Belt mechanism of continuously variable transmission for bicycle

Abstract

The present invention relates to a belt mechanism of a continuously variable transmission for a bicycle, comprising: a driving pulley and a driven pulley comprising a pair of pulleys that can approach and separate from each other in the direction of a rotation axis; and a V-belt wound between the drive pulley and the driven pulley, in which the V-belt has an LT coefficient of 8-12 with respect to the drive pulley under use conditions in which the maximum torque is achieved in a state in which the speed is shifted to the lowest speed side, and in which the belt lateral rigidity in a measurement test of variation in the exposure height of the V-belt is 1500-2500 N / mm.

Description

Technical Field

[0001] The present invention relates to a belt mechanism provided in a continuously variable transmission for a bicycle. Background Art

[0002] V-belts that transmit power through friction transmission include raw-edge types (raw-edge V-belts) in which the friction transmission surface (V-shaped side) has an exposed rubber layer, and wrapped types (wrapped V-belts) in which the friction transmission surface is covered with a cover cloth. They are used according to the surface properties of the friction transmission surface (friction coefficient between the rubber layer and the cover cloth) and the purpose of use.

[0003] In addition, among the cut-edge type belts, in addition to the cut-edge V-belts without cogs, there are also cut-edge toothed V-belts with cogs only on the lower surface (inner circumference) of the belt to improve the bending properties, and cut-edge toothed V-belts with cogs on both the lower surface (inner circumference) and upper surface (outer circumference) of the belt to improve the bending properties (cut-edge toothed V-belts).

[0004] Cut-edge V-belts and cut-edge toothed V-belts are mainly used for driving general industrial machinery, agricultural machinery, and auxiliary machine driving in automobile engines. In addition, as other uses, there are cut-edge toothed V-belts called variable speed belts used in belt-type continuously variable transmissions (CVT: Continuously Variable Transmission) for motorcycles, snowmobiles, four-wheeled small vehicles, etc. Hereinafter, the cut-edge toothed V-belt is referred to as a V-belt (or variable speed belt).

[0005] like Figure 1 As shown, the belt mechanism 30 of the belt-type continuously variable transmission is a mechanism for winding a V-belt 1 around a driving pulley 31 and a driven pulley 32 to change the speed ratio steplessly. Each pulley 31, 32 has a fixed pulley 31a, 32a that restricts or fixes the movement in the axial direction and a movable pulley 31b, 32b that can move in the axial direction, and the inner circumferential wall of the fixed pulley 31a, 32a and the inner circumferential wall of the movable pulley 31b, 32b form a V-groove-shaped inclined opposite surface. The driving pulley 31 and the driven pulley 32 have a structure that can continuously change the width of the V-groove of the driving pulley 31 and the driven pulley 32 formed by these fixed pulleys 31a, 32a and movable pulleys 31b, 32b. The two end surfaces of the V-belt 1 in the width direction are formed by tapered surfaces that are inclined in accordance with the inclined opposite surfaces of the V-grooves of the driving pulley 31 and the driven pulley 32, and are inserted into any vertical position of the opposite surfaces of the V-grooves according to the width of the changed V-grooves. For example, when the width of the V-grooves of the driving pulley 31 is narrowed and the width of the V-grooves of the driven pulley 32 is widened, the V-grooves of the driven pulley 32 are increased. Figure 1 The state shown in (a) is changed to Figure 1In the state shown in (b), the V-belt 1 moves upward in the V groove on the driving pulley 31 side and moves downward in the V groove on the driven pulley 32 side, and the diameter of the belt around the driving pulley 31 and the driven pulley 32 changes continuously, so that the speed ratio can be changed steplessly.

[0006] A lot of technologies related to the belt mechanism (especially V-belt) of the belt-type continuously variable transmission mounted on the above-mentioned motorcycle (scooter) have been disclosed to date, but there are few examples (for example, Patent Document 1 and Patent Document 2) proposed to date regarding the technology of the belt mechanism of the belt-type continuously variable transmission mounted on a bicycle (including a bicycle with an auxiliary power source such as an electric motor).

[0007] For example, the belt mechanism (for example, Figure 2 A) Although detailed description is omitted, it includes: a driving pulley (input unit 1100) connected to the rotating shaft of a crank equipped with a pedal at the front end via a gear mechanism (input amplifying unit 7510: refer to FIG. 13B) and the like; a driven pulley (output unit 1300) connected to the driving shaft of the rear wheel via a gear mechanism (output amplifying unit 7400: refer to FIG. 13B) and a chain; and a V-belt (transmission unit 1200) wound around the driving pulley and the driven pulley. The gear mechanism attached to the belt mechanism maintains the driving pulley and the driven pulley in a higher speed state in order to facilitate the stable operation of the continuously variable transmission by the belt mechanism. It is not necessary in the belt-type continuously variable transmission of a motorcycle (scooter) in which the rotation speed of the crankshaft is maintained significantly higher than that of a bicycle (for example, about 60 to 80 rpm), and it can be said that it is a structure dedicated to bicycle use.

[0008] Thus, a belt-type continuously variable transmission for bicycles has only recently been proposed as a product: by having a belt mechanism (a structure of a driving pulley, a driven pulley, and a V-belt) described in Patent Document 2 and other mechanisms (a speed-increasing gear mechanism, etc.) associated therewith, it has a function of efficiently converting the pedal force into the thrust of the bicycle (for example, the rotation speed of the pedals can be maintained as constant as possible regardless of the speed of the bicycle). However, in the existing documents such as Patent Document 1 and Patent Document 2, only a continuously variable transmission for bicycles using a belt mechanism (a structure of a driving pulley, a driven pulley, and a V-belt) is described, and no detailed design technology related to the belt mechanism (especially the V-belt) suitable for the transmission is studied.

[0009] Prior art literature Patent Literature Patent Document 1: Japanese Patent Application Laid-Open No. 5-278668 Patent Document 2: Japanese Patent Application No. 2019-503923 Summary of the invention

[0010] Problems to be solved by the invention

[0011] Therefore, regarding the belt mechanism (particularly a V-belt) included in the continuously variable transmission for bicycles, detailed design of the belt mechanism applicable to the use conditions as the premise thereof has been studied, and as a result, the following problems have arisen.

[0012] (Usage conditions assumed when a continuously variable transmission is used in a bicycle)

[0013] ・Condition 1

[0014] Compared with a small motorcycle (displacement 50 to 125cc), the space and weight constraints of a belt-type continuously variable transmission mounted on a bicycle are large, so it is required not only to ensure the above functions, but also to be sufficiently compact (small and light) as described in Patent Document 2 (reference number 8000 in FIG. 15 ). Therefore, the various structures of the belt mechanism of the transmission are also subject to the following restrictions.

[0015] (1) Make the pulley (minimum pitch diameter) small

[0016] For example, in the case of a small motorcycle, the minimum pitch circle diameter is about 40 to 55 mm, whereas the diameter is limited to a range close to the lower limit of about 40 to 45 mm.

[0017] (2) To wind the belt around the small-diameter pulley in (1), the belt thickness is reduced.

[0018] For example, in the case of a scooter, the belt thickness is about 7 mm to 12 mm, whereas the belt thickness is limited to a lower limit range of about 7 to 9 mm.

[0019] ・Condition 2

[0020] In the case of a bicycle, the main force is the pedaling force. Compared with a scooter, the pedal speed is low (for example, around 60 to 80 rpm). Even if the speed is increased by a speed-increasing gear mechanism, it is still around 2000 rpm. Therefore, the maximum torque (the maximum value of the torque input to the drive shaft of the speed-changing belt mechanism) is relatively large (for example, a scooter is around 3 to 12 Nm, while a bicycle is relatively large, around 10 Nm).

[0021] That is, in the speed change belt mechanism of the bicycle belt type continuously variable transmission, under the speed change condition where the pitch diameter of the drive pulley (refer to the definition described below) is the smallest (for example, about 40 to 45 mm), Figure 2 In the pulley layout of a small motorcycle, the pulley pitch diameter (minimum pitch diameter) is small relative to the maximum torque and the belt thickness is thin.

[0022] (Topics to be adapted to the usage conditions)

[0023] Therefore, under this speed change condition, compared with a small motorcycle, the winding angle (contact angle) and winding length of the belt to the drive pulley become smaller, and the contact area (area of ​​the friction transmission surface) between the drive pulley (V-groove) and the belt (V-shaped side) becomes significantly smaller, resulting in a strict friction transmission state, that is, a state in which slippage is very likely to occur between the drive pulley and the belt.

[0024] In other words, in the speed change belt mechanism of the belt-type continuously variable transmission for bicycles, if the LT (Limit Torque) coefficient defined in the formula described later, which is an indicator (substitute characteristic) indicating the ease of belt slippage, is too large, it means that the friction transmission capacity is insufficient under the speed change condition where the pitch diameter of the drive pulley is the smallest, and slippage between the drive pulley and the belt is extremely easily induced under such harsh usage conditions (pulley layout, load).

[0025] For example, the LT coefficient for a scooter is about 4 to 8, whereas the LT coefficient for a bicycle is about 8 to 12, which exceeds the actual range for a scooter.

[0026] Therefore, an object of the present invention is to provide a belt mechanism for a bicycle continuously variable transmission which is compact and can suppress slippage and ensure necessary transmission force even under usage conditions where the LT coefficient is too large.

[0027] Technical solutions to solve problems

[0028] The present invention is a belt mechanism for a bicycle continuously variable transmission, comprising: a driving pulley and a driven pulley, which are composed of a pair of pulleys that can freely approach and separate in the direction of the rotation axis; and a V-belt that is hung between the driving pulley and the driven pulley, characterized in that: Under the use condition of maximum torque in a state of shifting to the lowest speed side, the LT coefficient of the V-belt with respect to the driving pulley is in the range of 8 to 12, and the belt lateral rigidity in a ride-out change measurement test of the V-belt is in the range of 1500 to 2500 N / mm.

[0029] According to the above structure, the belt mechanism of the continuously variable transmission for bicycles is compactly formed even compared with the case of a small motorcycle (LT coefficient is about 4 to 8), and the LT coefficient, which is an index (substitute characteristic) indicating "the ease of belt slippage", is too large, 8 to 12, and under the speed change condition where the pitch circle diameter of the drive pulley is the smallest, even under the severe use conditions (pulley layout, load) such as insufficient friction transmission capacity and extremely easy to induce slippage between the drive pulley and the V-belt, even under the condition indicating the lateral pressure resistance, that is, "relative to the shaft load ( Compared with the case of a small motorcycle (the belt lateral rigidity is about 300 to 1500 N / mm), which is an indicator (substitute characteristic) of the difficulty of buckling deformation due to lateral pressure (the size of the exposed height change), it is possible to ensure a sufficiently high level, thereby suppressing the buckling deformation of the belt (the exposed height change) caused by lateral pressure to a minimum (acceptable level). As a result, slippage can be suppressed and the necessary transmission force can be ensured (for example, a slip ratio of 5% or less).

[0030] Furthermore, the present invention may be characterized in that, in the belt mechanism provided in the above-mentioned bicycle continuously variable transmission, The minimum pitch diameter of the driving pulley is in the range of 40 to 45 mm. The V-belt has a thickness in the range of 7 to 8 mm.

[0031] According to the above configuration, the belt mechanism of the bicycle continuously variable transmission can be formed sufficiently compactly, and the belt lateral rigidity can be kept at a predetermined level (1500-2500 N / mm) even under severe usage conditions (pulley layout, load) with an LT coefficient of 8-12.

[0032] Furthermore, the present invention may be characterized in that the belt mechanism included in the continuously variable transmission for bicycle is mounted on the continuously variable transmission, and the continuously variable transmission is connected to an auxiliary power source of a bicycle equipped with an auxiliary power source.

[0033] According to the above structure, compared with the case where a continuously variable transmission is installed on a bicycle without an auxiliary power source (electric motor, etc.), the space and weight constraints are greater when a continuously variable transmission is installed on a bicycle with an auxiliary power source (electric motor, etc.). Accordingly, the effect of compactly forming the belt mechanism of the continuously variable transmission can be further improved.

[0034] Effects of the Invention

[0035] The present invention can provide a belt mechanism for a bicycle continuously variable transmission which is compact and can suppress slippage and ensure necessary transmission force even under usage conditions where the LT coefficient is too large. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is a schematic diagram showing an example of a belt mechanism included in a general continuously variable transmission. Figure 2 This is a schematic diagram showing an example of a belt mechanism included in the bicycle continuously variable transmission according to the present invention. Figure 3 The diagram is a perspective view showing a cross section in the belt width direction of an example of a V-belt constituting the belt mechanism provided in the bicycle continuously variable transmission according to the present invention. Figure 4 yes Figure 3 A cross-sectional view of the V-belt in the longitudinal direction is shown. Figure 5 This is a schematic diagram for explaining the method (pulley layout) of the exposure height change measurement test. Figure 6 This is a schematic diagram for explaining the method of the exposure height change measurement test (exposure height change amount). Figure 7 This is an explanatory diagram of a biaxial travel tester used for a transmission performance (slip ratio) measurement test. Figure 8 This is an explanatory diagram of a biaxial travel testing machine used for durability performance testing. DETAILED DESCRIPTION

[0037] (Implementation Method)

[0038] Hereinafter, an example of an embodiment of a belt mechanism included in a bicycle continuously variable transmission according to the present invention will be described with reference to the drawings.

[0039] (With mechanism 1)

[0040] like Figure 2 As shown, the belt mechanism 1 of the belt-type continuously variable transmission for a bicycle is the same as that of a small motorcycle, and has a driving pulley 2, a driven pulley 3 and a V-belt 4 (a cut-edge toothed V-belt), and has a structure in which the V-belt 4 is wound around the driving pulley 2 and the driven pulley 3 to change the speed ratio steplessly.

[0041] The driving pulley 2 includes a fixed pulley 21 that cannot move in the direction of the rotation axis and a movable pulley 22 (equivalent to a pair of pulleys) that can move in the direction of the rotation axis (approach and detach freely). The inner peripheral wall of the fixed pulley 21 and the inner peripheral wall of the movable pulley 22 form a V-groove-shaped inclined opposing surface (V-groove 23).

[0042] The driving pulley 2 has a structure that allows the width of a V-groove 23 of the driving pulley 2 formed by the fixed sheave 21 and the movable sheave 22 to be continuously changed.

[0043] The driven pulley 3 also includes a fixed pulley 31 that cannot move in the direction of the rotation axis and a movable pulley 32 (equivalent to a pair of pulleys) that can move in the direction of the rotation axis (can approach and separate freely). The inner peripheral wall of the fixed pulley 31 and the inner peripheral wall of the movable pulley 32 form a V-groove-shaped inclined opposing surface (V-groove 33).

[0044] The driven pulley 3 has a structure that allows the width of a V-groove 33 of the driven pulley 3 formed by the fixed pulley 31 and the movable pulley 32 to be continuously changed.

[0045] The two end faces of the V-belt 4 in the width direction are formed by conical surfaces 4A with consistent inclinations corresponding to the V-groove 23 of the driving pulley 2 and the V-groove 33 of the driven pulley 3, and are embedded in any up-and-down position of the relative surfaces of the V-groove 23 / V-groove 33 according to the changed width of the V-groove 23 / the width of the V-groove 33.

[0046] For example, by widening the width of the V-groove 23 of the driving pulley 2 and narrowing the width of the V-groove 33 of the driven pulley 3, Figure 2 The state indicated by the double-dashed line changes to Figure 2 In the state shown by the solid line (the movable pulley 22 / movable pulley 32 of each pulley is moved to Figure 2 When the V-belt 4 moves in the direction of the arrow in FIG. 1 ), the V-belt 4 moves radially inward (downward) of the V-groove 23 on the driving pulley 2 side, and moves radially outward (upward) of the V-groove 33 on the driven pulley 3 side, and the winding diameter (pitch circle diameter) around the driving pulley 2 and the driven pulley 3 continuously changes, thereby being able to steplessly change the speed ratio.

[0047] The variable speed belt used in such applications is used in a harsh layout where the V-belt 4 is greatly bent and under high load. That is, it is specially designed not only to rotate around the driving pulley 2 and the driven pulley 3, but also to withstand harsh actions under high load environments such as movement in the pulley radius direction and repeated bending caused by continuous changes in the winding radius.

[0048] Although details are omitted, the driving pulley 2 and the driven pulley 3 are constructed so as to convert the belt thrust (pressing force in the direction away from the fixed pulley 21 / 31) acting on the movable pulleys 22, 32 into a pressing force in the direction approaching the fixed pulleys 21 / 31, respectively, by a known cam mechanism or the like (not shown) located on the back side of the movable pulleys 22, 32.

[0049] In addition, if Figure 2As shown in FIG. 1 , the drive shaft 25 (input shaft) and the driven shaft 35 (output shaft) arranged in parallel are connected to the drive side and the driven side at the shaft ends on the opposite sides. That is, the drive pulley 2 and the driven pulley 3 are arranged so that the axial positions of the fixed pulley 21 and the fixed pulley 31 and the axial positions of the movable pulley 22 and the movable pulley 32 are opposite to each other. As a result, when changing speed, the movable pulley 22 and the movable pulley 32 of the drive pulley 2 and the driven pulley 3 move in the same direction ( Figure 2 The V-belt 4 moves in the direction of the arrow, so that no misalignment occurs on the V-belt 4.

[0050] For example, Figure 2 The state shown by the solid line is the state of shifting to the lowest speed side (under the speed change condition where the pitch diameter of the drive pulley 2 is the smallest), where the friction transmission capacity is insufficient, and is equivalent to the state where slippage between the drive pulley 2 and the V-belt 4 is most easily induced.

[0051] Figure 2 The belt mechanism 1 of the bicycle continuously variable transmission shown is an example of the present embodiment. Specifically for bicycle use, in order to make the belt mechanism 1 sufficiently compact, each part is formed with appropriate dimensions [pulley pitch diameter (defined to be described later), distance between axes, V-belt 4 (thickness, belt pitch width, outer circumference), etc.].

[0052] Due to spatial constraints, the minimum pitch circle diameter (d1) of the drive pulley 2 and the driven pulley 3 of the belt mechanism 1 constituting the continuously variable transmission for a bicycle of the present embodiment is limited (suppressed) to, for example, about 45 mm (for example, about 40 to 45 mm), the maximum pitch circle diameter (d2) is limited (suppressed) to, for example, about 80 mm (for example, about 70 to 80 mm), and the inter-axial distance between the drive pulley 2 and the driven pulley 3 is limited (suppressed) to, for example, about 95 mm (for example, about 90 to 200 mm).

[0053] The belt mechanism 1 of the bicycle continuously variable transmission is usually arranged in an internal space covered by a case or the like together with other accompanying mechanisms (such as a speed increasing gear mechanism) and is substantially cut off from the outside in order to suppress the intrusion of foreign matter (such as sand, mud, water, and oil) from the outside.

[0054] As described above, when the belt mechanism 1 of the present embodiment is mounted on a bicycle continuously variable transmission, the belt mechanism 1 is required to be compact, the drive pulley 2 and the driven pulley 3 are required to be small in diameter, and the belt thickness of the V-belt 4 is also limited, compared with the case of a belt type continuously variable transmission mounted on a scooter (displacement 50 to 125cc). In addition, there is a difference that the maximum torque (the maximum value of the torque input to the drive shaft 25 of the belt mechanism 1) is larger than that of a scooter (displacement 50 to 125cc).

[0055] (V-belt 4 (speed belt))

[0056] The V-belt 4 of this embodiment is a speed change belt (cut-edge toothed V-belt 4) used in the belt mechanism 1 of the belt-type continuously variable transmission for bicycles (see Figure 3 , Figure 4 ).

[0057] Hereinafter, the trimmed toothed V-belt 4 of the present embodiment will be described in detail based on the accompanying drawings. Figure 3 As shown, the length direction of the cut-edge toothed V-belt 4 is referred to as the belt length direction, the direction perpendicular to the belt length direction and in which a plurality of core wires are arranged is referred to as the belt width direction, and the direction perpendicular to the belt length direction and the belt width direction is referred to as the belt thickness direction.

[0058] The trimmed toothed V-belt 4 of this embodiment (see Figure 3 , Figure 4 ) The inner circumferential surface of the belt body has a cog portion 41, and the cog portion 41 is alternately arranged along the length direction of the belt to form cog peaks 411 and cog valleys 412. Figure 4 As shown, the cut-edge toothed V-belt 4 has a laminated structure, and has a structure in which a tensile rubber layer 42, a core layer 43, and a compression rubber layer 44 are laminated in sequence from the outer peripheral side of the belt toward the inner peripheral side of the belt (the side where the cog portion 41 is formed). That is, the cut-edge toothed V-belt 4 has a tensile rubber layer 42 laminated on the outer peripheral side of the core layer 43, and a compression rubber layer 44 laminated on the inner peripheral side of the core layer 43.

[0059] The cross-sectional shape in the belt width direction is a trapezoidal shape in which the upper width W, which is the part with the largest belt width, decreases from the outer circumference of the belt toward the inner circumference of the belt. Furthermore, in the core layer 43, the core wires 432 that become the core are buried in a state of being arranged at intervals in the belt width direction, and the cog portion 41 is formed on the compression rubber layer 44 by a cog forming die (not shown).

[0060] Due to the constraints of the spatial surface, the trimmed toothed V-belt 4 of the present embodiment has a belt thickness (H) limited (restricted) to, for example, about 8 mm (for example, about 7 to 9 mm, more preferably 7 to 8 mm), a belt section width (Wp) limited (restricted) to, for example, about 9 mm (for example, about 9 to 14 mm), and further a belt width (W) limited (restricted) to, for example, about 10 mm (for example, about 10 to 15 mm), and a belt outer circumference (BOC) limited (restricted) to, for example, about 400 mm (for example, about 400 to 610 mm).

[0061] In addition, when the compression rubber layer 44 has the cog portion 41 as in the present embodiment, the belt thickness refers to the thickness of the top of the cog portion 41 (the maximum thickness of the belt).

[0062] (Compressed rubber layer 44)

[0063] The compression rubber layer 44 is formed of a rubber composition (crosslinked rubber composition) including a first rubber component.

[0064] (First rubber component)

[0065] As the first rubber component, a rubber that can be vulcanized or cross-linked is preferably used, for example, diene rubber [natural rubber, isoprene rubber, butadiene rubber, chloroprene rubber, styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber (nitrile rubber), hydrogenated nitrile rubber, etc.], ethylene-α-olefin elastomer, chlorosulfonated polyethylene rubber, alkylated chlorosulfonated polyethylene rubber, epichlorohydrin rubber, acrylic rubber, silicone rubber, polyurethane rubber, fluororubber, etc. These rubber components can be used alone or in combination of two or more.

[0066] Among these rubber components, general-purpose ethylene-α-olefin elastomers (ethylene-propylene copolymers (EPM), ethylene-propylene-diene terpolymers (EPDM) and other ethylene-α-olefin rubbers) and chloroprene rubber are preferred from the perspective of easy diffusion of crosslinking agents and crosslinking accelerators. In particular, in the case of speed change belts used in high-load environments, chloroprene rubber and EPDM are preferred from the perspective of excellent balance among mechanical strength, weather resistance, heat resistance, cold resistance, oil resistance, adhesion, etc. Furthermore, chloroprene rubber is particularly preferred from the perspective of excellent wear resistance in addition to the above characteristics. Chloroprene rubber may be a sulfur-modified type or a non-sulfur-modified type.

[0067] When the first rubber component includes chloroprene rubber, the proportion of the chloroprene rubber in the first rubber component may be 50% by mass or more, preferably 80% by mass or more, more preferably 90% by mass or more (particularly 90 to 100% by mass), and most preferably 100% by mass (chloroprene rubber only). When the first rubber component includes an ethylene-α-olefin elastomer, the proportion of the ethylene-α-olefin elastomer is also the same as the proportion of the chloroprene rubber described above.

[0068] (First short fiber)

[0069] The rubber composition forming the compression rubber layer 44 may further include first short fibers. Examples of the first short fibers include polyamide short fibers (polyamide 6 short fibers, polyamide 66 short fibers, polyamide 46 short fibers, aramid short fibers, etc.), polyalkylene arylate short fibers (e.g., polyethylene terephthalate (PET) short fibers, polyethylene naphthalate short fibers, etc.), liquid crystal polyester short fibers, polyarylate short fibers (amorphous wholly aromatic polyester short fibers, etc.), vinylon short fibers, polyvinyl alcohol-based short fibers, poly(p-phenylene benzobisoxazole) (PBO) short fibers and other synthetic short fibers, natural short fibers such as cotton, linen, and wool, and inorganic short fibers such as carbon short fibers. These first short fibers may be used alone or in combination of two or more. Among them, aramid short fibers and PBO short fibers are preferred, and aramid short fibers are particularly preferred.

[0070] The first short fibers may be short fibers obtained by cutting fibers stretched in a fibrous form into a predetermined length. In order to suppress the compression deformation of the V-belt 4 against the lateral pressure from the driving pulley 2 and the driven pulley 3 (i.e., to improve the lateral pressure resistance), the first short fibers are preferably oriented in the belt width direction and buried in the compression rubber layer 44. In addition, the friction coefficient of the surface can be reduced to suppress noise (pronunciation), or the wear caused by friction with the driving pulley 2 and the driven pulley 3 can be reduced, so it is preferred that the short fibers protrude from the surface of the compression rubber layer 44.

[0071] From the perspective of being able to improve lateral pressure resistance and wear resistance without reducing bendability, the average fiber length of the first short fibers may be, for example, about 0.1 to 20 mm, preferably about 0.5 to 15 mm (for example, 0.5 to 10 mm), and more preferably about 1 to 6 mm (particularly about 2 to 4 mm). If the fiber length of the first short fibers is too short, the mechanical properties in the grain direction cannot be sufficiently improved, and the lateral pressure resistance and wear resistance may be reduced. On the contrary, if it is too long, the orientation of the short fibers in the rubber composition is reduced, and the bendability may be reduced.

[0072] From the perspective of being able to impart a high reinforcing effect without reducing the bendability, the single yarn fineness of the first short fiber can be set to, for example, about 1 to 12 dtex, preferably 1.2 to 10 dtex (for example, 1.5 to 8 dtex), and more preferably about 2 to 5 dtex (particularly 2 to 3 dtex). If the single yarn fineness is too large, the lateral pressure resistance and abrasion resistance per unit amount may be reduced, and if the single yarn fineness is too small, the dispersibility into the rubber may be reduced, thereby reducing the bendability.

[0073] In order to improve the adhesion with the first rubber component, the first short fiber can also be subjected to bonding treatment (or surface treatment) by conventional methods. As a surface treatment method, a method of treating with a treatment liquid containing a conventional surface treatment agent can be cited. As a surface treatment agent, for example, there can be cited: an RFL liquid containing resorcinol (R), formaldehyde (F) and rubber or latex (L) [for example, a condensate (RF condensate) formed by resorcinol (R) and formaldehyde (F), an RFL liquid containing the above-mentioned rubber component, such as vinylpyridine-styrene-butadiene copolymer rubber], an epoxy compound, a polyisocyanate compound, a silane coupling agent, a vulcanized rubber composition (for example, a vulcanized rubber composition containing surface silanol groups, containing wet-process white carbon black with hydrous silica as the main component that is beneficial to improving the chemical bonding with rubber, etc.). These surface treatment agents can be used alone or in combination of two or more, and the short fibers can also be treated with the same or different surface treatment agents multiple times in sequence.

[0074] The ratio of the first short fibers is, for example, 5 to 50 parts by mass, preferably 5 to 40 parts by mass (e.g., 8 to 35 parts by mass), and more preferably about 10 to 30 parts by mass (particularly 20 to 30 parts by mass) relative to 100 parts by mass of the first rubber component. If the first short fibers are too little, the lateral pressure resistance and abrasion resistance are reduced, and if they are too much, the processability is reduced, or the bendability of the V-belt 4 is reduced, which may reduce the durability.

[0075] (Other ingredients)

[0076] The rubber composition forming the compression rubber layer 44 may further contain additives. Examples of the additives include vulcanizing agents or crosslinking agents (sulfur-based crosslinking agents, organic peroxides, etc.), co-crosslinking agents (bismaleimides, etc.), crosslinking aids or crosslinking accelerators (thiuram-based accelerators, etc.), vulcanization retarders, metal oxides (zinc oxide, magnesium oxide, calcium oxide, barium oxide, iron oxide, copper oxide, titanium oxide, aluminum oxide, etc.), reinforcing agents (silicon oxides such as carbon black and hydrous silica), fillers (clay, calcium carbonate, talc, mica, etc.), softeners (oils such as paraffin oil and cycloparaffin oil), processing agents or processing aids (stearic acid, stearic acid metal salts, wax, paraffin, fatty acid amide, etc.), antioxidants (antioxidants, heat aging inhibitors, flex crack inhibitors, ozone degradation inhibitors, etc.), colorants, tackifiers, plasticizers, coupling agents (silane coupling agents, etc.), stabilizers (ultraviolet absorbers, heat stabilizers, etc.), flame retardants, antistatic agents, etc. These additives may be used alone or in combination of two or more. In addition, metal oxides may also function as crosslinking agents.

[0077] (Rubber hardness)

[0078] The compression rubber layer 44 has a relatively high rubber hardness for ensuring the belt lateral rigidity (lateral pressure resistance), and the rubber hardness may be, for example, about 93 to 97 degrees, preferably about 95 to 97 degrees.

[0079] In the present application, the rubber hardness of each rubber layer refers to a value Hs (Type A hardness) measured using a Type A durometer in a spring durometer hardness test in accordance with JIS K6253 (2012) (Vulcanized rubber and thermoplastic rubber - Method for determining hardness), and may be simply described as rubber hardness.

[0080] (Stretched rubber layer 42)

[0081] The cut-edge toothed V-belt 4 may further include a tension rubber layer 42 formed of a rubber composition (vulcanized rubber composition) including a second rubber component.

[0082] As the second rubber component, the rubber components exemplified in the first rubber component can be used, and preferred aspects are the same as those of the first rubber component. The second rubber component may be a rubber component different from the first rubber component, but is usually the same as the first rubber component.

[0083] From the viewpoint of being able to further improve the lateral pressure resistance and wear resistance, the rubber composition forming the stretch rubber layer 42 also preferably contains a second short fiber. When not only the compression rubber layer 44 but also the stretch rubber layer 42 contains the second short fiber as the short fiber, the lateral pressure resistance and wear resistance are further improved. As the second short fiber, the short fiber exemplified by the first short fiber can be used, and the preferred method and proportion are also the same as the first short fiber. The second short fiber may also be a short fiber different from the first short fiber, but is usually the same as the first short fiber. The rubber composition forming the stretch rubber layer 42 may further contain other components exemplified by the rubber composition forming the compression rubber layer 44.

[0084] (Rubber hardness)

[0085] From the viewpoint of ensuring the belt lateral rigidity (lateral pressure resistance) and ensuring durability (for example, suppressing cracks in the tensile rubber layer 42), the rubber hardness of the tensile rubber layer 42 may be smaller than the rubber hardness of the compression rubber layer 44. The rubber hardness (A-type hardness) of the tensile rubber layer 42 may be, for example, 89 to 95 degrees, preferably about 89 to 93 degrees (particularly 93 degrees).

[0086] (Core layer 43)

[0087] The core wire 432 used as the core is usually a twisted soft wire arranged at a predetermined interval in the belt width direction. The core wire 432 is arranged to extend along the belt length direction. A plurality of core wires 432 parallel to the belt length direction may be arranged. However, from the viewpoint of productivity, the core wire 432 is usually arranged in a spiral shape extending in parallel at a predetermined interval parallel to the approximate belt length direction of the cut-edge toothed V-belt. When the core wire 432 is arranged in a spiral shape, the angle of the core wire 432 relative to the belt length direction may be, for example, 5° or less. From the viewpoint of the running performance of the belt, the closer to 0°, the more preferable.

[0088] The core layer 43 only needs to include the core wire 432 with adjusted arrangement density and can be formed only by the core wire 432. However, from the viewpoint of suppressing interlayer peeling and improving belt durability, the core layer 43 (adhesive rubber layer 431) is preferably formed by a cross-linked rubber composition in which the core wire 432 is embedded.

[0089] The core layer 43 formed of the cross-linked rubber composition in which the core wire 432 is embedded is generally referred to as an adhesive rubber layer 431. The core wire 432 is embedded in the layer formed of the cross-linked rubber composition containing a rubber component (see Figure 3 , Figure 4 ). The bonding rubber layer 431 is interposed between the tensile rubber layer 42 and the compression rubber layer 44 to bond the tensile rubber layer 42 to the compression rubber layer 44, and the core wire 432 is buried in the bonding rubber layer 431. The buried form of the core wire 432 is not particularly limited, and a part of the core wire 432 may be buried in the bonding rubber layer 431. From the viewpoint of improving durability, it is preferred that the core wire 432 is buried in the bonding rubber layer 431 (that is, the core wire 432 is completely buried in the bonding rubber layer 431).

[0090] (Core 432)

[0091] As the core wire 432 , a twisted cord (for example, ply-twisted, single-twisted, straight-twisted, etc.) using multifilaments can be generally used.

[0092] Examples of the fibers constituting the core wire 432 include general-purpose polyolefin fibers (polyethylene fibers, polypropylene fibers, etc.), polyamide fibers (polyamide 6 fibers, polyamide 66 fibers, polyamide 46 fibers, aramid fibers, etc.), polyester fibers (polyalkylene arylate fibers) [polyethylene terephthalate (PET) fibers, polyethylene naphthalate (PEN) fibers, etc.] 2-4 Alkylene-C 6-14 Synthetic fibers such as aramid fiber, aramid fiber, etc., vinyl fiber, polyvinyl alcohol fiber, poly(p-phenylene benzobisoxazole) fiber, etc., natural fibers such as cotton, linen, wool, etc., and inorganic fibers such as carbon fiber, etc. These fibers can be used alone or in combination of two or more.

[0093] Among these fibers, ethylene terephthalate, ethylene-2,6-naphthalate, and the like are commonly used from the viewpoint of high modulus. 2-4 Alkylene-C 6-12 Synthetic fibers such as polyester fibers (polyalkylene arylate fibers) and polyamide fibers (aramid fibers, etc.), and inorganic fibers such as carbon fibers, etc., wherein aromatic esters are the main constituent units, preferably polyester fibers (especially polyethylene terephthalate fibers and polyethylene naphthalate fibers), polyamide fibers (especially aramid fibers), and most preferably polyamide fibers (especially aramid fibers).

[0094] The total fineness of the core wire 432 may be, for example, 2000 to 17000 dtex, preferably 4000 to 15000 dtex, and more preferably about 6000 to 13000 dtex. The multifilament may include, for example, about 100 to 5000 single filaments, preferably 500 to 4000, and more preferably 1000 to 3000 single filaments.

[0095] The average wire diameter of the core wire 432 (diameter of the stranded cord) may be, for example, 0.5 to 3.0 mm, preferably 0.6 to 2.0 mm, and more preferably about 0.7 to 1.5 mm. If the core wire 432 is too thin, the bending property is improved, but the tension of the V-belt 4 is reduced, and in the worst case, the V-belt 4 is cut. On the other hand, if the core wire 432 is too thick, the bending resistance of the V-belt 4 is reduced, and as a result, the V-belt 4 may be overheated.

[0096] When the core wire 432 is embedded in the adhesive rubber layer 431, it may be subjected to surface treatment in order to improve the adhesion to the cross-linked rubber composition forming the adhesive rubber layer 431. As the surface treatment agent, the surface treatment agent exemplified as the surface treatment agent of the short fiber of the compression rubber layer 44 mentioned above may be cited. The surface treatment agent may be used alone or in combination of two or more, or the treatment may be performed multiple times in sequence using the same or different surface treatment agents. The core wire 432 is preferably subjected to bonding treatment using at least a resorcinol-formalin-latex treatment liquid (RFL liquid).

[0097] (Adhesive rubber layer 431)

[0098] As the rubber component constituting the cross-linked rubber composition forming the adhesive rubber layer 431, the rubber component exemplified as the rubber component of the compression rubber layer 44 can be used, and the preferred embodiment is also the same as the rubber component of the compression rubber layer 44. The rubber composition forming the adhesive rubber layer 431 may further contain the short fibers exemplified by the rubber composition forming the compression rubber layer 44 and other components.

[0099] (Characteristics of the adhesive rubber layer 431)

[0100] The adhesive rubber layer 431 preferably has a lower hardness than the compression rubber layer 44 (or the tensile rubber layer 42). By adjusting the adhesive rubber layer 431 to such a low hardness, it can be deformed greatly when shear stress acts, and the peeling between the core layer 43 and the compression rubber layer 44 and the tensile rubber layer 42 can be suppressed.

[0101] The rubber hardness (A-type hardness) of the adhesive rubber layer 431 is, for example, 60 to 85 degrees, preferably 65 to 84 degrees, more preferably 70 to 83 degrees, and more preferably 75 to 82 degrees (particularly 82 degrees). If the rubber hardness is too low, the lateral pressure resistance may be reduced, and if it is too high, the adhesiveness may be reduced.

[0102] The difference in rubber hardness between the compression rubber layer 44 and the adhesive rubber layer 431 (rubber hardness of the compression rubber layer 44 - rubber hardness of the adhesive rubber layer 431) may be 8 degrees or more, for example, 8 to 37 degrees, preferably 11 to 32 degrees, more preferably 12 to 27 degrees, more preferably 13 to 22 degrees, and most preferably 13 to 15 degrees. If the difference in rubber hardness between the compression rubber layer 44 and the adhesive rubber layer 431 is too small, the heat resistance, lateral pressure resistance, and bending fatigue resistance may not be improved, and if it is too large, the heat resistance, lateral pressure resistance, and bending fatigue resistance may not be improved.

[0103] The average thickness of the adhesive rubber layer 431 is, for example, 0.8 to 3 mm, preferably 1.2 to 2.8 mm, and more preferably 1.5 to 2.5 mm.

[0104] (Reinforced cloth)

[0105] The V-belt 4 of this embodiment does not include a reinforcing cloth, but when the V-belt 4 includes a reinforcing cloth, the reinforcing cloth may be laminated on both (the upper surface of the tensile rubber layer 42 and the lower surface of the compression rubber layer 44) or on either one of the tensile rubber layer 42 and the compression rubber layer 44 (including the cog portion 41). In addition, the reinforcing cloth may be buried in the compression rubber layer 44 and / or the tensile rubber layer 42.

[0106] The reinforcing cloth may be, for example, woven cloth, wide-angle woven cloth, knitted cloth, nonwoven cloth or other cloth (particularly woven cloth). The cloth may be treated (impregnated, coated, etc.) with a liquid adhesive (RFL liquid, rubber paste, etc.), rubbed by scraping a highly adhesive rubber composition into the mesh of the cloth, or laminated with a highly adhesive rubber composition sheet on the cloth, as required.

[0107] (Explanation of the conditions of use of mechanism 1: Issue)

[0108] In the belt mechanism 1 of the bicycle continuously variable transmission, the LT (Limit Torque) coefficient defined in the formula 1 described later, which is an index (substitute characteristic) indicating the ease of slippage of the V-belt 4, becomes too large, and the friction transmission capacity is insufficient under the speed change condition where the pitch diameter of the drive pulley 2 is the smallest, and the belt mechanism 1 is placed under harsh usage conditions (pulley layout, load) that easily induce slippage between the drive pulley 2 and the V-belt 4. In the case of a small motorcycle, the LT coefficient is about 4 to 8, while under the above usage conditions, the LT coefficient is about 8 to 12, which exceeds the actual range of a small motorcycle.

[0109] That is, in the belt mechanism 1 of the bicycle continuously variable transmission of the present embodiment, it is assumed that the LT coefficient of the V-belt 4 with respect to the drive pulley 2 is in the range of 8 to 12 under the use condition of maximum torque in the state of shifting to the lowest speed side (shifting condition in which the pitch circle diameter of the drive pulley 2 is the smallest). Specifically, Figure 2 The state shown by the solid line is the state of shifting to the lowest speed side (the speed shifting condition where the pitch diameter of the drive pulley 2 is the smallest), which corresponds to the state where the friction transmission capacity is insufficient and the slip between the drive pulley 2 and the V-belt 4 is most likely to be induced.

[0110] (Explanation of the conditions of use of mechanism 1: Definition)

[0111] [definition]

[0112] ・Node line

[0113] The pitch line refers to the center line of the core (core wire 432 ) buried in the V-belt 4 .

[0114] like Figure 3 As shown, sometimes it means the node line extending along the width direction of the belt, such as Figure 4 As shown, sometimes it means the pitch lines extending along the length of the belt.

[0115] ・Pitch width (Wp)

[0116] The belt pitch width refers to the length of the belt width along the pitch line (refer to Figure 3 ).

[0117] ・Pulley pitch diameter (d)

[0118] The pulley pitch circle diameter refers to the diameter of a circle (pitch circle) formed by the pitch line of the portion where the V-belt 4 is wound around the pulley (ie, the winding diameter).

[0119] It is twice the pulley pitch radius (r) mentioned below (d = 2r).

[0120] ・Pulley pitch radius (r)

[0121] It is the radius of a circle (pitch circle) formed by the pitch line of the portion where the V-belt 4 is wound around the pulley.

[0122] ・Minimum pitch diameter (d1)

[0123] It is the minimum value (lower limit value) of the pulley pitch diameter (d) when the V-belt 4 is wound around the pulley.

[0124] It is twice the minimum pitch circle radius (r1) mentioned below (d1 = 2r1).

[0125] ・Minimum pitch circle radius (r1)

[0126] The minimum value (lower limit value) of the pulley pitch radius (r) when the V-belt 4 is wound around the pulley.

[0127] ・LT coefficient

[0128] The LT (Limit Torque) factor is an indicator (a proxy characteristic) that indicates "how easy it is for the belt to slip."

[0129] (Explanation of the use conditions with mechanism 1: LT coefficient)

[0130] When a speed change belt mechanism such as the belt mechanism 1 of the bicycle continuously variable transmission of the present embodiment is taken as an object, the LT coefficient is set as a coefficient expressed by a numerical value obtained by dividing the effective tension borne by the drive pulley 2 by the area of ​​the friction transmission surface (the product of the winding length (L) and the belt thickness (H)), and can be expressed by Formula 1.

[0131] (Equation 1) LT coefficient

[0132] LT coefficient = effective tension (Te) / winding length (L) / tape thickness (H)

[0133] In addition, the unit of the LT coefficient calculated as follows is strictly kgf / cm 2 , but for convenience, it is expressed as dimensionless.

[0134] Here, the effective tension (Te) (unit: kgf) refers to the tension for rotating the pulley (the difference between the tension on the tension side and the tension on the slack side), and can be expressed by Formula (2).

[0135] (Equation 2) Effective tension

[0136] Te = Tmax / (r / 100) / 9.81

[0137] Tmax: Maximum torque (unit: Nm) ... the maximum value of the torque input to the drive shaft

[0138] r: Pulley pitch circle radius (unit: cm) ... can be calculated as the radius of the circle (pitch circle) formed by the pitch line of the portion of the belt wound around the pulley.

[0139] The winding length (L) (unit: cm) refers to the length of the portion of the belt wound around the pulley along the pitch line, and can be expressed by Formula 3.

[0140] (Equation 3) Winding length

[0141] L = r × θ

[0142] θ: winding angle (contact angle) (unit: radian) ... can be calculated as the center angle of the portion of the belt wound around the pulley with respect to the arc formed by the pitch line.

[0143] Belt thickness (H) (unit: cm): Total belt thickness (the thickness of the entire belt including the cogs)

[0144] The LT coefficient for the drive pulley under the use condition of maximum torque when the speed is shifted to the lowest speed side specified in the present application is calculated by replacing the above-mentioned "pulley pitch circle radius" (r) with the "minimum pitch circle radius" (r1) of the drive pulley.

[0145] (Explanation of the use conditions of mechanism 1: Meaning of the numerical range of the LT coefficient)

[0146] If the LT coefficient is too large (e.g., about 8 to 12 as in the present embodiment), it means that the friction transmission capacity is insufficient and slippage between the drive pulley 2 and the V-belt 4 is extremely likely to occur under severe usage conditions (pulley layout, load).

[0147] The smaller the value of the LT coefficient is, the more margin there is in the friction transmission capacity, and stable travel (for example, travel with a slip ratio of 5% or less) can be expected.

[0148] (With lateral rigidity: description)

[0149] The belt lateral rigidity is an index (substitute characteristic) indicating the lateral pressure resistance of the V-belt 4 (per belt), that is, “the difficulty of buckling deformation under axial load (lateral pressure)” (the magnitude of the exposure height variation described later).

[0150] That is, the value (N / mm) of the axial load (N) relative to the exposure height change amount (mm) in the exposure height change measurement test was defined as the belt lateral rigidity (N / mm).

[0151] (Belt lateral rigidity: exposure height change measurement test)

[0152] [Testing machine]

[0153] Exposure height change measuring machine

[0154] [Measurement method] (1) The V-belt 4 is hung on the driving pulley and the driven pulley and an initial load (axial load 200N) is applied. The belt is then run under the specified test conditions (pitch diameter of the driving pulley 45mm, pitch diameter of the driven pulley 45mm, drive shaft speed 50rpm, axial load varying between 200N and 1000N, ambient temperature 23±2°C). (Refer to Figure 5 (2) Change the shaft load (increase in steps from 200N to 1000N) and measure the change in the exposed height of the drive pulley side using a laser displacement meter (refer to Figure 6 ), a line graph (curve graph) showing the relationship between the axial load (N) and the change in exposed height (mm) is obtained. (3) Based on the slope of the straight line approximation for the axial load range of 400N to 1000N on the curve graph (the slope of the approximate straight line connecting the passing point on the curve graph when the axial load is 400N and the passing point on the curve graph when the axial load is 1000N), the belt lateral stiffness [the value (N / mm) of the axial load (N) relative to the change in exposed height (mm)] is calculated.

[0155] Here, the exposure height (RO) refers to the radial separation distance (mm) between the outer peripheral surface of the V-belt 4 (the outer peripheral surface of the belt on the belt width bisecting line: the measurement position of the laser displacement meter) and the outer peripheral surface of the drive pulley (V-belt pulley) (see Figure 6 ).

[0156] The exposure height (RO) change (mm) is the value obtained by subtracting the exposure height (mm) under the initial load (axial load 200N) from the exposure height (mm) under each axial load after the change (refer to Figure 6 ).

[0157] (With transverse rigidity: meaning of numerical range)

[0158] The belt transverse rigidity of the V-belt 4 according to the present embodiment in the exposure height variation measurement test is within a range of 1500 to 2500 N / mm.

[0159] If the belt lateral rigidity is less than 1500 N / mm, the slip of the V-belt 4 with respect to the drive pulley 2 within the LT coefficient range of 8 to 12 cannot be suppressed (for example, the slip ratio exceeds 5%), and the necessary transmission force cannot be ensured (for example, the slip ratio is less than 5%).

[0160] On the other hand, when the lateral belt rigidity exceeds 2500 N / mm, the bending rigidity of the V-belt 4 becomes too large, and the winding property of the V-belt 4 around the drive pulley 2 (the bending property of the V-belt 4) cannot be ensured under the minimum pitch diameter used (the speed change condition where the pitch diameter of the drive pulley 2 is the smallest: for example, 45 mm).

[0161] (Manufacturing method of trimmed toothed V-belt 4)

[0162] The method for manufacturing the trimmed toothed V-belt 4 is not particularly limited, and a conventional method can be used for the lamination step of each layer (the method for manufacturing the belt sleeve). A typical method for manufacturing the trimmed toothed V-belt 4 (in the case of a structure having a reinforcing cloth) will be described.

[0163] First, a laminate of a reinforcing cloth (lower cloth) and a sheet for a compression rubber layer (uncrosslinked rubber sheet) is placed in contact with a flat cog die having teeth and grooves alternately arranged therein, and is pressed at a temperature of about 60 to 100° C. (particularly 70 to 80° C.) to produce a cog pad (a pad that is not completely crosslinked but in a semi-crosslinked state) having the cog portion 41 formed therein. The two ends of the cog pad may be vertically cut from an appropriate position (particularly the top of the cog peak 411).

[0164] Next, the inner mother mold having teeth and grooves corresponding to the cog portion 41 arranged alternately is placed on the cylindrical mold, and the cog pad is wound around the outer periphery of the inner mother mold so that both ends (particularly the top of the cog peak 411) are joined while the cog pad is engaged with the teeth and groove, thereby installing the cog pad. Then, after the second bonding rubber layer sheet (lower bonding rubber: uncrosslinked rubber sheet) is wound around the outer periphery of the installed cog pad, the core wire 432 (twisted cord) forming the core body is spun into a spiral shape, and then the first bonding rubber layer sheet (upper contact rubber: uncrosslinked rubber sheet), the stretching rubber layer sheet (uncrosslinked rubber sheet), and the reinforcing cloth (upper cloth) are wound around the outer periphery in order to produce an uncrosslinked belt precursor.

[0165] Then, the belt is cross-linked and molded using a known cross-linking device (such as a vulcanizer) to produce a belt sleeve. Then, the belt is cut into a V-shape using a cutter or the like to obtain a cut-edge toothed V-belt 4.

[0166] Furthermore, the adhesive rubber layer 431 may be formed of one or more adhesive rubber layer sheets, and the core wire 432 (twisted cord) forming the core body may be spun in association with the number of adhesive rubber layer sheets and the stacking order according to the embedding position in the adhesive rubber layer 431 .

[0167] (Effect)

[0168] According to the above structure, in the belt mechanism 1 provided in the continuously variable transmission for bicycles, compared with the case of a small motorcycle (LT coefficient is about 4 to 8), the LT coefficient, which is an index (substitute characteristic) indicating "the ease of belt slippage", is too large, 8 to 12. Under the speed change condition where the pitch circle diameter of the drive pulley 2 is the smallest, even if the friction transmission capacity is insufficient, it is very easy to induce slippage between the drive pulley 2 and the V-belt 4 under such harsh use conditions (pulley layout, load), even if it is in accordance with the lateral pressure resistance, that is, "relative to the shaft load ( The belt lateral rigidity (rigidity in the belt width direction), which is an indicator (substitute characteristic) of the difficulty of buckling deformation due to lateral pressure) (size of change in exposed height), is 1500~2500N / mm. Compared with the case of a small motorcycle (the belt lateral rigidity is about 300~1500N / mm), it can be ensured to be at a sufficiently high level, so that the buckling deformation (change in exposed height) of the V-belt 4 caused by lateral pressure can be suppressed to a minimum (qualified level). As a result, slippage can be suppressed and the necessary transmission force (for example, slippage rate of 5% or less) can be ensured.

[0169] In the belt mechanism 1, the minimum pitch diameter of the drive pulley 2 may be set to a range of 40 to 45 mm, and the belt thickness of the V-belt 4 may be set to a range of 7 to 8 mm. According to this configuration, the belt mechanism 1 provided in the bicycle continuously variable transmission can be formed sufficiently compactly, and even under severe use conditions (pulley layout, load) where the LT coefficient is 8 to 12, the belt lateral rigidity can be made to a predetermined level (1500 to 2500 N / mm).

[0170] (Other Implementations)

[0171] The belt mechanism 1 included in the bicycle continuously variable transmission may be mounted on a continuously variable transmission (belt-type continuously variable transmission (CVT) for bicycles with electric assist) connected to an auxiliary power source of a bicycle equipped with an auxiliary power source.

[0172] According to this structure, compared with the case where a bicycle without an auxiliary power source (electric motor, etc.) is equipped with a continuously variable transmission, the space and weight constraints are greater when a bicycle with an auxiliary power source (electric motor, etc.) is equipped with a continuously variable transmission. Accordingly, the effect of compactly forming the belt mechanism 1 of the continuously variable transmission can be further improved.

[0173] Example

[0174] In the present invention, even when a V-belt is used as a belt mechanism of a bicycle continuously variable transmission that is compact and used under conditions where the LT coefficient is too large, it is necessary to suppress slippage and ensure necessary transmission force.

[0175] Therefore, in this embodiment, the belt mechanisms involved in Examples 1 to 9, Comparative Examples 1 to 7 and Reference Example 1 (hereinafter referred to as test pieces) were produced, and compactness evaluation and belt running tests [transmission performance (slip ratio) measurement test, durability performance test] were carried out for comparative verification.

[0176] Furthermore, the present invention will be described in more detail below based on examples, but the present invention is not limited to these examples.

[0177] [Material used for V-belts]

[0178] (core wire)

[0179] As core wires of the V-belts of the respective test pieces, twisted cords of the configurations A1 to A2 shown in Table 1 were produced.

[0180] A1 twisted cord is manufactured according to the following steps.

[0181] Two bundles of aramid fiber multifilaments with a fineness of 1,680 dtex were paralleled and pre-twisted, and three of the combined yarns were pre-twisted in the direction opposite to the pre-twisted direction to prepare a twisted cord (average wire diameter 1.19 mm) with a total fineness of 10,080 dtex, and further a treated cord subjected to an adhesive treatment was prepared.

[0182] The A2 twisted cord is prepared by drawing two bundles of polyethylene terephthalate (PET) fiber multifilaments with a fineness of 1,100 dtex together and twisting them initially, and then twisting three of the combined yarns in the opposite direction of the initial twist to make a twisted cord (average wire diameter of 1.00 mm) with a total fineness of 6,600 dtex, and then applying an adhesive treatment to prepare a treated cord.

[0183] [Table 1]

[0184] (Elastic modulus of the core wire)

[0185] Here, a method for measuring the elastic modulus (tensile elastic modulus) of the core wire (in the longitudinal direction) shown in Table 1 will be described.

[0186] A chuck (jig) was attached to the lower fixing portion and the upper load cell connecting portion of Autograph (AGS-J10kN manufactured by Shimadzu Corporation), and both ends of the core wire were grasped by the chuck.

[0187] Next, in the stress-strain curve measured when the core wire was stretched at a speed of 250 mm / min until cut, the slope of the straight line in the region of a relatively straight line relationship (100 to 200 N) was calculated as the tensile elastic modulus of the core wire.

[0188] The measurement results are organized as indices when the elastic modulus (MPa) of the core wire of A1 is set to 100.

[0189] (Rubber composition)

[0190] The rubber compositions C1 to C5 having the compositions shown in Tables 2 to 3 were kneaded in a Banbury mixer to prepare block-shaped uncrosslinked rubber compositions. The obtained uncrosslinked rubber compositions were passed through a calender roll to form a calendered rubber sheet of a predetermined thickness, thereby preparing an uncrosslinked rubber sheet forming each rubber layer. The results of measuring the hardness and tensile strength of the crosslinked product (crosslinked rubber) of each rubber composition are also shown in Tables 2 to 3.

[0191] [Table 2]

[0192] [Table 3]

[0193] (Raw materials for rubber composition) Chloroprene rubber: Denka Corporation "PM-40" Magnesium oxide: Kyowa Chemical Industry Co., Ltd. "KYOWAMAG 30" Stearic acid: NOF Corporation "Stearic acid Tsubaki" Anti-aging agent: Seiko Chemical Co., Ltd. "NONFLEX OD-3" Carbon black: "SEAST 3" manufactured by Tokai Carbon Co., Ltd. Silica: Evonik Japan Co., Ltd., "ULTRASIL (registered trademark) VN3", BET specific surface area 175 m 2 / g Plasticizer: ADEKA CIZER RS-700 manufactured by ADEKA Corporation Cross-linking accelerator: "NOCCELER TT" manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Zinc oxide: "Zinc oxide 3 types" manufactured by Shodo Chemical Industry Co., Ltd. N,N'-m-phenylene dimaleimide: "VULNOC PM" manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Aramid staple fibers: Teijin Limited's "Conex staple fibers" (average fiber length 3 mm, average fiber diameter 14 μm) were bonded with an RFL solution [2.6 parts by mass of resorcinol, 1.4 parts by mass of 37% formalin, 17.2 parts by mass of vinylpyridine-styrene-butadiene copolymer latex (ZEON Corporation, Japan) and 78.8 parts by mass of water] to obtain staple fibers with a solid content adhesion rate of 6%

[0194] (Rubber hardness Hs of cross-linked rubber)

[0195] Each rubber layer was pressed and heated with an uncrosslinked rubber sheet at a temperature of 160°C for 30 minutes to produce a crosslinked rubber sheet (100 mm × 100 mm × 2 mm thickness). A laminate of three crosslinked rubber sheets was used as a sample, and the hardness of the crosslinked rubber sheet was measured using a type A durometer according to the spring durometer hardness test specified in JIS K 6253 (2012).

[0196] (Tensile strength of cross-linked rubber)

[0197] A cross-linked rubber sheet prepared for measuring the rubber hardness Hs of the cross-linked rubber was used as a sample, and a test piece punched into a dumbbell shape (No. 5 shape) was prepared in accordance with JIS K6251 (2017). In a sample containing short fibers, a dumbbell-shaped test piece was collected in such a way that the arrangement direction of the short fibers (grain parallel direction) became the tensile direction. Then, the two ends of the test piece were grasped with a chuck (clamp), and the maximum tensile force recorded when the test piece was pulled at a speed of 500 mm / min until it was cut was divided by the initial cross-sectional area of ​​the test piece (tensile strength T) as the tensile strength.

[0198] [V-belt production]

[0199] Using the A1 to A2 cords (adhesive treated products) and C1 to C5 rubber compositions (uncrosslinked rubber sheets) described in the above materials, V-belts (cut-edge toothed V-belts) of each test piece were produced by the method described in the above embodiment (but without using reinforcing cloth).

[0200] Crosslinking was performed at 180°C for 30 minutes to produce a belt sleeve (crosslinked sleeve) having a predetermined cogging portion formed on the outer circumference. The obtained crosslinked sleeve was cut into a predetermined width (upper width W) with a cutter, and the side surface was further cut into a V shape at a V angle of 20°. Then, the inner and outer circumferences were reversed, a cogging portion was formed on the inner circumference, and a V-belt (cut-edge toothed V-belt) having predetermined dimensions (described in Tables 5 to 11) [belt thickness (H), belt section width (Wp), belt outer circumference length (BOC)] was obtained for each test piece.

[0201] [Drive pulley and driven pulley]

[0202] The driving pulley and the driven pulley were configured to have predetermined dimensions (described in Tables 5 to 11) [minimum pitch circle diameter (d1), maximum pitch circle diameter (d2), and distance between axes] for each test piece.

[0203] [LT coefficient]

[0204] The LT coefficient of the V-belt with respect to the driving pulley was calculated for each test piece according to the method (Formulas 1 to 3) described in the above-mentioned embodiment (Description of the use conditions of the belt mechanism 1: LT coefficient), using the dimensions of each part of the "V-belt" and "driving pulley and driven pulley" set for each test piece and the value of the maximum torque (the maximum value of the torque input to the drive shaft) (Tmax).

[0205] In addition, the maximum torque (Tmax) was uniformly set to 10 Nm among the test pieces.

[0206] [With lateral rigidity]

[0207] The belt lateral rigidity (P) [value (N / mm) of the axial load (N) relative to the exposure height change (mm) in the exposure height change measurement test] was measured for each test piece (V-belt) according to the exposure height change measurement test method described in the above embodiment (Belt lateral rigidity: description).

[0208] [Overview of each specimen]

[0209] The outline of each test piece (production of the V-belt, configuration of the drive pulley and the driven pulley, actual values ​​of the LT coefficient and the belt lateral rigidity) is shown below in the order of the test pieces recorded in Tables 5 to 11 of the verification results described later based on Example 1.

[0210] [Example 1]

[0211] (V-belt)

[0212] A V-belt (cut-edge toothed V-belt) was obtained by making a belt sleeve (cross-linked sleeve) with a thickness of 8 mm using an aromatic polyamide core wire of A1, an adhesive rubber sheet (uncross-linked rubber sheet) of a rubber composition C1 (rubber hardness 82° after cross-linking), a stretched rubber sheet (uncross-linked rubber sheet) of a rubber composition C3 (rubber hardness 93° after cross-linking), and a compressed rubber sheet (uncross-linked rubber sheet) of a rubber composition C4 (rubber hardness 95° after cross-linking).

[0213] The dimensions of the obtained V-belt were as follows: belt thickness (H) was 8 mm (wherein the height of the cog peak was 4 mm), belt pitch width (Wp) was 9.3 mm, and belt outer circumference (BOC) was 400 mm.

[0214] (Drive pulley and driven pulley)

[0215] When the minimum pitch circle diameter (d1) was set to 45 mm and the maximum pitch circle diameter (d2) was set to 80 mm and the above-mentioned V-belt was used, the distance between the axes became 94 mm.

[0216] (LT coefficient, with lateral rigidity)

[0217] As a result, the LT coefficient of the V-belt with respect to the drive pulley is 9.1, and the belt lateral rigidity (P) is 2000N / mm. The details of the calculation process of the LT coefficient (Formulas 1 to 3) are as follows.

[0218] (Equation 1) LT coefficient LT coefficient = effective tension (Te) / winding length (L) / belt thickness (H) = 45.3 / 6.23 / 0.8 = 9.1 (Equation 2) Effective tension (Te) Te=Tmax / (r / 100) / 9.81=10 / (4.5 / 2 / 100) / 9.81=45.3(kgf) (Formula 3) Winding length (L) L=r×θ=(4.5 / 2)×2.77=6.23(cm) In addition, θ [the winding angle (contact angle) of the belt relative to the drive pulley (minimum pitch diameter)] in the formula is 2.77 radians (159 degrees).

[0219] [Example 2]

[0220] (V-belt)

[0221] A belt sleeve (cross-linked sleeve) with a thickness of 8 mm was produced using the same materials as in Example 1 to obtain a V-belt (cut-edge toothed V-belt). The dimensions (thickness, section width, and outer circumference) of the obtained V-belt were also the same as in Example 1.

[0222] (Drive pulley and driven pulley)

[0223] Compared with Example 1, the maximum pitch circle diameter (d2) was not changed to 80 mm, the minimum pitch circle diameter (d1) was changed to 40 mm, and the above-mentioned V-belt was used. As a result, the distance between the axes became 97 mm.

[0224] In addition, in this variable speed belt mechanism (belt thickness of about 8mm, belt pitch width of about 9mm), when the V-belt is hung between the pulleys, if the pulley pitch diameter is less than 40mm, the V-belt (inner circumference) may contact the rotating shaft (outer circumference) of the pulley. Therefore, it can be said that the pulley pitch diameter of 40mm corresponds to the lower limit of the allowable range that can function normally as a variable speed belt mechanism.

[0225] (LT coefficient, with lateral rigidity)

[0226] As a result, the LT coefficient of the V-belt with respect to the drive pulley was 12, and the belt lateral rigidity (P) was 2000 N / mm.

[0227] [Example 3]

[0228] (V-belt)

[0229] A V-belt (trimmed-edge toothed V-belt) was obtained by making a belt sleeve (cross-linked sleeve) with a thickness of 8 mm using the same materials as in Example 1 except that the core wire was changed to A2 (PET core wire). The dimensions (thickness, section width, and outer circumference) of the obtained V-belt were also the same as in Example 1.

[0230] (Drive pulley and driven pulley)

[0231] The dimensions are the same as those of Example 1 (minimum pitch circle diameter, maximum pitch circle diameter, and axis distance).

[0232] (LT coefficient, with lateral rigidity)

[0233] As a result, the LT coefficient of the V-belt with respect to the drive pulley was 9.1, and the belt lateral rigidity (P) was 1500 N / mm.

[0234] [Comparative Example 1]

[0235] (V-belt)

[0236] A V-belt (cut-edge toothed V-belt) was obtained by using the same materials as in Example 1 except that the rubber composition of the compressed rubber sheet (uncrosslinked rubber sheet) was changed to C3 (rubber hardness after crosslinking: 93°). The dimensions (thickness, section width, outer circumference) of the obtained V-belt were also the same as in Example 1.

[0237] (Drive pulley and driven pulley)

[0238] The dimensions are the same as those of Example 1 (minimum pitch circle diameter, maximum pitch circle diameter, and axis distance).

[0239] (LT coefficient, with lateral rigidity)

[0240] As a result, the LT coefficient of the V-belt with respect to the drive pulley was 9.1, and the belt lateral rigidity (P) was 1000 N / mm.

[0241] [Comparative Example 2]

[0242] (V-belt)

[0243] A V-belt (cut-edge toothed V-belt) was obtained by using the same materials as in Example 1 except that the rubber composition of the compressed rubber sheet (uncrosslinked rubber sheet) was changed to C5 (rubber hardness after crosslinking: 97°). The dimensions (thickness, section width, outer circumference) of the obtained V-belt were also the same as in Example 1.

[0244] (Drive pulley and driven pulley)

[0245] The dimensions are the same as those of Example 1 (minimum pitch circle diameter, maximum pitch circle diameter, and axis distance).

[0246] (LT coefficient, with lateral rigidity)

[0247] As a result, the LT coefficient of the V-belt with respect to the drive pulley was 9.1, and the belt lateral rigidity (P) was 2700 N / mm.

[0248] [Example 4]

[0249] (V-belt)

[0250] A V-belt (cut-edge toothed V-belt) was obtained by using the same materials as in Comparative Example 2 except that the thickness of the compressed rubber sheet (uncrosslinked rubber sheet) and the thickness of the stretched rubber sheet (uncrosslinked rubber sheet) were changed (reduced by 0.5 mm each). The belt sleeve (crosslinked sleeve) having a thickness of 7 mm was produced. The dimensions of the obtained V-belt were as follows: the belt thickness (H) was 7 mm (wherein the height of the cog peak was 4 mm), the belt section width (Wp) was 9.3 mm, and the belt outer circumference (BOC) was 397 mm.

[0251] (Drive pulley and driven pulley)

[0252] The dimensions are the same as those of Example 1 (minimum pitch circle diameter, maximum pitch circle diameter, and axis distance).

[0253] (LT coefficient, with lateral rigidity)

[0254] As a result, the LT coefficient of the V-belt with respect to the drive pulley was 10, and the belt lateral rigidity (P) was 2200 N / mm.

[0255] [Comparative Example 3]

[0256] (V-belt)

[0257] A V-belt (cut-edge toothed V-belt) was obtained by using the same materials as in Example 1 except that the thickness of the compressed rubber sheet (uncrosslinked rubber sheet) was changed (thinned by 0.5 mm) and the thickness of the stretched rubber sheet (uncrosslinked rubber sheet) was changed (thinned by 1.0 mm). The belt sleeve (crosslinked sleeve) having a thickness of 6 mm was produced. The dimensions of the obtained V-belt were as follows: the belt thickness (H) was 6 mm (wherein the height of the cog peak was 3 mm), the belt section width (Wp) was 9.3 mm, and the belt outer circumference (BOC) was 397 mm.

[0258] (Drive pulley and driven pulley)

[0259] The dimensions are the same as those of Example 1 (minimum pitch circle diameter, maximum pitch circle diameter, and axis distance).

[0260] (LT coefficient, with lateral rigidity)

[0261] As a result, the LT coefficient of the V-belt with respect to the drive pulley was 12, and the belt lateral rigidity (P) was 800 N / mm.

[0262] [Example 5]

[0263] (V-belt)

[0264] A V-belt (cut-edge toothed V-belt) was obtained by using the same materials as in Example 1 except that the thickness of the compressed rubber sheet (uncrosslinked rubber sheet) and the thickness of the stretched rubber sheet (uncrosslinked rubber sheet) were changed (reduced by 0.5 mm each). The belt sleeve (crosslinked sleeve) having a thickness of 7 mm was produced. The dimensions of the obtained V-belt were as follows: the belt thickness (H) was 7 mm (wherein the height of the cog peak was 4 mm), the belt section width (Wp) was 9.3 mm, and the belt outer circumference (BOC) was 397 mm.

[0265] (Drive pulley and driven pulley)

[0266] The dimensions are the same as those of Example 1 (minimum pitch circle diameter, maximum pitch circle diameter, and axis distance).

[0267] (LT coefficient, with lateral rigidity)

[0268] As a result, the LT coefficient of the V-belt with respect to the drive pulley was 10, and the belt lateral rigidity (P) was 1500 N / mm.

[0269] [Example 6]

[0270] (V-belt)

[0271] A V-belt (cut-edge toothed V-belt) was obtained by using the same materials as in Example 1, except that the thickness of the compressed rubber sheet (uncrosslinked rubber sheet) was changed (thickened by 1 mm), and a belt sleeve (crosslinked sleeve) with a thickness of 9 mm was produced. The dimensions of the obtained V-belt were the same as in Example 1 (section width, outer circumference length), except that the belt thickness (H) was changed to 9 mm (wherein the height of the cog peak was 4 mm).

[0272] (Drive pulley and driven pulley)

[0273] The dimensions are the same as those of Example 1 (minimum pitch circle diameter, maximum pitch circle diameter, and axis distance).

[0274] (LT coefficient, with lateral rigidity)

[0275] As a result, the LT coefficient of the V-belt with respect to the drive pulley was 8.1, and the belt lateral rigidity (P) was 2500 N / mm.

[0276] [Comparative Example 4]

[0277] (V-belt)

[0278] A V-belt (cut-edge toothed V-belt) was obtained by using the same materials as in Example 6 except that the rubber composition of the compressed rubber sheet (uncrosslinked rubber sheet) was changed to C5 (rubber hardness after crosslinking: 97°). The dimensions (thickness, section width, outer circumference) of the obtained V-belt were also the same as in Example 6.

[0279] (Drive pulley and driven pulley)

[0280] The dimensions are the same as those of Example 1 (minimum pitch circle diameter, maximum pitch circle diameter, and axis distance).

[0281] (LT coefficient, with lateral rigidity)

[0282] As a result, the LT coefficient of the V-belt with respect to the drive pulley was 8.1, and the belt lateral rigidity (P) was 3000 N / mm.

[0283] [Example 7]

[0284] (V-belt)

[0285] A V-belt (cut-edge toothed V-belt) was obtained by using the same materials as in Example 6 except that the rubber composition of the compressed rubber sheet (uncrosslinked rubber sheet) was changed to C3 (rubber hardness after crosslinking: 93°). The dimensions (thickness, section width, outer circumference) of the obtained V-belt were also the same as in Example 6.

[0286] (Drive pulley and driven pulley)

[0287] The dimensions are the same as those of Example 1 (minimum pitch circle diameter, maximum pitch circle diameter, and axis distance).

[0288] (LT coefficient, with lateral rigidity)

[0289] As a result, the LT coefficient of the V-belt with respect to the drive pulley was 8.1, and the belt lateral rigidity (P) was 1500 N / mm.

[0290] [Comparative Example 5]

[0291] (V-belt)

[0292] A V-belt (trimmed-edge toothed V-belt) was obtained by making a belt sleeve (cross-linked sleeve) with a thickness of 9 mm using the same materials as in Example 7 except that the core wire was changed to A2 (PET core wire). The dimensions (thickness, section width, and outer circumference) of the obtained V-belt were also the same as in Example 7.

[0293] (Drive pulley and driven pulley)

[0294] The dimensions are the same as those of Example 1 (minimum pitch circle diameter, maximum pitch circle diameter, and axis distance).

[0295] (LT coefficient, with lateral rigidity)

[0296] As a result, the LT coefficient of the V-belt with respect to the drive pulley was 8.1, and the belt lateral rigidity (P) was 1100 N / mm.

[0297] [Comparative Example 6]

[0298] (V-belt)

[0299] Using the same materials as in Comparative Example 2 (aramid core wire, compression rubber layer hardness 97°), a belt sleeve (cross-linked sleeve) with a thickness of 8 mm was produced to obtain a V-belt (cut-edge toothed V-belt). The dimensions (thickness, section width, outer circumference) of the obtained V-belt were also the same as those in Comparative Example 2.

[0300] (Drive pulley and driven pulley)

[0301] With respect to Comparative Example 2, the maximum pitch circle diameter (d2) was not changed to 80 mm, the minimum pitch circle diameter (d1) was changed to 40 mm, and the above-mentioned V-belt was used. As a result, the distance between the axes was 97 mm.

[0302] (LT coefficient, with lateral rigidity)

[0303] As a result, the LT coefficient of the V-belt with respect to the drive pulley was 12, and the belt lateral rigidity (P) was 2700 N / mm.

[0304] [Example 8]

[0305] (V-belt)

[0306] A V-belt (cut-edge toothed V-belt) was obtained by making a belt sleeve (cross-linked sleeve) with a thickness of 8 mm using the same materials as in Comparative Example 6 except that the core wire was changed to A2 (PET core wire). The dimensions (thickness, section width, outer circumference) of the obtained V-belt were also the same as those in Comparative Example 6.

[0307] (Drive pulley and driven pulley)

[0308] The dimensions are the same as those of Comparative Example 6 (minimum pitch circle diameter, maximum pitch circle diameter, and axis distance).

[0309] (LT coefficient, with lateral rigidity)

[0310] As a result, the LT coefficient of the V-belt with respect to the drive pulley was 12, and the belt lateral rigidity (P) was 2500 N / mm.

[0311] [Example 9]

[0312] (V-belt)

[0313] A V-belt (cut-edge toothed V-belt) was obtained by using the same materials as in Example 8 except that the hardness of the compression rubber layer was changed to 95° and a belt sleeve (cross-linked sleeve) with a thickness of 8 mm was produced. The dimensions (thickness, section width, and outer circumference) of the obtained V-belt were also the same as those in Example 8.

[0314] (Drive pulley and driven pulley)

[0315] The dimensions are the same as those of Example 8 (minimum pitch circle diameter, maximum pitch circle diameter, and distance between axes).

[0316] (LT coefficient, with lateral rigidity)

[0317] As a result, the LT coefficient of the V-belt with respect to the drive pulley was 12, and the belt lateral rigidity (P) was 1500 N / mm.

[0318] [Comparative Example 7]

[0319] (V-belt)

[0320] A V-belt (cut-edge toothed V-belt) was obtained by using the same materials as in Comparative Example 6 except that the rubber composition of the compressed rubber sheet (uncrosslinked rubber sheet) was changed to C3 (rubber hardness after crosslinking: 93°). The dimensions (thickness, section width, outer circumference) of the obtained V-belt were also the same as those in Comparative Example 6.

[0321] (Drive pulley and driven pulley)

[0322] The dimensions are the same as those of Comparative Example 6 (minimum pitch circle diameter, maximum pitch circle diameter, and axis distance).

[0323] (LT coefficient, with lateral rigidity)

[0324] As a result, the LT coefficient of the V-belt with respect to the drive pulley was 12, and the belt lateral rigidity (P) was 1000 N / mm.

[0325] [Reference Example 1]

[0326] A representative example of a belt mechanism of a continuously variable transmission for a scooter rather than a bicycle (a belt mechanism having a belt thickness of 8 mm, the same as that of Example 1) was used as Reference Example 1 for comparison with Example 1, and a V-belt, a driving pulley, and a driven pulley were manufactured.

[0327] (V-belt)

[0328] A V-belt (trimmed-edge toothed V-belt) was obtained by using the same materials as in Example 1, except that the core was changed to A2 (PET core) and the rubber composition of the compressed rubber sheet (uncrosslinked rubber sheet) and the stretched rubber sheet (uncrosslinked rubber sheet) was changed to C2 (rubber hardness after crosslinking 89°). The belt sleeve (crosslinked sleeve) with a thickness of 8 mm was produced. The dimensions of the obtained V-belt were as follows: the belt thickness (H) was 8 mm, the belt section width (Wp) was 18.9 mm, and the belt outer circumference (BOC) was 750 mm.

[0329] (Drive pulley and driven pulley)

[0330] When the minimum pitch circle diameter (d1) was set to 55 mm and the maximum pitch circle diameter (d2) was set to 120 mm and the above-mentioned V-belt was used, the distance between the axes became 229 mm.

[0331] (LT coefficient, with lateral rigidity)

[0332] As a result, the LT coefficient of the V-belt with respect to the drive pulley was 5.9, and the belt lateral rigidity (P) was 600 N / mm.

[0333] [Evaluation with organizations: items, methods, and standards]

[0334] For each of the test pieces shown in Tables 5 to 11, in order to determine whether a belt mechanism (particularly a V-belt) capable of solving the problem of the present application was obtained, compactness, transmission performance (slip ratio), and durability were verified.

[0335] [Compactness]

[0336] (Judgment criteria)

[0337] In consideration of space and weight constraints, whether the belt mechanism is compact can be determined from the viewpoint of whether it can be compactly formed so as to be mounted on a bicycle continuously variable transmission designed specifically for bicycle use.

[0338] As a judgment of compactness, the dimensions of each part of the belt mechanism are used as an indicator. When all the following conditions (a) to (c) related to the dimensions of each part of the "drive pulley and the driven pulley" are satisfied and all the following conditions (d1) and (e) to (f) related to the dimensions of each part of the "V-belt" are satisfied, it is evaluated that the belt mechanism can be compactly formed in a manner that allows it to be mounted on a continuously variable transmission for a bicycle, and judgment a is made.

[0339] When all the following conditions (a) to (c) related to the dimensions of each part of the "driving pulley and the driven pulley" are satisfied and all the following conditions (d2) and (e) to (f) related to the dimensions of each part of the "V-belt" are satisfied, it is evaluated as slightly poor from the perspective of being compactly formed in a manner that allows the belt mechanism to be mounted on a continuously variable transmission for a bicycle, and is judged as b.

[0340] If none of the following conditions (a) to (c) related to the dimensions of each part of the "driving pulley and the driven pulley" and the following conditions (d2) and (e) to (f) related to the dimensions of each part of the "V-belt" are satisfied, and if the following condition (d1) related to the dimensions of each part of the "V-belt" is also not satisfied, it is evaluated that the belt mechanism cannot be compactly formed in a manner that allows it to be mounted on the continuously variable transmission for a bicycle, and judgment is made as c.

[0341] From the viewpoint of suitability for actual use in this application (compactness of the belt mechanism), the belt mechanisms in the a and b determinations were set to pass levels.

[0342] Dimensions of each part of the "driving pulley and driven pulley" (a) Minimum pitch diameter (d1) is 40 to 45 mm (b) Maximum pitch diameter (d2) is 70 to 80 mm (c) The distance between axes is 90 to 200 mm

[0343] Dimensions of various parts of "V-belt" (d1) Belt thickness (H) is 6 to 8 mm (d2) Belt thickness (H) exceeds 8 mm and is less than 9 mm (e) Section width (Wp) is 9 to 14 mm (f) Outer circumference (BOC) 360 to 610 mm

[0344] [Transmission performance (slip ratio)]

[0345] (Test name) Transmission performance (slip ratio) measurement test

[0346] (Testing machine)

[0347] Experimental use Figure 7 Biaxial travel testing machine with pulley layout shown.

[0348] The test machine is configured to have a driving pulley and a driven pulley having the same (fixed) V-groove width but different outer diameters, and can measure the transmission performance (slip ratio) under the speed change condition (i.e., the use condition in which the maximum torque is obtained in the state of shifting to the lowest speed side) in which the pitch circle diameter of the driving pulley is the smallest (d1 in Tables 5 to 11) and the pitch circle diameter of the driven pulley is the largest (d2 in Tables 5 to 11) based on the prescribed inter-axial distance (described in Tables 5 to 11).

[0349] (Test method)

[0350] Before and after the durability performance test described below, a transmission performance (slip ratio) measurement test was performed by the following method.

[0351] First, the V-belt of each test piece was wound so as to fit between the V grooves of the driving pulley and the driven pulley. Then, at room temperature, the distance between the shafts was set to a predetermined distance (described in Tables 5 to 11), and the V-belt was run from a no-load state with a shaft load of 600N (constant) applied to the driven shaft and a rotation speed of the driving shaft of 2000rpm (constant). The rotation speed (rpm) of the driven pulley was measured by a detector when a maximum torque (load) of 10Nm was input to the driving shaft immediately after the running, and the slip ratio was calculated according to the following formula.

[0352] Table 4 shows the rotation speeds of the drive pulley and the driven pulley when there is no load and the rotation speed of the drive pulley when there is a load in the measurement.

[0353] Slip rate (%) = [(K2-K1) / K1] × 100

[0354] [In the formula, K1 = R1 / N1, K2 = R2 / N2, R1 represents the speed of the driving pulley during no-load operation (rpm), N1 represents the speed of the driven pulley during no-load operation (rpm), R2 represents the speed of the driving pulley during loaded operation (rpm), and N2 represents the speed of the driven pulley during loaded operation (rpm).]

[0355] [Table 4]

[0356] (Judgment criteria)

[0357] The slip ratio is used as an index to judge the transmission performance of the belt (the smaller the slip ratio, the more the slip is suppressed and the necessary transmission force can be ensured). The slip ratio value [the larger value before and after running (before running, after running for 400 hours)] (%) is,

[0358] The case below 3.5% is set as judgment a.

[0359] The case where the percentage is more than 3.5% and less than 5% is considered as judgment b.

[0360] If it exceeds 5%, or if the drive shaft is completely slipped (full slip state) before a predetermined maximum torque (load) is input to the drive shaft, the situation where measurement cannot be performed under a predetermined load (measurement cannot be performed) is judged as c.

[0361] From the viewpoint of suitability for actual use in this application (transmission performance of the V-belt), belts with evaluations a and b were considered to be at an acceptable level.

[0362] If the transmission performance (slip ratio) measured before running of the durability performance test described later was determined as c, the durability performance test was not performed.

[0363] [Durability]

[0364] (Test name) Durability test

[0365] (Testing machine)

[0366] Experimental use Figure 8 Biaxial travel testing machine with pulley layout shown.

[0367] The test machine is configured to have a driving pulley and a driven pulley having the same (fixed) V-groove width but different outer diameters, and can confirm the durability performance (presence or absence of belt failure) under the speed change condition (i.e., the use condition with the minimum torque when the speed is changed to the highest speed side) in which the pitch circle diameter of the driving pulley is the largest (d2 in Tables 5 to 11) and the pitch circle diameter of the driven pulley is the smallest (d1 in Tables 5 to 11) based on the prescribed inter-axis distance (described in Tables 5 to 11).

[0368] (Test method)

[0369] The V-belt of each test piece was wound so as to be inserted between the V grooves of the driving pulley and the driven pulley. At room temperature, the distance between the shafts was set to a predetermined distance (described in Tables 5 to 11), and the V-belt was driven for 400 hours [equivalent to an actual running distance (bicycle, speed of 25 km / h) of 10,000 km] with a torque (load) of 2 Nm input to the driving shaft at 2000 rpm (constant) while a shaft load of 400 N (constant) was applied to the driven shaft. The belt was visually observed and the presence or absence of abnormalities such as cracks (especially cracks in the cog valley) and peeling, and the time until the belt broke were evaluated based on the following criteria.

[0370] (Judgment criteria)

[0371] As a measure of the belt's durability,

[0372] The case where the vehicle has traveled for 400 hours without any abnormalities such as cracks or peeling is considered as judgment a.

[0373] The case where a small amount of cracking or peeling is observed after running for 400 hours (to a degree that does not affect performance) is judged as b.

[0374] A case where an abnormality (crack, peeling) that impairs the performance occurs during travel or at the time of 400 hours of complete travel and the belt is considered to be damaged is judged as c.

[0375] From the viewpoint of suitability for actual use in this application (durability performance of the V-belt), belts with the ratings a and b were considered to be at a pass level.

[0376] (Comprehensive judgment)

[0377] The criteria for comprehensive evaluation (grading) of belt mechanisms that can solve this problem are as follows based on the evaluation results of the above three evaluation items (compactness, transmission performance (slip ratio), and durability performance).

[0378] Rank A: When all the evaluation items are judged as a, it is judged that there is no problem in practical use and it is set as the best rank.

[0379] Rank B: In the above evaluation items, there is no c judgment, but even if there is a b judgment, there is no problem in practical use, but it is set to a slightly poor rank.

[0380] Level C: If even one of the above evaluation items is judged as c, the solution to this problem is considered insufficient (failed).

[0381] [Verification results]

[0382] The verification results are shown in Tables 5 to 11.

[0383] In the following comparative verification between the various test pieces, it is known that the conditions shown below have relatively little effect on the belt lateral rigidity and belt performance [transmission performance (slip ratio), durability performance], so the levels are not changed and fixed (constant) conditions are used.

[0384] (Fixed conditions)

[0385] [V-belt]

[0386] Hardness of the adhesive rubber layer, hardness of the tensile rubber layer, belt section width, belt circumference length

[0387] [Drive pulley and driven pulley]

[0388] Maximum pitch diameter, distance between axes

[0389] [Table 5]

[0390] (Examples 1 and 2)

[0391] In a belt mechanism using a V-belt having a core wire using aramid fiber, a compression rubber layer with a hardness of 95°, and a constant belt thickness of 8 mm, the minimum pitch diameter of the pulley was varied for comparison.

[0392] As a condition of use (precondition), the minimum pitch diameter of the pulley that satisfies both compactness (spatial constraints) and the permissible range of the variable speed belt mechanism is limited to the range of 40 to 45 mm. It was found that within this range, if the minimum pitch diameter of the pulley increases, there is a tendency for the LT coefficient to decrease and the slip rate to decrease. Since the V-belts of both (Examples 1 and 2) are of the same form, there is no difference in the lateral rigidity of the belts (both 2000 N / mm), and under these conditions, the specified (qualified level) belt performance [transmission performance (slip rate), durability performance] (a judgment or b judgment) can be ensured.

[0393] Specifically, when the minimum pitch circle diameter of the pulley is 45 mm (Example 1), the transmission performance (slip ratio) and the durability performance are both judged as a (level A in the comprehensive judgment), but when the minimum pitch circle diameter of the pulley is 40 mm (Example 2), compared with the case where the minimum pitch circle diameter of the pulley is 45 mm (Example 1), the durability performance is judged as a similar a, but since the LT coefficient is slightly larger at 12, the transmission performance (slip ratio) is judged as b (also level B in the comprehensive judgment).

[0394] Based on the above results, it can be said that in order to achieve both compactness and belt performance [transmission performance (slip ratio), durability performance], the minimum pitch diameter of the pulley is preferably in the range of 40 to 45 mm, and most preferably 45 mm.

[0395] [Table 6]

[0396] (Examples 1 and 3)

[0397] Based on the belt mechanism of Example 1 (hardness of the compression rubber layer 95°, belt thickness 8 mm, minimum pitch diameter of the pulley 45 mm), the fiber constituting the core wire (aramid fiber) was changed for comparison.

[0398] In Example 3, in which a PET core wire (index 43) having a lower tensile elastic modulus than an aramid core wire was used, the durability performance was judged as a level equivalent to that of the case in which an aramid core wire was used (Example 1), but since the belt lateral rigidity was slightly reduced, the transmission performance (slip ratio) was judged as b (also grade B in the overall judgment).

[0399] [Table 7]

[0400] (Examples 1, 4, Comparative Examples 1-2)

[0401] Based on the belt structure of Example 1 (aramid core wire, belt thickness 8 mm, minimum pitch diameter of pulley 45 mm), the hardness of the compression rubber layer was changed to 95° for comparison.

[0402] As the hardness of the compression rubber layer increases, the belt lateral rigidity increases and the slip rate decreases. However, if the belt lateral rigidity becomes too large, the durability performance (crack resistance) tends to be poor.

[0403] Specifically, in Comparative Example 1 in which the hardness of the compression rubber layer was reduced to 93° relative to Example 1, the lateral rigidity of the belt was too small, 1000 N / mm, and the transmission performance (slip ratio) before the endurance travel was not measurable [a state in which the belt completely slipped (at a torque of 8 Nm) before the specified (10 Nm) maximum torque was input to the drive shaft], resulting in a judgment of c (also a level C in the comprehensive judgment). In Comparative Example 2 in which the hardness of the compression rubber layer was increased to 97° (an upper limit level of the rubber hardness that satisfies the manufacturing quality of the belt) relative to Example 1, the transmission performance (slip ratio) was a judgment, but since the lateral rigidity of the belt became too large, 2700 N / mm, the flexibility of the belt was excessively reduced, and cracks (cog valleys) were generated during travel, resulting in a judgment of c in the endurance performance (also a level C in the comprehensive judgment).

[0404] Furthermore, the durability of the belt (particularly crack resistance) is also affected by the bendability of the belt (the better the bendability, the better the crack resistance), and the belt thickness also has an influence on the bendability of the belt.

[0405] Therefore, in order to confirm its influence, Example 4 is an example in which the belt thickness is reduced to 7 mm under the condition that the hardness of the compression rubber layer is kept constant at 97° relative to the V-belt of Comparative Example 2, but since the bending property of the belt is slightly improved, the durability performance is judged as a, which is the same as that of Example 1 (also grade A in the comprehensive judgment).

[0406] From the above results, it can be said that the preferred range of the hardness of the compression rubber layer of the V-belt is 95° or more and 97° or less in terms of ensuring the belt performance [transmission performance (slip ratio), durability performance].

[0407] [Table 8]

[0408] (Examples 1, 5-6, Comparative Example 3)

[0409] Comparison was performed based on the belt structure of Example 1 (aramid core wire, compression rubber layer hardness 95°, minimum pitch diameter of pulley 45 mm), but with the belt thickness changed by 8 mm.

[0410] As the belt thickness increases, compactness is impaired, but the LT coefficient decreases, the belt lateral rigidity increases, and there is a tendency for the slip ratio to decrease.

[0411] Specifically, relative to Example 1, in Example 5 in which the belt thickness was reduced to 7 mm, the transmission performance (slip ratio) was judged as b, and the durability performance was judged as a, which was Grade B, which was a qualified level. However, in Comparative Example 3 in which the belt thickness was reduced to 6 mm, the LT coefficient was 12, and the lateral rigidity of the belt was too small, being 800 N / mm. The transmission performance (slip ratio) before the endurance travel was unmeasurable (in a state of full slip at a torque of 8 Nm), and was judged as c (also Grade C in the comprehensive judgment).

[0412] Compared with Example 1, in Example 6 in which the belt thickness was increased to 9 mm, the compactness became b-judgment, but the LT coefficient decreased to 8.1, and the belt lateral rigidity was increased to 2500 N / mm, and the transmission performance (slip ratio) and durability performance were both a-judgment (comprehensive judgment was level B).

[0413] Based on the above results, it can be said that in terms of achieving both compactness and belt performance [transmission performance (slip ratio), durability performance], the belt thickness is preferably in the range of 7 to 9 mm, more preferably in the range of 7 to 8 mm, and most preferably 8 mm.

[0414] [Table 9]

[0415] (Examples 6-7, Comparative Examples 4-5)

[0416] In addition, in addition to Example 6, even under other conditions where the LT coefficient was at a level of 8 (conditions where the belt thickness was 9 mm and the minimum pitch diameter of the pulley was constant at 45 mm), the influence on the belt performance was confirmed.

[0417] Comparative Example 4 is an example in which the hardness of the compression rubber layer is increased to 97° relative to the belt mechanism of Example 6 (aramid core wire, belt thickness 9 mm, minimum pitch diameter of the pulley 45 mm). However, at the same LT coefficient level of 8, the lateral rigidity of the belt becomes too large, 3000 N / mm, and the transmission performance (slip rate) is the same a judgment, but the durability performance is grade C in the c judgment due to the excessive reduction in the flexibility of the belt.

[0418] Example 7 is an example in which the hardness of the compression rubber layer is reduced to 93° in contrast to Example 6. However, since the LT coefficient is the same level of 8 and the belt lateral rigidity is reduced to 1500 N / mm, the slip ratio value increases and the transmission performance is judged as b. However, since the belt has good bending properties, the durability performance is judged as the same a, which is grade B.

[0419] Comparative Example 5 is an example in which the core wire is changed to a PET core wire relative to Example 7. However, at the same LT coefficient level of 8, the lateral rigidity of the belt is too small, at 1100 N / mm, and the transmission performance (slip rate) before endurance travel cannot be measured (in a state of full slip at a torque of 8 Nm), and is judged as c (also grade C in the comprehensive judgment).

[0420] Based on the above results, compared with the case of small motorcycles (LT coefficient is about 4 to 8), even if the LT coefficient is too large, as long as the belt lateral rigidity is maintained in the range of 1500 to 2500N / mm, the belt performance [transmission performance (slip ratio), durability performance] can be ensured.

[0421] [Table 10]

[0422] (Examples 8 to 9, Comparative Examples 6 to 7)

[0423] In addition to Example 2 and Comparative Example 3, the influence on the belt performance was also confirmed under other conditions at the LT coefficient level of 12 (conditions where the belt thickness was 8 mm and the minimum pitch diameter of the pulley was 40 mm).

[0424] Comparative Example 6 is an example in which the belt structure of Comparative Example 2 (aramid core wire, compression rubber layer hardness 97°, belt thickness 8mm) is unchanged, and the minimum pitch diameter of the pulley is reduced to 40mm. However, since the lateral rigidity of the belt is maintained at an excessively large 2700N / mm, the LT coefficient is slightly increased to 12, so the transmission performance (slip ratio) becomes a b judgment, and the durability performance is the same as the c judgment, which is grade C.

[0425] Example 8 is an example in which the core wire is changed to a PET core wire compared to Comparative Example 6. However, since the LT coefficient is the same level of 12, the lateral rigidity of the belt is slightly reduced to 2500 N / mm, so the slip rate value is slightly increased (the transmission performance is the same b judgment), the bendability of the belt is slightly improved, and the durability performance is slightly improved (b judgment), which is grade B.

[0426] Example 9 is an example in which the hardness of the compression rubber layer is changed to 95° relative to Example 8. However, since the LT coefficient is the same level of 12, the lateral rigidity of the belt is slightly reduced to 1500 N / mm, so the slip rate value is slightly increased (the transmission performance is the same b judgment), but the bending property of the belt is further improved, so the durability performance is slightly improved, which is a judgment and is grade B.

[0427] Comparative Example 7 is an example in which the hardness of the compression rubber layer is reduced to 93° relative to Comparative Example 6, but the LT coefficient is the same level of 12, and the belt lateral rigidity is too small, at 1000 N / mm. The transmission performance (slip rate) before endurance travel cannot be measured (a state of full slip at a torque of 8 Nm), and is judged as c (also grade C in the comprehensive judgment).

[0428] Based on the above results, compared with the case of small motorcycles (LT coefficient is about 4 to 8), it can be said that even if the LT coefficient is too large, as long as the belt lateral rigidity is maintained in the range of 1500 to 2500N / mm, the belt performance [transmission performance (slip ratio), durability performance] can be ensured.

[0429] [Table 11]

[0430] (Example 1, Reference Example 1)

[0431] A representative example of a belt mechanism provided in a continuously variable transmission for a scooter, which is equivalent to the belt mechanism of Example 1 (belt thickness 8 mm), is referred to as Reference Example 1.

[0432] In Reference Example 1 (for scooters), the minimum pitch diameter of the driving pulley and the driven pulley is larger than that of Example 1 (for bicycles), which is 55 mm (furthermore, the maximum pitch diameter is 120 mm, and the distance between the axes is 229 mm), so the LT coefficient is significantly reduced to 5.9 when the belt thickness (8 mm) and the maximum torque (10 Nm) are constant. Therefore, for the V-belt, the core wire is PET fiber, the hardness of the compression rubber layer is 89°, and even if the lateral rigidity of the belt is too small, which is 600 N / mm, the belt performance [transmission performance (slip rate), durability performance] is also judged as a.

[0433] However, compactness is determined by C, and it is not possible to achieve both compactness and belt performance [transmission performance (slip ratio), durability] (C determination).

[0434] (Result)

[0435] From the results of Tables 5 to 11, it can be seen that the belt mechanisms of the embodiments are formed compactly compared with the case of a small motorcycle (LT coefficient is about 4 to 8) by appropriately designing the V-belt (core wire type, hardness of the compression rubber layer, belt thickness, etc.) and the drive pulley and the driven pulley (minimum pitch circle diameter, maximum pitch circle diameter, distance between axes) so as to be mounted on a continuously variable transmission for a bicycle, and the LT coefficient, which is an index (substitute characteristic) indicating "the ease of belt slippage", is too large at 8 to 12, and the pitch circle diameter of the drive pulley is the minimum (in the range of 40 to 45 mm). Even under severe use conditions such as insufficient friction transmission capacity and extremely easy to induce slippage between the drive pulley and the V-belt As for the lower (pulley layout, load), it is possible to ensure a sufficiently high level compared to the case of a small motorcycle where the belt lateral rigidity is 1500~2500N / mm, which is an indicator (substitute characteristic) of the lateral pressure resistance, that is, the "difficulty of buckling deformation relative to the axial load (lateral pressure)" (the size of the change in exposed height). As a result, not only the durability performance is ensured (no significant abnormality is observed until the target end of 400 hours, and the vehicle can travel smoothly), but also the slip between the drive pulley (minimum pitch diameter) and the belt can be suppressed with respect to the transmission performance (slip rate before and after the durability performance test), thereby achieving the effect of ensuring the necessary transmission force (slip rate of less than 5%).

[0436] Although the present invention has been described in detail and with reference to specific embodiments, it is apparent to one skilled in the art that various modifications and variations can be added without departing from the spirit and scope of the present invention.

[0437] This application is based on Japanese Patent Application No. 2022-073123 filed on April 27, 2022 and Japanese Patent Application No. 2023-065626 filed on April 13, 2023, the contents of which are incorporated herein by reference.

[0438] Description of symbols 1 Belt mechanism 2 Drive pulley 21 Fixed pulley 22 Movable pulley 3 Driven pulley 31 Fixed pulley 32 Movable pulley 4 V-belts (cut-edge toothed V-belts).

Claims

1. A belt mechanism for a bicycle continuously variable transmission, comprising: The driving pulley and the driven pulley are composed of a pair of pulleys that are free to approach and separate in the direction of the rotation axis; and A V-belt is wound between the driving pulley and the driven pulley. in, Under the use condition that the maximum torque is obtained when the speed is shifted to the lowest speed side, the LT coefficient of the V-belt with respect to the driving pulley is in the range of 8 to 12, The belt lateral rigidity in the V-belt exposed height variation measurement test is in the range of 1500 to 2500 N / mm.

2. The belt mechanism of the bicycle continuously variable transmission according to claim 1, wherein: The minimum pitch diameter of the driving pulley is in the range of 40 to 45 mm. The V-belt has a thickness in the range of 7 to 8 mm.

3. The belt mechanism of the bicycle continuously variable transmission according to claim 1 or 2, wherein: The belt mechanism is mounted on a continuously variable transmission, and the continuously variable transmission is connected to an auxiliary power source of a bicycle equipped with an auxiliary power source.

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