JPH0535542U - Shock absorption type steering shaft - Google Patents

Abstract

(57) [Abstract] [Purpose] Outer shaft 12 and inner shaft 14
The heat resistance of the joint with and is ensured and the collapse load is reduced. [Structure] A female serration groove 11 on an inner peripheral surface of an outer shaft 12 and a male serration groove 13 on an outer peripheral surface of an inner shaft 14 are engaged with each other. A recess 25 is provided on the outer peripheral surface of the inner shaft 14 in alignment with the valley 24 of the male serration groove 13, and a steel ball 26 is inserted into the recess 25. Then, a part of the steel ball 26 is made to bite into the top portion 27 of the mountain portion of the female serration groove 11.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

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

[0002]

[Prior Art]

 In a vehicle steering system, a mechanism as shown in FIG. 4 is used to transmit the movement of a steering wheel to a steering gear. In FIG. 4, reference numeral 1 denotes a first steering shaft having a steering wheel 2 fixed to an upper end portion thereof, and 3 denotes a steering wheel fixed to a lower surface of an instrument panel 6 by upper and lower brackets 4 and 5. In the column, the first steering shaft 1 is rotatably inserted inside the steering column 3.

An upper end portion of a second steering shaft 8 is connected to a portion of the lower end portion of the first steering shaft 1 protruding from a lower end opening of the steering column 3 via a first universal joint 7. is doing. Further, the lower end portion of the second steering shaft 8 is connected via a second universal joint 9 to a third steering shaft 10 leading to a steering gear (not shown).

Since the steering wheel 2 is formed as described above, the movement of the steering wheel 2 is such that the first steering shaft 1 having the steering column 3 inserted therein, the first universal joint 7, the second steering ring 8, and the second steering shaft 8. The steering angle is transmitted to the steering gear via the universal joint 9 and the third steering shaft 10 to give a steering angle to the wheels.

By the way, in the steering mechanism configured as described above, in order to protect the driver in the event of a collision, the steering column 3 and each of the steering shafts 1 and 8 are shock-absorbed so that the entire length is shortened due to the impact. Generally, a shock absorbing steering shaft is disclosed, for example, as disclosed in Japanese Patent Application Laid-Open No. 2-284686.

The shock absorbing steering shaft, which is the first example of the conventional structure described in this publication, has an outer shaft 12 having a female serration groove 11 formed on the inner peripheral surface thereof, as shown in FIGS. , And an inner shaft 14 having a male serration groove 13 which engages with the female serration groove 11 on the outer peripheral surface thereof, is combined with the male serration groove 13 inserted inside the female serration groove 11. ..

Further, in the spaces 16, 16 between the recesses 15, 15 formed on the outer peripheral surface of the inner shaft 14 and the inner peripheral surface of the outer shaft 12, through holes 19, 19 formed in the outer shaft 12 are formed. By injecting and solidifying the synthetic resin 17, 17 through the above, the outer shaft 12 and the inner shaft 14 are connected to each other to form a shock absorbing steering ring shaft 18.

When a large force acts in the axial direction of the shock absorbing steering shaft 18 due to a collision accident, the synthetic resins 17, 17 cause the spaces 16, 16 and the through holes 19, 19 to come into contact with each other. It is sheared at the continuous portion, and the relative displacement between the outer shaft 12 and the inner shaft 14 is freely allowed to allow the entire length of the shock absorbing steering shaft 18 to be shortened.

Further, Japanese Utility Model Publication No. 58-51096 discloses a shock absorbing steering shaft having a structure as shown in FIGS. In the case of the conventional structure of the second example, in addition to the structure of the first example, the small diameter portion 20 is formed in the intermediate portion of the inner shaft 14, and the steel balls 21 and 21 arranged around the small diameter portion 20 are It is fitted in the troughs 22, 22 of the female serration groove 11 formed on the inner peripheral surface of the outer shaft 12.

In the case of the structure of the second example, when a large force acts in the axial direction of the shock absorbing steering shaft 18 with a collision, the synthetic resin 17 causes the space 16 and the through hole 19 to continue. The shock absorbing steering shaft 18 is sheared at a portion, and the relative displacement between the outer shaft 12 and the inner shaft 14 is freely allowed to allow the entire length of the shock absorbing steering shaft 18 to be shortened. When the overall length of the shock absorbing steering shaft 18 is shortened, the steel balls 21, 21 plastically deform the inner surface of the female serration groove 11 while the outer shaft 12 and the inner shaft 14 are relatively moved. Allow displacement.

[0011]

[Problems to be solved by the device]

 However, in the case of these conventionally known shock absorbing steering shafts, there are the following problems to be solved.

That is, in the case of the structure of the first example, since the outer shaft 12 and the inner shaft 14 are coupled and supported only by the synthetic resins 17 and 17, the heat resistance is insufficient and the engine tends to become high in temperature. Depending on the usage conditions, such as when installing in a room, it may not be possible to obtain sufficient support.

Further, in the case of the structure of the second example, the steel balls 21, 21 are in contact with the inner surface of the valley portion 22 of the female serration groove 11 at two points respectively. Since the structure allows the relative displacement of the outer shaft 12 and the inner shaft 14 while plastically deforming the position, the force (so-called collapse load) required to reduce the overall length of the shock absorbing steering shaft 18 is large. It tends to be.

When the collapse load becomes large, in the case of a collision accident, the backward movement of the steering gear due to the collision is not absorbed in the middle of the collision, or the driver's body collides with the steering wheel and is added to the steering wheel. This is not preferable because the forward impact is not absorbed and a large impact is applied to the driver's body that collides with the steering wheel, which is likely to cause serious injury to the driver.

The shock absorbing steering shaft of the present invention eliminates all of the above-mentioned inconveniences.

[0016]

[Means for solving the problem]

 The shock absorbing steering shaft of the present invention comprises an outer shaft having a female serration groove formed on the inner peripheral surface, an inner shaft having a male serration groove engaging with the female serration groove formed on the outer peripheral surface, and the inner shaft. On the outer peripheral surface of the male serration groove, a concave portion formed in a portion corresponding to the valley of the male serration groove and a hard member inserted in the concave portion are formed to engage the female serration groove with the male serration groove. At the same time, a part of the hard member is made to bite into the top of the mountain portion of the female serration groove.

[0017]

[Action]

 In the case of the shock absorbing steering shaft of the present invention configured as described above, a part of the hard member inserted in the recess on the outer peripheral surface of the inner shaft is the top of the mountain portion of the female serration groove on the inner peripheral surface of the outer shaft. The outer shaft and the inner shaft are coupled to each other by biting into.

Further, when a strong force is applied in the axial direction at the time of collision, the hard member plastically deforms the top of the mountain portion of the female serration groove, and the relative position between the outer shaft and the inner shaft. Allows displacement and shortens the overall length of the shock absorbing steering shaft. Since the hard member is in contact with the female serration groove at the top of the mountain portion of the female serration groove, the collapse load required to reduce the entire length of the shock absorbing steering shaft is not increased. Absent.

[0019]

【Example】

 1 and 2 show a first embodiment of the present invention. The shock absorption type steering shaft 23 of the present invention, like the conventional shock absorption type steering shaft 18 (FIGS. 5 to 8), allows the outer shaft 12 and the inner shaft 14 to be relatively displaceable in the axial direction. By combining them, the overall length is shortened when an axial impact force is applied.

The outer shaft 12 has a circular tubular shape as a whole, and a female serration groove 11 is formed on the inner peripheral surface of one end thereof. The inner shaft 14 has a circular rod shape as a whole, and has a male serration groove 13 which engages with the female serration groove 11 on the inner peripheral surface of the outer shaft 12 at the outer peripheral surface of one end thereof.

A recess 25 is formed in the outer peripheral surface of one end of the inner shaft 14 at a portion corresponding to the valley 24 of the male serration groove 13, and a steel ball 26, which is a hard member, is inserted into the recess 25. ing. Then, by engaging the female serration groove 11 and the male serration groove 13, the outer shaft 12 and the inner shaft 14 are combined, and at the same time, a part of the steel ball 26 is removed from the mountain portion of the female serration groove 11. It is digging into the top 27.

In the case of the shock absorbing steering shaft 23 of the present invention configured as described above, a part of the steel ball 26 inserted into the recess 25 formed on the outer peripheral surface of the one end portion of the inner shaft 14 has a part of the outer shaft 12 The outer shaft 12 and the inner shaft 14 are coupled to each other by biting into the top portion 27 of the mountain portion of the female serration groove 11 formed on the inner peripheral surface of the.

As described above, since the outer shaft 12 and the inner shaft 14 are connected to each other by the steel balls 26, the heat resistance of the joint becomes sufficient, and the supporting force of the joint does not become insufficient depending on the usage conditions.

When a strong force is applied in the axial direction at the time of collision, the steel ball 26 plastically deforms the top portion 27 of the mountain portion of the female serration groove 11, while the outer shaft 12 and the inner shaft 26 are being deformed. The relative displacement with respect to 14 is allowed, and the overall length of the shock absorbing steering shaft 23 is shortened.

In the case of the shock absorbing steering shaft 23 of the present invention, since the steel ball 26 is in contact with the female serration groove 11 at the top 27 of the mountain portion of the female serration groove 11, The force required to cause the deformation is comparatively small (compared to the second example of the related art). Therefore, the collapse load required to reduce the overall length of the shock absorbing steering shaft 23 does not increase, and it is possible to effectively prevent a large impact force from being applied to the driver's body that collides with the steering wheel in the event of a collision accident. ..

In the illustrated embodiment, the recess 25 and the steel ball 26 are provided only at one position in the axial direction, but if the serration engagement part is long, a plurality of these are provided. Is also good. Also, in order to stabilize the so-called collapse load, which is required to reduce the overall length of the shock absorbing steering shaft 23 at the time of a collision, before the shock absorbing steering shaft 23 is installed inside the steering column 3, the shock absorbing steering shaft 23 is absorbed. The steel steering shaft 23 may be expanded and contracted once, and the steel ball 26 may be moved on the top portion 27.

Further, as in the second embodiment shown in FIG. 3, the recesses 25, 25 and the steel balls 26, 26 can be provided at a plurality of positions in the circumferential direction. When the recesses 25, 25 and the steel balls 26, 26 are thus provided at a plurality of positions in the circumferential direction, the supporting force acting between the inner peripheral surface of the outer shaft 12 and the outer peripheral surface of the inner shaft 14 is It becomes almost uniform in the circumferential direction, and the displacement between the shafts 12 and 14 at the time of collision is performed more smoothly.

[0028]

[Effect of the device]

 Since the shock absorbing steering shaft of the present invention is constructed and operates as described above, it ensures sufficient heat resistance and the collapse load is sufficiently low to ensure the safety of the driver in the event of a collision accident. You can effectively secure.

[Brief description of drawings]

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

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a sectional view similar to FIG. 2, showing a second embodiment of the present invention.

FIG. 4 is a side view showing an example of a steering mechanism that incorporates a shock absorbing steering shaft that is the subject of the present invention.

FIG. 5 is a vertical sectional side view showing a first example of a conventional structure.

6 is a sectional view taken along line BB of FIG.

FIG. 7 is a half-section vertical side view showing a second example of the conventional structure.

8 is a sectional view taken along line CC of FIG.

[Explanation of sign]

 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 Groove 12 Outer shaft 13 Male serration groove 14 Inner shaft 15 Recess 16 Space 17 Synthetic resin 18 Impact absorbing steering shaft 19 Through hole 20 Small diameter portion 21 Steel ball 22 Valley portion 23 Impact absorbing steering shaft 24 Valley portion 25 Recess 26 Steel ball 27 top

Claims (1)

[Scope of utility model registration request] 1. An outer shaft having a female serration groove formed on an inner peripheral surface thereof, an inner shaft having a male serration groove formed on an outer peripheral surface thereof for engaging with the female serration groove, and an outer peripheral surface of the inner shaft comprising the male shaft. A recess formed in a portion corresponding to the trough of the serration groove, and a hard member inserted into this recess, while engaging the female serration groove and the male serration groove, a part of the hard member, A shock-absorbing steering shaft that bites into the top of the mountain portion of the female serration groove.