Stiffening device for stiffening a bicycle frame and bicycle frame with stiffening device

Description

[0001] The invention relates to a bicycle frame with a stiffening device for stiffening an electric bicycle frame in the area of ​​a cutout accommodating an energy storage device.

[0002] In e-bikes, the electrical energy storage unit is increasingly being integrated into the frame tube, rather than being mounted on top of it as was previously common practice. While this offers a visual advantage, it also increases manufacturing complexity and associated costs, as well as requiring sufficient tube stiffness in this area. The increased effort required to achieve adequate frame stiffness stems from the fact that integrating the power supply unit into the frame tube necessitates a structurally weakening cutout in the tube. This cutout creates an opening through which the electrical energy storage unit can be removed from or reinserted into the frame tube, for example, for charging.

[0003] From DE 10 2017 200 829 A1, it is known to provide the bicycle frame tube, at least in the area of ​​the opening, with individual stiffening ribs, stiffening webs, and the like to achieve the required frame stiffness. These are welded to the relevant tube wall, for example, by means of a material bond. This significantly increases manufacturing costs. The increased manufacturing effort also results, among other things, from the poor accessibility of the installation space within the frame tube, which necessitates complicated and time-consuming manufacturing steps.

[0004] EP 2 998 213 A1 discloses a generic bicycle frame with a stiffening device designed in cross-section as a profile body.

[0005] A similar bicycle frame tube is known from WO 2019 / 167732 A1. A bicycle frame tube is known from CN 110690385 A in which a mounting platform is fixed to two proximal retaining strips.

[0006] The object of the invention is to provide a stiffened bicycle frame with a simplified and inexpensive stiffening of the bicycle frame tube.

[0007] This problem is solved according to the invention with a bicycle frame having a stiffening device having the features of claim 1.

[0008] The stiffening device according to the invention is a self-contained, prefabricated modular component that can be installed in a bicycle frame tube. The stiffening device comprises a first linear stiffening element extending axially within the tube and / or, at a specific angle thereto, at least one second linear stiffening element also extending axially within the tube. The stiffening device according to the invention is manufactured separately from the bicycle frame and can subsequently be installed in various frame shapes. The angled arrangement of the first and second stiffening elements allows for sufficient stiffening of the stiffening device, and thus of the bicycle frame, at least in the area of ​​an opening provided in the bicycle frame tube for mounting an energy storage device. The stiffening device can be the same length as the opening or longer than the opening.The length of the stiffening device can also correspond to the length of the entire bicycle frame tube in question.

[0009] In this context, a first and second stiffening element are understood to be a more or less planar or web-like element, which is not necessarily flat but may also be slightly curved and / or wedge-shaped in cross-section. The first and second stiffening elements are positioned at an angle of at least 45° to each other, so that the area moment of inertia of the stiffening element with respect to longitudinal bending, transverse bending, and / or torsion is high, particularly when installed in the bicycle frame tube and in conjunction with the bicycle frame tube. The second stiffening element preferably projects at least 5 mm, and more preferably at least 8 mm, from the first stiffening element.

[0010] Particularly preferred is the entire stiffening device made of a suitable metal and formed entirely in one piece, i.e., also free of welds.

[0011] The invention relates to a bicycle frame for an electric bicycle, which has a stiffening device in a down tube or a seat tube. The stiffening device is connected to the adjacent tube wall substantially along its entire length, but not necessarily continuously along its entire axial length. The stiffening device is connected to the adjacent tube wall in at least two axial and mutually parallel tracks. This stiffens the respective tube section, particularly with respect to torsion.

[0012] The stiffening device is preferably connected to the tube wall of the relevant bicycle frame tube primarily by frictional and / or positive locking, for example, by a multitude of spot screw connections. The stiffening device can additionally or supplementarily also be bonded to the tube wall by material bonding, for example, by spot welding. The positive or frictional connection between the bicycle frame tube and the stiffening device completely avoids or significantly reduces the effort required for the mechanical connection of the stiffening device to the adjacent tube wall.

[0013] Two opposing bases are provided in the down tube or seat tube. "Opposing" in this context means that the two bases are, for example, mirror images of each other along an axial vertical plane. The bases can be web-like and project radially from the tube wall into the interior of the tube.

[0014] The bases or base supports can extend over part or the entire length of the respective seat tube or down tube. The two bases provide additional stiffening to the down tube or seat tube, and they securely hold the stiffening device and / or serve as solid material for holes or threaded holes into which corresponding bolts or screws are inserted or screwed to fix the stiffening device.

[0015] The bases may have bores and / or axially extending grooves. The bores may be threaded so that screws for attaching the stiffening device to the down tube or seat tube can be screwed into them. The bores, which may be through holes, can be sealed from the outside after the screws are inserted, for example with sealant. Thread-cutting screws can be screwed into the grooves, eliminating the need to create a separate internal thread.

[0016] Longitudinal holes may be provided in the down tube or seat tube to allow the stiffening device to be welded to the down tube or seat tube, preferably from the outside.

[0017] The down tube or the seat tube can be an extruded profile that is usable for all frame shapes.

[0018] In the present context, the term "axial direction" always refers to the longitudinal direction of the bicycle frame tube when a stiffening device is integrated into the frame tube. The stiffening device is linearly elongated in the axial direction.

[0019] The first stiffening element, for example, the base plate of the elongated stiffening element, can have several openings and / or recesses. The openings can have closed, circumferential edges, whereas the edges of the recesses merge into the two opposing side edges of the first stiffening element. The openings and recesses serve two purposes: firstly, to reduce weight, and secondly, to allow access during bicycle frame assembly below or distal to the first stiffening element, for example, to route one or more cables under the stiffening element or between the stiffening element and the adjacent tube wall.

[0020] For ease of manufacture, the openings can be rectangular, honeycomb-shaped, or diamond-shaped, with the diamond-shaped openings having four straight edges. The opposite edges are parallel, and arcuate edges are arranged between two straight edges. The recesses can be V-shaped.

[0021] To ensure that the stiffening device has high stiffness despite the openings and / or recesses, the openings and recesses can be arranged offset from each other in the axial longitudinal direction of the first stiffening element.

[0022] The first stiffening element can have a base plate with openings, to which transition areas extend at a first angle of inclination relative to the base plate. These transition areas then merge into edge sections with a second angle of inclination that is less than the first. Thus, the first stiffening element acquires a trough-like cross-section, forming a receiving bed for an energy storage device.

[0023] Several secondary stiffening elements can be designed within the tube as axially spaced, one-to-one arrangement of strips. This allows for a simple and cost-effective way to increase the stiffness of the stiffening device.

[0024] For the same reason, the multiple strips arranged one behind the other, axially spaced within the tube, can form parallel rows of strips. These parallel rows of strips can preferably be arranged parallel to each other.

[0025] In a very simple embodiment, the stiffening device can be a metal sheet with several holes.

[0026] To achieve high stiffness, the stiffening element can be made of a metal material. Carbon fiber reinforced plastic is recommended if, in addition to high stiffness, low weight is also required for the stiffening element. Glass fiber reinforced plastic can be chosen if less stringent stiffness requirements exist.

[0027] Exemplary embodiments of the inventions are explained in more detail below with reference to the accompanying drawings. Specifically, they show: Fig. 1 a side view of an electric bicycle with a first embodiment of a bicycle frame; Fig. 2 a side view of a second embodiment of the bicycle frame; Fig. 3 a bottom view of the bicycle frame of the Fig. 2 with a stiffening device according to the invention; Fig. 4 a perspective front view of the stiffening device of the Figure 3 ; Fig. 5 a top view of the stiffening device of the Figures 3 and 4 ; Fig. 6 a perspective side view of the stiffening device of the Figures 3-5 Fig. 7 shows a front view of the stiffening device of the Figures 3-6 ; Fig. 8 a perspective front view or a perspective cross-section of a first embodiment of a tube of the bicycle frame of the Figures 1-3 ; Fig. 9 a perspective view of the first embodiment of the tube with a cutout Fig. 8and the stiffening device before assembly; Fig. 10 a perspective view of a second embodiment of a tube of the bicycle frame of the Figures 1-3 , which does not fall within the scope of the patent claims, and the stiffening device before assembly; and Fig. 11 a perspective view of the tube and the stiffening device of the Fig. 10 after assembly.

[0028] Fig. 1 Figure 10 shows an electric bicycle with an electric motor 11 mounted behind a cover 11. The electric bicycle 10 has a bicycle frame 12 with a top tube 13, a down tube 14, a seat tube 15 and a head tube 16.

[0029] An electrical energy storage device 17 is arranged below the downtube 14, or accessible from below within the downtube 14. The energy storage device 17, which is preferably a rechargeable battery, supplies the electric motor 11' with electrical energy during operation.

[0030] The energy storage unit 17 is detachably mounted in the bicycle frame 12. Therefore, it can be removed from the bicycle frame 12 as needed, for example for charging, theft protection, maintenance, or replacement due to wear and tear, and later reattached.

[0031] Fig. 2 and 3 Figure 1 shows a bicycle frame 20 with a down tube 21, in which a cutout 22 is provided for receiving the electrical energy storage device (not shown in detail here). The bicycle frame 20 also has a top tube 23, a seat tube 24, and a head tube 25. A stiffening device 40 is mounted in the down tube 21 (see Figure 2). Figs. 3 to 7 ).

[0032] The stiffening device 40 comprises a first stiffening element 41 extending axially within the lower tube 21 and, at right angles thereto, two second stiffening elements 42 and 43, also extending axially within the lower tube 21. The first stiffening element 41 is provided with several openings 44 and recesses 45 and 46. The openings 44 and the recesses 45 and 46 allow one or more cables to be pulled through below the stiffening device 40. Furthermore, the openings 44 and the recesses 45 and 46 serve to reduce weight.

[0033] The openings 44 have closed, circumferential edges. The openings 44 have four straight edges, with the opposite edges running parallel to each other. Between two straight edges are arcuate edges. Thus, the openings 44 have a rhomboid shape.

[0034] The recesses 45 and 46 are V-shaped. Their edges merge into the two opposing side edges of the first stiffening element 41, so that the recesses 45 and 46 interrupt the side edges.

[0035] The openings 44 and the recesses 45 and 46 are arranged offset from each other in the axial longitudinal direction of the stiffening element 40, thereby achieving the highest possible stiffness.

[0036] The first stiffening element 41 has a base plate 70, to which inclined transition areas 71 and 72 are connected, having a first angle of inclination (see Fig. 7The transition areas 71 and 72 merge into edge sections 73 and 74, which have a second angle of inclination that is smaller than the first angle of inclination. Consequently, the first stiffening element 41 has a trough-like cross-section that forms a receiving bed for the energy storage device. Edge sections 73 and 74 are followed by further edge sections that, for the sake of clarity, are not marked with further reference symbols (see Fig. 5 ).

[0037] Two second stiffening elements 42 and further second stiffening elements 60 are each designed as strips that are arranged axially spaced one behind the other (see Fig. 6 The stiffening elements 42 and 60 are located below the recesses 46, so that the stiffening elements 42 and 60 increase the stiffness of the stiffening device (see Figs. 5 and 6The stiffening elements 42 and 60 form a first row of slats. On the opposite side, there are also several axially spaced second stiffening elements arranged one behind the other, which are positioned below the recesses 45 and thus form a second row of slats that runs parallel to the first row of slats.

[0038] Fig. 8 Figure 80 shows a tube 80, which may preferably be a down tube or a seat tube and is provided for receiving the stiffening device 40.

[0039] A first base 82, having an axially extending groove 81, is arranged in the tube 80. A second base 83, with threaded bores 84, is located mirror-symmetrically opposite the first base 82. The stiffening device 40 can be placed on the bases 82 and 83 during assembly. The stiffening device 40 can be screwed to the tube 80. For this purpose, self-tapping screws can be screwed into the groove 81. The bores 84 can each have an internal thread into which screws can be screwed to fasten the stiffening device 40 to the tube 80. The different bases 82 and 83 in the tube 80 serve in Fig. 8 The illustration shows the two screw connection alternatives. Typically, the pipe 80 has two bases 82 with the groove 81 or two bases 83 with the bores 84.

[0040] Before the stiffening device 40 is inserted into the tube 80, the tube 80 is provided with a cutout 90. The stiffening device 40 is then inserted into the tube 80 in the direction of an arrow 91 (see figure). Fig. 9 The stiffening device 40 is screwed to the tube 80 if the stiffening device 40 is made of carbon fiber reinforced or glass fiber reinforced plastic. However, it is also possible if the stiffening device 40 is made of a metal material.

[0041] If the stiffening device 40 is made of the metal material, it can alternatively be welded to a pipe 100 instead of being screwed together (see Figs. 10 and 11For this purpose, the tube 100 has longitudinal holes 110 through which the edge sections 73 and 74 and the remaining edge sections can be welded to the tube 100. Before welding, the stiffening device 40 can be inserted axially into the tube 100 in the direction of an arrow 101 (see Fig. 10 ) and then welded to the pipe from the outside. To prevent the pipe 100 from warping during welding, it is only provided with a cutout 111 after the welding process. Alternatively, the pipe 100 can first be provided with the cutout 111, then inserted into the pipe 100, and then welded to the pipe 100 from the inside or the outside.

[0042] After the stiffening device 40 has been welded to the tube 100, the tube 100, which is an extruded profile, is welded into the bicycle frame. Reference sign

[0043] 10 Electric bicycle 11 Cover 11 Electric motor 12 Bicycle frame 13 Top tube 14 Down tube 15 Seat tube 16 Head tube 17 Energy storage 20 Bicycle frame 21 Down tube 22 Cutout 23 Top tube 24 Seat tube 25 Head tube 40 Stiffening device 41 Stiffening element 42 Stiffening element 43 Stiffening element 44 Opening 45 Recess 46 Recess 60 stiffening element 70 Base plate 71 Transition area 72 Transition area 73 Edge section 74 Edge section 80Tube 81Nut 82Base 83Base 84Hole 90Excerpt 91Arrow 100 Pipe 101 Arrow 110Long hole 111Cutout

Claims

1. Bicycle frame (12, 20) for an electric bicycle (10), with a lower tube (14, 21) and a saddle tube (15, 24), w herein the bicycle frame (12) is provided with a separate one-piece stiffening device (40) in the lower tube (14, 21) or in the saddle tube (15, 24), which stiffening device serves to stiffen the electric bicycle frame (12, 20) at least in the region of a tube cutout (22, 90), which region accommodates an energy store (17), of a bicycle frame tube (80), w herein the stiffening device (40) is installed in the tube (80) of the bicycle frame (12, 20) and is provided with a first stiffening element (41), which extends axially in the tube (80), and with at least one second stiffening element (42, 43), which likewise extends axially in the tube (80; 100), at a specific angle to the first stiffening element (41), w herein two mutually opposite mounts (82, 83) are provided in the tube (80) of the lower tube (14, 21) or of the saddle tube (15, 24), the stiffening device (40) is connected to the adjacent tube wall of the tube (80) and substantially over the entire length of the stiffening device (40) in two axial lines, which are parallel to one another, with the mounts (82, 83).

2. Bicycle frame (12, 20) according to claim 1, wherein bores (84) and / or axially extending grooves (81) are recessed into the mounts (83, 82).

3. Bicycle frame (12, 20) according to one of the preceding claims, wherein longitudinal holes (110) are provided in the lower tube (14, 21) or in the saddle tube (15, 24).

4. Bicycle frame (12, 20) according to one of the preceding claims, wherein the first stiffening element (41) is provided with a plurality of apertures (44) and / or recesses (45, 46).

5. Bicycle frame (12, 20) according to claim 4, wherein the apertures (44) are rectangular, honeycomb-shaped or rhomb-shaped, wherein the rhomb-shaped apertures (44) are provided with four edges extending in a straight line, and arcuate edges are arranged between two edges extending in a straight line.

6. Bicycle frame (12, 20) according to claim 4 or 5, wherein the apertures (44) and the recesses (45, 46) are arranged offset from one another in the longitudinal direction of the first stiffening element (41).

7. Bicycle frame (12, 20) according to one of claims 4 to 6, wherein the first stiffening element (41) is provided with a base plate (70), which is provided with the apertures (44) and which is adjoined by transition regions (71, 72), which extend at a first angle of inclination obliquely with respect to the base plate (70) and which transition into edge sections (73, 74), which are provided with a second angle of inclination, which is smaller than the first angle of inclination.

8. Bicycle frame (12, 20) according to one of the preceding claims, wherein multiple second stiffening elements (42, 43, 60) are configured as strips, which are arranged axially spaced apart one behind the other in the tube (80).

9. Bicycle frame (12, 20) according to claim 8, wherein the multiple strips, which are arranged axially spaced apart one behind the other in the tube (80), form strip rows, which extend next to one another.