JPH0348378B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a transmission device for a two-wheeled motor vehicle that has improved primary conduction for transmitting rotation from a clutch shaft to a counter shaft of a speed change gear mechanism.

The basic arrangement of the power transmission system of a motorcycle is that the crankshaft, the countershaft and output shaft of the transmission gear mechanism are mounted in parallel, and the drive gear on the crankshaft and the driven gear on the countershaft. Set the gears to the specified reduction ratio and engage them. The clutch is interposed between the crankshaft and the drive gear, or between the driven gear and the countershaft. In this case, since the reduction ratio from the clutch shaft to the counter shaft is required to be 1/3 or less, the diameter of the driven gear will inevitably become large, and due to the relationship between rotational speed, meshing frequency, unique vibration characteristics, etc. Conditions are conducive to the generation of noise. To prevent this, set a special shape,
Moreover, careful selection of materials and high-precision manufacturing were required.
This inevitably resulted in an increase in costs.

In order to solve the above-mentioned problems, the present invention provides a transmission device for a two-wheeled motor vehicle in which the diameter of the driven gear is set as small as possible, and the primary transmission system is improved so that the condition is such that it is difficult to generate whining noise. It is something that provides.

An embodiment of the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows an embodiment of the present invention, in which a clutch shaft 1 to which power is transmitted from the engine of a motorcycle, a counter shaft 2 and an output shaft 3 are arranged side by side so as to have a common surface. . A drive sprocket gear 4 is fixed to one end of the clutch shaft. The output shaft 3 extends in the direction of the clutch mechanism 9, which will be described later, to form an extension 12.
An idle shaft 13 is rotatably mounted on the shaft. A driven sprocket gear 5 and a drive gear 7 are integrally molded onto this idle shaft 13. Further, a chain 6 is suspended between the drive sprocket gear 4 and the driven sprocket gear 5. The drive gear 7 meshes with a driven gear 8 rotatably supported on the counter shaft 2. The driven gear 8 and the counter shaft 2 are coupled via a clutch mechanism 9.

A primary gear group 10 is pivotally supported on the counter shaft 2, and a secondary gear group 11 corresponding to the primary gear group 10 is pivotally supported on the output shaft 3.
The gears are changed by selecting meshes of 0 and 11. In other words, these gear groups 10 and 11 constitute a constantly meshing multi-stage gear transmission mechanism 14, and power is extracted from the output shaft 3 via the rear wheel drive sprocket 15.

With the above configuration, the crankshaft 1 is rotated by the engine drive of the motorcycle, and the rotation of the crankshaft 1 is controlled by the drive sprocket gear 4, the driven sprocket gear 5, the drive gear 7, and the driven gear 8. is transmitted to the counter shaft 2 via. The reduction ratio of this primary transmission is given by R.r, where R is the gear ratio of both sprocket gears 4 and 5, and r is a gear ratio of both gears 7 and 8. To make the reduction ratio 1/3, if R=1/1.5, then r=1/2.
Therefore, the diameter of the driven gear 8 can be set small, and the diameter of the driven gear 8 can be reduced to approximately 2/3 compared to a conventional driven gear of direct primary transmission.

Note that this invention provides a clutch mechanism that is connected to the crankshaft 1.
A similar structure can be provided in which the clutch shaft 1, the counter shaft 2, and the output shaft 3 are arranged in an L-shape. In the latter case, the chain is suspended on the driven sprocket gear through the outside of the countershaft.

The chain may be not only a commonly used ordinary chain but also a silent chain. Also, a belt can be used instead of a chain. In this case, a drive pulley and a driven pulley are used instead of a drive sprocket gear and a driven sprocket gear. A non-slip timing belt can also be used.

As described above, in the power transmission system for a motorcycle according to the present invention, in which a crankshaft, a countershaft, and an output shaft are arranged in parallel, an extension part is integrally molded on the output shaft, and an idle shaft is attached to the extension part. This system employs a two-stage reduction mechanism in which the rotation of the crankshaft is transmitted over the countershaft to the idle shaft using a chain or belt, and then transmitted to the countershaft. The driven gear can be set to a small size, and therefore, conditions for generating whining noise related to rotational speed, meshing frequency, and unique frequency can be largely avoided, and the problem of primary conduction can be solved. Moreover, since this two-stage reduction mechanism uses an extension of the output shaft, there is no need to add another shaft, and there is no need to increase the size of the transmission case. Alternatively, it is unique in that it can prevent whining noise without requiring special high precision, and improves the function and quality of primary conduction without increasing costs.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view showing the main parts of a two-wheeled motor vehicle transmission device showing one embodiment of the present invention, and FIG. 2 is a layout diagram of the same gear. 1... Crankshaft, 2... Counter shaft, 3...
Output shaft, 4... Drive sprocket gear, 5...
...Driven sprocket gear, 6...Chain, 7
...Drive gear, 8...Driven gear, 9...
Clutch mechanism. 12...Extension portion, 13...Idle shaft, 14...Constantly meshing multi-stage gear transmission mechanism, 1
5...Rear wheel drive sprocket.

Claims (1)

[Claims] 1 A crankshaft, a countershaft, and an output shaft are arranged in parallel, a clutch is interposed between the crankshaft and the countershaft to transmit rotation, and a constantly meshing multistage gear is provided between the countershaft and the output shaft. In a transmission device for a two-wheeled motor vehicle, which is equipped with a speed change mechanism and extracts power from the output shaft, the output shaft is extended toward the clutch to form an extension part, and a drive gear and an integrated part are provided in the extension part. The idle shaft is rotatably mounted, and the rotation of the crankshaft is transmitted to the idle shaft via a chain or belt, and the drive gear and the driven gear on the countershaft are engaged, and the crankshaft is rotated. A transmission device for a two-wheeled motor vehicle, characterized in that the primary transmission from the to the counter shaft is configured to obtain a required reduction ratio by two-stage reduction.