JP2018030385A - Vehicle steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vehicle steering device which enables weight reduction of a screw shaft while maintaining performance needed for the screw shaft forming at least one of an electric telescopic mechanism and an electric tilt mechanism.SOLUTION: A vehicle steering device includes: a screw shaft 70 coupled to an electric motor 60 through a wheel gear 61; and a nut member 50 which is threadedly engaged with the screw shaft and axially moves in response to rotation of the screw shaft. The screw shaft has: a male screw part 71 which is threadedly engaged with the nut member; and a connection part 72 located adjacent to the male screw part and coupled to the wheel gear. The screw shaft includes the connection part and the male screw part and has an integral structure of aluminium alloy.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a steering apparatus for a vehicle, and in particular, at least one of an electric telescopic mechanism that drives a steering wheel disposed in a steering column in a longitudinal direction with respect to a vehicle body and an electric tilt mechanism that drives the steering wheel in a vertical direction. The present invention relates to a steering apparatus including

  An electric motor that supports the steering column, a screw shaft that is connected to the electric motor via a wheel gear, and a nut member that is screwed into the screw shaft and moves in the axial direction according to the rotation of the screw shaft. For example, the following Patent Document 1 relates to an embodiment of a steering device including: “a movable nut member is attached to a tilt screw configured in this manner, and a screw is screwed in a state in which the tilt screw is screwed into the movable nut member. The lower part of the swing arm is connected to the movable nut member via a link. ”(Described in paragraph [0029] of Patent Document 1; Drawing reference signs are omitted).

  Patent Document 1 further states that “a female thread portion is formed at the center position of the bearing presser constituting the reciprocating drive mechanism of the tilt mechanism, and the fixed nut member fixed to the lower jacket is also used. One end of a telescopic screw is screwed into the fixing nut member, and the telescopic screw is disposed substantially parallel to the axis of the upper jacket ”and“ the other end of the telescopic screw ” Is supported rotatably on the lower surface of the upper jacket via a bracket described later, and a motor is connected to the other end of the telescopic screw via a worm and a worm wheel (not shown). A motor case as a support part is attached to the upper jacket via a bracket, and the motor is accommodated in the motor case. The motor case is provided with a telescopic screw rotatably through a bush, and a pair of thrust bearings are disposed on both sides of the worm wheel integrated with the telescopic screw, and the bearing retainer is screwed into the motor case. The worm wheel is held inside the motor case ”(described in the paragraphs [0031] and [0032], however, the figure numbers and reference numerals are omitted).

JP 2009-96409 A

  In the apparatus described in Patent Document 1, “tilt screw” and “telescopic screw” correspond to the screw shaft. However, because of the structure, an iron material is generally formed by plastic working (rolling). It is recognized that a typical screw shaft is used. Conventionally, it is not necessary to consider the weight reduction of the screw shaft, but it is difficult to meet the recent demand for strict weight reduction with the conventional screw shaft.

  Accordingly, the present invention provides a steering apparatus for a vehicle including at least one of an electric telescopic mechanism and an electric tilt mechanism, which can reduce the weight of the screw shaft while maintaining the performance required for the screw shaft constituting the mechanism. It is an object to provide an apparatus.

  In order to achieve the above object, the present invention provides at least one of an electric telescopic mechanism for driving a steering wheel disposed in a steering column in the front-rear direction with respect to the vehicle body and an electric tilt mechanism for driving the steering wheel in the vertical direction. The at least one mechanism includes an electric motor supported by the steering column, a screw shaft connected to the electric motor via a wheel gear, and a screw shaft that is screwed to the screw shaft to rotate the screw shaft. In a vehicle steering apparatus comprising a nut member that moves in an axial direction in response to the male screw portion, the screw shaft is coupled to the wheel gear adjacent to the male screw portion and the male screw portion. The screw shaft including the connecting portion and the male screw portion, and the screw shaft is formed of an integral structure of an aluminum alloy. It is intended.

  In the screw shaft provided for the steering device, the male screw portion is a cold-rolled trapezoidal screw portion, the connecting portion is a cold forging serration portion, and the cold forging serration portion is It may be configured to be serrated to the wheel gear. In particular, the screw shaft is between the cold-rolled trapezoidal screw portion and the cold-forged serration portion, and has an outer diameter smaller than the outer diameter of the cold-rolled trapezoidal screw portion. It is preferable to have an intermediate portion having a larger diameter.

  Since this invention is comprised as mentioned above, there exist the following effects. That is, the screw shaft provided for the steering device of the present invention has a male screw portion screwed into the nut member and a connecting portion connected to the wheel gear adjacent to the male screw portion. Since the screw shaft including the screw portion is an integral structure of an aluminum alloy, it is possible to significantly reduce the weight while maintaining the performance required for the screw shaft.

  In the above screw shaft, if the male screw portion is a cold-rolled trapezoidal screw portion, the connecting portion is a cold forging serration portion, and the cold forging serration portion is serrated to the wheel gear, the screw A lightweight aluminum alloy monolithic product can be constructed at low cost while maintaining the performance required for the shaft. In particular, a screw having an intermediate portion between the cold-rolled trapezoidal screw portion and the cold-forged serration portion that is smaller in diameter than the cold-rolled trapezoidal screw portion and larger in diameter than the cold-forged serration portion. If the shaft is used, the performance required for the screw shaft can be reliably maintained.

It is sectional drawing which shows one Embodiment of the linear motion mechanism with which the steering apparatus of this invention is provided. It is sectional drawing which shows the cross section of the connection part in one Embodiment of this invention. In one Embodiment of this invention, it is a side view which shows the one aspect | mode of the shape between a screw part and a serration part. In one Embodiment of this invention, it is a side view which shows the other aspect of the shape between a screw part and a serration part. 1 is a side view showing an overall configuration of a steering device according to the present invention.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. First, the overall configuration of the steering apparatus according to the present invention will be described with reference to FIG. The steering shaft 1 includes a cylindrical upper shaft 1a to which a steering wheel W is connected at a rear end portion, and a lower shaft 1b that is spline-coupled to the front end portion of the upper shaft 1a. That is, the upper shaft 1a and the lower shaft 1b are coupled so as to be relatively movable in the axial direction, and the front end portion of the lower shaft 1b is connected to a turning mechanism (not shown). The steering mechanism is driven in accordance with the operation of the steering wheel W and is configured to steer a steered wheel (not shown) via a wheel steering mechanism (not shown).

  A main housing 10 is disposed coaxially with the steering shaft 1, is supported so as to be swingable about a swing center C with respect to the vehicle body B, and is held by a fixed bracket 30. The fixed bracket 30 has a pair of holding portions (represented by 31 as a representative) that extend downward from the vehicle and face each other. The main housing 10 is held between these holding portions. Fixed. Further, a pressing mechanism (not shown) is interposed between the pair of holding portions 31 of the fixing bracket 30 and the main housing 10, whereby the main housing 10 is slidably pressed and supported.

  A movable column member 20 is supported in the main housing 10 so as to be movable in the axial direction, that is, movable in the longitudinal direction of the vehicle body. As the movable column member 20, a metal inner tube 21 that houses the steering shaft 1 and supports it rotatably around an axis, and a metal that houses the inner tube 21 and holds the inner tube 21 at a predetermined position at all times. The outer tube 22 is provided. The upper shaft 1a is rotatably supported by a rear end portion of the inner tube 21 via a bearing (not shown), but the axial relative movement between the upper shaft 1a and the inner tube 21 is restricted, and the upper shaft 1a The shaft 1a and the inner tube 21 are configured so as to be able to move in the axial direction together.

  Thus, the outer tube 22, the inner tube 21, the steering shaft 1 and the steering wheel W are integrally movable with respect to the main housing 10, so that an electric telescopic mechanism (the drive mechanism is not shown) is provided. Thus, the steering wheel W can be adjusted to a desired position in the longitudinal direction of the vehicle body. Further, when a load equal to or greater than a predetermined value is applied to the steering shaft 1, the inner tube 21 is allowed to move in the axial direction relative to the outer tube 22 (and thus the upper shaft 1a moves in the axial direction). The inner tube 21 and the outer tube 22 of the present embodiment function as energy absorbing means together with an annular friction material (for example, a metal elastic bush) interposed between them.

  On the other hand, one end of the link mechanism 4 is supported on the fixed bracket 30, and the other end is connected to the drive mechanism 5, and the drive mechanism 5 is swingably supported by the main housing 10. The drive mechanism 5 allows the movable column member 20 to swing with respect to the vehicle body via the link mechanism 4 to constitute the electric tilt mechanism 3, thereby adjusting the steering wheel W to a desired vehicle body vertical position. can do. As shown in FIG. 5, the link mechanism 4 of the present embodiment is supported below the fixed bracket 30 such that the upper ends of the pair of link members 41 are rotatable about the pivot axis P1, and the lower ends thereof are linked. The member 42 is supported at the rear upper end of the member 42 so as to be rotatable about the pivot axis P2.

  The link member 42 is formed in a bell crank shape, and the main housing 10 is sandwiched between a pair of arms, and is supported below the main housing 10 so as to be rotatable about the pivot shaft P3. The link member 42 is supported rotatably about the pivot axis P4 in such a manner that the nut member 50 is sandwiched between the pair of leg portions 42. The nut member 50 constitutes the drive mechanism 5 together with the screw shaft 70 and the like, and is used as a drive source of the electric tilt mechanism 3, and is also called a tilt nut or a tilt slider.

  Thus, when the nut member 50 moves in the axial direction of the screw shaft 70 in accordance with the rotational drive of the screw shaft 70 by the electric motor 60, the link member 42 swings about the pivot shaft P3 and the link member 41. Swings about the pivot axis P1, and the main housing 10 (and the outer tube 22, the inner tube 21, the upper shaft 1a, and the steering wheel W) are configured to move in the vertical direction of the vehicle body. In the present embodiment, a speed reduction mechanism (not shown) including a wheel gear (61 in FIG. 1 described later) is interposed between the output shaft of the electric motor 60 and the screw shaft 70. Is appropriately decelerated and transmitted to the screw shaft 70.

  1 and 2 show an embodiment of a linear motion mechanism used in the above steering device. A screw shaft 70 includes a male screw portion 71 screwed into a nut member 50, and a male screw portion 71. A connecting portion 72 connected to the wheel gear 61 is provided adjacent thereto, and the connecting portion 72 and the male screw portion 71 are included to form an integral structure of an aluminum alloy. In particular, the male screw portion 71 has a trapezoidal screw formed by cold rolling of a high-strength and high-strength aluminum alloy, and the connecting portion 72 has a serration portion formed by cold forging the aluminum alloy. That is, the male screw portion 71 is constituted by a cold-rolled trapezoidal screw portion, and the connecting portion 72 is constituted by a cold forging serration portion, and this cold forging serration portion (72) is serrated and coupled to the wheel gear 61. The

  As shown in FIGS. 2 and 3, the screw shaft 70 of the present embodiment includes a cold-rolled trapezoidal screw portion between the cold-rolled trapezoidal screw portion (71) and the cold-forged serration portion (72). It has an intermediate portion 74 that is smaller than the outer diameter of (71) and larger than the outer diameter of the cold forging serration portion (72) and is formed by cold forging. Thus, it is possible to reduce the weight of the screw shaft 70 while maintaining the performance required for the screw shaft 70. For example, the weight can be reduced by 65% with respect to the conventional iron screw shaft. In particular, since the burr removal process or the like is unnecessary, the yield of the material can be improved. Further, the screw shaft 70 is formed with a male screw portion 73 and a flange portion 75 smaller in diameter than the male screw portion 71 by cold forging (simultaneously with the connecting portion 72 and the intermediate portion 74). Thus, as shown in FIGS. 1 and 2, the thrust bearings 81 and 82 are mounted, the thrust force adjusting nut 83 is screwed into the male screw portion 73, and the nut 84 for fixing the wheel gear 61 is screwed. Worn.

  FIG. 4 shows another embodiment of the shape between the male screw portion 71 and the serration portion 72. Similar to the cold-rolled trapezoidal screw portion (71) of the male screw portion 71, FIG. 72x) is also a cold-rolled serration portion, but according to this, it becomes inevitable to form a constricted portion 76 having a diameter smaller than the outer diameter of the serration portion 72x. Therefore, as in the above-described embodiment, it is desirable that the connection portion 72 of the cold forging serration portion is continuous with the intermediate portion 74 as shown in FIG.

DESCRIPTION OF SYMBOLS 1 Steering shaft 3 Tilt mechanism 4 Link mechanism 5 Drive mechanism 10 Main housing 20 Movable column member 30 Fixed bracket 50 Nut member 51 Female screw part 52 Pivot shaft part 60 Electric motor
70 screw shaft 71 male screw part 72 serration part 73 male screw part 74 intermediate part 75 collar part

Claims (3)

  At least one of an electric telescopic mechanism that drives a steering wheel disposed in a steering column in a longitudinal direction with respect to a vehicle body and an electric tilt mechanism that drives the steering wheel in a vertical direction; An electric motor supported by the column; a screw shaft connected to the electric motor via a wheel gear; and a nut member that is screwed to the screw shaft and moves in the axial direction in accordance with the rotation of the screw shaft. In the vehicle steering apparatus, the screw shaft has a male screw portion screwed into the nut member, and a connecting portion connected to the wheel gear adjacent to the male screw portion, and the connecting portion and A vehicle steering apparatus comprising the male screw portion and the screw shaft having an integral structure of an aluminum alloy.   In the screw shaft, the male screw portion is a cold-rolled trapezoidal screw portion, the connecting portion is a cold forging serration portion, and the cold forging serration portion is serrated to the wheel gear. The vehicle steering device according to claim 1.   The screw shaft is between the cold-rolled trapezoidal screw portion and the cold-forged serration portion, smaller in diameter than the outer diameter of the cold-rolled trapezoidal screw portion and larger than the outer diameter of the cold-forged serrated portion. The vehicle steering apparatus according to claim 2, further comprising an intermediate portion of the diameter.

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