Steering shaft

Abstract

The present invention realizes a steering shaft having a structure capable of suppressing a change in sliding resistance even when the entire length is changed. Any one of the inner diameter side clamping part (19) and the outer diameter side clamping part (31) is provided with at least one non-clamping part (23) which is not clamped with the other clamping part at the middle part in the axial direction, and clamping parts which respectively have an effective length X are arranged on the two sides of the non-clamping part (23) of the one clamping part in the axial direction. The non-engagement section (23) has an axial dimension that is the same length as the effective length X, and the other engagement section has an effective length Y that is a length 2X that is twice the effective length X.

Description

Technical Field

[0001] The present disclosure relates to a steering shaft. Background Art

[0002] In recent years, the development of installing autonomous driving technology in vehicles has led to the widespread popularization of autonomous driving vehicles that have achieved SAE (Society of Automotive Engineers) Level 2 (partial driving automation) and also the popularization of autonomous driving vehicles that have achieved Level 3 (conditional driving automation).

[0003] At autonomous driving level 2, if predetermined conditions are met, the driver can drive the vehicle with his hands off the steering wheel. In an autonomous driving vehicle equipped with autonomous driving technology at autonomous driving level 2 or higher, especially autonomous driving level 3 or higher, the necessity for the driver to operate the steering wheel becomes low. Therefore, in an autonomous driving vehicle, when executing autonomous driving, it is less necessary to place the steering wheel in a position within the reach of the driver in advance, and in order to ensure a wider space in front of the driver's seat, it is desirable to retreat the steering wheel to a greater extent forward.

[0004] In order to largely retract the steering wheel forward, it is necessary to make the telescopic stroke of the steering shaft to which the steering wheel is fixed longer than that of the steering shaft of the conventional structure, thereby lengthening the stroke of the steering shaft.

[0005] The steering shaft includes an inner shaft and an outer shaft, and is configured by spline engagement between an outer spline portion provided on the outer circumference of the inner shaft and an inner spline portion provided on the inner circumference of the outer shaft. In order to increase the stroke of the steering shaft, it is considered to increase the total length of the outer spline portion and the inner spline portion.

[0006] As a technology applicable to such a structure, Japanese Patent Application Laid-Open No. 2017-052514 discloses covering external spline teeth with a resin coating in order to reduce the sliding resistance of the steering shaft when performing a telescopic operation.

[0007] Prior art literature

[0008] Patent Literature

[0009] Patent Document 1: Japanese Patent Application Publication No. 2017-52514 Summary of the invention

[0010] Problems to be solved by the invention

[0011] Fig. 20 and Fig.21 An undisclosed steering shaft 100 that was considered by the inventors before completing the present disclosure is shown.

[0012] The steering shaft 100 includes an outer shaft 102 disposed on one axial side and an inner shaft 101 disposed on the other axial side. The inner shaft 101 has an outer spline portion 106 constituting an inner diameter side engagement portion at an end portion on one axial side of the outer peripheral surface. The outer spline portion 106 is elongated in the axial direction and has a plurality of outer spline teeth 103 disposed in the circumferential direction.

[0013] The outer shaft 102 has an inner spline portion 107 constituting an outer diameter side engagement portion at the end portion on the other axial side of the inner peripheral surface. The inner spline portion 107 engages with the outer spline portion 106 in a manner capable of transmitting torque and performing axial relative displacement. The inner spline portion 107 is elongated in the axial direction and has a plurality of inner spline teeth 105 arranged in the circumferential direction.

[0014] The external spline portion 106 includes a resin coating 104 covering a range from an end portion on one axial side to a middle portion thereof.

[0015] The effective length of the outer spline portion 106 is defined as the axial dimension of the portion of the outer spline portion 106 that can be engaged with the inner spline portion 107 via the resin coating 104. When the engagement length E of the outer spline portion 106 and the inner spline portion 107 in the state where the full length of the steering shaft 100 is extended to the maximum is set to X, the effective length of the outer spline portion 106 is 3X. The axial dimension of the resin coating 104 is substantially the same as the effective length 3X of the outer spline portion 106.

[0016] The value of "X" is set to a value of about 20 mm in a steering shaft that is not intended to have a longer stroke, but is set to a value of 30 mm or more in a case where a steering shaft is intended to have a longer stroke.

[0017] In the example shown in the figure, the effective length of the internal spline portion 107 is 2X.

[0018] In the conventional steering shaft 100, when the total length is changed, the engagement length E of the outer spline portion 106 and the inner spline portion 107 is as follows: Fig.21 (A)~ Fig.21 The changes shown in (D).

[0019] Fig.21 (A) shows a state in which the steering shaft 100 is extended to its full length to its maximum. The engagement length E in the state in which the steering shaft 100 is extended to its full length to its maximum is X.

[0020] Fig.21 (B) shows that the total length of the steering shaft 100 is increased from Fig.21 The state (A) of the steering shaft 100 is contracted by a stroke equal to X. Fig.21 The state of (A) is Fig.21 As the state (B) is contracted, the engagement length E gradually increases and finally becomes 2X.

[0021] Fig.21 (C) shows that the total length of the steering shaft 100 is increased from Fig.21 The state (B) is further contracted by a stroke equal to X. Fig.21 The state of (B) is Fig.21 When the state (C) is contracted, the engagement length E remains unchanged at 2X.

[0022] Fig.21 (D) shows that the total length of the steering shaft 100 is increased from Fig.21 The state (C) is further contracted by a stroke equal to X, and the total length of the steering shaft 100 is contracted to the maximum. Fig.21 The state of (C) Fig.21 As the state (D) of the sleeve contracts, the engagement length E gradually decreases and finally becomes X.

[0023] As the total length of the steering shaft 100 changes, the engagement length E changes. If the engagement length E changes, the friction force of the engagement portion between the outer spline portion 106 and the inner spline portion 107 changes, so the sliding resistance between the outer spline portion 106 and the inner spline portion 107 that depends on the friction force also changes according to the change in the engagement length E.

[0024] When the sliding resistance when the engagement length is X is set to α, the relationship between the sliding resistance and the stroke amount is as follows: Fig. 22 That is, the sliding resistance of the steering shaft 100 changes when the engagement length E changes with the increase or decrease of the stroke amount, and remains constant when the engagement length E remains constant regardless of the increase or decrease of the stroke amount. Fig. 22 The horizontal axis shows the stroke amount from the state where the full length of the steering shaft 100 is extended to the maximum. Fig. 22 The vertical axis shows the magnitude of the sliding resistance. The total length is shown in parentheses next to the stroke.

[0025] When the sliding resistance changes with the change of the engagement length, in a manual steering device where the driver manually adjusts the front-rear position of the steering wheel, the force required to adjust the front-rear position changes, which may give the driver a sense of disharmony and discomfort. In an electric steering device where the front-rear position of the steering wheel is electrically adjusted, the driving sound of an actuator such as an electric motor changes, which may give the driver and passengers a sense of discomfort. When the steering shaft 100 is lengthened in stroke, the change in the engagement length becomes larger, so the variation range of the sliding resistance also becomes larger, and the above-mentioned problem may become significant.

[0026] Fig.23The following shows another undisclosed steering shaft 100a that the inventors considered before completing the present disclosure. In the steering shaft 100a, in order to ensure the same telescopic stroke as the steering shaft 100, the effective length of the outer spline portion 106a of the inner shaft 101a is set to 4X, and the effective length of the inner spline portion 107a of the outer shaft 102a is set to X.

[0027] According to such a structure, even when the total length of the steering shaft 100a is changed, the engagement length E does not change and can be kept constant at the same length as X, so the sliding resistance can also be kept constant. However, since the axial dimension of the outer spline portion 106a is too large, it is easy to bend during manufacturing, and there is a possibility that the productivity of the inner shaft 101a will be reduced.

[0028] It is also conceivable to set the effective length of the inner spline portion of the outer shaft to 4X and the effective length of the outer spline portion of the inner shaft to X. However, in this case, the axial dimension of the inner spline portion is too large, so there is a problem that the productivity of the outer shaft may be reduced.

[0029] An object of the present disclosure is to provide a steering shaft which can suppress a change in sliding resistance accompanying a change in an engagement length between an inner shaft and an outer shaft when the total length of the steering shaft is changed, particularly in a structure in which the stroke of the steering shaft is increased.

[0030] Solutions to Solve Problems

[0031] A steering shaft according to one embodiment of the present disclosure includes:

[0032] an inner shaft having an inner diameter side engaging portion at an end portion on one axial side of an outer peripheral surface; and

[0033] The outer shaft has an outer diameter side engagement portion at the end portion on the other axial side of the inner peripheral surface, and the outer diameter side engagement portion engages with the inner diameter side engagement portion in a manner capable of transmitting torque and being relatively displaceable in the axial direction.

[0034] The engaging portion of either the inner diameter side engaging portion or the outer diameter side engaging portion has at least one non-engaging portion in the axial middle portion that is not engaged with the engaging portion of the other of the inner diameter side engaging portion or the outer diameter side engaging portion. The engageable portions arranged on both axial sides of the non-engaging portion in the engaging portion of the one of the above-mentioned parts respectively have an effective length X, and the non-engaging portion has an axial dimension having the same length as the effective length X. That is, the engaging portion of the one of the above-mentioned parts has an axial length (3X) that is three times the effective length X as a whole, and an axial dimension (2X) of the engageable portion that is twice the effective length X.

[0035] The other of the inner diameter side engagement portion and the outer diameter side engagement portion has an effective length Y that is twice the effective length X (=2X).

[0036] The effective length X is defined by the axial dimension of the portion of each of the engageable portions constituting the above-mentioned one engaging portion that engages with the above-mentioned other engaging portion, and is equal to the engaging length of the above-mentioned one engaging portion and the above-mentioned other engaging portion when the full length of the steering shaft is maximized.

[0037] The engaging portion of one of the above-mentioned parties may include one non-engaging portion and two engaging portions. In this case, the engaging portion, the non-engaging portion, and the engaging portion are arranged in the axial direction in the order of the engaging portion, the non-engaging portion, and the engaging portion. Alternatively, the engaging portion of one of the above-mentioned parties may include two non-engaging portions and three engaging portions. In this case, the engaging portion, the non-engaging portion, the engaging portion, the non-engaging portion, and the engaging portion are arranged in the axial direction in the order of the engaging portion, the non-engaging portion, the engaging portion, the non-engaging portion, and the engaging portion. Furthermore, the engaging portion of one of the above-mentioned parties may include more than three non-engaging portions and the number of engaging portions obtained by adding one to the number of the non-engaging portions.

[0038] The above-mentioned inner diameter side engaging portion can be, for example, an external tooth portion formed by a plurality of external teeth such as an external spline portion, an external serration portion, or an engaging structure in which the cross-sectional profile of the outer peripheral surface is non-circular. The above-mentioned outer diameter side engaging portion can be, for example, an internal tooth portion formed by a plurality of internal teeth such as an internal spline portion, an internal serration portion, or an engaging structure in which the cross-sectional profile of the inner peripheral surface is non-circular.

[0039] In a steering shaft of one embodiment of the present disclosure, the inner diameter side engaging portion can be composed of the engaging portion of one of the above-mentioned parties, and the outer diameter side engaging portion can be composed of the engaging portion of the other of the above-mentioned parties. In this case, the engaging portion constituting the inner diameter side engaging portion can be composed of the outer tooth portion, and the outer diameter side engaging portion can be composed of the inner tooth portion. Furthermore, the effective length X is defined by the axial dimension of the portion of the plurality of outer teeth constituting the outer tooth portion that engages with the plurality of inner teeth.

[0040] In the steering shaft according to one aspect of the present disclosure, the non-engaging portion may be formed of a cylindrical surface having an outer diameter that is equal to or smaller than a tooth root diameter of the plurality of external teeth.

[0041] In a steering shaft of one embodiment of the present disclosure, the inner shaft may include a shaft body and the inner diameter side engaging portion provided on the outer peripheral surface, and the inner diameter engaging portion may include a resin coating covering the outer peripheral surface of the end portion on one axial side of the shaft body. In this case, the inner diameter side engaging portion may include an anti-slip portion for inhibiting the resin coating from moving relative to the shaft body in the axial direction. The anti-slip portion may be composed of a groove, a recessed portion, a ridge, a convex portion, or the like.

[0042] In a steering shaft of one embodiment of the present disclosure, the outer diameter side engaging portion can be composed of the engaging portion of one of the above-mentioned parties, and the inner diameter side engaging portion can be composed of the engaging portion of the other of the above-mentioned parties. In this case, the engaging portion constituting the outer diameter side engaging portion can be composed of the inner tooth portion, and the inner diameter side engaging portion can be composed of the outer tooth portion. Furthermore, the effective length X is defined by the axial dimension of the portion of the plurality of internal teeth constituting the inner tooth portion that engages with the plurality of external teeth.

[0043] In a steering shaft of one embodiment of the present disclosure, the external tooth portion of the inner diameter side engaging portion is composed of an external spline portion. In this case, the plurality of external teeth are composed of external spline teeth. Furthermore, the internal tooth portion of the outer diameter side engaging portion is composed of an internal spline portion. In this case, the plurality of internal teeth are composed of internal spline teeth.

[0044] In a steering shaft of one embodiment of the present disclosure, the outer tooth portion of the inner diameter side engaging portion is composed of an outer serration portion. In this case, the plurality of outer teeth are composed of outer serrations. And, the inner tooth portion of the outer diameter side engaging portion is composed of an inner serration portion. In this case, the plurality of inner teeth are composed of inner serrations.

[0045] In a steering shaft of one embodiment of the present invention, the above-mentioned inner diameter side snap-in portion is composed of a snap-in structure whose cross-sectional contour shape of the outer peripheral surface is a non-circular shape such as a circle with a notch, a polygon, etc., and the above-mentioned outer diameter side snap-in structure is composed of a snap-in structure whose cross-sectional contour shape of the inner peripheral surface is a non-circular shape such as a circle with a notch, a polygon, etc.

[0046] In the steering shaft according to one aspect of the present disclosure, when the number of the non-engaging portion is one, the effective length X is 30 mm or more, and preferably 40 mm or more.

[0047] The effects of the invention are as follows.

[0048] According to the steering shaft of one aspect of the present disclosure, particularly in a structure in which the steering shaft has a longer stroke, even when the total length of the steering shaft is changed, it is possible to suppress a change in sliding resistance accompanying a change in the engagement length between the inner shaft and the outer shaft. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 1 is a schematic diagram showing a steer-by-wire steering device including a steering shaft according to a first example of an embodiment of the present disclosure.

[0050] Figure 2 This is an end view of a steer-by-wire steering unit including a steering shaft according to a first example, as viewed from the rear side.

[0051] Figure 3 It is a perspective view showing a steer-by-wire type steering unit including a steering shaft according to a first example.

[0052] Figure 4 It is a cross-sectional view of the steering shaft of the first example.

[0053] Figure 5 This is an exploded sectional view of the steering shaft of the first example.

[0054] Figure 6 yes Figure 4 A partial enlarged view of .

[0055] Figure 7 It is a partially enlarged schematic cross-sectional view of an inner shaft constituting the steering shaft of the first example.

[0056] Figure 8 (A) is Figure 7 AA section view, Figure 8 (B) is a modified example of the first example. Figure 8 (A) Equivalent figure.

[0057] Fig. 9 (A) is a cross-sectional view showing a state where the full length of the steering shaft of the first example is extended to the maximum. Fig. 9 (B) shows that the total length is from Fig. 9 (A) is a cross-sectional view of a state where the stroke amount X is contracted, Fig. 9 (C) shows that the total length is from Fig. 9 (B) is a cross-sectional view of the state where the stroke amount X is contracted, Fig. 9 (D) is a cross-sectional view showing a state in which the entire length is contracted to the maximum.

[0058] Fig.10 This is a diagram schematically showing the relationship between the stroke amount and the magnitude of the sliding resistance regarding the steering shaft of the first example.

[0059] Fig.11 It is a partially enlarged schematic cross-sectional view of an inner shaft of a steering shaft constituting a second example of an embodiment of the present disclosure.

[0060] Fig.12 This is an enlarged view of a main part of a modified example of the second example.

[0061] Fig.13 It is a partially enlarged perspective view of an inner shaft of a steering shaft constituting a third example of an embodiment of the present disclosure.

[0062] Fig.14 It is a perspective view showing a method of achieving circumferential positioning of the inner shaft when a resin coating is formed on the inner shaft of the third example.

[0063] Fig.15 (A) is an end view of the inner shaft of the third example as viewed from one axial side. Fig.15(B) is a diagram showing a state where a resin coating is formed. Fig.15 Enlarged view of part B of (A).

[0064] Fig.16 It is a perspective view of a shaft body constituting an inner shaft of a steering shaft according to a fourth example of an embodiment of the present disclosure.

[0065] Fig.17 (A)~ Fig.17 (D) is a perspective view showing the shaft body of four examples of modified examples of the fourth example.

[0066] Fig.18 The fifth example of the embodiment of the present disclosure is Figure 6 Quite a picture.

[0067] Fig.19 The sixth example of the embodiment of the present disclosure is Figure 6 Quite a picture.

[0068] Fig. 20 It is an exploded sectional view of the steering shaft of the prior invention.

[0069] Fig.21 (A) is a cross-sectional view showing a state where the entire length of the steering shaft of the prior invention is extended to the maximum. Fig.21 (B) shows that the total length is from Fig.21 (A) is a cross-sectional view of a state where the stroke amount X is contracted, Fig.21 (C) shows that the total length is from Fig.21 (B) is a cross-sectional view of the state where the stroke amount X is contracted, Fig.21 (D) is a cross-sectional view showing a state in which the entire length is contracted to the maximum.

[0070] Fig. 22 The following is a diagram schematically showing the relationship between the stroke amount and the magnitude of the sliding resistance in relation to the steering shaft of the prior invention.

[0071] Fig.23 This is an exploded cross-sectional view showing a steering shaft of another example of the prior invention. DETAILED DESCRIPTION

[0072] [First example]

[0073] use Figures 1 to 10 The first example of the embodiment of the present disclosure is described. In this example, the steering shaft of the present disclosure is applied to a steer-by-wire steering device for an autonomous driving vehicle. In addition, in the following description, the front-to-back direction refers to the front-to-back direction of the vehicle, the up-down direction refers to the up-down direction of the vehicle, and the width direction refers to the width direction of the vehicle.

[0074] [Overall structure of the steering device]

[0075] The steering device 1 of this example is a steer-by-wire type steering device. Figure 1 As shown in the overall structure in FIG, the steering device 1 includes a steering unit 3 to which a steering wheel 2 is mounted, a wheel steering unit 5 for steering a pair of steered wheels 4, and a control device (ECU) 6. The steering device 1 has a linkless structure in which the steering unit 3 and the wheel steering unit 5 are electrically connected but not mechanically connected.

[0076] In the steering unit 3, the driver's operation of the steering wheel 2 is measured by a torque sensor and a steering angle sensor (not shown), and the measurement results are output to the control device 6. Various signals indicating the driving conditions, such as the steering torque measured by the torque sensor, the steering angle measured by the steering angle sensor, the vehicle speed, the yaw rate, and the acceleration, are input to the control device 6. Based on the various signals indicating the driving conditions, the control device 6 drives the wheel steering actuator 7 provided in the wheel steering unit 5. As a result, the linear motion components such as the rack shaft and the screw shaft are displaced in the width direction, and the pair of steering tie rods 8 are pushed and pulled, and the steering angle is given to the pair of steered wheels 4.

[0077] The control device 6 applies the reaction force of the reaction force generating device 10 provided in the steering unit 3 to the motor 62 (see Figure 2 ) is driven to control the steering wheel 2 and apply a steering reaction force corresponding to the driving conditions.

[0078] [Steering unit]

[0079] The steering unit 3 includes a position adjustment device 9 for adjusting the position of the steering wheel 2 and a reaction force generation device 10 for applying a steering reaction force to the steering wheel 2 .

[0080] The position adjusting device 9 includes a telescopic mechanism for adjusting the front-rear position of the steering wheel 2 and a tilting mechanism for adjusting the up-down position of the steering wheel 2. The position adjusting device 9 has a function of largely retracting the steering wheel 2 forward during automatic driving.

[0081] The position adjustment device 9 includes a steering shaft 11 , a steering column 12 , a lower telescopic actuator 13 , an upper telescopic actuator 14 , and a tilt actuator 15 .

[0082] 〈Steering shaft〉

[0083] The steering shaft 11 is configured to be extendable and retractable in its entire length, and is rotatably supported inside the steering column 12 by a plurality of rolling bearings 16 .

[0084] The steering wheel 2 is fixed to the rear end of the steering shaft 11. The front end of the steering shaft 11 is connected to the output shaft 63 constituting the reaction force generating device 10 via a torque transmission joint (not shown).

[0085] The steering shaft 11 includes an outer shaft 18 disposed on one axial side and an inner shaft 17 disposed on the other axial side. The inner shaft 17 has an inner diameter side engagement portion 19 at an end portion on one axial side of the outer peripheral surface. The outer shaft 18 has an outer diameter side engagement portion 31 that engages with the inner diameter side engagement portion 19 in a manner that can transmit torque and can perform relative displacement in the axial direction.

[0086] In this example, one axial side corresponds to the rear side, and the other axial side corresponds to the front side. However, when implementing the present disclosure, one axial side can also be regarded as the front side, and the other axial side can be regarded as the rear side.

[0087] The steering shaft 11 is configured to be able to extend and retract its entire length by combining the inner diameter side engagement portion 19 of the inner shaft 17 and the outer diameter side engagement portion 31 of the outer shaft 18. In particular, the steering shaft 11 has a longer extension stroke than a conventional steering shaft that can only adjust the front-rear position of the steering wheel 2 in order to retract the steering wheel 2 to a greater extent forward during automatic driving.

[0088] Inner Axis

[0089] The inner shaft 17 is integrally formed of an iron alloy such as carbon steel or a light alloy such as aluminum alloy, magnesium alloy, titanium alloy, etc. The inner shaft 17 is formed in a solid shape or a hollow cylindrical shape.

[0090] In this example, the inner diameter side engagement portion 19 of the inner shaft 17 is equivalent to one engagement portion. The inner diameter side engagement portion 19 is provided with a non-engaging portion 23 which is not engaged with the outer diameter side engagement portion 31 of the outer shaft 18 in the middle portion in the axial direction, and the outer diameter side engagement portion 31 of the outer shaft 18 is equivalent to the other engagement portion. The first engagement portions 22a and 22b which are equivalent to two engageable portions are arranged on both sides of the non-engaging portion 23 in the axial direction. The first engagement portions 22a and 22b have an effective length X respectively. The non-engaging portion 23 has an axial dimension having a length equal to the effective length X.

[0091] That is, the inner diameter side engagement portion 19 includes one non-engaging portion 23 and two first engagement portions 22a and 22b. In the inner diameter side engagement portion 19, the first engagement portion 22a, the non-engaging portion 23, and the first engagement portion 22b are arranged in this order in the axial direction.

[0092] In the case of implementing the present disclosure, the inner diameter side engaging portion can have two non-engaging portions and three first engaging portions. In this case, the first engaging portion, the non-engaging portion, the first engaging portion, the non-engaging portion, and the first engaging portion are arranged in the order. Moreover, the engaging portion of the above-mentioned one side can have more than three non-engaging portions and the number of first engaging portions obtained by adding one to the number of the non-engaging portions.

[0093] The inner diameter side engagement portion 19 can be constituted by, for example, an external tooth portion formed of a plurality of external teeth such as an external spline portion or an external serration portion, or an engagement portion having a non-circular cross-sectional profile of the outer peripheral surface.

[0094] The first engagement portions 22a and 22b constituting the inner diameter side engagement portion 19 are respectively constituted by an external tooth portion 86 in which a plurality of external teeth 25 are arranged in the circumferential direction. The plurality of external teeth 25 are elongated in the axial direction and arranged in the circumferential direction. The plurality of external teeth 25 in this example are arranged at equal intervals in the circumferential direction. The tooth thickness and tooth height of each of the plurality of external teeth 25 are constant in the axial direction.

[0095] In the first engagement portions 22a and 22b, the number, pitch, tooth thickness, tooth height and arrangement phase of the plurality of external teeth 25 are the same in the first engagement portion 22a arranged on one axial side and the first engagement portion 22b arranged on the other axial side.

[0096] In this example, the external teeth 86 of the first engagement portions 22a and 22b constituting the inner diameter side engagement portion 19 are constituted by external spline portions. The plurality of external teeth 25 are respectively constituted by external spline teeth.

[0097] The first engagement portion 22a on one axial side has a chamfered portion 26 at an end portion on one axial side.

[0098] The non-engaging portion 23 is disposed between the first engaging portions 22a and 22b in the axial direction. The non-engaging portion 23 is formed of a cylindrical surface whose outer diameter does not change in the axial direction. The non-engaging portion 23 has an outer diameter smaller than the root diameter of the plurality of external teeth 25 constituting the first engaging portions 22a and 22b.

[0099] In the case of implementing the present disclosure, the outer peripheral surface shape of the non-engaging portion is not limited to a cylindrical surface, and other shapes can be adopted if it does not interfere with the outer diameter side engaging portion of the outer shaft. Specifically, the non-engaging portion has a shape that can be axially displaced relative to the outer diameter side engaging portion and is not engaged to transmit torque. For example, the non-engaging portion can also be composed of a plurality of teeth with a lower tooth height than the plurality of external teeth 25 and / or a smaller tooth width than the plurality of external teeth 25 arranged in the circumferential direction.

[0100] The inner diameter side engagement portion 19 of this example does not have external teeth that are continuous over the entire axial length of the inner diameter side engagement portion 19 , but has external teeth portions 86 composed of external teeth 25 only on both axial sides of the inner diameter side engagement portion 19 excluding the non-engaging portion 23 .

[0101] The first engagement portions 22a and 22b have the same effective length X. The effective length X is defined by the axial dimension of the portion of each of the first engagement portions 22a and 22b constituting the inner diameter side engagement portion 19 that engages with the outer diameter side engagement portion 31, and is equal to the engagement length of the inner diameter side engagement portion 19 and the outer diameter side engagement portion 31 in a state where the full length of the steering shaft 11 is extended to the maximum.

[0102] The portion of each of the first engagement portions 22 a and 22 b that engages with the outer diameter side engagement portion 31 is a portion that can contribute to the transmission of torque when torque is transmitted between the inner shaft 17 and the outer shaft 18 .

[0103] In this example, the entire axial length of the first engaging portion 22a including the chamfered portion 26 provided at one end portion in the axial direction is the effective length X. However, when the chamfered portion 26 does not contribute to torque transmission, the axial dimension of the axial range of the first engaging portion 22a excluding the chamfered portion 26 is the effective length X.

[0104] The non-engaging portion 23 has an axial dimension L that is the same as the effective length X of each of the first engaging portions 22a and 22b. 23 (L 23 =X).

[0105] In order to increase the stroke of the steering shaft 11, "X" as a reference dimension is set to a value of 30 mm or more. In this example, "X" is about 50 mm.

[0106] In this example, the inner diameter side engagement portion 19 is provided with a resin coating 27. Specifically, the inner shaft 17 is composed of a shaft body 69 and a resin coating 27. The shaft body 69 has an inner diameter side engagement core portion 70 provided on the outer peripheral surface of the end portion on one side in the axial direction, a connecting portion 20 arranged at the end portion on the other side in the axial direction, and an intermediate shaft portion 21 arranged in the axial middle portion. The inner diameter side engagement core portion 70 constituting the shaft body 69 is coated with the resin coating 27 over its entire axial length and entire circumference. The inner diameter side engagement portion 19 is composed of the inner diameter side engagement core portion 70 and the resin coating 27.

[0107] The inner diameter side engagement core portion 70 includes a non-engagement core portion 72 and first engagement core portions 71a and 71b arranged on both sides of the non-engagement core portion 72 in the axial direction. The first engagement core portions 71a and 71b are respectively composed of an outer tooth core portion 88 in which a plurality of tooth cores 73 are arranged in the circumferential direction. The plurality of tooth cores 73 are elongated in the axial direction and are arranged at equal intervals in the circumferential direction. The tooth thickness and tooth height of each of the plurality of tooth cores 73 are constant in the axial direction except for the chamfered portion 83 provided at the end portion on the far side relative to the non-engagement core portion 72.

[0108] In the first engagement cores 71a and 71b, the number, pitch, tooth thickness, tooth height and arrangement phase of the plurality of tooth cores 73 are the same in the first engagement core 71a arranged on one axial side and the first engagement core 71b arranged on the other axial side.

[0109] In this example, the axial dimension L of the first engagement core portion 71b on the other axial side is 71b The axial dimension L of the first engagement core portion 71a on the axial side is 71a Large (L 71b >L 71a ) and is greater than the effective length X (L 71a >X).

[0110] The non-engaging core portion 72 is disposed between the first engaging core portions 71a and 71b in the axial direction. The non-engaging core portion 72 is formed of a cylindrical surface whose outer diameter does not change in the axial direction. The non-engaging core portion 72 has an outer diameter smaller than the root diameter of the tooth core 73 constituting the first engaging core portions 71a and 71b.

[0111] The outer peripheral surface of the connection part 20 has a concavo-convex shape in the circumferential direction. Specifically, on the outer peripheral surface of the connection part 20, a plurality of external serrations 28 extending in the axial direction are arranged in the circumferential direction.

[0112] A torque transmission joint (not shown) is fixed relatively non-rotatably to the connection portion 20. Thus, the other axial end of the inner shaft 17 is connected to the output shaft 63 constituting the reaction force generating device 10 via the torque transmission joint.

[0113] The intermediate shaft portion 21 has a portion between the inner diameter side engagement portion 19 and the connection portion 20 in the axial direction. The intermediate shaft portion 21 has a cylindrical outer peripheral surface similar to the non-engaging core portion 72, and has the same cross-sectional shape, outer diameter, and surface properties as those of the non-engaging core portion 72.

[0114] The manufacturing method of the shaft body 69 is not particularly limited, and the shaft body 69 can be manufactured only by forging or only by cutting, or can be manufactured by appropriately combining forging and cutting. As for the non-engaging core portion 72 constituting the inner diameter side engaging core portion 70, it is not necessary to make the surface properties good, so when the shaft body 69 is manufactured by forging, excess material can also be left in the non-engaging core portion 72.

[0115] The resin coating 27 of the inner diameter side engagement portion 19 achieves a reduction in the sliding resistance of the inner diameter side engagement portion 19 during the telescopic operation of the steering shaft 11. Specifically, the entire axial length of the first engagement core portion 71a on one axial side and the entire axial length of the non-engagement core portion 72 are respectively coated with the resin coating 27, and the first engagement core portion 71b on the other axial side is coated with the resin coating 27 from the end on one axial side to the axial middle portion. The end on the other axial side of the first engagement core portion 71b on the other axial side is not covered by the resin coating 27 and is exposed.

[0116] The resin coating 27 includes two first engaging core covering portions 74a and 74b covering the first engaging core portions 71a and 71b, a non-engaging core covering portion 75 covering the non-engaging core portion 72, and two substantially annular side plate portions 76a and 76b.

[0117] In the first engagement core covering parts 74a, 74b, the first engagement core covering part 74a on one axial side covers the first engagement core 71a on one axial side over the entire axial length, and the first engagement core covering part 74b on the other axial side covers the range from the end of the first engagement core 71b on the other axial side to the axial middle part. The outer peripheral surface of the first engagement core covering parts 74a, 74b is composed of a concave-convex surface formed by alternately arranging concave parts and convex parts in the circumferential direction.

[0118] The outer peripheral surface of the non-engaging core covering portion 75 is a cylindrical surface whose outer diameter does not change in the axial direction. The outer diameter of the non-engaging core covering portion 75 is smaller than the outer diameter of the bottom surface of the recessed portion in the outer peripheral surface of the first engaging core covering portions 74a and 74b.

[0119] The side plates 76a and 76b connect the ends of the non-engaging core covering portion 75 on both axial sides to the ends of the first engaging core covering portions 74a and 74b on the proximal side relative to the non-engaging core covering portion 75. The outer peripheral surfaces of the side plates 76a and 76b are composed of concave-convex surfaces in which concave portions and convex portions are alternately arranged in the circumferential direction.

[0120] The end face on one axial side of the non-engaging core portion covering portion 75 and the side face on one axial side of the side plate portion 76a on one axial side abut against the end face on the other axial side of the plurality of tooth cores 73 constituting the first engaging core portion 71a on one axial side, and the end face on the other axial side of the non-engaging core portion covering portion 75 and the side face on the other axial side of the side plate portion 76b on the other axial side abut against the end face on one axial side of the plurality of tooth cores 73 constituting the first engaging core portion 71b on the other axial side. Thus, even when the resin coating 27 is formed by a method such as injection molding without using an adhesive for bonding the synthetic resin constituting the resin coating 27 to the metal material constituting the shaft body 69, relative displacement of the resin coating 27 in the axial direction with respect to the shaft body 69 can be prevented.

[0121] In order to improve the bonding strength between the shaft body 69 and the resin coating 27, micro-convex and concave portions can be provided on part or all of the inner diameter side snap-in core portion 70 of the shaft body 69 by shot peening, or adhesive can be applied to part or all of the inner diameter side snap-in core portion 70 of the shaft body 69.

[0122] The axial dimension L of the resin coating 27 is 27 The length (L) is approximately the same as three times the effective length X of each of the first engaging portions 22a and 22b. 27 ≈3X). In this example, the axial dimension L of the resin coating 27 is 27 It is about 150mm.

[0123] In this example, more specifically, the effective length X is the axial dimension of the plurality of external teeth 25 that mesh with the plurality of internal teeth 33 when torque is transmitted between the inner shaft 17 and the outer shaft 18. When the inner shaft 17 is relatively displaced in the axial direction with respect to the outer shaft 18, the tooth surfaces (circumferential side surfaces) of the portions of the plurality of external teeth 25 that mesh with the plurality of internal teeth 33 when torque is transmitted between the inner shaft 17 and the outer shaft 18 come into sliding contact with the tooth surfaces of the plurality of internal teeth 33. The axial dimension L of the first engagement core portion 71a is limited in such a manner that the axial dimension of the first engagement portion 22a on one axial side and the axial dimension of the non-engagement portion 23 become the effective length X. 71a and the axial dimension L of the non-engaging core portion 72 72 .

[0124] The axial dimension L of the first engagement core portion 71a on one axial side is 71a The effective length X is obtained by subtracting the axial dimension of the side plate portion 76a on the axial side of the resin coating 27 from the effective length X. 72 It is the sum of the effective length X and the axial thickness of the side plate portions 76a and 76b.

[0125] The resin coating 27 is made of a synthetic resin having a low friction coefficient with respect to the metal material constituting the outer shaft 18 , such as polyamide resin (PA), polytetrafluoroethylene resin (PTFE), or polyoxymethylene resin (POM).

[0126] like Figure 8 As shown in (A), the thickness of the resin coating 27 is substantially constant throughout the entire circumference and is sufficiently smaller than the tooth width and tooth height of the tooth core 73. Specifically, the thickness of the resin coating 27 is about 10 μm to 1000 μm. The resin coating 27 has a contour shape along the outer shape of the first engaging core portion 71a, 71b and the non-engaging core portion 72. Such a resin coating 27 can be formed, for example, by injection molding using a molding die.

[0127] In the case of implementing the present disclosure, the thickness of the resin coating 27 can also be varied in the circumferential direction. Figure 8 As shown in (B), the thickness of the portion of the resin coating 27 covering the tooth top surface of the tooth core 73 can be made smaller than the thickness of the portion covering the tooth bottom surface between two circumferentially adjacent tooth cores 73. Such a resin coating 27 can be formed by fluid impregnation.

[0128] The non-engaging core covering portion 75 constituting the resin coating 27 can be formed by, for example, performing cutting on the outer peripheral surface after molding synthetic resin around the shaft body 69. Alternatively, the cutting process can be omitted when the amount of heat shrinkage of the synthetic resin molded around the non-engaging core 72 is sufficiently greater than the amount of heat shrinkage of the synthetic resin molded around the first engaging cores 71a and 71b.

[0129] That is, since the thickness of the synthetic resin increases, the amount of thermal shrinkage increases. Therefore, even if the synthetic resin molded around the non-engaging core portion 72 is molded so that its outer diameter is the same as the outer diameter of the synthetic resin molded around the first engaging core portions 71a, 71b, the amount of thermal shrinkage of the synthetic resin molded around the non-engaging core portion 72 is greater than the amount of thermal shrinkage of the synthetic resin molded around the first engaging core portions 71a, 71b.

[0130] Outer Axis

[0131] The outer shaft 18 has a hollow cylindrical shape. The outer shaft 18 is arranged on one axial side of the inner shaft 17. The outer shaft 18 has a large diameter cylinder portion 29 in the range from the end portion on the other axial side to the axial middle portion, and has a small diameter cylinder portion 30 at the end portion on one axial side. The outer shaft 18 has an outer diameter side engaging portion 31 at the end portion on the other axial side of the inner circumferential surface of the large diameter cylinder portion 29. The steering wheel 2 is fixed to the end portion on one axial side of the outer shaft 18. In this example, the outer diameter side engaging portion 31 is equivalent to the engaging portion on the other side.

[0132] The outer diameter side engagement portion 31 has a second engagement portion 32 over the entire axial length. That is, the outer diameter side engagement portion 31 is composed only of the second engagement portion 32. The second engagement portion 32 is composed of an internal tooth portion 87 formed by arranging a plurality of internal teeth 33 in the circumferential direction. The plurality of internal teeth 33 are elongated in the axial direction and are arranged in the circumferential direction. The circumferential arrangement of the plurality of internal teeth 33 in this example is equal in pitch.

[0133] The tooth thickness and tooth height of each of the plurality of internal teeth 33 are constant in the axial direction except for the chamfered portion 34 provided at the axial end. The internal teeth 33 have a tip circle diameter larger than the outer diameter of the non-engaging portion 23 of the inner shaft 17 .

[0134] In this example, the second engagement portion constituting the outer diameter side engagement portion 31 is constituted by an internal spline portion. The plurality of internal teeth 33 are constituted by internal spline teeth.

[0135] The second engagement portion 32 engages with the first engagement portions 22a and 22b of the inner diameter side engagement portion 19 of the inner shaft 17 in a manner capable of transmitting torque and enabling relative displacement in the axial direction. Specifically, the plurality of internal teeth 33 constituting the second engagement portion 32 mesh with the plurality of external teeth 25 of the first engagement portions 22a and 22b. As a result, the outer shaft 18 and the steering wheel 2 move relative to the inner shaft 17 in the front-rear direction, thereby causing the steering shaft 11 to extend and retract.

[0136] The second engagement portion 32 does not engage with the non-engagement portion 23 of the inner diameter side engagement portion 19 provided on the inner shaft 17. Specifically, the tooth top surfaces of the plurality of internal teeth 33 face the outer peripheral surface of the non-engagement portion 23 via a gap.

[0137] In this example, the axial dimension of the portion of the plurality of internal teeth 33 separated from the chamfered portion 34, i.e., the effective length Y of the second engagement portion 32, is twice the effective length X of the first engagement portions 22a, 22b constituting the inner diameter side engagement portion 19 (2X). In this example, the value of "Y" is about 100 mm.

[0138] However, in the case where the chamfered portion 34 contributes to the torque transmission, the effective length Y becomes the entire axial length of the plurality of internal teeth 33 including the chamfered portion 34 .

[0139] When the total length of the steering shaft 11 of this example is changed, the spline engagement form of the inner diameter side engagement portion 19 and the outer diameter side engagement portion 31 is as follows: Fig. 9 (A)~ Fig. 9 Switch as shown in (D).

[0140] Fig. 9(A) shows a state in which the full length of the steering shaft 11 is stretched to the maximum. In this state, the plurality of external teeth 25 constituting the first engaging portion 22a on one axial side mesh with the plurality of internal teeth 33 constituting the half portion on the other axial side of the second engaging portion 32. In this state, the engagement length E of the plurality of external teeth 25 and the plurality of internal teeth 33 becomes the same length as the effective length X of the first engaging portion 22a.

[0141] Fig. 9 (B) shows that the total length of the steering shaft 11 is increased from Fig. 9 The state (A) of the steering shaft 11 is contracted by a stroke equal to X. Fig. 9 The state of (A) is Fig. 9 When the outer shaft 18 is contracted in the state (B), the plurality of external teeth 25 constituting the first engaging portion 22a on the axial side remain in mesh with the plurality of internal teeth 33 constituting the second engaging portion 32 and move toward the axial side. Furthermore, the non-engaging portion 23 is inserted radially inward of the end portion on the other axial side of the outer shaft 18. In this case, the engagement length E remains unchanged at X.

[0142] Fig. 9 (C) shows that the total length of the steering shaft 11 is increased from Fig. 9 The state (B) is further contracted by a stroke equal to X. If the total length of the steering shaft 11 is reduced from Fig. 9 The state of (B) is Fig. 9 When the plurality of external teeth 25 of the first engaging portion 22a constituting one axial side are contracted to the state (C), they extend toward one axial side from the plurality of internal teeth 33 constituting the second engaging portion 32, and at the same time, the plurality of external teeth 25 of the first engaging portion 22b constituting the other axial side begin to mesh with the plurality of internal teeth 33 constituting the second engaging portion 32.

[0143] In this state, the plurality of external teeth 25 of the first engagement portion 22a on one axial side and the external teeth 25 of the first engagement portion 22b on the other axial side are spline-engaged with the plurality of internal teeth 33 at the same time. The sum of the engagement lengths of the plurality of external teeth 25 and the plurality of internal teeth 33 constituting the first engagement portion 22a on one axial side and the engagement lengths of the plurality of external teeth 25 and the plurality of internal teeth 33 constituting the first engagement portion 22b on the other axial side is X. Therefore, when the total length of the steering shaft 11 is reduced from Fig. 9 The state of (B) is Fig. 9 During the contraction of the state (C), the engagement length E remains unchanged at X.

[0144] Fig. 9 (D) shows that the total length of the steering shaft 11 is Fig. 9 The state (C) is further contracted by a stroke equal to X, thereby reducing the total length of the steering shaft 11 to the maximum. Fig. 9 The state of (C) Fig. 9 The outer teeth 25 of the first engaging portion 22b on the other axial side remain in mesh with the inner teeth 33 of the second engaging portion 32 and move toward one axial side. Fig. 9 The state of (C) Fig. 9 Even when the state (D) is contracted, the engagement length E remains unchanged at X.

[0145] Even when the total length of the steering shaft 11 is changed, the engagement length E between the plurality of external teeth 25 and the plurality of internal teeth 33 can be kept constant. Therefore, when the sliding resistance when the engagement length is X is set to α, the relationship between the sliding resistance and the stroke amount is as follows: Fig.10 shown.

[0146] That is, in the steering shaft 11, since the engagement length E is constant regardless of the increase or decrease of the stroke amount, the sliding resistance is constant. Fig.10 The horizontal axis shows the stroke amount from the state where the full length of the steering shaft 11 is extended to the maximum. Fig.10 The vertical axis shows the magnitude of the sliding resistance. Also, the engagement length E is shown in parentheses next to the stroke amount.

[0147] Steering Column

[0148] The steering column 12 is configured to be telescopic in its entire length and is supported by a vehicle body (not shown). The steering column 12 includes a bracket 35 and a column body 36. The steering column 12 of this example has a two-stage telescopic structure in order to ensure a large telescopic stroke in the front-rear direction.

[0149] The bracket 35 is for supporting the column body 36 on the vehicle body, and includes a fixing bracket 37 fixed to the vehicle body and a displacement bracket 38 supported so as to be relatively displaceable in the front-rear direction with respect to the fixing bracket 37 .

[0150] The fixing bracket 37 includes a fixing plate portion 39 having a substantially rectangular flat plate shape and a fixing side support frame 40 having a substantially U-shaped shape. The fixing plate portion 39 is fixed to the vehicle body by a plurality of mounting bolts 41. The fixing side support frame 40 is provided at the front end of the fixing plate portion 39 and connects the ends of both sides of the fixing plate portion 39 in the width direction.

[0151] The displacement bracket 38 includes a displacement plate 42 arranged to overlap the lower surface of the fixed plate 39 and a substantially U-shaped displacement side support frame 43. The displacement plate 42 is supported by a linear guide 44 so as to be relatively displaceable in the front-rear direction with respect to the fixed plate 39.

[0152] The displacement side support frame 43 is provided at the rear end of the displacement plate portion 42, and connects the ends of both sides in the width direction of the displacement plate portion 42. A threaded shaft (not shown) of the tilt feed screw device 60 constituting the tilt actuator 15 is rotatably supported on the inner side surface of one of the pair of left and right support wall portions 45 constituting the displacement side support frame 43 with the axial direction directed in the up-down direction.

[0153] The column body 36 is generally cylindrical in shape and arranged with its axial direction facing the front-rear direction. The column body 36 includes an outer column 46 arranged in the middle of the front-rear direction, a lower inner column 47 fitted in the front side of the outer column 46, and an upper inner column 48 fitted in the rear side of the outer column 46.

[0154] The outer column 46 is supported so as to be movable in the up-down direction relative to the displacement bracket 38. The rear side portion of the outer column 46 is inserted into the inner side of the displacement side support frame 43 constituting the displacement bracket 38 in the front-to-back direction. A nut (not shown) of the tilt feed screw device 60 constituting the tilt actuator 15 is pivotally supported on the outer peripheral surface of the rear side portion of the outer column 46. The outer column 46 has a slit (not shown) extending in the front-to-back direction in the middle portion of the lower surface.

[0155] The lower inner column 47 is embedded in the front side portion of the outer column 46 so as to be relatively displaceable in the front-rear direction. The front end of the lower inner column 47 is supported and fixed to the fixed bracket 37 via the gear box 61. In addition, the inner shaft 17 is rotatably supported on the inner side of the lower inner column 47 via the rolling bearing 16.

[0156] The upper inner column 48 is fitted inside the rear portion of the outer column 46 so as to be relatively displaceable in the front-rear direction. The outer shaft 18 is rotatably supported inside the upper inner column 48 via the rolling bearing 16 .

[0157] 〈Lower extension actuator〉

[0158] The lower telescopic actuator 13 is arranged to bridge between the fixed bracket 37 and the displacement bracket 38, and displaces the displacement bracket 38 in the front-rear direction relative to the fixed bracket 37. As a result, the outer column 46 and the lower inner column 47 are relatively displaced in the front-rear direction, and the column body 36 is telescoped.

[0159] The lower telescopic actuator 13 includes a lower telescopic motor 49 and a lower feed screw device 50 .

[0160] The lower telescopic motor 49 is supported and fixed to a side surface in the width direction of the fixed-side support frame 40 constituting the fixed bracket 37 so that a motor output shaft (not shown) is oriented in the up-down direction.

[0161] like Figure 2As shown, the lower feed screw device 50 includes a lower threaded shaft 51 and a lower nut 52. The lower threaded shaft 51 is arranged so that the axial direction faces the front-rear direction, and is driven to rotate by the lower telescopic motor 49 via a reduction mechanism such as a worm reducer not shown. The lower threaded shaft 51 is supported so as to be rotatable only relative to the fixed bracket 37. The lower nut 52 is threadedly coupled to the lower threaded shaft 51 and is supported on the side surface of the displacement bracket 38 in the width direction.

[0162] That is, the lower telescopic actuator 13 rotationally drives the lower telescopic motor 49 to displace the lower nut 52 in the axial direction of the lower threaded shaft 51 , thereby displacing the outer column 46 relative to the lower inner column 47 in the front-rear direction.

[0163] 〈Upper extension actuator〉

[0164] The upper telescopic actuator 14 is disposed so as to be bridged between the outer column 46 and the upper inner column 48, and displaces the upper inner column 48 in the front-rear direction relative to the outer column 46. Thus, the column body 36 is telescoped.

[0165] The upper telescopic actuator 14 includes an upper telescopic motor 53 and an upper feed screw device 54 .

[0166] The upper telescopic motor 53 is supported below the front end portion of the outer column 46 so that a motor output shaft (not shown) faces in the width direction.

[0167] The upper feed screw device 54 includes an upper threaded shaft 55 and an upper nut 56. The upper threaded shaft 55 is arranged so that the axial direction faces the front-rear direction, and is driven to rotate by the upper telescopic motor 53 via a reduction mechanism such as a worm reducer (not shown). The upper threaded shaft 55 is supported so as to be rotatable only relative to the outer column 46. The upper nut 56 is threadedly coupled to the upper threaded shaft 55 and is supported on the lower surface of the upper inner column 48 via a connector component 57.

[0168] The connector component 57 is arranged inside the slit provided in the outer column 46 and fixed to the lower surface of the upper inner column 48. That is, the upper telescopic actuator 14 rotates and drives the upper telescopic motor 53 to displace the upper nut 56 along the axial direction of the upper threaded shaft 55, thereby displacing the upper inner column 48 relative to the outer column 46 in the front-rear direction.

[0169] 〈Tilt Actuator〉

[0170] The tilt actuator 15 is arranged so as to be bridged between the displacement side support frame 43 and the outer column 46 constituting the displacement bracket 38, and displaces the outer column 46 in the vertical direction relative to the displacement bracket 38. In addition, the reaction force generating device 10 connected to the front side of the position adjustment device 9 is supported by a pair of pivot support bolts 58 arranged in the width direction so as to be rotatable relative to the fixed side support frame 40. Thus, the column body 36 can be swung in the vertical direction relative to the bracket 35 with the pivot support bolts 58 as the center.

[0171] The tilt actuator 15 includes a tilt motor 59 and a tilt feed screw device 60 .

[0172] The tilt motor 59 is fixed to one support wall portion 45 constituting the displacement-side support frame 43 so that a motor output shaft (not shown) faces in the front-rear direction.

[0173] The tilt feed screw device 60 includes a tilt threaded shaft and a tilt nut (not shown). The tilt threaded shaft is arranged so that the axial direction faces the up-down direction, and is driven to rotate by the tilt motor 59 via a reduction mechanism such as a worm reducer (not shown). The tilt threaded shaft is supported so as to be rotatable only relative to one support wall portion 45. The tilt nut is threadedly coupled to the tilt threaded shaft and is pivotally supported on the side surface of the outer column 46 in the width direction.

[0174] That is, the tilt actuator 15 rotationally drives the tilt motor 59 to displace the tilt nut in the axial direction of the tilt threaded shaft, thereby displacing the outer column 46 relative to the displacement bracket 38 in the up-down direction.

[0175] 《How to adjust the position of the steering wheel》

[0176] In order to adjust the front-rear position of the steering wheel 2 by using the position adjustment device 9 of this example, the lower telescopic actuator 13 and / or the upper telescopic actuator 14 are driven. When the lower telescopic actuator 13 is driven, the displacement bracket 38 is relatively displaced in the front-rear direction relative to the fixed bracket 37, and the outer column 46 is relatively displaced in the front-rear direction relative to the lower inner column 47. When the upper telescopic actuator 14 is driven, the upper inner column 48 is relatively displaced in the front-rear direction relative to the outer column 46.

[0177] Thus, the full length of the steering column 12 is extended and retracted, and the full length of the steering shaft 11 is extended and retracted, thereby adjusting the front-rear position of the steering wheel 2. After the front-rear position of the steering wheel 2 is adjusted to a desired position, the driving of the lower telescopic actuator 13 and / or the upper telescopic actuator 14 is stopped.

[0178] In order to adjust the vertical position of the steering wheel 2 using the position adjustment device 9 of this example, the tilt actuator 15 is driven to displace the rear portion of the outer column 46 in the vertical direction relative to the displacement bracket 38. As a result, the steering shaft 11 rotatably supported on the inner side of the column body 36 swings to adjust the vertical position of the steering wheel 2. After the vertical position of the steering wheel 2 is adjusted to the desired position, the driving of the tilt actuator 15 is stopped.

[0179] The front-rear position and the up-down position of the steering wheel 2 can be adjusted simultaneously or independently (one after the other in time).

[0180] In order to utilize the position adjustment device 9 of this example, the steering wheel 2 is largely retracted forward during automatic driving and stored on the instrument panel or arranged away from the driver, and the lower telescopic actuator 13 and the upper telescopic actuator 14 are driven respectively. As a result, the displacement bracket 38 is relatively displaced forward relative to the fixed bracket 37, the outer column 46 is relatively displaced forward relative to the lower inner column 47, and the upper inner column 48 is relatively displaced forward relative to the outer column 46.

[0181] The entire length of the steering column 12 is retracted, and the entire length of the steering shaft 11 is retracted to Fig. 9 The state (D) is set so that the steering wheel 2 is largely retracted forward. After the steering wheel 2 is largely retracted forward, the driving of each of the lower telescopic actuator 13 and the upper telescopic actuator 14 is stopped.

[0182] 〈Reaction force generating device〉

[0183] The reaction force generating device 10 is arranged in front of the position adjusting device 9 and fixed relative to the position adjusting device 9. The reaction force generating device 10 is controlled by the control device 6 to apply a steering reaction force of magnitude and direction corresponding to the steering angle of the steering wheel 2, the vehicle speed and other driving conditions to the steering wheel 2.

[0184] The reaction force generating device 10 includes a gear box 61 , a reaction force applying motor 62 , a worm speed reducer (not shown), and an output shaft 63 .

[0185] The gear box 61 is fixed to the front end of the lower inner column 47 constituting the position adjusting device 9. The output shaft 63 is supported inside the gear box 61 so as to be rotatable.

[0186] The reaction force applying motor 62 is supported and fixed to the gear box 61. The rotation of the reaction force applying motor 62 is transmitted to the steering shaft 11 via the worm reducer and the output shaft 63.

[0187] The worm reducer includes a worm wheel externally fitted and fixed to the output shaft 63 , and a worm fixed to the front end portion of the motor output shaft of the reaction force applying motor 62 .

[0188] The output shaft 63 is arranged so that the axial direction faces the front-rear direction, and is rotatably supported on the inner side of the gear box 61. The output shaft 63 has a structure in which the lower output shaft and the upper output shaft, which are arranged coaxially with each other, are connected to each other via a torsion bar. A torque sensor for measuring the steering torque input from the driver to the steering wheel 2 is arranged around the upper output shaft. The rear end of the upper output shaft is connected to the front end of the inner shaft 17 constituting the steering shaft 11 via a torque transmission joint.

[0189] In order to apply a steering reaction force to the steering wheel 2 by the reaction force generating device 10, the reaction force applying motor 62 is driven by the control device 6 based on various signals indicating driving conditions such as steering torque, steering angle, and vehicle speed. The rotation of the reaction force applying motor 62 is transmitted to the output shaft 63 via the worm reducer, and is applied to the steering wheel 2 as a steering reaction force via the steering shaft 11.

[0190] According to the steering shaft 11 of the steering device 1 of this example, especially in a structure that increases the stroke of the steering shaft 11, when the total length of the steering shaft 11 is changed, it is also possible to suppress the sliding resistance from changing with the change of the engagement length of the inner shaft 17 and the outer shaft 18.

[0191] In this example, the inner diameter side engagement portion 19 of the inner shaft 17 includes the first engagement portions 22a and 22b having an effective length X and the first engagement portions 22a and 22b having the same axial dimension L as the effective length X. 23 The inner diameter side engagement portion 19 is configured by arranging two first engagement portions 22a and 22b on both sides of the non-engaging portion 23. Moreover, the effective length Y of the second engagement portion 32 of the outer diameter side engagement portion 31 of the outer shaft 18 is equal to the effective length X and the axial dimension L of the non-engaging portion 23. 23 The sum is set to a length (2X) that is twice the effective length X.

[0192] Therefore, when the total length of the steering shaft 11 is changed, Fig. 9 (A)~ Fig. 9 As shown in (D), the engagement length E of the plurality of external teeth 25 and the plurality of internal teeth 33 remains constant. Therefore, when the total length of the steering shaft 11 is changed, the magnitude of the sliding resistance of the steering shaft 11 can be kept constant. As a result, the steering shaft 11 of this example has a long stroke, and when the lower telescopic actuator 13 and the upper telescopic actuator 14 are driven to change the total length, the change in the driving sound is suppressed, thereby preventing the driver and passengers from feeling uncomfortable.

[0193] Furthermore, when the effective length of the plurality of external teeth 25 is set to X and the effective length of the plurality of internal teeth 33 is set to 2X, the telescopic stroke of the steering shaft 11 can be ensured to be 3X. Therefore, the axial dimensions of the plurality of external teeth 25 and the plurality of internal teeth 33 do not need to be too large. Therefore, since the bending generated during the manufacture of the inner shaft 17 and the outer shaft 18 can be suppressed, the productivity of the steering shaft 11 can be ensured.

[0194] In this example, in the inner shaft 17, the end portion on one axial side of the shaft body 69 is coated with the resin coating 27, and the inner diameter side engagement portion 19 is provided with the resin coating 27. However, when implementing the present disclosure, the resin coating may be omitted.

[0195] [Second example]

[0196] use Fig.11 A second example of the embodiment of the present disclosure will be described.

[0197] In this example, the axial dimension L of the first engagement core portion 71a on the axial side of the inner diameter side engagement core portion 70 provided in the shaft body 69 is 71a The axial dimension L of the first engagement core portion 71b on the other axial side is 71b About the same.

[0198] The resin coating 27 covers the range from the axial end of the first engagement core 71a to the axial end of the intermediate shaft 21. That is, the first engagement core 71b on the other axial side is covered by the first engagement core covering portion 74b over the entire axial length.

[0199] In this example, when forming the resin coating 27, first, the shaft body 69 is placed in the mold 77. The cavity 78 of the mold 77 has an inner surface shape corresponding to the outer surface shape of the resin coating 27 to be formed, that is, an inner surface shape that is opposite in concave and convex to the outer surface shape of the resin coating 27. Next, a molten synthetic resin is fed into the cavity 78 from a gate 79 arranged radially outside the end portion on one axial side of the intermediate shaft portion 21, and the molten synthetic resin is cooled and solidified, thereby forming the resin coating 27.

[0200] According to this example, after the synthetic resin is injection molded around the shaft body 69, it is not necessary to cut the outer peripheral surface of the portion that becomes the non-engaging portion 23, so that the steering shaft 11 is easily manufactured. Compared with the structure of the first example, it is easy to restrict the axial dimension of the first engaging portion 22b on the other axial side to the effective length X with high accuracy.

[0201] Fig.12 A modification of the second example is shown. In this modification, a fillet portion 80 having an arc-shaped cross-sectional shape is provided at a connection portion between the outer peripheral surface of the side plate portions 76a and 76b and the axial side surface.

[0202] According to this modification, the axial ends of the outer peripheral surfaces of the side plates 76 a and 76 b are less likely to get caught on the inner peripheral surface of the outer shaft 18 , thereby preventing the axial relative displacement of the inner shaft 17 relative to the outer shaft 18 from being hindered.

[0203] The structure and effects of other parts of the second example are the same as those of the first example.

[0204] [Third example]

[0205] use Figure 13 to Figure 15 (B) A third example of the embodiment of the present disclosure is described.

[0206] In this example, the inner diameter side engagement portion 19 has a plurality of notched recessed portions 81 at the circumferential positions of the end portion on the axial side of the outer peripheral surface. Specifically, the first engagement portion 22a on the axial side has a notched recessed portion 81 at four circumferential positions of the end portion on the axial side of the outer peripheral surface. Each notched recessed portion 81 has a semicircular cross-sectional shape and opens at the outer peripheral surface of the first engagement portion 22a on the axial side and the end surface on the axial side.

[0207] In this example, each notch recess 81 is formed between two circumferentially adjacent external teeth 25. Grease is retained in each notch recess 81. Thus, the lubrication state of the inner diameter side engaging portion 19 and the outer diameter side engaging portion 31 can be well maintained for a long time, and the resistance when the inner shaft 17 is relatively displaced in the axial direction with respect to the outer shaft 18 can be suppressed to be small.

[0208] In this example, when the resin coating 27 is formed, the shaft body 69 is placed in the mold. Fig.14 As shown, a positioning pin 82 is inserted into a portion of the portion between the plurality of tooth cores 73 constituting the first engaging core portion 71a on one axial side, thereby realizing the circumferential positioning of the shaft body 69 relative to the mold. Next, molten synthetic resin is injected into the mold under pressure. The synthetic resin is cooled and solidified, and the completed inner shaft 17 is taken out of the mold. The synthetic resin of the portion where the positioning pin 82 is arranged around the first engaging core portion 71a on one axial side is extremely thin compared to other portions, and a notch recess 81 is formed in this portion.

[0209] In this example, the thickness of some of the plurality of external teeth 25 constituting the first engaging portions 22a and 22b is smaller than the thickness of the remaining external teeth 25. Specifically, the thickness of the synthetic resin covering some of the plurality of tooth cores 73 is smaller than the thickness of the synthetic resin covering the remaining tooth cores 73.

[0210] When torque is transmitted between the inner shaft 17 and the outer shaft 18, the outer teeth 25 having a smaller tooth thickness mesh with the inner teeth 33 constituting the outer diameter side engagement portion 31, but when the inner shaft 17 is relatively displaced in the axial direction relative to the outer shaft 18, the tooth surfaces thereof do not slide in contact with the tooth surfaces of the inner teeth 33. Therefore, the resistance when the inner shaft 17 is relatively displaced in the axial direction relative to the outer shaft 18 can be suppressed to be small.

[0211] In this example, the notched recessed portion 81 is formed between the circumferentially adjacent external teeth 25 having a smaller tooth thickness. Therefore, the notched recessed portion 81 can minimize the effect of the resistance generated when the inner shaft 17 is displaced relative to the outer shaft 18 in the axial direction.

[0212] The structure and effects of other parts of the third example are the same as those of the first example.

[0213] [Fourth example]

[0214] use Fig.16 A fourth example of the embodiment of the present disclosure will be described.

[0215] In this example, the structure of the non-engaging core portion 72 a constituting the inner diameter side engaging core portion 70 a of the shaft body 69 a constituting the inner shaft 17 is changed from the structure of the first example.

[0216] In this example, only one annular groove 64 is formed in the axial middle portion of the outer peripheral surface of the non-engaging core portion 72a of the shaft body 69a. The outer peripheral surface of the non-engaging core portion 72a is covered with the resin coating 27, so that the synthetic resin constituting the resin coating 27 enters the inner side of the annular groove 64, and the resin coating 27 is axially engaged with the annular groove 64. That is, the annular groove 64 constitutes an anti-slip portion that inhibits the relative movement of the resin coating 27 with respect to the shaft body 69a in the axial direction.

[0217] In this example, the annular groove 64 is formed on the outer peripheral surface of the shaft body 69a, so that the relative displacement of the resin coating 27 in the axial direction with respect to the inner diameter side engagement core 70a can be suppressed. In other words, the holding force of the resin coating 27 can be improved. In addition, the outer diameter of the portion of the resin coating 27 covering the annular groove 64 can be the same as the outer diameter of the portion covering the portion of the shaft body 69a separated from the annular groove 64, and can also be smaller than the outer diameter of the portion covering the portion of the shaft body 69a separated from the annular groove 64 by an amount corresponding to twice the radial depth of the annular groove 64.

[0218] Fig.17 (A)~ Fig.17 (D) shows four variations of the fourth example.

[0219] exist Fig.17In the first modification shown in (A), a plurality of (four in the illustrated example) annular grooves 64a are formed on the outer peripheral surface of the non-engaging core portion 72a. The plurality of annular grooves 64a are arranged separately in the axial direction. The synthetic resin constituting the resin coating 27 is allowed to enter the inner side of each annular groove 64a, so that the resin coating 27 and the annular groove 64a are engaged in the axial direction. That is, in the first modification, the plurality of annular grooves 64a respectively constitute the anti-slip portion. In the first modification, the holding force of the resin coating 27 can be improved compared with the fourth example.

[0220] exist Fig.17 In the second modification shown in (B), a spiral groove 65 is formed on the outer peripheral surface of the non-engaging core portion 72a. The synthetic resin constituting the resin coating 27 is allowed to enter the inner side of the spiral groove 65, so that the resin coating 27 is engaged with the spiral groove 65. That is, in the second modification, the spiral groove 65 constitutes an anti-slip portion. According to the second modification, since the spiral groove 65 can be processed by clamping at one time, the productivity of the inner shaft 17 can be improved.

[0221] exist Fig.17 In the third modification shown in (C), a knurled groove 66 is formed on the outer peripheral surface of the non-engaging core portion 72a. The synthetic resin constituting the resin coating 27 is allowed to enter the inner side of the knurled groove 66, so that the resin coating 27 is engaged with the knurled groove 66. That is, in the third modification, the knurled groove 66 constitutes an anti-slip portion. According to the third modification, the holding force of the resin coating 27 can be improved.

[0222] exist Fig.17 In the fourth modification shown in (D), a plurality of recesses 67 are formed on the outer peripheral surface of the non-engaging core portion 72a. The plurality of recesses 67 are separated and arranged in a plurality of rows in the axial direction, and are arranged at equal intervals in the circumferential direction in each row. The synthetic resin constituting the resin coating 27 is allowed to enter the inner side of each recess 67, so that the resin coating 27 is engaged with the recess 67. In the fourth modification, the plurality of recesses 67 respectively constitute an anti-slip portion. According to the fourth modification, the holding force of the resin coating 27 can be improved.

[0223] The other structures and effects of the fourth example are the same as those of the first example.

[0224] [Fifth example]

[0225] use Fig.18 A fifth example of the embodiment of the present disclosure will be described.

[0226] In this example, the first engagement portions 22a and 22b constituting the inner diameter side engagement portion 19 each have a chamfered portion 26a at the end portion proximal to the non-engagement portion 23. The chamfering angle of the chamfered portion 26a is preferably 45 degrees or less, and is 30 degrees in the illustrated example.

[0227] The second engagement portion 32 has chamfered portions 34 at both ends in the axial direction. The chamfering angle of the chamfered portion 34 is preferably 45 degrees or less, and is 30 degrees in the example shown in the figure.

[0228] In this example, even when bending deformation occurs in either the inner shaft 17 or the outer shaft 18 , the axial ends of the first engagement portions 22 a and 22 b are prevented from rising above the axial end of the second engagement portion 32 .

[0229] That is, a chamfered portion 34 is provided at the end portion on one axial side of the second engaging portion 32, and a chamfered portion 26a is provided at the end portion on the other axial side of the first engaging portion 22a, so that when the outer shaft 18 is moved axially relative to the inner shaft 17, the end portion on the other axial side of the first engaging portion 22a can be prevented from exceeding the end portion on one axial side of the second engaging portion 32.

[0230] Furthermore, since a chamfered portion 34 is provided at the end portion on the other axial side of the second engaging portion 32, and a chamfered portion 26a is provided at the end portion on one axial side of the first engaging portion 22b, when the outer shaft 18 is moved relative to the inner shaft 17 to the other axial side, the end portion on one axial side of the first engaging portion 22b can be prevented from exceeding the end portion on the other axial side of the second engaging portion 32.

[0231] In this example, since the chamfered portion 26a is arranged at the end of each of the first engagement portions 22a and 22b on the proximal side relative to the non-engagement portion 23, the chamfered portion is arranged at the portions of the plurality of tooth cores 73 adjacent to both axial sides of the non-engagement core portion 72. The chamfered portion can also be continuous with the anti-slip portion formed on the outer peripheral surface of the non-engagement core portion 72.

[0232] In the present disclosure, the chamfered portions 34 may be formed only at the ends of the second engagement portion 32 on both axial sides, and the two chamfered portions 26a arranged at the ends of the first engagement portions 22a and 22b proximal to the non-engaging portion 23 may be omitted.

[0233] The other structures and effects of the fifth example are the same as those of the first example.

[0234] [Sixth example]

[0235] use Fig.19 A sixth example of the embodiment of the present disclosure will be described.

[0236] In this example, the outer diameter side engaging portion 31a constituting the outer shaft 18a is equivalent to the engaging portion of one side. The outer diameter side engaging portion 31a has a stepped shape, and has a non-engaging portion 68 in the axial middle portion that is not engaged with the inner diameter side engaging portion 19a of the inner shaft 17a, which is equivalent to the engaging member of the other side. The first engaging portions 84a and 84b, which are equivalent to two engageable portions, are arranged on both sides of the non-engaging portion 68. The first engaging portions 84a and 84b have an effective length X respectively. The non-engaging portion 68 has an axial dimension with a length equal to the effective length X.

[0237] That is, the outer diameter side engagement portion 31a includes one non-engaging portion 68 and two first engagement portions 84a and 84b. In the outer diameter side engagement portion 31a, the first engagement portion 84a, the non-engaging portion 68, and the first engagement portion 84b are arranged in this order in the axial direction.

[0238] The first engaging portions 84a and 84b are each composed of an internal tooth portion 87a in which a plurality of internal teeth 33a are arranged in the circumferential direction. The plurality of internal teeth 33a are elongated in the axial direction and are arranged at equal intervals in the circumferential direction. The tooth thickness and tooth height of each of the plurality of internal teeth 33a are constant in the axial direction except for the chamfered portion 34 provided at the end in the axial direction.

[0239] Of the first engagement portions 84a and 84b, the first engagement portion 84a disposed on the other axial side and the first engagement portion 84b disposed on one axial side have the same number, pitch, tooth thickness, and tooth height of the plurality of internal teeth 33a.

[0240] The first engagement portions 84a and 84b have the same effective length X. Specifically, the effective length X is the axial dimension of the portion separated from the chamfered portion 34 among the plurality of internal teeth 33a constituting each of the first engagement portions 84a and 84b.

[0241] The non-engaging portion 68 is disposed between the first engaging portions 84a and 84b in the axial direction. The non-engaging portion 68 has a cylindrical inner peripheral surface. The non-engaging portion 68 has an inner diameter larger than the root diameter of the plurality of internal teeth 33a constituting the first engaging portions 84a and 84b.

[0242] The non-engaging portion 68 has an axial dimension L which is the same as the effective length X of the first engaging portions 84a and 84b. 68 (L 68 = effective length X).

[0243] In contrast, the inner diameter side engaging portion 19a of this example has a second engaging portion 85 corresponding to the engageable portion over the entire axial length. That is, the inner diameter side engaging portion 19a is composed only of the second engaging portion 85. The second engaging portion 85 is composed of an external tooth portion 86a formed by arranging a plurality of external teeth 25a in the circumferential direction. The plurality of external teeth 25a are elongated in the axial direction and are arranged at equal intervals in the circumferential direction. The tooth thickness and tooth height of each of the plurality of external teeth 25a are constant in the axial direction, except for the chamfered portion 26 provided at the end portion in the axial direction. The plurality of external teeth 25a have a tooth top circle diameter that is smaller than the inner diameter of the non-engaging portion 68 of the outer shaft 18a.

[0244] The inner diameter side engagement portion 19a is provided with a resin coating 27. Specifically, the second engagement portion 85 is coated with the resin coating 27 over the entire length thereof.

[0245] The second engagement portion 85 engages with the first engagement portions 84a and 84b of the outer diameter side engagement portion 31a of the outer shaft 18a. Specifically, the plurality of external teeth 25a constituting the second engagement portion 85 engage with the plurality of internal teeth 33a of the first engagement portions 84a and 84b in a manner capable of transmitting torque and performing relative displacement in the axial direction. As a result, the outer shaft 18a and the steering wheel 2 move relative to the inner shaft 17a in the front-rear direction, thereby causing the steering shaft 11a to expand and contract.

[0246] The second engagement portion 85 does not engage with the non-engagement portion 68 of the outer diameter side engagement portion 31 a included in the outer shaft 18 a.

[0247] In this example, the axial dimension of the portion of the plurality of external teeth 25a covered by the resin coating 27, i.e., the effective length Y of the second engagement portion 85, is twice the effective length X of each of the first engagement portions 84a and 84b constituting the outer diameter side engagement portion 31a (2X). In this example, the value of "Y" is about 100 mm. In this example, the axial dimension L of the resin coating 27 is about 100 mm. 27 The length (L) is substantially the same as twice the effective length X of each of the first engaging portions 84a and 84b (2X). 27 ≈2X).

[0248] In the case of the steering shaft 11a of this example, even when the total length is changed, the engagement length E between the plurality of external teeth 25a and the plurality of internal teeth 33a can be kept constant. Therefore, even when the total length of the steering shaft 11a is changed, the sliding resistance can be kept constant. In addition, in this example, since the range (axial dimension L) of forming the resin coating 27 can be shortened compared to the structure of the first example, 27 ), so the manufacturing cost of the steering shaft 11a can be suppressed.

[0249] The other structures and effects of the sixth example are the same as those of the first example.

[0250] The embodiments of the present disclosure are described above, but the present disclosure is not limited thereto and can be appropriately modified within the scope of the technical concept of the invention. In addition, the structures of the first to sixth embodiments of the present disclosure and their modified embodiments can be appropriately combined and implemented as long as no contradiction occurs.

[0251] The present disclosure is not limited to an electric steering device that electrically adjusts the front-rear position of a steering wheel, but can also be applied to a manual steering device that manually adjusts the front-rear position of a steering wheel. Furthermore, the present disclosure is not limited to a steer-by-wire (linkless) steering device, but can also be applied to other types of steering devices.

[0252] Explanation of symbols

[0253] 1—steering device, 2—steering wheel, 3—steering control unit, 4—steering control wheel, 5—wheel steering unit, 6—control device, 7—wheel steering actuator, 8—steering tie rod, 9—position adjustment device, 10—reaction force generating device, 11, 11a—steering shaft, 12—steering column, 13—lower telescopic actuator, 14—upper telescopic actuator, 15—tilt actuator, 16—rolling bearing, 17, 17a—inner shaft, 18, 18a—outer shaft, 19, 19a—inner diameter side engaging portion, 20—connecting portion, 21—intermediate shaft portion, 22a, 22b—first engaging portion, 23—non-engaging portion, 25, 25a—outer teeth, 26, 26a—chamfered portion, 27—resin coating, 28—external serrations, 29—large diameter cylinder portion, 30—small diameter cylinder portion, 31, 31a—outer diameter side engaging portion, 32—second engaging portion, 33, 33a—internal teeth, 34—chamfered portion, 35—bracket, 36—column body, 37—fixed bracket, 38—displacement bracket, 39—fixed plate portion, 40—fixed side support frame, 41—mounting bolt, 42—displacement plate portion, 43—displacement side support frame, 44—linear guide, 45—support wall portion, 46—outer column, 47—lower inner column, 48—upper inner column, 49—lower telescopic motor, 50—lower feed screw device, 51—lower Threaded shaft, 52—lower nut, 53—upper telescopic motor, 54—upper feed screw device, 55—upper threaded shaft, 56—upper nut, 57—connector component, 58—pivot support bolt, 59—tilt motor, 60—tilt feed screw device, 61—gear box, 62—reaction force imparting motor, 63—output shaft, 64, 64a—annular groove, 65—spiral groove, 66—knurled groove, 67—recess, 68—non-engaging portion, 69, 69a—shaft body, 70a—inner diameter side engaging core, 71a, 71b—first engaging core, 72, 72a—non-engaging core, 73—tooth core, 74a, 74b—first Engaging core covering portion, 75—non-engaging core covering portion, 76a, 76b—side plate portion, 77—mold, 78—cavity, 79—gate, 80—rounded corner portion, 81—notched recess, 82—locating pin, 83—chamfered portion, 84a, 84b—first engaging portion, 85—second engaging portion, 86, 86a—external tooth portion, 87, 87a—internal tooth portion, 88—external tooth core portion, 89—internal tooth core portion, 100—steering shaft, 101, 101a—inner shaft, 102, 102a—outer shaft, 103—external spline teeth, 104—resin coating, 105—internal spline teeth, 106, 106a—external spline portion, 107, 107a—inner spline portion.

Claims

1. A steering shaft, characterized in that: have: an inner shaft having an inner diameter side engaging portion at an end portion on one axial side of an outer peripheral surface; and The outer shaft has an outer diameter side engagement portion at the end portion on the other axial side of the inner peripheral surface, and the outer diameter side engagement portion engages with the inner diameter side engagement portion in a manner capable of transmitting torque and performing relative axial displacement. The engagement portion of either the inner diameter side engagement portion or the outer diameter side engagement portion has at least one non-engaging portion in the axial middle portion that does not engage with the engagement portion of the other of the inner diameter side engagement portion or the outer diameter side engagement portion. The engageable portions of the engaging portion of one of the above-mentioned parts, which are arranged on both axial sides of the above-mentioned non-engaging portion, respectively have an effective length X, the above-mentioned non-engaging portion has an axial dimension with a length equal to the above-mentioned effective length X, and the engaging portion of the other of the above-mentioned parts has an effective length Y which is twice the length of the above-mentioned effective length X.

2. The steering shaft according to claim 1, characterized in that: The inner diameter side engagement portion is constituted by the one engagement portion, and the outer diameter side engagement portion is constituted by the other engagement portion. The engageable portion constituting the inner diameter side engaging portion is constituted by an external tooth portion formed by a plurality of external teeth, and the outer diameter side engaging portion is constituted by an internal tooth portion formed by a plurality of internal teeth, The effective length X is an axial dimension of a portion of the plurality of external teeth that engages with the plurality of internal teeth.

3. The steering shaft according to claim 2, characterized in that: The non-engaging portion is formed of a cylindrical surface having an outer diameter that is smaller than a root diameter of the plurality of external teeth.

4. The steering shaft according to claim 2 or 3, characterized in that: The inner shaft includes a shaft body and the inner diameter side engagement portion provided on an outer peripheral surface, and the inner diameter side engagement portion includes a resin coating covering an outer peripheral surface of an end portion on one axial direction side of the shaft body.

5. The steering shaft according to claim 4, characterized in that: The inner diameter side engagement portion includes an anti-slip portion that suppresses relative movement of the resin coating layer with respect to the shaft body in the axial direction.

6. The steering shaft according to claim 1, characterized in that: The outer diameter side engagement portion is constituted by the one engagement portion, and the inner diameter side engagement portion is constituted by the other engagement portion. The engageable portion constituting the outer diameter side engaging portion is constituted by an inner tooth portion formed by a plurality of inner teeth, and the inner diameter side engaging portion is constituted by an outer tooth portion formed by a plurality of outer teeth, The effective length X is the axial dimension of a portion of the plurality of internal teeth that engages with the plurality of external teeth.

7. The steering shaft according to claim 2 or 6, characterized in that: The external teeth portion of the inner diameter side engagement portion is composed of an external spline portion, and the plurality of external teeth are composed of external spline teeth.

8. The steering shaft according to claim 1, characterized in that: The number of the non-engaging portion is one, and the effective length X is greater than or equal to 30 mm.

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