CH95931A - Back-pedal control device for single-chain, multi-sprocket gear changes for bicycles. - Google Patents

Description

Back-pedalling control device for gear changes. single-chain, multi-sprocket gears for bicycles. In single-chain, multi-sprocket gearshift devices employed in generally by the translation of a special pinion, the movement in one direction or the other is usually controlled by rigid rods, cables or other types of rigid or flexible transmission controlled by a lever within easy reach of the cyclist.

The object of the invention is a control device by back-pedaling of the above-mentioned gear changes which eliminates any kind of control transmission.

This device is characterized by the fact of using the chain itself to act directly by back-pedalling, on the usual sliding sprocket, then operates in the opposite direction to the normal direction, so that this sprocket arms a mechanism producing, Tors 'from the return to normal operation, the desired translation of the sliding sprocket and thereby the movement of the chain from one sprocket to another.

The appended drawing repi, esente, ä, by way of example, a form of execution of this object. Figs. 1 and 2 are exterior views in elevation, respectively in profile and in front; fig. 3 represents, in part, part in section and part in elevation, the assembly of the mechanism which facilitates the translation of the displacer sprocket of the chain; fig.4 is a cross section along E-E of fig. 3; fig. 5 is a schematic front view of this mechanism, two of the organs have been removed; fig. 6 is a section similar to FIG. 4 showing the mechanism for controlling the translation in another position; the figs. 7 to 10 are views similar to FIGS. 4 and 5 showing the aforesaid mechanism in different positions; ]es figs. 11 and 12 show a detail of this mechanism from the front and from the side respectively.

In this example, the gear change comprises three sprockets of different teeth 1, 2, 3 mounted in the usual manner on the hub a of the rear wheel r of the bicycle.

The sliding pinion b' intended to carry out by its translation the lateral displacement of the chain c on the sprockets 1, 2, 3 of the speeds, is mounted on a smooth axis e comprising an end e', serving to fix it to the support usual s, by means of nut and counter-nut s' s".

This pinion b', came in one piece with a sleeve b, which has two parallel collars b" on the inside, the rounded outer face of which constitutes a half-raceway for two ball bearings x<I>x.' </I> (fig. 3). At a point of the annular groove existing between the two flanges b" is arranged a ratchet tooth L, the tip of which is flush with the edge of the flanges (fig. 4).

The smooth surface of axis e is cut, on the one hand, along its length and along its generatrix, by a straight groove D, running over a determined length of this axis, and whose section is similar to that of the hollow of the teeth of ratchet, and on the other hand, on its periphery, of a groove H, formed of two helical portions meeting and constituting an endless groove, these two helical portions having a pitch equivalent to the distance existing between the pinion 1 and pinion 3.

On this smooth surface e is fitted with a slight play a sleeve f of length less than that of said surface e. This sleeve comprises at (you determined point of its length a flange .ii which serves as a half-raceway for the ball bearing x. On the other hand the surface of said sleeve is notched with an annular groove G and its wall is cut of three rectangular windows A. B C, opening into the groove G; the angular distance between the windows A B and between the windows B C is equivalent to 90 , while the distance between the windows A and C is equivalent to 180 (fig. 4, 6, 7 and 9). One of the two edges of these windows, which are parallel to the generatrix of the solid cylinder e, is on an inclined plane, for the purpose which will be described later. A screw o is located in a determined surface of the sleeve f. It passes through the wall of the latter and its point protrudes inside this sleeve, in order to be able to be housed in the hollow of the helical groove G of the axis e.

After the installation of this screw o, the sleeve f can no longer be separated from the axis e, on which it can turn with gentle friction and slide at the same time.

On said sleeve is mounted a ring Ia (fig. 11 and 12). In the wall of this ring are cut two slots of different dimensions. One receives a mo bile tooth ii, articulated by its heel in îz' and com bearing a read read arranged to maintain the tip of this tooth constantly projecting from the periphery of said ring. In the other slot is housed a dog i, formed by a curved piece articulated by one of its ends in j, and comprising at the opposite end a beak i, the tip of which protrudes inside the ring under pressure a leaf spring r', housed in a groove hollowed out inside the ring h. This dog has ni) protruding heel i, which is intended to fit into the hollow of the annular groove C belonging to the sleeve <I>f,</I> in order to prevent the bagne lz from separating from said sleeve when it was mounted on it, but while allowing it to rotate freely around this sleeve.

Finally, the crown of balls x is placed, then the sleeve b, then the second crown of balls .r', and finally the half-cup W, which is screwed onto the end of the sleeve f and is used to hold the whole in place and adjust the bearing.

The device thus constituted is completed by the usual tensioning device consisting of the return spring t, acting on the lever d', articulated on the axis e, and carrying at its lower end the small return pinion d (fig. 1 and 2).

The operation of the device is as follows: Assuming that the chain c is on the small sprocket 1 corresponding to the maximum speed, the sliding sleeve f and the parts it supports are in the position shown in fig. 4 and 10. The screw o constituting the guide pin of the sleeve f is located at the upper part of the helical groove or cam track G (fig. 10). The hook or dog i' crosses the window .-i and its point is hooked in the groove D. In this position the. hammer does not protrude beyond the outer diameter of the ring 7z and allows the complete rotation of the sleeve b, around this ring in the direction of the arrow A V (fig. 4). Indeed, when the sleeve b is driven in this direction, its fixed inner tooth or stop G slides on the periphery of said ring h without. meet any other obstacle than the mobile tooth n, but given the orientation of the latter; this abutment l passes over the inclined back <B>of</B> this tooth and makes it lower inside either housing by rotating around its axis against the aptagonist action of the spring ni. The movable tooth is. raises immediately after the passage of the fixed stop 1, with each turn of the sleeve b. As the hook i' has always remained engaged in the groove D, the penal colony la cannot be driven by the socket when the latter rotates in the <I>AV,</I> direction which corresponds to the forward movement of the bicycle. It follows that the socket b and its toothing b' <I>res-</I> will remain in the position shown in FIG. 10 as long as the cyclist pedals in the normal direction and wants to increase the high walking speed.

If, on the contrary, the cyclist wants to change gear and go to the minimum speed, which is given by pinion 3, he will back-pedal to print the chain and the sprockets on which it is located, titi movement in the opposite direction. In this reverse rotation of the sleeve b, its abutment <I>l</I> comes to meet the front of the mobile tooth n (fig. 4), which cannot be lowered when it receives a pressure of opposite and on the contrary constitutes a buffer. This results in the ring <I>h</I> being dragged by the sleeve b, in the direction of the arrow A 1i (fig. 4). In this rotation of the ring, the tip of the hook i first slides on the bottom of the groove D and, as the latter is sloping, it forces the said hook i' to rise so that its tip reaches the beveled edge of the window A and also follows this second slope to reach the outer surface of the sleeve f on which it slides. The resistance offered by this sleeve, the pin o of which is at dead center in the cam track H, must be much greater than that offered by the ring h so that the sleeve b can drive the ring alone and leave the sleeve immobilized. This resistance is obtained by operating a continuous pressure on the internal surface of this sleeve by means of leaf springs interposed between <B>there</B> internal surface of this sleeve and the external surface of the axis e, and making the office of brakes whose power is calculated according to the resistance to be obtained.

When the point of the hook ï in its retrograde course A k arrives at the window C of the sleeve f; it engages in this opening, and the tension of its <I>ni</I> spring throws it violently on the surface of the axis e, producing a clicking noise which indicates to the cyclist the encounter of a first notch by the hook. This notch is notch C which corresponds to the position to be given to the device to obtain the minimum speed.

At this moment, the cyclist ceasing the reverse pedaling and resuming normal pedaling, the first pinion b' is again urged to turn forwards. The back of the abutment 1 then wedges against the outer corner of the hook i, which protrudes from the periphery of the ring 1a (as shown in FIG. 6). It follows that the pinion sleeve b <I>b'</I> drives this ring in the normal direction represented by the arrow d V; and that said ring drives either in turn (in the same direction) the sleeve f via the hook i', which is only applied against the right edge of the window B (fig. 6) where the sleeve f has already turned a quarter turn in the AV direction.

This sleeve therefore takes around the axis e a rotational movement, and at the same time titi translational movement, which is determined by the displacement of the pin o in the helical path H. When the tip of the hook i reaches the groove <I>D,</I> it goes down the slope and comes up against the tops of this groove, where it stops and determines the complete immobilization of the sleeve f and the ring h (position shown in fig. 5 and 9). If we compare Figs. 4 and 10, we can clearly see the longitudinal travel accomplished by the sleeve f. This translation stroke along the axis e is equal to the interval existing between the pinions 1 and 3; so that pinion b' is in the plane of pinion 3.

In its translation movement which is very rapid, sprocket b' causes chain c to jump abruptly from above sprocket 1 and moves it laterally as far as sprocket 3, in whose teeth the gaps of the chain engage with them. themselves as a result of the continued rolling of this chain. The placement of said transmission chain on pinion 3 therefore determines the operation of the cycle at the minimum speed.

If the cyclist wishes to pass now to the average speed, he operates a new back pedaling to produce the effects previously described and to bring the hook i', which is in the window C (fig. 9) to engage in window B, then he stops back-pedalling and resumes forward motion, which determines a new drive of the sleeve by simultaneous rotation and translation and finally brings said sleeve to the position shown in fig. 7 and 8 after completing a race of half the value of the previous one. Sprocket b' is at this moment in the plane of sprocket 2 and a was jumping the chain from above sprocket 3 to transport it onto said sprocket 2 and carry out running at medium speed.

To pass from this medium speed to the high one, the same operations are repeated, so that the hook i', which is in the window<I>B</I> and on the spline<I>D</I> can come into the window A and have the sleeve f bare quarter-turned to bring it to the position shown in fig. 4 and 10.

The device is established so that the chain c passes gradually from one sprocket to the other in increasing speeds, that is to say from sprocket 3 to sprocket 2 and from sprocket 2 to sprocket 1, while for speeds the chain goes directly from sprocket 1 to sprocket 3 without stopping at sprocket 2. In the first case (increasing speeds) the value of the rotary displacement of the sleeve f in direction 3 y' is a quarter of a turn for each change of speed, while in the second case (decreasing speeds) the value of this displacement of the sleeve /' is half a turn. As for the translation or longitudinal displacement of this sleeve f on its axis e, its value is due to the pitch of the helical groove H, in which the lug o moves. This lug therefore completes half the path of groove H. IT goes in the direction of the arrow (fig. 10) and goes from position 02 of this figure to position o of fig. 5 when it comes to transporting the chain c from sprocket 1 to sprocket 3. The travel of said lug is limited to a quarter of the way of this same groove, that is to say from o to o1 (fig. 8 ) and from 0l to o (fig. 10) in the direction of the arrows when the chain must descend a first time from sprocket 3 onto sprocket 2 and a second time from sprocket 2 onto sprocket 1.

It is possible to transport the chain c from sprocket 1 to sprocket 2. To do this, the back-pedaling must be sufficient for the ring h to complete three quarters of a turn in the direction .À R and for the hook i' to start from the window<I>A</I> (fig. 4) to snap to window B via window C without stopping there. Returning to normal pedaling, sleeve f performs three quarters of a turn under the action of lug o which starts from position 02 (fig. 10) in the direction of the arrow and passes through position o (fig. 5) to go to position o1 (fig. 8) and stop there. The sleeve f and the pinion sleeve b b' therefore slide on the axis e from one end of the latter to the other, first from the position represented in fig. 10 to that shown in fig. 5, then they then return in the opposite direction until halfway to immobilize themselves in the position represented in FIG. 8 and 1. The chain c is therefore transported from sprocket 1 to sprocket 3, but it does not stop there and returns to sprocket 2 on which it meshes definitively.

Claims (2)

CLAIM Device for control by back-pedaling of gear changes with a single chain and multiple sprockets for bicycles, eliminating any kind of control transmission, characterized by the fact of using the chain itself to act directly by back-pedaling, on the usual sliding pinion, then actuated in the opposite direction to the normal direction, so that this pinion arms a mechanism producing, when returning to normal operation, the desired translation of said sliding pinion and thereby the movement of the chain of a pinion on another. SUB-CLAIMS 1 Device for controlling by back-pedaling and without any intermediate transmission device, single-chain and multi-sprocket gear changes, for bicycles according to claim, characterized in that the sliding pinion serves both as chain and carrier tensioner to make it jump from one sprocket and mesh with another sprocket, this sliding sprocket being integral with a sleeve rotating on ball bearings and around a ring arranged concentrically to a sleeve which is itself concentric with a fixed axis mounted by one of its ends on a support integral with the frame of the bicycle, the surface of this fixed axis. being notched with an endless helical path and a longitudinal rod and this sleeve being notched with an annular groove and cut out with a number of windows equal to that of the speeds, windows distributed in a determined manner over the circumference of the groove of the sleeve, the ring being split over part of its periphery to receive two parts hinged at a point on their surface on an axis passing through the thickness of this ring, a first curved part comprising at its free end a hook hook having a pointed beak curved inside the inner diameter of this ring, and having its other end subjected to the action of a spring tending to cause the angle of the hook to protrude on the periphery of the ring, and comprising, in addition, a protruding heel which fits into the annular groove of the sleeve, a second piece in the shape of a ratchet tooth, the heel of which is subjected to the action of a spring which constantly causes the tip of this tooth on the periphery of the band. 2 Device according to claim and sub-claim 1, as shown in the accompanying drawing.