JP2021115997A - Propeller shaft - Google Patents

Abstract

To provide a propeller shaft that can reduce a surface pressure in a meshing part.SOLUTION: A propeller shaft includes: a first shaft member including a cylindrical part extending in an axial direction, a first spline tooth disposed at an outer peripheral surface of the cylindrical part and a second spline tooth disposed at an inner peripheral surface of the cylindrical part; and a second shaft member including a tubular part extending in the axial direction, a shaft core part disposed coaxially inside the tubular part and extending in the axial direction, a third spline tooth disposed at an inner peripheral surface of the tubular part and meshing with the first spline tooth and a fourth spline tooth disposed at an outer peripheral surface of the shaft core part and meshing with the second spline tooth.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to propeller shafts.

For example, the power of a prime mover such as an internal combustion engine (engine) mounted on a vehicle is transmitted to a drive wheel via a clutch, a transmission, a transfer, a propeller shaft, a differential, and an axle.

While the vehicle is running, the transfer moves integrally with the vehicle body, while the differential moves relative to the vehicle body. This changes the distance between the transfer and the differential. A telescopic propeller shaft that expands and contracts in response to this change in distance is known.

For example, Patent Document 1 discloses a telescopic propeller shaft including a first shaft member having a male spline on the outer peripheral surface and a second shaft member having a female spline on the inner peripheral surface that meshes with the male spline. ing. For example, the first shaft member is connected to the transfer and the second shaft member is connected to the differential. When the distance between the transfer and the differential changes, the male and female splines slide against each other, causing the propeller shaft to expand and contract. Further, the power of the prime mover is transmitted from the transfer to the differential via the meshing portion (contact portion) in which the male spline and the female spline mesh with each other.

For example, when the rear overhang length, which is the length from the drive wheels (rear wheels) to the rear end of the vehicle body in the front-rear direction of the vehicle, is long, the rear end of the vehicle body easily protrudes from the lane, especially when the vehicle is turned left or right. It is difficult to drive, and the rear end of the vehicle body is easily rubbed by the slope, especially when the vehicle runs on the slope.

It is preferable to make the rear overhang length as short as possible in order to facilitate driving when the vehicle is turned left or right and to prevent the rear end of the vehicle body from being rubbed by a slope. When shortening the rear overhang length, in the rear engine bus where the engine is located at the rear end of the vehicle body, it is necessary to shorten the distance between the transfer and the differential, and it is necessary to shorten the propeller shaft. ..

Further, for example, in the case of an EV (Electric Vehicle) equipped with one or more batteries for supplying power to a motor which is a prime mover, or an electric vehicle (so-called xEV) such as an HEV (Hybrid Electric Vehicle), the layout of the battery In order to increase the degree of freedom, it is preferable that the propeller shaft when placed around the battery is as short as possible.

Japanese Unexamined Patent Publication No. 2014-20503

By the way, when trying to shorten the propeller shaft, if the axial length (engagement length) of the meshing portion is shortened, the area (contact area) of the meshing portion where surface pressure is generated corresponds to the shortening of the meshing length. It becomes smaller. When the contact area becomes small, the surface pressure of the meshing portion increases, causing poor sliding of the meshing portion, and the telescopic propeller shaft may not be established.

An object of the present disclosure is to provide a propeller shaft capable of reducing the surface pressure of the meshing portion.

In order to achieve the above object, the propeller shaft in the present disclosure is
A first having a tubular portion extending in the axial direction, a first spline tooth arranged on the outer peripheral surface of the tubular portion, and a second spline tooth arranged on the inner peripheral surface of the tubular portion. Shaft member and
A tubular portion extending in the axial direction, a shaft core portion coaxially arranged in the tubular portion and extending in the axial direction, and an inner peripheral surface of the tubular portion, and the first spline tooth. A second shaft member having a third spline tooth that meshes with a fourth spline tooth that is arranged on the outer peripheral surface of the shaft core portion and meshes with the second spline tooth.
Be prepared.

According to the propeller shaft of the present disclosure, the surface pressure of the meshing portion can be reduced.

FIG. 1 is a partial vertical sectional view of a propeller shaft according to an embodiment of the present disclosure. FIG. 2 is a partial cross-sectional view of the propeller shaft. FIG. 3 is a linear development of a partial cross section of the propeller shaft.

Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.
FIG. 1 is a partial vertical sectional view of the propeller shaft 1 according to the embodiment of the present disclosure. FIG. 2 is a partial cross-sectional view of the propeller shaft 1. In FIG. 1, the X-axis and the Y-axis are drawn. In FIG. 1, the left-right direction is referred to as the X direction or the axial direction, the left direction is referred to as "+ X direction" or one side in the axial direction, and the right direction is referred to as "-X direction" or the other side in the axial direction. Further, in FIG. 1, the vertical direction is referred to as the Y direction or the radial direction, the direction away from the X axis in the Y direction is referred to as "+ Y direction" or the radial outer direction, and the direction approaching the X axis from the Y direction is referred to as "-Y direction". Or it is called the inner side in the radial direction.

As shown in FIGS. 1 and 2, the propeller shaft 1 includes a first shaft member 10 and a second shaft member 20. For example, one of the first shaft member 10 and the second shaft member 20 is connected to the transfer, and the other member is differentially connected. For example, carbon steel is used as the material of the first shaft member 10 and the second shaft member 20.

The first shaft member 10 is arranged on the shaft portion 11, the tubular portion 12 extending from the axial one side (+ X direction) end of the shaft portion 11 to the axial one side, and the outer peripheral surface 14 of the tubular portion 12. It has a first spline tooth 31 to be formed and a second spline tooth 32 arranged on the inner peripheral surface 16 of the tubular portion 12.

The first spline tooth 31 projects radially outward (+ Y direction) from the outer peripheral surface 14. For example, a predetermined number of Za first spline teeth 31 are arranged on the outer peripheral surface 14 at equal intervals in the circumferential direction. The first spline tooth 31 has a predetermined size (module Ma). The first spline tooth 31 is, for example, an involute spline tooth.

The second spline tooth 32 projects radially inward (−Y direction) from the inner peripheral surface 16. For example, a predetermined number of Zb of the second spline teeth 32 are arranged on the inner peripheral surface 16 at equal intervals in the circumferential direction. The second spline tooth 32 has a predetermined size (module Mb). The second spline tooth 32 is, for example, an involute spline tooth.

The second shaft member 20 has a shaft portion 21, a tubular portion 22A, a shaft core portion 22B, a third spline tooth 33, and a fourth spline tooth 34.

The tubular portion 22A extends from the axial other side (−X direction) end of the shaft portion 21 to the axial other side. The shaft core portion 22B is coaxially arranged inside the tubular portion 22A in the radial direction (−Y direction), and extends from the other side end in the axial direction of the shaft portion 21 to the other side in the axial direction.

The third spline tooth 33 is recessed radially outward (+ Y direction) from the inner peripheral surface 26 of the tubular portion 22A. A plurality of predetermined Zas (the same number of teeth as the first spline teeth 31) are arranged on the inner peripheral surface 26 of the third spline teeth 33 at equal intervals in the circumferential direction. The third spline tooth 33 has a predetermined size (module Ma: the same size as the first spline tooth 31). The third spline tooth 33 is, for example, an involute spline tooth. The first spline tooth 31 and the third spline tooth 33 mesh with each other so as to slide with each other. FIG. 1 schematically shows meshing portions 311, 331 in which the first spline teeth 31 and the third spline teeth 33 mesh with each other by diagonal grid hatching. Further, FIG. 1 shows the axial length La (engagement length) of the meshing portions 311, 331.

The fourth spline tooth 34 is recessed in the radial direction (−Y direction) from the outer peripheral surface 24 of the shaft core portion 22B. A plurality of predetermined Zb (the same number of teeth as the second spline tooth 32) are arranged on the outer peripheral surface 24 of the fourth spline tooth 34 at equal intervals in the circumferential direction. The fourth spline tooth 34 has a predetermined size (module Mb: the same size as the second spline tooth 32). The fourth spline tooth 34 is, for example, an involute spline tooth. The second spline tooth 32 and the fourth spline tooth 34 mesh with each other so that the first shaft member 10 and the second shaft member 20 slide in the axial direction with each other. FIG. 1 schematically shows meshing portions 321 and 341 in which the second spline teeth 32 and the fourth spline teeth 34 mesh with each other by diagonal grid hatching. Further, FIG. 1 shows the meshing length Lb. Further, FIG. 1 shows a stroke allowable length Ls that allows the first shaft member 10 and the second shaft member 20 to slide. As shown in FIG. 1, the meshing length La and the meshing length Lb are the same.

In the modules Ma and Mb, the surface pressure Pa of the meshing portions 311, 331 (contact surface) where the first spline tooth 31 and the third spline tooth 33 mesh with each other, and the second spline tooth 32 and the fourth spline tooth 34 are mutual. The surface pressure Pb of the meshing portions 321 and 341 (contact surfaces) is set to be equal to each other.

Generally, the surface pressure P of the contact surface is expressed by the following equation (1).
P = 2T / (η * H * L * Z * d)… (1)
Here, T is the shaft torque, η is the meshing ratio, H is the meshing tooth length, L is the meshing length, Z is the number of teeth in contact, and d is the pitch circle diameter.

Therefore, the surface pressures Pa and Pb are represented by the following equations (2) and (3).
Pa = 2Ta / (ηa * Ha * La * Za * da)… (2)
Pb = 2Tb / (ηb * Hb * Lb * Zb * db)… (3)
Here, Ta and Tb are axial torques, ηa and ηb are meshing ratios, Ha and Hb are meshing tooth lengths, La and Lb are meshing lengths, Za and Zb are the number of teeth in contact, and da and db are pitch circles. The diameter.

In order for the surface pressures Pa and Pb to be equal (Pa = Pb), each parameter may be set so that the following equation (4) holds.
2Ta / (ηa * Ha * La * Za * da) = 2Tb / (ηb * Hb * Lb * Zb * db)… (4)

That is, in the modules Ma and Mb, each parameter such as the number of teeth Za and Zb and the pitch circle diameters da and db is set so that the above equation (4) is satisfied.

The propeller shaft 1 in the above embodiment includes a tubular portion 12 extending in the axial direction (X direction), a first spline tooth 31 arranged on the outer peripheral surface 14 of the tubular portion 12, and a tubular portion 12. A first shaft member 10 having a second spline tooth 32 arranged on the inner peripheral surface 16, a tubular portion 22A extending in the axial direction, and a tubular portion 22A arranged coaxially in the tubular portion 22A and extending in the axial direction. The existing shaft core portion 22B, the third spline tooth 33 arranged on the inner peripheral surface 26 of the tubular portion 22A and meshing with the first spline tooth 31, and the second spline tooth arranged on the outer peripheral surface 24 of the shaft core portion 22B. A second shaft member 20 having a fourth spline tooth 34 that meshes with 32 is provided.

With the above configuration, meshing portions 311,331 (contact portions) in which the first spline teeth 31 and the third spline teeth 33 mesh with each other are arranged on the outer side in the radial direction, and the second spline teeth 32 and the fourth spline teeth 33 on the inner side in the radial direction. Engagement portions 321 and 341 that mesh with 34 are arranged. As a result, the area (contact area) of the meshing portion where the surface pressure is generated can be increased, so that the surface pressure of the meshing portion can be reduced.

Further, in the present embodiment, the modules Ma and Mb are set so that the surface pressure Pa of the meshing portions 311, 331 and the surface pressure Pb of the meshing portions 321 and 341 are equal. As a result, it is possible to increase the contact area of both the meshing portions 311, 331 and the meshing portions 321, 341 without bias. As a result, the contact area can be efficiently increased, so that the surface pressure of the meshing portion can be further reduced.

(Modification example)
Next, a modified example of the present embodiment will be described with reference to FIG. The tubular portion 12 of the first shaft member 10 and the tubular portion 22A and the shaft core portion 22B of the second shaft member 20 are hardened in order to increase the mechanical strength of the first spline teeth 31 and the like. By the way, in quenching, there is a problem that cracks are likely to occur in a sudden change in wall thickness.

FIG. 3 is a linear development of a partial cross section of the tubular portion 12. As shown in FIG. 3, in the modified example, the tubular portion 12 has a shape such that the wall thickness becomes substantially constant in the circumferential direction. Specifically, the pitch in the circumferential direction of the first spline tooth 31 is the same as the pitch in the circumferential direction of the second spline tooth 32. Further, the first spline tooth 31 and the second spline tooth 32 are arranged so as to be displaced from each other by a predetermined amount in the circumferential direction, so that the tooth tip of the first spline tooth 31 and the tooth bottom of the second spline tooth 32 are separated from each other. The distance is the same as the distance between the root of the first spline tooth 31 and the tip of the second spline tooth 32. As described above, the tubular portion 12 has a shape such that the wall thickness becomes substantially constant in the circumferential direction. As a result, cracking is unlikely to occur when quenching.

In addition, the above embodiments are merely examples of embodiment of the present disclosure, and the technical scope of the present disclosure should not be construed in a limited manner by these. .. That is, the present disclosure can be implemented in various forms without departing from its gist or its main features.

In the above embodiment, the modules Ma and Mb may be the same. In this case, the modules Ma and Mb may be set with parameters such as the number of teeth Za and Zb and the pitch circle diameters da and db so that they are the same as each other. By making the modules Ma and Mb the same as each other, it is possible to use the same tool when processing spline teeth.

Further, in the above embodiment, the first spline tooth 31 protrudes radially outward (+ Y direction) from the outer peripheral surface 14, but the present disclosure is not limited to this, and the present disclosure is not limited to this, and the present disclosure is not limited to this, and the outer peripheral surface 14 is radially inward (−Y direction). ), And in the above embodiment, the second spline tooth 32 protrudes radially inward from the inner peripheral surface 16, but the present disclosure is not limited to this, and the present disclosure is not limited to this. It may be recessed outward in the radial direction.

Further, in the above embodiment, the first to fourth spline teeth 31, 32, 33, 34 are involute spline teeth, but the present disclosure is not limited to this, and the present disclosure is not limited to this, and a square shape having two tooth surfaces parallel to each other. It may be a spline tooth.

Further, the propeller shaft 1 according to the above embodiment includes a double spline having a first meshing portion 311,331 and a second meshing portion 321 and 341. However, the present disclosure is not limited to this, and the propeller shaft 1 has a triple mesh having a third meshing portion radially outside the first meshing portion 311,331 or radially inside the second meshing portion 321 and 341. It may be provided with splines, or may be provided with four or more splines.

The present disclosure is suitably used for a power transmission system using a propeller shaft, which is required to reduce the surface pressure of the meshing portion.

10 1st shaft member 11 Shaft part 12 Cylindrical part 14 Outer peripheral surface 16 Inner peripheral surface 20 2nd shaft member 21 Shaft part 22A Tubular part 22B Shaft core part 24 Outer peripheral surface 26 Inner peripheral surface 31 1st spline tooth 32 2nd spline Tooth 33 3rd spline tooth 34 4th spline tooth 311, 3211, 331, 341 Engagement part

Claims (5)

A first having a tubular portion extending in the axial direction, a first spline tooth arranged on the outer peripheral surface of the tubular portion, and a second spline tooth arranged on the inner peripheral surface of the tubular portion. Shaft member and
A tubular portion extending in the axial direction, a shaft core portion coaxially arranged in the tubular portion and extending in the axial direction, and an inner peripheral surface of the tubular portion, and the first spline tooth. A second shaft member having a third spline tooth that meshes with a fourth spline tooth that is arranged on the outer peripheral surface of the shaft core portion and meshes with the second spline tooth.
Propeller shaft. In the first to fourth spline tooth modules, the surface pressure of the meshing portion where the first spline tooth and the third spline tooth mesh with each other and the second spline tooth and the fourth spline tooth mesh with each other. It is set so that the surface pressure of the meshing part is even.
The propeller shaft according to claim 1. The first spline tooth projects radially outward from the outer peripheral surface or recesses radially inward from the outer peripheral surface.
The propeller shaft according to claim 1 or 2. The second spline tooth projects radially inward from the inner peripheral surface or recesses radially outward from the inner peripheral surface.
The propeller shaft according to any one of claims 1 to 3. The modules of the first and third spline teeth and the modules of the second and fourth spline teeth are the same.
The propeller shaft according to any one of claims 1 to 4.

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