Steering device

Abstract

To provide a steering device that is able to increase the life of a bearing.SOLUTION: A steering device includes: a steering shaft 82 which is rotated by torque input from a steering wheel 81; a housing 20 in which the steering shaft 82 is disposed; a bearing 70 which rotatably supports the steering shaft 82 with respect to the housing 20 and to which a preload in an axial direction of the steering shaft 82 is applied from the housing 20; a plurality of hole portions 45 which allow communication between inside and outside of the housing 20 and are provided in the housing 20 so as to be separated from each other in a circumferential direction of the steering shaft 82 at the same position in the axial direction; and a torque sensor 60 in which a magnetism collecting yoke assembly 61 is inserted into one hole portion 45 of the plurality of hole portions 45 and which detects a change in physical quantity associated with the rotation of the steering shaft 82.SELECTED DRAWING: Figure 2

Description

[Technical field]

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

[0002] A steering device that assists a driver in steering detects the steering torque of the driver with a torque sensor and transmits the output of a motor to an output shaft according to the detected steering torque, thereby assisting the driver in steering. For example, in the steering device described in Patent Document 1, an output shaft to which a worm wheel is connected so as to be rotatable together is rotatably supported by a bearing, and a worm attached to the rotating shaft of an electric motor is meshed with the worm wheel, making it possible to transmit the output of the electric motor to the output shaft.

[0003] The steering device described in Patent Document 1 includes a torque sensor that detects the steering torque applied by the driver, and obtains an auxiliary torque that assists the steering torque by controlling the output of an electric motor based on the steering torque detected by the torque sensor. In Patent Document 1, the torque sensor that detects the steering torque is attached to a first case that supports a bearing that rotatably supports an output shaft, and the first case is connected to a second case that supports a bearing different from the bearing supported by the first case. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2018-204755 A Summary of the Invention [Problem to be solved by the invention]

[0005] As in Patent Document 1, the bearings that rotatably support the shaft have different bearings supported by different housings, and the housings supporting the bearings are connected to each other just as the first case and second case are connected in Patent Document 1. This allows the housing supporting the bearing to apply an axial preload to the bearing, and the preload suppresses relative axial movement between the outer and inner rings of the bearing, thereby increasing the axial support rigidity when the shaft is supported by the bearing.

[0006] Here, when attaching the detection part of the torque sensor to a housing that supports a bearing, a hole that communicates between the inside and outside of the housing is formed in the housing, and the detection part of the torque sensor is attached to the housing by inserting it into the hole. However, when a hole is formed in a housing, when a housing in which the hole is formed is connected to a housing that supports a bearing different from the bearing supported by the housing, the deflection of the housing when a preload is applied to the bearing from the housing in which the hole is formed is likely to become unbalanced in the circumferential direction of the bearing.

[0007] In other words, when a hole for inserting a detection portion of a torque sensor is formed in a portion of the housing in the circumferential direction of the bearing, a difference in rigidity of the housing is likely to occur between the portion in the circumferential direction where the hole is formed and the portion other than the portion where the hole is formed, and the rigidity of the housing is likely to become unbalanced in the circumferential direction. In this case, when applying a preload to the bearing by connecting the housings together, the preload applied from the housing to the bearing is likely to become unbalanced due to the unbalanced rigidity of the housing in the circumferential direction, and the life of the bearing may be shortened due to the application of an unbalanced preload.

[0008] The present disclosure has been made in consideration of the above, and has an object to provide a steering device that can extend the life of bearings. [Means for solving the problem]

[0009] The steering device of the present disclosure includes a steering shaft that rotates due to torque input from a steering wheel, a housing on the inside of which the steering shaft is arranged, a bearing that rotatably supports the steering shaft relative to the housing and to which a preload in the axial direction of the steering shaft is applied from the housing, a plurality of holes that communicate the inside and outside of the housing and are provided in the housing at the same positions in the axial direction and spaced apart from each other in the circumferential direction of the steering shaft, and a sensor at least partially inserted into one of the plurality of holes and that detects a change in a physical quantity associated with the rotation of the steering shaft.

[0010] According to this configuration, the housing is provided with a plurality of holes, and at least a part of a sensor that detects a change in a physical quantity accompanying the rotation of the steering shaft is inserted into one of the plurality of holes formed in the housing. This makes it possible to prevent the rigidity of the housing from being reduced only in a portion in the circumferential direction where the hole is formed, due to the provision of a hole in the housing for disposing a part of the sensor in the housing. This makes it possible to prevent the preload applied from the housing to the bearing from being reduced only in a portion in the circumferential direction, due to the rigidity of the housing being reduced only in a portion in the circumferential direction. This makes it possible to prevent the load acting on the bearing from being locally increased in a portion in the circumferential direction, and to prevent early wear and failure of the bearing. As a result, the life of the bearing can be increased.

[0011] In a preferred embodiment, the holes are arranged at equal intervals in the circumferential direction.

[0012] According to this configuration, since the multiple holes are arranged at equal intervals in the circumferential direction, the portions of the housing where the rigidity is reduced by the holes can be dispersed in the circumferential direction. This makes it possible to prevent the preload applied from the housing to the bearing from being locally reduced, thereby preventing early wear and failure of the bearing. As a result, the life of the bearing can be increased.

[0013] In a preferred embodiment, the housing includes a first housing that supports the bearing and has a plurality of the holes, and a second housing that is axially connected to the first housing by bolts, the number of bolts being the same as the number of the holes in the first housing.

[0014] According to this configuration, the bolts connecting the first housing and the second housing are provided in the same number as the number of holes in the first housing, so that when the first housing and the second housing are connected with the bolts, the portions where the preload on the bearing is large can be distributed to the same number as the number of holes. This allows the preload applied from the first housing to the bearing to be distributed in the circumferential direction in accordance with the number of holes formed in the first housing. This makes it possible to prevent early wear and failure of the bearing and to extend the life of the bearing.

[0015] In a preferred embodiment, the bolts are disposed one at a time between adjacent ones of the hole portions in the circumferential direction.

[0016] According to this configuration, the bolts connecting the first housing and the second housing are arranged one by one between adjacent holes in the circumferential direction, so that it is possible to alternate in the circumferential direction between areas where the preload on the bearing is reduced due to the deflection of the first housing and areas where the preload is increased due to the fastening force of the bolts. This allows the preload applied to the bearing from the first housing to be distributed in the circumferential direction by the holes and bolts that are arranged alternately in the circumferential direction. This makes it possible to prevent early wear and failure of the bearing and to extend the life of the bearing.

[0017] In a preferred embodiment, at least one of the holes other than the hole into which the portion of the sensor is inserted is used as a drain hole for draining liquid that has entered inside the housing to the outside of the housing.

[0018] According to this configuration, at least one of the holes other than the hole into which a part of the sensor is inserted is used as a drain hole, so that when liquid such as water gets inside the housing, the liquid can be discharged from the drain hole to the outside of the housing. This makes it possible to prevent the liquid from accumulating inside the housing even if liquid gets inside the housing, and to prevent the liquid from adhering to the sensor. As a result, when the sensor detects a change in a physical quantity accompanying the rotation of the steering shaft, erroneous detection of the physical quantity caused by liquid adhering to the sensor can be suppressed.

[0019] In a preferred embodiment, the steering wheel includes an electric motor that generates an auxiliary steering torque, and a worm wheel that is fixed to the steering shaft and transmits the auxiliary steering torque generated by the electric motor to the steering shaft, the worm wheel being arranged on the opposite side of the bearing in the axial direction to the side on which the steering wheel is arranged, and the bearing has a sealing member.

[0020] According to this configuration, the bearing disposed on the steering wheel side of the worm wheel has a seal member, so that even if liquid such as water gets inside the housing, the bearing can prevent the liquid from flowing toward the worm wheel. This makes it possible to prevent corrosion of the worm wheel caused by liquid adhering to the worm wheel, and to increase the life of the reduction gear including the worm wheel.

[0021] In a preferred embodiment, the holes are formed to have the same shape.

[0022] According to this configuration, since the multiple holes formed in the housing are formed with the same shape, a part of the sensor that detects a change in a physical quantity accompanying the rotation of the steering shaft can be inserted into any of the holes. This increases the degree of freedom in layout when arranging the sensor by inserting a part of the sensor into the hole. This allows, for example, the same mold for the housing of a steering device mounted on a right-hand drive vehicle and the same mold for the housing of a steering device mounted on a left-hand drive vehicle to be used. As a result, the manufacturing cost of the steering device can be reduced.

[0023] In a preferred embodiment, the vehicle includes an electric motor that generates an auxiliary steering torque, and a worm wheel that is fixed to the steering shaft and transmits the auxiliary steering torque generated by the electric motor to the steering shaft, and the portion of the sensor is inserted into one of the multiple hole portions that is closest to the electric motor.

[0024] According to this configuration, a part of the sensor is inserted into the hole that is closest to the electric motor among the multiple holes, so that the electric motor can block an external magnetic body from approaching a part of the sensor. This can prevent the sensor from making a false detection due to a magnetic force from an external magnetic body approaching the sensor. As a result, it is possible to ensure the accuracy of the sensor in detecting a change in a physical quantity accompanying the rotation of the steering shaft. Effect of the Invention

[0025] The steering device according to the present disclosure has an effect of increasing the life of the bearings. [Brief description of the drawings]

[0026] [Figure 1] FIG. 1 is a schematic diagram of a steering device according to an embodiment. [Diagram 2] FIG. 2 is a cross-sectional view of a main part of the steering column according to the embodiment. [Diagram 3] FIG. 3 is a detailed view of the vicinity of a portion in FIG. 2 where the torque sensor is disposed. [Figure 4] FIG. 4 is a schematic diagram showing the relative positional relationship between the hole and the bolt as viewed from the direction AA in FIG. [Diagram 5] FIG. 5 is a schematic diagram showing a case where only a sensor insertion hole is formed in the main body of the first housing. [Figure 6] FIG. 6 is a schematic diagram showing a case where a plurality of holes are formed in the main body of the first housing. [Figure 7] FIG. 7 is an explanatory diagram showing the positional relationship between a magnetic flux collecting yoke assembly and an electric motor of a steering column mounted on a right-hand drive vehicle, as viewed from the BB direction in FIG. [Figure 8] FIG. 8 is a cross-sectional view of a main part showing the position of the magnetic flux collecting yoke assembly when the steering column shown in FIG. 3 is mounted on a left-hand drive vehicle. [Figure 9]FIG. 9 is an explanatory diagram showing the positional relationship between the magnetic flux collecting yoke assembly and the electric motor as viewed from the CC direction in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] Hereinafter, the present disclosure will be described in detail with reference to the drawings. Note that the present disclosure is not limited to the following modes for carrying out the invention (hereinafter, referred to as embodiments). Furthermore, the components in the following embodiments include those that a person skilled in the art can easily imagine, those that are substantially the same, and those that are within the so-called equivalent range. Furthermore, the components disclosed in the following embodiments can be appropriately combined.

[0028] [Embodiment] FIG. 1 is a schematic diagram of a steering device 80 according to an embodiment. As shown in FIG. 1, the steering device 80 includes a steering wheel 81, a steering column 10, an electric motor 111, a reduction gear 112, a universal joint 101, an intermediate shaft 102, and a universal joint 103, which are connected to a pinion shaft 104 in the order of transmission of a force applied by an operator. In the following description, the direction along the central axis AX of the steering shaft 82 is referred to as the "axial direction", the direction intersecting (perpendicular to) the axial direction is referred to as the "radial direction", and the circumferential direction centered on the axial direction is referred to as the "circumferential direction". In the following description, the upper side of the vehicle in which the steering device 80 is mounted in a normal use state is also described as the upper side of the steering device 80, the lower side of the vehicle in a normal use state is also described as the lower side of the steering device 80, and the horizontal direction of the vehicle in a normal use state is also described as the horizontal direction of the steering device 80.

[0029] A steering shaft 82 and a torque sensor 60 are disposed in the steering column 10. 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 10 will be described in detail later.

[0030] 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 joint 101 and the universal joint 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 can rotate together with the steering shaft 82.

[0031] The steering gear 105 includes 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 by the rack bar 105b. The rack bar 105b is connected to a tie rod 106. The angle of the wheels changes as the rack bar 105b moves. In other words, the steering device 80 is a rack-and-pinion type electric power steering device.

[0032] The steering device 80 further includes an ECU (Electronic Control Unit) 110 and a vehicle speed sensor 115. The electric motor 111, the vehicle speed sensor 115, and the torque sensor 60 are electrically connected to the ECU 110. The reduction gear 112 is attached to the electric motor 111. The torque sensor 60 outputs the steering torque transmitted to the steering shaft 82 to the ECU 110 by CAN (Controller Area Network) communication. The vehicle speed sensor 115 detects the traveling speed (vehicle speed) of the vehicle body on which the steering device 80 is mounted. The vehicle speed sensor 115 is provided on the vehicle body, and outputs the vehicle speed to the ECU 110 by CAN communication.

[0033] The ECU 110 controls the operation of the electric motor 111. The ECU 110 acquires signals from each of the torque sensor 60 and the vehicle speed sensor 115. When an ignition switch 116 is on, the ECU 110 is supplied with power from a power supply device 117 (for example, an on-board battery). The ECU 110 calculates an auxiliary steering command value based on the steering torque and the vehicle speed. The ECU 110 adjusts the value of power supplied to the electric motor 111 based on the auxiliary steering command value. The ECU 110 acquires information on an induced voltage of the electric motor 111 or information output from a resolver or the like provided in the electric motor 111. The force required to operate the steering wheel 81 is reduced by the ECU 110 controlling the electric motor 111.

[0034] Next, the steering column 10 will be described. Fig. 2 is a cross-sectional view of a main part of the steering column 10 according to the embodiment. The steering column 10 has a housing 20, a steering shaft 82, and a torque sensor 60. The steering shaft 82 has a steering wheel attachment portion 82a to which a steering wheel 81 (see Fig. 1) is attached at one end, and is arranged so as to be 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, and the upper shaft 83, the lower shaft 84, the output shaft 85, and the torsion bar 86 are arranged coaxially.

[0035] The steering column 10 is mounted on the vehicle with the axial direction of the steering shaft 82 aligned along the fore-and-aft direction of the vehicle when viewed from above, the side on which the steering wheel 81 is located being the rear side in the fore-and-aft direction of the vehicle, and the steering shaft 82 extending forward from the steering wheel 81.

[0036] The upper shaft 83 is a cylindrical shaft having a hollow portion. In this embodiment, the upper shaft 83 is formed in a generally hollow cylindrical shape with a diameter that varies depending on the position in the axial direction. The steering wheel attachment portion 82a of the steering shaft 82 is provided on the upper shaft 83 and is formed at one end of the upper shaft 83.

[0037] The lower shaft 84 is a solid shaft, and is disposed on the opposite side of the upper shaft 83 from the side where the steering wheel attachment portion 82a is located. The lower shaft 84 is connected to the upper shaft 83 by inserting a portion of the lower shaft 84 closer to the upper shaft 83 into the inside of the upper shaft 83. The upper shaft 83 and the lower shaft 84 are assembled such that they can be displaced relative to each other in the axial direction but cannot rotate relative to each other by abutting a portion of an inner peripheral surface 83c of the upper shaft 83 with a portion of an outer peripheral surface 84b of the lower shaft 84. In this embodiment, the upper shaft 83 and the lower shaft 84 are assembled such that they can be displaced relative to each other in the axial direction but cannot rotate relative to each other by spline-engaging an outer peripheral surface 84b of a portion of the lower shaft 84 that is inserted into the upper shaft 83 with an inner peripheral surface 83c of the upper shaft 83. In other words, the upper shaft 83 and the lower shaft 84, which are combined without being able to rotate relative to each other, are capable of expanding and contracting in the axial direction.

[0038] The output shaft 85 is disposed on the side of the lower shaft 84 opposite to the side connected to the upper shaft 83, and 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 extending in the axial direction, and the lower shaft 84 and the output shaft 85 each have a hole into which the torsion bar 86 fits. One end of the torsion bar 86 is inserted into the lower shaft 84 and fixed to the lower shaft 84, and the other end is inserted into the output shaft 85 and fixed to the output shaft 85. In this way, the lower shaft 84 and the output shaft 85 are connected via the torsion bar 86.

[0039] The housing 20 has a steering shaft 82 disposed therein and rotatably supports the steering shaft 82. The housing 20 has an upper housing 30 and a lower housing 40. The upper housing 30 and the lower housing 40 are each members having a cylindrical portion, and the steering shaft 82 is disposed inside the upper housing 30 and the lower housing 40 which are formed in a cylindrical shape.

[0040] The upper housing 30 is disposed, in the axial direction, with respect to the lower housing 40, on the side where the upper shaft 83 is disposed with respect to the lower shaft 84. In other words, the upper housing 30 is disposed, in the axial direction, with respect to the lower housing 40, on the side where the steering wheel attachment portion 82a formed on the upper shaft 83 is located. The upper shaft 83 disposed inside the upper housing 30 is disposed with a portion close to the steering wheel attachment portion 82a exposed from the inside of the upper housing 30. The steering wheel 81 (see FIG. 1) is attached to the steering wheel attachment portion 82a of the upper shaft 83, which is exposed from the inside of the upper housing 30 in this manner.

[0041] A bearing 35 is disposed inside the upper housing 30 at a position in the axial direction toward the end where the upper shaft 83 is exposed. The bearing 35 is disposed between the inner peripheral surface of the upper housing 30 and the outer peripheral surface of the upper shaft 83. As a result, the upper housing 30 supports the upper shaft 83 via the bearing 35 so as to be freely rotatable.

[0042] The lower housing 40 covers a portion of the upper housing 30 near the end opposite to the end on the side where the upper shaft 83 is exposed in the axial direction. That is, the portion of the upper housing 30 near the end opposite to the end on the side where the upper shaft 83 is exposed in the axial direction is inserted inside the lower housing 40. The upper housing 30, part of which is inserted inside the lower housing 40, is capable of moving relative to the lower housing 40 in the axial direction. Therefore, the housing 20 of the steering column 10 is capable of expanding and contracting in the axial direction by the relative movement of the upper housing 30 and the lower housing 40 in the axial direction. As a result, when the upper shaft 83 and the lower shaft 84 expand and contract in the axial direction, the upper housing 30 and the lower housing 40 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.

[0043] In other words, the upper shaft 83 and the lower shaft 84 are capable of relative movement in the axial direction, and the upper housing 30 and the lower housing 40 are also capable of relative movement in the axial direction. On the other hand, the lower shaft 84 is disposed so as to be unable to move relative to the lower housing 40 in the axial direction, and the upper shaft 83 is disposed so as to be unable to move relative to the upper housing 30 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 housing 30 also expands and contracts in the axial direction relative to the lower housing 40 in accordance with the expansion and contraction of the upper shaft 83 relative to the lower shaft 84.

[0044] The lower housing 40 has a first housing 41 and a second housing 51. The first housing 41 and the second housing 51 are located on the side where the upper housing 30 is located relative to the second housing 51 in the axial direction. The first housing 41 and the second housing 51 are axially connected by bolts 52, which are fastening members. In addition, since the first housing 41 is located on the side where the upper housing 30 is located relative to the second housing 51, the lower housing 40, which covers a portion of the upper housing 30 near the end in the axial direction, has the first housing 41 covering the upper housing 30.

[0045] The second housing 51 is disposed on the axial side opposite to the side where the upper housing 30 is located with respect to the first housing 41, and is connected to the first housing 41 by bolts 52. Therefore, the second housing 51 mainly covers the output shaft 85 of the steering shaft 82. In this manner, the second housing 51 covering the output shaft 85 of the steering shaft 82 is also provided as the housing 20 of the reduction gear 112.

[0046] A worm wheel 114 of the reduction gear 112 is disposed inside the second housing 51. The reduction gear 112 is composed of a worm (not shown) and a worm wheel 114 that meshes with the worm, and the worm is directly or indirectly attached to the drive shaft of the electric motor 111 (see FIG. 1). The worm wheel 114 is fixed to the output shaft 85 of the steering shaft 82 by being press-fitted into the output shaft 85.

[0047] 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 that time, the worm and the worm wheel 114 reduce the rotation speed of the driving force generated by the electric motor 111 and increase the torque. The reduction gear 112 increases the torque of the driving force generated by the electric motor 111 and transmits it to the output shaft 85, thereby making it possible to provide the output shaft 85 with an auxiliary steering torque. In other words, the worm wheel 114 fixed to the output shaft 85 is capable of transmitting the driving force generated by the electric motor 111 to the output shaft 85 of the steering shaft 82 as an auxiliary steering torque. The steering device 80 according to this embodiment, which is configured as described above, is a column-assist type electric power steering device in which the auxiliary steering torque generated by the electric motor 111 is applied to the steering shaft 82.

[0048] Two bearings 70, 75 are disposed on both sides of the worm wheel 114 in the axial direction, and the output shaft 85 is supported by the two bearings 70, 75. One bearing 70 is disposed on the side where the lower shaft 84 is located with respect to the worm wheel 114 in the axial direction, and is located between the first housing 41 of the lower housing 40 and the output shaft 85. The other bearing 75 is disposed on the opposite side of the side where the lower shaft 84 is located with respect to the worm wheel 114 in the axial direction, and is located between the second housing 51 of the lower housing 40 and the output shaft 85. In other words, the worm wheel 114 is disposed on the opposite side of the side where the steering wheel 81 is located with respect to the bearing 70 in the axial direction, and is disposed on the side where the steering wheel 81 is located with respect to the bearing 75 in the axial direction.

[0049] With the bearings 70, 75 arranged as above, the output shaft 85 is rotatably supported with respect to the first housing 41 and the second housing 51 of the lower housing 40 via the two bearings 70, 75. That is, the steering shaft 82 is rotatably supported with respect to the housing 20 by the bearing 35 arranged between the steering shaft 82 and the upper housing 30, the bearing 70 arranged between the steering shaft 82 and the first housing 41, and the bearing 75 arranged between the steering shaft 82 and the second housing 51.

[0050] As described above, the housing 20 rotatably supporting the steering shaft 82 is attached to the vehicle integrally with the steering shaft 82 so as to be rotatable about the rotation axis R extending in the horizontal direction. More specifically, the second housing 51 of the lower housing 40 is provided with a pivot bracket 53, and the pivot bracket 53 is formed with an insertion hole 53a opening in the horizontal direction. A pivot bolt (not shown) is inserted into the insertion hole 53a of the pivot bracket 53, and the pivot bolt is screwed into a fixing member (not shown) on the vehicle body side. This allows the housing 20 to rotate relative to the vehicle about the pivot bolt inserted into the insertion hole 53a of the pivot bracket 53, and the housing 20 is attached to the vehicle so as to be rotatable. In other words, the housing 20 is attached to the vehicle so as to be rotatable about the rotation axis R extending in the horizontal direction, with the axis of the pivot bolt extending in the horizontal direction or the axis of the insertion hole 53a of the pivot bracket 53 being the rotation axis R.

[0051] The torque sensor 60 is a sensor that detects a change in a physical quantity accompanying the rotation of the steering shaft 82. The torque sensor 60 has a magnetism collecting yoke assembly 61, a magnet 65, and a stator 66. The magnet 65 and the stator 66 are disposed inside the housing 20 in the vicinity of where the lower shaft 84 and the output shaft 85 are connected, and are disposed on the axial side of the bearing 70 that rotatably supports the output shaft 85, on which the lower shaft 84 is located. The magnet 65 is formed in an annular shape, and is fixed to the lower shaft 84. The stator 66 has a portion that is located at the same position as the magnet 65 in the axial direction, and is disposed radially outward of the magnet 65 and fixed to the output shaft 85.

[0052] The magnetism collecting yoke assembly 61 is disposed at a position having a portion that is in the same position as the magnet 65 and the stator 66 in the axial direction in the first housing 41 of the lower housing 40, and is attached to the first housing 41. The magnetism collecting yoke assembly 61 is provided as a detection unit in the torque sensor 60, and is a plug-in component that has the function of converting a change in physical quantity accompanying the rotation of the steering shaft 82 into an electrical signal.

[0053] The magnetism collecting yoke assembly 61 has a magnetism collecting yoke (not shown) and a Hall IC (not shown), and is electrically connected to the ECU 110. The magnetism collecting yoke is a member for detecting a change in magnetic flux acting on the stator 66 from the magnet 65, and is disposed near the stator 66. The Hall IC is capable of detecting a change in magnetic flux density acting on the magnetism collecting yoke, converting the detected change in magnetic flux density into an electric signal, and outputting the electric signal. Since the magnetic flux density detected by the Hall IC changes according to the magnitude of the steering torque, the magnetism collecting yoke assembly 61 transmits the magnitude of the detected steering torque to the ECU 110 by outputting an electric signal obtained by converting the change in magnetic flux density to the ECU 110. This enables the torque sensor 60 to detect the steering torque and output it to the ECU 110.

[0054] The magnetic flux collecting yoke assembly 61 is inserted into a hole 45 formed in the lower housing 40 and communicating the inside and outside of the lower housing 40 in the radial direction. That is, at least a part of the torque sensor 60 is inserted into the hole 45, and in this embodiment, the magnetic flux collecting yoke assembly 61, which is a detection unit of the torque sensor 60, is inserted into the hole 45. A plurality of holes 45 are formed in the first housing 41 of the lower housing 40 with the same shape, and the plurality of holes 45 are provided in the first housing 41 at the same positions in the axial direction and spaced apart from each other in the circumferential direction of the steering shaft 82. Specifically, the plurality of holes 45 are formed to have a portion whose axial position is the same as that of the magnet 65 and the stator 66 of the torque sensor 60. In this embodiment, two holes 45 are provided in the first housing 41, and the two holes 45 are arranged at equal intervals in the circumferential direction. In other words, the two holes 45 are formed at positions spaced apart from each other by approximately 180° in the circumferential direction.

[0055] The magnetic flux collecting yoke assembly 61 is inserted into one of the multiple holes 45 formed in the lower housing 40, and a part of the magnetic flux collecting yoke assembly 61 passes through the hole 45 and is disposed inside the lower housing 40. That is, one of the two holes 45 formed in the first housing 41 is used as a sensor insertion hole 46, and the magnetic flux collecting yoke assembly 61 is inserted into the sensor insertion hole 46 and a part of the magnetic flux collecting yoke assembly 61 is disposed inside the lower housing 40. Specifically, the two holes 45 formed in the first housing 41 are formed at positions such that one hole 45 is located at the upper end in the vertical direction and the other hole 45 is located at the lower end when the steering column 10 is mounted on the vehicle. Of the two holes 45 formed in the first housing 41, the sensor insertion hole 46 is the hole 45 located on the upper end side when the steering column 10 is mounted on the vehicle, and the magnetic collecting yoke assembly 61 is inserted into the sensor insertion hole 46 located on the upper end side.

[0056] On the other hand, the hole 45 located on the lower end side when the steering column 10 is mounted on the vehicle is used as a drain hole 47 that drains liquid that has entered the inside of the housing 20 to the outside of the housing 20. For this reason, the drain hole 47 formed in the first housing 41 is formed in the axial direction on the side where the upper housing 30 and the upper shaft 83 are located, rather than the worm wheel 114 disposed inside the second housing 51.

[0057] In this case, the drain hole 47 is preferably formed so that the portion where the hole portion 45 in the axial direction is formed includes the lowest portion in the vertical direction when viewed in the axial direction of the steering column 10 in a state where it is mounted on a vehicle. Even if the drain hole 47 does not include the lowest portion in the vertical direction, it is preferable to position the drain hole 47 as close to the lowest portion as possible.

[0058] FIG. 3 is a detailed view of the vicinity of the portion where the torque sensor 60 is disposed in FIG. 2. FIG. 4 is a schematic view showing the relative positional relationship between the hole portion 45 and the bolt 52 as viewed from the AA direction in FIG. 3. The first housing 41 and the second housing 51 of the lower housing 40 are connected by the bolt 52. The first housing 41 has a main body portion 41a in which the hole portion 45 is formed, and a flange portion 41b formed in a substantially circular plate shape that is located toward the end of the main body portion 41a opposite to the side where the upper housing 30 is located in the axial direction and has a radial size larger than that of the main body portion 41a. The portion of the second housing 51 that is connected to the first housing 41 has a radial size approximately the same as that of the flange portion 41b of the first housing 41. The first housing 41 and the second housing 51 are connected to each other by the bolt 52, with the flange portion 41b of the first housing 41 and the second housing 51 being connected to each other.

[0059] The bolts 52 connecting the first housing 41 and the second housing 51 are provided in the same number as the plurality of holes 45 of the first housing 41, and are disposed one at a time between adjacent holes 45 in the circumferential direction. In the present embodiment, two holes 45 are formed, and therefore two bolts 52 connecting the first housing 41 and the second housing 51 are also provided. Furthermore, the two bolts 52 are disposed at positions in the circumferential direction that are between adjacent holes 45 in the circumferential direction, and therefore the two bolts 52 are disposed at positions shifted by approximately 90° in the circumferential direction from the two holes 45.

[0060] In Figures 2 and 3, for the sake of convenience, the hole portion 45 and the bolt 52 are illustrated in the same cross section in order to show the radial position of the bolt 52. However, in reality, the bolt 52 is disposed at a position shifted by approximately 90° in the circumferential direction about the axis of the steering shaft 82 from the position in Figures 2 and 3.

[0061] Bearing 70 and bearing 75, which rotatably support steering shaft 82, are so-called rolling bearings. That is, bearing 70 supported by first housing 41 of lower housing 40 has an outer ring 71 fixed to first housing 41, an inner ring 72 fixed to steering shaft 82, and a plurality of rolling elements 73 arranged between the outer ring 71 and the inner ring 72. Similarly, bearing 75 supported by second housing 51 of lower housing 40 has an outer ring 76 fixed to second housing 51, an inner ring 77 fixed to steering shaft 82, and a plurality of rolling elements 78 arranged between the outer ring 76 and the inner ring 77.

[0062] Further, in a state in which the outer ring 71 of the bearing 70 is fixed to the first housing 41 and the inner ring 72 is fixed to the steering shaft 82, the lower housing 40 and the steering shaft 82 apply an axial preload to the bearing 70, which is a preload applied to the outer ring 71 and the inner ring 72 of the bearing 70 in opposite directions in the axial direction of the steering shaft 82. Similarly, in a state in which the outer ring 76 of the bearing 75 is fixed to the second housing 51 and the inner ring 77 of the bearing 75 is fixed to the steering shaft 82, the lower housing 40 and the steering shaft 82 apply an axial preload to the bearing 75, which is a preload applied to the outer ring 76 and the inner ring 77 of the bearing 75 in opposite directions in the axial direction of the steering shaft 82.

[0063] Of the bearings 70 and 75 which rotatably support the steering shaft 82, the bearing 70 rotatably supports the output shaft 85 relative to the first housing 41, and the bearing 75 rotatably supports the output shaft 85 relative to the second housing 51. In other words, the bearing 70 rotatably supports the output shaft 85, and the first housing 41 and the output shaft 85 apply an axial preload to the bearing 70, and the bearing 75 rotatably supports the output shaft 85, and the second housing 51 and the output shaft 85 apply an axial preload to the bearing 75.

[0064] In detail, the diameter of the first housing 41 at a portion opposite to the side where the second housing 51 is located relative to the outer ring 71 of the bearing 70 in the axial direction is smaller than the outer diameter of the outer ring 71, and the first housing 41 abuts against the outer ring 71 of the bearing 70 in the axial direction from the side opposite to the side where the second housing 51 is located. Also, the diameter of the second housing 51 at a portion opposite to the side where the first housing 41 is located relative to the outer ring 76 of the bearing 75 in the axial direction is smaller than the outer diameter of the outer ring 76, and the second housing 51 abuts against the outer ring 76 of the bearing 75 in the axial direction from the side opposite to the side where the first housing 41 is located.

[0065] Furthermore, the diameter of the portion of output shaft 85 between the portion to which bearing 70 is fixed and the portion to which bearing 75 is fixed is larger than the inner diameter of inner ring 72 of bearing 70 and the inner diameter of inner ring 77 of bearing 75. Therefore, output shaft 85 abuts against inner ring 72 of bearing 70 in the axial direction from the side where second housing 51 is located, and abuts against inner ring 77 of bearing 75 in the axial direction from the side where first housing 41 is located.

[0066] Furthermore, in this embodiment, the axial distance between a portion of the first housing 41 that axially abuts against the outer ring 71 of the bearing 70 and a portion of the second housing 51 that axially abuts against the outer ring 76 of the bearing 75 is smaller than the sum of the axial width of the portion of the output shaft 85 between the bearings 70 and 75, the axial width of the bearing 70, and the axial width of the bearing 75. Therefore, when the first housing 41 and the second housing 51 are connected with the bolts 52, the axial distance between the outer ring 71 of the bearing 70 and the outer ring 76 of the bearing 75 is smaller than the axial distance between the inner ring 72 of the bearing 70 and the inner ring 77 of the bearing 75.

[0067] Therefore, a biasing force in a direction to move the outer ring 71 closer to the side where the second housing 51 is located than the inner ring 72, or a biasing force in a direction to move the inner ring 72 to the opposite side of the side where the second housing 51 is located than the outer ring 71, is applied as an axial preload to the bearing 70. Similarly, a biasing force in a direction to move the outer ring 76 closer to the side where the first housing 41 is located than the inner ring 77, or a biasing force in a direction to move the inner ring 77 to the opposite side of the side where the first housing 41 is located than the outer ring 76 is applied as an axial preload to the bearing 75.

[0068] With the first housing 41 and the second housing 51 connected, the bearing 70 supported by the first housing 41 and the bearing 75 supported by the second housing 51 are thus applied with an axial preload from the lower housing 40 and the steering shaft 82. As a result, the axial preload maintains the state in which the outer ring 71 and the inner ring 72 are in contact with the rolling elements 73 of the bearing 70, and the axial preload maintains the state in which the outer ring 76 and the inner ring 77 are in contact with the rolling elements 78 of the bearing 75.

[0069] As described above, hole 45 formed in first housing 41 that applies axial preload to bearing 70 is formed to have a portion whose radial position is the same as the radial position of a portion of first housing 41 that axially abuts against outer ring 71 of bearing 70. In other words, hole 45 formed in first housing 41 is formed to have a portion that axially overlaps with a portion of first housing 41 that axially abuts against outer ring 71 of bearing 70.

[0070] Next, the operation of the steering device 80 will be described. When the steering wheel 81 is operated while driving the 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 shaft 104 to the pinion gear 105a. As a result, the steering gear 105 having 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.

[0071] The steering device 80 according to this embodiment also has an electric motor 111 that generates an auxiliary steering torque to assist the driver in steering. The electric motor 111 generates the auxiliary steering torque based on the steering torque detected by the torque sensor 60 disposed between the lower shaft 84 of the steering shaft 82 and the output shaft 85.

[0072] The torque sensor 60 detects the steering torque applied from the steering wheel 81 to the steering shaft 82 based on the angle of relative rotation between the lower shaft 84 and the output shaft 85 when they rotate relative to each other. That is, since the lower shaft 84 and the output shaft 85 are connected via the torsion bar 86, when a 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 is slightly twisted, causing the lower shaft 84 and the output shaft 85 to rotate slightly relative to each other.

[0073] In the torque sensor 60, the magnet 65 is attached to the lower shaft 84, and the stator 66 is attached to the output shaft 85, so that when the lower shaft 84 and the output shaft 85 rotate relative to each other, the magnet 65 and the stator 66 of the torque sensor 60 also rotate relative to each other. The angle of relative rotation between the magnet 65 and the stator 66 increases as the steering torque acting between the lower shaft 84 and the output shaft 85 increases.

[0074] When the magnet 65 and the stator 66 rotate relative to each other, the magnetic flux acting from the magnet 65 to the stator 66 changes. The magnetic flux collecting yoke of the magnetic flux collecting yoke assembly 61 inserted into the sensor insertion hole 46 of the first housing 41 is capable of detecting the change in the magnetic flux acting from the magnet 65 to the stator 66. Therefore, when the magnet 65 and the stator 66 rotate relative to each other in accordance with the relative rotation of the lower shaft 84 and the output shaft 85, the magnetic flux collecting yoke of the magnetic flux collecting yoke assembly 61 can detect the change in the magnetic flux acting from the magnet 65 to the stator 66.

[0075] In this way, the magnetic flux acting on the stator 66 from the magnet 65, which is detected by the magnetic flux collecting yoke of the magnetic flux collecting yoke assembly 61, changes according to the angle of relative rotation between the magnet 65 and the stator 66. The Hall IC of the magnetic flux collecting yoke assembly 61 together with the magnetic flux collecting yoke detects the magnetic flux, which changes according to the angle of relative rotation between the magnet 65 and the stator 66 detected by the magnetic flux collecting yoke, with a Hall element and converts it into an electric signal with an output circuit. The magnetic flux collecting yoke assembly 61 transmits the electric signal thus converted by the Hall IC to the ECU 110 as an output signal from the torque sensor 60. In other words, the torque sensor 60 detects the change in the magnetic flux acting on the stator 66 from the magnet 65 with the magnetic flux collecting yoke assembly 61, thereby detecting the steering torque applied to the output shaft 85 from the steering wheel 81 via the upper shaft 83 and the lower shaft 84, and transmits the detected steering torque to the ECU 110 as an electric signal.

[0076] The ECU 110 operates the electric motor 111 based on the electric signal transmitted from the torque sensor 60, and causes the electric motor 111 to generate an auxiliary steering torque. In other words, the electric signal transmitted from the magnetism collecting yoke assembly 61 of the torque sensor 60 to the ECU 110 changes according to the angle of relative rotation between the magnet 65 and the stator 66, and changes based on the steering torque acting between the lower shaft 84 and the output shaft 85. For this reason, the ECU 110 uses the electric signal transmitted from the magnetism collecting yoke assembly 61 of the torque sensor 60 as information that changes depending on the steering torque acting on the lower shaft 84 and the output shaft 85, and adjusts the value of power supplied to the electric motor 111 based on the electric signal transmitted from the magnetism collecting yoke assembly 61, causing the electric motor 111 to generate an auxiliary steering torque.

[0077] That is, the ECU 110 obtains a steering torque signal from the torque sensor 60, a vehicle speed signal from the vehicle speed sensor 115, and further obtains operation information of the electric motor 111 from a rotation detection device provided in the electric motor 111, and causes the electric motor 111 to generate an auxiliary steering torque based on the operation information, steering torque, and vehicle speed signal. 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 a worm wheel 114 attached to the drive shaft of the electric motor 111. As a result, the steering force applied to the steering wheel 81 by the driver is assisted by the auxiliary steering torque generated by the electric motor 111.

[0078] Furthermore, the steering column 10 of the steering device 80 is capable of adjusting the height position and the front-rear position of the steering wheel 81. That is, the steering column 10 is capable of adjusting the tilt position and the telescopic position of the steering wheel 81. The height position and the front-rear position of the steering wheel 81 are adjusted electrically or manually. When the height position and the front-rear position of the steering wheel 81 are adjusted electrically, an electric motor (not shown) that generates a driving force for operating the steering column 10 when adjusting these positions is mounted on the steering column 10.

[0079] When adjusting the height position of the steering wheel 81 attached to the steering shaft 82, the housing 20 and the steering shaft 82 are rotated together around a horizontally extending rotation axis R. This causes the steering wheel 81 attached to one end of the steering shaft 82 to also rotate around the rotation axis R, making it possible to adjust the height position of the steering wheel 81, i.e., the tilt position.

[0080] 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, and the fore-aft position of the steering wheel 81, i.e., the telescopic position, to be adjusted.

[0081] Furthermore, when the upper shaft 83 is moved axially relative to the lower shaft 84 in this manner, the upper housing 30 also moves axially relative to the lower housing 40 together with the upper shaft 83. Since the upper shaft 83 is rotatably supported by the upper housing 30 via the bearing 35, the upper housing 30 also moves axially together with the upper shaft 83, so that the upper shaft 83 is maintained in a state of being rotatably supported by the upper housing 30. This allows the steering column 10 to adjust the fore-aft position of the steering wheel 81 while maintaining a state in which the steering shaft 82 is rotatably supported.

[0082] Furthermore, when the driver steers the steering wheel 81, the output shaft 85 of the steering shaft 82 rotates while being supported by the bearings 70 and 75. At that time, an axial preload is applied to the bearing 70 by the first housing 41 and the output shaft 85, and an axial preload is applied to the bearing 75 by the second housing 51 and the output shaft 85. Therefore, the bearing 70 maintains a state in which the outer ring 71 and the rolling element 73, and the rolling element 73 and the inner ring 72 are in contact with each other, and the bearing 75 maintains a state in which the outer ring 76 and the rolling element 78, and the rolling element 78 and the inner ring 77 are in contact with each other.

[0083] Here, the axial preload applied to the bearing 70 is applied by the first housing 41 that abuts against the outer ring 71 of the bearing 70 in the axial direction, and the first housing 41 is formed with a sensor insertion hole 46 into which the magnetic flux collection yoke assembly 61 is inserted. For this reason, the first housing 41 is prone to have a difference in rigidity between the portion in the circumferential direction where the sensor insertion hole 46 is formed and the other portions. As a result, when the first housing 41 is connected to the second housing 51 while applying a preload to the bearing 70, the deflection of the first housing 41 due to the reaction force associated with applying the preload to the bearing 70 tends to be unbalanced in the circumferential direction.

[0084] 5 is a schematic diagram of a case where only the sensor insertion hole 46 is formed in the main body 41a of the first housing 41. When only the sensor insertion hole 46 is formed in the main body 41a of the first housing 41 as shown in FIG. 5, the rigidity of the first housing 41 becomes unbalanced in the circumferential direction. In this case, when the first housing 41 applies an axial preload to the bearing 70, the first housing 41 is likely to bend more at the position where the sensor insertion hole 46 is formed in the circumferential direction than at other positions in the circumferential direction. Therefore, the axial preload applied from the first housing 41 to the bearing 70 is likely to be smaller in the portion where the sensor insertion hole 46 is formed in the circumferential direction, because the first housing 41 is bent more.

[0085] That is, the preload applied to the bearing 70 from the first housing 41 is small at some positions in the circumferential direction, so that the outer ring 71 of the bearing 70 to which the preload is applied is likely to be tilted relative to the inner ring 72 as shown in FIG. 5. That is, the axis of the outer ring 71 of the bearing 70 is likely to be tilted relative to the inner ring 72. In this way, when the outer ring 71 of the bearing 70 is tilted relative to the inner ring 72, the load between the outer ring 71 or the inner ring 72 and the rolling elements 73 is likely to be unbalanced in the circumferential direction, and the load at some positions in the circumferential direction is likely to be large compared to when the outer ring 71 and the inner ring 72 are arranged in parallel. Also, when the outer ring 71 of the bearing 70 is tilted relative to the inner ring 72, when the outer ring 71 and the inner ring 72 rotate relatively via the rolling elements 73, the rotation resistance is likely to be large compared to when the outer ring 71 and the inner ring 72 are arranged in parallel. As a result, the bearing 70 becomes more susceptible to wear and breakdowns, and the life of the bearing 70 becomes shorter.

[0086] FIG. 6 is a schematic diagram of a case where a plurality of holes 45 are formed in the main body 41a of the first housing 41. In this embodiment, as shown in FIG. 6, a plurality of holes 45 are formed in the main body 41a of the first housing 41, and one of the holes 45 is used as a sensor insertion hole 46. Therefore, in this embodiment, the rigidity of the first housing 41 is prevented from being reduced only in a portion in the circumferential direction. As a result, when the first housing 41 applies an axial preload to the bearing 70, the first housing 41 has a distributed portion where the deflection becomes large, and the axial preload applied from the first housing 41 to the bearing 70 is prevented from being reduced only in a portion in the circumferential direction.

[0087] That is, the preload applied to the bearing 70 from the first housing 41 is suppressed from becoming small only at a certain position in the circumferential direction, and the bearing 70 to which the preload is applied maintains the outer ring 71 parallel to the inner ring 72 while being applied with an axial preload, as shown in FIG. 6. In this way, the outer ring 71 and the inner ring 72 of the bearing 70 are maintained in a parallel state, so that the load between the outer ring 71 or the inner ring 72 and the rolling element 73 is balanced in the circumferential direction. In addition, the outer ring 71 and the inner ring 72 of the bearing 70 are maintained in a parallel state, so that the rotational resistance when the outer ring 71 and the inner ring 72 rotate relatively via the rolling element 73 is reduced. As a result, the bearing 70 is less likely to wear, and the life of the bearing 70 is likely to be extended.

[0088] Furthermore, by applying an axial preload to the bearings 70 and 75 by the lower housing 40 and the output shaft 85, it is possible to increase the axial support rigidity when the output shaft 85 is supported by the bearings 70 and 75. This makes it possible to maintain a constant relative positional relationship in the axial direction between the stator 66 fixed to the output shaft 85 and the magnetism collecting yoke of the magnetism collecting yoke assembly 61. Therefore, it is possible to suppress changes in the output characteristics of the steering torque detected by the torque sensor 60 due to changes in the relative positional relationship in the axial direction between the magnetism collecting yoke of the magnetism collecting yoke assembly 61 and the stator 66.

[0089] Furthermore, the bearings 70, 75 maintain a state in which the outer rings 71, 76 and the rolling elements 73, 78, and the rolling elements 73, 78 and the inner rings 72, 77 are in contact with each other, so that even if vibrations caused when the vehicle is traveling are transmitted to the bearings 70, 75, the outer rings 71, 76 do not collide with the rolling elements 73, 78, or the rolling elements 73, 78 do not collide with the inner rings 72, 77. As a result, even if vibrations are transmitted to the bearings 70, 75, the bearings 70, 75 can rotatably support the steering shaft 82 without generating noise that would occur if the outer rings 71, 76 or the inner rings 72, 77 collide with the rolling elements 73, 78.

[0090] Here, the portion of the steering shaft 82 near the steering wheel 81 side is rotatably supported by the upper housing 30 via the bearing 35, so that a small gap is formed in the portion where the bearing 35 is arranged, connecting the inner space of the housing 20 with the outer space. In other words, since the bearing 35 is configured to have an outer ring, an inner ring, and a number of rolling elements arranged between the outer ring and the inner ring, the portions between the rolling elements form gaps that connect the inner space of the housing 20 with the outer space.

[0091] In addition, when the steering column 10 is mounted on the vehicle, the steering column 10 is attached to the vehicle with the steering shaft 82 inclined with respect to the horizontal direction so that the upper shaft 83 side is located higher than the output shaft 85 side. In other words, the steering device 80 is mounted on the vehicle with the steering gear 105 located lower than the steering wheel 81. Therefore, the steering column 10 is disposed with the steering shaft 82 inclined with respect to the horizontal direction so that the output shaft 85 side is located lower than the upper shaft 83 side. For this reason, for example, if liquid such as water is splashed near the steering wheel 81 and the liquid seeps into the inside of the housing 20 through the gap in the bearing 35, the liquid flows downward inside the housing 20 due to gravity.

[0092] If liquid seeps into the inside of the housing 20 through the gaps in the bearings 35, the liquid will flow downward due to gravity while traveling along the inner surface of the housing 20 and the surface of the steering shaft 82. For this reason, the liquid that has seeped into the inside of the housing 20 will flow along the inner surface of the housing 20 and the surface of the steering shaft 82 toward the side where the lower housing 40 and the lower shaft 84 are located.

[0093] Two holes 45 are formed in the first housing 41 of the lower housing 40, and one of the holes 45 is used as a drain hole 47 located at the lower end side of the first housing 41 when the steering column 10 is mounted on the vehicle. Therefore, liquid that has entered the inside of the housing 20 and flowed to the position of the lower housing 40 is discharged from the inside to the outside of the housing 20 through the drain hole 47 formed in the first housing 41 of the lower housing 40, and falls downward in the direction of gravity. This makes it possible to prevent liquid that has entered the inside of the housing 20 through the gap of the bearing 35 that supports the upper shaft 83 from accumulating inside the housing 20, and to prevent the liquid from adhering to the torque sensor 60.

[0094] As described above, in the steering device 80 according to this embodiment, the bearing 70 that rotatably supports the steering shaft 82 is applied with a preload in the axial direction from the housing 20, and the housing 20 is provided with a plurality of holes 45 that are spaced apart from one another in the circumferential direction and at the same axial positions. In addition, the torque sensor 60 that detects the steering torque input to the steering shaft 82 has the magnetic flux collecting yoke assembly 61, which is a part of the torque sensor 60, inserted into one of the plurality of holes 45 formed in the housing 20. Therefore, by providing the hole 45 in the housing 20 for disposing the magnetic flux collecting yoke assembly 61 of the torque sensor 60 in the housing 20, it is possible to prevent the rigidity of the housing 20 from being reduced in the circumferential direction only in a portion where the hole 45 is formed.

[0095] This makes it possible to prevent the preload applied from the housing 20 to the bearing 70 from becoming small only in a portion in the circumferential direction due to the rigidity of the housing 20 becoming low only in a portion in the circumferential direction. Therefore, the outer ring 71 of the bearing 70 to which the housing 20 applies the preload can be maintained parallel to the inner ring 72, so that the load acting between the outer ring 71 or the inner ring 72 and the rolling element 73 can be prevented from becoming locally large at a portion in the circumferential direction. As a result, early wear or failure of the bearing 70 due to the local load acting on the bearing 70 can be prevented, and the life of the bearing 70 can be increased.

[0096] Furthermore, since the multiple holes 45 formed in the housing 20 are disposed at equal intervals in the circumferential direction, the portions of the housing 20 where the rigidity is reduced by the holes 45 can be dispersed in the circumferential direction. This makes it possible to prevent the preload applied from the housing 20 to the bearing 70 from being locally reduced, so that the outer ring 71 of the bearing 70 to which the preload is applied from the housing 20 can be maintained in a parallel state to the inner ring 72. As a result, early wear and failure of the bearing 70 can be prevented, and the life of the bearing 70 can be increased.

[0097] In addition, the bolts 52 connecting the first housing 41 and the second housing 51 are provided in the same number as the number of holes 45 of the first housing 41, so that when the first housing 41 and the second housing 51 are connected by the bolts 52, the portions where the preload on the bearing 70 is large can be distributed to the same number as the number of holes 45. This allows the preload applied from the first housing 41 to the bearing 70 to be distributed in the circumferential direction in accordance with the number of holes 45 formed in the first housing 41. Therefore, the outer ring 71 of the bearing 70 to which the preload is applied by the first housing 41 can be maintained in a parallel state to the inner ring 72, so that the occurrence of early wear and failure of the bearing 70 can be suppressed. As a result, the life of the bearing 70 can be increased.

[0098] In addition, the bolts 52 connecting the first housing 41 and the second housing 51 are arranged one by one between the adjacent hole portions 45 in the circumferential direction, so that it is possible to alternate in the circumferential direction between a portion where the preload on the bearing 70 is reduced due to the deflection of the first housing 41 and a portion where the preload is increased due to the fastening force of the bolts 52. This allows the preload applied from the first housing 41 to the bearing 70 to be distributed in the circumferential direction by the hole portions 45 and the bolts 52 arranged alternately in the circumferential direction. Therefore, the outer ring 71 of the bearing 70 to which the preload is applied by the first housing 41 can be maintained in a parallel state with respect to the inner ring 72, so that it is possible to suppress early wear and failure of the bearing 70. As a result, it is possible to increase the life of the bearing 70.

[0099] Furthermore, among the multiple holes 45 formed in the first housing 41, the hole 45 different from the hole 45 into which the magnetic flux collecting yoke assembly 61 of the torque sensor 60 is inserted is used as a drain hole 47, so that when liquid such as water gets inside the housing 20, the liquid can be discharged from the drain hole 47 to the outside of the housing 20. As a result, even if liquid gets inside the housing 20, the liquid can be prevented from accumulating inside the housing 20, and the liquid can be prevented from adhering to the torque sensor 60. As a result, when the steering torque is detected by the torque sensor 60, erroneous detection of the steering torque caused by liquid adhering to the torque sensor 60 can be prevented.

[0100] Furthermore, since the multiple holes 45 formed in the first housing 41 are formed to have the same shape, the magnetic flux collecting yoke assembly 61 of the torque sensor 60 can be inserted into any of the holes 45. This increases the degree of freedom in layout when arranging the magnetic flux collecting yoke assembly 61 by inserting it into the holes 45. Therefore, for example, it is possible to share the same mold for the lower housing 40 of the steering device 80 mounted on a right-hand drive vehicle and the lower housing 40 of the steering device 80 mounted on a left-hand drive vehicle.

[0101] FIG. 7 is an explanatory diagram showing the positional relationship between the magnetic flux collecting yoke assembly 61 and the electric motor 111 of the steering column 10 mounted on a right-hand drive vehicle, and is an explanatory diagram seen from the BB direction of FIG. 3. For example, the steering column 10 shown in FIG. 3 is a steering device 80 mounted on a right-hand drive vehicle, and the magnetic flux collecting yoke assembly 61 is inserted into the upper hole portion 45, and the lower hole portion 45 is used as a drain hole 47. In addition, in the steering column 10 shown in FIG. 3, the electric motor 111 is disposed on the upper side in the vertical direction as shown in FIG. 7. In this embodiment, the electric motor 111 is disposed on the upper side in the vertical direction as shown in FIG. 7, and is disposed in a direction protruding outward in the width direction of the vehicle.

[0102] That is, when an external magnetic body approaches the magnetism collecting yoke assembly 61, the magnetism collecting yoke assembly 61 may make an erroneous detection due to the magnetic force from the magnetic body. For this reason, in the steering column 10 shown in Figs. 3 and 7, the magnetism collecting yoke assembly 61 is disposed on the side where the electric motor 111 is disposed in order to make it difficult for an external magnetic body to approach the magnetism collecting yoke assembly 61. That is, the magnetism collecting yoke assembly 61 is inserted into the hole 45 that is closest to the electric motor 111 among the multiple holes 45 formed in the lower housing 40. As a result, the electric motor 111 is disposed in the vicinity of the magnetism collecting yoke assembly 61, and therefore, it becomes difficult for an external magnetic body to approach the magnetism collecting yoke assembly 61 due to being blocked by the electric motor 111.

[0103] Fig. 8 is a cross-sectional view of a main part showing the position of the magnetic flux collecting yoke assembly 61 when the steering column 10 shown in Fig. 3 is mounted on a left-hand drive vehicle. Fig. 9 is an explanatory diagram showing the positional relationship between the magnetic flux collecting yoke assembly 61 and the electric motor 111 as seen from the CC direction in Fig. 8. When mounting a steering column 10 equivalent to the steering column 10 mounted on a right-hand drive vehicle shown in Fig. 7 on a left-hand drive vehicle, the position of the electric motor 111 needs to be swapped vertically and placed on the lower side in the vertical direction as shown in Fig. 9.

[0104] In this way, when the electric motor 111 is disposed on the lower side, in order to make it difficult for external magnetic bodies to approach the magnetism collecting yoke assembly 61, the magnetism collecting yoke assembly 61 also needs to be disposed on the side where the electric motor 111 is disposed. In other words, the magnetism collecting yoke assembly 61 also needs to be disposed on the lower side like the electric motor 111, and the magnetism collecting yoke assembly 61 is inserted and disposed in the lower hole 45 in the vertical direction that is closest to the electric motor 111 among the multiple hole portions 45. As a result, even in a steering column 10 mounted on a vehicle with a left-hand drive, external magnetic bodies are blocked by the electric motor 111 and therefore have difficulty approaching the magnetism collecting yoke assembly 61.

[0105] In this manner, when the lower hole 45 is used as the sensor insertion hole 46 and the magnetic flux collecting yoke assembly 61 is inserted into the lower hole 45, the lid 48 is inserted into the upper hole 45 and the upper hole 45 is closed by the lid 48.

[0106] In this way, by forming the multiple holes 45 in the first housing 41 to have the same shape, the magnetic flux collecting yoke assembly 61 can be inserted into any of the holes 45. This allows the first housing 41 to have the same shape for both the steering column 10 mounted on a right-hand drive vehicle and the steering column 10 mounted on a left-hand drive vehicle, and the same mold can be used for the first housing 41. As a result, the manufacturing cost of the steering device 80 can be reduced.

[0107] Furthermore, by inserting the magnetism collecting yoke assembly 61 into the hole 45 that is closest to the electric motor 111 among the multiple holes 45 formed in the lower housing 40, the electric motor 111 can block an external magnetic body from approaching the magnetism collecting yoke assembly 61. This can prevent the magnetism collecting yoke assembly 61 from making an erroneous detection due to a magnetic force from the magnetic body caused by an external magnetic body approaching the magnetism collecting yoke assembly 61. As a result, the detection accuracy of the steering torque by the torque sensor 60 can be ensured.

[0108] [Variations] In the above embodiment, the first housing 41 has two holes 45, but the number of holes 45 may be other than two, and the first housing 41 may have three or more holes 45. The number of holes 45 formed in the first housing 41 is not important as long as the holes 45 have the same shape, are positioned at the same axial positions as one another, and are equally spaced apart in the circumferential direction, regardless of the number of holes 45.

[0109] Furthermore, regardless of the number of holes 45 formed in the first housing 41, it is preferable that at least one of the holes 45 other than the hole 45 into which the magnetic flux collecting yoke assembly 61 of the torque sensor 60 is inserted be used as a drain hole 47.

[0110] In addition, the bolts 52 connecting the first housing 41 and the second housing 51 are preferably provided in the same number as the plurality of holes 45 formed in the first housing 41, and each bolt 52 is preferably arranged at a position between adjacent holes 45 in the circumferential direction. In this manner, by connecting the first housing 41 and the second housing 51 by arranging the bolts 52 in the same number as the plurality of holes 45 at a position between adjacent holes 45 in the circumferential direction, the preload applied from the first housing 41 to the bearing 70 can be distributed in the circumferential direction. As a result, regardless of the number of holes 45 and bolts 52, the outer ring 71 of the bearing 70 to which the preload is applied by the first housing 41 can be maintained parallel to the inner ring 72, thereby increasing the life of the bearing 70.

[0111] In addition, the bearing 70 arranged on the side of the worm wheel 114 where the steering wheel 81 is arranged in the axial direction is preferably a bearing 70 having a seal member. In other words, it is preferable to use a so-called sealed bearing, in which a seal member is incorporated in the bearing, for the bearing 70. In this way, by using a sealed bearing for the bearing 70 arranged on the side of the worm wheel 114 where the steering wheel 81 is arranged, even if liquid such as water gets inside the housing 20, the bearing 70 can prevent the liquid from flowing toward the worm wheel 114. This can prevent corrosion of the worm wheel 114 caused by liquid adhering to the worm wheel 114, and can increase the life of the reduction gear 112.

[0112] In the above-described embodiment, the torque sensor 60 is provided in the steering column 10, but the sensor provided in the steering column 10 may be a sensor other than the torque sensor 60. The sensor provided in the steering column 10 may be, for example, a steering angle sensor that detects the rotation angle of the steering shaft 82. In this case, a detection portion of the steering angle sensor, which is a part of the steering angle sensor, is inserted into the hole portion 45 used as the sensor insertion hole 46 out of the multiple hole portions 45 formed in the first housing 41. In this way, the type of sensor provided in the steering column 10 is not limited as long as the part of the sensor inserted into the sensor insertion hole 46 becomes a detection portion that is an insert-type component having a function of converting a change in physical quantity accompanying the rotation of the steering shaft 82 into an electrical signal.

[0113] Although the preferred embodiments of the present disclosure have been described above, the present disclosure is not limited to the above-described embodiments. The configurations described as the embodiments and modified examples may be combined as appropriate. [Explanation of symbols]

[0114] 10. Steering column 20. Housing 30 Upper housing 35 Bearings 40 Lower housing 41 1st Housing 41a Main body 41b Flange part 45 Hole 46 Sensor insertion hole 47 Drain hole 51 Second Housing 52 Volts 53 Pivot bracket 60 Torque Sensor 61 Magnetic collector yoke assembly 65 Magnet 66 Stator 70, 75 Bearings 71, 76 Outer ring 72, 77 Inner circle 73, 78 Rolling elements 80 Steering device 81 Steering Wheel 82 Steering shaft 82a Steering wheel mounting part 83 Upper Shaft 84 Lower shaft 85 Output shaft 86 Torsion bar 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. a steering shaft that rotates due to torque input from a steering wheel; a housing in which the steering shaft is disposed; a bearing that rotatably supports the steering shaft relative to the housing and to which a preload in the axial direction of the steering shaft is applied from the housing; a plurality of holes provided in the housing, the holes communicating with an inside and an outside of the housing, the holes being spaced apart from one another in a circumferential direction of the steering shaft and positioned at the same positions in the axial direction; a sensor at least partially inserted into one of the plurality of holes and configured to detect a change in a physical quantity caused by rotation of the steering shaft; A steering device comprising:

2. The steering device according to claim 1 , wherein the plurality of holes are disposed at equal intervals in the circumferential direction.

3. the housing includes a first housing that supports the bearing and has a plurality of the holes, and a second housing that is connected to the first housing in the axial direction by bolts, 3. The steering device according to claim 1, wherein the number of the bolts is the same as the number of the holes formed in the first housing.

4. The steering device according to claim 3 , wherein the bolts are disposed one at a time between the hole portions adjacent to each other in the circumferential direction.

5. 3. The steering device according to claim 1, wherein at least one of the holes other than the hole into which the portion of the sensor is inserted is used as a drain hole for discharging liquid that has entered inside the housing to the outside of the housing.

6. an electric motor that generates an auxiliary steering torque; a worm wheel fixed to the steering shaft and configured to transmit an auxiliary steering torque generated by the electric motor to the steering shaft; Equipped with the worm wheel is disposed on an opposite side to a side on which the steering wheel is disposed with respect to the bearing in the axial direction, 3. The steering apparatus according to claim 1, wherein the bearing comprises a seal member.

7. The steering device according to claim 1 or 2, wherein the plurality of holes are formed to have the same shape.

8. an electric motor that generates an auxiliary steering torque; a worm wheel fixed to the steering shaft and configured to transmit an auxiliary steering torque generated by the electric motor to the steering shaft; Equipped with 3. The steering device according to claim 1, wherein the portion of the sensor is inserted into one of the plurality of holes that is closest to the electric motor.

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