Folding bicycle frame and methods for folding and unfolding said folding bicycle frame

Abstract

A folding bicycle frame A folding bicycle frame comprising: a head tube (4), a triangular frame (6, 7), and a hinge connecting the head tube to the triangular frame to move the head tube and the triangular frame between a folding state and an unfolding state. The hinge comprises: a first hinge part (40) forming at least a part of the head tube and a second hinge part (41) in which the top tube (6) and the down tube (7) are joined. The hinge further comprises a buckle for latching the head tube and the triangular frame in the unfolding state. The buckle comprises: a base; a first engagement portion; a lever pivotally connected to the base; a clasp (63) which is pivotally connected to the lever, the clasp having a handle portion and a second engagement portion configured to cooperate with the first engagement portion thereby latching the head tube and the triangular frame together in the unfolding state.

Description

[0001] FOLDING BICYCLE FRAME AND METHODS FOR FOLDING AND UNFOLDING SAID FOLDING BICYCLE FRAME

[0002] Technical field

[0003] The present invention generally relates to a folding bicycle frame. The present invention further relates to a method of unfolding the folding bicycle frame and a method of folding the folding bicycle frame. The present invention also relates to a folding bicycle and a kit of parts for assembling the folding bicycle.

[0004] Background art

[0005] Folding bicycles are well known and offer various practical advantages. More specifically, the ability to fold the bicycle and its frame onto itself so as to occupy less space, provides an easy way to transport the bicycle when not in use (e.g. by hand, in a suitcase, in a storage compartment of a motor vehicle, etc.). In other words, the possibility of folding the bicycle, thereby significantly reducing its size, makes this means of transport more usable in everyday life, as it eliminates or in any case significantly reduces the problem of not having adequate space available to store the bicycle when it is not to be used.

[0006] A well-known folding bicycle is a Brompton® folding bicycle. The frame of a Brompton® folding bicycle essentially consists of three portions, namely a rear portion, a middle portion and a front portion. The rear portion is configured for mounting a rear wheel thereon and is generally triangular in shape with a seat stay, a chain stay and an upright tube. The middle portion is generally L-shaped with a seat tube and a top tube and a reinforcing tube connecting the seat tube to the top tube. A seat assembly is usually mounted on the top side of the seat tube and a chain assembly is mounted on the bottom bracket located at the bottom side of the seat tube. The front portion is generally T-shaped with a head tube and a top tube. The head tube is configured for mounting a front fork, front wheel and handle bar assembly thereon. Usually, at least the middle portion and the front portion are made from steel.

[0007] The Brompton® folding bicycle frame is foldable due to the presence of two hinges, namely a rear hinge connecting the triangular rear portion to the L-shaped middle portion at the bottom bracket and a front hinge connecting the L-shaped middle portion to the T-shaped front portion. The front hinge essentially connects two tube sections which together form the top tube of the Brompton® folding bicycle frame. The front hinge enables folding the front frame portion to be adjacent the middle frame portion and the rear hinge enables folding the rear frame portion underneath the seat tube so that the rear wheel occupies a space delimited by the L- shaped middle frame portion.

[0008] A known downside of the Brompton® folding bicycle frame is the performance in terms of rigidity and driveability in the unfolded condition. Especially the presence of a hinge dividing the top tube tends to negatively impact rigidity and driveability. Also the absence of a down tube connecting the seat tube to the head tube negatively impacts the frame rigidity.

[0009] A known solution to this problem is to provide a folding bicycle frame having a conventional triangular frame portion. Such a solution is currently commercially available by Ahooga and relies on a conventional triangular front frame (i.e. seat tube, top tube, down tube and head tube) that is hingedly connected at the bottom bracket to a triangular rear frame (i.e. seat stay, chain stay and upright tube). The use of classic triangular front frame drastically improves frame rigidity and thereby driving experience.

[0010] However, this comes with a trade off as the foldability of the bicycle is negatively affected. More specifically, to obtain a sufficiently small folded state of the bicycle, the front wheel has to be removed from the front fork and placed in a dedicated holder on the frame. Such a manual removal of the front wheel is tedious and can lead to errors when unfolding the bicycle. Moreover, the front wheel can also be stolen from the bicycle when folded.

[0011] Disclosure of the invention

[0012] It is an object of the present invention to provide an improved folding bicycle frame which maintains the advantages provided by the use of a triangular front frame but provides a folding bicycle which is easier to fold.

[0013] This object is achieved according to the invention with a folding bicycle frame comprising: a head tube, a triangular frame portion, and a hinge connecting the head tube to the triangular frame portion to move the head tube and the triangular frame portion between a folding state and an unfolding state, the triangular frame portion comprising: a seat tube, a top tube and a down tube, wherein the top tube and the down tube both extend between a first end attached to the seat tube and a second end opposing the first end, the hinge comprising: a first hinge part forming at least a part of the head tube and a second hinge part in which the second ends of the top tube and the down tube are joined. The folding bicycle frame according to the present invention in essence comprises a triangular frame portion that is hingedly connected to the head tube. In this manner, when unfolded, the folding bicycle frame maintains the advantages in rigidity and driving experience provided by the triangular frame. Furthermore, as the head tube is hingedly connected to the triangular frame portion, the head tube can be entirely pivoted to the folded state. As such, the front fork and front wheel in their entirety are pivoted to the folded state. There is thus no longer any need to remove the front wheel thus providing a folding bicycle frame which leads to a folding bicycle which is easier to fold.

[0014] Moreover, different from the Brompton® folding bicycle frame, there is no need to position a hinge in the top tube (or in other tubes). In other words, in the folding bicycle frame according to the present invention, the top tube and down tube can each be integrally formed thus improving rigidity when compared to a tube divided by a hinge.

[0015] In an embodiment of the present invention the hinge forms a comer of the triangular frame portion. This provides a more compact folding bicycle frame when compared to a frame where the top and down tube are joined in a comer with the hinge then interposed between said comer and the head tube. Moreover, this also enables parts of the hinge to extend over a greater vertical distance thus providing a more secure and rigid hinge connection as larger contact areas are possible.

[0016] In an embodiment of the present invention a ratio of a length of the top tube and a shortest distance between the first end of the top tube and the head tube is at least 0.8, preferably 0.85 and more preferably 0.87 and preferably at most 0.97, more preferably at most 0.95 and most preferably at most 0.93. In an embodiment of the present invention a ratio of a length of the down tube and a shortest distance between the first end of the down tube and the head tube is at least 0.7, preferably 0.75 and more preferably 0.8 and preferably at most 0.95, more preferably at most 0.9 and most preferably at most 0.87.

[0017] These embodiments effectively limit the size of the hinge when compared to the size of the triangular frame portion. More specifically, as the hinge must be located between the head tube and the second end of the top and down tubes, these embodiments cause the hinge to extend at most up to about 20% away from the head tube along the top tube direction when compared to the actual top tube length and at most up to about 30% away from the head tube along the down tube direction when compared to the actual down tube length. In these embodiments, the hinge position is thus effectively limited to be adjacent to the head tube thus achieving a compact design. This is also beneficial for the overall rigidity of the bicycle frame as the volume between the head tube and the triangular frame portion is minimized.

[0018] In an embodiment of the present invention the hinge parts further comprise mutually cooperating alignment elements including a female element on one of the first hinge part and the second hinge part and a male element on the other one of the first hinge part and the second hinge part, wherein, in particular, the male element forms a hexahedron, such as a quadrilateral frustum (e.g. a truncated pyramid). These mutually cooperating alignment elements are preferably placed on the side of the hinge opposing the hinge axis.

[0019] The provision of mutually cooperating alignment elements aids in aligning the hinge parts in the unfolded state. This reduces leeway between the hinge parts. This also aids in aligning various electrical and non-electrical connections that may run over the hinge (e.g. from a battery module to a motor in the front wheel or from the handle bar to the chain assembly or brakes). Using a quadrilateral frustum as the male element with a corresponding female element results in the provision of four contact planes between these elements to bear forces in various directions. However, as the hinge itself is subject to a low manufacturing tolerance, only the planes bearing forces in the hinge axis direction (i.e. the top plane and the bottom plane) are usually subjected to forces. Nevertheless the other planes (i.e. the side planes) may also bear surfaces thereby avoiding that these are borne by the hinge which could thereby be damaged. The inclination of the contact planes also aids in correcting any misalignment during unfolding of bicycle frame. Providing the alignment elements on the opposite side of the hinge axis (which itself also acts as an alignment means) places these elements as far away from the hinge axis as possible thus lowering potential forces exerted on the alignment elements when compared to closer placed alignment elements for a same torque motion.

[0020] In an embodiment of the present invention each hinge part is integrally formed, for example cast moulded, preferably from a metal, such as aluminium. Integrally forming each hinge part improves its overall strength and rigidity when compared to a multi-component element. Furthermore, cast moulding allows to obtain relative complex shapes in an economical manner. Aluminium is preferred due to its light weight and high strength and rigidity properties. In an embodiment of the present invention the first hinge part is hollow and configured to hold an electronic control module. The electronic control module may be used for a variety of purposes, e.g. control of lights. However, its main purpose is for use in an electric bicycle to control the battery and motor of the electric bicycle. Providing an interior space for housing the electronic control module firstly shields this from the outside atmosphere. It also eliminates the need to position this externally where it may hamper the folding and / or unfolding operations and may be removed more easily by a nefarious person.

[0021] In an embodiment of the present invention the top tube is hollow and configured to hold a battery module. This also provides shielding for the battery module and avoids the need for any external placement which, as described above, is advantageous.

[0022] In an embodiment of the present invention the triangular frame is constructed from aluminium tubes. Aluminium is preferred due to its light weight and high strength and rigidity properties.

[0023] In an embodiment of the present invention the down tube comprises two separate down tubes which are parallel to one another with a space therebetween configured for receiving a bicycle wheel. In a conventional folding bicycle frame (e.g. the Brompton® folding bicycle), the rear frame portion is pivoted over about 180° with respect to the seat tube so that the rear wheel is below the top tube. However, as the bicycle frame of the present invention relies on a triangular frame with a down tube, the presence of this down tube hinders the known folding operation. The provision of a split down tube overcomes this issue as the rear wheel can be received between the split tube.

[0024] In an embodiment of the present invention the hinge is a flush hinge with a central knuckle in one of the first hinge part and the second hinge part and with external knuckles enclosing the central knuckle in the other one of the first hinge part and the second hinge part. Flush hinges are known to reliably and accurately close. The hinge parts further remain fixed to one another in any possible orientation (which is different from a barrel hinge for example) which is advantageous as the bicycle frame may be in any orientation during transport in the folded state.

[0025] In an embodiment of the present invention the top tube and the seat tube both extend in a longitudinal direction that jointly define a hypothetical plane and wherein the hinge has a hinge axis which is parallel and adjacent to the side to said hypothetical plane. The hinge axis is thus located to the side of the triangular frame part so that the head tube (with front fork and front wheel) can be pivoted to be adjacent the triangular frame part in the folded state.

[0026] In an embodiment of the present invention the folding bicycle frame further comprises: a bottom bracket, a further triangular frame portion having a seat stay, a chain stay and an upright tube, and a further hinge connecting the triangular frame portion to the further triangular frame portion and being configured to move the triangular frame portion and the further triangular frame portion between a folding state and an unfolding state, the further hinge preferably connecting the bottom bracket to the further triangular frame portion. In this embodiment, the triangular frame portion is connected to a conventional triangular rear frame portion that can be pivoted underneath the seat tube to a folded state achieving a compact folded bicycle frame.

[0027] It is another object of the present invention to provide a folding bicycle frame having an improved rigidity.

[0028] This object is achieved according to the invention with a folding bicycle frame comprising: a rear frame portion configured for mounting a rear wheel thereon, a front frame portion configured for mounting a front wheel thereon, a hinge connecting the front frame portion and the rear frame portion to move the front frame portion and the rear frame portion between a folding state and an unfolding state, and a buckle for latching the front frame portion and the rear frame portion in the unfolding state, wherein the buckle comprises: a base connected to one of the front frame portion and the rear frame portion; a first engagement portion provided on the other one of the front frame portion and the rear frame portion; a lever extending between a first end and a second end, the lever being pivotally connected at its first end to the base; a clasp which is pivotally connected to the lever at the second end of the lever, the clasp having a handle portion and a second engagement portion configured to cooperate with the first engagement portion thereby latching the front frame portion and the rear frame portion together in the unfolding state.

[0029] The present buckle is essentially a lever buckle where closing the clasp causes the base and the first engagement portion to be moved towards one another. More specifically, when the frame portions are in their unfolded position and the engagement portions are engaged, the clasp, the lever and the base form a triangular set-up. Pushing the clasp towards the base in this way causes a force extending in the direction of the lever to be exerted on the base and a force pulling on the first engagement portion. These forces are (in part) directed against one another so that the first engagement portion is pulled towards the base. Due to this buckle construction, the frame portions are pulled tightly together during closing of the buckle. Thereby improving the rigidity of the hinge connection between the frame portions and thus the rigidity of the frame as a whole in the unfolded state.

[0030] The buckling operation is also very easy for a user to perform which is another advantage when compared to known buckles that tend to rely on a clamping element that is clamped onto the hinge parts by tightening a nut element.

[0031] In an embodiment of the present invention the handle portion is located opposite the second engagement portion with the lever being pivotally connected to the clasp at a connection region which is located between the handle portion and the second engagement portion. In this way, the clasp acts as a second-order lever with the engagement portions forming the fulcrum. There is thus a force amplification between the user’s exerted force on the handle portion and the force exerted on the lever which depends on the distance between the handle portion and the connection region. This allows a user to exert a lower force while the lever still exerts a large force to push the base and the first engagement portion together.

[0032] In an embodiment of the present invention the buckle further comprises a first biasing member urging the lever towards the base. The first biasing member particularly comprises a tension spring connecting the lever to the base, the tension spring preferably being connected to the lever near its second end. This aids in preventing that the lever would rattle and / or reduces the risk that the lever would displace with respect to the base when the bicycle frame is in its folded state. A tension spring provides an easy design to achieve the desired urging. A connection at the second end of the lever reduces the spring force needed to maintain the lever against the base.

[0033] In an embodiment of the present invention the buckle further comprises a second biasing member urging the clasp to a rest position with respect to the lever, the second biasing member preferably comprising a spring, in particular a torsion spring, disposed between the clasp and the lever. This aids in preventing that the clasp would rattle and / or reduces the risk that the clasp would displace with respect to the lever when the bicycle frame is in its folded state. A torsion spring provides an easy design to achieve the desired urging as this may be disposed around the pivot axis connecting the clasp to the lever.

[0034] In an embodiment of the present invention the lever comprises a base member and a replaceable spacer, wherein replacing the replaceable spacer allows varying a length of the lever. As the length of the lever is a key element in determining the force with which the base and the first engagement portion are pulled towards one another, being able to vary this length is advantageous. This can, for example, be used to account for wear and tear defects that occur over time by adding in a longer or short spacer.

[0035] In an embodiment of the present invention the base extends between a proximal region and a distal region which are opposite one another, the proximal region abutting the other one of the front frame portion and the rear frame portion when the front frame portion and the rear frame portion are in the unfolding state, wherein the lever is pivotally connected to the base at its proximal region. As the lever exerts the closing force on the base, it is advantageous to place the location where the force is exerted as close as possible to the part of the base that abuts against the other one of the front frame portion and the rear frame portion on which the first engagement portion is provided.

[0036] In an embodiment of the present invention the first engagement portion and the second engagement portion both comprise a hook shaped element. This enables the portions to remain engaged even under relative rotation of the elements involved.

[0037] In an embodiment of the present invention the buckle further comprises a safety latch cooperating with the clasp, the safety latch being pivotally mounted on the base between an unlatching position in which the safety latch is not engaged with the clasp and a latching position in which the safety latch is engaged with the clasp. The buckle preferably comprises a third biasing member which urges the safety latch towards its latching position, the third biasing member particularly being a spring, such as a torsion spring, disposed between the base and the safety latch. The clasp preferably being provided with an inclined surface facing the safety latch configured for moving the safety latch against the third biasing member when the clasp is moved to its latching position.

[0038] An additional safety latch to maintain the clasp in its latching position improves the overall stability and robustness of the buckle. Spring biasing this safety latch towards its latching position further avoids that a user would forget to apply the safety latch. A torsion spring provides an easy design to achieve the desired urging as this may be disposed around the pivot axis connecting the safety latch to the base. Designing the clasp to have an inclined surface to automatically displace the additional safety latch against the third biasing member when closing the clasp allows a user to close the buckle with a single hand. In an embodiment of the present invention the base has an abutment and the lever has a protrusion, in particular at its first end, such that the protrusion abuts against the abutment when pivoting the lever away from the base to hinder and preferably stop a pivoting motion of the lever. The protrusion and corresponding abutment act as an additional safety mechanism by limiting the opening movement of the lever with respect to the base. This allows, for example, limiting the movement to such an opening angle in which the first and second engagement portions are still engaged thus preventing that the hinge parts become accidentally loose from one another.

[0039] In an embodiment of the present invention the front frame portion comprises a head tube and the rear frame portion comprises a triangular frame portion, the triangular frame portion comprising: a seat tube, a top tube and a down tube, wherein the top tube and the down tube both extend between a first end attached to the seat tube and a second end opposing the first end, the hinge comprising: a first hinge part forming at least a part of the head tube and a second hinge part in which the second ends of the top tube and the down tube are joined.

[0040] As described above, in this embodiment, the folding bicycle frame in essence comprises a triangular frame portion that is hingedly connected to the head tube. In this manner, when unfolded, the folding bicycle frame remains the advantages in rigidity and driving experience provided by the triangular frame. Furthermore, as the head tube is hingedly connected to the triangular frame portion, the head tube can be entirely pivoted to the folded state. As such, the front fork and front wheel in their entirety are pivoted to the folded state. There is thus no longer any need to remove the front wheel thus providing a folding bicycle frame which leads to a folding bicycle which is easier to fold. Other preferred features and advantages in relation to the triangular frame portion that is hingedly connected to the head tube have been described above.

[0041] The further object of the present invention is also achieved by a method of unfolding bicycle frame described above, the method comprising: moving the front frame portion and the rear frame portion to their unfolding state; moving the clasp to engage the first engagement portion and the second engagement portion with one another; and pushing the handle portion of the clasp towards the base causing the lever to push the base towards the other one of the front frame portion and the rear frame portion. The further object of the present invention is also achieved by a method of folding bicycle frame described above, the method comprising: optionally pivoting the safety latch to its unlatching position; pulling the handle portion of the clasp away from the base; moving the clasp to disengage the first engagement portion and the second engagement portion from one another; and moving the front frame portion and the rear frame portion to their folding state.

[0042] The object(s) of the present invention is / are also achieved by a folding bicycle comprising the folding bicycle frame described above.

[0043] In an embodiment of the present invention the hinge has a hinge axis which, when the folding bicycle is unfolded on a level surface, is angled with respect to a direction normal to said level surface. This means that, when folding the front frame portion (e.g. the head tube) with respect to the triangular frame portion, a front wheel mounted on the front frame portion will undergo a change in elevation compared to the triangular frame portion. Determining this angle enables aligning the front and rear wheel in the folded state of the bicycle frame. The angle is preferably a positive angle when viewed in a right-handed coordinate system. This means that the front wheel mounted on the front frame portion will be rotated upwards and away from the level surface.

[0044] The object(s) of the present invention is / are also achieved by a kit of parts for assembling the folding bicycle, the kit of parts comprising the folding bicycle frame described above. The kit of parts may optionally comprises at least one of: a front wheel, a rear wheel, a seat assembly, a handle bar assembly, a chain assembly, and a brake assembly.

[0045] The invention will be further explained by means of the following description and the appended figures.

[0046] Figures 1A and IB show opposing side views of a folding bicycle according to the present invention in the unfolded state.

[0047] Figures 2A and 2B show opposing side views of a folding bicycle according to the present invention in the folded state.

[0048] Figures 3 and 4 show opposing side views of the hinge connecting the triangular frame and head tube in a partially opened state. Figure 5 shows a perspective view of the first hinge part of the hinge connecting the triangular frame and head tube.

[0049] Figure 6 shows a perspective view of the second hinge part of the hinge connecting the triangular frame and head tube.

[0050] Figure 7 shows a side view of a buckle for latching hinge connecting the triangular frame and head tube.

[0051] Figure 8 shows a partial cross-sectional side view of the buckle in the latching state.

[0052] Figures 9 to 12 show cross-sections through the buckle in respectively the opened, the engaged, the depressed, and the latched state of the buckle for latching hinge connecting the triangular frame and head tube.

[0053] Figure 13 shows a cross-section through the buckle in the engaged state and illustrates the torsion spring between the lever and the clasp.

[0054] Figure 14 shows a cross-section through the buckle in the engaged state and illustrates the stop limiting opening movement of the lever with respect to the base.

[0055] Description of the invention

[0056] The present invention will be described with respect to particular embodiments and with reference to certain drawings but the invention is not limited thereto but only by the claims. The drawings described are only schematic and are non-limiting. In the drawings, the size of some of the elements may be exaggerated and not drawn on scale for illustrative purposes. The dimensions and the relative dimensions do not necessarily correspond to actual reductions to practice of the invention.

[0057] Furthermore, the terms first, second, third and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequential or chronological order. The terms are interchangeable under appropriate circumstances and the embodiments of the invention can operate in other sequences than described or illustrated herein.

[0058] Moreover, the terms top, bottom, over, under, left, right, front, back, and the like in the description and the claims are used for descriptive purposes. The terms so used are interchangeable under appropriate circumstances and the embodiments of the invention described herein can operate in other orientations than described or illustrated herein. Furthermore, the various embodiments, although referred to as “preferred” are to be construed as exemplary manners in which the invention may be implemented rather than as limiting the scope of the invention.

[0059] Figures 1A and IB show opposing side views of a folding bicycle 1 according to the present invention in the unfolded state. The folding bicycle 1 comprises three separate frame portions, namely a head tube 4, a triangular front frame 5 and a triangular rear frame 25. A first hinge 48 is located between the head tube 4 and the triangular front frame 5 and a second hinge 36 is located between the triangular front frame 5 and the triangular rear frame 25. The folding bicycle 1 of figures 1A and IB is shown in the folded state in figure 2A and 2B.

[0060] The head tube 4 is a conventional hollow tube section having a top end 4a and a bottom end 4b. A handle bar assembly 16 is mounted on the top end 4a. The handle bar assembly 16 comprises a head set 15 on which a handle bar 14 is mounted. In the illustrated embodiments, a further hinge 52 is located between the head tube 4 and the head set 15 so as to allow pivoting the entire handle bar assembly 16 over an angle of 180° to be adjacent the head tube 4 as shown in figure 2B. At the bottom end 4b of the head tube 4 a front fork 18 is mounted on which a front wheel 19 is mounted. This assembly of a head tube 4 with hingedly connected handle bar assembly 16 and fixedly connected front fork 18 is known in the context of folding bicycles (e.g. from the Brompton® folding bicycle) and will not be described further.

[0061] The triangular rear frame 25 comprises an upright support 22, a seat stay 23 and a chain stay 24. A rear wheel 20 is mounted on the triangular rear frame 25 where the seat stay 23 and the chain stay 24 are joined. The conventional parts of chain assembly are also mounted on the triangular rear frame 25, such as a rear derailleur 35 and / or a cassette (not shown). A hinge 36 is interposed between the triangular rear frame 25 and the triangular front frame 5. This hinge 36 is located between the bottom end 8b of the seat tube 8 and the bottom end 22b of the upright support 22. The hinge 36 allows pivoting the entire triangular rear frame 25 over an angle of 180° so that the upright support 22 is in line with the seat tube 8 as shown in figure 2A. At the top end 22a of the upright support 22 a support wheel 39 is provided. As shown in figure 2B, in the folded state of the bicycle 1, the support wheel 39 can be used to roll the folded bicycle along a ground surface. This assembly of a triangular rear frame 25 that is hingedly connected to the bottom of the seat tube 8 with a supporting wheel 39 at the top end 22a of the upright support 22 is known in the context of folding bicycles (e.g. from the Brompton® folding bicycle) and will not be described further.

[0062] As best shown in figure 4, the down tube 7 in the illustrated embodiment involves two parallel down tubes 7i, 7ii with a space 50 therebetween. As shown in figure 2A, this allows the rear wheel 20 to be received between the parallel down tubes 7i, 7ii in the folded state. Such a split down tube 7 thus allows a compact folded state of the bicycle without the need to have curved or offset down tube.

[0063] The seat tube 8 extends between a top end 8a and a bottom end 8b. A seat assembly 12 is mounted on the top end 8a of the seat tube 8. The seat assembly 12 comprises a seatpost 10 and a saddle 11. The seatpost 10 can be nearly entirely slid into the seat tube 8 in the folded state as shown in figures 2A and 2B. At the bottom end 8b of the seat tube 8 a bottom bracket 30 is provided. The conventional parts of chain assembly are mounted on the bottom bracket 30, such as a chainring 33, a crankshaft, crankarms 34, pedals 37, a chain 32, etc. The seat assembly 12 and the chain assembly are also known in the context of folding bicycles (e.g. from the Brompton® folding bicycle) and will not be described further.

[0064] Naturally other common components of a bicycle (e.g. brakes, spat guards, baggage carrier, lights, etc.) may also be mounted on the folding bicycle frame depending on the bicycle design.

[0065] The present invention is generally focussed on the hinge 48 connecting the head tube 4 and the triangular front frame 5 which will be described with respect to figures 3 to 6. The present invention is also focussed on a buckle for the hinge 48 which will be described with respect to figures 7 to 14. Although it should be readily understood that the buckle can also be used for a differently positioned hinge, e.g. a hinge dividing the top tube as in the Brompton® folding bicycle.

[0066] The hinge 48 comprises a front hinge part 40 (shown in figure 5) and a rear hinge part 41 (shown in figure 6). Each hinge part 40, 41 is, in the illustrated embodiment, an integrally formed part and is obtained by cast moulding aluminium. However other materials (e.g. steel, carbon fibre, synthetics, etc.) and / or other manufacturing techniques (e.g. additive manufacturing such as 3D printing) could also be used to form the hinge parts 40, 41. As shown in figures 1A, IB, 3 and 4, the hinge 48 forms a comer of the triangular front frame 5. The front hinge part 40 is integrally formed with the head tube 4 and comprises a hollow space. As shown in figure 3, an electronic control module 49 can be placed inside the front hinge part 40. As such an electronic control module 49 is typically required for electric bicycles, it is advantageous to place this inside a component of the bicycle frame as described above.

[0067] The front hinge part 40 and the rear hinge part 41 are connected as a flush hinge having a central knuckle 45 and adjacent external knuckles 46. In the illustrated embodiment, the central knuckle 45 is on the front hinge part 40 and the external knuckles 46 are on the rear hinge part 41, but a reversal is possible. The knuckles 45 revolve around a hinge axis 47 and are connected by a hinge pin (not shown). The hinge axis 47 is outside of the boundaries of the head tube 4 and the triangular front frame 5 allowing the front hinge part 40 with the head tube 4 to be pivoted to a folded state adjacent the second hinge part 41 with the triangular front frame 5 as shown in figure 2B.

[0068] As shown in figure 1A, the hinge axis 47 makes an angle a with a level ground surface when the bicycle 1 is unfolded. In the illustrated embodiment, the angle a is a positive angle (e.g. about 5°) when compared to the normal direction in a right-handed coordinate system. This causes the front of the bicycle 1 (i.e. the front wheel 19 and fork 18) to be lifted upwards from the ground surface during folding to avoid that the front wheel 19 contacts the ground surface when having to move the folded bicycle (see figure 2B). Varying this angle a may also be done so as to ensure that the wheel 19, 20 are substantially aligned in the folded state as shown in figures 2A and 2B.

[0069] The second hinge part 41 joins the top tube 6 and the down tube 7 (or split down tube 7i, 7ii in the illustrated embodiment). As such, the top tube 6 extends between a first end 6a where it is joined to the top end 8a of the seat tube and a second end 6b that is joined to the second hinge part 41 and the down tube 7 extends between a first end 7a where it is joined to the bottom end 8b of the seat tube and a second end 7b that is joined to the second hinge part 41. This joining may be achieved in a variety of ways, e.g. using mating connectors. However, in the illustrated embodiment, the second ends 6b, 7b are welded to the second hinge part 41 to have a rigid and strong connection.

[0070] As shown in figure 6, the top tube 6 is hollow and the second hinge part 41 is provided with a corresponding opening 81 to allow access to the hollow top tube 6. This enables placing a battery module 80 inside the hollow top tube 6 as shown in figure 3. An electric folding bicycle is thus obtained with the advantages described above of an internally stored battery module.

[0071] As shown in figures 5 and 6, the hinge parts 40, 41 are provided with mutually cooperating alignment means involving a male element 43 and a female element 44. In the illustrated embodiment the male element 43 is provided on the first hinge part 40 whereas the female element 44 is provided on the second hinge part 41. However, the reverse placement may also be applied. The mutually cooperating alignment means 43, 44 are provided on the hinge part 40, 41 on the opposite side of the hinge knuckles 45, 46 which, as described is advantageous as the forces that the mutually cooperating alignment means are able to handle are maximized (for a same torque closing motion of the hinge parts 40, 41) due to the radial distance to the hinge axis 47 being maximized.

[0072] In the illustrated embodiment, the male element 43 is formed as a quadrilateral frustum, i.e. a truncated pyramid, with inclined sides. As such, the top of the male element 43 is smaller than its base allowing the male element 43 to be easily received in the female element 44 having an opening which matches the base even when misaligned. The various inclined sides also increase the possible contact area between the mutually cooperating alignment elements thus allowing larger forces to be exerted thereon whilst avoiding high pressures that could damage the elements 43, 44.

[0073] It will be readily appreciated that mutually cooperating alignment means with various distinctly located male / female elements may be used. Also the shapes of the elements are not limited to the illustrated quadrilateral frustum, e.g. cylinder or elliptical based (such as a pin), cuboid, semi- spherical, etc.

[0074] In the illustrated embodiment, a ratio of a length of the top tube and a shortest distance between the first end of the top tube and the head tube is about 91% and a ratio of a length of the down tube and a shortest distance between the first end of the down tube and the head tube is about 85%. However, as described above, other ratios are possible.

[0075] The buckle generally comprises a base 68 on one of the hinge parts and a first engagement portion 65 on the other one of the hinge parts. In the illustrated embodiment this is formed 68 as an integral part of the front hinge part 40 and the first engagement portion 65 is integrally formed as part of the rear hinge part 41. However, the roles could be reversed with the base being provided on the rear hinge part and the first engagement portion on the front hinge part. Furthermore, the base and / or the first engagement portion could also be formed as a separate element that is fixed on one of the hinge parts. The base 68 extends between a proximal end 68a and an opposing distal end 68b. In the unfolded state of the hinge parts 40, 41, the proximal end 68a abuts against the other hinge part (i.e. the rear hinge part 41 in the illustrated embodiment). The distal end 68b is the other end of the front hinge part 40 which is, for example, contiguous with the head tube 4.

[0076] The buckle further generally comprises a lever 71 which extends between a first end 71a and a second end 71b. The lever 71 is pivotally attached at its first end 71a to the base 68. In the illustrated embodiment as shown in figure 7, the pivotal connection takes the form of a flush hinge connection with a central knuckle 68c provided on the base 68 and external knuckles 71c that are adjacent the opposing sides of the central knuckle 68c. A single axle or, as in the illustrated embodiment, two separate axles 82 connect the various knuckles 68c, 71c to pivotally connect the lever 71 to the base 68. It will be appreciated that other knuckle configurations are possible, e.g. the lever forming the central knuckle or only involving two knuckles.

[0077] The buckle further generally comprises a clasp 63 that is pivotally connected to the lever 71 at the second end 71b thereof. The clasp 63 comprises a handle portion 72 and a second engagement portion 67. In the illustrated embodiment, the clasp 63 is pivotally connected to the lever 71 by means of a joint axle 85 allowing the pivoting motion.

[0078] The general operation of the buckle will be described now with reference to figures 9 to 11. Figure 9 shows the buckle in its open position with the clasp 63 not contacting the rear hinge part 41. In this position, the hinge parts 40, 41 are unconnected and can be moved into the open state to fold the bicycle frame. In order to close the buckle, the clasp 63 is moved so that the engagement portions 65, 67 engage one another as shown in figure 10. A user then pushes on the handle portion 72 to move the lever 71 towards the base 68. This pushing motion urges the base 68 (i.e. the front hinge part 40) and the first engagement portion 65 (i.e. the rear hinge part 41) towards one another. In this manner, the lever 71 is moved against the base 68 to the state shown in figure 11. The buckle is then latched and the hinge parts 40, 41 cannot rotate with respect to one another.

[0079] In the illustrated embodiment, the engagement portions 65, 67 are both hook-shaped. This is advantageous as the clasp 63 rotates with respect to the first engagement portion 65 during latching of buckle and the hook shape reduces the risk that the engagement portions 65, 67 become disengaged due to the rotation. The hooks can also be formed to be able to handle high forces and pressures (e.g. by increasing the material thickness). The design is also simpler when compared to a hook engaging an opening or the like.

[0080] The lever 71 is connected to the clasp 63 at a connection region 73 which is located between the handle portion 72 and the second engagement portion 67. By this construction, the clasp 73 acts as a second order lever about the fulcrum formed by the engaged engagement portions 65, 67 having a force amplification between the force exerted on the handle portion 72 and the force exerted on the lever 71.

[0081] As shown in the illustrated embodiment, the first end 7 la of the lever 71 is connected to the base 68 near its proximal end 68a thus minimizing the distance between the location where the closing force is exerted on the base 68, i.e. base element 68c, and the location where the engagement portions 65, 67 engage.

[0082] As shown in figure 13, a biasing member 86 (a torsion spring in the illustrated embodiment) is disposed between the lever 71 and the clasp 63. More specifically, the torsion spring is disposed around the axle 85 and has a first free end 86a engaging the lever 71 and a second free end 86b engaging the clasp 63. This biasing member 86 urges the clasp 71 towards a rest position (shown in figure 13) with respect to the lever 71 to avoid rattling in the folded state of the hinge parts. So as to avoid overloading the appended figures, the biasing member 86 is only shown in figure 13.

[0083] As shown in figure 10, a biasing member 74 (a tension spring in the illustrated embodiment) is disposed between the lever 71 and the base 68. More specifically, the tension spring connects the second end 71b of the lever 71 to the base 68. This biasing member 74 urges the lever 71 towards the base 68 to avoid rattling in the folded state of the hinge parts. So as to avoid overloading the appended figures, the biasing member 74 is only shown in figure 10.

[0084] As shown in figure 14, the lever 71 is provided with a protrusion 83 which cooperates with an abutment 84 on the base 68 to hinder an opening movement of the lever 71 with respect to the base 68. More specifically, the protrusion 83 at the first end 71a of the lever 71 forms a flat surface which engages the flat abutment surface 84 which is part of the base 68. The surface-to-surface contact prevents a further pivoting motion of the lever 71 with respect to the base 68. As shown in figure 14, the protrusion 83 and abutment 84 together with the biasing member 86 between the lever 71 and the clasp 63 ensure that, even when the clasp 63 becomes accidentally (i.e. without user intervention) loose in the unfolded state, the engagement parts 65, 67 remain engaged with one another thus still preventing a pivoting motion of the hinge parts 40, 41. An actual user intervention is needed to move the clasp 63 against the biasing member 86 to enable disengaging the engagement hooks 65, 67.

[0085] As shown in figure 8, in the illustrated embodiment, the lever 71 is constructed from three distinct different elements. More specifically, there is a first end part 62, a replaceable spacer 69, and a second end part 61. These parts 61 , 62, 69 are fixed together by conventional means, e.g. bolts (not shown) which fit in corresponding bolt openings 70. The construction allows deconstructing the lever 71 and replacing the spacer 69 with a different spacer. This can be used to vary the total length of the lever 71 which, as described above, is advantageous. It will be readily appreciated that the spacer and second end part could be formed as a single element which is replaceable with respect to the first end part.

[0086] In the illustrated embodiment, the buckle further comprises a safety latch 66. The safety latch 66 is pivotally connected to the base 68. In the illustrated embodiment, the safety latch 66 is pivotally connected to the base 68 by means of a joint axle 88 allowing the pivoting motion. In the latching state of the buckle (see figure 11), the safety latch 66 can be moved to a latching position to latch the clasp 63 as shown in figure 12. To this end, the safety latch 66 is provided with a catch 91 (e.g. a hook-shaped hole) which engages on a corresponding protrusion 92 provided on the clasp 63 as shown in figure 12. A user who desires to unclasp the buckle thus first has to manually move the safety latch 66 from the latching state in figure 12 to an unlatching state as shown in figure 11 before being able to lift the clasp 63 away from the base 68.

[0087] As shown in figure 9, a biasing member 89 (a torsion spring in the illustrated embodiment) is disposed between the safety latch 66 and the base 68. More specifically, the torsion spring is disposed around the axle 88 and has a first free end 89a engaging the base 68 and a second free end 89b engaging the safety latch 66. This biasing member 89 urges the safety latch 66 towards a latching position (shown in figure 9). An inclined surface 90 is provided on the clasp 63 to move the safety latch 66 against the biasing member 89 when closing the clasp 63 as shown in figure 11. The biasing member 89 then causes the safety latch 66 to automatically latch the clasp 63. So as to avoid overloading the appended figures, the biasing member 89 is only shown in figure 9. Although aspects of the present disclosure have been described with respect to specific embodiments, it will be readily appreciated that these aspects may be implemented in other forms within the scope of the invention as defined by the claims.

Claims

Claims1. A folding bicycle frame comprising: a head tube (4), a triangular frame portion (5), and a hinge (48) connecting the head tube to the triangular frame portion to move the head tube and the triangular frame portion between a folding state and an unfolding state, the triangular frame portion comprising: a seat tube (8), a top tube (6) and a down tube (7), wherein the top tube and the down tube both extend between a first end (6a, 7a) attached to the seat tube and a second end (6b, 7b) opposing the first end, the hinge comprising: a first hinge part (40) forming at least a part of the head tube and a second hinge part (41) in which the second ends of the top tube and the down tube are joined.

2. The folding bicycle frame according to claim 1, wherein the hinge forms a corner of the triangular frame portion.

3. The folding bicycle frame according to claim 1 or 2, wherein a ratio of a length of the top tube and a shortest distance between the first end of the top tube and the head tube is at least 0.8, preferably 0.85 and more preferably 0.87 and preferably at most 0.97, more preferably at most 0.95 and most preferably at most 0.93.

4. The folding bicycle frame according to any one of the preceding claims, wherein a ratio of a length of the down tube and a shortest distance between the first end of the down tube and the head tube is at least 0.7, preferably 0.75 and more preferably 0.8 and preferably at most 0.95, more preferably at most 0.9 and most preferably at most 0.87.

5. The folding bicycle frame according to any one of the preceding claims, wherein the hinge parts further comprise mutually cooperating alignment elements including a female (44) element on one of the first hinge part and the second hinge part and a male element (43) on the other one of the first hinge part and the second hinge part, wherein, in particular, the male element forms a hexahedron, such as a quadrilateral frustum.

6. The folding bicycle frame according to any one of the preceding claims, wherein each hinge part is integrally formed, for example cast moulded, preferably from a metal, such as aluminium.

7. The folding bicycle frame according to any one of the preceding claims, wherein the first hinge part is hollow and configured to hold an electronic control module (49).

8. The folding bicycle frame according to any one of the preceding claims, wherein the top tube is hollow and configured to hold a battery module (80).

9. The folding bicycle frame according to any one of the preceding claims, wherein the down tube comprises two separate down tubes (7i, 7ii) which are parallel to one another with a space (50) therebetween configured for receiving a bicycle wheel.

10. The folding bicycle frame according to any one of the preceding claims, wherein the hinge is a flush hinge with a central knuckle (45) in one of the first hinge part and the second hinge part and with external knuckles (46) enclosing the central knuckle in the other one of the first hinge part and the second hinge part.

11. The folding bicycle frame according to any one of the preceding claims, wherein the top tube and the seat tube both extend in a longitudinal direction that jointly define a hypothetical plane and wherein the hinge has a hinge axis (47) which is parallel and adjacent to the side to said hypothetical plane.

12. The folding bicycle frame according to any one of the preceding claims, wherein the folding bicycle frame further comprises: a bottom bracket (30), a further triangular frame portion (25) having a seat stay (23), a chain stay (24) and an upright tube (22), and a further hinge (36) connecting the triangular frame portion to the further triangular frame portion and to move the triangular frame portion and the further triangular frame portion between a folding state and an unfolding state, the further hinge preferably connecting the bottom bracket to the further triangular frame portion.

13. A folding bicycle frame comprising: a rear frame portion (5, 25) configured for mounting a rear wheel thereon, a front frame portion (4) configured for mounting a front wheel thereon, a hinge (48) connecting the front frame portion and the rear frame portion to move the front frame portion and the rear frame portion between a folding state and an unfolding state, and a buckle for latching the front frame portion and the rear frame portion in the unfolding state, wherein the buckle comprises:- a base (68) connected to one of the front frame portion and the rear frame portion;- a first engagement portion (67) provided on the other one of the front frame portion and the rear frame portion;- a lever (71) extending between a first end (71a) and a second end (71b), the lever being pivotally connected at its first end to the base;- a clasp (63) which is pivotally connected to the lever at the second end of the lever, the clasp having a handle portion (72) and a second engagement portion (67) configured to cooperate with the first engagement portion thereby latching the front frame portion and the rear frame portion together in the unfolding state.

14. The folding bicycle frame according to claim 13, wherein the handle portion is located opposite the second engagement portion with the lever being pivotally connected to the clasp at a connection region (73) which is located between the handle portion and the second engagement portion.

15. The folding bicycle frame according to claim 13 or 14, wherein the buckle further comprises a first biasing member (74) urging the lever towards the base, wherein the first biasing member preferably comprises a tension spring connecting the lever to the base, the tension spring particularly being connected to the lever near its second end.

16. The folding bicycle frame according to any one of claims 13 to 15, wherein the buckle further comprises a second biasing member (86) urging the clasp to a rest position with respect to the lever, the second biasing member preferably comprising a spring, in particular a torsion spring, disposed between the clasp and the lever.

17. The folding bicycle frame according to any one of claims 13 to 16, wherein the lever comprises a base member (62) and a replaceable spacer (69), wherein replacing the replaceable spacer allows varying a length of the lever.

18. The folding bicycle frame according to any one of claims 13 to 17, wherein the base extends between a proximal region (68a) and a distal region (68b) which are opposite one another, the proximal region abutting the other one of the front frame portion and the rear frame portion when the front frame portion and the rear frame portion are in the unfolding state, wherein the lever is pivotally connected to the base at its proximal region.

19. The folding bicycle frame according to any one of claims 13 to 18, wherein the first engagement portion and the second engagement portion both comprise a hook shaped element.

20. The folding bicycle frame according to any one of claims 13 to 19, wherein the buckle further comprises a safety latch (66) cooperating with the clasp, the safety latch being pivotally mounted on the base between an unlatching position in which the safety latch is not engaged with the clasp and a latching position in which the safety latch is engaged with the clasp.

21. The folding bicycle frame according to claim 20, wherein the buckle comprises a third biasing member (89) which urges the safety latch towards its latching position, the third biasing member preferably being a spring, in particular a torsion spring, disposed between the base and the safety latch.

22. The folding bicycle frame according to claim 21, wherein the clasp is provided with an inclined surface (90) facing the safety latch configured for moving the safety latch against the third biasing member when the clasp is moved to its latching position.

23. The folding bicycle frame according to any one of claims 13 to 22, wherein the base has an abutment (84) and the lever has a protrusion (83), in particular at its first end, suchthat the protrusion abuts against the abutment when pivoting the lever away from the base to hinder and preferably stop a pivoting motion of the lever.

24. The folding bicycle frame according to any one of claims 13 to 23, wherein the front frame portion comprises a head tube (4) and the rear frame portion comprises a triangular frame portion (5), the triangular frame portion comprising: a seat tube (8), a top tube (6) and a down tube (7), wherein the top tube and the down tube both extend between a first end (6a, 7a) attached to the seat tube and a second end (6b, 7b) opposing the first end, the hinge comprising: a first hinge part (40) forming at least a part of the head tube and a second hinge part (41) in which the second ends of the top tube and the down tube are joined.

25. The folding bicycle frame according to claim 24, wherein the folding bicycle frame further comprises the features of the folding bicycle frame of any one of claims 2 to 12.

26. A method of unfolding the folding bicycle frame according to any one of claims 13 to 25, the method comprising:- moving the front frame portion (4) and the rear frame portion (5) to their unfolding state;- moving the clasp (63) to engage the first engagement portion (65) and the second engagement portion (67) with one another; and- pushing the handle portion (72) of the clasp towards the base causing the lever (71) to push the base towards the other one of the front frame portion and the rear frame portion.

27. A method of folding the folding bicycle frame according to any one of claims 13 to 25, the method comprising:- optionally pivoting the safety latch (66) to its unlatching position;- pulling the handle portion (72) of the clasp (63) away from the base (68);- moving the clasp to disengage the first engagement portion (65) and the second engagement portion (67) from one another; and- moving the front frame portion (4) and the rear frame portion (5) to their folding state.

28. A folding bicycle comprising the folding bicycle frame according to any one of claims 1 to 25.

29. The folding bicycle according to claim 27, wherein the hinge has a hinge axis (47) which, when the folding bicycle is unfolded on a level surface, forms an angle (a) with respect to a direction normal to said level surface.

30. A kit of parts for assembling the folding bicycle according to claim 28 or 29, the kit of parts comprising the folding bicycle frame according to any one of claims 1 to 25 and preferably further comprising at least one of: a front wheel (19), a rear wheel (20), a seat assembly (12), a handle bar assembly (16), a chain assembly, and a brake assembly.

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