JPH0532228U - 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. The cage 27 is inserted into the radial gap 26 between the inner peripheral surface of the outer shaft 12 and the outer peripheral surface of the inner shaft 14. The balls 28, 28 held on both ends of the cage 27 are attached to the inner peripheral surface of the outer shaft 12 and the outer peripheral flat surface 25 of the inner shaft 14.
Make a strong contact with.

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. 9 is used to transmit the movement of a steering wheel to a steering gear. In FIG. 9, 1 is a first steering shaft having a steering wheel 2 fixed to its upper end, 3 is a steering wheel fixed to the 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. It is transmitted to the steering gear through the universal joint 9 and the third steering shaft 10 and imparts 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.

A shock absorbing type steering shaft, which is a first example of a conventional structure described in this publication, has an outer shaft 12 having a female serration groove 11 formed on an 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 are combined into a state in which the male serration groove 13 is inserted inside the female serration groove 11. ing.

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 on the shock absorbing steering shaft 18 in the axial direction due to the collision, the synthetic resins 17, 17 cause the spaces 16, 16 and the through holes 19, 19 to continue. The outer shaft 12 and the inner shaft 14 are sheared at a portion, and the relative displacement between the outer shaft 12 and the inner shaft 14 can be freely performed 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, a 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 attached to the outer portion. The shock absorbing steering shaft 18 is fitted into the troughs 22, 22 of the female serration groove 11 formed on the inner peripheral surface of the 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.

Further, Japanese Utility Model Laid-Open No. 63-147363 discloses a shock absorbing steering shaft having a structure as shown in FIGS. In the case of the conventional structure of the third example, the end portion of the outer shaft 12 is formed into a substantially triangular tube shape with rounded corners, and the end portion of the inner shaft 14 is formed into a hexagonal tube shape, and both end portions are joined together. And the steel balls 21, 21 are formed in the outer shaft 12 in the gap spaces 23, 23 between the inner peripheral surface of the outer shaft 12 and the outer peripheral surface of the inner shaft 14. The shock absorbing steering shaft 18 is press-fitted through the through hole 24.

In the case of the 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 21 and 21 come into contact with the outer peripheral surface of the outer shaft 12. While allowing the inner peripheral surface of the inner shaft 14 to be plastically deformed, the relative displacement between the outer shaft 12 and the inner shaft 14 is allowed.

[0013]

[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.

First, 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 temperature tends to be high. Depending on the operating conditions, such as installing in the engine room, it may not be possible to obtain sufficient torsional durability.

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, and at the time of collision, the two balls Since the structure allows the relative displacement between the outer shaft 12 and the inner shaft 14 while plastically deforming the position, the steel balls 21 and 21 do not rotate but mainly slide and displace. The force (so-called collapse load) required to reduce the overall length of the absorption steering shaft 18 tends to increase.

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, 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.

Further, in the case of the structure of the third example, the work of assembling the steel balls 21, 21 from the through hole 24 of the outer shaft 12 requires time and labor, and it is difficult to regulate the axial position, and stable performance is achieved. Can't get That is, as shown in FIG. 14, if the steel balls 21 are provided only at one axial position, the bending rigidity of the shock absorbing steering shaft 18 constituted by the outer shaft 12 and the inner shaft 14 is sufficiently secured. Can not . In order to secure this bending rigidity, it is conceivable to provide the steel balls 21, 21 at a plurality of axial positions, but in the case of the structure of the third example, it is difficult to regulate the axial positions of the steel balls 21, 21. Therefore, the bending rigidity cannot be stabilized.

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

[0019]

[Means for Solving the Problems] A shock absorbing steering shaft of the present invention comprises a tubular outer shaft, an inner shaft combined with the outer shaft, which is freely displaceable in the axial direction, and an inner shaft. A radial gap provided between the outer peripheral surface of the shaft and the inner peripheral surface of the outer shaft, a cage inserted in the radial gap so as to be displaceable in the axial direction, and separated in the axial direction. And a rolling element rotatably held by the retainer at at least two positions, and the rolling element is strongly brought into contact with the inner peripheral surface of the outer shaft and the outer peripheral surface of the inner shaft. Therefore, the outer shaft and the inner shaft are connected to each other.

[0020]

[Action]

 In the case of the shock absorbing steering shaft of the present invention configured as described above, the outer surface of the rolling element bites into the inner peripheral surface of the outer shaft and the outer peripheral surface of the inner shaft while rotating to form the outer shaft. Connect the inner shaft with each other.

Further, when a strong force is applied in the axial direction at the time of collision, the rolling element plastically deforms the inner peripheral surface of the outer shaft and the outer peripheral surface of the inner shaft, and the outer shaft and the inner shaft are deformed. Allows relative displacement with the shaft to reduce the overall length of the shock absorbing steering shaft.

Further, in the case of the shock absorbing steering shaft of the present invention, since the rolling elements are held by the retainer at at least two axially separated positions, the outer shaft and the inner shaft are coupled. The bending rigidity of the part is sufficiently secured.

[0023]

【Example】

 1 to 4 show a first embodiment of the present invention. The shock absorption type steering shaft 30 of the present invention, like the conventional shock absorption type steering shaft 18 (FIGS. 10 to 15) described above, 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 impact force is applied in the axial direction.

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

A flat surface 25 is formed on a portion of the outer peripheral surface of one end of the inner shaft 14 where the male serration groove 13 is not formed, and the flat surface 25 and the inner peripheral surface of the outer shaft 12 are formed. A radial gap 26 is provided between A cage 27 and metal balls 28, 28, which are rolling elements, are mounted in the radial gap 26.

The cage 27 made of synthetic resin is inserted in the radial gap 26 so as to be displaceable in the axial direction (left and right directions in FIGS. 1, 3 and 4), and the ball is provided at both ends in the axial direction. Pockets 29, 29 for holding the rolls 28, 28 rotatably are formed. Then, the balls 28, 28 rotatably held in the respective pockets 29, 29 are press-fitted into the radial gap 26, so that the surfaces of the balls 28, 28 are kept inside the outer shaft 12. The peripheral surface and the flat surface 25 formed on the outer peripheral surface of the inner shaft 14 are strongly brought into contact with each other. As a result, a part of the outer surface of each ball 28, 28 digs into the inner peripheral surface and the flat surface 25 to connect the outer shaft 12 and the inner shaft 14.

That is, when the shock absorbing steering shaft 30 of the present invention is assembled, as shown in FIG. 3, the inner shaft 14 is held at the end of the flat surface 25 and at both ends of the retainer 27 in the axial direction. The ball 28, 28 is placed, and the ball 28, 28 together with the retainer 27 is inserted into the radial gap 26 in the outer shaft 12. Since the outer diameters of the balls 28, 28 are slightly larger than the width dimension of the radial clearance 26 in the radial direction, the inner shaft 14 can be moved from the state shown in FIG. 3 to the state shown in FIG. As the balls are inserted into the outer shaft 12, the balls 28, 28 held by the retainer 27 are press-fitted into the radial gaps 26, and after press-fitting, the outer surfaces of the balls 28, 28 are pressed. Part of which penetrates into the inner peripheral surface and the flat surface 25 to connect the outer shaft 12 and the inner shaft 14.

As described above, since the outer shaft 12 and the inner shaft 14 are connected to each other by the metal balls 28, 28, the heat resistance of the connecting portion is sufficient, and the supporting force of the connecting portion depends on the use conditions. There will be no shortage. Further, the balls 28, 28 are provided in the radial gap 26 at two positions separated from each other in the axial direction, and the installation positions of the balls 28, 28 are restricted by the cage 27. The bending rigidity of the joint between the outer shaft 12 and the inner shaft 14 is sufficiently ensured.

Further, when a strong force is applied in the axial direction at the time of a collision, as shown in FIG. 4, the balls 28, 28 are rotated and the inner peripheral surface of the outer shaft 12 and the inner shaft are rotated. The flat surface 25 of 14 is plastically deformed to allow relative displacement between the outer shaft 12 and the inner shaft 14, and the overall length of the shock absorbing steering shaft 30 is shortened.

In the case of the shock absorbing steering shaft 30 of the present invention, the balls 28, 28 are in contact with the inner peripheral surface and the flat surface 25 only in a small area, and the balls 28, 28 rotate. Since it moves while moving, the force required to generate the plastic deformation is relatively 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 30 does not increase and stabilizes, and in the event of a collision, a large impact force is applied to the body of the driver who collides with the steering wheel. It can be effectively prevented.

Further, in the illustrated embodiment, since the inner diameter of the outer shaft 12 is increased from the middle, the amount of force required to reduce the overall length of the shock absorbing steering shaft 30 is decreased from the middle. The amount of stroke (the amount of contraction of the shock absorbing steering shaft 30) required until the force becomes small can be set arbitrarily according to the shape of the outer shaft 12.

If necessary, in order to stabilize the so-called collapse load required to reduce the overall length of the shock absorbing steering shaft 30 at the time of a collision, the shock absorbing steering shaft 30 may be installed on the steering column 3 ( Before being incorporated in the inside of FIG. 9), the shock absorbing steering shaft 30 may be once expanded and contracted to move the balls 28, 28 on the inner peripheral surface and the flat surface 25.

Next, FIG. 5 shows a second embodiment of the present invention. While the balls 28, 28 (FIGS. 1 to 4) were used as the rolling elements held at the both ends in the axial direction of the cage 27 in the above-mentioned first embodiment, in the case of this embodiment, A roller 31 is used as a rolling element, and the outer peripheral surface of the roller 31 is brought into contact with the inner peripheral surface of the outer shaft 12 and the flat surface 25 of the inner shaft 14. Other configurations and operations are similar to those of the first embodiment described above.

Next, FIG. 6 shows a third embodiment of the present invention. In each of the above-mentioned first to second embodiments, the outer shaft 12 and the inner shaft 14 are freely combined only in the axial displacement, so that the female serration groove 11 and the male serration groove 13 are engaged with each other. In contrast to this (FIGS. 2 and 5), in the case of this embodiment, the outer shaft 12 and the inner shaft 14 are freely combined only by axial displacement by the needles 32 and 32.

That is, the inner peripheral surface of the outer shaft 12 and the outer peripheral surface of the inner shaft 14 are aligned with each other at the portions where the grooves 33 and 34 each having an arcuate cross section are formed in the axial direction. The needles 32, 32 are bridged over the biconcave grooves 33, 34. Further, the rigidity of this joint is improved by providing two balls 28, 28 at both ends in the axial direction, each in the direction perpendicular to the axial direction. Other configurations and operations are similar to those of the first embodiment described above.

Next, FIG. 7 shows a fourth embodiment of the present invention. In the case of the present embodiment, the concavo-convex portions 35 and 36 that are continuous in the axial direction are formed by forming the portions of the outer shaft 12 and the inner shaft 14 that are aligned with each other by drawing. By engaging with each other, the outer shaft 12 and the inner shaft 14 are freely combined only in the axial displacement. Other configurations and operations are similar to those of the above-described first embodiment.

Next, FIG. 8 shows a fifth embodiment of the present invention. In the case of this embodiment, by holding two balls 28, 28 in total in the axial direction at both ends of the retainer 27, the bending rigidity of the connecting portion between the outer shaft 12 and the inner shaft 14 can be improved. It is improving further. Other configurations and operations are similar to those of the first embodiment described above.

[0038]

[Effect of the device]

 Since the shock absorbing steering shaft of the present invention is constructed and operates as described above, it is possible to stabilize the collapse load sufficiently low while ensuring sufficient heat resistance, and to operate in the event of a collision accident. It is possible to effectively ensure the safety of persons.

[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. 1, showing a state during assembly.

FIG. 4 is a sectional view similar to FIG. 1, showing a state in which the entire length is shortened.

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

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

FIG. 7 is a sectional view similar to FIG. 2, showing a fourth embodiment of the present invention.

FIG. 8 is a sectional view similar to FIG. 1, showing a fifth embodiment of the present invention.

FIG. 9 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. 10 is a vertical sectional side view showing a first example of a conventional structure.

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

FIG. 12 is a vertical sectional side view showing a second example of the conventional structure.

13 is a cross-sectional view taken along line CC of FIG.

FIG. 14 is a half-section vertical side view showing a third example of the conventional structure.

15 is a cross-sectional view taken along the line DD 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 Shock absorption type steering shaft 19 Through hole 20 Small diameter part 21 Steel ball 22 Valley 23 Clearance space 24 Through hole 25 Flat surface 26 Radial clearance 27 Cage 28 Ball 29 Pocket 30 Shock absorption type steering shaft 31 Roller 32 Needle 33 Recessed groove 34 Recessed groove 35 Uneven part 36 Uneven part

Claims (1)

[Scope of utility model registration request] 1. A cylindrical outer shaft, an inner shaft that is combined with the outer shaft by freely displacing only in the axial direction, and between an outer peripheral surface of the inner shaft and an inner peripheral surface of the outer shaft. A radial gap provided in the cage, a retainer inserted in the radial gap so as to be displaceable in the axial direction, and freely rollable in the retainer at at least two positions apart from each other in the axial direction. A shock-absorbing type in which the outer shaft and the inner shaft are combined by strongly contacting the inner peripheral surface of the outer shaft and the outer peripheral surface of the inner shaft with the rolling element. Steering shaft.