JPH0769000B2 - Transmission belt - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a transmission belt that is used by being stretched between V-groove pulleys of a continuously variable transmission or the like.

(Prior Art) This type of transmission belt includes an endless link connecting body in which a large number of parallel pins are mutually connected by link plates, and the endless link connecting body is sequentially arranged in the longitudinal direction thereof. It is usual to arrange them so that a V-shaped block is provided.

In practical use, this transmission belt is hung between the V-groove pulleys so that the V-shaped block frictionally engages with the pulley V-groove side wall. The power of the drive-side V-groove pulley is transmitted to the endless link connecting body via the V-shaped block frictionally engaging with the V-groove side wall,
After that, through the V-shaped block that frictionally engages with the V-groove side wall of the driven-side V-groove pulley, it reaches the driven-side V-groove pulley, and power can be transferred between both pulleys.

By the way, when each pin is a normal single cylindrical pin, a sliding contact between the pin and the link plate causes a link plate intersection angle, and the link plate intersection angle changes. The energy required for the sliding contact when unwinding from the pulley not only causes power loss, but also shortens the service life due to early wear of the sliding contact portion.

Therefore, as described in Japanese Patent Laid-Open No. 59-99142, each pin is used as two rocker joint pins to receive the belt tension by the abutting of the outer cylindrical surfaces of these rocker joint pins, and to roll these outer cylindrical surfaces. A transmission belt has been proposed in which the link plate cross angle is generated by the movement. In such a power transmission belt, the sliding contact portion is eliminated from the connecting portion between the link plates, and rolling contact is made, whereby power loss can be reduced and durability can be improved.

(Problems to be solved by the invention) However, in such a transmission belt, a large belt tension is applied between the outer cylindrical surfaces of the rocker joint pin during transmission of large power, and the surface pressure between these outer cylindrical surfaces is abnormally high. Become. In this case, peeling of the fatigue surface due to surface pressure such as pitching occurs, the rocker joint pin itself is damaged, and the durability is significantly reduced.

Therefore, since the above surface pressure, that is, the Hertz surface pressure is inversely proportional to the 1/2 power of the radius of curvature of the outer cylindrical surface, it is conceivable to increase the radius of curvature (decrease the curvature) to reduce the surface pressure. .

Then, when the diameter of the circular arc around which the belt is wound around the V-groove pulley changes, the rolling of the pair of rocker joint pins due to the change of the link plate intersection angle causes relative displacement of the link plates in the pitch line direction, and the belt circumferential length. Change. This change in circumference becomes more significant as the radius of curvature of the outer cylindrical surface of the rocker joint pin increases.
Rotational unevenness and tension fluctuations during belt running are increased, which causes new problems of vibration and noise.

(Means for Solving Problems) The present invention has a high frequency of use in the non-occurrence state of the link plate intersection angle (belt straight state), and when the practical maximum link plate intersection angle occurs (when the maximum gear ratio is selected), From the viewpoint that large power is often transmitted on steep slopes, etc., in the transmission belt of the above model, the outer cylindrical surface of the rocker joint pin is located near the contact position when the link plate intersection angle is not generated and the maximum practical link plate intersection angle is generated. A cylindrical surface with a small curvature is provided in at least one of the vicinity of the contact position at the time.

(Operation) The tension applied to the transmission belt during transmission from the driving pulley to the driven pulley is received by the abutment of the outer cylindrical surface of the rocker joint pin. In the pulley winding area, the link plate of the transmission belt can have an intersecting angle by rolling of the outer cylindrical surfaces, and the transmission belt can be along the pulley V groove.

By the way, during practical use of the power transmission belt, the rocker joint pin is predominantly present in the belt straight portion between the pulleys rather than the pulley winding area. No link plate intersection angle is generated in this belt straight portion, and at this time, the rocker joint pins of each pair abut each other at the portion of the outer cylindrical surface which is a small curvature cylinder. For this reason, the surface pressure between the outer cylindrical surfaces is low, and it is possible to prevent the rocker joint pin from being damaged and the durability from being lowered even if a large power is transmitted. Also, when the maximum gear ratio is selected, which often transmits a large amount of power, the link plate intersection angle becomes maximum in the small diameter (drive) side pulley wrapping region, but at this time, each pair of rocker joint pins has a small curvature of the outer cylindrical surface. The parts made into a cylinder contact each other. Therefore, in this case, the surface pressure applied between the outer cylindrical surfaces of the rocker joint pin in the small-diameter side pulley winding area is reduced, and its durability can be improved.

Moreover, in addition to the above, the rocker joint pins abut on each other at the outer cylindrical surface portion which is a cylinder of normal curvature, so that the belt circumference is not greatly changed, and vibration and noise are newly generated due to uneven rotation and tension fluctuations. It will never happen.

(Example) Hereinafter, the present invention will be described in detail based on an illustrated example.

1 to 3 show one embodiment of the transmission belt of the present invention, and 1 in FIG. 2 shows three endless link connecting bodies. Each endless link connecting body 1 is formed by connecting pins formed of two rocker joint pins 2 to each other by link plates 3 adjacent to each other. The three endless link connecting bodies 1 are juxtaposed so that their phases are shifted from each other by a half of the pin arrangement pitch, and a V-shaped block 4 that laterally surrounds these link connecting bodies 1 is arranged in the longitudinal direction of the link connecting body 1. To be sequentially fitted.

In practical use, as shown in FIG. 2 (c), the V-shaped block 4 is arranged so that the V-shaped block 4 is sequentially frictionally engaged with both side walls of the pulley V groove 5.
The transmission belt can be wound around the grooved pulleys, and the power can be transferred between the V grooved pulleys. As shown in FIG. 2 (b), the pair of rocker joint pins 2 receives the belt tension due to the abutment of the outer cylindrical surface 2a, and the link plate 3 is rolled by rolling the outer cylindrical surface 2a in the pulley winding area. An intersection angle is generated between them, which enables winding around the pulley.

In the illustrated example, as shown in FIG. 2 (b), each rocker joint pin 2 is provided with an impact contact on the outer cylindrical surface 2 a of the link plate 3.
Is connected to the corresponding link plate 3 at a set rolling angle α (see also FIG. 3) so as to be located on the inner peripheral side (lower side in the drawing) of the pitch line Z. For this connection, the inner circumference of the pin hole of each link plate 3 is partially projected in an inverted circular arc shape as shown by 3a, and the inner cylindrical surface 2b of the rocker joint pin 2 is fitted to this to prevent the rocker joint pin from rotating. I do.

Thus, when the link plate intersection angle θ shown in FIG. 2 (b) does not have the link plate intersection angle and the link plate intersection angle θ is generated as shown in FIG. 3 ″ are the corresponding rocker joint pins 2 ′, 2 ″ on the outer cylindrical surface 2a indicated by arrows a, b.
Rolling in the direction to make it possible to generate the link plate intersection angle θ. During this time, the contact point between the outer cylindrical surfaces 2a changes from A to B, and the contact point changes from B to C when the practical maximum link plate intersection angle occurs (when the pulley winding diameter is minimum).
Also, during this time, until the impact contact moves from A toward the center 0 of rotation of the link plate, the link plates 3'and 3 "are relatively displaced in the direction away from each other, increasing the belt circumferential length, While the contact point moves further and reaches B through C,
The link plates 3 ', 3 "are relatively displaced in the direction of approaching each other, and the belt circumferential length is reduced toward the original length.

In the present invention, the radius of curvature R of the outer cylindrical surface 2a is determined as described below with reference to FIGS. Fig. 4 shows the transmission of the transmission belt in the arrow direction when the maximum gear ratio is selected in the continuously variable transmission where the winding arc diameter of the drive pulley is the minimum value r _min and the winding arc diameter of the driven pulley is the maximum value r _max. Indicates the status. As is apparent from this state, the transmission belt starts from the position of the link plate intersection angle θ = 0 to the position where θ = θ _max corresponding to r _min , the position of θ = 0, and θ = θ corresponding to r _max. Return to the position after passing the _mid position. Therefore, it can be understood that the position of θ = 0 exists twice in one cycle, and the rocker joint pin outer cylindrical surface 2a abuts at the point A most frequently (for a long time) and becomes a neck of durability strength.

From this point of view, the present invention, as shown in FIG.
2a is a small-curvature cylindrical surface having a radius of curvature larger than the normal radius of curvature R ₀ centered on O ₁ by ΔR ₁ in a region X near the contact point A, and its center of curvature O ₂ is an adjacent region of radius R ₀ of curvature. It is arranged at a position that is smoothly continuous with the cylindrical surface portion in Y.

For this reason, if the rocker joint pin is present more frequently in the belt straight line portion between the pulleys than in the pulley winding region, the rocker joint pin in this belt straight line portion is mutually in the region X where the outer cylindrical surface is a small curvature cylinder. Even if the contact is made, the surface pressure is reduced and a large amount of power is transmitted, the durability of the rocker joint pin is not impaired.

In the pulley winding area, the rocker joint pins collide with each other in the area other than the X area of the outer cylindrical surface, and even if the outer cylindrical surface has a small curvature in the X area, this does not contribute to the change in the belt circumferential length. There is no new problem of vibration or noise due to uneven rotation or fluctuation of tension.

The maximum gear ratio selection state shown in FIG. 4 corresponds to the time of starting or the time of maximum load, and a large amount of power is often transmitted. Under such a state, a large surface pressure tends to be applied to the outer cylindrical surface abutting portions of the rocker joint pins. As for the straight belt portion, the surface pressure can be reduced by setting the X region to the cylindrical surface of small curvature as described above. However, if the same idea is applied to the driven-side pulley winding area, the winding length is long at the maximum, such as the winding arc diameter r _max , and the change in the belt circumference becomes extremely large, which is not preferable.

According to the present invention, if the surface pressure is reduced in the drive side pulley winding area by the same idea, the winding arc diameter is r
From the viewpoint that such a problem can be almost ignored because it is the minimum and the wrapping length is short like _min , as shown in FIG. 1, the outer cylindrical surface 2a is close to the contact point C when θ = θ _max. Also in the region W, a small-curvature cylindrical surface having a radius of curvature larger than the normal radius of curvature R ₀ by ΔR ₂ is arranged, and the center of curvature O ₃ thereof is arranged at a position so as to be smoothly continuous with the cylindrical surface portion in the Y region.

For this reason, when the maximum gear ratio, which often transmits large power, is selected, each pair of rocker joint pins in the drive side pulley winding area must abut against each other in the W region, which is a small curvature cylinder of the outer cylindrical surface. Therefore, if the surface pressure is lowered and a large amount of power is transmitted in many cases, the 雖 can prevent the durability of the rocker joint pin from being impaired.

(Effects of the Invention) As described above, in the transmission belt of the present invention, the outer cylindrical surface 2a of the rocker joint pin is provided in the vicinity of the contact position X when the link plate intersection angle is not generated and in the vicinity Z of the contact position when the maximum practical link intersection angle is generated. Since the cylindrical surface has a small curvature on at least one side, it is possible to reduce the surface pressure between the rocker joint pins 2 and improve the durability thereof while keeping the fluctuation width of the belt circumferential length small.

[Brief description of drawings]

FIG. 1 is an enlarged side view of an essential part showing an embodiment of a transmission belt of the present invention, FIG. 2 (a) is a partially cross-sectional plan view of the transmission belt of the same example, and FIGS. FIGS. 3A and 3B are BB and CC sectional views, FIG. 3 is an enlarged side view showing a link intersection angle generation state of the transmission belt of the same example, and FIG. is there. 1 …… Endless link connection 2 …… Rocker joint pin 2a …… Outer cylindrical surface 3 …… Link plate 4 …… V-shaped block 5 …… Pulley V groove Z …… Link plate pitch line W, X… … Small curvature cylindrical region θ …… Link plate intersection angle

Claims (1)

[Claims] 1. A V-shaped block comprising an endless link connecting body in which a large number of parallel pins are mutually connected by a link plate, and the endless link connecting body is sequentially arranged in the longitudinal direction of the endless link connecting body. In the transmission belt, each of the pins is used as two rocker joint pins to receive the belt tension by the abutting contact of the outer cylindrical surfaces, and the link plates generate an angle of intersection by rolling of the outer cylindrical surfaces. The outer cylindrical surface of the rocker joint pin is a small-curvature cylindrical surface in at least one of the vicinity of the contact position when the link plate intersection angle does not occur and the vicinity of the contact position when the practical maximum link intersection angle occurs. Transmission belt.