Continuously variable transmission for bicycles

Abstract

A continuously variable transmission (CVT) device for bicycles, arranged at the bottom bracket, in a sealed and lubricated enclosure, comprising: a first mechanism having a driving pulley with two movable flanges, mounted on the bottom bracket shaft, the spacing of which, controlled by a hydraulic cylinder, defines the ratio, and a driven pulley with two movable flanges, mounted on an intermediate shaft, the two pulleys being connected by a belt tensioned by the action of a spring; a second, similar mechanism, having a driving pulley mounted on the intermediate shaft and a driven pulley mounted on the bottom bracket shaft, connected by a belt; the driven pulley of the first stage and the driving pulley of the second stage are joined by a ball bearing slide; the same applies to the connection between the driven pulley of the second stage and the hub carrying the sprocket of the bottom bracket. Figure for the abbreviation: Fig. 1

Description

Title of the invention: Continuously variable transmission for bicycles. TECHNICAL FIELD OF THE INVENTION

[0001] The present invention relates to a bicycle equipped with a continuously variable ratio device arranged at the level of the crankset in place of the multiple sprocket associated with the rear wheel and possibly of a multi-toothed chainring arranged at the level of the crankset.

[0002] More specifically, the continuously variable ratio elementary device consists of a driving pulley and a driven pulley, with two flanges of variable spacing, connected by a belt. The complete device comprises two elementary devices in series. STATE OF THE ART

[0003] The traditional transmission of a bicycle is ensured by a system called a derailleur. On the axle of the rear wheel, there is a set of fixed sprockets of different sizes (or number of teeth). Shifting from one to the other is achieved by the manually operated derailleur.

[0004] This multi-sprocket is linked by a chain to a single or multiple chainring connected to the crankset. In the case of a multiple chainring, a second derailleur system allows selection via a second manual control.

[0005] The combination of the two systems makes it possible to obtain more than thirty different gear ratios. The combination of sprockets and chainrings results in some quasi-redundancies that are complicated to manage.

[0006] This redundancy is all the more difficult to manage because of the two separate manual controls, even if, by being arranged on the handlebar, they can be operated simultaneously.

[0007] Moreover, the multiplicity of reports requires the controls to be almost precise and perfectly adjusted.

[0008] On the other hand, the derailleur operates under poor conditions due to its lack of protection from the environment, and the chain due to a near-permanent and more or less significant misalignment of the sprockets and chainrings. PRESENTATION OF THE INVENTION

[0009] The present invention proposes to replace the two selection systems (rear wheel and crankset) with a continuously variable device, arranged at the level of the crankset, with a single manual control, and protected from the external environment.

[0010] To obtain a high gear ratio range, the device comprises two belt-driven variators, mounted in series and with common hydraulic control. DETAILED DESCRIPTION OF THE INVENTION

[0011] These features, objectives and advantages of the present invention will become apparent from the detailed description that follows and from the accompanying drawings given by way of non-limiting examples and on which:

[0012] [Fig. 1] is a longitudinal AA sectional view focused on the general description of the components. The device is shown in the short report.

[0013] [Fig.2] is a cross-sectional BB view showing the angular positioning of the continuously variable ratio device.

[0014] [Fig.3] is a second longitudinal AA sectional view focused on the description of the first continuously variable ratio device. The device is shown in the long ratio.

[0015] [Fig.4] is a third longitudinal AA sectional view focused on the description of the second device with a continuously variable ratio. The device is shown in the long ratio.

[0016] [Fig. 5] is a fourth longitudinal AA sectional view focused on describing the power transmission from the bottom bracket shaft to the chainring. The device is shown in the short ratio.

[0017] The continuously variable device 10 shown in [Fig.1] is arranged in a closed and sealed space 30, containing a lubricant, comprising an oblong-shaped housing 31 and two side covers 32,33 secured by a series of tie rods 34.

[0018] The sealing, with respect to the external environment, between the housing 30 and the side covers 32,33 is obtained by the presence of static O-rings 35.

[0019] The walls of the covers 32,33 are crossed by a shaft 21 of a crankset 20 and the wall 32 is also crossed by a hub 25 output of the movement and power.

[0020] The dynamic seals of the passages of the covers 32,33 are the seal 36 between the bottom bracket shaft 21 and the cover 33, the seal 37 between the hub 25 and the cover 32, the seal 38 between the hub 25 and the bottom bracket shaft 21 20.

[0021] The shaft 21 of the crankset 20 is supported by the flange 33 via the ball bearing 42 and on the opposite side by the hub 25 via a ball slide 121, itself carried by the cover 32 by the ball bearing 43.

[0022] The shaft 21 of the crankset 20 is driven by muscular force via arms 22 and 23, each carrying a pedal (not shown) at its end. They are positioned on the shaft 21 by cones 22a-21a and 23a-21a and held in place by screws 24.

[0023] The continuously variable device has the following main components: • a first assembly 60 consisting of a driving pulley, with two flanges of variable spacing and controlled by a hydraulic cylinder, carried and driven by the crankshaft 21, a second similar pulley carried by an intermediate shaft 50 on which it is free in rotation and axial positioning. The two pulleys are joined by a belt; • A second assembly 90 consisting of a driving pulley, with two flanges of variable spacing and controlled by a second hydraulic cylinder, driven by the driven pulley of the first assembly 60, free to rotate on the intermediate shaft 50 and axially supported on it, and a second similar driven pulley carried by the shaft 21 of the crankset 20 on which it is free to rotate and axially position. The two pulleys are joined by a belt; • A motion and power output through the hub 25, driven by the driven pulley of the second assembly 90 and carrying the toothed plate 26, the detailed descriptions of these assemblies are made using [Fig.3] and [Fig.4],

[0024] The continuously variable device 10 shown in [Fig. 2] is a cross-section in the BB plane of the second continuously variable assembly 90. This section shows the arrangement of the device 10, inclined with respect to the horizontal plane 11 for easy integration into the bicycle frame (not shown), and a comfortable distance from the ground.

[0025] This view shows the housing 31 with its oblong contour, the cover 32 and the regular distribution of the lugs 32a for receiving the tie rods 34.

[0026] The closed and sealed space 30 contains a suitable fluid, both for lubrication and traction for continuously variable devices.

[0027] Filling (volumetric) is carried out by the plug 39 and emptying by the plug 40. The latter carries a magnet 41 for retaining the ferrous filings released by the break-in, and wear during use.

[0028] The toothed plate 26 transmits muscular power to the rear wheel via, in the embodiment presented, a toothed belt 27 (or a chain with links).

[0029] Figure 3 shows the continuously variable device according to a section AA similar to that of Figure 1. The device is presented here in the long ratio and the description focuses on the first continuously variable ratio device 60.

[0030] The crankshaft 21 carries the drive pulley of the continuously variable ratio device 60 composed of two flanges 61,62.

[0031] The flange 61, driven in rotation by means of the splines 61a-21a, axially supported on the shoulder 21b, carries the second flange 62 and drives it in rotation by the splines 61b-62b. They are axially mobile relative to each other.

[0032] The intermediate shaft 50 is the support of the driven pulley composed of the carrier flange 64 and the carried flange 65. They are linked in rotation by the splines 64a-65a and are axially free with respect to each other.

[0033] The intermediate shaft 50 is supported and axially blocked by the covers 32 and 33. In addition, it is blocked in rotation relative to the cover 32 by the pin 51.

[0034] The flange 64 carried by the needle bearing 66 is free to rotate relative to the intermediate shaft 50.

[0035] A spring 67 pushes the flanges 64, 65 towards each other, against a belt 63, thus putting the belt under tension. It bears on one side against the flange 65 and on the other side against a washer 68 held in place by a ring 69 carried by the supporting flange 64.

[0036] The two flanges 64,65 and the pressure spring 66 form a free assembly axially positioned by the belt 63.

[0037] The flange 62 is subjected to an axial thrust, via a ball bearing 82, from the annular piston 81 belonging to the cylinder 80, comprising a hydraulic chamber 81a.

[0038] Depending on the quantity of oil in chamber 81a, the flange 62 moves closer (increasing the radius of action of the belt 63 and increasing the ratio) or further away (reducing the radius of action of the belt 63 and reducing the ratio) from the flange 61.

[0039] Simultaneously, the flanges 64,65 have an opposite movement and the pressure (due to the preload) of the spring 67 ensures the tension of the strands of the belt 63.

[0040] The body of the cylinder 83 is centered in the cover 33 and bears against it. It is prevented from rotating by the lug 83a through which the fluid supply conduit 83b passes to the hydraulic chamber 81a. Sealing is ensured by the static O-ring seal 84.

[0041] The seal between the cylinder body 83 and the piston 81 is ensured by the two hydraulic translation seals 85.

[0042] The piston is blocked from rotation by the pin 86 planted in the body of the cylinder 83.

[0043] The chamber 81a of the cylinder 80 is supplied with pressurized oil by a series of conduits. First, in the cover 33, the supply conduit 33a feeds the conduit 33b. The conduit 33b corresponds with the conduit 50a, which passes radially through the intermediate shaft 50. The conduit 50a, in turn, corresponds with the conduit 33c, which supplies the axial conduit 83b in the lug 83a and the body 83 of the cylinder 80.

[0044] The channels 33b, 50a and 33c are aligned by means of the orienting pin 51. The sealing of these connections is achieved by the two static seals 55.

[0045] The channel network is supplied by a mechanically controlled (not shown) emitter piston piloted by the cyclist.

[0046] Fig. 4 shows the continuously variable device 10 according to a section AA similar to that of Fig. 1. The device is presented in the long ratio and the description focuses on the second continuously variable ratio device 90.

[0047] The intermediate shaft 50 carries the driving pulley of the continuously variable ratio device 90 composed of two flanges: the carrier flange 91 and the carried flange 92. They are rotationally fixed by the splines 91a-92a. They are axially movable relative to each other.

[0048] The bearing flange 91 is free to rotate relative to the fixed intermediate shaft 50. It is supported by a needle bearing 96. It bears axially on the shoulder 50d. A needle bearing 57 is interposed between the flange 91 and the shoulder 50d.

[0049] The movement and power are received by the flange 91 of the flange 64 of the driven pulley of the first continuously variable device 60.

[0050] Since the flange 64 is axially mobile and the flange 91 is in permanent stop, therefore fixed, the transmission between these two flanges is made via a ball slide 97.

[0051] The shaft 21 of the crankset 20, is the support of the driven pulley composed of the carrier flange 94 and the carried flange 95. They are linked in rotation by the splines 94a-95a and are axially free with respect to each other.

[0052] The bearing flange 94 is free to rotate relative to the shaft 21, which rotates at a different speed. It is supported by a needle bearing 98.

[0053] A spring 99 pushes the flanges 94, 95 towards each other, against a belt 93, thus putting the belt under tension. The spring presses on the flange 95 on one side and on a washer 100 held in place by a ring 101 carried by the supporting flange 94 on the other.

[0054] The two flanges 94,95 and the pressure spring 99 form a free assembly axially positioned by the belt 93.

[0055] The flange 92 is subjected to an axial thrust, via a ball bearing 110, from the annular piston 112 belonging to the cylinder 111, comprising a hydraulic chamber 111a.

[0056] Depending on the quantity of oil in chamber 11la, the flange 92 moves closer (increasing the radius of action of the belt 93 and increasing the ratio) or further away (reducing the radius of action of the belt 93 and reducing the ratio) from the flange 91.

[0057] Simultaneously, the flanges 94,95 have an opposite movement and the pressure of the spring 99 ensures the tension of the strands of the belt 93.

[0058] The body of the cylinder 111 is centered on the intermediate shaft 50 and bears against the cover 32. It is blocked from rotation by the pin 51. The piston is blocked from rotation by the pin 86 planted in the body of the cylinder 111.

[0059] The seal between the cylinder body 111 and the piston 112 is ensured by the two hydraulic translation seals 85.

[0060] The chamber 11a of the cylinder 111 is supplied with pressurized oil by a series of conduits. First, in the cover 33, the supply conduit 33a feeds the conduit 33b. The conduit 33b corresponds to the conduit 50a, which passes radially through the intermediate shaft 50. The conduit 50a, in turn, corresponds to the axial conduit 50b, which, at the other end of the intermediate shaft 50, supplies the radial conduit 50c. The latter, extending into the cylinder body, supplies a first conduit 111b and finally a second perpendicular conduit 111c, which until then forms the annular hydraulic chamber 111a.

[0061] The channels 33b, 50a on the one hand and 50c, 111b on the other are connected by means of the orienting pin 51. The sealing of these connections is achieved by the two static seals 55.

[0062] The channel network is supplied by a mechanically controlled piston emitter (not shown) common to the supply of the network of the first continuously variable device 60 and controlled by the cyclist.

[0063] The movement and power reaching the driven pulley of the second device 90 are transmitted to the hub 25.

[0064] Since the flange 94 is axially movable, while the hub 25 is fixed, the transmission between these two elements is achieved via a ball bearing slide 121, the inner ring 122 of which is driven by the splines 94a-95a, and the outer ring is the hub 25 itself. The inner ring 122 is axially retained by the washer 123 and the retaining ring 124. The hub 25 carries and drives the gear 26.

[0065] [Fig-5] shows the continuously variable device 10 according to an identical section AA to that of [Fig.1]. The device is presented on the short report and the description is focused on the transmission of power in the complete device.

[0066] The muscular force is supplied to the continuously variable device 10 by the arms 22,23 of the pedal 20. It is represented by the arrowed line 200.

[0067] Muscular force is transmitted: • at the shaft 21 of the crankset 20, it is represented by the arrowed line 201; • then to the driving pulley of the first continuously variable device 60, more precisely to the flange 61 driven by the shaft 21 by the splines 61a-21a, it is represented by the arrowed line 202; • then from the drive pulley of the first variable device 60 to the belt 63, it is represented by the arrowed line 203; • then by the belt 63 to the driven pulley, it is represented by the arrowed line 204; • then from the belt 63 to the flange 64 of the driven pulley, it is represented by the arrowed line 205; • then from flange 64 to inner ring of ball slide 97, it is represented by the arrowed line 206; • then from the inner ring to the outer ring of the ball slide 97, it is represented by the arrowed line 207; • then from the outer ring of the ball slide 97 to the flange 91 of the driven pulley of the second device 90, it is represented by the arrowed line 208; • then from the drive pulley of the second variable device 90 to the belt 93, it is represented by the arrowed line 209; • then by the belt 93 towards the driven pulley, it is represented by the arrowed line 210; • then from the belt 93 to the flange 94 of the driven pulley, it is represented by the arrowed line 211; • then from the flange 94, via the grooves 94a-95a, to the inner ring 122 of the ball slide 121, it is represented by the arrowed line 212; • then from the inner ring 122 to the outer ring (or hub) 25 of the ball slide 121, it is represented by the arrowed line 213; • and finally from the hub 25 to the gear 26, it is represented by the arrowed line 214.

Claims

Demands

1. A continuously variable device (10) for a bicycle, arranged at the level of the crankset (20) characterized by the following composition: • a closed and sealed space (30), containing a lubricant, is formed by an oblong-shaped housing (31), and two side covers (32,33) joined by a series of tie rods (34); • a shaft (21) of the pedal assembly (20) is driven by muscular force via the arms (22) and (23) each carrying at their end a pedal (not shown); • the walls of the covers (32,33) are crossed by the shaft (21) of the crankset (20) and the wall (32) is also crossed by a hub (25) for the output of the movement and power; • a mechanism whose main components are: • a first assembly (60) consisting of a driving pulley, with two flanges with variable spacing and controlled, carried and driven by the crankshaft (21), a second similar pulley carried by an intermediate shaft (50), the two pulleys are joined by a belt (63); • a second assembly (90) consisting of a driving pulley, with two flanges with variable spacing and piloted, driven by the driven pulley of the first assembly (60), and a second similar driven pulley carried by the shaft (21) of the crankset (20), the two pulleys are joined by a belt (93); • a motion and power output through a hub (25), driven by the driven pulley of the second assembly (90) and carrying a toothed plate (26).

2. Continuously variable device (10) for bicycle, according to claim 1 characterized in that in the first assembly (60): • the driving pulley is composed of two flanges (61,62); The flange (61), driven in rotation by means of the splines (61a-21a), bearing axially on a shoulder (21b), carries a second flange (62) and drives it in rotation by means of splines (61b-62b). They are axially mobile relative to each other; an intermediate shaft (50), is the support of a driven pulley composed of the carrier flange (64) and the carried flange (65), linked in rotation by splines (64a-65a) and axially free with respect to each other. the intermediate shaft (50) is carried and axially blocked by the side covers (32) and (33) and blocked in rotation relative to the cover (32) by a pin (51); the flange (64), carried by a needle bearing (66), is free to rotate relative to the intermediate shaft (50); a spring (67) pushes the flanges (64,65) towards each other, against a belt (63), and thus puts the latter under tension. It rests on the flange (65) on one side and on the other side on a washer (68) stopped by a ring (69) carried by the supporting flange (64); the two flanges (64,65) and the pressure spring (66) form a free assembly axially positioned by the belt (63); the flange (62) is subjected to an axial thrust, via a ball bearing (82), coming from the annular piston (81) belonging to the cylinder (80), comprising a hydraulic chamber 81a; depending on the amount of oil in chamber (81a): • either, the flange (62) moves closer to the flange (61) inducing an increase in the radius of action of the belt (63) on them and an increase in the ratio, because simultaneously the action of the belt (63) on the flanges (64,65) separates them (pressure on the spring (67)) and causes a decrease in the radius of action on them; • Either the flange (62) moves away from the flange (61), inducing a reduction in the radius of action of the belt (63) on them and a reduction in the ratio, because simultaneously the action of the belt (63) on

3. the flanges (64,65) bring them closer together (by the pressure of the spring (67)) and cause an increase in the radius of action on them; • The cylinder body (83) is centered in the cover (33) and rests against the latter. It is blocked from rotation by the lug (83a) through which passes the conduit (83b) supplying fluid to the hydraulic chamber (81a). Continuously variable device (10) for bicycle, according to claim 1 characterized in that in the second assembly (90): • the intermediate shaft (50), carries a driving pulley comprising two flanges: the carrier flange (91) and the carried flange (92), they are rotationally joined by the splines (91a-92a), they are axially movable relative to each other; • the carrier flange (91) is free to rotate relative to the fixed intermediate shaft (50), it is carried by a needle bearing bushing (96), it is axially supported on the shoulder (50d), a needle bearing stop (57) is interposed between the flange (91) and the shoulder (50c); • the movement and power are received by the flange (91) of the flange (64) of the driven pulley of the first continuously variable device (60); • the flange (64) being axially mobile and the flange (91) in permanent stop, therefore fixed, the transmission between these two flanges is made by means of a ball slide (97); • the shaft (21) of the crankset (20), is the support of the driven pulley composed of the bearing flange (94) and the supported flange (95). They are linked in rotation by the splines (94a-95a) and axially free with respect to each other; • the carrier flange (94) is free to rotate relative to the shaft (21) which rotates at a different speed. It is carried by a needle bearing (98); • a spring (99) pushes the flanges (94,95) towards each other, against a belt (93), and thus puts the latter under tension; the two flanges (94,95) and the pressure spring (99) form a free assembly axially positioned by the belt (93); the flange (92) is subjected to an axial thrust, via a ball bearing (110), coming from the annular piston (112) belonging to the cylinder (111), comprising a hydraulic chamber (111a); depending on the amount of oil in chamber (111a): • either, the flange (92) moves closer to the flange (91) inducing an increase in the radius of action of the belt (93) on them and an increase in the ratio, because simultaneously the action of the belt (93) on the flanges (94,95) separates them (pressure on the spring (99)) and causes a decrease in the radius of action on them; • Either the flange (92) moves away from the flange (91) inducing a reduction of the radius of action of the belt (93) on them and a reduction of the ratio, because simultaneously the action of the belt (93) on the flanges (94,95) brings them closer together (by the pressure of the spring (99)) and causes an increase in the radius of action on them; the cylinder body (111) is centered on the intermediate shaft (50) and rests on the cover (32), It is blocked from rotation by the pin (51); The movement and power reaching the driven pulley of the second device (90) are transmitted to the hub (25). The flange (94) being axially mobile, while the hub is fixed, the transmission between these two elements is made by means of a ball slide (121) whose inner ring (122) is driven by the splines (94a-95a) and the outer ring is the hub (25) itself, the hub (25) carries and drives the toothed wheel (26).

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