Steering device

Abstract

An electric power steering device (100) includes a rack shaft (30) for steering a wheel (1), a gear housing (70) as a housing that houses the rack shaft (30) and has an opening portion (71) through which the rack shaft (30) protrudes, a sheath (80) that covers the opening portion (71) of the gear housing (70), and a sheath belt (90) as a ring-shaped belt portion that presses and fixes the sheath (80) toward an outer peripheral surface (72) of the gear housing (70), the gear housing (70) having a pressed portion (75) pressed by the sheath belt (90) in the outer peripheral surface (72) and a ring-shaped protruding portion (76, 77, 78, 79) that protrudes from the pressed portion (75) in a radial direction of the opening portion (71).

Description

Technical Field

[0001] This invention relates to a steering device. Background Technology

[0002] In the steering device described in Japanese Patent Application Publication JP2020-171105A, a cylindrical sheath is installed on the gear housing. The sheath is fastened to the cylindrical portion of the gear housing by a sheath belt. Summary of the Invention

[0003] In this steering mechanism, a sheath is secured to the cylindrical portion of the gear housing via a sheath belt, thereby preventing foreign objects from entering the gear housing through the gap between the gear housing and the sheath. However, when the outer circumferential surface of the cylindrical portion of the gear housing to which the sheath is secured is flat in the axial section, the contact surface between the gear housing and the sheath becomes straight in that section. Therefore, there is a possibility that a high level of sealing cannot be achieved between the gear housing and the sheath.

[0004] The present invention was made in view of the above-mentioned problems, and its object is to improve the sealing performance between the housing and the sheath of the steering device.

[0005] According to one aspect of the present invention, a steering device comprises: a rack shaft for changing the direction of a wheel; a housing for receiving the rack shaft and having an opening for the rack shaft to protrude; a sheath covering the opening of the housing; and an annular band pressing and fixing the sheath toward the outer peripheral surface of the housing, the housing having a pressed portion in the outer peripheral surface pressed by the band and an annular protrusion protruding radially from the pressed portion toward the opening. Attached Figure Description

[0006] Figure 1 This is a structural diagram of the electric power steering device according to an embodiment of the present invention.

[0007] Figure 2 This is an enlarged sectional view of the gear housing and sheath.

[0008] Figure 3 This is an enlarged sectional view of the fixing part between the gear housing and the sheath.

[0009] Figure 4 The fixing part of the gear housing and the sheath involved in the modified example. Figure 3 The corresponding enlarged sectional view. Detailed Implementation

[0010] Referring to the accompanying drawings, an electric power steering device 100, which is a steering device according to an embodiment of the present invention, will be described.

[0011] like Figure 1As shown, the electric power steering device 100 is provided with a steering shaft 20 that rotates by a steering torque input from a steering wheel 10, and a rack shaft 30 that turns a wheel 1 in conjunction with the rotation of the steering shaft 20 as a turning shaft.

[0012] The steering shaft 20 is composed of an input shaft 21 that rotates in conjunction with a steering operation by a driver operating the steering wheel 10, an output shaft 22 that displaces the rack shaft 30, and a torsion bar 23 that links the input shaft 21 and the output shaft 22.

[0013] The rack shaft 30 is an axis-like member provided in a manner extending in the left-right direction of the wheel, and is linked to one wheel 1 via a first tie rod 41a and a first knuckle arm 42a. Also, the rack shaft 30 is linked to the other wheel 1 via a second tie rod 41b and a second knuckle arm 42b.

[0014] The first tie rod 41a and the second tie rod 41b are linked to the rack shaft 30 in a manner each freely swingable via first and second ball joints 43a and 43b as linking portions provided at both end portions of the rack shaft 30. Also, as the linking portions linking the rack shaft 30 and the first and second tie rods 41a and 41b, the first and second ball joints 43a and 43b are not limited thereto, and other forms of universal joints can be used.

[0015] The output shaft 22 and the rack shaft 30 are linked to each other via a gear rack mechanism composed of a pinion 22a provided at an end portion of the output shaft 22 and a rack gear 30a provided at the rack shaft 30. The pinion 22a and the rack gear 30a are engaged with each other, and the torque of the output shaft 22 is converted into a load in the axial direction of the rack shaft 30 via the pinion 22a and the rack gear 30a, and is transmitted to the rack shaft 30. By this, the rack shaft 30 is displaced in the axial direction by the transmitted torque, and turns the wheel 1 via the first and second tie rods 41a and 41b.

[0016] Also, the electric power steering device 100 is provided with an electric motor 50 that is driven to assist a steering force in accordance with a steering operation, and a reduction portion 52 that reduces the rotation of the electric motor 50 and transmits it to the steering shaft 20.

[0017] The reduction portion 52 is a worm gear mechanism composed of a worm shaft 53 driven by the electric motor 50 and a worm wheel 54 provided at the output shaft 22. The worm shaft 53 and the worm wheel 54 are engaged with each other, and the torque of the electric motor 50 is transmitted to the output shaft 22 via the worm shaft 53 and the worm wheel 54. The torque transmitted from the electric motor 50 to the output shaft 22 is further transmitted to the rack shaft 30 via the pinion 22a and the rack gear 30a.

[0018] Further, the electric power steering apparatus 100 further includes a torque sensor 62 that detects a torque applied to the torsion bar 23, and a controller 60 that controls driving of the electric motor 50 based on a detection value of the torque sensor 62.

[0019] The controller 60 is constituted by a microcomputer including a CPU (Central Processing Unit) that performs arithmetic processing, a ROM (Read-Only Memory) that stores a control program or the like executed by the CPU, and a RAM (random access memory) that stores an arithmetic result or the like of the CPU. The controller 60 can be constituted by a single microcomputer or a plurality of microcomputers.

[0020] The torque sensor 62 detects a steering torque applied to the input shaft 21 in association with a steering operation performed by the driver, and outputs a signal corresponding to the detected steering torque to the controller 60. The controller 60 calculates a torque output by the electric motor 50 based on the signal from the torque sensor 62, and controls driving of the electric motor 50 in such a manner that the torque is generated.

[0021] Thus, in the electric power steering apparatus 100 having the above-described structure, the steering operation of the driver can be assisted by detecting the steering torque applied to the input shaft 21 by the torque sensor 62, and controlling driving of the electric motor 50 by the controller 60 based on the detection result.

[0022] As shown in FIG. 1, the electric power steering apparatus 100 includes a steering wheel 10, a steering column 20, a steering shaft 40, a torsion bar 23, an electric motor 50, and a rack-and-pinion mechanism 60. Figure 2 As shown in FIG. 1, the electric power steering apparatus 100 includes a steering wheel 10, a steering column 20, a steering shaft 40, a torsion bar 23, an electric motor 50, and a rack-and-pinion mechanism 60.

[0023] The electric power steering apparatus 100 includes a sheath 80a, 80b that covers the opening portions 71a, 71b of the gear housing 70, and a sheath belt 90a, 90b that is a belt portion in a ring shape, which presses and fixes the sheath 80a, 80b toward the outer peripheral surface 72 of the gear housing 70. The sheath 80a, 80b covers the rack shaft 30 and the first and second tie rods 41a, 41b (see FIG. 2) protruding from the opening portions 71a, 71b of the gear housing 70, respectively. Figure 1In this way, the sheaths 80a and 80b protect the rack shaft 30, the first tie rod 41a, and the second tie rod 41b from foreign objects. Furthermore, the sheaths 90a and 90b are formed to a predetermined length in the axial direction and are respectively fastened to the outer peripheral surface 72 of the gear housing 70. Thus, the openings 71a and 71b are covered by the sheaths 80a and 80b, thereby preventing foreign objects from entering the gear housing 70 through the openings 71a and 71b.

[0024] The structures near openings 71a and 71b, sheaths 80a and 80b, and sheath bands 90a and 90b are identical. Therefore, the following... Figure 2 The structure of the area near the opening 71a on the left side, the sheath 80a, and the sheath band 90a will be described. The structure of the area near the opening 71b, the sheath 80b, and the sheath band 90b will be omitted from the description. In addition, the opening 71a will be referred to as "opening 71", the sheath 80a as "sheath 80", and the sheath band 90a as "sheath band 90" below.

[0025] The gear housing 70 has: a receiving hole 73 for receiving the rack shaft 30; a recess 74 formed on the outer peripheral surface 72, and a sheath band 90 and a sheath 80 are mounted in the recess 74. The receiving hole 73 extends through the gear housing 70 and forms an opening 71 at its end. The rack shaft 30 is inserted through the receiving hole 73 and protrudes from the opening 71. The recess 74 is formed annularly near the opening 71, and its axial length is longer than the axial length of the sheath band 90. That is, on the outer peripheral surface 72 of the gear housing 70, a portion of the recess 74 is pressed radially inward by the sheath band 90. In other words, the gear housing 70 has a pressed portion 75 in the outer peripheral surface 72 that is pressed by the sheath band 90. Specifically, the pressed portion 75 refers to the region in the recess 74 located radially inward of the sheath band 90.

[0026] like Figure 3 As shown, an annular protrusion 76 is formed on the recess 74, protruding radially from the pressed portion 75 into the opening 71. In other words, the protrusion 76 is formed between the two ends of the pressed portion 75 in the axial direction of the opening 71. In this embodiment, two protrusions 76 of the same shape are formed near the center of the recess 74 at axial intervals.

[0027] The protrusion 76 has a wall portion 76a extending perpendicularly to the axial direction of the opening portion 71 from the bottom surface of the recessed portion 74 of the gear housing 70, a tapered portion 76b extending from the bottom surface of the recessed portion 74 toward the wall portion 76a in a manner away from the opening portion 71, and a connecting portion 76c connecting the wall portion 76a and the tapered portion 76b. Specifically, the wall portion 76a protrudes from the pressed portion 75 of the outer circumferential surface 72 in the radial direction of the opening portion 71. The tapered portion 76b is formed in a manner in which the amount of protrusion in the radial direction of the opening portion 71 increases as it approaches the wall portion 76a. The connecting portion 76c is provided in the axial direction of the opening portion 71. That is, the protrusion 76 is formed in a manner in which the cross section in the axial direction of the opening portion 71 is trapezoidal. In addition, the bottom surface of the recessed portion in which the wall portion 76a and the tapered portion 76b extend is a portion of the outer circumferential surface 72.

[0028] The tapered portion 76b is provided on the opening portion 71 side of the gear housing 70 compared to the wall portion 76a. Specifically, when using the opening portion 71a and the opening portion 71b to explain, at the protrusion 76 of the recessed portion 74 formed near the opening portion 71a, the tapered portion 76b is provided on the opening portion 71a side compared to the wall portion 76a. In addition, although not shown, at the protrusion of the recessed portion formed near the opening portion 71b, the tapered portion is provided on the opening portion 71b side compared to the wall portion.

[0029] The sheath 80 is, for example, a meandering cylindrical member formed of rubber or resin. The sheath 80 is capable of expanding and contracting in the axial direction of the rack shaft 30 in a manner that can follow the reciprocating movement of the rack shaft 30. The sheath 80 has a body portion 81 and a ring-shaped mounting portion 82 provided at the end portion of the body portion 81 and mounted to the gear housing 70. The inner circumferential surface of the mounting portion 82 abuts against the bottom surface of the recessed portion 74 of the gear housing 70. At the end portion of the mounting portion 82 on the opposite side from the body portion 81, a flange portion 83 protruding to the radial direction outside of the mounting portion 82 is formed. A housing space 84 capable of housing the sheath band 90 is formed at the outer circumferential surface of the mounting portion 82 by the boundary between the body portion 81 and the mounting portion 82 and the flange portion 83. The housing space 84 is formed in a recessed manner in a manner capable of housing the sheath band 90, and the length in the axial direction is formed to be longer than the length in the axial direction of the sheath band 90. After the sheath 80 is mounted to the gear housing 70 from the opening portion 71 side in a manner in which the inner circumferential surface of the mounting portion 82 is housed in the recessed portion 74, the sheath band 90 is mounted to the housing space 84. Then, it is fastened and fixed to the recessed portion 74 of the gear housing 70. The other end portion of the sheath 80 is fixed to the first pull rod 41a.

[0030] Thus, when the boot 80 is fastened to the gear housing 70 by the boot band 90, the boot 80 is pressed toward the protruding portion 76 of the gear housing 70. Therefore, a load from the boot band 90 is easily applied to the boot 80 at the protruding portion 76, compared to other portions of the pressed portion 75. Thus, the contact surface pressure of the gear housing 70 and the boot 80 is increased by the protruding portion 76, so that the protruding portion 76 of the gear housing 70 is brought into close contact with the boot 80. In the present embodiment, the contact surface pressure of the gear housing 70 and the boot 80 is increased by the corner between the wall portion 76a and the connecting portion 76c, so that the gear housing 70 and the boot 80 are brought into close contact. Thus, the sealing property between the gear housing 70 and the boot 80 is improved.

[0031] Further, in a case where the gear housing does not have a protruding portion, the gear housing and the boot are in contact through a cylindrical surface, and the contact surface of the gear housing and the boot is linear in a cross section in the axial direction of the opening portion. In this structure, the intrusion path of a foreign object that intrudes into the gear housing via between the gear housing and the boot is short. In contrast, since the gear housing 70 of the electric power steering apparatus 100 in the present embodiment has the protruding portion 76, the intrusion path of a foreign object that intrudes into the gear housing 70 via between the gear housing 70 and the boot 80 is long. Thus, the sealing property between the gear housing 70 and the boot 80 is improved.

[0032] Therefore, for example, even in a case where the electric power steering apparatus 100 is subjected to muddy water, or in a case where it is subjected to salt water due to quality tests, since the sealing property between the gear housing 70 and the boot 80 is high, the progress of corrosion of the aluminum gear housing 70 due to intrusion of muddy water or salt water into the gear housing 70 is also suppressed.

[0033] Further, the tapered portion 76b of the protruding portion 76 that extends toward the wall portion 76a is provided on the opening portion 71 side of the gear housing 70, compared to the wall portion 76a. Specifically, at the protruding portion 76 provided by the recess 74 near the opening portion 71a, the tapered portion 76b is provided on the opening portion 71a side, compared to the wall portion 76a. Further, at the protruding portion 76 provided by the recess 74 near the opening portion 71b, the tapered portion 76b is provided on the opening portion 71b side, compared to the wall portion 76a. Thus, when the boot 80 is attached to the gear housing 70 from the opening portion 71 side, the boot 80 can easily pass over the protruding portion 76 by the tapered portion 76b, so that the attachment of the boot 80 to the gear housing 70 is not hindered by the protruding portion 76. Further, since the attached boot 80 is caught by the wall portion 76a, the case where the boot 80 is detached from the gear housing 70 is prevented.

[0034] According to the above-described present embodiment, the following effects are exhibited.

[0035] Because the sleeve 80 is pressed against the protrusion 76 of the gear housing 70 in the electric power steering device 100, the protrusion 76 is more susceptible to load from the sleeve band 90 compared to other parts of the pressed portion 75. Therefore, the contact surface pressure between the gear housing 70 and the sleeve 80 is increased due to the protrusion 76, allowing the protrusion 76 of the gear housing 70 to fit tightly against the sleeve 80. In this embodiment, the contact surface pressure between the gear housing 70 and the sleeve 80 is increased due to the corner between the wall portion 76a and the connecting portion 76c, resulting in a tight fit between the housing 70 and the sleeve 80. This improves the sealing performance between the gear housing 70 and the sleeve 80.

[0036] Because the gear housing 70 has a protrusion 76, the intrusion path of foreign objects that wish to enter the gear housing 70 through the space between the gear housing 70 and the sheath 80 is lengthened. As a result, the sealing performance between the gear housing 70 and the sheath 80 can be improved.

[0037] A tapered portion 76b extending toward the wall portion 76a from the protrusion 76 is provided on the side closer to the opening 71a of the gear housing 70 than the wall portion 76a. Therefore, when the sheath 80 is installed onto the gear housing 70 from the opening 71a side, the sheath 80 can easily pass over the protrusion 76 via the tapered portion 76b, and thus the installation of the sheath 80 onto the gear housing 70 is not obstructed by the protrusion 76. In addition, since the installed sheath 56 is locked to the wall portion 76a, the sheath 80 is prevented from falling off the gear housing 70.

[0038] Next, variations of this embodiment will be described.

[0039] <Variation Example 1>

[0040] In the above embodiment, as protrusions, two protrusions 76 of the same shape are provided near the center of the pressed portion 75 in a manner spaced apart axially. However, for example, as... Figure 4As shown, three protrusions 77, 78, 79 having different shapes can also be formed as the protrusions. Specifically, the electric power steering apparatus 100 can also have the following structure, that is, as the protrusions, the protrusion 77 as the first protrusion and the protrusions 78 and 79 as the second protrusions are provided, the protrusions 78 and 79 are disposed in such a manner as to be farther from the center of the pressed portion 75 in the axial direction of the opening portion 71 than the protrusion 77. The protrusion 77 is disposed, for example, near the center of the pressed portion 75. The protrusion 78 is disposed on the opening portion 71 side relative to the protrusion 77, and the protrusion 79 is formed on the side opposite to the protrusion 78 relative to the protrusion 77. That is, the protrusions 78 and 79 are disposed on the end portion side of the pressed portion 75 in the axial direction of the opening portion 71 than the protrusion 77.

[0041] The protrusion 77 has the wall portion 77a, the tapered portion 77b, and the connecting portion 77c, like the protrusion 76 in the above-described embodiment. The protrusion 78 has the wall portion 78a extending perpendicularly to the axial direction of the opening portion 71 from the pressed portion 75, and the tapered portion 78b extending from the pressed portion 75 toward the wall portion 78a in such a manner as to be farther from the opening portion 71, the wall portion 78a and the tapered portion 78b being continuous. The protrusion 79 has the wall portion 79a and the tapered portion 79b, like the protrusion 78. The protrusions 78 and 79 have protrusion amounts in the radial direction of the opening portion 71 from the recessed portion 74 that are formed to be greater than the protrusion amount of the protrusion 77 in the radial direction of the opening portion 71 from the recessed portion 74. Specifically, the lengths of the wall portions 78a and 79a in the radial direction of the opening portion 71 are formed to be longer than the wall portion 77a. Thus, the protrusions 78 and 79 disposed on the end portion side of the pressed portion 75 than the protrusion 77 have greater protrusion amounts in the radial direction of the opening portion 71, and thus, loads from the sheath belt 90 are likely to act thereon than the protrusion 77. Therefore, the contact surface pressure of the gear housing 70 against the sheath 80 is high on the end portion side of the pressed portion 75.

[0042] Here, the inner peripheral surface of the mounting portion 82 of the sheath 80 abuts against the bottom surface of the recessed portion 74 of the gear housing 70. Thus, the sheath 80 is thick on the central side in the axial direction of the recessed portion 74 and is thin on the both end portion sides in the axial direction of the recessed portion 74. In other words, the sheath 80 is likely to be thin on the both end portion sides of the pressed portion 75. Since the contact surface pressure of the gear housing 70 against the sheath 80 is low at the portions of the sheath 80 where the sheath 80 is thin compared to the portions of the sheath 80 where the sheath 80 is thick, the sealing property between the gear housing 70 and the sheath 80 can be reduced. However, since the contact surface pressure of the gear housing 70 against the sheath 80 is high on the end portion side of the pressed portion 75 of the sheath 80 where the sheath 80 is likely to be thin in the present modified example, the sealing property between the gear housing 70 and the sheath 80 can be effectively improved.

[0043] Further, the protrusions 78, 79 can be formed only on either side. Further, in a case where four or more protrusions are formed, the protrusion amount in the radial direction of the opening portion 71 of an arbitrary protrusion and a protrusion disposed further from the center of the pressed portion 75 in the axial direction of the opening portion 71 is compared, and the protrusion amount of the latter is made larger. Even in the above structure, the sealing property between the gear housing 70 and the sheath 80 can be effectively improved as in the above.

[0044] <Modification Example 2>

[0045] In the above embodiment, as the protrusions, the protrusions 76 of the same shape are provided in two. However, the number of protrusions can be one or three or more. In a case where the number of protrusions is plural, the protrusions can be disposed at intervals in the axial direction. In this way, by adjusting the number of protrusions, the number of times the gear housing 70 and the sheath 80 are in close contact, the length of the intrusion path of foreign matter that intrudes into the gear housing 70 via between the gear housing 70 and the sheath 80 can be adjusted step by step. Thus, the sealing property between the gear housing 70 and the sheath 80 can be adjusted step by step.

[0046] Further, in a case where the number of protrusions is one, the protrusion preferably has a smaller dimension in the axial direction of the opening portion 71 than the pressed portion 75. The dimension of the protrusion refers to, for example, the length from the boundary between the pressed portion 75 and the tapered portion 76b to the boundary between the pressed portion 75 and the wall portion 76a at the protrusion 76. By this, the contact surface pressure of the gear housing 70 and the sheath 80 can be reliably made high by the protrusion, and thus the sealing property between the gear housing 70 and the sheath 80 can be reliably improved. However, if the protrusion is of a structure in which the length in the axial direction of the opening portion 71 becomes smaller as it is farther from the pressed portion 75 in the radial direction, as in the protrusion 76, the protrusion can have the same dimension as the pressed portion 75 in the axial direction of the opening portion 71.

[0047] <Modification Example 3>

[0048] In the above embodiment, as the protrusions, the protrusions 76 of which the cross section along the axial direction of the opening portion 71 is trapezoidal are provided. However, the shape of the protrusions is not limited to the above. For example, the cross section of the protrusion along the axial direction of the opening portion 71 can be formed so as to be triangular, quadrangular, or semicircular. Further, in a case where the protrusions are plural, protrusions of different shapes in which the cross section along the axial direction of the opening portion 71 is different can be mixed, and protrusions in which the protrusion amount in the radial direction of the opening portion 71 is different can be mixed.

[0049] The structure, operation, and effects of the embodiment of the application configured as described above are summarized.

[0050] The electric power steering device 100 as a steering device has a rack shaft 30 for steering a wheel 1, a gear housing 70 as a housing that houses the rack shaft 30 and has an opening portion 71 through which the rack shaft 30 protrudes, a boot 80 that covers the opening portion 71 of the gear housing 70, and a boot band 90 as a ring-shaped band portion that presses and fixes the boot 80 toward an outer peripheral surface 72 of the gear housing 70, the gear housing 70 having a pressed portion 75 pressed by the boot band 90 among the outer peripheral surface 72 and ring-shaped protruding portions 76, 77, 78, 79 protruding in a radial direction of the opening portion 71 from the pressed portion 75.

[0051] Further, the protruding portions 76, 77, 78, 79 have smaller dimensions in the axial direction of the opening portion 71 than the pressed portion 75.

[0052] In the above structure, the boot 80 is pressed toward the protruding portions 76, 77, 78, 79 of the gear housing 70, and therefore, a load from the boot band 90 is easily applied to the protruding portions 76, 77, 78, 79 of the boot 80 compared to other portions of the pressed portion 75. Thus, the contact surface pressure of the gear housing 70 and the boot 80 is high at the protruding portions 76, 77, 78, 79. By this, the protruding portions 76, 77, 78, 79 of the gear housing 70 and the boot 80 can be made to be in close contact.

[0053] Further, the protruding portions 76, 77, 78, 79 have wall portions 76a, 77a, 78a, 79a that extend perpendicularly with respect to the axial direction from the pressed portion 75, and tapered portions 76b, 77b, 78b, 79b that extend toward the wall portions 76a, 77a, 78a, 79a from the pressed portion 75, the tapered portions 76b, 77b, 78b, 79b being provided on the opening portion 71 side of the gear housing 70 compared to the wall portions 76a, 77a, 78a, 79a.

[0054] In this structure, the tapered portions 76b, 77b, 78b, 79b that extend toward the wall portions 76a, 77a, 78a, 79a are provided on the opening portion 71 side of the gear housing 70 compared to the wall portions 76a, 77a, 78a, 79a, and therefore, the installation of the boot 80 to the gear housing 70 is not hindered by the protruding portions 76, 77, 78, 79. Further, since the installed boot 80 is caught by the wall portions 76a, 77a, 78a, 79a, the boot 80 is prevented from coming off the gear housing 70.

[0055] Further, the electric power steering apparatus 100 has, as the protrusions, a protrusion 77 as a first protrusion and protrusions 78, 79 as second protrusions that are provided further from the center of the pressed portion 75 in the axial direction than the protrusion 77, the protrusions 78, 79 having a larger protrusion amount in the radial direction than the protrusion amount of the protrusion 77 in the radial direction.

[0056] Since, in this structure, the protrusion amount in the radial direction of the protrusions 78, 79 on the side closer to the end portion side of the pressed portion 75 than the protrusion 77 on the central side of the pressed portion 75 is larger than the protrusion amount in the radial direction of the protrusion 77, the contact surface pressure of the gear housing 70 against the sheath 80 is high on the end portion side of the pressed portion 75. Here, the wall thickness of the sheath 80 is easily thin on the end portion side of the pressed portion 75. Thus, since the contact surface pressure of the gear housing 70 against the sheath 80 is high at the portion where the sheath 80 is easily thin, the sealing property between the gear housing 70 and the sheath 80 can be effectively improved.

[0057] The above describes the embodiments of the present application, but the above-described embodiments merely represent a part of application examples of the present application, and are not intended to limit the technical scope of the present application to the specific structures of the above-described embodiments.

[0058] This application claims priority based on Japanese Patent Application No. 2021-1064 filed on January 6, 2021 with the Japan Patent Office, and incorporates the entire contents of the application by reference in the present specification.

Claims

1. A steering device comprising: Rack and pinion shafts are used to change the direction of wheels; A housing that houses the rack shaft and has an opening for the rack shaft to protrude; A sheath that covers the opening of the outer casing; The annular band presses and secures the sheath towards the outer peripheral surface of the housing. The outer casing has a recess formed on the outer peripheral surface, a pressed portion in the recess that is pressed by the band portion, and an annular protrusion formed in the recess and protruding radially from the pressed portion into the opening. The strap and the sheath are installed together in the recess. The protrusion has: A wall portion that extends axially relative to the opening from the pressed portion; A tapered portion that extends from the pressed portion toward the wall portion. The tapered portion is positioned closer to the opening side of the outer casing than the wall portion.

2. The steering device as claimed in claim 1, wherein, The protrusion has a smaller dimension in the axial direction of the opening compared to the pressed portion.

3. The steering device as claimed in claim 1, wherein, The protrusion has a first protrusion and a second protrusion, wherein the second protrusion is positioned further away from the center of the pressed portion in the axial direction than the first protrusion. The amount of the second protrusion in the radial direction is greater than the amount of the first protrusion in the radial direction.

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