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Title:
ROLLER CHAIN BUSHING
Document Type and Number:
WIPO Patent Application WO/2003/067119
Kind Code:
A2
Abstract:
A substantially cylindrical bushing (18) for a roller chain (10) formed from a substantially parallelogram blank (fig. 6), wherein the lateral sides (26) of the blank are obliquely related to the ends of the blank such that the rolling of the blank to form the cylindrically bushing results in a helical bushing seam-line (30).

Application Number:
PCT/IN2003/000001
Publication Date:
August 14, 2003
Filing Date:
January 03, 2003
Export Citation:
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Assignee:
L G BALAKRISHNAN & BROS LTD (IN)
International Classes:
F16G13/06; (IPC1-7): F16G/
Foreign References:
JPS5825840A1983-02-16
FR1381343A1964-12-14
US5697206A1997-12-16
US5857318A1999-01-12
US4751777A1988-06-21
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Claims:
CLAIMS
1. An improved roller chain assembly having a plurality of first and second sets of side links interconnected by pins and a substantially cylindrical bushing circumscribing each pin, the improvement comprising: said bushing having a longitudinal axis and a pair of opposite ends each lying in a plane wherein said longitudinal axis is substantially perpendicular to said planes; AND said bushing having a seam line intersecting said ends and obliquely related to said planes of said ends. The improved roller chain assembly stated in claim 1, further comprising said seam line having a helical configuration. The improved roller chain assembly stated in claim 1, further comprising said bushing fabricated from a metallic material.
2. 4 The improved roller chain assembly stated in claim 1, further comprising : said bushing fabricated from a substantially planar blank having a substantially parallelogram configuration defined by said ends and a pair of lateral sides wherein said lateral sides substantially engage one another to form said seam line.
3. 5 The improved roller chain assembly stated in claim 4 further comprising: said ends and said lateral sides of said parallelogram forming a substantially 12 degree angle.
4. 6 A method of forming a roller chain bushing from a substantially planar blank, wherein said blank is defined by a pair of opposite ends and lateral sides, the steps comprising : forming said ends substantially perpendicular to a longitudinal axis of said blank; forming said lateral sides parallel to each other and obliquely to said ends; AND creating a blank of a substantially parallelogram configuration and then rolling the blank in a direction parallel to said ends so that said lateral sides substantially engage one another to form a substantially cylindrical roller chain bushing having a helically configured seam line defined by said lateral sides.
5. 7 The method of forming a roller chain bushing stated in claim 6, the steps further comprising : fabricating said blank from a metallic material.
6. 8 The method of forming a link chain bushing stated in claim 6, the steps further comprising; establishing a 12degree angle between said ends and said lateral sides.
7. 9 An improved the roller chain assembly as described in the description and as illustrated by way of drawings which accompany the description.
8. A method of manufacturing an improved the roller chain assembly as described in the description and as illustrated by way of drawings which accompany the description.
Description:
ROLLER CHAIN BUSHING TECHNICAL FIELD.

This invention is concerned with the field of power transmission technology. This invention particularly concerned with roller chain bushing.

DESCRIPTION OF THE RELATED ART Roller chains are commonly and extensively used in the power transmissions and conveyor fields. Conventional roller chains includes spaced sets of links interconnected by pins, wherein each of the pins support a substantially cylindrical bushing.

At the outset of the description which follows it is to be understood that ensuing description is only illustrate a particular form of this invention. However, such particular form is only an exemplary embodiment, and without intending to imply any limitation on the scope of this invention.

Accordingly, the description is to be understood as an exemplary embodiment and reading of the invention and not intended to be taken restrictively.

Roller chains may or may not include a roller over the bushing. Roller chains provide a roller mounted upon each of the bushings for engagement with the teeth of a chain sprocket.

Roller chains without a roller are called"rollerless"or "bushed"chains. Rollerless or bushed chains allow the bushing to engage the teeth of a chain sprocket directly, without the buffer of a roller, thereby applying a greater amount of stress and wear to the bushing as compared to the roller chain.

Bushings are commonly termed from a rectangular metal blank having substantially parallel ends and substantially parallel lateral sides substantially perpendicular to the ends of the blank. Rolling of the blank in a direction transverse to its length and substantially parallel to the ends results in substantial engagement of the lateral sides of the blank to define a seam extending the length of the bushing. The blank seam is substantially perpendicular to the ends of the bushing and substantially parallel to the longitudinal axis of the bushing. Such conventionally formed bushings have a number of disadvantages due to the presence of the bushing seam. For instance, the seam permits wear and elongation of the chain over extended periods of use. Further, the presence of the seam may cause vibration in the bushing, which may lead to the cracking of the bushing. The vibration imposed upon the chain by the bushing seam may also produce fatigue failures in the chain and its component as well as excessive noise. Although not mandatory, the presence of conventional bushing seams also encourages bushing seam orientation when assembling the roller chain.

It would be desirable to provide a bushing for roller chains which is rolled into its final configuration such that the bushing seam is of a helical configuration to provide improved joint wear and bushing endurance, reduced socket wear, smoother chain and socket engagement, reduced vibration and noise levels, and a reduced need for seam orientation during assembly.

It would be desirable to provide a bushing for roller chains wherein the bushing seam is of a helical configuration thereby producing a seam joint located at variable radial portions of the bushing to significantly reduce bushing stress

occurring adjacent the seam.

Yet, it would also be desirable to provide a bushing for roller chains having a helical seam wherein formation of the improved bushing may use substantially the same equipment and forming techniques as used in the production of bushing seams having a linear configuration perpendicularly intersecting the seam ends and substantially parallel to the longitudinal axis of the bushing.

We have surveyed the US PTO database and European patent databases and came across many patent applications relating to Transmission chain Technology. The various patent applications filed in US and European Patent office are listed below.

SL. NO PATENT NO DESCRIPTION 1) 5, 376,055 Transmission chain with readily engageable connecting pin.

2) 6,190, 278 Double strand roller chain with phased or Offset pins.

3) 4, 494, 945 Roller chain link construction and method Of Manufacture.

4) 4,515, 031 Chain driven reverse gear for manual Transmission.

5) 3,941, 199 Power Transmission for vehicle.

6) EPO 713 027A1 Free Wheel for a bicycle.

7) W098/08005 Tension Jack with automatic taking up of slack for chain or belt with reversible Motion.

8) EPO 068 886 A3 Drive transmission for roller conveyors

9) EPO 107 060 A3 Chain driven reverse gear for a Transmission.

10) EPO 279 763 A3 Rear wheel suspension mechanism for motorcycle and the like vehicles 11) EPO 307 732 A3 Transmission 12) EPO 372 854 Al Improvements in and relating to roller conveyor systems.

13) WO 91/01228 Variable drive transmission.

The above-cited patents are thoroughly examined as to the content and relevance to our invention. It has been found that three patent specifications are related to our technical field. The following is the critical examination as to technical contents and how our invention is different from the aforesaid patent specifications.

A Critical assessment of the prior art patent specification with reference to our invention is as follows Whereas the unique aspect of relates to US Patent Specification no 5,376, 055 relates to An elongated Transmission chain is formed by roller assemblies and the pairs of link plates extending in parallel spaced relationship outwardly of the roller assemblies to provide a pivotal connection there between. The master link pivotably connects the ends of the elongated chain and includes the pair of link plates overlapping the side plates of the roller assemblies at the ends of the chains.

These master link plates have a pair of space

apertures therein which chains are c-axially aligned with the apertures in the adjacent rollers of the roller assemblies at the ends of the chains.

A pair of threaded fasteners seen in these apertures and extend between the master link plates and through the side plates and rollers. The fasteners are threadably engaged in assembly with the master link plates and are of length not greater than the spacing between the outer surfaces of the master link plates so that they do not extend outwardly thereof.

Whereas the unique aspect of relates to US Patent specification no 4,494, 945 relates to A power transmission roller chain link construction comprises a first link pin plates with a pair of spaced apart substantially parallel link pins secured to said plate in a press-fit so that they extend parallel to the plate. The bushing is fitted over each pin and roller link plate press-fitted on the bushing adjacent each of its ends. The roller is rotatably mounted on each bushing between the roller link plates. The link pins, link pin portion and rod portion extending outwardly from each link pin portion beyond the second link plate, the second link plate being press fitted to the link pin adjacent the opposite ends from the first link plate. The rod portion of each link pin has a threaded area adjacent the second link plate and a nut is threadably engageable on the threaded area.

The link is manufactured by first press fitting the link pins to the first link plate thereafter assembling the bushing with the roller link plates at each end over the pin and assembling a bushing between the plates. Thereafter a second link plate inserted over rod like extensions of the link pins and press fitted to the link pins in the same manner as the first link pin plates. Second link pin plate is tightened against the bushing assembly by a nut, which is threaded on the threaded portion of the rod like extension. A nut, threaded downwardly on a threaded portion of the rod like extension which is adjacent to the second link plate so as to force the plate into position spaced by the same amount from the roller link plate as the first pin link plate. Preferably resilient 0-' Rings are interpose between the associated roller link plates and the pin link plates. After securing the second link plate in position below the threading the nut along the threaded area of the roller portion, the rod portion is broken away from the remaining part of the assembly. Advantageously the resilient 0-Rings is also fitted into groove formed on the associated link pins exteriorly of the second link plates.

Whereas the unique aspect of relates to US Patent specification no 6,190, 278 relates to A power transmission roller chain includes pin links having pins spaced by one pitch and connected to each other plates and the bushing links having

bushing spaced apart from each other and rigidly connected to each other by plates. Two successive pin links are connected each other by a bushing link having the bushing rotate mounted on the pins.

At least one pin link includes a central plate provided with pins alternately protruding from opposite faces of the plate offset from each other by a fraction a pitch, our invention relates to entirely new configuration of bushing rendering to prolonged life and removal of Stress in the chain.

It is to be noted that the prior art description gives in detail information of the technology, method, process and system known in the art. It explains the deficiency in the related art and the object of the invention being to overcome or surmount the problem associated with the prior art. This forms the essential feature and the object of the invention.

SUMMARY OF THE INVENTION In the practice of invention, an improved roller chain assembly provides a plurality of first and second sets of side links interconnected by pins, and a substantially cylindrical bushing circumscribing each pin. The improvement includes the bushing having a longitudinal axis and a pair of opposite ends each lying in a plane wherein said longitudinal axis is substantially perpendicular to the planes. The bushing provides a seam line that intersect the ends and is obliquely related to the planes of the ends to form a substantially helical configuration.

The bushing is formed of a metal blank having a substantially parallelogram configuration. The metal blank includes substantially parallel opposite ends and lateral sides wherein the lateral sides are substantially parallel to each other and obliquely intersect the ends of the blank. The parallelogram blank is rolled into a substantially cylindrical configuration in the direction of the length of the blank ends The substantially engaging lateral sides define a bushing longitudinal seam, which is helically related to the longitudinal axis of the bushing.

Accordingly it is the primary object of the invention to invent a roller chain assembly which reduces or entirely remove the stress in the chain.

It is the another object of the invention to invent a novel roller chain assembly having entirely new ! configuration of bushings leading to prolonged life.

BRIEF DESCRIPTION OF THE DRAWINGS Now the invention will be described with reference to drawings which accompany this description. The nature of invention and the manner in which the invention is to be performed is clearly and extensively described.

The aforementioned advantages of the invention will be appreciated from the following description and accompanying drawings wherein : FIG. 1 is an elevated side view of a typical roller chain, partially in section as taken along section 1-1 of FIG. 2; FIG. 2 is atop plan view with respect to Fig. 1 of a typical roller chain partially shown in section along Section 2-2 of FIG. 1 ; FIG. 3 is an elevational sectional view taken through a

link chain pin along Section 3-3 of FIG. 2, showing the bushing of the present invention and the outer links in elevation ; FIG. 4 is a perspective view of a prior art roller chain bushing; FIG. 5 is a perspective view of a roller chain bushing of the present invention FIG. 6 is a plan view of a sheet metal blank used to form the roller chain bushing of the present invention shown in FIG. 5 ; FIG. 7 is a graph illustrating the radial layout of the helical seam of a roller chain bushing in accord with the Present invention FIG. 8 is a graph illustrating fatigue locations at a roller chain bushing in a bushing constructed in accord with the prior art structure of FIG. 4; and FIG. 9 is a graph to FIG. 8 illustrating the forces occurring at a roller chain bushing seam constructed in accord with the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT A conventional assembled roller chain using a bushing 18 of the present invention is illustrated in FIG. 1-3 by the reference numeral 10. It should be noted that the bushing 18 is shown herein conjunction with the roller chain 10 simply for explanatory purposes. The bushing 18 may also be used in rollerless or bushed chain (not shown). Roller and rollerless chains have their advantages and disadvantages, depending on the application, but the bushing 10 of the present invention may be used in either application. As seen in Figs. 1-3, the roller chain 10 includes side sets of interconnected side links, one set being identified by the reference numeral 12,

and the other set being identified by reference numeral 14. The sets of side links 12, 14'are interconnected by headed pins 16, and the pins 16 are located within the substantially cylindrical roller chain bushings 18. Rollers 20 circumscribe the bushings 18, and the bushings 18 are located within the link holes 22, as appreciated from FIGS. 2 and 3.

The bushing 18 is formed from a substantially flat, planar blank 21 fabricated from a rigid metallic material, such as a ferrous alloy or low to medium carbon steel, as seen in Fig. 6.

The blank 21 has a substantially parallelogram configuration defined by a pair of opposite and substantially parallel ends 24 and a pair of opposite and substantially parallel, lateral sides 26. The lateral sides 26 meet with the ends 24 of the blank 21 at an oblique angle 23, such as 12 degrees. The present invention is not limited to the oblique angle 23 being a 12-degree angle, but rather the inventor is simply familiar with the 12-degree angle due to the inventor's developmental work on the present invention. The blank 21 is rolled in a direction transverse to its length and substantially parallel to a pair of planes established by the ends 24 of the blank 21.

The lateral sides 26 are rolled adjacent one another in substantial engagement to form a seam 30 along the bushing 18.

The seam 30 takes the shape of a helix sthstantially paralle to a longitudinal axis 25 of bushing 18.

With reference to FIG. 4, a prior art bushing is illustrated having lateral sides substantially perpendicular to the ends 24 of the bushing 17 so that the seam 28 perpendicularly intersects the ends of 24 of the bushing 17 and is substantially parallel to the longitudinal axis 25 of the bushing 17.

The roller chain bushing 18 formed in accord with the

present invention, as shown in FIG. 5 provides the seam 30 with a helical configuration by using the oblique angle 23 of the lateral sides 26, as formed by the relationships shown in FIG. 7. FIG. 7, a circle 32 is divided into a plurality of equality spaced radii 34, and the intersection of the radii 34 with the circle 32 is linearly projected to the right, as indicated by lines 36. The lines 36 intersect the equally spaced lines 38 representing equal axis distances on the bushing 18, and the helix 40 representing seam 30 passes through the intersection of the projections 36 with the lines 38.

The helical orientation of the seam 30 reduces the wear at the seam 30, as compared with the linear type of seam 28 shown in FIG. 4, and reduces the elongation of the roller chain 10 due to wear, as compared to when the bushings 28 of the type in FIG. 4 are used. Sprocket wear is also reduced when the bushing 18 of the present invention is utilized on rollerless chains because a smoother chain \ sprocket engagement is produced, thereby reducing the vibration experienced in the drive system.

The helical bushing seam 30 provides improved bushing retention to the inside chain bar, and the reduction in vibration also reduces the chain drive system noise level. Further, helical bushing seam 30 reduces the need for orientating the bushing seam 30 with respect to the pins 16 as is often desired when utilizing the prior art bushings 17 of FIG. 4.

Fatigue resistance of the bushing 18 is also improved as illustrated in the graphs of FIGS. 8 and 9. FIG. 8 represents the prior art forces and fatigue values at 42 adjacent the seam 28, and it will be appreciated that these fatigue forces are not uniform as the resistance to fatigue varies and is non-uniform in a circumferential direction. Conversely, as represented in

FIG. 9, the fatigue forces as represented by line 44 of the bushing 18 utilizing the helical seam 30 provides maximum resistance to fatigue in a circumferential direction adjacent the seam 30, and a uniform resistance to fatigue in a circumferential direction adjacent the seam 30, and a uniform resistance to fatigue is produced in the circumferential direction of the bushing 18.

It is appreciated that the helical configuration of the bushing seam 30 provides unobvious advantages over the prior art bushing seam 28 orientation as shown in FIG. 4, and various modifications to the inventive concepts maybe apparent to those skilled in the art without departing from the spirit and scope of the invention.

It will be understood that the foregoing description is only illustrative of the present invention and is not intended that the present invention is limited thereto. Many other specific embodiment of the present invention will be apparent to one skilled in the art from the foregoing disclosure. Any substitution, alteration or modification of the present invention which come within the scope of claims are. to which the present invention is readily susceptible without departing from the spirit of invention.

The scope of the invention should therefore be determined not with reference to the above description but should be determined, with reference to the appended claims along with full scope of equivalents to which such claims are entitled.