阅读说明：本技术 用于自行车的带有前离合器的自由轮组件 (Freewheel assembly with front clutch for a bicycle ) 是由 恩里科·菲德尔法蒂 基斯·约瑟夫·韦克厄姆 于 2019-07-03 设计创作，主要内容包括：一种用于自行车的带有前离合器的自由轮组件(10),包括：轮毂套筒(11),其能够在轮毂销上旋转,和盒(25),该盒以可旋转的方式安装在轮毂销上；第一环形体(15),其能够在轮毂销上旋转并且包括第一冠状齿轮；第二环形体(16),其与轮毂套筒相关联并且包括面向第一冠状齿轮的匹配的第二冠状齿轮。第一环形体(15)能够相对于第二环形体(16)在传动构造和自由轮构造之间轴向移动,并且联接部件(28)在第一环形体和盒之间操作。当第一环形体为自由轮构造时,盒相对于第一环形体的旋转迫使联接部件(28)使第一环形体朝向第二环形体轴向平移,并且磁性部件(38)在第一环形体上起作用并且被构造成阻止第一环形体相对于轮毂销(13)的旋转。(Freewheel assembly (10) with front clutch for a bicycle, comprising: a hub sleeve (11) rotatable on the hub pin, and a cassette (25) rotatably mounted on the hub pin; a first ring body (15) rotatable on the hub pin and comprising a first crown gear; a second annular body (16) associated with the hub sleeve and comprising a matching second crown gear facing the first crown gear. The first annular body (15) is axially movable with respect to the second annular body (16) between a transmission configuration and a free-wheel configuration, and a coupling member (28) operates between the first annular body and the cassette. When the first annular body is in a free-wheel configuration, rotation of the cartridge relative to the first annular body forces the coupling member (28) to axially translate the first annular body towards the second annular body, and the magnetic member (38) acts on the first annular body and is configured to prevent rotation of the first annular body relative to the hub pin (13).)

1. Freewheel assembly (10) with front clutch for a bicycle, comprising:

a hub sleeve (11) rotatably mounted on a hub pin (13) about a rotation axis (X), and a cartridge (25) rotatably mounted on the hub pin (13);

a first annular body (15) which is rotatable about said rotation axis (X) in a first angular direction (A) and a second angular direction (B), is inserted in a rotatable manner on said hub pin (13), and comprises a first crown gear (17);

a second annular body (16) rotationally coupled with the hub sleeve (11) and comprising a second crown wheel (23) matching the first crown wheel (17) and axially facing the first crown wheel (17);

-said first annular body (15) is axially movable with respect to said second annular body (16) between a transmission configuration, in which said first crown wheel (17) is coupled with said second crown wheel (23), and a free-wheel configuration, in which said first crown wheel (17) is uncoupled from said second crown wheel (18) and said first annular body (15) does not transmit motion to said second annular body (16);

-a coupling member (28) operating between the first annular body (15) and the box (25);

wherein, when the first annular body (15) is in the free-wheel configuration, rotation of the box (25) with respect to the first annular body (15) forces the coupling member (28) to axially translate the first annular body (15) towards the second annular body (16),

and wherein a magnetic component (38) is configured to prevent rotation of the first annular body (15) relative to the hub pin (13).

2. Freewheel assembly (10) according to claim 1, wherein the magnetic part (38) acts between the hub pin (13) and the first annular body (15).

3. A freewheel assembly (10) according to claim 1, wherein the magnetic component (38) is configured to apply a resistance torque that prevents rotation of the first annular body (15) with respect to the hub pin (13), the resistance torque being smaller than a predetermined driving torque adapted to rotate the first annular body (15) with respect to the hub pin (13).

4. Freewheel assembly (10) according to claim 1, wherein the first annular body (15) has a predetermined axial dimension; when the first annular body (15) is in the free-wheel configuration, the magnetic component (38) acts on a portion of the first annular body (15) having an axial extension of at least 25% of the predetermined axial dimension.

5. Freewheel assembly (10) according to claim 1, wherein the coupling means (28) comprise a plurality of guides (37) extending in a volute or spiral shape, operating between the first annular body (15) and the box (25);

wherein the extension of the volute guide (37) in the axial direction is preferably greater than or equal to the axial distance between the first crown gear (17) and the second crown gear (23) when the first annular body (15) is in the free wheel configuration.

6. Freewheel assembly (10) according to claim 1, comprising holding magnets (44, 47), the holding magnets (44, 47) operating axially on the first annular body (15) to hold the first annular body (15) in the freewheel position.

7. Freewheel assembly (10) according to claim 1, wherein the magnetic part (38) comprises at least one portion made of ferromagnetic material (15a, 15b) of the annular body (15) and at least one permanent magnet (44).

8. Freewheel assembly (10) according to claim 7, wherein the part made of ferromagnetic material (15a, 15b) of the first annular body (15) is at least partly made of a steel alloy, or an iron-nickel-aluminum alloy, or an iron-silicon alloy, or an iron-nickel alloy, or a combination thereof.

9. Freewheel assembly (10) according to claim 1, wherein the magnetic part (38) comprises a magnetized body (39) fixedly connected to the hub pin (13), facing radially the radially inner part (15a) of the first annular body (15) and axially the axially outer part (15b) of the first annular body (15), so as to realize a magnetic circuit through the first annular body (15).

10. Freewheel assembly (10) according to claim 9, wherein the magnetized body (39) comprises a plurality of protrusions (43), the plurality of protrusions (43) pointing radially towards the first annular body (15), and

wherein the first annular body (15) comprises a plurality of protrusions (42), the plurality of protrusions (42) being radially directed towards the magnetized body (39); the radial distance between the projections (42) of the first annular body (15) and the projections (43) of the magnetizing body (39) defines a gap in the magnetic circuit.

11. Freewheel assembly (10) according to claim 10, wherein the projections (42) of the first plurality of projections (42) of the first annular body (15) have the same radial and circumferential extension and are circumferentially separated from each other by the same distance, and

wherein the protrusions (43) of the first plurality of protrusions (43) of the magnetized body (39) have the same radial and circumferential extension and are circumferentially separated from each other by the same distance.

12. Freewheel assembly (10) according to claim 7, comprising a holding magnet (44, 47), the holding magnet (44, 47) operating axially on the first annular body (15) to hold the first annular body (15) in the freewheel position, wherein the holding magnet (44) coincides with the permanent magnet (44) of the magnetic part (38).

13. Freewheel assembly (10) according to any of claims 1-6, wherein the magnetic component (38) comprises a first magnet (45) fixedly connected to the hub pin (13) and at least one second magnet (46) rotating as a unit with the first annular body (15) and magnetically interacting with the first magnet (45).

14. Freewheel assembly (10) according to claim 13, wherein the first magnet (45) and the at least one second magnet (46) have a radially directed polarization.

15. Freewheel assembly (10) according to claim 14, wherein a plurality of first magnets (45) follow each other and are spaced apart from each other in the circumferential direction; two circumferentially adjacent first magnets (45) are of opposite polarity.

Technical Field

The invention relates to a freewheel with a front clutch for a bicycle.

Background

A transmission system for a bicycle comprising: a pair of pedal cranks on which the rider exerts a propulsive thrust; one or more drive gears set in rotation by direct coupling with the pedal crank; and a plurality of driven gears (also referred to as sprockets) having different sizes, which are set to rotate by the driving gear through the transmission chain.

The sprocket is coupled to the rear wheel of the bicycle through a box that is rotatably coupled to the hub sleeve. The hub sleeve rotates as a unit with the rim of the bicycle through the spokes and is rotatably fitted onto a hub pin fixed relative to the frame of the bicycle. The cassette (and therefore the sprocket) is coupled with the hub sleeve by a mechanism known in technical jargon as "freewheel".

The freewheel allows the rotation of the sprocket to be transmitted to the rear wheel when the rotational speed of the sprocket is equal to the rotational speed of the rear wheel, and allows the movement between the sprocket and the rear wheel to be disengaged when the rotational speed of the sprocket is different from the rotational speed of the wheel.

Thus, the freewheel allows the sprocket (and the cassette) and the rear wheel to move as a unit only when the sprocket is set to rotate in the direction of rotation of the rear wheel and at the same speed as the wheel, while it does not have any effect on the rear wheel, which continues its rotation by inertia and does not force the rider to keep the legs moving to assist the rotation of the rear wheel, when the sprocket is set to rotate in the opposite direction or for a lower rotational speed than the wheel.

One type of freewheel provides an annular body that rotates as a unit with the cassette (and thus with the sprocket), and an annular body that rotates as a unit with the rear wheel (and thus with the hub sleeve). The two annular bodies rotate about the same axis of rotation, which substantially coincides with the axis of rotation of the hub sleeve of the rear wheel.

In the freewheel with front clutch, the two ring bodies have respective axial teeth facing each other. Such teeth are shaped so that, when the sprockets are axially engaged with each other, they transmit the driving torque from the annular body constrained to the box to the annular body constrained to the rear wheel when the sprocket rotates in a first angular direction, thus transmitting the rotation of the sprocket to the rear wheel when the cyclist exerts a propulsive action on the pedals. When the rotation speed of the sprocket in the first angular direction is less than the angular speed of the rear wheel or when the sprocket rotates in the second angular direction, the axial teeth do not transmit any driving torque between the two annular bodies, thus allowing free rotation of the rear wheel when the rider stops his/her propulsion action on the pedals or when he/she actuates the pedals in a direction opposite to the propulsion direction.

Typically, the axial teeth are shaped according to a circumferential path comprising a series of inclined planes separated by substantially axial planes to form a substantially "sawtooth" geometry. During rotation in a first angular direction, the axial plane of the annular body fixedly connected to the sprocket abuts against the axial plane of the annular body fixedly connected to the rear wheel, thereby transmitting the movement of the sprocket to the rear wheel. During rotation of the sprocket in the second angular direction or when the rotational speed of the sprocket in the first angular direction is less than the angular speed of the rear wheel, the inclined plane of the annular body fixedly connected to the sprocket slides over the inclined plane of the annular body fixedly connected to the rear wheel, thereby interrupting the transmission of motion between the sprocket and the rear wheel.

After sliding between the inclined planes, the two annular bodies move axially apart and the axial teeth lose contact with each other.

In order to re-couple the axial teeth to each other (a condition necessary to transmit the motion from the sprocket to the rear wheel), the free wheel generally comprises an elastic or magnetic element arranged in the radial space occupied by one of the annular bodies and which exerts a constant or intermittent axial pushing action on one of the annular bodies towards the other annular body.

This axial pushing action allows the re-coupling of the annular bodies when the cyclist resumes the propelling action.

Examples of magnetic return means are described in documents US 2014/0062164 and US 2017/0015137.

The applicant has noticed that the use of the free wheel described above results in a dissipation of the kinetic energy of the rear wheel, even up to the order of 2 watts at a speed of about 50Km/h, when the cyclist stops applying the propulsive action.

This dissipation of kinetic energy has a negative effect on the cyclist's performance, forcing him/her to make greater efforts to compensate for the dissipated kinetic energy.

The applicant has verified that this dissipation of kinetic energy can be due to a substantially continuous and constant sliding of the inclined planes of the axial teeth of the annuli on the inclined planes of the axial teeth of the other annulus, when the rider has stopped his propulsive action.

The applicant believes that such slippage between the axial teeth is due to the axial pushing action exerted by the elastic or magnetic element on one toroidal body towards the other.

The applicant has indeed verified that such an axial pushing action triggers a repetitive process (which stops only when the cyclist starts again to exert a pushing action), during which each movement axially separating the two annular bodies is accompanied by an immediate return of the two annular bodies together, during which the inclined planes of the two annular bodies slide over each other, dissipating energy.

Disclosure of Invention

Accordingly, the present invention relates to a freewheel assembly with front clutch for a bicycle, comprising:

a hub sleeve rotatably mounted on the hub pin about an axis of rotation; and a cartridge rotatably mounted on the hub pin;

a first annular body rotatable about a rotation axis in a first angular direction and a second angular direction, the first annular body being rotatably inserted on the hub pin and comprising a first crown gear;

a second annular body rotationally coupled with the hub sleeve and including a second crown gear mating with and axially facing the first crown gear;

said first annular body being axially movable with respect to the second annular body between a transmission configuration, in which the first crown gear is coupled with the second crown gear, and a free-wheel configuration, in which the first crown gear is uncoupled from the second crown gear and the first annular body does not transmit motion to the second annular body;

a coupling member operating between the first annular body and the cassette;

wherein rotation of the cassette relative to the first annular body forces the coupling member to axially translate the first annular body toward the second annular body when the first annular body is in the free-wheel configuration,

and wherein the magnetic component is configured to inhibit rotation of the first toroid relative to the hub pin.

When the first toroidal body is in the transmission configuration and the rider applies a propelling action, the rotation applied to the box is transmitted to the first toroidal body, which sets the second toroidal body, and therefore the hub sleeve, to rotate in a first angular direction.

When the rider interrupts the propulsion action, the second annular body pushes the first annular body in an axially outward direction (by interference between the crown gears of the two annular bodies), disengaging the cassette from the second annular body (and therefore from the hub sleeve). Thus, the first annular body reaches a free wheel configuration.

The applicant has perceived that by arranging the coupling means for axially translating the first annular body towards the second annular body in the event of a rotation of the cassette with respect to the first annular body, the first annular body is stably maintained in the free-wheel configuration (and does not tend to return into the transmission configuration) until the moment when such relative rotation occurs.

The applicant has found that by arranging the magnetic component that blocks the rotation of the first annular body with respect to the hub pin, the first annular body is moved axially towards the second annular body (and therefore towards the transmission configuration) only when the cyclist starts the propulsion action again.

In fact, when the first toroidal body is in the free-wheel configuration, because the cyclist has stopped pedaling, the box is stationary and the first toroidal body is also stationary. Thus, the relative speed of the cassette with respect to the first annular body is zero.

When the rider begins the propulsion action again, the box rotates relative to the hub pin. The first toroidal body will tend to be dragged in rotation by the cartridge, but is braked by the magnetic means which prevent the rotation of the first toroidal body with respect to the hub pin. The net effect is that the cassette rotates relative to the first annular body.

In this way, when the propulsion action is started again on the pedals of the bicycle, the first annular body is axially translated towards the second annular body.

This avoids continuous or intermittent contact of the first annular body against the second annular body when no propelling action is applied to the pedals of the bicycle, and prevents the first annular body from engaging the second annular body when propelling action is started again.

The member of the freewheel assembly is configured to rotate about an axis of rotation that coincides with an axis of rotation of a rear wheel of the bicycle. Such axis of rotation is the main reference axis of the element forming part of the invention; all indications of direction etc., such as "axial", "radial", "circumferential" and "diameter" will be given with respect to such an axis of rotation. References to the radial directions to "outward", "outside" and "inward" and "inside" should be interpreted as away from or towards the axis of rotation, respectively. References to axial direction to "outward", "outside" and "inward" and "inside" should be interpreted as being away from a radial mid-plane of the wheel of the bicycle or towards such a radial plane (when the wheel is in use), respectively. With respect to the rotation axis, two opposite rotation directions are defined, in particular a first angular direction (which preferably coincides with the angular rotation direction of the rear wheel allowing the bicycle to move forward) and a second angular direction.

The invention can include one or more of the following preferred features, used alone or in combination.

Preferably, said magnetic means act between the hub pin and the first annular body.

In this way, the magnetic components exert their action directly between the hub pin and the first annular body.

Preferably, the magnetic parts are "contactless", i.e. they exert their action between the hub pin and the first annular body without any physical contact between these two elements or without any element or any auxiliary body directly in contact with the hub pin and the first annular body.

Preferably, the magnetic component is configured to apply a resistive torque that resists rotation of the first annular body relative to the hub pin. Preferably, such a resistance torque is less than a predetermined drive torque adapted to rotate the first ring body relative to the hub pin.

The torque applied by the magnetic component is a braking torque. In other words, the magnitude of the torque exerted by the magnetic component is less than the drive torque that the rider typically transmits to the cartridge during a propelling action.

In other words, the magnetic means prevent the first annular body from rotating with respect to the hub pin when the driving torque exerted by the rider on the pedal and transmitted to the box is less than a predetermined threshold value. When the driving torque applied by the rider is higher than such a predetermined threshold, the first annular body rotates with respect to the hub pin, since the magnetic means cannot prevent such rotation.

Such a predetermined threshold value is substantially constant (it does not substantially vary during use of the bicycle), and is configured to depend on the type of bicycle, the use that has to be made by it and possibly other factors or parameters.

In any case, such predetermined threshold value is chosen so as not to affect the performance of the cyclist, i.e. to avoid the braking action of the magnetic component being perceptible (or as imperceptible as possible) to the cyclist.

For example, such a predetermined threshold value can have a value comprised between 1N/m and 50N/m, preferably comprised between 5N/m and 35N/m, more preferably comprised between 10N/m and 25N/m, more preferably about 20N/m.

Without being limited to a specific example, it has been estimated that the rider can apply a driving torque of up to 600N/m during climbing; it is estimated that a resistance torque of about 20N/m is provided by the magnetic component during climbing, which is not actually felt by the rider. Furthermore, such values are also rarely perceived during a propelling action on flat terrain.

Preferably, the first annular body has a predetermined axial dimension; said magnetic means act on a portion of the first toroidal body having an axial extension of at least 25% of said predetermined axial dimension when the first toroidal body is in the free-wheel configuration.

In other words, preferably, the magnetic means are able to exert the cited torque on the first toroidal body at least for an initial portion of the axial movement of moving the first toroidal body from the freewheel configuration to the transmission configuration.

Preferably, the coupling means comprise a plurality of guides having a volute or spiral extension operating between the first annular body and the box.

In this way, during the relative rotation between the capsule and the annular first body, the annular first body is axially moved with respect to the capsule.

Without being bound by any theory, the applicant has realized that the volute extension of the coupling member triggers the movement of the first annular body towards the second annular body when the cyclist starts the propelling action again. When the rider starts the propulsion action again, the box is set to rotate at the same angular speed as the rear wheel. Due to the torque exerted by the magnetic component (in this case the braking torque), the first annular body does not rotate as a unit with the cartridge, but follows the spiral or helical trajectory given by the coupling component. Such a trajectory has a circumferential component and an axial component. The axial component determines the translation of the first annular body towards the second annular body, which continues until the cyclist exerts his/her propulsive action and until the first annular body contacts the second annular body (transmission configuration).

The contact between the crown gears of the two annular bodies creates a further constraint of the movement of the first annular body and in particular prevents further translation of the first annular body in the axially inward direction. Thus, the first annular body rotates as a unit with the cassette.

Preferably, the extension of said scroll guide in the axial direction is greater than or equal to the axial distance between the first and second crown gears when the first annular body is in the free-wheel configuration.

In this way, the first annular body can be guided axially by the coupling member to translate along the entire maximum distance separating the first annular body from the second annular body.

Preferably, the freewheel assembly comprises a holding magnet that operates axially on the first annular body to hold the first annular body in the freewheel position.

The holding magnet prevents the first annular body from accidentally translating towards the second annular body, for example due to vibrations or shocks to which the wheel of the bicycle is subjected during use.

The magnetic force of the holding magnet is selected to allow the first annular body to move towards the second annular body when the rider starts the propulsion action again.

Preferably, said magnetic means comprise at least one portion made of ferromagnetic material of said first annular body and at least one permanent magnet.

In a first preferred embodiment of the invention, the first annular body is at least partially made of ferromagnetic material.

Preferably, the portion made of ferromagnetic material of the first annular body is at least partially made of a steel alloy or an iron-nickel-aluminum alloy or an iron-silicon alloy or an iron-nickel alloy or a combination thereof.

Preferably, the magnetic component further comprises a magnetizing body fixedly connected to the hub pin, facing radially inside and axially outside the first annular body, so as to form a magnetic circuit passing through said first annular body.

The magnetic circuit passes through the magnetizing body and is closed in the first annular body.

Preferably, the magnetising body comprises a plurality of projections directed radially towards the first annular body, and wherein the first annular body comprises a plurality of projections directed radially towards the magnetising body; the radial distance between the projections of the first annular body and the projections of the magnetising body defines a gap (or air gap) in the magnetic circuit.

The gap separates the first annular body from the magnetized body such that the first annular body is capable of rotating and translating relative to the magnetized body.

Preferably, the projections of the first plurality of projections of the first annular body have the same radial and circumferential extension and are circumferentially separated from each other by the same distance, and the projections of the first plurality of projections of the magnetized body have the same radial and circumferential extension and are circumferentially separated from each other by the same distance.

The gaps (or air gaps) have different heights (in the radial direction) depending on the angular position of the first annular body with respect to the magnetized body. The alternation of the projections (and therefore of the gaps) in the circumferential direction generates a cogging torque between the first annular body and the magnetized body, and in particular at each gap of minimum height. Such cogging torque realizes the cited torque that prevents the rotation of the first magnetic body with respect to the hub pin.

Preferably, the permanent magnet magnetizes the magnetization element.

The type and strength of the permanent magnet are selected according to the distance between the protrusions of the first ring body and the protrusions of the magnetized body and the strength of the cogging torque desired.

Preferably, said holding magnet coincides with said permanent magnet of the magnetic component.

In another preferred embodiment of the invention, said magnetic means comprise a first magnet fixedly connected to the hub pin and at least one second magnet rotating as a unit with the first annular body and magnetically interacting with said first magnet.

The interaction between the first magnet and the at least one second magnet produces the referenced torque that resists rotation of the first annular body relative to the hub pin.

Preferably, the first magnet and the at least one second magnet have radially directed polarizations. In other words, the poles of the first and second magnets are aligned in the radial direction.

Preferably, the first magnets follow each other and are spaced apart from each other in the circumferential direction; the polarities of two circumferentially adjacent first magnets are opposite. In other words, two circumferentially adjacent first magnets have opposite poles in a radially inward direction and thus in a radially outward direction. Thus, two radially adjacent first magnets have respective magnetic fields whose magnetic field lines enter and leave the magnets radially.

Thus, as the first ring rotates relative to the hub pin, the second magnet enters the magnetic field of the first magnet, thereby being attracted thereto and tending to prevent further rotation of the first ring (achieving the recited torque that prevents rotation of the first ring relative to the hub pin). As the first ring body further rotates, the second magnet enters the magnetic field of the adjacent first magnet, thereby being repelled by the magnetic field in the direction of the next circumferentially adjacent first magnet having a magnetic field that again attracts the second magnet.

The type and strength of the first and second magnets and the circumferential distance between two circumferentially consecutive first magnets are selected according to the strength of the torque desired to be obtained to prevent rotation of the first annular body.

Preferably, the distance between two circumferentially consecutive first magnets is comprised between about 0.1 and 4 times the circumferential extension of the first magnets.

Preferably, a plurality of second magnets having the same polarity and preferably identical to each other are provided. The second magnets are preferably equally spaced from each other in the circumferential direction and the distance separating a second magnet from a circumferentially consecutive second magnet is an integer multiple of the distance separating two circumferentially adjacent first magnets.

Drawings

Other features and advantages of the present invention will become more apparent from the following description of the preferred embodiments of the present invention with reference to the accompanying drawings. In these drawings:

FIG. 1 is a perspective view of a first portion of a freewheel assembly according to the present disclosure;

FIG. 2 is a perspective cross-sectional view of a second portion of a freewheel assembly according to the present invention in a first embodiment;

FIG. 3 is a perspective cross-sectional view of a first embodiment of a freewheel assembly according to the present invention with portions removed to better highlight other portions;

FIG. 4 is a perspective cross-sectional view of a freewheel assembly according to the present invention in a first embodiment;

FIG. 5 is a cross-sectional view of a second embodiment of a freewheel assembly according to the present disclosure;

FIG. 6 is a cross-sectional view of the freewheel assembly of FIG. 5 in a different operating configuration;

FIG. 7 is a perspective cross-sectional view of a portion of the freewheel assembly of FIG. 6; and is

Fig. 8 is a perspective cross-sectional view of another portion of the freewheel assembly of fig. 6.

Detailed Description

A freewheel assembly with front clutch according to the present invention is indicated generally at 10.

The freewheel assembly 10 includes a hub sleeve 11, the hub sleeve 11 rotates as a unit with the rear wheel of the bicycle via one or more spoke holding flanges 12, which one or more spoke holding flanges 12 are constrained by the hub sleeve 11 or are integral with the hub sleeve 11.

Hub sleeve 11 is rotatably mounted about hub pin 13, for example by rolling bearings 14, for rotation in a first angular direction a and a second angular direction B opposite to first angular direction a. The first angular direction a coincides with the direction of rotation of the rear wheel of the bicycle when the bicycle is moving forward.

The hub pin 13 preferably intersects a hub pin (not shown) that fixedly connects the hub pin 13 to the frame of the bicycle. Thus, the hub sleeve 11 is rotatable about a rotational axis X that coincides with the rotational axis of the rear wheel of the bicycle.

The freewheel assembly 10 comprises a first annular body 15 and a second annular body 16, the second annular body 16 being arranged in an axially inward position with respect to the first annular body 15 and always functioning in an axially inward position.

The first annular body 15 is rotatably mounted on the hub pin 13 and comprises a first crown wheel 17 (illustrated in figures 2 and 8), the first crown wheel 17 having teeth 18 directed axially inwards towards the second annular body 16.

The teeth 18 have a "saw-tooth wave" profile, i.e. they comprise a series of first portions which are substantially flat and inclined with respect to the axial direction, which are spaced apart by second portions which are substantially flat in a plane parallel to the axis of rotation X.

The second annular body 16 is configured to rotate as a unit with the rear wheel of the bicycle and is constrained to rotate relative to the hub sleeve 11.

The second annular body 16 is axially more inward than the first annular body 15 and is axially aligned with the first annular body 15.

In a preferred embodiment of the present invention, as illustrated in fig. 1, the second annular body 16 is inserted into the circumferential recess 19 of the spoke holding flange 12 to rotate as a unit with the spoke holding flange 12.

To this end, the circumferential recess 19 of the spoke holding flange 12 comprises radially inner teeth 20 (better illustrated in fig. 3) defining a rack, and the second annular body 16 is equipped with a radially outer surface 21 having teeth 22 (illustrated in fig. 7), the teeth 22 being shaped to mate with the teeth 20 of the spoke holding flange 12.

The coupling between the teeth 20 of the spoke holding flange 12 and the teeth 22 of the second annular body 16 prevents relative rotation of the second annular body 16 with respect to the spoke holding flange 12 and the hub sleeve 11.

The second annular body 16 also comprises a second crown wheel 23, the second crown wheel 23 having teeth 24 directed axially towards the first annular body 15 and matching the teeth 18 of the first crown wheel 17.

The teeth 24 have a "saw-tooth wave" profile, i.e. they comprise a series of first portions which are substantially flat and inclined with respect to the axial direction, which are spaced apart by second portions which are substantially flat in a plane parallel to the axis of rotation X.

The first annular body 15 is movable in an axial direction with respect to the second annular body 16 between a transmission configuration and a free-wheel configuration.

In particular, when the first annular body is in the transmission configuration, the first annular body 15 transmits a rotation in the first angular direction a to the second annular body 16, whereas in the free-wheel condition, the first annular body 15 does not transmit any rotation to the second annular body 16.

In other words, in the transmission configuration, the angular speed of the first annular body 15 in the first angular direction a is equal to the angular speed of the second annular body 16 in the first angular direction a.

In this regard, the teeth 18 of the first annular body 15 and the teeth 24 of the second annular body 16 are configured so that, when the first crown gear 17 is in contact with the second crown gear 23, the first annular body 15 is able to transmit a rotation in the first circumferential direction a to the second annular body 16, and is unable to transmit a rotation in the second circumferential direction B to the second annular body 16.

For a relative rotation of the first annular body 15 with respect to the second annular body 16 in the second angular direction B, the respective first portions of the teeth 18, 24 slide on one another while the respective second portions cannot abut on one another, thus allowing the first annular body 15 to rotate freely with respect to the second annular body 16.

It should be noted that the sliding of the teeth 18 of the first annular body 15 on the teeth 24 of the second annular body 16 determines the axial sliding of the first annular body 15 with respect to the second annular body 16 in the axially external direction.

In the free-wheel configuration, the axial position of the second annular body 16 is the same as the axial position occupied by the second annular body 16 in the transmission configuration.

In the free-wheel configuration, the first toroidal body 15 reaches a more outward axial position with respect to the axial position occupied by the first toroidal body 15 when in the transmission configuration.

The first toroidal body 15 is associated with the box 25, so that when the first toroidal body 15 is in the transmission configuration, the rotation of the box 25 in the first angular direction a is transmitted to the second toroidal body 16 and therefore to the rear wheel of the bicycle.

The case 25 is configured to support and be rotated by a gear set (cogset) (not shown).

The case 25 can be a substantially cylindrical body equipped with a plurality of axially directed grooves on which the gear set is fitted and axially retained by a ring nut, or the case 25 can be a small body to which the integral gear set is rigidly connected. In other embodiments, the cartridge 25 can be integrated in a gear set, i.e. it can be integrated with a gear.

In any case, the cartridge is set in rotation about the rotation axis X by the sprocket of the gear set, is rotatably mounted on the hub pin 13 and is axially constrained to the hub pin 13 without being able to translate with respect to the hub pin 13.

In the embodiment illustrated in the figures, the box 25 comprises a radially outer portion 26 and a radially inner portion 27. The radially inner portion 27 rotates as a unit with the hub pin 13, and the radially outer portion 26 is mounted on the radially inner portion 27 by a rolling bearing 27a, the rolling bearing 27a allowing the radially outer portion 26 to rotate about the rotation axis X relative to the radially inner portion 27. The gear set rotates with the radially outer portion 26 of the case 25 as a unit.

Thus, in the transmission configuration (illustrated in fig. 6), the first annular body 15 is able to transmit the rotary motion along the first angular direction a of the set to the second annular body 16.

In order to allow a translation of the first annular body 15 in the axial direction with respect to the second annular body 16, the freewheel assembly 10 comprises a coupling member 28 operating between the first annular body 15 and the cassette 25.

The coupling means 28 comprise a first portion 29 (fig. 7) and a second portion 30 (fig. 3), the first portion 29 being arranged on a radially outer surface 30 of the first annular body 15 and the second portion 30 being arranged on a radially inner surface 31 of the box 25.

A radially inner surface 31 of the box is formed in a substantially cylindrical circumferential recess 32 of the box 25 axially facing the first annular body 15.

As shown in fig. 3, the radially inner surface 31 of the cartridge 25 includes a first plurality of recesses 33 alternating with a first plurality of projections 34.

The radially external surface 30 of the first annular body 15 is annular and comprises a second plurality of projections 35 alternating with a second plurality of recesses 36, the second plurality of projections 35 and the second plurality of recesses 36 matching respectively the first plurality of recesses 33 and the first plurality of projections 34 of the radially internal surface 31 of the box 25.

The first plurality of protrusions 34 are inserted into the second plurality of recesses 36 and the second plurality of protrusions 35 are inserted into the first plurality of recesses 33.

The first 33 and second 36 pluralities of recesses and the first 34 and second 35 pluralities of projections have a substantially helical or spiral extension and form a guide 37 (fig. 2), the guide 37 having a helical or spiral extension for the relative movement between the cartridge 25 and the first annular body 15.

In this way, the relative rotation between the box 25 and the first toroidal body 15 also generates an axial translation of the first toroidal body 15.

In other words, the relative movement between the capsule 25 and the first toroidal body 15 is a rotational translation.

In particular, guide 37, which has a helical extension, is oriented so that a rotation of box 25 in a first angular direction a with respect to first toroidal body 15 corresponds to a translation of first toroidal body 15 in an axially internal direction, whereas a rotation of box 25 in a second angular direction B with respect to first toroidal body 15 corresponds to a translation of first toroidal body 15 in an axially external direction.

It should be noted that when the teeth 18 of the first crown 17 engage the teeth 24 of the second crown 23 (transmission configuration), the translation of the first annular body 15 in the axially inward direction is interrupted, since the second annular body 16 and the box 25 are axially fixed, in other words they are not able to move.

In this regard, in order to allow the coupling means 28 to axially guide the first annular body 15 until the first annular body 15 comes into contact with the second annular body 16 so as to reach the motion transmission state, the extension of the guide 37 in the axial direction is greater than or equal to a distance in the axial direction separating the position of the first annular body 15 when in the free-wheel state and the position of the first annular body 15 when in the motion transmission state.

In a preferred embodiment of the invention, the second plurality of projections 35 and the second plurality of recesses 36 formed on the radially outer surface 30 of the first toroidal body 15 extend in the axial direction by a distance greater than or equal to a distance in the axial direction separating the position of the first toroidal body 15 when in the free-wheel condition and the position of the first toroidal body 15 when in the motion transmission condition. The second plurality of projections 35 and the second plurality of recesses 36 formed on the radially outer surface 30 of the first annular body 15 in turn extend in the axial direction less than the first plurality of recesses 33 and the first plurality of projections 34 formed on the radially inner surface 31 of the box 25.

In order to trigger the rotation of cartridge 25 with respect to first annular body 15 in first angular direction a, freewheel assembly 10 comprises magnetic means 38, magnetic means 38 acting on first annular body 15 and configured to exert on it a torque that prevents the rotation of first annular body 15 with respect to hub pin 13.

Magnetic member 38 acts on first toroidal body 15 to counteract the tendency of box 25 to pull first toroidal body 15 in rotation, i.e. to prevent box 25 and first toroidal body 15 from rotating as a single body (when first toroidal body 15 is in the free-wheel configuration).

The magnetic member 38 cannot prevent the rotation of the cartridge 25 about the rotation axis X with respect to the hub pin 13.

In particular, the braking torque exerted by the magnetic means 38 on the first annular body 15 is lower than a predetermined driving torque exerted by the cyclist and suitable for rotating the first annular body 15 with respect to the hub pin 13. Such predetermined driving torque can have a value comprised between 1N/m and 50N/m, preferably comprised between 5N/m and 35N/m, more preferably comprised between 10N/m and 25N/m, more preferably about 20N/m. When the first toroidal body is in the free-wheel configuration, magnetic part 38 acts on a portion of first toroidal body 15 having an axial extension of at least 25%, preferably at least 35%, even more preferably at least 50%, even more preferably at least 65%, even more preferably at least 80%, even more preferably 100% of the overall axial dimension of first toroidal body 15.

In a preferred embodiment of the invention, a portion of the path of the magnetic component 38 in the axial direction, followed by the first annular body 15, in the passage from the freewheel configuration to the transmission configuration, acts. A portion of such path in the axial direction has an extension of at least 25%, preferably at least 35%, even more preferably at least 50%, even more preferably at least 65%, even more preferably at least 80%, even more preferably 100% of the entire path in the axial direction followed by the first annular body 15.

In a first embodiment of the invention (better illustrated in fig. 2 to 4), the magnetic component 38 comprises a magnetized body 39 fixedly connected to the hub pin 13. The magnetized body 39 can be an insert fitted to the hub pin 13 or the magnetized body 39 can be integral with the hub pin 13. In any case, the magnetising body is an annular body extending circumferentially around the hub pin 13. The magnetized body 39 comprises a first portion 40 and a second portion 41 (fig. 2), the first portion 40 extending substantially parallel to the hub pin 13, the second portion 41 extending from an axially outer end of the first portion 40 substantially perpendicular to the first portion 40.

The magnetic part 38 also comprises at least one portion 15a, 15b of the first annular body 15 made of ferromagnetic material.

In particular, as shown in fig. 2, the first annular body 15 comprises a radially inner portion 15a and an axially outer portion 15b, the radially inner portion 15a facing radially towards the first portion 40 of the magnetizing body 39 and the axially outer portion 15b facing axially towards the second portion 41 of the magnetizing body.

In this embodiment, the radially inner portion 15a and/or the axially outer portion 15b of the first annular body 15 form at least one portion of the cited first annular body 15 made of ferromagnetic material. Preferably, the first annular body 15 is made substantially entirely of ferromagnetic material, so that the magnetic circuit passes through the magnetizing body 39 and the first annular body 15.

In particular, the first annular body 15 is at least partially made of a steel alloy, or an iron-nickel-aluminum alloy, or an iron-silicon alloy, or an iron-nickel alloy, or a combination thereof.

The radially inner portion 15a of the first annular body 15 comprises a plurality of projections 42 (fig. 4) circumferentially separated from one another, the plurality of projections 42 being radially directed towards the first portion 40 of the magnetizing body 39.

The first portion 40 of the magnetizing body 39 comprises a plurality of projections 43 circumferentially spaced from each other, the plurality of projections 43 being radially directed towards the first annular body 15.

The height of the plurality of projections 42 of the first annular body 15 and of the plurality of projections 43 of the magnetized body 39 in the radial direction is such as to avoid mechanical interference between the first annular body 15 and the magnetized body 39, thus allowing the first annular body 15 to rotate with respect to the magnetized body 39.

The projections 42 of the plurality of projections 42 of the first annular body 15 have the same extension in the radial and circumferential directions and are circumferentially separated from each other by the same distance.

The protrusions 43 of the plurality of protrusions 43 of the magnetized body 39 have the same extension in the radial and circumferential directions and are separated from each other in the circumferential direction by the same distance.

The circumferential extension and circumferential distance of the projections 42 of the annular body 15 are the same as the circumferential extension and circumferential distance of the projections 43 of the magnetizing body 39.

The plurality of projections 42 of the first ring body 15 and the plurality of projections 43 of the magnetized body 39 define a plurality of gaps in the magnetic circuit.

Gaps of different sizes are formed according to the angular position occupied by the first annular body 15 with respect to the magnetized body 39, and therefore according to the angular position occupied by the plurality of projections 42 of the first annular body 15 with respect to the projections 43 of the magnetized body 39.

In particular, the gap in the magnetic circuit has a minimum size when the projections 42 of the first annular body 15 are radially aligned with the projections 43 of the magnetizing body 39, and a maximum size when the projections 42 of the first annular body 15 are not radially aligned with the projections 43 of the magnetizing body 39.

The projections 42 of the annular first body 15 extend in the axial direction over a portion of the annular first body 15 over at least 25%, preferably at least 35%, even more preferably at least 50%, even more preferably at least 65%, even more preferably at least 80%, even more preferably 100% of the overall axial dimension of the annular first body 15.

The projection 43 of the magnetizing body 39 extends in the axial direction on a portion of the path in the axial direction followed by the first annular body 15 in the passage from the freewheel configuration to the transmission configuration. A portion of such path in the axial direction has an extension of at least 25%, preferably at least 35%, even more preferably at least 50%, even more preferably at least 65%, even more preferably at least 80%, even more preferably 100% of the entire path in the axial direction followed by the first annular body 15.

The rotation of the first annular body 15 with respect to the magnetized body 39 determines a "cogging" in the magnetic circuit passing through the magnetized body 39 and the first annular body 15, which tends to keep the projections 42 of the first annular body 15 radially aligned with the projections 43 of the magnetized body 39, thus braking the rotation of the first annular body 15.

The magnetizing body 39 is made of ferromagnetic material and is magnetized by a permanent magnet 44, the permanent magnet 44 preferably being in direct contact with the magnetizing body 39.

In a preferred embodiment of the invention, the permanent magnet 44 is arranged in an axially external position with respect to the first annular body 15 and has an axially directed polarity, i.e. the poles of the magnet are aligned in the axial direction.

In this way, the permanent magnets 44 and the magnetized bodies 39 axially attract the first ring body 15 in the axially outward direction, thereby forming a holding magnet for the first ring body 15.

In a second embodiment of the invention (better illustrated in fig. 5 to 8), the magnetic component 38 comprises a first magnet 45 fixedly connected to the hub pin 13. The first magnets 45 are circumferentially spaced apart from each other along the entire circumferential extension of the hub pin 13 (as illustrated in fig. 7).

The first magnets 45 are polarized in the radial direction, i.e. they have poles aligned in the radial direction with alternating polarity.

In other words, two circumferentially adjacent first magnets 45 have opposite polarities such that a first magnet 45 has a magnetic field oriented in a radially inward direction (into the hub pin 13) and the other circumferentially adjacent first magnet 45 has a magnetic field oriented in a radially outward direction (out from the hub pin 13).

The first magnets 45 have the same size as each other.

The first magnet 45 extends in the axial direction on a portion of the path in the axial direction followed by the first annular body 15 in the passage from the free wheel configuration to the transmission configuration. A portion of such path in the axial direction has an extension of at least 25%, preferably at least 35%, even more preferably at least 50%, even more preferably at least 65%, even more preferably at least 80%, even more preferably 100% of the entire path in the axial direction followed by the first annular body 15.

The circumferential distance between two circumferentially consecutive first magnets 45 is comprised between about 0.1 and 4 times, preferably 0.2 and 3 times, more preferably 0.3 and 2.5 times, more preferably 0.5 and 1.5 times, more preferably about 1 times the circumferential extension of the first magnets 45.

In this embodiment, the magnetic means 38 also comprise a second magnet 46, the second magnet 46 rotating as a unit with the first annular body 15 and magnetically interacting with the first magnet 45 (better illustrated in fig. 7).

The second magnet 46 is arranged on the radially inner portion 15a of the first annular body 15 and preferably faces radially towards the first magnet 45.

The second magnet 46 extends axially on the first annular body 15 for a portion of the first annular body 15 that is at least 25%, preferably at least 35%, even more preferably at least 50%, even more preferably about 65% of the overall axial dimension of the first annular body 15.

Preferably, the plurality of second magnets 46 are disposed equidistantly circumferentially spaced from one another. The circumferential position of the second magnets 46 on the first annular body 15 is such that when a second magnet is radially aligned with a first magnet 45, the other second magnets 46 are also radially aligned with the respective first magnet 45. In particular, when the second magnets 46 are radially aligned with the first magnets 45, all of the second magnets are radially aligned with respective first magnets 45 having the same polarity (i.e., all having a polarity radially entering the hub pin 13 or all having a polarity radially exiting the hub pin 13).

Like the first magnets 45, the polarity of the second magnets 46 is directed radially. The first magnet 45 and the second magnet 46 can be made of neodymium.

When the first ring 15 rotates relative to the hub pin 13, the second magnet 46 enters the magnetic field of the first magnet 45 and is attracted by the first magnet 45. Further rotation of the first annular body 15 is therefore hindered by the magnetic interaction between the first magnet 46 and the second magnet 46. When the first ring body 15 is further rotated against the attractive force between the first 45 and second 46 magnets, the second magnet 46 enters the magnetic field of the adjacent first magnet 45 and is repelled by the magnetic field in the direction of the next circumferentially adjacent first magnet 45 having a magnetic field that again attracts the second magnet 46.

Also in this embodiment, the permanent magnets 47 are arranged in an axially outer position with respect to the first annular body 15 and have axially directed polarities, i.e. the poles of the magnets 47 are aligned in the axial direction.

In this way, the permanent magnets form the holding magnets 47 for the first annular body 15.

In use, the freewheel assembly 10 with front clutch operates as described below.

During the propulsive pedaling by the cyclist, as illustrated in fig. 6, the first annular body 15 is in transmission configuration and is coupled in a rotatable manner with the second annular body 16.

In this case, the first crown 17 of the first annular body 15 is engaged with the second crown 23 of the second annular body 16, and the first annular body 15 transmits a rotary motion in the first angular direction a to the second annular body 16.

In this configuration, the first toroidal body 15 rotates as a unit with the box 25 (in the first angular direction a), since the first toroidal body 15 cannot translate in the axially inward direction due to the constraint provided by the second toroidal body 16.

It should be noted that during the rotation of the cartridge in the first angular direction a, the guide 37 allows the first toroidal body 15 to perform a possible axial translation only in the axially internal direction.

When the cyclist stops or slows down his/her propulsion action, the angular speed of the second annular body 16 (the second annular body 16 being fixedly connected to the rear wheel) in the first angular direction a is greater than the angular speed of the first annular body 15 in the same angular direction.

In this case, the teeth 18 of the first 17 and the teeth 24 of the second crown gear 23 slide on each other. This sliding tends to move the first annular body 15 axially away from the second annular body 16 and to bring the first annular body 15 into an outer axial position.

The movement of the first annular body 15 is accompanied by the coupling means 28 (and allowed by the coupling means 28). The guide 37 defined by the coupling means 28 imparts a movement to the first annular body 15 along a helical trajectory that axially translates the first annular body 15 outwards and rotates the first annular body 15 by a few degrees in the second angular direction B with respect to the box 25.

When the first 17 and second 23 crown gears no longer interfere with each other, the axial movement of the first annular body 15 is interrupted.

In this position, the first annular body 15 reaches the free wheel configuration illustrated in fig. 4 and 5.

In this case, the second annular body 16 rotates independently of the first annular body 15, without mechanical interference (and therefore without dissipation of energy) between them.

The first annular body 15 is also held in the free wheel configuration by the holding magnets 44, 47.

When the cyclist starts to exert the propulsive action again by rotating the box in the first angular direction a at the same angular speed as the rear wheel, the box 25 tends to pull the first annular body 15 in rotation.

The magnetic means 38, whether they are configured as described with respect to the first embodiment or the second embodiment, prevent the rotation of the first annular body 15 with respect to the hub pin 13, thus tending to brake the first annular body 15 with respect to the box 25.

The constraint between the box 25 and the first annular body 15, achieved by the coupling means 28, and in particular by the guide 37, forces the first annular body 15 to translate in an axially inward direction following the rotation of the box 25 in the first angular direction a with respect to the annular body 15.

Thus, the first annular body 15 leaves the freewheel configuration to reach the transmission configuration again.

Naturally, a man skilled in the art can bring numerous modifications and variants to the invention described above, in order to satisfy specific and contingent requirements, all of which are in any case covered by the scope of protection of the invention, as defined by the following claims.