Power transmission mechanism and steering column device

Abstract

The present invention provides a power transmission mechanism and steering column device that can suppress play in the threaded portion between the male screw shaft member and the female screw member with a simpler configuration. [Solution] The power transmission mechanism 30 includes a screw shaft 33 rotatably mounted on the outer column 5 and a drive member 35 mounted on the inner column 7 into which the screw shaft 33 is screwed. The rotation of the screw shaft 33 causes the screw shaft 33 and the drive member 35 to move relative to each other, causing the outer column 5 and the inner column 7 to move relative to each other. The screw shaft 33 and the drive member 35 each have a multi-start screw. In the multi-start screw provided on the drive member 35, the threading start position of the second female thread portion N1 is shifted circumferentially by an angle α from an angle An obtained by dividing 360 degrees by the number of threads in the multi-start screw, relative to the threading start position of the first female thread portion N1 adjacent in the circumferential direction.

Description

Technical Field

[0001] The present invention relates to a power transmission mechanism and a steering column device.

Background Art

[0002] There is known a steering column device provided with a tilt mechanism that rotatably supports a steering shaft by a jacket portion and swings the jacket portion in the vertical direction (Patent Document 1). In the tilt mechanism, a male screw shaft member is rotated by an electric motor, and a female screw member screwed onto the male screw shaft member moves axially together with a movable side casing. As a result, the jacket portion swings in the vertical direction.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] A clearance (backlash) for sliding is required at the screwed portion between the male screw shaft member and the female screw member, and this clearance causes play in the steering shaft. Therefore, in the conventional steering column device described above, in order to suppress play, two nuts screwed onto the male screw shaft member, a wedge member that presses the two nuts in the axial direction of the male screw shaft member, a screw member and a double nut for preventing the wedge member from coming out of the movable side casing are provided. Therefore, the conventional steering column device tends to have a large number of parts, a complicated structure, and a high manufacturing cost.

[0005] The present invention has been made in view of the problems of such conventional technologies. An object of the present invention is to provide a power transmission mechanism and a steering column device that can suppress play in the screwed portion between a male screw shaft member and a female screw member with a simpler configuration. [Means for solving the problem]

[0006] A power transmission mechanism according to an aspect of the present invention comprises a male screw shaft member rotatably provided on either a support portion or a movable portion and having a male screw formed along the axial direction, and a female screw member provided on the other of the support portion or the movable portion and into which the male screw shaft member is screwed, wherein the rotation of the male screw shaft member causes the female screw member and the male screw shaft member to move relative to each other, and the movable portion to move relative to the support portion, wherein the male screw shaft member and the female screw member each have a multi-start thread, and in the multi-start thread of either the male screw shaft member or the female screw member, the threading start position of at least one thread is displaced circumferentially by a predetermined angle from an angle obtained by dividing 360 degrees by the number of threads in the multi-start thread with respect to the threading start position of other threads adjacent in the circumferential direction.

[0007] A steering column device according to an aspect of the present invention includes a male screw shaft member rotatably mounted on either a support portion or a movable portion and having a male screw formed along the axial direction, and a female screw member mounted on the other of the support portion or the movable portion and into which the male screw shaft member is screwed, and a power transmission mechanism which causes the female screw member and the male screw shaft member to move relative to each other by the rotation of the male screw shaft member, and the movable portion to move relative to the support portion, wherein the male screw shaft member and the female screw member each have a multi-start screw, and in the multi-start screw of either the male screw shaft member or the female screw member, the threading start position of at least one screw is displaced circumferentially by a predetermined angle from an angle obtained by dividing 360 degrees by the number of threads in the multi-start screw with respect to the threading start position of other screws adjacent in the circumferential direction. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a power transmission mechanism and a steering column device that can suppress play in the threaded portion between the male screw shaft member and the female screw member with a simpler configuration. [Brief explanation of the drawing]

[0009] [Figure 1]This is a perspective view showing an example of a steering device according to this embodiment. [Figure 2] This is a perspective view showing the power transmission mechanism according to this embodiment. [Figure 3] This is a cross-sectional view showing the screw shaft screwed into the drive member. [Figure 4] This is a cross-sectional view showing an enlarged view of section A in Figure 3. [Figure 5] Figure 3 is a schematic view of the drive member unit as indicated by the line BB. [Figure 6] Figure 3 is a schematic cross-sectional view of a single screw shaft using the BB line. [Figure 7] This is a schematic view of the drive member unit in a modified example corresponding to line BB in Figure 3. [Figure 8] This is a schematic cross-sectional view of a single screw shaft corresponding to the modified example shown by line BB in Figure 3. [Modes for carrying out the invention]

[0010] The power transmission mechanism and steering column device according to this embodiment will be described in detail below with reference to the drawings. Note that the dimensional ratios in the drawings are exaggerated for illustrative purposes and may differ from the actual ratios.

[0011] Figure 1 shows the steering column device 1 according to this embodiment. When the steering column device 1 is mounted on the vehicle body, the direction indicated by the arrow FR in Figure 1 is the front of the vehicle body. Hereinafter, "front" refers to the front of the vehicle body, "rear" refers to the rear of the vehicle body, and "left / right direction" refers to the left / right direction when viewed from the rear of the vehicle body towards the front.

[0012] The steering column device 1 comprises a vehicle mounting bracket 3 attached to the vehicle body (not shown), an outer column 5 supported so as to be able to swing vertically relative to the vehicle mounting bracket 3, and an inner column 7 that is movable in the longitudinal direction relative to the outer column 5. The vehicle mounting bracket 3 has mounting parts 3a at multiple locations and is attached to the vehicle body via the mounting parts 3a.

[0013] The outer column 5 swings vertically with respect to the vehicle body mounting bracket 3 via a tilt drive motor 21, a power transmission mechanism 40 that operates by the tilt drive motor 21, a link mechanism 23, and the like. These tilt drive motor 21, power transmission mechanism 40, link mechanism 23, etc. are provided on the right side of the steering column device 1. The power transmission mechanism 40 has a screw shaft 43 as a male screw shaft member and a drive member 45 as a female screw member. When the outer column 5 swings vertically, the inner column 7 and the steering shaft 9 rotatably inserted into the inner column 7 also swing integrally. A steering wheel (not shown) is attached to the rear end of the steering shaft 9.

[0014] Therefore, the steering column device 1 includes a tilt mechanism 20 that allows the steering wheel to swing vertically. The steering column device 1 further includes a telescopic mechanism 10 that allows the steering wheel to move back and forth.

[0015] The telescopic mechanism 10 includes a telescopic drive motor 11 as an electric actuator attached to the left side of the outer column 5. The telescopic drive motor 11 is attached to the outer column 5 together with a speed reduction mechanism unit 12. A screw shaft 33 that is rotationally driven by the telescopic drive motor 11 extends along the axial direction of the cylindrical inner column 7.

[0016] Also, the telescopic mechanism 10 has a power transmission mechanism 30, also referred to as a feed screw mechanism.

[0017] Hereinafter, the power transmission mechanisms 30 and 40 according to this embodiment will be described.

[0018] Figures 2, 3, and 4 show the power transmission mechanism 30 provided in the telescopic mechanism 10. Figure 5 shows the drive member 35 alone, and Figure 6 shows the screw shaft 33 alone. Note that since the power transmission mechanism 40 provided in the tilt mechanism 20 is configured in the same manner as the power transmission mechanism 30 provided in the telescopic mechanism 10, a detailed description of the power transmission mechanism 40 on the tilt mechanism 20 side will be omitted.

[0019] The power transmission mechanism 30 has a screw shaft 33 as a male screw shaft member and a drive member 35 as a female screw member.

[0020] The screw shaft 33 as a male screw shaft member includes a screw shaft portion 33a with which the drive member 35 is screwed, and a front-side screw shaft portion (not shown) located forward with respect to the screw shaft portion 33a. Further, the screw shaft 33 includes a shaft portion (not shown) located between the screw shaft portion 33a and the front-side screw shaft portion. The screw shaft 33 is supported by the reduction mechanism portion 12 at the shaft portion.

[0021] The shaft portion of the screw shaft 33 is rotatable with respect to the reduction mechanism portion 12 while axial movement with respect to the reduction mechanism portion 12 is restricted. Depending on the mounting position or shape of the telescopic drive motor 11 or the reduction mechanism portion 12, the screw shaft 33 can also be connected to the reduction mechanism portion 12 using a flexible shaft (not shown).

[0022] The drive member 35 as a female screw member includes a nut portion 35a. The drive member 35 is attached to a bracket 13 (see Figure 1), and this bracket 13 is attached to the inner column 7 through an opening (not shown) provided in the outer column 5. Therefore, by driving the telescopic drive motor 11 and rotating the screw shaft 33, the drive member 35 moves back and forth along the screw shaft 33. Along with this, the inner column 7 as a movable part moves back and forth with respect to the outer column 5 as a support part together with the steering shaft 9.

[0023] In this embodiment, the screw shaft 33 (screw shaft portion 33a) and the drive member 35 (nut portion 35a) are each formed with multi-start threads. In the multi-start thread of either the screw shaft portion 33a or the nut portion 35a, the starting point of at least one thread (thread cutting start position) is shifted by several degrees in the circumferential direction relative to the starting point of other threads adjacent in the circumferential direction. By doing so, the phase of the multi-start thread with the shifted starting point is changed, and by shifting the phase with the other multi-start thread, play in the threaded portion between the screw shaft 33 and the drive member 35 can be suppressed.

[0024] In the embodiment shown in Figures 2 to 6, the screw shaft 33 (screw shaft portion 33a) and the drive member 35 (nut portion 35a) are each formed with a double-start thread. In this case, the screw shaft portion 33a is composed of a first-start male thread portion S1 and a second-start male thread portion S2. These first-start male thread portion S1 and second-start male thread portion S2 are arranged at the same interval (pitch) Ps (see Figure 4). Furthermore, when the screw shaft 33 is viewed from the axial direction, the first-start male thread portion S1 and second-start male thread portion S2 are arranged at an angle As (180°) obtained by dividing the circumference of 360 degrees by the number of threads in the multi-start thread (see Figure 6). On the other hand, the nut portion 35a is composed of a first-start female thread portion N1 and a second-start female thread portion N2. In this embodiment, the starting point of the thread in the second female thread portion N2 is shifted circumferentially by a few degrees (3 degrees in this embodiment) from the angle An (180°) obtained by dividing the circumference of 360 degrees by the number of threads in the multi-start thread, relative to the starting point of the thread in the first female thread portion N1 (see Figure 5). The angle α of this circumferential shift is preferably in the range of 1 to 5 degrees, considering the sliding resistance during driving. In Figure 4, for the sake of explanation, the second female thread portion N2, in which the starting point of the thread has been shifted, is shown with dot hatching in addition to the normal hatching.

[0025] As mentioned above, in a multi-start screw, the starting point of the second female thread N2 is shifted circumferentially by a few degrees (angle α) from angle An relative to the starting point of the first female thread N1. By doing this, the phase of the second female thread N2, whose starting point has been shifted, changes, and its phase shifts relative to the first female thread N1. As a result, as shown in Figure 4, the distance between the first female thread N1 and the second female thread N2 is changed from an equal distance (equal pitch) Pn to a distance β, forming two different distances: a short (narrow) distance Pns and a long (wide) distance Pnl.

[0026] Therefore, when the screw shaft 33 is screwed into the drive member 35, the threads of the two female threads N1 and N2 contact the threads of the second male thread S2 in Figure 4, sandwiching them between them. That is, the threads of the first female thread N1 contact the threads of the second male thread S2 from the left in Figure 4. Conversely, the threads of the second female thread N2 contact the threads of the second male thread S2 from the right in Figure 4. As a result, the relative axial movement between the screw shaft portion 33a of the screw shaft 33 and the nut portion 35a of the drive member 35 is restricted, and the play in the screw threaded portion between them is suppressed, thereby suppressing play in the steering shaft 9.

[0027] Furthermore, as shown in the modified examples in Figures 7 and 8, the screw shaft 33 (screw shaft portion 33a) and the drive member 35 (nut portion 35a) can each be formed with a three-start thread. In this case, the screw shaft portion 33a is composed of a first-start male thread portion S1, a second-start male thread portion S2, and a third-start male thread portion S3. Although not shown in the figures, these first-start male thread portions S1, S2, and S3 are arranged at the same interval (pitch). Also, when the screw shaft 33 is viewed from the axial direction, the first-start male thread portion S1, S2, and S3 are arranged at an angle As (120°) obtained by dividing the circumference of 360 degrees by the number of starts in the multi-start thread (see Figure 8). On the other hand, the nut portion 35a is composed of a first female thread portion N1, a second female thread portion N2, and a third female thread portion N3. In Figure 7, the starting point of the thread in the third female thread portion N3 is shifted circumferentially by a few degrees (angle α) from the angle An (120°) obtained by dividing the circumference of 360 degrees by the number of threads in the multi-start screw, relative to the starting point of the thread in the second female thread portion N2. By doing this, in a multi-start screw, by shifting the starting point of at least one thread by a few degrees (angle α) in the circumferential direction, the phase of the thread is changed, and the phase with respect to the other component can be shifted. As a result, the relative axial movement between the screw shaft portion 33a of the screw shaft 33 and the nut portion 35a of the drive member 35 is restricted, and the play in the screw threaded portion between them is suppressed, thereby suppressing play in the steering shaft 9.

[0028] The effects and advantages of this embodiment will be explained below.

[0029] (1) The power transmission mechanism 30 comprises a male screw shaft member (screw shaft 33) rotatably mounted on either the support part or the movable part, with male screws (male screw parts S1, S2) formed along the axial direction, and a female screw member (drive member 35) mounted on either the support part or the movable part, with the male screw shaft member (screw shaft 33) screwed into it. The rotation of the male screw shaft member (screw shaft 33) causes the female screw member (drive member 35) and the male screw shaft member (screw shaft 33) to move relative to each other, causing the movable part to move relative to the support part. The male screw shaft member (screw shaft 33) and the female screw member (drive member 35) each have multi-start threads. In a multi-start screw of either the male screw shaft member (screw shaft 33) or the female screw member (drive member 35), the threading start position of at least one screw (the second female thread portion N2) is displaced circumferentially by a predetermined angle α from an angle An obtained by dividing 360 degrees by the number of threads in the multi-start screw, relative to the threading start position of another screw (the first female thread portion N1) adjacent in the circumferential direction.

[0030] In a multi-start screw, by shifting the starting point of at least one screw by a few degrees (angle α) in the circumferential direction, the phase of the screw can be changed, thereby shifting its phase relative to the other component. This suppresses play between the screw shaft portion 33a of the screw shaft 33 and the nut portion 35a of the drive member 35, and since there is no need to provide a separate part to suppress play, the number of parts can be reduced.

[0031] As described above, according to this embodiment, a power transmission mechanism 30 can be provided that can suppress play in the threaded portion between the male screw shaft member (screw shaft 33) and the female screw member (drive member 35) with a simpler configuration.

[0032] (2) The predetermined angle α mentioned above is within the range of 1 to 5 degrees.

[0033] A suitable angle for shifting the starting point of at least one screw thread by several degrees in the circumferential direction is within the range of 1 to 5 degrees. If this range is exceeded, sliding resistance will occur during operation, and there is a risk that the male screw shaft member (screw shaft 33) and the female screw member (drive member 35) will not be able to slide against each other. On the other hand, within this range, it is possible to suppress play in the threaded portion between the male screw shaft member (screw shaft 33) and the female screw member (drive member 35) without affecting sliding resistance.

[0034] (3) The steering column device 1 includes a male screw shaft member (screw shaft 33) which is rotatably mounted on either the support part or the movable part and has male screws (male screw parts S1, S2) formed along the axial direction, and a female screw member (drive member 35) which is mounted on either the support part or the movable part and into which the male screw shaft member (screw shaft 33) is screwed, and a power transmission mechanism 30 which causes the female screw member (drive member 35) and the male screw shaft member (screw shaft 33) to move relative to each other as the male screw shaft member (screw shaft 33) rotates, and the movable part to move relative to the support part. The male screw shaft member (screw shaft 33) and the female screw member (drive member 35) each have multi-start threads. In a multi-start screw of either the male screw shaft member (screw shaft 33) or the female screw member (drive member 35), the threading start position of at least one screw (the second female thread portion N2) is displaced circumferentially by a predetermined angle α from an angle An obtained by dividing 360 degrees by the number of threads in the multi-start screw, relative to the threading start position of another screw (the first female thread portion N1) adjacent in the circumferential direction.

[0035] In a multi-start screw, by shifting the starting point of at least one screw by several degrees in the circumferential direction, the phase of the screw is changed, and the phase difference with respect to other parts can be shifted. As a result, play between the screw shaft portion 33a of the screw shaft 33 and the nut portion 35a of the drive member 35 can be suppressed, and since there is no need to provide a separate part to suppress the play, the number of parts can be reduced.

[0036] As described above, according to this embodiment, a steering column device 1 can be provided that can suppress play in the threaded portion between the male screw shaft member (screw shaft 33) and the female screw member (drive member 35) with a simpler configuration.

[0037] (4) The predetermined angle α is within the range of 1 to 5 degrees.

[0038] A suitable angle for shifting the starting point of at least one screw thread by several degrees in the circumferential direction is within the range of 1 to 5 degrees. If this range is exceeded, sliding resistance will occur during operation, and there is a risk that the male screw shaft member (screw shaft 33) and the female screw member (drive member 35) will not be able to slide against each other. On the other hand, within this range, it is possible to suppress play in the threaded portion between the male screw shaft member (screw shaft 33) and the female screw member (drive member 35) without affecting sliding resistance.

[0039] (5) The steering column device 1 is equipped with a tilt mechanism 20 that swings the steering wheel up and down, and this tilt mechanism 20 has a power transmission mechanism 40.

[0040] In a power transmission mechanism 40 using a female threaded member (drive member 45) and a male threaded shaft member (screw shaft 43), the male threaded shaft member (screw shaft 43) and the female threaded member (drive member 45) are each formed with multi-start threads. By shifting the starting point of at least one thread in the multi-start thread of either the male threaded shaft member (screw shaft 43) or the female threaded member (drive member 45) by several degrees in the circumferential direction, the phase of the thread is changed, and the phase with respect to the other component can be shifted. As a result, play in the threaded portion between the screw shaft 43 and the drive member 45 can be suppressed, and since there is no need to provide a separate part to suppress play, the number of parts can be reduced.

[0041] (6) The steering column device 1 is equipped with a telescopic mechanism 10 that moves the steering wheel in the forward and backward directions, and this telescopic mechanism 10 has a power transmission mechanism 30.

[0042] In a power transmission mechanism 30 using a female threaded member (drive member 35) and a male threaded shaft member (screw shaft 33), both the male threaded shaft member (screw shaft 33) and the female threaded member (drive member 35) are formed with multi-start threads. By shifting the starting point of at least one thread in the multi-start thread of either the male threaded shaft member (screw shaft 33) or the female threaded member (drive member 35) by several degrees in the circumferential direction, the phase of the thread is changed, and the phase with respect to the other component can be shifted. As a result, play in the threaded portion between the screw shaft 33 and the drive member 35 can be suppressed, and since there is no need to provide a separate part to suppress play, the number of parts can be reduced.

[0043] Although this embodiment has been described above, this embodiment is not limited to these, and various modifications are possible within the scope of the gist of this embodiment. [Explanation of symbols]

[0044] 1. Steering column device 5. Outer column (support part) 7. Inner column (movable part) 10 Telescopic mechanism 20 Tilt mechanism 30 Power transmission mechanism 33. Screw shaft (male screw shaft component) 33a Screw shaft 35 Drive member (female thread member) 35a Nut section 40 Power transmission mechanism 43 Screw shaft (male screw shaft component) 45 Drive member (female thread member) N1 Female thread section N2 Female thread section N3 Female thread section S1 Male thread section S2 Male thread section S3 Male thread section

Claims

1. A male screw shaft member is rotatably mounted on either the support part or the movable part, and has a male thread formed along the axial direction. The system comprises a female threaded member provided on either the support portion or the movable portion, into which the male threaded shaft member is screwed, A power transmission mechanism in which the rotation of the male screw shaft member causes the female screw member and the male screw shaft member to move relative to each other, and the movable part moves relative to the support part, The male threaded shaft member and the female threaded member each have multiple threads, In the multi-start thread of either the male threaded shaft member or the female threaded member, the threading start position of at least one thread is displaced circumferentially by a predetermined angle from an angle obtained by dividing 360 degrees by the number of threads in the multi-start thread, relative to the threading start position of other threads adjacent in the circumferential direction. Power transmission mechanism.

2. The power transmission mechanism according to claim 1, wherein the predetermined angle is within the range of 1 to 5 degrees.

3. The power transmission mechanism comprises a male screw shaft member rotatably mounted on either the support portion or the movable portion and having a male screw formed along the axial direction, and a female screw member mounted on the other of the support portion or the movable portion and into which the male screw shaft member is screwed, wherein the rotation of the male screw shaft member causes the female screw member and the male screw shaft member to move relative to each other, and the movable portion to move relative to the support portion, The male threaded shaft member and the female threaded member each have multiple threads, In the multi-start thread of either the male threaded shaft member or the female threaded member, the threading start position of at least one thread is displaced circumferentially by a predetermined angle from an angle obtained by dividing 360 degrees by the number of threads in the multi-start thread, relative to the threading start position of other threads adjacent in the circumferential direction. Steering column device.

4. The steering column device according to claim 3, wherein the predetermined angle is within the range of 1 to 5 degrees.

5. It features a tilt mechanism that allows the steering wheel to swing up and down. The tilt mechanism has the power transmission mechanism. The steering column device according to claim 3 or 4.

6. It features a telescopic mechanism that allows the steering wheel to move forward and backward. The telescopic mechanism has the power transmission mechanism. The steering column device according to claim 3 or 4.

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