FR2520693A1 - Gear change chain guide for bicycle - has pivoted moulded plastics arms with reinforced areas engaging chain - Google Patents

Abstract

The chain guide for a bicycle is used to change gear speeds and has an arm and a counter arm carrying pivot axes to allow displacement laterally to change gear. Rollers are mounted for free rotation between the arms to guide the chain. The two arms are moulded from plastics and have thickened areas where extra strength is required. The thickened areas have smooth transitions to the normal thickness of the arms. The arms can have central thickened area corresponding to the surfaces engaging the chain on either side when guiding it.

Description

 The invention relates to a roller chain guide for rear speed changes of cycles i similar vehicles.

As a corollary, within the scope of the invention, the gear changes comprising this guide bar.

 The object of the invention relates in particular to the technical sector of accessories and equipment for cycles and similar vehicles.

 The rear gear changes of bicycles and similar vehicles are essentially constituted by a parallelogram system, or with a sliding axis, or otherwise, which transversely displaces a roller guide guide with respect to the stepped pinions integral with the hub of the rear wheel.

 The guide bar is generally constituted by a flange (closest to the frame) and a counter flange (the furthest from the frame) between which are mounted free rotation one or more rollers on which the chain is supported, rolls up and kept taut.

The flange and the counter flange are generally made of metal and more particularly of light alloy, by cutting - stamping most often.

 The die-stamped design of the metal flanges is not without presenting some drawbacks, for example the fact that, during manufacture, variations in dimensions can occur as a result of misadjustments due to the tools. This leads to costly rejects, or even operational problems when you do not notice the irregularities.

On the other hand, the flanges and counterflanges obtained by stamping are of constant thickness. If you want to change their thickness at certain points, you have to cut them and stamp them, which is more complicated and clumpy.
The flange and the counter flange of the guide rail according to the invention are characterized in that, on the one hand, they are made of molded plastic, while, on the other hand, they have characteristics specific and advantageous to their realization, which makes it possible to obtain dimensional security and an almost absolute manufacturing constancy, while having an economical execution.

 Importantly; the molding allows all variations of shapes, dimensions and arrangements of the flange and the counter flange, depending on the operating conditions.

According to a first characteristic, the flange and the counter flange are made in a combined manner, in plastic material and have, according to predetermined functional zones, one or more profiled thickeners and progressively connected with the general thickness, in order to economically obtain flanges and light, silent, unalterable and reliable counter flanges0
These and other features will become apparent from the description which follows.

To set the subject of the invention without however limiting it, in the accompanying drawings
Figure 1 is a perspective view showing a non-limiting example of embodiment of rear gear change mounted on the axis of the rear wheel of a bicycle. The flange and the counter flange of the guide bar have been illustrated in strong lines.

 Figure 2 is a view along arrow F of Figure t, illustrating the chain guide according to the invention.

 Figure 3 is a perspective view separately illustrating the different 'elements of the chain guide.

 Figures 4b 7 are sectional views taken respectively along lines 4-4, 5-5, 6-6 and 7-7 of Figure 3, illustrating different sections of the counter flange.

 Figure 8 is a large-scale sectional view illustrating a first embodiment of the mounting of a roller between the flange and the molded counterflange.

 Figure 9 is a sectional view on a large scale illustrating a second embodiment of the mounting of a roller between the flange and the molded counter-flange.

 FIG. 10 is a front view illustrating a dust cover bowl arranged to cooperate closely with the coated counterflange, as shown in FIG. 9.

 FIG. 11 is a partial view in section and on a large scale, illustrating two other embodiments of the counter-flange fitted at the level of the mounting of a roller.

 Figure 12 is a partial sectional view on a large scale, illustrating another arrangement of the counter flange at the mounting of a roller.

 Figure 13 is a partial sectional view on a large scale, illustrating another embodiment of the flange at its mounting on the lower yoke of the gear change.

 In order to make the object of the invention more concrete, it is now described in nonlimiting embodiments illustrated in the figures of the drawings.

 As a reminder, there is illustrated in Figure 1, the rear part of a bicycle frame and more particularly the ends of the shrouds (H) and the bases (B) carrying the lugs (P) for fixing the hub (M ) of the other wheel with its free wheel (R). A gear change (V) of the deformable parallelogram type is mounted with elastic articulation by a lug (V1) or other means on the axis (A) of the rear wheel.

 The gear change illustrated mainly comprises an upper yoke (V2) and a lower yoke (V3) connected by two links (V4 - V5), in order to constitute the deformable parallelogram intended to move the chain (C) transversely with respect to the freewheel axis.

 Other members, such as members for guiding and fixing the control target and members for adjusting the amplitude of the movement, are also provided in known manner.

 The lower yoke (V3) has an axis (V6) with concentric coil spring and located inside the yoke, .. the end projecting from the side of the frame of the bicycle is equipped to receive in a known manner a guide in (G) in the drawings, bearing free rotation of the rollers (G1 - G2) of winding, in tension of the chain.

 The guBe-chaSne according to the invention comprises a flange (1) on the side closest to the frame and a counterflange (2) on the side furthest from the frame. The flange (1) is mounted on the axis (V6) of the lower yoke, the projecting part of which has a thread (V7) as illustrated in FIG. 13, for screwing the flange (1) and a lock nut. (VS).

 The counter-flange (2) is connected to the flange (1) via the free-rotation mounting axes of the rollers (Gi - G2) which are generally constituted by screws (3).

 According to the invention, the flange (1) and the counter-flange (2) perforated are economically made of plastic so as to be able to obtain precise sizing had a consistency of manufacturing almost absolute. The plastic must be noble, for example an acetal resin.

 According to an important characteristic, the plastic material of the flange and the counter-flange makes it possible to adapt the cross-sectional shapes of their various parts according to the mounting and operating requirements.

 Firstly and according to a first characteristic, the counter-flange (2) has a central zone reinforced (2a) by an excess thickness of material (hatched zone, FIG. 3). This additional thickness is progressively connected with the general thickness as well shown in FIGS. 4 to 7 of the drawings illustrating four particular sections of the counter-flange (2).

 This reinforced z8ne (2a) corresponds to a surface which can be drawn from the chain when the guide rod is moved away from the frame / must pass the chain over a freewheel pinion of smaller diameter. The flange (i) can also have a similar zone for the thrust of the chain when the chain guide is e that one approaches the frame / must pass the chain on a freewheel sprocket of larger diameter. Of course, this extra thickness of material is located outside the flange and the laser backing plate.

 According to another characteristic, the counter-flange (2) has, at the level of the mounting of the rollers and the fixing with the flange (1), another reinforced or oversized zone (2b) extending outside the counter -flange and profiled in spherical cap with wide connection with the general thickness or with the central reinforced zone (2a).

 As best seen in Figures 8, 9 and 11, the extra thickness of material (2b) increases the width of the screwing surface. of the screw (3) which very significantly improves the resistance to the screwing torque of the screws, by the large number of threads in engagement.

 On the other hand, it is important to note that the mounting holes of the threaded part of the screw (3) are economically obtained directly from molding without tapping when resuming machining; the screw (3) is self-tapping, and the screw self-brakes by clamping effect on the plastic.

In another characteristic illustrated in FIG. 11, the width of the screwing range is further increased by the production of an internal chimney (2C) on the counter-flange (2) around the smooth hole for mounting the screw. In this case, the axial spacer (4) which is interposed between the screw (3) and the roller (G1 or
G2), has a recess (4a) for the passage of the chimney.

it is understood that the chimney (2c) can be made also to replace the extra thickness (2a).

 According to another characteristic illustrated in FIGS. 9 and 10, the production of the flange (1) and the counter flange (2) made of plastic material makes it possible to incorporate the dust covers (5) which are engaged by their peripheral edge (5a) into the molding. forming a bowl, in circular and lateral grooves (G3) of the rollers.

 To this end, the dust covers (5) have tabs (5b) cut and folded obliquely or in an inclined manner to be embedded in the thickness of the flange and the counterflange having good resistance to tearing.

 It is understood that with a flange or counter-flange assembly and integral dust covers, the mounting of the qalets is increased, easier and more economical.

 According to another characteristic linked to the manufacture of the plastic flange and counter-flange, provision is made to remove the added metal dust covers and to replace them with a bowl (Id - 2d) produced during molding with the flask and the counter flange -figure 11), This cup cooperating with the grooves (G3) of the rollers.

 Of course, this embodiment may or may not be combined with the chimney (2c) or with the additional thickness (2b).

 It is also possible, as illustrated in FIG. 2, to drown in the molding of the counterflange (2) a metal insert n6) in the form of a sheet metal washer, for screwing both in the plastic material and in the sheet metal with a screw. (7) with spdciai thread ("Parker" type) or self-tapping.

 In this case, it is possible to remove the oversize (2a) in a spherical cap.

 On the flange (1), the use of plastic, does not allow the direct screwing of said flange on the threaded part of the axis (V7) because of the significant forces undergone at this level.

 To ensure a solid and reliable mounting, provision is made to screw the flange by means of a shouldered nut (8) which is either inserted during molding, or added into a shouldered cavity (la) of the flange whose thickness has been increased by a boss (lb), the shoulder (8a) of the nut being made polygonally for angular indexing.

 As can be seen in FIG. 13, the lock nut (V8) pressing against the flange (1), there is self-braking due to the plastic material.

 Near the axis (V7) of articulation of the guide-catne, one fixes outside the flange (1) a screw-axis (9) intended to serve as pivoting stop after tensioning, for the guide - chain relative to the lower yoke (V3) of the gear change (Figure 13). As for the screws (3) for mounting the rollers, the stopper (9) is screwed directly into a smooth hole in the flange (1) which has an additional thickness (lc) of the same nature as the additional thickness (1b), in order to increase the number of nets caught. In this way, the plastic material tightens around the threads, constituting self-braking.

 It should also be noted that the thickness of the flange can be reduced at its lower part of the wrapping of the roller to facilitate the disengagement of the rod as it is misaligned with respect to the crankset.

 On the other hand, for certain embodiments of a de amme, ncessi ant cooperating with chastes of different widths of different rollers, one can replace the spacing washers attached to the axial spacer (4), by bosses inside the flange and / or against the flange, thus retaining a single length of spacer.

 The advantages of the plastic flanges and counterflanges are apparent from the description. We also emphasize - The economic achievement by molding and the absence of threads and other machining resumptions.

- Almost absolute dimensional stability.

- The possibilities of increasing the thickness of the functional areas, in particular of the screwing zones, and of decreasing the channel clearance zones.

- The protection of the rear wheel shelving against unexpected contact of the counter flange, by the widely rounded extra thicknesses.

- Simplification and speed of assembly with metal dust covers integrated into the flange and counter flange, or formed directly in the molding.

- The lightness of the guide bar.

- The absence of wear of the chain compared to the guide bar.

- The removal of any protective coating against corrosion.

- Silence and flexibility of operation.

- Self-braking of the assemblies screwed by the effect of the plastic material in the screw threads.

- The possibility of making a folded edge (2e} of low thickness - only for protection against possible contact of the counter flange in the spokes of the wheel (folded edge which has been the subject of a Patent No. 2,225,327 including the applicant is also the holder), so that in the most unfavorable case, it is the folded edge which gives way, thereby avoiding breaking of the spokes.

 The invention is in no way limited to that of its modes of application any more than to those of the embodiments of its various parts having been more especially indicated, on the contrary it embraces all variants.

Claims (7)

-1- Chain guide with rollers for rear gear changes of cycles and similar vehicles, of the type comprising a flange (1) and a counter flange (2) carried and oriented with elastic pivoting on the system (V) of the transverse displacement of the speed change, between said flange and said counter flange being mounted with free rotation of the rollers (G1 - G2) for winding the chain (C), characterized in that the flange (1) and the counter flange ( 2) are executed in a combined manner, in plastic material and in that they have, according to predetermined functional zones, one or more profiled thickeners and progressively connected with the general thickness, in order to economically obtain flanges and counter light, silent, unalterable and reliable flanges. -2- Guide guide according to claim 1, characterized in that the flange (1) and the counter-flange (2) have externally a central zone reinforced (2a) by an excess thickness of material this excess thickness is progressively connected with the general thickness and corresponds to a support and pushing surface of the chain when the guide guide moves in one direction or the other. -3- Guide-chain according to claim Xcaractérisé in that the counter-flange (2) has externally at the level of the mounting of the rollers (G1 - G2) and of the fixing with the flange (1), a reinforced zone (2b) by an excess thickness of material profiled in a spherical cap with a large connection with the general thickness or with the central reinforced zone 42a), so as to increase the width of the screwing range of the screw-axis (3) of free rotation mounting of the pebbles. G2), the chimney being combined or not with the extra thickness (2b) to increase the width of the screwing span. -4- Guide guide according to claim 1, characterized in that the counter-flange (2) has internally at the mounting of the rollers (G1 - G2) and the fixing with the flange (1), a reinforced area ( 2c) in the form of a chimney, nested with an axial intermediate (4) interposed between the screw (3) and the roller (G1 or G2) are protected by dous couspères (5) engaged in circular and lateral grooves (G3) of the rollers, characterized in that the dust caches (5) have tongues (5b) cut and folded obliquely or inclined for other embedded in the thickness of the flange (1) and the counterw sque (2) having a good resistance to tearing. -5- Guide-chain according to claim 1 and according to any one of claims 3 and 4, including the axes of the rollers (G1 -6- Guide guide according to claim 1 and according to any one of claims 3 and 4, the rollers (G - G2) have circular and lateral grooves (G3), characterized in that the flange (1) and the counter flange (2) have internally and directly molding, bowls (ld - 2d) cooperating with the grooves (G3) to produce dust covers.  -7- Chain guide according to claim 1, characterized in that the flange (1) has proximitd an axis (V?) Of elastic articulation of the guide-catne on the transverse shifting system of the gear change, an external overthickness (lc) intended to increase the width of the screwing port of a screw axis (9) serving as a positioning stop for the guide bar (after tensioning) relative to the lower yoke (V3) of the gear change -8- Guide guide according to claim 1 and according to any one of claims 3, 4 and 7, characterized in that the threaded surfaces of the pins (3 and 9) are screwed directly into smooth holes produced by molding on the flange (1) and the counter flange (2), in order to obtain an auto effect = reinforcement of the screws by the plastic material. -9- Guide guide according to claim 1, characterized in that the flange (1) has externally at its mounting on the axis (V7) of the lower yoke (V3) of the gear change, an extra thickness or boss (lb) of reinforcement, progressively connected with the general thickness or with the additional thickness (tic); a nut (8) shouldered and indexed in rotation being either inserted during molding, or attached in a shouldered cavity (la) of the flange, for screwing the flange on the threaded part of the axis (V7), and a lock nut ( V8) mounted between the flange. and the lower yoke (V3), being applied in elastic pressure against the flange (i).  pendant / their width. -10- Guide guide according to claim 1, characterized in that internal bosses are provided on the flange and / or the counter flange at the level of the mounting of the rollers (G1 - G2) in order to use a single axial spacer ( 4) mounting the independent rollers -11- Chain guide according to claim 1 characterized in that the flange (1) has internally at the lower enveloping portion of the lower roller, a reduced thickness to facilitate the release of the chain when it is misaligned.