FR2797670A1 - Variable transmission for bicycle has wheel with fingers extending into two or more rings to be selectively engaged by transmission belt - Google Patents

Abstract

The variable transmission for a bicycle has a wheel (1) with fingers (5) extending in two or more rings (7-8) and slidable parallel to its axis between retracted and extended active positions. Levers (11,12) control the fingers for movement between the positions. A belt (2) has an inner face with projections co-operating with the fingers.

Description

The present invention relates to a speed-variable motion transmission device that can be used, for example, in human-powered vehicles such as bicycles, or in motor vehicles such as cars, motorcycles, trucks, etc.

There are many types of speed-varying motion transmission devices.

Of these, transmission gearboxes are widely used. A gearbox includes toothed gear gears mounted on separate parallel shafts to define one or more gear ratios by association of gears carried by different shafts. A disadvantage of such gearboxes lies in the fact that in order to modify the gear ratio used, it is necessary to disengage the engaged gears in order to mesh the gears corresponding to the desired gear ratio. In order not to damage the gears, the gearbox must be uncoupled from the motor shaft, for example by means of a clutch / disengagement device, so that the gear change is not carried out under charge. Such gearboxes are therefore expensive, both because of their relative difficulty of manufacture (precision of the parts and the adjustment thereof) than the necessary addition of a clutch / disengagement device.

Some so-called automatic gearboxes include a hydraulic torque converter associated with planetary planetary gear trains, some of whose elements are immobilized to obtain the desired gear ratios. Such transmissions allow gear ratios to change under load. However, these gearboxes are complex and relatively expensive. In addition, the hydraulic converters comprise quasi-permanent relative slip elements causing relatively large energy losses.

Also known are continuously variable transmission devices (or variators) comprising at least one pulley having two conical flanges between which a trapezoidal belt passes. The flanges are movable relative to each other so as to vary the radius of the arcuate zone of the flanges against which the belt is in contact. Such devices, however, do not allow transmission of high torque.

It is also known mechanical chain transmission devices comprising a stack of toothed gears of different diameters which is associated with a derailleur for moving the chain laterally from one pinion to another and thus to vary the gear ratio. gear. With these devices, it is difficult to change gear when the chain is subjected to a major effort. In addition, the lateral displacement of the chain causes energy losses by friction of the chain on the gears and causes wear chain and / or teeth of the gears.

An object of the invention is to provide a speed variation motion transmission device having a simple and reliable structure and allowing variation under load speed.

In order to achieve this, according to the invention, there is provided a device for transmitting motion with variation of speed, comprising - at least one wheel provided with fingers arranged in at least two rings centered on the axis of the wheel, the fingers of at least the outermost ring being mounted on the wheel to slide in a direction parallel to the axis thereof between an active position in which the fingers project from the wheel and an inactive position in which the fingers are recessed relative to their active position, - finger control means associated with at least the outermost ring to move the fingers this ring between their active and inactive positions, and - at least one flexible transmission member forming a loop and having a face facing the inside of the loop which has projections for cooperating with the fingers of one of the choice of said crowns.

Thus, each crown defines a gear ratio. The gear change is achieved either by successively retracting the fingers of the outer ring gear, the transmission member then being gradually brought into engagement with the immediately adjacent inner ring, or by bringing to their active position the fingers of a crown external immediately adjacent to the ring gear, the transmission member gradually engaging with the fingers of the outer ring as they come into their active position. The transmission member is gradually engaged with crowns during gear changes, which allows to obtain progressive and regular transition phases between gear ratios that can be made under a relative load. transmission member further remains aligned in the same plane and transmits the movement without energy loss due to parasitic friction.

According to a first particular embodiment, the control means comprise at least one cam in a circular arc extending facing a sector of the concerned crown in which the fingers are disengaged from the transmission member, said cam sliding between a first position in which the cam forms a ramp progressively moving the fingers of one of their active or inactive positions towards the other of their positions, and a second position in which said ramp is released from the free ends of the fingers. The fingers thus move progressively from their active position to their inactive position by the combination of the wheel rotation and the position of the cam which thus brings the fingers into the desired position during the rotational movement thanks to the support which it provides to the fingers. control means thus have a relatively simple structure.

Preferably, the device comprises a return pulley arranged to open the angle of said sector. The space that can be allocated to maneuvering fingers between their two positions is then increased.

Advantageously, the control means comprise two antagonistic cams mounted opposite one another on the same support to extend on each side of the wheel. The control of the fingers, both from their active position to their inactive position and from their inactive position to their active position, is in this way positively performed by the control means which retain a relatively simple structure.

According to a second particular embodiment, the control means are fluidic means. The fluid used can be an incompressible liquid (oil, water ...) or a gas (compressed air).

According to a third particular embodiment, the control means are. electromagnetic means which preferably comprises two conductive windings extending around each finger of the ring in question, the conductive windings being connected to terminals for being energized so as to form a finger activation winding and a winding of inactivation of the finger, the terminals advantageously opening outside the wheel to come rub on contacts in a circular arc connected a source of electrical power supply. The control means then a compact structure and allow an important speed of the control of the fingers.

According to a particular characteristic, the fingers of the innermost ring are fixed.

Advantageously, the fingers have enlarged ends forming abutment shoulders. The abutment shoulders limit the amplitude of the sliding of the fingers between their two positions and prevent them from being driven out of their housing during their sliding. In addition, abutment shoulders located on the side of the free end of the fingers when they are in the active position oppose accidental release of the transmission member in a direction parallel to the fingers.

According to another particular characteristic, the device comprises a plate secured to the wheel so as to extend facing it and provided with housings for receiving the free end portions of the fingers when they are in their active position, the plate being spaced from the wheel of an intermediate space sufficient to allow the passage between them of the transmission member. The fingers in their active position are then held by their two end portions, which increases their resistance to the force exerted via the transmission member. In addition, the plate provides a precise positioning of the transmission member relative to the wheel and fingers.

According to a particular embodiment of the transmission member, the transmission member is a mechanical chain, each link is curved and defines transversely a housing for a finger. chain allows the device of the invention to transmit movements under relatively large efforts.

According to two particular configurations of the transmission device, the retractable finger wheel is driving or the wheel is driven.

Other features and advantages of the invention will emerge on reading the following description of particular non-limiting embodiments of the invention.

1 is a partial view in elevation of a transmission device according to a first embodiment of the invention, FIG. 2 is a partial view of a transmission member of this invention. FIG. device, - Figures 3 to 7 are schematic perspective views illustrating in sequence the passage the transmission member of the outermost ring of fingers to the inner ring of fingers of the wheel of the transmission device of the figure 1, - Figure 8 is a diametrical sectional view of the wheel when the fingers of the outermost ring (the only ones represented) move from their inactive position to their active position, - Figure 9 is a diametrical sectional view of A wheel according to a second embodiment of the invention, - Figures 10 and 11 are partial views in diametral section of a wheel according to a third embodiment, for posi active and inactive fingers, - Figures 12 and 13 are schematic half-views in elevation of this wheel. With reference to FIGS. 1 to 8, the speed variation movement transmission device according to the invention comprises at least one driving wheel, not shown here, and a driven wheel generally designated in 1, connected to one another. other by a transmission member 2 closed on itself to form a loop.

The wheel 1 is integral with a not shown shaft which forms the output shaft of the transmission device and which is mounted on a frame itself not shown for pivoting about an axis 3 in a rotation direction referenced R in FIGS. .

The wheel 1 comprises two opposite faces 1.1, 1.2 substantially perpendicular to the axis 3, 1 transmission member 2 extending adjacent to the face 1.1 of the wheel 1.

The wheel 1 is traversed by bores 4 parallel to 1 axis 3 and arranged in a plurality (here three) of circles of different diameters centered on the axis 3.

The bores 4 receive cylindrical fingers 5 form an inner ring 6, an intermediate ring 7 and an outer ring 8. Each finger 5 has two opposite ends or enlarged heads 9.1, 9. forming shoulders 10.1, 10.2 opposite.

The fingers 5 of the inner ring 6 are fixed in the bores 4 so as to protrude from the face 1.1 of the wheel 1.

The fingers 5 of the intermediate and outer rings 7, 8 are mounted in the holes 4 to slide between active and inactive positions defined by the shoulders 10.2, 10.1 abutting respectively the faces 1.2 and 1.1 of the wheel 1. The fingers 5 s therefore protrude from the face <B> 1.1 </ B> of the wheel 1 when they are in the active position and are retracted with respect to this face when they are in the inactive position, only the widened ends 9.1 slightly exceeding of this face. The transmission device also comprises two generally designated control members 11, 12 associated respectively with the intermediate ring 7 and the outer ring 8.

Each control member 11, 12 comprises a stirrup 13, 14 on which are fixed vis-a-vis cam 15.1, 16.1 retraction of the corresponding ring 7, 8 relative to the face 1.1 of the wheel 1 which extends from side of the face 1.1 of the wheel 1 and a cam 15.2, 16.2 output of the corresponding ring 7, 8 relative to the face 1.1 which extends from the side of the face 1.2 of the wheel 1 (the output cam 15.2 is only partially visible in Figures 6 and 7 but has a structure similar to that of the output cam 16.2 which is clearly visible in Figures 4 to 8).

Each cam 15.1, 15.2, 16.1, 16.2 has a flat helicoidal section shape which is centered on the axis 3 and extends over an angle a facing a sector of the corresponding ring 7, 8. Each cam 15.1, 15.2, 16.1, 16.2 is arranged relative to the wheel 1 in such a way that the cam converges towards the face of the wheel 1 opposite which it extends in the direction of rotation R. Each cam 15.1, 15.2, ; 16.1, 16.2 is further disposed in a position such that the fingers 5 are always disengaged from the transmission member 2 when they arrive opposite said cam.

Each stirrup 13, 14 is mounted on the chassis of the transmission device to slide parallel to the axis 3 between a first position in which the corresponding output cam 15.2, 16.2 forms a ramp progressively moving the fingers 5 of the crown 7, 8 opposite their inactive position to their active position and the retraction cam 15.1, 16.1 corresponding is released free ends 9.1 of these fingers, and a second position in which the output cam 15.2, 16.2 concerned is disengaged from the free ends 9.2 fingers 5 of the corresponding ring 7, 8 and the retraction cam 15.1, 16.1 concerned form a ramp gradually moving these fingers from their active position to their inactive position.

The driving wheel is secured to the input shaft of the transmission device which is coupled to a rotating drive member such as a heat engine, an electric motor, a pedal ... The driving wheel is provided with a ring of fixed fingers projecting from one side of the wheel parallel to the axis of the drive shaft.

The transmission member 2 is here a mechanical chain comprising links 17 curved towards the outside of the loop to form an inner side thereof housing 18 for the fingers 5. The links are connected to each other articulated by axes 19. The transmission member can also be made from a toothed belt on its inner face to cooperate with the fingers 5.

The operation of the transmission device will now be described from a state of the transmission device, shown in FIG. 3, in which the fingers 5 of the intermediate and outer rings 8 and 7 are in their active position, the control members 11 and 12 being in their first position, the chain 2 meshing on the fingers 5 of the outer ring 8 to drive the wheel 1 in rotation about the axis 3 in the clockwise direction indicated by the arrow referenced R in FIGS. 3 to 7.

The modification of the gear ratio is carried out by bringing the control member 12 into its second position for sliding in the direction D. The retraction cam 16.1 is then brought closer to the face 1.1 of the wheel 1 and forms a bearing ramp of which the ends 9.1 of the fingers 5 of the outer ring 8 are brought successively so that these fingers are progressively moved to their inactive position, while the output cam 16.2 is released from the ends 9.2 of the fingers 5 of the outer ring 8 (FIG. 4).

As the rotation of the wheel and the retraction of the fingers 5 of the outer ring 8, the chain 2 gradually meshes with the fingers 5 of the intermediate ring 7 to finally be engaged only with this one (figure 5).

The transmission device may further comprise a return pulley, not shown, mounted on the frame of the transmission device, so as to open the angle formed by the upstream and downstream strands of the chain 2 on both sides of the transmission. 1. Advantageously, this pulley will be associated with an elastic member so as to form a chain tensioner to have a constant tension of the chain 2 regardless of the ring gear.

The operation of the transmission device will now be described from a state of the transmission device in which the fingers 5 of the intermediate ring 7 and outer 8 are in their active position, the control members 11 and 12 being in their first position. , the chain 2 meshing on the fingers 5 of the outer ring 8 to drive the wheel 1 in rotation about the axis 3 in the clockwise direction indicated by the arrow referenced R in FIGS. 3 to 7.

This state of the transmission device is shown in FIG.

A new modification of the gear ratio is achieved by bringing the control member 11 into its second position for sliding in the direction D. retraction cam 15.1 is then brought closer to the face 1.1 of the wheel 1 and forms a bearing ramp of which the ends 9.1 of the fingers 5 of the intermediate ring 7 are brought successively so that these fingers are progressively moved to their inactive position, while the output cam 15.2 is disengaged from the ends 9.2 fingers 5 of the intermediate ring 7 (FIG. ).

As the rotation of the wheel and the retraction of the intermediate ring fingers 7, the chain 2 gradually meshes with the fingers 5 of the inner ring 6 to finally be engaged only with that ci (Figure 7).

The elements that are identical or analogous to those previously described will bear the same numerical reference in the following description of the second and third embodiments of the invention.

The transmission device according to the second embodiment shown in Figure 9 comprises a plate 21 integral with the wheel 1 to extend facing the face 1.1 thereof. The plate 21 is spaced from the face 1.1 by a distance slightly greater than the width of the chain 2. The plate 21 is provided with housings 22 for receiving the free end portions 20.1 of the fingers 5 when they are in their position. active position.

In this embodiment, the fingers 5 comprise only one end or enlarged head 20.2.

The fingers 5 are received to slide in holes 4 of the wheel 1 which comprise a section 4.1 opening on the face 1.1 to receive the central portion of the fingers 5 and a section 4.2 having a section corresponding to that of the end 20.1 of the finger 5 so that the end 20 of the finger 5 seals the section 4.2 in two chambers. These chambers are connected by means not shown to a compressed air supply source itself not shown. You can also use a hydraulic power source. Thus, the control of the fingers between their active and inactive position is carried out by introducing air respectively into the chamber situated on the side of the face 1.2 of the wheel 1 or in the chamber located on the side of the face 1.1 thereof. .

Referring to Figures 10 to 13, the transmission device according to the third embodiment comprises a control member 23 of the fingers 5 of the outer ring 8 (here the only fingers shown in these figures) with, for each finger 5, a 24, a finger exit conductor winding and a finger retracting conductive winding 25, both of which extend around the finger in question.

Each conductive winding 24, 25 has ends connected to a ground terminal 26 (here common to both windings) opening on the face 1.2 of the wheel 1 and a terminal 27, 28 respectively opening on the face 1.1 of the wheel 1. The terminals 26, 27, 28 may also lead to the same face or around the wheel 1.

The control member 23 also comprises three contacts here in an arc - of which only two referenced 29 and 30 are shown in Figure 13 extending opposite the terminals 26, 27, 28 to rub on them. The contacts 29, 30 extend over the angle a facing a sector of the ring concerned, here 8, in a position such that the fingers 5 are disengaged from the transmission member 2 when they reach the level of these contacts as the wheel rotates 1.

The contacts 29, 30 are controllably connected to an electric power source not shown so that when the terminals 26 and 27 are connected to the power source by the corresponding contacts, the conductive winding 24 causes the corresponding, the conductive winding 24 causes the output of the finger in its active position protruding from the face 1.1 of the wheel 1 and that, when the terminals 26 and 28 are connected to the power source by the corresponding contacts, the conductive winding 25 causes the retraction of the finger in its inactive position.

The control member 23 is electrically isolated from the wheel 1. Wheel 1 can for this purpose be made of insulating material.

The control of the supply of the contacts 29, 30 is for example made electronically via a microprocessor.

Advantageously, there is provided a locking element of each finger 5 in its two positions here made in the form of a ball 31 retractable in a housing 32 of the wheel 1 and protruding from this housing by a spring 33 to be received in a groove 34 or a groove 35 formed in the finger 5 in correspondence of the finger positions.

Of course, the invention is not limited to the embodiment described and variants may be provided without departing from the scope of the invention as defined by the claims.

In particular, although the wheel 1 has been described as being driven, the wheel 1 can be driving. The transmission device according to the invention may further comprise a driving wheel and a driven wheel both equipped with movable fingers, or more than two wheels of this type.

Claims (8)

<U> CLAIMS </ U> 1. Device for transmitting speed variation movement, characterized in that it comprises - at least one wheel (1) provided with fingers arranged in at least two rings (6, 7, 8) centered on the (3) of the wheel, the fingers of at least the outermost ring (7, 8) being mounted on the wheel to slide in a direction parallel to the axis thereof between active position in which the fingers are projecting from the wheel (1) and an inactive position in which the fingers are set back from their active position, - finger control means (11, 12; 23) associated with at least the outermost ring (7, 8) to move the fingers of this ring between their inactive active positions, and at least one flexible transmission member (2) forming a loop and having a face facing the inside of the loop which has projections to cooperate with the fingers of the one at the choice of said crowns. 2. Transmission device according to claim 1, characterized in that the control means comprise at least one cam (15.1, 16.1, <B> 15.2, </ B> <B> 16.2) </ B> in an arc extending opposite a sector of the relevant ring (7, 8) in which the fingers (5) are disengaged from the transmission member (2), said cam sliding between a first position in which the cam forms a ramp progressively moving the fingers of one of their active or inactive positions to the other of their positions, and a second position in which said ramp is clear of the free ends of the fingers. 3. Transmission device according to claim 2, characterized in that it comprises a return pulley arranged to open 'angle said sector. 4 Transmission device according to claim 2 or claim 3, characterized in that the control means comprise two opposing cams (15.1, <B> 15.2 </ B>, 16.1, 16.2) mounted opposite one another on a same support (13, 14) for extending each side of the wheel (1). Transmission device according to Claim 1, characterized in that control means are fluidic means. Transmission device according to Claim 1, characterized in that control means are electromagnetic means (23). 7 Transmission device according to claim 6, characterized in that electromagnetic control means (23) comprise two conductive windings (24, 25) extending around each finger (5) of the respective ring 7, 8), the windings conductors being connected to terminals (26, 27, 28) to be energized to form a finger activation coil and a finger inactivation winding. 8. Transmission device according to claim 7, characterized in that the terminals (26, 27, 28) open out of the wheel (to come rub contacts in an arc (29, 30) connected to a source electric power supply device A transmission device according to any one of claims 1 to 8, characterized in that the fingers (5) of the innermost ring (6) are stationary 10. Transmission device according to any one of the preceding claims, characterized in that the fingers (5) have enlarged ends (9.1, 9) forming stop shoulders (10.1, 10. 11. Transmission device according to any one of the preceding claims, characterized in that it 'comprises a plate (21) integral with wheel (1) so as to extend facing it and provided with housings (22) for receiving the free end portions (20. fingers (5) when these are in their pos ition active, the plate (21) being spaced from the wheel (1) an intermediate space sufficient to allow passage between them of the transmission member (2). 12. Transmission device according to any one of the preceding claims, characterized in that the transmission member is a mechanical chain (2) each link (17) is curved transversely defines a housing (18) for a finger. 13. Transmission device according to any one of claims 1 to 12, characterized in that the wheel (1) is driving. 14. Transmission device according to any one of claims 1 to 12, characterized in that the wheel (1) is conducted.