Steering system

Abstract

To suppress the decrease in torque sensor output stability after releasing the steering lock, which is caused by runout of the steering shaft while the steering lock is engaged. [Solution] The system comprises an upper shaft 83, a lower shaft 84 fitted to the upper shaft 83, an output shaft 85 connected to the lower shaft 84 via a torsion bar 86, an upper column 20 supporting the upper shaft 83, a lower column 30 that can move relative to the upper column 20, a torque sensor 40 that detects changes in relative rotation between the lower shaft 84 and the output shaft 85, a key lock collar 51 fitted to the lower shaft 84, and a metal runout prevention member 60 attached to the inner circumferential surface of the lower column 30 at a position between the key lock collar 51 and the torque sensor 40 in the axial direction, which restricts the radial movement of the lower shaft 84 by contacting a member arranged on the lower shaft 84 from the radial outside.

Description

Technical Field

[0001] The present disclosure relates to a steering device.

Background Art

[0002] Many steering devices mounted on vehicles include a lock mechanism that restricts the rotation of the steering shaft when not in use. The lock mechanism can restrict the rotation of the steering shaft by engaging a lock pin disposed on the housing side of the steering shaft with a groove formed in a collar that has a cylindrical shape and is disposed on the steering shaft. In a steering device having such a lock mechanism, when a large load in the direction of rotating the steering wheel is input while the steering shaft is locked by the lock mechanism, the steering shaft may deflect in the radial direction, which may affect the output of a torque sensor included in the steering device.

[0003] For this reason, some conventional steering devices suppress the deflection of the steering shaft and the runout of the steering shaft when a large load in the direction of rotating the steering wheel is received while the steering is locked. For example, in the vehicle steering device described in Patent Document 1, a synthetic resin deflection restricting member that restricts the radial movement of a cylindrical member attached to the steering shaft is interposed between the outer periphery of the cylindrical member and the inner periphery of a column tube of a steering column. Thereby, in Patent Document 1, the deflection restricting member restricts the deflection of the steering shaft with respect to the steering column via the cylindrical member, thereby suppressing the runout of the steering shaft.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

[0005] Here, if a very large load is applied in the direction that rotates the steering wheel while the steering is locked by the locking mechanism, a large radial load acts on the steering shaft, and a large load acts in the direction that causes the steering shaft to flex. However, if the runout of the steering shaft is suppressed by placing a flexure-restricting member made of synthetic resin between the cylindrical member attached to the steering shaft and the steering column, there is a possibility that the flexure-restricting member made of synthetic resin may deform when a large radial load is applied to the steering shaft.

[0006] In this case, the deflection-regulating member will not be able to completely suppress the deflection of the steering shaft, causing the steering shaft to deflect and potentially failing to suppress steering shaft runout. Since steering shaft runout affects the output of the torque sensor, if runout occurs in the steering shaft due to the load acting during steering lock, the output stability of the torque sensor is likely to decrease. For this reason, conventional steering systems had room for improvement in terms of the output stability of the torque sensor after the steering lock is released, which is caused by steering shaft runout during steering lock.

[0007] This disclosure has been made in view of the above, and aims to provide a steering device that can suppress the decrease in output stability of the torque sensor after the steering lock is released, which is caused by runout of the steering shaft while the steering lock is engaged. [Means for solving the problem]

[0008] The steering device of this disclosure includes an upper shaft extending in the axial direction of a central axis and having one end in the axial direction connected to a steering wheel; a lower shaft located on the other axial side of the upper shaft and fitted to the upper shaft, and capable of relative movement in the axial direction with respect to the upper shaft; an output shaft connected to the lower shaft via a torsion bar; a cylindrical upper column positioned on the outer circumference of the upper shaft and rotatably supporting the upper shaft; and a shaft positioned on the outer circumference of the lower shaft and fitted to the upper column, and the The system comprises a cylindrical lower column that is movable relative to the upper column in the axial direction; a torque sensor attached to the lower shaft and the output shaft for detecting changes in the relative rotation between the lower shaft and the output shaft; an annular key lock collar fitted to the outer circumferential surface of the lower shaft; and a metal runout prevention member attached to the inner circumferential surface of the lower column at a position between the key lock collar and the torque sensor in the axial direction, which restricts the radial movement of the lower shaft by contacting the lower shaft or a member arranged on the lower shaft from the radial outside.

[0009] With this configuration, when a large rotational force is applied to the steering shaft while the steering is locked, causing the lower shaft to move radially, the anti-vibration member can suppress the radial movement of the lower shaft. This prevents misalignment between the axis of the lower shaft and the output shaft, thereby suppressing steering shaft runout. Furthermore, if the anti-vibration member is made of an elastic material such as resin, when a large radial force is applied to the lower shaft, the anti-vibration member will elastically deform, making it difficult to suppress the radial movement of the lower shaft and thus difficult to suppress steering shaft runout. However, in the steering device disclosed herein, the anti-vibration member is made of metal. As a result, the anti-vibration member has rigidity, so when a large radial force is applied to the lower shaft, the anti-vibration member does not elastically deform, suppressing the radial movement of the lower shaft and thus suppressing steering shaft runout. Therefore, after a large radial force is removed from the steering shaft, the lower shaft and the output shaft extend coaxially. As a result, the torque sensor, which is attached to the lower shaft and the output shaft and detects the change in relative rotation between the lower shaft and the output shaft, can output a stable value. This suppresses the decrease in output stability of the torque sensor after the steering lock is released, which is caused by runout of the steering shaft while the steering lock is engaged.

[0010] In a preferred configuration, the runout prevention member is attached to the inner circumferential surface of the lower column and has a first portion extending in the axial direction, a second portion extending inward from the other axial side of the first portion, and a third portion extending toward one side in the axial direction from the inner side of the second portion, with the upper column positioned between the first portion and the third portion in the radial direction of the central axis.

[0011] In this configuration, the anti-runout member has a first part, a second part, and a third part, and the upper column is located radially between the first part and the third part. Therefore, when the upper column moves axially due to an impact such as a vehicle collision, it is difficult for the upper column to come into contact with the anti-runout member. This ensures that the amount of movement of the upper column is secured when the upper column moves axially due to a large impact on the steering system. As a result, the amount of collision energy absorbed when the steering system is subjected to a large impact can be increased, making it easier to control the collision load.

[0012] In a desirable configuration, a metal, annular metal spacer is fitted onto the outer circumferential surface of the lower shaft, and the runout prevention member restricts the radial movement of the lower shaft by contacting the outer circumferential surface of the metal spacer.

[0013] In this configuration, a metal spacer is fitted onto the lower shaft, and the runout prevention member restricts the radial movement of the lower shaft by contacting the outer surface of the metal spacer, thereby improving the ease of assembling the lower column to the lower shaft. In other words, by placing a metal spacer on the lower shaft that the runout prevention member contacts, the inner diameter of the runout prevention member can be increased. This allows the lower shaft to be passed through the inside of the lower column during the assembly process of the steering system, while the magnet of the torque sensor attached to the lower shaft is also passed through the inside of the runout prevention member. Therefore, when passing the lower shaft with the torque sensor magnet attached through the inside of the lower column, the runout prevention member can be attached to the inner surface of the lower column while the lower shaft is passed through the inside of the lower column. As a result, the ease of assembling the steering system can be improved, and manufacturing costs can be reduced.

[0014] In a desirable configuration, the runout prevention member is provided with a dust seal that slides against the outer circumferential surface of the metal spacer.

[0015] In this configuration, a dust seal is placed in the runout prevention member that slides against the outer surface of the metal spacer. This prevents dust and water that have entered the inside of the upper and lower columns from approaching the torque sensor. As a result, false readings by the torque sensor caused by dust and water adhering to the torque sensor can be suppressed. Consequently, a decrease in the output stability of the torque sensor can be suppressed.

[0016] In a desirable configuration, the runout prevention member is a sealed bearing.

[0017] With this configuration, by arranging a sealed bearing as a vibration damping member, even when a large radial force acts on the lower shaft while the steering lock is engaged, the radial movement of the lower shaft can be suppressed by the sealed bearing. As a result, vibration of the steering shaft can be suppressed, and the torque sensor can stably output the detected steering torque value. Consequently, the decrease in the output stability of the torque sensor after the steering lock is released, which is caused by vibration of the steering shaft while the steering lock is engaged, can be suppressed.

[0018] In a preferred configuration, the key lock collar has an extension whose position in the axial direction includes the position in the axial direction where the runout prevention member is positioned, and the runout prevention member restricts the radial movement of the lower shaft by contacting the outer circumferential surface of the extension of the key lock collar.

[0019] According to this configuration, the key lock color has an extension portion, and the anti-vibration member restricts the radial movement of the lower shaft by abutting against the extension portion. Therefore, even when a large radial force acts on the lower shaft during steering lock, the radial movement of the lower shaft can be suppressed. As a result, the vibration of the steering shaft can be suppressed, and it is possible to suppress the radial gap between the magnet and the stator of the torque sensor from varying in size depending on the position in the circumferential direction due to the vibration between the lower shaft and the output shaft. Therefore, the torque sensor can stably output the detected output value of the steering torque. As a result, it is possible to suppress a decrease in the output stability of the torque sensor after the steering lock is released due to the vibration of the steering shaft during the steering lock.

Effects of the Invention

[0020] The steering device according to the present disclosure has an effect that it is possible to suppress a decrease in the output stability of the torque sensor after the steering lock is released due to the vibration of the steering shaft during the steering lock.

Brief Description of the Drawings

[0021] [Figure 1] FIG. 1 is a schematic diagram of a steering device according to the first embodiment. [Figure 2] FIG. 2 is a cross-sectional view of a main part of a steering column according to the first embodiment. [Figure 3] FIG. 3 is a detailed view around the anti-vibration member shown in FIG. 2. [Figure 4] FIG. 4 is a cross-sectional view taken along line A-A of FIG. 3. [Figure 5] FIG. 5 is an explanatory diagram showing the relationship between the anti-vibration member and the upper column when the upper column moves to the side where the anti-vibration member is located. [Figure 6] FIG. 6 is a cross-sectional view of a main part of a steering column included in a steering device according to the second embodiment. [Figure 7]FIG. 7 is a cross-sectional view of a main part of a steering column included in the steering apparatus according to the third embodiment.

Embodiments for Carrying Out the Invention

[0022] Hereinafter, the present disclosure will be described in detail with reference to the drawings. Note that the present disclosure is not limited by the following embodiments for carrying out the invention (hereinafter referred to as embodiments). In addition, the constituent elements in the following embodiments include those that can be easily assumed by those skilled in the art, substantially the same ones, and those within a so-called equivalent range. Furthermore, the constituent elements disclosed in the following embodiments can be combined as appropriate.

[0023] [First Embodiment] FIG. 1 is a schematic diagram of a steering apparatus 80 according to the first embodiment. As shown in FIG. 1, the steering apparatus 80 includes, in the order in which the force given by an operator is transmitted, a steering wheel 81, a steering column 1, an electric motor 111, a reduction gear device 112, a universal joint 101, an intermediate shaft 102, a universal joint 103, and is joined to a pinion shaft 104. In the following description, the direction along the central axis AX of the steering shaft 82 is referred to as the "axial direction", and the direction intersecting (orthogonal) to the axial direction is referred to as the "radial direction". Also, in the following description, the upper side in the normal use state of the vehicle on which the steering apparatus 80 is mounted is also described as the upper side in the steering apparatus 80, the lower side in the normal use state of the vehicle is also described as the lower side in the steering apparatus 80, and the horizontal direction in the normal use state of the vehicle is also described as the horizontal direction in the steering apparatus 80.

[0024] The steering column 1 is provided with a steering shaft 82 and a torque sensor 40. The steering shaft 82 includes an upper shaft 83, a lower shaft 84 (see FIG. 2), an output shaft 85, and a torsion bar 86 (see FIG. 2). The steering column 1 will be described in detail later.

[0025] The intermediate shaft 102 connects the universal joint 101 and the universal joint 103. One end of the intermediate shaft 102 is connected to the universal joint 101, and the other end is connected to the universal joint 103. One end of the pinion shaft 104 is connected to the universal joint 103, and the other end is connected to the steering gear 105. The universal joints 101 and 103 are, for example, cardan joints. The rotation of the steering shaft 82 is transmitted to the pinion shaft 104 via the intermediate shaft 102. Therefore, the intermediate shaft 102 is rotatable together with the steering shaft 82.

[0026] The steering gear 105 comprises a pinion gear 105a and a rack bar 105b. The pinion gear 105a is connected to the pinion shaft 104. The rack bar 105b meshes with the pinion gear 105a. The steering gear 105 converts the rotational motion transmitted to the pinion gear 105a into linear motion using the rack bar 105b. The rack bar 105b is connected to the tie rod 106. The movement of the rack bar 105b changes the angle of the wheels. In other words, the steering device 80 is a rack and pinion type electric power steering device.

[0027] The steering device 80 further comprises an ECU (Electronic Control Unit) 110 and a vehicle speed sensor 115. The electric motor 111, vehicle speed sensor 115, and torque sensor 40 are electrically connected to the ECU 110. The reduction gear 112 is attached to the electric motor 111. The torque sensor 40 outputs the steering torque transmitted to the steering shaft 82 to the ECU 110 via CAN (Controller Area Network) communication. The vehicle speed sensor 115 detects the driving speed (vehicle speed) of the vehicle on which the steering device 80 is mounted. The vehicle speed sensor 115 is mounted on the vehicle body and outputs the vehicle speed to the ECU 110 via CAN communication.

[0028] The ECU 110 controls the operation of the electric motor 111. The ECU 110 acquires signals from the torque sensor 40 and the vehicle speed sensor 115. When the ignition switch 116 is ON, the ECU 110 is supplied with power from the power supply unit 117 (e.g., the vehicle's battery). The ECU 110 calculates an auxiliary steering command value based on the steering torque and vehicle speed. The ECU 110 adjusts the power value supplied to the electric motor 111 based on the auxiliary steering command value. The ECU 110 acquires information on the induced voltage of the electric motor 111 or information output from a resolver or the like provided on the electric motor 111. By controlling the electric motor 111, the force required to operate the steering wheel 81 is reduced.

[0029] Next, the steering column 1 will be described. Figure 2 is a cross-sectional view of the main part of the steering column 1 according to the first embodiment. In the following description, one side of the central axis AX of the steering shaft 82 in the axial direction will be referred to as the X1 side, and the other side in the axial direction will be referred to as the X2 side.

[0030] The steering column 1 comprises a housing 10, a steering shaft 82, and a torque sensor 40. The steering shaft 82 is connected to a steering wheel 81 (see Figure 1) at its X1 end in the axial direction, and is rotatable by the torque input from the steering wheel 81. The steering shaft 82 has an upper shaft 83, a lower shaft 84, an output shaft 85, and a torsion bar 86. The upper shaft 83, lower shaft 84, output shaft 85, and torsion bar 86 are arranged coaxially with their central axes AX coinciding. That is, the upper shaft 83, lower shaft 84, output shaft 85, and torsion bar 86 extend in the axial direction of the central axis AX of the steering shaft 82.

[0031] In a plan view of the vehicle, the steering column 1 is mounted in the vehicle such that the axial direction of the steering shaft 82 is aligned with the longitudinal direction of the vehicle, the X1 side to which the steering wheel 81 is connected is the rear side in the longitudinal direction of the vehicle, and the steering shaft 82 extends forward from the steering wheel 81. In other words, the steering column 1 is mounted in the vehicle such that the X1 side in the axial direction is the rear side in the longitudinal direction of the vehicle, and the X2 side is the front side in the longitudinal direction of the vehicle.

[0032] The upper shaft 83 is a cylindrical shaft with a hollow section. In the first embodiment, the upper shaft 83 is formed in a substantially cylindrical shape that is hollow overall, with a diameter that varies depending on the position in the axial direction. The steering wheel 81 (see Figure 1), which is connected to the steering shaft 82, is connected to one end of the upper shaft 83 in the axial direction. That is, the end of the upper shaft 83 on the X1 side in the axial direction is connected to the steering wheel 81.

[0033] The lower shaft 84 is positioned on the X2 side in the axial direction relative to the upper shaft 83. The portion of the lower shaft 84 closer to the upper shaft 83 in the axial direction is inserted inside the upper shaft 83 and connected to the upper shaft 83. The upper shaft 83 and the lower shaft 84 are combined such that relative movement in the axial direction is possible, but relative rotation is not possible, by contact between a portion of the inner circumferential surface 83c of the upper shaft 83 and a portion of the outer circumferential surface 84b of the lower shaft 84. In the first embodiment, the upper shaft 83 and the lower shaft 84 are combined such that relative movement in the axial direction is possible, but relative rotation is not possible, by spline engagement of the outer circumferential surface 84b of the portion of the lower shaft 84 that is inserted inside the upper shaft 83 and the inner circumferential surface 83c of the upper shaft 83. That is, the upper shaft 83 and the lower shaft 84, which are combined in a way that prevents relative rotation, can expand and contract in the axial direction.

[0034] The output shaft 85 is located on the X2 side of the lower shaft 84, that is, on the opposite side of the lower shaft 84 from the side connected to the upper shaft 83. The lower shaft 84 and the output shaft 85 are connected via a torsion bar 86. The torsion bar 86 is a solid elastic member that extends in the axial direction, and holes are formed in the lower shaft 84 and the output shaft 85 into which the torsion bar 86 fits. The X1 end of the torsion bar 86 is inserted into the lower shaft 84 and fixed thereto, and the X2 end is inserted into the output shaft 85 and fixed thereto. In the first embodiment, the torsion bar 86 is fixed to the lower shaft 84 by press-fitting into a hole formed in the lower shaft 84, and to the output shaft 85 by a connecting pin 87 that passes radially through both the output shaft 85 and the torsion bar 86. As a result, the lower shaft 84 and the output shaft 85 are connected via a torsion bar 86.

[0035] The housing 10 positions the steering shaft 82 inside and supports the steering shaft 82 so that it can rotate freely. The housing 10 includes an upper column 20, a lower column 30, and a gear housing 35. The upper column 20 and the lower column 30 are each cylindrical members, and the steering shaft 82 is positioned inside the cylindrical upper column 20 and lower column 30. The gear housing 35 is the housing 10 for the reduction gear 112.

[0036] The upper column 20 is positioned on the X1 side in the axial direction relative to the lower column 30. In other words, the upper column 20 is positioned on the side of the lower column 30 where the upper shaft 83 is positioned relative to the lower shaft 84 in the axial direction. Therefore, the upper column 20 is positioned on the outer circumference side of the upper shaft 83. The upper shaft 83, which is positioned inside the upper column 20, has its axial end on the X1 side exposed from the inside of the upper column 20. The steering wheel 81 (see Figure 1) is connected to the X1 side end of the upper shaft 83 that is exposed from the inside of the upper column 20 in this manner.

[0037] A bearing 25 is positioned inside the upper column 20, near the end where the upper shaft 83 is exposed in the axial direction. The bearing 25 is positioned between the inner circumferential surface of the upper column 20 and the outer circumferential surface of the upper shaft 83. In this way, the upper column 20 rotatably supports the upper shaft 83 via the bearing 25.

[0038] The lower column 30 is positioned on the X2 side in the axial direction relative to the upper column 20. In other words, the lower column 30 is positioned on the side of the upper column 20 where the lower shaft 84 is positioned relative to the upper shaft 83 in the axial direction. Therefore, the lower column 30 is positioned on the outer circumference side of the lower shaft 84. The lower column 30 covers the portion of the upper column 20 near the end opposite to the end where the upper shaft 83 is exposed in the axial direction, and is fitted into the upper column 20. That is, the portion of the upper column 20 near the end opposite to the end where the upper shaft 83 is exposed in the axial direction is inserted inside the lower column 30.

[0039] The upper column 20 and the lower column 30 are capable of relative movement in the axial direction. In other words, the upper column 20, which is partially inserted inside the lower column 30, is capable of relative movement in the axial direction with respect to the lower column 30. As a result, the housing 10 of the steering column 1 can expand and contract in the axial direction as the upper column 20 and the lower column 30 move relative to each other in the axial direction. Consequently, when the upper shaft 83 and the lower shaft 84 expand and contract in the axial direction, the upper column 20 and the lower column 30 can also expand and contract in the axial direction in accordance with the expansion and contraction of the upper shaft 83 and the lower shaft 84.

[0040] In other words, the upper shaft 83 and the lower shaft 84 are capable of relative movement in the axial direction, and both the upper column 20 and the lower column 30 are capable of relative movement in the axial direction. On the other hand, the lower shaft 84 is positioned so as not to be able to move relative to the lower column 30 in the axial direction, and the upper shaft 83 is positioned so as not to be able to move relative to the upper column 20 in the axial direction. For these reasons, when the upper shaft 83 expands and contracts in the axial direction relative to the lower shaft 84, the upper column 20 also expands and contracts in the axial direction relative to the lower column 30 in accordance with the expansion and contraction of the upper shaft 83 relative to the lower shaft 84.

[0041] The gear housing 35 is positioned axially on the X2 side relative to the lower column 30, that is, on the opposite side in the axial direction from the side where the upper column 20 is located relative to the lower column 30, and is attached to the lower column 30 by mounting bolts 36. For this reason, the gear housing 35 mainly covers the output shaft 85 of the steering shaft 82. Inside the gear housing 35 is the worm wheel 114 of the reduction gear 112. The reduction gear 112 consists of a worm (not shown) and a worm wheel 114 that meshes with the worm, and the worm is attached directly or indirectly to the drive shaft of the electric motor 111 (see Figure 1). The worm wheel 114 is attached to the output shaft 85 of the steering shaft 82 by press-fitting it onto the output shaft 85.

[0042] Therefore, the driving force generated by the electric motor 111 is transmitted to the worm wheel 114 via the worm, and then to the output shaft 85. At this time, the worm and worm wheel 114 reduce the rotational speed of the driving force generated by the electric motor 111 and increase the torque. The reduction gear 112 is thus capable of transmitting the driving force generated by the electric motor 111 to the output shaft 85 with increased torque, and providing auxiliary steering torque to the output shaft 85. In other words, the steering device 80 according to the first embodiment is a column-assist type electric power steering device in which auxiliary steering torque is applied to the steering shaft 82.

[0043] Two bearings 55 and 56 are positioned on either side of the worm wheel 114 in the axial direction, and the output shaft 85 is supported by these two bearings 55 and 56. One bearing 55 is positioned on the X1 side in the axial direction relative to the worm wheel 114 and is located between the lower column 30 and the output shaft 85. The other bearing 56 is positioned on the X2 side in the axial direction relative to the worm wheel 114 and is located between the gear housing 35 and the output shaft 85. Thus, the output shaft 85 is rotatably supported relative to the lower column 30 and the gear housing 35 via the two bearings 55 and 56. That is, the steering shaft 82 is rotatably supported relative to the housing 10 by a bearing 25 positioned between it and the upper column 20, a bearing 55 positioned between it and the lower column 30, and a bearing 56 positioned between it and the gear housing 35.

[0044] As described above, the housing 10, which rotatably supports the steering shaft 82, is mounted to the vehicle so as to be rotatable together with the steering shaft 82, with the pivot axis R extending in the vehicle width direction as its center. More specifically, the gear housing 35 is provided with a pivot bracket 37, and the pivot bracket 37 has an insertion hole 37a that opens in the vehicle width direction. A pivot bolt (not shown) is passed through the insertion hole 37a of the pivot bracket 37, and the pivot bolt is screwed into a fixing member (not shown) on the vehicle body side. As a result, the housing 10 can rotate relative to the vehicle with respect to the pivot bolt that passes through the insertion hole 37a of the pivot bracket 37, and is mounted to the vehicle so as to be rotatable. In other words, the housing 10 is mounted to the vehicle so as to be rotatable around the pivot axis R, which extends in the vehicle width direction, with the axis of the pivot bolt extending in the vehicle width direction or the axis of the insertion hole 37a of the pivot bracket 37 as its center.

[0045] The torque sensor 40 is located inside the housing 10 and is a sensor device that detects physical quantities associated with the rotation of the steering shaft 82. The torque sensor 40 is attached to the lower shaft 84 and the output shaft 85, and is capable of detecting changes in the relative rotation between the lower shaft 84 and the output shaft 85 as a physical quantity associated with the rotation of the steering shaft 82.

[0046] More specifically, the torque sensor 40 includes a magnet 41 and a stator 42. The magnet 41 and stator 42 are located inside the housing 10 near where the lower shaft 84 and the output shaft 85 are connected, and are positioned on the X1 side in the axial direction from the bearing 55 that rotatably supports the output shaft 85. The magnet 41 is formed in an annular shape and is fixed to the lower shaft 84. The stator 42 has a portion that is in the same axial position as the magnet 41, and is positioned radially outside the magnet 41 and fixed to the output shaft 85.

[0047] When the stator 42 is positioned outside the magnet 41 in the radial direction, it is positioned with a radial gap between it and the magnet 41. Therefore, when the lower shaft 84 and the output shaft 85 rotate relative to each other, the magnet 41 and the stator 42 can also rotate relative to each other in accordance with the relative rotation of the lower shaft 84 and the output shaft 85.

[0048] Furthermore, the torque sensor 40 includes a magnetic collection yoke (not shown) and a Hall IC (not shown), both of which are attached to the lower column 30. The magnetic collection yoke is a component for detecting changes in magnetic flux acting from the magnet 41 to the stator 42, and is positioned near the stator 42. The Hall IC detects changes in magnetic flux density acting on the magnetic collection yoke and is capable of converting the detected change in magnetic flux density into an electrical signal and outputting it as an electrical signal. Since the magnetic flux density detected by the Hall IC changes according to the magnitude of the steering torque, the torque sensor 40 transmits the magnitude of the detected steering torque to the ECU 110 by outputting the electrical signal converted from the change in magnetic flux density to the ECU 110.

[0049] Furthermore, a key lock collar 51, which is part of a locking device 50 that restricts the rotation of the steering shaft 82, is attached to the steering shaft 82. The key lock collar 51 is formed in an annular shape and is positioned near the location where the torque sensor 40 is located on the lower shaft 84, at a position on the X1 side in the axial direction relative to the torque sensor 40. The key lock collar 51 is made of metal and is fitted to the outer circumferential surface of the lower shaft 84, so that it cannot rotate relative to the lower shaft 84. The locking device 50 will be described later.

[0050] In the first embodiment, a runout prevention member 60 is positioned between the key lock collar 51 and the torque sensor 40 in the axial direction. The runout prevention member 60 is attached to the inner circumferential surface of the lower column 30 by press-fitting it into the inside of the lower column 30.

[0051] Figure 3 is a detailed view of the area around the runout prevention member 60 shown in Figure 2. The runout prevention member 60 is made of metal such as iron or aluminum, and by contacting the lower shaft 84 or a member placed on the lower shaft 84 from the radial outside, it is possible to restrict the radial movement of the lower shaft 84. In the first embodiment, a metal spacer 70 is fitted in the same position in the axial direction as the position where the runout prevention member 60 is placed in the axial direction, and the runout prevention member 60 can restrict the radial movement of the lower shaft 84 by contacting the outer circumferential surface of the metal spacer 70. The metal spacer 70 is made of metal, similar to the runout prevention member 60, and has an annular or sleeve-shaped form with an inner diameter approximately the same as the outer diameter at the position where the metal spacer 70 is placed on the lower shaft 84, and is press-fitted into the lower shaft 84.

[0052] The runout prevention member 60, which is positioned on the inner circumferential surface of the lower column 30, has a first portion 61, a second portion 62, and a third portion 63, and the runout prevention member 60 is formed by integrally forming the first portion 61, the second portion 62, and the third portion 63. The runout prevention member 60 having the first portion 61, the second portion 62, and the third portion 63 is formed in a substantially U-shape in a cross-section including the central axis AX, with the X2 side closed and the X1 side open.

[0053] More specifically, the first part 61 is formed in an annular shape, and its outer diameter is approximately the same as the inner diameter of the position on the inner surface of the lower column 30 where the runout prevention member 60 is positioned. The annular shape of the first part 61 has an axial length shorter than the axial length of the metal spacer 70; for example, its axial length is approximately half the axial length of the metal spacer 70. The first part 61 is attached to the inner surface of the lower column 30 by press-fitting it into the inner surface of the lower column 30. In other words, the first part 61 is the part of the runout prevention member 60 that attaches the runout prevention member 60 to the inner surface of the lower column 30.

[0054] The second portion 62 is formed in an annular shape and extends inward from the portion on the axial X2 side of the first portion 61. That is, the annular second portion 62 is located at the axial X2 end of the first portion 61 and extends radially inward from the X2 end of the first portion 61. The second portion 62 is the closed portion on the X2 side of the U-shape, which is the shape of the runout prevention member 60 in a cross-section including the central axis AX.

[0055] The third portion 63 is formed in an annular shape and extends from the inner circumference of the second portion 62 toward the axial X1 side. That is, the annular shape of the third portion 63 extends from the radial inner end of the second portion 62 toward the axial X1 side. The axial length of the third portion 63 extending from the second portion 62 is approximately the same as the axial length of the first portion 61. Also, the outer diameter of the third portion 63 is smaller than the inner diameter of the first portion 61. Therefore, the first portion 61 and the third portion 63 extend parallel to each other toward the axial X1 side, with the first portion 61 extending from the outer circumference of the second portion 62 and the third portion 63 extending from the inner circumference of the second portion 62, with approximately the same axial length.

[0056] Furthermore, the inner diameter of the third portion 63 is larger than the outer diameter of the metal spacer 70. Therefore, when the runout prevention member 60 is attached to the inner circumferential surface of the lower column 30, there is a radial gap between the inner circumferential surface of the third portion 63 of the runout prevention member 60 and the outer circumferential surface of the metal spacer 70, which is attached to the outer circumferential surface of the lower shaft 84. The radial gap between the inner circumferential surface of the third portion 63 of the runout prevention member 60 and the outer circumferential surface of the metal spacer 70 is smaller than the radial gap between the magnet 41 of the torque sensor 40 and the stator 42.

[0057] Furthermore, the outer diameter of the metal spacer 70 is approximately the same as the outer diameter of the magnet 41 of the torque sensor 40, and therefore the outer diameter of the third portion 63 of the runout prevention member 60 is larger than the outer diameter of the magnet 41 of the torque sensor 40. As a result, when the lower shaft 84 to which the magnet 41 is attached is passed through the inside of the lower column 30 during the assembly process of the steering column 1, the runout prevention member 60 can be attached to the inner surface of the lower column 30, and the lower shaft 84 can be passed through the inside of the lower column 30. In other words, when the lower shaft 84 is passed through the inside of the lower column 30, the magnet 41 to which the lower shaft 84 is attached can pass through the inside of the runout prevention member 60, so the lower shaft 84 can be passed through the inside of the lower column 30 with the runout prevention member 60 attached to the inner surface.

[0058] As described above, the runout prevention member 60, which has a U-shaped cross-section due to having a first portion 61, a second portion 62, and a third portion 63, is formed to a size that allows the upper column 20 (see Figure 2) to fit into the inner part of the U-shape (see Figure 5). In other words, the distance D2 between the central axis AX and the inner surface of the first portion 61 of the runout prevention member 60 is greater than the distance D1 (see Figure 2) between the central axis AX and the outer surface of the upper column 20. Also, the distance D4 between the central axis AX and the outer surface of the third portion 63 of the runout prevention member 60 is smaller than the distance D3 (see Figure 2) between the central axis AX and the inner surface of the upper column 20. For this reason, the radial position of the upper column 20 is located between the first portion 61 and the third portion 63, and the upper column 20 can fit into the portion of the runout prevention member 60 between the first portion 61 and the third portion 63 in the radial direction.

[0059] Furthermore, a dust seal 65 is provided on the runout prevention member 60, which slides against the outer circumferential surface of the metal spacer 70. The dust seal 65 is formed in an annular shape and is located at the axial end on the X1 side of the third portion 63 of the runout prevention member 60. The dust seal 65 is made of rubber material and is attached to the axial end on the X1 side of the third portion 63 of the runout prevention member 60, for example, by vulcanization bonding.

[0060] The runout prevention member 60, when the dust seal 65 is attached to the third portion 63, has an axial length including the dust seal 65 that is approximately the same as the axial length of the metal spacer 70. Furthermore, the outer diameter of the dust seal 65 is substantially the same as the outer diameter of the third portion 63, and the inner diameter of the dust seal 65 is substantially the same for most of the inner diameter of the third portion 63. Therefore, when the dust seal 65 is attached to the third portion 63, it is positioned radially outside the metal spacer 70 attached to the lower shaft 84. That is, the dust seal 65 is positioned so that its inner circumferential surface faces the outer circumferential surface of the metal spacer 70.

[0061] Furthermore, the dust seal 65 has a convex portion 65a on a part of its inner circumferential surface that is radially convex inward. When no load is applied to the convex portion 65a on the inner circumferential surface of the dust seal 65, the inner diameter is smaller than the outer diameter of the metal spacer 70. Therefore, when the runout prevention member 60 is attached to the inner circumferential surface of the lower column 30 and the metal spacer 70 is attached to the lower shaft 84, the inner circumferential surface of the dust seal 65 faces the outer circumferential surface of the metal spacer 70, and the convex portion 65a of the dust seal 65 contacts the outer circumferential surface of the metal spacer 70 while undergoing elastic deformation. Consequently, when the lower shaft 84 rotates relative to the lower column 30, the convex portion 65a on the inner circumferential surface of the dust seal 65 slides against the outer circumferential surface of the metal spacer 70, which rotates integrally with the lower shaft 84.

[0062] Furthermore, a portion of the lower shaft 84 near the X2 end of the lower shaft 84 is recessed into the output shaft 85 near the X1 end of the output shaft 85. In other words, the portion of the lower shaft 84 near the X2 end of the lower shaft 84 is recessed into the output shaft 85 together with the torsion bar 86 near the X1 end of the output shaft 85. A bush 88 is positioned between the portion of the lower shaft 84 that is recessed into the output shaft 85 and the output shaft 85. The bush 88 is formed in an annular shape and is positioned between the outer circumferential surface of the portion of the lower shaft 84 that is recessed into the output shaft 85 and the inner circumferential surface of the portion of the output shaft 85 into which the lower shaft 84 is recessed, and is in contact with both the lower shaft 84 and the output shaft 85. With the bush 88 positioned between them in this way, radial play between the lower shaft 84 and the output shaft 85 is suppressed.

[0063] Next, the locking device 50 will be described. Figure 4 is a cross-sectional view of Figure 3, AA. The locking device 50 has a key lock collar 51 and a lock pin 54. The key lock collar 51 is formed in an annular shape and is fitted and fixed to the outer circumferential surface of the lower shaft 84. Multiple protrusions 52 are provided on the outer circumference of the key lock collar 51, projecting radially outward. Multiple protrusions 52 are arranged at equal intervals along the circumferential direction on the outer circumference of the key lock collar 51. Grooves 52a are provided between adjacent protrusions 52 in the circumferential direction of the key lock collar 51.

[0064] The lower column 30 is provided with a hole-shaped opening 31 that penetrates the lower column 30 radially. The opening 31 is formed in the lower column 30 at a position that includes the position where the key lock collar 51 is positioned in the axial direction. The lock pin 54 is positioned at the location of the opening 31 in the lower column 30 and is provided to be movable in the radial direction. The lock pin 54 is capable of passing radially through the opening 31 in the lower column 30.

[0065] The lock pin 54 moves radially inward and can be inserted into and fitted into the groove 52a between the protrusions 52 of the key lock collar 51. When the lock pin 54 is fitted into the groove 52a of the key lock collar 51, the lower column 30 and the lower shaft 84 cannot rotate relative to each other. Therefore, when the lock pin 54 is fitted into the groove 52a of the key lock collar 51, the steering wheel 81 (see Figure 1) cannot rotate, thus preventing theft of the vehicle.

[0066] Next, the operation of the steering device 80 will be explained. When the steering wheel 81 is operated while driving a vehicle equipped with the steering device 80, the steering force applied to the steering wheel 81 is transmitted from the steering wheel 81 to the steering shaft 82. The steering force transmitted to the steering shaft 82 is transmitted as steering torque from the steering shaft 82 to the intermediate shaft 102, and from the intermediate shaft 102 to the pinion gear 105a via the pinion shaft 104. As a result, the steering gear 105, which has the pinion gear 105a, converts the rotational motion transmitted from the pinion gear 105a into linear motion of the rack bar 105b, and operates the tie rod 106.

[0067] Furthermore, the steering device 80 according to the first embodiment has an electric motor 111 that generates auxiliary steering torque to assist the driver's steering. The electric motor 111 generates auxiliary steering torque based on the steering torque detected by a torque sensor 40 positioned between the lower shaft 84 and the output shaft 85 of the steering shaft 82.

[0068] The torque sensor 40 detects the steering torque applied from the steering wheel 81 to the steering shaft 82 based on the angle of relative rotation when the lower shaft 84 and the output shaft 85 rotate relative to each other. That is, since the lower shaft 84 and the output shaft 85 are connected via a torsion bar 86, when steering torque is applied to the lower shaft 84 via the upper shaft 83 to which the steering wheel 81 is attached, the steering torque is transmitted between the lower shaft 84 and the output shaft 85 via the torsion bar 86. At that time, the torsion bar 86 twists slightly, causing the lower shaft 84 and the output shaft 85 to rotate slightly relative to each other.

[0069] The torque sensor 40 has a magnet 41 attached to the lower shaft 84 and a stator 42 attached to the output shaft 85. Therefore, when the lower shaft 84 and the output shaft 85 rotate relative to each other, the magnet 41 and stator 42 of the torque sensor 40 also rotate relative to each other. The angle of relative rotation between the magnet 41 and the stator 42 increases as the steering torque acting between the lower shaft 84 and the output shaft 85 increases.

[0070] When the magnet 41 and the stator 42 rotate relative to each other, the magnetic flux acting from the magnet 41 to the stator 42 changes. The magnetic collecting yoke positioned near the stator 42 is capable of detecting this change in magnetic flux. Therefore, when the magnet 41 and the stator 42 rotate relative to each other due to the relative rotation of the lower shaft 84 and the output shaft 85, the magnetic collecting yoke positioned near the stator 42 can detect this change in magnetic flux.

[0071] Thus, the magnetic flux acting from the magnet 41 to the stator 42, as detected by the magnetic collecting yoke, changes according to the angle of relative rotation between the magnet 41 and the stator 42. The Hall IC in the torque sensor 40 detects the magnetic flux that changes according to the angle of relative rotation between the magnet 41 and the stator 42, as detected by the magnetic collecting yoke, using a Hall element, and converts it into an electrical signal in the output circuit, which is then transmitted to the ECU 110 as an output signal from the torque sensor 40. In other words, the torque sensor 40 detects the change in magnetic flux acting from the magnet 41 to the stator 42 using the magnetic collecting yoke and the Hall IC, thereby detecting the steering torque applied from the steering wheel 81 through the upper shaft 83 to the lower shaft 84, and transmits the detected steering torque as an electrical signal to the ECU 110.

[0072] The ECU 110 operates the electric motor 111 based on the electrical signal transmitted from the torque sensor 40, generating auxiliary steering torque in the electric motor 111. In other words, the electrical signal transmitted from the Hall IC of the torque sensor 40 to the ECU 110 changes according to the angle of relative rotation between the magnet 41 and the stator 42, and changes based on the steering torque acting between the lower shaft 84 and the output shaft 85. Therefore, the ECU 110 uses the electrical signal transmitted from the Hall IC of the torque sensor 40 as information that changes according to the steering torque acting on the lower shaft 84 and the output shaft 85, and adjusts the power value supplied to the electric motor 111 based on the electrical signal transmitted from the Hall IC, thereby generating auxiliary steering torque in the electric motor 111.

[0073] Specifically, the ECU 110 acquires a steering torque signal from the torque sensor 40, a vehicle speed signal from the vehicle speed sensor 115, and operational information of the electric motor 111 from a rotation detection device installed on the electric motor 111. Based on this operational information, the steering torque, and the vehicle speed signal, the ECU 110 generates auxiliary steering torque in the electric motor 111. The auxiliary steering torque generated by the electric motor 111 is transmitted to the output shaft 85 of the steering shaft 82 via a worm and worm wheel 114 attached to the drive shaft of the electric motor 111. As a result, the steering force applied by the driver to the steering wheel 81 is assisted by the auxiliary steering torque generated by the electric motor 111.

[0074] Furthermore, the steering column 1 of the steering device 80 is capable of adjusting the height and fore-aft position of the steering wheel 81. That is, the steering column 1 is capable of adjusting the tilt and telescopic position of the steering wheel 81. The height and fore-aft position of the steering wheel 81 can be adjusted electrically or manually. If the height and fore-aft position of the steering wheel 81 are adjusted electrically, an electric motor (not shown) is mounted on the steering column 1 to generate the driving force necessary to operate the steering column 1 when these positions are adjusted.

[0075] When adjusting the height of the steering wheel 81 attached to the steering shaft 82, the housing 10 and the steering shaft 82 are rotated together around a pivot axis R that extends in the vehicle width direction. As a result, the steering wheel 81 attached to one end of the steering shaft 82 also rotates around the pivot axis R, allowing the height of the steering wheel 81, i.e., its tilt position, to be adjusted. In other words, the tilt position can be adjusted by rotating the steering column 1 around the pivot axis R, thereby changing the inclination angle of the central axis of the steering shaft 82 relative to the horizontal direction when the steering column 1 is mounted on the vehicle, and thus adjusting the height of the steering wheel 81.

[0076] When adjusting the fore-aft position of the steering wheel 81 attached to the steering shaft 82, the upper shaft 83 to which the steering wheel 81 is attached is moved axially relative to the lower shaft 84. This allows the steering wheel 81 to be moved in the fore-aft direction together with the upper shaft 83, thereby adjusting the fore-aft position, i.e., the telescopic position, of the steering wheel 81.

[0077] Furthermore, when the upper shaft 83 is moved axially relative to the lower shaft 84 in this manner, the upper column 20 also moves axially relative to the lower column 30 along with the upper shaft 83. Since the upper shaft 83 is rotatably supported by the upper column 20 via the bearing 25, the upper column 20 moves axially along with the upper shaft 83, maintaining the state in which the upper shaft 83 is rotatably supported by the upper column 20. As a result, the steering column 1 can adjust the front-rear position of the steering wheel 81 while maintaining the state in which the steering shaft 82 is rotatably supported.

[0078] The steering column 1 rotatably supports the steering shaft 82 inside the housing 10 as described above, but the steering column 1 has a portion where the inner space and the outer space of the housing 10 are in communication. For example, the portion of the steering shaft 82 near the steering wheel 81 is rotatably supported by the upper column 20 via a bearing 25, so a small gap is formed in the portion where the bearing 25 is located, connecting the inner space and the outer space of the housing 10. In other words, since the bearing 25 is composed of an outer ring, an inner ring, and a plurality of rolling elements arranged between the outer ring and the inner ring, the portions between the rolling elements form a gap that connects the inner space and the outer space of the housing 10. Also, the opening 31 of the lower column 30 where the lock pin 54 of the locking device 50 is located is a hole that penetrates the lower column 30 radially.

[0079] Therefore, dust and water can enter the inside of the housing 10 through these gaps and holes. The magnet 41 and stator 42 of the torque sensor 40 are located inside the housing 10. If dust or water adheres to the torque sensor 40, the output may become unstable and prone to false detection, but a dust seal 65 is located at the X1 side of the torque sensor 40 in the axial direction. The dust seal 65 is located on the runout prevention member 60 attached to the lower column 30, and the protrusion 65a of the dust seal 65 slides against the metal spacer 70 that fits onto the outer circumferential surface of the lower shaft 84. Therefore, the dust seal 65 can prevent dust and water that have entered the inside of the housing 10 from approaching the torque sensor 40 in the axial direction from the X1 side to the X2 side of the torque sensor 40.

[0080] Furthermore, the steering column 1 has a locking device 50. The locking device 50 moves the locking pin 54 from the radially outer side of the lower shaft 84 to the radially inner side, causing the locking pin 54 to enter the groove 52a between the protrusions 52 of the key lock collar 51. As a result, the key lock collar 51 becomes unable to rotate, and the lower shaft 84 into which the key lock collar 51 is fitted becomes unable to rotate, so the steering shaft 82 becomes unable to rotate and the steering is locked.

[0081] Here, if a rotational force is applied to the steering wheel 81 due to an attempted theft of the vehicle while the steering is locked by the locking device 50, and a rotational force is input to the steering shaft 82, a radial force will act on the lower shaft 84 into which the key lock collar 51 is fitted. For example, if a clockwise force is applied to the steering shaft 82 as shown in Figure 4, the key lock collar 51 will act a clockwise force on the lock pin 54 from the protrusion 52 that contacts the lock pin 54 on its left side in the figure.

[0082] When the steering is locked, the lock pin 54 is immobile and positioned on the lower column 30. Therefore, the key lock collar 51, whose protrusion 52 abuts the lock pin 54 from the left side in Figure 4, attempts to move to the left side in Figure 4, using the point where the protrusion 52 abuts the lock pin 54 as a pivot point, due to the clockwise force input to the steering shaft 82. Consequently, the lower shaft 84 into which the key lock collar 51 is fitted also attempts to move to the left side in Figure 4, together with the key lock collar 51.

[0083] In other words, when a rotational force is applied to the steering shaft 82 while the steering is locked by the locking device 50, a force acts on the lower shaft 84, which the key lock collar 51 is fitted to, in a direction perpendicular to the axial direction, i.e., in the radial direction, causing the lower shaft 84 to move radially.

[0084] Since the lower shaft 84 is connected to the output shaft 85 via a torsion bar 86, when the lower shaft 84 moves radially, it moves radially relative to the output shaft 85. At this time, the lower shaft 84 has an end on the X2 side in the axial direction that is recessed into the inside of the output shaft 85, and a bush 88 is positioned between the lower shaft 84 and the output shaft 85 that abuts against both. Therefore, when the lower shaft 84 moves radially, the force in the direction of radial movement is transmitted to the output shaft 85 via the bush 88, and the output shaft 85 attempts to move radially together with the lower shaft 84 in the axial direction near where the bush 88 is positioned.

[0085] In this configuration, the lower shaft 84 is spline-engaged with the upper shaft 83 near its X1 end in the axial direction, and the output shaft 85 is supported by a bearing 56 in the portion of the axial direction that is X2 away from the location where the bush 88 is positioned. As a result, the radial movement of the lower shaft 84 and the output shaft 85 decreases in the portions that are farther away from the location where the bush 88 is positioned in the axial direction, towards the X1 and X2 sides. Consequently, the radial movement of the lower shaft 84 and the output shaft 85 is greater near the location where the bush 88 is positioned in the axial direction than in the portions that are farther away from the location where the bush 88 is positioned. Therefore, the lower shaft 84 and the output shaft 85 are relatively tilted in a direction that causes them to bend near the location where the bush 88 is positioned in the axial direction, and runout occurs due to the misalignment of the axes of the lower shaft 84 and the output shaft 85.

[0086] The runout caused by the relative bending of the lower shaft 84 and the output shaft 85 is corrected when the rotational force on the steering shaft 82 during steering lock is removed. The relative bending of the lower shaft 84 and the output shaft 85 returns to its original state, and the lower shaft 84 and the output shaft 85 extend coaxially.

[0087] In contrast, if the force moving the lower shaft 84 radially is large, the runout caused by the bending of the lower shaft 84 and the output shaft 85 may not return to its original position. In other words, if the runout prevention member 60 is not placed on the lower column 30, when a large force is applied to the lower shaft 84 that moves the lower shaft 84 radially, the bending of the lower shaft 84 and the output shaft 85 may not return to its original position.

[0088] In more detail, when a large rotational force is applied to the steering wheel 81 while the steering is locked by the locking device 50, and a large rotational force is input to the steering shaft 82, a large radial force acts on the lower shaft 84. The lower shaft 84 moves radially due to the large radial force, and this large force causing the lower shaft 84 to move radially is transmitted to the output shaft 85 via the bush 88. As a result, the lower shaft 84 and the output shaft 85 tilt and bend significantly relative to each other in the direction in which the bush 88 is located in the axial direction, causing runout due to the misalignment of the axes of the lower shaft 84 and the output shaft 85.

[0089] In this case, if the radial force transmitted from the lower shaft 84 to the output shaft 85 via the bush 88 is large, the bush 88 may deform due to this force. That is, when a large radial force acts on a part of the annularly formed bush 88 in the circumferential direction, it deforms in such a way that the thickness of the part subjected to the large radial force becomes thinner. If the bush 88 deforms, even if the rotational force on the steering shaft 82 is removed and the force that moves the lower shaft 84 radially is removed, the relative bending between the lower shaft 84 and the output shaft 85 will not return to its original state, and runout will continue.

[0090] Since the magnet 41 of the torque sensor 40 is attached to the lower shaft 84 and the stator 42 of the torque sensor 40 is attached to the output shaft 85, if runout between the lower shaft 84 and the output shaft 85 continues, the radial gap between the magnet 41 and the stator 42 will also continue to be in a state that has changed from the state in which the lower shaft 84 and the output shaft 85 are arranged coaxially. In other words, for example, the radial gap between the magnet 41 and the stator 42 will be of different sizes depending on the position in the circumferential direction. In this case, the magnetic flux acting from the magnet 41 to the stator 42 becomes unstable, and the output value of the steering torque detected by the torque sensor 40 becomes unstable.

[0091] In contrast, in the first embodiment, a metal runout prevention member 60 is arranged on the lower column 30, and the radial gap between the inner surface of the third portion 63 of the runout prevention member 60 and the outer surface of the metal spacer 70 is smaller than the radial gap between the magnet 41 of the torque sensor 40 and the stator 42. Therefore, when a large rotational force is input to the steering shaft 82 while the steering is locked by the locking device 50, and a large radial force is applied to the lower shaft 84, the outer surface of the metal spacer 70 that fits onto the lower shaft 84 comes into contact with the inner surface of the runout prevention member 60.

[0092] As a result, the radial movement of the lower shaft 84 is restricted, and a large force is no longer applied to the bush 88 located between the lower shaft 84 and the output shaft 85, thus suppressing deformation of the bush 88. Therefore, when the large rotational force on the steering shaft 82 during steering lock is removed, the relative bending between the lower shaft 84 and the output shaft 85 returns to its original state, and the runout between the lower shaft 84 and the output shaft 85 is eliminated, resulting in a coaxial configuration. Consequently, the radial gap between the magnet 41 of the torque sensor 40 and the stator 42 also returns to its original state, and the radial gap between the magnet 41 and the stator 42 is maintained at the size designed, allowing the torque sensor 40 to stably output the detected steering torque value.

[0093] Furthermore, it is preferable that the radial gap between the inner circumferential surface of the third portion 63 of the runout prevention member 60 and the outer circumferential surface of the metal spacer 70, which contacts the runout prevention member 60 when the lower shaft 84 moves radially, not be made too large in order to stably output the output value of the torque sensor 40. The radial gap between the inner circumferential surface of the third portion 63 of the runout prevention member 60 and the outer circumferential surface of the metal spacer 70 is preferably such that, for example, the relative inclination between the lower shaft 84 and the output shaft 85 when a radial force is applied to the lower shaft 84 is kept to less than 1.5° by the contact between the runout prevention member 60 and the metal spacer 70.

[0094] Next, the relationship between the sway prevention member 60 and the upper column 20 during a vehicle collision will be explained. Figure 5 is an explanatory diagram showing the relationship between the sway prevention member 60 and the upper column 20 when the upper column 20 moves to the side where the sway prevention member 60 is located. When a vehicle equipped with a steering device 80 is subjected to a large impact due to an accident, the driver of the vehicle may collide with the steering wheel 81. When the driver of the vehicle collides with the steering wheel 81, a large load acts on the steering shaft 82 in the direction toward the front of the vehicle, and the upper shaft 83 of the steering shaft 82 moves relative to the lower shaft 84 in the axial direction toward the front of the vehicle. In other words, the upper shaft 83 moves relative to the lower shaft 84 in the axial direction toward X2.

[0095] The upper column 20 of the housing 10 is not capable of relative axial movement with respect to the upper shaft 83, but is capable of relative axial movement with respect to the lower column 30. Therefore, when the upper shaft 83 moves relative to the lower shaft 84 in the X2 direction in the axial direction, the upper column 20 moves relative to the lower column 30 in the X2 direction in the axial direction together with the upper shaft 83.

[0096] The upper column 20 is inserted inside the lower column 30, and a runout prevention member 60 is positioned on the inner surface of the lower column 30 on the X2 side in the axial direction relative to the upper column 20. Therefore, when the upper column 20 moves significantly relative to the lower column 30 on the X2 side, the X2 side end of the upper column 20 in the axial direction reaches the position of the runout prevention member 60.

[0097] In the first embodiment, the runout prevention member 60 is sized to allow the upper column 20 to fit into the portion between the first portion 61 and the third portion 63 in the radial direction. That is, even when the upper column 20 moves towards the X2 side in the axial direction, the runout prevention member 60 is shaped in such a way that the upper column 20 does not come into contact with the first portion 61 and the third portion 63, and the upper column 20 can move to the position of the second portion 62, which is located furthest towards the X2 side of the runout prevention member 60.

[0098] As a result, even if the upper column 20 moves towards the X2 side in the axial direction during a vehicle collision, the upper column 20 is less likely to come into contact with the runout prevention member 60, and therefore the axial movement of the upper column 20 toward the X2 side is less restricted. Consequently, the upper shaft 83, which moves toward the X2 side in the axial direction, i.e., toward the front of the vehicle, along with the upper column 20, is also less likely to be restricted in its axial movement toward the front of the vehicle, and the amount of axial movement of the upper shaft 83 is increased, thus allowing for a greater absorption of collision energy.

[0099] As described above, in the steering device 80 according to the first embodiment, a runout prevention member 60 is attached to the inner circumferential surface of the lower column 30 at a position between the key lock collar 51 and the torque sensor 40 in the axial direction, thereby restricting the radial movement of the lower shaft 84 by contacting a member arranged on the lower shaft 84 from the radial outside. As a result, when a large rotational force is input to the steering shaft 82 during steering lock, causing the lower shaft 84 to move radially, the runout prevention member 60 can suppress the radial movement of the lower shaft 84. This prevents misalignment of the axes of the lower shaft 84 and the output shaft 85, and suppresses runout of the steering shaft 82.

[0100] Furthermore, since the runout prevention member 60 is made of metal, it is less likely to deform even when a large force is applied to it. Therefore, even when a large radial force is applied to the lower shaft 84, it can suppress the radial movement of the lower shaft 84 and suppress runout of the steering shaft 82. In other words, if the runout prevention member 60 is made of an elastic material such as resin, when a large radial force is applied to the lower shaft 84, the runout prevention member 60 will elastically deform, making it difficult to suppress the radial movement of the lower shaft 84 and thus difficult to suppress runout of the steering shaft 82.

[0101] In contrast, in the first embodiment, the runout prevention member 60 is made of metal and therefore has rigidity. As a result, when a large radial force acts on the lower shaft 84, the runout prevention member 60 does not undergo elastic deformation, thereby suppressing radial movement of the lower shaft 84 and suppressing large runout of the steering shaft 82. Consequently, in the first embodiment, after the large radial force on the lower shaft 84 is removed, the lower shaft 84 and the output shaft 85 of the steering shaft 82 extend coaxially, and the runout of the steering shaft 82 can be eliminated.

[0102] Therefore, it is possible to suppress the radial gap between the magnet 41 and the stator 42 of the torque sensor 40, which is caused by runout of the steering shaft 82 during steering lock, i.e., runout between the lower shaft 84 and the output shaft 85, and which varies in size depending on the circumferential position. As a result, the radial gap between the magnet 41 and the stator 42 of the torque sensor 40 is maintained at the size designed, and the torque sensor 40 can stably output the detected steering torque value. Consequently, it is possible to suppress the decrease in output stability of the torque sensor 40 after the steering lock is released, which is caused by runout of the steering shaft 82 during steering lock.

[0103] Furthermore, the anti-runout member 60 has a first portion 61, a second portion 62, and a third portion 63, and the upper column 20 is located radially between the first portion 61 and the third portion 63. Therefore, when the upper column 20 moves axially towards X2 due to an impact such as a vehicle collision, it is made difficult for the upper column 20 to come into contact with the anti-runout member 60. This ensures that the amount of movement of the upper column 20 is secured when the steering column 1 is subjected to a large impact and moves axially towards X2. As a result, the amount of collision energy absorbed when the steering column 1 is subjected to a large impact can be increased, making it easier to control the collision load.

[0104] Furthermore, a metal spacer 70 is fitted onto the lower shaft 84, and the runout prevention member 60 restricts the radial movement of the lower shaft 84 by contacting the outer surface of the metal spacer 70, thereby improving the ease of assembling the lower column 30 to the lower shaft 84. In other words, by positioning the metal spacer 70, which the runout prevention member 60 contacts, on the lower shaft 84, the inner diameter of the runout prevention member 60 can be increased. As a result, during the assembly process of the steering column 1, when passing the lower shaft 84 inside the lower column 30, the magnet 41 attached to the lower shaft 84 can be passed inside the runout prevention member 60 during assembly. Therefore, when passing the lower shaft 84 with the magnet 41 attached inside the lower column 30, the runout prevention member 60 can be attached to the inner surface of the lower column 30 while the lower shaft 84 is passed inside the lower column 30. As a result, the ease of assembling the steering column 1 can be improved, and manufacturing costs can be reduced.

[0105] Furthermore, since the runout prevention member 60 is equipped with a dust seal 65 that slides against the outer surface of the metal spacer 70, the dust seal 65 can prevent dust and water that have entered the inside of the housing 10 from approaching the torque sensor 40. This suppresses false detections by the torque sensor 40 caused by dust and water adhering to the torque sensor 40. As a result, a decrease in the output stability of the torque sensor 40 can be suppressed.

[0106] [Second Embodiment] Next, the steering device 80 according to the second embodiment will be described. Components identical to those in the first embodiment are denoted by the same reference numerals and their descriptions are omitted. The following description will focus on the differences from the first embodiment.

[0107] Figure 6 is a cross-sectional view of the main part of the steering column 1 of the steering device 80 according to the second embodiment. Similar to the steering device 80 according to the first embodiment, the steering device 80 according to the second embodiment has a metal runout prevention member 60 attached to the inner circumferential surface of the lower column 30 at a position between the key lock collar 51 and the torque sensor 40 in the axial direction, which restricts the radial movement of the lower shaft 84. In the second embodiment, unlike the first embodiment, a sealed bearing 75 is used for the runout prevention member 60. In other words, in the second embodiment, a metal spacer 70 is not fitted to the lower shaft 84, and the sealed bearing 75, which is the runout prevention member 60, restricts the radial movement of the lower shaft 84 by contacting the lower shaft 84 from the outside in the radial direction.

[0108] The sealed bearing 75 is a so-called sealed rolling bearing, positioned between the inner circumferential surface of the lower column 30 and the outer circumferential surface of the lower shaft 84, and rotatably supports the lower shaft 84 relative to the lower column 30. In other words, the sealed bearing 75 has an outer ring 75a fixed to the lower column 30, an inner ring 75b fixed to the lower shaft 84, a plurality of rolling elements 75c positioned between the outer ring 75a and the inner ring 75b, and a sealing member 75d positioned between the outer ring 75a and the inner ring 75b on both sides in the axial direction of the sealed bearing 75. The outer ring 75a, inner ring 75b and rolling elements 75c of the sealed bearing 75 are made of metal, and it has radial rigidity.

[0109] Furthermore, the sealed bearing 75 may have both its outer ring 75a and inner ring 75b press-fitted against the lower column 30 and the lower shaft 84, or the outer ring 75a may be press-fitted against the lower column 30 and the inner ring 75b may be clearance-fitted against the lower shaft 84, or the inner ring 75b may be press-fitted against the lower shaft 84 and the outer ring 75a may be clearance-fitted against the lower column 30.

[0110] In the steering device 80 according to the second embodiment, by arranging a sealed bearing 75 as a runout prevention member 60 between the lower column 30 and the lower shaft 84, even when a large radial force acts on the lower shaft 84 during steering lock, the radial movement of the lower shaft 84 can be suppressed by the sealed bearing 75. This suppresses runout of the steering shaft 82, and prevents the radial gap between the magnet 41 of the torque sensor 40 and the stator 42 from becoming different in size depending on the circumferential position due to runout between the lower shaft 84 and the output shaft 85. Therefore, the torque sensor 40 can stably output the detected steering torque value. As a result, the decrease in output stability of the torque sensor 40 after the steering lock is released due to runout of the steering shaft 82 during steering lock can be suppressed.

[0111] Furthermore, by using a sealed bearing 75 in the runout prevention member 60 without fitting a metal spacer 70 to the outer circumference of the lower shaft 84, the number of parts can be reduced. This reduces the number of assembly steps in the assembly process of the steering column 1. As a result, the ease of assembly of the steering column 1 can be improved, and manufacturing costs can be reduced.

[0112] Furthermore, by using a sealed bearing 75 having a sealing member 75d in the runout prevention member 60, dust and water that have entered the inside of the housing 10 can be prevented from approaching the torque sensor 40 by the sealing member 75d. This suppresses false detections by the torque sensor 40 caused by dust and water adhering to the torque sensor 40. As a result, a decrease in the output stability of the torque sensor 40 can be suppressed.

[0113] Furthermore, by using a sealed bearing 75 in the runout prevention member 60, the number of bearings that rotatably support the steering shaft 82 relative to the housing 10 can be increased, thereby increasing the support rigidity of the steering shaft 82. As a result, the feeling of rigidity when steering the steering wheel 81 to rotate the steering shaft 82 can be enhanced, improving the steering feel.

[0114] Furthermore, when a sealed bearing 75 is used in the runout prevention member 60, the length of the upper column 20 may be shortened while ensuring the strength of the upper column 20 so that when the upper column 20 moves to the X2 side in the axial direction due to a large impact on the steering column 1 during a vehicle collision, the upper column 20 is less likely to come into contact with the sealed bearing 75. This ensures that the amount of movement of the upper column 20 is secured, making it easier to control the collision load.

[0115] [Third Embodiment] Next, the steering device 80 according to the third embodiment will be described. Components identical to those in the first embodiment are denoted by the same reference numerals and their descriptions are omitted. The following description will focus on the differences from the first embodiment.

[0116] Figure 7 is a cross-sectional view of the main part of the steering column 1 of the steering device 80 according to the third embodiment. Similar to the steering device 80 according to the first embodiment, the steering device 80 according to the third embodiment has a metal runout prevention member 60 attached to the inner circumferential surface of the lower column 30 at a position between the key lock collar 51 and the torque sensor 40 in the axial direction, which restricts the radial movement of the lower shaft 84. The runout prevention member 60 in the third embodiment has a first part 61, a second part 62 and a third part 63, similar to the first embodiment, and a dust seal 65 is arranged on the runout prevention member 60.

[0117] In the third embodiment, unlike the first embodiment, the lower shaft 84 is not fitted with a metal spacer 70, and the key lock collar 51 has an extension 53 that extends axially towards X2. The extension 53 is positioned in the axial direction to include the position where the axial runout prevention member 60 is positioned. Therefore, the extension 53 of the key lock collar 51 is located radially inward of the runout prevention member 60.

[0118] The outer diameter of the extension 53 of the key lock collar 51 is formed to be the same diameter as the metal spacer 70 in the first embodiment. Therefore, there is a radial gap between the inner circumferential surface of the runout prevention member 60, that is, the inner circumferential surface of the third portion 63 of the runout prevention member 60, and the outer circumferential surface of the extension 53 of the key lock collar 51. Furthermore, the radial gap between the inner circumferential surface of the third portion 63 of the runout prevention member 60 and the outer circumferential surface of the extension 53 of the key lock collar 51 is smaller than the radial gap between the magnet 41 of the torque sensor 40 and the stator 42.

[0119] In this third embodiment, where the key lock collar 51 has an extension 53, the runout prevention member 60 restricts the radial movement of the lower shaft 84 by contacting the outer circumferential surface of the extension 53 of the key lock collar 51. Furthermore, the dust seal 65, which is positioned on the runout prevention member 60, also slides against the outer circumferential surface of the extension 53 of the key lock collar 51.

[0120] In the steering device 80 according to the third embodiment, the key lock collar 51 has an extension 53, and the runout prevention member 60 restricts the radial movement of the lower shaft 84 by contacting the extension 53. Therefore, even if a large radial force acts on the lower shaft 84 while the steering is locked, the radial movement of the lower shaft 84 can be suppressed. This suppresses runout of the steering shaft 82, and prevents the radial gap between the magnet 41 of the torque sensor 40 and the stator 42 from becoming different in size depending on the position in the circumferential direction due to runout between the lower shaft 84 and the output shaft 85. Consequently, the torque sensor 40 can stably output the detected steering torque value. As a result, the decrease in the output stability of the torque sensor 40 after the steering lock is released due to runout of the steering shaft 82 while the steering is locked can be suppressed.

[0121] Furthermore, because the key lock collar 51 has an extension portion 53, the runout prevention member 60 can be positioned on the lower shaft 84 without fitting a metal spacer 70 to the outer circumferential surface of the lower shaft 84, and the member that the runout prevention member 60 contacts from the radially outer side can be positioned on the lower shaft 84. This reduces the number of parts and the number of assembly steps in the assembly process of the steering column 1. As a result, the ease of assembly of the steering column 1 can be improved, and manufacturing costs can be reduced.

[0122] While preferred embodiments of this disclosure have been described above, this disclosure is not limited to those described in the embodiments described above. The configurations described as embodiments and modifications may be combined as appropriate. [Explanation of Symbols]

[0123] 1. Steering column 10 Housing 20 Upper Column 25, 55, 56 bearings 30 Roa Column 31 Opening 35 Gear Housing 36 Mounting bolts 37 Pivot Bracket 40 Torque Sensor 41 Magnets 42 stata 50 Locking device 51 Keylock Color 52 Convex part 52a Groove 53 Extension 54 lock pins 60 Runout prevention member 61 Part 1 62 Part 2 63 Part 3 65 Dust seal 65a Convex part 70 Metal Spacers 75 Sealed bearings 75a Outer ring 75b Inner ring 75c rolling element 75d sealing member 80 Steering system 81 Steering Wheel 82 Steering shaft 83 Upper Shaft 83c Inner surface 84 Lower Shaft 84b Outer surface 85 Output shaft 86 Torsion Bar 88 Bush 101, 103 Universal joint 102 Intermediate shaft 104 Pinion Shaft 105 Steering gear 105a Pinion Gear 105b Rack Bar 106 Tie Rod 110 ECU 111 Electric motor 112 Reducer 114 Worm Wheel 115 Vehicle speed sensor 116 Ignition Switch 117 Power supply

Claims

1. An upper shaft extending in the axial direction of the central axis, with one end in the axial direction connected to the steering wheel, A lower shaft is located on the other side of the axial direction relative to the upper shaft, is fitted with the upper shaft, and is capable of relative movement in the axial direction with respect to the upper shaft. An output shaft connected to the lower shaft via a torsion bar, A cylindrical upper column is positioned on the outer circumference of the upper shaft and rotatably supports the upper shaft, A cylindrical lower column is positioned on the outer circumference of the lower shaft, fits into the upper column, and is capable of relative movement in the axial direction with respect to the upper column, A torque sensor attached to the lower shaft and the output shaft detects changes in the relative rotation between the lower shaft and the output shaft, An annular key lock collar fitted to the outer circumferential surface of the lower shaft, A metal runout prevention member is attached to the inner circumferential surface of the lower column at a position between the key lock collar and the torque sensor in the axial direction, and restricts the radial movement of the lower shaft by contacting the lower shaft or a member disposed on the lower shaft from the radial outside; A steering system equipped with a steering mechanism.

2. The aforementioned runout prevention member is, It is attached to the inner circumferential surface of the lower column and has a first portion extending in the axial direction, a second portion extending inward from the other axial side of the first portion, and a third portion extending toward one side in the axial direction from the inner circumferential side of the second portion. The steering device according to claim 1, wherein the upper column is located between the first portion and the third portion in the radial direction of the central axis.

3. A metal, annular metal spacer is fitted to the outer circumferential surface of the lower shaft. The steering device according to claim 1, wherein the runout prevention member restricts the radial movement of the lower shaft by contacting the outer circumferential surface of the metal spacer.

4. The steering device according to claim 3, wherein a dust seal is provided on the runout prevention member that slides against the outer circumferential surface of the metal spacer.

5. The steering device according to claim 1, wherein the runout prevention member is a sealed bearing.

6. The key lock collar has an extension whose position in the axial direction includes the position in the axial direction where the runout prevention member is positioned. The steering device according to claim 1, wherein the runout prevention member restricts the radial movement of the lower shaft by contacting the outer circumferential surface of the extension of the key lock collar.

Images