JP2009079677A - Yoke in steering device and coupling structure for rotary shaft - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a yoke in a steering deice and a coupling structure for rotary shafts improving fatigue strength of a universal coupling transmitting high torque rotation. <P>SOLUTION: In the yoke in a steering device and a coupling structure for rotary shafts, the yoke 3 provided with a hub 3 of a notched tube shape, a pair of flanges 35, 36 extending in parallel with each other from positions on both sides of a slit of the hub, and a pair of forks 33, 34 integrally formed on axial one end side of the hub is subjected to serration fitting on an end outer circumference of a rotary shaft 14, and it is fastened by a fastening bolt 3 connected to the pair of flanges. By this, the yoke is coupled to the rotary shaft by reducing an inner diameter of the hub such that the pair of flanges come closer and a serration fitting part is adhered closely. A load sharing member 43 sharing a part of a bending load acting on the fastening bolt is provided between the pair of flanges. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to a joint structure of a universal joint yoke and a rotary shaft incorporated in a steering device, and is particularly suitable for transmission of high torque rotation.

2. Description of the Related Art Conventionally, a cross joint universal joint called a cardan joint has been widely known as a universal joint that is incorporated in an automobile steering device and transmits the rotation of a steering shaft to a steering gear.
As shown in FIGS. 6 to 8, the cross shaft universal joint is coupled to the ends of a pair of rotating shafts 50 and 52 disposed between a steering shaft (not shown) and a steering gear (not shown). A pair of yokes 54, 56 and a cross shaft 58 that couples the pair of yokes 54, 56 so as to be swingably displaceable are provided.

  One yoke 54 has a serrated 64 a formed on the inner peripheral surface of the cylinder, and a notched cylindrical hub 64 in which a slit 64 b is formed in the axial direction of the cylinder, and a position sandwiching the slit 62 of the hub 64. A pair of flanges 66 and 68 projecting in parallel, a bolt passage hole 70 and a screw hole 72 formed at positions corresponding to each other of the pair of flanges 66 and 68, and an axis from an axial end of the hub 64 along the axis. A pair of forks 76 and 78 having a bearing hole 74 that is formed in parallel and connects the cross shaft 58 is provided.

  A serration 50a is formed on the outer periphery of the end of the rotating shaft 50 to which one yoke 54 is coupled. The hub 64 of the yoke 54 is externally fitted on the outer periphery of the end of the rotating shaft 50, and the serration 64a of the hub 64 is attached. Then, the serration 50a of the rotary shaft 50 is serrated and fitted with a gap. Then, the fastening bolt 80 inserted into the bolt passage hole 70 of one flange 66 is screwed into the screw hole 72 of the other flange 68 and fastened to bring the pair of flanges 66 and 68 close to each other, and the serration 50a and the serration 64a. The yoke 54 is coupled to the rotary shaft 50 by reducing the inner diameter of the hub 64 so as to be in close contact with each other. The other yoke 56 is also coupled to the rotary shaft 52 with the same structure.

By the way, in recent years, a steering device including an electric power steering device that transmits a steering assist force to a steering gear has been developed, and high torque rotation is transmitted also to a steering shaft and a transmission path of the steering gear of the steering device. Therefore, the universal joint is required to have a strength capable of withstanding high torque rotation.
Here, when the fastening bolt 80 is strongly fastened when the yoke 54 is coupled to the rotating shaft 50 (the yoke 56 is connected to the rotating shaft 52), the pair of flanges 66 and 68 become non-parallel and the bending load is applied to the fastening bolt 80. Therefore, as shown in FIG. 7, the tightening bolt 80 is curved.

Further, when high torque rotation is transmitted between the yoke 54 and the rotary shaft 50, as shown in FIG. 8, the thrust load is alternately input to the pair of flanges 66 and 68, so that the repeated bending load is applied to the tightening bolt 80. Works.
In this way, the bending bolt 80 acts on the fastening bolt 80 as an average stress when the yoke 54 and the rotary shaft 50 (the yoke 56 and the rotary shaft 52) are coupled, and a high torque acts as a stress amplitude during the rotation. The fatigue strength of 80 may be reduced.

Here, as a structure for preventing a reduction in the strength of the tightening bolt, for example, as shown in Patent Document 1, a nut and a bolt screw that are engaged with the flange from the seating surface of the head of the tightening bolt when the yoke and the rotary shaft are coupled. A technique is known in which the degree to which the tightening bolt is bent (curvature) is reduced by setting the distance to the portion to a predetermined length.
Japanese Patent No. 3480109

However, although the technique described in Patent Document 1 reduces the degree of bending of the tightening bolt when the yoke and the rotating shaft are coupled, high torque rotation is transmitted between the yoke and the rotating shaft and between the yoke and the rotating shaft. When this is done, a bending load always acts on the tightening bolt, so it is impossible to prevent a decrease in the fatigue strength of the tightening bolt.
Therefore, the present invention has been made paying attention to the unsolved problems of the conventional example, and even when an electric power steering device that transmits a steering assist force to the steering gear is incorporated in the steering device, high torque rotation is transmitted. An object of the present invention is to provide a coupling structure of a yoke and a rotary shaft in a steering device that improves the fatigue strength of a universal joint.

  In order to achieve the above object, the coupling structure of the yoke and the rotating shaft in the steering device according to claim 1 is a notched cylindrical hub having a slit formed in the axial direction and a female serration formed on the inner peripheral surface; A yoke including a pair of flanges extending parallel to each other from a position where the slit of the hub is sandwiched and a pair of forks integrally formed on one end side in the axial direction of the hub is provided with a male serration on the outer periphery of the end portion. The inner diameter of the hub is such that the male serration and the female serration are in close contact with each other by fastening the bolts connected to the pair of flanges and fastening bolts connected to the pair of flanges. A bending load acting on the tightening bolt in the coupling structure of the yoke and the rotating shaft in the steering device that is reduced in diameter and coupled to the rotating shaft The bending load sharing member to share a part of, is provided between the pair of flanges.

According to a second aspect of the present invention, in the combined structure of the yoke and the rotary shaft in the steering device according to the first aspect, the bending load sharing member is press-fitted into a pin press-fit hole provided to face a pair of flanges. It is a press-fit pin.
Further, the invention according to claim 3 is the coupling structure of the yoke and the rotating shaft in the steering device according to claim 1, wherein the bending load sharing member is embedded in the slit and is joined to the inner walls of the pair of flanges by welding. This is a flange coupling member.

  According to the coupling structure of the yoke and the rotary shaft in the steering device of the present invention, even if the steering assist means for transmitting the steering assist force to the steering gear is incorporated in the steering device, the pair extending in parallel with each other from the position where the hub slit is sandwiched. When tightening the tightening bolts connected to the flange, the inner diameter of the hub is reduced so that the male serration of the rotating shaft and the female serration of the hub are brought into close contact with each other, and when coupled to the rotating shaft In addition, since a part of the bending load acting on the tightening bolt is shared by the bending load sharing member, even if a high torque rotation is transmitted between the yoke and the rotating shaft, the fatigue strength is improved and the yoke and the output shaft are securely connected. Can be combined.

Hereinafter, the best mode for carrying out the present invention (hereinafter referred to as an embodiment) will be described in detail with reference to the drawings.
1 to 4 are views showing a steering apparatus according to the present invention, FIG. 1 is an overall configuration diagram showing an embodiment of the present invention, and FIG. 2 is a universal joint of the first embodiment incorporated in the steering apparatus. FIG. 3 is a cross-sectional view taken along the line BB in FIG. 2, FIG. 4 is a view showing the coupling structure of the yoke and the rotary shaft of the first embodiment from a direction perpendicular to the axis of the tightening bolt, and FIG. It is the figure which showed the coupling structure of the yoke and rotating shaft of 2nd Embodiment from the direction orthogonal to the axis | shaft of a clamping bolt.

Reference numeral 2 in FIG. 1 denotes a steering shaft having a steering wheel 1 mounted on the vehicle rear end (right end in FIG. 1). The steering shaft 2 is disposed with an upward inclination toward the rear of the vehicle. The column 3 is rotatably held.
On the vehicle front end (left end in FIG. 1) side of the steering shaft 2, a worm speed reducer 11 that applies steering assist torque to the steering shaft 2 and an electric motor 12 that generates steering assist torque in the worm speed reducer 11 are configured. The steering assist mechanism 4 is connected.

The steering shaft 2 has an outer shaft 7 and an inner shaft 8, and a front end portion of the outer shaft 7 and a rear end portion of the inner shaft 8 are spline-coupled.
A cylindrical steering column 3 through which the steering shaft 2 is inserted is formed by combining an outer column 9 and an inner column 10 in a telescope shape, and is fitted so that its position can be adjusted in the axial direction.

  On the vehicle front side of the outer column 9, a clamp portion (not shown) separated in the vehicle width direction that holds the outer periphery of the inner column 10 is integrally formed, and this clamp portion is fixed to the vehicle body side member 16. The upper bracket 26 is sandwiched from the vehicle width direction. The upper bracket 26 is provided with a clamp device 27 that clamps the inner column 10 via a clamp portion.

Further, the housing 11a of the worm speed reducer 11 in the steering assist mechanism 4 is supported so as to be swingable in the vertical direction around a pivot pin 24 rotatably supported by a lower bracket 23 attached to the vehicle body side member 16. ing.
Then, the front end portion of the inner column 10 is fixed to the rear end surface of the housing 11a of the worm speed reducer 11, the inner shaft 8 is inserted into the housing 11a of the worm speed reducer 11, and the front end portion of the inner shaft 8 is The speed reducer 11 is connected to an output shaft 14 protruding from the front end surface of the housing 11a.

An intermediate shaft 18 is connected to the output shaft 14 of the worm reducer 11 via a universal joint 17A, and this intermediate shaft 18 is connected to a pinion shaft 19 of a rack and pinion type steering gear mechanism 6 via a universal joint 17B. Has been. The intermediate shaft 18 employs a telescopic shaft composed of a male shaft 18a and a female shaft 18b.
Although not shown, the steering gear mechanism 6 is configured in a rack-and-pinion type in which a pinion connected to a pinion shaft 19 and a rack shaft having a rack meshing with the pinion are arranged in a gear housing. Rotational motion transmitted to is converted to linear motion on the rack shaft. A rack shaft (not shown) is connected to a steered wheel (not shown) via a tie rod 5.

(First embodiment)
As shown in FIG. 2, the universal joint 17A of the first embodiment for connecting the output shaft 14 and the female shaft 18b of the intermediate shaft 18 includes a first yoke 30 coupled to the end of the output shaft 14 and the female shaft 18b. A second yoke 31 coupled to the end portion and a cross shaft 40 that couples the first and second yokes 30 and 31 so as to be swingably displaceable are provided.

The first yoke 30 includes a notched cylindrical hub 32 and a pair of forks 33 and 34 formed in parallel from the axial end of the hub 32 along the axis. As shown in FIG. 4, one fork 34 has a bearing hole 34 a for connecting the cross shaft 40. Although not shown, the other fork 33 also has a bearing hole for connecting the cross shaft 40.
As shown in FIG. 3, the hub 32 has a female serration 32a on the inner peripheral surface and a slit 32b in the axial direction. As shown in FIGS. 3 and 4, the slit 32b is formed with a first slit 32b1 having a large slit width on the end side, and a second slit 32b2 having a small slit width is formed from the first slit 32b1.

The hub 32 is formed with a pair of flanges 35 and 36 so as to be parallel to each other from a position sandwiching the slit 32b.
As shown in FIG. 4, a bolt passage hole 41 is formed in one flange 35 toward the second slit 32 b 2, and a screw hole 42 is formed in the other flange 36 at a position facing the bolt passage hole 41. Is formed. In addition, a first pin press-fit hole 37a penetrating toward the first slit 32b1 is formed in one flange 35, and the same diameter is provided at a position corresponding to the first pin press-fit hole 37a of the other flange 36. A second pin press-fitting hole 37b is formed.

Further, as shown in FIG. 3, a male serration 14 a is formed on the outer periphery of the end portion of the output shaft 14.
Here, the outer diameter dimension of the male serration 14a of the output shaft 14 is smaller than the inner diameter dimension of the female serration 32a of the hub 32, and the inner diameter dimension of the male serration 14a of the output shaft 14 is smaller than the outer diameter dimension of the female serration 32a of the hub 32. Is set.

  Then, the fastening bolt 38 is inserted into the bolt passage hole 41 of one flange 35, and the screw portion of the fastening bolt 38 is screwed into the screw hole 42 of the other flange 36 to fasten the pair of flanges 35, 36 to each other. The first yoke 30 is coupled to the output shaft 14 by reducing the inner diameter of the hub 32 so that the male serration 14a and the female serration 32a are in close contact with each other.

Further, the press-fit pin 43 is press-fitted into the first pin press-fit hole 37 a of the one flange 35 and the second pin press-fit hole 37 b of the other flange 36 facing each other.
The second yoke 31 coupled to the end of the female shaft 18b is also coupled with the same structure as the first yoke 30 coupled to the end of the output shaft 14 described above.
Here, the slit according to the present invention corresponds to the first slit 32b1, the rotation shaft according to the present invention corresponds to the output shaft 14, and the pin press-fitting hole of the present invention corresponds to the first pin press-fitting hole 37a and the second pin press-fitting hole 37b. It corresponds.

Next, the effect of this embodiment will be described.
In this embodiment, when the tightening bolt 38 is tightened to couple the first yoke 30 to the output shaft 14, the pair of flanges 35 and 36 become non-parallel and a bending load acts on the tightening bolt 38.
When the pair of flanges 35 and 36 are in a non-parallel state, as shown in FIG. 3, the press-fit pins press-fitted into the first pin press-fit hole 37 a of one flange 35 and the second pin press-fit hole 37 b of the other flange 36. 43 also shares a bending load acting on the tightening bolt 38 while curving.

In addition, when high torque rotation is input from the steering assist mechanism 4 to the output shaft 14, a repeated bending load is applied by the thrust load input to the pair of flanges 35 and 36. The press-fit pins 43 connected between the flanges 35 and 36 share a repeated bending load acting on the tightening bolt 38 while being curved.
Therefore, in this embodiment, even if the steering assist mechanism 4 that transmits the steering assist force to the steering gear mechanism 6 is incorporated in the steering device, the bending load acting on the tightening bolt 38 is press-fitted between the pair of flanges 35 and 36. Since the pins 43 share the fatigue strength of the universal joint 17A that transmits high-torque rotation, the first yoke and the output shaft 14 can be reliably coupled.

In addition, when high torque rotation is input from the steering assist mechanism 4 to the output shaft 14, the press-fit pin 43 that shares the bending load of the tightening bolt 38 has a curved shape, and thus the first pin press-fit hole. There is no fear of dropping from the 37a and the second pin press-fitting hole 37b.
Further, since the second yoke 31 is also coupled to the female shaft 18b with the same structure as the coupling of the first yoke 30 and the output shaft 14, the same effect as the coupling structure of the first yoke 30 and the output shaft 14 is obtained. A coupling structure of the second yoke 31 and the female shaft 18b can also be obtained.

(Second Embodiment)
Next, FIG. 5 shows a coupling structure of a yoke and a rotary shaft according to the second embodiment of the present invention. In addition, the same code | symbol is attached | subjected to the same component as 1st Embodiment shown in FIGS. 1-4, and the description is abbreviate | omitted.
In the present embodiment, the first pin press-fit hole 37a as in the first embodiment is not formed in one flange 35, and the second pin press-fit hole 37b is not formed in the other flange 36. The flange coupling member 44 is embedded in the first slit 32b1 extending in the axial direction between the flanges 35 and 36, and the flange coupling member 44 is coupled to the inner walls of the pair of flanges 35 and 36 by welding.

Here, the slit of the present invention corresponds to the first slit 32 b 1, and the rotating shaft of the present invention corresponds to the output shaft 14.
Also in this embodiment, when the clamping bolt 38 is tightened to couple the first yoke 30 to the output shaft 14, the pair of flanges 35 and 36 become non-parallel and a bending load acts on the clamping bolt 38. A flange coupling member 44 embedded in one slit 32b1 and coupled to the inner walls of the pair of flanges 35 and 36 by welding shares a bending load acting on the tightening bolt 38.

Further, when a high torque rotation is input from the steering assist mechanism 4 to the output shaft 14, the flange coupling member 44 also shares a repeated bending load that acts on the tightening bolt 38 due to a thrust load input to the pair of flanges 35 and 36. .
Therefore, in this embodiment, even if the steering assist mechanism 4 for transmitting the steering assist force to the steering gear mechanism 6 is incorporated in the steering device, the bending load acting on the tightening bolt 38 is fixed between the pair of flanges 35 and 36. Since the coupling member 44 shares the fatigue strength of the universal joint 17A that transmits high torque rotation, the first yoke and the output shaft 14 can be reliably coupled.

Although not shown, when the second yoke 31 is coupled to the female shaft 18b with the same structure as the coupling of the first yoke 30 and the output shaft 14 of the present embodiment, the second yoke 31 is coupled to the first yoke 30 of the present embodiment. The same effect as the coupling structure of the output shaft 14 can be obtained by the coupling structure of the second yoke 31 and the female shaft 18b.
The same effect can be obtained if the universal joint 17B that connects the male shaft 18a of the intermediate shaft 18 and the pinion shaft 19 of the steering gear mechanism 6 has the same coupling structure as the above-described universal joint 17A.

  In the above embodiment, the bolt passage hole 41 is formed in one flange 35 and the screw hole 42 is formed in the other flange 36. However, the screw hole is formed in one flange 35 and the screw of the other flange 36 is screwed. The bolt passage hole 41 may be formed at a position corresponding to the hole, and the tightening bolt 38 may be screwed.

1 is an overall configuration diagram showing an embodiment of a steering device according to the present invention. It is a figure which shows the universal joint of 1st Embodiment integrated in the steering apparatus. It is a BB arrow sectional view of Drawing 2. It is the figure which showed the coupling structure of the yoke and rotating shaft of 1st Embodiment from the direction orthogonal to the axis | shaft of a clamping bolt. It is the figure which showed the coupling structure of the yoke and rotating shaft of 2nd Embodiment from the direction orthogonal to the axis | shaft of a clamping bolt. It is a figure which shows the conventional universal joint integrated in the steering apparatus. It is an AA arrow directional view of FIG. It is a figure which shows the external force input into a yoke when rotation of a high torque is transmitted to the conventional universal joint.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Steering wheel, 2 ... Steering shaft, 3 ... Steering column, 4 ... Steering assistance mechanism, 5 ... Tie rod, 6 ... Steering gear mechanism, 7 ... Outer shaft, 8 ... Inner shaft, 9 ... Outer column, 10 ... Inner column 11 ... Worm reducer, 11a ... Housing, 12 ... Electric motor, 14 ... Output shaft, 14a ... Male serration, 16 ... Body member, 17A ... Universal joint, 17B ... Universal joint, 18 ... Intermediate shaft, 18a ... Male Shaft, 18b ... Female shaft, 19 ... Pinion shaft, 23 ... Lower bracket, 24 ... Pivot pin, 26 ... Upper bracket, 27 ... Clamp device, 30 ... First yoke, 31 ... Second yoke, 32 ... Hub, 32a ... Female serration, 32b ... slit, 32b1 ... first slit, 32b2 ... second slit, 33, 34 Fork, 34a ... bearing hole, 35, 36 ... flange, 37a ... first pin press-fit hole, 37b ... second pin press-fit hole, 38 ... tightening bolt, 40 ... cross shaft, 41 ... bolt passage hole, 42 ... screw hole, 43 ... Press-fit pin, 44 ... Flange coupling member

Claims (3)

A notched cylindrical hub having a slit formed in the axial direction and a female serration on the inner peripheral surface, a pair of flanges extending parallel to each other from a position across the slit of the hub, and a shaft of the hub A yoke provided with a pair of forks formed integrally on one end side in the direction is serrated to a rotating shaft having male serrations on the outer periphery of the end portion, and fastening bolts connected to the pair of flanges are fastened. In the coupling structure of the yoke and the rotary shaft in the steering device, the inner diameter of the hub is reduced so that the male serration and the female serration are in close contact with each other and the pair of flanges are in close contact with each other.
A coupling structure of a yoke and a rotary shaft in a steering device, wherein a bending load sharing member for sharing a part of a bending load acting on the tightening bolt is provided between the pair of flanges.   2. The coupling structure of a yoke and a rotary shaft in a steering apparatus according to claim 1, wherein the bending load sharing member is a press-fit pin that is press-fitted into a pin press-fit hole provided to face a pair of flanges.   2. The coupling of a yoke and a rotating shaft in a steering apparatus according to claim 1, wherein the bending load sharing member is a flange coupling member embedded in the slit and coupled to the inner walls of the pair of flanges by welding. Construction.

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