TRANSMISSION, TRANSVERSE BELT ELEMENT

Technica3L_ ield This invention relates to an improved endless power transmission belt construction for a continu¬

ously variable transmission, and to a transverse belt

element therefor as well as to methods of making the belt construction and the belt element.

Background_ Art

It is known to provide a belt construction for

a continuously variable transmission wherein the belt

construction comprises an endless flexible band means

and a plurality of belt elements carried by the band means in sliding relation therewith, each belt element having slot means receiving the band means therein, and having opposed faces disposed in compressed re¬ lation against adjacent faces of adjacent belt ele¬

ments. Such belt elements are formed from metallic

material. For example, see the ϋ. S. Patent to Doorne et al, No. 3,720,113; the U. S. Patent to Aberson,

No. 4,299,586; and the U.S. Patent to Vollers, No. 4,030,941.

While it is applicant's belief that no one has provided such a belt construction wherein all of the

belt elements are formed substantially solely from a high performance polymeric material that has high heat

resistance, high compressive modulus, high toughness, and high strength according to the teachings of this

invention, the U. S. Patent to Hattori et al, No. 4,338,081, has every other belt element between the

driving metal belt elements thereof formed as a non- driving belt element and formed of "non-metallic ma¬

terial having excellent compression resistance, such as synthetic resin, carbon graphite, synthetic resin

containing carbon graphite fibers, and hard rubber so

that the weight of the torque transmission belt can

be reduced". It should also be noted that this U. S, Patent No. 4,338,081, while describing that the main

belt elements are formed of tool steel, states

"Furthermore, the main blocks 7 can be made of materi¬

al other than tool steel if it has the sufficient

strenght and abrasion resistance required in torque transmitting means of this type."

It is also known to provide a belt construction for a continuously variable transmission and

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comprising an endless flexible band means and a plu¬ rality of belt elements carried by the band means in

sliding relation therewith, each belt element having slot means receiving the band means therein, and

having opposed faces disposed in compressed relation

against adjacent faces of adjacent belt elements.

Each belt element has opposed sides for respectively

engaging pulley faces of the transmission. The slot

means for each belt element defines a pair of slots

respectively interrupting the opposed sides thereof and being spaced from each other by a central stem

portion of the element. The pair of slots for each-

element receives parts of the band means therein, and respectively defines a pcir of shoulders engaging the parts of the band means, each shoulder of each belt element having an arcuate transverse crora surface provided with an apex that engages its respective part of the band maans. For example, see the afore¬

mentioned U. S. Patent to Vollers, .:o. 4,080,841,

wherein it appears in FIG. 3 hεreof that the apexes

of the surfaces 9 are each disposed in the center of its respective transverse shoulder.

It is one feature of this invention to provide

an improved belt construction for a continuously vari¬ able transmission, wherein all of the belt elements

are formed of polymeric material, which will allow for major weight reduction of the transmission system and

may also allow for higher belt speeds since centri-

fugally-generated tension would be reduced.

For example, it is believed according to the teachings of this invention that each belt element for the belt construction for a continuously variable transmission can be formed substantially solely from

a high performance polymeric material that has high heat resistance, high compressive modulus, high tou _β h- ness, and high strength.

In particular, one embodiment of this invention provides a belt construction for a continuously

variable transmission, the belt construction com¬

prising an endless flexible bend means, and a plu-

rality of belt elements carried by the band means in sliding relation therewith. ach belt element

has slot means receiving the band means therein,

and has opposed faces disposed in compressed

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relation against adjacent faces of adjacent belt ele¬

ments. Each belt element is formed substantially

solely from a high performance polymeric material

that has high heat resistance, high compressive modulus, high toughness, and high strength.

"While it is believed according to the teachings

of this invention that such a belt construction can be utilized in a conventional lubricated environment

for the continuously variable transmission, each belt element of this invention can be provided with a lubricating filler means therein, so that the con¬

tinuously variable transmission utilizing the belt construction of this invention would have the belt

elements thereof be self-lubricating, and would there-

by allow the transmission to run in an unlubricated

environment, such as in air, without undue wear on the belt elements, sheaves, or tensile bands.

It is another feature of this invention to pro¬ vide an improved belt construction for a continuously

variable transmission wherein each belt element tends to bias its respective part of the band means toward

its respective central stem rather than toward its

respective pulley face of the transmission.

In particular, it is believed according to the

teachings of this invention that if the band means can

be prevented from engaging against the pulley faces during the operation of the continuously variable

transmission, wear-out of the pulley faces by such

band means will be prevented.

Accordingly, it is believed that the apex of

each transverse, crown surface of the respective belt

element of this invention can be offset relative to

the center between its respective side and the central stem of that belt element to tend to bias its respec¬

tive part of the band means toward the central stem rather than toward its respective side.

For example, one embodiment of this invention provides a belt construction for a continuously vari¬ able transmission, the belt construction having an endless flexible band means, and a plurality of belt

elements carried by the band means in sliding relation

therewith, each belt element having slot means re-

ceiving the band means therein, and having opposed

faces disposed in compressed relation against adjacent faces of adjacent belt elements. Each belt element

also has opposed sides for respectively engaging

pulley faces of the transmission, the slot means for

each belt element defining a pair of slots respec¬

tively interrupting the opposed sides thereof and

being spaced from each other by a central stem por- tion of the belt element. The pair of slots for each

belt element receive parts of the band means therein

and respectively defining a pair of shoulders engag¬ ing the parts of the band means, each shoulder of each belt element having an arcuate transverse crown surface which is provided with an apex that engages

its respective part of the band means. The apex of each transverse crown surface of its respective belt

element is offset relative to the center between its respective side and its respective central stem to tend to bias its respective part of the band means

toward its respective central stem rather than toward its respective side.

Accordingly, it is an object of this invention to provide an improved belt construction for a con-

tinuously variable transmission, the belt construc¬

tion of this invention having one or more of the novel features of this invention as set forth above or hereinafter shown or described.

Another object of this invention is to provide

a method for making such a belt construction, the method of this invention having one or more of the

novel features of this invention as set forth above or hereinafter shown or described.

Another object of this invention is to provide an improved belt element for such a belt construction,

the belt element of this invention having one or more - of the novel features of this invention as set forth above or hereinafter shown or described.

Another object of this invention is to provide

an improved method of making such a belt element, the method of this invention having one or more of the

novel features of this invention as set forth above or hereinafter shown or described.

The features of the invention, and its techni¬

cal advantages, can be seen from the following de¬ scription of preferred embodiments, together with the

claims and the accompanying drawings, in which:

FIG. 1 is a schematic side view of a con¬ tinuously variable transmission means with parts in section, the transmission means including the im¬

proved belt construction of this invention; - ^■ FIG. 2 is an enlarged cross-sectional view

of a portion of the belt construction of FIG. 1;

FIG. 3 is a fragmentary perspective view

of part of -the belt construction of FIG. 2;

FIG. 4 is an enlarged front view of one of the transverse belt elements of the belt construction

of FIGS. 1-3 before the same is assembled to the flexible band means of the belt construction of FIGS. 1-3;

FIG. 5 is a side view of the belt element of FIG. 4; and

FIG. 6 is ^' a fragmentary view similar to FIG. 4 and illustrates the belt element when assem¬ bled to part of the band means of the belt

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construction of FIGS. 1-3.

Be t_ _. Modas_for_ Carryin _Cut_the _Invention

While the various features of this invention are hereinafter illustrated and described as pro-

viding a belt construction which is particularly

adapted to be utilized for continuously variable

transmission purposes, it is to be understood that .

the various features of this invention can be util¬ ized singly or In any combination thereto to provide

a.belt construction for other uses as desired, such

as for driving accessories for an engine of a trans¬ portation vehicle. Also, such belt construction

could be utilized in place of other conventional belts, as desired. Therefore, this invention is not to be limited

to only the embodiment illustrated in the drawings,

because the drawings are merely utilized to illustrate one of the wide variety of uses of this invention.

Referring now to FIG. 1, a conventional contin- uously variable transmission arrangement is generally

indicated by the reference numeral 20 and comprises a

pair of rotatable pulleys 21 a d 22, one of which is

to be driven by the other thereof by means of an

endless power transmission belt construction of this

invention; such belt construction is generally in¬

dicated by the reference numeral 23 and operates, in

general, in a manner conventional in the art, the pulleys 21 and 22 having variable diameters in a

manner well known in the art. A continuously variable transmission is provided by the arrangement 20 in a manner well known in the art and as set forth in the

aforementioned four U. S. Patents, Mos. 3,720,113; 4,080,341; 4,299,536; and 4,338,081; and the United

Kingdom Patent application No. G3 2,088,018A, whereby

these four patents and patent application are being incorporated into this disclosure by this reference thereto. Since the operation of a continuously variable

power transmission arrangement is well known in the

art, a further description of the arrangement 20 need

not be set forth, since the features of this invention

will be directed to the endless power transmission belt construction 23 which will be hereinafter de¬ scribed.

However, it is to be understood that the ar¬

rangement 20 could operate in an externally lubricated

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environment, as is conventional with all metal belt constructions for continuously variable transmission

systems, or can operated in a non-lubricated environ¬

ment as will be apparent hereinafter. The endless belt construction 23 of this in¬ vention comprises an endless flexible band means or

tensile means, generally indicated by the reference numeral 24, and a plurality of transverse belt ele¬ ments 25 which are carried by the carrier means or band means 24 in a manner hereinafter set forth.

The flexible band means 24 actually comprises a pair of band means 24A and 24B which are disposed

and held in spaced apart parallel relation by the belt elements 25 in a manner hereinafter set forth.

Each band means 24A or 242 is formed from a single

endless element or a plurality of endless elements as

is conventional in continuously variable transmission systems; the band means 24A and 243 are merely illus¬

trated schematically as being formed from a single layer of metallic material, with the understanding

that the same can be formed from a plurality of layers

in a conventional manner, and of other materials, as desired.

Each transverse belt element 25 of this inven¬

tion is substantially trapezoidal in configuration when viewed in the manner illustrated in FIG. 4, and

has opposed front and rear faces 26 and 27, as well as

opposed side faces 28 and 29. The side faces 28 and

29 are angled relative to each other to give a sub¬ stantially "V" shape to each belt element 25 and to engage the angled pulley faces 21' and 22' of the pulleys 21 and 22 in a conventional manner.

- Each belt element 25 also has a top face or side

30, and a bottom face or side 31, which are disposed

substantially parallel to each other and are substan¬

tially flat, as illustrated. If desired, the top sur¬ face or face 30 can have angled opposed ends 30' as illus rated.

The opposed front and rear faces 26 and 27 of each belt element 25 have upper portions 26 ^? and 27'

that are disposed substantially parallel to each other, and lower portions 26" and 27" which respectively

taper toward each other as they approach the bottom surface 31.

Each side face 28 and 29 is interrupted by a

slot 32 which is disposed spaced from the other slot

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32 so as to define a central stem portion 33 of the belt element 25 therebetween. Each slot 32 defines

a lower shoulder 34 that will engage part of the in¬

side surface of the band means 24, as will be appatent 5 hereinafter. Each slot 32 also defines an upper shoulder 35 which is normally spaced from the top sur¬

face of the band means 24. Each shoulder 34 of the

belt element 25 defines a transverse crown surface 36 which Is uniquely constructed so that the same has the

10 apex 37 thereof disposed closely adjacent the side 28 or 29 of the respective slot 32 so as to be offset relative to the center of the transverse crown surface 36 between the respective side 23 or 29 and the ad¬

jacent surface 38 of the central stem 32 for a purpose

15 hereinafter set forth. In one embodiment of the belt element 25 of this invention, the apex or peak 37 of

the crown surface 36 of each shoulder 34 Is located

approximately directly beneath the cuter end of its

___ respective top surface 30', so that approximately 2/3

20 of the length of the crown surface 36 extends from the

apex 37 to the adjacent surface 38 of the central stem

33 of that belt element, and approximately V3 of the length of the crown surface 36 extends from the apex

, ._, - _ ... /

37 to the adjacent end face 28 or 29.

Each shoulder 34 of the belt element 25 also de¬

fines a longitudinal crown surface 39 as illustrated

in FIG. 5,with the apex 40 of the surface 39 being disposed substantially in the center between the op¬

posed front and rear faces 26 and 27 of the belt ele¬

ment 25 as illustrated.

The compression pitch line for each belt element

25 is chosen according to the teachings of this in- vention in such a way that the required elongation of

the band means 24, when all of the elements 25 are carried thereby in the manner illustrated in FIGS. 1

and 2, will be less than 10% of the yield elongation of the band means 24, whereby it can be seen that in

the completed belt construction 23, the band means 24

will be under tension, while each belt element 25 will be under compression between adjacent faces 26 and 27

of the adjacent elements 25 throughout the entire length of the band means 24.

When the elements 25 are assembled onto the band parts 24A and 24B as illustrated in FIG. 3, by merely

having the band parts 24A and 24B inserted into the

slots 32, it can be seen that the apexes 37 of the

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transverse crown surfaces 36 of each element 25, as illustrated in FIG. 6, tend to bias the particular

band part 24A or 24B toward the central stem 33 of the element 25 rather than toward the respective side 28 or 29 thereof, so that the tendency of the band

means 24A or 24B to engage against the pulley faces 21' and 22' during the operation of the system 20 is less likely, and therefore the surfaces 21* and 22'

will not tend to wear out as would be the case if such surfaces 21' and 22' were being utilized as the means for confining the band means 24A and 24B in the slots 32 as in the prior known continuously variable

transmission arrangements.

While the band sections 24A and 24B are resec- tively illustrated as having the outer end edges 24A' and 24B' disposed short of the surfaces 2S and 29 when

the elements 25 are assembled thereon in the manner

illustrated in FIGS. 3 and 6, it is to be understood that the outer end edges 2 ' and 2'.B' of__b_and__jrieans____

24A and 24B can extend closely adjacent the surfaces 28 and 29 while still being disposed closely adjacent the central stem portion 33 as illustrated.

In any event, it can be seen that it is a rela¬

tively simple method of this invention to form the belt elements 25 into the configuration illustrated,

so that when the same are assembled to, and are oper- ating with, the band means 24 in the system 20, the

movement of the elements 25 relative to the band means 24 as in conventional continuously variable trans¬

mission systems can take place, and the apexes 37 of the transverse crown surfaces 36 of the shoulders 34

of each belt element 25 will tend to bias the band sections 24A and 243 inwardly toward the central stem portion 33 , for the reasons previously set forth, and

thus away from the pulley faces 21' and 22'.

While it is believed that the elements 25 can be made of any suitable material, as previously stated,

it is another feature of this invention to form the

belt elements 25 for the belt construction 23 substan¬ tially solely from a high performance polymeric mate¬ rial that has high heat resistance, high compression modulus, high toughness, and high strength.

For example, such polymeric material can be se¬

lected from the group of a polyamide-imide, polyimide, polyphenylane sulfide, nylon - 6 or 6/6 or 6/10,

aromatic polyamide, polyvinylidene fluoride, poly-

etheretherketone, polyetherimide, perfluoroalkoxy- modified tetrafluoroethylene, polytetrafluoroethylene, and polyethersulfone, as well as other polymeric ma-

terials that meet the above characteristics. For example, the above mentioned polyamide-imide can be

purchased from Amoco Chemicals Corporation, P, 0. Box 8640A, Chicago, Illinois, 60630, under the trademark

"T0RL0N". - ^• In addition, while certain of the above poly¬

meric materials are self-lubricating, such polymeric materials can be made self-lubricating or further

self-lubricating by being filled with a lubricating filler means. For example, a dry lubricant, such as

polytetrafluoroethylene, molybdenum disulfide, graphite,

or other suitable lubricating filler means can be utilized.

In addition, the polymeric material could be further strengthened by having strengthening or re-

inforcing filler means disposed therein, such as

glass, carbon, etc., and the filler means could be in the form of fibers, powder, etc.

In any event, by providing the aforementioned

self-lubricating polymeric material, it is believed

according to the teachings of this invention that when the belt elements 25 are utilized with the band

means 24 in the manner previously set forth, the transmission means 20 need not be operating in a lu¬

bricating environment. For example, the transmission

means 20 may operate in air, whereby the self-lubri¬ cating features of the belt elements 25 will prevent

wear and galling of the interacting surfaces, especial¬

ly between the elements 25 and the contacting sheave

faces 21' and 22' ₀

Of course, the self-lubricating polymeric mate¬ rial previously set forth is not limited to an unlu-

bricated system, because even in a lubricated environ¬

ment, the self-lubrica ing polymeric material would

provide protection for the system if an occasional

lubricant-starved environmental condition should exist. Further, such materials would also allow the use of water base hydraulic fluids or glycol-based coolants instead of petroleum-based fluids as required with all metal belt constructions.

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It is also believed that the use of the afore¬ mentioned polymeric materials for the elements 25 will allow major weight reduction of the system 20 over the previously known metallic systems, and may also allow higher belt speeds, since centrifugally- generated tension would be reduced. In addition, it

might be found that failure-associated hazards are

reduced.

Further, adjacent belt elements 25 could each

be formed of a different polymeric material for im¬

proved performance characteristics therebetween, as desired.

In any event, it can be seen that it is a re¬

latively simple method of this invention to form the belt elements 25 of the aforementioned polymeric ma¬

terial, such as by melding the polymeric material into the desired configuration, whether the desired con¬ figuration is as illustrated in FIC. 4, or is any

other suitable configuration. It is believed according

to the teachings of this invention that before this

invention there has not been a belt construction for

a continuously variable transmission wherein all of

the belt elements thereof are formed substantially

solely from a high performance polymeric material that has high heat resistance, high compressive modulus,

high toughness, and high strength, whereby the system

20 will operate in the manner previously set forth.

Also, it is to be understood that the band means

24 of the belt construction 23 of this invention can

have polymeric material, similar to the polymeric ma¬ terial of the elements 25, forming at least a part

thereof, such as by a coating on the surfaces thereof, that would improve the performance of the action not

only between the layers of the band means 24, but

also between the band means 24 and the elements 25. Of course, the polymeric material of its band means 24

could be a different material from the material of the elements 25 in order to have unique performance characteristics.

Accordingly, it can be seen that this invention

not only provides an improved belt construction for a

continuously variable transmission, and method of

making the same, but also this invention provides an

improved belt element for such a belt construction, and a method of making such a belt element.

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While the forms and method steps of this inven¬ tion now preferred have been illustrated and described

as required, it is to be understood that other forms

and method steps can be utilized and still fall with- in the scope of the appended claims.