JPH0893858A - V belt for continuously variable transmission - Google Patents

Abstract

PURPOSE: To improve durability of a belt by way of avoiding increase in dishing as well as an upper cog jumping phenomenon by specifying a ratio of thickness of the center of a core wire body of a V belt in the thickness direction to an outer peripheral surface of a belt basis main body on the side of an upper cog and thickness to an inner peripheral surface of a belt basis main body on the side of a lower cog. CONSTITUTION: A belt 2 suspended between a stepless transmission drive pulley and a driven pulley has a side surface having an inclination which is larger than an inclination of a sandwiching surface of the pulley, and it is provided with an upper cog 5 on the outer peripheral side of a belt basis 7 with a core wire body 10 built in it and a lower cog 6 on the inner peripheral side through an adhesive material layer 11 integrally. In this case, a ratio T1/T2 of thickness T1 of a belt basis main body 8 on the upper cog 5 side from the center of the core wire body 10 in the belt thickness direction and thickness T2 of a belt basis main body 9 on the lower cog 6 side in the same way is set as 0.1 or more and 0.5 or less. Additionally, material hardness of the upper cog 5 and the upper cog side belt basis main body 8 is as more than material hardness of the lower cog 6 and the lower cog side belt basis main body 9.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a V-belt for a continuously variable transmission used in scooters, snow vehicles and the like.

[0002]

2. Description of the Related Art Generally, power transmission in a V-belt type continuously variable transmission is performed by friction between a driving side pulley and a driven side pulley and a belt wound around the pulleys, and in the above transmission. The speed change is performed by changing the axial distance between the pair of pulley halves by using centrifugal force or the like to change the belt winding diameter.

In the V-belt type continuously variable transmission as described above, it is necessary to increase the contact area between the V-belt and the pulley in order to efficiently transmit a large amount of power. On the other hand, if the above transmission is adopted for snow vehicles, scooters, etc.,
Although quick shift response is required, it is necessary to reduce the contact area in order to improve the shift response. In this case, it is necessary to reduce the contact area because the side surface of the belt that has been pressed against the pulley can be easily separated from the pressed portion of the pulley, and the frictional resistance when the belt slides on the pulley is reduced. This is because

Therefore, conventionally, as a structure of a V-belt and a pulley in which the contact area can be increased or decreased in accordance with the operating range, as shown in FIG. 6, the inclination angle β1 of the side surface 21a of the belt 21 is set. There is a structure that is set to be larger than the inclination angle β2 of the holding surface 20a of the pulley 20. Note that FIG.
FIG. 4 is a sectional view showing a belt winding portion of a pulley 20.

In this structure, in a driving range where the belt tension is relatively large and the belt clamping pressure of the pulley is high as in the steady operation, the belt is elastically deformed to increase the contact area between the belt and the pulley. Power can be transmitted sufficiently.

Further, in an operating region where the belt tension is relatively small and the belt clamping pressure of the pulley is low, such as during gear shifting, only the belt base portion above the core wire body 22 contacts the pulley so that the contact area is reduced. Since it becomes smaller, the shift response can be improved.

[0007]

However, in the above conventional structure, as shown in FIG. 7 (a sectional view taken along the line VII-VII in FIG. 6), the height dimension (t1) of the belt base 24 above the core wire 22 is increased. And the height dimension (t2) of the belt base body 23 below the core wire 22 is relatively large, for example, 0.8 or more. Therefore, even during steady operation in which the clamping pressure of the pulley is high, the ratio of the contact area of the upper belt base 24 portion to the total contact area of the belt 21 and the pulley 20 is large, and the surface of the upper belt base 24 portion is large. Since the pressure is high, the frictional force between the upper belt body 24 and the pulley 20 is as large as G2 as shown in FIG. Note that FIG. 8 is a side view schematically showing a pulley-wound portion of the belt 21.

On the other hand, the belt base body 23 below the core wire 22
The frictional force G3 between the portion and the pulley 20 is smaller than the upper frictional force G2. This is because the contact area of the portion of the belt base 23 below the core wire 22 is not smaller than that of the upper portion, but the surface pressure is low.

Therefore, the belt base 2 above the core wire 22
Belt tension G corresponding to 4 parts and the above frictional force G2 + G3
A large tensile load will act between the core wire 22 on which 1 acts. Therefore, in the conventional structure, there is a problem that a so-called upper-cog jump phenomenon occurs in which the belt 21 is broken by peeling off the joint portion of the belt base 24 above the core wire 22 and the core wire 22 by the adhesive layer 22a.

Since the V-belt is made of an elastic material, the V-belt is slightly dished (buckled) in the belt width direction even during steady operation, as shown in FIGS. This dishing becomes large especially in high load operation when the inclination angle in FIG. 6 is set to β1> β2. In this case, the core wires 22 at both ends of the belt
Will extend from the core wire 22 'in the middle portion, which means that a tensile load larger than that of the core wire 22' in the middle portion acts on the core wires 22 at the both ends. Therefore, when the rigidity of the belt in the width direction is low, the tensile load may exceed the breaking strength of the core wires 22 at both ends,
The problem that the belt is broken eventually occurs. 9 and 10 are a plan view and a cross-sectional view schematically showing the pulley-wound portion of the belt 21.

In general, the V-belt rotates while repeatedly reciprocatingly twisting during operation, and when the flexibility of the V-belt against twisting is low, the core wire 22 is used.
There is also a problem that stress due to the twisting motion is concentrated on the joint portion (adhesive material layer 22a) between the belt body 24 and the core wire 22 on the upper side, causing fatigue fracture, and eventually the belt 21 is fractured.

The present invention has been made in view of the above problems of the prior art, and provides a V-belt for a continuously variable transmission, which can avoid an increase in dishing as well as an increase in the cog jumping phenomenon, thereby improving the durability of the belt. Is intended.

[0013]

According to a first aspect of the present invention, an upper cog is provided on the outer peripheral side of a belt base body in which a core wire is provided between the upper cog side belt base body and the lower cog side belt base body. A V-belt for a continuously variable transmission, in which lower cogs are arranged on the circumferential side at a predetermined pitch in the longitudinal direction of the belt base body, and the upper cog side portion contacts the pulley when no load is applied. The thickness T1 from the center in the thickness direction to the outer peripheral surface of the upper cog side belt base body, and the thickness T2 from the center of the core wire body in the belt thickness direction to the inner peripheral surface of the lower cog side belt base body. The ratio T1 / T2 is characterized by being 0.1 or more and 0.5 or less.

According to a second aspect of the present invention, in the first aspect, the volume of the upper cog is set to be equal to or larger than the volume of the lower cog, and the material hardness of the upper cog and the upper cog side belt base body is set to the lower cog and the lower cog. It is characterized in that the hardness is set to be equal to or higher than the material hardness of the side belt base body.

According to a third aspect of the present invention, in the first or second aspect, the pitches of the upper cog and the lower cog are equal, and the recesses between the cogs are substantially aligned in the longitudinal direction.

Here, in the present invention, T1 / T2 is set to 0.
The reason why it is set to 1 to 0.5 is to make the above-mentioned frictional forces G2 and G3 substantially uniform. When T1 / T2 is larger than 0.5, the frictional force G2 on the upper cog side becomes larger than G3 as described above. On the other hand, if T1 / T2 is smaller than 0.1, the following problems may occur. For example, T2
When T1 / T2 is made smaller than 0.1 by increasing, the contact area with the pulley on the lower cog side increases,
The load on the lower cog side increases, and peeling easily occurs near the adhesive layer on the lower cog side. If T1 is reduced,
A crack is generated in the corner R of the concave portion of the upper cog, and the upper cog is easily damaged. Therefore, it is necessary to set T1 / T2 to 0.1 to 0.5.

[0017]

According to the V-belt for a continuously variable transmission of the present invention, the thickness T1 of the belt base body on the outer peripheral side of the core wire is
Since the ratio T1 / T2 with the thickness T2 of the belt base body on the inner peripheral side is set to an appropriate value of 0.1 or more and 0.5 or less, the occurrence of the upper cog phenomenon is prevented.

That is, the ratio between the height of the belt base body above the core wire and the height of the belt base body below the core wire is set to an appropriate value. Even in an operating range where the contact area with the pulley is large and the belt clamping pressure of the pulley is high, the contact area between the belt and the pulley and the friction force determined by the surface pressure applied to the contact portion are The belt base body on the upper side and the belt base body on the lower side of the core wire can be evenly distributed, and the frictional force is not biased to one of the base portions. Therefore, the tensile load generated between the core wire under tension and the belt base body in contact with the pulley acts on the upper and lower belt base bodies in a dispersed manner, and the adhesive layer for connecting the belt base body and the core wire The shear load on the part is reduced. As a result, the bonded portion due to the adhesive layer is not peeled off, and the upper cog jump phenomenon is prevented.

According to the V belt for a continuously variable transmission of the second aspect of the present invention, the volume of the upper cog is made larger than the volume of the lower cog, and the material hardness of the belt base body on the upper cog side and the upper cog side is
Since the material hardness of the lower cog and the belt base body on the lower cog side is made larger, the rigidity of the upper cog portion of the belt in the belt width direction can be improved. As a result, the dishing is suppressed, the elongation amount of the core wire, and thus the tensile load is made uniform, and the belt is prevented from breaking.

According to the V belt for a continuously variable transmission of the third aspect of the present invention, since the upper cog and the lower cog are formed at the same pitch and the recesses between the cogs are substantially aligned with each other, the belt is flexible against twisting of the belt. Therefore, the stress due to the reciprocal twisting motion repeatedly generated during the operation is prevented from being concentrated on the joint portion by the adhesive layer, and the breakage of the belt is prevented.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. 1 to 5 are views for explaining a V-belt for a continuously variable transmission according to an embodiment of the present invention, and FIGS. 1 and 2 are a side view and a plan view showing a state in which the belt is hung over a pulley. 3 is a sectional view taken along the line III-III in FIG. 1, FIG. 4 is a sectional view taken in the width direction of the V belt (a sectional view taken along line IV-IV in FIG. 5), and FIG. 5 is a sectional view taken in the longitudinal direction of the V belt. (VV line sectional view of FIG. 2)
Is.

In the figure, reference numeral 1 denotes a continuously variable transmission adopted in a snow vehicle, a scooter, or the like, which has a drive pulley 4 on the engine output shaft side and a driven pulley 3 on the rear wheel shaft side.
The belt 2 is stretched around. In this case,
As shown in, the inclination angle α1 of the side surface 2a of the belt 2 is set to be larger than the inclination angle α2 of the holding surface 3a of the pulleys 3 and 4. Each of the pulleys 3 and 4 is composed of two pulley halves which are movable in the axial direction, and the winding diameter is changed by changing the axial distance. 1 and 2, the winding diameter of the pulley 4 is minimized and the winding diameter of the pulley 3 is maximized.

The V-belt 2 has a structure in which an upper cog 5 is integrally formed on the outer peripheral side of a belt base 7 containing a core wire body 10 and a lower cog 6 is integrally formed on the inner peripheral side. The upper and lower cogs 5 and 6 have the same pitch P1 in the belt longitudinal direction.
And the upper cog recess 5 formed between the upper cogs 5 and 5.
The a and the lower cog recess 6a between the lower cogs 6 and 6 are arranged such that their positions in the belt longitudinal direction coincide with each other, and face each other with the belt base 7 interposed therebetween.

The belt base 7 has a structure in which a core wire body 10 is arranged between an upper cog side belt base body 8 and a lower cog side belt base body 9 and these are connected to each other by an adhesive layer 11. It is a thing.

The core wire 10 is made of polyester, aliphatic polyamide, aromatic polyamide, or high strength and low elongation rope tensile member such as glass fiber or wire twisted wire. It is buried in the shape. The adhesive layer 11 is made of NR (natural rubber), SBR (styrene / butadiene rubber), CR (chloroprene rubber), NBR (nitrile rubber), IIR.
(Butyl rubber), Hypalon (chlorosulfone ethylene), etc. A single material or a rubber in which these are appropriately blended, or a rubber-like elastic body such as polyurethane rubber, preferably a low-rigidity, low-hardness rubber compound as described above. .

The upper cog 5 and the upper cog side belt base body 8 and the lower cog 6 and the upper cog side belt base body 9 are, for example, aromatic polyamide, aliphatic polyamide, polyester,
CR (Chloroprene rubber) is made of short fibers of a few millimeters made of cotton thread, etc.
It is molded by mixing it with a rubber material such as.

Here, the thickness T1 of the upper cog side belt base body 8 and the thickness T2 of the lower cog side belt base body 9 are
T1 / T2 is set to be 0.1 or more and 0.5 or less. Specifically, T1 = 2 mm, T2 = 5 mm, T1
/T2=0.4. Also, the inclination angle β1-β2
Is set to 0.5 ° or more and 2 ° or less.

Further, although the upper cog 5 and the lower cog 6 have the same vertical cross-sectional shape shown in FIG. 5, the width dimension is L1> L2 as shown in FIG. The volume of the upper cog 5 is larger than that of the lower cog 6, and the material hardness of the upper cog 5 and the upper cog side belt base body 8 is larger than the material hardness of the lower cog 6 and the lower cog side belt base body 9. It is set.

Next, the function and effect of this embodiment will be described. In the transmission 1 of this embodiment, the rotational force of the pulley 4 is transmitted to the pulley 3 via the V belt 2. In this case, when the rotation speed of the pulley 4 on the engine side increases, the axial distance between the pulleys 4 decreases and the winding diameter increases, which increases the rotation speed of the rear wheels.

In the transmission of the power, each of the belts is set such that the ratio T1 / T2 of the thickness T1 of the upper cog side belt base body 8 and the thickness T2 of the lower cog side belt base body 9 is 0.4. Since the thickness of the base body is set appropriately, that is, the upper cog-side belt base body 8 is set thinner than the conventional one, so that the rotating belt 2 and pulley 3 are , 4 can be substantially evenly distributed to both the upper and lower cog side belt base bodies 8 and 9, and the frictional force between the upper cog side belt base body 8 and the pulleys 3 and 4 can be reduced. Therefore, the upper cog side belt base body 8 and the core wire body 10 can be prevented from peeling off and the V-belt 2 can be prevented from breaking.

Further, the volume of the upper cog 5 is made larger than that of the lower cog 6, and the material hardness of the upper cog 5 and the upper cog side belt base body 8 is the same as that of the lower cog 6 and the lower cog side belt base body 9. Since the hardness is made larger than the material hardness, the rigidity of the upper cog 5 in the belt width direction can be improved, and it is possible to avoid the increase in dishing that causes the belt to buckle in the belt width direction as in the conventional example described above. The amount of elongation, and thus the tensile load, is made uniform, so that the belt 2 can be prevented from breaking.

Further, since the upper and lower cogs 5 and 6 are arranged at the same pitch P1 as viewed in the longitudinal direction of the belt and the recesses between the cogs are aligned with each other, the flexibility against the twisting motion of the belt is improved. Therefore, it is possible to prevent the stress from being concentrated on the adhesive layer 11 having the weakest strength against the reciprocal twisting motion of the belt which is repeatedly generated during the operation, and thus the breakage of the belt 2 can be prevented more reliably.

Further, in this embodiment, when the upper cog 5 and the lower cog 6 have the same pitch, the belt longitudinal dimension and the pitch of the upper cog 5 are enlarged to match the pitch of the lower cog 6. , The rigidity of the entire V-belt 2 in the longitudinal direction (belt rotation direction) can be sufficiently secured, and acts on the adhesive layer 11. The stress distribution in the belt width direction can be made uniform, and the belt durability can be improved by the amount that the stress (maximum value) in the portion can be reduced.

[0034]

As described above, in the V-belt for a continuously variable transmission according to the invention of claim 1, the ratio of the thickness of the belt base body on the outer peripheral side to the thickness of the belt base body on the inner peripheral side is 0. 1 to
Since it is set to an appropriate value of 0.5, the frictional force between the belt base body on the outer peripheral side and the pulley can be reduced, the tensile load between the belt base and the core wire can be evenly distributed, and the durability of the belt can be improved. There is an effect that can improve.

In the V-belt for a continuously variable transmission according to the second aspect of the present invention, the volume of the upper cog is equal to or larger than the volume of the lower cog, and the material hardness of the upper cog and the belt base body on the upper cog side is lower cog and lower cog. Since the material hardness of the belt base body on the side is made equal to or more than the above, the rigidity in the width direction of the upper cog portion of the belt can be improved, the increase of dishing can be avoided, and the elongation of the core wire and the tensile load can be made uniform. Also has the effect of improving the durability of the belt.

In the continuously variable transmission V-belt according to the third aspect of the present invention, the upper cog and the lower cog are arranged at substantially the same pitch, and the recesses between the cogs are arranged substantially in the longitudinal direction of the belt. In addition, the flexibility of the belt against twisting can be improved, and the stress due to the reciprocal twisting motion of the belt can be prevented from concentrating on the adhesive layer, which also has the effect of improving the durability of the belt.

[Brief description of drawings]

FIG. 1 is a side view schematically showing a continuously variable transmission to which a V-belt according to an embodiment of the present invention is applied.

FIG. 2 is a schematic plan view of the apparatus of the above embodiment.

FIG. 3 is a sectional view taken along line III-III of FIG.

FIG. 4 is an enlarged cross-sectional view of the belt of Example V in the width direction.

FIG. 5 is an enlarged cross-sectional view of the belt of Example V in the longitudinal direction.

FIG. 6 is an enlarged cross-sectional view of a conventional V belt in the width direction.

FIG. 7 is an enlarged cross-sectional view of the conventional V belt in the longitudinal direction.

FIG. 8 is a schematic cross-sectional side view for explaining the relationship between the tension of the V-belt and the frictional force in the conventional transmission.

FIG. 9 is a schematic plan view for explaining the relationship between the tension of the V-belt and the frictional force in the conventional transmission.

FIG. 10 is a schematic cross-sectional plan view for explaining a problem of the V-belt in the conventional transmission.

[Explanation of symbols]

 2, 21 belt 5 upper cog 6 lower cog 7 belt base body 8 upper cog side belt base body 9 lower cog side belt base body 10 core wire body

Claims (3)

[Claims] 1. An upper cog is provided on the outer peripheral side of a belt base body in which a core wire is disposed between an upper cog side belt base body and a lower cog side belt base body, and a lower cog is provided on the inner peripheral side. A V-belt for a continuously variable transmission in which the upper cog side portion contacts the pulley when there is no load, the upper cog side belt base body is located from the center of the core wire body in the belt thickness direction. The ratio T1 / T2 of the thickness T1 to the outer peripheral surface of the main body and the thickness T2 from the center of the core wire body in the belt thickness direction to the inner peripheral surface of the lower cog side belt base body is:
A V-belt for a continuously variable transmission, which is 0.1 or more and 0.5 or less. 2. The volume of the upper cog is set to be equal to or larger than the volume of the lower cog, and the material hardness of the upper cog and the upper cog-side belt base body is set to the same as that of the lower cog and the lower cog-side belt base body. A V-belt for a continuously variable transmission characterized by being set to a material hardness or higher. 3. The upper cog according to claim 1 or 2,
A V-belt for a continuously variable transmission, wherein the lower cogs have the same pitch, and the recesses between the cogs are substantially aligned in the longitudinal direction.