A freewheeling system for a bike

Abstract

The present invention relates to a freewheeling system (101) for a bike. The system comprises a circular ratchet part (102) and a circular pawl part (103). Said ratchet part comprises teeth (105) circularly disposed. Said pawl part comprises at least one circular pawl unit comprising pawl members (107) circularly disposed. Pawl members comprise a body having a fixed end (108) and a hook-shaped free end (109) and extend along a mutual plane perpendicular to a common rotational axis. The pawl members have an engaged configuration and a disengaged configuration relative to the teeth of the ratchet part. At least a portion of the body of each of the pawl members is a spring such that the pawl members are arranged to be adjusted from the engaged configuration to the disengaged configuration upon relative rotation between said ratchet part and said pawl part in a free relative rotational direction around said common rotational axis (104).

Description

[0001] A FREEWHEELING SYSTEM FOR A BIKE

[0002] FIELD OF THE INVENTION

[0003] The present invention relates to a freewheeling mechanism for a bike, and to a bike (bicycles and e-bicycles) comprising such a freewheeling mechanism in its drivetrain.

[0004] BACKGROUND OF THE INVENTION

[0005] Today’s most common / successful freewheeling mechanisms for bike drivetrains, where the term bikes also includes e-bikes, are the following, and they each have the disadvantages described below.

[0006] DT-Swiss’s Star-Ratchet freehub, where two saw-toothed / ramped surfaces / discs are pushed together by one or more springs for multiple simultaneous contact-point torque transmission. These systems generally offer a relatively low count of engagement points per rotation and are therefore not the most responsive towards rider pedaling input. Adding substantially more engagement points, while preserving a secure pedaling engagement between the ramped torque carrying surfaces, increases weight and / or freewheeling friction of this freewheeling technology. As the ramped surfaces would have to grow in diameter / size and / or have a larger force pushing them together to achieve a secure pedaling engagement. As a result, the three most common versions of the Star-Ratchet system have only 18 / 36 / 54 points of engagement per rotation (2071076.67° between engagement points). Furthermore, these systems are unforgiving in the sense that the engagement of the freehub is abrupt when it occurs. This results in high impact forces on the entire bike drivetrain when a rider e.g. goes into a powerful sprint, and thus also high impact forces on other parts of the bike such as the bike frame and rear wheel. These sharp impact forces are not energy efficient, and can damage equipment, that equipment consequently needs to be designed stronger and thus heavier to cope with these loads.

[0007] Chris King’s Ring Drive freehub, is a different take on the same fundamental saw-toothed / ramped surfaces / discs function as seen in Star-Ratchet. However, instead of merely relying on springs to push the interacting ramped sides / discs together for engagement, Ring Drive uses a worm drive to push the engaging sides firmly together under a pedaling load. This means that Ring Drive can lessen the freewheeling spring force seen in Star-Ratchet and thus achieve a lower freewheeling friction. The high compression between sides supplied by the worm drive also means that it becomes possible to introduce more points of engagement, for a quicker reacting hub. Chris King’s Ring Drive hubs commonly have 72 points of engagement (5°). However, this improvement in engagement speed comes at the cost of added mechanical complexity, cost and weight. Furthermore, as in the case of Star-Ratchet, these systems are unforgiving in the sense that the engagement of the freehub is abrupt when it occurs. This results in high impact forces on the entire bike drivetrain when a rider e.g. goes into a powerful sprint, and thus also high impact forces on other parts of the bike such as the bike frame and rear wheel. These sharp impact forces are not energy efficient, and can damage equipment, that equipment consequently needs to be designed stronger and thus heavier to cope with these loads.

[0008] Systems comprising a pawl and a ratchet ring are probably the most common freewheeling technology for bikes today. In such systems, one or more spring actuated pawls push outwards from the hub axle and up against a saw-toothed ratchet ring. This system is also (less commonly) sometimes reversed, so that the pawls are pushing inwards towards the hub axle and up against a saw-toothed ratchet ring. Pawl and ratchet freewheeling mechanisms are e.g. used by companies such as Zipp, Shimano, industry 9, E13, and several more. For durability, pawl and ratchet systems generally engage at least two pawls simultaneously. This spreads the load on these at least two pawls and corresponding ratchet teeth. Co-acting pawls are generally spaced equally apart, such as two co-acting pawls being 180° apart or three co-acting pawls being 120° apart. This balanced arrangement is to prevent excessive shear loads being applied to the axle of its hub. If e.g. a ratchet ring with 30 teeth is used against three pawl pairs (six pawls, two and two and two working together on opposing sides of the ratchet ring) the freewheeling system has 30*3 = 90 points of engagement per rotation. Notably, the current Industry Nine implementation of pawl and ratchet uses six pawls that each work independently and not in synch with other pawls. This results in a higher number of points of engagement, but at the same time results in higher loads on pawls / teeth and a hub axle that consequently need to be oversized to deal with the larger loads. Also notably, designs that use co-working pawls are also susceptible to occasional single-pawl engagement in use, as no manufacturing methods can theoretically be accurate enough to ensure a 100% reliable synchronization in pawl engagement. Pawl engagement mismatch can become more common over time as contact surfaces of pawls and ratchet ring wear unevenly. Said occasional single-pawl engagements in hubs that are designed to have co-working pawls can lead to damage of parts, as loads surpass intended design loads. Introducing more pawls, increasing the circumference of the ratchet ring and / or increasing the number of ratchet teeth all add to weight and freewheeling friction. As a result, pawl and ratchet systems are most commonly designed with between 18 and 60 points of engagement, however there are also fairly common MTB designs where quick engagement is prioritized more (above weight and friction) that can reach well above 100 points of engagement per rotation. Furthermore, as also is the case for aforementioned systems, pawl and ratchet systems are unforgiving in the sense that the engagement of the freehub is abrupt when it occurs. This results in high impact forces on the entire bike drivetrain when a rider e.g. goes into a powerful sprint, and thus also high impact forces on other parts of the bike such as the bike frame and rear wheel. These sharp impact forces are not energy efficient, and can damage equipment, that equipment consequently needs to be designed stronger and thus heavier to cope with these loads. Also furthermore, the non-forgiving engagement nature of the system means that the system cannot distribute loads effectively between multiple non-simultaneously engaging points of ratchet vs. pawls.

[0009] Other freewheeling mechanisms for bikes have enjoyed less commercial success, generally because of inferior performance, higher manufacturing cost and / or lower durability / reliability. One un-common freewheeling mechanism for a bike that is still worth mentioning is the LoopsDrive system by Soul-Kozak. It employs tension loaded loops that grab / loop around ratcheting teeth that are built into a cassette of a bike. This system has said loops exposed to the elements, and is thus not limited to the smaller size of a sealed freehub body, and said loops are thus intended to engage at a relatively large radius from the wheel rotational axis, to lessen the load on an engaged loop and thus enable each loop to act alone without experiencing extreme loads. Thus, not relying on the realistically difficult to achieve reliably simultaneous engagement of a plurality of loops, as most ratchet and pawl systems rely on to a varying degree of success. However, the large radius of the ratchet ring, that is intended / needed to allow reliable operations from a single loop engagement, adds weight to the system relative to a smaller ring. Furthermore, the LoopsDrive is unforgiving in the sense that the engagement is abrupt when it occurs. This results in high impact forces on the entire bike drivetrain when a rider e.g. goes into a powerful sprint, and thus also high impact forces on other parts of the bike such as the bike frame and rear wheel. These sharp impact forces are not energy efficient, and can damage equipment, that equipment consequently needs to be designed stronger and thus heavier to cope with these loads. Also furthermore, the system cannot distribute loads effectively between multiple non- simultaneously engaging points of ratchet vs. loops.

[0010] The inventor of the present invention has appreciated that there is thus a need for an improved bike freewheeling system.

[0011] SUMMARY OF THE INVENTION

[0012] It would be advantageous to achieve an improved, simplified, lightweight, quick engaging, smoothly engaging, low-friction, durable, and robust / reliable bike freewheeling system. In general, the invention preferably seeks to mitigate, alleviate or eliminate one or more of the above-mentioned disadvantages singly or in any combination. In particular, it may be seen as an object of the present invention to provide an improved design of a Pawl and Ratchet Ring freewheeling system that solves some or all of the above-mentioned problems, or other problems, of the prior art.

[0013] To better address one or more of these concerns, a first aspect of the invention relates to a freewheeling system for a bike, the freewheeling system comprising a circular ratchet part and a circular pawl part with a common rotational axis, said circular ratchet part comprising teeth circularly disposed on the ratchet part; and said circular pawl part comprising at least one circular pawl unit, each of the at least one circular pawl unit comprising pawl members circularly disposed, each of the pawl members comprising a body having a fixed end and a hook-shaped free end, as viewed in a direction parallel to said common rotational axis, distal to the fixed end, wherein the fixed end is attached to the rest of the pawl part, wherein the hookshape of the free end is arranged to engage with the teeth of the ratchet part, wherein each of the at least one circular pawl unit has all its pawl members extending from their respective fixed ends to their respective hook-shaped free ends along a mutual plane that is perpendicular to the said common rotational axis, wherein each of the pawl members of said pawl part extend from its fixed end to its hook-shaped free end in a direction consisting of a radial component R to the said common rotational axis and a circumferential component C around the said common rotational axis, wherein the teeth of the said ratchet unit extend as far or further in both opposite directions parallel to the said common rotational axis than the hook-shaped free ends of all the pawl members of said pawl part, wherein each of the pawl members is arranged to be under a radial pre-load by pushing against said ratchet part along the said radial direction R, wherein each of the pawl members has an engaged configuration and a disengaged configuration relative to the teeth of the ratchet part, wherein the engaged configuration of said each of the pawl members has its said hookshaped free end hooking onto at least one of the teeth of the said ratchet part, thereby loading that said each of the pawl members in tension when said freewheeling system for a bike is transmitting applied torque, and thus said each of the pawl members resisting relative rotation between said ratchet part and said pawl part around said common rotational axis, wherein at least a portion of the body of each of the said pawl members is a spring such that said each of the pawl members is arranged to be adjusted from the engaged configuration to the disengaged configuration upon relative rotation between said ratchet part and said pawl part in the free relative rotational direction around said common rotational axis, that is opposite to the said resisted torque transmitting relative rotation between said ratchet part and said pawl part, by the spring portion of the body of the said each of the pawl members bending against the radial direction R to displace its hook-shaped free end as it slips over ratcheting teeth of the said ratchet part.

[0014] Thus, providing a freewheeling system for a bike that is simple in construction, has no supplemental components or pivots to its pawl member engagement functionality, requires little or no maintenance beyond the potential occasional lubrication, and can be made lightweight, quickly engaging, smoothly engaging and robust / reliable.

[0015] In particular, by providing that at least a portion of the body of each of the pawl members is a spring, the number of parts required to implement a freewheeling system can be reduced in comparison with conventional freewheeling systems in which springs are provided separately from pawls. Thereby, both manufacturing and maintenance may be simplified.

[0016] Furthermore, the disclosed freewheeling systems allows facilitation of a large number of pawl members and a large number of teeth of the ratchet part. An increase of the number of pawl members can be, at least in part, attributed to having a portion of the body of the pawl members being a spring, which allows smaller spacing between pawl members since a separate spring can be omitted. In turn, a greater number of pawl members can provide a quicker engagement between the ratchet part and the pawl part, and can reduce the wear of the parts of the freewheeling system. Additionally, a greater number of pawl members ensures that the system can still be used in case one or a few pawl members fail to engage or break.

[0017] The number of pawl members can be particularly great in examples comprising more than one pawl unit having a common rotational axis. Freewheeling systems according to the present disclosure can allow straightforward implementation of several of such parallel pawl units.

[0018] As an example, the circular pawl part can be additively manufactures, for example in titanium or a titanium alloy. This permits the disclosed geometry of the pawl part to be straightforwardly manufactured while providing adequate strength and elasticity to the pawl members.

[0019] It is further advantageous to provide each of the pawl members with a tension spring component. This provides a smoother engagement between the ratchet part and the pawl part, and a greater tolerance to pawl engagement mismatch. A smoother engagement is both more comfortable for the rider, reduces requirements (such as size and strength) to the parts of the freewheeling system, and reduces risks of breaking the freewheeling system. Further, a tension spring component allows sequential engagement of pawl parts, which can both smoothen engagement even further, and allow the spacing between pawl members to mismatch the spacing between teeth, which in turn increases the points of engagement per rotation. Spreading loads on multiple sequentially engaging pawl members can reduce loads on individual pawl members and ratchet teeth, and thus enable superior reliability and longevity.

[0020] A tension spring component is alternatively referred to as a tension spring function or tension spring-function.

[0021] Preferably, the hook-shaped free ends are angled to grab onto the teeth of the ratchet part.

[0022] In one embodiment of said freewheeling system for a bike, said radial direction R is outwards from the said common rotational axis, thus the said ratchet part having a larger radius than said pawl part, or said radial direction R is inwards towards the said common rotational axis, thus the said pawl part having a larger radius than said ratchet part.

[0023] Thus, when R is outwards said ratchet part has a larger radius and can thus have more ratcheting teeth around its circumference and said pawl units of said pawl part has more space for its hook-shaped free ends, pushing up against said ratchet part, furthermore for R being outwards, if said pawl members are designed to have substantial circumferential tension spring-function, then the said hook-shaped free ends can grab more and more loosely onto ratcheting teeth as the relative engaged rotation between pawl part and ratchet part makes the grab angle of ratcheting teeth slacker as the relative rotation progresses, potentially providing an overload protection function for said pawl members. When R is inwards, the pawl part has a larger radius and thus the pawl units of the pawl part have more space for fixed ends of its pawl members, furthermore for R being inwards, if said pawl members are designed to have substantial circumferential tension spring-function, then the said hook-shaped free ends can grab more and more securely onto ratcheting teeth as the relative engaged rotation between pawl part and ratchet part makes the grab angle of ratcheting teeth sharper as the relative rotation progresses.

[0024] In one embodiment of said freewheeling system for a bike, the body of each of one or more of said pawl members has a tension spring-function in the circumferential direction around said common rotational axis derived from said body having a non-linear extension, as viewed in a direction parallel to said common rotational axis, from the fixed end to the hook-shaped free end.

[0025] Thus, enabling said pawl member to extend under torque being applied to the said freewheeling system and thus engaging smoothly and allowing one or more other pawl members, with a different rotational engagement location, to also engage and thus spread the load and allow a gradual smooth engagement of said freewheeling system.

[0026] In one embodiment of said freewheeling system for a bike, the body of each of one or more of said pawl members has a tension spring-function in the circumferential direction around said common rotational axis derived from said body extending from the fixed end to the hook-shaped free end in a direction that gradually goes from a more circumferential direction to a more radial direction, or goes from a more radial direction to a more circumferential direction relative to said common rotational axis.

[0027] Thus, enabling said pawl member to extend under torque being applied to the said freewheeling system and thus engaging smoothly and allowing one or more other pawl members, with a different rotational engagement location, to also engage and thus spread the load and allow a gradual smooth engagement of said freewheeling system.

[0028] In one embodiment of said freewheeling system for a bike, the body of each of one or more of said pawl members has a tension spring-function in the circumferential direction around said common rotational axis derived from said body extending from the fixed end to the hook-shaped free end in a wave shaped manner, where the radial component of the extension direction alternates 1 or more times between the opposite radial directions relative to said common rotational axis.

[0029] Thus, enabling said pawl member to extend under torque being applied to the said freewheeling system and thus engaging smoothly and allowing one or more other pawl members, with a different rotational engagement location, to also engage and thus spread the load and allow a gradual smooth engagement of said freewheeling system. Said wave shape offering the benefit of stiffness and strength of said pawl member in the circumferential direction ramping up as said pawl member extends, as the wave shape become shallower with the extension and thus the bending moment on the extremities of the wave shape of said pawl members lessens.

[0030] In one embodiment of said freewheeling system for a bike, the body of each of one or more of said pawl members has a tension spring-function in the circumferential direction around said common rotational axis derived from said body extending from the fixed end to the hook-shaped free end in a wave shaped manner, where the radial component of the extension direction alternates 2 or more times between the opposite radial directions relative to said common rotational axis.

[0031] Thus, enabling said pawl member to extend under torque being applied to the said freewheeling system and thus engaging smoothly and allowing one or more other pawl members, with a different rotational engagement location, to also engage and thus spread the load and allow a gradual smooth engagement of said freewheeling system. Said wave shape offering the benefit of stiffness and strength of said pawl member in the circumferential direction ramping up as said pawl member extends, as the wave shape become shallower with the extension and thus the bending moment on the extremities of the wave shape of said pawl members lessens. Having multiple waves in the wave shape gives further circumferential spring-function.

[0032] In one embodiment of said freewheeling system for a bike, each of the said pawl members have an overload protection function derived from a substantial portion of its pawl member body being located far enough in a direction opposite to said radial direction R from a straight line drawn from the center of the fixed end of said each of the said pawl members to its hook-shaped free end’s engagement point to said ratchet part, such that the bending of said each of the said pawl members under extreme torque transmitting loads results in a twist of its hook-shaped end so it slips out and unhooks from engagement.

[0033] Thus, said overload protection functionality saving / protecting said each of the said pawl members in potential cases where said freewheeling system is designed to share torque load on multiple pawl members but something, such as part construction inaccuracy or some wear or debris hindering optimal functionality, caused the freewheeling system to have fewer than planned / designed for co-acting engagements. Then this overload protection allows the freewheeling system to progress beyond the partially failed engagement and onto the next subsequent engagement point in its rotation, where pawl members should be safely ready for engagement.

[0034] In one embodiment of said freewheeling system for a bike, one or more of said pawl members comprise two or more hook-shapes on their distal free end.

[0035] Thus, spreading load of said one or more pawl members on more ratchet teeth and more hook ends.

[0036] In one embodiment of said freewheeling system for a bike, one or more of said pawl members each comprises at least one slit or gap providing an opening in a direction parallel to said common rotational axis and extending in a lengthwise direction between the free end and the fixed end such that a material thickness of the pawl member transverse to said lengthwise direction on each side of the pawl member is substantially similar.

[0037] Thus, by making said one or more pawl members effectively constructed of two or more substantially parallel leaf springs, a pawl member can be made significantly more flexible to applied bending moment loads while maintaining a given tension strength. This, in turn, can make said freewheeling system substantially more forgiving towards sudden input loads and furthermore enable it to more efficiently spread loads between its multiple pawl members.

[0038] In one embodiment of said freewheeling system for a bike, each of the pawl members of said pawl part extend from its fixed end to its hook-shaped free end in said radial direction R a distance of but not limited to 2-30mm, such as 5-16mm, and in direction C circumferential around the common rotational axis a distance of 10-60mm, such as 15-40mm, and the thickness of each of the pawl members of said pawl part measured in the direction of said common rotational axis is 1-80mm, such as 2-20mm, and the width of the body of each of said pawl members of said pawl part measured perpendicularly to its extension direction from fixed end to hook-shaped end, as viewed in a direction parallel to said common rotational axis, is 0.2-10mm, such as 1-5mm, and the radius from the said common rotational axis to the tips of said teeth of said ratchet part is 10-80mm, such as 20- 50mm.

[0039] Thus, being appropriately sized to fit on bikes without excess bulkiness and appropriately sized to also be able to deal with the loads present.

[0040] In one embodiment of said freewheeling system for a bike, said pawl part comprises at least two pawl units wherein each of the said at least two pawl units are offset from each other along said common rotational axis such that there are up to 20mm, such as up to 5mm, between adjacent said at least two pawl units measured parallel to said common rotational axis.

[0041] Thus, spreading loads on more pawl members of more pawl units within its pawl part, resulting in a freewheeling system for a bike that is quicker engaging and is also more robust to occasional failure of individual pawl members to engage. If said freewheeling system for a bike is designed to have a very high number of lightly- acting co-acting pawl members under high pedaling torque, such as 10-100 or more pawl members, then it becomes mechanically acceptable if pawl members occasionally fail to engage as there are so many others making up for it, which subsequently means that said pawl members can be designed to have a lighter radial push on said ratchet part, as they don’t need to be guaranteed to always engage safely, this consequently means that said freewheeling system for a bike can have lower freewheeling friction, less wear, and more silent operation.

[0042] In one embodiment of said freewheeling system for a bike, said pawl part comprises 3-50 pawl units, such as 4- 18 pawl units wherein each of the pawl units are offset from each other along said common rotational axis such that there are up to 20mm between adjacent pawl units measured parallel to said common rotational axis.

[0043] In one embodiment of said freewheeling system for a bike, all said fixed ends of all pawl members are rigidly connected to one another via the central portion of said pawl part.

[0044] Thus, spinning together with constant relative dimensions of all said fixed ends of all pawl members, of all of its one or more pawl units, towards each other.

[0045] In one embodiment of said freewheeling system for a bike, said pawl part is formed as a single continuous body that is rigid between all said fixed ends of all said pawl members.

[0046] Thus, spinning together with constant relative dimensions of all said fixed ends of all pawl members, of all of its one or more pawl units, towards each other and simultaneously limiting excess weight, bulkiness, material transition areas prone to failure, and assembly complexity. In one embodiment of said freewheeling system for a bike, manufacturing of said pawl part comprises additive manufacturing, such as 3d printing.

[0047] Thus, enabling economical and high-quality construction of a pawl part having multiple pawl units without any assembly or joining of parts being required, thus enabling a lightweight and compact pawl part with multiple pawl units.

[0048] In one embodiment of said freewheeling system for a bike, one or more of said pawl members have a varying thickness measured in the direction parallel to said common rotational axis, where said thickness is greater closer to the fixed end and lesser closer to the hook-shaped free end.

[0049] Thus, creating a bigger gap between adjacent pawl units by the free end, where there is more movement during use and where the bigger gap is beneficial to prevent tangling and / or friction between pawl units, while utilizing space closer to the fixed end better to achieve higher strength for given flexural performance of pawl members, where less movement of pawl members means that less spacing is needed between units.

[0050] In one embodiment of said freewheeling system for a bike, the said pawl members of said pawl part are configured to engage with said ratchet part, that has equally spaced ratcheting teeth, at different rotational locations, preferably equally spaced apart rotational locations, providing the freewheeling system with a high number of, preferably equally spaced apart, engagement points and thus a low angular distance between engagement points.

[0051] Thus, making said freewheeling system quick engaging while also ensuring that an engaged pawl member does not have to extend much before benefitting from load sharing with a subsequently engaging pawl member.

[0052] In one embodiment of said freewheeling system for a bike, the body of each of the said pawl members provides each of the said pawl members with a first stiffness indicative of stiffness of displacement of the free end along the radial direction to said common rotational axis and a second stiffness indicative of stiffness of displacement of the free end in parallel to said common rotational axis, wherein the second stiffness is greater than the first stiffness, for example greater by a factor of 2.0 or more, for example greater by a factor of 4.0 or more, such as greater by a factor of 8.0 or more.

[0053] Thus, making said pawl members able to easily slide over ratcheting teeth of said pawl part in the free rotational direction, while also being laterally stable and thus unlikely to get tangled with adjacent pawl units of said pawl part.

[0054] In one embodiment of said freewheeling system, said spring function of said pawl members in the circumferential direction around said common rotational axis allows up to 100% of the pawl members to engage under high torque being applied to the freewheeling system, despite the initial engagement points of said pawl members being different.

[0055] Thus, sharing the torque load between many, or all, pawl members, resulting in low loads per pawl member and thus high durability and longevity of said freewheeling system for a bike.

[0056] In one embodiment of said freewheeling system for a bike, said freewheeling system is a part of a bike hub providing a freewheeling function between the bike hub shell and the cassette of the bike; or said freewheeling system is a part of a bike cassette providing a freewheeling function between the cassette cogs and the bike hub; or said freewheeling system is at the interface between a bike hub and cassette providing a freewheeling function between the bike hub and the cassette of the bike.

[0057] Thus, said freewheeling system for a bike can either be built in a somewhat traditional manner where a standardized cassette is mounted to a freehub body of a hub comprising said freewheeling system for a bike, or the freewheeling system can be a part of a cassette that is then mounted to a hub, or the freewheeling function can take place at the connection between the cassette and hub where e.g. said cassette is comprising a ratcheting ring or said cassette is comprising a pawl part interacting with a hub that comprises the corresponding counterpart.

[0058] In one embodiment of said freewheeling system for a bike, a bike cassette, a bike rear hub shell, said ratchet part and said pawl part are separate bodies that are then attached together, for instance but not limited to via a freehub body.

[0059] In one embodiment of said freewheeling system for a bike, a bike cassette is construed to include said ratchet part as a part of its main structure, i.e. said ratchet part and the cassette being the one and same body.

[0060] In one embodiment of said freewheeling system for a bike, a bike cassette is construed to include said pawl part as a part of its main structure, i.e. said pawl part and the cassette being the one and same body.

[0061] In one embodiment of said freewheeling system for a bike, a bike rear hub shell of a bike rear hub is construed to include said ratchet part as a part of its main structure, i.e. said ratchet part and the hub shell being the one and same body.

[0062] In one embodiment of said freewheeling system for a bike, a rigid pawl structure is comprising said pawl part and cassette, said pawl part and cassette of said rigid pawl structure e.g. rigidly connected together by a freehub body, said pawl part of said rigid pawl structure extends into and interacts with said rear hub shell construed to include said ratchet part as a part of its main structure, said rigid pawl structure resting on a hub centre axle by a first pawl-structure-bearing located close to cassette-end of said hub and by a second pawl-structure-bearing spaced apart axially in a direction away from said cassette-end of said hub, while said hub shell is resting on said hub centre axle by a first hub-shell-bearing that is located close to hub’s distal axial end from said cassetteend and is resting on said rigid pawl structure by a second hub-shell-bearing that is located axially closer to the cassette-end of the hub than all the pawl members of said pawl part.

[0063] Thus, providing pawl members of said pawl part of said pawl structure access to ratchet teeth of said hub shell construed to include said ratchet part as a part of its main structure, while supporting said hub shell and said pawl structure on said centre axle with sufficient spacing between bearings to provide robust and reliable functionality, without the need for more bearings than 4.

[0064] In one embodiment of said freewheeling system for a bike, where a said pawl structure reaches into said hub shell, a third pawl-structure-bearing has been added to further support said pawl structure on said hub centre axle at a location further from said cassette-end than said second pawl-structure-bearing.

[0065] Thus, further supporting said pawl structure.

[0066] In one embodiment of said freewheeling system for a bike, a bike rear hub shell is construed to include said pawl part as a part of its main structure, i.e. said pawl part and the hub shell being the one and same body.

[0067] In one embodiment of said freewheeling system for a bike, a material of said pawl members is titanium or an alloy comprising at least 10 wt. % of titanium.

[0068] Thus, benefiting from titanium alloys’ excellent flexural fatigue performance, as well as titanium’s low weight to strength ratio.

[0069] In one embodiment of said freewheeling system for a bike, a material of said pawl members is steel or an alloy comprising at least 10 wt. % of steel.

[0070] Thus, benefiting from steel alloys’ excellent flexural fatigue performance and steel’s low cost.

[0071] In one embodiment of said freewheeling system for a bike, a material of said ratchet part is aluminium or an alloy comprising at least 10 wt. % of aluminium.

[0072] Thus, benefiting from aluminium alloys’ high strength to weight ratio, as well as low cost.

[0073] In one embodiment of said freewheeling system for a bike, a material of said ratchet part is steel or an alloy comprising at least 10 wt. % of steel.

[0074] Thus, benefiting from steel alloys’ high strength as well as low cost. In one embodiment of said freewheeling system for a bike, a material of said ratchet part is titanium or an alloy comprising at least 10 wt. % of titanium or an alloy comprising at least 10 wt. % of titanium.

[0075] Thus, benefiting from titanium alloys’ high strength to weight ratio.

[0076] In one embodiment of said freewheeling system for a bike, each of the said at least one pawl unit comprises at least 2 pawl members, for example at least 7 pawl members, such as at least 13 pawl members.

[0077] Thus, taking appropriately good advantage of the available circumferential space in the said freewheeling system, to distribute loads well while also achieving quick engagement.

[0078] In one embodiment of said freewheeling system for a bike, said ratchet part comprises, but is not limited to comprising, at least 10 teeth, for example at least 30 teeth, such as at least 60 teeth.

[0079] Thus, taking good advantage of the available circumferential space in the said freewheeling system, to distribute loads well while also achieving quick engagement.

[0080] In one embodiment of said freewheeling system for a bike, said ratchet part comprises n equal and equally spaced apart ratcheting teeth, wherein each of the said at least one pawl unit comprises N equal and equally spaced apart pawl members, wherein N x p + 2 = n where p is an integer and N is an odd integer 5 or larger, such as 5, 7, 9, 11 , 13, 15 or 17.

[0081] Thus, resulting in a freewheeling system for a bike where:

[0082] 1. The 1stpawl member of said at least one pawl unit is defined to engage at 0°,

[0083] 2. The 2ndpawl member of said at least one pawl unit engages at the next engagement point in said direction C from the 180° offset point from the 1stpawl member to engage, thus balancing the load effectively on the freewheeling system,

[0084] 3. The 3rdpawl member of said at least one pawl unit to engage is next to the 1stpawl member to engage, next to it in the circumferential direction C, thus being pulled away from colliding with the 1stpawl member to engage as it extends towards the 3rdpawl member to engage,

[0085] 4. The 4thpawl member of said at least one pawl unit to engage is next to the 2ndpawl member to engage, next to it in the circumferential direction C, thus being pulled away from colliding with the 2ndpawl member to engage as it extends towards the 4thpawl member to engage. Thus re-balancing the load effectively on the freewheeling system,

[0086] 5. Etc...until up to N of the pawl members of said at least one pawl unit have engaged.

[0087] Thus, loading said at least one pawl unit with excellent load balance and load distribution while also preventing pawl members from colliding with adjacent pawl members, of same pawl unit, when extended under load. In one embodiment of said freewheeling system for a bike, each of the teeth of the ratchet unit is asymmetrical, with a steeper slope or a hook shape on the side configured to engage with hook-shaped free ends of said pawl members, and a lesser slope on the side configured to allow slide of said hook-shaped free ends of said pawl members.

[0088] Thus, providing engagement of hook-shaped free ends in one rotational direction and providing an easy slide of hook-shaped free ends over ratcheting teeth in the opposite rotational direction.

[0089] In one embodiment, said freewheeling system is a double freewheeling system, comprising

[0090] • a first freewheeling system, comprising a first pawl part and a first ratchet part, according to any of the preceding embodiments, and

[0091] • a second freewheeling system, comprising a second pawl part and a second ratchet part, according to any of the preceding claims, the common rotational axis of the first freewheeling system being the same as the common rotational axis of the second freewheeling system, the radial direction of the second freewheeling system being opposite to the radial direction R of the said first freewheeling system, wherein said first ratchet part and said second ratchet part are rigidly connected and thus form a double ratchet part having a radial gap between the teeth of the first ratchet part and the teeth of the second ratchet part, and wherein said first pawl part and said second pawl part are rigidly connected and thus form a double pawl part being positioned in the radial gap of the double ratchet part, the fixed ends of pawl members of the double pawl part sharing the same support structure at the fixed ends of said pawl members.

[0092] Thus, for a given freewheeling system performance level, more optimally using support material of said pawl part, and more optimally using laterally space within the hub shell, resulting in a lighter and more compact system.

[0093] In one embodiment of the said double freewheeling system, the double freewheeling system comprises: a hub centre axle; a double rigid pawl structure, the double rigid pawl structure comprising said double pawl part and a cassette, said double pawl part and said cassette rigidly connected together by a freehub body, said double rigid pawl structure resting on said hub centre axle by a first double-pawl-structure-bearing located at a cassette-end of said hub centre axle and by a second double-pawl-structure-bearing spaced apart axially in a direction away from said cassette-end; and a rear hub shell, the rear hub shell comprising said double ratchet part, said hub shell resting on said hub centre axle by a first hub-shell-bearing located at a distal axial end of the hub centre axle relative to said cassette-end and resting on said hub centre axle by a second hub-shell-bearing located between the first hub-shell-bearing and said second double-pawl-structure-bearing.

[0094] Thus, locating said bearings at convenient locations, and facilitating the use of 4 same-size bearings for the complete hub.

[0095] In one embodiment of said freewheeling system for a bike, said freewheeling system is a part of an e-bike bottom bracket located electric motor and crankset assembly, and thus provides freewheeling between said e- bike motor and said crankset of said e-bike.

[0096] Thus, allowing the rider to pedal freely when the e-bike motor is not providing power.

[0097] In one embodiment of said freewheeling system for a bike, a method of operating said freewheeling system wherein frequently during normal use of said bike 4 or more of the pawl members of said pawl part engage sequentially with teeth of said ratchet part as more and more torque is applied to said freewheeling system in the torque-transmitting rotational direction, as the bodies of engaged pawl members extend under said applied torque enabling engagement of subsequent pawl members.

[0098] Thus, enabling a freewheeling mechanism that engages quickly, smoothly / gradually and is also able to reliably deal with high input torque by distributing load on several pawl members.

[0099] According to a second aspect, the present invention relates to a bike comprising said freewheeling system, where said bike can be a pedal powered bike or an electrically assisted e-bike.

[0100] Throughout this document it is assumed that the bike, including said freewheeling system for a bike, is unless otherwise specified in an upright position with both front and rear wheels resting on horizontal ground with the rotational axis of the wheels parallel to the ground.

[0101] In general, the various aspects of the invention may be combined and coupled in any way possible within the scope of the invention. These and other aspects, features and / or advantages of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter. BRIEF DESCRIPTION OF DRAWINGS

[0102] FIGs 1-12 show different embodiments of said freewheeling system for a bike according to the present invention.

[0103] FIG 13 shows a system drawing of some different possible locations of said freewheeling system within the drivetrain of a bike. FIGs 14-20 show different more detailed embodiments of said freewheeling system, where said ratchet part is a part of the hub shell body.

[0104] FIGs 21 and 22 show embodiments of said freewheeling system, where one or more of said pawl members are of a lengthwise split design.

[0105] DESCRIPTION OF EMBODIMENTS

[0106] The present invention relates to an improved freewheeling system for bikes. In particular, one that offers an appealing combination of simplicity, lightweight, quick engagement, smooth engagement, low friction, durability, and robust / reliable bike freewheeling operation.

[0107] FIG 1 shows a freewheeling system (101) for a bike, the freewheeling system comprising a circular ratchet part (102) and a circular pawl part (103) with a common rotational axis (104), said circular ratchet part comprising teeth (105) circularly disposed on the ratchet part; and said circular pawl part comprising at least one circular pawl unit (106), each of the at least one circular pawl unit comprising pawl members (107) circularly disposed, each of the pawl members comprising a body having a fixed end (108) and a hook-shaped free end (109), as viewed in a direction parallel to said common rotational axis, distal to the fixed end, wherein the fixed end is attached to the rest of the pawl part, wherein the hook-shape of the free end is arranged to engage with the teeth of the ratchet part, wherein each of the at least one circular pawl unit has all its pawl members extending from their respective fixed ends to their respective hook-shaped free ends along a mutual plane that is perpendicular to the said common rotational axis, wherein each of the pawl members of said pawl part extend from its fixed end to its hook-shaped free end in a direction consisting of a radial component R to the said common rotational axis and a circumferential component C around the said common rotational axis, wherein the teeth of the said ratchet unit extend as far or further in both opposite directions parallel to the said common rotational axis than the hook-shaped free ends of all the pawl members of said pawl part, wherein each of the pawl members is arranged to be under a radial pre-load by pushing against said ratchet part along the said radial direction R, wherein each of the pawl members has an engaged configuration and a disengaged configuration relative to the teeth of the ratchet part, wherein the engaged configuration of said each of the pawl members has its said hookshaped free end hooking onto at least one of the teeth of the said ratchet part, thereby loading that said each of the pawl members in tension when said freewheeling system for a bike is transmitting applied torque, and thus said each of the pawl members resisting relative rotation between said ratchet part and said pawl part around said common rotational axis, wherein at least a portion of the body of each of the said pawl members is a spring such that said each of the pawl members is arranged to be adjusted from the engaged configuration to the disengaged configuration upon relative rotation between said ratchet part and said pawl part in the free relative rotational direction around said common rotational axis, that is opposite to the said resisted torque transmitting relative rotation between said ratchet part and said pawl part, by the spring portion of the body of the said each of the pawl members bending against the radial direction R to displace its hook-shaped free end as it slips over ratcheting teeth of the said ratchet part.

[0108] Thus, providing a freewheeling system for a bike that is simple in construction, has no supplemental components or pivots to its pawl member engagement functionality, requires little or no maintenance beyond the potential occasional lubrication, and can be made lightweight, quickly engaging, smoothly engaging and robust / reliable.

[0109] FIG 2 shows an isometric view of the embodiment from FIG 1 , albeit with ten pawl members instead of 13 and 60 ratcheting teeth instead of 67.

[0110] FIG 3 shows an isometric view of a variation of the embodiment from FIG 2, where its pawl part now comprises two pawl units (106a and 106b) instead of one pawl unit.

[0111] The first pawl unit 106a of the two pawl units corresponds to the pawl unit of the embodiment illustrated in FIG 2. In addition, the embodiment illustrated in FIG 3 comprises a second pawl unit 106b offset from the first pawl unit 106a along the common rotational axis.

[0112] Each pawl unit 106a, 106b comprises circularly disposed pawl members. The pawl members of the first pawl unit 106a of the two pawl units are rotationally shifted around the common rotational axis relative to the pawl members of the second pawl unit 106b of the two pawl units.

[0113] FIG 4 shows a view in the direction of said common rotational axis on the embodiment from FIG 3, the two pawl units (106a and 106b) each having ten pawl members now appearing, from this point of view, to have a silhouette similar to a single pawl unit with 20 pawl members.

[0114] FIG 5a shows one embodiment where said radial direction R is inwards towards the said common rotational axis, thus the radius of said pawl part being larger than the radius of said ratchet part, FIG 5b shows the same embodiment in an isometric view. While FIGs 1-4, described above, show embodiments of said freewheeling system for a bike where said radial direction R is outwards from the said common rotational axis, thus the radius of said ratchet part being larger than the radius of said pawl part.

[0115] Thus, when R is outwards said ratchet part has a larger radius and can thus have more ratcheting teeth around its circumference and said pawl units of said pawl part has more space for its hook-shaped free ends, pushing up against said ratchet part, furthermore for R being outwards, if said pawl members are designed to have substantial circumferential tension spring-function, then the said hook-shaped free ends can grab more and more loosely onto ratcheting teeth as the relative engaged rotation between pawl part and ratchet part makes the grab angle of ratcheting teeth slacker as the relative rotation progresses, potentially providing an overload protection function for said pawl members. When R is inwards, the pawl part has a larger radius and thus the pawl units of the pawl part have more space for fixed ends of its pawl members, furthermore for R being inwards, if said pawl members are designed to have substantial circumferential tension spring-function, then the said hook-shaped free ends can grab more and more securely onto ratcheting teeth as the relative engaged rotation between pawl part and ratchet part makes the grab angle of ratcheting teeth sharper as the relative rotation progresses.

[0116] In one embodiment of said freewheeling system for a bike, the body of each of one or more of said pawl members has a tension spring-function in the circumferential direction around said common rotational axis derived from said body having a non-linear extension, as viewed in a direction parallel to said common rotational axis, from the fixed end to the hook-shaped free end.

[0117] Thus, enabling said pawl member to extend under torque being applied to the said freewheeling system and thus engaging smoothly and allowing one or more other pawl members, with a different rotational engagement location, to also engage and thus spread the load and allow a gradual smooth engagement of said freewheeling system.

[0118] FIG 6a shows one embodiment of said freewheeling system for a bike (101), where the body of each of one or more of said pawl members (107) has a tension spring-function in the circumferential direction around said common rotational axis. The embodiment shown here has 13 equal equally spaced apart pawl members and 67 equal equally spaced apart ratchet teeth. In the illustrated embodiment, the pawl members have a spatial curvature from the fixed end to the free end. This spatial curvature provides the individual pawl member with a tension spring-function in the circumferential direction. At the fixed end, the extension of the body of the pawl members is initially primarily in the circumferential direction, and along the body of the pawl members, the extension gradually changes direction towards the radial direction. FIG 6b shows a detail view of one pawl member (107) of another embodiment in which the pawl members have a spatial curvature from the fixed end to the free end. At the fixed end, the extension of the body of the pawl members is initially primarily in the radial direction, and along the body of the pawl members, the extension gradually changes direction towards the circumferential direction.

[0119] FIG 7 shows the embodiment from FIG 6a during use where a first pawl member (701), then a second pawl member (702), and then a third pawl member (703) have been stretched by applied torque through said freewheeling system and the fourth pawl member (704) has just engaged, where said fourth pawl member would also become stretched if more torque would be applied, if more torque was applied a fifth pawl member (705) would engage next and thereafter a sixth pawl member (706), etc. as long as previously engaged pawl members are able to extend far enough to facilitate.

[0120] Thus, enabling said pawl member to extend under torque being applied to the said freewheeling system and thus engaging smoothly and allowing one or more other pawl members, with a different rotational engagement location, to also engage and thus spread the load and allow a gradual smooth engagement of said freewheeling system.

[0121] In one embodiment of said freewheeling system for a bike, the body of each of one or more of said pawl members has a tension spring-function in the circumferential direction around said common rotational axis derived from said body extending from the fixed end to the hook-shaped free end in a wave shaped manner, where the radial component of the extension direction alternates one or more times between the opposite radial directions relative to said common rotational axis.

[0122] Thus, enabling said pawl member to extend under torque being applied to the said freewheeling system and thus engaging smoothly and allowing one or more other pawl members, with a different rotational engagement location, to also engage and thus spread the load and allow a gradual smooth engagement of said freewheeling system. Said wave shape offering the benefit of stiffness and strength of said pawl member in the circumferential direction ramping up as said pawl member extends, as the wave shape become shallower with the extension and thus the bending moment on the extremities of the wave shape of said pawl members lessens.

[0123] FIG 8a shows an embodiment of said freewheeling system 101 for a bike, where the body of each of one or more of said pawl members has a tension spring-function in the circumferential direction around said common rotational axis derived from said body extending from the fixed end to the hook-shaped free end in a wave shaped manner, where the radial component of the extension direction alternates 2 or more times, 5 times shown here, between the opposite radial directions relative to said common rotational axis. The figure shows a variant of the described embodiment that has 5 equal and equally spaced apart pawl members and 67 equal and equally spaced apart ratchet teeth.

[0124] FIG 8b shows the embodiment from FIG8a where torque has been applied through the freewheeling system so that, measured from initial engagement of the first pawl member to engage (801), there has occurred relative rotation between said pawl part and said ratchet part of 1 / n * 360°, where n is the number of ratcheting teeth of the ratchet part, so that the first 801 , second 802, third 803, fourth 804 and fifth 805 pawl members have been engaged.

[0125] Thus, enabling said pawl member to extend under torque being applied to the said freewheeling system and thus engaging smoothly and allowing one or more other pawl members, with a different rotational engagement location, to also engage and thus spread the load and allow a gradual smooth engagement of said freewheeling system. Said wave shape offering the benefit of stiffness and strength of said pawl member in the circumferential direction ramping up as said pawl member extends, as the wave shape become shallower with the extension and thus the bending moment on the extremities of the wave shape of said pawl members lessens. Having multiple waves in the wave shape gives further circumferential spring-function.

[0126] FIG 9a shows a detail view of one embodiment of said freewheeling system for a bike, where each of the said pawl members (107) have an overload protection function derived from a substantial portion of its pawl member body being located far enough in a direction opposite to said radial direction R from a straight line drawn (901) from the center of the fixed end of said each of the said pawl members to its hook-shaped free end’s engagement point to said ratchet part, such that the bending of said each of the said pawl members under extreme torque transmitting loads results in a twist of its hook-shaped end so it slips out and unhooks from engagement.

[0127] FIG 9b shows a detail view of the embodiment from FIG9a where the pictured pawl member has slipped out of engagement, from an extreme torque load.

[0128] Thus, said overload protection functionality saving / protecting said each of the said pawl members in potential cases where said freewheeling system is designed to share torque load on multiple pawl members but something, such as part construction inaccuracy or some wear or debris hindering optimal functionality, caused the freewheeling system to have fewer than planned / designed for co-acting engagements. Then this overload protection allows the freewheeling system to progress beyond the partially failed engagement and onto the next subsequent engagement point in its rotation, where pawl members should be safely ready for engagement.

[0129] FIG 10 shows a detailed view of an embodiment of said freewheeling system for a bike, where one or more of said pawl members (107) comprise two or more hook-shapes on their distal free end.

[0130] Thus, spreading load of said one or more pawl members on more ratchet teeth and more hook ends.

[0131] FIG 11 shows one embodiment of said freewheeling system for a bike, where each of the pawl members of said pawl part extend from its fixed end to its hook-shaped free end in said radial direction R a distance of 2-30mm, such as 5-16mm, and in direction C circumferential around the common rotational axis a distance of 10-60mm, such as 15-40mm, and the thickness of each of the pawl members of said pawl part measured in the direction of said common rotational axis, into the picture as viewed in FIG11 , is 1-80mm, such as 2-20mm, and the width w of the body of each of said pawl members of said pawl part measured perpendicularly to its extension direction from fixed end to hook-shaped end is, as viewed in a direction parallel to said common rotational axis, 0.2- 10mm, such as 1-5mm, and the radius Rt from the said common rotational axis to the tips of said teeth of said ratchet part is 10-80mm, such as 20-50mm. Thus, being appropriately sized to fit on bikes without excess bulkiness and appropriately sized to also be able to deal with the loads present.

[0132] In one embodiment of said freewheeling system for a bike, said pawl part comprises at least two pawl units wherein each of the said at least two pawl units are offset from each other along said common rotational axis such that there are up to 20mm, such as up to 5mm, between adjacent said at least two pawl units measured parallel to said common rotational axis.

[0133] Thus, spreading loads on more pawl members of more pawl units within its pawl part, resulting in a freewheeling system for a bike that is quicker engaging and is also more robust to occasional failure of individual pawl members to engage. If said freewheeling system for a bike is designed to have a very high number of lightly- acting co-acting pawl members under high pedaling torque, such as 10-100 or more pawl members, then it becomes mechanically acceptable if pawl members occasionally fail to engage as there are so many others making up for it, which subsequently means that said pawl members can be designed to have a lighter radial push on said ratchet part, as they don’t need to be guaranteed to always engage safely, this consequently means that said freewheeling system for a bike can have lower freewheeling friction, less wear, and more silent operation.

[0134] FIG 12 shows a view parallel to said common rotational axis of one embodiment of said freewheeling system for a bike, where said pawl part comprises 3-50 pawl units, such as 4-18 pawl units, 3 units shown in figure (1201a, 1201 b, 1201c), wherein each of the pawl units are offset from each other along said common rotational axis such that there are up to 20mm between adjacent pawl units measured parallel to said common rotational axis.

[0135] In one embodiment of said freewheeling system for a bike, all said fixed ends of all pawl members are rigidly connected to one another via the central portion of said pawl part.

[0136] Thus, spinning together with constant relative dimensions of all said fixed ends of all pawl members, of all of its one or more pawl units, towards each other.

[0137] In one embodiment of said freewheeling system for a bike, said pawl part is formed as a single continuous body that is rigid between all said fixed ends of all said pawl members.

[0138] Thus, spinning together with constant relative dimensions of all said fixed ends of all pawl members, of all of its one or more pawl units, towards each other and simultaneously limiting excess weight, bulkiness, material transition areas prone to failure, and assembly complexity.

[0139] In one embodiment of said freewheeling system for a bike, manufacturing of said pawl part comprises additive manufacturing, such as 3d printing. Thus, enabling economical and high-quality construction of a pawl part having multiple pawl units without any assembly or joining of parts being required, thus enabling a lightweight and compact pawl part with multiple pawl units.

[0140] In one embodiment of said freewheeling system for a bike, one or more of said pawl members have a varying thickness measured in the direction parallel to said common rotational axis, where said thickness is greater closer to the fixed end and lesser closer to the hook-shaped free end.

[0141] Thus, creating a bigger gap between adjacent pawl units by the free end, where there is more movement during use and where the bigger gap is beneficial to prevent tangling and / or friction between pawl units, while utilizing space closer to the fixed end better to achieve higher strength for given flexural performance of pawl members, where less movement of pawl members means that less spacing is needed between units.

[0142] In one embodiment of said freewheeling system for a bike, the said pawl members of said pawl part are configured to engage with said ratchet part, that has equally spaced ratcheting teeth, at different rotational locations, preferably equally spaced apart rotational locations, providing the freewheeling system with a high number of, preferably equally spaced apart, engagement points and thus a low angular distance between engagement points.

[0143] Thus, making said freewheeling system quick engaging while also ensuring that an engaged pawl member does not have to extend much before benefitting from load sharing with a subsequently engaging pawl member.

[0144] In one embodiment of said freewheeling system for a bike, the body of each of the said pawl members provides each of the said pawl members with a first stiffness indicative of stiffness of displacement of the free end along the radial direction to said common rotational axis and a second stiffness indicative of stiffness of displacement of the free end in parallel to said common rotational axis, wherein the second stiffness is greater than the first stiffness, for example greater by a factor of 2.0 or more, for example greater by a factor of 4.0 or more, such as greater by a factor of 8.0 or more.

[0145] Thus, making said pawl members able to easily slide over ratcheting teeth of said pawl part in the free rotational direction, while also being laterally stable and thus unlikely to get tangled with adjacent pawl units of said pawl part.

[0146] In one embodiment of said freewheeling system, said spring function of said pawl members in the circumferential direction around said common rotational axis allows up to 100% of the pawl members to engage under high torque being applied to the freewheeling system, despite the initial engagement points of said pawl members being different. Thus, sharing the torque load between many, or all, pawl members, resulting in low loads per pawl member and thus high durability and longevity of said freewheeling system for a bike.

[0147] In one embodiment of said freewheeling system for a bike, said freewheeling system is a part of a bike hub providing a freewheeling function between the bike hub shell and the cassette of the bike; or said freewheeling system is a part of a bike cassette providing a freewheeling function between the cassette cogs and the bike hub; or said freewheeling system is at the interface between a bike hub and cassette providing a freewheeling function between the bike hub and the cassette of the bike.

[0148] FIG 13 shows three different embodiments (1301 a, 1301 b, 1301c) schematically illustrating how said freewheeling system for a bike (FWS) can be located on the path of input power P towards the ground.

[0149] Thus, said freewheeling system for a bike can either be built in a somewhat traditional manner where a standardized cassette is mounted to a freehub body of a hub comprising said freewheeling system for a bike, or the freewheeling system can be a part of a cassette that is then mounted to a hub, or the freewheeling function can take place at the connection between the cassette and hub where e.g. said cassette is comprising a ratcheting ring or said cassette is comprising a pawl part interacting with a hub that comprises the corresponding counterpart.

[0150] In one embodiment of said freewheeling system for a bike, a bike cassette, a bike rear hub shell, said ratchet part and said pawl part are separate bodies that are then attached together, for instance but not limited to via a freehub body.

[0151] In one embodiment of said freewheeling system for a bike, a bike cassette is construed to include said ratchet part as a part of its main structure, i.e. said ratchet part and the cassette being the one and same body.

[0152] In one embodiment of said freewheeling system for a bike, a bike cassette is construed to include said pawl part as a part of its main structure, i.e. said pawl part and the cassette being the one and same body.

[0153] FIG 14 shows one embodiment of said freewheeling system for a bike, where a bike rear hub shell (1401) of a bike rear hub is construed to include said ratchet part as a part of its main structure, with said ratchet teeth (1402) being a part of the internal shape of said hub shell, i.e. said ratchet part and the hub shell being the one and same body. In this figure only the hub shell and the centre axle (1403) of said bike rear hub are shown. Spokes of a built bike rear wheel would attach to spoke flanges (1404) of said rear hub shell and brake rotor would attach to brake rotor mount (1405) of said rear hub shell. Other parts such as bearings, seals, freehub, etc are omitted for simplicity. Thus, saving weight that a separate ratchet part would require, as well as providing a significant amount of space available within said bike hub shell for multiple pawl units of said pawl part.

[0154] FIG 15 shows one embodiment of said freewheeling system for a bike, where a rigid pawl structure is comprising firstly a said pawl part (1501) comprising two or more said pawl units (1502), 19 pawl units shown here, and secondly a cassette (1503), said pawl part and cassette of said rigid pawl structure e.g. rigidly connected together by a freehub body (1504) that is rigidly connected to both said cassette and said pawl part through any applicable fastening method such as threaded together, bolted together, bonded together, welded together, etc., or said freehub body can be included in the body of either or both of said cassette and said pawl part, said pawl part of said rigid pawl structure extends into and interacts with said rear hub shell construed to include said ratchet part as a part of its main structure, said rigid pawl structure resting on a hub centre axle by a first pawl- structure-bearing (1505) located close to cassette-end of said hub and by a second pawl-structure-bearing (1506) spaced apart axially in a direction away from said cassette-end of said hub, while said hub shell is resting on said hub centre axle by a first hub-shell-bearing (1507) that is located close to hub’s distal axial end from said cassette-end and is resting on said rigid pawl structure by a second hub-shell-bearing (1508) that is located axially closer to the cassette-end of the hub than all the pawl members of said pawl part. Details such as seals are omitted in this figure for simplicity.

[0155] Thus, providing pawl members of said pawl part of said pawl structure access to ratchet teeth of said hub shell construed to include said ratchet part as a part of its main structure, while supporting said hub shell and said pawl structure on said centre axle with sufficient spacing between bearings to provide robust and reliable functionality, without the need for more bearings than 4.

[0156] FIG 16 shows one embodiment of said freewheeling system for a bike from FIG15 where a third pawl-structure- bearing (1601) has been added to further support said pawl structure on said hub centre axle at a location further from said cassette-end than said second pawl-structure-bearing.

[0157] Thus, further supporting said pawl-structure.

[0158] FIG 17 shows an embodiment of said freewheeling system for a bike from FIG15, where the detail location of said second pawl-structure-bearing (1701) has been altered within the scope of the description of FIG15. Said second pawl-structure-bearing now resting up against said pawl part instead of said freehub body of said rigid pawl structure, with similar end result as pawl part and freehub body are both a part of the same rigid pawl structure.

[0159] FIG 18 shows an embodiment of said freewheeling system for a bike from FIG15, where the detail locations of said second pawl-structure-bearing (1801) and the second hub-shell-bearing (1802) have been altered within the scope of the description of FIG15. FIG 19 shows an embodiment of said freewheeling system for a bike from FIG15, where the hub shell and pawl part dimensions have been altered to accommodate pawl units (1901) with a larger diameter than in FIG 15, the embodiment on FIG 19 also has its pawl unit shorter than the one shown on FIG 15.

[0160] In one embodiment of said freewheeling system for a bike, a bike rear hub shell is construed to include said pawl part as a part of its main structure, i.e. said pawl part and the hub shell being the one and same body.

[0161] In one embodiment of said freewheeling system for a bike, said freewheeling system is a part of an e-bike bottom bracket located electric motor and crankset assembly, and thus provides freewheeling between said e- bike motor and said crankset of said e-bike.

[0162] Thus, allowing the rider to pedal freely when the e-bike motor is not providing power.

[0163] In one embodiment of said freewheeling system for a bike, a material of said pawl members is titanium or an alloy comprising at least 10 wt. % of titanium.

[0164] Thus, benefiting from titanium alloys’ excellent flexural fatigue performance, as well as titanium’s low weight to strength ratio.

[0165] In one embodiment of said freewheeling system for a bike, a material of said pawl members is steel or an alloy comprising at least 10 wt. % of steel.

[0166] Thus, benefiting from steel alloys’ excellent flexural fatigue performance and steel’s low cost.

[0167] In one embodiment of said freewheeling system for a bike, a material of said ratchet part is aluminium or an alloy comprising at least 10 wt. % of aluminium.

[0168] Thus, benefiting from aluminium alloys’ high strength to weight ratio, as well as low cost.

[0169] In one embodiment of said freewheeling system for a bike, a material of said ratchet part is steel or an alloy comprising at least 10 wt. % of steel.

[0170] Thus, benefiting from steel alloys’ high strength as well as low cost.

[0171] In one embodiment of said freewheeling system for a bike, a material of said ratchet part is titanium or an alloy comprising at least 10 wt. % of titanium or an alloy comprising at least 10 wt. % of titanium.

[0172] Thus, benefiting from titanium alloys’ high strength to weight ratio. In one embodiment of said freewheeling system for a bike, each of the said at least one pawl unit comprises at least 2 pawl members, for example at least 7 pawl members, such as at least 13 pawl members.

[0173] Thus, taking appropriately good advantage of the available circumferential space in the said freewheeling system, to distribute loads well while also achieving quick engagement.

[0174] In one embodiment of said freewheeling system for a bike, said ratchet part comprises, but is not limited to comprising, at least 10 teeth, for example at least 30 teeth, such as at least 60 teeth.

[0175] Thus, taking good advantage of the available circumferential space in the said freewheeling system, to distribute loads well while also achieving quick engagement.

[0176] In one embodiment of said freewheeling system for a bike, said ratchet part comprises n equal and equally spaced apart ratcheting teeth, wherein each of the said at least one pawl unit comprises N equal and equally spaced apart pawl members, wherein N x p + 2 = n where p is an integer and N is an odd integer 5 or larger, such as 5, 7, 9, 11 , 13, 15 or 17.

[0177] Thus, resulting in a freewheeling system for a bike where:

[0178] 1. The 1stpawl member of said at least one pawl unit is defined to engage at 0°,

[0179] 2. The 2ndpawl member of said at least one pawl unit engages at the next engagement point in said direction C from the 180° offset point from the 1stpawl member to engage, thus balancing the load effectively on the freewheeling system,

[0180] 3. The 3rdpawl member of said at least one pawl unit to engage is next to the 1stpawl member to engage, next to it in the circumferential direction C, thus being pulled away from colliding with the 1stpawl member to engage as it extends towards the 3rdpawl member to engage,

[0181] 4. The 4thpawl member of said at least one pawl unit to engage is next to the 2ndpawl member to engage, next to it in the circumferential direction C, thus being pulled away from colliding with the 2ndpawl member to engage as it extends towards the 4thpawl member to engage. Thus re-balancing the load effectively on the freewheeling system,

[0182] 5. Etc...until up to N of the pawl members of said at least one pawl unit have engaged.

[0183] Thus, loading said at least one pawl unit with excellent load balance and load distribution while also preventing pawl members from colliding with adjacent pawl members, of same pawl unit, when extended under load.

[0184] In one embodiment of said freewheeling system for a bike, each of the teeth of the ratchet unit is asymmetrical, with a steeper slope or a hook shape on the side configured to engage with hook-shaped free ends of said pawl members, and a lesser slope on the side configured to allow slide of said hook-shaped free ends of said pawl members. Thus, providing engagement of hook-shaped free ends in one rotational direction and providing an easy slide of hook-shaped free ends over ratcheting teeth in the opposite rotational direction.

[0185] In one embodiment, said freewheeling system is a double freewheeling system, comprising a

[0186] • a first freewheeling system, comprising a first pawl part and a first ratchet part, according to any of the preceding embodiments, and

[0187] • a second freewheeling system, comprising a second pawl part and a second ratchet part, according to any of the preceding claims, the common rotational axis of the first freewheeling system being the same as the common rotational axis of the second freewheeling system, the radial direction of the second freewheeling system being opposite to the radial direction R of the said first freewheeling system, wherein said first ratchet part and said second ratchet part are rigidly connected and thus form a double ratchet part having a radial gap between the teeth of the first ratchet part and the teeth of the second ratchet part, and wherein said first pawl part and said second pawl part are rigidly connected and thus form a double pawl part being positioned in the radial gap of the double ratchet part, the fixed ends of pawl members of the double pawl part sharing the same support structure at the fixed ends of said pawl members.

[0188] Thus, for a given freewheeling system performance level, more optimally using support material of said pawl part, and more optimally using laterally space within the hub shell, resulting in a lighter and more compact system.

[0189] FIG 20 shows an embodiment of the said double freewheeling system, where the a double rigid pawl structure comprises said double pawl part (2001), with the pawl members (2002) belonging to the first pawl part of said double pawl part here shown with R outwards and the pawl members (2003) belonging to the second pawl part of said double pawl part here shown with R inwards, and a cassette, said double pawl part and cassette of said double rigid pawl structure e.g. rigidly connected together by a freehub body (2004) that is here shown to be the same body as said double pawl part. Said double pawl part of said double rigid pawl structure extends into and interacts with a rear hub shell comprising said double ratchet part (2005) as a part of its main structure. Said double rigid pawl structure rests on a hub centre axle by a first double-pawl-structure-bearing (2006) located close to a cassette-end of said hub centre axle and by a second double-pawl-structure-bearing (2007) spaced apart axially in a direction away from said cassette-end of said hub centre axel. Said rear hub shell rests on said hub centre axle by a first hub-shell-bearing (2008) located close to hub’s distal axial end relative to said cassette-end and rests on said hub centre axle by a second hub-shell-bearing (2009) that is located axially closer to the cassette-end of the hub, yet still further away from the cassette-end of the hub than the said second double-pawl-structure-bearing. Thus, locating said bearings at convenient locations, and facilitating the use of 4 same-size bearings for the complete hub.

[0190] FIG 21 shows a detail view of an embodiment of said freewheeling system for a bike, where one or more of said pawl members each comprises at least one slit or gap providing an opening in a direction parallel to said common rotational axis and extending in a lengthwise direction between the free end and the fixed end such that a material thickness of the pawl member transverse to said lengthwise direction on each side of the pawl member is substantially similar. Such an implementation of a pawl member can also be referred to as a lengthwise split design. In this figure, there is one lengthwise slit, or gap, thereby efficiently provided two parallel springs.

[0191] Thus, by making said one or more pawl members effectively constructed of two or more substantially parallel springs, a pawl member can be made significantly more flexible to applied bending moment loads while maintaining a given tension strength. This, in turn, can make said freewheeling system substantially more forgiving towards sudden input loads and furthermore enable it to more efficiently spread loads between its multiple pawl members.

[0192] FIG 22 shows a variation of the embodiment of FIG 21 where now there are two slits, or gaps, (2201). These two slits extend parallelly to each other, thereby efficiently provided three parallel springs.

[0193] In one embodiment of said freewheeling system for a bike, a method of operating said freewheeling system wherein frequently during normal use of said bike 4 or more of the pawl members of said pawl part engage sequentially with teeth of said ratchet part as more and more torque is applied to said freewheeling system in the torque-transmitting rotational direction, as the bodies of engaged pawl members extend under said applied torque enabling engagement of subsequent pawl members.

[0194] Thus, enabling a freewheeling mechanism that engages quickly, smoothly / gradually and is also able to reliably deal with high input torque by distributing load on several pawl members.

[0195] While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive; the invention is not limited to the disclosed embodiments. Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. Any reference signs in the claims should not be construed as limiting the scope.

Claims

CLAIMS1. A freewheeling system (101) for a bike, the freewheeling system comprising a circular ratchet part (102) and a circular pawl part (103) with a common rotational axis (104), said circular ratchet part comprising teeth (105) circularly disposed on the ratchet part; and said circular pawl part comprising at least one circular pawl unit (106), each of the at least one circular pawl unit comprising pawl members (107) circularly disposed, each of the pawl members comprising a body having a fixed end (108) and a hook-shaped free end (109), as viewed in a direction parallel to said common rotational axis, distal to the fixed end, wherein the fixed end is attached to the rest of the pawl part, wherein the hook-shape of the free end is arranged to engage with the teeth of the ratchet part, wherein each of the at least one circular pawl unit has all its pawl members extending from their respective fixed ends to their respective hook-shaped free ends along a mutual plane that is perpendicular to the said common rotational axis, wherein each of the pawl members of said pawl part extend from its fixed end to its hook-shaped free end in a direction consisting of a radial component R to the said common rotational axis and a circumferential component C around the said common rotational axis, wherein the teeth of the said ratchet unit extend as far or further in both opposite directions parallel to the said common rotational axis than the hook-shaped free ends of all the pawl members of said pawl part, wherein each of the pawl members is arranged to be under a radial pre-load by pushing against said ratchet part along the said radial direction R, wherein each of the pawl members has an engaged configuration and a disengaged configuration relative to the teeth of the ratchet part, wherein the engaged configuration of said each of the pawl members has its said hookshaped free end hooking onto at least one of the teeth of the said ratchet part, thereby loading that said each of the pawl members in tension when said freewheeling system for a bike is transmitting applied torque, and thus said each of the pawl members resisting relative rotation between said ratchet part and said pawl part around said common rotational axis, wherein at least a portion of the body of each of the said pawl members is a spring such that said each of the pawl members is arranged to be adjusted from the engaged configuration to the disengaged configuration upon relative rotation between said ratchet part and said pawl part in the free relative rotational direction around said common rotational axis, that is opposite to the said resisted torque transmitting relative rotation between said ratchet part and said pawl part, by the spring portion of the body of the said each of the pawl members bendingagainst the radial direction R to displace its hook-shaped free end as it slips over ratcheting teeth of the said ratchet part.

2. The freewheeling system according to claim 1 , the spring of the body of each of the pawl members has a tension spring component to circumferentially displace the free end from the fixed end upon transmitting applied torque between the ratchet part and the pawl part.

3. The freewheeling system according to claim 2, wherein the tension spring component of each of the pawl members is provided by any of:- the body of said each of the pawl members extending from the fixed end to the hook-shaped free end in a direction that gradually goes from a more circumferential direction to a more radial direction or goes from a more radial direction to a more circumferential direction, relative to said common rotational axis;- the body of said each of the pawl members extending from the fixed end to the hook-shaped free end in a wave shaped manner, where the radial component of the extension direction alternates one or more times between the opposite radial directions relative to said common rotational axis; and- the body of said each of the pawl members extending from the fixed end to the hook-shaped free end in a wave shaped manner, where the radial component of the extension direction alternates two or more times between the opposite radial directions relative to said common rotational axis.

4. The freewheeling system according to any of claims 2-3, wherein the pawl members are spaced in the circumferential direction relative to the teeth of the ratchet part so that at least some of the pawl members are sequentially engaged with said teeth when increased torque is transmitted between the ratchet part and the pawl part.

5. The freewheeling system according to any of claims 2-4, wherein one or more of said pawl members each comprises at least one slit or gap providing an opening in a direction parallel to said common rotational axis and extending in a lengthwise direction between the free end and the fixed end such that a material thickness of the pawl member transverse to said lengthwise direction on each side of the pawl member is substantially similar.

6. The freewheeling system according to any of the preceding claims, where each of the pawl members of said pawl part extend from its fixed end to its hook-shaped free end in said radial direction R a distance of 2-30mm, such as 5-16mm, and in direction C circumferential around the common rotational axis a distance of 10-60mm, such as 15-40mm, and the thickness of each of the pawl members of said pawl part measured in the direction of said common rotational axis is 1-80mm, such as 2-20mm, and the width of the body of each of said pawl members of said pawl part measured perpendicularly to its extension direction from fixed end to hook-shapedend, as viewed in a direction parallel to said common rotational axis, is 0.2-10mm, such as 1-5mm, and the radius from the said common rotational axis to the tips of said teeth of said ratchet part is 10-80mm, such as 20- 50mm.

7. The freewheeling system according to any of the preceding claims, where said pawl part comprises at least two pawl units wherein each of the said at least two pawl units are offset from each other along said common rotational axis such that there are up to 20mm, such as up to 5mm, between adjacent said at least two pawl units measured parallel to said common rotational axis.

8. The freewheeling system according to any of the preceding claims, where said pawl part is formed as a single continuous body that is rigid between all said fixed ends of all said pawl members.

9. The freewheeling system according to any of the preceding claims, where said freewheeling system is a part of a bike hub providing a freewheeling function between the bike hub shell and the cassette of the bike; or said freewheeling system is a part of a bike cassette providing a freewheeling function between the cassette cogs and the bike hub; or said freewheeling system is at the interface between a bike hub and cassette providing a freewheeling function between the bike hub and the cassette of the bike.

10. The freewheeling system according to any of the preceding claims, where a rigid pawl structure is comprising said pawl part and cassette, said pawl part and cassette of said rigid pawl structure e.g. rigidly connected together by a freehub body, said pawl part of said rigid pawl structure extends into and interacts with said rear hub shell construed to include said ratchet part as a part of its main structure, said rigid pawl structure resting on a hub centre axle by a first pawl-structure-bearing located close to cassette-end of said hub and by a second pawl-structure-bearing spaced apart axially in a direction away from said cassette-end of said hub, while said hub shell is resting on said hub centre axle by a first hub-shell-bearing that is located close to hub’s distal axial end from said cassette-end and is resting on said rigid pawl structure by a second hub-shell-bearing that is located axially closer to the cassette-end of the hub than all the pawl members of said pawl part.11 . A double freewheeling system, comprising• a first freewheeling system, comprising a first pawl part and a first ratchet part, according to any of the preceding claims, and• a second freewheeling system, comprising a second pawl part and a second ratchet part, according to any of the preceding claims, the common rotational axis of the first freewheeling system being the same as the common rotational axis of the second freewheeling system, the radial direction of the second freewheeling system being opposite to the radial direction R of the said first freewheeling system,wherein said first ratchet part and said second ratchet part are rigidly connected and thus form a double ratchet part having a radial gap between the teeth of the first ratchet part and the teeth of the second ratchet part, and wherein said first pawl part and said second pawl part are rigidly connected and thus form a double pawl part being positioned in the radial gap of the double ratchet part, the fixed ends of pawl members of the double pawl part sharing the same support structure at the fixed ends of said pawl members.

12. The double freewheeling system according to claim 11 , wherein the double freewheeling system comprises: a hub centre axle; a double rigid pawl structure, the double rigid pawl structure comprising said double pawl part and a cassette, said double pawl part and said cassette rigidly connected together by a freehub body, said double rigid pawl structure resting on said hub centre axle by a first double-pawl-structure-bearing located at a cassette-end of said hub centre axle and by a second double-pawl-structure-bearing spaced apart axially in a direction away from said cassette-end; and a rear hub shell, the rear hub shell comprising said double ratchet part, said hub shell resting on said hub centre axle by a first hub-shell-bearing located at a distal axial end of the hub centre axle relative to said cassette-end and resting on said hub centre axle by a second hub-shell-bearing located between the first hub-shell-bearing and said second double-pawl-structure-bearing.

13. A freewheeling system according to any of claims 1-8 and 11 -12, where said freewheeling system is a part of an e-bike bottom bracket located electric motor and crankset assembly, and thus provides freewheeling between said e-bike motor and said crankset of said e-bike.

14. A method of operating a freewheeling system for a bike according to any of claims 2-13, wherein several, such as 8 or more, of the pawl members of said pawl part or said double pawl part engage sequentially with teeth of said ratchet part or double ratchet part upon increasing torque applied to said freewheeling system in the torque-transmitting rotational direction, as the bodies of engaged pawl members extend under said applied torque enabling engagement of subsequent pawl members.

15. A bike comprising a freewheeling system from any of claims 1-12, where said bike is a pedal powered bike or an electrically assisted e-bike.

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