Title of Invention

AN IMPROVED POWER TRANSMISSION CHAIN

Abstract

An improved power transmission chain comprising plurality of block assemblies each said block assembly being connected with a pair of outer plates to the next block assembly to form the transmission chain, each said block assembly consists of a pair of bushes located between a pair of inner plates, a pair of pins passing through the respective bush from the pair of bushes and fixed to the said pair of outer plates connecting successive block assemblies, and a freely rotating roller around each bush wherein the outer diameter of the bush is 1.2 to 1.3 times the inner diameter of the bush and the length of the bush is 2.15 to 2.35 times the inner diameter of the bush.

Full Text

The invention relates to a power transmission chain having improved performance suitable for applications such as transmission chain used in two wheeler vehicles. The transmission chain according to the invention comprises plurality of block assemblies consisting of bush-pin bearings having modified geometry resulting in a reduction of contact pressure and change in the chain pitch during engagement with sprockets providing many fold increase in performance. Automotive power transmission chains are used in two wheelers for specifically transmitting power to the rear wheel. These chains are subjected to shock loading and abrasive wear during operation at high speed due to higher load and abrasive wear, rapid elongation of the chain takes place. In motorcycle application the rapid elongation due to high load, speed and abrasive atmosphere causes the chain to mis-engage sprocket and M during running. Thus there exists a need for improving the Use of the chain to ensure noise fine performance and smooth engagement with sprocket. To improve performace of chains, it is a common practice teat the bearing members namely the pins and knishes used in chains are coated with anti-wear high hardness coatings like nit riding, hardchrome plating and composite self lubricating electro less nickel. Several chain manufactures have developed high performance variety having improved chain Fume by increasing the bush height and the plate thickness. These methods of improving the performance of the chains, involve additional treatments and more material resulting in increasing the processing cost and raw material cost. A transmission chain with ccM\siderably lower elongation compared to a conventional transmission chain made in accordance with existing ISO or JIS standards is obtained by making certain specific dimensional changes. Surprisingly it was find that by keeping the ratio of the outer diameter to inner diameter of the bushes in the range of 1.2 to 1.3 and the ratio of the length of the bushes to the inner diameter of the bushes in the range of 2.15 to 2.35, the performance of the transmission chain has substantially improved. Percentage elongation with time in a transmission chain with bushes having the abovementioned limitation was considerably less compared to the percentage of elongation in a similar conventional transmission chain. Thus the invention provides a power transmission chain comprising plurality of block assembles each said block assembly being connected with a pair of outer plates to the next block assembly to form the transmission chain, each said block assembly consists of a pair of bushes located between a pair of inner plates, a pair of pins passing through the respective bush from the pair of bushes and fixed to the said pair of outer plates connecting successive block assemblies, and a freely rotating roller around each bush characterised in that the outer diameter of the bush is 1.2 to 1.3 times the inner diameter of the bush and the length of the bush is 2.15 to 2.35 times the inner diameter of the bush. The invention will be described in detail with reference to the accompanying drawings. Figures 1 and 2 shows the top view and side view respectively of the transmission chain according to the invention. Figures shows sectional view along the line A-A in figure 2. Figure 4 shows the inside portion of a conventional bush and that of the bush used in the transmission chain according to the invention. Figure 5 is a graph showing the elongation versus operating time of both the conventional transmission chain and the transmission chain according to the invention. The power transmission chain according to the invention comprises plurality of block assemblies. Each block assembly is connected with the next block assembly by means of a pair of outer plates (2). Each said block assembly consists of a pair of bushes (4) located between a pair of inner plates (1). A pair of pins (5) passing through the respective bushes food the pair of bushes (4) and fixed to the pair of outer plates (2) connecting succussive block assemblies. The bushes and pins are made keeping outer diameter (Do) of the bushes 1.2 to 1.3 times the inner diameter (Dj) of the bushes and keeping the length (L) of the bushes 2.15 to 2.35 times the inner diameter (Di) of the bushes. Most preferred ratio of outer diameter (Do) to the inner diameter (Di) of the bushes is 1.25 and the most preferred ratio of the length (L) to the inner diameter (Di) of the bushes is 2.25. It was found that providing serration (S) in the inside portion of the bushes improve the performance of the transmission chain due to more effective lubrication by the lubricant flow through the serration. The elongation measurements in conventional power transmission chains and power transmission chains according to the invention having similar sizes were conducted for different working periods for comparison. Figure 5 shows the variation observed in relative percentage of elongation with time in respect of conventional power transmission chain and transmission chain according to the invention. It clearly shows that the percentage of elongation with time is considerably reduced in respect of the transmission chain according to the invention. Power transmission chain according to the invention are excellent for using with two wheelers such as modem motorcycles. They provide better performance and are cost effective. WE CLAIM: 1. An improved power transmission chain comprising plurality of block assemblies each said block assembly being connected with a pair of outer plates (2) to the next block assembly to form the transmission chain each said block assembly consists of a pair of bushes (4) located between a pair of inner plates (1), a pair of pins (5) passing through the respective bush from the pair of bushes (4) and fixed to the said pair of outer plates (2) connecting successive block assemblies, and a freely rotating roller (3) around each bush (4) wherein the outer diameter (Do) of the bush (4) is 1.2 to 1.3 times the inner diameter (Dj) of the bush (4) and the length (L) of the bush (4) is 2.15 to 2.35 times the inner diameter (Dj) of the bush (4). 2. The power transmission chain as claimed in claim 1, wherein the outer diameter (Do) of the bush (4) is 1.25 times the inner diameter (Dj) of the bush (4) and the length (L) of the bush (4) is 2.25 times the irmer diameter (Dj) of the bush (4). 3. The power transmission chain as claimed in claims 1 or 2, wherein the inner surface of the bush (4) is provided with serrations (S).

Documents:

0450-mas-2001 abstract-duplicate.pdf

0450-mas-2001 abstract.jpg

0450-mas-2001 abstract.pdf

0450-mas-2001 claims-duplicate.pdf

0450-mas-2001 claims.pdf

0450-mas-2001 correspondence-others.pdf

0450-mas-2001 correspondence-po.pdf

0450-mas-2001 description (complete)-duplicate.pdf

0450-mas-2001 description (complete).pdf

0450-mas-2001 drawings-duplicate.pdf

0450-mas-2001 drawings.pdf

0450-mas-2001 form-1.pdf

0450-mas-2001 form-18.pdf

0450-mas-2001 form-26.pdf

0450-mas-2001 form-3.pdf