JPS58203252A - Speed change gear for motorcycle - Google Patents

Abstract

PURPOSE:To make the structure of a speed change gear to a compact size and to balance the right and left weights by supporting an intermediate shaft on an upper crank case and a crankshaft and a main shaft on a joining surface portion, respectively. CONSTITUTION:An intermediate shaft 4 is supported by an upper crank case 12, and a countershaft 7 is supported by a lower crank case 13. A crankshaft 1, a main shaft 6 and an output shaft 14 are supported by a joining surface portion of the upper and lower crank cases 12, 13. As the intermediate shaft 4, the crankshaft 1 and the main shaft 6 are thus supported, the distance between the crankshaft and the main shaft is shortened so as to shorten the longitudinal length of an engine, which results in reducing a speed change gear to a compact size. The intermediate shaft 4 and a member mounted on the shaft 4 for transmitting power to a clutch can balance the right and left weights.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a motorcycle transmission suitable for use in a motorcycle equipped with an intermediate shaft, particularly a large motorcycle equipped with a large displacement engine.

In general, in a motorcycle, the space for mounting equipment such as an engine is extremely limited, and especially when a large displacement engine is mounted, it is necessary to make the engine, transmission, etc. compact. Furthermore, since the engine and transmission are extremely heavy, it is necessary to balance the left and right weights well when mounted on a vehicle.

Furthermore, in order to make the left and right bank angles as equal as possible and to improve the appearance, it is necessary to make the engine and transmission as symmetrical as possible, and to take serviceability into consideration during busy periods. However, conventional transmission configurations have not been able to simultaneously satisfy all of these requirements for motorcycle engines and transmissions.

FIGS. 1 and 2 are explanatory diagrams of the configuration of a conventional transmission, both of which are coupled to a double overhead camshaft type engine. In FIG. 1, 1 is a crankshaft, 2 is a camshaft, and 3 is a timing chain for timing the crankshaft 1 and camshaft 2. An intermediate shaft 4 is connected to the crankshaft 1 by a chain 5, and transmits 10 revolutions of the crankshaft to a transmission 8, which will be described later. Reference numeral 6 indicates a main shaft, and reference numeral 7 indicates a sub-shaft, which together with gear trains provided on both shafts constitute a transmission 8.

The rotation of the intermediate shaft 4 is transmitted to the gear on the secondary shaft T via the gear on the main shaft 6, and the gear ratio is changed by selecting an appropriate blade surface gear train.

Reference numeral 9 denotes a chain wound between the rear wheel (not shown) and the subshaft 7. In addition, 10 in the figure indicates the joint surface of the crank case, and this crank case is connected to the transmission 8 and the intermediate shaft 4.
Also serves as 0 case. Then, crankshaft 1. Main shaft 6
The subshaft 7 and the intermediate shaft 4 are respectively supported by the joint surface and the lower crankcase.

In the transmission configured as described above, the intermediate shaft 4 is rotatably supported by the lower crank case, and the intermediate shaft 4 and the crankshaft 1 are connected by a chain 5. When dividing the timing chain 3 and camshaft 2, it is also necessary to disassemble the timing chain 3 and camshaft 2.
There was a problem that serviceability was poor and work efficiency was extremely reduced.

In the conventional transmission shown in FIG. 2, there is no intermediate shaft, and the rotation of the crankshaft 1 is directly controlled by the chain wheel 11.
It is transmitted to the gear provided in the. In FIG. 2, the same parts as in FIG. 1 are given the same reference numerals. When the intermediate shaft is omitted in this way, the rotation of the crankshaft 1 is transmitted to the clutch coaxially with the main shaft 6, so the position of the clutch in the left-right direction (vehicle width direction) is determined by the chain 11 being wound around. It is determined by the position of the sprocket on the crankshaft 1. Therefore, the clutch will protrude in either the left or right direction, or conversely, the clutch (011 will not protrude, but instead the clutch Oi!1I116 on the same axis will protrude).

As a result, there have been problems in that not only is the left and right appearance of the engine and transmission as a whole unbalanced, there is also a large difference in left and right bank angles, and the left and right weight balance is also disrupted.

As described above, conventional transmissions have been unable to simultaneously satisfy all of the various requirements required for automatic two-shaft transmissions.

This invention was developed in view of the problems with conventional transmissions, and by supporting the intermediate shaft in the upper crank case and supporting the crankshaft and main shaft in the joint surface, the invention is made compact as a whole. The object of the present invention is to provide a power transmission for a motorcycle, which has a good balance between left and right weights, has equal left and right bank angles, and has a well-balanced appearance, and also has good serviceability during maintenance.

The present invention will be described in detail below based on the drawings.

FIG. 3 is a side view showing the structure of the transmission according to the present invention, and FIG. 4 is a plan view thereof. In these figures, the same parts as in FIGS. 1 and 2 are given the same reference numerals. As can be clearly seen in FIG.
It is pivoted on.

Also, crankshaft 1. The main shaft 6 and the output shaft 14 are pivotally supported by the joint surfaces of the upper and lower crankcases 12,13. Further, as shown in FIG. 4, a generator 15 and an ignition device 16 are provided at both ends of the crankshaft 10. The rotation of the crankshaft 1 is transmitted to the sprocket 18 of the intermediate shaft 4 by a chain 5 wound around a sprocket 17 provided approximately at the center of the crankshaft 1. This intermediate shaft 4
A one-way clutch 19 is provided coaxially with the starter motor 20, and the rotation of the starter motor 20 is controlled by an intermediate gear 21 and a gear 22 on the intermediate shaft 4.
is transmitted to the sprocket 18 via.

23 is a clutch provided coaxially with the ball shaft 6, and the clutch drum 24, which is written in Japanese, has an intermediate @4
The rotation is transmitted to the gear 25 fixed to the. The rotation transmitted to the main shaft 6 via the clutch 23 is changed in speed by a train 26 provided on the main shaft 6 and the sub-shaft T, and is transmitted to the output Wh14. This rotation of the output shaft 14 is transmitted to drive wheels (not shown) via the bevel gear 2 and the propeller shaft 28.

As described above, according to the present invention, the middle MJ shaft is supported by the upper crank case, and the crankshaft and main shaft are each supported by the joint surface, so that the crankshaft and main shaft are pinched, and as a result, the front and back direction of the engine is It is shorter in length and can be made more compact as a whole. In addition, since the intermediate shaft can be set up at any position on this shaft, it is possible to install a member that affects the clutch at any position on this shaft, so the leftward position of the clutch can be freely determined, and the clutch and speed change Not only does the weight balance of the machine, bevel gears, etc. become easier, but by making the E stones almost symmetrical in a cedar shape, the left and right bank angles can be made equal and the appearance can be improved. Furthermore, since the intermediate shaft is supported by the upper crank case, when the joint surface is separated for maintenance, the intermediate shaft remains on the upper crank case side along with the crankshaft, eliminating the need to disassemble the timing gear and camshaft. , thus improving serviceability during maintenance.

[Brief explanation of drawings]

Figures 1 and 2 are explanatory diagrams of the configuration of a conventional transmission;
4 are a side view and a plan view showing the structure of a transmission according to the present invention. 1... threat crankshaft, 4'11... intermediate shaft, 5...
・・Chain, 6 fists・・・Main shaft, 71・・Secondary shaft, 8・
...Transmission, 10...Joint surface, 12...e@upper crank case, 13...Lower crank case, 2
6...#Gear train. Patent applicant: Yamaha Corporation, + Machinery Co., Ltd. agent: Kazuhata Yamakawa (1 person)

Claims (1)

[Claims] A crankshaft, an intermediate shaft connected to the crankshaft by a chain, a transmission that changes the rotation of this intermediate shaft using a gear train installed on the main shaft and subshaft, and a transmission system divided into upper and lower halves that houses these. A transmission for a motorcycle, comprising: a crank case; the intermediate shaft is supported by the upper crank case, and the crankshaft and the main shaft are each supported by a joint surface.