WO2008107498A1 - Bicycle handlebar stem including an attachment system comprising threaded clamps with different screw pitches - Google Patents

Abstract

The invention relates to a bicycle handlebar stem and to the attachment system thereof, which renders same very light. The invention mainly involves the use of clamps having threads on both sides of the opening, which require conventional screws to be replaced by double-threaded studs, the head of the conventional screws being replaced by a thread at the corresponding end, wherein said thread has a different screw pitch to the main thread of the screw. As a result, the tightening torque is greatly increased and the corresponding tool can be sufficiently small so that the recess is small and can be accommodated in the stud. The use of said screws reduces the weight of the actual screws and reduces the stress on the clamps; consequently, the clamps are lighter and more secure.

Description

 POWER OF HANDLEBAR FOR BIKES WITH SYSTEM OF FIXING BY CLAMPS WITH POTENTIATED THREADS

The present invention, applicable to bicycles and in general to any field of mechanics where lightness acquires an extreme importance, affects in particular the power, structural element that supports the handlebar, making it integral with the steering tube and with this to The front fork; and in general to clamp anchoring systems. Here, improvements aimed at lightness are collected without in any way affecting the reliability and structural properties.

STATE OF THE ART

The power in a bicycle is an element, usually with a tubular shape, which connects the handlebar with the front fork, which supports the wheel. The fork is attached to the bicycle through one of its ends which we call steering tube, connected to the frame of the bicycle by means of corresponding bearings in such a way that they allow it to rotate. The end of said steering tube projects from the frame of the bicycle sufficiently to allow the anchoring of this structural element that we call power. This, at one end embraces the end of the steering tube, and on the other side has a semi-cylindrical cradle to support the handlebar, which gives fixation by using a removable front bracket, also semi-cylindrical, which holds with screws to the main body of the power. At the end corresponding to the steering tube, the power has a clamp that we will call "steering collar", this being equivalent to a slotted tube able to embrace the steering by means of screws that close said groove. Said collar is integral with the main body of the power.

Thus the power is composed of main body, front clamp and screws, and in turn the main body could be defined as a rod that in its respective ends coupled to the steering collar and the handlebar support.

As for the axial fixation of the power in the steering tube. To this end, the steering tube is provided with a spider that is anchored inside it - or with an expander element that is also anchored to the inside of the tube -, which has a thread in its center. Once the power is placed in the steering tube, and always before tightening the steering collar, a cap is placed on it and by means of a screw that the said spider is screwed, the axial tightening of the same is carried out, and with this the final position of the power is regulated so that it tightens on the bearings of the steering, just enough to rotate freely but without pitching gaps.

Regarding the state of the prior art, no longer referring to the powers of bicycle, but the use of special screws with two threads that allow us the evolution of these powers that are described below, include: US83225 (from

1868), US2084146 and US5358367, which in general propose solutions of mechanical fixation with screws provided with two threads with different pitch, which combined with the corresponding nuts, achieve the union between two pieces with greater security or better adjustment than conventional screws; and the Spanish patent application

PCT / ES2007 / 000160, from the same inventor as the present one, where double-threaded bolts are used for the coupling of the bicycle axle-connecting rod, due to its drag capacity in both directions since they allow to easily regulate the depth of the shaft-connecting socket.

SUMMARY OF THE INVENTION

Given the extreme importance of weight in bicycles, improvements are proposed below aimed at achieving a lighter power, without renouncing rigidity and mechanical performance in general. In particular, it is proposed to use special clamps, provided with threads on both sides of the closing slot, for which use headless screws. In addition, a constructive improvement is also proposed that allows to improve the lightness of the main body of the power.

Said threaded clamps involve the replacement of the screws that tighten the conventional clamps, by screws without a head, which has been replaced by a certain length of threaded stud at its corresponding end, but with a thread pitch different from the main thread of the primitive screw.

These headless screws, or double-threaded studs, can also be defined as bolts with enhanced threads, because if the main thread is intended to be screwed into the main body of the power and the secondary thread in the front clamp, we will check that for every turn that we screw said stud, this to advance with different step in each piece, makes these pieces approach with a relative displacement equal to the difference between the steps of both threads. In this way and choosing the appropriate thread steps, a great multiplication of the tightening torque, which in fact makes the existence of the head of the screw unnecessary, since in order to carry out the task of fixing the screw it is sufficient to apply a reduced torque, the corresponding tool may be small enough so that the fingerprint of the screw drag, for example, the hexagonal slot for "Alien" key, is so small that it has room in the stud itself.

The fact of using these screws not only supposes a reduction of weight in the screws themselves having eliminated their head, but also supposes a lower stress in the clamp: the concentration of the effort just in the area where said head should be squeezing disappears , because that same force is now distributed along the length of the threaded surface in contact with the screw. Thus, it is possible to dispense with the clamp the extra material around the tightening zone, precisely intended to reinforce said area around the head of the screw. In addition to lightening the pieces where we apply these screws, it is possible to eliminate the main weak point where they normally end up breaking this type of work due to fatigue.

Particularly relevant is the use of the aforementioned threaded screws in the steering collar: since these screws have a reversible effect - that is, they open by turning them in the opposite direction to the closing one -, they facilitate the assembly and disassembly processes. This makes all types of clamps a particularly suitable application for this type of screws.

In this case, as it is a one-piece clamp, whose slot closes by the bending of the clamp, the screws will have to be assembled previously, preferably at the factory, by bending said clamp to the point that allows the screws to engage. Both threads and, once screwed, stay in a centered position when the slot reaches the design position. It could also make use of threaded inserts, which once assembled should be fixed in said collar or clamp.

Given the improvement in weight that these threaded screws provide, they can also be used for the axial fixation of the power in the steering tube. The conventional cap and screw assembly can be replaced by a cover provided with a thread with a pitch different from that of the spider and a screw with a double thread. With this in addition to the improvement due to the reduction of weight, thanks to the reduction, a much finer regulation of the tightening on the steering bearings is achieved. Finally, as regards the constructive improvement of lightening the main body of the power, said improvement affects exclusively the parts manufactured by machining, usually of high strength aluminum, and a cone-shaped design is suggested: starting from a diameter smaller from the tightening collar to the steering tube, and progressively opening towards the handlebar until it almost envelops it. This cone is emptied in the lathe, but making the wall thinner as the diameter increases towards the handlebar, the hollow in said cone and in this end behind the handlebar, of a diameter loosely larger than the diameter of the handlebar. However, the emptying will be such that already at the end corresponding to the handlebar, the recess closes, with the consequent final thickening of the wall, to end up with an internal diameter small enough to support the cradle. handlebar and house the threads that will later serve to assemble the clamp.

BRIEF DESCRIPTION OF THE FIGURES "FIG.1 shows the power as a whole, coupled to a steering tube and carrying a handlebar.

"FIG 2 corresponds to a view from the rear of the same power as a whole.

• FIG. 3 shows the main body of said power.

• FIG. 4 corresponds to a section of the power, cut made by the plane of symmetry of the handlebar.

• FIG. 5 shows the three phases of the anchoring of the frontal clamp to the body of the power: in FIG. 5, both disconnected; in FIG.5.2 both faced, to start screwing; and Ia FIG.5.3, both already screwed.

• FIG. 6 shows the steering collar on the back of the main body of the power.

• FIG. 7 shows the power complete a section by the plane corresponding to the clamping screws to the steering collar. In it you can see the double threads.

• FIG. 8 shows a similar section of a power that makes use of threaded inserts for the tightening screws of the steering collar. • FIG. 9 shows detail of one of the screws and its corresponding threaded insert, corresponding to the section of FIG. 8

m FIG. 10 shows in section, the lid-screw-spider assembly, for the axial tightening of the power.

"Figure 11 shows the assembly comprising a screw cap and a screw thread, in two tightening phases that could be considered as initial and final.

• Figures FIG. 12 and FIG. 13 show the two basic steps in the manufacture of the main body of the power when machining from a bar: turning (FIG 12) and milling (FIG 13).

DETAILED EXHIBITION OF A PREFERRED EMBODIMENT

A power is proposed whose front clamp (10) makes use of double-threaded screws (11, 11 ') for the fastening of the handlebar, and therefore said clamp is provided with threads. Regardless of the number of screws (11, 11 ') that are used to hold the handlebar, 2 or 4 is the most common, here we propose that the threads in the main body (0) of the power be of metric 6, with pitch of 1 mm, while in the clamp Io they are also metric 6 but with fine pitch, of 0.75 mm. In this way for each turn that we give to the corresponding screw, when it is screwed in both pieces (see Figure 5), it will advance 1 mm in the power and 0.75 mm in the clamp, resulting in a displacement of 0.25 mm of the clamp relative to Ia power. As the advance is so small, the necessary tightening force for the handlebar is achieved even when the screwing force is considerably less. For this reason, the screw drive trace is reduced so that it can be housed directly in the stud: with the metric stud 6 and the 3mm Allen footprint, or Torx T20.

For the tightening of the steering collar (1) however, metric threads 6, with a pitch of 1 mm, are proposed in the entry hole where the diameter is necessarily greater, and metric 5, with a pitch of 0.8 mm, for the opposite holes, which logically are of smaller diameter to allow the assembly of the screws (12, 12 '). This achieves an effective tightening step of 0.2 mm per revolution.

These screws of the steering collar must necessarily be assembled as a previous step to the placement of the power in the steering tube: normally said assembly will be carried out in the factory because it is part of the conformation of the product "power" or in its case, "clamp". According to said threads, as the thread pitch is greater in the inlet hole, as the screw advances, the slot will open - and vice versa -, so that to assemble them it will be necessary to first deform, by bending, said clamp closing Ia. slot as necessary, and then as you screw the screw, entering its working position, the slot will recover its original position, which in this case is necessarily ajar. Said deformation for the assembly will be approximately 1 '4 mm, equal to the number of threads of the thread of greater diameter - 7 in this case - by the resulting effective step - 0.2 mm -, although it will also depend on the design tightening, this is, the opening of the slot when the power is placed in the steering tube without the screws pull or push.

Since the screws open the slot as they are screwed in, as the passage to the entrance is greater than to the bottom, if the screws had right-hand threads, they would tighten the steering collar to the left; so to squeeze right, we will use threads to the left.

Regarding the axial fixation of the power, it is proposed to use a cover (14) provided with fine metric thread 6 (075 mm) and a screw with two threads (13): one of standard metric 6 (step 1mm) for the spider (15) and the other, the thread corresponding to said lid.

As for the construction of the main body, it starts with a 50mm diameter bar, which is turned to generate a rod (3) with a truncated cone shape, with approximately 31.5 mm for the smallest outer diameter, in

What will be the union to the steering collar, and 37 mm for the larger inner diameter, after the handlebar support (2), whose diameter is usually 31.8 mm. (Figure 12)

OTHER POSSIBILITIES

The use of clamps with threaded screws is applicable in many situations, especially whenever the weight or volume are predominant factors. Specifically within the bicycle there are other clamps where you can also make use of the described double threads, such as the derailleur - hinge clamp -, Ia of the seat post - slotted fixed clamp similar to the collar of address -, both with perimeter layout. Likewise, the brake levers and the shift levers, the handlebar couplings, etc. are clamped.

In addition to the field of the bicycle, many other components that use semicircular clamps - such as the front clamp described - or perimeter - such as the steering collar - can also take advantage of the use of this type of double-threaded bolts, for example in the connecting rod heads of the reciprocating engines, where the connecting rod embraces the crankshaft journal.

Claims

1) A handlebar power for bicycles, which is composed of a main body (0), a front bracket (10) and screws; characterized in that said clamp has threaded holes, and the screws (11, 1 1 ') that connect said clamp to the main body, are studs provided with two different threads, corresponding to two different thread passages, one of them intended to screw on the main body of the power, and the other to screw on the front clamp. 2) A handlebar power for bicycles, which is composed of a main body, a front bracket and screws, and whose main body consists of rod, steering collar and handlebar support; said steering collar having a groove and corresponding holes on both sides thereof to be closed by screws (12, 12 '); characterized in that said holes are threaded with two different threads, one on each side of the slot, said threads having different diameter and thread pitch, and the screws that give closure and tightening to said collar, are studs provided with the two threads corresponding. 3) A handlebar power for bicycles, which is composed of a main body, a front bracket and screws, and whose main body consists of rod, steering collar and handlebar support; said steering collar having a groove and corresponding holes on both sides thereof to be closed by screws, the holes being screwed to only one side of the slot; characterized in that the holes, where they are not threaded, incorporate threaded inserts, the thread of which is different from that of the said threaded holes, and the screws that give closure and tightening to said collar, are studs provided with the two corresponding threads. 4) A regulation system for the tightening of handlebar powers on the steering set, formed by cover (14) and screw (13), which are mounted after the power, just at the end of the steering tube (21), characterized in that said lid is provided with a thread, and said screw is a stud with two threads, one of them with a different pitch to said lid. 5) A system of mechanical fixation by means of cradle, semi-cylindrical clamp and screws; characterized in that said clamp has threaded holes, and said screws are studs provided with two different threads, corresponding to two different ones Thread passages, one of them destined to screw in the cradle, and the other one to screw in the clamp. 6) A mechanical fastening system by clamp, with slot and corresponding holes on both sides of this to give closure by screw; characterized in that said holes are threaded with two different threads, one on each side of the slot, said threads of different diameter and thread pitch, and the screws that give closure and tightening to said system, are studs provided with the two threads corresponding. 7) A mechanical fixing system by hinge clamp, with corresponding holes at both ends to give closure by screw; characterized in that the corresponding holes are provided at each end with different threads, corresponding to two different thread passages, and the screws that give closure and tightening to said system, are studs provided with the two corresponding threads. 8) A mechanical clamping system, with an opening and corresponding holes at both ends, being threaded at only one of said ends; characterized in that the hole at the other end is provided with a threaded insert, with thread pitch different from the previous one, and the screws that give closure and tightening to said clamp, are studs provided with the two corresponding threads. 9) A power for bicycles that is composed of a main body, handle clamp and screws, and whose main body consists of rod, steering collar and handlebar support, and where said rod is manufactured by lathe machining, being truncated cone Ia outer shape of said shank, with increasing diameter towards said support, and whose interior is emptied in the winch in such a way that the thickness of the wall forming said shank decreases in the direction of the handlebar support; characterized in that the gap corresponding to this recess, behind said support, becomes loosely larger than that of the handlebar, so that in order to be able to form said handlebar support, said recess is closed, forming a smaller inner diameter at this end to the handlebar.