WO2021086166A1

WO2021086166A1 - Sprocket for use with roller chain

Info

Publication number: WO2021086166A1
Application number: PCT/MY2020/000017
Authority: WO
Inventors: Thian Chai LEE
Original assignee: Excel South Asia Sdn. Bhd.
Priority date: 2019-10-30
Filing date: 2020-10-21
Publication date: 2021-05-06

Abstract

The present invention relates to a sprocket for the use with roller chain (10) formed by a plurality of teeth (70) that meshes with rollers of a roller chain. In particular, the present invention relates to sprocket for the use with roller chain (10) to transmit mechanical energy in automobile engines, in particular, motorcycles.

Description

SPROCKET FOR USE WITH ROLLER CHAIN

1. TECHNICAL FIELD OF THE INVENTION

The present invention relates to a sprocket for the use with roller chain formed by a plurality of teeth that meshes with rollers of a roller chain. In particular, the present invention relates to sprocket for the use with roller chain to transmit mechanical energy in automobile engines, in particular, motorcycles.

2. BACKGROUND OF THE INVENTION

As is well known, sprockets and roller chain are indispensable elements in power transmission wherein power transmission in chain drive is generally achieved by meshing a roller chain with sprockets. Sprockets are rotating parts with teeth that are used in conjunction with a roller chain in transmitting mechanical energy and torque and are widely used as power transmission means in various motors and internal combustion engines such as motorcycles, bicycles, or belt conveyors or industrial machines.

A sprocket is typically laid out using the dimensions of the roller chain which is to run upon it, specifically the pitch, roller diameter, and the roller width of the chain. In other words, sprockets must be compatible to a roller chain in order for them to work effectively and collaboratively. That means, they must both have the same thickness and pitch. The sizes of roller chain commonly used are categorized, standardized and maintained by International Standards such as International Organization for Standardization (ISO) and American National Standards Institute (ANSI). Thus, sprockets manufacturers tend to produce sprockets to interact with either International Organization for Standardization (ISO) or (American National Standards Institute) ANSI roller chain, depending upon the manufacturer's primary marketplace.

It has been reported that, when the standard roller chains are used in motorcycles in which high loads are encountered, the roller chains do not exhibit good gears changing experience wherein the change between the gears is large and the choice of secondary ratio is limited. Therefore, there is a rising demand for increasing choices of gear ratio by reducing the size of the roller chain. In order to reduce the size of the chain, it must be achieved by reducing the chain pitch by means such as thinning all the components of the chain, which further lead to a total weight reduction. However, there arises a problem that the strength of the roller chain is impaired if the pitch is reduced, which may not be realistic. Among the existing standard roller chains, it is commonly understood that the strength of the chain decreases as the size decreases. Hence, a roller chain having a size that deviates from the conventional International Standards while maintaining its strength is demanded. Similarly, sprockets must also be produced compatibly with the size of the deviated roller chain. However, all the sprockets in the existing market are adhered to ISO or ANSI dimensions to mate with the standardized roller chains.

Hence, it entails a necessity to have a sprocket which is compatible to a roller chain that deviates from the conventional International Standards. 3. SUMMARY OF THE INVENTION

Accordingly, it is the primary aim of the present invention to provide a sprocket for use with a roller chain that deviates from conventional dimensions.

It is yet another objective of the present invention to provide a sprocket for use with a roller chain wherein the strength of the sprocket is maintained while deviating from conventional dimensions.

It is yet another objective of the present invention to provide a sprocket for use with a roller chain wherein the transmission efficiency is improved while deviating from conventional dimensions. It is yet another objective of the present invention to provide a sprocket for use with a roller chain that has a reduced thickness and reduced weight. It is yet another objective of the present invention to provide a sprocket for use with a roller chain that has a different pitch than the International Standards.

It is yet another objective of the present invention to provide a sprocket for use with a roller chain that has unique teeth profile.

It is yet another objective of the present invention to provide a sprocket for use with a roller chain that does not wear easily.

Additional objects of the invention will become apparent with an understanding of the following detailed description of the invention or upon employment of the invention in actual practice.

According to the preferred embodiment of the present invention the following is provided:

A sprocket for use with at least a roller chain, comprising: at least a substantially disk-shaped body portion having a substantially circular profile; at least a through hole is formed at the centre of said body portion for insertion of at least a driven shaft; plurality of teeth comprised of plurality of spaced-apart tooth is formed around the outer periphery of said body portion for meshing with rollers of a roller chain; characterized in that said sprocket has a pitch within the range of 14.25mm to 14.31mm.

4. BRIEF DESCRIPTION OF THE DRAWINGS

Other aspect of the present invention and their advantages will be discerned after studying the Detailed Description in conjunction with the accompanying drawings in which: FIG. 1-A illustrate the exemplary front view of a sprocket for use with a roller chain according to the preferred embodiment of the present invention.

FIG. 1-B and 1-C illustrate the exemplary front and perspective views of a sprocket for use with a roller chain according to another embodiment of the present invention.

FIG. 2-A and 2-B illustrate the exemplary perspective front and back views of the sprocket for use with a roller chain according to another embodiment of the present invention.

FIG. 3-A and 3-B illustrate the exemplary perspective views of a sprocket for use with a roller chain according to another embodiment of the present invention. FIG. 4 and 5 illustrate the exemplary enlarged views of the teeth of the sprocket for use with a roller chain according to the present invention.

FIG. 4 illustrates an exemplary top view of the roller chain according to present invention. FIG. 6 illustrates the front view of the sprocket for use with a roller chain according to the present invention showing the principal dimensions of the sprocket.

FIG. 7 illustrate a table showing the sizes of the sprocket for use with a roller chain according to the present invention. FIG.8-A and 8-B illustrate the exemplary side views of the sprocket for use with a roller chain according to the present invention.

5. DETAILED DESCRIPTION OF THE DRAWINGS

In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, it will be understood by the person having ordinary skill in the art that the invention may be practised without these specific details. In other instances, well known methods, procedures and/or components have not been described in detail so as not to obscure the invention. The invention will be more clearly understood from the following description of the embodiments thereof, given by way of example only with reference to the accompanying drawings, which are not drawn to scale. As used in this disclosure and the appended claims herein, the singular forms "a", "an", and "the" include plural referents unless the context clearly dictates or denotes otherwise.

Throughout the disclosure and claims of this specification, the word "comprise" and variations of the word, such as "comprising" and "comprises," means "including but not limited to," and is not intended to exclude, for example, other components, integers or steps. "Exemplary" means "an example of" and is not intended to convey an indication of a preferred or ideal embodiment, "such as" is not used in a restrictive sense, but for explanatory purposes.

Referring to FIG. 1-A, the exemplary front view of a sprocket for the use with a roller chain (10) according to the preferred embodiment is shown. Said sprocket (10) comprising at least a substantially disk-shaped body portion (30) having a substantially circular profile and at least a through hole (50) is formed at the centre of said body portion (30) for insertion of at least a driven shaft (not shown in the drawings). While said through hole (50) is shown as a substantially circular or rounded profile, said through hole (50) may further comprise at least an indented surface (51) formed around its circumference or at least a protruded surface (53) formed around its circumference, or their combination thereof, thereby forming ridges or teeth to match, compatible or mesh with grooves in a mating driven shaft as illustrated in FIG 1-B and 1-C. This type of through hole (50) having the indented surfaces (51) and protruded surfaces (53) in known as the spline holes (50). Said sprocket (10) further comprising plurality of teeth (70) comprised of plurality of spaced-apart tooth (71) is formed around the outer periphery or the circumference of said body portion (30) for meshing with rollers of a roller chain. Each tooth (71) comprising at least a first and second convex walls (73a, 73b) curving from the outer periphery of said body portion (30), at least a first and second concave walls (75a, 75b) curving respectively from said first and second convex walls (73a, 73b), and at least a substantially flattened surface (77) connecting said first and second concave walls (75a, 75b) defining the tip of each tooth (71), thereby defining a gap or recess (79) between neighbouring teeth (70) for engagement with roller of a roller chain. The first and second concave walls (75a, 75b) of each tooth (71) of said sprocket (10) are formed from a radius of curvature of 13.5mm and with a tolerance of ± 0.4mm.

Optionally, as illustrated in FIG. 2-A and 2-B, said sprocket (10) may further comprise at least a hub (90) provided on at least one side of said body portion (30) of said sprocket (10) and attached into the through hole (50) of the sprocket (10). Said hub (90) comprising at least a through hole (91) formed at the centre of said hub (90) for insertion of at least a driven shaft (not shown in the drawings) wherein said through hole (91) of said hub (90) comprising at least an indented surface (93) formed around its circumference or at least a protruded surface (95) formed around its circumference, or their combination thereof, thereby forming ridges or teeth to match, compatible or mesh with grooves in a mating driven shaft. This type of through hole (91) having the indented surfaces (93) and protruded surfaces (95) in known as the spline holes (91). Alternatively, the hub (90), as one part of the sprocket (10), is a detachable hub which is detachably attached into the through hole (50) of said body portion (30). Otherwise, the through hole (91) of the hub (90) shares the same rotational axis with the through hole (50) of the sprocket (10) wherein both through hole (50, 91) are compatible with each other for insertion of the same driven shaft. In other words, the through hole (91) of said hub (90) is located substantially parallel and compatible to the through hole (50) of said sprocket (10) for the insertion of the same driven shaft into both through holes (50, 91). Optionally, the sprocket (10) is not limited to the design or shape as described above. The sprocket (10) may further include additional components such as mudgrooves to held shed mud and grit, or lightening holes (110) for sprocket's weight reduction, or any other additional components as the sprocket (10) deems fit and suitable, or any of the combination thereof, upon purchasers' request. As an example, the lightening holes (110) can be provided on the sprocket (10) with or without hub as shown in FIG. 3-A and 3-B.

The dimensions of the sprocket (10), which are also the characteristic features of the present invention will be explained below in reference to the Figure 4 to Figure 8. As is well known, sprockets (10) and roller chain are indispensable elements in power transmission wherein power transmission in chain drive is generally achieved by meshing a roller chain with sprockets (10). In order for them to work effectively and collaboratively, they must be compatible to each other, which means they must both have the same pitch. The sprocket (10) according to the present invention has a sprocket pitch of 14.2875mm, preferably within the range of 14.25mm to 14.31mm, matching and mating with an associated roller chain having the chain pitch of 14.2875mm, preferably within the range of 14.25mm to 14.31mm. The term "sprocket pitch" used herein refers to the distance between the centre points of the neighbouring recesses (79) of the teeth (70) whereby this distance is designated by letter P in FIG. 4. Besides, the roller diameter of a roller chain is also important in constructing and laying out the sprocket teeth (70) whereby the distance between neighbouring teeth must be able to accommodate or fit the rollers of a roller chain. Therefore, the distance of the neighbouring teeth (70) of sprocket (10) is always greater than the roller diameter of a roller chain. In the present invention, the space between the neighbouring teeth (70) has a distance greater than 8.51mm, to match and mate with a roller chain having roller diameter of 8.51mm, preferably within the range of 8.43mm to 8.51mm, wherein this space or distance is indicated by letter S in FIG. 5.

The sprocket pitch (P) or chain pitch (P) and the roller diameter of a roller chain are the determining or essential factor in calculating the principal dimensions of the sprocket (10). The principal dimensions of the sprocket (10), particularly the outside diameter, pitch circle diameter, bottom diameter and caliper diameter of the sprocket (10) are of particular importance in determining the size of the sprocket (10), which is shown in FIG. 6. Outside diameter refers to the diameter over the tips of the teeth (70), wherein it is indicated by Do. In other words, it is the diameter of the sprocket (10) including teeth (70). Pitch diameter is the diameter of the theoretical circle that passes through the centers of the link pins when a roller chain is wrapped around or meshed with the sprocket (10) wherein it is indicated by Dp. Bottom diameter, indicated by DB refers to the distance across the sprocket from the bottom of opposite tooth recesses (79). In the illustration of the present invention, as the bottom of the each recess (79) is formed from the first convex wall (73a) of one tooth (71) curving from the outer periphery of the body portion (30) and connected by the second convex wall (73b) of another tooth (71) curving from the same outer periphery of the body portion (30), the bottom diameter can also refer to the diameter of said body portion (30). If the sprocket (10) has an odd number of teeth there will be no exact opposite recess (79), so caliper diameter is used. Caliper diameter as indicated by Dc, is the same as the bottom diameter (DB) for a sprocket (10) with an even number of teeth (70). For a sprocket (10) with an odd number of teeth (70), it is the distance from the bottom of one tooth recess (79) to the bottom of the nearest opposite tooth recess (79).

FIG. 7 lays out a table of the principal dimensions of the sprocket (10) calculated using a given number of teeth (70), sprocket pitch (P), 14.2875mm or the chain pitch and roller diameter of a roller chain. 8.51mm and it can be seen that, generally, the greater the number of teeth (70), the larger the sprocket (10) is. Outside diameter (Do) of the sprocket (10) can be obtained by the calculation formula below:

.

Pitch diameter (DP) the sprocket (10) can be obtained by the calculation formula below: CKET PITCH

180

TEETH NO)

Bottom diameter (DB) the sprocket (10) can be obtained by the calculation formula below:

D_B = D_P — ROLLER DIAMETER

Caliper diameter (Dq the sprocket (10) can be obtained by the calculation formula below:

It can be deduced from the table and these formulas that the number of teeth (70) for a specific pitch (P) and roller diameter will determine the sprocket (10) size. Also, the sprocket (10) according to the present invention has a minimum of 8 teeth and up to a maximum of 70 teeth depending on purchasers' requirement, while maintaining the sprocket pitch (P) and roller diameter of a roller chain. However, the number of teeth (70) for the specified pitch (P) and roller diameter will determine the tooth profile, wherein different number of teeth (P) results in different tooth profile. It is contemplated that the design and shape, in particular the shape of the tooth can be varied, can be changed for different circumstances or different purchasers' request, wherein each tooth (71) may be blunt, may be curved, may be sharp, or any combination thereof.

FIG. 8-A and 8-B show the side views of the sprocket (10) with and without the hub (90). The sprocket (10) has a thickness of 4.9mm, preferably the thickness is within the range of 4.5mm to 5.1mm, whereby said thickness is indicated by letter T and this thickness (T) is maintained throughout 8 teeth to 70 teeth. Although the thickness (T) is maintained regardless of the number of teeth (70), it is contemplated that the thickness (T) can be varied and subject to changes, depending on purchasers' request.

While the present invention has been shown and described herein in what are considered to be the preferred embodiments thereof, illustrating the results and advantages over the prior art obtained through the present invention, the invention is not limited to those specific embodiments. Thus, the forms of the invention shown and described herein are to be taken as illustrative only and other embodiments may be selected without departing from the scope of the present invention, as set forth in the claims appended hereto. The scope of the invention encompasses numerous alternatives, modifications and the equivalents. Of necessity, there are many alternative ways of configuring and implementing the invention to suit particular installations and environments while providing biological outcomes of differing design.

Claims

WHAT IS CLAIMED IS:

1. A sprocket for use with at least a roller chain (10), comprising: at least a substantially disk-shaped body portion (30) having a substantially circular profile; at least a through hole (50) is formed at the centre of said body portion (30) for insertion of at least a driven shaft; plurality of teeth (71) comprised of plurality of spaced-apart tooth (70) is formed around the outer periphery of said body portion (30) for meshing with rollers of a roller chain; characterized in that said sprocket (10) mates with a roller chain having a chain pitch (P) within the range of 14.25mm to 14.31mm.

2. The sprocket for use with a roller chain (10) as claimed in Claim 1, wherein said sprocket (10) further comprising at least a hub (90) provided on at least one side of said body portion (30) of said sprocket (10), wherein said hub (90) shares the same through hole

(50) of said sprocket (10).

3. The sprocket for use with a roller chain (10) as claimed in Claim 1, wherein the thickness (T) of said sprocket (10) is within the range of

4.4mm to 5.1mm.

4. The sprocket for use with a roller chain (10) as claimed in Claim 1 or 2 wherein each tooth (71) comprising at least a first and second convex walls (73a, 73b) curving from the outer periphery of said body portion (30); at least a first and second concave walls (75a, 75b) curving respectively from said first and second convex walls (73a,

73b); at least a substantially flattened surface (77) connecting said first and second concave walls (75a, 75b).

5. The sprocket for use with a roller chain (10) as claimed in Claim 3 wherein said first and second concave walls (75a, 75b) of each tooth (71) are formed from a radius of curvature of 13.5mm with a tolerance of ±.0.4mm.

6. The sprocket for use with a roller chain (10) as claimed in any one of the preceding claims, wherein said sprocket (10) has a minimum of 8 teeth and maximum of 70 teeth.