JPH09317725A - Connection structure for rotary shaft - Google Patents

Abstract

PROBLEM TO BE SOLVED: To sufficiently increase a torque generated by relative rotation between an exterior shaft and an interior shaft by sufficiently increasing torsional rigidity at a connection part between the shafts. SOLUTION: An exterior shaft 11 has a hole 11a of a non-circular sectional area. An interior shaft 12 has a shaft part 12a fitted to the hole 11a of the exterior shaft 11 in a slidable and troque-transmittable manner in the axial direction. An elastic body 13 is arranged on a fitting part between the shafts 11 and 12 for making one part of the shaft part 12a of the interior shaft to be in press-contact with a part of the hole 11a of the exterior shaft. The elastic body 13 is engaged with the shaft part 12a of the interior shaft 12 or a flat surface formed on the hole 11a of the exterior shaft 11 at its circumferential edge 13a. It is also engaged with the hole 11a of the exterior shaft 11 or the shaft part 12a of the interior shaft 12 at its projection 13b formed on its circumferential center portion.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotating shaft coupling structure employed as, for example, a steering shaft of an automobile.

[0002]

2. Description of the Related Art As one of the connecting structures for rotating shafts,
An exterior shaft having a hole with a non-circular cross section, an interior shaft having a shaft portion slidably fitted in the hole portion of the exterior shaft and capable of transmitting torque, and a fitting portion of both shafts. Some of them include an elastic body that is interposed to press a part of the shaft portion of the inner shaft into a part of the hole portion of the outer shaft.
As disclosed in Japanese Unexamined Patent Publication No. 2 (1994), a wavy leaf spring in the axial direction or a U-shaped leaf spring in the circumferential direction is adopted as the elastic body.

[0003]

In the above publication, in the joint structure of the rotary shaft which employs the wavy plate spring in the axial direction as the elastic body, the shaft of the internal shaft is formed at the peak of the wavy plate spring. Of the outer shaft or the shaft of the interior shaft is engaged with the hole of the exterior shaft or the shaft of the interior shaft at the valley of the wavy leaf spring, and each engaging portion is linear in the circumferential direction. Has become. Therefore, in this coupling structure, it is difficult to sufficiently increase the torsional rigidity at the coupling portion between the outer shaft and the inner shaft, and the torque that causes relative rotation (rotation rattling) between both shafts (rotation rattling torque). ) Is difficult to raise sufficiently.

Further, in the rotating shaft coupling structure which employs a U-shaped leaf spring assembled around the inner shaft as an elastic body, the hole portion of the outer shaft is formed at the central portion of the U-shaped leaf spring. , And the ends of the U-shaped leaf spring are engaged with the shaft portion of the internal shaft, so that the U-shaped leaf spring is easily expanded and deformed. Therefore, even in this coupling structure, it is difficult to sufficiently increase the torsional rigidity at the coupling portion between the outer shaft and the inner shaft, and torque (rotational rattling torque) that causes relative rotation (rotational rattling) between both shafts. ) Is difficult to raise sufficiently.

[0005]

In order to solve the above problems, in the first invention (the invention of claim 1), an exterior shaft having a hole portion having a non-circular cross section, and an axis in the hole portion of the exterior shaft are provided. The internal shaft having a shaft portion that is slidable in the direction and fitted so that torque can be transmitted, and a part of the shaft portion of the internal shaft that is interposed between the fitting portions of these shafts In a coupling structure of a rotating shaft, comprising: an elastic body that is brought into pressure contact with a part of the elastic body, the elastic body is engaged at its circumferential edge portion with a flat surface portion formed in a shaft portion of the internal shaft or a hole portion of the external shaft, and It is characterized in that at least one convex portion formed in the central portion in the circumferential direction engages with the hole portion of the exterior shaft or the shaft portion of the interior shaft.

In the second invention (the invention of claim 2), an exterior shaft having a hole, and a shaft fitted in the hole of the exterior shaft so as to be slidable in the axial direction and capable of transmitting torque. In a joint structure of a rotary shaft comprising an inner shaft having a portion and an elastic body interposed in a fitting portion of the both shafts, the elastic body has a peripheral portion at the shaft portion of the inner shaft or the outer shaft. It is characterized in that it is configured to engage with the flat surface portion formed in the hole portion and to engage with the hole portion of the outer shaft or the shaft portion of the inner shaft by at least one convex portion formed in the central portion.

In each of the above-mentioned inventions, it is preferable that the projection has a shape extending in the axial direction formed by bulging the central portion of the flat plate spring.

[0008]

In the rotating shaft coupling structure according to the first aspect of the present invention, the elastic body engages with the flat portion formed at the axial portion of the inner shaft or the hole of the outer shaft at the circumferential edge thereof. At least one convex portion formed at the central portion in the circumferential direction engages with the hole portion of the exterior shaft or the shaft portion of the interior shaft, and both shafts can be pressed against each other by the elastic body, and at the same time, the elastic body Since the load transmitted between both shafts can be received at the circumferential edge of the shaft, the torsional rigidity at the joint between the outer shaft and the inner shaft can be made sufficiently high, and the relative rotation between both shafts can be achieved. It is possible to sufficiently increase the torque (rotational backlash generated torque) generated by.

Further, in the rotating shaft coupling structure according to the second aspect of the invention, the elastic body engages with the flat portion formed at the peripheral portion of the shaft portion of the inner shaft or the hole portion of the outer shaft and at the central portion. At least one convex portion formed is configured to engage with the hole portion of the outer shaft or the shaft portion of the inner shaft, and the entire edge portion of the elastic body can receive the transmission load between both shafts, thus improving efficiency. The spring constant of the elastic body can be increased well.

If the convex portion of the elastic body has a shape extending in the axial direction formed by bulging the central portion of the flat plate-shaped leaf spring, the convex portion forms a rib on the elastic body, which improves efficiency. The spring constant of the elastic body can be increased well.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. 1 to 3 show an example in which a rotating shaft coupling structure according to the present invention is applied to a steering shaft 10. In this steering shaft 10, an exterior shaft 11 and an interior shaft 12 are slidable in the axial direction and torque is applied. It is fitted so as to be able to be transmitted, and a flat plate-shaped leaf spring 13 is interposed in this fitting portion in a slightly compressed and deformed state.

The outer shaft 11 has a hole 1 having a hexagonal cross section.
1a is a shaft having a universal joint 14 at one end
Are assembled integrally. The inner shaft 12 has a shaft portion 12a having a hexagonal cross section that is fitted in a hole portion 11a of the outer shaft 11 so as to be slidable in the axial direction and capable of transmitting torque, and a universal joint 15 is integrally formed at one end thereof. And a notch 12b for accommodating the leaf spring 13 is formed in the shaft portion 12a.

As shown in FIGS. 2 to 4, the leaf spring 13 is bulged in a bag shape except for the peripheral edge portion 13a of a rectangular flat plate, and is positioned at a central portion in the circumferential direction when being interposed. A trapezoidal convex portion 13b extending in the axial direction is formed, and is inserted in the fitting portion of both shafts 11 and 12 in a state of being housed in the notch 12b of the internal shaft 12, and the axial portion of the internal shaft 12 is formed. A part of 12b (A and B surfaces in FIG. 3) is pressed against a part of the hole 11a (C and D surfaces in FIG. 3) of the outer shaft 11, and the shaft portion 12a of the inner shaft 12 is attached to the shaft portion 12a of the inner shaft 12 at the peripheral edge 13a. It engages with the flat portion of the formed notch 12b, and engages with the hole portion 11b of the exterior shaft 11 by the convex portion 13b. In the leaf spring 13, the entire edge portion can receive the load transmitted between the shafts 11 and 12, and the convex portion 13b that is bulged forms a rib on the leaf spring 13 (with respect to the peripheral portion 13a). Since the structure which is not easily deformed and can withstand a large load is formed, the leaf spring 1 can be efficiently used.
The spring constant of 3 can be increased.

In the present embodiment constructed as described above, the leaf spring 13 has its peripheral edge portion 13a at the inner shaft 1 thereof.
It is configured such that the flat portion of the notch 12b formed in the second shaft portion 12a is engaged and the convex portion 13b is engaged with the hole portion 11a of the exterior shaft 11, and the leaf spring 13 allows both shafts 1
Since 1 and 12 can be pressed against each other and the load transmitted between both shafts 11 and 12 can be received at the circumferential edge portion of the leaf spring 13, the joint portion between the exterior shaft 11 and the interior shaft 12 can be It is possible to sufficiently increase the torsional rigidity, and it is possible to sufficiently increase the torque (rotational backlash generation torque) that causes relative rotation between the shafts. Further, since the leaf spring 13 can be compactly accommodated in a small mounting space between the exterior shaft 11 and the interior shaft 12, the structure of the joint between the two shafts 11, 12 can be made extremely simple and compact.

In the above embodiment, both shafts 1
Although the cross-sectional shape of the joints 1 and 12 is hexagonal, the cross-sectional shape is not limited to hexagonal as long as it is non-circular. Also,
In the above embodiment, the leaf spring 13 is adopted as an elastic body which is interposed between the fitting portions of the shafts 11 and 12 and presses a part of the shaft portion 12a of the inner shaft 12 into a part of the hole portion 11a of the outer shaft 11. However, this elastic body is not limited to the leaf spring 13 and can be appropriately changed. Also,
In the above embodiment, the peripheral portion 13a of the leaf spring 13 is engaged with the shaft portion 12a of the internal shaft 12, and
Although the convex portion 13b is engaged with the hole portion 11b of the exterior shaft 11, the peripheral portion 13a of the leaf spring 13 is engaged with the hole portion 11b of the exterior shaft 11, and the convex portion 13b is formed.
Can be carried out by engaging with the shaft portion 12a of the internal shaft 12 (in FIG. 3, the leaf spring 13 is reversed upside down).

Further, in the above embodiment, the trapezoidal convex portion 13b extending in the axial direction at the portion which becomes the central portion in the circumferential direction when interposing is formed by bulging in a bag shape except for the peripheral portion 13a of the rectangular flat plate. However, in place of the trapezoidal protrusion 13b, two linear protrusions 13b (three or more lines) extending in the axial direction are used instead of the trapezoidal protrusion 13b. It is also possible to form a convex portion). The central portion between the linear protrusions 13b contributes to increase the rigidity of the leaf spring 13, and as shown in FIG. 5, the shafts 11 and 12 are not in contact with each other (rectangular flat plate). It is preferable that only the peripheral edge portion 13a of the above is engaged with the flat surface portion of the notch 12b formed in the shaft portion 12a of the internal shaft 12). According to this configuration, the spring rigidity can be adjusted without being greatly affected by the stress, as compared with the case where the spring rigidity is adjusted by the plate thickness.

In each of the above-described embodiments, the present invention is implemented as a structure in which the entire periphery of the convex portion 13b is continuous with the peripheral edge portion 13a. However, a slit or an opening is provided at the axial end portion or the circumferential end portion of the convex portion 13b. It is also possible to implement the present invention as a formed structure.

[Brief description of drawings]

FIG. 1 is a partially omitted front view showing an example of a steering shaft that implements a rotating shaft coupling structure according to the present invention.

FIG. 2 is a vertical sectional front view of a main part of FIG.

FIG. 3 is a sectional view taken along line 3-3 in FIG. 2;

4 is a perspective view of the leaf spring shown in FIGS. 2 and 3. FIG.

FIG. 5 is a cross-sectional view corresponding to FIG. 3 showing another embodiment of the present invention.

6 is a perspective view of the leaf spring shown in FIG.

[Explanation of symbols]

10: Steering shaft, 11: Exterior shaft, 1
1a ... Hole, 12 ... Interior shaft, 12a ... Shaft, 12
b ... notch, 13 ... leaf spring (elastic body), 13a ... peripheral portion,
13b ... convex portion.

Claims (3)

[Claims] 1. An exterior shaft having a hole having a non-circular cross section, an interior shaft having a shaft portion slidably fitted in the hole of the exterior shaft and capable of transmitting torque, and both shafts. In a joint structure of a rotary shaft, wherein the elastic body is interposed in the fitting portion of the inner shaft and presses a part of a shaft portion of the inner shaft to a part of a hole portion of the outer shaft. Part of the outer shaft or the shaft of the outer shaft is engaged with a flat part formed in the shaft part of the inner shaft or the hole of the outer shaft, and the hole part of the outer shaft or the shaft of the inner shaft is formed by at least one convex part formed in the circumferential center part. A rotating shaft coupling structure, characterized in that it is configured to engage with a portion. 2. An exterior shaft having a hole, an interior shaft having a shaft fitted in the hole of the exterior shaft so as to be slidable in the axial direction and capable of transmitting torque, and a fitting portion of both shafts. In a connecting structure of a rotating shaft including an elastic body interposed between the elastic body and the central portion, the elastic body is engaged at its peripheral portion with a flat surface portion formed in a shaft portion of the internal shaft or a hole portion of the external shaft, and in the center. A rotary shaft coupling structure, characterized in that at least one convex portion formed in the portion is engaged with the hole portion of the exterior shaft or the shaft portion of the interior shaft. 3. The coupling structure for a rotary shaft according to claim 1, wherein the convex portion has a shape extending in the axial direction formed by bulging the central portion of the flat plate spring.