JPH0534302Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention relates to a structure of a lower bushing for preventing assembly failure of the lower bushing in a steering device.

(Prior art) Generally, when an excessive upward thrust load is applied from the gearbox side or an excessive downward thrust load is applied from the steering wheel side to the steering column of a steering device, a structure that can absorb these loads is developed. It's summery.

That is, as shown in FIG. 7, a cylindrical lower bush 4 made of resin is interposed between the lower tube 1 and the upper tube 3 of the steering column 2. The upper tube 3 and the lower bush 4 are positioned by the protrusion 7 of the lower bush 4, and the lower tube 1 and the lower bush 4 are positioned by the protrusion 5 of the lower bush 4, respectively.

In this state, when an excessive push-down load is applied from the steering wheel side on the right side in the figure, the attachment tube 3 shears the protrusion 7, and then moves to the left side in the figure while receiving frictional force from the lower bush 4. This will absorb the downward thrust load. Furthermore, when an excessive thrust load is applied from the gearbox side, the main shaft 6 moves by a stroke S, as is generally known, so that the load can be absorbed.

(Problems to be Solved by the Invention) When assembling such a conventional structure, first the lower tube 1 and the lower bush 4 are assembled, and then the uppipe tube 3 is press-fitted into the lower bush 4. This Atsupachi Yuube 3
In order to prevent the protrusion 7 from interfering with the press-fitting of the lower bushing 4 into the lower bushing 4, the outer periphery of the lower bushing 4 is generally thinned to provide a gap 9, as shown in FIG. Since this gap 9 is removed by the height of the protrusion 7, the attachment tube 3 can be easily press-fitted. However, since the height of the protrusion 7 cannot be made larger than the above-mentioned gap 9, and since the protrusion 7 has a hemispherical shape, if the attachment tube 3 is inadvertently press-fitted, the engagement hole of the attachment hole 3
This causes the protrusion to go over the protrusion 7 and enter deeper, resulting in a shift in the longitudinal positional relationship. For this reason, conventionally, it is necessary to assemble the assembly while manually confirming whether or not the protrusion 7 and the engagement hole 8 are properly engaged each time.

(Means for Solving the Problems) In order to solve the above problems, the present invention is configured as follows.

In other words, the cylindrical lower bush interposed between the inner periphery of the lower tube and the outer periphery of the upper tube of the steering column engages with the engagement hole of the upper tube with the protrusion formed integrally on its inner circumference engaged with the upper tube. The projection is positioned in the axial direction of the projection, and when an excessive load is applied to the projection in the axial direction, the projection is sheared,
In a steering device configured such that the excessive load is absorbed by the shear load and the subsequent sliding resistance between the uppipe tube and the lower bush, the lower bush A stopper is formed that can receive the end face of the attachment tube when the projection and the engagement hole of the attachment tube are engaged, and is sheared by a load that is less than the shearing load of the projection.

(Example) Hereinafter, an example of the present invention will be specifically described with reference to FIGS. 1 to 6.

First Embodiment First, in FIGS. 1 to 3, the lower bush 4 is made of a resin material and is formed into a substantially cylindrical shape in this example. And, on the outer periphery of this lower bush 4,
As shown in FIG. 3, the engagement hole 11 of the lower tube 1
Three protrusions 5 are formed for engaging with and maintaining mutual positional relationship.

Furthermore, a protrusion 7 is formed on the inner circumferential surface of the lower bush 4 to engage with an engagement hole 8 of an attachment tube 3, which will be described later. In this example, the protrusion 7 is formed into a hemispherical shape, and one protrusion 7 is formed near the right end of the lower bush 4 in the drawing.

Subsequently, the main parts of this embodiment will be explained mainly with reference to FIGS. 3 and 4. Said lower bush 4
A stopper 10 is formed near the left end of the inner circumferential surface in the drawing. As shown in FIG. 3, this stopper 10 is formed so that the distance from the projection 7 is the same as the distance l from the engagement hole 8 of the upper tube 3 to the end surface of the upper tube 3. Further, when an excessive downward thrust load is applied from the steering wheel side, the stopper 10 is sheared at the same time as the protrusion 7, and at this time, the protrusion 7
30Kg to avoid excessive shearing force than the shearing force of
It is set so that it can be sheared with a certain amount of force. The specific shape of the stopper 10 for realizing this is a rectangular shape with a width of 3 mm and a thickness of 2.5 mm. Note that the opening height is set to an appropriate height.

On the other hand, the stopper 10 is formed at a location where the inner periphery of the lower bush 4 and the outer periphery of the upper tube 3 touch, and at a position in the same phase as the projection 7 in the circumferential direction.

According to the above structure, since the stopper 10 is formed on the lower bush 4, the assembly of the upper bush 3 and the lower bush 4 in the axial direction can be accomplished by simply inserting the upper bush 3 into the lower bush 4 until it comes into contact with the stopper 10. The position can be determined with high precision. Therefore, as in the conventional case, the protrusion 7 of the lower bush 4 fits into the engagement hole 11 of the attachment tube 3.
There is no need to manually check whether or not it has engaged with the Atsupati Yubu 3 during assembly.
assembly can be automated.

Further, the stopper 10 is configured to press down on the end face of the uppipe tube 3 and is located at a point where the inner periphery of the lower bush 4 and the outer circumference of the uppatch tube 3 touch, so that when an excessive load is applied to the atpatch tube 3, the stopper 10 presses the end face of the uppatch tube 3. This ensures shearing is done from the root, and the variation in shearing load at this time is reduced.

Second Embodiment In the case of the first embodiment described above, by providing the stopper 10, it is possible to prevent the uppipe tube 3 from shifting in the axial direction with respect to the lower bush 4. However, since the protrusion 7 of the lower bush 4 has a hemispherical shape, when rotational force is applied to the attachment hole 3 during transportation of the steering column, for example, the engagement hole 7 of the attachment hole 3
rotates over the protrusion 7 of the lower bush 4,
There is a risk that a phase shift will occur between the uppipe tube 3 and the lower bush 4.

Therefore, in the second embodiment shown in FIGS. 5 and 6, a cylindrical projection 20 is used in place of the hemispherical projection 7 in the first embodiment. As a result, the engagement of the attachment hole 8 of the attachment tube 3 with respect to the engagement hole 8 becomes large, and this engagement hole 8
If the rotation speed exceeds 0, the problems that occur will be prevented. Note that the projection 20 is formed with a tapered surface 20a on the insertion side of the attachment tube 3 to facilitate insertion of the attachment tube 3.

Further, the protrusions 7, 20 of the lower bush 4 in the first and second embodiments are formed at locations where the inner circumferential surface of the lower bush 4 is in surface contact with the outer circumferential surface of the attachment tube 3. (See Figure 4 or Figure 6). This stabilizes the shearing load on the protrusions 7, 20 caused by the aforementioned impact load, and for example, the protrusions 7, 20 are placed in locations where the inner circumferential surface of the lower bush 4 and the outer circumferential surface of the attachment tube 3 are not in contact. It is possible to avoid variations in shearing load when formed, or situations in which shearing does not occur even when a predetermined impact load is reached.

(Effects of the invention) In this way, the present invention is capable of simultaneously shearing the protrusion of the lower bush due to an excessive load applied to the protrusion, and at the same time controlling the insertion position of the protrusion relative to the lower bush by the stopper, which is sheared by a load less than the shearing load of the protrusion. Therefore, when assembling the attachment tube to the lower bush, simply insert the attachment tube until the end face of the attachment tube is received by the stopper, and the engagement hole of the attachment tube and the protrusion of the lower bush can be properly engaged. Furthermore, the presence of this stopper does not adversely affect the load absorption characteristics due to the shearing load of the protrusion and the sliding resistance of the lower bush.

[Brief explanation of drawings]

Figures 1 to 6 of the drawings show an embodiment of the present invention. Figure 1 is a front view showing a lower bushing, Figure 2 is a cross-sectional view taken along the line - - of Figure 1, and Figure 3 is a lower bushing and an upper bush. FIG. 4 is a sectional view taken along the - line in FIG. 3, and FIG. 5 is a sectional view showing a different embodiment.
A sectional view shown in correspondence with the figure.
It is a sectional view taken along the line - in the figure. FIG. 7 is a side sectional view showing a conventional steering column. 3... Atsupachiyubu, 4... Roarbutsuyu,
10...Lower bush stopper.

Claims (1)

[Claim for Utility Model Registration] A cylindrical lower bush interposed between the inner circumference of the lower tube and the outer circumference of the upper tube of the steering column has a protrusion integrally formed on its inner circumference that engages with the engagement hole of the upper tube. In this state, the protrusion is positioned in the axial direction relative to the upper bush, and when an excessive load in the axial direction is applied to the upper bush, the protrusion is sheared, and the shear load and subsequent sliding resistance between the upper bush and the lower bush. In the steering device configured such that the excessive load is absorbed by
A stopper is formed that can receive the end face of the attachment tube in a state where the projection of the lower bushing and the engagement hole of the attachment tube are engaged, and is sheared by a load that is less than the shearing load of the projection. A structure of a lower bushing in a steering device characterized by: