JPS6133316Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a change device used in a transmission mechanism of a motorcycle or the like.

Generally, a change device incorporated into a transmission mechanism of a motorcycle or the like has a structure as shown in FIG.

That is, a shift drum 3 having a cam groove 2 formed on its outer periphery is rotatably mounted inside the case 1 via a bearing 4, and a guide shaft 5 parallel to the shift drum 3 is installed inside the case 1. A shift fork 6 is slidably fitted into the guide shaft 5, the base end of the shift fork 6 is engaged with the groove 2 of the shift drum 3, and the distal end is connected to the main shaft on the transmission side. He is trying to engage with the fitted sleeve 7.

By rotating the shift drum 3, the shift fork 6 engaged with the groove 2 of the shift drum 3 slides along the guide shaft 5, thereby changing the meshing state of the gear train arranged in the transmission. , I'm trying to shift gears.

However, in such a conventional structure, when the shift fork 6 slides along the guide shaft 5, the shift fork 6 may fall or become distorted, causing the shift fork 6 to be pulled by the sliding movement of the shift fork 6. There may be a problem.

The present invention has been developed in view of the above-mentioned disadvantages, and its purpose is to provide a change device that can shift gears more smoothly than before.

In order to achieve such an object, the present invention supports a guide shaft on the case side, into which the shift fork is inserted and guides the sliding movement of the shift fork in accordance with the rotation of the shift drum, and also supports a guide shaft at the end of the guide shaft of this support part. The gist is that an elastic member is interposed between the part and the case side to hold the guide shaft in a floating state in the axial direction.

An example of implementing the present invention will be described in detail below with reference to FIG.

Inside the case 11 of the change device 10, there is a shift drum 1 having a meandering engagement groove 12 formed on its outer circumference.
3 is rotatably mounted on bearings 14, 14, respectively. Further, support portions 11b, 11b are formed in the left and right side walls of the case 11, and these holes 11a, 11b are provided with holes 11a, 11a that open inward.
The shift fork 16 was inserted into the hole a, and the left and right ends 15a, 15a of the guide shaft 15 were inserted.

Then, an end surface 15b of the guide shaft 15 and an end surface 11c of the hole 11a facing the end surface 15b.
A space S is formed between the guide shaft 15 and the guide shaft 15. A hole 18 is formed in the end 15a of the guide shaft 15 in the axial direction, and the hole 18 opens in the end surface 15b. And this hole 1
A coil spring 19, which is an elastic member whose tip end comes into contact with the end surface 11c of the hole 11a, is compressed inside the coil spring 8.

Further, the base of the shift fork 16 that is slidably fitted into the guide shaft 15 is formed with an engaging portion 16a that engages with the groove 12 of the shift drum 13, and has a bifurcated tip (not shown in the figure). (They overlap, so they do not form a bifurcated shape), but the low gear,
Shaft 2 fitted with each gear such as the second gear
It is engaged with the sleeve 17 fitted on the sleeve 0.

In the above, when the shift drum 13 is rotated via the shift change mechanism, the shift fork 16 is engaged with the groove 12 of the shift drum 13, so the shift fork 16 is rotated by the guide shaft 1.
5 to change the meshing state of each gear on the transmission side to change gears.

When the shift fork 16 slides along the guide shaft 15, even if the shift fork 16 falls or is twisted, the guide shaft 15 is prevented from floating in the axial direction by the coil springs 19, 19. In this state, the shift fork 16 can move from side to side integrally with the guide shaft 15. Particularly, the shift fork 16 gets stuck due to falling or twisting, which occurs at the initial stage of sliding, and once sliding starts, the shifting continues smoothly. Therefore, the change device of the present invention, which allows the shift fork 16 to start moving smoothly, also allows the subsequent sliding movement to occur extremely smoothly.

As is clear from the above explanation, according to the present invention, the guide shaft on which the shift fork slides is supported in a floating state in the axial direction via an elastic member such as a spring between the end of the guide shaft and the case side. Therefore, the shift fork does not get stuck during the initial movement, and the operability of the shift operation can be improved, and this improvement in operability can be achieved by a simple mechanism, which provides many advantages.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention and a conventional example. Fig. 1 is a front view of a part of the conventional change device with a new surface, and Fig. 2 is a front view of a part of the change device according to the present invention. It is a front view taken as a cross section. In addition, in the drawing, 1 and 11 are cases, 2 and 12 are grooves,
3 and 13 are shift drums, 5 and 15 are guide shafts, 6 and 16 are shift forks, and 19 is an elastic member.

Claims (1)

[Scope of utility model registration request] A shift fork, one end of which engages with a groove formed on the outer periphery of the shift drum and the other end of which engages with a transmission side, is slidably fitted into a guide shaft supported on a case side. A change device characterized in that an elastic member is interposed between the end of the guide shaft and the case side to keep the guide shaft in a floating state in the axial direction.