gear 28 as a driven gear. The speed reduction mechanism 26 is not limited to the worm gear mechanism, and other gear mechanisms such as a parallel shaft gear mechanism using a spur gear or a helical gear may be used.

The transmission ratio variable mechanism 5 and the steering assist force applying mechanism 19 are provided in a housing 24 and are accommodated in the 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 means for detecting the rotation angle of the transmission ratio variable mechanism motor 23, a torque sensor 44 as a torque detection means, and a turning angle sensor 45. A vehicle speed sensor 46 and a yaw rate sensor 47 are connected to each other.
Signals from the sensors 42 to 47 are input to the control unit 29. Specifically, a signal regarding the rotation angle of the first shaft 11 is input from the steering angle sensor 42 as a value corresponding to the steering angle θ1 that is the operation amount from the straight position of the steering member 2. Further, the motor resolver 43 receives a signal about the rotation angle θr of the rotor 231 of the transmission ratio variable mechanism motor 23.

  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 drive of the transmission ratio variable mechanism motor 23 and the steering assist motor 25 based on signals and the like input from the sensors 42 to 47.
With the above configuration, the output of the transmission ratio variable mechanism 5 is transmitted to the steering mechanism 10 via the steering assist force applying mechanism 19. More 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 the steering assist force applying mechanism 19 of the steering assist force applying mechanism 19 is changed from the output member 22. Is transmitted to the second shaft 12. The steering torque transmitted to the second shaft 12 is transmitted to the torsion bar 14 and the third shaft 13, and together with the output from the steering assist motor 25, is transmitted to the steering mechanism 10 via the intermediate shaft 8 or the like. The

  FIG. 2 is a cross-sectional view showing a more specific configuration of the main part of FIG. Referring to FIG. 2, the housing 24 is formed by, for example, forming a metal such as an aluminum alloy into a cylindrical shape, and includes first to third housings 51 to 53. In the housing 24, first to eighth bearings 31 to 38 are accommodated. Each of the first to fifth bearings 31 to 35 and the seventh to eighth bearings 37 to 38 is a rolling bearing such as an angular ball bearing, and the sixth bearing 36 is a rolling bearing such as a needle roller bearing. It is.

  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 a motor housing that houses the transmission ratio variable mechanism motor 23. It is composed. One end of the first housing 51 is covered with an end wall 54. One end of the first housing 51 and the end wall 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 and a resolver housing that houses the motor resolver 43. The second housing 52 accommodates a bus bar 99 described later of the transmission ratio variable mechanism motor 23 and a lock mechanism 58 for locking the rotor 231 of the transmission ratio variable mechanism motor 23. 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 transmission ratio variable mechanism 5 of FIG. 2 and its surroundings. Referring to FIG. 3, input member 20, output member 22 and inner ring 391 of variable transmission ratio mechanism 5 each have an annular shape.

The input member 20 includes an input member main body 201 and a cylindrical member 202 that is disposed radially inward of the input member main body 201 and is connected to the input member main body 201 so as to be able to rotate together.
The first shaft 11 is connected to the tubular member 202 so as to be able to rotate along with the tubular member 202 by being inserted through the insertion hole 202 a of the tubular member 202.
The second shaft 12 is connected to the output member 22 so as to be able to rotate along with the output member 22 by passing through the insertion hole 22 a of the output member 22.

Opposing end portions 11 a and 12 a of the first shaft 11 and the second shaft 12 are supported coaxially and relatively rotatably by a support mechanism 133. The support mechanism 133 includes the cylindrical member 202 described above and the eighth bearing 38. That is, the cylindrical member 202 constitutes a part of the input member 20 and a part of the support mechanism 133.
The cylindrical member 202 surrounds the opposing end portions 11a and 12a of the first and second shafts 11 and 12, respectively. One end of the cylindrical member 202 faces the first bearing 31 in the radial direction. The other end of the cylindrical member 202 is opposed to the opposed end portion 12a of the second shaft 12 in the radial direction.

A bearing holding hole 109 is formed at the other end of the cylindrical member 202, and the opposed end portion 12 a of the second shaft 12 is inserted into the bearing holding hole 109. An eighth bearing 38 is interposed between the opposed end portion 12 a of the second shaft 12 and the bearing holding hole 109, and allows relative rotation between the cylindrical member 202 and the second shaft 12.
In addition, while connecting the cylindrical member 202 to the opposing end part 12a of the 2nd shaft 12 so that accompanying rotation is possible, the 8th bearing 38 is connected with the opposing end part 11a of the cylindrical member 202 and the 1st shaft 11. It may be interposed between them.

  An inner ring 391 as an intermediate member is disposed radially outward of the cylindrical member 202. The outer ring 392 is held in an inclined hole 63 formed in the inner peripheral portion 233 of the rotor 231 of the transmission ratio variable mechanism motor 23 so as to be able to rotate together. The outer ring 392 and the rotor 231 rotate along the first axis A. The inclined hole 63 has the second axis B as the central axis. As the rotor 231 rotates around the first axis A, the race ring unit 39 performs Coriolis motion.

The outer ring 392 of the bearing ring unit 39 connects the input member 20 and the output member 22 so as to be differentially rotatable, and the inner ring 391 is connected so as to be rotatable together with the rotor 231 of the transmission ratio variable mechanism motor 23. May be. In this case, the race ring unit 39 is an inner ring support type.
FIG. 4 is a side view showing a part of the transmission ratio variable mechanism 5 in cross section. Referring to FIGS. 3 and 4, input member main body 201 and inner ring 391 have annular first power transmission surfaces 70 and 71 that are opposed to each other in the axial direction S of steering shaft 3. The first power transmission surface 70 of the input member main body 201 is provided with first convex portions 651 and 652 as fitting portions, and a first power transmission surface 71 formed of an end surface of an inner ring 391 as an intermediate member. Are provided with first concave portions 661 and 662 as fitting-capable portions. The input member main body 201 and the inner ring 391 can transmit power by engaging the first convex portions 651 and 652 with the first concave portions 661 and 662.

  Referring to FIG. 4, the output member 22 and the inner ring 391 have annular second power transmission surfaces 72 and 73 that face each other in the axial direction S of the steering shaft 3. Referring to FIGS. 4 and 11, the second power transmission surface 72 of the output member 22 is provided with second convex portions 681 and 682 as fitting portions, and other than the inner ring 391 as an intermediate member. The second power transmission surface 73 formed of an end surface is provided with second recesses 691 and 692 as a fitting possible portion. The second convex portions 681 and 682 and the second concave portions 691 and 692 mesh with each other, so that the output member 22 and the inner ring 391 can transmit power.

  Referring to FIG. 5, a plurality of grooves 301 extending in the radial direction of the first power transmission surface 70 are radially arranged on the annular first power transmission surface 70 of the input member main body 201. They are arranged at equal intervals in the circumferential direction of the transmission surface 70. Each groove 301 is fitted with conical (or cylindrical) roller members 311 and 312. Half portions of the roller members 311 and 312 protrude from the groove 301, and the protruding half portions constitute first convex portions 651 and 652.

On the other hand, on the annular first power transmission surface 71 of the inner ring 391, a plurality of first recesses 661, 662 extending in the radial direction of the first power transmission surface 71 are radially arranged to form the first power transmission surface. 71 are arranged at equal intervals in the circumferential direction. The first convex portions 651 and 652 and the first concave portions 661 and 662 have substantially the same shape.
As shown in FIG. 6A, the first convex portions 651, 652 are arranged at equal intervals in the circumferential direction of the first power transmission surface 70. As shown in FIG. 6B, the first concave portions 661, 662 are The first power transmission surface 71 is arranged at equal intervals in the circumferential direction. Each of the first power transmission surfaces 70 and 71 includes first regions P1 and Q1 that are fitted to each other when the steering angle is within a predetermined angle range including the steering center, and the steering angle is outside the predetermined angle range. And the second regions P2 and Q2 that are fitted to each other.

The center P10 of the first region P1 of the first power transmission surface 70 and the center Q10 of the first region Q1 of the first power transmission surface 71 are in phase with each other when the steering angle is at the steering center. It has become.
In the 1st power transmission surface 70, the 1st convex part 651 (for example, 3-5 pieces) in the 1st field P1 is made harder than the 1st convex part 652 in the 2nd field P2. . Therefore, as the roller member 311 for constituting the first convex portion 651 in the first region P1, a material having relatively high hardness is used, and the first member in the second region P2 is used. As the roller member 312 for constituting the convex portion 652, a material having relatively low hardness is used. When ceramics are used as the roller member 311, for example, bearing steel or stainless steel having a lower hardness than ceramics can be used as the roller member 312. Examples of ceramics include silicon nitride, silicon carbide, zirconia, and alumina. As shown in FIG. 5, the roller members 311 and 312 may be tapered rollers having a diameter reduced toward the radially inner side of the input member 20 or cylindrical rollers.

  Moreover, in the 1st power transmission surface 71, the 1st recessed part 661 (for example, 3-5 pieces) in the 1st area | region Q1 is made harder than the 2nd recessed part 662 in the 2nd area | region Q2. . Therefore, the inner ring 391 is configured by combining the inner ring main body 391A and the high hardness member 391B. A material with relatively high hardness is used as the high hardness member 391B, and a material with relatively low hardness is used as the inner ring main body 391A. When ceramics are used as the high-hardness member 391B, for example, bearing steel or stainless steel having a hardness lower than that of ceramics can be used as the inner ring main body 391A. Examples of ceramics include silicon nitride, silicon carbide, zirconia, and alumina.

In the first power transmission surface 71, the high hardness member 391B constitutes the first region Q1, and the first recess 661 of the first region Q1 formed in the high hardness member 391B is the first region Q1. The power transmission surface 71 is harder than the first recess 662 of the second region Q2 formed by the inner ring main body 391A.
The total number of the first convex portions 651 and 652 is, for example, 38. The total number of the first concave portions 661 and 662 is different from the total number of the first convex portions 651 and 652. A differential rotation can be generated between the input member main body 201 and the inner ring 391 according to the difference between the total number of the first convex portions 651 and 662 and the total number of the first concave portions 661 and 662.

  Since the second axis B of the inner ring 391 is inclined at a predetermined angle θ with respect to the first axis A of the input member 20, some of the first protrusions 651 and 652 are the first protrusions. And only a part of the first recesses of the first recesses 661 and 662 mesh with each other. For example, when the vehicle is running straight, as shown in FIG. 7, the first convex portion 651 and the first concave portion 661 both having high hardness mesh with each other.

  5 and 7, the shapes of the groove 301 and the first recesses 661 and 662 are shown in a simplified manner, but actually, as shown in FIG. 8, the cross-sectional shapes of the groove 301 and the first recess 661 are shown. Is formed in a Gothic arc shape (a shape in which two arcs having the same radius and different centers are connected). In this case, the roller member 311 constituting the first convex portion 651 is supported by the groove 301 and the first concave portion 661 in a four-point contact state.

  Further, a grease reservoir 800 made of, for example, a groove is provided at the bottom of the groove 301 and the bottom of the first recess 661. In this case, grease can be sufficiently supplied from the grease reservoir 800 to the contact area between the roller member 311 and the groove 301 and the first recess 661, and wear and seizure of the contact area can be prevented over a long period of time. Can do. The grease reservoir 800 can be provided by arbitrarily setting the shape, depth, etc., as long as the position avoids the contact area. Although not shown, the same configuration as that of the first recess 661 is adopted for the first recess 662.

  Referring to FIG. 9, a plurality of grooves 302 extending in the radial direction of the second power transmission surface 72 are arranged radially on the annular second power transmission surface 72 of the output member 22 to provide the second power transmission. They are arranged at equal intervals in the circumferential direction of the surface 72. Each of the grooves 302 is fitted with conical (may be cylindrical) roller members 321 and 322. Half portions of the roller members 321 and 322 project from the groove 302, and the projecting halves constitute second convex portions 681 and 682.

On the other hand, on the annular second power transmission surface 73 of the inner ring 391, a plurality of second recesses 691 and 692 extending in the radial direction of the second power transmission surface 73 are radially arranged to form the second power transmission surface. 73 are arranged at equal intervals in the circumferential direction. The second convex portions 681, 682 and the second concave portions 691, 692 have substantially the same shape.
As shown in FIG. 10A, the second convex portions 681, 682 are arranged at equal intervals in the circumferential direction of the second power transmission surface 72, and as shown in FIG. 10B, the second concave portions 691, 692 are The second power transmission surface 73 is arranged at equal intervals in the circumferential direction. Each of the second power transmission surfaces 72 and 73 includes first regions U1 and W1 that are fitted to each other when the steering angle is within a predetermined angle range including the steering center, and the steering angle is outside the predetermined angle range. And the second regions U2 and W2 that are fitted to each other.

The center U10 of the first region U1 of the second power transmission surface 72 and the center W10 of the first region W1 of the second power transmission surface 73 are in phase with each other when the steering angle is at the steering center. It has become.
In the 2nd power transmission surface 72, the 2nd convex part 681 (for example, 3-5 pieces) in the 1st field U1 is made harder than the 2nd convex part 682 in the 2nd field U2. . Therefore, as the roller member 321 for configuring the second convex portion 681 in the first region U1, a material having relatively high hardness is used, and the second member in the second region U2 is used. As the roller member 322 for constituting the convex portion 682, a material having relatively low hardness is used. When ceramics are used as the roller member 321, for example, bearing steel or stainless steel having a hardness lower than that of ceramics can be used as the roller member 322. Examples of ceramics include silicon nitride, silicon carbide, zirconia, and alumina. As shown in FIG. 9, the roller members 321 and 322 may be tapered rollers having a diameter reduced toward the radially inner side of the output member 22 or may be cylindrical rollers.

  In the second power transmission surface 73, the second recesses 691 (for example, 3 to 5) in the first region W1 are harder than the second recesses 692 in the second region W2. . Therefore, the inner ring 391 is configured by combining the inner ring main body 391A and the high hardness member 391C. A material with relatively high hardness is used as the high hardness member 391C, and a material with relatively low hardness is used as the inner ring main body 391A. Specifically, when ceramics are used as the high-hardness member 391C, for example, bearing steel or stainless steel having lower hardness than ceramics can be used as the inner ring main body 391A.

In the second power transmission surface 73, the high hardness member 391C constitutes the first region W1, and the second recess 691 of the first region W1 formed in the high hardness member 391C is the second region W1. The power transmission surface 73 is harder than the second recess 692 in the second region W2 formed by the inner ring main body 391A.
The relationship between the total number of the second convex portions 681 and 682 and the total number of the second concave portions 691 and 692 may be different from each other, for example, 38 and 40, or may be the same as each other. May be.

  Since the second axis B of the inner ring 391 is inclined at a predetermined angle θ with respect to the first axis A of the output member 22, some of the second convex portions 681 and 682 are part of the second convex portion. And only some of the second recesses 691 and 692 mesh with each other. For example, in a straight traveling state of the vehicle, as shown in FIG. 11, the second convex portion 681 and the second concave portion 691 both having high hardness mesh with each other.

9 and 11, the shapes of the groove 302 and the second recesses 691 and 692 are shown in a simplified manner, but in actuality, the cross-sectional shapes of the groove 301 and the first recess 661 shown in FIG. 8 are the same. A Gothic arc shape is formed, and a grease reservoir 800 is provided.
Examples of the ceramic used for the roller members 311 and 321 and the high hardness members 391B and 391C in the first regions P1 and U1 include silicon carbide, silicon nitride, zirconia, and alumina.

  Referring to FIG. 3 again, 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 rotor core 85. The transmission ratio variable mechanism 5 and the torque sensor 44 are accommodated inside the rotor core 85 in the radial direction. By the rotor core 85, both the first convex portions 651 and 652 and the first concave portions 661 and 662, and the second convex portions 681 and 682 and the second concave portions 691 and 692 of the transmission ratio variable mechanism 5 are arranged on the entire circumference. And the torque sensor 44 is surrounded over the entire circumference (in FIG. 3, the first convex portion 651, the first concave portion 661, the second convex portion 681, and the second concave portion). Only 691 is shown.) By housing the transmission ratio variable mechanism 5 and the torque sensor 44 in the rotor core 85, the length of the housing 24 with respect to the axial direction S can be shortened. As a result, an impact absorbing stroke for absorbing the impact of the secondary collision of the vehicle. Can be secured for a long time. Further, it is possible to secure an arrangement space for a tilt / telescopic mechanism (not shown) provided adjacent to the housing 24.

Examples of the material of the rotor core 85 include steel materials, aluminum alloys, clad materials, and resin materials. When a clad material that is a composite material in which a plurality of kinds of metals are bonded together is used, resonance can be suppressed. When a resin material is used for at least a part of the rotor core 85, the rotor inertia can be reduced by reducing the weight.
A retained hole 87 is formed at one end of the rotor core 85. An annular bearing holding portion 88 is provided inside the held hole 87 in the radial direction. The bearing holding portion 88 is disposed on an annular convex portion 89 formed on the inner peripheral side of one end of the first housing 51. Since the second bearing 32 is interposed between the held hole 87 and the bearing holding portion 88, one end of the rotor core 85 is rotatably supported by the first housing 51.

  A held hole 90 is formed in an intermediate portion of the rotor core 85. An annular bearing holding portion 91 is provided inside the held hole 90 in the radial direction. The bearing holding portion 91 is disposed in an annular extending portion 92 formed on the inner peripheral side of one end of the second housing 52. The annular extending portion 92 has a cylindrical shape extending from the partition wall portion 93 provided at the other end of the second housing 52 to the one side S1 in the axial direction S, and the rotor core 85 is inserted therethrough.

  Since the fourth bearing 34 is interposed between the held hole 90 and the bearing holding portion 91, the intermediate portion of the rotor core 85 can rotate to the annular extending portion 92 of the second housing 52. It is supported. The rotor core 85 is supported at both ends by the second and fourth bearings 32 and 34 as a pair of bearings arranged with the bearing ring unit 39 sandwiched in the axial direction of the rotor 231.

The permanent magnet 86 of the rotor 231 has different magnetic poles alternately in the circumferential direction C3 of the steering shaft 3, and N poles and S poles are alternately arranged at equal intervals in the circumferential direction C3. The permanent magnet 86 is fixed to the outer peripheral surface of the intermediate portion of the rotor core 85. The positions of the permanent magnet 86 and a part of the transmission ratio variable mechanism 5 in the axial direction S are overlapped with each other.
The stator 232 of the transmission ratio variable mechanism motor 23 is accommodated in an annular first groove 94 formed at the other end of the first housing 51. The first groove 94 is open to the other side S2 in the axial direction S.

The stator 232 includes a stator core 95 formed by laminating a plurality of electromagnetic steel plates and an electromagnetic coil 96.
The stator core 95 includes an annular yoke 97 and a plurality of teeth 98 that are arranged at equal intervals in the circumferential direction of the yoke 97 and project inward in the radial direction of the yoke 97. The outer peripheral surface of the yoke 97 is fixed to the inner peripheral surface of the first groove portion 94 of the first housing 51 by shrink fitting or the like. An electromagnetic coil 96 is wound around each tooth 98.

  A bus bar 99 is arranged on the other side S <b> 2 in the axial direction S with respect to the stator 232. The bus bar 99 is accommodated in the second housing 52 in an annular shape as a whole, and is connected to each electromagnetic coil 96 of the transmission ratio variable mechanism motor 23. The bus bar 99 supplies power from the drive circuit to each electromagnetic coil 96. The positions of the bus bar 99 and the third and fourth bearings 33 and 34 with respect to the axial direction S are overlapped.

A lock mechanism 58 is disposed on the other side S <b> 2 in the axial direction S with respect to the bus bar 99. The lock mechanism 58 is for restricting the rotation of the rotor 231 of the transmission ratio variable mechanism motor 23 and is housed in one end of the second housing 52.
The lock mechanism 58 includes a regulated portion 100 coupled to the rotor core 85 so as to be able to rotate along with the rotor core 85, and a regulating portion 101 for regulating the rotation of the regulated portion 100 by engaging with the regulated portion 100. Yes. The regulated portion 100 is an annular member, and a recess 102 is formed on the outer peripheral surface. The recess 102 is formed at one or a plurality of locations in the circumferential direction of the regulated portion 100. The rotor core 85 may be provided with the recess 102. In this case, the rotor core 85 constitutes the restricted portion. A part of the regulated part 100 is overlapped with a part of the torque sensor 44 in the position in the axial direction S.

The restricting portion 101 is disposed opposite to the restricted portion 100 in the radial direction of the restricted portion 100. The restricting portion 101 is held by the second housing 52 and can be moved to the restricted portion 100 side. When the restricting portion 101 moves toward the restricted portion 100 and engages with the recess 102, the rotation of the rotor core 85 is restricted.
A motor resolver 43 is arranged on the other side S <b> 2 in the axial direction S with respect to the lock mechanism 58. The motor resolver 43 is accommodated in a second groove 103 formed at the other end of the second housing 52, and is located radially outward of the rotor core 85.

The second groove portion 103 is an annular groove defined by an annular outer peripheral portion 104 at one end of the second housing 52 and an annular extending portion 92, and communicates with the first groove portion 94. A housing space 139 for housing the transmission ratio variable mechanism motor 23, the lock mechanism 58, and the motor resolver 43 is defined by the first and second groove portions 94 and 103.
The motor resolver 43 and the torque sensor 44 are opposed to each other in the radial direction R3 of the steering shaft 3. A part of the motor resolver 43 and a part of the torque sensor 44 are overlapped with each other in the axial direction S. The motor resolver 43 includes a resolver rotor 105 and a resolver stator 106. The resolver rotor 105 is fixed to the outer peripheral surface 107 at the other end of the rotor core 85 so as to be able to rotate together. The resolver stator 106 is press-fitted and fixed to the inner peripheral surface 108 of the outer peripheral portion 104 of the second housing 52.

The first bearing 31 supports the input member 20 in a rotatable manner. The first shaft 11 is rotatably supported by the first housing 51 via the cylindrical member 202 of the input member 20 and the first bearing 31. The first bearing 31 is surrounded by the second bearing 32, and both positions are overlapped with respect to the axial direction S.
The third bearing 33 is interposed between the bearing holding hole 110 formed in the inner peripheral portion at the tip of the extending portion 92 of the second housing 52 and the bearing holding portion 111 formed in the output member 22. Yes. The output member 22 is rotatably supported by the annular extending portion 92 of the second housing 52 via the third bearing 33. The third bearing 33 is surrounded by the fourth bearing 34, and both positions are overlapped with each other in the axial direction S.

  Preload is applied between the first convex portions 651 and 652 and the first concave portions 661 and 662 and between the second convex portions 681 and 682 and the second concave portions 691 and 692, respectively. Thereby, the smooth engagement between the first convex portions 651 and 652 and the first concave portions 661 and 662, and the smooth engagement between the second convex portions 681 and 682 and the second concave portions 691 and 692 are achieved. Each is possible.

  Specifically, a screw member 113 is disposed on the inner peripheral portion 112 at one end of the first housing 51. The screw member 113 constitutes a biasing member that biases the input member main body 201 in a biasing direction H (the other side S2 in the axial direction S) that brings the input member main body 201 closer to the output member 22. The screw member 113 constitutes a rigid member that rigidly supports the outer ring 312 of the first bearing 31 in the axial direction S. The screw member 113 urges the input member main body 201 toward the output member 22, so that the first convex portions 651 and 652 and the first concave portions 661 and 662 and the second convex portions 681 and 682 are urged. A preload is applied to each of the second recesses 691 and 692.

  A male screw portion 113 a formed on the outer peripheral surface of the screw member 113 is screwed into a female screw portion 134 a of a bearing holding hole 134 formed on the inner periphery of the annular convex portion 89 at one end of the first housing 51. Thereby, the screw member 113 urges (presses) one end surface of the outer ring 312 of the first bearing 31 held in the bearing holding hole 134 of the first housing 51 in the urging direction H. The outer ring 312 of the first bearing 31 is rotatable with respect to the bearing holding hole 134 and is relatively movable in the axial direction S. A lock nut 135 is provided adjacent to the screw member 113. The lock nut 135 restricts the rotation of the screw member 113 in a state where the lock nut 135 is screwed into the female screw portion 134a.

The inner ring 311 of the first bearing 31 is connected to the one end of the cylindrical member 202 so as to be able to rotate together with the end of the cylindrical member 202, and can be rotated together with the input member main body 201 via the cylindrical member 202. In addition, it is possible to move in the axial direction S. The inner ring 311 is in contact with one end portion of the input member main body 201 and presses the input member main body 201 in the urging direction H.
The first convex portions 651 and 652 are opposed to the first concave portions 661 and 662 in the urging direction H. Similarly, the second concave portions 691 and 692 are opposed to the second convex portions 681 and 682 in the urging direction H. An inner ring 331 of a third bearing 33 is press-fitted and fixed to the output member 22. The output member 22 has a central stepped portion in contact with one end surface of the inner ring 331 and presses the inner ring 331 in the urging direction H. The outer ring 332 of the third bearing 33 is received by an annular step 114 disposed adjacent to the bearing holding hole 110 that holds the outer ring 332 so as to be movable in the biasing direction H, and moves in the biasing direction H. Is regulated. The movement of the output member 22 in the biasing direction H is regulated by the third bearing 33.

  With the above configuration, the urging force of the screw member 113 is transmitted to the inner ring 311 via the outer ring 312 and the rolling element of the first bearing 31 and further transmitted to the input member main body 201. The urging force transmitted to the input member main body 201 is transmitted in the order of the first convex portions 651 and 652 and the first concave portions 661 and 662, and the second concave portions 691 and 692 and the second convex portions 681 and 682, Further, it is transmitted to the inner ring 331, the rolling elements and the outer ring 332 of the third bearing 33. The urging force transmitted to the outer ring 332 of the third bearing 33 is received by the annular step portion 114.

As the inner ring 391 of the raceway ring unit 39 moves in the biasing direction H by the biasing force of the screw member 113, the rolling elements 393, the outer ring 392 of the raceway ring unit 39 and the rotor 231 of the transmission ratio variable mechanism motor 23 are It moves together in the urging direction H.
Specifically, the outer ring 392 of the track ring unit 39 is press-fitted and fixed in the inclined hole 63 of the rotor core 85. Thus, the rotor core 85 holds the outer ring 392 so as to be able to rotate along the first axis A and move along the axial direction S.

  Further, the outer rings 322 and 342 of the second bearing 32 and the fourth bearing 34 are loosely fitted in the corresponding annular held holes 87 and 90 of the rotor core 85, respectively, so that the rotor core 85 is relative to the axial direction S. Supports movable. The inner ring 321 of the second bearing 32 is press-fitted and fixed to the bearing holding portion 88 of the annular convex portion 89. The inner ring 341 of the fourth bearing 34 is press-fitted and fixed to the bearing holding portion 91 of the annular extending portion 92 of the second housing 52.

  Note that the screw member 113 may be used to bias the output member 22 in a biasing direction (a direction opposite to the biasing direction H) approaching the input member main body 201. In this case, the screw member 113 is screwed into the bearing holding hole 110 that holds the third bearing 33. The urging force of the screw member 113 includes the third bearing 33, the output member 22, the second convex portions 681, 682 and the second concave portions 691, 692, the first concave portions 661, 662 and the first convex portion 651. 652, the input member main body 201, the inner ring 311 of the first bearing 31, the rolling elements, and the outer ring 312 are transmitted in this order and received by the first housing 51.

  Further, the movement of the inner ring 391 in the urging direction H is prevented from being hindered by the support mechanism 133. Specifically, the outer ring 382 of the eighth bearing 38 of the support mechanism 133 is loosely fitted in the bearing holding hole 109 of the cylindrical member 202 and can be moved relative to the bearing holding hole 109 in the axial direction S. Has been. The inner ring 381 of the eighth bearing 38 is press-fitted and fixed to the opposed end portion 12 a of the second shaft 12. Alternatively, the outer ring 382 of the eighth bearing 38 may be press-fitted and fixed in the bearing holding hole 109, and the inner ring 381 may be loosely fitted to the facing end 12a.

The torque sensor 44 is disposed radially inward of the rotor core 85 of the transmission ratio variable mechanism motor 23, and includes a multipolar magnet 115 fixed to the intermediate portion of the second shaft 12, and the third shaft 13. It includes a pair of magnetic yokes 116 and 117 as soft magnetic bodies that are supported at one end and are arranged in a magnetic field generated by the multipolar magnet 115 to form a magnetic circuit.
The multipolar magnet 115 is a cylindrical permanent magnet, and a plurality of poles (the same number of N and S respectively) are magnetized at equal intervals in the circumferential direction.

The magnetic yokes 116 and 117 are opposed to the multipolar magnet 115 with a predetermined gap in the radial direction of the multipolar magnet 115, and surround the multipolar magnet 115. 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 a pair of magnetism collecting rings 119 and 120 that guide magnetic flux from the magnetic yokes 116 and 117. The pair of magnetism collecting rings 119 and 120 are annular members formed using a soft magnetic material, surround the magnetic yokes 116 and 117, and are magnetically coupled to the magnetic yokes 116 and 117, respectively. .

The pair of magnetism collecting rings 119 and 120 are separated from each other in the axial direction S and face each other. The magnetism collecting rings 119 and 120 are molded by the synthetic resin member 121. The synthetic resin member 121 is held by the annular extending portion 92 of the second housing 52.
Magnetic flux is generated in the magnetic yokes 116 and 117 in accordance with the relative rotational 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, and the synthetic resin member 121. It is detected by a Hall IC (not shown) embedded in. Thereby, the magnetic flux density according to the torque applied to the second shaft 12 (steering member) can be detected.

  Referring to FIG. 2, 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 is interposed between a bearing holding portion 122 formed on the outer periphery of one end of the third shaft 13 and a bearing holding hole 123 formed in the partition wall portion 93 of the second housing 52. Yes. The bearing holding hole 123 rotatably supports one end of the third shaft 13 through the fifth bearing 35.

  The third shaft 13 surrounds the second shaft 12 and the torsion bar 14. Specifically, an insertion hole 124 opened at one end of the third shaft 13 is formed in the third shaft 13. The other end of the second shaft 12 is inserted through the insertion hole 124. An insertion hole 125 extending in the axial direction S is formed in the second shaft 12, and the torsion bar 14 is inserted through the insertion hole 125.

  One end of the torsion bar 14 is connected to one end of the insertion hole 125 of the second shaft 12 so as to be able to rotate together by serration fitting or the like. The other end of the torsion bar 14 is connected to the insertion hole 124 of the third shaft 13 by serration fitting or the like so as to be able to rotate together. A radially inner space of the annular extending portion 92 of the second housing 52 is a torque sensor housing chamber 126, and a structure for suppressing the intrusion of the lubricant into the torque sensor housing chamber 126 is further provided. It has been.

  Specifically, a third bearing 33 with a seal disposed at one end of the annular extending portion 92 of the second housing 52, an output member 22 disposed radially inward of the third bearing 33, One end of the torque sensor housing chamber 126 is closed by the second shaft 12 disposed radially inward of the output member 22. Further, torque is generated by the fifth bearing 35 with seal, the third shaft 13 disposed radially inward of the fifth bearing 35, and the torsion bar 14 that closes the insertion hole 124 of the third shaft 13. The other end of the sensor chamber 126 is closed.

With the above configuration, the lubricant filled in the first recesses 661, 662, the second recesses 691, 692 and the grooves 301, 302 can be prevented from entering the torque sensor housing chamber 126, and It is possible to suppress the lubricant filled in the meshing region of the worm shaft 27 and the worm wheel 28 of the speed reduction mechanism 26 from entering the torque sensor housing chamber 126.
The 2nd shaft 12 and the 3rd shaft 13 are mutually supported through the 6th bearing 36 so that relative rotation is possible. The sixth bearing 36 is surrounded by the worm wheel 28 of the speed reduction mechanism 26. The speed reduction mechanism 26 is accommodated in an accommodation chamber 128 defined by the outer peripheral portion 127 and the end wall portion 61 of the third housing 53 and the partition wall portion 93 of the second housing 52. A part of the worm wheel 28 and the sixth bearing 36 overlap with each other in the position in the axial direction S.

A seventh bearing 37 is interposed between the intermediate portion of the third shaft 13 and the end wall portion 61 of the third housing 53. The end wall portion 61 supports the third shaft 13 via the seventh bearing 37 so as to be rotatable.
The inner ring 371 of the seventh bearing 37 is sandwiched between an annular step 129 formed on the outer peripheral portion of the third shaft 13 and a nut member 130 screwed to the outer peripheral portion of the third shaft 13. Yes. The outer ring 372 of the seventh bearing 37 is sandwiched between an annular step 131 formed in the third housing 53 and a retaining ring 132 held by the third housing 53.

  Next, an example of the operation of the vehicle steering apparatus 1 will be described. In the following, (i) the rotation of the rotor 231 of the transmission ratio variable mechanism motor 23 is restricted, and (ii) the rotor 231 of the transmission ratio variable mechanism motor 23 is rotating, and the input member. The case where the rotation of the motor 20 is restricted and the case where (iii) the rotor 231 of the transmission ratio variable mechanism motor 23 is rotating and the input member 20 is rotating will be described.

In any of the cases (i), (ii), and (iii), the total number of the first convex portions 651 and 652 is 38, the total number of the first concave portions 661 and 662 is 40, and the second In the following description, it is assumed that the total number of the convex portions 681 and 682 is 40 and the total number of the second concave portions 691 and 692 is 40.
In the case of the above (i), that is, when the rotation of the rotor 231 of the transmission ratio variable mechanism motor 23 is restricted by the lock mechanism 58, when the first shaft 11 is rotated by the operation of the steering member, the input member body 201 The first convex portions 651 and 652 rotate around the first axis A. At this time, the bearing ring unit 39 does not perform the Coriolis motion that rotates around the first axis A, and only the inner ring 391 rotates around the second axis B. By this rotation, the inner ring 391 provided with the first recesses 661 and 662 is rotated, and the second shaft 12 is further rotated.

As a result, the inner ring 391 rotates 38/40 when the input member 20 rotates once. At this time, the output member 22 rotates 38/40. That is, the rotation of the input member 20 is decelerated to 19/20.
In the case of (ii) above, that is, when the rotor 231 of the transmission ratio variable mechanism motor 23 is rotating and the rotation of the input member 20 is restricted by the driver holding the steering member, As the rotor 231 rotates around the first axis A, the race ring unit 39 performs Coriolis motion. As a result, the inner ring 391 attempts to rotate the input member 20 and the output member 22 in the opposite directions. However, because the rotation of the input member 20 is restricted, only the output member 22 rotates.

  At this time, when the total number of the first concave portions 661 and 662 is increased by two compared to the total number of the first convex portions 651 and 652, the outer ring 392 of the raceway ring unit 39 is rotated once. In addition, the phase of the inner ring 391 advances by an amount corresponding to the difference in the number of teeth (two). This is the rotation of the inner ring 391. As a result, when the outer ring 392 rotates once, the inner ring 391 rotates by an amount corresponding to the difference in the number of teeth, and the output member 22 rotates 2/40. As described above, the rotation of the rotor 231 of the transmission ratio variable mechanism motor 23 is reduced to 1/20 and output.

In the case of (iii) above, that is, when the input member 20 is rotated by rotating the rotor 231 of the transmission ratio variable mechanism motor 23 and steering the steering member by the driver, The rotation amount of the output member 22 is a value obtained by adding the rotation amount of the input member 20 (steering member) to the rotation amount of (ii) above.
As a result, when the vehicle is traveling at a relatively low speed or the like, the transmission ratio (θ2 / θ1) can be increased to reduce the amount of operation of the steering member 2 by the driver, and the vehicle can be steered.

  When the vehicle is traveling at a relatively high speed, for example, the behavior of the vehicle is determined by comparing the steering angle θ1 with the yaw rate γ of the vehicle. As a result, when the vehicle behavior determined from the steering angle θ1 does not match the vehicle behavior determined from the detected yaw rate γ, the rotation of the rotor 231 of the transmission ratio variable mechanism motor 23 is increased. The vehicle's stability control (posture stability control) is performed by decelerating or decelerating. At this time, the drive of the rotor 231 of the transmission ratio variable mechanism motor 23 can be controlled so that the counter steering operation is performed.

  According to the present embodiment, during straight traveling, the hardness of the first convex portion 651 and the first concave portion 661 of the first regions P1 and Q1 that are fitted to each other between the input member 20 and the inner ring 391 is relatively set. Therefore, the occurrence of fretting wear on the input member 20 and the first power transmission surfaces 70 and 71 of the inner ring 391 can be suppressed. In addition, the hardness of the second convex portions 681 and the second concave portions 691 of the first regions U1 and W1 that are fitted to each other between the output member 22 and the inner ring 391 during straight traveling is relatively high. Therefore, occurrence of fretting wear on the output member 22 and the second power transmission surfaces 72 and 73 of the inner ring 391 can be suppressed.

  Moreover, the difference in hardness is easily achieved by changing the material. That is, the material of the first convex portion 651 as the fitable portion of the first region P1 is different from the material of the first convex portion 652 as the fitable portion of the second region P2, and By differentiating the material of the second convex portion 681 as the fitting portion of the first region U1 and the material of the second convex portion 682 as the fitting portion of the second region U2, A hardness difference can be easily achieved.

  Further, by forming the inner ring 391 with the inner ring main body 391A and the high hardness members 391B and 391C, the material of the first recess 661 as the fitting portion of the first region Q1 and the fitting of the second region Q2 The material of the first recessed portion 662 as the possible portion is made different, and the material of the second recessed portion 691 as the fitable portion of the first region W1 and the fitable portion of the second region W2 The second recess 692 is made of a different material, so that a hardness difference is easily achieved.

In particular, since the first convex portions 651 and 652 and the second convex portions 681 and 682 are configured using the roller members 311, 312; 321, 322, the setting of the hardness difference is remarkably easy.
Moreover, when the 1st convex part 651 and the 1st recessed part 661 as a fitting possible part of 1st area | region P1, Q1 are comprised with ceramics, the fitting possible part of 1st area | region U1, W1 When the second convex portion 681 and the second concave portion 691 are made of ceramics, fretting wear can be remarkably reduced.

  FIG. 12 shows another embodiment of the present invention. Referring to FIG. 12, this embodiment is different from the embodiment of FIG. 7 as follows. That is, the first protrusions 6510 and 6520 are formed integrally with the input member main body 201 of the input member 20 from a single material. Further, the surface of the first convex portion 6510 in the first region P1 is formed by the high hardness layer 700 having a higher hardness than the surface of the first convex portion 6520 in the second region P2. The high hardness layer 700 may be, for example, a ceramic coating layer or a carbonitriding layer. Examples of ceramics include silicon nitride, silicon carbide, zirconia, and alumina. Although not shown, the same configuration as that of the first convex portion 6510 may be applied to the second convex portion 681.

  Further, the high hardness member 391B is eliminated, and the surface of the first recess 6610 in the first region Q1 is formed by the high hardness layer 701 having a higher hardness than the surface of the first recess 662 in the second region Q2. Has been. The high hardness layer 701 may be, for example, a ceramic coating layer or a carbonitriding layer. Examples of ceramics include silicon nitride, silicon carbide, zirconia, and alumina. Although not shown, the same configuration as that of the first recess 6610 may be applied to the second recess 691.

In this embodiment, in addition to reducing the fretting wear, the number of parts of the transmission ratio variable mechanism 5 can be reduced in addition to reducing the fretting wear. There is an advantage that can be made easier. Further, as a secondary effect, the steering rigidity during straight traveling is improved, so that there is an advantage that straight running stability is improved.
In each of the above-described embodiments, the fretting wear of the convex portion and the concave portion as the fitable portion of the first region is prevented by changing the material of the first region. By increasing the fitting force between the matable parts in the first region to be larger than the fitting force between the matable parts in the second region, the coupling rigidity between the matable parts in the first region is increased. Thus, the effect of preventing fretting wear may be further enhanced.

For example, as shown in FIG. 13, the fitting force between the first convex portion 651A and the first concave portion 661 as the fitting possible portion of the first regions P1, Q1 of the first power transmission surfaces 70, 71 is as follows. The fitting force between the first convex portion 652 and the first concave portion 662 as the fitting possible portion of the second regions P2 and Q2 is made larger.
Specifically, in the power transmission surface 70, for example, the diameter R1 of one end of the roller member 311A constituting the first convex portion 651A of the first region P1 constitutes the first convex portion 652 of the second region. Since the diameter R2 of the same side end of the roller member 312 is made larger (R1> R2), the fitting between the first convex portion 651A and the first concave portion 661 in the first regions P1, Q1 is achieved. The fitting is stronger than the fitting between the first convex portion 652 and the first concave portion 662 in the second regions P2 and Q2. The difference between the diameter R1 and the diameter R2 is preferably about 10 μm to 30 μm.

  Conversely, as shown in FIG. 14, in the power transmission surface 71, the diameter R5 of the first recess 661A in the first region Q1 is larger than the diameter R6 of the diameter R6 of the first recess 662 in the second region Q2. (R5 <R6), the fitting between the first convex portion 651 and the first concave portion 661A in the first region P1, Q1 is the first region in the second region P2, Q2. The fitting may be stronger than the fitting between the convex portion 652 and the first concave portion 662. The difference between the diameter R5 and the diameter R6 is preferably about 10 μm to 30 μm.

Further, as shown in FIG. 15, a configuration (R1> R2) in which the diameter R1 of the roller member 331A constituting the first convex portion 651A of the first region P1 shown in FIG. 14 may be employed in combination with the configuration (R5 <R6) in which the diameter R5 of the first recess 661A in the first region Q1 shown in FIG. 14 is relatively small.
Further, by adopting the same configuration as any one of FIGS. 13 to 15, the fitting force between the fitting portions of the first regions U1 and W1 of the second power transmission surfaces 72 and 73 is set to the second region U2. , W2 may be larger than the fitting force between the fitting possible parts, and the effect of preventing fretting wear may be enhanced.

  When any one of the configurations shown in FIGS. 13 to 15 is adopted, when the steering member 2 is rotated, the steering angle θ1 is a region within a predetermined range including the steering center (for example, FIG. 13). In this case, the detected steering torque T is temporarily increased during the passage of the first convex portion 651A and the first concave portion 661 of the first regions P1 and Q1). After passing through the range, the detected steering torque T decreases. For this reason, when steering assist control is performed on the steering assist motor 25 based on the steering torque T, the assist force during the passage is large and the assist force after the passage is small. There is a risk of discomfort.

  Therefore, it is preferable to implement the following control regarding the steering assist control. That is, referring to FIG. 16, the detection values of each sensor (specifically, the steering angle θ1, the vehicle speed V, and the steering torque T) are input (step S1), and the map stored in advance (the steering torque T and the steering assist). The output of the steering assist motor 25 is set based on a map storing the relationship with the output of the motor 25 for each vehicle speed V (step S2).

  If the detected steering angle θ1 is within a predetermined range including the steering center (−θa <θ1 <θa) when the steering member 2 is being rotated (if YES in step S3), The output of the steering assist motor 25 is corrected so as to once decrease with respect to the detected steering torque T (step S4). On the other hand, when the detected steering angle θ1 is not within the predetermined range including the steering center (−θa <θ1 <θa) (NO in step S3), the output of the steering assist motor 25 is output in step S2. Set as the output set in (normal output).

The steering assist motor 25 is subjected to steering assist control so that the output set in this way is obtained (step S5).
As a result, the change in the steering reaction force of the steering member 2 can be reduced between when the steering angle θ1 is passing through the predetermined range and before or after the passage. Can be improved.

  The present invention is not limited to the above-described embodiment. For example, the first power transmission surface 70 is provided with a first recess as a fitting portion and can be fitted to the first power transmission surface 71. The 1st convex part as a part may be provided. Similarly, even if the second power transmission surface 72 is provided with a second concave portion as a fitable portion and the second power transmission surface 73 is provided with a second convex portion as a fitable portion. Good.

Further, the input member main body 201 and the cylindrical member 202 may be integrally formed of a single material to constitute the input member. In the above embodiment, the intermediate member is the inner ring itself, but the intermediate member may be a member that rotates along with the inner ring.
In the above embodiment, the intermediate member is an inner ring or a member that rotates together with the inner ring. Alternatively, the intermediate member may be an outer ring or a member that rotates together with the outer ring. In this case, the transmission ratio variable mechanism motor 23 drives the inner ring.

It is a mimetic diagram showing a schematic structure of a steering device for vehicles concerning one embodiment of the present invention. It is sectional drawing which shows the more concrete structure of the principal part of FIG. FIG. 3 is an enlarged view of a transmission ratio variable mechanism in FIG. 2 and its surroundings. It is the side view which represented a part of transmission ratio variable mechanism with the cross section. It is a disassembled perspective view of the principal part of an input member and an inner ring. It is the schematic of the 1st power transmission surface of an input member. It is the schematic of the 1st power transmission surface of an inner ring. It is a schematic side view which shows mesh | engagement with the 1st convex part and 1st recessed part of the 1st area | region of a 1st power transmission surface. It is sectional drawing of the 1st convex part and 1st recessed part which mutually mesh | engage. It is a disassembled perspective view of the principal part of an output member and an inner ring. It is the schematic of the 2nd power transmission surface of an output member. It is the schematic of the 2nd power transmission surface of an inner ring. It is a schematic side view which shows mesh | engagement with the 1st convex part and 1st recessed part of the 1st area | region of a 2nd power transmission surface. In another embodiment of this invention, it is a schematic side view which shows mesh | engagement with the 1st convex part and 1st recessed part of the 1st area | region of a 1st power transmission surface. In another embodiment of this invention, it is a disassembled perspective view of the principal part of an input member and an inner ring | wheel. In another embodiment of this invention, it is a disassembled perspective view of the principal part of an input member and an inner ring | wheel. In another embodiment of this invention, it is a disassembled perspective view of the principal part of an input member and an inner ring | wheel. 16 is a flowchart showing an example of steering assist control combined with any of the embodiments of FIGS.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Steering device for vehicles, 2 ... Steering member, 4L, 4R ... Steering wheel, 5 ... Transmission ratio variable mechanism, 10 ... Steering mechanism, 11 ... 1st shaft (1st axis), 12 ... 2nd Shaft (second shaft), 19 ... steering assist force applying mechanism, 20 ... input member, 22 ... output member, 23 ... transmission ratio variable mechanism motor, 25 ... steering assist motor, 651, 6510, 651A ... (first) (First region) first convex portion (fitable portion), 652, 6520 (first region) first convex portion (fitable portion), 661, 6610, 661A (first region) First recess (of the area), 662... (Second area) of the first recess (fit area), 681... (Second area) of the second protrusion (fit) ,... 682 (second region) second convex portion (fitable portion), 691... (First region) second concave portion (fitable portion) 692 (second region) second recess (fitable portion), 70 (input member) first power transmission surface, 71 (intermediate member) first power transmission surface, 72 ... second power transmission surface (of output member), 73 ... second power transmission surface of (intermediate member), 133 ... support mechanism, 201 ... input member body, 202 ... cylindrical member, 301,302 ... groove, 311 ... 311A ... (forms first convex part of first region) roller member, 312 ... (forms first convex part of second region) roller member, 321 ... (of first region) Roller member forming the second convex portion, 322... (Forming the second convex portion of the second region) roller member, 391... Inner ring, 391A... Inner ring main body, 391B and 391C. ... outer ring, 393 ... rolling element, 700, 701 ... high hardness layer, 800 ... grease reservoir, A ... first Axis, B ... second axis, θ1 ... steering angle, θ2 ... steering angle, θ2 / θ1 ... transmission ratio, R1 ... (forms the first convex part in the first region) diameter of roller member, R2 ... the diameter of the roller member (forming the first convex part of the second region), R5 ... (the first concave part of the first region), R6 ... (the first concave part of the second region) ) Diameter, T ... Steering torque, V ... Vehicle speed

Claims (6)

A transmission ratio variable mechanism capable of changing the transmission ratio, which is the ratio of the steering angle of the wheel to the steering angle of the steering member,
The transmission ratio variable mechanism includes an input member coupled to the steering member and rotatable about a first axis, an output member coupled to a wheel and rotatable about the first axis, and an input member and an output member. An intermediate member that is interposed between the two members so as to allow differential rotation of the two members,
The intermediate member is rotatable about a second axis inclined with respect to the first axis;
The input member and the intermediate member each include an annular first power transmission surface having a fitting portion that can be fitted to each other,
The output member and the intermediate member each include an annular second power transmission surface having a fitting portion that can be fitted to each other,
Each of the first power transmission surface and the second power transmission surface includes a first region that fits when the steering angle is within a predetermined angle range including the steering center, and the steering angle is the predetermined angle. A second region that fits together when out of range,
The vehicular steering apparatus, wherein the fittable portion in the first region is harder than the fittable portion in the second region.   The vehicle steering apparatus according to claim 1, wherein a material of the fitting portion in the first region and a material of the fitting portion in the second region are different from each other.   3. The vehicle steering apparatus according to claim 2, wherein the fitting portion of the first region includes ceramics.   4. The vehicle according to claim 1, wherein the fitting force of the fitting portion of the first region is larger than the fitting force of the fitting portion of the second region. Steering device. In Claim 4, the at least one fitting portion of the first power transmission surface and the second power transmission surface includes a convex portion and a concave portion that are fitted to each other,
The first region so that the fitting of the convex portion of the first region and the concave portion of the first region is a stronger fitting than the fitting of the convex portion of the second region and the concave portion of the second region. The vehicle is characterized in that the convex portion of the first region is made larger than the convex portion of the second region, or the concave portion of the first region is made smaller than the concave portion of the second region. Steering device. In Claim 5, the above-mentioned convex part is formed with a roller member,
A vehicle steering apparatus, wherein a diameter of a roller member forming a convex portion in the first region is made larger than a diameter of a roller member forming a convex portion in the second region.

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