JPH0676823B2 - Belt transmission - Google Patents

Description

TECHNICAL FIELD The present invention relates to a belt transmission, and more particularly to a belt transmission cooling structure suitable for a V-belt type automatic continuously variable transmission mounted on a motorcycle.

<Prior Art> A V-belt type automatic continuously variable transmission is generally used as a belt transmission device for a motorcycle or the like. This is a two variable pulley (a drive pulley and a drive pulley) around which a V-belt is wound around a crank shaft extending from a crank case below a cylinder block and an output shaft extending from a transmission case connected to drive wheels. It is connected by an automatic continuously variable transmission composed of a driven pulley) so that the gear ratio can be automatically changed according to the throttle operation of the engine and the running condition of the vehicle.
The V-belt type automatic continuously variable transmission is housed in a belt chamber provided between the crankcase and the transmission case. This belt chamber is generally hermetically sealed in order to prevent rainwater and dust from entering.

Moreover, since such a belt transmission utilizes friction transmission between the V-belt and the pulley, it has a heat-generating portion at the contact portion between the pulley and the V-belt, and the temperature in the belt chamber easily rises. The tendency becomes greater in a compact belt chamber. Therefore, in order to eliminate the possibility that the V-belt deteriorates due to heat generation, the V-belt has good durability but is expensive
It is necessary to take measures such as using a belt.

Further, in order to suppress heat generation as much as possible and extend the life of the V-belt, it is generally performed to effectively and forcibly cool the inside of the belt chamber with cooling air sucked from the outside. As this cooling method, for example, as shown in JP-A-58-126276, a cooling air inlet is provided in the wall portion of the belt chamber, and a suction fan for sucking the cooling air into the belt chamber from the inlet is provided. A drive pulley and a driven pulley provided on the back surface of each are known.

<Problems of the prior art> However, if a suction fan is provided on the driving pulley and the driven pulley to suck cooling air from the outside and forcibly cool the continuously variable transmission, fluid resistance acts on the suction fan. , The load on the engine will increase. Besides,
This load increases as the rotation increases. Above all, if a suction fan is installed on the driven pulley side, a resistance member will be installed on the output part already decelerated by the continuously variable transmission itself, so the output from the crankshaft cannot be consumed only for the drive system. , Driving force is lost to the drive system, which affects fuel efficiency and the like. The impact of this loss is
The smaller the engine, the more significant the problem in the process of pursuing improved power performance.

On the other hand, since the V-belt rotates in one direction in the plane where the V-belt is arranged in the belt chamber, the V-belt also generates a circulating flow in a constant direction in the belt chamber together with the blowing of the suction fan.

However, this circulating flow does not contribute to the cooling of the belt chamber because it circulates only inside the belt disposition plane including the heat generating portion. The belt disposing plane means a plane including the entire belt that is annularly disposed.

Regarding the cooling of the belt chamber, as shown in Japanese Utility Model Laid-Open No. 60-61433, by arranging the ventilation pipes in the front-back direction inside the belt chamber, the surroundings of the ventilation pipes are cooled to achieve room temperature cooling. However, since this structure is an indirect cooling structure and does not directly introduce cooling air into the belt chamber, it cannot improve room temperature cooling of the circulating flow.

Therefore, in the present invention, a cooling fan is provided outside the belt chamber with respect to the belt transmission device, and by utilizing this, cooling air is pressure-fed from the outside to the belt chamber and the continuously variable transmission forcibly and effectively cooled. In addition to increasing the ventilation efficiency in the belt chamber, the cooling air is efficiently introduced to lower the room temperature in the belt chamber, thereby prolonging the life of the belt and providing a cooling structure that can reduce the loss of driving force. A belt transmission is provided.

<Structure of the Invention> In order to solve the above-mentioned problems, the belt transmission device of the present invention has a substantially closed belt chamber and a driving pulley, a driven pulley, and both pulleys housed in the belt chamber in the vehicle traveling direction. In a belt transmission consisting of a belt wound around a cooling fan, a cooling fan is attached to one end of the crankshaft arranged in the vehicle width direction, a drive pulley is attached to the other end across the engine, and a cooling fan is attached to one side of the engine. A fan case accommodating the fan chamber is separately provided on the other side, and the belt chamber and the fan case are connected by an air passage having a hollow portion, and one end of the air passage is connected to the fan case. A high pressure portion formed in the vicinity of the outer peripheral portion of the cooling fan, and the other end is opened in the vicinity of the drive pulley in the belt chamber to cool the belt in the direction across the plane. It is characterized in that exhaust air is discharged and an exhaust passage communicating with the outside air is opened near the driven pulley.

<Operation of the Invention> First, when the cooling fan attached to one end of the crankshaft rotates as the crankshaft rotates, the outside air of a relatively low temperature is sucked into the fan case and becomes cooling air. A part of these is compressed near the wall surface to form a high pressure portion of the suctioned outside air. Since the air outlet of the air passage is opened in this high-pressure portion, the cooling air is pressure-fed into the air passage from the air outlet, and is discharged from the outlet to the vicinity of the drive pulley in the belt chamber in the direction crossing the belt mounting plane. To be done.

The discharged cooling air cools the transmission devices such as the belt and the pulley, and also traverses the circulation flow in the plane in which the belt is arranged. Therefore, this circulation flow is positively diffused to dissipate the heat throughout the belt chamber. , The temperature inside the belt chamber is lowered by the mixed flow.

The cooling air that has undergone heat exchange in this way becomes exhausted air whose temperature has risen, and is exhausted into the atmosphere from the exhaust passage that opens near the driven pulley. As a result, the entire belt chamber is efficiently ventilated.

<Embodiment> FIGS. 1 to 4 show a V-belt type automatic transmission for a motorcycle, which is an embodiment of a belt transmission device according to the present invention.

The left / right, front / rear directions used in the following description are all based on the traveling direction (the X direction shown by the arrow in FIGS. 1 and 2), and the upper / lower directions are the ground contact directions (first The Y direction indicated by the arrow in FIG. 1) is the downward direction. FIG. 1 shows a right side surface of the vehicle body with a part thereof omitted.

A fan case F that covers the engine and the like is provided on the right side surface of the vehicle body. As is apparent from FIG. 2, the fan case F includes an engine E, a crank chamber C continuously provided under the engine E, a generator AC, and a generator AC.
It contains a cooling fan FN that is fixed to the side surface.

A transmission case is provided on the left side surface of the vehicle body. This case is crank chamber C, belt chamber B and mission chamber M.
It is a series of.

Inside the belt chamber B, a V-belt type automatic transmission T is arranged. Although the V-belt type automatic transmission T is known,
To outline this, the V-belt type automatic transmission T is composed of a drive pulley 2 around which a belt 1 is wound, a driven pulley 3 and the like, and each pulley is a die cast product of aluminum with good heat conduction. Paired pulley halves
It consists of 4a / 4b and 5a / 5b.

The drive pulley 2 is attached to the crankshaft 6 extending from the crank chamber C to the belt chamber B, and the pulley half 4a is fixed and the pulley half 4b is axially slidable. A governor 7 is integrally provided on the pulley half body 4b. The cover 7 is a known device that slides the pulley half 4b in the axial direction by the action of the centrifugal weight corresponding to the increase and decrease in the rotation speed of the crankshaft 6.

The driven pulley 3 has a pulley attached to the output shaft 8 extending from the transmission chamber M to the belt chamber B together with the centrifugal clutch 9, with the pulley half 5a as the fixed side and the pulley half 5b.
Is a movable side and can be slid in the axial direction by a spring or the like (not shown).

By the action of the governor 7 corresponding to the increase and decrease in the rotation speed of the crankshaft 6, the movable pulley half body 4b is slid in the axial direction to change the belt radius of the drive pulley 2. Along with this, the belt radius of the driven pulley 3 is also changed, so that continuously variable transmission is automatically realized.

The output thus changed in speed is input from the output shaft 8 to the mission chamber M via the centrifugal clutch 9, where it is finally decelerated to drive the rear wheel W.

The belt chamber B is a closed space formed by a cover 10 that has a built-in V-belt automatic transmission T and is connected to the crank chamber C and the mission chamber M. The cover 10 is composed of inner and outer covers 11 and 12 with respect to the center of the vehicle body.

Cover packings 13 and 14 are provided at the connecting portions of the outer cover 12, the crank chamber C, and the mission chamber M to enhance the hermeticity of the cover 10. This sealing property is required to prevent dust and rainwater from entering the belt chamber B.

The cover packings 13 and 14 and the driving pulley 2 and the driven pulley 3 are narrowed to form a gap, and the crank chamber C
Also, the vicinity of the mission chamber M is set to a low pressure portion of the high temperature air so that the high temperature air is less likely to flow around the drive pulley 2 and the driven pulley 3 and the low temperature air on the outer cover 12 side is made to easily flow toward the low pressure portion. ing.

An exhaust port 16 is opened in the upper part of the driven pulley 3 at the rear part of the upper surface 15 of the cover 10, and an exhaust part (described later) is provided here. Further, there are gaps 17 and 18 between the outer cover 12, and the drive pulley 2 and the clutch 9, respectively, to form air passages.

The fan case F uses the fan cover 20 for the engine E.
It is surrounded and formed by integrally covering up to and connected to the crank chamber C. An opening 21 is formed in a portion of the fan cover 20 corresponding to the cooling fan FN, and a fan case cover 22 is mounted on the opening 21 to cover the opening 21.

The fan case cover 22 has a bowl shape, an outside air suction port 23 is formed at a portion corresponding to the opening 21, and the suction port 23 is provided with a large number of louvers 24 inclined downward.

The louver 24 blocks the intrusion of rainwater and dust and mud that are splashed up by the front wheels. Further, a high pressure portion 27 for the intake outside air is formed in a portion where the blades 25 of the cooling fan FN and the rear wall surface 26 of the fan cover 20 are close to each other.

An air passage 30 is provided between the fan case F and the belt chamber B to connect them. The air passage 30 is formed of a pipe-shaped member, and its hollow portion 31 forms a passage for guiding air. One end of the air passage 30 opens to the high pressure portion 27 of the fan case F to form an air outlet 32 (see FIG. 3).

On the other hand, the other end opens to the upper part of the inner cover 11 to form a discharge port 33 (see FIG. 4).

Further, as shown in FIG. 2, the longitudinal position of the discharge port 33 in the belt chamber B is relatively close to the drive pulley 2 and is arranged at a position close to the crank chamber C so as to cross the belt arranging plane. Further, cooling air is discharged into the belt chamber B. The air passage 30 is supported by a mounting portion extending from the crank chamber C via pushes 34 and 35, and an intermediate portion thereof.
36 is separated from the crank chamber C.

Further, as shown in FIG. 4, the exhaust port 16 is provided with an exhaust passage 40. The exhaust passage 40 is a substantially inverted U-shaped tubular member, one end of which is attached to the exhaust outlet 16 to serve as an inlet 41 that opens into the belt chamber B, and an intermediate portion thereof serves as a curved portion 42 that curves downward.
The tip opening is used as the downward discharge port 43.

The exhaust unit may be formed integrally with the cover 10, and the shape thereof may be simply projected or inclined such that the discharge port faces rearward or downward.

Next, the operation of this embodiment will be described. First, the cooling fan FN
When is rotated in the Z direction (see FIG. 3) as viewed from the arrow, the outside air of relatively low temperature is sucked into the opening 21 from the suction port 23 of the fan case cover 22 and becomes cooling air as shown by the white arrow. , Is radiated in the radial direction of rotation.

At this time, most of the dust and rainwater are blocked by the louver 24. As shown in FIG. 2, most of the sucked cooling air is blown in the direction of arrow a to forcibly cool the engine E.

However, some of these parts are part of the rear wall 26
Is sent in the direction and compressed near the wall surface to form the high-pressure portion 27. However, the air outlet 32 of the air passage 30 is opened here.

Therefore, the cooling air flows from the air outlet 32 to the hollow portion 31 of the air passage 30.
It is pumped in and discharged from the discharge port 33 into the belt chamber B.

At this time, the air passage 30 has the clamp chamber C at both ends thereof.
Since it is separated from the clamp chamber C except for the supporting part of the air conditioner, the atmosphere is always in contact with the periphery of the intermediate part 36, the influence of the engine E is minimized, and the cooling air passing through the air passage 30 is heated. Reduce temperature rise.

As shown in FIG. 2, the mainstream of the cooling air discharged from the discharge port 33 advances straight in the direction of arrow C and crosses the belt disposition plane. At this time, in the belt chamber B, the belt 1 is rotating in one direction within the plane in which it is arranged, so that a circulating flow in a certain direction is generated in the belt chamber B. This circulating flow merely generates heat. Since it merely circulates in the plane in which the belt is disposed including the portion, it does not contribute much to the cooling of the belt chamber B.

However, since the cooling air discharged from the discharge port 33 crosses the belt arrangement plane, the circulating flow is positively diffused and dispersed in the entire belt chamber B, and the temperature in the belt chamber B is increased by the mixed flow. Lower.

Further, in FIG. 2, the cooling wind that has proceeded straight in the direction of arrow C collides with the side surface of the opposing outer cover 12, and the belts such as front and rear and top and bottom including the representative directions in plan view illustrated by arrows N and E are included. It is dispersed in various directions in the room, and further contributes to lowering the temperature in the belt room B.

For example, the cooling air diverted in the direction of the arrow D rides on the rotation of the belt 1, and the ambient temperature in the belt chamber B and the belt 1
While cooling, the belt 1 and the driving pulley 2 which are frictionally heated and reach the front side and go around the driving pulley 2 through a gap 17 or the like to cool.

The cooling air that has come into contact with the belt 1 and directly cooled, and the cover 10
The heat is transferred to the wall surface and released to the outside. The cover 10
If a large number of heat radiation fins (ribs) are formed on the outer and inner surfaces of the cover 10, the heat transfer area of the cover 10 becomes large and the release of the heat can be promoted.

When the flow after this is shown as an example of a dotted arrow as an example, first,
As shown by the arrow, it passes between the cover packing 13 and the drive pulley 2, enters the crank chamber C, and goes rearward (in the direction of arrow T). During this time, while circulating in the belt chamber B, the ambient temperature of the belt 1, the side surface of the crank chamber C, the belt chamber B, and the like are further cooled.

On the other hand, the cooling air diverted in the direction illustrated by the arrow E is directed toward the rear along the outer cover 12 while cooling the ambient temperature of the belt chamber and the belt 1, and as shown by the arrow H, the driven pulley 3 and the clutch. 9 and so on are cooled.

At this time, a gap 18 is formed between the clutch 9 and the outer cover 12.
Therefore, the cooling air can contact the entire circumference of the clutch 9 and exchange heat.

Further, as illustrated by an arrow L in FIG. 4, there is also a cooling air stream branched downward, and this cooling air stream is dispersed along the inner wall surface of the case 10 into the belt chamber B, and the cooling air is dispersed in the belt chamber B. B
Cool down to ambient temperature.

It should be noted that such a dispersion direction can be freely set depending on the shape of the inner wall surface of the belt including the inner wall surface of the case 10, the position of the discharge port 33, the directing direction, and the like.

The exhausted air, which has been cooled in this way, has risen above the ambient atmospheric temperature, so it rises in the belt chamber B, enters the exhaust port 16, and is exhausted to the outside through the exhaust passage 40. . Exhaust air that has cooled the drive pulley 2 and circulated from the front is also discharged together in the same manner.

As shown in FIG. 4, the flow of exhausted air in the vicinity of the exhaust port 16 first enters the exhaust passage 40 upward from the inlet 41, changes the direction downward at the curved portion 42, and eventually to the atmosphere from the exhaust port 43. Is discharged. The downward discharge port 43 can effectively prevent rainwater from entering the belt chamber B.

In this embodiment, the cooling fan conventionally provided for cooling the engine is commonly used for ventilation in the belt chamber,
All the cooling fans in the belt chamber can be omitted, and engine load and drive system loss can be significantly reduced.

Further, the ventilation passage 30 and the exhaust passage 40 are provided so as to be connected to the belt chamber B, and the outside air is forcedly blown to the ventilation passage 30 opening in the fan case, so that the ventilation in the belt chamber B is smooth. .

Moreover, in this embodiment, the discharge port 33 is adjacent to the crank chamber C and is arranged as far forward as possible, and the exhaust port 16 is provided at the rear end of the belt chamber B near the top of the outer peripheral portion of the driven pulley 3. Therefore, the distance between the discharge port 33 and the exhaust port 16 is large,
As a result, the contact area of the cooling air becomes large, and the ventilation efficiency of the entire belt chamber B is improved.

The present invention is not limited to the above-mentioned embodiment, and the electric fan can be operated only when the ambient temperature in the belt chamber becomes a certain temperature or more by controlling the temperature sensor provided in the belt chamber. In the low temperature state such as starting, it is more effective from the viewpoint of reducing the engine load.

Further, since the air passage need only have a hollow portion, it may be integrally formed with the crank chamber cover or the fan case cover itself, or may be a space formed by combining these members.

Note that the number of blowers is not limited, and a blower path dedicated to each of the central portion of the belt chamber and each of the driven and driven pulleys may be provided to blow air.

Further, the belt transmission device is not limited to the V-belt automatic transmission of the embodiment, but may be a simple belt winding transmission device that does not automatically shift. Therefore, the belt is also a flat belt, a circular cross section or a metal belt. The same effect can be used. Applications of this transmission include various vehicles and other industrial machines.

<Effects of the Invention> The present invention has a cooling fan attached to one end of a crankshaft,
A drive pulley is attached to the other end of the engine, a fan case containing the cooling fan is installed on one side of the engine, and a belt chamber is installed separately on the other side. The belt chamber and the fan case are hollow. Connected by a blower passage having a portion, and one end of the blower passage is opened to a high pressure portion formed in the fan case near the outer peripheral portion of the cooling fan, and the other end is near the drive pulley in the belt chamber. The cooling air is discharged in a direction that traverses the belt disposition plane, and an exhaust passage communicating with the outside air is opened near the driven pulley.

Therefore, the cooling air is discharged from the discharge port into the belt chamber in the direction crossing the belt disposing plane, so that the circulating flow in the belt disposing plane is positively diffused to disperse the heat in the entire belt chamber, and the mixed flow occurs. The temperature inside the belt chamber can be lowered by.

Moreover, since the ventilation can be efficiently performed, the life of the V-belt can be extended. In addition, since the cooling fan is provided on the crankshaft outside the belt chamber, loss of driving force can be reduced and power performance can be improved.

[Brief description of drawings]

1 to 4 show an embodiment of the present invention, FIG. 1 is a side view with a part omitted, FIG. 2 is a sectional view taken along the line II-II of FIG. 1, and FIG. FIG. 4 is a sectional view taken along the line IV-IV in FIG. (Explanation of symbols) C ... crank chamber, B ... belt chamber, M ... mission chamber, T ... V belt type automatic transmission (belt transmission device),
E ... Engine, F ... Fan case, FN ... Cooling fan, 1 ... Belt, 2 ... Drive pulley, 3 ... Driven pulley, 10 ... Cover, 16 ... Exhaust port, 20 ... Fan cover , 23 …… Suction port, 27 …… High pressure part, 30 …… Blower, 32
...... Blower, 33 …… Discharge, 40 …… Exhaust path.

Claims (1)

[Claims] 1. A belt transmission device comprising a substantially sealed belt chamber and a driving pulley, a driven pulley, and a belt wound in the belt chamber and wound between the pulleys in a vehicle-width direction. The cooling fan is attached to one end of the crankshaft, the drive pulley is attached to the other end with the engine in between, and the fan case containing the cooling fan is separated on one side of the engine and the belt chamber is separated on the other side. The belt chamber and the fan case,
They are connected by an air passage having a hollow portion, one end of the air passage is opened to a high pressure portion formed near the outer peripheral portion of the cooling fan in the fan case, and the other end is near the drive pulley in the belt chamber. A belt transmission device characterized in that an opening is made to discharge cooling air in a direction crossing a plane in which a belt is arranged, and an exhaust passage communicating with the outside air is opened near a driven pulley.