Steering device

Abstract

The steering device (1) includes: a pinion (31) having helical teeth; and a rack (40) having rack teeth (41) having a plurality of helical teeth meshing with the pinion (31). The rack teeth (41) have: a wide-pitch portion (46) having a plurality of rack teeth (41) arranged at a predetermined pitch; and a narrow-pitch portion (45) having a pitch of a plurality of rack teeth (41) narrower than the pitch of the rack teeth (41) located in the wide-pitch portion (46) relative to each other. The rack teeth (41) located in the wide-pitch portion (46) have a fixed tooth thickness in the tooth width direction (W). The rack teeth (41) located in the narrow-pitch portion (45) have a tooth thickness variation portion (42) on one side of the tooth thickness direction (T). The tooth thickness of the end of the tooth thickness variation portion (42) in the tooth width direction (W) is smaller than the tooth thickness of the center in the tooth width direction (W). This allows the change in steering resistance during steering to be suppressed without reducing the rigidity of the rack (40).

Description

Technical Field

[0001] This disclosure relates to steering mechanisms. Background Technology

[0002] The steering mechanism includes a pinion that rotates due to the rotational torque generated when the steering wheel is turned, and a rack with rack teeth that mesh with the pinion. This configuration transmits the rotational torque input from the steering wheel to the rack, causing it to move linearly, thereby changing the orientation of the steering wheels according to the steering angle of the steering wheel. Furthermore, conventional steering mechanisms include a so-called variable gear ratio mechanism that varies the spacing of the rack teeth along the long side of the rack depending on their position.

[0003] For example, in the steering device described in Patent Document 1, the meshing portion of the rack shaft, composed of multiple rack teeth, has a narrow-pitch portion and a wide-pitch portion with different tooth spacings. Furthermore, in the steering device described in Patent Document 1, which has the narrow-pitch and wide-pitch portions as described above, a rack bushing that supports the rack shaft is provided. By making the sliding resistance between the rack shaft and the rack bushing when the pinion teeth mesh with the narrow-pitch portion less than the sliding resistance when the pinion teeth mesh with the wide-pitch portion, variations in steering reaction force caused by the steering angle are suppressed.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2017-136905 Summary of the Invention

[0007] The problem that the invention aims to solve

[0008] Here, in Patent Document 1, the diameter of the rack shaft is changed to alter the sliding resistance between the rack shaft and the rack bushing. Specifically, the portion of the rack shaft that slides against the rack bushing when the pinion teeth mesh with the narrow-pitch portion is designated as the small-diameter portion, and the portion that slides against the rack bushing when the pinion teeth mesh with the wide-pitch portion is designated as the large-diameter portion. Therefore, when the pinion teeth mesh with the narrow-pitch portion, the sliding resistance is reduced because the small-diameter portion slides against the rack bushing, compared to the case where the large-diameter portion slides against the rack bushing when the pinion teeth mesh with the wide-pitch portion.

[0009] However, reducing the diameter of the rack reduces its support rigidity, thus decreasing its rigidity during steering and potentially reducing steering feel. Therefore, in steering systems with racks having a spacing of multiple rack teeth, there is room for improvement in ensuring rack rigidity while suppressing variations in steering resistance, such as sliding resistance that varies with the spacing.

[0010] This disclosure was made in view of the above circumstances, and its object is to provide a steering device that can suppress changes in steering resistance during steering without reducing the rigidity of the rack.

[0011] Methods for solving problems

[0012] The steering device disclosed herein includes: a pinion gear having helical teeth; and a rack having a plurality of helical teeth meshing with the pinion gear, the rack having: a wide-pitch portion having a plurality of rack teeth arranged at a predetermined spacing; and a narrow-pitch portion having a spacing between the plurality of rack teeth narrower than the spacing between the rack teeth located in the wide-pitch portion, the rack teeth located in the wide-pitch portion having a fixed tooth thickness in the tooth width direction, and the rack teeth located in the narrow-pitch portion having a tooth thickness variation portion on one side of the tooth thickness direction, the tooth thickness at the end of the tooth thickness variation portion in the tooth width direction being smaller than the tooth thickness at the center in the tooth width direction.

[0013] According to this structure, since the rack teeth located in the narrow-pitch section have a tooth thickness variation portion 42, when the rotating pinion contacts the rack teeth located in the narrow-pitch section, it is difficult for them to contact near the end of the rack teeth in the tooth width direction. Therefore, the ease of contact between the rack teeth located in the narrow-pitch section and the pinion due to the narrow pitch, as well as the difficulty of contact between the rack teeth and the pinion near the end of the rack teeth in the tooth width direction, can be offset. Therefore, the difference between the maximum and minimum number of rack teeth that simultaneously contact the pinion can be reduced. By locally reducing the diameter of the rack rod, the variation in steering resistance during steering can be reduced without changing the sliding resistance between the rack rod and the rack bushing. As a result, the variation in steering resistance during steering can be suppressed without reducing the rigidity of the rack rod.

[0014] The steering device disclosed herein includes: a pinion gear having helical teeth; and a rack having a plurality of helical teeth meshing with the pinion gear, the rack having: a wide-pitch portion having a plurality of rack teeth arranged at a predetermined spacing; and a narrow-pitch portion having a spacing between the plurality of rack teeth narrower than the spacing between the rack teeth located in the wide-pitch portion, wherein the rack teeth located in the wide-pitch portion have a tooth thickness variation portion on one side of the tooth thickness direction, the tooth thickness at the end of the tooth thickness variation portion in the tooth width direction being smaller than the tooth thickness at the center in the tooth width direction, and the rack teeth located in the narrow-pitch portion have the tooth thickness variation portion on both sides of the tooth thickness direction.

[0015] According to this structure, by forming a tooth thickness variation section on one side of the rack teeth located in the wide-pitch section and forming tooth thickness variation sections on both sides of the rack teeth located in the narrow-pitch section, the difference between the maximum and minimum number of teeth of the rack teeth simultaneously in contact with the pinion can be reduced. Therefore, by locally reducing the diameter of the rack rod, the variation in steering resistance during steering can be reduced without changing the sliding resistance between the rack rod and the rack bushing. As a result, the variation in steering resistance during steering can be suppressed without reducing the rigidity of the rack rod 40.

[0016] As a preferred embodiment, the tooth thickness variation section is a protrusion with the largest tooth thickness at the center in the tooth width direction and the tooth thickness decreasing towards the end in the tooth width direction.

[0017] According to this structure, since the tooth thickness variation section is a protrusion, when the rotating pinion contacts the rack teeth located in the narrow-pitch section, it is difficult for them to make contact near the end in the tooth width direction. This compensates for both the ease of contact between the rack teeth in the narrow-pitch section and the difficulty of contact near the end in the tooth width direction due to the protrusion. Therefore, the difference between the maximum and minimum number of rack teeth simultaneously contacting the pinion can be reduced, thus reducing variations in steering resistance during steering. As a result, variations in steering resistance during steering can be suppressed without reducing the rigidity of the rack.

[0018] As a preferred embodiment, the narrow-pitch portion is disposed at the center and both ends of the range in the long side direction of the rack bar where a plurality of rack teeth are disposed, and the wide-pitch portion is disposed between the narrow-pitch portions in the center and both ends of the long side direction of the rack bar.

[0019] According to this structure, the narrow-pitch portions are positioned at the center and both ends of the area where the rack teeth are located. Therefore, the narrow-pitch portion at the center ensures a good steering feel near straight-line driving, while the narrow-pitch portions at both ends reduce stress on the rack teeth near the maximum steering angle, thus ensuring durability. Furthermore, since the wide-pitch portions are positioned between the center and both narrow-pitch portions along the long side of the rack, the wide-pitch portions improve the responsiveness of the steering angle relative to steering between straight-line driving and the maximum steering angle, ensuring a good steering feel when steering at a larger steering angle than during straight-line driving. As a result, both the steering feel during vehicle operation and the durability of the rack can be improved simultaneously.

[0020] As a preferred embodiment, the narrow-pitch portion is disposed at the center of the area in the long side direction of the rack bar where a plurality of rack teeth are disposed, and the wide-pitch portion is disposed on both sides of the narrow-pitch portion in the long side direction of the rack bar.

[0021] According to this structure, the narrow-pitch section is positioned in the center of the area where the rack teeth are located, and wide-pitch sections are formed at both ends of the narrow-pitch section, thus improving responsiveness when steering at a larger steering angle. As a result, steering feel is improved.

[0022] As a preferred embodiment, the number of rack teeth that simultaneously contact the pinion is between two and four.

[0023] According to this structure, the number of rack teeth in simultaneous contact with the pinion is two or more, thus suppressing impact noise and improving steering feel. Furthermore, since the number of rack teeth in simultaneous contact with the pinion is four or fewer, the difference between the maximum and minimum number of rack teeth in simultaneous contact with the pinion can be reduced, thereby minimizing fluctuations in steering resistance during steering. As a result, fluctuations in steering resistance during steering can be suppressed, impact noise can be reduced, and steering feel can be improved.

[0024] Invention Effects

[0025] The steering device disclosed herein has the following effect: it can suppress changes in steering resistance during steering without reducing the rigidity of the rack. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the steering device in the embodiment.

[0027] Figure 2 yes Figure 1 The front view of the rack rod shown.

[0028] Figure 3 It is configured in Figure 2 A detailed view of the rack teeth in the wide-spacing section is shown.

[0029] Figure 4 It is configured in Figure 2 A detailed view of the rack teeth in the narrow-pitch section shown.

[0030] Figure 5 This is an explanatory diagram showing the change in the number of rack teeth that are simultaneously in contact with the pinion when a rack without a protruding rack bar comes into contact with a rotating pinion.

[0031] Figure 6 This is an explanatory diagram showing the change in the number of rack teeth that are simultaneously in contact with a rotating pinion when the rack teeth, which have protrusions on both sides of the rack teeth, come into contact with the pinion.

[0032] Figure 7 This is an explanatory diagram showing the change in the number of rack teeth that are simultaneously in contact with a rotating pinion when a rack tooth with a protrusion on one side of a rack tooth located in a narrow-pitch section comes into contact with the pinion.

[0033] Figure 8 This is an explanatory diagram showing the gear contact state between the two rack teeth and the pinion.

[0034] Figure 9 This is a variation of the steering device in the embodiment, and is a schematic diagram showing a narrow-pitch portion disposed in the center of the rack tooth configuration range.

[0035] Figure 10 This is a variation of the steering device according to the embodiment, and is an explanatory diagram showing a method in which a tooth thickness variation portion is formed on one side of the rack teeth arranged in the wide-spacing portion.

[0036] Figure 11 This is a variation of the steering device according to the embodiment, and is an explanatory diagram showing a method in which a tooth thickness variation portion is formed on both sides of the rack teeth arranged in the narrow pitch portion. Detailed Implementation

[0037] The present disclosure will now be described in detail with reference to the accompanying drawings. Furthermore, the present disclosure is not limited to methods for carrying out the invention described below (hereinafter referred to as embodiments). Additionally, the constituent elements in the following embodiments include elements readily conceived by those skilled in the art, substantially the same elements, and elements of so-called equivalent scope. Moreover, the constituent elements disclosed in the following embodiments can be appropriately combined.

[0038] [Implementation Method]

[0039] Figure 1This is a schematic diagram of the steering device 1 according to the embodiment. In the accompanying drawings, D1 represents the upper side (one side of the axial direction) and D2 represents the lower side (the other side of the axial direction). In addition, in the description of the embodiment, the upper side (one side of the axial direction) is sometimes referred to as the D1 side and the lower side (the other side of the axial direction) is referred to as the D2 side.

[0040] like Figure 1 As shown, the steering device 1 includes a steering wheel 20, a first steering shaft 21, a second steering shaft 22, a pinion shaft 30, a rack rod 40, a worm gear reducer 50, a tie rod 60, a rack housing 10, an ECU 80, and a power supply device 85.

[0041] The first steering shaft 21 is connected to the steering wheel 20. The first steering shaft 21 is supported to be rotatable. The first steering shaft 21 rotates by the torque that turns the steering wheel 20. Specifically, when the driver holds the steering wheel 20 and turns it, its rotational torque (steering torque) is transmitted to the first steering shaft 21, and the first steering shaft 21 rotates.

[0042] The second steering shaft 22 is connected to the first steering shaft 21 via the first universal joint 26. The second steering shaft 22 is supported to be rotatable. The rotational torque of the first steering shaft 21 is transmitted to the second steering shaft 22 via the first universal joint 26, and the second steering shaft 22 rotates.

[0043] The rack housing 10 is formed in a cylindrical shape. In addition, a pinion housing 11 and a reducer housing 12 are provided in the rack housing 10.

[0044] like Figure 1 As shown, the pinion shaft 30 is connected to the second steering shaft 22 via the second universal joint 27. The rotational torque of the second steering shaft 22 is transmitted to the pinion shaft 30 via the second universal joint 27, causing the pinion shaft 30 to rotate. A pinion 31 is provided on the pinion shaft 30. The pinion 31 has a helical gear 31a (see reference). Figure 8 That is, the pinion 31 is called a helical gear. The pinion shaft 30 is rotatably supported on the pinion housing 11 via a first bearing 24 and a second bearing 25. The first bearing 24 supports the upper part of the pinion shaft 30. The second bearing 25 supports the lower part of the pinion shaft 30. Specifically, the first bearing 24 is provided on the cylindrical surface 32 on the upper side (D1 side, axial side) of the pinion 31.

[0045] A rack rod 40 is housed inside the rack housing 10. The rack rod 40 is formed into an axle shape extending in a predetermined direction, with its long side oriented in the vehicle width direction. The surface of the rack rod 40 at predetermined positions in the long side direction has a plurality of rack teeth 41. These rack teeth 41 are helical and arranged along the long side direction of the rack rod 40, meshing with the pinion 31 of the pinion shaft 30.

[0046] The tie rods 60 are respectively disposed on both sides of the rack 40 along its long side and are connected to the rack 40. Furthermore, the portion of the tie rod 60 opposite to the portion connected to the rack 40 on one side is connected to the wheel 65. Therefore, when the pinion shaft 30 rotates, the force along the long side of the rack 40 is transmitted to the rack teeth 41 meshing with the pinion 31, causing the rack 40 to move along its long side, i.e., moving in the vehicle width direction. As a result, the tie rods 60 move in the vehicle width direction, the orientation of the wheel 65 changes, and the vehicle's direction of travel changes.

[0047] The rack housing 10 is formed in a cylindrical shape, such that the axial direction of the cylinder is aligned along the long side of the rack rod 40. The rack housing 10, formed in this cylindrical shape, houses the rack rod 40 internally. The pinion housing 11 and the reducer housing 12 are integrally disposed within the rack housing 10.

[0048] The worm gear reducer 50 includes a worm shaft 52 and a worm wheel 51. The worm shaft 52 and worm wheel 51 are housed inside the reducer housing 12. The worm shaft 52 is located on the output shaft of the electric motor 53. The worm shaft 52 meshes with the worm wheel 51. The worm wheel 51 is fixed to the lower end of the pinion shaft 30. Therefore, when the electric motor 53 operates, the worm shaft 52 rotates, and the worm wheel 51 meshing with the worm shaft 52 rotates together with the pinion shaft 30. Thus, the electric motor 53 can impart auxiliary steering torque to the pinion shaft 30, reducing the force required to steer the steering wheel 20.

[0049] The ECU 80 is connected to a power supply unit 85 (e.g., an onboard battery), and power is supplied to the ECU 80 from the power supply unit 85. The ECU 80 controls the operation of the electric motor 53. The ECU 80 obtains signals from a torque sensor (not shown) and a vehicle speed sensor (not shown). The ECU 80 calculates an auxiliary steering command value based on the steering torque and vehicle speed. The ECU 80 adjusts the power supplied to the electric motor 53 based on the auxiliary steering command value. The ECU 80 obtains information about the induced voltage from the electric motor 53 or information output from a rotary transformer or similar device installed in the electric motor 53. By controlling the operation of the electric motor 53, as described above, the ECU 80 can apply auxiliary steering torque from the electric motor 53 to the pinion shaft 30, thereby reducing the force required to steer the steering wheel 20.

[0050] like Figure 1 As shown, the steering device 1 of this embodiment is an electric power steering device of the single pinion type that provides auxiliary force to the pinion shaft 30, but the steering device 1 is not limited to this. For example, the steering device 1 may also be a column-assisted type that provides auxiliary force to the first steering shaft 21, or a double-pinion type that has a second pinion (not shown) meshing with the rack 40 at a different position from the pinion 31 and provides auxiliary force to the second pinion. Alternatively, it may be a rack-assisted type electric power steering device that provides auxiliary force to the rack 40 without using a pinion, such as a ball screw type that provides auxiliary force to the rack 40 via a ball screw.

[0051] Figure 2 yes Figure 1 The diagram shows a front view of the rack bar 40 with a plurality of rack teeth 41. The rack bar 40 has a plurality of rack teeth 41 arranged along its long side. Furthermore, the rack teeth 41 are formed by helical teeth, thus each rack tooth 41 is formed obliquely relative to the long side direction of the rack bar 40. The plurality of rack teeth 41 arranged in this way allow for a plurality of spacings between the rack teeth 41 along the long side direction of the rack bar 40.

[0052] In detail, the rack tooth 41 has a wide-pitch portion 46 in which a plurality of rack teeth 41 are arranged at a predetermined interval, and a narrow-pitch portion 45 in which the spacing between the plurality of rack teeth 41 is narrower than the spacing between the rack teeth 41 located in the wide-pitch portion 46. That is, the spacing between the rack teeth 41 located in the wide-pitch portion 46 and the rack teeth 41 located in the narrow-pitch portion 45 are relatively different, and the spacing between the plurality of rack teeth 41 located in the wide-pitch portion 46 is wider than the spacing between the rack teeth 41 located in the narrow-pitch portion 45.

[0053] In this embodiment, the narrow-pitch portion 45 is disposed at three locations: the center and both ends of the rack tooth configuration range 44, which is the range in the long side direction of the rack 40 where a plurality of rack teeth 41 are disposed. The wide-pitch portion 46 is disposed at two locations: the narrow-pitch portion 45 at the center of the rack tooth configuration range 44 and the narrow-pitch portions 45 at both ends of the rack tooth configuration range 44, and between the narrow-pitch portions 45. For example, the narrow-pitch portion 45 is disposed in a range of approximately ±10 mm centered on the center of the rack tooth configuration range 44 in the long side direction of the rack 40, and in a range of approximately 10 mm from the end of the rack tooth configuration range 44. Furthermore, there may be a transition region at the boundary between the narrow-pitch portion 45 and the wide-pitch portion 46, which is a portion where the pitch of the rack teeth 41 gradually increases or decreases. In the case where the narrow pitch portion 45 includes transition regions where the pitch gradually increases or decreases, the narrow pitch portion 45 is disposed within a range of approximately ±25 mm centered on the center of the rack tooth configuration range 44 and within a range of approximately 25 mm from the end of the rack tooth configuration range 44.

[0054] Figure 3 It is configured in Figure 2 A detailed view of the rack teeth 41 of the wide-pitch portion 46 is shown. The thickness of the rack teeth 41 on the rack bar 40 decreases as they move from the base end side to the front end side. Furthermore, the rack teeth 41 located in the wide-pitch portion 46 have a fixed tooth thickness in the tooth width direction W, which is the direction in which the rack teeth 41 extend. That is, the surfaces on both sides of the rack teeth 41 in the tooth thickness direction T of the wide-pitch portion 46 are formed as flat portions 41a that are substantially flat along the tooth width direction W. Therefore, at any position of the rack teeth 41 in the wide-pitch portion 46 in the tooth width direction W, portions at the same height from the base end side have the same tooth thickness in the tooth thickness direction T.

[0055] Figure 4 It is configured in Figure 2 A detailed view of the rack tooth 41 of the narrow-pitch portion 45 is shown. The rack tooth 41 of the narrow-pitch portion 45 has a tooth thickness variation portion 42 on one side in the tooth thickness direction T, where the tooth thickness at the end in the tooth width direction W is less than the tooth thickness at the center in the tooth width direction W. In this embodiment, the tooth thickness variation portion 42 is formed by a so-called protrusion 43, where the tooth thickness is greatest at the center in the tooth width direction W and decreases towards the end in the tooth width direction W. Therefore, the surface of the rack tooth 41 of the narrow-pitch portion 45 on one side in the tooth thickness direction T is formed such that it curves towards the end in the tooth width direction W from the center towards both ends in the tooth width direction W, with the tooth thickness decreasing.

[0056] On the other hand, the tooth thickness variation portion 42 is not formed on the side opposite to the side of the rack tooth 41 in the narrow pitch portion 45 that has the tooth thickness variation portion 42, that is, the protrusion 43 is not formed. That is, the side of the rack tooth 41 in the narrow pitch portion 45 that does not have the protrusion 43 becomes a flat portion 41a that is formed approximately flat along the tooth width direction W. Therefore, the flat portions 41a in the rack tooth 41 in the narrow pitch portion 45 that are the side opposite to the side of the side with the tooth thickness variation portion 42 are formed to extend in a straight line in the tooth width direction W at the same height from the base end side.

[0057] A protrusion 43 on one side of the surface of the rack teeth 41 located in the narrow pitch portion 45 along the tooth thickness direction T is applied to the same side of the rack bar 40 in the long side direction relative to the plurality of rack teeth 41 located in the narrow pitch portion 45. That is, the protrusion 43 is applied to the same side of the rack bar 40 in the long side direction relative to the plurality of rack teeth 41 of the narrow pitch portion 45 located at the center of the rack tooth arrangement range 44 and the plurality of rack teeth 41 of the narrow pitch portions 45 located at both ends.

[0058] The function of the steering device 1 will now be explained. When the vehicle equipped with the steering device 1 is in motion, and the steering wheel 20 is operated, the steering force applied to the steering wheel 20 is transmitted from the steering wheel 20 to the first steering shaft 21. The steering force transmitted to the first steering shaft 21 is transmitted as a steering torque from the first steering shaft 21 to the second steering shaft 22, and from the second steering shaft 22 to the pinion shaft 30.

[0059] The pinion shaft 30 has a pinion 31 that meshes with the rack teeth 41 of the rack rod 40. The steering torque transmitted to the pinion shaft 30 is transmitted to the rack rod 40 through the pinion 31 of the pinion shaft 30 and the rack teeth 41 of the rack rod 40. The rack rod 40, which transmits steering torque from the pinion shaft 30, moves in the long side direction of the rack rod 40, which is the direction in which the plurality of rack teeth 41 are arranged. The rack rod 40 converts the steering torque transmitted from the pinion shaft 30 into linear motion in the long side direction of the rack rod 40 as described above. That is, the rack rod 40 moves in the vehicle width direction, which is the long side direction of the rack rod 40 disposed in the vehicle.

[0060] A tie rod 60 is connected to both ends of the rack 40. Therefore, as the rack 40 moves in the vehicle width direction, the tie rod 60 connected to the rack 40 also moves. Since the tie rod 60 is connected to the wheel 65, the orientation of the wheel 65 changes when the tie rod moves. As a result, the direction of travel of the vehicle equipped with the steering device 1 changes according to the operation of the steering wheel 20.

[0061] Furthermore, the steering device 1 in this embodiment includes an electric motor 53 that generates an auxiliary steering torque to assist the driver in steering. The electric motor 53 generates the auxiliary steering torque based on the steering torque detected by a torque sensor (not shown). Specifically, the steering torque detected by the torque sensor is transmitted as an electrical signal to the ECU 80, and the ECU 80 operates the electric motor 53 based on the electrical signal transmitted from the torque sensor, thereby causing the electric motor 53 to generate the auxiliary steering torque. The auxiliary steering torque generated by the electric motor 53 is transmitted to the pinion shaft 30 via a worm gear reducer 50.

[0062] That is, the auxiliary steering torque generated by the electric motor 53 is transmitted from the worm shaft 52 mounted on the output shaft of the electric motor 53 to the worm wheel 51 mounted on the pinion shaft 30 and meshing with the worm shaft 52, and then transmitted to the pinion shaft 30 via the worm wheel 51. Thus, the electric motor 53 assists the rotation of the pinion shaft 30, which rotates by steering torque, through the auxiliary steering torque generated by the electric motor 53. Therefore, the steering force applied by the driver to the steering wheel 20 is assisted by the auxiliary steering torque generated by the electric motor 53, and the force required to steer the steering wheel 20 is reduced due to the transmission of the auxiliary steering torque generated by the electric motor 53 to the pinion shaft 30.

[0063] Furthermore, the rack lever 40 has a plurality of rack teeth 41 with narrow-pitch portions 45 and wide-pitch portions 46. The narrow-pitch portions 45 are located at the center and both ends of the rack tooth arrangement range 44. That is, the narrow-pitch portions 45 are located near the center and near both ends of the rotation range of the steering wheel 20 that rotates the pinion 31 that meshes with the rack teeth 41. Therefore, the rack teeth 41 located in the narrow-pitch portions 45 mesh with the pinion 31 near the point of straight-line driving and near the point of maximum steering angle.

[0064] When the vehicle is traveling straight, the steering wheel 20 does not rotate significantly, but only slightly depending on the direction of travel, road conditions, or lane changes. Near this straight-moving distance, the pinion 31 meshes with the rack teeth 41 of the narrow-pitch section 45, thus reducing the amount of movement of the rack rod 40 along its long side relative to the rotation of the steering wheel 20 (i.e., the rotation of the pinion 31). Therefore, near straight-moving distance, the change in the orientation of the wheels 65 relative to the rotation of the steering wheel 20 is small, making it easier to make minor steering adjustments and ensuring good steering feel near straight-moving distances.

[0065] Furthermore, near the maximum steering angle when the vehicle is traveling, the orientation of wheel 65 changes significantly from its straight-ahead orientation. Therefore, when the vehicle is traveling in this state, wheel 65, which is turning from the road surface, exerts a large force to return the orientation of wheel 65 to its straight-ahead orientation. This large force to return the orientation of wheel 65 to its straight-ahead orientation is transmitted from wheel 65 to rack 40 via tie rod 60, and then from rack teeth 41 to pinion 31.

[0066] Therefore, near the maximum steering angle when the vehicle is traveling, a large force acts between the rack teeth 41 and the pinion 31. However, the rack teeth 41 of the rack rod 40 that mesh with the pinion 31 near the maximum steering angle are located in the narrow-pitch portion 45. Thus, near the maximum steering angle, the rack teeth 41 and the pinion 31 located in the narrow-pitch portion 45 mesh with the pinion 31. Therefore, compared to the case where the rack teeth 41 located in the wide-pitch portion 46 mesh with the pinion 31, the number of rack teeth 41 that are simultaneously in contact with the pinion 31 is increased.

[0067] Therefore, near the maximum steering angle, compared to the case where the rack teeth 41 located in the wide-pitch section 46 mesh with the pinion 31, a larger number of rack teeth 41 can withstand the greater force acting between the rack teeth 41 and the pinion 31. Thus, the stress on the rack teeth 41 near the maximum steering angle, where a large force acts between the rack teeth 41 and the pinion 31, can be reduced, ensuring durability.

[0068] Furthermore, at the steering angle between straight-line driving and the maximum steering angle, the pinion 31 meshes with the rack teeth 41 located in the wide-pitch section 46. In the wide-pitch section 46, the spacing of the rack teeth 41 is wider than that in the narrow-pitch section 45. Therefore, compared to the state where the pinion 31 meshes with the rack teeth 41 located in the narrow-pitch section 45, the amount of movement of the rack rod 40 along its long side relative to the rotation of the steering wheel 20 (i.e., the rotation of the pinion 31) is greater. Thus, at the steering angle between straight-line driving and the maximum steering angle, the change in the orientation of the wheel 65 relative to the rotation of the steering wheel 20 is greater, thereby improving steering responsiveness and ensuring a better steering feel when steering at a larger steering angle than when driving straight.

[0069] Furthermore, compared to the case where the rack teeth 41 located in the narrow-pitch portion 45 mesh with the pinion 31, when the rack teeth 41 located in the wide-pitch portion 46 mesh with the pinion 31, the number of rack teeth 41 simultaneously in contact with the pinion 31 is reduced. However, at steering angles smaller than near the maximum steering angle, the force acting between the rack teeth 41 and the pinion 31 is smaller than the force near the maximum steering angle. Therefore, even with fewer rack teeth 41 simultaneously in contact with the pinion 31 at steering angles smaller than near the maximum steering angle, the stress on the rack teeth 41 is less likely to increase, ensuring durability.

[0070] Furthermore, in this embodiment, the rack teeth 41 located in the wide-pitch portion 46 do not have protrusions 43, while the rack teeth 41 located in the narrow-pitch portion 45 have protrusions 43 on one side of their tooth thickness direction T. Therefore, the number of rack teeth 41 simultaneously in contact with the pinion 31 when the pinion 31 is engaged with the rack teeth 41 can be made as equal as possible throughout the entire area of ​​the rack tooth arrangement range 44. That is, when the pinion 31 is engaged with the rack teeth 41, the difference between the maximum and minimum number of teeth of the rack teeth 41 simultaneously in contact with the pinion 31 can be minimized as much as possible.

[0071] That is, the pinion 31 has a gear 31a with helical teeth (see reference). Figure 8 Since the rack tooth 41 is also a helical tooth, when the pinion 31's gear 31a contacts the rack tooth 41, the contact gradually begins from a position near the end of the gear 31a and the rack tooth 41 in the forming direction. For example, the rack tooth 41 gradually contacts the pinion 31's gear 31a from a position near its end in the tooth width direction W, and the contact position changes in the tooth width direction W depending on the rotation of the pinion 31.

[0072] Furthermore, the rack teeth 41 located in the narrow-pitch portion 45 have a narrower spacing compared to the rack teeth 41 located in the wide-pitch portion 46. Therefore, when the pinion 31 rotates and its gear 31a contacts the rack teeth 41, it is easier for the pinion 31 to contact the rack teeth 41 when it is located in the narrow-pitch portion 45 compared to the case where the pinion 31 is located in the wide-pitch portion 46.

[0073] Here, the rack tooth 41 located in the narrow pitch portion 45 has a protrusion 43 on one side of its tooth thickness direction T. Therefore, the pinion 31 is unlikely to make contact with the end near the tooth width direction W relative to the side of the rack tooth 41 with the protrusion 43. In addition, when the pinion 31 that is in contact with the side of the rack tooth 41 with the protrusion 43 located in the narrow pitch portion 45 leaves the rack tooth 41, it is easy to leave from the end near the tooth width direction W.

[0074] Therefore, the ease with which the rack teeth 41 located in the narrow-pitch portion 45 contact the pinion 31 due to their narrower pitch, and the difficulty with which the side of the rack teeth 41 with the protrusion 43 contacts the pinion 31 near its end in the tooth width direction W, are offset. As a result, the ease with which the rack teeth 41 located in the narrow-pitch portion 45 and the rack teeth 41 located in the wide-pitch portion 46 contact the rotating pinion 31 is approximately equal.

[0075] Therefore, in this embodiment, when the rotating pinion 31 meshes with the rack teeth 41, the difference between the maximum and minimum number of teeth of the rack teeth 41 that are simultaneously in contact with the pinion 31 becomes smaller overall within the rack tooth configuration range 44.

[0076] The following explains the change in the number of teeth of the rack 40 that are in simultaneous contact with the pinion 31 when the pinion 31 rotates. Figure 5 This is an explanatory diagram regarding the change in the number of teeth of the rack tooth 41 that is simultaneously in contact with the pinion 31 when the rack tooth 41 of the rack rod 40 without the protrusion 43 comes into contact with the rotating pinion 31. Figure 5 This is an explanatory diagram illustrating an example of the change in the number of rack teeth 41 simultaneously in contact with the pinion 31 when the portion of the rack tooth 41 in contact with the pinion 31 moves from one end of the rack tooth configuration range 44 to the other end. Furthermore, Figure 5 And the following Figure 6 , Figure 7 This is an explanatory diagram showing that a transition region 47 is provided between the narrow-pitch portion 45 and the wide-pitch portion 46 of the rack 40, which serves as a portion where the pitch of the rack teeth 41 changes between the two.

[0077] exist Figure 5 In the example shown, when the rack teeth 41 located in the narrow-pitch section 45 are in contact with the pinion 31, the number of rack teeth 41 simultaneously in contact with the pinion 31 varies between 3 and 5 due to the rotation of the pinion 31. On the other hand, when the rack teeth 41 located in the wide-pitch section 46 are in contact with the pinion 31, the number of rack teeth 41 simultaneously in contact with the pinion 31 varies between 2 and 3 due to the rotation of the pinion 31. Furthermore, when the rack teeth 41 located in the transition region 47 are in contact with the pinion 31, the number of rack teeth 41 simultaneously in contact with the pinion 31 varies between 3 and 4 due to the rotation of the pinion 31. Therefore, in Figure 5 In the example shown, the number of rack teeth 41 that are in contact with the pinion 31 varies between 2 and 5 depending on the position of contact between the pinion 31 and the rack teeth 41.

[0078] Figure 6This is an explanatory diagram regarding the change in the number of teeth of the rack teeth 41 that are simultaneously in contact with the pinion 31 when the rack teeth 41, which has protrusions 43 applied to both sides of the rack teeth 41, come into contact with the rotating pinion 31. Figure 6 This is an explanatory diagram illustrating an example of the change in the number of rack teeth 41 that simultaneously contact the pinion 31 when the portion of the rack teeth 41 that has protrusions 43 formed on both sides of the rack teeth 41 in contact with the pinion 31 moves from one end of the rack tooth configuration range 44 to the other end.

[0079] exist Figure 6 In the example shown, when the rack teeth 41 located in the narrow-pitch section 45 are in contact with the pinion 31, the number of rack teeth 41 simultaneously in contact with the pinion 31 varies between 2 and 4 due to the rotation of the pinion 31. On the other hand, when the rack teeth 41 located in the wide-pitch section 46 are in contact with the pinion 31, the number of rack teeth 41 simultaneously in contact with the pinion 31 varies between 1 and 2 due to the rotation of the pinion 31. Furthermore, when the rack teeth 41 located in the transition region 47 are in contact with the pinion 31, the number of rack teeth 41 simultaneously in contact with the pinion 31 varies between 1 and 3 due to the rotation of the pinion 31. Therefore, in Figure 6 In the example shown, the number of rack teeth 41 that are in contact with pinion 31 varies between one and four depending on the position of contact between pinion 31 and rack teeth 41.

[0080] Figure 7 This is an explanatory diagram regarding the change in the number of teeth of the rack tooth 41 that is simultaneously in contact with the pinion 31 when the rack tooth 41, which has a protrusion 43 on one side of the rack tooth 41 located in the narrow pitch portion 45, comes into contact with the rotating pinion 31. Figure 7 This is an explanatory diagram illustrating an example of the change in the number of rack teeth 41 that simultaneously contact the pinion 31 when the portion of the rack tooth 41 with a protrusion 43 applied to one side of the rack tooth 41 located in the narrow pitch portion 45 moves from one end of the rack tooth configuration range 44 to the other end.

[0081] exist Figure 7In the example shown, when the rack teeth 41 located in the narrow-pitch section 45 are in contact with the pinion 31, the number of rack teeth 41 simultaneously in contact with the pinion 31 varies between 3 and 4 due to the rotation of the pinion 31. On the other hand, when the rack teeth 41 located in the wide-pitch section 46 are in contact with the pinion 31, the number of rack teeth 41 simultaneously in contact with the pinion 31 varies between 2 and 3 due to the rotation of the pinion 31. Furthermore, even when the rack teeth 41 located in the transition region 47 are in contact with the pinion 31, the number of rack teeth 41 simultaneously in contact with the pinion 31 also varies between 2 and 3 due to the rotation of the pinion 31. Therefore, in Figure 7 In the example shown, the number of rack teeth 41 that are in contact with the pinion 31 varies between two and four depending on the position of contact between the pinion 31 and the rack teeth 41.

[0082] According to these Figure 5 , Figure 6 , Figure 7 As shown in the example, compared to the case where no protrusion 43 is provided on the rack tooth 41 and the case where protrusion 43 is provided on both sides of the rack tooth 41, the difference between the maximum and minimum number of teeth of the rack tooth 41 that simultaneously contacts the pinion 31 is smaller when a protrusion 43 is provided on only one side of the rack tooth 41 located in the narrow pitch portion 45. Therefore, compared to the case where no protrusion 43 is provided on the rack tooth 41 and the case where protrusion 43 is provided on both sides of the rack tooth 41, the variation in steering resistance during steering can be reduced when a protrusion 43 is provided on only one side of the rack tooth 41 located in the narrow pitch portion 45.

[0083] In addition, according to Figure 5 , Figure 7 As can be seen from the example, compared to the case where the rack teeth 41 do not have a protrusion 43, when a protrusion 43 is provided on one side of the rack teeth 41 located in the narrow pitch portion 45, the maximum number of rack teeth 41 that simultaneously contact the pinion 31 is reduced. Therefore, compared to the case where the rack teeth 41 do not have a protrusion 43, when a protrusion 43 is provided on one side of the rack teeth 41 located in the narrow pitch portion 45, the steering resistance during steering can be reduced.

[0084] As described above, in the steering device 1 of this embodiment, the rack 40 has rack teeth 41 with a wide pitch portion 46 and a narrow pitch portion 45. The rack teeth 41 located in the narrow pitch portion 45 have a tooth thickness variation portion 42 on one side in the tooth thickness direction T, where the tooth thickness at the end in the tooth width direction W is smaller than the tooth thickness at the center in the tooth width direction W. Therefore, when the rotating pinion 31 contacts the rack teeth 41 located in the narrow pitch portion 45, it is difficult to make contact near the end of the rack teeth 41 in the tooth width direction W. Thus, the rack teeth 41 located in the narrow pitch portion 45 can offset the ease of contact with the pinion 31 due to the narrow pitch and the difficulty of contacting the pinion 31 near the end in the tooth width direction W. Therefore, by reducing the difference between the maximum and minimum number of teeth of the rack teeth 41 that simultaneously contact the pinion 31 across the entire rack tooth configuration range 44, unlike Patent Document 1 which reduces the diameter of the rack rod 40 locally, thus minimizing the change in sliding resistance between the rack rod 40 and the rack bushing (not shown), the variation in steering resistance during steering can be reduced. Consequently, the variation in steering resistance during steering can be suppressed without reducing the rigidity of the rack rod 40.

[0085] Furthermore, the tooth thickness variation portion 42 of the rack teeth 41 located in the narrow-pitch portion 45 is a protrusion 43 whose tooth thickness decreases from the center towards the end in the tooth width direction W of the rack teeth 41. Therefore, when the rotating pinion 31 contacts the rack teeth 41 located in the narrow-pitch portion 45, it is difficult to make contact near the end in the tooth width direction W. Thus, the ease of contact between the rack teeth 41 located in the narrow-pitch portion 45 and the pinion 31 due to the narrow pitch, and the difficulty of contact near the end in the tooth width direction W of the rack teeth 41 due to the protrusion 43, can be offset. Therefore, the difference between the maximum and minimum number of teeth of the rack teeth 41 that are in contact with the pinion 31 simultaneously can be reduced, and the variation in steering resistance during steering can be reduced. As a result, the variation in steering resistance during steering can be suppressed without reducing the rigidity of the rack rod 40.

[0086] Furthermore, the narrow-pitch portion 45 is disposed at the center and both ends of the rack tooth arrangement range 44. Therefore, the narrow-pitch portion 45 at the center ensures steering feel near straight-line driving, and the narrow-pitch portions 45 at both ends reduce stress on the rack teeth 41 near the maximum steering angle, thus ensuring durability. Additionally, since the wide-pitch portion 46 is disposed between the center and the narrow-pitch portions 45 at both ends along the long side of the rack 40, the wide-pitch portion 46 improves the steering angle responsiveness relative to steering between straight-line driving and the maximum steering angle, ensuring steering feel when steering at a larger steering angle than during straight-line driving. As a result, both the steering feel during vehicle operation and the durability of the rack 40 can be improved simultaneously.

[0087] Furthermore, the number of rack teeth 41 in simultaneous contact with pinion 31 is between two and four, thus suppressing changes in steering resistance and impact noise during steering, thereby improving steering feel. In other words, the number of rack teeth 41 in simultaneous contact with pinion 31 is two or more, thereby suppressing impact noise and improving steering feel.

[0088] Figure 8 This is an explanatory diagram showing the contact state between the two rack teeth 41 and the pinion 31 (gear 31a). When both rack teeth 41 are in contact with the pinion 31 simultaneously, as shown... Figure 8 As shown, the two rack teeth 41 contact the gear 31a on both sides of the gear 31a of the pinion 31 in the tooth thickness direction. Therefore, while the gear 31a of the rotating pinion 31 is located on the rack shank 40 side, the rack teeth 41 and the two sides of the gear 31a can be in continuous contact, which can suppress the impact noise generated when the gear 31a of the separated pinion 31 contacts the rack teeth 41. In addition, by making the two rack teeth 41 contact the two sides of the gear 31a of the pinion 31, the backlash between the pinion 31 and the rack shank 40 can be reduced, and the steering feel during steering can be improved.

[0089] Furthermore, the number of rack teeth 41 in simultaneous contact with pinion 31 is four or less. This reduces the difference between the maximum and minimum number of rack teeth 41 in simultaneous contact with pinion 31, thereby reducing fluctuations in steering resistance during steering. As a result, it suppresses changes in steering resistance during steering, reduces impact noise, and improves steering feel.

[0090] [Variation Example]

[0091] Furthermore, in the above embodiment, the narrow pitch portion 45 is disposed at the center and both ends of the rack tooth configuration range 44, but the narrow pitch portion 45 may also be disposed at other positions. Figure 9 This is a variation of the steering device 1 of the embodiment, and is a schematic diagram showing a narrow-pitch portion 45 arranged in the center of the rack tooth arrangement range 44. For example, as Figure 9 As shown, the narrow pitch portion 45 may also be disposed in the center of the rack tooth arrangement range 44, while the narrow pitch portion 45 is not disposed at either end of the rack tooth arrangement range 44. In this case, the wide pitch portion 46 is disposed in the entire area on both sides of the narrow pitch portion 45 in the rack tooth arrangement range 44.

[0092] For example, if the load on the rack teeth 41 during steering is relatively small and lightweight due to the vehicle equipped with the steering device 1, the force acting between the rack teeth 41 and the pinion 31 is unlikely to increase even near the maximum steering angle. In such cases, since the stress on the rack teeth 41 is unlikely to increase even near the maximum steering angle, the narrow-pitch portions 45 can be omitted at both ends of the rack tooth arrangement range 44, resulting in wide-pitch portions 46. Thus, even with a relatively small load on the rack teeth 41 near the maximum steering angle, by also providing wide-pitch portions 46 near both ends of the rack tooth arrangement range 44, the responsiveness when steering at a larger steering angle can be improved, thus enhancing the steering feel.

[0093] In addition, in the above embodiment, the rack tooth 41 located in the narrow pitch portion 45 has a tooth thickness variation portion 42 on one side of the tooth thickness direction T, while the rack tooth 41 located in the wide pitch portion 46 does not have a tooth thickness variation portion 42. However, the rack tooth 41 located in the narrow pitch portion 45 and the rack tooth 41 located in the wide pitch portion 46 may also be formed in other ways.

[0094] Figure 10 This is a variation of the steering device 1 of the embodiment, and is an explanatory diagram showing the manner in which a tooth thickness variation portion 42 is formed on one side of the rack tooth 41 disposed in the wide-pitch portion 46. Figure 11 This is a variation of the steering device 1 of the embodiment, and is an explanatory diagram showing a method in which tooth thickness variation portions 42 are formed on both sides of the rack teeth 41 disposed in the narrow-pitch portion 45. For example, it can also be as follows: Figure 10 As shown, the rack tooth 41 located in the wide-pitch portion 46 has a tooth thickness variation portion 42 on one side of its surface in the tooth thickness direction T, and the other side of its surface is a flat portion 41a. For example, it can also be as follows: Figure 11 As shown, the rack tooth 41 located in the narrow pitch portion 45 has tooth thickness variation portions 42 on both sides of its tooth thickness direction T. That is, the rack tooth 41 located in the wide pitch portion 46 may also have a protrusion 43 on one side of its tooth thickness direction T as a tooth thickness variation portion 42, and the rack tooth 41 located in the narrow pitch portion 45 may also have a protrusion 43 on both sides of its tooth thickness direction T as a tooth thickness variation portion 42.

[0095] In this way, by forming a tooth thickness variation portion 42 on one side of the rack tooth 41 located in the wide pitch portion 46 and forming a tooth thickness variation portion 42 on both sides of the rack tooth 41 located in the narrow pitch portion 45, the difference between the maximum number of teeth and the minimum number of teeth of the rack tooth 41 that is in contact with the pinion 31 at the same time can be reduced.

[0096] That is, the ease with which the rack teeth 41 located in the narrow pitch portion 45 can contact the pinion 31 due to their narrower pitch than the wide pitch portion 46, and the difficulty with which they can contact the pinion 31 due to the larger surface area of ​​the tooth thickness variation portion 42 compared to the rack teeth 41 located in the wide pitch portion 46, can be offset. In other words, the difficulty with which the rack teeth 41 located in the wide pitch portion 46 can contact the pinion 31 due to their wider pitch than the narrow pitch portion 45, and the ease with which they can contact the pinion 31 due to the smaller surface area of ​​the tooth thickness variation portion 42 compared to the rack teeth 41 located in the narrow pitch portion 45, can be offset.

[0097] Therefore, by reducing the difference between the maximum and minimum number of teeth of the rack teeth 41 that are simultaneously in contact with the pinion 31 throughout the rack tooth configuration range 44, the variation in steering resistance during steering can be reduced. As a result, the variation in steering resistance during steering can be suppressed without reducing the rigidity of the rack rod 40.

[0098] Furthermore, in the above embodiment, the tooth thickness variation portion 42 of the rack tooth 41 is formed by the protrusion 43, but the tooth thickness variation portion 42 may also be formed by a portion other than the protrusion 43. For example, the tooth thickness variation portion 42 may be a so-called end thinning where the tooth thickness near the center in the tooth width direction W of the rack tooth 41 is fixed, and the tooth thickness at the end in the tooth width direction W is formed to be smaller than the tooth thickness at the center in the tooth width direction W. The tooth thickness variation portion 42 is not limited in shape as long as the tooth thickness at the end in the tooth width direction W of the rack tooth 41 is smaller than the tooth thickness at the center in the tooth width direction W.

[0099] The preferred embodiments of this disclosure have been described above, but this disclosure is not limited to the contents described in the above embodiments. The structures described as embodiments and variations can also be appropriately combined.

[0100] Label Explanation

[0101] 1: Steering mechanism; 10: Rack housing; 11: Pinion housing; 12: Reducer housing; 20: Steering wheel; 21: First steering shaft; 22: Second steering shaft; 24: First bearing; 25: Second bearing; 26: First universal joint; 27: Second universal joint; 30: Pinion shaft; 31: Pinion; 31a: Gear; 32: Cylindrical surface; 40: Rack rod; 41: Rack tooth; 41a: Flat portion; 42: Tooth thickness variation portion; 43: Protrusion; 44: Rack tooth configuration range; 45: Narrow pitch portion; 46: Wide pitch portion; 47: Transition area; 50: Worm gear reducer; 51: Worm wheel; 52: Worm shaft; 53: Electric motor; 60: Tie rod; 65: Wheel; 80: ECU; 85: Power supply unit.

Claims

1. A steering device, wherein, The steering device includes: A pinion, which is a gear with helical teeth; and A rack rod having a plurality of helical teeth that mesh with the pinion. The rack teeth have: a wide-pitch portion, in which a plurality of rack teeth are arranged at a predetermined spacing; and a narrow-pitch portion, wherein the spacing between the plurality of rack teeth in the narrow-pitch portion is narrower than the spacing between the rack teeth located in the wide-pitch portion. The rack teeth located in the wide-spacing portion have a fixed tooth thickness in the tooth width direction. The rack tooth located in the narrow pitch section has a tooth thickness variation section on one side of the tooth thickness direction, and the tooth thickness at the end of the tooth thickness variation section in the tooth width direction is smaller than the tooth thickness at the center in the tooth width direction.

2. A steering device, wherein, The steering device includes: A pinion, which is a gear with helical teeth; and A rack rod having a plurality of helical teeth that mesh with the pinion. The rack teeth have: a wide-pitch portion, in which a plurality of rack teeth are arranged at a predetermined spacing; and a narrow-pitch portion, wherein the spacing between the plurality of rack teeth in the narrow-pitch portion is narrower than the spacing between the rack teeth located in the wide-pitch portion. The rack tooth located in the wide-pitch portion has a tooth thickness variation portion on one side in the tooth thickness direction, where the tooth thickness at the end in the tooth width direction is smaller than the tooth thickness at the center in the tooth width direction. The rack teeth located in the narrow pitch section have tooth thickness variation sections on both sides of the tooth thickness direction.

3. The steering device according to claim 1 or 2, wherein, The tooth thickness variation section is a protrusion with the largest tooth thickness at the center in the tooth width direction, which decreases in thickness towards the end in the tooth width direction.

4. The steering device according to any one of claims 1 to 3, wherein, The narrow-pitch portion is disposed at the center and both ends of the area in the long side direction of the rack bar where multiple rack teeth are disposed. The wide-spacing portion is disposed at the center of the rack bar along its long side and between the narrow-spacing portions at both ends.

5. The steering device according to any one of claims 1 to 3, wherein, The narrow-pitch portion is located at the center of the area in the long side direction of the rack bar where the plurality of rack teeth are arranged. The wide-spacing portion is disposed on both sides of the narrow-spacing portion in the long side direction of the rack.

6. The steering device according to any one of claims 1 to 5, wherein, The number of rack teeth that are in simultaneous contact with the pinion is between two and four.

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