JP3756022B2 - Collapsible shaft - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a collapsible shaft that absorbs an impact by contracting when a strong impact is applied due to a collision in a steering apparatus of an automobile.
[0002]
[Prior art]
In an automobile steering device, for example, the movement of a steering wheel is transmitted to a steering gear via a steering shaft and an intermediate shaft connected thereto, and the wheel is steered by the steering gear.
In order to absorb the impact at the time of a collision, the above-described steering shaft or intermediate shaft is generally a collapsible shaft whose overall length is shortened when an impact is applied.
[0003]
For example, as the above-described collapsible shaft, one applied to a steering shaft is disclosed in JP-A-10-030669. That is, the collapsible shaft has a shaft and a tube that is arranged coaxially with the shaft and into which the end of the shaft is inserted, and pushes the inclined side surface of the shaft into the tube to expand the tube. The shock is absorbed. In a state before shock absorption, the shaft includes an insertion portion inserted into the tube from the open end of the tube. A substantially V-shaped notch is formed at the open end of the tube. This notch is for suppressing a peak at the time of rising of the impact force so as to reduce the impact force when the driver hits the steering wheel. In the state before absorbing the shock, the cut tip of the notch does not reach the tip of the insertion portion of the shaft.
[0004]
When an impact is applied to the collapsible shaft described above, the shaft expands and pushes the tube into the back, while expanding the notch by the inclined side surface to form a tear extending from the notch tip of the notch.
[0005]
[Problems to be solved by the invention]
When the shaft penetrates, the tube is torn to both sides at the tip position of the notch. Therefore, with a small force, the shaft cannot be pushed deep into the tube, and the shock absorption stroke amount may be short and insufficient.
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a collapsible shaft that solves the above technical problem and can reliably obtain a sufficient shock absorbing stroke amount.
[0006]
[Means for Solving the Problems and Effects of the Invention]
The invention according to claim 1 is a collapsible shaft for a steering device that absorbs an impact by pushing the inclined side surface of the shaft into the tube and expanding the tube, and the collapsible shaft is arranged as an intermediate shaft. The shaft constitutes the lower part of the intermediate shaft, the tube constitutes the upper part of the intermediate shaft , and the shaft is inserted into the tube from the open end of the tube in a state before shock absorption. The tube is welded so that a slit extending in the axial direction from the open end of the tube is formed over the entire length of the tube and a part of the slit is closed in the middle of the tube in the axial direction. and a weld seen including, with respect to the axial direction of the tube, welding The have left the open portion of the slits on both sides, when the shock absorbing, with the pushing of the shaft into the tube, Korapu steering apparatus characterized by are as slit is pushed open Provide a sibling shaft.
[0007]
According to the present invention, since the slit is deeper than the tip end position of the shaft, when the shaft is pushed inward, the inside of the tube is easily expanded, so that the pushing force of the shaft is small. Therefore, even with a small pushing force, the shaft can be pushed deep into the tube according to the slit, so that the shock absorbing stroke amount of the collapsible shaft can be sufficiently secured .
[0008]
When absorbing the impact, the shaft can be pushed deeply into the tube.
In addition, since the tube having the slit extending over the entire length can be formed by, for example, winding a flat plate in an arc shape, it is possible to save the trouble of cutting the slit in the pipe.
According to a second aspect of the present invention, there is provided the collapsible shaft for a steering apparatus according to the first aspect, wherein the slit extends in a crank shape while being bent in a zigzag manner. .
The invention according to claim 3 is a collapsible shaft for a steering device that absorbs an impact by pushing the inclined side surface of the shaft into the tube and expanding the tube, and the tube has a pair of end portions in the circumferential direction. The pair of ends are stacked in the radial direction of the tube, and when absorbing the shock, the pair of stacked ends are pushed into the tube, and the inclined side surface of the shaft. The present invention provides a collapsible shaft for a steering device, which is characterized in that it can be pushed and expanded .
[0009]
According to the present invention, the tube having a pair of end portions in the circumferential direction can easily expand over its entire length when the shaft is pushed in, so that a sufficient shock absorbing stroke amount can be ensured.
In addition, since the pair of end portions in the circumferential direction of the tube are stacked on each other , the rigidity of the tube can be increased. As a result, it is possible to make rattling difficult during steering operation.
[0010]
Further, it is possible to eliminate the need for slit cutting when forming the tube.
A fourth aspect of the present invention is the collapsible shaft for a steering device according to the first or second aspect , wherein the shaft is connected to a tube by a serration joint structure. I will provide a.
The invention described in claim 5, in the steering device for a collapsible shaft according to any one of claims 1 to 4, said tube is a steering device characterized by comprising formed by winding a flat plate Provide collapsible shaft.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a steering apparatus according to an embodiment of the present invention will be described. FIG. 1 is a perspective view of the steering device.
The steering device 1 transmits the movement of the steering wheel 2 to a steering gear (not shown) via a steering shaft 4 inserted inside the steering column 3 and an intermediate shaft 5 connected thereto. A wheel (not shown) is steered by this steering gear. The steering gear is accommodated in a gear box 6, and a support shaft 7 connected to the steering gear extends from the gear box 6. The upper end portion of the support shaft 7 and the lower end portion of the intermediate shaft 5 are connected via a universal joint 8, and the upper end portion of the intermediate shaft 5 and the lower end portion of the steering shaft 4 are connected via a universal joint 9. Has been.
[0012]
In the present embodiment, the intermediate shaft 5 is a collapsible shaft 10 corresponding to the impact on the primary side as will be described later. Reference is made to the cross-sectional view of FIG.
The collapsible shaft 10 includes a tube 12 and a shaft 11 that are coaxially connected to each other, and an end portion of the shaft 11 is inserted into an end portion of the tube 12. In a state before shock absorption, the shaft 11 extends from the tube 12, and the tube 12 and the shaft 11 are coupled so as to be integrally rotatable. When an impact is applied, the shaft 11 enters the tube 12, whereby the collapsible shaft 10 is contracted and the axial length is shortened. Then, the impact is absorbed by pushing the inclined side surface 13 of the shaft 11 into the tube 12 and expanding the tube 12.
[0013]
A shaft 11 of the collapsible shaft 10 constitutes a lower portion of the intermediate shaft 5. A bifurcated fork portion 21 which is a part of the universal joint 8 is formed integrally with the lower portion of the shaft 11. Moreover, the tube 12 comprises the upper part of the intermediate shaft 5, and the lower end part of the universal joint 9 is connected with the upper end.
Details will be described below.
[0014]
The shaft 11 includes the fork portion 21 described above, an inclined surface forming portion 22 that forms the inclined side surface 13, and an insertion portion 14 that is inserted into the tube 12, and the fork portion 21, the inclined surface forming portion 22, and the like. Each part with the insertion part 14 is lined up along the axial direction in order.
The surface of the fork portion 21 and the inclined side surface 13 are smoothly connected to each other, and a protrusion or the like is not formed on each surface so that the shaft 11 does not hinder the entry into the tube 12.
[0015]
The inclined side surface 13 is adjacent to the insertion portion 14 and is smoothly connected to the outer peripheral surface 15 of the insertion portion 14. The inclined side surface 13 is formed of a tapered surface that increases in the radial direction as the distance from the insertion portion 14 increases. When an impact is applied, the inner peripheral surface 16 of the tube 12 moves along the inclined side surface 13 in the axial direction. Along with this, the tube 12 is expanded.
The insertion portion 14 is formed in a substantially cylindrical shape with a predetermined length. Numerous irregularities extending in the axial direction are formed on the outer peripheral surface of the insertion portion 14, and numerous irregularities extending in the axial direction are also formed on the inner circumferential surface 16 of the tube 12 so as to face these irregularities. The outer peripheral surface of the insertion portion 14 and the inner peripheral surface 16 of the tube 12 are connected to each other by a so-called serration joint structure in which the opposing concave and convex portions and the unevenness are engaged with each other. Further, the insertion portion 14 is fitted into the inner peripheral surface 16 in a press-fit state, and receives a binding force so as to be tightened from the outside by the tube 12. By applying this binding force, the tube 12 and the shaft 11 are prevented from being relatively displaced in the axial direction with respect to an axial force of such a magnitude in a normal use state, and when torque is applied. However, the tube 12 does not expand.
[0016]
The tube 12 is formed in a circular arc shape having an end in the circumferential direction (see FIG. 3), and has the same cross-sectional shape in the axial direction. The length of the tube 12 is set longer than that of the shaft 11, for example, so as to obtain a required shock absorbing stroke amount. The tube 12 has a linear slit 19 that extends in the axial direction from the opening end 17 beyond the position where the distal end 18 of the insertion portion 14 is located (before the impact is applied) and reaches the other end 23. .
[0017]
The slit 19 is formed as a single piece with a predetermined width between the arc ends 20 as a pair of ends in the circumferential direction of the tube 12 as viewed from the axial direction.
In the vicinity of the open end 17 of the tube 12, the inner peripheral surface 16 smoothly spreads in the radial direction, and the inclined side surface 13 of the shaft 11 can be smoothly introduced at the time of impact.
In this collapsible shaft 10, the insertion portion 14 of the shaft 11 is inserted into the tube 12 in a state before shock absorption, which is a normal use state, as shown in FIG. Extends outwardly from the open end 17 of the tube 12. In this state, the shaft 11 and the tube 12 rotate integrally so as to transmit torque without being relatively displaced in the axial direction.
[0018]
When an impact is applied, a greater axial force is applied than during normal use. At this time, the shaft 11 is pushed into the tube 12 as shown in FIG. The inclined side surface 13 enters the inside from the open end 17 of the tube 12, and the tube 12 smoothly expands radially outward along the inclined side surface 13, thereby absorbing the impact. . Further, the insertion portion 14 of the shaft 11 expands the tube 12 against the binding force of the tube 12 and relatively displaces while rubbing the inner peripheral surface 16 of the tube 12, thereby absorbing the impact.
[0019]
As the shaft 11 is pushed into the tube 12, the width of the slit 19 increases and the circumferential deformation of the tube 12 is absorbed. The shaft 11 reaches deeper on the other end side which is the upper end of the tube 12.
As described above, according to the present embodiment, the slit 19 reaches deeper than the position of the tip 18 of the shaft 11 before absorbing the shock, and therefore, when the shaft 11 is pushed deeper than the position of the tip 18. In addition, the inside of the tube 12 is easily expanded. As a result, the pushing force of the shaft 11 can be small. Therefore, even if the force applied at the time of impact is relatively small, the shaft 11 is pushed deep into the tube 12 according to the length of the slit 19, so that the impact of the collapsible shaft 10 that is the pushing amount of the shaft 11. A sufficient amount of absorption stroke can be secured. Therefore, it is preferable for the impact absorption on the primary side, which will be described later, to obtain a sufficient stroke amount with certainty.
[0020]
In particular, since the slit 19 extends over the entire length of the tube 12, the shaft 11 can be reliably pushed deep into the tube 12 when absorbing the impact. For example, in the collapsible shaft 10 of the present embodiment, the amount of shock absorption stroke can be approximately 80% of the total length of the collapsible shaft 10. The reason why the shock absorbing stroke amount does not become 100% of the total length is that the shaft 11 remains without being deformed by the impact.
[0021]
Moreover, since the tube 12 having the slit 19 extending over the entire length can be formed by, for example, winding a flat plate in an arc shape, it is possible to save the trouble of cutting the slit in the pipe.
By the way, the impact at the time of the collision includes a primary side impact that acts from the steering gear side member toward the steering wheel due to the collision, and a secondary side that occurs when the driver collides with the steering wheel due to the reaction of the collision. There is an impact, and each collapsible shaft receives each impact.
[0022]
The collapsible shaft against the impact on the primary side absorbs the amount of movement of the engine of the vehicle at the time of collision (this amount of movement is normally set long), and the steering wheel moves toward the driver in the vehicle interior. Since it is necessary not to protrude, there is a demand for securing the shock absorbing stroke amount as long as possible.
Moreover, the collapsible shaft against the impact on the secondary side absorbs a large collision energy and prevents the driver from applying a large impact force, and it is necessary to achieve these matters with a short shock absorption stroke amount. . This is because if the shock absorbing stroke amount becomes too long, it is assumed that the driver collides with a vehicle interior portion other than the steering device.
[0023]
Here, as the collapsible shaft on the secondary side, the collapsible shaft described in the above-mentioned section of the prior art can be exemplified, but as described above, the required shock absorption characteristics on the primary side and the secondary side Therefore, the secondary side structure cannot be applied to the primary side. On the other hand, the collapsible shaft 10 of the present embodiment is suitable for primary side shock absorption because a sufficient amount of shock absorption stroke can be reliably obtained.
[0024]
The width of the slit 19 is not particularly limited. For example, the circular arc ends 20 forming the slits 19 may be opposed to and substantially in contact with the shaft 11 being press-fitted.
Further, the slit 19 may be one that extends in a straight line shape in the axial direction, for example, one that extends while being bent in a zigzag shape in a crank shape.
Further, the slit 19 may be formed to extend from the opening end 17 of the tube 12 to the middle portion of the tube 12 with a predetermined length shorter than the entire length of the tube 12 in the axial direction. In this case, the shock absorbing stroke amount of the collapsible shaft 10 for a small load can be set according to the predetermined length of the slit 19. Moreover, since the arc ends 20 are connected to each other in the vicinity of the end portion on the back side of the slit 19 and the tube 12 becomes cylindrical, the rigidity of the tube 12 can be increased as compared with the case where the slit 19 extends over the entire length.
[0025]
For example, the slit 19 having an end on the back side may be formed by cutting a notch portion extending from the opening end 17 by a predetermined length on the circumferential surface of a tube made of a cylinder. In addition, as shown in FIG. 4, a part of the slit 19 extending over the entire length of the tube 12 having a circular arc cross section is fixed by a welded portion 24 . The welded portion 24 is located at a predetermined distance from the opening end 17 in the axial direction, and connects the opposing arc ends 20 to each other.
A plurality of slits 19 may be provided as long as they extend to the middle portion in the axial direction.
[0026]
In short, the slit 19 may extend in the axial direction beyond the position where the tip 18 of the insertion portion 14 of the shaft 11 is in a state before absorbing the shock.
Moreover, as shown in FIGS. 5 and 6, the arc ends 20 of the tube 12 may overlap each other. In the overlapping portion, the inner peripheral surface in the vicinity of the arc end 20 on the outer side in the radial direction is in contact with the outer peripheral surface in the vicinity of the arc end 20 on the inner side in the radial direction. The pressing force is applied inward in the radial direction. Further, the overlapping portion extends over the entire length of the tube 12 and is provided only in a part in the circumferential direction, for example, in a region that is approximately half or less of the circumferential length.
[0027]
The tube 12 having a circular arc cross section is easy to expand over the entire length when the shaft 11 is pushed in, compared to a tube made of a cylinder, so that a sufficient shock absorbing stroke amount can be secured. For example, in the tube 12 having a circular arc cross section in which the arc ends 20 are overlapped with each other, the shock absorbing stroke amount can be ensured as in the case where the slit 19 is formed over the entire length of the tube 12.
In addition, since the arc ends 20 of the tube 12 overlap each other, the rigidity of the tube 12 can be increased while ensuring the ease of expansion in the radial direction of the tube 12 as compared with the case where the slit 19 is formed. . As a result, it is possible to make rattling difficult during steering operation.
[0028]
Further, in the overlapping portions, the arc end 20 on the outer side in the radial direction and the outer peripheral surface of the vicinity of the arc end 20 on the inner side in the radial direction have a predetermined length in the axial direction from the opening end 17. It may be fixed by welding in the vicinity of a position separated from each other (the welded portion 24 by this is shown by a one-dot chain line in FIG. 5). In this case, it can be easily expanded like the tube 12 having the slit 19 having a predetermined length, and the rigidity can be further increased as compared with the case where welding is not performed.
[0029]
In addition, in the tube 12 having a circular arc cross section in which the arc ends 20 are overlapped with each other, it is not necessary to perform a cutting process for forming a slit in forming the tube 12, and a flat plate can be easily formed by winding it in an arc shape. .
Further, the configuration of the inclined side surface 13 of the shaft 11 is not limited to that described above. For example, the inclined side surface 13 may be disposed in the tube 12 before being deformed by an impact, or the insertion portion 14 may function as the inclined side surface 13.
[0030]
In the collapsible shaft 10 described above, the shaft 11 is disposed on the steering gear side and the tube 12 is disposed on the steering wheel side. However, the reverse may be reversed.
In addition, various design changes can be made without changing the gist of the present invention.
[Brief description of the drawings]
FIG. 1 is a perspective view of a steering apparatus including a collapsible shaft according to a first embodiment of the present invention.
FIG. 2 is a partial cross-sectional side view of the collapsible shaft of FIG. 1, wherein (a) shows a state before deformation, and (b) shows a state in which it is deformed by receiving an impact.
3 is a cross-sectional view of the tube of the collapsible shaft of FIG. 1, showing a cross section AA of FIG.
4 is a partial cross-sectional side view of the tube of the collapsible shaft of FIG . 1. FIG.
FIG. 5 is a partial sectional side view of a tube of a collapsible shaft showing a second embodiment of the present invention.
6 is a cross-sectional view of the tube of the collapsible shaft shown in FIG. 5 and shows a cross section taken along the line BB of FIG.
[Explanation of symbols]
5 Intermediate shaft 10 Collapsible shaft 11 Shaft (lower part)
12 Tube (upper part)
13 Inclined side face 14 Insertion part 17 Open end 19 Slit 20 Arc end (end part)
24 welds

Claims (5)

In a collapsible shaft for a steering device that absorbs an impact by pushing the inclined side surface of the shaft into the tube and expanding the tube,
This collapsible shaft is arranged as an intermediate shaft,
The shaft constitutes the lower part of the intermediate shaft, the tube constitutes the upper part of the intermediate shaft,
In a state before shock absorption, the shaft includes an insertion portion inserted into the tube from the open end of the tube, and the tube extends in the axial direction from the open end and is a slit formed over the entire length of the tube. When, seen including a welding unit for welding to close a portion of the slit in the middle portion in the axial direction of the tube, in the axial direction of the tube, which remains an open portion of the slits on both sides of the weld,
A collapsible shaft for a steering device , wherein a slit is pushed and expanded as the shaft is pushed into the tube when absorbing a shock . The collapsible shaft for a steering device according to claim 1,
A collapsible shaft for a steering device, wherein the slit extends in a crank shape while being bent in a zigzag manner. In a collapsible shaft for a steering device that absorbs an impact by pushing the inclined side surface of the shaft into the tube and expanding the tube,
The tube has a pair of end portions in the circumferential direction, and the pair of end portions are stacked on each other in the radial direction of the tube ,
A collapsible shaft for a steering device , wherein when absorbing an impact, the pair of end portions stacked on each other are expanded by the inclined side surface of the shaft pushed into the tube . The collapsible shaft for a steering device according to claim 1 or 2 ,
A collapsible shaft for a steering device, wherein the shaft is connected to a tube by a serration joint structure. The steering device for a collapsible shaft according to any one of claims 1 to 4,
A collapsible shaft for a steering device, wherein the tube is formed by winding a flat plate.

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