JP2607069Y2 - Shock absorbing steering shaft - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION The shock absorbing steering shaft according to the present invention is incorporated in a steering device of an automobile and used to transmit the movement of a steering wheel to a steering gear.

[0002]

2. Description of the Related Art In a steering apparatus for an automobile, a mechanism as shown in FIG. 5 is used to transmit the movement of a steering wheel to a steering gear. In FIG. 5, reference numeral 1 denotes a first steering shaft having a steering wheel 2 fixed to an upper end portion, and a steering column 3 fixed to a lower surface of an instrument panel 6 by upper and lower brackets 4, 5. Then, the first steering shaft 1 is provided inside the steering column 3,
It is rotatably supported. At the lower end of the first steering shaft 1, a portion protruding from the lower end opening of the steering column 3 is provided via a first universal joint 7.
The upper end of the second steering shaft 8 is connected. Further, the lower 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). With this configuration , the movement of the steering wheel 2 is controlled by the first steering shaft 1, the first universal joint 7, the second steering shaft 8, the second universal joint 9, To the steering gear via the steering shaft 10 to impart a steering angle to the wheels.

In the steering mechanism 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 is reduced by a shock. Conventionally, such a shock-absorbing steering shaft is disclosed in, for example,
What is described in -286468 is known. As shown in FIGS. 6 and 7, an impact-absorbing steering shaft as a first example of a conventional structure described in this publication includes an outer shaft 12 having a female serration 11 formed on an inner peripheral surface, and an outer Inner shaft 1 having male serration 13 engaged with female serration 11
4 and male serration 1 inside female serration 11
3 is inserted and combined. In addition, the synthetic resin 17 is inserted into the spaces 16, 16 between the concave portions 15, 15 formed on the outer peripheral surface of the inner shaft 14 and the inner peripheral surface of the outer shaft 12 through the through holes 19, 19 formed in the outer shaft 12. , 17 are injected and solidified to connect the outer shaft 12 and the inner shaft 14 to each other to form a shock absorbing steering shaft 18.

When a large force acts on the shock absorbing steering shaft 18 in the axial direction due to the collision, the synthetic resin 17, 17 forms a continuous portion between the spaces 16, 16 and the through holes 19, 19. Sheared. Further, the relative displacement between the outer shaft 12 and the inner shaft 14 is made freely, and the overall length of the shock absorbing steering shaft 18 is allowed to be reduced.

In Japanese Utility Model Publication No. 58-51096,
An impact absorbing steering shaft 18 having a structure as shown in FIGS. 8 and 9 is described. In the case of the conventional structure of the second example, in addition to the structure of the first example described above,
The small diameter part 25 is formed in the middle part of No.4. The steel balls 26, 26 disposed around the small diameter portion 25 are formed on the inner peripheral surface of the outer shaft 12 by female serrations 11.
The shock absorbing steering shaft 18 is fitted to the valleys 11b, 11b.

In the case of such a structure of the second example, when a large force acts in the axial direction of the shock absorbing steering shaft 18 due to a collision, the synthetic resin 17
Is sheared at a continuous portion between the hole and the through hole 19. Then, the relative displacement between the outer shaft 12 and the inner shaft 14 is made freely, and the overall length of the shock absorbing steering shaft 18 is allowed to be reduced. When the overall length of the shock absorbing steering shaft 18 is reduced, the relative displacement between the outer shaft 12 and the inner shaft 14 is reduced while the steel balls 26, 26 plastically deform the inner surface of the female serration 11. Allow.

Further, Japanese Utility Model Laid-Open No. 63-147363 discloses an impact absorbing steering shaft 18 having a structure as shown in FIGS. In the case of the third example of this conventional structure, the end of the outer shaft 12 is formed in a substantially triangular cylindrical shape with rounded corners, and the end of the inner shaft 14 is formed in a hexagonal cylindrical shape. Then, both ends are slidably fitted to each other, and steel balls 26, 26 are inserted into gap spaces 27, 27 between the inner peripheral surface of the outer shaft 12 and the outer peripheral surface of the inner shaft 14. Press-fit through the through hole 28 formed in
The shock absorbing steering shaft 18 is used.

In the case of such a structure of the third example, when a large force acts in the axial direction of the shock-absorbing steering shaft 18 due to a collision, the steel balls 26, 26 come into contact with the inner peripheral surface of the outer shaft 12. Relative displacement between the outer shaft 12 and the inner shaft 14 is allowed while plastically deforming the outer peripheral surface of the inner shaft 14.

[0009]

In the case of the conventional shock absorbing steering shaft as described above, the collapse load cannot be gradually increased as the amount of collapse increases. For this reason, if the collapse load is small, the shock absorbing steering shaft contracts and cuts off (full collapse),
A large resistance is generated at the time of contraction, that is, the so-called bottom striking. On the other hand, when the collapse load is large, a large resistance is generated at the moment when the shock absorbing steering device starts to contract,
It is difficult to enhance the protection of the driver.

In order to effectively absorb the impact energy in the event of a collision and to effectively protect the driver, it is preferable that the collapse load increases with an increase in the amount of collapse. In the case of the conventional shock-absorbing steering shafts as shown in FIGS. 6 to 11, none of them can cope with such a demand, and it is difficult to design a steering apparatus for an automobile which can sufficiently enhance protection of the driver. The shock absorbing steering shaft of the present invention has been invented in view of such circumstances.

[0011]

The shock-absorbing steering shaft according to the present invention is an inner shaft having a male serration formed on the outer peripheral surface, for example, like the conventional shock-absorbing steering shaft shown in FIGS. And an outer shaft having a female serration formed on an inner peripheral surface thereof. By engaging the male serration and the female serration, the inner shaft and the outer shaft can be freely combined with each other to transmit a rotational force. An impact absorbing portion is provided between the shaft and the outer shaft so that the axial dimension can be contracted only when a large axial load is applied.

In particular, in the shock absorbing steering shaft of the present invention, the shock absorbing portion is a part of the valley of the male serration, and does not normally engage with the female serration, which may cause a collision accident. When the steering shaft is contracted, it includes a projection fixed to a portion engaging with the female serration. The projection is deformed by engagement with the female serration ridge as the shock absorbing steering shaft contracts.

[0013]

SUMMARY OF] constructed as described above, when the shock absorbing steering shaft of the present invention, with an increase in the amount of collapse,
The collapse load can be gradually increased. That is, when the shock absorbing steering shaft contracts due to the occurrence of a collision accident, the projection engages with the peak of the female serration during the contraction. Then, after the protrusion and the peak portion of the female serration are engaged, the collapse load increases. As described above, the collapse load increases as the amount of collapse increases, thereby facilitating design for enhancing protection of the driver in the event of a collision. Moreover, the shock absorbing type of the present invention
In the case of a steering shaft, attach the protrusion to the male
Because this is formed in a part of the valley of the
Good machining can be performed easily. Also, at the time of secondary collision
The operation of collapsing the female serration peaks by
On the side of the serration valley and the female serration peak
Since this is performed in an enclosed space that is more enclosed,
Collapse in a stable state (always collapse in the same state).
For this reason, the engagement between the protrusion and the crest of the female serration is performed.
The collapse load based on the
I can make it.

[0014]

1 to 4 show an embodiment of the present invention.
The shock absorbing steering shaft 29 of the present invention is the same as the conventional shock absorbing steering shaft 18 described above (FIG. 6).
Similarly to 11), by combining the outer shaft 12 and the inner shaft 14 so as to be freely displaceable in the axial direction, the overall length is reduced when an impact force in the axial direction is applied.

The outer shaft 12 has a cylindrical shape as a whole, and a female serration 11 is formed on the inner peripheral surface at one end. Further, the inner shaft 14 has a cylindrical shape as a whole, and has a male serration 13 that engages with the female serration 11 on the inner peripheral surface of the outer shaft 12 on one end outer peripheral surface.

The female serrations 11 and the male serrations 13 are formed, as in the case of general serrations, by setting the tops of the peaks 11a, 13a to the respective valleys 13a.
When these female serrations 11 and male serrations 13 are engaged without entering the bottoms of b and 11b,
Gaps 20, 21 are formed between the top and bottom.

Further, in the case of the shock absorbing steering shaft 29 of the present embodiment, the height dimension of the gap 21 is provided at two positions axially separated from each other at the bottom of the valley 13b of the male serration 13. A protrusion 22 having a height H (h <H) slightly larger than (radial dimension) h;
22 are formed. Each of these bosses 22 and 22, in order to an impact absorbing type steering shaft 29 by coupling the the outer shaft 12 and inner shaft 14, when inserting the male serration 13 on the female serration 11, the female serration 11 The outer shaft 12 and the inner shaft 14 are prevented from being displaced from each other in the axial direction, and these two shafts 12 and 14 are connected to each other. In the case of this embodiment, the rear end surfaces of the protruding portions 22, 22 (the rear end surface of the inner shaft 14 and the right end surface in FIG. 1) are inclined to reduce the total length of the shock absorbing steering shaft 29 during collapse. The plastic deformation of the crest 11a of the female serration 11 by the projections 22, 22 can be performed smoothly.

At the base end (the left end in FIG. 1) of the male serration 13 on the outer peripheral surface of the inner shaft 14, a projection 23 having a height larger than the projections 22, 22 is formed. I have. The projection 23 is normally exposed outside the outer shaft 12 (before the collision), but when the overall length of the shock absorbing steering shaft 29 is reduced due to the collision, the inner peripheral surface of the outer shaft 12 is reduced. Of the female serration 11 of the shock absorbing type steering shaft 29, thereby reducing the overall length of the shock absorbing steering shaft 29. In addition, as described above, the protrusion 22 is provided on a part of the valley 13b.
Since the male serration 13 provided with 23 is formed by rolling, the manufacturing cost of the inner shaft 14 does not increase. In addition, the dimensions and shape accuracy of each of the protrusions 22 and 23 are described.
Is sufficiently high, similar to the accuracy of male serration 13 above.
The protrusions 22 and 23 and the ridge 11a
The magnitude of the above resistance based on engagement with
Can be determined.

As described above, since the connection between the outer shaft 12 and the inner shaft 14 is performed by the protruding portions 22 formed integrally with the inner shaft 14 made of metal, the heat resistance of the connection portion is sufficient, and Insufficiency of the supporting force of the joint portion is prevented depending on the conditions. Also, the protrusion 22,
The outer shaft 12 and the inner shaft 14 are provided at two positions separated from each other in the axial direction.
The bending stiffness of the joint portion is sufficiently ensured.

When a strong force is applied in the axial direction at the time of collision, each of the projections 22 plastically deforms the top of the peak 11a of the female serration 11 and Relative displacement with respect to the inner shaft 14 is allowed, and the overall length of the shock absorbing steering shaft 29 is reduced. Furthermore, at the time of the collapse accompanying such a collision,
Immediately after each of the protrusions 22 starts to be displaced, the another protrusion 23 and the crest 11a engage with each other to increase the collapse load, thereby absorbing the impact force accompanying a collision accident. Can be done.

In the case of the shock-absorbing steering shaft 29 of the present embodiment, each of the projections 22, 22 is
Since only a small area is in contact with the top of a, the force required to cause the plastic deformation is relatively small. Therefore, the collapse load required to reduce the overall length of the shock absorbing steering shaft 29 is stable without increasing, and effectively prevents a large impact force from being applied to the driver's body colliding with the steering wheel in the event of a collision. I can do it. In addition, since the collapse load can be increased midway, the design for enhancing protection of the driver is facilitated. That is, when the collapse load is increased, the maximum value (peak load) of the collapse load required to start the collapse tends to be large. Since the engagement is performed after the start of the collapse, the peak load does not increase. Also, as described above, only the projections 22 and 22 are used.
And the size and shape accuracy of the protrusion 23 are sufficiently ensured.
it can. Further, at the time of a secondary collision,
The operation of crushing the peak 11a of the serration 11 is performed by the male
Side of the valley 13b of the housing 13 and the female serration
In a closed space surrounded by the mountain 11a of the housing 11
Therefore, the peak 11a is crushed in a stable state.
In other words, the mountain 11a is always in the same state.
Collapse. Therefore, the collapse load is stable as designed
To protect the driver in the event of a secondary collision.
Effectively.

The collapse load is applied to each of the projections 2
The height can be arbitrarily adjusted by changing the length L and the number (the number in the axial direction or the number in the circumferential direction) in addition to the height dimension H of 2, 22. In order to stabilize the collapse load, if necessary, before the shock absorbing steering shaft 29 is installed inside the steering column 3 (FIG. 5), the shock absorbing steering shaft 29 is expanded and contracted once. Each of the projections 22, 22 is connected to the peak 11a.
May be moved on the top of the.

When the collapse load is adjusted in the present embodiment, the height H, length L, and the number of the projections 22, 22 are changed, and the projections 22, 22 are changed. It can also be adjusted by changing the angle of inclination of the front end face of the vehicle. or,
The timing at which the collapse load increases after the start of the collapse can be adjusted by changing the distance between the end of the female serration 11 and the front end surface of the projection 23.

[0024]

Shock absorbing type steering shaft of the present invention, according to the invention], in order to act configured as mentioned above, it is possible to <br/> ing to increase with the collapse load to collapse of increase. In addition, this collapse load is stable as designed
Since it can be generated in a state where the vehicle is in a crashed state, it is possible to effectively protect the driver's body in the event of a collision accident.

[Brief description of the drawings]

FIG. 1 is a half vertical sectional side view showing an embodiment of the present invention.

FIG. 2 is a partially enlarged perspective view of a male serration.

FIG. 3 is a sectional view taken along line AA of FIG. 1;

FIG. 4 is a sectional view taken along the line BB in FIG.

FIG. 5 is a side view showing an example of a steering mechanism incorporating the shock absorbing steering shaft according to the present invention.

FIG. 6 is a longitudinal sectional side view showing a first example of a conventional structure.

FIG. 7 is a sectional view taken along line CC of FIG. 6;

FIG. 8 is a vertical sectional side view showing a second example of the conventional structure.

FIG. 9 is a sectional view taken along the line DD in FIG. 8;

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

FIG. 11 is a sectional view taken along line EE of FIG. 14;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 First steering shaft 2 Steering wheel 3 Steering column 4 Upper bracket 5 Lower bracket 6 Instrument panel 7 First universal joint 8 Second steering shaft 9 Second universal joint 10 Third steering shaft 11 Female serration 11a Peak 11b Valley 12 Outer Shaft 13 Male Serration 13a Peak 13b Valley 14 Inner Shaft 15 Concave 16 Space 17 Synthetic Resin 18 Shock Absorbing Steering Shaft 19 Through Hole 20 Gap 21 Gap 22 Projection 23 Projection 24 Projection 25 Small diameter part 26 Steel ball 27 Clearance space 28 Through hole 29 Shock absorbing steering shaft

Claims (1)

(57) [Scope of request for utility model registration] 1. An inner shaft having a male serration formed on an outer peripheral surface thereof and an outer shaft having a female serration formed on an inner peripheral surface thereof. The inner shaft and the outer shaft are formed by engaging the male serration and the female serration. A shock absorber that combines a shaft and a shaft so that torque can be freely transmitted, and a shock absorber between the inner shaft and the outer shaft that allows the axial dimension to contract only when a large axial load is applied. In the type steering shaft, this shock absorbing part is
A part of the valley of the male serration, which does not normally engage with the female serration, and includes a protrusion fixed to a portion which engages with the female serration when the steering shaft contracts due to a collision accident. Wherein the projection is deformed by engagement with the female serration ridge in accordance with the contraction of the shock-absorbing steering shaft. shaft.