WO2006030448A1

WO2006030448A1 - Offset plate transmission chain

Info

Publication number: WO2006030448A1
Application number: PCT/IN2004/000291
Authority: WO
Inventors: Srinivas Krishna; Senthil Kumar Singaravelu
Original assignee: Tube Investments Of India Ltd.
Priority date: 2004-09-15
Filing date: 2004-09-15
Publication date: 2006-03-23

Abstract

An offset plate transmission chain of lower pitch for the purpose of meeting higher purpose requirements comprising a bush (2) and a pin (3) connecting two offset plates (4). The outer surface of the bush end (5) is juxtaposed with the inner surface of the pin (6). A hole (7) is provided to intercept the said outer surface of the bush end (5) and the said inner surface- of the pin end (6). The said hole (7) overlaps the swept radii (Ra, Rb) of the juxtaposed surfaces (5, 6).

Description

OFFSET PLATE TRANSMISSION CHAIN

FIELD OF INVENTION

This invention relates to offset plate transmission chains of lower pitch to meet high performance requirements.

BACKGROUND OF THE INVENTION

Offset plate transmission chains have been manufactured for several decades. The advantages of the offset plate chain include the fact that they have well distributed wear on each of the pin-bush interfaces. It is also possible to have odd number of links in a closed chain and when run in the proper direction the wearing that takes place is highly reduced. These ultimately increase the chain life and efficiency of the chain.

Despite these inherent advantages, it has not been possible to design offset plate chains to meet chain standards for transmission chains in the lower pitch categories, because the offset becomes extremely sharp, substantially thinning down the area which is offset, during manufacture, resulting in weak offset plate as compared to plates of conventional chains. Offset plate chains of lower pitch are currently not used in motorcycles due to the reasons detailed above.

SUMMARY OF THE INVENTION

The present invention disclose a novel offset plate transmission chain of lower pitch which will allow manufacture of offset plate chains to meet higher performance requirements. The invention proposes to introduce an additional hole between the pitch holes of the plate. This hole is shaped and positioned in such a way so as to reduce the stress concentration on the plate, thereby improving the overall strength. The hole has an added advantage of effectively channeling the flow of relative wind into areas where frictional heat is generated in the chain by the relative movement of chain components when the chain is moving forward, bushed-end first.

Accordingly the present invention provides an offset plate transmission chain comprising a bush and a pin connecting two offset plates, the outer surface of the bush end juxtaposed with the inner surface of the pin and characterized in that a hole is provided to intercept the said outer surface of the bush end and the said inner surface of the pin end, said hole is constructed to overlap the swept radii (R_a) and (R_b) of the juxtaposed surfaces.

BRIEF DESCRIPTION OF DRAWINGS

Fig. 1 shows an isometric view of the offset chain link according to the invention.

Fig. 2 shows a plate of the offset chain link illustrating the outer surface of the bush end.

Fig. 3 shows a plate of the offset chain link illustrating the inner surface of the pin end.

Fig. 4a shows the top view of the plate.

Fig 4b shows the side view of the plate

Fig. 5 shows the wear comparison graph of the conventional chain and the offset chain according to the invention.

Fig. 6 shows the isometric view of the offset chain link with a free running roller. DETAILED DESCRIPTION OF THE INVENTION

Referring to figure 1, the offset chain link (1) comprises a bush (2) and a pin (3) that connects the two offset plates (4) as shown herein. The outer surface of the bushed end (5) is juxtaposed with the inner surface of the pin end (6) when the individual links are interlinked to form a chain. The hole (7) according to the embodiment of the invention, intercepts the said outer surface of the bush end (5) and the inner surface of the pin end (6), thereby cutting part of the link forming the surfaces. The said hole (7) overlaps the swept radii (R_a) and (R_b) of the overlapping surfaces (5) and (6) respectively as shown in figure 1, thereby nesting the offset plates of adjacent links of the chain. In a preferred embodiment a free running roller is provided around the bush to reduce friction. The figure 6 shows this preferred embodiment in which part of the roller only is shown. The roller (8) reduces the friction produced by the movement of the chain (2) and thereby increases the life of the chain.

As it can be seen from figure 2, the hole (7) overlaps the swept radius R_a of the surface (5). Similarly, figure 3 illustrates plate (4) with the inner surface of the pin end (6). The hole (7) is seen to overlap the swept radius R_b of the surface (6).

From figure 4a and 4b it is clear that the thinning down of the offset is reduced thereby increasing the strength of the offset plates.

The advantage of the present invention is that the offset plate transmission chain has an increased wear life and is cost effective as compared to a transmission chain of conventional design. It permits use of the offset design in lower pitch chains by reducing the stress concentration by about 25%.

The table 1 shown below should be read in tandem with figure 5, which illustrates the wear comparison between a conventional chain having a chain length of 1354.63 mm before preloading and a length o 1356.4 mm after preloading the nominal length of the chain is 1358.9 mm and the chain under size is 2.5 mm and the chain in accordance with the present invention having a plate thickness increased from 1.58 to 2.00 mm, with a stress relief hole and a cranking edge radius of 0.5R. The table 1 below quite clearly shows a considerable improvement in the rate of wear in the offset chain of the present invention as compared with the conventional chains. TABLE 1 :

Another significant advantage of the present invention is that it considerably reduces the use of lubricants on the links due to the cooling effect of the relative wind. When the chain is in motion, bush end first, the hole (7) effectively channels the flow of the relative wind into areas which generate frictional heat during motion. Thus the lubrication retention is high and the offset chain proves to be cost efficient.

The offset chain according to the present invention finds its application in motorcycles due to the advantages mentioned above.

Claims

CLAIMS:

1. An offset plate transmission chain link comprising a bush (2) and a pin (3) connecting two offset plates (4), the outer surface of the bush end (5) juxtaposed with the inner surface of the pin (6) characterized by a hole (7) intercepting the said outer surface of the bush end (5) and the said inner surface of the pin end (6), said hole (7) overlapping the swept radii (R_a , R_b) of the juxtaposed surfaces (5, 6).

2. An offset plate transmission chain link as claimed in claim 1, wherein the said bush (2) has a roller installed around it to reduce the friction produced during the motion of the chain.