JP2009046004A - Coupling device for steering shaft - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coupling device for a steering shaft that facilitates coupling between the end part of a first shaft and the end part of a second shaft. <P>SOLUTION: A female member 121 is inserted from the side of a lower shaft 105 so as to cover a male member 120. The internal-thread part 121a of the female member is screwed to the male screw part 120b of the male member. By this, the tapered inner face 121b is brought close to the tapered outer face 120c so as to finally press the tapered outer face 120c by the tapered inner face 121b. Accordingly, the diameter of the tapered outer face 120c is reduced. On that occasion, a slit 120e acts so as to facilitate the diameter reduction of the male member 120. By this, the female serration part 120a of the male member 120, a second male serration part 105b of the lower shaft 105, and a male serration part 112a of an input shaft 112 are brought into close contact with each other. Therefore, backlash among them is eliminated. Consequently, the lower shaft 105 and the input shaft 112 are coupled with each other so as to be integrally rotated via the male member 120. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a steering shaft coupling device used in a steering system constituting a steering device for an automobile or the like.

  In recent years, from the viewpoint of energy saving and the like, an increasing number of vehicles adopt an electric power steering device from a hydraulic power steering device. For example, in a column type electric power steering apparatus, a power unit including a motor and a speed reducer is arranged in the steering column. However, since the steering shaft is usually separate from the power unit, the steering shaft is attached to the power unit. It is necessary to connect the power transmission.

  Here, serration connection is known as a method of connecting shafts. More specifically, a female serration is formed on one shaft, a male serration is formed on the other shaft, and the serrations can be engaged with each other so that the shafts can be integrally rotated. However, in the case of a general serration connection, there is a backlash between the female serration and the male serration, so simply engaging the serrations causes a power transmission delay due to the backlash, and the driver feels uncomfortable. There is a risk of giving.

On the other hand, in the steering system shown in Patent Document 1, rubber or the like is provided between the buffering convex portion formed on the outer periphery of the end portion of the steering shaft and the buffering concave portion formed on the inner periphery of the end portion of the input shaft. The buffer member which consists of this is inserted, and, thereby, the rattling between a steering shaft and an input shaft is suppressed.
JP 2007-155117 A

  However, it is troublesome to dispose the buffer member as shown in Patent Document 1 between the steering shaft and the input shaft. In addition, when used in a relatively heavy vehicle or when frequent stationary, etc., there is a risk that the buffer member will become loose early. On the other hand, if the interference member is periodically replaced, the problem of settling can be avoided, but there is a problem that the burden of maintenance increases.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a steering shaft coupling device that can easily connect an end portion of a first shaft and an end portion of a second shaft. And

A steering shaft coupling device according to the present invention includes a steering shaft that coaxially connects an end portion of a first shaft and an end portion of a second shaft, each of which has an outer circumferential shape formed with a periodic uneven outer shape. In the coupling device of
A hollow male member provided with an inner peripheral surface corresponding to the outer shape of the concave / convex shape on the inner peripheral surface, a male screw portion, and a tapered outer surface having a diameter reduced toward the end portion on the outer peripheral surface;
A hollow female member having a female screw portion corresponding to the male screw portion and a tapered inner surface corresponding to the tapered outer surface;
The male member is attached so as to enclose the end portion of the first shaft and the end portion of the second shaft while engaging the inner shape of the unevenness with the outer shape of the unevenness. The taper outer surface is pressed against the taper inner surface in the direction orthogonal to the axis by attaching the female member to the male member so that the female screw portion is screwed.

  According to the present invention, the male member is attached so as to enclose the end portion of the first shaft and the end portion of the second shaft while engaging the inner shape of the unevenness with the outer shape of the unevenness. Thereafter, the female screw portion is screwed into the male screw portion, and the female member is attached to the male member, whereby the tapered inner surface is pressed inward in the direction perpendicular to the axis. Therefore, the backlash between the first shaft and the second shaft can be effectively eliminated despite the ease of assembly. The irregular outer shape may be male serration and the irregular inner shape may be female serration, but may be simple irregularities.

  It is preferable that the male member is formed with a notch or a slit in the axial direction because the male member can easily come into close contact with the first shaft and the second shaft.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view of a column type electric power steering apparatus 100 according to the present embodiment. In FIG. 1, a housing 101 fixed to a vehicle body (not shown) includes a hollow housing main body 101A formed of aluminum or an aluminum alloy, magnesium or a magnesium alloy, a lid member 101B attached to the housing main body 101A, and a tubular shape. Outer column 101C. A motor 102 is attached to the housing main body 101A. An inner column 103 is slidably inserted into the outer column 101C in a nested manner.

  A hollow upper shaft 104 to which a steering wheel (not shown) is attached at the right end in FIG. 1 is inserted into the inner column 103 and is rotatably supported by the bearing 103 with respect to the inner column 103.

  A female serration 104a is formed on the inner periphery of the upper end of the upper shaft 104 in FIG. On the other hand, a first male serration portion 105a is formed on the outer periphery of the right end of the lower shaft 105 in FIG. The lower shaft 105 is coaxially connected to the upper shaft 104 by engaging the first male serration portion 105a with the female serration portion 104a.

  A second male serration portion 105b is formed on the outer periphery of the left end of the lower shaft 105 in FIG. The input shaft 112 is disposed so that the right end of the lower shaft 105 in FIG. A male serration portion 112a is formed on the outer periphery of the right end of the input shaft 112 in FIG.

  In FIG. 1, an input shaft 112 and an output shaft 113 are coaxially arranged in the housing main body 101A. In the present embodiment, the input shaft 112 is not directly supported by the bearing, but may be supported by the bearing with respect to the housing main body 101A. One end of a core metal 118a of an annular worm wheel 118 is fitted around the hollow output shaft 113, and further, the output shaft 113 and the deep groove ball bearing 114 fitted and arranged around the core metal 118a. One end of the worm wheel 118 is rotatably supported with respect to the housing main body 101A. The other end of the cored bar 118a is rotatably supported by the deep groove ball bearing 115 with respect to the housing main body 101A extending to the inside thereof.

  In FIG. 1, a torsion bar 116 having a right end pin-coupled to the input shaft 112 and connected by press-fitting the left end to the output shaft 113 extends in the input shaft 112. A detection device, that is, a torque sensor 117 for detecting steering torque based on the torsion bar 116 being twisted in proportion to the received torque is provided at a position facing the outer periphery of the input shaft 112. The torque sensor 117 is a rotary non-contact torque sensor, and detects relative angular displacement between the input shaft 112 and the output shaft 113 based on torsion of the torsion bar 116 as a change in impedance in a predetermined magnetic circuit by a coil. As an electric signal, it is output to an ECU (not shown) assembled in the housing 101.

  The worm wheel 118 disposed in the housing main body 101A includes a core metal 118a attached to the output shaft 113 so as to rotate integrally, and a resin tooth portion 118b formed by insert molding on the outer periphery thereof. The tooth portion 118 b of the worm wheel 118 meshes with a worm (not shown) formed integrally with the rotating shaft of the motor 102 attached to the housing 101. The worm wheel 118 and the worm constitute a reduction gear mechanism.

  FIG. 2 is an enlarged view of a portion indicated by an arrow II in the configuration of FIG. FIG. 3A is a side view of the male member 120, and FIG. 3B is a front view of the male member 120. FIG. 4A is a sectional view in the axial direction of the female member 121, and FIG. 4B is a front view of the female member 121. The male member 120 and the female member 121 constitute a coupling device.

  As shown in FIG. 3, the hollow male member 120 has a female serration corresponding to the second male serration portion 105 b of the lower shaft (first axis) 105 and the male serration portion 112 a of the input shaft (second axis) 112. The portion 120a is formed on the inner periphery. Further, the male member 120 has a male screw portion 120b on the left outer peripheral surface in FIG. 3A, and a tapered outer surface 120c having a diameter decreasing toward the end portion on the right outer peripheral surface. . The male screw portion 120b and the tapered outer surface 120c are partitioned by a circumferential groove 120d. Furthermore, the male member 120 forms a slit 120e over the entire axial length.

  As shown in FIG. 4, the hollow female member 121 has a female screw portion 121a on the left inner peripheral surface in FIG. 4 (a), and the right inner peripheral surface has a reduced diameter toward the end portion. A tapered inner surface 121b is formed. The internal thread 121a and the tapered inner surface 121b are partitioned by a circumferential groove 121c. In addition, the outer periphery of the female member 121 is generally cylindrical, but four planes 121d in which the surfaces adjacent in the circumferential direction are orthogonal to each other are formed. The flat surface 121d is a portion to which a tool (not shown) is engaged when the female member 121 is screwed to the male member 120. The female member 121 may have a hexagonal column shape, that is, it is sufficient if the outer peripheral surface has an asymmetrical shape.

  At the time of assembly, in FIG. 1, in a state before the outer column 101C is attached to the housing main body 101A, the end of the lower shaft 105 is opposed to the end of the input shaft 112 exposed from the housing main body 101A. The female serration portion 120 a of the inserted male member 120 is engaged with the second male serration portion 105 b of the lower shaft 105 and the male serration portion 112 a of the input shaft 112.

  Next, the female member 121 inserted from the lower shaft 105 side is put on the male member 120, and the female screw portion 121a is screwed into the male screw portion 120b using a tool (not shown). As a result, the taper inner surface 121b approaches the taper outer surface 120c, and finally the taper inner surface 121b presses the taper outer surface 120c radially inward, so that the taper outer surface 120c is reduced in diameter. At this time, the slit 120e acts to facilitate the diameter reduction of the male member 120. Accordingly, the female serration portion 120a of the male member 120, the second male serration portion 105b of the lower shaft 105, and the male serration portion 112a of the input shaft 112 are close to each other, thereby eliminating backlash between the two and the lower shaft. 105 and the input shaft 112 are connected so as to rotate integrally through the male member 120. Thereafter, the outer column 101C is put on the lower shaft 105 and attached to the housing main body 101A. In addition, you may apply | fill the filler etc. for locking | loosening to at least one of the internal thread part 121a and the external thread part 120b.

  Next, the operation of the present embodiment will be described. If the vehicle is in a straight traveling state and no steering force is input from the steering wheel (not shown) to the input shaft 112, the torque sensor 117 does not generate an output signal, and therefore the motor 102 does not generate an auxiliary steering force.

  On the other hand, when the driver operates a steering wheel (not shown) when the vehicle is going to turn a curve, the rotational force is transmitted to the input shaft 112 via the upper shaft 104, and accordingly, according to the rotational force. Thus, the torsion bar 116 is twisted and relative rotation occurs between the input shaft 112 and the output shaft 113. The torque sensor 117 outputs a torque signal according to the direction and amount of this relative rotation. The ECU supplies a predetermined three-phase motor current to the motor 102 based on a control map or the like set in advance from the torque signal and a vehicle speed signal from a sensor (not shown). Generate power. The torque generated by the motor 102 is decelerated by the reduction gear mechanism (118) and transmitted to the output shaft 113 to assist the movement of the rack shaft meshing with a pinion shaft (not shown). As a result, the steering mechanism is operated via the tie rod, and a wheel (not shown) can be steered.

  FIG. 5 is a side view showing a male member 120 ′ according to a modification of the present embodiment. In this modification, the two male members 120 of FIG. 3 are arranged so as to face each other and are integrally connected via an intermediate cylinder 120f. Therefore, it is necessary to engage two female members 121 shown in FIG. 4 from both sides with respect to the male member 120 ′ shown in FIG. 5. Since other configurations are the same as those in the above-described embodiment, the same reference numerals are given and description thereof is omitted.

  The present invention has been described above with reference to the embodiments. However, the present invention should not be construed as being limited to the above-described embodiments, and can be modified or improved as appropriate. For example, instead of providing a slit in the male member, a thin notch may be provided on the tapered outer surface side from the end. In such a case, a plurality of notches can be formed instead of one. Further, rattling can be more effectively eliminated by changing the height of the serrations of the male member and the female member.

1 is a cross-sectional view of a column type electric power steering apparatus 100 according to the present embodiment. It is a figure which expands and shows the site | part shown by the arrow II in the structure of FIG. FIG. 3A is a side view of the male member 120, and FIG. 3B is a front view of the male member 120. FIG. 4A is a sectional view in the axial direction of the female member 121, and FIG. 4B is a front view of the female member 121. It is a side view showing male member 120 'concerning a modification of this embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Electric power steering apparatus 101 Housing 101A Housing main body 101B Cover member 101C Outer column 102 Motor 103 Inner column 103 Bearing 104 Upper shaft 104a Female serration part 105 Lower shaft 105a First male serration part 105b Second male serration part 112 Input shaft 112a Male serration part 113 Output shaft 114 Deep groove ball bearing 115 Deep groove ball bearing 116 Torsion bar 117 Torque sensor 118 Worm wheel 118a Core metal 118b Tooth part 120, 120 'Male member 120a Female serration part 120b Male thread part 120c Tapered outer surface 120d Circumferential groove 120e Slit 120f Intermediate cylinder 121 Female member 121a Female thread portion 121b Tapered inner surface 121c Circumferential groove 121d Plane

Claims (2)

In the steering shaft coupling device that coaxially connects the end portion of the first shaft and the end portion of the second shaft, which are formed on the outer peripheral surface with a periodic uneven outer shape in the circumferential direction,
A hollow male member provided with an inner peripheral surface corresponding to the outer shape of the concave / convex shape on the inner peripheral surface, a male screw portion, and a tapered outer surface having a diameter reduced toward the end portion on the outer peripheral surface;
A hollow female member having a female screw portion corresponding to the male screw portion and a tapered inner surface corresponding to the tapered outer surface;
The male member is attached so as to enclose the end portion of the first shaft and the end portion of the second shaft while engaging the inner shape of the unevenness with the outer shape of the unevenness. The steering is characterized in that the taper outer surface is pressed inward in the direction perpendicular to the axis by attaching the female member to the male member so that the female screw portion is screwed together. Shaft coupling device.   2. The steering shaft coupling device according to claim 1, wherein the male member has a notch or a slit formed in an axial direction.

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