Patent Application
20190368579
The present invention relates to a gear switching device, herein simply referred to as “transmission”, in particular, although without limitation, for human-powered vehicles.
According to a specific aspect, the invention relates to vehicles like bicycles, bike taxis, tricycles, quadcycles, torpedo bikes, urban rickshaws, tandems and the like.
Devices for gear switching in human-powered vehicles, such as bicycles, are well known; they comprise a plurality of pinions mounted coaxially with the hub of a drive wheel, each pinion having a different diameter so as to define a different gear ratio, a derailleur gear for disengaging the chain from a pinion and making it mesh with another pinion, so as to change gear, and a control, usually a cable manual control, for actuating the derailleur.
In these devices, the pinions are arranged on different planes, perpendicular to the hub of the drive wheel. This means that, in general, maximum one pinion is arranged on the same plane as the sprocket. Therefore, in general, the links of the transmission chain are not coplanar; contrariwise, they are arranged at an angle with respect to one another, wherein however the optimal operative condition for a transmission chain is that the links are aligned on the same plane. The arrangement described above causes significant friction between the links and causes therefore a loss of transmission power, that is greater or smaller in the various gears, as well as noise and wear, with loss of transverse rigidity, which requires frequent maintenance operations and jeopardizes the transmission functionality.
Another drawback of the derailleur gear systems is that it is impossible to switch quickly and/or directly from a gear to another, non-consecutive gear. This is disadvantageous in terms of vehicle performances, above all in case of sudden and steep slopes along the road.
Moreover, the derailleur systems does not allow to change gear when the vehicle is still, nor to start a climb having already selected the right gear.
To solve the problems mentioned above gear switching devices have been developed constituted by a cassette containing the gears, integrated in the hub of the drive wheel, that is typically the rear wheel, or in the central shaft. These devices comprise a plurality of toothed gears, each of which corresponds to a given gear ratio; all the toothed gears are arranged along an own axis, therefore they have a shape particularly elongated according to the direction of the axis. These devices have however numerous drawbacks.
The devices integrated in the hub-wheel are not suitable for retrofit, i.e. they cannot be mounted in existing vehicles, in particular for renewing vehicles based on old techniques. In fact, in these vehicles it is necessary to replace the existing wheel, where the devices shall be installed, with a suitable wheel, or to modify it, which is very difficult for a user to do. Moreover, the new hub with the integrated transmission replaces the normal hub and becomes part of the wheel; therefore, in case of damages to the wheel, the fast recovery of wheel and transmission is possible only having available a second wheel provided with transmission, and this significantly increases the related costs.
Moreover, the whole weight of the devices integrated in the hub-wheel is loaded on the rear wheel, thus reducing the vehicle dynamic balance.
On the other hand, for installing the devices integrated in the central shaft a specifically designed frame is required; for this reason, these devices can be replaced only with identical devices, thus limiting the user's freedom of choice. And, for the same reason, these devices do not allow retrofit.
Moreover, both with the devices integrated in the hub-wheel and with those integrated in the central shaft, of the type mentioned above, it is disadvantageous and even impossible to install a motor for a pedal-assisted vehicle, above all due to the axial bulk of the transmission devices, due to the arrangement along the axis of the toothed gears corresponding to the different gear ratios.
In fact, the known transmission devices to be installed in the hub of the drive wheel completely occupy the space that is usually used to install the motor, and it is therefore necessary to use a less common and more expensive motor that can be installed on the central axis or on the other wheel, typically the front wheel. On the other hand, the devices integrated in the central axis do not allow the integration with a coaxial motor as the resulting integrated device would be too long for being arranged between the pedals. For this reason, the motor shall be installed in correspondence of the hub of the drive wheel, typically the rear wheel, with analogous problems in terms of weight and loads distribution on the vehicle, problems that are even worsened in case the electric battery is mounted above the drive wheel.
U.S. Pat. No. 3,727,484 discloses a transmission for bicycles configured to be installed on the bottom bracket of a bicycle. The transmission comprises a multiple epicyclical gear train, comprising three concentric sun gears keyed on the shaft or pin of the cranks, three series of satellite gears and three outer gears or sprockets. These components substantially form three distinct epicyclical gear trains. The gear ratio is modified by selecting any one of the three epicyclical gear trains. This transmission is particularly complex and bulky. In fact, the need for arranging three epicyclical gear trains on an axis means a significant axial bulk. Moreover, if you want to increase the number of gear ratios, it is necessary to increase the number of epicyclical gear trains, and this in turns increases the axial bulk of the transmission device.
WO2011/142562 discloses a fixed-ratio epicyclical gear train, mounted on the spindle of a bottom bracket of the bicycle to have a better acceleration. This device does not allow gear switching.
DE 740086 discloses a transmission for vehicles, comprising a plurality of coaxial toothed gears keyed on a common shaft and a plurality of auxiliary shafts parallel to the common shaft, on which two auxiliary toothed gears are keyed. This transmission device is bulky and not suitable to be used on human-powered vehicles.
There is therefore a need for a transmission, especially although not exclusively for human-powered vehicles, that completely or partially, overcomes at least one of the drawbacks of the transmissions of the background art.
The object of some embodiments of the embodiments disclosed herein is to provide a human-powered vehicle equipped with a transmission system allowing to keep the transmission chain or belt aligned with a plane, independently of the selected gear ratio, and also allowing to switch quickly and/or directly from a gear ratio to another non-consecutive gear ratio, in particular allowing direct switching between the highest and the lowest gear ratio, and to pre-select the desired gear ratio before starting riding, in particular to pre-select a gear suitable for climbing.
A particular object of some embodiments is to provide such a transmission device, which is easy to install, in particular that can be easily installed on an existing vehicle, i.e. that is suitable for retrofitting.
A further object of some embodiments is to provide a transmission device having reduced dimensions compared to the prior art devices, in particular such as to facilitate the installation of a motor for pedal-assisted vehicles.
A further object of some embodiments is to provide a transmission device that has a limited weight compared to the prior art devices.
Another object of some embodiments is to provide such a vehicle, typically a pedal-assisted vehicle, for instance with an electric motor, that allows to load the weight of the transmission and of the motor mainly on the central part of the vehicle.
A further object of some embodiments is to provide an assisted pedal vehicle that allows to mount a motor, for example an electric motor, integrated in a single casing in the space between the pedal cranks, wherein the transmission device and the motor are coaxial with each other.
According to an aspect, to solve or overcome, at least partially, the drawbacks of the prior art transmission devices described above, a transmission device is provided, here below referred to simply as “transmission”, that comprises a support where an input central shaft is rotatably supported. The transmission also comprises a central wheel, connected to the central shaft and rotating therewith, and an output wheel. A rotary unit is also provided, rotatably supported by the support around a rotation axis thereof to take a plurality of angular positions. A plurality of selectable gear pairs are arranged on the rotary unit, each pair being rotatably mounted on the rotary unit. A rotation mechanism of the rotary unit is configured to bring the rotary unit into one of the angular positions, selectively. In each angular position of the rotary unit the respective selectable gear pair transmits motion from the central wheel to the output wheel. Each selectable gear pair is configured to provide a different gear ratio between the central wheel and the output wheel.
Each selectable gear pair gives a gear ratio. Having a rotary unit of sufficient dimension it is possible to have an even high number of selectable gear pairs without however increasing the axial bulk of the transmission device. Moreover, as it will be clearly apparent from the detailed description of embodiments, if the transmission is installed on a bicycle or on other human-powered vehicle using a continuous flexible member, such as a chain or a belt, for transmitting motion to the drive wheel, the switching of the gear does not entails a change in the lying plane of the continuous flexible member.
According to some embodiments of the invention, it is possible to change the gear ratio also when the vehicle is still. It is also possible to switch from any gear ratio to any other, not necessarily to an immediately preceding or immediately following one; in this way it is possible to achieve a greater functionality of the transmission.
In advantageous embodiments, each selectable gear pair comprises a respective primary gear and a respective secondary gear. In advantageous embodiments, the ratio between the diameter of the primary gear and the diameter of the respective secondary gear differs between the selectable gear pairs, so as to define a different gear ratio for each selectable gear pair.
In some embodiments of the invention, in order to have a compact and mechanically reliable configuration the rotary unit comprises two parallel rings mounted perpendicularly to the central shaft. In this case, the selectable gear pairs may be arranged between the two rings, with the respective rotation axes perpendicular to the rings.
A different configuration is also possible, for example with only one ring; in this case the primary gear and the secondary gear of each selectable gear pair are arranged on opposite sides of the ring, or they are both arranged on one side in a cantilevered fashion.
In some embodiments, the rotation mechanism comprises a switching unit suitable selectively to perform a switching movement and to make the rotary unit angularly displace around the rotation axis thereof so as: to disengage a currently selected one of said selectable gear pair (i.e. a currently working gear pair) from a mechanical transmission between the central wheel and the output wheel; and to make a further selectable gear pair, different from the current selectable gear pair, engage the mechanical transmission between the central wheel and the output wheel.
In some embodiments, an actuator unit is provided for controlling the switching movement of the switching unit. The switching unit may comprise, for example, a switching wheel provided with a switching pin that axially projects from an eccentric position of said switching wheel and is suitable to engage the rotary unit. The rotary unit may be provided with a plurality of radial grooves, the number of which is equal to the number of selectable gear pairs and which are arranged around the rotation axis of the rotary unit uniformly angularly spaced from each other by a fraction of a 360° angle and which are suitable to engage the switching pin of the switching wheel; so that a rotation of the switching wheel makes the switching pin engage one of the radial grooves and, as the rotation continues up to a complete turn, the switching pin makes the rotary unit rotate by an angle equal to the round angle (360°) divided by the number of selectable gear pairs.
Further advantageous features and embodiments of the transmission will be set forth in the description below and in the attached claims, which form an integral part of the present description.
According to a further aspect, a human-powered vehicle is provided, for example, although without limitation a bicycle, wherein a transmission, of the type described above and better detailed below, is associated to the central movement.
The present disclosure specifically concerns also a human-powered vehicle comprising:
The human-powered vehicle may be any vehicle powered through pedals, such as bicycles, bike taxis, tricycles, quadcycles, torpedo bikes, urban rickshaws, tandems, even actuatable by means of handles.
The term “pedals” refers to pedals of the traditional type, and also to equivalent devices actuatable by a user with his/her arms, for example handles.
The transmission member may be a transmission chain, and in this case the rotatable output element and the drive element of the drive wheel form a conventional sprocket-pinion pair. In these cases, the transmission device according to the invention allows the chain to move constantly aligned, i.e. arranged on a same plane parallel to the frame, thus maximizing the transmission efficiency and minimizing the wear of the transmission member.
The transmission member may be also a belt, preferably a toothed belt, or a different belt, for instance a trapezoid belt, transmitting motion by friction on the output elements and the drive elements, that are, in this case, a pair of pulleys, in the first case toothed pulleys.
The transmission member may be also different than those mentioned above; in particular, the transmission may comprise a transmission shaft.
The contact areas between the device according to the invention and the remaining part of the vehicle are only the points where the support of the transmission device is fastened to the frame, in order to make the support integral with the frame, and the contact point between the output element, i.e. the sprocket or the equivalent pulley, and the transmission chain or belt. The central shaft is integrated with the device, and the other members that contact it, i.e. cranks and pedals, do not have any contact point with the vehicle. With this kind of structure, the installation on a new vehicle or on an existing vehicle requires no much more work than the simple replacement of the central shaft. This allows greatly to simplify the mounting operation of a new vehicle, thus reducing the necessary time and costs; the vehicle can even have a frame of traditional shape in the area of the central axis, suitable for the installation of a normal transmission system comprising one or more sprockets and pinions, and a chain therebetween. Also the installation on an existing vehicle is simpler, for example for replacing a traditional transmission system already mounted on the vehicle, as there is no need for modifying the vehicle.
Moreover, in the transmission structure, the gear ratios are selected by making the output element, in particular the pulley or the sprocket, engage directly or indirectly respective selectable gear pairs arranged around a central axis, therefore parallel to one another and limited between planes perpendicular to the axis. In this way it is possible to have a limited bulk of the transmission device compared to other devices of the prior art that allow keeping the chain or belt always parallel to itself. Also thanks to this feature the transmission device is suitable for being installed on vehicles without any restrictions as regards the shape of the frame and without the need for onerous or even impossible modifications thereof.
The limited axial bulk of the transmission device according to the invention also allows introducing a pedal assist motor, coaxial with and advantageously integrated with the transmission device, all arranged in the space comprised between the cranks of the human-powered vehicle. In this way it is possible to overcome the limits and the disadvantages the known transmission devices have as regards the installation of motors.
In fact, contrariwise to the prior art transmission devices to be installed both in the hub-wheel and on the central axis, with the present invention it is not necessary to arrange masses on the hub of the drive wheel. Moreover, the weight of an integrated transmission-motor device according to the invention is lower than the sum of the weight of a known transmission device for hub-wheel or central axis and the weight of a motor for central axis and hub wheel respectively. Briefly, the invention allows to have a vehicle that is provided with both a transmission device and a motor, and has a lower weight, distributed in a more balanced way with respect to the prior art devices.
In particular, the transmission device comprises:
In an embodiment, the rings may be fastened together by means of one or more stiffening longitudinal elements arranged to prevent the two rings from rotating with respect to each other around the axis of the rotary unit.
In an embodiment, the output wheel is external with respect to the rotary unit and meshes selectively with only one selectable gear pair, and the rotary unit is arranged eccentric with respect to the central wheel, so that only a selected one of said selectable gear pairs meshes with both the central wheel and the output wheel. In this way, each selectable gear pair engages the central wheel only when the corresponding gear is selected, and therefore only the selectable gear pair corresponding to the selected gear rotates, whilst the other pairs remain still. This allows limiting friction, thus increasing the efficiency and decreasing the noise produced by the device, as well as the wear thereof.
In a further embodiment, the output wheel is again external with respect to the rotary unit and selectively meshes with only one of the selectable gear pairs, and the rotary unit is arranged coaxial with respect to the central wheel so that all the selectable gear pairs simultaneously mesh with the central wheel. In this way a significant simplification of the construction is achieved.
In a further embodiment, the output wheel is concentric with the rotary unit, and the central wheel meshes with the selectable gear pairs through an intermediate gear, the output wheel, integral with the output rotatable element, being provided as an internal wheel with respect to the output rotatable element. In this way, the radial bulk of the device is contained within the outer circumference of the output element. This allows having a device of limited bulk, and above all with a symmetric profile distribution, what is useful in case of vehicles where the appearance and the look are very important.
In particular, the central wheel engages the selectable gear pairs through an intermediate gear comprising a first intermediate wheel that meshes with the central wheel and a second intermediate wheel that can mesh selectively with each selectable gear pair through the rotation mechanism.
Advantageously, the rotation mechanism comprises a switching unit configured selectively to perform a switching movement and to make the rotary unit angularly displace around the axis by an integer multiple of a fraction of an angle of 360° based on the number of selectable gear pairs, so as:
An actuator unit is provided to actuate the switching movement of the switching unit; the actuator unit can be manual, equipped with an actuation control, or servo-assisted, i.e. equipped with a servomotor, typically an electric motor, having control buttons, the actuation control or control buttons being preferably arranged on a handlebar of the human-powered vehicle.
Preferably,
In particular, the switching unit comprises a coupling toothed gear having a longitudinally incomplete coupling/decoupling tooth, and the actuator unit is configured to cause a translation of the coupling toothed gear, so that
In this way, the actuation of the actuation device, combined with the user pedaling, makes a first selectable gear pair disengage from the central wheel, where it is directly or indirectly engaged, and/or from an output unit comprising an output wheel and the output element, and makes a new selectable gear pair engage directly or indirectly the central wheel and/or the output unit, causing the change i.e. the switching of the gear. Moreover, it is possible to pass from a gear to any other, i.e. switching from a given gear to another gear, even if not consecutive. This allows to switch from one gear ratio to another in a simple way, without the rider requiring particular attention or stopping pedaling, such that an optimal gear ratio can be selected also in case of sudden change in the road slopes.
In particular, elastic return means for returning to the normal running position are associated with the coupling toothed gear so that, by actuating the actuator unit without retaining it, the coupling toothed gear and the switching wheel make only one turn up to a position where the longitudinally incomplete tooth disengages, and therefore the rotary unit rotates by only a fraction of a 360° angle, causing the switching from a given transmission ratio to a contiguous transmission ratio.
Advantageously, the switching unit comprises at least one blocking element integral therewith, and the rotary unit is provided with a plurality of peripheral recesses that are uniformly angularly spaced from each other by the fraction of an angle of 360° and are configured to engage the blocking elements, the blocking elements being suitable to disengage the peripheral recesses when the switching unit causes the rotation of the rotary unit.
Preferably, said at least one blocking element is integral with the switching wheel and is arranged at a given angular position with respect to the switching pin, and the peripheral recesses are angularly offset with respect to the peripheral grooves by an offset angle such that when the switching pin engages the radial groove controlling the rotary unit, during the rotation of the switching wheel, the blocking elements disengage the peripheral recesses of the rotary unit.
In particular, the peripheral recesses are provided in correspondence of an edge of at least one of the two rings, so as to facilitate the engagement with the blocking element.
The peripheral recesses are preferably provided in correspondence of an edge of each ring, in corresponding angular positions of the two rings. This is necessary especially when the two rings of the rotary unit are not constrained to each other through the longitudinal stiffening elements mentioned above but are only slightly constrained to each other through the selectable gear pairs and therefore, when they are subjected to respective tangential loads generated by the radial loads of the toothing of the working selectable gear pair, if kept in position through a single blocking element, they could make a give rotation around the common axis, i.e. around the axis of the rotary unit.
The manual actuator unit may comprise a cable, fastened
In an embodiment, the second end of the cable is torsionally constrained to the switching unit so that, when the switching unit angularly displaces the rotary unit, the cable is subjected to a torsion depending on the angular displacement.
A display device is also provided for displaying the current gear, wherein an index, connected to the first end, is provided to make a displacement depending on the torsion, so as to show a symbol indicating the current gear.
In this way, the traction cable and the whole actuator unit transfer the information on the performed gear ratio switching to the display device. This allows to use the same kinematic chain both to transmit the actuation movements of the transmission device, in a direction of the cable, and reliably to receive from the transmission device a confirmation of the actuation, in the opposite direction, exploiting at the best the mechanical transmission properties of the cable and limiting the complexity of the device with respect to a return system separated from the actuator unit.
In some embodiments, the transmission device comprises an auxiliary pedal assisting motor. In some embodiments, the auxiliary motor comprises a rotor integral with the central wheel and a stator integral with the support, so as to transmit a rotary motion to the central wheel, also as a factor of sum of the motion imparted to the device by the user through the central shaft. In this way it is possible to have a modality of torque supply—on, off, modulation—that can be adapted to the specific local regulations, as the overall torque can be provided as the sum of the torque transmitted by the user through the pedals and the torque generated by the motor, or only as the torque generated by the motor, notwithstanding the possibility for the rider of actuating the vehicle through the pedals in a completely autonomous way.
The vehicle may comprise:
In particular, the rotor comprises permanent magnets integral with the central wheel, and the stator comprises electrical windings integral with the support.
The invention will be explained below by means of the description of some embodiments thereof, given just by way of non-limiting examples, and with reference to the attached drawing, where:
With reference to
Even if the description below is made only with reference to a bicycle 9, it is understood that it also applies, obviously with the necessary modifications, to any human-powered vehicle actuated through pedals or handles, such as bike taxis, tricycles, quadcycles, torpedo bikes, urban rickshaws, tandems.
Moreover, without limiting the general scope of the disclosure, reference will be made in the description to the case where the transmission member 5 is a chain, and therefore the output and drive elements are respectively a sprocket 19 and a pinion 4. However, any other transmission member may be provided for transmitting motion from the pedals to the wheel 6. In an embodiment, not shown, the transmission member 5 is a belt and the output and drive elements 4, 19 are pulleys, in particular a toothed belt mounted between toothed pulleys. In a further embodiment, not shown, the transmission member 5 comprises a drive shaft, for instance a cardan shaft.
Preferably, even if not mandatory, the support 40 is shaped like a box or casing, as shown in the figures.
Respective pedals 2 are mounted, through pedal cranks 2′, at the end of the shaft 1; through the pedals the shaft receives the rotary motion imparted by the user. According to the invention, the transmission device 7 is mounted between the central shaft 1 and the transmission chain 5. More precisely, the transmission device 7 is arranged between the frame 3 and one of the pedals 2, and has a drive shaft coinciding with the central shaft 1, while the output wheel or sprocket 19 meshes with the chain 5.
As shown in
As shown in
Advantageously, the rotary unit 100, seen from the side as in
In this case, the number n of selectable gear pairs is nine, corresponding to a same number of gear ratios between the central shaft 1 and the wheel 6 (
The central wheel 11 and the rotary unit 100 are arranged with the respective axes 1′ and 100′ parallel to each other, and spaced from each other by a distance E (
An integral guide, not shown, is arranged inside the casing 40 so as to allow a rotation of the rotary unit 100 with respect to the casing 40 and, therefore, with respect to the frame 3 (
Each selectable gear pair comprises a primary gear 111-119, and a secondary gear 121-129, parallel to one another, integral with an intermediate hub portion and spaced apart from one another by said intermediate hub portion so as to be adjacent to the rings 131 and 132 of the rotary unit 100 respectively. In particular, the primary gears 111-119, on the one hand, and the central wheel 11, on the other hand, are arranged so that the central wheel 11 can selectively engage each primary gear 111-119, transferring the rotation of the shaft 1 to the respective selectable gear pair 101-109 and making this rotary motion available through the respective secondary gear 121-129.
As shown in
With reference to
As shown in
By rotating the rotary unit 100 around the axis 100′ thereof, along the guide means integral with the support or casing 40, by the angle m 2π/n, where m is an integer comprised between 1 and n−1, a corresponding selectable gear pair 102-109, not necessary adjacent to the selectable gear pair 101, engages the central wheel 11 and the output wheel 18, respectively through the respective primary gear 112 or 119 and through the respective secondary wheel 122 or 129, thus setting the desired gear ratio.
To this end, as shown in
Advantageously, the switching wheel 71 is mounted just outside the rotary unit 100 and parallel to the ring 131. The switching wheel 71 advantageously has, in a peripheral portion thereof, a drawing member 72 that can be configured like a switching protuberance or pin 72 projecting towards the ring 131. Herein, the drawing member 72 will be referred to as “switching pin” 72.
In this case, as shown in
The coupling toothed gear 62 is advantageously provided with at least one coupling/decoupling tooth or incomplete tooth 64, i.e. a tooth realized in only one end portion along the height of the coupling toothed gear 62. Moreover, an auxiliary wheel or inversion wheel 68, meshing with the coupling toothed gear 62, is keyed to the secondary switching shaft 65.
The actuator unit may be a manual actuator unit 90, comprising a traction cable 91 as in
The manual actuator 90 is preferably actuatable through a control element 99 accessible by a user, such as a lever 99 arranged on the handlebar 8 of the vehicle (
In the embodiment of
Advantageously, the cursor 94 comprises an element 98 with increasing cross-section, for instance a truncated-conical element 98 coaxial with the remaining part of the cursor 94, beyond and preferably near the shoulder 94′.
The secondary switching shaft 65 is provided with a central hole along the axis 65′ thereof, where a slidable pin 79 is inserted, whose end 69 is kept pressed against the surface of the element with increasing cross-section 98 by means of an elastic return device 85, described below, resisting the translation of the slidable pin 79 moving away from the element 98. The opposite end 69′ of the slidable pin 79 rests on an arm of a lever 82, hinged at an intermediate point or pivot point to the casing 40, or to an element integral therewith; the opposite arm of the lever rests on the primary switching shaft 61, mounted slidable along the axis 61′ around a fixed pin 66, that is in turn mounted between two portions 41 and 42 integral with the casing 40. In this way, by pulling the cable 91, which results in the slidable pin 79 translating away from the element 98, the lever 82 controls a displacement of the primary switching shaft 61 in opposite direction.
An elastic element 85 is arranged between the coupling toothed gear 62 and the portion 41 of the casing, for example a further compression spring 85, preferably around a portion of the fixed pin 66, in order to form, together with the primary switching shaft 61 and the lever 82, said elastic return device, thanks to which, when there is no more traction through the cable 91, the slidable pin 79 returns to the position it had before the traction, translating in opposite direction with respect to what described above. In more detail, the coupling toothed gear 62 is keyed to the primary switching shaft 61 in such a position that, by applying a traction to the cable 91, the gear translates integrally with the primary switching shaft 61, making the coupling/decoupling incomplete tooth 64 thereof engage the central wheel 11. In this way, the rotary motion imparted by pedaling to the central wheel 11 is transmitted to the coupling toothed gear 62 and to the primary switching shaft 61 and also, through the auxiliary wheel 68, to the secondary switching shaft 65, in opposite direction of rotation. Therefore, also the switching wheel 71, which is keyed to the secondary switching shaft 65, is driven into rotation around the axis 65′, and the switching pin 72 makes a revolution around the axis 65′. The rotation of the primary and secondary shafts 61 and 65 continues until the coupling/decoupling tooth 64 meets again the central wheel 11, i.e. it continues for a complete turn of the coupling toothed gear 62; then, this latter disengages from the central wheel 11 and stops. If, on the contrary, the user continuously pulls the cable 91 for a prolonged time beyond the duration of one turn of the coupling toothed gear 62, and therefore of the secondary gear 68, the coupling toothed gear 62 continues rotating until the coupling/decoupling tooth 64 meets the central wheel 11 for the first time after that the user has released the control element 99.
During this rotation, the switching pin 72 moves progressively towards an edge of the disc 131 of the rotary unit 100, and engages inside one of the control grooves 150 provided radially in the disc 131, making the rotary unit 100 rotate by at least the angle 2π/n, or more in general a multiple m 2π/n of said angle. The switching pin 72 and the control groove 150 are configured so that the pin disengages the groove, thus causing the rotary unit 100 to stop rotating around the axis 100′, when a selectable gear pair 102 or 109, adjacent to the selectable gear pair 101, that before engaged the central wheel 11, has engaged the central wheel 11. In this way a new gear ratio is set.
The sequence of
However, if the action on the lever 99 continues beyond the duration of one turn of the coupling gear 62, this latter continues to rotate getting through one or more intermediate gear ratios, and making a selectable gear pair 101-108 mesh with the central wheel 11 immediately after the release of the lever 99 corresponding to a gear ratio which is not adjacent to the initial one.
In the gear ratio switching step, the rotary unit 100 is driven into rotation by the central shaft 1 through the central wheel 11, the coupling gear 62, the auxiliary wheel 68 and the switching wheel 71, due to the effect of pedaling. If pedaling is such that the central shaft 1 rotates clockwise, as shown in
The device 10 preferably comprises blocking means 76,160 for preventing the rotary unit 100 from rotating with respect to the support 40 during the normal running of the vehicle 9, and anyway outside the gear ratio switching steps. In the embodiment of
In particular, for the embodiment described above,
The blocking means preferably comprise two blocking elements 76 keyed at a reciprocal distance equal to the distance between the rings 131,132, and the peripheral recesses 160 are provided along the edge, in this case the inner edge, of both the rings 131,132, preferably as pairs of longitudinally aligned recesses.
This arrangement of the blocking recesses 160 and of the control grooves 150 is also shown in
In particular, the blocking element may comprise a half wheel 76 arranged so that the profile thereof is concentric with the switching wheel 71 and that, during the gear ratio switching step, the blocking element(s) 76 disengage the blocking recesses 160 corresponding to a current selectable gear pair immediately before, or exactly when, the switching pin 72 engages/disengages the radial control groove 150, so as to enable the rotation of the rotary unit 100 with respect to the casing 40.
To this end, in an embodiment of the invention the blocking element(s) 76 of each gear can be arranged in a position diametrically opposite to the switching pin 72.
The device 10 is preferably provided with communication means for indicating the currently selected gear ratio to the rider of the vehicle 9. In the embodiment illustrated in
In more detail, the communication means employ a degree of torsional freedom of the cable 91 not used for actuating the switching unit 70. To this end, in addition to the auxiliary gear 68 and the switching gear 71 also a primary communication wheel 86 is keyed to the secondary switching shaft 65, while a secondary communication wheel 87 is integrally provided on a portion of the actuator 90 torsionally integral with the cursor 94 and with the cable 91. In particular, the secondary communication wheel 87 is provided peripherally with respect to the bush 95 where the cursor 94 can slide but cannot rotate. In this way, while the switching unit 70 rotates, i.e. during a step of gear ratio switching, also the primary communication wheel 86 makes a complete turn, and makes the secondary communication wheel 87 rotate by a given angle, causing an equal rotation of the cursor 94 and a rotation/torsion of the cable 91 (
At the display device 200, the end of the cable 91 is inserted and blocked inside a cable gland gear 92 that therefore rotates integrally with the cable 91 during the gear ratio switching step (
Referring to
As shown in
The manual actuator unit 90 of the device 20 comprises the same components of the corresponding actuator unit of the device 10 (
Referring again to
The electric actuation motor 191 is configured so as to make the output shaft 193 rotate by angles equal to angle 2πz2/z1 (where z1 is the number of teeth of the primary actuation gear 186, and z2 is the number of teeth of the secondary actuation gear 187), or to an integer multiple thereof, so as to cause, through the first and the second actuation wheels 186, 187 corresponding complete rotations and revolutions of respectively the switching wheel 71 and the switching pin 72 around the axis 61′, so as to make the rotary unit 100 rotate around the axis 100′ coinciding with the axis of the central shaft 1′, by an angle corresponding to the angular distance between a selectable gear pair 101 currently meshing with the output wheel 18 and another selectable gear pair from 102 to 109 corresponding to a desired gear ratio, in particular a selectable gear pair 102 or 109 that is adjacent to the currently selected selectable gear pair 101, thus switching to the new gear ratio, according to what described above with reference to the first variant of the device 20 (
In this case it is not necessary to provide mechanical means for indicating the current gear ratio, as the servo-assisted actuator unit 190 may be provided with a rotation counter, for example an encoder, not shown, and with program means configured to receive a signal from the rotation counter and to transfer to a display device 200 the new selected gear ratio, after every actuation of the actuator unit 190.
Similarly, a variant of the device 10 according to the first embodiment (
The motor 300 further comprises a rotor 36, in this case provided with permanent magnets 37, integral with the central wheel 11. The set formed by the central wheel 11 and the rotor 36 is connected to the central shaft 1 through a freewheel 39 and a bearing 38. The freewheel 39 is configured to transmit the rotary motion from the central shaft 1 to the central wheel 11 and therefore to the motor in only one rotation direction, in this case in the rotation direction resulting in the forward movement of the vehicle 9, only if the motion coming from the auxiliary electric motor 300 does not exceed, in torque and rotation speed, the motion imparted by the user coming from the central shaft 1. In other words the auxiliary motor 300 adds its drive action to that of the user until the motion coming from the central shaft 1 has a speed lower than the maximum speed of the motion coming from the auxiliary motor 300. Only if the rider pedals very slowly (or does not pedal, in case the local laws allows the motor operation also in this case), the auxiliary motor 300 makes the whole traction work of the vehicle. In this way the torque from the motor does not interfere with the free rotation of the central shaft 1, but acts only as an aid for said free rotation.
The freewheel 39 does not allow the rotation of the central wheel 11 in the direction opposite to the running direction of the vehicle 9, acting through the central shaft 1. To avoid the freewheel 39 preventing the device according to the invention from switching the gear ratio by reverse pedaling, i.e. by pedaling in a direction opposite to the running direction, a detector 57 may be provided for detecting the rotation direction of the central shaft 1, configured to generate a signal indicating the running direction. The control unit 50 is configured to receive the rotation direction signal through conventional electric connection means, for example through the power supply cable 33 of the motor 300. The control unit 50 is configured so as to enable, once detected the rotation direction signal, the rotation of the auxiliary motor 300 also in case of pedaling, and therefore of rotation of the central shaft 1, according to a direction opposite to the vehicle actuation direction, thus making the gear ratio switching always possible.
In an embodiment of the invention, the detector 57 for detecting the rotation direction comprises a disc 35 integrally keyed to the central shaft 1 and provided with peripheral windows or notches 56 that are angularly equidistant from each other, a pair of sensors 57′ and 57″ emitting a signal and integral with the support 40, a sensitive end of which is arranged close to the face of the disc 35, and that are adjacent to one another along to the circumferential direction of the disc 35, configured to emit signal “zero” or signal “one” and to change state when the windows 56 pass in front of them during the rotation of the disc 35. In this way, if the sensor 57′ is the first to change state, as shown in the sequence of
Apart from what illustrated above, the motion transmission during the normal running, as well as the gear ratio switching steps are performed according to what described above with reference to the first variant of the device 10.
With reference to
Alternatively or in combination, the device 7 of respectively
Similarly, as shown in
In a further embodiment, as schematically shown in
Referring to
As shown in
Moreover, the manual actuator 90 comprises the same components as the corresponding actuator unit 90 of the device 10 (
With reference again to
Moreover, as schematically shown in
As shown in
The above description of specific embodiments discloses the invention from a conceptual viewpoint, so that other people, using the known technique, can modify and/or adapt in various applications these specific embodiments without further researches and without departing from the concept of the invention, and therefore it is intended that such adaptations and modifications shall be considered as equivalent to the specific embodiments. Means and materials to embody the various described functions can be of various nature without however departing from the protective scope of the present invention. It should be understood that used expressions and terminology have only descriptive, and therefore non limiting, purpose.
| Number | Date | Country | Kind |
|---|---|---|---|
| 102016000118893 | Nov 2016 | IT | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2017/079935 | 11/21/2017 | WO | 00 |
