阅读说明：本技术 动力传动链 (Power transmission chain ) 是由 M·福勒 于 2018-07-10 设计创作，主要内容包括：一种与具有多个齿(6)的驱动构件(4)一起使用的动力传动链(2),其中：(i)所述动力传动链(2)包括多个链节(8),这些链节通过连接构件(9)和枢轴装置(10)枢转地连接在一起,使得所述动力传动链(2)在使用中能够绕过所述驱动构件(4)；(ii)所述枢轴装置(10)中的每一个都包括从所述链节(8)的相对侧(16、18)朝向彼此延伸的第一枢轴和第二枢轴(12、14)；(iii)所述第一枢轴和第二枢轴(12、14)具有彼此面对并且间隔开的相邻端部(20、22)；(iv)所述动力传动链(2)包括多个接合构造(24),使得能够与所述驱动构件(4)接合；(v)所述接合构造(24)位于所述第一枢轴和第二枢轴(12、14)的所述相邻端部(20、22)之间；并且所述接合构造(24)以及所述第一枢轴和第二枢轴(12、14)的所述相邻端部(20、22)的间隔使得使用中的所述动力传动链(2)总是定位在所述驱动构件(4)上,以实现所述驱动构件(4)和所述动力传动链(2)之间的驱动传递的最大效率,而与所述驱动构件(4)的直径无关。(A power transmission chain (2) for use with a drive member (4) having a plurality of teeth (6), wherein: (i) the power transmission chain (2) comprising a plurality of links (8) pivotally connected together by connecting members (9) and pivot means (10) such that the power transmission chain (2) can pass around the drive member (4) in use; (ii) each of said pivot means (10) comprising first and second pivots (12, 14) extending from opposite sides (16, 18) of said link (8) towards each other; (iii) the first and second pivots (12, 14) having adjacent ends (20, 22) facing and spaced apart from each other; (iv) the power transmission chain (2) comprises a plurality of engagement formations (24) enabling engagement with the drive member (4); (v) the engagement formation (24) being located between the adjacent ends (20, 22) of the first and second pivots (12, 14); and the spacing of the engagement formations (24) and the adjacent ends (20, 22) of the first and second pivots (12, 14) is such that the power transmission chain (2) in use is always positioned on the drive member (4) to achieve maximum efficiency of drive transfer between the drive member (4) and the power transmission chain (2) irrespective of the diameter of the drive member (4).)

1. A power transmission chain for use with a drive member having a plurality of teeth, wherein:

(i) the power transmission chain comprising a plurality of links pivotally connected together by connecting members and pivot means such that the power transmission chain can pass around the drive member in use;

(ii) each of the pivot means comprises first and second pivots extending from opposite sides of the link towards each other;

(iii) the first and second pivots having adjacent ends facing and spaced apart from each other;

(iv) the power transmission chain comprises a plurality of engagement formations enabling engagement with the drive member;

(v) the engagement formation is located between the adjacent ends of the first and second pivots; and is

(vi) The engagement formation and the spacing of the adjacent ends of the first and second pivots is such that the power transmission chain in use is always positioned on the drive member to achieve maximum efficiency of drive transfer between the drive member and the power transmission chain irrespective of the diameter of the drive member.

2. The power transmission chain of claim 1, wherein each of the engagement formations is a receiving formation, and wherein the receiving formation is for receiving one of the teeth on the drive member.

3. The power transmission chain of claim 2, wherein the receiving formation has end walls that define opposite ends of the receiving formation and that position the first and second pivots along a circular path.

4. The power transmission chain of claim 3, wherein the end walls extend parallel to each other and transverse to the power transmission chain, and wherein the end walls are curved such that curves extend toward each other, thereby defining a waisted shape.

5. The power transmission chain of claim 4, wherein the end wall is formed of a cylinder.

6. The power transmission chain of claim 5, wherein the cylinder is rotatable relative to the first and second pivots.

7. The power transmission chain of claim 5, wherein the cylinder is fixed relative to the first and second pivots.

8. The power transmission chain of any of claims 1-3, wherein the end walls are parallel to each other and extend transverse to the power transmission chain, and wherein the end walls are flat, thereby defining a straight-sided shape.

9. The power transmission chain of claim 1, wherein each of the engagement formations is a tooth formation, and wherein the tooth formations are for receipt in receiving recesses formed between adjacent teeth on the drive member.

10. The power transmission chain of any preceding claim, wherein each link includes a first side plate member and a second side plate member, and wherein the first and second side plate members are spaced apart.

11. The power transmission chain of any of the preceding claims, wherein each chain link has an end portion comprising a contact portion and a restraining portion, wherein the restraining portion extends towards the contact portion, wherein in use the contact portions of the chain links are in contact with each other, and wherein in use the restraining portion restrains movement of the power transmission chain such that the power transmission chain does not collapse.

12. The power transmission chain of claim 11, wherein the limiting portion is flat, wherein the contacting portion is flat, wherein the limiting portion is at a first angle of inclination, wherein the contacting portion is at a second angle of inclination, and wherein the second angle of inclination is greater than the first angle of inclination.

13. The power transmission chain of claim 12, wherein each of the first and second side plate members has at least one of the limiting portions and at least one of the contact portions.

14. The power transmission chain of any preceding claim, wherein each link has one of the engagement formations on an inner surface of the power transmission chain for engaging the drive member when, in use, it is located on the inner side of the power transmission chain.

15. The power transmission chain of any of claims 1-13, wherein each link has one of the engagement formations on an outer surface of the power transmission chain for engaging the drive member when, in use, the drive member is located on the outer side of the power transmission chain.

16. The power transmission chain of any of claims 1-13, wherein each link has one of the engagement formations on an inner surface of the power transmission chain for engaging the drive member when, in use, the drive member is located on the inside of the power transmission chain, and wherein each link has one of the engagement formations on an outer surface of the power transmission chain for engaging the drive member when, in use, the drive member is located on the outside of the power transmission chain.

17. The power transmission chain of any of the preceding claims, wherein the connecting member is a link plate member.

18. The power transmission chain and drive member combination according to any one of the preceding claims.

19. Apparatus provided with a power transmission chain according to any one of claims 1-17 or a combination according to claim 18.

20. Apparatus according to claim 19 in the form of a bicycle, tricycle, motorcycle, chainsaw, windmill or engine.

Disclosure of Invention

The present invention relates to a power transmission chain, and more particularly, to a power transmission chain for use with a drive member having a plurality of teeth.

Power transmission chains for use with drive members having a plurality of teeth are well known.

A first known power transmission chain is a roller chain. The roller chain has a plurality of engagement formations enabling engagement with the drive member. The engagement formations are in the form of receiving formations for receiving the teeth of the drive member. One example of the use of a roller chain is a bicycle. The roller chain of the bicycle passes around a front drive member in the form of a crank drive member and also passes around a rear drive member in the form of a gear. The known roller chain can also be used in many other different types of equipment, including for example tricycles, motorcycles and chain saws.

A second known power transmission chain is a silent chain. The silent chain also has a plurality of engagement configurations enabling engagement with the drive member. The engagement formation is in the form of a tooth formation for receipt in a receiving recess formed between adjacent teeth on the drive member. Silent chains are used in high torque applications requiring high efficiency and large amounts of power transmission.

A typical such application is the use of a silent chain as a timing chain for an engine. Silent chains are also commonly referred to as HY-VO chains.

Power transmission chains are known for effecting power transmission between various drive members. The drive member may be a drive member that drives the power transmission chain in the case of a front sprocket drive member on a bicycle, or the drive member may be a drive member that is driven by the power transmission chain in the case of a rear gear drive member on a bicycle. Known power transmission chains are formed from links pivotally connected together by pivots that extend completely laterally through the links.

Known power transmission chains do not transmit drive as efficiently as desired. More specifically, known power transmission chains always bypass two spaced apart drive members, such as a front drive member in the form of a bicycle crank and a rear drive member in the form of a bicycle gear. The two drive members always have different diameters. The different diameters mean that the two drive members will have a different number of teeth. The engagement configuration and teeth are not always in optimal engagement for different diameters and different numbers of teeth. As a result, the known power transmission chain does not work efficiently for both drive members.

The object of the present invention is to reduce the above-mentioned problems.

Accordingly, in one non-limiting embodiment of the present invention, there is provided a power transmission chain for use with a drive member having a plurality of teeth, and wherein:

(i) the power transmission chain comprising a plurality of links pivotally connected together by connecting members and pivot means such that the power transmission chain can pass around the drive member in use;

(ii) each of the pivot means comprises first and second pivots extending from opposite sides of the link towards each other;

(iii) the first and second pivots having adjacent ends facing and spaced apart from each other;

(iv) the power transmission chain comprises a plurality of engagement formations enabling engagement with the drive member;

(v) the engagement formation is located between the adjacent ends of the first and second pivots; and is

(vi) The engagement formation and the spacing of the adjacent ends of the first and second pivots is such that the power transmission chain in use is always positioned on the drive member to achieve maximum efficiency of drive transfer between the drive member and the power transmission chain irrespective of the diameter of the drive member.

The power transmission chain of the present invention can provide the following advantages as compared with known power transmission chains.

(a) The efficiency of drive transmission between the drive member and the power transmission chain is improved. This is particularly true for roller chains. The power transmission chain of the present invention may also require less lubrication than known power transmission chains. This is particularly true for silent chains.

(b) Wear of the power transmission chain and/or the drive member is reduced. This reduction in wear is due to the power transmission chain being correctly positioned on the teeth of the drive member. This reduction in wear may in turn lead to the advantage of being able to use thinner components and/or lighter materials and/or cheaper materials than would otherwise be the case.

(c) Eliminating the chordal action, also known as the polygon effect. The chordal action is that the power transmission chain and the drive member travel at different speeds because they are of different sizes and therefore have different numbers of teeth. The elimination of the chordal action can be achieved with a low number of teeth in the drive member.

(d) The noise of the chain in use is reduced.

(e) Thinner and/or lighter and/or cheaper materials are used for producing the power transmission chain and/or the drive member, since the driving force between the drive member and the power transmission chain is well distributed between all teeth on the drive member that are in contact with the power transmission chain during use.

(f) As the power transmission chain is positioned on the drive member in use, the teeth of the drive member and the components of the power transmission chain may be reduced in size. This reduction in size can then result in savings in manufacturing materials.

In a first embodiment of the invention, the power transmission chain is one in which each of the engagement formations is a receiving formation and in which the receiving formation is for receiving one of the teeth on the drive member. Such power transmission chains may be referred to as roller chains and may be used for bicycles, tricycles, motorcycles and chain saws.

The receiving formation may have end walls defining opposite ends of the receiving formation and such that the first and second pivots are located along a circular path.

The power transmission chain may be one in which the end walls extend parallel to each other and transversely to the power transmission chain, and in which the end walls are curved such that the curves extend towards each other, thereby defining a waisted shape. The end wall may be curved by being formed from a cylinder. Alternatively, the cylinder may be an elliptical member or other shaped member. The end walls (e.g. cylinders) may be rotatable relative to the first and second pivots, or alternatively they may be fixed relative to the first and second pivots. To reduce friction between the teeth and the end walls, the open chain system may employ a rotational arrangement. The fixed structure arrangement may be used for a closed system enabling lubrication and thus the lubricant minimizes friction between the teeth and the end wall.

Alternatively, the power transmission chain may be one in which the end walls are parallel to each other and extend transversely to the power transmission chain, and in which the end walls are flat, thereby defining a straight-sided shape.

In a second embodiment of the invention, the power transmission chain may be one in which each of the engagement formations is a tooth formation and in which the tooth formation is for receipt in a receiving recess formed between adjacent teeth on the drive member. Such a power transmission chain may be referred to as a silent chain or an HY-VO chain, and may be used as a timing chain.

In all embodiments of the present invention, the power transmission chain may be one in which each link includes a first side plate member and a second side plate member, and in which the first and second side plate members are spaced apart.

In all embodiments of the invention, the power transmission chain may be one in which each link has an end portion comprising a contact portion and a restricting portion, wherein the restricting portion extends towards the contact portion, wherein in use the contact portions of the links contact each other, and wherein in use the restricting portion restricts movement of the power transmission chain such that the power transmission chain does not collapse. May collapse inwardly and/or outwardly depending on the configuration and intended use of the power transmission chain. The contact portion may be inside the power transmission chain. Alternatively, the contact portion may be outside the power transmission chain. The power transmission chain may be one in which the connecting members are extended, and if this occurs, the contact portions may not contact each other as required to prevent possible collapse of the power transmission chain. Providing the contact portion outside the power transmission chain may allow the contact portion (e.g., the contact plate) to be made of a different material than other portions of the power transmission chain. More specifically, the contact portion may be made of a flexible material that is less robust than the rest of the power transmission chain. The final configuration may help the contacting portions properly engage each other during the life of the power transmission chain. Proper operation of the contact portions can effectively control the path in which each tooth on the drive member enters its engaged configuration (e.g. it engages the receiving recess). This control can effectively reduce noise and/or vibration. This in turn allows the chain and the drive member to be of the same size and, importantly, to be made much smaller than comparable known prior art chain and sprocket arrangements.

The power transmission chain may be one in which the restricting portion is flat, in which the contacting portion is flat, in which the restricting portion is at a first inclination, in which the contacting portion is at a second inclination, and in which the second inclination is greater than the first inclination.

The power transmission chain may be one in which each of the first side plate member and the second side plate member has at least one of the restricting portions and at least one of the contact portions.

In all embodiments of the invention, the power transmission chain may be one in which each link has one of the engagement formations on an inner surface of the power transmission chain for engaging the drive member when, in use, the drive member is located inside the power transmission chain. Such a power transmission chain may be used, for example, in a bicycle, tricycle or motorcycle, wherein the transmission is such that the drive member is always located inside the power transmission chain in use. Such power transmission chains can be used for some complex gear systems, for example on bicycles and tricycles.

Alternatively, the power transmission chain may be one in which each link has one of the engagement formations on an outer surface of the power transmission chain for engaging the drive member when, in use, it is located outside the power transmission chain.

Alternatively, the power transmission chain may be one in which each link has one of the engagement formations on an inner surface of the power transmission chain for engaging on the drive member when located inside the power transmission chain in use, and in which each link has one of the engagement formations on an outer surface of the power transmission chain for engaging the drive member when located outside the power transmission chain in use. Such power transmission chains can be used for some complex gear systems, for example on bicycles and tricycles.

Where the power transmission chain is one in which each link has one of the engaging formations on only an inner surface of the power transmission chain or only an outer surface of the power transmission chain, there will typically be only one of the restricting portions and one of the contacting portions for each of the links for that surface. Where the power transmission chain is one in which each link has one of the engaging formations on an inner surface of the power transmission chain and one of the engaging formations on an outer surface of the power transmission chain, there will typically be one of the restraining portions and one of the contact portions on the inner surface of the power transmission chain and one of the restraining portions and one of the contact portions on the outer surface of the power transmission chain.

In all embodiments of the invention, the connecting member may be a connecting plate member.

The invention also extends to a combination of a power transmission chain and a drive member of the invention.

The invention also extends to an apparatus when equipped with a power transmission chain of the invention or a combination of a power transmission chain of the invention and a drive member. The apparatus may be in the form of, for example, a bicycle, a tricycle, a motorcycle, a chainsaw, a windmill or an engine. The device may be other types of devices that require the use of a power transmission chain.

Drawings

Embodiments of the invention will now be described, by way of example only, and with reference to the accompanying drawings, in which:

FIG. 1 illustrates a portion of a first power transmission chain of the present invention in the form of a roller chain and used on a drive member;

FIG. 2 is an enlarged view of a portion of FIG. 1 from a different angle;

FIG. 3 is a view from below and to one side of a portion of the first power transmission chain shown in FIG. 1;

FIG. 4 is a view from above and to one side of the portion of the power transmission chain shown in FIG. 3;

FIG. 5 is a view from below and one side showing more of the power transmission chain shown in FIG. 3;

FIG. 6 is a view from above and to one side of a chain link forming part of the first power transmission chain shown in FIG. 1;

FIG. 7 is a view from below and to one side of the portion of the first power transmission chain of the present invention shown in FIG. 1, and showing one of the links in an enlarged view;

FIG. 8 is a view from above and to one side of the portion of the power transmission chain illustrated in FIG. 7, and showing one of the links in an enlarged view;

FIG. 9 is a view from above and to one side of the alternative link shown in FIGS. 7 and 8;

FIG. 10 is an enlarged view of a portion of the link shown in FIG. 9;

FIG. 11 is an enlarged view from above and to one side of another alternative link shown in FIGS. 7 and 8 and which can be used in a second power transmission chain of the present invention;

FIG. 12 is an exploded view of a portion of the first power transmission chain shown in FIG. 1;

FIG. 13 is a side elevational view of a first drive member for use with the power transmission chain of the present invention;

FIG. 14 is a side elevational view of a second drive member for use with the power transmission chain of the present invention;

FIG. 15 is a side elevational view in simplified form of a derailleur gear system that utilizes the power transmission chain of the present invention;

FIG. 16 illustrates a known roller chain on the front crank drive member and the rear gear drive member of the bicycle;

FIG. 17 illustrates the roller chains of the present invention on the front crank drive member and the rear gear drive member of the bicycle;

FIG. 18 illustrates the operation of a known power transmission chain around a drive member and shows how the tips of the teeth are positioned at different locations in the power transmission chain, resulting in a loss of transmission efficiency;

FIG. 19(a) shows how a known power transmission chain having 16, 24 and 32 teeth loses transmission efficiency due to the chain pivot center being in a different position;

FIG. 19(b) is for comparison with FIG. 19(a) and shows how the power transmission chain of the present invention can be used with a drive member having 16, 24 and 32 teeth, and the power transmission chain pivot center remains constant at all times, providing maximum transmission efficiency;

FIG. 20 is a view showing a portion of FIG. 1 and showing how the pivot axis of the power transmission chain is positioned on the circumference of the drive member;

FIG. 21 is a view similar to FIG. 20, but showing how the pivot of the power transmission chain can be modified to appear outside the circumference of the drive member;

FIG. 22 is a view similar to FIG. 20, but showing how the pivot axis of the power transmission chain can be modified to appear within the circumference of the drive member;

FIG. 23 illustrates a portion of a third power transmission chain of the present invention in the form of a silent chain and used on the drive member;

FIG. 24 is an exploded view of a portion of a fourth power transmission chain of the present invention having a contact portion on the outside of the power transmission chain, rather than on the inside of the power transmission chain as shown in FIG. 2;

FIG. 25 shows a portion of a fifth power transmission chain of the present invention, the power transmission chain having additional members shown in a first position; and

FIG. 26 shows a portion of the fifth power transmission chain shown in FIG. 25, but with the additional member in a second position.

Detailed Description

Referring to fig. 1-22, a power transmission chain 2 for use with a drive member 4 having a plurality of teeth 6 is shown. The power transmission chain 2 is called a roller chain, and it can be used for, for example, bicycles, tricycles, motorcycles, chain saws, and windmills.

The power transmission chain 2 comprises a plurality of chain links 8 pivotally connected together by connecting members 9 and pivot means 10 such that the power transmission chain 2 can bypass the drive member 4 in use. Each of the pivot assemblies 10 includes a first pivot 12 and a second pivot 14. The first pivot 12 and the second pivot 14 extend towards each other from opposite sides 16, 18 of the link 8, respectively. As best shown in fig. 7 and 8, the first and second pivots 12, 14 have adjacent ends 20, 22, respectively, that face and are spaced apart from one another to define a gap.

The power transmission chain 2 comprises a plurality of engagement formations 24 enabling engagement with the drive member 4. The engagement formation 24 is located between the adjacent ends 20, 22 of the first and second pivots 12, 14. The spacing of the engagement formations 24 and the adjacent ends 20, 22 of the first and second pivots 12, 14 is such that the power transmission chain 2 is always positioned on the drive member 4 to achieve maximum efficiency of drive transfer between the drive member 4 and the power transmission chain 2 regardless of the diameter of the drive member 4. The engagement formation 24 is shaped such that the first pivot 12 and the second pivot 14 lie along the path of a circle 26 which can be circumscribed by the tip 28 of the tooth 6 of the drive member 4.

The power transmission chain 2 is one in which each of the engagement formations 24 is a receiving formation 30, and in which the receiving formation 30 is for receiving one of the teeth 6 on the drive member 4.

The receiving formation 30 has end walls 32, 34 which define opposite ends of the receiving formation 30. The end walls 32, 34 position the first pivot 12 and the second pivot 14 along the path of the circle 26. As can be seen from the figures, the end walls 32, 34 extend parallel to each other and transversely to the power transmission chain 2.

In one embodiment of the present invention, as shown in fig. 1-8, the end walls 32, 34 are curved such that the curves extend toward each other, thereby defining a waisted shape.

In another embodiment of the invention as shown in fig. 9 and 10, the end walls 32, 34 are formed of cylinders. The cylinder may be rotated relative to the first pivot 12 and the second pivot 14, for example for an open chain system, which rotation will reduce friction between the end walls 32, 34 and the teeth 6 of the drive member 4. The cylinder may optionally be fixed relative to the first pivot 12 and the second pivot 14, for example in a closed chain system. The closed chain system can have a lubricating action that minimizes friction between the end walls 32, 34 and the teeth 6 of the drive member 4.

In another embodiment of the invention, shown in fig. 11 and 12, the end walls 32, 34 are parallel to each other and extend transversely to the power transmission chain 2, but they are also flat and therefore they define a straight-sided shape.

The power transmission chain 2 may be made of various materials, including metal and plastic materials. In use of the power transmission chain 2, the connecting member 9 can be extended by a very small amount, but still be able to change the initial position of each tooth 6 in its receiving formation 30. If stretching occurs, the first tooth 6 can fit exactly in the first receiving formation 30 as required, but the second tooth will gradually fit less perfectly in its second receiving formation 30 and a misalignment will gradually occur on the third tooth 6 and the subsequent teeth 6. To counteract the effect of the receiving formation 30 changing shape, such as to reduce the optimum performance and efficiency of the power transmission chain 2, it is preferred that the end walls 32, 34 are curved, the curve preferably being formed as part of a cylinder as shown in fig. 9, but optionally curved as shown in fig. 1-8. Other curved shapes may be employed such that end walls 32, 34 may be formed from oval-shaped members.

Fig. 23 shows a third power transmission chain 36, which is called a silent chain or an HY-VO chain. The power transmission chain 36 has an engagement formation 24. However, each engagement formation 24 in the power transmission chain 36 is in the form of a tooth formation 38. The tooth formations 38 are adapted to be received in receiving recesses 40 formed between adjacent teeth 6 on the drive member 4. As can be appreciated from fig. 20, each tooth 6 on the drive member 4 has one side 39 forming part of one receiving recess 40 and an opposite side 41 forming part of the other receiving recess 40.

The power transmission chain 2 and the power transmission chain 36 are also such that each link 8 has an end portion 42 comprising a contact portion 44 and a limiting portion 46. The restricting portion 46 extends inwardly toward the contact portion 44. The contact portions 44 of the links 8 contact each other. The restricting portions 46 restrict the movement of the power transmission chains 2, 36 so that the power transmission chains 2, 36 do not collapse.

The restriction 46 is flat. The contact portion 44 is flat. The restriction portion 46 is at a first inclination angle. The contact portion 44 is at a second angle of inclination. The second angle of inclination is greater than the first angle of inclination.

The power transmission chains 2, 36 are such that each of the links 8 includes a first side plate 48 and a second side plate 50. The first side plate 48 and the second side plate 50 are spaced apart. Each of the first side plate 48 and the second side plate 50 has at least one of the restricting portions 46 and at least one of the contact portions 44.

As can be seen from a comparison of fig. 3 and 4, each link 8 has one of the engagement formations 24 on the inner surface 52 of the power transmission chain 2. Such an inner surface 52 is intended to engage, in use, the teeth 6 on the drive member 4 when the drive member 4 is located inside the power transmission chain 2. Each link 8 also has one of the engagement formations 24 on the outer surface 54 of the power transmission chain 2. The outer surface 54 is for engaging the teeth 6 on the drive member 4 when the drive member 4 is located outside the power transmission chain 2 in use. This particular use of the power transmission chain 2 is illustrated in fig. 15, it being understood that the power transmission chain 2 bypasses the different drive members 4. In an alternative embodiment of the invention using only one drive member 4, the power transmission chain 2 may be one in which each link 8 has only one of the engagement formations 24 on the inner surface 52 of the power transmission chain 2 and is adapted, in use, to engage a tooth 6 on the drive member 4 when the drive member 4 is located inside the power transmission chain 2. Alternatively, the power transmission chain 2 may be one in which each link 8 has only one of the engagement formations 24 on the outer surface 54 of the power transmission chain 2 and is adapted to engage, in use, a tooth 6 on the drive member 4 when the drive member 4 is outside the power transmission chain.

In an alternative embodiment of the invention (not shown), the power transmission chain 2 described above may be replaced by a power transmission chain 36.

As shown in fig. 3, 4 and 12, the link 8 includes a connecting member 56 mounted on the first pivot 12 and the second pivot 14. The connecting member 56 connects the links 8 together so that the links 8 can pivot about the pivot means 10 and thus bypass the drive member 4.

Referring now to fig. 11 and 12, a portion of a power transmission chain 58 similar to power transmission chain 2 is shown. For ease of comparison and understanding, similar components to those in power transmission chain 2 are given the same reference numerals.

The power transmission chain 58 has an accommodation formation 60 of a different shape than the accommodation formation 30 in the power transmission chain 2. As shown, the receiving formation 60 has straight side walls 62.

Fig. 13 shows the drive member 4. Fig. 14 shows a drive member 64, which is an alternative to the drive member 4. It will be seen that the drive member 4 has a tooth 6 with a substantially pointed tip. Instead, the drive member 64 has teeth 66 with squared tips 68.

Fig. 16 shows a known roller chain 69 on the front crank drive member 71 and the rear gear drive member 73 of the bicycle.

FIG. 17 shows the roller chain 75 of the present invention on the front crank drive member 77 and the rear gear drive member 79 of a bicycle.

Fig. 18 illustrates how the power transmission chain 69 used in fig. 16 does not operate as efficiently as desired. More specifically, fig. 18 shows that because the polygons are identical, and the points on the polygons are not in the same location, the known power transmission chain 69 cannot fit precisely as desired on the front crank drive member 77 and the rear gear drive member 79 because they are of different sizes.

Fig. 19(a) shows that in a known power transmission chain having 16 teeth, 24 teeth and 32 teeth, the only distance to remain constant for all numbers of teeth and all diameters of the drive members is the tooth tip separation distance "x". This means that in the known drive chains the pivot centre moves with a smaller and larger number of teeth, so that the known power transmission chains cannot be connected precisely in order to replace the maximum transmission efficiency of different drive members having different diameters.

Fig. 19(b) shows how the power transmission chain of the present invention having 16 teeth, 24 teeth and 32 teeth provides the maximum drive transmission efficiency. This is because the centers of the first pivot 12 and the second pivot 14 remain in the same position regardless of how many teeth the drive member 4 has.

Fig. 20 is an enlarged view of a portion of fig. 1 and shows one of the links 8 with its pivot 10 located on the circumference of the drive member 4.

Fig. 21 is a view similar to fig. 20, but showing a modification of the power transmission chain 2. More specifically, fig. 21 shows a power transmission chain 70, wherein like components to those of the power transmission chain 2 are given the same reference numerals for ease of comparison and understanding. In fig. 21 it will be seen that the link 8 has been modified so that the pivot means 10 has a first pivot 12 and a second pivot 14 which occur outside the circumference of the drive member 4.

Fig. 22 is also similar to fig. 20, but shows another modification to the power transmission chain 2. In fig. 22, a power transmission chain 72 is shown, which is similar to the power transmission chain 2 except that the links 8 have been modified so that the pivot means 10 with their first and second pivots 12, 14 appear inside the periphery of the drive member 4. In fig. 22, similar components to those in the power transmission chain 2 are again given the same reference numerals for convenience of comparison and understanding.

Referring to FIG. 24, a portion of a power transmission chain 74 is shown. For comparison and understanding, like components from the previous drawings are given the same reference numerals. In fig. 24, it can be seen that the contact portion 44 is located outside the power transmission chain 74, rather than inside the power transmission chain 2 as shown in fig. 2. As shown in fig. 24, providing a contact portion on the outside of the power transmission chain 74 may make the chain portion 76 made of a more flexible and less strong material than the rest of the chain portion. This in turn may enable the chain members to stretch and also bring the contact portions 44 into proper contact. The contact portion is thus able to control the path of the drive chain groove into the drive member sprocket. This in turn helps to control the operation of the power transmission chain, particularly to reduce noise and vibration. This in turn may enable the power transmission chain and the drive member to be of the same size and much smaller than is possible with known prior art systems.

Referring to fig. 25 and 26, a portion of the fifth drive chain 76 is shown. For ease of comparison and understanding, similar components have the same reference numerals as in the previous figures. As shown, the drive chain 76 has additional members 78, 80. As shown, the members 78, 80 provide increased contact area with the gear teeth 6. The increased contact area provided by the members 78, 80 enables the pressure to spread, resulting in a reduction in the load on the drive chain 76. This in turn may reduce wear in the drive chain 76. The increased contact area provided by the members 78, 80 increases friction and therefore the drive chain 76 is most suitable for use in a closed system where the drive chain 76 is susceptible to good lubrication. The members 78, 80 may be other shapes as long as they provide an increased contact area.

It will be understood that the embodiments of the invention described above with reference to the drawings are given by way of example only and that modifications are possible. Thus, for example, power transmission chains 2, 36, 70, 72, 74 and 76 may be used with drive members having different numbers of teeth than those described above. The individual components shown in the drawings are not limited to use in their drawings and they may be used in other drawings and in all aspects of the invention. The invention also extends to individual components referred to and/or illustrated above, singly or in any combination.