WO2007147909A1

WO2007147909A1 - Bicycle connecting rod and pedal/bottom bracket bearing assembly

Info

Publication number: WO2007147909A1
Application number: PCT/ES2007/000160
Authority: WO
Inventors: Pablo Carrasco Vergara
Original assignee: Rotor Componentes Tecnológicos, S.L.
Priority date: 2006-06-14
Filing date: 2007-03-22
Publication date: 2007-12-27
Also published as: WO2007147909B1; TW200804130A

Abstract

Pedal/bottom bracket bearing assembly with semi-integrated shaft design, hollow connecting rods and self-aligning housings, the connection between the shaft and the connecting rod that forms it being sliding, and incorporating a double-thread screw that, depending on whether it rotates in one direction or the other, makes it possible to increase or reduce the final distance between the two connecting rods, and therefore it is possible to eliminate play and to adjust the preload on the bearings. The connecting rods are made hollow by means of a drilling operation at the end opposite the pedal, but with a reinforcing ring being maintained at the entry to the hole. Also, the housings, for their part, will provide knuckle-joint accommodation for the bearings by means of respective rings of spherical outer surface.

Description

SET OF BELTS AND PEPALIER FOR BICYCLES

The present invention, mainly applicable to bicycles, affects the cranks, the bottom bracket and the support of these on the bicycle, collecting a series of improvements aimed at the lightness and reliability of these power transmission elements in the bicycle.

STATE OF THE TECHNIQUE

In the world of cycling there is a permanent evolution in terms of the lightness of all components, provided that stiffness and reliability are not affected, logically driven by performance improvement that would allow less effort or greater speed for the cyclist.

Specifically, in relation to connecting rods, there is currently the widespread use of hollow connecting rods, usually of aluminum (US6755095, US6612033, US6508002, US6314834, US6227070, EP1120336, US5988016), and of connecting rods made of fiber composite material carbon, which are usually filled with aluminum and foam inserts (US7013753, US6899402, EP1571075), which although they are more expensive and usually less reliable, of course they can become as light as hollow aluminum cranks, also having a Special claim possibly for being technologies of aerospace origin, or simply for fashion. In any case, it can be said that those of aluminum, the forged and hollow ones, entail a greater technological investment, associated only with the production of very high series, while those of carbon are normally associated with more artisanal works and shorter series, Io which has opened the market to more manufacturers, although of course there are also examples of very high technology that has reached the bicycle industry with carbon fashion, manufacturing quite large series.

As for the bottom bracket, in recent years the use of bearings outside the bottom bracket (US6755095, DE19751879) has been generalized, positioned by means of two cups on both sides of the tube of the bicycle that forms said box. This is justified because it relieves the bearings, which being able to be bigger, they are in themselves less requested, and being more separated they support the flexor moment in the axis much better; and also allows to use shafts of greater diameter, generally very hollow and light, because for a given torsional strength, the larger the diameter, the smaller the section of the necessary shaft (and therefore the weight of the axle).

This construction of the bottom bracket by external bearings is normally combined with the use of thru axles (US6755095, US2005011304), that is, they do not have restrictions on their axial displacement, in this case the connecting rods are those that support the axial fixation of the axle. As they are through axles, they are assembled in their respective bearing supports once they have been installed on the bicycle, which provides a great ease of use at the time of assembly and maintenance.

Since the axis can always enter from one of the sides, they are usually presented with a configuration called "integrated axis", so that the axis is integral with one of the connecting rods, thus forming a single piece "connecting rod-axis" of face to the user. In the market there are axes of this form, integrated, some integral with the connecting rod on the side of the plates and others with the opposite connecting rod.

For all these through axes, the axial fixation of the axis is determined by the distance between connecting rods, which enclose the assembly [bowl] - [bottom bracket] - [bowl]. Since said bottom bracket, which is part of the bicycle, is normally a piece of low precision, in general said axial fixation is an uncertain fixation, which to be solved proceeds in two different ways:

1. Variable connecting rod distance: which is resolved by means of the sliding anchor of the non-integral connecting rod. At its free end, the shaft has a cylindrical drag profile that allows the crank to be displaced by means of a screw that pushes it to achieve the axial positioning of the crank, and it has a slot-shaped opening to allow it to easily enter and then hug the shaft using screws that close that slot (US6755095) materializing the radial fixation while ensuring the axial position.

2. Fixed distance between connecting rods: in this case the non-integral connecting rod has a fixed anchor, tightened by means of a thrust screw against a stop that forms the axis itself or simply a conical anchor. Since the distance between connecting rods cannot be varied, the way to compensate for this uncertainty is through the use of silly rings, rubber washers and wavy washers (which act as a spring).

The first option is the mechanically more logical and efficient solution, but there are connecting rods whose construction prevents that opening, as happens for example with most of the carbon fiber connecting rods. Also the use of screws to make the connecting rod jointly embrace the shaft (closing said groove) is seen in the market as an excess of weight to be considered. Which then leads to the second option. Then, said elastic elements generally serve to absorb the aforementioned axial uncertainty, but sometimes creating a new uncertainty in what refers to the axial force or preload on the bearings, which may be a key factor limiting the life of said bearings

It is worth highlighting an option that today comes to light: the manufacturer Shimano for its top model of mountainbike, the XTR, which in its 2003 version was the precursor of the cranks for mountainbike (which were already being used in general in the cranks of BMX), announces for the 2007 model to dispense with the crank arm embraced with the excuse of eliminating weight, now passing a fixed distance between cranks, but in this case saving the said uncertainty by using a slotted nut with a brake screw, similar to the grooved ring shown in US2006101941 in FIG4.

Finally, it is also possible to talk about the system of cups and bearings that support the connecting rod systems with an integrated shaft. In general, external bearings provide a number of important advantages already mentioned, however the inaccuracies provided by many bottom brackets greatly limit the life of said bearings. That is, to the uncertainty of axial length, the parallelism between the two faces is joined of the tube or bottom bracket, where they will support the cups once tightened, and the uncertainty of alignment of the threads of both sides. Both uncertainties are much worse than the length, since the shaft would be supported by two bearings that are not aligned, thus affecting, not only the useful life of said bearings, but also increasing the friction and efficiency in Ia power transmission.

SUMMARY OF THE INVENTION

Next, a series of improvements are proposed on the elements described above, specifically in the construction of the connecting rods, in their anchoring to the axle, in the type of axle, and in their assembly in the bicycle.

Regarding the connecting rods, a metal connecting rod, preferably of high tensile strength and fatigue aluminum, is proposed, which in order to be light and cheap in its construction, is provided with a hole made in the head of the connecting rod - end of the connecting rod opposite the one that corresponds to the anchoring of the pedal - and which extends along the crank arm so that it defines a hollow connecting rod. In order to withstand the efforts around the entrance to said hole, the connecting rod head will have a protuberance or excess material at its end, so that once said hole is made, said protuberance will form a reinforcement ring - perpendicular to the connecting rod arm - capable of correctly transmitting the tangential stresses that occur when pedaling at the connecting rod head at its interface with the shaft, in addition to the tensile stresses that correspond to the expansive force generated by the shaft embedment in Ia connecting rod.

Since said connecting rod has such a reinforcement ring, it cannot take

The solution for anchoring to the shaft by means of a slot-shaped opening and screws that, when tightened, would allow it to hug the shaft. However, as a sliding anchor for axial axle fixing is considered very convenient, what is proposed here is to abandon the concept of an integrated shaft, integral to one of the connecting rods, to move to the concept of a "semi-integrated" axis: one of The connecting rods will be removable with conventional "butt" or conical tightening anchorage, and the other connecting rod will be a joint part of the shaft, but assembled by sliding anchor in order to allow varying the final distance between connecting rods, thus being able to eliminate gaps in the bottom bracket and regulate the axial preload of the bearings.

Therefore, the shaft will be of asymmetric construction, and at its end intended to couple the sliding connecting rod, a factory assembly of said connecting rod will preferably be carried out, since there is no need for disassembly and assembly by the user. This can be a coupling with high tightening and fixing power, for example a mounting with dilation of

The connecting rod by temperature rise, or by the use of retaining liquid of the anaerobic resin type of high residual resistance.

Finally, as regards the bowl and bearing system, the solution proposed here is to provide each bowl with a hemispherical cavity that seats a spherical section ring that in turn supports the bearing. Said ring will have the inner cylindrical surface adjusting to the bearing, and the spherical outer surface thus allowing the bearing to be oriented in any direction. This will allow whatever the positioning between both cups, conditioned by the irregularities of the bottom bracket of the bicycle frame, the bearings can always be perfectly aligned. Once aligned, the own preload of the connecting rods on the bearings will ensure the positioning of two supports.

BRIEF DESCRIPTION OF THE FIGURES

• FIG. 1 is a perspective view of the crankset and bottom bracket objects of this patent, assembled in the part of the bicycle comprising the bottom bracket.

• FIG. 2 shows the previous set that has been removed from the bicycle, the connecting rod on the side of the transmission is loose and the opposite one comes out integral with the axle.

• FIG. 3 shows decoupled, the parts that intervene in the sliding joint that makes solidarity in FIG. 2 to the crank shaft assembly. • FIG. 4a and 4b correspond to a sectional view of said sliding joint in two different adjustment positions.

• FIG. 5 corresponds to the plan view of the opposite connecting rod next to the plates.

^m FIG. 6 shows the two basic steps in the production of this connecting rod when machining from a bar: lathe and milling.

• FIG. 7 shows the three parts that make up the connecting rod on the side of the transmission disassembled: crank arm, spider and nut.

• FIG. 8 in a bottom plan view of this connecting rod, shows what the drag profile for the spider is like.

• FIG. 9 shows a bowl and corresponding bearing and bearing spherical ring.

- FIG. 10 is a sectional view of the bottom bracket support assembly, showing both cups facing and misaligned, where it can be seen how the bearings remain aligned.

• FIG. 11 is a profile view of the assembly of FIG-I, showing a cut line corresponding to the section of FIG-12.

• FIG. 12 is a sectional view of the previous assembly according to that cutting line.

"FIG. 13 shows a connecting rod axle clamp screw that incorporates a clamping lock.

DETAILED EXHIBITION OF A PREFERRED MODE OF EMBODIMENT

The proposed embodiment is actually the sum of several mechanical solutions that affect the cranks and the bottom bracket of the bicycle.

The bottom bracket (3) has a spline of cylindrical generation (38) at its left end, without close limits that prevent the sliding of its corresponding connecting rod (1) in both directions, for its subsequent adjustment to the actual measurement of the bottom bracket (0), so as to avoid both possible axial clearance and excessive axial load on the bearings. At its right end, however, it will have an insert without such a degree of freedom, which in this case is tapered (39) for less suffering from wear - or even chip removal as occurs in many cylindrical inserts - in each disassembly operation and assembly of its corresponding connecting rod (2).

For axial adjustment between the left connecting rod and the shaft, which allows varying the final distance between connecting rods, the use of a single screw (8) with double thread is proposed. Said screw can be defined as a threaded body with a threaded head, the thread (83) of the body of the pitch screw being significantly greater than the thread (82) of said head. Specifically, in Figure 4, the thread of the passage body being 1.5 mm and the head of 0.5 mm, for every two left turns of the screw (8), the shaft (3) will distance 2 mm of the connecting rod (1), while the screw, in the opposite direction, will only do 1 mm. Both threads have the same direction of rotation, the screw entering the shaft and the connecting rod from the outside, since it is convenient that the diameter of the head be of a diameter substantially greater than that of the body having a shorter length.

With all this, the crank and axle assembly will be presented in a "semi-integrated" shaft configuration. That is, a disassembled connecting rod of the shaft - which is somewhat generalized - in this case the right connecting rod (2), and the other, the left one (1), will be integral with the shaft but with an advance recess adjustable by means of said screw ( 8) double thread. In this way, the distance between connecting rods can be manipulated without sacrificing a high-tightening shaft-crank adjustment and the sliding insert is prevented from degenerating during the disassembly-assembly operations.

Regarding the connecting rods (1 and 2), a solution is proposed in which it is based on high strength aluminum alloy in round extrusion bar, since it has excellent mechanical properties thanks to the orientation of the fibers. Said bar is machined on the lathe to achieve the preform (the) whose revolution profile is the outer profile of the connecting rod, and it is drilled to achieve the desired cavity (10) - without going through this hole the whole piece -. As the entire piece is parallel to the direction of the metal fiber, oriented in the extrusion direction, the high properties of the source metal are ensured. Said preform has at its only end to drill a protrusion that once the hole is formed forms a ring (11), essential reinforcement for this opening. It is therefore a straight rod in its primitive form.

Subsequently, it is machined by milling to reach its final shape (1 or 2 in each case).

At the beginning of the hole (10) it is proposed to practice a threading that allows the placement of a plug (11), which in addition to covering the hole, for cleaning and aesthetics, could serve to reinforce the shaft-rod-screw fixing (3- 1-8, or, 3-2-9).

In the case of the right connecting rod (2), it will have a mechanized recess thus forming a drive gear (222) to couple the corresponding spider (22), in charge of coupling plates for chain transmission, and will also have necessary thread for the locking nut (23) of the spider. Said gear profile will affect only the lateral flanks of the connecting rod (2), so as not to interfere with the hole it passes through.

The use of a double-threaded screw for the assembly of the right connecting rod is also proposed, rather by maintaining a symmetry of understanding for the user of what occurs in the opposite connecting rod, although it also allows to save some weight, providing greater fineness of manipulation and greater security to prevent the screw from loosening, thanks to the reduction of the thread pitch. In the design, the thread of the body of the screw is of 1 mm pitch and that of the 0/5 mm pitch head, which gives an advance per revolution of 0.5 mm between the shaft and the connecting rod.

As for the bottom bracket support assembly that includes the bearings, an external bearing system is proposed compatible with existing integrated connecting rod systems, but with the particularity that each bearing (43) sits on a carrier ring (42) with an outer surface spherical which acts as a patella with a spherical cavity practiced in the bowl (41). This will allow whatever the positioning between both cups (41 and 41 '), conditioned by the irregularities of the bottom bracket (0), the bearings (43 and 43') can always be perfectly aligned. Once aligned, the preload itself in the assembly of the connecting rods on the bearings will ensure the positioning of two spherical carrier rings.

OTHER POSSIBILITIES

Each of the above solutions is valid separately. In particular, the use of a semi-integrated shaft can be a very effective solution in the case of carbon fiber connecting rods, which until now maintain a fixed distance between connecting rods; the cranks hollowed by means of a drill with a reinforcement ring in the crank head are a simple solution in themselves to save weight; and the self-aligning cups are valid for any other connecting rods with external bearings.

As a locking fastener for double-threaded screws (8) or (9), a safety screw (88 in FIG-13) can be used to house its head and through it, so that it could be tightened to brake a Once the double thread screw reaches the desired position. This safety screw could also be placed in different angular positions of said head, for example 8 regularly spaced possible housings, which, combined with the nine splines (18-38) for anchoring the shaft, allowed a fine adjustment where the safety screw could easily - every 2'5 ° - combine one of its possible housings with one of the grooves then making a function of a latch and not a brake. With this solution, double threaded screws can be an ideal solution for all types of shaft-connecting rod sliding anchors even if it is not a high tightening assembly.

Another connecting rod corresponding to this invention would also be constructed from a recessed connecting rod by means of the drill described above, to which the connecting rod arm is wrapped with a carbon fiber and resin sleeve, resulting in a hollow aluminum connecting rod, with a composite lining.

Claims

1) A bicycle pedal axle, which from the first of its ends maintains a diameter that is always smaller than or equal to the one along the axis where the corresponding bearings give radial support, thus being free of any restrictions that prevent its axial displacement in its support at least towards said end, and whose second end has an anchor that allows a connecting rod to be connected, characterized in that said first end has a cylindrical drag profile for the sliding anchor of a second rod, so that said anchor allows the final distance between the connecting rods can be increased and reduced with respect to the nominal distance between the two.

2) An integrated axle pedal pedal assembly, comprising an axle and its corresponding connecting rods forming a unitary commercial product, in which the axle is factory assembled to one of said connecting rods, characterized in that said axle corresponds to that of the Ia claim 1 allowing the depth of the insert between it and the connecting rod that integrates it is variable.

3) A crankset and bottom bracket screw, applicable to the engagement between said connecting rod and a bottom bracket, where the screw has a cylindrical head and body, characterized in that said head of the screw is provided with an external thread in the same direction of rotation and of a passage substantially smaller than the passage of the body thread, and because said connecting rod disposes, in a manner adjacent to the housing for inserting the shaft, the thread corresponding to said threaded head.

4) A crankset and bottom bracket screw according to claim 3, characterized in that said threaded head screw accommodates in its head a safety screw that through said head acts as a brake when coming into contact with the connecting rod.

5) A crankset and bottom bracket screw according to claim 4, characterized in that said threaded head screw has multiple housings in its head for said safety thyme. 6) An integrated shaft bottom bracket assembly according to claim 2, characterized in that in order to vary the depth of the insert between the shaft and the connecting rod that integrates it, it makes use of a screw with cylindrical and threaded head and body, the Ia screw head threaded in the same direction of rotation and with a step substantially smaller than the passage of the body thread, and because said connecting rod disposes, adjacent to the housing for shaft insertion, the thread corresponding to said thread of Ia screw head

7) A bicycle connecting rod provided with a hole made at the end of the connecting rod opposite to which the pedal anchor corresponds and which extends along the crank arm defining a hollow connecting rod, characterized in that at the entrance of said hole , The connecting rod has a protuberance or excess material, so that around said hole said protuberance forms a reinforcing ring.

8) A bicycle connecting rod according to claim 7, characterized in that it is made of aluminum alloy starting from an extrusion profile, which is first machined on the lathe respecting said protuberance at its corresponding end and drilled to form said hole, and subsequently Finish machining by milling.

9) A bottom bracket support assembly for the assembly of integrated bottom bracket systems in the bottom brackets of the bicycles, which comprises two bearings that are located on both sides on the outside of said bottom bracket by means of cups, characterized by that each of said cups is provided with a spherical cavity that seats a ring which in turn is the one that supports the corresponding bearing, said ring having the cylindrical inner surface adjusted to the bearing, and the spherical outer surface, allowing the bearing to be oriented within the bowl with a certain margin capable of overcoming any irregularity of said bottom bracket that positions said cups in an unaligned manner.

10) A connecting rod according to claim 7 characterized in that it is covered with a sleeve made of carbon fiber composite material. 11) A connecting rod according to claim 8 characterized in that it is covered with a sleeve of carbon fiber composite material.