Bicycle chain

Abstract

The bicycle chain according to the invention is composed of a string of articulated links formed by pairs of outer links (1), stiffened by bolts (2) and pairs of inner links (3) that move freely on bolts (2) spaced apart from each other through rollers (4) having the pitch (distance between holes) Pe=P-2c and Pi=P-2a+2c or Pe=Pi+2s and Pi=P-2a-2s, with the embossed holes of the inner cylindrical links on the outside and on the inside with a portion of the same radius and a portion of length (M1) with an surface with the radius generator =r, having chamfered links at the ends on the surfaces (10, 11, 12, 13) with the angle α=arctangH / E, and the minimum clearance ( a) between the axis of symmetry of the bolt and the axis of symmetry of the embossed holes of the inner links is a≥N 1 *(sinα) / 2.

Description

[0001] Bicycle chain

[0002] The invention relates to a transmission chain used in bicycles with both single-speed and multi-speed configurations.

[0003] Known inventions such as U20180017131A and US4265134A feature chains with drilled bolts and various deformations and chamfers in the links. In these cited inventions, the bushings are replaced with embossing areas in the inner links. The drawings in these inventions show the embossed hole in the inner link with uniform wall thickness (Fig. 6). However, in reality, the thickness varies along section M (Fig. 5), being thicker at the base and thinner at the tip due to the embossing effect. The tapered exterior of the embossed hole in the inner link along section M creates a wedging effect (Fig. 14) when theroller exerts force on it, causing friction between the links.

[0004] The chain links are constructed with a hole distance equal to P (chain pitch). After assembly, due to the play between the symmetry axis of the embossed hole in the inner link and the symmetry axis of the bolt, as well as the tension in the chain during operation, the pitch becomes P, P+2a, P, P+2a, and the sum of two consecutive pitches will be S=2P+2a (Fig. 4).

[0005] In multi-speed bicycles, the chain is not always parallel to the plane of rotation of the chain wheels (Fig. 11). Due to the chain deviation when entering and exiting the chain wheels, the outer link will exert force on the inner link, creating friction.

[0006] Advantages of the invention:

[0007] 1. Eliminates the wedging effect between the roller and the embossed hole of the inner link.

[0008] 2. Partially eliminates the frictional force between the links (resulting from chain deviation).

[0009] 3. Adjusts the chain pitch so that the sum of two consecutive pitches equals 2P.

[0010] 4. Reduces friction between the embossed holes of the inner link and the bolts.

[0011] An example of the invention in connection with Fig. 1-19:

[0012] Fig. 1: Assembly drawing of the bicycle chain.

[0013] Fig. 2: Drawing of the outer link. Fig. 3: Drawing of the inner link.

[0014] An example of the invention in connection with Fig. 1-19:

[0015] Fig. 1: Assembly drawing of the bicycle chain.

[0016] Fig. 2: Drawing of the outer link.

[0017] Fig. 3: Drawing of the inner link.

[0018] Fig. 4: Explanatory drawing of chain elongation during operation.

[0019] Fig. 5: Drawing showing the real shape of the stamped inner link.

[0020] Fig. 6: Drawing showing the shape of the stamped hole in the inner link according to cited inventions.

[0021] Fig. 7: Drawing of the inner link stamping according to the invention.

[0022] Fig . 8 : The drawing of the chain-sprocket assembly

[0023] Fig. 9: Explanatory drawing of the pitch modification of inner and outer links according to the invention.

[0024] Fig. 10: Drawing showing dimensions a, b, and c, where (c) is shown with its maximum possible value.

[0025] Fig. 11: Sketch of the chain engagement with chain wheels in multi-speed bicycles.

[0026] Fig. 12: Drawing highlighting the calculation of angle a.

[0027] Fig. 13: Drawing of the roller and modified inner link assembly according to the invention.

[0028] Fig. 14: Drawing of the forces acting due to the taper of the embossed link.

[0029] Fig. 15: Drawing of tension T when the bolt acts on the chain (when it is deviated).

[0030] Fig. 16: Schematic drawing of forces due to tension T in the chain.

[0031] Fig. 17: Drawing showing the dependence of play size on the maximum deviation angle a. Fig. 18: Sketch showing the action of the two components of tension T when the bolt contacts only one inner link.

[0032] Fig. 19: Drawing highlighting the compensator (s).

[0033] The bicycle chain according to the invention is composed of a string of articulated links formed by pairs of outer links (1), stiffened by bolts (2) and pairs of inner links (3) that move freely on bolts (2) spaced apart from each other through rollers (4).

[0034] The execution of the two embossed holes of the inner flange is made by embossing plus cutting, resulting in an almost conical shape (due to the effect of embossing) on the outside of the embossing on the M portion (Fig 5). Due to the existence of this conicity during the operation of the chain, the force acting on the roller ( Fl) will act on the taper where it breaks down, and one of the components (F2) acts on the inner links (Fig 14) which will press the outer links with the same force (F2) (F2<F1) producing friction during the relative movement of the two links. The elimination of this shortcoming is done by changing the geometric shape of the embossing of the inner links portion Ml which is an surface (14) with the radius generators ( Fig 3 ), Due to this modification, the contact surface between the inside of the roll and the outside of the embossing will be a straight line (Fig.l ).

[0035] On bicycles with multiple speeds, the direction of movement of the chain (on the free portion where it does not act with the chain wheels) is not always parallel to the plane of rotation of the chain wheels with which it acts (Fig 11). The maximum deviation angle is achieved when the chain it acts with the first or last sprocket of the sprocket box (Fig 11) and is ai and a2. The size of the pressing forces that act during the chain deflection depends on the size of the deflection angle a and the tension T in the chain.In order to reduce the forces acting during chain deflection, the links will be chamfered at the ends with an angle a (Fig 2, Fig3). By making these chamfers, the chainrings can rotate laterally, reducing friction.

[0036] Since the lengths E, V, K (Fig. 11) are approximately equal and considering the existing play between the links, we can assume a=ai=a2. The maximum angle a=arctg H / E (Fig. 11). The value of angle a varies between a=0 and a=arctg H / E. Considering the side play of the chain and the correct operation of the chain, the chamfer of the links will start 0.5 mm from the center of the link holes towards their ends (Fig. 2, Fig. 3) Bicycle chains have a chain pitch (generally 12.7) for both inner and outer links, (the pitch being the distance between the axe of symmetry of the links holes). Through the action of the tension in the chain during operation, and due to the play between the axis of symmetry of the hole of the inner eclipse and the axis of symmetry of the bolt, the chain will have the sum of two consecutive steps of the form S=P+a+P+a=2P+ 2a (fig. 4).

[0037] To bring the chain to the form in which the sum of two consecutive steps is 2P, the step of the inner links must be reduced by 2a ( Pi=P-2a ) and then the sum of two consecutive steps will be S=P+a+( P-2a )+a=2P.

[0038] However, this modification does not completely reduce the chain play on the sprocket wheel (due to the existence of the play between the center of symmetry of the roller and the center of symmetry of the embossed hole of the inner links equal to b (Fig.lO). To completely eliminate the play, insert a compensation rate 2c that will be subtracted from the step of the outer links and added to the step of the inner links ( Fig.lO ) Pe=P-2c,Pi=p- 2a+2c. The evidence of this compensator can be seen in (Fig.9) where the chain acts with a rack that has the shape of the teeth specific to the bicycle chain and where the value of the sum of two consecutive steps will be S=P-2c+a+P+2c+a=2P

[0039] The maximum value of (c) ( Fig.lO ) is Cmax=a+b where: a- is the play between the symmetry axis of the bolt and the symmetry axis of the embossed hole in the inner link, a=(Di-Db) / 2, b- is the play between the symmetry axis of the ebossed hole and the symmetry axis of the roller,

[0040] Di -is the inner diameter of the embossed hole,

[0041] Db- is the bolt diameter, b=(Dir-De) / 2, where:

[0042] Dir- is the inner diameter of the roller,

[0043] De- is the outer diameter of the embossing. The value of (c) cannot exceed cmax, otherwise, the chain will not fit on the chain wheels (Fig. 9). 0<c<a+b The value of (c) will be chosen based on operating conditions (mud, dust). By this stiffening of the chain by the chain wheels, the chain play on the chain on the chain wheels is partially or totally eliminated, making the permissible elongation of the chain until the change to be greater (elongation can only be accumulated in two steps, not in several steps).

[0044] To stiffen the chain with the sprockets, another 2s compensator can be used, which is added to the pitch of the outer links and subtracted from the inner links (Fig. 19). The shape of the steps will be:

[0045] Pi=P-2a-2s

[0046] Pe=P+2s, Where the sum of two consecutive steps is 2P ( Fig.19) and the value of (s) is 0<s<b.

[0047] During the operation of the chain at the entrance and exit from the chain wheels that are not in the same plane as the chain, it will deviate by an angle a. If clearance (a) allows the bolt to act in a single point (Rl=0, R=T, Fig.15, Fig. 16, Fig.18) the reaction force is minimal R=T and T=T1+T2.

[0048] If clearance (a) does not allow contact in a single point, the reaction force is Rmax=T+Rl (Fig.l5,Fig.l6).

[0049] The clearance value (a) is given from the right triangle (Fig.17) where N1 is the hypotenuse (the distance between the points of contact of the bolt with the inner eclipses) and (2a) the side of the triangle opposite the angle a. From the right triangle it follows that 2a / Nl=sina so a=Nl *(sina) / 2.

[0050] In order to reduce the friction, we must have the minimum play ( a ) a>Nl *(sina) / 2.

[0051] With ordinary chains, if I increase the play (a), I increase the initial elongation of the chain, so it is not practiced. Increasing the play of the chains according to the invention does not bring any change in operation (the sum of two consecutive steps is the same 2P)

[0052] The value of the elements marked with letters will have values depending on the type of chain (the pitch of the chain and the number of speeds of the bicycle where it works).

[0053] Advantages of using the invention:

[0054] 1. Reduction of frictional forces in the chain.

[0055] 2. Reduction of initial elongation of the chain.

[0056] 3. Eliminating the initial play of the chain on the sprocket.

[0057] 4. Increasing the transmission efficiency

Claims

Claims1.The bicycle chain according to the invention is composed of a string of articulated links formed by pairs of outer links (1), stiffened by bolts (2) and pairs of inner links (3) that move freely on bolts (2) spaced apart from each other through rollers (4), characterized in that thexhain pitch is in the form Pe = P - 2c and Pi = P - 2a + 2c where (P) is the chain pitch, (Pe) is the pitch of the outer links, (Pi) is the pitch of the inner links, (c) is acompensator with values 0 < c < a + b, where (b) is the clearance between the symmetry axa of the roller (4) and the symmetry axa of the embossed hole of the links inner (3), and (a) is the clearance between the symmetry axis of the pin and thesymmetry axis of the embossed hole of the inner links (3).2 The bicycle chain according to the invention is composed of a string of articulated links formed by pairs of outer links (1), stiffened by bolts (2) and pairs of inner links (3) that move freely on bolts (2) spaced apart from each other through rollers (4), characterized in that the: chain pitch is in the form Pe = P + 2s and Pi = P - 2a - 2s where (P) is the chain pitch, (Pe) is the pitch of the outer links, (Pi) is the pitch of the inner links, (s) is acompensator with values 0 < s < b, where (b) is the clearance between the symmetryaxes of the roller (4) and the symmetry axis of the embossed hole of the inner links (3), and (a) is the clearance between the symmetry axis of the pin and the symmetry axis of the embossed hole of the inner links(3).3 The bicycle chain according to claims 1 and 2, characterized in that the : outer links are chamfered at both ends on surfaces (10) and (11) starting from 0.5 mm from the center of the two holes towards the ends of the side, on the side that comes into contact with the inner links, at an angle a = arctan H / E, where (H) is half the thickness of the sprocket boxand (E is the distance between the axis of symmetry a of the chain wheel cassette and the axis of symmetry of the chain drive wheel.4 The bicycle chain according to claims 1 and 2, characterized in that the: inner links are chamfered at both ends on surfaces (12) and (13) starting from 0.5 mm from the center of the two holes towards the ends of the side, on the side that comes into contact with the outer links, at an angle a = arctan H / E, where (H) is half the thickness of the sprocket boxand(E) is the distance between the axis of symmetry a of the chain wheel cassette and the axis of symmetry of the chain drive wheel.

5. The bicycle chain according to claims 1 and 2, characterized in that the: the embossing shape of the holes of the inner links (3) will be of the same diameter on the outside and on the inside it will have a cylindrical portion and at the extremity on one portion (Ml) it has a surface (14) with a generator with radius=r.

6. The bicycle chain according to claims 1 and 2, characterized in that the: the size of the game (a) between the axis of symmetry of the bolt and the axis of symmetry of the embossed hole of the innen links (3) has a value minimum of a = Nl*(sin a) / 2, where a is the maximumthe chain deviation angle, and N1 is the distance between the contact points between the pin and the holes of the inner links.

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