Endless belt power transmission systems or components – Positive drive belt – Belt formed of rigid links
Patent
1994-12-19
1996-10-08
Schoeppel, Roger J.
Endless belt power transmission systems or components
Positive drive belt
Belt formed of rigid links
F16G 1302
Patent
active
055625584
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a chain used for high-accuracy transmission and transportation which requires a low friction and a high wear resistance, and more particularly, to a chain provided with pins freely rotatable with respect to link plates.
BACKGROUND ART
In roller chains and bush chains which have conventionally been used for transmission and transportation, pins and bushes are fixed to outside link plates and inside link plates, respectively. Since the pins and bushes are in sliding contact with one another, they are subject to high friction and heavy wear to cause significant elongation of the chain as well as power loss. Thus, this type of chain is not considered to be suitable for such use that requires high-accuracy positioning. Also, the bushes and rollers significantly wear and make loud noises by the engagement of the chain and a sprocket. As one of the countermeasures to reduce friction and wear, there is known an arrangement such that needle roller bearings are interposed between the pins and the bushes. In this arrangement, however, the interposition of needle rollers causes a problem such as a decrease of the pin diameter and a reduction of the load-carrying capacity. Some chains for heavy-load suspension have no bushes. However, as such pins are directly fitted in link plates, these chains are extremely disadvantageous in terms of friction resistance and wear resistance in transmission or transportation service, and furthermore, the pins have no tooth face for drive.
DISCLOSURE OF THE INVENTION
The present invention provides a chain for transmission and transportation with low friction, high wear resistance, a large load-carrying capacity and low noise.
A conventionally used triple structure at pin-bush-roller structure, is replaced with a structure in which pins can rotate with low friction with respect to all link plates connecting the adjacent pins. Rolling bearings are suitable as bearings for this structure, but plain bearings may also be used if pins of a large diameter are adopted.
A chain according to one aspect of the present invention comprises a plurality of pins arranged parallel to one another at regular intervals and each having a tooth face to be directly in contact with a tooth face of a sprocket, a plurality of first link plates for connecting each of two adjacent pins, a plurality of second link plates for connecting each of two adjacent pins not connected by the first link plates, and bearings respectively attached to the first and second link plates for rotatably supporting the pins.
According to another aspect of the present invention, each pin is supported by at least one rolling bearing attached to one of the link plates and a plain bearing attached to the other link plate. The chain bends when it is brought into engagement with the sprocket through the rotation of the pins allowed by the rolling bearings due to the difference in frictional force between the plain bearings and the rolling bearings.
Tooth faces of the chain for an engagement with the sprocket teeth are formed on the outer peripheral surfaces of the pins or the outer rings of the rolling bearings. When the outer peripheral surfaces of the pins are used as the tooth faces, only half the number of rolling bearings and half the number of plain bearings are provided. When the outer rings of the rolling bearings are used as the tooth faces, a part of the outer peripheral surface of each rolling bearing is supported by a plain bearing, and a space to allow the entry of a sprocket tooth is provided on one side of each link plate with which the sprocket tooth face is to be engaged. The outer peripheral surface of the outer ring of the rolling bearing exposed to the space is used as a tooth face to be engaged with the sprocket tooth face. The engagement with the sprocket is made in the rolling contact without the use of rollers.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1a is a plan sectional view of a chain according to a first embodiment of the present invention, FIG. 1b is a c
REFERENCES:
patent: 690317 (1901-12-01), Renold
patent: 1598906 (1926-09-01), Dull
patent: 3074290 (1963-01-01), Eastep
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