JPS6131915Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a power transmission device using a chain transmission for a two-wheeled vehicle.

Generally, in a chain transmission power transmission device for a motorcycle, a transmission chain is suspended between a drive sprocket that is linked to the engine and a driven sprocket that is connected to the rear wheel at the rear end of the rear fork, and the transmission chain is suspended between a drive sprocket that is linked to the engine and a driven sprocket that is connected to the rear wheel at the rear end of the rear fork. However, in this case, the center of rotation of the drive sprocket and the center of swing of the rear fork are separated from each other in the longitudinal direction of the vehicle body frame. The up and down swing of the rear fork causes fluctuations in the tension acting on the transmission chain, causing problems such as slack in the transmission chain, which may cause it to come loose and reduce power transmission efficiency. Therefore, as a means to eliminate such a problem, when the two-wheeled vehicle is in a standard stopped state, as shown in FIG. If the rotation center C of the driven sprocket 2 is made to coincide with the rotation center C of the driven sprocket 2, and the rear fork 4 is made to swing up and down by 1/2 of the total swing stroke H about the straight line L-L, the tension in the transmission chain 3 can be reduced. It is possible to minimize fluctuations, but generally in motorcycles,
From the viewpoint of the layout of each part, its characteristics, functions, manufacturing costs, or appearance, even if the rear fork 4 is lowered to its lowest position as shown in FIG. In most cases, it is designed to be located below C. However, if you do this, the second
As is clear from the figure, an arc of radius ι1 drawn by the rotation center C of the driven sprocket 2, that is, the rear wheel W, centering on the rotation center A of the drive sprocket 1, and an arc of radius ι1 drawn by the rotation center C of the driven sprocket 2, that is, the rear wheel W, centering on the rotation center A of the drive sprocket ₁ , and the rear wheel arc around the rotation center B of the rear fork 4. A longitudinal deviation occurs between the rotation center C of W and the circular arc of radius _ι2 , and when the rear wheel W moves upward, the driven sprocket 2, that is, the rotation center C of the rear wheel W, moves in the longitudinal direction. Not only does this cause a large amount of slack in the transmission chain 3, but also by lowering the swing center B of the rear fork 4 as described above, the rear fork 4
The front lower surface of the transmission chain 3 interferes with the transmission chain 3, which not only prevents smooth operation of the transmission chain 3 but also causes the inconvenience of wearing it.

In view of the above, the present invention prevents the transmission chain from sagging and from coming into contact with the rear fork, thereby overcoming the disadvantages of the conventional method, and has high power transmission efficiency and excellent durability. The objective is to provide a power transmission device for two-wheeled vehicles that is lightweight, compact, and easy to maintain.

Hereinafter, one embodiment of the present invention will be described with reference to FIGS. 3 to 5. A drive sprocket 1 that is interlocked with an engine E suspended on a vehicle body frame F, and an axle 5 at the rear of a rear fork 4 that is rotatably mounted An endless transmission chain 3 is suspended between the driven sprockets 2 connected to the mounted rear wheels W, and when the engine E is driven, the drive sprockets 1,
A rear wheel W is driven via a transmission chain 3 and a driven sprocket 2.

The front end of the rear fork 4 is pivotally supported by the vehicle body frame F behind the drive sprocket 1 so as to be able to swing up and down. Therefore, the extension of the straight line LL passing through the rotation center A of the drive sprocket 1 and the swing center B of the rear fork 4 is the direction of the driven sprocket 2, that is, the rear wheel W when the rear fork 4 swings downward. The rotation center A of the drive sprocket 1 passes below the rotation center C.
is set.

Next, the structure of the shaft support of the rear fork 4 will be explained in detail mainly with reference to FIG.
A pivot shaft 6 is horizontally fixed to the pivot shaft 6, and a collar 8 with an elastic bush 7 interposed therebetween is attached to the pivot shaft 6.
A front hollow shaft portion 4' of the rear fork 4 is rotatably supported via a shaft 9. A roller 12 is rotatably supported at the outer end of the pivot shaft 6 that protrudes outward from the vehicle body frame F via a collar 11, and this roller 12 is attached to a nut 13 screwed onto the outer end of the pivot shaft 6. The axial position is regulated by. The roller 12 is constructed by fitting an elastic outer ring 15 around the outer periphery of a roller main body 14, and is located within the vertical swing locus of the transmission chain 3. The outer diameter of the roller 12 is such that the outer peripheral surface of the roller 12 normally forms a gap with the inner surfaces of the transmission chain 3 on the tension side and the slack side, and when the rear fork 4 swings upward, the transmission chain 3
The size is set such that it can engage with the chain 3 and apply appropriate tension to the chain 3.

When the engine E is now driven, its rotational force is transmitted to the rear wheel W via the drive sprocket 1, transmission chain 3, and driven sprocket 2.
The motorcycle can be driven, but in this case, the rear fork 4 moves up and down around the pivot axis 6, that is, the center of swing B, due to the load on the body frame F, the external force acting on the rear wheel W, etc. oscillate. In this case, when the rear fork 4 swings upward and the amount of upward swing increases to such an extent that the amount of slack in the transmission chain 3 cannot be ignored, the transmission chain 3
The lower inner surface of the roller 12 comes into contact with the outer peripheral surface of the roller 12, and when the roller 12 is rotated in the direction of the arrow in FIG. It is possible to absorb the slack of the transmission chain 3 due to this.

As described above, according to the present invention, the vehicle body frame F
The front end of a rear fork 4, on which a rear wheel W is mounted, is supported by a pivot shaft 6 so as to be able to swing up and down, and a driving sprocket 1 driven by the engine E is connected to the rear wheel W in front of the pivot shaft 6. A transmission chain 3 is connected between the driven sprocket 2 and the connected driven sprocket 2.
In a power transmission device for a two-wheeled vehicle that suspends a
A roller 12 facing the swing locus of the transmission chain 3 is rotatably supported at one end of the pivot shaft 6. A gap is formed between them, and when the rear fork 4 swings upward, it is set to engage the transmission chain 3 and apply tension to the chain 3, so that external forces acting on the rear wheel W, etc. When the rear fork 4 swings upward, the outer circumferential surface of the roller 12 engages with the transmission chain 3, and the chain 3 is operated properly under appropriate tension without loosening. Therefore, the output of the engine E can be efficiently transmitted to the rear wheels W, and contact interference with other members due to slack in the transmission chain 3 can be suppressed. Furthermore, during normal running of the motorcycle when the rear fork 4 is not swinging upward, the outer peripheral surface of the roller 12 is in a non-contact state with the transmission chain 3. There is no risk of any reduction in power transmission efficiency between the transmission chains 3 and 3.
Since the contact time between the chain 3 and the roller 12 can be reduced as a whole, in combination with the fact that the roller 12 itself is configured to be rotatable, the wear of the chain 3 and the roller 12 can be reduced as much as possible to improve their durability. You can increase your sexuality. Moreover, the roller 12
Since the outer diameter of the transmission chain 3 can be made shorter than the distance between the inner surfaces of the tension side and the slack side, the roller 12 itself can be constructed to be lightweight and compact. Since the chain 3 itself does not bulge in the vertical direction due to engagement with the rollers 12, the overall length of the transmission chain 3 can be shortened, contributing to the weight reduction of the device, and the transmission chain 3 can be expanded in the vertical direction. The swing space and therefore the occupied space can be made more compact.

Further, the roller 12 is located on the outside of the front end of the rear fork 4 and is configured to be detachable from one end of the shaft 6. It can be attached and detached very easily and quickly without being obstructed by the front end. Therefore, it is easy to replace the worn roller 12 with a new part, adjust the mounting position, etc. It can contribute to improving maintainability. Moreover, since the attachment part of the front end of the rear fork 4 to the pivot shaft 6 does not protrude outward beyond the transmission chain 3, the total width of the attachment part in the left and right direction can be made relatively short, and therefore the pivot shaft of the vehicle can be made relatively short. 6. The peripheral area can be made more compact in the left-right direction, and parts can be arranged in the peripheral area without difficulty.

[Brief explanation of the drawing]

Fig. 1 is a schematic side view showing a standard chain transmission mechanism of a motorcycle, Fig. 2 is a schematic side view showing a conventional transmission mechanism of a motorcycle, and Figs. 3 to 5 show an embodiment of the device of the present invention. 3 is a partial cross-sectional plan view thereof, FIG. 4 is a side view thereof, and FIG. 5 is an enlarged cross-sectional plan view of the rear fork shaft support. E...Engine, F...Vehicle frame, W...
Rear wheel, 1... Drive sprocket, 2... Driven sprocket, 3... Transmission chain, 4... Rear fork, 6... Pivot shaft, 12... Roller.

Claims (1)

[Scope of utility model registration request] The front end of a rear fork 4 on which a rear wheel W is mounted is pivotably supported up and down by a pivot shaft 6 on a vehicle body frame F, and a drive sprocket 1 is positioned in front of this pivot point and driven by an engine E; In a power transmission device for a two-wheeled vehicle in which a transmission chain 3 is suspended between a driven sprocket 2 connected to the rear wheel W, one end of the pivot shaft 6 includes:
A roller 12 located on the outer side of the front end of the rear fork 4 and facing the swing locus of the transmission chain 3 is rotatably and removably supported.
The outer diameter of the roller 12 is such that the outer peripheral surface of the roller 12 normally forms a gap with the inner surface of the transmission chain 3, and when the rear fork 4 swings upward, it engages with the transmission chain 3 and is connected to the transmission chain 3. A power transmission device for two-wheeled vehicles that is configured to apply tension.