JP2001280366A - Gear shift mechanism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent coming-off of a gear and ensure the strength of a spline simultaneously. SOLUTION: A gear shift mechanism has a sleeve 6 which rotates integrally with a rotary shaft and in which an inner spline 8 is formed and a shift gear 1 in which an outer spline 9 spline-fitted in the inner spline 5 due to the displacement of the sleeve 6 in the axial direction when gear is shifted is formed. A tooth bar shape of the outer spline 9 in a meshing region of the outer spline 9 meshing with the inner spline 8 has a reverse tapered shape constituted by a plurality of taper angles. Moreover, a tooth bar shape of the inner spline 8 in a meshing region of the inner spline 8 meshing with the outer spline 9 has a reverse tapered shape constituted by a plurality of taper angles.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure for preventing a gear from slipping out of a gear transmission mechanism.

[0002]

2. Description of the Related Art Generally, a manual transmission (M
In T), a gear transmission mechanism including a synchronization mechanism is mounted. FIG. 5 is an explanatory diagram of a meshing state in a conventional gear transmission mechanism. Sleeve 1 that is part of the synchronization mechanism
An inner spline 18 is formed on the inner peripheral surface of the nozzle 6. On the other hand, an outer spline 19 is provided on the transmission gear 11 side. The tooth trace shape of the splines 18 and 19 in the region where they mesh with each other is a “reverse taper shape” in which the tooth thickness gradually decreases from the chamfer side to the heel side at a taper angle θ (the angle between the tooth trace and the axis). have. Thus, even if an external force F is applied in the direction in which the spline extends due to an impact during off-road travel, the meshed reverse tapered tooth trace can be formed on the sleeve 1.
Since the displacement of the shaft 6 in the axial direction is restricted, it is possible to prevent the gear from slipping out.

[0003]

In order to increase the force for preventing gear disengagement, it is necessary to increase the above-mentioned taper angle θ to make the reverse taper of the tooth trace of the splines 18 and 19 tight. However, if the taper angle θ is too large, the tooth thickness on the heel side of the splines 18 and 19 becomes extremely small, so that the strength of the splines 18 and 19 may be reduced.

The present invention has been made in view of such circumstances, and an object of the present invention is to achieve both prevention of gear slippage and securing of spline strength.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention relates to a gear transmission mechanism, in which a sleeve having an inner spline formed therein while rotating integrally with a rotating shaft is provided. The transmission gear includes an inner spline and an outer spline that is spline-fitted by axial displacement. here,
In a meshing region of the outer spline that meshes with the inner spline, the tooth trace shape of the outer spline has an inverted taper shape formed by a plurality of taper angles. Also,
In the meshing region of the inner spline that meshes with the outer spline, the tooth trace shape of the inner spline has an inverted taper shape formed by a plurality of taper angles.

Here, in the above configuration, the taper angle on the heel side is preferably smaller than the taper angle on the chamfer side.

[0007]

FIG. 1 is a schematic sectional view of a gear transmission according to the present embodiment. This gear transmission mechanism
Transmission gears 1 and 2 arranged on the left and right sides in the axial direction of the rotating shaft 4
And a synchro mechanism 3 interposed between the transmission gears 1 and 2. As is well known, the synchronization mechanism 3
It has a hub 5 having an outer spline formed on the outer peripheral surface, a sleeve 6 having an inner spline 8 formed on the inner peripheral surface, and a pair of rings 7. The sleeve 6 is spline-fitted to a hub 5 fixedly attached to the rotating shaft 4, and rotates integrally with the rotating shaft 4. The left and right transmission gears 1 and 2 are rotatably mounted on the rotating shaft 4 and have an outer spline 9 that can be fitted to the inner spline 8 on the sleeve 6 side. When the sleeve 6 is shifted to the left or right in the axial direction during the speed change, the sleeve 6 presses the ring 7, so that the tapered surface formed on the inner periphery of the ring 7 and the speed change gear 1 (or the speed change gear) A frictional force is generated between the cone surface and 2). When the sleeve 6 and the transmission gear 1 (2) are eventually synchronized with the increase in the frictional force, the sleeve 6 further shifts, and the inner spline 8 on the sleeve 6 side becomes the outer spline 9 on the transmission gear 1 (2) side. Mates with As a result, the driving force of the transmission gear 1 (2) is transmitted to the rotating shaft 4 from the transmission gear 1 (2) fitted with the spline.

FIG. 2 is an explanatory diagram of the tooth trace shape of the inner spline 8 in the meshing region. Inner spline 8
Have a uniform tooth thickness inside. However, the tooth trace shape in the meshing region L adjacent to the chamfer portion 10 having a sharp tip has a two-stage inverted tapered shape constituted by two different taper angles θ1 and θ2 by cutting. Here, the meshing region L of the inner spline 8 is a portion that meshes with the outer spline 9 on the side of the transmission gears 1 and 2, as shown in FIG. The engagement region L of the inner spline 8 is divided into a first reverse taper region L1 and a second reverse taper region L2 from the chamfer portion 10 toward the heel side. First reverse tapered region L1
The tooth thickness of the inner spline 8 gradually decreases from the tooth thickness of the chamfer portion 10 toward the heel side at a taper angle θ1. Then, the first reverse tapered region L
When reaching the second reverse taper region L2 on the heel side of 1, the tooth thickness gradually narrows toward the heel side at a taper angle θ2 smaller than the taper angle θ1. That is, in the meshing region L, the reverse taper formed in the tooth trace of the inner spline 8 has a taper on the heel side which is gentler than the chamfer side on which the tight taper is formed. As an example, the chamfer-side taper angle θ1 is set to 10 °, and the heel-side taper angle θ2 is set to 2 °. The heel side taper angle θ2 may be 0 °.

FIG. 3 is an explanatory view of the tooth trace shape of the outer spline 9 in the meshing area. The outer splines 9 on the side of the transmission gears 1 and 2 are formed into the same tooth trace shape as the meshing region L of the inner spline 8 by cutting. That is, the tooth trace shape in the meshing region L corresponding to the entire region in the tooth width direction of the outer spline 9 has a two-stage reverse taper shape constituted by two different taper angles θ1 and θ2. In the first reverse taper region L1, the tooth thickness of the outer spline 9 gradually decreases from the tooth thickness of the chamfer portion 10 toward the heel side at a taper angle θ1. Then, when reaching the second reverse taper region L2 on the heel side of the first reverse taper region L1, the tooth thickness is reduced to a taper angle θ2 smaller than the taper angle θ1.
Then, it gradually narrows toward the heel side. That is,
In the meshing region L, the reverse taper formed in the tooth trace of the outer spline 9 is formed such that the taper on the heel side is gentler than the chamfer side on which the tight taper is formed. As an example, similarly to the inner spline 8, the taper angle θ1 on the chamfer side is set to 10 °, and the taper angle θ2 on the heel side is set to 2 °. The heel side taper angle θ2 may be 0 °.

As described above, in the gear transmission according to the present embodiment, the tooth trace shape in the meshing region L between the inner spline 8 and the outer spline 9 is a two-stage having two different taper angles θ1 and θ2. Has an inverted tapered shape. And, the taper angle θ on the chamfer side
1 is larger than the taper angle θ2 on the heel side. Therefore, the sleeve 6 engaged with the transmission gears 1 and 2
Is applied (see FIG. 4), the effect of preventing such displacement is increased by increasing the taper angle θ1 on the chamfer side. Therefore, it is possible to effectively prevent the gear from being lost in the gear transmission mechanism as compared with the related art. At the same time, since the taper angle θ2 on the heel side is smaller than the taper angle θ1 on the chamfer side, it is possible to prevent the heel portion of the splines 8 and 9 from being excessively thin. As a result, there is an effect that a decrease in strength in the engagement region L of the splines 8 and 9 can be effectively prevented.

In the above-described embodiment, the case where the synchronization mechanism is used as the switching mechanism of the transmission gear has been described. However, the present invention is not limited to this, and can naturally be applied to the case where a simple switching mechanism (for example, a dock clutch) having no synchronization function is used.

[0012]

As described above, according to the present invention, on the chamfer side in the meshing region of the spline, the taper angle of the tooth trace can be increased to effectively prevent the sleeve from being displaced due to an impact or the like. At the same time, the taper angle of the tooth trace is reduced on the heel side to prevent the tooth thickness of the spline from becoming excessively narrow. As a result, it is possible to achieve both prevention of gear slippage and securing of spline strength.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a gear transmission mechanism.

FIG. 2 is an explanatory diagram of a chamfer shape of an inner spline.

FIG. 3 is an explanatory view of a chamfer shape of an outer spline.

FIG. 4 is an explanatory view of a meshing state of an inner spline and an outer spline.

FIG. 5 is an explanatory view of a conventional spline fitting.

[Explanation of symbols]

 1, 2, 11 transmission gear, 3 synchro mechanism, 4 rotating shaft, 5 hub, 6, 16 sleeve, 7 ring, 8, 18 inner spline, 9, 19 outer spline, 10 chamfer part

Claims (2)

[Claims] 1. A gear transmission mechanism, comprising: a sleeve that rotates integrally with a rotating shaft and has an inner spline formed therein;
A transmission gear having an outer spline that is spline-fitted with the inner spline; and The inner spline meshes with the outer spline, and the inner spline has a reverse tapered shape formed by a plurality of taper angles. Gear transmission mechanism. 2. The heel-side taper angle is smaller than the chamfer-side taper angle.
2. The gear transmission mechanism according to claim 1.