Search

EP-4379235-B1 - TOOTHED BELT AND MANUFACTURING METHOD THEREFOR

EP4379235B1EP 4379235 B1EP4379235 B1EP 4379235B1EP-4379235-B1

Inventors

  • OSAKI SUSUMU
  • HEMMI YUSUKE
  • MIZUMOTO Takumi

Dates

Publication Date
20260506
Application Date
20220722

Claims (7)

  1. A toothed belt (1) comprising: a back portion (1c) in which a tension member (5) extending along a belt circumferential direction is embedded; a plurality of tooth portions (1a) formed on an inner circumferential surface of the back portion (1c) with an interval in the belt circumferential direction; a back rubber layer (6) formed on a belt outer circumference side with respect to the tension member (5); and a first rubber layer (3) and a second rubber layer (4) formed on a belt inner circumferential side with respect to the tension member (5), wherein an inner circumferential belt surface is formed of a tooth fabric (2), the back portion (1c) comprises the back rubber layer (6), and the tooth portion (1a) comprises the tooth fabric (2), the first rubber layer (3) formed along the tooth fabric (2), and the second rubber layer (4) interposed between the first rubber layer (3) and the tension member (5); characterized in that an elastic modulus of the first rubber layer (3) is larger than an elastic modulus of the second rubber layer (4).
  2. The toothed belt (1) according to claim 1, wherein an area proportion of the first rubber layer (3) is 10 area% to 80 area% with respect to a total area of the first rubber layer (3) and the second rubber layer (4) in a cross-sectional view in the belt circumferential direction.
  3. The toothed belt (1) according to claim 1 or 2, wherein a tensile elastic modulus of the first rubber layer (3) is 0.6 MPa to 20 MPa, and a tensile elastic modulus of the second rubber layer (4) is 0.5 MPa to 5 MPa.
  4. The toothed belt (1) according to any one of claims 1 to 3, wherein a tensile elastic modulus of the first rubber layer (3) is 1.2 times to 4 times a tensile elastic modulus of the second rubber layer (4).
  5. The toothed belt (1) according to any one of claims 1 to 4, wherein the first rubber layer (3) comprises a first crosslinked rubber composition comprising a first rubber component, a first crosslinking agent, and a first co-crosslinking agent, the second rubber layer (4) comprises a second crosslinked rubber composition comprising a second rubber component, a second crosslinking agent, and a second co-crosslinking agent, the first rubber component comprises a first composite polymer comprising a hydrogenated nitrile rubber and an unsaturated carboxylic acid metal salt, the second rubber component comprises a second composite polymer comprising a hydrogenated nitrile rubber and an unsaturated carboxylic acid metal salt, a proportion of the first co-crosslinking agent with respect to 100 parts by mass of the first rubber component is 1 part by mass to 40 parts by mass, and a proportion of the second co-crosslinking agent with respect to 100 parts by mass of the second rubber component is 0.2 parts by mass to 25 parts by mass.
  6. The toothed belt (1) according to claim 5, wherein the first crosslinked rubber composition further comprises a first reinforcing inorganic filler, the second crosslinked rubber composition further comprises a second reinforcing inorganic filler, a proportion of the first composite polymer in the first rubber component is 80 mass% or more, a proportion of the second composite polymer in the second rubber component is 30 mass% or more, the first crosslinking agent comprises a first organic peroxide, and a proportion of the first organic peroxide with respect to 100 parts by mass of the first rubber component is 1 part by mass to 20 parts by mass, the second crosslinking agent comprises a second organic peroxide, and a proportion of the second organic peroxide with respect to 100 parts by mass of the second rubber component is 0.5 parts by mass to 5 parts by mass, a proportion of the first reinforcing inorganic filler with respect to 100 parts by mass of the first rubber component is 10 parts by mass or less, and a proportion of the second reinforcing inorganic filler with respect to 100 parts by mass of the second rubber component is 10 parts by mass or less.
  7. A method for manufacturing a toothed belt (1) according to any one of claims 1 to 6, the method comprising: a preforming step of preparing a preformed body in which a tooth fabric precursor for forming a tooth fabric (2), an uncrosslinked rubber sheet for forming a first rubber layer (3), and an uncrosslinked rubber sheet for forming a second rubber layer (4) are laminated.

Description

TECHNICAL FIELD The present invention relates to a rubber toothed belt (or rubber toothed belt coated with tooth fabric) which meshes with a toothed pulley and which is useful for transmitting power in synchronization with a general industrial machine or the like under a high load condition, and a manufacturing method therefor. BACKGROUND ART A power-transmission belt that transmits power is roughly classified into a frictional power-transmission belt and a synchronous power-transmission belt. Examples of the frictional power-transmission belt include a flat belt, a V belt, and a V-ribbed belt, and examples of the synchronous power-transmission belt include a toothed belt. The toothed belt includes a back portion in which a tension member is embedded substantially parallel to a belt circumferential direction, tooth portions arranged at a predetermined interval in the belt circumferential direction, and a tooth fabric covering a surface of the tooth portions. The toothed portions of the toothed belt transmit power by being fitted to a pulley having grooves facing the toothed portions. Slipping does not occur between the toothed belt and the pulley, and the toothed belt can reliably transmit power even with a high load. In recent years, there has been an increasing number of examples used for industrial machine, internal combustion engines of automobiles, and rear-wheel drive of motorcycles, and in particular, with miniaturization of machines, a toothed belt coping with miniaturization is also required (to cope with a small-diameter pulley, and to reduce a width). In a case where a miniaturized toothed belt is used in the same environment as a conventional large-sized toothed belt, a higher load acts on the toothed belt. Therefore, a toothed belt coping with miniaturization and having high durability capable of withstanding use under a condition where a higher load acts is required. An important factor for the durability of the toothed belt is rigidity (deformation resistance) of the tooth portion. In a process of meshing with the toothed pulley, repeated deformation of the tooth portion due to contact with the toothed pulley leads to a failure such as meshing failure due to tooth skipping (jumping) or tooth chipping due to a crack in a tooth root portion. The tooth chipping is a failure form in which the tooth portion drops from a belt main body and a mechanism thereof is considered to be that in a process in which stress acts on a root of the tooth portion intensively due to repeated deformation of the tooth portion, a minute crack is first generated in the tooth root, and then the crack is grown. In particular, in a case where the toothed belt is used under a condition where a high load acts, the stress concentrated on the tooth root portion becomes particularly large, and a crack is generated from the tooth root as a starting point, which easily leads to tooth chipping. Therefore, it is necessary to increase the rigidity in order to prevent deformation of the tooth portion. On the other hand, in a case where the rigidity of the tooth portion is increased, bending rigidity of the belt is also increased, and bendability is deteriorated. In a case where the toothed pulley is miniaturized (reduced in diameter) along with the miniaturization of the machine, high bendability (flexibility) is also required so that the toothed belt is wound around the small-diameter pulley to provide good meshing property. In order to enhance the bendability, enhancing the rigidity of the tooth portion is not suitable. That is, in the toothed belt, the rigidity (deformation resistance) and the bendability (flexibility) of the tooth portion are in a contradictory relation and are difficult to be compatible with each other, and thus a balanced method for implementing the compatibility is required. JP2011-85160A discloses a toothed belt in which an intermediate canvas having an elastic modulus of 100 GPa or more in a belt width direction is embedded inside a belt main body in which tooth portions and tooth bottom portions are alternately provided along a longitudinal direction on one surface, and describes, as the tooth portion, a tooth portion which is formed by a core rubber layer constituting the inside of the tooth portion and tooth rubber layers disposed along an outer circumference of the tooth portion and laminated on an one surface side of the core rubber layer, and in which a modulus of the core rubber layer is higher than a modulus of the tooth rubber layer. In addition, WO2011/045984 discloses a toothed belt including a belt main body in which tooth portions and tooth bottom portions are alternately provided along a longitudinal direction on one surface, and describes as the belt main body portion, a belt main body portion including a tooth rubber layer disposed along an outer circumference of the tooth portions and a core rubber layer constituting an inside of the tooth portions, in which the core rubber layer has a high