Endless belt for power transmitting

Details Endless belt for power transmitting Endless belt for power transmitting

2000-12-26

2003-03-04

Graham, Matthew C. (Department: 3683)

Endless belt power transmission systems or components

Friction drive belt

Including plural interconnected members each having a drive...

C474S242000

Reexamination Certificate

active

06527657

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to an endless belt used for power transmission to be used for a belt-type continuously variable transmission (CVT), especially to an endless belt for power transmitting, connecting link plates by pins.
DESCRIPTION OF THE PRIOR ART
One such endless belt for power transmitting has been developed by Van Doorne's Transmissie (VDT) in the Netherlands (VDT; see, for example, Japanese Patent No. 1105154). The VDT belt has layered steel bands with metal V-shape blocks inserted therebetween, and power is transmitted by contact between the sides of the V-shape blocks and sheave faces of primary and secondary pulleys.
In this VDT belt, biting pitch and polygon variation can be reduced by making the V-shape block thinner, and the VDT belt is noiseless. But, the above-mentioned layered steel belt is made of high price material, and should be produced at high accuracy. Besides, in this steel belt, slip loss occurs between steel belt layers in power transmission.
In order to solve the above-mentioned problems, an endless belt for power transmission as shown in Japanese Kokai publication number H7-91498, for instance, has been proposed. As shown in
FIG. 1
, the metal belt is comprised of a plural number of first and second blocks
2
,
3
located in a constant order in the longitudinal direction of a belt
1
, a plural number of link plates
5
which connect these blocks through pins
6
which are divided into two pins (rocker pins)
6
a,
6
b,
and spring means
7
stretching in the longitudinal direction of the link plate by engaging with these pins
6
. This endless belt for power transmission has three open holes
9
,
10
,
9
formed in the first and second blocks
2
,
3
, and the link chain
11
is seated in these open holes
9
,
10
,
9
. Since the pin
6
is engaged with the blocks
2
,
3
, the blocks
2
,
3
and the link chain
11
are mutually connected to form an endless chain.
Projections
2
a,
3
a
are formed so as to provide abutting surfaces between the first and the second blocks
2
,
3
and, on the opposite sides of the blocks
2
,
3
are slots
2
b,
3
b
for receiving divided pins
6
a,
6
b.
Within the first and second blocks
2
,
3
, the divided pins
6
a
and
6
b
are engaged with each other at their intermediate portions a, a and a predetermined clearance is formed at their outer end portions b, b. The pins
6
a,
6
b
are engaged with the pin engagement slots
2
b,
3
b
formed on the intermediate portions a, a so as to support each block
2
,
3
with each block being free to oscillate with respect to the pins
6
a,
6
b.
The outer side faces
2
c,
3
c
of each block
2
,
3
are inclined so as to adjust on the sheave side face of each pulley. Both outer end faces
6
c of the pins
6
may be inclined for adjusting to the sheaves. The pin end face
6
c
has R form orthogonal to the longitudinal direction of the belt, such as A—A section, for instance, and can contact with the sheave face on a pitch circle of the belt.
In the present endless belt
1
for power transmitting, torque is transmitted in such a manner that the torque of a pulley unit is transmitted from the sheave side face by contact with the first and the second blocks
2
,
3
and the pin
6
, and tensile force acts on the link chain
11
comprising the link plates
5
through the pins
6
.
In the above described metal endless belt
1
, both side faces
2
c,
3
c
of the first and the second blocks
2
,
3
are formed in the shape of almost a straight line; however, they may be shaped as an arc in which case they contact the sheave side along a straight line by elastic deformation. As the belt
1
begins to curve by biting into the pulley, changing from the straight line travel, then, both side faces of each block can start to contact the sheave side at any position along its radial dimension. The contact start position in the longitudinal direction of the belt changes in accordance with the position of the block in the radial direction.
For this reason, the blocks may start to contact with the sheave at their upper portion or lower portion, as determined by the shape of the side surfaces of the blocks
2
,
3
, with respect to the X-axis, the Y-axis or the Z-axis (as shown in
FIG. 1
, the longitudinal direction of the belt is X-axis, the right and left direction is Z-axis, and the up and down direction is Y-axis) and/or by the deformation of the sheave side and the block. The contact start position of the blocks
2
,
3
with the sheave in the longitudinal direction of the belt overlaps the pin
6
. That is, the contact of the blocks
2
,
3
with the sheave and the contact of the pin
6
with the sheave occur simultaneously.
In order to decrease undesired noise at the time of biting into the pulley by the metal endless belt
1
, it is preferable to make the biting pitch (contact start position interval in the circumference direction) as small as possible, and to decrease the angle between the adjacent belt contact positions with respect to the pulley center, that is, polygon variation (polygon effects). But, when the position of start of contact of the block with the sheave overlaps the pin as mentioned before, the angle between adjacent contact points increases, shifting the angle to be originally held between the block and the pin. Then, the biting pitch is increased to that extent, and undesired noise is increased.
On the other hand, if the shape of the end faces of the divided pins
6
a,
6
b
is a flat face along the side of the sheave or is the R shape with respect to the face orthogonal (radius direction) to the longitudinal direction of the belt, as in the above-mentioned prior art, above-mentioned (The R shape in the direction is the shape along the side of the sheave on the pitch circle, and is substantially the same as the above-mentioned flat face concerning the rotation of the pin at the time of biting), the relative clearance between the pin and the sheave is changed by the spin (rotation) of the pin when the belt bites into the pulley and the blocks and the divided pins are rotated to fit the effective diameter of the pulley. Then, the contact position between the pin and the sheave (in the circumferential direction and radial direction) is changed (change of the position where the pin starts to bite), and the above-mentioned polygon effects occur so as to cause undesired noise. At the same time, slip of the pin with respect to the sheave, especially the slip in the radial direction, increases.
Furthermore, by contacting the pin with the sheave at the position away from the rotational center of the pin, spin loss increases with the spin (rotation) of the pin. Besides, power loss occurs due to the change of the relative clearance between the pin and the sheave, especially by the slip in the radial direction, so as to reduce the power transmitting efficiency.
Thus, the first object of the present invention is to provide an endless belt for power transmission which is a tension-type belt using a link chain, having a high power transmitting capacity, which can be produced with relatively low cost, and having such a structure that the respective blocks and pins start to contact with the sheave side in order near the pitch line and the biting pitch into the sheave is made smaller so as to reduce noise.
The second object of the present invention is to provide an endless belt for power transmission, reducing the variation in pin width due to the rotation of the pin when the endless belt bites into the pulley so as to reduce undesired noise by the polygon effects and power loss by the spin of the pin.
SUMMARY OF THE INVENTION
The present invention provides an endless belt for power transmission having a plurality of divided pins (pin pairs) with rolling surfaces for abutting each other, a plurality of link plates comprising link chains alternately connected by said pins, and first and second blocks having projections capable of abutting each other, a concave slot provided on the side of each block, opposite the projection, for receiv

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