V-ribbed power transmission belt

Endless belt power transmission systems or components – Friction drive belt

Reexamination Certificate

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Details

C474S238000, C474S260000, C428S337000

Reexamination Certificate

active

06176799

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to power transmission belts and, more particularly, to a V-ribbed power transmission belt with a controlled belt slip ratio.
2. Background Art
A conventional V-ribbed belt has a body with an inside and an outside and load carrying members embedded in a cushion rubber layer. A canvas cover is applied on a surface outwardly of the cushion rubber layer, with a plurality of laterally spaced ribs defined on the body inside of the cushion rubber layer. This belt construction has been widely used to drive automobile accessories, such as air compressors, alternators, and the like. For this type of belt to efficiently transmit power to and from cooperating components, it is important to have a relatively low slip ratio between the belt and a cooperating pulley. The belt slip ratio can be decreased by increasing the tension on the belt.
By increasing the tension on the belt, the dry heat shrinkage stress of the belt is increased. However, the dry heat shrinkage ratio and the shrinkage of the belt length over time increase.
SUMMARY OF THE INVENTION
The present invention has as an objective the ability to address the above problems and provide a V-ribbed belt with a relatively low belt slip ratio and one which has a good life expectancy.
In one form of the invention, a power transmission belt is provided having a body with a length, an inside, an outside, laterally spaced sides, and at least one rib. The body has a compression section, a tension section, and a load carrying element between the inside and outside of the body and extending in a lengthwise direction. The load carrying member is made from twisted polyester fiber filaments having an ethylene-2,6-naphthalate component and a denier of 4,000-8,000. The belt requires a stress of at least 500 N per rib to effect elongation of the belt by 3%. The belt has a dry heat shrinkage stress between 100 N and 200 N after an initial load of 147 N is applied to the belt and the belt is allowed to reside in an atmosphere at a temperature of 100° C. for 30 minutes.
In one form, the body has a plurality of laterally spaced ribs on at least one of the inside and outside thereof.
The body may have a cushion rubber layer in which the load carrying element is embedded.
In one form, the ribs are defined in the compression section by at least one of hydrogenated nitrile rubber with a hydrogenation rate of at least 80%, chloroprene rubber, natural rubber, chlorosulfonated polyethylene rubber (CSM), alkylated chlorosulfonated polyethylene (ACSM), and styrene-butadiene rubber (SBR).
Reinforcing fibers may be embedded in rubber in the compression section.
These fibers may be at least one of nylon 6, nylon 66, polyester, cotton, and aramid, with a length between 1 and 20 mm and may be present in an amount of 1-30 parts by weight per 100 parts by weight of rubber.
The fibers may be adhesive treated with at least one of an epoxy compound and isocyanate compound.
The load carrying element may be a cord with filaments that are upper twisted between 10 and 23 times per 10 cm and lower twisted between 17 and 38 times per 10 cm.
In one form, the ethylene-2,6-naphthalate is formed by polycondensing at least one of naphthalene-2,6-dicarboxylic acid and its ester-forming derivative in the presence of a catalyst.
The load carrying element may be treated with at least one of an epoxy compound and an isocyanate compound.
After treating the load carrying element with at least one of an epoxy compound and an isocyanate compound, the load carrying element may be dried and treated with an RFL solution.
After treatment with the RFL solution, the load carrying element may be drawn from 1 to 3%.
A canvas layer may be provided on one of the inside and outside of the body.
The invention also contemplates a method of forming a power transmission belt, which method includes the steps of: twisting a plurality of polyester fiber filaments having an ethylene-2,6-naphthalate component together to define a load carrying cord having a denier of 4,000-8,000; treating the load carrying cord with at least one of an epoxy compound, an isocyanate compound, and an RFL solution; drawing the cord after treating the cord in a controlled temperature environment; embedding the cord into a body; and forming the body to define a power transmission belt having at least one rib. The treating and drawing steps are controlled so that (a) a stress of at least 500 N per rib is required to effect elongation of the belt by 3% and (b) the belt has a dry heat shrinkage stress between 100 N and 200 N after an initial load of 147 N is applied to the belt and the belt is allowed to reside in an atmosphere at a temperature of at least 100° C. for 30 minutes.
The drawing step may involve drawing the cord to between 1 and 3% at a temperature from 210° to 260° C. for 30 to 600 seconds.
The step of treating the load carrying cord may involve the steps of pre-treating the load carrying cord with at least one of an epoxy compound and an isocyanate compound, drying the at least one of the epoxy compound and the isocyanate compound, and thereafter treating the load carrying cord with an adhesive having an RFL solution.
The step of drying the at least one of the epoxy compound and the isocyanate compound may include the step of drying the at least one of the epoxy compound and the isocyanate compound at a temperature of 160 to 200° C. for 30 to 600 seconds.
The drawing step may involve drawing the cord from 1 to 3% with the cord maintained in an atmosphere at a temperature of 210° to 260° C. for 30 to 600 seconds.
The process may further include forming multiple ribs on the body.
The method may still further include the steps of embedding reinforcing fibers in the body and applying a canvas layer to the body.


REFERENCES:
patent: 4577362 (1986-03-01), Tanaka et al.
patent: 4812360 (1989-03-01), Utsumi
patent: 4904232 (1990-02-01), Kitahama et al.
patent: 5037360 (1991-08-01), Fujiwara et al.
patent: 5116286 (1992-05-01), Kinoshita et al.
patent: 5387160 (1995-02-01), Nakajima et al.
patent: 5413538 (1995-05-01), Mishima
patent: 5536214 (1996-07-01), Akita et al.

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