Variable speed transmission device

A flexible transmission device for continuously variable transmissions comprises an endless flexible connecting element and a plurality of transverse links. Each link includes at least one groove into which is engaged the flexible connecting element. The transmission element operates dry, without lubrication. The transmission stirrups, or links, of the transmission element are arranged around an endless core. The endless core is configured in the form of a V-belt. The endless core has oblique walls in contact with interior surfaces of the stirrups or links. The exterior oblique surfaces of the stirrups or links, are in contact with the flanges of the transmission pulleys.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to the field of variable speed mechanical 
power transmission systems, which systems include a mechanism for the 
transmission of power between grooved pulleys wherein the transmission 
system includes at least one endless belt having a plurality of transverse 
links positioned thereon. Such systems include flexible elements, or 
belts, that operate by dry adherence, that is, without externally provided 
lubrication between the grooved pulleys. The belt may include an interior 
V-shaped endless loop with a plurality of thrust links positioned thereon. 
The grooved pulleys may have fixed cheeks or flanges, or also, as is often 
used in variable speed transmissions, the pulleys may have movable cheeks 
or flanges. Both types of pulleys and/or transmissions are encountered in 
automotive applications and on agricultural and industrial equipment. 
The variable feature of such systems is achieved by relative displacement 
between the pairs of cheeks, or flanges, of one or more pulleys of the 
system. Such systems may employ drive and/or receiver pulleys that have 
conical belt engagement surfaces to provide variable diameters thereof. 
Such systems may operate by dry mechanical adherence. The power 
transmission element in the form of a flexible belt transfers mechanical 
power between the pulleys of such transmission systems. The belt includes 
an interior endless loop. 
2. Background Information 
This application claims priority from French Patent Application No. 9 004 
162. French Patent Application No. 9 004 162, in turn, is a Certificate of 
Continuation filed pursuant to a French principal application filed Jan. 
11, 1988. This French principal application filed Jan. 11, 1988 is 
identified as French Patent Publication No. 2 625 783 and French 
Application Serial No. 88 00244 ("FR '244") and is entitled "Transmission 
Mechanism for Infinitely Variable Transmission With Transverse Thrust 
Links and Flexible Core, Operating by Dry Friction." U.S. Pat. No. 
4,968,288, issued Nov. 6, 1990, ("U.S. '288") claims priority from FR 
'244. 
The list of prior art described in U.S. '288 can be supplemented by the 
addition of West German Patent Publication No. 2,557,724. West German 
Patent Publication No. 2,557,724, assigned to Hans Heynau GmbH, discloses 
links of transmission elements having matching contact surfaces between 
the links. The matching contact surfaces are provided to ensure transverse 
integrity, solidarity, adherence and/or contact among the links. 
French Patent Publication No. 2,540,953, assigned to Regie Nationale Des 
Usines Renault et Compagnie Des Produits Industriels De L'Ouest, discloses 
a transmission system having links. The links have centering pins and 
matching holes to ensure the transverse integrity, solidarity, adherence 
and/or contact between staples and/or riders of the system. 
Characteristics of this transmission system include the configuration of 
the contact surface of the links and the configuration of the band that 
forms a flexible core of the system. 
European Patent Publication No. 0,073,962, assigned to Nissan Motor 
Company, Limited, discloses staples and/or riders, formed by blocks that 
are positioned sequentially in a first position and a second position 
relative to an endless band, or belt. The second position is rotated 
180.degree. from the first position about the axis. The axis is 
perpendicular to the longitudinal plane defined by the endless band. The 
blocks are equipped with pins and holes. The blocks are relatively 
positioned such that the pins of one block fit within the holes of an 
adjacent block. 
U.S. Pat. No. 4,433,965 to Hattori is assigned to Nippondenso Co. Ltd., and 
U.S. Pat. No. 4,610,648 to Miranti is assigned to Dayco Corporation. These 
two U.S. patents disclose transmission systems having flexible cores. The 
flexible cores include flat belts that support links. The links are 
constructed of modified polymers or composites and are reinforced, as 
necessary, with short fibers. 
In summary, all of the above-cited patent documents relate, essentially, to 
a flexible belt having a flexible core. The flexible core being a flat 
band, strip, or super-imposition or stack of metal bands. 
In actual use, all of the devices disclosed in the above-recited patent 
documents are extremely unstable when the power belt is traveling in the 
straight line portion of its trajectory, such as between two pulleys. The 
instability is the result of thrust on and/or through the belt. Such 
thrust is exerted by reciprocal contact between the aligned links of the 
belt. This problem of instability was already known at the time of the 
filing of FR '244. The particular embodiment of the invention shown in 
FIG. 7 of FR '244 and the subject of Claim 22 of FR '244 attempted to 
remedy such instability. 
During actual use of the device of FIG. 7 of FR '244, however, it was 
determined that even the coincidence between the imaginary, or predicted, 
original line of travel of the thrust links and the travel of the neutral 
fiber of the loop did not ensure stability of the device. Therefore, the 
stability of the device may be inadequate when significant and high 
mechanical power must be transmitted through the device. 
OBJECTS OF THE INVENTION 
One object of the present invention is to provide an improved variable 
speed power transmission belt that solves the problems of the prior art by 
providing stirrups or links for variable speed transmissions, such as the 
transmissions disclosed in FR '244, so that the transmission element 
provides improved and stable performance. Another object of the present 
invention is to provide a loop for a belt. Additionally, another object of 
the present invention is to provide a functional configuration of the 
contact zone between the loop of the belt and the thrust links positioned 
on the loop Further, another object of the present invention is to provide 
a functional design of the thrust links of the belt. 
SUMMARY OF THE INVENTION 
The present invention provides a more stable transmission system than known 
systems. The present invention provides a belt that employs as a core a 
V-belt of conventional dimensions. The V-belt may have a trapezoidal cross 
sectional configuration. The V-belt shaped loop takes place between 
surfaces having little or no relative movement therebetween. Such contact 
between surfaces makes possible an improved distribution of stresses in 
the belt and, consequently, reduces heating of the belt during operation. 
The present invention includes a belt for an infinitely variable 
transmission employing transverse thrust links. The thrust links are 
similar to those disclosed in FR '244. The present invention provides an 
improvement over the belt disclosed in FR '244 in that the loop is a 
V-belt having oblique walls. The oblique walls of the V-belt are in 
contact with the interior surfaces of the stirrup shaped thrust links. The 
thrust links are positioned on, and surround at least a portion of the 
V-belt. The exterior oblique surfaces of the links, in turn, are 
configured to come into periodic contact with the cheeks, or flanges, of 
the transmission pulleys of the transmission systems in which the pulleys 
are employed. 
In summary, one aspect of the invention resides broadly in a continuously 
variable speed transmission comprising: a drive pulley; a driven pulley; 
each of the drive pulley and the driven pulley having conical surfaces to 
provide variable diameters thereof; a transmission mechanism extending 
around each of the drive pulley and the driven pulley; the transmission 
mechanism including at least one endless flexible connecting element; the 
endless flexible connecting element defining a generally trapezoidal cross 
section; the transmission mechanism including a plurality of links mounted 
on the endless flexible connecting element; and each of the links 
including at least one groove means for receipt of the endless flexible 
connecting element therein. 
Another aspect of the invention resides broadly in a continuously variable 
speed transmission belt for a continuously variable speed transmission, 
the transmission having a drive pulley and a driven pulley, the 
transmission belt for extending movably around the drive pulley and the 
driven pulley, the drive pulley for driving the driven pulley by the 
transmission belt, the belt comprising: a flexible loop of material; the 
flexible loop having a substantially trapezoidal cross section; a 
plurality of substantially rigid links mounted on the flexible loop; the 
links each defining a cavity for receiving a portion of the flexible loop, 
the cavity being configured to correspond substantially to a portion of 
the flexible loop cross section; the links each having an exterior 
perimeter surface defining an at least partially trapezoidal cross 
section; each link having opposed contact surfaces connected to the 
exterior perimeter surface; each link contact surface for being in 
removable contact with an adjacent the contact surface of an adjacent 
link; each link contact surface being configured to push the adjacent 
contact surface of the adjacent link to move the belt along the path of 
travel; a flexible cover substantially surrounding the exterior perimeter 
surface of each link; and the flexible cover extending generally 
continuously along generally the entire length of the belt.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
FIG. 1A shows power transmission system 100. Transmission system 100 
includes belt 102. Belt 102 is positioned on, and travels between, pulleys 
104 and 106. One of pulleys 104 and 106 may be a drive pulley while the 
other of pulleys 104 and 106 may be a receiver pulley. 
FIG. 1B shows an assembly of several transversally rigid links 1. Links 1 
are assembled in alignment on loop 2. The portion of belt 102 shown in 
FIG. 1B corresponds to a portion of straight line trajectory portion 108 
of transmission element 102 (See FIG. 1A). The transmission ratio of 
transmission system 100 can be varied by changing radius R1 and/or R2 of 
pulleys 104 and/or 106, respectively, as is well known in the art. 
The majority of the power transmission by belt 102 is accomplished by the 
reciprocal contact between parallel surfaces 3 of adjacent links 1. 
Oblique surfaces 4 of links 1 are generally symmetrically defined by links 
1, as shown in FIG. 1B. 
The relative configuration of adjacent oblique surfaces 4 of adjacent links 
1 facilitates the winding of belt 102 around pulleys 104 and 106 since 
adjacent oblique surfaces 4 o adjacent links 1 are out of contact with one 
another along straight line trajectory portions 108 and 110. However, such 
adjacent oblique surfaces 4 pivot toward and may at least partially 
contact one another when their associated links 1 exit straight line 
trajectory portions 108 and 110 and wind around pulleys 104 and 106. Also, 
adjacent parallel surfaces 3 pivot away from one another when their 
associated links 1 exit straight line trajectory portions 108 and 110 and 
wind around pulleys 104 and 106. 
However, when adjacent links 1 assume a straight line trajectory along 
straight line trajectory portions 108 and 110, their respective oblique 
surfaces 4 are pivoted away from one another to the relative configuration 
shown in FIG. 1B. 
A gradual surface configuration transition exists at the junction of 
parallel surfaces 3 and oblique surfaces 4 of each link 1. Link 1 may be 
made of a high-modulus polymer material. 
FIG. 2 shows loop 2 which defines interior V-belt 21. V-belt 21 may have a 
trapezoidal cross-sectional configuration. Loop 2 defines oblique walls 5. 
Oblique walls 5 may either be "bare" (known commonly as a "raw-edge" type 
of belt) or oblique walls 5 may be covered by a fabric (known commonly as 
a "covered" type of belt). Oblique walls 5 are configured and positioned 
to be in contact with interior walls 10 of links 1. Exterior surface 6 of 
link 1 defines a large base area of loop 2. 
Reinforcement elements 7 are positioned within elastomer compound base 8. 
Reinforcement elements 7 are, frequently, constructed of a high-modulus 
textile material. Reinforcement elements 7 are intimately bonded to 
elastomer compound base 8 by physico-chemical or physio-chemical means. 
Reinforcement elements 7 are, also, bonded to elements that are resistant 
to transverse compression and which extend to small base 9 of V-belt 21. 
Reinforcement elements 7 may comprise a neutral fiber of V-belt 21. 
The oblique walls 5, of each link 1, that are wound around the pulleys 104 
and 106, are in contact with their respective surfaces 10 of each 
respective link 1. Also, when links 1 are being wound around pulleys 104 
and 106, exterior oblique surfaces 11 are in direct contact with the 
respective flanges of pulleys 104 and 106. The angle that exterior oblique 
surfaces 11 form relative to line 22 is not necessarily the same as the 
angle that interior surfaces 10 form relative, also, to line 22. 
Links 1 include lateral staples, or flanges, 12. Staples 12 are positioned 
on either side of and in contact with exterior surface 6 of loop 2. The 
separation between edges 12a and 12b along surface 6 is selected based on 
the elasticity of the particular V-belt 21 over which the particular 
staple 12 will be positioned. Such separation is selected such that each 
link 1 can be forcibly engaged over V-belt 21 during assembly of link 1 
onto loop 2. 
After assembly of belt 102, the very small surfaces, of lateral staple 12 
that contact exterior surface 6 prevent link 1 from falling out of 
engagement with V-belt 21. Such disengagement of link 1 from V-belt 21 is 
prevented even when link 1 is positioned and moving along straight line 
trajectory portions 108 and 110. Moreover, such disengagement of link 1 
from V-belt 21 is prevented even when a portion of belt 102 is slack. Belt 
102 is considered "slack" when adjacent links 1 are not in contact with 
one another. Experience has shown that it is preferable to have coating 6a 
on exterior surface 6. Coating 6a, preferably, has a low coefficient of 
friction relative to the surface of staple 12 in which it is in contact. 
Coating 6a may be advantageously composed of a very high molecular weight 
polyethylene film or ethylene polytetrafluoride. 
Each link 1, preferably, defines centering pins 13 and cavities 14. A 
centering pin 13 of one link 1 is configured to be received within a 
corresponding cavity 14 of an adjacent link 1. Centering pin 13 and cavity 
14 form a guiding device. Employment of centering pin 13 and cavity 14 as 
a guiding device does not affect the contact that occurs between interior 
surfaces 10 of link 1 and oblique walls 5 of loop 2. 
The contact pressure against interior surfaces 10 and oblique walls 5 may 
vary such that a very rapid variation of stresses within belt 102 may 
occur during passage of belt 102 from either of straight line trajectory 
portions 108 and 110 to one of pulleys 104 and 106. With the present 
invention, the contact pressure exerted between interior surfaces 10 and 
oblique walls 5, which remain in generally permanent contact with one 
another, is continuous. With a conventional V-belt not employing links 
such as links 1, however, each point of such a belt is only periodically 
in contact with the flanges of the pulleys. 
Since the imaginary original lines, or predicted path of travel of links 1, 
coincide with the region of the neutral fiber adjacent reinforcement 7, no 
separation between constituent materials is necessary during operation. 
Micro-displacements can occur in the zone of, and between, lateral staples 
12 and exterior surface 6. Such micro-displacements can occur because 
parallel surfaces 3 pivot away from one another along those portions of 
belt 102 that are wound around pulleys 104 and 106. Further, the length of 
surface 6 increases along those portions of belt 102 that are wound around 
pulleys 104 and 106 in contrast to those portions of belt 102 that are 
positioned along straight line trajectory portions 108 and 110. For this 
reason, coating or covering 6a, which has a low coefficient of friction, 
is considered necessary to allow for such micro-displacements between 
staples 12 and surface 6. However, both surface 6 and coating or covering 
6a must retain a degree of deformability that is compatible with the 
flexing of belt 102. 
Below the neutral fiber, in the zone of the elements that are resistant to 
transverse compression, the tapered shape of oblique surfaces 4 reduces 
the contact surface between them and loop 2, to a fraction of the surface 
of belt 102 which is elastically deformable in flexure. 
During the winding of belt 102 around pulleys 104 and 106, adjacent oblique 
surfaces 4 of adjacent links 1 move, or pivot, toward one another. Such 
movement, in turn, causes a volumetric compression of the portion of loop 
2 that is located between the neutral fiber of reinforcement 7 and small 
base 9. 
Loop 2 may be a conventional V-belt of standardized dimensions. Such a 
V-belt may be used for conventional industrial or automobile applications. 
When such a conventional V-belt is employed as loop 2 such a belt may 
accept stresses that are significantly higher than the maximum stresses 
specified when such belts are used for conventional purposes. Therefore, 
belt 102 may be used in applications requiring much higher mechanical 
power transfer than possible with conventional belts. Belt 102 may 
experience surface stresses that are very much higher than those stresses 
experienced by conventional belts in typical known applications. It has 
been shown that power transmitted through belt 102 is distributed such 
that about one-third of the tension within belt 102 is transmitted by 
V-belt 21 of loop 2. Two-thirds of the tension within belt 102 is 
transmitted by and through the reciprocal contact between adjacent links 
1. With belt 102 of the present invention, the stresses in belt 102 are 
much more evenly distributed due to the compression of, generally, the 
entire surface area of oblique walls 5 of V-belt 21. 
Also, compressive forces, generally of the same order of magnitude as those 
applied to oblique walls 5, are exerted in an analogous manner on exterior 
oblique surfaces 11 of link 1. Such compressive forces on exterior oblique 
surfaces 11 cause surfaces 11 to become somewhat flattened by contact with 
the flanges of the pulleys. 
The risks of high alternating stresses in zone E (shown in FIG. 2), when 
the magnitude of such stresses are calculated by the finite element method 
as described in French Publication No. 2625783, are significantly reduced 
by the present invention due to the utilization by the present invention 
of loop 2 that is in the form of V-belt 21. The employment of such a loop 
2 by the present invention is why the mechanical power transmitted by belt 
102 can be much higher than possible when using conventional belts. 
FIGS. 3A and 3B show another embodiment of the present invention. Closed, 
or closable, link 15 further minimizes the risk of alternating fatigue due 
to stresses within the belt. 
Closable link 15 is engaged with loop 2 in a different manner than is link 
1. Closable link 15 is, merely, positioned around a portion of loop 2, 
when strap 16 is in the open position as shown in FIG. 3A. Link 1, on the 
other hand, may be engaged or snapped, over loop 2 only by forcing staples 
12 over exterior surface 6 of loop 2. Strap 16 is articulately connected 
to link 15 by hinge 17. Hinge 17 permits strap 16 to be closed over loop 
2. FIG. 3A shows closable link 15 with strap 16 opened. FIG. 3B shows link 
15 in place on loop 2 with strap 16 closed. Strap 16 is held in the closed 
position, for example, by notch 23 defined by edge 18. 
Preferably, cavities 19 are formed in the body of closable link 15. 
Cavities 19 are configured to receive their corresponding lugs 20 that are 
on strap 16. Other arrangements of cavities 19 and lugs 20 are possible. 
For example, cavities 19 may be formed in strap 16 and lugs 20 may be 
located on the body of closable link 15. Also, at least one cavity 19 and 
at least one lug 20 may each be located on each of strap 16 and lug 20. 
The exterior contour of each of links 1 and 15 is symmetrical once 
installed on loop 2. Therefore, link 1 and 15 may be assembled in any 
desired and functional orientation on loop 2. 
Closable link 15 defines somewhat of a beam that is, under optimum 
conditions, resistant to compression exerted on exterior oblique surfaces 
11. Generally, the lower portion of closable link 15 is not as thick as 
the thickness between the oblique surfaces 11 and interior surfaces 10, on 
account of the existence of the oblique faces. 
Belt 102 may be used in the same applications as would a conventional, wide 
V-belt. With the employment of belt 102, transverse compression 
reinforcement is provided by the links 1 and 15 that are positioned 
external to loop 2. 
A preferred fabrication process for belt 102 includes the initial step of 
the fabrication of links 1 and/or links 15. Such fabrication may take 
place by mass production molding of a composite polymer material that is 
reinforced with short fibers. 
V-belt 21 is, preferably, formed by the superimposition of reinforcement 
element 7 around a mandrel. Such reinforcement element 7 is preferably 
embedded in polymer or elastomer compound base 8. Polymer, or elastomer, 
compound base 8 is intimately bonded, preferably by physico-chemical, or 
physio-chemical, adherence to reinforcement element 7. Reinforcement 
element 7, preferably, consists of wire or short fibers of high modulus 
material such as, preferably, textile material. Also, polymer or elastomer 
compound base 8 is intimately bonded to the compression resistant element 
which extends downward from the neutral fiber reinforcement adjacent 
element 7 of loop 2. The portion of loop 2 that includes the compression 
resistance elements may be formed by the stacking of layers of cord coated 
with polymer compound. Also, that portion may be formed by stacking sheets 
of polymer compound that are reinforced by oriented short fibers. Such 
reinforcing ensures the transverse rigidity necessary for the V-shaped 
belt 21 of loop 2. 
A belt covering, comprising a material having a low coefficient of friction 
such as very high molecular weight polyethylene or ethylene 
polytetrafluoride may be positioned around the exterior of loop 2. The 
covering may be intimately bonded by physico-chemical, or physio-chemical, 
adherence to large base 24 of loop 2. Such physico-chemical or 
physio-chemical, adherence may be performed by vulcanization. An 
appropriate guide process may be employed to ensure the assembly of either 
of links 1 or 15 on loop 2. Such a process may be employed irrespective of 
whether the walls of loop 2 are covered or bare. In the case of closable 
links 15, the closing of straps 16 is followed, if necessary, by a 
continuous heat sealing process along the two lines defined by the 
plurality of lugs 13 of the closable links 15. Such sealing may be 
performed by ultrasound, by a cyanoacrylate adhesive process or any other 
similar process. 
The number of links 1 and/or 15 mounted on loop 2, for a given length of 
belt 102, is checked to make certain that there is a specified amount of 
"play", or slack, in belt 102. Such slack should be within specified 
maximum and minimum tolerances when belt 102 is disposed about pulleys 104 
and 106. The slack is absorbed when belt 102 winds around pulleys 104 and 
106 and when belt 102 assumes a position along straight line trajectory 
portions 108 and 110. 
Belt 102 operates dry, that is without lubrication. Belt 102 can provide 
power transmission capabilities in a compact form. Such power transmission 
capabilities are significantly greater than those capabilities possible if 
a conventional V-belt alone were employed to transmit the power without 
the use of links 1 and/or 15. In fact, belt 102 may provide an increase in 
power transmission capabilities by a factor of almost three over the power 
transmission capabilities of conventional V-belts. 
The present invention provides the designers of power transmission systems 
with a high-performance, flexible transmission element that does not 
require delicate manufacturing and/or installation techniques or the 
employment of complex new technologies. The present invention employs 
components whose manufacturing processes are familiar and reliable and 
which manufacturing processes require only limited tooling irrespective of 
the lengths of the transmission elements to be fabricated. 
FIG. 4 shows power transmission system 1a', which includes mechanical power 
transmission belt 1'. Belt 1' is employed as a flexible mechanical power 
transmission belt. Belt 1' includes loop 2' which is preferable an endless 
loop. Belt 1' is, preferably, at least partially concealed by covering 
fabric 3'. Loop 2' is partially enclosed by rigid links 4'. In other 
words, a plurality of links 4' are positioned on and at least partially 
surround loop 2'. The disclosed stacking or positioning, of links 4' on 
loop 2' permits belt 1' to transmit power from drive pulley 6' to receiver 
pulley 5', essentially, by the reciprocal thrust of the links 4'. In other 
words, drive pulley 6' supplies mechanical power to the links 4' that are 
in immediate contact, through fabric 3', with drive pulley 6'. Those links 
4' that are in immediate contact with drive pulley 6', through fabric 3', 
transfer the mechanical power through the stack of links 4' in the 
direction of arrow D'. Transfer of mechanical power through the stack of 
links 4' occurs by reciprocal, physical contact between parallel surfaces 
7' (shown in FIG. 5) of adjacent links 4'. In other words, the links 4' in 
immediate contact with drive pulley 6' transfer power by applying a force 
on the first adjacent link 4' positioned along, generally, straight belt 
portion 27'. That first link 4', in turn, pushes on the next adjacent link 
4' in the direction of arrow D'. Such reciprocal pushing of adjacent links 
4' in the direction of arrow D' is generally continuous along the entire 
extent of belt portion 27'. The stack of rigid links 4' along belt portion 
27', in turn, transfers the mechanical power therein to the links 4' that 
are in immediate contact, through fabric 3', with receiver pulley 5'. 
Those links 4' in immediate contact through fabric 3', with receiver 
pulley 5' then transfer the mechanical power to receiver pulley 5'. 
With such mechanical power transmission occurring through links 4', loop 2' 
is used exclusively for the guidance and support of links 4', even though 
loop 2' is held tightly between pulleys 5' and 6'. 
In contrast, the use of a conventional V-belt were to be used in place of 
belt 1', such a conventional V-belt would transfer mechanical power by 
exerting a force from drive pulley 6' to receiver pulley 5' by a tension 
differential between a driving portion of the conventional V-belt and by a 
slack portion of the conventional V-belt. With such a conventional V-belt, 
the driving portion of the conventional V-belt would be under high tension 
and the slack portion of the conventional V-belt would be under low 
tension. If such a conventional V-belt were employed in lieu of belt 1' of 
the present invention, the slack portion of the conventional V-belt would 
correspond to belt portion 27' and the driving portion of the conventional 
V-belt would correspond to, generally, straight belt portion 28'. Belt 1' 
may function somewhat as the equivalent of a combination of these two 
types of operations. In other words, belt 1' may exhibit properties 
similar to a combination, or hybrid, of the high and low tension functions 
of the above described conventional V-belt. 
Receiver pulley 5' and drive pulley 6' may be a part of a variable ratio 
transmission system. With such a variable ratio transmission system, one 
flange of at least one of drive pulley 6' and receiver pulley 5' is 
axially displaceable relative to the other flange of the same pulley. The 
specific means for accomplishing such axial displacement is well known to 
those of ordinary skill in the art. Such variable ratio systems may employ 
known drive and/or receiver pulleys that have conical belt engagement 
surfaces that provide a variety of diameters of the pulley over which the 
belt travels. It is possible to achieve an increase in operational 
performance of both fixed-ratio and variable-ratio transmission systems by 
employing a flexible belt, such as belt 1' according to the present 
invention. Fixed ratio transmission systems, typically, employ grooved 
pulleys having a constant width. In other words, in fixed-ratio systems, 
the separation between the flanges of the pulleys is constant since the 
flanges of each pulley are not relatively axially displaceable. Also, it 
is possible that such fixed-ratio systems may not employ conical belt 
engagement surfaces. 
FIG. 5 shows several links 4' positioned astride loop 2'. In FIG. 5' links 
4' are shown positioned laterally along the straight line trajectory of 
belt portion 27'. Thus, the fragment of belt portion 27' depicted in FIG. 
5 is shown inverted from the orientation of belt portion 27' as shown in 
FIG. 7. The power transmission from drive pulley 6' to receiver pulley 5' 
is achieved, for the most part, by the reciprocal thrust, or contact, 
between adjacent pairs of links 4' at adjacent parallel surfaces 7'. 
Oblique surfaces 8' are, generally, symmetrically defined by each link 
4'.The relative configuration of adjacent oblique surfaces 8', of adjacent 
links 4', facilitates the winding of belt 1' around pulleys 5' and 6' 
since adjacent oblique surfaces 8' pivot toward one another when their 
associated links 4' are wound around pulleys 5' and 6'. However, when 
adjacent links 4' assume a straight line trajectory, such as those rigid 
links 4' positioned along belt portions 27' and 28', their respective 
oblique surfaces 8' are pivoted away from one another to the relative 
configuration as shown in FIG. 5. 
In another embodiment of the present invention (not shown), only one 
oblique surface 8' is provided for each link 4'. The other surface of such 
link 4' then has one continuous and, generally, straight surface 7' 
extending from generally the top to the bottom of such rigid link 4'. 
As portions of belt 1' move from a straight line trajectory, such as along 
belt portions 27' and 28', to a curved trajectory, such as when wound 
around one of pulleys 5' and 6', a displacement of loop 2' may occur in 
the vicinity of contact zone C' between two adjacent links 4'. Links 4' 
may be made of reinforced, high-modulus polymer materials or may be made 
of metal. 
An important feature of the present invention is the construction of loop 
2'. Loop 2' may define a V-belt 31'. The term "V-belt" refers to a belt 
that may be in the shape of a "V" or a trapezoid or truncated "V". V-belt 
31' may be of conventional, composite structure Loop 2' may also include 
traction layer 9'. Traction layer 9' may be formed of cables and/or 
high-modulus twisted textile fibers. In one preferred embodiment of the 
present invention, traction layer 9' is formed of aramid fibers. The 
aramid fibers of traction layer 9' may be treated so that they are 
intimately bonded to elastomer compound base 13' (see FIG. 6) of V-belt 
31'. 
Surrounding, or covering, fabric 3' is shown positioned partially on the 
stack of links 4' in FIG. 5. The use of fabric 3' in the present invention 
may necessitate the employment of bevels 11' on generally each of the 
peripheral surfaces of links 4'. Bevels 11' allow for the deformability of 
fabric 3' in the vicinity of zone 10' during passage of links 4' from a 
curved trajectory, when wound on one of pulleys 5' and 6', to a straight 
line trajectory, such as along belt portions 27' and 28'. Adjacent links 
4' pivot on one another in the vicinity of contact zone C' as the adjacent 
links 4' move between straight and curved trajectories. As a pair of 
adjacent links 4' move from a straight trajectory to a curved trajectory, 
adjacent parallel surfaces 7' pivot away from one another and adjacent 
oblique surfaces 8' pivot toward one another. On the other hand, as 
adjacent links 4' move from a curved trajectory to a straight trajectory, 
adjacent parallel surfaces 7' pivot toward and into contact with one 
another and adjacent oblique surfaces 8' pivot away from one another. 
To facilitate such relative movement between adjacent links 4', fabric 3', 
which consists of an elastic fabric coated with an elastomer compound, is 
slackened longitudinally in the vicinity of zone 10'. Fabric 3', is also 
in contact with the front surface of link 4'. The portions of fabric 3' in 
contact with bevels 11' are able to conform, generally, to the outer 
contour of bevels 11' due to the simultaneous adherization and 
vulcanization of the elastomer compound used to impregnate, or coat, the 
elastic fabric that forms fabric 3'. 
Fabric 3', may advantageously be oriented obliquely relative to composite 
V-belt 31'. Also, fabric 3' may be formed in a single thickness or in 
multiple thicknesses. 
Loop 2' may define a covered V-belt 31'. However, as shown in FIG. 6, loop 
2' defines a raw-edged V-belt 31'. When V-belt 31' has such raw edges, 
oblique walls 12' are formed by cutting a cylindrical sleeve of the 
material used to form V-belt 31'. The cut cylindrical sleeve may then be 
positioned adjacent and attached to a very long traction layer 9'. 
Traction layer 9' may be embedded in elastomer compound base 13'. 
Traction layer 9' may consist of a cord, twisted aramid fibers or another 
high-modulus textile material that is preferable chemically treated to 
achieve an intimate bonding with elastomer compound base 13'. Interior 
surfaces 14', of link 4', are positioned, substantially, in contact with 
oblique walls 12' of loop 2' as shown in FIG. 6. 
Loop 2' may be reinforced in trapezoidal-shaped zone 29' between traction 
layer 9' and small base 15'. Such reinforcement may be either by textile 
plys or by short fibers. Such reinforcement is provided to resist the 
compression of the belt due to the "wedge effect." Such a "wedge effect" 
may occur due to forces applied on oblique walls 12' by interior surfaces 
14'. Such a "wedge effect" may occur to the links 4' that are wound on a 
pulley 5' or 6'. The reinforced portion of loop 2' may be longitudinally 
elastic, or resilient. When belt 1' is wound around a pulley, the 
reinforced portion of zone 29' is somewhat flattened against interior 
surfaces 14' of links 4'. Since links 4' include angled, or bevelled, 
interior surfaces 14', as shown in FIG. 6, portions of interior surfaces 
14' may participate in the volumetric compression of the portion of loop 
2' located between the neutral fiber at the level of, or near, traction 
layer 9' and small base 15'. 
Stresses that are significantly higher than those encountered during the 
current usage of conventional V-belts can be exerted by the rigid, 
interior surfaces 14' of links 4' along the curved trajectory of belt 
portions around the pulleys 5' and 6'. Interior surfaces 14' of links 4', 
preferably, do not separate from oblique walls 12' when links 4' move in 
their straight line trajectory along belt portions 27' and 28'. Rather, 
interior surfaces 14' remain in contact with oblique walls 12', without 
applying any stress to loop 2' during such straight line trajectory 
movement. 
However, those portions of loop 2' that are wound on a pulley encounter 
pressures or forces that are of the same order of magnitude as those 
applied to the sides 30' of the links. Such pressures or forces may be due 
to the compression of loop 2', such as may be due to the "wedge effect", 
as described above. Such pressures are exerted in a similar manner as 
those applied to conventional V-belts. Such pressures or forces, are 
exerted through sides 30' of links 4' due to force applied to links 4' by 
contact with the flanges of the pulleys. 
The risks of alternating stresses are significantly reduced with the 
present invention due to the utilization of a loop 2' that is in the form 
of V-belt 31'. The employment of such a V-belt 31' permits the mechanical 
powers transmitted by belt 1' to be much higher than those transmitted 
with a standard V-belt, as explained in greater detail below. 
Links 4' remain stacked and under compression at parallel surfaces 7' in 
the vicinity of contact zone C' along belt portion 27'. However, belt 
portion 28' is somewhat slack. Under such circumstances, adjacent links 4' 
of belt portion 28' may not necessarily be in contact with one another. 
Therefore, links 4' of belt portion 28' may become separated from loop 2' 
and may even become totally disengaged from loop 2' due to the effects of 
gravity. 
To eliminate the risk of separation of links 4' from loop 2', lateral 
staples 16' are fitted on links 4'. These staples 16' partially enclose 
large base 17' of loop 2' to secure links 4' to loop 2'. Links 4' are 
assembled with loop 2' by, preferably, forcing links 4' over the naturally 
elastic or resilient loop 2' which loop 2' is not reinforced above the 
neutral fiber between traction layer 9' and large base 17'. 
As portions of belt 1' move between the curved trajectory and the straight 
line trajectory, the part of loop 2' between traction layer 9' and large 
base 17' is subjected to an elastic, or resilient, variation of length. 
However, links 4' do not, similarly, exhibit such a variation in length in 
the vicinity of lateral staples 16'. Therefore, longitudinal 
micro-slippage can occur between loop 2' and lateral staples 16'. Because 
of the possible slippage, it is advantageous to provide large base 17' 
with coating 18'. Coating 18', preferably, has a low coefficient of 
friction. Such a coating 18' may be, for example, a thin film of very high 
molecular weight polyethylene or ethylene polytetrafluoride. Thus, the 
coefficient of friction between large base 17' and lateral staples 16' is 
low. 
Fabric 3' may cover all, or only a portion, of the exterior surfaces of 
links 4'. Fabric 3' may be fixed to sides 30' of links 4' by a thermal 
treatment subsequent to assembly of belt 1'. Depending on the application 
for which belt 1' is to be used, the continuity of fabric 3' can be 
interrupted adjacent to each lateral staple 16' as shown in FIG. 6 or 
continued to thereby cover large base 17'. However, fabric 3' may, 
possibly, not adhere to large base 17' because coating 18' has a low 
coefficient of friction. 
FIG. 7 is a top view of one link 4'. FIG. 7 shows the presence of bevels 
11' on the extremities of link 4'. The purpose of bevels 11' is to allow 
deformability of fabric 3'. Upper portions 19' of bevels 11' also cover 
the area in the vicinity of lateral staples 16'. Upper portions 19' help 
to keep the interrupted edge of fabric 3' affixed to the links 4', 
particularly when centrifugal force is exerted as belt 1' winds around 
pulleys 5' and 6'. For applications at relatively low speeds, fabric 3' 
can be closed over itself by mutually engaged, overlapping portions. The 
mutual fastening of the overlapping portions may occur in the vicinity of 
coating 18' of large base 17'. Since fabric 3' may not be intimately 
bonded to coating 18', micro-displacements between fabric 3' and links 4' 
may occur. 
FIGS. 8A and 8B show another embodiment of link 4' of the present 
invention. In this embodiment, closable, or closed, link 20' includes 
strap 21'. Strap 21', when closed, causes closable link 20' to generally 
surround an entire cross section of loop 2'. This embodiment of the 
present invention minimizes the risks of fatigue due to the alternating 
stresses that may be localized in the bevelled, or angled, portions of 
links 4'. Such alternating stresses may occur at points in the 
non-closable links 4' which are open in a "U" shape, shown in FIGS. 4-7 
and described above, where the thickness is reduced. 
FIG. 8A is a partial view of closable link 20' in the open position. FIG. 
8B shows closable link 20' in the closed position. As shown in FIG. 8B, 
strap 21' is positioned adjacent loop 2' when strap 21' is in the closed 
position. Closable link 20' and strap 21' are connected together in an 
articulated manner by hinge 22'. Hinge 22' is produced during the molding 
of closable link 20'. 
A system for assembling the components of belt 1' should, preferably, be 
capable of being automated to achieve a high rate of production of belts 
1' that employ closable link 20'. In such automated systems, strap 21' is 
closed by an appropriate guide element after the associated closable link 
20' is installed astride loop 2'. Edge 23', that may be temporarily 
clipped, is provided to hold the end of strap 21' therein when strap 21' 
is in the closed position as shown in FIG. 8B. Such a closing of strap 21' 
is provided by the engagement of corresponding lugs 25', of strap 21' in 
matching cavities 24'. 
Three arrangements of lugs 25' and cavities 24' are possible. In one 
arrangement, all of cavities 24' are formed in the body of closable, or 
closed, link 20', and all of matching lugs 25' are positioned on strap 
21'. In another arrangement, all of cavities 24' are formed in strap 21' 
and all of matching lugs 25' are positioned on the body of closable link 
20'. In a third arrangement, at least one each of cavities 24' and 
matching lugs 25' are on the body of closable link 20' and at least one 
each of cavities 24' and matching lugs 25' are on strap 21'. 
A continuous heat-sealing process using e.g. ultrasound, or an adhesive 
fastening process using e.g. cyanoacrylate adhesive, or any similar 
assembly process may be used to finally close straps 21' over loop 2'. 
Closable link 20', as shown in FIG. 8B, is configured to resist alternating 
fatigue. Such resistance to alternating fatigue is desirable since 
closable link 20' may possibly receive high compression stresses on its 
interior surfaces 14' and oblique walls 12'. 
During assembly, the number of links 4' or closed links 20' is selected, 
for a given length of belt 1', to provide a belt that may have some play 
after the belt is installed between two pulleys. Such play may be 
absorbed, or compensated for, during the passage of belt 1' between the 
lowest winding radii on the pulleys and the portion of belt travel along 
the two straight line trajectories. Because of the rocking of adjacent 
links in the vicinity of contact zones C', the number of links 4' or 
closable links 20' required to construct a belt 1' for a given power 
transmission la, (see FIG. 4), is greater than the number of links 4' 
required to construct a belt 1' of a length that would be required when 
power transmission 1a' is of a circular configuration. 
Also, allowance for play in belt 1' must be made during the installation of 
fabric 3' over links 4' or 20'. To encourage the micro-displacements that 
occur between loop 2' and straps 21', large base 17' of loop 2' is, 
preferably, provided with coating 18'. The coefficient of friction between 
loop 2' and straps 21' is, generally, lowered because of coating 18'. 
Closable links 20' are, preferably, covered with fabric 3' to improve the 
friction of exterior oblique surfaces 26' against the flanges of pulleys 
5' and 6'. Fabric 3' is, preferably, glued only to exterior oblique 
surfaces 26'. The presence of fabric 3' is not essential on the top and 
bottom bases of the trapezoid-shaped closable link 20'. However, the 
elasticity of fabric 3', contributes to balancing the play between 
adjacent links 20'. Such elasticity may occur due to a partial bonding by 
adhesive to closable link 20' along bevels 11'. Bevels 11' run along each 
of the corners of closable link 20'. 
The inclusion of fabric 3' on closable link 20', also, may provide a 
certain amount of vibration damping during reciprocal rocking of adjacent 
closable links 20' in the vicinity of contact zone C'. Fabric 3' can be 
closed and made to adhere to itself through the reciprocal engagement of 
overlapping portions of adjacent strap 21', as shown in FIG. 8B. 
A preferred process for the fabrication of belt 1' of the present invention 
includes two heat cycles for each component. Links 4' or closable links 
20' are, initially, fabricated by molding. Such molding may be performed 
by injection molding techniques. When using such injection molding 
techniques, a closed mold having a large number of impressions may be 
employed. The material used for molding links 4' or 20' may, for example, 
include semi-aromatic polyamide that is, preferably, reinforced with short 
fibers. The number of the molded impressions can be on the order of two 
hundred to three hundred links for a flexible belt 1' having a developed 
length of about one meter. 
The formation of loop 2' employs procedures that may be known. Such 
procedures may be those used for the formation of conventional covered 
V-belts or raw-edged V-belts. 
In a variant that utilizes a "reversal", or "turning inside out" technique, 
a cylindrical sleeve of appropriate length is fabricated in a succession 
of layers. The first layer includes coating 18', having a low coefficient 
of friction. Such coating 18' may be made from a very high molecular 
weight polyethylene film or possibly ethylene polytetrafluoride. Elastomer 
compound base 13' may be located above and/or below traction layer 9'. The 
formation of traction layer 9' may be performed, for example, by using 
twisted aromatic polyamide fibers that have, preferably, been treated to 
ensure adherence with elastomer compound 13'. The layers may be reinforced 
by fabric or by short fibers before being arranged to form loop 2'. At 
this stage, loop 2' may be in the form of a cylindrical sleeve. Such a 
loop 2' is resistant to transversal compression. The elastomer compound 
base 13' and traction layer 9' thus formed is then vulcanized by 
pressurized heat treatment around an internal core. This process gives a 
smooth surface to coating 18'. Finally, the sleeve is cut into individual 
loops 2' that are then " turned inside out." 
The assembly of links 4' and/or 20' on loop 2' is, necessarily, a 
mechanized operation because of the high number of components employed to 
make a single belt 1'. Lateral staples 16' of links 4' and/or 20' are 
forced over large base area 17' and traction layer 9' of loop 2'. 
In the embodiment of the present invention that employs closable links 20', 
straps 21' are folded after assembly. The closing of straps 21' is made 
possible by the flexing of hinge 22'. Heat sealing or adhesive fastening 
of matching lugs 25' in cavities 24' may be performed by a continuous 
process, thereby making the assembly permanent. 
Irrespective of whether links 4' or links 20' are employed, the above 
formed assembly is covered by fabric 3' after the prior deposition of a 
layer of adhesive on the surfaces to which fabric 3' is to be joined, if 
such adhesive is deemed to be necessary. The edges of fabric 3' are either 
partly folded back, or are overlapped to ensure closing. This complete 
assembly of the flexible belt is then enclosed in a mold to press fabric 
3' in contact with the external surfaces of links 4' and 20', and bevels 
11'. An appropriate heat treatment ensures bonding of fabric 3' to links 
4' and/or 20', without damage to the previously vulcanized materials that 
form loop 2'. 
The composite belt 1' that forms a flexible transmission belt according to 
the present invention can be used in the same manner as a conventional 
V-belt or as a wide belt for a mechanical power transmission. Belt 1' of 
the present invention has the following advantages over the transmission 
belts of the prior art: 
1. The performance of belt 1' may be considered as a combination of the 
capabilities of thrust link transmissions that operate without lubrication 
and the capabilities of conventional V-belts; 
2. The reciprocal contact between the oblique walls of the links and the 
loop helps to ensure the centering and alignment of the links. 
3. The relative slip of the components experienced in thrust link 
transmissions is minimized by the mechanical adherence of the links 
against the deformable oblique walls of the loop; 
4. The resulting flexible belt combines the mechanical adherence of 
conventional V-belts with the transversal incompressibility of flexible 
elements with rigid links; 
5. The presence of the cover fabric, which is used for the mechanical 
adherence of the links against the flanges of the pulleys, forms an 
elastic connection between the links, thereby reducing the risk of 
vibration at annoying acoustical frequencies; 
6. The separation, due to alternating fatigue, of the components of the 
loop is minimized by an improved distribution of stresses over a surface 
that remains in permanent contact with the link; and 
7. The mass production of several sizes of links makes it possible to 
manufacture flexible elements in any desired original belt length, thereby 
making the production of such transmission belts, or elements, 
particularly economical. 
Without going beyond the context of the invention, a technician skilled in 
the art can combine all shape and size variations to ensure an efficient 
transmission by flexible elements between two or more grooved pulleys. 
In summary, one feature of the invention resides broadly in a transmission 
element for infinitely variable transmission, with transverse thrust links 
characterized by the fact that the endless core 2 is a V-belt with oblique 
walls 5 in contact with the interior surfaces 10 of the links in the shape 
of stirrups 1 or 15, surrounding said V-belt, their exterior oblique 
surfaces 11 forming the surface which comes in contact with the cheeks of 
the transmission pulleys. 
Another feature of the invention resides broadly in a transmission element 
for infinitely variable transmission characterized by the fact that the 
endless core 2 is formed by a V-belt with covered oblique walls 5. 
Yet another feature of the invention resides broadly in a transmission 
element for infinitely variable transmission characterized by the fact 
that the endless core 2 is formed by a V-belt with bare oblique walls 5. 
A further feature of the invention resides broadly in a transmission 
element characterized by the fact that the endless core 2 is provided on 
its exterior surface 6 with a coating 6a having a low coefficient of 
friction, on which links in the form of stirrups 1 or 15 are supported 
during the straight-line trajectory on the slack side. 
A yet further feature of the invention resides broadly in a transmission 
element characterized by the fact that the guide device for the links in 
the form of stirrups 1 or 15 is provided both by the existence of 
centering pins 13 and cavities 14 located near lateral staples 12 or 
cavities 19, and by the alignment of the interior surfaces 10 in contact 
against the oblique walls 5 of the endless core 2 constituted by a V-belt. 
Yet another further feature of the invention resides broadly in a 
transmission element for infinitely variable transmission characterized by 
the fact that the links in the form of stirrups are constituted by closed 
stirrups 15' having a strap 16 which encloses the endless core 2 by 
engagement of the matching lugs 20 in the cavities 19. 
An additional feature of the invention resides broadly in a transmission 
element for infinitely variable transmission characterized by the fact 
that the definitive closing of each of the closed stirrups 15 is done by 
heat-sealing or attachment by adhesive of the lugs 20 in the matching 
cavities 19. 
Patent publications such as French Patent Publication No. 2,437,531 which 
is assigned to Varitrac AG, and European Patent Publication Nos. 0,242,263 
and 0,395,227 which are both assigned to Hutchinson, each disclose belts 
with rigid transversal reinforcements elements. The reinforcement elements 
may be made of metal. The reinforcement elements cooperate together and 
also cooperate with a longitudinal traction armature. The reinforcement 
elements and the armature may be embedded in the elastomer base material 
of the belt. 
Numerous patent publications, in particular several assigned to Van Doorne, 
such as U.S. Pat. No. 3,720,113; French Patent Publication No. 2,089,587; 
and European Patent Publication Nos. 0,000,802, 0,014,013 and 0,014,492 
disclose solid belt assemblies that are mounted on a guide element. 
A variant of such belts employs reinforced plastic rigid riders, or 
staples, that act as thrust links and operate without lubrication. Such 
belts are disclosed in French Patent Publication Nos. 2,536,486, and 
2,527,723 and its Certificate of Continuation, French Patent Publication 
No. 2,536,487. All of these publications are assigned to Michelin. 
Additional variants of the belts described above are also disclosed in 
French Patent Publication No. 2,625,783 which is assigned to Caoutchouc 
Manufacture Et Plastiques. 
All, or substantially all, of the components and methods of the various 
embodiments may be used with at least one embodiment or all of the 
embodiments, if any, described herein. 
All of the patents, patent applications and publications recited herein, if 
any, are hereby incorporated by reference as if set forth in their 
entirety herein. 
The details in the patents, patent applications and publications may be 
considered to be incorporable, at applicants' option, into the claims 
during prosecution as further limitations in the claims to patentably 
distinguish any amended claims from any applied prior art. 
The invention as described hereinabove in the context of the preferred 
embodiments is not to be taken as limited to all of the provided details 
thereof, since modifications and variations thereof may be made without 
departing from the spirit and scope of the invention.