Cardan-type transmission for vehicle

Abstract

The invention relates to a cardan-type transmission (200), comprising: - a first gear plate; - a second gear plate, and - a transmission shaft having a first gear wheel intended to engage with the first gear plate and a second gear wheel intended to engage with the second gear plate, wherein the second gear wheel comprises a hub and a plurality of teeth, characterised in that each tooth is movably mounted on the hub.

Description

Cardan type transmission for vehicle Field of invention

[0001] The field of the invention is that of the design and manufacture of vehicle equipment.

[0002] More particularly, the invention relates to a cardan-type transmission for a vehicle and a vehicle equipped with such a transmission. State of the art

[0003] To transmit a movement generated by motor means to a running gear, it is known to use transmission means.

[0004] The movement is commonly a torque provided by a motor to rotate at least one wheel of the vehicle.

[0005] The transmission means can be simple, that is to say that the torque received by the wheel is identical to that supplied by the motor, or almost, or at speed, allowing the torque received by the wheel to be increased or decreased compared to that supplied by the motor.

[0006] Among the different transmissions, the cardan type transmissions are known.

[0007] Such transmissions are used in particular on cycles, whether automotive (i.e. the engine is integrated into the vehicle) or so-called manual, i.e. the torque is generated by the user by means of an ad hoc interface, for example a pedal set.

[0008] On motorized cycles, for example motorcycles, transmissions are generally simple, with the change of torque ratio being handled by a gearbox inserted between the engine and the transmission.

[0009] On the other hand, on so-called manual cycles, for example bicycles, the transmissions can be geared.

[0010] This is for example the case of the transmission for a cycle described in the patent document published under number US2019 / 0300116. This transmission comprises:- a first crown intended to be coupled to the crankset;- a second crown intended to be coupled to a rear wheel of the cycle, and- a shaft carrying, at a first end, a first gear wheel intended to cooperate with the first crown and, at a second end, a second gear wheel intended to cooperate with the second crown.

[0011] The second crown has a plurality of concentric rings each intended to form a speed, and the second gear wheel is movable in translation along the shaft, via control means, to be positioned opposite a disk chosen according to the desired speed.

[0012] Although this transmission offers the advantage of a cardan shaft in the transmission of movement, the gear changes can only be carried out when the cycle is in motion;

[0013] In other words, it is not possible to change the transmission speed when the cyclist is stationary.

[0014] This then makes using the cycle difficult since the effort required by the cyclist to start the cycle can be significant.

[0015] Indeed, if the user stops in a configuration in which the second gear wheel cooperates with the largest ring of the second crown so as to limit the pedaling effort at a stabilized speed, he will have to start again in this same configuration. However, it is the cooperation of the second gear wheel with the smallest ring of the second crown which allows the user to provide the lowest effort.

[0016] Therefore, the user cannot restart with a low pedaling effort if he has not remembered to move the second gear wheel to the smallest ring before stopping.

[0017] The only solution for the cyclist is to get off his bike to raise the wheel coupled to the second crown and to manipulate the crankset by hand while controlling the gear change to position the second gear wheel opposite the second crown.

[0018] This is neither practical nor safe for the cyclist, especially when he is on a road also used by cars and trucks. Objectives of the invention

[0019] The invention aims in particular to overcome the drawbacks of the prior art.

[0020] More specifically, the invention aims to propose a cardan-type transmission allowing gear changes while stationary.

[0021] The invention also aims to provide such a transmission which is simple to operate.

[0022] The invention further aims to provide such a transmission which is reliable.

[0023] These objectives, as well as others which will appear subsequently, are achieved thanks to the invention which relates to a cardan type transmission comprising:- a first gear plate capable of being driven in rotation;- a second gear plate intended to be coupled to a wheel of a vehicle to allow the said wheel to be driven in rotation, and- a transmission shaft carrying, at a first end, a first gear wheel intended to cooperate with the first gear plate and, at a second end, a second gear wheel intended to cooperate with the second gear plate, in which the second gear plate has a plurality of concentric crowns each having a toothing formed by an alternation of crests and troughs, each crest of a crown being opposite a trough of an immediately adjacent crown, the crowns being each intended to form a transmission speed,in which the second gear wheel is movable in translation along the transmission shaft, via control means, to be positioned opposite a crown as a function of a desired speed, and in which the second gear wheel comprises a hub and a plurality of teeth extending radially projecting from the hub, characterized in that each tooth is mounted movably on the hub between a gear position in which the tooth projects from the hub when it is opposite a hollow of a crown, and a retracted position in which the tooth is at least partially retracted into the hub when it is located opposite a crest of a crown, and in that the hub comprises two discs separated by a spacer, each disc having a series of grooves, the grooves of the two discs being intended to be mounted opposite each other to form housings for receiving a tooth,each tooth comprising a pair of arms between which a wheel is rotatably mounted, and a rod intended to cooperate with a slot made in at least one of the hub discs, to guide the tooth in movement in its housing, the housings and the slots extending along a curved path relative to a radius of the hub discs.,

[0024] Such a transmission allows gear changes even when the vehicle is stationary, i.e. when the wheel to which the transmission is coupled is not moving.

[0025] This directly benefits the safety of the vehicle user who can remain on or in their vehicle to change gears while stationary.

[0026] Moreover, such a transmission is particularly reliable and robust.

[0027] Indeed, thanks to the mobility of the teeth between their retracted position and their gear position, gear changes have a limited, or even non-existent, impact on the teeth of the second gear wheel and on the second gear plate.

[0028] This is due to the fact that, by the position of the crests of a first crown opposite the hollows of the immediately adjacent crowns, the teeth of the second gear wheel pass into their retracted position so as not to hit the crests of the neighboring crowns during a gear change.

[0029] In other words, by shifting into their retracted position, the teeth of the second gear wheel do not hit the ridges of the crowns when changing gear.

[0030] This also improves user comfort.

[0031] The transmission architecture allows, thanks to the housings, to guide the teeth during their movements between the retracted position and the gear position.

[0032] Furthermore, in their retracted position, the teeth are held between the two discs, preventing them from twisting when in contact with the crowns. This therefore benefits the reliability of the transmission.

[0033] Finally, the use of discs allows the second gear wheel to be removed, in particular to replace weakened or worn teeth, for example.

[0034] The architecture of the teeth makes them robust while limiting their weight.

[0035] In fact, the use of a wheel between two arms makes it possible to limit the weight of the tooth which then has recesses allowing for clearance for the rotation of the wheel relative to the arms, compared to a machined or molded tooth.

[0036] The housings and slots extending in a curved path relative to a radius of the hub discs, this allows the rollers to be positioned relative to the recesses of the crowns in such a way that the cooperation of the teeth with the crowns does not risk causing the teeth to move towards their retracted position.

[0037] Furthermore, the curved trajectory allows for smooth movement of the teeth to limit their wear.

[0038] According to an advantageous aspect, the transmission also comprises means for moving the teeth into their retracted position from their gear position, and vice versa, the transmission means being formed by a first part and a second part.

[0039] The means of movement allow the mobility of the teeth between their gear position and their retracted position so as to limit shocks between the teeth and the crowns when changing gear, which benefits the life of the transmission.

[0040] Furthermore, limiting shocks helps limit the appearance of wear and tear which would harm the reliability and comfort of use of the transmission.

[0041] According to another advantageous aspect, the first part of the displacement means is in the form of a bevel made on the crests of the crowns and extending between an internal face and an external face of the crown, and / or a bevel made on the teeth of the second gear wheel, to cause the teeth to move from their gear position to their retracted position.

[0042] Bevels and / or chamfers allow for gentle movement of the teeth in contact with the crowns.

[0043] In other words, the inclined shape of the bevels and chamfers allows the teeth to slide on the crowns when the teeth come into contact with the crowns.

[0044] According to another advantageous aspect, the second part of the displacement means is in the form of at least one return member positioned between the hub and the teeth to cause the teeth to move from their retracted position to their gear position.

[0045] The presence of the return member makes it possible to push the teeth back into their gear position to facilitate the driving of the second gear plate by the second gear wheel.

[0046] Furthermore, when changing gears, the return member allows the teeth to be pushed back into the bottom of the ridges, which creates physical feedback that can be felt by the vehicle user, informing them that the gear change has been successful.

[0047] According to another advantageous aspect, the control means comprise a return element intended to push the second gear wheel in a first direction along the transmission shaft, and a cable actuable by a selector, and intended to exert a traction force against the return element in a second direction opposite to the first direction along the transmission shaft.

[0048] Such control means are simple to install and use.

[0049] Indeed, the balancing of the forces between the return element and the cable causes the second gear wheel to be held in position opposite a crown so as to allow cooperation between the teeth of the second gear wheel and the hollows of said crown.

[0050] The user then only has to manipulate the selector so that the movement of the second gear wheel is effective.

[0051] According to another advantageous aspect, the transmission comprises a casing inside which are mounted the transmission shaft, the first gear plate, the second gear plate, the first gear wheel and the second gear wheel, the casing being intended to be secured to a chassis of a vehicle.

[0052] The use of a casing allows, in addition to protecting the transmission elements, to facilitate the installation of the transmission on the chassis of a vehicle.

[0053] Indeed, through appropriate design, the casing can have standardized fixing points helping to position the transmission on a chassis.

[0054] The invention also relates to a vehicle comprising a transmission as previously described.

[0055] Such a vehicle offers increased comfort of use and reliability compared to vehicles equipped with transmissions according to the prior art. Figures

[0056] Other characteristics and advantages of the invention will appear more clearly on reading the following description of a preferred embodiment of the invention, given by way of illustrative and non-limiting example, and the appended drawings described below.

[0057] This is a partial schematic representation in perspective from above of a vehicle comprising a transmission according to the invention.

[0058] This is a partial schematic representation in perspective from above of a transmission according to the invention.

[0059] This is a schematic representation of a front part of the transmission according to the invention, comprising a first gear plate and a first gear wheel cooperating together.

[0060] This is a schematic representation of a rear part of the transmission according to the invention, comprising a second gear plate and a second gear wheel cooperating together.

[0061] This is a schematic perspective representation of the second gear plate, including an enlarged detail medallion.

[0062] This is a schematic perspective representation of the second gear wheel.

[0063] This is a partial schematic representation of the second gear wheel, according to insert V of the. Detailed description of the invention

[0064] Illustrates a vehicle 100 comprising a transmission 200 according to the invention.

[0065] More particularly, it illustrates only part of the vehicle 100, namely the chassis 110.

[0066] In this case, the vehicle 100 is a bicycle, and the chassis 110 is the frame of the bicycle.

[0067] With reference to Figures 2 to 7, the transmission 200 is now described.

[0068] As illustrated by Figures 2 and 3, the transmission 200 is of the cardan type and comprises:- a first gear plate 210;- a second gear plate 220, and- a transmission shaft 230 extending along an extension axis.

[0069] The first gear plate 210 is capable of being driven in rotation by means enabling the vehicle 100 to be set in motion. Such means take the form, for example, of a motor or, in this case, the pedal assembly of the bicycle.

[0070] The second gear plate 220 is intended to be coupled to a wheel of a vehicle 100 to enable the rotational drive of said wheel.

[0071] In this case, the second gear plate 220 is intended to be coupled to the rear wheel of the vehicle 100.

[0072] Each of the first gear plate 210 and the second gear plate 220 comprises at least one crown 240 having teeth formed by alternating crests 241 and valleys 242.

[0073] As will be described later, the second gear plate 220 has a plurality of concentric crowns 240, each crest 241 of a crown 240 facing a trough 242 of an immediately adjacent crown 240.

[0074] For the second gear plate 220, the crowns 240 are each intended to form a transmission speed.

[0075] In order to enable the transmission of movement between the first gear plate 210 and the second gear plate 220, and therefore the rotational drive of the wheel carrying the second gear plate 220, the transmission shaft 230 carries a first gear wheel 250 and a second gear wheel 260.

[0076] More specifically, the transmission shaft 230 carries, at a first end, the first gear wheel 250 which is intended to cooperate with the first gear plate 210 and, at a second end, the second gear wheel 260 which is intended to cooperate with the second gear plate 220.

[0077] With reference to the, the first gear wheel 250 comprises a central portion 251 from which a plurality of notches 252 protrude. The notches 252 are intended to be housed in the hollows 242 of the crown 240 of the first gear plate 210 to allow gearing between the first gear plate 210 and the first gear wheel 250.

[0078] Referring to Figures 6 and 7, the second gear wheel 260 comprises a hub 261 and a plurality of teeth 262 extending radially projecting from the hub 261. The teeth 262 are intended to be housed in the hollows 242 of the crowns 240 of the second gear plate 220 to allow gearing between the second gear plate 220 and the second gear wheel 260.

[0079] To enable the speed change, i.e. the cooperation of the second gear wheel 260 with the different crowns 240 of the second gear plate 220, the second gear wheel 260 is movable in translation along the transmission shaft 230. In other words, the second gear wheel 260 is movable in translation on the transmission shaft 230 along the extension axis.

[0080] In order to facilitate the translation of the second gear wheel 260 on the transmission shaft 230, the transmission shaft 230 has at least one notch 231 extending in a direction of extension of the transmission shaft 230, that is to say along the extension axis, and the second gear wheel 260 comprises at least one index 263 intended to cooperate with said at least one notch 231.

[0081] More specifically, as illustrated by the, the second gear wheel 260 comprises six indexes 263. The transmission shaft 230 then comprises six notches 231 each intended to cooperate with one of the indexes 263.

[0082] In any event, the transmission shaft 230 comprises as many notches 231 as the second gear wheel 260 comprises indexes 263, and vice versa.

[0083] The cooperation of the indexes 263 with the notches 231 then has the purpose of preventing the rotation of the second gear wheel 260 around the transmission shaft 230.

[0084] The movement of the second gear wheel 260 on the transmission shaft 230 is ensured by control means.

[0085] With reference to the, the control means comprise a return element 300 intended to push the second gear wheel 260 in a first direction along the transmission shaft 230, and a cable 400 coupled to the second gear wheel 260 and intended to exert a tensile force against the return element 300 in a second direction opposite to the first direction, to move the second gear wheel 260 along the transmission shaft 230.

[0086] Cable 400 can be operated by a selector not shown.

[0087] The return element 300 is for example a compression spring positioned between the second gear wheel 260 and a stop ring 500 fixedly mounted on the transmission shaft 230.

[0088] Alternatively, the return element 300 could be a tension spring or any other element providing a similar function.

[0089] The control means also comprise a finger 600 secured to the second gear wheel 260 and to which the cable 400 is attached.

[0090] During a gear change, the cable 400 acts on the finger 600 to allow the movement of the second gear wheel 260 in the first direction or in the second direction.

[0091] More specifically, when the speeds are increased, i.e. the second gear wheel 260 is moved in the second direction to cooperate with a larger diameter crown 240 of the second gear plate 220, the cable 400 exerts a tensile force on the finger 600 in the direction of the stop ring 500, so as to compress the return element 300.

[0092] Conversely, when the speeds are reduced, that is to say the second gear wheel 260 is moved in the first direction to cooperate with a crown 240 of smaller diameter of the second gear plate 220, the cable 400 releases the force that it exerts on the finger 600 so that the return element 300 relaxes to move the second gear wheel 260 away from the stop ring 500.

[0093] As previously described, the second gear wheel 260 comprises a hub 261 and a plurality of teeth 262 extending radially projecting from the hub 261. The teeth 262 are intended to be housed in the hollows 242 of the crowns 240 of the second gear plate 220 to allow meshing between the second gear plate 220 and the second gear wheel 260.

[0094] To allow a gear change when the vehicle 100 is stationary, each tooth 262 of the second gear wheel 260 is mounted movably on the hub 261 between a gear position in which the tooth 262 projects from the hub 261 when it is opposite a hollow 242 of a crown 240, and a retracted position in which the tooth 262 is at least partially retracted into the hub 261 when it is located opposite a crest 241 of a crown 240.

[0095] With reference to figures 6 and 7, the hub 261 comprises two discs 264 separated by a spacer 265, each disc having a series of grooves 266, the grooves 266 of the two discs being intended to be mounted opposite each other to form housings for receiving a tooth 262.

[0096] The teeth 262 are thus movable in the housings formed by the two discs 264.

[0097] Each tooth 262 comprises a pair of arms 267 between which a roller 268 is rotatably mounted.

[0098] Furthermore, each tooth 262 comprises a rod 269 intended to cooperate with a slot 2640 made in at least one of the discs 264 of the hub 261, to guide the tooth 262 in movement in its housing.

[0099] More specifically, for each housing, each disc 264 has a slot 2640 allowing the tooth 260 that it receives to be guided.

[0100] As illustrated by the, the housings and slots 2640 extend in a curved path relative to a radius of the discs 264 of the hub 261.

[0101] As will be explained below, this makes it possible to create a cooperative force of the teeth 262 with the crowns 240 which prevents the movement of the teeth 262 towards their retracted position during the rotational driving of the second gear plate 220 by the second gear wheel 260.

[0102] In order to ensure the movement of the teeth 262 between their retracted position and their gear position, the transmission 200 also comprises means for moving the teeth 262 into their retracted position from their gear position, and vice versa.

[0103] The transmission means are formed by a first part and a second part.

[0104] With reference to figures 5 to 7, the first part of the displacement means is in the form of a bevel 270 made on the crests 241 of the crowns 240 and extending between an internal face 243 and an external face 244 of the crown 240, and / or a bevel 280 made on the teeth 262 of the second gear wheel 260.

[0105] The bevels 270 form a junction between the internal face 243 and the external face 244 of each crown 240.

[0106] More specifically, with reference to the detail medallion of the, each crest 241 has a first portion substantially complementary in shape with the teeth 262 and a second portion on which the teeth 262 are intended to slide.

[0107] The bevel 270 is thus carried by the second portion of the ridge 241.

[0108] The sliding of the teeth on the second portion, that is to say on the bevel 270 then causes the movement of the teeth 262 towards their retracted position in order to allow a change of speed, but also to allow free rotation of the second gear plate 220 relative to the second gear wheel 260. The free rotation of the second gear plate 220 relative to the second gear wheel 260 causes a freewheeling phenomenon of the transmission 200.

[0109] The bevels 280 are made on the arms 267 at the level of the wheel 268 and continue with a chamfer 290 made on the wheel 268. The bevels 280 and chamfers 290 thus extend in the same plane.

[0110] The bevels 270, the bevels 280 and the chamfers 290 cause the teeth 262 to move from their gear position to their retracted position when the teeth 262 come into contact with a crown 240, that is to say during a gear change.

[0111] In order to ensure the transmission of torque between the second gear wheel 260 and the second gear plate 220, the second part of the displacement means is in the form of at least one return member 700 positioned between the hub 261 and the teeth 262 to cause the teeth 262 to move from their retracted position to their gear position.

[0112] More precisely, with reference to which it is represented schematically, the return member 700 takes the form of an elastically deformable ring, surrounding the spacer 265 of the hub 261.

[0113] The elastically deformable ring, i.e. the return member 700, tends to push the teeth 262 back into their gear position.

[0114] When the teeth 262 are pushed back towards their retracted position, by cooperation with a ridge 241 during a gear change or during freewheeling, the return member 700 deforms elastically under the pressure exerted by the teeth 262 to allow the teeth 262 to come into the retracted position.

[0115] When the teeth 262 are again opposite a hollow 242 of a crown 240, the return member 700 tends to recover its initial position and pushes the teeth 262 back into their gear position, which makes it possible to produce the gear between the second gear wheel 260 and the second gear plate 220.

[0116] The transmission also includes an 800 case.

[0117] The transmission shaft 230, the first gear plate 210, the second gear plate 220, the first gear wheel 250 and the second gear wheel 260 are then mounted in the casing 800 in order to be protected, in particular from external elements such as mud, dust, stones or even water.

[0118] In more detail, the casing 800 has: - a first enclosure 810 in which the first gear plate 210 and the first gear wheel 250 are located, - a second enclosure 820 in which the second gear plate 220, the second gear wheel 260, the stop ring 500, the return element 300 and the finger 600 are located, and - a tube 830 in which the transmission shaft 230 is placed.

[0119] The second enclosure 820 has an opening allowing the passage of the cable 400 to allow the control of the finger 600 and therefore the movement of the second gear wheel 260 along the transmission shaft 230.

[0120] The casing 800 is intended to be secured to the chassis 110 of the vehicle 100 by ad hoc means.

[0121] The 200 transmission which has just been described has many advantages over existing solutions, including: - no risk of derailment; - low wear thanks to the mobility of the teeth of the second gear wheel; - little soiling thanks to the presence of the casing; - ease of use; - possibility of changing gears when the vehicle is stopped; - easily scalable number of speeds by adding or removing crowns on the second gear plate and modifying the travel of the second gear wheel on the transmission shaft; - smooth and flexible change of speeds; - possibility of modifying the mechanical movement of the second gear wheel on the transmission shaft into an electronic movement, and - possibility of integrating the transmission into complex vehicle chassis (extended, shortened, foldable chassis, etc.).

Claims

A cardan-type transmission (200) comprising: - a first gear plate (210) capable of being driven in rotation; - a second gear plate (220) intended to be coupled to a wheel of a vehicle (100) to enable said wheel to be driven in rotation, and - a transmission shaft (230) carrying, at a first end, a first gear wheel (250) intended to cooperate with the first gear plate (210) and, at a second end, a second gear wheel (260) intended to cooperate with the second gear plate (220), in which the second gear plate (220) has a plurality of concentric crowns (240) each having a toothing formed by an alternation of crests (241) and hollows (242), each crest (241) of a crown (240) being opposite a hollow (242) of a crown (240) immediately adjacent, the crowns (240) being intended to each form a transmission speed,wherein the second gear wheel (260) is movable in translation along the transmission shaft (230), via control means, to be positioned opposite a crown (240) as a function of a desired speed, and wherein the second gear wheel (260) comprises a hub (261) and a plurality of teeth (262) extending radially projecting from the hub (261), characterized in that each tooth (262) is mounted movably on the hub (261) between a gear position in which the tooth (262) projects from the hub (261) when it is opposite a hollow (242) of a crown (240), and a retracted position in which the tooth (262) is at least partially retracted into the hub (261) when it is located opposite a crest (241) of a crown (240), and in that that the hub (261) comprises two discs (264) separated by a spacer (265), each disc (264) having a series of grooves (266),the grooves (266) of the two discs (264) being intended to be mounted opposite each other to form housings for receiving a tooth (262), each tooth (262) comprising a pair of arms (267) between which a roller (268) is rotatably mounted, and a rod (269) intended to cooperate with a slot (2640) made in at least one of the discs (264) of the hub (261), to guide the tooth (262) in movement in its housing, the housings and the slots (2640) extending along a curved path relative to a radius of the discs (264) of the hub (261)., Transmission (200) according to the preceding claim, characterized in that the transmission (200) also comprises means for moving the teeth (262) into their retracted position from their gear position, and vice versa, the transmission means being formed by a first part and a second part. Transmission (200) according to the preceding claim, characterized in that the first part of the displacement means is in the form of a bevel (270) made on the crests (of the crowns and extending between an internal face and an external face of the crown, and / or a beveling made on the teeth of the second gear wheel, to cause the teeth to move from their gear position to their retracted position. Transmission (200) according to claim 2, characterized in that the second part of the displacement means is in the form of at least one return member (700) positioned between the hub (261) and the teeth (262) to cause the teeth (262) to move from their retracted position to their gear position. Transmission (200) according to any one of the preceding claims, characterized in that the control means comprise a return element (300) intended to push the second gear wheel (260) in a first direction along the transmission shaft (230), and a cable (400) actuable by a selector, and intended to exert a traction force against the return element (300) in a second direction opposite to the first direction along the transmission shaft (230). Transmission (200) according to any one of the preceding claims, characterized in that it comprises a casing (800) inside which are mounted the transmission shaft (230), the first gear plate (210), the second gear plate (220), the first gear wheel (250) and the second gear wheel (260), the casing (800) being intended to be secured to a chassis (110) of a vehicle (100). A vehicle (100) comprising a transmission (200) according to any preceding claim.

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