ENDLESS POWER TRANSMISSION V-BELT CONSTRUCTION AND METHOD OF MAKING THE SAME

Abstract: The belt construction is formed mainly of polymeric material, and has rounded top and bottom teeth respectively extending along the length of the top and bottom surfaces of the belt construction, the belt construction comprising a tension section (29) having the top surface (30), a compression section (31) having the bottom surface (32), and a load-carrying section (33) disposed intermediate the tension section and the compression section. The bottom to top tooth pitch ratio (45 to 44) of the belt construction (28) is approximately 1.40, and the bottom to top tooth depth ratio (47 to 46) thereof is approximately 1.77, while the belt thickness (42) to flex thickness (43) ratio thereof is approximately 3.98.

Description: ENDLESS POWER TRANSMISSION V-BELT CONSTRUCTION AND METHOD OF MAKING .THE SAME Technical Field This invention relates to an improved endless power transmission V-belt construction, as well as to a method of making such a belt construction. Background Art It is known in the art to provide an endless power transmission V-belt construction formed mainly of poly- meric material and having rounded top and bottom teeth respectively extending along the length of the top and bottom surfaces of the belt construction, the belt con¬ struction comprising a tension section having the top surface, a compression section having the bottom surface, and a load-carrying section disposed intermediate the tension section and the compression section. For example, see the following two United States Patents: (1) TJ. S. Patent No. 1,890,080 - Freedlander (2) ;U. S. Patent No..3,988,941 - Smith It appears that the endless power transmission V- belts of items (1) and (2) above each has the top and bottom rounded teeth thereof formed of substantially the same cross-sectional configuration. Disclosure of the Invention It is one feature of this invention to provide an improved endless power transmission V-belt construction that is particularly adapted for continuously, variable transmission use for transportation vehicles or the like. In particular, it is well known that continuously variable transmission V-belt constructions are each or¬ dinarily constructed with a large aspect ratio (ratio of top width to thickness), usually between . 2.0 and 4.0, in order to provide the greatest possible speed ratio. The top width of the belt construction is determined by the speed ratio and the tension required to transmit power, while the thickness is determined by the need for crosswise support and is constrained by the minimum di¬ ameter required by the speed ratio and the required ten¬ sion. These considerations are especially critical in - transportation vehicle drives which are characterized by short belt lengths which allow insufficient cooling of the belt constructions on each revolution thereof, . Accordingly, the belt construction must be thick enough . to prevent inward .collapse, or excessive crosswise flex .(dishing) .- and yet thin enough to flex over the minimum diameter required by he drive. V-belt constructions are commonly toothed, notched, or corrugated to provide the required flexibility while maintaining enough -thickness for crosswise support. Teeth also increase the heat transfer rate by increasing surface area and air flow around the belt, with round - teeth providing the shortest heat flow path to the out¬ side of the belt construction from the center of each tooth. In certain belt construction applications, greater thickness is required to prevent collapse than can be achieved with a single tooth construction, and therefore in such cases the V-belt constructions are - toothed both on the tops and bottoms thereof. Therefore, it was found according to the teachings of this invention that a V-belt construction of the double rounded tooth ' type allows the maximum total belt construction thickness to be used for τnaxiτm.πτι crosswise support while providing the π * πτ -m-i-i-m "flex thickness" (root plane of top tooth to root plane of. bottom tooth) which could be utilized for continuously variable trans¬ mission purposes. In particular, one embodiment of this invention pro ¬ vides an endless power transmission V-belt construction OMPI formed mainly of polymeric material and having rounded to and bottom teeth respectively extending along the length of the top and bottom surfaces of the belt construction, the belt construction comprising a tension section hav- ing the top surface, a compression section having the bot tom surface, and a load-carrying section disposed inter¬ mediate the tension section and the compression section. The bottom to top tooth pitch ratio of the belt construc¬ tion is approximately . 1.40, and the bottom to top tooth depth ratio thereof is approximately .1.77, while the belt thickness to flex thickness ratio is approximately 3.98. Accordingly, it is an object of this invention to provide an improved endless power transmission V-belt con¬ struction having one or more of the novel features of thi invention as set forth above or hereinafter shown or de¬ scribed. Another object of this invention is to provide a method of making such an endless power, transmission V- belt construction, the method of this invention having one or more of the novel eatures of this invention as set forth above or hereinafter shown or described. Brief Description o the Drawing The eatures of the invention, and its technical ad- vantages, can be seen from the following description of a preferred embodiment together with the claims and the ac¬ companying drawing, in which: Fig. 1 is a schematic side view illustrating a typ¬ ical continuously variable transmission unit; Fig. 2 is a fragmentary perspective view, partially in cross section, of the improved endless power trans¬ mission V-belt construction of this invention; and Fig..3 is an enlarged fragmentary side view of the belt construction of Fig. 2. Best Mode for C ' arryin'g Out -the Invention While the various features of this invention are hereinafter illustrated and described as being particu¬ larly adapted to provide an endless power transmission V- belt construction for continuously, variable transi OMPI A -. "WIPO purposes, it is to be understood that the various features of this invention can also be utilized singly or in various combinations thereof, to provide belt con¬ structions for other purposes. Therefore, this invention is not to be limited to only the embodiment illustrated in the drawing, be¬ cause the drawing is merely utilized to illustrate one of the wide variety of uses of this invention. Referrin ' now to Fig. 1, a typical continuously variable transmission unit for a transportation vehicle or the like is generally indicated by the reference nu¬ meral 20 and comprises a pair of adjustable sheave drive and driven pulleys 21 and 22 which are respectively ro¬ tatably mounted by means of drive and driven shafts 23 and 24. An endless power transmission V-belt construe- tion 25 is drivenly and drivingly disposed around the pulleys 21 and 22, which respectively can have the sheaves thereof adjusted in a manner well known in the art to have the belt construction 25 be looped between maximum and πrinimtTm diameters as respectively repre¬ sented, by the arrows 26 and 27 in Fig. 1 in order to provide a continuously, variable drive in a manner well known in the art. As previously stated, in order for. the unit 20 to provide the greatest possible speed ratio, the V-belt construction 25 is ordinarily constructed with a large aspect ratio (ratio of top width to thickness), such as between 2.0 and . 4.0. Such an endless power transmission V-belt construc- tion, which is generally indicated by the reference numeral 28 in Figs. 2 and 3, is provided by this inven— tion and will now be described. As illustrated in Figs. 2 and 3, the endless power transmission V-belt construction 28 of this invention comprises: a tension section 29 that defines a top surface 30 of the belt construction 28; a compression section 31 that defines a bottom surface 32 of the belt construction 28; and a load-carrying or neutral axis section 33 disposed intermediate the tension section 29 and the compression section 31 in a conventional manne The load-carrying section 33 comprises a top cushion o layer 34 and a bottom cushion or layer 35, with a load- carrying cord 36 helically wound therebetween in a man¬ ner well known in the belt construction art. The belt sections 29, 31 and 33, and the cord 36, are formed mainly of polymeric material. Furthermore, if desired, at least one of the tension section 29 and the compression section 31 can be fiber loaded (not shown) in a manner well-known in the art. . Also, if de¬ sired, one or more fabric layers, such as fabric layer 37 in Figs. 2 and 3,. can be disposed on at least one of the top and bottom surfaces.30 and 32 in a manner well known in the art. While any suitable polymeric material can be uti¬ lized for the sections 29,.31 and 33, the same can com¬ prise mainly neoprene with conventional fillers and binders as is. conventional in the belt art. The tension section 29 of the belt construction 28 is formed with a plurality of rounded teeth 38 that ex¬ tend substantially transverse to the longitudinal axis of the belt construction 28, are substantially uniform to each other, and extend along the entire length of the top surface 30 thereof as illustrated, the teeth 38 sometimes being referred to as cogs. Similarly, the compression section 31 of the belt construction 28 has a plurality of bottom teeth.39 formed therein that extend substantially transverse to the longitudinal axis of the belt construction 28, are substantially uniform to each other, and extend along the entire length of the bottom surface.32 of the belt construction 28 as illustrated, the teeth 39 also sometimes being referred to as cogs. The belt construction 28 of this invention can be made in any manner known in the art for producing double toothed belts, sometimes referred to as double cogged belts, such as by forming the bottom teeth as set forth in U.S. Patents 1,611,829 3,464,875 or 4,106,966 (which three. U.S. patents are being incorporated into this disclosure by. this reference thereto) , and by form— ing the top teeth, as set forth in U.S. Patent No. 4,106,966. However, by. using a preformed top teethed pad or by using a toothed matrix with a collapsible curing jacket, whereby the resulting belt construction 28 has opposed uncovered driving side edges 40, such as cut side edges or plate finished side edges, that cooperate with the top and bottom surfaces.30 and 32 to define the conventional trapezoidal cross-sectional configuration as illustrated in Fig.- 2, the belt construction 28 of this invention is formed so-'that the aspect ratio thereof as defined by the ratio of the top width of the belt con¬ struction 28 C -i ca ed by the reference, numeral 41 in Fig. 2) to the belt thickness Ci^-dicated by the reference numeral 42 in Fig. 3), is between 2.0 and 4.0 in order to provide a variable speed. V-belt construction. In particular, it was found according to the teach¬ ings of this invention that when the top width 41 of the belt construction 28 is approximately land 5/8 inches, and the belt thickness 42 is approximately 0.750 of an inch, the top and bottom teeth 38 and 39 should have the following pitch, ooth depth, tooth tip radii and root radii when considering a substantially straight section thereof, and the following flex thickness in order to •comprise the unique endless power, transmission V-belt construction of this invention: namely, the bottom to top tooth pitch ratio is approximately 1.40, the bottom to top tooth depth, ratio is approximately 1.77, and the belt thickness to flex thickness ratio is approximately :3.98. For example, the flex thickness of the particular belt construction 28 of this invention is represented by the reference numeral 43 in Fig. 3, and is approximately 0.188 of an inch. • The pitch of the top teeth 38 of the belt construc¬ tion 28 of this invention is represented by the reference numeral 44 in Fig. 3, and is approximately 0.3908 of an inch, while the pitch of the bottom teeth.39 is repre¬ sented bythe reference numeral 45 in Fig. 3, and is ap¬ proximately .0.547 of an inch. The root depth of the top teeth 38 of the belt con¬ struction 28 of this invention is represented by the reference numeral 46 in Fi . 3, and is approximately 0.203 of an inch, while the root depth of the bottom teeth 39 is represented by the reference numeral 47 in F g:.3, and is approximately 0.359 of an inch. The radius for defining the rounded tips of the top teeth.38 of the belt construction 28 of this invention is represented by radius arrow 48 in Fig. 3, and is ap¬ proximately 0.141 of an inch, while the tooth tip radius of the bottom teeth.39 is represented by. the radius arrow 49 in Fig. 3, and is approximately 0.156 of an inch. The root radius of the top teeth 38 of the belt construction 28 of this invention is indicated by the radius arrow 50 in Fig. 3, and is approximately . 0.047 of an inch, while the root radius of the bottom teeth 39 is indicated by the radius arrow 51 in Fig..3, and is ap- proximately 0.078 of an inch. While such a belt construction 28 of this invention can have any suitable length, it has been found that cer¬ tain continuously variable transmission units 20 for transportation vehicles require belt lengths from ap- proximately 30 inches to approximately 65 inches, and re¬ quire the belt to conform to minimum and maximum di¬ ameters 27 and 26 of approximately 3 inches and 9 inches. It has been found that the belt construction 28 of this invention having the dimensions previously set forth is suitable for such continuously variable trans¬ mission units 20. Therefore, it can be seen that it is a relatively simple method of this invention to form the belt con¬ struction 28 by conventional methods to have the top and bottom teeth 38 and 39 thereof so arranged in relation to the belt thickness 42 and flex thickness 43 to pro¬ vide a bottom to top tooth pitch ratio of approximately 1.40, a bottom to top tooth depth ratio of approximately 1.77, a belt thickness to flex thickness ratio of ap¬ proximately 3.98, and an aspect ratio of approximately 2.16. - Accordingly, it can be seen that this invention not only provides an improved endless power transmission V- belt construction, but also this invention provides an improved method of making such a belt construction. While the form and method of this invention now pre¬ ferred have been illustrated and described as required by the Patent Statute, it is to be understood that other forms and method steps can be utilized and still fall within the scope of the appended claims.

Claims: CLAIMS :- ' 1. In an endless power transmission V-belt con¬ struction formed mainly of polymeric material and having rounded top and bottom teeth respectively extending along the length of the top and bottom surfaces of said belt construction, said belt construction comprising a tension section having said top surface, a compression section having said bottom surface, and a load-carrying section disposed intermediate said tension section and said compression section, the improvement characterized in that the bottom to top tooth pitch ratio (45 to 44) is approximately .1.40, the bottom to top tooth depth ratio (47 to 46) is approximately 1.77, and the belt thickness (42) to flex thickness (43) ratio is approx¬ imately 3.98. 2. A belt construction as set forth in claim.1, characterized in that the top width (41) to belt thick¬ ness (42) ratio range is approximately 2-4. 3. A belt construction as set forth in claim 1, characterized in that said belt thickness (42) is ap¬ proximately 0.750 of an inch, and said flex thickness (43) is approximately 0.188 of an inch. 4. A belt construction as set forth in claim 3, characterized in that the pitch (44) of said top teeth (38) is approximately 0.3908 of an inch, and the pitch (45) of said bottom teeth (39) is approximately .0.547 of an inch. 5 . A belt construction as set forth in claim 4, characterized in that the tooth depth (46) of said top teeth (38) is approximately 0.203 of an inch, and the tooth depth (47) of said bottom teeth (39) is approxi- ately 0.359 of an inch. 6. A belt construction as set forth in claim 5 , characterized in that, each top tooth (38) has a tooth tip radius (48) of approximately 0.141 of an inch, and each bottom tooth (39) has a tooth tip radius (49) of ap¬ proximately 0.156 of an inch. . 7. A belt construction as set forth in claim 6, characterized in that the roots of said top teeth (38) each has a radius (50) of approximately .0.047 of an inch, and the roots of said bottom teeth (39) each has a radius (51) of approximately 0.078 of an inch. 8. A belt construction as set forth in claim 7, characterized in that the top width (41) of said belt construction (28) is approximately 1.625 inches. 9. A belt construction as set forth in claim 1, characterized in that at least one of said tension sec¬ tion (29) and said compression section (31) has reinforc¬ ing fiber means therein. 10. A belt construction as set forth in claim 1, characterized byat least one layer of fabric means (37) on at least one of. said top surface (30) and said bottom surface .(32) . OMPI

Inventors: FOLEY MARK P, HOLLAWAY GERARD C, LEWIS JAMES A, MIRANTI JOSEPH P JR, OLIVER LARRY R, STANDLEY PAUL M, FOLEY, MARK, P., HOLLAWAY, GERARD, C., LEWIS, JAMES, A., MIRANTI, JOSEPH, P., JR., OLIVER, LARRY, R., STANDLEY, PAUL, M.
Applicants: DAYCO CORP, DAYCO CORPORATION
Application year: 1983
Main classification: F16G1
IPC codes: B29D29, B32B3, F16G5