JPS6216531Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to an improvement in the cooling structure of a power transmission mechanism consisting of a drive belt, etc., which is often used in motorcycles.

Prior art and its problems In a motorcycle, a stepless motor vehicle is equipped with a drive pulley connected to the engine, and a driven pulley that is driven by the rotation of the drive pulley via a drive belt mainly made of rubber, for example. It has a variable speed type power transmission mechanism, and the entire power transmission mechanism is covered with a transmission case to isolate it from the outside.

In this way, if the power transmission mechanism is isolated from the outside by the transmission case, the frictional heat generated between each pulley and the drive belt as the pulleys rotate is transmitted through the air inside the transmission case. Heat is absorbed into the case wall. On the other hand, within this transmission case, air flows as each pulley rotates, but the main flow of air in this case tends to flow radially in the tangential direction around the entire circumference of each pulley. In addition, the airflow collides with each other and tends to stagnate in the approximate middle part between the two pulleys, and is also disturbed by the running of the drive belt that is wound between the two pulleys, causing the airflow to deteriorate throughout the entire area inside the transmission case. There is a problem that the circulation is not carried out smoothly. In particular, as described in Japanese Utility Model Application Publication No. 52-29376, a fibrous material (sound absorbing material 8) is attached to the inner surface of the transmission case (external gear box 6) to increase only the surface area of the transmission case. This method not only obstructs the flow of air through both pulleys, but also hinders the movement of the drive belt itself, and cannot be applied to the drive unit of a motorcycle.

Means for Solving the Problems In order to solve these problems, the present invention provides a driving pulley 11 connected to the engine 2;
The drive belt 1 is rotated by the rotation of the drive pulley 11.
In a motorcycle equipped with a transmission case 5 that covers a power transmission mechanism consisting of a driven pulley 13 driven through a driven pulley 13 and a driven pulley 13 driven through a driven pulley 13 from the outside, It is characterized by providing heat absorption fins 5b, . The heat-absorbing fins 5b, . The purpose is to provide a cooling structure for a power transmission mechanism.

Operation When the drive pulley 11 and the driven pulley 13 rotate, a radial air flow is generated around each pulley 11, 13 in a direction substantially along the tangential direction over the entire circumference thereof.

These radial air flows are caused by heat absorption fins 5
b, . . . are rectified in directions substantially along different running directions on the upper and lower sides of the drive belt 14, respectively, and flow smoothly as a circulating flow throughout the entire area inside the transmission case 5, so that as the pulleys 11 and 13 rotate, Each pulley 11, 13 and drive belt 1
Frictional heat generated between the transmission case 5 and the transmission case 5 is efficiently transmitted through the air flow to the transmission case 5 having the heat absorption fins 5b, . . . , and is radiated from the transmission case 5 into the atmosphere.

Embodiment Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a schematic side view of a motorcycle to which the present invention is applied. An engine 2 is mounted below the approximate center of a vehicle body 1, and a carburetor 3 and an air cleaner 4 are respectively disposed behind the engine 2. A transmission case 5 made of a material with good thermal conductivity is disposed on the left side of the vehicle body 1 further below the mounting position of the engine 2. and,
A power transmission mechanism for transmitting the rotation of the engine 2 to the rear wheels 7 at a variable speed is housed inside the transmission case 5 and is isolated from the outside by the transmission case 5 .

As shown in FIG. 2, the above power transmission mechanism has a drive pulley 11 on the left end of the crankshaft 10 of the engine 2, which has a centrifugal variable pitch structure and uses the crankshaft 10 as its axis of rotation.
However, at substantially intermediate positions of the driven shaft 12 that transmits rotation to the rear wheel 7, driven pulleys 13 having a variable pitch structure with the driven shaft 12 as the axis of rotation are provided, and these pulleys A drive belt 14 having a V-belt structure mainly made of rubber is wound between 11 and 13, and transmits the rotation of the engine 2 to the driven shaft 12. Reduction gear 15 provided in
16 from the final shaft 17 to the rear wheel 7
The rotation is transmitted to the

As shown in FIG. 3, heat absorption fins 5b, . drive belt 1
These heat absorption fins 5b, . . . extend from the vicinity of the crankshaft 10 to the vicinity of the driven shaft 12 as shown in FIG. are extended to each. Note that at least one heat absorption fin 5b may be provided.
Further, on the outer surface 5c of the transmission case 5, which is the surface in contact with the surrounding atmosphere, heat radiation fins 5d, . , . . . to enhance the radiation effect of the collected heat, but these radiation fins 5d, . . . are not essential.

Next, the operation according to this embodiment will be explained.

When the driving pulley 11 and the driven pulley 13 rotate counterclockwise with respect to the arrow direction A in FIG. At the same time, a radial air flow is generated around each pulley 11, 13 that radiates counterclockwise in a direction substantially along the tangential direction over the entire circumference thereof.

These counterclockwise radial air flows collide with the heat absorption fins 5b, ... while taking away the frictional heat, etc., and flow in a direction substantially along the surface of the heat absorption fins 5b, .... The frictional heat, etc. is transmitted to the transmission case 5 having heat fins 5b, .

At this time, the air flow is
b,... from the driving pulley 11 side to the driven pulley 13 side are the lower parts of the transmission case 5, that is, the lower heat absorption fins 5b,... in the part corresponding to rightward running of the drive belt 14. It flows approximately along the extension direction, and in the opposite direction, the transmission case 5
In the upper part of the drive belt 14, that is, in the part corresponding to the left running direction of the drive belt 14, the driven pulley 1 runs approximately along the surface of the upper heat absorption fins 5b, .
Now it flows from the 3 side to the drive pulley 11 side,
In other words, due to the rectifying action of the heat absorption fins 5b, the air flow inside the transmission case 5 becomes a counterclockwise circulating air flow throughout the entire inside of the transmission case 5 as a whole.

This circulating air flow contacts almost the entire inner surface of the transmission case 5 having the heat absorption fins 5b, . Pulley 11,1
Frictional heat and the like generated between the drive belt 3 and the drive belt 14 is efficiently transmitted to the transmission case 5, and is radiated from the transmission case 5 into the atmosphere.

Effects of the Invention As explained above, the cooling structure for the transmission mechanism of a motorcycle according to the present invention consists of a drive pulley connected to the engine and a driven pulley that is driven via a drive belt by the rotation of the drive pulley. In a motorcycle equipped with a transmission case that covers the power transmission mechanism so as to isolate it from the outside, the inner surface of the transmission case on the side opposite to the rotating surfaces of the two pulleys is provided along a direction that substantially coincides with the running direction of the drive belt. The present invention is characterized in that heat absorption fins are provided that extend along the length of the drive belt, so that the inner surface area of the transmission case can be increased, and the heat absorption fins can rectify the air in the transmission case in accordance with the running direction of the drive belt. As a result, the heat can be circulated smoothly over substantially the entire area within the transmission case, and the heat generated within the transmission case can be efficiently exchanged with the transmission case.

[Brief explanation of the drawing]

Fig. 1 is a side view showing an embodiment of a motorcycle to which the present invention is applied, Fig. 2 is a horizontal sectional view of the power transmission mechanism of the motorcycle shown in Fig. 1, and Fig. 3 is a transmission shown in Fig. 2. FIG. 3 is an enlarged vertical cross-sectional view of the main part of the case. 2...Engine, 5...Transmission case, 5a...
Inner surface of transmission case, 5b... Heat absorption fin, 11...
... Drive pulley, 13... Driven pulley, 14... Drive belt.

Claims (1)

[Scope of utility model registration request] A motorcycle comprising a transmission case that covers a power transmission mechanism consisting of a drive pulley connected to an engine and a driven pulley driven via a drive belt by the rotation of the drive pulley from the outside. A cooling structure for a power transmission mechanism of a motorcycle, characterized in that heat absorption fins are provided on the inner surface of the case on the side facing the rotating surfaces of the two pulleys, the heat absorption fins extending in a direction substantially coinciding with the running direction of the drive belt. .