JPH0830517B2 - Block for transmission belt - Google Patents

Description

TECHNICAL FIELD The present invention relates to a block for a transmission belt used in a continuously variable transmission or the like.

[Conventional technology]

A belt for a continuously variable transmission used in a power transmission system of an automobile, a so-called CVT belt, which is stretched between a pair of pulleys 1 and 2 as illustrated in FIGS.
By changing the contact radius between the belts 1, 2 and the belt 3, an arbitrary gear ratio can be obtained steplessly.
This type of belt 3 includes a carrier band 4 and a large number of blocks 5 stacked in the longitudinal direction of the carrier band 4.
(Only a part is shown), and power is transmitted through these blocks 5.

The block 5 includes a pair of left and right inclined surfaces 6 that contact the pulleys 1 and 2, and a band hanging surface 7 that contacts the carrier band 4.
Are provided. Further, a convex portion 8 is provided on one surface side in the thickness direction of the block 5, and a concave portion (not shown) fitted to the convex portion 8 of the adjacent block 5 is provided on the other surface side. There is. Such a block 5 is also disclosed in, for example, JP-A-60-136650.

It is desirable that the lower half portion of the block 5 is formed in a tapered shape so that the blocks 5 can tilt in the front-rear direction according to the curvature when rotating on the pulleys 1 and 2. . For example, the conventional block 5 shown in FIG. 10 is formed in a taper shape such that the thickness on the bottom side of the block gradually decreases from the taper start line P as a boundary. For this reason, this block 5 is
As shown by the chain double-dashed line in FIG. 0, the taper start line P is used as the center of rotation to incline by the opening angle θ _{0 in the} front-rear direction. That is, since the blocks 5 always contact each other at the taper start line P, the taper start line P of each block 5 is in contact with each other.
A line segment P '(see FIG. 8) connecting the two becomes a pitch line.

When the durability test of the conventional belt 3 configured as described above is performed, the carrier band 4 and the band hanging surface 7 may be greatly worn, or the elongation of the carrier band 4 may exceed the allowable value. I found out the following.

[Problems to be solved by the invention]

In the power transmission system using the block 5, the carrier band 4 in contact with the block 5 on the pulley 2 on the large diameter side.
The radius of gyration of the inner peripheral surface of the is rb2 and the radius of gyration of the pitch line P'is
Is 2. On the other hand, on the small-diameter pulley 1, the radius of rotation of the inner peripheral surface of the carrier band 4 is rb1 and the radius of rotation of the pitch line P'is ra1. Therefore, the gear ratio (r
a2 / ra1) and the gear ratio of the inner peripheral surface of the carrier band 4 (rb2 /
Since rb1) is different from each other, when the belt 3 is rotated, the carrier band 4 and the block 5 are deviated from each other in angular velocity on the pulleys 1 and 2, and both of them cause relative slip on the belt hanging surface 7.

When the diameters of the pulleys 1 and 2 are different from each other, it is known experimentally and theoretically that the angular velocity of the carrier band 4 and the block 5 is constant on the pulley 2 on the large diameter side. That is, the relative slip between the carrier band 4 and the block 5 is
It occurs on the pulley 1 on the small diameter side. The speed va1 of the block 5 and the speed vb1 of the inner peripheral surface of the carrier band 4 at the point M (see FIG. 10) where the carrier band 4 and the block 5 contact each other on the small diameter pulley 1 are
Let ω2 be the angular velocity of, va1 = ra2 ・ ω2 (rb1 / ra1) ・ ・ ・ (1) vb1 ＝ rb2 ・ ω2 ・ ・ ・ (2) Therefore, the relative slip velocity (velocity difference) Δv1 at the contact point between the carrier band 4 and the block 5 on the small diameter side pulley 1 is Δv1 = va1−vb1 = ra2 · ω2 (rb1 / ra1) −rb2 · ω2 = {ra2 ( rb1 / ra1) -rb2} ω2 (3) and Δv1> 0, so block 5 precedes carrier band 4. For example, ra1 = 33.0mm, ra2 = 8
When 0.8mm, rb1 = 34.0mm, rb2 = 81.8mm, gear ratio = 2.452, drive side speed = 3000rpm, when ω2 is calculated, ω2 = (3000rpm / 2.452) × (1/60) × 2π = 128.124rad / sec. When the relative slip velocity Δv1 of the conventional block 5 on the small diameter side pulley 1 is obtained by substituting these conditions into the equation (3), Δv1 = 186 mm / sec, and the block 5 is equivalent to this velocity. It is ahead.

As described above, in the conventional power transmission system using the block 5, a large speed difference is generated between the carrier band 4 and the block 5. In addition, since the contact point where this speed difference occurs is also a section where the surface pressure between the two is high, it causes wear of the carrier band 4 and elongation of the band due to the rolling effect.
Further, when the blocks come into contact with each other beyond the normal opening angle θ ₀ for some reason, a large impact is generated between the blocks, which causes wear of the blocks.

Therefore, an object of the present invention is to reduce the relative sliding speed between the carrier band and the block on the pulley, and to allow the blocks to smoothly contact each other, so that the carrier belt and the block for the transmission belt that are less likely to be damaged. To provide.

[Means for solving problems]

In order to achieve the above-mentioned object, the present invention has a small-diameter circular arc surface whose thickness decreases from the band hanging surface side toward the block bottom side on at least one of the block front surface and the block rear surface that the blocks contact each other. A large-diameter circular arc surface having a larger radius of curvature than the small-diameter circular arc surface and a thickness decreasing toward the block bottom side is provided on the side where the small-diameter circular arc surface is provided continuously from the end. It is provided continuously.

[Action]

Like the conventional block, the block having the above configuration tilts in the front-rear direction when traveling on the pulley. However, in the case of the block of the present invention, when traveling on the pulley, the front and rear blocks come in contact with each other on a small-diameter circular arc surface, and the larger the opening angle of the block, the closer they are to the bottom of the block, that is, to the side where the thickness is smaller. become. Therefore, in the block of the present invention, when rotating on the pulley, the apparent plate thickness of the blocks arranged on the radius of rotation is reduced, so that the pitch between the blocks on the pulley is narrower than that of the conventional block, and as a result, the blocks are The peripheral speed of rotation is smaller than that of the conventional block. Such an effect is more prominent on the small diameter pulley in which the opening angle of the block is larger than when rotating on the large diameter pulley, and the speed difference between the carrier band and the block is reduced.

If the opening angle of the block exceeds the normal angle for some reason, the contact points of the blocks move from the small-diameter circular arc surface to the large-diameter circular arc surface, and the front and rear blocks come into contact with each other on the large-diameter circular arc surface. . Even in this large-diameter circular arc surface, the blocks come into contact with each other on the side where the thickness is thin, and the contact points between the blocks change according to the inclination of the blocks. Therefore, the impact due to the defective behavior of the block can be softened, which is also effective in reducing the wear of the block.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 5.

The block 10 of this embodiment is the conventional block 5 described above.
Similarly to the above, a plurality of carrier bands 4 are used in a stacked state in the longitudinal direction. The material of the block 10 may be cermet, ceramics or the like, in addition to ferrous metal and non-ferrous metal. The carrier band 4 may be the same as the conventional one, and has a multilayer structure in which a plurality of thin endless steam bands are stacked in the thickness direction.

The block 10 is provided with a pair of left and right inclined surfaces 11 that contact the slopes of the V-shaped grooves of the pulleys 1 and 2, and a pair of left and right band hanging surfaces 12.
The inner peripheral surface of is in slidable contact. Also, the head of block 5
A convex portion 14 is provided on one surface side in the thickness direction of 13 and a concave portion 15 is provided on the other surface side at a position corresponding to the convex portion 14, and the convex portion 14 and the concave portion are formed by adjacent blocks. 15 fits together. Since the thickness t of the head 13 located above the band hanging surface 12 is substantially constant, the head 13 has a flat shape in a side view. The thickness t is 2.3 mm as an example.

A small-diameter circular arc surface 17 and a large-diameter circular arc surface 18 are provided on the front side in the traveling direction of the block 5. As shown in FIG. 1, the small-diameter circular arc surface 17 is provided in the range of the length l from the point A which is the end of the band hanging surface 12 to the point B located below the point. The thickness of the small-diameter circular arc surface 17 decreases from the band hanging surface 12 side toward the block bottom portion 20 side. The center C of the radius of curvature r1 of the small-diameter circular arc surface 17 is on the straight line m extending from the point A in the direction opposite to the traveling direction of the block 10.

The radius r1 of the small-diameter circular arc surface 17 is, for example, 5 mm. The angle θ ₁ formed by the tangent line n at the point B and the head 13 is larger than the maximum value θ ₀ (for example, 4.0 °) of the normal opening angle on the small diameter pulley 1, for example, θ ₁ = 5.7 °. In this case, the distance 1 between A and B is about 0.5 mm.

On the other hand, the large-diameter circular arc surface 18 is a small-diameter circular arc surface at point B above.
A center (not shown) of the large-diameter circular arc surface 18 is provided on the normal line H of the point B so as to be in smooth contact with the point 17. Moreover, the radius r2 of the large-diameter circular arc surface 18 is much larger than the radius r1 of the small-diameter circular arc surface 17, for example r2 = 50 mm. The large-diameter circular arc surface 18 also decreases in thickness toward the block bottom 20 side.

When the block 10 having the above structure travels on the large-diameter pulley 2, the opening angle of the block 10 becomes θ ₃ as shown in FIG. ₃ , and the blocks 10 are in contact with each other between the small-diameter circular arc surfaces A and B. . Also, when traveling on the small diameter side pulley 1,
As shown in FIG. 4, the opening angle of the block 10 widens to θ ₀ , and the block 10 comes into contact at a position near the point B. In this way, the blocks 10 contact each other on the small-diameter circular arc surfaces 17, and the larger the opening angle of the blocks 10, the closer the blocks 10 are to each other, that is, the sides where the thickness is smaller are in contact with each other. Therefore, the apparent thickness of the block 10 when traveling on the large-diameter pulley 2 is t2, and the apparent thickness on the small-diameter pulley 1 is t1, which is t1 <t2 <t with respect to the original thickness t of the block 10. The relationship is established.

As described above, the pitch between the blocks 10 is narrowed on the pulleys 1 and 2, but the radius of rotation of the contact position of the block 10 with the pulleys 1 and 2 is determined according to the groove width of the V-shaped groove of the pulleys 1 and 2. Therefore, the rotational peripheral speed of each block 10 on the pitch line P'is smaller than that of the conventional block. Such an effect is obtained by the small-diameter pulley 1 having a large opening angle of the block 10.
Appears noticeably above.

The radius of gyration of the pitch line P ′ of each block 10 on the large-diameter pulley 2 and the small-diameter pulley 1 is the same as that of the conventional block 5.
Different from the case of, set ra2 ′ and ra1 ′ respectively (second
Figure). Here, when the angular velocity of the large diameter pulley 2 is ω2, the carrier band 4 and the block 10 are arranged on the small diameter pulley 1.
At the point of contact with, the speed va1 of the block 10 is va1 ′ ＝ ra2 ′ ・ ω2 (t1 / t2) ・ (rb1 / ra1 ′) ……
It is represented by (4). Further, since the radius of gyration of the contact position of the block 10 with respect to the pulleys 1 and 2 is determined according to the groove width of the V-shaped groove of the pulleys 1 and 2, the carrier band 4 in contact with the block 10 on the large-diameter pulley 2 has a large radius. Since the radius of gyration of the inner peripheral surface is rb2, which is the same as that of the conventional block 5, the velocity vb1 of the inner peripheral surface of the carrier band 4 is represented by vb1 = rb2 · ω2, which is This is the same as the formula (2) of the block. Therefore, by comparing the equations (4) and (1), it is understood that the speed of the block 10 can be reduced by {(t1 / t2). (Ra2 '/ ra1')} / (ra2 / ra1). At this time, the relative slip velocity Δv1 ′ of the block 10 with respect to the carrier band 4 is Δv1 ′ = va1′−vb1 = {ra2 ′ (t1 / t2) · (rb1 / ra1 ′) − rb2} ω2, and (ra2 / ra1 )> (T1 / t2) ・ (ra2 ′ / ra1 ′), it becomes smaller than the relative sliding speed of the conventional block.

Fig. 5 shows radius r1 of small-diameter circular arc surface 17 and relative slip velocity Δv1 '
Shows the relationship with. Since the relative sliding speed in the above-mentioned conventional block 5 was 186 mm / sec, in the case of this embodiment, if r1 is 21 mm or less, (ra2 / ra1)> (t1 / t2). (Ra2 '/ ra1' ) Is satisfied, and the relative velocity Δv1 can be made smaller than before. That is, the smaller the r1, the smaller the relative slip velocity Δv1 can be made. However, if r1 becomes too small, the contact surface pressure between the blocks becomes large, and wear progresses, which is not preferable. From such a viewpoint, according to the research conducted by the present inventors, favorable results were obtained in the range of 2.0 ≦ r1 / t ≦ 9.2.

As described above, when the blocks 10 are traveling in an ideal state, the blocks 10 contact each other on the small-diameter circular arc surface 17, but for some reason the block 10 behaves in a defective manner and the opening angle exceeds θ ₁ . In case of, the contact point of the block 10 moves to the large-diameter circular arc surface 18 side. Even in this large-diameter circular arc surface 18, as the opening angle of the block 10 becomes larger, the blocks come into contact with each other on the thinner side, so that the apparent thickness of the block 10 becomes larger.
t1 becomes smaller. Moreover, the positions of the contact points of the blocks 10 change according to the opening angle of the blocks. Therefore, even when the block 10 behaves in a defective manner, the blocks 10 can smoothly contact each other along the arcuate surface 18, and the occurrence of impact can be suppressed. Moreover, since the position of the contact point continuously changes each time the radius of rotation of the block 10 with respect to the pulleys 1 and 2 changes, it is also effective in reducing the wear of the block 10.

Although the large-diameter circular arc surface 18 is a part of a perfect circle in the above embodiment, the large-diameter circular arc surface 18 may be a part of an ellipse or an ellipse in carrying out the present invention.

Further, in the present invention, a small-diameter circular arc surface 17 and a large-diameter circular arc surface 18 may be provided on the side opposite to the traveling direction (rear surface side) as in the other embodiment shown in FIG. 6, or As in the embodiment shown in FIG. 7, a small-diameter circular arc surface 17 and a large-diameter circular arc surface 18 may be provided on both front and rear surfaces.

〔The invention's effect〕

As described above, according to the present invention, the speed difference between the carrier band and the block can be reduced by pressing the preceding speed of the block on the small-diameter pulley that causes relative slippage, and moreover the front and rear blocks can be made smaller. Even if the opening is large, the blocks can contact each other smoothly along the arc surface. Therefore, the carrier band and the block are less likely to be worn or damaged, and the band is prevented from being stretched due to the rolling effect caused by the carrier band being rubbed on the band hanging surface.

[Brief description of drawings]

1 to 5 show an embodiment of the present invention. FIG. 1 is a side view of a block, FIG. 2 is a schematic side view showing a power transmission system, and FIGS. 3 and 4 are block diagrams respectively. FIG. 5 is a side view when the opening angle is different, FIG. 5 is a view showing the relationship between the radius of the small-diameter circular arc surface and the relative sliding speed, and FIGS. 6 and 7 are blocks showing other embodiments of the present invention. A side view, FIG. 8 is a schematic side view of a power transmission system using a conventional block, FIG. 9 is a front view of the conventional block, and FIG. 10 is a side view of the conventional block. 1,2 …… Pulley, 4 …… Carrier band, 10 …… Block, 12 …… Band hanging surface, 17 …… Small diameter circular arc surface, 18 …… Large diameter circular arc surface.

Claims (1)

[Claims] 1. A transmission belt block, which is held by a carrier band passed between a pair of pulleys and is used by stacking a plurality of carrier bands in the longitudinal direction thereof, each block being a part of the carrier band. A small-diameter circular arc having a band-engaging surface with which the peripheral surface slidably contacts, and at least one of the block front surface and the block rear surface with which the blocks contact each other, whose thickness decreases from the band-engaging surface side to the block bottom side. The surface is continuously provided from the end of the band hanging surface, and on the side where the small diameter circular arc surface is provided, the radius of curvature is larger than that of the small diameter circular arc surface and the thickness decreases toward the block bottom side. A transmission belt block characterized in that an arcuate surface is continuously provided on the small-diameter arcuate surface.