bicycle frame

Abstract

Bicycle frame (1) for an electrically powered bicycle, wherein the bicycle frame (1) comprises frame parts selected from a group of frame parts comprising a top tube, a down tube (6), a seat tube (5), a head tube (7), chainstays (3) and seat stays (4), and at least one motor bearing housing (8) connecting the seat tube (5) and the down tube (6), wherein at least the down tube (6) is designed as a hollow profile with at least one compartment (11) for receiving at least one electrical energy storage device, wherein at least the down tube (8) comprises a first and at least a second hollow profile section forming at least two profile chambers extending parallel to each other, a first profile chamber (9) being designed as a substantially circumferentially closed profile chamber and the second profile chamber (10) being designed as the compartment (11) for receiving the energy storage device, wherein at least the second profile chamber (10) has at least twopreferably comprising profile webs running within the profile cross-section, which extend at least over a partial length of the hollow profile section.

Description

[0001] The invention relates to a bicycle frame for an electrically powered bicycle, wherein the bicycle frame comprises frame parts selected from a group of frame parts comprising a top tube, a down tube, a seat tube, a head tube, chainstays and seat stays, and at least one motor bearing housing connecting the seat tube and the down tube, wherein at least the down tube is designed as a hollow profile with at least one compartment for receiving at least one electrical energy storage device.

[0002] A bicycle frame of the type mentioned above is known, for example, from WO 2018 / 042269 A1. The down tube of the bicycle frame known from WO 2018 / 042269 A1 comprises two receiving compartments arranged side by side in the direction of extension of the frame strut or the respective frame tube, each for accommodating a power supply unit. This measure serves to increase the range of the e-bike. The section of the frame containing the receiving compartments has a profile cross-section that is symmetrical with respect to the direction of extension of the receiving compartments and is preferably designed as an H-profile, I-profile, or T-profile cross-section. The receiving compartments are designed so that the batteries can be removed laterally.

[0003] A bicycle frame of the type described above, designed to accommodate multiple batteries, must possess a corresponding level of rigidity. Furthermore, the frame must be designed to withstand the high drive torques associated with the motor. This necessitates that the frame profiles exhibit a high degree of material stiffness.

[0004] Especially for e-bikes designed for sporty use, the system weight plays a significant role. In this context, the stiffness-to-weight ratio of the components used in frame construction is of particular importance.

[0005] The invention is based on the objective of providing a bicycle frame of the type mentioned above, which has a particularly good stiffness-to-weight ratio and is especially suitable for electric bicycles intended for sporting use. Furthermore, the bicycle frame according to the invention should be designed in such a way that its manufacture is relatively simple.

[0006] The problem underlying the invention is solved by providing a bicycle frame with the features of claim 1. Advantageous embodiments of the invention are set out in the dependent claims.

[0007] A first aspect of the present invention relates to a bicycle frame for an electrically powered bicycle, wherein the bicycle frame comprises frame parts or frame sections selected from a group of frame parts comprising a top tube, a down tube, a seat tube, chain stays and seat stays, and at least one motor mounting housing connecting the seat tube and the down tube, wherein at least the down tube is designed as a hollow profile with at least one compartment for receiving at least one electrical energy storage device. The bicycle frame according to the invention is characterized in particular by the fact that at least the down tube comprises a first and at least a second hollow profile section, which form at least two profile chambers extending parallel to each other, at least one first profile chamber being, substantially preferably, a fully enclosed profile chamber over its entire length.formed with a closed profile cross-section, and the second profile chamber is designed as the compartment for receiving the energy storage device, wherein at least the second profile chamber comprises at least two profile webs, preferably running within the profile cross-section, which extend at least over a partial length of the hollow profile section.

[0008] The cross-sectional profile of the down tube is preferably non-circular or angular. When the term "tube" is used below, it does not necessarily mean that the corresponding frame component has a round cross-section. The first profile chamber preferably has a smaller cross-section than the second profile chamber. The second profile chamber is preferably only formed with a fully closed cross-section over certain sections.

[0009] In particular, the geometric design of the profile chambers of the hollow profile section designed to accommodate the energy storage device is adapted according to the invention such that the hollow profile section in question can be manufactured relatively easily, for example by injection molding or extrusion from both plastic and aluminum. An increase in the bending stiffness of the profile or the area moment of inertia of the profile is achieved with relatively little material usage by the profile webs, which preferably run within a profile cross-section.

[0010] In a preferred embodiment of the bicycle frame according to the invention, the compartment for receiving the energy storage device may have an upper opening facing the user during normal use of the bicycle frame, for removing or inserting the energy storage device. This opening can be closed with at least one, preferably separate, cover or a housing for the energy storage device adapted to the contour of the compartment. Particularly in this embodiment of the bicycle frame, the closed profile chamber of the hollow profile section forming the down tube of the bicycle frame preferably extends below the compartment for the energy storage device, so that the energy storage device, in the form of a rechargeable battery or accumulator, is supported by the closed profile chamber in its installed position. In particular, a hollow profile designed with several profile chambers can achieve a relatively high bending stiffness with a relatively small amount of material.exhibit a relatively high area moment of inertia.

[0011] The bicycle frame according to the invention can be designed as a so-called step-through frame without a top tube. This is possible in particular because the down tube has a correspondingly high bending stiffness as well as torsional stiffness.

[0012] Preferably, the profile webs are designed as reinforcing ribs of the second profile chamber, each forming a longitudinally extending rim or lateral boundary of the opening for removing or inserting the energy storage device.

[0013] Preferably, the profile ribs extend outside the neutral fiber of the down tube, in particular outside the neutral fiber of the second profile chamber, and furthermore into the upper area of ​​the second profile chamber facing the user during the intended use of the bicycle frame by a user.

[0014] In a particularly preferred embodiment of the bicycle frame according to the invention, the profile webs may each have a contour that facilitates demolding from a tool, preferably at least one draft angle. This is particularly advantageous if the relevant hollow profile section of the bicycle frame is designed as a plastic hollow profile, for example, obtained by injection molding of thermoplastic material.

[0015] The bicycle frame according to the invention can be manufactured in one piece and from a single material. Alternatively, the bicycle frame can also be assembled from several hollow profile sections, which are joined, for example, at the frame's nodes, i.e., in the area of ​​the frame's stress points, using connectors or sleeves.

[0016] Particularly to achieve a favorable stiffness-to-weight ratio, it is advantageous if at least some frame components, preferably at least the seat tube and the down tube, are designed as hollow profile sections with a defined wall thickness and a defined, and preferably smooth, inner contour. This allows for a uniform and thin wall thickness along the length of the hollow profile sections, and thus a low weight. A defined wall thickness of the hollow profile sections can be achieved, for example, by extrusion, compression molding, or injection molding.

[0017] For the purposes of the invention, "smooth" or "smooth-walled" means in particular that the surface in question has a roughness Ra between 0.4 µm and 18 µm.

[0018] A preferred and advantageous variant of the bicycle frame according to the invention is characterized in that at least some of the frame parts are made of a fiber-reinforced thermoplastic material.

[0019] Advantageously, at least one main frame of the bicycle frame, comprising at least the seat tube, the down tube, and a head tube, is injection-molded in one piece from a thermoplastic material preferably reinforced with tensile fibers. The thermoplastic material may be a thermoplastic material filled with short fibers. For the purposes of this application, short fibers are understood to be fibers with a length greater than 0 mm and less than 50 mm, whereas long fibers are tensile fibers that may have a length greater than 50 mm up to an infinite length. The tensile fibers may comprise carbon fibers, aramid fibers, glass fibers, or basalt fibers.

[0020] A main frame of a bicycle according to the present invention is that part of the bicycle frame which comprises at least a seat tube, a motor mount housing, a down tube, and a head tube. The main frame may further comprise a top tube which is connected to the head tube and the seat tube. According to one embodiment of the invention, the main frame of the bicycle frame may include a top tube, whereas in another embodiment, the main frame may be designed without a top tube.

[0021] A further component of the bicycle frame according to the invention is a rear triangle. For the purposes of this invention, a rear triangle is understood to mean the seat stays and chain stays of the bicycle frame, including the dropouts. The term "chain stays" encompasses the corresponding structurally load-bearing elements of the bicycle frame, even in the case of a bicycle that, for example, incorporates a belt drive. Generally, a fork is also considered a component of a bicycle frame; however, it is not the subject of this application.

[0022] In one variant of the bicycle frame according to the invention, at least some of the frame tubes may be reinforced, at least in certain areas, with laid and / or woven tensile-strength long fibers or continuous fibers. The long fibers, as well as the short fibers mentioned above, may be selected from a group of fibers including carbon fibers, glass fibers, aramid fibers, Kevlar fibers, and basalt fibers.

[0023] Preferably, at least all frame tubes of the main frame are manufactured by injection molding of thermoplastic material using a plurality of movable molded parts. The thermoplastic material can be selected from a group of plastics including PA (polyamide), PP (polypropylene), PPA (polyphthalamide), PS (polystyrene), PE (polyethylene), ABS (acrylonitrile butadiene styrene), PC (polycarbonate), POM (polyoxymethylene), PEK (polyetherketone ketone), PEEK (polyetheretherketone), PA6 (polyamide 6), PA6.1 (polyamide 6.1), PA 12 (polyamide 12), HPPA (high-performance recycled polyamide), PARA (polyarylamide), PBT (polybutylene terephthalate), and PK (polyketones).

[0024] The bicycle frame according to the invention can also include extruded aluminum profiles. In principle, the bicycle frame according to the invention can be constructed from either hollow plastic profile sections or extruded aluminum profile sections.

[0025] One variant of the bicycle frame according to the invention is characterized by a modular design, wherein the down tube is designed as an aluminum extrusion profile.

[0026] The invention is explained below with reference to and based on an embodiment illustrated in the accompanying drawings.

[0027] They show: Fig. 1 a perspective view of the bicycle frame according to the invention, Fig. 2 a perspective view of the down tube of the bicycle frame according to the invention, Fig. 3 a longitudinal section through the main frame and Fig. 4 a cross-section through the down tube.

[0028] The in Fig. The bicycle frame 1 shown in Figure 1 is designed as the frame of an electric bicycle. The bicycle frame 1 comprises a rear triangle 2 with chainstays 3 and seat stays 4. The main frame includes a seat tube 5, to which the seat stays 4 and the chainstays 3 of the rear triangle 2 are connected, as well as a down tube 6 and a head tube 7 which is designed in a known manner to accommodate a headset and a steerer tube of a front fork.

[0029] The seat tube 5 is designed in a known manner to accommodate a seat post. The rear triangle 2, for example, is designed to accommodate a thru-axle for a rear wheel.

[0030] The seat tube 5 and the down tube 6 are integrally connected to a motor mount housing 8 for accommodating an electric motor (not shown). At least the seat tube 5 and the down tube 6 are designed as hollow profiles, with the down tube 6 comprising a first and at least a second hollow profile section, forming at least two profile chambers 9, 10 extending parallel to each other. The first profile chamber 9 is designed as a substantially fully enclosed profile chamber, and the second profile chamber 10 is designed as the compartment 11 for accommodating the energy storage device. The second profile chamber 10 has an upper opening 12 for accommodating the energy storage device, which is in the form of a battery. The energy storage device can be inserted from above into this opening. The opening 12 can be closed either with a separate cover or with a part of the energy storage device housing. The energy storage device can be locked into the compartment 11 of the down tube 6.

[0031] As this is particularly evident from the depictions in the Fig. 3 and Fig. The second profile chamber 11, which is removable from the lower tube 6, comprises two opposing profile ribs 13 projecting into the interior. These ribs extend above the neutral axis of the profile cross-section when the bicycle frame 1 is in its intended position and each forms a rim around the opening 12 of the compartment 11. The ribs 13 do not extend over the entire length of the lower tube 6, a consequence of the bicycle frame being manufactured as a single-piece injection-molded component from thermoplastic. For this reason, the ribs 13 each have draft angles 14 on their upper and lower surfaces to facilitate demolding from an injection mold.

[0032] The first profile chamber 9 is designed as a fully enclosed profile chamber and extends continuously from the motor bearing housing 8, which is open at the bottom on the bearing side, to the steering tube 7. Reference symbol list 1 bicycle frame 2 Rear triangle 3 chainstays 4 seat stays 5 seat tube 6 down tube 7 Head tube 8 engine mount housings 9 first profile chamber 10 second profile chamber 11 subjects 12 Opening 13 ribs 14 draft angles QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] WO 2018 / 042269 A1

[0002]

Claims

[1] Bicycle frame (1) for an electrically powered bicycle, wherein the bicycle frame (1) comprises frame parts selected from a group of frame parts comprising a top tube, a down tube (6), a seat tube (5), a head tube (7), chainstays (3) and seat stays (4), and at least one motor bearing housing (8) connecting the seat tube (5) and the down tube (6), wherein at least the down tube (6) is designed as a hollow profile with at least one compartment (11) for receiving at least one electrical energy storage device, at least the down tube (8) comprises a first and at least a second hollow profile section forming at least two profile chambers extending parallel to each other, a first profile chamber (9) being designed as a substantially circumferentially closed profile chamber and the second profile chamber (10) being designed as the compartment (11) for receiving the energy storage device, wherein at least the second profile chamber (10) has at least twopreferably comprising profile webs running within the profile cross-section, which extend at least over a partial length of the hollow profile section. [2] Bicycle frame (1) according to claim 1, characterized by , that the compartment (11) for receiving the energy storage device has an upper opening (12) facing the user during normal use of the bicycle frame for removing or inserting the energy storage device, which can be closed with at least one, preferably separate, cover or housing of the energy storage device. [3] Bicycle frame (1) according to one of claims 1 or 2, characterized by , that the profile webs are designed as reinforcing ribs of the second profile chamber (10), each forming a longitudinally extending rim of the opening (12) for removing or inserting the battery storage. [4] Bicycle frame (1) according to any one of claims 1 to 3, characterized by, that the profile ribs extend outside the neutral fiber of the down tube (6), in particular outside the neutral fiber of the second profile chamber (10) and furthermore into the upper area of ​​the second profile chamber (10) facing the user when the bicycle frame (1) is used as intended by a user. [5] Bicycle frame (1) according to any one of claims 1 to 4, characterized by that the profile webs each have a contour that facilitates demolding from a tool, preferably at least one demolding slope (14). [6] Bicycle frame (1) according to any one of claims 1 to 5, characterized by , that at least some frame parts, preferably at least the seat tube (5) and the down tube (6), are designed as hollow profile sections with a defined wall thickness and a defined and preferably smooth-walled inner contour. [7] Bicycle frame (1) according to any one of claims 1 to 6, characterized bythat at least some of the frame parts are made of a fiber-reinforced thermoplastic material. [8] Bicycle frame (1) according to any one of claims 1 to 7, characterized by , that at least one main frame comprising at least the seat tube (5), the down tube (6) and a head tube (7) is injection molded in one piece from a thermoplastic material preferably reinforced with tensile fibers. [9] Bicycle frame (1) according to any one of claims 6 to 8, characterized by , that at least some of the frame parts are reinforced, at least in certain areas, with laid and / or woven tensile long fibers. [10] Bicycle frame (1) according to any one of claims 1 to 9, characterized by , that at least all frame parts of the main frame were obtained by injection molding of thermoplastic material using a large number of movable molded parts. [11] Bicycle frame (1) according to any one of claims 1 to 10, characterized bythat at least the down tube is designed as an aluminum extrusion profile.

Images