JPS629061A - Vibration isolating construction for belt of belt transmission type stepless transmission - Google Patents

Abstract

PURPOSE:To improve durability of a belt by suppressing the flapping vibration of said V-belt and suppressing an internal heat generation due to the bending of said V-belt. CONSTITUTION:Shoes 33 made of a fluoroplastic, etc. are fixed to the inner surfaces of the upper and lower walls of a cover 8, near points at which a belt line 31 intersects a belt line 32. The shoe is installed in such a way that it keeps a proper clearance from the outer peripheral surface of the belt, and the outer peripheral surface of the shoe is formed into a contour to be suited to the belt line and so that the minimum clearance may not be varied to a large extent. Accordingly, the flapping vibration of the V-belt can be suppressed by providing the shoes 33, suppressing a heat generation due to the internal stress of the belt.

Description

Detailed Description of the Invention <Industrial Application Field> The present invention relates to a continuously variable transmission mainly used in a drive device of a motorcycle, and in particular to a belt having a guide means that can effectively suppress vibration of the belt. This invention relates to a belt vibration isolation structure for a continuously variable transmission.

<Prior Art> Continuously variable transmissions using belt transmission, which can vary the pitch circle radius of the drive and driven pulleys by utilizing centrifugal force or the like, have conventionally been used as driving force transmission devices for motorcycles.

<Problems to be Solved by the Invention> This type of belt transmission device has the disadvantage that the temperature of the belt rises due to heat generation due to friction between the belt and the pulley, resulting in loss of durability of the belt due to thermal fatigue. be. Regarding belt temperature rise, not only friction heat generation mentioned above but also
Heat generation is also caused by the internal friction of the belt structure itself due to belt bending and waving.In any case, in order to suppress belt temperature rise as much as possible, it is necessary to suppress belt vibration and eliminate unnecessary internal stress in the belt structure. It is preferable not to generate.

The present invention was made in view of the above findings, and its main purpose is to provide a belt vibration isolation structure for a belt chain type continuously variable transmission having a guide means that can effectively suppress belt vibration. It's about doing.

<Means for Solving the Problems> According to the present invention, such an object is achieved by a belt transmission type non-contact system consisting of a variable diameter drive pulley, a driven pulley, and a V-belt suspended between these pulleys. A guide which is a belt vibration isolation structure for a step-change transmission and is capable of sliding contact with the outer circumferential surface of the V-belt, which is located near the intersection of each belt line when viewed from the side at a maximum speed ratio and a minimum speed ratio. This is achieved by providing a belt vibration isolation structure for a belt-driven continuously variable transmission characterized by having a means.

In particular, it is preferable that the guide means be a shoe with a low coefficient of friction or a freely rotatable roller.

In this way, vertical undulation of the belt can be suppressed by the guide shoes or rollers, and heat generation due to unnecessary internal stress can be minimized, resulting in improved belt durability. It can be achieved.

Embodiments The present invention will now be described in detail with reference to specific embodiments with reference to the accompanying drawings.

FIG. 1 shows a drive device for, for example, a scooter to which the present invention is applied, in which a drive pulley 2 is attached to the crankshaft of an air-cooled gasoline engine 1, and the rotation of the engine 1 is controlled by a V-belt 3. is transmitted to the driven pulley 4 via.

The rotation of the driven pulley 4 is transmitted to a plurality of gears in a reducer 6 via a centrifugal clutch 5, and after being decelerated by the meshing of these gears, it is transmitted to a rear wheel 7 fixed to a drive shaft. . These drive devices are entirely covered with a cover 8 to prevent dust and raindrops from entering the drive devices.

FIG. 2 shows the main parts of the above-mentioned drive device.

A crankshaft 12 connected to the large end of the rod 11 is rotatably supported by the engine body 1, and a drive pulley 2 is attached to one end of the crankshaft 12. The drive pulley 2 includes a fixed drive pulley half 13 fixed to the shaft end of the crankshaft 12, and a fixed drive pulley half 13 fixed to the shaft end of the crankshaft 12.
It consists of a movable drive pulley half 14 which is axially (flexibly) supported with respect to the engine 1 and which moves radially outwards due to centrifugal force as the rotational speed of the engine 1 increases. The roller weight 15 is pressed axially towards the fixed drive pulley half 14.Therefore,
V formed by both drive pulley halves 13.14
The width of the groove is variable depending on the rotational speed of the engine. That is, as the rotational speed increases, the V-belt 3 is pushed up toward the outer circumference of the drive pulley 2, and as a result, the pitch circle radius is increased.

On the outer surface of the fixed drive pulley half 13, a fan blade 13a whose outer peripheral side is curved and extends in the radial direction is provided over the entire circumference. Outside air can be drawn into the cover 8.

The driven pulley 4 to which the rotational force of the engine 1 is transmitted through the V-belt 3 is a fixed driven pulley half 16.
and a movable driven pulley half 17, the fixed driven pulley half 16 is fixed to a hollow shaft 19 that is rotatably supported relative to the pulley shaft 18, and the movable driven pulley half 17 has an axis line on the outer peripheral surface of the hollow shaft 19. It is supported so as to be slidable in the direction. Furthermore, this movable driven pulley half 17 is biased toward the fixed driven pulley half 16 by the coil spring 22, and at low speeds, both driven pulley halves 16 and 17
The width of the V-groove formed by this is made to be the narrowest.

The pulley shaft 18 and the hollow shaft 19 are connected via the centrifugal clutch 5, and when the hollow shaft 19 to which the fixed driven pulley half 16 is fixed exceeds a predetermined rotation speed, the pulley shaft 18
The centrifugal clutch 5 is connected so that the shaft 19 and the hollow shaft 19 can rotate together, and the driving force of the engine 1 is transmitted to the pulley shaft 18.

Further, the fixed driven pulley half 16 and the movable driven pulley half 17 are connected by a torque cam mechanism (not shown), so that the pulley pitch radius is automatically changed according to running resistance.

The pulley shaft 18 meshes with a plurality of gears provided inside the reducer 6 and is connected to the drive shaft 21, and as described above, the tire 7 fixed to the drive shaft 21 is driven. .

Shoes 33 made of, for example, fluororesin are fixed to the inner surfaces of the upper and lower walls of the cover 8 in the vicinity of the intersection of the belt line 31 at the maximum speed ratio and the belt line 32 at the minimum speed ratio. ing. The shoe 33 is installed so as to maintain an appropriate clearance with the belt's outer circumferential surface when stopped, and the outer circumferential surface of the shoe 33 is formed in a contour that conforms to the belt line, so that it maintains a minimum clearance regardless of changes in speed ratio. The clearance is kept from changing significantly.

Since the tension of the V-belt 3 changes due to changes in the driving force,
In a vehicle transmission device in which speed and driving force constantly change, undulation of the V-belt 3 tends to occur relatively largely. However, by providing the shoe 33 described above, it is possible to suppress such vibrations, and it is possible to effectively suppress heat generation due to internal stress of the belt.

FIG. 4 shows a second embodiment of the present invention, in which the shoe 33 of the above embodiment is replaced with a roller 34 that can rotate when it comes into contact with the belt.

This embodiment is even more effective because no relative friction occurs when it comes into sliding contact with the belt.

<Effects of the Invention> As described above, according to the present invention, since the waving vibration of the V-belt can be effectively suppressed, internal heat generation due to unnecessary bending of the V-belt can be suppressed, and the durability of the belt can be improved. It can have a great effect on improvement.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing a drive system for a motorcycle to which the present invention is applied. FIG. 2 is a partially cutaway top view of the belt-driven continuously variable transmission according to the present invention. FIG. 3 is a side view showing the relationship between the boob and the belt. FIG. 4 is a side view of essential parts showing a second embodiment of the present invention. 1...Engine 2...Drive pulley 3.
...V-belt 4...Driven pulley 5...
Centrifugal clutch 6...Reducer 7...Rear wheel
8...Cover 8a...Outside air intake port 11...
・Connecting rod 12...Crankshaft 13...Fixed drive pulley half 13a...Fan blade 14...Movable drive pulley half 15...Roller weight

Claims (3)

[Claims] (1) Variable diameter drive pulley, driven pulley,
This is a belt vibration isolation structure for a belt transmission type continuously variable transmission consisting of a V-belt suspended between these pulleys. A belt vibration isolation structure for a belt-driven continuously variable transmission, characterized by having a guide means located in the vicinity and capable of slidingly contacting the outer circumferential surface of the V-belt. (2) The belt vibration isolation structure for a belt-driven continuously variable transmission according to claim 1, wherein the guide means is a shoe made of a material with a low coefficient of friction. (3) The belt vibration isolation structure for a belt-driven continuously variable transmission according to claim 1, wherein the guide means is a rotatable roller.