JP2001122132A - Impact absorbing type steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To adjust a contraction load to a desired value for improving protection of a driver. SOLUTION: An impact absorbing member 28 is externally fitted on an intermediate part of a male serration 17a formed on an inner shaft 13a. When a steering shaft 11a contracts in association with a collisional accident, one end rim of an outer shaft 12a and one end rim of the impact absorbing member 28 abut to each other, and the impact absorbing member 28 is displaced along with the outer shaft 12a. The contraction load is adjusted to the desired value by adjusting a fitting strength or a fitting position of the impact absorbing member 28.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shock-absorbing steering apparatus which contracts its entire length in the event of a collision to protect the life of a driver colliding with a steering wheel.

[0002]

2. Description of the Related Art In a vehicle steering system, a transmission mechanism as shown in FIG. 9 is used to transmit the movement of a steering wheel to a steering gear. As shown in FIG. 9, the rear end of the first steering shaft 1 (FIG. 9)
The steering wheel 2 is fixed to the right end of the steering wheel 2). The steering column 3 is fixed to the vehicle body on the lower surface of the instrument panel 6 by means of rear and front brackets 4 and 5. The first steering shaft 1 is provided inside the steering column 3,
It is inserted rotatably. A portion of the front end of the first steering shaft 1 (the left end in FIG. 9) protruding from the front end opening of the steering column 3 is connected to the second steering shaft 8 via the first universal joint 7. It is connected to the rear end. Further, the front end of the second steering shaft 8 is connected via a second universal joint 9 to a third steering shaft 10 communicating with a steering gear (not shown).

[0003] Since the transmission mechanism of the vehicle steering system is constructed as described above, the movement of the steering wheel 2 is as follows.
The power is transmitted to the steering gear via the first steering shaft 1, the first universal joint 7, the second steering shaft 8, the second universal joint 9, and the third steering shaft 10 through which the steering column 3 is inserted. . Then, the steering gear gives a steering angle corresponding to the movement of the steering wheel 2 to the wheels.

[0004] In the steering apparatus for an automobile constructed as described above, the steering column 3 and each of the steering shafts 1 and 8 are provided to protect the driver in the event of a collision.
It is common practice to use a shock-absorbing type in which the overall length shrinks with the impact. Conventionally, as a steering shaft constituting such a shock absorbing type steering apparatus, for example, Japanese Patent Application Laid-Open Nos.
JP-A-267753, JP-A-9-267754, JP-A-9-272247, JP-B-47-46092, JP-A-1-58373, JP-A-5-35542, JP-A-5-37642, and JP-A-5-37642. No. 6-8150, Japanese Utility Model Publication No. 57-16773, and No. 58-5109.
No. 6 is known. However, any of the steering shafts described in these publications has a contraction amount (a collapse amount) of the steering shaft.
With the increase of the steering shaft, it is difficult to gradually increase the contraction load (collapse load) required to shorten the entire length of the steering shaft, and it may not always be possible to sufficiently protect the driver.

In view of the above circumstances, Japanese Unexamined Utility Model Publication No. 5-37642 discloses a steering shaft having a structure as shown in FIG. 10 as a steering shaft for gradually increasing the collapse load. In the steering shaft 11 described in this publication, an impact load in the axial direction is applied by combining the outer shaft 12 and the inner shaft 13 so as to be relatively displaceable in the axial direction (the left-right direction in FIG. 10). In such a case, the overall length is shortened in the event of a failure. The outer shaft 12 has a cylindrical shape as a whole, and a female serration 15 is formed on the inner peripheral surface of the front end (the left end in FIG. 10) which is one end. The inner shaft 13 also has a circular tubular shape as a whole, and is engaged with a female serration 15 formed on the inner peripheral surface of the outer shaft 12 at a rear end (right end in FIG. 10) which is also one end. , Male serrations 17 are formed.

Further, protrusions 16 and 16 are formed at two positions axially separated from each other at a part of the bottom of the valley 14 of the male serration 17. Each of these projections 16, 16
Are the outer shaft 12 and the inner shaft 13
When the male serration 17 is inserted into the female serration 15 so as to form the steering shaft 11 by combining the outer shaft 12 and the inner shaft 13, the male serration 17 comes into strong contact with the crest of the female serration 15.
Are prevented from displacing each other in the axial direction, and these two shafts 12, 13 are connected to each other.

The front end (left end in FIG. 10) of the male serration 17 on the outer peripheral surface of the inner shaft 13 has
A protrusion 19 having a height larger than the protrusions 16 is formed. The convex portion 19 is exposed outside the outer shaft 12 in a normal state (when there is no collision), but when the entire length of the steering shaft 11 is reduced due to a collision accident, the inner peripheral surface of the outer shaft 12 is reduced. Of the female serrations 15 of the steering shaft 11 to reduce the overall length of the steering shaft 11.

The operation of the steering shaft 11 configured as described above is as follows. First, at normal times, based on serration engagement between the inner peripheral surface of the front end of the outer shaft 12 and the outer peripheral surface of the rear end of the inner shaft 13,
The torque is transmitted between the shafts 12 and 13. In such a normal state, the projections 16 and 16 are strongly in contact with the crests of the female serrations 15, so that the entire length of the steering shaft 11 does not inadvertently shrink.

When a shocking load is applied in the axial direction at the time of a collision (primary collision or secondary collision), each of the protrusions 16,
16 plastically deforms the crests of the female serrations 15 to form the outer shaft 12 and the inner shaft 13.
, And the overall length of the steering shaft 11 is reduced. Further, when the front edge of the outer shaft 12 reaches the convex portion 19, the convex portion 19 engages with the crest of the female serration 15, and the top of the crest of the female serration 15 is plastically deformed while the steering is performed. The shaft 11 contracts. Therefore, the steering shaft 1
The shrinkage load increases as the amount of shrinkage increases.

The steering shaft 11 shown in FIG.
In the case of (1), the shrinkage load can be increased with an increase in the amount of shrinkage, so that protection of the driver can be enhanced. That is, when the contraction load of the steering shaft is small, the steering shaft easily contracts and cuts (full collapse), and at the moment when the steering shaft is completely contracted, that is, at the time of bottom striking, a great impact may be applied to the driver's body. Conversely, if the contraction load is increased in order to prevent a bottom bump, there is a possibility that an excessive impact is applied to the driver's body before the steering shaft is fully contracted. In order to prevent a large impact from being applied to the driver's body due to such factors, it is preferable to adjust the contraction load of the steering shaft so that it is small in the initial stage and increases with the increase in the contraction amount. . Due to such preferable characteristics, the steering shaft 11 as shown in FIG. 10 can prevent a large impact from being applied to the driver's body due to the above-described causes.

[0011]

However, in the case of the steering shaft 11 shown in FIG. 10, when the convex portion 19 and the female serration 15 are plastically deformed, the plastically deformed portion may cause gnawing or galling. Can occur. When such whirling or galling occurs, the contraction load does not increase stably, and it may be difficult to adjust the relationship between the amount of contraction and the contraction load as desired. The shock absorbing steering device of the present invention has been invented in view of such circumstances.

[0012]

The shock absorbing steering apparatus of the present invention includes an outer member formed in a cylindrical shape, and an inner member having one end inserted inside one end of the outer member. And, when a large axial load is applied between the outer member and the inner member, an impact absorbing portion that allows the axial dimension to contract freely by relative displacement in the axial direction between the outer member and the inner member. Provided. In particular, in the shock-absorbing steering device of the present invention, the shock-absorbing portion is provided on the outer peripheral surface of the inner member, usually at a position separated from one end edge of the outer member, and at the time of a collision accident. The apparatus includes at least one shock absorbing member externally fitted at a position where one end edge of the outer member is displaced when the device is contracted. Then, the shock absorbing member, together with the outer member while being pressed by the outer member, with the contraction of the shock absorbing steering device,
Displaced relative to the inner member.

[0013]

In the shock absorbing steering apparatus of the present invention constructed as described above, the shrinkage of the shock absorbing steering apparatus causes the shock absorbing member to be pressed by the outer member and the inner member together with the outer member. Displaces relative to the member. That is, in the shock absorbing steering device, the contraction load increases due to the resistance based on the friction of the fitting portion between the shock absorbing member and the inner member. Therefore, by adjusting the fitting strength and the fitting position of the shock absorbing member, the relationship between the amount of contraction and the contraction load can be adjusted as desired. Further, when a plurality of shock absorbing members are externally fitted to the inner member while being spaced apart from each other in the axial direction, the contraction load can be sequentially increased in three or more stages. Further, when a plurality of shock absorbing members are externally fitted to the inner member as described above, the fitting strength of each of the shock absorbing members is reduced to prevent a sudden increase in the shrinkage load, and to prevent the shock absorbing member from suddenly increasing. It can be adjusted so that the shrinkage load does not become too small. Therefore, it is easy to adjust the contraction load of the steering device to be small in the initial stage and to gradually increase as the contraction amount increases, and excessive impact is applied to the driver's body in the event of a collision accident. Can be prevented.

[0014]

1 to 4 show a first embodiment of the present invention. FIG. 1 shows a rear part of a vehicle steering system incorporating the shock absorbing steering apparatus of the present invention, and FIG. 2 shows a front part of the same. The steering shaft 11a is rotatably supported inside a tubular steering column 21 by a pair of front and rear rolling bearings 20a and 20b. The steering column 21 is supported by a pair of support brackets 22a and 22b provided at an intermediate portion on a vehicle body (not shown), the lower surface of an instrument panel, and the like. A steering wheel (not shown) is fixed to a portion of the steering shaft 11a at the rear end (the right end in FIG. 1) protruding from the rear end of the steering column 21.
The front end of the steering shaft 11a (FIGS.
2 (left end), the base end of one yoke 24a constituting the first universal joint 23 is fixed by welding to a portion protruding from the front end of the steering column 21. Via an intermediary shaft 25, it is connected to a rear end (right end in FIGS. 1 and 2) called an intermediate shaft. For this reason, the intermediate shaft 25
The base end of the other yoke 24b constituting the first joint 23 is fixed to the rear end by welding. A base end of a yoke 27 constituting a second universal joint 26 is fixedly connected to a front end (the left end in FIG. 2) of the intermediate shaft 25. 2
5 has a front end that can be freely connected to an input shaft of a steering gear (not shown).

Further, the steering shaft 11a
The outer shaft 12a corresponding to the outer member described in the claim and the inner shaft 13a corresponding to the inner member described in the claim can transmit torque between each other freely and in the axial direction (FIG. (1 to 3 left and right directions) so that the overall length is reduced when an impact load is applied in the axial direction. The outer shaft 12a is formed in a tubular shape as a whole, and the front end portion (left end portion in FIGS. 1 and 3) which is one end portion is subjected to drawing to form a small-diameter portion 44. A female serration 15a is formed on the peripheral surface. The inner shaft 13a also has a circular tubular shape as a whole, and is drawn from the rear end (the right end in FIGS. 1 and 3), which is one end, to an intermediate portion to thereby form the small diameter portion 4a.
The male serration 17a is formed on the outer peripheral surface of the small diameter portion 45 so as to engage with the female serration 15a.

The outer shaft 12a having the female serration 15a and the male serration 17a
And the inner shaft 13a having such a shape is fitted so that no relative displacement occurs unless a large axial load is applied between the shafts 12a and 13a. That is,
In order to prevent the engagement portion between the serrations 15a and 17a from rattling in a state where the serrations 15a and 17a are engaged with each other, an appropriate rattling preventing means is provided. As such rattling prevention means,
Conventionally known various structures can be adopted. For example,
As described in Japanese Utility Model Laid-Open Publication No. 6-8150, the tip of the outer shaft 12a existing at the axial front end (left end in FIGS. 1 and 3) of the fitting portion between the female serration 15a and the male serration 17a. After deforming the cross-sectional shape of the front end of the inner shaft 13a existing at the rear end in the axial direction (the right end in FIGS. 1 and 3) of the fitting portion and the fitting portion, the shafts 12a and 13a are connected to each other. Is fitted, the load required for shifting the fitting portion in the axial direction can be reduced, and the bending stiffness can be secured, so that favorable characteristics can be obtained as a steering shaft having an impact absorbing function.

In particular, in the steering shaft 11a which is the shock absorbing steering device of the present invention, the outer peripheral surface of the male serration 17a is usually separated from the front end edge of the outer shaft 12a, and
The shock absorbing member 28 is fitted to the position where the front end edge of the outer shaft 12a is displaced when the steering shaft 11a is contracted due to a collision accident. The shock absorbing member 28 has a cylindrical shape as a whole, and has a male serration 17 of the inner shaft 13a on its inner peripheral surface.
and a female spline 29 that engages with a. As shown in FIG. 5, the shock absorbing member 28 includes a pair of pressing pieces 30 that are displaced in a direction to crush the shock absorbing member 28,
By pressing inward in the diameter direction by 30, deformed portions 31, 31 having an elliptical cross-sectional shape are formed at two axial positions. Then, after forming such deformed portions 31, 31, the impact absorbing member 28 is pushed into the inner shaft 13 a, whereby the inner shaft 13 is formed.
a is fitted outside without rattling. Therefore, when the steering shaft 11a contracts due to a collision accident and the front edge of the outer shaft 12a abuts on the rear edge of the shock absorbing member 28, the shock absorbing member 28 is pressed by the outer shaft 12a. With this outer shaft 12a, it displaces with respect to the inner shaft 13a. That is, the steering shaft 11a is
It contracts while receiving resistance based on friction at the fitting portion between the shock absorbing member 28 and the inner shaft 13a.

On the other hand, the steering column 21 that supports the steering shaft 11a also includes an outer column 32 corresponding to an outer member described in claims and an inner column 33 corresponding to an inner member described in claims.
By freely combining the relative displacements in the axial direction, the overall length is reduced when a shocking load in the axial direction is applied. Outer column 3 of these
2 has a cylindrical shape as a whole, and forms deformation portions 34, 34 having an elliptical cross-sectional shape at two axial positions of a rear end (right end in FIGS. 1 and 3) as one end. I have. Then, the front end, which is one end of the inner column 33, is
Similarly, the inner column 33 is pressed against the rear end of the outer column 32 by being pushed into the rear end of the outer column 31 which is also cylindrical. Therefore, when a shocking load is applied to the steering column 21 in the axial direction due to a collision accident, the deformable portions 34, 34 slide on the outer peripheral surface of the inner column 33 and reduce the overall length of the steering column 21.

In particular, in the steering column 21, which is the shock absorbing type steering apparatus of the present invention, the outer peripheral surface of the inner column 33 is usually separated from the rear edge of the outer column 32, and A cylindrical shock absorbing member 28a is fitted to the position where the rear end edge of the outer column 32 is displaced when the stearin column 21 contracts due to a collision accident without looseness. The shock absorbing member 28 a is formed by forming a deformed portion 35 having an elliptical cross-sectional shape by pressing an intermediate portion in the axial direction inward in the diametrical direction. It fits outside without sticking. Therefore, when the steering column 21 contracts due to a collision accident and the rear end edge of the outer column 32 abuts on the front end edge of the shock absorbing member 28a, the shock absorbing member 28a is pressed by the outer column 32. While displacing with the outer column 32, the inner column 33 is displaced. That is,
The steering column 21 includes the shock absorbing member 28
It contracts while receiving the resistance based on the friction of the fitting part of the inner column 33 with the inner column 33.

Further, the intermediate shaft 25 connected to the steering shaft 11a via the first universal joint 23 also includes an outer shaft 36 corresponding to the outer member described in the claims and an inner shaft 25 described in the claims. By combining the corresponding inner shaft 37 and the inner shaft 37 so as to be relatively displaceable in the axial direction, the overall length is reduced when an impact force in the axial direction is applied. Of the outer shaft 36, the front end (left end in FIGS. 2 and 4), which is a half near one end, is slightly smaller in diameter than the rear half (right half in FIGS. 2 and 4). A female serration 38 is formed on the inner peripheral surface of the portion. The outer peripheral surface of the inner shaft 37 extends from the rear end (the right end in FIGS. 2 and 4), which is one end, to the middle (excluding the front end).
Male serration 39 engaging with female serration 38
Is formed. Further, deformed portions 40, 40 each having an elliptical cross-sectional shape are formed at two positions in the axial direction near the front end of the outer shaft 36. Then, by pushing the rear end of the inner shaft 37 into the front end of the outer shaft 36, the inner shaft 3
7 is connected to the outer shaft 36 without play.

In particular, in the intermediate shaft 25, which is the shock absorbing steering device of the present invention, the outer peripheral surface of the male serration 39 is normally separated from the front edge of the outer shaft 36 at the time of collision. When the intermediate shaft 25 contracts due to an accident, the outer shaft 36
A shock absorbing member 28b having a female serration 43 which engages with the male serration 39 on the inner peripheral surface thereof is fitted at the position where is displaced without rattling. The shock absorbing member 28b has a deformed portion 41 having an elliptical cross-sectional shape formed by pressing a middle portion in the axial direction inward in the diameter direction. It is fitted outside without sticking. Therefore, when the steering shaft 21 contracts due to a collision accident and the front edge of the outer shaft 36 abuts on the rear edge of the shock absorbing member 28b, the shock absorbing member 28b presses the outer shaft 36 against the outer shaft 36. The outer shaft 36 is displaced with respect to the inner shaft 37 together with the outer shaft 36. That is, the intermediate shaft 25
Contracts while receiving resistance based on friction at the fitting portion between the shock absorbing member 28b and the inner shaft 37.

In the case of the shock-absorbing steering device of the present invention having the above-described structure, each of the shock-absorbing members 28, 28a,
8b is displaced with respect to the inner member (inner shafts 13a, 37, inner column 33) together with the outer member while being pressed by the outer member (outer shafts 12a, 36, outer column 32). That is, the shock-absorbing steering device includes the shock-absorbing members 28, 28a, 28b.
The contraction load increases as shown by the solid line in FIG. For this reason, the impact absorbing members 28, 28a, 28b
The relationship between the amount of contraction and the contraction load can be adjusted as desired by adjusting the fitting strength and the fitting position. Further, when a plurality of shock absorbing members are externally fitted to the inner member while being spaced apart from each other in the axial direction, the contraction load can be increased stepwise as shown by the chain line in FIG. Furthermore, when a plurality of shock absorbing members are externally fitted to the inner member in this way, the fitting strength of each of the shock absorbing members is reduced to prevent a sudden increase in the shrinkage load, and to reduce the entire shrinkage range. It can be adjusted so that the shrinkage load does not become too small. Therefore, it is easy to adjust the contraction load of the steering device to be small in the initial stage and to gradually increase with an increase in the contraction amount, and an excessive impact is applied to the driver in the event of a collision, Alternatively, it is possible to more effectively prevent a large impact at the time of bottom striking. still,
In the case of this example, the example in which the shock absorbing members 28, 28a, 28b are assembled to all of the steering shaft 11a, the steering column 21, and the intermediate shaft 25 is shown.
It is not always necessary to assemble all the members 11a, 21, 25. Any of these members 11a, 21, 25 may be provided with a shock absorbing member according to the required shock absorbing characteristics.

Next, FIGS. 7 and 8 show a second example of the embodiment of the present invention. In the case of this example, the intermediate shaft 25a
The outer shaft 36 and the shock absorbing member 28c are attached to the inner shaft so that the phase of the deforming portions 40 and 40 of the outer shaft 36 and the phase of the deforming portion 41 of the shock absorbing member 28c are shifted by about 90 degrees in the circumferential direction. Each of the shafts 37 is externally fitted. That is, the minor diameter of the inner peripheral surface of the deformed portions 40 and 40 of the outer shaft 36 and the minor diameter of the inner peripheral surface of the deformed portion 41 of the shock absorbing member 28c are:
The positional relationship is approximately 90 degrees twist. Therefore, when the intermediate shaft 25a is contracted due to a collision accident, a contraction load is applied substantially uniformly in the circumferential direction of the intermediate shaft 25a. An elastomer such as rubber is provided between the rear edge of the shock absorbing member 28c (the right edge in FIG. 7) and the front edge (the left edge in FIG. 7) of the outer shaft 36 on the outer peripheral surface of the inner shaft 37. And the like. For this reason, a sudden increase in the contraction load generated when the edge of the shock absorbing member and the edge of the outer shaft come into contact can be mitigated. Other configurations and operations are the same as those of the above-described intermediate shaft 25 of the first example.

[0024]

Since the shock absorbing steering apparatus of the present invention is constructed and operates as described above, the relationship between the contraction amount and the contraction load can be adjusted as desired to effectively protect the driver.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a rear part of a first example of an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a former stage part.

FIG. 3 is an enlarged view of a portion A in FIG. 1;

FIG. 4 is an enlarged view of a portion B in FIG. 2;

5A is a cross-sectional view showing a step of pressing the shock absorbing member, and FIG. 5B is a view seen from the left side of FIG.

FIG. 6 is a diagram showing a relationship between a contraction amount and a contraction load in the structure of the first example.

FIG. 7 is a side view of a main part showing a second example of the embodiment of the present invention.

FIG. 8 is a view from the left side of FIG. 7;

FIG. 9 is a side view showing an example of a steering mechanism to which the present invention is applied.

FIG. 10 is a half vertical sectional side view showing an example of a conventional structure.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 First steering shaft 2 Steering wheel 3 Steering column 4 Rear bracket 5 Front bracket 6 Instrument panel 7 First universal joint 8 Second steering shaft 9 Second universal joint 10 Third steering shaft 11, 11a Steering shaft 12, 12a Outer shaft 13, 13a Inner shaft 14 Valley 15, 15a Female serration 16 Projection 17, 17a Male serration 19 Convex 20a, 20b Rolling bearing 21 Steering column 22a, 22b Support bracket 23 First free Joint 24a, 24b Yoke 25, 25a Intermediate shaft 26 Second universal joint 27 Yoke 28, 28a, 28b, 28c Shock absorbing member 29 Female spline 30 Pressing piece 31 Deformation part 32A Outer column 33 Inner column 34 Deformed part 35 Deformed part 36 Outer shaft 37 Inner shaft 38 Female serration 39 Male serration 40 Deformed part 41 Deformed part 42 Elastic material 43 Female serration 44 Small diameter part 45 Small diameter part

Claims (1)

[Claims] 1. An outer member formed in a cylindrical shape, and an inner member having one end inserted inside one end of the outer member, and a large axial load is applied between the outer member and the inner member. When the shock absorbing steering device is provided with a shock absorbing portion that is capable of contracting the axial dimension by the relative displacement of the outer member and the inner member in the axial direction when added, At least one externally fitted outer peripheral surface of the inner member at a position normally separated from one end edge of the outer member and at a position where one end edge of the outer member is displaced when the steering device contracts due to a collision accident. The shock absorbing member includes the inner member together with the outer member while being pressed by the outer member with the contraction of the shock absorbing steering device. Shock absorbing steering device characterized by being displaced with respect to